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The determination of the solubility of solid Trans decahydronaphthalene in liquid sulphur dioxide in… Darling, Peter Atwood 1949

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L is bhj THE DETEBMINATION OF THE SOLUBILITY OF SOLID TRANS DECAHYDRONAPHTHALENE IN LIQUID SULPHUR DIOXIDE IN THE TEMPERATURE RANGE -4-0.06 TO -70.0° A thesis submitted in pa r t i a l fulfilment of the requirements for the degree of Master of Applied Science in Chemical Engineering. P. A. Darling, B. A. Sc. University of B r i t i s h Columbia August 27,19-49. THE DETERMINATION OF THE SOLUBILITY OF SOLID TRANS DECAHYDRONAPHTHALENE f IN LIQUID SULPHUR DIOXIDE IN THE L TEMPERATURE RANGE -40.0° TO -70.0° by P.A.Darling, B.A.Sc. University of B r i t i s h Columbia ABSTRACT The problem is to determine the so lub i l i t y of sol id trans decahydro-naphthalene in l iqu id sulphur dioxide in the temperature range -4-0.0° to -70.0°. Factors affecting the so lub i l i ty determinations are discussed i n de t a i l . Particular emphasis i s placed on the design, construction, and operation of the precision cryostat and the auxi l iary equipment, and on the safety precautions which must be taken. The experimental data i s presented along with a sample calculation to show how the data was treated before the so lub i l i t y graph was plotted. (Since the so lub i l i ty relationship should be approximately l inear i n this temperature range, the "best-f i t t ing" l ine (calculated by the method of least squares) was included in the plot of so lub i l i t y versus temperature. University of B.C. Vancouver, B.C. August 27,194-9 Dr. W.-F. Seyer Dept. of Engineering University of California Los Angeles, Cal. ' , U.S.A. Dear S i r : I hereby submit this thesis in par t i a l fulfilment of the requirements for the degree of Master of Applied Science in Chemical Engineering, Yours t ru ly , ACKNOWLEDGEMENT I am greatly indebted to Dr.W.F.Seyer for his advice on the theoretical aspects of the so lub i l i t y problem and his generous aid in obtaining the materials required for the experiment. TABLE OF CONTENTS Page Introduction 1 Solute and Solvent 2 1. Raw Materials 2 2. Cri ter ion of Purity 3 Factors Which Govern the Process of Solution 4 1. Equilibrium 4'-. 2. Temperature Control 6 3. Discussion 6 Design and Construction of the Precision Cryostat 7 1. Types of Cryostats Considered 7 2. Details of Construction and Method of Operation 8 i . The Nitrogen Reservoir 8 i i . Pressure Control System 9 i i i . Cryostat 9 So lub i l i ty Ce l l 12 Experimental Procedure 13 1. Preliminary Preparations and Experimental Method 13 2. Method of Sampling 14 3. Analysis of the Sample 15 4. Preparation of Standards 15 5. Recorded Measurements 15 Treatment of Data 16 Summary 16 Experimental Data 18 Bibliography 23 TABLE OF ILLUSTRATIONS Opposite Page Photograph of the Apparatus 1 Graph Showing the So lub i l i ty Relationshipsobetween Trans Decahydro-naphthalene and Sulphur Dioxide from -40.0° to -70.0° 18 Following Page F i g . l . S t i r r ing Assembly 24 Fig.2. Heater, Auxi l ia ry S t i r re r , and C e l l Support 24 Fig.3. Miscellaneous Equipment 24 Fig.4« Precision Cryostat 24 PHOTOGRAPH OF THE APPARATUS At the f a r r i g h t , a p o r t i o n of the large vacuum f l a s k holding the l i q u i d n i t r o g e n supply i s seen. S l i g h t l y to the l e f t of t h i s , there i s the winch used f o r r e g u l a t i n g the pressure. Next,the manometer may be seen and to the l e f t of t h i s i n order are the l i q u i d n i t r o g e n r e s e r v o i r , the Dewar f l a s k c o n t a i n i n g the p r e c i s i o n c r y o s t a t , the drying apparatus f o r the n i t r o g e n gas,and the c o n t r o l panel. INTRODUCTION Althuogh a knowledge of s o l u b i l i t i e s . i s of the greatest importance to both the chemist and the chemical engineer, i t i s nevertheless more d i f f i c u l t to predict the so lub i l i t y of a substance in a given solvent than i t i s to predict almost any other property. Planck 1 observed that the relat ion between the change i n free energy and enthalpy i n forming a solution, and hence s o l u b i l i t i e s , could be calculated i f we knew i n addition to the heat of solution, the specific heats of solution and pure substances down to absolute zero, the treatment being analogous to the calculation of chemical equ i l ib r i a by means of the Nernst Heat Theorem. Any method of predicting so lub i l i t i e s which i s to be of much use must be based on the properties of pure substances rather than the properties of the solution, such as specific heat; the determination of which may be more d i f f i c u l t than that of so lub i l i t y i t s e l f . 2 Washburn and Read have shown that i t i s possible to calculate the so lub i l i t y of solids in l iquids in the cases where the substances obey Raoult's Law i n the l i qu id stafce. While the significance of this method of calculation i s very great, i t s scope i s l imited by the re la t ive ly small number of mixtures which obey Raoult's Law throughout the entire range of concentration. I f the deviations from the law, occuring in most solutions, could be accurately predicted, i t would be possible to obtain accurate calculations of so lub i l i t i e s in general. Although i t i s d i f f i c u l t to give an accurate quantitative treatment for these deviations, i t i s possible, however, to make some generalizations of a more qualitative nature with the help of which useful predictions of so lub i l i t y may be made. Even though such predictions are only approximate, they are a very useful guide to accurate so lub i l i t y determinations. 2 The capacity of any system of substances to form a solution has definite l i m i t s . These l imi t s find their most concise expression i n the phase rule of Gibbs: F+P=C+2 where F i s the number of degrees of. freedom in a system of C components with P phases. For two components and two phases (sol id and l i q u i d , two l iqu ids , or two solids) under the pressure of their own vapour and at constant temperature, F equals zero. I f one of the phases consists solely of one component,i.e. a pure substance, the quantitative measure of s o l u b i l i t y i s a single number,viz., the amount of the solute which i s contained in asaturated solution per unit amount of solvent. For any case in which F is zero, a definite reproducible so lub i l i t y equilibrium can be reached. The measure of so lub i l i t y i n this general case i s the set of numbers giving the composition of the phases at a given temperature. Complete representration of so lub i l i ty relations requires determination of the phase diagram, which gives the number, composition, and relat ive amounts of each phase present at any, temperature in a sample containing the components in any specified proportion. SOLUTE AND SOLVENT Raw Materials: Commercial decalin obtained from the Eastman Kodak Co. was fractionated in a lagged Stedman d i s t i l l a t i o n column containing Stedman packing. The s t i l l had a capacity of 3000 cc and was e l ec t r i c a l l y heated. The reflux was controlled by sealing a capi l lary tube to the head of the rectifying column. Water at 20.0°was pumped from a constant temperature bath to the condenser. Reduced pressure of 10.0 mm of mercury was maitained by a vacuum pump. At this pressure i t was found that no pressure regulation device wasrequired to keep the height of mercury in the manometer constant. A sulphuric acid manometer i n connection with the one above showed variations in pressure of less than 1mm. Two fractional d i s t i l l a t i o n s were carried out. From the f i r s t d i s t i l l a t i o n each isomer was obtained about 91% pure. Then each was d i s t i l l e d separately, concentrating the product to about 99% pure as indicated by the refractive index. The f i n a l purif icat ion was obtained by fractional c rys ta l l i za t ion u n t i l a constant freezing point was obtained. To prevent the accumulation of moisture i n storage, the pure isomer after several recrystal l izat ions i s placed in glass-stoppered bottles containing pieces of sodium. Liquid sulphur dioxide was obtained from Baker and Co. i n small iron tanks. Since the vapour pressure of sulphur dioxide i s very high at room temperature, the valve on the tank must be opened carefully to allow only a slow' stream of gas to pass through the pur i f icat ion apparatus. The gas i s bubbled through three wash bottles in series, the f i r s t containing 85% sulphuric acid to remove any sulphur tr ioxide present, the remainder containing concentrated sulphuric acid to remove moisture. The gas f i n a l l y passes through a column containing phosphorus pentoxide to remove any las t traces of moisture or sulphuric acid vapour. The purified gas i s then condensed di rec t ly into the so lub i l i t y c e l l which i s kept i n a freezing mixture of dry ice and acetone. Cri ter ion of Puri ty: The sample of trans decahydronaphthalene was crys ta l l ized five times and had a f i n a l freezing point of -30.6° The sample of cis decahydronaphthalene was crys ta l l ized 16 times and had a f i na l freezing point of -43.340 The sulphur dioxide after one passage through the purif icat ion apparatus was found to have a freezing point of -%.0° According to the l i terature these pure substances should have 3 0 0 the following freezing points: trans decahydronaphthalene -31.48±0.04 cis decahydronaphthalene -43.26 ±0.04 sulphur dioxide^-75.43°±0.05° 4 FACTORS flHICH GOVERN THE PROCESS OF SOLUTION Equilibrium: Since s o l u b i l i t y i s an equilibrium phenomenon, experimental effort i s f i r s t directed to the attainment of saturation. The most satisfactory experimental c r i te r ion to adopt i s the concordance of results obtained when the f i na l state i s reached both from undersaturation and super-saturation. Only when equilibrium has been assured by such a dual approach can the experimenter be certain that the accuracy of his measurements i s correctly given by the precision of i t s component parts: measurements of temperature and concentration, and purity of the materials. I f , however, there i s no information available on the rate of attainment of equilibrium of the system at any temperature i n the required range, then the problem becomes quite tedious, especially when approaching equilibrium at each temperature from the undersaturation side. Since i t i s expedient in such:.a case, the experimenter may dedide to approach equilibrium from the supersaturation sideonly, which leads to results that are readily reproducible although s l igh t ly in error. As a result of their investigations, Noyes and Whitney-5 i n 1897 advanced the theory that a thin layer surrounding the crystals f i r s t becomes saturated and that transfer of material from this layer to the bulk of the solution occurs by a diffusion process.( this theory was confinmed later by King^ with measurements of rate of solution ) . Consequently, rate of attainment of equilibrium i s dependent to a great extent on the viscosi ty of the solution and on the efficiency of s t i r r i n g . More recent work by Hixson and CroweH^ on the dependence of reaction velocity upon surface and agitation l i s t s in de ta i l specific factors affecting rate of dissolution and dis t r ibut ion in a soluble so l id - l i qu id system, which are obviously of prime importance i n the determination of the so lub i l i t y of a solid in a l i q u i d . 5 F i r s t , the rate at which the sol id dissolves in the l i qu id depends upon the diffusion coefficient of the so l id for the given l i q u i d , the specific surface of the part icles of the so l id , the uniformity of dis t r ibut ion in size throughout the particles and the shape characteristics of the par t ic les , which determine the specific surface i n that as they approach those of a sphere the specific surface approaches a minimum. Therefore for fast rates the part icles should be as angular, sharp, and jagged as possible. Second, regardless of whether or not there i s a skin layer of slow moving or stationary l i qu id immediately adjacent to the so l id surface, the agitation of the l i qu id which i s next to this layer or to the surface i s the most importantefactor in the rate of solution of the so l id . The temperature affects the rate of solution in two ways: i t changes the so lub i l i t y , thus increasing the distance necessary to pass through to arrive at equilibrium, and i t increases the actual velocity i t s e l f through i t s kinet ic influence. The temperature coefficient i s considerably less than that of homogeneous reactions. The concentration of dissolved sol id already in solution tends to decrease the rate of solution. The viscos i ty of the l i qu id affects the rate of diffusion and i s frequently the governing factor i n the power-agitation re la t ion . F ina l ly , from the chemical nature of the so l id and l i q u i d i t i s usually possible to predict whether or not they react chemically, the nature of such a feaction and the nature of the products i f they do react. The relat ive density relationships of so l id , l i q u i d , andsolution w i l l determine the best position for the sol id in the so lub i l i t y apparatus to secure the fastest rate of solution. The proportion of sol id and solvent governs the total in te r fac ia l contact surface presented, and other things being equal, the rate varies with the to ta l surface between the phases. 6 Temperature Control: In the determination of so lub i l i t y or any other temperature dependent phenomenon, the degree of control should be on a par with the accuracy of the measurements of the phenomenon under consideration . For this particular so lub i l i t y problem, the temperature should be maintained substantially constant ( i . e . ± 0.05° ) for several hours at a time in the neighbourhood of -40.0°and the control should be such that after equilibrium i s certain at that temperature then the solution may be cooled gradually to -70.0°. The desired degree of control was maintained with a precision cryostat which w i l l be discussed i n more de ta i l la ter . Discussion: There were several factors which narrowed the method of approach to this problem. The s t i r r ing must be eff icient to prevent the occurence of either concentration or temperature gradients within the c e l l . Since the decahydfonaphthalene crystals are less dense than the l i q u i d sulphur dioxide, there must be some device to anchor the crystals at the bottom of the c e l l to prevent interference with the s t i r r i ng equipment and the resistance thermometer which are to be inserted in thesolution. An added advantage in having the l igh t solute at the bottom of the c e l l i s the fact that once dissolved i t w i l l tend to r ise towards the surface of the solution and thus w i l l speed the rate of dissolut ion. Suitable precautions must also be taken to prevent absorption ( by the solution ) of heat and moisture from the surroundings. Much has been written concerning the variat ion of so lub i l i t y with the size of so l id par t ic les , the rea l i ty of the phenomenon, i t s magnitude, and i t s possible effect on the measurement of s o l u b i l i t y . I f sufficient time i s allowed for aging of freshly precipitated sol ids , and for Ostwald ripening ( solution of small particles and growth of large ones ) , the whole effect, however, i s of no major importance to so lub i l i t y measurements. S imi lar ly , while i t i s c ^ 1 1 6 t h a t crystals 7 with l a t t i ce distortions produced by mechanical strain are more soluble • than perfect crystals , the effect i s both of second order and transient. In fact, i n order for either effect to be observed, very sparingly soluble substances must be used to slow down the Ostwald ripening. The decahydronaphthalene i s to be frozen rapidly and tends to become a paraffin-l ike mass. On the surface of this mass there may be many loosely held part icles which are suff ic ient ly fine to cause spurious results by the formation of a co l lo ida l suspension. DESIGN AND CONSTRUCTION OF THE PRECISION CRYOSTAT Types of Cryostats Considered: The precision cryostat described by Walters a nd Loomis0 was developed after a thorough investigation of the merits of several different types of cryostats which are usually divided into general 1 classes: (1) boi l ing l iqu ids , (2) regulationsof flow of heat into a large metal block, the lower end of which i s intermittently dipped into l i qu id a i r , (3) the regulation of flow of heat from the cryostat by means of a pa r t i a l l y evacuated Dewar tube contained in a larger surrounding Dewar tube containing l i q u i d a i r , (4) the automatic cryostat and (5) addition of l i q u i d a i r to the cryostat bath by hand. Each of these types was considered i n de ta i l and due consideration given to their merits with regard to the specific requirements of the so lub i l i t y problem. The boil ing l i q u i d type has been developed by Onnes^ to the point where any desired temperature below o'may be obtained to ±0.01° for periods of an hour or more by the proper regulation of pressure on the boil ing l i qu ids . This type of cryostat would at f i r s t seem to be ideal ly suited to so lub i l i t y measurements but on closer examination i t i s evident' that the equipment necessary for 8 purif icat ion of the l iquids would be very elaborate and far too expensive for the short time that i t would be required to complete the s o l u b i l i t y determinations. Cryostats that depend on the regulation of heat balance i n a large metal block, the lower end of which i s intermittently cooled by l i q u i d a i r , are d i f f i c u l t to operate andvit i s essential that the thermometer and the experimental apparatus be placed at ident ical heat gradients. This type of equipment i s obviously not capable of producing the temperature control which i s required here. The regulation of flow of heat from the cryostat by means of a pa r t i a l l y evacuated Dewar tube surrounded by l i qu id a i r in a second Dewar tube, has been perfected by Keyes} 0 reaching a steadiness of ±0.01° for a period of twenty minutes, using hand regulation. By using the 11 automatic regulator as described by Jackson, a steadiness of ±0 .01 can be maintained. The cryostat bath,which must be a highly inflammable material to remain l i q u i d at low temperatures, usually contains pentane . or similar hydrocarbons. Since the l i qu id a i r in the apparatus i s always bo i l ing , i t becomes continually richer in oxygen. Failure of the inside Dewar tube causes the immediate formation of a mixture of hydrocarbons and l i qu id oxygen which i s highly explosive. The unpleasant p o s s i b i l i t y of sudden demolition of the apparatus and severe injury to the operator i s sufficient reason for rejecting this type of cryostat. Details of Construction and Method of Operation: (l) The Nitrogen Reservoir: The cooling agent was f i r s t placed in a thermos jug which acted as the reservoir. A five l i t e r jug was used because no larger thermos jugs were in stock, but such a small container causes unavoidable delays when i t must be r e f i l l e d . Walters and Loomis used a fifteen l i t e r container which was found to hold enough material for a f u l l day's use. The jug was t ight ly corked to prevent gas leaks. The cork was covered with a layer of petrolatum j e l l y and had an iron bar passing over i t , clamping the cork so r i g i d l y that i t could not be loosened by vibrat ion from nearby equipment. Through this cork pass three holes: one for the pyrex tube which i s connected to the pressure control system, one for the copper tube through which the cooling agent i s forced".J oyer into the cooling apparatus i n the cryostat bath, and the third hole, which is used for r e f i l l i n g the reservoir, i s sealed securely when not i n use. In the. modified cryostat l i q u i d nitrogen was used as the cooling agent in preference to l i q u i d a i r to reduce the f i re hazard and eliminate the poss ib i l i t y of explosion (which was discussed earl ier) (2) Pressure Control System: Vapour from the l i qu id nitrogen reservoir escapes through the pyrex tube mentioned above. The end of the tube i s immersed in mercury which ensures enough positive pressure in the reservoir to force the l i qu id nitrogen through the feed l ine to the cryostat; The escaping vapours cause such a violent surging of mercury in the large tube, .that a small side tube was added i n an attempt to get a better approximation for the reading of the head of mercuryover the end of the vapour exit.The mercury i n the small side tube was found to fluctuate very s l i g h t l y . The pressure control system was so designed that the pressure might be varied from 0 to 70 cm. The winch was bu i l t especially for this equipment and with i t the head of mercury may be altered by as l i t t l e as 1 mm. although experience has shown that such a delicate control was not required and that intervals of 5mm. would be quite sufficient . (3) Cryostat: Liquid nitrogen passes from the reservoir through a ^" i . d . copper, tube (insulated with a layer of rubber and two layers of - J " d. asbestos rope ) into the expansion chamber (see Fig.4-) where the l i q u i d boi ls and the vapour i s led off through a cooling c o i l and directed back to the surface of the bath l i q u i d . Walters and Loomis used casing-head gasoline as the bath l i q u i d and found that i t became viscous and opaque upon absorption of moisture and carbon dioxide from the atmosphere. To prevent th is , they directed the cold vapour back to the surface of the bath l i q u i d . Experience has shown, however, that Petroleum Ether exhibits no tendency to become either viscous or opaque when open to the atmosphere at -70.0. The cooling c i r cu i t i s copper throughout and a l l the joints are sealed with s i lve r solder. Before being ins ta l led , the system was examined for possible leaks by applying compressed a i r at 25psi gauge pressure while the system was immersed i n Petroleum Ether, The cooling c o i l was bu i l t to f i t snugly against the inside of copper-jacketed s t i r r ing assembly. The jacket prevents l a te ra l currents of cold l i qu id and forces a l l the l i q u i d in the bath to pass the cooling c o i l i n a few seconds. The bath l i q u i d i s s t i r red vigorously by three propellers mounted on a shaft passing through the center of the s t i r r i ng assembly. The shaft turns freely i n two babbit bearings which were inserted in the brass plates at the top and bottom of the copper jacket. The jacket and the expansion chamber are held in place by snugly f i t t i n g luc i te discs and the whole assembly r i g i d l y supported by four brass rods as shown in F i g . l . 'Although copper tubing is not to be recommended for a l i qu id nitrogen duct because'its efficiency i s far less than the vacuum-jacketted pyrex tube used by Walters and Loomis, i t i s nevertheless much more eas i ly ins ta l led or removed, i s much less fragilet'than pyrex and on the whole i s quite acceptible in the range -40.0 to -70.0. 1 1 Such r i g i d i t y i s necessary to prevent the s t i r r ing assembly from vibrating against the inside of the pyrex Dewar flask since the pyrex becomes very b r i t t l e at low temperatures.rA<ilid of thick transite was held against the top of the Dewar flask. Since there was an appreciable amount of ice formation on this l i d below - 60 . 0 ° , i t would be advisable to have a layer of cork on each side of the transite for better insulat ion. The header, which had a to ta l resistance of 0 . 5 ohm, was made of nichrome wire wound on a pyrex tube for support and connected to the brass leads as shown i n F i g . 2 . The heater was used only during the t r i a l runs which r. showed that i t was very d i f f i c u l t to raise the temperature s l i g h t l y . For this \ reason the experimental method was modified so that theV'-~ temperature of the bath would not have to be raised at any time during t he experiment. I t was thought at f i r s t that an auxi l ia ry s t i r r e r (shown i n F i g . 2 . ) should be added to speed the c i rcula t ion of the bath l i q u i d . Observation of the c i rculat ing l i qu id with and without the auxil iary, s t i r re r has..- shown that i t does not increase the c i rcula t ion appreciably and the movement of this s t i r re r became very sluggish below -30 . 0 .due to ice formation i n and around the bearing. Since the bath l i qu id i s very vo la t i l e and highly inflammable, i t i s imperative that there be suitable equipment for rapid insert ion and removal of the l i qu id at the beginning and end of the experiment respectively. With the bath l i qu id c i r cu i t (shown in Fig.3. ) i t i s possible to f i l l the Dewar flask i n five minutes and empty i t in less than three minutes. The amount of l i qu id l e f t i n the Dewar flask i s approximately 1 0 0 cc which i s quickly dissipated as the apparatus warms up to room temperature and i s not sufficient to constitute a serious f i re hazard. This modified cryostat was found to give a steadiness of ± 0 . 0 2 ° at -J^J+.O for a period of two hours and ± 0 . 0 4 ° at - 5 2 . 5 for two hours. SOLUBILITY CELL The so lub i l i t y c e l l shown in F ig .3 . was 4" long and 1" o .d . ; made from a pyrex tube with the top flared out s l igh t ly to permit easy insertion of the cork. The resistance thermometer was immersed in the solution to the same depth as the sampling tube. S t i r r ing was effected by allowing a steady stream of dry nitrogen gas bubbles to pass through the solution. The gas was dried thoroughly by passage through concentrated sulphuric acid and a column of calcium chloride before passing into the c e l l , hence the atmosphere between the solution and the cork i s a mixture of sulphur dioxide and nitrogen. This gas i s allowed to seep out around the sampling tube which has a l imited amount of clearance to allow this and also to prevent the inclusion of moisture in the c e l l . When each sample i s taken,the sampling tube is removed for about fifteen seconds which i s not enough time for admission of sufficient moisture to contaminate the c e l l solution. The pure isomer of decahydronaphthalene was to be frozen and held below the surface of the solution. The decalin cup (see Fig .3 . ) was designed to hold the crys ta l l ine mass at the bottom of the c e l l and present as large a surface as possible for rapid attainment of equilibrium. The pure l i qu id was poured into the cup which was then lowered into the c e l l prior to using the c e l l ; as a condenser for the purified sulphur dioxide by cooling i t i n a bath of dry ice and acetone. A small cage (see Fig.2. ) was designed to support the c e l l during experiment and f ac i l i t a t e the removal of the c e l l . By rais ing the two l i t t l e brass tabs at the top of the c e l l support i t i s possible to l i f t about 2" of the c e l l clear of the cryostat. The c e l l can then be completely removed for quick disposal of the l i q u i d sulphur dioxide when the experiment i s over. 13 EXPERIMENTAL PROCEDURE Preliminary Preparations and Experimental Method: Since there i s a constant danger of flash f i res with Petroleum Ether and danger of asphyxiation from inhalation of sulphur dioxide vapour, the f i r s t task of the operator i s to check the carbon dioxide f i re extinguisher and have the gas mask assembled ready for immediate use. The cryostat i s f i l l e d with Petroleum Ether and a large cork i s inserted i n the top of the c e l l support. The platinum resistance therm-ometer projects through this cork and into the bath l i q u i d . Approximately 4.5 l i t e r s of l i q u i d nitrogen i s placed in the reservoir and the i n i t i a l s pressure i s set. The s t i r r i ng motor i s turned on and then the cryostat is l e f t untouched for a period of about two hours, during which the temperature i s recorded occasionally. During this two hour period the operator has l i t t l e time to devote to observation of the progress made by the cryostat. F i rs t , the c e l l and the decalin cup are thoroughly washed and after drying a* 110° i n an oven are allowed to cool to room temperature in a desiccator. Second, the decalin cup i s f i l l e d with the pure isomer and i s lowered into the c e l l which i s attached to the pure sulphur dioxide delivery tube (see F ig .3 . ) and i s then lowered into the dry ice and acetone mixture. The rate of flow of sulphur dioxide i s adjusted so that there i s a steady stream of bubbles through the apparatus. Sufficient sulphur dioxide for one experiment was purified i n an hour. During this hour the sample bottles are washed, dried at 110° in an oven and f ina l ly allowed to cool to room temperature in a desiccator. While the sample bottles are in the oven, the burettes are washed thoroughly, dried and f i l l e d with standard solutions. When the temperature of thecryostat bath i s low enough,the c e l l may be placed in the c e l l support. The resistance thermometer i s removed from the bath and dried before being immersed in the c e l l solution. As soon as the c e l l i s put in the c e l l support, the rate of flow of dry-nitrogen gas i s adjusted to secure adequate ci rculat ion of the solutio n . Next, the sample bottles are removed from the desiccator; :.- ' a predeter-mined amount of standard iodine solution i s added"to each and the weight of each bottle i s then recorded. After these preliminary details are taken care of, the operator i s temporarily free to concentrate his efforts on the maintenance of a cdnstant temperature between -40.0°and -50.0°. When the samples indicate that equilibrium has been reached, the temperatufe w i l l be gradually v reduced to -70.0°without any further attempt to hold the temperature constant at any point. Samples w i l l be taken as often as possible through this range. The descent i s made gradually so that the temperature drop while the sample i s taken ( which i s approximately 15 seconds ) i s negl ig ib le . The basis for the procedure that has been outlined i s the assumption that the excess hydrocarbon present when the saturated solution i s cooled w i l l tend to c rys ta l l i ze on the mass of crystals at the bottom of the c e l l so that the degree of supersaturation w i l l be very s l igh t . Method of Sampling: The sample bottles, each containing a known excess of iodine solution,are placed on a rack from which the f i r s t bottle i s removed, • the sample taken, and the bottle replaced in i t s position on the rack. This procedure i s repeated u n t i l each bottle contains a sample. The bottles are then weighed and replaced in the rack from which each w i l l be removed for analysis as soon as i t i s convenient. Prior to receiving the sample, the bottle i s removed from the rack, placed on the sampling shelf (see Fig.4«)> and the glass stopper removed from the top of the bot t le . The top section of the ground glass joint (see the Dry Nitrogen Assembly, Fig.3.) i s raised clear of the lower section and i s held clear by a hook. The operator then places his 15 thumb over the top of the sampling tube (thus retaining a column of solution in the capi l lary ) ; raises i t ; allows the solution to flush back into the c e l l ; then immerses the sampling tube and removes the next portion of l i qu id which i s allowed to f a l l into the sample bot t le . The glass stopper i s quickly replaced to seal the bottle which i s then returned to the rack to be removed later for weighing and analysis. Analysis of the Sample: The sample collected i n a known excess of standard iodine solution. Trans decahydronaphthalene i s not affected by contact with the iodine solution (see page 18). The cis isomer was assumed to behave s imi la r ly . Sulphur dioxide reacts with iodine according to the reactio n: The excess iodine i s back t i t rated with standard sodium thiosulphate solution according to the following reaction: From the back t i t r a t i on results, and the known weight of sample, i t i s possible to calculate the s o l u b i l i t y . Preparation of Standards: A l i t e r of approximately normal iodine solution i s prepared by dissolving resublimed iodine and C P . potassium iodide in d i s t i l l e d water. The solution, after standing in the dark for three days, was standardized against the purified l i qu id sulphur dioxide so that the strength of the solution may be d i rec t ly correlated to the corresponding weight of sulphur dioxide. The sodium thiosulphate solution was made r. approximately normal and was standardized against the iodine solution. Recorded Measurements: The measurements required for the complete coverage of the experiment are: (a) the date (e) gross wt. of sample bottle (b) the time (f) tare wt. of sample bottle (c) pressure . (g) mis. iodine so l 'n in sample bottle (d) temperature (h) mis. sodium thiosulphate so l 'n 16 TREATMENT OF DATA The following measurements for one sample w i l l be used to i l l u s t r a t e the method of calculat ion. Date: June 16,1949 time • 7:00 P.M. pressure (cm of mercury) 10.0 a temperature. -50.0 gross wt. of sample bottle 55.7368 tare wt. of sample bottle ; 55.5070 mis iodine solution in sample bottle 20.0 mis sodium thiosulphate solution 11.1 1 ml iodine solution =0.0287 grams sulphur dioxide (see page 18) 1 ml sodium thiosulphate solution =1.12 mis iodine solution (see page 18) Weight of Sample: gross wt. 55.7368 tare wt. 55.5070 net wt. 0.2298 grams Iodine Consumed: . '•• mis iodine added : 20.0 mis iodine unused (11.1)(1.12) 12.4 mis iodine consumed : 7.6 Sulphur Dioxide in the Sample: wt. of sulphur dioxide=(7.6)(0.0287) =0.2180 grams =34xl0~'4moles molecular wt. of sulphur dioxide 64.06 Trans Decahydronaphthalene in the Sample: wt. sample 0.2298 wt. sulphur dioxide 0.2180 wt. trans decahydronaphthalene =0.0118 grams =0.853x10-4 moles molecular wt. of trans 138.25 The So lub i l i ty : The results are to be expressed in mole% uni ts . Hence the so lub i l i t y at -50.0° i s : 0.853x10"^- . x 100 = 2.6$ (34.OxlO" 4)(0.85 3xl0" 4 ) SUMMARY The method of obtaining samples by i t s very nature introduces an indeterminate error. The iodine solution (into which the sample fa l l s ) © i s at room temperature and since sulphur dioxide boi l s .a t -10.0, very 17 violent boi l ing occurs as soon as the c e l l solution meets the warmer l i q u i d . The glass stopper i s replaced quickly to seal the sample bottle but some sulphur dioxide must be los t from each sample. There may also be a tendency towards supersaturation.below the temperature at which the i n i t i a l equilibrium i s reached. Both these facts should tend to indicate a higher so lub i l i t y than is actually obtainable. Hence the isomers of decahydronaphthalene are almost completely insoluble in l i qu id sulphur dioxide. I t may seem that the volumetric standards were rather strong for so lub i l i ty determinations, but this was a necessary compromise since i t was desirable to be able to complete the back t i t r a t i on in the sample bottles for rapid analysis. Since the so lub i l i t y relationship seems to be almost l inear throughout the range -40.06 to -70.0°, the so lub i l i t y may be safely calculated from the equation: Y 0.0342X+3.4 where Y i s the mole % trans decahydronaphthalene and X i s the temperature in degrees Centigrade. In the examination"of the l i terature from 1907 to June,1949 inclusive, the closest approach 12 to this problem was made by F. de C a r l i , who reported the relat ive • . so lub i l i t i e s of several organic compounds in l iqu id sulphur dioxide. He mentioned only that decalin was prac t ica l ly insoluble and that the solution was colourless. From-the more detailed examination of the system recorded here, the conclusions'are: (1) there i s no compound formation i n the range and (2) the isomers of decahydronaphthalene are very s l igh t ly soluble in l i qu id sulphur dioxide. GRAPH SHOWING THE SOLUBILITY RELATIONSHIPS BETWEEN TRANS DECAHYDRONAPHTHALENE (SOLID) AND SULPHUR DIOXIDE (LIQUID') IN THE TEMPERATURE RANGE -400° ro-700° I OA 00-—fOO -500 600 TEMPERATURE IN DEGREES CENTIGRADE • 7nn STANDARDIZATION OF IODINE AND SODIUM THIOSULPHATE SOLUTIONS June 8,194-9 Iodine Solution:(A) Standardization against Liquid Sulphur Dioxide gross wt. 43.7746 49.3430 48.9644 tare wt. 48.5133 49.0882 48.6912 net wt. 0.2613 0.2548 0.2732 mis iodine solution 15.0 15.0 15.0 mis thiosulphate solution 5.3 5.4 4*9 net mis iodine solution 9.1 8.9 9.5 grams sulphur dioxide per ml iodine solution 0.0287 0.0286 0.0288 Hence 1 ml iodine solution= 0.0287 grams sulphur dioxide Sodium Thiosulphate Solution:(B) mis thiosulphate solution 20.0 20.0 20.0-mis iodine solution 22.4 22.3 22.3 Hence 1 ml thiosulphate solution - 1.12 mis iodine solution June 29,1949 Sodium Thiosulphate Solution:(C) ' mis thiosulphate solution 15.0 15.0 15.0 mis iodine solution 16.1 16.1 16.1 Hence 1 ml thiosulphate solution= 1.07 mis iodine solution INVESTIGATION OF THE EFFECT OF IODINE SOLUTION (A) ON PURE TRANS DECAHYDR0-NAPHTHALENE June 18,1949 gross wt. 43.5046 41.0698 42.6801 tare wt. 43.2622 40.8425 42.4156 wt. of trans O.2424 0.2273 0.2645 mis iodine solution(A} 10.0 10.0 10.0 time of contact(hours) 72.Q 72.0 72.0 mis thiosulphate solution(B) 9.1 9.0 9.0 Hence there is" apparently no reaction between pure trans and iodine. June 11,1949 Solute: Trans Decahydronaphthalene 19 Solvent: Liquid Sulphur Dioxide Time Press. Temp. Sample Gross Tare Net mis mis net mis grams grams trans cm.Hg. °C No. Wt. Wt. Wt. (A) (B) (A) S0 2 C 1 0 H l 8 10:40AM 7.0 20.0 11:00 7.0 -4.6 11:20 7.0 -14.6 11:40 8.5 -24.0 12:00 8.5 -38.8 12:20PM 8.5 -43.0 12:40 7.0 -45.0 1:00 7.0 -46.6 1:20 7.0 -53.5 1:30 6.0 -55.0 1:40 5.5 -56.5 2:00 3.5 -54-7 2:20 3.5 -54.0 2:40 . 4.0 -52.5 3:00 5.0 -52.5 3:20 5.0 -52.5 3:40" 5.3 -52.5 4:00 4-5 -52.5 4:20 5.0 -52.5 4:40 6.0 -52.5 5:00 6.0 -51.5 5:15 6.0 -49.8 1 213.3846 212.9262 0.4584 20.0 3.9 15.6 O.448O 0.0104 2 230.3727 230.0402 0.3325 20.0 7.7 11-4 0.3270 0.0155 Time Remarks 10:20AM STARTUP— Added 8.5 lbs l i q u i d nitrogen to reservoir. 12:20PM Added 5.5 lbs l iqu id nitrogen to reservoir and started to purify the sulphur dioxide. 2:00Pto Placed, c e l l i n the c e l l support. 5:15PM SHUTDOWN— Liquid nitrogen supply exhausted. The sample bottles are too large. Smaller ones w i l l be used i n future.. 20 June 16,1949 Solute: Trans Decahydronaphthalene Solvent: Liquid Sulphur Dioxide Time Press. Temp. Sample Gross Tare Net mis mis net mis grams grams trans cm.Hg. °C No. Wt. Wt. Wt. (A) (B) (A) S0 2 c i o H l 8 10:20AM : 6.0 20.0 11:00 6.0 -8.6 12:00 7.5 -24.0 1:00PM : 9.0 -43.0 2:00 5.5 -45.0 3:00 5.5 -51.5 4:00 5.5 -50.8 5:00 5.5 -45.0 5:20 7.0 -47.0 5:40 8.0 -48.0 6:00 8.0 -50.0 6:20 10.0 -44.0 6:40 10.0 -45.0 7:00 10.0 -50.0 1 55.7368 55.5070 0.2298 20.0 11 .1 7.6 0 .2180 0 .0118 7:20 4.0 -50.3 7:40 5.5 -47.0 .0161 8:00 9.0 -47.0 2 54-4054 54.0623 0.3431 20.0 7 .7" 11.4 0 .3270 0 8:20 9.0 -50.5 3 55.0287 54-8552 0.1735 20.0 12 .7 5.8 0 .1665 0 .0070 8:40 9.0 -53.2 4 53.9673 53.7568 0.2105 20.0 11 .5 7.2 0 .2065 0 .0040 8:45 9.0 -51.9 5 54.9143 54-7373 0.1770 20.0 12 .5 6.0 0.1720 0 .0050 8:55 9.0 -53.4 6 52.9624 52.7984 0.1640 20.0 12 .9 5.6 0 .1610 0 .0030 9:00 9.0 -53.9 9:30 9.0 -48.0 10:30 9.0 -48.0 10:40 9.0 -52.5 11:00 9.0 -57.5 11:20 9.0 -60.5 7 49.5809 49.3594 0.2215 15.0 6 .6 7.6 0 .2180 0 .0035 11:25 9.0 -62.0 8 48.9175 48.6837 0.2338 15.0 6 .2 8.0 0 .2295 0 .0043 11:40 9.0 -63.6 9 48.2614 48.0371 0.2243 15.0 6 .5 7.7 0 .2210 0 .0033 12:00 9.0 -64.3 10 49.3533 49.1617 0.1916 15.0 7 .6 6.5 0 .1870 0 .0046 12:15AM10.0 -65.0 11 47.1564 46.8800 0.2764 15.0 4 .9 9.5 0 .2725 0 .0039 12:25 12.0 -65.6 12:30 13.0 -65.8 12 47.9590 47.6906 0.2684 15.0 5 .3 '9.1 0 .2610 0 .0074 Time Remarks 10:20AM STARTUP— Added 7.5 lbs l i qu id nitrogen to reservoir. 12:00 Started to purify the sulphur dioxide. 1:00PM Added 6.5 lbs l i qu id nitrogen to reservoir. 2:20PM C e l l solution accidentally contaminated by acetone and dry ice mixture. 2:35PM Started to purify a second batch of sulphur dioxide. 4:00PM Added 6.0 lbs l i qu id nitrogen to reservoir. 5:00PM Placed c e l l i n the c e l l support. 6:00PM Added more Petroleum Ether to the bath so that the l i q u i d levels inside and outside the c e l l are approximately the same. 9:30PM Addedthe las t 5.5 lbs of l i q u i d nitrogen. 12:30AM SHUTDOWN— Liquid nitrogen supply exhausted. The small sample bottles used in this run proved to be satisfactory. June 22,1949 Solute: Trans Decahydronaphthalene 21 Solvent: Liquid Sulphur Dioxide Time Press. Temp. Sample Gross Tare Net mis mis net mis grams grams trans cm.Hg. No. Wt. Wt. Wt. (A) (B) (A) SO, C10H18 5:00PM 9.5 ?20.0 6:00 9.5 -10.4 6:30 9.5 -21.0 7:00 9.5 -28.0 7:30 11.5 -43 .0 8:00 10.0 -41.2 8:30 10.0 -40 .0 9:00 10.0 -45.0 10:00 10.0 -42.0 10:30 7.0 -44.0 11:00 6.0 -44.0 1 41-4769 41.3774 0.0995 10.0 6.0 3.3 0.0949 O.OO46 11:30 6.0 -44.0 2 40.6382 40.5497 0.0885 10.0 .6.3 3.0 0.0862 0.0023 3 40.9787 40.8877 0.0910 10.0 6.3 3.0 0.0862 0.0048 4 40.9507 40.8583 0.0924 10.0 6.2 3.1 0.0891 0.0033 12:00 6.0 -44.0 12:30AM 6.0 -44.O 1:30 10.0 -41.0 2:00 10.0 -45.0 2:20 10.0 -50.0 5 41.6516 41-5833 0.0683 10.0 6.9 2.3 0.0661 0.0022 6 43.0904 43.0233 0.0671 10.0 7.0 2.2 0.0632 0.0039 2:50 10.0 -53.0 7 42.8351 42.7491 0.0860 10.0 6.4 2.8 0.0804 0.0056 3:05 10.0 -55.0 8 40.9561 40.8583, 0.0978 10.0 6.0 3.3 0.0949 0.0029 3:20 10.0 -56.5 9 42 .4331 42.3020 t).13H 10.0 5.0 4.4 0.1265 0.0046 3:55 11.5 -60.5 10 40.0234 39.8668 0.1566 10.0 4-2 5.3 0.1518 0.0048 4:15 11.5 -63.0 11 41.7185 41.6514 0.0671 10.0 6.9 2.3 0.0661 0.0010 4:40 11.5 -65.0 j • 4:50 11.5 -66.2 12 41.5145 41.4500 0.0645 10.0 7.0 2.2 0.0632 0.0013 4:55 11.5 -67.0 13 41.9726 4.1.8980 0.0746' 10.0 6 .7 2.5 0.0718 '0.0028 14 A1.1985 41.0963 0.1022 10.0 5.8 3.5 0.1005 0.0017 Time Remarks 5:00PM STARTUP—Added 7.5 lbs l i q u i d nitrogen to reservoir. 6:00PM Started to purify the sulphur dioxide. 7:50PM Added 7.5 lbs l iqu id nitrogen to reservoir. 9:00PM Placed c e l l i n the c e l l support. 9:30PM Added Petroleum Ether to raise level of bath l i qu id to the required, height. 12:30AM Added the las t 7.5 lbs of l i qu id nitrogen. 5:00AM SHUTDOWN— Liquid nitrogen supply exhausted. 22 July 7,1949 Solute: Cis Decahydronaphthalene Solvent: Liquid Sulphur Dioxide Time Press. Temp. Sample Gross Tare Net mis mis net mis grams grams cis cm.Hg. °C No. Wt. Wt. Wt. (A) (C) (A) S0 2 C m H 18 10:05AM 20.0 20.0 11:05 20.0 -15.4 12:00 20.0 -36.0 1:00PM 20.0 -57.0 1:30 20.0 -36.0 3:15 20.0 -45.0 3:40 20.0 -50.3 4:05 9.0 -50.3 4:30 9.5 -50.3 5:00 11.0 -50.3 6:00 12.5 -50.3 6:15 9.0 -46.0 7:00 12.0 -43.0 7:15 12.0 -43.0 8:00 17.0 -48.0 8:30 20.0 -51.6 8:45 12.5 -52.5 9:45 10.0 -49.8 10:15 15.0 -49.8 1 10:25 15.0 -49.8 2 10:35 15.0 -49.8 3 11:15 20.0 -51.5 11:35 22.0 -52.8 12:00 30.0 -54-5 4 c J 6 12:40AM 30.0 -53.8 1:40 30.0 -48.0 2:30 40.0 -46.0 42.8550 42.6931 0.1619 10.0 4-3 5-4 0.1540 0.0079 41.9164 41.7487 0.1677 10.0 4-1 5.6 0.1608 0.0069 42.0341 41.8857 O.I484 10.0 4-7 4.9 0.1408 0.0076 42.6689 42.5077 0.1622 10.0 4.2 5.5 0.1580 0.0042 41.8927 41.7704 0.1223 10.0 5.5 4-1 0.1178 0.0045 42.3932 42.2649 0.1283 10.0 5-3 4.3 0.1234 0.0049 Time Remarks 10:05AM STARTUP— Added 7.5 lbs l iqu id nitrogen to reservoir. 12:00N00N Started to purify the sulphur dioxide. 1:00PM Added 7.5 lbs l i qu id nitrogen to reservoir. 1:30PM Found the c e l l badly cracked and the c e l l solution contaminated. 2:30PM New c e l l has been made from a pyrex tube, allowed to cool, washed thoroughly,dried,placed in the purif icat ion apparatus, and the flow of sulphur dioxide regulated. 3:00PM Sulphur dioxide tank how empty. Insufficient pure material on hand for the experiment. 4:30PM New tank of l i qu id sulphur dioxide instal led now. Flow of sulphur dioxide regulated again. 6:00PM Added 7.5 lbs l iqu id nitrogen to reservoir. 8:00PM Placed c e l l i n c e l l support. 1:00AM Added the las t 1.5 lbs of l i qu id nitrogen to the reservoir. 2:30AM SHUTDOWN— Liquid nitrogen flow stopped. Feed l ine must be plugged. Since l i qu id nitrogen supply i s very low, w i l l not attempt to continue this run. When the apparatus has thawed out, i t w i l l be examined thoroughly and necessary repairs made. 23 TREATMENT OF DATA FOR THE SOLUBILITY GRAPH 1.TRANS Date Sample Net Wt. Grams Grams Moles SO- Moles C 1 0 H n « Moles Mole % Temp. No. S 0 2 C 1 Q H 1 8 xlOO * xlOO x Sample Trans °C 11/6/49 16/6/49 22/6/49 1 ' 2 1 2 3 4 5 6 7 8 Q 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0.4584 O.448O 0.0104 0.3325 0.3270 0*0055 0.2298 0.3431 0.1735 0.2105 0.1770 0.1640 0 0.2215 0 0.2338 0 0.2243 0 0.1916 0 0.2764 0 0.2684 0 ,2180 ,3270 ,1665 ,2065 ,1720 ,1610 ,2180 ,2295 ,2210 .1870 ,2725 .2610 0.0118 0.0161 0.0070 0.0040 0.0050 0.0030 0.0035 0.0043 0.0033 0.0046 0.0039 0.0074 0.0995 0.0885 0.0910 0.0924 0.0683 0.0671 0.0860 0.0978 0.1311 0.1566 0.0671 0.0645 0.0746 0.1022 0.0949 0 0.0862 0 0.0862 0 0.0891 0 0.0661 0 0.0632 0 0.0804 0 0.0949 0 0.1265 0 0.1518 0 0.0661 0 0.0632 0 0.0718 0 0.1005 0 ,0046 ,0023 ,0048 ,0033 ,0022 ,0039 ,0056 ,0029 ,0046 ,0048 ,0010 ,0013 ,0028 ,0017 0.6990 0.5110 0.3400 0.5110 0.2600 0.3220 0.2685 0.2515 0.3400 0.3585 0.3450 0.2920 0.4250 0.4075 0.1482-0.1348 0.1348 0.1392 0.1032 0.0987 0.1255 0.1482 0.1975 0.2370 0.1032 0.0987 0.1122 0.1570 0.0075 0.0040 0.0085 0.0117 0.0051 0.0029 0.0036 0.0022 0.0025 0.0031 0.0024 0.0033 0.0028 0.0054 0.0033 0.0017 0.0035 0.0024 010016 0.0028 0.0041 0.0021 0.0033 0.0035 0.0007 0.0009 0.0020 0.0012 j 0.7065 0.5150 0.3485 0.5227 0.2651 0.3249 0.2721 0.2537 0.3425 0.3616 0.3474 0.2953 0.4278 0.4129 0.1515 0.1365 0.1383 0.1416 0.1048 0.1015 0.1296 0.1503 0.2008 0.2405 0.1039 0.0996 0.1142 0.1582 1.1 0.8 2.6 2.3 2.0 1.0 1.4 0.9 0.9 0.9 0.7 Qs.l 0.7 1.3 2.1 1.4 2.6 1.7 1.4 2.8 3.0 2.6 1.7 1.5 0.7 0.9 1.8 0.8 -52.5 -52.5 -50.0 -47.0 -50.5 -53.2 -51.9 -53-4 -60.5 -62.0 -63,6 -64.3 -65.0 -65.8 -44.0 -44.O -44.0 -44.0 -50.0 -50.0 -53.0 -55.0 -56.5 -60.5 -63.0 -66.2 -67.0 -67.0 2. CIS Date Sample Net Wt. Grams Grams Moles S 0 2 Moles C i n H Moles Mole % Temp. No. S 0 o C , n H n o xlOO x l 0 0 x u 1 8 Sample Trans °C 7/7/49 1 0.1619 0.1540 0.0079 0.2403 0 .0057 0.2460 2.1 -49.8 2 0.1677 0.1608 0.0069 0.2510 0 .0050 0.2560 2.0 -49.8 3 0.1484 0.1408 0.0076 0.2195 0 .0055 0.2250 2.4 -49.8 4 0.1622 0.1580 0.0042 - 0.2465 0 .0031 0.2496 1.4 -54-5 5 0.1223 0.1178 0.0045 0.1840 0 .0033 0.1873 1.8 -54.5 6 0.1283 0.1234 0.0049 0.1928 0 .0036 0.1964 1.8 -54.5 BIBLIOGRAPHY 1. Planck, Treatise on Thermodynamics; Longmans,Green,and Co.;London, New York,and Bombay,1903. 2. Washburn and Read, Proc.Nat.Acad.,JL,191(1915) 3.Seyer and Walker, J*Am.Chem.Soc.,60,2125-8(1938) 4.Seyer-.and Peck, J.Am.Chem.Soc. ,42,14(1930) 5.Noyes and Whitney, Z.physik Chem.,23_, 689 (1897) 6..King, J.Am.Chem.Soc. ,17,828(1935) 7.Hixson and Crowell, Ind.Eng.Chem.,23,923-31(1931) S.Walters and Loomis, J.Am.Chem.Soc.,47,2302(1925) 9.0nnes, Leiden Communications,Nos.83,94>123a. 10. Keyes, Townshend,and Young, J.Math.Phys.,Mass.Inst.Techn.,1,No.4*213 also Taylor and Smith, J.Am.Chem.Soc,,i4,2450(1921) 11. Jackson, J.Sci.Instruments,2,No.5,158(1925) 12. de Carli,Gazz.chim.ital.,-5J7,347-55(1927) I A/OTES //eater: fitahny e/c/n«n/ of nichromi */r* (mutant* 0-5 okrn ) wound on pyrex fubiny as shown and Silver Soldered lo rAc IcacA »-^ ,cA Jre of td.smc/»/- brass. A v K i / . a r y Stirrer-Stirrer fulley t he*r/nj anJ l/ajei jrc irju. is M" diame/nr s/o&l. Baartny is msd» from /"<// a t?CX?fons/ hra*% T r u / 9</</a</ h ho /tt 3 v A i /* * ry stirrer riy,<J/y /-0 /f-SHfjtt / / ' < / • » / / ? C ^ r » c / « C * <*s / . Ce// 5 t/^ ?orf: 7*p rirtj is 6r-J*> 2 <»•</., /• 6* i.J- t 0-3" fht'tk . 7~A& four CoppQr ^I'SCS f)*re Sfirre oet. and b uf prv, 0-Q2" thick . T/}€SQ. five, ^/eces Jwt/s/ 69 c/e**>pe<t dnct tur*o,tf on /Ac /a/ho. At sec ay m mo, try. Top /ivt f/ftyt J**e j*i*t*,<j throvjf ti />-*y»s//c- ^ /*^c> briss p^Sis St/r»r j«/«/«r«^ ii» p hem- bottom thrt-* tf/'tcs y'o/»t^ A? * copper strap 3nc/^ f wo thin rerffca/ i//'*CS 1 /'/» A) W ton ts / po n't*'** . *t/isctt€ c/ /o £c /t^OTTl trith /wo COppe^ * trips ) to ivfport ftl* LVOffht 0 / the f f t . TU two 6rt9$<> f"sl>s sAot*tn rrjQy />e pi///vot up r d to rfft'se the /owe*- section ce// lypport / 5 " /o fac:/;l*lc ramova' of the ce.//. HE A TCR, A UXILIAR Y 5 TIRRER, AND CELL SUPPORT Vat%: A~ 2/, 1949 E/y 2. .Dryiy- Column C o ^ « y Laye r% of f% Of and C /ws^ b/oo f F>3.4. 

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