576 On Evaporations 
and others have rejected it, and adopted that: 
which admits of distinct elastic vapours in the 
atmosphere at all temperatures, uncombined with 
either of the principal constituent gases 5» as 
being much more simple and easy'of explication 
than the other; though they do not remove the 
grand: objection to it, arising from atmospheric 
pressure. It has however’ been made to appear 
in these essays, I presume, that the objection 
to it from pressure, is itself founded upon an 
ungrounded hypothesis. 
Leaving the theory of evaporation for the 
present, we shall proceed to the experiments. 
The following positions have been established 
by others, and need therefore only to be men- 
- tioned here. 
4. Some fluids evaporate much more quickly 
than others, 
2, ‘The quantity evaporated is in direct pro- 
portion to the surface exposed, all other circum- 
stances‘alike. 
3. An increase of temperature in the liquid 
is attended with an increase of evaporation, not 
directly proportionable. 
4. Evaporation is greater where there is 
a stream of air than where'the air is stagnant. 
5. Evaporation from water is greater the less 
es i a eee 
a 
