of Edinhurgh^ Session 1883-84. 
599 
oxygen^ having given off its + E and now charged with - E, will 
combine with the kation + H. At the anode diffused hydrogen, 
after having received a positive charge from the metal, will 
combine with the anion - 0. So the results of the electrolytic 
decomposition of water are annihilated continually. Oxygen, 
charged negatively, migrates as anion from the cathode to the 
anode, then, neutralised, it is carried back to the cathode. Hydro- 
gen, charged and discharged, goes in the opposite direction. The 
work done by the electromotive force of the battery is not chemical 
decomposition, but it is this migration of the constituents of the 
fluids by which heat ought to be evolved. That heat, which is 
evolved by the migration of the ions, falls under the heat evolved 
by galvanic resistance, but the heat evolved by diffusion ought to 
be proportional to the intensity of the current. But before this 
stationary state of the current can be produced, electrolytic decom- 
position must go on till the required amount of gases is dissolved in 
the fluid, if there is not already from the beginning a sufficient 
quantity of one of the gases, viz., oxygen, of the atmosphere in solu- 
tion. Here the thermodynamic inferences come into play, which I 
have developed lately from the law of Carnot. They show that a 
limited quantity of the gases can be produced electrolytically even 
by very feeble electromotive forces, till a certain value of density of 
the dissolved gases corresponding to the value of the decomposing 
force has been reached. 
Out of these thermodynamic laws one can develop a complete 
mathematical theory of galvanic polarisation and its effects. As far 
as the accuracy of my measurements reaches, the facts appear to be 
in sufficient harmony with such a theory. 
2. On Cosmic Dust. By TAbbe Eenard. 
3. Esempio del metodo di dedurre una superficie da iina 
figura piana. By Professor Cremona. 
Scopo della presente piccolo comunicazione di mostrare con un 
asempio notevole, ed in connessione colla teoria conosciuta delle 
