RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



The total fatty acids and other ether-soluble constituents of feeding 

 stuffs, J. B. Eatheb {Texas Sta. Bui. 169 (1914), pp. 5-30; ahs. in Jour. Indm. 

 and Engin. Chon., 7 (1915), No. 1, pp. .?//, 35). — In some previous publications 

 (E. S. R., 28, p. 108; 31, p. 71) "it has been shown that the unsaponifiable 

 matter in the ether extract of hays and fodders averages about 5S per cent 

 of the total extract, and is of mucli lower digestibility than the saponifiable 

 matter. It has also been shown that chloroform extracts comparatively large 

 percentages of material from hays and fodders jjreviously extracted with ether, 

 and that this extract contains fatty acids." A method was described by means 

 of which it was possible to separate the constituents of the exti-act into three 

 fractions: Unsaponified (largely wax alcohols), uncolored saponified (fatty 

 acids), and colored saponified (chlorophyll and related compounds), and desig- 

 nated the digestion method. 



An improved method (precipitation method) for the determination of total 

 fatty acids and nonsaponifiable matter of the ether extract has now been 

 devised. " This method for the separation of the constituents of ether extracts 

 into three fractions is essentially as follows: Saponify the ether extract, acidify 

 and dissolve in ethei", precipitate the fatty acids from ethereal solution with 

 aqueous alkali, and remove by washing with water. Acidify the soap with 

 acetic acid and shake with petroleimi ether to dissolve fatty acids and then with 

 ethyl ether to dissolve the residue." 



Another new method is proposed which utilizes an alcoholic soda solution 

 for dissolving the fats. "Alcoholic soda i)robably dissolves less nonfats than 

 aqueous soda ; soap solutions in alcohol are more easily manipulated ; and fats 

 are soluble in alcohol alone. The advantages of alcohol over water thus appear 

 to be considerable. The use of aqueous alkali would not i)revent the contamina- 

 tion of the soap with unsaponified material, because the latter is both soluble 

 in soap solutions and emulsifiable with aqueous alkali. 



" Ether extracts of the concentrates contained saponifiable material which 

 does not appear to be fatty acids, averaging about 8 per cent, and unsaponi- 

 fiable matter averaging about 6 per cent, a total of approximately 14 per cent of 

 nonfats in the ether extract of concentrates. Ether extracts of hays and excre- 

 ments from them contain saponified material which does not appear to be fatty 

 acids, averaging about 15 per cent of the ether extract. Together with the 

 unsaponifiable matter, they made a total of approximately 68 per cent of non- 

 fats in the ether extract of rougliages. Molecular weight determinations and 

 other evidence indicate that the ether soluble, petroleum-ether soluble acids 

 in the alcoholic soda extracts of feeding stuffs are pi'obably fatty acids. 



" The digestibility of the various ether-soluble fractions was determined in 

 six hays with sheep. The fatty acids are digested on an average of 00.5 per 

 cent in the ether extract; the fatty acids in the alcoholic soda extract were 

 digested o.*?.? per cent. The digestibility of the fatty acids extracted by alco- 



709 



