(mAl23ere) 
XIV.—On the Constitution and Properties of Picoline, a new Organic Base from 
Coal-Tar. By Tuomas ANDERSON, M.D. 
(Read, 20th April 1846.) 
THe careful study of the products of destructive distillation has enriched 
organic chemistry with an extensive series of results of unexpected interest and 
importance. These results have affected, in no inconsiderable degree, the recent 
progress of the science ; and their influence has been of a twofold character, both 
general and particular, exerted in the former case in the development of some of 
the more remarkable general doctrines of organic chemistry ; in the latter, in the 
important light thrown by their investigation on the constitution of the substances 
from which they are derived, and the facilities they have afforded of following out 
connections, which the examination of the original substance either does not at 
all present to our view, or, at least, indicates only in an imperfect or dubious 
manner. Added to this, we have the remarkable fact of the appearance among 
these products of substances in some cases identical with those occurring in 
organised beings; and in others, presenting analogies of the very closest charac- 
ter with the actual products of vital affinity, which, taken together, afford abun- 
dant reason for pursuing the investigation of substances which have already 
afforded results of so remarkable a character. 
Setting aside altogether those substances, the occurrence of which is so fre- 
quent, that they may be called the general products of destructive distillation, such 
as carbonic acid, light carburetted hydrogen, olefiant gas, acetic acid, &c., it may 
be laid down as a general rule, that each individual compound produced during 
such a process, is formed by the destruction of a limited number of substances 
only, which bear to each other, and to the product, a more or less intimate con- 
nection in constitution or chemical relations. In those instances in which we 
have been enabled to submit to destructive distillation substances of a definite and 
simple constitution, in a state of chemical purity, and where an uniform tempera- 
ture has been preserved, the results have been, for the most part, of an exceedingly 
simple and intelligible character; but in proportion as the atom becomes more 
complex, so also do the products of its decomposition, and the explanation of the 
results is found to be proportionately difficult and uncertain. These difficulties 
and uncertainties are increased in a still higher degree, in the case of a substance 
such as coal, where we have to deal not merely with one complex atom but with 
a congeries of several such, and where the process is performed on the large scale, 
and under a variety of perturbing influences. The distillation of coal is, in fact, 
VOL. XVE-PART It, 21 
