CONVENTION OF OFFICIAL AOKICULTUKAL CHEMISTS. 441 



was not claimed that sucrose could be determined ])y it with absolute aocuracj- in the 

 case of a dark molasses, nevertheless the method was believed to insure increased 

 accuracy, and the association was asked to give it consideration. 



TANNIN. 



Cooperative tests of methods for tho deteriiiination of solii})le solids 

 and acidity in extracts were reported b}' the referee and several recom- 

 mendations were made. The proposed changes in methods were 

 referred to the referee for next yenv for consideration. 



Report of referee, CI. A. Kerr. — Samples of a fluid chestnut extract and a (|ue- 

 bracho extract were sent to 16 analysts for the purpose of making comparative tests 

 of the single filter paper in determining the soluble solids, investigating the correction 

 for filter paper absorption adopted by the International Association of Leather 

 Trades Chemists, and comparing a specified dilution with the variation allowed by 

 the official method. Samples of hemlock liquor acidified by the addition of 0.15 

 per cent of acetic acid were also sent out for the purpose of testing methods for 

 determining acidity. 



Reports were received from 12 analysts. The results favored the use of the single- 

 filter paper, confirming the work of the previous referee. The evidence relating to 

 the correction of the tannin absorbed by the filter paper was not conclusive. Favor- 

 able results were obtained by diluting 1.6 gm. of the chestnut extract to 100 cc. 

 and 0.6 gm. of the quebracho extract to 100 cc. and determining solids by the official 

 method. The referee suggested that further exi>eriments with varying quantities of 

 extract be made for the purpose of comparing the total solids and assumed tannin 

 content as bases for dilution. The acidity of the hemlock liquor averaged 0.1668 per 

 cent by the provisional method and 0.1368 per cent by the animal charcoal method 

 tested by the referee last year. The apparent loss of acid in the charcoal method 

 was considered worthy of further study. Changes recommended by the referee in 

 the official method were aimed to prevent the loss from evaporation during the 

 weighing and filtering. 



INSECTICIDES AND FUNGICIDES. 



The referee reported considerable cooperative work, and made a 

 number of recommendations concerning the adoption of methods and 

 regarding work for next 3'ear. Method I for the determination of 

 total arsenious oxid in Paris green as given in Circidar 10 of the 

 Bureau of Chemistry was adopted as an official method. The sugges- 

 tions of the referee for future work were in the main approved. The 

 general discussion relating to the determination of nicotin indicated a 

 desire for an improved method. The subject of disinfectants was 

 assigned to the next referee for investigation. 



Report of referee, J. K. Haywood. — Further tests of old methods modified in 

 some cases and of new methods were made by several analysts in collaboration with 

 the referee. Reports were received from 8 analysts on Paris green, 8 on London 

 purjile, 4 on copper carbonate, 4 on potassium cyanid, 3 on soda lye, 2 on tobacco 

 extract, and 3 on formalin. The analytical data with the comments of the analysts 

 were reported in full. 



The referee recommended that the following methods, given in Circular 10 of the 

 Bureau of Chemistry and reported upon by the referee last year, be adopted as offi- 



