1 2 I NT ROD UC TION. 



there is also an account of his own protracted researches, especially in the 

 coal-districts of Silesia. First of all coal-seams are found which may be 

 directly shown to be composed of the stems of Sigillaria and Lepidoden- 

 dron, for impressions of these plants may be seen in abundance on the 

 bounding surfaces of every layer. Such seams are found in England, but 

 according to Lindley and Hutton l they do not seem to have been often 

 observed there; in Upper Silesia they are quite common. Two instances 

 may be given from the many cited by Goppert. He found thick seams in the 

 southern district of Gleiwitz or Nicolai which show this character completely. 

 These Sigillaria-coals are obtained especially from the Friedrich pit near 

 Zawada. Goppert gives a figure of a piece of coal from the neighbouring 

 Leopold pit which shows numerous impressions of this plant lying across 

 one another in two distinct layers. At Heinrichsfreude near Lendzin the 

 coal consists almost entirely of Stigmarias, and these together with the 

 many small stems of Araucarites which are said to occur close by them 

 would be well worth renewed investigation. At Zawada, moreover, between 

 the Sigillaria-seams were observed smaller layers consisting exclusively of 

 leaves, which Goppert says are the leaves of Sigillaria. At Dombrowa 

 and Myslowitz flattened stems of coniferous structure were found plentifully 

 in the seams, and similar stems at Radnitz in Bohemia. Impressions of 

 ferns also are sometimes though rarely found ; I have seen them myself 

 from the coal (Plattelkohle 2 ) of Niirschau in Bohemia. A further series of 

 examples is supplied by Grand' Eury 3 from the coal-mines of Central 

 France. In Avaize the coal consists of Psaroniae, Calamites and Fern- 

 leaves, in other places almost entirely of leaves of Cordaites. The coal 

 of the Wealden formation of Duingen in Hanover contains frequent inter- 

 mediate layers formed entirely of needles of Conifers (Abietites Linkii 

 of authors), which may be isolated. 



An important part of Goppert's treatise is devoted to proving that the 

 differences, which we find at the present day in pit-coal, may often be 

 traced back to the original composition of the substances obtained from the 

 remains of different plants and converted into coal. Lindley and Hutton 4 

 had already given utterance to the same idea. Goppert derives his proofs 

 from the present condition of the coal itself. Far from consisting of pure 

 carbon, it is possible that it contains no carbon at all in the free state (see 

 Muck 5 ), but only a mixture of hydrocarbons of varying composition and 

 compounds of a variety of substances rich in carbon. The chemical con- 

 stitution determines the practical distinction into caking coal, fritting coal, 



1 Lindley and Hutton (I], vol. ii, Introd. 



[' Mr. F. W. Rudler, of the Museum of Practical Geology, sends the following explanation of 

 this word : ' Plattelkohle also Blattelkohle and Brettelkohle a bituminous schist in Bohemia, 

 like Boghead mineral or like Cannel, and used with ordinary coal in gas-making.'] 



* Grand' Eury (2), p. 146. * Lindley and Hutton (.1). s Muck (1). 



