468 C. E. FAWSITT AND C. H. FISCHER. 



of water but was easier to work with than the purer cineol 

 of F.P. 0*9° O. used in the later determinations. 



The use in cryoscopy of a solvent containing slight im- 

 purities is justified if the depressions of the freezing point 

 caused by additions of various solutes are the same as they 

 would have given with the purer solvent. Whether this is 

 so, is a matter for experiment in any particular case. 



We have found that when benzene is used as a solute, 

 exactly the same results were obtained with the ordinary 

 and the dried cineol, and we believe that the influence of 

 this small quantity of moisture is negligible for its use in 

 the determinations given below. 



The usual apparatus with a Beckmann thermometer was 

 used for these determinations, except that the stirrer was 

 fitted with a mercury seal, in order to exclude air with its 

 attendant moisture. Without this, or other suitable con- 

 trivance for preventing moisture from entering, it is 

 impossible to obtain results that can be depended on. 



After the freezing point had been registered in any par- 

 ticular determination, the tube containing the solvent and 

 solute was warmed up to nearly the room temperature (16° 

 - 23° O.) before refreezing to obtain another reading. This 

 method gave better results than heating the semifrozen 

 liquid just sufficiently high to melt all solid. 



In the following tables "K," the cryoscopic constant, is 

 the depression in the freezing point caused by dissolving 

 one gramme-molecule of the solute in 1000 grammes of 

 cineol. 



"K" is calculated from the formula 

 K = ffl x A x F 

 w x 1000 

 Where m = molecular weight of the solute. 



A = depression of the freeziig point in degrees 

 centigrade. 



