312 EXPERIMENT STATION RECORD. 



constituents arc determined is also jtreseiit in cream. In this work where 

 the total solids, fat, total nitrogen, casein nitrogen, solnble nitrogen, and nitro- 

 gen precipitated by tannic acid were detormiued it was noted that the r.-itio of 

 fat-free dry substance and nitrogenous bodies to nonfat (plasma) is prac- 

 tically the same in cream and milk. 



Investigations in regard to milk serum, A. Burr, F. M. Berberich, and 

 F. Lauterwald {Arh. Vers. Stat. Mollcw. Kiel, 1909, No. 6, pp. 26~7G).—Ot 

 the sera obtained by coagulating milk spontaneously at incubator and room 

 temi)eratures and with rennet or acetic acid, the acetic-acid serum had the 

 highest specific gravity, while the lowest value was obtained with rennet. 

 Acetic-acid sera also contained the most fat. 



It was also concluded that the specific gravity of the serum from fresh 

 mixed milk never falls below 1.026, and that the refraction of spontaneous 

 sera from pure milk never falls below 8 scale divisions of the Wollny refracto- 

 meter. The spontaneous sera obtained from pasteurized milk were somewhat 

 lower in gravity than those obtained from raw milk, while the specific gravities 

 of sera from buttermilk and cream were found not to be wholly indei)endent 

 of the method of souring the cream and producing the butter. 



In judging strongly decomposed milks, the best criterion, according to the 

 authors, is the ash content of the spontaneous serum. They recommend that 

 in addition to determining the fat according to Wollny, when suspicious 

 samples are at hand to note the refraction of the blue solution. 



In regard to the phosphorus in the ash of milk, Bordas and. Touplain 

 (Compt. Rend. Acad. Sci. [Paris}, 152 (1911), No. 13, pp. 899, 900).— The 

 authors determined the total ash, the ash in the serum (obtained by coagu- 

 lating the milk with trichloracetic acid), and the ash in the resulting coag- 

 ulum (casein-butter). The inorganic phosphoric acid, which they believe to 

 be confined to the serum, was determined in the dry substance by calcination, 

 while the organic pho.sphorus which, according to the authors, is in the co- 

 agulum was determined by oxidizing with nitric acid and potassium perman- 

 ganate according to Marie's method. A liter of milk was found to contain 

 total phosphoric acid (PaOo) 1.663 gm., inorganic phosphorus 1.279 gm., and 

 phosi)horus in the coagulum 0.319 gm. 



In regard to the titration of milk fluids, F. M. Berberich (Arb. Vers. Stat. 

 Molkw. Kiel, 1909, No. 6, pp. 86-102). — The author sought to verify and in- 

 vestigate the conclusions of others in regard to the irregular results obtained 

 when determining the acidity of milk, etc., in diluted solutions by titration. 

 He found that by adding potassium oxalate to fresh milk a depression in the 

 acidity content took place, and in order to determine which body in the milk 

 was responsible for the depression he tested solutions of phosphoric acid, 

 citric acid, and lactic acid, in combination with calcium salts, magnesium, 

 and potassium, and in the same proportions as they might exist in milk. 



No connection between these bodies and the depression could be noted, nor 

 could any relation between the protein substances be determined. According 

 to the author, all irregularities caused by dilution, etc., can be overcome by 

 the addition of 5 cc. of a 30 per cent solution of neutral potassium oxalate 

 to 50 gm. of milk. With it the end reaction with phenolphthalein is also more 

 distinct. 



Determination of fat in cream with Wollny' s refractometer, A. Burr and 

 F. M. Berberich (Arb. Vers. Stat. Molkw. Kiel, 1909, No. 6, pp. S^, 85).— 

 Wollny's refractometer when utilized for cream diluted with water does not 

 yield accurate results. When the cream is diluted with skim milk, however, 

 the refractometer gives figures which correspond more closely to those obtained 

 by the Rose-Gottlieb method. 



