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XXI. On some of the Products of the Destructive Distillation of Boghead Coal. — Part I. 
By C. Gkeville Williams, Lecturer on Chemistry in the Normal College., Swansea. 
Communicated hy Dr. Sharpe y, Sec. R.S. 
Eeceived November 25, 1856, — Bead January 22, 1857. 
The action of heat on organic substances has been studied under two aspects : in the 
one the relation of the products to the original matter is seen, and we are enabled to 
draw theoretical deductions, in most cases of great simplicity ; in the other, the relation 
is not capable of being traced ; and it would appear, therefore, at a first glance, that the 
study of bodies produced in this manner would be less conducive to the advancement of 
theoretical science. But so far from tliis holding good, it is not too much to assert that 
organic chemistry has been more enriched by products of the second kind than the first. 
The metamorphoses of naphthaline, to which the law of substitution owes so much for 
its development ; the study of aniline, which has so greatly increased om’ knowledge of 
the theory of basic combinations ; the history of the phenyle series and its numerous 
homologues, — are, immense as their influence on the progress of chemistry has been, only 
a few instances of what may be anticipated from the study of products of destructive 
distillation. It is true that their history has been developed, not because of their origin, 
but from their intrinsic interest, yet it cannot be denied that no operation has furnished 
chemistry with products so numerous and diversified in character. It is also unques- 
tionable that no organic type exists unrepresented by bodies of pyrogenous derivation. 
Heat is perhaps the only chemical agent to which we can assign no special function ; 
at one time acting as a powerful incentive to oxidation, at another to reduction ; it is 
generally recognized as the most potent of disruptive forces, yet we sometimes find it 
causing the coalescence and reduphcation of atoms; it is evident, therefore, allowing 
heat to possess these various and apparently antagonistic qualities, that there are few 
organic bodies capable of withstanding high temperatures whose presence among pro- 
ducts of destructive distillation can be looked upon as impossible. The progress of che- 
mical science has moreover shown in repeated instances, that the substances at one time 
regarded as the rarest and most difficultly obtainable, become in a short period those 
with which we are most familiar. The present investigation may be considered a case 
in point, its object being to prove the existence in great quantity in a commercial pro- 
duct, of a class of compounds hitherto only procm’able by processes founded on purely 
theoretical considerations, and requiring considerable care in their prosecution. 
The substance, the distillate from which contains the hydrocarbons forming the sub- 
ject of this communication, is the Torbane-hill mineral or Boghead Coal, worked on a 
