AGRICULTURAL CHEMISTRY — AGROTECHNY. 211 



Determination of phosphorus in phosphates by the volatilization method, 

 r. Jannascu iuid W. JiLKE (Jour. I'rakt. Client., ii. scr., 80 (I'JOU), No. 15, pp. 

 H 3-127, figs. 2). — This was done as follows: The i)hosi)hatc of either iron, 

 chromium, uranium, zinc, nickel, cobalt, or manganese was placed in a silica 

 combustion boat and the whole inserted in the combustion tube, one end of 

 which was packed loosely with glass wool. Carl)on tetrachlorid vapor was then 

 passcil over the phosphate in the tube, which was heated first at a dull and 

 (inally at a red heat. The glass wool served to retain the metal in the tube 

 while the phosphorus passed over into a receiver, possibly as phosphorus oxy- 

 ihlorid, and was estimated as magnesium pyrophosphate. 



Phosphatic feed-lime, <). Kii.i.nkk [Lmuhr. Ir/x. tiini., 70 (191)!)), No.. 5-6. 

 Itp. .'/7/-.}.S0; (lbs. in Jour. (Jieni. Nor. lljmdon]. HIJ ( l!)Oi)), No. 5lil. 11, p. 617).— 

 'Vhe author reconmiends a method for determining idiosphoric acid wliereby 2.5 

 gm. of the finely powdered feed-lime is placed in a dry 4(M» cc. flask with 250 cc. 

 of I'etermann's citrate solution and the whole shaken A hour in the rotary 

 a|)paratus. The solution is then filtered through a dry filter into a dry beaker 

 and .50 cc. of the filtrate treated with 2(t cc strong nitric acid and 50 cc. of water 

 and boiled for 10 minutes. The phosphoric acid is then determined by precipi- 

 tation. 



The quantitative separation of calcium from magnesium, W. C. Blasdale 

 (Jour. Anicr. Clicni. So<:. ,JI ( l!)0!)). No. 8, pp. 917-!>22). — There are three main 

 sources of error in this analysis, namely, the precipitation of magnesium 

 oxalate, the incomplete precipitation of calcium, and errors from occlusion. 

 With a solution containing 0.0 gm. of the sample of calcium and magnesium 

 carbonate, the magnesium not exceeding the calcium, tlie author jjroposes to 

 add 3.5 gm. of anunonium chlorid. dilute with 300 cc. of water, boil, and 

 precipitate with 1 gm. oxalic acid. The solution is tlien neutralized with a 1 

 per cent anunonium-h,vdroxid solution, doing it gradually during a period of 

 5 minutes. When the amount of magnesium is greater than the ciilcium the 

 metliod is modified by making the i)recipitation in 2 stages, just enough pre- 

 cipitant being added during the first to precipitate the calcium. 



Determination of sulphuric acid as barium sulphate, .J. F. Saciier (Clirni. 

 Ztg., 33 (1909), No. 107, pp. 9.',1, 9//2).— After repeating his work (E. S. R., 21, 

 p. 100), the author points out that the losses observed by liup]»in and Folin in 

 this determination are due to the solubility of the precipitate in chlorid of 

 potash, and also to the insufficient excess of the precipitating agent present. 

 The amount of barium sulphate obtained is dependent upon the length of time 

 of heating during and after the precipitation. Precipitation in the cold does 

 not necessitate a large excess of barium chlorid. 



A typographical error in the author's original article, "the amount of hydro- 

 chloric acid must be 1 pei- cent," is corrected to read " some 1 per cent hydro- 

 chloric acid should be added." 



Estimation of potassium in soils as phosphomolybdate, 1'. de Sornay (Bui. 

 Assoc. Chim. Sucr. et DistiU., 26 (1909), No. 10, pp. 978-980; ahs. in Jour. Chem. 

 Sor. [London], 96 (1909), No. 561, II, p. 618).— By adding a definite amount of 

 phosphomolybdic acid to solutions of potassium chlorid, potassium nitrate, and 

 potassium sulphate containing a known amount of potassium, and determining 

 the phosphoric acid in both the filtrate and the precipitate, the author found 

 that potassium phosphomolybdate is not constant in composition. 



A modification of Esbach's albuminoid test, Kwilecki (Miinchen. Med. 

 WchnscJir., 56 (1909), No. 26, p. 1330; abs. in Chcm. Ztg., 33 (1909), No. 102, 

 Rcpcrt., p. 4'tl). — The modification consists in adding ferric chlorid solution to 

 the acidified urine and precipitating the albumin at 72° C. It is claimed 

 that bv this method the albumin can be determined in 2 to G minutes. 



