284 Sir Benjamin Thompson’s 
By thefe experiments it appears, that the conducting power 
of air is to that of the Torricellian vacuum as 944 t0 1644 
inverfely, or as 1000 to 603. 
To determine whether the fame law would hold good when 
the heated thermometers, Inftead of being plunged into freez- 
ing water, were fuffered to cool in the open air, I made the 
following experiments. The thermometers N° 1. and N° 2. 
being again heated in boiling water, as in the laft experiments, I 
took them out of the* water, and fufpended them in the middle 
of a large room, where the air (which appeared to be perfectly 
at reft, the windows and doors being all fliut) was warm to 
the 1 6th degree of Reaumur’s thermometer, and the times of 
cooling were obferved as follows. 
(Exp. N° 11.) 
Thermo?netcr N° I . 
Surrounded by a Torricellian vacuum. 
Heated to 8o°, and fufpended in the open 
air warm to 1 6°. 
(Exp. N w 12.) 
'Thermometer N° 2. 
Surrounded by air. 
Heated to 8o°, and fufpended in the opeti 
air warm to 1 6°. 
Time elapfed. Heat ioft. 
80 * 
M. S. 
Not obferved. 70 
I 24 60 
1 44 5 ° 
2 28 40 
4 *6 30 
jo 1 2 is total time employed 
in cooling from 70 ° to 30°. ( 
Time elapfed. Heatioft. 
So 0 
M. S. 
Not obferved. 70 
051 60 
1 5 5 ° 
1 34 40 
2 41 30 
6 1 1 zz total time employed 
in cooling from 70° to 30°. 
Here the difference in the conducing powers of air and of 
the Torricellian vacuum appears to be nearly the fame as in 
the foregoing experiments, being as 6 ~~ to 10IA inverfely, or 
$s 1000 to 605. I could not obferve the time of cooling from 
2 8q°' 
