These facts of allotropism have some corollaries connected with them rather startling to us of the nineteenth century.  There may be other transmutations possible besides those of phosphorus and sulphur.  When Dr. Prout, in 1840, talked about azote and carbon being “formed” in the living system, it was looked upon as one of those freaks of fancy to which philosophers, like other men, are subject.  But when Professor Faraday, in 1851, says, at a meeting of the British Association, that “his hopes are in the direction of proving that bodies called simple were really compounds, and may be formed artificially as soon as we are masters of the laws influencing their combinations,”—­when he comes forward and says that he has tried experiments at transmutation, and means, if his life is spared, to try them again,—­how can we be surprised at the popular story of 1861, that Louis Napoleon has established a gold-factory and is glutting the mints of Europe with bullion of his own making?

And so with reference to the law of combinations.  The old maxim was, Corpora non agunt nisi soluta.  If two substances, a and b, are inclosed in a glass vessel, c, we do not expect the glass to change them, unless a or b or the compound a b has the power of dissolving the glass.  But if for a I take oxygen, for b hydrogen, and for c a piece of spongy platinum, I find the first two combine with the common signs of combustion and form water, the third in the mean time undergoing no perceptible change.  It has played the part of the unwedded priest, who marries a pair without taking a fee or having any further relation with the parties.  We call this catalysis, catalytic action, the action of presence, or by what learned name we choose.  Give what name to it we will, it is a manifestation of power which crosses our established laws of combination at a very open angle of intersection.  I think we may find an analogy for it in electrical induction, the disturbance of the equilibrium of the electricity of a body by the approach of a charged body to it, without interchange of electrical conditions between the two bodies.  But an analogy is not an explanation, and why a few drops of yeast should change a saccharine mixture to carbonic acid and alcohol,—­a little leaven leavening the whole lump,—­not by combining with it, but by setting a movement at work, we not only cannot explain, but the fact is such an exception to the recognized laws of combination that Liebig is unwilling to admit the new force at all to which Berzelius had given the name so generally accepted.

The phenomena of isomerism, or identity of composition and proportions of constituents with difference of qualities, and of isomorphism, or identity of form in crystals which have one element substituted for another, were equally surprises to science; and although the mechanism by which they are brought about can be to a certain extent explained by a reference to the hypothetical atoms of which the elements are constituted, yet this is only turning the difficulty into a fraction with an infinitesimal denominator and an infinite numerator.