712 EXPERIMENT STATION RECORD. [Vol.36 



Khoz. Inst., 10 (1914), pp. 38-50; Izv. Moskov. Selsk. Khoz. Inst. (Ann. Inst. 

 Agron. Moscou), 22 (1916), No. 1, pp. 38-50). — The immediate transformatiou 

 of natural calcium phosphate into the diphosphate by the action of small 

 amounts of mineral acids was studied. 



It is concluded that with the use of dilute aqueous or concentrated solutions 

 of phosphoric acid or of pure or technical sulphuric acid there is a complete 

 transformation into the dicalcium phosphate. The treatment with phosphoric 

 acid yields a product which contains from 38 to 39 per cent of total phosphoric 

 acid, 91 per cent of which is soluble. By the use of sulphuric acid the mixture 

 of dicalcium phosphate and calcium sulphate obtained contains 23 per cent 

 total phosphoric acid, 90 per cent of which is soluble. 



Certain negative results were obtained in which the technical phosphoric acid 

 did not decompose the phosphorite either into di- or monocalcium phosphate. 

 This inactivity is being further studied. 



On the decomposition of calcium phosphate by acetic acid, F. V. Chikikov 

 and N. V. Khardin (Iz Reziil't. Veget. Opytov Lab. Rabot (Rec. Trav. Lab. 

 Agron.), Moskov. Selsk. Khoz. Inst., 10 (1914), PP- 104-114; I^v. Moskov. Selsk. 

 Khoz. Inst. (Ann. Inst. Agron. Moscou), 22 (1916), No. 1, pp. IO4-II4).— The 

 authors studied the aotion of dilute acetic acid (2 per cent) on calcium phos- 

 phate. The transition of the phosphoric acid into the soluble state required 

 180 cc. of acetic acid in the case of CaHPO* and 540 cc. in the case of the 

 Cas(PO«)i for every gram of the salt. 



Calcium carbonate lowers the amount of phosphoric acid soluble because it 

 diminishes the amount of acid available for solution and also because of the 

 Introduction of a common ion. Sodium carbonate also lowers the PaOs content in 

 the solution, the effect of such action being even greater than that of the cal- 

 cium carbonate. Calcium acetate diminishes the amount of PjOs in the solution 

 because of again introducing a common ion. The same effect is produced to a 

 greater degree in the case of CaHPO* than in the case of CasP04 by calcium 

 nitrate. 



Extraction of phosphoric acid from phosphorite, V. P. Kochetkov and 

 N. P. KoBLiKOv (Iz Rezul't. Veget. Opytov Lab. Rabot (Rec. Trav. Lab. Agron.), 

 Moskov, Selsk. Khos. Inst., 10 (1914), pp. 12-15; Izv. Moskov. Selsk. Khoz. 

 Inst. (Ann. Inst. Agron. Moscou), 22 (1916), No. 1, pp. 12-15). — The authors 

 have studied the influence of the quantity of sulphuric acid in regard to its 

 concentration, the manner of moistening the phosphate, the temperature, the 

 time of treatment, and stirring in the extraction of phosphoric acid from the 

 natural rock. The data are submitted in tabular form. 



Extraction of phosphoric acid from natural phosphates. — II, The influence 

 of the construction of the stirring apparatus and its speed, A. V. Kazakov 

 (Iz RezuVt. Veget. Opytov Lab. Rabot (Rec. Trav. Lab. Agron.), Moskov. Selsk. 

 Khoz. Inst., 10 (1914), pp. 1-11, figs. IS; Izv. Moskov. Selsk. Khoz. Inst. (An/n. 

 Inst. Agron. Moscou), 22 (1916), No. 1, pp. 1-11, figs. i5).— Continuing pre- 

 vious work (B. S. R., 34, p. 329), a detailed study of the various types of 

 stirring apparatus in general use and the effect of the rate of speed on the 

 extraction of the acid from mineral phosphates is described. 



The Gatterman type of apparatus yielded the most satisfactory results. The 

 effect of the speed was found to depend on certain variables, such as the abso- 

 lute and relative dimensions of the stirrer, the capacity of the vessel containing 

 the material which was being stirred, the viscosity of the mixtures, etc. It is 

 indicated that the fixing of a definite rate of speed is simply empirical, and may 

 be modified in accordance with the variables. 



The preparation of phosphate precipitate, K. N. Shvetsov (Iz RezuVt. Veget. 

 Opytov Lab. Rabot {Rec. Trav. Lab. Agron.), Moskov. Selsk. Kluiz. Inst., 10 



