INSECTICIDE AND FUNGICIDE BOARD. 413 



SPECIAL INVESTIGATIONS. 



During the past year and for a year or two previous to this the 

 chemists of the board have made investigations to determine how 

 lead arsenates sold in interstate commerce should be labeled and to 

 obtain scientific information relative to the preparation and proper- 

 ties of the various lead arsenates. Work on this subject completed 

 during the fiscal year ending June 30, 1916, was published in the 

 form of two papers during the fiscal year ending June 30, 1917, viz, 

 " The Preparation and Properties of Lead Chlor Arsenate — Artificial 

 Mimetite," The American Journal of Science (ser. 4), volume 42, 

 page 139, August, 191G, and " The Arsenates of Lead. First Paper," 

 Journal of the American Chemical Society, volume 38, page 2027, 

 October, 1916. 



During the fisca'l year ending June 30, 1917, w^ork was completed 

 on two more papers on this subject, the titles and references to which 

 folloAv : " The Arsenates of Lead. Second Paper," Journal of the 

 American Chemical Society, volume 38, page 2366, November, 1916, 

 and " The Arsenates of Lead. Third Paper, Basic Arsenates," Jour- 

 nal of the American Chemical Society, volume 39, No. 5, page 937, 

 May, 1917. 



Work also was completed on a study of the action of water on di- 

 lead arsenate, and the paper was prepared and accepted for publi- 

 cation in the Journal of the American Chemical Society under the 

 title of " The Action of Water on Dilead Arsenate." 



The investigation started some time ago to discover a chemical 

 method of determining stems in insect powder, establish standards 

 for insect powder, and study the process of manufacture of insect 

 powder and composition of raw materials as well as the finished 

 product, prepared under known conditions, has been completed and 

 will shortly be offered for publication as a bulletin under the title 

 " Insect Powder." 



A paper has been prepared and accepted for publication in the 

 Journal of Agricultural Research under the designation, " The Oc- 

 currence of Manganese in Chrysanthemum Cinerariaefolium." 



An investigation of the various calcium arsenates has been in 

 progress for nearly two years and several new calcium arsenates have 

 been prepared and the projierties of same studied. Information, 

 both of practical and scientific importance, has been obtained which 

 will later be collated and offered for publication. 



Work has been started for the purpose of determining the com- 

 position and methods of preparation of tobacco dust sold on the 

 American market and establishing satisfactory standards for this 

 product. All of the larger firms producing this product have been 

 interviewed and many samples have been collected for chemical in- 

 vestigation and study. The results of this work will be of great 

 service in recognizing adulteration and misbranding of this class 

 of goods. 



Aside from the routine work of testing the efficacy of proprietary 

 insecticides and fungicides, the entomologists and plant pathologists 

 of the board have continued the investigations relative to the practical 

 value of a number of substances in the control of certain insects and 

 diseases, including pyrethrum powders, tobacco powders, and nico- 



