RECENT WORK IN AGRICULTURAL SCIENCE. 



CHEMISTRY. 



Ne-w method for the gravimetric determination of reducing 

 sugars, based upon the use of the centrifuge, P. CHArELLE {Rev. 



Chun. Analyt. et Appl., o {1000), No. 2, pp. J4-lf.J^).—\t is stated that 

 the quantit}^ of oxid of copper precipitated by Fehling's solution is 

 not exactly proportional to the sugar used, but is a function of the 

 dilution of the solution and excess of copper. When working with 

 constant dilution, the only cause of trouble is the excess of copper, 

 and it is easy to determine the value of that. A measured quant it}' 

 of sugar solution insufficient to obtain complete reduction and 25 cc. 

 of Fehling's solution are used. The total volume is then made up to 

 37i cc. 



The tubes containing the mixed solution are heated for 3 or -i minutes 

 in a calcium chlorid Imth at 108 to 110^. They are then whirled in a 

 centrifuge, and the copper adheres to the sides. The liquid is decanted 

 and the copper precipitate washed with water, dried and weighed. 

 It is stated that when 250 mg. of copper precipitate are obtained 

 duplicates agree within \ mg. A table is given, showing the amounts 

 of glucose, lactose, sucrose, etc., corresponding to different weights of 

 cuprous oxid. 



In the succeeding numl)er of the journal (No. 3) the application of 

 this method to the determination of the sugars in milk, blood, wine, 

 urine, etc., is considered. — h. snyder. 



Simple and rapid method for the determination of the iodin 

 number of fats, J. Bellier {Rei\ Chhii. Analyt. d Apj)I.. o {1900), 

 No. J4., pp. 128-13Ji). — Hiibrs method is considered as requiring too 

 much time. The attempts to simplify the method by Wys and others, 

 are noted. The author uses a solution containing both iodin and bro- 

 min dissolved in 'acetic acid; 50 gm. of iodin and 32 gm. of bromin are 

 dissolved in 950 cc. of acetic acid. The solvent for the fatty bodv is 

 composed of chloroform, mercuric chlorid, acetic acid, and potassium 

 iodid. One gram of material is dissolved and the bromin-iodin solu- 

 tion added until a permanent coloration for 5 minutes is secured, and 

 the number of cc. of solution used gives directly the iodin number. It 

 is claimed that the results ol)tained are practically the same as those, 

 b}^ the Hiibl method. The iodin number of a few oils as obtained by 

 this method is given. — h. snydek. 

 106 



