218 EXPERIMENT STATION RECORD. 



On the determination of phosphoric acid, F. Raschig {Ztschr. Angew. Chem., 

 18 {1905), No. 24, p. 953).— A reply to Hlavnicka's criticism of the author's method 

 previously noted (E. S. R., 17, p. 6) in which the reliability of the method is main- 

 tained and the use of a clear blue glass is recommended to increase the sharpness of 

 the reaction in titrating with methyl orange. 



Detection of natural phosphates in phosphatic slags, L. Ledoux ( Cong. Chim. 

 Pharm. Liege, 1905, pp. 129-134; abs. in Jour. Soc. Chem. Indus., 24 {1905), Xo. 16, 

 p. 904).— "The method consists in extracting the phosphate, first with citric acid, 

 which dissolves all the phosphoric acid of the slag, and then with nitric acid. The 

 latter extract only gives a precipitate with ammonium molybdate when mineral 

 phosphates have been added to the slag." 



A new reag-ent for potassium, E. P. Alvarez {Chem. News, 91 {1905), p. 146; 

 abs. in Analyst, 30 {1905), No. 352, pp. 254, 255).— The reagent proposed is "icono- 

 gene," sodium amidonaphthol sulphonate, which it is claimed in 5 per cent solution 

 gives in neutral solutions of potash compounds a white, very brilliant, crystalline 

 precipitate of potassium amidonaphthol sulphonate which is slightly soluble in water 

 and insoluble in alcohol. Ammonia salts are not precipitated and magnesia com- 

 pounds do not interfere with the reaction, if sufficient ammonium chlorid is present. 

 Nickel, cobalt, and bismuth give precipitates insoluble in excess of the reagent. 



Contribution to the analysis of nitrate of soda, R. Bensemann {Ztschr. Angew. 

 Chem., 18 {1905), Nos. 24, p. 939; 31, pp. 1225-1228).— -The method proposed (a pre- 

 liminary note on which was referred to in E. S. R., 17, p. 7) is as follows: 



Dissolve 80 gm. of the nitrate in water, making the volume 1,000 cc, dilute 50 cc. 

 of this solution with water, acidify with nitric acid, and add silver nitrate. The sil- 

 ver chlorid precipitated multiplied by 10.192 gives the per cent of sodium chlorid. 

 Dilute a second portion of 50 cc, acidify with hydrochloric acid, and add barium 

 chlorid. The barium sulphate obtained multiplied by 15.236 gives the per cent of 

 sodium sulphate. Evaporate to dryness 100 cc. of the solution with 16 gm. of crys- 

 talized oxalic acid, take up in water, and evaporate to dryness again, repeating this 

 operation 5 times. 



Ignite the residue, heating gently at first, and maintaining at a red heat for 15 

 minutes. Dissolve the ignited mass in water, making the volume 250 cc. Dilute 

 125 cc. of this solution with water, acidify with nitric acid, and add silver nitrate. 

 The weight of silver chlorid obtained multiplied by 24.146 gives the per cent of 

 potassium perchlorate. Titrate 100 cc. of the solution with standard sulphuric acid 

 (80 gm. of S0 3 per liter), or nitric acid (108 gm. of N 2 5 per liter), or hydrochloric 

 acid (73 gm. per liter). The acid required, less 0.2735 cc. for each per cent of sodium 

 chlorid and 0.1305 for each per cent of potassium chlorate, multiplied by 3.375 gives 

 the per cent of nitric acid (N 2 5 ). 



The chlorate is determined by the Gilbert method, as follows: Mix 20 gm. of 

 the nitrate with pyrolusite and some sodium carbonate solution; dry the mixture, 

 melt, and ignite; dissolve the ignited mass in a liter of water; acidify 200 cc. of this 

 solution with nitric acid, and add silver nitrate. The silver chlorid obtained mul- 

 tiplied by 21.359 gives the per cent of potassium chlorate. Tests of the method on a 

 number of samples of nitrate are reported. 



The analysis of cyanamid, R. Perotti {Rend. Soc. Chim. Roma, 1904, p- 192; 

 abs. in Ztschr. Angew. Chem., 18 {1905), No. 23, pp. 906, 907). — In the method pro- 

 posed cyanamid is dissolved in water, and an excess of ammoniacal silver nitrate is 

 added, the excess being determined by the ordinary potassium sulphocyanate 

 method. 



The quantitative estimation of nitric acid and nitrates, \V. H. Easton {Chem. 

 Engin., 1, pp. 142-145; abs. in Jour. Amer. Chem. Soc, 27 {1905) , No. 7, Rev., p. 394). — 

 An electrolytic method of reducing nitric acid or nitrate to ammonia in a copper 

 solution acidified with sulphuric acid and distilling the ammonia into standard acid is 



