MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 87 
cess with the requisite accuracy, I think I am justified in inferring from these expe- 
riments, that by the oxidizing agency of persalts of iron rubiafine is changed first into 
rubiacine and then into rnbiacic acid, and that the latter is reconverted by the action 
of reducing agents, such as sulphuretted hydrogen, first into rubiacine and then into 
rubiafine. The presence of rubiacine, however, in the liquor which has been used for 
dveing wfith madder, seems to prove that its direct formation from rubian is possible. 
Ruhiagme . — This substance belongs to the same group of bodies wdiich includes 
rubianine, rubiadine and rubiafine, arid bears a strong resemblance to these sub- 
stances in properties and composition. It scarcely ever appears in well-defined cry- 
stals. When its alcoholic solution is evaporated spontaneously, it is obtained in the 
shape of small lemon-yellow spherical gr.dns, which, when crushed and examined 
under a lens, are found to consist of small crystalline needles grouped round a centre. 
Occasionally it has an orange tinge, but this is probably due to some impurity. 
When heated on platinum foil, it melts to a brownish-red liquid and then burns with 
flame, leaving a large quantity of carbonaceous residue w'hich burns away with diffi- 
culty. When heated in a tube, it gives a small quantity of crystalline sublimate 
mixed with oily drops. When slowly heated between two watch-glasses, it melts to 
a brownish-red mass, but gives no sublimate. It is quite insoluble in boiling water, 
to which it hardly communicates a tinge of colour. It is more easily soluble in 
boiling alcohol than rubianine or even rubiadine, and does not crystallize out on the 
solution cooling, but is left, on ev'aporation of the alcohol, in crystalline masses as 
just described. It is soluble in concentrated sulphuiic acid with a dark reddish- 
brown colour ; the solution, on being heated, disengages sulphurous acid and becomes 
black. Boiling nitric acid dissolves it with a disengagement of nitrous acid to a 
yellow li(]ui(l, while some oily drops rise to the surface. On the solution cooling, a 
quantity of light yellow crystals, possessed of much lustre, are deposited. Whether 
these crystals are a product of decomposition, or whether they are the substance itself 
in a state of puiity, the impurities having been destroyed by the nitric acid, I am 
unable to state. The latter is the more probable view. Rubiagine is soluble in boiling 
acetic acid with a yellow colour, and crystallizes out again, on the solution cooling, 
in small needles. Ammonia turns it red, and on boiling dissolves it with some diffi- 
cultv, forming a blood-red solution, which on evaporation loses its ammonia and 
leaves the substance behind in the shape of small yellow crystals. It dissolves more 
easily in caustic soda, with the same colour. It is precipitated from its alkaline solu- 
tion by acids in lemon-yellow flocks. The ammoniacal solution gives very slight 
precipitates with the chlorides of barium and calcium, the solution remaining red 
w’ith chloride of barium, and becoming crimson with chloride of calcium. It is 
soluble in baryta and lime-water with a blood-red colour, and is reprecipitated by a 
current of carbonic acid. The alcoholic solution gives, on the addition of acetate of 
lead, at first no precipitate, but the colour of the solution becomes dark yellow, and 
after some time, provided the solution be not too dilute, an orange- coloured granular 
