RECENT WORK IN AfxRICULTURAl. SCIENCE. 



CHEMISTRY. 



A simple method for determining phosphoric acid by means 

 of molybdic solution, J. Hanamann {Ztschr. Laralw. VersucJisto. 



Oesterr., o {190U),j>j:>. 5S-G2; ahs. in Ohem. J^ew% 83 {1901), No. MJ^S, 

 p. 12). — The author finds that at 40° C. the precipitation can be com- 

 pleted in 10 minutes, even in the presence of solutions containing a 

 considerable quantity of iron, by using a molybdic solution strong 

 in nitric acid. The precipitate filters easih^ washes rapidh", and does 

 not adhere to the sides of the ])eaker. B}" genth' calcining the j^ellow 

 phosphomol^'bdate of ammonium at a uniform temperature not alcove 

 a certain point, a deep blue colored compound of constant composition 

 is obtained, containing, according to Meinecke, 3.9-W95 P2O5. If after 

 calcination the precipitate has not the characteristic deep blue color it 

 should be moistened with ammonia, dried and again calcined. 



The mol^'bdate reagent is prepared as follows: One hundred grams 

 molybdate of ammonia is dissolved in 150 cc. of ammonia of 0.91 sp. 

 gr.,in the presence of lOO gm. of ammonium nitrate. The solution 

 is poured into a liter of nitric acid, sp. gr. l.:2, boiled, filtered, and 

 kept in a brown bottle in a cool place. 



The determination of potash by means of perchloric acid for 

 commercial purposes, C. Monta^aki {iStaz. ^per. Agr. Ital.. S3 

 {1900), No. 5, ijp. JtS^-J(.62; abs. in Chem. CeiitU., 1901, I, No. 3; p. 

 203; Chem. Ztg., 25 {1901), Nn. 20, Rep)erf.,p. 68).—1:\iq reagent used 

 is prepared as follows: Commercial sodium perchlorate, 100 gm., is 

 shaken with 150 gm. of pure concentrated hj^drochloric acid. The 

 solution is filtered through glass wool and the hydrochloric acid ev.ap- 

 orated. In this way a moderately concentrated solution of perchloric 

 acid, or of perchloric anhydrid, is obtained. A solution of the potash 

 salts freed from ammonium salts, containing about 0.5 gm. of the pot- 

 ash salts, is acidified with hydi'ochloric acid, an acidified solution of 

 barium chlorid added, the solution filtered, and the filtrate evaporated 

 to 15 to 20 cc. To this 1 cc. of the perchloric acid solution is added 

 and again evaporated to a sirupy consistency. After cooling, a))out 

 20 cc. of 95 per cent alcohol containing 2 per cent by volume of per- 

 chloric acid solution is added with stirring. After standing 2 hours 

 luoi 



