AGRICULTURAL CHEMISTRY — AGROTECHNY. 413 



three other cases the estimated added water on the 8.5 per cent solids-not-fat 

 basis from 1.7 to 3.9 i>or cent lower than by the freezin^'-point. 



The freezing-point of milk as a standard for the detection of watering is 

 discussed and the method of application describetl. 



Determination of the amount of water added to milk based on the degree 

 of acidity, V. Gero (Kiserlet. Kozlem., IG (1913), No. 5, pp. 663, 66ft; o&s. in 

 Intcrnat. Inst. Agr. [RomG'\, Mo. Bui. Agr. Intel, and Plant Diseases, 5 (lOUf), 

 No. 1, pp. 125, 126). — In using the acidity determination as an index for the 

 freshness of a milk it was noted that the acidity of a wateretl milk was far 

 below that of a pure milk. In Hungary the acidity of milks collected in the 

 open market ranged between 17 and 22° (Thorner's method) while milks adul- 

 terated with water showed lower than 15° and in some cases as low as 10°. 



A rapid method for determining the percentage of casein in milk, W. O. 

 Walker {Jour. Indus, and Engin. Chem., 6 (1914), No. 2, pp. 131-133; abs. in 

 N. Y. Produce Rev. and Amer. Cream., 37 (19U), No. 26, pp. 1154, 1155).— A 

 discussion of the principles underlying and the value of the test previously 

 noted (E. S. R., 31, p. 114). The average difference between 63 determinations 

 as compared with the Hart centrifugal method ^E. S. R., 20, p. 12) was 0.03+ 

 I>er cent. 



The estimation and significance of the ammonia content of milk, J. Till- 

 MANs. A. Splittgerber, and H. Riffart (Ztschr. Unterstich. Nahr. u. Oenussmtl., 

 27 {1914), No. 1-3, pp. 59-76). — For the determination of the ammonia content 

 of milk it is advisable first to remove the greatest part of the proteins with 

 either a mercux'ic chlorid-hydrochloric acid solution or with lead subacetate in a 

 sodium phosphate solution. The lead subacetate serum is treated with magne- 

 sium chlorid and sodium phosphate and the ammonia pi'ecipitated as magne- 

 sium ammonia phosphate. The precipitate is placed, filter paper and all, in a 

 flask and distilled with magnesium oxid at atmospheric pressure. The method 

 gives results which are comparable with those obtained by the vacuum method, 

 which is cumbersome. Fresh milk contained from 3 to 4 mg. of ammonia per 

 liter. The ammonia increases with the age of the milk and by boiling the milk 

 at atmospheric pressure. 



Under experimental conditions, cows' feces when added to milk did not 

 increase the ammonia content at once, but did several days later. The deter- 

 mination of the ammonia content of milk is deemed of no value for detecting 

 added water, but is a far better criterion for detecting bacterial contamination 

 than either the methylene blue test, the degree of acidity, or the alcohol test, 

 and is also valuable for judging milk destined for infant feeding. 



The Neusal butyrometric method, E. Reggiani {Mod. Zooiatro, Parte ^cL, 

 No. 1 {1914), pp. 9-21). — A study of the method with normal, sterilized, boiled, 

 watered, and skim milk, and milk preserved with hydrogen peroxid, lime water, 

 salicylic acid, bichromate of potash, formaldehyde, boric acid, and sodium bi- 

 carbonate. As a rule the results obtained were slightly higher than those 

 given with the usual acid butyrometric method, with the exception of the milk 

 preserved with formaldehyde and the milk boiled for ten minutes w^here the 

 results are lower. 



An apparatus and method for determining the hardness of butter fat, A. E. 

 Perkins {Jour. Indus, and Engin. Chem., 6 {1914), ^o. 2, pp. 136-141, figs. 4)-— 

 A description of an apparatus and method which is said to give more accurate 

 results than methods ])reviously described. With the method it is necessary to 

 stir the sample while cooling to prevent the separation of zones of different 

 hardness. Temperature was found to have a very marked effect on the hard- 

 ness of the fat. and it is recommended that in testing for hardness the sample 

 be kept at a constant temperature for six hours or more before heating. 



