OF STEAM ARTSTN«; rnOI\r TIOTLTNT! SALT SOLUTIONS. 7 



]")ors in the seoonrl column of the talile may have indicaterl, therefore, 

 not so miK'li the temjierature of the natural steam as that of the sur- 

 rounding walls and of tlie steam superlieated l)y them. Strange to 

 say, Magnus seem:^ to have heen aware of this element of uncertainty 

 in his results, and yet to have disregarded it. He writes : — " Soviel 

 ist indess durch diese Versuche bewiesen, dass die Dämpfe, welche 

 auskochenden Salzlösungen aufsteigen, eine höhere Temperatur als 

 100° lial^en, und eine um so höhere, je höher die Temperatur der 

 kochenden Lösung ist. Dass sie aber dieselbe Temperatur wie diese 

 Di)Suno' haben, ist mir nicht 2:elun2:en nachzuweisen, und ich zweifle 

 dass diess möglich sein wird. Denn wenn die Wände des Dampf- 

 raumes auf der Temperatur der kochenden Lösung erhalten werden, 

 so ist man, wie schon oben bemerkt, nicht sicher, dass nicht die 

 Erwärmung von diesen Wänden hervorgebracht ist, haben dagegen 

 die Wände eine niedrigere Temperatur, so wird aucli die Temperatur 

 des Thermometers niedriofer ausfallen." 



What then, it may pertinently l)e asked, is the value of his ex- 

 })erimental results? It seems to me that Magnus erred in having the 

 Avails of his vessel of a highly conducting material, so that the thermo- 

 meter would indicate the temperature of these walls, derived as it was 

 from the solution and even from the heat of the lamp, and then to 

 regard the temparature observed as ])eiHg that of the steam. In fact, 

 it can be readilv sliown that l)y keeping the walls of a vessel at a 

 temperature Idgher tlian 100°, say at 110°, the steam issuing from 

 water itself indicates a temperature almost equal to that of the walls. 



The results obtained by IVIagnus, which have been regarded as 

 tlie most weighty and cc^nclusivc experimental proof of the view that 

 the steam arisino- from a boilin"" salt solution has the same or nearlv 

 the same temperature as the latter, thus appear to me t«^ be valueless, 

 and the same remark applies to Faraday's later experiments already 



