and its Application to the Aqueous Vapour of the Atmosphere, 357 



(1) When the tube was filled with dry air, the drop of quick- 

 silver moved, during a rise of temperature from 12 0, 7 to 49°'2 

 a distance of 11*38 Paris inches. 



Fig. 3. 



(2) When some water was introduced into the globe K, the 

 quicksilver moved the same distance of 1 1*38 Paris inches during 

 a rise of temperature of only from 12°* 7 to 35°'3. 



If we calculate in the same manner as above the increase of 

 expansive force, we obtain — 



For dry air with a rise of temperature from 12 0, 7 to 

 49°«2 0-174 



For air and vapour together, with a rise of tempera- 

 ture from 12° '7 to 35 °- 3, separately, 



For air 0*103 



For vapour 0-082 



Together ] 0-185 



This result is somewhat greater than that obtained for dry air; 

 ground is therefore afforded for conjecturing that some vapour 

 must have passed from the globe K towards k; the quantity, 

 however, can only have been very small ; for when the vessel A A 

 contained water of constant temperature (13°) and cold and 

 warm water alternately were introduced into the vessel B B, in 

 order to move the quicksilver 7*80 Paris inches a rise of tempe- 

 rature was requisite as follows : — 



Before the above experiments . . . from 13°*5 to 47°'0 

 After the above experiments . . . from 13 0, 5 to 45°"8 



and afterwards, when the globe K had stood for two hours 

 together in water at a temperature from 35° to 40°, 



from 13°-5 to 44°-G. 



From the latter determination it is to be inferred that, not- 

 withstanding a considerable vapour-pressure was maintained for 

 so long a time in the globe K. yet not so much vapour had 

 passed into the globe k as would have been requisite for the 





