[ *59 ] 
intenfe enough to be between the degrees of 181 
and ipi. 
When the natural cold was fo intenfe as to be at 
205, ProfeiTor Braun conje&ured, that it was of all 
others the mod: proper occafion to try the effects of 
artificial cold j not doubting, but that artificial cold 
would be increafed in proportion as the natural was 
more intenfe. Aquafortis, which was found by the 
thermometer to be 204 degrees cold, was the greated 
part of it frozen, the ice having the appearance of 
cryflals of nitre j which, however, immediately dif- 
folved in a fmall degree of heat. This aquafortis, 
which though frozen at the fides, was liquid in the 
middle, was poured upon pounded ice, in that pro- 
portion which was directed by Fahrenheit, the fird 
perfon who made artificial cold with fpirit of nitre. 
But before the profeffor made this experiment, he, 
by examination, found, that both the ice and aqua- 
fortis were of the temperature with the air, which 
was then 204. Upon the fird pouring, the mercury 
fell 20 degrees 5 this fpirit was poured off, and frefh 
put on, feveral times ; but it was poffible, by thefe 
means, to introduce no more than 30 degrees of 
cold; fo that the mercury in the thermometer fell 
no lower than 234. Since therefore Fahrenheit 
could not produce cold greater than that of 40 below 
the cypher of his thermometer, which correfponds 
with 210 of that employed by ProfeiTor Braun ; nor 
Reaumur, nor Mufchenbroek, who often repeated 
the fame experiment, our author was upon the point 
of giving up this purfuit; as confidering this as the 
greated degree to which artificial cold could be 
carried ; thinking it diffident honour to himfelf, 
to 
