(./^^YV-^ "l^ C-O^JlyiS'-'^'^^H^/ '<^f\ tii FORTHE PEOPLE FOK EDVCATION FOR SCIENCE LIBRARY OF THE AMERICAN MUSEUM OF NATURAL HISTORY f7,i; Mi^rrL/i/ MEMOIRS AND PROCEEDINGS MANCHESTER LITERARY & PHILOSOPHICAL SOCIETY. (MANCHESTER MEMOIRS.) Volume LII. (1907-8 MANCHESTER 36, GEORGE STREET. 1908, ^C. /j(^<^o4^^^mif-fl9- NOTE. The authors of the several papers contained in this volume are themselves accountable for all the statements and reasonings which they have offered. In these par- ticulars the Society must not be considered as in any way responsible. CONTENTS. MEMOIRS. INAUGURAL ADDRP:SS. By the President, Professor H. B. Dixon, M.A., F.R.S. ... pp. i — 13 I. On the Atomic Weight of Radium. By Henry Wilde, D.Sc, D.C.L., F.R.S pp. 1—3 {Issued separately, November 21st, igoy). II. New Reactions for the Characterisation of Mercerised Cotton. By Julius HiJBNER, M.Sc.Tech., F.I. C pp. i — 4 (Issued separately, December iSth, igoy). III. The Cone of Bothrodendron iinindiiin (Will.) By D. M. S. Waison, B.Sc. With Plate and 2 Text-fiirttres ... pp. i — 16 (Issued separately , J anuar •jth, igoS.) IV. On the Ulodendroid Scar. By D. M. S. Watson, B.Sc. Plalcs I. — II., and Text-fiiiiire ... ... ... \)p. 1 — 14 (Isstied separately, Jaiiuary ytk, iQoS). V. On a new Phytophagous Mite, lohinaiinia iiisigiiis, Berl. var. dissi/iii/is n. var., with notes on other species of economic importance. By C. Gordon Hewitt, M.Sc. With Plate a>id 2 Text -figines ... ... ... pp. i — 10 (Issued separately, January, ijt/i, igoS). VI. Some Notes on the Mammals of Lundy. By T. A. Coward, F.Z.S.... pp. I — 14 (Issued separately, January 22nd, igoS). VII. The Atomic Weight of Chlorine. By E. C. Edgar, D.Sc pp. 1--2 (Issued separately, February Oih, jgoS). VIII. On a New Type of Dynamical Stability. By Andrew Stephenson. With 2 Text-Jigiires pp. i — 10 (Issued separately, March 14th, igoS). IX. A Method of Counting the Number of a-Particles from Radio-active Matter. By Professor E. Rutherford, F.R.S., and H. Geiger, Ph.D pp. 1—3 (Issued separately, March 14th, igoS) VI CONTENTS. ^ X. On the Physical Aspect of the Atomic Theory. (The Wilde Lecture.) By Professor J. Larmor, Sec. R.S. ... pp, I — 54 (Issued separately, March 25th, igoS). XI. Notes on the Greater Horseshoe Bat, Rhinolophiis ferrum- equinum (Schreber), in Captivity. By T. A. Coward, F.Z.S. With Plate. pp. i— 12 {Issued separately, April 21st, iqoS). XII. Action of Selenium and Tellurium on Arsine and Stibine. By P^RANCis Jones, M.Sc, F.R.S.E pp. 1—9 (Issued separately, April 22nd, JQ08). XIII. Report on the Recent Foraminifera from the Coast of the jlT^y .? / .^ / /- Island of Delos (Grecian Archipelago). Part V. By /' ','^(Jti ' Henry Sidebottom. Plates I. — V. pp. 1—28 ' (Issued separately, lilay 23rd, igoS). XIV. Some Observations on the Chemical Action of Tropical Sunlight. By Gilbert John Fowler, D.Sc, F.I. C. pp. i — 20 (Issued separately, June 4th, igoS). XV. An Annotated List of the Alien Plants of the Warrington District. By G. A. Dunlop pp. i — 27 (Issued separately, July 22iid, iqoS) PROCEEDINGS. Brothers, A. — On the Production of Photographs in the Colours of Nature xii — xiv Coward, H. F., M.Sc. — The Direct Combination of Carbon and Hydrogen ... ... ... ... ... x Coward, T. A., F.Z.S. — Exhibit of a living specimen of the Greater Horseshoe Bat {Rhinolophus ferrwn-equimwi) ... xii DixON, H. B., M.A., F.R.S. — Presentation to the Society's Library of works by Hon. Robert Boyle ... ... ... ... x — xi Reference to the death of Lord Kelvin ... ... ... ... xii Hoyle, W. E., D.Sc, F.R.S.E. — Exhibit of fossil insects from Shiobara, Japan... ... ... ... ... ... ... xvii CONTENTS. VU Jordan, F. W. — I'resentalion lo the Society of an engraved portrait of John Dalton, a lock of Dalton's hair, and an engraved portrait of Thomas Young ... ... .. ... ... ii Knecht, Edmund, Ph.D., M.Sc.Tech., F.I.C. Demonstration illustrating the formation of acetylene from elementary substances ... ... ... ... ... ... ... ix — x Note on the action of Oxalic Acid on Cellulose... ... xxii — xxiii McNicOL, Mary, M.Sc. — On Cavity Parenchyma and Tyloses in Ferns ... ... ... .. ... ... ... xvii — xviii Murray, Margaret A., F.S.A., Scot. — On the Mummy of Khnumu Nekht in the Manchester Museum ... ... ... xxviii — xxx Oldham, Charles, F.Z.S., M.B.O.U. — Field Notes on the Birds of the Ravenglass Gullery, 1906 .. ... ... ... xx OsBORN, T. G. B. — Discovery of a new locality for the fungus Natmatelia encephala (Fries) ... ... ... ... ... xi On a new variety of Ulex sp. ( Gallii? ) ... ... ... ... xxvii Pettigrew, Robert. — On the occurrence of Quartz Crystals in Limestone, Columnar Coal, Marlile, &c. ... ... xxi — xxii Pope, William J., F.R.S., and Barlow William, F.C.S., F.G.S. — The Relation between the Crystalline Form and the Chemical Constitution of Simple Inorganic Substances ... iii — v RUTHERKORi', Ernest, F.R.S. — The Production and Origin of Radium ... ... ... ... ... ... ... ... v — vii Snape, Nellie, B.Sc. — Spore formation in the Genus Chaetoceros xxvii — xxviii Thorp, Thomas, F.R.A.S. — Description of a simple means of pro- ducing the characteristic glow in exhausted tubes XXV Weiss, F. E., D.Sc, F.L.S.— Exhibit of the base of a stem of Erica arborea, and of fruits of an abnormal variety of CiVr^w wifi/zVfl, from the Riviera ... ... ... xxv — xxvi A new type of Stigmaria .,. ... ... ... ... ... xxviii General Meetings ... ... ... ... ii, v, vii, ix, xi, xiv, xv, xviii, xxvi Annual General Meeting ... ... xxiv j^ viii CONTENTS. • Special iMetning for the delivery of the Wilde Lecture ... ... xvi Keport of Council, 1908, with obituary notices of Sir B. Baker, K.C.M.G., F.K.S., Dr. Alexander Buchan, F.R.S., Lord Kelvin, O.M., G.C.V.O., F.R.S., Sir W. II. Parkin, F.R.S., Dr. E.J. Routh, F.R.S., Dr. IL C. Sorby, F.R.S., and Professor C. A. Young ... ... ... ... sxxi — Ivi Treasurer's Accounts ... ... ... ... ... ... ...Ivii — lix List of the Council and Members of the Society ... ... Ix — Ixxv List of the Awards of the Wilde and Dalton Medals and of the Premium... ... ... ... ... ... ... ... Ixxvi List of the Wilde Lectures ... ... ... ... ... Ixxvii — Ixxviii List of the Presidents of the Society ... ... .. .. Ixxix — Ixxx MiVicJiestcr Meuioirs, Vol. Hi. {igoj). INAUGURAL ADDRESS. By tlic President Professor H. B. DixoN, M.A., F.R.S. October ist^ ^907. Two years ago our late President made an innovation which has caused me some anxious moments of reflection. By my action, perhaps, it would be decided whether it shall be the custom for cur Society to demand of each new president an address, or whether we shall continue (as heretofore) unaddressed,and look on the late inaugura- tion as something extraordinary and not to be repeated ; regard it, in fact, as a somewhat dangerous overflow of mental activity — a sort of 'Spate' in the Highlands of literature and learning which form the happy hunting ground of my distinguished predecessor. But with the example of so many learned societies before me, and the happy precedent afforded by Sir W. Bailey, I thought, however inadequate my own share might be, that it would be to the advantage of our Society, if future Presidents gave us the benefit of their thoughts and experience. At the annual meetings of the British Association, it was long the custom for the President to attempt a survey of the whole domain covered by the advance of science during the year. As one well-known President put it — " he took advantage of the elevation of his position . . . and casting his eyes round the horizon of the scientific world, reported to them what could be seen from his watch-tower." But this custom has fallen into disuse. Extreme specialisation in each province of science made it impossible that even the British Association could secure a succession of presidents ready to report to October 2gt/i, igoy. 2 Dixon, Inaugural Address. * their colleagues on what was happening round the whole horizon ; and the modern president has usually spoken either of that portion of science familiar to him by his own work, or on that fruitful subject — the fate of the nation whose government, commerce, and education, are conducted by persons unchastened by research. The addresses of the Sectional Presidents, spoken to audiences of experts, have followed the lead of the Presidential address, and no longer attempt a survey of their respective sciences. I would propose, then, in virtue of the brief authority vested in me by the Society, in the first place to speak shortly on some of the work recently done in chemical science, and especially that on the properties and reactions of gases at high temperatures, and secondly to make a few remarks on the character of our own proceedings. The work on radio-activity has advanced chiefly on the lines of the disintegration theory, which has proved itself most valuable not only in suggesting the origin of radium itself, but in connecting together the series of substances arising from the spontaneous changes in the radio-elements. And if in the past we in Manchester have not taken the lead in radio-active researches, we can feel much confidence that no reproach on this score can be made against us in the future ; for to-night we most warmly welcome Professor Rutherford as a candidate for our membership. The birth-place of the Atomic Theory need feel no disintegrating shock. The laws of chemical combination, the gas laws, isomerism, stereo-chemistry and other generalisations demand the chemical molecule and the atom. We have not got rid of Dalton's atoms, we are beginning to see how wonderfully they are constructed ! Manchester Memoirs, Vol. /ii. {igoy). 3 Another property of the chemical atom, valency, has recently been shown by the brilliant work of Messrs. Barlow and Pope to be connected in a most definite manner with the volume of the region dominated by the atom in crystalline structures. Following up this discovery, Le Bas has shown that the " spheres of influence " of carbon and hj'drogen have the same volume throughout the whole series of solid normal paraffins — a remarkable confirmation of the theory. Professor Pope has brought before us a model of benzene, consisting of columns built up symmetrically of close-packed assem- blages of spheres of influence, the latter having volumes proportional to the valencies of the atoms — carbon and hydrogen. He cut a slice off the column and partitioned off a piece of this in a hollow mould, and lo ! a new "space" formula for the benzene molecule in which each hydrogen atom snuggled against three carbons, and each carbon atom touched three hydrogens. When we had got over the initial difficulty caused by the absence of bonds and our consequent wonder why the atoms stuck together, and when we saw that the isomerism of the benzene derivatives could be explained by this model as well as by the ordinary plane hexagon or by the wedge — we began to dimly recognise that we were in the presence of a great idea. In watching the manipulation of these close-packed assemblages 1 could not help recalling to mind Dalton's explanation of the reason why water expands when cooling from 4''C. to the freezing point. He pictured the ultimate particles of water with their ' atmospheres ' as spherical, and conceived them, at the maximum density, to be piled up layer on layer like a square pile of shot — where each sphere touches four others in the same plane and rests upon four others in the plane below. Then, says Dalton, if the square pile is distorted 4 Dixon, Inaugural Address. * into a rhombus, each layer has its particles in a more condensed form, but raises the layer above so that the pile is increased in height, and the number of particles in a given volume becomes less. We shall have now another answer to meet the sceptic's enquiry — " What do you know about your atom when it has combined with another?" I think it is a matter on which this Society may well feel pride that we were the first to hear this newest development of the atomic theory. My reference to benzene will naturally recall to many here that the hexagon or ring of benzene has no monopoly among closed carbon chains. The researches of our member. Professor Perkin, on the formation and stability of various carbon rings are known and admired by all organic chemists. Of late years he has been specially occupied with researches on the Camphor and Terpene series, and his work has been crowned by the discovery — specially dear to the constitutional chemist — of processes for the synthetical preparation of Camphor and of Terpene in the laboratory. It is not out of place to mention here that, founded on Dr. Perkin's theoretical researches, a successful technical process for the manu- facture of camphor from oil of turpentine has been developed in Manchester. Dr. Perkin and his pupils have also successfully investigated the exceedingly com- plex constitution of the natural colouring matters — Brazilin and Haematoxylin. This room is not, perhaps, the place for elaborate discussions on constitutional formulae, but I feel sure the Society would be glad if Dr. Perkin brought before us an outline of his dis- coveries— as he makes them. With regard to the work that I am most interested in ' Manchester Memoirs, Vol. lit. {igoj). 5 personally, M. Jouguet has recently published a series of elaborate mathematical memoirs on the propagation of the explosion-wave in gases. His data are taken from the work of Berthelot, Le Chatelier and my own. He tells us that we have made unjustifiable assumptions, and that we have proceeded by a sort of intuition rather than with the mathematic rigour necessary in such a research. I, for one, plead guilty. I may recall the fact that I found empirically that the rate of the explosion-wave in a number of gaseous mixtures was equal to the velocity of sound in the buvjiing gases assumed to be at a temperature double that of ordinary combustion. I did not of course mean to explain the explosion-wave as being itself a sound-wave produced in the gaseous products of com- bustion, i.e.^ a cause following its own effect ; and I thought I had sufficiently guarded myself by calling my formula ' an empirical expression ' which was found to be so far parallel to the truth that it might be useful as a " working hypothesis." I compared the explosion-wave to an intense compression-wave, propagated like a sound- wave by exchange of moinenta on molecular collisions, and maintaining its intensity by reason of the chemical reactions set up. For instance, in the explosion of electrolytic gas, I imagined a steam molecule just formed in the wave front communicating momentum by collision to an unburnt hydrogen or oxygen molecule, and this in turn combining when it met an unlike molecule. According to this view the chemical reaction does not take place between cold molecules but between molecules half of which have been heated by collision with the products of combustion. There is a most remarkable agreement between the velocities given by my formula and the measured rates of the explosion-wave in a number of gases ; and the use of this formula in the investigation 6 Dixon, huxugiiral Address. * of the mode in which carbon compounds burn at high temperature has, I think, been justified. But who has not had to suffer that great tragedy of Science, as Huxley- calls it, the slaying of a beautiful hypothesis by an ugly fact? In this case the increase of the specific heats of gases at high temperature is an ugly fact. I assumed it to be constant : my own experiments have convinced me that it is not. My formula, therefore, though parallel to the truth, is obviously not truth itself ! Again, I pointed out that the formula did not account for the curious fact that an increase in the initial temperature of the gases was accompanied by a diminu- tion in the rate of the explosion. M. Jouguet's formula, founded on Hugoniot's equation, does account for this diminution. M. Jouguet argues that the heated products of combustion follow the wave front with great velocity, and I have abundant photographic evidence that this is the case : he states that the explosion-wave travels with the velocity of sound through this rapidly moving gas, and therefore has an absolute velocity (relatively to the unburnt gas) of both motions added together. The important question remains, can we calculate backwards by Jouguet's equations from the easily-measured rates of explosion to the unknown specific heats ? M. Crussard * claims that this is an important new application. Apart from the consideration that Hugoniot's theory has not been experimentally established, I must point out that if we calculate backwards from the rates of explosion we get different values for the specific heats according as the condensation in the wave is assumed to be more or less. These values, however, lie between certain limits, and the method therefore promises to be useful. 1 must * L. Crussard, " Ondes de choc et onde explosive." Bull. Soc. de f Industrie Miniralc, Salni-Elleiine, 1907. Mandicster Memoirs, Vol. Hi. (1907). 7 also point out that there is nothing novel in M. Crussard's idea of working backwards from the explosion rate. One of our members, Mr, D. L. Chapman * has calculated the specific heats of gases from the explosion-rates by means of equations deduced from Riemann's formula for the propagation of a compression wave. Until lately no one had measured directly the specific heat of a gas at temperatures beyond 200"C. The un- expectedly low pressures found by Bunsen in the explosion of gases, were attributed by him to the dissociation of the products, by Berthelot and by Le Chatelier to the great rise in their specific heats. Either hypothesis would account for the observed pressures. Dugald Clerk added a third explanation — that the gases combined compara- tively slowly, and that heat was lost by conduction, etc., while the chemical combustion was still proceeding. The specific heats deduced from the pressure curves of exploded gases at high temperatures, did not appear on the pro- longation of the curves drawn, for instance, for CO2 or steam at low temperatures ; hence the doubt as to what happens at high temperatures, and the necessity for making determinations at intermediate temperatures. The specific heat of air was determined up to 900'^C. by a resonance method in an open tube by Stevens, but his results, which show a distinct rise, have been questioned by A. Kalahne,"!" who with an improved apparatus finds a much smaller increase. I have directly determined the specific heat of CO., by heating the compressed gas in a steel bomb and dropping it into a specially constructed calorimeter. The rise in the specific heat is undoubted, but the experiments * D. L. Chapman, "On the Rate of Explosion in Gases." Phil. Mag., Jan., 1899. t DriidSs A/ui., xi., 225. 8 Dixon, Inaugural Address. became difficult at 400° and the margin of safety was small. On the other hand the velocity of sound in CO2 can be measured in a heated tube and compared with that in air or nitrogen under the same conditions; by this method I have found the rise in specific heat of CO. up to 400° on the assumption that air has a constant value. This experiment gives the specific heat at 4oo°C., and not, as in the cooling method, the mean specific heat between 20° and 400X, Quite recently Holborn, at Charlottenburg, has succeeded in pushing Regnault's calorimeter method to high temperatures. I am glad to find that our curves for CO., run, as far as they go, nearly parallel with one another : — Specific Heats of CO., at constant pressure. At 0°. 100°. 200°. 300°. 400°. 600°. 800°. Holborn.. "203 ... '216 ... "228 ... ... "250 ... "268 ... "281 Dixon ... 'igd ... -208 ... "220 ... "232 ... "244 ... ... The rise in the specific heat from 0° to 100" agrees with the experiments of VVullner ; it is much less than that found in the old determinations of Regnault and of Wiedemann. The new values would "join up" fairly with the high temperature values deduced by Le Chatelier from the explosion pressures. Holborn, also, this sum- mer has determined the specific heat of steam, and shown that it rises regularly. Dugald Clerk, too, by an entirely different method, has shown the rise in the specific heats of gases in the gas-engine cylinder. There is, therefore, a satisfactory consensus of opinion as to the fact of the increase in the specific heats of the triatomic gases ; the rate of the rise has still to be deter- mined with precision. Another point connected with gases that has recently occupied attention is the temperature of their ignition points. The methods that have been used, mainly on the Manchester Memoirs, Vol. Hi. (1907). 9 continent, do not avoid an error inherent in the method of heating the mixed gases together — viz., the gradual combination of the gases as they are raised to the ignition point. To obviate this difficulty, Falk has recently ignited the mixture by sudden adiabatic compression in a steel cylinder — and calculated the temperature from the volume occupied at ignition. I think he could not avoid a local cooling of the gas in contact with the cold walls of the cylinder and piston, which would affect his calculated ignition points. Mr. Coward has lately been working with an apparatus I designed with the aid of Mr. G. W, A. Foster, and has obtained ignition points which vary through a comparatively small range of temperature. The method consists in bringing the combustible gas through a small tube passing along the axis of a large tube, electrically heated. When, five years ago, Dr. Edgar and I began to devise a method for burning a weighed quantity of hydrogen in a weighed quantity of chlorine, we thought our attempt — if it succeeded — would be regarded, at best, as an academic vindication of Stas' atomic weight. We did not anticipate that Richards in Harvard would be re- determining the chlorine-silver ratio, and Guye in Geneva and our countrymen, Scott and Gray, would be re- determining nitrogen, and comparing it with silver and chlorine. Silver was one of those few elements so exactly determined that we wrote its atomic weight with six figures, we knew it to a fraction of its ten-thousandth part ! But the new determinations made it necessary either to alter silver or chlorine : hence the sudden importance of an independent determination of chlorine. Dr. Edgar has repeated our experiments in a different manner, and W. A. Noyes in America has made a fresh determination. Guye has also redetermined the density of hydrogen lO Dixon, Inaugural Address. ^ chloride. I think the mean result will be close to our measurement, and that silver will come down in the world and suffer a depreciation of half a per cent. In conclusion I should like to make a few remarks on some matters more directly concerning our Society and its proceedings. Our membership is not so large as it once was, and I have heard more than once in the last ten years dismal forebodings of imminent decay. We may have been too conservative towards new ideas, we may have been too slow to meet the changing conditions of the city's life, we may have leaned too much to philo- sophy and too little to literature; but I am convinced that as a scientific society there is nothing vitally wrong with us. Numbers count ; we cannot carry on our usefulness unless new recruits are ready to join us, and every member should make it a matter of personal pride to introduce friends to our meetings. But numbers are not the first consideration ; we must maintain and if possible increase the interest of our proceedings. I think we should have more papers down on our agenda, though I am not anxious to increase our printer's bill. We need not desire to be the sole channel of publication of communications made to us. Indeed I would ask our scientific workers to bring their discoveries before us as evidence of good-will, but, as editors say, 7iot necessarily for publication. I would specially plead for the introduction, not of the corrected article, but of the rough proof; for the informal discussion of experimental ways and means ; for science in the making. It is at this stage that new ideas, even crude ideas, falling on prepared ground, may be so fruit- ful. We need not be frightened of giving our valuable ideas away : it will be give and take, and besides, ideas are only valuable to those prepared to work them out. MancJicstcr Memoirs, Vol. Hi. (1907). ii It may be objected that more papers on the notice will crowd out or curtail the " short communication " on matters of scientific interest. I think I should not greatly regret if the short communications were crowded — not out, but, say, into a quarter of an hour. I would not urge the abolition of the ' short communication ' — a result which would follow if the proposal were carried that the short-communicant had to give a day's notice to the secretaries. But when vve see members, who have come to hear a particular paper announced on the summons, leaving the room during a long discussion on subjects adventitiously introduced as "short communications," then I think those members have a right to complain that they have been defrauded owing to our inability to perceive that one essential thing about the short com- munication should be its shortness. If I am right in this diagnosis, I shall look to the Society to support the chair in any restrictive measure that may be necessary Those who have been connected with this Society for many years cannot help noticing the gradual change which has come over our personnel. One of our oldest and most devoted members, the late Dr. Schunck, in his farewell letter to the Society, deplored the increase of the professional element and the disappearance of the amateur. I would respectfully join in that regret. I suppose, as the sciences become more specialised, and as measurements become more refined and the instruments needed more costly, the amateur may feel that he cannot keep pace with those who devote their lives professionally to such studies in institutions equipped at the public expense or at that of the pious founder. There is some reason for this feeling ; but I think there is none for another feeling which I believe exists — that professional men of science are jealous of the amateur, and by a 12 Dixon, Iiuxugural Address. conspiracy of silence or contempt seek to obscure his merits and so maintain their own prestige. It is, of course, difficult for an amateur, unless he be a man of wealth and leisure, to improve on the measurements of our fundamental units. My experience, for instance, would not lead me to suggest to a business man anxious for some chemical recreation that he might with advantage re-determine the atomic weight of chlorine. But, on the other hand, no one can carry through a chemical research without meeting numerous problems in the shape of unexpected obstacles, most of which he has to ' side- track ' if he wishes to make progress. And it is surprising what a little way one has to travel before bumping up against the unknown — or the forgotten. If anyone were to ask me the simple question, " Do hydrogen and oxygen combine slowly in the light ? " I should have to say, "I don't know : the evidence is contradictory." Indeed, our ignorance is so vast that there are chemists who do not hesitate to affirm that in all probability nothing combines directly with anything. The study of the conditions under which some simple chemical change occurs would not, I believe, involve great expenditure of time or money ; it would require patience, skill, and enthusiasm, it would require an open mind. Is not the amateur possessed of this armoury ? I have spoken only of the experimental sciences : in astronomy, natural history, geology, does not the amateur hold his own ? Again, does not the amateur bring to our discussions a freshness of ideas which more than compensates for any possible defects of critical judgment? Criticism is cheap — ideas are precious. Ideas are given to the }'oung — judgment is left to the old. And the amateur is always young ! At an age when the professional has given up the game and become an umpire the amateur is still scoring! Manchester Memoirs, Vol. Hi. ( 1 907). 1 3 There seems to me no reason in the nature of things why a professional in one science should not be a success- ful amateur in another — at all events be interested in its aims and development. And probably no more stimulating ideas are struck out than at the personal contact, if I may use the phrase, of two minds trained in different sciences. I know that I am very grateful for ideas received in this meeting-room, and I feel sure that many of our members feel similar gratitude. I would then plead for the cultivation of the amateur. I have tried to show how important he is to our Society : it must be our business to attract and then to interest him. And there is another connected danger which I have heard threatens us. The Society is being swallowed up by the University. As the older Universities sent out " extensions " where the concentrated culture of higher intelligences was diluted down to the density of common comprehensions, so the Manchester University is seeking to establish a " centre " here where similar experiments may be carried ^out ! Speaking as a member of that University I would only ask "Why should we?" We surely have enough lecturing to satisfy our professorial zeal : we are not ambitious to restart evening classes — unpaid. I think I speak for all my colleagues when I say that we come here because this Society knows no distinctions among its members, who meet on a perfectly equal footing whether professors or manufacturers, professional men or students ; because criticism is informal and open to all ; because it is advantageous that we should have mutual interchange of experience and ideas — especially between men of the laboratory and men of the works ; and because it is our pride to maintain as best we may the tradition of this spot — hallowed by the fame of those achievements that know no wane. MancJiestcr Memoirs, Vol. Hi. (1907), No. 1. I. "On the Atomic Weight of Radium." By Henry Wilde, D.Sc, D.C.L., F.R.S. ( Received and read October 2gth, igo'j.) In my paper read before the Society last year\ it was shown from the relations of the specific gravities of the alkaline-earth metals to their atomic weights, and also from the similar relations of the series of alkaline metals, that radium would have a proximate specific gravity of 5, and an atomic weight of 184, notwithstanding the assertions that have been made that the new element would be a heavy metal comparable with thorium (sp. g. 1 1) and uranium (sp. g. 18), and that its atomic | weight ranged between 225 and 258. It was also shown that the atomic weights of the two series Hn and H2n of my tables, are definite multiple differences and not intei'- mediate mivibers. In the several accounts which have been given of the atomic weight of radium, it is stated that the experi- mental determinations were made with radium chloride. Now it is well known to chemists that the series of alkaline metals and alkaline-earth metals, magnesium, calcium, strontium, and barium unite with chlorine in one proportion only. An important gain to chemical science which the multiple differences of the atomic weights have led up ^ Manchester Me/noirsy vol. 51, No. 2, 1906. November 2isf, igoy. 2 Wilde, On the Atomic Weight of Radium. to, is the quantitative determination of the combining proportions of new elements in anticipation of the experi- mental results. Hn H = I Diff. - 6 0.0.7 Li = 7 0-59+ 7* -16 I X 23 . o=Na = 23 0-98 -16 2X 23 — 7 = Ka = 39 0-86 39 3 X 23 — 7 = Cu = 62 8-9 63-3 4x23 — 7 = Rb = 85 1-52 85 5X23-7-Ag =108 io'6 108 6x23 — 7 = Cs =131 1-88 1^2 7x23-7= — =154 I2-2t 8X23-7= — =177 9X23-7 = Hg=2oo n'6 200 23 23 H2n He = 2 Difif. - 6 o . o . 8 = G1 = 8 1-64? 9'2 -16 I X 24 — o = Mg= 24 1 74 24 2X 24 — 8 = Ca = 40 1-58 40 16 -24 3 X 24 — 8 = Zn = 64 7-2 65 -24 4X24-8 = Sr = 88 2-54 87-5 5 X 24 — 8 = Cd =112 8 '69 112 6x24-8 = Ba =136 375 137 7x24 — 8= — =160 10-13::: 8x24-8 = Ra =184 5-o: 9X24-8 = Pb =208 1 1 '44 207 -24 24 -24 24 24 * Accepted Atomic Weights. t Specific Gravities. j Estimated. MancJicstcr ]\Iei)ioiys, Vol. Hi. (1907), No. \. 3 Taking the instance of radium chloride, I have estimated its combining weight after the classical method of Marignac^ and Dumas'' in their experimental deter- mination of the atomic weight of barium as follows : — 1. One part of silver corresponds to viy^ parts of radium chloride, or -. 1-176 2. The atomic weight of silver being 108, we have radium chloride = v\'j6 x 108 = 127 minus CI (35) = 92 the combining weight of radium with chlorine. 3. Now 2x92=184 is the bivalent atomic weight of radium with bivalent oxygen in the positive and negative series H2n, as shown in my general Table, with a possible increase of one unit in the experimental determination, as in the instance of barium (136 — 137). I have previously shown that the positive series of elements H2n closes with lead (208), and that if any higher member of the series of alkaline-earth metals exist, it would have an atomic weight of 232, and an approximate specific gravity of ']:' Assuming this hypothetical member to be radium, the combining equivalent of its chloride with silver (CI 35 and Ag 108) would be i"399 in accordance with the determinations arrived at with the other members of the same series, and not r37i as determined experi- mentally^for the intermediate atomic weight 226, recently assigned to radium.* 1 Bibl. Univ. Archives, 1858, p. 81. ^ Ann. Ckiin. Fhys., vol. 55, p. 139, 1859. ' Manchester Memoirs, vol. 51, No. 2, 1906. ^ Coinptcs rendiis, vol. 145, p. 422, 1907. Manchester Memoirs, Vol. Hi. (1907), No. % IL New Reactions for the Characterisation of Mercerised Cotton, By Julius Hubner, M.ScTech., F.I.C. (Read and received November 26th, igoy.) Although thoroughly mercerised cotton fibres exhibit very distinct microscopic characteristics (Hubner and Pope, Jourjial Soc. Chem. Ind., Vol. XXIII., p. 404), on examining fibres taken from mercerised fabrics it will be found exceedingly difficult, in many instances, to say with certainty whether the goods have been mercerised or not. This may be due to incomplete penetration of the fibre by the soda solution, to the application of certain finish- ing operations after mercerising, and to other causes. So far no reliable chemical reaction for the characteri- sation of mercerised cotton is known. The author has found on immersing mercerised and ordinary cotton in a solution of iodine in saturated potassium iodide solution for a few seconds, and after- wards washing with water, that the colour of the mer- cerised cotton quickly changes to a blueish-black whilst the ordinary cotton becomes lighter in colour and changes to a brownish-chocolate shade. After further washing the ordinary cotton becomes white whilst the mercerised material remains a blueish-black colour, which fades very slowly on prolonged washing. The reaction proceeds still more distinctly and more slowly if, in place of water, a 2 per cent solution of potassium iodide in water is used for washing the cotton after immersion in the reagent. It will then be noticed that after 5 or 6 washings the December 18 th, 1907 ^ 2 HUBNER, Characterisation of Mercerised Cotton. mercerised cotton is of a brownish-black shade whilst the ordinary cotton appears practically white. If now water is added the colour of the mercerised cotton changes immediately into a blueish-black the ordinary cotton remaining white. It is well known that cotton treated with caustic soda solution exhibits increased affinity for the substantive cotton colours and that a considerable contraction takes place during this treatment. Hiibner and Pope (Joe cit.) have shown that both the maximum absorption of colour, and the highest shrinkage of the fibres result from mer- cerising the cotton with caustic soda solution of from 50 to 60° Tw. They have also pointed out that the ratio of colour absorption and of shrinkage is not directly com- parable with the increase of the strength of the caustic soda solution. On applying the reagent described above to cotton mercerised with caustic soda of different strengths, it has been found that a distinct gradation of colour, directly comparable with Hiibner and Pope's results, is produced. On exposing the blue-coloured cotton, after washing, to the air, it will be noticed that on drying the colour fades gradually, and the more slowly the stronger the caustic soda which has been used in the mercerising of the material. If the cotton, after immersion in the reagent, is either not washed at all, or washed with potassium iodide solution, the brown colour of the ordinary and of the weakly mercerised cottons is seen to fade rapidly and very completely on drying, whilst the more strongly mercerised cottons retain the iodine for a very long time. Some of the samples have not faded after an exposure of six weeks. The action of salts other than potassium iodide is at present under observation. Manchester Memoirs^ Vol. Iti. i^igoj), No. ^. 3 The author has ascertained that cotton mercerised either with or without tension possesses the property of absorbing iodine from solution in potassium iodide and water much more freely than does ordinary cotton. Cotton mercerised under tension absorbs less iodine than that mercerised without tension. A parallel between the rate of absorption of colouring matters and of iodine by mercerised cotton has, therefore, been established. If ordinary and mercerised cotton is immersed in 20CC. of water to which two drops of a solution of iodine in potassium iodide, corresponding to about o'OOogy^S gram. of iodine, have been added it will be noticed that both samples are coloured very faintly yellowish. The author has found that, if, in the place of using water, aqueous solutions of zinc chloride are employed, the minute quantity of iodine present exhibits quite a remarkable action on the cotton fibres. The strength of coloration of the cotton increases to a certain point with the increase in the strength of the zinc chloride solution ; the shade of the colour alters, and the difference in the strength of coloration between the mercerised and the ordinary cotton increases also with the strength of the zinc chloride solution until loocc. of solution contains gyi) grams of zinc chloride. At this concentration the ordinary cotton remains practically white whilst the mercerised cotton appears a dark navy-blue colour. Cottons which have been mercerised with different strengths of caustic soda solutions show with this reagent also a gradation in colour by means of which the degree of mercerisation of a given sample may be ascertained. The action of both reagents described above, on cotton treated with mercerising agents other than caustic soda, has also been investigated. The action of sulphuric 4 HUBNER, Characterisation of Mercerised Cotton. acid, phosphoric acid, etc., in place of zinc chloride in the last named reagent has also been studied. Various inorganic salts and organic compounds, in conjunction with iodine, also give typical reactions on cotton ; the author is therefore extending his investigation to these. It should be pointed out that these reagents may prove of value in the distinction of other textile and paper-making fibres, the various artificial silks, etc. The author hopes shortly to lay the results of these investigations before the Society. Manchester Memoirs, Vol. Hi. (1908), No. 3. III. "The Cone of Bothrodendron viundum (Will.)." By D. M. S. Watson, B.Sc, Research Student in the Geological Department, the Victoria Universicy of Manchester. {Received and read, November 12th, jgoy.) In 1880, Williamson described a small hermaphrodite lycopodiaceous cone from a longitudinal section of a specimen obtained from one of the coal balls of the Halifax Hard Bed. He had previously described in detail the large and very characteristic macrospores and isolated microsporangia. In 1893 he figured a portion of the cone not shewing the axis. Solms Laubach ('91) briefly refers to this description of Williamson's, and states in addition that " the structure of the axis is essentially that of the type oi Lepidodendron Harcourtii" (p. 237). This description probably means nothing more than that the axis is Lepidodendroid and has a pith. I believe that Williamson was unacquainted with a trans- verse section of the axis, so that this description of Solms Laubach's may be founded on other sections, possibly those in the Cash collection. These are, so far as I know, the only references to this type of cone ; probably the rarity of whole cones and their usual bad preservation have discouraged investigators. Only five individual complete cones are known to me, but isolated sporangia and spores are very common. January yth, igoS. 2 Watson, TJie Co?te of Bothrodendron inunduni. Microsporophylls have been erroneously identified as Aliadesniia. I am now able to give a fairly complete account of the anatomy and morphology of this tj^pe of cone, and refer it to Bothrodendron iniinduni, the Lepidodendron munduni of Williamson. The material investigated consists of the sections Q454, Q458, Q460, of the Cash collection of the Man- chester Museum, which form a series and are derived Text-fig. I. Diagrammatic median longitudinal section of a cone of B. nnindtun x about 12. /f"=:ligule. 2'/^ = vascular bundle of sporophyll. J-/ = stele of axis. (7= the characteristic groove. T. T- = transfusion tissue. from the Halifax Hard Bed, A 188 of my own collection derived from the mountain 4 ft. coal at South Grain, Manchester Memoirs, Vol. Hi. (1908), No. JJ. 3 Dulesgate, and A204 (my collection) from a coal seam in the second grit at Laneshaw Bridge, collected by Mr. P. Whalley. These sections are all transverse sections of whole cones, there being two in section A 188. No really good longitudinal section of a whole cone exists, that figured by Williamson being badly preserved. Sections R406 and O461 in the Manchester Museum are figured in this paper, and many other sections shewing isolated sporophylls have been used. Description of Cone. General MorpJiology. Except for the presence of a large and very con- spicuous ligule, the cone much resembles that of Lyco- podiuni in general structure (see Text-fig. i). It consists of an axis bearing short sporophylls composed of a small horizontal limb and a lamina on the surface of the cone. On the upper surface of the horizontal portion, and about half-way between the axis of the cone and the lamina, a single sporangium is attached. Between the attachment of the sporangium and the lamina is a large ligule set in a deep ligular pit. Each sporophyll receives a single vascular bundle from the axis. Size of the Cone. In a compressed state, and with the appendages much disarranged, three transverse sections of the cone measure 10, 5, and 2 millimetres in greatest diameter. These differences are correlated with corresponding dif- ferences in the diameter of the axis which measures in the first two cases 3 and 2 millimetres in diameter respectively. 4 Watson, The Cone of Bothrodendron mundum. Taken in the light of the great tapering shewn in WilHamson's longitudinal section, these figures suggest that the cone tapers rapidly. It was probably about 8 millimetres in diameter at its widest place when uncrushed, and tapered to 3 or 4 millimetres at the top. There is no good evidence as to its extreme length, but Williamson's longitudinal section, which includes the tip, shews macrospores at its base and microspores in the superior sporangia : it is thus probably a nearly entire specimen, and its length is 10 mm. approx. The cone was thus of very small dimensions when compared with the majority of the Lycopod cones of the Coal Measures. St met II re of the axis. The wood is hollow and surrounds a pith of ordinary soft parenchymatous cells ; this is as a rule badly pre- served and is of no great interest. The wood is of com- paratively large size when compared with that of an ordinary Lepidostrobjis (See Fig. i of Plate). It consists of an inner layer one tracheid wide of large tracheids, this is succeeded by a belt of much smaller tracheids. This belt exhibits a tendency to be split up into distinct groups, each of which encloses a protoxylem. The protoxylem points do not project, but form a quite smooth surface to the wood. The whole wood very closely resembles that of a small twig of Lepidodeiidrou {= BotJirodendroii) inundum, Will. In one cone on section A 188 a small cjuantity of secondary wood has been developed in an irregulur manner ; this is seen in Fig. 2 of Plate. Secondary wood is not yet known in stems of Bothro- Manchester Memoirs, Vol. Hi. (1908), No. 15. 5 dendroi/\ all those so far obtained are, however, quite small, only about 30 mm. in diameter. It is almost certain that the large stems, well known as impressions, had secondary wood. The cortex in all sections known to me is very badly preserved ; it seems to consist mainly of a soft tissue of large parenchymatous cells. It is bounded externally by a narrow belt, 2 or 3 cells thick, composed of squarish cells, with dark, thick walls (See Fig-. 2 of Plate). Appendages. All the appendages, except some of those at the top, and presumably also some at the bottom of the cone, are sporophyils. Each sporophyll is attached directly to the axis, and its horizontal position projects about 6 — 8 mm. in its natural condition. The sporophyll is attached to the cone by a ver)' narrow attachment (See Fig. 3 oi Plate and Text-Jig. i). The very small area of this attachment accounts for the rarity of whole cones and the great abundance of detached sporophyils. The horizontal portion of the sporophyll soon expands considerably. There are really two tangential ridges across the under surface of sporophyll separated by a deep groove ; the outermost of these is very large and receives a loop of the vascular bundle, it also serves to increase the block of tissue in which the ligular pit is excavated (See Text-Jig. I, and Fig. 3 o{ Plate). The horizontal portion is composed of a small-celled parenchyma coated by a tissue of harder and more rectangular cells ; a definite epidermal layer seems to 6 Watson, TJie Cone of BotJirodendron mundnni. be present. This harder tissue tends to become more abundant towards tlie lamina of the sporophyll. Passing through the sporophyll is a single vascular bundle; this is very small but seems to be collateral and orientated in the normal way. Its course is very simple, emerging from the cortex of the stem it runs directly through the leaf base, looping downwards at the exterior of the horizontal portion, and then passing upwards into the lamina of the sporophyll (See Fig. ^oi Plate). It is surrounded, particularly on the upper side beneath the ligule, with a great deal of tran fusion tissue of the type common in the Lepidodendraceae ; this tissue in the neighbourhood of the ligule nearly cuts out the ordinary parenchyma of the leaf base. The sporangium is attached by quite a narrow neck of tissue to the upper surface of the horizontal limb at about the middle of its length, this neck is roughly circular in transverse section, and is about as high as wide, it forms a pedicel on which the sporangium is seated (See Figs. 3 and 4 o{ Plate). The pedicel contains no vascular tissue. Both micro- and megasporangia are attached in the same way. The pedicel expands into the sporangium with the wall of which its epidermis is continuous. The central tissue of the pedicel forms a little cushion inside the sporangium, and spreads out to form a lining layer to its lower part. The sporangia are higher than they are wide either radially or tangentially. The sporangial wall usually consists of a single layer of cells which are square in section, but irregular equi- diametric polygons in surface view ; they do not shew any trace of the buttresses which occur in Calamitean and sphenophyllaceous fructifications. Manchester Memoirs^ Vol. Hi. (1908), No. *$ 7 The ligule is inserted in a deep depression in the upper surface of the sporophyll, between the upturned lamina and the attachnnent of the sporangium ; this space it entirely fills (See Text-fig. 2 and Figs, i and 3 of Plate'). It is a small organ, with a rounded top, about 0"3 mm. high and 015 mm. broad ; it is composed of small square Text-fig. 2 . Transverse section of a crushed cone zi Bothrodendroii inundum (Will.) A188 D. M. S. Watson's collection from the mountain four foot coal of South Grain Dulesgate. Camera lucida drawing only shading dia- grammatic. X 15 approx. xrii = wood . /«f = middle cortex of axis. 06= outer cortex of axis, displaced. spli = sporophyll. <^= ligule in pit in sporophyll. '//e^. JW = megasporangium. w/r. sm. =microsporangium. parenchymatous cells agreeing exactly with those of the ligule oi ]\Iiadcsinia and the ordinary Lepidodendraceae. The ligule always appears light-coloured in the sections which I have examined. The lamina, which is directed vertically, has a distinct groove on its inner surface which receives the ligule ; this gives an exceedingly characteristic form to transverse sections of the lamina in 8 Watson, TJic Cone of BotJirodendron mundiivi. its lower part (See Fig. 2 of Plate). The lamina continues at least to the height of the top of the sporangium, but I could form no satisfactory idea of its structure in this part from existing sections. Spores. Each cone carries both micro- and megaspores, and it seems most likely that the microspores were in the upper- most sporangia, the megaspores below, as is the case in Williamson's longitudinal section. In this connection it should be mentioned that the microsporangia are usually smaller than the megasporangia. The microspores have the form of quarter spheres and are about '027 mm. in diameter. They are often found associated in tetrads, and except for the ridges produced by this association are without ornament. The megaspores were several times described by Williamson (Will. '78). They are of roughly spheroidal form, and are provided with a projection which interlocks with those of the other spores of the tetrad. Encircling the equator of the spore, assuming the projection to be the pole, is a belt of ramified hairs about 0-15 mm. long. These are exceedingly characteristic, and render the identification of the megaspores easy. No more than four megaspores have been found in any sporangium, and it is almost certain that only one tetrad is normally developed in each sporangium (See Fig. 4 of Plate and Text-fig. 2). For further illustrations of the megaspores see Williamson '78, pi. 23, figs. 58, 59, 60, 64, 66, and "8o,pl. 15, fig- 9- Manchester Memoirs, Vol. Hi. (1908), No. 3. 9 Discussion of the Relationship of the Cone TO Bothrodcudron AND OTHER LVCOPODS. The genus Bothrodcndron was founded by Lindley and Hutton in their" Fossil Flora " (L. and H. '33). They did not define it satisfactorily, and it was regarded as a condition of preservation of various other genera of Lepidodendraceae by most palaeobotanists, until Zeiller ('86) shewed that well preserved specimens existed having definite leaf scars, shewing the prints of the vascular bundle and the two parichnos strands. The genus belongs to the Lepidodendracese, and may be roughly described as being a Lepidodcndrou in which the projection of the leaf basis is nil. Nalhorst has shewn that Cychstignia Kiltorccnsc from the upper old red sandstone is really a Bothrodcudron, the genus also occurs in the lower carboniferous rocks of Scotland, and is hence one of great antiquit)^ It has recently been shewn by Mr. Lomax that Williamson's Lepidodcndrou uuDiduui is a BotJirodcndrou, but the surface of the stem on which the identification is founded does not, in my opinion, warrant specific deter- mination. The only fructification yet referred to Bothro- dendrou is a cone described by Kidston ('89), which was attached to a twig of Bothrodcudron niinutifoliinn Boulay. Owing to the kindness of Mr. Kidston, I have been able to examine in Manchester three examples of this cone, one of which is still attached to an undoubted Bothro- dcudron twig. These specimens are derived from the Middle Coal Measures of Barnsley, Yorkshire. I was unable to clearly make out the structure of these impressions, but believe that it was similar to the cone described above, in the fact that the horizontal limb of the sporophyll is short compared to the diameter of lO Watson, TJie Cone of Bothrodendron vinndtnn. the axis. The horizontal portion of the spcrophyll seems to be much more normal, and like that o{ Lcpidostrobns in B. ininutifolimn than in B. vnindinn. Finally, the cones of B. iniiuitifoliinn are loncj and cylindrical, differing from the tapering cones of B. viuiidum. From these differences it appears certain that BotJiro- dendroji iiiimdum is not B. ini}uttifolium Boulay. It appears likely that B. nuindinn must therefore belong to B. punctatmu, the only other species known as impres- sions from the English Lower Coal Measures (see note).* To this point I shall return in a paper to be shortly published " On the Ulodendroid scar." The attribution of the cone described above to BotJu'odendr^on niunduvi (Will.) rests on the following data : — 1. The wood of the axis of the cone corresponds exactly with that of a small twig of />. niundum. This correspondence in structure was noticed by Mr. Maslen whilst cataloguing O454 in the Manchester Museum register. 2. The horizontal portion of the sporophyll between the ligule and the axis corresponding to the leaf base of an ordinary Lepidodendroid stem is much shortened radially when compared with Lepidostrohus, a modification homologous to that of the leaf bases of BotJirodciidron. 3. The two foregoing arguments are supported by constant association of the stems oi Bothrodendron uuindiini and the cones or their sporophylls or *It is possible tliat oihei- species of Bothrodendron may occur in the Lower Coal Measures, but B. pitnctaiiun and B. ininutifoliiun are certainly the only common species. Manchester MevioDS, Vol. hi. (1908), No. J5. 1 1 megaspores, as described above ; for example, all the sections, about 20 in number, forming the Williamson series of Lcpidodciidron inimdiim also contain these characteristic megaspores. In nearly all the sections containing Boihrodeudroit inunduvi in the Manchester Museum and my own collections fabout 30 in number) I have been able to find these spores. This series of about 50 sections, shewing the associa- tion of the stems and cones, is derived from 3 horizons in the Millstone Grit and Lower Coal Measures (see Stopes and Watson), and the following localities : — Halifax, Huddersfield, Hough Hill, Shore, Bacup, Cloughfoot, and South-Grain collieries at Dulesgate and Laneshaw Bridge, near Colne. Isolated microsporangiate sporophylls of the Bothro- dendron cone have been confused with those of Miadcsmia. This confusion, I believe, arose in the following way : the majority of the specimens of the peculiar "seeds" of Miadcsmia, first described by Miss Benson in the New Phytologist,\\z.vQ. occurred in a few blocks from Cloughfoot Colliery, Dulesgate. These blocks contain fragments of at least three distinct tx'pes of Lycopodiaceous cones. These cones are the cone described above, the cone of Miadcsmia, and another small cone which I hope to describe shortly. The isolated sporophylls of Miadcsmia and Bothro- dcndrou agree in the following particulars. They are both Lycopodiaceous cones in which the sporophylls are not greatly radially extended as in Lepidosirobus ; they are very small and delicate and nearly of the same size ; they are both provided with a large and very conspicuous lisfule. 12 Watson, Tlie Cone of BotJirodeiidron innnduni. The isolated male sporophylLs may be separated by the following characters* : — - 1. The Bothrodendron sporophylls do not terminate in the characteristic lamina, only one cell thick, of Miadesmia inembranacea, Bertrand. 2. In Bothrodendron there is a great development of transfusion tissue in the sporophyll, particularly round the base of the ligule : in the true JSIiadesniia there is little or none. 3. The vascular bundle in Bothrodendro)i is continued in the lamina up to the level of the top of the sporangium ; in Miadesmia it stops sooner. 4. The tip of the ligule is normally rounded in the sporophylls o{ Bothrodendron. I understand from Miss Benson that in Miadesmia the tip of the ligule is "lamellar." [Letter, August 24th, 1907.] Taken as a whole, the cone of Bothrodendron differs essentially from that of Bliadesmia in the following respects : — In Bothrodendron the megasporangium contains four functional megaspores and is not surrounded by an integu- ment ; in Miadesmia the sporangium contains only one megaspore and is surrounded by a highly specialised integument. The idea occurred to me that Miadesmia and Bothro- dendron might be connected as are Lepidoearpon and Lepidostrohus, but the great differences in stem structure * I have been unable to compare the sporophylls of Botlirodendron wilh those of Miadesmia in much detail owing to the fact that my knowledge of Miadesmia is derived entirely from the poor preparations in the Manchester collections. I look forward to the forthcoming monograph, by Miss Benson, on Miadesmia to reveal many oth), A o. *^. 15 BIBLIOGRAPHY. Benson, M. :02. " A New Lycopodiaceous seed-like Organ." New F/iylologist, vol. i, p. 8g, 1902. Berridge. :05- "On two new Specimens of Spencerites insignis. Ami. Bo/., vol. ig, pp. 273-279, pis. 11-12. KiDSTON, R. '89. " Additional Notes on some British Car- boniferous Lycopods," An7i. Mag. Nat. Hist., [6], vol. 4, p. 60, pi. 4. Scott, D. H. :o6. " On the present position of Palaeozoic Botany" in "Progressus rei Botannicae" Leipsic, 1906. Solms-Laubach, H. Graf-zu. '91, "Fossil Botany." Oxford, 1891. Stopes, M. C. and Watson, D. M, S. "On the present Dis- tribution and mode of origin of the Calcareous Structures in Coal Seams, known as Coal Balls." Phil. Trans., not yet published. Williamson, W. C. '78- " On the Organisation of the Fossil Plants from the Coal Measures." Phil. Trans., vol. 169, part 2, p. 319. '80. Ibid., vol. 171, part 2, p. 493. 1 6 Watson, The Cone of BotJirodendron vnindiim. DESCRIPTION OF PLATE. Fig. I. Photograph of a transverse section of a cone. x 13 approx. spK =a sporophyll shewing attachment of sporangin. spJi =-x sporophyll cut at the level of the top of the ligule showing the characteristic shape and groove for the ligule. 4' = the ligule of sporophyll spK' . Hard bed, Halifax. Q460. Cash Collection, Manchester Museum. Fig. 2. Photograph of a transverse section of the wood of an axis of a Bothrodendron cone. x 41, px = a protoxylem. .r' = arc of secondary wood. Note the perfect correspondence with the wood of a branch of Z. mimdiim (Will.). A 1 88. D. Watson collection. Mountain four foot mine, South Grain, Dulesgate. Fig. 3. Radial section of an isolated microsporophyll [? abortive] of the Bothrodendron cone. x 45. vb = vascular bundle. 4'-= ligule. TT— Transfusion tracheids. ^r= Characteristic groove, compare Fig. 4. fl/= Attachment. w^' = Isolated megaspore. From the Halifax hard bed. R406. Hick Collection, Manchester Museum. Fig. 4. Oblique section of a macrosporophyll of the Bothro- dendron cone missing the ligule, but containing two of the characteristic spores. x 45. vb = vascular bundle. TT== transfusion tissue. ^/'=The characteristic groove, compare Fig. 3. From the Halifax hard bed. Q461. Cash Collection, Manchester Museum. Mixnchestcy Memoirs, Vo/. LI/, {yo. *X). Fig. r. Plate. /g spli' sph' Fig. 3. Fi.;. Fr vb TT MaiicJiestcr Memoirs, Vol. Hi. (1908), No. A. IV. "On the Ulodendroid Scar." By D. M. S. Watson, B.Sc. Kescarcli Student in the Geological Department of the J Ictoria University of Manchester. ( KeeeiTcd and Read Novc///l>er i3th, igoy. ) Certain stems of the genera Sigillaria, Lcpidodcttdroii and Bothrodctidrou are found to bear two opposite rows of large depressed scars. Such stems are said to be in the Ulodendroid condition, and were formerly included in the " genus " Ulodctidroti. These curious Ulodendroid scars were known ver}' early in the study of Pala;obotany, and many explana- tions of their meaning and mode of formation have been put forward. The explanation which has secured general accept- ance is that they bore sessile cones which were not attached to the whole area of the scar, but onh' to the central or sub-central umbilicus, and which by their pressure, obliterated the leaf bases over the whole area of the scar. The large size of the scars is explained by the supporters of this theory as due to growth subsequent to formation, and to the shedding of the cones. Other views which have been put forward, but which have not secured any wide acceptance, are : — I. That due to Stur, who supposed the scars to have been produced by the pressure of the bases of bulbils. This view is a modification of the ordinary view, and is explained b\- the fact that Stur knew that certain January yi/i, igoS. 2 Watson, On the Ulodcndroid Scar. species which occur in the Ulodendroid condition bear their cones attached to the fine ultimate twigs. It seemed to him very unHkely that a Lycopod should bear cones in two distinct ways, so he was forced to discover some other organ to take the place of a cone, and, remembering the bulbils of Lycopodiuvi sclago, applied the idea to Lcpidodendron. 2. Another idea, due to Carruthers, is that the scars represent the bases of roots which arose adventitiously on the stems and were attached to the whole area of the scar. This view has been combatted by Williamson and Kidston. The theory that I intend to support in this paper is that the scars are those of branches which were attached to the whole area of the scar. In a recent paper (Watson :07) I described the cone of BotJirodcndron iiuindnm Will, and shewed that it did not belong to Ik iiiiuutifoliiiui, Boulay, but probably to B. punctatinn, L. & H. This cone is extremely small, less than a centimetre in diameter, and quite short, and it is very difficult to see how it could have produced the enormous Ulodendroid scars which often occur in B. piinctatuiii. If it be suggested that the Ulodendroid scars grew after formation more difficulties are raised, for, whilst it is certain that Lepido- dendroid stems increased in diameter by secondary growth, it is very unlikely that they would elongate verti- cally after becoming sufficiently adult to bear cones. If these scars did grow appreciably I think that the ten- dency of such growth would be to produce scars broader than high, and I think no examples of such scars are known. This fact alone leads one to suppose that the organs producing the scars must have been attached to the stem until the cessation by death or otherwise of MancJicstcr JMcmoirs, Vol. Hi. (1908), No. 4. 3 secondary growth. If this be true these small Bothro- deiidron cones cannot have produced the great Uloden- droid scars of /A punctatuiii. The largest definite strobilus of a Lepidodendroid tree with which I am acquainted is Lepidostrobiis Broivnii, the internal structure of which is preserved. The diameter of this cone is two inches, and Ulodendroid scars are known about four times this size. The fact that certain species which bear Ulodendroid scars are known to have cones attached to the ultimate branches suggests that the Ulodendroid scars could not have directly borne cones, as it is exceedingly unlikely that a Lycopod would carry its cones in two distinct ways. There is thus a certain amount of evidence that " Ulodcii- droiT could not have had sessile cones attached to its scars. The principal specimen on which I depend for support to the branch theory is contained in the Man- chester Museum. It is represented in Plates I. and //. This specimen is a cast in very fine Coal Measure sandstone of one Ulodendroid scar probably referable, on account of its ovoid form and eccentric umbilicus, to Bothrodendroii pnnctatinn L. & H. The specimen is not localized and not registered, but Professor W. Boyd Dawkins informs me that it is probably from the Middle Coal Measures of Peel Uelph Quarry, near Bolton. It is to be particularly noticed that this scar apparently formed the centre of a concretionary area in the sandstone, and that in parts a certain amount of structure is preserved in iron carbonate. One of the remarkable characters of this specimen is that in the obverse half (see Figs. 3, 4, Plate II.) the umbilicus is represented by a cylindrical hole 18 mm. deep and 8 mm. in diameter. This hole is surrounded by an upstanding ring of iron 4 Watson, On tJic U lode nd raid Scar. pyrites and probabl}' iron carbonate, which must represent some portion of the original plant, and which is not a cast. In the reverse (see Fi[(^. 2, Plate /.), the continuation of this ring is seen, and it is seen to give origin to numerous small strands which pass outwards. In one place on the lower half of the scar these are intercepted by a plane of fracture, and have the arrangement of dots characteristic of ordinary Ulodendroid scars in this region. These strands and the tissue in which they run are imperfectly petrified. I think that the appearances seen on this specimen cannot be explained on the orthodox view, but receive a ready explanation by the theory that the scar represents the base of a branch attached to the whole scar. The explanation I wish to propose is as follows : — That a small portion of the base of this branch still remains attached to the scar, and that this patch of tissue was much macerated and decayed before fossilization, all its soft tissues being removed, whilst its vascular system was left almost intact.* I believe that this fragment of the base 01 the branch was then imperfectly petrified. The ring surrounding the depression in the umbilicus is, I believe, the actual primary wood cylinder, and the small strands to which it gives origin are leaf traces which pass outwards to supply leaves attached to the branch. The size of the Ulodendroid scar is 95 mm. by 80 mm. On the branch theory 80 mm., the horizontal diameter, will represent the diameter of the base of the branch. On the assumption that the upstanding ring round the *We know from the evidence of petrified stems that this is how Lepido- dendroid branches did decay. Manchester' McDioirs, Vol. Hi. (1908), No. 4. 5 umbilicus represents the primary wood, the ratios of the diameter of the wood to that of the branch would be I to 8. Measurements of 9 petrified stems of similar dimen- sions belonging to Lepidodcudroii fiiliginosuiii, L. sclagi- noidcs Car. \iuxsciilarc Binney], L. Harcoiirtii and L. Wuiischianniii gave I to 77 as the average ratio of the diameters of wood and stem. I think that these ratios are so close as to lend support to the view I have here adopted. If the appendicular organ was only attached to the umbilicus then it is very difficult to satisfactorily explain the hole. It could I think be only explained by supposing that the cortex of the appendicular organs penetrated into the cortex of the stem ; it is not easy to see how this could happen to the peduncle of a sessile cone. The branch theory has the advantage of explaining easily the markings observed on the ordinary Ulodendroid scars. These markings consist of a central or sub-central point usually represented by a prominence on the specimen. This umbilicus is surrounded by imprints or projec- tions covering the surface of the scar ; these projections are arranged so as to form a series of helices starting from the umbilicus and passing outward to the edge of the scar, forming, as Hugh Miller said, an engine- turning pattern. They are, in fact, on at least the lower portion of the scar, arranged exactly as the leaf traces are in a transverse section of a Lepidodendroid stem. They have already been figured by Carruthers, Kidston. and many other palaeobotanists. In circular 6 Watson, On the Ulodcndroid Sccxr. scars with a central umbilicus these dots are usually- continued all round the scar, but in oval scars with an eccentric umbilicus they only cover the lower portion, the upper being covered by longitudinal markings radially arranged, which, however, gradually shorten at the sides of the scar and shade off into the dots of the lower part. I do not see how this arrangement, which is the normal one, can be satisfactorily accounted for on the theory that the dots represent crushed leaf-bases, which is that adopted by the upholders of the orthodox cone view. If they do represent crushed leaf-bases then these must vary very greatly in size and shape (wer the area of the scar, which however is supposed to have been only an ordinary piece of the stem surface. On the branch theory the dots merely represent the cut ends of vascular bundles supplying leaves formerly attached to the branch, and the difficulty of their varj'ing distances apart does not arise ; on this theory also the longitudinal markings on the upper part of the scar are .accounted for as being obliquely and sometimes longi- tudinally cut leaf-traces. It must be pointed out that in the specimen described above, which shows the leaf-traces and their origin from the wood, these explanations seem to work perfectly. The Text-figure will, I hope, make the meaning of this explanation more clear ; it should be compared with a somewhat similar figure given by Carruthers. The branch theory also explains the fact that Ulodcn- droid scars are often provided with a raised rim at the edge. It simply represents, I take it, a scrap of the outer cortex of the branch left connected to the parent stem. An additional argument in favour of the branch view, is that we know that some Lepidodendra, of which the structure is known, did bear their branches in two MancJiestey Jllcinoirs, PW. Hi. (iyo8), No. 4. Tr. St. Uiagrainmatic sectiun through ihe base uf a branch to iUustrate the Branch theory of the Ulodendroid Scar. oc. I. = Outer cortex [periderm] of main stem. DC. 2. — ,, ,, of Ijranch. Tr. St. = wood cylinder of main .stem. Br. St. = ,, of branch. It = leaf-trace. L.S. = line of separation of branch to leave in Ulodendroid scar. Wood shaded diagonally. Periderm shaded longitudinally. 8 Watson, Oh the Ulodouli-oid Scai . opposite rows, for example, Lcpidodciidron sclaginoidcs Car., or vascnlai-c Binney (see Weiss and Lomax, :05), and Lcpidodciidron Hickii Watson (see Watson, :07). Against the branch theory, the evidence of three specimens will be used, they are — 1. The specimen described and figured by Professor D'Arcy Thompson ('8o) as shewing a cone in connection with a Ulodendroid scar. 2. The specimen referred to by Professor D'Arcy Thompson and figured by Mr. Kidston in '85. 3. The specimen figured by Mr. Kidston ('85) which shews a Ulodendroid scar apparently covered by fairly well preserved leaf bases. I shall endeavour to shew that these specimens can be explained on the branch theor}-. I. The specimen figured natural size by Thompson shews an organ apparently attached to the centre of an ill-defined Ulodendroid scar. A series of Ulodendroid scars is continued below the organ. Judging from the figure, the surface of the important Ulodendroid scar is nearly flat, and the organ lying in the same plane is apparently attached only to the umbilicus. The basal end of the organ increases rapidly in diameter, so that at a distance of about 5 cm. from the attachment, the organ is nearly 5 cm. in diameter. If the Ulodendroid scars are produced by the pressure of the bases of such cones, they must be very deep, in fact, at least 5 cm. deep, as they are about the same thickness as the diameter of organ at that point. From our knowledge of the characters of the cortices of old Lepidodendroid stems, we know that this deep Ulodendroid scar would have to be excavated in a tough and decay-resisting mass of tissue ; how such a mass of tissue could be crushed flat, and the organ, tightly fitting MancJiCster Memoirs^ Vol. Hi. (1908), No. 4. 9 into such a deep hollow, could be bent over laterally without breaking oiT, I do not understand. I think, there- fore, that one of the two following explanations must be true. Either the organ is not really attached, or, it is attached, but the Ulodendroid scar was in life almost flat, and hence could not have been produced by pressure of the deeply conical base of the organ. With regard to the determination of the organ as a cone, I can only say, that judging from the figure given b\' Thompson, it is impossible to decide definitely as to its true nature. 2. The second specimen consists of a single Uloden- droid scar preserved on a sandstone cast, into which fits the base of an appendicular organ. This organ is broken off very short, about v^ cm. still remaining. It shews on its surface some ill-preserved scars, which may be the worn bracts of a cone, or equally well ill- preserved leaf-scars. A comparison of Mr. Kidston's figures of the undeniable leaf-scars on the stem, and the markings on the appendicular organ shows that the differences between them are very slight, in fact, Mr. Kidston admits that they are so. The character presented by this specimen, on which most stress has been laid as shewing that the appendicular organ, whatever its nature, was only attached to the umbilicus, is that, with the exception of the central point, the whole area of the scar is covered with a layer of coal. It seems to me that this specimen can be completely explained on the branch theory, if we suppose that there was a branch shedding mechanism in connection with which a layer of periderm was formed across the base of the branch, cutting across the soft tissues of the middle cortex into the wood ; such a la\'er of periderm would not lo Watson, On the Ulodoidi-oid Scar. decay away, and it is easy to see how the vascular CN'h'nder of the branch might be torn out, leaving- a hole in the centre. U'hen fossilised, this lax^er of periderm would be con- verted into coal, forming a film over the area of the scar, and the hole in the centre would be alone left uncovered. The 3rd specimen, also figured by Mr. Kidston, shews the place where a Ulodendroid scar should be covered with moderately well preserved leaf-bases. These leaf- bases are arranged in the same series as those on the ordinary surface of the stem in the lower part of the scar, but it must be very distinctly noticed that in the upper part they do not at all fit into the ordinary stem series. It should also be noticed that this scar is raised above the general surface of the stem. I explain the appearance shewn on this scar as being due to a small bit of the leaf-scar-bearing cortex of the branch being left attached to the lower part of the edge of the scar, and being folded over and crushed down on to the area of the scar. This explanation it seems to me is adequate to explain the fact that the leaf-scars on the scar surface are in the same series as the stem leaf-bases at the lower part of the scar, but do not fit at the top. Summary. It is pointed out that there is a good deal of evidence tending to discredit the ordinary theory of the method of formation and significance of the Ulodendroid scar, in that it is produced by the pressure of the base of a sessile cone. It is suggested that the Ulodendroid scar merely represents the place of insertion of an ordinary branch, which was probably provided with some sort of branch- shedding mechanism. A specimen is brought forward which is interpreted. l\IancJiester Memoirs, Vol. Hi. (190S), .A^6'. 4. 11 as shewing the wood and leaf-traces of the base of the branch. It is pointed out that certain Lepidodendra (Z. vascii- lare Rinney and L. Hickii Watson) certainly bore branches in two opposite rows. The most important specimens adduced in support of the cone theory are shewn to be explicable on the branch theory. Finall}', I wish to express my thanks to Dr. Ho} le for allowing me to describe the Manchester Museum specimen, and to Professor VV. Boyd Dawkins in whose department the work has been done. BIBLIOGRAPHY. Carruthkrs, W. '70. "On the Nature of the Scars in the stems of Ulode7idroii, Bothrodetidroii, and iMegap/iyiiim., with a synopsis of the species found in Britain." Monthly Microsc. Jour/i., vol. 3, p. 144. KiDSTON, R. '85. " On the relationship of Uhdejidron, Lindley and Hutton, to Lepidodendron, Sternberg ; Bothrodcndron, Lindley and Hutton ; Sigillaria, Brongniart ; and Rhx- tidodendron, Boulay." Ann. Mag. Nat. Hist. [5], vol. 16, pp. 123- 179, and 239-260, pis. 3-7, 1885, Stur. '75*77- ''Culm Flora,'' pp. 262^ 267, 270, and 283. Thompson, D'Arcy, W. '8o. " Notes on Ulodendron and Halonia." Trans. Edinh. Geol. Soc, vol. 3, p. 341, 1880. Watson, D. M. S. '.Oj} "On a confusion of two species of Lepiodendron," etc. Manchester Memoirs., vol. 51, No. 13, 1907. :07-" " On the cone of Bothrodendron mundjunJ'' Matichester Alemoirs, vol. 52, No. 3, 1907. AVeiss, F. E. and Lomax, J. :o5. "The Stem and Branches of Lepidodendron selaginoides." Manchester Memoirs, vol. 49, No. 17, 1905. Williamson, W. C. '72. " On the Organisation of the Fossil Plants of the Coal Measures." Phil Trans., vol. 162, p. 209, pis. 26-2S, 1 87 2. 12 Watson, 0)i the Uhdcndroid Scar. DESCRIPTION OF PLATES. All photographs by the Aiitlior. Fig. I. General view of the reverse of the whole Ulodendroid scar. X about \. Middle Coal Measures, Peel, Delph ? In the Manchester Museum. Note the elliptical form and excentric umbilicus. Fig. 2. The subject of Fig. i seen from below and slightly from the left. Almost natural size. X the partly petrified wood ring which joins on to X in Li' Leaf-trace arising from the wood X. Lt" Leaf-trace further out than IJ' . Manchester Memoirs, Vol. LII. {No. \), Plate I. Fiq. I. I-'k. 2. 14 Watson, On the Ulodendroid Saxr. Fig. 3. The Ulodendroid scar itself viewed normally to the stem. X about A. The opposite half to Fig. i. X = the upstanding ring round the hole in the Umbilicus. Lt - Leaf-trace cut transversely shewing with the other traces the Engine-turning pattern. Fig. 4. The subject of Fig. 3 viewed from above and in front, looking directly down the hole, x about |. H = the hole in the Umbilicus, i8mm. deep, sur- rounded by the upstanding ring representing the wood. (Owing to the lighting employed this hole does not appear so deep as it really is). Manchester Mevioirs, Vol. LI I. {No. 4). P/ale I J - X -^Lt ^''iS- 3. L- )C A?- 4. MancJiester Memoirs, Vol. Hi. (1908), No. 5. V. On a new Phytophagous Mite, Lohmannia insigms, Berl. var. dissimiUs n. var., with notes on other species of economic importance. By C. Gordon Hewitt, M.Sc, Lecturer in Economic Zoology ^ University of Manchester. Received and Read December loth, igoy. The species of mites to which these notes refer have been sent to me for identification during the past two years, and as one of them is a new and interesting variety, and the other two species are of some economic importance, these notes have been written. LoJiinannia insignis, Berlese var. dissii/iilis, n. var. The Oribatidac, to which family of the Acarina this mite belongs are phytophagous, and in the adult stage usually possess tracheae. Tlie anterior portion of the body, the cephalothorax, is usually divided from the abdomen by a transverse constriction. On the dorsal side of the cephalothorax a pair of pseudostigmatic organs are borne by a pair of stigmatic-like tubes, the pseudo- stigmata. The species, Lohniajinia insignis, of which this is a new and distinct variety, was recorded by Berlese in 1904 ; the specimens were sent to him by Colonel F. N. Halbert from Ireland. I obtained my specimens from some tulip bulbs which Professor S. J. Hickson brought to me from his garden in Withington early in May of 1907. The tulips pro- duced leaves, and gradually died off without flowering. On examining the bulbs I discovered considerable numbers of the mite beneath the scaly epidermis of the faniiary lyth, i(jo8. 2 Hewitt, On a new PJiytophagons Mite. scale-leaves. A number of the bulbs were kept, and when they were examined six months later not a single specimen of this species could be found, but I found large numbers of Rliizoglyphus ccJiinopus to which I shall refer later. Mr. Michael, to whom I submitted some specimens, pointed out to me its similarity to L. insignis, Berl., remarking that the length of the hairs differed. Professor Berlese very kindly sent me his type specimen of that species to examine and compare. As a result of this comparison I found a number of distinct and striking differences between L. insignis and my specimens, but although these differences might be considered of specific value by those acarologists who, unfortunately, make new species upon very small differences, I think it is preferable to regard the mite as a variety of Z. insignis. This variety [PL figs, i & 2) resembles L. insignis in several major characters. It is similar in colour, being a dull brown with darker legs. It is also similar in size, its average length being imm. The abdomen is also very similar in shape. The differences however, are well marked. The cephalothorax is not pointed as in L. insignis, but is more rounded at the rostral extremity ; in this character it is somewhat intermediate between L. insignis and L. cylindrica Berl. The arrangement and number of hairs on the cephalothorax is quite different. In L. insignis var. dissiniilis there are two fairly long median hairs, and a very small pair, slightly more posterior. There is a pair of long inter-stigmatic hairs ; anterior to these there is a pair of shorter hairs. In the anterior lateral region of the notogaster, there are three pairs of hairs which are absent in L. insignis. This variety has also a few other additional abdominal hairs, but there are fewer hairs on the legs. These differences are constant, so that they do not constitute a sexual difference. On Manchester Memoirs^ Vol. In. {\god>), No. ^. 3 account of the presence of the median cephalothoracic hairs which is a very exceptional character, I have called this variety LoJunajinia insignis var. dissiiinlis. Glycypliagus spinipcs Koch. This species of mite and RJiizoglypJms eclmiopus are members of the family Tyroglyphidae, of which the typical and best known example is TyroglypJins siro, the cheese mite. The group is one of considerable economic importance on account of the damage for which many of the members are responsible and the annoyance caused by others on account of their enormous numbers. GlycypJiagus spinipcs {Text-fig. A) is similar in its habits to its near relative G. doincsticiis de Geer, with which it is often confused, especially as it has at first sight a structural resemblance to that species. On careful examination several important differences will be found. The body of G. spinipes is constricted anterior to the third pair of legs and is narrower behind this region, in G. doinesticiis there is no such constriction. The slender tarsi of G. spinipes are longer than those of G. doniesticus and are covered with fine short hairs, hence the specific name of this mite. G. spinipes also bears a small bract- like scale on the third joint of the third leg (see Fig.) This species is pearly white in colour ; the males measure about •5 mm. and the females 7mm. in length. The body is covered with a large number of long and finely pectinated hairs ; the number and arrangement of these can be seen from the figure, the longest hairs are those on the posterior half of the body. These mites are able to run with considerable rapidity, and when they occur they swarm in such substances as dried animal and vegetable matter. I have received specimens in the 4 Hewitt, On a netv PJiytophagoiis Mite. horse-hair stuffing of chairs, where they appeared to be feeding on the greasy substances in the hair. Oudemans (1897) also records its occurrence in the same material in Holland. Text-fig. A. Glycyphagus spinipes. ^ . x 70. Dorsal aspect. The worst case of infection of this species which I have known was in a house in the neighbourhood of Manchester, in 1905-6. The house had been recently built, and the furniture was new. Shortly after the house had been occupied this mite was found in practically all Manchester Me7noirs, Vol. Hi. (1908), No. 5. 5 the rooms. By the use of considerable quantities of naphthahne, and also ammonia, carbolic acid, and turpen- tine, etc., it was eradicated from all the rooms except one, to exterminate it from which all efforts failed. Each morning the furniture of this room would be covered over with a fine, white dust, which consisted of thousands of mites ; the room could not be used on account of the presence of the mite. It was at this juncture that I was asked for advice as to the pest and its eradication. Discovering that it was G. spinipes, I came to the conclu- sion that it was in the stuffing of the furniture of the room, which probably had served as the original source of infection and distribution. I recommended the owners to send the furniture and carpet away to be stoved, after which the room was to be made as airtight as possible, and fumigated several times with nicotine vapour at intervals of a week or ten days ; after this procedure, the paper was to be stripped from the walls, and the walls and floor thoroughly washed with a fairly strong solution of carbolic acid, and afterwards it was to be repainted and papered. These recommendations were carried out early in 1906. In August, 1907, I was informed on inquiry that the mite had not returned, and that the house was entirely free from the pest. To be certain of eradicating the pest, the owners had disposed of the suite of furniture after it had been stoved, as I had suggested that it was the original source of infection. This case and others which have occurred point to the necessity of having the materials, such as the stufifing of chairs and mattresses, which are used in the prepara- tion of the adjuncts of a comfortable age, properly treated so as to render them unattractive by the absence of food matter to such annoying pests as these species of Tyro- glyphidae, which are not injurious to man, but become a 6 Hewitt, On a neiv Phytophagous Mite. pest on account of their enormous numbers and rapid multiplication. RliizoglvpJins cchiuopits, Fumouze & Robin (1868). This bulbicolous mite has been described under a number of different names, as will be seen from the bibliography in Michael's description of the species (1903) : Murray in his handbook (1877) describes it under three names. This multiplicity of specific names is due, I think, to the large amount of variation which is found in different specimens, especially males, and also their different food habits. Banks (1906) in his recent memoir on the American Tyroglyphidae calls this species R. JiyacyutJii Boisduval. As Michael has already pointed out (/.^.), this name cannot be satisfactorily followed, as the habitat is the only clue which we have to its being this species, on this account I think it is preferable to retain the specific name cchinopiis of Fumouze & Robin. Banks also retains Riley's species /v. //{/'//(ruT/vr^ distinct, although Michael considers the species to be A'. ecJiinopus. I do not think in view of the variations which occur in this and other species of mites, that Banks is quite justified in his multiplication of the species. The average length of mature specimens is a little over "Smm., the males being slightly smaller than the females. They are yellowish-white in colour, the legs being reddish-brown. The anterior region of the body, the cephalothorax, is conical and is divided from the abdomen by a distinct groove. The sides of the abdomen bear a number of setae, the arrangement and number of these in the male is shown in the figure. The female has a larger number of setae, an additional pair is situated in front of the antero-lateral abdominal setae, and several Manchester Memoirs, Vol. Hi. (1908), N'o. 5. 7 additional pairs are found at the posterior end of the abdomen. These setas, in the females especially, are subject to considerable variations in size. The specific Text -fig. B. KliizoglypJuj.s echiiiopiis. $ . x 125. Dorsal aspect. a. Terminal ioint (tarsus) of third left leg. h. Terminal joint of first right leg. name ecJiinopus refers to the nature of the legs of the species which bear a number of spines as shown in Text- 8 Hewitt, On a neiv PJiyiopJiagoiis Mite. fig. B a and b. Michael is doubtful whether the number of spines is constant and Canestrini makes the number different ; I have examined a number of specimens and find that they are fairly, though not absolutely, constant in number and position. The claws are stout and strongly curved. The genital opening is situated between the bases of the posterior pair of legs and the anus is more posterior on the ventral side. This species was found on tulips, together with L. insignis var. dissitnilis. The hyacinth and tulip are the chief food plants of this mite ; bulbs of liliaceous plants appear to be chiefly attacked, and it is popularly known as the "bulb mite." It is also called the '' EucJiaris mite," on account of its apparent preference for the bulbs of that plant, but it is no doubt more frequently found on Encliaris bulbs, on account of their greater value, which results in greater care and examination of the bulbs. Claparede (i86S) found it in hyacinth bulbs, and also on dahlia and potato tubers ; in the one case he named the species R. dujai-dini, and in the other he gave it the name R. robini, not recognising that the male was dimorphic in the character of the third pair of legs, which in some specimens are very stout ; he mistook the thick-legged form of the male for the female. It has been recorded on the roots of the vine. As it is responsible for considerable damage to such plants as hyacinths, tulips, onions, etc., this mite is of economic importance. It is supposed by some authors to follow decay, but I have found it attack- ing fresh bulbs, and Michael finds that it usually prefers these. I have not only found it between the scales, but also beneath the epidermis, where it was attacking the softer tissues. Apart from the damage for which it is directly responsible, it provides entrance for fungal and bacterial organisms, which produce further decay. Manchester Memoirs, Vol. Hi. (1908), No. 5. 9 As in the case of the majority of mites, it is extremely difficult to eradicate when it has estabh'shed itself in the garden, as it lives beneath the surface of the soil. The safest remedy is to burn the infected bulbs and roast the adjacent earth. If the bulbs are considered to be too valuable to burn, they might be carefully treated with paraffin or kerosine several times at intervals of a week or two. Fumigating in a small chamber with nicotine or hydrocyanic gas at intervals, as the gas will not kill them m the ^gg state, would probably destroy the mites. LITERATURE REFERRED TO. 1868, Claparbde, E. " Studien an Acariden." Zeitschr. f. wiss. ZooL, vol 18, p. 445-546, II pis. 1868. FuMouzE, A. and Robin, Ch. -Observations sur una nouvelle espece d'Acariens du genre Tyroglyphe." Journ. Anai. Physiol., vol. 5, p. 287. 1877. Murray, A. "Economic Entomology: Aptera." South Kensington Museum Handbooks, p. 257-259. 1897. OUDEMANS, A. C. "List of Dutch Acari." 7th part "Acaridae" in Tidschr. entom., vol. 40, p. 250-260. 1903. Michael, A. D. -British Tyroglyphidae," vol. 2, p. 84-96. Ray Society. 1904. Berlese, Antonio. "Acari nuovi." Redta, vol. 2, p. 1-32, 2 pis. 10 Hewitt, On a new Phytophagous Mite. EXPLANATION OP PLATE. Lohmannia insignis, Berl. var. dissimilis, n. var. Pig. I. Dorsal aspect, x 75. Pig. 2. Ventral aspect, x 48. Manchester Memoirs, Vol. LII. {No. 5). Plate. Fie. I. Fi.s[. 2. J C.G.H. del. O. V. D. ihoto. MancJiester Memoirs, Vol. Hi. (igo8), No. 6. VI. Some Notes on the Mammals of Lundy. By T. A. Coward, F.Z.S. Received and read, December loth, igoj. The Mammalian fauna of Lundy has not received the same attention as some other branches of its fauna and flora, for instance as its birds, beetles, and land and fresh- water shells. All British mammals have until recently been much neglected, and the number of species found on Lundy is so small that the collector has not been attracted. Incidentally its mammals have been referred to in journals and newspapers, but there is no complete list ; the statements made by J. R. Chanter in his " Lundy Island " (l), published in 1877, are frequently quoted as if they comprised all that could be said on the subject. To correct a few misconceptions and add a little to the knowledge of the Island I offer these notes, the result of a few days spent on Lundy. Mr. Charles Oldham and I were on Lundy from August 28th to September 4th, 1907, and put down traps every night in likely spots for Rats, Mice, Voles, and Shrews, but the majority of our traps were empty in the morning or had been sprung by slugs. Slugs, indeed, were very troublesome ; attracted by the bait they crawled over the traps, releasing the springs and frequently being captured, possibly early in the evening before small mammals had begun to feed. We thus secured few specimens of the animals we wanted, though the runs of mammals were abundant in some places ; winter trapping would probably be more productive. January 22nd, igo8. 2 Coward, Some Notes on the Mammals of Lundy. Lundy Island, lying about 12 miles N.N.W. of Hart- land Point on the North Devon coast and over 30 miles south of the coast of Pembroke, is a granite and slate tableland of about 3^ miles from north to south and less than a mile from east to west at the widest point. It rises to about 450 to 500 feet above the sea and is sur- rounded by steep and weathered cliffs, except at the southern end where there are tv/o beaches — on either side of a narrow neck of land — that on the east being the only one available for landing purposes. From this beach a steep lane ascends a sheltered combe, where there are a few small trees and much thick undergrowth, cultivated ground and the walled and terraced gardens round the residence of the owner, the Rev. H. G. Heaven. We set most of our traps in the bracken and bramble-covered banks of this lane and, by permission, in Mr. Heaven's kitchen -gardens. The vegetation on the eastern and more sheltered slopes is much more luxuriant than on the west; the old turf banks are thickly tangled with bramble, fern, honeysuckle, and other plants, and in small combes bracken and osmunda grow to a great height ; ling and heather is thicker and finer on the eastern than on the more exposed western cliffs. The trees — mostly ash, sycamore, willow and mountain ash — have been planted within recent years, and are small and insignificant. Camden (2) says — "Trees it hath none but stinking Elders," and T. V. Wollaston, so recently as 1845 (3), declared that it "has not so much as a single tree to boast of" This is not the case to-day; though there are no large trees, the combe referred to, has been well planted, and the trees appear to be healthy. At the southern extremity is a slate islet, cut off from the mainland at high tides only, which shelters the bay from the south ; it is called Rat Island, and is covered Manchester Memoirs, Vol. Hi. (1908), No. C 3 with a thick cushion of coarse grass through and beneath which are numerous Rat runs and burrows. The earHest reference to this islet under the name Rat Island, which I have been able to find, is in a manuscript journal of a friend of Benson's, one time lessee of Lundy, and a notorious character in connection with its dark history. I have not seen the original, but an extract is quoted by Chanter which indicates that the name was in use in 1752. Various walls, ruins of cottages and enclosures, show that at different times much of Lundy has been under cultivation, but at the present day the farms, cottages, and cultivated ground are all at the southern end ; the greater part of the island is rough moorland, where a few cattle are grazed. " The indigenous terrestrial mammalia," says Chanter, "are represented by two animals only — rats and rabbits, both of which abound. The old English black rat, mus rattus, is the indigenous and until recently was the only species on the Island ; but of late years the Norway, or brown rat, has found his way there, most probably from some shipwrecked vessel, and bids fair to exterminate the native breed." On the next page he contradicts his previous statement by adding a third species. " The shrew mouse is also found ; but no other mice, nor moles, stoat, or other vermin, nor any snakes or reptiles, exist on the Island." Mr. Heaven, however, informs us that Bats occur, but as we did not see any we can give no suggestion as to the species. The " shrew mouse " of Lundy is probably the Lesser Shrew, Sorex miniitiis, Linn. According to report, a Shrew is common ; in the banks of the lane, as well as at one or two places on the eastern slopes above the cliffs, the runs of some small mammal were very abundant. We only succeeded in capturing one Shrew, and this was 4 Coward, Sonic No/cs on tJic Mavnuah of Luudy. a Lesser — a large adult female, measuring in head and body 55mm., and tail 41mm. ; but I have particulars of two other shrews from Lundy. Mr. A. J. R. Roberts, in 1887, obtained one, which he thought was a Common Shrew, Sorcx arancus, Linn., but which he says measured from tip of snout to root of tail from 1 14 to 2 inches ; this specimen was never examined by a competent authority, but it was, judging by its size, either a Lesser or an immature Common Shrew. More recentl}' Mr. Norman H. Joy sent a Lund}- Shrew to the British Museum where it was examined and identified as Sorcx niiuiitus. We thus know that the Lesser Shrew does occur but have no satisfactory evidence that the Common Shrew is found on Lundy. If it was true in 1877 that no Mice occur on i^undy it is not true to-day; the House Mouse, Mns ninscnlns, Linn., has found its way there and is an inhabitant of the houses. We captured one in a disused farm enclosure. Mr. Joy, in a letter to the British Museum, which I have seen, says " There is also a }'ellow Mouse which is taken under hay," but he spoke from report only and had not seen an example. He suggests the Wood Mouse or Harvest Mouse. It is possible that ]\Ins sylvciticiis, Linn., does occur, but it is remarkable, if this is so, that we did not capture any in our traps, for the Wood Mouse is one of the easiest mammals to trap. We found neither the Field nor Bank Vole. The Brown Rat, Mns norvcgicns, Erxl, has not apparently succeeded in exterminating the Black Rat, AIns rattns, Linn., for both occur on the island. It has been suggested to me that the Black Rat may have been exterminated more than once and re-introduced from some of the many wrecks. Before the Trinity House alterations, when the one lighthouse standing in a high Manchester Memoirs, Vol. Hi. (1908), No. 6. 5 and central position was re-placed by lower and more powerful lights at the north and south of Lundy, wrecks were of frequent occurrence, and the majority of the Black Rats which occur in the British islands to-day are found in seaports, where they have, without doubt, been introduced by ships. While admitting the possibility of frequent additions to the Brown and Black Rat population of Lundy by refugees from wrecks, there are so many references to the Black Rats of Lundy, since the date when the Brown Rats were supposed to have first appeared, that I do not think it probable that the later introduction has ever succeeded in entirely driving out the other. Chanter quotes from Camden (2) that " the whole land swarms with rabbits and black rats," but in the 1594 Latin and 1637 English editions, which I have consulted, there is no mention of Rats ; I fancy from the modernised wording of Chanter's quotation that it must be taken from a more recent edition, which some editor has tampered with. The earliest reference to Rats which I have found, is in the same MS. journal which first mentions Rat Island, referring to affairs in 1752. " Had it not been for the supply of rabbits and young sea-gulls our table would have been but poorly furnished, rats being so plenty that they destroyed every night, what was left of our repast by day." This quotation is extracted from Chanter's " Lundy Island " and not from the original, and from the same source I have taken the words of the Rev. Thomas Martyn of Cambridge, who gave evidence about the island in Chancery proceedings in 1776. " It was so overrun with rats and rabbits, that any crops which might be produced thereoff, would, as he apprehended, be infallibly devoured by them." 6 Coward, Some Notes on the Majninals of Lundy. Francis Grose, who according to Chanter, described the island in 1775, though the reference is in vol. VI., which was published in 1785 (4), is the first to refer to the Black Rat specifically. " Rats are so numerous here as to be very troublesome ; they are all of the black sort ; the great brown rat which has extirpated this kind all over England, not having yet found its way into the island of Lundy." Chanter further tells us, referring to the arrival of the Brown Rat, that " Mr. Heaven, writing this present year " (either 1871 or 1877), "reports them as increasingly numerous, and the black rat nearly extinct. They principally frequent the south end, and Rat Island swarms with them. 1 hey are believed to feed largely on fish, as well as on limpets and other littoral prey. Specimens of a third variety, of a reddish or fox-colour, are sometimes seen and killed. It is called locally the red rat. It has much larger ears, and a longer and thinner tail than the ordinary rat, but in other respects resembles it, and they appear to consort together It is scarce, and is but rarely captured, but is persistent on the Island." Mr. Wollaston (3) mentions the Rats, which he says " grow to an unusually large size, and, not content with a mere tJieoj'etical existence, are amongst the first to make your acquaintance on landing, more particularly if you come, as is perfectly necessary, well laden with provisions." At night we frequently heard Rats in the Manor House garden, where we captured two young Brown Rats. We secured eight Black Rats, seven of them in or just outside Mr. Heaven's kitchen gardens, where they had practically ruined his crop of peas and had been feeding on fallen apples and other produce. Mr. J. G. Millais (5) divides AIiis rattus, Linn., into three sub-species, geographical races which, when intro- Manchester Memoirs, Vol. Hi. (igo^), N'o. . y duced artificially into any locality may interbreed and produce many intermediate forms. Three* out of the eight were more or less typical AIus rattus rattus — the Mus rattus of Linnaeus, blue-black above and slate-grey beneath, and five* were the brown form, Mus rattus alexandrinus, generally known as the Alexandrine Rat, the Mus alexaiidrinus of Geoffroy — brown on the upper parts and with white bellies. This Alexandrine Rat, though the examples captured could hardly be called red or foxy, is probably the mysterious Red Rat. This species, however, is very variable, and examples from the Medi- terranean basin are usually ruddy : introductions by ships from the Mediterranean might easily be called red. We set traps on Rat Island on one day only, but though the majority were sprung we only captured a single example, a large male A/Ius rattus akxandrinus. The general colour of the upper surface of the five examples of AIus rattus akxandrinus, four of which are females, varies from "wood-brown "** to "broccoli-brown" on the flanks, but the brown hair is so interspersed with glossy grey, black-tipped hairs that the whole upper surface has almost a "sepia "or dark brown appearance according to the light. On the flanks the colour is "smoke-grey" with a slight suggestion of "lavender-grey." The bellies, breasts, and underparts generally are whiter in the four females than in the old male, where they have a decided yellowish tinge. The general colour of the three darker examples — all males of the " Old English " type, Mus rattus rattus — is dark "slate-grey" shading into "olive-grey" on the belly. There is a suspicion of brown but the black and grey hair so predominates that the brown is almost entirely * See Table of Measurements at end of Paper. ** The colour terms used are taken from Ridgway's "Nomenclature of Colors," 1886. 8 Coward, Some Notes on the Mannnals of Lundy. lost. Mr. Millais describes the vibrissas as black, but in these examples there are brown and grey hairs as well as black ; his statement that the ears are naked is not correct ; they are covered with short hair on both the outer and inner surface. Even if we accept the statements of Grose and Chanter as evidence that Mus rattiis was the Rat of Lundy prior to the date at which Mns norvegicus arrived, we have no proof that it is, as Chanter calls it, indigenous. Apart from the supposition, believed by most authorities to be proved, that the Black Rat has only inhabited England for a few centuries, I must call attention again to the fact that Black as well as Brown Rats constantly reach our ports. We have in these eight examples two distinct types and no intermediate forms, suggesting a question, which, however, we cannot answer without reference to a large range of specimens ; do the two types on Lundy breed true? If this, in the future can be shown to be the case, we shall conclude that one or other or both types have quite recently been introduced, for in most cases where the sub-species live together we find these intermediate forms. A number of examples caught in the Liverpool Docks, which I examined, showed the brown upper parts of Mns rattns alexcxndriniis and the smoky under surfaces of Miis rattns rattiis. The large range in the British Museum includes all manner of variations, and from the same locality are white and dusky bellied Alexandrine Rats. As a rule the older Rats show a yellow tinge on the belly, but though many young examples are very white underneath, some are distinctly dusky. The statement, then, made by Mr. J. LI. W. Page (6) diat Lundy " is the last refuge of the Old English black rat, which still inhabits Rat Island ; indeed till about fort}^ Manchester Memoirs, Vol. Hi. (1908), No. 0. 9 years ago it was the only species on the island," is mis- leading. The Black Rat occurs and has occurred regularl}' or occasionally in many localities in our islands ; it is not a native, and therefore reached Lundy on shipboard, where it has been noticed from time to time for at least 150 years, but the island can hardly be called its last refuge. The melanic variety of LIiis norvcgicus, formerly known as liliis hibcriiicits, Thompson, was recorded by H. J. Charbonnier (7) ; he received an example in November, 1891, which had been shot on Lundy. Rabbits are mentioned in the earliest accounts of Lundy ; in an Inquisition made in 1274, the annual take of Rabbits is estimated at 2,000, 5/6 per 100 skins being the value, as the flesh was not sold, and in an even earlier 13th century deed they are also mentioned as a valuable asset. Later we find frequent references to " Connies in great store," " conies very plentiful," and " stores of conies." They are still plentiful, especially on the west coast, where the thrift-grown turf is honeycombed with burrows. In the spring many of the burrows are the homes of puffins, but at the time of our visit the Rabbits were in sole possession. Chanter's reference to Seals is as follows : — " Seals frequent the Island in considerable numbers. The only species identified is the common spotted seal, PJioca vitulina. No less than five have been killed at one time in the Seal Cavern, which is their principal place of resort ; but they have much diminished during the last few years, owing to their reckless persecution b}- the crews of pilot and tug-boats." Page (6) refers to " PJioca vitulina, or the grey seal," and adds, "there is one fine old fellow who cannot be caught. He is called by the islanders ' Ponto,' and they say he is lO Coward, Some Notes on the Mmmnals of Lundy. ' as large as a young horse.' " His use of the name " grey seal," coupled with the scientific name of the Common Seal, shows that, like Chanter, he was not aware that the larger species might occur, but unless "Ponto" was an island myth, like the Great Auk which was reported from Lundy, an animal " as large as a young horse," must have been Halichanis grypiis (Fabr.). It is possible that the Common Seal occurs on the Lundy coast, but neither Chanter nor Page tell us by whom it has been identified. We saw three Seals, two basking on rocks immediately below the old fog-signal battery, and the third swimming near the same rocks, and on the same day others were observed at the north end of the island. One Seal remained on a stack until the rising tide washed over it, and we were able to examine it closely with our glasses ; there was no doubt about the species, it was too large for a Common Seal, and had the flattened head and long snout of the Grey Seal, Halichoerus grypus. The second, though a smaller animal, was of the same species, and the third, which we only saw imperfectly, was, as it was with the others, probably a Grey. The Grey Seal is the Seal of the Scilly Islands ; there is a colony on the Pembroke coast, and it is more of a cave and rock haunting species than the Common Seal. The caves of Lundy are suitable breeding haunts for this big Seal. It is not easy to estimate the size of any animal, but we thought that the Seal on the stack would measure about 8 feet in length. When we first noticed it, it had evidently recently left the water, and looked very dark, but light markings appeared as its coat dried. It was mottled with blue-black and grey on the back, and was much lighter on the belly, which it exposed fully to view when it rolled over and dozed, lying on its back. Its Manchester Memoirs, Vol. Hi. (1908), No. 0. 11 hind flippers were extended somewhat stiffly behind, their inner surfaces meeting, and when the animal was on its side they were raised considerably ; its tail was held at right angles to the long axis of its body. The fore- flippers were frequently held or rubbed together, like a man rubbing his hands ; occasionally one was waved in the air, or was used to scratch its face or other parts of its body. It was apparently annoyed by the splashing of the incoming tide, raising its head frequently and looking round, and shifting its position to a slightly dryer part of the rock, but it did not leave until the water was swirling round it. Then it bumped heavily along the rock until the fore part of its body overhung the water, when it slipped rather than dived into the sea, almost without a splash. Mr. T. V. Wollaston, who twice visited the island to study the Coleoptera and published accounts of his visits in the " Zoologist" for 1845 and 1847, was struck with the similarity of its insect fauna to that of Wales ; he found many beetles which at that time were only known to occur in Wales and had not been found in Devon (8). The later observations of Mr. F. Smith and the recent work of Messrs. Norman H. Joy and J. R. le B. Tomlin (9) have added much to our knowledge of the Coleoptera ; many of the species unknown in Devonshire in the forties have since been discovered there, and Mr. WoUas- ton's theory is no longer accepted. The coleopterous fauna is, however, remarkable ; Dr. Wallace (10), after mentioning the two beetles then known to be peculiar to the island — Ceuthorhynchus contractus \zx.pallipes. Crotch, and Psylliodes luridipennis, Kuts., remarks about them : — " Still more curious is the occurrence of two distinct forms (a species and a well-marked variety) on the small granitic Lundy Island in the Bristol Channel. This 12 Coward, Some Notes on the Mammals of Lundy. island is about three miles long and twelve from the coast of Devonshire, consisting mainly of granite with a little of the Devonian formation, and the presence here of peculiar insects can only be due to isolation with special conditions, and immunity from enemies or competing forms." It would be unwise, considering how slight is our knowledge of the mammalian fauna, to make definite statements, but if it can be proved that the Shrew of Lundy is the Lesser and not the Common Shrew and that there are no Voles, we shall, coupling this fact with its peculiar Coleoptera, conclude that the island has been long isolated. We naturally think of the conditions in Ireland and the Isle of Man, where the Lesser Shrew but not the Common Shrew is found and where Voles are absent, though on both these islands the sub-specific form of the Stoat occurs and on Lundy no Mustelid is known. The comparison of the sea-depth round these islands does not throw much light on the subject. The depth between Lundy and the English and Welsh coasts exceeds 20 fathoms, but between the Isle of Man and England it is less than 20 fathoms, whilst between Man and Ireland there is an ocean valley of over 50 fathoms. We cannot, however, estimate the ancient depth of the Irish sea east of Man, for it is silted, owing no doubt to the action of the meeting tides which are held responsible for the coast erosion in Morecambe Bay. Further researches in this and other branches of natural history would probably amply repay the worker, and add greatly to our knowledge of this isolated and interesting island. Manchester Memoirs, VoLln.{igo^),No.^. 13 Measurements of Lundy Black Rats, Mus rattus, in mm. No. Sub-species. Sex. Head and Body. Tail. Hind foot. Ear. c.&o. 2 Mus rattus alexandrinus ? 198 227 36 24 3 >» )> >> ? 170 198 36 22 8 )> )) j> ? 177 196 38 22 9 )) )5 )) ? 167 201 36 22 10 J1 >> )) $ 199 234 37 25 5 „ „ rattus 6 188 208 38 24 6 5) 5> )> 6 209 233 40 25-5 7 )) 5> >) 6 ^95 201 37 24-5 Average 19775 175-5 219 205-5 38 2475 22'i^ 365 14 Coward, Some Notes on the M animals of Lundy. BIBLIOGRAPHY. 1. J. R. Chanter. "Lundy Island— A Monograph, 1877." Originally contributed to the Devonshire Association in 187 1 and printed in the Transaction': for that year. Enlarged and revised, in book form, in 1877. 2. W. Camden. "Britannia," 1586. First English Edition, 1 6 10, Editions referred to, 1594 and 1637, p. 202. 3. T. V. WoLLASTON. Zoologist, 1845, pp. 897, 900. 4. Francis Grose. " The Antiquities of England and Wales," 1773-1790. Vol. VI., 1785, p. 194. 5. J. G. MiLLAis. Zoologist, 1905, pp. 201-207. 6. J. Lloyd Warden: Page. "The Coasts of Devon and Lundy Island," 1895, PP- ^93' ^94- 7- H. J. Charbonnier. Irish Naturalist, 1892, p. 172. 8. T. V. WoLLASTON. Zoologist, 1847, P- 1753- 9. Norman H. Joy and J. R. le B. Tomlin Efttomologisfs Monthly Magazine, 2nd series, XVI., 1905, p. 274; XVII. , 1906, p. 156 ; XVIII., 1907, pp, 6, 27. 10. A. R. Wallace. "Island Life," 2nd edition, 1892, pp. 353> 354- PROCEEDINGS OF THE MANCHESTER LITERARY AND PHILOSOPHICAL SOCIETY. Ordinary Meeting, October ist, 1907. Professor H. B. Dixon, M.A., F.R.S., President, in the Chair. The thanks of the members were voted to the donors ot the books upon the table. The following were among the recent accessions to the Society's Library : ^'- Reports of the Conunission... for the Investigation of Mediterranean Fever^^ Pts. 6, 7 (8vo., London, 1907), presented by the Royal Society of London; '■^ Ha7idbook of American Indians, NortJi of Mexico," edited by F. W. Hodge, Part L (8vo, Washington, 1907), presented by the Bureau of American Ethnology ; " Catalogue of the Gleave Bro7it'e Collectio7i at Moss Side Free Library" by J. A. Green (8vo., Moss Side, 1907), presented by the Manchester Public Library ; '■'■ Astrographic Catalogue igoo-o. Oxford section Dec. + 2^ to+j2° "...[prepared] under the direction of H. H. Turner... vol. 2 (4to., Edinburgh, 1906), presented by the University Observatory of Oxford ; " The Licensed Trade," by E. A. Pratt (Svo., London, 1907), presented by the author; ^^ Collected Mathematical ]Vorks of G. TV. Hill," vol. 4 (4to., Washington, 1907), presented by the Carnegie Institution; "Batch Genea- logica," by T. W. Balch (4to., Philadelphia, 1907), presented by the author; ^'■Festschrift Theodor Curtius zxmi 2^ flihrigen Doktor-Jubildiun gewidmetP Arbeiten...von G. Bradig [and others] (Svo., Heidelberg, r907), presented by the Chemisches Institut der Univ. Heidelberg; '■'■ Flora Capensis," ed. by Sir ii Proceedings. {^October ist, igoj. W. T. Thiselton-Dyer, vol. 4, sect, i, parts 2, 3. (8vo, London, 1905 and 1907), purchased ; " The Advejittaes of Hadji B aba of Ispahan" [by J. Morier] transl. from English into Persian (8vo., Calcutta, 1905), presented by the Asiatic Society of Bengal ; " The Phalloids of Australasia" (8vo., Cincinnati, 1907), '■^ The Nidulariaceae or ^ Bird's-nest JFungi,''" (8vo., Cin- cinnati, 1906), ^^ The Tylostomeae'" (8vo, Cincinnati, 1906), by C. G. Lloyd, presented by the Lloyd Library of Cincinnati ; "Zi? Opere di Galileo Galilei" ed. naz., vol. iii., parte 2 and vol. xix. (4to, Firenze, 1907), " Ti-enf atmi di Studi Galileiani," by A. Favaro (4to., Firenze, 1907), presented by the Italian Embassy ; " The Comrntrcial Possibilities of West Africa" by Viscount Mountmorres (8vo, Liverpool, 1907), presented by the Liverpool University Listitute of Commercial Research in the Tropics. The Secretary exhibited to the members an engraved portrait of John Dalton, a lock of Dalton's hair, and a portrait of Thomas Young, formerly Secretary of the Royal Society, engraved by Adcock, from the painting by Sir Thomas Lawrence, which were presented to the Society by Dr. F. W. Jordan. It was resolved that the thanks of the Society be accorded to Dr. Jordan for his interesting gift. The President then delivered his Inaugural Address. The Address is published in full in the "Memoirs." General Meeting, October 15th, 1907. Professor H. B. Dixon, M.A., F.R.S,, President, in the Chair. Mr. Ernest Rutherford, M.A., D.Sc, F.R.S., Langworthy Professor of Physics in the University of Manchester, 77, Wihnslow Road, Withijigton, Manchester ; Mr. George H. WiNSTANLEV, F.G.S., M.I.M.E., Lecturer in Mining Engineer- ing and Mine Surveying in the University of Manchester; Mr. H. George A. Hickling, B.Sc, Assistant-Lecturer and October ijth, ipo/.] PROCEEDINGS. iii Demonstrator in Geology in the University of Manchester ; Mr. F. H. Gravely, B.Sc, Assistant-Lecturer and Demonstrator in Zoology in the University of Manchester ; Mr. J. L. Simonsen, M.Sc, Assistant-Lecturer in Chemistry in the University of Manchester, IJ2, Barlow Moor Road, West Didsbury, Man- chester; and Mr. Julius Hubner, Lecturer in the Faculty of Technology in the University of Manchester, were elected ordinary members of the Society. Ordinary Meeting, October isth, 1907. Professor PL B. Dixon, M.A., F.R.S., President, in the Chair. The thanks of the members were voted to the donors of the books upon the table. Professor William J. Pope, P\R.S., read a paper, written in conjunction with Mr. William Barlow, P".C.S., F.G.S., entitled " The Relation between the Crystalline Form and the Chemical Constitution of Simple Inorganic Substances." The authors have applied the methods employed in their paper of October i6th, 1906, to the study of the crystalline structure and molecular condition of a number of simple inor- ganic substances such as the crystalline elements, binary com- pounds like silver iodide, potassium chloride, &:c., ammonium halogen salts and compounds of the type of rubidium tri-iodide, Rblg. In connection with the known, but hitherto unexplained fact, that the greater number of the ciystallographically examined elements crystallise in the cubic system (50 per cent.) or the hexagonal system (35 per cent.), it is pointed out that only two simple homogeneous closest-packed assemblages of equal spheres exist, and that these possess holohedral cubic and hexagonal symmetry respectively. Further, the hexagonal closest-packed assemblage of equal spheres exhibits axial ratios of the form, a : f= i : o'8i65, or a: c=\ \ i"4i42, and the iv Proceedings. {^October i^th, igoy. hexagonal elements exhibit axial ratios approximating to one or other of these values. The fact that so large a proportion (85 per cent.) of the elements crystallise in either the cubic or the hexagonal system is therefore closely paralleled by the fact that their crystal structures can be graphically represented by homo- geneous closest-packed assemblages of equal spheres in accord- ance with the authors' previous work. It is shown that the crystalline forms affected by elements crystallising in systems of lower symmetry than the cubic and hexagonal can be derived by slight distortion from one or other of the two closest-packed assemblages above mentioned ; the requisite distortion may result from molecular aggregation or from some other cause. Most of the crystalline binary compounds consist of two elements of the same valency, and, in accordance with the authors' previous conclusions, atoms of the same valency must be represented in the crystalline edifice by spheres of approxi- mately the same size. The reason is thus derived for the fact that most binary compounds crystallise in either the cubic (68'5 per cent.) or the hexagonal (i9"5 per cent.) system. Homo- geneous assemblages have, therefore, been constructed from spheres of two kinds, but of approximately equal size, which represent the crystalline structures of cubic and hexagonal com- pounds, such as Agl, KI, CaO, &c. ; it is shown that the pro- perties of these structures correspond very closely with those observed upon the crystalline materials. The dimorphism of silver iodide is elucidated by the simple manner in which the cubic closest-packed assemblage can be converted into that of hexagonal symmetry. A close agreement exists between the calculated axial ratios stated above for the hexagonal assemblage, and those observed upon the hexagonal binary compounds. The crystalline structure appropriate to such substances as rubidium tri-iodide, Rblg, thallic iodide, TIT^, &c., is derived in a similar manner to the above, and it is shown that close agree- ment occurs between the derived and observed crystal forms. By the study of such crystalline substances it can be shown that October ijtii, igo-j'.\ Proceedings. v the spheres by which the alkaH metals and the halogens are represented in the assemblages differ slightly in size, the sphere increasing in magnitude with an increase of atomic weight in the case of each of these classes of elements. General Meeting, October 29th, 1907. Professor H. B. Dixon, M.A., F.R.S., President, in the Chair. Captain Arthur Doggett, Works Secretary, Vulcan Loco- motive Works, Newton-le-Willows, 48, Gilda Brook Road, Eccles ; Mr. Harold Shawcross Leigh, Brentiuood, IVors/ey ; Mr. Theodore George Bentley Osborn, Wellbury, Richmond Road, East Jzvickenhain, Middlesex, Reginald Francis GwYTHEi^, M.A., Secretary to the Joint Matriculation Board, and Mr. Thomas Whitehead, B.Sc, Chemist to the Manchester Steam Users' Association, were elected ordinary members of the Society. Ordinary Meeting, October 29th, 1907. Professor H. B. Dixon, M.A., F.R.S , President, in the Chair, The thanks of the members were voted to the donors of the books upon the table. Dr. Henry Wilde, F.R.S., read a paper entitled, "On the Atomic Weight of Radium." Professor E. Rutherford, D.Sc, F.R.S. , read a paper entitled, " The Production and Origin of Radium." An account was given of the historical development of our ideas in regard to radium. On the disintegration theory, radium is regarded as a substance undergoing slow spontaneous trans- formation with a period of about 2,000 years. In order to account for the existence of radium in minerals of great age, it vi PpOCEEDINGS. {^October 2Qth, igoy. is necessary to suppose that radium is produced fiom another substance of long period of transformation. There is an undoubted genetic connection between uranium and radium, for investigation has shown that the amount of radium in minerals is in all cases proportional to their content of uranium. If this be the case, radium should gradually appear in a pre- paration of uranium, initially freed from radium. No such growth of radium has been observed over a period of several years although a very minute growth of radium can be easily detected. This is not necessarily inconsistent with the disintegration theory for if one or more products of slow trans- formation exist between uranium and radium, no appreciable growth of the latter is to be expected in a short interval. A search for this intermediate product has recently proved success- ful. Boltwood found that a preparation of actinium, initially freed from radium, grew radium at a constant and rapid rate. Boltwood at first considered that actinium was this intermediate product and that actinium changed directly into radium. The growth of radium in actinium solutions was confirmed by the writer, who had commenced experiments in that direction three years before. The experiments showed, however, that actinium did not, as Boltwood supposed, change directly into radium. By a special method, a preparation of actinium was obtained by the writer which showed no appreciable growth of radium over a period of 240 days. The growth of radium, if it occurred at all, was certainly less than i/5ooth of that ordinarily observed. In another case, a solution of actinium was obtained which produced radium faster than the normal. These results are completely explained by supposing that a new substance of slow transformation is present with actinium, and this substance is transformed directly into radium. This parent of radium has distinct chemical properties, which allow it to be separated from both actinium and radium. The absence of growth of radium observed in the actinium solution mentioned above is due to the fact that, by the special method, the parent of radium had been completely separated from the actinium. October 2gth, ipoy.] Proceedings. vii In recent letters to Nature, Boltwood has confirmed the results of the writer, and has devised a satisfactory method of separating the radium parent from actinium. He has shown that this new body, which he proposes to call "ionium," gives out o and /3 rays, and has the chemical properties of thorium. The Royal Society recently loaned the writer the actinium residues from about a ton of pitchblende. These residues con- tain the parent of radium, and experiments are in progress to isolate and concentrate both the actinium and ionium in these residues. The President announced that Dr. Joseph Larmor, Secretary of the Royal Society and Lucasian Professor of Mathematics in the University of Cambridge, had consented to deliver the Wilde Lecture for 1908 on "The Physical Aspect of the Atomic Theory." General Meeting, November 12th, 1907. Professor H. B. Dixon, M.A., F.R.S., President, in the Chair. Mr. John William Bews, M.A., B.Sc, Lecturer in Economic Botany in the University of Manchester, was elected an ordinary member of the Society, Ordinary Meeting, November 12th, 1907. Professor H. B. Dixon, M.A., F.R.S., President, in the Chair. The thanks of the members were voted to the donors of the books upon the table. The following were among the recent donations to the Society's Library : — " De Berekefttng, de Bouw en het Bedrijf van het Kabelnet d. Gemeente Amsterdam" Door G. de Gelder (8vo., 's-Gravenhage, 1907), " Mathematische utid viii Proceedings. {November 1 2th, iQoy. mikroskopisch-atiatomische Studien iiber Blattstellungen nebst Betrachtimgen iiber den Schaknbau der l\filioli?ien,''^ von G. van Iterson, Jun. (410, Jena, 1907), presented by the Technische Hoogeschool te Delft ; " Figures and descriptions of Catiadian Organic Remains^'' Decades i, 3, and 4. (8vo., Montreal, 1858-59), " The Fossil Plants of the Brian. ..and Upper Silurian Formations of Catiada" part 2, by J. W. Dawson (8vo, Montreal, 1882), " Contributions to the Micro-palcBontology of the Cafnbro- Silurian Rocks of Canada" by A. H. Foord (8vo., Ottawa, 1882), " A History of Neiv Briimivick Geology" by R. W. Ells (8vo, Montreal, 1887), '•'■Check-list of Canadian Plants'' by J. M. Macoun (8vo., Ottawa, 1889), '■'■ Palceozoic Fossils" vol. 3, pt. 3, by J. F. Whiteaves (8vo., Ottawa, 1897), ^^ Afesozoic Fossils," vol. i,pts. 4 & 5, by J. F. Whiteaves (8vo., Ottawa, 1900, 1903), ^^ Report on the Cambriaji Rocks of Cape Breton" by G. F. Matthew (8vo., Ottawa, 1903), '•'■Economic Minerals of Canada" by G. M. Dawson (8vo., n. pi., 1900), ^^ On the Nepheline Rocks of Ice River, British Columbia" (8vo., n. pi., [c. 1904]) and " A Landslide on the Lievre River " (8vo., [Ottawa, 1905]), by A. E. Barlow, presented by the Geological Survey of Canada ; Palceolithic Vessels of Egypt, by R. de Rustafjaell (8vo., London, 1907), presented by the author; " The History of the Collections in the Natural History T)epart- ment of the British Museum" vol. 2 (8vo., London, 1906), ^'•General Guidt to the British Musejon {Natural History)" nth ed. (8vo., London, 1906), " Guide to the Fossil Reptiles, Amphibians and Fishes. ..in the British Museum [Natural History)" (8vo., London, 1905), '•'■Guide to the Gallery of Reptilia and Amphibia in the... British Museum {Natural History)" (8vo., London, 1906), '■'•Guide to the Galleries of Mammals {other than Ungulates) in the ... British Museum {Natural History)," 8th ed., (8vo, London, 1906), " Guide to the great Game Animals {Ungulata), in the. ..British Museum {Natural History)" (8vo, London, 1907), ^^ Guide to the Fossil Inverte- brate Animals in the. ..British Museum {Natural History)" (8vo., London, 1907), ^^ List of British Seed-plants a?id Ferns" November 1 2tJi, igoj?\ Proceedings. ix (8vo, London, 1907), " Guide to lui ExJiibition of Old Natural History Books" ...{?,wo, London, 1905), "Books and Portraits illustrating the History of Plant Classification"... {^wo, London, 1906), '■'■Memorials of Linn(eus"...(2>\o., London, 1907), pre- sented by the Trustees of the British Museum. Mr. D. M. S. Watson, B.Sc, read two papers entitled respectively " The Cone of Bothrodendron munduiii (Will.)," and " On the Ulodendroid Scar." The President announced that the Wilde Medal for 1908 would be awaided to Professor Joseph Larmor. Sec.R.S., of Cambridge University, on March 3rd next, and that Professor Larmor would on that occasion deliver the Wilde Lecture on " The Physical Aspect of the Atomic Theory," and be after- wards entertained at a dinner in his honour, the particulars of which would be made known later. General Meeting, November 26th, 1907. Professor H. B. Dixon, M.A., F.R.S., President, in the Chair. Mr. Abraham Flatters, F.R.M.S., 16, Church Road, Long- sight, and Mr. Robert Henry Clayton, B.Sc, Chemist, Woodleigh, Blackfield Lane, Kersal, ALanchester, were elected ordinary members of the Society. Ordinary Meeting, November 26th, 1907. Professor H, B. Dixon, M.A., F.R.S., President, in the Chair. The thanks of the members were voted to the donors of the books upon the table. Professor Edmund Knecht, Ph.D., gave a demonstration illustrating the formation of acetylene from elementary sub- stances. X Proceedings. [November 26th, igoy. On heating a small piece of calcium on charcoal before the blowpipe, the metal readily took fire, and, after burning with a brilliant orange flame for about two seconds, sank into the mass of the charcoal. After the latter had been allowed to cool, it was broken up, when a hard lump was found which yielded acetylene on treatment with water. Mr. Julius Hubner, M.Sc.Tech., F.I.C, read a paper entitled, "New Reactions for the Characterisation of Mercerised Cotton." Mr. H. F. Coward, M.Sc, read a paper, entitled "The Direct Combination of Carbon and Hydrogen." Doubt had recently been cast, he said, on the validity of Bone and Jerdan's synthesis of methane by direct union of carbon and hydrogen, by Berthelot, Pring and Hutton, and by Mayer and Altmayer. The author, however, in recent experiments, made with small quantities of highly purified carbon, had obtained from o'l gram of carbon containing a maximum of 09 cc. of hydrogen, 100 to ]2occ. of methane by direct union with hydrogen. Ordinary Meeting, December loth, 1907. Professor H. B. Dixon, M.A., F.R.S., President, in the Chair. The thanks of the members were voted to the donors of the books upon the table. The President presented to the Society's Library copies of first editions of the following works of Hon. Robert Boyle, formerly in the possession of the Library of the old " Salford Academy " : — " Hydrostatical Paradoxes." 1666. " New Experiments touching the Relation betwixt Flame and Air." London, 1672. Manchester Memoirs, Vol. Hi. (1908), No. T- VII. The Atomic Weight of Chlorine. By E. C. Edgar, D.Sc. (Received and read /^amiary 14th, igp8.) The method used to redetermine this constant was to burn pure dry chlorine, at the tip of a quartz jet, in an atmosphere of pure dry hydrogen in a quartz " combustion vessel " ; the hydrogen chloride formed was condensed in a limb of it by liquid air. The weights of the gases burnt were found by sub- tracting from the total amounts used the weights of unburnt hydrogen and chlorine. Eight experiments were made. In six the hydrogen chloride was distilled from the " combustion vessel " into a steel bomb and weighed as a liquid. In three of these the weights of the liquid were less than the weights ot hydrogen and chlorine burnt ; in the other three the bomb leaked. In the last two the hydrogen chloride was distilled into an apparatus containing water and weighed as aqueous hydrochloric acid. As the mean of eight experiments, the atomic weight of chlorine calculated from the ratio weight of chlorine burnt weight of hydrogen burnt is 35' 1 94 ; from the ratio weight of hydrogen chloride caught - weight of hydrogen burnt weight of hydrogen burnt it is 35'i93 (atomic weight of hydrogen = i). February 6th, igoS. Edgar, The Atomic Weight of Chlorine. If the atomic weight of oxygen is taken as i6, that fif chlorine becomes 35*462 and 35'46i respectively. These numbers differ appreciably from that accepted by the International Committee on Atomic Weights, 3 5 "45, but agree very well with 3 5 '463 found by Dixon and Edgar in 1905, and with 35*461 lately proposed by Guye. Manchester Memoirs, Vol. Hi. (1908 J, No. 8. VIII. On a New Type of Dynamical Stability. By Andrew Stephenson. (Received and read January 28th, igoS.) I. A system in a position of equilibrium, and capable of oscillation about that position, may be acted on by periodic force in such a way that no oscillation is generated. If, for example, one end of a vertical stretched string is moved to and fro in the direction of the length, this imposed motion has no tendency to produce lateral vibration. In certain cases, however, it has considerable effect in intensifying an already existing oscillation ; in particular, if the imposed frequency is double that of the lateral motion, a very marked swing is magnified from the slightest initial disturbance. Another example of a similar kind is afforded by a pendulum, the point of suspension of which is subject to a vertical periodic motion : if the frequency is double that of the pendulum, any small swing is gradually magnified by cumulative action. Various instances of the double frequency effect forced themselves upon the attention of observers, and it appears to have been assumed — possibly from the simplicity of the phenomenon — that it is only in the case of double frequency that this type of disturbance has appreciable influence. Mathematical investigation has shewn, how- ever, that the effect is cumulative in the whole series of cases when the disturbance frequency is approximately 2Jr of the natural frequency of the system, r being any March ^th, igo8. 2 Stephenson, New Type of Dynmnical Stability. integer.* The intensity of the magnifying effect falls off rapidly when r is taken larger, and as our terrestrial systems are always subject to friction, it is difficult to exhibit many cases experimentally. With the pendulum the intensifying influence may be observed for several values of r without special nicety of adjustment. Our present object is to establish another very remark- able property of the non-generating type of periodic disturbance. 2. In the preceding pendulum experiments the result- ing motion is due to the combined action of the imposed force and gravity. Let us enquire as to the effect of the imposed force acting alone. To examine this question experimentally, a rod is pivoted vertically so that it is free to rotate in a horizontal plane : when the pivot is driven horizontally in a simple vibration along the length of the rod the relative equili- brium is not disturbed. If, now, the rod is displaced through a small angle, it is observed to swing about the line of the imposed motion in a period large compared with that of the pivot. All the properties of the motion may be deduced from the differential equation determining it, but here we seek an approximate treatment of the problem, based on general mechanical considerations, in order to obtain a notion of what happens more vividly than is possible from the exact solution. For this purpose we assume that a, the amplitude of the pivot motion, is small, and also that the speed of the pivot, P, is constant, and equal to F, say, throughout the path ; i.e., we assume that the body is acted on by suitable impulses applied at P at the ends of its path, being free from action in all intermediate * " On a class of forced oscillations," Quart. Journ. Math , No. 148, 1906, Manchester Memoirs, Vol. Hi. (1908), No. 8. 3 positions. We shall first obtain the magnitudes and directions of the impulses necessary to impose the motion. Let P be the instantaneous centre of rotation of a body of mass J/, and with mass centre C. If an impulse, /, acts at P in a direction making a small angle, 0, with PC^ it gives the mass centre a velocity //i/, and at the same time produces an angular velocity IJi<^\Mk'^% where h = PC d^n^ k is the radius of gyration about C. Fig. I. The velocity of P after the impulse is thus made up of the components PQ = I/M along the line of the impulse, and QR = (Ik'^/Mk'^)^ perpendicular to PC: the resultant is therefore PR. In our problem this velocity is constant (numerically), = V. PQR being approxi- mately a right angle, PQ differs from PR by a small quantity of the second order : hence the impulse I=M.PQ = MV so far as quantities of the first order are concerned. Also if RPC is denoted by d d_ SR ;r + /^" Thus to impress the required velocity F on P in a direction at an angle Q to the rod an impulse J/ F must act at an angle ^,—^9 to the rod. An impulse of double magnitude will then reverse the motion of P from Fto— V : and the imposed vibratory motion of P with constant speed V in the path AB is produced by impulses 4 Stephenson, Netv Type of Dynamical Stability. of magnitude 2J/F applied in the direction dividing the angle between the rod and AB in the constant ratio k-lJi'. It will be convenient to regard the action at either end of the path as made up of two consecutive impulses, MV, one bringing P to rest, and the second giving it the velocity towards the other end. The angular velocity at the instant between the two impulses is then equal to the mean angular velocity during the cycle of which the instant is the mid point. Consider the motion from the instant when P has been brought to rest at A by the action of the first half impulse ; let the inclination of PC \.o AB\i^ 6 and the angular velocity w. The moment of the second half- impulse about C is ^'^^^■" and the resultant change in the angular velocity FAd/(/i' + /r). If r is the time of motion to B the inclination of the rod at B is therefore e + {w+ y/id/{/i- + k^)]T, and the moment of the impulse at B - 2MV-^M + Iw + VhQl{Jr + fe)\T\ The angular velocity after this impulse is w- Vhdl{lr + k') correct to small quantities of the first order, and the inclination on reaching A again is 0+2wr. Hence the moment of the first half-impulse bringing P to rest at A is h- + k By summation the total moment applied during the motion of P from rest to rest at A is -2MV ,,,,>■ {Ir + lrf Manchester Memoirs, Vol. Hi. (1908), No. 8. 5 Hence if w' is the angular velocity at the end of this cycle, Vh . fl; 2r \/r + /&-/ i.e., the mean angular acceleration is directed towards the position of relative equilibrium, and is proportional to the angular displacement. The mean motion is therefore a simple oscillation Vh 6 = asm h^^k ,/+e (0 The actual motion is evidently of the nature shewn in the diagram {Fig. 2), in which the time is plotted hori- Fig. 2. zontally and the angular displacement vertically : the two boundaries are sine curves and the successive vertices are equidistant in time. The preceding synthetic investigation brings out the essential characteristics of the motion. The impulses are constant in magnitude, and the effect of any impulse in changing the angular velocity is proportional to the angular displacement ; secondly, the angular displacement at B algebraically exceeds half the sum of the two at A on either side, by an amount proportional to the displace- 6 Stephenson, New Type of Dynamical Stability. ment ; whence it follows that the impulsive moment in any cycle from rest to rest at A is always directed towards the central line of motion AB, and varies directly as the displacement — the conditions determining a mean motion of simple oscillation. Such considerations tend to familiarise the motion, but the quantitative results may be obtained by a more analytical method, which will now be given for the sake of comparison. Let 0 be the inclination of PC to AB on starting from A after the impulse, and w the angular velocity at the same time* ; also let 0i, Wi be the values of these quantities after the impulse at B, and ^-^^ w the values after the succeeding impulse at A. On starting from A the velocity of the mass centre has components ( V- /zwsiny, /^wcosO) along and perpendicular to AB. After the impulse at B the velocity is (- F-/^wiSinf^i, //wicosyj). Hence if (A', Y) the impulse at B XI M= -2V- /liwiSinOi - wsinG) V/A/= /i{w j^cosdi - w cos d). Again, considering the motion about the mass centre we have Mk\u)i - w) = (.Y sin 6, - Fees d,)/i .'. k-{toi - w) = - 2 V/isindi - /i-{u>i - uj)cos{Oi - d), and to the required degree of approximation (/^- + ^■-j(wi - w) = - 2 V/id^ . . . (i.) Similarly, considering the succeeding impact at A we have {/r + A'){w.,-uj,)=2FM, . . . (li.) .\{/r + /i%o.,-io) =2F/i{e,-6,) . . (iii.) * It must be remembered that w here has not the same meaning as in the preceding. Manchester Memoirs, Vol. Hi. (1908), No. 8. 7 Now, during the cycle, the mean angular velocity = — (ii» + (.>,) Vh „ Vh \ Vh h" + k-'J h' + k'^ ' ' ' ^^^'^ Similarly, during the succeeding cycle, the mean angular velocity / Vh \ Vh ^ , , Therefore, from (iv) and (v.), the change in mean angular velocity . Y V/i \ Vh .„ „, . • . from (iii.) Vh , s ( Vh V/« a^ . • . from (i.) Vh W ^ change in mean angular velocity in cycle 2r_ _ / Vh V 2r \/r + hy when small quantities of the second order are neglected. Thus the mean angular acceleration is directed towards the position of equilibrium, and is equal to (-p — 73) x the angular displacement — the result obtained previously. It is of interest to compare this case of constant pivot speed with the motion when the pivot has a simple vibra- 8 Stephenson, New Type of Dynamical Stability. tion of small amplitude a, and frequency ;/ per 27r units of time. The equation of motion is then % + —, , an-co% nt 6 = o h- + K- and the solution* when a]i\{Ji--\-k-) is small, is approxi- mately "-^KTi^l^'^') • • • <^* It is evident that (i) and (2) are of the same type, a?i in (2) being the maximum velocity of P in its path. We have thus proved that when the amplitude of the pivot motion is small, the body swings in a simple vibra- tion of frequency proportional to the frequency and to the amplitude of the applied motion. 3. Now consider a body free to rotate about a hori- zontal pivot, and set in the position of unstable equilibrium : what will be the effect of a vertical oscillation of the pivot on the stability of the equilibrium ? In the position inclined to the vertical at an angle Q, the mean angular acceleration due to the imposed motion is \\-7T, — rJ ^ inwards, from (2); while the outward - \h- + li-J acceleration due to gravity is ^ B. The resultant is therefore a-rrh \ h ^ and the acceleration is always towards the vertical if {anf>2g{lr + k')lli. Thus the inverted pendulum is rendered stable by a small simple vertical oscillation of the pivot of maximum velocity greater than j2g{lr + F)llL * The investigation is given in a paper "On Induced Stability," /"/), No. ^. 9 When this condition is satisfied, the motion about tiie vertical is simple vibratory of frequency / f a'-h-h } h / V per 2tr units of time. To illustrate these results experimentally, a uniform rod of length 39"6 cm. was pivoted at one end, and the pivot was moved in an approximately simple vibration of amplitude 3'85 cm. With an applied motion of frequency I r2 per sec, the period of the small oscillations about the vertical was found to be r64 sec. The abo\'e formula, (3), gives r58 sec. The 4% difference may be attributed parti}' to the effect of friction in lengthening the period, and partly to error in the determination of the pivot frequency. If the imposed motion is slightly inclined to the vertical, it is observed that the pendulum makes small oscillations about a position much more markedly oblique in the same direction. This effect can be explained very simply. Let the inclination of the applied motion be |3, and that of the mean position of the pendulum y. The accelerations due to the applied motion and gravity in this position must be equal and opposite ; i.e., -K/r + Zi", and therefore / ajih y, p. gh /~'v 1 1 •...2/, I t d'/rh J 1 hus y is large compared with /3 when ;/ is near the limit necessary for stability.* Finally, it may be noted that the stability effect still * For the determination of the amplitude of the forced oscillation about the mean position, reference may be made to § i of the paper on " Induced Stability '.' already quoted. 10 Stephenson, Nnv Type of Dynamical Stability. holds when the rod is supported by a double joint so that it has complete freedom of motion about the vertical. 4. The particular case of dynamical stability investi- gated above is an example of a general type. If any system fixed by one coordinate is statically unstable in a position of equilibrium, that position is rendered stable by the action of a periodic disturbance a[)plied in such a way as to generate no motion about equilibrium. The main- tenance of the stability here does not necessarily demand an impressed motion : in the case of the inverted pendu- lum, for example, a periodic variation in gravity would have the same effect as the vertical oscillation of the pivot. Some types of steady motion are also rendered stable by a non-generating periodic disturbance* ; thus a top rotating at a speed too low for stability is maintained about the steady state by a vertical oscillation of the point of support. It is possible that this method of ensuring the stability of a steady motion may be of service in special cases where the more usual devices are not applicable. In the problem of mechanical flight the great difficulty lies in obtaining longitudinal stability at slow speeds ; if an aeroplane system is started in steady motion, a small disturbance results in a pitching oscillation, which con- tinues with increasing violence until finally the glider is overturned. The mathematical investigation of the effect of the non-generating periodic disturbance which is illustrated in this paper, was undertaken with the view of its possible application to a mechanism whereby stability in gliding would be automatically ensured. In such a case the motion is of a more complex character, involving the interaction of several co-ordinates : it is hoped to give a general examination of the problem later. * loc. cit., g 2 and 3. Manchester Memoirs, Vol. Hi. (1908), No. ^. IX. "A Method of Counting the Number of a Particles from Radio-active Matter." By Professor E. RUTHERFORD, F.R.S., AND H. Geiger, Ph.D. ( Received and read Febfuary nth, igoS.) The total number of a particles ex[)elled per second from one gram, of radium has been estimated (Rutherford Phil. Mag., Aug. 1905) by measuring experimentally the total positive charge carried by the a rays from a thin film of radium, on the assumption that each a particle has the same charge as an ion produced in gases. If the a particle is an atom of helium, it is necessary to assume that each a particle carries twice the ordinary ionic charge. The need of a method of directly counting the number of a particles shot out from radio-active matter has long been felt in order to determine with the minimum of assump- tion the charge carried by the a particle and also the magnitude of other radio-active quantities. It can be calculated that an a particle expelled from radium produces about 80,000 ions in a gas before its ionizing power is lost. With very sensitive apparatus, it should be just possible to detect the ionization produced by a single a particle by electrical methods. The effect, however, would be small and difficult to measure with accuracy. In order to overcome this difficulty, we have employed a method which automatically increases the ionization produced by an a particle several thousand times and so makes the electrical effect easily observable March 14th, igo8. 2 Rutherford, a Particles from Radio-active Matter. with an ordinary electrometer. This is done by making use of the property discovered by Tovvnsend, that an ion moving in a strong electric field in a gas at low pressure, produces a number of fresh ions by collision with the gas molecules. If the electric field is adjusted nearly to the value required for the passage of the spark, a single ion generated in the gas by external agencies, produces in this way several thousand fresh ions by collision. In the experimental arrangement, the testing vessel consists of a brass tube 60 cms. in length, along the axis of which passes a thin insulated wire attached to the electrometer. With a gas pressure of about 2 cms, a potential difference of about 1,000 volts between the brass tube and the wire is required. The a particles are fired down the tube through a small hole at the end of the tube about 2 mms. in diameter covered with a thin plate of mica. In order to use a narrow pencil of a rays, the active matter in the form of a thin film on a surface about one square cm; in area is placed in an exhausted tube which is a prolongation of the testing vessel. The distance of the active matter from the hole is usually between 50 and 75 cms. and the amount of active matter adjusted so that from six to ten a particles are fired through the hole per minute. The effect of the a particle entering the testing vessel is shown by a sudden throw of the electrometer needle. Under good conditions, this throw is about 50 divisions using an electrometer which has a sensibility of 300 divisions per volt. By observing the number of throws of the electrometer needle, we can count the average number of a particles shot through the opening per minute. The total number fired out by the active matter can be calculated from the known area of the opening and the distance of the latter from the active matter. Preliminary observations show that the number Manchester Memoirs, Vol. Hi. (1908), No. 0. 3 of a particles counted by this method is of the same order as the calculated number, but special experiments are in progress to determine with accuracy the value of this important constant. By counting at intervals the number of a particles expelled per minute, we have been able to obtain the curves of decay of activity of a plate coated with radium C or actinium B. The a particles from a constant source are shot out at irregular intervals. The time interval between the entrance of successive a particles has been observed over a long interval, and the results show that the distribution curve with time is similar in general shape to the probability curve of distribution of the velocity of molecules in a gas. Further observations, however, are in progress to determine the distribution curve with the accuracy required for comparison with the mathematical theory. Manchester Memoirs, Vol. Hi. (1908), No. t. VII. The Atomic Weight of Chlorine. By E. C. Edgar, D.Sc. (Received and lead [auuary 14th, igo8.) The method used to redetermine this constant was to burn pure dry chlorine, at the tip of a quartz jet, in an atmosphere of pure dry hydrogen in a quartz " combustion vessel " ; the hydrogen chloride formed was condensed in a limb of it by liquid air. The weights of the gases burnt were found by sub- tracting from the total amounts used the weights of unburnt hydrogen and chlorine. Eight experiments were made. In six the hydrogen chloride was distilled from the " combustion vessel " into a steel bomb and weighed as a liquid. In three of these the weights of the liquid were less than the weights ot hydrogen and chlorine burnt ; in the other three the bomb leaked. In the last two the hydrogen chloride was distilled into an apparatus containing water and weighed as aqueous hydrochloric acid. As the mean of eight experiments, the atomic weight of chlorine calculated from the ratio weisrht of chlorine burnt weight of hydrogen burnt is 3 5' 1 94 ; from the ratio weight of hydrogen chloride caught - weight of hydrogen burnt weight of hydrogen burnt it is 35"i93 (atomic weight of hydrogen= i). February 6th, igoS. Edgar, The Atomic Weight of Chlorine. If the atomic weight of oxygen is taken as i6, that •of chlorine becomes 35'462 and 35'46i respectively. These numbers differ appreciably from that accepted hy the International Committee on Atomic Weights, 35*45, but agree very well with 35463 found by Dixon and JEdgar in 1905, and with 3 5 '461 lately proposed by Guye. Manchester Memoirs, Vol. Hi. (1908), No. 10. THE WILDE LECTURE. X. On the Physical Aspect of the Atomic Theory. By Professor J. Larmor, Sec.R.S. Ddive7-ed March 3rd, igo8. When Descartes proceeded methodically to shake himself free from the trammels of the scholastic philosophy, and to reconstruct the content of his knowledge on what is essentially the modern basis, he found among other things — some of them now fantastic — that it was unin- telligible to suppose that matter could act where it was not, i.e., could produce an influence in regions with which it was not in continuous structural connexion. So powerfully did this feeling dominate his thought, that he appears to have been unable to form any conception of mere empty space as distinct from some mode of occupation of it : to him, space was 3. plemim, the seat of the processes of communication between the sensible objects which it contains. Direct interaction of these objects across distances, with mere nothingness between, was not a satisfying account of the relations between the apparently discrete masses which constitute our sensible universe. The modern idea of an aethereal medium, as a means of transmission of physical influences from mass to mass, receives its first systematic exposition in his physical writings. The Sun is for him the centre of a great aethereal vortex, by which the planets are swept round in their orbits ; light consists of impulsion or pressure propagated through the fluid plenum. An attempt is March 2Sth, igo8. 2 LarmoR, Physical Aspect of the Atomic Theo7y. carried through to reconstruct the phenomena of physics and physiology on a basis of mutual connexion — thereby starting afresh the aspiration which is fundamental to all scientific instinct, the effort to push to the utmost the unravelling of rational foundations of the scheme of things in which we subsist. And, whereas in Descartes' time there was little to go upon, except the imagination applied to the common facts of experience, now there are the vast and growing accumulations of ascertained experimental knowledge in the various Sciences, affording a most urgent stimulus towards the continued cultivation and improvement of general syntheses ; these in turn react as the ever present incitement to the further pursuit of scientific experiment into regions economically devoid of profit. The Cartesian system of celestial vortexes had been absorbed into common modes of thought, as a natural and intelligible feature in the cosmogony, when the precise observations of Kepler and the deductions of Newton came to replace this obvious mode of representa- tion by new but exact principles whose foundations were entirely concealed from view. It is not easy for us now to imagine how strange must have been the idea that the planets were drawn inward to the Sun by a direct pull across space, depending on nothing but their distance apart, — by a force which was postulated to act quite irrespective of whatever obstacles might intervene between them. To prepare for the unimpeded operation of direct forces across space such as Newtonian gravitation, the aether of Descartes — resisting medium so-called in this connexion — which had to carry round the planets in its vortex, must be rigorously abolished : and space appears again as empty. Even the intellect of Huygens — whose vast range of achievements has been largely Manchester Memoirs, Vol. Hi. (1908), No. 10. 3 masked by the contemporary presence of Newton — seemed unable to accept the new doctrine in its full scope. To a mind like his there could remain no question about the chief Newtonian deductions : the evidence was conclusive that the interactions through the aether of bodies far apart in comparison with their magnitudes, and with nothing between, must somehow adjust themselves into the gravitational law of attraction. But he was unable to understand how the complex mutual influence of masses near together could possibly, in all cases without exception, resolve itself into a result so uniform and so simple. And to this day we remain largely in the position of Huygens with regard to this subject. The evidence, which in its beginnings enabled the genius of Newton to detect and develope his cosmical system, has of course long ago become overwhelming. Yet why is the gravita- tional attraction of a particle of matter sunk at the centre of the Earth entirely unaffected by all the intervening mass ? We do not know, any more than Newton did, how this action is transmitted. We may take refuge in the idea that the nuclei in the aethereal medium, which constitute the cores of the fields of activity known to us as material atoms, must even in the densest matter occupy a space absolutely infinitesimal compared with the whole region of aether, and so not obstruct or modify the transmission of the gravitative influence. To get play for rational conceptions, we are thus thrown back on the atomic theory of matter, and that in its more modern physical aspect, to which it is now time to pass on. It does not appear that Descartes was able to penetrate to any idea of the relation of the cosmical vortex to the atoms of the material bodies which it carried round in its grasp ; they were merely like ex- 4 Larmor, Physical Aspect of the Atomic Theory. traneous dust or mist whirled in the wind. For an adequately exact type of unifying conception of the relation between matter and aether, of their structural connexion, science had to wait until the middle of the nineteenth century. The profound analysis of Helmholtz had revealed the unexpectedly simple scope of the principles determining the interactions of vortexes in fluid — one of the most brilliant of the achievements of mathematical reasoning, whose highest function must always be to condense the unmanageable mass of relevant particulars into the practicable limits of general principles. His main result was that, in the entire absence of friction in the fluid, each vortex ring would be a permanent state of motion, capable of temporary modification (distortion, vibration, etc.), through inter- action across the fluid with other vortexes which come within its range, but always in the end recovering its original condition, and thus retaining its individuality through unlimited time. We can well imagine the keen interest excited by Lord Kelvin's rapid apercu that such vortexes may represent in essential features the atoms of matter. For here we have a type of atom that is not something foreign to the aether, merely immersed in it and pushed about by it, but a permanent located whirl or stable state of motion which subsists in the aether itself, and is of its very essence. Here was suggested a mode of unification of a duality previously unresolvable ; and we can appreciate the zeal with which the problem of the investigation of this vivid image of one of the fundamental modes of inter- connexion in the scheme of nature was attacked by mathematical physicists. Its development, in which alongside the name of Helmholtz that of Lord Kelvin will ever stand, has constituted, as we all know in this Manchester Memoirs, Vol. Hi. (1908), No. 10. 5 place, a new science, that of abstract hydrodynamics, which analyses the interaction of uniform inertia and simple fluid pressure, and is in itself one of the most elegant and perfect constructions of modern mathematics. As a result of these thorough investigations, we are now more familiar with the limitations of the so-called vortex theory of atomic constitution, than with the initial successes of this mode of representation of physical reality. But limitation ought not to be taken to imply failure. Human reason is finite in its potentialities : it is not competent to frame a picture of the activities of the cosmos, of which it is itself a part, such as can bear Comparison with actuality throughout the whole range of phenomena. It is of course absurd, as we are often reminded with much insistence, especially in recent years, to imagine that a material atom is merely a vortex ring in fluid ; but, on the other hand, we can never know any object, even an atom, intrinsically, but only through its relations with other objects, and the picture of atoms as motional configurations subsisting in some way in the universal plenum, and not merely objects foreign to it, is possibly the greatest expansion which our modes of thought on these matters have received since Descartes ; and it has come to us, or has at any rate been made definite, through the vortex illustration. This procedure, the study of the relations of the universe by the construction of working models, easily apprehended as a whole, is not restricted to external nature. A considerable part of present activity in abstract mathematics seems to consist in the construction of schemes of representation, such as will elucidate the inner scope and connexion of the processes of mathe- matical thought, involving analysis of the ideas of number and magnitude, limit, infinity, etc. It is signifi- 6 L ARMOR, Physical Aspect of the Atomic Theory. cant that in both cases some kind of atomism has been a mental necessity, as it was in the eadiest Greek inquiries. We have recalled that, in order to make way for the principle of gravitation, Newtonians were compelled to- clear the celestial spaces of the " resisting medium " which constituted the aether of Descartes. But that by no means implied any belief that gravitation did not require a medium for its transmission. Towards the end of his life, Newton allowed himself to set down formally in the famous series of " Questions " appended to the second edition (1717) of his "Opticks,"* his speculations on this and related subjects concerning the constitution of matter^ pervaded as they were by constant suggestion of the vibratory motions which constitute heat, the radiation which these motions excite, and their close relation to chemical change. His ideas (Query 17 seq?), of essentially modern type, involved a medium infinitely more rare than air and of infinitely stronger elasticity — aether is his own name for it — amidst the waves of which the atoms of matter and the corpuscles which he took to constitute light were agitated like logs in a sea ; of such a medium the elastic pressure, weaker on the adjacent sides of bodies, might, as he thought, in some way represent gravitational attraction, while its dead resistance to planets moving through it would be, owing to its small mass, quite negligible. At the end of a prolonged physico-chemical dis- cussion he sums up his atomic view of the constitution of matter {loc. cit., p. 375) in archaic terms with deep modern significance, that have often been quoted : "All these things being consider'd, it seems probable to me that God in the Beginning form'd Matter in solid, massy, hard, * "Opticks," ed. (3), pp. 313—382. Manchester Memoirs, Vol. Hi. (1908), No. 10. 7 impenetrable, moveable Particles, of such Sizes and Figures, and with such other Properties, and in such Proportion to Space, as more conduced to the End for which he form'd them ; and that these primitive Particles being Solids, are incomparably- harder than any porous Bodies compounded of them ; even so very hard as never to wear or break in pieces : No ordinary power being able to divide what God himself made one in the first Creation, While the Particles continue entire, they may compose Bodies of one and the same Nature and Texture in all Ages : But should they wear away, or break in pieces, the Nature of Things depending on them would be changed. Water and Earth composed of old worn Particles and Fragments of Particles, would not be of the same Nature and Texture now, with Water and Earth composed of entire Particles in the Beginning. And therefore that Nature may be lasting, the Changes of corporeal Things are to be placed only in the various Separations and new Associations and Motions of these permanent Particles : compound Bodies being apt to break, not in the midst of solid Particles, but where those particles are laid together and only touch in a few Points. " It seems to me farther, that these Particles have not only a Vis inertiae, accompanied with such passive Laws of Motion as naturally result from that Force, but also that they are moved by certain active Principles [Energies], such as that of Gravity, and that which causes Fermentation, and the Cohesion of Bodies. These Principles I consider not as occult Qualities, supposed to result from the specifick Forms of Things, but as general Laws of Nature, by which the Things themselves are form'd ; their Truth appearing to us by Phaenomena, though their Causes be not yet discover'd. For these are manifest Qualities, and their Causes only are occult " This survey carries us about as near as purely physical speculation, based on the broad simple principles of universal dynamics that Newton was the first definitely to codify, could approach towards an atomic theory. And it is a considerable advance. The uninstructed tendency, judging from one's own early recollection, is to assume 8 LarmOR, Physical Aspect of the Atomic Theory. that the apparently continuous substances around us are divisible without limit, and afterwards to wonder what sort of evidence it is that has suggested the contrary conclusion. Such evidence must have an essentially chemical flavour : its gist has been strikingly expressed by Newton in the argument of which the conclusion has been quoted. It is true that the mathematical physicists of the beginning of the nineteenth century were accustomed to conduct their investigations in terms of atoms or particles of bodies : but for their purposes, these terms were hardly much more than the embodiment of the fact that exact reasoning requires numerical expression, and therefore, the mathematical resolution of the media with which it is concerned into infinitesimal geometrical parts.* On a rather higher plane must however be placed the (subsequent) electric atoms of W. Weber, which may be held to have been somewhat unduly discredited by the destructive criticism of Helmholtz. The Daltonian Atoms. Early in the nineteenth century the time had come for the translation of these dim physical perceptions into secure experimental knowledge. Perhaps the new feature *An exception must be made at any rate in the case of Young, as will appear in connexion with optical dispersion, and, as Lord Rayleigh has remarked, in connexion with capillarity. In a letter to Arago (Jan. 12, i8i7)> he reports : — " I have been reconsidering the theory of capillary attraction and have at last fully satisfied myself with respect to the fundamental demonstration of the general law of superficial contraction, which I have deduced in a manner at once simple and conclusive from the action of a cohesive force extending to a considerable number of particles within -a given invisible distance. This solution has very unexpectedly led me to form an estimate, something more than merely conjectural, though not fully demonstrative, of the magnitude of the ultimate atoms of bodies ; in water for instance, about " io~*cm. in diameter [modern estimates being nearer lO-^cm.]. Young's "Works," ed. Peacock, vol. i., p. 382 ; also article *' Cohesion," loc. cit. p. 462. . Manchester Memoirs, Vol. Hi. (1908), No. 10. 9 developed by Dalton is at bottom describable as the principle of the essential homogeneity of each pure substance, that it is composed of molecules of only one type, absolutely alike. Once it is postulated that only one kind of aggregation into molecules occurs, e.g., that in water there is only one way in which the hydrogen attaches itself to the oxygen, the laws of definite and multiple proportions are self-evident. The only way to ascertain the truth of this hypothesis was to test the consequences experimentally. In the hands of Lavoisier it had become clear that in chemical transformation mass does not to a sensible extent ever disappear or re-appear, that chemical operations are not attended by dissipation or destruction of matter. In the hands of Dalton it became clear that each type of substance is characterized by its own specific type of aggregation of constituent atoms, by its own molecule. At that time neither principle could have stood out in the full light in which we are accustomed to view it now. Physical ideas had retrograded since Newton's day. The heat which to his view seemed so obviously to be vibratory motion, due to the clash of atoms under their specific energies, had come to be regarded since Stahl, aided perhaps by a misreading of Black's doctrine of specific and latent heat, as a substance combined in various proportions with different bodies, on the idea that it is only something material that could be conserved. And, moreover, as in all fundamental advances, the result attained was not so much the vindication of any inflexible experimental fact, as the introduction of an abstract guiding principle into the Science, fortified of course by experimental support. For it is still a legitimate aim of experiment to try whether any detectable change, either in mass or in gravity, is produced by that lo LarmoR, Physical Aspect of the Atomic Theory. re-aggregation of atoms to form new molecules, which constitutes chemical reaction. Some day the ascertained fact, that such influence of the close partial superposition of the fields of energy of the adjacent atoms in the mole- cule is at any rate almost infinitesimally small, may play a part in the elucidation of the mode of operation of gravitation. The essentially cognate fact, that no intervening obstacle can modify sensibly the gravitation of two masses, has already drawn us towards the position that the nuclei of the fields of stress, which constitute the physical aspect of atomic forces, are excessively small compared with the distances apart of these interacting nuclei in the fields of activity which are the atoms. In the same way the Daltonian principle, of a definite molecule for each substance, now stands in intimate connexion with the Berthollet idea of statistical or mobile equilibrium, which requires that in the active interchange that is always going on among ultimate constituents of a substance, all the possible types of molecules which have any degree of stability must be present in some amount,, though in most cases practically infinitesimal. It has also to take cognizance of fundamental considerations of a biological character, which will be referred to later. While theory is aimless and impotent without experimental check, experiment is dead without some theory, passing beyond the limits of ascertained know- ledge, to control it. Here as in all parts of natural knowledge, the immediate presumption is strongly in favour of the simplest hypothesis ; the main support, the unfailing clue, of physical science is the principle that, nature being a rational cosmos, phenomena are related on the whole in the manner that reason would anticipate. Radiation. In sketching the progress of the purely physical 'Manchester Memoirs, Vol. Hi. (1908), No. 10. ii notion of atomic structure there is also another fun- damental order of ideas, arising from the phenomena of radiation, which must be included — the conception of an atom or molecule as a vibrating system of some sort^ complete in itself and reacting by resonance with such waves of radiation as have periodic times adjacent to the periods of its own free vibration. In the famous memoir " On the Theory of Light and Colours " read by Thomas Young before the Royal Society on November 12th, 1801, which, in the form of a mass of brief and pregnant suggestions, lays the foundation of modern physical optics, the view of the refraction of light, as due to the reaction of natural free vibrations of the constituent parts of the refracting medium, had already been advanced. The passage perhaps demands quotation.* After giving a correct apergii of the mechanism of total reflection, as involving and being supported by surface waves in the rarer medium, he proceeds as follows : — ^'■Proposition VII. If equidistant undulations be sup- posed to pass through a medium, of which the parts are susceptible of permanent vibrations somewhat slower than the undulations, their velocity will be somewhat lessened by this vibratory tendency ; and, in the same medium, the more, as the undulations are more frequent. " For as often as the state of the undulation requires a change in the actual motion of the particle which transmits it, that change will be retarded by the propensity of the particle to continue its motion somewhat longer ; and this retardation will be more frequent and more considerable as the diiference between the periods of the undulation and of the natural vibration is greater." It is hardly possible to extract definite meaning from this cryptic explanation : indeed, the dynamics of a com- . * " Lectures on Nat. Phil.," quarto edition, vol., ii., p. 623. 12 Larmor, Physical Aspect of the Atomic Theory. pound vibrating system is nowhere treated by Young ; but, at any rate, he would have been quite prepared to predict the modern phenomena of anomalous optical dispersion as arising from the sympathetic vibrations of the mole- cules of the material medium. Later (1817), on again taking up the subject of Physical Optics, in his Article in the Encyclopcsdia Britannica on *' Chromatics," he seems to have been dominated by the new puzzles connected with his principle of polarization due to transverse vibra- tion, and this mode of explaining dispersion is dropped. What are these parts of bodies — solid, liquid, or gaseous — which are thus taken to be susceptible of per- manent vibrations of their own? At any rate, the hypothesis implies a thoroughly discrete structure of matter. And it is perhaps remarkable that Young was not tempted to ascribe the slowing of the period belonging to a given wave length to the mere loading of the aether by inert structureless particles of matter, in the manner of the explanation of dispersion which Cauchy and Poisson afterwards imposed on optics ; he went to the root of the question, in the Newtonian manner (as he remarks in the appended Corollary and Scholium), by ascribing to these particles free periods of intrinsic vibration, and therefore definite and identical structures. Nothing further is heard of this point of view until the origin of the lines of the spectrum, and the mechanism of the production of the dark Fraunhofer lines, were discussed between Stokes and W. Thomson in 1854.* In i860, in introducing the practical discovery of spectrum analysis by Kirchhoff and Bunsen to the notice of the British public, Stokes based his dynamical explanation of selective absorption of radiation on the simple remark that, when the waves passing through the medium are * G. G. Stokes, " Math, and Phys. Papers," vol. 4, 1904, appendix Manchester Memoirs, Vol.lii.{igo?)),No.\Q. 13 closely attuned to it, so as to induce strong sympathetic vibration in the parts of the medium which they traverse, the radiant energy emitted by these active vibrators must be supplied from that of the exciting train of waves. But it appears that, in following out this chain of ideas on the nature of optical absorption, it had not occurred to either Stokes or Thomson to consider the reaction exerted by the vibrating absorber on the train of waves ; and the elucidation of the dispersion of colours in light as due to the induced vibrations of the molecules, which had naturally presented itself to Young at the beginning of the century, remained to be enforced by Maxwell, Rayleigh,* Ketteler, and especially Sellmeier, having been as it seems definitely perceived and sought for experimentally, in the form of anomalous dispersion near a region of absorption, by the latter, as early as 1866. As the matter presented itself in luminous brevity to Lord Rayleigh, the medium is capable of free standing vibrations after the manner of a plucked string, executed in a periodic time which is determined for each type of vibration, i.e., wave-length, by its elasticity and inertia alone, provided it contains no independent internal vibrators that could be excited cumulatively by this motion : but where it contains structures that can set themselves vibrating in sympathy, the circumstances are analogous to those of an oscillating string on which light free pendulums with periods of their own, near those under consideration, are hung : the regular swing of the system now takes place in a modified time, and the velocity of propagation, determined by the ratio of wave- * See an early paper by Lord Rayleigh, " Scientific Papers," pp. 14X — 6 (1872) — prior to the publication of Sellmeier's demonstration, but, as he now thinks, possibly written with recollections of Maxwell's ideas — in which the practical inadequacy of mere differences of passive optical density is insisted on. 14 Larmor, Physical Aspect of the Atoviic Theory. length to periodic time, must be altered, precisely in the manner that optical observation confirms. The atomic constitution of matter is thus involved, in a highly refined manner, in the group of phenomena connected with the chromatic dispersion and absorption of radiation. But to gain conditions of ideal simplicity, we must attend to the case of gases where each molecule is isolated and free from encounter with others during the period required for thousands of its optical vibrations, where in fact it can be treated as vibrating free. The sympathetic vibration and resulting absorption along the spectrum, in liquid and solid bodies, are influenced in complex ways by the transient combinations of the molecules into groups : though the general relations elucidated by experiment between specific mean refraction and chemical structure suggest something often approximating to mere simple aggregation. The Function of Conceptual Models. In the case of every successful scientific theory, the time must come when its first easy triumphs become exhausted, and what prominently confront the investi- gator are its outstanding defects and difficulties. When this stage arrives, one way of saving appearances is to purify the theory by banishing all terms which have an illustrative or analogical connotation, expressing its verified relations alone by new words which represent simply general types of mathematical quantity — vectors, scalars, rotors, etc. When such a state of crystallisation has fully set in, further progress in general views is hardly to be hoped for — the sources of invention are dried. up — though details in such a restricted abstract scheme will continue to be filled in, while new phenomena will probably suggest arbitrary unexplained additions to its content. -Manchester Memoirs^ Vol Hi. (1908), No. 10. 15 Even in chemical philosophy it has at times been a matter of concern that, for example, water is described as containing- oxygen and hydrogen, whereas really it retains precisely none of the properties of either of these sub- stances. Though it be admitted that it is constituted of molecules, yet the molecule of water is something different from its constituents ; and it is held to be a crude or even unwarranted image that suggests that in it an oxygen atom and two hydrogen atoms lie alongside either at rest or in orbital motions. Criticism like this attaches to all inferences that cannot be tested by direct sensual perception. What we can know in any direct manner about chemical combination is expressed merely in the laws of definite and multiple proportions. Such a revision of the mode of expression of our knowledge as this criticism sug- gests may be useful occasionally as a stock-taking ; but the misconceptions which it guards against are seldom real, and indeed it makes little, if any, permanent appeal on the physical side of the science. Here almost everything has been constructed on the basis of dynamical ideas, — those fundamental Newtonian ideas of force and inertia which constitute the simplest formal scheme that admits of permanence of free motions, — applied to conceptual models ; such a theoretical representation is never perfect or complete, but it is vivid and illuminating, and histori- cally it has been progressive ; to give it up would be to replace a growing system by a collection of fragments of knowledge. The physicist in his own range is never likely to forget that any simple piece of matter is a vast interlacing, interdependent complex, which he can never hope completely to disentangle or resolve : he is certain that matter is of grained structure, but to him the grains are very far from being mutually isolated things, — each of them is actively influenced by all the others around it. 1 6 Larmor, Physical Aspect of the Atomic Theoiy. Yet he has no alternative but to hold that each ultimate grain is itself a self-existing cosmos, of complexity probably beyond any complete analysis on our part, which may indeed to appearance merge itself in combina- tion with another atom or molecule, but is always recover- able unaltered, — that there is no degradation of matter. He holds probably that it is necessary to believe that in the same pure substance the molecules are all exactly alike, or, at any rate, that they are as nearly alike as individuals of a very sharply defined species in the organic world ; though he knows no natural reason which would compel them to be so constituted, except in so far as they may represent the limited number of types of dynamical structures that can be built up from simpler identical primordial elements. It is vastly more suggestive to accept this wonderful inference, which constitutes the Daltonian theory, as our working hypothesis, than to try to refrain altogether from analogical reasoning about unseen mole- cules : moreover, this procedure is almost imposed a priori by the general principle already alluded to, that the simplest theory is probably the most fruitful representa- tion of reality. There is one branch of actual observational knowledge in which this identity of the molecules of a substance asserts itself with special strength : if the molecular theory had not been introduced on the evidence of the laws of definite and multiple proportions in chemical compounds, it must have demanded recognition as a result of a study of the crystalline structure of bodies. We call to mind that correspondences are now coming to light by which it is becoming possible to reason regarding the type of the molecule, and the geometrical grouping of its constituent atoms, from measurement of the crystalline aggregate : in such cases the single Manchester Memoirs, Vol. lit. (1908), No. 10 17 molecule would itself be the ultimate formative crystalline element. Where an atom has a higher valency, it must, according to any formula of spacial chemical constitution, aggregate more atoms around it and in touch with, it in the molecule : it must, on that account alone, itself occupy or exist in a larger central space. In this way greater atomic volume would be in general a result of greater valency, while the atomic volume will always be nearly the same in similar surroundings : the very striking recent investigations to ascertain how far the structure of the crystal is determined by the arrangement of the atoms in its molecule on the basis that equi-valent atoms require about the same atomic volume, are known to all of us here.* The contrast has recently been sketched by Professor Voigt in eloquent terms between this domain of the properties of crystals, where all is definite, orderly arrange- ment, and that of liquids and gases where physical properties are merely average values which belong in the statistical sense to crowds of jostling molecules. But even here of course the regularity is limited ; the molecules become confined more or less securely in definite positions by the mutual forces of cohesion, but not so firmly as to prevent them from taking part in the conduction of heat and other modes of equalisation or dissipation of energy ; the very bonds of cohesion are themselves functions of the temperature. The tendency of most physicists would still probably be to take comfort from a remark of Helmholtz, published in one of his letters, to the effect that organic chemistry progresses steadily and surely, but in a manner which, from the physical standpoint, appears not to be describable as quite rational. Yet as time goes on it * Barlow and Pope : Cf. Trans. Chem. Soc, 1906. 1 8 Larmor, Physical Aspect of the Atomic Theo}y. becomes increasingly difficult to resist the direct evidence for the simple view that, in many cases, chemical com- bination is not so much a fusion or intermingling of the combining atomic structures, as rather an arrangement of them alongside each other under steady cohesive affinity, the properties of each being somewhat modified, though not essentially, by the attachment of the others ; and that the space formulae of chemistry have therefore more than analogical significance. The many instances, thermal capacity, refractive index, etc., in which the physical properties of the compound molecule can be calculated additively with tolerable approximation from those of its constituent atoms, are difficult to explain otherwise. The crystallographic evidence has already been referred to. The Spectrum. Yet the spectrum, which the physicist is accustomed to regard as the most complete (though largely undeciphered) index of the structure of the molecule, is totally different, at any rate in the simpler combinations as compared with single atoms, unlimited groups of lines (forming bands) taking the place for the molecule of the single lines of atomic spectra. It may be permissible to believe — it is now in fact widely accepted — that no stimulation of an atom, less violent than complete disruption of some molecule in which it exists, can suffice to excite sensibly its atomic line spectrum. But there seems to be more corre- spondence between the absorption spectra of complex molecules and those of the molecules or radicles of which they are built up. The difference is fundamental between the firm, almost unalterable structures which are the atoms, and the molecules, considered as intimate definite aggre- gations of atoms capable of definite disruption ; it ought Manchester Memoirs, Vol. Hi. (1908), iV^. 10. 19 perhaps to involve the corollary that sensible internal vibratory disturbance in the former is far more difficult to excite than in the latter. In the case of molecules of easily condensable gases, between which, therefore, strong mutual forces come into play, there seems to be evidence that the natural thermal collisions alone can excite selective radiation, as indicated by the appearance of band spectra under conditions of high temperature without chemical or electric action : in the case of atomic line spectra the negative results of Fringsheim and other observers seem consonant with what was to be expected. Line spectra are of very great luminous intensity compared with any natural continuous spectrum on which they can be superposed, unless the temperature of the latter is extremely high, and therefore the molecular collisions very violent. This seems to afford sufficient reason why they cannot be considered as in any kind of energy equili- brium with the surrounding continuous radiations. An adequate interpretation of the master clue to dynamical molecular structure afforded by the spectrum is still lacking. The researches of Liveing and Dewar, Balmer, Rydberg, Kayser and Runge, Rayleigh, Schuster, and others, have led to the division of the simpler line spectra into correlated series of lines, with the successive vibration frequencies in each series, after the first one or two, determined by simple approxi- mate formulas, obviously the asymptotic forms of more complex exact relations which remain to be dis- covered ; but very little progress has yet been made towards the dynamical interpretation of this ordered system. The radiations from electrons involve their accelerations, while those from ordinary material vibra- tors, as, for example, in the case of sound waves, depend only on velocities ; thus, as Lord Rayleigh has remarked. 20 Larmor, Physical Aspect of the Atomic Theory. it is hardly surprising that the law connecting the over- tones (so to speak) with the fundamental in each spectral series is of a type that is not met with in ordinary dynamics. A probably easier problem, as yet unravelled, is the mode of genesis of banded spectra ; here the law connecting the frequencies of the series of lines which constitute a band is of type not unfamiliar,* but the known conditions in which these relations occur seem rather complex for an ordinary molecule. The facts that increased density of the surrounding medium does not shift the bands, and that the Zeeman magnetic effect is absent in bands, are very pertinent to the problem : it has been thought that these facts are somehow correlated : it may well be that the former indicates close concentra- tion of the steady aethereal vibration into the interatomic spaces in the molecule.f But though the problem of the dynamics of the spectrum has not hitherto yielded much under the accumulation of knowledge, the primal property of the spectrum as an analytical agent remains unimpaired. It is still true that the occurrence of a definite line marks the presence of a definite substance. With variation of the conditions of excitation that substance may or may not emit the line in question : but wherever the line is seen the inference backward is still valid, though high dispersion may of course be requisite to distinguish it from closely adjacent lines. The inference as to the presence of a substance is easy ; but it would be far more difficult to establish its absence. Among the remarkable results of recent research in this field are those of R. W. Wood on the fluorescent spectrum of sodium vapour, and the conditions of its * Cf. "Ency. Brit.," ed. ix. supplement (1900), Art. 'Radiation.' t Cf. Astrophyskal Journal, 1907, p. 120. Manchester Memoirs, Vol. Hi. (1908), iV which also brings to a focus many of the peculiarities of gaseous reaction. In the same paper it was announced that the bimolecular reaction of CO with N„0 is not excited by the electric spark when the gases are well dried, though the mixture becomes explosive on the addition of water vapour. The argument in the text need not imply that every bimolecular reaction proceeds spontaneously ; in such a case as the oiie quoted the ordinary explanation is appropriate, which regards a catalyst as opening a path of transformation around an obstructing ridge on the surface of avail- able energy, such as would present a barrier to direct combination. As in electric phenomena, so in chemical change, the apparent anomalies of reaction in pure gases seem destined to provide the clue towards deeper insight, as, in fact. Lord Rayleigh pointed out long ago. 30 Larmor, Physical Aspect of the Atomic Theory. reactions where more than two molecules are concerned, such as 2H2 + O2 and 2CO + O2 the chance of them all being in contiguity at the same instant is extremely small compared with that for two, and the reaction can therefore only proceed very slowly, unless it proceeds by intermediate binary reactions such as the formation of H2O2 in the first case or reaction with contained water vapour in the second case. This superior velocity of binary combination has possibly a bearing on the specific catalytic action of traces of certain foreign vapours in facilitating explosive combination, as determined by Dixon." I see no reason to abandon the conclusion thus ex- pressed, t is quite sound to reason, in the statistical man- ner introduced by Guldberg and Waage, that the relative number of direct diad combinations between molecules of types A and B is k^j^.nj^.ni^, where the factors of type n are the respective numbers of these molecules, and that the number of direct triad combinations between types A, B and C is k ^Ji(,. Hj^.u . u^ ; but it would appear that the coefficient ^^ec of the latter combination must be almost infinitesimally small compared with Z'^^. Thus if we imagine the scale of magnitude of a gas at a pressure of one atmosphere to be magnified so that the diameter of each moving molecule becomes about one inch, there will be in the model roughly about one molecule in each cubic foot, and a molecule will have to travel about a hundred feet before it encounters another one. Such binary encounters will thus happen with some frequency, and from some of them combination may ensue. But the chance of three molecules coming together simultaneously is negligible : the only way in which a trimolecular combination can arise is by one of the molecules attaching to itself another, in a manner perhaps relatively transient, and this pair going off together to meet the third, each acting so to speak as a Manchester Memoirs, Vol. Hi. (1908), No. 10. 31 carrier for the one united with it. Without some such intermediate transient stage of combination a dissociation of a complex into three molecules must proceed to an end, for the chance of an equilibrium through recombination would be negligible. Where an equilibrium is found to become established, either the reaction must occur in binary stages, or else it must take place in contact with solid or liquid boundaries where the molecules form a denser layer in which each is alwaj^s in relation with others. This consideration reinforces the importance of the study of reaction in pure gases, as a means of disentangling the intermediate stages of chemical combination and the durations of the products formed in them. The fundamental importance of this kind of knowledge for the adequate interpretation of banded spectra has already been alluded to. It appears, indeed, to be commonly recognised that direct trimolecu- lar combinations occur seldom : the inference from the present line of argument is that in gaseous reactions they do not occur at all. Recently I have learned that Mendeleef had always maintained that gaseous reaction occurs in monomolecular or bimolecular stages in all cases : there seems to be strong presumption in favour of such a view. It would require the instincts of a chemist to venture on any attempt to apply this principle to special cases, to discuss why, for example, the presence of a foreign sub- stance sometimes promotes the occurrence of the necessary intermediate binary reaction, and in other cases pre- sumably destroys its product, and so inhibits the final transformation. The recent results obtained by Bone and Edmunds for the thermal dissociation of HoO agree with the conclusions drawn in 1884 by Dixon with regard to the explosion of a mixture of CO and O^, in assigning 32 Larmor, Physical Aspect of tJie Atomic Theory. ' the presence of hydrogen free or combined as a potent stimulus to ternary reaction.* lojiisation and Solution : Available Energy and BertJielofs rule. At first sight it might appear that the principles of statistical equilibrium in dilute systems would afford a criterion as to the intimate process of dissociation, whether into ions or molecules. Thus, to fix the ideas, the two reactions, HC1 = H + C1 and 2HC1 = H2 + Cl would come to different equilibria, of the types n = k .n^n^ and ir = k'.n\n\. But in reality the subsequent aggre- gation of H and H into H., itself involves an equilibrium ni= J{Kn\), so that the discrimination is not possible on these considerations alone. Nor is it ever possible in this way on the thermodynamic theory, which can be seen (c/. Appendix) to be consistent with separate independent equilibria as regards every type of reaction that is formally possible in the system. The process of ionisation in a liquid solvent is obviously very different from ordinary gaseous dissociation. The view that some such special type of dissociation is required in order to form a coherent mental picture of Faraday's electrolytic results, must really in strict logic go back to Clausius' ideas of about fifty years ago. It is true that he did not venture to suggest more than extremely slight ionic dissociation. But once the mere possibility is granted, there is no ultimate escape from the permanent ionic separation of Arrhenius : for it is only a question of making the solution more and more dilute in order to diminish indefinitely the chance of * I have ventured to add an abstract discussion on the formal possibilities that are open, which was drawn up about a year ago, as an Appendix. Manchester Memoirs, Vol. Hi. (1908) No. 10- 33 any two ions ever meeting again to unite, as compared with the unaltered chance of any remaining whole molecules becoming divided into ions. Complete ionis- ation must ultimately arrive ; and there is only the question remaining over as to the degree of dilution at which it is practically attained. It will be observed that we are in this argument applying the principles of mobile equilibrium to the ionisation of the dissolved substance. Here an appeal to experiment becomes feasible. It was by Ostwald that this test of Arrhenius' view was first applied. As is well known, he found that for acids and salts that are but slightly ionised, ^.^., acetic acid, the mathematical relation expressive of equilibrium of simple dissociation is satisfied ; but for highly ionised substances it is widely departed from. The verification in the former case appears to be sufficient by itself to confirm the general point of view. For it seems natural to suppose that high ionisation indicates the presence of some type of direct affinity with the solvent, which is too powerful to be altogether omitted from the equation which expresses the ultimate equilibrium. How such an influence should be included is one of the main unsolved problems in this subject. At higher concentrations either the tendency to re-combination of the ions is resisted, or else the tendency to ionisation of the molecules is promoted. Thus if increased ionisation were a result of collision of molecules with the existing ions, in analogy with known effects of collision of (rapidly moving) ions with the molecules of gases in promoting further ionisation, the equation of equilibrium would be altered from n^ = kn to n^ = k7i-\-k'?tn^, in which k'fk would be sensible only for easily ionisable substances (cf. Appendix). The solution of this problem, if there is any simple colligatory 34 Larmor, Physical Aspect of the Atomic Theory. principle, must, however, be a matter of experimental scrutiny. The acceptance of the idea of ionic dissociation by solution has been opposed by scruples of a more funda- mental kind, not altogether unlike the difficulties once attaching to the Berthelot doctrine that the extent to which a reaction proceeds depends on the relative amounts of reacting substance. It is a fundamental postulate that a molecule is a self-existent aggregate, whose intrinsic binding affinities are independent of temperature : as we have seen, one of the main a posteriori reasons for this conclusion is that each (sharp) line of the spectrum is characteristic of the molecule, alterable in position only very slightly, or not at all, by any change of physical conditions. And this view agrees with the kinetic theory which connects temperature with the average translatory (and concomitant rotatory) motions of the molecules in space, and sometimes with partial dissociation, but not with any intrinsic change in structure in the molecules that are present. Thus the bonds of atomic affinity which have to be over- come, say in the ordinary non-ionic dissociation of a gas, are the same at high temperatures as at low. But occasion- ally a collision with another molecule may be well-directed towards breaking these affinities, like the sharp impact of a mason's trowel on a brick or tile, and as a rule it will be the more effective the higher the temperature. The verifi- cation of the theoretical law of equilibrium, in ordinary gaseous dissociation, enables us to assert that strong affinities are in fact occasionally thus shattered ; that high affinity is to be measured not by entire absence of disso- ciation but by its relative rarity, though the products of disruption can be accumulated when the opportunities for recombination are removed. The dissociation into ions Manchester Memoirs, Vol 7n. (igoS), No. 10. 35 in a solvent is perhaps a more fundamental change than the ordinary dissociation of a gas : yet the ions may accumulate notwithstanding, for the obstacles to recombi- nation presented by the dense molecular aggregation of the liquid in which they are entangled are also enormous in comparison with any that are present in the gas. Thus the circumstance that self-ionisation is hardly detectable in a gas is not conclusive evidence that it never occurs without the assistance of a liquid solvent medium. It seems worth while 16 follow up these relations somewhat further in the light of Faraday's conclusion, so emphatically enforced by Helmholtz in i88i, that the strongest forces of chemical affinity are of electric type. It would almost seem as if we must adopt the view that the active atom in ordinary chemical change is the ion, with its large intrinsic electric charge as an essential feature. No permanent state such as we associate with a simple dense material substance can be reached until these enormously active positive and negative bodies have become paired ; until, in fact, their domains of activity, in place of being the widely ramifying fields of force of free ions, are changed to the more concentrated and individualised fields of molecules,* in which the lines of force instead of spreading out far into space simply pass across in more or less curved lines from one ion to its adjacent conjugate. No substance could exist completely ionised in free space for a moment, nor with any considerable excess of ions of one sign : ionisation is, however, continually occurring in substances to a small extent, spontaneously and so to speak by accident, i.e., in a manner not con- * In the molecular groups of solvent media, which have abnormally high dielectric capacities, the two conjugate ionic poles are so far apart that these groups may be held to occupy a position intermediate between ordinary molecules and active ions. Cf. p. 37. 36 Larmor, Physical Aspect of the Atomic Theory. trollable, the duration of separate existence of the ions depending on the obstacles to their finding new partners In the case of gases in which the formation of ions is stimulated by electric shock (Rontgen rays, etc.), know- ledge is now highly developed (J. J. Thomson, Townsend etc.) regarding their rate of formation, and its equilibrium with recombination or with their extraction from the region by an electric field : the processes in solutions are much more rapid, and only resulting equilibria can be directly investigated. The operations of inorganic chem- istry consist largely in presenting to these ions of solutions the possibility of taking on new partners, either by simple admixture, or by pulling them away into a new environ- ment by electric agency. The energy required for the guidance of chemical processes is expended in this latter way, perhaps none of it goes (except very indirectly through thermal interchange) to the pulling asunder of the ions in the atom ; that separation takes place spor- adically, with purely local adjustment of energy, to an extent dependent, however, on the environment and in this way modifiable. Any intense motional disturbance liberated in such ionisation lapses into mere thermal energy. But by means of guiding control (constraints in bulk) little of i,t may be left to this fate — e.g. in the Daniell voltaic cell, as Lord Kelvin discovered half a century ago. Here again we recall the emphasis placed by Helmholtz, in 1 88 1, on the inference that in a voltaic cell there is but slight expenditure of energy in getting the current across the solution, merely, in fact, the Joulean heat, while the large amounts of energy which become available or stored have their origin at the electrodes, in that process (often, as will be seen, nearly statical) of passing over the Fara- day unitary electric charge from atom to atom, which is, Manchester Memoirs, Vol. hi. (1908), No. 10. 37 therefore, the essence of the change in the state of chemical combination. The source of the energy required for the natural degree of ionisation which occurs when, say, K.HO is dissolved in water, has been a standing problem in this department. The current mode of explanation seems so far sound, that when a dilute base is neutralised by an acid, say K.HO by H.Cl, the resulting heat is derived from the free ions H and HO clashing together at high speed generated by their strong electric attraction, as H^O does not exist sensibly ionised — that therefore the heat evolved is about the same per chemical equivalent in all such cases. But when K.HO is added to water, whence comes the supply of energy demanded for the pulling apart of the K and the HO, into separated ions, against their mutual attraction ? The concomitant absorption of heat is far too slight to account for it* We are tempted to conclude that internal potential energy is released owing to the ions falling into relations of closer affinity with the solvent, and that the process is nearly a self-contained interchange of energy, reversible as regards each molecule separately, being a steady static drawing apart of the ions unaccompanied by the generation of violent subsidiary electronic motions whose energy would escape into the general store of heat. The fact above alluded to, that in voltaic batteries so large a proportion of the chemical energy is usually mechanically available, also seems to point this way ; it shows, too, that the fundamental interchanges of electrons at the electrodes, which are the sources of the transformation of energy, are intrinsically of the same not merely reversible but almost * Cf. G. F. FitzGerald : Helmholtz Memorial Lecture, Trans. Chem, Soc, 1896: "Scientific Writings," p. 363 seq., also p. 521. 38 'Laruor, Physical Aspect of the Atojnic Theory. static type, accompanied by but little energy of intense agitation such as would be partially dissipated into the surroundings. It may thus be the close quarters at which these operations are developed, in the liquid environment, that limit both the occurrence and the diffusion of irregular intense disturbance such as would pass away into sensible heat. In ordinary dissociation of the nearly free molecules of gases, accompanied by comparatively large changes of volume or pressure, or in the cognate phenomena involving osmotic expansion of dilute solutions already formed, a relatively greater degradation of energy is involved, and is indicated by the greater variation of the equilibrium on change of the temperature. The history of this problem may be recalled. When Lord Kelvin opened up the subject of availability of chemical energy in 185 1, he found by experiment that in a Daniell cell nearly the whole of the energy of chemical combination was available for mechanical work. Later Gibbs in 1878 and Helmholtz in 1882 pointed out that the change of electromotive force with temperature gave a measure of the proportion of the energy that is not thus available: and the accumulating cases of discrepancy with Kelvin's principle thus became rational. Now the problem is rather why the unavailable part proves to be often so slight, as compared with other chemical processes more thermal in character. Not merely can the opera- tions be conducted in a nearly reversible manner, so that all the available energy is utilized, but in addition nearly all the energy of the chemical change is often actually available so that there is but slight evolution of heat where it occurs. It will be remembered that Professor Nernst devoted his recent Silliman Lectures to this subject. " To enable us to proceed it is necessary to find the conditions under which the principle of Berthelot comes Manchester ATemoirSy Vo/. /zi. (igoS), No. 1{^. 39 nearest to expressing the true relation between [available] chemical energy and heat, or, what amounts to the same, between the magnitudes A and Q. In this direction we can show that in reactions between solids, liquids, or concentrated solutions, the values of A and Q approach each other very closely, while on the other hand in dilute solutions or with gases we actually find large differences between the two quantities ;..."* The case of galvanic cells operating even by dilute solutions is included in the generalization for the reason given above. Obviously also on the present view the unavailable part of the energy should become steadily less at lower temperatures, as Nernst concludes. The principle of Gibbs, that the fraction of the energy of chemical combination that is unavailable is equal to the ratio of the actual temperature of reaction to the temperature of dissociation, pro- vided correction can be made for work of expansion and heat on change of state, etc., is seldom effective on account of this latter complication. The Faraday unitary charges have now a specific name, the electrons. Their unchanging magnitudes were strong presumption from the first of their intrinsic atomic existence : the Zeeman-Lorentz effect has almost exhibited them to us in action in the molecule, as the agents of radiation through their combined vibratory motions, in the now familiar manner foreshadowed by the Maxwell- Hertz theory of radiation. But the most far-reaching of recent discoveries has been that not merely can they pass at close quarters from molecule to molecule in some hitherto inscrutable way, according to the Faraday law, and also reveal their vibrations inside the molecule through its spectrum and its magnetic modifications, * Nernst, /oc. cit. "Applications of Thermodynamics to Chemistry," 1907, p. 43, seq., where extensive examples are given. 40 Larmor, Physical Aspect of the Atomic Theory. but that they can be drawn out into the open by electric shock, and securely manipulated (J. J. Thomson, Lenard, etc.) as atoms of pure disembodied electricity in those cathode streams across highly rarefied gases which Sir W. Crookes long ago insisted on calling a fourth state of matter. In the electrolysis of an acid we are to imagine the negatively charged massive hydrogen ions, which happen sporadically to be free in the solution, as being slowly drawn towards the negative electrode by the electric field pervading the medium, as accumulating there with pro- duction of polarisation reacting against this impressed electric field, until they are so crowded together by the constraint that some kind of instability arises, whereby one of them takes over, but without violent disturbance such as could diffuse away, two positive unitary charges from the electrode. Surely these charges must in ultimate analysis be positive electrons, or else the power of losing negative ones must be unlimited. At any rate, in virtue of them, the ion can associate with another and become released as a free self-contained molecule of hydrogen, a very different thing from the mutually constrained ions that gave rise to it, — the energy required for the electro- lysis being expended mainly, as Helmholtz insisted, and, as we have seen, usually without much necessary waste, in this requisition of the two positive charges. The relevance of the mode of operation of the Grove gas battery will here occur to mind ; the finely divided or porous platinum surface promotes ionisation of the gas alongside it through the opportunities arising from intimate contact in confined spaces {cf. p. 37), and so manages to utilize much of the available energy of gaseous combination, which in gases is very different from the heat of combination on account of the change occurring Manchester Memoirs, Vol. Hi. (1908), No. 10- 41 in the energy of expansion. Fortunately for exact knowledge, the principles of thermodynamics give in all such cases the means of estimating the final result, without requiring hypothesis as to the nature of the process that is involved, provided only it be reversible ; in dilute systems the argument can be ex- pressed in terms of the available energies, or thermo- dynamic potentials, of the constituents, interpretable in the simpler cases by partial osmotic pressures — in exten- sion of which the idea of solution pressure of an ion can be employed as a graphic mode of expression, without implying that the processes involved can be placed in effective analogy with those of evaporation or solution. The very remarkable quantitative connexion of the electric potential gradient between solutions with the diffusions of their ions, established by Nernst, must ever remain one of the solid foundations in this subject. The modern expression of Helmholtz's provisional generalisation, that chemical affinity arises from intrinsic attraction of the different kinds of matter for electricity, may roughly be that every active atom is an ion, and that saturated inert molecules are welded into unity by each constituent atom keeping hold, through the aethereal agency of electric attraction, of the (perhaps inter- penetrating) electrons belonging to the other. The electrical view provides a reason for the ordinary saturated inactive molecule of elementary bodies being often poly- atomic, a fact otherwise of undiscovered import. The exceptions afforded by monatomic gases and metals in- deed suggest themselves at once : but spectrum analysis shows that these molecules are intrinsically just as com- plex in sub-electric structure as the others, while the physical test of monatomicity perhaps only verifies that the components of the molecule are somehow so closely 42 Larmok, Physical Aspect of tJie Atomic TJieory. compacted that the thermal collisions do not induce sensible internal commotion. But it is time to conclude this discursive survey. We have recognised that the Daltonian molecular theory is still the indispensable guide, if we wish to continue con- structive efforts in the physical elucidation of nature, and are not content to take down our scaffoldings for the sake of logical symmetry, and, in the future, make the most of the edifice as it now stands. While we are certain with Dalton that molecules are very definite, identical, structures, it has been seen that, when we inquire into the detail of their constitution, though many guiding principles mainly of electric and spectroscopic types have been made secure, yet we have not much more than their distant analogy with familiar dynamical systems to aid us. But for many branches of the science know- ledge of detailed molecular structure is not required. The pioneering example of this kind was the kinetic theory of gases. The domain of electrodynamics is now securely founded on the displacements and movements of electrons, each of which may be considered merely as a point at which the unitary electric charge is concentrated, so small are the unknown nuclei of the electrons com- pared with their distances apart. In the same way the wide domain including the course and equilibrium of reactions in dilute systems can be studied by pure numerical statistics in the manner of Guldberg and Waage, or by the more generalised but fundamentally equivalent thermodynamic methods associated mainly with Willard Gibbs. But the aim of structural chemistry must go much deeper ; and we have found it difficult, on the physical evidence, to gainsay the conclusion that the molecular architecture represented by stereochemical Manchester Memoirs, Vol. Hi. (1908), No. 10- 43 formulae has a significance which passes beyond merely analogical representation, and that our dynamical views must so far as possible be adapted to it. We have recognised that the interaction of atoms at a distance apart, which is necessary to a cosmos, is provided for by a very special mechanism, consisting in the activity through the aether of the electrons that are attached to them. The artificial aspect of this arrangement would be relieved if we could assume these entities to be of the essence of atomic structure ; we are justified in following out this hypothesis as far as it can carry us ; and the totally unexpected phenomena of disintegration of com- plex atoms, very definitely detected, even in part predicted, by Rutherford and his colleagues and successors (Soddy, Ramsay, etc.), itself arising from Becquerel's and the Curies' discovery of spontaneous radio-activity, may ultimately lead us far. But there remains the question whether the facts of biology demand an underlying com- plexity in the atoms vaster than could be embraced in any definite physical scheme. Our conviction of an orderly connexion between things constitutes the conception of a cosmos. We have placed the foundation of this in the existence of a uniform medium, the aether, the physical groundwork of inter- stellar space, through which the actions between material bodies are established and transmitted. The idea of such a medium, when analysed mathematically, almost demands that matter should consist of discrete atoms, involving nuclei each of which binds together into permanence some mode of local disturbance in the medium. The illimitable complexity of the phenomena resides in matter ; but our grasp of the physical relations to which all its manifestations are subject arises from their being such as can be established through the aether. The 44 Larmor, Physical Aspect of the Atomic Theory. Daltonian principle of identity of all atoms of the same substance, — they are the same to the remotest limits of our universe, as Huggins demonstrated — may well arise from these atoms being the limited number of definite intimate types of structure into which more ultimate atoms can arrange themselves. These ultimate atoms would be limited as regards their relations at a distance, for they would in this respect involve only the few fundamental types of strain-centres which are capable of subsisting in the simple aether. The keystone of such a physical scheme is the aether : and the only ground for postulating the presence of this medium is the extreme simplicity and uniformity of the constitution which suffices for its functions. Needless to say, there remain many unresolved features, some still obscure, but hardly contradictory. But should it ever prove to be necessary to assign to the aether as complex a structure as matter is known to possess, then it might as well be abolished from our scheme of thought altogether. We would then fall back on simple phenomenalism ; proximate relations would be traced, but we need not any longer oppress our thought by any regard to a common setting for them ; the various branches of physical science would cultivate with empirical success independent modes of explanation of their own, checked only by the mutual conservation of the available energy, while the springs of their orderly connexion would be out of reach. That time, however, is not yet. Manchester Memoifs, Vol. Hi. (1908), No. 10 45 Appendix. On the Possible Types of Direct Chemical Combination.^ The question must often have arisen why chemical combinations and decompositions take place on a simple plan which can be represented as the addition to the molecule, or removal from it, of definite blocks or com- plexes of atoms, named radicles, which are therefore assumed to have a transient corporate existence; so much so that in a class of cases their existence has to be intro- duced explicitly in order to assist as carriers in the reactions. The physical analogy of an atom as a kinetic system of orbitally moving sub-atoms or electrons, such as is pointed to by its very definite intrinsic spectrum, would lead us to expect that, as a rule, tampering with the structure of a molecule by slicing off a block would lead to its total dissolution : while, on the other hand, the practically effective conceptions of organic chemistry suggest architecture rather than dynamics. Some light may perhaps be thrown on this subject by the consideration that it is only those structures that do fall to pieces in successive stages, and are thus capable of definite experimental dissection, that can have a chance of being produced in quantity, and of becoming segre- gated, in the clash of molecules amidst which all things chemical have their origin. In illustration, imagine a substance, say gaseous for simplicity, formed by the immediate instantaneous com- bination of three gaseous components A., B, C. When these gases are mi.xed, the chances are very remote of the occurrence of the simultaneous triple encounter of an • This Appendix was included substantially in a course of lectures at Columbia University, New York, in March, 1907. 46 LarmOR, Physical Aspect of the Atomic TJieory. A, a. B, and a C, which would be necessary to the imme- diate formation of an ABC; whereas, if ever formed, it would be liable to the normal chance of dissociating by collisions ; it would thus practically be non-existent in the statistical sense. But if an intermediate combination AB could exist, very transiently, though long enough to cover a considerable fraction of the mean free path of the molecules, this will readily be formed by ordinary binary encounters of A and B, and another binary encounter of AB with C will now form the triple compound ABC in quantity. The cognate subject of the dynamics of gas theory illustrates the point, in fact is closely implicated : that theory proceeds by aid of statistics of encounters, yet in its analysis triple and multiple encounters are left aside as negligible in number. The principle thus suggested, that immediate mole- cular combinations and dissociations are practically all binary, may have a wider application. It would tend to explain, as above indicated, how it is that in organic chemistry only those types of molecules — perhaps very few compared with what are in totality possible — have any chance of being isolated amid the chances of natural reactions, involving no control whatever of individual molecules, which can of themselves divide into parts or radicles of appreciable persistence, some of them replace- able by other such blocks or parts without allowing time for the dissolution of the whole. That science, in fact, proceeds by searching out and classifying the ways in which complex molecules may be thus definitely dis- sected and reconstructed. There is involved, on this view, the proposition that in the ultimate type of chemical interaction each molecule is divided into two parts at most, which it may inter- change with another molecule in the process of double MancJiester Memoirs, Vol. Hi. (1908), No. 10. 47 decomposition ; that in fact any transformation of more complex type than this must be expected to occur in successive stages. Thus the simplest case of a triple dissociation, say of a molecule ABC into A and B and C, may be held to occur in two stages, the first stage being such as a change into AB and C : the reason may be repeated, that without an intermediate diad stage the velocity of association of such molecules would be extremely slow compared with the velocity of dissociation of those already formed, so that in equilibrium the triad compound would practically not exist.* It appears indeed from the facts that chemical equilibria involving processes more complex than double decomposition occur but rarely. Where they occur at all, it is here suggested that there must be an inter- mediate stage, perhaps very transient ; and the question arises whether its existence may modify the usually accepted deductions from the Guldberg-Waage statistical representation of the chemical equilibrium, or the application of thermodynamics of which that theory forms one aspect. The matter will, however, assume a sufficiently com- plicated form, at any rate for initial consideration, in the very simplest example. Let us then examine the chemical equilibrium of a dissociating gaseous substance ABC, mixed with its components. Let this symbol ABC denote quantity of the substance ABC, measured in chemical equivalents, say by number of molecules per * Considerations such as these must often have occurred to molecular theorists. It is only recently (a year after this note was composed) that, in an obituary notice of Mendeleef by Dr. E. C. Edgar [Manchester Memoirs 51, 1907) a remark about "his persistent devotion to the Mendeleef-Gerhardt law, that gases combine only in equal volumes " has prompted a reference to the section on Atoms and Molecules in the " Principles of Chemistry," where views essentially equivalent to the above are powerfully supported on purely chemical grounds. [See footnote, p. 29 siipra.'\ 48 LarmoR, Physical Aspect of the Atomic Theory. unit volume, with similar meanings assigned for the other symbols. There can be present in the interaction seven substances, viz., ABC, AB, BC, CA, A, B, C, some of them perhaps of such slight permanence that they are not apparent. Of the amount ABC, suppose the quantity k^.ABC changes into ^C and A per unit time, k.^.ABC into CA and B, k^.ABC into AB and C : suppose the quantity a . BC dissociates into B and C per unit time, and so on : suppose/".^. C is the quantity which associates into BC per unit time, and so on; suppose l.BC.A is the quantity which associates into ABC per unit time from BC and A, and so on : — the coefficients a, b, c, k,. .. being proper fractions. Thus we have a scheme of formally possible transformations (^1 + h + k^ABC a . BC, b .CA,c. AB f.B.C,g.C.A,h.A.B I. BC. A, m .CA.B,n.AB. C. Ifany of these intermediate substances (say AB) is so transient as practically not to occur, the corresponding association factor (//) must be very small compared with the dissociation factor {c). When chemical equilibrium is attained, the dissocia- tions and associations continually going on do not alter the amount of the substance A ; therefore ki . ABC+ b.AC+c.AB~g.A.C-h.A.B-i.BC.A = o, and there are two similar equations. In the same way the constancy of the amount of the substance BC requires -kx.ABC+a.BC-f.B. C+l.BC.A = o, and there are two similar equations. Mancheste)' Memoirs, Vol. Hi. (1908), No. 10. 49 And the constancy of the amount of the substance ABC requires {k^ + h + k.^ABG -l.BC.A-m.CA.B-fi.AB.C=o. There are seven equations in all, but only four can be independent ; for the total amount of A that is present, free and combined, cannot change, therefore A + AB^-AC^ABC is constant, and there are two other such relations. This reduction is verified ; for adding any one of the first group of equations to the corresponding one of the second group gives the same result, viz., a.BC + b. CA + c.AB=/.B . C + g. C.A + h.A.B, and subtracting the sum of the first group from the last equation also gives this result. We shall take the second group and the last equation as the independent relations. To eliminate the inter- mediate substances AB, BC, CA, we have from the former ^^_Ai.ABC+f.B.C a + l.A and substituting in the last equation the value oi l.BC.A thus derived, If.A.B.C-ak^.ABC mg.A.B.C-bK ABC a + / .A d + m . B nh.A.B. C-cK.ABC = 0, c + n . C a complicated relation which, in conjunction with the expressions for binary combinations such as BC above, and the total atomic amounts of interacting material, determines the equilibrium. If //«, injb, n\c are very small, and 7^^, Ji correspond- ingly large, so that the intermediate compounds AB, BC, CA are all very transient, we have very approximately . (^+ '^+~)a.B.C= {k^ + k„^-^ k,)ABC, 50 Larmor, Physical Aspect of t lie Atomic Theory. which is the type of formula usually assigned for the ■equilibrium of a triple dissociation. When the amounts ■of interacting materials are given, this formula determines their distribution. If BC 2S\6. CA are very transient compared with AB^ we have lla and in\b very small compared with n\c^ while / and g are large compared with // if they take a sensible part in the equilibrium ; then ^A.B. C= (k, + k.^ + ^^3 — ^--y)ABa Ka b c+ n. Cj But if we suppose only five substances sensibly operative, say ABC, AB, A, B, C, the equations will be the (usual) binary ones, c.AB = h.A.B, k.ABC=?i.AB.C, yielding kc.ABC^Jm.A.B. C, which is a different law of equilibrium, being the same as if AB also did not occur. If A and B and C are identical, this latter law will hold universally : if only A and B are identical, it need not do so. Generally, the conditions for its validity are that /, m, n should be very small, or else lla = in\b = nlc. The tliei-nwdynamic condition of equilibrium employs conceptions and physical constants different from those pertaining to this statistical view of Guldberg and Waage, but at bottom connected and in ordinary cases leading to the same results. If ;//;, in^, vi.^, ;//,2,... denote the quantities of the different simple and compound substances that are present in any phase, and A the available energy, IA = + ^x■^h?^^ + jj.^m,^ + + iJi.^„}ni^„ + And as the available energy tends to a minimum, under the appropriate conditions, including constancy of tem- Manchester Memoirs, Vol. Hi. (1908), No. 10. 51 perature, any slight reactive change that can occur in the phase must leave A sensibly unaltered, provided equili- brium has arrived. Thus the thermodynamic potentials /ij, ^,, ^,„,... in the phase must satisfy a number of relations indicating the equilibrium of each possible partial reaction that can occur in it, e.g., as there is a reaction possible of type we must have /ii + ^, = ^1, . The thermodynamic potentials of all compound substances in the phase are thus found in terms of those of the simple (or other) independent constituents 1)1^, w,„ 1)1,. ; that is, the system will settle down to an equilibrium in which they have the values thus determined. If two phases coexist in contact, jUj, /u„, ju,., must moreover have the same values in both of them. If P phases can coexist, there are' thus r{P - i) conditions to be satisfied : and each phase has a char- acteristic equation of state connecting in, v, and the tem- perature T, — thus making up in all P conditions. Now there are independent variables rP in number, together with T, and the total volume v, — the portions of the volume occupied by the various phases being determined by their characteristic equations. The system will be wholly determined if P = r+2. This is, in fact, Willard Gibbs' theory limiting the number of phases that can coexist in given material, and conversely. The thermodynamic potentials that are here involved must be functions of the velocities of interaction of the previous analysis. But are they always consistent with the previous statistical view, without restriction? 52 Larmok, Physical Aspect of the Atomic Theory. In dilute solution /ioclog(;;//z'), thus we should have a relation ;//^7/A2/w,, = constant. Thus all the thermodynamic equations of equilibrium will take the form of the con- stancy of simple factorial ratios. Does this imply more than mere statistics of chance encounters can provide? It involves a further principle, that the reaction between ;//,, ;;/., and 7//^,, is in equilibrium by itself, just as if the other components containing the same elements were prevented by constraint from changing. If this principle of isolation of the equilibria of the component reactions is warranted, it produces extensive simplification not inherent in the customary statistical point of view : it can for instance specify at once the proportions of the inter- mediate compounds that are present, replacing a system of complex linear equations by constancy of simple ratios. If we may apply it to the problem on page 48, the equations there deduced will be replaced by k^.ABC^t.BC .A, f.B. C=a.BQ so that k,.ABC=^ A.B.C- a involving and also expressing the relative frequencies in which ABC splits up into different intermediate compounds. In further exemplification of the simplification thus introduced, consider the system N2O4, NO2, N, O ; if we' are sure, experimentally, that N and O are infinitesimal in a partial system NO., N, O, then they are so in the wider system, for by the equilibrium of the partial system N and O are determined. On this therinodynainic view it is in fact by trains of single or double decomposition that sttbstances are formed. MancJicster JlJ'cinoirs, Fo/. Hi. (190S), A^^. 10. 53 For if we do not admit this postulate, then the equations of statistical equilibriiim will contain more than two terms as exemplified above ; and that aspect of chemical equili- brium will be at variance with the usual thermod\'namic theory, which expresses an independent equilibrium for every type of reaction that is formally possible. And the reason has been already indicated, viz., the usual expressions for the thermodynamic entropy and available energy of gaseous s\-stems, and through them of dilute solutions, in- volvethe implication that onlybinary molecular encounters need be considered. The two points of view will agree only if all reactions take place in binary stages ; and it becomes a question whether this is a universal rule under all circumstances, or only one prevalent in the prominent cases which are naturally those governed by simple recognisable relations. An actual case in which these distinctions may make theoretically a difference is worked out from the thermo- dynamic side in Planck's TJicrniodyiimnics, §247, under the heading of graded dissociation, viz., that of hydriodic acid HI into H,, I,, and I. Another question in which such considerations may have scope is that of Ostwald's law of equilibrium of ionisation. If only two ions can arise, they must be equal in number ; thus \{ c is their concentration (dilute) and c that of the non-ionised part, c'-jc may be expected to be constant at each temperature, the ionisation proportional to c being balanced by the recombination proportional to c'-. But this assumes that all the ionisation is spon- taneous, whereas in the cognate phenomena of gases the encounter of an ion (in rapid motion) with a molecule has been shown by Townsend to be a potent cause of further ionisation. This suggests the question whether c should not be replaced by c-^kcc or <;• (i +/r'), which may 54 Laraior, Physical Aspect of tJic Atoiinc Theory. make a difference in the direction actually occurrinCT^ whenever the concentration of ions c is considerable. Moreover, the spheres of mutual electric influence of ions are far greater than those of molecules, which may also make a difference. It is, however, to be noticed that in the discussion above of the ordinary association of a substance ABC, this type of action, in which e.g. a component C acts in a special manner in breaking up a component ^Z?, has been excluded. The presence of such actions in which more than one cause contributes to the result would seem hard to adapt to the usual thermodynamic theory involving as we have seen independent binary stages of reaction. Manchester Memoirs, Vol. Hi. (1908), No. 1|. XI. Notes on the Greater Horseshoe Bat, Rhinolophus ferrum-equinum (Schreber), in Captivity. By T. A. Coward, F.Z.S. {Received and read February 2^th, igo8). In the winter of 1906-7 I paid a short visit to Cheddar, Somerset, in order to study the habits of the Greater Horseshoe Bat, and brought back with me two Hving bats, obtained in one of the caves on January 6th, 1907, for observation at home ; one of these survived a fortnight, the other five weeks. I published an account of my observations and conclusions (i), and propose to give an epitome of my paper, as it has considerable bearing upon my more recent notes. In the Cheddar caves I found numbers of Greater Horseshoe Bats scattered singly or in colonies. They were not in profound sleep, and moved their positions from time to time ; they were, in the evening, occasionally on the wing in the caves. On two or three evenings I saw bats emerge from a fissure in the roof of one cave and fly further into the cave, and on one night — January 6th, 1907 — Mr. C. Oldham, who had then joined me, and I watched bats emerge from this fissure and pass out of the cave into the open. On the floors of the caves, sometimes scattered and sometimes in little heaps, were the rejected portions of insects which had been devoured by the bats. These consisted of wings and other parts of moths, evidently captured in summer, and fragments of beetles, and of a cave-spider, Meta ntoiardi, Latr. The beetle remains consisted of the head, prothorax and first pair of April 2 IS.', igo8. 2 Coward, Greater Horseshoe Bat in Captivity. legs, and often with the mesothorax and elytra or one elytron attached, but the abdomen and wings had been in almost every case devoured. There was old dry dung in heaps, and more recently-dropped dung scattered about. Mr. R. Newstead examined the dung on my behalf, and found that the pellets dropped in summer contained about equal proportions of fragments of Lepidoptera and Coleoptera, and that about 44% of the coleopterous remains were those of some species of Geotmpes. The dung dropped in winter was almost entirely composed of remains of Geotrupes, and many of the rejected fragments found in the caves were of Geotrupes spiniger, Marsh. The elytra of a flightless beetle were also present in a few places in the caves. " The prey of the Greater Horseshoe," I wrote, " may be captured on the wing, but that it is not, as a rule, devoured whilst the bat is flying, seems to be proved by the behaviour of bats in captivity even more than by the presence of fragments of prey in the caves. When secured by a snap of the bat's jaws the insect is conveyed to some resting-place and there consumed." Over 120 beetles — Geotrupes typJiceus, Linn. — were eaten by my two captive bats, and in every case the behaviour of the bats was practically the same. " I usually held the bat in my hand until it had snatched the beetle and then released it ; — The released bat, holding the beetle securely, — flew to some favourite foothold, and there hung until the beetle was devoured. I never heard the sound of champing jaws as the bats were flying, but when they were at rest the noise of crushing the hard armour of the beetles was plainly audible. The interfemoral membrane was never used as a pouch, as it is in the Vespertilionidae (2), but the beetle was invariably pushed against the interbrachial membrane, as I observed was the case in the Lesser Manchester Memoirs, Vol. Hi. (1908), No. 11. 3 Horseshoe (3). As a rule one leg was detached from its hold in order to give more freedom to the half-outstretched wing on the same side." On December 28th, 1907, I received two female Greater Horseshoe Bats from Mr. Bruce F. Cummings, which he had taken two days previously in iron-workings in the Pickwell Down sandstone at Braunton, North Devon. These I had fed upon Geotrupes typhceus, and succeeded in keeping one alive for five weeks and the other nine weeks. For some ten days I was obliged to feed the bats by holding them in one hand and pushing beetles against their jaws with the other, but in less than a fortnight both would take proffered beetles, snatching them eagerly from my fingers. It was perfectly easy to distinguish one bat from the other, for they differed greatly in their tameness, and the younger and more familiar of the two had a large female tick {Ixodes vespcr- tilionis, C. L. Koch) on its back. This tamer bat was the first to take beetles from my fingers, to find them and devour them in its cage, and to catch them for itself on the wing. The tamer bat would frequently pitch on my hand or arm, brush in flight against my head, hang itself up close to my face, and show plainly in various ways that it wished to be fed. The other one was always wilder and more nervous, but it would, when suspended from my finger, allow me to carry it about the room, and drink when I held it over a saucer of water or devour a beetle without leaving my hand. The size of the cage in which I kept my bats is 18 ins. by 18 ins., and 24 ins. high; a bar of wood is fixed at 20 ins. from the floor of the cage from which the bats suspend themselves. In this somewhat limited space they were able to find and catch beetles which were left in the cage. When feeding the bats in the evening I 4 Coward, Create?- Horseshoe Bat in Captivity. always allowed them to fly about the room and pitch wherever they pleased. Considerably over 400 beetles were eaten by the bats, whilst the latter were at rest. The exceptions were so few that I have no hesitation in asserting that it is the rule for the species to devour its prey when it is at rest. Two or three times I detected the sound of crunching when a bat was on the wing with a beetle in its mouth, but on these occasions the bat pitched before it dropped the beetle's head and elytra ; in one instance only was a beetle wholly devoured without the bat alighting — the discarded portions being dropped in flight ; but even in this exceptional case the bat three or four times attempted to find but failed to secure a foothold. It is very doubtful if the Greater Horseshoe has keen sight ; indeed, though the action of the bat when hanging by its feet and fully awake, suggests that it is looking round — a rapid, nervous movement of the head, slightly raised, it does not seem to notice beetles which are held in front of it, or to be able to quickly locate them when they are crawling near it on the ground. I have mentioned that the bats found and ate beetles in their cage. I frequently watched them do this, and also saw them, when at liberty in the room, drop on the floor near a beetle ; but even if the beetle was only a couple of inches beyond the bat's muzzle, it did not seem to be able to see it ; but if the beetle touched the bat it was secured. The Horseshoe Bats are unable to walk, but they have a habit of dropping with outstretched wings upon a flat surface, from which they spring again with surprising agility. On one occasion a bat dropped near a beetle which had buzzed, for undoubtedly the buzzing of a beetle at once attracted the bat's attention ; the bat moved its head to and fro, the lower edge of the horse- Manchester Memoirs, Vol. liu (1908), No. 11. 5 shoe touching the floor. The beetle walked a few inches away, and then again attempted to fly ; instantly the bat followed it in a series of little jumps, really short flights of a few inches, and after two or three jumps reached and fell upon the beetle, which it at once thrust into its interbrachial membrane. Directly it had secured the beetle it rose from the floor, flew to a customary perch and, there hanging, consumed it. In the cage the method was similar ; the bat dropped on to the floor of the cage, lying with extended wings and either feeling or smelling round — at least that was what the action suggested — until it found a beetle ; directly one was secured, it sprang up, turned in the air, and clutched the bar of wood, only twenty inches above it, with its feet. The beetle was then pushed into the wing as usual, and the head and perhaps other fragments dropped. This, then, is evidently the way in which flightless beetles and spiders are caught, and possibly coprophagous beetles may be thus picked up when they are crawling over dung. This is, however, not the only way in which the Greater Horseshoe secures its food ; it can and does catch insects on the wing. G. typhosus is a beetle which flies during mild weather in winter, and when I released a dozen beetles in my room in the evening, two or three would quickly attempt to fly. It was when this occurred that I felt certain that the bats hunt and locate their prey mainly by means of their acute hearing. The deep booming buzz of the flying beetle at once roused the Horseshoes to activity, even when, as was often the case after eating two or three beetles, their heads were drooping, and they were relapsing into sleep. Usually the bat left its foot- hold immediately the beetle began to buzz, and as these beetles are not always quick in getting on to the wing, the bat frequently skimmed over and missed its prey. But 6 Coward, Greater Horseshoe Bat in Captivity. when the beetle had risen two or three inches from the ground, it was doomed ; the bat came down hke a falcon stooping, and with marvellous precision caught the flying beetle in its jaws, and carried it off to some place where it could pitch and devour it. For several weeks this performance was repeated on an average two or three times each night, and though on a few occasions the beetle got well into the air before it was captured, by far the greater number were secured before they had risen many inches from the ground. In order to watch closely the method of devouring food I frequently allowed the bats to hang from my fingers and gave them beetles. If the beetle was small it was eaten without any assistance from the wing ; the larger the beetle the more vigorous the action of the bat. When a large beetle was seized it was at once thrust into the posterior portion of the interbrachial membrane. The claws of the leg on the side thus used were usually released from their hold, and the whole wing brought suddenly forward, by simultaneous stroke of arm and leg, to meet the head. The beetle was practically beaten against the membrane by rapid movement of the bat's head, assisted by the forward stroke of the wing. This wing-action, suggestive of the use of a hand, has no exact parallel in the apparently similar use of the interfemoral pouch by vespertilionid bats. The beetle was moved by the bat against the membrane, for its position in the mouth had frequently to be shifted before the bat could devour the abdomen and reject the head ; and sometimes the action of head and wing together actually pushed the beetle further into the mouth. When the beetle was first seized the wings of the bat were only slightly unfolded, held free but with the membrane partially hiding the body, and when the bat took a beetle from the hand it MancJiester Memoirs^ Vol. hi. {igoZ), No. 11. 7 beat rapidly with both arms but did not grasp with the thumb. Directly the beetle was in the bat's jaws the wings were further opened, and hung quite loosely whilst the beetle was being devoured. After a few seconds the head was withdrawn from the wing and the beetle masticated ; the rejected portions fell, and the bat, generally suspended by one leg, swung from side to side. This swinging round was even more remarkable when both feet were attached to some hold ; the animal could then turn almost completely round, crossing its legs, without altering the position of its feet. When the beetle was finished, the bat usually bent forward, and two or three times touched the object from which it was suspended lightly with its lips ; this was especially noticeable when a bat had been feeding when hanging from my hand. Frequently, also, one leg was brought forward, and the teeth scratched or the lips combed by the claws, probably to get rid of some par- ticles of beetle which were sticking to the teeth or lips. When the beetle was quite finished and the sub- sequent performances had been gone through, the bat hung, bending its whole body forward, turning from side to side, and moving its head, ears and nose-leaf with great rapidity ; it appears to be looking for food, but perhaps searching for prey would be a more correct way of expressing it. At first the number of beetles eaten per bat was from 5 to 8 each night, but later, when they were regularly feeding themselves, they took so many as 10 or 12, and even occasionally 16 in a night. The number did not depend upon the number left in the cage, for frequently beetles were untouched in the morning; this may, however, have been due to inability on the part of the bats to find and secure them all. 8 Coward, Greater Horseshoe Bat in Captivity. The bats preferred living beetles to dead ones, and though I now and then managed to trick a bat into eating one which had been killed, it was the exception rather than the rule. Generally the bat would over and over again refuse a dead beetle which was offered to it, although it would at once seize one which was alive, even though the beetle was feigning death. It is quite likely that the bat could smell the difference, for a dead Geotriipes has a noticeably unpleasant odour. The Horseshoe drinks by lapping with the tongue. It is a thirsty animal, and we can only suppose, from its behaviour in captivity, that it obtains water in its natural state ; possibly, like other bats, it hovers over pools of water and laps whilst on the wing. The Greater Horseshoe is famous for its wonderful power of flying round and amongst obstacles without touching them with its wings, but when it is dashing after its prey it pays little attention to its surroundings. On one occasion a bat caught a beetle near the floor, and in its headlong dash bumped, with the beetle in its mouth, into the leg of a chair ; on another, bat and beetle came full tilt against my waistcoat. Once or twice the bat fell to the ground, but, having secured the beetle in its dash, rose at once with its prey. Occasionally, however, a beetle was captured with more deliberation. The bat would fly to it, hesitate in its flight, hover a second, gently snap the beetle, and at once return to its perch. The temperature in the Cheddar caves and in the old mines at Braunton is fairly constant, about 52°F. I attempted to keep the temperature of the room in which I kept my bats as even as possible, but found it very difficult to do this during the frosts in January. At Cheddar the bats became active at dusk, but as a rule my captives did not awake until late in the evening, generally Manchester Memoirs, Vol. Hi. (1908), No. 11. between 11 p.m. and 11-30 p.m. On several nights the bats did not awake at all, and on some only one was active ; a table of dates with temperatures in the room and in the open shows a remarkable irregularity, which Date. Temp. in Room. Temp. in Open. Time of Awaking. Number of Beetles Blaten. Remarks. Highest. Lowest. 8a.m.iop.m. No. I. No. 2. No. I. No. 2. Dec. 29 30 F. 34° 36° F. 36° 36° 5 5 Both awoke, but time not taken. Did not wake. ,, 31 35° 34° p.m. 10-45 p.m. 11-30 8 5 Jan. I 2 36° 30° 35° 32° Did not wake. 5) )> >) 3 28° 28" II-O II-O 7 6 >> 4 26° 27° 11-30 8 No. I did not wake. »' 5 22° 18" Did not wake. ,, 6 50= 38° 39° 45° 11-30 5 No. 2 did not wake. ,. 7 56° 48° 46° 41° II-I5 11-30 5 5 j; 8 54° 46° 39° 39° ... Did not wake. >> 9 51° 42° 33 31° ... ,, » 10 48° 44° 25° 25° )> >> ., II 48° 40° 32° 31° II-O 9-30 6 8 42° at 9-30 p.m. in room. » 12 50° 40° 27° 28° 9-30 2 Only No. 2 woke. .' 13 50° 40° 28° 38° Did not wake. )) 14 46° 42° 39° 44° awoke awoke both fed. Times not taken. »J 15 49° 42° 45° 50° both awoke but parti culars not taken. After this both bats awoke and fed regularly. can, I fancy, only be explained by the altered conditions under which the bats were living in confinement. On the night of the 8th, for instance, when the temperature lO Coward, Greater Horseshoe Bat in Captivity. had been high during the previous 24 hours, neither bat awoke, but on the night of the i ith, when the temperature had been, for the room, decidedly low, both bats awoke and fed. When the average temperature had been practi- cally the same on the three nights of nth, 12th, and 13th, both awoke on one night, one on the next, and neither on the third. Sight, in the Greater Horseshoe, is, as I have said, apparently not acute. When we compare the small eyes, almost buried behind the facial ornaments, with the large prominent eyes of the Long-eared Bat, Plecotus aiiritiis, Geoffr., a species which apparently uses its eyes when feeding, we can hardly imagine that they are of much service to the animal. Nevertheless it not only locates flying food with remarkable certainty (I have suggested by sound), but can at once discover the exact situation occupied by another bat. Frequently when both bats were at liberty in the room, and one had pitched and was quiet, the other would fly to it without hesitation and pitch beside it or actually upon it. On such occasions there was nothing to suggest that the one bat heard the other, but when one was crunching a beetle, and the other hovered round it, pitched near it, and, as happened more than once, took a portion of the uneaten beetle from the mouth of the original captor, it may easily have been guided by sound. The normal position of the sleeping Greater Horse- shoe is similar to that of the Lesser Horseshoe (4), which has been frequently described, but the tail is often more visible, standing out at an angle of about 30°. When the bat is disturbed in sleep it draws itself up by bending the legs (as shown in the photograph taken in a Cheddar cave), and when slowly awakening will hang with the legs bent and the wings slightly unfolded. The bat pants and Manchester Memoirs, Vol. Hi. (1908), No. 11. 11 throbs, especially in the abdominal region, but it is not until it is nearly awake that it begins to move its head, ears, and facial adornment. When fully awake these are in constant rapid movement. The conclusions in my former paper (i) were confirmed by the behaviour of my recent captives. I remarked (p. 322): — " i. The Greater Horseshoe, if the weather be open at the end of December and beginning of January, is not in a state of hibernation, It moves in the caves, awakening without artificial stimulus, and leaves the caves apparently in search of food." In captivity we cannot get rid of " artificial stimulus " entirely, but my bats awoke, as a rule naturally, night after night, but during the frosts they occasionally slept for one, two, or three nights without awakening, although the temperature in the room was considerably higher than in the open. " 4. Food is conveyed into the caves from without and devoured there, the bats hanging whilst they feed." My bats certainly show that it is a rule to carry food to some foothold before devouring it. " 5. Certain creatures are captured and eaten in the caves." "6. Creatures incapable of flight are captured by the bats and devoured." By seeing the bats pick up beetles from the carpet or from the floor of the cage I was quite satisfied that they find and catch spiders and flightless beetles in this way, in the caves and probably also in the open. But from the way in which the bats skilfully secured flying beetles it is perfectly evident that in the free state they constantly secure their food on the wing. Mr. Bruce F. Cummings kept, for a few days, a Lesser Horseshoe Bat 12 Coward, Greater Horseshoe Bat in Captivity. which caught house-flies in a room in exactly the same way. «' 7. When feeding the Greater Horseshoe makes use of the interbrachial membrane and not of the interfemoral pouch." This was confirmed by a much larger number of experiments than I was able to make in 1907. REFERENCES. 1. Proc. Zool. Sac. 1907, pp. 312—324. 2. Oldham, Zoologist, Sen 4, vol. 3, pp. 471—474 (1899). 3. Proc. Zool. Soc, 1906, pp. 849—855. 4. Oldham, Manchester Memoirs, vol. 49. No. 9, pp. 6, 7 (1905)- EXPLANATION OF PLATES. 1. Ventral view of Greater Horseshoe Bat in normal sleeping position. 2. Greater Horseshoe photographed in cave at Cheddar. This bat had not been touched, but it had drawn itself up by bending its legs. 3. Bat awakening from sleep; the body was moving* spasmodically, and the ears are slightly bent. 4. Bat devouring a beetle ; hanging by one leg ; the inter- brachial membrane on the left side was in use in this case, and the left foot is hanging free ; the head was in rapid motion. Manchester Uleinoirs, Vol. LI I. {No. II). Plate, Fig. I. Fig. 3. Fig. 2. Fig. 4. Manchester Memoirs, Vol. Hi. (1908), No. \%. XII. Action of Selenium and Tellurium on Arsine and Stibine. By Francis Jones, M.Sc, F.R.S.E. Received and Read March loth, igo8. In a paper on Stibine, read before the Chemical Society of London and published in the Journal for 1876, page 641, I pointed out that sulphur decomposes the gas in presence of light, with formation of hydrogen sulphide and antimony trisulphide which deposits on the sulphur. Further that the liberated hydrogen sulphide also reacts with stibine producing antimony trisulphide and free hydrogen. (a) 2SbtL + 6S=Sb,,S3+3H„S. \b) 2SbH, + 3H,S = Sb,,^3 + 1 2H. It was shown that the reaction serves as an extremely delicate test for stibine, and it was also used to determine its composition, by estimating the amount of antimony deposited as sulphide on the sulphur, as compared with the amount of hydrogen in the hydrogen sulphide evolved. The value of this method for determining the composition of certain hydrides, has since been shown by its application to the case of germanium hydride which is also decomposed by sulphur. \^Z eitschrift fiir Anorganische Chemic, vol. 30, page 3.15, Uber Germanium- wasserstoff von E. Voegelen.] I also showed that sulphur acts similarly on plios- phine and arsine, but not so readily as in the case of stibine. April 22nd, igo8. 2 Jones, Selenimn and Tcllurimn on Arsine and Stibine. It appeared probable that the elements selenium and tellurium, which are analogous to sulphur, would act in a similar way with arsine and stibine and I have now to record the results of experiments made to decide this question. In the course of these experiments it was necessary to have distinguishing tests for the hydrides of sulphur, selenium and tellurium which are so alike in their reactions. Each of these hydrides produces on paper moistened with solution of lead acetate, dark stains which are extremely similar, and I was unable to find any tests recorded which would serve to distinguish them. On trying the effect of various reagents upon these stains I found that hydrogen dioxide and hydrochloric acid were useful for this purpose, at all events in the case of a distinct stain. The differences in the behaviour of these stains with reasfents are shown in the following table : — Stain. H.,0„. HCl. (dilute). HCl. (strong). Lead Sulphide. Lead Selenide. Lead Telluride. Stain rapidly fades and leaves paper white. Stain slowly fades and leaves orange coloured stain (selenium) Stain fades in course of time. Stain fades almost instantly and leaves paper white. Stain slowly fades and leaves orange coloured stain. Stain fades only slightly and leaves greyish black stain. Stain instantly fades and leaves paper white. Stain slowly fades and leaves orange coloured stain. Stain fades only slightly and leaves greyish black stain. These reaction.? were employed to discriminate between the lead stains obtained in the course of the Manchester Memoirs, Vol. Hi. (1908), No. VZ. 3 experiments, except in those in which arsine was used, as this gas acts directly on solutions of lead and pro- duces stains on paper moistened with lead acetate very similar to the others. This reaction will be referred to subsequently. Action of Sclcniiiin on Arsine. {a) In snnligJit. The arsine employed was generated in the way described in the paper already referred to, that is to say, a solution of arsenious acid in dilute hydrochloric acid was allowed to drop from a stoppered funnel tube into a gas bottle filled with pure granulated zinc. The exit tube from the gas bottle passed to a wash bottle containing dilute soda, and the exit tube from this passed to a drying tube filled with calcium chloride. The gas so obtained then passed into a tube containing powdered selenium exposed to sunlight. Under these circumstances the selenium became slowly coated with a deposit of arsenic selenide, arsenic being easily detected in the contents of the tube. A reaction exactly similar to that occurring when arsine is passed over sulphur exposed to light therefore takes place, although more slowly : 2 AsH„ + 6Se = AsoSe, + sH.Se. Just as in the sulphur experiments, a secondary reaction was found to take place between the liberated hydrogen sulphide and the arsine, resulting in the formation of arsenic sulphide (which deposited on the glass tube) and free hydrogen, so in the selenium experiment, after prolonged exposure to sunlight, the glass tube was found slightly coated with arsenic selenide, due to the reaction of the liberated hydrogen selenide on the arsine, thus 2 AsH„ + sH^Se = AsaSe. + 1 2H. 4 Jones, Selenium and Tcllnrhiui on Arsinc and Stibinc. {b) At a teniperatnre of lodC. Arsine was passed over selenium contained in a U-tube which was immersed in boiHng water, and the whole apparatus was screened from daylight. There was no difference in the appearance of the tube at the con- clusion of the experiment, and on testing the contents the absence of arsenic was proved, so that arsine is not decomposed by selenium at the temperature of boiling water. ic) In tJic dark. Arsine was passed over selenium contained in a tube screened from light. The gas was jaassed for several hours but no reaction occurred. Action of Tcllnriiini on Arsine. (a) In sunlight. Arsine was passed for three hours over powdered tellurium contained in a straight glass tube. At the end of the experiment there was no visible change in the appearance of the tellurium, but on removing it from the tube and heating it in a test tube, a sublimate formed which, under the microscope, was seen to consist of distinct octahedral crystals. These were dissolved in water, hydrochloric acid and sulphuretted hydrogen were added, and a yellow precipitate of arsenic tri-sulphide appeared. So that in presence of sunlight, tellurium decomposes arsine. {b) At a temperature of loo'^C. Arsine was passed over powdered tellurium contained in a U-tube protected from light and kept at a tempera- ture of lOO^C. After more than three hours treatment the action was stopped and the contents of the tube tested Manchester Memoirs, Vol. lii. (1908), No. 1*^. 5 for arsenic as in the preceding experiment, but not a trace of arsenic was detected. {c) In the dark. The experiment was repeated at the ordinary tem- perature for the same length of time, but no arsenic could be detected in the contents of the tube. Action of Selenium on Stibine. (a) In sunlight. Stibine, prepared in a similar manner to arsine as above, was passed over powdered selenium contained in a glass tube exposed to sunlight. The escaping gas was passed over paper moistened with solution of lead acetate. This very soon blackened and the stains produced were not rapidly removed either by hydrogen dioxide or hydrochloric acid, and after a time they became orange coloured owing to separation of selenium. During the experiment it was noticed that a brown film slowly formed on the glass tube containing the selenium, showing that in this case also a secondary reaction occurred between the liberated hydrogen selenide and the stibine : 2SbH3 + 3H.^Se = SboSe, + 1 2H. {b) At a temperature of 100° C. Stibine was then passed over powdered selenium contained in a U-tube immersed in boiling water and -screened from light. As the selenium melts so readily that it might stop the passage of the gas, small portions were placed in the U-tube, separated by plugs of cotton wool. At the exit a tube was placed containing paper moistened with solution of lead acetate. Soon after the experiment began, the lead paper became stained and eventually was 6 Jones, Selcnhun and Telliiriuui on Arsine ajid Stibmc. blackened all over. The stains were not removed by treatment with either hydrogen dioxide or hydrochloric acid, so that selenium decomposes stibine at the tempera- ture of boiling water. \c) In the dark. Stibine was passed over powdered selenium contained in a straight glass tube and screened from light. A paper moistened with lead acetate solution was placed between the stibine apparatus and the selenium tube, and another at the exit of the apparatus. When the gas had passed for half an hour the first paper was quite unaltered, but the second was stained half its length. The experi- ment was continued and ultimately the second paper was blackened all over. The stains were not removed by hydrochloric acid, so that, even in the dark, stibine is decomposed by selenium. This reaction was so remark- able and unexpected that the experiment was several times repeated with the same result. Of all the hydrides examined in contact with sulphur, selenium, and tellurium, stibine is the only one to be decomposed in the dark at the ordinary temperature, and then only when in contact with selenium. Action of Tellurium on Stibine. (a) In sunlight. Stibine was passed over powdered tellurium contained in a straight glass tube and exposed to sunlight. The exit tube contained a paper moistened with solution of lead acetate. This paper became darkened after the pro- longed action of the gas, and the stains were not removed when placed in hydrochloric acid, so that stibine is slowly decomposed in presence of tellurium exposed to sunlight. MancJiesier Mejuoirs, Vol. Hi. (1907), A'^^. 12. 7 (It) At a temperature pf lod" C. When stibine was passed over tellurium kept at a temperature of ioo°C., the lead paper was distinctly stained after the prolonged passage of the gas, and the stains were not removed by hydrochloric acid. (r) /;/ tJic dark. In a similar manner, stibine was passed over tellurium, but in the dark and at the ordinary temperature no reaction took place. The results of the investigation, including those of the previous paper in which sulphur was used, may be tabulated as follows : — /// sniih'jihi. Element. Hydride. Result. Element. Hydride. Result. Sulphur AsH„ Reacts slowly Sulphur SbH. Reacts easily Selenium A.sII„ Reacts Selenium ... SbH„ Reacts easily Tellurium ... AsH, Reacts Tellurium ... SbH„ Reacts At \oo°C. Sulphur AsH„ Reacts slowly Sulphur SbHj Reacts slowly Selenium ASH3 No action , Selenium ... SI)H.. Reacts slo\\Iy Tellurium ... AsHj No action , Tellurium... /;/ the dark. SbH, Reacts very slowly Sulphur AsII„ No action Sulphur SbH3 No action Selenium AsH„ No action Selenium ... SbH 3 Reacts Tellurium ... AsH., No action Tellurium ... Sbllg No action In the previous paper I pointed out that the facility of the decomposition of the hydrides of phosphorus, arsenic, and antimony by means of sulphur when exposed to light, increased with the rise in the molecular weight of these gases, phosphine being very slowly decomposed, arsine more rapidly, and stibine very rapidly. Similarly, it is now '.". ..Hft. 3, von R. Jecht (8vo., Gorlitz, 1907), presented by the Oberlausitzische Gesellschaft der Wissenschaften ; '•'' Seismogramme des nord- pazifischen u. siidamerik. Erdbebens, 16 Aug., igo6 " [with Diagrams], von E. Rudolph u. E. Tarns (4to. and fob, Strass- burg i. E., 1907); '•'■ Katalog der im Jahre ig04 registrierteii Seismischen Siornngen" von E. Rosenthal (4to., Strassburg i. E., 1907); "Z^5 Tremblenients de Terre resseniis pendant Fannie, 1904," par E. Oddone (4to., Strassburg i. E., 1907), presented by Professor A. Schuster, F.R.S. The President briefly referred to the death of Lord Kelvin, and mentioned that he had, in his capacity as President, represented the Society at the burial in Westminster Abbey, and at his suggestion it was resolved that the Society express, through their Council, to the family of the deceased man of science, their sense of the great loss sustained, through Lord Kelvin's death, by the world of science, and by this Society, of which he had been an Honorary Member since 1851. Mr. T. A. Coward, F.Z.S., exhibited a live specimen of the Greater Horse Shoe Bat { Rhinolophus ferrtwi-equinum) and briefly described its chief peculiarities. Dr. E. C. Edgar read a paper entitled "The Atomic weight of Chlorine," which is printed in the Memoirs. Mr. A. Brothers read a paper entitled '* On the Pro- duction of Photographs in the Colours of Nature," faiiiKvv r^f//, /t^c'cS'.] Proc'EEDINGS. xiii of which the following is an abstract : — The development of colour photography dates hack to the early part of the nine- teenth century. The earliest methods were suggested by the discovery that a solar spectrum decomposes silver chloride, giving rise to a sympathetic colour change in the salt. (Seebeck 1810, Herschel, Zenker, Du Hauron, Lippman and many others). The next method consisted in using collodion plates (Abney and others) but no reliable means of fixing the pictures was known. The pictures obtained by the late Mr. Joseph Sidebotham — one of a red geranium with green leaves, and another of a landscape showing a red-tiled house and trees in shades of green — were accidental, and were never repeated, and it is curious that these results were fixed while others were quite fugitive. The introduction of orthochromatic plates made it possible to produce effects in colour not otherwise obtainable. As early as 1873, Dr. Vogel used gelatine bromide plates, and in 1879, Mr. F. E. Ives used coUodio-bromide plates and obtained excellent results which could be used in the optical lantern. Three negatives were required, each taken through a differently coloured medium, the colours used being bright red, puiple-blue and green. Transparencies wtre made which had the ordinary appearance except that they varied in density. To produce the colour effect three lanterns were used, the pictures were projected through the same coloured media, their images superposed, and the resulting picture approached very nearly the colours of nature. Ives also used an instrument called the Kromscop, which was stereoscopic and gave beautiful results. Mr. Thorp, too, devised an instrument which showed effects very similar to those of the Kromscop. Trichromatic printing or the "three-colour" process is the outcome of the work alluded to here. In this process, negatives are taken through colour- screens. '1 he block from the negative of the red is printed in blue ink, that from the green, in red, the one from the blue in yellow. The combination of the three pigments gives results which, in the ordinary way of colour printing, can only be obtained by using from 5 to 15 or 20 colours. xiv Proceedings. [Jauuary 14th, igo8. The nearest approach, it seems to me, to what has been the aim of so much research, may now be seen in the Autochrome Photography of Messrs. Lumiere, of Lyons. Some details of the process were pubhshed by the authors some years since, but it is not possible to give full particulars here. The exact method of preparing the plate is not published, but it is known that the plates are coated with starch grains stained in three colours — violet, bright green, and bright orange. The glass has a tacky coating, and on this the starch grains are spread in an even layer, by dusting or otherwise. The spaces between the grains are filled with a black pigment. This method is now said to be modified by crushing the granules until they fill up the spaces so as to cause the light to pass through the starch only. A coat of varnish protects the plate which is afterwards overlaid with an emulsion sensitive to the red rays. The plate is then ready for exposure in the camera. The photograph is taken through a yellow screen, the glass side of the plate being placed towards the lens. The chief advantage of the new method is that, after the production of the plate, the ordinary routine of photographic work is all that is required to produce the transparency in colour. General Meeting, January 28th, 1908. Professor H. B. Dixon, M.A., F.R.S., President, in the Chair. Mr. Thomas William Fox, M.Sc.Tech., Professor of Textiles in the School of Technology, Manchester, zj, Clarendon Crescent^ Eccies, and Mr. William Myers, Lecturer in Textiles in the School of Technology, Manchester, Sfone Edge, Marple, were elected ordinary members of the Society. January 2StIi, igoS.'] Proceedings. xv Ordinary Meeting, January 28th, 1908. Professor H. B. Dixon, M.A., F.R.S., President, in the Chair. The thanks of the members were voted to the donors of the books upon the table. The President stated that on March 3rd, the occasion of the Wilde Lecture, the Lecturer, Dr. J. Lakmor, Sec.R.S., would be entertained at a dinner in his honour at the Midland Hotel, and the price of the tickets would be 7s. 6d., and not los. 6d. as formerly. The attention of the members was directed to the publi- cations of the International Seismological Association which were on the table and were presented to the Society by Professor A. Schuster, F.R.S. They consisted chiefly of a number of carefully prepared and important diagrams of earthquake move- ments which occurred in the North Pacific and South America in August, 1906. The thanks of the meeting were voted to Professor Schuster for his interesting and valuable gift. At this point the chair was occupied by Professor H. Lamb, LL.D., D.Sc, F.R.S. Mr. A. Stephenson read a paper entitled " On a New Type of Dynamical Stability." The paper is printed in full in the Memoirs. General Meeting, February nth, 1908. Professor H. B. Dixon, M.A., F.R.S., President in the Chair. Mr. H. Bateman, B.A., Reader in Mathematical Physics in the University of Manchester, was elected an ordinary member of the Society. xvi Proceedings. [Febnuny nth, igo8. Ordinary Meeting, February nth, 1908. Professor H. B. Dixon, M.A., FRS., President, in the Chair. The thanks of the members were voted to the donors of the books upon the table. Mr. C. L. Barnes, M.A., and Mr. H. B. Knowles, M.A., were nominated Auditors of the Society'^ Accounts for tlie Session 1907-08. Professor E. Rutherford, D.Sc, F.R.S., read a paper written in conjunction with Dr. H. Geiger, entitled : — " A Method of Counting the Number of a-Particles from Radio-active Matter." The paper is printed in the MeiiioifS. Special Meeting, March 3rd, 190S. The President, Professor H. B. Dixon, M.A., F.P.S., in the Chair. The Wilde Lecture on " The Physical Aspect of the Atomic Theory," was delivered by Professor Joseph Larimor, D.Sc, Sec.R.S. Afterwards the President presented to Professor Lahmor the Wilde Medal which had been awarded to him that session by the Council. Fcbruarv 2jth, /po^.] PROCEEDINGS. xvii Ordinary Meeting, February 25th, igo8. Professor H. B. Dixon, M.A., F.R.S., President, in the Chair. The thanks of the members were voted to the donors of the books upon the table. Dr. W. E. HoYLE, exhibited several well-preserved examples of fossil insects which were sent to the Manchester Museum from Shiobara, Japan, by Dr. Marie C. Stopes. Three were Diptera, one being probably a Calypterate, whilst another was a remarkably well-preserved mosquito probably of the family Culicidae, another appeared to be a Culicid larva, whilst the remaining specimen strongly resembled a Machilis. They were all derived from 'J'ertiary deposits and were probably of Pleistocene age. No systematic work, however, seems to have been done as yet on these strata. Mr. T. A. Coward, F.Z.S., read a paper entitled " Notes on the Greater Horseshoe Bat {Rhi?iolophns ferrum- equinum) in captivity," which is printed in the Memoirs. The Chair was taken at this point by Mr. Francis Nicholson, F.Z.S. Miss Mary McNicol, M.Sc, read a paper entitled "On Cavity Parenchyma and Tyloses in Ferns,' of which the following is an abstract. Cavity parenchyma, a tissue replacing to a greater or less degree, the protoxylem of the petiolar bundles, has been recorded in all the large groups of true Ferns, and also in the Water-fern Alarsilia. In Miaolcpia, one of the Polypodiaceae, which represents a typical example, there is in the leafstalk a single curved bundle with slightly hooked ends : in each bundle there are generally five or six protoxylem groups, and of these one is found at each hook of the bundle, the other three or four lying in intermediate positions. The tissue is formed by the enlargement of the cells of the parenchymatous layer surrounding the xylem : these cells press in between the xviii Proceedings. {^February 2^th, igoS. spirally thickened portions of the vessel and by the enlarge- ment of the tylose-like processes so formed, break up the vessels, replacing them by a strand of large-celled parenchyma. In Nephrolepis the passage of undivided xylem sheath cells through a series of two or three vessels can be seen. Other plants examined in which cavity parenchyma is present, were StrutJiiopteris, C/ieila>ithes, Gyinnograinme, Pteris, Marattia, Angiopferis, Osmunda, G/eichenia, Aneimia, Hehninthostachys, Alsophila, Dicksonia, Heiiiitelia, and Cibo/iuin. In the last named occurred a condition not found in any other plant. Throughout the length of the strands of cavity parenchyma, some of the cells were lignified in a reticulate manner as tracheids resembling the " Speichertracheiden " described by Haberlandt. These lignified cells occurred sometimes singly sometimes in groups, but the groups were not connected with each other, and were thus probably not for conducting, hut for storage purposes. The other cells of the strand were of the usual soft-celled type. The occurrence of such tylose-like formations in recent ferns may be compared with the tyloses filling up the metaxylem tracheids in some of the fossil ferns, as in Rhachiopteris insignis, their presence in this case being due to the activity of all the cells of the xylem sheath and not simply of those bordering on the protoxylem. General Meeting, March loth, 1908. Dr. VV. E. Hoyle, F.R.S.E., Vice-President, in the Chair. Mr. W. H. Fowler, M.Inst.C.E., was elected an ordinary member of the Society. jMarcJi loth, igoS^ PROCEEDINGS. xix Ordinary Meeting, March loth, 1908. Dr. W. E. HoYLE, F.R.S.E., Vice-President, in the Chair. The thanks of the members were voted to the donors of the books upon the table. The following were among the recent accessions to the Society's Library : — '■'• BibliograpJiia Litnmenna " ...part. I, livr. i, par J. M. Hulth (8vo., Uppsala, 1907), pre- sented by the K. Vetenskaps Societeten i Upsala ; " Report on the geology ...of... Nor thivest Quarter-St. No. 122,'" by R. W. Ells (Svo., Ottawa, 1907); " The Barytes deposit of Lake Ainslie and North Cheticamp"hy H. S. Poole (Svo., Ottawa, 1907) ; ''Report on the Cascade coal basin Alberta " [with maps], by D. B. Dowling (Svo., Ottawa, 1907); '' Moose Mountain District of Southern Alberta,'' by D. D.' Cairnes (8vo., Ottawa, 1907); "■ Report of the section of Chemistry and Mineralogy''' (Svo. , Ottawa, 1906), presented by the Geological Survey of Canada ; " The Great Trigonometrical Survey of India f vol. iS (4to., Dehra Dun, 1906), presented by the Trigonometrical Survey of India; " Skeletal Remains suggesting or attributed to early man in N. America f by A. Hrdlicka (Svo., Washington, 1907), pre- sented by the Bureau of American Ethnology ; and " A Mono- graph of the British Annelids f vol. 2, pt. i, by W. C. Mcintosh (fol , London, 190S), purchased from the Ray Society. Mr. Henry Sidebottom read a paper entitled — " Report of the Recent Foraminifera from the Coast of the Island of Delos (Grecian Archipelago), Part V." Many beautiful drawings of Foraminifera were exhibited, and some mounted specimens were shown under the microscope. The paper is printed in full in the Memoirs. Mr. Francis Jones, M.Sc, F.R.S.E., read a paper entitled "The Action of Selenium and Tellurium on Arsine and Stibine," which is printed in full in the Memoirs. XX Proceedings. [JArrr// 24.111, igoS. Ordinary Meeting, March 24th, 1908. Professor H. B. Dixon, M.A., F R.S., President, in the Chair. The thanks of the members were voted to the donors of the books upon the table. Mr. G. A. Dun LOP read a paper (communicated by Mr. T. A. Coward, F.Z.S.), entitled "An Annotated List of the Alien Plants of the Warrington District." The paper will be published in the Memoirs. Mr. T. A. Coward, F.Z.S., read a paper written by Mr. Charles Oldham, F.Z.S., M.B.O.U., entitled "Field Notes on the Birds of the Ravenglass Gullery, 1906." The author described in his paper the habits, during the breeding season, of the Black-headed Gull, Common, Lesser, and Sandwich Terns, as observed by him at Ravenglass, on the Cumberland Coast. The term " gullery " he applied to that portion of the sandhills which is occupied by colonies of these birds. He also mentioned other species — such as the Oyster- catcher and Sheld-duck — which nest in or in the immediate vicinity of the "gullery." He referred to the change in the vegetation of the sandhills, caused by the presence of the unusual number of birds, and also drew special attention to a habit of the young Sandwich Tern, which obtains concealment from enemies by partially burying itself in the sand. Ordinary Meeting, April 7th, 1908. Mr. Francis Jones, M.Sc, F.RS.E., Vice-President, in the Chair. The thanks of the members were voted to the donors of the books upon the table. April '/t/i,igoS.] Proceedings. xxi Mr. R. L. Taylor, F.C.S., communicated a paper by Mr. Robert Pettigrew, entitled "On the Occurrence of Quartz Crystals in Limestone, Columnar Coal, Marble, &c." Photographs, microscopic and lantern slides were exhibited, showing beautiful microscopic crystals of quartz obtained from mountain limestone, columnar coal from Airdrie, in Lanark- shire, and ordinary statuary marble. Attention has been pre- viously drawn to the occurrence of these crystals in limestone and marble,* but most of the members of the Society present had not had an opportunity of seeing them. The crystals from limestone and marble are obtained by dissolving some quantity of the material in hydrochloric acid and treating the insoluble portion with strong sulphuric acid and a little potassium chlorate to destroy the organic matter, and then mounting in the usual way. The columnar coal, from which some of the specimens were obtained, resembles in some respects a well-burned coke. It comes from Airdrie, in Lanark- shire, and has been metamorphosed through an intrusive mass of basalt forcing its way along the seam of coal, with the result that the coal has been "coked" to a columnar mass. From this coal the crystals are obtained by grinding it coarsely and washing away the coal. The crystals from both the limestone and the coal are mostly well formed double-ended quartz crystals, in many cases, especially in the smaller crystals, the facets being perfect, as if polished. They vary in size from about yoVsj'^h ^° r^o^h of an inch in length. When mounted in Canada Balsam (which has almost the same refractive index as quartz), a hazy outline only of the crystal is visible, but nearly every crystal shows a dark nucleus on which the crystal has been built. It is Mr. Pettigrew's opinion that this nucleus has been at one time Iron Pyrites, although it is now mostly oxidised to the brown oxide of iron. The crystals in marble, owing to the pressure and meta- * J. Barnes, Trans. Manchester GeoL Soc, vol. 27, part 15. xxii Proceedings. [April yth, igo8. morphosis in the transformation to marble, are rarely perfect, but generally occur as cleavage plates, due to shearing. Many of the crystals appear to have split up, and look almost like cross sections, being hexagonal. Mr. Pettigrew has also found an insoluble residue when clear crystallised calcite or calc spar from Derbyshire is dissolved in hydrochloric acid. This residue consists of pyrites and of quartz, with moulds or hollows showing where the pyrites have been imbedded. The quartz crystals are cubic, and show in most cases exact counterparts of pyrites crystals, proving them to be pseudomorphs, after pyrites. This shows, of course, that the pyrites crystals were formed first, and that the silica is due to a secondary process of crystallisation by replacement. Professor Edmund Knecht, Ph.D., M.Sc.Tech., F.I.C., read the following paper, entitled " Note on the Action of Oxalic Acid on Cellulose. " Although oxalic acid has been used in calico printing for a very long time, it has not until comparatively recently been supposed to exert an influence upon cellulose difl'erent to that of any other acid of similar strength. In 1902, however, there appeared in The Dyer and Calico Printer an anonymous article (which I have since ascertained was written by one of my former students, Mr. H. H. Pilkington), in which it is pointed out that if calico is printed with thickened oxalic acid, and is then allowed to dry in a cool place for twelve hours, and subsequently washed, the printed parts show an increased affinity for basic colours, and a decreased afifinity for so-called direct colours. The cloth is not tendered in the printed places. Citric and tartaric acids do not produce this effect. The author merely recorded these interesting facts, but offered no explanation. In view of these interesting results it appeared to me desirable to attempt to find some explanation of this remarkable behaviour of oxalic acid, and I consequently first repeated the experiments, and was able to verify the results. I found that by boiling the treated fabric first in alcohol, and April yth, igo8?\ Proceedings. xxiii then in ether, the effect could not be removed. By boihng, how- ever, in a dilute solution of caustic soda for a few minutes, all trace of the action of the oxalic acid vanished, without any tendering of the fabric being noticeable. This observation precluded, there- fore, the possibility of the formation of oxycellulose. It almost appeared as if some of the oxalic acid had combined with the cellulose to form an oxalate, which, by analogy with the nitrates, acetates, &c., would show the characteristic behaviour towards dyestufifs. I was unable, however, to detect oxalic acid in the caustic soda extract of the treated fabric, and for some time gave up the work. On resuming my investigation into the subject, I was led to test the caustic soda extract of the treated fabric for formic acid, which was found to be present. It would therefore appear that in drying the oxalic acid had undergone decomposition into carbonic acid and formic acid, which latter had in the nascent state combined with the cellulose. Attempts to determine quantitatively the actual amounts of cellulose formiate produced were not satisfactory, the results obtained being very irregular. In any case, however, the amounts found appear to be only small. This explanation of the action of oxalic acid on cellulose becomes all the more probable from the results of further experiments with malonic acid and hexylmalonic acid, both of which behave like oxalic acid, and this would be expected from their behaviour on heating. In the saponification product from cotton treated with malonic acid, it was possible to detect acetic acid. Succinic acid, on the other hand, does not show any altera- tion in the cellulose, nor does glutaric acid. It would appear, therefore, that the action of oxalic acid on cellulose simply constitutes one example of a general mode of formation of acidyl celluloses. Professor Knecht also exhibited specimens of commercial metallic titanium and commercial silicon. In a dicussion which took place later Mr. Julius Hubner xxiv Proceedings. [April yt/i,igo8. said that, in a paper read before this Society in November last, on " New Reactions for the Characterisation of Mer- cerised Cotton," he pointed out that the action of other salts and acids in the presence of very small quantities of iodine was still under investigation. He had found in the mean- time that characteristic reactions on mercerised cotton were pro- duced by a large number of acids and salts in the presence of iodine. Among others he wished to mention here oxalic acid, citric acid, formic acid, and tartaric acid. With all these acids mercerised cotton exhibited a greater reactivity than did ordinary cotton. Glacial acetic acid was found to be less suited for this purpose. Manchester Memoirs, Vol. Hi. (1908), No. 13. XIII. Report on the Recent Foraminifera from the Coast of the Island of Delos (Grecian Archi- pelago). Part V. By Henry Sidebottom. (Received atid read March loth, igoS.) Uvigerina, d'Orbigny. Uvigerina canariensis, d'Orbigny (PI. i, figs, i, 2). Uvigerina canariensis, d'Orbigny ('39), p. 138, pi. i, figs. 25-27. U. urnula, d'Orbigny ('46), p. 189, pi. ii, figs. 21, 22. U. irregularis, Brady ('65), p. lOO, pi. 12, fig. 5. There is a certain amount of suspicion attached to the identification of these specimens, Very rare. Uvigerina tenuistriata, Reuss (Pi. i, fig. 3). Uvigerina tenuistriata, Reuss ('70), p, 485, — Schlicht ('70), pi. 22, figs. 34, 37. U. temcistriata (Reuss), Brady ('84), p. 574, pi. 74, figs. 4-7. Although not quite typical, the contour of the test is sufficient to bring it under this heading. There are very faint indications on some of the chambers of the striae which are present in the type. Only one was found. *Uvigerina angulosa, Williamson (PI. i, fig. 4). Uvigerina angulosa, Williamson ('58), p. ^7, pi- 5, fig. 140. * The asterisk denotes that this species occurs at Palermo. May 2jrd, igo8. 2 SlDFBOTTCJM, For aniinif era from the Island of Delos. "~ U. trigona, Seguenza ('62), p. no, pi. 2, figs, i, la. U. angulosa (Williamson), Flint ('99), p. 320, pi. 68, fig- 3- The one figured is the most typical of the set. The initial chambers of the Delos specimens have not the angular character of the type, and the minute pores of these chambers are apt to arrange themselves in lines, giving the appearance of minute costs. Very rare. Uvigerina auberiana, d'Orbigny, van glabra, Miilett. (PI. I, figs. 5,6.) Uvigerina auberiana (d'Orb.), var. glabra, Miilett (: 03), p. 268, pl. 5, figs. 8, 9). Mr. Miilett, in the above reference, speaks of this form as being quite smooth, also more compressed and neater than that described by d'Orbigny ('39) from the West Indies. The Delos tests agree with the Malay forms. Some of the elongate examples have as many as eighteen or nineteen chambers, and differ, as Mr. Miilett states, from Bolivina, only in the form of the aperture. Prequent *Uvigerina, sp. (PI. i, fig. 7.) The examples appear to me to be a very weak form •of Uvigerina porrecta, Brady ('84), pl. 74, figs. 21-23. I have examples from Raine Island of the type, and in one of them the costae on the final chamber are faint. In the Delos specimens some of the final chambers show traces of fine striae caused by the coalescing of the pores, also the earlier chambers in some cases have jagged •edges and fine costae. The neck is not so much produced as in Brady's figures, but the everted lip is present in MancJiester Memoirs, Vol. Hi. (1908), No. 13. 3 some cases. A good specimen from Delos laid alongside a not very well-developed one from Raine Island, shews great similarity in many respects. It may be a passage form in the direction of Sagrina nodosa., P. & J., but I have not come across a single Sagrina of any description in the Delos dredgings. Rather rare. GLOBIGERINIDtE. Globigerina, d'Orbigny. *Globigerina bulloides, d'Orbigny. Globigerina bulloides, d'Orbigny ('39), p. 132, pi. 2, figs. 1-3. G. bulloides, d'Orbigny ('46), p. 163, pi. 9, figs. 4-6. G. bulloides (d'Orb.), Terquem (^'75), p. 31, pi. 4, figs. 5, «, ^. G. bulloides (d'Orb.), Brady ('84), p. 593, pi. 79, figs. 3-7. G. bulloides (d'Orb.), Silvestri ('98), p. 245, pi. 4, figs. 7-9. Occurs in two forms, one of which is smaller, more transparent, and much more planospiral than the other. *Globigerina triloba, Reuss. (PI. i, fig. 8.) Globigerina triloba, Reuss ('50), p. 374, pi. 47, fig. 11. G. triloba (Reuss), Terrigi ('80), p. 188, pi. i, fig. 18. G. bidloides, var. triloba (Reuss), Brady ('84), p. 595, pi. 79, figs. I, 2, and pi. 81, figs. 2, 3. I very much doubt if this form should be treated as a " species," or, rather, as the immature condition of some other species of Globigerinae. Very rare. 4 SiDEBOTTOM, Foraniinifera from the Island of Delos. *Globigerina rubra, d'Orbigny. Globigerina rubra, d'Orbigny ('39), p. 82, pi. 4, figs. 12-14. G. rubra (d'Orb.), Brady ('84), p. 602, pi. 79, figs. 1 1-16. G. rubra fd'Orb.), Fornasini ('99), p. 580, pi. 2, fig. 11. G. rubra (d'Orb.), Silvestri ('98), p. 262, pi 5, fig. 4. Most of the specimens are of the usual rosy-pink colour. Several have a glassy appearance, the typical colour being absent. I do not think these latter can be a distinct species, as in one instance the earlier chambers shew traces of colour. The spire varies very much in height. In these gatherings this species is far more numerous than any of the Globigerinidae. Frequent. Globigerina aequilateralis, Brady. (PI. i, fig. 10.) Globigerina aequilateralis, Brady ('84), P- 605, pi, 80, figs. 18-21. G. aequilateralis (Brady), Silvestri (98), P-265, pi. 5, fig. 8. G. aequilateralis (Brady), Fornasini ('99). p. 580, pi. 4, figs. 3> 4- G. (Equilateralis (BradyJ, Flint ('99), p. 323, pi. 70, fig- 3- One or two of the examples found bear short blunt spines, and these are in a more recent condition than the others. Very rare. Globigerina helicina, d'Orbigny. (PL i, fig. 9.) Globigerina helicina (d'Orb.), Brady ('84), p. 605, pi. 2>i, figs. 4, 5. G. helicina (d'Orb.), Silvestri ('98), p. 264, pi. 5, fig. 6. G. helicina (d'Orb.), P'ornasini ("99), p. 583, pi. 3, figs, II, 12. MancJiester Memoirs, Vol. Hi. (1908), No. IJ{. 5 G. helicina (d'Orb.), Millett (-.03) p. 688, pi. 7, fig. i. A single specimen, and typical, occurs. It is always reported as a rarity. Brady, in the Challenger report ('84), p. 605, writes of its being found in the Mediterranean, giving Soldani as his authority. I have a typical example also from the coast of the Island of Rhodes, in which the central portion of the test is rosy-pink ; this specimen is apparently a variety of G. rubra. Orbulina, d'Orbigny. *Orbulina universa, d'Orbigny. Orbulina universa, d'Orbigny ('39), p. 3, pi. i, fig. I. O. universa (d'Orb.), Brady ('84), p. 608, pi. 78, pi. 81, figs. 8-26, and pi. 82, figs. 1-3. O. universa (d'Orb.), Brady, Parker and Jones ('88), p. 225, pi. 45, figs. 7, 8, 14. O. universa (d'Orb.), Silvestri ('98), p. 266, pi. 5, figs. 1 1 -16. O. universa (d'Orb.), Flint ('99), p. 323, pi. 69, fig. i. This elegant foraminifer is rather rare in these gather- ings, and calls for no remark, except that they are in good condition and of fair size. Sphaeroidina, d'Orbigny. Sphaeroidina bulloides, d'Orbigny. (PI. i, fig. 11). Sphceroidina austriaca, d'Orbigny ('46), p. 284, pi, 20, figs. 19-21. 5. bulloides (d'Orb.), Brady ('84), p. 620, pi. 84, figs. 1-7- 5. bulloides (d'Orb.), Goes ('94), p. 87, pi. 14, fig. 770. 5. bidloides (d'Orb.), Flint ('99), p. 325, pi. 71, fig. i. Only a single specimen was found. The test is nearly spherical, and the surface polished. This fora- minifer is rather frequent off the island of Rhodes. 6 SiDEBOTTOM, Foraviinif era from the Islattd of Delos. ROTALID^. SPIRILLININyE. Spirillina, Ehrenberg. *Spirillina vivipara, Ehrenberg, and varieties (Fl. i, figs. 12-14, and PI. 2, figs. I — 3). Cor'nuspira perforata, Schultze ('54), p. 41, pi. 2, fig. 22. Spirillina perforata, Williamson ('58), p. 92, pi. 7, fig. 202. 5". vivipara (Ehrenberg), Parker and Jones ('65), p' 397, pi. IS, fig. 28. 5. perforata (Schultze), Terquem ('75)? P- 21, pi. i, fig- 5- Spirillina vivipara occurs in several forms, and as the variations are slight I have brought them together under the above heading. *Fig. 12, PI. I, is more concave on the inferior surface than on the superior. The pores on the latter are very- numerous and often coalesce at their edges owing to shell growth, producing a "sandy" effect, which might be mis- taken for minute tubercles in some instances, but the tests do not bear the same character as Brady's ^. tiiberculata of the Challenger report ('84). The pores do not show on the inferior surface. Rare. *Fig. 13, PI. I, is distinctly perforated ; concave on the superior side, and flat on the inferior. The perforations shew on the inferior surface, but are not quite so obvious as those on the upper side. All the tests appear to be in the megalospheric condition. Rare. Fig. 14, PI. I. This variety is concave on both its surfaces. It has a still more sandy appearance on its superior face than Fig. 12, and from the same cause. The inferior surface is decorated with bars, which as they Manchester Memoirs, Vol. Hi. (1908), No. 13. 7 approach the centre of the test assume the form of tubercles. It is still more concave than the upper side. Rare. *Fig. I, PI. 2. This variety has the superior surface of the test very much crinkled, and either flat or very slightly concave. The inferior side is distinctly per- forated. Rather frequent. Fig. 2, PI. 2. A single example only was found, which I think may be brought under this designation. Its peripheral edge is rounded, the chambers are slightly embracing, and the underside of the test is free from markings. It is possible that this specimen may be identical, or nearly so, with the shell figured in the mono- graph of the Crag, by Jones and others ('66 — '97), pi. 6, fig. 22, under the name of 5. vivipara, Ehrenberg, var. minima, Schacko (var. iinilinearis, nov., in the explanation of the plate). There is a certain amount of shell growth running along the inner edge of the coil, which interferes with the clear examination of the markings. When damped these markings appear to me to partake more of the nature of ridges than of the coarse perforations which are distinctive of var. minima. My drawing of this example had better, therefore, be taken with a certain amount of reservation. Fig. 3, PI. 2. Another solitary example was found suffering from the same obscuration of the markings as the one above, and when damped it seemed to reveal the same ridge-like markings. The test is very concave on the upper surface, and flat on the lower one. Its upper edge is rounded and its side oblique. It is possible that this is a passage form, in the direction of S. incEqualis Brady ('84). Tests of a similar contour, but without the markings, occur off Raine Island, Challenger Station, 185. 8 SiDEBOTTOM, Foraiiiinifera from the Island of Dclos. Spirillina vivipara, Ehrenberg, var. carinata, Halkyard. (PL 2, fig. 4.) Spirillina vivipara, Ehrenberg, var. carinata, Halk- yard ('89), p. 69, pi. 2, fig. 6. Mr. Halkyard's description of this variety runs as follows : " It differs from the type species in having the periphery carinated, though the keel is not entire, but irregularly crenated. This, however, may be caused by accidental fracture. The tube is not closely coiled, but each convolution is applied to the carina of the previous one, the carina being repaired and strengthened so that it is now entire." Mr. Halkyard found it at St. Brelade's Bay, in Jersey, one of the Channel Islands. The Delos specimens, four in number, are identical with the one figured by Mr. Halkyard in the above reference. Very rare. Spirillina vivipara, Ehrenberg, var. complanata, Jones and others, var. (PI. 2, fig. 5). Spirillina vivipara, Ehrenberg, var. complanata,' ]ox\cs, and others ('96), p. 290, pi. 3, figs. 20-22. Unfortunately I lost this specimen before the com- pletion of the drawings. Mr. Millett, however, had seen it, and considered it to be near to the " Crag" specimen referred to above. Spirillina decorata, Brady, var. (PL 2, fig. 6). Spirillina decorata, Brady ('84), p. 633, pi. 85, figs. 22-25. One example only was found ; it answers fairly well to Brady's description of 6". decorata, excepting that the peripheral edge is serrate. I have found this serrate variety in material from the Challenger Station, 185, off Raine Island, the test being minute, as is the case with Manchester Memoirs, Vol. Hi. (1908), No. 13. 9 the Delos specimen, but the markings more typical. Mr. Chapman figures a somewhat similar shell under the name of .S. spiuigera, from the lagoon of Funafuti (:0l). Spirillina ornata, n. sp. (PI. 2, figs. 7, 8). The test is in the form of a very much depressed cone. The outside edge of the coil on the superior surface slightly overlaps, and appears to be in-the nature of a keel, and is decorated with minute raised ridges, except in the final convolution. The under surface of the test is flat, and sealed up with exogenous shell- deposit. The specimens are semi-opaque, and of a pale milky-yellow colour. The peripheral edge is more or less sinuous, unless this is due to fracture. Spirillina lucida, n. sp. (PI. 2, fig. 9). The test consists of about six convolutions, of which only two or three are visible on the inferior surface. The umbilical cavity is deeply sunk, and appears to me to be slightly twisted. The perforations are very minute, and the shell is convex on the upper surface. The peripheral edge is sharp, and I have been unable to detect the aperture. Very rare. ROTALIN^. Patellina, Williamson. *Patellina corrugata, Williamson. Patellina corrugata, Williamson ('58), p. 46, pi. 3, figs. 86-89. P. corrugata (Williamson), Carpenter ('62), p. 230, pi. 13, figs. 16, 17. P. corrugata (Williamson), Brady ('84), p. 634, pi. 86, figs. 1-7. 10 SiDEBOTTOM, Foraminifera from the Island of Delos. Good specimens occur. The height of the spire varies considerably. Rare. *Cymbalopora, Hagenow. Cymbalopora poeyi, d'Orbigny, sp. Rosalina poeyi, d'Orbigny (.'39J, p. 92, pi. 3, figs. 18-20. Cymbalopora ( Rosalina ) poeyi {d'Orh.), Carpenter ('62), p. 215, pi. 13, figs. 10-12. C. poeyi (d'Orb.), Brady ('84), p. 636, pi. 102, fig. 13, and var. fig. 14. The one specimen found agrees best with the variety figured by Brady ('84), pi. 102, fig. 14. This variety is not at all rare off the island of Rhodes. Cymbalopora bulloides, d'Orbigny. Rosalina bulloides, d'Orbigny ('39), p. 98, pi. 3, figs. 2-5. Cymbalopora bulloides (d'Orb.), Brady ('84), p- 638, pi. 102, figs. 7-12. C bulloides (d'Orb.), Earland (:o2), p. 309, pi. 16, figs. 1-6. C bulloides (d'Orb.), Millett (:03), p. 697, pi. 7, fig. 4. Two examples of this interesting form were found. Mr. Earland, in the above reference, calls attention to the existence of two varieties in this species, viz , the acervu- line and the discorbine. The Delos tests belong to the latter one. The specimens have the "balloon" chamber smooth, and very transparent, the entosolenian "tube" being clearly seen. Mr. Millett, in his Malay report, refers to a variety of this species which has the " balloon " chamber much crinkled. I have this variety from Mahe harbour, Seychelles Islands, 14 fathoms. Manchester Memoirs, Vol. Hi. (1908), No. IS. 1 1 Discorbina, Parker and Jones. Discorbina turbo, d'Orbi^^ny, sp, (PI. 3, figs, i, 2). Rotalia {TrocJmlind) turbo (d'Orb.), Parker, Jones, and Brady ('65^ p. 30, pi. 2, fig. 68. The tests are stoutly built, and coarsely perforated both on the superior and inferior surfaces. The sutures are marked by lines of clear shell-substance, varying in width. The height of the spire varies, and the peripheral edge is generally slightly lobulated. If I am right in the diagnosis of these specimens, it is interesting to find them in such comparative abundance ; Discorbina turbo being considered rare in the recent condition. Very frequent. *Discorbina globularis, d'Orbigny, sp. and varieties. (PL 3, figs. 3-8, and pi. 4, figs, i, 2.) Rosalina variaus, Schultze ('54), p. 60, pi. 3, figs. 8-13. R. globularis (d'Orb.), Parker, Jones, and Brady ('65), p. 30, pi. 2, fig. 69. R. globularis (d'Orb.), Terquem ('78), p. 25, pi. 2 (7), fig. 10. Discorbina globularis (d'Orb.), Brady ('84), p. 643, pi. 86, figs. 8, 13. D. globularis (d'Orb.), Brady, Parker, and Jones ('88), p. 226, pi. 46, fig. 6. The examples of this common species, shew a very wide range of variation. The type-form is fairly frequent, but the large flat ones similar to Fig. 5, PI. 3 (*), and the rugose ones. Fig. 6, PI. 3 (*), are very common. The rugosity is caused by the growth of the edges of the pores which coalesce, and in some cases this deposit is so thick as to obscure the segmentation of the test. Forms like Fig. 8, PI. 3, and Fig. i, PI. 4 (*), are limbate, and 12 SiDEBOTTOM, ForaiiiiiiifeTa froiu the Island of Delos. some of them appear to me to be near Rosalina {Dis- corbind) binkhorsti Reuss ('6l), and Discorbina valvtdata^ d'Orbigny ('39). These occur frequently. Complanate specimens, Fig. 2, PI. 4, approach the Rosalina (^Dis- corbina) cava, d'Orbigny ('39), and are frequent. Discorbina rosacea, d'Orbigny, sp. (PI. 4, figs. 3, 4, 5). Rotalina inauiilla, WiUiamson ('58), p. 54, pi. 4, figs. IO9-111. Rotalia rosacea (d'Orb.), Parker, Jones, and Brady ('65), p. 25, pi. 2, fig. 71. Discorbina rosacea (d'Orb.), Brady ('84). p- 644, pi. 87. figs. I, 4. D. rosacea (d'Orb.), Flint ('99), p. 327, pi. 72, fig. 3. This is present in two forms, one of which, Figs. 3, 4, PI. 4 (*) is very large, the test rather complanate, and of a rich brown colour. The perforations are much more numerous on the inferior surface. Very frequent. The other form. Fig. 5, PI. 4, is not nearly so large, and the test is almost free from colour. A single row of con- spicuous perforations decorate each chamber close to the outside edge. I have specimens identical with these from Bantry Bay, Ireland. Rather rare. Discorbina araucana, d'Orbigny. Rosalina arancana, d'Orbigny ('39), p. 44, pi. 6, figs. 16- iS. Specimens occur which may be placed under this heading, but they are not typical. Very rare. Discorbina vilardeboana, d'Orbigny, sp. Rosalina vilardeboana, d'Orbigny ('39), p. 44, pi- 6, figs. 13-15. Manchester Memoirs, Vol. Hi. (1908), No. 13. 13 The above remarks apply also to this form, except that this latter one is very frequent. Discorbina nitida, Williamson. (PI. 4, fig. 6). Rotalina nitida, Williamson ('58), p. 54, pi. 4. figs. 106-108. R. nitida (Williamson), Terquem ('75), p. 26, pi. 2, fig. 9. There are very fine examples of this transparent and complanate Discorbina. The sutures are marked by fine lines, and the outside edge of the chambers in the later whorls is flattened. The largest specimens shew only three chambers in the final convolution. Rather rare. *Discorbina orbicularis, Terquem, sp. (PI. 4, fig. 7). Rosalina orbicularis, Terquem ('75), P- 75, pl- 9, fig- 4- Discorbina orbicularis (Terquem), Balkvvill and Wright ('85), P- 349, pl- 13, figs- 3 1-33- D. orbicularis (Terquem), Brady ('84), P- 647, pl. 88, figs. 4-8. The tests are typical, and in some of the larger examples the limbation is well marked. Rather rare. Discorbina imperatoria, d'Orbigny, sp. (Pl. 5, figs, i, 2.) Rosalina imperatoria, d'Orbigny ('46), p. 176, pl. 10, figs. 16-18. The specimens answer in their salient points to d'Orbigny's description of the species, which, as far as I am aware, has not been found before in the recent condition. D'Orbigny's examples were from the Tertiary of Tarnapol, Galicia, and stated to be rare. The Delos tests differ from d'Orbigny's drawings in having the chambers of the last convolution slightly inflated, and more erect. The pores are prominent, and 14 SiDEBOTTOM, Forauiinifera from the Island of D do s. cause the test to be rugose. Along the sutural lines the pores hardly show, and so the tests have a more or less striped appearance. A good deal of exogenous shell growth is present in the umbilical region of the larger specimens, the inferior surface being decorated with radiating lines of minute tubercles. Rather frequent. Mr. Millett figures a variety of D. iinperatoria in his Malay report (:03), pi. 7, fig. 6, under the name of Z>/.y- corbiua iinperatoria, d'Orb., var. g/obosa. Discorbina patelliformis, Brady. (PI. 5, fig. 3.) Discorbina patelliformis, Brady ('84), p. 647, pi. 88, fig. 3 and pi. 89, fig. I. D. patelliformis (Brady), Egger ('93), p. 390, pi. 15, figs. 48-50. Two of the specimens are particularly elegant ; they are the largest of those found, and have the chambers of the last two whorls inflated, the peripheral outline being much lobulated, and the pores more marked. Very rare. Discorbina pulvinata, Brady. (PI. 5, fig. 4). Discorbina pulvijiata, Brady ('84), p. 650, pl. 88, fig. 10. D. pulvinata (Brady), Egger ('93), p. 391, pl. 15, figs. 33~35- Brady, in his provisional description of this species, puts the number of chambers in the last convolution at about three. The Delos specimens have five, with the exception of two or three, which have six. I have speci- mens also from off the island of Rhodes. Very frequent. A variety occurs which has only three or four chambers in the last convolution, these latter are not nearly so compressed, and the chambers on the superior surface are difficult to distinguish owing to exuberant shell growth. In colour they are white. Very rare. Manchester Memoirs, Vol. Hi. (1908), No. IJ5. 15 Discorbina pileolus, d'Orbigny, sp. Vahiilina pileolus, d'Orbigny ('39), p. 47, pi. i, figs. 15-17. Discorbina pileolus (d'Orb.), Brady ('84), p. 649, pi. 89, figs. 2-4. Unfortunately the six tests found are in the condition known as plastogamy, thus forming three pair. I think there can be little doubt that they belong to this species, though not quite typical. In two of them, how- ever, a small portion of the inferior surfaces can be seen (the tests not being of quite the same size), and they appear to bear the characteristic markings. *Discorbina tabernacularis, Brady. Discorbina tabernacularis, Brady ('84), p. 648, pi. 89, figs. 5-7. D. tabernacularis (Brady), Egger ('93), p. 390, pi. 15, figs. 58-60, 79. The Delos specimens agree best with the smaller of those figured by Brady in the above reference, viz., fig. 7, with the exception that the delicate striae are absent. Mr. Millett (:03) reports it from the Malay Archi- pelago, page 700. Very rare. *Discorbina tuberculata, Balkwill and Wright. (PI- 5, fig. 5). Discorbina tuberculata, Balkwill and Wright ('85), p. 350, pi. 13, figs. 28-30. D. tuberculata (B. & W.), Halkyard ('89), p. 70, pi. 2, fig. 10. The tubercles are not so large as those on the speci- men figured by Messrs. Balkwill and Wright, otherwise the specimens are typical. Rather rare. 1 6 SiDEBOTTOM, Forauiinif era from tJie Island of Delos. Discorbina erecta, n. sp. (PI. 5, figs. 6, 7). Test free ; the contour is that of a tall cone, armed with a short spine at the apex. The segments are inflated, and very rugose, and arranged in about six convolutions, the final whorl consisting of about six segments. The sutural lines are wide and sunk. The inferior surface is more or less rounded, and ornamented by radiating rib- lets or granulose lines. The umbilicus is deeply sunk. The tests vary in the height of the spire and amount of rugosity. In some few of the smaller, and presumably younger tests, some of the segments are armed with a small spine. Most probably the extreme rugosity of the larger tests is the result of age. The majority of the specimens are of a greyish-white colour, but a few are tino-ed with brown. Frequent. This species occurs also off the island of Rhodes. Discorbina elegantissima, n. sp. (PI. 5, fig. 8.) The test is composed (in the specimen figured) of fully three convolutions, the final whorl consisting of four seo"ments, which are more outspread than the others. The segments are inflated, the earlier ones short, and the later ones long and arched. The test is opaque (except the last one or two chambers, which are semi-opaque), and the colour a light yellow-brown ; it is also rugose. Six examples of this interesting and handsome foraminifer were found. The one figured is much the largest of the set. The superior surface has a sugary look, and the chambers are lobulated, and the sutures deeply sunk. The inferior surface is slightly convex, and ornamented with radiating lines of minute tubercles. The umbilical region is sunk and obscured by the shell growth. In the example figured, the last convolution is more outspread than in the other ones. Manchesler Memoirs, Vo/ /h'. {igo8), No. 13. 1/ BIBLIOGRAPHY. Balkwill, F. p. and J. Wright ('85). "Report on some Recent Foraminifera found off the Coast of Dublin and in the Irish Sea." Trans. R. Irish Acad., vol. 28, Science, pp. 317- — 372, 3 pis. and figs, in text, 1885. Brady, H. B. ('67). " A Catalogue of the Recent Foraminifera of Northumberland and Durham." Nat. Hist. Trans, Northin.b. and Durham, vol. i, pp. 83-107, pi. 12, 1865 (1867). ('84). "Report on the Foraminifera collected by H. M.S. 'Challenger' during the years 1873-76." Zool. Cliall. Exp., vol. 9, 814 pp., 115 pis., 1884. Brady, H. B., W. K. Parker, and T. R. Jones ('88). " On some Foraminifera from the Abrohlos Bank." Trans. Zool. Soc, vol. 12, pt. 7, pp. 211-239, pis. 40-46 and chart, 1888. Carpenter, W. B., W. K. Parker, and T. R. Jones ('62). " Introduction to the Study of the Foraminifera." Ray. Society, 319 pp., 22 pis., 1862. Chapman, F. (:oi) " Foraminifera from the Lagoon at Funafuti." Linn. Soc. Joicrfi. {Zool.), vol 28, pp. 161-210, 2 pis., 1 90 1. Earland, a. (:02). "On Cymbaiopora Inilloides (d'Orbigny) and its internal Structures." Journ. Quekett Aficro. Club, [2], vol. 8, pp. 309-322, pi. 16, figs. 1-6. Egger, J. G. ('93). " Foraminiferen aus Meeresgrundproben, gelothet von 1874 bis 1876 von S. M. Sch. 'Gazelle.'" Abhandl. k. Bayer. Akad. Wiss., cl. 2, vol. 18, part 2, PP- 193-458, 21 pis., 1893. Flint, J. AI. ('99). " Recent Foraminifera, a descriptive catalogue of specimens dredged by the U.S. Fish Com- mission, steamer 'Albatross.'" Rep. U.S. Nat. Mus., pp. 249-349, 80 pis., 1897. 1 8 SiDEBOTTOM, Foraniinifera from the Island of Delos. FoRNASiNi, C. ('99). "Globigerine Adriatiche." Mem. R. Accad. Sci. 1st. Bologna, [5], vol. 7, pp. 575-586, 4 pis. Goes, A. ('94). "A synopsis of the Arctic and Scandinavian Recent Marine Foraminifera hitherto discovered." K. Svenska. Vetensk.-Akad. Handl. Stockholm, vol. 25, No. 9, 127 pp., 25 pis., 1894. Halkvard, E. H. ('89). "Recent Foiaminifera of Jersey." Trans, and An?t. Rept. Manchester Micr. 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Page I, 2. Uvigerina canariensts, d'Orbigny X 75 I 3- „ tenuistriata, Reuss X 25 I 4- ,, anguiosa, Williamson X 75 I 5,6. „ auberiana, d'Orbigny, var. glabra, Millett X 75 2 7- Uvigerina, sp. X 75 2 8. Globigerina triloba, Reuss X 50 •• 5 9- „ helicina, d'Orbigny X 50 .. 4 10. „ cBquilateralis, Brady X 50 .. 4 II. Sphceroidina bulloides, d'Orbigny X 50 •• 5 12-14. Spirilli?ia vivipara, Ehrenberg and varieties X 75 .. 6 Manchester Memoirs, Vol. LIT. {No. 13). 3 Plate I. 11 13a 14« ■i f B. SMi'bnttnm, cJp?. ad not Foraminifera from the coast of the island of Delos. 22 SiDEBOTTOM, Formumifera froiu the Island of Delos. Plate II. Figs. Page. I — 3. Spirillina vivipara, Ehrenberg, varieties x 75 ... 6 4. „ vivipara, Ehrenberg, var. carinafa, Halkyard x 75 ... 8 5. ,, vivipara, Ehrenberg, vaf. com- />/a«rt/'a, Jones and others, var. x 50 ... 8 6. . ,, decorata, Brady, var. x 75 ... 8 7, 8. „ ornata, n. sp. x 75 ... g 9. „ lucida, n. sp. x 75 ... g Manchestci' Memoirs, Vol. LII. {No. 13). Plate IL 3a 5a 9a H, Sidebottom, dd. cid urit. Foraminifera from the coast of the island of Delos. 24 SiDEBOTTOM, Foraniiiiifera frovi the Islaiid of Delos. Plate III. Figs. Page. I, 2. Discorbina turbo, d'Orbigny, sp. x 50 ... ii 3, 4. „ giobularis, d'Orbigny, sp. X50 ... n 5-7- :, >. .. X25 ••• II 8. „ „ „ X50 ... II Manchester Memoirs, Vol. LII. (No. l:j). Plate III. tia 8a //. .Siilcbutloiii, iM.