Dr MacCulloch on PeaL ^05 
In stating these results, I have neglected to notice the fixed 
salts and earths which remain after the incineration of the char- 
coal, as they are not essential to the present inquiry. That I 
may not return to this subject, I will here remark, that, in pure 
peat, their nature and proportion will depend on the nature of 
the vegetables from which it has been generated, and that while 
potash, for example, may be found in the peat of submerged 
wood, silica will occur in that produced from gramineous vege- 
tables. But as alluvial earths are frequently mixed with peat, 
the earthy residuum of this substance is generally in greater 
abundance, and often indeed amounts to a considerable quanti- 
ty. Agriculturists may hence judge how little advantage is to 
be derived from peat-ashes as a manure, unless in those cases 
where a considerable quantity of burnt clay has been produced 
by the operation. 
If imperfect peat be now subjected to the same operations, 
the same results are produced, but the proportions of the diffe- 
rent products will be found to differ. In the first stages of the 
decomposition of plants, these differences are not very sensible, 
but they become gradually more so, as the peat subjected to ex- 
amination is more perfect. When perfect peat, not yet entered 
on the stage of bituminization, is thus examined, it will be 
found that the proportion of acid is sensibly diminished, and 
that the more solid new compounds also bear a larger propor- 
tion to the more fluid. There are, in fact, produced more pitch 
and less essential oil, and consequently a larger quantity of char- 
coal, in proportion to the volatile products, is obtained, in the 
distillation of peat, than in that of recent, or undecomposed ve- 
getables. Neglecting the azote in this case, it is therefore appa- 
rent, that the principal chemical change from vegetable matter 
to peat consists in a dissipation of part of the hydrogen and of 
the oxygen. But this is not the only change, as the solubility 
of peat in the various fluids formerly enumerated, proves that 
a new combination has also taken place among some of the elo- 
ments. This soluble matter is analogous to that which is pro- 
duced from the same elements by the action ©f fire, and is in 
both cases a compound of h 3 ?drogen and carbon principally. 
In the process, therefore, of converting vegetable matter into 
peat, the proportions of the original ingredients are not only 
