191C] AGRICULTURAL CHEMISTRY — AGROTECHNY. ll 



samples. This variation may be accounted for by the production of the catalase 

 by bacteria in the milk while still in the ndder, or later by bacteria from the air. 



The rate of destruction of milk catalase is greatly increased by the rise of 

 temperature. Potassium cyanid and hydrogen cyanid, although decreasing the 

 activity of the enzym, have the effect of causing the enzym to decompose a 

 greater amount of hydrogen peroxid. It is concluded that " there appears to be 

 no doubt that the catalase of milk is analogous to the catalase obtained from 

 blood." 



The persistence of liydrog'en peroxid in milk, E. Hinks (Analyst, 40 (1915), 

 No. 417, pp. 4^2-491)- — The length of time during which varying concentra- 

 tions of hydrogen peroxid persist in both fresh and old milk and the influence 

 of temperature on its persistence was studied. 



It was found that hydrogen peroxid is at first rapidly destroyed but that the 

 rate of destruction gradually diminishes. If the concentration of peroxid is high 

 enough to withstand the rapid initial destruction the residual peroxid remains 

 fairly constant over long periods of time. Fresh milk destroys hydrogen peroxid 

 less readily than 3-day-old milk. The effect of a rise in temperature was to 

 lengthen the time during which peroxid persisted, but the initial destruction was 

 found to be greater at the elevated temperature. It is concluded that the ulti- 

 mate result must be due to the combined destructive effect of the catalase on the 

 peroxid and of the peroxid on the catalase. 



Of the reagents used for the peroxidase reactions paraphenylenediamin was 

 found to be the most generally applicable. On account of the destruction of 

 peroxidase by peroxid it is necessary when testing for the latter to add some 

 fresh milk to the sample in order to insure the presence of peroxidase. In 

 applying the peroxidase reactions for the detection of previous heating the 

 possibility of the milk having received an addition of peroxid must be consid- 

 ered, for a milk containing peroxid and a heated milk will, under certain cir- 

 cumstances, react in exactly the same manner. 



Commercial and industrial analysis (organic), G. Halphen and C. Quii> 

 LAKD (La Practique des Essais Commerciaux et Indiistriels ; Matieres Or- 

 ffaniqites. Paris: J. B. BaiUiere & Sons, 1915, 3. ed., rev. and enl., pp. YII-{-S49, 

 figs. 79). — This volume outlines in detail procedures for the examination and 

 analysis of amylaceous materials, spices, sugar materials and products, liqueiu'S 

 and other fermented beverages, milk, cheese, edible oils, waxes, resins, caout- 

 chouc, mineral oils, fuel, coal-tar products, fats, paper, textiles, tanning mate- 

 rials and leather. The microscopical as well as the chemical analysis is 

 considered. 



Boiling and condensing points of alcohol-water mixtures, P. N. E\ans 

 (Jour. Indus, and Engin. Chem., 8 (1916), No. 3, pp. 260-262, fig. i).— The rela- 

 tion between the boiling point (or condensing point) and the composition of both 

 the liquid and vapor phases of various mixtures of alcohol and water has been 

 determined. These data are presented in tabular form and are of value in deter- 

 mining the quantity of alcohol present in an unknown mixture from its boiling 

 point. The accuracy of the results by this procedure is necessarily less than by 

 the more difficult method of distillation and the determination of the specific 

 gravity of the distillate with a pycnometer. 



The electrolytic determination of iodin present in organic matter, R. B. 

 Krauss (Jour. Biol. Chem., 24 (1916), No. 3, pp. 321-325).— In the proposed 

 method, which is described in detail, palladium is first deposited from an ammo- 

 niacal solution of palladous iodid on a platinum cathode, and the iodin sub- 

 sequently on a silver anode. The new procedure provides an adequate check 

 on a series of determinations by the palladous iodid colorimetric method, pre- 

 viously described by the author (E. S. R., 34, p. 504), but is far less sensitive. 



