On the Effect of Fluid Friction in drying Steam. 273 



conducted the galvanic current ; the same fluid was used and the 

 same vessel ; in fact everything was the same, except that in one 

 case decomposition accompanied the resistance, in the other it 

 did not ; and in the former the temperature did not rise to the 

 same degree as it did in the latter, and it was as much less as 

 the combination of the gases given off would have produced if 

 combined. 



I also placed two glass tubes, each containing the same quan- 

 tity of acidulated water, in one of which were the leaves of the 

 electrometer, in the other a platina wire offering the same resist- 

 ance as the fluid, in the circuit j so that the galvanic current 

 passed through both at the same time, and with the same result 

 as in the other experiments. 



(12.) I might bring forward many such experiments ; but 

 although they vary in details they are all the same in principle, 

 and prove the same fact. Enough I think has been said to esta- 

 blish the truth of my proposition. If admitted, some interesting 

 difficulties may be removed by its application ; for instance, it 

 explains why some compounds, such as alcohol, turpentine, &c., 

 do not g:ive out as much heat when burnt as their elements do 

 when separately ignited. It may also be made the means of 

 determining the amount of heat produced by the combination of 

 bodies, as the loss occasioned by their decomposition shows the 

 gain by theii' combination ; and in many other ways the prin- 

 ciple may be turned to advantage. For my present purpose, I 

 only ask that the simple fact I have endeavoured to prove be 

 allowed, viz. that decomposition of a compound body occasions as 

 much cold as the combination of its elements originally produced 

 heat. 



XL. Second Note 07i the Effect of Fluid Friction in drying 

 Steam which issues from a High-pressure Boiler into the open 

 Air. By Prof. W. Thomson*. 



IN the August Number of this Magazine, M. Clausius has 

 replied to a Note, published in the June Number, in which 

 I endeavoured to show that the objections he had made to my 

 reasoning regarding the condition of steam issuing from a high- 

 pressure boiler, were groundless. I cannot perceive that this 

 reply at all invalidates any of the statements made in my two 

 former communications f^ to which I refer the reader who desires 

 to ascertain what my views are, and to judge as to the correct- 

 ness of the reasoning by which they are supported. An analy- 

 tical investigation, according to the principles discovered by 

 Mr. Joule, of the thermo-dynamical circumstances of the rushing 



* Communicated by the Author. 

 - t Phil. Mag., vol. xxxvii. p. 387 (Nov. 1850), and vol i, 4th Ser.,p.474 

 (June 1851). 



