GASEOUS EMANATIONS. 215 



neighbourhood of the Lake of Laach,* in the crater-like 

 valley of the Wchr and in Western Bohemia, exhalations of 

 carbonic acid gas manifest themselves as the last efforts of 

 volcanic activity in or near the foci of an earlier world. In 

 those earlier periods, when a higher terrestrial temperature 

 existed, and when a great number of fissures still remained 

 unfilled, the processes we have described acted more power- 

 fully, and carbonic acid and hot steam were mixed in larger 

 quantities in the atmosphere, from whence it follows, as 

 Adolph Brongniart has ingeniously shown,f that the primitive 

 vegetable world must have exhibited almost everywhere, and 

 independently of geographical position, the most luxurious 

 abundance and the fullest development of organism. In these 

 constantly warm and damp atmospheric strata, saturated with 

 carbonic acid, vegetation must have attained a degree of vital 

 activity, and derived the superabundance of nutrition necessary 

 to furnish materials for the formation of the beds of lignite 

 (coal), constituting the inexhaustible means on which are based 

 the physical power and prosperity of nations. Such masses are 

 distributed in basins over certain parts of Europe, occurring 

 in large quantities in the British Islands, in Belgium, in 

 France, in the provinces of the Lower Rhine, and in Upper 

 Silesia. At the same primitive period of universal volcanic 

 activity those enormous quantities of carbon must also have 

 escaped from the earth which are contained in limestone 

 rocks, and which, if separated from oxygen and reduced to a 

 solid form, would constitute about the eighth part of the abso- 



* [The Lake of Laach, in the district of the Eifel, is an expanse of 

 water two miles in circumference. The thickness of the vegetation on 

 the sides of its crater-like basin renders it difficult to discover the nature 

 of the subjacent rock, but it is probably composed of black cellular 

 augitic lava. The sides of the crater present numerous loose masses, 

 which appear to have been ejected, and consist of glassy feldspar, ice- 

 spar, sodalite, hauyne, spinellane, and leucite. The resemblance between 

 these products and the masses formerly ejected from Vesuvius is most 

 remarkable. (Daubeney, On Volcanoes, p. 81.) Dr. Hibbert regards 

 the Lake of Laach as formed in the first instance by a crack caused by 

 the cooling of the crust of the earth, which was widened afterwards into 

 a circular cavity by the expansive force of elastic vapours. See History 

 of the Extinct Volcanoes of the Basin of Neuwied, 1832.] TV. 



t Adolph Brongniart, in the Annales des Sciences Naturdles, t. xy. 

 p. 225. 



