as deduced hi) Jiimselfand Dr. Suerman. 5^9 



In my experiments, though the same degree of pressure was 

 apphed to the different gases, they were driven from the one 

 gasometer to the other at very different rates, hydrogen much 

 quicker than nitrogen, air, or carbonic oxide, and these again 

 quicker than nitrous oxide or carbonic acid. Notwithstanding, 

 however, this difference of velocity, my results, as has been 

 shown, are relatively the same as those of Suerman, from 

 which we are entitled to infer that, provided the rate accord- 

 ing to which the gases rush by the wet thermometer does 

 not fall below a particular point, a variation of it does not 

 sensibly affect the observed depressions. 



But it is time to terminate these remarks, and I shall do so 

 with the following series of propositions : 



1. The results of Suerman are relatively the same as those 

 at which I have arrived. 



2. His absolute specific heats are greater than mine, partly 

 because of a difference between our formulas, and his attri- 

 buting to the latent heat of aqueous vapour a higher value 

 than I have done, but chiefly because the depressions obtained 

 by him were uniformly less than mine. 



3. His apparatus though very ingenious was complex, and 

 in consequence of the dimensions and shape of the tube con- 

 taining the thermometers could not give the maximum value 

 of /— ^'. My apparatus was simple, very easily operated with, 

 and as it gave greater depressions must have yielded results 

 closer to the truth. 



4. His apparatus was more perfect than mine in the cir- 

 cumstance of its having attached to it a manometer, by which 

 he was enabled to ascertain the actual pressure of the current 

 of air or gas. In mine there was no such provision, but the 

 augmentation of pressure was in every instance the same, and 

 must also, from the manner in which the gasometers were 

 connected, have been necessarily very small in amount. 



5. All results obtained by the method which we have em- 

 ployed must, theoretically speaking, be higher than the true, 

 as in consequence of the heat radiated from the sides of the 

 containing tube upon the wet thermometer, it is prevented 

 from reaching its extreme point of depression. 



6. Our researches completely refute the idea of the gases, 

 whether simple or compound, having under equal volumes 

 equal specific heats, and establish the very singular fact of 

 hydrogen having a specific heat very nearly once and a half 

 as high as that usually attributed to it. 



P.S. I should^not omit to mention that Suerman has inves- 

 tigated by the same method, and by means of a very simple 

 and admirable apparatus, the specific heat of atmospheric air 



