at time was wanting, but climatic
conditions and environment. Most analyses of specimens of coal have been
made up to the present with fragments so selected as to give a mean
composition of the mass; it is rare that trouble has been taken to select
bits of wood, bark, etc., of the same plant, determined in advance by
means of thin and transparent sections in order to assure the chemist of
the sole origin and of the absolute purity of the coal submitted to
analysis. This void has been partially fitted, and we give in the
following table the results published by Mr. Carnot of analyses made of
different portions of plants previously determined by us:

Carbon Hydrogen Oxygen Nitrogen
1. Calamodendron (5 specimens) 82.95 4.78 11.89 0.48
2. Cordaites (4 specimens) 82.94 4.88 11.84 0.44
3. Lepidodendron (3 specimens) 83.28 4.88 11.45 0.39
4. Psaronius (4 specimens) 81.64 4.80 13.11 0.44
\----v----/
5. Ptychopteris (1 specimen) 80.62 4.85 14.53
6. Megaphyton (1 specimen) 83.37 4.40 12.23

As seen from this table, the elementary composition of the various
specimens is nearly the same, notwithstanding that the selection was made
from among plants that are widely separated in the botanical scale, or
from among very different parts of plants. In fact, with Numbers 1 and 2
the analysis was made solely of the wood, and with No. 3 only of the
prosenchymatous and suberose parts of the bark. Here we remark a slight
increase in carbon, as should be the case. With No. 4 the analysis was of
the roots and the parenchymatous tissue that descends along the stem, and
with No. 6 of the bark and small roots. One will remark here again a
slight increase in the proportion of carbon, as was to be foreseen. The
elementary composition found nearly corresponds with that of the coal
taken from the large Commentry deposit.

Carbon. Hydrogen. Oxygen and
Nitrogen.
Regnault 82.92 5.39 11.78
Mr Carnot 83.21 5.57 11.22

Although the chemical composition is nearly the same, the manner in which
the different species or fragments of vegetables behave under distillation
is quite different.

In fact, according to Mr. Carnot, the plants already cited furnish the
following results on distillation: