ELASTIC FORCES OF AQUEOUS VAPOUR. 603 
The tables show that this formula represents the observations 
pretty well; the greatest difference amounts to 13™™2; and 
corresponds to an error in the valuation of the temperature of 
eis. 
The experiments published in this memoir are therefore re- 
presented by three partial formulz of interpolation, the object 
of which is, to enable us to study the course of the observations. 
When I shall have completed my experiments at high tempera- 
tures, and compared the mercurial thermometers used in these 
experiments with an air thermometer, I intend to ascertain, 
whether it is possible to represent the whole of the observations 
by a single formula. 
At the end of this memoir will be found the Table of the 
elastic force of aqueous vapour calculated from the formule A 
and B for all degrees of temperature comprised between —32° 
and 100°. 
Very precise determinations of the elastic force of aqueous 
vapour for temperatures somewhat below 100° may be obtained, 
by observing the temperature at which water boils at different 
stations in ascending a high mountain. MM. Bravais and 
Peltier, at my request, made some observations of this nature 
on ascending the Faulhorn, during the summer of 1842. The 
note containing the details of these experiments is published in 
the Comptes Rendus de ? Académie, tome xviii. page 572. 
The numbers obtained by MM. Bravais and Peltier differ 
considerably from those deduced from my observations. It must 
be mentioned, that the thermometer used by those gentlemen was 
very irregular in its indications at the zero point; similar irre- 
gularities were consequently observable at the boiling-points. 
Another series of experiments was made by M. Marié, Pro- 
fessor of Natural Philosophy at the College of St. Etienne, in 
December 1843, in ascending Mont Pila. The details of these 
experiments were published in the Comptes Rendus de I’ Acadé- 
mie, tome xvill. page 252. 
I shall confine myself here to transcribing the results, and 
shall exhibit the elastic forces calculated for, the same tempera- 
tures by means of my formula. 
