362 
MR. JOHNSTON ON THE CONSTITUTION OF THE RESINS. 
XVIII. Resin of Galbanum. 
The galbanum resin of commerce dissolves only in small quantity in alcohol, lea- 
ving a large insoluble residue, which is principally composed of gum. Evaporated at 
212° Fahr., the yellow alcoholic solution gives a beautiful brownish-yellow transpa- 
rent resin, fusing readily at that temperature, and emitting the peculiar foetid odour 
of this class of resins. Treated with boiling water, it imparted no colour to it. 
1. After washing with boiling water, and subsequently heating for several days at 
150° Fahr., it left when burned in the air 0*3 per cent, of white ash. Burned with 
oxide of copper, 
A. 7-01 grs. (6*988 grs. pure resin) gave C = 18*69 grs., and H = 5*21 grs. 
B. After further heating, 8*08 grs. (8*055 pure resin) gave C = 2T64, and H 
= 6*22 grs. 
C. And 8*005 grs. (7*98 pure resin) gave C = 2T4, and H = 6-15 grs., or per cent., 
A. 
Carbon 73*99 
B. 
74*33 
C. 
74*15 
Hydrogen 8*29 
8*58 
8*56 
Oxygen 17*82 
17*09 
17*29 
100 
100 
100 
H 28 g^es 
40 Carbon = 
3057*480 
Per cent. 
74*45 
28 Hydrogen = 
349*426 
8*50 
7 Oxygen = 
700*000 
17*15 
4106*906 
100 
2. The close approximation between the theoretical and experimental per centage 
of hydrogen (in B and C) rendering this formula a little suspicious, I evaporated a 
second small quantity of the alcoholic solution of this resin, washed it with boiling 
water, and heated it long in a thin film at 200° Fahr. Of this, on analysis, 
A. 6*486 grs. (6*467 grs. pure resin) gave C = 17*13 grs., and H = 4*892 grs. 
B. 7*333 grs. (7*31 grs. pure resin) gave C = 20*17, and H = 5*72 grs., or percent., 
A. B. 
Carbon 73*27 74*26 
Hydrogen 8*40 8*46 
Oxygen 18*33 17*28 
100 100 
In the first of these analyses there is, from some cause, a considerable deficiency of 
carbon, but the quantity of water, in regard to the accurate determination of which 
great pains were taken, being in both analyses less than is required by the formula 
