from the Pyrites. 277 



dies manifefting fuch an effect with acids, as me- 

 tals do, are and muft be aicali's. 



True it is, acids fland oppofed to aicali's, and 

 are of a quite different mixtion from them ; but 

 let us only reprefent to ourielves the incalefcence 

 happening, under a due treatment, between quick- 

 filver and ieaf-filver; here we have neither acid 

 nor alcali, and yet the union happens with an ef- 

 fervefcence : and what is (till more remarkable, no 

 fuch. effecl: appears with filed filver, which is 

 equally a filver with the former, even though the 

 fame quickfilver be employed ; fo that we fee this 

 effect is only owing to external, mechanical caufes, 

 the filver being beat thin, becomes the more 

 expofed to the action of the quickfilver, and there- 

 by rendered more receptive, as the latter may, 

 with more quicknefs and briiknefs, lay hold on 

 the filver, and thus, from a fudden brifk action 

 and re- action, an incalefcence muft enfue, which 

 in a flower degree thereof cannot. 



The appellations given the feverai parts of vi- 

 triol feem in general proper. The acid fait, 

 which commonly appears in a fluid form, lodges 

 either in a water, and then it is called fpiritus vi- 

 triolic or in a thick liquor, and then called oleum 

 vitriolic or it is fulphureous, when it gains the ap- 

 pellation fpiritus vitrioli fulphureus^ or volatilise or 

 it (till lies at reft in a metallic earth, and then it is 

 denominated gilla. Now here the feverai appella- 

 tions exhibit fomething different, and fo are nei- 

 ther fuperfluous, ambiguous, nor equipollent. 



The vitriol-earth is either yellowifh, or of a 

 brown-red caft , the yellowifh is, either a fulphur or 

 crange-ydhw. The fulphur yellow is> in the firft 



T 3 place 



