TANNING MATTER, &C^ 91 



T\hich, sulphuric acid has probably been the principal 



agent, and that by means of this acid, the oils of the dif- &c.^on an^artf- 



ferent species of wood have been, converted into bitumen, fidal substance 



and a coaly substance has been formed. having thecha- 



^ ^ -^ . racters of tan* 



The third opinion is tliat of Arduino, *^ who conceives ning matter. 



coal to be entirely of marine formation, and to have ori- 

 ginated from the fat and unctious mattei: of the numerous 

 tribes of animals that inhabit the ocean.. 



And the fourth is Mr. KmwAx's opinion, who consi- 

 ders coal and bitumen to have been derived from the pri- ' 

 mordial chaotic fluid*. 



The limits of this Paper will not permit me to enter 

 into the Tarious arguments and facts which have been ad- 

 duced in the support of these different opinio^s; but the 

 second, or that which regards the vegetable substances as 

 the principal origin of coal, seems by much the most pro- 

 bable, because it is corroborated by the greatiir num'ber 

 of geological facts, as well as by many experiraenti^l re- 

 sults. Most of the former have however been, stated iu 

 different works, and I shall therefore only notice a few ^ 



of the latter which have occurred in the course of my 

 experiments. 



The observations of Dr. Correa de Serra on the 

 wood of the submarine forest at Sutton, on the coast of 

 Lincolnshire, together with similar accounts which have 

 been published in the Philosophical Transactions and 

 other works, demonstrate in the most satisfactory man- 

 ner, that whether vegetables are totally or partially 

 buried under the waves or under the earth, they are not 

 merely by such means converted even into, the most im, 

 perfect sort of coal+. Some process therefore indepeiidl- 



mt 



* Geological Essays, p. 327, 



■f In my Paper, " 0/t the Change of somi of the proximate PrlncipUt 

 " of Vegetables into Bitumen^' I have quoted the remarks of Berg- 

 man, Von Troil, and others, on the compressed state of the 

 trunks of the trees which have been converted into surturbrand9 

 Bovcy coal, and similar substances. The same observation has 

 been also n^de by Dr. Correa de Serra respecting the timber of 

 the submarine forest at Sutton ; and this is the more remarkable, as 

 the submerge^ vegetables at Sutton dp not exhibit any appearance 

 of carbonization. 



