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XVIII. On the Constitution of the Resins. Part IF. By James F. W. Johnston, Esq. 
M.A., F.R.S., Professor of Chemistry arid Mineralogy in the University of Durham. 
Received March 16, — Read April 9, 1840. 
IX. Resin of Scammony . 
When the purest scammony of commerce is digested in cold alcohol, a pale yellow 
solution is obtained, which, on evaporation, gives a pale yellow, opake, hard, and 
friable resin. Heated to 300° Fahr. this resin melts, becomes transparent, and emits 
a peculiar odour. By the action of the alcohol the crude scammony is very little 
diminished in bulk. 
A. After heating forty-eight hours at 250° Fahr. the resin obtained from the alco- 
holic solution was still in the state of powder, and 1269 grs. gave C = 2574, and H 
= 9"06 grs. 
B. Heated for twelve hours at a temperature at which it cohered, 1 156 grs. gave 
C = 23-35, and 11= 8-162 grs. 
C. Of a third portion fused and kept in a state of quiet fusion for several hours, 
11-98 grs. gave C = 2375, and H = 8 - 31. 
D. Of a fourth portion fused at 350° Fahr. 9-36 grs. gave C = 18-675, and FI = 6-434 
grains. 
These results are equivalent to 
A. 
Heated 48 hours at 250° 
Fahr. 
B. 
Heated 12 hours at 
260°+. 
c. 
Fused for several 
hours. 
D. 
Fused at 350° Fahr. 
Carbon 56'08 
55-85 
54-82 
55-17 
Hydrogen 7"93 
7-84 
7-70 
7-63 
Oxygen 35 - 99 
36-31 
37-48 
37-20 
100 
100 
100 
100 
I consider the portion B. to represent most nearly the normal state of the resin, and 
this agrees very closely with the formula C 40 FI 33 O 20 , which gives 
Per cent. 
40 Carbon = 3057-500 55'92 
33 Hydrogen = 41F826 7’53 
20 Oxygen = 2000*000 3655 
5469-326 100 
The results C. and D. show that, by further heating, this resin loses both carbon and 
hydrogen, probably from the disengagement of a volatile substance containing less 
