378 ESSAYS and OBSERVATIONS 



the coal. By the way, this may be fomc 

 fort of proof, that the volatile acid part 

 of nitre is not more a fimple elementary 

 matter than is the fixed part. 



No T w ITHSTANDING what has beea 

 ihewn, concerning the flrong attradlion 

 between the particles of fpirit of nitre and 

 thofe of filver, and the difficulty of fepa' 

 rating them by the force of fire ; yet, if 

 a piece of clean copper is put into a folu" 

 tion of filver in fpirit of nitre, the faline 

 particles moft readily fhake off the filver, 

 and diflblve the copper : Which fhews 

 that the particles of copper have a flrong- 

 erattradive power, with refpefl to the fpi- 

 rit of nitre, than the particles of filver 

 have; which difference of attraction will 

 probably arife from the different bulk, 

 figure, or denfity of the particles 

 of the two metals, the acid being the 

 fame. The fame thing may be faid 

 of iron, zinc, chalk, volatile alcaline 

 fait, and fixed fait, each of which attract 

 ipirit of nitre more flrongly than filver 

 does, and the lait more than the preceed- 



Here 



