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forest (broken up as it is into bars of light and shade), by the tion of the valleys, and therefore can branch out from the plateaux eyes of their fierce and hungry foes as well.

in any direction. If this is so, there is an end of Mr. Crotch's A careful examination of the varied stripes of the zebra has theory, and the only difficulty left to explain would be why, forced upon my mind the conviction that they have a still deeper when the lemmings reach the sea, they still continue on their meaning and value than has hitherto been noticed and onward course to perish in their multitudes by drowning. The explained.

answer to this, however, is not far to seek. For their ordinary It is easy to see how the vertical bars may assimilate to the habits are such that when in their wanderings they come upon falling shadows in the noonday sun, and the diagonal stripes on a stream or lake, they swim across it ; and iherefore when they the neck and hind-quarters to those cast by the declining day. come upon the coast line it is not surprising that they should But it is not so much in the day-time and during its waking hours behave in a similar manner, and, mistaking the sea for a large that the zebra stands in such pressing need of concealment as lake, swim persistently away from land with the view to reachat night, when it is compelled to rest. Then, when surrounded ing the opposite shore, till they succumb to fatigue and the by eager and wakeful foes, it dues require all the concealment it waves. Therefore, pending further observations on the question can get. Now, let us suppose the animal to be lying down, of fact above alluded to, I cannot feel that the migration of the say partly on its side and partly on its belly, as horses very lemming furnishes any difficulty to the theory of evolution over frequently do. What will be the effect of such an attitude upon and above that which is furnished by the larger and more imthe different stripes on various parts of the body? In the first portant case of migration in general, to the consideration of place, the animal will thrust out its knees, and fold its fetlocks which I shall now proceed ” (“Mental Evolution in Animals,” backwards under its body in such a manner that the horizontal pp. 284-85). bars on the fore-legs will become vertical.

Mr. Duppa-Crotch's theory thus alluded to—which constiAt the same time it will push out in a backward direction, its tuted the most striking feature of his " rather lengthy paper haunches, and the hind-feet will be brought forward under or before the Linnean Society,” and which, he then wrote, Dear its body, so that the diagonal stripes on the hind quarters me to spend two years in the Canaries and adjacent islands" will be drawn so as to become much more vertical, and to is, briefly, as follows: correspond with the now vertical bars across the hind-legs, made “I allude to the island or continent of Atlantis... It is vertical by the folded position of the limbs. In such an atti. | evident that land did exist in the North Atlantic Ocean at no tude-a perfectly natural and common one--all the stripes of very distant date. Is it not then conceivable, and even the body will be vertical, or nearly so, especially if the zebra probable, that, when a great part of Europe was submerged, rests its head upon the ground, or its fore-legs, so as to bring the and dry land connected Norway and Greenland, the lemmings diagonal stripes of its neck into unison with all the rest. Sup- acquired the habit of migrating westwards, for the same reasons posing, then, that a coincidence in the general direction of the which govern more familiar migrations? : . It appears to stripes is produced by such an attitude of the body during rest, me quite as likely that the impetus of migration towards this is it too much to assume it to be an extension and refinement of continent should be retained, as that a dog should turn round those protective devices of Nature, extending to the sleeping before lying down on a rug, merely because his ancestors found zebra ihe full amount of all the possible protective value of its it necessary thus to hollow out a couch in the long grass” (Linn. stripes just at the very time when it needs it most, so that in the Soc. Journ., vol. xiii. p. 30). clear tropical moonlight, when the shadows are only a little less And, in a subsequent paper (ibid., p. 157 et seq.), he distinct than in the day, it may be able to repose in something combats the statement of Mr. Collett, "that these migrations like safety and peace ?

follow the natural declivities of the country. Now, however, But, suppose the zebra rests, not always on its belly, as sug. it appears that Mr. Collett turns out to be right as to the gested, but now and then on its side, with its limbs outstretched. fundamental fact of the migrations not being westerly more It is plain that the vertical, diagonal, and horizontal stripes than towards any other point of the compass ; for Mr. Duppa. would then be all more horizontal than anything else, but | Crotch, in his letter to you, acknowledges that, in regard to this pointing in different directions, and would then so assimilate point, which he previously maintained against Mr. "Collett, he themselves with the crossed and varying directions of the shadows "was betrayed into an error by trusting to common report and as to have the same practical effect in hiding the sleeping animal insufficient personal experience.” Nevertheless, he still mainfrom its foes.

tains that the lemmings in their migrations "do not follow the Under such a supposition (by no means an impossible one), water-shed.” it seems to me that those beautiful bars of brown and white The questions, therefore, which I have to put are: (1) What surround the dormant zebra with a protection and a defence are the grounds on which Mr. Duppa-Crotch continues to differ almost as secure as bars of iron or brass, leaving the foes with from Mr. Collett touching this minor point? ; and (2) Does he nothing but their sense of smell to guide them to their prey. still maintain his theory with regard to the island or continent

We have only to assume the folding up of the limbs, like the cf Atlantis," since he has found himself in error upon the major folding up of a two-foot rule, until the marks on both sides cor- point ?

GEORGE J. ROMANES. respond, and we see at once the unification in the general direc- Christ Church, Oxford, January 6. tion of all the stripes of the body, which I cannot help believing has a very considerable protective value to the zebra. However, if any enlightened and generous patron of science

Destruction of Immature Sea Fish. would kindly present to our College (“Owens," Manchester) a It might be supposed that the “ importance of the subject " good stuffed specimen of a recumbent zebra in the attitude i would have induced Mr. Walker, at all events, to examine Dr. have suggested, he would help considerably to settle a nice point Fulton's observations at first hand, before criticizing them in the matter of protective colouring, and give to the cause of (NATURE, December 24, 1891, p. 176), instead of confining scientific education a very welcome and appreciable aid.

himself to reading a review. December 21, 1891.

H. W.

It may be pointed out that Dr. Fulton's computation of the

number of young fish captured is intended to apply only to the The Migration of the Lemming.

Solway, as indeed may be gathered from your review, and being,

not a matter of hearsay, as implied by Mr. Walker, but founded THERE are two questions which I should like to ask Mr. W. on an average of fifteen hauls extending over nine months of the Duppa-Crotch touching his recent letter on the above subject year, is likely to be pretty near the mark. (NATURE, December 31, p. 199); and for this purpose I had In examining Mr. Walker's own computation, we find that better begin by quoting a paragraph from my own discussion of he reckons six days' fishing tu the week, instead of four, which the same subject, written close upon ten years ago :-.

is Dr. Fulton's estimate, based on local inquiry; and we may “Looking to Mr. Collett's large experience on the subject, say that, if Mr. Walker has succeeded in utilizing every working as well as to the intrinsically probable nature of his views, 1 day during any one year of his trawling career, he must have think we may most safely lend countenance to the latter. The been singularly fortunate in his weather, or must have confined most important point of difference between Mr. Crotch and Mr. himself to very sheltered waters. I think it will be conceded Collett has reference to a question of fact. For while Mr. that a calculation derived from actually counting the catch is Crotch states that the migrations are made westwards without more trustworthy than one derived from an observation (or was it reference to the declivities of the country, Mr. Collett is only an estimate?) of weight. If, however, “ 10 cwt. of young emphatic in saying that 'the wanderings take place in the direc- flukes, ... not one the size of half-a-crown," is really only the


sixtieth part of a day's destruction in the Formby Channel, it is one can see immediately that for the latitude of London at that a wonder that there are any lest.

remote period, the Cross would be seen at the southern horizon, A point emphasized in the review, but seemingly missed by and that Sirius then did not rise at all.

K. HAAS. Mr. Walker, is that the young fish are always promptly returned Vienna. to the sea by the Solway shrimpers, and the fact that the industry flourishes in spite of the delay so caused shows that the destruction which ensues from the practices described by Mr.

Simple Proof of Euclid II, 9 and 10. Walker is quite unnecessary. Dr. Fulton has experimentally IN NATURE of December 24 (p. 189) a simple proof of proved that the proportion of young flat-fish of a certain size Euclid II. 9 and 10 is given, which it is stated is believed to be (say above an inch) that would not survive if returned to the It may therefore be of interest to your readers to know sea is small, so that it is evident that Mr. Ascroft's “axiom that these proofs. are given in an edition of Euclid which we that 90 per cent, of fish that come on board a boat is destroyed have now in the press. As the author, Mr. Brent, is resident holds good from no fault of the trawl itself, but simply from a at Dunedin, New Zealand, we are unable to state whether he discreditable carelessness or the part of the man.

lays claim or not to any originality in respect to them : in any Mr. Walker's experiences at the mouth of the Dee show that case, as he has been engaged in mathematical teaching for many the shrimps and the young soles (species ?) have different habitats

years, these and similar proofs of other propositions in Euclid in that river, so that his suggestions as to the limitation of II. have clearly been more widely employed than has been shrimp-trawling seem rather superfluous, since it may be supposed.

PERCIVAL AND CO. supposed that the trawler would fish where he knew he could 34 King Street, Covent Garden, London, January 4. get shrimps, and not go out of his way to catch what he did not want. I have noticed myself on the west coast of Ireland that the minute post-larval Aat-fish, smaller than those dealt with by Fulton, and which are undoubtedly killed by the THE ALLEGED DISCOVERY OF A BACILLUS meshes of the sbrimp-trawl, were never taken on ground

IN INFLUENZA. frequented by shrimps, where, indeed, as one may judge from the relations of the two forms in captivity, the weaker would FRO

ROM the behaviour of influenza as an epidemic, it have a poor chance of surviving.

seems not unreasonable to suppose that it may Everyone will agree with Mr. Walker that it is most necessary have as its cause a living and multiplying organism ; to ascertain the habitat of the young fish at different times of and when influenza reappeared, after an interval of many the year, and to this end the energies of the Marine Biological years, in the latter part of 1889, and more especially Assoc ation in England, the Fishery Board in Scotland, and

since its communicability from person to person, forthe Royal Dublin Society in Ireland, have been for some time directed ; and the assistance that might be rendered by a series

merly disputed, has come to be generally admitted, the of observations by one possessing the experience and oppor

public mind, medical and lay, has been in expectation tunities of Mr. Walker would be incalculable. Until, how

of the announcement that a specific microbe had been ever, our knowledge on the subject is much more complete, I discovered as the cause of the disease. question the advantage of strewing boulders about the bottom Even in diseases, however, of which the characters of the sea. Even if they remained to accomplish their purpose point most strongly to a parasitic microbe as their cause, of interfering with trawling, there is the danger that they would the discovery of such an organism is by no means an form an attractive shelter, not to the young fat-fish that stand easy matter. Thus, no micro-organism has as yet been in no need of it, but to some of their natural enemies.

identified as the cause of small-pox, although this wisease Dublin, December 27, 1891. ERNEST W. L. HOLT.

is always more or less with us; breeds true ; has distinct characters, and a definite localization on the skin ; and

propagates by a contagion which retains its activity for A New Precessional Globe.

very long periods-circumstances which point to a specific To facilitate the understanding of the effects of precession, I organism as its cause, and might be thought to facilitate have made a new arrangement of the celestial globe.

its mounted in the new way can give a representation of the starry heavens for every place on the earth, and for any date, both past

properties of the hypothetical influenza microbe to be and future.

as follows. The diffusibility of the poison through the The globe is fastened in a ring, so that it can be turned round air shows that it must be very minute and readily susan axis ihat goes through the poles of the ecliptic, but can also pended. For the same reason it must belong to the be fixed in any position by a pair of screws. The amount of class of aërobic organisms, i e, those for whose existence turning is to be measured by a divided circle.

oxygen is necessary, or at any rate not hurtful. It must The ring above mentioned--which we will call ring 1.-is multiply with extreme rapidity. It must be capable of movable in another ring (ring II.), round an axis, which forms multiplying in the bodies, or secretions, of human beings; a right angle with the axis formerly mentioned. The inclination between ring 1. and ring II. can be measured by an index ;

and probably also in some medium or media outside the it must equal the obliquity of the ecliptic.

human body-perhaps on damp ground-surfaces, or in Ring 11. is fastened finally in a third and extreme ring (ring confined air laden with dust and organic matter. One III.), so that it can be turned round an axis which forms an angle can hardly suppose it capable of multiplying in pure air, of 90° with the axis of ring II. Ring III. is mounted on a stand as it would lack pabulum ; perhaps, as Dr. Symes with a horizon-circle, so that its axis can be inclined at pleasure Thompson suggests, particles of organic dust floating to the plane of the horizon-circle. The inclination may be read in the air may serve as rafts for it to live on. As, howon a scale engraved on ring III.

ever, influenza prevails under the most opposite conditions To adjust the apparatus to show the firmament at any of season, climate, and weather, oựr supposed microbe, if appointed place and time, one must place ring III. so that its it can live in the air, must be able to fourish under a inclination towards the horizon-circle equals the latitude of the great range of temperatures and degrees of humidity. I place. Then ring II, must be turned so that its plane coincides with the plane of ring III. The angle between I, and II. must

am not aware of any instances of long retention of conbe equal io the obliquity of the ecliptic at the appointed time. tagion, such as would lead us to postulate the possession Finally, the globe must be turned round the axis which goes siderations we might have expected that it would be more

From these conthrough the poles of the ecliptic, till the point of the heaven, which is the celestial pole for the time appointed, comes under likely to turn out to be a micrococcus than a bacillus. the ax.3 round which ring 11. turns in ring III. If the globe is

From what is known of the pathology of some other then fastened in ring I., and ring I. in ring II., with screws, by diseases of microbic origin, as tetanus and diphtheria, turning the globe in ring III. one can see at a glance which stars it seems possible that the immediate cause of the are setting and rising, and which are always above the horizon. symptoms of influenza may be the presence in the blood By making Vega, for example, the celestial pole (14,000 A,D.), and tissues, not of the microbe itself, but of the poison

A globe is from a priori considerations we must suppose the

manufactured by it. The microbe itself may disappear September last in the Royal Institute for Infectious early in the case ; but the poison formed by it pervades Diseases, and that the result of the exhaustive examinathe whole body, and especially the nervous system, and tion of the cases was the discovery in the matter disproduces profound and lasting effects. An early disap- charged from the patients' lungs of a bacillus found in pearance of the microbe in influenza would explain the no other cases of disease of the respiratory organs, and failure to find it on post-mortem examination ; death from which, as the patient recovered, gradually disappeared. influenza being usually the result of complications rather It is stated that the bacilli were cultivated to the fifth than of the primary disease. Influenza is infectious at generation, and that, inoculated into monkeys and rabbits, an early stage of the disease ; but it is not known how they produced in every case the symptoms of influenza. long the infectious condition may last : some cases point It is added. that these results were confirmed by Dr. to its being infectious as late as the eighth day, and we Koch, who further discovered the same bacillus in the must suppose that, as long as the disease is communicable, blood of patients in the febrile stage of influenza. the microbe retains its vitality.

An account of the discovery is promised in the Evidently there is a power of resistance in the human Deutsche medicinische Wochenschrift, and will be awaited body to the invasion of the microbe, varying in different with interest.

H. F. P. persons, for not all who are exposed to the infection contract the disease ; the resistance to it being weakened by depressing influences—as fatigue, and exposure to changes ON THE MATTER THROW.V UP DURING THE of temperature.

SUBMARINE ERUPTION NORTH-WEST OF The resistance to the poison seems also to be over- PANTELLERIA, OCTOBER 1891. centration seems to be necessary in order for the disease WE digs after the end the eruption, but a certain to take on an epidemic form. The pabulum for the microbe, or the number of sus

number of specimens had been secured at the time by ceptible persons, seems also to be soon exhausted ; for the people who went out in boats. Dr. Errera, who helped decline of an epidemic as regards the number of new

us in other ways, kindly gave me some pieces of a bomb cases is often almost as rapid as its increase. At the

from his own collection ; and others, among them a goodsame time the immunity conferred by an attack of in- sized bomb, some 30 inches in its longest diameter, were fluenza is of short duration, for a person may suffer obtained from the inhabitants. Out of a number of repeatedly from the disease; and the same holds as

small pieces from different people, I did not see any regards communities, for many localities have suffered this last, and I have no evidence that any other kind of

that might not have formed some part of a mass such as repeated epidemics of influenza during the last few years; material was erupted. whereas an epidemic of one of the ordinary infectious material was erupted. diseases is usually succeeded by a long period of com

General, Structural, and Mineralogical Characters. parative freedom. These are some of the points which have to be taken account of in any theory of the causation

Riccò (Comptes rendus, November 25, 1891) says that of influenza.

some of the bombs had a diameter of 2 metres, and that During the past week the announcement has been made the prevailing shape was an “ellipsoid of revolution.” in the public press of the discovery by Dr. Pfeiffer, in They were not only porous in texture, but contained large the Royal Institute for Infectious Diseases at Berlin, of a

cavities, and floated for a time, but pieces taken separbacillus which he looks upon as the cause of influenza.

ately are fairly heavy. Riccò mentions a specific gravity It will be remembered that a similar announcement, piece of the coarser material from the inside displaced

of 1'4 (perhaps for a bomb when unbroken). A 4-ounce confirmed. Since then various observers have discovered less than half its weight of water, giving me specific in the sputa and lungs of influenza patients, micro- gravity 2-3. organisms of one kind or another ; but their statements

What most struck the possessors of specimens was are conflicting, and the forms met with are some of them their coaly blackness. Nevertheless, there was on the at least known to occur in other diseases ; so that the in- outside of the bombs a distinctly brownish layer, an ference is that they were either accidentally present, or inch perhaps in thickness, which the eye, or better, connected with secondary affections for which the attack the pocket lens, shows to be due to vesiculation of the of influenza had prepared the way. Whether Dr. Pfeiffer's transparent brown glass that here forms the ground mass remains to be seen ; but the position of its author, and the scribed among others by Dana, from Hawaii (Amer discovery will be more successful in gaining acceptance in certain places vesiculation has been carried so far tha

we have a coarsel type of the "thread lace scoria," de alleged confirmation of his results by Dr. Koch, will no Journ. Sci., March 1888, p. 213, or his book, “Character doubt secure for it a respectful consideration.

As Dr. Koch has pointed out, in order that the relation istics of Volcanoes,” p. 163, 1890). of a particular micro-organism to a particular disease, as

In the brown glass of this part sections show numerous cause and effect, may be considered satisfactorily

proved, and magnetite, and probably a little augite.

narrow crystals of triclinic felspar, and in places olivine the following conditions must be complied with :(1) The micro-organism in question must be present half an inch thick, coarser and darker than the former ;

Beneath this brownish layer may occur another, say in the secretions, blood, or diseased tissues of the subject but which in sections can still be seen to be for the most of the disease.

(2) The micro-organisms in question must be isolated | part brown transparent glass, with the above-mentioned and cultivated-all other organisms being excluded-in minerals in it. suitable media outside the animal body, through several thick, coarsely spongy, black, of pitchstone lustre, which

We are thus led to a layer perhaps an inch or two generations of cultures.

(3) The micro-organisms, thus cultivated, when intro- ' I find a prettier example of this structure on one side of a piece of scori duced into the body of a healthy animal of a susceptible picked up last month near the base of the active cone of Vesuvius. It wa

partly covered by the brown dust ejected since the tapping of the lava od kind must be capable of producing in it the disease in question.

when it was erupted. I find on this, as on scoria that I saw erupted (4) In the animal in which the disease has thus been

October 1889, a tendency to form Pele's hair (on a very small scale).

Unfortunately, the only whole bomb that I saw went to pieces on the produced the same micro-organism must again be found. way to England. The point worth noticing is the difference in structure o

It is stated that, for the investigation of the etiology of different parts ; and I give these rough measurements, taken froin piece influenza, a clinique for influenza patients was opened in

in my possession, merely to show the kind of dimensions with which we


the side of the Atrio del Cavallo last summer.

I do not know, therefore

bounds the internal cavities of the bomb. Sections show that this inner material is largely crystalline. Perhaps one-third of its substance is composed of well-marked crystals of triclinic felspar, olivine, and augite, the rest being a black ground material, opaque in sections of ordinary thickness, except where relieved by microcrystals of felspar.











Foerstner's Description of Specimens from Graham's Isle SiO, 49.87 49-35 49.95 49'24 46.40

46.94 (Ferdinandea).

A1,02 14.80 15071

19'o6 21.84


Iron With the above it is interesting to compare Foerstner's oxides)

15'13 14:40 11-30

II'57 12'23 account of the specimens from Graham's Isle which he Mno

0:49 examined (Min. and Petr. Mitth., V., new series, 1883, ' Cao

10033 9'69 pp. 388-96). I suppose specimens are scarce. He ob- Mgo 6.77

571 4'05 5.00 5:37 tained three. That from Strasbourg consisted of light

1:19 1.69

5957 It gray lapilli, apparently altered by acid vapours. Na,o 2.81 2.96 371 3.89 3:27 1.62

Water differed much macroscopically from the other two.


0:49 0*70 0:63 These lapilli contained magnetite and plagioclase. The other two were as follows (I give an abstract of

9973 100-75

100'47 IOI '18 Foerstner's description) :

(1) Specimen in Museum at Naples was pumiceous and almost foamy, and had a brown ground mass with We may note that Foerstner describes a decrease in glassy lustre, in which crystals of plagioclase, olivine, the amount of silica in the rocks erupted on Pantelleria and magnetite.

itself during the later part of its history. Thus, the (2) Specimen from Palermo (collected by G. Gemmel- oldest rocks of the island are described by him as phonolaro) was black and vesicular, but in sections was very lites, liparites, and andesites, probably of Tertiary age, similar to (1). It appeared to be largely crystalline. containing from 60-73 per cent. of Sióg. Then, coming Plagioclase most conspicuous, but also augite, olivine, to the group of rocks which, as containing the mineral and magnetite.

cossyrite (rather, ænigmatite) and much soda and I have not seen the specimens, but the descriptions iron, he distinguishes by the name of "

“Pantellerites accord well with those given above for the outer and (which rocks form the greater part of the surface of the inner material of the recent bombs. As will be seen island), he finds that the older ones contain about 70 per below, they also agree well enough chemically.

cent. of silica, and the younger only 67 per cent., thus

heralding the outburst of basic rocks (lavas and scoria) Description of certain Basic Scoria from the Island of above), which form the most recent rocks of the island,

containing some 49-50 per cent of silica (see table Pantelleria.

and are confined to the north-west part of it. I did not obtain specimens of the plagioclase-basalts That we should find a still further decrease of Sio, to from the Cuddie Monti and S. Marco, analyzed by 46-40 per cent. is, so far, interesting. I have not come Foerstner (see below), but I have basic scoriæ from across an analysis of any very recent lava of Etna to different localities in the north-west part of the island. know whether the lava of that district shows any tendSpecimens from Cuddie Brucciate, while differing in ency in the same direction. structure, agree mineralogically with the recent ejecta, 'In conclusion, I must express my thanks to Prof. Judd, having crystals of triclinic felspar, olivine, and augite, to whom I am indebted for reference to the authors set in a glassy or opaque black ground, as the case quoted, and for loan of papers. may be.

December 26, 1891.

GERARD W. BUTLER. Further, some very black and rough specimens, from a small patch of basic scoriæ north-east of the Bagno del

ANALYSIS OF VOLCANIC BOMB, PANTELLERIA, OCTOBER 1891. Aqua, not only agree mineralogically, but are in texture Percentage Composition of Washed Powder, dried at 120° C. not unlike the intermediate portion of the bomb described above.

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A Comparison, as to Chemical Constitution, of the Pro.

ducts of the Recent Eruption with those of Graham's Island, and certain Lavas of Pantelleria, Etna, and Vesuvius.

In the following table the iron oxides are taken together. In the case of the Etna lava of 1865, the analyses by Fuchs and Silvestri disagree as to the proportions of FeO and Fe,Oz.

The results in the first four columns are from a table in Foerstner's paper (loc. cit.). For the fifth column I have to thank Mr. Geo. H. Perry, who has made an analysis of part of the large mass above mentioned, and also Prof. Thorpe, F.R.S., who kindly permitted the work to be done in the laboratory of the Royal College of Science. Mr. Perry's analysis will be found in full below.

This table speaks for itself. There is in the recent bomb a little less silica and a little more alumina than in the specimens from Graham's Isle, Etna, and Pantelleria, while the percentages agree with those in the specimen from Vesuvius.

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tells us,


absolutely pure metal could not be obtained ; manganese,

for instance, seems always present, even after repeated PERIODIC LAW.

purifications. IN N the course of a prolonged series of spectroscopic ob- This led to a study of the periodic law as enunciated by servations on iron containing to carbon, 'o8 sulphur,

Mr. Crookes in his address on the genesis of the elements. *070 phosphorus, and about it per cent. of manganese, He advances the rational hypothesis that atoms are and based on the previous investigations of Mr. Lockyer formed from the original protyle or fire mist ; next, by a on the iron spectrum at varying temperatures, I noted

series of atomic condensations, due to successive coolings, some results summarized as follows:

the elements are formed. Mr. Lockyer, by somewhat dif(1) Iron heated in vacuo evolves a vapour showing the ferent methods of research, appears to have come to the H spectrum ; in addition, other lines are sometimes same conclusion-viz. that temperature governs all ; and visible.

as the result of a long series of spectroscopic (2) I have found that iron kept in a vacuum slowly

observations," that an element is a very complex thing, evolves H at a temperature not exceeding 70°–80° ; this broken up-at higher temperatures-into simpler things. continued for six months. Further, on applying heat, I

Mr. Crookes, by a careful study of the periodic law, suphave observed a condensed sublimate at the sealed cold plemented by spectroscopic work, shows how elements end of the tube.

may be built up. Mr. Lockyer, pursuing the opposite Heated iron known to contain small quantities of some method, viz. by a study of the breaking up of the so-called of the more fusible metals evolves these bodies, and vice elements, and registering the results by means of the T'ersâ absorbs them. Exhausted heated iron also absorbs spectroscope, appears to have experimentally proved the H in the same way, and most rapidly at an intense heat same thing. approximating to fusion.

It is quite obvious that an absolutely pure element can (3) Oniron being heated in the blow-pipe flame through only exist at a given temperature ; any deviation from this which the spark was passing, lines were detected in the --the critical temperature-must favour partial dissociaflame apart from the iron,

tion, and in this way it undergoes changes which may (4) On heating iron electrodes, “varying the tension of veil its true atomic weight. As Mr. Crookes puts it, “ of the spark, also the flame temperature,” according to a given mass of atoms, only a few may have the true methods elsewhere given, I found it possible to obtain atomic weight, the others slightly varying from it.” Grantiron spectra, varying roughly in accordance with the heat ing a variation of atomic weight in the element for the of the fame and spark tension. Three nearly distinct same reason, there may be a shifting of its spectral lines. spectra have been observed :-(1) Lowest heat, a nearly I submit also that the discrepancies in the position of pure manganese spectrum. (2) Higher heat, manganese certain spectral lines may be due to divergence from the lines; other long lines appear, also the beginnings of a critical temperature, and not observational errors.1 short-line spectrum. (3) Highest heat, a complete iron There appears, therefore, to be no necessity for the spectrum.

use of such phrases as chemical affinity, cohesive force, As regards the first spectrum, manganese has been &c.: heat energy and the universal law of gravitation identified by the ordinary method of chemical analysis. seem the only factors controlling the genesis of the The second group of long lines the chemist would say elements-can" we also say the genesis of known were due to the presence of some body not identical with chemical compounds ? either iron or manganese, but this problematic body has We cannot well say how far the physical properties of not been identified or isolated; the proof is wanting, such a metal as iron are modified by temperature although it is a product, or function, of temperature, just variations; yet we have seen that something like disas is the first or manganese spectrum. This spectrum sociation is going on at 70°-80°, and that at a moderate may be due to dissociation of iron, and not to the vapor- heat this is accentuated; whilst at high temperatures the. ization of a foreign constituent. It is probable that iron spectrum of iron affords ample proof that such is the case. can be roughly split up into two bodies, one of which is Experiments have been made showing that even at the more volatile than the other, and that the relative quan- bare fusion-point of iron matter is volatilized ; and at the tity of each present may not always be the same. At abnormally high temperature of the Bessemer blowany rate, it appears that by the simple heating of crude “melting up lumps of cold steel plunged in, and weighing iron its composition may be sensibly modified, and that, 2 or more cwt, like wax”—it is admitted that iron as even at a temperature as low as 70°-80°, slow dissociation such is vaporized. It seems therefore, on the whole, that is going on, manifested by the evolution of hydrogen ; and even a stable body like iron, when heated, gives results this continues, the rate of dissociation apparently broadly according with the periodic law; and as regards other corresponding to the heat applied. It follows that in bodies, from ice upwards, we do not need to be informed actual practice the chemical composition of iron may thus that evaporation (dissociation) is constantly going on. be altered, such changes being probably so minute as to It may not, however, be so well known that" on heatescape recognition.

ing some of the more fusible metals in a vacuum," it is These researches were made with the sole object of possible to obtain almost invisible vapours, some of which utilizing the spectroscope as an aid to the ordinary iron occludes or absorbs just as it does the gases hydrogen chemical analysis of iron, my previous experience having and possibly carbon monoxide. taught me that an extension of the usual methods was Referring to the No. 2 spectrum indicating the probable imperatively required. It was thought that by the existence of an intermediate body betwixt iron and manspectroscopic method some body or bodies as yet un- ganese, not yet isolated, but which, nevertheless, is a recognized might be found ; in other words, I searched product or function of the temperature, just as manganese for so-called impurities with but scant success.

is; the supposition that this body is a constituent of iron Finally, I was forced to admit that I had exhausted the acquires force from the fact that recently it has been purely analytical part of the inquiry, and must seek for shown that iron may be capable of assuming two formsthe solution of the many discrepancies observed in the the one termed a, or soft iron; the other B, or hard iron. behaviour of iron and steel, and not comparable with its

Or, possibly, at a given temperature a vapour may be evolved from one chemical composition as determined by ordinary analysis. body so nearly approximating in compo-ition to that of another, the latter Nothing was left for further study, with the exception of not necessarily at the same temperature, as to be almost undistinguishable the metal itself. It may be remarked, however, that

from the other by the ordinary method of micrometric measurement. The same difficulty in another form occurs in ordinary chemical work : bodies

are so closely allied in some instances as to render their separation and Suggested by Mr. Lockyer.

identification very difficult.


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