ON THE RESINS. 
47 
If the resin combines without decomposition with the oxide 
of silver, it contains in this combination four times as much 
oxygen as the oxide; for the quantities of oxide of silver indi- 
cated above, contain on an average 1.9 oxygen, whilst the 
resin contains 715. A combination of resin and oxide of 
silver, in which the proportions of oxygen are in the propor- 
tion of 4 to 1, would, according to calculation, be formed of 
28.42 oxide of silver, and 71.58 resin; the result of the first 
experiment is in accordance with this; in the two others,' a 
little resin had been evidently precipitated with the combina- 
tion. 
0. 3575 gram, of this, belonging to the quantity employed 
in the third experiment, and consequently containing 0.2575 
of resin, gave, on combustion with oxide of copper, 0.243 
gram, of water, and 0.757 gram, of carbonic acid, correspond- 
ing to 10.40 per 100 of hydrogen, and 80.65 per 100 of car- 
bon. It results, therefore, that the resin combines with the 
oxide of silver, without decomposition. 
An alcoholic solution of acetate of lead poured into an alco- 
holic solution of resin of copaiba, caused an abundant precipi- 
tate of a combination of resin of capaiba and oxide of lead; 
this precipitate was less crystalline than that with the oxide of 
silver. When heated in a dry state, it melted like a resin. 
To analyze it, M. Rose calcined it carefully in the open air, 
and obtained for residue a mixture of oxide of lead and metal- 
lic lead; the oxide was afterwards dissolved in diluted acetic 
acid. 
1. 0.455 gram, of the combination gave 0.074 gram, oxide 
of lead, and 0.048 gram. lead. 
2. 0.5755 gram, of the combination gave 0.0415 gram, 
oxide of lead, and 0.108 gram. lead. 
This combination is therefore composed of: 
1st 
Oxide of lead, 27.63 
Resin, 72.37 
2d. 
27.42 
72.58 
In this combination also, the resin contains four times as 
