A RECENT DISCOVERY.

New Zealand Herald, Volume XXXVIII, Issue 11692, 29 June 1901, Page 2 (Supplement)

A RECENT DISCOVERY.

THE NATURE ,OP ELECTRICITY. The busy man; lias had no more tantalising 'v; experience than that of witnessing the won. f derful modern achievements of electricity- % all around him' without being able to get &■ •' ghost of an idea of the agent at Work. ; Coming across an electrical engineer, or aj j telegraph expert, he may seek for enlighten-i ment, only to j find himself more darkly be-i fogged hi technicalities about potential vol-' tage, magnetic induction, and the like, or to! • be met with the frank confession from thai - expert that hitherto the highest specialists ; in electrical science have been gro ping about? . for a conception of the nature <>i electricity. almost as blindly as the uninitiated theni4 selves. But during tho last few years,: while the practical electrician Las been 'tap-{ ping' Niagara and opening up electric trams; : by the thousand miles, the scientific electri-j. ; cian in his laboratory has been interrogate' ing Nature with an energy and persistence'- ; quite as remarkable. The result is that aI " very clear and simple account can now be ; given of the essential nature oi' electricity 1 ; : and of its relation to matter, although the mastery of its . details will still demand » . . specially trained intelligence. . _ V ; | The starting point of tho new conception;; 7 of electricity is that, like matter, it is atomic in its structure. Everyone knows that thai-' great progress of the science of chemistry! has been due to the discovery that matter is: / made up of atoms, whose endless variety of, arrangements into different molecules givea. us our infinite variety of forms of matter,, ;: from bullet to brain stuff, from compost heap.. ; to perfume of flower, from crystal of salt, ; to glowing, nebula, in the depths of space.,; Tho properties of a pure substance are. d<}4 1 , termined entirely by those of a single nioli" cule of it, and these depend only on the ' •••:' atoms centering into its. composition and ! : their arrangement within it. Now, it is one of the greatest discoveries' hi modern' 'iy times that the atoms in the molecule are fastened together by means of electricity.', But further, for the fastening of an atom . • of matter to others there may be required one, two, three, or any number up to seven, . of atoms of electricity, which are called >. electrons. For example, an atom of hydrogen requires an electron, and only one, to fix it in its place in any molecule. An atom of oxygen requires two, and sometimes four, an atom of iron sometimes two and sometimes six. But while there are about 70 different sorte of atoms known to the chemist, there are only two sorts"of electron known to the electrician, and thesa make ; up the two sorts of electricity called positive and negative.' . ' :v' : ;r i.:< The atoms! of matter attract one another' except when actually in collision, whence comes to pass the cohesion of solid bodies,,' and also the phenomena of gravitation. Now; the forces of cohesion have a very limited) 1 range. If you break the blade of your pen- J knife you cannot mead 'it by simply placing) in contact the broken pieces; the-gap,i though perhaps risible - only to the best microscope, is still too great, for ; the co-! hesional forces to bridge. - Gravitation has no such limitation in its range, The sua holds tho earth and each of us whirling, about him in the yearly round, despite his distance of ninety odd millions of miles.! Now, the forces acting between electrons are like gravitation, only they are enor- ;■ mously more powerful than the gravitational forces between atoms; they are not limited> ;; in their range like the cohesional forces of atoms. A curious characteristic of the electron is that it repels an electron similar ■ to itself just as strongly as it attracts <a*s of the opposite sort. Thus a charge of electricity, or, in other words, a collection- / of electrons of the one kind, instead of :; cohering as a solid body does, spreads itself ", out as far as it can, and is continually try-; ing to thrust itself to pieces. But as nearly all pure substanecs refuse fco allow , the electrons to pass, a charge of electricity can be held together in spite of its own efforts '; towards infinite expansion.' However, there : is one remarkably exceptional class of sub- " stances, namely, the metals, which allow, the electrons to pass freely through the interstices between their molecules and atoms, so that if a charge of electricity is given to ■ a piece of metal ii spreads all over its surface. The possession of this property of allowing electrons to move through it make. 1 . the. substance a conductor of electricity—th'J less resistance it offers the higher is its conducting power. . . The only sign that Nature gives of he/ . vast stores of electricity is in the play 01 tho lightning and the splendours of tha auroral streamers athwart the Arctic and • Antarctic nights. Man, by building up , observation and experiment on the little; fact j'. - that rubbed amber attracts fragments of : straw, at last got high enough for a goodview into the great secret that lightning and. ; aurora give a hint- of, and has found that by the. simple mechanical ' contrivance of ihe l dj-namo the two sorts of electricity can' bo forced apart at any time and at any place, ( .. - and that by letting them, run together, ;*V V can recover under very convenient i j the greater part of the power that he '/■ iip in separating them. It must always remembered that Nature ' has very little ready-made electrical power-that we can tap. In modern engineering electricity does not . count as a source of power, but as by fa* the most convenient means of distributing /.J"iK It does not pay to separate out great quantities of the two electricities at a time, . to bo run together at a future period. On v the contrary, the best plan is to keep separ- - ating out by means of the dynamo just A- / : the rate at which you wish to let the sep&- ! -. rated electricities recombine for the purpose in hand. ' e The mechanism of the incandescent ligM* now becomes very simple to understand by :.. the aid of these modern concepts of electric- -; . ity. The electrons of both kinds aie streaming in opposite directions through the thm;o carbon thread, where they are coiapeUled continually to jostle against the molecules ; of carbon ; the atoms of carbon are set intO;, ;. more and more violent motion, till they _ are _ worked up to a white heat, and radiate; energy in the form of bright light exactly, at the " 'same rate as the - electrons. bumping it into them. In the aire light the . atoms vibrating are those ;of . the vaporised carbon..