BUREAU OF CHEMISTRY. 277 



pound of copper and barium with arsenious acid, one of a number of 

 new arsenicals prepared in the course of the bureau's work on the 

 improvement of the methods of manufacturing insecticides and 

 fungicides and on the discovery of new insecticides and fungicides, 

 is most effective in killing insects. 



Investigations have also been made upon the sticking qualities of 

 lead and calcium arsenate upon various types of foliage, particularly 

 that of the potato. 



In cooperation with the Bureau of Entomology, as a part of the 

 boll-Aseevil campaign, studies have been made to determine how much 

 soluble arsenic cotton plants will stand. For the same purpose, some 

 hundreds of analyses of samples of calcium arsenate, destined for use 

 in combating the boll weevil, have been made for the Bureau of En- 

 tomology-, in order that no shipments of calcium arsenate unsuitable 

 for use upon cotton might go into the South. It was deemed ex- 

 tremely important that the quality of the insecticide be carefully 

 guarded in order that no prejudice or failure might arise due to the 

 poor quality of some of the insecticides used. 



For the Bureau of Entomology studies have also been made of the 

 quantities of hydroc3'anic acid that remain in fumigated materials, 

 and for the Bureau of Plant Industry numerous determinations have 

 been made in connection with that ])ureau's studies upon the control 

 of cereal diseases. For the Insecticide and Fungicide Board more 

 than COO samples of insecticides and fungicides, including antisep- 

 tics, have been examined, and, where necessary, bacteriological tests 

 have been made. 



DEHYDRATION OF FRUITS AND VEGETABLES. 



During the season of 1918 many manufacturers of dehydrated 

 products suffered serious losses through insect infestation. The in- 

 sect in practically all cases was found to be the Indian meal moth, 

 Plodia inter'puncteTla. In cooperation with the Bureau of Entomol- 

 ogy, an appropriate investigation was undertaken which made it 

 possible to advise manufacturers how to avoid these losses. The 

 results have been very encouraging, so that during the past season 

 the losses of certain of the manufacturers have been very greatly 

 lessened. 



Investigation has shown quite conclusively that vegetables com- 

 mercially dehydrated without blanching or other pre-treatment de- 

 teriorate upon storage. As a result of the l)ureau's propaganda 

 during the past season, the major ]")ortion of the vegetables dehy- 

 drated have been processed and will therefore hold up much better 

 when placed on the market. Many plant managers are not as vet 

 adept m the practice of blanching, and much investigation is needed 

 to determine the proper methods for blanching each product. Manu- 

 facturers have been })laced on the proper road for the production of 

 products of quality. 



Much Avork has been done upon the dehydration of fruits with a 

 view to reducing or eliminating preliminary sulphuring. At the 

 present time some apples are being produced without any sulphuring 

 whatever, while a large volume of fruit is being dehydrated with 

 but ver}' little sulphuring. Some of these products are being mar- 



