240 MR HENRY HOW ON CERTAIN SALTS AND 
dryness, at a heat somewhat below 212’, a crystalline residue remained, which was 
evidently not comenic acid. This was kept at the same heat till it ceased to smell 
of hydrochloric acid ; it was then dissolved in water under the boiling point; the 
fluid, on cooling, deposited well-defined, square, prismatic needles of considerable 
size. A portion, dried im vacuo, gave the following results on analysis. 
' 5-625 grains, dried in vacuo, gave 



I. < 10-740 ... carbonic acid, and 
{ 29260) <= , water: 
4-110 grains, dried in vacuo, gave 
II 7865 ... carbonic acid, and 
1-715... water. 
Calculation, 
ee 
: fs Ini 
Carbon, . : 52:07 52°18 52°17 C,, 96 
Hydrogen, A 4:50 4:63 4°34 H, 8 
Oxygen, . 5 a ai 43°49 ON 80 
100-00 100-00 100-00 184 
From which it will be seen that this substance has the composition of an acid 
ether, or true vinic acid, and is represented by the formula 
HO, C, H, O C,, H, O,, 
and I shall presently shew, that the atom of water is capable of being replaced 
by bases. The acid crystallizes, like the corresponding compound of tartaric 
acid, without water. 
Comenovinic acid is readily soluble in hot water, and may be boiled a short 
time without undergoing decomposition; but if long kept at this temperature, 
comenic acid is reproduced. It is extremely soluble in alcohol. It commences 
to volatilize, when kept in the dry state, at 212°; it fuses at 275° Fahr. into a 
transparent brownish liquid, which becomes, on cooling, a crystalline striated 
mass. When kept at about its fusing point, it sublimes, unaltered in composi- 
tion, in brilliant, long, flattened prisms, of great beauty; the second analysis above 
given is that of the sublimed product. It gives a strongly acid reaction with test- 
papers ; its aqueous solution readily coagulates the white of eggs; it imparts to 
persalts of iron a deep red colour. 
Though of so stable a nature per se, this substance rapidly decomposes in 
contact with fixed bases; so that I have been unable to obtain any of its salts in 
the dry state. All those I have attempted to prepare gave, upon analysis, results 
closely agreeing with the composition of salts of comenic acid, with which their 
general properties were also identical, notwithstanding that I carefully avoided 
application of heat. 
I obtained a salt of ammonia by passing the dry gas into a solution of the acid 
in absolute alcohol. Under these circumstances a precipitate soon forms, in small 
silky tufts of a yellow colour. They preserve their silky appearance on being 

a 

