C ] 
merit. A tin veffel, about nine inches in diameter, 
' was fet on the fire, fo that the water on one fide only 
boiled violently, but the motion arifing from thence 
made all the water circulate through the vefiTel ; and, 
therefore, all the water (after the vefiel had boiled 
for fome time) mu ft have acquired the fame degree 
of heat. I then held a mercurial thermometer, with 
Fahrenheit’s fcale, under the water ; where it was 
juft out of the reach of the bubbles, it rofe there 
no higher than to 2 1 1 ; but when it was held among 
the bubbles, where they afcended thickeft, it rofe 
to 212, which is ufually reckoned the mean heat of 
boiling water, though it feems rather to be the heat' 
of the (team contained in the bubbles ; and, there- 
fore it is fomewhat greater than the heat which wa- 
ter will bear without being turned into fleam. Thc' 
heat of the water was not then fo great as it fome 
times is, for the atmofphere was then very light, the- 
barometer flanding at 29. 
From what has been faid, it follows, that the de- 
grees of heat neceflary to raifc thefe bubbles in any 
fluid, and make it boil, will be greater as the fluid 
is more flrongly prefiedi and as its particles are more 
tenacious or vifcid. And this we find is exadtly 
agreeable to experience. For fpirit of wine, which' 
is a fluid very light, eafily rarefied, and in no degree 
vilbid, will boil with a lefs heat than water does. 
But mercury, whofc particles are heavier, and oil op 
pitch, whofe particles are more vifcid, than thofe of 
water, will require a much greater degree of heat to 
make it boil than water does. And it is knowiv 
that water boiled in a clofe veffel, where it is firong- 
ly prefled by the confined elaflic fleam, will become 
much 
