166 Of the Sulphur 



* I afterwards placed it in the focus of a burn- 

 € ing-glafs, but could neither make it take fire, 

 c nor melt it ; only it boiled, and gave forth a 



* fmell of aqua fortis : after leaving it in the fire 

 ' fo long, 'till it fumed no more, I found it de- 



* creafed almoft an half, and what remained ap- 



* peared black, mining, flaky, infipid, and in no 

 c .manner altered by the burning-glafs. 3 (This is, 

 certainly, a circumftance that merits great notice, 

 in particular, that it mould refufe to yield to one 

 of the mofl quick and violent fires of vitrification 

 in nature, namely, that of the fun.) 



c Now, this matter I fuppofe to be the earthy 

 ' part of common fulphur. I weighed it, and 

 4 found it to be one ounce, and almoft one drachm, 

 c that is, about i of the whole : ' (that is, of four 

 ounces of fulphur.) 



c Now, as I could not force it by the burning-* 



* glafs alone, and per fe •, upon adding a little 

 \ borax, it melted to a glafs of a grey-brown co- 



* lour : this glafs, after (landing for fome time in 

 c a moifl place, I found, at laft, flrike a grey- 

 4 green efflcrefcence all around ; whence I learn, 

 4 the fulphur employed in this procefs, to have held 

 c fome copper, but in fo fmall a quantity, as to 

 \ be infeparable from it in a metallic form.' 



* The fume (till forced out by the burning glafs, 

 £ is, in all appearance, the remains of the ratty 



* earth and acid fait of common fulphur, which the 

 J common fire could not force out. I apprehend 

 ' this fume to have contained as much oily matter 

 4 as acid fait; confequently, in this caput mortuum y 



* to be about three drachms of fait more, which, 



* with 



