a view to express also a part of the voltaic apparatus to which that name has never been applied, although it be identical with a pole in its relation to the current, the author proposes to employ the term electrode. The surfaces of the decomposing body, at which the positive current of electricity enters and passes out, are denominated respectively the eisode and the exode.

"Bodies which are decomposable by the electric current are called electrolytes; and when electro-chemically decomposed, they are said to be electrolyzed; the substances themselves which are evolved in such cases being called zetodes, and the terms zeteisode, and zetexode being applied, accordingly as the substances pass in one direction or the other."1

“I have made many endeavours to effect chemical decomposition by magneto-electricity, but unavailingly. as magneto-electricity can produce sparks," &c.

The instruments used to interpret the laws, and manifestations of physical science, are on many occasions the sources of error, as they are frequently of unexpected truths and discoveries, and both error and truth, may be elicited at the same time; in seeking a principle we may not find it; in the desire or attempt to establish a proposition we may lose it entirely, or we may, on the other hand, discover error, but which at the same moment may enunciate a new and permanent law.

Grove says, "I have now gone through the affections for which distinct names have been given in our received nomenclature, (namely, heat, light, electricity, magnetism chemical affinity, and motion,) that other forces may be discovered, differing as much from these as these differ from each other, is highly probable, and that when discovered, and their modes of action fully traced out, they will be found to be related inter se, and to these as they are to each other, I believe to be as far certain as certainty can be predicted of any future event."

2

1 Ibid., p. 294.

2 Grove, p. 90.

"Magnetism and electricity were believed by the highest authorities to stand in relation to cause and effect, i. e., electricity was regarded as the cause, and magnetism as the effect; and where magnets existed without any apparent electrical current to cause their magnetism, hypothetical currents were supposed for the purpose of carrying out the causative view; but magnetism may now be said with equal truth to be the cause of electricity, and electrical currents may be referred to hypothetical magnetic lines; again, if electricity causes magnetism, and magnetism causes electricity, why then electricity causes electricity, which becomes, so to speak, a reductio ad absurdum of the doctrine." This countenances the view adopted in this essay, which has been alluded to, namely, that electricity and magnetism "were one and the same thing," that is, in their original state of tension they are not only correlative, but identical, yet not inseparable, since their separability becomes quickly manifested by magnetism passing off, as a distinct element at right angles, and no "reductio ad absurdum" consequently occurs, since thenceforth they become the representative forces of two different and antagonist principles, namely, one, magnetism (the principle of aggregation, cohesion, and gravitation), and the other electricity, (the principle of segregation and motion.)

Magnetism, as was proved by the important discovery of Faraday, will produce electricity, but with this peculiarity -that in itself it is static; and, therefore, to produce a dynamic force, motion must be superadded to it; it is, in fact, directive and not motive, altering the direction of other forces, but not in strictness initiating them. It is difficult to convey a definite notion of the force of magnetism, and of the mode in which it affects other forces, &c., &c."1

Electricity proceeds to its destination, which is motion, but to arrive at it, it must part with magnetism, which is antagonistic of motion and heat; and as electricity is no sooner moved than this occurs, and magnetism rapidly passes off

1 Op. cit., p. 65.

through the influence of polarity at right angles from the current, and leaves electricity, which passes on to its proper destination; namely, motion, voltaic electricity, heat, chemical action, &c. Thus, as we have aimed to enforce, magnetism may be considered as the principle of aggregation, and cohesion, of homogeneity and rest; and electricity of segregation, namely, of heat and motion; the first represents "a static balanced force," the second heterogeneity, or so-called dynamical force." Nature gives us a remarkable difference in the character, or mode of the force eliminated by friction, accordingly as the bodies that impinge are homogeneous, or heterogeneous; if the former, heat alone is produced; if the latter, electricity. We find, indeed, instances given by authors of electricity resulting from the friction of homogeneous bodies; but, as I stated in my original lectures, I have not found such facts confirmed by my own experiments." 1

All conditions of vitality, are more or less motive or dynamical. Thus heat is one of the invariable concomitants of life, as it is also of electricity. Static electricity, i. e. electricity of tension retains, or has not yet parted with magnetism, voltaic electricity, or electricity of motion, has sent off magnetism, perhaps through the influence of polarization, and thus dynamical electricity is obtained; particularly as manifested in the voltaic current.

Grove says, 66 To many of the cases we have been considering, the term 'correlation' may be applied in a more strict accordance with its original sense; thus, with regard to the forces of electricity and magnetism in a dynamic state, we cannot electrize a substance without magnetizing it, we cannot magnetize it without electrizing it, each molecule, the instant it is affected by one of these forces, is affected by the other; but, in transverse directions, the forces are inseparable, and mutually dependent-correlative, but not identical." 2

1 Ibid., p. 20.

2 Op. cit., p. 96.