ELECTRO-CHEMISTRY, GENERAL. The branch of general chemistry that deals with chem ical changes producing. or caused by, electrical energy. The growing industrial applications of electro-chemistry are rendering the science itself more and more important every year. Another title of electro-ehemistry to general interest con sists in the fact that the phenomena it deals with have long formed a bond between two great branches of human knowledge—physics and chemistry—the science of the various forms of energy and the science of the various kinds of matter. The bond may become even more in timate if the comparatively recent hypothesis, according to which electricity itself is a subtle form of matter, turns out to be in agreement with facts. This hypothesis is briefly as follows: consists of two chemical elements whose atoms, termed 'electrons.' have exeeedingly small (perhaps zero) relative weights: the atoms of positive electricity, or 'positive electrons; may be denoted by the symbol e: the atoms of nega tive (deetrieity, or 'negative electrons,' may be denoted by the symbol e: like the atoms of hydrogen. electrons of either kind are univalent ; so that, for instance. an atom of hydrogen when in the ionic state (i.e. when charged with elec tricity) is combined with a single positive elee tron. forming the compound II Ep, while an atom 01 eoxygen in that state forms the com pound (just as water is not thus combined with the atoms of other ele ments, electrons may possibly form neutral mole cules a, The made up of such node cities may have appreciably no weight. may be a non-eonduetor, and may be capable of elec tric polarization: and it is worthy of notice that these are precisely the properties attributed to the lumi»iferous ether. 1\liile this hypothesis render, Faraday's law (see ELECTRICITY) a spe cial ease of Dalton', law of multiple proportions, and may certainly be helpful in fixing on the mind a definite image of the mecha nism of electrical processes, it can hardly be said yet to rest on a sufficient foundation. Whether
it should be accepted or not, will have to be de cided on the principle expressed. some years ago, by PeeinearC•: "It is nonsense to ask of a theory. 'Is it true or false?' The question can only be, 'Is it fruitful or not?"' At any rate, the electron hypothesis must not be allowed to confuse our conception of etre- tricot energy and its relations to other forms of energy. The term energy, when properly used, designates the cause of any change that is actu ally taking place, or that is capable of taking place, in a given system. Thus We may speak of the energy of a falling body, and even of a body suspended at a certain height from the earth's surface; for such a body, if released, zrou/d fall to the earth. Similarly, we may speak of 'elec trical energy' whenever a transport of electricity from one point to another is possible in a given system. Energy of every known form can be re solved into two factors—a 'capacity factor' and an 'intensity factor.' In the case of electrical energy, the capacity factor is generally known as 'quantity of electricity,' the intensity factor as 'potential-difference.' Just as in the case of a suspended body the amount of gravitation energy is the greater, the greater the mass of the body and the greater the difference of level between the body and the earth's surface, so in the case of possible flow of electricity, the amount of electrical energy is the greater, the greater the quantity of electricity and the greater the differ ence of potential between the two given points. Whatever be the ultimate nature of a mass of matter, gravitation energy is still a form of energy. Similarly, whatever be the ultimate nature of a quantity of elect•ieity—whether elec t•icity be a kind of matter or not—electrical energy is still a form of energy. capable of being transformed into kinetic energy. chemical energy, etc.