MR. JOHNSTON ON THE CONSTITUTION OP THE RESINS. 
351 
A. 7‘045 grs. gave C — 18*29, and H = 4*79 grs. 
B. 6*76 grs. gave C = 17'62, and H = 4*645 grs. 
These give per cent., 
A. B. 
Carbon 7178 72*07 
Hydrogen 7*55 7’63 
Oxygen 20*67 20*30 
100 100 
The formula C 40 0 9 , gives 
Per cent. 
40 Carbon = 3057'48 7C61 
25 Hydrogen = 311*99 7‘30 
9 Oxygen = 900*00 21*09 
4269*47 100 
which agrees so closely with the experimental results, that we are justified in adopt- 
ing it as the probable formula for the resin. The two portions analysed exhibit a 
slight excess of carbon, which may be attributed to the too prolonged action of the 
heat. This is rendered more probable by the following analysis. 
II. A portion of the resin, dried as above, was heated in a shallow platinum capsule 
over the lamp to a temperature of about 270° Fahr. for some hours, till it had almost 
entirely lost its characteristic odour. No frothing took place, nor were any visible 
fumes given off ; it remained in quiet fusion, gradually assuming a greater consistence, 
and becoming of a darker shade of colour. In this state 
A. 
5*76 grs. gave C 
= 15*2, 
and 
H = 3*91 
grs. 
B. 
6*98 grs. gave C 
K 
CO 
QO 
r-H 
II 
, and 
H = 4*67 
grs. 
A. 
E. 
Carbon 
72*97 
72*77 
Hydrogen 
7* 55 
7*43 
Oxygen 
19*48 
19*80 
100 100 
These results show that by a heat of 270° + this resin is gradually decomposed, 
the volatile matter which flies off containing more oxygen in proportion to the hy- 
drogen than exists in the resin itself, while in some others belonging to the same na- 
tural group, as in the lump dragon’s blood, the contrary is the case. 
Thus deducting 0*23 from the hydrogen of analysis B. for hygrometric moisture, it 
becomes 
Carbon 72*77 40 atoms 
Hydrogen 7*20 24*24 atoms, and loss = 0*76 atoms 
Oxygen 20*03 8*41 atoms, and loss = 0*59 atoms 
100 
