Dr. Schunck on Rubian and its Products of Decomposition. 357 



cess is repeated with fresh quantities of water until no more 

 flocks are carried away by it. The resinous mass at the bot- 

 tom now consists principally of rubiretine. It may be purified 

 by dissolving in cold alcohol, which leaves behind a quantity 

 of verantine. The brownish-yellow flocks consist chiefly of 

 verantine and rubianine ; they are treated with boiling water, in 

 which the rubianine dissolves, and from which it is again de- 

 posited, on filtering the water boiling hot and allowing to cool, 

 in orange- coloured flocks. The process is repeated until the 

 water dissolves nothing more. The orange-coloured flocks of 

 rubianine are collected on a filter and dissolved in boiling alcohol, 

 out of which the rubianine crystallizes on cooling in yellow 

 needles. The mother-liquor is somewhat darker than a mere 

 solution of rubianine would be. It contains a little alizarine 

 and rubiretine, which may be separated by means of acetate of 

 alumina, as before described. The verantine which is left behind 

 by the boding water is mixed with the other portions obtained 

 from the lead and copper compounds, and the whole is dissolved 

 in a small quantity of boiling alcohol, out of which the verantine 

 is deposited on cooling as a dark reddish-brown or yellowish- 

 brown powder, which may be purified by a second solution in 

 alcohol. 



These substances can, as may be supposed, be obtained 

 without any difference in properties by adding sulphuric or 

 muriatic acid to an extract of madder made with boiling water, 

 boiling the liquid, and treating the dark green precipitate 

 obtained in the same way as the orange-coloured flocks, from 

 the decomposition of rubian. The dark green colour of the 

 precipitate in this case proceeds from the decomposition of 

 chlorogenine by the acid ; the product of decomposition does 

 not however in any way interfere, as it is insoluble in alcohol. 

 It may be remarked, however, that very little rubianine is 

 obtained in this manner, its place being supplied, from a cause 

 which I shall mention hereafter, by rubiacine. 



There still remains in the acid liquid filtered from the orange- 

 coloured flocks, a substance which is an essential product of the 

 action of acids on rubian. This liquid has, as I mentioned 

 before, a light yellow colour. After neutralizing the acid with 

 carbonate of lead it becomes almost colourless, while the car- 

 bonate of lead acquires a pink tinge. After filtration it is found 

 to contain neither sulphuric acid nor lead ; nor does it give any 

 precipitate with neutral 01 basic acetate of lead, nor with 

 alkalies, either before or after neutralization, unless it be boiled 

 with an excess of the latter. This absence of reaction proves 

 that no substance of a basic nature has been formed during the 

 process. The liquid however contains a considerable quantity 



