V 



1823.] Effect of Heat and Compression. 293 



528 millimetres ; the space dj double ef, is that 

 supposed to be occupied by the ether when it is 

 entirely reduced to vapour. 



The 528 millimetres were graduated on a sepa- 

 rate scale, which was applied when required to the 

 tube, as it was graduated towards the upper part. 



The apparatus, prepared as above described, 

 being closed at the extremities a, f, was heated 

 with the requisite precautions. At the moment in 

 which the ether was completely reduced to vapour, 

 the level b of the mercury rose to the point g, the 

 distance of which from the point a is 14 milli- 

 metres ; thus the column of air, tohich was 528 

 millimetres long, was reduced to 14 millimetres; 

 this indicates a pressure of 37 or 38 atmospheres. 

 This experiment three times repeated gave each time 

 the same result. 



Ether is, therefore, susceptible of being reduced 

 to vapour in a space less than double that of its 

 original volume, and in this state of vapour, it 

 exerts a pressure of 37 or 38 atmospheres in the 

 tube which contains it. 



Exper. 2. — Alcohol of specific gravity 0*817 was 

 substituted for ether in the apparatus above de- 

 scribed by opening the ends^' and a ; the alcohol 

 occupied the space f e, that is to say, one-third 

 of that supposed to be necessary for the total 

 conversion of the alcohol into vapour, 

 cury occupied the space b' b c d e' , and 

 small tube, when, by inclining the apparatus, the 

 level e' was sunk to d. The length of the column 

 of air a b' was 476 millimetres. After the extre- 

 mities a and f were closed by the blowpipe, the 

 apparatus was exposed to heat with the same pre- 

 cautions as observed with respect to the ether. 

 At the moment in which the alcohol was totally 

 reduced to vapour, the level b' of the mercury 

 rose to the point g' ', that is to say, to four milli- 

 metres from the point a. Thus the column of air, 

 of 476 millimetres in length, was reduced to four 

 millimetres, which indicates a pressure of 1 19 

 atmospheres. 



Alcohol may, therefore, be totally reduced to 

 space rather less than three times that of its original volume ; 

 and at this degree of expansion, it exerts a pressure of 119 atmo- 

 spheres on the tube which contains it. 



The extremities a and^ were a little drawn out, in order that 

 they might be more readily closed by the blowpipe ; and the 

 capacity of these parts of the tube was ascertained by introduc- 



The mer- 

 filled the 



■a 



vapour in a 



