Oct. 10, 1878] 



NATURE 



625 



areas, easterly, hare a certain regularity, it is soon learnfed 

 to tell nearly when the effect of any area noticed as ap- 

 proaching will commence to be felt. The instrumental 

 signs of the weather case will show the changes com- 

 mencing, and it may be judged whether or when the 

 weather conditions noticed in the approaching area are 

 likely to prevail. Some elementary knowledge of 

 meteorology is needed ; but much can be done by a 

 careful watching, solely. The instruments of the weather 

 case will show the changes anticipated when they begin 

 to be felt and before they hare arrived in their, full force. 

 ■ : If the area noticed has been large or small^ with 

 weather conditions decided or yariable, it can, from these 

 facts, be judged often if the " coming weather," of what- 

 ever kind it may be,. will be steady for a day or for days, 

 or more rapidly changing. The case makes practicable 

 otker *indiB9any^tudies. ; . . ;, 

 ."..-.-::;..:...-. . Albert J. Myer, 



. ;' :^: . .; , Brig.-Gen. (Brevet Assg'd.), Chief 



-. iiit~: Signal Officer, U.S.A. . ■ 



- -"War Department, - - 



Office of the Chief Signal Officer, - '-■■ — :. - - 



j^ . lVashingio>i,D.C.,-July'Zi,'i^jS '■■■-—'■■ -^ 



Vf^-e- TME^'ELEMENTS''^ ELEMENTARY f' 



TT would be a curious speculation were one to ask one's 

 •*- self what is the atomic weight of ozone.? Is it 24? Is 

 US atomic formula Oi '5 ? or has oxygen the atomic weight 

 t)f 32 and ozone of 48, and are the molecular weights 

 64 and 96 respectively ? This can scarcely be, for the 

 srhallest amount of oxygen in two volumes of a gaseous 

 compound of that element is certainly not 32, but 16 parts 

 by weight. In fact atoms of allotropes scarcely appear 

 to exist, the molecule appears to be the smallest amount 

 of one of these substances that can exist either in, or out 

 of combination. But can elements really exist in com- 

 bination under various allotropic forms? We do not 

 know. Weber thinks they can, Clarke thinks they can- 

 not. The example of graphitic acid sometimes cited as 

 proof of the existence in the combined form of allotropic 

 carbon does not appear to me to prove either one view or 

 the other. Graphite, may we not say, is an intermediate 

 stage in the formation of graphitic acid from carbon ? 

 -But it does not follow that the carbon in that acid is in a 

 form different from that under which it exists, say in 

 sugar. But it is exceedingly difficult, as yet, to attach a 

 definite meaning to such a statement as " Carbon exists 

 ntider differait forms in this and in that compound," 



The specific heats of allotropes vary. Weber has most 

 carefully determined the specific heats of the modifi- 

 cations of carbon and boron. The numbers t)btained 

 at low temperatures are different, but when we come to 

 those temperatures at which optical differences disappear, 

 'we find that differences in specific heats disappear also. 

 At high temperatures there is but one specific heat for 

 carbon and but one for boron ; at low temperatures there 

 are two or more specific heats for each. This seems to 

 mean that at sufficiently high temperatures there is but 

 one form of carbon and but one form of boron. As Ave 

 do not know the atomic or molecular weights of the allo- 

 tropic modifications of these elements, we can, it seems 

 to me, draw no conclusions of any value concerning the 

 atomic heats of these allotropes, and therefore the fact 

 that the atomic heat of the elements is a constant number 

 may be explained equally well on the hypothesis that the 

 elements are all allotropes of one of themselves, or of an 

 unknown substance, and on the hypothesis that the ele- 

 ments are essentially distinct forms of matter. It is well 

 to bear in mind that, so far as our knowledge of allotropy 

 goes— and it goes but a very little way— we have reason 



« A paper read before the Owens College Chemical Society. Contbued 

 from p. 593. 



to believe that each allotrope has a different molecular, 

 and therefore, probably, a different atomic weight, from 

 every other allotrope of the same element ; and, further^ 

 that we know that allotropes are at high temperatures 

 resolved into one and the same form. Phosphorus has an 

 abnormal vapour density : two volumes of the vapour of 

 this body contain four (relative to hydrogen as two) 

 atoms; red phosphorus (P^) changes into common phos- 

 phorus (P,) at comparatively low temperatures, therefore 

 we do not know the vapour density of P^. At a point 

 not far from its boiling point, two volumes of the vapour 

 of sulphur contain six atoms (if S = 32)5 at a higher 

 temperature two volumes contain two atoms. We appear 

 to have here a real gaseous allotrope. Is it analogous 

 with, ozone ? Is it not therefore probable that the den- 

 sities of P, andP^ would be found to be different, sup- 

 posmg they were both obtained as vapours ? But even 

 P„ is abnormal. May it not be, then, that we have not 

 as yet obtained normal phosphorus at all ? That what 

 we call phosphorus is an allotrope of the true phosphorus, 

 viz., Pj? May it not be that at very high temperatures 

 P. splits up and yields true normal phosph(»ous vapour? 

 jNow let. us briefly glance at isomers, or -compounds 

 having the same composition, but with- different molecular 

 weights. The mere .fact that compounds of the same 

 composition, but different molecular weights, exist, espe- 

 cially when taken in conjunction with the furthw fact 

 that different compounds having the same cornposition 

 and the j«/«^ molecular weights also exist, renders the 

 theory that. the elements are really compound bodies not 

 altogether improbable. So httle has been done, in the 

 way of exact determinations of the specific heats, specifi<i 

 volumes, and other physical constants, of isomeric bodieS> 

 that I forbear from pressing the facts that are known iiito 

 the argument, but content myself with saying that a more 

 or less simple relation appears to exist between the phyf 

 sical and the chemical nature of the various isomers. 

 The generally accepted theory of isomerism seeks to 

 account for the facts by supposing that the atoms of 

 isomers having equal molecular weights are differently 

 arranged : another theory — to me it appears that the 

 one theory is complementary of the other — supposes that 

 the differences in the action of isomers are to be traced to 

 differences in the amounts of "energy" possessed by 

 these isomers (would it not be better to say, to differences 

 in the relations between the potential and kinetic energy 

 of isomers, and also perhaps to differences in total 

 energy ?) ; whichever theory is applied to isomers may be 

 equally applied to the elements, on the assumption that 

 these bodies are really compounds of one simple form of 

 matter. 



The positive evidence in favour of the theory of the 

 non-elementary nature of the so-called elements is not 

 very great. Yet, to say that the elements are truly ele- 

 mentary is, I am persuaded, a statement which is not 

 justified by the facts which we possess. Either hypo- 

 thesis may be adopted as a working hypothesis : the 

 former, that the elements are not elementary, is, it seems 

 to me, likely to lead to more discoveries, and to pave the 

 way to more far-reaching generalisations than the latter. 



But why should no one have succeeded in decomposing 

 one of the so-called elements ? In a sense we have suc- 

 ceeded. Ozone is an element, but it can be decomposed. 

 Oxygen may, I think, be said to be a simpler form of 

 matter than ozone. The introduction of the battery into 

 chemistry led to the decomposition of potash and soda ; 

 the introduction of new engines of research may lead to 

 the decomposition of some of those bodies, our conclusions 

 regarding the elementary nature of which rests upon the 

 same kind of evidence as did the conclusions regarding the 

 elementary nature of potash and soda before the experi- 

 ments of Sir Humphrey Davy. Analogy prompts us to 

 ask. Is it not possible that what we cannot accomplish in 

 our earthly laboratories may be actually brought about 



