ELECTRONS.

Otago Daily Times, Issue 13859, 23 March 1907, Page 7

ELECTRONS.

SIR OLIVER LODGE ON THE NEW THEORY OF MATTER, A scientific correspondent of the London Morning Leader writes as follows: — Tho two great outstanding riddles that torture tho human intellect may bo said to bo the nature of life and tho nature of matter. It has loiij been :i favourite answer to the first, especially among quack medicine-mongers, who realise how comforting it is to a. certain class of minds to have one mystery explained by somestill more mysterious, that life is electricity; now tho physicists, in a much more sober and serious manner, are striving to answer tho second riddle with the 6tate°ment that matter is electricity. This idea is not exactly new. Its origin must be sought in experiments on the passage of electricity through spaces from- which most of the air had been exhausted, performed by Sir William Crookes and others a generation ago. But it,is only within tho last few years thai tho electric theory of mutter—the electronic theory, as it is usually called—has assumed anything like a coherent shape, and now Sii Oliver Lodge, himself a notable worker in this field, where, as he says, the condition of progress is the combination of experimental skill with advtuiccd mathematical theory, has given a lucid and convenient sununaiy of the present stato of knowledge, or speculation, regarding this -theory in a volume just published by George Bell and Sons, and entitled "Electrons," or the naturo and properties of negative electricity. DISEMBODIED ELECTRICITY. What is (tn electron? Every schoolboy who has been fortunate enough to attend a school which holds scienco classes, should bo familiar with plates, or spheres, or Ley den jars, charged" with electricity, and he has probably also been (aught that there aro two kinds of electricity, distinguished as positive and negative. To begin with, the electron was known as the charge or amount of negative electricity carricd on an atom of hydrogen when released from its union with oxygen when water was decomposed by. an electric curlent. _ Later exactly the same charge of electricity was found to exist under many other conditions, such us in tho rays produced by till! cleetrio current in a-' highly exhausted vacuum tube and in the ray's spontaneously shot off by radium. I/itci, again, it was recognised that this charge did not need to be carried on any material substance, but could exist free by itself— that-, in short, tho electron- was, in Sir Oliver Lodge's phrase, a- bit of " pure disembwlicd electricity." Not only, however, is it that; it- is also the smallest bit of electricity -that can exist. You may have two electrons or two millions, but you cannot havo half one. Tho electron is <t natural elcctricai unit-.

SIZE OF EIiECTRICr ATOMS. Tlio fact that electrons have mass and possess a separate existence entitles us in u sonse to say they are a form of mailer, and that therefore some matter is electrical; but it. is a long step to tho assertion that all matter is electrical, and' physicists are not yet prepared to tako that step. Various tentative) hypotheses, however, have been put forward to explain an atom of any material substance known to tho chemist—say hydrogen, as somo sort of combination of electrons and positive clcctricity. (Electrons or charges of positive electricity, by tho way, have not yet been discovered existing free or "disembodied.") Ihc most fully developed of these hypotheses is that the hydrogen atom consists of a presumably spherical mass or jelly of positive electricity containing electrons of Jicgativo electricity probably distributed. i n rings. _ Professor J. J. Thomson, of tho Cavendish Laboratory, Cambridge, who, with liis disciples, has taken a very largo share in tlio development of the electronic theory, has calculated that in the atom of hydrogen there aro somo 700 of these electrons. What their sizo must be may perhaps be imagined when it is remcmcrcdi that the linear dimension of an atom is supposed to be the ten-millionth of a millimetre, f.nd that they are about 100,000 times smaller. Tlie electrons do not fill all the space inside tho atom. Sir Oliver Lodgo lias calculated that if on electron ho looked upon as a speck one-hundredth r« an inch in diameter, like, for instance, the full stop that ends this sentence, then the space , availablo for the 700 electrons in tlio hydrogen atom is comparable to a liundrcd-feet cube; or, in other words, the ■ atom would he represented by a, church 160 ft long, 80ft broad', and 40ft high. IS IT A REVOLUTION? If it is asked whether this new electrical theory mil mako any difference in ordinary life, an answer—guarded because no ono itndWK what may happen—maj- be given in the negative. Even if the ultimate constituent atoms bo proved to consist of electricity, our food! will taste just the samo as at present, nor will our chairs cease to supjiort us or begin to give us electric shocks when wo sit on them. Though wo aro ignorant of the nature of electricity wo have learnt pretty well how to handle it and! utilise it for our convenience, awf the abstruse theories of physicists aro not likely to effect any immediate revolution in our methods of working clcctric tramways or in our views concerning the supply of elcctric power to .London. \ Some enthusiasts, however, aro proclaiming that tho acceptance of the electronic theory means tho ruin, and therefore the reconstruction, of tho atomic theory in chemistry. Those gentlemen, to isay the least, aro extremely rash. It is beside the question for them to argue that atom is a Greek word, meaning "not to ho divided," whereas on the electron (henry the atom can be divided into smaller part's, for very many words mean in actual uso something very different from what their derivation would imply. THEI ATOMIC THEORY. Tho atoms of tho different chemical elements are morelv the quantities with which tho chemist deals; he may say if he likes that they ore the smallest amounts in which each clement can exist, without losing its individuality, but beyond that it does not matter to him into how many fragments tbev can be rent. He knows that so many atoms of this clement- combined with so many atoms of that form a certain molecule, and tha', these molecules, or combinations of them, make up all tho tilings we touch and taste and sec. The atomic theory enables him to ascertain what relative proportions of different elements enter into combination with each other to form the numberless compounds with-ftTiieh he is acquainted, and being able to get that knowledge lie can be indifferent, so far as the validity of the atomic theory is concerned, to the actual constitution of the atoms, just as the bricklayer, wishing to build a wall of a given height and thickness, need not trouble about the composition of the bricks lie uses, so long as the knows their dimensions. lint the latest discovery in the electronic theory, which is hard to reconcile with earlier discoveries, seems ratljer to support than to undermine the atomic theory of the chemist : for a few months ago Prof. J. J. Thomson gave reasons for supposing that, instead of there being 700 electrons in a hydrogen atom, there is only one active electron in that atom, and that the numbers »f electrons in the atoms of other heavier elements are the same as tiie numbers liy which chemists express tue atomic weights of those elements. "if this turns out to be true, it must be more than a mere coincidence, and suggests that tho 'electronic theory has still something to learn from the atomic theory which wc are being asked to believe is moribund.