ON THE RESINS. 
51 
class, which have been denominated sub-resins by M. Bonastre, 
who was the first to prepare several of them. Their princi- 
pal distinctive character is that of being less soluble in alcohol 
than the other resins and of being partly deposited from their 
solution in boiling alcohol. 
Crystalline Resin of Elemi. — If elemi be treated with cold 
alcohol, and the residue be then dissolved in boiling alcohol, by 
the spontaneous evaporation of the solutions, a certain portion 
of a crystalline resin will be obtained, which can be purified 
by redissolving it in boiling alcohol; the product amounts to 
one-third of the elemi employed. It is in confused crystalline 
masses, the form of which is indeterminate. It is of a pure 
white colour, completely soluble in boiling concentrated alco- 
hol; the solution does not act on litmus paper; it becomes opa- 
lescent on cooling, as a portion of the resin separates; at the 
end of a few days, the separated portions form a flocculent 
crystalline mass. 
The alcoholic solution is not rendered turbid by an alcoholic 
solution of potash, but an aqueous solution of this alkali throws 
down the resin in a white mass. The addition of liquid am- 
monia to the alcoholic solution transforms it into a soft, white 
jelly. The alcoholic solutions of acetate of lead and nitrate of 
silver do not cause any precipitate, nor does this take place if 
a small portion of ammonia be added to a mixture of the solu- 
tions of the resin and of nitrate of silver. 
If this resin be distilled, a brownish balsam first passes over, 
of an agreeable smell, and which reddens litmus paper; if the 
heat be increased, this balsam becomes brown and acquires a 
disagreeable smell, but still reddens litmus paper; no water is 
produced, and only a small portion of charcoal remains in the 
retort. 
h 0.557 grammes of this resin burnt with oxide of copper, 
afforded 0.5685 grammes of water, and 1.677 grammes of car- 
bonic acid. 
II. 0.7635 grammes gave 0.7735 grammes water, and 2.288 
grammes carbonic acid. 
