158 SPRINGS, RIVERS, CANALS, LAKES, 



savanna on the spot, would be a more obvious mode of accounting 

 for this singular phenomenon ; but, as I shall immediately state, 

 all this part of the island is of recent alluvial formation, and the 

 land all along this coast is daily receiving a considerable accession 

 from the surrounding water. The pitch lake with the circumjacent 

 tract being now on the margin of the sea, must in like manner have 

 had an origin of no very distant date; besides, according to the 

 above representation of Capt. Mallet, and which has been frequeutly 

 corroborated, a fluid bitumen oozes up and rises to the surface of 

 the water on both sides of the island, not where the sea has 

 encroached on and overwhelmed the ready-formed land, but where 

 it is obviously in a very rapid manner depositing and forming a new 

 soil. 



From a consideration of the great hardness, the specific gravity, 

 and the general extern-') characters of the specimens submitted a 

 few years ago to the examination of Mr. Haichett, that gentleman 

 was led to suppose that a considerable part of the aggregate mass 

 at Trinidad was not pure mineral pitch or asphaltum, but rather a 

 porous stone of the argillaceous genus, much impregnated with 

 bitumen. Two specimens of the more compact and earthy sort, 

 analysed by Mr. Hatchett, yielded about 32 and 36 per cent, of 

 pure bitumen : the residuum in the crucible consisted of a spongy, 

 friable and ochracenus stone ; and 1OO parts of it afforded, as far 

 as could be determined by a single trial, of silica 6O, alumina 10, 

 oxide of iron !O, carbonaceous matter by estimation 11 ; not the 

 smallest traces of lime could be discovered ; so that the substance 

 has no similarity to the bituminous limestones which have been 

 noticed in different parts of the world *. I have already remarked, 

 that this mineral production differs considerably in different places. 

 The specimens examined by Mr. Hatchett by no means correspond 

 in character with the great mass of the lake, which in most cases, 

 would doubtless be found to be infinitely more free from combina- 

 tion with earthy substances; though from the mode of origin which 

 I have assigned to it, this intermixture may be regarded as more or 

 less unavoidable. The analysis of the stone after the separation of 

 the bitumen, as Mr. Hatchett very correctly observes, accords with 

 the prevalent soil of the country 5 and I may add, with the soil 



* Vide Linnean Trans, vol. viii. 



