Propagation of Heat in Fluids. 357 
embarrafs the water inits motions, or thofe (mucilages, &c.) 
which leffen its fluidity. 
The time required to heat the inftrument from 32° to 
200, when the bulb of the thermometer was furrounded with 
1. 2246 gr. of water and 192 gr. of flarch, was 1109” 
2, 2276 pr. of water and 192 gr. of eider-down, 949 
3. With water and 48 gr. or 3th of its bulk 
of eider-down é - - - 763 
4. With ftewed apples - - - 1096% 
5. With pure water - - - 597 
The ftarch was boiled with the water with which it was 
mixed, as was alfo the eider-down—the latter to free it from 
air, which adheres to it with great obftinacy. 
As Count Rumford fuppofes, and juftly, that there is a 
poffibility of error when the refults are determined by the 
extreme points freezing and boiling, owing to the flownefs 
of the procefs when the inftrument approaches the medium 
of the temperature in which it is placed, he thinks they may 
be got more accurately by taking the times occupied in heat- 
ing from 80° to 160. They were as follows ; 
with the rft 341! 
with the ad 269 
with the 3d 215 
with the 4th 335 
with pure water 172. 
The time the heat took to pafs out of the thermometer 
through the fame fubftances 
from 200° to 40° from 160° to 80?. 
through the 1ft ,. Peli et: ne » 468" 
PRAM eevee ST al BERD diye he QO 
ak ids + EROS F ee 
the 4th... 2) SUMOEO Te » 520 
Waters, oi whi eoge ; 245, Bag 
As the refults of thefe experiments prove that the propa- 
gation of heat in water is retarded, not only by thofe things 
which diminifh its fluidity, but alfo by thofe which, by me- 
Aa3 chanical 
