
XXIV.— On certain Products of Decomposition of the Fixed Oils in contact with Sul- 
phur. By Tuomas ANDERSON, Esq. M.D., F.R.S.E., Lecturer on Chemistry, 
Edinburgh. 
(Read 19th April 1847.) 
- 
Numerous researches have established as a general rule that the products 
of the decomposition of organic substances vary with the circumstances of the 
experiment, and the nature of the agents under the influence of which it is per- 
formed. If, for instance, we examine the action of heat alone, we find it caus- 
‘ing a set of decompositions specially characterised by the evolution of carbonic 
acid, formed by the union of part of the carbon of the substance with the whole 
or part of its oxygen; and this action is rendered more definite, and the number 
of the products circumscribed by all circumstances facilitating the formation of 
carbonic acid, such as the presence of a base, which will even cause its evolution 
when heat alone is incapable of producing decomposition. Acids, on the other 
hand, have a precisely opposite effect, they, in some instances, altogether prevent 
the formation of carbonic acid, and cause the oxygen to exert its action on the 
hydrogen of the compound, and to eliminate one or more atoms of water which 
do not generally exist ready formed in it. 
In these particular instances decomposition takes place at the expense of the 
constituent atoms of the compounds themselves, the extraneous substances serv- 
ing merely as disponents to the oxidation, in the one case of part of their carbon, 
in the other of their hydrogen; but there is another class of agents which, besides 
eliminating one or more substances, are capable at the same time of entering into 
union with the residual atoms, and forming a new derivative of the original com- 
pound. The best investigated of this class of agents are chlorine, bromine, nitric 
acid, and ammonia, the three former of which exert their action on the hydrogen, 
the latter on the oxygen of the substance, and form compounds the complete in- 
vestigation of which is important, not merely in a purely chemical point of view, 
but also from the light which they seem likely to throw on the general question 
of the atomistic constitution of matter. In fact, the great object of the researches 
of organic chemistry at the present moment is that of developing the relations 
which the individual atoms bear to the molecules of their compound, by a know- 
ledge of which we hope eventually to arrive at some definite conclusions with re- 
gard to the mode in which the elementary atoms are grouped together in a com- 
plex molecule. Almost all the scanty information which we possess on this sub- 
ject has been derived from investigating the products of the action of different 
agents upon organic substances; and it is sufficiently obvious, that the more va- 
ried the circumstances, and numerous the points of view under which these re- 
VOL. XVI. PART III. 4Z 
