CONCLUDING REMARKS. 163 



chemical action is produced. If we take another substance, 

 say a metal, all these forces except the last are developed ; 

 and although we can scarcely apply the term chemical action 

 to a substance hitherto undecomposed, and which, under the 

 circumstances we are considering, enters into no new combi- 

 nation, yet a metal undergoes that species of polarisation 

 which, as far as we can judge, is the first step towards chemical 

 action, and which, if the substance were decomposable, would 

 resolve it into its elements. Perhaps, indeed, some hitherto 

 undiscovered chemical action is produced in substances which 

 we regard as undecomposable : there are experiments, to 

 some of which I have alluded, which tend to show that metals 

 which have been electrised are permanently changed in their 

 molecular constitution. Oxygen, we have seen, is changed by 

 the electric spark into ozone, and phosphorus into allotropic 

 phosphorus, both which changes were for a long time unknown 

 to those familiar with electrical science. 



Thus, with some substances, when one mode of force is 

 produced all the others are simultaneously developed. With 

 other substances, probably with all matter, some of the other 

 forces are developed, whenever one is excited, and all may be 

 so were the matter in a suitable condition for their develop- 

 ment, or our means of detecting them sufficiently delicate. 



This simultaneous production of several different forces 

 seems at first sight to be irreconcilable with their mutual 

 and necessary dependence, and it certainly presents a formid- 

 able experimental difficulty in the way of establishing their 

 equivalent relations ; but when examined closely, it is not in 

 fact inconsistent with the views we have been considering, but 

 is indeed a strong argument in favour of the theory which 

 regards them as modes of motion. 



Let us select one or two cases in which this form of objec- 

 tion may be prominently put forward. A voltaic battery 

 decomposing water in a voltameter, while the same current is 

 employed at the same time to make an electro-magnet, gives 

 nevertheless in the voltameter an equivalent of gas, or de- 

 composes an equivalent of an electrolyte for each equivalent 

 of chemical decomposition in the battery cells, and will give 

 the same ratios if the electro-magnet be removed. Here, at 



M 2 



