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The Faraday effect in trans-decahydronaphthalene, normal octadecane and normal docosane Forster, John H. 1946

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THE. FARADAY EFFECT IN TRANS-DECAHYDRONAPTHALENE. NORMAL OCTADECANE AND NORMAL DOGOSANE by John H. Forster A Thesis submitted i n p a r t i a l f u l f i l m e n t of the requirements for the degree of MASTER OF ARTS i n the DEPARTMENT OF PHYSICS at the UNIVERSITY OF BRITISH COLUMBIA A p r i l 1946. A C K N O W L E D G M E N T The author wishes to express his appreciation of the generous assistance and encouragement given by Dr. H. D. Smith under whose guidance t h i s work was performed. In addition, gratitude should be expressed f o r the advice and help of Dr. W. E. Seyer of the Chemistry Department. CONTENTS I. Discussion of the Faraday E f f e c t (a) General (b) Dispersion (c) Temperature E f f e c t s (d) Molecular Rotation I I . The Present Investigation (a) Isomers of Decahydronapthalene (b) Normal Pa r a f f i n s III.. Experimental (a) Apparatus and Materials 1. Samples 2. Magnet and Polarimeter 2. Light Sources 4 . Heating System and Tubes (b) General Methods 1. Procedure 2. C a l i b r a t i o n IV. Results (a) Trans-Decahydronapthaiene 1. Verdet Constant 2. Dispersion Constants 3. Temperature Rotation E f f e c t (b) n-Octadecahe and n-Docosane 1. Verdet Constants 2. Dispersion Constants 2. Temperature Rotation E f f e c t V. Summary and Conclusions (a) Summary (b) Conclusions VI. Bibliography THE FARADAY EFFECT IN TRANS-DECAHYDRONAPTHALENE. NORMAL QCTADSCANE AND NORMAL DOCOSANl GENERAL DISCUSSION OF THE FARADAY EFFECT (a) General I f an incident beam of plane polarized l i g h t be passed through a transparent i s o t r o p i c medium and a strong magnetic f i e l d be impressed upon the material so that Inhere i s a component of f i e l d strength along the axis of the l i g h t path, then a ro t a t i o n of the plane of p o l a r i s a t i o n of the emerging beam w i l l be detected. This phenomenon was f i r s t observed by-Faraday i n 1845, and i s referred to as the Faraday e f f e c t or as magneto-optic r o t a t i o n . The degree of o p t i c a l r o t a t i o n may be determined by use of the same p o l a r i z i n g equipment as i s used i n the detection of natural o p t i c a l a c t i v i t y . However, the phenomenon of magnetic o p t i c a l r o t a t i o n i s more cl o s e l y r e l a t e d t h e o r e t i c a l l y to the Zeeman e f f e c t than i t i s to natural o p t i c a l a c t i v i t y . This becomes more obvious when the following c h a r a c t e r i s t i c s of the Faraday e f f e c t are noted. ( i ) The d i r e c t i o n of ro t a t i o n may be reversed by reversing the d i r e c t i o n of the magnetic f i e l d . ( i i ) The Faraday e f f e c t i n solutions i s not proportional to concentration. ( i i i ) When the l i g h t beam i s r e f l e c t e d back through the medium, the amount of ro t a t i o n i s doubled. Investigations by Verdet about 1856 demonstrated that f o r a given substance the angle of ro t a t i o n i s proportional to the f i e l d strength applied and to the length of the column of material plaeed i n the f i e l d . The constant of pro p o r t i o n a l i t y has been c a l l e d the Verdet constant, and i s a c h a r a c t e r i s t i c of the substance involved. I t depends very l a r g e l y on density or state of the medium. Then i f 5 i s the Verdet constant i n minutes per gauss-cm. and H = f i e l d strength i n Gauss I f the f i e l d strength i s not uniform over the length of the tube, then where Hj_ i s the magnetic p o t e n t i a l at any point i n the tube. (b) Dispersion H. A. Lorentz (1) pointed out the intimate r e-(1) H. A. Lorentz, "Theory of Electrons", B. G. Teubner, and 1 - length of column of substance to be examined and 0 = angle of r o t a t i o n i n degrees L e i p z i g . 3. l a t i o n between the Zeeman E f f e c t and the Earaday Ef-f e c t . Elementary theory of the Zeeman ef f e c t predicts that f o r a propagation along the l i n e s of force two oppositely c i r c u l a r l y polarized l i g h t rays w i l l t r a v e l with d i f f e r e n t v e l o c i t i e s . Then a beam of l i g h t should have i t s plane of p o l a r i z a t i o n turned as i t trave l s onward. I t may be considered that the existence of two . indices of r e f r a c t i o n and, therefore, a difference i n v e l o c i t y of the two rays may be ascribed to the ad-d i t i o n of the Larmor processional v e l o c i t y of the electrons i n the molecule about the f i e l d axis to t h e i r large angular v e l o c i t y i n other d i r e c t i o n s . M i l l s (2) measured the v e l o c i t i e s of the two c i r -c u l a r l y polarized components and found that the ray which t r a v e l l e d with the greatest v e l o c i t y was the one whose d i r e c t i o n of c i r c u l a r v i b r a t i o n was the same as that of the current producing the f i e l d . Larmor (3) has shown that the amount of p o l a r i -zation per unit length of the medium obtained i n the above manner i s given by where vj. .= the v e l o c i t y of right-handed component of (2) M i l l s , Phys. Rev., 18, 65, (1904) (3) Larmor, "Aether and Matter", Cambridge University (b) the incident wave t r a i n . Press, p. 352 V £ 1 3 the velocity of the left-handed component of the incident wave train. The faotor - -Jr) is the difference in time transit which is also given by c (c) where Wp is the precessional effect and v is velocity in absence of field and JL ojp « \A radians per sec (d) C e = charge of electron in e.s.u. m = mass of electron in gm. Also w = ^ (e) A where wavelength of the incident light beam and c = velocity of light If the index of refraction of the medium is n, then using (e) and (d) it can be shown that We see that from equation (f) a definite variation can be expected in the Verdet constant as the wavelength increases. If i t is supposed that the ordinary dis-persion of the medium can be represented by an equation of the type: • f ^ - l * h 4 -=^- + (g) Where ^„ ^ are wavelengths corresponding to the "free periods" of the molecules, and bQ, b 1 ? and bg are con-stants. I f the wavelength of incident r a d i a t i o n A i s very close to that of the free period, or absorption frequency , , then the secondary terms have l i t t l e e f f e c t and the natural dispersion of the medium may be written as I t may also be shown i n consideration of equa-tions (h) and ( f ) , that the magneto-optical dispersion may be given by the equation m % = k"(s8rr ( i ) where K 1'is a constant, and ^, i s the wavelength cor-responding to the natural dispersion frequency of the eleotrons i n the molecule of the medium i n question. Walters and Evans (4) have investigated the magneto-optical dispersion of a large number of or-ganic l i q u i d s , and have found that p r a c t i c a l l y a l l of the magneto-optioal dispersions of the molecules can be represented by the above type of equation. The absorption frequencies or so-called free periods of the molecules are usually found i n the u l t r a - v i o l e t region of the spectrum, and the wavelength corres-ponding to t h i s frequency j \ , was found to increase with the molecular weight of the organic substance used. There i s also an inerease i n K-^ with molecular (4) Walters and Evans, Phil. Mag. 22, 8l6, (1936), and series of following papers in the same Journal. weight. This would s i g n i f y that f o r the compounds mea-sured, there i s only one natural frequency of the dispersion electrons f o r a wavelength near the v i s i b l e spectrum. Therefore, a measurement of the v a r i a t i o n of the Verdet constant with wavelength f o r any substance should y i e l d i n t e r e s t i n g information regarding the absorption regions i n the u l t r a - v i o l e t , as well as providing a means of c a l c u l a t i n g the Verdet constant of the substance f o r any wavelength of l i g h t , (c) Temperature Rotational E f f e c t s The v a r i a t i o n of the Verdet constant with tem-perature i s an extremely small one, and 5 i s not by any means a predictable function of temperature. However, i f temperature i s plotted against r o t a t i o n f o r a given substance a smooth curve i s usually ob-tained, since the Verdet constant i s re l a t e d con-tinuously to the density at any temperature, or to the r e f r a c t i v e index at any temperature. An example of the v a r i a t i o n of the Verdet constant with tempera-ture i s given by the r e l a t i o n f o r water (5)> which i s a* = % x o { i - i53(±-ao)io4-3.ofc(i-ao)icrf(*) i n the temperature range 5° to 100°C. X where » Verdet constant at i °C and wavelength * {5) Int. C r i t . Tables, Vol . 6 , p. 425 5ao« Verdet constant at 20°C and wavelength A t = temperature of water in °C However, some substances may have a linear re-lationship existing between the two quantities. In general then = 5 a o t l < - A(±-20) - B(±-20 )* j where A or B may be zero or negative, but where both A and B cannot be zero, (d) Molecular Rotation In obtaining a measure of comparative magnetic rotatory power, the earlier investigators very often compared the rotation of a length of fluid substance to that of an equivalent length of water under the same conditions. In opposition to this, Perkin (6) advanced a standard of molecular rotation by referring the results of observations of unit lengths of fluids to the lengths of columns of liquid which would be formed by the condensations of unit lengths of their vapors; in other words, to lengths related to each other in proportion to their molecular weight, making the necessary connection for difference of densities. On the basis of such a definition (M), the molecular rotatory power is given by: (6) Perkin, Trans. Chem. Soc. XLV p..421 (1884); IXLX p.1060,(1896); LI p.562-808 (1887); XOI p.806 (1907); and others in the same Journal. where m = molecular weight of l i q u i d investigated mA = molecular weight of water d » density of l i q u i d investigated d^ « density of water and S and 3 ' are the Verdet constants of the l i q u i d and of water respectively. In a further series of investigations on organic l i q u i d s , Perkin examined the rotations of many members of various homologous series of hydrocarbons. He was able to deduce a rule empirically which predicted f a i r l y w e ll the molecular rotations of some se r i e s , but which showed poor agreement i n a great many other cases. Since then other investigators have t r i e d with only moderate success to devise an expression which would give molecular rotatory power as a sum of contributions of the various atomic values i n the or-ganic molecule. Rosenfeld (7) has attempted a quantum mechanical treatment of magneto-optical r o t a t i o n . Re-s u l t s of t h i s theory give an additive formula f o r the Verdet constant, but the presence of so many unknown constants makes c a l c u l a t i o n impractical. In general, the magnetic r o t a t i o n of hydrocarbons i s rather independent of configuration of atoms. How-ever, small changes can be detected. Perkins formula gives a f a i r l y close approximation f o r some hydro-(7) Rosenfeld, Z. Physik, 57, 855-54 (1929). carbons, but i t i s usually i n error i n the t h i r d s i g n i f i g a n t f i g u r e . I I . NATURE OF THE INVESTIGATION (a) The Isomers of Decahydronapthalene With the improvement of f r a c t i o n a t i o n methods, the separation of petroleum into i t s components has led to a wide i n t e r e s t i n the Chemical compositions and physio-chemical properties of the compounds to be found i n these petroleum f r a c t i o n s . Many fam i l i e s of hydrocarbons and derivatives have been i s o l a t e d f o r study by f r a c t i o n a l methods. Among the d i f f e r e n t hydrocarbons to be found i n o i l s are those belonging to the hydrogenated c y c l i c hydro-carbons, the napthenes. A basic compound among the dihapthenes i s decahydronapthalene (C^H^g) (Mol.W = 138.246). The commercial product i s referred to as decalin. A f t e r the discovery of a,,practical method of fr a c t i o n a t i n g commercial decalin to obtain two isomers of the product by Seyer and Walker (8) a considerable amount of investigation of the decahydronapthalene molecules has been accomplished. As a r e s u l t of the work done on the subject, i t i s now believed that t h i s naphthene exists i n f i v e stereo-isomeric forms. (8) Seyer and Walker, J. Amer. Chem. S o c , 60, 2125 (1938). Apparently the most stable of these isomers are the ois and trans forms. The physical properties of the two isomers are very i n t e r e s t i n g . Each isomer exhibits p e c u l i a r i t i e s by which have as yet not been s a t i s f a c t o r i l y explained. In investigations of the temperature e f f e c t on physical properties, i n p a r t i c u l a r s p e c i f i c heat (9), and sur-face tension (10), the both forms have shown abnor-m a l i t i e s . Mizuhara (11) investigated the v a r i a t i o n of r e -f r a c t i v e index with temperature f o r both the e i s and trans forms, and found the r e f r a c t i v e index of c i s . decalin to vary l i n e a r l y with temperature i f discon-t i n u i t i e s i n the v a r i a t i o n were assumed at about 28°C and j>l°C. He interpreted these as being t r a n s i t i o n temperatures f o r three isomers of the c i s decalin. The study of the Raman ef f e c t by Zotov (12) seemed to indicate further a t r a n s i t i o n point i n t h i s tempera-ture region. I t i s important to note that i n the re-gion observed (20° to 80°), no di s c o n t i n u i t y i n the l i n e a r temperature-refractive index function was i n -dicated by Mizuharats r e s u l t s f o r trans decalin. (9) Davies, G. F., M.A.Sc. Thesis, 1939. (10) Davenport, C. H., B.A.Sc. Thesis, 1939. (11) S. J . Mizuhara, M.A. Thesis, 1941. (12) Zotov, G., M.A. Thesis, 1941. n MeLeod (15) investigated the l i n e a r v a r i a t i o n of the Verdet constant with temperature of c i s de c a l i n . Since the v a r i a t i o n i s an extremely small one, i t i s d i f f i c u l t to measure. However, McLeod's r e s u l t s f u r -ther indicated that some change took place i n the Verdet constant of c i s decalin i n the temperature r e -gion near 51°C. A l l t h i s work seemed to indicate that of the two isomers, c i s was the most unstable. Among the hypo-t theses advanced to account f o r the discontinuity was that the"sample of c i s undergoes a t r a n s i t i o n to a second isomeric form at 51°C. Up to t h i s time, no abnormalities had been en-countered i n the physical properties of trans decalin. When the present research was undertaken, i t was pro-posed to investigate the temperature r o t a t i o n e f f e c t of trans-decalin, i n order to v e r i f y the abnormality behavior of the c i s isomer. I t was assumed that the va r i a t i o n with temperature would be a l i n e a r one; as has been indicated by other measurements on t h i s type of compound. Work was commenced on t h i s problem, and during the course of research, i t was indicated that the r e s u l t s were -not going to be as expected. However, new information was indicated by the investigation by Seyer and Mann (14) of the tempera-(13) H.D.Smith and R.R.McLeod, J.Amer.Chem.Soc. (In Press) (14) W.F.Seyer and C.W.Mann, J.Amer.Chem.Soc., 67, 528, (1945). 12. t u re v a r i a t i o n o f the vapor pressure o f t r ans d e c a l i n . I f the l o g o f the vapor pressure P i s p l o t t e d aga ins t the i nve r se o f the temperature the graph shows a s t r a i g h t l i n e r e l a t i o n s h i p w i t h an abrupt change o f s lope i n the temperature r e g i o n o f 8 0 ° . S ince the o ther p h y s i c a l p r o p e r t i e s ( i . e . r e f r a c t i v e index) o f the t r ans isomer had not been i n v e s t i g a t e d to su f -f i c i e n t l y h i g h temperatures to i n d i c a t e any such changes i f they d i d e x i s t , then the doubt was s t i l l l e f t open as to-whether the t r ans form was as r e g u l a r as supposed. In f u r t h e r experiments on s p e c i f i c heat by Seyer fno t as y e t r c o m p l e t e ) , there are i n d i c a t i o n s o f such ah abnormal i ty o c c u r i n g . Therefore , the pr imary purpose o f the r e sea rch undertaken on t r ans d e c a l i n was to d e t e c t , i f pos-s i b l e , any abnormal i ty i n the Verdet constant tempera-tu re curve o f t r ans d e c a l i n . Th i s meant t ha t the tem-pera ture range had to be g r e a t l y extended. Of f u r t h e r i n t e r e s t i n connec t ion w i t h the isomers o f d e c a l i n , are the c h a r a c t e r i s t i c a b s o r p t i o n f r e -quencies o f the d i s p e r s i o n e l e c t r o n s . E q u a t i o n ( i ) may be r e w r i t t e n i n the form where V and V G are the f requenc ies cor responding to the wavelengths ^ and \ o f formula ( i ) . Thus t h i s equat ion p rov ides an accura te means o f e v a l u a t i n g the frequency V0>, which should he a c h a r a c t e r i s t i c ab-sorption frequency of the compound. Since t h i s frequency f o r compounds such as de c a l i n i s usually i n the u l t r a - v i o l e t region of the spectrum, beyond the absorption l i m i t of a i r , i t i s d i f f i c u l t to mea-sure by ordinary methods. McLeod has obtained the value of t h i s frequency f o r c i s decalin, and i t was hoped that i t s c a l c u l a t i o n f o r trans decalin would throw some, l i g h t on the s t r u c t u r a l r e l a t i o n s h i p be-tween the two isomers. Thus the purpose of t h i s i n v e s t i g a t i o n of the magneto-optical properties of trans decalin was to accomplish also the following: (1) To obtain an accurate value of the Verdet constant of trans decahydronapthalene, and to c a l -culate from t h i s a value of the molecular rotary power of the isomer. (2) To calculate the natural absorption f r e -quency of the isomer by the method of magneto-optical dispersion, or at l e a s t to v e r i f y whether or not an equation of the type (1) w i l l apply f o r measurements i n the v i s i b l e region of the spectrum. (3) To measure the temperature r o t a t i o n e f f e c t of trans decahydronapthalene i n the range 20° to 110°C. (4) To in t e r p r e t the signifigance of these r e s u l t s i n the l i g h t of possible s t r u c t u r a l changes. (b) The P a r a f f i n S e r i e s o f Hydrocarbons A great amount o f recen t work has a l s o been done on the p h y s i c a l p r o p e r t i e s o f the normal p a r a f f i n s e r i e s o f s a tu ra t ed hydrocarbons . These be long to a homologous s e r i e s , the gene ra l chemica l formula be ing C n H(2n + 2 ) . The molecule i s o f the l o n g c h a i n t y p e : ? ? H-C—C C-H i i I H H H the l e n g t h of the c h a i n depending on the number o f groups i n the mo lecu le . Seyer (15) has i n v e s t i g a t e d the d e n s i t y and. t r a n s i t i o n p o i n t s o f a l l the even numbered hydrocarbons o f t h i s s e r i e s , beg inn ing w i t h and ending w i t h Gj^Hqo* A l l the lower even numbered hydrocarbons o f the . s e r i e s are f a i r l y r e g u l a r i n t h e i r d e n s i t i e s and t r a n s i -t i o n u n i t s , and i n o ther c h a r a c t e r i s t i c p h y s i o a l p r o -p e r t i e s . However, Seyer d i d f i n d t h a t f o r members o f the group compr i s ing G26, C28» C^ o» G'32 and 0^4, t h a t p o i n t s on t h e i r temperature curves cou ld be r e t r a c e d upon h e a t i n g or c o o l i n g , whereas f o r those numbered below C24 i n the s e r i e s , the d e n s i t y curve depended on whether o r not the temperature was i n c r e a s i n g o r d e c r e a s i n g . However, lower i n the s e r i e s , below G±Q, the d e n s i t y curve r e tu rned to the same form as f o r those above C24. I t thus appears tha t there i s some i r r e g u l a r i t y i n the t empera ture -dens i ty r e l a t i o n f o r (15) W.F .Seyer , R . F . P a t t e r s o n , J . K . K e a y s , J.Amer.Chem. S o c , 66, 179, (1944). 1 5 . the members of the series Gi8> c20» a n d c 2 2 # The Verdet constants of pentane (G-5 Hx2)> i s o -pentane, henane ( C D H14), isohexane, and heptane (Gq % D ) were measured by Perkin (16). Since then other members of the series have been investigated magneto-optically by others t i l l accurate data on the Verdet constants of the whole series as f a r as C12 I s known. However, since the heavier normal paraff i n s are s o l i d s at normal temperatures, l i t t l e or no work has been done on the magneto-optical pro-perties of these materials at temperatures above t h e i r melting points. However, some i n t e r e s t i n g information concerning the v a r i a t i o n of r e f r a c t i v e index with density f o r the normal paraffins has been obtained by Kurtz, (17). From the work of Kurtz and other investigators, i t may be shown that there i s a d i r e c t r e l a t i o n s h i p be-tween the number of dispersion electrons, and the number of formula bonds i n most hydrocarbons. He shows that t h i s number k may be calculated from theo-r e t i c a l considerations, (k = the number of dispersion electrons per formula bond, either C-C, or C-H.) He further shows that the Sellemeir-Drude equation, of the following type, holds f o r the normal p a r a f f i n (16) Perkin, Trans. Chem. Soc. XLV, 421, (1884). (17) S.S.Kurtz and M.R. L i p k i n , J.Amer.Chem.Soc., 63, 2158, (1941). series of hydrocarbons, as well as other s e r i e s . where B i s a constant. This equation i s analogous to the equation (h) given i n the theory when the constant b Q i s zero. When the temperature d i f f e r s from 20°, or the pres-sure d i f f e r s from one atmosphere, equation (m) becomes: ^ 1 B {OJ„*c*)*__Vx3* (n) where 0 i s k c o e f f i c i e n t , shown by Kurtz and Ward to be p *. O . / f l x i O ( o L ^ - o L p ) ot"*= density at temperature t, and pressure p and <L^= hypothetical density at 20°C and atomospheri© pressure. This «may be calculated from the molecular weight of the substance (18). I f an equation of t h i s type ensures the predic-t i o n of the r e f r a c t i v e index at any temperature and pressure f o r any member of the p a r a f f i n series then i t should be possible to write a s i m i l a r one, analogous to equation ( i ) , using the same c o e f f i c i e n t and the same c h a r a c t e r i s t i c frequency, \70 . This would take the form /to.* = K ( 0) {U7.H-0)*-Vvr (18) M.R.Lipkin and S.S.Kurtz, Ind.Eng. Ohem., Amal.Ed 13, 291, (1941). Thus, f o r a given temperature, i t should be pos-s i b l e to predict the Verdet constant at any wavelength for a temperature i n the range f o r which the $ co-e f f i c i e n t may be calculated. Since Ward and Kurtz did not investigate the Verdet constant of the para f f i n s , and such data was not available, i t was not known whether experimental measurement would lead to the same type of r e l a t i o n -ship as (o). Thus, vthe purpose of the in v e s t i g a t i o n of the Verdet constant of the two members of the p a r a f f i n series undertaken, (Octadecane (CloHjg) Docosane (°22^46^» c a n b e summarized as follows: (a) To obtain accurate values of the Verdet con-stants of Octadecane and Docosane above t h e i r melting points, and to obtain the molecular rotatory power for comparison with other more normal members of the par a f f i n s . (b) To investigate the temperature-rotation ef-f e c t i n Octadecane,"with a possible detection of any abnormality immediately above the melting point. (c) To investigate whether or not the temperature c o e f f i c i e n t may be used to predict a change i n d i s -persion frequency f o r these members of the se r i e s , to f i n d the actual frequency ( V o+0 ), (which w i l l be an absorption l i n e of the substance), and to check the accuracy of the equation (n) f o r the two members of 18. the series considered. IH. EXPERIMENTAL (a) Apparatus and Materials 1. Samples The sample of trans decalin used i n t h i s experiment was obtained by Dr. Seyer of the Chemistry Department, from commercial decalin by the r e c t i -f i c a t i o n process mentioned before. The sample had a fre e z i n g point of -30.84°C. This value i s s l i g h t l y lower than the values given by the International C r i t i c a l Tables f o r t h i s substance* The Octadecane and Docosane were the same samples as those used by Seyer and Walker i n deter-mining the density and t r a n s i t i o n points. The melting points were 28.1°C and 44.1°C respectively. 2. Magnet and Polarimeter The magnet and polarimeter used i n making the measurements are the same as those used by McLeod i n his investigations. The electromagnet i s of the type used i n work on the Zeeman e f f e c t . The f i e l d i s produced by two large c o i l s wound with wire of large current carrying capacity. The c o l l s are provided with three cooling jackets which are fed with a steady flow of tap water. In spi t e of t h i s , i t was found that the maximum amount A general View of the Apparatus of current that can be c a r r i e d without overheating the c o i l s i s about 30 amps. The magnet was f i t t e d with three standard sets of soft i r o n pole pieces, two of which were d r i l l e d . The two pairs suitable f o r the purposes of the experiment were a p a i r of f l a t c y l i n -d r i c a l ones, and a set of moderately tapered conical poles. I t was found, strangely enough* that the f l a t c y l i n d r i c a l pole pieces produced a stronger f i e l d component along the c e n t r a l axis, than did the tapered conical ones. These then were used f o r a l l further measurements. Many of the experimenters i n t h i s f i e l d have used long solenoids rather than electromagnets f o r production of the f i e l d . v However, the samples of l i q u i d obtainable were extremely small, so that a solenoid of appro-priate length would have been useless since i t would not produce nearly the f i e l d strength required f o r an observable r o t a t i o n . In the case of the electromagnet, the strength of the f i e l d increased with shorter length of the tube, thereby compensating somewhat f o r the shorter column of l i q u i d . The e l e c t r i c a l c i r c u i t f o r the e l e c t r o -magnet may be seen on Plate II (Fig. 1). A and B; are the two - f i e l d c o i l s i n p a r a l l e l . C i s a reversing switch, so that d i r e c t i o n of current through both c o i l s may be reversed. D i s a variable carbon reostat PLATE I I f o r f i n e adjustment of currents, and F i s a large cur-rent carrying step reostat. When high currents were desired, i t was necessary to throw the large resistance F out of the c i r c u i t . This was done by means of the switch E. G i s a Weston mirror scale millivoltmeter c a l i b r a t e d to read currents from 0 to 50 amperes when i n p a r a l l e l with the standard shunt. The ammeter had previously been checked, and found to read to within .5 percent. The pot e n t i a l source H i s a 110 v o l t motor generator, which provided f a i r l y steady current. The P o l a r i s e r and Analyzer used were manu-factured by Adam Hilger. This was a Half-Lippich system. Three prisms of the Lippich type were mounted on the p o l a r i z s r . The action of the system has been well described by MeLeod i n his t h e s i s , and need not be mentioned'here. I t was found that the accuracy of the readings was greatly influenced by the p o s i t i o n of the hal f shadow angle, and that f o r decreasing wavelengths, i t was necessary to increase the angle i n order to obtain consistant readings. The s l i t ar-rangement was also adapted to the nature of the l i g h t source used. The verniers enabled one to read the r o t a t i o n of the analyzer accurately to within 0 .01°. I t was necessary to b u i l d stands to accomodate the p o l a r i z e r and analyzer so that they could be properly l i n e d up with the d r i l l e d holes i n the magnet cores. Adjusting screws on the stands permitted adjustments of the p o l a r i z e r and analyzer to be made a f t e r these parts were fi r m l y mounted i n approximate alignment. 3. Light Sources A suitably intense source of sodium D l i n e s was provided by a General E l e c t r i c A u x i l l i a r y Resis-tance Sodium Lab-Arc operating on 110 v o l t s A.C. During the e a r l i e r research, the mercury radiations *6234, >5779, >546l, and ?v5893 were separated by means of a Hilger Monochromatic illuminator. The source used i n conjunction with the monochromator was a 100 watt General E l e c t r i c Mercury Arc, which operated i n conjunction with a transformer on a 110 v o l t A.C. c i r c u i t . Laiter, when temperature r o t a t i o n readings were rechecked, the Mercury l i n e s were i s o l a t e d by a set of Corning Heat Resisting glass f i l t e r s of stan-dard thickness. These provided an extremely s a t i s -factory source when placed d i r e c t l y between the po l a r i z i n g prism and the source. The p o s i t i o n of the source was an extremely c r i t i c a l one, p a r t i c u l a r l y i n the case of the p a r a f f i n hydrocarbons, where the combination of a high index of re f r a c t i o n of the l i q u i d and a small tube contributed to many extremely troublesome r e f l e c t i o n s , which made accurate readings d i f f i c u l t to obtain. However, af t e r a considerable period of time was spent i n a l i g n i n g the l i g h t source, the monochromator and the tube i n the f i e l d , most o f the r e f l e c t i o n s were e l i m i n a t e d . 4. Hea t ing System and Tubes Heat c o n t r o l presented a f a i r l y d i f f i c u l t problem. The a c t u a l v a r i a t i o n o f the Verdet cons tant w i t h temperature i s ve ry s l i g h t . I t was found by a se -r i e s o f p r e l i m i n a r y experiments w i t h a hea t ing system s i m i l a r t o the one used by MeLeod tha t a v a r i a t i o n o f temperature o f ±1° o r even more d i d not change the observable r o t a t i o n by more than . 0 1 ° f o r the f i e l d s t r e n g t h a v a i l a b l e . T h i s meant tha t the a c t u a l p r o -blem o f temperature measurement was r e l a t i v e l y s i m p l e . However, a ,g rea t source o f e r r o r was i n t roduced by changing temperature w h i l e readings were be ing t a k e n . A s l i g h t temperature g rad ien t a long the tube se t s up connec t ion cu r r en t s w i t h i n the l i q u i d . T h i s g ive s r i s e to " o p t i c a l inhomogenei t ies" i n the l i q u i d making accura te e s t i m a t i o n o f the e x t i n c t i o n p o i n t almost i m p o s s i b l e . Other i n v e s t i g a t o r s have encountered t h i s i n work ing on the Faraday e f f e c t i n c e r t a i n t e c h -n i c a l mix tu res o f hydrocarbons . U s u a l l y the d i f -f i c u l t y i s overcome by u s i n g a temperature c o n t r o l based on vapor pressure change o f the l i q u i d i n the tube. However, t h i s method was i m p r a c t i c a l over the l a r g e r temperature range d e s i r e d i n t h i s experiment . The problem o f uneven h e a t i n g over the tube was f i n a l l y overcome by w i n d i n g a uni form c o i l o f r e s i s t a n c e w i r e about the l e n g t h o f the tube . The c o i l was p r o t e c t e d 25. from contact with the tube by a layer of asbestos. An A.C. current was then passed through the c o i l to pro-vide the necessary heat. On the outside of the tube, s i x layers of 1/8" sheet asbestos were wound. In F i g . 3, #1 and #2 are diagrams of the two types of tube used. The f i r s t asbestos layer was wound when wet. The c o i l (R) was wound so that each turned buried i t -s e l f i n the asbestos layer. The outer asbestos layers were added successively, and molded about the plane ends of the tube. This l e f t the tube e n t i r e l y i n -sulated with a layer of asbestos about 1/2" thick (D), with the exception of a small aperture on the plane ends (P) to allow the l i g h t beam to pass through the tube. I t was found with t h i s system, that with a f i x e d amount of current passing through the heating c o i l , the temperature within the tube remained con-stant to within about i . l degrees centigrade. More-over, the f i e l d of view through the l i q u i d was as clear with or without the heating c o i l , i n d i c a t i n g that the temperature d i s t r i b u t i o n was f a i r l y uniform within the tube. The actual amount of heat within the c o i l was controlled by the amount of current fed to the c o i l . (See Plate I I , F i g . 2). Voltage across the c o i l I was regulated by means of a potentiometer M, and the power dissipated by the c o i l was measured by an ammeter L and voltmeter K. The amount of power neoessary to heat the volume of the l i q u i d 1°C was calculated, and from t h i s the c o i l could be set to heat'to within any small temperature range. N i s a source of steady A.C. cur-rent. Three tubes were used i n the experiment, a l l wound i n p r a c t i c a l l y the same fashion. Plate I I , F i g . 3 shows sectional views of two of them. The large tube #1 was o r i g i n a l l y intended f o r use with the a i r type of heating used by MeLeod, and has an a i r jacket (S) sur-rounding the actual c e l l . The plane p a r a l l e l windows are of pyrex. The length of the space available f o r the l i q u i d column within the tube i s 21.5 cm., and the diameter of the Pyrex windows i s four om. For examina-t i o n of the p a r a f f i n s , two smaller tubes were used. They are standard 5 cm. absorption c e l l s , manufactured by the Central S c i e n t i f i c Company. The plane p a r a l l e l windows are of "Corex" and are fused to a Pyrex body. With t h i s type of tube, there i s no i n s u l a t i n g a i r jacket. The inside length available to the l i q u i d column i n both smaller tubes was found to be 4.991 om., and the windows of both tubes were 1.50 cm. i n th i c k -ness. A l l lengths were measured by means of a t r a v e l -l i n g microscope, and the dimensions of the two smaller tubes were i d e n t i c a l to the t h i r d s i g n i f i g a n t f i g u r e . A l l the heating c o i l s were wound from #24 B. & Si oxidized "Advance" wire, which had a resistance of about 7.7 ohms per foot. The large c o i l was wound with twenty-four turns uniformly spaoed on each side of the neck of the tube, and had a t o t a l resistance of a bout 200 ohms. Both of the c o i l s wound on the smaller tube were i d e n t i c a l . Each one consisted of t h i r t y -eight turns uniformly wound over the length of the tube. With t h i s system i t was possible to obtain steady temperatures within the tube over the tempera-ture range between 1J>°C and 110°C. The actual tem-perature measurement was made by a thermometer which was t i g h t l y sealed i n the neck of the tube. Various thermometers were used, depending on the desired i n -t e r v a l of temperature measurement, (b) General Methods 1. Procedure Actual readings of the extinction angle were taken f o r p o s i t i v e and negative directions of the f i e l d strength. This gave two angles of r o t a t i o n with r e-ference to the zero angle, one i n a clockwise d i r e c t i o n , the other i n the opposite d i r e c t i o n . The t o t a l angle of rotation obtained by subtracting the vernier readings was a c t u a l l y twice the desired angle of ro-ta t i o n . This permitted a greater accuracy i n deter-mining the" actual r o t a t i o n angle, since any error oc-curing would be divided by two upon c a l c u l a t i n g the actual r o t a t i o n angle. In a l l subsequent tabulations of readings, the following notation i s used 0O » zero reference angle of the incident plane polarized ray. © v = vernier reading of the counterclockwise ro-t a t i o n angle. 9W= vernier reading of the cloekwise r o t a t i o n angle upon reversing the f i e l d d i r e c t i o n . The primes indicate that the c e l l c o r r e c t i o n r o t a t i o n has not been deducted from the angle repre-sented. I t was found necessary to take a f a i r l y large number of readings i n order to obtain consistent r e s u l t s . This was attr i b u t e d to the l a g i n the ac-comodation of the eye i n detecting s l i g h t i n t e n s i t y differences close to the extincti o n angle. In order to take a set of readings, the current was set at a p a r t i c u l a r value, and the p o s i t i o n of the ext i n c t i o n angle 6w>(when the f i e l d seen i n the analyzer ap-peared to be of uniform i n t e n s i t y ) was recorded. The current i n the c o i l s was then switohed o f f , and the posi t i o n of the extinction angle ©J,was recorded. The d i r e c t i o n of the current i n the c o i l s was then r e -versed. This process was repeated u n t i l a consistent set of readings was obtained. Usually about twenty-f i v e such readings were taken f o r each value of f i e l d strength used. During the time readings were being taken, a constant watch was maintained to ensure that neither the current i n the c o i l s nor the temperature i n the tube varied to any appreciable degree. 2. C a l i b r a t i o n A f t e r some experimentation, the optimum positions of the pole pieces f o r each tube were deter-mined. The pole piece separation when the magnet was used i n conjunction with the larger j f l tube was 22.9 cm. The separation distance f o r both small tubes was 7.22 cm. These positions were used i n a l l subsequent measurements. Before the f i e l d c a l i b r a t i o n s were made, a large number of readings were taken to determine the c e l l correction which should be applied to the sub-sequent r o t a t i o n readings. I t was decided that the steady current values to be used i n l a t e r work would be 5, 10, 15, 20, 25, and 20 amps. Then before c a l i b r a t i n g the f i e l d strength, readings of the empty c e l l r o t a t i o n were made f o r a sodium D source with the above f i e l d strengths. These readings were made f o r the three tubes. Since i t was l a t e r intended to take readings f o r four Mercury wavelengths, i t was further desirable to know the necessary c e l l r o t a t i o n cor-re c t i o n f o r these wavelengths. I t was found that no correction formula applied p a r t i c u l a r l y w e l l , and i t was necessary to take readings of the rotations f o r these wavelengths as well. Upon examination of the readings, the following f a c t s were noted. (a) A l l observed window corrections f o r c e l l s #2 and #2 were i d e n t i c a l within the l i m i t s of accuracy measured. 30. (b) The temperature change o f the c e l l windows produced a v i r t u a l l y undetec table change i n the window r o t a t i o n s , over the temperature range from l8°C to 110°C. The c o r r e c t i o n f o r the amount o f atmospheric v a i r i n the tube was worked ou t , and found to be a f a c t o r o f about .0002 degrees . S ince t h i s was beyond the l i m i t s o f exper imenta l e r r o r even f o r the h ighes t f i e l d s used t h i s c o r r e c t i o n was d i s c a r d e d . A f t e r the c e l l r o t a t i o n c o r r e c t i o n s were com-puted f o r any p a r t i c u l a r tube , i t was f i l l e d w i t h d i s -t i l l e d water and the r o t a t i o n s w i t h a sodium D source were observed f o r the s i x c o i l c u r r e n t s mentioned p r e -v i o u s l y . When the c e l l r o t a t i o n s had been ' sub t r ac t ed from these r e a d i n g s , the average magnet ic f i e l d s t r e n g t h throughout the tube f o r each cu r r en t was computed from the known Verdet cons tant o f pure water a t the appro-p r i a t e temperature . (19) The r e s u l t s o f the c e l l and f i e l d c a l i b r a t i o n s are shown i n g r a p h i c a l form i n p l a t e s I I I and I V . P l a t e I I I shows observed r o t a t i o n angle i n degrees p l o t t e d aga ins t cu r r en t i n amperes f o r A , the f-1 c e l l empty, B the #2 c e l l empty, C the $2 c e l l f i l l e d w i t h d i s t i l l e d wate r , and D the #1 c e l l f i l e d w i t h d i s t i l l e d wa te r . I t can be seen from t h i s p l a t e t ha t f o r the l a r g e r po l e sep-a r a t i o n the f i e l d s t r e n g t h i s p r a c t i c a l l y p r o p o r t i o n a l t o (19) I n t e r n a t i o n a l C r i t i c a l T a b l e s , V o l . 6, p . 425. PLATE I I I 33. the current. However, f o r higher currents, the plate shows that the pole pieces approach saturation. Each r o t -ation point on the graph represents the average of about . twenty-five separate readings of the rot a t i o n at each f i e l d strength. Plate IV shows the dispersion curves of the d e l l window ro t a t i o n f o r the various wavelengths of l i g h t used. A and B are the curves obtained when the smaller type c e l l s were used i n conjunction with currents of 30 and 20 amperes, respectively. G and D are the curves obtained when the larger tube was used i n conjunction with field-procucing currents of 30 and 20 amperes respectively. I t was not considered worth while including a l l of the r e s u l t s obtained i n c a l i b r a t i o n . The following table however, summarizes some of the r e s u l t s obtained. A l l readings were taken at a temperature within .1° of 20° C. (a) Eor 5893 , m ; • 8 / IN DEGREES Current i n Amps. .5 10 15 20 30 £5 Empty Tube #1 704 ToB 712 jLb7 726 ^ 2 1 Empty Tube #2 .08 .16 .25 .31 .4-0 .35 #lfwith d i s t i l l e d 1.74- 3.29 4.86 .4-3 9.10 7.79 #21 water 1.30 2.43 3.51 4.38 5.32 4.92 Gale. HiI0" lf#l 3.71 7.02 10.3 13.72 19.4-2 16.62 \#2 11 .9 22.4 32.3 4-0.2 48.9 45.3 (b) Dispersion Corrections ; 36234 A 5893 35779 * 35461 Empty-Tube 1 1= 20 Amps. T±l T i e YIB .25 #1 J 1= 30 Amps. .23 .26 .27 .38 Empty Tubei 1= 20 Amps. .28 .31 .33 .59 #2 J 1= 30 Amps. .30 .35 .39 .71 Each figure in the above two tables represents an average of twenty-five readings of the rotation Q which was corrected to the nearest .01 degrees. In a l l cases, the f i e ld strength H was calculated using the formula where \J = the Verdet constant of water for Sodium yellow l ight at 20° C. = .0138 minutes per Gauss-cm. £ = the length of the l iqu id column in cm. 35. IV. RESULTS (a) Trans-Decahydronapthalene 1. Verdet Constant The r o t a t i o n of trans-deoalin f o r a sodium yellow source was measured f o r the f i v e currents l i s t e d i n Table I. Table I shows the method of averaging the readings, and the f i n a l mean uncorrected r o t a t i o n 9 . The values of the Verdet constant were calculated from these, using values of c e l l window correction and f i e l d strength obtained from c a l i b r a t i o n data. Thus, S,,^, the value of the Verdet constant of trans-decalin at 21.4°C. for the sodium D l i n e was calculated from the formula J8.H The value of ©*> was not included i n the table other than as an average. I t was not necessary to use i n computing the r o t a t i o n angle. However, a close observation was kept of Qp i n a l l c a l c u l a t i o n s , with the view of detecting any signs of natural o p t i c a l a c t i v i t y which might appear. The re s u l t s of the above com-putations are summarized as follows.-I H 6' e 5 571.(3) 1.87 1.83 .0137(4) 10 702.(0) 3.56(5) 3.48 .0138(3) 15 103(3) 5.26(0) 5.14 .0139(0) 20 137(2) 6.97(5) 6.80 .0138(3) 25 166(2) 8.45(3) 8.24 .0138(4) 50 194(2) 9.83 9.56 .0137(4) 3G. TABLE I R o t a t i o n o f T r a n s - D e c a l i n w i t h Sodium Y e l l o w L i g h t (75893) T = 31.4 * . 1 ° C (a) I = 5 amps. Q0'a 3 5 9 . 6 9 ° 1.60 357.83 3.77 1.88 1.59 357.84 3.75 1.88 1.58 557.81 3.77 1.88 1.59 357.84 3.75 1.88 1.58 357.84 3.74 1.87 1.59 357.85 3.74 1.87 1.58 357.84 3.74 1.87 1.57 357.83 3.74 1.87 1.58 357.83 3.75 1.88 1.57 357.83 3.74 1.87 1.59 357.85 3.74 1.87 1.57 357.85 3.72 1.86 1.59 357.83 3.76 1.88 1.58 357.84 3.74 1.87 1.58 357.82 3.76 1.88 1.58 357.84 3.74 1.87 1.58 357.85 3.73 1.87 1.58 357.83 3.75 1.88 1.58 357.85 3.73 1.86 1.59 357.84 3.75 1.88 Mean 6' = 1.87 (b) I = 10 amps. 80= 3 5 9 . 6 9 ° ©' 3.30 356.14 7.16 3.58 3.29 356.15 7.14 3.57 3.27 356.16 7.11 3.56 3.29 356.14 7.15 3.58 3.29 356.15 7.14 3.57 3.29 356.15 7.14 3.57 3.27 356.15 7.12 3.56 3.28 356.15 7.13 3.56 3.28 356.15 7.13 3.56 3.29 356.15 7.14 3.57 3.29 356.16 7.13 3.56 3% ( D) Cont'd. TABLE I - CONT'D. 3.29 356.15 7.14 3.57 3.27 356.14 7.13 3.56 3.28 356.15 7.13 3.56 3.29 356.14 7.15 3.58 3.29 356.13 7.16 3.58 3.29 356.14 7.15 3.58 3.28 356.14 7.14 3.57 , 3.28 Mean 8 3.29 356.15 7.13 3.56 356.16 7.13 3.56 = 3.65(5)3.29 356.14 7.15 3.58 (c) I = 15 amps eo= 359.69° te> atoi -e;_, t)f 5.00 354.45 L0.55 5.28 5.00 354.45 10.55 5.28 5.00 354.44 10.56 5.28 4.99 354.44 10.55 5.28 4.98 354.45 10*53 5.26 4.99 354.44 10.55 5.28 4.98 354.46 10.52 5.26 4.98 354.46 10.52 5.26 4.99 354.45 10.54 5.27 4.98 354.46 10.52 5.26 4.98 354.44 10.55 5.28 4.97 354.45 10.52 5.26 4.97 354.45 10.52 5.26 4.96 354.47 10.49 5.24 4.98 354.46 10.52 5.26 4.98 354.45 10.53 5.26 4.97 354.46 10.51 5.26 4.98 354.45 10.53 5.26 4.98 354.46 10.52 5.26 4.97 354,47 10.50 5.25 Mean 6' s 5.26° (d) I = 20 amps g'= 359.69° o e' 6.67 352.71 13.96 6.98 6.65 352.75 13.90 6.95 6.71 352.74 13.97 6.98 6.71 352.76 13.95 6.98 6.70 352.76 13.94 6.97 6.71 352.74 13.97 6.98 6.70 352.75 13.95 6.98 3«. TABLE I - CONT'D. (d) Cont'd. &«'•> • ••• 6f-> ©' 6.71 352.76 13.95 6.98 6.70 352.76 13.94 6.97 6.72 352.76 13.96 6.98 6.71 352.74 13.97 6.98 6.70 352.76 13.94 6.97 6.70 352.74 13.96 6.98 6.70 352.74 13.96 6.98 6.72 352.76 13.96 6.98 6.70 352.76 13.94 6.97 6.69 352.74 13.95 6.98 6.70 352.76 13.94 6.97 6.70 352.75 13.95 6.98 6.6.9 352.76 13.93 6.96 Mean &'m = 6.97(5) (e) I = 25 amps. Q^- 359.69° e« 8.16 351.22 16.94 8.47 8.16 351.24 16.92 8.46 8.15 351.30 16.85 8.42 8.16 351.23 16.93 8.46 8.15 351.25 16.90 8.45 8.17 351.25 16.92 8.46 8.16 351.24 16.92 8.46 8.17 351.25 16.92 8.46 8.17 351.24 16.93 8.46 8.15 351.26 16.89 8.44 8.16 351.25 16.91 8.46 8.16 351.24 16.92 8.46 8.15 351.25 16.90 8.45 8.16 351.25 16.'91 8.46 8.17 351.25 16.92 8.46 8.14 351.26 16.88 8.44 8.15 351.26 16.89 8.44 8.14 351.27 16.87 8.44 8.16 351.24 16.92 8.46 8.17 351.24 16.93 8.46 8.16 351.25 16.91 8.46 Mean = 8.45(3)° 3,. TABLE I ,i- CONT'D. (f) I = 30 amps. 0e« 359.69° e' 9.56 349.88 19.68 9.84 9.58 349.98 19.66 9.83 9.55 349.90 19.65 9.88 9.54 349.90 19.64 9.88 9.54 349.88 19.66 9.83 9.56 349.90 19.66 9.83 9.55 349.90 19.65 9.88 9.55 349.90 19.65 9.87 9.55 349.90 19.65 9.88 9.55 349.90 19.65 9.88 9.57 349.89 19.68 9.84 9.55 349.90 19.65 9.88 9.55 349.88 19.67 9.84 9.57 349.89 19.68 9.84 9.56 349.89 19.67 9.84 9.55 349.90 19.65 9.88 9.57 349.90 19.67 9.84 9.55 349.90 19.65 9.88 9.55 349.90 19.65 9.82 9.55 349.90 19.65 9.88 9.82(7) The average v a l u e of ^ . . o b t a i n e d from these r e s u l t s was § s 1-3J?M0 ^minutes per gauss cm. The r e s u l t s appear to he c o n s i s t a n t to the t h i r d f i g u r e , s i n c e the maximum d e v i a t i o n i n any o f the va lues ob ta ined i s not g rea te r than ,.0001 minutes per gauss cm. The r e s u l t s ob ta ined by MeLeod f o r the c i s isomer o f deca l in .was _ p • ; -2. d a t= 1- ikxio minutes per gauss cm. The va lue c a l c u l a t e d on the b a s i s of the above da ta f o r P e r k i n s "molecu la r r o t a r y power", u s ing formula ( k ) , and known va lue s f o r water under s i m i l a r c o n d i t i o n s i s [M] = 9 .15 2. D i s p e r s i o n Constants , The r o t a t i o n o f t r ans d e c a l i n was observed f o r the fou r s t ronges t mercury l i n e s , a t cu r r en t s t r eng ths o f 20 and 50 amps. The Verdet cons tan t s f o r each o f these l i n e s were then c a l c u l a t e d i n the same manner as was done f o r ; A5895. The r o t a t i o n s ob ta ined are l i s t e d i n Table I I . S ince the purpose o f t h i s pa r t of the i n v e s t i g a t i o n was t o determine the absorp-t i o n f requency, by u s ing the formula ( I ) , i t was neces-sa ry f u r t h e r to c a l c u l a t e the va lue o f the product /nS a t each wavelength . T h i s computat ion was a l s o made from the read ings ob ta ined f o r ^5895. A c a l c u l a t i o n o f the term , '-..-was a l s o made f o r each wavelength (a) X6234 TABLE I I Trans Decalin Mean 9^ = 0.34° I - 20A Mean 6L/= 0.301 -30A : a*a ( Q r t » a f c ( f t - e u I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 9.20 9.29 9.29 9.28 9.28 9.30 9.30 9.31 9.29 9.29 9.30 9.31 9.31 9.30 9.29 9.29 9.28 9.29 9.27 9.29 9.29 9.28 9.28 9.28 9.28 351.26 351.28 351.29 351.29 351.29 351.30 351.29 351.30 351.30 351.30 351.30 351.30 351.30. 351.30 351.30 351.30 351.30 351.29 351.29 351.29 351.29 351.30 351.30 351.29 351.30 17.94 18.01 18.00 17.99 17.99 18.00 18.01 18.01 17.99 17.99 18i00 18.01 18.01 18.00 17.99 17.99 17.98 18.00 17.98 18.00 18.00 17.98 17.98 17.99 17.98 8.98 9.00 9.00 8.99 8.99 9.00 9.00 9.00 8.99 8.99 9.00 9.00 9.00 9.00 8.99 8.99 8.99 9.00 8.99 9.00 9.00 8.99 8.99 8.99 8.99 6.56 6.56 6.54 6.54 6.55 6.56 6.55 6.55 6.55 6.55 6.54 6.56 6*55 6.55 6.55 6.56 6.54 6.54 6.54 6.55 6.55 6.55 6.55 6.55 6.54 353.90 353.92 353.92 353.92 353.90 353.92 353.92 353.92 353.92 353.92 353.93 353.92 353.92 353.93 353.92 353.91: 353.93 353.92 353.91 353.92 353.92 353.92 353.91 353.91 353.91v 12.66 12.64 12.62 12.62 12.65 12.64 12.63 12.63 12.63 12.63 12.61 12.64 12.63 12.62 12.63 12.65 12.61 12.62 12.63 12.63 12.63 12.63 12.64 12.64 12.63 6.33 6.32 6.31 6.31 6.32 6.32 6.31 6.31 6.31 6.31 6.30 6.38 6.31 6.31 6.31 6.32 6.30 6.31 6.31 6.31 6.31 6^31 6.32 6.32 6.31 Mean e'= 8.99° Mean e = 6.3r TABLE II - CONT'D (b) !\5779 Mean 359.62° I - 20A Mean 8= 359.57° I « 30A 6 c - > fft^aboVeU eT 1 6.85 352.28 14.57 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 6.86 6.87 6.86 6.87 6.87 6.85 6.86 6.87 6.87 6*87 6.86 6.87 6.86 6.86 6.86 6.85 6.86 6.86 6.86 6.86 6.86 6.85 6.87 6.85 352.28 352.29 352.28 352.29 352.28 352.28 352.28 352.28 352.28 352.29 352.28 352.28 352.24 352.25 352.25 352.24 352.25 352.25 352.25 352.24 352.25 352.25 352.25 352.25 14.58 14 . 58 14.58 14.58 14.59 14.57 14.58 14.59 14.59 14.58 14.58 14.59 14.62 14.61 14.61 14.61 14.61 14.61 14.61 14.62 14.61 14.60 14.62 14.60 7.29 7.29 7.29 7.29 7.29 7.29 7.29 7.29 7.30 7.30 7.29 7.29 7.30 7.31 7.31 7.31 7.31 7.31 7.31 7.31 7.31 7.30 7.31 7.31 7.30 9.83 9.84 9.83 9.82 9.82 9.82 9.83 9.83 9.82 9.83 9.82 9.82 9.83 9.83 9.83 9.83 9.83 9.82 9.83 9.83 9.82 9.82 9.82 9.82 9.83 349.34 349.32 349.33 349.33 349.33 349.33 349.34 349.32 349.32 349.32 349.32 349.33 349.33 349.32 349.33 349.33 349.33 349.33 349.32 349.32 349.33 349.33 349.32 349.33 349.32 20.49 20.52 20.50 20.49 20.49 20.49 20.49 20.51 20.50 20.51 20.50 20.49 20.50 20.51 20.50 20.50 20.50 20.49 20.51 20.51 20.49 20.49 20.50 20.49 20.51 10.24 10.26 10.25 10.24 10.24 10.24 10.24 10.25 10.25 10.25 10.25 10.24 10.25 10.26 10.25 10.25 10.25 10.24 10.26 10.26 10.24 10.24 10.25 10.24 10.26 Mean 9' = 7.80 Mean ©' «. 10.25 *3. TABLE I I - CONT'D (o) ^5461 Mean 9/= 359.78° I - 20A Mean 359.78° I 30A 1 7.99 351.53 16.46 8.23 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 7.97 7.97 7.96 7.97 7.97 7.97 7.97 7.97 7.97 7.97 7.97 7.98 7.98 7.97 7.98 7.97 7.98 7.98 7.97 7.97 "7.97 7.97 7.98 7.97 351.52 351.52 351.52 351.51 351.52 351.51 351.52 351* 52 351. 52 351.52 351.52 351.52 351*52 351.52 351.51 351.51 351.53 351.52 351.52 351.52 351.51 351.52 351.52 351.52 16.45 16.45 16.44 16.46 16.45 16.46 16.45 16.45 16.45 16.46 16.45 16.46 16.46 16.45 16.47 16.46 16.45 16.46 16.45 16.45 16.46 16.45 16.46 16.45 8.22 8.22 8.22 8.23 8.22 8.23 8.22 8.22 8.22 8.23 8.22 8.23 8.23 8.22 8.23 8.23 8.22 8.23 8.22 8.22 8.23 8.22 8.23 8.22 11.33 11.32 11.33 11.33 11.32 11.33 11.32 11.33 11.30 11.30 11.32 11.30 11.31 11.31 11.31 11.31 11.32 11.32 11.31 11.31 11.31 11.32 11.32 11.31 11.33 348.20 348.21 348.20 348.22 348.21 348.20 348.19 348.19 348.21 348.19 348.21 348.21 348.21 348.19 348.19 348.20 348.20 348.21 348.21 348.21 348.21 348.20 348.21 348.21 348.20 23.13 23.11 23.13 23.11 23.11 23.13 23.13 23.14 23.09 23.09 23.11 23.09 23.10 23.12 23.12 23.11' 23.12 23.11 23.10 23.10 23;10 23.12 23.11 23.10 23.13 11.56 11.55 11.56 11.55 11.55 11.56 11.56 11.57 11.54 11.54 11.55 11.54 11.55 11.56 11.56 11.55 11.56 11.55 11.55 11.55 11.55 11.56 11.55 11.55 11.56 Mean 6' = 8.22 Mean e'- 11.55 TABLE I I - CONT'D (fl) A4558 Mean 60'. 1.77° I » 20A Mean eo= 1.77° I = 30A 1 15.14 348.52 26.62 13.31 2 15.13 348.52 26.62 13.31 3 15.13 348.52 26.61 13.31 4 15.14-348.52 26.62 13.31 5 15.12 , 348.50 26.62 13.31 6 15.14 348.50. 26.64 13.32 7 15.14 348.50 26.64 13.32 8 15.14 348.50 26.64 13.32 9 15.14 348.50. 26.64 13.32 10 15.13 348.50 26.63 13.32 11 15.13 348.49 26.64 13.32 12 15.14 348*51 26.63 13.32 13 15.14 348.52 2d.62 13.31 14 15.13 348.50 26.63 13.32 15 15.13 348.51 26.62 13.31 16 15.13 348.51 26.62 13.31 17 15.12 348.50 26.62 13.31 18 15.13 348.50 26.63 13.32 19 15.14 348.49 26.65 13.32 20 15.13 348.52 26.61 13.30 20 15.12 348.50 26.62 13;31 21 15.12 348.50 26.62 13.31 22 15.12 348.50 26.62 13.31 23 15.13 348.49 26.64 13.32 24 15.14 348.49 26.64 13.32 25 15.14 348.49 26.65 13.32 20.51 342.95 37.56 18.78 20.52 342.95 37.57 18.78 20.53 342.95 37.58 18.79 20.50 342.95 37.55 , 18.78 20.51 342.94 37.56 ' 18.78 20.51 342.95 37.56 18.78 20.51 342.95 37.56 18.78 20.51 342.95 37.56 18.78 20.50 342.95 37.55 18.78 20.52 342.95 37.57 18.78 20.50 342.95 37.55 18.78 20.50 342.95 37.55 18.78 20.52 342.95 37.57 18.78 20.51 342.95 37.56 18.78 20.51 342.95 37.56 18.78 20.50 342.95 37.55 18.58 20.50 342.96 37.,54 18.77 20.50 342.96 37.54 18.78 20.50 342.96 37.54 18.77 20.52 342.95 37.57 18.77 20.51 342.96 37.55 18.78 20*52 342.95 37.57 18.78 20.52 342.95 37.57 18.78 20.50 §42.95 37.55 18.78 20.50 342.95 37.55 18.78 20.50 342.95 37.55 18.78 Mean ©' - 13.31 Mean Q « 18.78 used. These values were plotted, and the l i n e a r r e -la t i o n s h i p obtained may be seen i n Mate V. The point corresponding to Oi 6224 shows some error was present i n measurement. This can probably be attributed to the low dispersion of the monochromator at the red end of the spectrum. The actual wavelength of the i l -lumination obtained was probably a mean between % 6234 and ?v 6907,. I f the mean of these two wavelengths i s used i n cal c u l a t i o n s , the point f a l l s on the graph. : The c h a r a c t e r i s t i c dispersion frequency was calculated by solving two of the equations obtained by substitution i n ( i ) , and was found to s u i t the r e -la t i o n s h i p . A tabular summary of the r e s u l t s follows. For I = 20.0°C - , .1°Average K 1=20 1=30 I~20 1=30 S msxlO2 xlO2 9 xior1^ 6234 5893 5779 5460 4358" . 6.15 8.77 6.80 9.57 7.12 9.98 8.'03 11.25 12.06 18.40 .0125 .0128 .0145 .0162 .0265 .0126 .0138 .0143 .0162 .0264 .0125 .0138 .0144 .0163 .0265 1.84 2.02 2.12 2.40 2.92 25.5 24.8 24.8 24.8 24.5 2.62 2.62 2.62 2.62 2.62 The values of ffi> were obtained from Mizuhara^ work (11) on the index of r e f r a c t i o n of trans decalin. I f the value of K at 6^224 i s discounted, the average value of K may be taken as K - 24.8 x 10~ 2?. Calculated value of V 0 - 2.62(2) x l O 1 ^ sec -1. Thus an absorption l i n e may be expected at about % = 1140A0 f o r decalin of temperature 20.0?C 1 .1 . 50. •51. 3. Temperature Rotation Effect Measurements of the temperature variation of the Verdet constant were extremely d i f f i c u l t to make, since the actual temperature variation was very small. It was found that there was no advantage in observing points di f fer ing by more than 6° or 7°C, since the difference in rotation produced by the strongest f ie lds was only . 0 1 ° for 2° or 3°C temperature change. Readings of the rotation for a constant current of 20 amps, were then taken for trans decalin at various temperatures. The results obtained are given in Table III . A graph was plotted of uncorrected rotation against temperature, shown i n Plate VT. The wave-length used was the mercury Green l ine (^ 5461), chosen for i t s c lar i ty and intensity. Since the rotation cor-rection is a constant factor, the uncorrected rotation i s used in plott ing. There appears to be a d is -continuity i n the temperature region of 80°C. Readings were not taken closer together in this interval , in view of the l imited accuracy of the polarimeter men-tioned above. It was thought that no signifigance could be attached to points any closer together on the graph. However, the aggregate of points on both sides of the questionable interval does point to some abrupt change in the Verdet constant in the v i c i n i t y of 80°C. It i s signifigant that the slopes of the two l ines are appreciably the same. However, there i s a shift in TABLE III 9^  5461 Trans Decalin I s 20 amps, (1) Mean _ T 9o = 0 . 0 5 ° s 1 8 . 4 ° G . (2)Mean ©<,'= 359.840 T = 26 .7°C. 6^ &L &>*3kti-& 6' 9 10 11 12 13 14 15 8.31 8.30 8.29 8.30 8.29 8,. 29 8.29 1 2 3 4 5 6 7 8. 8.'30 8.30 8.30 8.30 8.30 8.28 , 8.29' 8.30 351.90 351.90 351.90 351.90 351.90 351.91 351.90 351.91 351.90 351.91 351.89 351.90 F35i:8.9 351.91\ 351.91 " 16.41 16.39 16.39 16.40 16.39 16.38 16.39 16.39 16.40 16.39 16.41 16.40 16.39 16.38 16.39 8.20 8.00 8.20 7.97 8.20 7.99 8.20 7.99 8.20 7.99 8.19 7.99 8.19 7.99 8.19 7.99 8.20 7.98 8.19 7.99 8.20 7.99 8.20 7.99 8.19 7.99 8.19 7.99 8.19 7.99 351.68 351.67 351.68 351.67 351.67 351.68 351.68 351.68 321.68 351.68 351.68 351.67 351.67 351.68 351.68 16.32 16.30 16.31 16.31 16.31 16.31 16.31 16.31 16.30 16.31 16.31 16.32 16.31 16.31 16.31 8.16 8.15 8.16 8.16 8.16 8.16 8.16 8.16 8.15 8.16 8.16 8.16 8.16 8.16 8.16 Mean 6' = 8.20 Mean 8' « 8.16 (3) Mean 6o « 3 5 9 . 7 8 ° . . T - 38.4 (4) Mean 6.'= 3 5 9 . 8 4 ° . T = 46.1 6c* 1 7.74 351.69 2 7.76 351.68 3 7.77 351.68 4 7.77 351.68 5 7.76 351.71 6 7.78 351.50 7 7.77 351.69 8 7.76 351.70 9 7.77 351.69 10 7.77 351.70 11 7.77 351.71 12 7.78 351.71 13 7.77 351.69 14 7.76 351.69 15 7.77 351.70 Mean 0' * 16.08 16.08 16.09 16.09 16.05 16.08 16.09 16.06 16.08 16.07 16.06 16.07 16.09 16.09 16.07 8.04 8.04 8.04 8.04 8.04 8.02 8.04 8.04 8.03 8.04 8.04 8.03 8.04 8.04 8.04 8.04 7.79 7.81 7.82 7.82 7.83 7.82 7.83 7.83 7.83 7.83 7.83 7.83 7.81 7.82 7.83 351.85 351.85 351.85 351.85 351.85 351.85 351.85 351.85 351.85 351.85 351.86 351.86 351.86 251.86 351.86 Mean 9' 15.94 15.96 15.97 15.97 15.98 15.97 15.98 15.98 15.98 15.98 15.97 15.97 15.95 15.96 15.97 ='7.98 7.98 7.98 7.98 7.98 7.99 7.98 7.99 7.99 7.99 7.99 7.98 7.98 7.98 7.98 7.98 TABLE I I I - CONT'D (6) Mean ©„' = 0.08° T 58.7 8 w A6&>+3t>6ti-6t-> Q' 1 7. 77 351.90 15.87 7.94 8.00 352.25 15.77 7.88 2 7. 77 351.91 15.86 7.93 8.03 352.22 15.81 7.90 3 7. 77 351.90 15.87 7.94 8.03 352.23 15.80 7.90 4 7. 78 351.90 15.88 7.94 8.02 352.22 15.80 7.90 5 7. 78 351.89 15.89 7.94 8.01 352.22 15.79 7.90 6 7. 78 351.90 15.88 7.94 8.01 352.22 15.79 7.90 7 7. 77 351.90 15.87 7.94 8.02 352.21 15.81 7.90 .8 7. 77 351.90 15.87 7.94 8.02 352.21 15.81 7.90 9 7. 78 351.90 15.88 7.94 8.01 352.21 15.80 7.90 10 7. 77 351.90 15.87 7.94 8.01 352.21 15.80 7.90 11 7. 77 351.89 15.88 7.94 8.00 352.22 15.78 7.89 12 7. 77 351.91 15.86 7.93 8.02 352.22 15.80 7.90 13 7. 78 351.90 15.88 7.94 8.01 352.22 15.79 7.90 14 7. 77 351.89 15.88 7.94 8.00 352.21 15.97 7.90 15 7. 77 351.91 15.86 7.93 8.01 352.22 15.79 7.90 Mean = 7. 94 Mean ' = . 7.90 (7J Mean 0O' = 359.85 , (8) Mean 8 „ ' = 359.70 . T a 64.4° . . T s 68.2 1 7. 68 351.95 15.73 7.86 7.53 351.90 15.63 7.82 2 7. 69 351.96 15.73 7.86 7.51 351.89 15.64 7.82 3 7. 67 351.95 15.72 7.86 7.54 351.88 15.66 7.83 4 7. 69 351.97 15.72 7.86 7.50 351.88 15.62 7.81 5 7. 67 351.96 15.71 7.86 7.53 351.88 15.65 7.82 6 7. 67 351.96 15.71 7.86 7.51 351.88 15.63 7.82 7 7. 68 351.95 15.73 7.86 7.51 351.88 15.63 7.82 8 7. 68 351.95 15.73 7.86 7.52 351.88 15.64 7.82 9 7. 68 351.95 15.73 7.86 7.51 351.87 15.64 7.82 10 7. 68 351.96 15.72 7.86 7.52 351.88 15.64 7.82-11 7. 67 351.95 15.72 7.86 7.53 351.88 15.65 7.82 12 7. 68 351.97 15.71 7.86 7.53 351.88 15.65 7.82 13 7. 67 351.95 15.72 7.86 7.51 351.88 15.63 7.82 14 7. 68 351.95 15.73 7.86 7.53 351.88 15.65 7.83 15 7. 67 351.95 15.72 7.86 7.52 351.88 15.64 7.82 Mean 7.86 Mean ft' = 7.82 TABLE I I I - CONT'D (9) Mean ©«' = 359.69° T = 73.0°C (10) Mean 6* « 359.71° T » 78.0°C 1 7.44 a 7.45 3 7.45 4 7.45 5 7.45 6 7.45 7 7.45 8 7.44 9 7.44 10 7.45 11 7.44 12 7.44 13 7.45 14 7.44 15 7.45 351.84 351.84 351.83 351.84 351.84 351.83 351.83 351.84 351.84 351.84 351.83 351.84 351.84 351.84 351.84 Mean B 15.60 15.61 15.62 15.61 15.61 15.62 15.62 15.60 15.60 15.61 15.61 15.60 15.61 15.60 15.61 7.80 7.80 7.80 7.81 7.80 7.80 7.81 7.81 7.80 7.80 7.80 7.80 7.80 7.80 7.80 7.80 7.40 7.42 7.42 7.41 7.41 7.40 7.40 7.42 7.42 7.41 7? 40 7.40 7.40 7.-41 7.42 351.90 351.90 351.91 351.90 351.90 351.90 351.91 351.91 351.90 351*91 351.91 351.91 351.90 351.90 351.91 15.50 15.52 15.51 15.51 15.51 15.50 15.49 15.51 15.52 15.51 15.49 15.49 15.50 15.51 15.51 7.75 7*76 7.76 7.76 7.76 7.75 7.74 7.76 7.76 7.76 7.76 7.74 7.75 7.76 7.76 Mean = 7.76 (11) Mean - T 0.10° 82.8°C (12) Mean T ©o' = 0.13° o 87.8°C. l 2 3 4 5 6 7 8 9 10 11 12 13 14 15 7.81 7.81 7.83 7*81 7.83 7.82 7.83 7.82 7.83 7.81 7.82 7.81 7.82 7.81 7.81 352.42 352.41 352 .-42 352^.41 352.42 352.42 352.43 352.42 352.43 352.43 352.43 352.41 352.42 352.40 352.43 15.39 15.40 15.41 15.40 15.41 15.40 15.40 15*40 15.40 15.38 15.39 15.40 15.40 15*40 15.38 7.70 7.70 7.70 7.70 7.70 7.70 7.70 7.70 7.70 7.69 7.69 7.70 7.70 7.70 7.69 7.74 7.75 7.75 7.76 7.76 7.75 7.75 7.74 7.75 7.75 7.76 7.75 7.75 7.75 7.75 352.46 352.45 352.45 352.45 352.44 352.44 352.45 352.45 352.45 352.45 352.45 352.45 352.44 352.44 352.45 15.28 15.30 15.30 15.31 15.32 15.31 15.30 15.29 15.30 15.31 15.31 15.30 15.31 15.31 15.30 7.64 7.65 7.65 7.66 7.66 7.66 7.65 7.64 7.65 7.66 7.66 7.65 7.65 7.66 7.65 Mean 6 = 7.70 Mean©= 7.65 55. TABLE I I I - CONT'D (13) e Mean T / Cr) Go = 0.12 91.8°C (14) Mean a' » 0.20 = 99.9 °C I 2 3 4 5 6 7 7.72 7.73 7.72 7.70 7.70 7.70 7.70 8 7.70 9 7.71 10 7.70 11 7.70 12 7.70 13 7.70 14 7.70 15 7.70 352.49 352.50 352.48 352.49 352.49 352.48 352*47 352.50 352.50 352.49 352.49 352.48 352.48 352.48 352.49 15.23 15.23 15.24 15.25 15.25 15.22 15.23 15.20 15.22 15.21 15.21 15.22 15.22 15.22 15.21 7.62 7.72 352.54 7.62 7.70 352.55 7.62 7.71 352.55 7.62 7.70 352.55 7.62 7.69 352.55 7.61 7.69 352.55 7.62 7.69 352.55 7.60 7.70 352.54 7.61 7.69 352.55 7.60 7.69 352.55 7.60 7.69 352.55 7.61 7.70 352*56 7.61 7.68 352.55 7.'61 7.70 352.56 7*61 7.70 352.56 15.18 7. 59 15.15 7. 58 15.16 7. 58 15.15 7. 58 15.14 7. 57 15.14 7. 57 15.14 7. 57 15.16 7. 58 15.14 7. 57 15.14 7. 57 15.14 7. 57 15.14 7. 57 15. &3 7. 56 15.14 7. 57 15.14 7. 57 Mean JQJ'\ s 7.61° Mean 6' = 7.57° (14) Mean Go T = 0,2.0° (16) Mean = 104 t8°C T = 0.20 = 109.0 1 7. 65 352.63 15.02 7.51 7.57 352.61 14.96 7.48 2 7. 66 352.62 15.04 7.52 7.57 352.61 14.96 7.48 3 7. 65 352.63 15.02 7.51 7.57 352.62 14.95 7.48 4 7. 65 352.62 15.03 7.52 7.58 352.63 14.95 7.48 5 7. 66 352.63 15.03 7.52 7.57 352.62 14.95 7.48 6 7. 66 352.63 15.03 7.52 7.57 352.61 14.96 7.48 7 7. 65 352.63 15.02 7.51 7.57 352.61 14.96 7.48 8 7. 65 352.64 15.01 7.50 7.56 352..60 14.96 7.48 9 7. 66 352.63 15.03 7.52 7.57 352.60 14.97 7.48 10 7. 66 352.65 15.01 7.50 7.57 352.60 14.97 7.48 11 7. 64 352.63 15.01 7.50 7.57 352.61 14.96 7.48 12 7. 64 352.63 15.01 7.50 7.55 352.60 14.95 7.48 13 7. 65 352.63 15.02 7.51 7.55 352.60 .14.95 7.48 14 7. 65 352.62 15.03 7.52 7.55 352.60 14.95 7.48 15 7. 65 352.63 15.02 7.51 7.57 352.60 14.97 7.48 Mean O ' = 7.51 Mean Q =. 7.48 TABLE I I I - CONT'D (17) Mean 9© = 359.78° . T - 30.4°C. ft 1 . 7.90 351.70 16.20 8.10 2 7.91 351.72 16.19 8.10 3 7.90 351.72 16.18 8.09 4 7.92 351.71 16.21 8.10 5 7.88 351.72 16.16 8.08 6 7.89 351.71 16.18 8.09 7 7.91 351.71 16.20 8.10 8 7.91 351.72 16.20 8.10 9 7.90 351.72 16.18 8.09 10 7.91 351.71 16.20 8.10 11 7.91 351.71 16.20 8.10 12 7.89 351.70 16.19 8.10 13 7.91 351.72 16.19 8.10 14 7.89 351.69 16.20 8.10 15 7.91 351.72 16.19 8.10 Mean 9' - 8.10 the magnitude of the Verdet constant itself. The equations for the variation of the Verdet constant with temperature have been determined for the two temperature regions, and they are as follows: (i) Temperature Range 18CC to 75°C The rotation is given by 9^ = 6 (^1 - .009^ 6 (t-20)) (a.) (ii) For the Temperature Range 82°C to 110 °C The rotation is fairly closely given by 9*= 0?A(1 - .00956 (t-82°)) (r) (b) n-Octadecane and n-Docosane 1. Verdet Constants The rotations of C g^Hjg and 2^2^ 46 w e r e m e a -sured in exactly the same manner as was that of trans decalin, with the exception that, since only small samples of the pure materials were available, the shorter- tubes #2 and #3 were used. These substances are both solids at normal temperatures. Therefore, it was necessary to determine the Verdet constants at temperatures well above their melting points. In the case of Octadecane, the readings were taken at 81.0° -• 1°C. The readings obtained are exhibited in Tables IV and V. From these rotations, the values of © , the corrected rotation was obtained, and the value of Sgu0 and o»0.iwere determined for ^5893. A summary of these results follows. 5% *\ 5893 TABLE IV n-Octadecane (a) Mean 0 ' = 1.63 Mean 0o' = 1 . 6 3 (b) 5 amps. I = 1 0 amps. . I ©<•> 9<-> 1 2.93 0.19 2 2.93 0.20 3 2.94 0.23 4 2.94 0.23 5 2.92 0.21 6 2.94 0.23 7 2.92 0.21 8 2.94 0.21 9 2.93 0.22 10 2.93 0.21 11 2.92 0.20 12 2.93 0.21 13 2.93 0.21 14 2.93 0.21 15 2.93 0.20 16 2.91 0.19 17 2.92 0.21 18 2.92 0.19 19 2.93 0.21 20 2.93 0.21 21 2.92 0.19 22 2.92 0.20 23 2.92 0.20 24 2.92 0.21 25 2.93 0.19 8.74 2.73 2.71 2.71 2.71 2.71 2.71 2.73 2.71 2.72 2.72 2.72 2.72 2.72 2.73 2.72 2.71 2.73 2.72 2.72 2.73 2.72 2.72 2.71 2.74 1.37 1.36 1.36 1.36 1.36 1.36 1.36 1.36 1.36 1.36 1.36 1.36 1.36 1.36 1.36 1*36 1.36 1.36 1.36 1.36 1.36 1.36 1.36 1.36 1.36 4.15 4.15 4.16 4.14 4.14 4.15 4.14 4.15 4.15 4.15 4.16 4.16 4.16 4.15 4.16 4.15 4.15 4.16 4.14 4.14 4.16 4.15 4.15 4.15 4.15 358.98 358.99 358.99 359.01 359.00 359.00 359.01 359.01 359100 359.00 359.00 359.00 359.00 359.00 S59.01 359.00 359.00 359.00 359.00 359.00 359.01 359.01 359.00 358.99 359.00 5.17 3.15 5.17 5.13 5.14 5.15 5.13 5.15 5.15 5.15 5.16 5.16 5.16 5.14 5.15 5.15 5.15 5.16 5.15 5.14 5.15 5.14 5.15 5.16 5.15 2.58 2.58 2.58 2156 2.57 2.58 2.56 2.58 2.58 2.58 2.58 2.58 2.58 2.57 2.58 2.58 2.58 2.58 2.58 2.57 2.58 2.57 2.58 2.28 2.58 Mean 6'= 1.36 Mean 9 « 2.58 40. TABLE I V - CONT'D (c) Mean G.' = 1.63 (d) Mean ©„' = 1.63 I =15 amps. I = 20 amps. Qc^  6rt {&.»+3U%-Qc4 ft' £<3 JOWiMffo* 9 1 5.33 357.84 7.49 3.74 6.27 356.97 9.30 4.65 2 5.33 357.84 7.49 3.74 6.27 356.97 9.30 4.65 3 5.34 357.86 7.48 3.74 6.23 356.97 9.26 4.63 4 5.33 357.84 7.49 3.74 6.24 356.99 9125 4.62 5 5.33 357.86 7.47 3.74 6.23 356.97 9.26 4.63 6 5.33 357.86 7.47 3.74 6.25 356.98 9.27 4.64 7 5.32 357.85 7.47 3.74 6.25 356.95 9.30 4.65 8 5.33 357.84 7.49 3.74 6.23 356.95 9.27 4.64 9 5.35 357.86 7.49 3.74 6.25 356.95 9.30 4.65 10 5.33 357.86 7.47 3.74 6.23 356.95 9.28 4.64 11 5.32 357.87 7.45 3.72 6.24 356.97 9127 4.64 12 5.33 357.85 7.48 3.74 6.26 356.97 9.29 4.64 13 5.33 357.87 7.46 3.73 6.24 356.95 9.29 4.64 14 5.33 357.87 7.46 3.73 6.24 356.96 9.28 4.64 15 5.35 357.86 7.49 3.74 6.24 356.95 9.29 4.64 16 5.33 357.84 7.49 3.74 6.23 356.95 9.28 4.64 17 5.35 357.86 7.47 3.73 6.23 356.95 9.28 4.64 18 5.32 357.85 7.47 3.73 6.23 356.95 9.28 4.64 19 5.32 357.84 7.48 3.74 6.25 356.96 9.29 4.64 20 5.33 357.84 7.49 3.74 6.23 356.96 9.27 4.63 21 5.32 357.84 7.48 3.74 6.23 356.96 9.27 4.64 22 5.32 357.85 7.47 3.74 6.24 356.96 9.28 4.64 23 5.32 357.87 7.45 3.72 6.23 356.95 9.28 4.64 24 5.34 357.85 7.49 3.74 6.24 356.96 9.28 4.64 25 5.33 357.84 7.49 3.74 6.23 356.95 9.28 4.64 Mean 6'= 3.74 Mean 0' = 4.64 61. TABLE IV - CONT'D (e) Mean Go = 1.63 (f) Mean 1.63 I - 25 amps I 30 amps. A<-> ft' 1 6.85 356.39 10.46 5.23 7.25 355.91 11.34 5.67 2 6.82 356.34 10.48 5.24 7.26 355.91 11.35 5.68 3 6.84 356.35 10.49 5.24 7.26 355.92 11.34 5.67 4 6.83 356.37 10.46 5.23 7.28 355.93 11.35 5.68 5 6.85 356.35 10.50 5.25 7.27 355.91 11.36 5-.68 6 6.84 356.36 10.48 5.24 7.27 355.90 11.37 5.68 7 6.84 356.35 10.49 5.24 7.28 355.93 11.35 5.68 8 6.83 356.35- 10.48 5.24 7.26 355.93 11.33 5.66 9 6.82 356.35- 10.48 5.24 7.25 355.93 11.32 5.66 10 6.83 356.34 10.49 5.24 7.26 355.91 11.34 5.67 11 6.82 356.35 10.47 5.24 7.28 355.91 11.34 5.67 12 6.83 356.35 10.47 5.24 7.26 355.92 11.34 5.67 13 6.83 356.36 10.47 5.24 7.28 355.92 11.36 5-. 68 14 6.82 356.36 10.46 5.24 7.28 355.93 11.35 5.68 15 6.84 356.35 10.49 5.24 7.27 355.92 11.35 5.68 16 6.83 356.36 10.47 5.24 7.28 355.91 11.37 5.68 17 6.84 356.37- 10.47 5.24 7.25 355.90 11.35 5.68 18 6.84 356.34- 10.50 5.25 7.28 355.91 11.37 5.68 19 6.83 356.35 10.48 5.24 7.25 355.91 11.34 5.67 20 -6.83 356.36 10.47 5.24 7.26 355.91 11.35 5.67 21 6.83 356.36 10.47 5.24 7.27 355.91 11.37 5.68 22 6.85 356.36 10.49 5.24 7.26 355.93 11.33 5.66 23 6.82 356.35 10.47 5.24 7.26 355.92 11.34 5. 67 24 6.84 356.35 10.49 5.24 7.27 355.90 11.37 5.67 25 6.84 356.35 10.49 5.24 7.27 355.91 11.36 5.68 Mean 8" = 5.23 Mean & = 5.67 TABLE V n-Docosane 5893 a. (a) Mean 0* = 1.65 I =10 amps, (b) Mean 90=1.65 I s amps 6rt (6w43^ -ck ft" fa-) fow*3rt-ft-7 ft' 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 4.27 4.29 4.25 4.27 4.30 4.30 4.29 4.29 4.28 4.29 4.29 4.29 4.29 4.29 4.28 4.29 4.30 4.28 4.28 4.27 4.27 4.27 4.29 4.28 4.29 -359,. 07 359.09 359.05 359.05 359.05 359.07 359.07 359..05 359.06 359.07 359.07 359.07 359.06 359.07 359.07 359.07 359.05 359.05 359107 359.05 359.07 359.06 359.05 359.07 359.07 5.20 5.20 5.20 5.22 5.25* 5.23 5.22 5.24 5.22 5.22 5.22 5.22 5.23 5.22 5.21 5.22 5.25 5.23 5.21 5.22 5.20 5.21 5.24 5.21 5.22 2.60 2.60 2.60 2.61 2.62 2.62 2.61 2.62 2.61 2.61 2.61 2.61 2.62 2.61 2.60 2.61 2.62 2.62 2.60 2.61 2.60 2.60 2.62 2.60 2.61 5.45 357.87 5.450 357.85 5.43 357.85 5.44 5.43 5.44 5.44 5.43 5.45 5.44 5.44 5.44 5.45 5.45 5.44 5.44 5.44 5.43 5.43 5.45 5.45 5.44 5.43 5.45 5.45 357.87 357.85 357.87 357.88 357.87 357.85 357.86 357.85 357.87 357.87 357.87 357.88 357.87 357.87 357.88 357.88 357.87 357.85 357.88 357.88 357.86 357.86 7.58 7.58 7.58 7.57 ,7.58 7.57 7.56 7.56 7.60 7.58 7.59 7.57 7.58 7.58 7.56 7.57 7.57 7.55 7.55 7.58 7.60 7.57 7.55 7.59 7.59 3.79 3.79 3.79 3.78 3.79 3.78 3.78 3.78 3.80 3.79 3.80 3.78 3.79 3.79 3.78 S.78 3.78 3.78 3.78 3.79 3.80 3.78 3.78 3.79 3.79 Mean e' a 2.61 Mean 6' - 3.78 TABLE V - CONT'D (c )Mean I ft.' =1.65 = 20 amps. (d) Mean I © o = 1.65 = 25 amps. e« {fttf^ ?fap>eiv ft' e'« ft' i 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 6.32 6.31 6.32 6.32 6.31-6.33 6.33 6.32 6.32 6.33 6.34 6.33 6.33 6.34 6.34 6.33 6.33 6.34 6.32 6.34 6.33 6.34 6.33 6.34 6.33 356.92 356.92 356.93 356.93 356.93 356.93 356.94 356.95 356.94 356.94 356.i.4. 356.95 356-. 94 356V94 356"'. 94 356.95 356.95 356.95' 356.95 356.95 356.95 356.95 356'. 94 356.94 356.95 9.40 9.39 9.39 9.39 9.38 9.40 9.39 9.37 9.38 9.38 9.40 9.38 9.39 9.40 9.40 9.38 9.38 9.39 9.37 9139 9.38 9.39 9.39 9.40 9.38 4.70 4.70 4.70 4.70 4.69 4.70 4.70 4.68 4.69 4.70 4.70 4.69 4.70 4.70 4.70 4.69 4.69 4.70 4.68 4.70 4.69 4.70 4.70 4.70 4.69 6.95 6.95 6.95 6.95 6.96 6.94 6.95 6.94 6.93 6.94 6.95 6.95 6.95 6.95 6.94 6.94 6.94 6.93 6.93 6.93 6.94 6.94 6.95 6.94 6.94 356.33 356.35 356.35 356.35 356.35 356.35 356.35 356.34 356.34 356.35 356.34 356.35 356.34 356.34 356.35 356.34 356.34 356.35 356.34 356.35 356.35 356.35 356.34 356.35 356.35 10.62 10.60 10.50 10.60 10.61 10.59 10.60 10.60 10.59 10.59 10.61 10.60 10.61 10.61 10.59 10.60 10.60 10.58 10.59 10.58 10.59 10.59 10.61 10.59 10.59 5.31 5.30 5.30 5.30 5.30 5.30 5.30 5.30 5.30 5.30 5.30 5.30 5.30 5.30 5.30 5.*30 5.30 5.29 5.30 5.29 5.30 5.30 5.30 5.30 5.30 Mean 8 - 4.69 Mean @' = 5.50 TABLE V - CONT'D (e) Mean ©0' = 1.65 I =30 amps. 1 7.41 355.89 11.52 5.76 2 7.43 355.91 11.52 5.76 3 7.41 355.92 11.53 5.76 4 7.40 355.89 11.51 5.76 5 7.40 355.91 11.49 5.74 6 7.41 355.90 11.51 5.76 7 7.40 355.91 11.49 5.74 8 7.42 355.92 11.50 5.75 9 7.41 355.90 11.51 5.76 10 7.41 355.92 11.49 5.74 11 7.41 355.91 11.50 5.75 12 7.40 355.92 11.48 5.74 13 7.40 355.90 11.51 5.76 14 7.41 355.90 11.51 5.76 15 7.41 355.90 11.51 5.76 16 7.40 355.91 11.49 5.74 17 7.40 355.92 11.48 5.74 18 7.42 355.91 11.51 5.76 19 7.41 355.90 11.51 5.7 6 20 7.41 355.90 11.51 5.76 21 7.40 355.90 11.50 5.75 22 7.40 355.90 11.50 5.75 23 7.40 355.89 11.51 5.76 24 7.41 355.90 11.51 5.76 25 .7.41 355.90 11.51 5.76 Mean ©' = 5.75 I HxlO" 2 Octadecane Docosane e X ° e 5 3.71 1.28 .0128(9) 10 7.02 2.40 .0128(9) 2.44 .0131(3) 15 10.3 3.49 .0129(8) 3.54 .0131(6) 20 13.7 4.32 .0129(0) 4.38 .0130(8) 25 16.6 4.89 .0129(6) 4.95 .0131 3) 50 19.4 5.28 .0129(7) 5.38 .0131(6) The r e s u l t s when given to three s i g n i f i c a n t figures are: Verdet constant of n-Octadecane = 1.29 x 10~2 minutes per gauss om. Verdet constant of n-docosane « 1.31 x 10"*2 minutes per gauss om. As i n the case of trans decalin, the r e s u l t s appear to he quite consistent, since at no time i s the deviation greater than .0001 minutes per gauss cm. Since the rotations were observed to three s i g n i f i c a n t figures only, t h i s i s to be expected. On the basis of the data, the value of Perkins "molecular rotatory power", using formula (k) was calculated as was done f o r trans decalin. The values obtained compared with the t h e o r e t i c a l values obtained by Perkin and are shown below. n-Octadecane n-Docosane Calculated Experimental Calculated Experimental M 18.90 18.59 22.96 22.71 Deviation ( + ).31 (+).25 c i s decalin . trans decalin Calculated Experimental Calculated Experimental [M] 8.93 8.63 8.93 9.15 Deviation (+).30 (-).22 The table includes the values obtained f o r trans decalin, and those obtained by MeLeod f o r c i s decalin. Eor the lower members of the p a r a f f i n series, j?erkin has obtained good agreement. However, his pre-di c t i o n s f o r various heavier hydrocarbons have been consistently i n error by a fac t o r of about .3. The above table shows t h i s i s the case f o r the molecules examined. 2. Dispersion Constants The procedure i n determining the dispersion constants was i d e n t i c a l to that used f o r those of trans decalin. The rotations of both octadecane and docosane were observed f o r the four stronger Mercury l i n e s , at current strengths of 20 and 30 amps. The Verdet con-stants f o r each of these wavelengths were calculated as i n the previous case. The actual rotations observed f o r the wavelengths may be found i n Tables VT and VII. The values of the indices of r e f r a c t i o n f o r the r e -quired wavelengths f o r docosane and octadecane, however, have not been measured. Accurate determinations of the required indices of r e f r a c t i o n , however, were obtained by calculations made from the following formula, which was determined by Kurtz and Ward, and found to be ac-TABLE VT n-Octadecane (a) A 6254 (1) Mean 6» I = 6.90 = 20 amps. (2) Mean I 9w &U loWfco-£A 9' 9i-Q = 6.90 a 30 amps. 1 4.80 2 4.81 3 4.80 4 4.81 5 4.81 6 4.81 7 4.79 8 4.81 9 4.80 10 4.79 11 4.80 }2 4.79 13 4.79 14 4.80 15 4.82 356.91 356.92 356.91 356.92 356.92 356.92 356.91 356.91 356.92 356.90 356.90 356.91 356.92 356.91 356.92 Mean &' » I 7.89 3.94 5.76 355.97 9.79 4.90 7.89 3.94 5.78 355.99 9.79 4.90 7.89 3294 5.78 355.98 , 9.80 4.90 7.89 3.94 5.76 355.98 9.78 4.89 7.89 3.94 5.76 355.96 9.80 4.90 7.89 3.94 5.75 355.96 9.79 4.90 7.88 3.94 5.76 355.97 9.79 4.90 7.90 3.95 5.77 355.96 9.81 4.90 7.88 3.94 5.76 355.98 9.78 4.89 7.89 3.94 5.76 355.97 9.79 4.90 7.90 5.95 5.76 355.97 9.79 4.90 7.88 3.94 5.77 355.98 9.79 4.90 7.87 3.94 5.75 355.98 9.77 4.88 7.89 3.94 5.77 355.99 9.78 4.88 7.90 3.95 5.77 355.99 9.79 4.90 ,94 Mean ©' = 4.89 (b) A5779 (1) Mean Q'0 = 0.19 (2) Mean I . 2 0 amps. I e'o» 9c-> v&wiik-eU & flisa © 6 =0.19 3 30 amps. fr-? {f&*sttvert ft' 1 5.02 355.39 2 5.01 355.40 3 5.01 355.40 4 5.01 355.40 5 5.00 355.40 6 5.01 355.41 7 5.01 355.41 8 5.02 355.40 9 5.01 355.39 10 5.02 355.40 11 5.00 355.40 12 5.01 355.39 13 5.02 355.40 14 5.01 355.40 15 5.01 355.39 9.63 9.61 9.61 9.61 9.60 9.60 9.60 9.62 9.62 9.62 9.60 9.62 9.62 9.61 9.62 4.82 4.80 4.80 4.80 4.80 4.80 4.80 4.81 4.81 4.81 4.80 4.81 4.81 4.80 4.81 6.06 6.08 6.07 6.08 6.08 6.08 6.08 6.09 6.08 6.09 6.10 6.09 6.09 6.09 6.09 Mean = 4.81 354.28 354.29 354.30 354.30 354.29 354.31 354.31 354.29 354.30 354.30 354.30 354.30 354.30 354.29 354.29 Mean 11.78 11.79 11.77 11.78 11.79 11.77 11.77 11.80 11.78 11.79 11.80 11.79 11.79 11.80 1.1.80 = 5.90 5.89 5.90 5.88 5.89 5.90 5.88 5.88 5.90 5.89 5.90 5.90 5.90 5.90 5.90 5.90 (o) A 5461 TABLE VI - CONT'D (1) Mean 0O' = 0.19 = 20 amps, . - I 1 5.63 2 5.63 3 5.63 4 5.64 5 5.63 6 5.64 7 5.64 8 5.63 9 5.63 10 5.63 11 5.65 12 5.64 13 5.64 14 5.64 15 5.64 (2) Mean 0D - 0.30 I » 30 amps. 354.75 354.75 354.74 354.76 354.75 354.76 .354.77 354.76 354.76 354.77 354.76 354.76 354.77 354.77 354.75 10.88 10.88 10.89 10.88 10.88 10.88 10.87 10.87 10.87 10.86 10.89 10.88 10.87 10.87 10.88 5.44 5.44 5.44 5.44 5.44 5.44 5.44 5.44 5.44 5.43 5.44 5.44 5.44 5.44 5.44 6.87 6.88 6.89 6.88 6.89 6.87 6.87 6.88 6.87 6.89 6.89 6,88 6.89 6.90 6.89 Mean 0 / a 5.44 353.70 353.70 353.69 353.68 353.70 353.69 353.70 353.71 353.70 353.69 353.70 353.69 353.70 353.69 353.70 Mean 8 ' 13.17 13.18 13.20 13.20 13.19 13.18 13.17 13.17 13.17 13.20 13.19 13.19 13.19 13.21 13.19 - 6.60 6.58 6.59 6.60 6.60 6.60 6.59 6.58 6.58 6.58 6.60 6.60 6.60 6.60 6.60 6.60 4358 (1) Mean I = 3.33 a 20 amps. (2) Mean I = 3.33 = 50 amps. 1 12.20 354.48 2 12.20 354.50 3 12.23 354.50 4 12.23 354.50 5 12.22 354.48 6 12.20 354.49 7 12.21 354.48 8 12.19 354.48 9 12.19 354.48 10 12.22 354.48 11 12.20 354.48 12 12.22 354.48 13 12.22 354.50 14 12.20 354.50 15 12.20 354.48 Mean 17.72 17.70 17.73 17.73 17.74 17.71 17.73 17.71 17.71 17.74 17.72 17.74 17.72 17.70 17.72 8.86 8.86 8.85 8.86 8.86 8.87 8.86 8.86 8.86 8.86 8.87 8.86 8.87 8.86 8.85 8.86 14.26 14.27 14.27 14.25 14.25 14.27 14.27 14.25 14.25 14.25 14.27 14.26 14.26 14.27 14.26 M 352.47 352.49 352.50 352.48 352.50 352.48 352.50 352.50 352.48 352.48 352.50 352.50 352.49 352.49 352.48 ean 8 21.79 21.78 21.77 21.77 21.75 21.79 21.77 21.75 2i.77 21.77 21.77 21.76 21.77 21.78 21.78 10.90 10.89 10.88 10.88 10.88 10.90 10.88 10.88 10.88 10.88 10.88 10.88 10.88 10.89 10.89 = 10.88 TABLE VII  n-Docosane (a) A 6234 (1) Mean Go = 1.35 (2) Mean © o = 1.35 I = 20 Amps. I =30 amps. 9M fe***o|-$» i 5. 65 356.95 8.70 4.35 6.55 356.08 10.47 5.24 2 5. 64 356.96 8.68 4.34 6.57 356.09 10.48 5.24 3 5. 64 356.95 8.69 4.34 6.57 356.08 10.49 5.24 4 5. 65 356.94 8.71 4.36 6.55 356.08 10.47 5.24 5 5. 64 356.95 8.69 4.34 6.55 356.10 10.45 5.24 6 5. 65 356.96 8.69 4.34 6.57 356.09 10.48 5.24 7 5. 64 356.95 8.69 4.34 6.55 356.08 10.47 5.24 8 5. 66 356.95 8.71 4.36 6.54 356.08 10.46 5.23 9 5. 64 356.97 8.67 4.34 6.57 356.09 10148 5.24 10 5. 66 356.96 8.70 4.35 6.55 356.09 10.46 5.23 11 5. 64 356.94 8.70 4.35 6.55 356.09 10.46 5.23 12 5. 64 356.96 8.68 4.34 6.56 356.10 10.46 5.23 13 5. 66 356.95 8.71 4.36 6.57 356.10 10.47 5.24 14 5. 64 356.94 8.70 4.35 6.55 356.10 10.45 5.22 15 5. 64 356.95 8.69 4.34 6.57 356.09 10.48 5.24 Mean 0' = 4.35 Mean Q'= 5.23 (b) ? l 5779 (1) Mean I 0o = 359.71° - 20 amps, (2) Mean - I Go = 359.71° s 30 amps. 1 4.58 354.84 9.74 4.87 5.68 2 4.58 354.80 9.78 4.89 5.70 3 4.59 354.81 9.78 4.89 5.68 4 4.58 354.79 9.79 4.90 5.69 5 4.58 354.79 9.79 4.90 5.69 6 4.57 354.79 9.78 4.89 5.68 7 4.59 354.81 9.78 4.89 5.68 8 4.59 354.79 9.80 4.90 5.70 9 4.59 354.81 9.78 4.89 5.68 10 4.58 354.81 9.77 4.88 5.70 11 4.60 354.79 9.81 4.90 5.70 12 4.59 354.80 9.79 4.90 5.68 13 4.59 354.81 9.78 4.89 5.68 14 4.59 354.80 9.79 4.90 5.69 15 4.60 354.79 9.81 4.90 5.68 353.73 353.73 353.72 353.71 353.71 353.72 353.72 353.73 353.73 353.72 353.72 353.71 353.73 353.72 353.73 11.95 11.97 11.96 11.98 11.98 11.96 11.96 11.97 11.95 11.98 11.98 11.97 11.95 11.97 11.95 5.98 5.98 5.98 5.99 5.99 5.98 5.98 5.98 5.98 5.99 5.99 5.98 5.98 5.98 5.98 Mean ft7 a 4.89 Mean 0 ' = 5.98 70. (b) A 5461 TABLE VII - CONT'D (1) Mean Go = 358.92 (2) Mean 8» = 358.92 I = 20 amps. I = 30 amps. e ( « 9 w 0' eU 6' 1 4.39 353.44 10.95 5.48 5.64 352.17 13.47 6.74 2 4.39 353.43 10.96 5.48 5.64 352.17 13.47 6.74 3 4.39 353.44 10.95 5.48 5.65 352.18 13.47 6.74 4 4.39 353.43 •10.96 5.48 5.64 352.18 13.46 6.73 • 5 4.40 353.42 10.98 5.49 5.64 352.18 13.47 6.73 6 4.38 353.42 10.96 5.48 5.65 352.17 13.48 6.74 7 4.39 353.43 10.96 5.48 5.63 352.17 13.46 6.73 8 4.39 353.43 10.96 5.48 5.65 352.18 13.47 6.74 9 4.39 353.43 10.96 5.48 5.64 352.18 13.46 6.73 10 4.39 353.43 10.96 5.48 5.65 .352.18 13.47 6.74 11 4.39 353.42 10.97 5.48 5.64 352.18 13.46 6.73 12 4.39 353.44 10.95 5.48 5.64 352.18 13.46 6.73 13 4.40 353.43 10.97 5.48 5.65 352.17 13.48 6.74 14 4.40 353.43 10.97 5.48 5.64 352.19 13.45 6.72 15 4.39 353.43 10.96 5.48 5.64 352.17 13.47 6.74 Mean 0' = 5.48 ' Mean 0' r 6.73 (d) 4358 (1) Mean 9„' . I 0w _ l 10-. 95 2 10.95 3 10.98 4 10.99 5 10.97 6 10.98 7 10.96 8 10.97 9 10.98 10 10.98 11 10.95 12 10.95 13 10.95 14 10.98 15 10.96 - 358.92° = 20 amps. (2) Mean I = 358.92° = 30 amps. 9c-) fo»+aD3r-3n Q7 Mean 352.92 352.92 352.95 352.93 352.93 352.95 352.93 352193 352.93 352.92 352.93 352.94 352.95 352.94 352.94 6' = 18.03 18.03 18.03 18.06 18.04 18.03 18.03 18.04 18.05 18.06 18.02 18.01 18.00 18.04 18.02 9.01 9.00 9.02 9.02 9.03 9.02 9.02 9.02 9.02 9.02 9.03 9.01 9.00 9.00 9.02 9.01 12.91 12.89 12.90 12.89 12.91 12.90 12.89 12.90 12.91 12.91 12.89 12.91 12.89 12.89 12.90 351.02 351.00 351.00 351.02 351.02 351.01 351.02 351.02 351.01 351.00 351.01 351.02 351.02 351.02 351.02 Mean Q' -21.89 21.89 21.90 21.87 21.89 21.89 21.87 21.88 21.90 21.91 21.88 21.89 21.87 21.87 21.88 10. 10.94 10.94 10.95 10.94 10.94 10.94 10.94 10.94 10.95 10.96 10.94 10.94 10.94 M).94 10.94 94 curate f o r a l l the normal p a r a f f i n series of hydro-carbons. (The average deviation of the normal paraf-f i n indices calculated by thi s formula was .0002.) / Y 1 a_ 1 _ <t% ic A- If-8°U x 103>  where: n = r e f r a c t i v e index at temperature t and pres-sure p. M = molecular weight i n grams per mole. F = frequency constant f o r the p a r a f f i n series = 3*2313 for normal p a r a f f i n s . k «• the apparent number of dispersion electrons per formula bond = I.076O f o r normal paraf-f i n s . d* ** density at temperature t and pressure p. b =• number of formula bonds per molecule Y = frequency of the l i g h t r efracted = 2*9986 x 101Q om.seo"1 wavelength cm. The value of the hypothetical l i q u i d density 20 d£ was calculated by a method suggested by L i p k i n and Kurtz (17), using a r e l a t i o n between c o e f f i c i e n t of ex-pansion and molecular weight. The actual density data was obtained from Seyer's (13) r e s u l t s on the density of the higher numbered p a r a f f i n s . Referring to the equation (o), the product/ft* f o r each wavelength was calculated, including the wavelength of the sodium D l i n e . The term „ —- was calculated, using a value of ( V* ) calculated from the Kurtz formula. The 1Z. two following tables summarize the calculations. (I) n-octadecane T -78.8 ± .1 >\ in A ° - * 6234 5893 5779 5460 4? 58 VxlO" 1 4 4.81 5.09 5.19 5.49 6.88 e 1=20 3.67 4.32 4.43 5.08 8.27 . 1=30 4.50 5.2? 5.45 6.16 10.14 3 x 102 1=20 1.09(4) 1.29(0) 1.32(1) 1.5K7) 2.47(0) 1=30 1.10(6) 1.29(7) 1.32(1) 1.51(5) 2.49(2) Average S*x 10* 1.10 1.29 1.32 1.52 2.48 calculated 1.41(8) 1.41(9) 1.42(0) 1.42(1) 1.43(8) ns xlO 2 1.56 1.83 1.88 2.15 3.54 32 3.26 3.67 3.74 4.32 7.07 KxlO"^0 4.80 4.99 4.98 4.98 5.01 2.941 2.941 2.941 2.941 2.941 From this (disregarding results for A6234), the average value of K is K = 4.99 x 10^°, and the average value of the natural dispersion frequency at a temperature of 78.8°C is V© - 2.94 x lO 1^ sec"1. In order to demonstrate the validity of equa-tion (o), a graph of log (ris) vs log (—^ ,t) was (V.^-Vv^ plotted for both compounds and may be seen in Plates VII and VIII. IS, (ii) n-Docosane T = 80.1 ± ' . l o c . A in A° —» >6234 >5893 A2779 ^ 2460 *4258 YxlO-14 4.81 2.09 2.19 2.49 6.88 e \ 1=20 4.07 4.28 4.56 5.12 8.42 v. 1=30 4.84 2.22 5.58 6.29 10.22 0 1=20 1.21(4) 1.21(2) 1.26(2) 1.52(0) 2.5K6) i x I U 1=30 1.21(7) 1.21(6) 1.27(2) 1.54(6) 2.50(8) Average 3A x 102 1.21 1.21 1.26 1*54 2.51 Calculated 1.420 1.422 1.424 1.425 1.422 /ns* i o 2 1.72 1.8? 1.94 2.19 2.60 3.28 2.69 2.85 4.25 7.11 K x 10~50 4.797 2.02 5.02 5.04 5.05 (Vo+c^)xl0*15 .2.92(8) 2.92(8) 2.92(8) 2.92(8) 2.92(8) The average value of K is K = 5.04 x 10^°. The natural dispersion frequency at a temperature of 80.1 i .1°C is (V0+^) = 2.928 x lO 1^. 2. Temperature Rotation Effect As in the case of trans-decalin, the tempera-ture-rotation effect of n-octadeaane was investigated. It was not thought profitable to study the effect in n-doeosane, since the high melting point of the material left only a small temperature range over which the variation might be investigated. The rotations obtained for the temperature-rotation effect are given in Table VTII, along with the corrected rotations at these tem-peratures. The results so obtained were plotted in graphical form (See Mate IX). The eurve so obtained TABLE VIII n-Octadecane % 5461 - 20 amps, (a) Mean 6' = 359.62 T = 31.3 UC. (b) Mean 6* = T 359.62 39.8°C, 1 2 8 4 5 6 7 8 9 10 11 12 13 14 15 .22 .22 .23 .22 .23 .22 .22 .23 .22 .22 .23 .23 .22 .22 .22 Mean 353.86 353.87 353.86 353.87 353.88 353.87 353.88 353.88 353.88 353.88 353.88 353.87 353.87 353.88 353.88 8' = 11.36 11.35 11.37 11.35 11.35 11.35 11.34 11.35 11.34 11.34 11.35 11.36 11.35 11.34 11.34 5. 61' 5.68 5.68 5.68 5.68 5.68 5.68 5.67 5.68 5.67 5.67 5.68 5.68 5.68 5.67 5.67 5.21 5.22 5.21 5.20 5.21 5.21 5.21 5.22 5.21 5.21 5.21 5.21 5.21 5.21 5.21 353.99 353.99 353.99 353.98 353.98 353.99 353.98 353.99 353.98 353.99 353.99 353.98 353.99 353.99 353.99 11.22 11.23 11.22 11.22 11.22 11.22 11.23 11.23 11.23 11.20 11.22 11.23 11.22 11.22 11.22 5.61 5.62 5.61 5.61 5.61 5.61 5.62 5.62 5.62 5.60 5.61 5.62 5.61 5.61 5. 61 Mean 6'r 5.67* , . Mean Id) T 0/ = 359.62 = 60.6 i \ Mean 06' = 359.62 T = 49.8°C i 2 3 4 5 6 7 5. 5. 5. 5. 5. 5. 5. 8 5. 9 5. 10 5. 11 5. 12 5. 13 5. 14 5. 15 5. 13 13 13 14 13 14 13 13 14 13 13 13 13 13 13 354.07 354.06 354.07 354.06 354.07 354.05 354.06 354.06 354.06 354.06 354.06 354.05 354.06 354.07 354.05 11.06 11.07 11.06 11.08 11.06 11.09 11.07 11.07 11.08 11.07 11.07 11.08 11.07 11.06 11.08 5.53 5.54 5.53 5.54 5.53 5.54 5.64 5.54 5.54 5.54 5.54 5.54 5.54 5.53 5.54 5.08 5.09 5.09 5.09 5.09 5.10 5.10 5.11 5.10 5.10 5.10 5.10 5.09 5.10 5.09 Mean ft' s 5.54* 354. 354. 354. 354. 354. 354. 354. 354. 354. 354. 354. 354. 354. 354. 354. Mean 10 09 10 10 10 09 10 09 09 09 10 09 09 10 10 10.98 10.99 10.99 10.99 10.99 11.01 11.00 11.02 11.01 11.02 11.00 11.01 11.00 11.00 11.01 9' = 5.49 5.50 5.50 5.50 5.50 5.50 5.50 5.51 5.50 5.50 5.50 5.50 5.50 5.50 5.50 .50° 77 TABLE V I I I - CONT'D (e) Mean 9l = 359.63 (f) Mean 6B' _ 0.29 T = 69.3°G. T - 79.5°C. 0w e' 6 H 1 5.07 354.13 10.94 5.47 5.63 354.75 10.88 5.44 2 5.05 354.11 10.94 5.47 5.63 354.74 10.89 5.44 3 5.06 354.13 10.93 5.46 5.64 354.76 10.88 5.44 4 5.07 354.11 10.95 5.48 5.64 354.76 10.88 5.44 5 5.07 354.13 10.94 5.47 5.63 354.75 10.88 5.44 6 5.05 354.12 • 2.0.93 5.46 5.64 354.76 10.88 5.44 7 5.07 354.12 10.95 5.48 5.64 354.77 10.87 5.44 8 5.06 354.13 10.93 5.46 5.63 354.76 10.87 5.44 9 5.06 354.12 10.94 5.47 5.63 354.77 10.87 5.44 10 5.06 354.13 10.93 5.46 5.63 354.77 10.86". 5.43 11 5.05 354.12 10.93 5.46 5.65 354.76 10.89 5.44 12 5.06 354.12 10.94 5.47 5.64 354.76 10.88 5.44 13 5.07 354.12 10.95 5.48 5.64 354.77 10.87 5.44 14 5.07 354.13 10.94 5.47 5.64 354.77 10.87 5.44 15 5.06 354.13 10.93 5.46 5.64 354.75 10.89 5.44 Mean © ' = 5.47° Mean 0 = 5.44° (g) Mean Q« s 359.64 T = 90.2°C. 1 4.99 354.16 10.83 5.42 2 4.99 354.16 10.83 5.42 3 4.98 354.16 10.82 5.41 4 4.98 354.15 10.83 5.42 5 4.97 354.15 10.82 5.41 6 4.98 354.16 10.82 5.41 7 4.97 354.15 10.82 5.41 8 4.97 354.16 10.81 5.40 9 4.98 354.16 10.82 5.41 10 4.98 354.16 10.81 5.40 11 4.97 354.15 10.82 5.41 12 4.97 354.15 10.82 5.41 13 4.97 354.15 10.82 5.41 14 4.97 354.16 10.81 5.40 15 4.97 354.15 10.82 5.41 Mean Q' - 5.41* PLATE IX - Normal Octadecane o 1 * 1 fl was of a nature that might be expected f o r t h i s type of compound, and l i t t l e i n d i c a t i o n of i r r e g u l a r i t y may be seen i n the r e s u l t s . The equation giving r o t a t i o n . of n-octadecane at a temperature t within the range 30° to 110°C was determined from the graph, and was found to be: § 4 = .0151 (1 - 6.77xlO~4t -1- ,833xl0- 6t 2) (s) where S^ . i s the Verdet constant of n-octadecane at a temperature t°C. simmer AND CONCLUSIONS (a) Summary The following table summarizes the data obtained regarding the magneto-optic constants of trans-decalin, n-octadecane and n-docosane. Wherever possible, the presumed accuracy of the determination has been i n -dicated. In most cases the re s u l t s obtained were con-sistent to the accuracy predicted by appraisal of measuring methods. Compound Constant Experimental Value Presumed Aoouraoy 1. Trans Decalin . ( D ) £1*6234) 2. n-Octadecane 3. n-Docosane *JA5460) $4*4558) K LM 3 39,4 D ) S*KJA6234) W*5779) W * 5 4 6 0 ) <*»•©) 1° 5«ft.i( © ) 5,7/(^6234) 1*5779) VlU546o) ^»4>4358) C<f<>«-0)?6.| K 1.385 X 10" 2 + mm 1.255 X 10-2 + 1.434 X 10-2 + 1.626 X 10-2 + 2.648 X 10-2 + 2.63 X lQl* 34.8 x 10-2? + 9.15 1.289 X 10-| 1.100 X 10-2 + 1.321 X 10-2 + 1.516 X 10-2 + 2.941 X 1015 2.925 X 1015 2.925 X 1015 IUUW, .2% 4.99 x 18.59 1.311 1.216 1.367 1.538 2.512 2.93(8) .01534 . 2.92(3) x 1015 5.03 x 1030 x X X X X 10-2 10-2 10-2 10-2 10-2, x 10l^ x 1015 .2% .2% 1 .00005 ± .00005 + .00005 i .00005 1 .00005 , e ± .005x1015 .2% In a l l cases the actual calculations were car r i e d to four s i g n i f i g a n t f i g u r e s , and then corrected to three as shown i n the above table. (b) Conclusions 1. Trans-Decalin I t oan be seen that the Verdet constant of the trans isomer of deca l i n i s considerably higher than that of the c i s isomer. This i s unusual, since the contribution of an orientation ohange within the molecule to the Verdet constant i s not usually as large. I f the molecular rotary power of the two isomers i s compared to that calculated by Perkin f o r decahydro-napthalene, the deviations are seen to be of approxi-mately the same magnitude, but opposite i n sign. This would indicate that i n the case of decahydronapthalene the Perkin rule i s not a good approximation. While t h i s r u l e applies very well to the p a r a f f i n hydro-carbons, i t has been found by other investigators that the r u l e i s consistently i n error by a fact o r of about ±0.3. Thus i t appears that, although s t r u c t u r a l ad-dition s to the molecule have been reasonably well ac-counted f o r by the Perkin r u l e , a fact o r remains to be considered which i s contributed by the actual orienta-t i o n of the various groups within the molecule. How-ever, the consistency of the deviation from the Perkin rule indicates that the molecular rotatory power i s a reasonably,characteristic property of the molecule. The r e s u l t s of the dispersion of the Verdet constant of trans-decalin indicates that, within the accuracy of the experiment, the following equation may be used to account f o r the v a r i a t i o n of the Verdet constant with wavelength f o r the range of frequencies close to Vo. v V . ' - v ' V - (t) Since Vo i s the frequency of the dispersion electrons, i t i s to be expected that an absorption l i n e may be found f o r trans-decalin i n the frequency region V Q = 2.63 x lol^ sec.**-*-. This corresponds to a wave-length of ^  » 1140A0, well i n the u l t r a - v i o l e t region of the spectrum, beyond the absorption l i m i t s of atmospheric a i r . A v e r i f i c a t i o n of t h i s would be d i f -f i c u l t to obtain. I t was hoped that the dispersion frequency could have been measured over a v a r i a t i o n of tempera-tures i n order to investigate i t s behavior i n con-nection with the density v a r i a t i o n , as was done i n the case of the pa r a f f i n s . However, s u f f i c i e n t data re-garding densities were not avai l a b l e , and l i m i t s of time prevented the experimental determination of such data. Perhaps the most i n t e r e s t i n g r e s u l t of the inv e s t i g a t i o n of trans-decalin was i t s rather unusual temperature r o t a t i o n e f f e c t . The graph obtained i s c e r t a i n l y not one upon which any powerful argument may be based. However, i t may be sai d that there i s a strong i n d i c a t i o n of a s h i f t of the dispersion con-stants i n the region of 80°C. Since the predominant terms i n temperature v a r i a t i o n of the Verdet constant are density, and r e f r a c t i v e index, one would expect to f i n d such a d i s c o n t i n u i t y i n the corresponding density curves and r e f r a c t i v e index of trans-decalin. Mizuhara has examined these and found no abnormalities as f a r as about 80°. However, his observations d i d not extend to a high enough temperature to conclude that such e f f e c t s are not present. On the other hand, experiments performed i n measuring several other pro-p a r t i e s , such as surface tension and vapor pressures do indicate the p o s s i b i l i t y of d i s c o n t i n u i t i e s i n the same temperature i n t e r v a l . Certainly there i s much investigation l e f t to be done i n t h i s connection. Since the accuracy of the present work was not high enough to attach any signifigance to points on the temperature graph any closer than were taken, no pre-d i c t i o n can be made regarding the actual path of the curve i n the c r i t i c a l region. This suggestts that longer columns of l i q u i d and higher magnetic f i e l d s must be used. Further, an in v e s t i g a t i o n of the c h a r a c t e r i s t i c dispersion frequency over the c r i t i c a l range might provide more conclusive r e s u l t s . The suggestion has been advanced, that the s h i f t i n physical properties i s due to the presence of some new isomer, d i f f e r e n t from the ois and trans forms, (one of the f i v e possible isomers of d e c a l i n ) . I f t h i s were the case, since the dispersion frequency varies continuously with temperature f o r most hydro-carbons, the formation of a new isomer at about 80°C, would attach a new energy to the dispersion electrons, at t h i s temperature. Such an ef f e c t might e a s i l y be observed. Then the actual graph obtained then seems to indicate the p o s s i b i l i t y of an abnormal s h i f t i n the dispersion constants of trans decalin i n the region 78° to 83°C, i n d i c a t i n g some change i n the molecular arrangement. This i s merely an i n d i c a t i o n , and only an exhaustive i n v e s t i g a t i o n of the dispersion i n t h i s region with extended accuracy i n measurement could absolutely v e r i f y such a hypothesis. 2. Octadecane and Docosane The molecular rotations and Verdet constants of the two compounds seem to f a l l into place with those of the other members of the series of lower atomic weights. There i s the usual increase i n Verdet constant with molecular weight. The molecular rot a -tions are f a i r l y close to the Perkin value, and the deviation i s a regular one i n most members of the s e r i e s . The dispersion of the compounds has been found within experimental l i m i t s , to follow the equation {(tf.+0)v-Vx3* ( u ) at l e a s t f o r the temperature measured. This would i n -dicate the p o s s i b i l i t y of extending the Kurtz equation to the prediction of the Verdet constant at various wavelengths and pressures f o r members of the p a r a f f i n s e r i e s . Por octadecane and docosane K and V Q have been determined, and absorption l i n e s should be ex-pected i n the v i c i n i t y of 2.925 x l O 1 ^ s e c . " 1 and 2.923 see."*1 f o r octadecane and docosane respectively. The temperature r o t a t i o n curve obtained f o r octadecane i s a f a i r l y regular one.of the form ex-pected i n such compounds. Although no i r r e g u l a r i t i e s i n the two com-pounds have been found, i t i s i n t e r e s t i n g to observe that these two members of the p a r a f f i n series have e a s i l y predictable Verdet constants on basis of f o r -mula (u), and behave i n a manner s i m i l a r to members of the lower numbered p a r a f f i n series already i n -vestigated. n VI. BIBLIOGRAPHY A. The references given i n the preceding text are as follows: (1) Lorentz, H. A., Theory of Electrons, B. G. Teuhner, L e i p z i g . (2 -(3 (4 (5 (6 (7 (8 (9 (10 (11 (12 (13 (14 Phys. Rev., 18, 65, (1904). Larmor, Aether and Matter, Cambridge University" Press. Walters and Evans, P h i l . Mag. 22, 816, (1936). P h i l . Mag. 13, pp. 905-929 (1933). P h i l Mag. 23, 791-806 (1937.). International C r i t i c a l Tables, Vol. 6, p. 425. Perkin, Trans. Chem. Soc., Vo l . XLV, p. 421 (1884). LI, pp 362-808 (1887). LXIX, p. 1060 (1896). XCI, p. 806 (1907). Rosenfeld, Z. Physik, 57, 8350854, (1929). Seyer and Walker, J n l . Amer. Chem. Soc. , 60, 2125 (1938). Davies, G., M.A.Sc. Thesis, University of B r i t i s h Columbia, 1939. Davenport, C. H., B.A.Sc. Thesis, University of B r i t i s h Columbia, 1939. S. J. Mizuhara, M.A. Thesis, University of B r i t i s h Columbia, 1941. Zotov, G., M.A. Thesis, University of B r i t i s h Columbia, 1941. Smith, H. D., and R. R. Mcleod, J . Amer. Chem. Soc. (on press). Seyer, W. F., and Mann, C. W., J . Amer. Chem. Soo*, 67, 328 (1945). (15) Seyer, W. F., Patterson, R. F. , Keays, J . L., J . Amer. Soc., 16, 179 (1944). (16) Perkin, Trans. Chem. Soc., XLV, 421, 1884. (17) Kurtz, S. S., and L i p k i n , M. R., J. Amer. Chem. Soc. 63, 2158 (1941). (18) L i p k i n , M..R., and Kurtz, S. S., Ind. Eng. Chem.. Analy. Ed., 13, 291, 1941. (19) International C r i t i c a l Tables, Vol. 6, p. 425. B. The following standard reference books have also been used as sources of r e l a t e d information. Brooks, B. L., The Chemistry of the Non-Benzenoid Hydrocarbons. Doss, M. P., Physical Constants of the P r i n c i p l e Hydrocarbons. Drude, P., P r i n c i p l e s of Optics. Gibbs, Optical Methods of Chemical Analysis. Glazebrook, Dictionary of Applied Physics. Jenkins and White, Fundamentals of Physical Optics, McGraw-Hill Book Company,. New York. Monk, Light P r i n c i p l e s and Experiments, McGraw-Hill Book Company, New York, pp. 314, 419, 426, 430. Nernst, W., Theoretical Chemistry. Newton, I., Opticks, Book I I , Part I I I , E d i t i o n of 1717, pp. 245-251. Voigt, Graetz Handbuch, Vo l . 4, p. 393-472, 1920. C. The sources l i s t e d below have provided further useful information. Snow, C , Phys. Rev., 2, 29-38, 1913. Thompson, J . J". , Encyc. B r i t t . 17, 388-391 (1910). (Discussion of Magneto-optics with Bibliography.) 

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