AGRICULTUKAL CHEMISTRY — AGROTECHNY. 313 



In regard to the acidity of cream and the buttermilk therefrom, F. M. 

 Berberich and A. Burk {Arb. Vers. Stat. Molkiv. Kiel, 1909, No. 6, pp. 77-S.3).— 

 After discussing the various advantages to be derived from determining the 

 acidity during the process of cream ripening, the authors, as a result of making 

 numerous acidity tests, show that a relation exists between the acidity of the 

 ripened cream and that of the resulting buttermilk, the acidity of the latter 

 being the greater. They further note that the acidity in the buttermilk (butter, 

 serum) obtained from the butter by kneading it is greater than that in the 

 ordinary buttermilk, the cream, and the water-free cream. They believe that 

 either certain bodies are present in butter which have a great affinity for acid or 

 that the butter fat contributes in some way to the acidity figure. The last 

 supposition seemed the more probable. 



A study of the chemical composition of butter fat and its relation to the 

 composition of butter, O. F. Hunzikeb and G. Spitzek {Reprint from Proc. 

 Ind. Acad. Sci., 1909, pp. 15). — The authors agree with Bell that butter fat 

 consists of a mixture of glycerids in which the glycerol is in combination with 

 three different acids, since the glycerol forms tri- and not mono- compounds. If 

 mono-acid compounds were present, the fat would contain tributyrin, which is 

 soluble in 95 per cent ethyl alcohol. In butter, however, only 1.1 per cent is 

 soluble at 20° C, and 3.3 per cent at 75° C. 



The constants found for that portion soluble in cold alcohol (20°) were 

 Reichert-Meissl number 48.1, melting point 16.9°, and soluble acids (as 

 butyric) 9.79 per cent; the portion soluble in hot alcohol (75°) had a Reichert- 

 IMeissl number of 29.6, melting point 39.5°, and soluble acids 6.6 per cent. In 

 contrast to these, for the portion not soluble in either hot or cold alcohol, the 

 constants were Reichert-Meissl number 20.7, melting point 36°, and soluble 

 acids 4.26 per cent. The saponification equivalent of the portion soluble in 

 alcohol was 216.5, which is equivalent to a molecular weight of 649.5, and the 

 portion insoluble in alcohol had a saix)nification equivalent of 260.9 and a 

 molecular weight of 782.7. Tbe molecular weight of butyrln is 302. From 

 these results it is evident that tributyrin is not present in butter fat. 



From an examination of the hard and soft portions of butter fat fractionated 

 according to Richmond's method, it is concluded that the soft portion contains 

 more volatile or soluble acids and more oleic acid in combination with the 

 glycerol than the hard portion. The melting points of the hard and soft portions 

 were 38 and 13.2°, respectively, as compared with that of 32.5° for the original 

 fat. The difference between the melting point of the insoluble fatty acids of 

 the hard and soft parts was not so great as that of the hard and soft portions 

 of the glycerids from which the acids were derived. The soft portion of the 

 glycerids, however, contained a higher percentage of acid, with a lower melting 

 point. " The iodin number of the soft and hard portions of the insoluble acids 

 is higher than that of the corresponding portions of the glycerids of the but- 

 ter fat." 



In regard to the soluble fatty acids, it was found that in both the hard and 

 soft portions they are in combination with practically the same amount of 

 glycerin. "Tue percentage of glycerin combined with the insoluble acids is 

 nearly the same in both soft and hard portions, as the percentage of insoluble 

 acids in the soft and hard portions differs very little. Also the variation in 

 the composition of the insoluble acids would not materially affect the molecular 

 weight. Therefore, it is reasonable to expect that nearly the same percentage 

 of glycerin is combined with the insoluble acids of both the soft and the hard 

 portions." 



The composition of the butter fat was found to vary with the season of 

 the year and the period of lactation of the animal from which the fat was ob- 



