"A strong, pungent, sulphureous smell, somewhat resembling that of earth-oil, is perceived on standing near the explosion; and the mud recently thrown up possesses a degree of heat greater than that of the surrounding atmosphere. During the rainy season these explosions are more violent, the mud is thrown up much higher, and the noise is heard at a greater distance.
"This volcanic phenomenon is situated near the centre of the large plain which interrupts the large series of volcanos; and owes its origin to the general cause of the numerous volcanic eruptions which occur on the island." _Batavian Trans._ vol. ix.
"These salt wells, as Dr. Horsfield terms them, and other phenomena connected with them, appear to be precisely of the same description as the mud volcano at Macalouba, in Sicily, and the eruptions described by Pallas, at Tainan and Kercha (the boundary of Europe to the south-east of Little Tartary) and no doubt owe their origin to similar causes--the extrication of gas, as well described by Dallas, in his Translation of the History of Volcanos, by the Abbé Ordinaire," page 249. All the phenomenon described in this work, as well in Sicily as at Tainan and Kercha, are to be found in Java, where, on the hypothesis of the Abbé, "the vitriolic acid liberating a great quantity of fixed air from the salts with which this argillaceous and limy mass is impregnated, is observed escaping copiously, by a general bubbling on the surface of the plain, when the substances are sufficiently diluted by rain," &c.
On the hypothesis of the Abbé it may, therefore, be doubted whether the assertion "that the Blédegs owe their origin to the general cause of the numerous volcanos on the island, is correct." Pallas conceives that the phenomenon at Kercha and Tainan may be explained by supposing a deep coal mine to have been for ages on fire, that the sea broke in upon it, that the water was turned into steam, and that the expansion occasioned thereby, and the struggle of the different gases to get free, force the upper surface, &c. but there seems no necessity for admitting the action of fire; the mud he describes is only _luke-warm_, this is precisely the case in Java.
It is remarkable that in Java, as in Sicily, in the vicinity of these phenomena, "the country around is of calcareous earth; briny springs and salt mines are found in the neighbourhood; some beds of oil of petroleum are also observed floating on adjacent stagnant waters."