578 On Evaporation. 
be kept just at the point 6f ebullition. In this 
state the vessel and water were weighed true to 
a grain, and the instant of time noted by a watch ; 
then kept as above at 212° for ten minutes.or 
more and again weighed: and the loss of water 
by evaporation, per minute, was thus ascertained. 
The experiments were repeated several. times 
in the same as well as in different circumstances ; 
and the results in no instance differed materially 
when obtained in the same circumstances. 
The least evaporation per minute was 30 
grains: this was when the fire, or lamp, was in 
the middle of a room, the doors and windows 
shut, and the air calm, 
The next degree was 35 grains per minute or 
thereabouts: this was when the evaporating 
vessel was over a small fire in the usual fire. 
place; there being a moderate draught of air, 
and the room close. 
A brisker fire, causing a stronger current of 
air up the chimney, gave from 35 to 40 grains 
per minute. 
When the windows of the room were open, 
and a strong wind prevailed, the draught over 
the fire was proportionally increased, and the 
evaporation was from 40 to 45 grains per 
minute. 
> AE 62 RES ty ote sees 
