io 7 



some curious substances called phthaleines, some of which are 

 dye-stuffs. One of these, called fluoresceine, is a very curious 

 body, which, when dissolved in hartshorn, shows a splendid 

 green fluorescence. The lecturer concluded his sketch of arti- 

 ficial colours by mentioning that indigo had lately been obtained 

 artificially by Professor Baeyer, and that attempts were being 

 made in Germany to prepare it commercially. He believed 

 that the culture of indigo will soon be a thing of the past. 



