Royal Society. 473 



fact that the extract, if concentrated, hecomes after some time thick 

 and gelatinous ; and that the process of decomposition takes effect 

 chiefl}^ on the rubian is apparent, since the extract, after it has be- 

 come gelatinous, is found to have lost its bitter taste and the greater 

 part of its j^ellow colour. 



In order to prepare the peculiar fermentative substance of madder, 

 which has the power of effecting the decomposition of rubian, it is 

 merely necessary to add to an extract of madder made with cold or 

 tepid water, about an equal volume of alcohol. This causes the 

 separation of a quantity of dark reddish-brown flocks, which are 

 collected on a filter and washed with cold alcohol, until the perco- 

 lating liquid, which is at first strongly coloured, becomes almost 

 colourless. The substance on the filter has the appearance of a 

 dark reddish-brown granular mass, which possesses in an eminent 

 degree the power of decomposing rubian. It is a true ferment, to 

 which the author gives the name oi Erythrozym. If a quantity of it 

 be added to a solution of rubian, and the mixture be left to stand at 

 the ordinary temperature, a complete change is found to have takee 

 place in the course of a few hours. The liquid is converted into a 

 trembling jelly of a light brown colour, which is perfectly tasteless, 

 insoluble in cold water, and so consistent, that if the solution of 

 rubian was tolerably concentrated, the vessel may be turned over 

 without its falling out. During this process none of the usual signs 

 of fermentation are manifested. The liquid remains perfectly neutral, 

 and no gas of any kind is disengaged. On treating the gelatinous 

 mass resulting from the process with cold water, an almost colourless 

 liquid is obtained, which contains the same species of sugar as that 

 formed by the action of acids or alkalies on rubian. The mass left 

 undissolved by the cold water consists partly of the ferment em- 

 jiloyed and partly of the sulistances formed by the decomposition of 

 the rubian. These substances are six in number, of which three 



are bodies previously described, and three are new. They are, 



Ut. Alizarine ; 2nd, Verantine; 3rd, Rubiretine ; 4th, a substance 

 closely resembling rubiacine, which the author calls Rubiafine ; 

 5th, a substance very similar to rubianine and rubiadine, on which he 

 bestows the name of Rnbinrjine ; and 6th, a peculiar fatty substance 

 which he denominates Rubiadipine. 



The three latter bodies, which are products peculiar to this pro- 

 cess of decomposition, have the following properties : — 



Rubiafine is obtained l)y crystallization from alcohol in yellow 

 glittering plates and needles, which are sometimes arranged in star- 

 shaped or plume-shaped masses. It cannot be distinguished by any 

 of its properties from ruljiacine ; its composition is however different. 

 Like the latter it is converted by the action of persalts of iron into 

 rubiacic acid. The author has again submitted rubiacine and rubi- 

 acic acid, together witli some of their compounds, to analysis, and 

 from a comparison of their composition with that of rubiafine, he 

 infers that the formula of tlie latter is €..,oH,3 0,„ that of rubiacine 

 ^-.s J^ii <^>io. that of rul)iacic acid C,,„H,, Oi,; and he inclines to the 

 belief, that by the action of persalts of iron rubiafine first passes into 



