29 
Steam Engine* 
temperature, and they are immediately converted into 
gases ; or, their temperature remaining the same, diminish 
the weight of the atmosphere ; and the caloric, which 
they naturally contain, exerts its repulsive tendency with 
equal effect, and they are in like manner converted into 
gases. These facts are best shown by the following ex- 
periments on ether : 
1. Ether, at the temperature of 104<», exists in the state 
of a gas. This may be shown by filling a jar with water 
of this temperature, and inverting it in a vessel of the same. 
Then introduce a little ether, by means of a small glass 
tube closed atone end. The ether will rise to the top of 
the jar, and, in its ascent, will be changed into gas, filling 
the whole jar with a transparent invisible elastic fluid. 
On permitting the water to cool, the ethereal gas is con- 
densed, and the inverted jar again becomes filled with 
water. 
2. Ether is changed into gas by diminishing the weight 
of the atmosphere. Into a glass tube, about six inches 
long, and half an inch in diameter, put a tea-spoonful of 
ether, and fill up the tube with water ; then, pressing the 
thumb on the open end of the tube, place it, inverted, in 
a jar of water. Let the whole be set under the receiver of 
an air pump, and the air exhausted. The ether will be 
changed into gas, which will expel the water entirely from 
the tube. On re-admitting the air into the receiver, the 
^as is again condensed into a liquid form. 
IV. On the contrary^ by considerably increasing the 
pressure^ water may be heated to above 400® Fahrenheit^ 
without being changed into vapour* This experiment re- 
quires, for its performance, a strong iron vessel, called a 
Papin’s digestor, which is an iron boiler holding half 
* The lines marked with brackets, I have substituted for Dr. 
Henry’s text, which refers to figures that I cannot give. T, C. 
