PLAN OF THE EXPERIMENTS. 



The tables given in this report show the result of experimental 

 work done on various coloring matters. Most of the coal-tar colors 

 used were obtained direct from the manufacturers or agents, to whom 

 acknowledgment is due. The names of these firms and the abbre- 

 viations under which they are designated in the descriptions of the 

 colors in the tables are as follows: 



H. A. Metz & Co., agents for Meister, Lucius & Briining (M. L. B.). 



Berlin Aniline Works (Berlin). 



American Aniline and Extract Company, agents for Brooke, Simpson & Spiller, 



Ltd., London, E. (B. S. S.). 

 Continental Color and Chemical Company, agents for F. Bayer & Co. (By.) 



and Badische Anilin- und Soda-Fabrik (Bad.). 

 Cassella Color Company (Cassella). 

 Geisenheimer & Co., agents for K. Oehler (Oehler). 

 Read, Holliday & Sons (R. H.). 

 Schoellkopf, Hartford & Hanna Company (Sch.). 

 W. F. Sykes & Co., agents for St. Denis Dye ^tut'f and Chemical Company 



(St. Denis), and for Coez, Langlois & Company (Coez) or (Sykes). 

 Kalle&Co. (Kalle). 

 Eimer & Amend (E. & A.). 

 George Griibler & Co. (Griibler). 



The revision of Tables I to IV consists chiefly in a rearrangement 

 of the data and a consecutive numbering of the colors in a m inner 

 which permits of ready reference from one table to another and ren- 

 ders the information more readily accessible. While these tables do 

 not by any means include all food colors, the greater part of those 

 usually employed will be found. A thorough examination has been 

 made of the colors used in this investigation and some important 

 corrections have been made. The tables have also been extended 

 somewhat and an analytical scheme for the preliminary identification 

 of colors has been added (see page 62) . 



As has been pointed out by several workers on this subject, any 

 scheme for the identification of colors in foodstuffs and allied sub- 

 stances is necessarily subject to constant revision on account of the 

 vast number of colors, both natural and synthetic, which are already 

 on the market, and the number of which is constantly being increased. 

 However, in the author's experience, the number of colors used for 

 that purpose commercially is quite limited, as the matter of cost and 

 availability excludes many of the natural colors and the nature of 

 each food product excludes dyes other than those of a certain color or 

 chemical nature. 



It is very essential for the identification of a coal-tar color, or any 

 other coloring matter in foods, to obtain the color in as pure a state as 

 possible. All colors used in the preparation of these tables were 



[Cir. 63] 



