. ¢ he progress off al 
535 
EXPERIMENTAL ESSAYS 
On “the Constitution of mixed Gases ; 
on the Force of Steam or Vapour from 
Water and other Liquids in different tem- 
peratures, both in a@ Torricellian Vacuum 
and in Air; on EVAPORATION ; ; and on 
the Ba of Gases by Heat. 
BY JOHN DALTON. 
READ oct. 2, 16 anv 30, 1801. 
wee ft 
hilosophical knowledge is 
advanced by the discovery of new and important 
facts; but much more when those facts lead to the 
establishment of general laws. It is of impor- 
_ tance to understand that the descent of falling 
bodies is the same every where on the surface of 
the earth; but from that and some other parti- 
cular facts to infer the law of gravitation,, or 
that all matter attracts with a force decreasing as 
the square of the distance, is a much higher 
attainment in science... In the train, of experi- 
VOL, V. Fite a, 
