206 



COAL-TAR COLORS USED IN FOOD PRODUCTS. 

 Arsenic content of 86 lots of certified colors. 



1 The certification of these lots was due to an unknown source of error in the analytical method; the 

 analyses made at that time (July, 1909), showed less than 1 part of As2O 3 per 400,000; see also page 204. 



It is therefore somewhat premature to attempt to define rigidly 

 the requirements for composition and purity for colors until a suffi- 

 cient number of analyses is available to permit a hard-and-fast line 

 to be drawn for each item as required for each color. Until that 

 time the decision as to whether or not a certain color shall be cer- 

 tified must rest with the Department of Agriculture. However, 

 the following requirements are tentatively suggested as being com- 

 mercially practicable. It should be clearly understood that the ten- 

 tative requirements here stated are based on the results of actual 

 control, and are not any more searching or numerous than are the 

 requirements for many if not most of the coal-tar dyes or their com- 

 ponent parts in the industrial arts, particularly for the various kinds 

 of paint, varnish, and ink making. While it may be that some of the 

 tentative requirements herein defined necessitate the expenditure of 

 considerable work and time, yet that is also true of some of the 

 commercial requirements. Since manufacturers of cheap paints, 

 varnishes, inks, and the like, find it wise and necessary carefully to 

 control the quality of the coal-tar dyes or their component parts 

 which they use, it can not be less wise or necessary to extend the 

 same kind of quality control to those coal-tar dyes intended and sold 



