ECENT WORK IN AGRICULTURAL SCIENCE. 



CHEMISTRY. 



The determination of phosphoric acid as phospho-molybcic 

 anhydrid, Woy (Ghem. Ztg.,21 (1897), Fo. 44, pp. 441-443).— Continuing 

 the work of Meineke and Hundeshagen, tbe author has succeeded in 

 perfecting a method by which phosphoric acid may be determined by 

 means of molybdic solution without subsequent precipitation with mag- 

 nesia mixture. The reagents necessary are a 3 per cent solution of ammo 

 ninm molybdate (120 gm. of molybdate in 4 liters of water), ammonium 

 nitrate solution (340 gin. in 1 liter of water), nitric acid of 1.153 specific 

 gravity (25 per cent IHSTO :i ), and a wash solution containing 200 gm. of 

 ammonium nitrate and 100 cc. of nitric acid in 4 liters of water. The 

 method of procedure is as follows: To an aliquot of the solution corre- 

 sponding to 0.5 gm. of the substance add 30 cc. ammonium nitrate solu- 

 tion and 10 or 20 cc. of nitric acid, and heat over a lamp until bubbles 

 commence to rise. Run into the middle of the hot solution the necessary 

 quantity of the molybdic solution, also heated to the same temperature, 

 keeping the solution in motion with a circular movement of the beaker. 

 The precipitate forms rapidly, and in from 10 to 15 minutes has subsided 

 sufficiently to filter. Filter through a porcelain Gooch crucible with 

 suction. Wash the precipitate by decantation with 50 cc. of the hot 

 wash solution and then redissolve into the same beaker with 10 cc. of 

 an 8 per cent ammonia solution. Add 20 cc. of ammonium nitrate, 30 

 cc. of water, and 1 cc. of molybdate solution. Heat over a lamp as 

 before, and reprecipitate by adding 20 cc. of hot nitric acid, drop by 

 drop, the solution being kept in motion as before. Allow the precipi- 

 tate to subside, filter the solution through the same crucible, and Avash 

 with the wash solution. Place the Gooch crucible inside a nickel cru- 

 cible and heat gradually until the bottom is of a dull red color. After 

 about 15 minutes of this treatment the yellow precipitate is completely 

 converted into the black anhydrid, 24 M0O3 P 2 5 , containing 3.940 per 



Cent P 2 3 . — J. T. ANDERSON. 



On the determination of lime, alumina, and iron in mineral 

 phosphates, L. Lindet ( Compt. Rend. Acad. Met. Paris, 125 (1897), No. 4, 

 pp. 246,247). — The only new analytical feature proposed is the method 

 suggested for destroying the citric acid in a solution from which phos- 

 phoric acid has been precipitated. This is accomplished according to 



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