MINERALOGY. 135 



SECT. CXXV. 



C Vitriolic acid united with phlogiflon, Acidum 

 vifrioli phlogifto combinatum. The fulphur 

 kind, Sulphura. See Seel. cli. 



SECT. CXXVL 



D. Vitriolic acid faturated with alcaline fait, 

 Acidum vitrioli (dealt miner alt faturatum. 



as in general is underwood by that expreffion, viz. that the 

 heterogeneous particles are not xery obvious, nor of any 

 great cor.fequence. 



The phlogiilon which is contained in the black alum 

 Elates, mav perhaps during the calcination difpofe the iron 

 to be eafier diilblyed ; and it mav alfo occafion the black 

 colour in fome of them, that even contain but very little of 

 iron, as moft likely in part of thofe from Nas (c. 2.). 



If is not eafilv determined, whether the earth in the alum 

 flates is argillaceous or quartzofe, or whether it is a black in- 

 durated humus, or mould, becaufe all thofe three earths, 

 when diflblved in the vitriolic acid, produce alum. The Co- 

 logne pipe-clay is a plain proof of the rlrft ; the quartzofe 

 earth, in liquor Jflicum, of the fecond ; and aluminous foflil- 

 woods are actually employed for making alum in Bohemia 

 and HeiTe. Thefe earths may, or may not,,contain iron; 

 however, they prevent, in the former cafe, the phlogiiton, 

 together with the vitriolic acid, from mineralizing all the 

 iron, ard making a marcafite of it, excepting here and there, 

 in fome infignifkant quantity, as in cracks, or when it meets 

 with fome heterogeneous bodies, a c {hells, infects, &c. in the 

 earths. There is a remarkable progreifion from the 

 Hack alum flates to the pit-coal, in proportion as the quan- 

 tity of the phiogiiton encreafes, and the quantity of the 



h decreafes (Sect. ciix.). It is this phlogiflon which 

 makes this alum fiate capable of burning by ;tfeif, when it is 

 or.ee lighted ; whereir. it differs from the aium ores of Lumini, 

 which, in order to be brought to moulder, require the being 

 expefed to the heat cA the fan, 2nd to be fprinkled with water : 

 former has B»(b within itf:H" fufficien: matter to fponta- 

 rreoully flame upon certain occafions, according to what the 



ii 4 celebrated 



