MR. JOHNSTON ON THE CONSTITUTION OF THE RESINS. 
355 
These results, allowing 0*2 per cent, for foreign matter, are equal to 
Heated 48 hours at 180 and 6 
hours at 212 °Fahr. 
Heated long at 212° 
Fahr. 
Heated 12 hours longer 
at 212° Fahr. 
Heated over the lamp 
1 hour at 220° 
Carbon 69*49 
69*90 
70*51 
71*05 
Hydrogen 7*56 
7*55 
7*65 
7*59 
Oxygen 22*95 
22*55 
21*84 
21*36 
100 
100 
100 
100 
The formula C 40 H 26 O 10 , gives 
Per cent. 
40 Carbon = 3057*48 69*75 
26 Hydrogen = 324*47 7’44 
10 Oxygen = 1000*00 22*81 
4381*95 100 
These numbers agree very closely with the result of the second analysis, and do 
not deviate much from the numbers deduced from the first and third analyses. For 
other reasons, besides this accordance, I am inclined to consider the portion employed 
in the second analysis as approaching nearest to the normal state of the resin, and 
have, therefore, no reason at present to doubt that the formula C 40 H 36 O 10 , represents 
very nearly the true constitution of the resin as it exists in the crude assafcetida of 
commerce. 
II. If we compare with each other this formula and that deduced for the resin of 
ammoniac, from the analyses above given, we observe that they differ only in the 
presence, in assafoetida resin, of the elements of one atom of water more than are con- 
tained in the ammoniac resin. Thus 
Assafoetida resin = C 40 H 26 O 10 
Ammoniac resin = C 40 h 25 o 9 
Difference H 4 0 4 
On this coincidence I believe little reliance is to be placed, inasmuch as in neither 
resin is the number of atoms of hydrogen to be considered as certain ; it nevertheless 
suggests the inquiry — can any number of these resins be hydrates of a common 
radical, or does water as such enter into their constitution ? In so far as the direct 
application of heat is concerned, we have already seen*, in the case of opoponax and 
ammoniac resins, that when the temperature is increased so as to cause incipient 
decomposition, the elements are not given off in such proportion as to form water 
only. Water may be one of the products of the decomposition by heat, but if it ex- 
isted as such in the resin, why should other products be always evolved along with it ? 
By comparing the relative atomic proportions of the elements as obtained in the 
four analyses of assafoetida resin above detailed, we shall be satisfied that though the 
* See pp. 351 and 353. 
2 z 2 
