MR. JOHNSTON ON THE CONSTITUTION OF THE RESINS. 
357 
this is precisely analogous to the change effected as above, by heating the resin of 
assafoetida. With the view of ascertaining how far mere boiling in water would 
produce this change upon assafoetida, I digested a portion of the crude resin of com- 
merce in alcohol, poured the filtered alcoholic solution into a large quantity of boil- 
ing water, and boiled the mixture for an hour. Along with the alcohol a volatile oil 
escaped into the atmosphere, which diffused a powerful odour through the room, and 
which as it came forth from the mouth of the flask affected the eyes, like the fresh 
juice of the onion. After this prolonged boiling the smell nearly disappeared, and 
on cooling the solution, the greater part of the resin subsided slowly in the form of a 
yellow powder, the supernatant liquid remaining turbid for many days. The yellow 
powder dissolved readily, largely, and without residue, in cold alcohol. Evaporated 
and heated to 212° Fahr. for eight hours in a thin film, it gave a resin which at first 
was rapidly coloured by exposure to the light, and by the prolonged heating acquired 
a decidedly reddish brown colour. 
6*5 grs. (6*487 grs. pure resin) gave C = 16*76, and IT = 4*485, or per cent., 
Carbon 71 '43 
Hydrogen 7'68 
Oxygen 20*89 
100 
This result agrees almost exactly with that yielded by the resin after long heating 
over the lamp, and like it agrees with the formula C 40 H 26 0 9 . 
I refrain at present from discussing the question which suggests itself — whether 
we ought to consider the resin thus boiled and heated, or as it is obtained directly 
from the natural product by means of alcohol, to be in its normal state ; or whether 
the presence of a quantity, perhaps variable, of a volatile oil be the only source of 
the different formulae deduced from the analyses of the resin in its two states ? This 
and other questions of a similar character will find their true solution as our investi- 
gation proceeds, and our knowledge of the constitution, mutual relations, and trans- 
formations of the resins becomes more extended. 
The solution of the crude resin of assafoetida in alcohol gives a bulky, white, curdy 
precipitate, with an alcoholic solution of acetate of lead. I have analysed this salt, 
but the result is such as, with other similar results, to indicate the necessity of an ex- 
tended inquiry into the constitution of the salts of this and the other resins. This 
inquiry I propose to enter upon on a future occasion. 
Note . — The odour of this resin suggests the possibility of its containing sulphur as 
a constituent. Boiling nitric acid dissolves the resin completely, with evolution of 
red fumes, but the solution diluted with water and filtered, gave no trace of a preci- 
pitate with chloride of barium. It was burned also by projecting it in small frag- 
ments into a flask containing a fused mixture of chlorate of potash and common salt. 
The mixed salts were afterwards dissolved, but no milkiness was occasioned by chlo- 
ride of barium. 
