of Electrical and Chemical Changes. 197 



ing to transfer baryta from the positive to the negative pole, 

 the negative pole being plunged in sulphuric acid, or sulphuric 

 acid to the positive pole, the negative being plunged in a so- 

 lution of baryta, the re-agents were neutralized, and formed 

 insoluble precipitates at the point of union of the menstrua ; 

 and no baryta reached the negative, and no sulphuric acid the 

 positive pole. 



With muriatic acid and salts of silver the case was the same. 

 And when acids and alkalies, forming soluble compounds, 

 were used in similar experiments, a great length of time was 

 required, proportional in some measure to their masses, be- 

 fore a particle of acid reached the positive, or of alkali the 

 neo-ative pole ; and the result was not destroyed till after the 

 int'ermediate combination had taken place to a considerable 

 extent ; proving the phaenomena of continued decompositions 

 and recompositions, and showing that the electrical and che- 

 mical phnenomena are of the same order, and produced by the 

 same cause. 



In theBakerian Lecture for 1806, I proposed the electrical 

 powers, or the forces required to disunite the elements of 

 bodies, as a test or measure of the intensity of chemical union. 

 By the use of the multiplier it would be now easy to apply 

 this test; and accurate researches on the connexion of what 

 may be called the electro-dynamic relations of bodies to their 

 combining masses or proportional numbers, will be the first 

 step towards fixing chemistry on the permanent foundation of 

 the mathematical sciences. 



I could enter into some other general views of the pure 

 scientific relations of this subject, and its connexion with 

 thermo-electricity and the phaenomena of cohesion ; but having 

 already taken up so much of the time of the Society, I shall 

 defer what I have to say on these subjects to another occasion, 

 and I shall conclude with a few practical observations. 



A frreat variety of experiments made in different parts of 

 the world has proved the full efficacy of the electro-chemical 

 means of preserving metals, particularly the copper sheathing 

 of ships ; but a hope I had once indulged, that the peculiar 

 electrical state would prevent the adhesion of weeds or insects 

 has not been realized ; protected ships have often indeed re- 

 turned after long voyages perfectly bright*, and cleaner than 

 unprotected ships, yet this is not always the case; and though 

 the -iohule of the copper may be preserved from chemical solu- 

 tion in steam vessels by these jneans, yet they must be adopted 

 in common ships only, so as to preserve a portion, — so ap- 

 • The Carnebica Castle. 



plied 



