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THE ROYAL SOCIETY OF CANADA 



The sulphur dioxide used was the ordinary commercial product sold 

 in small tanks. Special precautions were taken to purify it from all 

 traces of water and SO3. This was done by first bubbling the gas 

 through water and sulphuric acid and then storing it in large bottles 

 over concentrated sulphuric acid. After standing thus for a week, it 

 was drawn off through a phosphorus pentoxide tube and condensed 

 by means of a carbon dioxide ether bath. 



A number of attempts were made to determine the solubility in 

 a way similar to that used by the above mentioned workers, but no 

 concordant results could be obtained. The great difference in the 

 boiling point of the two substances excluded the possibility of deter- 

 mining the freezing points by a Becl;man apparatus. Resource was, 

 therefore, had to the bulb method. 



Bulbs with a volume of about 15 c.c. were blown on the ends of 

 tubes 10 cm. in length. Definite weights of cyclohexane were run 

 into the different bulbs and the dried SO2 condensed in them, and 

 while the temperature of the bulbs was still low, the tops of the bulbs 

 were sealed off. They were then weighed. 



At room temperatures the two liquids were miscible at all con- 

 centrations, but on cooling two layers formed. The temperature at 

 which these two distinct layers just disappeared was recorded and 

 is given in Table 1. 



TABLE I 

 Solubility of the Two Liquids 



If the temperature be lowered still more the cyclohexane begins 

 to separate out in the form of colourless crystals. The super-cooling 

 is always considerable, being in some cases as much as 15°, and in all 

 cases as much as 10°. After a considerable amount of solid had 

 formed the temperature was allowed to rise until a point was reached 

 where the amount of solid phase neither increased nor decreased. 

 The temperature was then slowly raised and the point at which the 

 crystals disappeared was taken as the freezing point. A standardized 



