1 2 4 VEGETABLE D YES. PART i. 



from carbolic acid and from creosote. A blood-red 

 colour is the direct result "of mixing the muriatic and 

 phenic acids. Aniline, the great source of the coal tar 

 colours, yields also a fine yellow. A vast deal of talent 

 has been employed in the research of colouring dyes both 

 at home and abroad, in which the manufacturers them- 

 selves have shown great scientific knowledge. 



Attempts have been unsuccessfully made to obtain a 

 green dye from chlorophyll, the green colouring matter 

 of plants. The want was for a short time supplied by 

 Lo-hao, a Chinese dye, but being unstable it was given up. 

 However the very same substance has been procured 

 from the Rhamnus cathartica (Buckthorn), one of the 

 commonest European trees. M. Charwin of Lyons, who 

 made the discovery, has utilized a waste substance, and 

 rendered it permanent as a dye. It is the only known 

 substance which with proper reagents is capable of 

 producing all the seven colours of the spectrum. 5 



The coal tar colours have nearly superseded those 

 from lichens which incrust rocks, walls and stems of 

 aged trees with brilliant colours, which do not however 

 furnish dyes directly ; they yield a colourless crystalline 

 substance which combines with alkalies to furnish very 

 beautiful dyes ; it is exactly the opposite of rosaniline, 

 which is a base. The Yariolaria dealbata yields lit- 

 mus or orchil, from which the beautiful French purple 

 is made. The Eocella tinctoria and fusiformis give blue 

 and purple, and the pale yellow lichen, Parmelia parco- 

 lerina furnishes a bright yellow dye, which a little 

 ammonia changes to a rich red, inclining to purple. 

 Mauve was first made from orchil, but was not perma- 

 nent. The fine dyes, alizarine blue, Turkey red and 

 garancine, are still much in use. They are derived from 

 madder, the dried roots of the Rubia tinctorum ; the 



5 Lectures by Dr. Grace Calvert on improvement and progress of calico 

 printing and dyeing since 1851. 



