[ i6o ] 
to have added 20 degrees to the cold formerly 
known. 
But reflecting, that this was not all the fruit he 
expected from thefe experiments, he determined to 
purfue them; but at the fame time, however, to 
vary the manner of them. By good fortune, his 
ice was all gone, and he was compelled to ufe fnow 
in its ftead, after having firft tried, and found the 
fnow of the fame degree of cold with the air, at this 
ti*ie 203. The fnow, the thermometer, and the 
aquafortis, being of the fame temperature, he im- 
merfed the thermometer in fnow, contained in a 
glafs ; and, at firft, only poured a few drops of the 
aquafortis upon that part of the fnow, in which the 
thermometer was immerfed ; upon which he ob- 
ferved the mercury to fubfide to 260. Elated by this 
remarkable fuccefs, he immediately conceived hopes, 
that thefe experiments might be carried further : nor 
was he deceived in his expectations ; for repeating 
the experiment in the fame fimple manner, he poured 
on only fome more aquafortis, and immediately the 
mercury fell to 380. Upon which he immerfed the 
thermometer in another glafs filled with fnow, before 
it had loft any of this acquired cold ; and at length, 
by this third experiment, the mercury fubfided to 
470 degrees. When he obferved this enormous de- 
gree of cold, he could fcarce give credit to his eyes, 
and believed his thermometer broke. But, to his 
infinite fatisfaCtion, upon taking out his thermometer, 
he found it whole ; though the mercury was im- 
moveable, and continued fo in the open air twelve 
minutes. He carried his thermometer into a cham- 
ber, where the temperature of the air was 1 25 de- 
grees; 
