iBSued January 17, 1911. 



United States Department of Agriculture, 



BUREAU OF CHEMISTRY Circular No. 63. 



Superseding Circular 35. 

 H. W. WILEY, Chief of Bureau. 



IDENTIFICATION OF FOOD COLORS. 



A TENTATIVE REPORT ON THE SOLUBILITY AND EXTRACTION 

 OF CERTAIN COLORS, AND THE COLOR REACTIONS OF DYED 

 FIBER AND OF AQUEOUS AND SULPHURIC ACID SOLUTIONS. 



By H. M. LOOMIS, 



Acting chief, Seattle Food and Drug Inspection Laboratory. 



INTRODUCTION. 



The subject of food colors is so extensive, and so little compara- 

 tively has been accomplished in this field, that the reports made have 

 been of necessity of a tentative nature, such for example as the work 

 reported by W. G. Berry, in Circular 25 of this Bureau, in 1905, under 

 the title " Coloring Matters for Food Stuffs and Methods for their 

 Detection." That work, presented by the referee on colors in the 

 Association of Official Agricultural Chemists, was supplemented by 

 a subreport by Mr. Loomis in 1906, issued as Circular 35. This 

 circular has proved of assistance to those doing pioneer work along 

 these lines, having been reprinted in 1908 and 1909 with slight 

 changes. The data presented in the present revision have been 

 modified and extended in accordance with the results of more recent 

 v investigations, and an analytical scheme for the preliminary identi- 

 fication of colors added. The difficulties of this subject and the varia- 

 tions in the colors used preclude any marked degree of finality in 

 such results, but the data are thought to be of special interest and 

 usefulness to food chemists at this time. 



Respectfully, H. W. WILEY, 



Chief of Bureau. 

 Approved : 



JAMES WILSON, 



Secretary of Agriculture. 

 WASHINGTON, D. C., September 10, 1910. 



63261 Cir. 6311 1 



