ON THE RESINS. 
49 
cured was rather a crystalline mass than distinct crystals. 
This resin, he also states, crystallises with much more diffi- 
culty than that of copaiba. 
Its solution in alcohol reddens litmus paper, and possesses 
all the properties of an acid, as it forms saline combinations 
with inorganic bases. 0.538 grammes of the crystallised resin, 
gave by decomposition with the oxide of copper, 0.481 
grammes of water, and 1.540 grammes of carbonic acid; its 
composition is, therefore: 
Carbon 79.15 
Hydrogen 9.93 
Oxygen 10.92 
100.00. 
From these, and a series of experiments similar to those in- 
stituted on the resin of copaiba, it results, not only that the 
crystallisable resin of colophane has the same composition as 
the resin of copaiba, but also that both, considered as acids, 
have the same capacity of saturation. There is, in fact, the 
same relation between them, as between tartaric and paratar- 
taric acids; but the resemblance is even greater, as both are 
anhydrous, whilst tartaric acid is distinguished from para- 
tartaric in the crystalline state by containing a less portion of 
water of crystallisation. 
The combination of this resin with lead has precisely the 
same composition as that of lead and the resin of copaiba. It 
is in the form of a white powder, which melts at a low heat 
like a resin. 
Uncrystallisable Resin of Colophane. — Unverdorben has 
called this Pinic acid, and, as before stated, Berzelius has de- 
signated it as Resin a of turpentine. Although it cannot be 
obtained in a crystalline form, M. Rose subjected it to some 
experiments, more to ascertain its capacity for saturation, than 
to determine its composition. 
Its alcoholic solution presented precisely the same pheno- 
mena as those with the crystalline resin. Its combination 
with lead is insoluble in alcohol; it is prepared in the same 
VOL. II. — no. i. 7 
