Colouring Matter of Rottlera tinctoria. 299 



C 4*460 grains of Rottlerine gave 

 IV. < 11-275 ... carbonic acid, and 

 2 200 ... water. 



Carbon, 

 Hydrogen, 

 Oxygen, . 



i. 



. 69-37 



5-73 



. 24-90 



ii. 

 69-11 

 5-62 



25-27 



in. 

 69-03 



5-59 

 25-38 



IV. 



68-94 



5-26 



25-80 



100-00 100-00 100-00 100-00 



The formula C 22 H 10 6 , is the nearest expression of these 

 results, as is seen by the following comparison of the mean of 

 experiments with the calculation, — 



Mean. Calculation. 



Carbon, . . . 69-112 ^69 -47 ~~~^~~ 13 ^ 

 Hydrogen, . . 5-550 5-26 H 10 10 



Oxygen, . . . 25-333 25-27 6 48 



100-000 100-000 190 



The attempts which I have made to confirm this formula, 

 have not led to any definite results, as Rottlerine is incapable 

 of forming compounds with the metallic oxides, and though it 

 gives a substitution compound with bromine, its properties, as 

 already mentioned, were not sufficiently marked to afford any 

 guarantee of its purity, and it could not be obtained of definite 

 composition. 



Pale Substance obtained by Alcohol. — It has been already 

 mentioned, that the hot alcoholic solution of the a Rottlera de- 

 posits on cooling, a pale flocky substance. These flocks were 

 separated from the dark-red mother liquor, and dissolved in 

 the smallest possible quantity of boiling alcohol, from which 

 they were deposited on cooling, in such abundance, that the 

 fluid became nearly solid. By repeated solution, it was ob- 

 tained of a very pale colour, nearly, but not altogether, white. 

 When collected on a filter, it dries up into masses, resembling 

 the hydrate of alumina, mixed with a small quantity of oxide 

 of iron. It is insoluble in water, readily soluble in hot, spar- 

 ingly in cold alcohol, and scarcely at all in ether. When ex- 

 amined under the microscope, it is found to consist of minute 

 grains, entirely devoid of crystalline structure. It gives no 

 precipitate with lead or silver salts, and does not appear to 

 from compounds with any other substances, but the quantity 



