AGRICULTURA.L CHEMISTRY AGEOTECHNY. 807 



The inhibition of the reaction in heated milk is probably due to some altera- 

 tion in its physical condition. Evidently the catalyzer is an organometallic 

 compound which acts chemically but not biolo^cally. 



The original acidity of milk, Bordas ( Orig. Commun. 8. Intemat. Cong. Appl. 

 Chem. [Washington and New York], 18 (1912), Sect. VIIIc, p. 67; abs. in Chem. 

 Ztg., 36 {1912), No. IS-i, p. 1312).— The lack of harmony in the various views 

 concerning the reaction of milk is thought probably due to interpreting the re- 

 sults on the basis of different indicators. The author believes the most appro- 

 priate indicator is phenolphthalein. The total acidity of milk is chiefly due to 

 free casein. Fresh milk never contains a free acid as lactic acid, or citric 

 acid, or any acid salt. When there is an increxise of acidity as a result of the 

 decomposition of lactose, the calcium salt of casein is decomposed before the 

 lactic acidity is manifest. 



A simplification in the method for determining nitrogen, R. Neumann 

 (Chem. Ztg., 36 (1912), No. 66, p. 613).— It is shown in this work that the use 

 of a standardized solution of sulphuric acid in the distillate receiver is unneces- 

 sary, because no measurable losses of ammonia occur. All that is required is a 

 standard acid solution for titrating the collected ammonia and the use of the 

 proper indicator. As aji indicator to be used for all substances exclusive of the 

 salts of ammonia, litmus tinctures, prepared according to Mohr's or Piischel's 

 method, are recommended, but on account of the expense in the preparation of 

 Piischel's, Mohr's tincture is preferred. When the nitrogen is to be estimated in 

 ammonia salts cochineal is to be used, but the nitrogen factor must be corrected 

 accordingly. 



Quantitative separation of potassium from sodium, P. Mabtini (Rend. Soc. 

 Chim. Ital., 2. ser., 4 (1912), No. 6, pp. 113-116).— This is a modification of the 

 Cunningham and Perkin method," and is of particular value when a large ex- 

 cess of sodium is present. The reagent required is composed of crystallized 

 cobalt acetate 90 gm., sodium nitrite 230 gm., and acetic acid (specific gravity 

 1.04) 200 cc, and made up to 1 liter with distilled water. The procedure is as 

 follows : 



To 100 cc. of the solution, containing the potassium and sodium salts in the 

 form of chlorids, 50 cc. of the above reagent and 200 cc. of 96 per cent alcohol 

 are added, stirred, allowed to stand for 24 hours, decanted through a Gooch 

 crucible holding a disk of very thin filter paper, and washed with a little 80 

 per cent alcohol. The precipitate and the ash of the incinerated disk of filter 

 paper are dissolved in hydrochloric acid, the solution is evaporated in a porce- 

 lain dish on a water bath, and a small amount of an aqueous solution of per- 

 chloric acid is added. The potassium is weighed as potassium perchlorate 

 according to Schloesing's method. 



New methods for the determination of sodium and crude fiber, B. B. 

 FoBBES, F. M. Beegle, and J. E. Mensching (Ohio Sta. Bui. 255, pp. 211-216). — 

 The method for sodium is proposed because with the official method it is often 

 difficult to free the combined sodium and potassium sulphates from phosphates. 

 The procedure is as follows : 



"(a) Digest sample with nitric and sulphuric acids in a Kjeldahl flask as 

 for a phosphorus estimation (the sulphuric and nitric acid digestion seems not 

 to introduce a perceptible error through the solution of the Jena glass flask in 

 which this process is conducted) ; make the solution up to volume; take for the 

 determination such aliquots as will represent 2 to 4 gm. each of the fresh sub- 

 stance, and neutralize with ammonia; or (optional) : (b) Moisten the sample 



"Jour. Chem. Soc. [London], 95 (1909), II, pp. 1562-1569. 

 23666°— No. 9—14 2 



