THE TROPIC NIGHTFALL. 59 



Macaliiba giving out bitumen, and bubbles of carbonic acid 

 and carburetted hydrogen. The mud-volcano of Saman, in the 

 Western Caucasus, gives off, with a continual stream of thick 

 mud, ignited gases, accompanied with mimic earthquakes like 

 those of the Trinidad Salses ; and this out of a soil said to be 

 full of bituminous springs, and where (as in Trinidad) the 

 tertiary strata carry veins of asphalt, or are saturated with 

 naphtha. At the famous sacred Fire wells of Baku, in the 

 Eastern Caucasus, the ejections of mud and inflammable gas 

 are so mixed with asphaltic products, that Eichwald says 

 "they should be rather called naphtha volcanos than mud 

 volcanos, as the eruptions always terminate in a large emis- 

 sion of naphtha." 



It is reasonable enough, then, to suppose a similar con- 

 nection in Trinidad. But wdience come, either in Trinidad or 

 at Turbaco, the sea-salts and the iodine ? Certainly not from 

 the sea itself, which is distant, in the case of the Trinidad 

 Salses, from two to seventeen miles. It must exist already 

 in the strata below. And the ejected pebbles, which are 

 evidently sea-worn, must form part of a tertiary sea-beach, 

 covered by sands, and covering, perhaps, in its turn, vege- 

 table debris which, as it is converted into asphalt, thrusts 

 the pebbles up to the surface. 



We had to hurry away from the strange place ; for night 

 was falling fast, or rather ready to fall, as always here, in a 



