374 
MR. JOHNSTON ON THE CONSTITUTION OF THE RESINS. 
the result of this analysis may be considered to approach very near to the true 
quantity. 
On comparing together the columns 7, 8, 9 and 10, we see that by prolonged 
heating some volatile matter is given off, by which the per centage of carbon is in- 
creased ; and that such is the case, appears more clearly if a portion of the resin after 
prolonged heating at 200° Fahr. be further heated in a close tube 50° to 100° higher. 
In the cooler part of the tube a colourless naphthoid fluid gradually condenses, while the 
resin does not even begin to cohere. It is difficult to pronounce with certainty that the 
resin is actually decomposed at this temperature, though it does seem exceedingly 
probable. And if we consider the coincidence of the analyses 7, 8 and 10, (the results 
of which are nearly identical, and for all of which the several portions of resin were 
heated only to 212° Fahr.,) to indicate a probable constancy of composition at this 
temperature, and that at a higher heat it undergoes decomposition, we should be led 
to adopt a formula containing nine of oxygen as representing the constitution of this 
resin of benzoin in its real normal state. Thus the formula C 40 H 24 0 9 gives 
Carbon 71 -82 
Hydrogen 7' 03 
Oxygen 21*15 
100 
and these numbers so far agree with the results 7, 8, 9 and 10, as to render this for- 
mula exceedingly probable. On the whole, therefore, as the best expression of the 
entire results, I am inclined to consider 
A. That the resin obtained when the benzoin of the shops is boiled with quicklime, 
well washed, as above described, separated by muriatic acid, extracted by alcohol, 
and dried in a thin film at 212° Fahr., is represented very nearly by the formula 
C H O * 
'-'40 11 24 V7 9 • 
B. That when this resin is further heated to incipient fusion, or for a length of 
time at a temperature approaching that at which it melts, it gives off a volatile liquid, 
and acquires the composition represented by the formula C 40 H 2 4 O g . 
4. It has been stated above, that when the compound of the resin of benzoin with 
lime was washed with boiling water, a yellow solution was obtained, which on being 
treated with muriatic acid gave a resinous precipitate in gray flocks. This was col- 
lected, washed, and dried at 212° Fahr. The quantity was very small, only about 
fourteen grains being obtained from 1200 employed in the last experiment. Dissolved 
in alcohol and evaporated in a thin film, it was reddish-brown, and had much the 
appearance of the resin already analysed. Burned in the air it left 0*6 per cent, of ash, 
and after being heated long at 180° Fahr., and afterwards to incipient fusion, when it 
gave off a perceptible quantity of a volatile oil, 
6*87 grs. (6.835 grs. pure resin) gave C = 18‘33, and H = 5*67 grs., or per cent., 
* By referring to p. 371, it will be seen that the results of the fourth analysis agree with this formula also. 
