FUNDAMENTAL PROPERTIES OF MATTER. 29 



FIG. 13. 



with the only difference that they are more widely separated from 

 each other (Fig. 14). 



FIG. 14. 



Of the many proofs which we have of the fact that the latter 

 assumption is correct, one may be sufficient, viz., that the quantities 

 of vapor formed by volatile liquids at any certain temperature above 

 the boiling-point, in close vessels of the same size, are the same, no 

 matter whether the vessel was entirely empty or contains the vapors 

 of one, two, or more other substances. For instance : If we place 

 one cubic inch of water in a flask holding one cubic foot, from which 

 flask the air has been previously removed, and then heat the flask to 

 the boiling-point, the cubic inch of water will evaporate, filling the 

 vessel with steam. Upon now introducing into the flask a second and 



