PEAT. 349 



oil are given over ; while ? the bistre itself giving out 

 the same products, the final remains are charcoal, as 

 before ; though, in the last stage, carburetted hydro- 

 gen alone is procured, as, by still urging the first char- 

 coal, the produce is hydrogen, with the usual well- 

 known change in that substance. The chemical reader 

 will understand the nature and causes of what I cannot 

 here afford to detail. In the usual coarse manner of 

 operating, just as in the wasteful practice respecting 

 coal gas, two distillations are going on together; and 

 thus the produce is a mixture of hydrocarburetted gas 

 and carbonic oxyde, while the volatile oil is itself con- 

 verted into gas, so as to escape notice, as it had for- 

 merly escaped discovery. It may indeed be obtained 

 by redistilling the tar, but is then dark and thick ; 

 approximating more nearly to that, as a greater heat 

 is required to separate it, and thus maintaining that 

 exact relation to naphtha which pervades the whole of 

 these compounds as compared to the bitumens. When 

 obtained by a low heat, it is as colourless arid volatile as 

 pure naphtha; under which name I perceive it is now 

 sold for use, as it might have been ever since the dis- 

 tant period at which I published this "discovery;" then 

 also pointing out the use of this " essence of smoke" as 

 a substiute for smoking in the curing of meat. Though' 

 of little moment for my present purpose, I ought also 

 to add,, that a small quantity of ammonia is also ob- 

 tained ; combined, of course, with the acetic acid. 



I need not be more chemically minute respecting 

 an analysis which I only want, here, as a foundation 

 for the enquiry respecting the progress from peat to 

 coal. Sufficient accuracy for this end is attainable, 

 by attending, generally, to the proportions of these 

 several substances in the two cases of peat and the 

 bituminous lignites. Commencing therefore with peat, 



