1019] 



AGRICULTURAL CIIKMISTRY — ACiROTKCHXY. 



509 



Methods for the quantitative determination of the nonprotein nitrogenous 

 constituents of milk, W. DxilIB and A. S. Mi not {.lour. Mot. Clt<m., .;? (1919), 

 No. 3, pp. 85.i-3<U>). — The methods described Include determinations of total 

 nonprotein nitrogen, area, creatinin and creatin, amino nitrogen, and arte add. 



In the procedure for the total nonprotein nitrogen, the proteins and fal are 

 fust removed by heating tin- Bample with copper Bulphate in a solution made 

 0.005 normal with sulphuric arid. After altering, a small amount of ammonia- 

 free formaldehyde is added to the filtrate to prevent the formation of Insoluble 

 amino copper compounds, ami the lactose is then precipitated with cupric 

 hydroxid prepared with calcium hydroxid Instead of sodium hydroxid, on 

 account of the readiness with which an excess can he removed by precipitation 

 with oxalic acid and potassium oxalate. Slight modifications found necessary 

 with human milk consisted of the omission of the sulphuric acid from the cop- 

 per sulphate solution and the addition of a small amount of a 10 per cent solu- 

 tion of disodlum phosphate. In both cases the nonprotein nitrogen was deter- 

 mined by methods similar to that described by Folin and Denis (E. S. K., 36, 

 li. 316) for the total nitrogen in urine. 



For the determination of creatinin and creatin, the colorimetric picric acid 

 method of Folin was found to lie satisfactory after a preliminary precipitation 

 of the lactose by calcium sulphate and calcium hydroxid. The amino nitrogen 

 was determined by the Van Slyke nitrous acid method, employing the micro 

 apparatus. Copper acetate and acetic acid were found to be the most satisfac- 

 tory protein precipitanls with the subsequent addition of potassium oxalate 

 to remove excess of calcium salts. With human milk, copper acetate and 

 disodlum phosphate were employed. Uric acid was determined by precipitation 

 with alkaline zinc acetate, nickel acetate, as suggested by Curtman and Lelir- 

 man (E. S. R., 40, p. 16), having been found to possess no advantage over zinc 

 acetate. 



The technique of all the determinations is described In detail, and a table 

 is given of the results obtained from three samples of cow's milk and three 

 of human milk. The average results are as follows: 



Nonprotein nitroyenous constituents of milk. 



The microanalysis of malted milk, C. W. Ballard {Jour. Amcr. Vharm. 

 Assoc, 7 (1918), No. 4, PP- 826-898, ftys. 8). — The author describes the micro- 

 scopical characters of skimmed milk, whole milk, and malt powders and of 

 dried malt extract, and the characteristic elements In the standard processed 

 malted milk in which enzymic action has taken place, in the so-called mixed 

 malted milk prepared by mechanically mixing certain quantities of powdered 

 milk with malt or malf preparations, and In the substitute or spurious malted 

 milks. 



It is stated that a microanalytical determination of a malted milk can be 

 completed by an experienced worker in less than one hour, and that from such 



