1104 EXPERIMENT STATION RECORD. 



A note on the constitution of phytin, E. Winterstein (Ztschr. Physiol. 

 Chevi., 58 (190S), No. 2, pp. 11 8-1 21). —Data, on the characteristics of nhytin 

 aro snmniarizod and the question of its constitution is discussed. 



The inversion of cane sugar by invertase, II, O. S. Hudson (Jour. Amrr. 

 Chcm. Soc, .W {1908), No. 10, pp. 15(l'i-ir,S3, fifjs. J).— The author points out 

 that the neglect of the nuitarotation of the invert sugar in studying the inver- 

 sion of cane sugar by invertase has led to a series of erroneous conclusions on 

 the laws of the action of this enzym. The investigations which he reports are 

 a critical contribution to tlie subject in continuation of work previously noted 

 (E. S. R., 20. p. 611). 



Gravimetric determination of nitric acid, A. Hes (Ztschr. Analyt. Chem., 

 J,8 (1909), No. 2, pp. 81-98; ahs. in Analyst, S-i (1909), No. 396, pp. lU, 115; 

 Ztschr. Angew. Chcm., 22 (1909), No. 15, pp. 68.',, 685; Jour. Chem. Soc. \ Lon- 

 don], 96 (1909), No. 557, II. p. 265; Chem. Zentbl., 1909, I, No. 7, p. 579).— A 

 study of the influence of concentration of solution and the presence of various 

 other substances on the accuracy of the determination of nitric acid by means 

 cf nitron according to the Busch method (E. S. R., 16, p. 945) is reported. 



It was found that this method gives entirely reliable results when used with 

 a 0.1 per cent nitrate solution. With very dilute solutions the nitric acid is not 

 precipitated or only partly precipitated by nitron. Dextrin, gelatin, and perhaps 

 other organic compounds interfere with the crystallization of nitron nitrate. 

 The presence of aluminum sulphate, magnesium sulphate, ammonium sulphate, 

 potassium phosphate, magnesium chlorid, tartaric acid, citric acid, saccharose, 

 and glucose do not interfere with the accurate determination of nitric acid. 

 Higher results are obtained in the presence of oxalic acid. The difference, 

 however, does not correspond to the amount of oxalic acid present, but is very 

 irregular. 



Chloric acid is quantitatively precipitated by nitron in the form of nitron 

 chlorate in solutions containing about 0.25 per cent of chloric acid. In solu- 

 tions which contain both chlcr'c and nitric acids the nitron precipitates both 

 of these acids quantitatively. 



Modification of the Kjeldahl method, R. Corradi (Indus. Quim., 1908, p. 

 189; (lbs. in Ann. Chim. Analyt., IJ^ (1900), No. 1, pp. 29, 30).— X method 

 specially adapted to the analysis of food materials is described. The nitrogen 

 is determined in the Kjeldahl distillate by decomposition with sodium hypo- 

 bromite and the measurement of the free nitrogen in a Dupre azotometer. 



The determination of potash as potassium molybdic phosphate, A. 

 ScHLicuT {Chem. Ztg., 32 (1908), Nos. 9.i, pp. 1125, 1126; 91,, pp. 11.38-111,0; 

 ahs. in Analyst, 3 J, (1909), No. 39',, p. 39; Jour. Chcm. Soc. [London], 96 (1909), 

 No. 555, II, p. 9.',). — The method proposed is in brief as follows: Mix 0.1 gm. 

 of potassium sulphate free from ammonium salts with 10 cc. of the author's 

 molybdic reagent and evaporate to dryness. Take up with 10 cc. of hot 5 per 

 cent solution of magnesium sulphate, and when cold collect the precipitate on 

 an asbestos filter, wash first with 10 cc. and then with 5 cc. of 5 per cent mag- 

 nesium sulphate, and then again three times with 5 cc. of 5 per cent ammonium 

 nitrate, finally with alcohol and ether. Dry or ignite and weigh. 



The molybdic reagent is prepared as follows: Dissolve 100 gm. of molybdic 

 acid in water, add 2.50 gm. of crystallized sodium carbonate, evaporate to dry- 

 ness, and heat the residue for 2 hours at 150°. Dissolve 500 cc. in water. 

 Dissolve 6 gm. of magnesium pyrophosphate in boiling nitrohydrochloric acid 

 and evaporate repeatedly with nitric acid to expel the chlorin. Dissolve the 

 residue in a little water and nitric acid (specific gravity 1.36) and dilute to .500 

 cc. with acid of the same strength. To this add gradually and with stirring 



