222 ANNUAL REPOKTS OF DEPAETMENT OP AGEIC ULTURE. 



INSECTICIDES. ^ 



An investigation, of the decomposition of di-lead arsenate by water, 

 the results of which haA^e been published, has demonstrated how in- 

 jury may take place when treated foliage is subjected to the frequent 

 action of light rains, fog, and dew. In cooperation, with the Bureau 

 of Entomology, the action of pure arsenious oxid, arsenic oxid, di- 

 lead and basic lead arsenate, and calcium arsenate have been tested 

 on various insects. A number of new calcium arsenates have been 

 prepared and their chemical and physical properties investigated. 

 Methods for preparing the two most promising — tri-calcium arsenate 

 and calcium meta-arsenate — on a manufacturing scale have been de- 

 veloped, and a patent covering methods for the commercial prep- 

 aration of tri-calcium arsenate has been obtained. The results of 

 an investigation to determine whether fruits sprayed with Bor- 

 deaux mixture may retain enough copper to be objectionable are in 

 process of preparation. A similar study has been made upon the 

 retention of hydrocyanic acid in foodstuffs that have been treated 

 with this gas for the purpose of destroying insects. The work on 

 the poisoning of bees by sprays is to be published by the Bureau of 

 Entomology. The efforts to modify the formula for Bordeaux 

 mixture have progressed to such a point that it is possible to say 

 that in all probability a formula which will contain much less copper 

 than the present formula can be used for potatoes. The results ob- 

 tained in the study of the adhering qualities of various copper and 

 sulphur fungicides are to be published by the Bureau of Plant 

 Industry. A report upon plants used as insecticides is in press. 



ANALYTICAL METHODS. 



There have been published methods for the separation of aluminum 

 from iron by means of ether; for the preparation of heavy leathers 

 for analysis ; for measuring the absorption of paper ; for the estima- 

 tion of anthraquinone ; for the detection of added color in butter and 

 oleomargarine; for the determination of arsenates in insecticides by 

 potassium iodate; for the estimation of fat in condensed milk and 

 milk powders ; for the detection of added water in milk by means of 

 a simplified molecular concentration constant; for the analysis of 

 acetylsalicylic acid and adulterants ; and for the determination of the 

 volatile oil content of citrus fruits. 



There are in press papers upon the estimation of theobromin; of 

 loosely-bound nitrogen as ammonia in eggs; of copper in insecti- 

 cides ; of copper and zinc in gelatin ; and of vanillin and coumarin in 

 factitious vanilla extracts. There are also in process of publication 

 papers upon the evaluation of hexamcthylene-tetramine tablets; 

 upon the gravimetric and volumetric determination of zinc precipi- 

 tated as zinc mercury thio-cyanate; upon the identification and deter- 

 mination of potassium guaiacol sulphonate; upon the separation 

 and quantitative determination of the lower alkylamines in the pres- 

 ence of ammonia ; and upon the application of the cryoscopic method 

 for determining added water in milk. 



Investigations have been completed upon the determination of 

 acetic acid, methyl alcohol, and acetone in pyroligneous acid; upon 

 tiie limits of sensitiveness of the United States Pharmacopoeia method 



