AGRICULTURAL CHEMISTRY — AGROTECHNY. 805 



is present the precipitation of anmioniuiii-nuinnosiiini ]tliosphate is suuiewliat 

 inhibited. 



Investigations on the determination of phosphorus in fertilizers and 

 feeding stuffs, C. Dusserbe and P. Ciiavan {Mitt. Lcbcnsm. Uniersuch. u. 

 llyg., Schwciz. (l.smUitnamt.. ^ {1013), No. //, /)/;. 261-267; abs. in Clicm. Ztg., 

 37 {1913). Ko. S7. p. S77).— It is statotl that tlio romborton method (E. S. R.. 0. 

 p. SG5), when slightly modified, yields results which are comparable with the 

 method usually used, and is ra[)id, inexpensive to conduct, and has other great 

 advantages. As a result of determining the phosphorus content of meadow hay 

 from various lots harvested in different years, it is said that of each 100 parts 

 of phosphorus from 4 to 9 parts are present as phosphatids, 55 to 74 parts in 

 inorganic combination and as phytin, and 21 to 40 parts as nucleoproteins. 

 By fertilizing with phosphorus the yield and i)hosphorus content of the plant 

 ere increasetl, especially that inorganically combined and the phytin fraction. 

 For determining phosphorus in organic substances (hay extracts) Neumann's 

 method is recommended, but it yielded higher results than the ashing method. 



The estimation of phosphates in soil extracts, J. A. Pbescott {Jour. Agr. 

 Sci. [England], 6 {1914), ^o. 2, pp. 111-120). — A series of experiments made 

 with the object of determining the best conditions under which the Pemberton 

 procedure may be used. The method fiually adopted, inclusive of reagents, is 

 as follows : Reagents — concentrated ammonium nitrate, 500 gm. of ammonium 

 nitrate, in 1 liter of water; ammonium mo-lybdate solution, 150 gm. ammonium 

 molj-bdate dissolved in 1,000 cc. of water and poured into 1,000 cc. of nitric 

 acid (specific gravity 1.2) ; 2 per cent sodium nitrate. 



"A measured volume of soil extract containing 5 to 10 mg. P:Os is evaporated 

 to dryness on a gently heated sand bath and the residue ignited at a dull red 

 heat for 15 minutes, as in Neubauer's method. The residue is taken up with 

 50 cc. of 10 per cent sulphuric acid and digested for half an hour on a sand 

 bath. The extract is diluted if necessary, filtered, and the residue washed with 

 hot water; filtrate and washings amounted to 110 cc. This procedure is found 

 to extract all the phosphate, when the amount of the original solution is not 

 more than 100 cc. in the case of an HCl extract. For soil extracts containing 

 much silica it is necessary to heat the residue from the evaporation for two 

 hours at 120° to 160°, the silica interfering otherwise with the subsequent 

 manipulations. 



" To the solution prepared as above, 25 cc. of the concentrated ammonium 

 nitrate is added and the mixture brought to 55°. Twenty-five cc. of the am- 

 monium molybdate, previously brought to the same temperature, is then added 

 and the mixture stirred, allowed to cool, and filtered after standing two hours. 

 The supernatant liquid is decanted through a filter paper and the precipitate 

 washe<i by decantation several times with a 2 per cent sodium nitrate solution ; 

 this solution prevents the deflocculation of the precipitate, which usually hap- 

 pens when distilled water is used alone. The washing is continued till the 

 washings are no longer acid. The filter is then washed into the beaker with 

 water and the precipitate dissolved in standard alkali and titrated back. 

 For the precipitation it is found convenient to use a water bath kept at 55°, 

 in which the beakers containing the solution are placed till they have acquired 

 .the temperature of the bath. The factor recommended for tenth-normal alkali 

 is: 1 cc. =0.0003004 gm. P^Os." 



Determination of carbon in soils and soil extracts, J. W. Ames and E. W. 



Gaither {Jour. Indus, and Engin. Chem. 6 {1914), ^o. 7, pp. 561-564, fig. 1). — 



It is pointed out that the methods of estimating total carbon in soils by 



oxidation with a mixture of chromic and sulphuric acids have been tested 



94863°— No. Q—15 2 



