p 



1920] AGRICULTURAL CHEMISTRY AGROTECHNY. 315 



coniiiKni oxidizins asents, and suu^cst a method of dt'tcriuiniriK the true value 

 of vanilhi whicli is tliouglit to be more accurate than the Ofllcuil Method. 



The method proposed involves the use of the clarifying agent of Folin and 

 I>enis (K. S. R., 28, p. 807) and the coloring agent of Estes (E. S. R., 37, p. 

 12). The technique is as follows: 



To 5 cc. of the vanilla extract in a 100 cc. flask are added 75 cc. of water 

 and 4 cc. of lead acetate solution (containing 5 per cent basic and 5 per cent 

 neutral lead acetate). The solution is made up to 100 cc, filtered, and 10 cc. 

 of the tilt rate placed in a 50 cc. flask. To this are added 15 or 20 cc. of water 

 nnd (>.;> cc. of the Estes reagent (mercury dissolved in twice its weight of con- 

 centrated nitric acid and diluted with 25 times its weight of water). A 1 cc. 

 portion of the 1 per cent standard vanillin is treated in the same manner, and 

 both flasks are then placed in boiling water for 20 minutes, made up to 

 volume, filtered if necessary, and compared in a colorimeter. 



The solubility of raw cellulose in ununoniacal copper hydroxid and the 

 ntilization of this solubility for the valuation of feeding; stuffs, P. IMacii 

 (LmuUr. Vers. Stu., 91 (WIS), No. 3-Jf, pp. 137-155).— Thin is a discussion of the 

 value of the method desci'iljed by the author and P. Lederle^ for dis- 

 tinguishing between raw and hydrolyzed cellulose by treating the material 

 with jimmoniacal copper hydroxid and precipitating the dissolved cellulose 

 with alcohol and acetic acid. In addition to the original use of the method, 

 further ai)plications are suggested such as the testing of new feeding stuffs; 

 the quantitative determination of chaff-containing feeding stuffs; tlie study of 

 the eft'ect on feeding stuffs and foods of such influences as witlu>ring, storage, 

 fermentation, etc.; the study of the relation between raw cellulose and nitro- 

 gen-free extract ; and the examination of raw material for textile and paper 

 manufactui'e. 



Analytical applications of iodin reactions with nonsaturated sub- 

 stances. The Hiibl index and pseudo-indexes of essential oils, R. Huerre 



(Jour. Phanii. ct Ckiiu., 7. so:, 20 {1919), Nos. 7, pp. 216-22',; 8, pp. 250-257; 

 9. pp. 273-281; ahs. in Chcm. Ah.^., 11, {1920), No. 1, pp. 92).— It is pointed out 

 that with essential oils the Hiibl iodin number increases with the excess of 

 iodin iised, reaching a maxinuim at a definite optimum for excess which is 13 

 parts of iodin to 1 of oil of turiK'utine and 14 : 1 for oil of cedar. If Ilul)rs 

 solution is used, the iodin number of an essential oil should consequently be 

 defin(>d as the maximmn quantity of iodin which can be absorbed by 100 

 gm. of the oil in the presence of mercuric chlorid and of the optimum excess 

 of the iodin. 



As a substitute method, the author suggests the use of an alcoholic solution 

 of iodin, which in contact with a solution of the essential oil in chloroform 

 undergoes a loss of iodin determined l)y titration with thiosulphate. For the 

 constant thus determined the name "pseudo-index for iodin" is suggested, 

 and defined as the maximum amount of iodin which disappears in a two- 

 hour contact with 100 gm. of the soluti(»n of the turpentine in alcohol Miien 

 using the optimum excess of iodin. 



A now method for detecting adulteration in butter and for estimating 

 fats of the coconut group, G. V. B. rFiusroiR ( ADdlijst, J,5 {1920), No. 526, pp. 

 2-7, ifig. 1). — The chief difference between this ir.ethod and those in general use 

 consists in the treatment of the A-olatile acids. The neutral soaps representing 

 the total volatile fatty acids obtaintnl from the sami)le by the method described 

 by Blichfeldt (E. S. R., 41, p. 412) are converted into the corresi)onding 

 acids and separated into two groups depending upon their solubility or 



I 



iLandw. Vers. Sta., 90 (1917), pp. 269-289. 



