There are yet a few other important deductions to be made from the foregoing facts: (1) the same coal basin may, at the same level, contain fragments of coal of very different ages; (2) its contour may have been much modified owing to the ravines made by the water which transported the ancient parts into the lowest regions of the basin; and (3) finally, since the most recent sandstones and schists of the same basin may contain coal which is more ancient, but which is formed from the same species of plants that we find at this more recent level, we must admit that the conversion of the vegetable tissues into coal was relatively rapid, and far from requiring an enormous length of time, as we are generally led to believe. If, then, lignites have not become soft coal, and if the latter has not become anthracite, it is not that 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