the Congelation of Quickfilver. 344 
irigo rific mixture appears to have been made with the vitriolic 
acul ; and the natural cold of the air at Northampton that day, 
the 30th ol January, was -I- 9 0 . It is fcarcely poflable to de- 
termine how far he fucceeded. The quickfilver of his thermo- 
meter funk into the bulb, and it, as well as fome in a phial, 
contracted what Ur. fothergill calls a film on the top; but 
unlefs the fcale ot his inilrument went below - 40°, or fome 
folid cryftals were formed, fuch as M. braun and others, ob- 
ferved at the commencement of congelation, nothing can be 
collected with certainty from this experiment. 
Though the cold of this hard winter was not fufficient, 
either in England or Holland, for the convenient performance 
of experiments on the congelation of quickfilver, yet in many 
parts of the European continent, not farther north, it was 
fully intenfe enough for that purpofe. The very morning 
when Dr. bicker lucceeded fo imperfeCtly at Rotterdam, the 
thermometer funk to — 22 0 at Rudolftadt, lituated a degree 
more to the fouthward ; and it had been the preceding day as 
low as — 1 8° at Berlin *. 
§ 6. I find no further attempts to freeze quickfilver till the 
year 1781, when Mr. hutchins re fumed this fubjeCt with fuch 
brilliant fuccels. The preceding experiments had done little 
more than prove that quickfilver might be rendered folid by 
cold, and fhew what fort of fubftance it was in that Rate. 
Nothing fit is faCtory had been afeertained with regard to its 
freezing point, or the degree of a thermometer at which it 
ceafes to be a melted and becomes a folid metal. It muff not 
be fuppofed, however, that the gentlemen who were engaged 
* Befchaftigungen der Berlinifchen Gelellfchafc Naturfurfch. Freunde. B. 31. 
P- 575. 576. 
Vol. LXX 11 I. Z z in 
