Chap, i.] Opinions of Bacon, Boyk, HomZerg, &c. 87 



indeed the Epicureans, as well as the Peripatetics, 

 feem to have confidered fir : as a .diftinct elementary 

 fubftance, capable of combining with the other ele- 

 ments, but by no means the matter from which they 

 are originally generated. 



The hiftory of error can afford but little inftrucftion, 

 otherwife volumes might be filled with the fantaftical 

 opinions which have been from time to time eatertain- 

 ed concerning the element of fire. On the revival of 

 letters and philofophy, our illuftrious Bacon, in a trea- 

 tife exprefsly written upon the fubject *, endeavours 

 to prove, that heat is no other than an inteftine motion 

 or vibration in the parts of bodies ; and he was fol- 

 lowed by mod of the philofophers of this kingdom, 

 during the laft century. The opinion of Bacon is fup- 

 ported by a variety of facts, which are adduced by 

 Mr. Boyle in a diflertation on the mechanical origin of 

 heat and cold j- ; nor does the fyftem appear repugnant 

 to the fentiments,of Newton; though he fpeaks of it 

 with that diffidence which is always obfcrvable in his 

 writings, when treating of facts not abfolutely demon- 

 ilrated by experiments of his own J. 



Notwithftanding the reputation of the Englifh phi- 

 lofophy, this theory was received with great reluctance 

 abroad. The celebrated Homberg, Sgravefend, and 

 Lemery the younger, afTert, that fire is a diflinct fub-r 

 fiance or body, which enters into combination with, 

 all other bodies, pervades all bodies, and may be again 

 expelled from them by violent motion or compreffion, 



* De Forma Calidi. 



f- Mr, Boyle, howerer, though thus apparently deceived with 

 refpeft to the caufe of heat, in another eflay reafons juftly with re- 

 fpeft to its effe&s. He confidcrs ice not as the preternatural (late 

 of water, but water as ice preternaturally thawed by heat. 



Boyle on the nat. and preleruat. State of Bodies f 

 I Optics, 318.349. 



G 4 though 



