214 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



the bureau, through its inspectors, has furnished infoi^mation to that 

 board. 



The bureau has furnished the War Trade Board with experts who 

 have devoted the greater part of their time to assisting that board 

 in considering requests for export and import licenses for chemicals. 



The bureau has assisted the War Department in a number of ways 

 of value in connection with gas warfare. 



TECHNOLOGICAL INVESTIGATIONS. 



DUST EXPLOSIONS. 



In cooperation with The Pennsylvania State College, Department 

 Bulletin 681, " Grain-Dust Explosions: Investigation in the Ex- 

 perimental Attrition Mill at The Pennsylvania State College," was 

 issued. The inflammability of a number of dusts has been determined 

 and an experimental apparatus developed to study the i^gnition by 

 different means of dusts in suspensions of varying densities. The 

 effect of moisture content upon the inflammability of, oat-hull by- 

 products has been investigated. Arrangements have been made with 

 two industrial companies to test the practical value of passing inert 

 gases containing too little oxygen to support combustion into grind- 

 ing machinery as a preventive of explosions. 



Various methods of designing milling equipment, to prevent the 

 accumulation of static electric charges, have been proposed. Many 

 special investigations of explosions and fires in grain mills, elevators, 

 food plants, and storage warehouses were conducted to establish the 

 specific cause and to develop methods of prevention. The numerous 

 fires in the cotton gins of the Southwest last year led to a preliminary 

 investigation which indicates that possibly static electricity may be 

 a causative factor in these disasters. The matter will be pursued 

 further during the coming season. 



COLOR INVESTIGATIONS. 



The guiding principle in this work is that the mechanisms of 

 organic reactions and the laws that govern them should be studied, as 

 well as the practical details of manufacturing processes. For these 

 studies the works chemist has neither leisure nor opportunity. Yet 

 such fundamental knowledge is vital to the progress of the industry. 

 For example, the industry is seriously hampered by the lack of suit- 

 able quantitative methods for the determination of many of the sub- 

 stances with which it deals. It is, therefore, difficult for the works 

 chemist to exercise such exact control over many of the processes as 

 will yield the maximum amount of the desired product. Conse- 

 quently much attention is being given to the development of quanti- 

 tative methods for the determination of the more important sub- 

 stances. Furthermore, chlorination, sulphonation, and oxidation, 

 especially in the vapor phase, and the behavior of catalysts have 

 been made the subject of experimental and theoretical studies which 

 already have yielded what promise to be new methods for the pro- 

 duction of phthalic anhydrid, H-acid. and benzaldehyde and benzoic 

 acid. Of these, the process for making phthalic anhydrid is being 

 developed commercially in a satisfactory mannex\ 



