COAL-TAR 53 



ening. Each step in this Aristotelian sorites has, I be- 

 lieve, been experimentally demonstrated, so it seems to 

 lead logically to the conclusion that the increasing 

 use of aniline dyes in food products has added to the 

 energy of the nation. I do not put entire faith in 

 Aristotle's logic until it is confirmed by the calori- 

 meter, so I will not press this argument, but content 

 myself with the safe observation that the coal-tar 

 colours add to popular pleasure, whether or not they 

 increase the public efficiency That they are at least 

 harmless is assured by the United States Department 

 of Agriculture, which analyzes every batch of dyes used 

 in edible products to see that they are not in themselves 

 poisonous and do not contain accidental arsenic. No 

 new dye is added to the allowed list until it has been put 

 through a long series of tests, first on animals, then on 

 man, to see that it is not injurious, even in much larger 

 amounts than are to be used in edibles. 



The use of artificial colours in foodstuffs is increasing 

 rapidly. About 500,000 pounds of dyes are used every 

 year in the United States for colouring foods and drinks. 

 This is some four times greater than the quantity used 

 a few years ago. The favourite colours in this field are 

 the same as those which periodical publishers have as- 

 certained to have the greatest selling value on the cover 

 of a magazine, red and yellow. I leave it to the psychol- 

 ogist to explain this popular preference for the longer 

 wavelengths of the spectrum. The red dyes go largely 

 into frankfurters and the yellow into butter and rival 

 spreads, while all the colours of the rainbow are in de- 

 mand for cake and candy icings and ice cream, and for 



