I04 



Journal of Agricultural Research 



Vol. VI, No. 3 



m::^^. 



Reagents. — For the preparation of an alcohol-stearic-acid solution 

 constituents of high quahty were deemed essential for satisfactory 

 work. The purification of alcohol had been a subject for study for 

 a number of years in connection with the ordinary analysis of oils and 

 fats, and excellent results were finally secured by treatment with silver 

 nitrate and caustic lime and redistillation. A strength of 95.25 per 

 cent proved a satisfactory solvent for fatty acids, and greater strength 



was not considered 

 ^^^ necessary or even ad- 

 visable. 



One lot of stearic 

 acid, a mixture of sev- 

 eral grades, was purified 

 by fractional distilla- 

 tion of the ethyl ester 

 in vacuo and subse- 

 quent repeated crystal- 

 lization of the separated 

 acids from alcohol as 

 previously described 

 (4). Another lot of 

 acid with a molecular 

 weight of 271.13 was 

 purified by 10 or more 

 crystallizations from 

 alcohol to a molecular 

 weight of 284.25, and 

 a second portion to 

 284.71, although the 

 resulting leaflets were 

 less perfect than those 

 obtained by the former 

 process. 



When using separa- 

 tory funnels and filter- 

 ing tubes, alcohol-stearic-acid solutions, saturated at o. i ° C, applied to the 

 insoluble acids of butter at the rate of 150 c. c. to 0.5 gm. of material, 

 seldom yielded an appreciable amount of precipitate on standing, even with 

 the addition of crystals of stearic acid and thorough agitation. Solutions 

 testing about 0.22 and 0.24 gm. of stearic acid to 150 c. c. gave somewhat 

 higher results, although of erratic and untrustworthy character. In the 

 attempt to develop a method with this apparatus, over 140 determina- 

 tions were made on butter acids, stearic acid, mixtures of butter and 

 stearic acids, stearic and oleic acids, and stearic, myristic, and oleic acids. 

 The object was not attained, and most of the data will be omitted, as 



Fig. I. — Exterior of constant-temperature crystallization tank. 



