on Structure in the Ashes of Plants. 415 



them, and I had not heard of them." I have myself also been 

 favoured by Mr. Brown with some account of his experiments. 

 He showed me in the ashes of one plant, what I have never 

 seen elsewhere, a very beautiful form of siliceous cellular 

 structure, having the walls of the cells covered with minute 

 siliceous granules ; and in another plant, owing to the pre- 

 sence of some alkaline product, the silica which it contained 

 was readily fused, and Mr. Brown was therefore able, by 

 careful incineration, to procure perfect spherical lenses. 



Having now satisfactorily ascertained that the siliceous or- 

 ganization of recent plants is not destructible even under the 

 blowpipe, it appeared to me to follow, as a natural inference, 

 that the less intense heat of a common fire would not destroy 

 the siliceous organization in the fossil plants of coal. Ac- 

 cordingly, I find in the white ashes of coal all the usual forms 

 of vegetable structure, viz. cellular structure, smooth and 

 spiral fibre, and annular ducts. An engraving of some of 

 these forms accompanied my former paper, and perhaps a 

 still more accurate idea may be given of them if I refer to 

 the late Mr. Slack's drawings of the tissue of plants in the 

 Transactions of the Society of Arts, vol. xlix. plate 6. The 

 elementary organs represented by Mr. Slack possess of course 

 their due admixture of carbonaceous matter, and there can 

 be no doubt that the removal of the carbon, by fire, would 

 be universally supposed, a priori, to be accompanied with the 

 destruction of the tissue. But so far from this being the case, 

 the most delicate markings remain undisturbed, and I can 

 confidently refer to figures 7, 12, 21 b, 23, 26, 27, 28, 30, as 

 most accurate representations of the vegetable forms which 

 occur in the white ashes of coal. 



The vegetable origin of coal, which even at this day is, by 

 some persons, admitted rather than believed*, is thus clearly 

 proved, and from a comparison of the ashes of coal with those 

 of recent plants, some further insight might probably be 

 gained into the nature of fossil vegetables. To mention only 

 one instance, I have already ascertained that the lumps of 

 carbonized matter which occur abundantly in the upper sand- 

 stone near the Spa at Scarborough, are in all probability por- 

 tions of the stem of some arundinaceous or gramineous plant. 

 The structure of the epidermis is precisely similar to that 

 of the oat, consisting of parallel columns set with fine teeth, 

 dove-tailing, as it were, into each other, while the underlying 

 tissue consists of cubical cells, a thin horizontal section ex- 



[• In order, however, to obtain complete ideas of the nature of coal, 

 it will be requisite to compare Mr. Reade's results, as above, with Mr. 

 Hutton's " Observations on Coal," Lond. and Edinb. Phil. Mag., vol. ii. 

 p. 302.— Edit.] 



