366 
MR. JOHNSTON ON THE CONSTITUTION OF THE RESINS. 
results, must still be considered as open to suspicion, and be regarded only in the 
light of an approximation. The same remark applies also to the resin A. of elemi, 
though to a less extent, since the resin B. of elemi is less soluble than resin B. of eu- 
phorbium. 
II. Resin B. of Euphorbium. 
This resin has also been analysed by Rose, who obtained 
Carbon 8T47 81 ’76 40 atoms. 
Hydrogen 1T33 1T36 34‘6 atoms. 
Oxygen 7’2 0 6'94 2‘5 atoms*. 
100 
100 
Rose thinks it probable that the resin he analysed was not quite pure, which is 
rendered very probable by his results not agreeing with any formula of which C 40 is a 
member. I have not hitherto obtained it in sufficient quantity to enable me to repeat 
his analysis; when I shall hereafter describe the results of experiments on the relation 
of the resin A. to certain powerful reagents, I hope to have an opportunity of again 
adverting to the constitution of resin B. of euphorbium. 
This resin is considered by Rose to be probably isomeric with the resin B. of 
elemi, but the difference in their physical characters and solubility, supposing no re- 
liance to be placed on the analyses, appear sufficient to render that opinion very 
doubtful. 
XX. Elemi Resin. 
The elemi resin of commerce, like that of euphorbium, consists of two resins, one 
readily soluble in cold alcohol, the other dissolving, to any extent, only in boiling 
alcohol, and falling again in great measure as the liquid cools. The soluble resin has 
the ordinary resinous aspect, is transparent, brittle, brownish yellow, and forms salts 
with the bases ; the sparingly soluble resin falls in colourless crystals, which melt at 
300° + Fahr. into a colourless fluid, becoming when cold a nearly colourless brittle 
mass with a resinous fracture, the solution of which does not precipitate bases. 
The crystallized resin has been analysed by Rose, Hesse, and Marchand, and its 
composition determined with considerable accuracy, and I have thought it necessary 
to submit it to a further examination, chiefly for the purpose of comparing my results 
with those obtained by these distinguished chemists. 
I. Resin A. of Elemi ( readily soluble in cold Alcohol). 
Reduced to powder and digested with cold alcohol, the crude elemi resin gives a 
yellow solution, which by evaporation yields a yellow resin. When nearly free 
from alcohol this resin emits a strong odour of oil of lemons. Treated with boiling 
* Poggendorff’s Annalen, xxxiii. p. 53. 
