CHEMISTRY. 15 



case no color is developed, to a volume of about 5 cc. Then, with two portions of 

 treated soils, one of which has been rendered alkaline by the limewater and the 

 other of which is still acid, as guides, prepare three fresh portions of 10 gm. each 

 and add limewater as before, except that the amount added to a dish differs from 

 that added to another by 1 or 2 cc. Dry, take up with 100 cc. of water, allow to 

 stand, draw off, and treat exactly as before. The smallest amount of limewater 

 which gives the characteristic pink color is taken as the acidity equivalent of the 

 soil. Each cubic centimeter of standard limewater is equivalent to an acidity of 

 0. 01 per cent expressed as calcium oxid. 



"It is essential that the distilled water used be free from alkalis and acid." 



Notes on rapid soil analysis, V. Edwards ( Chem. News, 89 ( 1904 ), No. 2316, pj>. 

 183, 184) ■ — Rapid methods of determining water, phosphoric acid, iron and alumina, 

 lime, potash, and nitrogen are briefly described, and the significance of these various 

 determinations with reference to the use of fertilizers is briefly discussed. 



On the determination of phosphoric acid as magnesium pyrophosphate, 

 K. K. Jakvinen (Ztschr. Analyt. CJiem., 43 {1904), No. 5, pp. 279-282).— The author 

 claims that dimagnesium-ammonium phosphate is precipitated and accurate results 

 are thus assured when precipitation is effected as follows: Make the phosphoric acid 

 solution feebly alkaline with ammonia and pour the solution slowly with constant 

 stirring into a perfectly neutral solution of a mixture of magnesium chlorid and 

 ammonium chlorid (102 gm. of the former and 53 gm. of the latter per liter), using 

 about 10 cc. of the solution to each 0.1 gm. of phosphoric acid. The precipitate is 

 crystalline and forms slowly ami should carry down with it all free ammonia. 

 Otherwise trimagnesium-ammonium phosphate is formed and the results are too 

 high. 



The volumetric determination of potash in the form of double hyposul- 

 phite of potassium and bismuth, W. Kdster and M. Grcters (Ztschr. Anorgan. 

 Chem., 36 (1903), pp. 3/3-331; abs. in Bid. Soc. Chim. Paris, 3. ser., 32 {1904), No. 11, 

 ]>. 701). — This is an account of tests of Carnot's method, which is condemned a- 

 unreliable. 



The determination of nitrogen, L. Debourdeaux (Bui. Soc. Chim. Paris, ■!. ser., 

 31 (1904), No. 10, pp. 578-580). — A method is described which it is claimed converts 

 the nitrogen of the following groups of nitrogenous substances into ammonia with- 

 out mixture of ainins: Oxidation compounds of nitrogen, hydroxylamin, nitrogen 

 derivatives of which the nitrogen nucleus contains a phenol group, nitriles, cyanids 

 and double cyanids, cyanates and sulphocyanates, amids and imids in which the 

 nitrogen is not further replaced by a carbon radical, and amins with an acid radical. 



The determination is made in a modified Schloesing apparatus of glass as follows: 

 Distill the substance nearly to dryness with 50 gm. of crystallized potassium hyposul- 

 phite and 200 cc. of a solution of potassium monosulphid. The latter solution is 

 obtained by saturating a given volume of potash solution, 36° B., with hydrogen 

 sulphid and mixing this with an equal volume of untreated solution. Distill a sec- 

 ond time to remove the last traces of ammonia with 25 cc. of potash solution and 

 250 cc. of water, continuing the distillation until about 150 cc. of distillate has been 

 obtained. The ammonia is determined by titration in the usual manner. 



Estimation of nitrites in waters, J. Desfourniaux and L. Robin (Ann. ('him. 

 Anali/L, 9 (1904), pp. 6S, 69; aba. in Jour. Chem. Soc. [London], 36 (1904), No. 499, 

 II, p. 367). — Desfourniaux describes a method based on the liberation of nitrous acid 

 by salicylic acid, in the presence of potassium iodid, and titration of the iodin thus 

 set free. Robin calls attention to his own process, published in 1898, which is prac- 

 tically the same as that of Desfourniaux, acetic acid being used instead of salicylic 

 acid. 



The rendering visible of ultramicroscopic particles and their measurement, 

 with especial reference to glass colored with gold, H. Siedentopf and R. Zsig- 



