2 8 Mr. de Lee on 
of the veffel quite open. The fecond veffel has the fame di- 
menfions as the firft ; but its back is foldered, and its front is 
of woven brafs wire. This veflel may be applied to the back 
of the former, in fuch manner as to make of both one (ingle 
veffel, which, when the Jlider of the fore-part is taken off, is 
only divided by a vertical partition of woven brafs wire. The 
ufe of that fecond veffel is to produce extreme drynefs in the 
other ; for which purpofe it is filled with large pieces of quick- 
lime taken from the kiln. When that veffel is not ufed, it is kept 
in a tin box which it fills intirely ; and when it is in, as well as 
while it is out for ufe, that box is kept (hut with putty, by 
which means the fame lime may ferve many times in the fol- 
lowing manner. 
44. When I want to produce extreme drynefs in the firft 
veffel, I apply to it the fecond, faftened with hooks ; I then 
pull out the Jlider of the firft, and flop with putty the chinks 
between them. When that firft operation is completed, I put 
again x\\o, Jlider to the fore-vefl’el, and take off the other. In 
this laft operation, fome moijlure might be introduced through, 
the chinks of the Aider, before they are again flopped with putty ; 
efpecially as the deftruftion of moijlure in the veffel has made 
room for more air to come in ; but I prevent it by making firft 
the apparatus fenfibly warmer than it was when I put on the 
lime-veffel ; by which means, in the little time employed for 
the operation, the motion of the air is from the infide to 
the outfide, which prevents all accefs of moijlure in the veffel. 
45. To that firft operation fucceeds that of a gradual intro- 
duction of moijlure into the apparatus. It would have been 
ufelefs to apply to that procefs the means I had imagined, for 
fpreading fucceffive equal quantities of water in a clofe veffel ; 
for the evaporated water depofiting itfelf in part, more or lefs, 
on every furface, and the furfaces, efpecially of glafs, being 
very 
