37^ ESSAYS AND OBSERVATIONS 



part of the fpeclfic gravity of filver: Yet 

 thefe particles, thus fufpended, differ in 

 nothing, when freed from the acid, but 

 bulk from granulated filver, or the bits 

 rubbed off plate by a fine file. That this 

 power of attradion between the particles 

 of fpirit of nitre and thofe of filver muft 

 be very great, will appear, if we confider, 

 firft, that it requires a very great heat to 

 melt filver; but this melting is nothing 

 elfe than, by the force of fire, to overcome 

 the cohefion among the particles of filver, 

 and bring the mafs to a ftate of fluidity, 

 fo that the particles may eafily move and 

 Aide one upon another while that degree 

 of heat lafts j but fpirit of nitre produces 

 the fame or rather a greater effed. In 

 the next plape, though fpirit of nitre is of 

 itfelf pretty volatile, yet, when it has dif- 

 folved filver, the faline parts adhere fq 

 firmly to the metallic, that a very ftrong 

 degree of heat is required to feparate 

 them ; for, if a folution of filver is fet 

 in a heat that would make water boil, the 

 light and watry parts indeed fly off, but 

 afterwards the evaporation goes on flow- 



ly. 



