C 162 ] 
Hitherto our profeffor had only feen the mercury 
fixed within the bulb of his thermometers. Thefe 
he was unwilling to break. He was, however, de- 
firous of examining the mercury in its fixed flate, 
and therefore determined to break his thermometers in 
the next experiments. It was feveral days before he 
got other thermometers, which exa&ly correfponded 
with thofe he had already employed. 
When thefe were procured, the natural cold had 
fomewhat relented. In the former experiment, the 
thermometer flood at 204 j it was now at ipp. In 
making the experiment, he varied the manner a little. 
He firft put the bulb of the thermometer into a glafs 
of fnow, gently preffed down, before he poured on 
the aquafortis ; he then, in another glafs, poured the 
aquafortis upon the fnow, before he immerfed his 
thermometer therein ; he then, in like manner, put 
the fnow to the aquafortis, before he put his ther- 
mometer therein. Which ever of thefe ways he 
proceeded, he found the event exactly the fame ; as 
the whole depended upon the aquafortis diffolving 
the fnow. When he had proceeded fo far, as to 
find the mercury immoveable, he broke the bulb of 
the thermometer, which had already been cracked 
in the experiment, but the parts were not feparated. 
He found the mercury folid, but not wholly fo, as 
the middle part of the fphere was not yet fixed. The 
external convex furface of the mercury was perfectly 
fmooth ; but the internal concave one, after the finall 
portion of mercury, which remained fluid, was poured 
out, appeared rough and uneven, as though com- 
pofed of fmall globules. He gave the mercury feve- 
ral ftrokes with the peflle of a mortar, which flood 
near 
