78 
THE NATURE AND 
[sect. II. 
lowing table, they serve here to indicate that the observed numbers are probably 
too low for the true ones. 1 
111. Experiments on the Force of the Vapour of Sulphuret of Carbon, 
by M. Cagniard de la Tour. 
Volume in liquid state 8 parts. 
Volume in the state of vapour 20 parts. 
Degrees of heat by 
Force. 
Difference. 
Force of vapour by 
Fahrenheit. 
formula below. 
Atmospheres. 
Atmospheres. 
Atmospheres. 
212° 
4-2 
4-03 
2345 
5-5 
1-3 
5-3 
257 
7-9 
2-4 
6-8 
279-5 
10-0 
2-1 
8-7 
302 
130 
30 
11-0 
324-5 
16-5 
3-5 
13-8 
347 
20 2 
37 
17-3 
369-5 
24-2 
40 
21-3 
392 
28-8 
4-6 
26-2 
414-5 
33-6 
4-8 
31-9 
447 
40-2 
6-6 
42-0 
469-5 
47-5 
7-3 
503 
492 
57-2 
9-7 
60-2 
514-5 
66-5 r _ f . . 
_ Lvapour. 
89-2 1 
9-3 
71-4 
537 
11-3 
84-5 
559-5 
11-4 
99-5 
572 
98-9 
9-7 
594-5 
1143 
15-4 
617 
1296 
15-3 
628-25 
133-5 
3-9 
The irregularities in all M. Cagniard de la Tour’s experiments would be in part 
occasioned by the expansion of the tubes under such high pressures and tem 
peratures ; hence, to attempt a minute comparison would only show a want of 
attention to physical effects too common in such inquiries. The usual practice of 
attempting to supply want of observation by minute calculations, is one of the 
great defects of the present mode of scientific inquiry, as applied to improve the 
scientific arts. 
112. The forces of various other substances have been tried, but not with 
much attention to the selection of such as are adapted for the acting vapours in an 
engine ; as, for that purpose, one should be chosen which affords the highest power 
1 The rule in logarithms for sulphuret of carbon, by which the calculated numbers in these 
tables were found, is 
log. /=6 ^log. (t + 280) — 2-34488^) 
to the point where the liquid becomes wholly vapour.