1 o I NT ROD UCTION. 



as was done by the earlier writers. It was by different ways that men at 

 length arrived at the conviction that they are all of organic origin, and that 

 they consist of fragments of plants in a greatly altered condition, placed in 

 layers one above another, and firmly caked together with the help of a fine 

 silt or detritus. 



One way was the examination of thia sections of coal under the micro- 

 scopea method first adopted by Witham l in 1833, and recently employed 

 by Reinsch 2 , and by Fischer and Riist 3 . We are still looking for the 

 results of similar investigations commenced by Williamson some time ago. 

 In this way we have learnt that anthracite in the mass is almost absolutely 

 homogeneous and non-transparent. A few evident traces of the tissue of 

 the higher plants were detected in anthracites, together with a great number 

 of small spaces or areas occupied by a transparent orange-yellow or garnet- 

 red substance, which might certainly be compared to cells filled with 

 secretion, though very dissimilar in shape. The substance of these areas 

 is said by Fischer and Riist to consist of resin or some hydrocarbon ; it burns 

 readily, and is partially soluble in carbon bisulphide or in ether, the dis- 

 solved portion crystallising in needles on evaporation of the solvents. These 

 areas are much more abundant in cannel coal than in anthracite. Boghead 

 coal from Scotland appeared to be almost entirely composed of them. 

 Large quantities of hydrocarbon maybe obtained according to Muck 4 from 

 coals of this description by treating them with ether, and the solution 

 is beautifully fluorescent. Reinsch, who also observed these brown-coloured 

 areas, saw in them the remains of organised structure ; he recognised in the 

 mass of coal, that is, in the small partial layers of the seam, stromata with 

 cavities interspersed, and considers them to be the product of membraneless 

 protoplasm-masses springing from lower organisms. In presence of the 

 botanical investigations which we shall have to notice, we need not go 

 further into these fancies, which must not be taken seriously. 



The probability of our getting sight of organic fragments to any 

 considerable extent on the surface of a section of coal was never very 

 great. It is not surprising therefore that greater success was attained 

 from the first by simply breaking up the coal into very small splinters, 

 and endeavouring to make these transparent by means of petroleum. 

 Link 5 especially, and Goppert also, pursued this method, and the latter 

 demonstrated the presence of the skeletons of single cells and fragments of 

 vessels in coal-ashes. 



But by far the most important method of investigation was that tried 

 by Schmid and Schleiden 7 , who endeavoured to reduce the compactness 

 of the coal by maceration. Their imperfect mode of treatment with 



1 Witham (1). * Reinsch (1). 3 Fischer (1) (Fischer und Riist). 4 Muck (1), p. 48. 



5 Link (1). Goppert (2). 7 Schmid und Schleiden (1). 



