MODIFIED ly COMPRESSION. 125 
On the 2d of January 1804, I made an experiment with 
marble and chalk, with the addition of 1.1 grain of water. I 
aimed at a low heat, and the pyrometer, though a little bro- 
ken, feemed clearly to indicate 22°. Unluckily, the muzzle 
of the large tube, which was clofed as ufual with chalk, was 
placed uppermoft, and expofed to the ftrongeft heat. I found 
it rounded by fufion, and ina frothy ftate. The little tube came 
out very clean, and was fo nearly of the fame weight as when 
put in, that its contents had loft but 0.074 per cent. of the weight 
of the original carbonate.’ The marble was but feebly aggluti- 
nated, but the chalk was in a ftate of firm limeftone, though it 
muft have undergone a heat under 22°, or that of melting fil- 
ver. This experiment is certainly a moft remarkable one, fince 
a heat has been applied, in which the chalk has been chan- 
ged to hard limeftone, with a lofs lefs than the rooodth par 
of its weight, (exactly +--+) ; while, under the fame circum- 
ftances of preflure, though probably with more heat, fome of 
the fame fubftance had been brought to fufion. What lofs of. 
weight this fufed part fuftained, cannot be known. 
On the 4th of January, a fimilar experiment was made, like- | 
wife with 1.1 grain of water. The difcharge of the metal 
was accompanied with a flafh of flame. The pyrometer in- 
dicated 26°. The little tube came out quite clean. Its con- 
tents had been reduced from 14.53 to 14.46, difference 0.07 
grains, being. 0.47 per cent. on the original carbonate, lef. 
than one two-hundredth part of the original weight, (exactly 
siz). The chalk was in a ftate of firm faline marble, but with. 
no unufual qualities. 
THESE two laft experiments are rendered ftill more intereft-- 
ing, by another fet which I made foon after, which fhewed, 
that one effential precaution in a point of fuch nicety 
had been neglected, in not previoufly drying the carbonate. 
In feyeral trials made in the latter end of the fame month, 
I 
