AGRICULTURAL CHEMISTRY. 7 



" Now for uiakiiifr the soil solution weigh 25 gin. of air-dried soil in a stand- 

 ard flask of one litei*. add about 100 cc. distilled water and standai'd nitric 

 acid according to the above-detailed rules. With soils rich in carbonates, 

 take care of the effervescence ; then fill up to 1,000 cc, close the flask, and put 

 it in a rotary apparatus. After half an hour of slow rotation (one rotation 

 lasting about one-half minute) take out the flask, carefully remove the stopper, 

 and allow the solution to stand at room temperature (12 to 2;^°) for about K! 

 hours. Then put the flask again in the apparatus and rotate one-half of an 

 hour again. Now filter the solution and take 25 cc. for the determination of 

 the end acidity of the solution. 



" This is done by titrating it with the above-mentioned standard potash 

 solution, using methyl orange as indicator. If the end acidity would not fall 

 between the 200 and 1,000 mg. N^Os as wanted, repeat the preparation of the 

 solution according to tlje results of the end acidity. If the end acidity is right, 

 the solution is ready for the determination of the phosphoric acid. 



"3. The (leteDiiination of phosphoric acid in flic solution. — Evaporate 800 cc. 

 of the filtered solution to about 50 cc, using a small amount of a 20 per cent 

 anuuonium nitrate solution, for the precipitation of silicic acid. When the 

 solution is evaporated as far as about 100 cc, filter, add 50 to 100 cc. ammonium 

 molybdate solution, heat gently until the precipitation is complete, filter the 

 solution, wash the precipitate with some nitric acid of 5 per cent, dissolve the 

 molybdate precipitate with ammonia, add hydrochloric acid in excess, and again 

 ammonia in excess, and precipitate with the usual magnesia mixture. Tlie small 

 amount of magnesium pliosphate precipitates sometimes very slowly and 48 

 hours should be allowed for complete precipitation. Dry and burn the filter 

 paper in a platinum crucible, ignite, and weigli the magnesium pyrophosphate 

 as usual. The amount of P.O5 found, multiplied by 5, gives the per cent in the 

 soil." 



A comparison of the results obtained by this method and in fertilizer experi- 

 ments on 94 Hungarian soils shows a very satisfactory, agreement and indicates 

 that the method furnishes a reliable index of the available phosphoric acid in 

 the soil. 



On the determination of potash in potash salts and mixed fertilizers by 

 the modified Finkener method, H. Neubaukr {Ztschi: Aiialyt. Chem., Jf6 

 {1901), Ao. -J, pp. 311-31-',; ahs. in Chem. Zentbl., 1907, II, No. 2, p. 182; Analyst, 

 32 (1907), A'o. 376, p. 273). — A recent report by Kling and Engels on tests of the 

 author's modification of this method (E. S. R., 18, p. 108) is referred to and 

 certain improvements of the method, particularly for the determination of potash 

 in mixed fertilizers, are described. 



The present form of the author's method for the determination of potash in 

 mixed fertilizers is as follows : Boil 10 gm. of the substance in a 500 cc. fiask 

 with about 300 cc. of water, then add a drop of phenolphthaleln and sufficient 

 dilute milk of lime to produce a decided red color. After a few minutes add 

 enough oxalic acid to destroy the red color. Cool, fill the flask to the mark, mix, 

 and filter. Evaporate 25 cc. of the filtrate corresponding to 0.5 gm. of substance 

 to dryness in a platinum dish and heat almost to glowing to remove ammonium 

 salts. Take up the residue in water, add a little hydrochloric acid and digest 

 on the water bath with trituration until any floccules of calcium sulphate or 

 silica which may be present are dissolved. Pass through a small filter into a 

 porcelain dish and evaporate with platinum chlorid for determination of potash 

 in the usual way. the reduced platinum being purified l)y washing with hot 

 10 per cent nitric acid. 



The determination of water in proteids, F. G. Benedict and Charlotte K. 

 Manning (.l//*r/-. Jour. I'ln/siol.. 18 {1907), No. 3, pp. 213-221).— Animal and 



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