It is exceedingly gratifying to me that a second edition of this book should be called for. But still more welcome is the change in the attitude of the educated world towards the old-time alchemists and their theories which has taken place during the past few years.

The theory of the origin of Alchemy put forward in Chapter I has led to considerable discussion; but whilst this theory has met with general acceptance, some of its earlier critics took it as implying far more than is actually the case. As a result of further research my conviction of its truth has become more fully confirmed, and in my recent work entitled Bygone Beliefs (Rider, 1920), under the title of “The Quest of the Philosopher’s Stone,” I have found it possible to adduce further evidence in this connection. At the same time, whilst I became increasingly convinced that the main alchemistic hypotheses were drawn from the domain of mystical theology and applied to physics and chemistry by way of analogy, it also became evident to me that the crude physiology of bygone ages and remnants of the old phallic faith formed a further and subsidiary source of alchemistic theory. I have barely, if at all, touched on this matter in the present work; the reader who is interested will find it dealt with in some detail in “The Phallic Element in Alchemical Doctrine” in my Bygone Beliefs.

In view of recent research in the domain of Radioactivity and the consequent advance in knowledge that has resulted since this book was first published, I have carefully considered the advisability of rewriting the whole of the last chapter, but came to the conclusion that the time for this was not yet ripe, and that, apart from a few minor emendations, the chapter had better remain very much as it originally stood. My reason for this course was that, whilst considerably more is known to-day, than was the case in 1911, concerning the very complex transmutations undergone spontaneously by the radioactive elements—knowledge helping further to elucidate the problem of the constitution of the so-called “elements” of the chemist—the problem really cognate to my subject, namely that of effecting a transmutation of one element into another at will, remains in almost the same state of indeterminateness as in 1911. In 1913, Sir William Ramsay[1] thought he had obtained evidence for the transmutation of hydrogen into helium by the action of the electric discharge, and Professors Collie and Patterson[2] thought they had obtained evidence of the transmutation of hydrogen into neon by similar means. But these observations (as well as Sir William Ramsay’s earlier transmutational experiments) failed to be satisfactorily confirmed;[3] and since the death of the latter, little, if anything, appears to have been done to settle the questions raised by his experiments. Reference must, however, be made to a very interesting investigation by Sir Ernest Rutherford on the “Collision of a-Particles with Light Atoms,”[4] from which it appears certain that when bombarded with the swiftly-moving a-particles given off by radium-C, the atoms of nitrogen may be disintegrated, one of the products being hydrogen. The other product is possibly helium,[5] though this has not been proved. In view of Rutherford’s results a further repetition of Ramsay’s experiments would certainly appear to be advisable.

As concerns the spontaneous transmutations undergone by the radioactive elements, the facts appear to indicate (or, at least, can be brought into some sort of order by supposing) the atom to consist of a central nucleus and an outer shell, as suggested by Sir Ernest Rutherford. The nucleus may be compared to the sun of a solar system. It is excessively small, but in it the mass of the atom is almost entirely concentrated. It is positively charged, the charge being neutralised by that of the free electrons which revolve like planets about it, and which by their orbits account for the volume of the atom. The atomic weight of the element depends upon the central sun; but the chemical properties of the element are determined by the number of electrons in the shell; this number is the same as that representing the position of the element in the periodic system. Radioactive change originates in the atomic nucleus. The expulsion of an a-particle therefrom decreases the atomic weight by 4 units, necessitates (since the a-particle carries two positive charges) the removal of two electrons from the shell in order to maintain electrical neutrality, and hence changes the chemical nature of the body, transmuting the element into one occupying a position two places to the left in the periodic system (for example, the change of radium into niton). But radioactivity sometimes results in the expulsion of a -particle from the nucleus. This results in the addition of an electron to the shell, and hence changes the chemical character of the element, transmuting it into one occupying a position one place to the right in the periodic system, but without altering its atomic weight. Consequently, the expulsion of one a- and two -particles from the nucleus, whilst decreasing the atomic weight of the element by 4, leaves the number of electrons in the shell, and thus the chemical properties of the element, unaltered. These remarkable conclusions are amply borne out by the facts, and the discovery of elements (called “isobares”) having the same atomic weight but different chemical properties, and of those (called “isotopes”) having identical chemical characters but different atomic weights, must be regarded as one of the most significant and important discoveries of recent years. Some further reference to this theory will be found in §§ 77 and 81: the reader who wishes to follow the matter further should consult the fourth edition of Professor Frederick Soddy’s The Interpretation of Radium (1920), and the two chapters on the subject in his Science and Life (1920), one of which is a popular exposition and the other a more technical one.

These advances in knowledge all point to the possibility of effecting transmutations at will, but so far attempts to achieve this, as I have already indicated, cannot be regarded as altogether satisfactory. Several methods of making gold, or rather elements chemically identical with gold, once the method of controlling radioactive change is discovered (as assuredly it will be) are suggested by Sir Ernest Rutherford’s theory of the nuclear atom. Thus, the expulsion of two a-particles from bismuth or one from thallium would yield the required result. Or lead could be converted into mercury by the expulsion of one a-particle, and this into thallium by the expulsion of one -particle, yielding gold by the further expulsion of an a-particle. But, as Professor Soddy remarks in his Science and Life just referred to, “if man ever achieves this further control over Nature, it is quite certain that the last thing he would want to do would be to turn lead or mercury into gold—for the sake of gold. The energy that would be liberated, if the control of these sub-atomic processes were as possible as is the control of ordinary chemical changes, such as combustion, would far exceed in importance and value the gold. Rather it would pay to transmute gold into silver or some base metal.”

In § 101 of the book I suggest that the question of the effect on the world of finance of the discovery of an inexpensive method of transmuting base metal into gold on a large scale is one that should appeal to a novelist specially gifted with imagination. Since the words were first written a work has appeared in which something approximating to what was suggested has been attempted and very admirably achieved. My reference is to Mr. H. G. Wells’s novel, The World Set Free, published in 1914.

In conclusion I should like to thank the very many reviewers who found so many good things to say concerning the first edition of this book. For kind assistance in reading the proofs of this edition my best thanks are due also and are hereby tendered to my wife, and my good friend Gerald Druce, Esq., M.Sc.

H. S. R.

191, Camden Road, London, N.W. 1.
October, 1921.