456 MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
tioned, of its crystallizing unchanged out of its alkaline solutions. The baryta com- 
pound, which is obtained by adding chloride of barium to its ammoniacal solution, 
is easily decomposed when it comes to be washed with pure water, the baryta being 
dissolved by the water, a yellow residue of rubianine being left at last. It is not 
capable of separating oxide of lead from acetic acid. In fact it nearly approaches 
the character of a perfectly neutral body, a circumstance which might be a priori 
foreseen from its containing more carbon and less oxygen than rubian itself, the pro- 
perties of which are not far removed from those of an indifferent substance. 
There are three formulae which all of them give for 100 parts, numbers not widely 
differing from those found by experiment, viz. C.j^ Hj; 0 ^ 3 , C 32 Hjg and C 44 H 24 Ogo- 
These formulae require for 100 parts of substance the following amount of consti- 
tuents : — 
028lll7^13- 032 HjgOj 5 . C 44 H 24 Ojo- 
Carbon 58-13 58-00 57-99 
Hydrogen 5-88 5-74 5-47 
Oxygen 35-99 36-26 36-54 
It will be seen that the last formula is that with which the analyses agree best. 
If the first formula be the true one, then the formation of this substance from rubian 
is easily explained. It would then differ by 5 equivs. of water from 2 equivs. of 
rubiretine ; and 1 equiv. of rubianine, 2 equivs. of verantine and 7 equivs. of water 
added together would be equal to 1 equiv. of rubian, as seen by the following equation : 
C28 Oi3+2(C44 H 3 03)+7H0=C5e H 34 O 30 . 
I shall presently show, however, that there is more probability in favour of one of the 
two latter formulae. 
Sugar . — That the substance obtained from the acid liquid after the complete decom- 
position of rubian is a species of sugar, will, I think, be apparent from an enumera- 
tion of its properties. It is always obtained in the form of a transparent yellow syrup, 
which neither crystallizes, however long its solution may be left to stand, nor becomes 
dry, unless heated to 100 ° C. Its taste is sweetish, accompanied by a bitter after- 
taste, like that of burnt sugar. When heated for some time at 100 ° C. it loses a por- 
tion of its water, but remains soft and viscid. On allowing it however to cool, it 
becomes brittle and capable of pulverization. After a few moments’ exposure to the 
air it again begins to attract moisture, which it does as rapidly as chloride of calcium, 
and is soon reconverted into syrup. This is a character which it has, in common 
with ordinary syrup, obtained by boiling a solution of cane-sugar in water. It is 
soluble in alcohol. It is not affected by dilute sulphuric acid, even on boiling; but 
on evaporating a solution to which sulphuric acid has been added, it is decomposed 
in proportion as the acid becomes concentrated, and is changed into a black powder 
like humus. Concentrated sulphuric acid destroys it immediately with disengage- 
ment of sulphurous acid. It is destroyed by nitric acid. By operating on a mode- 
rately large quantity of it, I was enabled to ascertain that the sole product of the 
