360 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



examination of the stains for identity, purity, and color strength 

 is made. An improved method for the purification of tolidine was 

 worked out. A process for the purification of benzidine also has 

 been developed. A critical study is being made of the sulfonation of 

 hydrocarbons, both by the old batch processes and by the con- 

 tinuous vapor phase process developed in this work. A paper giv- 

 ing the results of work on the sulfonation of cymene is in course of 

 publication. Work was done on sulfonated indigotine, on dyes de- 

 rived from cymene, on metallic salts of direct dyes, on the absorption 

 curves of the permitted dyes, and on water of crystallization in 

 dj^es. 



During the year 510,586 pounds of coal-tar colors were certified 

 as suitable for use as food colors. Manufacturers of food products 

 are recognizing more and more the value of certified colors, and the 

 number of firms manufacturing such colors is steadily increasing, as 

 is also the quantity of color offered for certification. 



During the year 12 articles giving the results of the work in the 

 color investigation laboratory have been published and 5 public- 

 service patents have been granted on processes developed. 



FURFURAL EXPERIMENTS. 



Investigations on the manufacture of furfural and adhesives from 

 corncobs and other crop wastes have been practically completed. A 

 little further work is necessary on the development of certain uses 

 for furfural, and to complete the preparation of the results for 

 publication. Practical methods for the manufacture of furfural 

 and adhesives from corncobs and other crop wastes at a compara- 

 tively low cost have been developed. Furfural has not been ex- 

 tensively used heretofore in the technical arts, because the cost of 

 production was too great. It can now be manufactured at a cost 

 that indicates that it may be used rather extensively as a substi- 

 tute for formaldehyde in making synthetic phenol resins of the 

 Bakelite type, as a paint and varnish remover, as an intermediate, 

 with amines, in the production of soluble resins for varnishes and 

 lacquers, as a repellent for the blow-fl}^, and as a possible inter- 

 mediate in the production of mucic and pyromucic acids. 



Work on the manufacture of adhesives from corncobs has been 

 previously reported. 



WORK FOR OTHER DEPARTMENTS. 



Under an authorization for collaboration with other departments 

 of the Government desiring chemical investigations, whose heads 

 request the Secretary of Agriculture for such assistance, the Bureau 

 of Chemistry does a great variety and volume of work, ranging 

 from the testing of supplies furnished on contract to see that they 

 comply with specifications to serving as a consulting expert on 

 chemical problems. 



Assistance is given the Post Office Department in developing cases 

 involving the fraudulent use of the mails for the sale of fake medi- 

 cines and appliances falsely claimed to cure diseases. Analyses are 

 made of drugs, cosmetics, depilatories, fat reducers, poisons, nar- 

 cotics, and commodities suspected of containing harmful agents. 

 Assistance is also rendered the Post Office Department in collecting 

 and preparing evidence for court; cases where technical subjects are 



