MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 417 
rubiadine, and forms with baryta a compound which crystallizes in dark reddish- 
brown needles. I obtained so small a quantity of this substance that I was unable to 
arrive at any positive conclusion as to whether it is identical with rubiadine or not. 
The residue left on evaporation of the alcoholic solution was analysed without any 
attempt being made to purify it, when it was found to have a composition nearly 
approaching that of rubiadine. 
0'2980 grm. gave 07525 carbonic acid and 0‘1450 water, corresponding in 100 
parts to — 
Carbon 68’86 
Hydrogen 5 "40 
Oxygen . 2574 
The formation of this body, as well as that of verantine and rubiretine, from chloro- 
rubian, I am unable to explain in a satisfactory manner. 
If the excess of sulphuric acid, with which the four last bodies have been precipi- 
tated, be neutralized with carbonate of lead, the filtered liquid leaves on evaporation 
a saline mass, w’hich, on being pulverized and treated with warm alcohol, communi- 
cates to the latter a reddish-brown colour. The alcoholic liquid, after being filtered 
from the insoluble matter consisting of sulphate of soda, leaves on evaporation 
crystals of chloride of sodium surrounded by a brown syrup of sugar. 
Action of Chlorine on Chlororuhian . — If finely pounded chlororubian be mixed 
with water, and if, after the mixture has been placed in a large bottle or other suit- 
able vessel, a current of chlorine gas be passed through it, no change is perceptible 
for some time ; but if the bottle be closed, after the space above the liquid has been 
filled with chlorine, the latter is gradually absorbed, the colour of the chlororubian 
becomes paler, and after several days it appears perfectly white. The process is not 
accelerated by the action of sunlight, but frequent agitation of the liquid and pow- 
der with the gas assists it. The white powder into which the chlororubian is changed 
consists of a body to which I will give the name of Perchlororubian. After collect- 
ing it on a filter and washing out the chlorine and acid with water, it is to be dis- 
solved in boiling alcohol, from which it crystallizes on the solution cooling in colour- 
less, transparent, flat, four-sided tables, exhibiting a beautiful iridescence. If it 
should not be quite colourless, it must be redissolved in boiling alcohol, to which a 
little animal charcoal may be added. On filtering boiling hot and allowing to cool, 
the solution then yields perfectly colourless crystals. It may also be obtained directly 
from rubian, by continuing to pass chlorine through a watery solution of the latter, 
until the yellow precipitate produced at first has become white, but by this means it 
is not obtained as pure as from crystallized chlororubian. 
Perchlororubian has the following properties. When heated on platinum it melts 
to a brown liquid, and then burns with a smoky yellow flame edged with green, 
leaving little carbonaceous residue. If slowly and carefully heated it may be entirely 
volatilized, yielding a sublimate of bright micaceous scales. But if it be suddenly 
3 K 2 
