BUREAU OF CHEMISTRY. 231 



COLOR INVESTIGATIONS. 



The general plan of tlie color investigations which have been in 

 progress in the bureau for but a few years was first fully discussed in 

 the Report of the Chemist last year. This year it is possible to report 

 specific results. 



Work upon photosensitizing dyes was begun at the instigation of 

 the War Department. The three important sensitizing dyes, pina- 

 cyanoh pinaverdol, and dicyanin, have been prepared and made avail- 

 able. Preparations of these dyes have been distributed to those re- 

 quiring them, including photographic plate manufacturers and astro- 

 physicists, who have reported them satisfactory. A new dye showing 

 absorption further in the infra-red part of the spectrum than any 

 other known dye has been prepared. It may prove of great value to 

 physicists. New processes for the manufacture of these photosensi- 

 tizing dyes have been discovered and patent applications filed. Four 

 papers upon the chemical properties of and the methods for produchig 

 these dyes and their intermediates an^l one upon their crystallographic 

 and optical constants have been published. As it is now possible to 

 establish in the United States this very small but scientifically ex- 

 tremel)^ important branch of tlie dye industry, steps to bring this 

 about are being taken. 



The new method developed in the bureau for the production of 

 phtlialic anhydrid by catalytic air oxidation is in successful commer- 

 cial use, and cooperation was begun with another manufacturer during 

 the year. Certain theoretical laboratory investigations remain to be 

 completed before a final report of the whole investigation can be 

 publivShed. 



From cymene a new photographic developer has been produced 

 and the process published. Studies upon the chlorination of cymene 

 are in progress. A report upon the preparation of 2-chlor-5-G-dinitro- 

 cymene is ready for the printer. 



The sulphonation studies have progressed to such a point that 

 cooperation with the industry upon the sulphonation of benzene has 

 begun. Observations of great interest, especially on the sulphona- 

 tion of naphthalene, are in process of investigation. Reports have 

 been prepared upon " Some Difficultly Soluble Salts of Certain 

 Naphthalene Sulphonic Acids," and upon "A Method for the Quali- 

 tative Determination of Some of the Naphthalene Sulphonic Acids." 



The laboratory and plant studies on the production of isopropyl 

 alcohol and its oxidation to acetone, undertaken for the Bureau of 

 Aircraft Production, have been completed. It seems probable that 

 the process will prove of commercial value. 



Papers have also been presented upon the following subjects: 

 " Some Aspects of the Behavior of Charcoal with Respect to 

 Chlorin;" "A Method for the Purification of Certain Azo Dyes;" 

 and " The Catalysis of Some Vapor Phase Oxidation Reactions." 



The laboratory under construction at Arlington for large-scale or 

 semi-industrial operations, which was loaned to the Nitrate Division 

 of the Bureau of Ordnance during the war, has been released to the 

 Bureau of Cliemistry and should be ready for occupancy during 

 the coming year. 



