ON THE EXAMINATION OP BALSAM OF COPAIBA. 
30 5 
tor oil, and small quantities of fat oils may even escape de- 
tection. 
In addition to this, a great variety of samples-of balsam 
of copaiba introduced into the market (not all) also produce 
a clouded mixture with pure alcohol, without our being 
able to consider them as impure. Still there is always this 
difference between this effect and that produced by fat oils; 
in this case the mixture, which first becomes rather milky, 
by agitating it, immediately allows the separation of light 
flakes, which at first float on the surface and afterwards are 
deposited at the bottom of the vessel, becoming hard by 
degrees, but still in small quantity, in comparison with the 
balsam examined ; after their separation by filtration, and 
being well washed with alcohol, they remain, under the 
form of a white, dry, and very brittle substance. 
It is insoluble both in hot and cold alcohol, ether, and 
water, but it is readily and completely dissolved in petroli- 
um. It easily melts when heated, and forms a yellowish- 
white resinous mass, which, on the application of more 
heat in a platinum spoon, becomes brown and burns, giv- 
ing out a smell of caoutchouc and a clear flame, and leav- 
ing no residue. This substance, therefore, comports itself 
like a peculiar kind of resin, resembling that portion of 
mastic which is insoluble in alcohol, and it may be consi- 
dered as an accidental principle in the new balsam; because 
all new balsams do not contain it, as I have satisfied myself 
by the examination of different samples brought directly to 
this city from Para and other countries by the New York. 
Out of three of these samples which were equally fluid, two 
had the pale yellow colour of balsam, but the third was 
considerably browner, like dark-coloured Xeres wine. All 
three were perfectly clear and had a strong smell, leaving, 
after boiling, from 40 to 42 per cent, of a dry resin. Mix- 
ed with two parts of a solution of caustic alkali, all three 
specimens, after frequent and strong agitation, separated a 
transparent soap. The brown sample gave, in pure alcohol- 
