[ 161 ] 
grees; and, after fome minutes, the mercury being 
restored to its fluidity, began to rife. But to be cer- 
tain, whether this thermometer had received any in- 
jury, and whether it would yet correfpond with his 
thermometer, which he keeps as a ftandard, he fu- 
fpended them together, and in twenty minutes the 
thermometers correfponded one with the other. 
The thermometers, which our author ufually em- 
ploys, have a fpherical bulb, and their fcale is divided 
into 1200 parts, of which doo are above the cypher, 
which denotes the heat of boiling water, and doo be- 
low that heat. A thermometer of this conftrudtion 
was ufed in inveftigating the heat of boiling mercury 
and oils. He had another thermometer, of which 
the fcale went no lower than 3 do degrees below the 
cypher, denoting the heat of boiling water. He re- 
peated the former experiment with this, and the mer- 
cury very foon defeended fo, that the whole was con- 
tained in the bulb, which, however, it did not quite 
fill. The mercury in this bulb was immoveable, 
even though he fhook the thermometer ; until about 
a quarter of an hour, it began to afeend in the open 
air ; and it continued to afeend, till it became higher 
than the circumambient air feemed to indicate. He 
was flruck with this extraordinary phenomenon, and 
very attentively looked at the mercury in this ther- 
mometer, and found certain air bubbles interfperfed 
with the mercury, which were not in that of the 
other thermometer. From thefe, and other experi- 
ments (it would be unneceflary to recite them all), 
he was fatisfied, that the mercury in thefe thermo- 
meters had been fixed and congealed by the cold. 
Vol. LII. Y Hitherto 
