APPENDIX. 315 
at lead twenty Minutes. For greater Cer- 
tainty, he repeated this Experiment twice 
and found the Event the fame. So the 
afeending Vapours did in vacuo acquire 
three Degrees of Heat, the refrigerating 
Mixture twenty one Degrees of Cold ; it 
at firft increafed in Degrees of Cold, but 
afterwards acquired Heat, as the Mixture 
abated of its Emotion ; for while there 
was a great Effervefcence Co long the Cold 
continued. There was a remarkable Dif- 
ference between this Experiment in vacuo^ 
and the other in the open Air, where the 
afeending Vapour was remarkably warm, 
‘‘ but in vacuo there was no Warmth given 
“ to the upper Thermometer till after the 
EflFervefcence was over, when the Fumes 
did not afeend.’* Whence I fufped that 
the Heat which the upper Thermometer 
then acquired, might be owing to the Heat 
communicated to it, from the Mixture be- 
low, which being at a Diftance from it could 
not communicate its whole Heat, viz. feventy 
four Degrees : We may hence alfo conclude 
that in the open Air, the Aftion and Re- 
action of the Air, greatly increafed the Elfer- 
vefcence, and confequently the Heat of the 
Fumes. ‘‘78. The 
