1919] AGRICULTURAL CHEMISTRY -AGROTECHNY. 413 



(/icier vinegar, it is pointed om that since acetic acid is tunned l>y the oxidation 

 of acetylmethylcarbinol, the Duclaux method (or the detennioatioa of alooholi 

 is unreliable for the determination of ethyl alcohol in saccharin sorghum sllai 

 If acetylmethylcarbinol Is found to be present in the fresh silage made from 

 field crops, the authors consider that it will be necessary to modify the m e th od s 

 fur the determination of sugars and of alcohols In silage. 



Modifications of Benedict's and Folin's quantitative sugar methods, 11. D. 

 IIaskins (Jour. Biol, chiiii., 37 (1919), No. 2, \>i>. SOS, 894). — The author has 

 substituted sodium tblocyanate for potassium thlocyanate In the Benedict 

 method (B. S. It.. -'>, p. 15) for determining sugar in urine and in Folin's modifi- 

 cation of this method (E. S. R., 3S, p. 014). Benedict's solution prepared with 

 the substitution of equivalent amounts uf sodium thlocyanate for the potassium 

 salt proved to be a perfect substitute, but in the preparation of Folin's mixture 

 it was found that correct titrations could be obtained only by reducing some- 

 what the amount uf sodium thlocyanate and usiug periods of boiling half as long 

 as those originally recommended. 



New titration method for the determination of uric acid in urine, J. L. 

 Mokkis (Jour. Biol. Chem., 81 (191D), No. 2, pp. 231-238).— A volumetric method 

 fur the determination uf small amounts of uric acid in urine is described winch 

 is based upon the precipitation of uric acid as the zinc salt and a single direct 

 titration with permanganate in a solution made alkaline with sodium bicar- 

 bonate. The end-point used is the blue starch lodid color. The procedure, which 

 requires from 30 to 40 minutes for the complete determination, is said to be 

 entirely satisfactory for urine, and to give with the usual blood filtrate obtained 

 by precipitating proteins with dilute acetic acid results agreeing with those 

 obtained with the colorimetric method. 



Detection of methyl alcohol, G. Math (Zt.schr. Unternuch. Nahr. u. 

 Qemusmtl., 35 (1918), No. //-J, pp. 179-183). — The author discusses various 

 methods for the detection of methyl alcohol and describes the following proce- 

 dure. which depends upon the use of o-dioxybenzol or its derivatives: 



A leu cubic centimeters of the solution to be tested are distilled, and 1 cc. of 

 the distillate is oxidized with 1 cc. of sulhpuric acid (1 : 3) and 8 cc. of a 0.3 per 

 cent solution of permanganate. At the end of 10 minutes the solution is filtered, 

 and 20 cc. of the filtrate Is mixed with 2 drops of ferrous sulphate solution and 

 a few crystals of dioxybenzol or guiacol. After shaking thoroughly. '1 cc. of 

 concentrated sulphuric acid is poured slowly down the side of the tube. In the 

 presence of formaldehyde a violet red ring is formed between the two layers. 

 With the use of guiacol carbonate and ferric chlorld in place of guiacol and 

 ferrous sulphate, a raspberry colored ring is formed in from 3 to 5 minutes. 



Both tests are applicable to the detection of formaldehyde in milk. The 

 author considers the colored substances formed to belong to the group of 

 a urines. 



Lead in pharmaceutical zinc oxid, W. D. Collins and YV. F. Clakkk [Jour. 

 Indus, and Engin. Chan., 11 (1919), No. 2, pp. 138, 189). 



A special bleaching powder for use in hot countries, T. Hli iik, J. L. SMITH, 

 and J. Ritchie (Jour. Sot: Chan. Indus., 37 (1918), No. 28, pp. S11T-818T). — 

 The treatment found most successful in preventing deterioration in bleaching 

 powder at tropical temperatures consists in mixing the bleaching powder, which 

 should contain as low a percentage of moisture as possible, with one-fourth 

 more than the theoretical amount of freshly ignited quicklime necessary to 

 absorb the moisture. The product Obtained, if suitably packed in air-tight con- 

 tainers, is said to withstand any temperature likely to be encountered in the 

 Tropics. This treatment is considered specially advisable when the bleaching 



