412 EXPERIMENT STATION RECORD. 



glands of all animals also contain a monobutyi-in and a salol-cleaving euzym. 

 Starcli digesting enzyuis are present in the resting and active glands of the 

 horse and pig, in the active gland of the sheep, and in tlie resting gland of 

 tlie bovine. In the active gland of the bovine amylase was present to only a 

 very slight extent. Peroxidase (guaiac) was present only in the lactating 

 g]and.s and this enzym is apparently not identical with the paraphenylendiamin 

 oxidase. 



About some peroxidase reactions of milk, T. Jona (Arch. Farnmcol. Sper. e. 

 Sci. Aff., 15 (1913), No. 3, pp. 122-130; ahs. in Chem. Zcntbl., 1913, I, No. 20, 

 pp. 1790-1792). — In this investigation both raw and boiled milk were used and 

 to each various preservatives were added to determine their influence upon the 

 outcome of the peroxidase reaction. The effect of temperature upon the peroxi- 

 dase reaction was also studied. The antisei)tics studied were borax 1 per cent, 

 boric acid 1, salicylic acid 0.2, benzoic 0.2, sodium bicarbonate 1, mercuric 

 chloi'id 0.1, a solution of phenol in alcohol, and ammoniacal copper sulphate 

 solution 0.45 per cent. 



Preservatives when present destroyed the peroxidase reaction much quiclier 

 than when milk was heated without them. A strong inhibition, however, was 

 noted with salicylic acid and mercuric clilorid. The peroxidase reaction on the 

 one hand and the acidity of the milk on the other hand may aid in determining 

 the age of a milk, but tlie conclusions drawn on the basis of the peroxidase 

 reaction alone must be considered as final. The addition of acids to milk has 

 various effects on the outcome of the reaction. Acetic, citric, and tartaric acids 

 destroy the reaction with paraphenylendiamin, while the guaiacol test is not 

 influenced even when large amounts of the acids are present. Oxalic, nitric, 

 hydrochloric, and sulphuric acids affect both reactions markedly. 



Peroxidase was not fixed by ordinary substances which liberate active oxygen, 

 but more tests are necessary to clear up this point. Hematin solution (Gaucher 

 test) was decolorized in 6 minutes by boiled milk, but an addition of 20 per 

 cent of raw milk did not decolorize within 25 minutes and 40 per cent of raw 

 milk produced no decoloration whatever. A raw milk containing 0.2 per cent 

 of neutral formaldehyde (38 per cent solution) or hydrogen sulphid decolorized 

 hematin instantly. The same milk, when boiled and after adding 1 per cent 

 hydrogen peroxid, showed an incomplete decoloration within 20 minutes. 

 Potassium bichromate (1 per cent solution) and mercuric chlorid (0.3 per cent) 

 also hinder the reaction. 



The freezing point and chemical composition of the milk from a model 

 farm in 1911 and 1912, J. Schroder (Rct\ Min. Indus. Vntguan, 2 (1914), No. 

 S, pp. 63-67). — This is a study of the milk from four Holstein cows taken at 

 various seasons of the year. The determinations made were specific gravity, 

 fat, ash, total solids, total solids-not-fat, and freezing point. 



The freezing point depression varied from 0.54 to 0.50, with an average of 

 0.547 per cent. The average density of the milk for the expei-imental period 

 was 1.030S at 15° C, the fat content 3.34 per cent, ash 0.71, and total solids 

 11.81. The freezing point was depressed by the addition of water to the milk. 



Analyses were also made of the mixed (composite) milk from the same dairy. 



The freezing-point of milk, J. B. Henderson and L. A. Meston (Chcm. 

 News, 110 (191 J,), Nos. 2S70, pp. 259-261; 2S71, p. 275; 2872, pp. 2S3, 2S4, fig. 

 1). — It is reported that results from 63 samples of milks obtaine<l during the 

 past fi^e years show that in 54 the added water content indicated by the 

 freezing-point was from 0.2 to 9.9 per cent higher than that calculated on an 

 S.5 iier cent solids-not-fat basis, the average being 4 per cent. In five cases, the 

 calculation of added water by the two methods was practically identical. In 



