GUIDES IN DETERMINING PURITY. 197 



of that criticism; therefore the rule for cleanliness of product, as just 

 given, has been modified in that respect and to that extent. 



That it was only fan: and reasonable to expect considerable 

 improvement in the cleanliness and purity of food colors was made 

 evident by an examination of two substances sold in the United 

 States in large quantities for the purpose of making a very cheap 

 red coal-tar coloring matter, which is used in many of the cheapest 

 coloring operations, for paints, inks, etc. These substances are 

 paranitranilin and betanaphthol. They were found in the United 

 States market in such a condition of cleanliness and purity that had 

 they been suitable for use in foods no objection could be raised 

 against them on these scores. They complied with the requirements 

 of the United States Pharmacopoeia with respect to freedom from 

 arsenic and all heavy metals, inclusive of iron. The significance of 

 this lies in the fact that all the raw materials entering into the manu- 

 facture of paranitranilin and betanaphthol also enter into the manu- 

 facture of the seven permitted colors of Food Inspection Decision 

 No. 76, and that the only source of arsenic in food colors, and probably 

 the only way in which iron could be introduced into them, is by way 

 of the materials entering into the manufacture of paranitranilin 

 and betanaphthol, and since it has been shown to be commercially 

 possible to keep those bodies out of paranitranilin and betanaphthol, 

 and since there is no occasion whatever for arsenic or iron or other 

 heavy metal being present in any of the materials used in the manu- 

 facture of the seven permitted colors of Food Inspection Decision 

 No. 76, over and above the materials used in the manufacture of para- 

 nitranilin and betanaphthol, there was every reason for believing 

 that the seven permitted colors of Food Inspection Decision No. 76 

 could ultimately be manufactured and marketed in the same degree 

 of cleanliness and purity that paranitranilin and betanaphthol are 

 marketed; in other words, that food colors could be made as clean 

 and as pure as paint colors, a condition not existing in the food-color 

 market of the United States in the summer of 1907. 



The results of the control exercised by the Department of Agricul- 

 ture over the quality of food colors, as compiled in the following 

 section, fully justify such expectations, as well as the aim to make 

 coal-tar colors when used for food purposes of the same high degree 

 of cleanliness and purity as when they are to be used as drugs or as 

 they actually are when used for the manufacture of paints and printer's 

 inks; that is to say, that the coal-tar color used in a colored food 

 should be as clean as the coal-tar color used in making the ink on the 

 label of such colored food, the very reverse of the situation existing 

 prior to the quality control now established. 



