1910] AGRICULTURAL CHE MISTR1 AGROTECHNY. 409 



or yeast extract makes a satisfactory substitute for meal extract In the prepara- 

 tion of culture media and In the regeneration of ased agar. 



An efficient laboratory funnel for filtering neutral liquids, especially the 

 volatile organic solvents, T. B. ALDBICH (Jour. Indus, and Enffin. Ghent., II 

 (1919), No. 2, pp. /.;.'<. r,n. figs. 2).— A funnel Is described In which the fitter 

 paper is clamped securely between two plates by a screw thread bo that it 

 can net lift even when the filtration is Interrupted and the solvenl evaporates. 

 The nitration is said to be more rapid and complete than with the ordinary 

 it Buchner funnel. 



A new indicator of vegetable nature, O. Matmni (Ann. Chim. Appl. [Rome], 

 in (1918). Xo. l-'f. pp 88-86; abs. in Chem. Ab$., tS (1919), No. l. pp. /?. 18).— 

 An alcoholic extract of myrtle berries is ased as the basis of an indicator 

 which is said to he more delicate than litmus. The indicator is green in alka- 

 line solution and carmine red In add. 



Action of iodin on hypophosphorous and phosphorous acids. Application to 

 the determination of hypophosphites and phosphites, BOTES and B w/.n. 

 (Jour. 1'harm. et Chim.. 7. WT., 18 (1918). Xo. 11. pp. 321-33.',. flfft. .',).— The 

 action of iodin on hypophosphorous and phosphorous adds is discussed, and 

 modifications of the nsual lodometrlc methods for the determination of flu 

 acids are described which are said to be applicable to tbeir quantitative separa- 

 tion. 



In the determination of hypophosphorous acid by iodin in an acid medium, 

 the authors consider it unnecessary to carry the oxidation beyond the phos- 

 phorous acid stage. It was found that with a pure hypophosphite the iodin 

 required in an acid medium is exactly half that required in a medium alter- 

 nately acid and alkaline. Deviation from these proportions indicates tbe pres- 

 ence of phosphites, which can be determined by the amount of deviation. 



A study of the influence of sodium hydroxid, sodium carbonate, and sodium 

 bicarbonate in equimoleeular amounts upon the oxidation of sodium phos- 

 phite by iodin showed that tbe rapidity of the oxidation is in inverse ratio to 

 the strength of tbe alkali. The reaction is complete in 30 minutes with sodium 

 bicarbonate and in 3 hours with neutral carbonate, while with sodium hydroxid 

 it is almost negligible even after 0> hours. The details of the methods are as 

 follows : 



Determination of hypophosphorous aeirl. — One gm. of the substance Is dis- 

 solved in distilled water and made up to 100 cc. To 10 cc. of this solution are 

 added 10 cc. of sulphuric :icid (1:4) nnd 30 cc. of N/10 iodin. The flask is 

 securely stoppered) left in a dark place for from 8 to 10 hours, and the 

 solution then titrated with N/10 hyposulphite. 



Determination of phosphorous aciil. — To 10 cc. of phosphite solution pre- 

 pared as above are added 10 cc. of a 5 per cent solution of sodium bicarbonate 

 nnd 20 cc. of N/10 iodin. After standing for 2 hours in a closely stoppered 

 flask. 10 cc. of 10 per cent acetic acid is added and the solution titrated with 

 N/10 hyposulphite. 



In a mixture of salts of the different acids of phosphorus, the hypophos- 

 phites and phosphites are determined separately, nnd the phosphates then 

 determined by precipitation as magnesium-ammonium phosphate. The results 

 obtained in this way can be checked by oxidizing another portion of the sub- 

 stance with nitric acid and determining the orthophosphorlc add thus formed. 



Volumetric estimation of the sulphion, R. Howoen (Chem. Xews. in (1918). 

 Xo. SOGS, p. SS3). — A rapid method for the estimation of tbe SO, ion is outlined 

 which is based on the decomposition of soluble alkaline sulphates by insoluble 

 barium carbonate, generating alkaline carbonate which can be estimated by 



