a A a st nt ein ia Pe LEER I... Wilco JAR 11 1889 & < Prusonian pere® PROCEEDINGS _ OF THE ROYAL SOCIETY OF LONDON. From April 12, 1888, to June 21, 1888. VOL, ALY... : LONDON: HARRISON AND SONS, ST. MARTIN’S LANE, Printers in Ordinary to Her Majesty. MDCCCLXXXYIII. HARRISON AND SONS, PR ? oe eA CUMTAM. TS, 2208 (ia * CONTENTS. VOL. XLIV. No. 266.—April 12, 1888. Page Tae Baxerian Lecrure.—Suggestions on the Classification of the various Species of Heavenly Bodies. A Report to the Solar Physics Committee. Communicated at the request of the Committee. By J. Peememamametever, W.S, (Plate 1)...,.....-.scscsnecceopereorsnssencsanecer sosocsssssosensarers 1 TN TNE oe fons sccscodertecarsacccesdsscax’ acovesucccnstcovdeceeus socio theo 5 are 93 No. 267.—April 19, 1888. The Radio-Micrometer. By ©. V. Boys, A.R.S.M. ...,..ccssescsccssstecsooes senate: 96 On Hamilton’s Numbers. Part II. By J. J. Sylvester, D.C.L., F.B.S., Savilian Professor of Geometry in the University of Oxford, and James FPA, MA Carta. ......seesesnescestensssssecssassversencnvescersnsnasee cescaccessoserecses | DO Hydraulic Problems on the Cross-sections of Pipes and Channels. ‘Henry Hennessy, F.R.S., Professor of Applied Mathematics and Mechanism in the Royal College of Science for Ireland —.....c..sueseseeseseee 101 On the Heating Effects of Electric Currents. No. III. By W. H. Feet OMB re tee Aes 0k ce ict coc tcwctoaesneessavassaccacdeos odes sdestseuscuatigaceouseeteatt sees 109 On the Compounds of Ammonia with Selenium Dioxide. By Sir Charles A. Cameron, V.P.I.C., F.R.C.S.1., and John Macallan, F.I.C.. eelI2 On the Logarithmic Law of Atomic ganar ts G. J ohnstone hein MPA.) D.8¢.5 FR.S. . ee phlS tae aces paces nennins sacs hesnepiinnnddencilonensobianes See pase ee agente i April 26, 1888. On the Coagulation of the Blood. Preliminary Communication. By W. D. Halliburton, M.D., B.Sc., Assistant Professor of ET Oe University College, ‘London On the Development of the Electric Organ of Raza batis. By J. C. Ewart, M.D., Regius Professor of Natural History, University of Edinburgh Iv On the Occurrence of Aluminium in certain Vascular Cryptogams. By A, Hi. Church, M.A., FCS. cccsccecssesteccesoeeseseesenestec eee a On the Nature and Limits of Reptilian Character in Mammalian Teeth. By H. G. Seeley, F.R.S., Professor of Geography in King’s College, TrOMOD o.....s.ceessseecenoceececeabvestensedd obeonllvdeone dhee.e IV. Tables— A. Table of the specific differences in Group Ti Seee eae eeeer eee B. Table showing the stars in Dunér’s catalogue arranged in species .. Part V. THE CAavUsE OF VARIABILITY IN Groups I anp II. I. General views on variability .. 0:0 .= ¢sic0 «© +e bm = oles ie aie annie ene nnete oo I}. On the variability im ‘Group Es...) 2. eee eee BOS voce tat aie III. On the variability in Group II. ek ete cieteeee 3 The frequent occurrence of cartilage’ in Group 1 Table of variables. . wt G Alee 0's Sieh ape eet Se Secs ae How the difficulty o comlie variability on Newton’s view is got over in TMUTIE | isle) ses bk db aie es 6-50 ete he eases of small ange oss we fea 50. 80 ow tase ta alee Study of light curves. . a6 4 6 05. 0 bi alei w ameve ee eka 2 eee ee Double ‘stars 0.0.06 ke oe ec ea ee be ee oe) ee oe elena aoa Conclusion ....... van ee ce 0 alee 00 Ce a6 8 a ons © am wie fe) allen tele nerr [ Received March 21, 1888. ] Parr J.—PROBABLE ORIGIN OF SOME OF THE GROUPS. I. Nebulee. In a paper communicated to the Royal Society on November 15th, 1887, I showed that the nebule are composed of sparse meteorites, the collisions of which bring about a rise of temperature sufficient to render luminous one of their chief constituents—magnesium. This conclusion was arrived at from the facts that the chief nebula lines are coincident in position with the fluting and lines visible in the — bunsen burner when magnesium is introduced, and that the fluting is ; —- 1888. | of the various Species of Heavenly Bodies. 3 far brighter at that temperature than almost any other spectral line or fluting of any element whatever. I suggested that the association or non-association of hydrogen lines with the lines due to the olivine constituents of the meteorites might be an indication of the greater or less sparseness of the swarm, the greatest sparseness being the condition defining fewest colli- sions, and therefore one least likely toshow hydrogen. This sugges- tion was made partly because observations of comets and laboratory work have abundantly shown that great liability to collision in the one case, and increase of temperature in the other, are accompanied by the appearance of the carbon spectrum instead of the hydrogen ‘spectrum. The now demonstrated meteoric origin of these celestial bodies renders it needful to discuss the question in somewhat greater detail, with a view to classification ; and to do this thoroughly it is requisite that we should study the rich store of facts which chiefly Sir William Herschel’s labours have placed before us regarding the various forms of nebule, in order to ascertain what light, if any, the new view throws on their development. To do this the treatment must be vastly ate ent from that—the only one we can pursue—utilised in the case of the stars, the images of all, or nearly all, of which appear to us as points of light more or less minute; while, in the case of the nebule, forms a the most: definite and, in many cases, of the most fantastic kind, have been long recognised as among their chief characteristics. It will at once be evident that since the luminosity of the meteorites depends upon collisions, the light from them, and from the glow of the gases produced from them, can only come from those parts of a -meteor-swarm in which collisions are going on. Visibility is not the only criterion of the existence of matter in space; dark bodies may exist in all parts of space, but visibility in any part of the heavens means, not only matter, but collisions, or the radiation of a mass of vapour produced at some time or other by collisions. The appear- ances which these bodies present to us may bear little relation to their actual form, but may represent merely sur rfaces, or loci of disturbance. It seemed proper, then, that I should seek to determine whether the view I have put forward explains the phenomena as satisfactorily as they have been explained by old ones, and, whether, indeed, it can go further and make some points clear which before were dark. To do this it is not necessary in the present paper to dwell at any great length either on those appearances which were termed nebu- losities by Sir William Herschel or on irregular nebule generally ; but it must be remarked that the very great extension of the former —which there is little reason to doubt will be vastly increased by B 2 4 Mr. J. N. Lockyer. On the Classification [Apr. 12, increase of optical power and improvement in observing conditions and stations—may be held to strengthen the view that space is really a meteoritic plenum, while the forms indicate motions and crossings and interpenetrations of streams or sheets, the brighter portions being due to a greater number of collisions per unit volume. From this point of view it is also possible that many stars, instead of being true condensed swarms due to the nebulous development to which we have referred, are simply appearances produced by the intersection of streams of meteorites. They are, then, referable to an intensification of the conditions which gave rise to the brighter appearances recorded by Herschel here and there in his diffused nebulosities. The nebulous appendages sometimes seen in connexion with stars strengthen this view. When we come to the more regular forms we find that they may be generalised into three groups, according as the formative action seems working towards a centre; round a centre in a plane or nearly so; or in one directiononly. As a result we have globular, spheroidal, and cometic nebulez. I propose to deal with each in turn. Globular Nebule. The remarkable appearance presented by the so-called planetary nebule requires that I should refer to them in some detail. Sir William Herschel does not describe them at any great length, but in his paper on ‘‘ Nebulous Stars” he alludes to the planetary nebulosity which in many cases is accompanied by a star in the centre, and finally comes to the conclusion that ‘‘the nebulosity about the star is not of a starry nature” (‘ Phil. Trans.,’ vol. 81, 1791, p. 73.) Sir John Herschel, in his valuable memoir published in ‘ Phil. Trans.,’ 1883, describes them as “ hollow shells” (p. 500). It was so difficult to explain anything like their appearance by ordinary ideas of stellar condensation that Arago, as quoted by Nichol (‘ Architec- ture of the Heavens,’ p. 86), abandoning altogether the idea that they represented clusters of stars or partook in any wise of a stellar con- stitution, imagined them as hollow spherical envelopes, in substance cloudy and opaque, or rather semi-transparent; a brilliant body invisible in the centre illuminating this spherical film, so that it was made visible by virtue of light coming through it and scattered by reflection from its atoms or molecules. Lord Rosse (‘ Phil. Trans.,’ vol. 140, 1850, p. 507) records that nearly all the planetary nebule which he had observed up to that time had been found to be perforated. In only one case was a perfo- ration not detected, but in this anse were observed, introducing into the subject for the first time the idea of nebulous bodies resembling to a certain extent the planet Saturn. But Lord Rosse, although he thus disposed of the idea of Arago, still considered that the annular 1888.] of the various Species of Heavenly Bodies. By) nebule were really hollow shells, the perforation indicating an appa- rently transparent centre. Huggins and Miller subsequently suggested that the phenomena represented by the planetary nebulz might be explained without _ reference to the supposition of a shell (or a flat disk) if we consider them to be masses of glowing gas, the whole mass of the gas being incandescent, so that only a luminous surface would be visible (‘ Phil. Trans,’ vol. 154, 1864, p. 442). It will be seen that all these hypotheses are mutually destructive. but it is right that I should state, in referring to the last one, that fie demonstration that these bodies are not masses of glowing gas merely has been rendered possible by observations of spectra which were not available to Dr. Huggins when his important discovery of the bright- line spectrum of nebule was given to the world. It remains, then, to see whether the meteoritic hypothesis can explain these appearances when it is acknowledged that all the prior ones have broken down. If we for the sake of the greatest simplicity consider a swarm of meteorites at rest, and then assume that others from without approach it from all directions, their previous paths being deflected, the question arises whether there will not be at some distance from the centre of the swarm a region in which collisions will be most valid. If we can answer this question in the affirmative, it will follow that some of the meteorites arrested here will begin to move in almost circular orbits round the common centre of gravity. The major axes of these orbits may be assumed to be not very diverse, and we may further assume that, to begin with, one set will _preponderate over the rest. Their elliptic paths may throw the peri- astron passage to a considerable distance from the common centre of gravity; and if we assume that the meteorites with this common mean distance are moving in all planes, and that some are direct and some retrograde, there will be a shell in which more collisions will take place than elsewhere. Now, this collision surface will be practically the only thing visible, and will present to us the exact and hitherto wnex- plained appearance of a planetary nebula—a body of the same intensity of luminosity at its edge and centre—thus putting on an- almost phos- _phorescent appearance. ) If the collision region has any great thickness, the centre should appear dimmer than the portion nearer the edge. Such a collision surface, as I use the term, is presented to us during a meteoric dispiay by the upper part of our atmosphere. I append a diagram, Fig. 1, which shows how, if we thus assume movement round a common centre of gravity in a mass of meteorites, one of the conditions of movement being that the peri- astron distance shall be somewhat considerable, the mechanism which produces the appearance of a planetary nebula is at once made appa- 6 Mr. J. N. Lockyer. On the Classification [Apr. 12, Fie. 1.—Suggested origin of the appearance presented by a planetary nebula. The luminosity is due to the collisions occurring along the sphere of intersection. of the elliptic orbits of the meteorites. The left-hand diagram is a cross- section of the meteoric system, and the right-hand one shows the appearance of the collision-shell as seen from a point outside. rent. The diagram shows the appearance on the supposition that the conditions of all the orbits with reference to the major axis shall be nearly identical, but the appearances would not be very greatly altered if we take the more probable case in which there will be plus and minus values. Globular Nebule showing Condensation until finally a Nebulous Star is reached. If we grant the initial condition of the formation of a collision- shell, we can not only explain the appearances put on by planetary nebule, buta continuation of the same line of thought readily explains. those various other classes to which Herschel has referred, in which condensations are brought about, either by a gradual condensation towards the centre, or by what may be termed successive jumps. These condensations doubtless are among the earliest stages of nebular development. To explain these forms we have only to consider what will happen to the meteorites which undergo collision in the first shell. They will necessarily start in new orbits, and it is suggested that an interior collision-shell will in this way be formed. In consequence of the collisions the orbits will have a tendency to get more and more elliptic, while the pericentric distance will at the same time be reduced; the swarm will, in consequence of this action, 1888. ] of the various Species of Heavenly Bodies. 7 Fig. 2.--Suggestion as to the origin of a globular nebula with a brighter central portion. As in the former case, the luminosity of the fainter portion is due to the collisions which occur along the sphere of intersection represented by the larger circle. After collision the meteorites will travel in new orbits, and there will be an additional sphere of intersection, represented by the smaller circle. The left-hand diagram is a cross-section, and the right-hand one represents the appearance of the two collision-shells as seen from a point outside. gradually brighten towards the centre through collisions being possible nearer the centre, and ultimately we shall have nebule with a distinct nucleus, the nucleus then representing the locus of most collisions. This brightness may be sudden in certain spherical surfaces, or quite gradual, according to the collision conditions in each swarm. The final stage will be the formation of a nebulous star. Effects of Subsequent Rotation.—Spheroidal Nebule. In such meteor-swarms as those we have considered, it must be that rotation is, sooner or later, set up. Otherwise it would be impossible to account for the spheroidal nebule at all. I am aware that in Newton’s opinion the cause of this rotation was not mechanical, but the moment we assume a meteoric origin of these globular clusters it is straining the facts to assume that the intake will be exactly the same at all points, and the moment the bombardment is more or less localised, rotation must follow sooner or later. Sir William Herschel, in his paper of 1811 (p. 319), says, “‘ If we consider this matter in a general light, it appears that every figure which is not already globu- lar must have eccentric nebulous matter, which, in its endeavour 8 Mr. J. N. Lockyer. On the Classification ([Apr. 12, Fie. 3.—Suggestion as to the origin of a nebulous star. The orbits of the inner set of meteorites are very elliptic, so that the shell of intersection appears almost as a point. As in the previous cases, the left-hand diagram represents the meteoric systems in section, and the right-hand one the appearance from a point outside. to come to the centre, will either dislodge some nebulosity which is already deposited; or slide upon it sideways, and in both cases produce a circular motion; so that, in fact, we can hardly suppose a possible production of a globular form without a subsequent revolution of nebulous matter, which in the end may settle in a regular rotation about some fixed axis.” Given, then, a globular swarm with a rotation around an axis, we have to discuss the phenomena produced by collisions under a new set of circumstances. Here at once we have to account for the fact that the nearly spherical forms are very short-lived, for they are very rare; we seem to jump, as it were, from globes to very extended spheroids. If it be conceded that from the above considerations we are justified in supposing that the elliptic and other spheroidal nebule really repre- sent a higher stage of evolution than those presented to us by the globular form, it is clear that on the meteoritic hypothesis the greater part of the phenomena will represent to us what happens to such a system under the condition of.a continuous bombardment of meteor- ites from without. So soon as we have a minor axis, there will at first be most colli- sions caused by the movements of meteors, the paths of which are most nearly parallel to it; the result of this will be that the equatorial plane will be intensified, and then, later on, if we conceive the system 1888.] of the various Species of Heavenly Bodies. 9 as a very extended spheroid, it is obvious that meteorites approaching it in directions parallel to its minor axis will have fewer chances of collisions than those which approach it, from whatever azimuth, in what we may term the equatorial plane. These evidently, at all events if they enter the system in any quantity, will do for the equatorial plane exactly what their fellows were supposed to do for the section in fig. 1, and we shall have on the general back- ground of the symmetrically rotating nebula, which may almost be invisible in consequence of its constituent meteorites all travelling the same way and with nearly equal velocities, curves indicating the regions along which the entrance of the new swarm is interfering with the movements of the old one; if they enter in excess from any direction, we shall have broken rings or spirals. This was suggested in my last paper. Various segments of rings will indicate the regions where most collisions are possible, and the absence of luminosity in the centre by no means demonstrates the absence of meteorites there. Researches by Lord Rosse and others have given us forms of nebule which may be termed sigmoid and Saturnine, and these suggest that they and the elliptical nebule themselves are really pro- ‘duced by the rotation of what was at first a globular rotating swarm of meteorites, and that in these later revelations we pick up those forms which are produced by the continued flattening of the sphere into a spheroid under the meteoric conditions stated. It is worthy of remark that all the forms taken on by the so-called elliptic nebule described by the two Herschels, and by the spiral, sigmoid, and Saturnine forms which have been added to them by the labours of Lord Rosse and others, are recalled in the most striking manner by the ball of oil in Plateau’s experiment, when rotations of different velocities are imparted to it. The Saturnine form may, indeed, in some cases represent either the first or last stages in this period of the evolutionary process. I say may represent, in consequence of the extreme difficulty in making the observations so that in the early stages a spherical nebula, beginning to change into a spheroid, may have its real spheroidal figure cloaked by various conditions of illumination. The true Saturnine form must, as in the case of Saturn itself, represent one of the latest forms in the meteor-swarm, because, if it be not continually fed from without, collisions must sooner or later bring all the members of the swarm to the centre of figure. Cometic Nebule. I do not know that any explanation has, so far, been suggested as to the origin of these curious forms, which were first figured by Sir William Herschel, and of which a number have recently been 10 Mr. J. N. Lockyer. On the Classification [Apr. 12, observed in the southern hemisphere (‘ Observations of the Southern Nebule, made with the Great Melbourne Telescope,’ Part I). It is clear that in them the conditions are widely different from those hitherto considered in this paper. I think that the meteoritic hypo- thesis satisfactorily explains them, on the supposition that we have either a very condensed swarm moving at a very high velocity through a sheet of meteorites at rest, or the swarm at rest surrounded by a sheet all moving in the same direction. It is a question of rela- tive velocity. If we consider the former case, it is clear that the collision region will be in the rear of the swarm, that the collisions will be due to the convergence of the members of the sheet due to the gravity of the swarm, and that the collision region will spread out like a fan behind the swarm. The angle of the fan, and the distance to which the collisions are valid, will depend upon the velocity of the condensed swarm. [Received March 26, 1888. ] II. Stars with Bright Lines or Flutings. I pointed out in my last paper that those stars in the spectra of which bright lines had been observed were in all probability the first result of nebulous condensation, both their continuous spectrum and that of the surrounding vapour being produced by a slightly higher temperature than that observed in nebule in which similar though not identical phenomena are observed. I have recently continued my inquiries on this point; and I may say that all I have recently learned has confirmed the conclusions I drew in my last paper, while many of the difficulties have disappeared. Before I refer to these inquiries, however, it is necessary to clear the ground by referring to the old view regarding the origin of bright lines in stellar spectra, and to the question of hydrogen. went to the Old View by which it was supposed some of the Bright- line Phenomena might be accounted for. In the views which, some years ago, were advanced by myself and others, to account for the bright lines seen in some of the “stars’’ to which reference has been made, the analogy on which they were based was founded on solar phenomena; the “stars” in question being sup- posed to be represented in structure by our central luminary. The main constituent of the solar atmosphere outside the photosphere is hydrogen, and it was precisely this substance which was chiefly revealed by these stellar observations and in the Novas, in which cases it was sometimes predominant. A tremendous development of -1888.] . of the various Species of Heavenly Bodies. 11 an atmosphere like that of the sun seemed to supply the explanation - of the phenomena. Acting on this view in 1878,* I attempted to catch these chromo- spheric lines in a Lyre, abandoning the use of a cylindrical lens in front of the slit with this object in view. Further, it was quite clear that if such gigantic supraphotospheric atmospheres existed, their bright lines might much modify their real absorption spectra; even “ worlds without hydrogen” might be thus explained without supposing a lusus natwre, and so I explained them. That this view is untenable, as I now believe, and that it is unneces- sary, will, I think, be seen from what follows. Be [Apr cation if On the Class i | hs P. aes o fe) a Mr. J.N. 1888. | of the various Species of Heavenly Bodies. 63 being the brightest (fig. 14). The lines, flutings, or bands in the lowest horizon, in the case of each element, are those seen at the lowest temperatures, and are the first to appear when only a small quantity of substance is present. Those in the upper horizons are the faintest, and are only seen when the tempera- ture is increased, or a considerable amount of the substance is volatilised. The map shows that if there are any indications of magnesium, for instance, in bodies at low temperatures, the fluting at 500 will be seen, possibly without the other fluting or lines. The first indications of manganese will be the fluting at 558, and so on. Again, on account of the masking effect of the spectrum of one element upon that of another, we may sometimes have an element indicated in a star spectrum, not by the brightest band or fluting in its spectrum, but by the second or even third in brightness; this, of course, only occurs when the darkest band falls on one of the brightest futings of carbon, or upon a dark band in the spectrum of some other element. In the former case the dark band will be cancelled or masked; in the latter case the two absorptions will be added together, and form a darker band of a different shape. The Question of Masking. If we consider the masking effects of the bright carbon flutings upon the absorption spectrum of each of the elements which, accord- ing to the results obtained, enter into the formation of Dunér’s bands, we have the following as the main results :— : Magnesium.—There are two flutings of magnesium to be considered, the brightest at 500 and the other at 521. In the earlier stages of Dunér’s stars only the fainter one at 521 is visible, but the absence of the brightest at 500 is accounted for by the masking effect of the bright carbon fluting starting at 517. As the carbon fades, the 517 flating narrows and the absorption of magnesium 500 becomes evident. Manganese.—The two chief flutings of manganese are at 558 and 586, the former being the brightest fluting in the spectrum. The second fluting is seen in all of Dunér’s stars. The first fluting, 558, however, does not appear as an absorption fluting until the radiation fluting of carbon starting at 564 has narrowed sufficiently to unmask it. It is thus easy to understand why, in some stars, there should be the second fluting of manganese without the first. Bariwm.—The spectrum of barium consists of a set of flutings ex- tending the whole length of the spectrum, and standing out on this as a background are three bright bands; the brightest band is at 915, the second is at 525, and the third, a broader band, is about 485. The second band is recorded as an absorption band in Dunér’s stars, the apparent absence of the first band being due to the masking Mr. J. N. Lockyer. On the Classification [Apr. 12, ABSORPTION. RADIATION. ABSORPTION. RADIATION ABSORPTION. Zz a ES < A <= o- OF ECIES 2 SPECIES .S*. SPECIES 5S HOT CARBON. MAGNESIUM, MANGANESE. RESULT , HOT CARBON. MAGNESIUM, MANGANESE. RESULT, HOT CARBON. MAGNE SIUM. MANGANESE. RESULT, Fig. 15.—Diagram showing the effects of variations in width of the flutings of carbon upon the integrated spectra of carbon radiation and magnesium and manganese absorption, as they appear in different species of bodies of Group II. 1888.] of _the various Species of Heavenly Bodies. 65 effect of the bright carbon at 517. The third band at 485 probably forms a portion of band 9. A fourth band, at 533, and the three brightest flutings at 602, 635, and 648 are also seen in « Orionis. Chromium.—tThe flutings of chromium do not form portions of the ten principal bands of Dunér, but the brightest are seen in a Orionis. The brightest fluting is at 580, and this forms band 1; the second, at 557, is masked by the manganese fluting at 558, and the third at 536 is seen as line 2. The chromium triplet about 520, which is visible in the bunsen, is seen as line 3. Bismuth.—The brightest fluting of bismuth is at 620, the second is at 571, the third at 602, and the fourth is at 646. The first is masked by the iron fluting at 615, the second is seen in e Orionis as band 2 (570—577). The points I consider as most firmly established are the masking effects of the bright carbon flutings and the possibility of the demon- stration of the existence of some of the flutings in the spectrum by this means, if there were no other. There are two chief cases, the masking of the “nebula” fluting 500 by the bright carbon fluting with its brightest less refrangible edge at 517, and that of the strongest fluting of Mn= Mn (1) 4558, by the other carbon fluting with its brightest edge at 564. I have little doubt that in some quarters my anxiety not to be content to refer to the second fluting of Mn without being able to explain the absence of the first one, will be considered thrown away, as it is so easy to ascribe any non-understood and therefore “abnormal” spectrum to unknown physical laws; but when a special research had shown me that at all temperatures at which the flutings of manganese are seen at all, the one at 558 retained its supremacy, I felt myself quite justified in ascribing its absence in species 1—4 to the cause I have assigned, the more especially as the Mg flating which is visible even in the nebula followed suit. The Characteristics of the Various Species. I append the followmg remarks and references to the number of the bodies in Dunér’s catalogue, in which the specific differences come out most strongly, to the tabular statement. I also refer to some difficulties. Sp. 1. The characteristic here is the almost cometary condition. All three bright carbon futings generally seen in comets are visible; 474 standing out beyond the end of the dull blue continuous spectrum of the meteorites, 516 masking Mg 500, and 564 masking Mn(1) 558. The bands visible in the spectra of bodies belonging to this species will therefore be Mn(2) 586, and Mg(2) 521; band 9 will be so wide and pale that it would most likely escape detection. It is very doubtful whether any of the bodies the spectra of which have hitherto been recorded can be classed in this species, but laboratory VOL. XLIY. F 66 Mr. J. N. Lockyer. On the Classification [Apr. 12, work assuredly points to their existence; it will therefore be ex- tremely interesting if future observations result in their discovery. It is possible, however, that No. 150 of Dunér’s list belongs to this species, but the details are insufficient to say with certainty. His description is as follows:—‘‘150. Il me parait y avoir une bande étroite dans le rouge, et une plus large dans le vert’ (p. 55). Sp. 2. Characteristics: appearance of Fe. The number of bands now visible is three—namely, 2, 3, and 7. The iron comes out as a result of the increased temperature. Mg(1) and Mn(1) are still masked by the bright carbon flutings, and there is still insufficient luminosity to make the apparent absorption-band 9 dark enough to be noticed. Sp. 3. Characteristics: appearance of Mg 500, which has pre- viously been masked by the carbon bright flutings 517. 7 and 8 are now the darkest band in the spectrum. Sp. 4. Characteristics : appearance of Pb(1) 546, te, band 5. This, if present in the earlier species at all, would be masked by the bright carbon at 564. Sp. 5. Characteristics: Mn(1) is now unmasked. The bands now visible are 2, 3, 4, 5, 7, and 8, the two latter still being the widest and darkest, because they are essentially low-temperature pheno- mena, } Sp. 6. Characteristics: band 6, 7.e., Ba(2), 525, is now added. The first band of Ba at 515 is masked by the bright carbon at 517. The bands now visible are 2—8, 7 and 8 still being widest and darkest. They will all be pretty wide, and they will be dark because the con- tinuous spectrum will be feebly developed. Sp. 7. Characteristics: appearance of band 9. This, which has been already specially referred to, has been too wide and pale to be observed in the earlier species. Its present appearance is due to the narrowing and brightening of the carbon at 474 and the brightening of the continuous spectrum, the result being a greater contrast. Bands 7 and 8 still retain their supremacy, but all the bands will be moderately wide and dark. Sp. 8. Characteristics: all the bands 2—-9 are more prominent, so that 7 and 8 have almost lost their supremacy. Sp. 9. Characteristics : appearance of band 1, fie origin of which has not yet been determined. All the bands are well seen, and are moderately wide and dark. Sp. 10. Characteristics: appearance of band 10, and in some eases 11. These become visible on account of the brightening of the carbon B finting and the hydrocarbon fluting at 431. The spectrum is now at its greatest beauty, and is discontinuous. Sp. 11. Characteristics: the bands are now becoming wider, and 2 and 3 are gaining in supremacy; 7 and 8 become narrower on ~ : 4 LOCKYER. Prac. Roy. Soc., Vol. 44, Pl. J. ‘ t 31, are only CONT.SPEC. FIRST SPECIES » The carbon flutings The length of the continuous rbon fluting at 4 ‘LAST CARBON A FIRST a oa . fF , A LAST ns ain hydro ri 4 e 17 - « obable origin of the bands. Fe f HYDROCARBON Oo € fluting, and SrECIES "1 only a trac bon B > II, and the pr 3 D5 le rou pec ¥ ca t Ps Ny S las h ik of G le odie I ne I of t S flutings nar * > various specie ceradually narrow until, in t] | a ni the earbo Ss of the a a re ases pecies, and the spectr ok or present in species 8 to 12. t in the first Map showin $ PROBABLE ORIGIN OF BANDS), NUMBERS OF THE BANDS. DUNER'S MEAN ‘VALUES. are wide spectrum gradually inc . 16, 9 é ie ame a 1888.] —s_ of the various Species of Heavenly Bodies, 67 account of the increased temperature. 1 and 10 are only occasionally seen in this species. Sp. 12. Characteristics: with the expansion of the continuous spectrum towards the blue, band 9 becomes very narrow, and cannot be observed with certainty. The other bands, with the exception of 7 and 8, are becoming wider and paler, while 2 and 3 still gain in supremacy. Sp. 13. Characteristics: 9 has now entirely disappeared, 2 and 3 _ still retaining their supremacy. Sp. 14. Characteristics: all the bands are pale and narrow; 2 aa 3 will ‘stil be darkest, but the difference will not be so great as in the species preceding. Sp. 15. Characteristics: in ordinary members of this group, 2 and 3 now alone remain visible: they are wide, but feeble, as the contin- uous spectrum which has been rapidly developing during the last changes is now strong. [Apr. 12, Mr. J. N. Lockyer. On the Classification 68 ‘spusq sjtounqg ‘ssulyny uorydtosqy ‘MOGIvO JO SSUTIN] WOTyeIpey ‘TT dnowy ut soouoreziqy oytoodg—y 24%, oulox) | eu0xy) auo0x) (2) ast “c (73 euo4y) “cc ou04) 66 6c os eu0y ouos s qsowyly suvoddusicy ce aUOS JSOWLY 2 ig ouo4) SAVJS JSOFUOTAG oy} qnq solv so[tq [[@ Ul MOALR jy a Ae 26 SMOLLG \T SM OLLG NT “ ks suvodd vy i Surprq SUIpR Ay “ a“ ¥ Su014g a 6 a SUOPT A SUOPT AA SMOILB NT sudyIR(T - . Re moureu ATO A | MOTIBU A109 A a suvoddy - aa e opm pus TOMOUTVU Loyaep TINS as pure Loyysirg Ag us moareu A190 A 2 a6 SUOPl AA cc (75 ce SUIMOFT SIG Suto; STAY Suluegy stag yarep srvoddy puUB SUIMOAIVT | PUB SULMOLILNT | PUB SULMOATE NT 66 66 6c (75 LTg Aq poyseua eyed pus ‘yuosoad JT oped pur opr, | oped puv opty | opr Ar0 A “OT oe: “LTS PLY ; ——_—_—_—_—_--—_—- — — “T9V ane Oe ‘gq uogaey -oapAFT 'g 6 ‘OL “Vy uoqied “gotoedg 69 tes of Heavenly Bodies. of the various Spee 1888.] ON oN (srao1rg » UI yaep ATqrssod) O[GVIIvVA PUL qystaq ‘89K ON ON ON ON ON ot ON 80K es “SoUlT uosorpséy TIY JOU MA auo4y SuIpey quoserd TIW9 srvoddy ce SMOLIV NT mul pei Se a O81 so[eq qUIvT pus prorq AOA AAO NT ce sup AA en SUO YB (T “ec «¢ ejed pur uryy suvoddy quosqy ‘ON ce SM OL NT POTS rap ae SVE. sole qUIv] puv prorq AOA ALON a 6c be «sé SUOpI AA ee suoycvcy 66 ce 6 ered pure ur y, (2) 00 $ ouoKny qUIvE pUR UIILT, 6c Sov 73 66 66 eat PTA yrep ‘poysvuLu 6¢ 7 P99 Aq poysuun qnq “quosorg “(DU ~ ‘quoo—ssurny uorjdcosq y OU) JVUIGF PUB ULE T, «6 66 73 SULOPT AA. yarep suvodd y yrup savoddy ‘TI dnoay ui soouss9yiq, ogloodg—'y o[qvJ, ouoy) quyey puw UT, 6 so[tq suoyreqy cc ce suoyIUcy suvodd yz 9uoyx) JUrB} ple att, “ ce solv “ “ BMOLL NT “ce SsuOpT ttf sudylEcy 8 <12 290 P | 222 | R Sagittarii ...... is 12 270 / BRS VOTO se eaicc ss, - 78 <12 256 / 86 No. in -Dunér Cat. —————- 18 20° 29 SPA 141 158 166 184 196 217 221 239 293 ‘Mr. J. N. Lockyer. On the Classification [Apr. 12, 3. Bands wide and strong, especially 7 and 8. Name. Max. Min. Period. T APICHIS s,F 0 canes 8 9—10 324 iy: Deairieedc aie % ¢ 78 2B 326 S Canis Min...... A ran 33zZ I (CAnGriny is. 4a eG. 6 <1ll—12) 360 R Leonis Min..... 5 10 313 R Urs. Maj... .... 6 12 303 R Crateris........ >8 <9 160.? Ry COnviesa eae se Fh < fi-—jAs| 319 BR BoOtissiecs ys ee 6 12 223 NS. geno TEES Culene carats fenrsce 8 12—138 190 ? R Serpentis ....-. 5°6 sas! 5. < oad SP. T 61h. T 6r8-T 6&9. 08s. G OL8-¢ G08: G 61S. 8 0S. TT ZZL100-0 | 8010-0 Gs P06: T 028. T L96-% LVE-¥ 699-9 GGG. L a LV -OT ST- PL T8E100-0 | VPZETO-0 0€ E8P-% &LE-% 996-3 L99-¢ GGG. 8 9TP-6 TI8-6 99. ST PV. ST TO8100-0 | S8PIO-0 86 O&&-€ 681-& G96. 209. Z Lip. TT 69- OT 6: GT 6S: 8T VL: VG S1TPZ00- 0 810: 0 92 a 667- ¥ 008. 1 L98-¢ LZ- OT 0S: ST 90-L41 88: OT GL. VE SV. €& €9Z&00- 0 660: 0 VG ) L9P- 9 GLT-9 G69: L GL. PT GS -GS OS- 7G &6: VG 6¢-G& | 00-87 Gs9P00- 0 820: 0 66 > 6IP- 6 600: 6 6é- IL 0S. 16 PV. SE G4. GE 68. GE T8- Tg L6- 69 T&8900- 0 960-0 0G a O¢- FI 98. €T Lé- LT OL. &€ G6. 67 66. PS LE. 09 GL. 64 4. LOT 9TSOTO- O- 870-0 SI - GE: GG VE. 16 89.96 96. 0S 06-94 89-78 €4- &8 8- 261 8-G9L | T619TO-0 90-0 9T se 02-16 68-66 ST L8 G6. 14 G- LOT €-81I1 0-411 9-TAT 8. 1&6 | 4696d0-0 080: 0 VL = . eo) Ud ea : : : , ¢ : “HO AAe Fe 6481 =” Lorre CPOT = 9 | SPIS = 7 | OSLF = | 08ZS = M | ‘CLTS = | “S8SL = 8 FIC OL =? +e soyouy | DAS Ss “peoy “UL, "MOLT ‘plournerg | oaqig “to | ‘wunuTyR[g |‘wumrurun,y| ‘seddop ole ‘Iayourviqy | ‘ON Dee Ey Giphe =O ‘s]eLIoyepy. pu sezig SNOB A JO SOUTAA OST 04 potinber sorgdmy Ul quoIINy oY} SULMOYS 2[q%], 110 111 On the Heating Effects of Electric Currents. 1888.] A 0°60 O OO€ LI9&. 0 826-0 0266-0 9806: 0 98ST- 0 L8¥VT- 0 86FT-0 TOTT- 0 | LPs. 0 8STSs- 0 806-0 6961-0 L6V1-0 POVL- O PIPT-O. S60T- O L680. 0 CLz €0GE- 0 TO&e-O- TS86- 0 SPST. O POPT-O LTETt-0 LZET-O SG0T- 0 TP80-0 OSS 9866-0 LLOE- 0 8996-90 GoLl- 0 6081-0 82eL O LEZ1-0 8960-0 P8LO- 0 G66 0946. 0 SV8S- 0 LSbZ-O G6ST-0 OT6I- 0 CELT. 0 PVIL-O 9880-0 G610-0 006 €196- 0 6996-0 T6Z6- 0 PSPL-O 8211-0 8SOT-0 990T- O 9680: 0 9490.0 O8T 6286-0 SSPS-O 8SIIG-0 GLET-O €POT: O 8460: 0 9860-0 €9L0- 0 $690: 0 O9T 9416-0 EPCs. 0 LZe61-0 GSZT-0 PS60:0 G680- 0 6060. O 8690-0 6450: 0 OVI PIBT- O PE0G- O SPLT-O SSTT- 0 T980. 0 8080: 0 PI80-0 0€90- 0 9190-0 OZL 6ELT- 0 G6LL-O SPST-O 00T- 0 69L0- 0 GT40-0 0640. 0 8990-0 LS¥0- 0 OOT 169T-0 TZ9T: 0 SPV. O G¢60- 0 TIZ0: 0 £990-0 6490-0 0690: 0 9200-0 05 66PT- 0 PPSL- O PEEL-O P98O- O ¢90-0 9190-0 - 1690-0 180-0 P6E0-0 08 TZ§1-0 €TPT-O 0Z61-0 1640-0 TO90 O V9SO-0 8990-0 OPPO. O 0960-0 OL ZESL-0 GL4ZI-0 TOLT- 0 PILO-0 GPO: 0 600-0 6190-0 L6&0- 0 GZ60- 0 09 S60T- 0 661TL- O GL60- 0 6890: 0 O8PO- 0 OSPO. 0 PSPO- O 6280-0 8820-0 0g IZ0L-0 6SOT-O 6060-0 68-0-0 8PPO-0 O0ZPO- O €P0- 0 8&0. 0 8920: 0 cv PP60-0 €460-0 OF80: 0 SPSO-0 VIPO-0 8880. 0 1680-0 £0&0- 0 820-0 Ov P9800. 0 0680-0 6940-0 8670-0 6460-0 9960: 0 8960-0 LL60-0 1620-0 SE 6440-0 €080- 0 V690- 0 OPO. O VEO: 9 020.0 6360: 0 0SZ0- 0 020-0 O& 0690-0 TI40.0 PIY0-0 8680-0 6080: 0 860-0 9860-0 6660: 0 I810-0 G3 [690-0 €190-0 6620. 0 &PE0- 0 1920-0 GPO. O 9VG0- 0 1610-0 9ST0-0 0G T6P0- 0 9090-0 LE¥0-0 €820- 0 _ $1é0-0 GOGO -0 €060- 0 8910-0 6210-0 ST GZE0- 0 9860. 0 PEEO- 0 9160-0 PITO- O PEO. 0 SSTO.0 0610-0 8600-0 OT 9€Z0- 0 €PZO- O O10. 0 910. 0 POIO- 0 4600. 0 8600-0 9400- 0 6909-0 g 6060-0 O10. 0 1810-0 LTT0- 0 6800-0 P800- 0 V800- 0 ¢900. O €°00- 0 4 8YTO- 0 6410-0 6VTO- O L600: 0 PL00-0 6900: 0 0400-0 PS00- 0 PPOO -O & 8310-0 GE 10-0 €IT0-0 PLOO- 0 9500: 0 €S00- 0 €S00: 0 TFOO- 0 £00. 0 G T800- 0 £800-0 6400-0 LP00- O ¢€00: 0 ££00- 0 €£00-0 9200- 0 1600: 0 I ‘6LET = 2 ‘SISI = 2 ‘Grol = >? | ‘SPIE =? | ‘OC4F =P | “OSeG = P | “GLI = 7 | “G8GL = P | “PFSOT = 2 *peory ‘£OT[B peo] -ULy, ‘uly, | "uOdy ‘plourg | ‘oajig tog | ‘wnuyerg | ‘wniurn;y ‘soddoy ‘sorgd ue Ur guering "SATOUL UT LaJOULBI(T D “eiz (5) ms ‘yySueqg weary Jo quoting B Aq posny Og [[LM YOLYM S]VIAOVIY SNOIIBA JO SOITAA JO SLOJOWIVICG OY} UIAIS o[qQeVy, VOL. XLIV. 112. Sir Charles A. Cameron and Mr. J. Macallan. |Apr. 19, V. “On the Compounds of Ammonia with Selenium Dioxide.” By Sir CHARLES A. CAMERON, V.P.I.C., F.R.C.S.L, and JOHN MacauLaNn, F.LC. Communicated by Professor DEWAR, F.R.S. Received March 19, 1888. The following experiments were undertaken with the object of determining the action of ammonia upon selenium dioxide. They have resulted in the discovery of two new compounds, which, from what has been ascertained regarding their constitution, may, perhaps, be best designated by the term selenosamates or ammonium salts of an acid—selenosamic—yet to be isolated. Preparation of Neutral Ammonium Selenosamate. Ammonia, which had been carefully dried by passing through a series of potash tubes, was led into a solution of selenium dioxide in absolute alcohol. After being absorbed for some time, minute crystals commenced to deposit, and when complete precipitation had taken place, the liquid portion was filtered off, the crystals washed | with alcohol, and dried over sulphuric acid in a vacuum. The compound formed as above described is a deliquescent salt, which separates from its solution in alcoholic ammonia in minute, but very well-defined hexagonal prisms and pyramids—both forms often occurring in combination. It is a very unstable substance, con- tinuously liberating ammonia, and tending to the formation of a more stable acid salt. Some of the crystals which had been placed in a large stoppered bottle were found after some weeks to be entirely converted into large crystals of the acid salt. It also loses ammonia when treated with alcohol or water; and when its aqueous solution is evaporated in a vacuum, crystals of the acid salt remain. When heated, it is at once converted into the acid salt. On account of its instability, it is best prepared in a partial vacuum, and when dried placed in a stoppered bottle, which should be quite full and kept in a cool place. In this way it may be preserved of definite composition for a considerable time. It is with difficulty, and only partially, con- verted into ammonium selenite by the action of water upon it. When barium chloride is added to its neutral aqueous solution, only a faint cloudiness is produced, until it is heated, when a slight precipitate forms, but even after standing for weeks and long-continued boiling, only a portion of the selenium precipitates. Addition of excess of ammonia to the solution, however, precipitates a basic barium salt. It is but sparingly soluble in cold alcoholic ammonia. 1:6658 gram of solution from which crystals had deposited, left a residue of 00134 gram, reduced to acid salt, which is equivalent to a solubility 1888.] Compounds of Ammonia with Selenium Diowide. 113 of one part in 116 at 12°. Heated with the alcoholic ammonia it dissolves freely, but on cooling, the solution remains long super- saturated, crystals continuing to deposit for several days. It is very slightly volatile at ordinary temperatures, both in a vacuum and in a current of air. As might be expected, potash at once liberates ammonia from it. Sulphurous acid and stannous chloride reduce it with separation of selenium. It is only slightly affected by hydro- chlorie or nitric acid in the cold, but strong sulphuric acid reacts violently upon it, a portion of the salt being sublimed by the heat evolved. Chlorine passed through its aqueous solution converts it completely into ammonium selenate,—a reaction which was taken advantage of for its analysis. 0°7820 gram was dissolved in water, saturated with chlorine, and barium chloride added. The resulting barium selenate weighed 1°5150 gram, equivalent to a percentage of 76°84 of selenium dioxide. The ammonia was estimated by Kjel- dahl’s process, slightly modified on account of the volatility of the substance. 0°5651 gram was mixed roughly with potassium perman- ganate in a small strong flask by means of a glass rod, after which a thin tube containing 10 c.c. of sulphuric acid mixture was lowered into it, and broken by shaking the flask after it had been well secured with an india-rubber cork. It was then heated to 150° for one hour in a paraffin bath. The contents of the flask distilled with potash yielded 0°13175 gram of ammonia, equivalent to a percentage of 23°32. The results obtained agree with the composition— INH,,SeO, = NH,,Se0,(NH,). Calculated. Found. . Ag,,0,SO,aqg = 20390 « . =O. Whilst the highest observed values in the case of the first three metals fall short of these by 4 to 5 decivolts, and with less active aération plates the deficiency is much greater. Silver, however, when employed as oxidisable metal, does not show this falling off, but rather the reverse, the highest value observed (platinum black) being about 0°58, and the next highest (platinum sponge) about 0°46, both | exceeding the E.M.F. calculated from the heat value; obviously this is due, not to anything connected with the aération plates, but rather to the large negative value of the thermo-voltaic constant} pertaining to silver in contact with sulphuric acid, evidenced also by the circum- stance observed by us, that when silver is substituted for zine in a Grove’s cell, instead of the E.M.F. being depressed by an amount * Taking J = 41°5 x 10*, and the unit C.G.S. current as evolving 0°0001036 gram of hydrogen per second, whence the factor for converting gram-degrees into volts is sensibly 4300 x 10-8 = 0°000043 per gram-equivalent. t ‘Phil. Mag.,’ vol. 19, 1885, pp. 1 and 102. VOL. XLIY. P 196 —-Dr. C. R. A. Wright and Mr. C. Thompson. [May 3, corresponding with the difference in heat of formation of zinc and silver sulphates (85700 gram-degrees = 1:843 volts) it is only depressed by an amount short of this by some 5 or 6 decivolts. Similarly in the ammoniacal cells where (as in the caustic soda cells) the action consists in the oxidation of a metal and the solution of the oxide formed in the ammoniacal liquor, Julius Thomsen gives the ‘heat values— Piers aie tts Zn,O = 85430 = 1°837 volt. Copper iat Cu,,0 = 40810 = 0°877_ ,, DIVER Sales Hehe Ao O ==. 15900 = 'Dabez a Whence the H.M.F. corresponding with the total chemical change must somewhat exceed these amounts by the quantity representing the respective heats of solution in ammonia liquor of the metallic oxides: the highest values observed with zine and copper fall dis- tinctly short of these amounts, whilst the numbers obtained with many kinds of aération plates in weaker solutions exhibit a large deficiency ; on the other hand, cells containing silver as oxidisable metal show no large falling off, and in the ease of the highest values an actual excess of H.M.F., again indicating a somewhat large negative value for the thermo-voltaic constant applicable to silver in contact with ammoniacal fluids. 4 It is noticeable that the values of K, deduced above are not widely different from those equivalent to the difference in heat of oxidation of the various metals, silver excepted: thus with the caustic soda ‘ cells— Zn,O — 85430 ° m Oye £ ie : 3 Pb,O = Sees Difference —35130 = —0°755 volts. Observed values...... from —0°678 to —0°691. With the sulphuric acid cells the differences between the heat of formation of copper sulphate, and that of zinc, cadmium, and silver sulphates respectively, are +50130, +383540, and —35570, corre- sponding with—- Volts. Observed values of Ko. Copper replaced by zinc = +1:078 | +0°:970 to +1:054 Copper replaced by cadmium = +0°721 | +0°720 to +0°725 Copper replaced by silver = —0-765 About —0-020 With the ammoniacal cells the differences between the heat of formation of cuprous oxide and of zinc and silver oxides respectively are +44620, and —34910, corresponding with— eo - 1888.] Development of Electricity by Atmospheric Oxidation. 197 Volts. Observed values of Kg. -Copper replaced by zine = +0:960 | +0°920 to +0°960 Copper replaced by silver = —0°750 | —0°340 to —0°385 Whilst with zinc, lead, copper, and cadmium, the observed values of K, in no case differ very widely from those equivalent to: the differ- ences in heat of formation, those observed with: silver show large differences, indicating as before that silver exhibits a’ high negative™ value for its thermo-voltaic constant in each case, viz., —0°5 to —0°6- in contact with dilute sulphuric acid, and near to —0°4 in contact with ammoniacal fluids, this latter value being close to those found: previously for silver in: contact with neutral solutions of its sulphate, nitrate, and: acetate (loc. cit.): ' On the whole, except when an oxidisable-metal is used exhibiting a high negative value for its thermo-voltaic constant, the E.M-F. of a cell containing an aération plate and am oxidisable metal always falls short, and: sometimes largely short, of that equivalent‘to the chemical changes‘going on therein even under the most favourable conditions: when generating only an infinitesimal current, the de- ficiency being still more marked when the current density is not so minute: in other words, the modus operandi: of cells of this class is such as necessarily to render a*large fraction of the energy non- adjuvant so far as-current is concerned. Just the same remarks apply, as far as our experiments have gone, to cells in which the oxidisable substance is in solution, an extreme case of which is exhibited by cells set up with a solution of sulphurons acid and a sub- merged platinum foil plate, opposed to an aération plate of platinum sponge on the surface of dilute-sulphuric-aeid. Such cells give an E.M.F. (when: generating only extremely small currents) of from 02 to 0°3 volt, whilst the heat of oxidation of sulphurous acid soluticn, SO,aq,0, is 63634. gram-degrees, according to Julius Thomsen,- eorresponding with 1:368 volt, or upwards of a volt more than: that actually produced.* Analogous diminutions in E.M.F. are brought about in many other cases, to: extents depending not only on the _ nature of the aération plate but also on that of the oxidisable fluid. * A large part of the depreciation in this case is due to the fact that sulphurous acid solution and platinum constitute an oxidisable portion of a cell behaving as magnesium and aluminium do in cells where they replace zine, i.e., giving a much smaller E.M.F. than that due to the heat corresponding with the chemical change: thus, if a cell be set up with zine or dilute sulphuric acid opposed to platinum in sulphuric chromic acid solution, and the zine and sulphuric acid be then replaced by platinum and sulphurous acid solution, the E.M.F. falls by an amount greater by 0°45 to 0°5 volt than that corresponding with the differences in heat evolu- tion between Zn,O,SO.aq and SO_aq,0 (viz., 106090 — 63634 = 42456 gram-degrees = 0°913 volt): and similarly with other oxidising fiuids. Solutions of alkaline sulphites behave similarly. P 2 198 Dr. C. R. A, Wright and Mr. C. Thompson. [May 3, Effect of Substituting Oxygen for Arr. In order to see if any material improvement in the H.M.F. of aération cells could be effected by substituting tolerably pure oxygen for atmospheric air, we carried out a number of observations with — plates under a bell-jar supplied with purified oxygen from a reservoir by means of tubes passing through a cork in the narrow mouth. Readings were first taken for a few days with ordinary air in the jar; oxygen was then admitted and passed through till gradually all air was displaced, and after a day or two when the readings had become constant another series of readings for some days was taken. The oxygen was then displaced by air and another series taken, and so on alternately several times. The following average values were ulti- mately obtained showing a small, though decided, increment in H.M.F. when atmospheric air was replaced by oxygen. Increment in E.M.F. in Oxygen. Caustic soda, Sulphuric acid, 7 ‘15Na,0,100H,0. 10H,S80,,100H,0. Platinum sponge ..4....0...006 a3 0°016 , 0-028 Pietra, Foils yas a eweiniam pn ee ee 0-012 0-001 GOld SporiBel hss, «eres aiele tix onaeies . 0°032 Goloitone as Go aldaca ee semen > 0-012 © 002 Palladium sponge.............. 45 0-033 Palladium foil..... homer cet a “0 013 : Silver sponge ...... himeaia oie hee. 0 016 ° SUlver LON ye pete tiene aap we fej cele satiate 0°016 . Gira PlNbe are atta ee eae cee cite ee 0°015 as 0-002 Aération Plates in Contact with Oxidisable Atmospheres. Some analogous experiments were made with aération plates in contact with an oxidisable atmosphere (hydrogen or coal-gas), and an electrolytic fluid united by means of a siphon with an external vessel containing an oxidising solution {alkaline permanganate, sulphuric acid containing chromic acid, nitric acid, &c.) in which a plate of platinum foil was immersed. The readings thus obtained were nothing like as concordant as thase above described (probably from the difficulty of excluding air completely), showing a tendency to rise continually. The following readings were obtained after several days when ‘the rise ‘had either ceased or greatly slackened in most cases ; little difference was observed whether pure hydrogen ¢ or coal-gas was used. A. Cells set up with 7‘15N. 2,0,100H,0 i in contact with the aération plates, opposed to platinum foil immersed in a solution of the same —— : 1888] Development of Electricity by Atmospheric Oxidation. 199 strength shaken up with powdered potassium permanganate to saturation. B. Cells set up with 10H,SO,,100H,O in contact with the aération plates opposed to platinum immersed in the same liquid after agitation with chromic anhydride to saturation. A. Alkaline cells. B. Acid cells. | , Hydrogen. Coal-gas. Hydrogen. Coal-gas. Platinum sponge..... 1°525 1°10 | 1°02 1°10 Platinum foil........ 0 °865 O° 85- 0°89 | 0 895 Silver sponge ........ 0°422 0-425 ‘ Ae Belver tml. .......--. 0°73 0°78 = a Gold sponge......... Ae i 0°845 0°85 SS Baers , | O72. 0°75 0°87 0-90 Palladium sponge .... ala -- 1°37 1°37 Palladtamfou.......| 0°87 0°81 0°89 1°12 Graphite .....-....- 0°845 0°83 0°85 0°85 In making these observations currents were used, the density of which in no case exceeded 0'02 micro-ampére per square centimetre of aération plate surface. Spongy platinum and palladium obviously are far more effective as regards the H.M.F.set up than the other plates used; the chemical action taking place may be regarded as the decomposition of alkaline permanganate into hydrated manganese dioxide, caustic potash, and oxygen (or of chromic anhydride and sulphuric acid into chromium sulphate, water, and oxygen), and the combination of hydrogen with the oxygen thus set free; according to Thomsen’s values, the heat developed would accordingly be per 16 grams oxygen evolved— Alkaline cells. Acid cells. Decomposition of oxidising agent.. 4 x 28355 = 9452 = x 30407 = 10136 Oxidation of hydrogen....... = €8360 68360 | 77812 78496 Corresponding with volts...... = 1673 1688 Hence, even with the most effective plates, the E.M.F. actually - generated falls distinctly short of that corresponding with the heat of chemical change. On making the current passing larger by diminish- ing the external resistance, the E.M.F. always fell rapidly ; so that in order to obtain a current capable of producing any considerable 200 S08 Presents. eS May 8; amount of electrolytic decomposition in a voltameter, it was practi- cally impossible to have an acting E.M.F. as high as 1 volt, even with tolerably large platinum sponge plates. Much the same result was obtained on opposing to one another two platinum sponge aération plates, one in an atmosphere of hydrogen or coal-gas, the other in contact -with air; im no case could any current capable of depositing a few milligrams of silver per day be obtained with an EH.M.F. as great as 1 volt; 1.¢., a total depreciation of upwards of 0°5 volt was occasioned, or more than one-third of the energy due to the chemical change, viz., oxidation of hydrogen to water, representing 68360 gram-degrees, or 1°470 volt. The economical production of currents by the direct oxidation of com- bustible gases, therefore, does not seem at present to be a problem likely to be readily solved. The Society then adjourned over Ascension Day :to Thursday, May 17th. Presents, May 3, 1888. Observations and ‘Reports. Barbados :—Report upon the Rainfall of Barbades, and upon its Influence upon the Sugar Crops. 1847-74. Folio. Barbados 1874. The Meteorological Office, London. Calcutta :—Meteorological Office. Indian Meteorological Memoirs. Vol. IV. Parts 2-3. 4to. Caleutta 1887; Report on the Meteorology of India, 1885. 4to. Calcutta 1887. The Office. Cape Town :—Meteorological Commission. Reports. 1879, 1881-83. Folio. Cape Town 1880-84. The Meteorological Office, London. Parliament of the Cape of Good Hope. Acts, Session 1887. Folio. Cape’Town 1887; Votes and Proceedings, 1887. 4 vols. Folio and 8vo. Cape Town. The Cape Government. Edinburgh :—Scottish Marine Station, Granton. General Account of the Scientific Work of the Station. S8vo. Edinburgh 1885. The Meteorological Office, London. Hamburg :—Denutsche Seewarte. Archiv. Jahrg. Hil. No. 3. Ato. Hamburg 1880. The Meteorological Office, London. - India :—Areheological Survey of India. Report. Vol. XXIII. 8vo. Calcutta 1887; General Index. Vols. I-XXIII. 8vo. Calcutta 1887. : The Survey. Geological Survey of India. Records. Vol. XXI. Part I. 8vo. Calcutta 1888. The Survey. SS | Caney 0 a 201 Observations, &c. (continued). New York:—Geological Survey of the State of New York. Paleontology. Vol. V. Part 1. Vol. VI. 4to. Albany 1885-87. The Survey. - Nice:—Observatoire. Souvenir de la Conférence Géodésique, Session 1887. Obl. 4to. | M. Bischoffsheim. Trieste :—Osservatorio Marittimo. Rapporto Annuale. 1885. Ato. Trieste 1887. The Observatory. _ Upsala:—Expédition Suédoise au Spetsberg, 1882-83. Comptes Rendu. 8yvo. Upsala 1884. The Meteorological Office, London. Berthelot (M.) Collection des anciens Alchimistes Grees. Livr. T. 4to. Paris 1887. Ministére de |’Instruction Publique. Blanford (H. F.), F.R.S. On the Influence of Indian Forests on the Rainfall. 8vo. Calcutta 1887. The Author. Boltzmann (L.) Gustav Robert Kirchhoff: Festrede. 8vo. Leipzig iy. eae. The Author. Cassel (P.) Mischle Sindbad, Secundus—Syntipas. 8vo. Berlin 1888. | The Author. Dawson (G. 8S.) Notes and Observations on the Kwakiool People of Vancouver Island. 4to. Montreal 1888. The Author. Foster (J.) Alumni Oxonienses: the Members of the University of: Oxford, 1715-1886. Vol. I. 8vo. London 1888. nee, | The Anthor. Fourier (J. B. J.) &uvres. Publiées par les soins de M. Gaston. Tome I. 4to. Paris 1888. | M. Darboux. Hennessy (H.), F.R.S. On the Distribution of Temperature over Great Britain and Ireland. 8vo. Dublin 1888. The Author. Hirn (G. A.) Remargues sur un Principe de Physique d’ou part M. Clausius dans sa Nouvelle Théorie des Moteurs 4 Vapeur. Ato. Paris 1888. The Author Jordan (J. B.) The Glycerine Barometer. 8vo. London 1881. - The Author. Kolliker (A.), For. Mem. R.S. Ueber die Entstehung des Pigmentes in den Oberhautgebilden. 8vo. Wiérzburg 1887; Ueber die Entwicklung der Nagel. 8vo. Wiirzburg 1888. The Author. Lissauer (A.) Die Prihistorischen Denkmiler der Provinz West- preussen und der Angrenzenden Gebiete. 4to. Leipzig 1887. ; Naturforschende Gesellschaft zu Danzig. Liversidge (A.), F.R.S. The Minerals of New South Wales, &c. 8vo. London 1888. The Author. Moukhtar Pasha (His Excellency). ‘“‘ The Garden of Moukhtar’”’ [an 202 Prof. J. Burdon Sanderson. On the [May 17, Account of Ancient Oriental Methods in Astronomy and Mathe- matics, in the Turkish Language]. Part 2. Folio. [1887]. H.E. Ghazi Moukhtar Pasha. Plantamour (Ph.) Des Mouvements Périodiques du Sol. (9e Année.) Svo. Genéve 1887. The Author. Schiaparelli (G. V.) Osservazioni Astronomiche e Fisiche del Pianeta Marte (Mem. 3a). 4to. Roma 1886. The Author. Velschow (F. A.) The Natural Law of Relation between Rainfall and Vegetable Life and its application to Australia. 8vo. London 1888. The Author. Wardle (T.) Royal Jubilee Exhibition, Manchester, 1887. Descrip- tive Catalogue of the Silk Section. 8vo. Manchester [1888]. The Author. Weihrauch (K.) Neue Untersuchungen iiber die Bessel’sche Formel und deren Verwendung in der Meteorologie. 8vo. Dorpat 1888. The Author. May 17, 1888. Professor G. G. STOKES, D.C.L., President, in the Chair. The Presents received were laid on the table, and thanks ordered for them. The following Papers were read :— I. “On the Electromotive Properties of the Leaf of Dionea in the Excited and Unexcited State. No. IL” By J. Burpon SANDERSON, M.A., M.D., F.R.S., Professor of Physiology im the University of Oxford. Received April 17, 1888. (Abstract.) The author has continued his experimental enquiries, of which the results were communicated to the Royal Society under the same title in 1881. In the introduction to the paper he gives a summary of his previous observations, which led to the conclusion that the property, by virtue of which the excitable structures of the leaf respond to stimulation, is of the same nature with that possessed by the similarly- endowed structures of animals. He them proceeds to state that the main purpose of his subsequent investigations has been to determine the relation between two sets of phenomena which might, in accord- ance with the language commonly used in animal physiology, be termed respectively those of the “resting current” and of the “action 1888.] LElectromotive Properties of the Leaf of Dionza. 203 current ” of the leaf, 7.e., between the electrical properties possessed by the leaf when stimulated, and those which it displays when at rest. Assuming the excitatory response in the leaf to be of the same nature as the excitatory variation or “action current” in muscle and nerve, the question has to be answered, whether in the leaf the response is a sudden diminution of a previously existing electromotive action (according to the pre-existence theory of du Bois-Reymond), or the setting up at the moment of stimulation of a new electromotive action—in short, whether and in how far the two sets of phenomena are interdependent or the contrary. An observation recorded in his former paper suggested proper metheds. It had been shown that by passing a weak voltaic current through the leaf for a short period in a particular direction, its electromotive properties could be permanently modified without loss of its excitability. If it could be shown that the influence of this modification extended to both orders of phenomena, those of rest and of excitation, and that both underwent corresponding changes of character under similar conditions, this would go far to prove that an essential relation existed between them. Acting on this suggestion, the author has had recourse to modes of experiment similar to those which have been employed during the last few years in the investigation of the newly-diseovered “secondary electromotive” phenomena of muscle and nerve (see ‘Oxford Biological Memoirs,’ vol. 1, part 2). The details of these experiments, made in 18835, are given in the first three sections of the paper. They relate to (1) the more immediate effect of the current as seen in the records of successive galvanometric observations made at regular intervals ; (2) the more permanent influence of the current on the electromotive properties of the unexcited leaf, and on its electrical resistance; and (3) the concomitant modification of its behaviour when stimulated. The general result of these experiments is to show that the two orders of phenomena, the excitatory and those which relate to the resting state, are so linked together that every change in the state of the leaf when at rest conditionates a corresponding change in the way in which it reacts to stimulation—the correspondence consist- ing in this, that the direction of the response is opposed to that of the previous difference of potential between the opposite surfaces, so that as the latter changes from ascending to descending, the former changes from descending to ascending. _ The author considers that this can only be understood to mean that the constantly operative electromotive forces which find their expression in the persistent difference of potential between the opposite surfaces, and those more transitory ones which are called into momentary existence by touching the sensitive filaments or by 204 Magnetic Qualities of Nickel. = [May 11, other modes of stimulation, have the same seat, and that the opposi- tion between them is in accordance with a principle applicable in common to the excitable structures of plants and animals, viz., that the property which renders a structure capable of undergoing excitatory change is expressed by relatwe positivity, the condition of discharge by relative negatwity. . With reference to the mode of action of the voltaic current, the effect produced in the unexcited leaf is compared with that observed in the unexcited. electric organ of the skate or the torpedo, in both of which, as in the leaf, it is observed that, although the after-effect of a current led across the disks or plates is to increase the difference of potential between its two surfaces, whichever way the current is’ directed, the effect is much greater when the direction of the external current coincides with that of the normal electromotive action of the organ than in the opposite case. It is further shown that the electromotive changes concerned in ‘‘ modification ” and “‘ excitation” have their seat at the upper surface of the lamina. If, as the author believes, all these changes depend on difference of physiological activity between adjacent excitable cells or strata of cells of which the protoplasmic linings are in continuity, it must be supposed that when the leaf is at its prime, the most super-- ficial strata are positive to those subjacent, and that as the former lose their pristine susceptibility of excitatory change, the physio- logical, and consequently the electrical, difference between them is diminished, annulled, or reversed. The fourth section of the paper is devoted to an investigation made: in 1887, of the events of the first second after excitation made with the aid of a pendulum-rheotome specially adapted for the purpose. The fifth contains the description of the records obtained by photo- graphing the electric phenomena of the excitatory reaction, as ob- served with the aid of the capillary electrometer, on rapidly moving plates. Both of these series of observations serve to confirm and complete the results obtained by other methods. II. “Magnetic Qualities of Nickel.” By J. A. Ewrne, F.R.S., Professor of Engineering, University College, Dundee, and G. C. Cowan. Received April 26, 1888. (Abstract. ) The experiments described in the paper were made with the view of extending to nickel the same lines of enquiry as had been pursued by one of the authors in regard to iron (‘ Phil. Trans.,’ 1885, p. 523). Cyclic processes of magnetisation were studied, in which a magnetising. 1888.] On the Sources of the Nitrogen of Vegetation. 205 force of about 100 c.g.s. units was applied, removed, reversed, again removed, and re-applied, for the purpose of determining the form of the magnetisation curve, the magnetic susceptibility, the ratio of residual to induced magnetism, and the energy dissipated in conse- quence of hysteresis in the relation of magnetic induction to magnet- ising force. Curves are given, to show the character of such cycles for nickel wire in three conditions: the original hard-drawn state, annealed, and hardened by stretching after being annealed. The effects of these have also been examined (1) by loading and unloading magnet- ised nickel wire with weights which produced cyclic variations of longitudinal pull, and (2) by magnetising while the wire was sub- jected to a steady pull of greater or less amount. The results confirm and extend Sir William Thomson’s observation that longi- tudinal pull diminishes magnetism in nickel. This diminution is surprisingly great: it occurs with respect to the induced magnetism under both large and small magnetic forces, and also with respect to residual magnetism. The effects of stress are much less complex than in iron, and cyclic variations of stress are attended by much less hysteresis. Curves are given to.show the induced and residual mag- netism produced by various magnetic forces when the metal was Maintained in one or other of certain assigned states of stress; also the variations of induced and residual magnetism which were caused. by loading and unloading without alteration of the magnetic field. Values of the initial magnetic susceptibility, for very feeble magnet- ising forces, are stated, and are compared with the values determined by Lord Rayleigh for iron, and the relation of the initial susceptibility to the stress present is investigated. The paper consists mainly of: diagrams in which the results are graphically exhibited by means of. curves. iL “ On the present Position of the Question of the ‘Sources of the Nitrogen of V.egetation, with some new Results, and preliminary Notice of new Lines of Investigation.” By Sir J.B. LAwEs, F.R.S., and J. H. GiuBert, M.A., LL.D., F.R.S., Sibthorpian Professor of Rural Economy in the University of Oxford. Received, Part I, July 20, 1887. Parts II and III, May 3, 1888. |For Preliminary Notice of this Paper, see vol. 48, p. 108.] 206 Prof. J. A. McWilliam. [May 17, IV. “On the Rhythm of the Mammalian Heart.” By J. A. McWrutiay, M.D., Professor of the Institutes of Medicine in the University of Aberdeen. Communicated by Pro- fessor M. Fostmer, Sec. R.S. Received April 26, 1888. The following are some of the general conclusions arrived at from a prolonged investigation of the rhythm of the mammalian heart. The experiments were conducted on the cat, dog, rabbit, rat, hedgehog, and guinea-pig, the cat being the animal most commonly used. The animals were anesthetized, artificial respiration was kept up, the thorax was laid open, and the action of the heart was recorded by various adaptations of the graphic method :— 1. Minimal stimulation of the quiescent cardiac muscle is at the same time maximal ; a stimulus which is strong enough to excite con- traction at all excites a maximal contraction. The strength of an artificially excited beat does not depend on the strength of the stimulus; it is equally strong with maximal and minimal excitation. I have ed this point in various ways =— (1.) On the excised heart which has ceased contracting spon- taneously, but is still quite capable of being artificially excited to beat. (2.) On the intact heart reduced to a state of quiescence by vagus stimulation. (3.) On intact hearts which beat slowly in consequence of cooling and other circumstances ; the stimulations were applied during the quiescent period intervening between two spontaneous contractions. 2. The condition of fibrillar contraction or heart-delirium induced in the ventricles of excitable hearts by the application of interrupted currents and other means can be recovered from even after long periods (three-quarters of an hour, &c.) under the combined influence of artificial respiration, rhythmical compression of the ventricles, and. the administration of pilocarpin. When the excitability of the cardiae musele has been much depressed (by pilocarpin, certain phases of exhaustion, &c.), the application of interrupted currents does not induce fibrillar contraction, but merely a series of rhythmic beats in the case of a quiescent organ, or an accelera- tion of the rhythm already present in a heart which is beating spon- taneously. 3. The spontaneous rhythmic power possessed by the terminal parts of the great veins, the auricles, and the ventricles, seems, 1m some con- ditions at least, to be myogenic. 4. In the intact heart the auricles and ventricles do not beat in virtue of their own independent rhythmic power, but in obedience to 1888.] On the Rhythm of the Mammalian Heart. 207 impulses reaching them from the terminal or “ostial” parts of the ereat veins. For though both auricles and ventricles possess an inherent rhythmic tendency, the ostial parts of the great veins possess a higher power of spontaneous rhythm, and hence dominate the rhythm of the whole heart. The rapidly recurring contractions arising in the ostial regions are propagated over the whole organ; the more rapid rhythm of the ostial parts supersedes and renders latent the less rapid inherent rhythm of the auricles and ventricles. In support of this view there can be adduced many facts, Among others— (1.) The independent rhythm of the auricles and ventricles appears to be decidedly slower than that of the terminal or ostial parts of the veins. (2.) Slight heating of the ostial part of a great vein (e.g., the termination of the vena cava supericr) causes a marked acceleration in the rhythm of the whole heart, while a similar heating of the ventricular wall causes very little change, or | ame commonly) none at all. Weak faradic and galvanic currents induce similar results in this respect. | _ (38.) In the dying heart the power ef spontaneous rhythmic con- traction survives longest in the ostial parts of the veins. This is analogous to what obtains in the hearts of cold-blooded animals, where the greatest vitality 1s exhibited by the sinus venosus, the part pos- sessed of the highest spontaneous rhythm, 7.¢., the leading or dominant _ part of the organ. 5. The normal sequence of the ventricular contraction upon the auricular contraction in the intact heart is essentially determined by nervous influences. It is not dependent on— (1.) The distension of the ventricles with blood pumped in from the auricles. (2.) The mechanical relations normally obtaining between the auricles and ventricles through the medium of the auriculo-ventricular valves and the chorde tendinee ; or (3.) The occurrence of an electrical change (current of action) in the auricular muscle as one of the phenomena of its contraction. 6. The nervous influence determining the ventricular sequence is probably of an intermittent character. 7. The propagation of the contraction within the walls of the auricles and ventricles is not dependent on the action of the nerves _ lying near the surface of these parts. The contraction continues to be propagated quite well when the surface (e.g., of the ventricles) has been washed with strong ammonia. 8. In the auricles at least, the ordinary beat is not the result of a 208 | Prof. J. A. McWilliam, [May 17, ‘simultaneous motor discharge from a nerve centre to all the muscular fibres; the contraction is, on the other hand, a progressive process passing over the auricular walls in a wave-like fashion, 9. A reversal of the normal sequence of the heart’s contraction can be induced and kept up for a considerable time by applying to the | ventricles a series of single stimulations (e.g., induction shocks) at a rate somewhat more rapid than that of the spontaneous rhythm of the organ. V. “Inhibition of the Mammalian Heart.” By JOHN A. McWitiAm, M.D., Professor of the Institutes of Medicine in the University of Aberdeen. Communicated by Pro- fessor. M. Foster, Sec. R.S. Received May 3, 1888. The following conclusions are based upon a long series of experi- ments performed upon the cat, dog, rabbit, rat, fedehios. and guinea- pig, the cat being the animal commonly used. The animals were Guilecthotueds usually with chloroform ; artificial respiration was kept up; the thorax and often the pericardial sac were laid open, and the action of the heart was examined with the aid of the graphic method. Section of the Vagi. The results of section of both vagi vary according to the conditions obtaining at the time the nerves: are cut—according to the amount of controlling influence exercised by the medullary cardio-inhibitory centre upon the heart. When the cardio-inhibitory centre is inactive, section of the vagi causes no appreciable change in the heart’s action. On the other hand, section of the nerves at a time when the con- trolling influence of the medullary centre is acting to a decided extent, is followed by very pronounced results—by an increase not only in the rate of the cardiac beat, but also in the contraction force of both the auricles and the ventricles. There is a marked augmentation in the strength of the beats; the change in the energy of the auricular contractions is usually more extensive than that occurring in the case of the ventricles. Stimulation of the Vagus Nerve. The latent period of vagus stimulation varies remarkably in different conditions ; there is often a period of many seconds before the heart stands still. When the vagus nerve is stimulated so as to slow the heart, it is usually seen that the inhibitory influence is not of maximal intensity at its first manifestation, but goes on increasing for some time. 1888.] — Inhibition of the Mammalian Heart. 209 Effects of Vagus Stimulation on the Auricles. 1. The vagus appears as a rule to influence the auricles more readily and more powerfully than the ventricles. 2. Vagus stimulation leads to a slowing or an arrest of the rhythmic beat, and a very marked weakening of the contraction force. The recommencing auricular beats that occur when the period of inhibition is passing away are very weak;: and any contractions excited by direct stimulation (e.g., with fed shocks) during the period of standstill are strikingly enfeebled. 3. Vagus stimulation causes a pronounced depression of the excita- bility of the auricular tissue to direct stimulation. During the period of inhibition resulting from vagus stimulation it is much more difficult than usual to excite an auricular beat by direct excitation; a much stronger stimulus is necessary to elicit any con- traction at all. 4, The tone of the auricular muscle appears to be markedly dimi- nished. 5. These results occur when the vagus is stimulated, even when the superior and inferior. vene cave: have been clamped, so that the _ cavities of the heart are no longer filled with blood. 6. The vagus nerve seems to exert a powerful influence of a more or less direct nature on the muscle itself, not merely by inhibiting or weakening the motor impulses which are commonly assumed to pass from nerve centres in the heart to the muscular fibres.. For if it were true that the vagus acted simply by depressing the motor centres of the heart, it is very difficult to conceive how the responsiveness of the auricular muscle to direct. stimuli should be so greatly diminished, and how the contraction force should be so strikingly reduced when the auricular muscle is made to contract by induction shocks applied to the auricular tissue. ) It would seem that whatever changes the vagus may induce in the nerye-cells and ganglia occurring plentifully in the auricles, it can also exert an important influence on the: contractile tissue itself. 7. Upon the whole, the influence of the vagus nerve upon the mam- malian auricles presents a close parallelism to what holds good in the auricles of many cold-blooded animals. Effects of Vagus Stimulation on the Ventricles. Besides causing slowness or standstill, the vagus can cause other important changes in the ventricular part of the heart. 1. The contraction force is markedly diminished. When a period of standstill has ended, the recommencing beats are usually weak; and beats excited by direct stimulation (e.g., single induction shocks) duriny the period of standstill are of diminished size. 210 Prof. J. A. McWilliam, [May 17, When vagus stimulation does not cause complete standstill, but only a marked slowing, the strength of the slow ventricular beats is usually much less than the normal. The reduction in contraction force does not bear any constant rela- tion to the degree of slowing. While all the slow beats are weakened in some degree, a beat occurring after a long pause is sometimes decidedly stronger than one occurring after a shorter pause; on the other hand, the converse more often holds good—a beat oceurring after a long pause is weaker than a beat occurring after a shorter pause. The depression of contraction force does not appear to depend on over-distension of the ventricles during the slowing or standstill; nor upon the fall of arterial pressure that occurs and involves a dimi- nished resistance tu the ventricular systole and a change in the coro- nary circulation. The foree-depressing effects of vagus stimulation can still be seen (1) when the superior and inferior venee cave have been clamped; or (2) when the pulmonary artery or (3) the aorta has been clamped; or (4) when all these vessels have been clamped before the vagus stimu- lation. 2. When slowing or arrest of the ventricular action occurs as a result of vagus stimulation, there is a marked change in the shape and duration of the ventricular curves; the degree of change stands in close relation to the length of the pause preceding each beat. The curves become broader near the top, and their duration is increased. The longer the interval preceding a curve the broader the curve is, and the more markedly is it prolonged. These features are not abolished when the superior and inferior vene cavee have been clamped before the vagus stimulation; nor when the aorta or the pulmonary artery, or all these vessels, have been clamped. 3. The vagus appears to inhibit the spontaneous rhythmic tendency inherent in the ventricles; the ventricular standstill does not appear to be due simply to the standstill of the rest of the heart. 4, At the same time the absence of auricular beats of any consider- able strength is wsually a necessary condition for the occurrence of a protracted ventricular standstill. It commonly but not invariably happens that if the auricles are artificially excited to contract during the period of cardiac standstill, the ventricles beat also in sequence to the artificially excited auricular contraction. 5. When the heart begins to beat after a period of inhibition, the order of contraction most commonly seen is that which obtains normally—ostial parts of the great veins; auricles; ventricles. But sometimes the ventricles recommence, and give one or more beats before any contraction occurs in the other parts of the heart. 6. There are sometimes seen evidences of the occurrence under vagus influence of a block in the propagation of the contraction from, 1888.] Inhibition of the Mammalian Heart. 211 auricles to ventricles. At certain phases of vagus stimulation the ventricles often fail to respond to auricular beats, while at the same time there is evidence to show that this is due not to a depression of the ventricular excitability, but to a break in the transmission of the contraction from the auricles. 7. The maximum intensity of the inhibitory influence exerted by vagus stimulation often obtains at the same time in the auricles and the ventricles. But frequently the auricles become greatly depressed, while the ventricular beats are of undiminished size, or are only beginning to be affected; in rare cases the ventricular contraction force becomes reduced more suddenly than the auricular. 8. The effects of vagus stimulation on the ventricles may be in some measure counteracted by the application to the ventricular surface of a series of stimulations (e.g., single induction shocks) at about the normal rate of the heart’s action. An artificially excited series of beats is thus caused ; these beats give curves of approximately normal form and duration, and they are much stronger than any slowly occur- ring spontaneous beats that appear after the. standstill has lasted for some time; they are also much stronger than single beats excited (by induction shocks) at long intervals during the standstill. The beats of the artificially excited series (at normal rate) are still decidedly weaker than normal beats. On the Existence of a Local “‘ Inhibitory Area” in the Heart. By stimulation of a certain locality on the dorsal aspect of the - auricular surface, certain striking effects are obtained. In the catand dog the area in question is elongated in shape, and is situated over the inter-auricular septum, its long axis running parallel with the plane of the septum. It extends downwards to within a short distance of the coronary sinus. At the right side of the area lies the termina- tion of the vena cava inferior. Many nerves course downwards through this region ; there are also numerous nerve-cells and ganglia. These, however, are not confined to the area in question, but occur in considerable number over the dorsal aspect of the left ventricle, especially in its septal half. The nerves appear to be derived to a considerable extent from the left vagus. The majority of the fibres are non-medullated, but medullated fibres are also present (cat). Ganglia occur in special abundance near the auriculo-ventricular groove. Stimulation of this area with an interrupted current gives results that stand out in sharp contrast to those obtained by stimulating other parts of the auricular wall, e.g., the appendix. Stimulation of the latter causes an acceleration of both auricles and ventricles. The auricles contract with great rapidity, so that they present a peculiar VOL. XLIV. Q 212 Prof. J. A. McWilliam. [May 17, flutterme appearance; the ventricles beat much more rapidly than before, though they do not keep pace with the auricles. On the other hand, stimulation of the inhibitory area, while it causes a rapid fluttering action of the auricles, induces either a very marked slowing, or a complete standstill in the veniricles. This result is a mixed one—ventricular inhibition, resulting from stimula- tion of certain structures in the inhibitory area, and auricular accelera- tion, in all probability due to an escape of the stimulating current to the excitable auricular tissue. The inhibitory effects on the ventricle much resemble those caused by vagus stimulation. There is depression of the ventricular contraction force, and changes in the shape and duration of the ven- tricular curves similar to those occurring under vagus influence. Stimulation of the inhibitory area and of the vagus are both rendered ineffective by the administration of atropine. But there are certain points of difference :-— (1.) The strength of current necessary to inhibit the ventricles is very much less when the current is applied to the inhibitory area than when it is applied to the vagus. (2.) Stimulation of the inhibitory area remains effective in arrest- ing the ventricular action, after curare has been administered in such amount as to cause stimulation of one or both vagi in the neck to be entirely without inhibitory result. (3.) In many instances when the vagi have become exhausted, or have lost their inhibitory power from less definite causes, the inhibitory area remains effective. Tt seems clear from the very different relation borne by the inhibi- tory area to certain poisons, to the strength of stimulating current necessary, to exhaustion, &c., that in exciting this area we are dealing with structures of a more or less special nature, differing markedly in their character from the ordinary inhibitory fibres running in the trunks of the vagus nerves. The important structures of the inhibitory area are situated super- ficially ; they may be readily paralysed by the application of a few drops of a 4 per cent. solution of cocaine hydrochlorate, or of strong ammonia. The region in question does not contain a motor centre for the heart muscle. Destruction of this area does not arrest the spontaneous rhythm of the organ (which indeed originates in parts some distance removed from the inhibitory area, viz., in the ostial parts of the great veins, especially the vena cava superior and the pulmonary veins). Nor is the propagation of the contraction from one part of the heart to another in any way deranged or interfered with. The inhibitory area probably contains structures to which many at 1888.] On the Electric Organ of Raia circularis. 213 least of the inhibitory fibres of the vagus go, there to come into intimate relation with the cardiac mechanism. Lffect of Stimulation of Ostial Parts of Great Veins in certain Abnormal ; Conditions. _At certain stages of the process of asphyxia, and in the dying heart, there is often seen a very remarkable alteration in the behaviour of the ostial parts of the great veins towards direct stimulation with interrupted currents. In such circumstances, an inhibition of the spontaneous rhythmic action of these parts may often be seen as a result of direct stimulation, whereas in the normal state such a stimu- lation is productive of immediate and striking acceleration. VI. “On the Structure of the Electric Organ of Raia circularis.” By J. C. Ewart, M.D., Regius Professor of Natural History, University of Edinburgh. Communicated by Professor J. BuURDON SANDERSON, F.R.S. Received April 30, 1888. (Abstract. ) This paper gives an account of the structure of the cup-shaped bodies, which, as mentioned in a previous paper read 26th April, 1888, make up the electric organs of certain members of the skate family. The structure of these electric cups has been already studied in three species of skate, viz.: Raia fullonia, R. radiata, and £&. circularis. The present paper only deals with the electric organ of BR. circularis. It shows that the cups in this species are large, well-defined bodies, each resembling somewhat the cup of the familiar “cup and ball.” The cup proper, like the disks of fh. batis, consists of three distinct layers, (1) the lining, which is almost identical with the electric plate of R. batis; (2) a thick median striated layer ; and (3) an outer or cortical layer. The lining or electric plate is inseparably connected with the terminal branches of the numerous nerve-fibres, which, entering by the wide mouth in front, all but fill the entire cavity of the cup, and ramify over its inner surface, the intervening spaces being occupied by gelatinous tissue. This electric layer, which is richly nucleated, presents nearly as large a surface for the terminations of the electric nerves as the electric plate which covers the disk in R. batis and R. clavata. The striated layer, as in BR. batis, consists of numerous lamelle, which have an extremely contorted appearance, but it differs from the cor- responding layer in A. batis, in retaining a few corpuscles. The cortical layer very decidedly differs in appearance from the alveolar layer in KR. batis. It is of considerable thickness, contains large nuclei, Q 2 214 Mr. C. Chree. [May 17, and sometimes has short blunt processes projecting from its outer surface. These short processes apparently correspond to the long complex projections which in f&. batis give rise to an irregular net- work, and they seem to indicate that the cortical layer of R. cireularis essentially agrees with the alveolar layer of A. batis, differing chiefly in the amount of complexity. Surrounding the cortex there is a thin layer of gelatinous tissue in which capillaries ramify. This tissue evidently represents the thick gelatinous cushion which lies behind the disk in R. batis, and fills up the alveoli. The stem of the cup is usually, if not always, longer than the diameter of the cup. It consists of a core of altered muscular sub- stance, which is surrounded by a thick layer of nucleated protoplasm continuous with the cortical layer of the cup, and apparently also identical with it. The cups are arranged in oblique rows to form a long, slighily- flattened spindle, which occupies tke posterior two-thirds of the tail, — being in a skate measuring 27 inches from tip to tip, slightly over 8 inches in length, and nearly a quarter of an inch in width at the widest central portion, but only about 2 lines in thickness. The posterior three-fifths of the organ lies immediately beneath the skin, and has in contact with its outer surface the nerve of the lateral line. The anterior two-fifths is surrounded by fibres of the outer caudal muscles. It is pointed out that while the organ in R. circularis is larger than in R. radiata, it is relatively very much smaller than the organ of R. baits. VIL. « On Aolotropic Elastic Solids.” By C. Cares, M.A., Fellow of King’s College, Cambridge. Communicated by Professor J. J. THomson, F.R.S. Received May 1, 1888. (Abstract. ) This paper treats of elastic solids of various non-isotropic kinds. Its object is to obtain solutions of the internal equations in ascending integral powers of the variables, and apply them to problems of a practical kind, some of them already solved, but in an entirely different way, by Saint-Venant. ; On the multi-constant theory of elasticity the equations connecting the strains and stresses contain 21 constants. As shown by Saint- Venant these reduce for one-plane symmetry to 13, for three-plane symmetry to 9, and for symmetry round an axis perpendicular to a plane of symmetry to 5. : Part I of this paper deals with one-plane symmetry. A solution is obtained of the internal equations of equilibrium complete so far as _- his \ pilin hod t = on + 1888. | On Aolotropic Elastie Solids. 215 it goes. It is employed in solving the problem, already treated by Saint-Venant, of a beam, whose length is perpendicular to the plane of symmetry, held at one end, and at the other acted on by a system of forces, whose resultant consists of a single force along the axis of the beam, and of a couple about any line in the terminal section through its centroid. The cross-section may be any whatever, including the case of a hollow beam, provided it be uniform through- out. The case when the cross-section is elliptical, and the beam exposed to equilibrating torsional couples over its ends is also treated. Results are obtained confirmatory of Saint-Venant’s. They are also extended to the case of a composite cylinder, formed of shells of different materials whose cross-sections are bounded by concentric similar and similarly situated ellipses, the law of variation being the same for all the elastic constants of the solution. The limiting case of a continuously varying structure is deduced. Ié is found when a beam is exposed to terminal traction, whether uniform or not, that the strain consists in part of a shear in the plane of the cross-section which is proportional to the traction; and the position of the lines in the cross-section, which being originally at right angles remain so, is determined. These lines are called principal - axes of traction. If there are in addition two planes of symmetry through the axis of the beam, these principal axes are the intersec- tions of the planes of symmetry with the cross-section. _ When a beam of circular section is exposed to torsion, it is proved that warping will ensue proportional to the moment of the twisting couple. Only two diameters in the cross-section, and these mutually at right angles, remain perpendicular to the axis of the beam. These are called principal axes of torsion. If w denote displacement parallel to the axis of the beam, andr, @ denote the undisturbed polar co-ordi- nates of a point in the cross-section, referred to its centre as origin, and one of these axes as initial line, the law of warping is given by— we r? sin 2¢. There is in general no connexion between the positions of the prin- cipal axes of traction and of torsion, as the expressions giving their inclination to the axes of co-ordinates contain wholly different elastic constants; but for three-plane symmetry of the kind already men- tioned they coincide. When the material is symmetrical round the axis of the beam, the shear and the warping of course are found to vanish. It is pointed out how by means of these various properties _ the nature of the material may be investigated experimentally. Part II treats of a material symmetrical round an axis, that of z, and having the perpendicular plane one of symmetry. A general solution of the ‘internal equations of equilibrium is obtained, sup- 216 Mr. C. Chree. [May 17, posing no bodily forces to act. The solution involves arbitrary con- stants, and consists of a series of parts, each composed of a series of terms involving homogeneous products of the variables, such as a! ym gn—l—m, where 1, m, n are integers, and ” is greater than 3. The case 1 = 7 is worked out numerically as an illustration. *The terms involving powers of the variables, the sum of whose indices is less than 4, are then obtained by a more elementary process, and these alone are required in the applications which follow. These terms arrange themselves in groups associated with certain constants in the expression found for the dilatation. The first application of the solution is to “ Saint-Venant’s problem ” for a beam of elliptical cross-section. The problem is worked out without introducing any assumptions, and a solution obtained, which is thus directly proved to be the only solution possible if powers of the variables above the third be neglected. Certain groups of associated constants vanish completely, and the remaining arbitrary constants express themselves very simply in terms of the terminal forces, all the constants of one group depending on one only of the components of the system of forces. Part III consists of an application of the second portion of the solution of Part II to the case of a spheroid, oblate or prolate, and of any eccentricity, rotating with uniform angular velocity round its axis of symmetry, oz, which is also the axis of symmetry of the material. The surface of the spheroid is supposed free of all forces. The terms depending on two only of the groups of associated con- stants suffice, along with a particular solution on account of the _ existence of what is equivalent to the occurrence of bodily forces, to satisfy all the conditions of the problem, and the strains are deter- mined explicitly. The limiting form of the solution when the polar axis of the spheroid is supposed to diminish indefinitely, while the equatorial remains unchanged, is applied to the case of a thin circular disk rotating freely about a perpendicular to its plane through its centre. The solution so obtained is shown to satisfy all the conditions required for the circular disk, except that it brings in small tangential surface stresses depending on terms of the order of the thickness of the disk. According to this solution the disk increases in radius, and diminishes everywhere in thickness, especially near the axis, so as to become biconcave. All, originally plane, sections parallel to the faces become very approximately paraboloids of revolution, the latus rectum of each varying inversely as the square of the angular velocity into the original distance of the section considered from the central section. Again, by supposing the ratio of the polar to the equatorial diameter of the spheroid to become very great, a surface is obtained which near the central plane, z = 0, of the spheroid differs very little q . 1888.] On Holotropic Elastic Solids. 217 from that of a right circular cylinder. The corresponding form of the solution obtained for the spheroid, when the ratio of the polar to the equatorial diameter becomes infinite, may thus be expected to apply very approximately to the portions of a rotating cylinder not too near the ends, and thus for a long thin cylinder to be for all practical purposes satisfactory. This is verified directly, and it is shown that this solution is in all respects as approximately true as that universally accepted for Saint-Venant’s problem. According to the solution the cylinder shortens, and every cross-section increases in radius but remains plane. The shortening and the increase in the radius are, of course, proportional to the square of the angular velocity. Part IV treats of the longitudinal vibrations of a bar of uniform circular section and of material the same asin Part II. Assuming strains of the form— radial = r y(r) cos(pz—«) cos kt, longitudinal = ¢(1r) sin(pz—z«) cos Kt, #(r) is found in terms of ¥-(r) by means of the equations established in Part Il. From these equations is deduced a differential equation of the fourth order for y(), and for this a solution is obtained con- taining only positive integral even powers of vr. A relation exists determining all the constants of the solution in terms of the co- efficients a) and a, of r9 and r*. In applying this solution to the problem mentioned, terms containing powers of 7 above the fourth are neglected, and it is shown to what extent the results obtained are approximate. On the curved surface the two conditions that the normal and tangential stresses must vanish determine a, in terms of dp, and lead to the following relation between & and p— 3 b=. p ya — ipa?o?}, Here p denotes the density and a the radius of the beam, while M is Young’s modulus, and o the ratio of lateral contraction to longi- tudinal expansion for terminal traction. This agrees with a result obtained by Lord Rayleigh* on a special hypothesis. Proceeding to the terminal conditions, it is shown how » is deter- mined from the conditions as to the longitudinal motion at the ends being either quite free or entirely non-existent. Since a, depends only on the amplitude of the vibrations, we are left with no arbitrary constant undetermined. If the bar beso “fixed” at its ends, that the radial motion is unobstructed, this leads to no difficulty, but if an * © Theory of Sound,’ vol. 1, § 157. 218 Presents. [May 17, end be “free” a difficulty arises. At such an end the solution requires the existence of a radial stress U « (27 + 1)? r (a — 7°)/P, where 7 is an integer depending on the number of the harmonic of the fundamental note and / denotes the length of the bar. The value given above for k thus answers to a problem differing to a certain extent from that occurring in nature in the case either of ‘“‘ fixed- free’’ or of ‘‘ free-free”’ vibrations. There will thus be a difference in these cases between the results of experiment and those of the accepted theory, even as amended by Lord Rayleigh. This divergence will increase rapidly with the order of the harmonic, and though very small for a long thin bar will increase rapidly as the ratio of the diameter to the length is increased. Since in dealing with the condi- tions at the curved surface, terms of the order (a/l)® were neglected, the same remarks apply, though to a smaller extent, in the case of the “‘fixed-fixed ” vibrations. From the values of w and w, which are obtained explicitly, it is shown that the hypothesis made by Lord Rayleigh is true as a first, and only as a first, approximation. The Society adjourned over the Whitsuntide Recess to Thursday, May 31st. Presents, May 17, 1888. Transactions. Alnwick :—Berwickshire Naturalists’ Club. History. Vol. XI. Nos. 3-4. 8vo. Alnwick 1887. The Club. Batavia :—Bataviaasch Genootschap van Kunsten en Wetenschap- pen. Dagh-Register gehouden int Casteel Batavia. Anno 1653, Svo. Batavia 1888; Notulen. Deel XXV. Afley. 4. 8vo. Batavia 1888. The Society. Berlin :—Konigl. Preuss. Akademie der Wissenschaften. Politische Correspondenz Friedrich’s des Grossen. Bd. XV. 4to. Berlin 1887. The Academy. Bombay :—Royal Asiatic Society (Bombay Branch). Journal. Vol. XVII. No. 46. 8vo. Bombay 1887. The Society. Brussels :—Musée Royal d’Histoire Naturelle de Belgique. Bulle- tin. Tome V. No.1. 8vo. Bruszelles [1888]. The Museum. Cambridge, Mass.:—Harvard College. Museum of Comparative Zoology. Bulletin. Vol. XIII. No. 8. Vol. XVI. No. 1. 8yo. Cambridge, Mass. 1888. The Museum. Cordova :—Academia Nacional de Ciencias. SBoletin. Tomo X. Entrega 1. 8vo. Buenos Aires 1887. The Academy. Gottingen :—Konigl. Gesellschaft der Wissenschaften. Abhand- lungen. Bd. XXXIV. 4to. Gottengen 1887; Nachrichten. Jahrg. 1887. 8vo. Gottingen. The Society. : 1888.] Presents. 219 Transactions (continued). Leipzig :—Konigl. Sachs. Gesellschaft der Wissenschaften. Abhand- lungen (Philol.-Histor. Classe). Bd. X. No.8. 8vo. Leipzig 1888. ; The Society. London :—College of State Medicine. Calendar. 1888. 8yvo. Lon- don. | The College. Entomological Society. Transactions. 1888. Part 1. 8vo. London. The Society. Institution of Mechanical Engineers. Proceedings. 1888. No. 1. 8vo. London. The Institution. Royal Asiatic Society. Journal. Vol. XX. Part 2. 8vo. London 1888. The Society. Royal Institute of British Architects. Journal of Proceedings. Vol. IV. No. 13. 4to. London 1888. The Institute. Royal Statistical Society. List of Fellows, Rules, &c. 1888. 8vo. London. The Society. Society of Biblical Archeology. Proceedings. Vol. X. Parts 5-6. 8vo. London 1888. The Society. New York :—Academy of Sciences. Transactions. Vol. VI. 8vo. New York [1888]. The Academy. Palermo :—Circolo Matematico. Rendiconti. Tomo I. Tomo II. Fasc. 1-2. 8vo. Palermo 1887-8. The Circolo. Paris :—Société d’Encouragement pour Jl Industrie Nationale. Annuaire. 1888. 12mo. Paris. | The Society. Penzance :—Royal Geological Society of Cornwall. Transactions. Vol. XI. Part 2. 8vo. Penzance [1888]. The Society. Pisa :—Societa Toscana di Scienze Naturali. Processi Verbal. Vol. VI. 8vo. [Pisa] 1888. , The Society. Journals. Astronomische Nachrichten. Bd. CXVIII. 4to. Kiel 1888. The Editor. Bullettino di Bibliografia e di Storia della Scienze Matematiche e Fisiche. Maggio, 1887. 4to. Roma. The Prince Boncompagni. Horological Journal (The) Vol. XXX. Nos. 355-56. 8vo. London 1888. The British Horological Institute. Journal of Comparative Medicine and Surgery. Vol. IX. No. 2. Svo. New York 1888. The Editors. Medico-Legal Journal (The) Vol. V. No. 3. 8vo. New York 1887. The Editor. Mittheilungen aus der Zoologischen Station zu Neapel. Bd. VIII. Heft 1. 8vo. Berlin 1888. Dr. Dohrn. Revista do Observatorio. Anno III. Num. 3. 8vo. io de Janeiro 1888. Imperial Observatory, Rio de Janeiro. 220 Dr. J. Monckman. Occluded Gases and [May 31, — Revue Médico-Pharmaceutique. Année 1. Nos. 1-3. 4to. Con- stantinople 1888. The Editors. Symons’s Monthly Meteorological Magazine. December, 1886. 8vo. London. Mr. G. J. Symons, F.R.S. Three Autograph Letters of Sir Joseph Banks, P.R.S. Mr. J. W. L. Glaisher, F.R.S. May 28, 1888. Professor G. G. STOKES, D.C.L., President, in the Chair. The Croonian Lecture—‘‘ Ueber die Entstehung der Vitalen Bewegung ”—was delivered by Professor W. Kiihne, of Heideiberg, in the Theatre of the Royal Institution. [Publication deferred. ]} May 31, 1888. Professor G. G. STOKES, D.C.L., President, in the Chair. The Presents received were laid on the table, and thanks ordered for them. Mr: George King (elected 1887) was admitted into the Society. Pursuant to notice, Professors Edmond Becquerel, Hermann Kopp, Kduard F. W. Pfliiger, and Julius Sachs were balloted for and elected Foreign Members of the Society. The following Papers were read :— I. “ On the Effect of Occluded Gases on the Thermo-electric Properties of Bodies, and on their Resistances; also on the Thermo-electric and other Properties of Graphite and Car- bon.” By James Moncxman, D.Sc. Communicated by Pro- fessor J. J. THomson, F.R.S. Received May 1, 1888. “Te Roux has shown that when a notch is filed into a wire and one side heated there is in general a thermo-electric current. Healso found that when two wires of the same metal, with flat ends, are 13888. | the Thermo-electric Properties of Bodies. 221 pressed together, so that one forms a continuation of the other, and the wire on one side of the junction is heated, no current is obtained, but he observed a current in all cases where there was dyssymmetry.” When repeating these experiments, I was led to commence a research: on the effect of occluded gas by the following curious phenomenon. Two pieces of platinum wire of 0°9 mm. section, and of 925 mm. length, were stretched with weights only just heavy enough to keep them straight. They were placed at right angles to each other, the centres _ being in contact, and the ends bending down into mercury cups (see fig. 1). Hach wire after being carefully annealed was joined up to a Fig. 1. galvanometer, and the absence of currents from strain proved by heating with a small flame. When both wires were found to be _ perfectly free, they were brought together in the middle, and one end of each connected with the galvanometer. On heating the wires near the point of contact thermo-electric currents were produced, but after heating the junction of the wires to a bright red for a little time and allowing it to cool, the currents produced by heating the wires on either side were opposite in direction to those produced before. After resting from Saturday until Monday the change in the wires, produced by heating the point of contact, was found to have disappeared, and the currents produced by heating the wires to be the same as at first. ; This naturally suggesting that some ‘kind of temporary change took place in the wire, when heated in a Bunsen lamp, and that this might possibly be produced by the gas absorbed by the platinum at a high temperature, I was induced to commence a series of experiments on the effect of occluded gases on the electrical properties of bodies. A piece of platinum wire about 18 inches long was bent in the middle, and one-half protected by being covered with glass tube and made water-tight at the lower end. After annealing the free portion and testing until perfectly free from all strain effects, it was placed, 222 Dr. J. Monckman. Occluded Gases and {May 31, Fig. 2. up to about the middle, in acidulated water, and made the negative pole of a battery, and hydrogen liberated upon it for a few minutes. After being dried it was tested with a small flame at distances of 1 cm. along its whole length. The result was a current from the free wire towards that part on which hydrogen had been produced, greatest at the junction of the free wire and the saturated wire. A: Free wire. The deflections were.....- 0.) 0:00 F100) ) 10% ee. Another experiment gave.. 0.0. 5. 5.5. 8 8. 5. 5. 0. 0. 0. When wires of palladium were used more powerful effects of the same kind were produced. Thus when two wires were used as the electrodes in decomposing acidulated water, dried and gently heated in contact, a current towards the hydrogen was observed. If heated by a Bunsen flame complications arose from the hydrogen in the wire taking fire. The flame produced could easily be seen 4 or 5 mm. away from the Bunsen flame. Carbon rods were next tried. Gas-carbon was first tried, but I was unable to get two rods sufficiently similar in composition to be of use, their own thermo-electric currents being large enough to cover all changes produced by gases. I had, however, no difficulty in getting rods made for arc lamps to answer my purpose. They were heated to a red heat to expel gases, and the ends were filed flat. It was found that when one of these rods was heated and placed against the other (see fig. 3), the current was always from cold to hot below 200° C. : They were then used as the electrodes in decomposing dilute sulphuric acid, dried carefully until no current was produced on placing 1888. | the Thermo-electric Properties of Bodies. 223 Fig. 3. them in contact. On heating either rod and joining them as before, a current was produced from hydrogen to oxygen across the hot junction. The same effect was obtained by decomposing hydrochloric acid solution, in which case we get chlorine instead of oxygen, and the current flows from hydrogen and chlorine. If the rod be saturated with SO, it is found to act like those containing oxygen or chlorine. © Resistance.—In the first experiments made to try if any change of resistance took place when wires are saturated with gas, a platinum wire about a yard in length was formed into a spiral, and each end soldered to an insulated copper wire. The junctions were covered with wax, and the wires, carefully insulated with wax, passed through two holes ina cork into a bottle containing dilute sulphuric acid. ‘Through the same cork there passed a thermometer and two glass tubes. The whole was placed in a large vessel of water. After having saturated the wire with hydrogen, the acid was drawn off, and air drawn through for some time. The resistance was found to increase slightly on testing. To get rid of possible error from change of temperature, two wires of equal length and section were used and balanced against each other (see fig. 4). Fie. 4. These were placed in water, and a current passed from the one to the other, allowed to remain in the acid a little to cool if necessary, and afterwards removed, dried, and placed in an empty glass vessel surrounded with a considerable quantity of water. There they rested until the temperature became the same as the water. When measured 224 Dr. J. Monckman. Oceluded Gases and [May 31, the resistance of the wire containing the hydrogen was found to have increased about one-thousandth part. It is not necessary to try the effect of hydrogen on palladium, as the resistance is known to be increased considerably by the absorbed gas. Carbon.—Two thin rods about 2mm. diameter were electroplated at the ends and soldered to insulated copper wires. After protecting the plated portion with marine glue, the whole was fixed to a convenient frame, and placed in dilute sulphuric acid. As was done in the case of the platinum wires, the rods were balanced against each other in order to eliminate changes of temperature, &c. When used as the poles of a battery the change of resistance was considerable, but greater on the rod that had been the positive pole. By using a platinum electrode, hydrogen or oxygen was produced at will upon the same rod, the other rod remaining unchanged. It then appeared that oxygen increased the resistance much more than hydrogen, rising in some cases as high as nine times; that when oxygen was liberated twice or thrice in succession, the resistance increased each time. This continued increase was probably due to chemical changes produced by the active oxygen. Hydrogen gave an increase of resistance, not continuing beyond a certain point, and not becoming greater on repeated charging with the gas. Generally also the effect of the hydrogen was temporary, disappear- ing, wholly in some cases, partially in others, when short circuited. The following series of observations afford an example of this :-— 1. When rod A was charged with oxygen its HESISUAMCE WHS cp .e eis oie ole sini eeus eee 4°15 ohms. 2. When rod A was charged with hydrogen its Tesistance Was <4. .4'. 0h. bee + oe cee 41633 ,, 3. When rod A was charged with hydrogen its PESISTANICE WAS ge.ccitttienerencperoace iil 4/1633"; 4. When rod A was charged with oxygen its resistance Washes veeiiien etc scm 4 arene. 42830 > 5, 5. When rod A was charged with oxygen its TESistaNnce WAGs Aieicned s kere ene meee 42966 ___,, 6. When rod A was charged with hydrogen its YesistaNnCe WASiae Wiel eh Cure telels eevee AS09899) =; 7. Allowed to: rest/shorpicircuiteds: 1a) eee: 42966 ,, 8. Again charged with hydrogen............ 4°3066 __,, 9. Allowed to restric wake dee eelin ea aninim s 4303 In the case of hydrogen, the increase was 0°0133 ohm in two experiments, and 0:01 in the other, while it recovered completely after observation No. 6 and partially after No. 8. Superposition of Polarisations—Part of the change in the carbon is evidently produced by the mechanical action of the gases evolved, | 1888. | the Thermo-electric Properties of Bodies. 225 and by the chemical action of the oxygen; both of these will, however, produce permanent changes. That only part of the action is to be explained in this way is shown by the previous experiments. It is, however, further demonstrated by using two carbon rods in decom- posing acidulated water; after passing the current for one minute, reverse it for one-tenth of a second and immediately join up to a galvanometer. A short but violent deflection appears for the latter contact, gradually falling to zero and passing to the other side, where it remains for a considerable time, though with much decreased quantity. The same thing was obtained with platinum electrodes. The second contact must be very short, or the former polarisation disappears. I have not yet succeeded in obtaining more than one reversal, although I have no doubt that more may be got with very thick electrodes. Resistance.—Copper and iron absorb hydrogen and silver occludes oxygen, but no change in their thermo-electric properties could be detected. Carbonic oxide is absorbed by iron, and is said to produce great changes in its properties. In this case, however, only the resistance was measured. A piece of iron wire, about 3 yards in length, was twisted into -a spiral and placed in a porcelain tube; the ends projecting about 3 inches, were connected with one side of a bridge and balanced against an equal spiral of the same wire. After exhausting the tube about 1 foot of the central portion was heated to a bright red- ness and then allowed to cool. Next day the resistance was measured, and the experiment repeated twice. On the third heating, carbonic oxide was allowed to enter the porcelain tube, and readings of the resistance taken on cooling as before. . This was also repeated. This series was again repeated with new wires, and lastly, the wire was raised toa bright red m vacuo and allowed to cool, the object being to remove the carbonic oxide gas in order that another measure- ment might be taken after these repeated heatings. The resistance fell, clearly proving that part of the previous increase was due to the presence of the gas. No measurement of resistance was taken on the same day that the wires were heated, but at least 15 hours were allowed to elapse. First series of observations give the numbers thus :— Average of three measurements after heating in vacuo, 0'4 ohm. ”? bP) +) 9 in car- bonic oxide, 0°41 With the new wire— Average of three measurements after heating in vacuo, 0°63 ” ” » ”? in car- bonic oxide, 0°655 After heating in vacuo to expel the gas, it fell to 0°642 226 Dr. J. Monckman. Occluded Gases and [May 31, These experiments appear to prove that absorbed gases increase the resistance of conductors, and that hydrogen renders metals more negative (thermo-electrically) whilst carbon becomes more positive. I have introduced the experiment (fig. 1) which caused this work to be undertaken, although I do not think that it is entirely caused by the occlusion of gases, where the best results are obtained by electrolysis which produces them in a nascent or more energetic state. Thermo-electric and other Properties of Graphite and Carbon. In making the previous experiments, I had occasion to place the heated end of one carbon rod in contact with the cold end of another. The temperature of the hot end was varied from 30° C. to a red heat, whilst the cold end was kept at about 17° C. Currents of electricity were of course produced. When the tem- perature of the hotter rod was raised but slightly, the current was - from cold to hot through the point of contact, but when it was raised to ared heat the current passed from hot to cold; between these temperatures the direction of the current varied, appearing at first sight to obey no rule, and as nothing was known that would explain these results, I was led to examine the matter more carefully. There were several difficulties to be overcome before any satisfac- tory results could be obtained. Firstly, it was necessary to get two rods of such pure material, that they would not produce a current when placed in contact end to end and heated, or at any rate weak enough to be neglected in presence of that produced by the contact of the two rods at different temperatures. J tried several specimens of gas-carbon, but as no two pieces were found to fulfil the condition before mentioned, they were useless. I was more fortunate with the rods prepared for arc lamps in electric lighting, readily finding two that answered my purpose. A small portion of one of them gave on combustion less than one part of incombustible matter in 200 of carbon. They were heated repeatedly to a red heat and allowed to cool slowly. The ends were filed flat to prevent difference of shape producing any current. When placed in contact end to end and heated, one rod was slightly positive to the other, but not sufficiently to prevent the experiments from succeeding. Secondly, the manner of making contact caused the currents to vary much in strength, and the surface of the heated rod required filing at intervals, in order to preserve a clean flat face. It was found also that the heat of the hot rod passed so quickly to the cold one that even after a very short contact the current fell, so that the rods could be placed together once only and for a very short 1888. ] the Thermo-electric Properties of Bodies. 227 time; after which they require to be brought back to their original temperature. ' Lastly, to avoid any possible effect from the coal-gas, the end to be heated was inclosed in an iron tube lined with asbestos. The temperatures were measured in various ways. In some experiments an ordinary thermometer was used for temperatures below 250° C.; thermo-electric couples of platinum and copper, silver and copper, were tried, but, although much more tedious, I found the method of platinum wire much less liable to error. The wire was given to me by Mr. H. F. Callendar, M.A., and was from the same piece as that used by him in his experiments on “The Practical Measurement of Temperature” (see ‘ Phil. Trans.,’ vol. 178 (1887), p. 161). The following equations for this wire were used in determining the temperature, and are those obtained by Mr. Callendar in his experi- ments :— Ré y Ro — 1} + 000346 Pt. O [ay OM = aatie fg Vest t : Pe = 1574 (55) 00} Ré = resistance of the platinum wire at ¢° C. R? = 99 99 oP) 0° C. The wire was arranged as in fig. 5, by which means the resistance of Fra. 5. BEE alone could be obtained by observing those of AC, BD, CD, and AB; also AB arid CD were known if required, which indeed was the case of one of the later experiments. In some cases the insulation was thin tubes of hard glass, in others the wire was wrapped up in thin sheet asbestos. The arrangement ‘is shown in figs. 6 and 6a, where A and B are the carbon rods, C an Fia. 6. iron tube lined with sheet asbestos, H, H packing of asbestos, D a thermometer for moderate temperature and to test the calculations VOL. XLIV. R 228 Dr. J. Monckman. Oceluded Gases and [May 81, Fig. 6a. from the platinum wire, I’, F platinum wire insulated ; W a vessel of water containing a brass tube H, closed at one end, in which the carbon rod B is placed after each contact. During the first series of experiments the temperature of W, and hence of B, was 16° C., that of A was changed in each contact, rising to 480° C. and higher. At about 480° the deflection changed ; decreasing on approaching that temperature, and changing sign above it. Iam sorry to say that the difficulty of obtaining the same perfection in each contact was so great that the deflections, although increasing above 480°, were not sufficiently consistent to allow a curve to be drawn. Therefore, assuming that the neutral point was midway between that of the two rods when no current was produced (%.e., 16° C, and 480° C.) we get 248° C. for the temperature of that point. B being kept in the second series at 50°, in the third at 100°, and in the fourth at 200°, and the same assumption made in the calculation as before, 255° C. was given as the neutral point. If we now rule a line such that any two points being taken in it, the current shall be equal to the vertical distance between them, and shall flow from the higher point to the lower, it will have its lowest point at from 248° to 255°, rising to 0° and 480° and above (see fig. 7). This assumes that the two lines are equally inclined, and from the experiment with a platinum-carbon couple we judge them to be so, and their turning point to be 250° C. From the preceding experiments I was led to expect that the line of carbon in a thermo-electric diagram, in which the area of the space between the lines is proportional to the electromotive force, would show a bend of some kind, and as no researches were known showing such a bend, it appeared desirable to test it carefully. There is a paper by HE. Becquerel in which he gives an account of a 0009 ol , OO | | | | 00¢ | OOO0Ir 00S I Tt so ICA + - jo pba fey AL e- Sa fe De pied io , ppt tt 1005 vé8. 0002 tt PS CS Ned Sal cal fh | eae eS opt on | } “a ho 4 | } +10 00 2 00S2b+—+-+-++-}- cn eee on Oe es 5 tS tafe 00g2 if Bod vés O o0ogk rs t 1 —}—- peat } - 4 fea et ened een . ~}- +1 . a cil he a ke 1 1000¢ oose | ' . i — drouneh ~}-—1-—- | _- - [ed ; = ol Fie + = et! ~ ar — _ ere 00S? coos tet tt a ppt ttt tt LL 00 OOSP (ore) OS\ 000s 00072 x S 0066 0009 ~~» ~ i) > x S a S) S ?) mw > om) S Gs = La = i) Dad ~ i 0008 } a Ee ES an | ae el fae HN Na a — S| es Ber 00S8 | Je! So |_| 2 + ——| + | IE ala ea L Le — ene al Lov, Ls “ss # : : | 21L 7) b4-7- rr 4 See 7] rf | | | | A ON ERR meen mics “UOYAIAD -O AS 2107 COGLOD \ 0006 rt el Pt man af “ va Be | | | | 7p uw 7) oul \/ ‘O° 4 J | 00Gb 000” 9096 s00¢ 20S 002 OSI /00l qe I | | | | IDM JIPQIOUMNIY, J, \SAODIND DI L/ O'ofr ee ee | - er Cs ee a | on es a eS ee ee ee ee : , — 000 0 9704 Ali aon o00G 00S6 1888.] 230 Dr. J. Monckman. Occluded Gases tnd [May 31, number of experiments with various bodies, among which is gas- carbon. The hot junction was 100° C., at which temperature the deflection produced by a couple (carbon and copper) was negative, the same as copper-platinum, but a little larger. He does not appear to have worked at higher temperatures (‘ Annales de Chimie,’ vol. 8, 1866, p. 415). | Knott and MacGregor also worked with gas-carbon, and in 1879 published a paper in the ‘Transactions of the Royal Society of ‘Edinburgh,’ vol. 28, in which a line for carbon is given. The material was in the form of a cylinder 15 cm. long, 15 em. thick. A strong heated wrought-iron tube, 4 inches long, 2 inches diameter, and l-inch bore, closed at one end, was suspended over the junction and allowed to cool gradually. From 230° downwards the line is parallel to that of platinum. Above 230° it appears somewhat uncertain; they speak of it thus :— “For a small range of temperature (to 230° C.) it is possible to express the deflection in terms of the first and second powers of the temperature, the following formula holding good: 6 = —8:29 + 0°604¢ + 0°000385 ¢?; above 230° C. it does not, perhaps because of chemical changes, produced by heat. Carbon appears to be an excep- tion to the general law.” ‘“‘ The above formula and the graphic treatment enable us at a higher temperature to determine its posi- tion” (see fig. 8). The position and slope of the lines are opposite to those now used. Such a result did not appear to agree with the experiments already described, and as I had found gas-carbon a very unsuitable body for use where two pieces were required having anything like the same thermo-electric power, it appeared probable that good results might be got with the other rods; and as carbon and platinum form for 230° parallel lines I decided to use a couple consisting of these two bodies. Nine series of observations were taken, using three different methods, of which it will be sufficient to describe the last. Near one end of a carbon rod a hole, about 5 mm. in diameter, was drilled, and into this the end of a platinum wire was inserted and fixed by being wedged with a piece of rod carbon. The whole was thoroughly covered with Indian ink, which, when dry, was again Fig. 10. ae XJ 1888.] the Thermo-electric Properties of Bodies. 231 covered with clay. The carbon rod was insulated from the platinum wires, and they from each other by thin sheet asbestos and mica, by which means it was insulated from the vessel in which it was placed, and luted with clay to prevent access of air (fig. 10). The numbers obtained in three series are— Expt. 1. Expt. 2. Expt. 3. E. in micro- t. volts. iB EK. te HK. Bo aes! 270 2908 8S 37 OSPBOO UOMO), STORE IOV PO.) 450 B44 2... 8240 SE OR ORs 2 oe 540 499-22... 5Y60 BALPAY oe" BZO2Fe |) (ies 720 G20" APP 7560 Gap? Vo? S154 P2008)... 900 700 .... 9900 722 .... 9990 a0") .b2. 1260 180 .... 1440 Bi ...: | 1620 The colder junction was at 17° C The resistance of the Pt-C eaniie was found to vary, increasing to 600°, after which it decreased. This result being caused by the increased resistance of the platinum being partly neutralised by the diminution of the resistance of the carbon, to which must be added the improved contact obtained by the expansion of the platinum in the carbon, which is greater than the expansion of the carbon, thence the pressure increases and the contact improves. The numbers were at 220° C. 0°88 ohm, 340° to 500° C. 0:92 ohm, C207 rt Oe, 700° C. 1-00. These experiments agree meeoctly with the diagram given by Knott and Macgregor (fig. 8) as far as they carried it experimentally. When, however, they commence deducing results for higher tempera- tures, our experiments are not in accord; there being no indication of the carbon line crossing the platinum line, but only a very slight indication in one of the series of an approach above 230°. Assuming the platinum line for our wire to be the same as that given in Tait’s diagram (Fleeming Jenkin, p. 178) we get a diagram for carbon (fig. 84), in which the line is fairly parallel to 250° C., after which it gradually increases its distance. Other Changes in the Properties of the Body at the same Temperature. This change in the thermo-electric power of carbon is accompanied by other changes. The resistance, the expansion, and the specific heat all appear to undergo a corresponding alteration. Resistance.—Accurate measurements of the resistance of carbon at high temperatures are very difficult to obtain, owing to the changes that take place in the connexions. It is desirable, if possible, 232 Dr. J. Monckman. Occluded Gases and [May 31, that the whole rod should be exposed to the same temperature. If the rods are thick the changes in the contacts, even at ordinary tem- peratures, become great in proportion to the resistance of the rods; and if thin there is great danger of them being changed by the heat. We found the method of electroplating with copper very good up _to 500° or 600°, after which it completely broke down, and we were not able to get any other method to stand. Thus the experiments were stopped there, although we expected other changes at 800° to 1000°, from the numbers obtained for the specific heat by Weber. The first method tried was that used by H. Muraska (‘ Annalen der Physik und Chemie,’ vol. 13, 1881, p. 310), in which a hole is drilled in each end of the carbon rod, and after electroplating with copper, a copper rod is pushed in tight and brazed in. The ob- jections to this method were: Ist, requires a thick rod; 2nd, better contact formed as the temperature rises, tending to produce error in the same direction as the results of the experiments. — Second. Forming a contact that would be liquid at all tempera- tures above 100°. This was done by drilling vertical holes near the ends of the rods, and filling them with fusible metal. Required thick rods, gave way. Third. Used thin rods so that the change in contact resistance might not bear so large a proportion to that of the rod itself. Glass vessels shaped as in fig. 11 were prepared, and the rod packed at A Fie. 11. and B with asbestos. Fusible metal or solder was melted into the glasses, and the rod protected by a glass tube B. Fourth. An attempt was made to form contacts by inserting the — thin rod into cavities drilled into thick rods of carbon, and joining _ by Indian ink, sugar and graphite, &e. Lastly, the rod was incased in thin sheet asbestos, well coated with wet clay between each layer. The ends were electroplated with copper and tinned. They projected beyond the asbestos covering Fra. 12, 1888. | the Thermo-electrie Properties of Bodies. 233 about 4inch. The glass tubes in the previous method were imitated in asbestos, and into the spaces S, S solder was melted, and thick copper wires inserted, the other ends of which were kept cool by water. When taking observations at high temperatures it is better to cover this with a glass tube at the portion AA. Out of a large series of readings we give four. Graphite Rods.—These rods were supplied by Hogarth and Hayes of Keswick as pure natural Cumberland graphite. Length, 72 inches; diameter, 0°155 inch. Hixperiment 1. "Time of observation. Temperature. R. in ohms. 10 a1" 42°3 12.15 600 23°8 12.25 412 29°7 12.50 278 33°72 3.909 21 42°3 Experiment 2. 1] a.m. 22° 30°4 12.50 155 27°0 2.55 202 26°2 4.30 278 25D 5.54 390 23°2 Next day, 10.45 2, 31:0 Carbon Rods.—Carbon rods supplied by Woodhouse and Rawson, Victoria Street, London. Very hard and good, 12 inches long; diameter, 0°22 inch. Experiment 3. Time of observation. Temperature. R. in ohms. =, eee GA) wedg octwe Av75, 2) ee Os! cata dy Dues 4°75 Beery V5) Rie ha. 0% DOB iene. ss 4°81 Re 3 fort’ ures POs dab 4°85 et ee ee Pigs lyn o*stai bbe 4°88 MeerenylOAM. was... ee ee 52 Experiment 4 IA Eieslist viialovcws . 825 jeui soley. 4°74 Be is 4) Latins. a Syai Bo.nsoe: 4°83 PBOraoier ocd. 008304 B23 Min, sion 4-90 BY bare: CA eueys as 200 of oad 4°98 Next dayllam. ........ 22 234 Dr. J. Monckman. Occluded Gases and [May 31, Changes per 1° C. per 1 ohm— Expt. 1 gives— 21 10 0009 Expt. 2 gives— 22 40 0008 arp y0 00068 seat) 000878 “193000070 o7gt 0 00038 go 10 00076 391 10 00052 Expt. 3 gives— sot 00031 Expt. 4 gives 224 00031 SG }0 “00025 p73 fl (00026 sot 000195 $0 -00030 29850. 325 3730 00082 All showing a decrease (in the temperature coefficient) to about 250°, and then an increase. This method cannot lay claim to absolute accuracy, as there is in some cases an increase of resistance by the change in the contact of copper with carbon, which appears when the rod cools as in Experiment 2. This, however, takes place at the higher temperatures, and tends to decrease the numbers obtained at those temperatures, and a correction, if one could be applied, would only increase the results obtained in the previous experiments. Coefficient of Hxpansion. Method.—As we wished to raise the rod to 500° or 600° C., it was impossible to expose the whole rod to that temperature, and at the same time to read the changes of position of a mark or point at the end of it with a microscope; nor did it appear probable that contact could be made by rods of other materials. It was decided, therefore, to heat the central portion of a rod, keeping the end portions cold. We had thus one hot portion, two colder, and two others at a constant temperature. A rod, about 36 inches in length and $ inch in diameter, was used. One end was electroplated and then soldered into a cavity in a brass rod which was firmly clamped to a vertical iron one fixed to a stone table. Into a small hole in the other end a fine needle was fixed whose change of position was read by a microscope. The central portion of the carbon was covered with a thin coating of clay, then with paper to consume the oxygen, outside that a glass tube packed with asbestos inside of a porcelain tube. Ten inches of the centre of this was heated in a gas furnace. The temperature was taken with a platinum thermometer (fig. 5), HF giving the temperature of the hottest part, AB and CD those of the portions between the hottest and the constantly cold portion. 1888.] —s the Thermo-electric Properties of Bodies. 235 EF was 10 inches, AB and CD 7 inches each, total 24 inches. Outside the rod was kept cool with water. _ In ealeulating the portion of the expansion due to the parts AB and CD the numbers obtained in Hxperiment 4 are used. The expansion is assumed to be regular up to 143°, the number obtained from this is used for the cooler portions AB and CD up to 98°; above that, the number found in the same experiment for the expansion between 143° and 263° is used. One example will show what is meant. In Hxperiment 4, observa- tion 1, we have— Joe 54°) 5A BOX 7) =e oH 27B rer 29 99—15 = 1J4x*7 = 98 1) Se ee 143 143—15 = 128x10 = 1280 Cold portion 15 Se 1651 0 0075 5 (i 0:0000045. Table showing the Temperature of each Portion of the Rod at each Observation, the total Change in Length, and the Coefficient of Expansion. Cold| Total part. jexpansion. AB. EF. | CD. Coefficient of expansion. in. Expt.1. 180°| 614° | 263° | 13° | 0:057083] 0 00000666 between 13° and 614° » 2. 208|645 | 263 | 14 | 0:059375| 00000066 , 14 ,, 645 3 [101 |300 ; 89 | 15 | 0021041) 0-0000056 ,, 15 ,, 300 » 1 908 | 645 |167 | 15 | 0:°058541} 0-000008 | 300; Saree 541/143 | 29 | 15 | 0:0075 |0-000004 , 15 ,, 148 Exot, 4.2 86 | 263 | 44 | 15 | 0-0183’ | 0-0000077 ,,_-:143_,, 268 Pi. 98 | 282 | 49 | 15 | 0-0216’ | 00000140 ,, 263 ,, 282 194 | 602 | 167 | 15 | 0-0583’ | 0-000009 1 2S2e e602 Nos. 1] and 2 give the average of the whole of No. 4, and part 1 of No. 3 is not far removed from the average of parts 1 and 2 of 4, while part 2 of No. 3 is lower than the number obtained in No. 4. Specific Heat—H. F. Weber gives the following numbers as the specific heat of carbon at various temperatures ; unfortunately for our purpose, no observations are recorded between 250° and 640°. 236 Influence of Occluded Gases on Thermo-electricity. [May 31, Temperature. Specific heat. Rate of change per 1° C. —O0te eps oe 0°1138 Graphite Oe? au. tyre 0-1437! ee Cee ee 0 -00076 Hes? Ties 0 -1990 i Dee 0 -00071 138% GNA ees 0 °2542 : # “a ee 0 00067 2ON FOU Bete 0 2966 ; eres. 0 00063 DEO ES OS 0 3250 a: Se 0 00030 OAM) tee eee 0 4454, Oe oy: 0 006045 322 shisiis) a hehie @) een 0 000083 ALARA ROMPEN 0 467 i The curve, fig. 9, is plotted from these numbers and shows a fairly regular increase in the specific heat with the temperature up to 250° where the line bends; another bend occurs at 650°. Te PVs eis - “50° 0 50100 iat 1 Tl imi aa H i | \ i ae, i Ys i ALY Other changes were looked for at the higher temperature, but the contacts gave way, and no definite results were obtained. In con- clusion I wish to acknowledge my obligations to Professor J. J. Thomson, F.R.S. and to R. T. Glazebrook, F.R.S., for much informa- tion and advice during the whole course of the work. Summary of Results. A. Effect of contact of hot and cold car- bon. B. Thermo-electric line C. Rate of decrease of resistance per de- gree per ohm. D. The rate of increase of the coefficient of expansion. EK. Rate of increase of the specific heat. | Below 250° C. Current from cold to hot. Rises. Diminishes. Increases. Fairly regular. Above 250° C. Current from hot to cold. Falls. Increases. Decreases. Falls to halt. 18388.] Colour Photometry. 237 II. “ Colour Photometry. Part II. The Measurement of Re- flected Colours.” By Capt. W. de W. ABnery, R.E., F.R.S., and Major-General FESTING, R.E., F.R.S. Received May 3, 1888. (Abstract.) In a previous paper we showed how the luminosity of different spectrum colours might be measured, and in the present paper we give a method of measuring the light of the spectrum reflected from coloured bodies such as pigments in terms of the light of the spectrum reflected from a white surface. To effect this the first named of us devised a modification of our previous apparatus. Nearly in contact with the collimating lens was placed a double image prism of Iceland spar, by which means two spectra were thrown on the focussing screen of the camera (which was arranged as described in the Bakerian Lecture for 1886), each formed of the light which enters the slit. The light was thus identical in both spectra. The two spectra were separated by about } of an inch when the adjust- ments were complete. A slit cut in a card was passed through this spectrum to isolate any particular portion which might be required. The rays coming from the uppermost spectrum were reflected by means of a small right-angled prism in a direction nearly at right angles to the original direction on to another right-angled prism. Both prisms were attached to the card. From this last prism the rays fell on a lens and formed on a white screen an image of the - face of the spectroscope prism in monochromatic light. The ray of the same wave-length as that reflected from the upper spectrum passed through the lower half of the slit, and falling on another lens formed another image of the face of the prism, superposed over the first image. A rod placed in front of the screen thus cast two shadows, one illuminated by monochromatic rays from the top spectrum, and the other by those from the bottom spectrum. The illumination of the two shadows was equalised by means of rotating sectors which could be closed and opened at pleasure during the time of rotation. The angle to which the sector required to be opened to establish equality of illumination of the two shadows gave the ratio of the brightness of the two spectra. When proper adjustment had been made the relative brightness was the same throughout the entire spectrum. To measure the intensity of any ray reflected from a pigment, a paper was coated with it and placed adjacent to a white surface, and it was so arranged that one shadow of the rod fell on the coloured surface and the other on the white surface. The illuminations were ls ie 238 Colour Photometry. [May 31, then equalised by the sectors and the relative intensities of the two reflected rays calculated. This was repeated throughout the spec- trum. Vermilion, emerald-green, and French ultramarine were first measured by the above method and then sectors of these colours prepared, which when rotated gave a grey matching a grey obtained by rotation of black and white. The luminosity curves of these three colours were then calculated and reduced proportionally to the angle that each sector occupied in the disk. The luminosity curve of the white was then reduced in a similar manner, and it was found that the sum of the luminosities of the three colours almost exactly equalled that of the white. The same measurements were gone through with pale-yellow chrome and a French blue, which formed a grey on rota- tion, with like results. It was further found that the swm of the in- tensities of vermilion, blue, and green varied at different parts of the spectrum, and the line joining them was not parallel to the straight line which represented white for all colours of the spectrum and which itself was parallel to the base. Since a straight line parallel to the base indicated degraded white, it followed that if the intensity of the rays of the spectrum were reduced proportionally to the height of the ordinates above a line tangential to the curved line (which represented the sum of the intensities of the three colours at the different parts of the spectrum) and were recombined, a grey should result. A method was devised of trying this, and the experiment proved that such was the case. The same plan enabled the colour of any pigment to be reproduced from the spectrum on the screen. The combination of colours to form a grey on rotation by a colour- blind person was also tried, and after the curve of luminosity of the colours had been calculated and reduced according to the amount required in the disk, it was found that the sum of the areas of the curves was approximately equal to the white necessary to be added to a black disk to form a grey of equal intensity as perceived by him. The spectrum intensity of gaslight in comparison with the electric light was also measured, and the amount of the different colours necessary to form a grey in this light was ascertained by experi- ment. As before, it was found that the calculated luminosity of the colours was equal to the white which combined with black formed a grey of equal luminosity. The question of the coloured light reflected from different metals was next considered, and the method of measuring it devised, as was also the method of measuring absorption spectra. The luminosity curves obtained by the old method were compared with those ob- tained by the present method, and so close an agreement between them was found to exist, as to give a further confirmation that our former plan was accurate. A number of pigments that can be used for 1888.] Evolution of Gases from Homogeneous Liquids. 239 forming greys by rotation were measured, and the results tabulated in percentages of the spectrum of white light and on a wave-length scale. Ill. “ The Conditions of the Evolution of Gases from Homo- geneous Liquids.” By V. H. VeEuey, M.A, University College, Oxford. Communicated by A. VERNON HARCOURT, M.A., F.R.S. Received May 5, 1888. (Abstract. ) This paper is conveniently divided into three parts. In part (i) an account is given of the effect of finely divided particles on the rate of evolution of gases resulting from chemical changes; in part (ii) the phenomenon of initial acceleration, as also the effect of variation of pressure on the evolution of gases, is discussed; in part (iil) the case of the decomposition of formic acid into carbonic oxide and water is investigated under constant conditions, other than those of the mass of reacting substances and of temperature. Part I—1lt is found that the addition of finely divided chemically inert particles increases the rate of evolution of gases from liquids in which they are being formed. The effect of these particles on the following chemical changes is investigated: (i) the decomposition of formic acid yielding carbonic oxide; (ii) the decomposition of ammonivm nitrite in aqueous solution yielding nitrogen; (iii) the reduction of nitric acid into nitric oxide by means of ferrous sulphate; (iv) the decomposition of ammonium nitrate in a state of fusion pro- _ ducing nitrous oxide; and (vy) the decomposition of potassium chlorate in a state of fusion producing oxygen. The finely divided substances used are pumice, silica, graphite, precipitated barium sulphate and glass-dust. Part II.—It is observed that, conditions of temperature remaining the same, the rate of evolution of a gas from a liquid is at first slow, then gradually increases until it reaches a maximum and for some time constant rate. From this point the rate decreases proportionally to the diminution of mass. Thisis observed in the cases of the decom- position of formic acid, potassium ferrocyanide, and of oxalic acid by concentrated sulphuric acid, and in that of ammonium nitrate. It has previously been observed in the case of the decomposition of ammonium nitrite in aqueous solution. The same phenomenon repeats itself when the temperature is temporarily lowered and then raised to its former point, and also to a more marked degree when, temperature remaining the same, the superincumbent pressure is suddenly increased. The reduction of pressure from one to a fraction of an atmosphere 240 Evolution of Gases from Homogeneous Liquids. [May 31 ’ produces no permanent effect on the rate of evolution of a gas from a liquid, a decrease of pressure, however, produces temporarily an in- crease in the rate, and an increase of pressure conversely produces temporarily a decrease in the rate. Part III—The case of the decomposition of formic acid into carbonic oxide and water by diluted sulphuric acid is studied with the aid of an apparatus by means of which the temperature is kept constant within one-twentieth of a degree. It is shown that the rate of evolution of carbonic oxide is expressible by the following equa- tion :— log (7 + t) + logr = loge, in which 7 is the time from the commencement of the observations; t is the interval of time from the moment of commencement, and that at which, conditions remaining the same, the interval of time required for unit change would have been nil; ris the mass at the end of each observation, and c isa constant. The results calculated by this hypothesis agree with those observed, whether the interval of time required for unit change is 30 or 960 minutes. The curve expressing the rate of chemical change in terms of mass is thus hyperbolic and illustrative of the law which expresses the rate at which equivalent masses act upon another ; 1/c in each experiment is the amount of each unit mass which reacts with the other per unit of time, when an unit mass of each substance is present. Since then equivalent masses take part in the change, it is reasonable to suppose that at first an anhydride of formic acid is produced thus :— HCO HY Oe: ae HCO as HCO f° ee. The anhydride is unstable, and is subsequently decomposed into carbonic oxide and water, HOOy att CO ¢ © = 2CO + OH, The change may thus be compared to the production of ethyl formate from formic acid and alcohol, eer po+ Oslo = G2 lo + mo. with which it shows several points of analogy. In the original paper the methods of observation and the apparatus used are described in full, and the results obtained are set forth in a series of tables. os gi ei aa . ee : 1888. ] Investigations on the Spectrum of Magnesium. 241 IY. “Investigations on the Spectrum of Magnesium. No. II.” By G. D. Liveine, M.A., F.R.S., Professor of Chemistry, and J. Dewar, M.A., F.R.S., Jacksonian Professor, Univer- sity of Cambridge. Received May 16, 1888. Since our last communication on this subject, we have made many additional observations on the spectrum of magnesium under various circumstances, and have arrived at some new results. Speaking generally, we find that differences of temperature, such as we get in the flame of burning magnesium, in the arc, and in the spark, produce less differences in the spectrum than we had before attri- buted to them. [For instance, the lines which previously we had observed only in the spark discharge, we have since found to be deve- loped in the arc also, provided the discharge occur between electrodes of magnesium.* In making these experiments we used thick electrodes of magnesium, and brought them together inside a glass globe about 6 inches in diameter, fitted with a plate of quartz in front and filled from time to time with various gases. The arc was an instantaneous flash which could not be repeated more than twice without rendering the sides of the vessel opaque with a complete coating of magnesium. It was therefore analogous to an explosion of magnesium vapour. The strong blue line \4481, two pairs about \3895, 3893, and \3855, 3848, the strong pair about 12935, 2927, and the two weaker lines of the quadruple group, namely, \2789°9 and 2797, all come out in the arc given by a Siemens’ dynamo between magnesium electrodes in air, in nitrogen, and in hydrogen. We have observed most of them. also when the arc is taken in carbonic acid, in ammonia, in steam, in hydrochloric acid, in chlorine, and in oxygen. The relative intensities of these lines, as compared with one another and with the other lines of the spectrum, vary considerably under different cir- cumstances, of which temperature is doubtless one of the most important; but none of the spark lines seem to be absent from the arc, and even the blue line 4481, so characteristic of the spark, which we never found in the electric arc taken between carbon poles in a crucible of magnesia even on addition of magnesium, is some- times quite as strongly shown in the arc between magnesium electrodes. There are still several lines of the arc which we have never observed in the spark, such as the series of triplets of wave- length less than 2770, but their presence may be dependent more on the large quantity of incandescent matter in the arc than upon its relative temperature. The observations, however, render doubtful * Compare the appearance of the lines of hydrogen in the arc discharge, ‘ Roy. Soc. Proc.,’ vol. 30, p. 157; and vol. 35, p. 75. 242 Profs. G. D. Liveing and J. Dewar. [May 31, the correctness of the received opinion that the temperature of the spark discharge is much higher than that of the are. The greater mass of the incandescent matter in the arc may be expected to give a greater number of lines, because the gradations of temperature will be less steep than in a smaller mass, and we shall have from the outer part of the mass the light which is emitted at compara- tively low temperatures, while from the inner part we shall get those rays which are only produced by the highest temperatures. More- over, compounds which may be dissociated in the interior of the mass may be re-formed in the outer part, and produce their characteristic emission or, in some cases, absorption spectra. Heat, however, is not the only form of energy which may give rise to vibrations, and it is probable that the energy of the electric discharge, as well as that due to chemical change, may directly impart to the matter affected vibrations which are more intense than the temperature alone would produce. The Bands of the Oaide. The set of seven bands in the green, beginning at about 15006°4 and fading towards the violet side of the spectrum, which we have before attributed to the oxide of magnesium, have been subjected to further observation, and we have no reason to doubt the correctness of our former conclusion that they are due either to magnesia or to the chemical action of oxidation. On repeating our experiments with the spark of an induction coil between magnesium electrodes in different gases at atmospheric pressure, we could see no trace of these bands in hydrogen, nitrogen, or ammonia, whether a Leyden jar was used or not. Nor could we see them at all in carbonic oxide, but in this case the brightness of the limes due to the gas might prevent the bands being seen if they were only feebly developed. On the other hand, the bands come out brilliantly when the gas is oxygen or carbonic acid, both with and without the use of a Leyden jar. In air and in steam they are less brilliant, but may be well seen when no jar is used. When a jar is used they are less conspicuous, because in air the lines of nitrogen come out strongly in the same region, and in steam the F line of hydrogen becomes both very bright and much expanded.* It seems, therefore, that it is not the character of the electric discharge, but the nature of the gas which determines the appearance of the bands; and the absence of * Neither the arc of a Siemens’ dynamo, nor that of a De Meritens’ magneto- electric machine, when taken in a crucible of magnesia, shows these bands, even if metallic magnesium be dropped into it. A stream of hydrogen led into the crucible with a view to cool it does not elicit them. When the arc is taken in the oper. air, and metallic magnesium dropped through it, the bands appear moment- arily, but that is probably the result of the burning of the magnesium vapour out- side the arc.-—-May 23. 1888.] ~ Investigations on the Spectrum of Magnesium. 243 the bands in the absence of oxygen, and their increased brilliance in that gas, leave little room for doubt that they are due to the oxide, or . to the process cf oxidation. It may be assumed that at a sufficiently high temperature magnesia will be decomposed, but magnesia is a very stable compound, a great amount of heat is developed in its formation, and it probably requires a temperature far above that of burning magnesium for its complete dissociation. This is consistent with the appearancerof the bands in the spectrum of the flame of the burning metal, as well as in the condensed spark when the other conditions are favourable for the formation of the oxide, or for its stability when formed. In our earlier observations, we obtained in the visible region nothing but a continuous spectrum from magnesia heated with the oxyhydrogen blowpipe; neither the b group, nor 24570, nor the triplet near L appeared, but at the same time \2852 was not only strong, but was strongly reversed. We now find that this result, so far as it was negative, was a consequence of using too large a mass of magnesia to be adequately heated by the flame. If the piece of magnesia is very small, such as a fragment of the ash of burnt magnesium ribbon, most of the spectrum of burning magnesium is developed in the flame for a short distance from the piece of magnesia. It was not very easy to make these experi- ments successfully. About 3 inches of magnesium ribbon were burnt in air, and the ash carefully heated in the upper part of the oxyhydrogen flame to render it dense. The thread of magnesia so -obtained was held horizontally with its end projecting into the oxy- hydrogen flame so as to approach the boundary of the inner cone, and if the current of gas were not too strong all that was further mecessary was to move up the thread horizontally as the end was worn away. When the magnesia was placed as described, the whole upper part of the flame was of a fine azure-blue colour. Under these circumstances, the flame shows the b group and the magnesium- hydrogen series close to it, the bands in the green, the triplet near L, the triplet near M of the flame of burning magnesium, with the group of bands in that region, and the line \2852. It is remarkable that the proportions in which the oxygen and hydrogen are mixed affect the relative intensities of different parts of the spectrum. In general, both the metallic lines of the b group and the bands of the oxide are easily seen; but if the oxygen be in excess the bands of the oxide come out with increased brightness, while the b group fades or sometimes becomes invisible. On the other hand, if the hydrogen be in excess the bands fade, and the b group shows increased brilliance. _ There can hardly be much difference in the temperature of the flame according as one gas or the other is in excess, but the excess of oxygen is favourable to the formation and stability of the oxide, while excess of hydrogen facilitates the reduction of magnesium and VOL. XLIV. | S " a4") = 244 Profs. G. D. Liveing and J. Dewar. [May 31, its maintenance in the metallic state. As regards temperature, it should be observed that while substances merely heated by the flame, and not undergoing chemical change, are not likely to rise to a tempe- rature above the average temperature of the flame, it will be otherwise with the materials of the flame itself and other substances in it which are undergoing chemical change, and have at the instant of such change the kinetic energy due to the change. In a recent communication to the Society, “‘ Researches on the Spectra of Meteorites,’ Mr. Lockyer has directly connected the appearance in nebule of these bands, namely, “the magnesium fluting at 500” with the temperature of the Bunsen burner (‘ Roy. Soc. Proc.,’ vol. 43, p. 133). That the bands are persistent through a large range of temperature there is no doubt, but we cannot help thinking that Mr. Lockyer is mistaken in supposing them to be produced at the temperature of a Bunsen burner. It does not follow because the bands are seen when magnesium is burntin a Bunsen burner that the molecules which emit them are at the temperature of the flame. In the combustion of the magnesium the formation of each molecule of magnesia is attended with a development of kinetic energy which, if it all took the form of heat and were all concentrated in the molecule, must raise its temperature to very nearly the point at which magnesia is completely dissociated. The persistence of the molecule of magnesia when formed will depend upon the dissipation of some of this energy, and one of the forms in which this dissipation occurs is the very radiation which produces the bands. The character of the vibration depends on the motions of the molecules, which in the case in question are not derived from the heat of the flame, but from the stored energy of the separated elements, which becomes kinetic when they combine. The temperature of complete dissociation of magnesia is very far higher than any temperature which can reasonably be assigned to the Bunsen burner. Nor do the observations we have made on magnesia in the oxy- hydrogen flame appear to us to be inconsistent with the conclusion that the spectrum of the oxide is produced only at a high temperature, as we have a decomposition of magnesia by the hydrogen at the highest temperature of the blowpipe flame, and when hydrogen is in excess little but the metallic lines is visible, because the re-formation of magnesia is, for the most part, the reversal of the former action, and occurs in the cooler part of the flame by the interchange of oxygen between steam and magnesium with scarcely any rise of temperature. On the other hand, when the oxygen is in excess the reduced magne- sium carried up into the flame combines for the most part directly with oxygen, and individual molecules thereby acquire a motion of far greater intensity than they could derive from the average heat of the flame. 1888.] Investigations on the Spectrum of Magnesium. 245 In fact, when chemical changes are occurring in a flame it cannot be taken for granted that the temperatures of the molecules are all alike, or that the vibrations which they assume are the result of heat alone. On the other hand, the temperature of the metal separated from magnesia by the oxyhydrogen flame cannot, we suppose, be at a temperature higher than that of the hottest part of the flame. Weare therefore inclined to think that the metallic lines (b) are manifested at a lower temperature than the bands of the oxide; and the appearance of a line in the position of the first band without any trace of the second band (which is nearly as bright as the first), and without any trace of the b group, is quite sufficient to create a suspicion of mis- taken identity when Mr. Lockyer ascribes the sharp green line in the spectrum of nebule to this band of magnesia. This suspicion will be strengthened when it is noticed that the line in question is usually in the nebule associated with the F line of hydrogen, if it be borne in mind that the spark of magnesium in hydrogen does not give the bands, and that the oxyhydrogen flame hardly produces them from magnesia when the hydrogen is in excess. _ In Mr. Lockyer’s map of the spectrum of the nebula in Orion (loc. cit., p. 134), he has represented three lines in the position of the edges of the first three of these bands. If these three lines were really seen in the nebula, there would be less room to doubt the identity of the spectra; but'the authorities quoted for the map (loc. cit., p. 142) mention only a single line in this position. When the flame of burning magnesium is viewed with a high dispersion these bands are resolved into series of fine, closely set lines. Seven such series may be counted, beginning at the approxi- mate wave-lengths 5006°4, 4995°6, 4985°4, 4973°6, 4961°6, 4948-6, 4934-4, respectively. When a condensed spark is taken between magnesium electrodes in oxygen mixed with a little air, the pair of strong nitrogen lines may be seen simultaneously with the bands, and lying within the first band, the bright edge of the band being some- what less refrangible than the less refrangible of the two nitrogen lines. When the bands are produced by the spark discharge between magnesium electrodes in oxygen or other gas, we have not been able to resolve them into lines, but the whole amount of light from the spark is small compared with that from the flame, and besides it is possible that the several lines forming the shading may be expanded in the spark, and thus obliterate the darker spaces between them, Triplet near M and adjacent Bands. Our former ac¢count of the spectrum of the flame of burning magne- sium included a description of a triplet near the solar line M, and a series of bands extending from it beyond the well-known triplet near 246 Profs. G. D. Liveing and J. Dewar. [May 31, L. As we had not observed these features in the spectrum of the spark or are, and could not trace their connexion with any compound, we concluded that they were produced by magnesium only at the comparatively low temperature of the flame. We have since found that they are not produced by the metal at that temperature only, but are exhibited as strongly, or even more strongly, in the are between electrodes of magnesium. In the latter case they appear concurrently with the line at 4481 and other lines which seem to belong to high temperatures. We must therefore regard them as not only produced at the temperature of flames, but as persistent at temperatures very much higher. The different circumstances under which we have observed this triplet are as follows :— In the oxyhydrogen flame when a very small piece of magnesia is held in it. In this case the outer two lines of the triplet are much stronger than the middle line (13724 about), which in some of our photographs does not show at all. It should be noticed that the least refrangible of the three lines (13730 about) is in general more diffuse and not quite so bright as the two more refrangible lines. Magnesia in the oxyhydrogen flame also gives rise to some bands close to and more refrangible than the triplet, and to another still more refrangible but less bright triplet, in which the lines are set at nearly equal distances from each other, with the approximate wave-lengths 3633°7, 3626°2, 3620°6. These additional bands and triplets are not really absent from the flame spectrum, for traces of them may be seen in some of our photographs of the magnesium flame, but they seem relatively brighter in the oxyhydrogen flame with magnesia, and the longer exposure of the photographic plate in the latter case helped to bring them out. They seem to come out more strongly under the conditions which make both the green bands of the oxide and the b group show well. The triplet near M is also produced when magnesium oxychloride and when magnesium chloride is substituted for magnesia in the oxy- hydrogen flame, and in the former case the more refrangible triplet is developed as well. When carbonic oxide and oxygen are substituted for hydrogen and oxygen, both triplets are developed in the part of the flame near the magnesia, and in this flame the middle line of the triplet near M (13724 about) is as strong as it is in the flame of burning magne- sium. The proper adjustment of the thread of magnesia in this flame is a much more delicate matter than in the oxyhydrogen flame. In fact, we made many experiments which were failures before we succeeded in getting satisfactory results; and latterly, in order to be certain of success, we had to fill a gas-holder with a mixture of carbonic oxide - 1888.] Investigations on the Spectrum of Magnesium. 247 and half its volume of oxygen and burn the gases as they issued from the holder. We have not noticed the more refrangible triplet (13633'7 to 3620°6 about) under other circumstances, but the triplet near M is produced when magnesia is held in the flame of cyanogen burning in oxygen, in the flash of pyroxylin with which magnesium filings have been mixed, or which has been treated with an alcoholic solution of magnesium chloride. It is not only very strongly developed, but shows strongly reversed on our photographic plates, in the spectrum of the arc from a Siemens’ dynamo taken between electrodes of magnesium in oxygen; and most of the accompanying ultra-violet bands of the magnesium flame spectrum are at the same time reversed. It is less strongly, but distinctly, reversed in the spectrum of the same are taken in air, in carbonic acid gas, and in sulphurous acid gas. It appears also if the are is taken in ordinary nitrogen unless great precautions are taken to exclude all traces of oxygen or carbonic acid, when it com- pletely disappears. It is developed also in the flash produced when a piece of magnesium ribbon is dissipated in air by the discharge through it of the current from 50 cells of a storage battery. Also in the spark in air at atmospheric pressure between magnesium electrodes connected with the secondary wire of an induction coil when the alternating current of a De Meritens’ magneto-electric machine is passed through the primary. In two cases, but only two, we have found this triplet, of what looks like one or both of the more refrangible of its lines, developed in vacuous tubes. In both tubes the gas was air. One had platinum electrodes and a strip of magnesia from burnt magnesium disposed along the tube ; the other had fragments of the Dhurmsala meteorite attached to the platinum electrodes. The discharge was that of an induction coil worked in the usual way without a Leyden jar. In each case it is only in one photograph of the spectrum that the lines in question appear. In other photographs taken with the same tubes they do not show. On the other hand, this triplet does not make its appearance in the are from a dynamo between magnesium electrodes in hydrogen, coal gas, cyanogen,* chlorine, hydrochloric acid, or ammonia; nor in the * Tn taking the arc in this way in cyanogen our photographs show the whole of the five bands of cyanogen between K and L well reversed. We have before noticed (‘ Roy. Soc. Proc.,’ vol. 33, p. 4) the reversal of the more refrangible three of these bands against the bright background of the expanded lines of magnesium when some of that metal was dropped into the are between carbon electrodes, but in taking the arc between magnesium electrodes in an atmosphere of cyanogen the bright wings of the expanded magnesium lines near L extend beyond the cyanogen bands, and the whole series of the latter are well reversed.—May 23. 248 Profs. G. D. Liveing and J. Dewar. [May 31, arc from a De Meritens’ machine in hydrogen or nitrogen. It does not show in the spark between magnesium electrodes of an induction coil used in the ordinary way, either with or without a Leyden jar, in hydrogen or in air at atmospheric pressure ; nor in the glow discharge in vacuous tubes with magnesium electrodes when the residual gas is either air, oxygen, hydrogen, carbonic acid gas, or cyanogen. Nor does it appear, except in the one instance above mentioned, in the glow discharge in highly rarefied air in a tube containing either magnesia or a strip of metallic magnesium. A review of all the circumstances under which the triplet near M and its associated bands appear, and of those under which they fail to appear, leads pretty conclusively to the inference that they are due not to merely heated magnesium but to the oxide, or to vibra- tions set up by the process of oxidation. With reference to this triplet, Mr. Lockyer (lee. cit., p. 122) has referred to us as his authority for the statement that at the tempera- ture of a Bunsen burner as ordinarily employed the ultra-violet line visible is that at 373. We do not agree to this as a statement of observed fact, and we cannot imagine how the passage to which Mr. Lockyer refers (‘ Roy. Soc. Proc.,’ vol. 32, p. 202) can be sup- posed to warrant it. The flame we mention in that passage is not that of a Bunsen burner but that of burning magnesium, which may be very different from the former even when the magnesium is burning in the air which is mixed with coal gas in the Bunsen burner. Moreover, whatever the temperature of the flame may be, we have never observed the triplet at 3730 unaccompanied by other ultra- violet lines. In the flame of burning magnesium, as we state (Joe. cit., p. 189), “photographs show, besides, the well-known triplet in ae ultra-violet between the solar lines K and L sharply defined, and the line for which Cornu has found the wave-length 2850 very much expanded and strongly reversed.” We have expended a vast amount of time and trouble over vacuous tubes, and our later experiments do but confirm the opinion which we had previously formed that there is an uncertainty about them, their contents and condition, which makes us distrustful of conclusions which depend on them. Photographs of the ultra-violet spectra given by such tubes tell tales of impurities as unexpected as they are difficult to avoid. Every tube of hydrogen which we have examined exhibits the water spectrum more or less, even if metallic sodium bas been heated in the tube or the gas dried by prolonged contact with phosphoric oxide. Indeed the only tubes which do not show the water spectrum have been filled with gases from anhydrous materials contained in a part of the tube itself; and even when tubes have been filled with carbonic acid gas from previously fused sodium carbonate and boracic anhydride the water spectrum is hardly ever al — 1888.] _ Investigations on the Spectrum of Magnesium. 249 absent. The last traces of the ultra-violet bands of nitrogen are alinost as difficult to be rid of with certainty. Frequently unknown lines or bands make their appearance, and the same tube will at different times exhibit wholly different spectra. This is especially the case with tubes of rarefied gases which oppose much resistance to the passage of the electric discharge such as oxygen. li is no easy matter to prepare tubes for the observation of ultra- violet rays to which glass is opaque. Our plan is to fit a sort of stopper of quartz toan ‘‘end-on” tube (fig. 1). This stopper is a slightly conical piece of rock-crystal with the truncated ends’ of the cone ground plane and polished. It is first fitted to the tube by grinding and then cemented in with some vitreous substance more fusible than glass. Formerly we employed sodium metaphosphate which answered fairly, but latterly we have used fused silver nitrate which is easier to manipulate. In any case it is very difficult to prevent the tubes cracking under variation of temperature, but if the tube does not crack it is as effectually closed in this way as if it were all of one piece of glass. It is obvious that nitrogen, oxygen, and silver might be derived from silver nitrate used as cement and might add their spectra to those of the other contents of the tube. But the stopper does not lie in the direct course of the discharge, and we have not found that the silver nitrate is in general decomposed. The pro- ducts of decomposition would at any rate give well-known spectra. The unknown and variable rays we are inclined rather to attribute to substances derived from the glass, either products of decomposition under the action of the electric discharge, or to matters adherent to - the surface which become detached under some electric conditions, and adhere again when those conditions are changed. We have photographed the spectrum of one tube which had been filled with oxygen several times and exhausted, and which gave a well- marked spectrum containing a number of raysunknown tous. After a time other photographs of the same tube showed an entirely different spectrum, and after a further interval the spectrum was found to be again entirely changed, and finally after a further interval the original spectrum reappeared. Changes in the surface tension between the glass and some adherent film may in this case have facilitated the disengagement of the matter of the film and its after re-adherence. Whatever the cause, such changes of the spectra are none the less confusing and suggestive of caution in drawing our inferences from the phenomena of vacuous tubes. The ultra-violet magnesium lines which we have observed in vacuous tubes with magnesium electrodes, when the induction coil, without jar, is employed, are the triplets at \3837, and the lines 42852, 2802, and 2795. These appear whether the residual gas be air, oxygen, hydrogen, or carbonic acid. When a jar is used we have 250 Profs. G. D. Liveing and J. Dewar. [May 31, obtained also the triplets at Pand 8, the pair about 2935 and 2927, ali the quadruple group near \2802 and the quadruple group beyond, and im one case only, in oxygen, the group near s, described below, and the flame-triplet near M. When no jar is used sometimes only 2852 is to be seen, sometimes 2852 and the strong pair near 2802, and sometimes also the triplet near L. We infer, therefore, that this is the order of persistency of these lines under the cir- cumstances. We have before remarked upon the necessity of avoiding all rubber cconnexions in the construction of pumps employed in the exhaustion of tubes for spectroscopic observation, and we described a modification of the Sprengel pump which we had constructed for this end (‘ Roy. Soc. Proce.,’ vol. 30, p. 499). The warnings of unexpected impurities given by photographs of the ultra-violet spectra of vacuous tubes have shown the necessity of preventing the contact of the mercury employed with the dust and moisture of the atmosphere. Hence we have used in the experiments described in this paper a mercurial pump constructed wholly of glass, and in which the same mercury is used over and over again without being exposed to any unfiltered air. For this pump we are indebted to the ingenuity and skill in glass- blowing of Mr. Lennox of the Royal Institution. The annexed figure (2) represents its construction. A is a reservoir which com- municates by the tube aa, which ascends vertically some distance in order to prevent any mercury being driven into the exhausted tube, through the spiral tube ss, with the tube to be exhausted. B is the reservoir of mercury, to the bottom of which the tube gcc passes through the sealed joint d. The upper part of B can be put in com- munication through the three-way cock H, either with the vessel C or with the outer air through the tube D which is filled with calcium chloride. CO forms a mercury valve, and at its upper part communi- cates through the stopcock F with an exhaust pump by which the pressure of the gas in C can be quickly reduced to a few millimetres of mercury. When this has been done, the three-way cock H is turned so as to cut off the communication betweea B and C and open that between Band D. The pressure of the air filtered through D forces the mercury in B up the tube ¢ until it fills A and the whole apparatus, as high as the bend e, driving all gas before it through the tube f and through the mercury valve C, whence it is carried off by the exhaust. The tube g is very narrow so as to oppose resistance to the passage of the mercury whereby A is filled with mercury as quickly as g. As soon as the last bubble of gas has been driven out of f, the three-way cock E is turned so as to shut the communication with D ‘and open that between Band C. As the pressure of the air on the surface of the mercury in B diminishes the mercury falls both in A and in f, leaving a Torricellian vacuum above it, and, as soon as it 1888. ] Investigations on the Spectrum of Magnesium. 251 has fallen below the end of the tube a, the gas in the tube to be ex- hausted expands into A. The same process is then gone through again and again, whereby the whole gaseous contents of A are each time removed, and if the volume of A be large compared with that of the tube to be exhausted, the pressure of the gas in the latter is very quickly reduced. The bends 6bd retain a little mercury when A is exhausted, and prevent any diffusion from c into A, and from f into c. Hach time the mercury fills the apparatus a small quantity flows over into C, but when it has risen above the opening of the tube connecting C and B, it passes back into B, when the cock E is turned so as to open the communication between C and B. VOL. XLIV. T 252 Investigations on the Spectrum of Magnesium. [May 31, Group near s. _ In their list of lines in the spectrum of magnesium (‘ Phil. Trans.,’ 1884, p. 95) Messrs. Hartley and Adeney have given two lines, X3071°6 and 23046°0, which we had not heretofore observed either in the spectrum of the flame, arc, or spark of magnesium; but in our recent observations we have noticed in many cases a well-marked line which, by interpolation between neighbouring iron lines, appears to have a wave-length about 3073'5, and a pair of narrow bands sharply defined on their less refrangible sides at wave-lengths about 3050°6 and 3046°7, and fading away on their more refrangible sides. We have little doubt that the lines we have observed are identical with those given by Messrs. Hartley and Adeney, notwithstanding that there is a much greater discrepancy between the wave-lengths assigned by them and by us than there is between the wave-lengths we have respectively found for the iron lines in the same neighbour- hood. We have noticed the occurrence of this group in the spectrum of the arc from a Siemens’ dynamo between magnesium electrodes in a variety of gases, in all in fact in which we have examined the arc, except in sulphurous acid’ gas which is opaque to rays of this re- frangibility. Also in the are from a De Meritens’ magneto-electric machine between magnesium electrodes in air, in the flash of a mag- nesium ribbon dissipated by the discharge of a storage battery, in the spark of an induction coil worked in the usual way in air and in hydrogen at atmospheric pressure, and in one instance in the spectrum of an oxygen vacuous tube with magnesium electrodes when a Leyden jar was connected with the secondary wire of the induction coil. On the other hand, we do not see this group in the spectrum of other vacuous tubes with magnesium electrodes or with magnesia in the tube, nor in the spark from an induction coil in air or hydrogen at atmospheric pressure when the coil is worked with a De Meritens’ machine on the primary wire, nor in the flame of burning magnesium, nor in the oxyhydrogen flame with magnesia or magnesium chloride, nor in the arc between carbon electrodes in a crucible of magnesia. The circumstances under which this group is seen and is not seen, do not seem to indicate that its emission is connected with any par- ticular temperatures so much as with the character of the electric discharge, and perhaps also with the density of the magnesium vapour. 1888.] Presents. 253 Presents, May 31, 1888. Transactions. Albany, N. Y.:—New York State Library. Annual Reports. 1884-86. 8vo. Albany 1885-87. The Library. New York State Museum of Natural History. Annual Reports. 1879, 1883-86. 8vo. Albany; Bulletin. Vol. I. No. 2. 8vo. Albany 1887. The Museum. University of the State of New York. Annual Reports. 1885- 86. 8vo. Albany; Historical and Statistical Record of the University, 1784-1884. 8vo. Albany 1885. The University. Baltimore :—Johns Hopkins University. Circular. No. 65. 4to. Baltimore 1888. The University. Boston :—Society of Natural History. Memoirs. Vol. IV. Nos. 1-4, 4to. Boston 1886-88. The Society. Bremen :—Naturwissenschaftlicher Verein. Abhandlungen. Bd. X. Hefte 1-2. Svo. Bremen 1888. - The Verein. Brussels :—Académie Royale de Médecine de Belgique. Mémoires des Concours et des Savants Etrangers. Tome VIII. Fase. 2. 4to. Bruxelles 1888. The Academy. Chapel Hil!, N.C. :—Elisha Mitchell Scientific Society. Journal. Vol. IV. Part 2. 8vo. Raleigh, N.C., 1887. The Society. Danzig :—Naturforschende Gesellschaft. Schriften. Bd. VIL. Heft 1. 8vo. Danzig 1888. The Society. Geneva :—Institut National Genevois. Bulletin. Tome XXVIII. Svo. Genéve 1888. The Institute: _ Liverpool :—Astronomical Society. Journal. Vol. VI. Part 7. 8vo. Liverpool 1888. The Society. London :—Geological Society. Quarterly Journal. Vol. XLIV. No. 174. 8vo. London 1888. ‘The Society. London Mathematical Society. Proceedings. Vol. XIX. Nos. 311-313. 8vo. [London 1888. | The Society. Odontological Society of Great Britain. Transactions. Vol. XX. No.6. 8vo. London 1888. The Society. Photographic Society of Great Britain. Journal and Trans- actions. Vol. XII. No. 7. 8vo. London 1888. The Society. Physical Society. Proceedings. Vol. IX. Part 2. 8vo. London 1888. The Society. Royal Agricultural Society. Journal. Vol. XXIV. No. 47. 8vo. London 1888. The Society. Royal Institute of British Architects. Journal of Proceedings. Vol. IV. No. 14. 4to. London 1888. The Institute. Royal Medical and Chirurgical Society. Proceedings. Vol. II. No. 8. 8vo. London 1888; President's Address, 1888. 8vo. London. The Society. T2 age oo ee ' : 254 Presents. [May 31, Transactions (continued). Zoological Society. Report of the Council. 1887. 8vo. London 1888. The Society. Newcastle-upon-Tyne:—North of England Institute of Mining and Mechanical Engineers. ‘Transactions. Vol. XXXVII. Part 3. 8vo. Newcastle 1888. ) The Institute. Paris :—Société Mathématique de France. Bulletin. Tome XVI. Nos. 2-3. 8vo. Paris 1888. The Society. San Francisco:—California Academy of Sciences. Memoirs. Vol. II. No.1. 4to. San Francisco 1888; Bulletin. Vol. I. No. 8. 8vo. San Francisco 1887. The Academy. Santiago :—Deutscher Wissenschaftlicher Verein. Verhandlungen. Heft 5. 8vo. Valdivia 1887. The Verein. Topeka :—Kansas Academy of Science. Transactions. Vol. X. Svo. Topeka 1887. The Academy. Vienna :—Anthropologische Gesellschaft. Mittheilungen. Bd. XVIII. Heft 1. 4to. Wien 1888. The Society. K. K. Geologische Reichsanstalt. Verhandlungen. 1887. Nos. 17-18. 1888. Nos. 1-5. 8vo. Wien. The Reichsanstalt. Washington :—Smithsonian Institution. Miscellaneous Collections. Vol. XXXI. 8vo. Washington 1888. The Institution. Wiirzburg :—-Physikalisch-Medicinische Gesellschaft. Verhand- lungen. Bd. XXI. 8vo. Wurzburg 1888. The Society. Ztrich :-—Naturforschende Gesellschaft. Vierteljahrschrift. Jahrg. XXXII. Heft 4. 8vo. Ziirich 1887. The Society. Basset (A. B.) : | The strongest of these solutions was saturated with the salt. 298 Mr. G. Gore. On the Change of Potential of a [June 14 Grains. 0-003 0 ‘002667 0 °002334 0002001 0:001668 0 ‘001335 Table IV.—Ditto at 8° C. Volts. 1°1546 Ta 7L 1°0543 1°0943 1-080 1 °0514 Grains. —_—___ 0001001 0 000669 0 :000336 0 °000224 0 °000112 Water. The electromotive force gradually increased with the strength of the solution up to 0°002 grain of the salt, then decreased, and after- wards increased again up to 0°003 grain, and then remained constant until the saturation point was attained. The total increase of electro- motive force was 0-21736 volt. The minimum proportion of chloride necessary to upset the balance of potential of the couple lay between 1 part in 695,067 and 1,390,134 parts. Table V.—HCI in 465 grains of Water at 16:5° C. | Volts. | Grains Volts Grains. 0:15 1 ‘3487 0 °05628 1°1715 0:1407 1°2945 0°04691 bes 0°1318 1 °2459 0 °03754 1:1658 0°1219 1 +2373 0 02816 T8515 0°1125 1:1915 0:01879 1 °1429 0:10314 1°1615 0 :0094.2 1°1286 009377 4 —-— —— | 00844. is 0 -00005 1 -0228 0:°07502 $3 0 0000474 0°9799 0° 06565 i Water. 7 The electromotive force increased gradually with the strength of the solution up to 0:06565 grain of the anhydrous acid, then remained constant until 0°10314 grain had been added, and then increased up to the strongest solution employed. The total increase of electro- motive force was 0°3688 volt. The smallest proportion of the anhydrous acid required to disturb the balance of the couple lay between | part in 9,300,000 and 9,388,185 parts of water. 1888.] Voltaic Couple by Variation of Strength of Liquid. 299 Table VI.—Bromine in 465 grains of Water at 12°5° C. Grains. 20°10 18 -39 16 °68 14:97 13°26 11°55 The strongest of these solutions was a saturated one. Volts. 1°9746 19603 1°9517 1 °9403 1°9317 1°9203 | Grains. 9°84 8°13 6°42 4°71 3°00 The electro- motive force first decreased and then increased almost regularly with the strength of the liquid up to the saturation point. The total amount of increase was 0°18 volt. Grains. it he} HDD bo BO bo BO BO OD HWOrPMWAATASO Se. Ol OR OU Table VII.—Ditto at 16° C. Volts. 1 '8746 1°8173 1°7973 1 °7887 1 -7687 1°7573 ” 1°7458 ” ” Grains. SOCOCOCOCOHRE HS By gradually increasing the strength of the liquid, the electro- motive force at first remained uniform, then increased, remained uniform again, then gradually increased, finally at a rapid rate. The total increase was 0°1719. volt. Grains. Table VIII.—Ditto at 13°7° C. Volts. Grains. Volts. 0 :0004: 1 ‘2888 0°0001235 1°1658 0°0003605 9 0 -000084 L505 0 -000321 1 °2802 0 °0000445 1°1086 0 °0002815 1°2745 ——— —_—. — 0 :000242 1°2459 0 -0000081 0°937 0 '0002025 1 °2316 0 :000005 0:°9084. 0-000163 1°1944 Water. . 2A VOL. XLIV. — > ee See aa NE = . 300 Mr. G. Gore. Chemical Energy of Electrolytes [June 14, By regularly increasing the strength of the solution, the electro- motive force at first increased very rapidly, then with decreasing rapidity, and finally remained uniform. The total increase was 0°38 volt. The smallest proportion of bromine required to upset the balance lay between 1 in 77,500,000 and 84,545,000 parts of water. With each of these substances, and with all others which I have examined, a gradual and regular increase of strength of the solution from the weakest up to a saturated one, was attended by a more or less irregular change of electromotive force. By plotting the quantities of dissolved substance as ordinates to the electromotive forces as abscissa, each substance or mixture of substances in every case yielded a. different curve of variation of electromotive force by uniformly changing the strength of its solu- tion. With a given voltaic couple at a given temperature, the curve was constant and characteristic of the substance. As the least addi- tion of a soluble foreign substance greatly changed the ‘‘minimum- point,” and. altered the curve of variation of potential, both the curve and the minimum proportion of a substance required to upset the voltaic balance may probably be used as tests of the chemical composition of the substance, and as means of examining its state of combination when dissolved. By varying the strength of the solution at each of the metals separately, a curve of change of potential was obtained for each positive metal, but not for every negative one. III. “Influence of the Chemical Energy of Electrolytes upon the ‘Minimum Point ’ and Change of Potential of a Voltaic Couple in Water.” By G. Gore, F.R.S. Recerved June 7, 1888. In a communication to the Royal Society, May 3rd, 1888, on “ The Hifect of Chlorine upon the Electromotive Force of a Voltaic Couple,” and in a subsequent one on ‘‘The Minimum Point of Change of Potential of a Voltaic Couple,’ I have shown that by opposing to each other two currents of equal electromotive force from two perfectly similar couples of magnesium-platinum or zinc- platinum in distilled water, and gradually adding to one of the cells sufficiently minute quantities of a suitable substance, such as chlorine, hydrochloric acid, or a soluble salt, &c., the voltaic balance is not disturbed until a certain definite proportion of the substance has been added, and that the proportion required to be added is excessively small (about 1 in 17,000 millions) in the case of chlorine 1888.] and the Minimum-point, &¢., of a Voltaic Couple. 301 with a magnesium-platinum couple, and extremely different with unlike substances. In the present paper my object is to describe a few similar experi- ments, made to examine the influence of liquids of different chemical composition, upon this phenomenon and upon the degrees of electro- motive force produced by further additions of the substances. All the solutions were made with distilled water, and the substances employed were of considerable degree of purity. ‘The voltaic cell consisted in each case of zinc and platinum in distilled: water, and its electromotive force was balanced by that of a suitable thermo-electric pile (see ‘Proceedings of the Birmingham Philosophical Society,’ vol. 4, p. 130), and the measurements made under that condition. The electromotive force of a zinc-platinum couple in ordinary distilled water at 16° C. is about 1°088 volt; provided the zinc is free from oxide, and the platinum contains no absorbed hydrogen. The presence of hydrogen (not removable by rubbing but removable by heating to redness) may reduce the electromotive force to 0°91 volt, and a film of oxide upon the zinc may reduce it 1 or 2 per cent., whilst carbonic acid absorbed by the water from the air, &c., may Increase it about 2 per cent. In all cases, therefore, where very exact measurements of electromotive force are necessary, these cir- cumstances have to be considered. In the present case the measure- ments are sufficiently accurate for the purposes intended. A series of measurements were made with a zinc-platinum couple in water, adding uniform quantities of hydrochloric acid up to 015 grain per 465 grains of water, and heating the platinum to redness previous to each measurement. The variations of electro- motive force obtained were nearly the same as when the platinum was not heated, the only material difference being that the electromotive force throughout was about 0°10 volt higher. The following are the results of the experiments made upon the influence of the chemical energy of the liquid. The numbers are corrected for the influence of hydrogen absorbed by the platinum. Table IL—KIO, in 465 grains of Water at 15° C. Grains. Volts. Grains. Volts. Gruins. Volts. 87°05 1°40586 22°05 1 ‘26 7°05 1°1456 34°05 1°36296 19°05 1° 2428 4-05 1°1313 31°05 1°3172 16°05 1 °2085 1°05 1°1370 28°05 1 2829 13 ‘0d 1°2028 0°94 1°0884 25°05 1 °27438 10°05 1°14 | water - The strongest solution employed was a saturated one. Four different solutions, each weaker than 0°94 grain, gave the same 2a 2 302 Mr.G. Gore. Chemical Energy of Electrolytes [June 14, electromotive force as water. The least proportion of the iodate necessary to upset the balance lay between 1 part in 443 and 494 parts of water. The increase of electromotive force by increased strength of the solution was nearly regular, as may be seen by plotting the quantities of substance as ordinates to the electromotive forces as abscissee. In order to remove any trace of free iodine, the iodate was previously kept at 100° C. cose one hour; it was then Beeson white and free from odour. Table II.—KBrO, in 465 grains of Water at 14° C. Grains. Volts. Grains. Volts. Grains. Volts 195 1 °2886 | 12 1°260 4°5 1 °3344 18°0 1°2743 10°35 4: 3°0 1°3000 16°5 a 9 1°3344 L*5 1-2600 15 1 °2772 | 7*5 tS : she 13 °5 12972 | 6 _ The strongest solution was a saturated one. Table IIT.—Ditto at 15° C. Grains. Volts. i Liat 1-260 oh PES Lan7 1 °2066 1 °0884 water a Hight other solutions, all of different strengths below 1:2006, gave the same electromotive force as water. The smallest proportion of bromate required to upset the balance lay between 1 in 344 and 387 parts of water. The increase of electromotive force by increase of strength of the solution was extremely irregular. The effects obtained with solutions of potassic chlorate have already been given in the paper on “The Change of Potential of a Voltaic Couple by Variation of Strength of its Liquid.” The smallest proportion of the salt required to disturb the voltaic balance lay between 1 in 221 and 258 parts of water. Three solutions, each weaker than 1°8 grain in 465 grains of water, viz., 0°09, 0°009, and 0:0009 grain, gave the same electromotive force as Water The following table shows the results obtained with this group of salts :— 1888.] and the Minimum-point, §c., of a Voltaic Couple. 303 Table IV. Iodate, minimum point of change lay between 1 in 443 and 494. Bromate, a is 4 1 ,, 344 ,, 384. Chlorate, s - - Dd 1B iarernae 5 Lo The minimum points of change of these three salts constitute a Series indicating a gradation of degree of chemical union of the negative constituent of the salt with its base, feeblest in the iodate, intermediate with the bromate, and strongest in the chlorate. The more feebly united the negative constituent, the smaller was the _ proportion of the salt required to disturb the voltaic balance. Table V.—KI in 465 grains of Water at 15° C. Grains. Volts. Grains. Volts. 1°1252 1°1442 1:1585 1 +1728 73° The strongest solution was a saturated. one. Grains. Grains. 6°00 5°49 Grains. 692 685 678 Table VI.—Ditto at 13°’ C. Grains. | 426 342 258 Volts. 1°1556 ” ) Grains. 174 90 6 Table VII.—Ditto at 14° C. Volts. 1°1556 1°1442 Grains. | 4, 4 89 "29 Volts. 1°0584: 3) Grains. 3°69 3°09 Volts. 1°1556 ” bP) Volts. 1 °0584 ) 304 Mr. G. Gore. Chemical Energy of Electrolytes [June 14, Table VIII.—Ditto at 19° C. Grains. Volts. Grains. Volts. Grains. Volts. 3°0 1°0497 1°68 1-°0669 0°36 1°0697 2°67 1°0588 i635 1 °0583 0:03 1°0716 2°34 1°0697 1°02 1°0697 0:027 1°0812 2°01 1°0726 0°69 5 water m3 The great solubility of the salt rendered several groups of measure- ments necessary in order to include the entire range of solution. The . salt was odourless and colourless, but slightly alkaline. The smallest proportion of the iodide necessary to change the balance lay between 1 in 15,500 and 17,222 parts of water. The variation of electro- motive force with strength of solution was very irregular. The greatest electromotive force was with a solution containing from 680 to 700 grains of the salt. Table [X.—KBr in 465 graius of Water at 12°5° C. Grains. Volts. Grains. Volts. Grains. Volts. 273 1°1442 153 1:2457 33 1-230 243 1°1771 123 1-2314. 3 12337 213 1-2314, 93 11485 q a 183 L-2171 910 Pee 1-230 The salt was well crystallised, dry, odourless, and neutral to test- paper. The strongest solution of it was a saturated one. Table X.—Ditto at 9° C. Grains. Volts. Grains. Volts. Grains. Volts. 0°08 1 +2872 0 -01668 1 °2443 0°00336 1-087 0: 02667 1 °2729 O701335 | 1 3015 water oy 0 °02334 1 °2529 0:01001 | 1°2872 0°02001 1°2443 0 00669 1:1871 vs cm Six different strengths of solution, each weaker than 0-0036, gave the same electromotive force as water. The smallest proportion of the salt which upset the balance lay between 1 part in 66,428 and 67,391 parts of water. | a 1888.] and the Minimum-point, S¢., of a Voltaic Couple. 305 Table XI.—KCl in 465 grains of Water at 12° C. Grains. Volts. Grains. Volts. Grains. Volts. 147 1 °30436 93 1 °30436 39 1 °30436 129 ih "5 i 21 . 111 57 + Fin 39 The strongest solution was a saturated one. Four other solutions between those of 129 and 147 grains were tried, but they all gave 1:30436 volt. The abscissz of the electromotive forces in this table formed a straight line. Table XII.—Ditto at 8° C. Grains. Volts. Grains. Volts. Grains. Volts. 0-003 1°3056 0 001335 1°2014 0 000224. 1°087 0 ‘002667 1 -°2671 0:001L001 1°1728 0°000112 si 0 002334. 1 °2043 0: 000669 1°1442 water ¥ 0 :002001 1 °2443 0:000660 1°087 oP af 0001668 1-230 0 -000336 e | The smallest proportion of the salt necessary to disturb the voltaic balance lay between 1 in 695,067 and 704,540 parts of water. The variation of electromotive force in these solutions was not uniform. _ The followmg table shows the proportions of these three salts required to upset the balance :— Table XIII. Iodide, between lin 15,500 and 17,222 parts of water. Beomide .,,. 1 ,, 66,428:93/07 67.39F° -s, fi Chloride ” 1 Le 695,067 sie 704,540 ” ” By comparing these numbers with those in Table IV, it will be perceived that each of the haloid salts acted much more powerfully than either of the oxygen ones, and that the order of degrees of activity in the two series was reverse. (Suspecting a decomposition of the chloride solution by the couple, I divided a solution of 8 grains of the salt per ounce of water into _ two equal portions in two glass vessels, then immersed a piece of zine wire in one portion, and a second piece of the same wire in contact with a piece of platinum in the other, and set the vessels aside. In about 24 hours the liquid containing the couple was distinctly alkaline, 306 Mr. G. Gore. Chemical Energy of Electrolytes [June 14, whilst the other remained neutral. further. ) The three halogens of the salts were now employed separately. “~ S S Ss = Ry ae Hopkinson. | [Proc. Roy. Soc., Vol. 44, Pl. 3. Cunve II, Induction per square centumelre nines ei | YY . oe TEmMPR 112-8° C 7 | SO PAO. 32 5 SO 60. - Magnelising force Curve III. Induction per square centimelre GO O 40 ~. 350 Magnetising force. Hopkinson. |. [Proc. Roy. Soc. Vol. 44, Pl. 4. Curve IV. Lrcucltoiw per sguore cenlt melre Magnetising force CURVE V. Induction per 2500 30 40 Ma gue fising for "Ce. name wt A a cleo 27 ohn cay yy BRR) He line Hopkinson. | [Proc. Roy. Soc., Vol. 44, Pl. 9. Curve VI. Lnduction per SYUAVE cermtimelre | Curve VII. ~ Lnductton per Ssyuare cenlimelre. 2000 /500 30 40 50 Magreettstrg fore . e a « t , — a Curve VIIL. Induction per square cezitim elre CuRvVE IX. SLnducttor per sguare centimetre. Oo 350 ; 4O : Magnetising force [Pl. 6. —— ny, ek Curve X. 'Lnduction per sguare cen timeere. Magretising force. CURVE XI. Laduction pier: sguare centimetre. 50 O30: ~~, ~~ #0 Magnettstrg force. [Pl. 7. RPE ee Curve XII. Lreductior per SYUAIE CERLLINELTE -_ 50 40 a) Magrettsirg force Curve XIII. Lrductior per sguare centimetre. MP . 20 30. 40 50 Magretising force. Curve XIV. Lrduclion per sgyllare centimelre Magrettstrg force. [ Pl. 8. [Pl. 9. Curve XV. Lnduction per sguare certinelre. 6.000 /0 20 30 40 50 60 | 70 80 90 /00 «(110 Magnetising force. Prt, te: See Hopkinson. | [ Proc. Roy. Soc., Vol. 44, Pl. 10. Curve XVI. Induction per sguare cerilimclre 4500 ) 30.~«:~«SHO 50 Magi {7 SUNY force Curve XVII. Inductvon per square ceritimelre 1000 100 150. 200 MLagnetising Loree = — Sn .. > 2% cad ay Mets = oy a Hopkinson. | [ Proc. Roy. Soc., Vol. 44, Pl. 11. Curve XVIII, Induction per sylare cernlimelre Magnetrstny Force 10. Curve XIX. Induction per square centimelre. Oe —— ‘ ket) ay miah by i e € aye slater fe ata hy “ ne +a Ay ba cre sees ie Hopkinson. | nduction per square certtimelre NY 1 S Q 'a0ung828ad fo aswasIe JO ulelg2snhoT [ Proc. Curve XX. Curve XXI. Roy. Soc., Vol. 44, Pl. 12. PT RE 1888. ] Magnetic Properties of an Impure Nickel. 319 3. The magnetisation of my impure nickel disappears about 310° C. 4. A little below the temperature of 310° C. the induction diminishes very rapidly with increase of temperature. 5. At lower temperatures still the induction increases with rise of temperature for low forces, diminishes for high forces. This fact has been observed by several experimenters. Specific Heat.—The object here was simply to ascertain whether or not there was marked change at the temperature when the nickel ceases to be magnetic. It appeared that this question could be best answered by the method of cooling, and that it mattered little even if it were roughly applied. A cylinder of nickel (fig. 2, Plate 13) was taken, 5°08 cm. diameter, 5°08 cm. high, having a circumferential groove, 15°9 mm. deep and 6°35 mm. wide. In this groove was wound a copper wire, well insulated with asbestos, by the resistance of which the temperature was determined. The cylinder was next enveloped in many folds of asbestos paper to insure that the cooling should be slow, and that consequently the temperature of the nickel should be fairly uniform and equal to that of the copper wire. The whole was now heated over a bunsen lamp till the temperature was considerably above 310° C.; the lamp was next removed, and the times noted at which the Petance of the copper wire was balanced by successive values in the Wheatstone’s bridge. If @ be the temperature, and ¢ be time, and if the specific heat be assumed constant, and the rate of loss of heat proportional to the excess of temperature, k = +0=0 _orklog 6+ (t—t) =0. Incurve 21 the abscisse represent the time in minutes, the ordinates the logarithms of the temperature; the points would lie in a straight line if the specific heat were constant. It will be observed that the curvature of the curve is small and regular, indicating that although the specific heat is not quite constant, or the rate of loss is not quite proportional to the excess of temperature, there is no sudden change at or about 310° C. Hence we may infer that in this sample there is no great or sudden absorption or libera- tion of heat occurring with the accession of the property of magnetisability. 320 Hon. Charles A. Parsons. Experiments on [June 14, VIII. “ Experiments on Carbon at high Temperatures and under great Pressures, and in contact with other Substances.” By the Hon. Cartes A. Parsons. Communicated by the Right Hon. the Fart or Rossz, F.R.S. Received June 13, 1888. The primary object of these experiments was to obtain a dense form of carbon which should be more durable than the ordinary carbon when used in are lamps, and at the same time to obtain a material better suited for the formation of the burners of incandescent lamps. There were a considerable number of experiments made in which the conditions were somewhat alike, and many were almost repetitions with slightly varying pressures and temperatures. They may, how- ever be divided into two distinct classes: the first in which a carbon rod surrounded by a fluid under great pressure is electrically heated by passing a large current through it, the second in which the liquid is replaced by various substances such as alumina, silica, lime, &c. The arrangement of the experiment was as follows :—A massive cylindrical steel mould of about 3 inches internal diameter and 6 inches high was placed under a hydraulic press ; the bottom of the mouid was closed by a spigot and asbestos-rubber packing—similar to the gas-check in guns; the top was closed by a plunger similarly packed; this packing was perfectly tight at all pressures. In the spigot was a centrally bored hole into which the bottom end of the carbon rod to be treated fitted, the top end of the carbon rod was con- nected electrically to the mould by a copper cap which also helped to support the carbon rod in a central position. The bottom block and spigot were insulated electrically from the mould by asbestos, and the leading wires from the dynamo being connected to the block and mould respectively, the current passed along the carbon rod in the interior of the mould. The fluid was run in so as to cover the rod completely. The plunger was then free to exert its pressure on the liquid without injuring the carbon. The pressure in the mould was indicated by the gauge on the press. Experiments. Class I. Among the liquids tested were benzene, paraffin, treacle, chloride and bisulphide of carbon. The pressures in the mould during the several experiments were maintained at from 5 to 15 tons per square inch; the initial size of the rod was in all cases }-inch, and the current from 100 to 300 amperes. a : _ eat - ir 1888.] . Carbon at high Temperatures and great Pressures. 321 Resulis—tiIn some of these experiments a considerable quantity of gas was generated, and the press had to be slightly slacked back during the experiment to accommodate it and maintain the pressure constant. In ail cases there was a soft friable black deposit of considerable thickness on the carbon. In no case was the specific gravity of the carbon rod increased by this process. There was no change in appearance of the fracture, ex- cepting when chloride of carbon had been the fluid; it was greyer-in this case. The rate of burning of samples placed in arc lamps was not diminished by the process. Various rates of deposition were tried, but with the same result, and the conclusion seems to be that under very high pressures, such as from 5 to 16 tons per square inch, the deposit of carbon by heat from hydrocarbons, chloride of carbon, bisulphide of carbon, treacle, &c., is of a sooty nature, and unlike the hard steel-grey deposit from the same liquids or their vapours at atmospheric or lower pressures. Experiments. Class IT. In these experiments the asbestos-rubber packing was omitted, the plunger and spigot being an easy fit in the mould. A layer of coke powder under the plunger formed the top electrical conuexion with the rod. No. 1. Silver sand or silica was run around the carbon rod, and pressures of from 5 to 30 tons per square inch applied; the rod was usually about j-inch diameter, and currents up to 300 ampéres passed. Results——The silica was melted to the form of a small hen’s egg around the rod. When the current was increased to about 250 amperes the rod became altered to graphite, the greater the heat apparently the softer the graphite. There was no action between the silica and the carbon, the surface of the carbon remained black, and there were no hard particles in or on the carbon rod. Other substances, such as an hydrated alumina and mixtures of alumina and silica, gave the same results. The density of the carbon was considerably increased, in some cases from normal at 1°6 to 2°2 and 2°4; in these cases the carbon appeared very dense, much harder than the original carbon, and about as hard as the densest gas-retort carbon. No crystalline structure was visible. The specimens were treated with solvents, and there appeared no indication of the surrounding substance having penetrated the rod ; the carbon was undoubtedly consolidated by 30 per cent. dn some cases when the material surrounding the rod was alumina Carbon at high Temperatures and Pressures. [June 14, arated with oil, soft crystals of graphite exuded from specimens v-at had been kept for some weeks. No. 2. Pure hydrated alumina, carbonate and oxide of magnesia and lime all rapidly destroyed the carbon rod, by combining with it, the hydrated alumina forming large volumes of gas of which it appeared to be a constituent. On account of the great diminution of bulk, no analysis was made; the gas issued from the mould explo- sively at from 10 to 12 tons per square inch. The alumina was found in a crystalline crust, like sugar, around where the rod had been. Hardness that of corundum, almost translucent. No. 3. The following is the most interesting experiment of the series :— é. On the botton of the mould was a layer of slaked lime about d-inch thick, over this silver sand 2 inches, then another layer of lime of the same thickness as the former, finally a layer of coke-dust, and then the plunger. Witha pressure of from 5 to 30 tons per square inch in the mould, and the carbon of from + to ;3, diameter, currents from 200 to 300 ampéres were passed. In from 10 to 39 minutes the current was generally interrupted by the breaking or fusing of the rod, or by the action of the lime in dissolving it at the top or bottom. On opening the mould when it had cooled a little, the silica usually appeared to have melted to an ege- shaped mass, and mixed somewhat at the ends with the lime; the surface of the carbon appeared acted on, and sometimes pitted and crystalline in places; silica adhered to the surface, and beneath, when viewed under the microscope, appeared a globular cauliflower-like formation of a yellowish colour, resembling some specimens of = bork.” After several days’ immersion in concentrated hydrofluoric acid, this formation remained partly adherent to the carbon; on the surface of the carbon was a layer or skin about {,th of an inch thick of great hardness, on the outside grey, the fracture greyer than the carbon, but having a shining coke-like appearance under the microscope. The powder scraped off the surface of the rod has great hardness, and will cut rock crystal when applied with a piece of metal faster than emery powder. It has, under the microscope, the appearance of bort, the minute particles seem to cling together; they are not transparent as a rule, and though some such particles are found among them, it is not clear that such are hard. When a piece of the skin has been rubbed against a diamond or . other hard body, the projecting or hard portions have a glossy coke- like appearance. A piece of the skin will continue to-scratch rock crystal for some time without losing its edge. It will scratch ruby, and when rubbed * The bort-like powder is not acted on by hydrofluoric and nitric acids mixed. --1888.] Presents. 393 for some time against it will wear grooves or facets upon it. When a cut diamond is rubbed on the surface of the skin, it will ect through it into the carbon beneath, making a black line or opening about +-inch long; the facet on the diamond, originally ,-inch diameter, will have its corners evenly rounded, and its polished surface reduced to about one-half its original area; the appearance of the edges is as if they had been rubbed down by a nearly equally hard substance. The subject of the last experiment is scarcely sufficiently investi- gated to warrant any definite conclusions. The substance in the several ways it has so far been tested seems to possess a hardness of nearly if not quite the first quality. The minuteness of the particles, which appear more or less cemented together, and are less cohesive after the action of acid, make it very difficult to determine their distinctive features. The mode of formation is not inconsistent with the conditions of pressure, temperature, and the presence of moisture, lime, silica, and other substances as they appear to have existed in the craters or spouts of the Cape Diamond Mines at some epoch. From the few experiments that have been made it appears that at pressures below 3 tons per square inch, the deposit does not possess the same hardness, though somewhat similar in appearance. What part the lime and silica play, whether the former only supplies moisture and oxygen which combine witn the carbon, or whether the presence of lime is necessary to the action, is not clear. We may, however, observe that so far it seems as if the lime and moisture combining with the carbon form a gas or liquid at great \ pressure, which combining with the silica, forms. some compound of lime, silica, and carbon, or perhaps pure carbon only, of great hardness. Presents, June 14, 1888. Transactions. Albany :—New York State Museum of Natural History. Bulletin. No. 8. 8vo. Albany 1888. The Museum. London :—Photographic Society of Great Britain. Journal and Transactions. Vol. XII. No.8. 8vo. London 1888. The Society. Royal Institute of British Architects. Journal of Proceedings. Vol. IV. No. 15. 4to. London 1888. The Institute. Society of Biblical Archwology. Proceedings. Vol. X. Part 7. 8Svo. London 1888. The Society. Manchester :—Geological Society. Transactions. Vol. XIX. Parts 18-19. 8vo. Manchester 1888. The Society. O24 Presents. [June 14, Transactions (continued). . . Naples :—Reale Accademia di Scienze Morali e Politiche. Atti. Vols. XXI-XXII. 8vo. Napoli 1887-88; Rendiconto delle Tornate e dei Lavori. Anno XXVI. 8vo. Napoli 1887. The Academy. Newcastle-upon-Tyne :—Natural History Society of Northumber- land, Durham, and Newcastle-upon-Tyne. Natural History Transactions of Northumberland, Durham, and Newcastle- upon-Tyne. Vol. IX. Part 2. 8vo. Newcastle 1888. The Society. North of England Institute of Mining and Mechanical Engineers. Transactions. Vol. XXXVII. Part 4. 8vo. Newcastle 18¢8. The Institute. New York:—American Geographical Society. Bulletin. Vol. XIX. Supplement; Vol. XX. No. 1. 8yvo. New York 1887-88. The Society. Paris :—Ecole Normale Supérieure. Annales. Tome V. Nos. 5-6. Ato. Paris 1888. The School. Société Francaise de Physique. Séances. Juillet—Décembre, 1887. 8vo. Paris. The Society. Rome:—Reale Accademia dei Lincei. Atti. Ser. 2. Vol. IV. 4to. Roma 1887; Memorie (Classe di Scienze Morali). Ser. 3. Vol. XII. 4to. Roma 1884. The Academy. Reale Comitato Geologico d’Italia. Bollettino. Nos. 3-4. 8vo. Roma 1888. The Comitato. Observations and Reports. Bombay :—Selections from the Letters, Despatches, and other State Papers preserved in the Bombay Secretariat. Home Series. Vols. I-II. 4to. Bombay 1887. Record Department, India Office. Calcutta :—Meteorological Observations recorded at Seven Stations in India. December, 1887. 4to. [Calcutta]; Description of the Stations. 4to. [ Calcutta]. The Meteorological Reporter, Government of India. Meteorological Department, Government of India. Cyclone Memoirs. Part 1. 8vo. Calcutta 1888; Indian Meteorological Memoirs. Vol. IV. Part 4. 4to. Calcutta 1887; Report on the Meteorology of India in 1886. 4to. Calcutta 1887. The Meteorological Reporter, Government of India. Chemnitz :—K6nigl. Sachsisches Meteorologisches Institut. Jahr- buch. 1886. Abth. 1-3. Ato. Chemnitz 1887-88. | The Institute. — 1888.) On the Physiology of the Invertebrata, 325 Observations, &c. (continued). Glasgow :—Mitchell Library. Report. 1887. 8vo. Glasgow 1888. The Library. Guatemala :—Direccion General de Hstadistica. Informe. 1887. 8vo. Guatemala 1888. The Office. India :—Geological Survey. Memoirs (Paleontologia Indica.) Ser. 18. Vol. I. Part 7. Ato. Calcutta 1887. The Survey. June 21, 1888. Professor G. G. STOKES, D.C.L., President, in the Chair. An Address to the Queen, expressing sympathy with Her Majesty and with her daughter, the Empress of Germany, on the death of the Emperor, was read from the Chair. Colonel Alexander Ross Clarke, Professor Alfred George Greenhill, and Professor John Henry Poynting were admitted into the Society. The Presents received were laid on the table, and thanks ordered for them. The following Papers were read :— I. “Further Researches on the Physiology of the Inverte-' brata.” By A. B. Grirrirus, Ph.D., F.R.S. (Edin.), F.C.8. (Lond. and Paris), Principal and Lecturer on Chemistry and Biology, School of Science, Lincoln; Member of the Physico- Chemical Society of St. Petersburg. Communicated by SiR RICHARD OWEN, K.C.B., F.R.S. Received May 20, 1888. I. The Renal Organs of the Asteridea. The digestive apparatus of Uraster rubens (one of the Asteridea) is briefly described as follows :—The capacious mouth, found upon the under side, leads into a short cesophagus, which opens into a wider sacculated stomach with thin distensible walls. There are five large _ stomach sacs; each of these is situated in a radial position and passes into the base of the corresponding ray. Lach sac or pouch is kept in its place by two retractor muscles fixed to the median ridge of the ray, which lie between the two ampullw or water-sacs. Passing 326 Dr. A. B. Griffiths. [June 21, towards the aboral side, the stomach forms the well-known penta- gonal “pyloric sac.” The pyloric sac gives off five radial ducts, each of which divides into two tubules bearing a number of lateral follicles, whose secretions are poured into the pyloric sac and intestine. The author has proved the nature of their secretion to be similar to that of the pancreatic fluid of the Vertebrata (‘ Edinburgh, Roy. Soc. Proc.,’ No. 125, p. 120). Recently, the secretion found in the five pouches of the stomach (of Uraster) has been submitted to a careful chemical and microscopical examination. With a quantity of the secretion, obtained from a large number of starfishes, the follow- ing experiments were performed :— 1. The clear liquid from these sacs was treated with a hot dilute solution of sodium hydrate. On the addition of pure hydrochloric acid, a slight flaky precipitate was obtained, after standing seven and a half hours. These flakes when examined beneath the microscope (4-in. obj.) were seen to consist of various crystalline forms, the predominant forms being those of the rhomb. On treating the secretion alone with alcohol rhombic crystals are deposited, which are soluble in water. When these crystals are treated with nitric acid and then gently heated with ammonia, reddish-purple murexide is obtained, crystallised in microscopic prisms. 2. Another method was used for testing the secretion. It (the secretion) was boiled in distilled water and evaporated carefully to dryness. The residue obtained was treated with absolute alcohol and filtered. Boiling water was poured upon the residue, and to the aqueous filtrate an excess of acetic acid was added. After standing some hours, crystals of wric acid were deposited and easily recognised by the chemico-microscopical tests mentioned above. The above alcoholic filtrate was tested for urea. First of all, the alcoholic solution was diluted with distilled water, and boiled over a water-bath until all the alcohol had vaporised. The warm aqueous solution (A) remaining was now tested for urea, in the following manner :— (a.) On the addition of a solution of mercuric nitrate to a portion of the above solution, no white precipitate was obtained. (b.) To another portion of the solution (A), a solution of sodium hypochlorite was added. No bubbles of nitrogen were dis- engaged. ss | (c.) No crystals of urea nitrate were formed in a small quantity of the solution (A) [concentrated by evaporation] after the addition of nitric acid. (d.) The distillation of a small quantity of the solution (A) with pure sodium, carbonate, in a chemically clean Wurtz’s flask attached to a small Liebig’s condenser, failed to produce in the distillate any coloration with Nessler’s reagent. 1888.] On the Physiology of the Invertebrata. 327 The above tests clearly prove the entire absence of urea in the secretion under examination. No guanin or calcium phosphate could be detected in the secretion, although the author has found the latter compound as an ingredient in the renal secretions of the Cephalopoda and the Lamellibranchiata (‘Hdinburgh, Roy. Soc. Proc.,’ vol. 14, p. 280). | From this investigation, the isolation of uric acid proves the renal function of the five pouches of the stomach of the Asteridea. II. The Salivary Glands of Sepia officinalis and Patella vulgata. The author has already made a study of the nephridia and the so-called “livers” in both these forms of the Invertebrata (see the memoirs, loc. cit.). Since then he has studied the chemico- physiological reactions of. the secretion produced by the salivary glands of the cuttle-fish and the limpet, these organisms representing two important orders of the Mollusca. (1.) Sepia officinalis. There are two pairs of salivary glands in Sepva officinalis. The posterior pair, which are the largest, le on either side of the esophagus. The secretion of the posterior glands is poured into the cesophagus, while the secretion of the smaller anterior pair of glands passes directly into the buccal cavity. A quantity of the secretion was extracted by using several freshly killed cuttle-fishes. It was alkaline to test-papers. A portion of the secretion was added to a small quantity of starch, the starch being converted into glucose sugar in 15 minutes. The presence of glucose was proved by the formation of red cuprous oxide by the action of Fehling’s solution. The soluble zymase (ferment) contained in the secretion (which is capable of causing the hydration of starch), was isolated by precipi- tating the secretion with dilute normal phosphoric acid, adding lime- water and then filtering. The precipitate produced was dissolved in distilled water and reprecipitated by alcohol. This precipitate converts starch into glucose sugar. When a drop of the clear secretion is allowed to fall into a beaker containing dilute acetic acid, stringy flakes of mucin are easily obtained. The presence of mucin was confirmed by several well- known tests. ‘ Another portion of the secretion was distilled (with the utmost care) with dilute sulphuric acid, and to the distillate ferric chloride solution was added, which gave a red colour, indicating the presence of sulphocyanates. The inorganic constituent, as far as the author could make out, 328 On the Physiology of the Invertebrata. [June 21, consists only of phosphate of calcium. No calcium carbonate could be detected. There is much in favour of the supposition that the diastatee ferment in these secretions is produced as the result of the action of nerve- fibres (from the inferior buccal ganglion) upon the protoplasm of the epithelium cells of the glands. The author intends to examine various organs in other genera and species of the Decapoda, especially those inhabiting the Japanese : seas. (2.) Patella vulgata. * The two salivary glands of Patella are well-marked and situated anteriorly to the pharynx, lying beneath the pericardium on one side and the renaFand anal papille on the other. They are of a yellowish- brown colour and give off four ducts. The secretion of these glands was examined by the same method applied to the salivary glands of Sepia officinalis, and with similar results. The following table represents the constituents found in the salivary secretions of the two orders of the Mollusca already investigated :— ee ee ee Cephalopoda. | Gasteropoda. | (a.) Pulmogaster- | (4.) Branchio- | A RS OR Ee (a.) Dibranchiata. opoda.* gasteropoda. Soluble _diastatic ELLIE pp Spell present present present Alnein. 5. Lost. ek present =a present Sulphocyanates.... present ? present Calcium phosphate. present ? present Investigations indicate that the salivary glands of the Cephalopoda and Gasteropoda are similar in physiological function to the salivary glands of the Vertebrata. i ; ) | * ‘Edinburgh, Roy. Soe. Proc.,’ vol. 14, p. 236, 4 | 1888.] Muscular Movements in Man and their Evolution. 329 Il. “ Muscular Movements in Man, and their Evolution in the Infant: a Study of Movement in Man, and its Evolution, together with Inferences as to the Properties of Nerve- ceutres and their Modes of Action in expressing Thought.” By Francis WARNER, M.D., F.R.C.P., Physician to the London Hospital and Lecturer on Botany in the London Hospital Medical College. Communicated by Professor J. HUTCHINSON, F.R.S. Received June 12, 1882. (Abstract. ) Movements as signs of brain action have long been studied by the physiologist ; but before proceeding to give an account of the visible evolution of voluntary movement in man, it is necessary to define the different classes of movements seen, indicating the criteria by which the observer may be guided in the examples before him. Movements may be classed according to the parts moving, the time, and the quantity of each movement. These are the only intrinsic attributes of such acts. If the nerve-centres which send stimuli to the muscles are acting in equilibrio, the static outcome is seen in the postures resulting in the body ; hence postures are signs of the ratios of action in the nerve-centres, and indicate their present state or mode of action. Typical postures and movements are described. A variation in the ratios of action in the centres leads to visible movement: Certain postures and movements are found by experience to corre- spond to certain recognised brain states. Movements may occur in combinations and in series ; special combinations and series of move- ments determine the outcome of the action of which they are com- ponent parts. It is shown that the time of action in the various centres thus determines the outcome of the action, and is itself con- trolled by impressions received through the senses. When movements are seen, not controlled by present circumstances, they are probably the result of antecedent or inherited impressions; such are called Spontaneous, ; Section II. Evolution of Movements in Man. The new-born infant presents constant movement in all its parts while it is awake, and this is not controlled by impressions from without. Graphic tracings of such movements are given. This _ spontaneous movement in the infant appears to be of great physio- logical importance, and is here termed ‘‘ microkinesis.” It is argued that the mode of brain action which produces microkinesis is analogous to the action producing spontaneous movements in all young animals, and to the modes of cell-growth which produce circumnutation in 330 Muscular Movements in Man and their Evolution. [June 21, young seedling plants. It is argued that as circumnutation becomes modified by external forces to the modes of movement termed heliotropism, geotropism, é&c., so microkinesis in the infant is replaced by the more complicated modes of brain action as evolution proceeds, The conditions of movement are then described, as seen at succes- sive stages of development of the child, and it is shown that they become less spontaneous, and more under control of stimuli acting upon the child from without, while the phenomena termed memory and imitation are evolved. Section IIT. Properties of Nerve-centres and their Modes of Action. From observations made, descriptions are given of the modes of action and properties of nerve-centres in adult age, such descriptions being given in terms implying visible movements. Impressicnability, imitation, and retentiveness are thus described. Nerve-centres are said to be “free”? when only slightly stimulated. Delayed expression of impressions are seen when the visible outcome is delayed after the stimulus which produced it. Double-action is said to occur when a local effect and a distant one, occur from one impression. Com- pound cerebral action is said to occur, when the study of the visible movements indicates that successive unions of centres are in action, leading to a visible outcome well adapted to the primary stimulus which produced the series. When a slight stimulus leads to a spread- ing area of movements producing considerable force, the phenomenon is termed reinforcement. - From observations made, two hypotheses are put forward. It is suggested that when a well co-ordinated movement follows a slight stimulus, the impression produces temporary unions among the centres, preparing them for the special combinations and series of actions which are seen to follow. Such unions among nerve-centres appear to be formed when a period of cerebral inhibition, produced by a word of command, is seen to be followed by a co-ordinated series of acts. A graphic tracing indicating suspension of microkinesis to the stimulus of sight and sound is given. It is further suggested that the brain action corresponding to thought, is the formation of func-_ tional unions among cells, whose outcome is seen in the movements which express the thought, or its physical representation. Properties similar to those described in brain centres may be illustrated in modes of growth. Intelligence is then not a property of the brain, per se, but for its manifestation certain modes of brain action are necessary. In the special postures and movements described, a number of physical signs of brain states are offered to the clinical observer. ; Z 3 1888.] Beat of the Mammalian Heart. Plasticity of Ice. 331 Il. “On the Electromotive Changes connected with the Beat of the Mammalian Heart, and of the Human Heart in parti- cular.” By Aucustus D. Water, M.D. Communicated by Professor BURDON SANDERSON, F'.R.S. Received June 12, 1888. (Abstract. ) 1. Description of experiments in which the electrical variation con- nected with the spontaneous beat is modified. 2. The normal ventricular variation is diphasic, and usually in- dicates (1) negativity of apex, (2) negativity of base. 3. Description of ‘‘irregular” variations. 4. Observations on fae with one or both leading off electrodes applied to ‘he body at a distance from the heart. 5. Determination of the electrical variations of the heart on man. 6. The variation is diphasic, and oe (1) caer tay of apex, (2) negativity of base. 7. Distribution of cardiac potential i in man and animals. “ Favour- able ” and “ unfavourable’’ combinations. 8. Demonstration of electrical effects by leading off frofd the sur- face of the intact body by the various extremities and natural orifices. . 7 9. Comparison between effects observed on man with the normal and with a transposed situation of the viscera. IV. “Qn the Plasticity* of Glacier and other Ice.” By JAMES C. McConneL, M.A., Fellow of Clare College, Cambridge, and Duptey A. Kipp. Communicated by R. T. GuazE- BROOK, F.R.S. Received June 11, 1888. The experiments described in the following paper were undertaken in continuation of those made by Dr. Main in the winter 1886-87, and described by him in a paperf read before the Royal Society the following summer. The investigation is by no means complete, but the results hitherto obtained seem to us sufficiently novel and important to be worthy of being put on record, while we hope to _ * Dr. Main used the term “viscosity.” But this has been always applied in liquids to molecular friction, and we have the authority of Sir Wm. Thomson (‘ Encycl. Britann.,’ Art. : Bkastnaity, p. 7) for reserving it for the same property in solids also, leaving “ plasticity” to denote continuous yielding under stress. t ‘Roy. Soc. Proc.,’ vol. 42, p. 329. VOL. XLIV. 2c H ; ti i i 4: i t 332 Messrs. J. C. McConnel and D. A. Kidd. [June 21, prosecute the subject further next winter. We shall first give a general account of our results, and then describe the experiments in more full detail. Main found that a bar of ice, which had been formed in a mould,* yielded slowly but continuously to tension, though kept at a tempera- ture some degrees below freezing point. We began work under the impression that the rate of extension depended mainly on the tem- perature and tension, and that the chief difficulty lay in keeping the temperature constant. But by a happy chance our very first experi- ment showed us that not merely the rate, but even the very existence of the extension depended on the structure of the ice. And this is a matter which seems to have been quite disregarded by previous experimenters.f After many, and for the most part unsuccessful, attempts to obtain a piece of perfectly clear ice, frozen in the mould used by Main, we took a bar cut from the clear ice formed on the surface of a bath of water, and froze its ends on to blocks of ice fitting the two conical collars through which the tension is applied. To avoid any question as to the ice giving way in the collars, where it is subjected to pressure as well as tension—the bar was pierced near either end by a steel needle firmly frozen in, and the measurements were taken between the projecting ends of these needles. We found to our astonishment that the stretching was almost nl, though the tension was decidedly greater than that usually applied by Main. There was a slight extension at first, but during the last five days the extension - observed was at the mean rate of only 0:00031 mm. per hour per length of 10 cm., and this may well be attributed to the rise of temperature which took place. The rigidity cannot have been due to the cold, for during the last 24 hours the temperature was between —1° and —2°.{ After the experiment, the ice was ex- amined under, the polariscope, and found to be a single regular crystal showing the coloured rings and black cross very well. The optic axis was at right angles to the length of the bar. This experiment showed it was a very necessary precaution to take the measurements between needles fixed in the bar itself. For whether the bar extended or not, the movement of the index H (fig. 2), showed * The mould produced a round bar of ice 24 cm. in length and 2°8 cm. in diameter, with a conical expansion at the lower end to fit into an iron collar C (fig. 2), through which the tension could be applied. The other end of the bar was frozen on to ice filling a similar collar B. These iron collars were faced with carefully worked brass plates, and Main determined the extension by measuring the distance between the plates with callipers.—July 6, 1888. + See Heim, ‘ Handbuch der Gletscherkunde,’ published by Engelhorn, Stuttgart, 1885, p. 315. ; { We use the centigrade scale of temperature throughout. 1888.] On the Plasticity of Glacier and other Ice. 333 a decided separation of the collars due to the plasticity of the conical pieces of ice therein. We next took a bar of ice formed in the mould, applied tension and took measurements in the same way. The extension was at the rate of 0:048 mm. per hour per length of 10 cm. The crystalline structure of this ice was highly irregular. As one principal object of our ex- periments lay in their application to the theory of glaciers, it had now become obviously most important to test actual glacier ice. We therefore drove over to the Morteratsch glacier, which is now readily accessible from St. Moritz even in the winter, and obtained some specimens from the natural ice caves at the foot of the glacier. We tested three pieces, which were quite sufficient to disprove the common notions, that glacier ice is only plastic under pressure, not under tension, and that regelation is an essential part of the process. They showed at the same time the extraordinary variability of the phenomenon. The first extended at a rate of from 0°013 mm. to 0:022 mm. per hour per length of 10 cm., the variations in speed being attributable to temperature. The second piece began at a rate of 0-016 mm. and gradually slowed down till it reached at the same temperature a rate of 0°0029 mm., at which point it remained - tolerably constant, except for temperature variations, till a greater tension was applied. The third piece on the contrary began at the rate of 0'012 mm., increased its speed with greater tension to 0'026 mm., and stretched faster and faster with unaltered tension, till it reached the extraordinary speed of 1°88 mm. per hour per length of 10 em. We put on acheck by reducing the tension slightly, whereupon the speed fell at once to 0°35 mm. and gradually declined to 0:043 mm. The lowest temperature reached during our experiments, except with the intractable bath ice, was with this specimen. During 12 hours with a maximum temperature —9° and a mean temperature probably —10°5°, the rate under the light tension of 1°45 kilo. per sq. cm. was 0:0065 mm. These three pieces were composed of a number of crystals varying in thickness from two or three millimetres up to thirty or evena hundred. These crystals are the ‘glacier grains” (gletscherkérner), which play such a large part in glacier literature. Glacier ice is a sort of conglomerate of these grains, differing, however, from a conglomerate proper in that there is no matrix, the grains fitting each other perfectly. In the winter, at any rate, the ice on the sides of the glacier caves looks quite homogeneous. But, when a piece is broken off and exposed to the sun’s rays, the different grains become visible to the naked eye, being separated probably by thin films of water. Though the optical structure of each grain is found under _ the polariscope to be perfectly uniform, the bounding surfaces are utterly irregular, and are generally curved. The optic axes too of 2 G2 -_ o£ St J ‘eat ae Se ———_ ED a nr, eS Sp Sess sso see hl ee 334 Messrs. J. C. McConnel and D. A. Kidd. [June 21, neighbouring grains seem to be arranged quite at random. Owing to the structure being so complex, we failed to trace any relation between the arrangement of the crystals and the rapidity of extension. It is true that the most rigid piece of the three was composed of small crystals, while the most plastic contained one very large crystal ; but this was perhaps accidental. Fortunately, we were able to obtain ice of a more regular structure, which has already thrown a little light on the action at the interfaces of the crystals, and offers an attractive field to further investigation. Some of the ice of the St. Moritz lake is built up of vertical columns,* from a centimetre downwards in diameter, and in length equal to the thickness of the clear ice, 1.e., a foot or more. A hori- zontal section, exposed to the sun for a few minutes, shows the irregular mosaic pattern of the divisions between the columns. The thickness of each column is not perfectly uniform. Sometimes indeed one thins out to a sharp point at the lower end. Hach column is a single crystal, and the optic axes are generally nearly horizontal. Some experiments on freezing water in a bath, lead us to attribute this curious structure to the first layer of ice having been formed rapidly, in air, for instance, below —6°C. We found that if the first layer had been formed slowly, and was therefore homogeneous with the axis vertical, a very cold night would only increase the thickness of the ice, while maintaining its regularity. We applied tension to a bar of lake ice carefully cut parallel to the columns. It stretched indeed, but excessively slowly. During seven days it stretched at the rate of only 0:0004 mm. per hour per length of 10 cm., though at one time the temperature of the surrounding air went up above zero. The tension was 2 kilos. per sq.cm. This slight extension may well be attributed to the tension not being exactly parallel to the interfaces of the columns. This experiment corroborates our first result, that a single crystal will not stretch at right angles to its optic axis. We next cut a bar at about 45° to the length of the columns, and the difference was very manifest. During 80 hours under a tension of 2°75 kilos. per sq. cm., it extended at the rate of 0015 mm. per hour per length of 10 cm., nearly 40 times as fast. | An icicle is an example of ice formed of very minute crystals irregularly arranged. We found that an icicle under a tension of 2'2 kilos. per sq. cm. stretched at the rate of 0°003 mm. per hour per length of 10cm. This is very slow, especially as the temperature * This was the case in all pieces obtained from one end of the lake, where men were cutting ice for storage purposes, whether new ice or old. In a part, however, which had frozen a few days earlier, further out from the shore, we found much larger crystals with the axes nearly vertical but not quite parallel to each other.— July 6, 1888. 1888. ] On the Plasticity of Glacier and other Ice. 335 was high, averaging —1°C., yet it is difficult to suggest any theoreti- eal reason for an increase in the number of interfaces producing a decrease in the plasticity. We tried further two experiments on compression of ice, the pressure being applied to three nearly cubical pieces at once. Of three pieces of glacier ice, under a pressure of 3°2 kilos. per sq. cm., the mean rates of contraction during five days were respectively 0-035 mm., 0056 mm., and 0:00/7 mm. per hour per length of 10 cm. These figures show that while the plasticity varies enormously in different specimens, the rate of distortion is of the same order of mag- nitude, whether the force applied be a pull or a thrust. The other experiment was on three pieces of lake ice, apnlying the pressure in a direction parallel to the columns. The contraction was scarcely perceptible. Under a pressure of 3:7 kilos. per sq. cm., the mean rate of the three pieces during four days was 0:001 mm. per hour per length of 10 cm. To fix the blocks of ice in position, we found it necessary to cover their ends with paper frozen on, and the small con- traction observed may well be attributed to the yielding of the films of irregular ice with which the paper was attached. This view is supported by the fact that nearly the whole of the contraction took place in the first 36 hours. We have now shown by direct experiment that ordinary ice, con- sisting of an irregular aggregation of crystals, exhibits plasticity, both under pressure and under tension, at temperatures far below the freezing point—in the case of tension at any rate down to —9° at least, and probably much lower—and also that a single uniform crystal will not yield continuously either to pressure or tension when applied in a direction at right angles to the optic axis. We fully intended to test a crystal under tension applied along the optic axis; but we were unsuccessful in obtaining a crystal longer in the axis than perhaps 8 cm., and when we had decided to be content with that length, a thaw put a stop to all further operations. We have, however, very little doubt that a crystal would refuse to yield either to pressure or to tension in whatever direction they were applied. The following reasoning seems tolerably conclusive as far as it goes. We first assume the axiom that, if two systems of stresses produce each by itself no continuous yielding, superposition of the two will likewise produce no continuous yielding. This will probably be admitted when we add the proviso that, when the nature of the _ resultant stresses is found, their magnitude is to be reduced to the same value as that of the simple stresses which are known to be inactive. Take then a cube of ice, two of whose faces are perpen- dicular to the optic axis. Apply tension to one of the other pairs of faces. This according to our experiments produces no extension. : : 336 Messrs. J. C. McConnel and D. A. Kidd. [June 21, Of course we do not take into account the slight elastic yielding. Apply an equal tension to the other pair of faces which are parallel to the axis. There is still no extension by the axiom. Now it can hardly be supposed that an uniform hydrostatic pressure could pro- duce continuous change of form. Apply then a pressure of such magnitude as to neutralise the two tensions. We have then remain- ing only a pressure along the optic axis, producing no continuous yielding. “In asimilar way it may be shown that tension along the optic axis would produce no continuous yielding. It is true that the reasoning cannot be extended to pressures and tensions oblique to the optic axis. But if the plasticity observed had been due to the majority of crystals extending, while a certain number remained unchanged, there would surely have been numerous cracks found in every case; while as a matter of fact such cracks were only found in two cases, and then they were very slight. Hence, while we think it desirable to experi- ment further in the matter, we feel tolerably confident that single crystals of ice are not plastic, and we attribute the apparent plasticity of glacier ice to some action at the interfaces of the crystals. But we are not at present inclined to venture any opinion as to the nature of this action. The variation of plasticity with the temperature is of great intere st both for the theory of glaciers and for the explanation of the plasticity itself, but it is so difficult to disentangle the temperature variations proper from the much larger alterations due to structural changes, that our experiments throw very little light on this point. In the case of the glacier ice in Experiment 7 the rate seems to have become tolerably constant except for temperature changes. While at —3°5° the rate was 0:0029, two days before and two days afterwards it was about 0°0020 at —5°, and a few days earlier 0:0013 at —8°. In the icicle, when the temperature variations seemed paramount, the rate at —2° was 0°0028, and at —0-2° 0:0034. This is a much smaller change than we should have expected. In the case of compression the influ- ence of temperature seems more strongly marked. Im all three pieces the rate rose at —3° to about ten times its value at —5°. An increase which takes place in three pieces simultaneously can hardly be attributed to structural changes independent of the temperature. The change in the rate of extension, produced by an alteration of the tension, was in every case altogether out of proportion to the magnitude of the latter. In the following table are collected all the instances which occurred :— 1888. ] On the Plasticity of Glacier and other Ice. 337 Specimen. Change of tension. Change of rate. kg. per sq.cm. | mm. per hour per10cm. Glacier ice C...... 2°55 to 3°85 0°0018 to 0:0110 Glacier ice D...... 145 |, 2°55 0°0075 ,, 0:026 4: ee lies sen AOS 0-105? ,, 0-010 ia Pe colt we ahi Ose ay eo) 0-010 ,, 0°228 ‘ eo Magy & tee 1:88 ,, 0°35 The changes of temperature in these cases were insignificant com- pared with the alteration of rate. The 0°105 is uncertain owing to an accident. It was certainly not less, and may have been a good deal greater. We append a summary of some of our results arranged in tabular form. Glacier ice C was the same piece as B, cut rather shorter. [June 21, Messrs. J. C. McConnel and D. A. Kidd. 338 “ “ “ S100: O | (9 POCO bila (7 ‘ 46 «< - ZT00-0 mn rresresescess oF 4 suUInpoo 09 JoT[RIed ‘or exer] rh 0-9 — 6. ¢— Le Z000- 0 | BARR. Spates one oe Z “ ‘“ cc 100-0 6¢ iP EE eae een See oe ae gS ede ee Suances 9 yc NG) ODES) (79 “ “ “ 960. 0 | “ Pa ppsyak UR WaTe ths Sis eola ne + aus 0 * TS OTOUNG oT 0-9 =: 8.2- Ze ceo. 0 sfep g Bree verte le the. aca ine eee pe ess Seater OO. JOLemI) T | "SO]TY oInssorg ‘sqyuoultiodxq@ uorsserduroy) 0-9 — ¥ St O10-0 “ OL |°° 998d TanmTUIUL $f gg — 9.9- G1. E0- 0 smoy 9 | + oyex umentxear f STMT? OF EMPITAO ‘oor OME] Ot G.G a 0-F— 8.Z% 9/000- 0 (79 Zz eoeveeeee re eos cree ess “OTSA 104BaId 66 (14 G.g — 0-0 5 2 62000: 0 - skep J reeeeeceseseee se sumNoo 09 [oT[ered ‘or oye 6 bet =~ L-0- G3 CT00- 0 6c g SSE Veh viene ae ne. 2 e's OneT CMM TULL TG tc 0-0 0.0 ZG TF00-0 (79 G eo ere ee ee ee oe ese oe te oe ee oye TINWIXBUL ‘aTOTOT 9 Q. OL = 0. 6- 74 6900-0 ce rat ee ere reve ens oinyeradure4y qSaMO] ' 66 (79 0-0IL- 0.9-— Gr. T PSO0- O sInoy OL eo ere ee een ee ee on *-94Ba TUNUTUT OL (3 (13 LZ T-Z2- 0S-2 88.1 ‘SUITE OT [oc tt eqer UnTaIxem ‘qf 9dT JOIOBTDH g 0-6 — 0.9— 6c ©100- 0 sfep ¢ OD CCRC STIS aH TUN UTU TO 9 66 CG.P = G.Z— GG.Z 8900-0 (19 °% ee reer ee ee ee ee oe (9 ve) 901 LOTOBT) Va Cag = g.o—- iG 9T0- O pe jeer sts: eyed UNMIXBUL “Eg 901 TOTORT) ¢ G.Z a 0-I- ce £T0-0 (73 P ceovrre vr ee ee eee o4ea LOtaaueradeqaony 74 (9 0.2 _— 0-0 99.T 260-0 ce G osc eopeer ener ee ee *OqBl UINUIXeUl ‘Vv 901 TOTO - 40-G os 0-0 8. SFO. O sinoy gz atige GE SOR PANS RS rae es eee eer Onan) | TLONAT g ss A s 00000-0 ¥ rereeeoe ss -ommgvioduiey OF poqoort0o A se ooh 0-1- 6. F 8z000: 0 skep ce vreeeees omngvrodutey LOZ poyooritooun ‘vor Weg Z eae "U1 OT ; pa ed pero tesodunag ae aed jo Wysue] sod ‘uur ur} ‘uoeindg ‘ueuitoeds Jo uoTydi10s0q ON -1190] UBIO | UMUIXVy, | ‘SOTIY UoTsueT, quourmed xy amoy tod 04% ‘syueultodxg uoisueyxq + ‘Areuruing 1888.] On the Plasticity of Glacier and other Ice, 339 lt will be interesting to make some numerical comparison between the figures we have given and the plasticity actually observed in the motion of glaciers. Perhaps the most striking proof of the existence of plasticity is the great increase of velocity from the side to the centre of a glacier. A number of measurements on this point have been collected by Heim (‘ Gletscherkunde,’ p. 147). The most rapid increase he mentions among the glaciers of the Alps is on the Rhone glacier, on a line 2300 metres above the top of the icefall. At 100 metres from the western bank the mean yearly motion, 1874 to 1880, was 12°9 metres; at 160 metres from the bank it was 43°25 metres. This gives an increase of velocity in each metre across the glacier of 0000058 metre per hour. Let us consider what rate of extension this involves. Pret. Let AB (fig. 1) be two points on a glacier moving in parallel direc- tions, of which B is moving faster. In the small time é¢ (whose square we may neglect) let A move to A’and Bto B’. Draw AN, A'N’ perpendicular to B’B produced. Let AN = A’N’ =a, BN =a, B'N' =2#', AB =7, A’B' =7’, and let the velocities be vq and %. Then A‘'A = 1% 6, BIB = » ét, r = af+22, r2= +a? = a®+{at+ (v—v.)ét}? = a®+az?+2zx (vi—va) St 22(v5—Va) dt eves rts So” 7 ’ (1+ Baa } 340 Messrs. J. C. McConnel and D. A. Kidd. [June 21, ! 4 —Va 6 and eo r(i+% oe a? +a? r—7 ay 4 "i } sO ee Or ee (v4) Ot. EPS ee eee The expression — #8 = 1S a maximum when x = a, and then we have a+ 2x? by (1)— le’ —r %—Va a ét eA Da : . . . . ° : . . (2.) When ¢é¢ is very small, the ratio of 7’—r to ét is the rate of increase of the distance between A and B. So, if we take any two points of the glacier at unit distance, the rate of increase of the distance between them will be greatest when the line joining them is at 45° to the direction of motion, and this maximum value will be equal to one half the difference of the velocities of two points situated abreast of each other and also at unit distance. Thus the maximum rate of extension in the case we have taken on the Rhone glacier is 0°0029 mm. per hour per length of 10 cm. This, be it remembered, is the most rapid extension selected from a large number of measurements on different glaciers and at different times, and yet only one of the three specimens of glacier ice showed a rate less than this, and that was under one-third of the breaking tension. The larger the specimen, the greater average plasticity would it dis- play ; for the addition of a small piece like our second specimen, for instance, would suffice to make a long rigid bar appear very plastic. Hence the glacier itself would be far more plastic than most small specimens taken at random from its mass. It would seem, therefore, that neither the presence of crevasses nor a thawing temperature are essential conditions of the motion of a glacier. But that crevasses are found is not surprising, when we consider the rotten state of the ice during the summer and the certainty that a crack, however small, once formed will continue as long as the tension exists. We believe further that the stresses produced in a glacier by its own weight are comparable with those employed in our experiments. Description of Apparatus. We had two sets of apparatus in operation. ‘The first was that employed by Dr. Main, figured and fully described in his paper. We reproduce his figure unaltered, though we made a few alterations in the surrounding boxes, As we expected at first that our chief difficulty would be keeping the temperature constant, we made special arrangements for overcoming this. To secure a large heat capacity we 1888. | On the Plasticity of Glacier and other Ice. 341 introduced two tins, filled witha strong solution of salt, into the inner box, slightly altering its shape and increasing its size for this purpose. A broad shallow tin occupied the spare space at the top, and a tall tin occupied all the available space by the side of the ice between A and Li (fig. 2). The space between the two boxes was filled with A GG Pl | S = . Be —— Fie. 2 N il WN \ WN \< eee eum UIQ IINIMiG 342 Messrs. J. C. McConnel and D. A. Kidd. [June 21, wood shavings, except between K and M. Here a wooden partition P was inserted to the left of the vertical connecting rod. The space between K and P was filled with wood shavings. To allow the lever to move freely, it passed through a wooden tube loosely packed with cotton-wool. The outer space between P and M was made fairly air-tight, and the opening through which the lower lever emerged was also plugged with cotton-wool. The capacity of the inner chamber was about 60 litres, while the two tins contained about 25 litres of solution. The inner chamber was thus jacketed on all sides with a layer, from 104 to 20 cm. in thickness, of which from 4 to 6 cm. was solid wood and the rest wood shavings. To secure uniformity* of temperature the back of. the inner chamber was lined with thick sheet-copper. Originally the front was similarly provided, a small aperture being cut for the cathetometer readings. But after the first experiment this was found very Inconvenient and was discarded. Access to the box was obtained from the front, the space between the doors of the two boxes being filled with a movable pad stuffed with shavings. The inner door occupied about half the front of the ice-chamber. With these arrangements the temperature of the interior altered very slowly, often not more than a degreee in 24 hours, though no special precautions were taken to keep the temperature of the room constant. We were not so successful in maintaining uniformity of temperature. The minimum thermometer was hung at the back of the chamber on a level with the middle of the ice, The maximum was placed with its bulb at the bottom of the chamber at the end removed from the tin, And we often found that the temperature at the time, shown by the maximum thermometer, was one or one and a half degrees lower than that shown by the minimum. In the temperatures given in the tables allowance is made for this. We found, however, that the variations in the plasticity due to the temperature were far exceeded. by others, due probably to changes in the crystalline structure of the ice. In explanation of the considerable variation of temperature occasionally recorded in the tables, we must add that, in order to raise or lower the temperature, the inner chamber was sometimes left wholly or partially open. The front of the box was close by an open window, and was generally exposed to a decidedly lower temperature than the back, so that opening the doors to take the readings would seldom raise the internal temperature materially. The bar of ice for an experiment was roughly sawn out and then shaped more carefully with a knife. A hole was bored near each end with a hot steel knitting needle. This was found to be the only method of making a hole free from the risk of splitting the ice. In each hole was frozen a short piece of steel knitting needle with the * Uniformity refers to space, constancy to time. — :1888.] On the Plasticity of Glacier and other Ice. 343 ends projecting slightly. In the later experiments we used pieces of glass tube or rod for needles, to obviate any possible exaggeration of the extension through the needle bending in the ice. The glass had the further advantage of being a bad conductor of heat. We found that, when air above freezing point entered the chamber during the taking of a reading, the steel needles were apt to work loose, although the body of the ice had not time to materially rise in temperature. Such readings are of course discarded. The two conical collars were filled with ice by freezing water therein. The upper collar was taken out and inverted, and its brass plate levelled. Then the bar was carefully placed in a vertical position and frozen on. The bar was next hung in position in the chamber and frozen on to the ice on the lower collar in situ. In the first experiment the measurement of the distance between the upper and lower needles was made with a cathetometer. On the two ends of each needle were glued pieces of paper, on each of which fine ink cross lines had been drawn. The cathetometer was not of the ordinary construction and merits a short description, as, though in practice it was not very successful, in principle it has, we believe, several advantages over the ordinary form. The stand consists of a vertical rod supported by three levelling screws. On this rod slides a metal block, provided with a clamp and slow-motion screw. The telescope rests on this block, being movable through ninety degrees about a vertical axis. The bearing of the telescope is the only mechanical part of the instrument that requires special care. For the cross wires of the ordinary telescope is substituted a micro- meter scale. The millimetre scale is fixed on a separate stand as near as possible to the bar of iceand at the same distance from the telescope as the ice is, and is left untouched during the observations, so that it is of no consequence, for measuring small extensions, if it be not quite parallel to the direction of the tension. The distance from the telescope to the ice or to the scale was about 30 cm. On the top of the telescope is fixed a level. We carefully adjusted this, so that when the bubble was at its zero the axis of rotation of the telescope was in the vertical plane at right angles to the tube of spirit. Then if the bubble remained in its central position in every azimuth of the telescope, we could be sure the axis of rotation was vertical. The observation was taken by reading the position, on the micro- meter scale, of the image of the mark on the needle, then swinging the telescope round and reading the position, on the micrometer scale, of the two nearest divisions of the millimetre scale. By interpolation the exact height, on the millimetre scale, of the mark on the needle was then readily found. It willbe noticed that the cathetometer need only remain steady while the telescope is swung round from the needle to the scale; whereas in the ordinary form there is a danger 344 Messrs. J. C. McConnel and D. A. Kidd. [June 21, of the whole stand being slightly displaced when the telescope is slid down to its lower position. In fact in our circumstances an ordinary cathetometer would have been practically useless, owing to the bending of the floor and table at the slightest movement of the observer. Observations, even with our special form, required the utmost care. The micrometer scale had twenty divisions, each 0:12 mm. in actual size, and corresponding to about 0°3 mm. on the other scale. The magnification of the telescope, as compared with the eye at 9 inches, was about 5. This was scarcely great enough. We intended also to have the micrometer divisions half the size, but the maker was not able to graduate it so finely. Indeed, as it was, the lines were rather too thick. By estimating tenths of the micrometer divisions we could read to 0:03 mm., but the readings might easily be at least 0°06 mm. in error. Each determination of the length between the needles depends on four readings, the upper needle, and its corresponding scale division, and the lower needle, and its scale division. If the four readings happened - to have each the maximum error 0°06 mm. with a suitable sign, the total error might be 0°24 mm. Such a combination of chances is highly improbable, but an error of 0°1 mm. is obviously not unlikely. The cathetometer would have been a useful instrument for measuring a large and regular extension with accuracy, butit was not adapted to detect very small extensions, and a system of levers, which we adopted as a rough mode of measurement in our second set of apparatus, proved iso much more satisfactory and suitable to our purposes, that we almost entirely discarded the cathetometer. This contrivance is shown in fig. 3, in the form finally adopted. a and b are sections of the projecting ends of glass needles fixed in the ice, cdef is a bent iron wire, “the indicator,” hooked to a wire loop m securely fastened to a, h is a wooden lever suspended by a thread n, which owing to the counterpoise k, pulls the indicator upwards with a thread fastened to awire loop at e. The indicator is kept from rising by the connecting fibre, a piece of stiff wire hooked at one end to the loop g, fastened to b, and at the other to a bend d* in the indicator. The lower end of the indicator gives the reading on a paper millimetre scale J, gummed on to the mirrory. The mirror, of course, enables the observer to avoid errors of parallax. The stand of the mirroris glued to the lower collar. To appreciate the action of the levers, regard a for the moment as fixed, then lowering 6 through a small distance r will move f through a distance s = vr at right angles to mf, where v is the ratio of the distance mf to the perpendicular let fall from m on the line gd produced if necessary. If md be made perpendicular to gd, when f is in the middle of the scale, the multiplier » remains practically constant. This precaution was not always taken, but * This was a deeper bend than is shown in the figure. 1588. | On the Plasticity of Glacier and other Ice. 345 Fie. 3. allowance is made for the resulting error. Two lever systems were required, one for the outer ends, and the other for the inner ends of the needles passing through the ice. In Experiment 2 we used two scales and mirrors which enabled the readings to be taken with great accuracy. Afterwards we contented ourselves with one, which gave quite sufficient accuracy for any but homogeneous ice. In the first few experiments we used glass fibres, both for the indicator and connecting fibre, as we feared some slight motion of f might arise from the “elastic recovery’ of the wire. This was put to the test of experiment. A long piece of the same kind of wire was bent sharply at an angle, and the two ends brought nearly into contact. It was hung over a nail, and the distance between the ends measured from time totime. The effect of the gradual unbending of the angle would 346 Messrs. J. C. McConnel and D. A. Kidd. [June 21, in this case, owing to the greater length of the arms, be about twice as great as in the extension experiments, and yet it was found to be scarcely perceptible. For practical convenience in setting up the apparatus the wire was found immensely superior. The trouble of fixing in position a delicate arrangement of brittle glass fibres, in an awkward place like the back of the ice chamber behind the bar of ice, can hardly be realised by any one who has not tried it. In the first few experiments the loops m and g were not used, and the indicator and connecting fibres were simply hooked over the needles a and b. And in Experiments 2, 3, 4, and 6, no efficient precautions were taken to prevent slipping aloug the needle. It is to be remarked, however, that any such slipping would produce an apparent contraction, and, owing to the sudden alteration of the rate of extension, any slipping of importance could hardly escape detection.* Such cases are either omitted or specially mentioned. The lever h and counterpoise were found rather troublesome, and will probably be dispensed with next year, by putting the connecting fibre on the other side of the needle. | Our second apparatus, which we shall call the rough apparatus, was of much simpler construction. Instead of the collars we used two iron plates, each about 12 cm. square with a hole 2’5 cm. squarein the centre. The bar to be tested was passed through the hole and frozen on to a block of ice on the other side of the plate. The upper plate was suspended by cords attached to holes at the corners, and from the lower plate was suspended by similar cords a bucket, in which various weights could be placed. In Hxperiments 3 and 4, the four cords were simply knotted together, and hung over an iron hook fastened to a single cord. But it was difficult in this way to ensure that the line of action of the tension should be the central line of the bar of ice, and we thought it likely that the bending in Experiment 4 was due to this cause, so we adopted the contrivance shown in fig. 4. A is the upper iron plate, F the bar of ice attached to the block of ice E.t Bisa wooden plate with holes at the corners and a hole at the centre, in exactly the same relative positions as the holes in the corners and the centre of the square hole in A. CCCCare four cords of equal length, and D the main cord by which the whole is upheld. When the arrangement is in equilibrium, the cords C will be vertical as well as the cord D, so the line of action of the tension, which is the central line of the cord D, will pass through the centre of the square hole in A, even though the two plates be not quite horizontal. The same remarks apply to a similar arrangement for the lower iron plate. If * In almost every experiment far more readings were taken than are recorded ~ below. + This block was thicker than in the figure. 1888. | On the Plasticity of Glacier and other Ice. 347 the bar be not attached accurately at right angles to the plates, it will take up a vertical position and the plates will be tilted. This contrivance was successtul, for the icicle, which owing to its symme- trical formation would probably under uniform tension stretch equally on both sides, showed but small signs of.bending. So we think it fair to conclude that in the later specimens the bending was due to their unsymmetrical structure. In the later experiments (6, 8,9 and 10) the apparatus was en- closed in a single box of wood about 3 cm. thick. The box was jacketed on the outside with a layer of hay about 5 cm. thick, covered with paper or felt, The cords, leading to the support and the weight, passed through holes in the top and bottom well plugged with cotton-wool. In all cases, except when the contrary is expressly mentioned, the bar of ice was wrapped in gutta-percha tissue to check the evaporation. The polariscope was of the simplest possible form. The light _ transmitted by a sheet of thin paper was reflected at the polarising angle by a pile of three glass plates towards a Nicol prism supported in the same framework. With its aid it was easy to see the boundaries of the various crystals in a plate or bar of glacier ice, though not a trace of division could be detected with the naked eye, and with some difficulty the direction of the optic axes of a few of the larger crystals could be made out. In the bath ice the homo- geneousness of the crystal could be readily tested, by watching the unchanged position of the rings and cross while the bar was moved across the field. In lake ice a half-inch plate, cut at right angles to the columns and viewed in the polariscope, showed a series of irregular polygons black, white, or grey, when the empty field was black. The almost invariable absence of colour proved that few or none of the VOL. XLIy. 2D 348 Messrs. J. C. McConnel and D. A. Kidd. [June 21, optic axes were nearly parallel to the length of the columns. That the axes, however, were not accurately perpendicular to the length of the columns, 7.e., horizontal in the original position on the lake, was shown by examining separate columns. After allowing the ice to thaw slightly, or better after leaving it in the rays of the sun for twenty minutes, the columns could be easily separated. Detailed Account of the Hxperiments. It will be more convenient to describe all the experiments made with Main’s apparatus first, than to keep to the chronological order. Experiment No.1. Main’s Apparatus.—Measurements were taken with the cathetometer. The specimen was a square bar of ice, taken from the surface of a bath of water about a foot deep, and cut into shape with a knife. It was perfectly clear and free from bubbles. It was wrapped in gutta-percha tissue, which was not removed till the end of the next experiment. The “needles” were pieces of steel knitting needle. The area of the section was 8°l1 sq. cm., and the tension 3°7 kilos. per sq. cm. Difference between the Distance Tormeme two sides. Date. between Extension. t Pp ure. needles. Upper. Lower. mm. mm mm mm Fone 14; a he ohh 6S 98 0-0 —370" Al 4-6 seed Gh Ohh 164-06 +0°13 —8-0 45 43 oedey pere 163 ‘91 —0 02 —7-0 4°3 4-2 SPiloks |<) cael 16404. +0°11 —6°2 4°3 4-2 NAO DY eas 163-98 +0:05 —5°5 4:3 4:2 iy eat He 16408 +0°15 —5:0 , oe ae 164-01 +0°08 }: 507) ie al Me ees aan te fe +0:20 —4°0 4:4 41 The hours in the first column are reckoned from midnight. The third column gives the extension observed, measured from the length at the first reading. The fourth column gives the temperature just before each reading. The maximum temperature during the whole period was —3:0° and the minimum —8'5°. The fifth column gives roughly the difference between the heights of the marks on the right and left ends of the upper needle, and the sixth column the same thing for the lower needle. These are added to show that a slight bending took place chiefly between the 14th and 16th. On removing the gutta-percha, at the end of the next experiment, a surface crack was found which may have occurred at the same time. Hach reading 1888.] On the Plasticity of Glacier and other Ice. 349 on the micrometer scale of the cathetometer was taken twice, the telescope having been turned about the vertical axis in the interim. The two generally agreed. If not the mean was taken. On the 20th, however, a second set of readings was taken, the telescope having been slid down the rod in the interim. Both determinations are given. The errors of a cathetometer reading have been already discussed. If we allow 0-11 mm. as a possible error in each determination of the length, the observations are consistent with no real extension. But taking the last two columns into consideration it seems probable that there was an extension of 0:1 mm. between the 14th and 16th and none later. Hvenif the total extension had been 0°2 mm., this would have corresponded to a mean extension per hour per length of 10 cm. of only 0:0007 mm. Haperiment No. 2.—The same piece of ice was fitted up with glass indicators and glass connecting fibres, the needles being the same as before. Hach indicator was provided with a mirror and scale set close up to it, so readings on the scale could be taken to 0°2 mm. But on the other hand there was a possibility of the indicators slipping on the needles and thus occasioning a slight apparent con- traction. The multiplication on the outer side was 34, on the inner 26. Thus an extension of (:007 mm. could be detected. The second, third, and fourth columns of the following table give the extensions, measured from the length at the time of the third observation (for a reason mentioned below), and reduced to the pro- portionate amount for a length of 10cm. They are probably correct to — 0:004 mm. Experiment No. 2.—Main’s Apparatus. Bath Tee. Length between Needles 16 cm. Tension 4°9 kilos. per square centimetre. Extension per 10 cm. Date: Temperature at the time. Outer. Inner. Mean. eee eee | eae een eee eet See a eee mm. | mm mm Jan. 30, 10 h. 30 m 0°016 0-000 0-008 — 5:0° ae 16h. 30m 0°016 0°055 0-035 pee, oO tte 15. m 0-000 0-000 0-000 —15:0 UO —0°002 0-000 —0-001 —12°5 Feb. 1, 9h. 30m 0-000 0:019 0-009 8°5 TN ae —0 002 0-002 0-000 248 18 mo LO... 0 :007 0-022 0°014 — 6°4 fos, Oh. 45 m 0 :007 0 °022 0-014 — 6°5 Ps 72 7 a 0-009 0°045 0°027 — 3°7 tS hy 10.m 0-007 0°050 0°028 — 1°6 wee, Oh. 30m 0 °0U7 0°048 0 027 — 1°5 SS 0-007 0°048 0°027 — 1°0 A i ee 30 Messrs. J. C. McConnel and D. A. Kidd. [June 21, The temperature on the afternoon of the 30th was not taken, but the notebook contains a statement that it was colder than the morning. Since the box was left open all night, the temperature given by the thermometer on the morning of the 3lst may well have been rather lower than that of the ice. Between the Ist and 2nd, an apparent contraction of 0°017 mm. on one side took place without change of temperature. This looks as if the indicator had slipped. Making allowance for these, the mean extension from the 31st, 9h. 15 m., to the 5th, 16h., follows the temperature very fairly, considering the uncer- tainty of the latter. We have arranged the table to show this. But during the first six hours there was an expansion on one side of 0-088 mm. in actual magnitude, which we attribute to a slight yield- ing at the crack. Counting the contraction as a slip, and making no allowance for temperature, the mean rate during the whole 150 hours was 0°00019 mm. per hour per length of 10 cm. If we suppose that the extension during the last five days was entirely due to temperature, and that the coefficient of expansion of the glass of the connecting fibre was 0°:000009, we have between —12°5° and —8‘5° a coefficient of linear expansion of ice of 0:000034, between —8°5° and —3°7° of 0:000060, and between —3°7° and —1-0° of 0:000009. Into the complicated question of the expansion of ice with tem- perature we do not care to enter fully. We will merely cite two investigations. The best observations on the cubical coefficient seem to be those of Pettersson (‘‘On the Properties of Water and Ice,” ‘Vega Expedition,’ vol. 2, Stockholm, 1883). We deduce from his figures the corresponding linear coefficients, supposing ice to be isotropic in this matter. With ice from ordinary distilled water he obtained 0°000053 between —12° and —2°. This ice began to con- tract at some point between —0°35° and —0°25°. With ice from the purest water he could obtain, the coefficient rose from 0000055 between —17° and —10° to 0:000057 between —4° and —8°, and then decreased, till it changed sign at some point between —0°15° and —0:03°. Ice containing 0°014 per cent. of chlorine, in the shape of salts, began to contract at —2°5°. In these experiments the water was frozen in the dilatometer, so there was no chance of the impuri- ties being expelled by the process of solidification as in the case of ice formed slowly on the surface of some depth of water. His purest water, however, was so good as to be seriously affected by boiling for a short time in a clean glass vessel. The coefficient of linear expansion has been determined directly by Andrews (‘Roy. Soc. Proc.,’ June, 1886). He found 0:0000505 between —18° and —9°, and 0:0000735 between —9° and —0°. It is possible that the difference between the determinations of these two . PA 1888. | On the Plasticity of Glacier and other Ice. 351 experimentalists is owing to an unequal expansion of ice in different directions. At any rate, taken together, they are sufficient to explain our rough results, on the supposition that the extension of the last five days was entirely due to the rise of temperature. The experiment was brought to a close by the bar breaking at a point above the upper needle, where it was not protected by gutta- percha tissue, and had become very thin through evaporation. The thickness had been reduced by this cause in, three weeks from 2°85 em. to 22 cm. The temperature, at which the fracture occurred, was between —0°5° and —1:0°, certainly not above the former. The breaking tension was 8°35 kilos. per sq.cm. There was a groove running right round the bar near the middle of its length, but no sign of a crack could be seen in the interior of the ice. This - groove may have been caused by the outer layer cooling more rapidly than the interior. Under the polariscope no break in the continuity of the crystalline structure could ‘be detected. The rings and cross were seen very plainly, and the direction of the optic axis appeared to be the same on both sides of the crack. It was perpendicular to the length of the bar and also to the needles. By a rough measure of the rings we found the difference between the two indices of refraction to be 0:0018. In quartz it is 0°0094; in Iceland spar 0°172. Hzxperiment No. 5. Main’s Apparatus——The specimen was a piece of glacier ice (B). The measurements were taken with the cathetometer. We had already found, in the other apparatus, that glacier ice would stretch, but. we thought it desirable to confirm the fact with a different mode of measurement, So in this one case we used the _ cathetometer again, in spite of its disadvantages for this kind of work. The length between the needles was about 20 cm., the area of section 7°3 sq. cm.,and the tension 2°7 kilos. per sq. cm. The second Glacier Ice B. Length between Needles 20 cm. ‘Tension 2°7 kilos. per sq. cm. ce Batck Temperature. Date. ture at the | Interval.| Extension.| per hour time. per 10 cm. Week Wien: hours. mm. mm. Feb o. Or ht. e —2 ae 5 a ~ro ~ro ee 9-5 24 0°78 0°0160 |—2°5°| —3°5 16 h. 30m . ‘ . - ot - me sein | 3 16°25 0°44: 0°0185 |—2°5 | —4°5 12 —4 13, 16h. 45m.) —0°5 32 0°53 0:0083 |—o-5 | —3-0 PEOEA sn scala sae as ee 72°25 1°75 0°0116 ) 352 Messrs. J. C. McConnel and D. A. Kidd. [June 21, column gives the temperature just before each observation, the fourth the actual extension during the interval in millimetres, the error probably not exceeding 0°] mm., the fifth the rate per hour per length of 10 cm., and the two last the maximum and mean temperatures. during the interval. On the 10th and 11th the ice broke at the collar, and had to be frozen together again. It will be noted that the rate of extension decreases with the time, more than can be explained by errors of observation, though the tendency of the temperature is to rise. Experiment No. 7. Main’s Apparatus——The same piece of ice was used, cut a little shorter (glacier ice C), and fitted with wire indicators. Only one scale was used for the two indicators, so the readings cannot be trusted beyond 0°5 mm. on the scale. As the multiplication was generally about 16, this gives an error in the actual extensions, when small, not greater than 0°03 mm. When the extensions are large the error is greater, owing to an uncertainty of - perhaps 10 per cent. in the multiplication. The “needles” were glass tubes. The length between the needles was 18 cm., and the area of section 7:3sq.cm. ‘The first column gives the time of each reading, the second the temperature at that time, the third the interval between two readings, the fourth and fifth the extension shown by the outer and inner indicators, the sixth the mean rate of extension per hour per length of 10 cm., the seventh the tension, the eighth, ninth, and tenth the maximum, minimum, and mean tempe- ratures, during that interval. On the 17th February the tension was increased by one-half, and the ice in consequence broke at the collar. It was frozen in again, and the tension reduced to the original value. On the 8th March an hour was occupied in readjusting the wire indicators. The sixth column shows a rapid decrease of speed for the first five days, followed by fluctuations due apparently mainly to the temperature, the rate at —4° being about double that at —9°. An addition of one- half to the tension increased the rate 500 per cent, for the first two days of the change. This increased rate in its turn showed a tendency to sink, more or less counterbalanced by the rising tempe- rature. The fourth and fifth columns show the curious way in which the more rapid extension alternates from one side to the other. This piece of ice, taking the two experiments together, was under tension for twenty-five days, and extended altogether about 6 mm., v.e., about 3 per cent. of its length. At the close of the experiment the divisions between two or three of the crystals at one point of the bar almost amounted to cracks, and at that point there was a decided twist in the bar, estimated at 10°. There were a great many bubbles. in the ice, and the crystalline structure was very complex. There was no particularly large crystal. es fae) a 2 . = F00-0 BG= (0° 229s 7. 6= : 0600. 0 : = 0-9- | 04-] 0¢8-]| “ | g200-0 = eo eee | eg | 8900: 0 S zg— | ¢9—| ¢g.e—|¢g.¢]| otto-0 : ee=— ao —"| 4p Es 8100-0 S Gea | ap =—{ 3.2— i 6200-0 S Ces hes pepe s 1Z00- 0 as oer OSes t= | a. | Senow ~ Oj |p o-8e— | ORs) i S100. 0 = Gre. Oe | 0.92). e100: 0 8 OukS ip S-Or=—4 e.g == -* ZP00- 0 is] q oa P— locesh — | o2-S— | SE. | 990020 3 “cru S ove) a “UBOTL “UTA, xe] aod | ‘uo OL rod ‘sO[Iy | anoy «sod uors oyey ‘ernqetod ata J, -U9J, 1888.] ; gc. 8-& GL. 0 16-0 84.0 99-0 69-0 $¢.0 76-0 16-0 a 0) 1-0 6T-0 cé.0 G3: O ST-0 6T- 0 Z0-0 GI. 0 FI-O GZ. 0 60-0 60. 0 6T- 0 TE-0 G<- 0 “ULUL “UU ‘rouUuy | ‘104nCO *MOISUIIXG &6 ‘san0y "[BAdoqyay Z.o— OT aa 6-G— ¢.9— ave g.7—- 6-4 oC 0-9-— 23 3g — €-4- 00: G— “OUIT} Se aainjered -W9 J, "UD QT SO[PeeN Woomyog YASUerTT “— BOT AoIORLH eee ee eee eee cee ee ee ee ese ee eevee eee ** [BOT 0 OG ‘YT OL ‘6 (a9 eeree (9 °9 a9 sa eee 16 “Pp ce mcr TS “ ‘Avy on ee UG °6Z ce ee eo mich We ase = seeee a | 6 ‘eg (49 c ‘eg (79 DRONES 6p g Cr cig | 8 TZ a4 “uL0g 16 ‘BT “ eeee GRC Ts Teel “ss = eooeee 16 Hae ce eoeee “Uy OL ‘OL ‘qaq ee ‘9}°q We now come to the experiments made with the rough apparatus. At first it fully deserved the name, but later on, viz., in Experiments 6, 8, 9, and 10, the results were quite as trustworthy as in the more elaborate arrangement. Heperiment No. 3. Rough Apparatus——The specimen was a circular cylinder frozen in Main’s mould, about 20 cm. between the needles. 354 Messrs. J. C. McConnel and D. A. Kidd. [June 21, The area of section was 6 sq. cm., and the tension 4 kilos. per sq. cm. The measurement was taken with glass indicators. A long straight glass fibre was used as indicator, bent at one end to hook under the lower needle, and svpported in a nearly horizontal position by a glass connecting fibre hooked over the upper needle. The vertical scale was attached to an arm projecting from the upper iron plate. During the first 22°5 hours the ice extended 3°7 mm. on the outer side, and contracted 0°75 mm. on the inner side. During a sub- sequent six hours it extended 1:7 mm. on the outer side and 0°6 mm. on the inner. The mean rate per hour per length of 10 cm. was therefore 0°046 mm. The temperature is not known with any certainty. This ice was never examined under the polariscope, but owing t0 the mode of formation described fully at the end of the paper, we may be certain the structure was in the highest degree irregular. It was probably, however, tolerably symmetrical about the axis, so the bending may be attributed to the eccentric application of the pull. Heperiment No. 4. Rough Apparatus.——The specimen was a piece of glacier ice (A), composed of perhaps a dozen “grains’’ very irregularly arranged, the axes of some being at right angles, of others parallel, to the length. Distance between needles about 22 cm. The area of the section is a little uncertain, as it was not measured wn situ, and the ice was not protected from evaporation. It may be taken as 6°5 sq. cm., and the tension as 1°66 kilo. per sq.cm. The ice was subjected to tension for about eighty-five hours altogether, but we only give the results for the last twenty-seven, as at first the indicators appear to have slipped, and, after precautions had been taken to prevent slipping the two indicators happened to come in contact. The indicators were arranged as in the last experiment, but the readings were improved by attaching a mirror to the scale. The multiplication was about 30, and the extensions may be trusted to 0:03 mm. The first column in the annexed table gives the time of each reading, the second the temperature at that time, the third the interval between two readings, the fourth and fifth the actual extensions measured by the outer and inner indicators in that interval, and the sixth the rate per hour per length of 10 cm. The temperatures are somewhat uncertain, as the ice was not enclosed in a box, and the temperature of the room was very far from being uniform. The last four temperatures were taken by a thermometer hung close by the ice and on the same level. The minimum of the night by this thermometer was —3°3°. The high temperature at 21 h. 15m. was due to the window of the room having been nearly closed. It was then thrown wide open, so the temperature must have soon fallen again. So the interval before this reading, 0:0°, would probably be much warmer on the average than the subsequent 1888.] _ On the Plasticity of Glacier and other Ice. 355 Glacier Ice A. Length between Needles, 22cm. Tension 1°66 kilos. per sq. em. Extension. J Rate Date. Tempera- iniews)..\—— —— ae er oer os er 10 cm Outer. | Inner. P ; hours. mm. mm. mm. Feb. 3, 9h. eeeveesesseeses BRINE | ; a7 0:23 0 ‘02 0:015 Pea 4am. 2.2...) ~1°0 a° 13 0°19 0:01 0:013 ere Me SUM. .....- —4°0 4°75 0°35 0°10 0-022 39: 39 21h 15m 0°0 11°25 0°53 0°16 0°014 ” 4, 8 h 30 m —3 0) 3°50 0°19 0-08 0:018 3) ”) 12 h. Cece esreereceve —1 0) Total 27°0 1°49 Gai 0°0156 interval. Thus the sixth column shows that the ice became more plastic as it neared the thawing point. The unequal extensions in the fourth and fifth columns may well a been due to eccentric application of the tension. Kzperiment No. 6. Rough Apparatus.——The specimen was an icicle trimmed with a knife to an uniform circular section. The apparatus was greatly improved. The new mode of suspension was adopted, specially arranged, as described above, to ensute the tension acting along the central line of the bar. The indicators were hooked over the top needle and bent at right angles so as to point downwards, as_ in Main’s apparatus. They were of glass, and no thoroughly efficient means was taken to prevent slipping along the needle, but we do not think any slipping can have taken place during the observations quoted below. The whole apparatus was enclosed in a jacketed box— which was, however, generally left open at night—and a centigrade thermometer, graduated to tenths, was hung in the box on a level with the middle of the ice. In the table the fourth and fifth columns give the actual extensions during each interval, which may be trusted to 0°015 mm., and the sixth column the mean rate of extension per hour per length of 10 cm. The second column gives the reading of the thermometer at the time of the observation, and the last two columns the maximum and mean temperatures of the ice during each interval. These are tolerably accurate, as many observations were taken besides those here quoted. The ice was not protected from evaporation, so the [June 21, Messrs. J. C. McConnel and D. A. Kidd. 306 0-0 0-0 8-0- 0-0 0-6- L.0- SE] Ge 0-0 0-0 0-0 6-0- 0-0 6.L= L-0- 08: 6— o0-S— “UBOTT UINUITXB YL ‘oanyerod ute 7, Pn ee QA A. MN ©) oe Nici “OTJOULIJWIO orenbs tod *soyly ‘HOIsua J, 8200-0 TV00- 0 Z200. 0 $&00-0 ¥c00- 0 Z€00- 0 ST00- 0 9600-0 ‘UO OT tod amoy rod 938 \7 "ULO GT ‘SOTPSONT WOEMJOq Youer]T 98-0 8P-0 00-0 $€0-0 040-0 S9T- 0 020-0 $10. 0 0.0 OOT- 0 SOT: 0 040-0 Sv0- 0 0-0 040-0 gE0-0 “UU uur “LOUUT "19}]NO “UOISUO4 XT 82, oes eee? eae eee eee Oa G.O+ eeee “Ul CF ‘USL “ 19 $1.9 9.0+ ae a Ue as ‘eT (79 g- 9T LO Fla ~ Use POLS = | 0-4 eS |S aoe ES pT. 0.81 G.O+ ee EC Raye gre ‘1 OZ 6c “ec a2. 11 ! S20 | ee Ue Sele g- OT 1.0- : weree ‘1 OL 66 (43 Gh. L-6- 22D. WILKE ‘1S ‘OT (73 g- OT 00-2 OTD ee Tae OM *sanoy “OUT 80 B i ound seul “O[OLOT — 1888.) On the Plasticity of Glacier and other Ice. 357 section gradually diminished, and the tension consequently increased, as given in the seventh column. The mean section was about 4'] sq.cm. The ice was under tension for twenty-four hours previous to the observations given below, but during this time the indicators seem to have slipped. The weight was removed for twelve hours on the 14th owing to the thaw. It is curious to notice how irregularly the extension is divided between the two sides; the ice bends first one way then the other. The fluctuations in the mean rate of extension seem mainly due to the temperature. During thirteen hours at a temperature between —1°5° and —3:0° the rate was 0°0028, while during thirty- eight hours at a temperature above —0°7° the rate was 0:0034. The ice was full of minute bubbles, though not in sufficient quantity to make it quite opaque. The component crystals were very small, less than a millimetre in diameter, and with optic axes arranged quite irregularly. Experiment No. 8. Fiough Peps —The specimen was a piece of glacier ice (D). The wire indicators and connecting fibres were hooked through wire loops firmly fastened to the glass needles em- bedded in the ice, so there was no possibility of slipping. The multiplication was about 22, so the small extensions are accurate to 0°02 mm. The area of section was 6°3 sq.cm. ‘The table is arranged as in the last experiment (6). Thus the whole extension in three and a half days was more than 4, per cent. of the length. At 20h. 15m. the inner indicator had moved off the scale against a stop, so the extension was probably rather greater, certainly not less than that given. ‘The extension ata particularly low temperature, mentioned in the general summary, was between February 18th, 21h., when the temperature was —9°0°, and February 19th, 9h. 15m. There was a contraction on the outer side during this interval of 0:01 mm.,and an extension on the inner side of 0°23 mm., so the mean rate per hour per 10 cm. was 0°0065 mm. It should be mentioned that the points on the glass needles, where the indicators were attached, were not quite close to the ice, but at the distance of a centimetre perhaps. Hence, while the mean rate is correctly given, the extension on the inner side of the bar is ex- ageerated, and that on the outer side made too small. Taking the ice as 2°5 em. thick, this consideration leads to the result that the total extension of the outer face of the bar was 2°9 mm., of the inner face 9°7 mm. This experiment shows how completely the plasticity depends on changes in the internal structure of the ice. Thus, for the first two days we find, under a slight stress, a moderate rate showing some tendency to decrease more rapidly than can be easily attributed to the fall of temperature. An increased tension produces as usual a ro a he a (ax rd S| a or) S| | fe) =) (2) = a) far) w n MQ oO = 308 | | | | a I VW HTH MO MODANA A I coo SOCOM FAR MOBW HON DD or O wh ° = oe) | “UROTL I — re AN eS Cra | ~ANHHNOARAS SH So} OD COD ON Lol db po Ses © 10 We | ‘XV]l = zs L¥-3L | 12-0+ . €b0-0 | €8:0 | 91-0- * OIT-0 | 44-0 | 90-0- ss G9z-0 | OT-T 0-0 08: T cg-0 | 04-0 | 90-0+ r 88-1 | 44-0 | 31-0+ 8-1 | OT-T | 68-0+ . G9-0 | 89-T | ST-O+ ¥ csr-0| 6-0 | 80-0+ 09-2 82z-0 | 8-0 | T0-0- €0- T 010-0 | 62-0 | 90-0+ - ¢S0T-0 | d0@-T | 60-0- . 821-0 | 66-0 | 80-0- “ €0T-0 |- 48-0 | 10-0- GG. Z 920-0 | €8:0 | 90-0— - G400-0 | 38-0 | $0-0-— oy 1400-0] 61-0 | 10-0+ - 7900-0 | 82-0 | ¥0-0- GP-T | 2610-0 | 42-0 | 80-0- “TUL “UU aro "bs EO “LOUUT *L091.OC lane moy 10d,| —_ : 04 “MOISUOJX TT ‘ornqvarodute J, Gg. €8 g-¢ GS. g-T g4-0 91-0 6&- 0 0-1 ¢Z-0 g-0 G- 31 GL-& 09-6 6-1 GL-§ G4. 8T 0- OL GS. OT 0-4 *‘sxnoy [PALOqUT | , Soyey MN oD | ROMA RSAMMAMANNNA a | cOobnU YE AoE Er SeADOE re i | ° ay eo) | “OULTY oT} 48 imyerod -WO J, eeeeoeee oe eT BIT, S. BEOS MS teeeeeeeygT « ee ey ee mae 8 Dg lM ‘urge GIL emg TIT « eS ae EE 6¢ SS ames arene 8 6 sP Tone Tet G (74 “Mm Sh ES ‘1S “met Tog “ SEO MGI PPS OHEIMA seas 8 RTT aTp TE 6é ® “Ul OP "THOT. (%5 pas bongs + as 0Z oss 0G Taal GT ce se eereee POP OYE ‘BL ‘qo ee SUne T6561 poset ee ge Say, (14 ‘oye ‘HO PT ‘SOTPOON WoeMyoq YASUE] “(7 90] AOLOV]H) (a3 A But But it has further the remarkable as soon as the former tension is restored, the acceleration continues effect of transforming a slow retardation into a rapid acceleration. light tension now reduces the velocity to nearly the old figure. large increase in the velocity. It is true that this acceleration was attended by a rising temperature, but it seems far till the velocity reaches nearly 2 mm. an hour. too great to be attributed to that alone. We may fairly conclude that the process of extension itself has sometimes the effect of increasing the apparent plasticity. Reducing the tension by one- third brought down the veloc ity at once by four-fifths, and, strange 1888. | On the Plasticity of Glacier and other Ice. 359 to say, impressed a gradual retardation in spite of a rising tempera- ture. It would thus appear that in this case, while a rapid extension increased the plasticity, a gradual extension had the effect of diminish- ing it. This is an anomalous result, but it must be remembered that we are measuring the sum of a large number of independent actions. The behaviour of the whole is probably much more com- plicated than that of any one of the individuals. _ Being curious to see the effect of great tension, we applied 42 kilos. per sq.cm. This brought the experiment to an end, for after half a minute the ice gave way. It was found broken both at the lower collar and at.a point below the upper needle, where we had previously noticed a crack extending part of the way across the bar. At which point it broke first we cannot say. The bar was examined at the end of the experiment. It was nearly straight in spite of one side having extended so much more than the other. It contained several large bubbles, one perhaps 2 cm. long, drawn out into very irregular shapes, which seemed to show this piece had suffered great distortion while it still formed part of the glacier. It contained part of a very large crystal which composed, perhaps, one third of the whole bar, and ran three quarters of the length between the needies. _ This crystal occupied one of the angles adjacent to the inner face, which extended so much. Its optic axis was inclined at perhaps 70° to the length of the bar. Experiment No. 9. Rough Apparatus.—The specimen was a bar of lake ice, with the crystalline columns parallel to the length of the bar. The section was 8 sq. cm. in area. The arrangements were the ‘same as in the last experiment (8). The extensions are so small that the deduced rate during each interval would be very inaccurate. We have therefore given, in the second, third, and fourth columns of the table, the extensions measured from the length at the time of the first reading and reduced to the proportionate value for a bar 10 cm. long. They are probably correct to 0°01 mm. The fifth column gives the temperature shown by the thermometer at each reading; and the next three the maximum, minimum, and mean temperatures of the ice during each interval, estimated from a large number of observations not quoted. Previously to 15h., February 28th, the ice must have been thawing, probably for about an hour. The weight was removed for the next three hours. The total extension during 208 hours per length of 10 cm. was 0'°145 mm. on the outer side, and 0°048 mm. on the inner, giving a mean rate per hour of 0'00046 mm. The mean rate during the first 168 hours was 000039 mm., and during the last 40 with the heavier weight 0°00076 mm., notwithstanding a slightly lower mean temperature. But these rates were so small as to be beyond our means of accurate measurement. [June 21, ‘avok s1q} Lavnaqo 7 ut skep GZ OOM OLONT, » NS Messrs. J. C. McConnel and D. A. Kidd. 360 ‘ULO OT ‘SOTPOON UOOMJoq YZoUOrT 8P0-.0 ‘SUtUN[OL*) 03 joT[Vavd oo] o3NrT 0-9- 960: O CPrI-O a re Me ‘9 (73 8-3 ¢.G—- oa 0-7 0-G¢— 990-0 ¥60-0 80T- O Ee UL te Lee 1 4 0-G¢=— Ose 0-I- 0-I- ¥S0-0 PZ0-0 G80. 0 pT eee eae 0-0 0. 3+ PSO. 0 ~Z0-0 G80- 0 pA Seo Gee et ae 1-3 0-6- Ey 0.0 | oe FSO. 0 960-0 640-0 ne a ee a aa Pete L3G oom ¢.7- 0-6 0O-P- 920: 0 410-0 980-0 Oe eG: Oa LG AO) G4 ae 90-8 00: bP PR) al fa 0.0 0-0 0-0 Prey Poe ea Te ee “eu "UU *LUUL "CUUL pea uvoT WIN UIT AT WUNWIXBp, | “our, og FV Uv], - LOUUT 10400 ‘bs aad *soy[ty —<$<—— $$ —_—_______ 04U(L. UOISUOT, ‘oungearod way, ‘Wd OT tod uo1sudzxny 1888. | On the Plasticity of Glacier and other Ice. 361 Examining the bar at the end of the experiment, we counted about thirty columns in a section, most of which ran the full length of the bar. The largest had a sectional area of about 35 sq. mm. Haperiment No. 10. Rough Apparatus.—T he specimen was a bar of lake ice, with the crystalline columns running obliquely across at an angle of 45° to the length of the bar. The area of section was 5°59 sq.cm. The indicators, &c., were arranged as before. The tem- perature at the time of observation, and the minimum temperature were observed ; the maximum and mean temperatures are estimated. The fourth and fifth columns give the actual extension during each interval. They are probably correct to 0°02 mm., as the multiplica- - tion was 35. The rate shows a decided tendency to decrease, only slightly checked by the rise of temperature. The glass needles were put at right angles to the columns as well as to the length of the bar. [June 21, Messrs. J. C. McConnel and D. A. Kidd. 362 ¥ “ o STO: 0 8-3- 2 aa OD ev PTO. 0 a dad 8-g— €.€- T1O-0 0-g- 4-9- €.€- €10- 0 0. 9— 74S a ya OT9- 0 4-9— Bomar 9.g—- FLO-0 L.9- a2 oo PIO: 0 08+ G— ol -9— of: S— PEO: 0 “ua “UCNLULTUT “ULNWIX® 3 a a3 clea ‘aanyerodure J, ma! ‘uo ‘bs aod ‘soy G7.g ‘MOIsuaT, ‘WO @.TT ‘So_peoN UeOMy0q Y}SUOT] 64-1 g8-0 IT-0 PIO 16-0 LT-0 FL-0 GI-0 96-0 OT. 0 91-0 OT. 0 6v-0 GL: 0 Gv: O 60-0 “ULUE “UU ‘LOUUT ‘10nQ "MOISUO4XA S-64 8 ST 6 oT 8 LT g-9 “Sanoyy "[RALOJUT mm re ee | | | | ee | eA vv ere tle pat Si rene eae ie 5 lee oi cee & Pega are Shr a 9.9— os Stirs gaa “ S| Bae 39 aoa e.g O97 |S imoe Yee omgurodtuay, and "SUUIN[OD oy} 07 onbijqo so] oyery (73 cc 66 (74 (73 1888. | On the Plasticity of Glacier and other Ice. 363 We shall now describe the experiments on compression. An oblong piece of thick plate glass was laid on the table, and on it were placed three square blocks of ice, at the angles of an equilateral triangle about 9 cm. in the side. On the ice was laid a second piece of plate glass similar to the first, and pressure applied by means of a lever at a point immediately over the centre of the triangle. Measurements were taken with callipers of the distance between the plates at three points on the edge, such that each point lay ona line through the centre and one angular point of the triangle. By drawing a diagram to scale, it was not difficult to deduce from these measurements the yielding of each block of ice. To prevent slipping, we found it necessary and sufficient to freeze a slip of paper on each end of a block of ice. A maximum thermometer was placed on the table close by the plates, and covered over with the same cloth, so that it probably gave the temperature of the ice within a degree. The horizontal section of each block was 7°5 sq. cm. in area. The fourth, fifth, and sixth columns give the actual contraction of the blocks during each interval. They are correct probably within 0°02 mm. Hach measurement with the callipers was repeated, and the two readings seldom differed more than 0:02 mm. Pressure had been applied for one day previous to those here given, but owing to an accident, its magnitude was rather uncertain. The remarkable difference between the plasticity of three specimens of glacier ice is well shown, though in this case all three pieces were from the same lump. After the experiment they were examined under the polariscope. All three were composed of smallish grains averaging perhaps 7 mm. in diameter. The increase of plasticity for arise in temperature from —6° to —3° is very striking in all three pieces. Experiment No. 2 on Compression.—In this three pieces of lake ice were arranged as in the last experiment. The crystalline columns were vertical, so that the pressure was applied in a direction parallel tothem. The horizontal section of each piece was 7 sq. cm. The fourth, fifth, and sixth columns of the table give the contractions during each interval, calculated from the readings actually taken, as explained in the description of the last experiment. They are pro- bably accurate to 0°02 mm. It may be mentioned that the totals are calculated to an extra place of decimals, which explains the slight discrepancy observable. VOL. XILIY. Lo re Messrs. J. C. McConnel and D. A. Kidd. [June 21, 364 0O-T— ee 960-0 8ZT-0 880-0 Ave iSaR Aas OURS 6 Asa nettar eae ara. e 9 ey re a OT sod 0-4- = S| & 00-0 ZL10-0 9600-0 [trttesttsst+sssdup upp pus ‘pag ‘pug | OU 74 Oe a ie GZ. 0 66-T 8T-T OZT a ae ee LENO, 8.% al eoeereeeceoe 6c ‘9% ce 0-F— 8-o—- 8T-0 VoL 19-0 VG ~.9 pe ee ee eb es ee (13 ‘eg, (73 CRS Tae L-0- 60: 0— OL-0 90-0 VG | P.6 = eeee ee 08 oe (19 4 (3 2 ch 00-0 LT-0 60-0 VG ae ©2008 ©6800 ©e ce ‘ez (74 0:7 0-7—- 60-0 60-0 g0-0 VG | . 0-21 ©8008 0090000 66 BS ce ob} 9— 08: G— 90-0 0€-0 Ls-0 VE oe © a reg ae Boe ee ATG TZ “qai7 "TUT “UU “TU "SNOT “UvOTL “UNUM XT 5) A f ac : ‘ouIT} OT 4V ; Ieee omnyearoduray, se ‘oanqeroduna 7, "UOTIOBAZWOD ‘m0 ‘bs aod ‘sojry %.g oanssorg ‘WO ¢.g ‘yySuer] [eyTUT ‘ooT TolOVpH Jo soostd ootyy, “[ ‘ON JuouLsedxy uoissordut0/ ‘) je ad P 365 On the Plasticity of Glacier and other Ice. 1888.] ee ee os fie, o-0— 0:-9- L-¥- 0-4- L.9- 90: 9 ne 06: C= WROTL “UINULIX® JT ‘ornjzerod may, 8T00- 0 6100-0 6000: 0 pe 00-0 S€0-0 ¢00- 0 €8 10-0 00-0 00-0 VG 10:0 00-0 00-0 VG 10: 0 60-0 10: 0 VG 60-0 c0-0 00-0 IL "UU “UU "TUT “SIMO, e) ‘a ‘Vv a *[@ALOJUT “UOTJORIYMOD ‘uo ‘bs aod "SOTTY 2.8 “OUNTT OTT} 7B eunqetod uta J, { oa imoy sod yey eeseeoe eee "* "dd OT [830], cc iy)! 4 cc we. ce 79 ‘g 74 Ty 6 7 ce ZS ‘Gg ‘ABIL ‘aqeq INsselg ‘Wd F.c ‘YZdueTT ‘“SUUIN[OD oY} SuO[e possordutoos soy OYeT = *g “ON quomriod xo woissord 09 | 366 On the Plasticity of Glacier and other Ice. [June 21, Thus the yielding of one piece was well within the errors of obser- vation, of the other two only just perceptible with the instrument employed, and this small yielding may well have taken place entirely in the thin layer of irregular ice with which the paper was attached. In the early part of the winter we made, as already mentioned, a large number of experiments on obtaining ice in the mould* free from air bubbles. We were ultimately successful, and, though our experiments proved to be of little use for their immediate object, they are of some permanent interest as tests of various methods of obtaining air-free water, so we shall describe a few typical ones. Main, the previous winter, boiled the water and let it freeze, then melted it in the mould, boiled it, and let it freeze again. The result was clear ice, except for ‘‘a small core of minute bubbles up the axis of the cylinder.” By Main’s advice we procured an air-pump adapted to exhaust the air from the mould. Between the pump and the mould was a good stopcock, which would maintain the vacuum for several hours. When in good order the pump would boil water at 40° C., or below. We found that this degree of exhaustion was far from removing all the air, even when applied for five hours. Boiling for half an hour, cooling sub vacuo, and freezing at atmospheric pressure under oil was more successful, but not satisfactory. We froze the water at atmospheric pressure to make the bubbles small, having placed a layer of oil on the top to prevent air entering. The next method proved much more effectual. We kept water sub vacuo for twenty-four hours at about 70° C., and let it cool sub vacuo, only admitting air after the freezing had begun. There were a few exceedingly small bubbles visible at one end of the rod of ice. Thawing this sub vacuo and keeping it again for twenty-four hours sub vacuo at 70°C., we got rid of the last traces of air in the rod, though there were a few in the large cone of ice. [ We conclude that, to free water from air, it should first be boiled till most of the dissolved air has escaped, and then left for a con- siderable time without permitting any air to have access to its surface. Boiling should be repeated at intervals to remove the air, which gradually escapes from the water and mingles with the aqueous vapour in the space above. It is probable that a high tem- perature quickens the process.—July 6, 1888. |] The utter irregularity of the crystalline structure of the mould ice is an obvious consequence of the mode of formation. The first ice formed, no doubt, is a layer on the surface, but the centre of this is soon broken though by water forced up from below, owing to the expansion in freezing. So what we observed in its various stages was * This was the iron mould used by Main to form a round column of ice 2°8 cm. in diameter and 24 em. in length, with a conical expansion at the lower end of perhaps half the volume of the column. d 1888.] Organisation of Fossil Plants. 367 a ring of ice formed at the surface, which gradually extended down the sides and towards the centre, till we had a long tube of ice thinning out towards the lower end joined on to a case of ice, lining the inside of the cone. The tube grew thicker and thicker, till it became a solid bar. When a piece of sheet india-rubber was laid on the surface (to prevent air entering), it was frozen firmly to the sides of the mould, while the centre was pushed upwards into the shape of a bee- hive, till at last it burst. It was curious to find the india-rubber with the middle part drawn out into a long tube with torn edges, firmly imbedded in the ice at some little distance from the end. In conclusion, we wish to express our thanks to Dr. Main for the use of his special stretching machine, and of the various thermometers, callipers, and much other apparatus, which he has generously placed at our service. In case any reader of this paper should be kind enough to offer us any useful suggestions, or on the other hand should desire further information on any point, we give here the permanent address of one of the authors, James C. McConnell, Brooklands, Prestwich, Man- chester, England. We may add that copies of papers bearing on the subject would be particularly acceptable. VY. “On the Organisation of the Fossil Plants of the Coal- measures. Part XV.” By W. C. Wiiamson, LL.D., F.R.S., Professor of Botany in the Owens College, Man- chester. Received June 13, 18838. (Abstract.) The author describes and figures a series of specimens which throw new light upon Corda’s two genera Zygopteris and Anachoropteris, as they are adopted by M. Renault, but which specimens show that both these genera can no longer be retained, even by those who approve of such multiplications of ill-defined genera. He proposes, therefore, the abandonment of Anachoropteris and the retention of Zygopteris, so that “‘ Zygopteroid” may be employed as a descriptive adjective in connexion with some specially remarkable forms of petiolar vascular bundles. Under the name of Rachiopteris hirsuta, a new group of freely branching stems or rhizomes are figured and described, characterised by having the exterior of their bark abundantly clothed, especially in what appear to be the younger shoots, with remarkably large curved multicellular hairs, closely re- sembling those similarly located in the young shoots of the Marsilee ; numerous cylindrical roots radiate from these axial organs. Under the provisional name of Rachiopteris verticillata attention is alsu 368 Mr. G. Gore. Effects of different Positive Metals (June 21, called to some curious roots, the secondary branches of which are given off in regular verticils; besides these plants two other distinct kinds of roots are described, in each of which the cortical parenchyma is characterised by containing numerous lacune of the type so com- mon amongst aquatic and semi-aquatic forms of vegetation—e.., Nymphea. All the above objects are from the Lower Carboniferous beds at Halifax. VI. “ Effects of Different Positive Metals, &c., upon the Changes of Potential of Voltaic Couples.” By G. Gorz, F.R.S. Received June 13, 1888. The following effects upon the minimum change of potential of a voltaic couple in water (‘ Roy. Soc. Proc.,’ May 26, 1888), and upon the change of potential attending variation of strength of its exciting liquid (ibid., May 31, 1888), were obtained by varying the kind of positive (and of neyative) metal of the couple, and by employing different galvanometers. The measurements were made by the method of balance, with the aid of a thermo-electric pile* (‘ Birming- ham, Phil. Soc. Proc.,’ vol. 4, p. 180), and the numbers have been corrected for errors caused by absorption of hydrogen by the platinum. The water employed was ordinary distilled water, redistilled after addition of a minute amount of sulphuric acid, and was quite free from ammonia. Table I—Mg + Pt + HCl in 465 grains of Water at 17° C. Grains. Volts. Grains. Volts. 0°15 1:7119 0 °0458 1°6861 0 °185638 1°6946 0 -0308 1 ‘6804 0°12066 1 °6804 0:°0158 1 °6746 0°10569 5 0 :0009 1 °5946 0:09072 a 0:0008 1 °566 0 :07575 1°6861 || water ‘ 0 ‘06078 +5 Ms With an ordinary astatic galvanometer of 100 ohms resistance, the smallest proportion of the anhydrous acid required to change the potential, lay between 1 part in 516,666 and 570,000 parts of water; * This instrument is manufactured by Messrs. Nalder, Brothers, Horseferry Road, Westminster. 1888.] — upon the Potential of Voltaic Couples. 365 but with a Thomson’s reflecting one of 3040 ohms resistance, it was between 775,000 and 930,000. The effects obtained with zinc as a positive metal have already been given (‘ Roy. Soc. Proc.,’ May 31, 1888). With that metal and the astatic galvanometer the minimum proportion of acid required to change the potential lay between 1 part in 9,300,000 and 9,388,185 parts of water; but with the reflecting one it lay between 1 in 15,500,000 and 23,250,000. Notwithstanding the electromotive force of magnesium is so much larger than that of zinc in the very dilute acid, the minimum propor- tion of the acid required to destroy the balance was very much smaller with zinc than with magnesium, and the increase of electro- motive force was more rapid with zinc than with magnesium. The minimum proportion of acid required to change the potential with magnesium (‘ Roy. Soc. Proc.,’ May 26, 1888), or with zinc, was nearly the same, whether the couple was balanced by a precisely similar one or by the thermo-electric pile. The order of variation of electromotive force by change of strength of the liquid was very similar with zinc to what it was with magnesium, and the curves generated by plotting the results were much alike. Table I.—Cd + Pt + HCl in 465 grains of Water at 17°5° C. Grains. Volts. Grains. Volts. Grains. Volts. O15 0 °9494 0:07575 0:9108 0-0009 0°7678 0-13563 0°9108 0 -06078 0°9251 || 0-00081 i: 0 °12066 ee 0°04581 0 °9427 0 00073 0°7478 0°10569 a 0° 03084 a water 4 0-09072 és 0 -01584 0°9451 a With the astatic galvanometer, the smallest proportion of acid required to alter the balance was between 1 in 574,000 and 637,000 ; but with the reflecting galvanometer it was between 1 in 1,162,500 and 1,550,000. The order of change, or curve of electromotive force by variation of strength of liquid, was somewhat similar with cadmium to what it was with zinc and magnesium, 370 Mr.G. Gore. Effects of different Positive Metals [June 21, Table IJI.—Al + Pt + HCl in 465 grains of Water at 16°5° C. Grains. Volts. Grains. Volts. 0°15 0 :9003 0 -06078 0° 8431 0°138563 0-866 0°04581 0°8288 0:12066 0°8517 0°03884 0 °823 0:°10569 0 °8345 0 °03084 0°8145 0°09072 0°8431 |. water 5 0 ‘07575 0°8517 aie With the astatic galvanometer, the minimum proportion of acid required to change the potential lay between 1 part in 12,109 and 15,000 parts of water; but with the reflecting one it was between 1 in 42,565 and 46,500. The curve of variation of electromotive force, by uniform change of strength of liquid, was less regular than with either zinc or magnesium, but presented certain points of simi- larity with the curves of zinc, magnesium, and cadmium. The following table shows the proportions of the acid required to upset the balance of each of the preceding couples in water :— Table IV. ; With the Astatic Galvanometer. Zn + Pt. Between 1 in 9,800,000 and 9,388,185 Cd + Pt. . » 1 jo574,000 aaeGeaaae Me + Pt. 1, “S1e666 ayaa AY Bt. 1 18109) re With the Reflecting Galvanometer. Zn + Pt. Between 1 in 15,500,000 and 23,250,000 Cd + Pt. yc. Lis, Jp(62,800 von sleaanl aa Me + Pt. sv bap 775,000 5 i Octane Al + Ph. «1», 42,068, Table V.—Mg + Pt + Iodine in 465 grains of Water at 14°C. Grains. Volts. Grains. Volts. 0°132 1°5318 rose to 1°777 0:0546 1°4541 rose to 1°777 0-119 i ! 00417 | 1°522 0:1062 1 Stee es 00288 | 1°5588 0 -0933 oh 00159 = > > DeOsAi al.) 1a 2 0-003 i 0:0675 | 1°4598 a a . ——-:1888.] upon the Potential of Voltaic Couples. 371 The electromotive force in the seven strongest solutions rose quickly after immersion; this was due to an extremely thin solid coating forming upon the magnesium. Table VI.—Ditto at 19° C. Grains. Volts. Grains. Volts. 0°00099 1°7018 0:000723 1°5588 0 00089 1°7089 0 -00066 a 0 -00088 1 -6589 0 -00033 i" 0 -000805 1 6446 | water = With the astatic galvanometer the minimum proportion of iodine required to alter the potential lay between 1 in 577,711 and 643,153 parts of water. If the magnesium was merely wiped between each measurement, instead of being cleaned with emery cloth, the electro- motive forces on first immersion were 0°18 volt higher in Tables V and VI. The smallest proportion of iodine necessary to upset the balance of a zinc-platinum couple in water has already been published (‘Influence of the Chemical Energy of Electrolytes, &.,” ‘ Roy. Soc. Proc.,’ June 7, 1888); it lay between 1 part in 3,100,000 and 3,021,970. Table VIT.—Cd + Pt + Iodine in 465 grains of Water at 19°C. Grains. Volts. Grains. | Volts. Grains. Volts. ee \ 2 ae | 0°132 0°9884: 0°0675 1-0027 0 -0030 0°8311 0°119 0°9741 0°0546 0°9854: 0 °002625 0°8028 0° 1062 2 0 °0417 1 °0198 0 002325 0 *7882 0°0933 0 °9884 0 °U288 0 °9854: 0 °002079 0 °747 0°0804 | 0°9827 0°0159 0°9741 water e The minimum proportion of iodine required to change the poten- tial lay between 1 part in 200,431 and 224,637 parts of water. The curves of variation of electromotive force by uniform change of strength of liquid with zinc-plaiinum and cadmium-platinum, presented certain similarities, but that with magnesium-platinum was considerably different, probably in consequence of insoluble films forming upon the magnesium. ; 372 Mr.G.Gore. Effects of different Positive Metals [June 21, The following are the proportions of iodine which were required to change the potentials, when the astatic galvanometer was employed :— Table VIII. Zn + Pt. Between | part in 3,100,000 and 3,521,970 Me + Pt. , Tie. 577,711 ,, . G4eiss Cd + Pt. is discs 200,431 ,, 224,637 Table IX.—Meg + Pt + Bromine in 13,950 grains of Water at 12°C. Grains. Volts. Grains. Volts. 0 -000045 1°5757 0 :00003375 1 °5600 0 -0000405 15600 00000225 F 0 -000036 59 water bs The smallest proportion of bromine required to change the balance lay between 1 part in 310,000,000 and 544,444,444 parts of water. The minimum proportion necessary to disturb the potential of a zinc-platinum couple in water has been already given (‘ Roy. Soc. . Proc.,’ May 31, 1888), and was between 1 part in 77,500,000 and 84,545,000. Table X.—Cd + Pt + Bromine in 465 grains of Water at 19°C. Grains. Volts. Grains. Volis. Grains. Volts. 20°1 1:‘8881 13 °26 1° 824 6°42 1°5163 18°39 1 °8709 11°55 1°5492 4°71 1°589 16°68 1 °8538 9°84 1 °5349 3°0 1°543 14°97 1-8307 8-13 ; | | é The strongest solution was a saturated one. 1888.) upon the Potential of Voltaic Couples. 373 Table XI.—Ditto at 19° C. Grains. Volts. Grains. Volts. Grains. Volts. 3°00 1°543 1°65 1°4174, 0°3 1°2801 2°85 is 1°5 > 0°15 1 -2029 2-7 1°5287 135 oe 0°015 1°0456 2°55 a 2 oa 0 :0015 0 °9084 2 °4 1 °5258 1:05 55 0-00015 0°7882 2°25 os 0:'9 T4517 0 -000134 0 °7653 2° 1. 1°5201 0°75 aU 75 Ba id 0 °0001206 0°747 1°95 x3 0°6 1 3932 water Ps 1°8 1 463 0°45 Lesh ye ws a The smallest proportion necessary to disturb the potential lay between 1 in 3,470,112 and 3,875,000. With the solutions from 0°15 to 1:65 grain, the electromotive forces were variable without any apparent cause. The proportions of Hence required to change the potential with these couples were as follows :— Table XII. Mg + Pt with bromine. Between 1 part in 310,000,000 * and 344,444,444), Zn + Pt ‘i = 1 part in 77,500,000 and 84,545,000 Ca + Pt st A lpartin 3,470,112 and 3,875,000 The magnitudes of the proportions of bromine required to change the potential with the three couples varied directly as the atomic weights of the three positive metals. Mg + Pt + Chlorine in 465 grains of Water at 13° C. Sixteen different solutions, varying in strength from 1:0695 grain to 0:03 grain, with a constant difference of 0°0693 grain, gave each the same potential, viz., 2°7336 volls. Much gas was set free at the magnesium, but only in the stronger solutions. Owing to the extreme sensitiveness of this couple to chlorine, several series of measure- ments were necessary in order to determine the minimum point with approximate accuracy, and include the entire range of solution. d/4 Mr.G. Gore. Effects of different Positive Metals [June 21, Table XIII.—Ditto at 13° C. Grains. Volts. Grains. Volts. 0-030 2° 7336 0°015 2°3906 0-027 2°562 0-012 2 *362 0-024: 2 °505 0-009 2°3191 0-021 2°4478 O 006 1 ‘9546 0°018 2° 4192 0:008 1°9118 Table XIV.—Ditto at 13° C. Grains. Volts. Grains. Volts. 0:003 1°9117 | 0:0015 1°9117 0 -0027 3 0:0012 — i 00024. s 0 -G009 a 0-0021 i 0° 0006 * 0 0018 as 0°0003 iS Table XV .— Ditto at 1376 » Grains. | Volts. Grains. Volts. 0 0008 19817. 0 ‘00000117 1°782 0-00015 . 0 00000058 1°7620 0 :000075 "5 0 00000029 1°7248 0 0000375 i 0 -000000145 1°6819 0 -00001875 1 °8249 0°0000000725 1-639 0° 00000937 1°8106 0 ‘000000036 1°6047 0 -00000468 1°7992 0 000000018 1 °5589 0° 00060234 1-7906 water Table XVI.—Ditto in 13,950 grains of Water at 12°5° C. Grains. Volts. Grains, Volts. 0 :000000891 1°573 0 -000000713 1 5589 0 000000821 © “ 0 -0000003565 ,, 0 :000000792 1 5589 water 39 In this table, the delicacy of the thermo-pile was increased by reducing the difference of temperature between its junctions from 100 Centigrade degrees to 00. 1888. | upon the Potential of Voltaic Couples. d75 With the astatic galvanometer, the electromotive force of the couple in water began to change when the proportion of chlorine was between 1 part in 17,000 million and 17,612 million parts of water ; but with the reflecting one it was between 1 in 29,062 millions and 32,291 millions. The minimum proportion of chlorine required to change the poten- tial of a zinc-platinum couple, when the astatic galvanometer was employed, lay between 1 part in 1,264 millions and 1,300 million parts of water (“Influence of the Chemical Energy of Electrolytes, &c.,” * Roy. Soc. Proc.,’ June 7, 1888). Table XVII.—Cd + Pt + Chlorine in 465 grains of Water at 19° C. Grains. Volts. ; Grains. Volts. Grains. Volts. 1-0695 1°71654 0 6537 17339 0 °2379 1°7137 1-0002 1°730 0-5844 17251 0-1686 | 1°7022 O-9209 | 1°7683 0°5151 41-7223. 0 °0993 1 “6856 0 ‘8616 1°7453 0 -4458 1-7165 0°03 1 -6062 07928 1°739 0 :3765 1° 7022 4. bi 0°723 Af 0 °3072 1 ‘6885 Table XVIIT.—Ditto at 19° C. Grains. Volts. Grains. Volts. Grains. Volts. 0-03 1 -6062 0°015 P5175 0 -0003 1°1028 0 °027 “ 0°012 1°4889 0 ‘00010695 | 0°7904 0 °024 Fa 0-009 1 °4603 . 0°00005346 | 0°7589 0°021 1°5690 0-006 1 4346 0°00004806 | 0:7475 0:018 1 °5575 0°003 1°3459 water » The smallest proportion of chlorine necessary to change the potential lay between 1 part in 8,773,585 and 9,270,833 parts of water. The following results were obtained by varying the kind of negative metal :—- Table XIX.—Zn + Au + Chlorine in 13,950 grains of Water at £che, Grains. Volts. 0 -000026928 T0871 0 °000025344: 1°0228 0 :000024947 water ”? ? 376 On the Changes of Potential of Voltaic Couples. [June 21, The minimum proportion of chlorine in this case lay between 1 in 518,587,360 and 550,513,022 parts of water. Table XX.—Zn + Cd + Chlorine in 1550 grains of Water at 11°C. Grains. Volts. Grains. Volts. 0°3565 0 :2687 0 ‘02027 0 °32032 0 -05592 0°2831 water A 0°02796 0 3088 ‘ 5° Hleven other solutions of different strengths, all weaker than 002027, each gave the same potential as water. The minimum pro- portion of chlorine required to disturb the balance lay between 1 part in 55,436 and 76,467 parts of water. In this case, the addition of chlorine decreased the electromotive force; a similar effect occurred with a zinc-platinum couple in a solution of potassic iodide (‘‘ Influence of the Chemical Energy of Electrolytes, &c.,” ‘Roy. Soc. Proc.,’ June 7, 1888). The following are the minimum proportions of chlorine which were required to change the potential :— Table X XI. With an Astatic Galvanometer. Me + Pt + Cl. Between 1 in 17,000,000,000 and 17,612,000,000 Zn + Pt + Cl. <6 1 ,, 1,264,000,000 ,, 1,300,000,000 Zn + Au+ Cl. sf eee 518,587,360 ,, 590,513,022 Cd + Pt + Cl. ‘5 dare 8,733,900 955 9,270,833 ne oe Sle coe fons 55,436, 76,467 “ With a Reflecting Galvanometer. Mg + Pt + Cl. Between 1 in 27,062 millions and 32,291 millions. The examples contained in this paper are sufficient to show, that the proportion of the same exciting liquid, necessary to disturb the potential of a voltaic couple in water, and the order of variation of potential caused by change of strength of liquid, vary with each different positive or negative* metal. The numbers in Tables IV, VIII, XII and XXI, show that the more positive or more easily corroded the positive metal, or the more negative and less easily corroded the negative one, the smaller usually was the proportion of dissolved sibstance required to change the potential. In the case of chlorine, * Tf the negative metal is not at all corroded, the order of change of potential by change of negative metal is not much af.ected. i vig - YF 1888. ] | Magnetic Qualities of Nickel. 377 as well as in that of bromine, the magnitudes of the minimum pro- portions of substance necessary to change the potential of magnesium- platinum, zinc-platinum, and cadmium-platinum couples, varied directly as the atomic weights of the positive metals. The experiments also show that the degree of sensitiveness of the arrangement for detecting the minimum-point of change of poten- tial depends largely upon the kind of galvanometer employed. Asa more sensitive galvanometer enables us to detect a change of potential caused by a much smaller proportion of material; and as the propor- tion of substance capable of detection is smaller the greater the free chemical energy of each of the uniting bodies, it is probable that the electromotive force really begins to increase with the very smallest addition of the substance, and might be detected if our means of detection were sufficiently sensitive or the free chemical energy was sufficiently strong. VII. “Magnetic Qualities of Nickel (Supplementary Paper).” By J. A. Ewrne, F.R.S., Professor of Engineering in Univer- sity College, Dundee. Received June 14, 18388. (Abstract.) The paper is a supplement to one with the same title by Professor Ewing and Mr. G. C. Cowan, which was read at a recent meeting of the Society. It describes experiments, conducted under the author’s direction by two of his students, Mr..W. Low and Mr. D. Low, on the effects of longitudinal compression on the magnetic permeability and retentiveness of nickel. The resultsare exhibited by means of curves, showing the relation which was determined between the intensity of magnetisation of the metal and the magnetising force, when a nickel bar, reduced to approximate endlessness by a massive iron yoke which formed a magnetic connexion between its ends, was magnetised under more or less stress of longitudinal compression. Corresponding curves show the relation of residual magnetism to magnetising force, for various amounts of stress; and others are drawn to show the relation of magnetic permeability to magnetic induction. Initial values of the permeability, under very feeble magnetising forces, were also deter- mined. The experiments were concluded by an examination of the behaviour of nickelin magnetic fields of great strength. Magnetising forces ranging from 3000 to 13,000 c.g.s. units were applied by - placing a short bobbin with a narrow neck made of nickel between the poles of a large electromagnet, and it was found that these produced a practically constant intensity of magnetisation which is to be accepted as the saturation value. 378 Evaporation and Dissociation. Chlorophyll. [June 21, VIII. “Evaporation and Dissociation. Part VIII. A Study of the Thermal Properties of Propyl Alcohol.” By Wiiu1AMm Ramsay, Ph.D., F.2.S., and SypnEY Youne, D.Sc. Re- ceived June 14, 1888. (Abstract. ) In continuation of our investigations of the thermal properties of pure liquids, we have now determined the vapour-pressures, vapour- densities, and expansion in the liquid and gaseous states of propyl alcohol, and from these results we have calculated the heats of vapo- risation at definite temperatures. The compressibility of the liquid has also been measured. The range of temperature is from 5° to 280° C., and the range of pressure from 5 mm. to 56,000 mm. The memoir contains an account of the purification of the propyl alcohol; determinations of its specific gravity at 0°, and at 10°72; and of the constants mentioned above. The approximate critical temperature of propyl alcohol is 263°°7; the approximate critical pressure is 38,120 mm., and the approximate volume of one gram is 3°6c.c. The first two of these constants must be very nearly correct; the third cannot be determined with the same degree of precision. The memoir is accompanied by plates, showing the relations of volume, temperature, and pressure in a graphic form. IX. “ Contributions to the Chemistry of Chlorophyll. No. III.” By EDWARD SCHUNCK, F.R.S. Received June 19, 1888. (A bstract.) This paper is a continuation of the previous ones on the same subject. In it the author gives an account of the action of alkalis on phyllocyanin so far as regards the first stage of the process, and of the products thereby formed. Phyllocyanin when acted upon by alkalis yields in the first instance a well-crystallised substance of a peacock- or steel-blue colour, to which he gives the name of Phyllo- taonin. He describes its properties and those of some of its com-— pounds. When hydrochloric acid gas in excess is passed through a solution of chlorophyll in alcoholic soda, a compound erystallising in lustrous purple needles is formed, which seems to be the ethyl ether of phyllotaonin. By substituting methylic for ethylic alcohol a very similar compound is obtained, which the author considers to be the corresponding methyl ether. Though these compounds readily yield phyllotaonin by saponification with alcoholic potash or soda, the author did not succeed in reproducing them by the combined action of alcohol and hydrochloric acid on phyllotaonin. 1888. ] On the Specifie Resistance of Mercury. 379 X. “On the Specific Resistance of Mercury.” By R. T. GLAZE- BROOK, M.A., F.R.S., Fellow of Trinity College, and T. C. FITZPATRICK, B.A., Fellow of Christ’s College, Demonstrators in the Cavendish Laboratory, Cambridge. Received June 19, 1888. (Abstract.) The paper contains an account of experiments made to determine the value of the resistance of a column of mercury, 1 metre long and 1 sq. mm. in cross section, in terms of the B.A. unit. The method employed differed very slightly from that of Lord Rayleigh and Mrs. Sidgwick (‘Phil. Trans.,’ 1883). Tubes of about 1, 2, and 3 Sq. mm. in cross section were calibrated and filled with mercury. They were then immersed in melting ice, and their resistance com- pared with that of the B.A. standards, using Carey Foster’s method and the B.A. bridge. The length of the mercury column, occupying nearly the whole of the tube, was measured, and the mass of the same determined. From this the average cross section is obtained, and hence the value of r, the resistance of a column 1 metre long, 1 sq. mm. in cross section. The mercury used to find the cross section was with few exceptions that which had been employed in finding the resistance. The results of the measurements are given in Table I. In the table, Column 1 gives the number of the tube, Column 2 the number of the observation. L is the length of the tube, and a the mean radius of the cross section, R the observed resistance in B.A. units. The mean value of r found from the three 1 mm. tubes is 0°95354 B.A. units. The other four tubes of one-half and one-third units respectively lead to the value r = 0°95344 B.A. units. The difference between the two is considerable, and reasons are given for assigning more weight to the first value. For an account of the experiments and of the small precautions necessary to secure accuracy, reference must be made to the paper. Table II gives a list of the various values which have been found for r with the lengths of the column of mercury which, according to the different observers, has a resistance of 1 ohm (10° C.G.S. units of resistance). In combining our own observations we have assigned weights to the various tubes inversely proportional to their diameters, and we find as our final value ¢ = 0°95352. VOL. XLIV. oF =) GN 3 19 . , 12826-0 les pobeatid oo ea AS os, I GPhEs6- 0 PS86ZE-0 8960-0 G94. 1OT ft III = aie 9PESG- 0 PLOZES -O Z ” "g eet . BPERS- © ShES6-0 Eases. 0 S160: 0 GL. 16 ie tei ge ee oe ’ €hSS6-0 €E800¢- 0 i “ a > pace 0 PPES6-0 888008: 0 0280-0 €16-O1T ae OR ays 8 tae = S (GG (3 & ZPES6: O CIZ66P-0 S ePer:D PEE: 0 EEZ66P- 0 6280. 0 096-211 6, ae eee | es 9FES6-0 SO8TTO. T ‘ lig 9686-0 OT8110-T - "g S BP EFONQ OFES6- 0 GOSTIO: T a “ % 8 ECES6- 0 9Z6110- T €S¢0- 0 706 - TOT 1 eee wee es 2 % 19€S6- 0 960000. T a ‘ ‘L : RS LS8S6- 0 0F0000.T ‘ : Gg s PEGG. O E6866. 0 966666. 0 . : "g —~ 6PES6- O €01000- T ? - % , S 19896. 0 €€1000- T 2390: 0 S&P -LZT T BP eee GI cay ¢¢ (59 09896. 0 GC6666. 0 zs) aS LG8S6.0 286666 -0 is ° 9 Ss 188°6-0 TSeS6- 0 G16666-0 us < "g Ss e66c6.0 6P6666- 0 y * "g P9IES6- O 66666. 0 2 e iz SSeS6- 0 010000. T 980-0 Fel: €11 I a eee aN ‘aqny Tove Wort : : : ; : : A jo onTGA UvoT S a a T eqn JO oN =) 6 T P19°L 1888. ] On the Structure, §c¢., of Fossil Reptilia. 381 Table II. Value of Value for r ohm in Observer. Date. in B.A. centimetres units. | of mercury ? at 0°. Lord Rayleigh and Mrs. Sidgwick.... 1883 0:95412 106 °23 Mascart, Nerville, and Benoit........ 1884 '0:°95374 106 °33 ECORI Gales. adobtle idl. dele ss 1885 0 -95334 ree POE AD Ze Ses oh cleuyorsyd © Syehe-cae sao; eyo-aie ie 1885 0 °95388 105 °93 beri ewa racecars: ccc a kesie seus ee vans 1887 0°95349 106 -32 meommramsen Veer ses S.A Ie, 1888 0°95331 106 °32 Glazebrook and Fitzpatrick.......... 1888 0 °95352 106 °29 _ The paper contains a discussion of the above results. It is shown that probably Lord Rayleigh’s value of r may be too high by as much as 0°0002, in consequence of the fact that the mercury in his terminal cups was 5° or 6°C., but no complete explanation of the differences between his result and those of Rowland, Koblrausch, and ourselves, has been found. ‘The difficulty of working with tubes such as those used by the Lorentz, 1—2 metres in length, and 1, 2, and 3 cm. in diameter, may perhaps account for his value for the ohm, viz., 105:93. ‘XI. “ Researches on the Structure, Organisation, and Classifica- | tion of the Fossil Reptilia. VI. On the Anomodont Reptilia and. their Allies.” By H. G. SEELEY, F.R.S. Received June 20, 1888. (Abstract. ) The author examines the structure of the skull in the Dicynodontia, and discusses the interpretations of its elements and affinities given by Sir Richard Owen, Professor Huxley, and Professor Cope, and arrives at the conclusion that the interpretation of the bones of the palate may be varied. The quadrate bone is found, though it is: absent from many specimens owing to loose articulation, and the malleus is recognised as a normal element in the skull, which articulates with the quadrate and is free, except at its extremities. The palatine bones are internal to the pterygoids, and the ptery- goids extend forward to the maxillary. The columella is found ‘im more than one specimen. Many new specimens are described which further elucidate the structure of the skull. The first of these shows that the upper part of the foramen magnum is formed 22 382 On the Structure, §c., of Fossil Reptilia. [June 21, by the supra-occipital bone, and that the element which has appeared to be a supra-occipital is the inter-parietal. Evidence is given of the form of the brain case, which is found to be’ high and narrow. Details are given of the structure of the squamosal bone, and of its relation to the quadrate and other cranial elements; and it appears that the squamosal usually embraces the quadrate, so as to extend in front of it, and sometimes to hide it, so that both the quadrate and squamosal sometimes contribute to form the articulation for the lower jaw. Hvidence. is offered of the sutures which divide the bones of the skull from each other. The sub-nasal element, found in Pareiasaurus, is met with in Dicynodonts, sometimes below the narine, and sometimes within its floor in the position of a turbinal. A new type of quadrate bone, which is regarded as Anomodont, is described, and found to differ from the usual form in being perforated in the antero-posterior direction. A summary of the structure of the skull is Ulustrated by a restoration showing its sutures. Further contributions are made to a knowledge of the vertebral column. The cervical vertebre are described, the atlas and axis are regarded as anchylosed, and succeeded by an intercentrum which has no neural arch. The cervical ribs are comparatively long, and articulate by a long fork with the neural arch, as well as with the centrum. Further evidence is given of the structure of dorsal vertebrae, showing that the rib is attached to a single transverse process of the neural arch. The caudal vertebre of Platypodosaurus, eleven in number as preserved, are described; and some observations are made on the mode of ossification of the intervertebral substance. Additional materials further elucidate the Anomodont scapular arch, and examples of scapula and coracoid are described; but the only additional pelvic bone described is the pubis of Titanosuchus. An account is given of the limb bones, which are elucidated by large bones associated with the skull fragments described by Sir R. Owen as Titanosuchus ferox. They contribute to a knowledge of the femur, humerus, and fibula in that type, and are associated with small bones of the extremities which are probably metacarpals. The ulna is described, which was referred by Sir R. Owen to Pareiasaurus, and evidence is given that it possessed terminal epiphyses of different ' form to any which are known in fossil reptiles, the proximal epiphysis having much the character of the olecranon of a mammal. A massive Anomodont tibia, also referred by Sir R. Owen to Pareiasaurus, is described, and found to possess a distal talon of mammalian pattern. Further observations are made upon the Theriodontia, as restricted to the genus Galesaurus, the skull of which is further elucidated. The author also describes new material, making known the structure of the skull, palate, and scapular arch of Procolophon; from which it appears that the pre-coracoid is exceptionally well developed, and ai — -1888.] A new Form of Eudiometer. 383: united by suture to the coracoid. The inter-clavicle had the slender T-shaped form of the bone in Ichthyosaurus. Procolophon has teeth on the vomera and pterygoid bones, and the structure of the palate and the post-orbital region show that the Procolophonia forms a distinct division of the Anomodontia. Obser- vations are made on the relations of the European and South African Anomodonts, and on the relation of the Anomodontia to the Pelyco- sauria and to Cotylosauria. Comparison is made with Placodus, which genus has two exoccipital condyles, comparable to those oi mammals, and appears to have lost the basi-occipital condyle. Com- parisons are made with other extinct reptilia to show the relation of the Anomodonts to the Saurischia, and other reptilian types. Obser- vations are offered on the theory of the Anomodont skull, and on the effect of the articulation of the lower jaw with the squamosal in causing a diminished growth of the malleus and quadrate, converting them into the malleus and tympanic. The larger groups included in the Anomodont alliance are regarded as the Pareiasauria and Procolophonia; Dicynodontia, Gennetotheria, and Pelycosauria; the Theriodontia, Cotylosauria, and Placodontia are regarded as coming under the same sub-class, which at one end of the series exhibits characters which link reptiles with amphibians, and at the other end of the series link reptiles with mammals. XII. “A new Form of Eudiometer.” By WILuiAM MARCET, M.D., F.R.S. Received June 20, 1888. [Puate 14.] The quantitative determination of oxygen, simple as it appears at first sight, is found in practice beset with many difficulties. Liebig’s method with pyrogallic acid and potassium hydrate, though con- sidered as yielding correct results, takes too much time, and is un- satisfactory in some respects, so that the eudiometer has become ot general use for the estimation of oxygen. I shall not attempt to describe the various forms of eudiometer, but it may be assumed that _ Regnault, so well known for the care he bestowed on his investiga- tions, had adopted a very correct kind of eudiomeier in the researches he undertook with Reiset on the chemical phenomena of respiration.* Other eudiometers have been made since then, such as the ingenious instrument of Dr. Frankland for gas analysis, which has proved most serviceable. I claim for the present form of endiometer that it is - correct and reliable in its working, simple in construction, and easy of manipulation. The main objects of an eudiometer must be the easy introduction of the air to be analysed, the ready mixture of that air with a known volume of pure hydrogen gas, and the correct reading * ‘Annales de Chimie et de Physique,’ 3rd Series, vol. 26, 1849. 384 ~ “Dr. W. Marcet. | [June 21, of the volume after explosion. It will be seen that these conditions are entirely fulfilled in the present instrument ; and it has, moreover, the advantage of being available in conjunction with Pettenkofer’s method for the determination of carbonic acid in atmospheric air. The eudiometer as figured in the accompanying Plate has the form of a TJ -piece, the vertical limb of which is a straight tube about 60 cm. in length and 12 cm. in diameter ; it is divided into 50 or 60 c.e. and tenths of ¢.c., ike a common burette. The upper end of this tube is closed air-tight with a steel cap, from which lateral tubes project right and left; these tubes are bent \/-shaped, or rather in the form of a lyre. At the junction of the lateral tubes with the cap, there is a three-way stop-cock allowing of the passage of air or gas in four different directions, viz., first through the tubes cut off from the body of the eudiometer ; secondly, into the eudiometer, which is done by raising it in the mercury trough; thirdly, out of the eudio- meter, on the side opposite that from which it was introduced, which is effected by depressing the tube in the mercury; fourthly, through the tubes and eudiometer simultaneously. The eudiometer is held tightly by two claws projecting at different heights from a vertical iron rod connected with a rack and pinion movement. The iron rod, together with the eudiometer, is immersed in mercury contained in a straight cylindrical glass vessel. The hydrogen used for the explosion is prepared for that special object from zinc and sulphuric acid in the ordinary way, and washed through an alkaline solution, rather than obtained condensed in iron bottles from the manufacturers, and it is collected in a bell-jar suspended over water. The bell-jar I use holds 11 litres of gas; it is balanced by a counterpoise, and its weight, as it moves up and down in water, is regulated by another counterpoise hanging from a cycloid, so that the gas in the holder is always under atmospheric pressure ; an oil-gauge fixed to the holder shows at any time the pressure in the bell-jar. Should the gas fail to be absolutely under atmospheric pressure, the equality of pressures may be ensured by the use of the adjusting instrument I have described in a former communication. It consists of a clamp fixed to the rim of the tank, and made to grasp at will the cord holding the counterpoise; a screw in connexion with the clamp enables the cord, and consequently the bell-jar, to be drawn up or down. For the actual requirements of the analysis, a receiver for the hydrogen holding only one litre of gas would suffice, but it 1s better to have a larger gas-holder in which to store up the hydrogen for future determinations. Moreover, the cycloid arrangement for regulating the weight of the bell-jar, though very convenient, may be dispensed with, as the gas in the receiver can be brought approximately under atmospheric pressure -> 1888. ] A new Form of Eudiometer. 38D) by means of weights, while the adjusting screw will enable its being accurately placed under atmospheric pressure. The analysis is made as follows :— We suppose that air for analysis has been shaken with barium hydrate in a glass jar of a capacity of about 10 litres, and made according to the form adopted by Dr. Angus Smith* for the determination of carbonic acid in air by Pettenkofer’s method. This jar is closed by a tight-fitting india-rubber cap, which I cover with several coats of copal varnish; from this cap two short india-rubber tubes project, each of these tubes being clamped by a pinch-cock. After the agitation is over, and when all the carbonic acid is taken up by the alkaline solution, the fluid is poured out from the jar into a glass-stoppered bottle holding about 100 ¢.c. This can be done easily without letting any air into the jar, as the india-rubber cap will collapse somewhat while the fluid is allowed to run out through one of the india-rubber tubes in the cap, a very small quantity of fluid only being left in the jar. The india-rubber tube is again clamped, and the bottle holding the barium hydrate is sealed with parafiine and left undisturbed for the precipitation of the carbonate and subsequent analysis. The glass jar full of air free from carbonic acid, and absolutely saturated with moisture, is placed under a funnel supported on a filter stand, and the funnel is connected with one of the india-rnbber tubes projecting from the cap, while the other tube has a short piece of glass tubing inserted into it, to which a longer india-rubber tube is _ fixed. _ Everything is now ready for the determination of the oxygen of the air contained in the glass jar. After turning the stop-cock in the cap of the eudiometer, so as to allow the hydrogen gas to wash out the steel tubes and top of the eudiometer, the latter is lowered in the eylinder until the mercury is in contact with the cap, and therefore very near to the stop-cock. The eudiometer is next connected by narrow india-rubber tubing with the hydrogen receiver on which a weight has been placed, and on opening the receiver hydrogen rushes out, washing thoroughly the passage through which it will have to reach the eudiometer, and driving out the very small quantity of air contained in the steel cap between the mercury and the stop-cock. [ found it convenient to stop the end of the \/-shaped tube letting out the gas with short india-rubber tubing and a pinch-cock. When a few hundred cubic centimetres of gas have gone through, the three-way tap is turned by one-quarter of a turn, so as to place the tube in communication with the hydrogen ; it is now easy to rinse the eudio- meter with that gas, by raising the eudiometer, and then giving the three-way cock half a turn, so as to bring the instrument in communi- * ‘ Air and Rain,’ 1872. 386 Dr. W. Marcet. [June 21, cation with the external air; the eudiometer is then rapidly depressed and closed. In this position the tube from the hydrogen can be rinsed again, independently of the eudiometer, so that the washing may be considered as complete and thorough. The eudiometer being brought into connexion with the hydrogen is again raised, and 18 c.c. of hydrogen gas are taken in under atmo- spheric pressure. The hydrogen kept over water is saturated, and a thermometer with its bulb in the bell-jar gives the temperature of the gas, which is very nearly that of the laboratory; so that by the time the gas is ready to be measured in the eudiometer it shows no tendency either to contract or dilate. The eudiometer now contains the. volume of hydrogen required for the analysis, and the stop-cock is turned shutting off the gas from the holder, and opening the \/- shaped tubes through and through in readiness for washing out with the air to be analysed. The air from the large glass jar is introduced into the eudiometer in the followmg way. Having filled the funnel referred to above with water, the latter is let into the jar by opening slightly the pinch-cock closing the funnel; at the same time the glass jar having been connected with the \f/-shaped tube of the eudiometer by india- ° rubber tubing, is opened towards the imstrument, when the air displaced by the water added rinses out the india-rubber and steel tubings. There is plenty of air in the jar, so that no necessity occurs to be saving; when the tubes are rinsed the eudiometer is raised in the mercury up to about 40 c.c., carrying a column of mercury with it; then the two-way stop-cock is very carefully turned so as to admit the air to be analysed, which is aspired by the mercury as it subsides. Thus some 27 c.c. of air are introduced. The aspiration must be fairly rapid, and the fall of mercury in the tube should be stopped by turning the stop-cock before the mercury has quite reached its level in the trough, otherwise there is a risk of a recoil of the mercury, and a “pumping ’”’ which it is important to avoid. The inixed gases are left undisturbed for two or three minutes, and their volume is read off under atmospheric pressure, the eudiometer being next moved up and down in the mercury by a few centimetres, so as to effect the perfect mixture of the gases. The instrument is now shghtly raised, carrying with it a short column of mercury, and the gases are ignited by the electric spark under reduced atmospheric pressure. This mode of proceeding, recommended by Mcleod,* weakens considerably the violence of the explosion, and ensures per- fect safety. Immediately after the explosion the gas in the eudio- meter is brought approximately under atmospheric pressure. * McLeod, “On « new Form of Apparatus for Gas Analysis,” ‘Chem. Soe: Journ., ’ 1869. Proc. Rey. Soc. Vol.44.PL.14 Find Ble™ no uh QUT f 2 AS Se 2 eee ene ena ty) (ven cs gees gk Ny na es i a ee ee te eee = | = eS SE Se Se ae ae —_ naomi ano dois t ; I} | [ ie i —_—_ eer | riccciee Ro gig eee cl WENO } . Stop cock Letting gases urto & through Af the Budiometer uv 4 different ways. West,Newman&C?lith # 1888. | A new Form of Eudiometer. 387 A slow contraction now takes place as the heat produced by the explosion is radiated from the instrument; it is advisable to wait about twenty minutes, until the contraction is complete, and the volume of the gas is read off under atmospheric pressure. The instrument shculd be sheltered from any draught, or from the direct radiation of a fire, and indeed be kept from any change of temperature, and with that object I find it advisable to shelter it with a cardboard tubular shield sliding up and down the mercury trough. If air taken directly from the atmosphere is to be analysed, in order to ensure its being saturated it will be advisable to pass it through a tube full of wet horse-hair, and obtain it directly from the tube into the eudiometer. In the above account of the manipulation required, the hydrogen is introduced before the air into the eudiometer. I have tried to let in the air first, but this plan was not successful apparently because the mixture of air and hydrogen was incomplete before the explosion. The hydrogen being collected first in the eudiometer will rise from its comparative lightness as the air is drawn in and mix with it perfectly, while the stream is sufficiently rapid to prevent any of the mixture from diffusing out of the tube. It should be borne in mind that after a number of analyses the water resulting from the explosions accumulates on the surface of the mercury in the eudiometer, and the mercury meniscus is no longer clearly seen. This can be easily avoided: by drying the tube with filtering paper after a certain number of analyses. The following are a few determinations of oxygen in atmospheric air made with the form of eudiometer described above. They are not selected, but given in succession in the order in which they were made. And I must here beg to record the valuable aid of my assistant, Mr. Charles F. Townsend, F.C.S., in the present inquiry. Oxygen per cent. in Atmospheric Air. First Series. Second Series.* 21-01 20 94 20°98 20 :93 21°00 20 -96 +20. °97 20 °95 20 97 20 OS 20 95 Mean .. 20°99 20 96 Greatest difference, 0 ‘2 per cent. Mean... 20 °946 Greatest difference, 0 ‘14 per cent. * One analysis omitted: obviously too high from insufficient rinsing. 388 Mr. W. H. L. Russell. — [June 21, XIII. “ Theorems in Analytical Geometry.” By W. H. L. RUSSELL, F.R.S. Received June 21, 1888. To determine the envelope of the first polar of any curve, when the pole moves on a given curve of the third order. Let F (&, 7, €) = 0 be equation to the surface; then if p = q= =,” = ie pu + qy +rz = 0 is the equation to first polar, when (v, y, 2) moves on a given cubic, e+ y2 + 22+ 6mayz = 0. Then differentiating (a? + 2myz) dx + (y® + 2maz) dy + (2 + 2may) dz = 0. pdx + qdy + rdz = 0. Then as usual 2% +2myz = rp, y2 + 2maz = gq, z+ 2may = Xr. Then eliminating z by the equation to the first polar, we have— Az*, +); Bry; 4+ Gy? = 9, Da? + Exy + Fy? = q, Ga?,+ Hay + Ky? = +, where A, B OG... . are fun tions of pgr, whose forms are imme- diately seen, and the arbitrar, multiplier is omitted because it will disappear in the final result: then we find at once the values of a”, wy and so z*, y*, and therefore of a, y, z, which we may substitute in the equation to the polar, and so obtain the envelope. But we may find a more symmetrical result thus: eliminating as before by means of the equation to the polar— | A’'y? + Blryz+.C'2 = p, D’y? + Hyz + F'2 q; Gy? + HWyz+K'2 =71; and moreover ~—-1888.] Theorems in Analytical Geometry. 389 Al'Z + Bez + O's? = p, D's? + Evaz + Fa? = g, Ge Boas + K's = *. Hence the equation to the envelope is— oe { p(EK — HF) + q(HC — BK) +7(BF — EC) \ ~ *\ A(EA — HF) + DIC — BK) + GBF — EC) n { p(H'K’ — HF’) + ¢(H’C’ — BK’) + (BE — EC) i 7 AK — HF) + D(HO'— BK) + G(BF — EC) + ‘ p(B"K" hi AE") = q(H’’C" raw BK) ze r(B"F” zie Ak O40) \ a Ae") DC" — BK") + GB "EO" When the curve Fis of the third order the first polar becomes a eurve of the second order, which is called the polar conic. Let us see what curve the pole must move on for the polar conic to break up into two straight lines. Let— E (@? + 2myz) + (y® + 2mez) + € (2 + 2may) = or the equation to the polar conic. Then x + Amex (e + =) + (iy + 2myz + <2) er and that this equation may break up into factors must be a square; or ua - ©) 2+ Wm (OS 4 sf) 2+ (“5 - FY y must be a square; or F-DCE-2) =~ (CE -3) or —m(8 + 7 + 8) + (14+ 2m )Eqe = 0, the equation to the Hessian. Hence the equation to the straight lines is of the form— z+m a Et ae) = gh 390 Mr. W. H. L. Russell. [June 21, and therefore the line Ea + myz + mty = 0 must pass through the point of their intersection. So also must ny + moa + mee = 0, fx + mau + mey = 0. The pole and the intersection of these two straight lines are called by Dr. Salmon corresponding points. When I had proceeded thus far, and had begun to make deductions from these equations, I became acquainted with the existence of a memoir by Professor Cayley on this subject in the ‘Phil. Trans.’ for 1857. He has there given these equations without proof. I have therefore demonstrated them exactly in the way in which I discovered them before I was acquainted with his paper, to which I refer for ulterior theorems. To determine the double tangents of a quartic. Let y = ma +a be the equation to a straight line cutting the quartic. If this value of y be substituted in the quartic, the equation will become e* — Pa +Qc?— Rae +S = 0, so that if a, 8, y, 6 be the roots of this equation, we have the following equations :— atB+y+6 =P, aB + ay + ad + By + BO+ 46 = Q, aBy + ay + afd + Bys = R, apys = 8. Then for the bitangenitsa = 6B, y = 64, 2(a+y) = Os a? + day + y? = 2ay (2 +7) = R, apyo = ay? = § Gta? +%y=Q o a =o P2 R P(e yl Re eee € x) Hy, 2) She R2 and therefore B= S. 1888. | Theorems in Analytical Geometry. 391 _ By means of the two equations— (glee Ws cue Pig 3) =® Py at since P, Q, R, S are functions of m and a, we determine the double tangents. We may also use the above equations to determine the two tan- gentials of any single tangent of a quartic in the point where the tangent meets the curve again. In this case we assume ™, a, a as . known, and we have— 22 +7 +6=P, eo cay ead ye = "OQ from which the co-ordinates of the tangentials may be determined by the solution of a quadratic equation. We next proceed to find the equations which determine the bitan- gents of the quintic. We substitute y = mx +a in the general equation, and obtain (using the same notation)— atBt+tytotp=P, ap + ay + ad + ap + By + BO + But yo t+ y+ cu = Q, aBy + aB0 + aBp + ayo + aye + adm + Byd + Byw + Bow + you = RK, ays + aByw + aBdp + aydu + Bydu = SB, apyou = T. Puta = B, y = 4, then the equations become— Aa+y) +p = P, a+ y+ 2(at+ty) et 4ay = Q, Qary + Qary? + (a + 97) w+ Aare ~ ay? + Qay(at-q)e = 8, ae = T. B= Hence aty = aa (atytpe)? + 2ey = Q+ 2p’, Pp? iy Bu Sa Rocretagiimemy ss haragh Hence the remaining equations become— a 392 Capt. W. de W. Abney and Dr. T. E. Thorpe. [June 21, (0-5-9449) Cr) 1 > Pa. SPY P2 Pa . dp*\ (P — “) ” ENF bag Sern a) Bu? (9-2 "hs We have to eliminate » between these three equations; the re- sultant between equations of the third and fourth order is given by Salmon; also the resultant between two quartics, from which we may deduce the resultant of a quartic and a quintic. The result will be tremendously complicated; but we must remember the number of double tangents to a non-singular quintic is 120, which naturally suggests an equation of the 120th degree, which I apprehend few mathematicians would like to solve. It is impossible, however, to predict the future of analysis. I have omitted to take any notice in this paper of the modifications which would be occasioned by double points, hoping, if permitted, to return to the subject. I would observe in conclusion that the same method applies to the determination of points of inflexion. Thus in the quartic, taking a, 8, (, 6 for the roots of the equation produced by eliminating between the quartic and a straight line, and putting a = B = 4, we find it easy to eliminate a and 6 and to find two equations which will give the inflexional tangents. XIV. “On the Determination of the Photometric Intensity of the Coronal Light durmg the Solar Eclipse of August 28-29, 1886. Preliminary Notice.” By Captain W. DE W. ABNEY, C.B., R.E.,. F.R.S., and T. Gi Hepes eee Received June 21, 1888. Attempts to measure the brightness of the corona were made by Pickering in 1870, and by Langley and Smith, independently, in 1878, with the result of showing that the amount of emitted light as observed at various eclipses, may vary within comparatively wide limits. These observations have been discussed by Harkness (‘ Washington Observations for 1876,’ Appendix III), and they will be again discussed in the present paper. Combining the observations it appears that the total light of the corona in 1878 was 0°072 of that of a standard candle at 1 foot distance, or 3°8 times that of the full moon, or 0°00C0069 that of the sun. It further appears from the photographs that the coronal light varied inversely as the square of 1888.] Jntensity of Coronal Light during Solar Eclipse. 393 the distance from the sun’s limb. Probably the brightest part of the corona was about 15 times brighter than the surface of the full moon, or 37,000 times fainter than the surface of the sun. The instruments employed by the authors in the measurement of the coronal light on the occasion of the solar eclipse of August 28-29, 1886, were three in number. The first was constructed to measure the comparative brightness of the corona at different distances from the moon’s limb. The second was designed to measure the total brightness of the corona, excluding as far as possible the sky effect. The third was intended to measure the brightness of the sky in the direction of the eclipsed sun. In all three methods the principle of the Bunsen photometric method was adopted, and in each the com- parison-light was a small glow-lamp previously standardised by a method already described by one of the authors in conjunction with General Festing. In the first two methods the photometer-screen was fixed, the intensity of the comparison-light being adjusted by one of Varley’s carbon resistances: in the third the glow-lamp was main- tained at a constant brightness, the position of the screen being adjusted along a graduated photometer bar, as in the ordinary Bunsen method. Full details of the construction of the several pieces of apparatus will be given in the full paper. | The observations during the eclipse were made at Hog Island— a small islet at the south end of Grenada, in lat. 12° 0’ N. and long. 61° 43' 45” W., with the assistanee of Captain Archer and Lieutenants Douglas and Bairnsfather of H.M.S. “ Fantome.” The duration of totality at the place of observation was about 230 seconds, but _ measurements were possible only during 160 seconds, at the expira- tion of which time the corona was clouded over. A careful discus- sion of the three sets of measurements renders it almost certain that the corona was partially obscured by haze during the last 100 seconds that it was actually visible. Selecting the observations made during the first minute, which are perfectly concordant, the authors obtain six measurements of the photometric intensity of the coronal light at varying distances from the sun’s limb, from which they are able to deduce a first approximation to the law which connects the intensity of the light with the distance from the limb. The observations with the integrating apparatus made inde- pendently by Lieutenants Douglas and Bairnsfather, agree very closely. It appears from their measurements that the total light of the corona in the 1886 eclipse was— Douglas vis Ut Vis 0 ‘0123 standard candle. Bairnsfather .......... 0 -0125 4; Mea nj vindh -«« 0 0124 at a distance of 1 foot. 394 Prof. J. A. Ewing. Seismometric Measurements [June 21, In comparing these observations with those made during the 1878 eclipse, it must be remembered that the conditions of observation on the two occasions were widely different. The observations in the West Indies were made at the sea’s level, in a perfectly humid atmo- sphere and with the sun at no greater altitude than 19°. Professor Langley, in 1878, observed from the summit of Pike’s Peak in the Rocky Mountains at an altitude of 14,000 feet, in a relatively dry atmosphere and with the sun at an altitude of 39°. From observations on the transmission of sunlight through the earth’s atmosphere (Abney, ‘ Phil. Trans.,’ A, vol. 178 (1887), p. 251) one of the authors has developed the law of the extinction of light, and, by applying the necessary factors, it is found that the intensity of the light during the 1886 eclipse, as observed at Grenada, is almost exactly half of that of which would have been transmitted from a corona of the same intrinsic brightness when observed at Pike’s Peak. Hence to make the observations of Professor Langley comparable with those of the authors, the numbers denoting the photometric intensity of the corona in 1878 must be halved. The result appears, therefore, that whereas in 1878 the brightness of the corona was 00305 of a standard candle at a distance of 1 foot, in 1886 it was only 0:0124 of a candle at the same distance. Several of the observers of the West Indian Eclipse (including one of the authors) were also present at the eclipse of 1878, and they concur in the opinion that the darkness during the 1886 eclipse was very much greater than in that of 1878. The graduations on instruments, chronometer faces, &c., which were easily read in 1878, were barely visible in 1886. In explanation of this difference in luminous intensity it must not be forgotten that the 1878 eclipse was not very far removed from a period of maximum disturbance, whereas in 1886 we were approaching a period of minimum disturbance. XV. “Seismometric Measurements of the Vibration of the New Tay Bridge during the Passing of Railway Trains.” By J. A. Ewine, B.Sc., F.R.S., Professor of Engineering in University College, Dundee. Received June 20, 1888. The absolute methods of seismometry which have been developed during recent years in Japan, and have been applied to the measure- ment of earthquakes there and elsewhere, may serve a useful purpose in determining the extent and manner of the shaking to which engineering structures are subject through storms of wind, moving loads, or other causes of disturbance. Existing forms of seismograph are well suited for measurements of this kind, provided the frequency oe ces > 1888. ] of the Vibration of the new Tay Bridge. 395 of the vibrations to be measured is neither very much greater nor very much less than is usual in earthquakes, and provided, of course, the amplitude of vibration does not exceed the capacity of the in- strument. For vibrations of high frequency a greater rigidity in the multiplying and recording apparatus would be necessary; in vibra- tions of very long period, on the other hand, the: mass whose inertia furnishes the steady-point of reference will not remain at rest. Between these extremes, however, there is a wide range within which such seismographs as are now used to measure earthquakes may be trusted to give a record that is correct in all substantial particulars, and the vibrations to be referred to below fall within this range. The writer has recently employed his Duplex Pendulum Seismo- graph to examine the vibration of the new Tay Bridge while railway trains are passing over it, facilities for this examination having been kindly given by Mr. Fletcher F. 8. Kelsey, resident representative of Messrs. Barlow, the engineers of the bridge. The results are per- haps worth publishing, not so much for any interest they have in themselves, as because they exemplify a novel method of inquiry which may prove of use in other cases to engineers. The duplex pendulum seismograph, which was designed for and applied to the measurement of earthquakes in Japan in 1882,* consists essentially of a pair of masses which are supported and connected in such a manner that they form an astatic combination with freedom to move in any horizontal direction. One of the two is hung from above and is stable; the other is supported from below and is unstable; and the two are constrained to move together by a ball-and-tube coupling. Their equilibrium is adjusted to be very nearly neutral, and this fits them to furnish a steady-point with respect to which motion of the ground in any azimuth may be recorded and measured. The motion is recorded by a lever, the marking point of which draws a magnified copy of the horizontal motion of the ground upon a smoked-glass plate. Fig. 1 shows the construction of the duplex pendulufii seis- mograph as used in these experiments, and as now made by the Cambridge Scientific Instrument Company for earthquake observa- tories. The stable mass is a disk of lead a cased in brass (shown in section in fig. 1) hung by three parallel wires from the top of the contain- ing box. This trifilar suspension has several advantages over the usual suspension of a pendulum from a single point; in particular it prevents twisting about a vertical axis. The unstable or inverted pendulum 6 is also a disk of lead below the other, and is held up by a tubular strut which ends in a hard steel point resting in an agate socket in the * See ‘Transactions of the Seismological Society of Japan,’ vol. 5, p. 89, or the author’s memoir on ‘“ Earthquake Measurement’’ (‘Memoirs of the Science Department of the University of Tokio,’ No. 9, 1883). VOL. XLIV. 2G 396 Prof. J. A. Ewing. Seismometric Measurements [June 21, = —— Sees A /_|TO TAL | JIN BeBe mari Zea Paes fee Sannane pe els Neale eeel b < 110 bk Na al erence HCE ae SS 421 Maxima and certain Conditions of Temperature, &c. 618 696 PIT PIL 88 18 LL-8 19-8 €o- 9 8h-9 09€ 68S ‘OTT IIL é8 82 GS-6 T&-8 88-¢ 94-0 19€ 193 PEL O&T 68 98 G0. oI $3-6 61-4 PE-G 6PP TE O9T SOT ZOE = LOT g6- LT L9- LT €9: OT €T- OT c6P ets LLT cst &3T 6éT 67-16 £8. SZ $8. &T 6S. 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OL LG. &T 6F- IT c&- 31 60P SPs T6T PEL SOT 90T 64-11 L6- 61 €9- OL 0€- IT PLE Loe SIT cOT 96 68 _ 66-0T LL-8 PE. 6 82-8 SPE 866 OTT ATT F6 OO. | 96-6 TS-6 68.4 GS-8 "sd0 "S40 *duio0g ‘sdO ‘dm0p ‘sao “duo ‘sao ‘duog ‘sa0 "180K GRA) OU Se ee ee ee oun fp *IBo "19q0J0Q 07 OuNL "189K | ‘19q0WO 0}.0unP -Aouonber 7 ‘(g x sanoyq) Aouonberq *(soyout) sorueuty *(soqysulIMoYyO) sivof ouo-fyueM4 UT ‘(exodipy) saved ueaes uy - “eqqgnorey ye Aqquengy) pue Aouonbesg |[eyUreyY Jo uoNVUIEA peuInTG "*"pim * 8a oe ad (74 ZS eis | eaten) | 7 ee a i cs 0Z 2 ae oo ee ''6L c< SL os “en “cc LI ee a 7 | sé 9T ee "OL (74 CL ee °C “6 PL oe "LT c¢ eL ee cle a4 uoo NT **toou * It es Aen a5 “ec OL +o UE ¥ 6 ee ‘ip (t4 ee ae (74 9 ee pit (74 G ee “9 “ec 7 ee "DT ce € oe aoe if z ee re ‘¢ T <) One “sitlO AL 429 Mr. H. F. Blanford. The Diurnal Barometric In the rainy season there were 2929 rainy hours in the seven years, giving an average of 122 for each hour of the day. But for the, hour. between 10 and 11 p.m. there were but 78 instances of rain, or but two-thirds of this average, and from 8 to 9 a.m. but 91 instances of rain, or three-fourths of the average. The deficiency in the quantity of the rainfall was even more striking. The average per hour of the day was 12°81 inches, but the recorded amount for the hour between 10 and 11 p.m. was only 4°76 inches, or less than two-fifths of the general average, and that from 9 to 10 a.m. was 8°46 inches, or little more than two-thirds. Another equally striking example of the approximate coincidence of interruptions of the rainfall, about the time of the diurnal maxima of pressure, is afforded by Batavia, on the evidence of ten years’ registers of the hourly rainfall, published by Dr. Bergsma in the 3rd volume of the ‘ Batavia Observations.’ Here also, it is only the rainy reason (December to January) that exhibits this feature in a very decisive manner, and the coincidence is the more remarkable, since, in another respect, the diurnal variation of the rainfall of Batavia stands in marked contrast to that of Calcutta. At Calcutta the greater proportion of the rain falls in the daytime; at Batavia at night. The percentages were respectively as follows :— Calcutta. Batavia. From 6a.Mto6p.M..... 60°3 per cent. 47°8 per cent. From’6 Pat. to GM. ey Woe Boe. And the Batavian maximum follows the minimum within four hours, in the proportion of 5 to 2. The following table gives the total rainfall in millimetres, recorded at each hour of the day of the three rainy months during the ten years 1866-1875 (Sunday excepted), and in a parallel column the smoothed values computed as in the former case. The curve, fig. 6, is drawn from these latter figures. Total Hourly Rainfall at Batavia (December to February), ten years. Hours. Observed. | Computed. Hours. | Observed. | Computed.|. mm. mm. mm. mm. Midn. to 1.. 571 550 Noon to 13... 364 374 1a ecteg a 584 547 13. ., 14,03 |e oaelees 413 2 ay tat Se 448 489 iF peeaal ba 413 403 Sieinag. 1A rs 478 451 1S: yy Ges 362 394 praesent...) Aol 452 16 «1%. 432 ee ihe oa 527 472 dL AR io 486 446 Ghee Map Tie 435 445 18. 319% 373 385 mee. ek)! Bae 401 19. .,; 20.01 yee 312 8 iy ews 404: 392 20 <5, Zhan 263 266 9 Seige.) 379 362 21 ,, 22. a) ee 308 i Melita de. i Sp 326 22 |, 23.001 508 431 1] 4, moan: 351 338 23 ,, midn. 475 507 Maxima and certain Conditions of Temperature, &c. 423 The general average of all the hours is 412 mm. per hour, but the quantity recorded between 9 and 10 p.m. is only 231 mm., or little more than half, and that between 10 and 11 a.m. 288 mm., or little more than three-fifths of this average. Itis to be observed that the forenoon minimum of Batavia falls an hour later than that of Calcutta, whereas the evening and principal minimum is an hour earlier. This is exactly what might be expected from the combina- tion of a double diurnal oscillation with one of single period, the latter having its maximum in the former case at night, in the latter in the daytime. The Melbourne hourly rainfall tables show great variations in different months, and admit of very little definite conclusion, except that, as at Batavia, there is more rain at night than in the day. It is then only in the warm and nearly saturated atmosphere of Bengal and Java, in their respective rainy seasons, that these diurnal inter- ruptions of the rainfall about the hours of the two barometric maxima are decidedly manifested. But in these two cases they are most marked; and this circumstance, taken in conjunction with the corresponding cloud variation, which is shown by so many stations, points strongly to a causal connexion between the diurnal variation of pressure and the condensation of atmospheric vapour in the cloud- forming strata of the atmosphere, which, I think, we can scarcely fail to recognise. The mere fact that an increase of atmospheric pressure, from what- ever cause arising, is accompanied with a dissipation of cloud and a diminution of rainfall, would not perhaps call for special remark. But it is to be observed that whereas the nocturnal barometric maxi- mum, at all the stations here dealt with, is less pronounced than that of the forenoon, the concomitant effects in the clearing of the atmo- sphere and in the check in the rainfall are much greater in the former case than in the latter. They seem to point to a forcible compression of the atmosphere, and dynamic heating of the cloud-forming strata. And some such temporary effect does not seem impossible, even at a time when the earth’s surface and the air immediately in contact with it are cooling rapidly. Moreover the temperature curves of Prague, Caleutta, and Batavia all show avery slight irregularity about 10 p.m., which indicates a slight check in the fall of temperature about that hour greater than takes place either in the preceding or subsequent hour, and which may possibly be the manifestation of such an action in the lowest atmospheric stratum. Slight as it is, the fact that it occurs at the same hour in all these curves, and that it coincides with the evening pressure maximum and the strongly marked minima of cloud and rainfall, is at least significant. - When we tabulate the differences of the first and second orders of the hourly means of the original observations, at the three stations A424 Mr. H. F. Blanford. The Diurnal Barometric specified, it is found that the second difference corresponding to 10 P.m., with a positive sign, has a greater numerical value than either of those preceding and following it, instead of an intermediate value, as would be the case if the fall of temperature after sundown were decreasing uniformly. In the following tables, the figures for Prague and Batavia represent hundredths of a centigrade degree, those for Calcutta hundredths of a Fahrenheit degree. The figures for Calcutta are derived from only six years’ autographic traces; those for Prague, apparently from eighteen or twenty years’ observations and traces; and those for Batavia from ten years’ readings of a standard thermometer. No correction has been applied to the means of the observations as recorded. Prague (summer). Hows eats que ee eek ke 7 to 8. .t09)4.4040. do 2 ee mad. A, Change of temperature... —115 —94 —8 —s3 —44 A, Change of rate of fall .. +21 +9 +82 +9 Calcutta (year). FLORIS i Nik ape elene 5. to 6: .to.7.,. to:8:.. £09) teeta tea A, Change of tempera- bUTE, ei pee op ty —145 —248 —215 —11l —87 —61 —54 A, Change of rate of fall. popdhs:ae eppeiptag —103 +433 +104 424 +26 47 | Batavia (year). Hours, P.M. ...».--. 5406) to7 to8 to9 to 10 fo tite mud. A, Change of tempera- SITIO? 4 2s gers wieloy> —79 —76 —55 —41 —36 —27 —27 A, Change of rate of pie Ue Meh eeen yy TG +3 +21+14 +5 449 0 The only further point of some significance, to which I have to draw attention, is that the hour of the evening barometric maximum about coincides with the time when the temperature curve ceases to be strongly concave, and becomes nearly rectilinear, indicating a nearly uniform rate of cooling from that time up to just before sunrise. This fact suggests the possibility that the evening maximum of pres- sure may be determined by the check in the descent of the cooling and collapsing atmosphere which takes place from 6 or 7 p.m. to about 10 p.w.* But it is very probably combined with other elements, * This explanation was suggested by Kreil and Espy, and also by myself in a paper read before the Asiatic Society ,of Bengal in 1876. On it Dr. Sprung remarks :—“ Es bleibt aber ginzlich unverstandlich, weshalb dieser Effect, schon um 10 Uhr abends, und nicht zur Zeit des Temperatur-Minimums gegen 6 Uhr ee ee Te ee ee Se Maxima and certain Conditions of Temperature, &e. 425 among which may be the return of the morning wave of pressure. ' And indeed unless there be such repetition, itis difficult to understand why the rise of pressure sets in so early as between 4 and 5 in the afternoon, instead of between 6 and 7 p.m.; that is, after the time when > the fall is most rapid. And unless the evening wave is repeated in | like manner, to explain why the morning rise of adel begins at least two hours before sunrise. Note added August 15, 1888. Since the foregoing paper was read before the Society, I have received a table of the mean horary readings of the thermometer, recorded at the Surveyor-General’s office, Calcutta, (formerly the Calcutta Observatory) during the same years that have furnished the barometric data, quoted in the text, page 415. They have been computed to hundredths of a Fahrenheit degree, and are as follow—(p. 426). The instant of the most rapid rise of forenoon temperature computed from these figures by the method described in the footnote on page 413 is as follows in each month :— _ Max. rise temp. Max. bar. Interval. aeegeaty..... Sh dd3m. 9h. 44m. 0h. 51 m. February.... 8 46 Oo. i Ben: 8 Maeeu SS ce. 8 46 9 47 1 1 is a Be + 22 9° “So | eer i ae 7 «54: oy eae ee PUNE. tienes s- 8 2 a Ei 20 Te ae ie 2 OD 9% 233 | es August OST: eae a | ere | September .. 7 41 9... te ko ae October 7 Ad, ES eS Ad November .. 7 56 9 24 ) ee > December .. 8 56 oom OQ 40 Peat. 8 27 Oe ao I 8 The variations from month to month shown by this table are, as might be expected, less than in the table at page 415 computed from six years only, but the mean interval for the whole year is exactly the same. The irregularity of the evening fall of temperature noticed at page 423 does not appear in the results of this table, and it must therefore remain doubtful whether its occurrence in the three regis- ters quoted in the text is more than a fortuitous coincidence. morgens eintreten soll.” This objection would be quite valid were the cooling of the atmosphere proceeding at an uniform rate, but not, I think, to the actual facts of the case as above set forth. This was not noticed in my former communication, to which Dr. Sprung refers. VOL. XLIY. at 2 a eel Diurnal Barometric Maxima. Mr. F. H. Blanford. | 426 11-99 4 .02.24..| 9P-64 |- 04-18 | 8.18. |.-86-18— |99.c9: || 66-18 ~| “9-08 I eg.94: | e0-.02 F g0.G9 <\***s Fez 06-¢9 | -28:24-| 68-64 | 00-28 | 80-28 | 62-28 } 86:48 | ¢¢.28 {| 92-18 | $9.24 | 98:04 | 68-99. |°"** °"zz OB: 90: © "89-64 | OF- 08. |. 08-28 i) Genee> | “09-28 —| -Speee |. oT-e9 -| “Steg. | 44. 82—- | 96.14 -|- 06-99 «| °° “hg L6- £9 GG. PL 86. 08 99-28 99. Z8 L6-@8 80-F8 |° 12-%8 8Z- &8 SI. 08 ee. 8) 60-891 °° & “tog G6-69 | 09.G4-) ZZ-18 | @1-€8 | $€1-€8: | 0S-e8 | P6-He- |- 42-98 | 21-98 | 90.28 | —20-G4 1° 29-69 “l"°* 6T TI-TZ | ¥0-24 | 8-68 | 88-€8 | 46-€8 | Zb-P8 :| 08-98. | 18-88 | 89-48 | F878 | OG LL |. 9G-TZ [°° o' eT ~9- EL §T- 64 19-78 C6: F8 TO. ¢8 8é-. G8 19-48 |: 18-06 | 09-06:] 8828 GG: 08 ie Ja. 9 | Se Sai 66. £4 09-08 6S. &8 €8- 68 LL. 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KUNE, Professor of Physiology in the University of Heidelberg. Communicated by Professor M. FOsTER, Sec. R.S. Received April 22, Delivered in the Theatre of the Royal Institution May 28, Revised August 15, 1888. (Translation. ) Among the phenomena of life the movement of masses, or mechanical work, takes a prominent place. It is the most accessible of all the vital processes to our sensual perceptions, so universally distributed, and so bound up with most of the activities of organisms, that it might almost be designated the incarnation of life. In saying this it must be understood that vital movement is by no means exclusively confined to animals, that it is not, as was once believed, a special animal function ; on the contrary it is an attribute of all living matter, as well of the lowest creatures as of the most highly developed plants, so that, however extraordinary it may appear, the activity of our muscles which enables us to transform sensation into action finds an analogue in the plant. Our conviction of the inter- connexion and profound unity of all living things has thus a physio- logical foundation, based as it is not merely on the community of derivation and of structure of living things, but also on the proof of similar activities. If a division of the morphological from the physiological is in any way permissible, it may be said that the unitary conception of life for which our age is distinguished rests in a higher degree on the knowledge of vital processes than is commonly recognised, and in fact is just as much founded on physiological experience as on that of the forms of the organism. From the traditional conception of life, which scarcely contained more than that everything between life and death is the antithesis of the not living, it is a long road we have had to travel to attain to the modern conception of the real unity of life; and a remarkable road, since it bears witness to the confident anticipation of victory, in face of all impediments raised up by science itself. Movement, and nothing less, had been placed at the summit of that antithesis, which physico- chemical research in the animal and vegetable kingdom had revived with the discovery that the plant transformed kinetic into potential energy, and the animal the latter into the former. While the animal made use of oxygen to generate heat and perform work through the metabolism of its substance, the plant made use of the heat in reducing 212 498 Dr. W. Kiihne. On the and synthetic processes for the accumulation of potential energy in the form of its own consumable substance and the expired oxygen. With whatever unassailable correctness this conception comprehends life as a whole, affording a pleasing solution of its antithesis by referring animal activities to nourishment by the plant, the latter to the products of the combustion of the animal body, and both in the last instance to the forces of the sun as original source of all life, yet this did but cast up the sum total of the processes of life, and did but express more intimately than before that which divides the most highly developed branches of the animal and vegetable kingdom, in which the divergence of forms and arrangements is greatest. For by the side of this distinction there exists even between man and the most highly elaborated plant a connexion of a kind quite other than the symbiotic interdependence through the medium of light, air, and food, a community, however, which is not disclosed until we go back to the ultimate elements of organisation. As in the animal synthetic processes are not wanting, without which it could not even produce a molecule of the colouring matter of its blood, so in the plant we are acquainted with dissociations and combustion, and also with evolution of heat and movement of masses; not that by this I refer to those coarser movements which are refer- able to turgescence, but primitive movements, which we find first in the smallest elementary organisms, of which all living beings are made up. We have almost in our own persons lived to see the old anticipation of a single kingdom of living things become gradually an established truth through the discovery of the cell. After the ground-lines of the construction of plants and animals out of originally similar nucleated cells had been established by Th. Schwann, and since Darwin’s immortal work enabled us to derive everything that ever lived or will live from one single cell, we have come to realise that every single organism renews in itself the work of past ages, and again builds itself up from a germ similar to that from which its most ancient ancestors started. This conviction has become so firmly implanted in our generation that now we scarcely feel the gaps which still exist in our actual knowledge, and almost unjustly underestimate that which the inves- tigations of our contemporaries yet add to the cell-theory, as if it were mere work of repetition. And yet it has been very extensive and decisive—for example, the recent researches upon the intimate structure of the cell nucleus—since nothing less results from it than that the reproduction of the cell by fission takes place identically, down to the most minute details, in all animals and plants (1).* Now if the shaping of the cell and all the fashioning of forms is an * These numerals refer to the reference notes at end. Causation of Vital Movement. 429 activity, and if Morphology, “since it has made the arising of form more its study than the describing of what is already completed,” has become part of Physiology, it might be possible and conceivable that research directed to all activities and going beyond the visible form to the chemical components of the structures and the transformation of substance and force, should observe great differences in processes where all our morphological experience would only have shown identity. “We were near enough to this point; for if it were true, as was long assumed, that that which is the bearer and the seat of the most essential of all vital processes am the cell is completely form- less, it is not easy to see why the form should be so determinant of function. We have hope that this is not so, and will endeavour to show in Movement the functional as well as the morphological unity of all living matter. As I have already said, there is an elementary kind of movement in the cell, carried out by the cell-body—that part of the cell which in contradistinction to nucleus, membranes, and various enclosures, has been designated protoplasm. The protoplasm moves itself, as in the case of certain free-living Protozoa, like the long-known Ameba, like the so-called Sarcode—in many cases better comparable to the movement of the pseudopodia of Rhizopods. The resemblance of the latter to what was formerly called the sap-current in many plant-cells, led Ferd. Cohn (2) to interpret plant protoplasm as sarcode, an idea actively supported by Max Schultze (3), the best authority on pseudo- podial movement. It is not necessary to say here how widespread protoplasmic movement is, for there cannot be a cell that does not _ present it at some stage of its existence. Doubt on this subject can only exist in regard to the smallest of all organisms, those of fermen- tation, of putrefaction, and of pathogenic activity which are too small for observation. Buteven in these, from the movement they perform as a whole, we have grounds to infer the existence of a protoplasm. It is proved that protoplasmic movement does not follow external impulses or currents, but is a spontaneous activity. It may goon in opposition to gravity, and overcomes frictional resistance, as shown by the mass itself moving forward on surfaces of every kind, and being able to drag heavy bodies along with it. It is proper mecha~ nical work. The cause of the movement can only be an internal one, residing in the contractile substance itself, and can only consist of chemical pro- cesses taking place within the peculiar pasty, slime-like mass. Yet the question had to be put whether these processes were not first set up by something coming perhaps from the outside, for the movement changes, sometimes stops or takes place more slowly, or occurs but par- tially, and may by many means be artificially aroused or diminished. 430 Dr. W. Kiihne. On the At this point experimental physiological research had to step in, attacking the problem in the same way as it had long before done in the case of the most highly developed contractile structures, the muscles. A muscle behaves so far just like protoplasm that its con- traction does work, which can only depend on chemical transforma- tions of its own substance, during which potential is converted into kinetic energy ; but it differs in that a distinct impulse from without is needed to set the game going. In normal conditions it receives the initiating impulse from its nerve, and nothing else appears able to take its place, since nothing that might otherwise act upon it, such as the motion of the blood or changes in its constitution, disturbs its repose. But if we let electric currents traverse the muscle, or if we suddenly change its temperature, or act upon it mechanically or chemically, contractions result which do an amount of work out of all relation to the insignificant impulse; the means employed only set going the process peculiar to the muscle, and this is what is meant when we term them stimuli, and the faculty of muscles to react to them irritability. Now is protoplasm irritable in this sense? Experiments on ob- jects of every kind have answered this affirmatively, and more than that have even shown a striking agreement with the irritability of muscle. Of the above mentioned agents, besides rise of temperature, which ultimately sets all contractile cell-substance in maximal contraction— a heat tetanus (4) which disappears with cooling—the electric current has shown itself the most efficient, the stimulus which most surely excites muscles of every kind as well as all nervous matter, and has thence become the most indispensable instrument of physiology. I may be permitted to adduce an example because it illustrates what is typical and essential (5). It is the case of the fresh water Amcebe. Hvery time these organisms, moving like melting and rolling drops, are subjected to an induction shock they contract almost to a sphere, and assume the spherical form completely if the shocks follow each other at short intervals, being by this means fixed for a longer time in this condition. Feebler shocks which singly have no effect, become effective by summation when applied in quick succession, just as in the case of muscle. If the movements of the animal by itself are sluggish, on electrical stimulation they are strengthened and accelerated. Thus the stimulation increases the natural move- ment, and if increased stimulation brings about repose, it is only the apparent repose of prolonged maximal contraction, like that of our muscles when we hold out a weight for some time at arm’s length. All protoplasm behaves in this way from whatever source derived. Larger masses which cannot contract to one sphere (as in many plant cells, or those great cake-like giant masses of the plas- modium of the Myxomycetes) form several such spheres in part Causation of Vital Movement. 431 connected by thread-like bridges. Hverywhere the taking on of a figure with smallest surface is the result of stimulation, and the expression of augmented contraction (6). That which was outstretched becomes shorter and in like measure thicker, just as a muscle swells when it shortens itself. Since protoplasm, which either does not move at all spontaneously or so slowly that we cannot perceive it, reacts in the same way to stimuli, we must in the case of ordinary movements infer the exist- ence of processes originating them either in the interior, 7.e., automatic stimuli, or of external processes which had at first escaped us. Whoever sees for the first time the action of any one of the simpler independent Protozoa cannot avoid the idea that psychic activity in the strictest sense of the term lies behind it, something like will and design. He sees the elementary being seeking and taking up food, avoiding obstacles, and when touched by foreign objects ener- getically drawing back, so that he infers sensation also. Possibly he has struck the correct solution, at least we could not refute him, but we should put his deduction to a hard proof if we showed him the same phenomena in the colourless cells of bis own blood, or in the protoplasm of a plant-cell; and if we placed before him the rhyth- mically contracting cells from the beating heart of a bird’s egg incubated barely a couple of days, he would certainly wish with us that the search were for a more material cause, and hope that some chemical or physical cause might be found to set up the process. Biology cannot indeed yet claim to have established such causes in explanation of the automatism of protoplasm, but no one will blame the science for continuing the search for them. Some causes are already excluded, e.g., light, although there are a few micro-organisms whose movements are excited by it (7). Fluctu- ations of temperature may also be left out of account. On the other hand, oxygen has a notable influence (8). Withdrawal of the vital air stops all protoplasmic movement, though without killing the cell-body, as is seen from the fact that after the loss of automatism electrical stimulation can supply its place, and that the normal movements return on readmitting the air. : We might thus consider oxygen the prime mover in automatism and processes of oxidation its essence, did we not remember that many objects need very prolonged withdrawal of the gas to come com- pletely to rest. This might, however, depend upon the difficulty of removing the last traces of oxygen completely, or it may be that these cannot be removed by the means adopted, but must remain until consumed by the protoplasm itself. Since protoplasm is of pap-like softness, and may be in a state of rest or motion at any spot, its exterior limits are just as capable of change as everything within it is capable of quitting its position and 432 Dr. W. Kiihne. On the taking up any other. Thus the movement cannot become more ordered until obstacles confine and direct it. Between the perfected organisation of contractile substance in muscle and that of protoplasm capable only of unordered movement, we meet a succession of signi- ficant steps by means of which we can see how the ordering was attained. The first step would seem to consist in the uncommonly widespread flagellar and ciliary motion, in which an elastic structure, affixed on one side to the contractile mass, is drawn down or bent by its movement, straightening out again in the rhythmic pauses of repose. A further step, at which the contraction can only take place along an axis, consists in the arrangement of the protoplasm in fine strips wholly or partially surrounded by elastic walls, or again in elastic fibrils bemg embedded in protoplasmic processes. In this case we have actual primitive muscles before us, of which the most elegant ~ examples are known in the Infusoria among the Vorticelle and Stentores. The movement of these structures is quite like that of muscle. The strips lengthen and thicken, and they may also be con- tracted in quick twitches or in a prolonged tetanus, the relaxing, like the stage of diminishing energy of all muscles, always pro- ceeding more slowly than that of the increasing energy before the maximum. The muscles of the unicellular Infusoria, no longer doubtful in a physiological sense, show us muscle as a constituent of the cell, and differentiation, without the production of new cells specially endowed for the purpose, taking place in one cell to the extent of elaborating contractile elements determinate in form and precise in work. It is very noteworthy that side by side with these muscular strips provided with highly regulated movement, other protoplasm persists, which continues uninterruptedly its ordinary unordered movements, while no such unrest is to be remarked in the muscles. On the contrary, these latter are only used from time to time, apparently for attaining distinct objects. We get the impression that the automatism has, as it were, been lost by this portion, so that it must wait for stimuli to reach it from other parts of the cell. If oxygen really applies the first spur to the protoplasm, it has no direct power over the primitive muscle, so that compared with the protoplasm the muscle is endowed with a diminished irritability. It has often been said that protoplasm presents the complete set of vital phenomena—assimilation, dissimilation, contractility, automa- tism, resorption, respiration, and secretion, and even reproduction by dividing. Leaving reproduction on one side, as now disputed and on good grounds, we can assent to the assertion, and examine which of those functions remain for the products of differentiation. In the case of the muscle, we find it to be all of them with the exception of a single one; for, while it undoubtedly takes part in nutrition as in Causation of Vital Movement. 433 respiration and carries on a chemical exchange, all of which are indispensable for contractility, 7.e., for its work, and since secretion generalised signifies merely the throwing off of broken-down products, it is wanting only in automatism, that faculty of reacting to certain stimuli, which remained reserved for protoplasm. In this there is nothing opposed to the assumption that protoplasm as opposed to muscle possesses elementary nervous properties. The above is sufficient to show the transition to the very highly developed motor apparatus, which distinguishes the animal kingdom from almost its lowest stages—I mean the bi-cellular apparatus, which consists of separate cells united only for one purpose, one of which presents the exciting nerve, the other the obedient muscle. From past experience we know that division of the nerve, or more correctly speaking, removal of the nervous cell substance, condemns the muscle to rest. The stimuli then start from the nerve-cell, to them the muscles react by doing work, and they are conveyed to the muscles through the continuation of the cell which the nerve-fibre presents. Weneed not yet trouble ourselves how the excitation of the nerve-cell arises, whether through external—sensory-—stimuli, or through an enigmatical psychic act, or through chemical influences; certain it is that these were before the division of the nerve the sole impulse to the muscle’s movements. But what the muscles lack we can supply artificially, and more; we can put the nerve-remnant in such manifold states of excitement as it never before experienced from its cell-body, so that the muscle is compelled to undergo many kinds of movement quite new to it, and we can attain the same result by direct stimulation of the muscle. _ In the circle of these experiences arose the controversy, not yet quite ended (9), as to muscular irritability, properly the question whether it was, in general, possible to stimulate anything artificially that is not nerve, that is, to set free the activity peculiar to a non- nervous structure by the means at our command. Haller, who was the first to occupy himself minutely with the stimulation of muscle, and introduced the term irritability, decided, but only incidentally and by the way, that the stimulus could strike also the ramifications of the nerve in the muscle, and he was far from interesting himself in the question in the modern sense, or from suspecting the point of view from which the independent irritability of muscle would later on be questioned. We ought not to blame him much for the latter, since even to-day it is not easy to understand the _ motives of an opposition now continued for more than a century. At the outset, if I am not mistaken, the teaching of the Animistic, or as it might now be called, the Neuristic school, led to the conception that not only the excitation and regulation of the various functions, but the actual endowment of the several tissues with their respective 434 Dr. W. Kiihne. On the activities, was the work of that everywhere predominant and distinctly animal contrivance, the nervous system. In connexion with this, there seems to have arisen the view of the ubiquity of nerves, that is, of so fine a penetration of the parts with nerve radiations that, especially in muscle, not the smallest particle free from nerve could be demonstrated, a view which on the strength of microscopic research is coming up again at the present day in a con- stantly new dress, and finds energetic adherents (10), but as we shall see is to be refuted, especially by experiment. If we disregard this, we shall find the tendency to consider only nerves as excitable, in some degree founded on the differentiation which transferred automatism to the nervous matter, robbing all the remaining tissues of irritability, so that they only retained the faculty of reacting to the stimulated nerve with which they were bound up. This was as much as saying it was impossible artificially to replace the nervous stimulus, or that if we did succeed, we were strictly imitating it, in which case, indeed, we should have come unawares upon the solution of the problem of motor innervation. Against such arguments it availed nothing to point out the excitability of nerveless sarcode, as was often done in favour of irritability : for, just as it was formerly useless, because the real genetic connexion of sarcode and muscle was not known, so to-day it would have to be rejected, because automatic protoplasin can also be correctly considered nervous. | A non-irritable muscle would strike us as strange enough, and, against all expectation, different from the nerve, when we consider that the nerve-fibre, although incapable of being affected by all the natural stimuli which excite its ganglion cells, free that is from auto- matism, is artificially excitable at every spot by the most different agents. However, we have no further need of such considerations, since the question of irritability lies within a region where instead of speculation, observation and experiment have become decisive. As amatter of fact, the older statements, long considered a good basis for opposing irritability, are incorrect, as for instance, that an excised piece of muscle in which no nerves could be seen with the lens did not twitch on stimulating it. We can show you a little piece 3 mm. long from the end of the sartorius muscle of the frog, in which the best microscope discovers no traces of nerves, easily made recognisable by osmium-gold staining (fig. 1). Sucha piece, transversely cut off, twitches as we know at each effective muscular stimulus. Pieces which can be obtained free from nerves from many other muscles, behave in the same way, as for instance pieces from the delicate muscles of the pectoral skin of a frog (fig. 2). Further, the assertion was incorrect that everything that excited the nerve made the muscle twitch, and vice versd; for we see here a See 2 ee" * 64 © aay s <5 at 2 Kips we ‘ Causation of Vital Movement. 435 Fia. 2. sartorius suspended in ammonia vapour, contracting powerfully, while a nerve entirely submerged in liquid ammonia appears wholly unstimulated, for it does not rouse the thigh muscles from their repose. (Hxperiment shown.) Conversely, we see a thigh whose nerve dips into glycerine in maximal contraction, and on the other hand, a muscle in contact at its excitable end with the same glycerine remains at rest, yet it twitches if I dip it in up to its nerve-bearing tracts (11). These are old experiments (12), and it is admitted they have over- thrown the earlier opinion. But they have not been deemed sufficient to prove muscular irritability, because the ultimate endings of the nerves might have an irritability other than that of their stems. This is the only objection still raised. One could wish no other were con- ceivable, for this one admits of refutation. To this end permit me to go a little into detail concerning nerves. Nerves are processes of nerve-cells composed of fibrils of immeasur- able fineness, which in the so-called axis cylinder of the medullated nerves are united by a stroma inside a very fine membrane called the axolemma. In proportion to the microscopic dimensions of the ganglion cells of which the separate nerve-fibres form a part, these latter are for the most part enormously long, many as long as our arms and legs, and that is one of the reasons why the perception of the unicellular nature of the nerves made way but slowly. In fact it was not easy to accustom oneself amid the microscopic swarm of cells, to find single ones so grown in length that they could be wound about us like a cocoon thread. As it is the task and function of the motor nerves to lead towards the periphery the impulses sent out by their ganglion cells in the spinal cord, their activity always admits of ready perception through the muscular twitching. Even when the A36 Dr. W. Kihne. On the nerve is divided and artificially excited at the peripheral end, the muscles betray it. On the other hand, no visible physiological reac- tion is found at the central origin of the motor fibre when stimulated at the periphery, so that at first we were quite in darkness as to whether in general it conducted centripetally. Nature, however, has presented us with a contrivance by which we are enabled to demonstrate the possibility of such an inverted or centripetal nerve- conduction. The contrivance consists in the branching division of nerve-fibres so frequently found in muscles, as will at once be seen in a preparation from a frog (fig. 3). In many muscles these branchings are so arranged that we can use them for an experiment as simple as it is conclusive of nerve-conduction in both directions. Fig. 4. In the gracilis muscle of the frog the nervation is fashioned in the manner displayed schematically upon this diagram (fig. 4.) and in more detail on the following (fig. 5). In reality the arrangement is like this. Now, if I cut up the muscle according to this diagram (fig. 6), we get at the tip Z nerve-fibres which are connected with the muscle-fibres at ‘O and U only by the branchings at the points wx, but which in life served only for the parts of the muscle removed at f and j’. 3 An experiment (18), viz., the stimulation of z (fig. 6), will now convince you that nerves severed from their own muscle-fibres act quite well backwards upon those placed centripetal to them, which they can only do if nerves can also conduct centripetally, and so long as a path is preserved for this through the branchings. If we cut out the neighbourhood of the branchings it isall over with the reaction of the muscle. We can make another experiment on the same muscle (14). We see that when we excite the lower tip of the muscle, only the lower portion twitches and not the upper. The two portions are in fact ie 4 v : Causation of Vital Movement. 437 Fre. 5. Fra. 6. connected only by means of a very short tendon, the so-called inscrip- tion, which passes completely through the muscle (7 in fig. 5), so that it really consists of two muscles. If the nerve common to both is stimulated at any point, then both parts of the muscle contract, but if the muscle substance itself is stimulated, then the contraction travels no further from the place where the stimulus was applied than to the limits of continuity of the muscle-fibres. The power of motor nerves to conduct in both directions is cer- tainly of general significance in regard to the inner mechanism of nerves, but we have only approached it here, because it was necessary for the decisive proof of muscular irritability, as obtained in our last experiment with the m. gracilis. Whenever a muscle is provided with anervation and branchings of the separate nerve-fibres like that of the gracilis, some group of muscle-fibres can serve to indicate whether a stimulus has affected this alone or the nerves lying in it as well. If nerves are present at the point of stimulation, and if the agent was at the same time a nerve stimulus, this is shown by the simultaneous contraction of distant parts which are accessible by means of the nerve’s power of conducting in both directions. In cases where we can see the coarser nervation, the indirectly produced contractions ean be predicted, and these form so certain a criterion of neuro-mus- cular excitations that by them the presence of the finest nerves may be proved, whose existence might otherwise be quite incapable of proof by any other means, as, for instance, by the use of the micro- scope. If these contractions are wanting, as was the case in our experiments with the lower end of the muscle, we know that either the spot stimulated is free from nerves, or that the stimulus employed was ineffectual as to the nerves and affected the muscle substance exclusively. In both cases then independent irritability is proved for those muscle-fibres which were directly excited and contracted. 438 Dr. W. Kiihne. On the Now since we have just employed an electric stimulus which is equally effectual on muscle and nerve, it follows that we had to do with the first case; that is to say, the muscle showed itself free from nerve at its end. We have reason for specially bringing forward this experimental proof of the absence of any kind of nerves in large tracts of muscle, because it compels those who in spite of all assume the presence of nervous matter in certain microscopic disks and strize of the muscle-fibre as a whole, to deny that this supposed nervous element possesses any power of conducting in both directions or any irritability at all; for in fact it is not possible to excite the motor nerve of a muscle-fibre by any stimulus whatever applied to the actual terminations of the nerve within the fibre. The facts besides combine to prove, as need hardly be said, yet another proposition—they prove at the same time that pure muscular excitation does not travel back to the nerves. This may be shown still better with the small pectoral muscles of the frog’s skin than with the m. gracilis. We need only dissect it in Fira. 7. ne | the manner shown in the drawing (fig. 7) and stimulate the spots n and M; if we stimulate m everything contracts, if M the excited half only. The preparation which you now see (corresponding to fig. 2), and which shows the nervation of the very thin muscle with all the nerve- endings stained dark with gold, makes that relation clear, for here again in truth the result of morphological research is in gratifying accordance with results obtained experimentally, The muscle is seen to be for the most part free from nerves; indeed the entire nervation with all the nerve-endings might be said to be formed of one nerve line only, if we disregard the few digressing fibres which again in part are not motor. Under rather higher powers we see the nerve-endings proper (fig. 8), the distinct demonstration of which by means of the gold method has now been achieved, in much the same way as here, in all the classes of vertebrates with the exception of the osseous fishes. In all cases these decisive preparations have proved that the vastly preponderant number of the muscle-fibres is entirely free of nerves, and that the Causation of Vital Movement. 439 Fie. 8. nerve-endings are confined to very small spots which we term fields of innervation. Most muscle-fibres have only one field of innervation, very long ones occasionally several, at the most eight. Thus the assumption, opposed to the idea of independent irritability, that muscle substance is well-nigh completely riddled with nerves, is refuted and rejected from the morphological side also. From the absence of nerves in long tracts of muscle-fibre we im- mediately conclude that the latter shares with nerves the faculty of independently propagating its own excitation. This is what the beau- tiful microscopic observations of Sir William Bowman (15) on insects’ muscles long since led us to suspect. As in the nerve soin the muscle, conduction takes place in every direction, and as the field of innerva- tion almost without exception occupies a median position during a normal contraction, the conduction takes place in both directions, towards the tendinous ends. By way of distinction the velocity of 440 Dr. W. Kiihne. On the © conduction is, according to species, temperature, &c., three to ten times less than von Helmholtz fixed it for nerve. As conduction in irritable tissues means nothing else than that one excited spot becomes the stimulus for the adjoining portion at rest, the in- dependent irritability of the muscle-fibre comes into employment in every movement and during the entire duration of life; from the moment that the field of innervation becomes active all the muscle substance remains left to itself, and until the contraction is ended must be regarded as independent and acting in response to its own direct excitation. Once clear on the fundamental question, and sure as to the method we have to employ in order to stimulate according to choice either muscle or nerve-substance alone, or both together, we may seek to determine in what respect the irritability of the two components of the motor machine differs. The differences as regards chemical stimulation appear very great; in respect of electric, thermic, and _mechanical, on the other hand, only quantitative. However, under chemical stimulation, according to Hering’s classical researches (16), a point formérly overlooked comes into consideration, namely, the com- plication introduced by the electromotive behaviour of the tissue, an automatic electrical stimulation one might say. When stimulation takes place by moistening the transverse section with conducting liquids, it is indeed difficult, if not impossible, to trace the chemical factor in presence of the electrical. Gaseous stimuli alone, like am- monia, have thus far remained free from the suspicion of acting electrically. To these a few others of similar action, such as bisul- phide of carbon (17), have been added, and such as are conveyed to the muscle by the blood-vessels, and bathe the fibres from all sides. With these in particular we may class distilled water, which is excessively destructive to irritable substances, von Wittich (18) being the first who showed how strongly it stimulates muscles, while killing nerves without excitation. But, again, with this kind of stimuli, we cannot at present tell whether they do not set up in the tissues, over narrow but numerous areas, excitatory electric currents, thus working only indirectly by way of auto-electric stimulation. And since, finally, the same might apply to the thermic and mechanical actions which lke- wise arouse demarcation currents in the muscle, that is, to all stimuli, we find ourselves in the presence of the possibility of reducing all irritability to a reaction to electrical processes, and of seeing vital electricity elevated into immeasurable importance. The means by which muscle may be stimulated interests us, in the first place, on this account—to ascertain, once for all, how it procures its excitation in life, or what may be the action of nerve upon it. Did we know that, we should have grasped at the same time the nature of nervous activity. Causation of Vital Movement. 44] Nerves end blindly in the muscles; as a rule they are not even finely pointed, and still less do they spread out diffusely in such a way as might make the true ending difficult to find. They end quite dis- tinctly. But the ends always lie beneath the sarcolemma, in such a way that no foreign tissue intrudes between them and the muscle, so that what is fluid in the muscle can directly moisten the nerve. The sub- lemmal nerve is clothed with nothing else than the axolemma. The nerve never Jenetrates into the depths of the muscle substance ; on the contrary, it remains confined to the sublemmal surface of the contractile cylinder or prism. Hach nerve end consists of several branches, like antlers, arising by division, which together form the terminal nerve-branch. Apart from the form of the antlers, this short description is exhaustive for many animals, since neither in the sub- lemmal nerve need any special additional structures occur, such as nuclei, nor any kind of modification of the muscle substance in the field of innervation. There is much to indicate that the nerve-fibre proper, or axis-cylinder, does not change its constitution in passing through the sarcolemma, still it is to be remarked that the twigs of the terminal branches, although as long as they live often apparently longitudinally striated, have not yet, even in the most favourable stainings, been found to present the general fibrillar structure of nerves. According to these results of morphological research, it appears that contact of the muscle substance with the non-medullated nerve suffices to allow the transfer of the excitation from the latter to the former. The only strange thing is that in reversed order ‘excitation of the muscle never extends to. its own nerve. This is still stranger because, according to Matteucci’s well-known discovery, a foreign medullated nerve simply laid upon the muscle is powerfully excited by the contraction—so powerfully that the smallest contracting muscle barely touching it in more than a mere point excites the strongest nerve, while, on the other hand, we never see muscles excited by nerves which are merely pressed against them. In the investments, then, of the nerve and the muscle substance appears to exist one of the elements which admits the neuro-muscular excitation exclusively to the field of innervation, and among those investments it need not be the medullary sheath. The delieats membranes of the sarcolemma and neurilemma suffice, for muscle cannot be excited by superimposed non-medullated nerves. At any rate, I have tried in vain to excite muscles by the most intimate _ contact of the fine terminal ramification of the optic nerve in the retina or the n. olfactorius from the pike, or even the delicate nerves of Anodonta, by stimulating these non-medullated nerves. If we imagine the activity of the nerve to start with a chemical process, and that a chemical stimulant, as du Bois-Reymond (19) once VOL. XLIV. 2K A42 | De WV. ‘Keke, wae suggested, is, at the same time, secreted in contact with the muscle, we understand very well the necessity of direct contact, and in this case it would suffice if the sublemmal nerve were to run in any form for a short distance under the sarcolemma. The branching then would mean the enlarging of the contact. But however rich and intricate the ramifications may be, we can by no means say they display throughout the principle of increase of superficies; on the contrary, they are often astonishingly poor and small. As concerns their form, they are not irregular, but so strikingly uniform that this point deserves particular attention as being apparently indispensable for innervation. Instead of describing the forms, allow me to show you the object itself in a selection taken from the most diverse vertebrates. First from the Amphibia (fig. 9): rod-like branchings with long outstretched twigs, a form which crops up again in a remarkable way in many birds. The rule here is asymmetry of the divisions: all the twigs have the form of a bayonet. Fra. 9. The following preparation shows the termination in the dog (fig. 10). Here the branches are crooked, and hence quite divergent, so that the points of agreement with the form of the Amphibia are at first over- looked. But if we examine the divisions, you will remark that these are again unsymmetrical and give off branches whose ends lie very diversely removed from the common place of origin. The ends are, as a rule, turned towards each other, and often so approximated that it is at times troublesome to find the gaps between them, and if they do not lie in the same plane they appear to be united into a ring. In other cases one end overlaps the other, but we then find that all the points of the branches which are turned towards each other lie at unequal distances from the nearest bifurcation. This law holds good in all the thousand cases of motor endings thus far observed and shows a strict order in the apparent chaos of these structures. And yet among the organic forms there is scarcely one which varies so much in other respects and often is so inextricably complicated as this. The drawings (fig. 11, from the muscles of the guinea-pig, and fig. 12 of the rat) and a preparation from a lizard (fig. 13) may serve Causation of Vital Movement. 445 Fre. 11. rg. le as a voucher for the truth of the above statement. We see there everywhere the hooks making their appearance with a short and a long claw, like the swivel we hang our watch on in the pocket. The voluntary muscles of all vertebrates and of many invertebrates consist of fibres, the contents of which are perfectly regularly dis- posed in layers and transversely striped. For shortness, this striped mass may be called ‘“‘rhabdia.”” This it is which has been universally identified with the contractile substance. But it has been ascertained that in many cases the nerve-ending does not come at all into direct contact with the rhabdia, but with another mass, which is highly nucleated and of pap-like softness. This latter is unstriped, and has all the appearance of protoplasm. It occurs in very varying quantity under the nerve-antler; in Amphibia, where the sublemmal nerves run out in a long course, it is not apparent as a separate layer, but it occurs more abundantly in the same measure as the branchings retract, and the field of innervation becomes smaller. . At first it is found chiefly between the twigs, in the intervals of the branching, and then in the form of a “ sole,” which among the much contorted branchings of reptiles and mammals grows thicker, till it sometimes in some nerve eminences forms quite a thick cushion. Since we have succeeded in making the nerve-endings visible in uninterrupted series of very fine sections of mammalian muscle stained with gold, there can no longer be any doubt that the complete separation of the sublemmal nerves from the rhabdia by measurable layers of sole-protoplasm, though not the rule, is yet by no means rare, and that many muscles possess no other sort of nerve-endings than such as these with apparently indirect contact (20). It would be ditficult to understand why the innervation should have in some muscles, as in the Amphibia, no intermediate layer while haying in the majority of cases an interrupted layer, and in others a continuous layer of varying thickness to traverse. But when we consider what the substance of the sole is, of what it consists, how it is distributed, and when we know its origin, it appears that it is oo A444 Dr. W. Kiihne. On the identical and stands in continuous connexion with the long-known second constituent of muscle-fibres, of which as well as of the rhabdia the fibres are composed. It is that substance, considered by Max Schultze to be the protoplasmic remnant of the cells composing muscle, which occurs in greatest amount around the nuclei of muscle, and extends in long threads throughout the entire muscle-fibre. So many transverse connexions occur on the very numerous stronger and finer nucleated threads that the whole mass, called sarcoglia, becomes a trellis-work almost of the same fineness as the better known trans- verse striation of the rhabdia, and everywhere surrounds and inter- penetrates the latter. This minute internal structure of muscle has only become at all well known since the introduction of gold staining, thanks especially to Messrs. Retzius and Rollett (21). Had it been sus- pected earlier, and had we appreciated the volume of the sarcoglia whose existence is thereby shown and which rivals that of the rhabdia, we might have studied this component of muscle in its physiological relations to contractility, as well as in its morphological and genetic relations which are the only ones yet known. If now in many cases it appears that the nerve comes in contact only with the surface of a thick layer of sarcoglia, while the rhabdia everywhere is covered by very fine layers of the latter, whose absolute absence in the field of innervation can nowhere be demonstrated, we have to conclude that in general the nerve does not act directly upon the rhabdia, but only on the sarcoglia. This at once gives the latter a physiological interest. We have to ask whether the glia is the medium that conducts the stimulus between nerve and rhabdia, or whether it is itself the contractile element while the rhahdia has a signification other than that formerly attributed to it when we were completely ignorant of the gha. All contractile substance requires the co-operation of an elastic element. Where is this to be found in the musele-fibre? The envelope of sarcolemma which is certainly elastic but delicate, and whose mass is almost infinitesimal compared with that of the muscle- fibre, cannot satisfy the requirement; but more solid structures freely distributed in the paste-like sarcoglia could perhaps do so, and such we find in the rhabdia, in the form of prismatic particles ranged with such constancy and with such regularity longitudinally and trans- versely, that we may hold them to be the elastic element. Then the sarcogla would become the contractile element, and the nerve would have an easier task. I could wish that this view might be accepted as an hypothesis. As far as I can see it does not contradict experience, for it only puts back the muscle nearer to the protoplasm and to all that is con- iractile, and so far coincides with experience that we find muscles in the same measure less elastic and more sluggish in protoplasmic Causation of Vital Movement. 445 movement the richer they are in sarcoglia, as in the case of the red muscles, nucleated and rich in glia, which contract more slowly but with greater power than the white muscles poorer in glia which are quick and spring-like, and also the sluggish embryo muscles, in which glia predominates because as yet but little protoplasm has been converted into rhabdia; and further the cells of unstriped muscle-fibre, which are wanting in the regular transverse striation, and contain, as it appears, besides more abundant glia, an elastic material of special form and arrangement. The hypothesis would be overthrown if contractile fibrils were found in which no sarcoglia was to be detected. But evenin the finest fibrils of Stentor, the structure of which Biitschli (22) has recently elucidated, we must hold the significance of punctated transversely penetrating indentations to be protoplasmic, and we can therefore scarcely expect ever to find a contractile thread in which nothing whatever should be found of the primitive contractile material such as 1t everywhere exists. Of late this view (23) has been defended from the purely morpho- logical side (24), on the strength, namely, of the very fine reticular structure of protoplasm to which more attention is being paid, and which is demonstrable on objects of all grades of organisation. Proto- plasm, in fact, is not so formless as at first appeared, but shows a structure comparable with nothing better than with the appearance presented by a transverse section of muscle with its gla framework stained with gold. We may expect that these reticular structures, whose consistency appears to vary extraordinarily, will some day lead to the establishment of a fruitful hypothesis of the inner mechanism of protoplasmic movement, in place of that held hitherto which affords no glimpse into the essence of vital mechanical work. Compared with this larger problem, that of the causation of vital movement appears the more accessible of the two, the latter being con- sidered as a physiological inquiry after the constitution of the normal stimulus by which work is done. Perhaps, indeed, the answer is to be looked for from the most perfected organisation of muscle, where the initiatory process is localised by a distinct nerve-ending, rather than from the primitive organisation where the excitation may set in at any place, and lies in the protoplasm itself. We know dis- tinctly that the muscle-wave begins in the field of innervation, for we have long seen the natural contraction in the interior of trans- parent insect larve starting from the nerve eminences. We know this also from the experiments of Aeby, who followed the muscle-wave myographically from the nerve-line onward, and now we are able to display the beginnings of the contraction as local thickenings at the point of attachment of the nerves caught and fixed by sudden harden- ing. Since the nerve grasps the muscle in a restricted region it 446 Dr. W. Kiihne. On the expends its action upon this exclusively; that which follows on as muscular activity is the nerve’s work no longer. Galvani and his successors for more than a century suspected that nervous forces were electrical, and, in reality, the celebrated champion of electro-physiology in our day has been able with the galvanometer to render the excitation of nerves, unattached to muscles or ganglion- cells, evident as the negative variation of the natural nerve-current, to cause movement of a magnetic needle instead of a muscle, or to put the needle in the place of sensation. After this no consideration of the nature of nervous activity is conceivable which does not take into consideration this discovery of du Bois-Reymond’s—least of all where the nerve has to excite something with which it is not fused, like muscle, but which it only touches, and that not directly, while still invested by the axolemma. Only during excitation, as Ludimar Hermann has taught us, are electric currents issuing from the nerve through its conducting surroundings, in which the course of these currents of action is to be estimated from the duration of the negativity of the nerve-tract excited, and from the speed of propaga- tion of the nerve-wave, if we know the conductor and the disposition of the nerve. The motor ending fixes the latter, and so peculiarly that we can only presuppose from it a furthering of the excitor effects of the currents of action. The currents of action of muscle, whose electromotive behaviour agrees so wonderfully with that of nerve, have long been proved to produce excitor effects, although only powerful enough to act upon nerves; but there are also, under certain conditions discovered by Hering, such effects from nerve to nerve (25). Is the possibility, we may hence ask, to be excluded of one muscle exciting another, and is it quite impossible that a nerve only throws a muscle into contraction by means of its currents of action r The first question we can answer. I will do so by a simple experi- ment. T'wo muscles, the nerves of which are disposed of by poisoning with curare, need only to be pressed together transversely over a narrow area to make a single muscle of them of double length, in which the stimulation and contraction are propagated from one end to the other. Since the transference from one muscle to the other is done away with as soon as we bring the finest gutta-percha between the muscles as an insulator, or gold-leaf as a secondary circuit, the first muscle must have excited the second electrically (26). NOTES. 1, The most complete exposition of these important later discoveries on the reproduction of the cell is to be found in the book of W. Flemming, ‘ Zellsub- stanz, Kern und Zelltheilung,’ Leipzig, 1882. Cf. the ‘“‘ Kurze historische Ubersicht ” (p. 385), with the quotations from the works of Schneider, Strassburger, Biitschli, Causation of Vital Movement. 447 Flemming, O. Hertwig, and the researches of Auerbach, Balbiani, van Beneden, Eberth, Schleicher, Balfour, and others. 2. Ferd. Cohn: “ Nachtrage zur Naturgeschichte des Protococcus pluviatilis.” ‘Nova Acta Acad. Leopold. Cexsar.,’ vol. 22, P. II, p. 605 (1850). 3. Max Schultze. ‘Ueber den Organismus der Polythalamien.’ Leipzig, 1854. 4, W. Kiihne: ‘ Untersuchungen tiber das Protoplasma und die Contraktilitit.’ Leipzig, 1864, pp. 42, 66, 87, 102. 5. Kiihne: 7bzd., p. 30. 6. Th. W. Engelmann five years later confirmed the passage of protoplasm, especially of Amceba, to the spherical form on stimulating; cf. his “ Beitrige zur Physiologie des Protoplasmas,” ‘ Pfliiger, Archiv,’ vol. 2, 1869, p. 315, and ‘ Hand- buch der Physiologie, herausg. von L. Hermann,’ vol. 1, p. 367. 7. Engelmann : “ Ueber die Reizung des contraktilen Protoplasma durch plitz- liche Beleuchtung.” ‘ Pfliiger, Archiv,’ vol. 19, p. 1. 8. Kiihne, /.c., pp. 50, 67, 88-89, 104-106. The cessation of the so-called sap-' stream in the cells of Chara on excluding the air by oil was observed as far back as 1774 by Bonaventura Corti; and further by Hofmeister in Witella under the influence of reduced atmospheric pressure. Cf. Engelmann in ‘Handbuch der Physiol., von Hermann,’ vol. 1, Part 1, p. 362. 9. Cf. J. Rosenthal: ‘ Allgemeine Physiologie der Muskeln und Nerven.’ Leipzig, 1877; p. 255. 10. J. Gerlach: ‘“ Ueber das Verhalten der Nerven in den quergestreiften Muskelfaden der Wirbelthiere.” ‘Hrlangen, Phys. Med. Soe. Sitzber.,’ 1873.— ‘Das Verhaltniss der Nerven zu den willktirlichen Muskeln der Wirbelthiere.’ Leipzig, 1874.—“ Ueber das Verhiltniss der nervésen und contraktilen Substanz des quergestreiften Muskels.”” ‘Archiv Mikrosk. Anat.,’ vol. 13, p. 399. A. Foettinger: “Sur les terminaisons des nerfs dans les muscles des insectes.”’ ‘ Archives de Biol.,’ vol. 1, 1880. : Engelmann : ‘ Pfliiger, Archiv,’ vol. 7, 1873, p. 47; vol. 11, 1875, p. 463; vol. 26, p. 531. _ In these publications it is sought to prove that the motor nerves pass either into - the interstitial nucleated substance of the muscle (therefore into the sarcoglia) or into the layers of the “Nebenscheiben.” This latter view is opposed by, among others, A. Rollett in his thoroughgoing exposition of the structure of muscle (Vienna, ‘Denkschriften der k. Akad.,’ vol. 49, p. 29), and W. Kiihne (‘Zeitschr. f. Biol.,’ vol. 23, p. 1). 11. The experiments were performed during the lecture by projecting on the wall images of the preparations enlarged some thirty times. 12. Kiihne: ‘Ueber direkte und indirekte Muskelreizung mittelst chemischer Agentien.” ‘ Miiller’s Archiv f. Anat.,’ 1859, p. 213. 13. Kithne: “Ueber das doppelsinnige Leitungsvermégen der Nerven.” *Zeitschr, f. Biol.,’ vol. 22, p. 305. To demonstrate the experiment on the gracilis, the muscle was fixed ona white piece of cork by needles, and held by elastic holders, and its image thrown on the wall highly magnified by a Kriiss lantern. 14. Kihne: 7bid., pp. 312, 324. 15. William Bowman: “On the Minute Structure and Movements of Voluntary Muscle.” ‘Phil. Trans., 1840, p. 457; and “ Muscle—Muscular Motion” in the ‘Cyclopedia of Anatomy and Physiology,’ edited by B. B. Todd, vol. 3, 1847, pp. 506-530. 16. EH. Hering: “Ueber direkte Muskelreizung durch den Muskelstrom.” Vienna, ‘Sitzber. k. Akad.,’ vol. 79, Abth. 3, 1879. 17. “Ueber chemische Reizungen; nach Versuchen von stud. med. ©. Tani.” ‘ Untersuch. aus der Physiol. Instit. der Univ. Heidelberg,’ vol. 4, 1882, p. 266. 448 — Dr. E. Schunck. 18. v. Wittich: ‘ Experimenta quaedam ad Halleri doctrinam de musculorum irritabilitate probandam instituta. Kénigsberg, 1857, and ‘ Virchow, Archiv,’ vol. 18, 1858, p. 421. In these papers, with the discovery of the excitation of muscle by distilled water, appears without doubt the first fact which overthrew the old theory of the equal irritability of muscle and nerve. 19. H. du Bois-Reymond : ‘Gesammelte Abhandlungen zur allgemeinen Muskel- und Nervenphysiologie ;’ vol. 2, p. 700. 20. Kiihne: ‘ Verhandlungen des Naturhist.-medicinischen Vereins zu Heidel- berg ;’? Neue Folge, vol. 4, pp. 4, 5. 21. G. Retzius: ‘Biologische Untersuchungen,’ 1881. A. Rollett : “ Untersuchungen tiber den Bau der quergestreiften Muskelfaser.” ‘Wien, Akad. Denkschr.,’ vol. 49, 1885. 22. ‘Dr. H. G. Bronn’s Classen und Ordnungen des Thierreiches, neu bearbeitet von O. Biitschli.’” Leipzig und Heidelberg, 1888, vol. 1, p. 1298. 23. Kihne: “Neue Untersuchungen tiber motorische Nervenendigung.” ‘ Zeitschr. Biol.,’ vol. 23, pp. 88-95. 24, A. van Gehuchten: ‘“ Etude sur la structure intime de la cellule musculaire striée.”’ ‘La Cellule,’ vol. 2, p. 289. 25. H. Hering: ‘Sitzber. der k. Akad. zu Wien,’ vol. 85, Abth. 3, 1882, p. 237. 26. Kiihne: “ Secundire Erregung vom Muskel zum Muskel.” ‘ Zeitschr. Biol.,’ vol. 24, p. 383. The drawings, figs. 1, 2, 3, 5, 8 are taken from the papers of Dr. K. Mays: “ Histophysiologische Untersuchungen tiber die Verbreitung der Nerven in den Muskeln”’ (‘Zeitschr. Biol.,’ vol. 20, p. 449), and ‘‘ Ueber Nervenfasertheilungen in den Nervenstiimmen der Froschmuskeln” (‘Zeitschr. Biol.,’ vol. 22, p. 354) ; figs. 9—13, from the author’s work in ‘ Zeitschr. Biol.,’ vol. 23, pp. 1—148, Plates A—Q. “ Contributions to the Chemistry of Chlorophyll. No. II.” By EDWARD SCHUNCK, F.R.S. Received June 19,—Read June 21, 1888. Products of the Action of Alkalis on Phyllocyanin.—In the first part of this memoir I gave a general account of the action of alkalis on phyllocyanin (‘ Proceedings,’ vol. 39, p. 355). I shall now proceed to give the results obtained on further examining the products due to this action. The description of the products appearing in the first stage of the process of change induced by alkalis forms the subject of the present communication. The great trouble involved in preparing any connie quantity of phyllocyanin in a state of purity made it desirable to find out a method, if possible, of obtaining the products of the action of alkali directly from chlorophyll itself. The object in view was attained by acting on chlorophyll first with alkali and then with acid, thus reversing the process previously adopted and at the same time leading to the discovery of several new and interesting compounds, the formation of which had not been anticipated, Contributions to the Chemistry of Chlorophyll. 449 The plan I have pursued is as follows :—Fresh leaves—I prefer grass with broad blades to any other material—are exhausted with boiling spirits of wine containing from 80—82 per cent. of alcohol. The green extract is filtered hot, and being allowed to stand for a day or two away from the light, yields a dark-green voluminous deposit, containing chlorophyll mixed with fatty and other matters. This deposit is filtered off for further treatment, the pale-green filtrate being rejected. The green mass on the filter is now to be treated with a boiling solution of caustic soda in strong alcohol, which dissolves it in part. The insoluble portion is filtered off, and after washing with alcohol appears almost white.* Through the dark- green filtrate a current of hydrochloric acid gas is then passed until it acquires a strong acid reaction. The liquid first becomes yellowish- green, but after some time the colour changes to a dull purplish- green, and small crystalline needles arranged in stars, purple by reflected and dull-green by transmitted light, begin to appear on the * Minute sparkling red crystals are always found interspersed in the amorphous mass of which the residue left by alcohol for the most part consists. These crystals are the chrysophyll of Hartsen, the erythrophyll of Bougarel, a very beautiful substance, which may be freed from the impurities accompanying it in this case in the following manner :—The residue, after washing with alcohol, is treated in the cold with chloroform, which dissolves the chrysophyll, leaving the greater part of the fatty matter behind. The yellow solution is filtered, mixed with a considerable quantity of alcohol, and left to stand for a day or two in the dark, when it deposits erystals of chrysophyll mixed with fatty matter. The deposit is filtered off, and placed, without removal from the filter, in a hot water funnel; here it is treated with a little hot glacial acetic acid. This removes all the fatty, along with some colouring, matter. The residue is dissolved in a little chloroform, and the solution, having been mixed with several times its volume of absolute alcohol, is left to stand in the dark. The next day a quantity of chrysophyll will have separated in crystals with a golden lustre and of a deep orange or red colour by transmitted light. The substance is rapidly bleached on exposure to air. In order to preserve it unchanged, it should, after filtration and rapid drying, be put into a glass tube through which a current of hydrogen is passed before sealing, then kept in the dark. According to Arnaud (‘Compt. Rend.’ vol. 102, p. 1119, and vol. 104, p. 1293), chrysophyll is identical with carotin. There can be no doubt that it contributes to the obscura- tion at the blue end of the ordinary chlorophyll spectrum; I have found it accom- panying chlorophyll in all leaves that I have examined. Its solutions when sufficiently dilute show two broad bands at the blue end, without the least trace of absorption at any other part of the spectrum (fig. 1). Fie. 1. Absorption Spectrum of Chrysophyll. bo me VOL. XLIV. 450 Dr. E. Schunck. sides of the glass. These needles continue to increase in quantity for some time; they are filtered off, washed with alcohol, and then treated with boiling ether, which removes a quantity of fatty matter, at the same time dissolving some of the substance itself. The residue is dissolved in a small quantity of chloroform, and the solution which is deeply coloured is then mixed with several times its volume of absolute alcohol. On standing, the liquid deposits a quantity of long crystalline needles, which are collected on a filter and washed with alcohol, in which they are only slightly soluble. The substance thus obtained is apparently an ethyl compound, and is probably the ethyl ether of the product formed by the action of alkalis on phyllocyanin, this being the conclusion to which its reactions seem to point. In mass it appears of a fine purplish-blue, and shows a semi-metallic lustre. Under the microscope it is seen to consist of acicular crystals, which are mostly opaque, but when very thin are transparent, and appear pale olive-coloured by transmitted light. It softens at 205° C., but it has no-definite melting-point. When strongly heated in a glass tube it is decomposed without yielding any crystalline sublimate, leaving a voluminous charcoal; heated on platinum it burns away without leaving any ash. It is insoluble in water, sparingly soluble in boiling alcohol and ether, more easily soluble in benzol and carbon disulphide, and very easily soluble in chloroform. The solutions when diluted have a dull-purplish or pink colour, and show an absorption spectrum identical with one already depicted as belonging to one of the derivatives of phyllocyanin (‘ Proceedings,’ vol. 42, Plate 1, fig. 13). It dissolves in boiling glacial acetic acid and crystallises out on cooling. It is also soluble in concentrated hydrochloric acid, giving a solution which has the same greenish-blue colour, and shows the same absorp- tion-bands as a solution of phyllocyanin in the same menstruum, but on the addition of water it is precipitated unchanged. The quantity of the product, in a crude state, obtained by the method described, amounted to 4°5 parts from 1000 of dry grass. When methylic alcohol is employed in the extraction of fei and the same process as that above described is gone through, a similar compound is obtained, but differing from it in some respects. It crystallises in lustrous purple needles, rather lighter in colour than those from ethylic alcohol; it has no definite melting point; it is hardly soluble in boiling alcohol or ether, but easily soluble in chloro- form, the solution showing the same absorption-bands as that of the other compound. It can hardly be doubted that this is the corre- sponding methyl ether. These compounds are insoluble in aqueous alkalis, and are very little changed by prolonged boiling therewith, but on treatment with alcoholic potash or-soda they are immediately dissolved and decom- posed. The process is apparently one of- saponification, the product Contributions to the Chemistry of Chlorophyll. 451 being the substance of which the compounds are the ethyl and methyl ethers respectively. In order to obtain this product the ethyl com- pound is treated with boiling alcoholic soda, in which it readily dissolves. The solution on standing deposits a sodium compound in the shape of a dark-green, almost black, semi-crystalline mass, which is filtered off, washed with absolute alcohol, and dissolved in water. The dark-green solution gives with acetic acid, of which a great excess must be avoided, a green flocculent precipitate, which is filtered off, thoroughly washed with water, and dissolved in ether. On slow evaporation the ethereal solution yields lustrous purple crystals, which must be separated before the solution has quite evaporated, for if there be any free acid present this will after most of the ether has evaporated, begin to act on the substance, inducing a change to which I shall allude presently. The substance thus prepared is identical with that formed directly by the action of alkali on phyllocyanin, brt by the process just described it is obtained in a state of much greater purity than by the direct method. Having read nearly everything that has been written on the chemistry of chlorophyll, I have come to the conclusion that this substance has never previously been described, and I think myself entitled therefore to give it a name. I propose to call it Phyllotaonin (from tauv, a peacock). Properties of Phyllotaonin.—On spontaneous evaporation of its ethereal solution, it is obtained in regular flattened crystals or crystalline scales, which by reflected light appear of a fine peacock or steel-blue colour; the crystals are mostly opaque, but when very thin they are transparent and then appear brown by transmitted light. It melts at 184° to a brown resinous mass, but partial decomposition results from fusion, since the melted mass is no longer entirely soluble in chloroform, a little carbonaceous matter being left undissolved. Heated on platinum it swells up, giving off much gas and leaving a voluminous coal which burns away without residue ; heated in a tube it swells and is charred without giving any perceptible sublimate., Phyllotaonin is insoluble in boiling water. It is easily soluble in boiling alcohol and ether, but it does not crystallise out on the solutions cooling; the solutions have the same colour, and show exactly the same absorption-bands as solutions of phyllocyanin, but if the least trace of any acid be present in the solution the spectrum gradually changes, the third band from the red end becoming fainter, while the fourth band as well as the first splits up into two. It is soluble in benzol and carbon disulphide, and very easily soluble in chloroform and aniline, but insoluble in ligroin. Phyllotaonin is easily soluble in glacial acetic acid, giving a solution of a fine violet colour, which shows a spectrum differing from that of the ethereal solution, and by this means it may be at once distinguished from 2u2 _ AE? Dr. E. Schunck. phyllocyanin, which dissolves in ether and in acetie acid, both solutions having a dull green colour, and showing the same spectrum. It is also soluble in concentrated hydrochloric acid, the solution having a bright bluish-green colcar. In contact with acids phyllotaonin undergoes a series of changes, accompanied by corresponding changes in the absorption spectrum. If to an ethereal or alcoholic solution of phyllotaonin a small quantity of an acid, such as hydrochloric, sulphuric, oxalic, tartaric or acetic acid be added, the colour of the solution changes slowly from green to brown, and now shows the spectrum frequently referred to in which two bands, that in the red and that in the green, are seen split up into two (see fig. 11 of the Plate previously referred to). A further change takes place on standing, one of the bands in the green becoming darker, the other lighter (see spectrum, fig. 12). Here the action stops with all the acids named except acetic acid. On treating phyllotaonin with boiling glacial acetic acid it dissolves, and the dark purple solution if sufficiently concentrated deposits on cooling crystalline needles, arranged in fan-shaped masses. These collected on a filter and dried show a fine purple colour, and closely resemble the supposed ethyl-compound of phyllotaonin ; its solutions show the same absorption spectrum as the latter. This product is doubtless a compound with acetic acid; stronger acids such as sulphuric or hydrochloric acid yield no similar compounds. ‘The products formed by the action of acids may in all cases be re-converted into phyllotaonin by means of alkali. The process of re-conversion may be traced in its course with the crystallised acetate. If the latter be treated with aqueous potash in the cold it dissolves; acetic acid added gives a green precipitate which dissolves in ether, the solution showing the spectrum of fig. 11, but if boiling alcoholic potash be employed, the corresponding ethereal solution shows the spectrum of phyllotaonin. Under the influence of acetic acid the latter again passes through the series of changes previously described. That the changes induced on the one hand by acids, and on the other by alkalis, are due in one case to hydration and in the other to dehydra- tion, seems probable. After being heated to the melting point, phyllotaonin gives solutions showing the spectrum, fig. 12, but by treatment of the fused substance with alcoholic potash it returns to its original state. It is difficult to attribute the change in this case to anything but loss of water, the latter being taken up again on treatment with alkali. A potassium compound of phyllotaonin is obtained on adding potash to an alcoholic solution of the substance; it crystallises in needles which are purple by reflected light. The sodium compound obtained in the same way is hardly crystalline. A boiling alcoholic solution of phyllotaonin to which cupric acetate and acetic acid have Contributions to the Chemistry of Chlorophyll. 453 been added, deposits on cooling and standing a quantity of crystalline ‘needles arranged in pretty rosettes which, after filtering off and dry- ing, appear bluish-green by reflected as well as by transmitted light, and show no metallic lustre; the alcoholic solution of this compound shows the same absorption spectrum as that of. the corresponding phyllocyanin compound, and, like the latter, it is not decomposed nor in any way changed by treatment with boiling hydrochloric acid. Similar compounds containing iron and silver may be obtained, but their properties are not sufficiently interesting to merit detailed descrip- tion ; they resemble the corresponding phyllocyanin compounds. On adding metallic tin to a solution of phyllotaonin in hydro- ehloric acid and allowing to stand, the solution soon loses its bright bluish-green colour, and becomes olive-green, finally reddish-yellow. Water now gives a red precipitate, which filtered off and washed dissolves in alcohol with a crimson colour, the solution showing a spectrum similar to that of the final product of the action of tin and hydrochloric acid on phyllocyanin. Though there can be little doubt as to the purple crystals formed by the action of hydrochloric acid on an alcoholic solution of alkaline - chlorophyll being an ether, I have not succeeded in reproducing it by the direct action of acid on an alcoholic solution of phyllotaonin. The solution retains its bluish-green colour unchanged, deposits no crystals even on long standing, and gives with water a precipitate consisting of uncombined phyllotaonin. A compound resembling that in the purple crystals may, however, be formed from phyllotaonin by a different process. If to an alcoholic solution of phyllotaonin ethyl iodide and a little caustic potash be added, the solution on boiling deposits a small quantity of a black powder, which being collected on a filter and treated with dilute acid, is found to be soluble in alcohol, ether, and chloroform, giving purple solutions which show the same spectrum as solutions of the purple crystals. It is, however, easily soluble in aqueous alkali, and may therefore be a mono-ethyl, the other being a di-ethyl ether. It is probably identical with the com- pound formed directly from phyllocyanin by a similar process, as described in the first part of this memoir, in the solutions of which the spectrum (fig. 13) so frequently referred to was first observed. This very peculiar spectrum belongs, it appears, to four distinct compounds. In order to explain the formation of the purple crystals by the process above described, we may suppose that by the influence of alkalis chlorophyll is first converted into a substance which by decom- position with acids yields phyllotaonin, and this in the nascent state and in contact with alcohol and hydrochloric acid undergoes etheri- fication. Of the compounds above described I have analysed such as were 454 Contributions to the Chemistry of Chlorophyll. well crystallised and appeared to be pure, but I will not give the results until I have had an opportunity of confirming them with ° freshly prepared material. The difficulty experienced in preparing sufficient quantities of pure substances from chlorophyll has proved a great drawback in this investigation and has much retarded its progress. My friend Dr. Burghardt, of the Owens College, has had the kindness to examine at my request the crystalline form (fig. 2) of phyllotaonin, and reports as follows :— BiG. 2. Crystal system monosymmetrical, oblique rectangular prism, formed by the combination of the ortho- and clino-pinacoids. The terminal faces are a negative hemipyramid. The faces b (010 Miller or aa Naumann) predominate, giving a “ vertical tabular habit ”’ to the crystal. It was impossible to obtain any measurements of the angles owing to the smallness of the crystals and the roughness of the faces. The value, therefore, of the hemipyramid indices is unknown. The faces ‘““a”’? are 100 (Miller) or aa (Naumann), whilst the faces “‘c” are the negative hemipyramid —/kl (Miller) or —mP (Naumann). They cleave parallel to the ortho-pinacoid distinctly. Examined in polarised light they exhibit depolarisation, on rotating the Nicol’s prism the colour changing from a light-yellow to a rich brownish- red. On determining the Number of Micro-organisms in Air. 455 «A new Method of determining the Number of Micro- organisms in Air.” By THOMAS CARNELLEY, D.Sc., Pro- fessor of Chemistry, and THos. WILSON, University Coilege, Dundee. Communicated by Sir Henry Roscog, F.R.S. Received February 3—Read February 16, 1888. The subject of bacteriology has of late excited considerable interest, and is at present studied by a great number of investigators, both in _ this country and on the Continent. Under these circumstances a new and improved method for the bacterioscopic analysis of air will be of nterest. There are several methods a present in use for this purpose, but it will only be necessary to refer to two of these, in both of which solid media are employed. 1. Hesse’s Methed (‘ Mittheilungen aus dem Kaiserlichen Gesund- heitsamte,’ vol. 2, p. 182).—This is the oldest process in which a solid medium is used for the nutrition of the micro-organisms, and is _ the one which has been most commonly employed. The principle of the process consists in drawing a known volume of air through a long wide tube, the inside of which is coated with Koch’s nutrient gela- tine-peptone. As the air passes through the tube the micro-organisms settle on the jelly, and in the course of a few days develop into zooglea or colonies, and thus become visible to the naked eye and may _be counted. 2. Dr. Percy Frankland’s Method (‘ Roy. Soe. Proc.,’ vol. 41, p. 443 ; ‘Phil. Trans.,’ B, vol. 178 (1887), p. 113)—This method connate essentially in aspirating a known volume of air through a small glass tube containing two sterile plugs consisting either of glass-wool alone or of glass-wool coated with sugar. After a given volume of air has been aspirated the two plugs are transferred respectively to two flasks each containing melted sterile gelatine-peptone and plugged with sterile cotton-wool stoppers. The plug is carefully agitated with the jelly so as to avoid any formation of froth, and when the plug has been completely disintegrated and mixed with the gelatine the latter is congealed so as to form an even film over the inner surface of the flask. On incubating these flasks at a temperature of 20° C., the colonies soon begin to appear and may be counted. New Method.—The new process which forms the subject of the _ present communication is a modification of Hesse’s method, in which a flask is substituted for a tube. The flask employed is conical in form and has a capacity of about half a litre. The flask is fitted with a two-holed india-rubber stopper. Through one hole passes the “‘entrance tube” AA. This is a piece VOL. XLIY. 22% Hi A56 Dr. T. Carnelley and Mr. T. Wilson. of glass tube about 8 inches long and 2 inch* internal diameter. Ti extends about two-thirds of the way down the flask, and is closed at the outer end by a glass stopper B, fitted on with a piece of india-rubber tubing. Into the other hole of the stopper is fitted the “exit tube ” CC. This is simply a piece of ordinary glass tubing (about 3 inch Hig. 4. diameter) bent round at the lower end so that it opens in the neck of the flask just under the india-rubber stopper. It is open at both ends, but contains two cotton-wool plugs to prevent any micro- organisms passing back into the flask from the outside air. 10 c.c. of Koch’s gelatine-peptone are introduced into the flask and the stopper tied on with copper wire. The flask is then sterilised by heating in steam at.100° C. for an hour and allowed to cool, whereby * The entrance tube must have at least this width, for if it be too narrow, mois- ture from the jelly forms during sterilisation on the inside of the tube, and on cooling runs down and collects as a drop on the end, so that the air, on entering the flask, has to pass through this drop of water, which thus retains some of the micro- organisms, and so vitiates the results. This, however, is entirely obviated by using a tube of the prescribed width. On determining the Number of Micro-organisms in Air. 457 an even layer of gelatine solidifies at the bottom of the flask. On taking the flask out of the steriliser it is generally necessary to care- fully rinse the jelly round the sides of the flask so as to take up any steam which may have condensed there and which might subsequently collect in drops and run down on to the colonies and inoculate the rest of the jeliy. In doing this care should be taken to avoid frothing of the jelly. In taking a sample of air the aspirator is attached to the exit- tube C, and the india-rubber tube and stopper B removed from the end of A. A known volume of air is then drawn through the flask, after which the stopper is replaced. As the air passes through the flask the micro-organisms settle on the jelly, and in the course of a few days develop into colonies and may be counted. If there are a large number of micro-organisms present the bottom of the flask may, for convenience in counting, be marked out into squares with ink. The rate of aspiration we have employed is the same as in Hesse’s process, viz., about 1 litre in three minutes. Usually the micro- organisms are deposited more or less directly under the lower end of the entrance tube, while none are deposited on the sides of the flask, even though the latter be coated with jelly, which would seem to indicate that no micro-organisms pass over into the exit tube. At first sight it seemed very likely that on account of the air having to pass through an entrance tube 8 inches long, a number of the micro-organisms might adhere to the side of the tube and never reach the jelly, so that the results obtained would be too low. ‘In order to - ascertain whether this was the case or not, a number of flasks were prepared in which the inside of the entrance tube was coated with a thin layer of jelly. The samples of air were then taken in the usual way, and after sufficient time had been allowed for the development of the colonies, the number in the flask and in the entrance tube were counted, with the following results :— Table I. . Vol. of air No. of colonies | No. of colonies No. Circumstances. taken. in flask. in entrance tube. i) | Dusty air ...... 400 c.c. 287 3 2 Dusty ait ....~. 500 ,, 145 1 3 Dusty air ...... 500 ,, At least 100 4, Unfortunately we omitted to count the colonies in No. 3 for a day or two, when it was found that a number of them had run together, but there were at least 100, and probably many more. 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This apparent source of error, therefore, may be entirely neglected when the width of the entrance tube is not less than that prescribed. In order to test the quantitative accuracy of the method, a number of comparative experiments were made by collecting samples of air simultaneously in the flasks and in Hesse tubes, placed side by side. On p. 458 is a table of the results obtained in this way. In comparing these results it must not be forgotten that, even when two Hesse tubes are compared the one against the other, it is only occasionally that identical numbers are obtained in each tube. Thus one may get six in one tube and eight in the other, or twenty in one tube and twenty-three in the other, and so on, the difference varying according to the total number of micro-organisms present. From the above table it will be seen that in nearly all cases the number of micro-organisms (both bacteria and moulds) in the tube and in the flask correspond almost exactly. In Nos. 6, 7, 9, 15, 16, and 19, however, this is very far from being the case, for in each of these the flask method gave very much lower results than the Hesse tube. Of these six non-concordant experiments, four were made in outside air, and the other two in schoolrooms in which there was a considerable draught, for the day being warm, the windows and doors were all open. Now Dr. Percy Frankland (loc. cit.) has conclusively proved that -Hesse’s method does not give reliable results for outside air, except on calm days. He made a number of experiments in which a control tube was used side by side with the aspirated tube, and in this way he was able to obtain a rough idea of the number of micro-organisms which gain access to a Hesse tube, irrespective of aspiration. In illustration of this we may quote a few of his results :— Table Lil. : Vol. of air| Micro-organisms | Micro-organisms in | ad Pe ckyind. taken. /|in sopitatad tube. non-aspirated tube. | a aca Peas sree el oy ha. cap en iefoderate ........... 12 litres. 158 54. | Signi cs cee. cess | 12. 4, 12 3 3 | Moderately strong...| 12 ,, | 53 11 / 4 | Moderately strong...| 12 _,, 114 34 5 | Moderate, butvariable| 12 __,, 49 29 eremogerate ........-.| Ll |,, 52 15 ME MOUS sce ee ce vess | 10 ,, 75 15 BROOME sce ewes | DA | 78 48 Mee be hdir. ss seees | U2), 72 | 27 460 Dr. T. Carnelley and Mr. T. Wilson. From these experiments it is evident that Hesse’s method is not reliable for outside air, except when there is little or no wind. By reference to Table II it will be observed that, of the six experiments made in outside air only two were concordant, the discrepancy in the other four being very considerable. In order to learn if this discrepancy was due to the effect of the wind, the state of the latter was ascertained from the Observatory at the Dundee Harbour, for all the dates on which experiments had been made in outside air. The results were as follows :— Table IV. | | / Direction | Miles ae Micro- | No. of per | Wind as felt. Date. aster 8 organisms ‘ in Hesse : wind. hour. eri in flask. 2 S.W. 7 | Little or none. | April 22nd. 3 3 3 8. 53 | Little or none. | April 23rd. 13 12 | 7 | S.W.toS 6 | Might be gusty.| April 28th. AZ 14 9 | E.to N.E 11 Steady. May 2nd. 59 26 16 | W. toS.W 133 Gusty. May 19th. 60 11 19.) WW. 4-0, OW z Gusty. May 21st. 22 b) In the two cases in which the number of micro-organisms in the flask corresponded with that in the tube, little or no wind was felt, and the wind was travelling at the rate of about 6 miles per hour; whereas in the other four cases in which discordant results were obtained, the wind was travelling at an average of about 10 miles per hour, and was gusty besides. It would seem, therefore, that the flask method gives more correct resulls than Hesse tubes for cutside air when there is any aerial disturbance. The only two cases in which there was any discrepancy for inside air were Nos. 6 and 15. Both of these were samples of school air, and it was noted at the time the samples were taken that in both cases there was a considerable draught through the rooms, for the day being warm, the windows and doors were all open. On com- paring the determinations of carbonic acid made in these rooms at the same time, it was found that in both they were comparatively very low, viz., 10°6 vols. per 10,000 in No. 6, and 73 vols. in No. 15; whereas average school air in Dundee contains about 19 vols. of car- bonic acid per 10,000. This comparatively low amount of carbonic acid can only be accounted for by the fact that there must have been a draught in the room at the time the experiments were made. Experiments were also made in order to ascertain if any micro- On determining the Number of Micro-organisms in Air. 461 organisms gained entrance to the flasks irrespective of aspiration, corresponding experiments being made simultaneously with Hesse tubes. For this purpose a pair of flasks and a pair of Hesse tubes were simultaneously exposed to the outside air for the same length of time, but without aspirating air through any of them. The exit tube (which in an ordinary experiment is connected with the aspirator) of one of each pair of flasks and tubes was stoppered, and the exit tube of the other flask and tube left unstoppered. The entrance to each flask and tube was of course left open. The total number of colonies obtained in each case were as follows, the numbers in brackets being the number of moulds :— Table V. Hesse tubes. Flasks. Time No.| State of wind. of ex- osure. Un- Un- J PUSEPE ted: stoppered. Stopped. stoppered. 1 | Very strong......| % hour + 23 [1] te ee ae PGREM EON. w2 fe ee |b) 53 2 [2] heey 0 1) EMER ieee) nn... Ls 55 6 [5] kf 0 0 4 | Moderately stroug and variable....| 3 ,, 8 [6] 12 [5] a | 0 5 | Rather strong and | variable eee eee 3 ”» 8 lO] 12 [0] 0 I [0] 6 | Rather strong and | variable ..,.... & 3 45 [2 | 33 [1] 0 | 1 [0] Thus out of ten flasks exposed to the air for half to one hour, only three were contaminated, and these only very slightly, and on very windy days, whereas the Hesse tubes were considerably contami- nated. It is thus seen that the flask method, unlike the Hesse tube method, is practically free from vitiation by aerial disturbance. We can fully confirm Dr. P. Frankland’s statement that Hesse’s method gives good results in cases where the air is still and free from draughts, as in most inside buildings and outside on calm still days, for under these conditions Hesse’s method agrees remarkably well both with Frankland’s process and with our own; whereas in a dis- turbed atmosphere, as in outside air on windy days, or in buildings where a strong draught prevails, Hesse’s method gives results which are considerably in excess of those obtained either by Frankland’s method or by our own. The following are the chief advantages of the new method :— (1.) It possesses, in common with Hesse’s and Frankland’s processes, the advantages of a solid nutrient medium. 462 Dr. T. Carnelley and Mr. T. Wilson. (2.) It gives accurate results, as shown by comparative tests. (3.) There is no risk of aerial contamination either during the preparation of the flasks previous to use, or subsequently during the growth of the colonies. (4.) It is very much cheaper than Hesse’s method, for a flask fitted ready for use costs only about ls. 3d. (exclusive of jelly), where a Hesse’s tube costs about 3s. This is a very material item when a large number of experiments are to be made. (5.) The flasks being of thin glass very rarely break during sterili- sation, whereas this is a serious source of annoyance and expense in the case of Hesse’s tubes. (6.) There is not the least chance of leakage during sterilisation, as sometimes occurs with Hesse’s tubes, for in the latter method the india-rubber caps have to be very carefully fitted on, since with the slightest crease in the india-rubber the tubes are sure to leak during sterilisation, with consequent loss of jelly, which entails refitting and refilling. (7.) There is a great saving in jelly. A flask needs only 10 c.c., or one-fifth the quantity required by a Hesse tube. In a long series of experiments the cost of jelly is very considerable, both in the expense of the materials and the time required to make it. (8.) In common with Frankland’s process the flask method is free from errors arising from ‘aerial currents,’ which are sometimes so serious a source of error in Hesse’s tubes when employed for deter- minations in outside air, such currents being apt to blow micro- organisms into a Hesse tube over and above those contained in the volume of air aspirated. (9.) An advantage which the flask method possesses over Frank- land’s process is that in the former the micro-organisms pass directly on to the nutrient jelly in the flask, whereas in the latter they are first entangled in the glass-wool filter, and afterwards transferred to the cultivating medium, when they are disentangled from the glass-wool by agitation with the jelly, an operation which would seem to require considerable care. Again, in Frankland’s process the micro-organisms are embedded in the mass of the jelly, while in our method they fall and grow directly on the surface. | (10.) On the other hand Frankland’s method possesses two import- ant advantages ; first, on account of the small size of his filter tubes, they admit of being carried from place to place without inconvenience, whereas flasks and Hesse tubes are comparatively bulky. This is a great point when a large number of determinations are to be made at different places away from the laboratory. Second, the air can be aspirated through one of Frankland’s filters about four times as fast as through a Hesse’s tube, which is of considerable advantage in the case of determinations in outside air, where at least 10 litres require , On determining the Number of Micro-organisms in Air. 463 to be aspirated, though it is of no consequence for the air of buildings where the aspiration of only one-half, or at most 1 litre of air is necessary, and occupies less thantwo minutes. The rate of aspiration we have employed with our own method has been the same as with Hesse tubes, viz., 1 litre in three minutes. It is not at all unlikely, however, that a more rapid rate might be adopted without affecting the accuracy of the results. Addendum. Received April 22, 1888. The following experiments were made for the purpose of testing whether any micro-organisms pass into the exit tube or become attached to the under side of the cork. A. As regards the Passage of Organisms into the Exit Tube. In these experiments, the flask was fitted up and charged with jelly in the ordinary manner, except that a little jelly was also placed in the bend of the exit tube. The whole was then sterilised as usual, and, during the subsequent cooling, the flask was so manipulated that _a coating of jelly was formed over the inside walls of the exit tube, keeping clear, however, of the cotton-wool plugs. Half a litre of air was then drawn through each flask at the rate of 1 litre in three minutes. The samples were collected in a room in which a slight dust had been raised by the shaking of a door-mat. After the lapse of eight days, the number of colonies counted in each flask was as follows. In no case were any colonies found in the exit tube. Per 3 litre of air. ' | | | In exit In flask. | a Experiment I .. | About 300 | 0 Collected just after raising | of dust. Experiment II... About 200 | 0 Collected after a few mi- nutes’ interval. Experiment IIT..| About 250 | 0 Collected after a few mi- / nutes’ interval. Experiment IV .. | About 180 ) 0 Collected after a further in- ' terval of a few minutes. B. As regards the Attachment of Organisms to the Under Side of the , Cork. The flasks were charged and sterilised in the ordinary way, but during cooling, after sterilisation, the flask was so manipulated as to 464 On determining the Number of Micro-organisms in Air. allow the jelly to form a thin coating over the under side of the cork. Half a litre of air was then drawn through each flask at the rate of 1 litre in three minutes. The samples were collected as before, except that the dust raised was not nearly so great. After nine days, the following number of colonies had developed on the jelly in the flasks, but not a single one was observed on the under side of the cork :— Per 3 litre of air. In flask. On cork. Experiment I .. 57 0 Collected just after raising of dust. Experiment II .. 23 0 ~ | Collected after an interval of a few minutes. The above results show, therefore, that, with an aspiration of 1 litre of air in three minutes, all the organisms are deposited on the jelly at the bottom of the flask, and that none reach the cork or exit tube. This result is probably due not only to the action of gravity, but also to the initial velocity, with which the organisms leave the mouth of the entrance tube and enter the flask, being such as to project them on to the surface of the jelly at the bottom of the flask, where they stick and have not the chance of rising again. OBITUARY NOTICES OF FELLOWS DECEASED, Cuartes Ropert Darwin was the fifth child and second son of Robert Waring Darwin and Susannah Wedgwood, and was born on the 12th February, 1809, at Shrewsbury, where his father was a physician in large practice. Mrs. Robert Darwin died when her son Charles was only eight years old, and he hardly remembered her. A daughter of the famous Josiah Wedgwood, who created a new branch of the potter’s art, and established the great works of Etruria, could hardly fail to transmit important mental and moral qualities to her children ; and there is a solitary record of her direct influence in the story told by a school- fellow, who remembers Charles Darwin “ bringing a flower to school, and saying that his mother had taught him how, by looking at the inside of the blossom, the name of the plant could be discovered.” (Lp. 28.) The theory that men of genius derive their qualities from their mothers, however, can hardly derive support from Charles Darwin’s case, in the face of the patent influence of his paternal forefathers. Dr. Darwin, indeed, though a man of marked individuality of charac- ter, a quick and acute observer, with much practical sagacity, is said not to have had a scientific mind. But when his son adds that his father “‘formed a theory for almost everything that occurred ” (I, p. 20), he indicates a highly probable source for that inability to refrain from forming an hypothesis on every subject which he con- fesses to be one of the leading characteristics of his own mind, some pages further on (I, p. 103). Dr. R. W. Darwin, again, was the third son of Erasmus Darwin, also a physician of great repute, who shared the intimacy of Watt and Priestley, and was widely known as the author of ‘Zoonomia,’ and other voluminons poetical and prose works which had a great vogue in the latter half of the eighteenth century. The celebrity which they enjoyed was in part due to the attractive style (at least according to the taste of that day) in which the author’s extensive, though not very profound, acquaintance with natural phenomena was set forth; but in a still greater degree, probably, to the boldness of the speculative views, always ingenious and sometimes fantastic, in which he indulged. The conception of evolution set afoot by De Maillet and others, in the - early part of the century, not only found a vigorous champion in _ * The references throughout this notice are to the ‘ Life and Letters,’ unless the contrary is expressly stated, VOL. XLIV. 6 i Erasmus Darwin ; but he propounded an hypothesis as to the manner in which the species of animals and plants have acquired their characters, which is identical in principle with that subsequently rendered famous by Lamarck. | That Charles Darwin’s chief intellectual inheritance came to him trom the paternal side then, is hardly doubtful. But there is nothing to show that he was, to any sensible extent, directly influenced by his grandfather's biological work. He tells us that a perusal of the ‘Zoonomia’ in early lite produced no effect upon him, although he greatly admired it—and that on reading it again, ten or fifteen years afterwards, he was much disappointed, “the proportion of speculation being so large to the facts given.”’ But with his usual anxious candour he adds, ‘“‘ Nevertheless, it is probable that the hear- ing, rather early in life, such views maintained and praised, may have favoured my upholding them, in a different form, in my ‘ Origin of Species.’” (1, p. 38.) Erasmus Darwin was in fact an anticipator of Lamarck, and not of Charles Darwin; there is no trace in his works of the conceptions by the addition of which his grandson metamorphosed the theory of evolution as applied to living things and gave it a new foundation. Charles Darwin’s childhood and youth afforded no intimation that he would be, or do, anything out of the common run. In fact, the prognostications of the educational authorities into whose hands he first fell, were most distinctly unfavourable; and they counted the only boy of original genius who is known to have come under their hands as no better than a dunce. The history of the educational experiments to which Darwin was subjected is curious, and not with- out a moral for the present generation. There were four of them, and three were failures. Yet it cannot be said that the materials on which the pedagogic powers operated were other than good. In his boyhood, Darwin was strong, well-grown, and active, taking the keen delight in field sports and in every description of hard physical exercise which is natural to an English country-bred lad; and, in respect of things of the mind, he was neither apathetic, nor idle, nor one-sided. The ‘ Autobiography’ tells us that he “ had much zeal for whatever interested’’ him, and he was interested in many and very diverse topics. He could work hard, and liked a complex subject better than an easy one. The “clear geometrical proofs ’’ of Euclid delighted him. His interest in practical chemistry, carried out in an extem- porised laboratory, in which he was permitted to assist by his elder brother, kept him late at work, and earned him the nickname of ‘““oas”’ among his schoolfellows. And there could have been no ins sensibility to literature in one who, as a boy, could sit for hours reading Shakespeare, Milton, Scott, and Byron; who greatly admired some of the Odes of Horace; and who, in later years, on board the ii “Beagle,” when only one book could be carried on an expedition, chose a volume of Milton for his companion. Industry, intellectual interests, the capacity for taking pleasure in deductive reasoning, in observation, in experiment, no less than in the highest works of imagination: where these qualities are present any rational system of education should surely be able to make some- thing of them. Unfortunately for Darwin, the Shrewsbury Gram- mar School, though good of its kind, was an institution of a type universally prevalent in this country half a century ago, and by no means extinct at the present day. The education given was ‘strictly classical,” “ especial attention ” being “paid to verse-making,” while all other subjects, except a little ancient geography and history, were ‘ ignored. Whether, as in some famous English schools at that date and much later, elementary arithmetic was also left out of sight does not appear; but the instruction in Euclid which gave Charles Darwin so much satisfaction was certainly supplied by a private tutor. That a- boy, even in his leisure hours, should permit himself to be interested in any but book-learning seems to have been regarded as little better than an outrage by the head master, who thought it his duty to administer a public rebuke to young Darwin for wasting his time on such a contemptible subject as chemistry. English composition and literature, modern languages, modern history, modern geography, appear to have been considered to be as despicable as chemistry. For seven long years, Darwin got through his appointed tasks ; construed without cribs, learned by rote whatever was demanded, and concocted his verses in approved schoolboy fashion. And the result, as it appeared to his mature judgment, was simply negative. “The school as a means of education to me was simply a blank.”’ (1, p. 32.) On the other hand, the extraneous chemical exercises, which the head master treated so contumeliously, are gratefully spoken of as the “best part” of his education while at school. Such is the judgment of the scholar on the school; as might be expected, it has its counterpart in the judgment of the school on the scholar. The collective intelligence of the staff of Shrewsbury School could find nothing but dull mediocrity in Charles Darwin. The mind that found satisfaction in knowledge, but very little in mere learning, that could appreciate literature, but had no particular aptitude for grammatical exercises, appeared to the “ strictly classical” pedagogue to be no mind at all. As a matter of fact, Darwin’s school education left him ignorant of almost all the things which it would have been well for him to know, and untrained in all the things it would have been useful for him to be able to do, in after life. Drawing, practice in English composition, and instruction in the elements of the physical sciences, would not only have been infinitely valuable to him in reference to his future career, but would have furnished b 2 iv the discipline suited to his faculties, whatever that career might be. ‘And a knowledge of French and German, especially the latter, would have removed from his path obstacles which he never fully overcame. Thus, starved and stunted on the intellectual side, it is not sur- prising that Charles Darwin’s energies were directed towards athletic amusements and sport, to such an extent, that even his kind and sagacious father could be exasperated into telling him that “ he cared: for nothing but shooting, dogs, and rat-catching.” (I, p. 32.) It would be unfair to expect even the wisest of fathers to have foreseen that the shooting and the rat-catching, as training in the ways of quick observation and in physical endurance, would prove more valu- able than the construing and verse-making to his son, whose attempt, at a later period of his life, to persuade himself “that shooting was almost an intellectual employment: it required so much skill to judge where to find most game, and to hunt the dogs well”’ (1, p. 43), was by no means so sophistical as he seems to have been ready to admit. In 1825, Dr. Darwin came to the very just conclusion that his son Charles would do no good by remaining at Shrewsbury School, and sent him to join his elder brother Erasmus, who was studying medicine at Edinburgh, with the intention that the younger son should also become a medical practitioner. Both sons, however, were well aware that their inheritance would relieve them from the urgency of the struggle for existence which most professional men have to face, and they seem to have allowed their tastes, rather than the medical curriculum, to have guided their studies. Erasmus Darwin was debarred by constant ill-health from seeking the public distinction which his high intelligence and extensive knowledge would, under ordinary circumstances, have insured. He took no great interest in biological subjects, but his companionship must have had its influence on his brother. Still more was exerted by friends like Coldstream and Grant, both subsequently well-known zoologists (and the latter an enthusiastic Lamarckian), by whom Darwin was induced to interest himself in marine zoology. A notice of the ciliated germs of Flustra, communicated to the Plinian Society in 1826, was the first fruits of Darwin’s half century of scientic work. Occasional attendance at the Wernerian Society brought him into relation with that excellent ornithologist the elder Macgillivray, and enabled him to see and hear Audubon. Moreover, he got lessons in bird-stuffing from a negro, who had accompanied the eccentric traveller Waterton in his wanderings, before settling in Edinburgh. No doubt Darwin picked up a great deal of valuable knowledge during his two years’ residence in Scotland; but it is equally clear that next to none of it came through the regular channels of academic education, Indeed, the influence of the Edinburgh professoriate ¥v appears to have been mainly negative, and in some cases deterrent; creating in his mind, not only a very low estimate of the value of lectures, but an antipathy to the subjects which had been the occasion of the boredom inflicted upon him by their instrumentality. With the exception of Hope, the Professor of Chemistry, Darwin found them all “intolerably dull.’ Forty years afterwards he writes of the lectures of the Professor of Materia Medica that they were “fearful to remember.” The Professor of Anatomy made his lectures “as dull as he was himself,” and he must have been very dull to have wrung from his victim the sharpest personal remark recorded as his. But the climax seems to have been attained by the Professor of Geology and Zoology, whose prelections were so “ incredibly dull” that they produced in their hearer the somewhat rash determination never “‘to read a book on geology or in any way to study the science ” so long as he lived. (I, p. 41.) There is much reason to believe that the lectures in question were eminently qualified to produce the impression which they made; and there can be litile doubt, that Darwin’s conclusion that his time was better employed in reading than in listening to such lectures was a sound one. But it was particularly unfortunate that the personal and professorial dulness of the Professor of Anatomy, combined with Darwin’s sensitiveness to the disagreeable concomitants of anatomical work, drove him away from the dissecting room. In after life, he justly recognised that this was an “‘irremediable evil” in reference to the pursuits he eventually adopted ; indeed, it is marvellous that he succeeded in making up for his lack of anatomical discipline, so far as his work on the Cirripedes shows he did. And the neglect of anatomy had the further unfortunate result that it excluded him from the best opportunity of bringing himself into direct contact with the facts of nature which the University had to offer. In those days, almost the only practical scientific work accessible to students was anatomical, and the only laboratory at their disposal the dissecting room. We may now console ourselves with the reflection that the partial evil was the general good. Darwin had already shown an aptitude for practical medicine (1, p. 37); and his subsequent career proved that he had the making of an excellent anatomist. Thus, though his horror of operations would probably have shut him off from surgery, there was nothing to prevent him (any more than the same peculiarity prevented his father) from passing successfully through the medical curriculum and becoming, like his father and grandfather, a successful physician, in which case ‘ The Origin of Species’ would not have been written. Darwin has jestingly alluded to the fact that the shape of his nose (to which Captain Fitzroy objected), nearly prevented his embarkation in the “‘ Beagle’; it may be that the sensitiveness of that organ secured him for science. | Vi At the end of two years’ residence in Edinburgh, it hardly needed’ Dr. Darwin’s sagacity to conclude that a young man, who found nothing but dulness in professorial lucubrations, could not bring himself to endure a dissecting room, fled from operations, and did not need a profession as a means of livelihood, was hardly likely to distinguish himself as a student of medicine. He therefore made a new suggestion, proposing that his son should enter an English University and qualify for the ministry of the Church. Charles Darwin found the proposal agreeable, none the less, probably, that a good deal of natural history and a little shooting were by no means held, at that time, to be incompatible with the conscientious performance of the duties of a country clergyman. But it is char- acteristic of the man, that he asked time for consideration, in order that he might satisfy himself that he could sign the Thirty-nine Articles with a clear conscience. However, the study of “ Pearson on the Creeds’’ and a few other books of divinity soon assured him that his religious opinions left nothing to be desired on the score of orthodoxy, and he acceded to his father’s proposition. The English University selected was Cambridge; but an unexpected. obstacle arose from the fact that, within the two years which had elapsed since the young man who had enjoyed seven years of the benefit of a strictly classical education had left school, he had forgotten almost everything he had learned there, ‘‘ even to some few of the Greek letters.” (I, p. 46.) Three months with a tutor, however, brought him back to the pomt of translating Homer and the Greek Testament ‘with moderate facility,’ and Charles Darwin commenced the third educational experiment of which he was the subject, and was entered on the books ef Christ’s College in October 1827. So far as the direct results of the academic training thus received are concerned, the English University was not more successful than the Scottish. “ During the three years which I spent at Cambridge my time was wasted, as far as the academical studies were concerned, as completely as at Edinburgh and as at school.” (I, p. 46.) And yet, as before, there is ample evidence that this negative result cannot be put down to any native defect on the part of the scholar. Idle and dull young men, or even young men who being neither idle nor dull, are incapable of caring for anything but some hobby, do not devote themselves to the thorough study of Paley’s ‘Moral Philosophy,’ and ‘ Evidences of Christianity ’; nor are their reminiscences of this particular portion of their studies expressed in terms such as the following: ‘‘ The logic of this book. [the ‘Evidences ’] and, as I may add, of his ‘ Natural Theology’ gave me as much delight as did Euclid.” (1,'p. 47.) The collector’s instinct, strong in Darwin from his childhood, as is usually the case in great naturalists, turned itself in the direction of Insects during his residence at Cambridge. In childhood, it had been Vil damped by the moral scruples of a sister, as to the propriety of catching and killing insects for the mere sake of possessing them, but now it broke out afresh, and Darwin became an enthusiastic beetle collector. Oddly enough he took no scientific interest in beetles, not even troubling himself to make out their names; his delight lay in the capture of a species which turned out to be rare or hew, and still more in finding his name, as captor, recorded in print. Hvidently, this beetle-hunting hobby had little to, do with science, but was mainly a new phase of the old and undiminished love of sport. In the intervals of beetle-catching, when shooting and hunt- ing were not to be had, riding across country answered the purpose. These tastes naturally threw the young undergraduate among a set of men who prefered hard riding to hard reading, and wasted the mid- night oil upon other pursuits than that of academic distinction. A superficial observer might have had some grounds to fear that Dr. Darwin’s wrathful prognosis might yet be veritied. But if the eminently social tendencies of a vigorous and genial nature sought an outlet among a set of jovial sporting friends, there were other and no less strong proclivities which brought him into relation with associates of a-very different stamp. - Though almost without ear and with a very defective memory for music, Darwin was so strongly and pleasurably affected by it that he became a member of a musical society ; and an equal lack of natural capacity for drawing did not prevent him from studying goed works of art with much care. _ An acquaintance with even the rudiments of physical science was no part of the requirements for the ordinary Cambridge degree. But there were’ professors both of Geology and of Botany whose lectures were accessible to those who chose toattend them. The occupants of these chairs, in Darwin’s time, were eminent men and also admirable lecturers in their widely different styles. The horror of geological © lectures which Darwin had acquired at Edinburgh, unfortunately prevented him from going within reach of the fervid eloquence of Sedgwick; but he attended the botanical course, and though he paid no serious attention to the subject, he took great delight in the country excursions, which Henslow so well knew how to make both pleasant and instructive. The Botanical Professor was, in fact, a man of rare character and singularly extensive acquirements in all branches of natural history. It was his greatest pleasure to place his stores of knowledge at the disposal of the young men who gathered about him, and who found in him, not merely an encyclo- pedic teacher but a wise counseller, and, in case of worthiness, a warm friend, Darwin’s acquaintance with him soon ripened into a friend- ship which was terminated only by Henslow’s death in 1861, when his quondam pupil gave touching expression to his sense of what he - vill owed to one whom he calls (in one of his letters) his “dear old master in Natural History.” (II, p. 217.) It was by Henslow’s advice that Darwin was led to break the vow he had registered against making an acquaintance with geology; and it was through Henslow’s good offices with Sedgwick that he obtained the oppor- tunity of accompanying the Geological Professor on one of his excursions in Wales. He then received a certain amount of practical instruction in Geology, the value of which he subsequently warmly acknowledged. (I, p. 237.) In another direction, Henslow did him an immense, though not altogether intentional service, by recom- mending him to buy and study the recently published first volume of Lyell’s ‘ Principles.’ As an orthodox geologist of the then dominant catastrophic school, Henslow accompanied his recommendation with the admonition on no account to adopt Lyell’s general views. But the warning fell on deaf ears, and it is hardly too much to say that Darwin’s greatest work is the outcome of the unflinching application _to Biology of the leading idea and the method applied in the ‘ Prin- ciples’ to Geology.* Finally, it was through Henslow, and at his suggestion, that Darwin was offered the appointment to the “ Beagle” as naturalist. During the latter part of Darwin’s sonidess at Cambridge the prospect of entering the Church, though the plan was never formally renounced, seems to have grown very shadowy. Humboldt’s ‘Personal Narrative,’ and Herschel’s ‘ Introduction to the Study of Natural Philosophy,’ fell in his way and revealed to him his real vocation. The impression made by the former work was very strong. ‘““My whole course of life,’ says Darwin im sending a message to Humboldt, “is due to having read and re-read, as a youth, his personal narrative.” (I, p. 336.) The description of Teneriffe inspired Darwin with such a strong desire to visit the island, that he took some steps towards going there—inquiring about ships, and. SO on. : But, while this project was fermenting, Henslow, who had been asked to recommend a naturalist for Captain Fitzroy’s projected ex- pedition, at once thought of his pupil. In his letter of the 24th August, 1831, he says: ‘‘I have stated that I consider you to be the best qualified person I know of who is likely to undertake such a situation. I state this—not on the supposition of your being a finished naturalist, but as amply qualified for collecting, observing, and noting anything worthy to be noted in Natural History . . . . The voyage is io * “ After my return to England it appeared to me that by following the example of Lyell in Geology, and by collecting all facts which bore in any way on the varia- tion of animals and plants under domestication and nature, some light might perhaps be thrown on the whole subject [of the origin of species].’’ (I, p. 83.) See also - the dedication of the second edition of the ‘Journal of a Naturalist.’ ix last two years, and if you take plenty of books with you, anything you please may be done.”’ (I, p.193.) The state of the case could not have been better put. Assuredly the young naturalist’s theoretical and practical scientific training had gone no further than might suffice for the outfit of an intelligent collector and notetaker. He was fully conscious of the fact, and his ambition hardly rose above the hope that he should bring back materials for the scientific “lions”? at home of sufficient excellence to prevent them front turning and rending him. (I, p. 248.) But a fourth educational experiment was to be tried. This time Nature took him in hand herself and showed him the way by which, to borrow Henslow’s prophetic phrase, “anything he pleased might be done.” _ The conditions of life pibsontad by a ship-of-war of only 242 tons burthen, would not, prima facie, appear to be so favourable to intellec- tual development as those offered by the cloistered retirement of Christ’s College. Darwin had not even a cabin to himself; while, in addition to the hindrances and interruptions incidental to sea-life, which can be appreciated only by those who have had experience of _ them, sea-sickness came on whenever the little ship was “lively”; and, considering the circumstances of the cruise, that must have been her normal state. Nevertheless, Darwin found on board the “ Beagle” that which neither the pedagogues of Shrewsbury, nor the profes- soriate of Edinburgh, nor the tutors of Cambridge had managed to give him. ‘I have always felt that I owe to the voyage the first real training or education of my mind (I, p.61);” and im a letter, written as he was leaving England, he calls the voyage on which he was starting, with just insight, his ‘second life.” (I, p. 214.) Happily for Darwin’s education, the school-time of the ‘“‘ Beagle” lasted five years instead of two; and the countries which the ship visited were singularly well fitted to provide him with object-iessons on the nature of things of the greatest value. While at sea, he diligently collected, studied, and made copious notes upon the surface Fauna. But with no previous training in dissection, hardly any power of drawing, and next to no knowledge of comparative anatomy, his occupation with work of this kind— notwithstanding all his zeal and industry—resulted, for the most part, in a vast accumulation of useless manuscript. Some acquaintance with the marine Crustacea, observations on Planaric and on the ubiquitous Sagitta, seem to have been the chief results of a great amount of labour in this direction. It was otherwise with the terrestrial phenomena which came under the voyager’s notice: and Geology very soon took her revenge for the scorn which the much-bored Kdinburgh student had poured upon her. Three weeks after leaving England the ship touched land for the it first time at St. Jago, in the Cape de Verd Islands, and Darwin found his attention vividly engaged by the voleanic phenomena and the signs of upheaval which the island presented. His geological studies had already indicated the direction in which a great deal might be done, beyond collecting; and it was while sitting beneath a low lava cliff on the shore of this island, that a sense of his real capability first dawned upon Darwin, and prompted the ambition to write a book on the geology of the various countries visited. (I, p. 66.) Hven at this early date, Darwin must have thought much on geological topics, for he was already convinced of the superiority of Lyell’s views to those entertained by the catastro- phists*; and his subsequent study of the tertiary deposits and of the terraced gravel beds of South America was eminently fitted to strengthen that conviction. The letters from South America contain little reference to any scientific topic except geology; and even the theory of the formation of coral reefs was prompted by the evidence of extensive and gradual changes of level afforded by the geology of South America; ‘‘No other work of mine,” he says, “‘was begun in so deductive a spirit as this; for the whole theory was thought out on the West Coast of South America, before I had seen a true coral reef. 1 had, therefore, only to verify and extend my views by a careful examination of living reefs.” (I, p. 70.) in 1835, when starting from Lima for the Galapagos, he recommends his friend, W. D. Fox, to take up geology :—“‘ there is so much larger a field for thought than in the other branches of Natural History. I am become a zealous disciple of Mr. Lyell’s views, as made known in his admirable book. Geologising in South America, I am tempted to carry parts to a greater extent even than he does. Geology is a capital science to begin with, as it requires nothing but a little read- ing, thinking, and hammering.” (I, p. 263.) The truth of the last statement, when it was written, is a curious mark of the subsequent progress of geology. Even so late as 1836, Darwin speaks of being ‘“‘much more inclined for geology than the other branches of Natural History.” (I, p. 275.) 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On the Electromotive Changes connected with the Beat of the Mesias : lian Heart, and of the Human Heart in particular. By ee D. WaLier, MED: : i : : : : ; vant: Rese ! IV. On the Plasticity of Glacier and other Iee. By James C, McCown, Pete a M.A., Fellow of Clare College, Cambridge, and Duptzy A. Kipp . V. On the Organisation of the Fossil Plants of the Coal-measures. aaa \ Part XV. By W. C. Wixuiamson, LL.D., ERS, Aomteet of Botany i in the Owens College, Manchester . : sa Wao 8 VI. Effects of different Positive Metals, &c., upon. the Chiatizes of Potential , ee of Voltaic Couples. By G. Gorz, F.R.S. , : : - 368 VII. Magnetic Qualities of Nickel (Supplementary Paper). By J. pa as Ewine, F.R.S., Professor of Bngmeee in Uae College, os ae Dundee : 5 hes VIII. Evaporation and Dissociation. Part VIII. A Study of the Thermal _ Properties of Propyl Alcohol. By WiLL1AmM eon Ph. micas . re ; and SypNEY Youne, D.Sc. . . i : IX. Contributions to the Chemistry of Chilorophl No. IIL. By Takeo Scuunck, E.R.S. . 5 . uP mr X. On the Specific Resistance of Meuiae By R. 1. Guasseioan M. A y _E.R.S., Fellow of Trinity College, and T. C. Firzparricx, B.A., Fellow of Christ’s College, Demonstrators in the Cavendish Labora- tory, Cambridge ; ; : : 4 : : th a = XI. Researches on the Structure, Organisation, and Classifignene of tee Fossil Reptilia. VI. On the Anomodont mh and. their Allies. — By H.G. Seetzey, F.RS,. . 4. #4 XII. A new Form of Eudiometer. By WILLIAM wideas MD,, ERS. : (Plate 14) . g . . : i ¢ : ye os ecient ta ol) XIII. Theorems in Analytical Geometry. By W.H. L. Russert, F.RS. . | XIV. On the Determination of the Photometric Intensity of the Coronal. i Light during the Solar Eclipse of August 28-29, 1886. Preliminary Notice. By Captain W. pr W. Asyey, C. ay Biel ERS, and aie T. KE. Toorre, Ph.D., F.R.S. . a ‘ : uae ec ee XV. Seismometric Measurements of the Vibration of the Ngee Tay ee ; during the passing of Railway Trains. By J. A. 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