;q.2 Dr. BLAG den's Hijlcry of 
coulcf reduce the thermometer by artificial cold, the tempera- 
ture of the air being then -f 2°. He could not bring the mer- 
cury lower than — 94 0 , at which point it (food immoveable ; 
and upon breaking the bulb he law with certainty that the 
outer part of the quickfilver had loft its fluidity, and was 
thickened to the confiftence of an amalgam ; it fell out of the 
bulb in little bits, which bore to be flattened by prcfliire, with- 
out running into globules like the inner fluid part. 
Next day, when the thermometer flood at + 8°, he repeated 
the experiment with all poflible exa&nefs, after M. braun’s 
manner ; but could not obtain a greater defcent of the mercury 
than to 8o° under o, and did not again break his thermometer. 
The firft account I faw of thefe experiments was in an ex- 
tract from the Altona Poft*, in the German language, which 
Sir Joseph banks had the goodnefs to procure from Gottin- 
gen at my requeft ; but as they are confirmed by Profeflor 
van s win den iti his Obfervations on the cold of 1776-n 
there can can be no doubt of their authenticy ; and they afford 
a proof that the freezing point of quickfilver cannot be lower 
than - 94 0 , as it funk only to that degree, and yet was in part 
congealed. 
§ 5. The other gentleman who tried theeffeT of this fevere 
cold in 1776 upon mercury was Da antiionv fothergill, 
at Northampton, and the account of his experiment may be 
feen in the Philofophical Tranfa&ions for that year ||. His 
* Altona'e'r Reichspostreuter, 1776. N° 24. Feb. 24. 
f Obfervations fur le froid rigoureux du Mois de Janvier, 1776, p. 
277. 
(! Vol. LX VI, p. s 8 9 . 
frigorific 
