INSECTICIDE AND FUNGICIDE BOAED. 



349 



The following statistical statement of samples of certain com- 

 monly used spraying materials collected in connection with the en- 

 forcement of the law shows that a material stride has been made each 

 year since the enactment of the law in securing compliance with its 

 provisions : 



Percentage of violations. 



During the course of an investigation to determine how lead 

 arsenates sold in interstate commerce should be labeled and to obtain 

 scientific information relative to the preparation and properties of 

 the various lead arsenates, the chemists working for the board, under 

 the direction of the Bureau of Chemistry, have obtained data which 

 have been offered for publication under the title " The Preparation 

 and Properties of the Arsenate of Lead and Lead Chlor-Arsenate." 

 Several new lead arsenates and lead chlor-arsenates have been pre- 

 pared and their properties studied. The cause of injury to foliage 

 by di-lead arsenate, of which several thousand tons are used annually 

 for spraying purposes, has been found to be due in many cases to 

 its decomposition by salts that occur naturally in the waters which 

 are used for its application. A lead arsenate has been prepared 

 which is soluble under these conditions, and this is now receiving 

 careful field tests by the Bureau of Entomology. 



An electrolytic method has been developed for the separation and 

 determination of zinc, copper, and iron in the presence of arsenic, 

 which has been published in the Journal of Industrial and Engineer- 

 ing Chemistry, January, 1915. A method has been perfected and 

 offered for publication for the determination of arsenic in arsenates 

 and the various insecticidal and fungicidal mixtures containing 

 arsenates by reduction with cuprous chloride and separation of the 

 arsenic by distillation. This work on new methods of analysis was 

 found to be necessary to enable the board's chemists, working under 

 the direction of the Bureau of Chemistry, to examine some of the 

 various samples subject to the provisions of the act. 



Plant pathologists of the board, working under the direction of the 

 Bureau of Plant Industry, have performed a large amount of work 

 to determine the efficacy of fungicides in controlling fungi attaclring 

 plants and the injury to vegetation of certain classes of insecticides 

 and fungicides, which work has been of greatest service in enforcing 

 certain of the provisions of the act. This work involved the making 

 of 1,218 field tests, practically all of which required from one to six 

 months to complete and a number extended over a period of one year. 



