AGEICULTUEAL CHEMISTKY AGROTECHNY. 109 



Up with water to the mark, well mixed, and allowed to subside for a few 

 minutes. It is then filtered through a dry filter and the excess of the silver 

 determined in an aliquot portion of the filtrate (100 cc.) by Volhard's method." 



Detection of small quantities of sulphur in inorganic and organic com- 

 pounds, E. Deussen (ZtscJir. Angew. Chem., 23 {1910), No. 27, pp. 1258-1260; 

 abs. in Jour. Chem. 8oc. [London], 98 (1910), No. SlJf, II, p. 750). — The sub- 

 stance under examination, for example, 2 barley berries, is pulverized and mixed 

 with 0.1 gm. sodium carbonate and small cuttings or scrapings of a 9 cm. 

 diameter filter paper, to the mixture is added a few cubic centimeters of water, 

 and the mass dried over an alcohol flame. The dry residue thus obtained is 

 titurated with a pestle, with 0.2 gm. of sodium carbonate. The mixture is then 

 transferred to an extraction thimble or cartridge, which is wound around three 

 or four times with a platinum wire attached to a glass rod, and the whole 

 heated for from 6 to 10 minutes in the inner flame of a blowpipe heated by 

 Kahlbaum's molecular benzene. The fused mass so obtained Is dissolved in 

 water and the filtrate therefrom examined for sulphid by means of all^aline 

 lead solution (10 drops of normal lead solution, 70 cc. of water, and 20 cc. of 

 normal sodium hydroxid solution). The process is modified somewhat when 

 fluorids are present. 



Gravimetric estimation of sulphuric acid in the presence of alkali metals. 

 Y. Kato and I. Noda (Mem. Col. /Set. Engin. Kyoto, 2 (1909-10), pp. 217-228; 

 abs. in Jour. Chem. 8oc. [London], 98 (1910), No. 576, II, p. 895). — "The con- 

 centration of a seminormal solution of sulphuric acid was determined gravi- 

 metrically both in the absence of, and in the presence of, equivalent solutions 

 of the chlorids of potassium, sodium, and ammonium. Determinations were 

 also made with varying concentrations of the haloid salts, and with more dilute 

 solutions of sulphuric acid. 



" Potassium chlorid caused the greatest error in the determination. The 

 ratio (R) of salt to acid and the percentage difference (D) between the results 

 obtained in the absence of, and in the presence of, potassium chlorid are con- 

 nected by the equation : logD=«logR+K. where K is a constant. This is similar 

 to the ordinary adsorption formula, so that it is probable that potassium sul- 

 phate is adsorbed during the precipitation of the barium sulphate. Adsorption 

 is diminished, but not completely, by diluting the solution. No adsorption talies 

 place in the presence of magnesium chlorid." 



Volumetric estimation of manganese, Z. Karaoglanoff (Ztschr. Analyt. 

 Chem., 1,9 (1910), No. 7, pp. 419-1,24; abs. in Jour. Chem. Soc. iLondon], 9S 

 (1910), No. 577/, //, p. 75//).— This is a modification of Volhard's method (hot 

 titration of manganous sulphate with permanganate in presence of zinc sul- 

 phate), which does not yield good, results when iron is present. If nitrate is 

 taken instead of sulphate and about two or three times as much ferric nitrate, 

 or, better still silver nitrate, is added, the results with the method are good. 

 Free nitric acid or zinc, aluminum or barium nitrates, or titrating without an 

 additional salt cause inaccurate results. 



Analysis of calcium cyanamid, A. Monnier (Chem. Ztg., 35 (1911), No. 67, 

 pp. 601, 602; abs. in Jour. Soc. Chem. Indus., SO (1911), No. 13, pp. 821, 822).— 

 The cyanamid nitrogen was determined by the Friderich method, which is based 

 on the conversion of the cyanamid into urea by the agencies of acids, as fol- 

 lows : " One gm. of the fertilizer is agitated for 2J hours with 100 cc. of water, 

 the mixture filtered, and 2.5 cc. of the filtrate, with addition of 10 cc. of formic 

 acid, are evaporated nearly to dryness ; the residue is taken up with 25 cc. of 

 water, and 10 cc. of the solution are treated with sodium hypobromite in a 

 ureometer, comparison being made with a 0.5 per cent solution of pure urea." 



