Bortttneof&ualttie** u 



is Necejfary. As 3 for inflance^ when 

 pure Cold is by Heat onely brought 

 to fufion, and consequently to the 

 ftate of fluidity, and upon the remif- 

 fion of that heat D grows a folid and 

 confiftent body again., what addition 

 or expulfion or change of any of the 

 tria prima does appear to be the caufe 

 of this change of confidence ? Which 

 is eafie to be accounted for according 

 to the Mechanical way, by the vehe- 

 ment agitation that the fire makes of 

 the minute parts of the Gold to bring 

 it to fufion ; and the cohefion of thofe 

 parts ? by vertue of their gravity and 

 fitnefs to adhere to one another, 

 when that agitation ceafes. When 

 Venice Glafs is meerly by being bea- 

 ten to pouder deprived of its Tranf- 

 parency and turned into a body opa- 

 cous and white, what need or ufe of 

 the tria prima have we in the expli- 

 cation of this Phenomenon > Or of 

 that other which occurs, when by 

 barely melting down this white and 

 opacous body it is deprived of its 

 opacity and colour > and becomes 



diapha- 



