[ *57 ] 
this very extraordinary phenomenon, until the truth 
of it could be fufficiently authenticated. This has 
very lately been done by Profeffor Braun, who firff 
made the experiments, and who prefented an account 
of them to the Royal Academy at Peterfburg, a 
printed copy of which has been communicated by 
him to the Royal Society. 
Profeffor Braun obferves, that every age has its 
inventions, and that the difeovery of fome things feem 
to be refer ved for particular perfons. To this, the hi- 
ftory of fciences in all ages, more particularly of the 
late and the prefent, bears witnefs fufficiently, by the 
invention of the air-pump, barometers, thermometers, 
optical inftruments, electricity, more particularly the 
natural, artificial magnets, phofphorus, the difeovery 
of the aberration of light, and of many other things 
in natural philofophy. He does not know, whether 
the congelation of mercury, which it was his good 
fortune to difeover, may not be ranged among thefe : 
for who did not confider quickfilver, as a body, which 
would preferve its fluidity in every degree of cold ? 
Neither was the faCt otherwife, if this is underftood 
of natural cold, fuch as it has been found in any part 
of the globe, hitherto difeovered. But if it fhouid 
happen, that the natural cold fhouid ever be fo in- 
tenfe as artificial cold has been found to be, the 
whole globe would have a different face , as men, 
animals, and plants, would certainly be deftroyed. 
He did hint fome time fince, in a differtation upon 
the degrees of heat, which certain liquors and certain 
fluids would bear before they boiled, and the degrees 
of cold they refpedtively bore, before they were con- 
verted into ice, that there was a fufpicion, that the 
mercury 
