ON THE POWER OP FLUIDS TO CONDUCT HfcAtY 



To determine whether hot and cold water being fuddenly 

 mixed, and agitated, the hot would afterwards rile to the top, 

 was the objed of 



Experiment 6. 



. 6. Hot Air in the room 50°. — About £ pint of water of 130° was 



fine mixed, did P oure( i mto a co ^ tumbler glafs, and immediately after as 



jot afterwards much water of 50°; the mixture was agitated for half a mi- 



feparate. nute ^ a ^^j ro( j . a ^ eJ . ^^ an i mmer f e d thermometer 



flood at 85°, both at, top and bottom ; it was then fet by in a 

 ftill place for examination. 



TEMPERATURE 



Time. at top. bottom, 



15 min. 77J* 77? 



30 73 72| 



45 68 67f 



1 h. — 64.8 64.6 



From all which From all thefe experiments it is evident, that water has a 

 deTtoSe^ro- P ro P er conducting power : In the laft experiment, if the par- 

 pcr conductor, tides of water during the agitation had not actually commu? 

 nicated their heat, the hot ones ought to have rifen to the 

 top, and the cold ones fubfided fo as to have made a material 

 difference in the temperature. It is, however, equally evi- 

 dent, that water is a bad conductor of heat, probably as it is 

 of electricity ; the defcent of the heat in the fecond experi- 

 ment is wonderfully flow ; a flight agitation for one fecond 

 would do as much to induce the equilibrium as flanding dill 

 one hour. In repeating the third experiment, in a wine glafs, 

 I have feverai times known water \ an inch deeper to differ 

 50 a in temperature from the incumbent water. 



We rauft conclude, therefore, that the quick circulation of 

 heat in water over a fire, &c. is owing principally to the in- 

 ternal motion excited by an alteration of fpecific gravity ; but 

 not jblely to that caufe as Count Rumford has inferred. 



If it be proved that water conducts heat, it will fcarcely 

 be necefTary to prove, that other fluids conduct it, and that 

 they communicate it one to another : — The two following 

 experiments fhew that mercury conducts it, and that water 

 and mercury reciprocally communicate it. 



Experiment 



