806 EXPERIMENT STATION EECOED. [Vol.36 



It is pointed out that the present application of the Cottrell precipitator is 

 the first to be used for the precipitation of a product which has been purposely 

 volatilized with a view to its recovery in this way. 



The determination of total phosphorus in bone ash, F. PrLz {Ztschr. 

 Landw. Versuchsw. Osterr., 19 (1916), No. 2, pp. 57-61 ) .—Comparative analyti- 

 cal data show that as accurate results can be obtained when the sample is 

 oxidized with a mixture of sulphuric and nitric acids as when nitric acid alone 

 is used. The preliminary precipitation as ammonium phosphomolybdate is con- 

 sidered not to be absolutely necessary for reliable results. These modifications 

 are deemed to be of some importance in view of the scarcity and high price of 

 the chemicals necessary in these operations. 



A colorimetric method for the determination of the CO2 percentage in air, 

 H. L. HiGGiNS and W. McK. Mareiott {Jour. Amer. Chem. Sac, 39 (1917), No. 

 1, pp. 68-71). — A method which depends on determining the reaction of a solu- 

 tion of sodium bicarbonate after passage of air until the solution is saturated 

 with carbon dioxid is described in detail. The reaction of such a solution will 

 depend on the relative amounts of the alkaline bicarbonate and carbonic acid 

 present. This in turn depends on the pressure of the carbon dioxid in the air 

 with which the mixture has been saturated and is independent of the volume 

 of air passed through the liquid. High pressures of carbon dioxid change the 

 reaction of the solution toward the acid side, while low pressures have the 

 reverse effect. 



The indicator used is phenolsulphonephthalein and the standards, acid potas- 

 sium phosphate (KH2PO4) and alkaline sodium phosphate (Na:HP04). 



The method is not applicable in the presence of acid or ammonia fumes. 



On the determination of small amounts of arsenic with special reference 

 to the procedure according to Smith, K. Beck and Merkes (Arb. K. Gsndht- 

 samt., 50 (1915), No. 1, pp. 38-49, pis. 2, figs. 2). — This is a general review and 

 discussion of the methods proposed for the determination of minute quantities 

 of arsenic. 



The method described by Smith (E. S. R.. 28. p. 24) is deemed very satisfac- 

 tory and to yield very accurate results, especially in the examination of foods 

 and food products. The procedure is easy to manipulate and reqiiires a mini- 

 mum of time and only a very small sample, this being an especially great ad- 

 vantage with organic material. 



It is indicated that the simple colorimetric method is accurate for differen- 

 tiating amounts of arsenic of 0.002, 0.005. 0.01, 0.02, 0.03, and 0.04 mg. For 

 greater accuracy the procedure should be used only as an indicator, the ultimate 

 determination being made either gravimeti'ically or titrametrically, preferably 

 the latter. 



Some analytical data of the arsenic determined in various meat, plant, and 

 yeast extracts, caviar, hydrogenated oils, and gelatin are submitted. 



A new procedure for the determination of methyl alcohol in the presence 

 of ethyl alcohol, G. Retf (Arb. K. Gsndhtsamt., 50 (1915), No. 1, pp. 50-56).— 

 A procedure which depends on the formation of trimethylsulphiniodid and sub- 

 sequent titration with silver nitrate and retitration with ammonium thiocyanate 

 Is described in detail, as well as a slightly modified procedure for determining 

 methyl alcohol in brandy in which the acids, esters, aldehydes, and acetone 

 usually present do not interfere. Analytical data submitted indicate the accu- 

 racy of the procedure. 



The determination of raffinose in the presence of sucrose by means of 

 double inversion with two special yeasts, H. Pellet (Bui. Assoc. Chim. 

 Suor. et Distill., S3 (1916), No. 10-12, pp. 255-262) .—The unreliability of the 

 usual procedure of polarization before and after inversion with add in th(? 



