927. The general case (for it includes the former one (924.),) of acids and bases, may theoretically be stated in the following manner. Let _a_, fig. 79, be supposed to be a dry oxacid, and _b_ a dry base, in contact at _c_, and in electric communication at their extremities by plates of platina _pp_, and a platina wire _w_. If this acid and base were fluid, and combination took place at _c_, with an affinity ever so vigorous, and capable of originating an electric current, the current could not circulate in any important degree; because, according to the experimental results, neither _a_ nor _b_ could conduct without being decomposed, for they are either electrolytes or else insulators, under all circumstances, except to very feeble and unimportant currents (970. 986.). Now the affinities at _c_ are not such as tend to cause the _elements_ either of _a_ or _b_ to separate, but only such as would make the two bodies combine together as a whole; the point of action is, therefore, insulated, the action itself local (921. 947.), and no current can be formed. 928. If the acid and base be dissolved in water, then it is possible that a small portion of the electricity due to chemical action may be conducted by the water without decomposition (966. 984.); but the quantity will be so small as to be utterly disproportionate to that due to the equivalents of chemical force; will be merely incidental; and, as it does not involve the essential principles of the voltaic pile, it forms no part of the phenomena at present under investigation[A]. [A] It will I trust be fully understood, that in these investigations I am not professing to take an account of every small, incidental, or barely possible effect, dependent upon slight disturbances of the electric fluid during chemical action, but am seeking to distinguish and identify those actions on which the power of the voltaic battery essentially depends. 929. If for the oxacid a hydracid be substituted (927.),--as one analogous to the muriatic, for instance,--then the state of things changes altogether, and a current due to the chemical action of the acid on the base is possible. But now both the bodies act as electrolytes, for it is only one principle of each which combine mutually,--as, for instance, the chlorine with the metal,--and the hydrogen of the acid and the oxygen of the base are ready to traverse with the chlorine of the acid and the metal of the base in conformity with the current and according to the general principles already so fully laid down.