120 
ON THE BALSAM OF TOLU. 
transformed into the resin js. On dry distillation it yields 
benzoene and benzoic acid. It readily dissolves in alcohol 
and ether. 
Resin /3. C^sH^^W. — Dull yellowish-brown, neither taste 
nor smell, slightly fusible, (above 212° F.) but slightly solu- 
ble in alcohol and ether ; less easily altered than the pre- 
ceding resin. Sulphuric acid colours it violet-red ; caustic 
potash dissolves it with a brown colour. 
The mixture of the two resins, when treated with nitric 
acid, yields gaseous products, consisting of carbonic acid, 
nitrous vapours and deutoxide of nitrogen ; volatile pro- 
ducts, consisting of the hydruret of benzoyle, hydrocyanic 
and a little benzoic acids •, and as a residue, a flaky yellow 
matter, which consists of benzoic acid, intimately combined 
with a yellow resinous colouring matter, which prevents it 
from crystallizing, and accompanies it in all its combina- 
tions, even in that with ether. By the action of heat, 
especially by distillation, the resinous matter is destroyed, 
and the benzoic acid is obtained in a perfectly pure state ; 
the resin furnishes nearly the third of its weight of benzoic 
acid. 
The constitution of the balsam of Tolu seems very 
simple. 
Originally the balsam is formed by the soft resinous 
matter C^^H^^O^, or that which gives rise to it. This resin, 
under the influence of the air, becomes converted into cin- 
namic acid and the resin yg, Csf'H^oO^ -}-02==C^W0* 4- 
CisHioQ^ +H0. We observe, in fact, that in time the 
balsam of Tolu becomes hardened, and contains a larger 
quantity of cinnamic acid. 
The resin C^^H^^O^ can of itself easily yield benzoic acid, 
for CisH^W =Ci^H6 0* 4-2H04-C^ . Perhaps the 
tolene is derived from the carburetted hydrogen ; but it is 
more probable that it becomes converted into a resinous 
