DOMAIN XII. VOLCANIC. 



tions any compact lavas. Gioeni, in his 

 catalogue, entirely omits this distinction; 

 and M. Dolomieu acknowledges, that not 

 a single specimen of compact lava is to be 

 found in the cabinet of Prince Biscari. 



" Those, on the other hand, who, guided 

 by system, bestow the name of lava on 

 stony masses which they suppose to have 

 anciently flowed, either from real still sub- 

 sisting, or imaginary ancient extinct, vol- 

 canoes, find compact lava entirely destitute 

 of pores, very scarce indeed in the sup- 

 posed currents from modern, but in great 

 plenty in those which they ascribe to their 

 fictitious volcanoes now extinct, as well as 

 in the yery bowels of those volcanoes. 



" Gioeni after telling us, from Dolomieu, 

 that compact lava occupies the centre of 

 the beds of lava, and porous lava the upper 

 part, acknowledges that this gradation sel- 

 dom takes place : c few, however/ says he, 

 * are the visible currents of lava on Vesu- 

 vius, in which we meet this gradation/ It 

 seems he should rather have said, none; 

 for, some lines after, he tells us, * that mo- 



