68 AGRICULTURAL EXPERIMENT STATION. [Jan. 



Method for determining Volatile and Non-volatile Fatty Acids 

 contained in Batter (second). 



The sample is prepared by churning the cream in a suit- 

 able bottle, washing the butter well with cold water, melting 

 at50°C. and filtering from the curd through a hot-water 

 funnel. The fat is then heated in the air bath until free 

 from water. 



The method pursued in the determination of the volatile 

 and non-volatile fatty acids is essentially that described by 

 L. F. Nilson, in " Zeit. f. Anal. Chemie," 28, 2, 17(3. 



Two and eight-tenths cubic centimetres to 2.9 cubic centi- 

 metres (approximately 2.5 grams) are measured into a tared 

 Erlenmeyer flask of 250 cubic centimetres capacity, and the 

 exact weight determined. Saponification is' accomplished 

 by adding 1 gram of potassium hydrate dissolved in 2 cubic 

 centimetres of water, and 5 cubic centimetres of strong (95 

 per cent.) alcohol. The flask is provided with a reflux con- 

 denser, and heated until saponification is complete. The 

 alcohol is then driven off, the last traces being removed by 

 means of the following device : the flask is provided with a 

 double perforated rubber cork, one hole carrying a glass 

 tube reaching nearly to the bottom of the flask and provided 

 above with a short rubber tube carrying a pinch-cock, the 

 other connected by means of a rubber tube with a suction 

 pump. By alternately opening and closing the pinch-cock 

 while the pump is working, the last traces of alcohol can be 

 readily removed from the soap. 



Dissolve the soap thus obtained in 30 cubic centimetres of 

 warm water, decompose with 20 cubic centimetres of a 20 per 

 cent, solution of orthophosphoric acid, distil off the volatile 

 acids through a condenser, filtering the distillate, and titrate 

 with decinormal sodium hydrate, using phenolphthalein as 

 indicator. The volatile acids are expelled from the flask by 

 a current of steam. When the distillate amounts to 500 

 cubic centimetres, the operation is considered to be complete. 

 The volatile acids are calculated as butyric. 



The condenser and connections are rinsed back into the 

 flask with boiling water, and the non-volatile acids washed 

 with hot water, and filtered when cool through the same filter 



