138 EXPERIMENT STATION. [Jan. 



sodium hydrate solution (equal parts of soda and water filtered) 

 free from carbonate, to 900 cubic centimeters of pure glycerol. 



Ethyl ether, anhydrous and free from alcohol. 



Method.^ — Into a 800 cubic centimeter Erlenmeyer flask 

 are brought 10 grams of fat together with 40 cubic centimeters 

 of glycerol-soda solution, and heated over a naked flame, rotat- 

 ing continuously, until the saponification is complete, as shown 

 by the mixture becoming perfectly clear. The soap is dissolved 

 in slightly warm water, filtered through a dense fat-free filter 

 paper and washed thoroughly. The filter paper and contents 

 are dried and extracted with ethyl ether in a continuous ex- 

 tractor. The extract is dried for two hours in an air bath at 

 100° C, and considered unsaponifiable matter. The use of 

 a separatory funnel might facilitate matters and would probably 

 yield slightly higher results, as soap is somewhat soluble in 

 ether. 



Limit of error, .05 per cent. 



Sijnopsis of Reaction. — Saponification with glycerol-soda. 



Removal of the soap and other soluble materials with water. 



Solution of unsaponifiable matter with ether. 



8upple7nentary Notes. — Unsaponifiable matter includes hy- 

 drocarbons, mineral oils (petroleum and shale oils), tar oils 

 (neutral coal oils), paraffin, ceresin, rosin oils, the solid fat 

 alcohols of the ethane series (cetyl, octodecyl, ceryl and myricyl) 

 and of the aromatic series (cholesterol, isocholesterol, phytos- 

 terol and sistosterol), and possibly some coloring matter. The 

 natural base of wax, monatomic alcohols of ethane series, unlike 

 glycerol, is insoluble in water. Cholesterol is the characteristic 

 solid alcohol of animal fats and oils and phytosterol of the 

 vegetable. 



1 Not applicable for volatile hydrocarbons. 



