MR. JOHNSTON ON THE CONSTITUTION OF THE RESINS. 
37o 
d-1.) 
Carbon 74" 1 1 
Hydrogen 921 
Oxygen 16’68 
H 2u O, gives 
74*22 
8-78 
17-00 
C 40 H 30 0 7 gives 
73'99 
9-07 
16-94 
100 
100 
100 
Whichever of the two formulae in the second and third columns we adopt as the 
representative of the constitution of this resin, we find it very different from that of 
the resin of benzoin in any of the states in which we have hitherto had occasion to 
examine it. If we suppose it to be most nearly represented by C 40 H 30 0 7 , we find 
that by the action of quicklime on the natural resin of benzoin there is separated or 
formed a small portion of a resin containing so much hydrogen as to place it irra- 
tionally in our artificial group, of which C 40 H 32 + a , O y is the expression, and colophony 
the type. Are we, therefore, to infer that the natural resin is a mixture or compound 
of benzoic acid, of a resin C 40 O g , and of another C 40 H 30 0 7 , and that quicklime 
and carbonated alkalies are capable of separating these from each other ; or that by 
these agents the resin is decomposed and transformed into these three compounds, 
which by their means are capable of being obtained from it? This question we shall 
be better able to consider when we have examined the action of other agents on the 
natural resin. 
III. Action of Caustic Potash on Resin of Benzoin. 
When to the solution obtained by digesting the resin of commerce in cold alcohol, 
a concentrated aqueous solution of caustic potash is added, a gray precipitate falls, 
and the supernatant liquid becomes much darker in colour. If the alkali be added 
drop by drop as long as any precipitate appears, the two resinous salts may be sepa- 
rated from each other with considerable accuracy, but if it be added in excess the 
precipitate readily dissolves. In this case the precipitate is again obtained by adding 
a fresh portion of the alcoholic solution of the resin. 
1. The resinous salt thus thrown down was washed with boiling water, in which 
it is nearly insoluble, afterwards re-dissolved in dilute caustic potash, precipitated by 
dilute muriatic acid, which separated the alkali, and then washed with copious affu- 
sions of hot water. The resin was thus obtained in the form of a gray powder, which, 
when dry, dissolved in large quantity and without appreciable residue in hot alcohol 
and ether, but, from both solutions, fell in large quantity on cooling. 
A. Alcohol in small quantity was digested on the whole of the resin, and the solu- 
tion evaporated in a thin film, when it left in the air T03 per cent, of ash. 
• • • 
6 - 43 grs. (6*364 grs. pure resin) gave C = 16"74, and H = 4 - 293 grs. 
B. A second portion of alcohol gave a solution, the resin obtained from which, 
after long heating at 150° Fahr., left 0‘81 per cent, of ash, and 
5-71 grs. (5*66 grs. pure resin) gave C = 14-615, and H = 366 grs. 
