^0 Dr. MacCulloch on certain products 



Here the oxygen is completely dissipated, together with the azote, 

 and the greater portion of the hydrogen. Analogous circumstances 

 determine the putrefaction of animal matter, but in this case the play 

 of affinities is so intricate, that a large portion of the carbon is vola- 

 tilized in the gaseous form. By the constant affusion of water 

 however, this process may be so modified, that the greater part of 

 the hydrogen and carbon will be retained, and enter, together with 

 minute portions of other gases, into a new compound resembling fat, 

 which has obtained the name of adipocire. The analogy is strong, 

 and the gradual deoxydation of the wood in this process is visible 

 in the different stages of bituminization. 



Such, as far as observations have yet gone, is our knowledge of 

 this process and of the power of water in producing it. To repeat 

 such an experiment in the laboratory seems impossible, since the 

 necessary element of time must be wanting to complete it. But the 

 action of fire being of shorter duration, and affording us also readier 

 means of imitating Nature in those operations in which she has 

 wrought with the same agent, it is worth our while to consider, if 

 by it we can produce from vegetables the bituminous matters under 

 review. It is not necessary to say how intimately this question is 

 connected with our speculations on the origin of coal, since Sir 

 James Hall's experiments were expressly intended to illustrate this 

 view of the subject. In this, it is related that " coal" was produced 

 from " fir saw dust" by the usual method employed in these ex- 

 periments, and that pieces of wood were changed " to a jet-black 

 and imflammable substance, generally very porous," in some spe- 

 cimens of which " the vegetable fibres were still visible." There 

 is no reason to doubt that the substance produced in these experi- 

 ments, was that black matter which I have described in the first part 

 of this paper, which, however resembling bitumen in colour and 



