362 A Recent Triumph of Synthetical Chemistry. [July, 



but when pure, there is no doubt as to the identity of the artificial 

 and natural dyes, as they are similar in their absorption spectra, 

 their tinctorial powers, their unalterability under the influence of 

 light, and their solubility. 



Whether artificial alizarine will supersede madder to any great 

 extent depends principally on the supply of the raw material, anthra- 

 cene. Dr. Eoscoe says that in an experiment made on a large scale 

 it was found that 100 tons of tar yielded 0*63 ton of anthracene, or 

 1 ton of anthracene could be obtained from the distillation of about 

 2000 tons of coal, not reckoning the quantity of anthracene con- 

 tained in the pitch. But tar distillers have hitherto turned very 

 little attention to this substance, and from some experiments of Mr. 

 Perkin it is probable that some kinds of coal-tar contain considerable 

 quantities of anthracene. Attention being now directed to the sub- 

 ject, all experience tells us that the demand will bring a supply, and 

 already we see signs of this in the advertisement pages of chemical 

 periodicals, where the price of anthracene is regularly quoted along 

 with that of other coal-tar products. Should our anticipations be 

 fulfilled, this discovery, although made by German chemists, cannot 

 fail to be of most benefit to England, the great tar-producing country 

 of the world. Tar distillers will do well to bear this in mind, and 

 examine the influence of various temperatures in distillation, for 

 anthracene is likely to become as important as benzol was a few 

 years ago. 



W. 0. 



