CHEMISTRY. 283 



A method for separating the " insoluble " phosphoric acid in 

 mixed fertilizers derived from bone and other organic matter 

 from that derived from rock phosphates, A. P. Bryant [Jour. 

 Amer. Cliem. Soc, 18 {1896), No. 6, x)p. 491-498).— The separation 

 depends upon the difference of specific gravity of the materials, and. 

 is accomplished by means of a solution of mercuric iodid (100 gm.) in 

 potassium iodid (75 gm.) made up so that the solution has a specific 

 gravity of 2.2G. 



All water-soluble matter is extracted from 2 gm. of the fertilizer, and 

 the residue is dried before separation. This latter is conducted in 2 

 tubes 0.3 cm. internal diameter, one of which is 7 cm. long and closed 

 at one end, the other 20 cm. long. These tubes are connected by means 

 of stout rubber tubing, so that the parts may be separated by means 

 of a pinch cock. 



The dried residue is placed in one of these combination tubes with 

 15 to 20 cc. of the above solution, shaken up, and allowed to stand 

 until the separation is complete. Then by closing the cock and remov- 

 ing the lower shorter tube, the lighter and heavier portions of the 

 sample are obtained for separate examination. 



Details of manipulation and illustrations of apparatus are given. — 



H. J. PATTERSON. 



On the various modifications of the Pemberton volumetric 

 method of determining phosphoric acid in commercial fertilizers, 



F. P. Veitch {Jour. Amer. Chem. Soc, 18 {1896), No. 4, pp. 389-397).— 

 The paper gives the results of investigation on (1) the method of filter- 

 ing and washing; (2) the time of standing after adding the molybdate 

 solution; and (3) the use of tartaric acid to prevent the precipitation 

 of molybdic acid. 

 The following are the conclusions : 



(1) The use of molybdate solution to which nitric acid has been added, 

 allowing the solution and precipitate to stand one-half hour at 40 to 50°, 

 gave results comparing favorably with those by the gravimetric method. 



(2) The use of tartaric acid gave good results, but possessed no 

 advantage, and extra time of standing made its use undesirable. 



(3) The official molybdate plus 10 cc. nitric acid per 100 cc, using 

 the funnel and paper without pressure in filtering, and only water for 

 washing, was preferred to the usual method. — h. j. Patterson. 



A modified ammonium molybdate solution, A. L. Winton {Jour. 

 Amer. Chem. Soc, 18 {1896), No. 5, pp. 445-446). — Tbe solution is pre- 

 pared according to the following formula: 



(1) Dissolve 1,000 gm. of molybdic acid in 4,160 cc. of a mixture of 

 1 part of concentrated ammonia water (specific gravity 0.90) and 2 of 

 water. (2) Dissolve 5,300 gm. of ammonia nitrate in a mixture of 6,250 

 cc. of concentrated nitric acid (specific gravity 1.4) and 3,090 cc. of 

 water. Add (1) to (2) slowly with constant stirring. Allow to stand 

 and decant off the clear liquid. 



