POMAIN XII. VOLCANIC. 283 



dern volcanoes have lost the power of pro- 

 ducing any*/ The detached masses that 

 pass for compact lava, he acknowledges to 

 have been ejected in their solid form, by 

 the explosive power of the volcano; and 

 consequently they are not real lavas, but 

 rather natural stones, torn from the sides 

 of the mountain^. M. Dolomieu tells us, 

 that compact lavas are stones, which, after 

 having been melted, reassume their natural 

 state and appearance, without any change 

 in their external or internal properties, or 

 scarce any change^; and that some are 

 perfectly compact (that is, destitute of 

 pores) ; namely, those that are buried un- 

 der, not other lavas, but under an entire 

 and immense volcano^; he therefore gives 

 up the idea of finding these, not only in 

 the beds of modern, but even in those of 

 extinct ancient volcanoes. Hence he tells 

 us, that they are much more common in 



* Lithol. Vesuv. p. 47- 



f Ibid. 51. 



t Dei prodotti Volcan. p. 162. Ponces, 170, &c, 



Ibid. 179. 



