§ Mr. de Luc on 
natural philofophy. And in the mean time thofe anomalies 
are very interefting in themfelves ; as, from their laws, they 
feem to point out fome modification of eohfion, as being the 
immediate caufe of elafiicity in folids. If I can find time to put 
in order a number of observations and experiments I have 
made in that refped, I intend to make it the fubject of a 
Paper, in which I fhall examine, from a general refult of 
thofe phenomena, the comparative ufe of weights and Springs 
for keeping ftretched the hygrofcopic fubftance in hygrometers. 
io. After fixity in the degree of drynefs produced by lime 
jq manner I have explained, the next point to be examined 
In refpeft of my theory, was, if the nature of the fubftance 
brought to a white heat, had any influence on the degree of 
drynefs thereby produced ; and in order to try at once the effedl 
of a very great difparity, I chofe fuch a Jand-Jlone as is not 
affected by acids, and ftrikes fire from fteel, before and after 
having been incandefcent. The firfl experiment I made was 
with a view of finding the comparative capacities for moifiure 
between that Jlone and lime. For that purpofe I took fuch 
pieces of them as might be readily reduced to half an ounce 
while incandefcent ; which being done, I put them into brafs 
cups, fitted to a fcale, and I inclofed them under a 
s?lafs veflel inverted over water. I weighed thofe fubftances 
from time to time ; each of them continued to acquire weight 
during five weeks ; at which time the fand-ftone had gained 
* part of its original weight, and the lime - this laft was 
at that time all cracked and fallen in fmall fragments, eafily 
reduced to powder ; th z fand-ftone ftruck fire as before. I next 
prepared a cylindrical tin veffel, io inches in diameter and 14 
inches high, with a glafs top, which I filled with fragments 
of that ftone, treated as the lime ; and when it was cooled, I 
