Now and then this ‘Salse,’ so quiet when we saw it, is said to be seized with a violent paroxysm.  Explosions are heard, and large discharges of mud, and even flame, are said to appear.  Some seventeen years ago (according to Messrs. Wall and Sawkins) such an explosion was heard six miles off; and next morning the surface was found quite altered, and trees had disappeared, or been thrown down.  But—­as they wisely say—­the reports of the inhabitants must be received with extreme caution.  In the autumn of last year, some such explosion is said to have taken place at the Cedros Salse, a place so remote, unfortunately, that I could not visit it.  The Negroes and Coolies, the story goes, came running to the overseer at the noise, assuring him that something terrible had happened; and when he, in defiance of their fears, went off to the Salse, he found that many tons of mud—­I was told thousands—­had been thrown out.  How true this may be, I cannot say.  But Messrs. Wall and Sawkins saw with their own eyes, in 1856, about two miles from this Cedros Salse, the results of an explosion which had happened only two months before, and of which they give a drawing.  A surface two hundred feet round had been upheaved fifteen feet, throwing the trees in every direction; and the sham earthquake had shaken the ground for two hundred or three hundred yards round, till the natives fancied that their huts were going to fall.

There is a third Salse near Poole River, on the Upper Ortoire, which is extinct, or at least quiescent; but this, also, I could not visit.  It is about seventeen miles from the sea, and about two hundred feet above it.  As for the causes of these Salses, I fear the reader must be content, for the present, with a somewhat muddy explanation of the muddy mystery.  Messrs. Wall and Sawkins are inclined to connect it with asphalt springs and pitch lakes.  ’There is,’ they say, ’easy gradation from the smaller Salses to the ordinary naphtha or petroleum springs.’  It is certain that in the production of asphalt, carbonic acid, carburetted hydrogen, and water are given off.  ‘May not,’ they ask, ’these orifices be the vents by which such gases escape?  And in forcing their way to the surface, is it not natural that the liquid asphalt and slimy water should be drawn up and expelled?’ They point out the fact, that wherever such volcanoes exist, asphalt or petroleum is found hard by.  The mud volcanoes of Turbaco, in New Granada, famous from Humboldt’s description of them, lie in an asphaltic country.  They are much larger than those of Trinidad, the cones being, some of them, twenty feet high.  When Humboldt visited them in 1801, they gave off hardly anything save nitrogen gas.  But in the year 1850, a ‘bituminous odour’ had begun to be diffused; asphaltic oil swam on the surface of the small openings; and the gas issuing from any of the cones could be ignited.  Dr. Daubeny found the mud-volcanoes of Macaluba