Text: This subject has been studied very carefully and for a great number of liquids by Professor Hittorff, of Münster, and Professor G Wiedemann, of Leipzig. They found that generally the velocities of the cation and the anion are different. Professor F. Kohlraush, of Würzburg, has brought to light the very important fact that in diluted solutions of salts, including hydrates of acids and hydrates of caustic alkalis, every ion under the influence of currents of the same density moves on with its own peculiar velocity, independently of other ions moving at the same time in the same or in opposite directions. Among the cations, hydrogen has the greatest velocity; the follow potassium, ammonium, silver, sodium, and afterward the bivalent atoms of barium, copper, strontium, calcium, magnesium, zinc; near the latter appears univalent lithium. Among the anions, hydroxyl (OH) is the first; then follow the other univalent atoms, iodine, bromine, cyanogen, chlorine, the compounds NO3, ClO3, and the bivalent halogens of sulphuric and carbonic acid; after these, fluorine and the halogen of acetic acid (C2H3O2). The only exception to this rule is the difference observed between the decomposition of univalent and bivalent compounds. Generally the velocity of any ion when separated from a bivalent mate is less than when separated from one or two univalent mates. It seems possible that the majority of molecules SO4H2 may be divided electrolytically into SO4 and H2; some of them, on the other hand, into SO4H and H. by the latter, some hydrogen would be carried backward, and therefore the velocity of the total amount might appear diminished. If both ions are moving, we shall find liberated at each electrode (1) that part of the corresponding ion which has been newly carried to that side: (2) another part which has been left by the opposite ion, with which it had been formerly combined. The total amount of chemical motion in every section of the conductor corresponds to the sum of positive electricity going forward and of negative electricity going backward. Thus established, Faraday's law tells us that through each section of an electroytic conductor we have always equivalent electrical and chemical motion. The same definite quantity of either positive or negative electricity moves always with each univalent ion, or with each unit of affinity of a multivalent ion, and accompanies it during all its motions through the interior of the electrolytic fluid. This quantity we may call the electric charge of the atom. I beg to remark that hitherto we have only spoken of phenomena. The motion of electricity can be observed and measured. Independently of this, the motion of the chemical constituents can also be measured. Equivalents of chemical elements and equivalent quantities of electricity are numbers which express real relations of natural objects and actions. That the equivalent relation of chemical elements depends on the pre-existence of atoms may be hypothetical; but we have not yet any other theory sufficiently developed which can explain all the facts of chemistry as simply and as consistently as the atomic theory developed in modern chemistry. Now, the most startling result of Faraday's law is perhaps this. If we accept the hypothesis that the elementary substances are composed of atoms, we cannot avoid concluding that electricity also, positive as well as negative, is divided into definite elementary portions, which behave like atoms of electricity. As long as it moves about in the electrolytic liquid, each ion remains united with its electric equivalent or equivalents. At the surface of the electrodes, decomposition can take place if there is sufficient electromotive force, and then the ions give off their electric charges and become electrically neutral. The same atom can be charged in different compounds with equivalents of positive or of negative electricity. Faraday pointed out sulfur as being an element which can act either as anion or as cation. It is an anion in sulfide of silver, a cation perhaps in strong sulfuric acid. Afterward he suspected that the deposition of sulfur from sulfuric acid might be a secondary result. The cation may be hydrogen, which combines with the oxygen of the acid and drives out the sulfur. But if this is the case, hydrogen recombined with oxygen to form water must retain its positive charge, and it is the sulfur which in our case must give off positive equivalents to the cathode. Therefore this sulfur of sulfuric acid must be charged with positive equivalents of electricity. When the positively charged atoms of hydrogen or any other cation are liberated from their combination and evolved as gas, the gas becomes electrically neutral; that is, according to the language of the dualistic theory, it contains equal quantities of positive and negative electricity. Either every single atom is electrically neutralized, or one atom, remaining positive, combines with another charge negatively. This latter assumption agrees with the inference from Avogadro's law, that the molecule of free hydrogen is really composed of two atoms. gg Now arises the question; are all these relations between electricity and chemical combination limited to that class of bodies which we know as electrolytes? In order to produce a current of sufficient strength to collect enough of the products of decomposition without producing too much heat in the electrolyte, the substance which we try to decompose ought not to offer too much resistance to the current. But this resistance may be very great, and the motion of the ions may be very slow--so slow, indeed, that we should need to allow it to go on for hundreds of years before we should be able to collect even traces of the products of decomposition. Nevertheless, all the essential attributes of the process of electrolysis could subsist. In fact we find the various degrees of conducting power in various liquids. For a great number of them, down to distilled water and pure alcohol, we can observe the passage of the current with a sensitive galvanometer. But if we turn to oil of turpentine, benzene, and similar substances, the galvanometer becomes silent. Nevertheless, these fluids also are not without a certain degree of conducting power. If you connect an electrified conductor with one of the electrodes of a cell filled with oil of turpentine, the other with the earth, you will find that the electricity of the conductor is discharged unmistakable more rapidly through the oil of turpentine than if you take it away and fill the cell only with air.

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