MODIFIED ly COMPRESSION. 143 
tube was perfectly clean. Its weight with its contents, feem- 
ed to have: fuffered no’ change: from what it had been when 
firft imtroduced. Attending, however, to the balance with 
ferupulous nicety, a {mall preponderance did appear on the 
fide of the weight. This was done away by the addition 
of the hundredth of a grain to the fcale in which the carbo- 
nate lay, and an addition of another hundredth produced in it 
a decided preponderance. Perhaps, had the tube, before its in- 
troduction, been examined with the fame care, as great a diffe- 
rence might have been detected ; and it feems as if there had. 
been no lofs, at leaft not more than one hundredth of a grain, 
which on 10.95 grains, amounts to 0.0912, fay 0.1 per cent. 
The carbonate was loofe in the little tube, and. fell out by fha- 
king. It had a yellow colour, and compact appearance, with: 
a ftony hardnefs under the knife, and a ftony fraGure; but with 
very flight facettes, and little or no tranfparency.. In fome 
parts of the {pecimen, a whitifh colour feemed to indicate partial . 
‘calcmation. _ On examining the fracture, I perceived, with the 
- magnifier, a {mall globule of metal, not vifible to the naked. 
eye, quite infulated and fingle. Poffibly the fubftance may have 
contained others of the fame fort, which may have compenfated. 
for a fmall lofs, but there could-not be many fuch, from the 
general clean appearance of the whole.. In the fracture, I faw 
here and.there {mall round holes, feeming, though imperfect-. 
ly, to. dicate a beginning of ebullition. 
I mabe a number of experiments in the fame manner, 
that is to fay, with the muzzle of the barrel upwards, in fome 
of which I obtained- very fatisfatory refults.; but it was. 
only by chance that the fubftance efcaped. the contamina-- 
tion of the fufible metal; which induced me to'think of ano-. 
ther mode of applying the comprefling weight with the 
muzzle of the barrel downwards, by which I expected to re-. 
peat with a determinate weight, all gi experiments formerly. 
made 
