454 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



INSECTICIDES AND FUNGICIDES. 



The composition and method of manufacture of insecticides and 

 fungicides are studied, as well as the effect they have on foliage, with 

 the idea of increasing the elficiency of such products and suggesting 

 methods of avoidmg injury to vegetation. Investigations to dLscover 

 new and improved insecticides are always under way and improved 

 methods of examining various insecticides are studied. Since Jan- 

 uary 1, 1911, when the insecticide act of 1910 went into eflPect, this 

 laboratory has been charged witli the chemical work of examining 

 insecticides and fungicides (other than cattle dips) under said act. 

 It has also been charged with the microscopic examination of various 

 samples of insecticides and fungicides when'such work is necessary. 



During the year 418 samples were examined, requiring approxi- 

 mately 2,800 determinations. The greater number of these samples 

 have been examined at the request of other bureaus of the depart- 

 ment as follows: 



Bureau of Entomology: 



Insecticide and fungicide samples 335 



Miscellaneous samples 12 



Bureau of Plant Industry: 



Insecticide and fungicide samples 7 



Miscellaneous samples 29 



Other bureaus of the Bureau of Chemistry: 



Insecticide and fungicide samples 24 



Miscellaneous samples 11 



In addition to insecticides and fungicides, numerous other products 

 are examined, including materials employed in their preparation; the 

 examination of fruits, foliage, and plants wliich have been treated 

 with insecticides; fruits, hops, and other materials used in the prep- 

 aration of foods wliich may have been affected by insecticides, etc. 



No inconsiderable amount of time has been devoted during the 

 year to methods for the analysis of insecticides. An exhaustive 

 mvestigation has been conducted in regard to the solubility of Paris 

 green and lead arsenate in water, in order to establish a method for 

 the determination of water-soluble arsenic in these materials in the 

 enforcement of the insecticide act of 1910. This investigation has 

 involved 3,500 determinations of arsenic. Studies have also been 

 made on methods for the determination of other constituents in 

 insecticides, notably, arsenic in London purple, lead in lead arsenate, 

 and methods for the analysis of Bordeaux mixture. 



Much time has also been given to the investigation of problems 

 connected with the properties and effects of insecticides and fungi- 

 cides, the basic principles of which are chemical. One investigation 

 of this character relative to the problem of fumigation with hydro- 

 cyanic acid gas has been carried out in collaboration with the Bureau 

 of Entomology and results of considerable economic importance have 

 been obtained. This study was published as Bureau of Entomology 

 Bulletin No. 90, Part III, "Chemistry of Fumigation with Hydro- 

 cyanic Acid Gas." Orchard tests ^^ith numerous arsenical com- 

 pounds and other poisonous materials are being conducted as in the 

 past, iQ order to study the cause of the injuriou.^ effects of such 

 materials on foliage and to discover, if possible, some v.-ay of over- 

 coming the difficulty, or some new compound which m-ay be used 

 effectively as an insecticide on peach and other tender-foliage trees 

 and plants, without causing injury thereto. 



