268 



NA TURE 



[July 20, 1893 



as such, but will appear in various forms : some of it may be 

 evolved as heat, some as volume energy, some as kiaetic energy, 

 and it 15 even possible by an appropriate contrivance to obtain 

 a large portion of the chemical as electrical energy. But to 

 state that the energy always passes through the electric stage on 

 its way to other forms in which it manifests itself to us is some- 

 thing altogether different. 



The question that Prof. Armstrong tries to answer by the sup- 

 position that the presence of an electrolyte is required in order 

 to bring about chemical change admits of a very different reply. 

 We conceive it to be this : In most exothermic combinations 

 the heat evolved is sufficient, provided the change were to pro- 

 ceed adiabatically, to resolve the compound into its constituents. 

 Why, then, should they react ? To take a concrete instance : — 

 Why should ammonia and hydrochloric acid combine at 

 ordinary temperatures when the heat evolved by their union is 

 sufficient {provided none escape) to raise the reacting molecules 

 to the temperature at which they refuse to combine? For con- 

 venience sake the question is stated in terms of heat, since that 

 is the usual form in which the loss of chemical energy manifests 

 itself to us ; but it is advisable to keep the statement of the 

 question quite general. It appears to us that the answer is : — 

 because the reaction is not adiabatic. Some substances must 

 be present — the walls of the containing vessel, some compound 

 capable of dissociation, some solid body, such as spongy plati- 

 num, which will absorb a portion, perhaps an exceedingly small 

 portion, of energy, and so give the bodies present a chance of 

 interacting without liberating so much energy by their inter- 

 action as would decompose the prospective compound. These 

 views, it may be contended, are speculative. It is true : but we 

 venture to think that they are legitimate speculations, involving 

 a complete survey of the circumstances, and not one-sided and 

 partial like those of the paper we are criticising. 



Assuming the correctness of Prof. Armstrong's main idea, 

 there are still one or two matters of detail where the assumption 

 scarcely feems in harmony with known facts. He assumes that 

 because hydrogen chloride when dissolved in water forms a 

 composite electrolyte, a gaseous mixture of hydrogen chloride 

 and water will also be an electrolyte. This by no means 

 follows, and indeed experiments which have been made in this 

 direction point to the contrary conclusion. The same holds 

 good of his argument as to the combination of nitric oxide and 

 oxygen — water vapour is not known to form a composite elec- 

 trolyte with gaseous nitric acid. 



VVith regard to the regularity displayed by iodine and hydro- 

 gen compared with the irregularity of the results obtained by 

 Victor »\Ieyer with chlorme ar.d hydrogen, it is altogether im- 

 possible to understand Prof. Armstrong's attitude. In one 

 sentence he assures us that "this is not surprising," and in the 

 next that "there is a significant [of what?] difference in the 

 behaviour of the two mixtures, as hydrogen iodide should be- 

 have as hydrogen chloride." He suggests that some special 

 electrolyte may be active in the case of chlorine and hydrogen ; 

 but he is inclined to account for the difference observed from 

 the fact that only one of the reactions is reversible under the 

 conditions of experiment. We quite fail to understand the 

 influence which the reversibility of the reaction would exert, on 

 its regularity. 



In (ine, still assuming for the sake of argument the notion of 

 "reversed electrolysis," we would ask : — -In a mixture of hy- 

 drogen and oxygen, are the ions there, or are they not there ? 

 If not there, will the presence of a vapour bring them into exist- 

 ence ? If there, what is the need of a so-called impurity ? Is 

 it supposed that the impurity will discharge them? Why, then, 

 does not the presence of one or of two conducting wires of the 

 same metal in an electrolyte cause combination of the ions? 

 University College, London, July 8. W. Ramsay. 



James Walker. 



The Corona Spectrum. 



In the preliminary account l)y M. Deslandres of the main 

 results of the eclipse photographs obtained by the French 

 astronomers at Fundium, as reported in this journal on May 25 

 (vol. xlviii. p. 81), it is stated that many new coronal lines have 

 been photographed, and that a displacement of the lines in the 

 light from opposite points of the corona in the solar equatorial 

 plane proves a rotational movement nearly corresponding with 

 that of the surface of the sun itself. 



In the absence of fuller details it is perhaps a little difficult 



NO. (238. VOL. 48] 



to accept without reserve these interesting statements, particu- 

 larly when one considers the somewhat unfavourable condition* 

 under which the photographs were obtained. In the first place, 

 one would like to ask by what means have these new bright 

 lines been identified as belonging to the corona, seeing that, 

 owing to the hazy condition of the air at the aliove station, the 

 brilliant chromospheric radiations were apparently reflected from 

 a considerable area of the sky in the sun's neighbourhood, 

 forming, as it were, a kind of false corona with a bright line 

 spectrum. So obvious, indeed, is this atmospheric spreading of 

 the chromosphere lines in the spectrum photographs obtained 

 by the English astronomers at the same station, that many line» 

 are shown as clearly on the moon's disk as in the coronal 

 regions; the calcium lines "II" and " K," which are very 

 brilliant chromosphere lines, are in these found to extend con- 

 siderably above the limits of the true corona, as defined by its 

 continuous spectrum, and are also found equally bright acros* 

 the dark moon. 



From the above considerations one is inclined almost to doubt 

 whether, after all, any true corona lines have ever been proveif 

 to exist, excepting perhaps the line 1474 (K), which is not 

 ordinarily a brilliant line in the chromosphere, and would there- 

 fore not be easily seen by atmospheric reflexion ; ' and it would 

 seem possible, if not probable, that this beautiful solar appen- 

 dage, with its dark rifts and curving streamers, shines simply 

 by continuous light. 



Definite information on this point %vould, however, be gladljr 

 welcomed by those who are endeavouring to photograph th* 

 corona without an eclipse. We would, in fact, clutch it any 

 straw, in the shape of a bright line, in the hope of its yielding 

 a true image of the coronal forms, and it was hoped that the 

 recent eclipse would furnish evidence which would settle thi*. 

 question. 



With regard to the second point, namely, the displacement 

 of lines in the coronal spectrum. This is said to be equal to 

 a velocity in the line of sight of 5 to 7 kilometres per second 

 (I presume for the total difference of position of the line), say 

 3 kilometres for the speed of approach or recession at a dis- 

 tance from the solar limb equal to two-thirds of the diameter. 



This is certainly a very striking result, and if confirmed by 

 further study would in itself go far to prove the true corontu 

 nature of the line measured. A displacement is conceivable^^ 

 it is true, under certain conditions, on the assumption that 

 the light is reflected chromospheric light, but this would not 

 exceed a velocity of i'S7 kilometres, whilst the above resute 

 comes not far short of an angular rotation equal to that iK 

 the disk itself. .A. point at the distance named would, if 'igidv 

 connected with the sun, alternately approach and recede at S 

 speed of about 4'35 kilometres per second. \ 



It would be interesting to know, however, what are ihelimiti 

 of error in these measurements. I gather that a high di$per> 

 sion was not employed, and it would seem, therefore, that a 

 large uncertainty may be expected ; supposing, for instance, that 

 in the original negative the lines H and K are depicted 25 mm. 

 apart, the total displacement corresponding to 7 kilometres 

 per second will only amount to 09 mm. ; an error, therefore, of 

 j^u mm., or lo'su of an inch (corresponding to over i^ kilo- 

 metres) would materially affect the result ; and to come within 

 this limit would require unusually fine definition in ths line 

 measured. 



In view of the novelty and great importance of the con- 

 clusions .arrived at by the leader of the French eclipse expedition 

 to Senegal, students of solar physics willt await with keen in- 

 terest, not to say impatience, the publication of a full detailed 

 discussion of the results obtained. J. Everskei). 



Kenley, Surrey, July 2. 



Lord Coleridge and Vivisection, 



My attention has been called to a letter which the Lord 

 Chief Justice has written in support of an endeavour which is 

 being made by a section of the Society for Promoting Christian 

 Knowledge to withdraw from circulation my little work " Our 

 Secret Friends and Foes, " recently published in their " Romance 

 of Science Series." Until the Publication Committee of the 



1 It seems pretty certain, however, from the clearly-detined cor-^nal 

 "rings" seen by Prof. Lockyer and odiers at former eclipses by means of 

 an objective prism, that a more or less unifjrm gaseous extension must 

 exist far above the chrornosphere and prominences ; but is this the corona 

 proper ? 



