M.A 



1904.J 



KNOWLEDGE & SCIENTIFIC NEWS. 



cosmogonists. So the " shining fluid " of space was 

 "everything by turns and nothing long," until Sir 

 Wilham Muggins, in 1S64, o'l^'^^' 't spectroscopic indi- 

 viduality. The " recognition -mark" of nebulium is a 

 vivid green ray, by the emission of wliich it is known to 

 iiave a concrete existence, ^'et th,' little that has besides 

 been learned about it discountenances its identification 

 with the mattria informis of anti(iue philosopliy. This we 

 should e.xpect to be the subtlest of all substances. Pro- 

 fessor Campbell, however, has gathered indications tliat 

 nebulium is denser than hydrogen. Its luiiiinosity, at 

 least, which is invariably associated with that of hydro- 

 gen, extends further in the same formations; it seeks a 

 lower level. The nebulium-atom is not, then, the 

 chemical or the cosmical unit. 



This evasive entity, or something that curiously simu- 

 lates it, has proved to be of less recondite origin. Sir 

 William Crookes is amply justified in claiming the 

 venerable designation of Protyle for the " radiant mat- 

 ter " first produced in his vacuum-tubes nearly thirty 

 years ago. The discovery was astonishing and unsought ; 

 and its significance has not yet been measured. Matter 

 assumes the " fourth state," in which it is neither solid, 

 liquid, nor gaseous," under the compulsion of an electric 

 discharge in high vacua. At an exhaustion of about 

 one-millionth of an atmosphere, the manner of its transit 

 abruptly alters. Conduction gives way to convection. 

 Luminous eflects are abolished. The tubes cease to 

 glow with brilliant, parti-coloured stria; the poles are 

 no longer marked by shimmering halos or brushes ; 

 only a green phosphorescence is seen where the glass 

 walls of the receptacle are struck by the stream of pro- 

 jected particles. They come, with half the velocity of 

 light, exclusively from the negative pole, the positive 

 pole remaining inert. Hence the name " cathode-rays." 

 bestowed by Goldstein on the carriers of electricity in 

 highly-exhausted bulbs. 



These mysterious, sub-sensible agents possess certain 

 very definite properties. Their paths are deflected in a 

 magnetic field ; they can traverse metallic films ; and 

 their investigation in the open, thereby rendered feasible, 

 has shown them to possess photographic efficacy, and 

 the faculty of l)reaking down electrical insulation ; more- 

 over, they transport a negative charge of fixed amount, 

 and have a determinate momentum. They are then 

 assuredly no mere pulsations of the ether ; unless our 

 senses " both fail and deceive us," their quality is ma- 

 terial. Material, yet not quite with the ordinary 

 connotation of the term. The most essential circum- 

 stance about the cathode-rays is that they remain un- 

 modified by the chemical diversities of the originating 

 gases. t X hydrogen tube yields identically the same 

 radiant matter as an oxygen or a nitrogen tube. Here 

 then at last ^ve hav'e within our grasp undifferentiated 

 substance — matter not yet specialised, neither molecular 

 nor atomic, matter destitute of affinities, exempt from 

 the laws of combination — matter in its inchoate, and 

 perhaps ultimate, form ; in a word, the far-sought 

 Protyle. 



Already, in 1879, Sir William Crookes conjectured the 

 infinitesimal missiles propelled from the cathode to be the 

 " foundation-stones of which atoms are composed." i 

 .■\nd in 1S86 hejpronounced them more decisively to be 

 the raw material of atoms, which, to Sir John Herschel's 

 apprehension, bore the unmistakable stamp of a " manu- 



• Crookes, I'bil. Trans. Vol. CLXX , p. 1O3 



t J. J. Thomson, The Discharge uf Ehclricilv through Gases, p. 195 ; 

 Phil. Mag. Vol. XLIV. . p. jii , 



j Science, June 26, 1903. 



factured article." Nor did his recent commentator re- 

 frain from attempting distantly to divine the method of 

 their construction, or from laying his linger on the by- 

 products and residues associated with it,' , although \\{\ 

 felt compelled to relegate the cosmic factory to the edge 

 of the world, where inconcei\'al)le things may happen. 

 All this, indeed, seemed, in the late Victorian era, like 

 mounting the horse of Astolfo for a trip to the moon ; and 

 sane common-sense pronounced it fantastic enougli to 

 " make Democritus weep and Heracleilus laugh." I Hut 

 we have since learned from Nature hersell some tolerance 

 of audacities. 



Step by step, the new order uf ideas has irresistibly 

 come to ihe front. It owed Us origin to Sir William 

 C'lookes's skill in producing high vacua, and the con- 

 secjuent development in his tubes of radiant effects. 

 Then, in 1879, uni\ersal importance was claimed for 

 them, and matter in the ''fourth state," by a revival of 

 the dreams of the ancients, expanded into a kind of 

 visionary Protyle. Philipp Lsnard made the next ad- 

 \ance towards its actualisation by slipping it, in 1894, 

 through an aluminium window, and watching its 

 behaviour towards ordinary matter. Two years later, 

 l^bntgen-rays made their entry on the scene ; and before 

 the end of 1896, Becquerel, hurrying along the track of 

 novelties, came upon the momentous discovery of radio- 

 activity. 



A revision of ideas has ensued. Some time-honoured 

 assumptions have had to be discarded ; so-called laws 

 have been found to need ijualification ; the (jid system of 

 physics is consequently out of gear, and much time and 

 patient labour must be expended upon the adjustment of 

 the new and improved system destined to replace it. The 

 leading and indisputable fact of the actual situation is 

 that a number of hitherto unsuspected modes of energy 

 lia\e been disclosed as widely operative in Nature. All 

 are of a " radiant " character. They travel in straight 

 lines with enormous speed ; they start from a material 

 base, and pr(.)duce their several effects on reaching a 

 material goal. Now these effects are closely analogous, 

 notwithstanding that the rays themselves are radically 

 dissimilar. Those of the cathodic kind are corpuscular. 

 They consist of streaming particles, each, according t(j 

 Professor J. J. Thomson, of about one-thousandth the 

 mass of the hydrogen-atom. Others — the noted "alpha 

 rays " — are atomic ; they are supposed to aggregate into 

 helium. Finally, the Ii<)ntgen variety are ethereal ; they 

 are composed of light-vibrations reduced in scale, and 

 augmented correspondingly in frequency. What is most 

 remarkable is that these various forms oi activity gise 

 rise, by different means, to very much the same results. 

 They are, in fact, distinguishable only by careful observa- 

 tion. They possess in common, though not to the same 

 degree, the faculties of penetrating opaijue matter, of 

 impressing sensitive plates, of evoking fluorescence ; 

 while under the impact of cathode and Rontgen rays, as 

 well as of ultra-violet light, insulated electric charges 

 leak away and evanesce. There is, however, one clear 

 note of separation between cathodic and X-rays in the 

 sensibility of the former, and the indifference of the latter, 

 to magnetic intiuence. Thus alone, it would appear, is 

 electrified matter set apart from what we call ether. If 

 tlying corpuscles could be obtained in a neutral condition, 

 the distinction would vanish. But this is evidently im- 

 practicable. Indeed, advanced physicists abolish the 

 material substratum of the corpuscle, and assign its attri- 

 butes to the associated atom of electricity. It is, at any 



* i'roc. Chem. Sociely, March 28, iSSJi. 

 t Times, Marcli 30, 1888, 



