According to Dr Nugent, who has more recently examined this lake, the bituminous substance is asphaltum, which is traversed by numerous and sometimes deep crevices filled with good water, which the inhabitants use, and in which mullet, and other species of fish are often caught. Its surface had the colour of ashes, and did not adhere to the foot, from which, however, it received a partial impression, but not so as to be dangerous to walk over it. Pieces of unaltered wood were found en veloped in the pitch. The lake contains many islets covered with long grass and shrubs, which are the haunts of birds of the most exquisite plu mage, as the pools are of snipe and plover. Alli gators are said to abound here, but Dr. Nugent did not see any of them. The asphaltum is sometimes black and hard, with a dull conchoidal fracture, but in general it may be easily cut, and its interior ap pears oily and vesicular. At a candle it melts like sealing wax, and burns with a flame which soon ceases when removed. It acquires fluidity when mixed with oil, butter or tar, and is used as pitch. Dr. Nugent found petroleum perfectly fluid in one part of the lake, and Captain Mallet, in his topo graphical sketch of the island, observes that " near Cape La Brea. a little to the south-west, is a gulf or vortex, which in stormy weather gushes out. raising the water five or six feet, and covering the surface for a considerable space with petroleum or tar." lie adds, that on the east coast on the Bay of Mayaro, there is another gulf similar to the former, which in March and June detonates like thunder, having some flame with a thick black smoke, which vanishes immediately. In about twenty-four hours afterwards, there is found along the shore of the bay ? quantity of bitumen about three or four inches thick. Captain Mallet like wise quotes Gumilla, as stating in his description of the Orinoco, that about seventy years ago, " a spot of land on the west coast of this island, near half way between the capital and an Indian village, sank suddenly, and was replaced by a small lake of pitch, to the great terror of the inhabitants." In confirmation of the truth of these statements, it may be added, that in many parts of the lake, the pitch seems actually to have overflowed like lava, and leaving the wrinkled appearance which a sluggish substance would exhibit in motion.
On first viewing the pitch lake of Trinidad, Dr. Nugent remarks, that the singularity of the scene was altogether so great, that it was some time be fore he could recover from his surprise so as to investigate it minutely.
The Mud volcanoes of Trinidad resemble those observed by Humboldt in South America. The following interesting description of them has been given by Dr. W. Ferguson in the Edinburgh Trans actions: " They are situated near Point league, the south ern extremity of the island, on an alluvial tongue of land, that has been appended to the primitive rocks, where no doubt the land originally terminated. This appendage is several miles in length, and points directly into one of the mouths of the Orinoco, on the mainland, about twelve or fifteen miles off.
" We landed nearly opposite to where we were told we should find the mud volcanoes, and after making our way about five miles through the woods, across the sandy isthmus, we came upon two plantations very pleasantly situated amidst a group of remarka ble round little hills, each from eighty to a hundred feet in height. Our path on leaving these, led us
through some very thick wood of tall trees, till we found ourselves again upon a pretty steep regu lar ascent, which had nothing remarkable in it, except the diminishing height of the trees as we went up. Only the tops of these trees, which were of the kind that usually grow near lagoons and salt marshes, at last appeared above the ground, as we opened a perfectly uniform round bare platform, of several acres, with different chimneys in the shape of truncated cones, the highest of them not exceed ing three feet, sonic of which were throwing out,with a strong bubbling noise, salt water, about as salt as that of the Gulf of Pavia, loaded as much as it could be, to preserve its fluidity, with argillaceous earth. In some of the chimneys this went on slowly, or not at all; in others it might be called a pretty active cold ebullition. The surface of the platform round the chimneys was perfectly firm, and one of our party picked up a white sea shell, of the turbinate() kind, in the act of being thrown out along with the mud.
" We afterwards procured various pyritic frag ments that had been picked up in a similar manner; but the inhabitants in the quarter assured us, that the ebullition, even during its greatest activity, was quite cold. The smooth circular platform was bounded by a perfect regular parapet of clay, about three feet in height, propped up, as it were, by the tops of the trees, that, like shrubs, were shooting out of the ground immediately behind it. This ap pcarance was most likely to be referred to the bu ried trees around, having had time to shoot out in the interval between the two last great eruptions, which takes place only during the hottest months of dry seasons, and then the noise is described to be like the loudest cannon, the mud being thrown up to the height of at least thirty feet in the air, and the theatre of the eruption being unapproachable within fifty paces.
"Close to the first volcano, but in a much more low and sunk situation, is another of precisely the same appearance and character, with only a narrow ravine between the two.
" Such an extraordinary phenomenon induced us to examine the neighbouring mounts of the cleared country, close to the nearest of which stands the residence of Alonsieure Chancelier, a French plant er, and we found them all, (bating only the erup tion) to possess the same form and composition in all respects as those we had just quitted. The platform and parapet were easily distinguishable, the chimneys only were gone, but just small pits were left in their places, filled with mud, from which air-bells rose even under our own observation, and our conductor, the intelligent manager of the estate, told us, that when these rose in salt water, a fresh eruption was to be apprehended. Ile pointed out the former site of his master's residence, half up the mount, which had been destroyed by one of these eruptions, after a period of cessation so long, that no record remained of the one that had preceded it, and he assured us, that during the period he had lived there (fourteen years) the largest mount now in activity had gained a very considerable increase of height.