7.0 
Steam Engine, 
Experiments on Spirit of Wine. 
By boiling a small portion of the spirit I used (about 
one cubic inch) in a phial, the thermometer stood at 179 
degrees at the commencement ; but by continuing the 
ebullition it acquired a greater heat. The reason is, the 
most evaporable part of the spirit flies off during the pro- 
cess of heating, and the rest being a weaker compound, 
requires a stronger heat. The true point of ebullition, I 
believe, was nearly 175 degrees. The force of the vapour 
from this spirit at the temperature of 212 degrees, I found 
both by an open syphon tube and one hermetically sealed 
with atmospheric air upon the mercurial column, as with 
ether, to be equal to 58 and an half inches of mercury. 
This rather exceeds the force of aqueous vapour at an 
equal distance from the boiling point ; but it is no more 
than may be attributed to unavoidable little errors in such 
experiments. In a barometer tube the spirituous vapour 
at 60 degrees, over the mercury, depresses the column 
about 1.4 or 1.5 inches; which is something less than 
the due proportion ; one cause of this may be the evapo- 
rability of spirits, which in operating on small quantities^ 
quickly dissipates part of their strength.” (Dalton.) 
The principles and manner of operation of the steam- 
engines of Savery, Newcomen and Cawley, and of Watt, 
may be understood from the following brief explanations 
and remarks, which I extract from Hornblower’s com- 
munication to Gregory. 2 Nich. 354. 
1. Savery’s engine.— Let there be a sucking pipe 
xvitii a valve opening upwards at the top, communicating 
with a close vessel of water, not more than thirty -three feet 
above the level of the reservoir, and the steam of boiling 
v/ater be thrown on the surface of the w^ater in the vessel, it 
will force it tq a height as much greater than 33 feet as 
