So 



KNOWLEDGE & SCIENTIFIC NEWS. 



[May, 1904. 



due to the strong acid appropriating the base and turning 



the weaker acid out. For example — 



Sodium acetate + hydrochloric acid = sodium chloride + 



acetic acid. 

 But the ionic view is quite different. Here we assume 

 that sodium ions + hydrogen ions + chlorine ions + 

 acetic ions give sodium ions + chlorine ions + slightly 

 ionised acetic acid, the change consisting in the union of 

 hydrogen ions with acetic ions, the others remaining 

 unchanged. 



It is well known that many salts which are "normal " 

 in the chemical sense yet give an acid or an alkaline 

 reaction \vhen dissolved in water. Thus sodium borate 

 or sulphite shows an alkaline reaction, whereas aluminium 

 sulphate or ferric chloride react acid. This may be ex- 

 plained by assuming that the salt is partly hydrolysed by 

 water in the first instance, giving acid and base in equi- 

 valent quantities. But if the base is strong and the acid 

 is weak the former will be largely, and the latter slightly, 

 ionised ; so that the solution will contain an excess of 

 hydroxyl over hydrogen ions, and will therefore react 

 alkaline. If the base is weak and the acid strong, there 

 will, for similar reasons, be an excess of hydrogen over 

 hydroxyl ions, and the solution will be "acid." 



Many of the ordinary chemical changes may be repre- 

 sented as consisting in an exchange of electric charges 

 between the ions, or in the assumption of charges by 

 neutral substances whereby they become ionic, and a 

 corresponding loss of charges by the ions whereby they 

 become " ordinary " or neutral substances. When dilute 

 hydrochloric acid acts on zinc, for example, the metal 

 passes into the ionic state, assuming positive charges ; 

 whilst the ionic hydrogen gives up its positive charges, 

 liecoming ordinary hydrogen gas, the chlorine remaining 

 in the ionic state throughout. When stannous chloride 

 is converted in stannic chloride, in solution, by chlorine, 

 the change may be regarded as consisting in the assump- 

 tion of two additional positive charges by the tin ion and 

 the assumption of two equal and opposite negative charges 

 by two atoms of neutral chlorine, which thereby becomes 

 ionic. In this action the tin is said to change its valency 

 from two to four (;.f., from the stannous to stannic form), 

 the valency, in fact, being in this sense measured by the 

 number of unit charges with which the atom is associated 

 when in the ionic condition. 



Modern Cosmogonies. 



VIII.— Protyle: Wha.t is it ? 



The la.te Mr. H. C. FYFE. 



1 1 is with the deepest regret that we have to record 

 the death of one of our contributors, Mr. Herbert 

 Fyfe. Mr. Fyfe was only thirty years of age, and 

 his death, though not entirely unexpected, was 

 none the less sudden. He leaves a gap in scientific 

 journalism that none can fill as well as he. Pos- 

 sessed of extraordinary industry and energy, and 

 gifted with a quite unusual capacity for assimilating 

 the mam details of the matter in hand, he wrote 

 articles on many subjects besides the one which 

 was his chief interest — " Submarine Warfare " — 

 and his work never missed its mark. The loss to 

 scientific journalism is great; but the loss to his 

 wide circle of friends is irreparable. One of the 

 kindest and most generous of men, one of the most 

 helpful of colleagues, he leaves behind him a 

 memory not alone of goodness of heart or sound- 

 ness of mental fibre, but of a moral nature that was 

 a great example of courage and sweetness. 



By Miss Agnes Clerke {Hon. Mem.), F.R.A.S. 



The notion of a primordial form of matter meets us at 

 every stage of cosmogonical speculation. It is the out- 

 come of an instinctive persuasion that, if we could only 

 " lift the painted \e\\ " of phenomena, the real business of 

 the universe would be found to be proceeding in the 

 background, on a settled plan, " without haste or rest ;" 

 that uniformity is fundamental, diversity only inciden- 

 tal ; and that the transformations of the one simplified 

 substance might be represented by a single formula, the 

 discovery of which would place in our hands the master- 

 key to the locked secrets of the universe. Among 

 untutored thinkers, some familiar kind of matter, idealised 

 and generalised, commonly stood for the typical world — ■ 

 stuff". Water was the first favourite. Thales, the "wise 

 man " of Miletus, procured his Cosmos by precipitation 

 from an aqueous solution, and many savage tribes have 

 de\ised analogous expedients. Anaximenes preferred 

 air for the universal solvent ; Heracleitus substituted 

 fire, and set on foot a scheme of what is now often 

 designated " elemental evolution." From the perpetual 

 " flux of things," he conceived that the four substances 

 selected by Empedocles as the bases of Nature were not 

 exempt ; and a fragment of his scheme survived in 

 Francis Bacon's admission of the mutual convertibility 

 of air and water. In the main, howexer, the author of 

 the " Novum Organum " adhered to the Paracelsian 

 doctrine of an elemental triad,- while rejecting the saline 

 principle, and retaining, as the material substratum, 

 sulphur and mercury. f 



These twilight fancies faded in the growing light of 

 chemical science ; yet the mental need that they had 

 temporarily appeased survived, and had somehow to be 

 satisfied. An " Ur-Stoft " was still in demand ; but the 

 nineteenth century characteristically attempted to supply 

 it by weight and measure. Dalton's combining equiva- 

 lents afforded the warrant for Prout's hydrogen hypo- 

 thesis. The problem to be faced was to find a unit-atom 

 by the varied combinations of which all the rest of the 

 chemical atoms might be formed. The condition indis- 

 pensable to be fulfilled was that their weights should be 

 exact multiples of that of the unit, and it came near to 

 fulfilment by the hydrogen-atom or semi-atom. It was, 

 nevertheless, a case in which approximate agreement was 

 of no avail ; the adverse decision of the balance finally 

 became unmistakable ; and Prout discreetly fell back, in 

 1831,1 upon the resource of deriving hydrogen itself 

 •' from some body lower in the scale." His hypothesis, in 

 short, dissolved into a conjecture. It had only emphasised 

 the stipulation that the " Protyle" of the ancients must 

 be sucli as would likewise serve for the unification of all 

 the chemical species. 



Meanwhile, the theoretical search for it had been 

 carried on in widely different fields of inquiry. Laplace's 

 speculations, Herschel's observations, had led to the con- 

 ception of some kind of " fire-mist" as the genuine star- 

 plasm. But its nature and properties remained indefinite, 

 or were assigned at the arbitrary choice of adventurous 



' First introduced by Basilius Valentinus. See Fowler's Novum 

 Orgiiinim, p. 57C. note. 



t Thus recurring, as Mr. I'owler remarks (loc. cit.), to Geber's 

 earlier view. 



I Dut of Nalioiuil Ihoj^Viiplty, V I .\L\'I , p 426. 



