Jan. 26, 1888] 



NATURE 3^ 



303 



maximum, the sea-bed rises suddenly to a depth of only 857 

 fathoms below the surface. 



The new part of the Mittheilungen of the Hamburg 

 Geographical Society contains several papers of interest. Dr. 

 [ Sievers concludes the long series of papers describing the results 

 of his journeys in Venezuela with some remarks on his original 

 route map of the Venezuelan Cordilleras, which are accompanied 

 by an admirable reproduction of this map. In addition to 

 this, Herr Frohberg arranges and discusses the barometric results 

 obtained by Dr. Sievers. Dr. Zintgraff describes the Lower 

 Congo from Banana to Vivi, and insists on the importance of the 

 Congo for the exploration of the region behind the German 

 Cameroons protectorate. Herr Weisser gives a fairly cooiplete 

 account of German New Guinea and the Bismarck Archipelago ; 

 and Herr Hernsheim does the same for the Marshall Islands. 



As a supplement to the Indian Survey Report for i88s-86> 

 there has just been issued the narrative of the journey of a 

 native explorer, M — H, through Eastern Nepaul into Southern 

 Tibet, as far as the town of Dingri, and westwards and south- 

 wards through Central Nepaul. M — H has succeeded in rectifying 

 in many points existing information on the hydrography of the 

 region traversed, and gives many useful notes on its physical 

 geography and its flora, as well as on the people. 



OUR ELECTRICAL COLUMN. 



The additional facts added to our knowledge of electricity 

 in 1887 are not very numerous, but the impetus given to its 

 practical applications was very encouraging. One of the most im- 

 portant scientific discoveries was that of Prof. J. J. Thomson, 

 which formed the subject of the Bakerian Lecture, viz. that sparks 

 in tubes dissociated iodine, bromine, and chlorine. In iodine 

 the dissociation produced at 214° C. was as much as that effected 

 directly by Victor Meyer at 1570° C. 



Prof. Ewing showed that there was apparently no limit to 

 the magnetization of iron in strong magnetic fieldi when we in- 

 creased the magnetizing force, and Prof. Roberts Austen showed 

 that it was impossible to separate the elements of alloys by means 

 of electric currents. 



Immense improvements have been made in the construction 

 of dynamos, motors, accumulators, and secondary generators, 

 and in consequence electric lighting and working of railways and 

 tramways are upon a commercial and useful stage. Many other 

 causes besides restrictive legislation have retarded electric light- 

 ing in England, but there are now many signs that this useful 

 industry is in more senses than one about to commence a very 

 bright career. 



Several useful constants have been added to our note- 

 books during the past year. Dr. John Hopkinson is pursuing 

 his examination of the specific inductive capacity of oils and 

 other liquids. 



Mr. Preece has determined the coefficient of self-induction 

 of straight iron telegraph aerial wires to 0'005 x 10® centimetres 

 per mile, while that of copper wire is practically nil. He has 

 also measured the current which will just actuate a B2II telephone, 

 and he found it to ba 6 x lO"^^ ampere. 



The application of powerful electric currents to smeltinj, as 

 in the Cowles process for producing aluminium, and to welding, as 

 proposed by Elihu Thompson, is gaining rapid progress, while 

 the use of enormous dynamos for the deposition of pure copper 

 from impure ores is gaining ground with giant strides. Messrs. 

 Bolton, at Widnes, and Messrs. Vivian, as well as Messrs. 

 Lambert at Swansea, are each depositing from fo ty to fifty tons 

 of copper per week by currents of from 5000 to 10,000 amperes. 



The Society of Telegraph-Engineers and Electricians has de- 

 cided to change its title to that of the Institution of Electrical 

 Engineers — a change for the better. Mr. Graves, the new Pre- 

 sident, gave an exceedingly interesting address on the industrial 

 importance of electricity, and he brought out the remarkable fact 

 that there are at least 300,000 persons in the United Kingdom 

 depending upon electrical industry for their daily bread. 



Some of our prominent workers in the field of electricity, 

 such as Lord Rayleigh, Sir William Thomson, and Prof Hughes, 

 are conspicuous by their absence during the past year, although 

 the two former have been by no means idle in other directions. 



A NOTE ON VALENCY, ESPECIALLY AS 

 DEFINED BY HELMHOLTZ,^ 



'\7'ERY little has been either said or written of late on the sub- 

 * ject of valency — not because the topic is admitted to be 

 exhausted, nor because our views can be regarded as reposing 

 on a fixed basis of fact, but more I believe on account of the 

 feeling being almost universally entertained that little is to 

 be gained by continuing the discussion from our present 

 standpoint. 



My purpose in this note is to call attention to the extreme 

 importance of reopening the discussion on account of the 

 intimate bearing that it has on the work in which the 

 Electrolysis Committee, jointly appointed by Sections A and B, 

 are now engaged ; and to urge that it is time that the gage 

 thrown down by Helmholtz in the Faraday Lecture (Chem. 

 Soc. Trans., 1S81, p. 277) was uplifted by chemists. 



We are told by Helmholtz that it is a necessary deduction 

 from the fundamental law of electrolysis established by Fara- 

 day, that definite, as it were atomic, charges of electricity ai-e 

 associated with the atoms of matter ; that, in fact, a monad 

 bears a single charge, a dyad two, a triad three ; and that 

 when combination occurs the charges are still retained by the 

 atoms but neutralize each other — "thj atoJis cling to their 

 charges, and opposite electric charges cling to each other." I 

 cannot help thinking, however, that Helmholtz deprives his 

 statement of much of its force and simplicity by adding : 

 "But I do not suppose that other molecular forces are 

 excluded, working directly from atom to atom." He is led to 

 do this apparently by being aware of the distinction which it 

 is usual to draw between atomic and molecular compouads. 

 The attempt should at all events be made — and in my paper 

 on "Residual Affinity" I have already ventured the first step 

 — to include both classes of compounds, molecular as well as 

 atomic, in the discussion ; indeed it is somewhat difficult to 

 reconcile the passage above quoted with the following state- 

 ment which occurs previously in the lecture: "The law of 

 the conservation of energy requires that the electromotive force 

 of every cell must correspond exactly with the t )tal amount 

 of chemical forces brought into play, not only the mutual 

 affinities of the ions, but also thne mino/ molecular' attradims 

 produced by ike -wa'.er and other constituents of the fluid." 

 The italics are mine. But if the " minor molecular attrac- 

 tions " contribute to the electromotive force of the cell, then 

 conversely these also will have to be overcome in effecting 

 electrolysis, aid are as much to be reckoned as are the "mutual 

 affinities of the ions " ! 



It is obvious that if it should prove possible to decide what 

 nu nber of charges are necessarily associated with any particular 

 atom, the conception of valency will have acquired a definiteness 

 which cannot possibly be attached to it as lon^ as the views that 

 have hitherto guided us are adhered to. A decision must involve 

 the discussion of the question of the existence of molecular as 

 distinct from atomic compounds. 



To cast the apple of discord without further preface, I would 

 direct attention to the insufficiency of the evidence on which it 

 is usual to rely as proof that nitrogen, for example, is a 

 pentad ; nay more, I would assert that this very evidence should 

 be interpreted as proof that nitrogen is not a pentad. It is 

 commonly held that the behaviour of the alkyl tetra-substituted 

 derivatives of ammonium is such as to negative the idea that 

 these are " molecular compounds " of triad nitrogen, and that 

 it must be assumed that the elements of the binary compound 

 which are added to the ammonia derivative are distributed 

 in the ammonium derivative ; for example, that in the formation 

 of tetramethylammonium iodide from tri nethylamine and methyl 

 iodide the methyl and iodine of the iodide part company and 

 separately attach themselves to the nitrogen, thus : — 



CH, 



.CH, 



^N— CHj 

 ^ \CH. 



But I contend that the properties of tetramethylammonium iodide 

 and hydroxide prove that such is not the case : the iodide, it is 

 well known, can be boiled for hours with the strongest caustic 

 potash solution without undergoing change ; there is not a single 



' A Paper read by Prof. Henry E. Armstrong, F.R S.. in Section B oC 

 the British Association at Manchester. Communicated by the Author. 



