Isomerism is the term employed to represent another exceptional class of facts, observed by later chemists to interfere with the general rule, that analogy or similarity of composition implies analogy in form and external properties. Two or more compounds, formed of the same element, in the same relative proportions, and having, therefore, the same composition in 100 parts, are often found entirely distinct and unlike in all their properties. Such bodies are called Isomeric. "The discovery of Isomerism," says the same eminent chemist, "however unexpected, is entirely consistent with the atomic theory, of which it is merely a special case. Isomerism is of very frequent occurrence among organic compounds, owing, no doubt, to their unusually large atomic weights, since the numerous atoms of the elements afford much scope for isomeric modifications; and, doubtless, this principle plays an important part in the processes of organic life and growth, as well as in decay." [Footnote 124]
[Footnote 124: Ib. p. 43, 44.]
More remarkable than all of these exceptions to hitherto established laws is the discovery of the existence of simple elements under totally dissimilar forms. Thus sulphur exists under three distinct and incompatible forms, or modifications, called Allotropic. Carbon likewise in three; the diamond, which is crystallized in octohedrons, and is limpid and transparent; graphite, which is black, opaque, and crystallized in prisms; and common charcoal, lamp-black, etc., which is black and quite amorphous. Phosphorus has two allotropic forms: one crystallized, white and transparent, and easily set on fire; the other, deep reddish-brown, amorphous, and inflamed with much less ease. Each of these elementary bodies thus assumes appearances as dissimilar as if they were totally different bodies, possessed of a physical character quite unlike each other. Well may Professor Gregory, after this summary of the subject, add: "the occurrence of such marked differences in the properties of elementary bodies is very remarkable, and of great interest in reference to the molecular constitution of matter; but the subject has not yet been fully investigated." [Footnote 125]
[Footnote 125: Inorg. Chemistry, pp. 44, 45.]
The speculations of another very distinguished chemist, Professor Faraday, in this field of recent observation, are worthy of place in this collective testimony of modern science, to the imperfect acquaintance with the ultimate constitution of material substance attainable by any amount of study of its external properties or appearances. "There was a time," says this eminent philosopher, "and that not long ago, when it was held among the fundamental doctrines of chemistry, that the same body always manifested the same chemical qualities; excepting only such variations as might be due to the three conditions of solid, liquid, and gas. This was held to be a canon of chemical philosophy, as distinguished from alchemy; and a belief in the possibility of transmutation was held to be impossible, because at variance [{377}] with this fundamental tenet. But we are now conversant with many examples to the contrary; and, strange to say, no less than four of the non-metallic elements, namely, oxygen, sulphur, phosphoros, and carbon, are subject to this modification. The train of speculation which this contemplation awakens within us is extraordinary. If the condition of allotropism were alone confined to compound bodies, that is to say, to bodies made up of two or more elements, we might easily frame a plausible hypothesis to account for it; we might assume that some variation had taken place in the arrangements of their particles. But when a simple body, such as oxygen, is concerned, this kind of hypothesis is no longer open to us; we have only one kind of particle to deal with; and the theory of altered position is no longer applicable. In short, it does not seem possible to imagine a rational hypothesis to explain the condition of allotropism as regards simple bodies. We can only accept it as a fact, not to be doubted, and add the discovery to that long list of truths which start up in the field of every science, in opposition to our most cherished theories and long received convictions." [Footnote 126]
[Footnote 126: Lectures on Non-Metallic Elements, pp. 115, 116.]
Those persons who have resisted the evidence of Catholic revelation on the primâ facie ground that sound philosophy and a knowledge of the physical phenomena of nature are directly opposed to some of its doctrines, must begin, we should think, to feel their position a little less impregnable than it seemed before such sentiments as these were warranted by the actually established facts of modern science. With such evidence of its recent fruits, we may be well satisfied to watch with interest and congratulation the progress of philosophical inquiry conducted in such a spirit; not so much for our own sakes, to whom, indeed, no analogies afforded by any human science could add anything in the way of confirmation to what we have been taught by divine testimony, transmitted through the church of Christ to our remote age; but for the sake of the erring and the doubting among the intellectual minds of our fellow-countrymen; with the hope that their attention might be arrested and turned in the direction plainly enough indicated by such analogies. With one more extract, we must take leave of Professor Faraday's highly interesting volume; only begging as many of our readers as are interested in such pursuits to purchase it, and study it for themselves. After pointing out the difference between common and allotropic phosphorus, he continues: "We can scarcely imagine to ourselves a more complete opposition of qualities than is here presented in these two conditions of phosphorus; an opposition not limited by merely physical manifestations of density or crystallographic form, but recognizable through all the phases of solution, thermal demeanor, and physiological effect The metamorphosis has, in fact, been so complete, that we can only demonstrate the allotropical substance to be phosphorus, by reducing it to its original state, and subjecting it to ordinary tests. If the forces determining its constitution had been so balanced that the power of reduction were denied to us, then the substance we now call allotropic phosphorus must necessarily, according to the strictest propriety of logic, have been admitted to be not phosphorus, but some other body. It is impossible, rationally, to deny that such permanent incontrovertibility may not lie within the power of natural laws to effect. That we are not aware of such an example, cannot be accepted as a proof of its non-existence; and analogy, the guidance to which we refer when direct testimony fails, is in favor of the affirmative." [Footnote 127] From the great powers of analysis at the command of this distinguished physicist, directed as much by the courage as by the wisdom and the candid spirit of true philosophy, it is impossible to say [{378}] what further insight into the constitution of matter may not hereafter be obtained. Such an instance is surely of itself a full justification of our sanguine hopes for the future of science in its relation to what has been revealed by eternal and unchanging truth.
[Footnote 127: Lectures, etc., pp.42, 43.]
Rather by way of indication than of summary of the reflections suggested by these inquiries, we would ask, how is it that the almost illimitable extension of gross material elements should be accepted without hesitation, while the possibility of the spiritual and glorified body of the Lord existing, without division or multiplication of itself, in every Catholic tabernacle, and also in heaven, is regarded as so wildly impossible, and even monstrous a conception, as to be scouted at the bare mention of it? When philosophy expects us to believe that black, crumbling charcoal, and the hard, shining diamond, are one and the same simple substance, why should it be thought in the nature of things so incredible as at once to preclude all further examination of the evidence on which it rests, that the substance of the Child of Bethlehem, of the risen and ascended Lord, and of the most holy eucharist, are one and the same. We are far from saying that the mode of existence is the same in all these instances; we only claim for revelation what is conceded to science; that appearances should not be held, in limine, conclusive of the question, nor be allowed to outweigh or prejudice other evidence; for in every province of the universe of knowledge things are not what they seem. If what exists, or may exist, is to be limited by what human organs of sense can perceive, the boundaries of knowledge shrink into the narrowest compass: the eye and ear of an infant are enthroned as the judges of the constitution of nature; discovery and the progress of science are no more, or would never have been; mankind would yet be sunk in the imbecility of its primitive ignorance.
III.