AGKICULTUKAL CHEMISTRY AGROTECHNY. 9 



manner as the milk cnzym by tlic addition of toxic sulistanros sncli as mercnric 

 ohlorid and Lydrocyanic acid. 



It was not possible to snpplant the formaldehyde by sodinui formate, but the 

 addition of the latter to the regular test with platinum was found to accelerate 

 the reduction of the methylene blue. Carbon dioxid was the principal product 

 formed, and in all probability this is due to the oxidation of the aldehyde by 

 the methylene blue. It was also found that formic acid can be employed 

 instead of formaldehyde, but not under the same conditions. 



A new anethod for detecting proteolytic ferments and their antiferments, 

 M. Mandelbaum (Milnchen. Med. Wclinschr.. 56 il90i)). No. JfS, pp. 2215, 2216; 

 (lbs. in Zentbl. Gesam. Physiol, u. Path. Stofficcchsels, n. set:, 4 (1909), No. 23, 

 pp. 903, 90'i). — Two methods are described, one of which consists in allowing 

 the ferment to act upon milk agar (composed of 1 part of milk and 2 parts of 

 ordinary agar) in Petri dishes. The other consists in employing milk in 

 riilenhuth's tubes. 



A new method for purifying peroxidases, X. T. Deleano (Biochcm. Ztschr., 

 19 [1909). No. 3-5, pp. 266-269). — Tests conducted with raphauus extract and 

 colloidal dialyzed iron showed that the latter produced an almost complete 

 precipitation of the proteins without having any effect on the peroxidase 

 activity. 



Laboratory methods for organic nitrogen availability, C. H. Jones (Ahs. 

 in Science, n. ser.. 31 (1910), No. 191, p. 307). — The alkaline permanganate and 

 pepsin methods for determining organic nitrogen availability, as used at the 

 Vermont Station on officially collected commercial fertilizers for the past 12 

 years, are described, and results of these methods on 51 high and low grade 

 animal and vegetable ammoniates now on the market are tabulated and brietiy 

 commented upon. 



The author concludes that the alkaline permanganate method, while em- 

 pirical, is nevertheless valuable to eliminate quickly from a large number of 

 samples those of questionable availability which may then be tested by the 

 longer pepsin process and qualitatively to show more in detail the nature of 

 the nitrogen source. 



Volumetric estimation of sulphates, A. D. Mitchell and C. Smith (Jour. 

 Clirni. Soc. [London]. 95 i 1909), \<i. 566, pp. 2198-2201). — A method is described 

 in which the sulphate is precipitated with barium chlorid, the excess of barium 

 precipitated as chromate, and the excess of chromate estimated by titration with 

 silver nitrate. Ammonium bichromate is used as the indicator, neutral ehro 

 mates being unstable in solution. 



[The quantitative separation of calcium and magnesium in the presence 

 of phosphates and iron], F. H. McCkudden (Jour. Biol. Cliem., 7 (1910), Nos. 

 2, PI). S3-100; 3, p. 201). — This method is particularly applicable to foods, 

 urine, and feces, and where the method of Fresenius and others is inaccurate. 

 It is as follows : 



To the calcium, magnesium, phosphate, and iron solution add 2 drops of 

 dilute alizarin solution and then ammonium hydroxid drop by drop, until an 

 alkaline reaction is just obtained. Then add dilute hydrochloric acid drop by 

 drop to the point of acidity, or if the solution has been warmed by the neutral- 

 izing process add a few drops of acid to excess acidity and then cool the solu- 

 tion and neutralize again. After this add 10 cc. of twice-normal hydrochloric 

 acid and 10 cc. of a 2.5 per cent oxalic acid solution, bring the mixture to the 

 boiling point, and keep the liquid boiling mitil the calcium oxalate separates in 

 a granular form. Then add a 3 per cent ammonium oxalate solution drop by 

 drop to the boiling solution, waiting each time until the precipitate becomes 

 coarsely crystalline. 



