AGRICULTURAL CHEMISTRY AGROTECHNY. 303 



lodonietric estimation of the phosphorus and magnesium in phosphate 

 precipitates, R. Bkandis (Ztscltr. Analyt. Chcm., IiU (1910), No. S-Jf, pp. 

 152-157). — A method is described, in which the magnesium is precipitated as 

 magnesium ammonium phosphate and the ammonia determined by a method 

 which has practically the same basis as that of Artmann previously noted 

 (11 S. R., 22. p. 70.".). 



Methods for the quantitative estimation of inorg'anic phosphorus in 

 veg-etable and animal substances, E. B. Forbes et al. (Ohio Sta. Bui. 215, 

 pp. .'i5!)-'iS9) . — The authors found it necessary to obtain a method for inorganic 

 phosphorus which did not have the disadvantages possessed by the Hart and 

 Andrews' method (E. S. R., 15, p. 496). It is shown that with the latter con- 

 siderable difficulty is encountered in extracting the total amount of inorganic 

 phosphorus present without bringing about a hydrolysis of the phytin. Phytin 

 itself was also found to hinder the precipitation of the inorganic phosphorus. 



The authors have elaborated methods for estimating the inorganic i^hosphorus 

 in plant and animal tissues, which eliminate the above retarding factors. For 

 plant tissues the method consists essentially of the following: The inorganic 

 phosphorus is extracted with a 0.2 per cent hydrochloric acid solution, then the 

 lihytin and the inorganic phosphorus are precipitated with magnesia mixture 

 while the nucleinic acids remain in solution. The inorganic phosphorus is dis- 

 solved out from the precipitate by the aid of a nitric acid solution in alcohol, 

 and the phytin separated from this by means of filtration. The remaining 

 process for determining the phosphorus is the usual oflicial method with molyb- 

 date. Where enzyms are likely to be present, phenol is employed to check 

 their action. 



For animal tissues the method utilized is as follows: "(1) Extraction with 

 boiling ammonium sulphate solution; (2) filtration, concentration by boiling, 

 and precipitation with magnesia mixture; (3) a gravimetric estimation of phos- 

 phorus by precipitation, first with oflicial molybdate solution, then (4) with 

 magnesia mixture, and finally (5) burning to the pyrophosphate. This method 

 is equally api)licable to muscle, liver, kidney, and brain." 



A new sensitive reaction for nitric acid and nitrates, J. Schmidt and H. 

 LuMPP (Bcr. Drut. Chem. GcseU., -',.3 (1910). No. 5. pp. 79J,-797).—A 0.1 per 

 cent solution of di-(9.10-monoxyphenanthryl)amins in concenti-ated sulphuric 

 acid is the reagent. To make the test a small fragment of the salt to be tested 

 is added to from 2 to 3 cc. of the reagent. If nitrates are present a wine-red 

 coloration will be obtained. 



A method for the determination of amino nitrogen and its applications, 

 D. D. Van Slyke (Proc. »S'oc. Expt. Biol, ami Mcd.,7 (1009), No. 2. pp. JiG-J,S; abs. 

 in Chcm. Abs., If (1910), No. 7, p. 933). — This method is based upon the known 

 reaction of aliphatic amins with nitrous acid, RNH,+HN0:;=R0H + Il20-f N:. 



The method proposed requires but little apparatus, is rapid, and is stated to 

 be as accurate as the Dumas or Kjeldahl method. It is carried out in a 35 cc. 

 bottle, fitted with a three hole No. 4 rubber stopper. Through the stopper pass 

 (1) the stem of a 10 cc. burette; (2) the thick-walled capillary inlet from a 

 cylindrical dropping funnel of 25 cc. capacity, the capillary being of 2 mm. in- 

 ternal diameter and reaching nearly to the bottom of the bottle; and (3) an 

 outlet tube for gas, this being a cai)illary from 25 to .30 cm. high, of 1 mm. in- 

 ternal and from 5 to 6 mm. external diameter, with the lower end flush with 

 the bottom of the stoi)per and the u])per end bent in a semicircle to meet the 

 inlet of a gas burette, and with a stopcock near the middle. 



" The amino solution for analysis is placed in the burette, and a few cubic 

 centimeters of water in the dropping funnel. Into the bottle are poured 27 cc. 

 of a 10 : 3 solution of sodium nitrite followed by 7 cc. of glacial acetic acid. The 



