Ch. VIL SOUTH AMERICA. 87 



t-ending themfelves under the plains, and traverfing 

 them in feveral directions. This being admitted, it 

 will appear, that in whatever country vjolcanoes, or 

 depofitaries of thefe fubftances, are very common, the 

 plains will be more diverfified with thefe ramifications ; 

 for we are not to imagine that it is only within the 

 bofoms of mountains that fubftances of this nature 

 exift, and that they are not diffeminated through all 

 the parts of the adjaceut region. Thus the country 

 now under confideration, abounding in thefe igneous 

 fubftances more than any other, muft, by the conti- 

 nual inllammation which neceftarily follows their na- 

 tural preparation for it, be more expofcd to earth- 

 quakes. 



Besides the fuggeftions of natural reafon, that a 

 country containing many volcanoes muH alio be every 

 where veined with ramifications of correfpondent fub- 

 ftances, it is confirmed by experiment in Peru ; where 

 we find almoft univerfaiiy mines of nitre, fulphure, 

 vitriol, fait, bitumen, and other inflammatory fub- 

 ftances, which fufiicientiy confirm the truth of thefe 

 inferences. 



The foil both of Quito and Valles, particularly 

 the latter, is hollow and fpongy, fo as to be fuller of 

 cavities or pores, than is ufually feen in that of other" 

 countries ; and confequently abounds with fubterra- 

 neous waters. Befidcs which, as I fliall prcfently 

 fhew more at large, the waters, from the ice continu- 

 ally melting on the mountains, being filtrated through 

 thefe pores during their defccnt, penetrate deep into 

 the cavities of the earth ; and during their fubterra- 

 neous courfe, moiften, and turn into a kind of pafte, 

 thofe fulphureous and nitrous fubftances; and though 

 they are not here in fuch prodigious quantities as in 

 volcanoes, yet they are fufficient, from their in 0am- 

 matory quality, to rarify the air contained in them, 

 wb.ich eafily incorporating itfeif vvith that confined in 

 the innumerable pores, cavities or veins of the earth, 



G 4 CO mp re Ifes 



