210 EXPERIMENT STATION RECOED. 



The iodin reactions for starch, W. Harrison (Proc. Chem. Soc. London, 26 

 (1910), No. 376, pp. 252, 253; abs. in Jour. Soc. Chem. Indus., 29 {1910), No. 

 22, p. 1335; Chem. Ztg., SJf (1910), No. 1J,2, p. 126 J^) .—From, this work it appears 

 that it is unnecessai-y to have an iodid present wlien conducting this test. 

 In the presence of silts or some dikite acid, the bhie color obtained in the 

 reaction is decidedly darker. On adding alcohol to the solution it takes on a 

 variety of transitory colors which range from violet to yellow, a reversion to the 

 original color being brought about by adding water. By washing iodized starch 

 with pure water, all the iodin can be removed, from which the author concludes 

 that starch plays the role of a protective colloid. Under certain conditions it is 

 possible to produce the reaction for dextrins and starch celluloses with starch, 

 and the author believes that dextrins and starch celluloses are simply different 

 colloidal states of starch, and do not represent different compounds. 



An improved (Scherer) reaction for inosit, E. Salkowski (Ztschr. Physiol. 

 Chem., 60 (1010), No. 6, pp. J,78~.',S1; ahs. in WchnseJir. Bran., 28 (1011), No. 8, 

 p. 95). — A little of the inosit is placed upon a porcelain crucible cover, dissolved 

 in from 1 to 2 drops of nitric acid (specific gravity 1.2), then 1 drop of a 10 

 per cent potassium chlorid solution and 1 drop of a 1 to 2 per cent platinic 

 chlorid solution are added, and the solution carefully evaporated by blowing 

 and rotating. Inosit gives a pink to a brick-red coloration. 



Contribution to the biochemical detection of glucosids decomposable by 

 emulsin, E. M. Boukquelot (Pharm. ZcntralJiaUc. 51 (1910), No. Jp\ pp. 1086- 

 1080; abs. in Chem. Abs., 5 (1011), No. 5, pp. 967, 968).— A discussion of new 

 methods for studying the activity of emulsin. The glucosid employed was 

 salicin. 



Estimation of formic acid, A. F. Joseph (Jour. Soc. Chem. Indus., 29 (1910), 

 No. 20, pp. 1189, 1190; abs. in Chem. Abs., 5 (1911), No. 3, pp. U5, .^//6).— The 

 method is based on the oxidation of the acid or formate with bromin, and then 

 estimating the amount of hydrobromic acid or bromid produced. This is re- 

 ferred back to formic acid. 



Simple method for determining formaldehyde, F. Herrmann (Chem. Ztg., 

 35 (1911), No. Ii, pp. 25, 26; abs. in Chem. Abs., 5 (1911), No. 6, pp. 1158, 

 1159). — To a gla-ss-stoppered 150 to 200 cc. Erlenmeyer flask, which contains 

 from 4 to 4J gm. of the formaldehyde solution, add about 3 gm. of ammonium 

 chlorid, and then run in as quickly as possible amid shaking 25 cc. of double- 

 normal sodium hydrate solution. After allowing the mixture to cool at room 

 temperature, add 50 cc. of water which contains 4 drops of a 1 per cent methyl 

 orange solution, and titrate back with a normal solution of sulphuric acid. 

 The difference obtained between 'the two normal solutions represents the sodium 

 hydrate consumed for the production of hexamethylamintetramin, and when 

 multiplied by 0.06 represents the formaldehyde in grams in the sample. Where 

 much acid is present in the formaldehyde a correction for the acid must be made 

 by titrating with tenth-normal sodium hydrate and against phenolphthalein. 



A method of determining free and com.bined oxalic acid in plants, W. D. 

 McAbee (Pure Products, 7 (1011), No. 3, p. i'/'/).— The method is as follows: 



" Dry the substance, usually 1.50 gm., in a water oven, pulverize and extract 

 with four 25 cc. portions of acidified alcohol (10 cc. concentrated hydrochloric 

 acid to 90 cc. alcohol). In extracting, the alcohol should be poured over the 

 substance, which is heated on the water bath, allowed to stand for half an hour, 

 and filtered. The residue is then transferred from the paper and extracted 

 three more times. Add 5 cc. dilute sulphuric acid to the combined extractions, 

 evaporate to 50 cc. volume, and filter. Exactly neutralize with sodium hydroxid, 

 make strongly acid with acetic acid, add calcium chlorid solution, let stand 

 overnight, filter, ignite, and weigh as calcium oxid." 



