io The Subject Propounded. 



* c in a hole in the earth, and covered all with 

 4C earth. In about eight or nine hours after, the 

 " earth beginning to heave, heat and fpring up, 

 <c there burft out a fulphureous hot fume and an 

 cc actual flame, which enlarged the rents, and a 

 <c yellow black powder fettled fuperficially round 

 * c about them. The earth remained a long time 

 cc warm : and when I came, after this, to dig 

 <c out the pot, I found remaining only a black heavy 

 " powder, &V. This procefs fucceeds better in 

 * c fummer than winter, as the fun's heat may 

 * c be fuppofed to have a better effect on the ful- 

 €c phur and iron." He then proceeds to ob- 

 viate fome objections. As, i. Whence volca- 

 nos come to have their air, without which there 

 can never happen any accenfion. 2. How a- 

 midft much moifture, as the water of the clouds, 

 the matter of thunder and lightning, fliould come 

 to take fire : as to the firft, 'tis eafy, fays he, to 

 conceive that the earth, a porous, permeable bo- 

 dy, is equally filled, as it is invironed, with air. 

 The fecond he endeavours to explain by means of 

 that experiment, where, in making iron-vitriol 

 with the acid of vitriol and common water, the 

 Fumes arifing from the glafs body take fire, and 

 burft out into actual flame, by approaching a 

 candle to them, as though they were fpirit of 

 wine, notwithftanding thefe inflammable fulphur- 

 particles are envelop'd in water *. 



Laftly, As to Therms or hot fprings, I ima- 

 gine no one, acquainted but fuperficially with 

 their internal conftitution and nature, will call in 

 queftion their partial orgination from the yellow- 

 ifh or fulphur-iron pyrites ; I fay partial^ and not 

 total origination ♦, in regard that thefe, in parti- 

 cular the acidula, as the Caroline^ &c. carry along 



witli 



* Mem, de TAcad. Roy. l'aon, 1700, p. 131. Se^. 



