RECENT WORK IN AGRICULTURAL SCIENCE. 



CHEMISTRY. 



Improved metliod. for separation and determination of total alkalis in soils, 



J. H. Petit {Jour. Amer. Chem. Soc, 25 {1903), No. 5, pp. 4^6-498). — To avoid error 

 due to presence of barium carbonate the official method is modified as follows: 

 "Just previous to evaporating the solution of the chlorids in platinum dishes a few 

 cubic centimeters of an ammonium sulphate solution — 75 gm. to the liter — are added. 

 The precipitate is filtered and the filtrate evaporated, as usual, in platinum dishes 

 and ignited. In this way the barium is completely removed at one operation and 

 the alfcalis are changed into sulphates, which can l)e ignited over the full heat of the 

 Bunsen burner without danger of loss tlirough volatilization. . . . After igniting 

 to a red heat about 1 gm. of dry, powdered ammonium carbonate is added to the 

 dish and volatilized, thus breaking up any acid sulphates which may have formed." 



The solubility of barium sulphate in ferric chlorid, aluminum chlorid, and 

 magnesium chlorid, G. >S. Fr.\ps {North Carolina Sta. Rpt. 1903, pp. 50-52). — The 

 results o5 tests made by the author at room temperature and compared with results 

 obtained by Fresenius show that barium sulphate is much less soluble in a 10 per 

 cent solution of ferric chlorid or aluminum chlorid than in 10 per cent niti'ic or 

 hydrochloric acid, but more readily soluble in a 10 per cent solution of ammonium 

 chlorid than in a 10 per cent solution of ferric chlorid or aluminum chlorid. In the 

 presence of barium chlorid barium sulphate was found to be less soluble in ferric 

 chlorid or aluminum chlorid than in 10 or 2.5 jier cent solutions of ammonium 

 chlorid, a 2.5 jier cent solution of sodium chlorid, nitric acid, or hydrochloric acid. 



Methods for the determination of total phosphoric acid and potash in soils, 

 C. B . WiLi>iAMs (Jour. Amer. Chem. S(><:, 25 {1903), No. 5, pp. 491-49'J).—f>ee E. S. R., 

 14, p. 630. 



The determination of citric-acid-soluble phosphoric acid, R. Wov (Chem. 

 Ztg., 27 {1903), No. 24, pp. 279, 280). — The author briefly reviews recent literature 

 on this subject, especially that tending to show the superiority of his method (E. S.R., 

 9, p. 321) over that of Bottcher as regards accuracy. Some modifications of the 

 method are described. 



The determination of citric-acid-soluble phosphoric acid in Thomas slag, 

 O. Bottcher {Chem. Ztg., 27 {1903), No. 22, pp. 247, ;?^<S').— Further studies of the 

 applicability and advantages of the author's ]ireliminary test for silica in slags 

 (E. S. R., 14, p. 834) are reported. 



A quick practical method for determining the amount of acid required in 

 the preparation of superphosphates, "\V. Strzoda {Chem. Ztg., 27 {1903), No. 26, 

 p. 299). — To 20 gm. of the lahosphate or fertilizer mixture 30 cc. of crude sulphuric 

 acid about 53° B. is added, the mixture shaken, and allowed to stand 5 hour in a 

 warm place (50 to 80° C.) . The volume is made to 1 liter and free acid determined by 

 titration. Knowing the exact strength of the original acid, the results thus obtained 

 furnish data for calculating the acid required for reducing the phosphate. 



1042 



