RECENT WORK IN A(;RICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY. 



Nitron as a microchemical reagent, II. L. Visser {Vlicin. Wcekblad, 3 

 (1906), pp. 743-7^6; (lbs. in Ghent. Zenthl, 1907, I, l^o. Jf, p. 302; Jour. ,Soc. 

 Chcni. Indus., 26 (1907). No. ^, pp. 167, 168; Jour. Chem. 80c. [London], 92 

 (1907), No. 535, II, p. 394). — The author recommends that instead of weighing 

 the nitron nitrate in determining nitric acid the determination be made by com- 

 paring the depth of the layer of precipitate with that of a corresponding 

 l)recii)itate from a solution of known content of nitric acid in glass tubes of 

 equal diameter. 



It is stated that nitron also forms almost Insoluble salts with nitrous, cldoric, 

 perchloric, oxalic, and salicylic acids, which may be distinguished under the 

 microscope by differences of crystalline form. " Nitron may also be used for 

 the microchemical detection of saccharin if the latter be first converted into 

 o-sulphaminobeuzoic acid by the action of dilute alkali." The characteristic 

 crystalline form of this substance is easily detected with the mi(!-roscope. 



Note on the determination of nitrogen by the Jodlbaur method, H. Volk- 

 HOLZ (Chem. Ztg., 30 {1906), p. 370; ohs. in Zfsclir. Angcw. Che in., 20 (1907), 

 No. 23, pp. 960, 961). — The author simplifies and shortens this method by 

 adding the zinc dust in small portions and with vigorous shaking to the hot 

 acid solution. 



Determination of nitrous acid and its separation from nitric acid, G. 

 Maderna and G. Coffetti (Abs. in Chem. Ztg., 31 (1907), No. 29, p. 375; 

 Analyst, 32 (1907), No. 375, p. 23Jt). — ^The method proposed is based upon the 

 fact that in the presence of acetic acid, or, preferably, citric acid, nitrous 

 acid is reduced to nitric oxid by ferrocyanids, and the liberated gas may be 

 collected and measured. Under these conditions nitric acid does not react with 

 ferrocyanid. 



Detection of nitric and nitrous acids, II. W. Wagner (Pharm. CcntralhaUe, 

 J,8 (1907), pp. 5-7; abs. in Jour. Chem. Soc. [London], 92 (1907), No. 533, II, 

 p. 196). — A slight modification of Sprengler's phenol test is recommended. 



On the method of separating potassium from sodium as chloroplatinates, 

 J. MoRozEwicz (Bui. Acad. 8ci. Cracorie, 1906, pp. 796-S03; abs. in Chcin. Abs., 

 1 (1907), No. 8, p. 57:2).— Eighty per cent alcohol is considered preferable to 

 absolute alcohol for washing out the sodium chloroplatinate. The polarizing 

 microscope will detect doubly refracting salts in a drop of the slowly evaporated 

 aqueous solution of the potassium chloroplatinate and thus determine its 

 purity. 



The estimation of free acids in superphosphates, J. Van Dobmael (Bui. 

 »S'oc. Chini. BeUj., 21 (1907), No. 3. pp. 103-115; abs. in Jour. 80c. Chem. Indus., 

 26 (1907), No. 8, p. Jt2.'t; Analyst, 32 (1907), No. 37/,, p. 182).— The method ]>ro- 

 posed embodies those of Ilerzfelder and Thomson and is based upon double 

 titration with fourth-normal sodium hydroxid solution of the ether or alcohol 

 extract (evaporated to dryness and taken up in water) of the dried super- 



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