ANALYSES OF CERTIFIED PERMITTED COLORS. 



209 



Comparison of chemicals entering into the composition of the seven permitted colors and 

 of paranitramlin and betanaphthol. 



With respect to the arsenic content of the finished product, it can 

 be asserted, without any fear whatever of successful contradiction, 

 that the arsenic finds its way into the goods by way of the sulphuric 

 acid which is used in the manufacture of all the permitted colors, as 

 well as in the manufacture of Paranitranilin and Betanaphthol. If 

 arsenic from this source can be kept out of these substances it can 

 also be excluded from the permitted colors. 



Turning now to those ingredients below the parallel lines, the only 

 means of introducing arsenic would be through the hydrochloric acid 

 used, which in turn derives its arsenic from the sulphuric acid used 

 in its manufacture, and since arsenic free-sulphuric acid can be used 

 in the first stages of producing the seven permitted colors and the 

 paranitranilin and betanaphthol, it can also be employed in the manu- 

 facture of the hydrochloric acid used hi the subsequent stages of 

 manufacture of the seven permitted colors. Therefore, it seems 

 unreasonable to permit a higher arsenic content in food colors than 

 in paranitranilin and betanaphthol, which are sold in open com- 

 petition, and which are used for the production of the very cheapest 

 colored cloths, inks, and paints. 



With reference to the content of iron, and other heavy metals, 

 which satisfied the pharmacopoeial tests in the case of paranitranilin 

 and betanaphthol, these materials probably enter the product from 

 the vessels in which the manufacturing operations are performed. 

 The same kind of vessel used in the manufacture of paranitranilin 



97291 Bull. 14712 14 



