Colouring Matter of Rottlera tinctoria. 297 



came into my hands, was a perfectly uniform, dark brick- dust 

 coloured granular powder, perfectly dry, and resembling a very 

 fine red sand. It has a slight taste, and a peculiar, though faint, 

 aromatic odour. It repels water, and is not easily moistened 

 by it, requiring to be shaken with it for some time, and is so 

 sparingly soluble, that even after boiling with it, water ac- 

 quires only a pale yellowish tint ; but the addition of an alka- 

 line carbonate, or, still better, of a caustic alkali, causes the 

 fluid to assume a fine red colour. When boiled with alcohol, 

 the greater part of it dissolves, forming a dark-red solution, 

 and if this be filtered hot from the insoluble matter, it depo- 

 sits, on cooling, a pale flocky matter, which is sometimes so 

 abundant that the fluid is completely filled by it, while a dark 

 red resin remains in solution, and may be obtained by evapora- 

 tion as an amorphous mass. The case is different if ether be 

 employed as the solvent ; a fine red solution is then obtained, 

 which gives no flocks on cooling, but on sufficient concentration, 

 and standing for a couple of days, solidifies into a mass of 

 granular crystals, to which I give the name of Rottlerine. 



By repeated digestion with hot alcohol, the whole of the 

 colouring matters are dissolved, and a pale whitish matter, con- 

 sisting of cellulose and albuminous compounds, is left. A proxi- 

 mate analysis, in which the proportion of albuminous matters 

 was ascertained by a determination of nitrogen, showed the 

 composition of the powder to be 



Water, 



3-49 



Resinous colouring matters 



78-19 



Albuminous matters, 



7'34 



Cellulose, &c, 



714 



Ash, . 



3-84 



100-00 



In addition to these substances it contains also a small 

 quantity of a volatile oil, and apparently, also, of a volatile 

 colouring matter ; for the alcohol which has been boiled with 

 it, after being separated by distillation, retains the smell of 

 the Rottlera, and has a decided yellow colour. 



Rottlerine. — If the colouring matter be boiled with ether, 

 and the filtered fluid evaporated to dryness, it leaves only, an 



