[ 6 7 b ] 
LXIV. An Account of artificial Cold pro- 
duced at Peterfburg : By Dr . Himfel. In 
a Letter to Dr. De Caftro, F. R. S. 
Tranjlated from the French by James Par- 
fonsj M, D . F. R* S. 
Read May i. ✓'""v N the 14th of December [i 7 f 9 ] we 
1760. had, at Peterfburg, the mold ex- 
ceffive cold weather that ever was known, even to 
205 degrees of De Lifle’s thermometer. At that time 
Profeffor Braun repeated Fahrenheit’s experiments, 
in order to produce exceffive cold by means of fpirit 
of nitre combined with fnow. He faw, with fur- 
prize, the quickfilver fall confiderably in the ther- 
mometer, and defcend even to 4 7 ° degrees at laft 1 
there the quickfilver remained fixed in the open air 
for the fpace of a quarter of an hour, and did not 
begin to rife till it was carried into a warm room. 
He repeated the fame experiment, firft with the fame, 
and then with another thermometer, with the fame 
fuccefs. The immobility of the quickfilver made 
him conjecture, that it might be frozen, or become 
a folid body. But as Mr. Braun had not broken 
the glaffes, he could only at that time form a con- 
jecture. On the 17th he produced, again, cold 
equal to that of the 14th ; but on that day there 
was no experiment made; and Mr. Braun commu- 
nicated his difcovery at a meeting of the academy* 
On the 25th of December in the morning, between 
nine and ten, De Lifle’s thermometer was at the 199th 
degree of cold ; and Mr. Braun, as well as Profeffor 
® /Epinus, 
