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For unless there were a continuous source of supply, the stock would evidently have long ago become exhausted. What perishes day by day must day by day be renewed, and the renewal is, in this case, apparently effected by the exorbitantly slow transformation of uranium. The grounds for this view are: First, that the two metals never occur separately, uranium always holding a percentage of radium; secondly, that this percentage has a constant value. Its invariability clearly results from the establishment of an equilibrium between production and waste. Radium is scarce, because it is quickly dissipated. It bears within itself the seeds of destruction. Solid in appearance, it is in reality more unstable than the thinnest air. Even the substantial preservation of its materials is open to doubt. In other words, there is some probability that many of the particles flung out from its disrupted atoms cease to be matter as ordinarily understood.

The principle of the conservation of mass was heretofore regarded as the corner-stone of the chemical edifice. It assumed matter to be indestructible, and indestructible it surely is by the time-honoured methods of the laboratory. Decomposition and recomposition, solution and precipitation, fractionation, distillation, calcination, leave mass exactly what it was before. Gravity is unalterable so long as the atom remains intact. But the break-up of the atom in radio-active processes lands us on a totally different plane of inquiry. Atoms are composed of 'electrons' or unit-particles of electricity, linked together by forces of tremendous power. When the infinitesimally small, though highly intricate, systems thus formed undergo collapse through some innate defect of stability, a readjustment ensues. Some of their component electrons issue freely into the ambient ether; others group themselves anew into atoms of less heavy metals; others again into helium-atoms. But the total resulting atomic weight must be less than the weight of the original, undecomposed atom, in consequence of the subtraction of escaped electrons. Whether or no electrons gravitate is a moot point. They possess inertia; yet appear to lie outside the domain of the great universal force. In shaking off atomic bonds they would then cease to gravitate, and mass would be, pro tanto, diminished.* On the contrary supposition, there should be a loss, not of absolute, but of measurable mass; for electrons, once set at large, are not easily recaptured.

These still obscure, though significant possibilities illustrate the radical change in the views of physicists brought to pass by

* E. Rutherford, 'Radio-Activity,' second edition, p: 336:

the investigation of radio-activity. Once more, as of old, the framework of nature has come to appear plastic. Once more we are confronted with the quintessential community of material things. We discern them as built up variously out of the same sub-elemental stuff, which, like the materia prima of the ancients, is subtilised to the verge of evanescence. What we call electrons, in short, our scientific ancestors designated 'protyle' conceived of as 'potentially all things, and actually nothing.' * Modern protyle has, however, been captured, and can be generated at will by the agency of electricity. No longer a metaphysical abstraction, it advances definite claims to a concrete if incomprehensible existence.

Elemental evolution, in its only cognisable form, inverts the course of organic evolution. For an ascent from homogeneity towards heterogeneity, it substitutes progress by degradation. Complex atoms are continually getting reduced to a more simple state through the shedding of their component electrons. Moreover, the shed electrons for the most part reconstitute themselves into systems, and enter upon independent atomic That is to say, there result, as the permanent products of radio-active change, a metal of inferior atomic weight to the metal partially decomposed, and a gas. Now the gas has been identified by its spectrum as helium, so named by Sir Norman Lockyer in 1869, because of its abundant presence near the

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Until 1895, when Sir William Ramsay made its hidingplace in clevite too hot to hold it, this singular substance was a mere cosmic acquaintance. The twelve years since elapsed, however, have sufficed to make its properties familiar. They are chiefly negative. It has no chemical affinities; a rogue element, it exists in isolation or imprisonment; it only slightly refracts light; it is electrically neutral; it remains obstinately aeriform at temperatures much below the boiling-point of hydrogen. Although of extreme terrestrial scarcity, its effusion is an unfailing concomitant of atomic decay, and from radium in particular, has been proved to go on without let or hindrance. The atoms of helium are thus framed under our eyes. We can watch an element in the making. But the process is usually far more leisurely. The evolution of metals is largely a matter of inference. It goes forward too slowly to be directly observable. To this rule there is, we admit, one exception. The degradation of uranium into [radium has become perceptible even within the brief span of recent experimental inquiry.

For the rest there is room and to spare for speculation. The

* Fowler's ' Novum Organum,' p. 339, note 13:

metals are very curiously interrelated, both in their qualities and in their distribution. Some occur in almost inseparable companionship. Among these cognate couples are silver and lead. In Mr. Donald Murray's words: 'A lead mine is a silver 'mine, and a silver mine is a lead mine all the world over, and yet the chemical attraction between silver and lead is slight, and the two metals are not sufficiently common to concur by chance. The inference was irresistible, and has been reached by others, that silver is a disintegration product of lead. And it is interesting to remember that lead, until superseded by mercury, was accounted in alchemistic theory the mother of 'metals.' Now the persuasion is gaining ground that the supplies of the various elements existing in the earth are regulated by the proportion between their rates of developement and dissolution. Elemental distribution does not show the extreme inequalities which would stamp it as the outcome of chance. The approximate constancy in the quantities present in all quarters of the globe of such rare metals as gold, platinum, thallium, indium, gallium, and so on, appears to intimate the working of a genetic law. It suggests that they are, in Professor Soddy's phrase, at once offspring and parent elements; † that they are derived from substances more highly elaborated; that they give rise, as they in turn spontaneously decompose, to others less complex, the relative speed of these ineffably slow alterations determining the amount of each product found in the earth at a given time. This remarkable hypothesis may be verified, according to Professor Soddy's anticipation, by the discovery of occluded helium in antique gold.

Thus physical science in the twentieth century has been strangely led to reoccupy some of the abandoned strongholds of the discredited horde of alchemists. We can see now that they were groping towards half-truths. And their instinct in selecting lead and mercury as initial forms of matter was so far right that both have atomic weights higher than those of gold and silver. But they erred hopelessly in pitting their feeble artifices against the imperturbable stability, measured on our time scale, of the created world. Irretrievable disaster and delusion could not but ensue from their attempts to control the uncontrollable, and to exploit inaccessible treasure stores. We know better. Radio-activity is the least manageable of natural processes. It will not be interfered with. We can only look on in wonder while it deploys its irresistible unknown forces. They reveal latent possibilities of mechanical power † Ibid. p. 151.

* Nature, vol. lxxiii. p. 125.

fabulous in amount, and within, it might be said, a hand's breadth of being industrially available; yet we are precluded from their employment. Base metals, we suspect with reason, are continually becoming ennobled ; but the gates of the half-seen Eldorado remain closed. Will they remain closed forever? That is an unread enigma. Should human ingenuity find means, in the future, to fling them wide, the newer alchemy will far outbid the promises of the old, and will cap its illusory performances with as yet unimaginable realities. Their accomplishment, however, will consist not in the lavish production of silver and gold, but in the subjugation of the untold energy accumulated at the beginning of the world in complex atomic systems. Nature here sits entrenched in her last fastness. The more sanguine among us anticipate its reduction. Others believe it to be impregnable. The forces that hold it will certainly not capitulate soon or easily. The siege must be prolonged and difficult; the issue is doubtful.

ART. III.-EGYPT: THE OLD PROBLEM AND

THE NEW.

1. England in Egypt. By VISCOUNT MILNER, G.C.B. Eleventh Edition. London, 1904.

2. The Making of Modern Egypt. By SIR AUCKLAND COLVIN, K.C.S.I. London, 1906.

3. Atrocities of Justice under British Rule in Egypt. By WILFRID SCAWEN BLUNT. London, 1906.

4. Correspondence respecting the Turco-Egyptian Frontier in the Sinai Peninsula. Egypt, No. 2 (1906).

5. Correspondence respecting the Attack on British Officers at Denshawai. Egypt, No. 3 (1906).

6. Further Paper respecting the Attack on British Officers at Denshawai. Egypt, No. 4 (1906).

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URING the past twelve months the affairs of Egypt have attracted more attention amongst the public in this country than has been the case of late years. The dispute between Turkey and Egypt as to the position of the frontier dividing the two countries, and the claim of the former to re-enter into possession of the Sinai Peninsula and establish herself in dangerous proximity to the Suez Canal, threatened at one moment to cause serious complications. After protracted diplomatic negotiations, a very stiff attitude, amounting almost to the presentation of an ultimatum, was required on the part of England before the Turkish pretensions were finally withdrawn and the demarcation of a satisfactory frontier assured. At the moment when the difference was at its height, the British public learnt with considerable alarm that symptoms of unrest had begun to manifest themselves amongst the Mohammedan population of Egypt and that it was necessary to reinforce the British garrison without delay. The troops sent in consequence of this decision had not been in the country more than three weeks when the Denshawai incident occurred. Five British officers in uniform, while shooting pigeons at a village near Tantah, the largest town in the Delta, were attacked by the villagers and very severely handled, one officer dying of his injuries and two others being badly hurt. It is not surprising that this sequence of events caused a general impression that the internal condition of affairs in Egypt was not so satisfactory as had been supposed or as might reasonably be expected after the labours and sacrifices of the last twenty-three years.

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