AGRICULTURAL CHEMISTRY — AGROTECHNY. 113 



" Slightly acidify 25 cc. of the extract, if alkaline, with sulphuric acid, add 

 25 CO. of water, and distill to dryness. To the distillate, containing the vanilla 

 and coumariu, add 15 to 20 drops of 1 : 1 potassium hydroxid, hastily evaporate 

 the distillate to 5 cc, and transfer to a test tube. Heat the test tube over a 

 free flame until the water completely evaporates and the residue fuses to a color- 

 less, or nearly colorless mass. The reaction previously described will have 

 occurreil. Cool the melt and dissolve in a few cubic centimeters of water. 

 Transfer the solution to a 50 cc. Erlenmeyer flask and acidify slightly with 25 

 per cent sulphuric acid. The amount of solution should not be over 10 cc. 

 Finally distill the solution into a test tube containing 4 or 5 drops of neutral 

 0.5 per cent ferric sulphate or ferric chlorid. If coumarin is pi'eseut in th«; 

 original extract, an amethyst or purplish color wlil develop, the intensity being 

 directly proportional to the amount of coumarin present. 



"Vanillin and other normal constituents of vanilla extract do not interfere 

 with the method." 



The estimation of furfurol by means of Fehling's solution, L. Eynon and 

 J. IL Lane (Analyst, 37 {1912), 'So. J/Jl, pp. Jft-'/G). — ^^\. series of exi>eriments 

 was conducted with Flohil's method, previously noted (E. S. R., 25. p. lOS), 

 to determine the influence of various concentrations, both of furfurol and 

 sodium chlorid, and to ascertain the degi-ee of accuracy of the method. 



It was found, contrary to the statement of Flohil, that the copper-reducing 

 power of furfurol is not independent of the concentration, and therefore there 

 api)ears no groimd for the assumption that a simple stochiometric relation 

 between the furfiu'ol and copper exists. The method yielded good results 

 when corrections for concentration were applied, but in a few instances the 

 error was from 3 to 5 per cent. Flohil's statement that the unreduced copper 

 in the liquid after boiling may be determined by Schoorl's iodometric method 

 was confirmed. 



Examination of certain milk testing apparatus, H. Tiemann (Molk. Ztg, 

 lllUdcshcini], 25 {I'JlJ), Xo.';. 32, pp. r,9I, 592; 33, pp. G05-6J08) .—The forms of 

 apparatus tested in this work were the optical butyrometer and the catalase 

 tube of Lobeck (B. S. R., 23, p. 13). the Gloria centrifuge, the neu-sal apparatus, 

 and an automatic pipette for measuring off alcohol. All of this apparatus is 

 in use in Germany. 



The determination of the acidity of milk, O. Rammstedt (Chem. Ztg., 85 

 (1911), No. 131, pp. 1218, 1219; abs. in Zischr. Angew. Clicm., 25 (1912), No. 

 9, p. Ii3()). — This should be done on the basis of the Soxhlet-ITenkel criterions, 

 both on account of uniformity and exactness. 



The methods for determining fat most frequently used in milk chemistry, 

 O. VON SoBBE (Molk. Ztg. [HUdeshcin^. 25 (1911), Nos. J,5, pp. 8.'i9, 850; .',6, 

 pp. 863, 86 'i; 1ft, pp. 881, 888; ^8, pp. 903, 90//).— The methods described are 

 the Wollny refractometric, Gottlieb-Rose, Soxhiet specific gravity (areometric). 

 acid butyrometric of Gerber, sal, " neu-sal," Sichler's sin-acid, and Hammer- 

 schmidt's precipitation methods. 



Do volatile fatty acids occur in fresh, whole milk? W. D. Koopek (Milchw. 

 ZcnthL, 7 (1911), No. 7, pp. 312-31',).— Accordiug to the author, no volatile 

 fatty acids occur in pure fresh butter fat, and according to this it would nat- 

 urally be expected that none would occur in fresh milk. He finds, however, 

 that by distilling with steam fresh milk which contains an addition of a little 

 phosphoric acid a distillate containing fatty acids consisting chiefly of butyric 

 acid is obtained. Skim milk with very little fat was found to yield a higher 

 percentage of acid than the distillate from cream. The original acidity of milk 

 also had some influence upon the final results. 



