AGRICULTURAL CHEMISTRY — AGROTECHNY. 11 



Citrate-solubility of phosphoric oxid in basic slag, E. V. Flack (Chem. 

 Ncu-H, 102 (.1910), yo. 26o7, pp. 221, 222, <lU. in Analyst, 86 (1911), No. 418, 

 p. 32). — The author shows that, as is well rocogruizefl, there is a wide differ- 

 ence between the proportion of phosphoric acid dissolved fi'om basic slag by 

 I'eterniann's neutral amiuonium citrate solution and the proportion dissolved 

 by 2 per cent citric acid solution. 



" The author points ont that, in analyzing the citric acid solution of the slag, 

 if the phosphoric acid be determined by ' direct ' precipitation with magnesia 

 mixture in presence of ammonium citrate, reliable results can not be obtained 

 unless the silica is first removed by evaporation of the solution to dryness with 

 strong hydrochloric acid. Unless this precaution is observed, the percentage 

 of soluble phosphoric acid indicated is, in his experience, on the average about 

 0.5 i)er cent too high." 



Estimating the phosphoric acid in soils and crops, II. Kaserer and I, K. 

 Greisenegger (Ztschr. Landic. ]'ertiuchsic. Ostcn:, 13 (1910), Xo. 10, pp. 795- 

 802; abs. in Chenu Zenthl., 1910, II, No. 21, p. 1631).— The authors utilized 

 Neumann's method (E. S. R., 12, p. 21; 20, p. Ill), with certain modifications, 

 for estimating the phosphoric acid in plants and soils, as follows: 



From 2 to 3 gm. of the comparatively dry substance is burned with sulj)huric 

 acid. 1 drop of mercury, and 1 gm. of potassium sulphate. When the jti'ocess is 

 comi)leted the mixture is transferred to a 105 cc. flask, filled to the mark with 

 water, allowed to stand over night to let the silicic oxid settle, and then filtered. 

 To 150 cc. of the filtrate 50 cc. of ammonium nitrate (500 gm. ammonium 

 nitrate in a liter of solution) is added, the solution heated to from 80 to 90° C, 

 40 cc. of 10 per cent ammonium molybdate solution (100 gm. of ammonium 

 molybdate in 1 liter) added, and the mixtui'e allowed to cool. The solution is 

 filtered through a Gooch crucible containing an asbestos filter (at least 15 

 minutes and not over 3 hours after precipitation and cooling), washed with 

 water and alcohol, and the precipitate washed back into the beaker glass and 

 dissolved with one-fourth-normal sodium hydrate, using phenolphthalein as the 

 indicator. The solution is then boiled for 15 minutes and the excess of alkali 

 titrated back with acid. One cc. of one-fourth-uormal sodium hydrate solu- 

 tion=0.G34 gm. of P2O5. 



Soils (50-gm. sami)les) are decomposed with 100 cc. of nitric acid (1:1), 

 made up to 500 cc. with water, and 100 cc. of the filtrate treated with sulphuric 

 acid but without potassium sulphate, except that soils poor in calcium require 

 the potassium sulphate. 



Determining phosphoric acid by Neumann's method, J. M. Kkasseb 

 (Ztschr. Untersuch. Nahr. ii. Gcnussmtl., 21 (1911), No. 3, pp. 198-200).-^ 

 According to the author good results can be obtained in estimating the phos- 

 phoric acid in canned soups and similar goods with the Neumann method 

 (E. S. R., 12, p. 21; 20, p. Ill) when the necessary precautions are taken. 

 See also previous notes (E. S. R., 20, p. 610. and above). 



Some methods of analyses for soil investigations, A. Yesterbebg (Ver- 

 handl. lutcrnat. Agrogcol. Konf. [Stockholm], 2 (1910), pp. 125-1J,1, fig. 1). — 

 A method for the titrametric estimation of carbon dioxid, carbonates, etc., in 

 soils, which was previously noted (E. S. R., 23, p. 10) is again described, and 

 ihe author points out the advantages to be derived from its use. In addition, 

 he discusses and describes a simplified Pouget and Chouchak method (E. S. R., 

 20, p. Ill) for the estimation of peat and humus in clay soils, and one for 

 titrating humic acid solutions, and a rapid field method for approximately 

 determining the calcium in the soil which depends upon the interaction of 

 calcium carbonate and ferric chlorid, the residual ferric chlorid being deter- 

 mined with potassium sulphocyanate. The author also points out the neces- 



