PAPER BY DR. HERTZ. 211 



at pressure 4:Oo millimetres, and at temperature — 13.0° C, therefore 

 considerably below 0. Therefore there would have been no formation 

 of liquid water and therefore no stage for the formation of hail but 

 only sublimation of water from the vaporous into the solid condition. 

 We should then from the intersection of the Alpha line with the dotted 

 line 2.2 have followed directly the line of the Gamma system that might 

 have passed through this intersecting point. 



The question is not uninteresting — what dew point is the highest 

 that our mixture could have possessed in its initial condition as to 

 pressure and temperature, in order that the condensation of liquid 

 water, that is to say, the condensation at temperature above 0° C. should 

 be just avoided ? In order to answer this we follow the Alpha line to 

 the isotherm 0° and here find the dotted line 5.25. We therefore at 

 the highest could have had 5.25 grams of water per kilogram of air. 

 In order now to ascertain at what temperature the air would then have 

 been saturated under a pressure 750 millimetres, we slide along the 

 line 5.25 up to the isobar 750 and intersect it at the temperature 4.8° C, 

 and this is the desired maximum value of the dew point. 



Kiel, October, 1884. 



