Abstract
The products of the destructive distillation of caoutchouc have been studied by several chemists. The results at present obtained are, however, quite irreconcileable. Gregory appears to have been the first to direct attention to them, but it is evident that even at the time of writing his 'Handbook of Organic Chemistry’ he was far from considering the true nature of the products as having been ascertained ; for, at p. 346, he says, “When exposed to heat, caoutchouc first melts, and then distils, yielding a mixture of several oily liquids, all of which, as well as pure caoutchouc itself, are carbo-hydrogens. Some of these oils boil at 90°, others at 680° Fahr. ; and at intermediate points I found that one highly rectified oil which boiled at 96°, and had the composition of olefiant gas, when acted on by sulphuric acid, yielded an oil which boiled at 428°, and had the same composition. But most of these oils have the composition of oil of turpentine, C
5
H
4
, or C
10
H
8
. One of them, called
caoutchine
, gives with chlorine an oil, C
10
H
8
+Cl.” Now the above statement contains undoubtedly the best account that could be given in so short a space, of the results that had been obtained up to the time of publication of the work alluded to, but the account is somewhat confused, because the various observers all differ immensely in their results. The expressions C
5
H
4
and C
10
H
8
, as used by Gregory, merely indicate arithmetical relations, and were not to be received as definite formulæ; for, in the first place, C
5
H
4
is, according to our present views, an impossible formulaf, and in the next, caoutchine is C
20
H
16
, not C
10
H
8
. No chemist up to the present time has proved a hydrocarbon of the formula C
10
H
8
( = 4 volumes of vapour) to exist among the products of the distillation of caoutchouc. Such a formula, if proved, would be interesting, because turpentine being the starting-point for Kopp’s empirical formula for boiling-points, any substance having exactly half the number of atoms of carbon and hydrogen, with the same vapour-volume, would serve as the point of departure of numerous speculations upon boiling-points generally. The results of M. Bouchard at are curious, and not easy to understand. He obtains olefiants and eupione, but no bodies of the formula
n
(C
5
H
4
), while Himly obtains bodies of the latter formula and no olefiants. The annexed Table contains the results of the three chemists alluded to.