251 



ployed in alternation with plates of a single metal, the alkaline solu- 

 tion received the electricity from the metal, and the acid transmitted 

 it to the metal. So in the simplest case of electrical action, the alkali, 

 receiving electricity from the metal, would, on being separated from 

 it, appear positive, and of course be repelled by positively electrified 

 surfaces, and attracted by negatively electrified surfaces ; the acid, 

 acquiring the contrary electricity, following the contrary order. 



Several phenomena accord with this idea. Sulphur separated from 

 its contact with a metal is positive ; and, in like manner, sulphur 

 separated from sulphuric acid by electricity is attracted by the nega- 

 tive surface. And again, hydrogenated sulphuretted alkalies, being 

 composed of three substances, all positive, are so very active in vol- 

 taic combinations as, in certain cases, to overpower the energies of 

 the metals. 



Mr. Davy then considers the relation between the electrical energy 

 of bodies and their chemical aifinities ; and observes, that all the sub- 

 stances that combine chemically, exhibit, so far as is known, opposite 

 electric states ; and that, in the various experiments of decomposition 

 by electricity, the natural electrical energies of the constituent parts 

 of the compounds acted on are, as it were, overpowered by the arti- 

 ficial electricities : so that it is probable that chemical affinity depends 

 upon the different electrical energies of the acting bodies. 



And upon this supposition, particles possessed of opposite electrical 

 states and freedom of motion will enter into combination. When two 

 bodies possessed of the same state act upon a third body possessed of 

 the opposite state, the substance possessing the weakest energy will 

 be repelled. In other cases there may be such a balance of attractive 

 and repellent powers as to produce triple compounds, or even more 

 complicated combinations. It will also be easy to explain the in- 

 fluence of the masses of bodies upon their affinities ; for the combined 

 effect of many particles possessing a feeble electrical energy may be 

 conceived equal, or even superior, to the effect of a few particles 

 possessing a strong electrical energy ; and, accordingly, we find that 

 concentrated alkalies resist the transmission of acids more powerfully 

 than weak ones. 



As the strength of the electricity diminishes from the points to the 

 middle of the water, a measure of the artificial energies may be ob- 

 tained by the place where the compounds begin to be decomposed. 

 Thus sulphate of barytes requires intermediate contact with the 

 wires; and when 150 pieces of plates were used with a circuit of 

 water of ten inches, sulphate of potash was not decomposed at four 

 inches from the positive wire ; but when brought within two inches, 

 its alkali was strongly repelled. 



As heat and light are the consequences of a restoration of the equi- 

 librium between bodies in a high state of opposite electricities, so are 

 they also the result of all intense chemical action; and again, as when 

 large quantities of electricity of low intensity act, heat is produced 

 without light, so in low combinations the temperature only is in- 

 creased. The effect of heat in promoting chemical action seems not 



