PAPER BY PROF. BEZOLD. 259 



demonstrate the imperfections of this theory in his considerations on 

 this subject, followed the earlier method of treatment, and adopted the 

 volume as a basis. 



This is also quite justifiable so far as concerns the first estimates, and 

 I also recently have made the same application iu a popular lecture. 



But when one wishes to obtain exact formulae this method brings him 

 into difficulties. These arise from the fact that the capacity for heat of a 

 unit of volume, the so-called volume capacity, eveu without the consid- 

 eration of the intermixed vapor of water, is to a high degree affected 

 by pressure and temperature, so that no forms of approximation are al- 

 lowable. The cap icity for heat of the unit of mass of moist air, there- 

 fore its capacity for heat in the ordinary sense of the word, is entirely 

 independent of the above mentioned quantities and is also so little in- 

 fluenced by the contained water within the limits that occur in meteor- 

 ology that, as will later be more accurately shown, we can in the pres- 

 ent question simply consider it as constant. 



In order however not to lose the advantage that inures from the utili- 

 zation of existing tables, I have computed for different pressures and 

 successive degrees the quantity of aqueous vapor that is contained in a 

 kilogram of saturated moist air for such pressures and temperatures as 

 occur iu the atmosphere and have communicated the table thus formed 

 in an appendix to this paper (see page 287). 



This table not only facilitates very considerably the solution of the 

 questions that refer to the mixture of moist air, but it can also be ap- 

 plied with profit to many other investigations. After this preface the 

 problem itself is to be considered more closely, and to this end an appro- 

 priate notation is first to be introduced. 



Let there be 



wii and w?2i t;he quantities expressed in kilograms, of air to be mixed 

 together; 



f, and ^2, their temperatures; 



yx and 2/2, the quantities expressed in grams, of vapor actually con- 

 tained in a kilogram of moist air; 



y'x and y'^^ the corresponding values of contained moisture in a kilo- 

 gram of air at ti and U in the saturated condition ; 



Rx and R2, the accompanying values in per cent, of the relative hu- 

 midity. 



pi and p-z, the same quantities expressed as fractions of unity, that 

 is to say 



R\ -t R-i 



Px = — and p.2=~. 



^3? Hit y'ii ^3? and p3, the various values of the same above-named 

 quantities in the mixture, in so far as the limit 

 of saturation has not been exceeded, or at least 

 no water has been lost, that is to say, true sat- 

 uration exists. 



