152 Report on the Progress of Chemistry. 



The American Chemist, vol. I (new series) contains an ela- 

 borate description of the character and manufacture of these 

 coloring matters. 



About thirty-nine years ago investigations on the coloring 

 matter of madder root were begun : they have been conti- 

 nued up to the present with most interesting and important 

 results. It was found that from the madder root could be 

 obtained the two coloring compounds, purpurine and aliza- 

 rine, to the latter of which the value of the root is chiefly due. 

 The composition of this alazarine being carefully studied, it 

 was found to contain a constituent called anthracine. But 

 anthracine was also found to be a constituent of coal-tar and 

 of mineral pitch, and it became at once a question of the 

 highest interest, whether alizarine might not be constructed 

 by subjecting anthracine to chemical processes. The effort 

 has been crowned with complete success, and artificial ali- 

 zarine, yielding the same colors on cotton goods and 

 declared by competent chemists to be chemically identical 

 with the natural alizarine of the madder root, hasbeen added 

 to the list of valuable coloring materials. According to 

 Dr. Schunck, this is the only essential dye produced of 

 madder, and we are told by Mr. Perkins, that the difficul- 

 ties in the way of manufacturing it are rapidly disappearing, 

 so that the discovery of artificial alazarine can scarcely fail 

 to be equal in importance to that of aniline, the production 

 of which has since expanded into a distinct branch of in- 

 dustry. 



A still later triumph in this same direction is the discovery 

 by M. M. Emmerling and Engler of a process by which 

 indigo has been synthetically made in the laboratory. 



Looking in another direction, we find notice of an inves- 

 tigation by Prof. Henry Wurtz, of New York, of the 

 chemical transformations of silica. Only a preliminary 

 announcement of the experimental researches in this new 

 field has been given, but even this is enough to awaken 



