1919] AGRICULTURAL CHEMISTRY — AGROTECHNY. 113 



The method, which Is described La detail, is said to have given results In 

 the analysis of alkaline hypochlorid solutions In which the chlorin has heeu 

 combined with hyposulphite, as previously suggested (B. S. R., 39, p. 506). 

 The total carbonic arid can be verified by the gasometrlc method (E. S. R., 39, 



p. 205). 



The determination of carbon dioxid in carbonates, D. D. Van Sf.ykk {Jour. 

 Biol. Chem., 86 (1918), No. 2, pp. 851-35/,, fig. 1).— The method described was 

 devised primarily for use in determining carbonate in bones which had been 

 dried and pulverized but not ashed. It is considered to be applicable to all 

 carbonates, soluble or insoluble, in the absence of acids, such as hydrogen 

 sulphid, that are highly volatile from water solution. The principle of rapid 

 extraction of carbon dioxid from solution by means of reduced pressure, 

 previously noted (E. S. R., 37, p. S04), has been combined with the precipi- 

 tation of carbonic acid by standard barium hydroxid solution and titration of 

 the excess of hydroxid. 



Volumetric determination of sulphates, Vansteenbebghe and BAUZIL {Ann. 

 Chiin. Anal /it., 28 (1918), No. 10, pp. 210-214).— The method consists essentially 

 of a preliminary precipitation of the alkaline earth bases, a part of the phos- 

 phates, etc., by an excess of sodium carbonate. The sulphates are then pre- 

 cipitated in acid solution by a known volume of barium chlorid. The excess 

 of barium chlorid is precipitated as barium carbonate with sodium carbonate 



N 

 and determined by alkalimetry with the use of - . hydrochloric acid. 



The method is said to be rapid and accurate and applicable to solutions of 

 metallic sulphates, as well as to the various body fluids (urine, blood, etc.). 



The determination of tyrosin in proteins, C. O. Johns and D. B. Jones 

 {Jour. Biol. Chem., 36 (1918), No. 2, pp. 819-322).— -An investigation of the 

 method of Folin and Denis for the determination of tyrosin (E. S. R., 28, p. 

 805) is reported from the Bureau of Chemistry of the U. S. Department of 

 Agriculture. 



It has been found that tryptophan is completely decomposed during the hydro- 

 lysis of proteins with hydrochloric acid and that the decomposition products 

 do not interfere with the determination of tyrosin. It has also been shown that 

 oxyprolin does not interfere with the determination. Since tyrosin is decom- 

 posed to some extent during hydrolysis, it is not considered of advantage to 

 continue the hydrolysis more than 12 hours. 



The optical dispersion of oils from an analytical point of view, P. J. Fbyeb 

 and F. E. Weston (Analyst, 48 (1918), No. 510, pp. 311-317).— Tables are given 

 of the dispersion values at 40° C. of various oils and a few hydrocarbons, and of 

 the effect of free acidity upon the dispersion of drying oils and of heat upon the 

 refraction and dispersion of drying oils. 



The dispersive power of fatty oils and fats was found to be inferior in dis- 

 criminative value to the refractive index, practically all the oils and fats, with 

 the exception of coconut, linseed, and tung oils, giving very similar dispersions. 

 Coconut oil gave a distinctly lower, and linseed a higher, dispersion than the 

 average. Free fatty acidity had little effect on the dispersive power. Oxidation 

 increased both the refractive index and the dispersion, and polymerization in 

 general increased the activity and lowered the dispersion. 



The autooxidation of sugars, L. Bekczelleb and E. Szego (Biochem. Ztsrfn:, 

 84 (1917), No. 1-2, pp. 1-36). — A study is reported of the autooxidation of 

 sugars in alkaline solutions in the presence of air, with and without the addi- 

 tion of various substances. Analogies are drawn between the oxidation of 

 sugars in vitro and in vivo. 



