Experiments upon Heat . 283 
equal, the intenfity of the communication is as the times 
inverfely. 
In thefe experiments the heat paffed through the furrounding 
medium into the bulb of the thermometer : in order to reverfe 
the experiment, and make the heat pafs out of the thermo- 
meter, I put the inftruments into boiling water, and let them 
remain therein till they had acquired the temperature of the 
water, that is to fay, till the mercury in the inclofed thermo- 
meters flood at 8o° ; and then, taking them out of the boiling 
water, I plunged them fuddenly into a mixture of water and 
pounded ice, and moving them about continually in this mix- 
ture, I obferved the times employed in cooling as follows* 
thermometer N° 
I. 
thermometer N c 
2. 
Surrounded by a Torricellian vacuum. 
Surrounded by air. 
Taken out of foiling water. 
and plunged 
Taken out of boiling watery 
and plunged 
into freezing water. 
into freezing water. 
Time elapfed. 
Heat loft. 
Time elapfed. 
Heat loft. 
Exp. N° 7. Exp. N° 8. 
Exp. N° g. Exp. N° 10. 
* 
8o° 
M. S. M. S. 
OW 
0 
M. S. M. S. 
- 
12 0 54 
70 
0 33 0 33 
70 
0 58 1 % 
60 
0 39 0 34 
60 
1 1 7 -118 
5 ° 
0 44 0 44 
50 
1 46 1 37 
40 
0 55 0 55 
40 
25 2 16 
3 ° 
1 17 1 18 
30 
3 H 3 10 
20 
1 57 1 57 
20 
5 42 5 59 
10 
3 44 3 4 ° 
10 
Not obferved. Not obferved, o 
40 IO Not obferved. 
O 
Total time of cooling from 8o° to io°. 
Total time of cooling from 8o° to 10°. 
M 
:. s. 
M. S. 
In Exp. N° 7.= 16 4 
In Exp. N° 9. “9 49 
In Exp. N° 8. — 16 
• 16 
In Exp. N q I 9 41 
Medium == 16 
> 10 
Medium — 9 45 
,Ppa 
By 
