CONVENTION OF OFFICIAL AGRICULTURAL CHEMISTS. 113 



associates, L. S. Munsou and L. M. Tolman, a consideration of special 

 methods used in the analysis of .sugar beets and raw sugars, and rec- 

 ommendations of changes in the official methods, inchiding the su])sti- 

 tution of the German official method for Clerget's method for the 

 determination of sucrose and the adoption of the method of direct 

 weighing of the cuprous oxid. and of several provisional methods, one 

 of which was the inversion at ordinary temperatures with hydrochloric 

 acid in the proportions used in the German official method. Further 

 work along the lines followed during the year was recommended. 



Mr. Munson presented in detail the results of his investigations on 

 methods for determining reducing sugars. The work was conducted 

 with a view to simplifying methods and increasing the accuracy of 

 such work. The results showed that the reduction method, in which 

 the suboxid is weighed directly, is accurate. Encouraging results were 

 obtained in experiments to devise a single copper solution for use under 

 uniform conditions with all reducing sugars. Conditions modifying 

 reduction were also studied. 



Mr. Tolman read a paper giving the results of his investigations on 

 optical methods for the determination of sucrose. In inversion at 

 ordinary temperatures very satisfactory results were obtained in the 

 use of hydrochloric acid in the proportions given in the German official 

 method. Accurate results were ol)tained in the use of citric acid for 

 the inversion of sucrose in the al)sence of acetates. Levulose was not 

 decomposed nor its rotary power a'H'ected l)y this method, which was 

 pointed out as of value in the examination of honey. 



TANNIN. 



The work done during the year on this subject consisted of compari- 

 sons of single and double filter papers in the determination of soluble 

 solids in chestnut and quebracho extracts and of the distillation, 

 Kohnstein-Simand, and charcoal methods for the determination of 

 acids in a union liquor. Results were reported by the referee, W. H. 

 Teas, who recommended several changes in the official methods, 

 including an omission of the moisture determination in extracts, evap- 

 oration under identical conditions, and the use of single instead of 

 double filter papers in the determination of soluble solids, and sug- 

 gested for future work additional experiments on soluble solids, acid 

 determinations, and on the amount of extract to be taken for analysis. 

 Studies of a proposed modification of the charcoal method and of the 

 correction method for the tannin absorption of the filter paper adopted 

 by the International Association of Leather Trades Chemists were also 

 suggested. A charcoal method for the determination of total acidity 

 in liquors was adopted provisionally. 



A letter from H. K. Proctor, referring briefly to the proceedings of 

 the last meetino- of the International Association of Leather Trades 



