ON VOLCANOES AND EARTHQ.UAKES 363 



ments of rocks ; and this also appears to be the chief 

 source of the mud which has often been supposed to 

 flow out of the volcanic opening. During the erup- 

 tion, torrents of rain fall on the mountain ; and, mix- 

 ing with the dust, produce those currents of mud 

 which seem chiefly to have overwhelmed Pompeii. 

 But, in other cases, as boiling water is also ejected, 

 either from the water of rivers, or of lakes, or of the 

 sea, getting access to the burning caverns, it is not 

 improbable that this is also an occasional source of 

 the eruptions of mud. That the fishes already men- 

 tioned, Pimelodes Cyclopum, should be ejected with- 

 out destruction, proves, that the water had, in these 

 cases, been thrown out almost at the moment of its 

 admission to the sources of heat. The torrents of 

 water which sometimes accompany eruptions, are also 

 occasionally caused by the melting of the snows on the 

 summits of the mountains ; an event which has fre- 

 quently occurred in the Andes, and been attended 

 with great destruction. 



But I must here also mention those singular pro- 

 ductions, the mud volcanoes, which exist without 

 apparent fire. One of these is found in Java, one in 

 Sicily, and others in the Crimea. That of Maccaluba 

 in Sicily, is a hill terminating in a plain of mud, which, 

 when softened by the rains, is in a state of ebullition, 

 and, when dry, is elevated, in various places, into little 

 cones with craters, whence a black mud is emitted. 

 In some seasons, the eruptions are sudden and violent, 

 and attended by slight earthquakes. Fragments of 

 rock are sometimes also ejected, together with sulphu- 

 retted hydrogen : and this general account is suffi- 

 ciently applicable to all the appearances of the same 

 nature that have been described. 



But the most interesting products of volcanoes, to 



