1919] AGRICULTURAL CHEMISTRY — AGROTECHKT. 809 



ployed. Tin- sulphuric acid la purified by beating tirst with potaaaluni dh'hro- 

 mate and afterwards with potassium permanganate. Instead of potassium 

 dlchromate for the oxidation of organic suits, the author employs a mixture of 

 chromic and sulphuric acids. 



Determination of free alkalis and carbonate in alkaline hypochlorite 

 solutions, M. I'mi.im i;r {-lour. I'h'inn. ct Chim., 7. ser., 18 {1918), No. 'J, pp. 

 260-272). — The method proposed consists essentially of determinations of the 

 total alkali and of the free alkali or bicarbonates, preceded by the destruction 

 of oxidising substances by hyposulphites as in the method of Mestrezat previ- 

 ously noted (B. s. if., to. p. H2). instead of adding the hyposulphite directly 

 to the alkaline liquid, the solution is first acidified and the destruction of 

 oxidizing substances brought about in the presence of potassium iodld. This 

 is considered to give much more constant and accurate results than those 

 Obtained In an alkaline medium. 



A simplification of the Mestrezat method is also proposed in which the use 

 of phenolphthaleln Is dispensed with by noting the successive color changes of 

 litmus from blue to violet and from violet to red. The first color change cor- 

 responds to the phenolphthalein test and represents the change from carbonate 

 to bicarbonate. 



The separation and gravimetric estimation of potassium, S. B. Kuzirian 

 (/'roe. Iowa Acad. Sci., 2' t (1017), pp. 5-' f 7-550). — From studies conducted at the 

 Iowa Ebrperimenl Station on the use of anilln perchlorate for the gravimetric 

 estimation of potash, the author concludes that the best results are obtained 

 when the following points are observed : 



"The exact strength of the alcohol used must ho known, and none used that 

 runs below 99.5 per cent. For every 1.5 cc. of water used for dissolving the 

 mixed chlorids, 50 cc. of absolute alcohol should be added. A weighed amount 

 of anilin perchlorate dissolved in 50 cc. of absolute alcohol must be added to the 

 dissolved chlorids drop by drop with constant shaking and set aside for one 

 hour before filtering." It is considered necessary to add the anilin perchlorate 

 slowly in order to avoid the occlusion of some of the potassium chlorid with 

 the perchlorate. If sufficient precautions are taken to prevent this occlusion, 

 a complete conversion of the chlorids into perchlorates is said to take place. 



The use of anilin perchlorate instead of perchloric acid is said to shorten 

 the process considerably, to afford the best means for direct quantitative 

 separation and estimation of sodium in the alcoholic filtrate, and to cheapen 

 the process by doing away with platinlc chlorid. 



The determination of nitrates and nitrites, W. Streckep. {Ber. Deut. Chan. 

 QeaeU., 51 (1918), No. 10, pp. 997-1004, fig. 1).—A method is described for the 

 determination of nitrites and nitrates in the same solution which includes (1) 

 the reaction between the nitrites and ammonium chlorid in which nitrogen is 

 evolved, collected In a nitrometer, and measured, and (2) the reaction between 

 nitrates and ferrous salts in which idtric oxid is evolved and collected in the 

 same nitrometer. 



A diagram is given of the apparatus, in which special precautions are taken 

 to remove the air by means of carbon dioxid. The method is also applicable 

 to the determination of nitrates alone. 



The determination of nitrites, F. IUeneht (Compt. Rend. Acad. Sci. [Pari*], 

 167 (1918), No. 10, pp. 366, 867: ab8. in ■four. Pharm. ct Chim., 7. scr.. 18 {1918), 

 No. 7, pp. 217. 218; Jour. Chan. Soc. [London], 111, {1918), No. 672, II, p. 870).— 

 The method depends upon the following reaction: NaN&+2HI=NaI+I+NO+ 

 HjO. To prevent the oxidation of the nitric oxid formed and its subsequent 

 action on hydrogen iodid, the reaction is conducted in the absence of air by 



