ON THE POWER OP FLUIDS TO CONDUCT HEAT. 



Experiment 3. 

 3. The Took an ale glafs of a conical figure, 2f inches in diameter 

 *r heated by anc * 3 inches deep ; filled it with water that had been ftanding 

 hot iron; in the room, and confequently of the temperature of the air 



cime e alfohot- nearI >"" Put the bulb of a ther mometer to the bottom of the 

 glafs, the fcale being out of the water : Then, having marked 

 the temperature, I put the red hot tip of a poker, half an 

 inch deep into the water, holding it there fteadily about half 

 a minute ; and as foon as it was withdrawn, I dipt the bulb of 

 a fenfible thermometer into the water about | inch, when it 

 rofe in a few feconds to 180*. 



TEMPERATURE 

 Time. at top. middle. bottom. 



Before the poker was immerfed 47* 



— 180° — 47 



5min. ]00 60° 47 \ 



20 70 60 49 



1 h. — 55 — ■ 52 



Thefe experiments all evidently agree in proving water to 

 have a proper conducting power, independent of any internal 

 motion. It furely will not be faid that any flight motion una- 

 voidably made at the beginning of an experiment, could con- 

 tinue with a powerful effect for upwards of an hour. How- 

 ever, to determine this matter, I made the two following 

 experiments. 



Experiment 4. 



Exp. 4. Co- Took the glafs tumbler of the firft experiment, and filled it 



loured water was h a ]f way with rain water, deeply tinged with archil ; then filled 



colourlefs water «* U P wrtn clear warm water, as related in the 2d experiment. 



retting upon it, The upper half was but juft perceptibly tinged by the procefs 



ture. U miX " an( * uniformly fo ; it remained for an hour not vifibly altered 



in this refpeel, though by frequently putting the bulb of a 



thermometer down to the middle, the colour at laft rofe in a 



fmall degree. 



(Air 



