IO 
Mr. de Luc on 
retained a fenfible quantity of evaporable water, the increafe of 
beat made them lofe fome weight , which they regained partly 
when the beat returned to the fame point. But that effect di- 
minifhed by degrees ; and, at laft, a change of 30° of Fahren- 
heit did not produce any fenfible change of weight in thofe 
fubftances, though they were fuch as had a great capacity for 
moijlure . An hygrometer placed near the beam y was then at 
the point taken in the lime-vejfel. That Angle experiment con- 
firms all the previous confiderations from which I had expected 
abjolute drynefs from incandefcence . 
Of extreme 7?ioiJlure. 
13. The fecond propofition I had fketched in my firft paper, 
is this “ that water ^ in its liquid ftate, is th tonly fure immediate 
“ means of producing extreme moiflure in hygrofcopic bodies.” 
14. Moiflure , the nature of which we are firft to determine, 
may be confidered in three different cafes. — lft, In fubftances 
which have an affinity with water ; by which their moleculae 
and thofe of water may unite, and form a new compound. — 
2dly, In fubftances which have no affinity with water , but to 
which water has a tendency to adhere ; by which caufe it 
enters their capillary pores.— 3 dly, In the medium , or fpace free 
from vifible bodies. I have not undertaken to difcover what, 
in the firft of thefe cafes, might properly be called moijlure ^ and 
its degrees ; as I forefaw great difficulties in that undertaking, 
which befides was unneceffary to my principal purfuit : 
therefore I come immediately to the fecond cafe. 
15. When I wrote my work -Idees fur la Meteorologie , having 
not yet made fome experiments I had in view to verify the opi- 
nion I entertained, that vegetable and animal fubftances, as 
well 
