356 Count Rumford on the ~ 
an inch, and could contain, at the height of + of an saab 
above the bulb, 2468 grains of water. “4 
The bulb of the thermometer being furrounded by water, 
or by any other liquid, or mixture, the conduéting power of 
which was to be afcertained, a cylinder of cork + fomething 
lefs* m diameter than the brafs cylinder, about half an 
inch Jong, having a hole in its centre in which the tube of 
the thermometer paffed freely, was thruft down into the 
brafs cylinder nearly to the furface of the fubftance it con- 
tained, and made to reft on three projecting brafs points fixed 
to the neck of the copper bulb. The upper part of the tube 
was then filled with eider-down and clofed with a cork ftop- 
per g, the tube of the thermometer, which paffes through a 
fit hole in the middle of this ftopper, proje&ting upwards. 
The fcale from the point of freezing to that of boiling water 
is on that part of the tube which rifes above the ftopper, and 
is divided according to that of Fahrenheit. 
The thermometer being fixed in the tube as above de- 
{cribed, furrounded by the fubftance the conducting power of 
which was to be afcertained, the inftrument was placed im 
thawing ice, and kept there till the thermometer fell to 32°. 
It was then taken out and inftantly plunged into boiling 
water, and the conducting power of the fubftance under ex- 
periment was eftimated by the time required to make the 
heat pafs through it into the thermometer; the time being 
carefully noted when the liquid m the thermometer arrived 
at 40°, and alfo when it came to every 20th degree above 
Ht, 
A number of experiments were made with this inftrument, 
all of which tended to prove that the paflage of heat through 
water is much impeded, by mixing other fubftances with it, 
whether they be fuch (eider-down for inftance) as merely 
* Tf this cork had been made to fit clofe, yet fo as to move in the brafs 
cylinder, and its centre hole been well fitted to the glafs tube, the trouble 
of contriving and fixing pins to keep the bulb in its place might have been 
avoided. Epirt. 
embarrafs 
