RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY. 



Introduction to the investigation of products important in agriculture, 

 C. Bohmer (Anleitung zur Untersuehimg landwirischafdich wichtiger Stoffe. Berlin: Paul 

 Pdrey, 1906, pp. YIII—135). — This book is intended as a guide for students and 

 teachers in agricultural-chemical laboratories. 



The methods described are in the main those approved by the International Con- 

 gress of Applied Chemistry and of the Association of German Agricultural Experi- 

 ment Stations. The topics treated are mechanical analysis of soils; examination of 

 commercial fertilizers, including methods of determining phosphoric acid, nitrogen, 

 potash, and lime; examination of feeding stuffs; determination of the sugar content 

 of beets; milk examination; chemical analysis of soils, including preparation of 

 hydrochloric-acid solutions and their examination, fusion with alkaline carbonates 

 and reduction by means of hydrofluoric-acid, and the determination of nitrogen; and 

 preparation of solutions used in analysis. 



Equilibrium between some bases when they are present simultaneously 

 with phosphoric acid, A. Quartaroli (Gaz. Chim. ItaL, 35 (1905), II, pp. 290- 

 304; Staz. Sper. Agr. ItaL, 38 (1905), No. 7-8, pp. 639-657; abs. in Jour. Soc. Chem. 

 Indus., 24 (1905), No. 23, p. 1229). — The author reports studies of the conditions of 

 equilibrium in the following systems: (1) 1H 3 P0 4 + iCaO (or BaO) -f 2KOH (or 

 NaOH); (2) 1H 3 P0 4 + ^CaO (or BaO) + INaOH ; (3) 1H 3 P0 4 + £MgO + 2NaOH 

 (orKOH); (4) 1H 3 P0 4 + pigO -f lXaOH (or KOH). 



In the experiments which are reported 25 cc. of a normal solution of phosphoric 

 acid was mixed with corresponding amounts of the alkaline solutions and the whole 

 made up to 500 cc. An aliquot of the solution was filtered immediately and the 

 filtrate titrated with twice-normal hydrochloric acid in presence of methyl orange 

 and phenolphthalein. After standing for 2 days another portion of the solution was 

 filtered and titrated in the same way. 



" In system (1) barely one-third of the phosphoric acid present is precipitated, in 

 the form of tri- and tetrabasic salts, and not two-thirds in the form of a double salt 

 Ca 3 (Ba 3 )Na 6 (P0 4 ) 4 , as Berthelot stated. Two-thirds of the phosphoric acid 

 remains in solution in the form of tri- and di-basic salts. The bases are distributed 

 irregularly between the precipitate and the solution. If the system 1H 3 P0 4 + 2 BaO 

 + 2NaOH be allowed to stand for a long time, the precipitate ultimately contains 

 one atomic proportion each of sodium and barium, and nearly one-half of the acid 

 is precipitated. In system (2) also, the bases are distributed irregularly between the 

 precipitate and the solution. The latter contains mono- and dibasic phosphates, 

 whilst the precipitate contains di-, tri-, and, occasionally, tetrabasic salts. Less than 

 two-thirds of the phosphoric acid is precipitated. 



"Magnesia behaves differently from lime and baryta, and its behavior depends 

 also on the kind of alkali present. For example, in system (3) when the alkali 

 employed is sodium hydroxid, the precipitate consists solely of magnesium com- 

 pounds, whilst when potassium hydroxid is used, some alkali is carried down by the 

 precipitate. Jn system (4) much less phosphoric acid is precipitated (only about 



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