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Rtn Macht a as an ha@a 6 awit eee . +4 : Sa ih 4d anary Mons ee AR RA eR cant 9) SAN te asthe Ay, eit 2 FOO a OH OA AA tet ae 4: eR We eet deie hese d eee abi oes oaare Ry detne “ Tie saeAA Daily ‘ ; ’ ue 644 4am 4 Pardee s dee Oras Pe oe eee oe Cc ee ot ot lea et aad 8 tA eh OW Ode He neh Sor et LGA oes 54) Kar ae 9 Sete es veers Ge ; Soak ariatan a4 asec soli nn Waisted area 98 - 74.4 “te aan * ’ ire i+ s id rnd 44 4 ye en eae AAA Aa Peeks Si eset MS crdrelviyr ee ee er ee er ee oo eo ee ee ee 2 be AA Le ee EW Fade Bt eae He et et Bel tel em Oh er tee oe (oWade § ek oe Dek EW dete ew Weds ew FM de ie baie Sia RNS Bee Re ek aed ae et EY Ree ee te ee ee ee ee a4 PAA ab a ac Does ar Da opbieiysuiys, barbed vipa} EL ty wah SEAS c, bi, Cie Ae ete dt rte ee “ ey Braces Aha keith a teas ork Se = Meat Pcs cab PED Ol a aoe Pe a ys AY Aten ere ADT PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON. From November 17, 1881, to March 30, 1882. VOL. XXXITI. (1166 6 3% **eeseee LONDON: HARRISON AND SONS, ST. MARTIN’S LANE, Qrinters in Ordinary to Her Majesty. MDCCCLXXXII. LONDON: HARRISON aND SONS, PRINTERS IN ORDINARY TO HER MAJESTY, ST. MARTIN'S LANE. CONTENTS. VOL. XXX. — £864 — No. 216.— November 17, 1881. Preliminary Notes on the Photographic Spectrum of Comet 6 1881. By wabomebucoms, D.C... LL.D. FBS. (Plate 1).....:.0....0.5 sesccscsconeersoess Note on the Reversal of the Spectrum of Cyanogen. ByG. D. Liveing, M.A., F.RS., Professor of Chemistry, and J. Dewar, M.A., F.RB.S., Jacksonian Professor, University of Cambridge .............:sccccecescesseseseseees The Sums of the Series of the Reciprocals of the Prime Numbers and of puetepeomers by CO. W.. Merrifield, FSR.S:.....ics..csss-0s-s000ssscesc den seherbedsossects Further Note on the Minute sliaena of the 2 ens eu Herbert Watney, M.A., M.D. Cantab.. i astaraecsrosetisoasseects Experimental Researches en the eee of Heat by Conduction in Bone, Brain-tissue, and Skin. By J. S. Lombard, M.D., formerly Assistant Professor ef Physiology in Harvard University.................ese On the Comparative Dumuchure ef the Brain in Rodents. By W. Bevan Lewis, L.R.C.P. (Lond.), Senior Assistant Medical Officer to the West Riding Asylum, Wakefield .. Lotisee Nats Sr cStua uel tinsnaasitsucsontepetatesecadbresete On the Production of Transient Electric Currents in Iron and Steel Con- ductors by Twisting them when Magnetised or by Magnetising them when Twisted. By J. A. Ewing, B. Se., F.R.S.E., Prefessor of Mecha- nical Engineering in the University of Tokio, J apan iectinaee coosasu sees disenoesraee The Prehensores ef Male Butterflies cf the Genera Or ey © and Papilio. By Philip Henry Gosse, FLRAG......c.sscecsscsere-ee Bs On the Propagation of Inhibitery Excitation in the Medulla Oblongata. By Dr. H. Kronecker and Mr. 8. Meltzer, Candidate in Medicine, On the Refraction of Plane Polarised Light at the Surface of a Uniaxal Crystal. By R. T. Glazebrook, M.A., Fellow and Assistant Lecturer of Trinity College, Demonstrator in the Cavendish Laboratory, Cam- ipa ene Maio bc ccasaiis sax adab odeldacanpesp cannon det atemtucemt acess pleosasbenia On Allotropic or Active Nitrogen and on the Complete Synthesis of Am- monia. By George Stillingfleet Johnson, King’s College oe eeeees Page Ut il 15 21 23 27 30) 1V Page Researches on’ Chemical Equivalence. Part IV. Manganous and Nickelous Sulphates. By Edmund J. Mills, D.Sc., F.R.S., and J. H. HIG OU a ces Sans stoctecccauevsdeecoxss dadleoeeetbeates tocar mee eeepc eter tatssc ee. tr 32 Researches on Chemical eaves Part V. By Edmund J. Mills, DeSe SRARSS., amd: Bertram TE toes ocr- nse o ences eonsecen- ce se 32 November 24, 1881. THe BakeriaN Lecture.—Action of Free Molecules on Radiant Heat, and its Conversion thereby into Sound. By Dr. Tyndall, F.R.S.. ....... 33 November 30, 1881. ANNIVERSARY MEETING. Report of Aud rtors -2igseccecaleclsdecscesecceen! ocesseeceuss eeectenessc eee ee 39 List of Fellows deceased since Iast Anniversary — .........csccsssssescesesssecees seeeeees 39 C]eChed © koe ceccccse cococoeorgecedecncns ecsentesccscnaencss/leee ee on es Address. of. the..President....c..ccscsevehsseterssevetale ectsintan we 40 Presentation of the Medals .........24.c0ccccxtsicetcde Oe eee 65 Election of Council and Officers 05.0 iio ceccsccessseeede cence 67 Financial Statement sidhtivsuiewictna line re APSE EUS 2..2<250000scansndoesscadeastoaeaeeatsecbieuscececkeae nce. oa (Pas Account of the Appropriation of the sum of £1,000 (the Government Grant) annually voted by Parliament to the Royal Society, to be employed in aiding the advancement of Science ...cc.cccscccesssssssseessseeeeeeees 76 Account of Appropriations from the Government Fund of £4,000 made by the Lords of the Committee of Council on Education, on the recom- mendation of the Council of the Royal Society ............... bet saivet eee 77 Report of the Kew Committee: v1.0) 222i econ neon 80 Thist Of Presemtsicccs.scssiescss.cacesecebesiaschece corse eaeeeeessethon.tees ok eee 100 No. 217.—December 8, 1881. On the Genus Culeolus. By W. A. Herdman, D.Sc., F.L.S., F.R.S.E., Demonstrator of Zoology mn the University of Edinburgh...............:.c00 104 On the Development of the Skull in ee osseus. By W. K. LEGG) aie tie ats Reaetepeiee ear ebb aid wom hemes te uate asaoscearpaceee cee On On the Structure and Development of Lepidosteus. et EF. M. Balfour, LL.D. WOR.S., and WIN. Parken... .veccscesccssyreceivecees-s4sess 112 On a New Mineral found in the Island of Cyprus. By Paulus F. Bveinsch: (Hrlameen) 10.6.4. Jesiibevesew cc Mlesanssosdeetssaesoeasacdeeteaeetsce a er 119 Vv age On certain Points in the Anatomy of Chiton. By Adam Sedgwick, MEA’ Fellow of Trinity College, Cambridge .............ssemescesssseoseoscsressseeees 121 Beeeerenonm or Cutuime Tools, “By A. Mallochs..........ccccccseccencssssseessenetonsece vans 127 On Seismic Experiments. By John Milne, F.G.S., and Thomas Gray, 52 Sop IEIRGS AIRE. Cecteere Schaal eo A ee 139 On the Electrolytic Diffusion of Liquids. By G. Gore, LL.D., F.R.S. .... 140 On the Coefficients of Contraction and Expansion by Heat of the Iodide of Silver, AgI, the Iodide of Copper, Cu,I,, and of Five Alloys of these Iodides. By G. F. Rodwell, F. RAL S., F.C.S., Science Master in Mima OEE GEIMED (ONES toe rae ce coos occa ccae tas casts sacesevoteys eos cadessnosuessasea? cceuseeveoeates 143 On the Vibrations of a Vortex Ring, and the Action of Two Vortex Rings upon each other. By J. J. Thomson, B.A., Fellow of Trinity ee URN LEV) Cais oc Scale oon Reten econ co eee ken skdnsecevt esontuseodttalonogashscatdestyesesssds 145 Letter addressed to the Secretary R.S. by Dr. W. Roberts, F.R.S. ....... 0... 147 December 15, 1881. On the Electromotive Properties of the Leaf of Dionzea in the Excited and Unexcited States. By J. Burdon Sanderson, M.D., F.R.S., &e. ..... 148 On some Effects of Transmitting Electric Currents through Magnetised peeing, Wr. G. Gores HRS), c...ctsscs.scecesensenesanee-nenotocdzescodeoesbeedace 151 Freliminary Report to the Solar Physics Committee on the Sun-spot Observations made at Kensington. By J. N. Lockyer... 154 Bon G-Lutidine. By C. Greville Williams, FLR.S. wi... cesses essen 159 On the Effect of the Spectrum on the Haloid Salts of Silver, and on Mixtures of the same. By Captain Abney, R.E., FBS. oe 164 On a New Electrical Storage Battery. By Henry Sutton (Ballarat, LES TIEE), cc sescon soc pete aan Eo ne 187 December 22, 1881. On the Germinal Layers and Early Development of the Mole. By (ERT TELE cag AUR ae ee nee eM A 190 On the Rhythm of the Heart of the Frog, and on the Nature of the Action of the Vagus Nerve. By W. H. Gaskell, M.D. Cantab. ............ 199 On Melting Point. By Edmund J. Mills, D.Sc., F.R.S., Young Professor of Technical Chemistry in Anderson’s College, Glasgow.........ccccecssseseeee 203 Memoir on the Theta-Functions, particularly those of Two Variables. By A. R. Forsyth, B.A., Fellow of Trinity College, Cambridge ............ 206 On certain Geometrical Theorems. No.1. By W. H. L. Russell, F.R.S. 211 On a Class of Invariants. By John C. Malet, M.A., Professor of Mathe- Meme INS COMES, “COD iri asiidadesed side cdesosecusatives sho leodetivdcrosenveee sndeete 215 vil Page On the Constituent of the Atmosphere which absorbs Radiant Heat. By S. A. Hill, B.Sc., Meteorological Reporter for the North-Western Provinces and Oudh, India ......ccceceeeeeecseeseseceeeneeecseseseeneseresereesesseneenesees 216 Taist: OF IPreS@mts -.cccssu.cccscseceecesscseran sso nencisaceecsesoneeeac: cast enceneseqe nls ri n77saeueenaneine aeareas 226 On Trichophyton tonsurans (the Fungus of Ringworm). By George Thin, MEDD, (RIB 2) on. cccceccetensecaceceoesseccoessueesnc etesrtesscorsossctconss sossscrsachaleen cease amaraease 234 On Bacterium decalvans : an Organism associated with the Destruction of the Hair in Alopecia areata. By George Thin, M.D. (Plate 3) ........... 247 No. 218.—January 12, 1882. On the Results of Recent Explorations of Erect Trees containing Repti- lian Remains in the Coal Formation of Nova Scotia. By J. W. Dawson, C.M.G., LL.D., F.B.S., GC. ..cccccecssencecererecceesseesceesenazeccssnnsenesneecees 254 On the Variation of the Electric Conductivity of Glass with Temperature, Density, and Chemical Composition. By Thomas Gray, B.Sc., F.R.S.E. 256 On a New Electrical Storage Battery. (Supplementary Note.) By Henry Sutton..........-.ecesesecscscesssssnsccescsssescecencesesesnness seeosrnsacssnsacssenscenereneensntsa=ts 257 January 19, 1882. On certain Definite Integrals. No. 10. By W. H. L. Russell, FLRS. .... 258 Manometric Observations in the Electric Arc. By Professor Dewar, IVA TOS SO si iialiccc ade cenececadenesete ones dhoccuzcrsessesteessccnsecte seine eta eee eam 262 January 26, 1882. On a Series of Salts of a Base containing Chromium and Urea. No. 1. By W. J. Sell, M.A., F.1.C., Demonstrator of Chemistry in the Uni- versity Of Cambridge ...........sscessesscsssnscseeceneccresenessercoesconesreesncssesanssnrasnentenses 267 On the Spectrum of Water. No. II. By G. D. Liveing, M.A., F.RS., Professor of Chemistry, and J. Dewar, M.A., F.R.S., Jacksonian Pro- fessor, University of Cambridge ...............csesccsecsceseceeescsecseseescesecnessnsseaensens 274 An Attempt at a Complete Osteology of Hypsilophodon Foxit, a British - Wealden Dinosaur. By J. W. Hulke, FvRUS. .............2:2----csceserenst sense teueeee 276 The Influence of Stress and Strain on the Action of Physical Forces. By Herbert Tomlinson, BiA..i.s..:.-2:1-:-e-0ae+-scaseoneidsson-ceeuennncet- serieces cena: ae eee Enea 276 Tuist. of Presents ceccodactcsssgie cadens eet he sechbe-pse-- Sodevscacuent actos udch s+ See 285 On the Limit of the Liquid State. By J. B. Hannay, F,R.S.E., &e. ........ 294 February 2, 1882. Sur les Surfaces Homofocales du Second Ordre. By Lieut.-Colonel A. Mannheim, Professor in the Ecole Polytechnique ............4. aBiadd ode Aide 322 Vil On Measuring the relative Thermal Intensity of the Sun, and on a Self- Registering Instrument for that purpose. By E. Frankland, D.C.L., F.R.S SOMO eee ee Hee OER EH RHEE HEH SE ET HEE HEE EEES EES ESEDHSEE HEHE SEES H SHOOT HOSE EEES EEE EH SES EEE EEEE SHES EEE DEEES February 9, 1882. Note on Mr. Russell’s paper, “ On certain Definite Integrals. No. 10.” Ey Wallan Spoutiswoode, M.A., D.C.L., Lu.D.,, Pres. R.S..........-0...-.00- Report of an Examination of the Meteorites of Cranbourne, Australia ; of Rowton, Shropshire; and of Middlesbrough, in Yorkshire. By Walter Flight, D.Sc., F.G.S., of the Department of Mineralogy, British aE MMUMMSIOMERE TLS LCCTISING GON secaccs seccsocovessadsessinersiaictvarecsesensveacousviscareces@sns sete February 16, 1882. On Impact with a Liquid Surface. By A. M. Worthington, M.A............ The Minute Anatomy of the BREE By Herbert Watney, M.A., M.D. ie NDE, re eee Nae treo alec tae ie Seaanstcaielacuaseeves yonpeasecdsevasnenatcs On the Influence of the Galvanic Current on the Excitability of the Motor Nerves of Man. By Augustus Waller, M.D., and A. de Watte- I a hoo cas Seas eu crs whee pis-vode Sorace tauousecncacessdutavargwiadsoneends On the Excretion of Nitrogen by the Skin. By J. Byrne Power, L.C.P.I. February 23, 1882. THE BAKERIAN LecruRE, on the “ Chemical Theory of Gunpowder.” By eee PICS. EMD)! BRS ii cccecascsacaosececesoosseccoessavscneresceesenusenscasasesdee od LE LETRAS GDLGS) ocncosse Recep Rene Rete RES OEE Der rt Ere aCE So Soe Rene PER PSone Risener ae eee No. 219.—March 2, 1882. DUMP earache GES FOr) TSLCCEION \sccsécecessc.osesceosseacsvccsscscbesalavcssssagusoenvacdeesossevseczedt A Contribution to the Pathology of the Epidemic known as the “ Salmon Pisease. By Professor T. H. Huxley, LLD., F.R.S. ........ icone eee On the Conservation of Solar Energy. By C. William Siemens, D.C.L., emits Metis UNS, CH. 2. co.cccceceeccssscodestesseosevscotestsnasesenssancnacensestsaes March 9, 1882. Experiments to Determine the Value of the British Association Unit of Resistance in Absolute Measure. By Lord Rayleigh, F.R.S., Professor of Experimental Physics in the University of Cambridge 0... Contributions to the Anatomy of the Central Nervous System in Verte- brate Animals. Sub-section I. Teleostei. Appendix. On the Brain m@epie Mormyride. By Alfred Sanders, M.R.C.S.........cccssescsscssecssevsoes Page ool 341 343 347 349 309 304 . 361 d71 380 381 389 398 . 400 Vill On the Spectrum of Carbon. By G. D. Liveing, M.A., F.R.S., Professor of Chemistry, and J. Dewar, M.A., F.R.S., Jacksonian Professor, Wniviersity of Camborid ee v.....ciasicccv.evs-ccsces capssseosrcosserssonenest ate eee eee 403 Preliminary Report to the Solar Physics Committee on a Comparison for Two Years between the Diurnal Ranges of Magnetic Declination as recorded at the Kew Observatory, and the Diurnal Ranges of Atmos- pheric Temperature as recorded at the Observatories of Stonyhurst, Kew, and Falmouth. By Balfour Stewart, LL.D., F.R.S., Professor of Physics) at Owens College; Manchester, iis .i5..-c0c--1-+s:ccccs-ae tee see eee 410 March 16, 1882. Sur les. Centres de Courbure Principaux des Surfaces Homofocales du Second Ordre. By Lieut.-Colonel A. Mannheim, Professor in the Heole Polytechmique «.....:2..05s:.t. sacs aoohenactec sede thecue cece cee 421 Note on the Photographic Spectrum of the Great Nebula in Orion. By Wilham Hiugeins, Cl LTD, WR S. cece ccescscesne eae eee eee 425 On the Disappearance of some Spectral Lines and the Variations of Metallic Spectra due to Mixed Vapours. By G. D. Liveing, M.A., F.R.8., Professor of Chemistry, and J. Dewar, M.A., F.BS., Jacksonian Professor, University of Cambridge 0.00... cssscscesseeresceseseoeeee 428 March 23, 1882. On the Constituent of the Atmosphere that Absorbs Radiant Heat. II. By 8. A. Hill, Meteorological oe North-West Provinces and QUID © Lecce discscseisasvccedeRepadsearouccnobes dntakeatqatyodole tleesssesustussscaeeetnstes tease tae eam 435 On the Influence of Coal-dust in Colliery Explosions. No. IV. By W. GaAllOWAY ..evisescisnedecsesosessscveecsesidescnsion touacssenssedocosscsvedes ten: ttetee che eee aan 437 March 30, 1882. On the Development of the Ossicula Auditus in the Higher Mammalia. By Alexander Fraser, M.B., &c., Senior Demonstrator of Anatomy, Owens College, Manchester..............00. u cevuva vudsedseinsedilsegysbdaoseseeee ene Rent oe nea aaa 446 Description of the Fossil Tusk of an extinct Proboscidian Mammal (Wotele- phas australis, Ow.), from Queensland, Australia. By Professor Owen, CIB., FBS... S66. c.csccserecsessassosconsassoecsesccugeseehsteesrsuloer taeteuts aster eee neem . 448 Action of Ethylene Chlorhydrin upon the Bases of the Pyridine Series and on Quinoline. By Professor Adolph Wurtz, For. Mem. B.S. ........ 448 On the Movement of Gas in “ Vacuum Discharges..” By William Spot- tiswoode, P.R.S8., and J. Fletcher Moulton, F.R.S. .............csssscesresscssseessee 453 astiot Presents.c.4. eee eee liiliwi ——— 455 The Effects of certain Modifying Influences on the Latent Period of Muscle Contraction. By Gerald F. Yeo, M.D., F.R.C.S., and Theodore Cash MOD. scesssassdsonesessse ot cceseebeeneats sstecuasteceeosicsorssieseatecartetes) ates 462 1X Pa Formule for sn 8z, en 8v, dn 8, in terms of snwv. By Ernest H. Glaisher, Peevemoninity College, CaAmbridSe: ....c. cccccsviceseserevasese-soetecsssnererence: covcseances 480 On the Influence of Coal-dust in Colliery Explosions. No. III. By W. ere earramee CEN IGE EL Me es tcc exsiscu sc celscocuesccats sesesecs isntonstsodcsesusencessieeoeteaueasenss 490 te ee ech Cas cued seacssaeesddeddeentdtidatgelsnidlesboescersonesuerntisvosiusens 497 Obituary Notices :— Sto Megeeavyie PMMA ESE CLOTS 6, escscecustuoscoaceenadinestadsooussdesacdenscersnerascsadersierecocdeeteinse 1 Sesriem rem OMY CTOMNIA oo. cscivcee hes. sbacasnesesieresceneuoesegnnorastoeeucanerssasedecs XV1 ie PaPd SPOT ec 2 535.05 écacedesiegaceiseanccatehoasecs Mea 2 od ates Re urac Ute cnet a oa Xvi MegaMan ere eevee ess tended csc cge Cesatdvdeswuseustagsbosvendhussivestneatbers bereeecs xalbx Berremr rmbce ne AU NUIE EENTNYI: os )ein.c. cxcsssiscotsssstsenshSioacbeversasesosdesscvaveconstaeds XX Beerrons om Philip de Malpas Grey, Bart. .........:..s0scc.sessscsecesssaveessioseees XX Pe rPPIMMIEM OT CISOT CCOLLE) ciceienssvss.cvasessceonesvdeecsdutssoessdoonovrareabenstecie-verseneas XXIV , Van oy _ a) ir eo « > Paaas | ee * i wrt See A VOR VPC PL LOL + OY Oth) 4 Puadson ones BeAe - 5 = 5 ee i Tey 7 7 el ik = AAV, ¥ iF x 7 ‘ eee aS : ‘ . Oy a Fy i ere “ ‘ « + ’ . i Lai - ® Morte neue stalls i, vote nae ; ok . ‘ * ‘ * + anew ee A & ee o » Ay Sy Pe ute pnts ' oA eeu VAN BL tet LAD ace eae tt i. a chica tee eI = ne a ~ bea gis " ee wz ty Oy te : i ye Wee = * ~ , ve ve ra 4 aS : > * \- ee on ye * | ae: 4 re x ie | bd 4 OBITUARY NOTICES OF FELLOWS DECEASED. JAMES CLERK MAxweELt was born in Edinburgh, on the 13th of June, 1831. His father, who was brother to Sir George Clerk, of Pennicuick, was at first known as John Clerk, but adopted the name of Maxwell on succeeding to an estate called Nether Corsock, which had come into the Clerk family through the marriage of a Miss Maxwell. To this estate he added, by purchase, that of Glenlair, the name of which became afterwards closely associated with that of his son. James Clerk Maxwell’s boyhood did not at first give much promise of distinction. He was a quiet and not very sprightly child, though much given to reading, drawing: pictures chiefly of animals, and constructing geometrical models. At the Hdinburgh Academy to which he was sent, he took no leading position among his school- fellows till about the age of thirteen, when his mental faculties began to develop rapidly, so that he was soon in every department among the foremost of his contemporaries. At this school he made the acquaintance of Professor Tait, the present occupant of the Chair of Natural Philosophy in Edinburgh University; an acquaintance which, cemented as it was by kindred pursuits and interests, ripened into a close and lasting friendship. From the Academy he passed to the University of Edinburgh, where, in 1847, he attended the lectures of Kelland and Forbes. For the next two or three years he had the privilege, to him invaluable, of using the class apparatus in private experiments. What was the nature of some of those experiments we may conjecture from a perusal of his paper on Elastic Solids, written during this time, in which he describes some experiments made with the view of verifying the deductions of his theory in its applications to optics. This paper was read to the Royal Society of Edinburgh on Feb- ruary 18, 1850, and cannot but be regarded as a wonderful pro- duction when we consider the age of its author. This was the third paper which Maxwell had addressed to the same Society: the first, “Qn the Description of Oval Curves and those having a Plurality of Foci,” was read for him by Forbes in 1846; the second, under the title “The Theory of Rolling Curves,” was presented by Kelland in 1849. All these papers, therefore, were written before he came into residence as an undergraduate at Cambridge in October, 1850. While an undergraduate at Cambridge, Maxwell carried on his b il studies in a leisurely manner without producing, or at least without publishing, any original work. He became in due course a scholar of the College. He was also elected member of a literary club, coming thereby in contact with some of the most accomplished of his con- temporaries. In January, 1854, he took the degree of B.A., being Second Wrangler, but equal with the Senior Wrangler in the subsequent examination for the Smith’s Prizes. Shortly after taking his degree, he produced a memoir “On the Transformation of Surfaces by Bending.” By bending a surface is meant ‘‘a continuous change of the form of the surface without extension or contraction of any part of it,” and the problem Maxwell set himself was to discover some method at once simple and general in its application for the measurement of the change in question. Besides its main purpose, which was to develop clearer ideas of the theory of bending, there are incidentally scattered through it good expositions of many points in the geometry of surfaces, as, for instance, the discussions on curvature and the deduction of Gauss’s and other expressions for specific curvature. Up to this point we have directed attention to Maxwell’s papers.in the order in which they were published, there being a special interest attaching to them on account of the very early period of life at which they were written. It will be convenient, however, to consider his published papers under some sort of classification, and this we pro- pose to do further on; in the meantime the leading events of his life subsequent to 1854 may now be briefly recorded. In 1855 he was elected to a fellowship at Trinity, which he retained until his marriage in 1858. He was, however, subsequently elected to an honorary fellowship, a distinction which the College confers only upon the most gifted of her sons. The latter honour was shared on the same occasion by Dr. Lightfoot, the present Bishop of Durham, the late Mr. Spedding, editor of Bacon’s works, and Professor Cayley. In 1856 he was appointed Professor of Natural Philosophy in Marischal College, Aberdeen, where he continued till that College was united to herrival, King’s College, and formed into whatisnow known ~ as the University of Aberdeen. In 1858, he married Katherine Dewar, daughter of the Principal | of Marischal College. During his tenure of the Aberdeen Professorship the subjects which | appear to have engaged most of his attention were the Theory of © Colours and the Stability of Saturn’s Rings, his essay on the latter © subject obtaining for him the Adams Prize. He also continued his — study of Electricity, and in 1859 we have the first evidence that he ~ was working at the Kinetic Theory of Gases. In 1860, after the union of the Colleges in Aberdeen, Maxwell — il obtained the Professorship of Natural Philosophy and Astronomy in King’s College, London. While holding this office he produced some of his most valuable electrical papers, as well as two others on Elasticity. During the same period he took a very prominent part in the experiments organised by a Committee of the British Association for the determi- nation of electrical resistance in absolute measure, and for placing the units of electrical measurements on a satisfactory basis. The experi- ments were conducted in the Laboratory of King’s College upon a plan due to Sir W. Thomson. On this occasion Maxwell worked in conjunction with Professors Balfour Stewart and Fleeming Jenkin, and the results were contained in a report to the British Association in 1863. Maxwell continued in London until his father’s death in 1865, when he determined to reside on the Scotch estates to which he had suc- ceeded, and resigned his professorship. For some years after this he led a quiet life at Glenlair, devoting himself chiefly, we may conjecture, to the composition of his Treatises on Heat and on Electricity and Magnetism. The most important memoirs from his pen about this period were on the Dynamical Theory of Gases, read to the Royal Society in 1866. In 1871 he was elected to the newly-created chair of Experimental Physics in the University of Cambridge. His first duties were to plan and superintend the building of the Cavendish Laboratory, which, with appropriate apparatus, was a gift to the University from the Chancellor, the Duke of Devonshire. The admirable arrangements of this building were designed and carried out by Maxwell. In October, 1871, he delivered an introductory lecture, in which he made some very valuable observations on scientific education and the advantages afforded by the study of experimental physics, especially to that class of students in Cambridge which has produced so many distinguished mathematicians. Addressing such students in particular, he warned them of the preliminary difficulties they would have to face in attempting to combine experimental practice with theory, but suggested at the same time motives which should encourage them to persevere in their efforts. | Besides the duties directly incumbent on a Professor of Physics, the preparation of treatises on the subjects of his chair now engaged Maxwell's attention. “The Theory of Heat,” the first edition of which appeared in 1871, was at once hailed as a beautiful exposition of a comparatively new and interesting subject. This work is indeed a model of scientific style, almost unique in the freshness and simplicity of its expositions, and possessing altogether a charm for the student of physical science, such as few other works of the kind are capable of imparting. The Treatise on Electricity and b 2 lv Magnetism was published in 1873; an original and splendid work, destined, it is not rash to predict, to give colour and direction to our speculations on these subjects for many years to come. Nor must we omit another species of work always performed by Maxwell kindly and conscientiously, professorial work, surely, of the very highest kind, that, viz., of reading and reporting on papers contributed to learned societies by young aspirants to scientific fame. This kind of work, of which much fell to Maxwell’s share, is but little known to the outside world, but involves when carefully performed a vast expenditure of time and trouble even on the part of the most accomplished specialist. Besides performing these various duties, Maxwell took an active part in conducting the general business of the University, serving on the University Council, and otherwise, but especially in effecting those changes in the mathematical studies of Cambridge, which may be said to have amounted at this time almost to a revolution. In accomplishing this, his published treatises already referred to bore in themselves a most important part, but the active share he took in drafting the scheme of the new examination, and the admirable ques- tions he constructed in his capacity of examiner, no less contributed to the desired changes which were thus, thanks in a great measure to his sagacity, gradually and skilfully effected. The direct influence of Maxwell on Cambridge studies began to be felt in 1866, when he filled the office of Moderator in the Mathematical Tripos. Maxwell’s questions infused fresh life into the Cambridge Tripos, and, therefore, into the University studies, by the number of original ideas and new lines of thought opened up by them, thus pre- paring for the change of system in 1873, when so many interesting subjects were added +o the examination. From 1871 to 1879, Maxwell’s pen was incessantly busy. He wrote numerous more or less important mathematical papers, as well as a great many essays and reviews, to be found in the pages of ‘‘Nature.” He also contributed several interesting articles to the “‘ Encyclopedia Britannica.” Of his papers published during this period, those which probably rank highest in point of importance are the two memoirs connected with the Kinetic Theory of Gases. Another undertaking in which he was long engaged, and which, though it proved to be exceedingly interesting, entailed a great deal of labour, was the editing of the ‘“‘ Hlectrical Researches’ of the Hon. Henry Cavendish. This work, published in 1879, has had the effect of increasing the reputation of Cavendish, disclosing as it does the unsuspected advances which that acute physicist had made in the theory of Electricity, especially in the measurement of electrical resistance. The work is enriched by a variety of valuable notes, in which the editor has sought to examine Vv COavendish’s views and results by the light of modern theory and methods. Especially valuable are the methods applied to the deter- mination of the electrical capacities of conductors and condensers, a subject in which Cavendish himself showed considerable skill, both of a mathematical and experimental kind. During the later months of 1878, and the beginning of 1879, Maxwell’s health was not good, but no apprehensions of anything serious were felt by his friends. In the month of May of the latter year he looked very ill. Hopes were entertained, however, that when he returned to the bracing air of his country home he would soon recover. But it was not to be. He lingered through the summer months at Glenlair, with no signs of improvement, his spirits gradually sinking. As a last resource he was brought back to Cam- bridge in October that he might be under the charge of his favourite physician, Dr. Paget. Nothing, however, could be done for his malady, and, after a painful illness, he died on the 5th of November, 1879, in his 49th year. It is difficult to convey a correct impression of the variety and extent of Maxwell’s information on all sorts of subjects. Knowledge of every kind was interesting to him, and there were few topics of conversation to which he could not bring his own peculiar light. He was almost as much at home with the students of philosophy and theology as with those of physics. But if there was one subject more than another in which his conversation was always interesting, it was the literature of his own country, his acquaintance with which, and especially with English poetry, was remarkable alike for its extent, its exactness, and the wide range of his sympathies. His critical taste, founded as it was on his native sagacity, and a keen appreciation of literary beauty, was so true and discriminating that his judgment was in such matters quite as valuable as on mathematical writings. He wrote often in verse, chiefly poetical epistles to intimate friends, and occasional epiyrams, but none of these have been published. The published pieces are few in number, all dealing with some scientific move- ment, speculation or incident of the hour, and all conceived in a spirit of happy good-humoured banter. With the exception of ‘‘ Notes on the President’s Address,” British Association 1874, when Dr. Tyndail was President, which appeared in “ Blackwood,” these pieces are to be found in the pages of “ Nature,” under the signature se, The in- vention of this signature is due to Professor Tait, in whose work on Thermodynamics, one of the equations of the subject is written in the d forms, =J CM, the right hand side of the equation being Maxwell’s initials. The list of Maxwell’s published memoirs and writings of every kind, nal exclusive of treatises, isa long one, numbering over 100 papers, many of which contain speculations of a profound character, worked out with elaborate details of calculation. They treat of a variety of subjects, the most important of which are—(1.) Electricity and Mag- netism; (2.) The Kinetic Theory of Gases; (3.) Colour Perception ; (4.) Dynamics, including Astronomical Physics; (5.) Elasticity; - (6.) Optics. The two first named attracted more of his attention than the others, and his writings on them form a sort of continuous series in which we can follow the history of his ideas so as almost to trace their gradual development. Thus, his first memoir on Hlectricity, entitled ‘‘On Faraday’s Lines of Force,” possesses an interest apart from its intrinsic value, contain- ing as it does the germs of the theories and methods which reached their full growth in his great treatise on Hlectricity and Magnetism. This memoir is in two parts, differing in object and treatment. Whilst the first half aims at a vivid representation of Faraday’s conception of lines of electric and magnetic force, the second is a mathematical exposition of what Faraday calls the electrotonic state of bodies, and an analytical investigation, based on Faraday’s laws, of the electro- motive forces acting on a conductor due to the motion of magnets or currents of electricity outside of it. Faraday’s doctrine that electric and magnetic effects are conveyed by a medium and not by action at a distance, found in Maxwell an ardent believer, who set himself the task of searching out by what kind of mechanism this is accomplished. His first attempt at an explanation is contained in a series of papers in the ‘ Philosophical Magazine,” 1861-62. Beginning with magnetic phenomena, he points out that a medium transmitting magnetic action must be under a stress in which there is excess of pressure in all directions perpen- dicular to the lines of force, in other words, a stress consisting of a tension in the direction of the line of force combined with a hydro- — static pressure. in terms of JS. This theorem, which is easily established inductively by indeterminate co- efficients, is as follows: let— F=f) +) +H +P@+ 2. then f(@)=F @) —3F (@) —ZF(@*) —3F@) + gF@) —7FO) + oF @) — the law of the last series being that every term whose index contains a square factor disappears, the others being positive or negative ac- cordingly as the index contains an even or odd number of prime factors. Thus F(#*), F(«#®), F(a’), F(x) all take the coefficient zero, While F(a°) and F(a!°) are positive; but all the prime terms, and such terms as F(a°°), F(a), c&c., are negative. This at once gives— Ln=18n— 41S q,— WS 3n— WS gn + F1S gn — HS rn + ZolSj on — «) On Waite o> en 1881.] Aectprocals of the Prime Numbers and of their Powers. 7 This is the formula given by Mr. Glaisher, and used both by him and by myself in the calculation of =,. In the particular case of n=1, we have— {,=log dog#)—0°31571 84520 73890 [w=ac |.* I have not been able to identify this constant 0°3157.... with any function of a known constant. It does not seem to have any imme- diate connexion with the Hulerian constant y; for log.y= —0°5496, y2=0°33316. There appears no reason why it should be commensurable with any simple function of y. The following results may be useful for the purpose of this or analogous comparisons :— ev=1 ‘781072, e~¥=0 5614595, e~3:=1 -371241,+ eX: 2=0 *7292647,+ el+3,)=1 -982347,+ e143) = 0 -$044525.4 It is worth while to remark that the S series 1+$+4+i+..... begins with unity, whereas the prime series ;+3+1+ .... begins with 4, and omits the unit. The last two tables are given to 15 decimal places, having been calculated to 16 places. Still, the last figure is not reliable. The tables are not continued to very high values of n, because, for such values— S2z—1l=log (Sx) ==, = 2(S7_,— 1) =2lee (S14) =2224; true to 15 decimal places, or more. * There may be some doubt as to the correctness of this expression. This turns on whether the assumption which it involves is justifiable, namely— log {$(a)—} —log (log x) =0 when z= oc, and consequently when both terms on the first side of the equation re- present divergent series. This, however, is not a question which much affects the arithmetic. + Omitting the term log (log ). 8 Mr. C. W. Merrifield. Sums of the Series of the [Nov. 17, Table of the Sums of the Powers of the Reciprocals of the Natural Numbers, S(co )~”, to 16 Decimal Figures, from Legendre. (00000 §=01192 19926 (00000 00596 08189 ‘(00000 00298 035038 (00000 =00149 01554 ‘00000 = 00074 50711 00000 = =00037 =. 25334 (00000 =00018 62659 (00000 00009 31327 "00000 00004 65662 ‘00000 00002 32831 00000 =O0001L 16415 700000 =00000 =58207 00000 =00000 29103 nN. Scapa. 1 log (x ) + i a 0257721 w4256649 +) 201532: 59 2s Ieee 1 64498 40668 48226 4 Sy ery a epee 1 20205 69031 59594 3 Ae ee ees eens 15032327 Wa2s37 3S I OE ara 1 036927 w77ool V43370 a0 GAN hoc eee 1:01734 30619 84449 1 TE ae 1700834 92773" -Si922ay Galieeg iva, Ue 1:00407 73561 97944 38 SUA See One 1-00200 83928 26082 2 Oe eee 1 00099" 45751 "278s ae 1 Yi adem 85 1°00049 41886 04119 4 VO a pce eee 1:00024 60865 53308 0 AS" Octopus 1-00012° 27133 475789 35 TAN eae t-00006 — 12431 s505cueee lbs 2 1:00003 05882 36307 O 1 Oy eae 1 -O0000L 52822" “5940385 9eG | Ware se Ay 100000" “70371. 972637.80 ES > yas eee t-00000 = S872 "93265 20 dS Be al 1:00000 19082 12716 6 74 § Pe. 1 ee yis 1 -00000. 09539 62033 9 1) 1:00000 04769 32986 8 OOS WOM = 8 1:00000 023884 505025 a 1 0 i 1 1 5 i 8 ip 8 sf 0 1 vi 1 4, 1 9 1 2 1 5 1 7 ih 8 1881.] Reciprocals of the Prime Numbers and of their Powers. 9 Table of the Napierian Logarithms of the Sums of the Powers of the Reciprocals of the Natural Numbers, log.S(« )~”, to 15 Decimal Figures. Nn. hoger S (Co). 1 Bake aan log (log « ) 7 yl aa 0°49770 03024 70745 SUE ce, 5c) ok 0184038 41753 91491 2) ere ae 0°07910 98730 67336 5 RE na 0°03626 22596 49228 One tnt tes: 0°01719 43876 02658 7 ene ae 0°00831 46149 69275 SL eRe tee 0-00406 90663 07413 2 3 ee 0:00200 63787 01528 OD 4 ee 0°00099 40808 65669 lL yg aaa 0°00049 40665 33147 ee tess as os 0:00024 60562 78979 113))) | on eat 0:00012 27058 18911 We Ets 25 000006 12462 59468 1) Se ene 0:000038 05877 68496 OMB rts 5.2 o . 1881.] Radiant Heat, and its Conversion thereby into Sound. 37 action of the molecules on radiant heat is as clearly shown in these experiments as in those previously conducted with the experimental tube and thermopile. Upwards of eighty vapours have been tested in regard to their sound-producing power. With regard to aqueous vapour, whose action upon radiant heat even the latest publications on this subject describe as nil, it was especially interesting to be able to question the vapour itself as to its absorbent power, and to receive from it an answer which did not admit of doubt. A number of bulbs about an inch in diameter were placed under the receiver of an air-pump, with a vessel containing sulphuric acid beside them. When thoroughly dry they were exposed to an intermittent beam. The well-dried air within the bulbs proved silent, while the shghtest admixture of humid air sufficed to endow it with sounding power. Placing a little water in a thin glass bulb, and heating it nearly to its boiling point, the sounds produced by the developed vapour are exceedingly loud. The bulbs employed in these experiments are usually about a cubic inch involume. They may, how- ever, be reduced to one-fiftieth or even one one-hundredth of a cubic inch. When a minute drop of water is vaporised within such little bulbs, on their exposure to the intermittent beam loud musical sounds are produced. It is to be borne in mind, that the heat employed in these experi- ments, coming as it did from a highly luminous source, was absorbed in a far smaller degree than would be the heat from bodies under the temperature of incandescence. To render the correlation of sound-producing power and adiather- mancy complete, all the gases and vapours which had heen exposed to the intermittent beam were examined as to the augmentation of their elastic force through the absorption of radiant heat. A _ glass cylinder, 4 inches long and 3 inches in diameter, had its ends closed with transparent plates of rock-salt. Connected with this cylinder was a narrow \J-tube, containing a coloured liquid which stood at the same level in the two arms of the J. The cylinder could be exhausted at pleasure or filled with a gas or vapour. When filled, the sudden removal of a double silvered screen permitted the beam from the lme-light to pass through it, the augmentation of elastic force being immediately declared by the depression of the liquid in one of the arms of the (J-tube and its elevation in the other. The difference of level in the two arms gave, in terms of water- pressure, a measure of the heat absorbed. With the stronger vapours it would be easy with this instrument to produce an augmentation of elastic force corresponding to a water-pressure of a thousand milli- metres. As might be expected, the intensity of the sounds corre- sponded with the energy of the absorption, varying from ‘“ exceed- ingly strong,’ “very strong,” “strong,” “moderate,” “weak,” to 38 Action of Free Molecules on Radiant Heat. —[Nov. 24, ‘inaudible.’ In this connexion reference was made to the interest- ing experiments of Professor Réntgen, an independent and successful worker in this field. In conclusion, the lecture draws attention to the bearing of its results upon the phenomena of meteorology. The views of Magnus regarding the part played by mist or haze, are referred to and atten- tion is directed to various observations by Wells which are in opposi- tion to these views. The observations of Wilson, Six, Leslie, Denham, Hooker, Livingstone, Mitchell, Strachey, and others are referred to and connected with the action of aqueous vapour upon solar and terrestrial radiation. Many years ago the lecturer sought to imitate the action of aqueous vapour on the solar rays by sending a beam from the electric hght through a layer of water, and afterwards examining its spectrum. The curve representing the distribution of heat resembled that obtained from the spectrum of the sun, the invisible calorific radiation being reduced by the water from nearly eight times to about twice the visible. Could we get above the screen of atmospheric vapour, a large amount of the ultra-red rays would assuredly be restored to the solar spectrum. This conclusion has been recently established on the grandest scale by Professor Langley, who on the 10th of Sepcember wrote to the lecturer from an elevation of 12,000 feet on Mount Whitney, ‘‘ where the air is perhaps drier than at any other equal altitude ever used for scientific investigation.” An extract from Prefessor Langley’s letter will fitly close this summary: —‘ You may,” he says, ‘‘be interested in knowing that the result indicates a great difference in the distribution of the solar energy here from that to which we are accustomed in regions of ordinary humidity, and that while the evidence of the effect of water vapour on the more refrangible rays is feeble, there is, on the other hand, a systematic effect, due to its absence, which shows, by contrast, its power on the red and ultra-red in a striking hght. These experi- ments also indicate an enormous extension of the ultra-red rays beyond the point to which they have been followed below, and being made on a scale different from that of the laboratory—on one indeed as grand as nature can furnish—and by means wholly independent of those usually applied to the research, must, I think, when published, put an end to any doubt as to the accuracy of the statements so long since made by you, as to the absorbent power of water-vapour over the greater part of the spectrum, and as to its predominant importance in modifying to us the solar energy.” wat 1881.] Anniversary Meeting. 39 November 30, 1881. ANNIVERSARY MEETING. THE PRESIDENT in the Chair. The Report of the Auditors of the Treasurer’s Accounts on the part of the Society was presented, by which it appears that the total receipts during the past year, including a balance of £1,195 6s. 1d. carried from the preceding year, amount to £8,920 3s. 8d.; and that the total expenditure in the same period, including purchase of stock, amounts to £5,760 19s. ld., leaving a balance at the Bankers’ of £2,241 11s. 8d., and £17 12s. 11d. in the hands of the Treasurer. The thanks of the Society were voted to the Treasurer and Auditors. The Secretary read the following Lists :— Fellows deceased since the last Anniversary. On the Home List. Addison, William, M.D. Hatherley, William Page Wood, Beaconsfield, Benjamin Disraeli, Lord. Earl of, K.G. Johnson, The Very Rev. George Bigsby, John Jeremiah, M.D. Henry Sacheverell, M.A. Billing, Archibald, M.D. Jones, Thomas Rymer. Caithness, James Sinclair, Karl of. | Lloyd, Rev. Humphrey, D.D. Colvile, Right Hon. Sir James | Luke, James, F.R.C.S. William, Knt. Mallet, Robert, C.K. Currey, Frederick, M.A. Rolleston, George, M.D. Davis, Joseph Barnard, M.D. Stanford, John Frederick, M.A. Kgerton, Sir Philip de Malpas | Stanley, The Very Rev. Arthur Grey, Bart. Penrhyn, D.D. Gould, John, V.P.Z.S. Stenhouse, John, LL.D. Greswell, Rev. Richard, M.A. Thornton, Henry Sykes, M.A. Gunn, Ronald Campbell, F.L.S. On the Foreign List. Chasles, Michel. Change of Name and Title. Lindsay, Lord, ¢o Karl of Crawford and Balcarres. 40 Anniversary Meeting. [Nov. 30, Fellows elected since the last Anniversary. Ayrton, Prof. Wiliam Edward. Bates, Henry Walter. Bristowe, John Syer, REE CP. Christie, William Henry Mahoney, M.A. Dickie, Prof. George, A.M., M.D., F.L.S. GJadstone, Right Hon. William Ewart, D.C.L. Grant-Duff, Right Hon. Mount- stuart EK]phinstone. M.D., Macalister, Prof. Alexander, M.D., Sec. R.LA. McLeod, Prof. Herbert, F.1.C., 1ORSY Phillips, John Arthur. Preece, William Henry, C.E. Samuelson, Bernhard, M.I.C.H. Stoney, Bindon Blood, M.A., M.1.C.E. Traquair, Ramsay H., M.D. Watson, Rev. Henry William, M.A. Kempe, Alfred Bray, B.A. Wright, Charles R. Alder, D.Sc. On the Foreign List. Daubrée, Gabriel Auguste. Marignac, Jean Charles Galissard de. Nageli, Carl. Weierstrass, Carl. The President then addressed the Society as follows :— On the occasions of our anniversary our first glance is usually retro- spective, in memory of those once among our numbers, but now surviving only in their works. On our home list we have this year lost more than a score of Fellows. On the foreign list we have lost but one ; that loss will however be severely, if not so widely, felt. In Michael Chasles mathematicians recognise a geometer of unusual powers, who, having devoted a long life to his favourite study, has left an extensive and characteristic train of researches behind him. Buta larger circle of friends recognised in him a great and good man, beloved by all who knew him, and respected beyond the range of his personal acquaintance. Asa pure geometer he belonged to a class of mathematicians for which the Academy of Sciences of Paris has long been justly celebrated; but whose numbers appear liable to a percep- tible fluctuation, perhaps partly owing to the brilliant opportunities and the varied fascinations which modern algebra offers to the student. Eminent in a nation which has always been intolerant of obscurity in Science, he showed in a remarkable degree how much might be elicited through precision of thought and by clearness of exposition from a few well-selected and fertile ideas. Such, for instance, proved to be the consideration of Anharmonic Ratios, the principle of Corre- spondence, and the method of Characteristics. Whether in the latter he had struck a vein so completely out of the range of the analyst, as he himself supposed, may perhaps be still claimed as an open question ; 1881.] President's Address. Al but certain it is that he showed the fertility of the method by con- tinuing to deduce from it an apparently inexhaustible flow of theorems, even after the more serious part of his mathematical work had been done. And there is little doubt that long after the time when many subsequent works have fulfilled their purpose, and have fallen into a natural oblivion, his ‘‘ Apergu Historique,” his ‘‘ Géometrie Supé- rieure,”’ and the fragment of his “‘ Traité des Sections Coniques,” will be regarded as classics in the library of the mathematician. Turning to the home list, the remark made in my last address, viz., that our losses had been mainly among our older Fellows, might be repeated with even more emphasis on the present occasion. Of the twenty-two who have died during the intervening period nine had reached the age of three score and ten, eight that of four score, and one, Dr. Billing, had attained his ninety-first year. In Lord Beaconsfield and Sir James Colvile we have lost two distin- guished members, elected under the statute which gave a new definition of the privileged class a few years ago. Lord Hatherley will be recol- lected as having served on our Council within recent years, and as having often given us very useful advice on subjects requiring the sound judgement of an experienced mind. Although Lord Hatherley would doubtless have been elected, as a member of the Privy Council, under the statute above mentioned, it 1s perhaps worth remark that he was elected under statute previously existing, and that his fellow- ship dated from the year 1833. The late Dean of Westminster furnishes another instance of the wise exercise of a power which the Royal Society has always reserved to itself, notwithstanding the changes made in 1847, of electing from time to time men of eminent distinction in other avocations of life than those of strict science. Of Dr. Stanley’s attainments and merits in those other directions it is not my province to speak ; and, indeed, it is the less necessary that I should do so, for they were so many and so varied that in one way or other they were known to all. But he was conspicuous, both among the members of his own profession and among many others who have neither predilection nor training for actual science, for his genuine and honest sympathy with its principles and its objects, and with the labours of those who cultivate it. In Dr. Lloyd, whose age was coeval with the century, and who was a fellow-worker with Herschel, Whewell, Peacock, and Sir W. R. Hamilton, we seem to have lost one of the links which connected us with a past generation. While himself no mean mathematician, he was distinguished especially in the sciences of optics and of magnetism. In the subject of optics he had the rare opportunity of supplying the experimental verification of Sir W. R. Hamilton’s brilliant geometrical conclusions on the configuration of the wave-surface ; and it was largely due to his patience, his delicacy of touch, and 42 Anniversary Meeting. [ Nov. 30, his almost instinctive sagacity, that the phenomena of conical refrac- tion were first made visible to human eye. In magnetism he assisted in the formation of the great survey of the globe, initiated by Sir H. Sabine, and as director of a magnetic observatory in Dublin he made valuable contributions to the subject. His scientific remains, brought together in one volume, have been a welcome addition to the library both of the mathematician and of the experimentalist. His interest in science and in its promoters was active throughout his long life; and those on whom the honorary degree of LL.D. was conferred at the late meeting of the British Association in Dublin, will always cherish as a pleasant reminiscence the fact of having received it at his hands. Dr. Bigsby was one of the earlier cultivators of Geology. Some of his first studies were made at atime when the subject was hardly a science; but in attaining the advanced age of eighty-nine he lived to see it what it has since become. He founded a medal at the Geological Society, of which he was for many years a member. We are again reminded of the progress which has been made in science, and in the cultivation of it during the present generation by the fact that until the last day of last year we could reckon among our Fellows Dr. John Stenhouse, one of the surviving founders of the Chemical Society. On the subject of our property there is little change to report. Further investments have been made in due course on account of the Fees Reduction Fund. The sale of the Acton estate has not yet been completed, but a deposit is in hand, and a half-year’s interest on the balance has been received. The Charitable Trusts Bill, which was introduced into Parliament last session, and which would have affected our interests had it not been for a clause introduced by our Fellow the Marquis of Salisbury, specially exempting the Royal Society from its operation, was withdrawn. The collection of portraits in the possession of the Society has been enriched by the addition of a portrait of Sir Joseph Dalton Hooker, painted by John Collier, Hsq., at the expense of a considerable number of our Fellows, who were desirous of expressing their sense of the im- portant services rendered by Sir Joseph to the Society, and at the same time of securing a permanent memorial of their late President. It is to be hoped that advantage may be taken of any suitable occa- sions that may arise from time to time of adding to our gallery of histurical records of the great men whom we have reckoned among our Fellows. The Fellows will learn with satisfaction that the first part of the new edition of our library catalogue is published. This part, consist- ing of 232 pages, contains the Transactions, Proceedings, and Journals published by Societies and Institutions in nearly all parts of the world; 1881. ] President's Address. 43 and also the observations, reports, and accounts of surveys which are to be found in our library. As our Library Committee has always devoted great attention to securing by exchange or by purchase publications of this class, and as the main strength of our library consequently lies in our collection of them, the part in question will form the most important section of the entire catalogue. Progress has also been made in the more voluminous portion of the catalogue, viz., that of the general collection of scientific books, of which thirteen sheets, extending to the letter C, are printed off, or are in type. It may fairly be hoped that before our next anniversary the whole will be published. The last part of the Philosophical Transactions for 1880 was pub- lished in March of the present year, completing a volume of nearly 1,100 pages, with upwards of fifty plates. Of the Transactions for 1881, Parts 1 and II have already appeared ; from which an early publication of Part III may be anticipated. Of the Proceedings, vol. 31 was published in June, and vol. 32 at the end of October. Although, as I remarked last year, we are more concerned with the quality than with the quantity of the communications made to the Society, it may still be interesting to carry on the table of the number of papers presented per annum to a tenth year. It stands as follows :— 1872 Ets te 99 papers received. 1873 ye nie SE hamep s 1874 Be Se TO vn dens 3 1875 a “te Si. rf 1876 sis st eeu UI sae bs 1877 be a OE taeeGs . 1878 Ae Sa Wee On uae. F 1879 a SEMIS 2 ae . 1880 oe ead eel AS iat) 8 * 1881 A Rinne 27a he . These 127 papers include one from Mr. Brooks of Baltimore, two from Professor Helmholtz, and one from Captain Mannheim, of the Ecole Polytechnique, Paris. On reference to the papers them- selves it will be noticed that several prominent men are carrying on with vigour the series of researches on which they have been, in some cases for years, engaged. Among them there may be mentioned, in physics, those of Professors Liveing and Dewar, and of Mr. Lockyer, on the Spectra of Terrestrial Substances and of the Sun; those of Pro- fessor Hughes on minute Interactions of Electric Currents and Mag- netism; those of Mr. Crookes on High Yacua; and those of Mr. H. Tomlinson on the effect of Stress and Strain on the action of Physical 4A | Anniversary Meeting. [Nov. 30, Forces. Mr. G. H. Darwin continues his already classical memoirs on the mechanical history of the solar system; and Captain Abney has opened out to view, by photographic means of his own invention, a part of the spectrum of the sun and of other bodies, beyond the red, hitherto invisible; and last, but not least, Professor Tyndall in his Bakerian Lecture has given an account of his researches on the action of free Molecules on Radiant Heat, and its Conversion thereby into Sound. In Biology, I may mention the investigations of Mr. Romanes on nerve systems; those of Professor Ferrier on tbe connexion between special portions of the brain and special motor organs of the animal system; those of Mr. Parker on the Skull of the Batrachia, and of Professor W. C. Williamson on the fossil plants of the Coal-measures. Among the newer subjects, the experiments of Dr. Young and Professor George Forbes on the velocity of light of different colours have naturally arrested considerable attention, for several reasons and especially because the conclusions thence deduced, if ultimately established, would fundamentally modify our views of the constitution of the luminiferous ether. For several years past I have been able with much satisfaction to report that there had been no change in the staff of officers of the Society. I much wish that I could have done so again. But the longer a capable man lives and is available, the more will work accu- mulate on his hands; and the time at last comes when something must be given up, lest, in the multiplication of avocations, powers which might otherwise have been devoted to some great and good purpose, and on operations not within the grasp of everyone, should become dissipated among a variety of objects. A feeling that life must not be spent merely in running hither and thither, and a desire that 1t should be something better than a mere feat of mental agility exhibited in passing rapidly from one occupation to another, doubtless operated in leading Sir Joseph Hooker to resign the Presi- dentship; and a similar feeling has recently led to the resignation of the Secretaryship by Professor Huxley. That this loss is great will be felt by every Fellow of the Society ; 1t will be more keenly felt by his brother Secretaries and the Treasurer, but most of all by your President. Connected as I have been with him through a series of years by ties of office in the Society, by bonds of friendship and trust as thorough as can exist between man and man, I cannot but miss for a long time to come his ever willing support, his sound counsel and advice, and the cheery manfulness with which he would always address himself to any business however difficult, uninviting, or heavy. The post is one which it is not easy to fill. Many qualifications go to make up a good Secretary ; and although none of us so “ despaired of the republic”? as to doubt that a good successor would be found, we still felt some anxiety until we were in a position confidently to 1881.] President's Address. A5 recommend a name for your consideration. Professor Michael Foster’s great scientific attainments, his administrative powers as shown in founding the great School of Biology at Cambridge, the confidence with which he inspires all around him, alike point him out as a man eminently fitted for the post. It would indeed have been agreeable to your President to have had one of the principal Secretaries resident in London; but the means of communication are now so different from what they formerly were, that questions of distance almost disappear ; and itis certainly not without its advantages that the two principal Secretaries, if not resident in London, should reside in the same city. In the course of the spring of the present year, Sir Joseph Copley, the present representative of the Founder of the Copley Memorial, explained in a visit to the President his wish to ‘‘ provide in per- petuity a yearly bonus of £50, to be given to the recipient of the Copley Medal.” As the donor’s views on the terms of the gift were completely made up, and were not offered for discussion by the Society, or otherwise open to modification, the Council decided to accept the offer in the spirit in which it was made, and on the terms prescribed. In accordance with this, Sir Joseph transferred a sum in Consols sufficient to provide for the bonus proposed. This acceptance will not in any way affect the adjudication of the Medal, nor, it is to be hoped, the high estimation in which that award has always been held. The period of five years during which the experiment of the Government Fund of £4,000 per annum was to be tried, has now expired. In a former address I have expressed opinions gathered from many of the Fellows of the Society, and have indicated my own. The President and Council have now, at the request of the Department of Science and Art, through which the vote is made, drawn up a report on the question, based upon the experience gained up to the present time, and have made suggestions with a view to a modified arrangement for the future. The Society will be duly informed of the result of those communications. In the mean time it may not be out of place to remind the Fellows that a statement of all grants made within the year is published in the report of our anniversary proceedings. The Report of the Challenger Expedition, of which mention was made last year, is in the course of publication; and three volumes have now appeared. Copies of these have been presented by the Treasury to our hbrary. Volumes II and III refer to the curious forms of life found in what Sir Wyville Thomson has called the “Abysmal Region,” and are copiously illustrated with lithographs. The interest which attaches to this publication is evinced by the fact that the first edition of the second volume is already exhausted. A second edition of it is in the course of printing. The Fellows will A6 Anniversary Meeting. | Nov. 30, doubtless have observed, that the printing of the text and the execu- tion of the plates are maintained at the same high standard as that exhibited at the outset. Among other scientific publications of the year, | may mention the third volume of Roscoe and Schorlemmer’s work on Chemistry, Mr. Balfour’s work on Comparative Embryology, and Mr. Darwin’s on Vegetable Mould. In December last the Council authorised the loan of the “ Philo- sophical Transactions” from one of our complete sets, five volumes at atime, to the Delegates of the Oxford University Press, for the preparation of a Philological Enghsh Dictionary, under the editor- ship of Dr. Murray. It is hoped that this loan will contribute to the completeness of the work im respect of scientific terms. Forty-one volumes have been already utilised in this way. Towards the close of last session a communication was received from the India Office enclosing a copy of a report and memorandum, on Pendulum Observations, by Major Herschel, and asking the advice of the President. and Council thereon. Subsequently there followed another communication from the same office, enclosing a copy of a letter from the same officer, with an extract from a letter to him from Mr. Peirce of the United States Coast Survey. These documents were referred to a Committee consisting of Sir George Airy, Professor J. C. Adams, and Professor Stokes. The Report of that Committee was forwarded to the India Office; the following extracts from it contain those parts which refer to the main scientific questions raised :— ‘“‘'The object in referring these documents to the Royal Society was to assist the India Department in coming to a conclusion as to what, if anything, might yet be required in order to render the pendulum operations which have been carried out in connexion with the great trigonometrical survey of India reasonably complete as an important contribution towards the determination of gravity all over the earth. ‘“‘ At present the stations which have been directly connected with the Indian stations are confined to Aden, Ismailia in Egypt, and Kew; and no one of these has been differentially connected with any of the chains of stations that have hitherto been used in the deter- mination in this way of the figure of the earth, though Kew is now a station at which an absolute determination has been made. We think it would be a reasonable expectation on the part of the scientific public that the Indian group of stations, which have already been connected with Kew, should be differentially connected with at least one chain of stations which are so connected with one another, and which have been employed in the determination of the figure of the earth. “We approve accordingly of the suggestion that gravity at Kew 1881 | President's Address. 47 should be compared, by means of invariable pendulums, with gravity at another station belonging to another group. Greenwich has been named as such a station. ‘*In connexion with this subject, we would refer to the suggestion, which has been brought before us, made by Mr. Peirce, of the United States Coast Survey, that Major Herschel should swing the same two pendulums that were used in India, first at Kew and then at Washington. ** As Washington is, or shortly will be, connected differentially with a large chain of stations widely distributed in America and else- where, we think that the value of the Indian series would be decidedly increased by being connected with one of the American stations, such as Washington. We think, however, that its con- nexion through Kew with one of the older series should not on that account be omitted. “The observations required for the purpose of these connexions are such as certainly can be made, and have been made, by existing methods ; and the labour of making them, which will be approximately in proportion to the number of stations at which the pendulums will have to be swung, is only a fraction of that already incurred on the Indian stations, and the three which have been included in the same group with them.” In October last a letter was received from the Treasury asking the opinion of the President and Council respecting arrangements for observing the Transit of Venus in 1882. Under the advice of a Com- mittee appointed for the purpose, it was recommended that a special Committee of the Royal Society should be appointed to decide upon the observations considered essential, and to advise Her Majesty’s Govern- ment as to the best method of carrying them out. In conformity with this advice, and at the request of the Treasury, a Committee was appointed to draw out a scheme of stations, and of the constitution, strength, and equipment of the observing parties, and to frame an estimate of the total cost. The Committee reported recommending the adoption of certain stations in South Africa, the West Indies, Australia, and New Zealand, and the Falkland Islands; and they at the same time added other particulars, and furnished an estimate of the whole, adopt- ing in the main the recommendations of that Committee ; the Treasury then requested the President and Council to nominate an Executive Committee, by which (accounting to the Treasury) any vote of Parlia- ment for the purpose of these observations might be administered ; and under whose advice the observers and assistants might be selected and appointed. In compliance with this request the following Fellows were nominated as an Executive Committee, viz., the President, Professor J. C. Adams, Sir G. Airy, Mr. Hind, Sir G. Richards, Professor H. J. Smith, and Mr. Stone. That Committee is now con- 48 Anniversary Meeting. [ Nov. 30, tinuing its labours, and has appointed its member, Mr. Stone, of the Radcliffe Observatory, Oxford, directing astronomer of the expedi- tions; and under him the selection of instruments, as well as the training of the observers, will be made. Witha view of making the observations ultimately as comparable as possible, the Committee, at an early stage, put itself, through the Foreign Office, into communication with the corresponding Commissions in foreign countries, on the subjects of the instructions to be given to the various observers; and a draft set of instructions, drawn up for this purpose, was circulated for comment and suggestion. Moved perhaps in some degree by this action, the Government of France took advantage of the assemblage of scientific men collected in Paris for the Electrical Congress and Exhibition, to summon a Con- gress of Astronomers, having especially in view a consensus of arrange- ments for the observation of the Transit. This Congress met in Paris on the 5th of October, under the auspices of the Minister of Public Instruction. M. Dumas was appointed President; MM. Foerster and Weisse, Vice-Presidents; MM. Tisserand and Hirsch, Secretaries. The various countries of Hurope were represented; but it was a matter of much regret that no representative from the United States of America was present. Mr. Stone attended on behalf of the British Committee. J must here express my regret at having been unable to attend in person to support our Directing Astronomer, who made the journey at much inconvenience to himself; but I should at the same time add that my absence in no way diminished the effective- ness of Mr. Stone’s counsels, which proved of great service in pro- moting a unanimity in the views finally adopted by the Congress. Two Committees were appointed (1) for the selection of stations ; (2) for a discussion of methods of observation. As the British stations had been already chosen and did not admit of material alteration, the first of these Committees did not directly concern us. But, judging from the number of observations con- templated to be made in South America by foreign expeditions, it seems not impossible that the party which we had proposed for the Falkland Islands might be advantageously transferred to some other locality, so as to strengthen the parties requiring support, for example, in Australia. As regards the discussion of methods, the draft instructions drawn up by the British Committee, and especially the definition of contact to be observed, strongly insisted upon by Mr. Stone, were in the main adopted. The following are the principal points agreed upon :— With a view to uniformity of method of observation, it is necessary that instruments of nearly the same aperture, 6 inches, should be used, also that the observations of contact should be made in a field of just sufficient brightness to allow of the clear separation Ls 1881. ] Presidents Address. | 49 of two threads at one second of arc apart when seen projected on the sun with a power of 150. The times corresponding to the internal contacts should be defined as follows :— At Ingress.—‘‘ The time of the last appearance of any well-marked and persistent discontinuity in the illumination of the apparent limb of the sun near the point of contact.” At Hyress—“ The time corresponding to the first appearance of any well-marked and persistent discontinuity in the illumination of the apparent limb of the sun near the point of contact.” It is a point of primary importance that all the observers shall, as far as possible, observe the same kind of contact; and it is therefore desirable that the times recorded for contacts should refer to some marked discontinuity in the illumination of the sun’s limb about which there cannot be a doubt, and which may be supposed to be recognisable by all the observers. If a pure geometrical contact is alone seen, there can be no doubt about the time which should be given; but, if haze is noted, it should be haze nearly as dark as the outer edge of the planet ; and if a ligament is seen, it should be nearly as dark as the outer edge of the planet. A further proposal was made to establish a Central Bureau in Paris to receive and discuss the observations, and to enter upon other work more or less directly, connected with the determination of solar parallax. But, as this question was not contemplated in the instruc- tions given to our representative, and indeed exceeded the powers of the British Committee, no definitive resolution was passed on the subject. On the subject of the longitude of a point in Australia, to which I made allusion in my address last year, as important for the observa- tions of the Transit of Venus, I have lately received a letter from Mr. Todd, of the Observatory, Adelaide, from which the following is an extract: “‘ With regard to the determination of Australian longi- tudes: as it is understood that Lieut.-Commander Green, U.S.N., will call at Port Darwin to determine its longitude by signals from Singapore on the one side, and with the Adelaide Observatory on the other, I have taken no further steps for going to Port Darwin as previously arranged. I shall take all the necessary observations here, and exchange signals with Lieut.-Commander Green over my over- land telegraph; and, in conjunction with Messrs. Ellery and Russell, make fresh determinations of the difference of longitude between Adelaide, Melbourne, and Sydney.” Since our last anniversary, Sir George Airy, the late Astronomer Royal, having completed his eightieth year, and nearly half a century of office, has retired. Of his services to science, and to this Society as President, and in other ways, the time to speak has happily not yet arrived. His great intellectual powers are in fact in no way impaired, WOL: XXXII. E 50 Anniversary Meeting. [ Nov. 30, and so far from having brought his period of activity to a close, he hopes to employ his well-earned leisure in completing a favourite work, the Numerical Lunar Theory. His successor, Mr. Christie, from his long experience in the Royal Observatory, will combine a thorough training in the remarkable organisation and methodical administration for which his predecessor was so conspicuous, with the full vigour of life, and an active interest in the more modern developments of astronomy, in which he is already distinguished. The future of the Royal Observatory is a subject on which the mind of Sir George Airy often exercised itself, and to which he alluded more than once in his Reports to the Board of Visitors. With his fundamental proposition that, observational astronomy, in its bearing on the improvement of navigation, must always be its main line of work, every one must agree. Over and above this, the expressed wish of the Board of Visitors, and the practice of the last few years, have already sanctioned the addition to the ancient duties of the Observatory of some of those long and systematic series of observations, such as that of the solar protuberances, and the motion of the fixed stars in the line of sight as shown by the spectroscope, which are beyond the scope of an amateur, and above the power of any individual astronomer, however devoted to his work, to permanently maintain. How far it may be desirable to continue magnetic and meteorological observations beyond the necessities of an astronomical observatory, are questions which will doubtless engage the attention of the present director. The main question must be, what distribution of these branches of study among Greenwich, Kew, and other establishments, will in the end best conduce to the progress of science. And with a view of giving full scope to the judgment and skill of the present and future holders of the office the Board of Admiralty have, as I understand, decided to consider a revision of the terms of the Royal Warrant under which the appoint- ment is made. This year has been signalised by the meeting of a most important scientific congress—the International Congress of Electricians, held at Paris. The recent developments of the practical applications of electricity rendered the occasion favourable both for organising a special exhibition devoted solely to this branch of science, and also for assembling the electricians of all countries. The general purpose of this Congress was to discuss, and, if pos- sible, to settle, some of the numerous difficulties which perplex both the physicist in his studies and the constructor in his work. But chief among the subjects proposed to, and undertaken by, the Congress was that of fixing a system of electrical measures for inter- national adoption. 1881. | Presidents Address. bt Perhaps in no subject is the necessity of uniformsystem of standards so striking as in electricity. This science, both in its practical appli- cations, such as telegraphy, and in the great natural problems of terres- trial magnetism and atmospheric electricity, refuses to recognise any artificial divisions of the surface of the globe, whether ethnological or political. It rarely happens, in operations undertaken on so large a scale as the study of electricity and its industrial applications, that an opportunity presents itself of arranging for concerted and har- monious action through a period extending to a distant future. Before a branch of industry has attained sufficient importance to claim international recognition, it has usually gone through the process of considerable development in different countries; and in each of these developments it has often received a stamp of local character which makes it difficult to reduce the whole to one uniform system. But in the case of electricity there were fortunately present special circum- stances which facilitated the adoption of uniform standards. Foremost among these was the fact that the development of its practical apph- cations, in other departments than telegraphy, were so recent that it was not too late to legislate for it as though it were but just about to begin. Secondly, the international character of telegraphy, and the fact that the manufacture of its apparatus had always been confined to the great centres of civilisation, had both tended to limit the number of existing systems of measurement, and prevented thas multiplicity of standards which would certainly have arisen had such manufacture been carried on in numerous and in isolated localities. But by far the most important influencing circumstance was the happy idea due to the British Association of adopting standards based on absolute measures. The Association did not allow the idea to remain barren; but, through the instrumentality of its Com- mittee on Hlectrical Standards, it gave to the world the admirable units of the Ohm, the Volt, and the now re-christened Weber ; and the eminent men who formed that Committee may now point with honour- able satisfaction to the fact that the Hlectrical Congress decided unanimously to recommend for universal acceptance those units which that Committee so early adopted. With the single exception of the unit of current which, in order to avoid an ambiguity in the signification of Weber, receives the title of Ampére, the names are left substantially without change. The adoption of these units for international use is to be preceded by a new and more careful redetermination of the ohm at the hands of the great physicists of all nations. And it is intended that this redetermination shall result in a standard for general adoption. Thus electricity will be the first of the practical sciences to be freed from all difficulties due to local standards; and it is to be hoped that this example may be followed in other sciences concerned with practical life. E2 52 Anniversary Meeting. [Nov. 30, The following, are the actual resolutions adopted by the Inter- national Congress of Electricians at the sitting of September 22nd, 1881 :— 1. For electrical measurements, the fundamental units, the centi- metre (for length), the gramme (for mass), and the second (for time), are adopted. 2. The Ohm and the Volt (for practica] measures of resistance and of electromotive force or potential) are to keep their existing defini- tions, 10° for the Ohm, and 108 for the Volt. 3. The Ohm is to be represented by a column of mercury of a square millimetre section at the temperature of zero Centigrade. 4, An international commission is to be appointed to determine, for practical purposes, by fresh experiments, the length of a column of mercury of a square millimetre section which is to represent the Ohm. 5. The current produced by a Volt through an Ohm is to be called an Ampere. 6. The quantity of electricity given by an Ampére in a second is to be called a Coulomb. 7. The capacity defined by the condition that a Coulomb charges it to the potential of a Volt is to be called a Farad. The remainder of the work of the Congress consisted mainly of the discussion of various interesting questions bearing upon electricity; and although these did not in many cases issue in precise recommend- ations, yet they were not altogether devoid of practical results: The questions which chiefly attracted its attention were those of terres- trial magnetism and earth-currents, atmospheric electricity, and the more practical but perplexing question of lightnimg conductors. In all these matters the need of close and continuous intercourse between the observers of different nations was strongly felt; and the Congress passed resolutions recommending combined action both in the way of observations carried on simultaneonsly and with like apparatus, and also of frequent if not continuous telegraphic communication of the results of these observations. The organisation of so extensive and perhaps so costly a system of combined observations must depend to a great extent on the various Governments, and also on the goodwill and generosity of the great telegraphic companies; but it is much to be wished for the sake of science, that some progress in that direction may soon be effected. The present state and prospects of electro- physiology also received careful discussion, but the difficulties of the subject precluded any definite conclusions. The same was the case with the question of photometry as applied to the intense hght with which electricity furnishes us. Resolutions recommending the adop- tion of certain provisional photometric standards were passed; but these only evidenced the strong feeling that prevailed in the Congress, that some new departure must be made, and that a new standard 1881.] President s Address. 53 of illumination (such as perhaps the glow of platinum on the point of fusion) must eventually be adopted for electric lights. I have described the more important of the results of the delibera- tions of the Congress. Perhaps, however, the most important of all (with the exception of the choice of electrical units) will prove to have been the impetus given to electrical science by the inter- change of ideas that took place among the leading physicists of all nations, and the light that was thrown on the various problems which came under discussion in the meetings of the Congress. I cannot conclude this imperfect sketch of this important Congress better than by quoting the eloquent words of M. Dumas at the con- clusion of its sittings :—‘‘ Greek mythology, in its happy personifica- tion of the forces of nature, placed the winds and the waves under the direction of divinities of the second rank; it made the celestial representative of light its god of poetry and of the arts; and by an admirable forethought, it reserved lightning for Jupiter. Science and industry have long since laid their hands on the forces which air and water have placed at the disposition of man. Steam, animated by fire, has enabled him to overcome many obstacles and to rule the waves. Light has no longer any secrets from science, and the arts are daily multiplying its marvellous applications. But there remained one labour to accomplish ; namely, to wrest lightning itself from the hands of the ruler of the gods, and to bend it to the needs of humanity. This is the feat which the nineteenth century has now accomplished, and of which this Congress is the evidence and the witness. This feat will mark an epoch ever memorable in history; and, amid the turmoil of politics and of questions which agitate the human mind, it will be recognised as the characteristic feature of our era. The nineteenth century will be the century of electricity.” After the Congress, one of the most remarkable events during the present year has undoubtedly been the Electrical Exhibition in Paris. I do not of course purpose to describe it, as many of our Fellows visited it; and full descriptions have reached us through various channels. One point, however, must have struck those who examined any considerable number of the objects; and this I mention, not as in any way disparaging them, but rather as illustrating the stage to which electrical science has attained ; namely, that while the assemblage of instruments and appliances was in every way remarkable, and while very great ingenuity and skill had been expended on their contrivance and construction, yet the amount of novelty in the principles involved was comparatively small. Of new combinations, 1mproved methods, and adaptations in detail there was abundance. Some of them even removed former inventions from the category of curiosities to that of instruments for practical employ- meni; or enlarged their sphere of utility from that of the laboratory 54 Anniversary Meeting. [Nov. 30, to that of everyday use. But such is the mass of fruitful matter which science has furnished to the mechanician and constructor, that we might almost wish, from the point of view of the latter, that they may have time to work out more fully than has yet been done, the results of science, before they are called upon to elaborate any fresh materials. It is now proposed to repeat as far as may be, this Exhibition, at the Crystal Palace; and the energy with which the proposal has been taken up, and the response with which it has met in many quarters, appear ‘to justify sanguine expectations of its success, at all events from a practical and popular point of view. From the side of science, it would doubtless have been far more interesting to look forward to a fresh Exhibition, either here or elsewhere, of the pro- gress of electricity after an interval of two or three years. But there is nothing in the present undertaking to interfere with the more advanced project, if, after some such period as that indicated, circum- stances should prove favourable. In the meantime, it must be remembered that there are very many persons to whom the Paris Hixhibition would have proved both interesting and instructive, but who, from one cause or another, were prevented visiting it. Be- sides this, there are not a few commercial, and even municipal, bodies desirous of adopting some of the modern applications of electricity, but who would be more ready to avail themselves of them after a personal inspection of the instruments and of their mode of action. rom this point of view the Exhibition may fairly be expected to give considerable impulse to the adoption of electrical appliances in fresh quarters. But even over and above this practical aspect of the undertaking, there may still have been at the epoch of the Paris Exhibition, some results on the eve of achievement, some remedies for defects, sufficient to transform a doubtful into a certain issue, or even a failure into a success; some steps which may open out new questions, or serve as a departure for new investigations in the subject of electricity. It such should be the case, even science may derive substantial benefit from the proposed undertaking. But the present year has been rendered generally remarkable, amongst other things, by the multiplicity of its Congresses. Apart from those which are concerned with subjects not coming under the head of ‘‘ Natural Knowledge,” there have been held the annual meetings of the British Association, and of the Iron and Steel Institute; the International Medical Congress, in London; the special Congresses on Electricity and on the Transit of Venus, in Paris (mentioned above) ; that on Geography in Venice; that on Geology in Bologna, and others. Among all tnese, the International Medical Congress which this 1881. |] President's Address. 5S year met in London, stands conspicuous. The work of that meeting showed that the study of medicine by the real workers is, in every part, even the most practical, pursued in a thoroughly scientific spirit ; that facts are industriously collected, and patiently grouped and com- pared ; and that conclusions are, if sometimes hastily drawn, yet very cautiously accepted. And there was ample evidence that help, whether in apparatus or in knowledge, is eagerly accepted from all the other sciences whether their range be far from, or near to, the biological. In short, in the opinion of those best qualified to form a judgment, it is not too much to say that the whole tone of the proceedings of the Congress, though chiefly concerned with practical questions, was, in the best sense, even in the sense which the Royal Society would give to the term, scientific. Several of the societies meeting annually, or at longer periods, have organisations which, during the intervals between two successive meetings, do useful work. But in all cases the meetings form the most prominent, if not the most important feature of their life; and, speaking particularly of the meetings themselves, the question has more than once been raised whether they continue to justify the efforts necessary to bring them about. It has been argued that, so many are the scientific periodicals in every civilised country, that all the papers of importance communicated to the meetings would under any cir- cumstances be published in some place or other. Again, it has been urged that, so numerous are the centres of science, so many the means of communication both between places and between persons, that the necessity for these gatherings has, in the natural course of events, become superseded. ‘The time which such meetings and the prepara- tion fur them involve, and the trouble which they entail on men already burdened with much work, have also been pleaded on the same side, and objections have been taken on the ground of the useless and irrelevant matter which is too apt to crop up on these occasions. These arguments are certainly not without weight; but there is still another side to the question. It is, indeed, quite probable that all the more important papers would be published even if the meetings never took place at all. But at these meetings there are usually a number of communications, many, but not all, of local origin, the production of which has been stimulated by the meeting itself; and a fair number of these may be reckoned on the side of gain. Again, it is true that the original idea of a parade or march past of scieuce, valuable enough when the provinces heard or saw little of science, has become less important now that provincial centres are to be found in almost every large town in the country. Nevertheless, the mere presence of some of the leading men stimulates dormant powers and encourages rising aspirations; and this perhaps all the more the case for the very reason that science and scientific names are no longer unknown. That 56 Anniversary Meeting. [Nov. 30, most of the leading men have opportunities of meeting from time to time, and for scientific purposes, is certainly true; but that they should meet also on occasions when science is not too formal, is a thing which has its uses. Anda concurrence of minds more numerous and more diversified than usual is sure to be fruitful of results. The whole advantage of these meetings, however, depends ultimately and funda- mentally on the presence of a strong scientific element, which, from its own mere dignity and character, will repress all that is unworthy and will leaven the whole lump. Acting on this principle as a scientific duty, many good men have attended these meetings; and although they may have approached them with some degree of reluctance, few who during their attendance have taken their fair share in the proceedings, have come away without having derived a more favourable impression than that with which they entered. Of such gatherings, the late meeting of the British Association at York was, if I may be permitted to express an opinion, a pattern and exemplar. And although it cannot be expected that in every year there will be so strong a muster as on the occasion of the fiftieth anniversary, yet all well-wishers of the Association must feel that it has entered upon its second half century with vigour and with dignity, and that it now remains only for its future supporters to maintain the high standard with which it has been handed down by those who have gone before. It may be a matter of regret, although doubtless inevitable, that the same causes which have affected the social, the intellectual, the industrial, and the political life of our generation, and have made them other than what they were, should affect also our scientific life; but, as a matter of fact, if science is pursued more generally and more ardently than in former times, its pursuit is attended with more haste, more bustle, and more display than was wont to be the case. Apart from other reasons, the difficulty, already great and always rapidly increasing, of ascertaining what is new in natural science ; the liability at any moment of being anticipated by others, constantly present to the minds of those to whom priority is of serious importance; the desire to achieve something striking, either in principle or in mere illustration ; all tend to disturb the even flow of scientific research. And it is perhaps not too much to say that an eagerness to outstrip others rather than to advance knowledge, and a struggle for relative rather than for absolute progress, are among the dangerous tendencies peculiar to the period in which we live. I do not, of course, for one moment mean to imply that this tendency universally prevails ; for in Science, as well as in other pursuits, I believe that the best of the present would well stand comparison with the best of the past, and that there are nowadays men in the mid-stream of life who are as little affected by the eddies and back-waters with which they are sur- 1881.] President's Address. Da rounded as were the giants of former days. Nevertheless the danger is a real one and is to be met with at every turn. But the part of Cassandra is neither agreeable to the player nor welcome to the audience ; nor is it indeed necessary that I should play it; for, even although what J have said be true, it is still, I trust, not the whole truth. I have already spoken of noble exceptions; but, although noble exceptions may go far to redeem the character of a nation or of a period, and example may have influences of which we hardly dream, yet for a general remedy I am more inclined to look to the natural course of events, and to what is often loosely spoken of as “things curing themselves.” Such a cure may perhaps come about somehow on this wise. So multitudinous are the workers in every science, so numerous are the channels through which their discoveries are chronicled, that it is becoming every year more difficult for even the learned and the well read to say what is and what is not new, or what has not been published before. Claims for novelty must, therefore, as time goes on, be put forward with greater and greater difidence. The only originality that can be safely claimed will be originality on the part of the investigator; and the question of absolute priority must be left to the verdict of time and of that sifting process by which ultimately all discoveries will find their proper places in the Temple of Science. When this stage is reached, and we are even now approaching it, the fever of to-day may in a great measure subside and give place to a more tempered, although still fervent, glow of aspiration. The eagerness and haste to which we have become almost accustomed may be chastened by the reflection that questions of priority are not to be settled by a mere stroke of the pen, and that in the comparison of rival claims the question of the quality of work will undoubtedly arise and become interwoven with that of priority. And so, in the end, it ‘may come to pass that a half-understood experiment or a hastily drawn conclusion may avail less than ever for establishing a reputa- tion, and that, even for the purpose of winning the race, 1t may be worth while to spend sufficient time in laying sure foundations and in building a superstructure commensurate with that on which it stands and. well: proportioned in all its parts. The transference of the Natural History Collections of the British Museum to the new building at South Kensington is still in progress. It is hoped that the building for the specimens preserved in spirits, as well as the fittings for the zoological department, will be so far com- pleted as to allow of the moving of that department during the autumn of 1832. The lighting of the reading room by Siemens’ lamps is so far satisfactory, that it has been decided to keep that room open in future until 8 P.M., instead of 7 p.m. This change, it is hoped, will prove to be of substantial service to a large class of readers. 58 Anniversary Meeting. [Nov. 30, The Institution founded in 1851, under the title of the Government School of Mines and Metropolitan School of Science applied to Mining and the Arts, for the instruction of students in those branches of Science which are mdispensable to the Miner, the Metallurgist, the Geologist, and the Industrial Chemist, has this year been organised afresh, and, under its new title of the Normal School of Science and Royal School of Mines, adds to its former functions the training of teachers for the Elementary Science Classes under the Science and Art Department, the multiplication of which, in recent years, is a significant indication of the rapid spread of scientific imstruction throughout the country. The accommodation requisite for practical teaching being inadequate in all cases and totally wanting in respect of many of the classes, in the Museum of Practical Geology in Jermyn Street, and in the Royal College of Chemistry in Oxtord Street, all the instruction, except that in Mining, has been transferred to the Science Schcols at South Kensington. The staff of Professors and Lecturers has been in- creased, and provision has been made for the teaching of various important subjects, such as Mathematics, Drawing, Botany, and the Principles of Agriculture, which were either omitted, or insufficiently represented, in the original programme of the school. Under its new organisation, the Normal School of Science and Royal School of Mines will not merely supply from among its associates persons highly qualified to apply the principles of science to the Mining, Metallurgical, Chemical, and Agricultural industries of the country, and properly trained science teachers ; but, through the exhibitions attached to the yearly examinations of the Science and Art Department, it will place within reach of promising young students in all parts of the country, whose means do not enable them to obtain the benefits of a University education, such a training as will enable them to tisn their natural abilities to account for the advance- ment of science and the improvement of its applications to industry. Under the latter point of view, the instruction given in the Normal School of Science will lead up to the special technical training of the Central Institute of the Guilds of the City of London. Under the auspices of the City and Guilds of London Institute, further progress has been made during the past year in the promotion of Technical Education. It will be remembered that the work at pre- sent undertaken by the Institute embraces the establishment of a Technical Science School in Finsbury, a Technical Art School in Kennington, a Central Institution or Higher Technical College in Kensington, the subsidising of existing institutions, affording facilities for Technical Instruction and the encouragement of existing classes in the manufacturing centres by the grants paid to teachers on the results of the Technological Examinations. 1881.1 President's Address. 59 In May last the foundation stone of the Finsbury College was laid by H.R.H. Prince Leopold, and the new building, which will afford accommodation for the teaching of applhed Chemistry, Physics, and Mechanics, will be finished early in next year. Notwithstanding the inadequacy of the present temporary accommodation, large numbers of students have availed themselves of the instruction afforded. The principles of Hlectric Lighting and Transmission of Power, the making of Electrical Instruments, Coal Tar, and Spirit Distilling have been the subjects that have been chiefly studied during the past session. Since October the classes that were previously conducted by the Artizans’ Institute have been transferred to the Finsbury College. The Institute has under its consideration the establishment of a School for Applied Art in connexion with the Finsbury College. Acting on the general principle that every Technical School of this kind ought to provide, in addition to the general course of instruction, as applicable to different industries, special courses applicable to the staple industry of the district, the Council of the Institute are con- templating the establishment of classes in the Finsbury College adapted to the educational requirements of those engaged in Cabinet- making. With this object it will be necessary to attach a School of Design to the College. The influx of pupils to the studios in Kennington have induced the Council to vote a sum of money for the extension of the building in which the Art School of this district is conducted. These new build- ings are nearly completed, and will afford accommodation for classes in Modelling, Design, and Wood Hngraving. The building of the central institution, which is to be in the first place a school for the training of teclinical teachers, has been com- menced. The first stone was set in July last by H.R.H. the Prince of Wales, who is now the President of the Institute. The plans of this building show accommodation for the teaching of the different branches of Physics in their application to various industries, of Chemistry as applied to trade purposes, and of Mathematics and Mechanics in their application to Hngineering. A good engineering school, containing workshops, well supphed with machinery and collections of mechanical instruments and models, such as exist in numerous Continental cities, seems likely to be obtained for London on the completion of this building. This Institute has done much towards the encouragement of tech- nical instruction in provincial towns, where it is most needed, by its system of annual examinations. In the examination held in May last - 1,568 candidates presented themselves, in 23 subjects, from 115 centres, and of these 895 passed. A close connexion is being established between the several technical schools which are being now opened in Lancashire and Yorkshire, and the City and Guilds of London 60 Anniversary Meeting. [ Nov. 30, Institute. The demands made upon the Institute by Chambers of Commerce in different parts of England satisfactorily imdicate the usefulness of this part of the Institute’s work. The programme of Technological Examinations for 1881-82, just issued, shows 32 subjects in which examinations may be held, some of which are divided into four or five branches, so that they may be better adapted to individual industries. Whilst attention has in this way been given to the details of different trades, the attempt has been made to secure from candidates passing the Institute’s examinations a general knowledge of the principles of their subject and of the relation of closely connected industries with one another. In order to secure in future efficient teachers, the Council of the Institute have determined after March next not to register as teachers any persons except those who have passed the Institute’s Honours Examination, or such as already possess special or distinct qualifica- tions. The interest which the subject of technical education is beginning to arouse has led to the appointment by the Crown of a Commission to inquire into the education of the industrial classes nm England and in other countries; and the City and Guilds of London Institute is represented on this Commission by Professor Roscoe, who, as Presi- dent of the Chemical Society, occupies a seat on the Executive Com- mittee, and also by Mr. Philip Magnus, its director and secretary. The Commissioners are at present engaged in making a tour of inspec- tion in France, a section of them having already visited some of the principal technicai schools and factories in the north of Italy. In Meteorological Science the present year has been marked by the publication of an important work,* by Professor Wild, of St. Peters- burg, on the Temperature of the Russian Hmpire, embodying, in charts and tables, a great amount of information, hitherto either inaccessible or existing only im scattered memoirs, relating to the meteorology of the vast tracts of Northern Asia. As an interesting particular result it may be mentioned that Professor Wild has trans- ferred the “ Siberian pole of cold in winter” from the neighbourhood of Jakuisk to a point somewhat further north, lying on the Arctic Circle in (about) E. longitude 125°. At this centre of maximum cold, round which the isotherms lie in fairly regular ovals, the mean tem- perature in January sinks as low as —54° Fahrenheit, the mean tem- perature at Jakutsk being 11° higher. In close relation to the phenomena exhibited by these charts, Professor Wild, in St. Peters- burg, has been led to study the connexion between areas of permanent high or low mean pressure on the one hand, and areas of permanent high or low mean temperature on the other; and he has found this * “Die Temperatur Verhaltnisse des Russischen Reichs,’ St. Petersburg, 1880. 1881. ] President's Address. 61 connexion to be of the same kind as that known to exist in the case of the shifting areas of high or low pressure, and high or low tempera- ture, which determine the changes of weather. M. Léon Teisserenc de Bort, in Paris, has also investigated the same subject. The Meteorological Office has completed during the year two works of some interest, which are now ready forimmediate publication. The first consists of tables of the Rainfall of the British Isles, prepared at the request of the Council of the Office by Mr. G. J. Symons, F.R.S. These tables include the monthly results recorded at 367 stations in the United Kingdom, being all those for which it was possible to obtain series of observations maintained continuously during the last fifteen years. The second is a volume of charts (with an intro- duction and explanations) illustrating the meteorology of an ocean district specially important to seamen—that adjacent to the Cape or Good Hope. Some points of novelty are presented by the charts. For example, anew form of ‘‘ wind-rose,”’ invented by Mr. F. Galton, F.R.S., has been employed, which offers some theoretical advantages over those previously in use, being intended to represent, with geome- trical precision, the probability (deduced from the observations) that, in a particular place and at a particular season, a wind blowing between any two given points of the compass will be experienced. Again, for the first time in marine meteorology, the wind observa- tions have been ‘weighted’’ with the view of neutralising the tendency to over-estimate the frequency of adverse winds, which has been found to affect meteorological charts injuriously. The work brings into clear relief the most interesting physical feature of the district-—one indeed already well known—the intermingling of hot and cold water, brought by the Agulhas and the South Polar currents respectively, and supplies strong evidence for the belief that this inter- mingling has a large share in producing the atmospheric disturbances so common in the region in which it occurs. In my Address to the Society in 1879, I stated that an Inter- national Conference of a semi-official character had been held, with the view of establishing for one complete year a circle of meteoro- . logical observations round the Arctic regions of the globe. Notwith- standing the lamented death of Lieutenant Weyprecht, the gallant young discoverer of Franz Josef’s Land, by whom the proposal had been originated, it would seem that the efforts of the Conference are likely to be crowned with success. The following stations have already been undertaken by different Governments: Point Barrow and Lady Franklin’s Bay in Smith’s Sound, by the United States ; West Greenland, by Denmark; Jan Mayen, by Austria; Mossel Bay and Spitzbergen, by Sweden; Bossekop, by Norway; Nova Zembla, by Holland; the Mouths of the Lena, by Russia. The Conference has also been led to hope that the Canadian Government may re- 62 Anniversary Meeting. [ Nov. 30, institute observations at Fort Simpson, and that the Government of France may organise a simultaneous meteorological expedition to Terra del Fuego. It is arranged that the observations should begin as soon as possible after August 1, 1881, and should continue to September 1, 1883. In astronomy, Mr. Gill has completed his discussion of the exten- sive series of heliometer measures of the parallax of Mars, which he made at Ascension in 1877, and has deduced the value 8'''78 for the solar parallax, corresponding to a mean distance of 93,080,000 miles from the earth to the sun. A value of the solar parallax has also been derived by Mr. D. P. Todd, from the American photographs of the transit of Venus, 1874. The result for the parallax is 8''883, corresponding to a mean distance of 92,028,000 miles. A valuable contribution towards the determination of the moon’s physical libration has been made by Dr. Hartwig. From a series of 42. measures made with the Strassburg heliometer he derives values for the physical libration and for the inclination of the moon’s axis, substantially confirming the results found by Wichmann, and recently by Professor Pritchard. An addition to the small list of stars which have been found to have a measurable parallax, has been made by Dr. Ball. He finds that the star Groombridge 1618, which is remarkable for its large proper motion, has a parallax of about one-third of a second, so that itis to be considered one of the sun’s nearest neighbours. Dr. Ball has also re- determined the parallax of the double star 61 Cygni, his result being 0'-468, which agrees more nearly with Struve’s value than with Bessel’s. The Cape catalogue of upwards of 12,000 stars is the outcome of Mr. Stone’s labours during nine years, as Her Majesty’s Astronomer at the Cape, and is the most important catalogue of stars which has yet been formed in the southern hemisphere. Another important con- tribution to stellar astronomy has been made by Professor Newcomb, who has recently prepared a catalogue of the places of nearly 1,100 standard stars compiled from the best authorities. In connexion with his photometric researches, Professor Pickering has discussed the causes of the variability of stars of short period. Taking the various hypotheses which have been proposed, he finds that for Algol and stars of that type the hypothesis of an eclipsing satellite or cloud of meteors revolving round the star is the only one which satisfies the observed phenomena. In the case of 8 Lyre and similar variables the fluctuations of light would be explained as due to rota- tion round the axis, the two hemispheres being of unequal brightness and the form more or less elongated. Professor Pickering has very carefully investigated the conditions in each individual case, and has brought together the most important facts bearing on the subject. It 1881.] President's Address. 63 may be mentioned that on Professor Pickering’s initiative a committee of American astronomers has been formed to co-operate with Huropean astronomers in selecting a series of stars to serve as standards of stellar magnitude. The present year has been remarkable for the appearance of two bright comets simultaneously visible to the naked eye. The first comet was first seen in the southern hemisphere before its perihelion passage, and burst upon our view in its full splendour soon after perihelion. The most important point in connexion with this comet was that photographs of its spectrum were obtained by Dr. Huggins and Dr. Draper. The former found on his photographs two strong bright lines im the ultra-violet corresponding to a group in the spectra of compounds of carbon, and also a group of lines between G and h agreeing in position with another carbon-band. The photo- graphs also showed a continuous spectrum extending from F to some distance beyond H, on which the dark Fraunhofer lines were seen— an indication that part of the light from comets is reflected solar light. In the visible portion, the continuous spectrum was so bright when the comet was first seen after perihelion that it almost obliterated the ordinary cometary bands. These, however, became afterwards very conspicuous, and five bands were noted, which were found to coincide sensibly with the carbon-bands as given by the flame of the Bunsen burner. On the brightest band, three bright lines corresponding to three lines in the carbon-band were seen by several observers at Princeton, U.S. These observations show conclusively that the spectrum of this comet is identical with the first spectrum of carbon, and not with the second. In the telescope this comet showed striking changes from day to day, and even, according to some observers, from hour to hour, and the head was remarkable for its unsymmetrical appearance. Another point of interest is that the orbit presents a remarkable resemblance to that of the great comet of 1807. As, however, the period of this latter was found by Bessel to be 1540 years, the question arises again, as in the ease of the comets of 1843 and 1880, whether there are not two comets travelling along the same path. The second bright comet was first discovered with the telescope, and gradually increased in brightness till it became visible to the naked eye, though by no means so interesting an object as the preceding comet. Besides these two bright comets, several telescopic comets have been discovered, raising the total for this year to eight. The last but one of these has proved to be a periodic comet, revolving in the short period of about eight years. It was discovered by an English- man, Mr. Denning, being the first instance of such a discovery in this country for many years. 64 Anniversary Meeting. [Nov. 30, The work of the Royal Commission on Accidents in Mines during | the past year has been of such great interest, both from a scientific and from a practical point of view, that I venture to note at length some notes upon it, furnished to me by our Fellow, Mr. Warington Smyth, the Chairman. A preliminary report was presented before the end of the Session 1881, drawing attention, under the chief heads of the subject, to the facts and opinions elicited from the examination of a large number of competent witnesses. Experimental inquiries, which will be the subject of a further report, have been instituted for the purposes of testing the various safety-lamps in use, as well as the numerous modifications recently proposed, and of determining the effect of coal-dust in causing or ageravating explosions. From time to time, also, experiments have been made with a view to substitute, in the breaking down of coal, some other means for the gunpowder-shots which have so often, by their flame, caused the ignition of fire-damp. The presence of a powerful “blower” of natural gas at the Garswood Hall Colliery, near Wigan, with the facilities offered by the proprietors, induced the Commission to erect suitable apparatus for a long series of ‘these trials, and now that it appears desirable to com- pare the results with what may be obtained in another district, and with a differently constituted fire-damp, the whole of the apparatus is in course of erection at a colliery in the Rhondda Valley, where a very permanent ‘‘blower”’ offers similar advantages. In the course of the lamp experiments it came out very clearly, in confirmation of statements before made, that the greatly augmented ventilation in our larger modern coilieries has put an end to the fancied security of the simple Davy and Clanny lamps. Their use in fact, unless they be protected by some farther contrivance, is attended with the most imminent risk when the velocity of a current lable to be rendered explosive, exceeds six feet a second. A high degree of importance thus attaches to the comparative trials of lamps in which the flame is sufficiently shielded against the impinging stream of air, and those which have the property when immersed in an ex- plosive mixture, of rapidly quenching both the flame of the wick and of the burning fire-damp. The terrible disaster which occurred in September, 1880, at the Seaham Colliery, drew more anxious attention than ever to the question of the part played by coal-dust, and a special reference having been made by the Secretary of State for the Home Depart- ment to Professor Abel, C.B., the experiments at Garswood Hall were largely extended. Some of the results were very remarkable; the proportion of fire-damp present with the air may be so small as to elude detection by the ordinary test of the carefully watched 1881.] President's Address. 65 flame in the safety-lamp, and yet the presence of dust in suspension will cause rapid ignition, or even explosion, in a degree varying with the proportion of gas and the velocity of the current. Dust was employed from different parts of the works of several collieries where it was suspected that this agent had borne a serious part in intensi- fying and spreading explosions; and it was found that some of the varieties were far more sensitive than others. Certain kinds of dust, in themselves perfectly non-combustible, were similarly tested, and proved to have an analogous effect in promoting explosion, even when the percentage of gas was exceedingly small. It is obvious from these facts that under certain conditions it is very important that a satisfactory indicator of minute proportions of fire-damp should be employed; and the further experiments proposed to be carried out by the Commission will include a particular inquiry into this subject. The question of the feasibility of the introduction of the electric light into the workings of a colliery has been partially solved. The Stanton Coal and Iron Company were induced by the Commission to make a trial of Mr. Swan’s lamps in their Pleasley Colliery near Mansfield. Not only the inset and main road, but some of the “‘ long- wall’? faces of work, were brilliantly lighted in this manner. A second experiment of the same kind has been carried out at the Harnoch Colliery near Hamilton. The use and abuse of explosives in mining operations has in the last few years formed a subject of much inquiry, especially with reference to the firing of shots in coal-seams liable to be invaded by fire-damp. A return to mere wedging in all cases, as proposed by some officials, would be to ignore the advance of science as well as the necessities caused by competition; and the Commission hopes by further examination, and especially by practical trials, to contribute useful information to the solution of a difficult but important question. Among the applications of scientific apparatus, the employment of the ingenious protected lime-light lamp, and of the portable breathing arrangement of Mr. Fleuss, during the operations for re-opening of parts of the Seaham Colliery, deserves especial notice. On the motion of Sir Frederick Bramwell, seconded by: Dr. Allman, it was resolved :—“ That the thanks of the Society be returned to the President for his Address, and that he be requested to allow it to be printed.” The President then proceeded to the presentation of the Medals :— The Copley medal has been awarded to Professor Karl Adolph Wurtz, For. Mem. R.S. Professor Wurtz has, for many years past, VOL. XXXIII. F 66 Anniversary Meeting. [Nov. 30, been one of the most distinguished leaders of the progress of chemistry, and is now the most eminent of active French chemists. The younger generation of French chemists were, for the most part, his pupils. His writings have been the medium by which most of the knowledge of the more modern theories of chemistry has been disseminated in France. His discoveries have been fruitful of the greatest results, not merely in the way of enriching the science with a knowledge of many previously unknown compounds and classes of compounds, but more especially in extending and improving our knowledge of the laws of chemical combination. It was he who first discovered compeund ammonias containing alcohol-radicals in the place of hydrogen—a family of compounds which has since acquired enormous development. It was he who first made those remarkable alcohols called glycols, and thus gave the key to the explanation of glycerine, erythrite, mannite, and the sugars. Many other discoveries of his might be quoted; but those who know the influence which these two have exercised on the progress of chemistry can feel no doubt that the author of them is deserving of the highest scientific honour. A Royal Medal has been awarded to Mr. Francis Maitland Balfour, F.R.S. Mr. F. M. Balfour’s investigations in embryology and comparative anatomy have placed him, thus early in life, in the front rank of original workers in these branches of science. His “Monograph upon the Development of EHlasmobranch Fishes,” published in 1878, embodies the results of several years’ labour, by which quite a new light has been thrown upon the development of several important organs in the Vertebrata, and notably of the genito- urinary and nervous systems. More recently Mr. Balfour has pub- lished a most important work on ‘‘ Comparative Embryology ” in two large and fully illustrated volumes, which stands alone in biological literature, not only as an admirable and exhaustive summary of the present state of knowledge respecting the development of animals in general, but by reason of the vast amount and the varied character of the original researches which are incorporated in its pages. A Royal Medai has been awarded to the Rev. John Hewitt Jellett, F.R.S., Provost of Trinity College, Dublin. Dr. Jellett is the author of various papers on pure and applied mathematics; but the award is more directly connected with his invention of the analyser, known by his name, and for the elaborate optico-chemical researches which he has made with it. This analyser was introduced by its inventor into the instrument by which he has carried on his researches on the state of combination of mixed solutions, as evidenced by the changes in their power of rotating 1881.] Election of Fellows. 67 the plane of polarisation consequent upon a change in the propor- tion of the active ingredients which enter into the solution. This is a problem towards the solution of which ordinary chemical methods can contribute but little. A single instance will suffice to give an idea of the nature of the results. It is known that quinine forms with many acids two series of salts, one having twice the quantity of acid of the other for the same quantity of base, while with other acids only the less acid salt has been obtained; so that the ordinary chemical methods fail to give evidence of the existence of the more acid salt. Now, by examining the rotatory power of a solution of a given quantity of base with different doses of acid, Dr. Jellett was able to obtain evidence of the existence of two, and but two, salts of the base, no matter whether the acid were or were not one which yields two crystallisable salts. A slight deviation in the amount of rotation when the more acid salt began to be formed in tolerable quantity, from what it ought to have been, on the supposi- tion that the whole of the acid introduced was combined with the quinine, was naturally attributed to a slight partition of the acid between the base and the solvent, regarded as a feeble base; but the smallness of the deviation indicated that a solution of the more acid salt mainly existed as such, and that it was not, as some had supposed, decomposed into free acid and the less acid salt. The Davy Medal has been awarded to Professor Adolf Baeyer, who was already known as the author of many masterly researches in organic chemistry, among which those on uric acid and on mellitic acid deserve special mention, before his latest and most remarkable discovery. The process for the artificial formation and manufacture of indigo is the result of long-continued efforts, directed by singularly clear and accurate views of the order and mode of combination of its constituent elements, and of the conditions requisite for obtaining reactions indicated by theory. The Statutes relating to the election of Council and Officers were then read, and Mr. Kempe and Mr. McLachlan having been, with the consent of the Society, nominated Scrutators, the votes of the Fellows present were taken, and the following were declared duly elected as Council and Officers for the ensuing year :— President.—William Spottiswoode, M.A., D.C.L., LL.D. Treasurer.—John Evans, D.C.L., LL.D. Professor George Gabriel Stokes, M.A.,D.C.L., LL.D. Michael Foster, M.A., M.D., LL.D. Foreign Secretary.—Professor Alexander William Williamson, Ph.D., LL.D. Secretaries.— ‘ ig 68 Number of Fellows. [ Nov. 30, Other Members of the Council. Francis Maitland Balfour, M.A., LL.D.; I. Lowthian Bell, F.C:S. ; Sir Risdon Bennett, M.D.; Professor Thomas George Bonney, M.A. ; Professor Heinrich Debus, Ph.D.; Alexander John Ellis, B.A.; Sir John Hawkshaw, M.I.C.E.; Thomas Archer Hirst, Ph.D.; William Huggins, D.C.L., LL.D.,; Professor Thomas Henry Huxley, LL.D.; Professor Joseph Lister, M.D.; Professor Daniel Oliver, F.L.S.; Professor Henry Enfield Roscoe, B.A., LL.D.; Warington W. Smyth, M.A.; Henry Tibbats Stainton, F.G.S.; Hdward James Stone, M.A. The thanks of the Society were given to the Scrutators. The following Table shows the progress and present state of the Society with respect to the number of Fellows :— Patron Com- £4 £3 and Foreign. |pounders. yearly. | yearly. Total. Royal. Nov. 80, 1880 .. 4 47 236 D20 25 537 Since Elected .. fay st OL) + 2 ea om Since Compounded + 1/— 1 Since Deceased .. — | ee eh — 24 ee ee ee Nove 30, gsi ey 4 50 227 214 39 034 Financial Statement. 69 1881.] OL € GPe'cs P 8 Lara Cee eeeeoreceence peeeeecsceesvecer ‘“STOSTOD v0) ‘SPT CZCF (73 O OT 8Z9 “ sornquaqog % F AvMTICY PUL[PIPL OOOF JO osvyoang 8 9 O6T paTatatereotavavei tate tavetaisva’ctaveialetateia ciatatelevs eiveieloleVeevelelelsiele sicvalarsielaierereioisiolsiateinlelelnictelelerovsye sosuvyg MUTT 9 CL SI BSOOOOOOOOOIOOIOIOIGIUIIIOOCIOIOIUIC sosuod xqy snoouRlpaost pT Pama ane (o{ Sh = pec: sosivyy Ayjog pur ‘spoorrg ‘osnqysog ONGECe Se ee SuIstywoApy Q GR ittttesessssescsseeeccsneecennsee mel goxeT, 6 I c9eg 0) CT IP nyoluielofele(ere(e(eie(elslsleleleveleieioluie(e(s/sleisje'elafele‘sls\slelvieleiele . 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Professor Cayley, for Apparatus for the Kinematical Construction of Functions of a Complex Variable z+ iy.. 50 0 0 R. H. M. Bosanquet, for Balance of the cost of an Engine with Clock, Bellows, and other Applances to be em- ployed in the Solution of various Problems in Acoustics.. 99 5 3 Professor W. G. Adams, for the Expense of procurmg Photographs of Magnetic Tracings from various Obser- vatories over the Globe, and for assistance in comparing and examining them, so as to arrive at a more exact know- ledge of the Laws of Terrestrial Magnetism ............ PAO Or 0) A. Mallock, for completing the construction of the Room for the Diffraction Grating Ruling Machine ...... 30. OF Rev. A. H. Haton, to defray further the cost of Printing and Publishing a descriptive Monograph of the Hphemeride 120 0 0 G. E. Dobson, for an Examination of the Anatomical Structure, Systematic Position, and Geographical Distribu- tion of the Species of the Order Insectivora, to be pub- lished in the form of a Monograph, illustrated with plates fromoricinal drawings oy the Author) Fe. ...-- eee eee MOH Oo D. J. Hamilton, for a Research into the Topographical Anatomy of the Central Nervous System studied in rela- LIOM LOWS elavStOlOGY ~ le cieson- |e c1- es leegelel eee a ae 50 0.70 A. Frazer, for Apparatus for a Series of Experiments on Wind Pressure. (1) Rate of variation of pressure on dif- ferent sized plates. (2) Pressure on perforated plates, and wire gauze disks. (3) Lifting power of air currents.... 25 0 0 SE aEREEEEEEnEEeEeeeRED O74) oume Dr. Cr. CaS ids {sie To Balance on hand, Nov. 30, By Appropriations, as 1880. . seveesccccsssee DIVZ 18 2 |c above... .... 7.1 hemmed aime Grant froin Treasory, 1881 .... 1,000 0 0 | Printing, Postage, and Repayment .. Bide bo loeD aoe 11 7 4 Advertising ...... 814 0 Balance on hand, Nov. 30, 1881 ........5. L446 Gis £2,129 5 6 £2,129 5 6 1881. | Appropriation of the Government Grant. G Account of Appropriations from the Government Fund of £4,000 made by the Lords of the Committee of Council on Educa- tion, on the recommendation of the Council of the Royal Society. 1880-81. G. F. Rodwell, for continuation of his Experiments on the Anomalous Coefficients of Expansion of certain Iodides, Chlo- 208, alba) [BO Ghana £30 A. Macfarlane, for extending his Researches into the Disrup- FigesWiceharge Of HICCtriCiby «6. 1.4065 oe one can fo seme sess 50 Professors Liveing and Dewar, for apparatus and materials required in continuing their Spectroscopic Investigations...... 200 J. N. Lockyer, for continuation of Researches on the Solar STEEL op SoS She PERS Oe Oe ee ee 150 R. S. Marsden, for development of a new Theory for the Hardening of Steel, with special reference to the State of SL I0TL 1 SUCELS 5 aac Ie a mel ae ae laa ene near 15 J. Parry and A. HE. Tucker, for aid in continuing Experiments on the application of the Spectroscope to the Analysis of Iron HL, STEEL co oe URS BREE ee a ea Ree 106 A. Tribe, for continuation of Ressurchios into Electric Distri- bution as manifested by that of the Radicles of Electrolytes .. 75 W. Crookes, for assistance in continuing Researches in Mole- oiler [Pansies Dye) 0) A/C eee eee ere 200 Dr. T. Carnelley, for a Research on the Action of Heat on Substances under diminished Pressure, and the existence of Ice and other Bodies at Temperatures above their ordinary Melting SR PEE hae alec se 6 565040 ed elas emcee ce dens 10¢ Professor W. N. Hartley, for payment of an Assistant, and the cost of Materials and Apparatus employed in his Investiga- tions of the Ultra-violet Rays of the Spectrum .............. 100 Professor O. J. Lodge, in aid of Researches, more especially into the Action of Light on the Conductivity and Residual Charge Phenomena of Glass and Electrolytes................ 100 Professor R. Grant, for the Expense of Printing a Catalogue of the Mean Places of 6,350 Stars, based on Observations made mpc laswow Observatory 6.0... 5.22. ese oc eee ne ec epemyon 300 J. Glaisher, towards the Expense of Printing the Factor Table 25 Ube NSibeialay gE Nort, ie 2 we See arc a ee ee Oe cr a 150 R. McLachlan, in aid for continuation of his Researches on Pucepean Urichopterous Insects ............6.2esecte- eee 25 Carried rorwalds.. Ncw eeee see £1,595 18 . Appropriation of the Government Fund. [Nov. 30, Browehit tomwands oem <\ ol els £1,595 Professor Duncan and P. Sladen, for the cost of an Additional Plate (Comatule) in their Monograph on Arctic Echinodermata Professor Heddle, for continuation of a Research connected with the Scientific Mineralogy and Geognosy of Scotland: £100 for Analyses, and £100 for personal expenses in collecting SCCIMENS Gs saa 5.) viku eee ERR So 5 HK. C. Rye, in aid of the Publication Fund of the Zoological Record Association -.. 2 oi at. crrslewteusraieisvelmp esse leeks Seca ee Dr. R. Braithwaite, for aid in publishing a work. on the Satish Moss Mlora i7.\.c\osp cn cle epacuaee cree os oe. eer D. Mackintosh, for continuation of his Search for High Level Gravel and Sand with Marine Shells along the Northern and Kastern Slopes of the Welsh Mountains, and along the Western Slopes ofthe Pennime Elills . 2.4.7 fe wees o eee eee Professor Nicholson and R. Etheridge, jun., for Further As- sistance towards the Publication of the Third Fasciculus of their ‘Monograph of the Silurian Fossils of Girvan, Ayrshire” .... J. N. Langley, for an Investigation into the changes which take place in the Gland Cells of the Liver and Kidney during SGCTEHION. 2 ocak ck ood ow alten eioae eects Si J. S. Gardner, for assistance in working out more systemati- cally than has yet been done, the Mull, Antrim and Iceland Mertiary Plant Beds |. a 2% cs acces one’ el she Mo eee Professor W. T. Dyer, for aid in the preparation of an illus- trated Monograph of Cycadwa-...... 5. ...52, shee HK. A. Schafer, for payment of an Assistant in continuing his Histological and Embryological Investigations .............. Dr. G. Thin, for investigation of the Epithelium, and of the Lens and Retina in the Tadpole, and the Influence of Light on the Development of fhe Tadpole .:.. ..i0-.0.:.a0 ee eee Rev. J. F. Blake, for aid in preparing and publishing 4 work on British Wossil Cephalopoda ...< +. 42 -1-<- 02-11 eee Dr. F. R. Japp, for an Investigation of the Reactions and De- compositions of the Quinones; with a view to throw light on the constitution of this Group of Compounds, and indirectly upon that of the Benzene Series generally ............seeee C. F. Cross, for materials to be used in the Extension of his Research into the Rehydration of Metallic Oxides............ J. H. Collins, for continuation of Chemical, Mineralogical, Microscopical, and Stratigraphic Observations on, and Investi- gations of the Rocks of Cornwall. . 22)... ----/. - - «47 eee Dr. C. R. A. Wright, for continuation of Researches on the 10 200 100 50 20 100 30 150 20 50 25 100 50 10 Carried forward... <5..02.) eee £2,540 1881. ] Appropriation of the Government Fund. 79 Broucht torwardstss-<-.-. eee coo .O AU) Determination of Chemical Affinity in Terms of Hlectromotive LIPS cco Be EDI Cle 0.0 Ot OO COE Ln an eee ana Pa 200 C. E. Groves for Researches into Lichen Products and Deri- vatives obtained from Naphthalene now in progress, originally undertaken in conjunction with the late Dr. Stenhouse........ 200 R. Etheridge, jun., and P. H. Carpenter, for the Preparation of a Monograph of the Blastoidea, especially of British Species, MPRME RC UIs WVEOROMOIOR VE oe 565 6 5 joes: cee aleis s6 eet oan see aes 60 Dr. Fraser, for a Research on the Action of Medicines on the meaneanasteripheral Circulation... 26. sscas 6 ojo 6.06 6 eons eo oe 30 HK. Neison, for continuation of Computations in the Lunar VME eres eo S506 ah sakes Gh Oi iare si aS vlefala siel dle thej eke s 5 dele’ 5) Dr. G. Gore, for Investigation of the Phenomena of Electric Osmose, the production of Hlectric Currents by Liquid Diffu- sion, and (probably) the Transmission of Electric Currents by LACTEICS! co co oe BS eRe IO IAI CRP a ane Oe ean ann 100 H. Tomlinson, for his Researches on the Influence of Stress ameesurac on the Action of Physical Forces ....'............ 100 Rey. J. Henslow, for Physiological Researches on the Trans- piration of Plants, the effect of Coloured Light thereon, and to discover the different nature of Coloured Leaves La means of the “NSPE GOODS c Bb IDC OS CII ae I Ar oe Poe 50 W. K. Parker, for assistance in his Researches into the Mor- pereerrmeia MeV CILCDTA LA. 54: lita sxe © niger gaayeA «9405.4: on sh ele 300 F. O. Bower, for a Research into the Minute Histology of Plants, more especially of Welwitschia mirahilis .............. 100 W. Saville Kent, for the further prosecution of Investigations into the Structure and Life History of certain Lower Protozoa.. 100 C. Lapworth, for Investigation of the Lower Paleozoic Rocks of Scotland, and of the Family of the Graptolites ............ 80 Spencer U. Pickering, for a Research into Molecular Combi- om MERE hte Aa3=. ais) 4 lS Ws seid a osad «le od dibyarelsi oor wings 50 £3,985 Administrative Expenses ............ hoe coc creo ce 15 Report of the Kew Committee for the Year ending October 31, 1881. The operations of the Kew Observatory, in the Old Deer Park, Richmond, Surrey, are controlled by the Kew Committee, which is constituted as follows: General Sir EH. Sabine, K.C.B., Chairman. Mr. De La Rue, Vice-Chairman. | Vice-Adm. Sir G. H. Richards, Capt. W. de W. Abney, R.E. C.B. Prof. W. G. Adams. The Earl of Rosse. Capt. Sir F. Evans, K.C.B. Mr. R. H. Scott. Prof. G. C. Foster. Lieut.-General W. J. Smythe. Mr. F. Galton. Lieut.-Gen. R. Strachey, C.S.I. Mr. E. Walker. Lieut.-Gen. Sir J. H. Lefroy, K.C.M.G., having been appointed Deputy-Governor of Tasmania, withdrew from the Committee in December, and Capt. Abney was elected to fill the vacancy. The work at the Observatory may be considered under seven heads :— Ist. Magnetic observations. 2nd. Meteorological observations. 3rd. Solar observations. 4th. Experimental, in connexion with any of the above depart- ments. 5th. Verification of instruments. 6th. Aid to other Observatories. 7th. Miscellaneous. I. MaGnetic OBSERVATIONS. On January 10 the magnetograph needles were dismounted and re-magnetized, having become weakened by age. Since then work has continued as usual. The scale values of all the instruments were re-determined in January, in accordance with the practice of previous years, both before and after the re-magnetization of the needles. Report of the Kew Committee. 81 The following are the values of the ordinates of the various photo- graphic curves :— Declination 1 inch = 0° 2204. 1 mm. = 0° 087. Bifilar Jan. 4, 1881, for 1 inch dH=0°'0739 foot grain units. » Lmm. , =0:001384 mm. mer. units. » van.12,1881 ,, linch ,, =0-0442 foot grain units. , Lmm. ,, =0°'00080 mm. mer. units. Balance Jan. 7, 1881 ,, 1 inch dV=0-0648 foot grain units. power O00 1 Lm. mer, units: » gan.14,1881 ,, Linch ,, =0-0323 foot grain units. 3k mm. 4, =0'00059 mm, mer. units: Two magnetic storms, or periods of considerable disturbance of the needles, have been registered during the year; one on the night of January 3lst, and a second on September 12th and 13th, both being accompanied by brilliant auroral displays. The monthly observations with the absolute instruments have been made regularly, and the results are given in the tables forming Appendix I of this Report. Professor W. Grylls Adams has during the year continued his in- vestigations on the comparison of magnetic disturbances in various localities. In addition to the curves mentioned in last year’s Report, he has received through the Committee several supplies of copies of selected traces from Mauritius, Toronto, and Zi-Ka-Wei, near Shanghai, as well as from those Observatories already enumerated in the last report. Professor Adams has embodied the results of his researches in two papers read before the British Association, and in a Friday evening lecture delivered at the Royal Institution. The discussion of the great magnetic storm of January 31st, 1881, having been undertaken by Dr. H. Wild, of the Central Physical Observatory, St. Petersburg, such particulars respecting that occur- rence as the Committee possessed were transmitted to that gentleman. The magnetic instruments have been studied, and a knowledge of their manipulation obtained by Lieutenant Moore, R.N., Dr. Brauner, and Dr. Monckman. Information on matters relating to terrestrial magnetism and various data have been supplied to Professor W. G. Adams, Dr. Atkinson, Dr. Buys Ballot, Mr. Gee, Mr. J. EH. H. Gordon, Rev. F. Howlett, M. Mascart, Dr. Miller, Professor Balfour Stewart, and Dr. Wild. The following is a summary of the number of magnetic observations made during the year :— Determinations of Horizontal Intensity........ 29 [dice 3 aR ie eRe Tas 160 . Absolute Declination........ 43 VOL. XXXIII. G 82 Report of the Kew Committee. IT. METEOROLOGICAL OBSERVATIONS. The several self-recording instruments for the continuous registra- tion respectively of, atmospheric pressure, temperature, and humidity, of wind (direction and velocity), sunshine, and rain have been main- tained in regular operation throughout the year. The standard eye observations made five times daily, for the con- trol of the automatic records, have been duly registered through the year, together with the additional daily observation at 0h. 8m. p.m. in connexion with the Washington synchronous system. The 6h. 45m. P.M. observation, for the second synchronous system organized by M. Mascart, Directeur du Bureau Central Météorologique, Paris, was discontinued on December 31st. The tabulation of the meteorological traces has been regularly carried on, and copies of these, as well as of the eye observations, with notes of weather, cloud, and sunshine have been transmitted weekly to the Meteorological Office. The following is a summary of the number of meteorological obser- vations made during the past year :-— Readings of standard barometer .............. 1929 “ dry and wet thermometers........ 7508 es maximum and minimum thermo- meters’. . ct’) 4,06) pee oe eee ee 2190 ‘ radiation thermometers .......... 750 = Tain Pauses 2s ss. ees eee eee 730 Cloud and weather observations .......-...ee. 2294, Measurements of barograph curves............ 9125 3 dry bulb thermograph curves.. 9125 - wet bulb thermograph curves.. 8986 x. wind (direction and velocity).. 17320 ee raintall CUrves ..... oseeckee s failed 5 sunshine traces 2 cxac see eee 2149 In compliance with a request made by the Meteorological Council to the Kew Committee, the Observatories at Aberdeen, Armagh, Falmouth, Glasgow, Oxford (Radcliffe), Stonyhurst, and Valencia, have been visited as on former occasions, and their instruments inspected by Mr. Whipple during his vacation. With the concurrence of the Meteorological Council, weekly abstracts of the meteorological results have been regularly forwarded to, and published by ‘‘ The Times,” “The Illustrated London News,” and “The Torquay Directory,” and meteorological data have been supplied to the editor of ‘‘Symons’s Monthly Meteorological Magazine,” the Secretary of the Institute of Mining Engineers, Messrs. Buchan, Eaton, Greaves, Gwilliam, McDonald, Rowland, and others. Report of the Kew Committee. 83 Electrograph.—This instrument has been in continuous action through the year, with the exception of a few occasions during the severe frost of last winter. In July the instrument was Tee oantauh and a fresh supply of acid placed in the jar, the charge-keeping properties of which had become slightly deteriorated. The tabulation of the curves given by this instrument has at last been commenced, and a suitable glass scale, arranged on a plan devised by Mr. Whipple, having been constructed by Mr. Baker, the average hourly tension of atmospheric electricity at the collector of the Electrograph has been determined for every hour in 1880, except in those cases where registration failed either from disturbance or instrumental defect. From these values the daily, monthly, and annual means have been deduced, together with other facts bearing on the relations existing between atmospheric electricity and different meteorological phe- nomena. Some results of this investigation were by permission of the Meteorological Council submitted by the Superintendent to the Meeting of the British Association at York, in a paper which has since been ordered by the General Committee to be printed in extenso among their Reports. The expense of the tabulation was defrayed by a special grant from the Meteorological Council. III. Sonar OBSERVATIONS. The only solar work done at Kew during the past year has been the regular maintenance of the eye observations of the sun, after the method of Hofrath Schwabe, as described in the Report for 1872. These have been made on 187 days, in order to preserve the continuity of the Kew records of sun-spots. The sun’s surface was observed to be free from spots on three of those days. A small portable 22 in. refracting telescope, with a magnifying power of 42 diameters, is used by the observer. Transit Observations.—Ninety-four observations have been made of sun-transits, for the purpose of obtaining correct local time at the Observatory: 126 clock and chronometer comparisons have also been made. In addition to these a considerable number of star transits have been observed in connexion with the pendulum operations in progress during the autumn of 1881. TV. EXPERIMENTAL WORK. Winstanley’s Recording Radiograph.—This instrument, designed for the purpose of registering continuously the amount of radiation from the sky, by mechanical means, upon a sheet of blackened paper, still G2 84 Report of the Kew Committee. remains at the Observatory, but having been accidentally deranged, it has not been at work for some months. The inventor being abroad it has not been possible to place it in re-adjustment. Nephoscopes.—Experiments have been made with several forms of nephoscope designed by Mr. F. Galton, and also with a new cloud- camera, designed by the Superintendent. Exposure of Thermometers.—Hxperiments have been continued throughout the year at the Observatory, with the view of determining the relative merits of different patterns of thermometer screens. For this purpose there were erected in 1879 on the lawn a Stevenson’s screen, of the ordinary pattern, and a large wooden cage, containing a Wild’s screen, of the pattern employed in Russia. Hach of these screens contains a dry and a wet bulb thermometer, and a maximum and minimum, all of which are read daily at 9 a.m. and 9 p.., their indications being compared with those of the thermograph at the same hours. A third portable metal screen, designed by Mr. De La Rue for use on board Light-ships, which contains a dry bulb thermometer only, is also carried into the open air by the observer, and read at the same time as the fixed instruments. The cost of these experiments is borne by the Meteorological Council. Glycerine Barometer.—This instrument, devised and erected by Mr. Jordan, has remained in successful operation throughout the year. In compliance with the request of the inventor, it has been con- tinuously observed five times daily, in conjunction with the mercurial barometer. Mr. Jordan has been supplied with copies of the observations, but — the Committee have not yet, however, been informed of the results of these comparisons. Pendulum Heperiments.—In March, the Committee received a communication from the Council of the Royal Society, calling their attention to the fact that the invariable pendulums deposited in the Loan Collection of scientific instruments at South Kensington, could not be considered as in the custody of the Committee, and in conse- quence the Science and Art Department was requested to return the instruments to the Observatory. They were accordingly received on the 15th of June. Subsequently an application was received from Major Herschel, R.E., F.R.S., by authority of the India Office, for permission to make certain experiments with the pendulums, and for the loan of the instruments, with their accompanying appliances, with facilities for prosecuting the experiments at the Observatory. These requests were granted, and since the beginning of September operations have been continuously carried on, both in the Pendulum Room and in the Experimental House at Kew. Report of the Kew Committee. 85 The Indian Government will defray all expenses that may be in- curred in the prosecution of the experiments. V. VERIFICATION OF INSTRUMENTS. The following magnetic instruments have been verified, and their constants have been determined :— A set of Self-recording Magnetographs for the Nice Observa- tory. A Unifilar Magnetometer for Casella. Three Dip Circles for Casella. A pair of Dipping Needles for Elhott Brothers. There have also been purchased on commission and verified :— A Unifilar Magnetometer and Dip Circle for Professor Tacchini, Rome. A Unifilar Magnetometer and Dip Circle for Professor Perard, Liége. A Dip Circle for Capt. Hoffmeyer, Copenhagen. A Dip Circle for Professor Malmberg, Stockholm. A Pair of Dipping Needles for the Colaba Observatory. A Dip Needle for Senhor Capello, Lisbon. The number of meteorological instruments verified continues still to increase, having been in the past year as follows :— isarometers oinaard ONL, MO. Sh OU eg. ails.’ 59 “F Marine and Station............ 109 PUAERGIOSS ULE Sakis o Se NS Alaa t eked 34 ated ayeghe bt - S 679-66 | 66T- ~ OSZ-66| GGT. SS 869.62 | ZPzS ‘> | 82-62] zz. i 669.66| 89. oy “SsoTOuUl “Your = RS "a1e | WOTStIOy Arq |-tnode 4. “SUVOTIT “OANSSOL LPV-66 GLE.6G VOPV-66 EEV-66 OLP-66 SP9-66 VEL-66 VI6.8¢ 898-82 TL0-62 BEL.8z LOL.86 solourL “IV are oy th 64 ‘NVE 92 ‘Wag TE (74 F 9 ‘NV > OL BESS oa OY giierdi Gey), ‘NV G LIL CGS =. -8— 66 Wd2e oO! ‘WV OL 82 aul 99 OUR “TANUIUTUL OULO.L4X FL f° LOZOULOLV O&V-0& 6V8-0E 9€6-0€ GEs-0€ 089.0€ OL6-0& $9G-0§ ee ee (Bo hy ‘[UAQnop yeyAotos suvow ATrep oy Jo oug f “PUNOIG OY} CAOGL 409} OT Lt Sq[NG-LoJoULOUMAOY OUT, » ‘[LOUNOD [VOLSOTO.L09}0 TT —_——— ee — — ——SeSSSeSeSeSeSe ee OTheg P86-62 VS8-66 “6 TL |'F00-08 ‘WV € O& | 86-62 ‘Wd II O! 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XXXIII. ‘ydeasouous oy q poaoqstsoa sy tf ‘Wd OT pur “p ‘Z ‘uoou “H'V OT 4B OPVUT SUOTYVALOSGO TOIT POALIO, \. Cielo a8) oe 1) 6 | ye ee gs L v v z i S v 9 6 OU | Le ts H Nore € 9 Or) 3 g ata I 4 S z 9 6 g I z g € eS g @ Oita ees Pet i L G § s € € v id I g OL | & 5S z OK | 8 G r 8 if I Ss § G i & Ui G G ¢ = | v v z T 9 4 g S = g 6 le I I j z G Ir | 8 T I v g 3 v v v I z el | & iS ee = Pee ANAS |S | S| @ | aN | “N YS MOTY JL POIYM WO skvp Fo coquinyy “f purpd 98 PL 14 T om me LT ST T § rr i LT 6 6 T i a §T PL A A T ~ et cL 8 3S il qe OT (el ic T T eft 6 VL 9 T G G 6 ez Ae ay oF ip TT 8I g af gs S| 9 GG G ess ae g €T PT G ie as ait CT 0G T x a G 8T ACTS at | une bas "SULLO4S . . qsvo | | -top | ‘Tle |*Moug | ‘uresy pid eda) -L0A QC) 10 | a / | 7 S , Z ‘ 7. V ‘ ria / c ‘ ‘ 7) : / r¢ rd ‘ \ Ton co f 5 5 ea! RSes \i ie oS 7 The annexed diagrams show the relation of the course of the intestine in Culeolus to the arrangement found in Ascidia. The chief difference is that in the latter genus the intestine, after running posteriorly for a short distance, takes a final curve anteriorly, thus making a second loop (2), open anteriorly, which is entirely wanting in Ouleolus. 'The cause of the difference is obviously the position of the atrial aperture (A?.) This hes in Culeolus almost at the posterior end of the body, and con- sequently the last part of the intestine runs posteriorly. In Ascidia, on the other hand, the atrial aperture is usually situated near the anterior extremity, therefore the intestine is necessarily twisted for- wards again so that it may terminate near the common excretory aperture. All the species of Culeolus are from upwards of 600 fathoms; five are from over 1,000 fathoms, four from over 1,500, and two from up- wards of 2,000 fathoms. They all belong to the abyssal fauna. It is noteworthy that these six species, the only deep-water Bol- tenine, all belong to one genus, notwithstanding their wide distribu- tion in space—one species being from the North Atlantic, two from the Southern Ocean, one from the South Pacific, one from the North Pacific, and one from the centre of the Pacific Ocean on the Equator. 1881.] Development of the Skull in Lepidosteus osseous. 107 I. “On the Development of the Skull in Lepidosteus osseous.” By W. K. PARKER, F'.R.S. Received November 3, 1881. (Abstract. ) The materials for the present paper were kindly sent to me by Professor A. Agassiz; they were for the use of Mr. Balfour and myself, and consisted of fifty-four small bottles of eggs and embryos in various stages. These very valuable materials were obtained from Black Lake by Mr. 8S. W. Garman and Professor Agassiz, and many of the embryos were described and figured by the latter in the “Proceedings of the American Academy of Arts and Sciences,” October 8, 1878. Having received from my friend the author a copy of his im- portant paper, I at once wrote to ask permission to work his materials out, thoroughly; suggesting that Mr. Balfour would under- take the embryological part of the work. On receipt of my letter Professor Agassiz kindly acceded to my wish, and the results of our investigations are now ready for publi- cation. Mr. Balfour’s part of the work has been done with the assistance of my son, Mr. W. N. Parker, and their joint labour will include the anatomy of various organs of the adult fish. We have had additional materials from Professor Burt G. Wilder; these were larger young than those supplied by Professor Agassiz ; Mr. Balfour also has obtained several adult fishes in spirit; and I am indebted to Professor Flower for an adult in the dry state. Finding that we were in a condition to do some useful research on. this important Holostean Ganoid, I pressed Dr. Traquair to take up the skull of the adult ; this he consented to do; and I am daily ex- pecting that his paper will be sent to the Royal Society. My observations on the skull and visceral arches have been made on embryos and young, varying from one-third of an inch to 43 inches in length; I have (artificially) divided these into six stages. Cartilage was being formed in the smallest examined by me, but in my second stage, embryos five-twelfths of an inch long, this tissue was quite consistent, and I succeeded in dissecting out all the parts. The large notochord at this stage bends downwards under the swelling hind- orain, and then turns up a little at its free end; passing into the lower part of the fissure between the mid- and hind-brain, it reaches beyond the middle of the cranium, and just touches the infundibulum and distinct pituitary body. The paired cartilages, “‘ parachordals,”’ that invest the notochord only cleave to its hinder three-fifths; these bands then diverge and 108 Mr. W. K. Parker. [(Deens. enclose a Janceolate space under the fore-brain (‘‘thalamencephalon’’). These somewhat flattened bands of cartilage become narrower up to the middle of this large primary “ pituitary space,’ and then recover their former width in front, where they come in contact, having no notochord between them. All the cartilage that lies in front of the notochord is called trabecular; between the trabecule, in front, there is a small wedge of younger cartilage, the rudiment of the “inter- trabecula.’’ The hinder, or parachurdal, parts are somewhat scooped and bevelled above, and on their edge the auditory capsules rest. These are quite distinct, and have a cartilaginous coat, which, however, has a large oval deficiency below. As in the Batrachia, the fore part of the ‘‘ palato-quadrate”’ cartilages is continuous with the trabecule in front; but the ‘‘pedicle” is free behind. The free ‘“articulo- Meckelian ”’ rod is quite in front of the eye-balls, and is nearly as long as the hind suspensorium, or proper quadrate region; this forward position of the hinge of the mandible is not temporary as in the frog, but is permanent. The uppermost element of the hyoid arch is an anvil-shaped cartilage from the first, and ossifies afterwards, as the hyo-mandibular and symplectic bones. As pointed out to me by Mr. Balfour, its dorsal end is continuous, as cartilage, with the skull (auditory capsule) above. The basi-hyal is not yet ossified, but distinct inter-cerato- and hypo-hyal segments are already marked out. Four larger and one small rods of cartilage are seen on each side, articulating with a median band; these are the branchial arches, which chondrify before they undergo segmentation. In this stage there are no osseous lamine as yet formed. Here, in this stage, in connexion with a large pre-nasal suctorial disk, we have three important generalised characters, namely, the continuity of the distal end of the mandibular pier and of the proximal end of the hyoid pier with the skull, and the forward position of the hinge of the jaw coupled with the horizontal direction of the suspen- sorium. The hyoid arch has its segments formed much earlier than in the Teleostei, and the “ pharyngo-branchials” are not independent cartilages, as in the Skate. The third stage—embryos two-thirds of an inch long—show a con- siderable advance in the development of the skull; the cartilage, generally, is more solid and more extensive, and new tracts have appeared. The apex of the notochord is now in the middle of the basis craniil, for the prochordal tracts have grown faster than the parachordals. The large so-called pituitary space is now irregularly pyriform, and not lanceolate: the fore margin of the broad para- chordal bands being now nearly transverse, whilst the prochordals (trahecule) are wide and fenestrate at first, then narrow, and then widening suddenly, they coalesce, forming a sharp anterior end to the pituitary space. 1881.] Development of the Skull in Lepidosteus osseous. 109 Behind, the parachordals have grown further along the thick noto- chord, and on each side they are now confluent with the auditory capsules, which have become irregularly ovoidal through the growth of the large semicircular canals within; their basal fenestra is still a round space under the partially floored ‘‘sacculus.” The trabecule swell out where they are confluent, and then are narrower in front again. At their fore end each band passes insensibly into the corre. sponding palato-quadrate bar outside, whilst inside they are separated by a large pyriform wedge of cartilage, the intertrabecula. The thick, rounded, free fore end of this median cartilage is the rudiment of the great “nasal rostrum,’ and the rounded fore ends of the trabeculee are the rudiments of their “‘ cornua.” There is only a floor in the occipital region, but the wall-plate of the chondrocranium has begun as a styloid cartilage running forward from the fore end of each auditory capsule into the superorbital region. The palato-pterygoid band—continuous in front with the trabeculee— is now longer than the proximal part of the suspensorium, the spatulate quadrate region whose dorsal end is the free “pedicle.” The wide proximal part of each trabecula is now already forming an oblong facet, the ‘‘ basi-pterygoid,” for articulation with the facet of the “‘ pedicle.” An oblong concavity is now seen under the outer edge of each auditory capsule, for the oblong head of the hyomandibular whose body is still solid, and the “‘ symplectic” part merely a process growing downwards and forwards to get inside the lower margin of the sus- pensorium of the mandible. The epi-hyal region is still merely the top of the cerato-hyal; it is afterwards separate as a bony centre; the inter-hyal, hypo-hyal, and double basi-hyal are all now chondrified and distinct, but the branchial arches are not yet segmented. In this stage the skull is a curious compromise between that of a Salmon at the same stage and that of a Tadpole just beginning its transformation. The hind-skull is quite ike that of a young Salmon, the fore-skull, with its non-segmented palato-quadrate, and its forwardly placed quadrate condyles and horizontal suspensorium, is very much like what is seen in the suctorial skull of the Anwrous larva; a splint bone, ‘the parasphenoid, as in the Tadpole, has now made its appearance. The largest embryos reared by Messrs. Agassiz and Garman, which are about one inch in length, form my fourth stage; these are rapidly acquiring the characters of the adult. This is the stage in which the chondrocranium of this Holostean type corresponds most closely with that of the Chondrostean Sturgeon, whose adult skull is similar to that of Garpike just as the latter begins to show its own special characters. This important difference is already evident, namely, that whilst in Acipenser the olfactory capsules remain in the antorbital position, those of Iepidosteus are already carried 110 Mr. W. K. Parker. [Deess., forwards by the growing intertrabecula, and are even now in front of the relatively huge “‘cornua trabecule.” Thus these regions are now well grown in front of the ethmoidal territory, which, instead of being, as in the last stage, in the front margin of the skull, is now fairly in its middle, and this change has taken place whilst the embryo has only become one-half larger—from two-thirds of an inch to an inch in leneth. It is the hypertrophy of cartilage in the three trabecular tracts. that makes the “rostrum” of the Sturgeon so massive, even whilst only a few inches in length, and this state of things exists temporarily in the Garpike. Each “cornu” is now like a thick succulent lanceolate leaf, coiled. partly upon itself, downwards, at its outer edge; the middle bar, or intertrabecula, is now half as long as the skull, and projects forwards beyond the cornua, and between the distally-placed olfactory capsules. The cranial cavity is now relatively very large, and is covered by a cartilaginous “‘tegmen,” before and behind; between these regions,. over the huge mid-brain, there is a sub-circular “‘ fontanelle,” narrower in front than behind, and emarginate in front by some growth of cartilage in the mid-line. The postorbital spike of cartilage has now grown into a narrowish superorbital band, bounding the upper fontanelle and enclosing between itself and the trabecula, below, a large “ orbito-sphenoidal ” fenestra. The floor is also still open, and this large pituitary space 18: spearhead-shaped, and is under-floored by the parasphemordl The basipterygoid processes are now well formed; the basal carti- lages (parachordals) now embrace the huge wohoehond below, the flaps. approaching, but not touching, each other. The notochord is now being formed into a ‘‘ cephalostyle,”’ but the bony sheath is imperfect. Above, the sphenotic, epiotic, and opisthotic projections of the auditory capsule are more evident, but are not ossified. Some slight bony deposit has appeared in the prootic region. The “‘cephalostyle ” is the first endo-cranial bone, and the parasphenoid the first ecto-cranial centre ; but the exoccipitals are just appearing also. The condyle of the quadrate is now still further behind the middle of the palato-quadrate arcade, the pterygopalatine part of which is now quite free in front, and. has grown forwards parallel with the rostrum, as a long style, which reaches further forwards than the cornua trabecule. The “pedicle” of the suspensorium has a facet by which it articulates with the basipterygoid. The mandibular cartilage has also grown equally with the freed pterygopalatine rod, and has now a very lane ear-Sshaped coronoid part in front of and above the articular part. The opercular process and fenestra of the hyomandibular are now formed, but this. part is not ossified; the cerato-hyal diaphysis is present. It is the only shaft-bone in the hyoid arch as yet; the branchial arches are seg- menting. The superficial bones can now be seen as fine films in the 1881.] Development of the Skull in Lepidosteus osseous. AT iL transverse sections, and the parosteal palatine and pterygoid are large leaves of bone applied to the pterygopalatine bar; the mesoptery- goid is only half as large as them, but is relatively much larger than in the adult. Whilst doubling its length, the young Lepidosteus gains a cranium much more like that of the adult; this is my fifth stage. The general form is now intensely modified by the foregrowth of the rostrum: the ‘‘intertrabecula ” is now two-thirds the length of the entire skull. The cornua trabecule now reach only two-fifths of the distance to the end of the beak, and the pterygopalatine arcade reaches but little further forwards. Owing to the ‘‘tegmen cranii” being much larger, the upper fontanelle is much smaller; it is now a-short oval, its longer diameter being lengthwise. The bony matter of the “‘ cephalostyle ” is now aggregated towards the hinder half of the notochord; it is now the basi-occipital bone. The exoccipitals and prootics are growing larger, and there are now both sphenotics and alisphenoids. Also, below, the quadrate, metapterygoid, and articular ‘‘centres”’ have appeared; and behind the jaw there are the hyomandibular, sym- plectic, epi-hyal, cerato-hyal, and hypo-hyal centres; and the epz-, cerato-, and hypo-branchials have acquired a bony sheath. In a young Lepidosteus 44 inches long (nearly), the approach to the adult state of the skull has been very great; the superficial bones can all be determined. The most remarkable of these are the small distal nasals and premaxillaries; the long mawillary chain, ending in an ‘‘os mystaceum and jugal”; the extremely long and slender “‘ethmo-nasals”’ and vomers; the small pre-opercular; and the huge angulated inter-opercular, which carries the large opercular and sub- opercular. The five mandibular splints are all present (as in most Sauropsida), the branchiostegals are only three in number, as in the Carp tribe. The intertrabecula, which was merely a small tract of cells binding the trabeculee together, in front, is now three-fourths the length of the entire skull; to it is due the length of the beak. The cornua trabecule are now merely short lanceolate leafy growths on the sides of the rostrum at its hind part. In the last stage there was a fine bridge of cells running across behind the pituitary body; this is now a small cartilaginous “post-clinoid” bar. The opisthotic and epiotic form now a scarcely divided tract of bone, all the other centres are _ developing, and a pair of additional bones have appeared in the funnel-shaped fore-end of the chondrocranium ; these are the ‘“‘ lateral ethmoids.” The bony matter of the basi-occipital has now retired to: the hinder third of the notochord, which has much shrunken. There are now two centres (as in Amia calva) in the articular region of the mandible; the quadrate and metapterygoid centres are much larger; the hyo-mandibular and symplectic are together only half 112 Dr. F. M. Balfour and Mr. W. N. Parker. —_[ Dec. 8, the size of the mandibular suspensorium; the basi-hyal is very large, is composed of two parallel pieces, and is very Myainoid. Brief and imperfect as this ‘“‘ Abstract”’ is, I trust it is sufficient to show the extremely interesting and suggestive nature of this type ; any how, no clear understanding of the morphology of this type of skull ean be had unless it be seen in the light derived from that of the Elasmobranchs, the Sturgeon, and the Anurous larva on one hand, and that of Amia calva and the Teleostei on the other. III. “On the Structure and Development of Lepidosteus.” By F, M. Barour, LL.D., F.R.S., and W. N. PARKER. Re- ceived November 24, 1881. (Abstract. ) The authors commence this paper by thanking Professor Alexander Agassiz for the material, both embryological and adult, on which these researches were made. The first section is devoted to the general development. In this section an account is given of the structure of the ripe ovum, of the segmentation, of the history of the germinal layers, of the first development of the principal organs, and of the external features of the embryo during embryonic and larval life. The more important points established in this section, are— (1.) The ovum when laid is invested by a double covering formed of (a) a thick inner membrane, the outer zone of which is radially striated, and (d) an outer layer made up of highly refractive pyriform bodies which are probably metamorphosed follicular epithelial cells. (2.) The segmentation is complete, though very unequal; the lower pole being very slightly divided mto segments, and its constituent parts subsequently fusing together to form an unsegmented mass of yolk, ike the yolk-mass of Teleostei. (3.) The epiblast is divided into an epidermic and a nervous stratum, as in Teleostei. (4.) The walls of the brain, of the spinal cord, and of the optic vesicles are formed from a solid medullary keel, like that found in Teleostei. (5.) The lens, the auditory vesicle, and the olfactory pit, are wholly developed from the nervous layer of the epidermis. (6.) The segmental or archinephric duct is developed, as in Teleostei, from a hollow ridge of the somatic mesoblast, which becomes constricted off, except in front; thus forming a duct with an anterior pore leading into the body cavity. 1881.] On the Structure and Development of Lepidosteus. 113 The section on the general development is followed by a series of sections on the adult anatomy and development of various organs. The Brain. The authors give a fuller description of the adult brain than pre- vious anatomists. The new features in this description are (1) that the parts identified by previous anatomists as the olfactory lobes, are really parts of the cerebral hemispheres; the true olfactory lobes being small prominences at the base of the olfactory nerves; (2) that there is attached to the roof of the thalamencephalon a peculiar vesicle, which has not hitherto been noticed, but which is similar to the vesicle found by Wiedersheim on the roof of the thalamencephalon of Protopterus. They further show that the cerebrum is divided into a posterior portion, with an unpaired ventricle, and an anterior portion in which the ventricle is paired. ‘They consider the presence of a portion of the cerebrum with an unpaired ventricle, to be an indication that this part of the brain retains characters which are only found in the embryonic brain of other groups. They point to the presence of lobi inferiores on the infundibulum, of tori semicirculares in the mid- brain, and of a large cerebellum as indications of an affinity between the brain of Lepidosteus and that of Teleostei. In the embryological section full details are given as to the development of the thalamen- cephalon, the pineal gland, the cerebrum, and the olfactory lobes. At the end of the section the characters and affinities of the Ganoid brain are dealt with at some length; and the authors attempt to show that brains of Ganoids are distinguished (1) by the large size of the thalamencephalon, and (2) by the cerebrum being divided into an unpaired portion behind and a paired portion in front. - Organs of Special Sense. Olfactory Sacs.——An account is given of the development of the olfactory sacs, im which these sacs are shown to originate as invagina- tions of the nervous layer of the epiblast ; the communication between the sacs and the exterior being effected by the rupture or absorption of the superficial epidermic layer of the epiblast. The double opening of these sacs in the adult is described as arising from the division of the primitive single opening. ‘The olfactory nerve arises as an out- growth of the brain prior to the first differentiation of the olfactory bulb as a special lobe of the brain. Hye.—In the adult eye a vascular membrane is described bounding the retinal aspect of the vitreous humour. ‘This membrane is supplied by an artery piercing the retina close to the optic nerve, and the veins from it fall into a circular vessel placed at the insertion of the iris. The membrane itself is composed of a hyaline ground substance with numerous nuclei. 114 Dy. F. M. Balfour and Mr. W. N. Parker. [Dee. 8, In the developmental section devoted to the eye the main subject dealt with is the nature of the mesoblastic structures entering the cavity of the optic cup, through the choroid slit. It is shown that a large non-vascular mesoblastic process first enters the optic cup, and that together with the folded edge of the choroid sht it forms a rudi- mentary and provisional processus falciformis. Ata later period an artery, bound up in the same sheath as the optic nerve, enters the optic cup, and the vascular membrane found in the adult then becomes developed. The Suctorial Disk. The structure of a peculiar larval suctorial organ, placed at the end of the snout, is described, and the organ is shown to be formed of papillae composed of elongated epidermic cells, which are probably glandular (modified mucous cells), and pour out a viscid secretion. Muscular Systenv. The lateral muscles of Lepidosteus are shown to differ from those of other fishes, except the Cyclostomata, in not being divided into a dorso-lateral and ventro-lateral group, on each side of the body. Vertebral Column and Ribs. This section of the paper commences with a description of the ver- tebral column and ribs of the adult. In this part special attention is called to a series of cartilaginous elements, placed immediately below the hgamentum longitudinale superius,which appear to have escaped the notice of the anatomists who have previously worked at Lepidosteus. These elements are shown to be intervertebrally situated. With reference to the ribs the authors point out that for the greater part of their length they course along the bases of the intermuscular septa, immediately external to the peritoneal membrane, but that their free extremities bend outwards and penetrate between the muscles along the intermuscular septa till they nearly reach the skin. In the embryological part of this section a detailed account is given of the development of the vertebral column, of which the following is a summary :— There is early formed round the notochord a mesoblastic investment which is produced into two dorsal and two ventral ridges, the former uniting above the spinal cord. Around the cuticular sheath of the notochord, an elastic membrane, the membrana elastica externa, is next developed. The neural ridges become enlarged at each inter- muscular septum, and these enlargements soon become converted into cartilage, thus forming a series of neural processes, riding on the membrana elastica externa, and extending about two-thirds of the 1881.] On the Structure and Development of Lepidosteus. 115 way up the sides of the spinal cord. Hzmal processes arise simul- taneously with and in the same manner as the neural: they are small in the trunk, but at the front end of the anal fin they suddenly enlarge and extend ventralwards. Behind this point each succeeding pair of hemal processes becomes larger than the one in front, each process finally meeting its fellow below the caudal vein, thus forming a completely closed hemal arch. These arches are, moreover, pro- duced into long spines supporting the fin-rays of the caudal fin, which thus differs from the other unpaired fins in being supported by parts of the vertebral column, and not by separately formed skeletal elements. In the next stage which the authors have had the opportunity of study- ing (a larva of 55 centims.), a series of well-marked vertebral constric- tions are to be seen in the notochord. The sbeath is now much thicker in the vertebral than in the intervertebral regions: this being due to a special differentiation of a superficial part of the sheath, which appears more granular than the remainder, and forms a cylinder in each vertebral region. Between it and the gelatinous tissue of the notochord there remains a thin unmodified portion of the sheath, which is continuous with the intervertebral parts of the sheath. The neural and hemal arches which are of course placed in the vertebral regions are now continuous with a cartilaginous tube em- bracing the intervertebral regions of the notochord, and continuous from one vertebra to the next. A delicate layer of bone, developed in the perichondium, invests the cartilaginous neural arches, and this bone grows upwards so as to unite above with the osseous investment of separately developed bars of cartilage, which are directed obliquely ’ backwards. These bars, or dorsal processes, may be reckoned as parts of the neural arches. Between the dorsal processes of the two sides are placed median rods of cartilage, which are developed separately from the true neural arches, and which constitute the median spinous elements of the adult. Immediately below these rods is placed the ligamentum longitudinale superius. There is now the commencement, not only in the tail, but also in the trunk, of a separation between the dorsal and ventral parts of the hemal arches where the latter pass ventralwards, on each side of the body cavity, along the lines of inser- tion of the intermuscular septa. They are obviously the ribs of the adult, and there is no break of continuity of structure between the — heemal arches of the tail and the ribs. Inthe anterior part of the trunk, the ribs pass outwards along the intermuscular septa till they reach the epidermis. ‘Thus the ribs are originally continuous with the heemal processes. Behind the region of the ventral caudal fin the two hzemal processes merge into one, which is not perforated by a canal. Hach of the intervertebral rings of cartilage becomes eventually divided into two parts, which are converted into the adjacent faces 116 Dr. F. M. Balfour and Mr..W. N: Parker, Deen) of contiguous vertebre, the curved line where this will be effected being plainly marked out at a very early stage. As these rings are formed originally by the spreading of the cartilage from the primitive neural and hemal processes, the intervertebral cartilages are clearly derived from the neural and hemal arches. The intervertebral carti- lages are thicker in the middle line than at their two ends. In the latest stage examined (11 centims. long) the vertebral con- strictions of the notochord are rendered much less conspicuous by the intervertebral cartilages giving rise to marked intervertebral con- strictions. In the intervertebral regions the membrana elastica externa has become aborted at the posterior border of each vertebra, and the remaining part is considerably puckered transversely. The inner sheath of the notochord is puckered longitudinally in the inter- vertebral regions. The granular external layer of the sheath in the vertebral regions is less thick than in the last stage, and exhibits a faint radial striation. Two closely approximated cartilaginous elements now form a key- stone to each neural arch above ; these are directly differentiated from the hgamentum longitudinale superius, into which they merge above. An osseous plate is formed on the outer side of each of these carti- lages. These plates are continuous with the lateral osseous bars of the neural arches, and give rise to the osseous part of the roof of the spinal canal of the adult. Thus the greater part of the neural arches is formed by membrane bone. The hemal arches are invested by a thick layer of bone, and there is also a continuous osseous investment round the vertebral portions of the notochord. The intervertebral cartilages become pene- trated by branched processes of bone. The embryological part of this section is followed by a comparative part treated under three headings. In the first of these the vertebral column of Lepidosteus is compared with that of other forms ; and it is pointed out that there are grave difficulties in the way of comparing the vertebre of Lepidosteus with those of the Urodela, in the fact that in Lepidosteus the intervertebral cartilages originate from the bases of the arches, while in the Urodela they are stated by Gdotte to be thickenings of a special cartilaginous investment of the noto- chord, which would seem to be homologous with that cartilaginous sheath which is placed in Elasmobranchii and Dipnoi within the membrana elastica externa. On the other hand, the development of the vertebree of Lepidosteus is shown to resemble in most features that of Teleostei, from which it mainly differs in the presence of interver- tebral cartilaginous rings. In the second section, devoted to the homologies of the ribs of Pisces, the conclusions arrived at are summed up as follows :— The results of the authors’ researches appear to leave two alterna- 1881.] On the Structure and Development of Lepidosteus. 117 tives as to the ribs of fishes. One of these, which may be called Gotte’s view, may be thus stated:—The hemal arches are homolo- gous throughout the Pisces; in Teleostei, Ganoidei, and Dipnoi the ribs, placed on the inner face of the body wall, are serially homologous with the ventral parts of the hemal arches of the tail; in Hlasmo- branchii, on the other hand, the ribs are neither serially homologous with the hemal arches of the tail, nor homologous with the ribs of Teleostei and Ganoidei, but are outgrowths of the hemal processes into the space between the dorso-lateral and ventro-lateral muscles, and. outgrowths which may perhaps have their homologies in Teleostei and Ganoids in certain accessory processes of the vertebre. The other view, which the authors are inclined to adopt, is as follows:—The Teleostei, Ganoidei, Dipnoi, and Hlasmobranchi are provided with homologous hemal arches, which are formed by the coalescence below the caudal vein of simple prolongations of the primitive hemal processes of the embryo. The canal enclosed by the hzemal arches can be demonstrated embryologically to be the aborted body cavity. In the region of the trunk the hzemal processes and their prolonga- tions behave somewhat differently in the different types. In Ganoids and Dipnoi, in which the most primitive arrangement is probably retained, the ribs are attached to the hemal processes, and are placed immediately without the peritoneal membrane, at the insertion of the intermuscular septa. These ribs are in many instances (Lepidosteus, Acipenser), and very probably in all, developed continuously with the hzemal processes, and become subsequently segmented from them. They are serially homologous with the ventral parts of the hemal arches of the tail, which, like them, are in many instances (Ceratodus, Lepidosteus, Polypterus, and to some extent in Amia) segmented off from the basal parts of the hemal arches. In Teleostei the ribs have the same position and relations as those in Ganoids and Dipnoi, but their serial homology with the ventral parts of the hemal processes of the tail is often (e.g., the Salmon) obscured by the anterior hemal arches (/.e., those in the posterior part of the trunk) being completed, not by the ribs, but by independent outgrowths of the basal parts of the hemal processes. In Hlasmobranchii a still further divergence from the primitive arrangement is present. The ribs appear to have passed outwards, along the intermuscular septa, into the muscles; and are placed between the dorso-lateral and ventro-lateral muscles (a change of position of the ribs of the same nature is observable in Lepidosteus). This change of position, combined probably with the secondary formation of a certain number of anterior hemal arches, similar to those in the Salmon, renders their serial homology with the ventral parts of the hemal pro- cesses of the tail far less clear than in other types; and further proof 118 On the Structure and Development of Lepidosteus. [Dec. 8, is required before such homology can be considered as definitely established. Under the third heading the skeletal elements supporting the fin- rays of the ventral lobe of the caudal fin of various types of fishes are compared and the following conclusions are arrived at. (1.) The ventral lobe of the tail-fin of Pisces differs from the other unpaired fins in the fact that its fin-rays are directly supported by Spinous processes of certain of the hemal arches, instead of by in- dently developed interspinous bones. (2.) The presence or absence in the tail-fin of fin-rays, supported by heemal arches, may be used in deciding whether apparently diphycercal tail-fins are aborted or primitive. Urogenital Organs. With reference to the character of the adult urogenital organs, the authors show that for the female the descriptions of Miller and Hyrtl are substantially accurate, but that Hyrtl’s description of the genera- tive ducts of the male is wholly incorrect. They find that in the male the semen is transported from the testes by means of a series (40—50) of vasa efferentia, supported by the mesorchium. In the neighbourhood of the kidney these vasa unite into a longitudinal canal, from which transverse trunks are given off, which become continuous with the uriniferous tubuli. The semen is thus transported through the kidney into the kidney-duct (segmental duct), and so to the exterior. No trace of a duct homologous with the oviduct of the female was found in the male. With reference to the development of the excretory system, the authors have established the following points :— (1.) That the segmental (archinephric) duct is developed as in Teleostei. (2.) That a pronephros, resembling in the main that of Teleostei, is developed from the anterior end of the segmental duct. But they find that the pronephric chambers, each containing a glomerulus, into which the coiled pronephric tubes open, are not, as in Teleostei, completely shut off from the body cavity, but remain in communica- tion with it by two richly ciliated canals, one on each side of the body. (3.) The pronephros eventually undergoes atrophy. (4.) Some of the mesonephric tubes have peritoneal funnels in the larva. (5.) The ovarian sac continuous with the oviduct, is established by a fold of the peritoneal membrane, near the attachment of the mesovarium, uniting with the free edge of the ovarian ridge to form a canal, the inner wall of which is constituted by the ovarian ridge itself. 1881.] Ona New Mineral found in the Island of Cyprus. 119 (6.) The posterior part of the oviduct is not formed until the ovarian sac has become developed, and had not been developed in the oldest larva (11 centims.) the authors have succeeded in obtain- ing. The Alimentary Canal and its Appendages. In this section the authors give a detailed account of the topo- graphical anatomy of the alimentary tract in the adult. They have detected a small pancreas close to the bile-duct, and call special atten- | tion to a ventral mesentery passing from the posterior straight section of the intestine to the ventral wall of the body. In the embryological part of the section a detailed account is given of the development (1) of the pancreas, which is described as arising as a dorsal diverticulum of the duodenum on a level with the opening of the bile-duct; (2) of the yolk sac and vitelline duct; (38) of the spiral valve, which first appears as a hollow fold in the wall of the intestine, taking a slightly spiral course, and eventually becoming converted into a simple spiral ridge. The so-called hyoid gill, which the authors expected to find well developed in the larva, is shown not to be found even in the oldest larva the head of which was examined (26 millims.) The last section of the paper is devoted to the consideration of the systematic position of Lepidosteus. The Teleostean atiinities of Lepidosteus are brought into prominence, but it is shown that Lepidosteus is nevertheless a true Ganoid. The arguments used in this portion of the paper do not admit of being summarised. IV. “On a New Mineral found in the Island of Cyprus.” By PauLus F. Retnscu (Erlangen). Communicated by Pro- fessor STOKES, Sec. R.S. Received November 3, 1881, In the western part of the Island of Cyprus I detected, during my journey in June this year, a peculiar mineral, very remarkable not only from its chemical composition but also from the large percentage of extremely well-preserved siliceous shells of microscopic Radiolaria. The locality in this not much known part of Cyprus,* is situated between the village Chynussa and the mountains running in a north- * In the fine map of Kiepert (Berlin, 1878) this part of the island, in which the locality lies, is marked as “ wooded hill country, unexplored.’ In all the reports of travellers through Cyprus before and after the British occupation I find no notice of this tract, which must have attracted the attention of passing travellers, VOL. XXXIII. K 120) Ona New Mineral found in the Island of Cyprus. [Dec. 8, western direction, 38 miles N.W.W. in a straight line from the city of Limassol, 4 miles from the nearest point of the shores of Chrysohu Bay. ‘The mineral is found there in enormous quantities, it covers the sides of the top of a hill about 150 meters over the lowest part of the valley beneath. One side of the hill is covered with the pure mineral, partly in a crumbled state, partly as solid rock. On some places are found compact prominent rocks of the pure mineral from | to 2 meters height. The locality is destitute of any vegetation. The mineral is soft and chalk-like ; in a compact state it has a yellowish colour, in a powdered state an intense sulphur-like colour. The principal part of the mineral is composed of pure basic sulphate of oxide of iron, making 73 per cent. The striking yellow coloration of the slope attracted my attention, and I thought at first sight that I had before me a large layer of a pure sort of common yellow ochre. In ravines intersecting the slope and running down to the valley, especially on the lower parts, I observed the slopes covered all over with whitish and yellowish crusts of salt from 1 to 2 inches thick. These crusts sometimes cover the soil in the ground of the valley and excavations in the slope with whitish efflorescences, 30 to 50 meters below the yellow deposit. The substance must be partly soluble, it has a peculiar taste, giving the taste of sulphate of protoxide. On all those spots which are covered with the crusts of this salt there grows no vegetation of herbs, only shrubs cover the soil. During the dry season, lasting in this part of the island from June to August, the amount of salt, crystallizing and_ developed from the surface of the slopes, must constantly be in- creasing. The upper parts of the soil more and more drying up are filled up in the dry season with the efflorescence of salt, which is pre- viously in a dissolved state below the surface of the soil. This efflorescent salt in the lower parts of the ravines proves to be derived from the higher parts of the yellow deposit itself. Through the influence of the rain water in the wet season (October to December) quantities of the mineral being dissolved and carried down, quantities of the solution are sucked in from the soil; later in the dry season the salt makes efflorescences on the surface if the soil is drying up. The process of efflorescence of salt in the dry season and carrying away in the wet season is repeated from year to year. The salt seems to me to be a neutral combination, and is in small amount soluble in water. The mineral contains 1'7 per cent. hygroscopic water, and in the substance soluble in hydrochloric acid a very small amount of sul- phate of alumina. The hardness is nearly 2, equal gypsum, specific gravity 1:7. Heated to redness the mineral* turns from yellow to dark-brown * T assign to this mineral the name of the island, and to the many names of 1881.] On certain points in the Anatomy of Chiton. 121 and at last to red-brown, the colour of oxide; it loses in average 8 to 9 per cent. sulphuric acid with combined water. When dissolved in boiling hydrochloric acid a snow-white residuum is obtained, which, under the microscope, proves to be composed of extremely well-pre- served shells of microscopic Radiolaria, belonging to different genera. The size of those mostly regular globular bodies ranges between 0045 millim. and 071185 milim. The quantity of this residuum amounts in a mean of three trials to 25 per cent. The quantity of soluble substance is therefore 73 per cent., if we take away 2 per cent. hygroscopic water. This soluble substance is pure sulphate of oxide of iron with a very small amount of sulphate of alumina. The quantity of the sulphuric acid in the mineral was directly determined by precipitation of the hydrochloric solution of the mineral with chloride of barium. 2,000 mgrms. of the mineral gave 1,250 mgrms. sulphate of baryta, corresponding to 431 mgrms. sulphuric acid. The amount of this acid in the mineral is therefore 215 per cent. The quantity of the oxide with a small amount of alumina is 51°5 per cent., corresponding to 36 per cent. metallic iron. No traces of copper or any other metal have been found in the mineral; a trace of arsenic, however, is observed, as is shown by means of the copper-arsenic test, by boiling the hydrochloric solution with a clean copper slip, which becomes coated with a thin deposit of metallic arsenic. Cyprusit is composed as follows :— Oxide of iron, with a very small amount of alumina 51°5 SRPMPMTIICRACI Ose ore cic eee aig ws ai eu ge wa 4b ee ane 21°5 Misolmolersiliceous substance -............0---+4+: 25 PIRPAHOSCOPIC WAUCK- . 2. ec ee. ok at ee ale ee ec ne tees 2 100-0 VY. “On certain points in the Anatomy of Chiton.” By Apam NSEDGWICK, M.A., Fellow of Trinity College, Cambridge. Communicated by F. Marrnanp Baurour, F.R.S. Received November 5, 1881. An account of the structure of the kidney of Chiton has long been a want in morphology. Middendorff,* in 1848, described a branched. gland lying ventrally on each side of the body cavity which he identi- fied as kidney; but he records no observation on the structure of the objects belonging to natural history derived from Cyprus I add a new one; the mineral would bear the name “ Cyprusit.” * “ Mémoires de l’Acad. de St. Pétersbourg,”’ 6th ser., vol. vi. K 2 122 Mr. A. Sedgwick. Weers gland, and expressly states that he was not able to make out its opening or relation to other organs. Schiff,* ten years later, was unable to find this gland in Chiton piceus, and throws doubt on Mid- dendorff’s interpretation of its function. Von Jehringy has comparatively recently recorded some observations on the kidney of Chiton, and starts from the position that no kidney is known in Chiton, Middendorff’s view as to the nature of the branched gland having been sufficiently refuted by Schiff’s later observations. Von Jehring states that in the species of Chiton observed by him, the kidney consists of a branched gland lying ventral to the rectum in the hinder part of the body cavity, and that it opens by a single median pore ventral to the anus. He further figures this opening. While staying at Herm this summer I found a fair number of a good-sized species of Chiton—Chiton discrepans ; and the results which I have obtained from the study of the anatomy of this form, especially those which concern the kidney, seem to me sufficiently important for immediate publication. In the first place, 1 may mention that I have seen nothing in any of my dissections or sections which in the least supports von Jehring’s statements as to the existence of a median renal duct and opening; and that my observations are entirely opposed to the conclusion arrived at by this investigator as to the unpaired nature of the kidney of Chiton. On the contrary, Middendorff’s observations, so far as they went, were perfectly correct. The paired lateral branched gland described by the latter observer is part of the kidney. The kidney of Chiton is a paired gland with paired openings into the pallial groove and into the pericardium, and is constructed on the type always found in molluscan renal organs (fig. 1). It opens in the species I have chiefly examined (Chiton discrepans) into the pallial groove (fig. 1, 7.0.) internal to, but on a level with the last gill (16). The duct runs from the opening round the outside border of the - pallial nerve (fig. 2, 7.0.), and then passes inwards to open into a bladder-like structure placed in the body cavity (fig. 1, D, and fig. 2, D). This bladder-like structure les close to the body wall immediately beneath the pericardium (fig. 2, y.c.), and it does not seem to extend backwards beyond the last gill. On a closer examination by means of sections, it is seen to be beset by a number of branched glandular ceca, lying in the higder part of the body cavity (fig. 2, k.t.), which open into it, and into a backward prolongation from it (fig. 1, h.4.). These branched glandular ceca on opening the body cavity are seen as a mass of tubes apparently interlacing with those of the opposite side, and lying ventral to the * Schiff, “ Zeit. f. Wiss. Zool.,” Bd. ix. + ‘Morphol. Jahrbuch,” Bd. iv. ow) 1881. ] On certain Points in the Anatomy of Chiton. 12 EG ele A diagrammatic representation of the kidney and generative ducts of Chiton dis- erepans, viewed from the ventral surface. The pallial groove is represented as enclosed. by the lines p.g.; and in it are seen the 16 gills (br.), the generative (g.o.) and renal (v.0.) orifices ; and the anus(a.) The branched nature of the kidney is shown in the anterior part of the figure on the right side; posteriorly these secreting tubules are omitted. On the left side of the figure the kidney duct alone is indicated. a., anus; br., branchie; D, dilated part of kidney duct opening to exterior: g. points to the junction of the generative duct with the generative gland; the generative gland is supposed to be torn away ; g.d., generative duct ; 4.%., posterior part of kidney duct; g.o., generative orifice; %.¢., secreting tubules of kidney ; k.d., duct of kidney running forward, bending round at T and running back, receiving glands as far back as O. From O it runs to the pericardial opening p.o., receiving no glands; p.g., pallial groove; 13, 14, 15, 16, last four branchie ; the ventricle and auricular openings are indicated by dotted lines. 124 Mr. A. Sedgwick. [Dec. 8, rectum on the floor of the body cavity (fig. 2, %.¢.). This portion of the kidney has been seen and described by von Jebring, but instead of constituting the whole of the kidney and opening to the exterior by a median pore, it is only the posterior part, and opens on each side into the bladder-like structure which opens to the exterior in the =I | Cul rs A diagrammatic representation of a transverse section through Chiton discrepans at the level of the renal orifices (7.0., fig. 1). Dorsally is the pericardial cavity with the heart, separated by the pericardial floor from the general body cavity (0.c.), containing the viscera. Ventrally is the posterior apparently median unpaired part of the kidney (4#.¢. and &.c.) seen by von Jehring. A little in front of this section, the kidney tubules take up a distinctly lateral position. D; p.9.; 6.7.3; &.t.3 7.0. as m fig. 1, A, auricle ; V, ventricle; 0.v., branchial vein; 6.a., branchial artery; p.c., peri- cardial cavity; U.n., lateral nerve (pallial) ; p.x., pedal nerve; F, foot; A.C., ali- mentary canal; g.g., generative gland; 0.c., body cavity; &.c. see &.t.; p.k.d., part of kidney duct which in fig. 1 is hidden from view by D. position described above. I have many series of sections through this hinder part of the kidney of Chiton, which prove most conclusively that these hinder ventrally placed tubules do open in the way I have stated. On examining the anterior end of the bladder-like structure it is found that it is continued forwards as a duct (fig. 1, &.d.), which receives, all along its course, the ducts of bunches of branching glandular ceca, lying at the side of the body cavity (fig. 1, &.t.). These branching glandular ceca constitute the gland described by Midden- dorff. Their structure precisely resembles that of the first described 1881. ] On certain Points in the Anatomy of Chiton. 125 posterior tubules, which open into the dilated part of the duct and its backward prolongation. The duct can be traced forward to about the level of the 4th shell-plate (fig. 1, T), at which point it turns sharply round and runs back parallel with the first part of its course. A con- siderable part of the gland lies in front of this turning point of the duct; the secretion of this part is poured into a branch given off from the main duct at the bend (fig. 1, T). The posteriorly directed part of the renal duct lies close to the dorsal edge of the part running forward, and, like the latter, receives the efferent ducts of bunches of glandular ceca (fig. 1). From the level of the 5th shell-plate (fig. 1, O) to its posterior termination (fig. 1, p.o.), about to be described, it receives no glandular ceca, but runs backwards as a simple duct distinguishable by its brown colour, which is due to a deposit of colouring matter in its walls. On reaching the level of the bladder-like dilatation of the kidney duct first described, it applies itself to the dorsal inner wall of that structure as far back as the level of the last gill. At this point, which marks the hind border and the external opening of the bladder, it rans outwards and then forwards (fig. 2, p.k.d.) in close contact with the dorsal side of the lateral nerve cord. It runs forward to about the level of the penultimate gill, where it suddenly stops and opens by a small pore into the pericardium (fig. 1, p.o.) beneath, 7.e., ventral to the anterior part of the auricle. Comparing the arrangement of the kidney of Chiton with that of Anodon, there is seen to be a close agreement. In both the kidney is paired and consists of a gland bent on itself, opening at the one extremity into the pallial cavity, and at the other into the pericardium. In both the kidney is unsegmented (a fact to be remembered when the nature of the shell and gills of Chiton is discussed). There is a further agreement between these two animals in the relation of the openings of the generative ducts to those of the renal ducts; in both the latter are placed close behind the former. With regard to the minute structure of the kidney of Chiton, I have no exact observations. It is necessary to study it in the fresh state. The inner borders of the cells liming the glandular caea are stated by von Jehring to be ciliated. The most internal part of the kidney duct, 7.e., that which receives no glandular ceca (fig. 1, O to p.k.d.), is, with the exception of a small portion adjoining the pericardial opening, lined by columnar cells con- taining a yellow colouring matter, which gives this portion of the duct a yellow colour, easily visible to the naked eye. This yellow colouring matter, which seems to be part of the excretion of the cells lining the ‘ duct, is absent in the part of the duct which runs forwards from the level of the hinder edge of the bladder to the pericardial opening (p.k.d. to p.o.). Here are found large columnar cells provided with long cilia, which line also the pericardial opening. 126 On certain Points in the Anatomy of Chiton. [Deec. 8, The cells of the glandular ceeca seem to have the structure usually seen in molluscan renal organs, and have been correctly described by von Jehring. To sum up, the kidney of Chiton consists of— (1.) A duct opening to the exterior in the pallial groove behind the generative opening, and internally into the pericardium. (2.) Glandular ceca opening into this duct. The duct may be described as consisting of three parts :— (1.) The part into which the glandular ceca of the kidney open. This part is open behind where it opens to the exterior (fig. 1, D). In front it bends round (fig. 1, T), and runs hackwards to about the level of the 5th shell-plate, where it changes its character, and is continuous with (2) a duct (fig. 1, O) containing brown colouring matter in the columnar cells lining it, and receiving no glandular ceca. This part extends back to the level of the last gill, where it turns out- wards, and becomes continuous with (3) a part running forward for a short distance close to the lateral nerve, and lined by large ciliated eolumnar cells. This part opens in front at the level of the penulti- mate gill into the pericardium (fig. 1, p.o.). I expected to find the communication between the two parts of the renal duct behind in the region of the bladder, and for some time I was puzzled at not finding it. On mentioning the arrangement of parts to Mr. Balfour, he suggested that the communication might possibly be found in front, reasoning from the analogy of the structure of the kidney in other Mollusca. On examining the anterior part of the gland more care- fully, I at once found that his suggestion was correct, the two parts of the gland communicating as I have described. I have no observations to add to those of previous observers, on the general arrangement of the nervous system. J may mention that the lateral and pedal nerves have a coating of ganglion cells, and a central core of fibres. The animals are dicecious. The generative gland is unpaired and dorsal. The generative ducts are paired, and are attached to the hinder border of the gland, and open in Chiton discrepans into the pallial groove between the 13th and 14th gill, in a line with the open- ing of the renal duct. The duct passes dorsal to the anterior end of the dilated part of the renal duct (fig. 1, g.d.); and then curls round the outer border of the lateral nerve-cord to its opening, presenting in this respect precisely the same relation as does the renal duct. The male duct has a short direct course to its opening (fig. 1); while the female duct is much coiled. Another species, Chiton cancellatus, which I have examined, presents essentially the same arrangement of its renal organ and generative ducts as that just described for Chiton discrepans. Dall* states that in some species of Chiton, the generative products. * “ Proceedings of the United States’ National Museum,”’ vol. i. 1881.] The Action of Cutting Tools. 127 escape into the body cavity and make their exit by several pores placed close together, and symmetrically, on each side in the pallial groove ; oviducts apparently being absent. I have not any specimens of the species he mentions as possessing this peculiarity (e.g., Chiton mar- moreus and ruber), so have not been able to test his observations by means of sections. I hope to be able to give afuller account of these and other points in the anatomy of Chiton at some future period, for the preparation of which it will be necessary to obtain some fresh specimens. VI. “The Action of Cutting Tools.” By A. MALLocK. Com- municated by Lord RayLEIcH, F.R.S. Received Novem- ber 4, 1881. The action of cutting tools has not often been treated from a theo- retical point of view; in fact I only know of two papers on the sub- ject, one by Professor Willis and the other by Mr. Babbage. Of these Professor Willis’s paper is purely geometrical, showing what angles the edges of tools may make with one another if the cutting angles are to be such as experience shows to answer best. Mr. Babbage, on the other hand, does not enter at all on the question of the shape of the tool, but by making certain assumptions as to the relation between the dimension of the shaving removed by a tool and the work required to remove it, he deduces some results showing how to remove a given amount of material most economically. His con- clusions cannot be considered correct, nor do they agree with experi- ence (see Note 1). Ido not attempt in the following paper to give any dynamical investigation of the action of tools, in fact it would be almost impossible to do so without a more extended knowledge of the laws which govern the strains in bodies subjected to large forces, but merely to classify the various actions which observation shows to be caused by the progress of the tool, and to quantify approximately the work expended in each. Yor this purpose, shavings from a great variety of substances were examined both in the course of their forma- tion (by a microscope attached to the toolholder) and after they were removed. Among the substances examined may be mentioned four or five samples of wrought iron, and as many of steel, cast iron, gun metal, brass, copper, lead, zinc, hard paraffin, soap, and clay. This last-mentioned substance was found ‘extremely useful in examining the formation of the shavings, for by altering the amount of water it contamed its behaviour under the tool could be made to 128 Mr. A. Mallock. [Deexs: resemble almost any of the others, and at the same time the forces required to take large cuts were not greater than could be conveniently applied by hand. Sections were made of many of the metallic shavings, and the polished surfaces of these when washed with dilute nitric acid showed their internal structure very well. Figs. 1 to 8 show some of these sections enlarged. RiGee : Shaving of wrought iron (armour plate). Actual thickness °25 inch. Shaving of cast iron. Actual thicknes °1 inch. 130 Mr. A. Mallock. Fic. 6. Fig. 7. sy] a i (6 \\ h \ ) \ \V4 epetonl A (a.) Borings, steel. Actual thickness ‘005 inch. (d.) # brass. os & ‘OL bP) Shaving of copper (lubricated with soap and water). | Dec. 1881.] The Action of Cutting Tools. 131 Tt will be seen that there is little difference in any of these, though the materials are of all degrees of hardness, and vary in thickness from three-eighths of an inch, the thickest iron shaving examined, to ‘008. Indeed the action at the edge of the tool seems identical in all cases, such differences as there are being due to the action of the face of the tool on the shaving, while the latter is being pushed out of the way ; and this action depends on some of the physical constants of the substance operated on, chiefly its coefficients of friction on the metal of the too! and on itself, but in part also on its ductility, and in some cases, as in lead, on the property which freshly formed surfaces have of reuniting under pressure. The tools do not act, properly speaking, by cutting but by shearing, and the shaving removed by them may be accurately described as a metallic slate. This remark does not apply to acute-edged tools, such as razors and penknives. The difference between cutting and shearing may be defined thus : Conceive the substance to be cut to be divided into an infinite number of cubic elements by parallel planes at right angles to one another ; if in a portion of this removed by a tool the elements remain cubes, the removal has been effected by pure cutting. If, however, they are only distorted but are all unaltered in volume, the removal has been effected by pure shearing; if they are both deformed and altered in volume, both cutting and shearing have been called into play. Fie. 9. Let ABCD be a section of the substance under the action of the tool, GEF the tool, H the shaving, CD the undisturbed surface of the substance, and AB the direction of the cut. 132 Mr. A. Mallock. | Dee. 8, The advance of the tool violently distorts the material in its neigh- bourhood, and presently along the line ec the distortion becomes too great for the substance to preserve its continuity (Note 2), the lamina ECec then begins to slide on ec, and its base He to move up the face of the tool, while the point of the tool is repeating the distortion and separation on fresh material ahead. This in all the cases I have examined is the manner in which all tools, except those with very acute angles, act. The curvature of shavings appears to be due to the crushing of the base of the laminz while passing over the face of the tool, thus making them thicker at that end than at the outer surface. The effect of the friction between the lamine and the tool has the opposite tendency of thinning out the ends of the lamine and preventing the curvature, so that when from want of lubrication or the nature of the material the friction becomes excessive, the shavings are nearly straight. The shaving is generally shorter than the path of the tool, which shows that BED is less than 45°. I will now attempt to take account of the forces which are brought into play by the action of the tool. These are due to (1) elastic distortion, (2) elastic bending, (3) per- manent distortion, (4) permanent bending, (5) internal friction, 7.e., the friction of the lamine sliding over one another, (6) the friction of the material on the tool, and (7) if the tool is not considered as being perfectly sharp, the radius of curvature of. the edge will appear in a term giving the limit to the rate of distortion in its neighbourhood. If the tool is perfectly sharp the rate of distortion at the edge is in- finite, and the material at the edge can offer no resistance to its pro- gress unless capable of infinite distortion without rupture. This is easily seen to be the case by the following considerations :— Fria. 10. Let ABCD (fig. 10) be the section of a parallelopiped of any mate- rial, and let it be distorted as shown by the dotted lines until rupture takes place. The work expended in bringing it to its distorted state depends on Bi, #.e., the distance AD must be moved before the limit of distortion is reached, and this is simply proportional to BD, the 1881. | ~The Action of Cutting Tools. 133 thickness of the parallelopiped; hence when BD is nothing the work is also nothing. The rate of distortion, 7.e., the distortion produced by a definite motion of AD, is inversely as BD, and is therefore in- finite when BD=0. Thus, when the rate of distortion is infinite and the limit of distor- tion is finite, no work is required to effect the rupture. In the case of the tool it is, of course, only actually at the edge that the rate of distortion is infinite; but if it were possible to apply suit- able forces simultaneously at every point of a solid through which a surface of separation was desired to pass, that separation could be effected with no expenditure of work whatever. The resistance due to elastic and permanent distortion is a 3 being the angle DEB (fig.11), Q the integral of all the reaction due to distortion along the line EC at the moment sliding begins. The work done in internal friction is HC x distance through which the lamina slides per unit travel of tool X by the pressure under which the sliding takes place x by the coefficient of friction of the material on itself. Pires Let <=BC, the thickness of the cut, t’ =thickness of shaving, “= coefficient of friction of the material on itself, p,=coefficient of friction of material on the tool, 6—DHB; o~=FEA, viz., the angle which the face of the tool makes with - AB, then eNO?) st en Mek Mange sin 0 Ei ail (2). sin 0 134 Mr. A. Mallock. (Dee: The sliding along ED per unit advance of tool is— cos0+cot(@+0)sin@ . . ., .. . (@). The pressure under which the sliding takes place is to the normal pressure on the face of the tool as cos (0+) +a, sin (046)... eo Thus the work expended in internal friction is proportional to pz {(cos 9+ sin 0 cot (p+0)) (cos (+0) +, sin (6+))} . (5). The work done in friction against the face of the tool is for the same travel proportional to in 0 ee ae 6). A" sin (p+) Collecting these results, the total resistance will be made up as follows :— (1.) Bluntness=Ap where p=radius of edge and A=constant. (2.) Hlastic and permanent eter cos 9 . I eS (3.) Internal friction= 5 —{ (cos 0+ sin 0 cot d+ 6) (cos$+0+p, sin P+) }. Ne : tsin 0 4.) Frictio $:(00k, = 1h see (4.) Friction against too eaeice (5.) Hlastic bending = B??. Considering these terms in order :— The first ought always to be small if the tool is sharp. Q in the second term is proportional to ¢, and is probably a function also of @ and @, but as observation shows that @ is independent of ¢, that is to say, that for a given material any form of tool that can be employed causes sliding to begin in the same plane, it seems lkely that the reaction due to distortion should not vary much with ¢, and that for the present purpose @ may be regarded as ¢ x constant. The internal friction vanishes when cOsS@+O0——p,sng@+6 . . 2) Ui eee that is, when the resultant force through the face of the tool is parallel to HC. When this is the case, however, there is a large component tending to make the tool dig into the substance, so that the form indicated by A is not one which can be used in practice without certain precautions. 1881. | The Action of Cutting Tools. 135 The same objection applies to making the fourth term a minimum by putting ne men Onn et LOM RINE CRN Perhaps as good a value as any for @ is that which makes the resultant force through the face of the tool parallel to the direction of motion. This value is given by the equation COUD= rasa mis els tier CU) The values obtained for ¢ for this expression agree fairly with those in common use, or at least are quite compatible with them, considering the uncertainty of the values of », for high pressures. The elastic and permanent bending is small for such values of ¢ as can be used in tools for metals, the transyerse strength of the shaving (which is some hundred times less than that of a piece of the substance of the same dimensions in its natural state) not permitting it to transmit large bending forces. In true cutting tools, where ¢ is very small, nearly the whole force acting on the blade arises from friction under the pressure on the sides of the tool caused by the bending. It is evident, therefore, that as ¢ passes from large values to small, the importance of the term in ¢ will continually increase. All the sources of resistance above mentioned, except the first and last, which should be small, are proportional to the thickness of the shaving and, of course, also to its breadth. Thus to remove a given volume of material will require the same expenditure of work, whether it be effected by one thick cut or several thinner ones. In practice, however, the constant friction of the machinery em- ployed always make thick cuts the most economical. The construction of machines, and the character of work generally, confines within rather narrow limits the thickness of the cut which it is possible to take, for the force required must not be large enough to sensibly bend or distort the substance as a whole. It would be a great advantage if tools could be so held or shaped that their accidental vibrations should not be sustained but extinguished by the reactions which they call into play; but to make this possible the phase of the vibration of the tool must precede that of the reaction which it causes by some time less than half the period of the tool, or, in other words, the resistance experienced by the tool must increase with its velocity. Now friction between solids being rather greater at low than at high velocities, the sliding cf the shaving on the tool tends to keep up a vibration once started, and the same may be said of the forces due to the distortion of the substance, which are at a maximum Just before a fresh lamina (such ase... .c, fig. 9) begins to slide, and wOu, XXXII. L 136 Mr. A. Mallock. [Deensy then suddenly drop toa minimum. It is plain also that a tool with a tendency to dig will call into play forces of a like character. Vibrations are in some degree neutralised, and digging entirely avoided, by so shaping the shanks of tools that the centre about which they vibrate is in advance of the normal to the direction of motion through the cutting edge. Rie. 12. Let p be the distance of the centre of flexure (s) from the cutting edge (P), « the angle which the line joining the centre of flexure and edge makes with the normal, and éx the angular distance of the tool from its mean position, the thickness of the shaving removed is t+ pda tan «, and if 7 be the period of the vibration of the tool, éz is propor- tional to sin ¢7, or é#=« sin ¢7, say, « and ¢ being constants; and since the pressure exerted by the shaving on the tool is proportional to its thickness, px sin ct tan a also expresses the variable part of the reaction. The effect of this variable pressure is neither to sustain nor extinguish the vibration, but to increase in effect the rigidity of the tool by a quantity proportional to tan a. In tools designed for rough work « is usually small, but when the quality of the surface left by the tool is of more importance than the thickness of the shavings which it can remove, it may be largely mecreased with advantage. Hig. 13. Fig. 13 shows an excellent form of cutter-holder, designed by the late W. Fronde, F.R.S., in which @ is about 45°. Tools held by such a cutter-holder leave a very smooth surface on the substances 1881.] The Action of Cutting Tools. HT which they cut, and at the same time may have smaller values for @ given to them than when held in any other way with which I am acquainted. The general conclusion to which the foregoing remarks point are :— (1.) Work has to be expended in dividing substances merely because the necessary forces cannot be applied locally enough; the more local the application of the force, the less is the travel, and therefore the work required to effect the separation. (2.) All ordinary tools act by shearing the substance on which they operate in a plane inclined at an angle of less than 45° to the plane or surface swept out by the edge of the tool. (3.) To remove a given volume of material requires nearly the same amount of work, as far as the tool itself is concerned, whether it be removed in few cuts or many; but the constant friction of the machinery always makes the thicker cuts more economical in practice. (4.) Tools for heavy work should be so shaped that the resultant force on them may lie nearly in the direction of motion. In order that this may be the case, @ must be determined by equation (C). If a less value for @ than this be adopted, less work will be required to effect the same cut, but the tool will have a tendency to dig. (5.) In tools which are merely required to leave a good surface and not to take cuts of any appreciable depth, the angles are unimportant. One curious point connected with the subject of cutting tools is the manner in which their action is facilitated by lubricants. Lubricants seem to act by lessening the friction between the face of the tool and the shaving, and the difficulty is to see how the lubricant can get there, since the only apparent way is round the edge of the tool, and there it might be expected that the contact between the tool and the substance would be too close to admit of its passage. Somehow or other, how- ever, some of the lubricant does find its way between the shaving and the tool, and perhaps also into the substance of the shaving. Some metals, copper for instance, when unlubricated, actually refuse to slide over the face of the tool, and the metal is then driven before the tool in a growing lump, as stiff mud would be before a board pushed through it (fig. 6). The separation in these cases does not take place at the edge of the tool, but some distance beneath it. Note 1.—On Mr. Babbage’s Paper on the Principles of Tools for Turning and Planing Metal. Mr. Babbage, in the paper above referred to, assumes that the force required to remove a shaving of constant width may be expressed in terms of its thickness by the series A+ Bi+ Ci?+ &c., and this of course is perfectly true. But in his application he reduces this series to two terms only, viz., A and Ct; of these he says that A is the constant force ‘‘ necessary to tear along the whole line of section L 2 138 The Action of Cutting Tools. [Deere each atom from the opposite one to which it was attached.” C#? is of course dependent on the bending and material. As to the first of these terms, I have shown that it is =0 when the tool is sharp; and the second must be small, in the first place, because but little true bending occurs, and, secondly, because the resistance which a shaving can oppose to bending is, on account of its laminated structure, very feeble. Note 2.—Though the general line of shearing is in the direction e, ¢, it can hardly be doubted that separation first occurs across the lines of greatest tension. lire Wek Let f, g, h, k, be a small cube of substance contiguous to ec, and unstrained ; let f’, g’, h’, k’, be the same substance when strained and just about to shear. The lines of greatest tension are parallel to p, 9’, and rupture will take place in a direction at right angles to this. Ruptures of this kind will happen all along the line ec, and the saw-tooth-edge left will be rubbed down when the lamina begins to slide. | Paper ruptured by distortion. 1881.] J. Milne and T. Gray. On Seismic Ewperiments. 189 Rupture along the lines of greatest tension in shearing may be well illustrated by pasting a piece of paper over two flat boards, with straight parallel edges, about 3” apart; if now, preserving this dis- tance, the boards are forced to move past one another in the direction of their edges, folds appear in the paper parallel to the lines of greatest tension, and if the sliding be continued the paper tears at right angles to the direction of the folds (fig. 15). VII. On Seismic Experiments.” By Joun MILNE, F.G.S., and THomas GRAY, B.Se., F.R.S.H. Communicated by A. C. Ramsay, LL.D., Director-General of the Geological Survey and of the Museum of Economic Geology. Received November 5, 1881. (Abstract. ) This paper is an account of aseries of experiments made at the Akabane Engineering Works, Tokio, for the purpose of investigating some points connected with earthquake motion. The mode of experi- ment consisted in creating a disturbance at a point on the earth’s surface by allowing a heavy block of iron (1,710 lbs.) to fall from a height (35 feet), and observing the resulting motion produced in the earth at points variously situated relatively to the centre of disturbance. The centre of disturbance was situated near to one corner of a pond about 10 feet deep, and close to the foot of a small steep hill, the remaining ground being very nearly level, and composed of hardened mud, which extended to a depth of from 20 to 30 feet. The configu- ration of the ground here briefiy described is clearly shown by means of a map accompanying the complete paper. In the earlier experi- ments a number of similar vessels of mercury were placed at the different points, and the vibrations produced on the surface taken as a rough indication of the intensity of the disturbance at the point. This method of observation showed with considerable definiteness where the motion became insensible. These preliminary experiments showed that the disturbance could be distinctly propagated to a dis- tance of 650 feet (which was the greatest distance available); that the pond cut off the disturbance from points beyond its distant side if these points were sufficiently removed from the corner, but that the hill did not cut off the vibrations. In subsequent experiments more definite observations were made by using seismographic apparatus, and by this means the following conclusions were reached. A disturbance emanating from a centre as above described, pro- duced at least two distinct sets of vibrations. One of these sets has 140 Dr. G. Gore. On the [Dec. 8, the direction of motion in the line joining the centre of disturbance and the point of observation, while the other set has the direction of motion at right angles to that line. The first of these is denominated the direct wave, and the second the transverse wave. The direct wave has a greater amplitude and a slightly shorter period of motion at the source, but seems to die out more rapidly than the transverse wave. The amplitude of the direct vibrations seems never to have exceeded 0°5 millim. at 50 feet, and 0-1 millim. at 250 feet from the centre. The amplitude of vibration was very nearly inversely as the distance from the source. The direct wave was completely cut off by the pond and nearly, if not completely, by the hill, but the transverse wave extended along the distant side of the pond to a considerable distance, and was little affected by tke hill, When the motion of a point on the earth’s surface was registered by means of a seismograph, it was found to be such as would result from the composition of two harmonic motions of different period, and in different directions. One of the most important points attended to in these experiments was the determination of the velocity of propaga- tion for the different waves. The method finally adopted for this purpose was to mark by means of a telegraphic arrangement, simul- taneously, and at definite intervals, on two smoked glass plates, placed at different distances along the same line from the source, the same instant of time. These plates were moved by cleckwork, and were used for the reception of the seismograph record. ; It is evident that the time-marks on the plate give the means of comparing the times of arrival of the direct, or the transverse wave, according to circumstances at the two stations, and hence, knowing the time-interval between the marks on the plates, the velocity of propagation could readily be calculated. As the result of these observations the surprisingly low velocity of 438 feet per second for the direct, and 357 feet per second for the transverse wave, was obtained. The soft nature of the material through which the disturbance was propagated is given as the probable reason for this result. The results of similar experiments by Mr. Robert Mallet, at the Hellgate explosions, in New York Harbour, are referred to. At the conclusion of the paper an example of the records obtained in actual earthquakes is given and briefly described. VIII. On the Electrolytic Diffusion of Liquids.” By G. Gorz, LL.D., F.R.S. Received November 8, 1881. In a paper on the ‘‘ Influence of Voltaic Currents on the Diffusion of Liquids ”’ (‘‘ Proc. Roy. Soc.,” vol. 32, 1881), I described a number 1881. ] Electrolytic Diffusion of Liquids. 141 of phenomena resulting from the passage of an electric current verti- cally through the boundary surfaces of mutual contact of two electrolytes lying upon each other. As it was not possible by means of the apparatus employed in that research to definitely ascertain whether the mass of liquid expanded or moved as a whole in the line of the current, I devised the following arrangement for the purpose of more conclusively testing that question, and to obtain additional data to assist in explaining the phenomena previously observed. A is a glass vessel containing the heavier liquid, B is a glass tube about 15 centims. long and 2 centims. diameter, containing the lighter solution, and capable of being raised and lowered by means of the vack C and a pinion (not shown in the sketch), attached to a fixed upright support. The tube B is closed at the lower end by an india-rubber bung, in a hole in the centre of which is fixed the open glass meniscus tube D, about 16 millims. long, and having a bore of about 6 millims.; it is also closed at the top by a perforated bung, through which proceeds an open glass tube H, of somewhat smaller 142 On the Electrolytic Diffusion of Liquids. (Decree diameter than the meniscus tube, and about 15 centims. long. To the upper end of Hi is attached an india-rubber tube I, provided with a pinch-tap G. H and I are two sheet platinum electrodes, each about 7 centims. long, and 18 millims. wide, for connexion with a voltaic battery. ‘The connecting wire of H is hermetically sealed in a glass. tube, which fits air-tight into the bung. In using this apparatus, the vessel A is shifted from its place, and the heavier liquid poured into it. The tube B is then filled by means of suction at J with the lighter liquid up to a level in H, a little above the bung. The tube F is then closed by means of the pinch-tap G, the vessel A replaced, and B, &c., lowered by means of the rack and pinion until the pressure of liquid in A just balances that in B, the difference of level being approximately determined beforehand, by taking the specific gravities of the two liquids. A definite meniscus is then easily formed in the tube D, by opening the pinch-tap and raising B until a drop of liquid issues below, and then lowering it a minute distance. Itis particular that no air bubble exists in B, and in order to facilitate the escape of any, the interior of the upper bung is made of a funnel shape, and coated very smoothly with sealing wax. ; In an experiment I made with this apparatus, the heavier liquid was a solution of nitrate of mercury of specific gravity 1°30, and the lighter one a solution of cupric nitrate, specific gravity 1:22. With an upward current from 18 Grove’s elements in single series, a colour- less horizontal line soon appeared below the meniscus in D, advanced - downward, and underflowed the end of the meniscus tube. Neither the meniscus in the lower tube D, nor that in the upper one H, shifted in position during the passage of the current. These results were repeatedly verified with the meniscus at different distances, varying from one-sixteenth to one-eighth of an inch above the bottom of the: tube. Remarks.—These results show first, and most conclusively, that liquid diffused downwards continuously through the meniscus during the passage of the upward current; and second, that during the con- tinuance of the current, either no manifest expansion occurred in the bulk of the liquid in B, and that equal volumes of liquid diffused in two opposite directions through the lower meniscus; or, that any expansion of the bulk of liquid in tube B was compensated for by downward diffusion of an equal bulk of liquid. Another possibility is. that the united volumes of the metallic deposited copper, and of the acid element from which it had been separated by electrolysis, was greater than before such separation, and that this was compensated for by the volume of liquid diffused downwards through the meniscus. 188]. | On the Coefficients of Expansion, §c. 143 IX. “On the Coefficients of Contraction and Expansion by Heat of the Iodide of Silver, AglI, the Iodide of Copper, Cuyl,, and of Five Alloys of these Iodides.” By G. F. RODWELL, F.R.A.S., F.C.8., Science Master in Marlborough College. Communicated by Professor A. W. WILLIAMSON, For. Sec. R.S. Received November 11, 1881. (Abstract. ) The experiments described in this paper are a continuation of those published at intervals during the last five years in the ‘‘ Proceedings ”’ in connexion with the anomalous expansion by heat of certain iodides. Fresh and more accurate determinations of the coefficients of con- traction and expansion of iodide of silver are given. Certain physical and chemical properties of cuprous iodide are detailed, and determinations of its coefficient of expansion by heat. « Five alloys of iodide of silver with cuprous iodide were prepared, having the following composition and percentage of iodide of silver :— Composition. Percentage of iodide of silver. (Craig Ln Yaa | a i rat 38° 2233 Ciel Or a 55-3066 (Oitin La oula\’od La ree ear 649884 (Oita ec Dee eh eae 71°2225 Clie gO E eee 88-1304 The physical properties of these bodies are described, and their coefficients of contraction and expansion are determined, and the volumes between 0° C. and the melting point are deduced therefrom. A general discussion of the results is afterwards given, in which these alloys are compared with the five chlorobromiodides of silver previously described (‘‘ Proc. Roy. Soc.,” vol. 25, p. 303), and with the lead-silver iodide alloy, the properties of which were described in the last communication of the author on this subject (‘‘ Proc. Roy. Soc.,” vol. 32, p. 540). The following are some of the facts noticed in connexion with the alloys :— 1. The specific gravity varies but slightly, viz., from 5°7302 to: 5°6950, and is little above the mean specific eravity of the con- stituents. ? . 2. The melting points are in all cases much lower, for while the melting point of iodide of silver is 527° C., and of iodide of copper 144 On the Coefficients of Expansion, &c. (Dec. 6; 601° C., the highest melting point of any one of the alloys is 514° C., and the lowest “493° C. 3. Some of the alloys possess three points of similar density, aan some two, at different temperatures. They are resinous in fracture and transparent in thin layers. When pulverised they furnish brilliantly yellow powders, unaffected by light. 4. When heated in a current of carbonic anhydride they volatilise very slowly. Heated in dry oxygen iodine is freely evolved, and oxide of copper appears on the surface of the mass. When heated in dry hydrogen, hydriodic acid is produced, and the metal is reduced. 5. The coefficients of expansion of the alloys below the point at which contraction on heating commences, was found to decrease as the percentage of iodide of silver was augmented. Thus— Percentage of AglI. Coefficient of expansion. SO CLOG yal Saeco ee 00004998 is OO One Meet lt a as choot "00003750 G4 9894 Ue a ake see 00002307 E2220 0 a Pe eo ee ‘00001998 foo fel #310) ie iy Mice a a6 oe ‘00000636 The same fact was observed in the case of the chlorobromiodides of silver. A curve table shows results. 6. While the iodide of silver commences its considerable contrac- tion at 142° C., the five chlorobromiodides of silver, the percentage of iodide of silver in which varies from 26°1692 to 73°9285, and the lead-silver iodide alloy, the percentage of iodide of silver in which amounts to 33°794, all commence their contraction at 124° C., that is, 18° C. lower, although the coefficients of expansion of the associated bodies necessarily differ. Thus it would appear that 124° C. is the temperature at which iodide of silver commences its passage from the crystalline into the amorphous condition, when freed from the attrac- tion of its own molecules, provided no other attraction or influence supervenes ; while the attraction exerted when it exists unalloyed with any other substance, and when its molecules are hence much nearer to each other, raises the point of commencement of the change to 142° C. 7. The probable cause of this is discussed. 8. When the same result was looked for in the case of the copper- silver iodide alloys it was not found. Im fact, the presence of the iodide of copper, instead of promoting the assimilation of molecular motion, and lowering the point at which the change from the crystal- line into the plastic condition commences, was found to considerably raise it, although the coefficient of expansion of the iodide of copper is lower than that of either chloride or bromide of silver, or of the iodide of lead, which enter into the composition of the other alloys. 1881.] Vibrations of a Vortex Ring, &§c. 145 Percentage of iodide of silver in Temperature at which con- the copper-silver iodide alloys. traction on heat commences. SOO man Renn ea ais Soho cial a = « 284° C. SOL GOME Meet yo an seccet 233 GAO SAR Rey usted 50° 50-42 214 NZ 22 eee a) airs) 4) cscs. ai tv's 199 polord ie (0/8 Pe er Pree aera 153 Thus while 66°206 per cent. of iodide of lead lowered the point of change 18° C., the presence of 61°7767 per cent. of iodide of copper raised it 142° C. 9. The possible causes of these results are discussed. 10. The lead-silver iodide alloy is compared with the copper-silver iodide alloy, as to structure, properties, &c. 11. The results of the microscopic examinations of these alloys is given, and shown by drawings. 12. The special properties of each alloy are described. Hrratum.—* Proc. Roy. Soe.,” vol. 32, p. 550, 16 lines from bottom of page: for “more than twenty times,” read “ nearly four times.” X. “On the Vibrations of a Vortex Ring, and the Action of Two Vortex Rings upon each other.” By J. J. THomson, B.A., Fellow of Trimity College, Cambridge. Communi- cated by Lord RAYLEIGH, F.R.S. Received November 16, 1881. (Abstract. ) In the first part of the paper it is shown that if the circular axis of a vortex ring be displaced so as to be represented by the equations— p=a+ 4, cos nd, z=, cos nd. when p is the distance of a point on the circular axis from the straight axis, and z the distance of a point on the circular axis from its mean plane, then— an— A cos ( ee log 2a, Vne—1. b-- B), e 2a? (a — soeS) sin ( VT when w is the angular velocity of molecular rotation, e the radius of the cross section of the vortex core, and a the radius of the aper- te Le os 7 log nn Vne—1 i+B), e 2a? 146 On the Vibrations of a Vortex Ring, &e. | Dec. 8, ture. The cross section is supposed small compared with the aperture, so that e is small compared with a. Thus the time of vibration is— Q7| — log ees Vne—, 2a° e and the motion is stable for all such displacements. In the second part of the paper the action of two vortices, which move so as never to approach nearer than a large multiple of the diameter of either, upon each other, is considered, and the following results among others obtained :— If e be the angle between the direction of motion of the vortices, c the minimum distance between their centres, v the velocity of trans- lation of vortex (i), w that of vortex (11); « and § angles given by— W COS a=v COS £, a+ Pp=e. m and m' the strength of vortices (1) and (11) respectively, 2 and 5 their radii; i the relative velocity of the vortices, viz., V/ 72+ w2—2Qvw cose: : then, in the standard case when the vortices are moving in the same direction and (1) first passes through the points of intersection of their directions of motion, we have the following results :— The direction of motion of Iis deflected towards the direction of motion of II through an angle whose circular measure is— m’b?a cos « Sin 2B i:c3 The direction of motion of II is deflected in the same direction through an angle— ma*b cos B sin 2a aes ses The radius of vortex (i) is increased by— am b?a cos a(1+ cos 228) fon The radius of vortex (11) is diminished by— mab cos B(L + cos 2a) ke? The effects for all circumstances of motion, whether the vortices are moving in the same or opposite directions, may be summed up in the following rule :— 1881.] Letter by Dr. W. Roberts. 147 The vortex which first passes through the point of intersection of the direction of motion of the vortices is deflected towards the direc- tion of motion of the other, it increases in radius and energy, and its velocity of translation is diminished ; the other vortex is deflected in * the same direction, it diminishes in radius and energy, and its velocity of translation is increased. XI. Letter addressed to the Secretary R.S. by Dr. W. RoBERTS, F'.R.S. Recerved December 1, 1881. In deference to the request of Mr. W. R. Dunstan, I wish to correct an error of omission in my paper ‘‘On the Hstimation of the Amy- lolytic and Proteolytic Activity of Pancreatic Extracts,” printed in “Proc. Roy. Soc.,” vol. 32, p. 145. Mr. Dunstan points out to me that I had overlooked a paper by himself and Mr. A. F. Dimmock on the ‘ Estimation of Diastase,’’ published in the ‘“ Pharmaceutical Journal” for March 8th, 1879, wherein he described a process, in which (as in my method) the cessation of the iodine reaction is utilised for the purpose of gauging the activity of diastasic solutions on starch gelatine. I had not previously seen this paper, and am now glad to have the opportunity of referring to it those who are interested in diastasi- metry. 148 Dr. J. B. Sanderson. (Decmiae December 15, 1881. THE PRESIDENT (followed by THE FOREIGN SECRETARY)” in the Chair. The Right Hon. Sir William Vernon Harcourt, whose certificate had been suspended as required by the Statutes, was balloted for and elected a Fellow of the Society. The Presents received were laid on the table, and thanks ordered for them. The following letter addressed to the President of the Royal Society was read :— Institut de France, Paris, 5th of December, 1881. My pzar Mr. Presiprnr,—In the meeting of the Academy of to-day M. Dumas has read a letter from Professor Williamson, informing the Academy that the Copley Medal has been awarded to me. I know well and appreciate highly the value of that reward, and I beg you to offer to the Royal Society my sincere thanks. That illustrious body honoured me, seventeen years ago, by electing me as one of its foreign members, and now has been pleased to crown my far advanced scientific career. I beg leave to give to my Hnglish colleagues a proof of my respect- ful regard by presenting to them the first results of new researches on the synthesis of oxygenated bases. By the reaction of glycol-chlor- hydrine on collidine and on quinoline I have obtained new alkaloids, which present a close connexion with neurine. Very soon I intend to send over to Professor Williamson a paper on that subject. Iam, with the highest regards, Sincerely yours, Joy | WU) 10'Z, President of the Académie des Sciences. The following Papers were read :— I. “On the Electromotive Properties of the Leaf of Dionsa in the Excited and Unexcited States.” By J. BURDON SANDERSON, M.D., F.R.S., &c. Received October 27, 1881. (Abstract. ) The paper consists of five parts. Part I is occupied by the exami- nation of two experimental researches, relating to the subject, which 1881.] Llectromotive Properties of the Leaf of Dionea. 149 have been published in Germany since the date of the author’s first communication to the Royal Society in 1873,* namely, that of Pro- fessor Munk on Dioneza, and of Dr. Kunkel on electromotive action in the living organs of plants. According to Dr. Munk, the electric pro- -perties of the leaf may be explained on the theory that each cylindrical cell of its parenchyma is an electromotor, of which the middle is, in the unexcited state, negative to the ends, and that on excitation the electromotive forces of the cells of the upper layer undergo diminution, those of the lower layer an increase. He accounts for the diphasic character of the electrical disturbance which follows mechanical exci- tation by attributing it to the opposite electromotive reactions of the two layers of cells. According to this theory, the cells resemble in their properties the ‘‘ electromotive muscle-molecules” (“ Unier- suchungen,” vol. i, p. 682, 1848, of du Bois Reymond) differing from them in so far that their poles are positive instead of being negative to their equatorial zones. Professor Munk has constructed a schematic leaf in which the cells are represented by zinc cylinders with copper zones. A schema so made is said by him to have the electromotive properties of the unexcited leaf. Dr. Kunkel’s experiments have for their purpose to show that all the electromotive phenomena of plants may be explained as conse- quences of the movement of water in the organs at the surfaces of which they manifest themselves. Part II contains a description of the apparatus and methods used in the present investigation. In Part II] are given the experimental results relating to the electro- motive properties in the unexcited state, a subject of which the discussion was deferred in the paper communicated by the author (with Mr. Page) in 1876., The fundamental fact relating to the distribution of electrical tension on the surface of the leaf when in the unexcited state is found to be that (whatever may be the previous electrical relation between the two surfaces) the upper surface becomes after one or two excita- tions negative to the under, and remains so for some time. This difference of potential between the two surfaces the author calls the “‘ cross difference.” It is shown that, under the conditions stated, its occurrence is constant, and that the differences of potential which present themselves when other points of the surface of the leaf are compared, may be explained as derived from, or dependent on, this fundamental difference. Part IV relates to the immediate electrical results of excitation, 7.e., to the electrical phenomena of the excitatory process. In investigating these the author takes as the point of departure, an experiment which includes and serves to explain those obtained by other methods, and * “ Proceedings,” vol. 21, p. 495. + “‘ Proceedings,” vol. 25, p. 411. 150 —_ Hlectromotive Properties of the Leaf of Dionea. [Dec. 15, is therefore termed the ‘‘fundamental experiment.” It consists in measuring the successive differences of potential (cross differences) which present themselves between two opposite points on the upper and on the under surface of one lobe of the leaf, during periods which precede, include, and follow the moment at which the opposite lobe is mechanically or electrically excited. In this experiment it is found that, provided that the conditions are favourable to the vigour of the leaf, the variations of the cross difference (called the excitatory variation) occur in the following order :— Before excitation (particularly Upper surface negative to if the leaf has been previcusly under. excited). At the moment of excitation. Sudden negativity of wnder surface, attaining its maximum in about half a second, when the difference amounts to not less than #; Daniell. After excitation. Rapidly increasing negativity of the wpper surface, beginning about 1:5” and culminating about 3” after excitation, and slowly subsiding. This subsidence is not complete, for, as has been said, the lasting difference between the two surfaces is augmented—the upper surface becoming more negative after each excitation (‘‘after-effect ’’). When by a similar method two points are taken for comparison on opposite lobes, the phenomena are more ‘complicated, but admit of being explained as resulting from the more simple case above stated, in which only a few strata of cells are interposed between the leading off electrodes. In Part V the relation of the leaf to different modes of excitation is investigated. As regards electrical excitation the results are as follows :—If a voltaic current is led across one lobe by non-polarisa- ble electrodes applied to opposite surfaces (the other lobe being led off as in the fundamental experiment) a response (excitatory variation) occurs at the moment that the current is closed, provided that the strength of the current is adequate, and not much more than adequate. No response occurs at breaking the current. When acurrent of more than adequate strength is used, and its direction is downwards, the response at closing is followed by several others. This effect does not happen when the current is directed upwards. To evoke a response a current must be much stronger if directed upwards than if directed downwards through the same electrodes. Weak currents cease to act when their duration is reduced to ;34,,; for stronger ones the limit is 1881.] On some Effects of Transmitting Electric Currents. 151 shorter. Inadequate currents, if directed downwards, produce nega- tivity of the upper surface, which lasts for several seconds after the current is broken. This effect is limited to the surfaces through which the current is led. Its direction showsit is not dependent on polarisa- tion. By opening induction currents, if their strength does not much exceed the limit of adequacy, a leaf may be excited at intervals for several hours without failure. Weaker currents are more effectual when directed downwards than when directed upwards. If two inade- quate induction currents follow one another at any interval less than O'-4 and greater than 0°02, they may evoke a response. In this case a response follows the second excitation. When a leaf is sub- jected to a series of induction currents at short intervals (,3,”) the response occurs after a greater or less number of excitations. If the temperature is gradually diminished, the number is increased by each diminution. All of the above statements relating to excitability refer to plants kept in a moist atmosphere at 832—35° C. From the preceding facts, and others which are stated in the paper, the author infers (1) that the ‘ cross difference” is the expression of electromotive forces which have their seat in the living protoplasm of the parenchyma cells, and that it is due to the contact of cells in different states of physiological activity; (2) that the second phase of the excitatory variation is probably dependent on the diminution of turgor of the excited cells, and therefore on the migration of liquid ; (3) but that no such explanation can possibly be accepted of the phenomena of the first phase, the time relations of which, particularly its sudden accession and rapid propagation, show it to be the analogue of the ‘‘negative variation” or “‘ action current’’ of animal physiology. IJ. “On some Effects of Transmitting, Electric Currents through Magnetised Electrolytes.” By Dr. G. Gorg, F.R.S. Received November 29, 1881. (Abstract.) This communication treats of a class of electro-magnetic rotations observed and examined by the author. The rotations are produced in liquids by means of axial electric currents, either in the interior of vertical magnets, electro or permanent, or near the pules of such magnets, and differ from rotations previously produced in liquids placed in those positions, by the absence of radial currents, to the VOL. XXXIII. M 152. Dr. G. Gore. On some Effects of Transmitting [Dec. 15, influence of which rotations in the interior of hollow- rman have hitherto been ascribed.* It is here shown that a column of an electrolyte placed under similar conditions to an iron wire or rod, when subjected to electro-magnetic torsion (i.e., enclosed by an electro-magnetic helix, and traversed axially by an electric current), is twisted in a similar manner to the wire or bar. This effect, however, in the case of a liquid is not limited to paramagnetic substances, nor is the direction of torsion altered by the magnetic character of the liquid. The rotations produced in liquids by means of axial currents are opposite in direction at the two ends of the voltaic helix, are strongest at the poles, and at a little distance beyond them, and null at ahs centre of the tube; they may be produced at a distance of several inches beyond the poles. The directions of rotation within the tube, and to a short distance beyond the poles, are in the case of an electro or permanent magnet opposite to those produced by a voltaic selenoid. A magnet tube, therefore, has three points of no rotation with an axial current, viz., one at its centre, and one near each end, whilst a selenoid has only the former one. The existence of the outer neutral points produced by a magnet depends upon the position of the latter to the liquid, and the distances of those points from the poles of the magnet are affected by various circumstances, which are described in the communication. If the magnet is wholly above or below the portion of liquid traversed by the axial current, the outer neutral points do not occur. By the influence of a vertical current, the liquid as a whole may be made to rotate in either single direction; the motion at one end of the column, therefore, is not dependent upon the opposite direction of motion at the other, and torsion is not a necessary form of the effect. The reaction of the liquid in the production of the rotation is neither upon another portion of the liquid, nor upon the electrodes, nor upon the walls of the containing vessel, but upon the adjacent magnetised body, and the rotation of the liquid is confined to the portion traversed by the vertical current. Under suitable conditions, the phenomenon of rotation is definite, conspicuous, and strong, and is usually more powerful with a tubular electro-magnet than with a voltaic coil alone. A very thin iron tube weakens the effect of the coil, whilst a thick one reverses the motion and makes it stronger. The system of rotations, either with a coil or magnet, is also perfectly symmetrical. The directions of rotation produced by a coil alone are independent of the magnetic nature of the wire of the coil. Like other electro-magnetic effects, the rotations are not prevented by the interposition of metallic screens, provided * In the full paper it is stated that ‘‘ The whole of the results may be explained by the well-known principles of electro-magnetism.”’ 1881.] Electric Currents through Magnetised Electrolytes. 153 they are non-magnetic. The rotations may be easily produced by the aid of a current from three or four Groves elements, especially if permanent bar-magnets are used instead of a voltaic coil. The rota- tions by means of vertical currents in the liquid may be produced by the influence of coils or magnets, either above or below the liquids, as well as around it; with magnets, however, in the former positions, no external reversal points occur. A magnet placed entirely above or below the liquid produces the same direction of rotation as a coil placed either above, below, or around it. The direction of rotation produced in a liquid above or within a coil by an wpward current in the liquid agrees with that produced by a radial centripetal one within the coil. A rotation apparatus of the same kind, interposed as a screen, does not prevent or appear to affect the movements. Hach electrode may be made to separately revolve in the presence of a coil or magnet by the well-known influence of the radial currents in them; and the directions of rotation are the same with a tubular magnet as with a coil. In this respect the motion produced by radial currents differs from that produced by axial ones. With each elec- trode diverging currents within the coil or magnet produce dextro, and converging ones levo, rotation when the north pole is above. The rotation of the electrodes by means of radial currents appears to be independent of that produced in the liquid by means of axial ones. The rotation also of the vessel containing the liquid may be obtained independently of that of the electrodes, by means of the vertical current in the liquid, without the aid of the radial currents in the electrodes. The rotations produced by a vertical axis current are not confined to liquids, but may also be produced in a solid conductor, and probably, therefore, with any body conveying an electric current or discharge. If we regard a coil as a collection of currents, with a vertical current proceeding upwards or downwards from the centre of the coil, either on its inside or outside, the flow of the liquid is in the same direction as the current in the coil; and similarly with a vertical current pro- ceeding in like manner from the central parts of a tubular iron or steel magnet, the flow of liquid is in the same direction as that of the nearest layer of hypothetical electric currents in the iron. The directions of rotation produced in liquids by means of radial currents inside a magnet or coil are the same as in the solid electrodes, and are lzvo at all positions with centripetal currents, and dextro with centrifugal ones, when the north pole is above. A given direction of radial current, whether in the electrodes or electrolytes, or above or below a given pole, provided that the -pole was not reversed in posi- tion, produced the same direction of rotation. The direction of rota- tion produced by a radial current approaching a vertical coil or magnet M 2 154 Mr. J.N. Lockyer. Preliminary Report to the [Dec. 15, from the outside is the same as that produced by such a current approaching it from the inside. Various other phenomena, such as temporary reversals of the direc- tion of rotation, successive action of the coil and iron tube, &e., &c., are recorded in the paper. With a Selenoid.—An axial current flowing upwards from a south to a north seeking pole, produces dextro rotation at the former and levo rotation at the latter. With.a Tubular Magnet.—These two directions are reversed at all distances between the two neutral points near the poles of the magnets, but not beyond. The phenomena, therefore, of rotation are more complex with a tubular magnet than with a selenoid. The directions of rotation produced by a vertical current outside a vertical coil or magnet are the same as those produced by it inside a coil alone. The reversals of direction of rotation near the poles, which. occur when a tubular magnet is employed, appear to be due to the inner surface of the magnet, and to the position of that surface in relation to the vertical current in the liquid. The direction of rotation and the points of reversal appear to be all independent of each other. The action of radial currents is more simple than that of axial ones, especially near the poles of a magnet. With radial currents, either in the liquid or electrodes, there is no reversal, either at the centre of the magnet or coil, or at the poles or beyond them, or near the outside of the coil or magnet. 3 The experiments show the entire group of rotations produced inside and outside a vertical coil (with and without an iron core), and near its poles, by radial currents; also the group of rotations produced by vertical currents inside and outside a vertical coil and near its poles, and also those produced inside and outside and near the poles of a vertical coil with a tubular iron core, by such currents. The experiments show in a conspicuous manner the difference of property of the interior surface of a hollow magnet and of that of a voltaic selenoid having the same kind of poles at their corresponding ends. This difference of property is well known, but is illustrated in the paper in a new way experimentally. III. “Preliminary Report to the Solar Physics Committee on the Sun-spot Observations made at Kensington.” By J. N. LockyER. Communicated to the Royal Society at the re- quest of the Solar Physics Committee. Received Novem- ber 29, 1881. Since the commencement of the observations, in November, 1879, of the twelve most widened lines in sun-spots, about 220 observations have 1881.] Solar Physics Committee on Sun-Spot Observations. 155 been made; the maps for the first and second hundred observations have been drawn up and the tabulation of the first hundred completed. The reductions are being carried on, and I hope shortly to be able to lay a full report upon the 200 observations before the Committee, but desire, in the mean time, to bring the present preliminary one before it. The reduction of the first hundred observations, extending from November, 1879, to September, 1880, has yielded the ‘gl avrmne re- sults :— 1. An immense variation, from spot to spot, is to be Peoniea between the most widened lines seen in the first hundred observations. Change of quantity or density will not account for this variation. To investigate this point I had the individual observations of lines seen in the spectrum of iron plotted out on strips of paper, and I then tried to arrange them in order, but I could not succeed, for even when © the observations were divided into six groups about half of them were left outstanding. 2. If we consider the lines of any one substance, there is as much inversion between these lines as between the lines of any two metals. By the term inversion I mean of any three lines A, B, C, that we may get A and B without C, A and C isvout B, B and C without A, and SO on. 3. We have reason to believe, from experiments made here, that most of the lines seen in the spectrum of iron volatilised in the oxy- hydrogen blowpipe flame are amongst the most widened lines. 4, Certain lines of iron have been seen at rest, while other adjacent lines seen in the spectrum of this metal in the same field of view have shown change of wave-length. 5. The spectrum of iron in the solar spectrum is more like that of the arc than that of the spark. 6. The greater part of the lines seen in spots and flames are common to two or more substances with the dispersion employed. 7. The first hundred spot observations being compared with a hundred observations of the spectra of flames, made by Tacchini at Palermo, have shown that there is no iron line in the region b-F common to spots and prominences. In addition to these facts, already communicated to the Committee in more or less detail at different times, the following have been noticed in the continuation of the reductions. 8. The lines cf iron, cobalt, chromium, manganese, titanium, calcium, and nickel seen in the spectra of spots and flames are usually coincident with lines in the spectra of other metals, with the dis- persion employed, whilst the lines of tungsten, copper, and zine seen in spots and storms are not coincident with lines in other spectra. 9. The lines of iron, manganese, zinc, and titanium most frequently [Dec ta; Report to the 4 Preliminaa Lockyer. ING J ousas AN baal te IC sal Te all tl a Ene on a hi Cy = ee Mr. - Ke os 3 Ti ea a TI Lo goa: a ia a ane = =- 65 / g vs 0g fae , a ae | Saad am 156 1881.] Solar Physics Committee on Sun-Spot Observations. 157 seen in spots are different from those most frequently seen in flames, whilst in cobalt, chromium, and calcium the lines seen in spots are the ssame as those seen in flames. 10. Towards the end of the first series a few lines appeared among the most widened ones which are not represented, so far as is known, among the lines seen in the spectra of terrestrial elements. This change took place when there was a marked increase in the solar activity. ; So much for the results from the first series of observations. The second series began on 29th September, 1880, and comes down to October, 1881. From a partial reduction of the observations the following results have been obtained :— 11. The number of new lines seen amongst the most widened lines has been steadily increasing. Many of these lines are very faint in the solar spectrum, and are unrecorded by Angstrom, while they are wide and dark in the spot-spectrum. -12. In the months of May and June of this year (1881), there was a great change in the spectra of the spots, the old lines dying out and new lines appearing. 13. When series of observations, consisting of ten consecutive observations of the spectra of spots, taken from the commencement of the first series in November, 1879, and from the end of it on 27th September, 1880, were compared with those made towards the end of the second series on 18th July, 1881, it was found that the lines widened in each set were markedly distinct from those in the other Sets. ; To illustrate this, | have prepared the diagram opposite. At the top are some of the principal Fraunhoferic lines in the region F to D, the lengths representing the intensities. The lower part of the diagram is divided into three sections by strong lines; the first of these (1—10) contains the observations made between November 12, 1879, and January 20, 1880, the second (11—20) the observations made between September 27 and October 1, 1880, and the third those -amade between July 18 and July 29, 1881.* * The dates of the observations and the Greenwich numberings are as follows :— No. Date. Greenwich No. DR re hiss November 12,1879 ........ 7 ee Ae ae =, MSs aa AS 4 ” 27, » ARE Ea aihellote 93 FAS nee I Sy a January 3, 1880 7 nea % POE Aha 301 8 ss Oy 306 9 z = ie ep 306 158 Mr. J.N. Lockyer. On Sun-Spot Observations. [Dec. 15, 14. At the commencement of October, 1881, there was a change in the spectra of the spots similar to that which took place in May and June, but much more abrupt, for only one of the old nes remained. This is exactly analogous to the variations Tacchini saw in the spectra of the prominences in the region F to b, in December, 1872. 15. In the first series of observations the total number of most widened lines in the region F to b was fifty-seven, forty of which were due to iron, whilst in the second series the total number of lines seen was 104, and the iron lines faded away gradually, the last dis- appearing on 26th July, 1881. 16. So far as the observations have gone there has been no dif- ference caused by the nearness of the spot to the hmb. 17. At the present time more than 75 per cent. of the most widened lines are not represented in the spectra of terrestrial elements. 18. A line of titanium at wave-length 5865°0 and a line of barium at wave-length 5852°5 are amongst the recent most widened lines. Both these are long lines in the spectra of these metals. The line at wave-length 5852°5 has been seen by Young in flames, with a frequency of eight. No. Date. Greenwich No. 10 .cuesce Sanuary e920 1 SS0Ri. esc. ooG fo sc ahoniaes CPUC MIDE Ay ars erect at 367 We wena ds 28 as Ba Se ae ae 367 Le ie epee ns 78 i ae ae ae 368 14 ee eee 370 1S Mids, Lhe Fe 505,55; OF Peas 367 1G eee MUSE Corus cick AZ | ctnyetoge rc oe s SOsP <5; Je looeeeee 370 18" tee ceuee pOctoner 1 eae Bee 367 UD) SARA cia - ieee. aCe 368 ZO" PREC BS eee ee 370 ALE magnckss idly; 18, 1881 4 76 EAPO Ra, eS [ois A” Sener ear 521 De? cpg Nite wea Biker eae 521 DAWN Groves oiaiske eS 2) Melee sidouaetetete 525 Oe aie ts Ghee Fe 26; --,, eras 6s 529 OG Ve oct ee ee 2 ee RDS 27 i DSi. 6 are 28 if eet 275 29 ie BS Ilan. ancien cise eeage 527 BOs len tenco ee st 29. ot sa ae 1881.] Mr. C. G. Williams. On 8-Lutidine. 159 IV. “On #-Lutidine.” By C. GREVILLE WILLIAMS, F.R.S. Received November 30, 1881. In the “ Bulletin of the Chemical Society of Paris” for June 5, 1880 there appears a notice of a paper read before the Russian Chemical Society, by MM. Boutlerow and Wischnegradsky, in which they state, among other things, that by the action of alkalies on cinchonine they had obtained quinoline (chinoline) almost pure, and a volatile colourless liquid alkaloid boiling constantly at 166°, having the formula C7HPN ; and which they say appears to be identical with the base obtained by me in distilling cinchonine with potash, and also with the lutidine of Anderson. Of the identity of the base obtained by them with (6-luti- dine there can be no doubt; the boiling point (166°) given by them being to half a degree the mean of the range (163° to 168°) given by me in my “ Researches on Isomeric Alkaloids.’’* With regard to the identity which they assume between lutidine and ~ 6-lutidine, it is evident that they have not seen my paper last quoted, or they would hardly have ignored the mass of facts which I have adduced to prove the isomerism, and not identity of the two bases. In the “ Bulletin of the Chemical Society ” of Paris, Nos. 5 and 9, for September 5, 1880, p. 210, M. W. Oechsner de Coninck publishes an investigation on the lutidine, collidine, and parvoline obtained as above from cinchonine ; his only reference to my work being to the “Ann. Chim. Phys.,” xlv, p. 488,7 in which he says that I have shown the presence of a base possessing the composition of lutidine. He then proceeds to give analyses, density, and vapour-densities of #-lutidine, apparently unaware that they were simply repetitions of what I had done many years before. I gave the analysis of the hase and the platinum salt in the ‘‘ Trans. Roy. Soc. Edin.,” previously quoted. I also gave the analyses of the platinum salt of collidine in the same paper. The specific gravity of B-lutidine at 0° was given by me in my ‘“‘ Researches on Isomeric Alkaloids” as 0:9555; M. de Coninck makes it 0°95035 at the same temperature. M. de Coninck gives the. vapour-density as determined in Von Meyer’s apparatus as 3°80; I gave it as 3°65 in two experiments exactly agreeing with each other, and also made in Von Meyer’s apparatus.t The formula C7H?9N requires 3°699. In my paper “On Isomeric Alkaloids” I gave as the- result of a determination by Dumas’ method 3°787. M. de Coninck also states as a new result that the platinochloride of the lutidine- * “Proc. Roy. Soc.,” vol. 18, p. 305, June, 1864. + This is a précis of my paper, “On the Volatile Bases produced by Destructive Distillation of Cinchonine,” “ Trans. Roy. Soc. Edinburgh,” xxi, part u, April, 1855. ~ “Chemical News,” March 14, 1879. 160 Mr. C. G. Williams. [Dec. 15, from cinchonine is modified by hot water, losing two molecules of hydrochloric acid. The extraordinary difference between the decom- posability of the platinum salts of lutidine and (§-Iutidine on boiling with water with evolution of hydrochloric acid, was one of the numer- ous illustrations of the isomerism of the two bases which I adduced in my ‘‘ Researches on Isomeric Alkaloids” seventeen years ago. The tone of M. de Coninck’s paper shows that he believes his results to be entirely new. I mention the above facts partly because they are facts, but, chiefly as showing that other chemists are working on f- Intidine, and that it therefore becomes necessary to publish my more recent experiments somewhat earlier than I should otherwise have lone. The preparation of 8-lutidine in a state of purity is a work of much labour. On distilling cinchonine with hydrate of potassium a mixture of at least ten alkaloids is obtained, and the #-lutidine has to be separated by fractional distillation. J have, however, prepared for the purposes of this investigation probably the largest quantity of the base that has yet been obtained—rather more than half a pint. Action of Sodium upon B-Liutidine. I found that by the action of sodium upon chinoline it became polymerised with the formation of a body having the composition of dichinoline. This substance forms a crystalline hydrochlorate, having, when freshly prepared, a magnificent scarlet colour.* The hydro- chlorate of dichinoline dyes silk a brilliant but fugitive orange colour. This reaction, namely, the formation of a coloured hydrochlorate from a colourless oily base, being probably unique, it became desirable to ascertain how f-lutidine would behave under similar circumstances. Fragments of sodium were added to #-lutidine in the cold; they acquired a brilliant yellow colour, and had exactly the appearance of pieces of metallic gold. The mixture was then warmed until the sodium melted, it was then removed from the lamp. A violent reaction ensued, and the whole turned greenish-black by reflected light, and yellowish-brown by transmitted light. The product was left until the next day, and was then boiled for five minutes; it thickened, and, on being poured into water, yielded a heavy brown oil. No pyrrol was formed. Excess of hydrochloric acid being added, the oil dissolved, forming a brown solution; this was fractionally precipitated with solution of platinic chloride. Six precipitates were obtained; the first was pale brown, the second fawn-coloured, the third a paler fawn, the fourth Naples yellow, the fifth sulphur- yellow. The last only was distinctly crystalline under the lens. If put in a wet state into the water-oven they melt, but, if first dried over * “ Chemical News,’ March 1, 1878; “ Proc. Roy. Soc.,” vol. 31, p. 536. 1881.] On B-Lutidine. 161 sulphuric acid, the desiccation may be completed without fusion. The platinum was determined separately in the first four precipitates; the fifth and sixth were so small in quantity that they had to be mixed. Number of precipitate. Percentage of platinum. ee saya ni atar al afi ayidy yay inte 25°28 TE apeaiay aceidchavaterspncey'e 2482 TE tay Bears cpa cs Seenay dale 26°40 Nein tah stoned art ok arenes 27°57 IVES aC ON pea. haps onda deed d onays 30°28 The second precipitate; in its percentage of platinum, agrees with the formula for the platinum salt of the hydrochlorate of dibetaluti- dine containing two molecules of dibetalutidine, the formula being— 2(CM4H!8N?) HCL PtCls or, of a still higher polymer, in which case the formula becomes— C8H36N4 HCLPtCl; whichever formula we adopt, the percentage of platinum required is 24°61, which agrees closely with the experimental number. The other precipitates were probably mixtures of this salt with the platinum salt of dibetalutidine— CUuHISN?, HCLPtcl, which requires 33°53 per cent. of platinum. ‘A second preparation was then made, but the oil obtained on treat- ing the crude product with water was distilled; the boiling point varied from 180° C. to a temperature above the range of the mercurial thermometer. Four fractions were received, the fourth, which dis- tilled at and above 300°, was dissolved in hydrochloric acid, and frac- tionally precipitated with platinic chloride. Number of precipitate. Percentage of platinum. LM ey ic rah ace sate oevsy Ss Lost. HI SPR cus ev wee ot 24°69 i i to EH aa 26°48 JO Ml edict i sas ma 29°60 The second precipitate, therefore, afforded almost exactly the numbers required for the salt C?®H°°N*HCI1.PtCl4, and the others were probably mixtures of the kind I have indicated above. It is possible that the fourth precipitate had the composition shown by the formula C!4H'N?.3HC1.PtCl4, which would require 29°84 per cent. of platinum; I propose to settle this question by further experi- ments. 162 3 Mr. C. G. Williams. [Dec. 15,. During the precipitation of the platinum salts from the distilled base the solution became of a brilliant but fugitive scarlet colour. It is evident from the above numbers that the oil of high boiling point had the same general character as the crude mixture first examined. Sodium amalgam, although it so readily polymerises chinoline,* was found to be almost without action on #-lutidine. The action of sodium was then tried upon f-lutidine dissolved in toluene; two products were obtained, one solid, the other liquid. The solid substance on being dissolved in hydrochloric acid, and fraction- ally precipitated as before, gave two precipitates. Number of precipitate. Percentage of platinum. I SRR coerce era 25°30 TEES. Se ceed, Sete eee 33°33 The fluid portion treated as before gave— Number of precipitate. Percentage of platinum. I hese enone a neeiereaboenes 26°14: 1 Ea COR trey cre A 30°69 The results, while proving that f-lutidine is polymerised by the action of sodium, show also that at least two substances are formed, and that separation is not easily effected by fractional precipitation with platinic chloride. It will be seen that the second precipitate from the hydrochlorate of the solid base gave for the platinum a number almost exactly agreeing with that required for the platinum salt of dibetalutidine C!4H'*N*,HCIPtCl4, which requires 33°53 per cent. of platinum. Compound of B-Lutidine with Nitrate of Silver. I have shown in my paper ‘‘ Researches on Isomeric Alkaloids,’ + that f-lutidine combines directly with platinic chloride; it does the same with nitrate of silver. When #-lutidine is added to an aqueous solution of nitrate of silver, a white curdy precipitate is thrown down, it dissolves in alcohol, and is reprecipitated by water as a glittering mass of snow-white crystals. These latter crystallise readily from alcohol in beautiful stellar groups.. On analysis the following numbers were obtained :— * “ Proc. Roy. Soe.,’ vol. 31, p. 536. 7 “Proc. Roy. Soc.,’ vol. 13, p. 308. There is a misprint in this paper, the formula for the direct compound of @-lutidine with platinic chloride is given as C7H°N.PtCl, it should have been C7 H9N.PtCl? ; or, in modern notation, (Pt =198) 2(C7H9N) PtCl?. 1881] On B-Lutidine. (les Experiment. Calculation. (= as a Carbone ch 50°97 61°32 C74) 252 Elyvdrogeniyis. ste bet: 5°98 Deo Opal sce 217 INTO RENIN Pleo nts a: hee a ONS 56 Oxcy creme Way ah ce ot ay ect 0:78) 30?) 48 Sulliver see mitre ie ab sists 21°03 ZOO Ae Ads 100-00 491 agreeing with the formula— 3(C7HPN).Ag.NO®. Compound of Hydrochlorate of B-Lutidine with Chloride of Uranyl. On mixing solutions of hydrochlorate of B-lutidine and chloride of uranyl, a beautiful yellow salt is formed; it gave the following numbers :— Experiment. Calculation. SS Seder seeage ae 26-90 2667 CM 168 EVGdrO@eD 6042. a.» « 3°39 Sly BEY AA) iNAiirogern sets Ar4d N? 28 @Whitorime... 42% si. ce> roe Dor oAn Ola, TA Wreammnurialits.c pects. pe 38:10 Ur? 240 Oey ROMA fois sino oye seh 5°08 O? 32 100°00 630 agreeing with the formula-— 2(CTEPN.HCl).Ur°0°CL. Compound of Sulpnate of B-Lutidine and Sulphate of Uranyl. On mixing sulphate of uranyl with sulphate of -lutidine a yellow mass consisting of small crystals is formed on long standing. The substance was dried at 100°, and burnt with the annexed result :— Experiment. Calculation. (ea EE @ amOME tee es 56 ass 19°10 Nera OE Jes iydvOgen. 0.2... >. 2°54: PS) Ise AY) INFLMOMEME ca. as 3s See 321 N? 28 Sullplame ee he Ses ste 1468 S* 128 Wiranturia et..." ee 27°52 Ux? 240 Operon wees ae sh, Bode 33°03 O18 288 100-00 872 The above numbers agree with the formula— 2(C7H2N) H2S804.Ur202.3(S04). 164 Capt. Abney. On the Effect of the [Dec aise Picrate of B-Lutidine. When £-lutidine is added to a strong boiling solution of picric acid, most of the salt formed settles out as an oil, owing to its insolubility and fusibility, but it becomes a solid crystalline mass on cooling. On redissolving the solid in boiling water, and allowing the solution to cool, the vessel becomes filled with brilliant yellow needles. They were burnt with oxide of copper, with the necessary precautions, and gave the following numbers :— Experiment. Mean. Calculation. Weeboneee. ae 46°77 46°75 4680 46:77 ‘4648 CB 156 Hydrogen..... All . 416, 3:94 - 407°) 357 qa Nitrogen ’...... cece Sidi, Dae emen weaeter ence 16°67. N26 Oxy Cen 9. cays «coca hg Ae Or ae eae Joe 33°33 OT 112 100-00 336: The formula is, therefore— CSH?2(H.C7H°N)3(NO2).0. Action of Chlorine on B-Lutidine in presence of Iodine. The chlorination of B-lutidine was effected by Hugo Miiller’s method ; for this purpose iodine was added to the alkaloid, the mixture was heated to 100°, anda current of chlorine was passed through until com- plete saturation. The product was a dark reddish-brown fluid, which was distilled. The portion boiling below 220° was washed with a dilute solution of hydrate of sodium, and then treated with hydrochloric acid, a viscid green substance of peculiar odour remained undissolved. On adding solution of platinic chloride to the filtered liquid, a granular precipitate was obtained; it was washed, dried, and the per- centage of platinum determined: it amounted to 23°49 per cent. The formula 2(C7H®CIN.HC1)PtCl* requires 23:74. This result shows that the product is a trichlorinated -lutidine retainmg the basic properties of the original alkaloid. V. “On the Effect of the Spectrum on the Haloid Salts of Silver, and on Mixtures of the same.” By Captain ABNEY, R.E., F.R.S. Communicated to the Royal Society at the request of the Committee on Solar Physics. Received December 6, 1881. There have been many investigations as to the sensitiveness to the spectrum of the haloid salts of silver, from the very earliest days of photography ; and when the results obtained by the different investi- 1881. ] Spectrum on the Haloid Salts of Silver, &c. 165: gators are compared one with another there are often very wide discrepancies apparent. It appeared to me that it was desirable if possible to examine the subject afresh, and to endeavour to reconcile or to explain as far as possible these discrepancies. The earlier investigators, such as Herschel, Hunt, Draper, and Becquerel, added much to the knowledge of the subject, but their researches were carried on at a time when the modern modifications. and more powerful means of development of an image were unknown. Later investigators, including such eminent names as H. W. Vogel and Hder, have availed themselves of the modern appliances, but their results are not always consistent one with another. In the following researches points are brought out which are, it is believed, new and deserving of attention, not only on account of their applicability to the practical working of photography, but also because they throw a light on molecular physics. For solar photography it is essential that a knowledge of the relative effect of the various parts of the spectrum should be known, since, if the photo-heliograph be adjusted for one particular part, and the films employed be more sensitive to another part, it is manifest that no great sharpness of image can be obtained. The following researches it is believed show what an enormous effect the mixture of haloid salts has in shifting the position of maximum effect, and it may be possible to either alter the achromatism of the objectives employed, or else solely to use the sensitive compound to which the objective is at present adapted. Apparatus employed.—The spectroscope employed in these researches was that already described “‘ On the Hffect of the Atomic Grouping of Molecules.” * Two prisms of medium dense and colourless flint- glass were used to obtain the necessary dispersion. They were set to have the angle of minimum deviationnearG. The angle of disper- sion between A and H was about 64°, the length of spectrum between these two lines was about 27 inches, the spectrum in the ultra-violet extending some 14 inch beyond H, and the infra-red about ¢ of an inch beyond A. The whole spectrum as given by the prisms under consideration thus had:a length of 44 inches, a length in which all phenomena could be fully recognised and measured. Sources of Inght——The sources of light employed were the sun and the crater of the positive pole of the electric light. Images of these sources were thrown on the slit by means of a condensing lens alone in the second ease, and by it and a heliostat in the first case. Vehicles holding the Sensitive Salts—The sensitive salts were held wm situ, in paper, in gelatine, and in collodion, in the last vehicle the salts being prepared either as emulsions in fluid collodion or by the ordinary silver nitrate bath process. In gelatine the salts were all abil Pranss; for 188); Rart:3: 166 Capt. Abney. On the Effect of the [Deermiis: prepared as emulsions; when in paper they were prepared by soaking it ina soluble haloid salt, and floating on solution of silver nitrate. The question of the production of sensitive silver haloid salts on a metallic silver plate I have left to be considered later, since it has no direct bearing on the points I wish to discuss in this communication. Exposures.—When it was desired to obtain the expression of the action of the spectrum by its direct effect without the intermediary of a developer, the slit of the spectroscope was opened to a width of zy of an inch, and the exposure prolonged for five to twenty minutes. When the effects had to be shown by development the slit was closed to 345 of an inch, and exposure given varying between + second and one minute oreven two minutes. By having a shutter at the slit of the spectroscope it was easy to give two exposures on the same plate or paper, using half the length of the slit for each exposure. This was excessively convenient, since it allowed the different phenomena arising from different methods of exposure to be accurately compared together. The principle on which the exposures were given was as follows :— Ist. An exposure was given to the plate, when a pale solution of chro- mate of potash so dilute as to cut off the spectrum above H, was placed in front of the shit. This exposure was in all cases prolonged in order to see if there was any action produced, however feeble, by the spectrum remaining unabsorbed. The next exposure was always taken with the slit unshaded, and on the same plate (or paper) as the first exposure. After a certain interval of time had elapsed, the yellow chromate was again placed in front of the slit, and the exposure continued. The reason for adopting this plan was that the effect of diffused white light (diffused from the prisms during unshaded exposure) would thus be differentiated: Thus, supposing it was found that the first exposure caused no sign of a change in the sensitive salt by the exposure to the spectrum unabsorbed by the chromate, but that the unshaded spectrum caused an action on these parts, 1t would be evident that the action of diffused light had played a part in causing such an action. When such phenomena resulted, plates or papers were first exposed to the unshaded spectrum through the chromate solution, then with- drawn from the camera and exposed to the diffused light of the laboratory for a fraction of a second, or for eight or ten seconds, accord- ing as the experiment was to be conducted by development or by direct printing action, and again inserted in the slide and exposed to the action of the partially absorbed spectrum. If the experiments were rightly conducted, the results of the last two should be con- firmatory of the first two exposures. Other plates or papers were then exposed, giving, unshaded, one half of the slit of a short period, and the other half for a period teu to twenty timesas long. By this system all the phenomena met with could be differentiated and traced. 1881. ] Spectrum on the Haloid Salts of Silver, Se. 167 Localities of Maximum Action—I have followed the usual custom of writers on this subject, and shown the top of my curves as the place of maximum action. Although this correctly shows what appears on the photographic plate, yet in all cases it is apt to givea false notion regarding the effect of the spectrum. If we look at the energy of the spectrum in its different localities, we find that it rapidly decreases as it approaches the violet and ultra-violet. If this diminution of energy be taken into account, it will be found that usually the point of maximum effect nearest the violet indicates the region where the absorption of the rays becomes total, and that the shading off towards the ultra-violet is really only due to the diminished energy of that part of the spectrum. In other cases, as, for instance, where there are two maxima, this will not apply to the second maximum. Silver Iodide. Visible Effect of the Spectrum on Silver Iodide.—If paper be soaked in a 10 per cent. solution of potassium iodide and dried, and then be floated on a 10 per cent. solution of silver nitrate and exposed whilst moist,* the spectrum will be impressed in five minutes, as given in fig. 1, where it will be seen that the whole visible spectrum is impressed. Similar paper if exposed to the spectrum coming through a weak solution of potassium chromate, exhibits after ten minutes a — slight action in the least refrangible region (fig. 3). If, however, the paper be exposed for ten seconds to diffused ight and then be exposed to the same spectrum as the last the action is more intense than betore, though the exposure be for only two minutes (fig. 2). From this we learn that part of the action of the spectrum in fig. 1 is due to the action of diffused light. It next remained to trace the action on the different silver compounds existing in this paper, which was ordinary sized saxe paper. Paper was prepared as before, but washed in common water till nearly all excess of silver nitrate was eliminated, and it was then given a wash of potassium nitrite, an absorbent of iodine. Such paper was exposed to the spectrum, first, coming through chromate, second, unshaded. The print obtained is that shown in fig. 4, by which it will be seen that the same limits were reached as before, but that there is not that abrupt descent of sensitiveness near G; evidently some cause of the extreme sensitiveness near this point had been eliminated, and apparently that could only be the silver nitrate and the presence of the potassium nitrite. To test the matter further, paper was prepared in the same manner, but before applying the potassium nitrite it was soaked in common salt and water and washed. This would effectually remove all traces of silver nitrate * 'The same action was observed where the paper was allowed to dry, but the darkening was less. VOL. XXXIII. N 168 Capt. Abney. On the Effect of the | Dec. 15, converting it into silver chloride. Exposure for five minutes to the spectrum gave the result shown in fig. 5, in which it will be seen that whilst the most refrangible portion took a grey colour, the small portion below G became a pink, the line of demarcation between the two being well defined. It now seemed probable that the pink part of the spectrum was due to the chloride and the grey to the iodide. To further investigate the matter, the same paper without iodide was floated on silver nitrate and exposed to the spectrum, with the result given in fig. 6, a very faint trace of action being visible where the paper was exposed for a quarter of an hour to the spectrum trans- mitted by the potassium chromate. Todised paper prepared as in the first experiment was well washed and simply exposed with the result to be seen in fig. 7. Finally, paper was prepared and washed, then immersed in a weak solution of potassium iodide, washed well and flooded with potassium nitrite, and the result is given in fig. 8. Now, fig. 1 coincides with the observa- tions made by Sir J. Herschel, on paper similarly prepared, in 1842, and described in the ‘‘ Phil. Trans.” for 1843, and he classes this spectrum as due to the silver iodide. I+ will be seen that the printed spectrum due to silver iodide is that given in fig. 8, and that the tail extending to the least refrangible end is really due to the action of _ that region on the organic salt (and perhaps chloride) of silver present in the paper. Further, it will be seen that the greater part of the darkening in fig. 1 of that tail is due to the action of the different rays after or whilst diffused light has acted or is acting on that organic compound. Confirmatory experiments were made with pure silver iodide in collodion with excess of silver nitrate, and also without such excess, with the result shown in fig. 8. If further confirmation were required, it was only necessary to add to a film of collodion containing the iodide and excess of silver nitrate a small trace of organic matter, such as resin or albumen, and the result given in fig. 9 was obtained. Thus, then, we may say that the parts of the spectrum capable of direct action on silver iodide are shown in fig. 8. The next point to which my attention was turned was to ascertain the true region of the spectrum which was active on silver iodide when developed. There are several developers for silver haloids :— lst. Ferrous sulphate and silver nitrate. Acid developers .. sted Pyrogallic acid < v3 3rd. Gallic acid Neutral organic iron f 4th. Ferrous oxalate. developers) y. >a 5th. Ferrous citro-oxalate. Alkaline developers 6th. Pyrogallic acid and ammonia. 99 3 1881.] Spectrum on the Haloid Salts of Silver, &c. I+AgNO, on paper Ano IED 4 IPO ee. Print. Aol on paper washed from Print. excess of AgNO, and treated with KNO,. gI on. paper washed from Print. AgNO, soaked in NaCl, washed from excess and exposed with KNO,. aper floated on AgNO, soet GUIs i AcT on paper washed from Print. excess of AgNO,, ruddy tint. ! ee ee AgI on paper washed from Print. excess of AgNO,, treated with KI and KNO,; or AgT in collodion. Agi+AgNO, inalbumen ... Print. mAcI prepared in bath treated Developed with KI, washed, redipped (long in silver bath, developed exposure). with pyrogallic acid. Ditto ditto ibe ees (short exposure). : | rt | { i —| t | | AgI purified and exposed in Developed presence of sensitiser, de- (long veloped by acid or alkaline exposure). developer. Ditto ditto asa <3 (short exposure), Ag! unpurified, treated and Developed developed as above. (long exposure). ditto ee och (short exposure). im Act with trace of AgCl or Developed f AgBr, developed by acid or (long alkaline method. exposure). ditto as wea (short exposure). gi + AgNO, in albumenised Developed. collodion, or on _ paper washed, acid development. me Act + AgNO, in albumenised Developed. fm = collodion, or on _ paper washed, ferrous citrate = §€«developer. we Aci+AgNO, prolonged ex- Developed. posure, n 2 170 Capt. Abney. On thé Effect of the (Dee: 15; Now, the first three gave precisely similar results as did the last three. It will, therefore, be unnecessary for me to state for every ex- periment which developer was used. With collodion or gelatine plates I preferred the 2nd and the 4th developers, and with paper the 3rd and the 5th. It may be necessary to point to the different materials employed. In the first place very pure potassium iodide was obtained by Stas’s method, and as much as would dissolve was put into collodion; by the free use of water with the alcohol as much as 4 grs. was dissolved. This was employed with a silver bath prepared in the usual way, con- taining 35 ers. of silver nitrate to each ounce of water. 5 grs. of commercial cadmium iodide was dissolved in an ounce of collodion, and this was also used with a silver nitrate sensitising bath. The pyroxylin forming the collodion was carefully selected. Before taking into use it had been precipitated from solution by water, washed in alcohol, again precipitated, and washed and dried, and then redissolved in equal parts of pure ether and alcohol at the rate of 7 grs. to each ounce. Such a solution after prolonged exposure when impregnated with nitrate of silver gave no reduction of the salt. The emulsions of silver iodide were made by dissolving 6 gers. of silver nitrate in alcohol, adding this to collodion, and gently adding the equivalent to 5 grs. of silver nitrate of the soluble iodide (dis- solved in alcohol) to it. This formed a perfect emulsion of silver iodide in the presence of a slight excess of silver nitrate, and also of course of the soluble nitrates formed by the double decomposition of the above. I may at once say that the presence or absence of these soluble nitrates had no effect at all on the results, and may at once be dismissed from further consideration. Gelatine emulsion was prepared in the same manner, keeping in mind, however, that in this case it was prepared with an excess of soluble iodide instead of silver nitrate. It is well to remark that it is impossible to get a fine emulsion of silver iodide in collodion unless the plan indicated above be followed of first dissolving the silver nitrate in the collodion and then adding the iodide to that, in addition to which it is necessary that the silver nitrate be in excess or the emulsion becomes granular. With gelatine the emulsification is an easier matter, but in order to prevent spontaneous decomposition of . the gelatine it is necessary that the soluble iodide be in excess. Emulsions of both kinds were ‘‘ washed ” by the usual methods known to photographers. In the case of the collodio-iodide of silver great care was taken that nothing but pure distilled water was employed. It will be well to show here how it was we ascertained that nothing but pure iodide of silver exists in a film. The impurities to be met with are oxides, chlorides, and bromides. Now when an oxide of silver, or silver chloride or bromide is placed in a solution of potas- 1881.] Spectrum on the Haloid Salts of Silver, ge. vel sium or other soluble iodide, the silver compound is at once decom- posed, and silver iodide formed in its place. If, then, a film of iodide of silver in collodion (whether prepared from an emulsion or by the bath process) be washed from silver nitrate, and be then im- mersed in a weak solution of potassium iodide (it must not be strong or it will dissolve out the silver iodide from the film) or other soluble iodide, it may be seen that there will be nothing but silver iodide in the film, all impurities being decomposed. If the film be washed well with distilled water, and again immersed in the bath, or flowed over with some sensitiser, such as potassium nitrite, sodium sulphite, beer, pyrogallic acid, &c., it may be exposed with the certainty that only pure silver iodide is under examination. It was necessary to make these remarks, since the whole of the utility of the research depends on the use of the pure substance, the collodion being absolutely inert as regards the silver salt. The silver iodide emulsion made from the purified potassium iodide proved to contain nothing but the pure iodide, but that prepared with the cadmium and other iodides, as will be seen, proved untrustworthy as to purity. It was owing to this that I was led into a mistake in a paper which appeared in the ‘“ Pro- ceedings of the Royal Society,” wherein I stated that owing to the oxygen-absorbing properties of potassium nitrite, I was able to obtain an image lower than ordinary. It seems now that this may have been due to a contamination of bromide or chloride, or to the formation of silver nitrate, any of which would have given me the same results. One word also as to the neutral or alkaline developer employed. Jt has been customary to state that silver iodide is unamenable to alkaline development. This is, however, not the case. The ferrous oxalate and the ferrous citro-oxalate bring out a distinct image, as does pyrogallic acid and ammonia, when no restraining iodide is employed. In all dry plates prepared with the iodide and other silver haloids, the iodide is developable (though it gives a weakly image compared with that due to other salts) by the alkaline or organic iron developer. A plate was coated with cadmium iodised collodion, and placed in the bath for a couple of minutes, and exposed to the spectrum. The top half of the slit was uncovered for one second, the bottom half for ten seconds; the results are seen in figs. 14 and 15. The develop- ment took place by the acid developer. Plates similarly prepared and washed, and then, similarly exposed, also gave as results figs. 14 and 15. When using ferrous oxalate, the cadmium emulsion also gave the same result. Plates coated with a film of the same collodion, washed, and then immersed in a weak solution of potassium iodide or cadmium iodide, again washed clean with distilled water, and finally treated with silver nitrate, beer, pyrogallic acid, potassium 172 Capt. Abney. On the Effect of the [Dec. 15, nitrite, when developed by the acid or other methods, gave the re- sults in figs. 10 and 11. The purification of silver iodide by this treat- ment cut off the small tail on the least refrangible side of G seen in fic. 14. When the pure silver iodide prepared by the aid of the pure potassium iodide was used, figs. 13 and 12 resulted. A plate was next coated with collodion iodised with the pure potassium iodide, im- mersed in the bath, washed, and then placed in a solution of common salt (1 gr. to 5 oz.), with the result that figures similar to figs. 16 and 17 were obtained. A plate similarly treated, except that potassium bromide was sub- stituted for the common salt, gave as a result figs. 16 and 17. There was no marked difference whether the plate was developed by the acid developer or by the ferrous oxalate. It would be useless to describe the many other experiments which were made, all tending to prove that the true action of the spectrum on silver iodide in collodion is that given in figs. 10 and 11. No deviation from it has been obtained, unless impurity in the pyroxyline or in the soluble iodide was proved to exist. With gelatine emulsions of yellow silver iodide, when rendered sensitive by the use of potassium nitrite or silver nitrate, the same action was found to hold good, and the same may be said for plates prepared with albumen as a vehicle, when all the silver was converted into iodide, and the sensitising was effected by potassium nitrite or some other similar sensitiser. We next come to the iodide of silver when held i situ by paper. -'The same method of preparation was adopted as that given above for the printing experiments. When paper was exposed with the excess of silver nitrate, on acid development fig. 18 was obtained. When developed by an organic ferrous developer, fig. 19 was obtained ; figs. 14 and 15 were obtained when similar paper was washed and salted with common salt, and washed again, and then sensitised with potassium nitrite. Figs. 18 and 19 are worthy of attention. It is seen in fig. 18 that the iodide has much greater power of attracting freshly deposited silver than have the impurities present with it in the paper. On the other hand, fig. 19 shows that the ferrous oxalate developer has more power of reducing the impurity (or rather the reduction is better seen) than it has the iodide. When silver iodide paper is prepared and washed, and treated with a weak solution of potassium iodide and resensitised by potassium nitrite, figs. 10 and 11 are obtained. Fig. 20 shows the action of the spectrum on pure iodide when the exposure is very prolonged. It appears as if the sensitiveness on the more refrangible side of G had diminished. This is not the case, however. The prolonged exposure causes a commencement of what is 1881. ] Spectrum on the Haloid Salts of Silver, &c. 173 called a reversal of the image due to oxidation, which I have already investigated in the ‘‘ Philosophical Magazine,” 1880, and the maximum effect has, therefore, apparently shifted to the least refrangible side of G, as shown. This is important, since phenomena which have been described and figured by other investigators can be shown to be caused by this reversing action. I shall have to allude to it myself again further on. What has been noted regarding the action of impurities in the silver iodide points to a method of ascertaining if an iodide or iodine itself is pure. It is believed that the merest trace of impurity may be recognised by this method of spectrum analysis. Silver Bromide. When paper is immersed in a 10 per cent. solution of potassium bromide, then dried and floated on a 10 per cent. solution of silver nitrate, and exposed to the action of the spectrum, the visible effect will be observed as shown in fig.21. Figs. 22 and 23 show the action of the spectrum after filtration through potassium chromate, the former being what is observed after a preliminary exposure to diffused white light, and the latter when the paper has only seen the yellow light. It is needless to go into all the details which were described when silver iodide paper was under examination. The same causes exist for the shape of the curve as they do with the latter paper. It may be interesting to remark that the spectrum observed on paper which has been washed and treated with potassium bromide after sen- sitising 1s the same as that shown in fig. 25, whilst when only washed and not treated with the soluble bromide it takes the form of fig. 29. The reason of these differences in shape of curve is apparent when it is remembered how the effects on silver iodide paper were traced to their source. It must be noted that there are several molecular modifications of silver bromide. The first is that form in which it exists in the paper and also in collodio-bromide emulsions when prepared in the ordinary way; also when prepared in collodion by the bath. This form transmits a yellow-orange tint when white light traverses it. Another form is one which I described in the Bakerian Lecture for 1880, viz. a form which transmits a blue-green tint; and a last form which transmits a grey tint, which is found in gelatine emulsions which have been boiled, or treated with ammonia in the manner which is common at the present day. These three varieties were examined both for the visible action of light and also for development. A plate was coated with the first emulsion named, with the result that the direct action of light gave fig. 25. The blue-green transmitting form gave fig. 24. This form is one which is sensitive to the infra-red rays of the spectrum on development, and it will be seen that the printing 174 Capt. Abney. On the Effect of the (Dec.ais; action also extended to that region. The printing action on the grey form (which was submitted to the spectrum in a film of gelatine) is shown in fig. 26. On comparing these together, it will be seen that the maximum action commences between G and F (nearer F than G), and that the main difference in their impressed spectra lies in the tails AgBr+AgNO,, on paper ... Print. “5 3 BAO a KOLO 5p ae sen TENG ireen AgBr in collodion with Print. m or without AgNO,. Mrange AgBr in collodion Print. im gelatine with or without AgNO. mirey AgBr in gelatine ... Print. gBr on paper washed from Developed AgNO,, developed with acid (long or ferrous citro-oxalate de- exposure). veloper. Ditto ditto Soc -. (short exposure). rey AgBr in gelatine, deve- Developed loped alkaline or ferrous (long oxalate. exposure). HIDitto ditto ose ea a Gore exposure). MOrange AgBr in collodion or Developed gelatine, developed alkaline (long ferrous oxalate or acid de- exposure). veloper. Ditto ditto ose sod (short exposure). Green AgBr in collodion, Developed developed ferrous oxalate. (dong exposure). iDitto ditto On .. (short exposure) on the least refrangible side. When the colour transmitted by these three forms is taken into account, these differences are to be expected. Whether the silver bromides were exposed with a slight excess of silver nitrate, or with a slight excess of soluble bromide, no difference in the spectra resulted. We next come to spectra developed on the different preparations of 1881.] Spectrum on the Haloid Salts of Silver, &c. 175 silver bromide. Fig. 27 represents the action of the spectrum on silver bromide paper, prepared as above, which has been washed. Whether development took place by acid developer or by ferrous citro-oxalate, no difference was observable. Fig. 28 shows the same with a short exposure. When the paper was washed and treated with potassium bromide and then exposed, we have as a result figs. 31 and 32. The slight difference in the pairs of figures results from the presence in one case of inorganic matter combined with silver, and in the other case its absence. When a plate is coated with collodion containing cadmium bromide, zinc bromide, or potassium bromide, and placed in astrong silver nitrate: bath, and developed with either acid developer or with ferrous citro- oxalate, we get curves similar to figs. 31 and 32. The same figures also represent the action of the spectrum on collodio-bromide emul- sions transmitting orange light by any kind of development. This applies equally whether the plate be exposed wet or dry, or whether exposed in the presence of silver nitrate or other inorganic sensitisers. Figs. 29 and 30 show the results obtained when using gelatine bromide plates with the silver bromide in the grey molecular state, whether exposed with an inorganic sensitiser, or without, and whether developed with an acid, alkaline, or organic iron developer. Figs. 33 and 34 represent the action on the blue-green molecular form of silver bromide in collodion, when developed and exposed under similar circumstances to the preceding case. It will be remarked that the direct visible action of the spectrum and the developed image coincide. The effect of impurity in the bromide is not so marked as it is in the iodide. The presence of iodide except in minute quantities is rare; the haloid most frequently present as an impurity being the chloride. When the spectrum on the chloride is considered, it will be seen that such an impurity is hardly possible to be detected, as the spectra impressed on it are somewhat similar in general character to those: on the bromide. Silver Chloride. Paper was impregnated with a 10 per cent. solution of sodium chloride and sensitised on a 10 per cent. solution of silver nitrate.. Paper thus prepared was exposed to the spectrum in a damp state, and also in a dry state, and the visible impression recorded. Fig. 35. shows the action. When the paper was exposed for twenty seconds to: diffused light a different curve as shown in fig. 36 was found; an approach to the same curve being also shown with very prolonged exposure without the preliminary action of light. This is probably due to the action of the diffused light in the prism.* * J have not taken into consideration the spectrum impressed on silver chloride: 176 Capt. Abney. On the Effect of the [ Dec. 15, Similar paper was washed, some was used in this state and other was afterwards treated with a solution of sodium chloride and again washed, leaving thus only a trace of an organic salt of silver in the fibre. The action of the spectrum on the simply washed paper is shown in fig. 37. With a short preliminary exposure, traces of an impression between F and C were obtained, tending to show that the preliminary action in fig. 36 was effective on the chloride besides on the organic compound of silver. Fig. 38 gives the action of the spectrum in the chloride which had all traces of silver nitrate removed by the wash of sodium chloride. To obtain an emulsion of silver chloride in collodion, 20 grains of calcium chloride were dissolved in 1 oz. of collodion, and 1 gr. more, or | gr. less, according as excess or defect of silver nitrate was re- quired, than the equivalent of silver nitrate dissolved in another ounce of collodion; the former solution was poured in the later, shaking at intervals, till a perfect emulsion was obtained. In some cases the emulsion was washed in the ordinary way known to photographers, and in others used when made as above, and the films washed or exposed in their natural state. In no case did any difference in the resulting impression of the spectrum appear. I may also state that other chlorides were tried, and there is no apparent difference from those obtained where sodium chloride was employed. Fig. 38 also gives the action of the spectrum on such emulsion, there being no. apparent difference between the washed emulsion or the emulsion exposed with an excess of silver nitrate, or with an excess of the soluble chloride, unless it be one of general sensitiveness. In other words, the spectrum seemed to act on the silver chloride in one and the same manner. Fig. 39 shows the printing action on the chloride when enveloped in gelatine. The emulsion was formed in the usual manner habitual amongst photographers, each ounce of emulsion con- taining about 25 grs, of converted silver nitrate. Fig. 39 has refer- ence to this emulsion after it was heated to its boiling point for half an hour, and when treated with ammonia; when used unboiled it took ‘an impression similar to fig. 38. When these same preparations of the chloride in gelatine are exposed for a short time to the spectrum and developed with ferrous -citro-oxalate developer, or with gallic acid and silver, we get figs. 42, 43, 44 and 45, the first two expressing the result of the unboiled emulsion which transmits yellow-orange light, and the two latter numbers that on the boiled emulsion which transmits a blue-grey light. visibly darkened by the light. This, as is well known, is impressed throughout the spectrum, and takes the approximate colour of the spectrum. ‘This is true whatever vehicle is used to hold the silver chloride, and also whether exposed in the presence -of an excess of silver nitrate or other sensitiser, and also when organic compounds of silver are mixed with it. | 1881.] Spectrum on the Haloid Salts of Silver, &e. BAcCl+AgNO, onpaper.... Print. B AgcCl1+AgNO, on paper, slight Print. ® preliminary exposure. # AgCl on paper washed from Print. excess of AgNO,. AgCl on paper washed and Print. treated with NaCl and washed again, also collodio chloride of silver, also yellow 4 form of AgCl in gelatine. Grey form of AgCl in gela- Print. tine. met A&C] in collodionin presence Developed H of excess of AgNO, or NaCl (dong developed; ferrous ciirate, exposure). # or acid development. y Ditto ditto = «. (short exposure). m Yellow form of AgCl in gela- Developed tine acid or ferrous citro- (long oxalate development. exposure). may 1itto ditto ae 2) (Short exposure). may Grey form of AgClin gelatine, Developed acid, or ferrous citro-oxalate dong development. exposure). ND I eee M Ditto ditto ie ... (short exposure). B® AgCl in collodion given a Developed. short preliminary exposure, acid, or ferrous citrc-oxalate development. Agi+AgBr+AgNO,0n paper, Print. moist. AgI+AgBr, washed from Print. AgNO,. a m Ditto, ditto. developed ferrous Developed. f «© citro-oxalate. : AgI + AgBr + AgNO,, wet Developed. plate, developed acid, or alkaline developer. IR eas ae Ee © Agi+AgBr in gelatine, deve- Developed. loped ferrous oxalate. mn AgBr+AglI in collodion, acid Developed } or alkaline developer. (long exposure). Load Set a oe eee 4 Ditto ditto ee ... Developed (short exposure). AgI+AgBr, on paper soo LEU 178 Capt. Abney. On the Effect of the [Dec. 15, The first numbers of these pairs of figures show the result of exposures ten times longer than the exposures shown by the second numbers of the pairs. Silver chloride in collodion by whatever means prepared, and whether exposed with an excess of silver nitrate, or an excess of soluble chloride, gave figs. 40 and 41, the former being the result of exposure ten times longer than that shown by the latter. The mode of development had no effect on the spectrum developed. The washed paper gave on development the same result as that shown for the direct action of light, viz. fig. 37. The mode of development had no effect on the result. The washed paper subsequently treated with a solution of sodium chloride and again washed, when exposed to the spectrum gave on development with either gallic acid, and silver nitrate, or with ferrous citro-oxalate, the same figure as that obtained by the direct action of light, viz., fig. 38. When a brief preliminary exposure to white light was given to either the paper or the different emulsions, fig. 46 was obtained on development. On looking at figs. 35 to 46 it will be seen that in- variably the maximum intensity isreached between H andh. Accord- ing to many authors the maximum is near G, whilst, according to others, it is in the ultra-violet. I have carried out about 200 experiments on the chloride with sunlight and with the electric hight, and in no case have I found it possible to alter the maximum. Of course if candle or gas light be used as a source the maximum will be about G, since the ultra-violet rays are almost absent with these. The idea suggests itself that the prismatic arrangements employed may be at fault; in some cases where the most definite results have been registered, a direct vision spectroscope has been utilised. I need hardly say that such an arrangement, from the very nature of the apparatus, is unsuited for photo-spectroscopy. Such a spectroscope transmits very few rays beyond H, and at H their intensity is much diminished. In order to settle the matter to my own satisfaction, I used a diffraction grating with the same results as those shown in the fioures under consideration. In a paper read before the British Association in August last, I pointed out the great need of caution in measuring daylight intensity by the chloride, and my subsequent examination of the subject has more than ever confirmed me in my opinion therein given. Methods of obtaining Mixtures of Silver Iodide and Bromide, Silver Iodide and Chloride, Sc. To test mixtures of the iodide and bromide, paper was prepared by immersing it in a solution of potassium iodide and potassium bromide, the proportion of each being so arranged that there should 1881. ] Spectrum on the Haloid Salts of Silver, &c. 179 be definite proportions between each, supposing that each salt was entirely decomposed by the silver nitrate. Unfortunately this is never absolutely the case, and hence the results obtained with the paper must be received with some caution. Chemists know that silver bromide or silver chloride cannot exist in the presence of a soluble iodide, nor can silver chloride in presence of a soluble bromide. Hence when we have an iodide and bromide impregnating paper, the silver iodide will first be formed, and then the bromide; or, again, with iodide and chloride, the silver iodide will first be formed and then the chloride; and, finally, with bromide and chloride, the bromide will first be formed and then the chloride. It was necessary to make these remarks, as a right conception of the results might not be taken on casually looking at ian. The same remarks apply with equal force when a sensitive film of the double salts is prepared by the ordinary silver bath when very short immersion is given to the plate. The only true way of obtaining definite results seems to be by means of separate emulsions, in which a definite amount of soluble chloride, bromide, or iodide is fully con- verted into silver chloride, bromide, or iodide, and then to mix these emulsions, after proper washing, in the required proportions. It was in this manner that the emulsions which will be discussed presently were prepared. I would here call attention to a somewhat remarkable behaviour of silver iodide. It is well known that if silver iodide be prepared with an excess of soluble iodide, it is totally insensitive to ight. Thus if we prepare (say) an emulsion in collodion with an excess of iodide, and wash it thoroughly in the usual manner, and after redis- solving the pellicle resulting from the washing operations, expose it in the camera, no amount of development will bring out an image. If, however, to such an emulsion but a drop of a bromide or chloride emulsion be added sensitiveness will appear. This seems to be due to the last trace of soluble iodide being converted into silver iodide. Mixtures of Silver Iodide and Bromide. fiqual Equivalent Proportions of Iodide and Bromide.—Paper was soaked in a solution of equivalent proportions of soluble iodides and bromides, and, after drying, was sensitised on a 10 per cent. solution of silver nitrate for such a time that the back of the paper became thoroughly damp. ‘The silver nitrate solution was acidified in order to prevent the formation of any sub-salts. A strip of such paper was exposed to the spectrum whilst moist, and the printing action noted. The result is given in fig. 47.. Similar paper was washed and treated with potassium nitrite, and exposed whilst moist; the effect of the action of the spectrum is seen in the same figure. 180 Capt. Abney. On the Effect of the [Deca Paper was next washed, and portions were treated with a solution of potassium bromide, and again washed. Strips of these two speci- mens were dried and exposed to the spectrum, and in both cases the printing action is seen in fig. 48. Similar papers, in a moist state, were also exposed without any deviation of the result. Again, paper which had been prepared as above was allowed to dry with the excess of silver nitrate on it, and exposed, and fig. 48 again approximately resulted ; as also it did when the washed paper treated with potassium nitrite was dried. The difference between curves 47 and 48 is very remarkable, and at first sight might not seem to admit of explanation. A study of the experiments described, however, affords a clue to the apparent incon- eruity of the results. According to text-books on chemistry, bromine will displace iodine in combination, whilst iodide displaces bromide. Later researches seem to modify the first statement toa certain extent. Bromine will only displace a definite proportion of iodine when it is in excess ; but for our purpose we may take the text-book statement as practically correct. When the paper was exposed wet with either silver nitrate or potassium nitrite (I may remark that other halogen absorbents gave the same result) the iodine and bromine liberated by the action of light would be at once absorbed by them; in the one case silver iodide (or bromide) and silver iodate (or bromate) being formed, and in the other potassium iodide (or bromide) ; so that each of the two kinds of sensitive salt would have its full action. When the paper was washed and exposed in a dry state the result would be different, and the question would arise, what would become of the iodine and bromine liberated by light ? If silver iodide be exposed to hght and treated Witla a trace of bromine, the sub-iodide combines ce the bromine, and all trace of the action of light is destroyed. Thus when the mixture of iodide and bromide is exposed to light, both iodine and bromine being liberated, the bromine will at once combine with the sub-iodide and destroy it. Thus, Ao I+ Br=Ag,IBr, the only factor remaining being the sub-bromide, which is develop- able. Now it may be said that the iodine liberated should also destroy the sub-salts; but it is a matter of fact that, in the presence of light, it has no power of destroying the sub-iodide, since it is immediately again shaken off from the molecule.* Iodine can destroy the sub- bromide molecule, and form a new saturated molecule; thus, Ag, Br+ Il=Ag,BrI. * [At the same time it must be noted that the iodide is much less sensitive of light when no absorbent of iodine is present. This is fully accounted for by the immediate recombination of, at all events, a portion of the lodine liberated with the sub-iodide molecule.—Dee. 19. | 1881. | Spectrum.on the Haloid Salts of Silver, &c. 181 Whether the two molecules Ag,BrI and Ag,IBr have the same value is a moot point, but the evidence tends to show that such is the case. If the equivalents of bromide and iodide were equal, that is, if the bromide and iodide of silver were equally distributed, supposing both the above actions took place, the locality of the spectrum in which the iodide and bromide are equally sensitive should show an almost entire destruction of a developable image, and also of a printed image. This locality is doubtless about G, and when we come to analyse the curve in fig. 48 we see that there is very small effect about G, whilst there is an increased effect between Gand F. Now, to test the matter further, paper prepared with washed silver bromide was exposed to light till it darkened thoroughly, and such paper was treated with a very dilute solution of iodine, and then exposed in the spectrum, with the result given in fig. %4, in which it will be seen that the new molecule is more sensitive to the green between G and F than above G; in fact, we have very little action comparatively at G and above it. In this case we have then a paper prepared in which there is an absolute imitation of the action that takes place in the mixed iodide and bromide. It cannot be said that by this treatment we have Ag I,+Ag,Br., since the molecule formed by hght is Ag,Br, and the addition of the iodine is simply to form Ag,BrlI, which is very different from a simple mixture. This experiment then “seems to show that this new molecule is more sensitive to the blue-green than it is to the violet. The point then comes as to how, when the original paper is exposed to the spectrum, we have not only a fall of sensitiveness at G and beyond it, but also a greater sensitiveness in the green. Now, silver iodide, as has already been shown, is not in the least sensitive to beyond a very small region below G; therefore, in the green the only component of the mixture of bromide and iodide that can be acted upon is the bromide. As we see when bromide is acted upon one atom of bromine is liberated from the molecule; thus, Ag, Br,=Ag,Br+ Br. The liberated atom of bromine immediately attacks the molecule of iodide in its immediate neighbourhood and forms a new bromo-iodide molecule liberating iodine. Thus Br+Ag,I,=Ag,IBr+T, and the iodine either escapes or else forms the molecule Ag, BrI; thus , Ag, Br+I=Ag,Brl. Here then it is probable that we have a new saturated molecule formed by the action of light, which on formation is susceptible of being acted on by light in its turn. Whether iodine or bromine is i 182 Capt. Abney. On the Lifect of the [Dec. 15, liberated from this new molecule I am not at present prepared to state, but it is my belief that it is the iodine, since density in develop- ment by the alkaline method is readily obtained when experimenting with it. To sum up, the difference in shape between curves 47 and 48 seems to depend on the destruction of the sub-iodide when formed, and its conversion into a new molecule, which is sensitive to the blue-green, the same new molecule being formed by the liberation of the bromine from the molecule of silver bromide when the sub-bromide is formed. In the case of the paper which is dried in the presence of silver nitrate and potassium nitrite the same result occurs. Bromine and iodine attack these salts when in a crystalline state with difficulty, and hence will in preference form the new molecules as before. Fig. 49 shows the curve of washed paper when developed with ferrous citro-oxalate, and nearly the same result is seen when the development proceeds by acid development, the difference being that the dip in the curve between h and G is less pronounced. To illustrate this further, in Fig. 50 we have the case of a collodion film containing equal parts of silver iodide and silver bromide and an excess of silver nitrate, the latter salt absorbing both the iodine and bromine libe- rated. In fig. 52 we have the results obtained from the same film, but thoroughly washed from all excess of silver nitrate. Whether the plates be developed by acid, alkaline, or an organic ferrous salt, the curves remain in all essential particulars the same. In fig. 51 we have the curve resulting from the same mixture (equal equivalent propor- tions) held in gelatine when developed by ferrous oxalate or alkaline developer. At first sight it might be said that this action is really due to the “reversing action” of light, of which I have treated in the ‘‘ Proceedings of the Royai Society,” in 1878, and in the “ Philo- sophical Magazine’’ for 1880. That this is not the case is shown by fig. 53, in which the exposure was exceedingly short; in fact, when very quick exposure was given the curve started at h and reached a maximum as shown in fig. 53. These results are exceedingly inte- resting and important. There is a figure showing something some- what Suitllan | in Vogel’s “ Lehrbuch der Photographie,” Berlin, 1878, but there is no Salbnoion of the cause, nor has it been noticed by any other observer, as far as I am aware. Three Parts of Iodide to One of Bromide—When we take three equivalents of silver iodide to one of bromide the curves are somewhat modified. When washed paper prepared with the above proportions is allowed to print in the spectrum, we have the curve shown in fig. 54. When exposed damp in the presence of silver nitrate or other imor- ganic sensitiser, we have almost a facsimile of the curve in fig. 47. Washed paper developed with acid developer shows that the propor- tion of iodide is so large in comparison to the bromide that the sub- nS81.] Spectrum on the Haloid Salts of Silver, $c. 183 iodide is not all destroyed, and we get the maximum corresponding with the maximum of pure silver iodide, fig. 55. The same paper developed with ferrous citrate shows a slight dip near G, fig. 56. The difference in 55 and 56 is seemingly due to the fact that silver iodide has more attractive power for precipitating metallic silver than has the bromide (a fact which is well known) and that the bromide is more amenable to reduction than is the iodide. Figs. 57 and 58 are well worthy of attention. They are the results of the exposure of the same plate for different lengths of time to the spectrum. It was prepared in the silver nitrate bath and exposed in the presence of free silver nitrate. Taking fig. 57 alone, it might be supposed that we had a similar case to that which we have recently considered, since we find an extraordinarily (apparent) greater sensi- tiveness in the green than in the violet, and yet we have the image formed in the presence of an excess of silver nitrate, which would be against the theory I have promulgated. Tig. 58, however, clears up the discrepancy: the maximum is found to be at G, and in this case the dip in the curve of fig. 57 is caused by the reversing action alluded to. Fig. 59 gives the curve obtained by the above mixture of three parts of iodide to one of bromide; when emulsified in gelatine the bottom curve shows a short exposure. One Part of Iodide and Three of Bromide—We now come to a mix- ture of one part of silver iodide to three of bromide. I have not described the printed spectra since they correspond nearly with figs. A7 and 48, If we compare the curves in figs. 60 and 57 we see a strange simi- larity between them, but if we take into consideration fig. 61, which is that due to a short exposure on the same plate, we shall at once see that the dips about G are due to two different causes; the dip in fi. 61 is caused by the formation of the new molecule. Figs. 60 and 61. are also the curves shown by paper prepared with the above equi- valents of iodide and bromide, and also of the same in collodion when developed by an organic ferrous salt. When developed by acid deve- lopment, the curve in the more refrangible region is a little more pronounced in character. _ Figs. 62 and 63 show the same equivalents emulsified in gelatine and developed by ferrous oxalate. The different equivalent proportions of bromide to iodide, it will be noticed, show themselves in the curves more particularly when a com- parison is made between figs. 51, 59, and 62. Mixture of Iodide and Chloride. Three Hquivalents of Iodide to One of Chloride—When paper is prepared with three equivalents of silver iodide to one of Bevo. XXXII. O Capt. Abney. On the Effect of the [ Dec. 15, m@3AgIl+AgBr on paper deve- Developed. | loped gallic acid. Ditto, developed ferrous Developed. citrate. 3AgI+AgBr+AgNO, collo- Developed dion, wet plate, acid or (long alkaline developer. exposure). Ditto ditto oye we (short exposure). Developed 3AgI+AgBr in gelatine, alka- (long and line, or ferrous oxalate short developer. exposure shown). AgI+3AgBr on paper or in Developed collodion, ferrous citro- (long oxalate developer. exposure). | Ditto ditto ava) od tee yh (a (SBOrk exposure). @ Acgl+3AgRr in gelatine, fer- Developed rous oxalate developer. (ong exposure). Ditto ditto 33 Cee (short exposure). 3AgIl + AgC]l + AgNO, on Print. paper, or ditto washed, both dry. 3AgIl+AgC1l4+AgNO, wet, or Print. 3AgIl+AgCl1+KNO, wet. 3AgI + AgCl + AgNO,, or Developed. — 3AgI + AgCl+ KNO, on paper, developed with gallic acid or ferrous citro-oxalate. Washed 3AgI+AgClon paper, Developed. ferrous citro-oxalate deve- loper. 3Agl+AgCl in gelatine, de- Developed. veloped ferrous oxalate. AgI+AgCl in gelatine, deve- Developed. loped ferrous oxalate. AgI+8AgCl paper, washed. Print. AgI+3AgCl+AgNoO, wet. Print. AgI+3AgCl in gelatine, or on Developed. paper, developed with fer- rous citro-oxalate or acid developer. Agl + 3AgCl + AgNO,, acid Developed. developer. AgBr exposed to light treated Print and with I, exposed to spectrum. also deve- loped. 1881. ] Spectrum on the Haloid Salts of Silver, &c. 185 chloride and washed and dried, or if exposed in the presence of dried silver nitrate or dried potassium nitrite, we have the curve shown in fig. 64. Tf, on the other hand, we have the same paper exposed moist, with silver nitrate or potassium nitrite we have the curve shown in fig. 65. The reasoning applied to the mixture of iodide and bromide applies with equal force here, the results being modified for the shift of maximum of the chloride which lies about > Hh. In fig. 64 the most refrangible part of the spectrum as far as G is ruddy, between G and F a pink colour, and beyond that grey. This difference in colour indicates (as it does in all other photo- graphed spectra where different colours are impressed or developed) a difference of compound acted upon. According to our theory the molecule acted on beyond G in the violet and ultra-violet would be Ag,I,+AgICl, and between G and H Ag,IC]+Ag,Cl, alone. The grey here is probably due to the organic silver compound formed in the paper. Fig. 66 shows the same equivalents if contained in paper or collodion, and when exposed to light in the presence of moist silver nitrate or other inorganic sensitiser and developed by acid or ferrous citro-oxalate developer, the slight modification due to the former developer noted above still holding good. Fig. 67 shows the same paper or collodion emulsion washed and developed with ferrous citro-oxalate. Fig. 68 shows the same when emulsified in gelatine and developed with the same ferrous developer. There is a difference in the curves obtained with collodion and gelatine, but not more than is explainable by the fact that the former is essentially porous and the latter almost continuous. One Hqmvalent of Iodide to Three of Chloride-—When three equiva- lents of silver chloride are taken with one of iodide, we have, on printing a washed paper, the curve shown in fig. 70; exposing the same paper moist in the presence of silver nitrate we have fig. 71; the reasoning given when the mixture of bromide and iodide was under consideration holds good. Figs. 72 and 73 show the same equivalents of sensitive salts held in paper, the former showing the action of development on washed salts and the latter on the same exposed in the presence of moist silver nitrate. Fig. 69 shows the effect of the spectrum on equal proportions of the iodide and chloride when emulsified in gelatine. Paper and also collodion films containing silver chloride were blackened in the light and treated with a solution of iodine till the darkening was obliterated, washed, and then exposed, with or without sensitisers; we had nearly the same results on printing and on development as shown in fig. 74, hence, it was thought useless to repeat the curve there shown. (The same applies to darkened bromide treated with iodine, exposed to the spectrum and developed.) 02 186 Effect of Spectrum on Haloid Salts of Silver. [Dec. 15,. This appears to be a confirmation of the view already propounded regarding the formation of a new molecule, in the case of the chloride and iodide the new molecule taking the form of Ag.CH, as already indicated. From these results we may observe that to cbtain a compound sensitive to the green a mixture of iodide and bromide, or iodide and chloride, should be employed, the former in preference to the latter, since it is more sensitive. The same sensitiveness to daylight with the former in gelatine plates can be obtained as when using pure bromide alone, the sensitiveness being preserved by a shift of the maximum to the green. Mixtures of Silver Chloride and Bromide. There is nothing special calling for remark in a mixture of these two sensitive salts. The printed spectrum and the developed spec- trum seem to be a combination of the spectra impressed on each individually, a sight prolongation towards the least refrangible end taking place. Mizture of Silver Iodide, Bromide, and Chloride. When these three salts are combined together we have spectra which are very similar to the spectra produced on iodide and chloride, or iodide and bromide, with a prolongation towards the red. Concluding Remarks. In a paper read, in 1880, before the Photographic Society of Great Britain, I recommended the addition of a small quantity of iodide to the bromide used in the preparation of gelatine emulsion. On carefully examining spectra photographed on such plates (having =; part of iodide to 4+ of bromide) I find traces of the loss of sensitiveness about G. I stated also that addition of iodide diminished the sensitiveness of the bromide to the red rays; an examination of curves given for the mixtures of bromide and iodide of silver bears out my statement. It will be noticed that I have not touched upon organic sensitisers of the haloids, prepared with an excess of silver and then washed, and such sensitiser applied. I have only treated of the haloids themselves, endeavouring to eliminate every extraneous effect which would modify the action of the spectrum. I purpose in a subsequent communication to enter into this part of the subject. 1881.] On a New Electrical Storage Battery. 187 VI. “On a New Electrical Storage Battery.” By Henry SUTTON (Ballarat, Victoria). Communicated by ‘THE PRESIDENT. Received December 10, 1881. The great utility of some thoroughly practical method of con- serving electric force has caused a great deal of attention to be applied to the subject; no system of electric supply can be con- sidered as perfect until some means is used to so store the force generated that it may be drawn off equally and regularly, and this whether the generator be on or off. If we take, as an example of electric supply, the present systems of electric lighting, it is at once seen, should an accident or stoppage take place in the machinery generating the current, the whole of the apparatus such as lamps or motor-machines are influenced; should there be a reservoir of elec- tricity between the generator and the apparatus of whatever sort for utilising the force this inconvenience would not occur. Ail the present systems of storing electricity depend on certain chemical changes produced by electrolysis. I have gone through a long series of experiments on storing elec- tricity and made many forms of cells, one being a porous pot con- taining dilute hydric sulphate and a sheet of lead, in an outer vessel containing a sheet of lead in solution of acetate of lead, the plate in the porous pot being made the positive electrode; this cell had the power of storing electricity, by peroxidising the positive electrode, and depositing from the acetate of lead solution metallic lead on the negative electrode, the hydrogen having combined to form acetic acid. On discharging the peroxide is reduced, and the oxide formed during discharge on the other plate dissolves in the acetic acid, forming the original solution of acetate of lead; by this means I eliminated the injurious effects of the hydrogen on charging. During my experiments I found that red oxide of lead is a very bad conductor of electricity, and the peroxide a good conductor. I also discovered that by amalgamating lead plates with mercury a marked increase was immediately manifest in polarisation effects, the plates becoming more uniformly and rapidly peroxidised when used as positive electrodes, and local action entirely disappearing. These mercury amalgamated plates at once gave me an advance of other cells. I used them in many ways, constructing cells in which the positive plate was amalgamated, and the negative coated with red oxide, or with peroxide, produced by treating red oxide with dilute hydric nitrate till the brown precipitate of peroxide fell, the pre- cipitate being washed and painted on the electrode. I also amal- gamated the negative electrode simply. I found that in every way positive electrodes amalgamated produced the best results. I also 188 Mr. H. Sutton. | Dec. 15, made cells in which either peroxide or red oxide was formed into a porous conglomerate, using the conglomerates as electrodes, immersed in dilute hydric sulphate. I constructed cells with parallel plates, red oxide or peroxide being filled in between the plates; in this experi- ment red oxide is useless and peroxide efficient. In all these experi- ments I succeeded in storing electricity to different extents. Having thoroughly satisfied myself that positive electrodes amal- gamated with mercury were the best, I investigated the behaviour of various forms of negative electrode, having in view the conservation of the hydrogen; this I thought to do by occluding the hydrogen in suitable electrodes, as spongy platinum or metallic palladium ; but as both these methods would be useless owing to expense I did not even experiment on them. I further thought of having negative electrodes, whose oxides. should be soluble in the solution, and which could be redeposited from the solution, or of having metallic solutions from which metal could be deposited, the resulting solution being such that should, on the oxidation of the deposited metal, combine with the oxide and again form the original solution. I thought that success in this manner would result in a powerful and constant source of stored energy, the cell would not polarise itself during discharge, as is the case in both Planté and Faure cells; in these cells the peroxide formed by the discharge produces a contrary electromotive force. Experimenting from this train of thought, the results I have obtained are such as to have an important practical bearing on the future of electric work. The experiments comprised amalgamated lead as a positive elec- trode with negative electrodes composed of either zinc, iron, or copper, in each case the solution between the electrodes being a salt of the metal composing the negative electrode. With zine, sulphate of zinc was the solution; with iron, sulphate of iron; and with copper, sulphate of copper. In all these cases the results were not only far more powerful than with any form of cell I had pre- viously devised, but also very constant, the polarisation lasting many times longer than in any other form of cell. The cell with zinc negative electrode I discarded, owing to the necessity there would be to keep the zine plate amalgamated to prevent local action; the iron negative electrode was set aside owing to the iron oxidising when the cell was not in use. The cell having a negative electrode of copper, a positive electrode of lead amalgamated with mercury and a solution of cupric sulphate, I have adopted as a thoroughly economical, lasting,. and practical form of storage reservoir. The chemical changes in this cell are exceedingly interesting and beautiful, the cell being com- posed of a sheet of lead cleaned with dilute sulphuric acid and amal- 1881.] On a New Electrical Storage Battery. 189 gamated thoroughly with mercury, and a sheet of thin copper a little shorter; the two sheets are perforated with a number of holes and then rolled in a spiral, separated by rubber bands cut every five inches, the holes in plates and cuts in rubber bands being to allow free circulation of the solution (the short plate being uppermost before rolling). This combination is immersed in a solution of cupric sulphate, and the amalgamated lead plate made the positive electrode of a suitable source of electricity, the chemical action being that the oxygen of the decomposed solution combines with the lead, forming a perfectly even coating of the insoluble peroxide, the hydrogen re- placing the copper of the solution, and the copper being deposited in the metallic state on the negative electrode. As the decomposition of the cupric sulphate proceeds the solution gradually loses its azure blue colour, becoming more acid, and finally when the whole of the copper is deposited, we have the solution colourless and transformed into hydric sulphate and water, the positive electrode peroxidised and copper deposited on the negative electrode. During discharge the peroxide is reduced and the copper element oxidised, the oxide combining with the acid and forming cupric sulphate, the solution returning to its original colour. This change of colour forms a beautiful means of tellmg when the cell is charged; it is a veritable charging gauge. The power of this cell is very great and very constant, it can be made to last for hours, the time being dependent on the quantity of cupric sulphate decomposed. I have, by the decomposition and recomposition of one pint of cupric sulphate, obtained over two hours’ effective work in heating to a red heat one inch of No. 28 iron wire, the cell measuring internally 4, inches deep and 4 inches diameter. I constructed cells with free crystals of cupric sulphate suspended in the solution, and found that the presence of free crystals prevented the oxidation of the amalgamated lead electrode, it being essential that the solution become slightly acid before the peroxide will form. The cell during charging gives out a peculiar rattling noise, which I consider due to the deposition of copper on the negative electrode altering the form of the spiral. A practical form of cell for storing purposes ought to be made, by fixing a series of amalgamated lead piates in a box in grooves, as in Cruikshank’s trough battery, filling the interval between the plates with solution of cupric sulphate, and passing a current through of sufficient tension to overcome the contrary electromotive force of the series, the positive sides of the plates being peroxidised and copper deposited on the negative sides. I have two boxes on this plan, each containing twenty-five plates, the total being equivalent to fifty cells. By this means batteries of great tension can be charged from thirty Bunsens. A number of twenty-five plate boxes can be coupled for 190 Mr. W. Heape. On the Germinal Layers [Dec. 22, quantity in charging, and for tension during discharge. Twenty such boxes, one foot square, internal measurement, will give in series a battery of 500 pairs of one foot square plates. It will be seen from the foregoing that this method of conserving energy has a wide field before it, and as it will benefit fellow-workers in science, placing in their hands a means of experimenting with powerful electric currents, I give it without reservation, freely and untrammelled by patent rights, for their use. December 22, 1881. THE PRESIDENT in the Chair. The Right Hon. Sir William George Granville Venables Vernon Harcourt, Knt., was admitted into the Society. The Presents received were laid on the table, and thanks ordered for them. The following Papers were read :— I. “On the Germinal Layers and Early Development of the Mole.” By WattTerR HEAPE. Communicated by F. M. BALFourR, F.R.S. Recerved November 30, 1881. The following is a note on some investigations which I have been carrying on by the kindness and with the help of Mr. Balfour, in the Morphological Laboratory, Cambridge, upon the origin and formation of the germinal layers in mammals, more especially in the mole (Talpa Huropea). I hope shortly to be able to givea more complete account. In the communication the following subjects are dealt with :— (1.) The origin of the epiblast. (2.) The mode of development of the mesoblast. (3.) The structure of the neurentéric canal. (4.) The relations of the mesoblast and the hypoblast to the noto- chord. Recent investigations have left the earlier phases of mammalian development in some confusion, it may therefore be advisable briefly to mention the more important views which are entertained on this subject. Professor Edward van Beneden, in a paper entitled ‘“ La formation des fenillets chez de Lapin” (‘“‘ Archives de Biologie,” vol. i, Part 1, 1881. | and Karly Development of the Mole. nL 1880), gives an account of the segmentation of the ovum of that animal, and states that during segmentation a differentiation of the segmentation spheres into two layers is established, the ‘one of which grows over aud encloses the other, giving rise in this manner to what Van Beneden calls a metagastrula. The outer of these two layers he terms ectoderm and the inner entoderm, names which seem to me, for reasons which will appear in the sequel, to be misleading, and for which I propose to substitute the terms outer and inner layers respectively. Subsequently, according to Van Beneden, a cavity, the blastodermic cavity, is developed between the outer and inner layers of cells; the cells of the former layer become flattened and multiply, and form the wall of the so-called blastodermic vesicle; at the same time the blasto- dermic cavity is enlarged, while the inner layer remains as a rounded mass of cells attached to the wall of the vesicle over a small area known as the embryonic area. Van Beneden considers that the outer layer of cells forms the permanent epiblast, both of the embryonic area and of the blastodermic vesicle, while the inner mass of cells breaks up into two layers, a lower single layer of flattened cells, the hypoblast, and a layer of cells which he calls the mesoblast, lying between the hypo- blast and the epiblast of the embryonic area. _ Professor Kolliker, on the other hand, writing in the “ Zoologischer | Anzeiger” (Nos. 61 and 62, vol. in, 1880), ‘“‘ Die Entwicklung der Keimblatter des Kaninchens,” does not dispute the presence of Van Beneden’s epiblast, hypoblast, and mesoblast, in the stage of develop- ment described above, but states his agreement with an earlier view of Rauber, that in the region of the embryo the outer of these layers disappears, while the whole of the middle layer becomes converted into the epiblast of the embryonic area; the epiblast of the remainder of the vesicle, however, he considers is formed from part of the original outer layer of cells. The mesoblast owes its origin, in his opinion, wholiy to a budding from the epiblast of the primitive streak. Professor Lieberkthn published in Marburg, in 1879, in a paper “Ueber die Keimblatter der Siugethiere,” the results of his researches upon the dog and mole, in which he states that the epiblast of the em- bryonic area is derived from the greater part of the primitive inner mass of cells (that portion in fact forming Van Beneden’s mesoblast), together with the part of the original outer layer of cells which over- lays the mner mass ; the hypoblast he derives from the inner mass of cells, while the mesoblast he believes to be formed from both epiblast and hypoblast, in the region of the primitive streak. I myself have been fortunate enough to secure a fairly complete series of mole embryos ranging from an early appearance of the blasto- dermic cavity until the formation of the medullary groove; an exami- 192 Mr. W. Heape. On the Germinal Layers [Dec. 22, nation of which leads me, in the main, to agree with Lieberkiihn’s account of the development of the embryonic layers of that animal. I have not been able to follow completely the course of segmenta- tion, nor have I been able to trace a differentiation of the seements into two layers, an outer and an inner, though there appears to be no doubt, on account of the arrangement of the spheres in a somewhat later stage, that Van Beneden’s description of a fully segmented ovum is substantially correct. The earliest specimen of an ovum in my possession after the com- pletion of segmentation is similar to that figured in Van Beneden’s paper (loc. cit.), Plate IV, fig. 6, III, and in Lieberkiihn’s paper (loc. cit.), fig. 1. The ovum consists of an outer layer and an inner mass of cells, between and partly separating which is a cavity. The outer layer has the form of a sphere of somewhat flattened cells, while the inner mass is composed of irregularly polygonal cells; these two are attached together for a small area, elsewhere they are separated by a cavity, the blastodermic cavity, which is seen in optical section as a crescent- shaped space partially surrounding the inner mass of cells. The diameter of this ovum measures ‘11 millim., and that of the mner mass of cells ‘06 millim. A thick zona invests the ovum. Upon the formation of the blastodermic cavity, the ovum may be called the blastodermic vesicle. The vesicle becomes enlarged, and I am inclined to believe, that during the enlargement, the cells of the mner mass assist in the formation of the outer wall of the vesicle, since in various vesicles of about °2, °25, °3, °38 millim. diameter, the diameter of the inner mass, which is of an approximately spherical shape, is less, being respec- tively -04, 04, ‘04, ‘05 millim., than in the youngest vesicle, mea- suring as stated above, ‘11 millim. in which the inner mass is. “06 millim. diameter. Sections through a vesicle measuring ‘25 millim. diameter (the inner mass measuring about ‘04 millim.) show the outer layer to be composed of greatly flattened cells closely applied to the zona, which is now much thinner, owing to the expansion of the vesicle, while the inner mass in the form of a solid mass of irregularly rounded cells is attached to the outer layer for a small circular region, which I shall speak of as the embryonic area. As the vesicle enlarges, the inner mass of cells slightly flattens out and widens at the same time, so that the embryonic area becomes. enlarged. In a vesicle ‘44 millim. diameter, the inner mass of cells is seen to: be commencing to divide into two layers, and in a vesicle ‘57 millim. in diameter, in which the inner mass is ‘08 millim. in diameter, this division is completed, and a layer composed of a single row of 1881. ] and Karly Development of the Mole. 193: slightly flattened cells is separated off from and underlies the main portion of the inner mass of cells; this layer is the hypoblast. The main portion of the inner mass of cells is undergoing at the same time a change in structure, inasmuch as some of the polygonal or rounded cells of which it has hitherto been composed now become elongated and columnar. The hypoblast in an oval blastodermic vesicle of about ‘88 millim. by °81 millim., is still formed of shghtly flattened cells beneath the embryonic area, but it has grown and extended beyond that area, so that its outer part lies beneath and in close contact with the outer layer of the blastodermic vesicle; the cells of this portion of the hypoblast are wide and much flattened, and their nuclei stain deeply with hematoxylin. A cavity appears about this stage of development in the region of the embryonic area between the flattened outer layer and the inner mass, the cells cf the latter having now largely become columnar. In the vesicle last mentioned (‘88 millim. by ‘81 millim.), nearly the whole of the inner mass has become transformed from a rounded mass of polygonal cells into a concave plate of columnar cells, forming the floor of a cavity which is roofed over by the cells of the outer layer of the blastodermic vesicle. In this cavity a few cells are placed, which are connected with the outer layer or inner mass, or with both of these, by means of protoplasmic processes; I believe these cells to be cells of the inner mass which have not yet become columnar. Lieberkithn states that some of the cells of the inner mass grow round and above the cavity just described, which thus comes to lie within the inner mass. The specimens from which he derives his opinion however, were, I believe, preserved in Miiller’s fluid. I have myself seen a similar apparent arrangement in such preparations, which upon comparison with sections of vesicles of similar ages prepared in picric acid, appear to me to bear a different interpreta- tion, the layer of cells above the cavity being formed of flat outer layer cells with a few more or less isolated cells of the inner mass. In a vesicle of about ‘97 millim. diameter, the inner mass of cells has still the form of a concave plate composed of two or three layers of for the most part columnar cells: the flattened cells of the outer layer remain, as in the previously described specimen, closely attached to the zona, and the cells lying in the cavity are fewer, while some of them appear to have been drawn on to the concave plate and trans- formed into columnar cells. Cells in a transition stage may be seen on the surface of the plate. At a later stage the concave plate extends itself, the curvature becoming less, and eventually approaches to and finally comes into contact with the flat cells forming that portion of the wall of the vesicle which in the previously described specimens lay above the 194 Mr. W. Heape. On the Germinal Layers [Dec. 22, plate; the flattened cells of this part soon become columnar, and the fusion between them and the plate below becomes complete. Somewhat prior to this stage, the edges of the plate become con- tinuous with the outer layer of the wall of the vesicle beyond the region of the embryonic area. Thus, the greater part of the inner mass of cells, as Lieberkiithn correctly states, combines in the form of a plate of more or less columnar cells with that part of the flat outer layer of cells which immediately overlies it, to form a plate of columnar cells two and three rows deep ; this plate is the epiblast plate of the embryonic area, the remainder of the outer layer of cells forming the epiblastic wall of the blasto- dermic vesicle. The portion of the inner mass of cells which was separated off from the main mass as the hypoblast still forms only a single row of somewhat rounded cells, the central part of which underlies the embryonic area, while the peripheral part continually extends as a layer of flattened cells along the inuer aspect of the epiblastic wall of the remainder of the blastodermic vesicle. In concinding this portion of my subject I may add, in support of what I believe in harmony with Lieberkiihn to be the origin of the true epiblast of the embryonic area in the mole, that in the course of my work on this subject, carried on since the investigations of Mr. Balfour and myself, published in the second volume of Mr. Balfour’s “*Comparative Himbryology,”’ I have obtained from an embryo rabbit of six days four hours old, sections which appear to me conclusively to confirm the results at which we before arrived, namely, that the epiblast plate of the embryonic area is derived (as in the mole) con- jointly from the at first flattened cells of the primitive outer layer (called by Rauber and Kolliker “ Deckzellen,” and stated by those observers to disappear from the embryonic area), and from the larger portion of the primitive inner mass of cells (held by Van Beneden to be the true mesoblast, and stated by Kolliker alone to form the epiblast plate). In the sections of this embryo the cells of the already described primitive outer layer are seen in a transition stage. being wedge-shaped and prolonged in between the cells of the inner mass. At the stage of growth now arrived at the blastodermic vesicle may be considered to consist of an embryonic and a non-embryonic portion. A surface view shows the embryonic area to be iu the form of a more or less circular opaque disk. The wall of the vesicle con- sists of a two-layered and a single-layered portion; the latter, formed of epiblast, alone comprises the portion of the wall opposite to the embryonic area, while the former, consisting of epiblast and hypoblast, forms the embryonic area and the part of the vesicle immediately adjoining it. 1881. ] and Karly Development of the Mole. 195 In the course of further growth the vesicle greatly enlarges, and the zona becomes much attenuated, affording but little support to the now also exceedingly thin and delicate wall of the vesicle ; it therefore becomes difficult to obtain specimens 1n good preservation. In the earliest specimen of this stage which I possess the embryonic area is oval, measuring °74 by 48 millim. In a surface view a dark line or band is seen to run along the centre of the hinder third of the area. This is the well known primitive streak; it is narrow an- teriorly, while posteriorly it becomes broader, and finally behind takes up nearly the whole breadth of the embryonic area; it is due to the presence of a third layer of cells, the mesoblast, between the epiblast and hypoblast. Transverse sections of this embryonic area show the major portion in front of the primitive streak to be composed (1) of a plate of epiblast formed of two or three rows of columnar cells, and (2) of asingle layer of rounded hypoblast cells somewhat flattened towards the edge of the area. Immediately in front of the primitive streak there appears, extending entirely across the area, a layer of mesoblast, which is not connected with the epiblast, but is so intimately united with the hypoblast in the middle line, that the two layers cannot there be clearly distinguished, though towards the periphery of the area they are quite distinct. A section taken through the anterior end of the primitive streak discovers a narrow band of epiblast cells in the middle line, giving rise by budding to a layer of mesoblast which extends laterally to the edge of the area, and in each section following (7.e., towards the hind end of the primitive streak) the budding epiblast appears continually as a wider band until the greater part of the whole breadth of the epiblast plate is concerned in the production of mesoblast. A pit is seen in the epiblast almost at the front end of the primitive streak, and at this point a neurenteric canal will eventually be formed; this structure, hitherto overlooked in mammalian embryos, is identical with the neurenteric canal found in other types of Vertebrata. The primitive streak grows relatively longer compared with the increase in size of the embryonic area, until in a vesicle, in which the latter measures about ‘84 by ‘71 millim., the primitive streak reaches along it fully three parts of its length. It is very narrow in front, while behind it occupies the whole breadth of the embryonic area. In sections of the region in front of the primitive streak there is present a layer of cells several rows thick immediately underlying the epiblast plate. In the seven anterior sections this layer is seen beneath the epiblast, as amass which cannot be resolved into hypoblast and mesoblast; for about three following sections, placed immediately in front of the primitive streak, the layer is clearly composed of (1) a layer of flattened hypoblast below, and (2) a layer of mesoblast above. The mesoblast in the axial line is thickened in the last two of these 196 Mr. W. Heape. On the Germinal Layers [Dec. 22, sections, and posteriorly joins the anterior wall of the neurenteric canal, while the hypoblast extends as a distinct layer below the anterior end of the primitive streak. It appears highly probable that the whole layer in the seven sections at the front end of the embryonic area, is the hypoblast originally present there engaged in the act of budding off mesoblast, as Balfour believes to be the case with regard to a similarly situated portion of the hypoblast in the chick (‘‘ Compara- tive Embryology,” vol. 11, p. 129 e¢ seq.). In the three following sections where distinct layers of mesoblast and hypoblast are found, the whole of the mesoblast, with the exception of the cells forming the central thickening in the second and third sections, has, I believe, a similar origin, and may be distinguished by the form and appearance of its cells from the mesoblast of the primitive streak. The mesoblast derived from the hypoblast may be called hypoblastic mesoblast ; it joins the mesoblast of the primitive streak as the latter grows forward, and the two become indistinguishable. The primitive streak presents in section a similar appearance to that of the embryo last described; a groove—the primitive groove—is, however, present along its upper surface. The position of the future neurenteric canal is indicated by a pit in the epiblast as in the specimen described above. At a slightly later stage the embryonic area being 1:17 by ‘81 millim., the condition of the layers is much the same. A neurenteric canal now perforates the whole thickness of the blastoderm at the front end of the primitive groove. The upper opening of this canal, which is longer than the lower opening, has the appearance of a sht with its anterior wall sloping obliquely backwards; this wall is con- tinuous with the thickening of mesoblast cells in the axial line which I described in the last stage. The first traces of the amnion are now visible, as a fold of the epiblast round the whole circumference of the embryonic area; at the posterior end the folds of the two sides meet to form a hood, covering the hinder part of the area, but anteriorly I have been unable to determine the extent of their erowth. In the surface view of an embryonic area measuring ‘97 by °79 millim. in diameter, a band of a lighter shade than the remainder is to be seen in the front part of the long axis of the area, its posterior end adjoining the anterior end of the primitive streak; the latter occupies the hinder third of the area, and where it joins the light- coloured band a pit, the upper opening of the neurenteric canal, is distinctly to be seen surrounded by a dark rim. In transverse section the light-coloured band is seen to be caused by a diminution in thickness of the epiblast plate and of the mesoblast in the middle line. The epiblast of this region is bent inwards to form a groove, the medullary groove; it is wide and shallow through- 18381.] and Early Development of the Mole. 197 out, and the cells forming it are not more than two rows deep, while the remainder of the epiblast plate, except at the extreme edge, is three cells deep. Anterior to the medullary groove a continuous layer hardly differ- entiated into mesoblast and hypoblast underlies the epiblast plate. In the region of the medullary groove an axial strip of the cells underlying the epiblast exhibits no division into hypoblast and meso- blast; this portion, though partially separated from the lateral masses of mesoblast, is still connected with them however on each side by a narrow neck of cells, and is also directly continuous laterally with the hypoblast. The lateral hypoblast is quite distinct from the super- jacent lateral masses of mesoblast. The axial strip of cells under- lying the medullary groove (thus shown to be continuous with both the mesoblast and the hypoblast) may be regarded as the commencing notochord. The neurenteric canal does not any longer perforate the blastoderm, its upper part alone remaining, which is surrounded by a thick mass of mesoblast, causing the dark rim seen in the surface view round the pit. Its anterior wall is connected with the axial mass of cells under- lying the medullary groove, while its hind wall forms the front end of the primitive streak. The surface view of a somewhat older specimen, 1°5 millims. by °81 millim. diameter, shows the medullary groove relatively much longer and more clearly defined. Anteriorly it reaches near to the edge of the embryonic area. In section it is seen to be shallow at each end, but is much deeper and narrower towards the middle of the embryonic area. Its walls, at the anterior end, are but slightly less thick than the remainder of the epiblast plate, but. in the deeper part of the groove become con- siderably thinner. Where the groove is deepest the notochord and adjacent parts form a well-marked projection into the blastodermic cavity beneath. The rudimentary notochord has now extended beyond the anterior end of the medullary groove, and its relations to the adjacent layers are, for the most part, the same as in the previously described speci- men. In front of the medullary groove it is composed of a single row of somewhat columnar cells, continuous laterally with both mesoblast and hypoblast ; below the anterior more shallow part of the medullary groove similar relations exist, towards its middle and deeper part how- ever, where the lateral mesoblast is commencing to form protovertebra, the notochordal cells, still in the form of a single row, are connected solely with the lateral plates of hypoblast, while further backwerds, where the medullary groove becomes again more shallow, the cells of the notochord become more than one row deep, and are again con- tinuous both with the lateral mesoblast and hypoblast. The notochord, 198 On the Germinal Layers, &c.. of the Mole. [Dec. 22, continually thickening towards its hinder extremity, terminates by fusing with the anterior wall of the neurenteric canal. The latter structure is now open above on the floor of the posterior end of the medullary groove, and extends dowuwards into the cells beneath, — though it no longer perforates the hypoblast, which is, however, some- what involuted, and indistinguishably fused with the mesoblast in the median line. Briefly to recapitulate, I have attempted to show :— (1.) The epiblast of the blastodermic vesicle owes its origin as well to the inner mass of segmentation spheres as to the outer layer of segments. It appears to originate in two ways: (a.) Inan early stage of development (in the mole) probably by the cells of the inner mass being directly transformed into part of the wall of the blastodermic vesicle. (b.) In a later stage (mole and rabbit) by the transformation of the rounded cells of the ner mass into a plate of columnar cells, which joins the part of the outer layer lying immediately above it to form the epiblast plate of the embryonic area. (2.) The mesoblast in the mole is formed in two portions :— (a.) A larger portion which has its origin in the primitive streak. (b.) A smaller portion which is derived from the hypoblast situated in front of the primitive streak. I have been unable to distinguish where the latter, or hypoblastic mesoblast, comes into contact with the mesoblast of the primitive streak, and what part these respective layers take in the future development of the embryo. (3.) A neurenteric canal is present in the mole similar to that formed in other types of Vertebrata, first appearing as a pit at the anterior end of the primitive streak, while in later stages it perforates the floor of the hinder end of the medullary groove. I may here add that I have also found ina seven days’ rabbit embryo a rudimentary neurenteric canal in the form of a shallow pit in the epiblast at the front end of the primitive streak. | (4.) The notochord is formed of an axial strip of cells, which un- derlies the epiblast of the medullary groove, and which either never become divided into mesoblast and hypoblast, or in which such a division, if it does take place (as appears not impossible), is very soon lost. This strip of cells is originally continuous laterally with both mesoblast and hypoblast, but as the lateral mesoblast becomes con- verted into definite vertebral plates the connexion is lost. There can, I believe, be no doubt of the connexion of the lateral hypoblast and mesoblast with the notochordal cells in the mole; in the rabbit I am inclined to believe that a similar connexion is present, but my evidence on this point is not yet conclusive. 1881.] On the Rhythm of the Heart of the Frog. 199 II. “On the Rhythm of the Heart of the Frog, and on the Nature of the Action of the Vagus Nerve.” By W. H. GASKELL, M.D. Cantab. Communicated by Dr. MICHAEL FosTER, Sec. R.S. Received December 8, 1881. (Abstract. ) The method of investigation employed by the author is as follows :— The heart with the vagus nerve intact having been removed from the body together with a portion of the cesophagus, a thread is tied to the very apex of the ventricle and another to the loose flap which is dis- closed at the junction of the two auricles when the two aortic trunks are cut away. The piece of the cesophagus removed with the heart is held firmly in a suitable holder and the heart suspended between two horizontal levers by means of the two threads which are attached to the auricles and ventricle. Between the two levers a clamp is placed, the edges of which can be approximated to any degree by means of a fine micrometer screw ; the two limbs of this clamp are placed one on each side of the suspended heart, and by means of the micrometer screw, the tissue between the two edges can be simply held firm or compressed to any extent required. In this way, with the clamp in the auriculo-ven- tricular groove, the beats of both auricles and ventricle are registered simultaneously and separately ; the contractions of the auricles pull the upper lever downwards, those of the ventricle the lower lever upwards. Similarly by varying the position of the clamp the con- tractions of any two adjacent portions of the heart can be studied, as for example, sinus and auricles, base and apex of the ventricle, &c. ; heat, cold, and poisons can be applied to the tissue on the one side of the clamp and not on the other; and under all these various condi- tions the effects of stimulation of the vagus can be observed. The paper is divided into two parts: Part I, on the rhythm of the heart; Part II, on the action of the vagus nerve. In Part I reasons are given for the view that discrete impulses pass from the motor ganglia to the muscular tissue, that, therefcre, the normal rhythm of the heart is dependent upon rhythmical dis- charges from the motor ganglia, and is not due to the production by the cardiac muscle of rhythmical results from a constant stimulation. This follows from the fact that any influence which, when applied to the auricles and sinus alone, causes an alteration in the rhythm of the auricles, affects the rate of the ventricular beats synchronously; while the same influence applied to the ventricle alone, causes no alteration in the rhythm of the auricles or in the synchronism of the ventricular with the auricular beats. Thus heat applied to the ven- tricle alone does not alter its rhythm although it reduces the force of VOL. XXXIII. P 200 Dr. W. H. Gaskell. [Dec. 22, its contractions; while on the other hand, when applied to the auricles and sinus alone, it quickens the rhythm most markedly. Cold, atropin, muscarin, all slow the rhythm when applied to auricles and sinus, but cause no alteration of rhythm except in extreme doses. when applied to the ventricle alone. The author then proceeds to consider the conditions which are necessary in order that each one of these impulses should produce a contraction, and concludes that a due relation must exist between the strength of the impulse and the excitability of the tissue in order to obtain this result. By a comparison of the rate of the contractions of the auricles with those of the ventricle, it is found that the ventricle can be made to beat synchronously with every second, third, fourth, or more auricular beats, or to cease from beating altogether by increasing the com- pression of the clamp in the auriculo-ventricular groove or by heating the sinus and auricles alone without heating the ventricle. The com- monest and most permanent effect is to make the ventricle beat synchronously with every second auricular beat. This same want of sequence between the ventricular and auricular contractions can also be obtained by the application of various poisons to the ventricle alone. A marked difference however exists between the two cases. In the first case, when the ventricle is made to beat with half-rhythm by tightening the clamp, or by heating the auricles and sinus, its contractions are those of a strong vigorous muscle, and are more powerful than when the ventricle was beating synchronously with every beat of the auricles ; on the other hand, the application of poisons to the ventricle does not produce this effect on its rhythm until by the action of the poison the force of the contractions has become greatly reduced. For this and other reasons given in the original paper, the author concludes that either tightening the clamp or heating the auricles and sinus alone diminishes the strength of the impulses passing to the ventricular muscle, and so causes the half-rhythm observed ; while various poisons applied to the ventricle alone produce the same effect by diminishing its excitability, without affecting the strength of the impulses. The conclusions arrived at in Part I can be summed up in the following propositions :— 1. The rhythm of the heart is caused by discrete motor impulses passing to the muscular tissue from certain motor ganglia. 2. In order that each one of these impulses may produce a con- traction of the ventricle a due relation must exist between the strength of the impulse and the excitability of the ventricular muscle. 3. When each impulse is inefficient to cause a contraction of the ventricle, the ventricular muscle has the power of summing up the 1881. | On the Rhythm of the Heart of the Frog. 201 effects of two or more of these inefficient impulses, and so continues to beat rhythmically though no longer synchronously with every impulse. 4. The most satisfactory explanation of this summation process is as follows :—Hvery impulse which is inefficient to produce a muscular contraction increases the excitability of the muscle, and therefore makes it easier for a second similar impulse to cause a contraction. 5. The impulses can be made inefficient to produce contractions syn- chronous with them by lowering sufficiently the excitability of the ventricle, as is seen in the action of poisons, even although the rate and strength of the impulses remain unaltered. 6. The impulses can also be made inefficient, when the excitability ot the muscle is unchanged, by diminishing the strength of the im- pulses, as is seen in the effects of compressing the tissue between the ventricle and the motor ganglia, or of heating the auricles and sinus without heating the ventricle. 7. There is a limit to the extent to which a series of inefficient im- pulses can raise the excitability of the muscle, so that the ventricle can remain absolutely quiescent, even although the impulses still pass to it, when those impulses are sufficiently weakened. | In Part II the action of the vagus nerve is considered, and it is shown that its stimulation produces a most marked effect upon the force of the contractions, both of auricles and ventricle, entirely independent of any alteration of rhythm. The curves obtained can be classified under the three following types :— 1. Complete quiescence of both ventricle and auricles, followed by contractions which at first are scarcely visible, but which rapidly increase in size, until at the maximum they are much greater than before the stimulation of the nerve. From this maximum they very gradually decrease, until the original size of contraction is again reached. 2. During the stimulation no quiescence of either ventricle or auricles, but simply a diminution of the size of the contractions, followed by a rapid and marked augmentation of the contractions beyond the original height, and then a slow gradual diminution to the size obtaining before the nerve was stimulated. 3. No primary diminution, but from the commencement of the stimulation the beats increase in size, and after a time gradually return again to the original size. Between these three types every conceivable variation may occur, so that a series of curves may be selected in which no line of demarca- tion can be drawn between complete primary quiescence, or to use the usual term, inhibition, on the one hand, anda simple primary aug- mentation of the size of the contractions on the other. These curves alone show that the vagus is able to cause a standstill Pp 2 2U2 On the Rhythm of the Heart of the Frog. — [Dec. 22, by diminishing the force of the contraction down to quiescence; this is further shown by the fact that standstill of the ventricle alone can occur while the auricles are beating with accelerated or unaltered rhythm, but diminished force, or even when from the commencement of the stimulation the force of the auricular contractions is in- creased. This same gradation of effect, as the result of the stimulation of the nerve, from absolute standstill to a simple primary augmentation, is seen more or less clearly in the course of each separate experiment ; the stimulations that occur immediately after the suspension of the heart are much the most likely to produce standstill; later ones to cause primary diminution followed by augmentation, and finally aug- mentation alone. The power of diminishing the contractions to standstill appears to last longer after the heart has been suspended at some times of the year than at others. The conclusion is drawn that the variations in the effects produced by stimulation of the vagus on the force of the contractions are dependent essentially upon the condition of the rutrition of the heart ; and possibly for the same cause the vagus tends to lose all power of producing slowing after the heart has been suspended in the apparatus, for in most cases acceleration only is seen, although slowing occurred on stimulation before the heart was cut out, and apparently slowing is more likely to occur immediately after the suspension of the heart than later. The action of the vagus upon the muscular tissue is not only shown by its effect on the size of the contractions, but also by its influence on the excitability and tonicity of the ventricular muscle. When by tightening the clamp the ventricle is made to beat synchronously with every second auricular beat, stimulation of the merve may cause the ventricle during the stimulation to beat syuchronously with every third, fourth, or more auricular beats; and the same alteration in the relation between the rhythm of the two parts above and below the clamp is seen in the case of the contractions of the apex and base of the ventricle, when the clamp is placed midway across the ventricle. Also, when the ventricle is beating with half-rhythm from the action of the clamp, stimulation of the nerve may make it beat syn- chronously with every beat of the auricles for a definite time; and when the ventricle is not beating, either in consequence of tightening the clamp, or of heating the auricles and sinus, then vagus stimula- tion may cause a series of contractions synchronous with those of the auricles. These experiments are to be explained on the supposition that the vagus stimulation diminishes the excitability of the ventricle at one 1881.] Dr. E. J. Mills. On Melting Point. 203 time and increases it at another, and it is also shown that the times of this diminution and increase correspond respectively to the periods when the vagus causes a diminution and increase of the size of the contractions. The action of the vagus upon the muscular tissue of the ventricle is further shown by its power of removing the inequalities in the size of the ventricular contractions, when as often happens, the ventricle is beating with alternately strong and weak contractions. Stimulation of the nerve causes this inequality to disappear when it increases the force of the contractions, and to reappear again when it diminishes that force. The effect of stimulation of the vagus upon the tonicity of the ventricle was studied by the method described elsewhere,* and the author shows that the relaxation between the beats of the ventricle is increased during the stimulation of the nerve, even although the rate of rhythm is not made slower. The conclusion therefore is drawn, that stimulation of the vagus acts upon the muscular tissue of the ventricle in such a way as to diminish its excitability and lower its tonicity, when it reduces the force of the ventricular contractions, while it increases its excitability and possibly also increases its tonicity when it augments the contraction force. Finally, it is shown that atropin removes the whole action of the vagus stimulation, and the effects of the local application of curare, muscarin, and atropin are described and discussed. Tn conclusion, the author sums up the results of these experiments, and suggests that a series of formative processes are going on in both the muscular tissue and the motor ganglia of the heart, similar to those which occur in gland-cells, and that the vagus produces all its effects by increasing the activity of these processes and not because it contains a multiplicity of fibres, each of which possesses a different function. Il. “On Melting Point.” By Epmunp J. Mims, D.Se., F.R.S., Young Professor of Technical Chemistry in Anderson’s College, Glasgow. Received December 6, 1881. (Abstract. ) The investigation, of which the memoir contains an account, was undertaken in order to determine, with considerable accuracy, the * “ Journal of Physiology,” vol. i, p. 452. 204 Dr. E. J. Mills. [ Dec. 22, temperature at which certain organic substances pass from the solid to the liquid state. The apparatus, of which an engraving, on a scale of one-fourth,” is given below, consists of a bath nearly filled with oil of vitriol. In this is inserted a glass funnel, having on its lower edge six equidistant semi- circular cuts of about 5 millims. radius, and, at the end of the neck, four of the same. A thin test-tube, resting freely on the funnel, contains a bath of paraffin oil, in which the thermometer’s bulb is centrally placed; against the bulb, in a little tube separately represented, is fixed the substance whose melting point is to be determined. When the large bath is heated, constrained and regular convection takes place in the liquid; the effect upon the thermometer is such as to cause the mercury to rise with very great steadiness. A preliminary series of researches in thermometry has enabled me to give a series of results completely corrected, and in terms of the air thermometer. * The portion above the cover of the bath is not to scale. 1881. | On Melting Point. 205 2 | After Substance. Wictebteds: | Poggendorff’s ; Air therm. mean. | : correction. iMoluidimne 2.0. oes 006 os 42 “765 42-700 42,°890 Nitrophenol (a) ...... 4.4. °2'70 44°205 44,°392 NaGratolwol cs. 0 > neces 51°305 51-239 51 °407 Dichlorobenzol....... 52 °723 52-657 52 °821 Nitronaphthalin...... 56°175 56 °110 56 261 Dinitrophenol (a) .... 61°778 61 °714 61 °843 | Monobromaniline. .... 61-806 61-742 61-871 | Dinitrotoluol (a) ..... 69 °211 69 °154 69 °252 Di acners 69-571 69 °514 69 °610 Mmanehloraniline eerh. 69 -667 69 610 69 °706 Dinitrobromobenzal.. . 70°598 70 °542 70 °634 Trichloraniline....... 77-052 77 004 77-068 Dibromaniline........ 78 °821 78 °776 78 833 Trinitrotoluol........ 78 °841 78 °796 78 °853 Naphthalin .. 80 ‘061 80°018 80-070 Trinitrotoluol (M).. 80 °524 80-481 80 °532 N. iadibcemobensell | 83 ‘490 83 °452 83 °4.92 Dibromobenzol....... 87 -037 87 °007 87-035 Dinitrobenzol ........ 89-718 89 -693 89 °712 Nitrophenol (4) ...... 111-413 111 -448 111-455 Dinitrophenol (4) .... 111-579 111 -614 111 621 Tribromaniline....... 116 °247 116 -298 116 -319 Trinitrophenol....... 121 °082 121-151 121 °194 Mean probabie error of a result, in terms of the air thermometer, 0°-015. The method of purification adopted was based upon what may be termed the principle of iultiple successive solvents. It is well known that small quantities of impurities are prone to cling to substances with great tenacity; but the observation has most frequently been made in connexion with a single solvent. One can readily conceive that the tenacity with which a given trace of a foreign body is held, under such circumstances, may be in effect constant. If, however, we now transfer the mixture to a second solvent, it may be presumed that the trace will be in a condition of altered adhesiveness, and may be much more readily separable. In accordance with this principle the substances were crystallised from two solvents at least, and the constant melting points of successive fractions recorded. After every fractional crystallisation, pressure was had recourse to for about twelve hours. A glance at the table shows that, on the whole, melting point and formula grow together. The following instances of this law (M.P.=m Formula) are adduced :— 206 Mr. A. R. Forsyth. On the Theta-Functions, [Dec. 22, Substance. Formula. M. P. ™m. Dichlorobenzol ..... CgH,Ch=147 .. 52821 .. 85933 Bromaniline....... C,H,BrN=172 .. 61:742 .. -35971 Trinitrotoluol...... C,H.N,0,=227 .. 80°582 .. °35477 Here the first pair of values of m are almost identical. Itis evident, however, that this simple relation does not generally prevail; indeed, in the case of isomeric substances, melting point may alter widely, while additive formula remains constant. The following are examples of the identification of series by melting point :— M. P. MOP: z-Trinitrotoluol...... 78°853— a-Dinitrotoluol 69°252=9°601 i Trinitrophenol..... 121:194— 8-Dinitrophenol 111:621=9-573 a-Dinitrotolnol 3... 69:°252— Nitrotoluol 51°407=17°845 z-Dinitrophenol...... 61°843—a-Nitrophenol 44392=17°451 The melting points recorded in the memoir are important physical constants, now first determined with a small probable error, and with an apparatus of considerable simplicity. Under no range of ordinary atmospheric pressure or latitude, and in no ordinary interval of time, are these constants likely to become impaired. Hence, if the sub- stances referred to be prepared and preserved with average care, and handled with moderate skill, they constitute in themselves a set of thermometric standards, distributed at mean intervals of about 4° between 42° and 120°. If these substances, or most of them, be at hand, they enable an investigator to at once calibrate and directly refer to the air thermometer any standard mercurial instrument, without the necessary application of any correction whatever. IV. “ Memoir on the Theta-Functions, particularly those of Two Variables.” By A. R. Forsytu, B.A., Fellow of Trinity College, Cambridge. Communicated by A. Cayuey, LL.D., F.R.S. Received December 9, 1881. (Abstract.) The paper of which this is an abstract is divided into four parts, to the whole being prefixed a list of the more important papers dealing with the double theta-functions. Section I treats of what may be called Rosenhain’s theory, and its object is to obtain from a more general basis, and in an easier manner, the results given by Rosenhain in his essay “‘ Mémoire sur les Fonc- tions des Deux Variables et 4 Quatre Périodes,” which obtained the 1881.] particularly those of Two Variables. 207 prize given by the Paris Academy of Sciences in 1846, and was. published in the “‘ Mémoires des Savans Etrangers,” tom. xi. Taking as the definition of the general double theta-function men) — n—c SSE (1 rey tem tug t2nty) 27h Omty) Cnty) g (Ont wae E+ (uty) Se m=——O n=——O and denoting the product of four functions, in which the characteristic numbers and the variables have the subscript indices 1, 2, 3, 4 re- spectively, by ne (}9] there is investigated, by the guidance of Professor H. J. 8. Smith’s. paper on the Single Theta-Functions in the first volume of the “ Proceedings of the London Mathematical Society,” the theorem ame} (» Pye, y= - +(-1) Ie { i 7% Y \ ® { (, re )x, x} +n0{ (*, o. PANS x} +110 { aGuae x. euf(SEP Yer} [ue (CSE emefE Hr} [me OHH Y] +(—1)?" into +(—1)4%”" into me (641 SY f me t(, 41 41)% x} soef@tryer} | mef(A] nef cx} |-nef(Ai"H,)57} ne) (“+% es a +n0{ piconet in which 2(Ay +A )=2(Az+ Ag) =2( Ag+ rg) =2(Ag+Ag) =A + Ag+ Agty=ZA’, and similarly for », p, v; and . 2(Xy + a) =2(Xo + wy) =2( Xs +03) =2(Ky +a) =4 + eq tagtey, 208 Mr. A. R. Forsyth. On the Theta-Functions, [Dec. 22, and similarly for the y’s. Since the assumption has been made that the sums of the four similarly situated numbers in the characteristics of the functions are all even, the equation comprises 4,096 cases (Slo). This general result seems to be new, but numerous particular cases occur in Rosenhain’s paper. All the important parts of his theory are deduced, viz., the quadratic relations between the constant terms in the ten even functions; the nine ratios of all but one of these by that one are expressed in terms of three independent constants hy, ko,. k,; and it is proved that the fifteen quotients of all the functions but one by that one can be expressed in terms of two new variables 24, &, the expressions being given. The connexion between 2, #., and £,Y 18 = ("At R a a A+Bz ; V7 V7 ie I. 1 A'+B% | cal 2A’ B’z _: WR eas , where ZL=2(1—z)(1—k,2z) 1—h,*z) (1—k,2), and A, B, A’, B’ are perfectly determinate constants. The quadruple periodicity is investigated at the beginning of the section; and afterwards definite-integral expressions for the periods are obtained, as, for example, K=|'At =a) 0 and it is proved that K satisfies a linear differential equation of the fourth order in each of the quantities hy, ka, ks. It may be mentioned that in dealing with the particular functions a current-number notation Jj), 3, .- . . 4; 18 used in preference to the cumbrous ® a ol Section II gives the expansions of all the functions (1) in trigonometrical series, (11) in ascending powers of w and y. Much use is throughout made of a theorem f r _ 2KA log r d? ® he: a y | =e ma) dedy Ou, r(&) Oy, p(y) (O., x (2), 9%,» (y) being single theta-functions) proved by means of the known values of the single theta-functions. From this many properties are deduced :— 1881.] particularly those of Two Variables. 209 (a.) The expressions for the four pairs of conjugate periods, two actual and two quasi; (8.) The product theorem of Section I is obtained by means of the product theorem proved for single theta-functions by Professor Smith in the paper previously mentioned ; (y.) By means of the differential equation which @ is known to satisfy (see ‘‘ Cayley’s Elliptic Functions,” § 310), it is proved that the general function ® satisfies two equations in #, y of the form d2® d® ——— 2a kh’? — 2hk 2—_ eat ts —0, da k, k', E having the usual connexion with 6,,,(#). These equations are also investigated from the definition as well as d® 2KA PO _ dr a da dy which it is obvious from the theorem of this section that ©® satisfies. (6.) Expressions for all the constants occurring in the expansions of all the functions in powers of w, y are obtained. If we write 1 T= %— 5 (Boo 189) ty 1819 GZ BS 08 € + ok (No, 0» No HONG) No,s) cy No.on) (&, ye Sn oS it is proved that C&y=Ay, ° KA}, N == ieee dq? 0, 28 A dp!” “sdiq’s 0» YW KAS ow \2-5) 2(s+1) qztl Bene No, 6+1— (z as dp’ ”sdq's*1 ce -K A’, where p =log p, q' =log q, 7” =2 log 1, a= ae " (aa ‘dq’ 7) j with a similar expression for Ao. Section III forms the expression of the addition-theorem. Although no addition-theorem proper exists for theta-functions, that is to say, although ® (#+£, y+) cannot be written down in terms of func- tions of w, y and of £, 7, an expression is obtainable in every case for b(a+€, y+)’ (e@—é, Yin) ®, ®’ being either the same or different functions. Since any one 210 Mr. A. R. Forsyth. On the Theta-Functions. [Dec. 22, function of the sum of two pairs of variables may be combined in a product with any one function of the difference of the same pairs, 256 equations are necessary to give the complete expression of the theorem. These are written down in sixteen sets of sixteen each, that. which is common to each set being the function of the difference of the pairs of variables. Denoting by 0... 9a+£, y+), O'...d(a@—é, y—7), S's G9 (@y Os 0 6 as) Gp) one such equation is 69° O09) = O97 I? + Oy? 7? + Ory? 10° + O13°I 3" where cy is the value of J, when #, y are both zero. The obvious analogy with the case of the single theta-functions ©6(0) 0(u-+v) O(u—v) =0°(u) 02(v) —H?(w)H2(v) (using the ordinary notation) need hardly be pointed out. In Section IV many of the properties ale aey proved for the double theta-functions are generalised for the “‘r”’ tuple theta-functions. Among these are :— (a.) The periodicity ; (8.) The product theorem, which gives the product of four func- tions as the sum of 4” products of four functions; and from it several general equations are deduced ; (y.) The analogue of the main theorem of Section II, which is for the “7” tuple functions C=? =P d2 t=r Xr d onele r u198 K K lo | ST. 4 Dp 12 oy? awl: V5 Vo, oo 0 9 lp ce — OC a 2 Sete dz,dc 1 Oy, v(t) C1) LAoXN O90 1 LR ca and this is used, as before, to obtain (6.) The r differential equations of the form WO | oy. tr( ha? E, eat ref = i da, da, dk, and the $r(r—1) of the form db 2K Ky PO _ " ‘dps, t qe dxdx, all satisfied by ® ; and to indicate a method of obtaining the constants in the expansions of the ®’s in powers of the #’s. 1881.] On certain Geometrical Theorems. Dike V. “On certain Geometrical Theorems. No.1.” By W. H. L. RussEwu, F.R.S. Received November 12, 1881. (1.) The following proof of the equation to a circle inscribed in a triangle, expressed in trilinear co-ordinates, is very short and simple. Let «, B, y be the sides of the triangle, A, B, C the opposite angles, and let Pa? + mB? + n2q?—2mnBy—2nlya—2liaB=0 be the equation to an inscribed conic. Then when this conic is a circle, the centre is given by the equations 2=@8=y, and the equation to the line joining the centre, to the point where y touches the conic, that is to the point lz—mB=0, y=0, is la—m6 + (m—l)y=0. Now, when the conic is a circle, this ling must be perpendicular to y; hence from the condition that two straight lines may be perpen- dicular to each other (Salmon, ‘‘ Conic Sections,” 6th edition, Art. 61), m—l=lcos B—m cos A, a Mon Me ff Sak eee ; > A 9B 9 OC €OS- = COS 2 cos 2 2 which gives for the required circle a” cos* = + B? cos* _ age COS .: — 2Bry cos” = cos? — 2a8 cos® = ces? = — 2ary cos? “ cos? eat (2.) The following theorem is given by Dr. Salmon in his “ Higher Plane Curves ”’ :— If through any point of inflexion A in acurve of the third order there be drawn three right lines meeting the curve in ab, df, ec, then every curve of the third degree passing through the seven points A, a, b, d, f, c, e will have A for a point of inflexion. It follows from this that any curve of the third degree described through the nine points of inflexion of a cubic will have those points as points of inflexion. Dr. Salmon has given a geometrical proof of this theorem, and this is the only demonstration I have ever seen. I have, therefore, obtained the following analytical proof, which !possesses, I think, considerable beauty. 212 Mr. W. H. L. Russell. [Dec. 22. Let A be the origin, Adf the axis of (x), Azc the axis of y. Let y=Ilx be the equation to Aab, y=ax+b6 the equation to cd, y=ne+ b the equation toca, y=cx+e the equation to ef, y=ma+e the equa- tion to be, then we may find the equation to ad, y(l—n+a) —lax—lb=0; and similarly the equation to Df, y(l—m +e) —lew—le=0. In this way it will easily be seen that the six points, a, b, c, d, e, f, are completely determined, and consequently the equation to a curve of the third degree passing through them (see Salmon, ‘‘ Higher Plane Curves,” Art. 162) is ab.cd.ef+0.ac.be.df+o.ad.bf.cet+w.ae.bd.cf=0. But since ab, df, ce pass through the origin y=0, and the equation. becomes ab.cd.ef+0.ac.be.df+¢.ad. bf.ce=0, and consequently writing down ab, cd, ef, ac, be, df, ad, bf, ce, as given | above, we have as the equation of the required cubic— (y—lax)(y—ax—b) (y—ca—c) + Oy (y—nxe—b)(y—mae—e) + pu(y(l—n + a) —lax—lb)((l—m + ¢)y —lew—le) =0 ;sx differentiating this equation, and putting «=y=0 to determine the value of “ at the origin, we have a DOG) Rp espe) dx Mipy ; 5 OP : wipe Differentiating again, and putting ay =0, a—=y=0, since the origin da? Re 1881. ] On certain Geometrical Theorems. 213 is to be a point of inflexion, we shall have— 2 a ae eb heb + (Lb )ob de e Cpe! pl Jae+ = (l+c) Fa pl*)ec dy” 00 Y + opt — bo! + gel(I—n +a) +. 6b1(I—m + 0) eas Be eb mb Sel ve + dbl ( DDE) or substituting for 1—¢/*, and dividing by 7, We have— ee (eae (1-+0)ae +o! .b—(L4-e)b + Lo) eb dx dix +00 —ne0 +6 “1 —mb0-4+G(1—n-+a)el+o(I—m-+e)b1=0. @ a@ Again substituting /—@l* for (1+ ae and reducing, we obtain aL the equation (0+ 1p) (ae+cb—ne—mb) =0. Hence, if ae+cb—ne—mb vanish, the origin will be a point of in- flexion, whatever values we give to @ and ¢; hence the theorem is true. (3.) From any point six tangents can be drawn toa curve of the third order ; two of these are at ai angles to one another, determine the locus of the point. Substitute for y in the general equation of the cubic m(a—£)+7, arrange the terms of the resulting equation according to powers of (w) and form the discriminant, equate the discriminant to zero, and we shall have an equation of the form— m§—am? + bm*—cm? + dm*?—em+f=0. Let M +my+M3+im,+mM;+me=a, MyM + (M+ Mg) (Mz + Mz + Mz + Mg) + Mgr, + MgMz + MMe + mM; +MMg+ m:1.= bd, MyMy(Ms + 114+ Mz + Me) + (m+ mq) (mgm, + MN; +mging +mym,; + mymg + msm 6) +MmzmmM; + MMM gt M3 Me + M4MzMe=C, MMy(MsIr4+ M3M- + MgMg + MyM; + MyiNg + MMe) + (m+ mz) (mgmym; + mmm, + maMzMg + MMM) +MgMNzMe=d- M1Mz(MgM4Mz + MIN Ng + MgM=Mg-+ MyMzMe¢) + (m+ mg) (mym,m,M¢~) =e, MMyMN3N,M-M,=f. 214 On certain Geometrical Theorems. | Dec. 22, Since two of the tangents are at right angles to each other, we shall have mm,+1=0, and let m+m.=yn, =mg=p, Zm,m4=4, =Im,mMyn,=r, mznym;mg—=s. Then substituting, we have the follow- ing equations :— ; yy 1 ee a Pree oh (!E) —gtprts=d-. - 2G): —l+tpptq=b... (), —P+psS=e. :. ol oe —ptmgtr=c .. . (8), iat Pees CE From these equations we obtain at once— p=a—p. r=f(p—a)—e, = gq=1+b—pp=1+b—ap+p?. Hence we have, substituting in (4)— (f+1)p?—(a+2afte)p+ (1+6)+fa?+aet+f+d=0 . . (7%). Also substituting in (3)— p®?—2ap?+ (a®+b—f+2)p—a(b—f+1)t+e+e=0 . . (8). From (7) and (8) we easily obtain two equations of the form— Ap? +Bp+C=0, A'p*?+ B'p+C’=0, then the eliminant is at once seen to be— (A’/C—C’A)?+ (BA’—AB’) (BC’—CB’)=0, the equation to the required locus. T have not thought it necessary to write down the values of a, 6, e, é&c., as they are obtained by rules perfectly well known. Note by W. SPOTTISWOODE, P.R.S. The second theorem in the foregoing paper follows also as an imme- diate consequence of a formula given by Cayley in his ‘‘ Seventh Memoir on Quantics” (“ Phil. Trans.,” 1861, p. 286). If U repre- sent the cubic and HU its Hessian, then, as is well known, HU passes through the points of inflexion of U. Also, the function 20 +6f8HU will represent an arbitrary curve of the third degree passing through the same points; and, on the same principle as before, its Hessian will pass through its poimts of inflexion. Now the formula in question is— H(eU+6BHU)= = 62(1, 0, —248, . . )(a, B)*.U —66,(1, 0,—248, . . )(a, B)*. HU. 1881.| Prof. J.C. Malet. Ona Class of Invariants. 215 But this equation is satisfied by U=0, HU=0; consequently the equations aU+68HU=0, H(«zU+68HU)=0, are both satisfied by the relations U=0, EW 0: Hence the theorem given in the text. VI. “On a Class of Invariants.” By JoHN C. MALET, M.A., Pro- fessor of Mathematics, Queen’s College, Cork. Communi- cated by Professor CayLey, LL.D., F.R.S. Received December 14, 1881. (Abstract. ) This paper is concerned with two kinds of functions of the coeffi- cients of Linear Differential Equations, which have certain invariant properties. In the first part of the paper it is shown that every Linear Differen- tial Hquation possesses a certain number of functions of the coeffi- cients which are unaltered by changing the dependent variable y to yw where u is any given function of wz, the independent variable. These functions bear remarkable analogies to functions of the differ- ences of the roots of ordinary algebraic equations, and many problems, provided they involve only the ratios of the solutions of the differen- tial equation, may be solved in terms of them; for example, the condition that two solutions 7, and y, of a linear differential equation of the third order should be connected by the relation y,=y,x is expressed in terms of two such functions of the coefficients of the equation. This problem is analogous to that of finding the discrimi- nant of an algebraic binary cubic. The second part of the paper is concerning functions of the coeffi- cients of Linear Differential Equations which are unaltered by change of the independent variable, and the theory of these functions is applied to the solutions of problems involving only relations among the solutions of the equation without the independent variable. In this part of the paper it is shown how to form the condition that the three solutions 4, Yo, y3 of a linear differential equation of the third order should be connected by the relation y,y,=y3", which relation, involving only ratios of the solutions, and not containing the independent variable, can be expressed in terms of either class of the functions of the coefficients considered in the paper; these two methods of writing the condition are accordingly given. VOL. XXXITII. Q 216 Mr. 8. A. Hill. On the Constituent of —_[Dec. 22, VII. “On the Constituent of the Atmosphere which absorbs Ra- diant Heat.” ByS. A. HILL, B.Sc., Meteorological Reporter for the North-Western Provinces and Oudh, India.” Com- municated by Lieut.-General R. StTRAcHEY, R.E., F.R.S. Received December 14, 1881. Notwithstanding the ingenuity with which Dr. Tyndall has made use of the most recent physical appliances to support and confirm the results of his classical researches concerning the behaviour of gases and vapours with regard to radiant heat, his conclusions, in so far as they relate to the comparative diathermancy of dry air and water vapour, have not yet met with general acceptance among meteorologists. There is even, on the part of some, an evident reluctance to accept the decision of laboratory experiments on the question of atmospheric absorption as final, however ingenious, varied, and consistent with one another the experiments may be. I have, therefore, attempted to approach the question from another side, and to determine, if possible, what constituent of the atmosphere has the greatest absorptive power, by means of the actinometric observa- tions so carefully made at Mussooree and Dehra by Messrs. J. B. N. Hen- nessey, F'.R.S., and W. H. Cole, M.A., in conjunction with the records of meteorological observations made at the same or neighbouring places in the same months of the year. The actinometric observations were made between the 27th October and 4th November, 1869, and between the 31st October and 19th November, 1879. Abstracts of the results have been published by Mr. Hennessey in the “ Proceedings,” vol. xix, p. 229, and vol. xxxi, p. 154. In both years the observations were made with two actinometers of the Rev. G. C. Hodgkinson’s form, marked A and B, each of which appears to have remained absolutely unaltered during the ten years. The results taken from Mr. Hennessey’s tables are those expressed in units equal to a tenth of a millimetre of the scale of the instrument A, glass off. The observations which serve to throw most light on the question under discussion are those of the long diurnal series, from 8 A.M. to 4 p.m., made on the 4th November, 1869, and the 12th and 14th November, 1879. In Tables I, IJ, III, the observed values of the radiation received in three minutes at each hour* are compared with certain symmetrical values computed in the following way. It has been assumed that Jamin and Masson’s law of absorption holds good for each day at both stations; that is to say, that the logarithm of the heat received varies inversely as the thickness of the atmosphere traversed, or, in other words, that the quantity of heat * On the 4th November, 1869, the mean time of each set of observations was several minutes after the exact hour. The values given in Table I have been in- terpolated from Mr. Hennessey’s figures by means of parabolic formule extending over three hours at a time. 1881.] the Atmosphere which absorbs Radiant Heat. 217 absorbed by each unit thickness of the absorbent substance (supposed homogeneous) is proportional to the total heat which falls upon it. ‘This rule was long ago found by Pouillet to be approximately true of atmospheric absorption. The thickness of atmosphere to be traversed by the solar rays at various angles of incidence has been taken to be simply proportional to the secant of the sun’s zenith distance. If the vertical thickness of the absorbent atmosphere be taken at z$,th of the earth’s radius, the error of the preceding assumption is almost insensible for the inclinations in the tables; and below an elevation equal to ;1,th of the radius lie 68 per cent. of the dry air, and 995 per cent. of the water vapour of our atmosphere. If, then, R stands for the total radiation that would fali upon the actinometer at the limit of the atmosphere, and r for the observed radiation at the place of observation, when the sun’s zenith distance is z, we may put log + =log R—K sec z, where K is a coefficient the antilogarithm of which represents the fraction of the total radiation that would be absorbed by @ vertical column of the air above the place at the time of the observa- tion. Assuming the K to be constant for each day at each station, 1 have computed the values of log R independently from the sets of obser- vations made at the two stations; and then, taking the most probable value of R for each day to be that derived from the mean of the two log R’s, in which the logarithm deduced from the observations at the upper station* is given double weight, I have recomputed the coeffi- cients marked Kj, and Kp respectively, and finally worked out the symmetrical values of r+ for the hours before and after apparent noon. Table I.—4th November, 1869. — Mussooree. Dehra. j Hour. oes eon See z. | robs. |r comp.| Diff. | Sec z. | r obs. |r comp.| Diff. SAM. ....| 3°57 842 817 —25 | 3°54 715 645 = 79) as 2°21 934 929 — 5 | 2:20 807 801 — 6 7 10 ,, 1°71 990 973 ie Le 70 870 868 — 2 al, i 5On | LOGON MIMNOOW IN 7 le4oe | 905, 101898 he ay Noon 1°43 988 999 + 1d 1-43 914 907 — 7: 1 P.M 1-50 984 993 One eto) 200 898 — 2 55 1°71 967 973 Oe) E70 852 868 +16 | Bis 25 2°21 920 929 9) 92720 786 801 +15 9 3°57 799 817 | +18 | 3°54 584 645 +61 Mean R= 1143 log R=3°05804 Ky = 04078 for decimal logs = °09390 5) aatural ~,, Kp = °07027 » decimal ,, = °16157 ,, natural Ky Ge = °5803 99 * Dehra is 2,229 feet above the sea, and Mussooree 6,937 feet. Q 2 218 Mr. 8. A. Hill. On the Constituent of — [Dec. 22, Table II.—12th November, 1879. Mussooree. | Dehra. Hour Appt. time | Sec z. | vr obs. | rcomp.| Diff. | Sec z. | robs. |rcomp| Diff. an - —|———- a be an zs 8 am. .....|-3:90.|. 744 1 736 | — 8 || 3-89 || 622.) ‘GlOnemeee 9,, | 2°36 | 873°) 8520 | et 12-34" 764 | 762 ne LOR, 1°80 907 | 898 ie HLa79 817 824 + 7 11) es 1°56 O25 ers. — 7 1°55 851 853 ieee Noon 1°50 | 934 | 924 | —10 | 1:49 | 850 | 860 | +10 1 P.M 1°56 915 | 918 Teco aoe 840 853 +13 a 3 1-80 876 : 898 +22 | 1°79 84:7 824 —23 By ap 2°36 832 : 852 +20 . 2°84 771 762 — 9 . 3°90 | @27 fee = 9 3489 596 610 +14 | Mean R= 1064 log R=3-0271 Ky = °04106 for decimal logs = 09454 2 inatburaler. Kp = °06209 », decimal ,, = °14297 », natural ,, Ku Te 661 Table II].—14th November, 1879. Mussooree. Dehra. Hour. Appt. time. | | | See z. | 7 obs. |7 comp.| Diff. | Sec z. | 7 obs. |r comp.| Diff. Shs Sri) SI 785 762 —23 | 3°97 639 617 — 22 9.,, ..+-| 2°38 | 888 | -892 | + 4 | 2°37 | 766 |) 7S8qnnimueaem LO, testeus alae 941 941 0) Si 848 855 + 7 less “ieee eles 966 963 — 3 1°58 883 884: + 1 Noon sss | EOL 978 970 — 8 1 5 892 894. +2 LPM. amyl aes 947 963 +16 1°58 899 884 —15 Dis, Jeseulb Lee 938 941 + 3 SE 849 855 + 6 S55 | Poem) AEROS 873 892 +19 2°37 780 786 + 6 BPM 82 oki | 3°99 762 762 (ie eye 17/ | 620 617 — 3 Mean R= 1123 nearly log R=3 050483 Ky = °04231 for decimal logs = '09742 »» naturale, Kp = °06546 », decimal ,, = °15063 Peurygvarnl -. Kur kn 644 These tables suggest two independent methods of inquiring which among the atmospheric gases has the greatest power of arresting 1881. | the Atmosphere which absorbs Radiant Heat. 219 radiant heat. We can inquire which constituent of the atmosphere is subject to a diurnal variation most resembling that of the absorption coefficient, and also which constituent is distributed vertically in a manner most closely approaching to that of the absorptive substance. If the coefficient K were truly constant for each day, as has been assumed, the positive and negative differences between the observed and computed values of r should be irregularly distributed ; but we find that, almost without exception, the computed values are too low in the forenoon and too high in the afternoon at Mussooree, while at Dehra there is no such regular order in the differences. The excess of the morning over the afternoon radiation at Mussooree and their approximate equality at Dehra are very clearly seen in the averages of the three sets of observations, which are the following :— laleithean es Saar 8 9 10 Wi 12 138 14 15 16 Mussooree ..| 790 | 398 946 964: 967 949 927 875 763 Dehra ......| 659 | 779 | 845 880 | 885 | 880 | 849 | 779 | 600 The departure from complete symmetry at Dehra is due chiefly to one observation at 4 p.m. on the 4th November, 1869, when probably there was a slight haze partially obscuring the sun. The absorption of heat by the atmosphere on a clear, calm day cannot be, in any appreciable degree, a mere apparent effect due to the scattering of the rays brought about by disturbances set up in the atmosphere through heating from below; for any variations in the amount of such scattering must be even more apparent at the lower station that at the upper one, because, to get to the lower station, the rays must pass through more of the disturbed atmosphere. Moreover, such disturbances, and the apparent absorption caused by them, would probably be at least as great during the hours of rising temperature (up to about 1 p.m.) as when the temperature is falling. The increased absorption of the afternoons at Mussooree must therefore be due to the fact that more of the absorbent substance—whatever it be—lies above the level of the station in the afternoons than in the mornings, while above the lower station the total quantity of this substance is practically constant threughout the day ; that is to say, the absorbent substance is carried upwards during the day and probably sinks down- wards again at night. Such an upward movement of the total atmosphere occurs under the influence of diurnal heating, but what proportion of the air that is lifted above Mussooree by expansion from below remains there cannot be exactly determined. The barometer falls from 10 a.m. to 22%) Mr. 8. A. Hill. On the Constituent of — [Dec. 22, 4 p.m. at all elevations where observations have been made in the Himalaya, as it does on the plains. In any case, the fraction of the total atmosphere which accumulates above Mussooree during the day hours must be a very small one, and its influence in increasing the absorptive power of the upper atmosphere may be safely neglected. With water vapour the case is different. This diminishes so rapidly as we ascend* that, if it be the chief absorbent substance, a small variation in the quantity of it lying above the higher station will con-. siderably affect the absorbing power there observed. In the following table the value of Ky for each hour of observation, computed from the mean of the three series, is compared with the mean hourly values of the barometric pressure and vaponr tension for November at Simla, a neigh- bouring station of nearly the same altitude, and with the vapour tension, and cloud proportion observed at Roorkee, a station 40 miles S.S W- from Mussooree and 887 feet above the sea. General Boileau’s ob- servations at Simla in 1843-5, from which the figures for that station have been taken, were made inside a house, and do not strictly repre- sent the variations in the humidity of the external air. The normal variation of humidity in the upper air may, however, be inferred with some approximation to the truth from the variations of cloud; for though the days of observation were without cloud, like most days in November in North India, there is no reason to suppose that the diurnal movements of the vapour were different in direction on those days from what they are when the humidity is so high that clouds are formed. Table LV. Absorption | Barometric Vapour Cloud Vapour TB Lats coefiicient. pressure. tension. proportion. tension. Mussooree. Simla. Simla. Roorkee. Roorkee. 8 A.M 03862 23-323” -166” 0-99 °346” Opeeyr7.e "03966 23 °349 "172 0:90 °367 Op -03908 23 °360 179 0°80 odes hier’ “03969 23-353 186 0°81 -372 Noon "04051 Zo aoe | °194. 0:90 *362 1PM *04.4.09 23 °307 "198 1°10 “344 7a} OP ns °04.4.05 23 °283 *200 IL, O24 °332 BY ae anulen canis °04.416 23 -267 *202 1-26 "332 Arie dd -O4264 23-259 204. 1-23 “354 | It will be seen from Table IV, and from the diagram below, that the variation of the absorption coefficient is similar in its chief feature—the increase from morning to afternoon—to that of the * See Strachey, “ Proe. Roy. Soc.” (vol. 11, p. 182). 1881.] the Atmosphere which absorbs Radiant Heat. 221 vapour pressure observed at Simla, but totally different from the variation of the barometric pressure; while the absorption curve agrees closely with that of the humidity of the upper atmosphere as indicated by cloud, even in minor points like the decrease at 10 a.m. SA BAR./PRESS. Rcoee iP TEIN.| < | t | | | ee ee OEFT./! Also, since the hourly observations at Roorkee show that the pressure of vapour there is less in the afternoon than in the morning, it is probable that the variations, both above and below, are caused by an upward movement of the vapour during the day. Such a movement would not affect the absorption of heat by the whole depth of the atmosphere, if water vapour be the chief absorbent substance, and we find that at Dehra the absorption in the afternoon is little, if at all, ereater than in the morning. ‘The evidence of the diurnal variation, therefore, points strongly to the conclusion that water vapour is the chief absorbent. The question may be answered more directly by the second method, the determination of the law of vertical distribution of the absorbing matter. Since both stations lie above the dust-haze so common over India in the cold weather, and since the days of observation were free from. cloud, we may assume that the absorbent substance we have to deal with is a gas distributed according to the barometric formula; and therefore the observations at two places suffice to determine the law approximately. We have, then, for each day, log Ky= Al og Ky— = where Ah is 4,708 feet and C is a constant for the day Computing C in this way for each day, and also C, and Cy, for the 222 Mr. 8. A. Hill. On the Constituent of — [Dec. 22, dry air and water vapour respectively, taking an 1 a where f is the vapour tension, and B the height 2 y of the barometer corrected for vapour tension, we get the following values :— Date. C C, 4th November, 1869 ........ 19,922 64,409 17,210* “— 12th =, 187 ee 26,213 66,370 26,814 | ih eter 24,840 66,066 25,499 | Mean .:.s... Spee eee 23,658 65,615 23,174 | In computing C, the vapour tensions observed at the Meteorological Observatory of Roorkee have been combined with those of Dehra, because the latter seem to be somewhat too great at all times of the year in comparison with those for other places in the Himalaya at nearly the same altitude,t while Roorkee is generally a little too dry. In any case, with such a variable element as water vapour, it is best to deduce the law of distribution from as many observations as possible. | The difference between the values of C and C, is so small, con- sidering the nature of the observations, while that between C and Q, is so very great, that there can be very little error in agreeing with Dr. Tyndall that the absorptive power of dry air is sensibly nothing, and that the total absorptive power of the atmosphere is due to the water vapour it contains. The true absorption coefficient at sea-level, on the supposition that the absorbent substance increases in density according to the same law as between Mussooree and Dehra, appears to have been a good deal less on the two days of observation in 1879 than the mean value found by Pouillet in 1838, while its value on the 4th November, 1869, differed but little from Pouillet’s mean result. Pouillet found the absorption of a vertical column of transparent atmosphere at Paris to vary between ‘18 and ‘27 of the total incident radiation, the mean being about °24. From Mr. Hennessey’s observations the co- efficient for Naperian logarithms at sea-level appears to have heen * Computed from the observations made at the Meteorological Observatories of Dehra and Roorkee, and at Chakrata, 30 miles north of Mussooree and 7,160 feet above the sea. No observations of humidity were made at Mussooree on this day. + This has been pointed out by the writer in a paper on the meteorology of the North West Himalaya, published in the “ Indian Meteorological Memoirs,” vol. i. 1881.] the Atmosphere which absorbs Radiant Heat. 223 209 on the 4th November, 1869, and ‘174 and ‘185 respectively on the 12th and 14th November, 1879. If the differences in these values of the total absorption be caused entirely by variations in the quantity of aqueous vapour in the air, the fraction of the total incident heat which is arrested before reaching the ground will be a direct function of the vapour tension at the place of observation, and an inverse function of the rate of diminution of the vapour tension with height. We may suppose it to be simply proportional to the total quantity of water vapour over the place of observation. This has been shown by Dr. J. Hann* to be equal to a depth of water, {X oe — x ‘4343 C, where f is the vapour pressure av expressed in units of height of mercury, and C is the constant of the vapour formula in metres. Neglecting the temperature coefficient, which should probably enter into © also, and reducing to English measure, the quantity of rain that would be formed by the complete condensation of the vapour over any place is given by the formula, Q=f x 00014 C inches, where f is expressed in inches of mercury, Q in inches of water, and C in feet. At Mussooree, on the days of obser- vation in 1879, the several quantities had the following values :— Date. K fF C Q 12th November ....-.| 04106 221” 26,814 ft. 829” 14th 7 es 042811 -183 25,499 653 | If now K=aQ, the value of « on the 12th November is found to be (0495, and on the 14th, ‘0648. The fraction of the total radiation absorbed from day to day therefore does not bear a constant relation to the quantity of aqueous vapour in the air; and, consequently, it seems probable that the quality of the sun’s heat is subject to con- siderable variatious from day to day. If this be so, it will be impos- sible to arrive at comparable actinometric results from a few observa- tions about apparent noon each day, unless the observing station be sufficiently elevated to lie above the greater part of vapour atmo- sphere. Unfortunately no hygrometric observations were taken at Mussooree in November, 1869, so that it is impossible to determine precisely, from the actinometric observations made there by Mr. Hennessey, whether the radiation emitted from the sun was more or less sus- ceptible of absorption in 1869 than in 1879. At Dehra, however, the * “ Zeitschrift fir Meteorologie,’’ Band IX, page 199. 224 Mr. 8. A. Hill. On the Constituent of [ Dec. 22, psychrometer was observed every day at 9.30 a.m. and 3.30 P.m., and from these observations, in conjunction with the figures already given, we can find an approximate value of a for the 4th November, 1869, as well as for the two days in 1879. In the following table the quan- tities from which a is computed and its value for each day are shown :— Date. K if Cz Q, o 4th November, 1869.. °07027 344” 17,210 it. *829” ‘0848 12th ,, 1879..| 06209 | -375 26,814. 1-407 | -0441 14th sy eee pec OGo46 302 25,499 1-078 "0607 The vapour tension observed at Dehra is a strictly local phenomenon, as has been above pointed out, but still the values of a for the two days in 1879 accord so well with those deduced from the observations at Mussooree, that there can be little doubt that water vapour had a greater absorbent effect on the radiation of the 4th November, 1869, than on that emitted from the sun on the other days. From the observations made simultaneously at Mussooree and Dehra, for several days near apparent noon, we may perhaps deter- mine approximately whether the mean emissive power of the sun was greater at the beginning of November, 1869, or in November, 1879. There are only three quantities to determine for each year, the total radiation at the limit of the atmosphere, the absorption co- efficient for Mussooree and the same for Dehra, and we have three relations between these quantities :— (1) Log R=log ry + Ky sec zy, (2) Log R=log rp + Ky sec Zp, 4,708 feet (3) Log Ky=log Ky — G In (3) we may take C to be the constant of the formula for water vapour, which, for 1869, may be computed from the observations at Roorkee, Dehra, and Chakrata. From Mr. Hennessey’s tables and the Meteorological Observatory records, I find the following mean values for the required data :-— Year. Mt rp Sec zu See zp C. | 1869 980 902 1:401 1:398 19,077 | 1879 954 887 1°475 1471 25,030 1881. ] the Atmosphere which absorbs Radiant Heat. 225 These data yield the following results :— Year. R. Ky Kp True K at sea-level. 1869 1095 03454 "06094 1836 1879 1093 "03995 ‘06160 1741 As far as we can judge from seven days’ observations in 1869 and sixteen days in 1879, it would seem that the mean radiation of the sun, and the mean absorption of the atmosphere lying above Dehra were practically the same in the two years; while the absorption at Mussooree was slightly greater, and that at sea-level somewhai less in 1879 than in 1869. On the mean of all the days the quantity of water vapour in the air above Dehra was equal to ‘846 inch of rain in 1869, and 1:174. inch in 1879; and the corresponding values of a, the coefficient of absorption for common logarithms, when the water vapour is equal to an inch of rain, were ‘072 and ‘0525 respectively. The vapour tensions at Dehra are of too local a character to admit of any safe inference from these figures; but, as far as the evidence goes, it points to the conclusion that the radiation emitted by the sun during the days of observation in 1869 was more readily absorbed by water vapour than that emitted in 1879. It is to be hoped that the observations which are to be com- menced next year at Leh—a station 11,500 feet above the sea—that is, lymg above four-fifths of the absorbent atmosphere—will enable us to solve the all-important problem whether the sun’s heat varies. to any appreciable extent or not; but simultaneous observations at a lower station, such as Mussooree, will be required to settle without doubt the further question, whether there is any sensible variation in the quality of the solar rays, as tested by actinometric methods, that can be compared with the changes in the absorption lines which are observed in the spectra of spots. Since writing the above, I have seen a report of a lecture* by M. Violle, Professor at the Faculté des Sciences, Grenoble, in which. the lecturer described some simultaneous observations made by him- self and another at the summit of Mont Blane and Grenoble, and at the Grands Mulets and Glacier des Bossons, on the 16th and 17th of August, 1875. M. Violle’s values for the heat received in a minute by a square centimetre of surface exposed perpendicularly to the sun’s. rays are given in calories in the following table :— * “ Revue Scientifique,” April 6, 1878. 226 Presents. [ Dec. 8, Altitude. Heat received Deine Le (feet). per minute. August, 1875 ....-.| Limit of atmosphere .... P 2°54 Pee lGthees.. .|) Mont Blaneenrn sense 15,780 2°39 eelat cee. |) Grandss\iulets meee 10,010 2°26 17th ......{| Glacier des Bossons...... 3,940 2 02 L6the... «7... Grenobleg ste ee es 700 18 9) From these results M. 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India Office. Synopsis of the Results. Vol. VII. 4to. Dehra Dun 1879. The Survey. Kiel :—Ministerial-Kommission zur Untersuchung der deutschen Meere. Hrgebnisse der Beobachtungsstationen an den deut- schen Kiisten. 1881. Hinleitungsheft und Hefte 1-5. Oblong, Berlin 1881. The Commission. London :—Admiralty. The Nautical Almanac, 1885. 8vo. London 1881. The Lords Commissioners. Board of Trade. Report on Proceedings under the Weights and Measures Act, 1878. 4to. [Zondon 1881]. Mr. H. J. Chaney. Madrid :—Comision del Mapa Geoldgico de Espafa. Memorias. Provincia de Salamanca. 8vo. Madrid 1880. Boletin. Tomo VIII. Cuaderno 1. 8vo. Madrid 1881. The Commission. Paris :—Observatoire de Paris. Annales. bservations. 1870, 1878. 4to. Paris 188]. Rapport Annuel sur VEtat de l’Ob- servatoire, 1880. 8vo. Paris 1881. The Observatory. Ponts et Chaussées. Service Hydrométrique du Bassin de la Seine. Observations sur les Cours d’Hau et la Pluie, 1879. Ato. 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London 1881. Logarithms of the Values of all Vulgar Fractions. 8vo. London 1881. Ona Syste- matic Interruption in the Order of Numerical Values of Vulgar Fractions when arranged in a Series of Consecutive Magnitudes. 8vo. [London | 1881. ; The Author. Ball (R. 8.), F.R.S. Extension of the Theory of Screws to the Dynamics of any Material System. 4to. Dublin 1881. The Author. Brodie (Rev. P. B.) The Origin and Use of Mineral Phosphates as a Manure. 8vo. Warwick [1&80]. On Fossiliferous Pebbles in the Drift in Warwickshire. 8vo. [London] 1881. The Author. Buchanan (George) LHlectricity in Surgery. 8vo. Glasgow 1881. The Author. Burmeister (H.) Atlas de la Description Physique de la République Argentine. Premisre Section. Vues Pittoresques. folio. Buenos Aires 1881. The Author. Carruthers (Rev. G. T.) An Attempt to prove Newton’s Law of Attraction for a Resisting Medium. 8vo. Moorkee 1881. The Author. Fayrer (Sir Joseph), F.R.S. Rainfall and Climate in India. 8vo. London [1881 }. The Author. Fleming (S.) The Adoption of a Prime Meridian to be common to all Nations. 8vo. Lendon 1881. The Author. Francois de Chaumont (Ff. 8. B.), F.R.S. Introductory Lecture at Opening of 43rd Session of Army Medical School. 8vo. London 1881. The Author. Greenhill (A. G.) On the Motion of a Projectile in a Resisting Medium. 8vo. Woolwich 1881. The Author. Harrison (William H.) The Founding of the British Association. 12mo. London 1881. The Author. Jones (T'. Rupert), F.R.S. On the Geology and Physical Features of the Bagshot District. 8vo. Notes on some Paleozoic Bi-valved Entomostraca. 8vo. [London 1881]. Some Cambrian and Silu- rian Leperditiz and Primitiez. 8vo. [ London 1881 ]. The Author. Newcome (Frederick N.) Plan to Liquidate the National Debt with less than the Cost of Interest. 8vo. London [1881]. : The Author. R2 234 DerG. Ebi: Paterson (James) Notes on the lithology of Gas Coals. 8vo. War- rington 1881. The Author. Reade (T. Mellard) Notes on the Southern Drift of England and Wales. 8vo. Liverpool 1881. The Author. Siemens (C. W.), F.R.S. Science and Industry. 8vo. London 1881. The Author. Winn (J. M.) Materialism at the International Medical Coneress. 8vo. London. The Author. A Photograph of Colonel Tennant, R.H., F.R.S. “On Trichophyton tonsurans (the Fungus of Ringworm).” By Grorce Tun, M.D. Communicated by Professor HuxuEy, Sec. -R.S. Received February 19) 166i) ead March 3 [Puate 2.] The disease of the scalp popularly known in England as ringworm is described in medical works under the names herpes tonsurans and tinea tonsurans. When it occurs on the skin of the body it is known as tinea circinata and also as herpes tonsurans. The disease is widely spread in the human subject, exists in all climates, and also occurs in the horse, ox, and dog. It can be communicated from these animals to each other and to man. It was shown almost simultaneously by Gruby,* in France, and by Malmsten,f in Sweden, that the disease is due to the growth in the hairs and in the horny layers of the epidermis of a fungus which was named by Malmsten Trichophyton tonsurans. The statements of Malm- sten and Kiuchenmeistert that the parasite 1s found only amongst the cells which have undergone the horny change, that is to say, in the hair-shaft, between the hair-shaft and the internal root-sheath, and in the horny layer of the epidermis, have been recently confirmed by the evidence of sections made through the affected skin in the horse§ and in man. The parasite is not found amongst the living cells of the epidermis. * “Comptes Rendus,” &c., 1844, vol. xvii, p. 583. (Vide “ Végétaux Para- sites.” Par Ch. Robin. Page 417.) + ‘ Miiller’s Archiv,” 1848. (Swedish original, Trichophyton tonsurans, Harska- rande Mogel. Stockholm. 1845.) {~ Sydenham Society’s translation. ‘‘On Animal and Vegetable Parasites of the Ayaan Body,” vol. ii, p. 141. § Wide a paper by the author, “On the Condition of the Skin in tinea tonsu- rans,” in the 61st volume, and Wobten by Dr. Frederick Taylor in the 62nd volume, of the “ Transactions of the Royal Medical and Chirurgical Society.” On Trichophyton tonsurans (the Fungus of Ringworm). 235 The fungus, as at present known, consists of a mycelium and spores, and very little has been determined regarding its nature. Attempts that have been made to cultivate it artificially have led to contra- dictory conclusions. Lowe, in 1850,* was induced to believe that Trichophyton tonswrans is a spore formation of the fungus of favus—a specifically distinct parasitic disease of the skin—and that both are forms of Aspergillus. Neumann,f on the other hand, whilst believing that his cultivation experiments showed that herpes tonsurans and favus are produced by the same fungus, traced it in both diseases to Penicillium glaucum. Dr. Atkinson,{ again, was led by his cultivations to believe that the fungus belongs to the Mucors, and is probably Mucor mucedo. The reason why the botanical relations of the parasite to the common fungi have been so difficult to determine has been stated by De Bary. “If,” he remarks,§ speaking of the vegetable parasites of the skin, ‘‘ the parasites, when removed from the bodies of their hosts, are cultivated in water, sugar solution, &c., the vegetation of their spores is then observed, and. after a short time there appears in the fluids the universally wide-spread fungi, e.g., Penicillium glaucum, Aspergillus glaucus, or Torula. The latter and the mycelium of Peni- cullium resemble more or less the spores and mycelium of the parasites in question, and, being found in immediate contact with them, it seems as if they had been developed from them in the artificial medium.” Kobner,|| who endeavoured to solve some of the problems connected with the development of the parasite by clinical experiments, found that Trichophyton tonsurans, when inoculated on the skin, produced only herpes tonsurans, and that he could not produce this disease by inoculation with Penicillium glaucum. A strong reason exists, independently of experimental results, for believing that trichophyton is not a form of the common fungi. The facility with which. ringworm is communicated from one child to another by contact, or by interchange of caps, shows that the fungus takes root easily on the scaip, whilst, as many a country medical prac- titioner can testify, bareheaded children may be exposed indefinitely to contact with all the spores with which the atmosphere is pregnant without a single instance of the disease being produced. In endeavouring to cultivate Trichophyton tonsurans artificially, it was clear to me that one of the chief ditiiculties to be overcome was to * “ Botanical Transactions.” Edinburgh. 1850. + “ Lehrbuch der Hautkrankheiten.’’ 2nd edition. t “On the Botanical Relations of the Trichophyton tonsurans.” “ New York Medical Journal,’’ December, 1878. § Hofmeister’s “ Handbuch der Physiologischen Botanik,” Band 2, Abth. 1, p. 224. || ‘“‘ Klinische und Experimentelle Mittheilungen.” Erlangen. 1864. 236 Dr. Go Thin, avoid confusing accidental growths of common fungi with the spores and mycelium of the parasite. The size of the spores and mycelium is not to be relied on for this purpose, but their arrangement in an affected hair offers facilities for ascertaining whether in any given case trichophyton has developed. When a hair is extensively affected with rmgworm fungus, the root for a considerable extent is loaded with spores in all its thickness, and along its free borders the spores on the extreme edge can be seen under the microscope with perfect distinctness. It was thus evident to me that if there were observed at an early stage of the culti- vation a growth of those spores in the sides of the hairs which from their position could be recognised as rmgworm spores, the fallacy of deception by admixture of adventitious fungi would so far be avoided. At an early stage of my investigations, Mr. Banham, of the Brown Institution, showed me a preparation in which ringworm spores had in considerable numbers pushed out a tubular projection, by which their length had become at least double their breadth, and which was evidently the beginning of growth. This growth had taken place in a prepared cell in a drop of aqueous humour, but Mr. Banham informed me that he had not succeeded in getting the cultivation to go farther. The first attempts I made at cultivation were with ringworm hairs, which had been kept in my house for varying periods, having been put aside for the purpose of the investigation; but, after a series of negative results, I confined myself entirely to hairs freshly extracted from the heads of children affected with ringworm. These were usually put in the different solutions with which I experimented within periods varying from a quarter of an hour to two hours. When these ringworm hairs are placed in contact with fluids at a high tem- perature (92° to 98° F.), the spores soon show an outer surface or capsule, containing a spherical mass within it. This seems to be to a great extent independent of the nature of the fluid, and it is very apt to be mistaken for the first beginning of growth. When growth does not take place the appearance remains stationary. A variety of solu- tions were tried without result. These were used at first in cells, the hair being laid on the inner surface of the cover-glass of the cell and a drop of the solution placed over it. The hair was sometimes covered with the drop and sometimes only moistened ; in the latter case a ring ot damp blotting-paper was placed in the bottom of the cell, to prevent evaporation. The cells were then placed in an incubator. The temperature within the incubator varied during the course of the experiments between 92° and 98° F., but was mostly from about 96° to 98°. As these negative results afford evidence that Trichophyton ton- surans and the fungi usually present in the atmosphere are essentially different, they are worthy of being recorded. On Trichophyton tonsurans (the Fungus of Ringworm). 237 Experiments. 1. With the following solution :— SodavePhosplxessavcssecen sas 1 grm. eAcrmmonear aster tereiea's «ss ceneicae ote 10; ANCES GlISIBIN, 6E nieb Glouoe Clee OU 1,000 cub. centims., which I found had been in use in cultivation experiments at the Brown Institution. Thirteen cells with ringworm hairs in contact with this solution were placed at different times in the incubator, viz., two for three days, three for four days, five for six days, two for nine days, and one for fourteen days. There was no growth of trichophyton in any of them. Some minute particles of bread, on which common mould had been sprinkled, were placed in a drop of the same fluid in a cell, and placed in the incubator. Long mycelial threads grew on the under surface of the cover-glass. Again, a piece of bread slightly mouldy at some points was soaked in the same fluid, and with ringworm hairs placed on it, was put into a bottle, and the bottle placed in the incubator. The roots of the hairs were found entwined with a rich mycelial growth of fungi, considerably larger than the fungus of ringworm, but the spores of trichophyton could be seen after preparation and maceration in potash to be undeveloped. 2. A fluid (known, I believe, as Cohn’s fluid) with the following ; composition :— Magnesium Sulphate.......... 1 grm. Potassimml Nitrate). 235... a... I eraane Calcium Phosphate .......... 0:2 orm. Wiscilled: Water 2.0.2 i460... 500 cub. centims. One per cent. ammonium tartrate to be added before use. Two cells charged with ringworm hairs and the above fluid were placed at different times in the incubator, one for two and the other for eight days. The fungus grew in neither. Two hairs containing spores were floated on the surface of the fluid in a test-glass, and placed in the incubator for four days. There was no growth. Other ringworm hairs, placed in a small tube, were sunk at the bottom of the same test-glass. There was again no growth. Ringworm hairs were placed on bread soaked in the fluid, the bread being then put in a bottle and placed in the incubator for four days. The hairs were found enveloped in aspergillus. Trichophyton spores had not grown; being found after maceration to be in the same condition as in a diseased hair freshly extracted from a ringworm patch. 238 Dr. G. Thin. 3. Miik.—The milk used had been purified by boiling in a water bath, and had been kept pure in purified glasses, according to the method described by Mr. hister.* The results of the experiments were negative, but are in other respects interesting. A hair from a patch of ringworm was placed on the surface of milk, in a glass otherwise kept pure and set aside at the room temperature on the 16th March. It was taken out on the 27th, a fungus growth having been visible to the naked eye for several days. The root of the hair was found enveloped in Penicillium glaucum. When the hair had been macerated in a solution of potash it was seen that it had been healthy, and it contained no ringworm spores. Two hairs, which turned out to be ringworm hairs, were kept on the surface of milk for eighteen days. ‘There was large development of fungus, but I could obtain no evidence that it had any connexion with the ringworm spores. A supposed ringworm hair, after being on the surface of milk for three days in the incubator was found enveloped in fungus, but maceration in potash showed that there was no trichophyton in the hair. A ring worm hair in a tube at the bottom of the milk glass in two days in the incubator had developed nothing. Two ig tea showed that even with milk the development of a fungus does not necessarily follow when protected pure gles are used. A supposed ringworm hair was placed on pure milk in a protected glass in the incubator for three days. No fungus of any kind grew, and maceration of the hair in potash showed that the hair was not affected with trichophyton. Another supposed ringworm hair, but which subsequent examination showed to contain no spores, was placed in pure milk in a protected glass for thirteen days without any fungus developing. My attempts to grow trichophyton in milk thus failed. In connexion with Mr. Lister’s experiments on the lactic fermenta- tion, it may be worthy of remark that the glasses used were all charged with pure milk by the method he has deseribed and that the milk remained unchanged until they were used for these experiments. With the introduction of the hairs bacteria were necessarily also introduced, but the glasses being immediately protected, no other bacteria than those adhering to the hairs were present. The hairs, after they were extracted from the patients’ heads, had been kept in paper until they were brought in contact with the milk. Various although usually very slight changes took place in the appearance ot the milk, but in none of the glasses did the common lactic fermenta- * “On the Lactic Fermentation.” ‘Transactions of the Pathological Society of London,” vol. xxix. On Trichophyton tonsurans (the Mungus of Ringworm). 239 tion occur, so far as a curdled condition is evidence of that change. A thin stratum of clear fluid in one case appeared on the surface of the milk, but to a much less extent than in ordinary curdling. A. Aqueous Humour.—Two experiments only were made with aqueous humour, the cells charged with it being placed inthe incubator. In one after five days there was no growth of the ringworm spores; in the other, during forty-eight hours, a bulging had taken place from some of the spores, evidently the beginning of growth. On account of the greater convenience in getting large quantities of fluid vitreous humour was used instead of aqueous humour in subsequent experi- ments. 5. Tap Water.—A ringworm hair, moistened with tap water, was placed in the incubator. During nine days there was no growth. 6. Carrot Infusion—One cell was prepared with carrot infusion. During four days no growth took place. 7. Salé Solution.—Strength 0°75 per cent.—A cell thus prepared was placed in the incubator for five days: no growth. Hairs were floated on the solution in a glass in the incubator for six days without growth of trichophyton spores. 8. Turnip Infusion.—Bread, soaked in turnip infusion, was placed in a box and ringworm hairs placed on the bread at different points. The box was covered and placed on the top of the incubator, where the heat was less than inside. After four days the bread was found covered with fungi. The ringworm hairs were picked out, macerated in potash, and examined. All the spores were round, and there was no appearance on the sides of the hairs of bulging or early mycelium formation. Ringworm hairs were floated on pure turnip infusion in protected elasses, and placed in the incubator for five days. They were then examined. The spores observed in the hairs were all round, and there was no growth from the sides. Another experiment of the same kind in which the hairs were examined after four days, showed a like negative result. In another similar experiment the hairs were found after eight days imbedded in fungus, Penicillium glaucum. ‘The hairs, when examined, were seen to be full of spores, which had not sprouted from the sides in the least degree; those which were lying on the extreme edge of the hair being found round and unchanged. In two cells charged with diseased hairs, minute morsels of bread and turnip infusion, and placed in the incubator, no rmgworm growth took place during four days; and another experiment, in which the hairs were floated on the infusion and kept in the incubator for seven days, also showed a negative result. The attempts to grow trichophyton in turnip infusion thus all failed. 240 | Dr. G. Thin. 9. Hag Albumen.—Seven attempted cultivations with ege albumen in the incubator, and one at room temperature, also one with acid albumen in the incubator, conducted in the same manner as those already described, all failed. 10. Hog Albumen and Potash.—Four attempted cultivations with albumen, to which a small proportion of solution of potash had been added, also failed. In two of them the hairs were floated on the surface of the fluid in glasses.placed in the incubator; in the other two the hairs had been sunk to the bottom. ll. Vitreous Humour and Potash—Three cultivation experiments with vitreous humour and potash, similarly conducted, in one of which the ringworm hairs were floated on the top, whilst in the other two they were sunk to the bottom, also failed. 12. Vitreous Humour.—As vitreous humour is the only fluid with which I have succeeded in culuvating trichophyton, and as, even with this fluid, special conditions are necessary, it is desirable to describe the experiments and mode of procedure in detail. It will be convenient to divide them into— 1. Cultivation in cells at incubator temperature; no growth taking place. No. of days No. of cells. in incubator. Remarks, | lMtath Nyacees ys se 2 SRE URES ors A Aap ec Meet 4) | i easing 6 SO igen een Econ 7 OL ee 8 IN da Mii lesa a kL 3) 1 aE i alihd Art atdta 10 Aas laluminge ulanetnas 11 Die EMA Ase 12 Se ker ree 56 No. of days in incubator — not noted. 32 The cells were, during these periods, examined daily, and imme- diately afterwards put back again into the incubator. Those regard- ing which it is remarked that the time was not noted are the cells which were used in the earlier experiments. They were kept a long time, and frequently examined, the date on which they were finally taken out not being noted. In the earlier of these experiments, the hairs used had been extracted for some time from the patients, and had been kept folded in paper. This may possibly have had something to do with the negative results. On Trichophyton tonsurans (the Fungus of Ringworm). 241 In a large proportion of them, however, freshly extracted hairs were used. 2. Cultivation in cells at room temperature. No growth took place. No. of celis. No. of days. Wes in ane eee a 2 IO a on enAmeg es 10 3. About the time when the experiments referred to in the above tables were ended, it occurred to me that the reason why the spores did not grow was because the hairs were submerged in the fluid. Acting on this idea, I moistened the under side of the cover-glass of the cell, taking care that the roots of the hairs used were not covered with the fluid. For the first time I obtained evidences of undoubted growth. Theconvenience of the cell for such experiments was now well shown, as I was able to observe the earliest evidence of mycelial growth from the spores on the sides of the hairs without disturbing the preparation, which could be put back again into the incubator without any part of it being moved. In these instances there was no possibility of a mistake being made by confounding adven- titious fungi with trichophyton. The spores of the latter could be examined im situ through the cover-glass, and as germination took place the spores could be seen elongating into a mycelium from their original position on the edge of the hair. In three cells prepared in this way trichophyton grew. The first appearance of elongation in the spores was observed after the preparation had been a few hours in the incubator, the hairs having been transferred from the head of the child to the incubator after a very short interval. During the two following days the growth went on to the formation of mycelium. The mycelium, however, ceased to grow after having attained a very moderate length; spore formation soon beginning to take place. (Similar cells prepared in the same way with Cohn’s fluid and with hairs from the same patch showed no signs of growth.) The disadvantages associated with this mode of cultivation were found to be the following :— It was difficult to hit on the right quantity of fluid. If there was too much the spores did not grow, and if there was too little they did not grow, and when the quantity happened to he sufficient to encourage germination it was not enough to maintain growth after the mycelium had attained a comparatively limited length. This difficulty was got over in the following way :— 4, When the hair was laid gently on the surface of vitreous humour in a test-glass, it did not sink, and by simply floating the hairs I was able to secure the requisite conditions of moisture without immer- sion. 242 DreGse vim The vitreous humour used had been prepared in the manner described in a paper on Bacterium fetidum (“‘ Proc. Roy. Soc.,” No. 205, 1880), and the hairs were laid on this pure fluid, and placed in the incubator in pretected glasses. The only source of contamination was the organisms that were introduced with the hair. Experiment showed that whilst in all cases there was a free development of bacteria, the development of adventitious fungi was frequently avoided. The following table gives the results of twelve cultivations made by this method :— Cultivations on the surface of Vitreous Humour in Test-classes in the Incubator. No. of Growth of No. of days R : as 2 emarks. experiment. trichophyton. | in incubator. eras in| | i tie Sei 1 No. 6 Adventitious fungi grew. 2 No. 6 3 BYies: 3 4 Wes: 2 5 Yes. 2 6 Yes. a 7 No. 8 8 Wes: 8 Slight growth. 9 ies: 3 10 Yes. 7 11 Yes. 3 Slight growth of trichophy- ton: much adventitious fungi. 12 No 6 Growth of aspergillus. \ One experiment was made to ascertain whether ine could be cultivated at ordinary temperatures. On the 20th April several ringworm hairs were placed on the surface of vitreous humour in a protected flask, which was put aside and kept at the ordinary temperature of the work-room. On the ord May the hairs were examined. Trichophyton was found to be growing from their edges, but the growth was not so luxuriant as it was usually found to be after two days’ cultivation when the test- glass was kept in the high temperature of the incubator. In one recorded experiment the hairs extracted from a ringworm patch did not happen to contain trichophyton. After three days’ cultivation in the incubator no fungus of any kind had grown. Several other similar experiments, which were not accurately noted, showed that if a hair which did not contain trichophyton was not much exposed before being placed on the vitreous humour, the On Trichophyton tonsurans (the Fungus of Ringworm). 243 elass containing it might be placed for several days in the incubator without the development of adventitious fungi. It follows from the facts recorded in this table that although the method may be relied on for the cultivation of rmgworm fungus, it cannot be considered certain. I am not able to account for the failures recorded in experiments 1, 2, 7, and 12, but they did not surprise me. Simultaneously with the experiments on trichophyton I had made a number of cultiva- tions of the common fungi found in our houses, and had learned how delicate are the conditions of growth to which they are all subject. One of the most important of these conditions is the requisite degree of moisture, which must be neither in deficiency nor excess. The failures recorded in these experiments may possibly have been due to the hairs having become too much immersed, or the spores themselves may have been incapable of germination from changes effected in ihem by inflammatory exudation around the hair follicles before they were extracted. The growth observed consisted in a development of mycelium from spores, and in the formation of spores within the mycelium, as is por- trayed in the drawings in the plate. No organs of fructification were observed. Two experiments were made with ringworm hairs which had been sunk in water. In one case the length of time of the immersion is not noted; in the other the hairs were immersed six days. In neither ease did trichophyton grow when an attempt at cultivation on vitreous humour was made. Considering the uncertainty of vitreous humour cultivations, these two experiments have only a very limited value, but, so far as they go, they support the inferences which follow from other experiments made in the same direction. The hairs in which trichophyton grew were all freshly extracted, but one expe- riment was made with two hairs, kept dry in a box for thirteen days. The spores were very numerous in these hairs; only one appearance of growing mycelium was observed, a spore having sprouted on the side of the hair. There were, on the other hand, some similar experiments with negative results. Four cultivations were tried with hairs which had been kept eleven days, and three with hairs which had been kept twenty-two days; in all of them the spores remained unchanged. The value of these experiments is, on account of the uncertainty of the cultivations, not very great, but it may be well to put them on record. The same remark applies to experiments made with hairs taken from patches which were under treatment. The vitality of trichophyton is destroyed as a result of many varieties of treatment, the essential feature in all of which is that they produce inflammation of the skin. As soon, therefore, as I had determined that the spores in untreated hairs could be grown in a fairly large proportion of the 944 Des Go Thin: experiments made, I undertook cultivations with hairs extracted from patches which were under active treatment for the cure of the disease. With one exception, and in that one the growth was open to doubt, all these cultivations failed. Nineteen such cultivations were attempted, in two the hairs being on the vitreous humour in the incu- bator for two days, in eight for three days, in six for four days, and in three for five days. The treatment had consisted in rubbing into the scalp, on the affected places, sulphur ointment and mercurial SHAE of various kinds and strengths. The failure. to cultivate trichophyton in these cases did not coin- cide in point of time with the cure of the disease, for in many of them the malady followed its somewhat tedious course for a considerable time after the dates of the experiments. The fact that 1 had been unable to produce growth of tricho- phyton in cells, so long as the spores were completely immersed in vitreous humour, led me to make the following experiments. Ring- worm hairs were extracted froma patch of untreated rmgworm. Some of them were inserted into a small glass tube, which was placed at the bottom of the test-glass, and others were floated on the surface of the fluid in the usual way. After two days the hairs were examined. There was an abundant growth of mycelium around the roots of those hairs which were on the surface. The mycelium was of the size of that of ringworm, and in some of it black pigment had been depo- sited. No spores had formed. I satisfied myself at the time that it had developed from the ringworm spores. On macerating the hairs the mycelial growth of trichophyton inside the hair-shafts was also found pigmented. In the hairs deposited in the tube at the bottom of the test-glass no growth had taken place, although on maceration they were found to contain mycelium and spores of trichophyton, both containing black pigment.* In another instance, in which the experiment was conducted in pre- cisely the same conditions, an examination was made after the test- glass had been six days in the incubator. There was free growth of trichophyton in the hairs which had been floating on the surface of the fluid, whilst there was no growth in the hairs which were in the tube at the bottom of the glass. In these two experiments all the hairs, both those on the surface and those at the bottom, contained trichophyton, and in each experiment both the surface and the sunk hairs were taken at the same time from the same patient, every condition being alike, except that in the one * This patient is not the only one in whose diseased hairs the rmgworm fungus was pigmented. I have found the same pecularity in other cases, and in the effected hairs from a patch of this disease, in a black horse, I found pigmented my- Celium and spores very common. On Trichophyton tonsurans (the Fungus of Ringworm). 245 case the hairs were on the surface of the fluid, and in the other they were completely immersed in it. It seems impossible to resist the conclusion from these and from the earlier cell experiments that trichophyton cannot grow when im- mersed in vitreous humour, whilst it grows freely when only moist- ened. by it. These experiments further suggest the view that inflammation cures ringworm by drowning the fungus. The data supplied by recent pathological researches show that serous effusion from the blood- vessels is the invariable concomitant of inflammatory action, however it is produced. When a persistent inflammatory congestion is kept up by irritants around the hair follicles, it of necessity follows that the serous effusion should make its way through the root-sheaths, whilst the inner root-sheath, and the cuticle of the hair are more or less broken up by the growth of the fungus. It is a fair inference from the experiments described in this paper that the capacity for growth in trichophyton must be destroyed by the resulting immersion in serum. Clinically and as a matter of fact, we know that this is just what takes place, and the only reason why ring- worm is such a tedious disease under treatment is that the same amount of irritation by external agents does not produce the same amount of congestion in any two patients, and that a careful practi- tioner will always hesitate to induce such an intensity of inflammation as might injure the health of the patient or produce partial baldness by destruction of the hair follicles. Trichophyton tonsurans, although it grows in the epidermis of children and adults alike, and thrives in the hairs of the scalp in children, cannot, as a rule to which there is hardly any exception, live in the hairs and follicles of the scalp of adults. ‘The explanation of this peculiarity will probably be found in the anatomical relations of the inner root-sheath and the hair, and I suggest as an hypothesis that the fungus does not penetrate between these structures in the adult because it does not find there sufficient moisture for its development. Preparations showing the mycelium well, with the process of spore formation as it takes place within the hair-shaft, do not appear to have been often portrayed, if we may judge by the figures in ordinary medical works, most of the drawings which are found in text-books of medicine representing it imperfectly. I found that hairs which had been macerated for several days in vitreous humour afforded excellent specimens for observation. Good preparations of trichophyton, showing the different stages of development, are easily obtained by ordinary methods from scrapings of the epidermis in ringworm of the skin of the body, and an excellent representation of the appearances then seen is given in Cornil and Ranvier’s ‘‘ Manuel d’Histologie Pathologique,” p. 1221. 246 Dr-G. Dm: The main conclusions regarding Trichophyton tonsurans which are warranted by the experiments recorded in this paper are that :— 1. It is not one of the common fungi. 2. It can be cultivated artificially when moistened by vitreous humour. 3. When covered by vitreous humour it does not grow. The second of these formulated statements suggests whether the inability of the fungus to grow in the hairs of the scalp in adults may not be due to the firmer texture of the root-sheaths, and the consequent comparative absence of moisture between the inner root-sheath and the hair. The third explains why the fungus may be destroyed by pro- voking inflammation of the scalp. DESCRIPTION OF PLATE 2. Figure 1. Cultivation ina cell. (Two days in the incubator.) x 750. Figure 2. Cultivation on the surface of vitreous humour in a test-glass, showing the first appearance of spore-formation in the mycelium. x 600. Figure 3. Growth on the surface of vitreous humour in a test-glass, showing an early stage of spore-formation. x 880. Figure 4. Spores germinating. Drawn (without the camera) from a preparation in a cell the same day in which it had been placed in the incubator. Figure 5. Two days’ growth im a cell. x 750. Figure 6. Two days’ growth in a cell. x 750. Figure 7.* A hair from a cultivation on the surface of vitreous humour in a test- glass. A mass of germinating and sprouting spores on a portion of the internal root-sheath which was attached to the hair is seen at the side of the hair-shaft. Buds and mycelium are sprouting from the sides of the hair. (In order to reduce the size of the drawing the centre of the hair-shaft has been left out.) x 490. * No attempt has been made to represent the fungus growth on the upper sur- face of the hair, as it lies in the preparation. The outlines were too much obscured by the thickness of the hair to enable this to be accurately done with the camera. Hest Newianr. & Co laze. On Bacterium decalvans. 247 “On Bacterium decalvans: an Organism associated with the De- struction of the Hair in Alopecia areata.” By GroRGE THIN, M.D. Communicated by Professor HUXLEY, Sec. R.S. Received February 19, 1881. Read March 3. [PLATE 3. | Although Gruby,* in the year 1843, announced that the affection of the hairy scalp known as alopecia areata (area celsi) is caused by a fungus, the parasitic theory of the disease has met with comparatively little support. If the patients on whom Gruby made his observations really suffered from this disease and not from ringworm, which in some of its forms is apt to be mistaken for it, this uncertainty is very remarkable. The fungus, if it exists, should not be difficult of observation, since it is described in his paper as consisting of a sheath of mycelium and spores which accompanies the hair to a distance of 1—8 millims. from the skin. Few competent observers have, how- ever, been able to find a fungus in this disease, and Dr. Michelson, of Konigsberg, in an able historical sketch in a recent number of “ Vir- chow’s Archiv,’’+ quotes with approval'a statement by Pincus,t who avers that up to the year 1869 none of the observations which are relied on as confirming Gruby’s observations will stand criticism. The fungus has been sought for chiefly by dermatologists, and in Hebra’s text-book of ‘“‘Skin Diseases,’§ a work of recognised standing, v. Barensprung, Hebra, Wilson, Neumann, Boeck, Duhring, Scheren- berg, and Kaposi are cited as having been unable to find it. The parasitic theory originated by Gruby was noticed less and less by authorities, the disappearance of the hair in patches from a pale un- inflamed skin being attributed to a “ tropho-neurosis.” Latterly, the question of parasitism has been again raised. Malassez|| stated in a paper published in 1874 that he had found a fungus, not in the hairs, but on the surface of the epidermis of the diseased parts. There was no mycelium found, but only spores, of which he described three types :— 1. Double-contoured spores, sometimes with a bud (bourgeon), 4—du in diameter ; 2. Smaller spores, 2—2°5u large, single-contoured, some of these also with a bud ; 3. Very small, under 2 sporules, single-contoured and without buds. * “Comptes Rendus,” 1843, xvii, p. 301. jaiVols ixxx, p. 296. t “ Ueber Herpes tonsurans u. Area Celsi.” “ Deutsche Klinik,” vol. xxi. § “ Lehrbuch der Hautkrankheiten,” vol. ii, p. 150. || “‘ Archives de Physiologie Norm. et Patholog.,” 1874. VOL. XXXIII. 8 248 DeeGe Thm. Hichhorst* states that in nine cases he found spores on the diseased hairs once, between the shaft and root sheaths. There was no myce- lium, and the spores were about the size of those of the Microsporon | furfur. The descriptions given by Gruby, Malassez, and Hichhorst of his solitary case differ from each other; Gruby describing a fungus with mycelium which ensheathes the hair shaft, Malassez single spores of various sizes scattered over the epidermis, and Hichhorst large spores between the hair shaft and root sheaths. A hypothesis ef another kind has been put forward by Buchner.+ Considering that the disappearance of the hair in ever-widening circles which bear no relation to the distribution of blood-vessels or nerves, without any evident cause, is best explained by the theory of parasitism, but yet acknowledging the failure of the attempts that have been made to discover the parasite, this observer asks whether the parasite may not be a bacterium, which on account of its smallness and position in the hair cannot be brought under observation. In support of this hypothesis he instances an experiment which he made. In a case of the disease he extracted hairs from the affected patch with heated forceps (so as to exclude contamination to the greatest possible extent), and placed them in a cultivating fluid. He reasoned that if there are bacteria in the hairs they will be in greater number than the bacteria introduced accidentally with the hairs, and that in the first hours of cultivation they would greatly outnumber these latter. Accordingly, he found in eight successive cultivations a bacterium which he describes as a small refractive sharply contoured particle (Kérnchen), scarcely 0-001 millim. in diameter, with two very fine and short thread-like processes projecting from opposite poles. He remarks that this may not necessarily be the form which the presumed bacterium has in the hair, as the effect of cultivation is sometimes to alter the forms of bacteria. The observations which are recorded in the following paper were preceded by desultory studies of hairs extracted from patients suffer- ing from this disease during the five years preceding 1880, of which no notes were taken, my attention having been directed to the subject after the appearance of Malassez’s paper in 1874. In none of the hairs, however, which I examined did I discover a fungus. The hairs which I did not have time to examine were put away for future study, carefully folded in paper. In examining one of the hairs which had been kept for some time, I observed flakes of a filmy substance fall away from the hair, and imbedded in this substance there were what seemed to me to be great numbers of micrococci. From that time when examining hairs from the margin of patches * “ Virchow’s Archiv,”’ vol. lxxviil. + “ Virchow’s Archiv,” vol. lxxiy. On Bacterium decalvans. 94g of this disease I always looked for evidences of the presence of bacteria. The difficulty of distinguishing in a fluid minute granules from micrococci or from the spore forms of rod bacteria, 1s so great, that it was only when the characteristic appearances of elongating spheroids or small rod-shaped bodies containing spheroidal ele- ments, arranged linearly, or rod bacteria were observed, that the evidence of the presence of organisms was deemed conclusive. ‘These were, however, observed sufficiently often to satisfy me that their presence was probably more than accidental, and to induce me to submit the affected hairs to various processes with the view of enabling the contents of the hair shaft to be better observed. During the year 1880 six cases were specially utilised for this purpose, and, as in all these cases, a considerable number of hairs, in several of them a large number, were examined and submitted to methods of examination eminently fitted to display a fungus, if such were present, it may be useful to state in further confirmation of the opinions generally entertained, that in none of them any more than in those previously observed, was any fungus discovered.* All these six cases were unmistakable examples of alopecia areata. Hvidence that this was so would be out of place in this paper, but will be given in due time in a professional journal in connexion with a description of the treatment under which the disease was in all of them at once arrested.t The treatment referred to was based on the evidence which, by this time I believed I had obtained, that the progress of the disease was due to the development of a bacterium. In utilising these cases for the demonstration of an organism, my object was not so much to observe bacteria in fluids in which the hairs were examined, as to endeavour to find some method by which their presence could be shown in the substance of the hair. In five of the six cases I satisfied myself that this had been done. This demonstra- tion is attended with great difficulty. In a comparatively sound hair it is very difficult to bring minute objects like bacteria under observa- tion, and in hairs which are considerably affected the shaft is found, when prepared for examination, to be so full of pigment and other granules that it becomes very difficult to distinguish organisms amongst them, presuming these to be present. The methods employed were the following :— * The extent to which these investigations have been carried, more especially as regards the number of hairs examined in some of the cases, leads me to believe that those authors who have described a fungus in alopecia areata made a mistaken diagnosis, and that their cases were examples of ringworm in which the growth of the trichophyton had produced comparatively little reaction in the skin. + As I am familiar with the disease, for the purposes of this paper my statement as regards the diagnosis may be considered sufficient. 250 Dr. G. Thin. 1. The hairs when extracted were placed for a short interval in potash solution (the strength used varied from 5 to 20 per cent.) ; they were then washed in distilled water, and passed successively through absolute alcohol and ether. After being thoroughly subjected to the action of ether they were again placed successively in alcohol and distilled water, and were then finally mounted for examination in diluted Goadby’s solution.* The object of these manceuvres was to make the hair transparent, free it from oily particles, and finally mount it in a medium suitable for the detection and preservation of any organisms which it might contain. The method was not perfectly nor always successful, but in some instances it sufficed to show objects within the cuticle of the hair, which I believe it is justifiable to consider as bacteria. 2. The extracted hairs were at once examined in the Goadby’s solution. 3. The hairs were placed successively in absolute alcohol, oil of cloves, and dammar varnish, in which they were examined. 4, Hairs kept for future examination in Goadby’s solution, and in a 5 per cent. solution of carbolic acid were at convenient times, after being soaked for a little while in distilled water, subjected to the alcohol, oil of cloves, and dammar process. In all cases precautions were taken to prevent the development of organisms after the hairs were extracted. Attempts to show the presence of bacteria in the hairs by staining with methylaniline were defeated by the intensity with which the hair itself was staimed with this dye. The result of the examinations of a large number of hairs prepared by these methods has been to satisfy me that minute objects can be de- tected in them similar in size and form to those which I had recognised as organisms on the borders of freshly-extracted hairs, and preparations were obtained in which these objects were found in positions, and so arranged as to show that they were distinct from the rows and agegre- gations of minute granules which are found in healthy hairs. The objects referred to were seen either as round or as elongated rounded bodies, and resembled in shape and in their refractive qualities the elements which I have described as cocci in a paper on Bacterium fetidum (“ Proc. Roy. Soc.,” No. 205, 1880). In the preparations put up in dammar varnish these bodies were not liable to be mistaken for oily particles or crystals, which were not present in the hairs. In the preparations put up in Goadby’s solution, in spite of the care which had been taken to soak the hairs in ether, oily * The following is the formula :—Bay salt, 12 ounces; burnt alum, 6 ounces ; corrosive sublimate, 15 grains; water, 1 gallon. Dissolve and filter. I have found it an excellent medium for mounting. On Bacterium decalvans. PGS | particles were present to such an extent as frequently to make accu- rate observations impossible. In some hairs, however, this mode of preparation had produced results which were most instructive. The effect of the potash and other treatment had been to get quit of the whole contents of the cuticle at some parts, the cuticle being then seen as a transparent membrane. At these parts the minute objects I have described were found clustered on the inner surface of the membrane. In all the hairs in which they were found, and in all the patients, these bodies were the same in size, and refracted light in the same way. They were found frequently in pairs, the long axis of each member of the pair forming a continuous line. Sometimes three of them were found end to end with an appearance of one continuous sheath for the three. These appearances are characteristic of bacteria in development. In seven cases in which a treatment was applied that was designed to arrest the development of organisms, and mechanically to prevent their being transported from one hair to the other, the disease at once ceased to spread. In one case, whilst the patches under treatment had been arrested, and new hairs were coming on them, two other patches had appeared unobserved on other parts of the head. The same treatment at once arrested the growth of these new patches. I have taken much pains to represent the size of these bodies by means of camera drawings, and I believe I have succeeded fairly well ; but I confess to have found it very difficult to get the exact size. As many measurements made of the same objects agreed with each other I believe the drawings may be taken as a guarantee, both of size and shape. In order further to ensure accuracy in this respect I obtained the kind assistance of Mr. Noble Smith, whose capacity as an accurate draughtsman in all that relates to microscopic objects is recognised and appreciated. Fig. 2 was prepared from a drawing by Mr. Smith. He determined the outlines of the hair, and drew a number of the objects (or organisms) to the size in which he saw them. The others were filled in to the scale determined by Mr. Smith. The magnifying power represented in the drawing was estimated by measuring the hair. ; Clusters of the organisms were also found in dammar preparations in which the hair was found split into shreds. These shreds were sometimes so thin that the objects which I am describing were seen with much distinctness. The order of development of the organisms, or the different'stages of their action in breaking up the hair shaft, I believe to be indi- cated by the appearances which I have figured in the drawings. In 252 Dr. G. Thin. fig. 1 there is represented what I believe to be an early stage, the earliest which I have observed. A cluster of bacteria is seen on the surface of the hair shaft, but under the cuticle of the hair, whilst on the side of the hair others are seen embedded in granular débris, probably remains of the inner root sheath. The shaft of the hair is unbroken. , In fig. 2 great numbers of bacteria are seen near the root of a hair. By regulation of the fine adjustment the position of the bacteria could be accurately made out. A considerable length of the root sheath had come away with the hair, completely investing it. The bacteria were found ina circular layer between the root sheath and the shaft of the hair. They had neither penetrated the root sheath nor the shaft. Fig. 4 indicates the position of the organisms as they are seen when the centre of the hair is brought into focus: the drawing being on too small a scale to show the individual bacteria their position has been shown by dark shading. In fig. 5 the dark shading shows the position of the bacteria when the lower surface of the hair is brought into focus. By comparing these three figures with each other, the arrangement of the bacteria becomes apparent. In fic. 6 part of a hair is represented in which the removal of the sub-. stance of the hair shaft has shown anumber of organisms disseminated over the inner surface of the cuticle. They were traced towards the thick unemptied part of the hair, in which they became lost in a thick erapular mass. In fig. 7 a hair is shown in which organisms were found immediately under the cuticle. I infer from all these appearances that the bacterium penetrates downwards between the internal root sheath and the shaft. Towards the root of the hair it penetrates the hair substance, and as 1t multi- ples it ascends upwards in the substance of the hair. The breaking up, loosening, and disappearance of the hair is to be attributed to the disorganisation of the hair substance by the growing organisms, for it — is impossible to suppose that a free development of bacteria could take place in the shaft of a hair without the substance being decomposed and its integrity destroyed. This is the inference which it seems to me follows naturally from the detection of organisms in the diseased hairs in alopecia areata. It might be alleged that it has not been shown that the composition of the hair is not altered by some supposed error of nutrition, and that bacteria find in these abnormal hairs a soil in which they can thrive. No such alleged nutritive change has ever been shown to exist, and I believe that the existence of an object of a definite size and form having the characteristic appearance of a bacterium, and now ascer- tained for a certain although a small number of cases, will afford to workers in similar fields strong presumptive evidence that its presence is the key to the mystery in which the disease has been shrouded. In ee ee (Co eet avis Vest New a) On Bacterium decalvans. 253 extracting hairs for examination I took them from a considerable breadth of margin, and as the proportion of the hairs examined which showed any change or evidence of organisms was small, it is probable that these are present only in a narrow zone, and that after a hair is once attacked development takes place rapidly and the hair soon falls. It may be well to divide the statements made in this paper into two heads; those which relate to ascertained facts, and those which relate to a theory of the causation of alopecia areata, which I believe is sustained by these facts :— 1. The facts are that minute bodies of definite and fixed shape and size are found in and on the hairs in alopecia areata. These bodies are distinct from the granular elements present in hairs, and are neither oily particles nor crystals. They are of the size and shape, and have the refractive qualities of bacteria. When present in small numbers on the shaft the hair is entire, whilst within some hairs much affected by the disease they were found in great numbers. 2. The theory is that these bodies are bacteria, and that the disappearance of the hair is due to a breaking up of the hair shaft by the multiplication in it of the organisms. As I believe it is desirable to give to definite objects like those which I have described a name which will mark their association with the theory I have founded on them, and as I am myself satisfied as to their nature, I suggest the term Bacterium decalvans as a convenient designation. . DESCRIPTION OF PLATE 3. Figure 1. Case of 8S. B. A small group of organisms on the shaft of the hair, under the cuticle. Others are seen (scattered in a granular mass which is adherent to the hair. ; (Camera drawing.) x 600. Figure 2. Case of I. F. Organisms between the root-sheath and the shaft of the hair near the root. (Drawn by Mr. Noble Smith.) x about 470. Figure 3. Organisms from the group shown in fig. 2, more highly magnified. (Camera drawing.) x 560. Figure 4. The hair shown in fig. 2, the focus being now in the axis of the hair. The position of the organisms is indicated by the dark shading. Figure 5, The hair shown in fig. 2 when the focus is carried down to the under surface, the position of the organisms being again indicated by the dark shading, Figure 6. Case of S.B. In a part of the hair from which the substance of the hair-shaft has disappeared and the cuticle left empty, organisms are seen lying on the internal surface of the cuticle. (Camera drawing.) x 880. Figure 7. Case of N.S. Organisms on the shaft and beneath the cuticle. (Camera drawing.) VOL. XXXIII, T 254 J.W. Dawson. LHrect Trees containing Reptilian | Jan. 12, January 12, 1882. THE PRESIDENT in the Chair. The Right Hon. Sir George William Wilshere Bramwell, and the Right Hon. Henry Fawcett, whose certificates had been suspended as required by the Statutes, were balloted for and elected Fellows of the Society. The Presents received were laid on the table, and thanks ordered for them. The following Papers were read :— I. «On the Results of Recent Explorations of Erect Trees containing Reptilian Remains in the Coal Formation of Nova Scotia.” By J. W. Dawson, C.M.G., LL.D., F.R.S., &e. Received October 11, 1881. (Abstract. ) The explorations referred to were carried on chiefly in the beds at Coal Mine Point, South Joggins, Nova Scotia; and their object was to make an exhaustive examination of the contents of erect trees found at that place and containing remains of Batrachians and other land animals. A detailed section is given of the beds containing the erect trees in question, with lists of their fossil remains. The most important part of the section is the following :— Sandstone with erect Calamite and Stigmaria TOOES 6 ane cI eee Tore eee coos hee ee 6 ft. 6 in Argillaceous sandstone, Ualamites, Stugmaria, and Alethoptenis © Wehiied -r8. oi 6 tovis -11o-1 -)202 eee dL geen oye Gray shale, with numerous fossil plants, and also Naiadites, Carbonia, and fish scales.......... OF, eee Black coaly shale, with similar fossils.......... 1 lee Coal, with impressions of Szgillaria bark ...... 0... = On the surface of the coal stand many erect Sigillaric, penetrating the beds above, and some of them nearly three feet in diameter at the base and nine feet in height. In the lower part of many of these erect trees there is a deposit of earthy matter, blackened with carbon and vegetable remains, and richly stored with bones of small reptiles, land snails, and millipedes. Detailed descriptions of the contents of these 1882.] Remains in the Coal Formation of Nova Scotia. 255 trees are given, and it is shown that on decay of the woody axis and inner bark they must have constituted open cylindrical cavities, in which small animals sheltered themselves, or into which they fell and remained imprisoned. These natural traps must have remained open for some time on a subaerial surface. In all twenty-five of these erect trees had been discovered and extracted, and the productive portions of them preserved and carefully examined. Of these, fifteen had proved more or less productive of animal remains. From one no less than twelve reptilian skeletons had been obtained. In a few instances, not only the bones, but portions of cuticle, ornamented with horny scales and spines, had been preserved. The Batrachians obtained were referred to twelve species in all. Of these two were represented so imperfectly that they could not be defi- nitely characterised. The remaining ten were referable to the two family groups of Microsauria and Labyrinthodontia. The Microsauria are characterised by somewhat narrow crania, smooth cranial bones, simple or non- plaited teeth, well-developed limbs and ribs, elongated biconcave vertebree, bony scales and plates on the abdomen, and horny scales, often ornate, on the back and sides. They show no traces of gills. The species belonging to this group are referred to the genera Hylonomus, Smilerpeton, Hylerpeton and Fritschia. The characters of these genera and of the several species - are given in detail and illustrated by drawings and photographs, including microscopic delineations of the teeth of all the species, with their internal structure and the microscopic structure of their bones, as well as representations of their cuticular ornamentation and armour. The Labyrinthodonts are represented by only two species of Den- drerpeton, which are also described and delineated. About half of the reptilian species described are new, and those previously described from fragmentary remains are now more fully characterised, and their parts more minutely examined. The invertebrate animals found are three species of land snails and five of myriapods, besides specimens supposed to represent new species of myriapods and insect larve, not yet fully examined, and which have been placed in the hands of Dr. Scudder, of Cambridge, U.S. The memoir, consisting in great part of condensed descriptions of the facts observed, does not admit of much abridgment, and cannot be rendered fully intelligible without the accompanying plans, sections, and drawings. It closes with the following general statement :— “The negative result that, under the exceptionally favourable con- ditions presented by these erect trees, no remains of any animals of higher rank than the Microsawria and Labyrinthodontia have been found deserves notice here. It seems to indicate that no small animals of higher grade inhabited the forests of Nova Scotia at the period in question; but this would not exclude the possibility of Dy 2 256 Mr. T. Gray. Electric Conductivity of Glass. [Jan. 12, the existence of higher animals of a larger size than the hollow trees were capable of receiving. Nor does it exclude the possibility of higher animals having lived contemporaneously in upland situations remote from the low flats to which our knowledge of the coal forma- tion is for the most part confined. It is to be observed also that as some of the reptilian animals are represented only by singie speci- mens, there may have been still rarer forms, which may be disclosed should other productive trees be exposed by the gradual wasting of the cliff and reef.” I]. “On the Variation of the Electric Conductivity of Glass with Temperature, Density, and Chemical Composition.” By Tuomas Gray, B.Sc. F.R.S.E. Communicated by Pro- fessor Sir WiLLIAM THOMSON, F.R.S. Received December 28, 1881. (Abstract. ) In this paper the results of the continuation of a series of experi- ments, some preliminary results of which were published in the “Phil, Mag.” for October, 1880, are given. The experiments were performed in the Physical Laboratory of the Imperial College of Engineering, Tokio, Japan. In the preliminary experiments it was found that the condietaee of glass increased with the temperature, following a similar law to that found to hold for other highly insulating substances. It was also found that the effect of successive heatings and coolings was to diminish the conductivity. Further experiments on this subject show that although the diminution of conductivity here referred to some- times occurs, it does not always occur, and does not seem to do so when the glass is newly manufactured. Reference is made to pre- liminary experiments on the effect of time on the electric conductivity of glass, the results of which indicate an increase in conductivity with time. The subject of the main part of the paper is an account of experi- ments on the relation between the electric conductivity of glass and its density and chemical composition. A large number of specimens of lime glass were examined, but, as was to be expected in this case, no marked connexion between electrical quality and density could be observed. It was found, however, on analysing a few specimens, that the composition of those which had a high conductivity differed con- siderably from that required to form an exact chemical compound, while those which had a low conductivity had a composition agreeing more or less closely with that required for a trisilicate of potash and lime, or a mixture of potash, lime, and soda-lime trisilicates. 1882.] Mr. H. Sutton. New Electrical Storage Battery. 257 A few specimens of lead or flint glass were examined in the same way, and in this case a very marked connexion between electric con- ductivity and density was observed. This result was, however, no doubt due to the fact that the density of this kind of glass gives an indication of its chemical composition. In all the specimens examined it was found that the higher the density the lower the conductivity. The highest density reached, however, was that in the case of a Thomson’s electrometer jar, which had a density of 3:172. On examining these specimens for chemical composition it was found that the electrometer jar contained almost exactly the proper amount of lead and potash to form a trisilicate of potash and lead. It appears likely, therefore, that the electric conductivity of glass is lowest when it is an exact chemical compound. It will be interesting to learn from future ex- periments if still more dense glass has a higher conductivity, and if the conductivity passes a minimum at the point where the pure silicate is reached. The author has to express his great obligation to his colleague, Dr. Edward Diver, in whose laboratory and under whose superin- tendence the chemical analyses of the specimens of glass were made. Ill. “On a New Electrical Storage Battery. (Supplementary Note.)” By HENRY SuTTON. Communicated by THE PRESIDENT. Received January 3, 1882. The new cell consists of a flat copper case, of the same shape as a Grove’s cell; it has a lid of paraffined wood, from which hangs a plate of lead amalgamated with mercury, the lower part of the lead plate being held in a groove in a slip of paraffined wood resting on the bottom of the copper case: through the hd a hole is bored for the introduction of the solution, which consists of a solution of cupric sulphate, to which is added one-twelfth of hydric sulphate; the pre- sence of this free sulphuric acid improves the cell at once. The following sectional sketch shows the arrangement :— 258 Mr. W. H. L. Russell on [Jan. 19, AB. The outer flat copper case. C. Plate of amalgamated lead held in grooves in the cap D and the slip E. F shows the hole in the cap through which the solution is intro- duced, and by the introduction of a glass tube through this hole the state of the charge is seen by observing the colour; the interior surface of the case forms the negative, and the amalgamated lead the positive electrode. January 19, 1882. THE PRESIDENT in the Chair. The Presents received were laid on the table and thanks ordered for them. The following Papers were read :— I. “On certain Definite Integrals.” No: 10, By Weesrieeie RUSSELL, F'.R.S. Received December 31, 1881. Let ay + aye + an? + age? + ayet=a+ B(mt ve + px”) + (w+ ve + pu?)?. Then we find the condition 8a, 4,2 + a3? —4a,a,0,=0, together with the equations— YP? = A) 2a,y= pds, By + 2Qypuv=a,, when there are three equations connecting the five quantities B, y, », Vv, p- Under these conditions we shall have— utvatpaa dz. 6% * Be+y2? a . | daetot tt a,02+a,0° + a,n* =| b =. 290), fb+Vvb-+ pb V Ap (z—p) +r? ( ) In the same way, if Ay + e+ Agu? + age? + ayez*+ azv + agv® =a+B(mt vet px?) +y(ut va + px")? + o(m + vat px?)?, we have similarly— utvatpa? dg , e%tBety2?+825 a Adeho TATU t? 40,02 +A .0* TA,05 Fae > — pee eee b be +b + Pb? V dp (2 —p)+v? (221). There will be six equations connecting the quantities a), ao, As, M4, 1882. ] certain Definite Integrals. 259 Ax, Ae, With B, y, 6, #, v, ep; Li bave not observed that these equations lead to an equation of condition between a), a, .. . * This transformation will apply equally well to all integrals of the form— fdab(ay)t+aye+ aon? +age>+a,*) . . . . (222), and f dad (d+ 2 + ag? + ag2° + aye*+a,0°+agu5) . . (223). If we consider the integrals {as sin (a+00+c6?+...00"%) . . . . (224), 0 and |‘ao Cosi(@ 1200 4-07). a 4 BO"). = «a eo). where « is not infinite, as it is in Fresnel’s integrals, we must proceed by expansion. Let 6=a+b0... ce”, u=sin 0, v=cos 0, du__ de di de saline) es eS ae d@ de do de fu _#0,,(d0),, #r__o,_ do, de de? doy de? doz = d@2 Proceeding in this manner, and remembering that when @=0, sin O=sin a, cos O=cos a, we are able to develope w and v with great facility, and so obtain the integrals. The following method may be very generally applhed. Let oO) = Ag+ a(S =) +4 (=) + where (a) is an arbitrary quantity. Then we shall have— |@@=|4* er v+a)%6(2) aie] {1 me ae +3(=") ge 3 {dot Ace “4 a,(2=4 aes (2 “2+a .} —a , B,(«—a\ , B,(e—a\? ) Sa Bo et | (ey + bs... 226), a“ ° aoa 2 \w+a = 3 \a+a Bi oa where By>=A,, Bj, =A,+2A,), B,=A,+2A,+3A, . The calculation of By, B,...is very easy. Form by addition the * Jan. 23. But Mr. Spottiswoode has discovered two conditions, which will, I hope, be inserted in the next paper on the subject. 260 Mr. W. H. L. Russell on [Jan. 19, series Ay, Ap +A,, A> +A,+A.+... Then by a second addition we have Ap, A, +2A,, A, +2A,+3A), or By, B,, Ba, ... Moreover, if the series Ap, A,, A,, &c., is convergent, the series B,. B,, B,, &e., is also convergent, because Bale Any + =F 2A, + SAn-} + 4 Ans +. iby on se DN n+ dA, 19, 4, BAG =e and if A,+, 1s in the limit less than A,, A, less than A;,,-.. Baty, must in the limit be less than Bz. Hence if the limits are greater than a, and the difference between either of them and a small when compared with (a), we shall have in many cases excellent convergence. This method of converging to the value of definite integrals is useful in dynamical problems. Another is as follows. Let d(x)=a+be+ca*+en+ ... ra"=22, tien ¢' las dz oo) +6) dz 6") +38" (@ 1. al ae ke. When z=0, x is one of the roots of a+be+cx?+ ...+7rx2*=0; calk it (2). Then a ie dz, dz? G'(a)’ Pe _¢ d4z_ —«12"(2) dz” dz (p'a)3 — 2g ” 4 Hence o— a SO A ae a (pa)? 2 3 " 5 edz EO ls oh jene pi Ae Sere (Gaye” 2. gv But fadz=ax2—f zdz. Hence fdaV a+ ba+ca?+en?+ ... tex be CED far} #28 \ 99,7 Fiat \“tagee (p'x)° O55 Gam Ca The limits are arbitrary; but the series evidently requires that ¢’(«) should be considerable. : 1 ; al Since Oe Name 0 vt) 1882.] certain Definite Integrals. 261 1 iL dl: i gitar Lea ee i, aoe n(n+1)’ 1 Le ® di 1—z2 2¢ —1 ea OE eek EI NI ; ik a ee n(n+1)(v+2) ORS [(deQ.—a)'ar= CEE CeOGEsS), &c. = &e., we have, if G(0) =A, +A,O+A@?+..., i A A es By t—2) dare ——9 z See ie, | (PS) a ee aCe GE IGEED) 2 Ce) This formula is most useful when n is very large, or when (n) is very small. Suppose n=100, then the tenth term is less than Ay 60,000,000,000,000’ and after this the terms continue to diminish, though not so rapidly. When is very small, we shall come to an integer (7) which does not differ sensibly from n+7, and therefore we are able to write the integral :— : A A 2k oA l—; oe ae, Op ea eee ka eee n(n+1) n(n+1)(n+2) Ue o@s Py ae whi n(n+1).. ome a i ae AG eS WA eee 1 2) gate a(n+1) nint+1)(mt2) n(iw+1)(m+2)(n4+3) Wy Aye (¢(0) — —A )—A,.-. —A,_}) . (229). n(n+1).. ee +7) In the same way we are able to find :— 1 [,@0—a)dee"Cog.0)? EPMA mney IVS ie te ol (3K) a" (log. «)?= ; since \; 093d) — =o) 1 also [xc lap Glenda (oyeeeae)) a) a ee (RSID) e 0 1 [deo —a, log. eR) ae Reine te annie (S22). 0 We must, however, observe that the functions involving log # are supposed convergent, whatever the value of log. #, when expanded. 262 Prof. J. Dewar. (Jan. 19) In a similar way we obtain [00 sin of (sin® 0) COS O12) | de eee eee) E 0 January 19, 1882.—From formula (226) it immediately follows that— |,220@)= 264 B Bat (oF a ee \ II. “Manometric Observations in the Electric Arc.” By Pro- fessor DEWAR, M.A., F.R.S. Received January 14, 1882. The experiments recorded in my former paper, entitled “ Studies on the Hlectric Arc,”* together with the numerous observations made conjointly with Professor Liveing on the spectrum of the arc dis- charge between carbon electrodes in different gases, led me to ascer- tain if the interior of the gaseous envelope of the ordinary arc showed any peculiarities of pressure. Pressure might be caused by the motion of the gas particles, the transit of material from pole to pole, electric action, or indirectly by chemical combinations taking place in the arc. As any effect due to the above causes must necessarily be very small, a delicate manometer capable of measur- ing easily the =3,th of a millimetre of water pressure had to be employed. The records of such an instrument in the present series of experiments, are complicated by the indirect action of the hot currents of air passing the poles, and the irregularities in the steadiness of the are which undoubtedly cause marked variations of pressure; yet by multiplying and varying the conditions of the experiments, it is possible to eliminate these secondary effects and secure reliable results. The general appearance of the apparatus used is shown in the diagram. A and B are two hollow carbons, similar to those I formerly employed in the separation of cyanogen from the are.f They must be free from all porosity before they can be used in the experiments to be detailed, and the drilled hole should not be less than 3 millims. in diameter. In order to fill up minute apertures in the carbons, and render them non-porous, they are placed in a porcelain tube and heated to a white heat in a current of coal-gas saturated with vapour of benzole. This treatment causes the deposition of a layer of dense metallic carbon over the surface of the tubes which renders them capable of with- standing a considerable interior pressure of air or other gas without exhibiting leakage. The hollow poles are connected by means of tubing * “ Proc, Roy. Soc.,’’ vol. 30, p. 85. + “ Proc. Roy. Soc.,” vol. 29, p. 188. (1882. Manometric Observations in the Electric Are. SD Qo 264 Prof. J. Dewar. [Jan. 19, with the two manometers. Two glass cylinders, ED and GF, 50 millims. in diameter, have each a uniform horizontal tube open at both ends, 2 millims. in diameter, marked GG’ and HH’, passine through the corks E and G, fitted in side apertures. When fiuid was added to a fixed level, these vessels constituted the manometers. The tubes leading from the hollow poles have been made of metal or thick india-rubber, and to prevent heating of the tubes and manometer by radiation from the arc, they have been carefully guarded by hollow tin screens (shown at C) through which a current of water flowed continuously. The lengths of tube between the manometers and poles have been varied, and in some cases the tube made into a spiral form has been immersed in water so as to guard against unequal heating. The little glass stoppers marked Dd and -Ff were convenient for the alteration of the zero point by the addition or withdrawal of fluid from the vessels ED and GF. In the experiments water, ether, and alcohol have been used in the manometers, but the largest number of the experiments have been made with ether. This fluid is most con- venient from its mobility, and the only precautions to be taken are to use plain cork stoppers instead of india-rubber, and to have a con- siderable length of tube between the manometers and the arc. In the diagram K is a millim. scale divided on glass, and H represents a levelling stand on which the apparatus is placed. By careful level- ling and the use of ether 1 millim. of motion of the fluid in the horizontal tube may be made to correspond to about the 250th of a millim. of water pressure. In the present investigation as the absolute value of the pressure is not so important as the general variation, | have not thought it advisable to give other than rela- tive records taken with the same instrument at different times; it is quite possible, however, to get absolute values of very small pres- sures by means of this instrument, and I have satisfied myself of its accuracy by measuring a series of pressures of soap bubbles of different sizes, which confirm the previous observations of Plateau that the internal pressure varies inversely as the diameter of ' the bubble. When the are passes between two pointed carbon poles it assumes two very different forms; in one case the envelope of the intensely- heated gaseous materials is well defined, almost spherical,in appear- ance, surrounding the whole of the end of the positive pole, but touching the negative only at a single point, without showing that close adhesion to the pole which is so characteristic of the layer of gas at the positive. At other times the arc is very unsteady, noisy with apparent blasts of green flame-looking ejections, which generally arise from the positive pole. These blasts are invariably associated with a great increase of intensity in the hydrocarbon and cyanogen 1882. | Manometric Observations in the Electric Are. 265 spectrum. While the arc is in this unstable condition manometric observations are impossible, as the small area of the carbon tube is rarely completely covered by the arc, so that the manometers often record neither positive nor negative pressures during the discharge. The effect of the hot poles on the registration of the manometers is to produce a small negative pressure when the arc has stopped, due to the passage of currents of hot air. Many experiments were made to ascertain if a local heating of the carbon tube caused any per- manent pressure. This was carefully tested by taking the are at right angles to a carbon tube placed in a block of magnesia so as to raise the middle of the tube to the highest possible temperature. Under these conditions the manometer connected with the hollow carbon remained perfectly steady, whether the tube was made the positive or negative pole of the battery. This experiment also showed that repulsion of the inclosed gas in the tubes through an electric charge, had no effect on the manometer. During the main- tenance of the steady arc, the manometer connected with the positive pole exhibits a fixed increase of pressure, corresponding to a motion of the fluid in the horizontal tube of the manometers employed, of from 50 to 150 millims., which is equivalent to from 1 to 2 millims. of vertical water pressure, in different experiments and under varied conditions. The manometer connected with the negative pole shows no increase of pressure, but rather on the average a diminution. When the are begins to emit a hissing sound, the pressure on the positive pole instantly diminishes, and when blasts are ejected from the positive in the direction of the negative, the negative manometer which had stood at zero before showed a marked increase of pressure. If a commutator is placed in the circuit, so as to quickly reverse the direction of the original current, the arc is not broken, but the manometers immediately record a reverse action. In order to equalise the temperature of the poles to some extent, the arc was taken in the middle of a block of magnesia, but the same results were observed ; the pressure is generally smaller in the hot crucible than it is in air. When the crucible gets highly heated and filled with metallic vapours, the arc will pass a distance of more than an inch, and in this con- dition the shorter the arc the greater the pressure. It was found advisable in these experiments to use a negative pole which had a sharp conical termination, otherwise the form of the arc in the block of magnesia was very irregular, owing to the high conductivity of the hot walls of the crucible. When the poles are brought into contact in the magnesia crucible, the pressure at the positive instantly falls. Whether air, carbonic oxide, or nitrogen filled the manometer and carbon tubes the results were invariably the same. The chief experi- ments have all been made with the Siemens machine, but a 70-cell Grove’s battery produced the same results. The use of the horizontal 266 Manometric Observations in the Electric Arc. [Jan. 19, are 1s a matter of convenience, as in this condition the manometers are least affected by air currents, but the same general action may be observed by the use of vertical poles. A thin carbon spatula placed in front of the end of the positive pole at once lowered the positive pres- sure of the manometer. This experiment does not prove much, as the carbon diaphragm causes a noisy and unsteady are until a minute hole is pierced by the current. It is probable that the diminution of pressure may be due to the instability of the arc. In the same way the action of the magnet on the arc causes an instant reduction of the positive pres- sure by withdrawing the arc from completely covering the end of the carbon tube, so that this action must be regarded as an indirect one. A small carbon tube connected with a manometer was inserted into the arc, passing between two solid carbons, so as to take a section at right angles to the passage of the current. In this condition the arc is apt to be irregular in shape, and to pass rather between three poles than two, but the average records point to an increase of pressure in this position also. When the negative carbon tube is about 1 millim. in diameter, and the point sharp and the tube short, so as to diminish any air friction, the negative pole manometer seems also to give a positive pressure. ‘The intermittent Siemens arc shows an increase of pressure at both poles. It appears from the above experiments that the interior of the gaseous envelope of the electric arc always shows a fixed permanent pressure, amounting to about a millimetre of water above that of the surrounding atmosphere. This looks as if the well-defined boundary of the heated gases acted as if it had a small surface tension. This pressure may be due to various causes: motion of the gas par- ticles under the conditions, transit of material from pole to pole, or a succession of disruptive discharges ; and a more elaborate investiga- tion will have to be made before the origin of the excess of pressure can be clearly defined. 1882. | On a Series of Salts, &c. 267 January 26, 1882. THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. The following Papers were read :— I. “On a Series of Salts of a Base contaiing Chromium and Wireas No. 1.” By We. J. Seu, M.A., F.LC., Demon= strator of Chemistry in the University of Cambridge. Com- municated by Professor G. D. Liveine, F.R.S. Received January 13, 1882. Various compounds of urea with metallic salts and oxides have been described by Werther and Liebig. Some of these are suggestive of an analogy between urea and ammonia, while others seem alto- gether anomalous. The following account of some chromium com- pounds of urea may help to throw some light on the nature of such compounds, for they appear to show that a very definite base is formed by a combination of urea with chromium. When powdered and carefully dried urea is moistened with chromyl dichloride, and the mixture vigorously shaken, the temperature rises considerably, and on treating the resulting mass with water, there remains undissolved, a green crystalline powder. The nature of the green salt thus obtained is at present under investigation. It is insoluble in alcohol, ether, and chloroform. It dissolves in hot water with decomposition, another salt separating out as the liquid cools in brilliant olive-green needles, which by a second crystallisation is obtained in a pure state. The examination of this body showed it to be the dichromate of a base containing the elements of urea and chromium, and to have the formula {(CON,H,);.Cr2} (Cr.0;)33H,0. The dichromate thus obtained is sparingly soluble in cold, more freely in hot water, and is decomposed by boiling the solution. Its aqueous solution gives green crystalline precipitates with platinic chloride and potassium ferrocyanide, but none with ammonia. The following results were obtained on analysis :— The numbers given refer to the dried salt, unless expressly stated to the contrary. [ Jan. 26, On a Series of Salts Mrs IW ade sell: 268 é- 66ET g9.§$ ee oe °° ee ee eo OO ee oe ee ee ee.g PS ee OEE 00- OOT G: SLVT TSG. PP. ZL Oa ee eo oe oo ee eo. eo eo Oley 8. FOL a0 Oe 219 oe ee ee 6Z- OL OFZ ee oe ee ve alv@) Tels 1G? | ho Oi || hee Oia) 2s ze as as ses ass €8- OF F- 209 ‘eo 22 EOrO) LI. G2 | OF-83 | °° 2 - = 1. & Oe ee een Ge) m faa) ie) ie) -€ | Go.6 | 68-8 G3. 8P SS aa 5 r9-6 | $8-6 | 76-6 | 20-OT | 91. OT 94-6 Wise oe ees eee) ‘dOVJUIIIIT 6L “Et ‘OL 6 ‘8 ‘L 9 1g i °S G “Ll “SISATVUW “ALOOUT, 1882. | of a Base containing Chromium and Urea. 269 1. 5531 grm. gave on combustion in oxygen ‘2061 CO, and 169 HO. 2. 32175 grm. gave on combustion in oxygen ‘11865 CO, and 1029 H,0. 3. 3262 erm. gave on combustion in oxygen ‘1189 COQ, and 1045 H,O. 4, -4147 orm. gave on combustion in oxygen ‘1499 CQO, and "1281 H,0. 95. 0541 grm. gave by Gottlieb’s process very nearly equal volumes of CO, and N, weighing :01919 and ‘01267 respectively. 6. °35065 grm. gave by Dumas’ process 62 cub. centims. nitrogen at 0° C. and 760 millims. 7. °324 orm. dissolved in water, excess of KI and HCl added, and the iodine titrated with thiosulphate, required 40 cub. centims., each cub. centim. thiosulphate=-00306 CrQOg. 8. ‘5253 grm. precipitated by mercurous nitrate gave °1628 grm. Cr,0s. 9. -9317 grm. precipitated by mercurous nitrate gave °2915 grm. Cr,03. 10. The filtrate from 5255 grm. after precipitation with mercurous nitrate gave, when evaporated and ignited, -1011 grm. Cr,Q,. 11. The mean of three concordant experiments gave on ignition 41-62 per cent. Cr,O,. Deducting from this the Cr existing as CrO., gives 10°56 per cent. Cr,O, or 7:24 per cent. Cr. 12. -4985 grm. crystallised salt (dried by pressure between bibulous paper) lost ‘0181 grm. H,O in vacuo over sulphuric acid, and no further loss at 105° C. The Chloroplatinate. When a hot solution of the dichromate is mixed with a‘solution of platinic chloride, and the mixture allowed to cool, the chloroplatinate erystallises out in long green silky needles. The compound is mode- rately soluble in hot, but very sparingly in cold water. The sparing solubility in cold water was made use of in preparing the bulk of this salt from washings and drainings from other compounds. After one or two crystallisations from hot water, the compound is obtained in a state of purity. The examination of the body led to the formula {(CON2H,);.Cr2} (PtCl,);2H0 being assigned to it. The following results were obtained on analysis :— The numbers given refer to the dried compound unless stated to the contrary. 1. -8698 grm. gave on combustion ‘2207 CO, and 2008 H,0. 2. 95362 grm. BS 5 2331 CO, and °22662 HO. VOL. XXXII. U 270 Mr. W. J. Sell. On a Series of Salts [ Jan. 26 3. 1383 grm. by Gottlieb’s process gave volumes of CO, and N (nearly equal) weighing ‘034986 grm. and ‘0224591 grm. respec- tively. 4, -09505 grm. by Gottlieb’s process gave volumes of CO, and N (nearly equal) weighing *0252056 and ‘0154869 respectively. 5. ‘2071 grm. fused with pure NaHO, acidified with HNO,, and titrated with AgNOs, using ferric sulphocyanate as indicator, required 17°85 AgNO; solution. 6. °3471 grm. burnt in a current of air, the chlorine caught by a column of pure lime and estimated gravimetrically, gave -428 orm. Ag(Cl. 7. 3208 germ. ignited, the mixture of platinum and chromic oxide dissolved, gave (09135 Pt determined as double salt with NH,Cl and ‘02364 germ. Cr,O, from filtrate by precipitation with ammonia. 8. 07973 grm. acidified with HCl, the Pt precipitated by H,S, and the Cr,O3 in filtrate after decomposition of body by boiling HNOs,, gave ‘0226 Pt and ‘C061 Cr,Os. 9, 1543 grm. acidified with HCl, and the Pt precipitated by H,S, gave after ignition in air ‘0446 platinum. 10. °8408 grm. crystallised salt (dried by pressure) lost at 100° C. -014 grm. H,0. The Chloride. This compound may be obtained from the original green body, or from the dichromate, by treatment with water and lead chloride. The lead chromate is filtered off, and from the filtrate the chloride is pre- cipitated in fine silky needles by passing in hydrochloric acid gas. The compound recrystallised from warm water is deposited in long bright green prismatic crystals, having the composition (CON,H,),.Cr.C1,6H,0. It is freely soluble in hot water, less readily in cold, the com- pound being decomposed by boiling its solution. Its aqueous solution is precipitated by potassium dichromate, the compound precipitated being similar in every respect to the dichromate just described. It also gives precipitates with platinic chloride and potassium ferro- cyanide, but none with ammonia, until the compound has been destroyed by boiling or otherwise. The compound is almost com- pletely precipitated from its aqueous solution by the addition of hydrochloric acid. The following results were obtained on analysis :— 1. :7943 grm. salt gave on combustion ‘4036; grm. CO, and 3369 grm. HO. 2. 48795 orm. titrated with Tr AgNO; required 28:16 cub. centims. 271 of a Base containing Chromium and Urea. 1882.) seen a ei cE OLR NC CE CC ey EE TE | be 99. T sg vs oe ve ws ea Sp.0€ | SO-TE ast 62- OT 06.82 | 98.82 | LP. 82 + i a PG | F0.9 " : oS 63: Z ‘OL 6 8 ‘LZ 9 G ‘'P % ZL T 00- OOT TP: 6 *e: Be me TT: Té €6. OT xe ns Té. OT 4 = ee €1- 82 ve es Sie OL. ¢ $9.¢ SP. 3 6&. 3 68-9 99.9 66:9 TO: 4 ‘odeqttA0.10 & 6 T ‘sts ATRUW 6» 6806 96 6. €f0Z 661 6€9 96 T- 06% 8- POT SP PPT ‘LOOT, oe ee OHS ES eR 4) PERE S) oe er oes LIN OE Oe SA) 37 OL 9 ery Soe eee eke ay Mr. W. J. Sell. 3. ‘1477 grm. (another sample precipitated by HCl) titrated with 272 On a Series of Salts [Jan. 26, AgNO, required 8:6 cub. centims. 4, -4274 orm. ignited left (062 grm. Cr,Os. 5. ‘0382 grm. crystallised salt dried by pressure lost at 104° C. "05025 grm. H,0. Theory. Analysis. | ile 2. 3. 4. 5. Percentage. Oso ae oe 144 13°87 13°85 EI Soins eee 48 4°62 4°70 Ne uipussen oe 336 O,, eeooe eevee 192 Cry : 104°8 10°09 0 56 9 94 Clipe ab aige66 213 20 °52 20°48 | 20°67 1037 °8 6H,O 108 9°42 9°33 1145 ‘8 The Sulphate. This compound is readily obtained from the preceding, by the action of silver sulphate. The silver chloride is filtered off, and the solution concentrated at a gentle heat or in vacuo. If the warm solution of the chloride be rubbed up in a mortar with the proper quantity of silver sulphate, a crop of crystals of this compound is deposited after filtration, on cooling, in short dark green prisms. The crystals have the composition (CON,H,),.Cr.(SO,),10H,0. The following results were obtained on analysis:— | , 1. :385 grm. salt, dried by pressure between bibulous paper, lost at 105° C. 0538 grm. water, and gave, when dissolved and the sulphuric precipitated by BaCl,, -208 grm. BaSQ,. Theory. Analysis. Percentage. Cee ne 144. He ee 48 Nowe 336 OPV aoe ee 240 Grae ep ib 1048 ODF e DAD ey eaB 356)... ek 18°54 LOE OR 180 NS O21) pica) eee 13°98 1292 °8 1882. | of a Base containing Chromium and Urea. 273 The Nitrate. This compound is readily obtained from the dichromate or chloride by nitrate of silver. If the solutions used are warm and fairly con- centrated, a good crop of crystals is deposited on cooling after filtra- tion. The salt separates from the warm saturated solution, or by spon- taneous evaporation in large, well-defined, dark green prisms, which are anhydrous, and may be represented by the formula (CON,H,),. Cr,(NO;),. The following determinations were made :— 1. -449 erm. crystallised salt lost no appreciable quantity of water at 104° C., and is therefore anhydrous. 2. 0908 grm. gave 25°67 cub. centims. nitrogen at 0° and 760 millims. 3. 378 grm. ignited left 0493 Cr,O.. 4. -22175 02895, Theory. Analysis. 2 3. 4. Percentage. Cie 144: fo. Ropede 48 IN phe eae 420 35 °09 35 °46 Os ASO CO eae 104 °8 8°75 ae 8 94: 8 ‘95 1196 °8 The Hydrowide. A mixture of the dichromate, cold water, and a slight excess of pure precipitated lead hydroxide, rubbed together in a mortar, the lead chromate removed by filtration and any excess of lead by a drop of the dichromate, yieids a bright green strongly alkaline solution. This solution appears to contain the hydroxide of the same base as the salts just described, for they are easily obtained from it by suitable reagents. A precisely similar solution may be obtained from the sulphate by means of barium hydroxide. The compound, however, is slowly decomposed in the cold, more rapidly on heating, the solution losing its alkalinity, chromic hydroxide separating out and urea remaining in solution. If the green aqueous solution be mixed with alcohol, most of the hydroxide is deposited as a light green precipitate, which may be collected, redissolved in water, and reprecipitated by alcohol unchanged. It is, however, difficult to prevent some decom- position occurring, especially in drying. On this account, I have not at present succeeded in isolating it in a sufficiently pure state for analysis. 274 Profs. Liveing and Dewar. [Jan. 26, Up to the present time, no compounds of chromium with ammonia have been described, which are analogous in composition to those forming the subject of this paper. The metal cobalt, however, forms. with ammonia the base of Frémy’s well-known series of luteocobaltie¢ salts, to which these compounds bear a marked resemblance. Com- paring the compounds at present analysed with the corresponding Inteocobaltic salts :— New Series. Luteocobaltic Salts. {(CON2H,))2Cr2§(Cr,07)33H,0 .... {(NH3)).Co,}(Cr,0;)35H,0 f (CON,H,),.Cro} (PtCl,),2H,O NG 4 (NH3),.Co,} (PtCl,),6H,0 {(CON,H,),,Cr.}C1,6H,0 eer CN). Co, Ole {(CON,Hy);oCre}(SO,)310H,0 .... {(NH3);.C0.}(SO,)35H,0 { (CON.H,) ;2Cr2} (NO3)¢ ++ {CNH3)1.Co2}(NO3)¢ Several other compounds are in course of preparation or analysis, and will form the subject of a further communication. I am greatly indebted to my friend and former pupil, Mr. C. T. Heycock, B.A., for much valuable aid in the analysis of these compli- cated compounds. I desire also to express my thanks to Professor Liveing for much valuable advice and assistance. If. “ On the Spectrum of Water. No. II.” By G. D. Liveina, M.A., F.R.S., Professor of Chemistry, and J. DEWAR, M.A., F.R.S., Jacksonian Professor, University of Cambridge. Received January 14, 1882. In our former communication on the subject of the water spectrum (“ Proc. Roy. Soc.,” vol. 30, p. 580) we stated that the spectrum we then figured did not by any means exhaust the spectra of flames we had observed, but it was as much as we had at that time been able to trace to water as its cause. We had, in fact, noticed in the spectrum of coal-gas and hydrogen-flames a still more refrangible but less intense series of lines; and we have since observed that this second series is produced under the same. circumstances as the first, and we therefore ascribe it to the same cause, namely, the incandescent vapour of water. It is easily produced not only by the flames just mentioned, but by the arc of a De Meritens machine when a current of steam is. passed into it, and by the spark of an induction coil without jar in moist air or other moist gas. When a large coil and jar are used it almost or wholly disappears. The accompanying figure is drawn from a photograph of the spectrum of an oxyhydrogen flame; and the wave-lengths marked on 1882.] On the Spectrum of Water. 2 4) 276 Mr. H. Tomlinson. The Injluence of [Jan. 26, it were derived by interpolation from the wave-lengths of the magne- sium and iron lines. The are of a De Meritens machine taken in a crucible of magnesia gave us, when a current of steam was passed into the crucible, both the water spectrum and the metallic lines on the same plate. The solar lines are marked in the figure in positions held by the corresponding iron lines. These photographs were taken with prisms of Iceland spar. None of our photographs show any more refrangible rays produced by water within the limit of trans- parency of Iceland spar, 7.e., below a wave-length of about 2200. II. “An Attempt at a Complete Osteology of Hypsilophodon Fox, a British Wealden Dinosaur.” By J. W. HULKE, F.R.S. Received January 16, 1882. (Abstract.) — The author, after givinga list of papers on remains of this Dinosaur, by Professor Owen, Professor Huxley, and himself, and noticing the great want of a complete osteology which might serve as a type, describes in detail the skull, including the dentition, the vertebral column, shoulder-girdle, and hip-girdle with the limbs, and compares their structure with that of other fossil and extant Sauropsida. He maintains the generic distinctness of Hypsilophodon from Iquanodon as typified by I. Mantellt, considering that the very different structure of their hind feet is decisive of this. The paper embodies the results of dissections of parts of several skeletons, and it is illustrated by figures of all the bones described. IV. “The Influence of Stress and Strain on the Action of Phy- sical Forces.” By HERBERT TomLINsSon, B.A. Commu- nicated by Professor W. GRYLLS ADAMS, M.A., F.R.S. Received January 18, 1882. (Abstract. ) Part II.—Hlectrical Conductivity. The temporary alteration of electrical conductivity which can be produced by longitudinal traction was measured for all the metal wires used in Part I, both in the hard-drawn and annealed condition, and, in addition, for carhon and nickel, by the following method :— The wires were suspended in pairs of equal lengths in an air-chamber 4, feet in length and 4 inches inner diameter. This vessel, which consisted of two concentric cylinders containing a layer of water 1882.] Stress and Strain on the Action of Physical Forces. 277 1 inch thick between them, stood upright on a stout table. The ends of the wire to be tested, and of the other wire, which will be called the comparison-wire, were clamped into three brass blocks which rested upon a support of hard wood placed on the top of the chamber. One of the blocks was twice the length of each of the other two, and into this was clamped one end of each of the wires; the other ends were clamped into the other two blocks. The blocks were provided with terminal screws, and a ‘“ Wheatstone’s bridge” was formed, having four branches consisting of the wire under examination, the comparison-wire, and two sets of resistance-coils each of about 100 ohms, but capable of variation by such small amounts as ‘1 ohm at a time. These resistance-coils were connected by caoutchouc- covered copper wire, several feet in length but of small resistance, to two of the brass blocks, and were also united to each other by a platino-iridium wire baving a resistance of ‘1 ohm, which was stretched along a scale divided into millimetres, and was traversed by a sliding- piece, which, by means of a suitable spring and catch, could be readily clamped to any part of the wire. By means of the resistance-coils and the platino-iridium wire an alteration of less than one in a million could be measured. As the change of resistance was in general very small, it was necessary to take every precaution to avoid sudden changes of temperature. It was necessary also to keep the galvano- meter-circuit always closed in order to avoid errors which would otherwise have arisen from thermo-electric currents. A single Le- clanché cell was employed for the current-motor, and with this it was possible in a large majority of cases to measure with the aid of a delicate reflecting galvanometer an alteration of resistance not exceed- ing one ina million. The wire to be strained was provided with a moveable pulley 2 inches in diameter, to which was attached by means of a stout wire passing through a small aperture in the table a scale- pan, and both wires were, before suspension in the air-chamber, surrounded with caoutchouc tubing, silk, or other insulating material. The electrical resistances of all the substances which were examined, were, with the exception of nickel, increased by temporary longitudinal stress. With nickel, however, of which metal a wire nearly chemically pure was at length with difficulty procured,* the resistance was found to dimimish under longitudinal stress not carried beyond a certain point ; but after this point had been attained further stress began to increase the resistance. The effect on nickel appears still more remarkable when we reflect that the change of dimensions produced by the stress, namely, increase of length and diminution of section, would increase the resistance. The specific resistances of all the substances, except nickel and * Through the kindness of Messrs. Johnson, Matthey, and Co. 278 Mr. H. Tomlinson. The Influence of [Jan. 26, aluminium, were increased by temporary longitudinal stress. With aluminium and nickel the speciiic resistances were diminished by stress not carried beyond a certain limit. With nickel and carbon it was necessary to introduce slight modifications of the original method of determining the influence of stress on the resistance. With carbon, though the increase of resistance produced by a given amount of stress was greater than was the case with any of the other substances except tin and lead, this was not so with respect to the specific resistance. 7 In the next table will be found the mean results of the different experiments made with the various substances in the annealed con- dition. Increase of re- | Increase per unit Increase of re- | sistance per unit, of specific sistance per which would be | resistance which unit produced by | caused by stress | would be caused Name of sub- a stress of sufficing to by stress suf- stance. 1 grm. per square | double the length | ficimg to double centim. — sig- of the wire. the length ef the nifies decrease of | — signifies de- wire. — Sig- resistance. crease of nifies decrease of resistance. resistance. WOT sere cies or 2111 x 10-¥ 4-180 2-618 Platinum ...... 2285 3 404 2 °252 Zine 4406 3 °379 2-118 Abie aarsaicie all: i 10546 2 920 1-630 Lead .. 17310 2-885 1 ‘613 Silver... ss 4272 3 °851 1°531 Coppensecrriicr: 2310 2°713 1 005 Carbonte. ci 9248 2 °480 0-980 Platinum-silver . 2346 2 °4:64 0°624 German-silver .. 1523 2°018 0 226 Aluminium .... 1896 1-276 —0°262 Nickel 2a ee tae —6 994 — 8-860 The numbers given in the above table are calculated on the assump- tion that the alteration of resistance is proportional to the stress; this was found to be nearly, but not quite, the case. With most metals the resistance increases in a greater proportion than the stress; but with iron which has been very heavily loaded for some time, the ratio of the increase of resistance to the stress producing it after increasing to a maximum begins to diminish; and altogether, we may say, that the results here obtained completely confirm those already recorded in * The numbers given opposite this metal are calculated from the results obtained for stresses carried up to the above-mentioned limit, and as in the case of the other substances, represent the alterations which would ensue if the changes of resistance were proportional to the stress for any amount of the latter. 1882.| Stress and Strain on the Action of Physical Forces. 279 Part I, which concern the temporary alterations of length produced by longitudinal traction. One of the most remarkable features discernible in the table is the similarity of the order of the metals, as given in the last column, to that of the table of ‘rotational coefficients ” of metals recently given by Professor Hall ;* indeed, so striking is the relationship in the case of the metals iron, zinc, aluminium, and nickel, that there would appear to be no doubt that a series of experiments made with a view of determining the effects of mechanical stress and strain on the ‘‘ rotational coefficients ’”? would be of the greatest value. Another point to be noticed is, that the alteration of the specific resistances of the alloys brass, platinum-silver, and German-silver is much less than that of the several constituents of these alloys, and at first sight there would appear to be some relation between the altera- tion of resistance caused by change of temperature and that due to mechanical stress; but it has been proved by these and other experi- ments that the increase of resistance caused by rise of temperature is in some cases one hundred times that attending the same amount of expansion by mechanical stress; and, apart from the fact that with nickel and carbon the effects of change of temperature and of longi- tudinal stress are of an opposite nature, it is evident that the former are to be attributed to other causes than mere expansion. The influence of permanent extension on the temporary alteration of resistance caused by longitudinal stress was examined, and the results obtained verified the statement made in Part I that ‘the elasticity of a wire is diminished by permanent extension not exceeding a certain limit, but beyond this hmit it is increased.” The effect of permanent extension on the alteration of resistance which can tem- porarily be produced in nickel by traction is very remarkable. Compression was proved to produce on the electrical resistance of carbon a contrary effect to that caused by extension; this statement applies to the alteration of specific resistance as well as of the total resistance. Stress, applied in a direction transverse to that of the current, was also found to produce in several metals both temporary and permanent alterations of resistance of a nature opposite to those resulting from longitudinal traction. The time during which the stress was allowed to act exercised with strips of tin and zinc a large influence on the amount of the temporary alteration of resistance which was produced by the stress. In the case of the strips of tin and zine also, the alteration of resistance seemed to be very much greater than when longitudinal stress was applied to these same metals in the form of wires. * “ Nature,” November 10, 1881. Abstract of a note read by Professor E. H. Hall at the meeting of the British Association at York. 280 Mr. H. Tomlinson. The Influence of [ Jan. 26, Stress applied equally in all directions by means of an hydraulic press was proved to diminish the resistance of copper and iron; and the experiments showed that the lowering of the temperature of the freezing point of water can be accurately and readily measured by observations of the change of electrical resistance of a wire. These experiments also furnished still further proof that the change of resistance of a metal wire caused by rise of temperature is due almost entirely to other causes than mere expansion. Experiments on the permanent alterations of resistance which can be produced by stress, furnish valuable information respecting the ‘limit of elasticity ” of metals. There are two “critical points” in every metal at which sudden changes occur in the ratio of the permanent extension due to any load and the load itself. ‘The first of these points fixes the position of the true limit of elasticity, and the second that of the “ breaking-point.”’ With iron there are three, and, perhaps, more ‘“ critical points.” The total resistance of most metals is permanently increased by permanent longitudinal extension, but with nickel the total resistance is permanently decreased, provided the extension does not exceed a certain limit: beyond this limit further extension causes the resistance to increase. The rate at which a wire is ‘‘ running down” under the influence of a load can be very advantageously studied by observing the permanent increase of resistance produced by the load. If P be the “breaking- load” of a metal, and p be the load actually on the wire, the decrease per unit of the velocity of the increase of resistance is inversely pro- portional to P—p: so that the breaking-load of a wire can be calcu- lated from observations of the rate of increase of resistance when a loaded wire is ‘‘running down.” The above-mentioned proportion is — constant not only for one and the same metal, but for all metals. The small effects which can be produced by permanent extension, hammering, and torsion on specific electrical resistance were very fully investigated, and are shown in the paper by a series of curves. All the metals examined, except iron and nickel, have their specific resistances increased by strain caused by the above-mentioned pro- cesses, provided the strain does not exceed a certain limit, beyond this limit further strain decreases the specific resistance. In the case of iron and nickel, on the contrary, the specific resistance is at first decreased and afterwards increased. The effect on the resistance of annealed steel produced by heating and suddenly cooling was also studied, and it was proved that if the steel be heated to a temperature under “dull red,” sudden cooling decreases the resistance; whereas if the metal be heated up to or beyond “dull red,” sudden cooling increases the resistance: the strain, there- fore, caused by this process, and that resulting from purely mechanical 1882.] Stress and Strain on the Action of Physical Forces. 281 treatment, are similar as regards their influence on the electrical resistance. In order to make certain small corrections rendered necessary by the changes of density of the metals after they had been subjected to extension, hammering, or torsion, these changes were very carefully measured, and were found to be in every case small. The amount of recovery of electrical conductivity produced by time in wires, which are in a state of strain, is shown in the paper for several metals by a series of curves, and these exhibit most con- clusively the superiority of platinnm-silver over German-silver when an accurate copy of a standard resistance has to be kept for a long period of time; in fact, of all the metals tested, German-silver showed the most marked recovery of conductivity, and platinum-silver the least. The recovery of electrical conductivity is in all cases attended with recovery of longitudinal elasticity and of torsional rigidity. A full examination of the influence of permanent strain on the susceptibility to temporary change of resistance from change of tem- perature showed that metals may be divided into two classes. In the first of these classes, which includes iron, zinc, and platinum-silver, the strained wire is most increased in resistance by rise of temperature up to a certain limit of strain, whilst beyond this limit further strain diminishes the first effect. In the second class, which comprises copper, silver, platinum, and German-silver, the strained wire is least imereased in resistance by rise of temperature, but that, here again, after a certain point of strain has been reached, the first effect begins to be diminished. It will further be shown in Part IV, that there must be some close relationship between the thermo-electrical pro- perties of strained and unstrained metals and their susceptibility to change of resistance from change of temperature, and that strain of any kind, whether produced by purely mechanical means, such as traction, hammering, and torsion, or by the process of tempering, renders a piece of metal thermo-electrically positive or negative to a similar piece of metal unstrained, according as the strained piece is caused to be less or more increased in electrical resistance by rise of temperature. After some trouble, means were found of measuring with consider- able accuracy at 100° C. the alteration of electrical resistance due to temporary longitudinal traction, and the experiments led to the belief that the elasticity of iron and steel is not temporarily but permanently increased by raising the temperature to 100° C. Subsequently direct observations of the elasticity made in the manner described in Part i, but on shorter lengths of wire, placed in an air-chamber, the tempera- ture of which could be maintained constantly at 100° C., proved beyond a doubt that if M. Wertheim, to whom we owe so much of our 282 Mr. H. Tomlinson. The Lnfluence of [ Jan. 26, knowledge concerning elasticity, had examined the elasticity of iron and steel after these metals, tested at the higher temperature of 100° C., had again cooled down to the lower one, he would have found that what to him appeared, in the case of these metals* to be a tem- porary increase of elasticity was really a permanent one, and if the wires used had been tested several times, first at the higher and then at the lower temperature, he would have also found, provided sufficient rest after cooling had been allowed, that the elasticity of both iron and steel is temporarily diminished by raising the temperature to 100° C. Not only is a comparatively large and permanent change produced in the elasticity of iron by merely raising the temperature to 100° C., but in the case of well annealed iron wire there is sometimes an enor- mous change produced in the ductility (in one specimen the ductility was diminished 50 per cent.) by the same process; and since very appreciable effects have been proved to be brought about in the same manner in the magnetic inductive capacity, the specific resistance, and the thermo-electrical properties of iron and steel, 1t would appear that researches on these properties might lend valuable aid in investi- gations gn the hability of wrought-iron axles to fracture, which is produced by sudden changes of the temperature of the air. It was further noted that shortly after the iron or steel has been heated and then cooled, there is less elasticity than when a rest of some hours has been allowed, and in fact we have in the case exactly the same kind of restitution of elasticity as we have seen takes place after a wire has received mechanical extension. With nickel the increase of elasticity produced by rest after cooling is still more remarkable. The effects of very slight mechanical strain, and of the strain caused by raising annealed iron or steel to 100° C., and afterwards cool- ing, on the torsional rigidity of these metals were next examined, and it was shown that the torsional rigidity is affected in a precisely similar manner to the longitudinal elasticity, both by raising the temperature to 100° C., and then cooling, and by the strain resulting from slight mechanical traction. On the whole it was seen that as regards either purely mechanical strain, or that caused by tempering, there are for iron and steel three critical points: very slight strain increasing, moderate strain diminishing, and excessive strain again increasing both the torsional and longitudinal elasticity. The temporary alteration of susceptibility to change of resistance from change of stress, which is effected in the case of nickel by raising the temperature to 100° C., is as remarkable as the suscepti- bility itself, and the maximum diminution of resistance which could be produced by stress when the metal was at the temperature of the room was actually more than twice that at 100° C. * “« Ann. de Chimie et de Phys.,’”’ 3me serie, 1844, p. 431. 1882.] Stress and Strain on the Action of Physical Forces. 283 The alteration of electrical conductivity which can be produced by magnetisation was carefully studied, and a full account of the modes of experimenting, of the apparatus employed, and the precautions adopted will be found in the paper. The substances examined were iron, steel, nickel, cobalt, bismuth, copper, and zinc, and in all cases, except that of copper, it was proved that longitudinal magnetisation increases the electrical resistance, whether the substance is in an annealed or unnannealed condition. With copper wire no trace of change of resistance could be detected when the wire was under the influence of a powerful electro-magnetic solenoid. In the case of zinc, which was in the form of foil, no alteration of resistance was discern- ible until the action of the solenoid was supplemented by that of a stout iron core, which was placed inside the solenoid and round which the foil was wrapped. In the next table will be found the increase of resistance per unit produced in the different substances by an absolute electro-magnetic unit of magnetising force, when the mag- netisation is longitudinal. | Increase of re- : : sistance per unit Diameter in B Name of metal. Condition. an nat ae produced by unit magnetising force. ome... | Annealed 2... .. 0:94 2335 x 10-8 Steel..........| Annealed ...... 0-85 1500 Steel 7... ......./| Unannealed...... 2°33 bI37 Seema inc. 4. | Very hard... .: 2°33 70 Wrekeloissccs...)| Amnealed ......% E05 8070 Nickel ........| Unannealed .... 7-00 4343 (ya) 2 ha ee Unannealed .... E50 628 Bismuth ..:...|/ Unannealed ... 3°30 2h Of all the metals examined, annealed nickel was by far the most affected by a given amount of magnetising force. The increase of resistance produced by magnetisation can be very accurately represented by the formula y=a.a+b.f8; where y is the increase of resistance, « the magnetising force, 8 the induced magnetism, and a, b constants for the same substance when the same amount of current per unit of area flows through the substance. When different strengths of current are used in measuring the resistance of annealed iron, the alteration of resistance caused by a given magnetising force increases with the amount of current per unit of area which flows through the substance. The induction current produced by the magnetisation of the iron in a coil surrounding the latter is also greater when a current is flowing through the iron than when it is not. With annealed nickel, or with unannealed steel, 284 The Influence of Stress and Strain, &. [ Jan. 26, there is little or no perceptible difference in either the increase of resistance or the induction current due to magnetisation, whether a current is or is not at the time flowing through the metal. In the paper curves are shown exhibiting the connexions between imcrease of resistance, magnetisation, and induced magnetism. From these curves, aud from the fact of the above-mentioned formula holding good, it is assumed that the resistance will go on increasing with the magnetising force even when the latter is so great that further increase of force does not produce perceptible increase of magnetism. In some remarks made in the paper on the nature of the alteration of resistance which is produced by maegnetisation, it is stated, that ‘had the nature of the change of resistance been the same for longi- tudinal mechanical stress as for longitudinal magnetisation in the case of all metals, there is nothing in the actual amount of alteration that might not lead us to suppose that the change of resistance from the latter cause is due to mere rotation of the molecules considered simply as molecules without regard to the electric currents, which, according to Ampére’s hypothesis, are constantly circulating round these molecules. But when we find, that with nickel, longitudinal traction, which must also cause to a certain extent rotation of the molecules, but without magnetic polarity, actually produces decrease of resistance, we are probably right when we conjecture, that the change of resistance resulting from magnetisation is in a great measure due to the fact that the current used in the ‘bridge’ is encountered by a set of molecular currents circulating all more or less in the same direction, and in planes more or less at right angles to the direction of the ‘ bridge’-current, according as the magnetism induced is greater or less.” These molecular currents would cause the current passing through the substance to flow spirally, and the effect would be aided by the action of the magnetising force itself, which action would go on increasing with increase of force, even when no appreciable further increase of indnced magnetism took place. Since Professor Hall has proved that such action is possible, and that nickel, iron, and cobalt are very conspicuous in this respect, we have some support for this view. The “circular” magnetisation which any magnetic substance undergoes when a current is conducted through it, seems to. have very little or no appreciable effect on the electrical resistance of the sub- stance, so that, if we compare the resistances of iron and platinum, the ratio of the two will be independent of the electromotor employed in the ‘‘ bridge.” The effects of temporary stress on the alteration by magnetism of the resistance of an iron or nickel wire are of a somewhat similar nature to those caused by the stress on the magnetic inductive capacity of 1882.] Presents. 235 these metals, and the same may be said with regard to the effects of the permanent strains due to extension, torsion, &c. Longitudinal stress which may be made to diminish considerably the susceptibility to alteration of resistance from magnetisation, cannot even when carried to the extent of causing breakage, change the nature of the alteration. There is apparently a close relationship between the “ viscosity” of a metal and its specific electrical resistance, and it seems very pro- bable that a full investigation of the former of these two physical properties by the method of torsional vibrations would afford valuable information respecting the latter. Presents, January 12, 1882. Transactions. London :—Anthropological Institute. Journal. Vol. X. No. 4. Vol. XI. Nos. 1, 2. 8vo. London 1881. The Institute. Art Union. Report, 1881. 8vo. London 1881. The Union. British Pharmaceutical Conference. Year-book of Pharmacy, 1881. 8vo. London 1881. The Conference. Hast India Association. Journal. Vol. XIII. No. 3. 8vo. London 1881. The Association. Entomological Society. Transactions. 1881. Part 4. 8vo. London. The Society. Linnean Society. Journal. Zoology. Vol. XVI. No. 89. Botany. Vol. XTX. Nos. 115-116. 8vo. London 1881. The Society. Royal Astronomical Society. Monthly Notices. Vol. XLI. Nos. 8,9. Vol. XLII. No. 1. 8vo. London. The Society. Neweastle-upon-Tyne:—North of England Institute of Mining and Mechanical Engineers. An Account of the Strata of Northumberland and Durham. 8vo. Newcastle-upon-Tyne 1878. The Institute. Paris:—Ecole des Hautes Etudes. Bibliothéque. Sciences Philo- logiques et Historiques. Fasc. 45-49. 4to. and 8vo. Paris 1880— Ok. The School. Ecole Normale Saene. Annales. Tome X. Nos. 8-12 et Supplément. 4to. Paris 1881. The School. Institut de France. Académie des Sciences. Comptes Rendus. Tome XCII. Tables. Tome XCIII. 4to. Paris 1881. The Institute. Muséum d’Histoire Naturelle. Nouvelles Archives. Série 2. Tome IV. 4to. Paris 1881. Rapports Annuels. 1879-80. 8vo. Paris 1880-81. The Museum. Société d’Anthropologie. Mémoires. 2e Série. Tome II. Fasc. VOL. XXXIIi. * 3 286 Presents. [Jan. 12, Transactions (continued). 1, 2. 8vo.- Paris 1875. Bulletins. 3e Série. Tome IV. Fasc. 1, 2. 8vo. Paris 1881. The Society. Société d’Hncouragement pour l’Industrie Nationale. Bulletin. 2e Série. Tome XVIII. No. 238. 4to. Paris 1872. 38e Série. Tome VIII. Nos. 89-94. 4to. Paris 1881. Compte Rendu. 1881. Nos. 11-18. 8vo. The Society. Société de Géographie. Bulletin. Mars—Mai, 1881. 8vo. Paris. The Society. Société Entomologique. Annales. 5e Série. Tome X. 8vo. Paris 1880. The Society. Societé Francaise de Physique. Séances. Jan.—Juillet, 1881. Svo. Paris 1881. Résumés. Juin—Décembre, 1881. 8vo. Paris. The Society. Société Géologique. Mémoires. 2e Série. Tome [X. Title-page. 3e Série. Tome 1. Nos. 4, 5. 4to. Paris 1879-80. Bulletin. 2e Série. Tome XVI. ff. 1025-1157. Tome XVII. ff. 45-52. Svo. Paris 1859-60. 3e Série. Tome III. No. 8. Tome IY. No. 5. Tome V. No. 8. Tome VI. Tables. Tome VII. Nos. 9,10. Tome VIII. Nos..2-6. "Tome 1X. Nos? 1=55icua Paris 1874-81. The Society. Société Philomathique. 7e Série. Tome V. Nos. 2-4. 8vo. Paris 138 The Society. Rome :—Accademia Pontificia de’ Nuovi Lincei. Atti, Anno XXXIII. Sessione 7. Anno XXXIV. Sessione 1-3. Ato. Roma 1880-81. The Academy. R. Accademia dei Lincei. Series 2*. Vols. V, VI, VII. Series 3?. Sci. Moral. Vol. VI. 4to. Roma. Transunti. Serie 3%. Vol. V. Fasc. 13, 14. Vol. VI. Fasc. 1, 2. 4to. Roma 1881. The Academy. R. Comitato Geologico. Bollettino. Vol. XII. Nos. 5-10. 8vo. Roma 1881. The Society. St. Petersburg:—Académie Impériale des Sciences. Mémoires. Tome XXVIII. Nos. 3-9. Tome XXIX. No. 1. 4to. Sz. Pétersbourg 1880-81. Bulletin. Tome XXVII. No. 3. 4to. Repertorium fiir Meteorologie. Tome VII. No. 2. 4to. Sz. Petersburg 1881. The Academy. Stockholm :—K. Svenska Vetenskaps-Akademie. Handlingar. Ny Foljd. Bandet XIV, Hatet 2; XV och Atlas; XVI; XVII. Ato. Stockholm 1877-81. Ofversigt. Arg. XXXVIII. Nos. 1-5. 8vo. Stockholm 1881. Bihang. Bandet 4. Hafte 1, 2. Bandet 5. Hafte 1-2. 8vo. Stockholm 1877-78. Minnesteck- ningar och Lefnadsteckningar. 1877-80. 8vo. Meteorologiska Takttagelser 1 Sverige. 1875-77. Ato. Stockholm 1878-81. The Academy. 1882. | Presents. 287 Transactions (continued). Turin :—Reale Accademia delle Scienze. Memorie. Serie 22. Tomo XXXII, XXXIII. 4to. Torino 1880-81. Atti. Vol. XVI. Disp. 5-7. 8vo. Torino 1881. The Academy. Utrecht :—Nederlandsch Gasthuis voor Ooglijders. Jaarlijksch Verslag. Nos, 6, 8, 9, 12, 16, 20, 22. 8vo. Utrecht 1866-79. Professor Donders. Physiologisch Laboratorium der Utrechtsche Hoogeschool. Onderzoekingen. 3° Reeks. VI. Afl. 2. 8vo. Utrecht 1881. Professor Donders. Observations and Reports. Berlin :—K. P. Akademie der Wissenschaften. Circular zum Ber- liner Astronomischen Jahrbuch. Nos. 161-173. 8°. The Academy. Brisbane :—Registrar-General’s Office. Statistics of the Colony of Queensland. 1880. 4to. Brisbane 1881. The Registrar-General of Queensland. Brussels :—Observatoire Royal. Annuaire, 1882. 12mo. Bruzelles 1881. The Observatory. Dublin :—General Register Office. Weekly Return of Births and Deaths. June to Dec., 1881. 8vo. Dublin. Quarterly Returns. Nos. 70, 71. 8vo. Dublin 1881. The Registrar-General for Ireland. London :—Admiralty. Statistical Report of the Health of the Navy, 1880. 8vo. London 1881. The Admiralty. India Office. Tide-Tables for the Indian Ports, 18382. 12mo. London. The India Office. Potsdam :—Astrophysikalisches Observatorium. Publicationen. Band II. 4to. Potsdam 1881. The Observatory. Abel (Niels Henrik) Cuvres Complétes. Nouvelle Edition. Tome I. Ato. Christiania 1881. The Norwegian Government. Chambers (F.) Brief Sketch of the Meteorology of the Bombay Presidency in 1880. 8vo. The Author. Geddes (Patrick) The Classification of Statistics and its Results. 8vo. Hdinburgh 1881. The Author. Goebel (Ferdinand H.) Die Wunder des Planetensystems, &c. 8vo. Wiesbaden 1880. The Author. 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Hermannstadt 1881. 3 The Union. 292 Presents. [Jan. 26,. Transactions (continued). Innsbruck :—Ferdinandeum fir Tirol und Vorarlberg. Zeitschrift. Folge 3. Heft XXV. 8vo. Innsbruck 1881. The Ferdinandeum. Naturwissenschaftlich-medizinischer Verein. Berichte. Jahrg. XI. 8vo. Innsbruck 1881. The Union. Jena :—Medicinisch-Naturwissenschaftliche Gesellschaft. Jenaische — Zeitschrift. Band XV. Hefte 2,3. 8vo. Jena 1881. The Society. Kazan:—Imperial University. Izvyestiya 1 Uchenuiya Zapiski. 1880. Nos. 1-6. 8vo. Kazan 1879-80). The University. Lausanne :— Société Vaudoise des Sciences Naturelles. Bulletin. 2e Série. Vol. XVII. Nos. 85, 86. 8vo. Lausanne 1881. The Society. Leipzig :—Astronomische Gesellschaft. Vierteljahrsschrift. Jahre. XV. Heft 4. Jahrg. XVI. Hefte 1-3. 8vo. Leipzig 1880-81. ° . The Society. Firstlich Jablonowski’sche Gesellschaft. Jahresbericht. 1880, 188]. 8vo. Leipzig. The Society. K. Sachsische Gesellschaft der Wissenschaften. Math.-Phys. Ciasse. Abhandlungen. Band XII. Nos. Ha, V, VI. 8vo.. Leipzig 1880. Berichte. 1880. Nos. 1, 2. 8vo. Leipzig 1880-81. Phil.-Hist. Classe. Abhandlungen. Band VIII. Nos. 2, 3. 8vo. Leipzig 1880-81. Berichte, 1880. Nos. l, 2. Svo. Leipzig 1881. The Society. Liége :—Société Géologique. Annales. Tome VII. 8vo. Liége | 1879. The Society. Lisbon :—Academia Real das Sciencias de Lisboa. Classe de Sci. Mat., Phys., et Nat. Memorias. Nova Serie. Tomo VI. Parte I. 4to. Lisboa 1381. The Academy. London :— Meteorological Society. The Meteorological Record, No. 3.. 8vo. Index to the Publications of the Hnglish Meteorological Societies 1839 to 1881. 8vo. London 1881. ‘The Society. Mineralogical Society. The Mineralogical Magazine and Journal. Vol. IV. No. 20. 8vo. London 1881. The Society. Society of Arts. . Journal. June to December, 1881. 8vo.. London 1881. ) The Society. Montpellier :—Académie des Sciences et Lettres. Section des Sciences. Mémoires. Tome X. Fasc. 1. 4to. Montpellier 1881. | The Academy. Stockholm :—Académie Royale des Sciences. Geologisk Ofversigts- Karta 6fver Skane. AfN.P.Angelin. 8vo. Lund 1877. The Academy.. 1882. ] Presents. 293, Observations and Reports. Calcutta :—Geological Survey of India. Palzontologia Indica. Ser. XIV. Vol. 1. 3. Fasc. 1. 4to. Calcutta 1882. Records. Vol. XIV. Part 4. 8vo. The Survey. Meteorological Department. Observations at Six Stations. April to July, 1880. 4to. Indian Meteorological Memoirs. Vol. I. Part 5. 4to. Calcutta 1881. The Meteorogical Reporter. Survey of India. General Report on the Operations. 1879-80. folio. Calcutta 1881. The Surveyor-General of India. Dehra Din :—Great Trigonometrical Survey of India. Synoptical Volumes X-XIII. 4to. Dehra Din 1880. The Survey. Geneva:—Observatoire. Résumé Météorologique de PAnnée 1880 pour Genéve et le Grand Saint-Bernard. Par H. Plantamour. Svo. Genéve 1881. Professor Plantamour. Greenwich :—Royal Observatory. Spectroscopic and Photographic Results. 1880. 4to. Account of Observations of the Transit of Venus, 1874, Edited by Sir G. B. Airy. 4to. London 1881. The Observatory. Haye (la) :—Commission Beolomene Néerlandaise. Publications. No.1. 4to. La Haye 1881. The Commission. London :—Local Government Board. Epo of the Medical Officer for 1880. Svo. London 1881. The Board. Meteorological Office. Daily Weather Reports. January to June, 1881. folio. Hourly Readings. pojgeue ee and October, 1880. folio. The Office. St. Bartholomew’s Hospital. Statistical Tables. 1880. 8vo. London 1881. ‘The Hospital. Pulkowa:—Observatory. lLibrorum in Bibliotheca Speculee Pulco- vensis contentorum Catalogus Systematicus. Pars II. 8vo. Petropolt 1880. The Observatory. San Hernando :— Instituto y Observatorio de Marina. Anales. Seccion 2a. Observaciones Meteoroldgicas. Afio 1880. Ato. San Fernando 1881. The Observatory. Stockholm :-~Bureau Géologique. Afhandlingar. Ser. C. No. 42. Ato. Stockholm 1880. The Commissioners. Toulouse :—Observatoire Astronomique. Annales. Tome I. 4to. Paris 1880. The Observatory. Washington :—Bureau of Navigation. Astronomical Papers pre- pared for the use of the American Hphemeris. Vol. I. Part 5. 4to. Washington 1881. The Bureau. Department of Agriculture. Monthly Reports. 1873, 1874, 1878, 1879. 8vo. Washington. The Department. Office of the Chief of Engineers, U.S. Army. U.S. Geological and Geographical Survey of the Territories. Bulletin. Vol. VI. No. 2. 8vo. Washington 1381. The Office. 294 Mr. J. B. Hannay. Observations, &c. (continued). Office of the Chief Signal Officer. Daily Bulletin of Weather Reports. June to August, 1877. 4to. Washington 1879-80. Annual Report of the Chief Signal Officer, 1879. 8vo. Wash- ington 1880. The Office. Office of the Surgeon-General U.S. Army. Index-Catalogue of the Library. Vol. II. 4to. Washington 1881. The Office. West Point :—U.S. Military Academy. U.S. Geographical Surveys west of the 100th Meridian. Vols. II-VI. 4to. Washington: 1875-80. The Academy. Adams (A. Leith), F.R.S., G. H. Kinahan, and R. J. Ussher. Explo- rations in the Bone Cave of Ballynamintra, near Cappagh, county Waterford. 4to. Dublin 1881. The Authors. Campin (Francis) The relative merits of Vacuum and Air Pressure Brakes. 8vo. Leeds 1881. The Author. Saint-Lager (Dr.) Nouvelles Remarques sur la Nomenclature Bo- tanique. 8vo. Paris 1881. The Author. Struve (Hermann) Fresnel’s Interferenzerscheinungen theoretisch und experimentell bearbeitet. 8vo. Dorpat 1881. The Author. Todd (D. P.) Report on the Total Solar Eclipse of 1878. Ato. Washington 1880. On the Use of the Hlectric Telegraph during Total Solar Hclipses. 8vo. Observations of the Transit of Mercury, 1878. May 5-6. 8vo. And three Reprints from the American Journal of Science. The Author. “On the Limit of the Liquid State.” By J. B. HANNaY, F.R.S.E., &. Communicated by Professor G. G. STOKES, LL.D., D.C.L., &., Sec. B.S. Received February 22, 1881. Read March 10, 1881. The uncertainty which characterises our knowledge of the true con- dition of a fluid immediately above and below the critical temperature, induced me to enter into a full examination of various fluids, with the object of gaining accurate definitions of the liquid and gaseous states, as well as to arrive at a true conception of the state of matter to which the term vapour can be applied. In a former paper, which the Royal Society has honoured me by publishing,* experiments were detailed which seemed to show that the liquid state terminated at the critical temperature, and that no amount of pressure would suffice at any higher temperature to render the fluid capable of exhibiting * “On the State of Fluids at their Critical Temperatures.’’ ‘ Proc. Roy. Soc.,” vol. 30, p. 484. On the Limit of the Liquid State. 295 surface tension or capillarity ; in fact, that the state of a fluid above that temperature coincided with the properties we call gaseous. The paper concluded, ‘‘ The difference between the liquid and the gaseous states is not then entirely dependent upon the length of the mean free path ; but also upon the mean velocity of the molecule.” That is to say, we may compress a gas (when a few degrees above the critical tempe- rature) to a less volume than it might occupy as a liquid, and it will still remain gaseous. In the following paper, therefore, the term liquid will be applied only to such bodies as exhibit surface tension. either as capillarity or by forming a permanent limiting surface when in contact with a vapour or gas. The term gas will be applied to that state of a fluid which precludes its being reduced to a liquid by pressure alone, in other words, to any fluid above its critical tempera- ture. The term vapour will be applied, as has already been done by Andrews, to fluids which can be reduced to liquid by pressure alone, that is, to any aériform fluid at a temperature lower than the critical. Thus carbon dioxide is a vapour at ordinary temperature, but is a gas at temperatures over 31°. A further distinction of gas and vapour lies in the fact that, on increasing the pressure, the volume of a gas goes on diminishing in a regular way, whereas there is a part of the curve representing pressure and volume of vapour where the curve 1s asymptotic, that is, where the vapour is in contact with its liquid. In the following paper reasons will be shown for believing that the gaseous state depends entirely upon the mean velocity and not upon the mean free path of the molecule at all. The difference between vapour and liquid, on the other hand, is entirely one of the length of the mean free path. The methods of experiments used were similar to those detailed in the paper above referred to, but a larger appa- ratus was employed, so that the results might be more distinctly visible. It was soon noticed that the readings of pressures of mano- meters varied a little with the diameter of the tube employed, the smallest bore giving the highest reading, and this was the case to such an extent as to cause an error of two atmospheres in 70, and about five in 100; the higher the pressure the greater the difference. The wide tube was about 0°8 millim. in diameter, the smaller 0°1 millim. Now, whether this error was caused by the hydrogen condensing against the glass, and being thus lost as a manometric substance, or whether it was caused by the hydrogen being dissolved in the film of moisture which may be supposed to adhere to the interior of the tube, has not yet been determined. It has been shown by Professors Liveing and Dewar that the moisture adhering to glass is not driven off till nearly a red heat is reached, and we may be sure that the -eapillarity of the smaller tube would cause it to retain moisture more eagerly than the larger one. Whatever was the cause, it was almost invariably found that manometers with small bores gave higher read- a ae - iS S = 3S an jaa) ar = BO Seo ee obormoe soc SSeS sosogsk) — Tea errr re jsonerereiren am i [Cl = [=1=1 EE : ee eet Se Se Ge Geo cee =I= On the Limit of the Liquid State. 297 ings than those with wide bores. They were dried by passing dried hydrogen through them for over two hours and keeping them warm all the time. In order to obtain readings which would always be near the truth, and be more independent of accidental errors, an apparatus was con- structed. with two manometer tubes, and the manometers were made of tubes as wide as was consistent with the strain they were destined to bear. The apparatus as used is shown in fig. 1, where the two manometers are shown fixed in the two upright branches, while the pressure screw is at the right hand, and the working tube at the left. The air-bath has been drawn as though it were transparent, to show the internal arrangement. The working tube is recurved, so that the liquid to be experimented upon is contained between the mercury and the sealed top of the tube. The air-bath consists of two cylindrical baths with holes in the lids for passing the working tube through, and an outside cover which keeps the heat from the lamp from bein too quickly radiated. The internal baths are supported by one of Fletcher’s solid flame burners, and the bottoms are covered by a layer of non-conducting cement. The outside cover has openings at the top for the escape of the burnt gases, and its top is covered with a thick layer of asbestos wool, to prevent cooling. The whole of the baths and cover were made of iron, as the high temperature used caused copper to scale heavily. Two thermometers were used in the bath, one on each side of the working tube; and at first each thermometer had a little one fixed to it for temperature corrections, but it was subsequently found that one hung between the two gave quite as much accuracy. The two thermometers used were of soda-glass with cylindrical bore, and registered the same temperatures to within 0°°5, being - chosen from a number. They were heated and cooled from 270° to 0° over seventy times, and one sent to Kew, where it was compared with the standard up to 100, and the stem calibrated and the corrections up to 350 calculated. The zero points of both thermometers rose from 0°-2 to 2°-2 during the preliminary heating and cooling. The changes were determined daily. The temperatures given in this paper may, therefore, be considered practically correct. . Two small thermometers were fixed to the manometers for tempera- ture corrections. After trying several stands I found that shown in fig. 1 to be the most convenient and steady; it is simply a large block of wood with a groove cut in it, in which the tube lies, the two upright arms preventing any movement of the apparatus. The packing of the joints has been described before, and I would only add that I find it better to face the India-rubber packing with leather by fixing a piece oi fine soft leather to the face of the plug with india-rubber solution. 298 Mr. J. B. Hannay. This leather face is then oiled, and can be screwed up with much less damage to the india-rubber plug. The larger the screw the more easily is it kept tight. The first screw I used was 58; of an inch, and it soon cut the leather facings; the second was -5,, and it was found to last much longer; and now working with a half-inch screw it has not required repacking for three months, although in constant use. The dimensions of the apparatus as used are as follows :—Length of hori- zontal tube, 24 inches; height of vertical branches, & inches; caps, 2 inches long by 12 inches diameter; screw, 4 inch; external diameter of tube, 14 inches ; internal diameter, 2 inch; length of manometers, 22 inches to 26 inches; external diameter, + inch to 2 inch; internal diameter, from 334, inch up to 4, inch. Small bath, 5 inches high by 4inches diameter; larger bath, 7 inches by 6 inches; externai cover, 13 inches high by 9 inches diameter. In each of the baths and in the cover two vertical slits were cut and fitted with mica windows, and a light placed behind allowed an observer to see clearly what occurred. The measurements are given in Hnglish standards, as engineers who construct such apparatus always use that method of measurement. As Amagat has shown that hydrogen is the only gas which follows Boyle’s law at high pressure, that gas was always used as the mano- metric substance, and was carefully purified and dried before use. The drying was done by passing it through five J-tubes with pumice- stone and strong sulphuric acid, and then through two (J-tubes with phosphoric anhydride. The manometers used were always 0°4 millim. in internal diameter, as narrower manometers always gave higher readings. In determining the pressure of alcohol at its critical tem- perature, the difference of pressure indicated by different manometers puzzled me at first, especially as there was no difference in temperature, but upon determining the diameters of the manometer tubes it was found that the highest pressures were registered by the smallest bores. The pressure of alcohol at its critical point as registered by the different manometers was as follows :— Temperature (theory). Diameter in Pressure in 3 millims. atmospheres. Ao ya EA me Ree OAD» a ere ORE Zoo Od, eo eee O-272- 2) 29sec O9gl DOO SVD” iy Dee eS iedeoete ASO AS) 2 ) feat 63 ‘1 Po OOM) Sit ieraete 05028 +o Vee 67 °9 These numbers are the means of thirty measurements in each case. The manometers A and B were used in most of the first portion of the work, but as they both broke subsequently, they were replaced by two — others, A’ and B’,and these again by A” and B”’. When a pressure of On the Limit of the Liquid State. 299 over 300 atmospheres is required, these wide manometers are very apt to burst, so that for high pressures a narrower tube must be used. The first work undertaken was to ascertain without doubt the eritical point of pure anhydrous ethyl alcohol, and this was done as follows :—The alcohol sold as absolute by the makers was fractionated, and the middle third taken. This was placed in a retort with freshly burnt lime, and an inverted condenser adapted to it. After it had been boiling for some time, the end of the condenser was fitted with a drying tube of calcium chloride, to prevent moisture from entering. The cohobation was continued for a week, and the alcohol then dis- tilled off. The first fifth was rejected, as was also the last. The receiver was a small flat-bottomed flask, which is shown fitted up for use (after it was filled with alcohol) in the front of the drawing. It was arranged as a wash-bottle, having the tube for the entrance of air connected with a small vitriol tower, and an india-rubber ball, fitted with valves, to apply pressure. The exit tube was adapted to the experimental tube by a piece of india-rubber tubing, through which was forced a piece of capillary tubing. When the apparatus was to be used in experiment the arrangements were made as follows :— The cap with the pressure-screw was first fitted on next the experi- mental tube, with its point sealed up, and the whole filled up to the top of the manometer branches with mercury. The manometers were now placed in position and screwed tight. The apparatus was then tilted so as to raise the point of the experimental tube, keeping it, however, above the level of the lower ends of the manometers, and the point then broken off. If the point were below the level of the manometers some gas might escape. ‘The wash-bottle arrangement is then fitted to the experimental tube and the ball compressed. Alcohol is driven over and escapes by the capillary tube, and this is continued till the inside of the tube has been well washed and all impurities removed. The capillary tube is then withdrawn, when the small puncture in the india-rubber at once closes itself. The screw of the pressure apparatus is then retreated, and when sufficient alcohol is made to enter the apparatus, the joint is undone and the whole wash- bottle arrangement placed under a bell-jar over oil of vitriol for use another time, the india-rubber tube being clipped. The screw is then farther retreated to leave a small air-space over the alcohol, which is then boiled and the point sealed, and the tube placed in the air- bath. A mercury regulator, such as I have described elsewhere, was sometimes used when the temperature was required to be constant for long. The following tables contain some of the series of observations on alcohol, and are given to show the numbers obtained when the work is done with every care. The alcohol used was different in each case, so that slight variations in the averages may be due to differences in the 300 Mr. J. B. Hannay. liquid used. The numbers for pressures are arbitrary scale readings, and are reduced to actual pressures at the end of the tables. Table No. I. Critical Temperatures and Pressures of Alcohol. T and I” are the two thermometers in the bath, one on each side of the experimental tube. ¢t and t’ two thermometers for correction of T and T’. P and P’ are the readings of the twe manometers A and B. t’ and t’’ two thermometers for correction of manometers. lig Lhe & De dug IPeaae Bh inte 253 254 LOO ESSA ie en 1802) 2247-5 = VG Reneeeay 232, 233 CS ISO RI enn 1878)". 22478 ang 16°8 232 254 Fuad 1S kaa reas Ak. 1859" 2235040 Ls 235 235 (SRE OO Mean eas 188-5 225 IM Ged 230 230 SPM Oa aes ars Gi 18559") (22 3eone ee 132 252) a0 1) OO FOO. Waar e - 1924) 225/57 eee 15 233 ZIbVO ROO Oye ie amenrene LIL" 6% 220% oes 15°5 232 PASI eae G15) op: KOC ou shat gs oncve. = P8620) 224 ores 15 232 230 SON NSO © ake ere 1876)" 224057 eG 16 232 230 OZ Som te teaceae 187°8 | (224:°8") Stoo lines 231 234 fo wah COC fe denar owls alegre 187 °8 = 22457), TO=2 SiGe 235 DSA ey) NOG) Mn Ocy ann nie 181 *5 22355" 7 comaleg 234 254 OEE 2ene tes ts hee 187 -2-)) 2245) Say ee ales Zoe Oy eon MOO Oat mee ween ets 188 °5” | 2248 Sas 236 237 SOM NS Oley ene catan. 188 224°°7 “16 Gee 233 232 BOF ne SAon TM ae a 186°9 224 Loch Moire 235 236 QR OOM cute c: 187°2 =224°5 14-5 15 231 252 BAS AO OM tere. ts 185:2 | 2240" “1b coals 230 231 BZ shy) SSAct ces, 193°6, 22559" iG e teas 230°5 232 Dar ES DBs tert 184 220 °S) VG E22 DBO 8 220) 7a0 WS) sO Uaniiee ar cy. 187 224°5 16 16 231°5 254 B82)" SO sete 186°1 © 2246 aes 15 235 0. oo On OOO) Ome Enete 185 4 2242 ee 16 °8 234 234 DOC Oe SO ieamanes. 196'°7 °°" 220 "5 7 7s are 233 230 SEY SO. eect 196 °3°-s ©2260" 4) LORS Gas 253 234: O22 erensten. 189°4 9225 20 ore 253 232 Oo.) (OOM AE arene TSS hore 225 LS" ais 232 231 BO. GSN ig ner ee 188°5. 224°8 " WOG2 ae 229 231 Ch Mites 3S Yan ehh ct ou hee 186°8 | 2244» Sioa 230 POL a6 G0 Col) a eeeente 186"6" 22445 aso aia 229 230 13 OS. OO mee tee 186 2240-2" AG 16 231 250 ODT OOM ie wena 187-2 - 224055) aren orale On the Limit of the Liquid State. 301 Pp. dhe t. t’. i Be. Gee tie 233 231 GI TAGE so 43 181°5 223°5 0 14°9 15°5 231 230 (POA ITT) a TSks4s 22536 LOs2 N72 230 EO ORM SANTO) acy 5 te 185°2 224°3 315 15°5 229 229 SPE SOM Ale: a8shs NSA 6 7 22402 2 16-2) S72 230 DOO BUM |) GOL ae oi thebe 187-8) 22408 18:5 16-7 231 231 GON! OZ 3. as: WS ey) Bal) 17-2 18°5 Peco colo Sp | 9008 2. 185°2 224°8 19 16 232 oO) TOOL: SOLOS.) er. 182°7 = 224°2 = =16 15 °9 Portion of thermometer scale exposed, 80° to 232°. pwnage Lae a Corrected average 235° ‘67. He T’ 232° -21 Height of mercury in manometer above tube P =0 ‘91 atmos. 99 9) 9? 99 P=] "14 99 age z ce {pressure in atmos. Corrected } 3 5 b67-56 atmos. Probable error of mean temperature 0°19. 9 by pressure 0-13. Table II. Critical Point of Alechol continued. Manometers A’ and B’. TY. a ie live 12 iP Ee Ee Pole eso 82" 78° Meu 148) (=O) Wes 285, 9 CR 0 aan a 987 140° 20), 19s OSE OBS ea: 2 9agn) ds. 19, = 0 125 DOSES a.) ely 988 144 20 20 eM 203 SO N85) ee. 9878 140.) 1m on ey SNe VON ee, 990 148 20 20 Deemte Jee 1 82) SI oe, 987 PAOi 4) QO ee 200). 79) RBA. 990 147° 19 “1835 e229) | B08 FO ies, 988) TAS Ge, ie pee 229 79 7B 987" 140. NG 685 22) IBC) Nese) Sia?) ea 987) . 140. 4 17-5 46 Poe SF. “OF 986 5 140 09 175 Mae, Peet he St! eek. 987. 140°5 16°5 16°5 25) he 988 TAA a Mb Pee 7. 84) SOM ee. 9870 tA Nee. 16 MOBS 75. BN oe 980) 448 SPR ges Bee 2 78) BI 290) AS) Dees. 118 ee? 6 79h 798 ea 990 149 - 18-5 18 VOL. XXXII. Y 302 Mr. J. B. Hannay. mT. is i: i PE. Pe: ue. 231°8 231°5 80 SON PO kiwis 288 147 18 231°8 232 82 (95 BE Soe 287 142 17 2al°5 232-2 8 BO" CR see 288 144. 16 232 °2 232°2 80 CO) Stew ce: 288°5 145 16°5 232 232 80 col! KAN ee anes ee 287 142 16°5 232°2 232°5 81 SON Eiices 287 140 17 232 232 85 Sits Be a 285 138 16°5 232 °2 232°2 76 SOMO hase. 287 14.2 15°5 232 232 07 (hotel penne ear 285 138 15 PAIL te) ABV AAA 75 EO Di Senta 288 145 14.°5 232 232 80 CD bn. 287 142 15°5 232 232 78 SO ie teers 287 143 15 Portion of thermometer exposed, 82° to 232°. Average of T 231°:87 | zs T’ 231°°85 J Height of mercury in manometer above experimental tube— Average P 287°66 66°90 y - 8° P’ 49-17 \ Corrected mean pressure : neck 66°88. Probable error of mean temperature 0°16. we zm: pressure 0:09. Table III. Critical Temperature and Pressure of Alcohol. Manometers A” and B”. Es 18 ly 16 16 17 AW; 18 16 15 14°5 15 15 Corrected mean temperature, 235°°43. qT. Ly t. Oe le Be bie ae 232 232°5 82 COMM iicr ties 212 122°38 16 18 230 232 75 ey" hid eee ee 212°5 12325 ae 17 232 2ao2 Le DOR tits 5s 213 125 1 18 232 °2 232°5 80 SU Mie tsa. @) 211 121 20 19 232 °2 232°5 32 CUS iecleie as 210°5 120 20°5 20°5 232 232°5 84 SON cere t 211 121 20 20 233 232 80 SOM patie ss 211°5 122 19 19 232 232 °2 80 CAS OE, See 212 123 18°5 18 231°5 2382°3 80 CASI Ted Meera eater 212°2 123°4 18°5 17 232 231°5 80 Silay pees. 212°1 123:2 18°6 19 232 °5 232 85 ro) eee eee 211°9 123 19 19 23l+5 231h:8 82 OB ach rah 212 121 18 17 232°5 231°5 89 oy Rote Wer Saget 212°3 1238°7 17°5 16 232 232 72 CORRE | Mae 211°6 121°8 16°5 16°5 231°5 2382°5 74 CORAM pc ees 212°2 122-7 14:2 14 On the Limit of the Liquid State. — 303 ls 1. t. ve Py Pe i. Lhe 234: 232 °5 70 GO GOUT Be. de 212°5 124 14°5 15 232. 9 232 78 BELO? BEY. 213 125 16 16°5 231 231 79 CIAL WOR LRO). 211 120°5 16 16 230 229 77 SOM Roe fee: 210°5 120 15°5 15°5 2al°s 230°5 7d SOF tia seca Bb 211°8 121 15°5 16 232°5 232 82 SES. Res Zales peli 15°5 16 233 231 83 SA, tab: 211-3 123 16 15 232 231°5 84 Sots! one PA E33 16 16 232 231°8 31 SOM ty) 1h aie 212°0 122°8 16 16 232°5 2382 85 Bor fae Qe sGe 212 °2 1238 15°5 16°5 233 232°5 80 SOP Sc) a 211°3 122 onto lotie 231 231°5 80 SUG .LGs8 15 2 22 17 17°5 231°5 231 79 TON AR OE. Ab2GOReLZS oy 819 18 229°5 230°5 75 SOP. walt. Baas. 212°2 1238 15°5 15 231°5 232 78 SOR Me | Aesee 211 121 15 15 232 231 75 PAS PY AES hte: 212°2 122°8 16 15 9325 232°5 78 Ate, PRL He Ze gon L239 18 17 Portion of thermometer exposed, 80° to 232°. Average T 231°:88 eet 2377 Height of mercury. in manometers over experimental tube— Average P 211:92 66°75 P’ 122-48 66°82 Probable error of mean temperature 0°10. # ri pressure 0:06. \ Corrected mean temperature 235°°39. } Corrected mean pressure ‘ \ 66°78 atmos. 9? We see from the foregoing tables that the mean of over a hundred experiments gives a critical point for alcohol of 235°°47 under a pressure of 67:07 atmospheres. The reason why so many experiments were done was because the first two or three series did not agree well, and it was only after some experience was gained at the work that good results were obtained. I have no doubt that by further refining of the methods better results would be obtained, but I do not think the above numbers would require material alteration. Having now fixed the critical temperature and pressure of alcohol under its own vapour, the next work consisted in determining the critical tempera- ture of the same liquid under greater pressure. When any greater pressure than the critical is used, the tube is filled with a homogeneous fluid, the two states of a fluid being impossible under such a pressure. The critical state cannot, the: ‘ore, be observed under such conditions, _as all the phenomena by which the liquid state can be recognised are dependent upon the observation of a limiting surface having a certain ¥2 304 Myr. J. B. Hannay. contractile power, and such power cannot be observed except the liquid have a free surface—that is, a surface bounded by another fluid with which it is not miscible. It was found that all liquids such as water, hydrocarbons, ethers, &c., however immiscible they may be at ordinary temperatures, mix freely or act upon one another long before the critical point of one of them is reached; therefore liquids will not serve to furnish a free surface. A gas, therefore, is the only substance which will bear any pressure without becoming miscible; and if it is insoluble in the liquid (and all liquids have some gases insoluble in them) we are provided with asubstance to overlie the liquid which will allow of a limiting surface being seen at any pressure. This was the methed used. A quantity of pure dry hydrogen was placed over the alcohol, and pressure applied, and the effect of rise of temperature observed. It was seen that when the temperature rose to the critical point the line dividing the alcohol from the mixture of alcohol vapour and hydrogen became quickly indistinct, and was replaced by a broad mark, indicating a gradual change in the refractive index of the fluid when passing the place where the liquid surface had been, showing that diffusion was taking place. On lowering the temperature before much diffusion had taken place, the point where the liquid surface had been became dim just as the temperature passed below the critical — temperature and the sharp limiting surface became re-established. The pressure was then increased by decreasing the volume of hydrogen, and the experiment repeated many times at the new pres- sure. The temperature must be raised much more slowly for these observations than for the simple observation of the critical point with alcohol alone, as in the latter case the upper and lower portions of the fluid become of the same density, instantly obliterating the line of the meniscus ; but when hydrogen is above the alcohol the line remains although the alcohol be gaseous, until it is obliterated or broadened by diffusion. Thus, on raising such a mixture to the critical temperature, it is necessary to keep the temperature steady, to ascertain whether or not diffusion will take place. If a rise of temperature is going on, the thermometers will register a higher temperature than that at which diffusion began. In this way the following series of observations were carried ont :— Table IV. Alcohol with Hydrogen. Manometers A” and C. dye Mv, t. te lee Be bie th 230 232 80 CD EPMO SM 220 288 17 17 229 229 75 FOR NREL RTE 221 or nao 20 18 231 230°5 78 COSTAR eS 219 287 21 19 On the Limit of the Liquid State. 305 rT: T’. t. t’. P: Bs i a 234°5 229°5 77 (24 ESR 219 287 Is" 16 234: 228°5 76 0) Sig eee ee 219°5 287 19 15 232 231 73 (C740 1 ae CaN 219°5 287 17 15 233 232°5 82 SOMA i Mo oars 217 2855 16 16 232 2025. @8 SO ders cs 2h 220°5 288 15 15 232 °2 232°0 79 CAO RN 219°8 287 14 14 231°5 232°5 62 (2 phe Sea eee 215°5 282°5 15°5 15 231°5 232°5 69 (Oe) Aaa ie ea ea 218°8 286 16 16 233 232 74 GA ER in atstiay: 220 28007 7 17 231°5 2382°2 72 A 219°5 288 16 15 232 Belo. fo LS) AAU a ess te 217°5 286 Ie 17 232 233°5 85 Ot ag sites te 217°5 285°5 15°5 16 233 °5 232°5 87 SOPPuN ii eheies 212 275 16 16 232 233 82 Sy eae sis 219 285 17 18 232°5 232 80 CCM Meno 218 284: 17 17 231 231°5 76 TO EMS Sone 219°5 287 15 15 231°5 232°5 76 (Ais ai anise 2195-3) 237 16 15 232 233 7o SO aka daa 221-1 288°2 17 17 231°5 2382°5 795 TSY OES Ee 223 283 19 18 229 228°5 79 SO ale ake 218°8 286°5 17 17 Zao %® 229°5 80 SOR ie meta tas 218°9 285°5 16 16 230 229 80 SOs lanier 219°2 287 16 16 231 232 77 Les otiabed ete a 218°6 286°3 16 16 231 231 78 SO ee west 3 218°5 286°2 17 17 230 230 09 CTE ON, 219°2 286°9 15°5 15°5 229 230 76 AU wih pala d 2: 219-3 287 18 17 230 229 84 SA SS Ee eae 218°S 286°5 17 17 228 228 80 SOR tay aL ack Palcved) | Paste) *O) Aly 16 230 220 80 Ose) Oe bois 218 °8 286°6 16 16 Portion of thermometer scale exposed 82° to 232°. Average T aie Corrected mean 234°°78. 33 STNG Height of mercury in manometers over tube P =0-98 atmos. Pi=0:87 sa Average P 218°89) 20-AA, pressure in atmos. Corrected! Pe O86 45 f ie 3 (8258 atmos. Probable error of mean temperature 0°°17. ‘ - pressure 0:08. From this it would appear that the critical temperature, or, at least, that temperature at which the meniscus disappears, is lowered slightly 306 Mr. J. B. Hannay. by the hydrogen gas. Further experiments were conducted to settle this point. Table V. Alcohol with Hydrogen, Thermometer D. T. fhe iz t. iP. ts 234 228 78 ie, Cs 290 15 + 232 230 82 SOs ihre ee. 291 16 232 232 75 CORY Be 290 18 251 Gat 80 CO PE aa 291 16 229 Zale ooe BA SIE eae 291 2 230 231 ae COTE! EE 292 18 231 232 72 CON Sth eee 288 17 232 Da | 79 (Sin SPA. 290 iow 230 230 81 Sisal, Wee eee 289 16 231 20 82 GO Sa e 288 135 231 231 80 1950 Pies 288 17 229 229 75 oY LA Oe oe 292 16 228 °5 228 80 O2 Rae 291 17 fig 232 231 °5 232 °5 233 231 229 234 231 Average T ery, °, 193084 Corrected mean 234°°14 Average P 290°07. Corrected pressure 183-7 atmos. Probable error of mean temperature 0°°34. 3 pressure 0-19. Table VI. Alcohol and Hydrogen. Manometers A’’ and B”. ta t. i”. BP. Be ie 231 68 Tip le se 222 ila 15 232 72 LOT. ND. 222°4 170°2 16 233 84 SOO ee s.. 223 172 17 232°5 92 90. vier he staarse 222 171 16 231 92 OAs ante <2 221°8 1695) 438 230 90 LONE rs, SORE 222 ial Lie 235 88 OO pee eee ee. 222.29) 17-2 lee 232 75 VPM ROR’ oe 223 171 4 16 Ot NT Oe OO DO Or ox or ere 232 231 ° 231 233 233 ° 231° 230 ° 231 232 233 231 ° 233 232 ox or ox Or Or On the Limit of the Liquid State. 75 78 78 78 82 80 82 82 80 80 77 77 78 78 76 76 72 74 82 80 Sd )'79 15 5) 76 78 7) 76 74 73 77 vir 72 72 78 78 78 79 iS 80 78 80 7d 78 77 75 80 ay 81 82 80 80 79 79 78 78 80 81 81 80 85 85 80 80 75 78 79 78 80 78 P. babe 222 2 eoereee 222 °2 222 °4 Spee te 222 es ones 222 ° Ree 221° eecreee eecrecee Average T 232°°16 T’ 232°-09 Average P 222-44. 99 9) Probable error of mean temperature 0°09. 9) P’170°74 ee ee ee i Corrected mean 235°°68 Pe 170 170 170 170 170 170 °2 169 °4: 169 °8 170 PAS EZ0)-6 eS, kal 170 °5 171 171 170 °8 kl LAO; 170 163s 170 170 170 170 70; 171 171 170 170° 170° 70: 171 NZL 172 “I 00 CRW ONATHODOAKS AO \ Corrected mean 122°72 atmos. 99 pressure 0-10. 308 Mr. J. B. Hannay. Table VII. Alcohol with Hydrogen. he Pe be Be P Re ie pee 230 231 75 7OVS 5 Jee ee 226 191 16 16 230°5 231 80 CORR eae 227 192 SoBe Le 231°5 232 82 SU Sore 226°6 191°4 15 15 232 232 92 agile Wan XECS 226°4 191°6 15 15 233 231 85 Be) ete’ 226 °4 191°2 15 15 232 °5 233 90 As ia es 5 226°5 191 1o:3 |e 232 231 82 (oh nh emer 4, Ben 226°2 192-2 15°5 16 229 2300. 7S iE hacia MRR a 227 19E-38 16 16 230 °5 230 76 10S 2c eee 226°8 192 16 16°5 23059 2305.) 77 fg ee et 227 191-4" To) Eee 232 230 82 Oty er 226°2 191 16 16 231 °8 232 80 COMP 2th tee 226 191-2 oes 17 230 °4 232 73 Ti ee MRS 226°4 191°4 18 17° 232°5 231°3 72 hme MEN hk 226°6 1913" i by 231 232 80 SORE sort 226°9 1S21 Ges 15 mies = ett Corrected mean 235°-04. oo 4 ata Corrected mean 178°80 atmos. Probable error of mean temperature 0°18. ts 5 pressure 0-07. From these tables we see clearly that the critical temperature is not materially altered by a very large increase of pressure ; in fact, in the last case the pressure is nearly three times as great, and yet we have only a lowering of the critical temperature by about one degree. It: was found, however, that as the pressure was increased the solubility of the hydrogen in the alcohol also increased, so that at high pressures a very considerable lowering of the critical temperature takes place. When the two fluids have thoroughly mixed at a temperature over the critical point, the passage of the mixture through the critical tempera- ture downwards is not attended with immediate liquefaction; in fact, this does not take place till a temperature 10° lower is reached, the ~ hydrogen preventing the alcohol from assuming the liquid condition. At a pressure of 250 atmospheres the meniscus disappeared, or rather became broad at 225°; but diffusion did not take place completely ; the surface seemed to be destroyed, but the action did not go deeper, while at 300 atmospheres the meniscus was lost at 220°. This is plainly owing to the action of the compressed hydrogen, and could we have a gas quite insoluble in the liquid, this lowering would not take On the Limit of the Liquid State. 309: place. It seems clear then that the temperature at which the perma- nent surface of a fluid (which constitutes liquidness) disappears is not altered by increase of pressure, and this is equivalent to saying that the critical point is the termination of an isothermal line which marks the limit of the liquid state. It next remained to be seen whether any other insoluble gas would act in the same manner as hydrogen. It must be remembered that hydrogen is furthest removed from the liquid condition and the least dense body known, and the nearer the density of the superincumbent gas approaches to the density of the liquid, the greater effect will it have upon the critical temperature. To test this, a quantity of nitrogen was placed over alcohol, and the experiment conducted simi- larly to those with hydrogen. Table VIII. Alcohol with Nitrogen. Manometer C. Ap dhe t. t. 1 Bes bie 231°5 232 78 GOR Pan 274: 16 232 231°5 77 CSG vated 267 16 231°5 231°5 78 Then Ge ea sasha 262 155 232 °5 232 80 cool Ean eran? 262 15 232 231°5 82 CO UM neee 270 15 231°5 232 80 SOR eee ae 270 15 232 °5 232 81 CHL AB cera 276 16 230 231 80 SORE ns tetas 276 17 229 230 80 (RSV GRY AEB as 276 18 231°5 232 75 TA a iON AT 278 17 231°5 231°5 76 7S ily MEN IA ec Be 277 16 232 °5 232 78 C10) on ete ee 273 15 Average T 231°:50 ‘ 1’ 9310-5 a Corrected mean temperature 235°11. Average P 271:75. Corrected mean pressure 82°35 atmos. Probable error of mean temperature 0°°22. “a a pressure 0-19. These numbers plainly show that the meniscus of alcohol disappears at the same temperature, whether under tue pressure of its own vapour or at a pressure of eighty atmospheres with nitrogen, affording further proof that the liquid state terminates at the critical temperature. Another method still remained to be tried, that of measuring the capillary height of a liquid under various pressures and temperatures. The method used at first was to fix a small piece of capillary tubing 310 Mr. J. B. Hannay. into the interior of the working tube by melting a small piece of sili- cate of soda, and causing the tube to adhere; but this was found to be disadvantageous, as the tube almost invariably burst where the silicate was adhering. The method latterly used was simply to make an obtuse-angled bend on the tube, so that the piece of capillary tube could not pass beyond this, but became wedged. The capillary height was measured by a cathetometer in the usual manner. The following table gives the results :— Table IX. Capillary Height of Alcohol. Manometers A” and B”. Ts QU Ee ye. Py: el) eee Cap. Ht. 105 103... OL = 9 19-16" 16 Yo SOR eee 34 34 16 15°5 540 ba BSB 1S-HIS-5.... ..) =) .. 67 67:15 18... a a ee $1 80:5 16-16 2.2.4. ae re 9- 90217. .17 ....0 (ol) ere 08 108 16 16 .... .44 +.) 2 12 192 «18-417 «Cd... ke ee ee 127 (127 «918..18 |... ° 136 cae oe 187 1365 20520 1... 0) 45 <== aS 4G BS 4n88 2 es Rae 16: . eee 155: 154-8 S7n087 Oa 16: . 4 166-5 1665 35° 34 ..., aia... 16°5 .... 300 eo 473. 40-240 “eee |. 17. + cee 186 - 186 53 SO” Seeeooe 17: 3 gees 12 198 60 60. ees 16°52. ie 195 195 60. Gl . xc.) 189°5. 27 16-50 eee 202 $202 65 66 .... 199 52 46-5) ame 205 205°5-70 2 ::.. 904 83 (16 > eee 209 210 70-70. 2.5 7 206). 190--, Ae 914 214 72 75 scm 9 2085107 15.) 9) 990-575 75 ....- 810, 115 iy nn 995 994578 78 .... Bi 1185 17 "a 999° 930-579 80 .... 212 199 “17 From this table curves Nos. I, fig. 2, and IX, fig. 3, have been drawn, while Table X gives the corrected values for capillary height under the pressure of alechol vapour. The numbers expressing the pressure of the vapour at temperatures below those at which the mano- meters used began to register are taken from Regnault’s observations. On the Limit of the Liquid S Erg. 2. SAN N SRRSREEEAY 312 T. P. in atmos. Cap. Ht 230M Oy ees als OEE a Ui aces ecemnme te 0 ZS0) i eas C4 Oh oe Ansan es, 40 QAM oa ta aes DOG. Moa gancden2 99 200 2 ee edie SAPO Ue ubat gs 198 TBO yi Vey eee eee Sho ei ee se 269 LOO rai eee setae LO LOU aaa o2l 1400 ees Ves fa er ee 365 millims. LAO moana’ bans Oe latte aii a2 401 LOG iia: Nraleay eae LO94C 2 Berea 436 SO aad aay (oy Dery ere) A67 OO Was cea eee ae BOs sree ghee: O01 AQ i hy Ssheee’ ae VS4e) ) aa eee 530 ZO yer cena e kee 3 BANS) i aeveanaee D009 OUR Mae vadeaten a ds Da ear ier: O79 Mr. J. B. Hannay. Table X. Curves I, Fig. 2, and IX, Fig. 3. As examples have now been given of the numbers obtained in all the different methods employed, and the probable error calculated, the tables of original numbers will be omitted and only the corrected values given, and where several observations have been made. the probable error will be given. The following table gives the capillary heights of alcohol at various temperatures under compressed hydrogen, giving a much higher pressure than the vapour alone. Table XI. Curves II, Fig. 2, and X, Fig. 3. Alcohol Capillarity under Pressure. T. P in atmos. Cap. Ht. 230) Oa aan NGS t5 st steele 0 |) Me ni fy go 12570) anda aa 63 ZOO os: | tea eee MOG OS oe: cisiateien 159 WSO oy eae aed ye (OO saan 234. TOOW se) aaa OOO) | i. wali oe 286 LAQ UI ea Eee anea Bee Oey silane 333 LAO ies ayaa aa PAT RMR MPS 372 LOO ean ees DANO 4s eens 409 SO ie ye ia 7 OI xe 8h 4.42 CO ET core aie SPs 7.08 ements A73 AQ Ser alee a a MGC a setiecire tema 503 QOS Seems eis pe ORE aia ansaid 531 Oa aan A Zhe rn 557 On the Limit of the Liquid State. 313 Table XII. Curves ITI, Fig. 2, and XI, Fig. 3. Capillary Height of Alcohol under High Pressure. T: P in atmos. Cap. Ht. EU I a DOO Omer, anon eee 0 AAO) aE = caterer DEA Oe les poy Se 26 ODE rin Salcerce oh ia. NS po eee aa ae: 129 SUE inp) Seastaresy oir TAR Sith fig fawn aes 207 GOR ee aris, SOAP iu ieee sarees 264 ‘ed0) iit he ate en JIGAS)S5 | Yin Aan seall tS 312 110) hie SL Ia Aas spay ere ast 354 BOOMER de Mistescdis oe MOO UN bse ara ene ote: 391 SL) Gm alerts SGU On missce geen: 428 Uae rte ibe. Sipe a ge aaa ah 458 NO Ra aa (510 ed Lah dra lls 489 ()) VOT Beer eae GOR Nis weace erase 517 OR aw See ves 5 CA Diy \ipfea Sislee aha 544, From these tables we see that the capillary height of the liquid is lowered by a gas under pressure impinging on its surface. Thus at 66°7 atmospheres (the critical pressure of alcohol), the capillary height falls to zero at 235°°4, at 163°5 atmospheres of pressure zero is reached at 230°°3 ; while at 236°8 atmospheres capillarity disappears at 224°°6. It is curious to note that, although the capillary action had ceased at these temperatures, the liquids had not assumed the gaseous state, as Tables IV, V, VI, VII, and VIII show that in no case up to a pres- sure of 183 atmospheres did the alcohol diffuse into the hydrogen at a temperature below 234°. As capillarity is entirely a surface phenomenon, the surface tension of a liquid seems to be weakened by the impinging of a gas under pressure upon its surface, and this we might expect to be the case, as we can imagine a constant disturbance of the surface of the liquid, owing to the high velocity of the hydrogen molecules striking it; whereas, not being soluble to any extent, few hydrogen molecules penetrate to disturb the liquidness of the interior. It would thus appear that, under such conditions, capillarity is not a true measure of the liquidness or cohesion of a fluid, and were the pressure high enough the surface of a liquid might be made to disappear, while its interier was in a truly liquid condition. This question can be most readily settled by passing a liquid, whose surface tension has thus been caused to disappear, through a capillary tube, and observing whether increase of temperature diminishes the time of flow, for the resistance of a fluid is decreased by increase of temperature, while that of a gas is increased. The experimental realisation of such a test is difficult, but apparatus is being at present constructed for the trial. 314 Mr. J. B. Hannay. In drawing out the above tables (which may exhibit slight irregu- larities) recourse was made to a large number of quite separate - observations, as full series are often difficult to obtain, owing to some failure in the apparatus when it has been in use for some time at high pressures. Hitherto only one liquid—alcohol—had been used in these experi- ments, so it was determined to try the same experiments with other liquids, and those chosen were carbon disulphide, carbon tetrachloride, and methyl alcohol. The carbon disulphide was digested over sodium for some time and distilled off pure quick-lime. This gives a liquid having no offensive odour and quite colourless. It was distilled into an apparatus similar to that used for alcohol, and preserved under a bell-jar over oil of vitriol. Four sets of observations were done in order to determine the critical temperature and pressure accurately ; in all 163 experi- ments. The results are as follows :— Mean temperature corrected...... 277°°68. Probable error of mean........ 0°16. Mean pressure corrected ........ 73°14 atmos. Probablererrorsaee ae pce eee O07 The apparatus was now arranged so that the critical temperature could be observed under pressure with hydrogen with the following results :— Mean temperature corrected...... 274°°93. iProbablelerrornacas. ob cee OL 0°:09. Mean pressure corrected ........ 171°54 atmos. Brobablexerror tocce tar pers: op 0-0 7G an For these numbers sixty-two experiments were done. Nitrogen was then substituted for the hydrogen, and the experi- ments conducted as before. Forty-one determinations were made to obtain the following means :— Mean temperature corrected...... 273°°12. Probableseror seers. 2!) a2 OF ko: Mean pressure corrected ........ 141:45 atmos. Probableyerrom ye. site oi 4s +, of 0-165. Here we see that while the pressure of the nitrogen on the carbon disulphide is much lower, the temperature at which the meniscus disappears is also lower. This is likely owing to the greater solubility of the nitrogen in the liquid, as the density makes it approach much nearer to the density of the disulphide than hydrogen. A third series was conducted with hydrogen, using, however, a much lower pressure :— On the Limit of the Liquid State. 315 Mean temperature corrected...... 20d (Oo: Propableverror’ =o. 5205: 206k 0°14. Mean pressure corrected ........ 95°86 atmos. Probableserror : 2 Pk ee. O09 Here we see only a very faint lowering of the critical point, only 0-2 of a degree, although the pressure has been increased twenty atmospheres. The capillary height of the disulphide under various conditions was next determined. The numbers gave as follows :— Table XIIT. Curves IV, Fig. 2, and XII, Fig. 3. Capillarity of Carbon Disulphide. Ah P in atmos. Cap. Ht. Za rs Se aa xslt] LOM SABES Nand ate 0 2) | a a ERS) EP ie penn Ad 24) 0 a AIS SIS S NAN mal UR 2 dete 74 OS SOM Vt se See 114 211)" he ae ae GOR eee seals ed 155 emma) es 6h ss TOAGh oes ees os 197 LSD). eee TAGES Re npn an eer te 236 5k See oh OO | Ssh eaeleks a 277 12) 2 a ea GEOR ole i SEE 316 LD) Ss eae 1S: Le a Oe 359 CU) 2 ok aera eae Dhoni 6 at ee bg ee 397 SON ere S'S Om oF. Be ste 437 2) te UGS ee ere Onerir y o ase se eee 476 ZAG at ae eae aug Na Be ie Bu 7 De a ei Sa vet doa Sait): 558 Table XIV. Curves V, Fig. 2, and XIV, Fig. 3. Capillarity of Carbon Disulphide with Hydrogen. by P in atmos. Cap. Ht. v1) a ie ee 17/5 ean ee ee N ) 25D) ON See ae MG e245 nici ihn ie 9 BUN a cuts | a ENG Oe git ayy sie oa 46 0A Se ae te Seen seen Sat ere e 84 2 REN eee WAG CD) ie sey Beara 122 1S1) 2) Sar ania Si Disiyh least ative aes 164 316 Mr. J. B. Hannay. qT. P in atmos. Cap. Ht. LOO Taped ook oe LSU Die ayes cma 203 TAO ie ee 1248) heya a eke 24.2 20 Gee Aten uae eae 278 LOO, ar ae Ae PRON eh eae Tole SOM KEE ee LOS RSG) ih Ley, 358 CON We eta OOS as a 394 AD Ay ate DOG: Ee er 434 DOA I etch eee BB io Gee ee 473 MS, Deena s CS aie he Sie eeae 515 Table XV. Curves VI, Fig. 2, and XIII, Fig. 3. Carbon Disulphide with Nitrogen. Au P in atmos. Cap. Ht. POTS a ate TOL 9 ccs Cee ) PASO) ME al AD csi LED sot a ee 23 QO 1) ye Pa 0 det OG ES i Wo Meee 61 Oi eh ee ale SS rel W Al ene ean LOOT: ZOOM \ See dete 7.5 y's Me ea dng Ll 141 TSO oy ee a Oa 8 Mout apae 197 LOOM ew crue: i yoli EU be ast. 236 TAO Ne ee ay Der Te 278 ZORA mittee Mees ve AOS) ee 317 LOO) Geen he ADEs ee 308 SOR ye aaa BOG! amen 395 BOR lene Oil), 4 (0 hea 436 AQ 48) eae BOO) aaa 478 PUM ie ele as oc 310 o's 517 OP pee 28S, eee 555 On examining these tables, and the curves which graphically repre- sent them, we see that here also the capillary action of the liquid is weakened by a gas impinging upon its surface, even at low tempera- tures, and again we see that the capillarity is reduced to zero before the liquid is really gaseous, showing that like alcohol the surface tension of carbon disulphide is destroyed by the activity of the molecules of the gas overlying it. The curve for carbon disulphide and hydro- gen, XIV, fig. 3, should not be really a straight line, but a number of accidents happened during these experiments, and the curve is made up from many readings from different manometers, that for the On the Limit of the Liquid State. 317 middle part of the curve evidently reading a little low. The whole result agrees well with what was shown from alcohol. The next body examined was methyl alcohol, a sample of ‘which was carefully purified in the same manner as the ethyl alcohol, until its boiling point was constant. It was then distilled off quick-lime into the wash-bottle arrangement for use. It gave as follows :— Mean temperature corrected...... 232°°76. Rrobablererrorsse cers eraie. Omeaile Mean pressure corrected ........ 72°85 atmos. Erobalblel errors rie acictey a oa): ‘OelZi es These means were taken from three series, each of thirty experi- ments. The same experiments were then carried out with methyl alcohol and hydrogen and nitrogen, as in the case of ethyl alcohol and carbon disulphide, yielding the following results from twenty-two experiments :— Mean temperature corrected...... 230°°14. Ibrobable: errory :. 044.5 toe 0°09. Mean pressure corrected ........ 128°60 atmos. JEAUO) TN OS CaCO ean po bh oom ye moe OAR is Here we have, as before, a slight depression of the critical tempera- ture. Hxperiments were then tried with higher pressure. Forty-seven gave the following means :— Mean temperature corrected...... 227°°92. rowableerror! gaat co es or Ocal 0: Mean pressure corrected ........ _191:40 atoms. Provable vernrons.. as sis os.5 3 shes 0:07, ax A still higher pressure was then applied. The means of eighteen experiments were— Mean temperature corrected...... 225°°82. iBrobalble error aes. sei so. 0°-26. Mean pressure corrected ........ 262°00 atmos. iPrqolop oS Claeys. Mase o aia O aI are 0090 We have a further depression of the critical point, and as the point was determined with great difficulty we have an increase of the probable error. However, the result confirms the other experiments, The same mode of experiment was then carried out with methyl alcohol and hydrogen and nitrogen as with ethyl alcohol, with the following results. VOL. X¥KIII. Z 318 Mr. J. B. Hannay. Table XVI. Curves VII, Fig. 2, and XV, Fig. 3. Capillarity of Methyl Alcohol. ds Pp Cap. Ht PAS VN are tet ie LO ge Pen ee 0 230s velar et maeies GASB) cae aoe 5 BOD. ugg cere GS eee Ree Sn tee 52 2005 Wee Dawe Oy thet Rete 133 LSOio Wore et ae DOT AOR lee tee 202 UGOP gc ce vere A Mo meaner ys. 9 257 VAC? yu os one cae dbl Oe ara Ne Symes tea 309 LAC eee yas a 0 CONE o> sitar eee 359 LOO eit rar peer Aa Bun ca eee 402 SO is decor etc: L202) SF eee AA] 60° ae 6 eee 477 AQ: ADS coe Eee tae eee 513 AQ). Ande Shed ged gl teat oie ome ee 545 Osa OU CHS. cane 0 OT eee 577 Table XVII. Curves VIII, Fig. 2, and XVI, Fig. 3. Capillarity of Methyl Alcohol under Pressure with Hydrogen. Ty iP. Cap. Ht. DA bs AE RS ca lsce L233 doris. sea 0 2A - Se ae 1 ES RY Pc ct 27 DOO Y) Sie ee esteeae U@42). os), See 106 LSO fae as 9025") asd ree LZ TOO)" 1 gee (972, eee 237 TAQ... hese 69-1. eae 287 120) serene Gl Ms RR 336 LOOPS ene yo) (0) ss See 283 SOM Mee nnn ae AS. 28 eae 4.23 GOe a" ae AQ 6 Eee 458 AO gah Ake aes BOC4 sae 493 20. tree een ne Sauce Sere 527 ONaF oat ha ae eae ORO: * ON eee 557 In these experiments we see again that increase of pressure never increases the liquidness of the fluid, and never enables it to remain liquid at a temperature above the critical point. On the Limit of the Liquid State. 319 The last liquid examined was carbon tetrachloride, and this was very carefully dried and purified by fractionation and distillation off quick-lime, the purified liquid being kept with the same precautions as were used in the other cases. It was seen, however, that the tetra- chloride acted upon the mercury, forming a white crystalline body which crystallised out as the liquid cooled. It appeared to be mercuric chloride, as it dissolved in water; but whether the crystals were pure mercuric chloride or a compound of that body with some other chloride of carbon there was not sufficient obtained to determine. The critical temperature and pressure were determined with twenty different samples, using one quantity only for two or three readings, and the following numbers were obtained :— Mean temperature corrected...... 282°°51. Pio adle Qari nese canoes aasns 0°-38. Mean pressure corrected ........ 57°57 atmos. Prebaiol enemas spss srpiscaaisea vis O14 ,, On attempting to obtain the critical temperature under pressure it was found that the hydrogen at once dissolved under pressure, and not only dissolved, but formed a compound with the tetrachloride. Some curious observations were made on the relation of pressure to chemical combination with this mixture. It was found that for a given temperature and pressure only a certain amount of combination would take place, leaving the excess of hydrogen overlying the tetra- chloride quite free. If then more pressure were applied, the mano- meter would jump up say five atmospheres, and then gradually fall about four or four and a half atmospheres, and again become stable, and this would take place each time, a large portion of hydrogen disappearing for a small permanent rise of pressure. A sudden rise of temperature had somewhat the same effect, but as the temperature could not be varied so suddenly the effect was not soobvious. Several bodies were formed by the action of the hydrogen, the action being capable of being pushed so far as to form chloroform. Nitrogen was used as a pressure substance, and it answered well. The following numbers were obtained from twenty-seven experiments :— Mean temperature corrected...... 277°°56. Heit WIORCTEON (eas sie alloyey 3204 whose condition is also determined by both pressure and temperature. The gaseous state is the only one which is not affected by pressure alone, or in which the molecular velocity is so high that the collisions cause a rebound of sufficient energy to prevent grouping. Another distinction between the gaseous and vaporous states is that the former is capable of acting as a solvent of solids, whereas the latter is not. The two conclusions arrived at from this work are— ist. The liquid state has a limit which is an isothermal passing through the critical point. 2nd, The vaporous state can be clearly defined as a distinct state of matter. To the original distinction between these two states given by Andrews—namely, that of condensibility—I have added another, that of solvent power. A vapour over a liquid holding a coloured solid in solution is colourless, but on passing the critical temperature the whole becomes coloured. In some cases, however, the solid is deposited and redissolved as the temperature rises, showing that the more per- fectly gaseous the greater the solvent power. Andrews’s distinction compels us to travel along an isotherm, mine requires high pressure ; both are thus arbitrary, requiring given conditions, but this is the case with many of the other distinctions used in science. My thanks are due to my assistant, Mr. Ewing McConechy, for his’ assiduous aid during the above described investigation. ho b> VOL. XXXII. 322 Lieut.-Col. A. Mannheim. [ Feb. 2, February 2, 1882. THE PRESIDENT (followed by THE TREASURER) in the Chair. The Presents received were laid on the table, and thanks ordered for them. Mr. Henry Francis Blanford (elected 1880) was admitted into the ‘Society. The following Papers were read :— I. “Sur les Surfaces Homofocales du Second Ordre.” By Lieut.-Colonel A. MANNHEIM, Professor in the Ecole Poly- technique. Communicated by Dr. Hirst, F.R.S. Received January 19, 1882. Un ellipsoide (O) étant donné, on sait que par un point queleonque de l’espace, on peut faire passer trois surfaces du second ordre qui lui sont homofocales. a connaissance de lellipsoide (O) entrainant la connaissance de ces surfaces homofocales, il existe des haisons géo- métriques entre (O) et ces surfaces. Je me propose d’établir, parmi ces liaisons, celles qui permettent d’obtenir les rayons de courbure principaux des trois surfaces homo- focales. Pour cela, j’appliquerai d’abord un théoréme, que j’ai eu -Vhonneur de communiquer a la Société Royale (séance du 16 Juin, 1881) et dont je vais rappeler l’énoncé : Un angle de grandeur constante, circonscrit a un ellipsoide donné et dont le plan est normal a cette surface en chacun des points de contact des cotés de cet angle, se déplace de fagon que son sommet reste sur l’ellipsoide (E) homofocal a Tellipsoide donné: ce sommet décrit une ligne de cour- bure de (E). Appelons c le sommet de l’angle mobile, ¢ a, ¢ b, ses deux cotés et a et 6 les points de contact de ces cdtés avec l’ellipsoide (O). L’angle ac b nest autre que l’une des sections principales du cone circonscrit a lellipsoide (O) et dont le sommet est c. 1 ]’on prend un ellipsoide homofocal a (O) et si on lui circonscrit de méme un cone de sommet c, on sait que le plan de l’angle ac 6 est aussi le plan d’une des sections principales de ce cone. Appelons c a’, c b', les génératrices qui forment cette section princi- pale. On peut de méme considérer une suite d’ellipsoides homofocaux a (O) et lon aura pour chacun d’eux des droites telles que c a, € 8, 1882.| Sur les Surfaces Homofocales du Second Ordre. 323 ¢a',cb', &c. D’apres ce que nous venons de pare toutes ces droites Bont ae le méme plan, ac b. Par le point ¢ (fig. 1), élevons la droite G egeann me eee au planacb. Les droites ¢ a, c b, G forment un triédre, que nous allons entrainer en méme temps que l’angle ac 6 et qui reste de grandeur invariable pendant le déplacement de cet angle. la droite G, ainsi entrainée, reste tangente en son point c a la ligne de courbure E décrite par ce point. La caractéristique du plan de la face (¢ a, G) est la droite ¢ a, car cette droite passe par les points ot cette face touche H et l’ellipsoide (O). Le lieu des positions du cété ca est alors la surface développable enveloppe du plan (¢ a, G). Nous appellerons (a) la courbe, lieu des points de contact, tels que a, de cette surface développable et de (QO). Prenons cette courbe (a) comme directrice d’une normalie a Vellipsoide donné. Pendant le déplacement du triédre le plan ac b contient successivement une génératrice de cette normalie. Sa caractéristique passe alors par le point a, ot il touche cette normalie. Mais la tangente en a a (a) et la tangente a ¢ sont deux tangentes conjuguées relativement a (O); le plan ac 0 est alors un plan central de la normalie et le point a est le point central pour la génératrice a a de cette surface. Le point « est aussi le centre de courbure de la courbe de contour apparent de l’ellipsoide (O) projeté du point ¢ sur un plan mené en @ perpendiculairement ac a.* De méme, en considérant des ellipsoides homofocaux a l’ellipsoide (O) on aura pour les points a’, a”... . des centres de courbure 2’, «’ .... tels que «. Tous ces points sont aussi sur la caractéristique du plan a c 0, c’est-a-dire qwils appartien- nent a4 une méme droite. Ce que nous venons de dire est applicable aux centres de courbure correspondant aux points b’, b” . . . . tels que b, Nous avons alors ce théoreme : Les centres de courbure des courbes de contour apparent dune suite del- lipsoides homofocaux, projetés coniquement d’un méme point c sur des plans issus des points a,a’ ....b,b ... . et perpendiculaires respec- tivement aue tangentesca,ca’....cb,ch'.... qui sont dans un méme plan doublement normal a ces ellipsoides, appartiennent & une méme drotte. Nous appellerons 1 cette droite (fig. 1). Puisque la droite 1 est la caractéristique du plan mobile a c b, et que ce plan reste constam- ment normal a la courbe H, nous voyons que : | La droite 1 est Vaxe de courbure de la courbe HK. Ht alors :— Le point y,, ou elle rencontre la normale en c & Vellipsoide (FE) est lun des centres de courbure principaux de cette surface. * Voir mon “ Cours de Géométrie Descriptive,” p. 300 et suivantes. aed Ne SU) bo pee Lieut.-Col. A. Mannheim. [Feb. 2, Kies 1. La courbe E est intersection de cet ellipsoide et d’un hyperboloide homofocal (D). La droite 1 rencontre alors la normale en c a cet hyper- boloide en un point 6, qui est un centre de courbure principal de cet hyperbolotde. Nous n’avons considéré jusqu’a présent que langle a ¢ b, section principale du cone de sommet ¢ circonscrit a l’ellipsoide (O). Prenons maintenant l’autre section principale, a, c b,, de ce coOne et supposons qu’on déplace le sommet ¢ sur l’ellipsoide (H), de facon que l’angle a, ¢ b, reste de grandeur constante ; le plan de cet angle restant toujours doublement normal a cet ellipsoide. Le sommet ¢ décrit alors sur (K) la ligne de courbure KH’ de cette surface et en raisonnant comme pré- cédemment nous déterminons la droite 2, axe de courbure de E!. La droite 2 rencontre au point y la normale en c a Vellipsoide (EK), et au point n, la normale en c a Vhyperboloide (H) homofocal a (O), et qui coupe (E) suivant la ligne de courbure EH’. Les points y2 et 4, sont des centres de courbure principaux. Au moyen des droites 1 et 2 nous avons donc déterminé les deux centres de courbure principaux 4, 72 de l’ellipsoide (#), et le probleme de la détermination des éléments de courbure de cette surface est ainsi acheve. Tl n’en est pas de méme pour les hyperboloides (D) et (H). Pour chacune de ces surfaces nous n’avons encore déterminé qu’un seul centre de courbure principal: occupons nous maintenant de déterminer les deux autres. L’illustre Chasles, dans son Réswmé d’une théorie des surfaces du 1882. ] Sur les Surfaces Homofocales du Second Ordre. 325 second ordre homofocales,* est arrivé au théoreme suivant, qu’il énonce ainsi : Htant données deux surfaces homofocales A et A’; si on leur circonsertt deux cones ayant le méme sommet: la courbe de contact de la surface A sera la focale dune surface inscrite dans A’ suivant la courbe de contact de celle-ci. Appelons (S) la surface ainsi inscrite dans A’ et menons par le sommet du cone un plan sécant. la section faite dans (S) par ce plan est doublement tangente a la section faite dans A’ par ce méme plan. Ceci est vrai, quel que soit le plan sécant ; il en résulte, lorsque le sommet du céne vient sur A’, que: Si Von a une surface du second ordre A et un céne qui lui soit circon- scrit, la surface du second ordre (S), qui a pour focale la courbe de con- tact de A et de ce cone, et qui est tangente aw sommet de ce cone a une surface homofocale a A, a, avec cette surface en ce point, wn contact dw troisiéme ordre. Supposons que le sommet du cdne soit dans l’un des plans prin- paux de A; la courbe de contact de A et de ce cdne, c’est-a-dire la focale de (S), est alors rencontrée normalement par ce plan principal ; ces points de rencontre avec ce plan principal sont alors les foyers de la section faite dans (S) parce plan. Nous sommes alors amenés au théoréeme suivant, qui a déja été énoncé ainsi par M. Faure.t Deux coniques homofocales étant données, si, Wun point m de lune, on méme deux tangentes a Vautre et que Von trace une conique passant par le point m et ayant pour foyers ces points de contact, elle aura avec la premiere un contact du troisiéme ordre au point m. Reprenons maintenant lellipsoide (O) et l’ellipsoide (E) qui lui est homofoceal. Projetous ces surfaces sur le plan (a cb) qui est le plan d’une section principale de (E). En vertu d’un théoréme connu, les henes de contour apparent de (O) et de (E) sur ce plan sont deux courbes homofocales. Mais la ligne de contour apparent de (EH) a, pour rayon de courbure en ¢, le rayon de courbure principal, cy, de (EH): on aura donc ce rayon cy, en appliquant le théoreme de Faure. Voicila construction qui, sur le plan (a cb) donne ce rayon de cour- bure: au point a on éléve une perpendiculaire 4 ac. Du point ou cette droite rencontre la normale cy, on éléve une perpendiculaire a cette normale. Cette perpendiculaire rencontre ¢ a en un point que Pon joint par une droite au point obtenu de la méme maniére sur ¢ 0; cette droite rencontre la normale cy, au point yz qui est le centre de courbure cherché. On construit de la méme maniére sur la normale cé, le centre de * “ Comptes Rendus des Séances de l’Académie des Sciences.” Séances des 11 et 18 Juin, 1860. + “ Recueil de Théorémes relatifs aux Sections Coniques.”” Par M. H. Faure. (Paris: Gauthier-Villars. 1867.) 326 Lieut.-Col. A. Mannheim. [Feb. 2,. courbure 6, de l’hyperbole qui a pour foyers a et b, et qui passe par le point c. Ce point 6, est un centre de courbure principal de I’hyper- boloide (D). En faisant usage des points a, b,, on retrouve le centre de courbure qy, et on détermine sur la normale cy, le centre de courbure principal n2 de V’hyperboloide (H). Nous avons done déterminé les centres de courbure principaux 62, y2: qui nous restaient a trouver. La droite 62, 42 est Vaxe de courbure de la courbe d’intersection D des deux hyperboloides (D) et (H). Comme on a pu le remarquer, en méme temps que nous déterminions les points 6, 7, nous avons retrouvé les centres de courbure principaux de l’ellipsoide (K). Ces points ¥, Y2 établissent donc une liaison entre les constructions résuitant des deux théoremes absolument différents d’ou nous sommes partis. Vérifions directement cette liaison et pour cela démontrons deux lemmes. On donne un angle mcn (fig. 2) et wn point five i de sa bissec- trice. Par le point i ow mene la transversale m un et des points m, n, on éléve respectivement des perpendiculaires aux cotés de Vangle. Ces per- re esas rencontrent la bissectrice auw pownts m’, n’: le conjugue harmonique VY de c, par rapport a m’, n’ est le méme quelle que sout la transversale m n. ee Pen Costa: En effet, on a a a eee cm cn 7) en appelant « la moitié de ’angle donné. TI] résulte de la: 1 i i 2? cosa i - > cm’ cos.a cn’ COS.a Ch don 1 a 1 2cos’a cm cn’ CL ‘ : ee a Mais le premier membre de cette égalité est égal 4 —, on a donc ct - Ct COS? x Cette valeur de ¢:’ étant indépendante de la direction de m n, le lemme est démontré. On donne deux angles men,m'’cn” (fig. 2) ayant méme sommet c et méme bissectrice ci. Du point five 1 on mene une transversale m n que rencontre les cétés de Vun des angles en m, n. De ces points on eéléve respectivement &@ ces cdtés les perpendiculaires mm’, nn”. Ces droites rencontrent les cétés du second angle en m,n”: la droite m” n coupe la 1882.| Sur les Surfaces Homofocales du Second Ordre. 327 Fia. 2. bissectrice ci en un point i’ qui reste fixe, lorsque m n tourne autour de 1. 9 En effet, on a: eer eaC0S @ cm cn Ct Vor sala ta COS @ . COS G58) tt / ° Civ Cn CL en appelant f la moitié de langle men". BOs On a Mais le premier membre de cette égalité est égal 4 —— cl ae 1 oes a cos (2—B) Gi, cu. cos B Cette valeur de ci’ étant indépendante de la direction de m n, le second lemme est démontré. Reprenons le céne circonscrit a(O) et dont le sommet est ¢ (fig. 1). Appelons / le point ot le plan (a 6, a, b,) rencontre la normale cy. Faisons tourner le plan a, cb, autour de c J pour le faire coincider avec le planacd. Désignons par wlanglel ca et par w, langle 1c a,; nous supposerons w plus grand que w,. Ainsi amenés en coincidence les angles a¢ b, a, ¢ 6, forment, sur le plan a c 0b, une figure analogue a la figure (2). Il résulte du second lemme que le centre de courbure y, peut s’obtenir, comme précédemment, en menant sur le plana c b et par le point / une droite quelconque. Prenons alors la transversale menée par le point J perpendiculairement 4c J. Cette droite rencontre les cdtés de langle ac b aux extrémités du grand axe de l’ellipse qui 328 Lieut.-Col. A. Mannheim. [Feb. 2, résulte de lintersection du cdne et d’un plan, issu du point / et per- pendiculaire 4c J. Appelons (J) cette ellipse de centre I. Les demi-axes de l’ellipse sont égaux acl tang w, cl tang w,. Le rayon de courbure p de cette courbe a l’extrémité du grand axe est alors égal a cl tang? w, tang w D’apreés le second lemme le centre de courbure principal du cone correspondant a l’extrémité du grand axe de (J) se projette sur c/ au point y,* On a alors ey, =cl+ly,=cl+ p tang w, et en introduisant la valeur de p, il vient : cl On saa COS? w) Mais cette valeur de cy,, on Vobtient directement d’apres le premier lemme en prenant la section principale a,c b,; la vérification que nous nous proposions de faire est donc achevée. Nous avons en outre les expressions des rayons de courbure princi- paux des surfaces homofocales 4 (QO), ainsi: cl cl (Gia) 9— oa Gy COS” w, cosa Ci as De la méme maniére en appelant /’ et J” les points de rencontre du plan (ab, a, b,) avec les normales co), cy, on a: ol! Cli Gea) O09 Se sln~ w SIN” Ww Pour déterminer co, et cy,, nous n’avons qu’a considérer le demi- angle compris entre les asymptotes de l’ellipse (1). Appelons @ cet angle. Ona: SIP eye? 2 ete —c* tang’ «,____ tang? w, F: e) cl tang? w tang” w tang? w d’ou cos? d= . Ss" ae tang” w— tang’ w, et par suite 08 __cl’ (tang? w— tang? w,) or __ cl’ (tang? w—tang? w,) TS 2a ipa or Py 2 ak tang” w tang’ w) Il faut remarquer que 6, et le point /’ sont par rapport 4c d’un- méme coté sur la normale cl’, et que le centre de courbure 6, est de coté different si nous supposons que 6, et 6, soient les centres de cour- * Cette perpendiculaire a cl qui donne le point y,; remplace la droite 1, dont nous avons parlé précédemment. 1882.] Sur les Surfaces Homofocales du Second Ordre. 329 bure principaux de l’hyperboloide 4 une nappe (D) qui est une surface 4 courbures opposées. Au moyen de ces valeurs, on vérifie tout de suite le théoréme de Lamé qui consiste en ce que le produit cy, X cb, X cn, est egal a moins le produtt CX 66, X Cn. Puisque les rayons de courbure principaux cy, cy, ne dépendent que du segment cl et des angles compris entre les génératrices qui forment les sections principales du cone de sommet ¢, on a le théoreme suivant : On donne un cone du second ordre de sommet c, un point | sur Pun de ses axes, et parce point on méne un plan arbitraire qui coupe le cone suivant une certaine courbe. Le long de cette courbe on inscrit dans le cone une surface du second ordre quelconque, et Von construit la surface homofocale a celle-ci qui passe en c et qui a pour normale en ce point la droite cl. Cette surface et toutes les surfaces analogues, que lon obtient en faisant varier le plan sécant mené par | et les surfaces du second ordre inscrites, sont osculatrices entr’elles au pornt c. Reprenons la ligne de courbure E de Vellipsoide (11), cette hgne étant le lieu du sommet de langle constant ac, il résulte de lex- pression de cy, que: Les rayons de courbure tels que cy. des sections faites dans (K) par des plans normaux a EK sont proportionnels awa segments tels que cl. La ligne de courbure E peut étre engendrée, comme nous l’avons dit en commengant, en employant l’un quelconque des ellipsoides homo- focaux 4 (O). Parmi ceux-ci nous pouvons prendre celui qui, limité a Vellipse focale de (EK), est infiniment aplati et appliquer le résultat précédent. Nous voyons alors que: Les rayons de courbure, tels que cry, des sections faites dans (H) par des plans normaux a EK sont proportionnels aux segments compris sur ces rayons entre les points de HK et les points ow ces rayons rencontrent le plum de Vellipse focale de (E). Comme les plans principaux d’un ellipsoide déterminent sur une normale quelconque de cette surface des segments proportionnels, on peut remplacer dans cet énoncé le plan de ellipse focale par un quel- conque des plans principaue de l’ellipsoide. Appelons 7 le point ou la normale c¢/ rencontre le plan de ellipse focale de (EH). Puisque les rayons de courbure tels que cy, pour les points de E sont proportionnels a cl et a cn, ces segments sont pro- portionnels entr’eux. Ona alors ce théoreme : Les normales & (E), tsswes des points de H, sont partagées par les plans polaires de ces points pris par rapport a des ellipsoides homofocaw: a (BH), en segments proportionnels. Cherchons comment varient pour les points de H les rayons de cour- bure, tels que cy,, des sections faites dans (EH) par des plans normaux a cette surface et tangents a H. 330 Sur les Surfaces Homofocales du Second Ordre. [Feb. 2, On sait, depuis: Dupin,* que le produit des rayons de courbure principaux en un point d’une surface de second ordre est inverse- ment proportionnel 4 la quatrieme puissance de la distance du centre de la surface au plan tangent en ce point. Appelons o p la perpendiculaire abaissée de o sur le plan tangent en const* op* Kt comme le produit op x cn=const®, on a donc ca(H). Onaalors ey, X cy,.= Cr, X Cy2=const® x ent. Mais pour les points de EH les rayons de courbure tels que cy: sont proportionnels 4 ¢n; d’apres cela nous retrouvons ce théoreéme connu. Les rayons de courbure, tels que c y, des sections faites dans K par des plans normaux a cette surface et tangents a H, sont proportionnels aw cube des normales issues des points de cette courbe.¢ cl : : Ht comme — est constant pour les points de H, nous ajoutons : cn Ces rayons de courbure sont aussi proportionnels aux cubes des segments tels que cl. D’apres cela on peut écrire : cl vin ~—_= const X cl’, COS” w, d’ou cl X cosw,;=const®. Ainsi: Les projections des segments tels que c 1 sur les drovtes telles que ¢ ay, sont de grandeur constante, quelle que sort la position de c sur H. La ligne de courbure E peut étre prise dans lun des plans princi- paux de (H); on voit ainsi que ce théoreme s’applique 4 deux coniques homofocales. Prenons arbitrairement un ellipsoide homofocal a (O). Soit, dans le plan a, c b, la genératrice ¢ a, du cone de sommet ¢ qui est circonscrit a cette surface. Ona el cl, ON ee ae TG) 9 Cos” Q) COS” Wy en appelant ¢ 1, et w, les éléments relatifs 4 cette surface et qui sont analogues 4 cl et w,. Mais cl, est proportionnelle 4 cn. Donec le rapport ~ est constant pour les points de EH. On voit alors que OA cos “1 =const®; ou en prenant les compléments des angles: COS Wp) * “ Développements de Géométrie,” p. 212. + De ce théoréme résulte facilement que:—Les lignes de contour apparent de (¥), projeté orthogonalement sur des plans normaux a cette surface et tangents a Hi, sont des ellipses de méme aire. 1882. | On Measuring the Thermal Intensity of the Sun. ddl Les droites telles que c¢ aj, € a, font avec le plan tangent enc a (HK) des angles dont le rapport des sinus est constant, quelle que soit la position de c sur Hi. Ce théoréme étant vrai pour la ligne de courbure de (i), qui est dans l’un des plans principaux de cette surface, s’applique a des coniques homofocales ; par conséquent : Hiant données trois coniques homofocales, si d’un point c de Vune, on mene une tangente a chacune des deux autres: le rapport des sinus des angles, que ces tangentes font avec la tangente en c a la premiere, est con- stant, quelle que soit la position de c sur cette courbe. Voici encore un moyen de faire voir comment sont liés entr’eux les centres de courbure principaux des trois surfaces homofocales a (O) qui passent par ¢. Dans le plan (a ¢ b) les points yz et 6, sont les centres de courbure de deux coniques qui ont pour foyers les points a et b, et qui passent pare. On sait alors* que le point 6,, relatif a une de ses courbes, est le pole de la droite ¢ y, par rapport a autre courbe. II] résulte de la que la droite y. 6, est perpendiculaire 4 la droite qu’on obtient en prenant la symétrique, par rapport 4 ¢ y2, de la projection du diamétre oc sur le plan (ac b).+ De méme pour la droite 1, ¢,, elle est perpendiculaire au symétrique, par rapport a la normale ¢ J, de la projection sur le plan a,c b, du méme diametre oc. On peut alors dire: Les droites y 6, Yq %, sont perpendiculaires a la direction suivant laquelle le diamétre o c serait réfléchi en c si la surface (E) était réfle- chissante. II. “On Measuring the relative Thermal Intensity of the Sun, and on a Self-Registering Instrument for that Purpose.” By EH. FRANKLAND, D.C.L.,F.R.S. Received January 24, 1882. 7 The thermometric estimation of relative solar intensity, according to the best known means, requires first the determination of the temperature of the air—so-called shade temperature—and secondly, and simultaneously, that of a. thermometer with a blackened bulb placed i vacuo in the sunshine—sun temperature: the difference * Voir “ Treatise on Conic Sections.” By Rey..G. Salmon. (6th edition, p. 56.) + Pour arriver a ce résultat, il suffit d’appliquer au point 6,-de la tangente cd., ce théoréme di a M. Ribaucour :—“ D’un point m, pris arbitrairement sur la tangente- en ¢ 4 une conique, on abaisse des perpendiculaires sur la polaire de m et sur le dia- métre aboutissant en ¢, elles interceptent, sur la normale en c, un segment égal au rayon de courbure en ce point.” 332 Dr. E. Frankland. On Measuring the [Hebaz, between the two temperatures being taken as a measure of the sun’s radiant heat operating at the time and place of the two observations. The chief sources of error in this method are the difficulty of ascertaining the temperature of the air immediately surrounding the vacuous globe containing the blackened bulb, and the placing of this thermometer under exactly similar conditions at different meteoro- logical stations. How considerable may be the errors arising from these sources will be evident from the following observations and experimental results. Determination of Shade Temperature. A thermometer merely shaded from the sun gives, in air of uniform temperature, readings differing very widely from each other according to its surroundings. If it be placed opposite a wall, for instance, upon which the sun is shining, the temperature indicated will be several degrees above what it would be if there were no such object near. I have also observed a difference in its readings when, on the one hand, it is exposed towards a blue sky, or, on the other, towards white clouds. Again, if the thermometer be placed in a !ouvred box, the readings will be much too high, unless the outside of the box be white; because the box becomes heated by the sun and communicates its heat to the air entering the louvres. Even the colour of the ground beneath the box has considerable influence upon the temperature of the air inside. A. true shade temperature means the temperature of free air in full sunshine; and, strictly, it ought to be ascertained without any shade at all, for, as soon as a shade is created, conditions supervene which often entirely baffle the object of the observer. ‘The shade of a parasol exhibits a different temperature from the shade of a tree, and this again differs widely from that of a house. The temperature of the shade of a sheet of tinfoil is quite different from that of a sheet of writing-paper. Indeed, it may be truly said that every shade has its own peculiar temperature. The following thermometric readings show this effect of the area of shade, and of the quality of the shading material :— Shade Temperatures. Beneath larch tree eee. a. eee IRS (C., 7 White parasol)... 6... eee 25°0 : small white paper arch........ 30°0 oF small arch of bright tinfoil.... 40:2 Thus shade temperatures, measured during 1? hours of uninter- rupted sunshine in the middle of the day, and within a few yards of the same spot, differed by no less than 25°°7C. These observations 1882.] relative Thermal Intensity of the Sun. 333 were, however, made at Pontresina, 5,915 feet above sea level, and so wide a range would probably not occur at lower altitudes. The most effective shading material is, obviously, that which most perfectly reflects solar heat; and of all materials with which I have experimented white paper is the best, white linen and zinc-white being nearly equal to it. The most trustworthy shade thermometer, there- fore, is one having its bulb covered with a thin Jayer of white paper, or, in default of this, the naked bulb may be shaded by a small arch of white paper. So placed, the thermometer will indicate a lower temperature than any obtainable in a similar shade produced by any other material. The foregoing temperatures were observed when the thermometer was level with the ground, but the readings often rapidly become ‘lower as the instrument is raised. The ratio of the diminution of temperature at increasing heights above the ground is, during sun- shine, enormously great within a few feet of the earth. The ground, stronely heated by the sun, powerfully warms the molecules of air in immediate contact with it; these, becoming specifically lighter, rise, and at once begin to share their heat with the colder molecules above them, losing temperature in proportion as they mix with larger and larger volumes of supernatant cold air. The intensity of this effect attains a maximum when the air is calm, and a minimum during a storm. Indeed, these powerful convection currents are readily seen, on a calm sunny day, rising from the ground like the heated air from a stove, but they are scarcely, if at all, visible when a strong breeze is blowing. In order to be comparable with each other, therefore, observations of shade temperature, whether at the same place or at different stations, should always be made under uniform conditions. That is to say, the thermometers, fully exposed to the air, should be similarly protected from radiant heat, and should be placed either at the level of the ground or at a definite height above it, upon a surface of uniform quality as regards absorbing and reflecting power. I would suggest that the bulb of the thermometer and 2 inches of its stem should be protected from the rain by being placed beneath a sheet- zinc arch of l-inch span and 4 inches long, painted inside and out with “ flatted ” zinc-white. The instrument with the arch should be securely fixed horizontally upon a wooden stand 1 foot square, painted on both sides with “flatted ’’ zinc-white, and, in order to avoid the excessively warm air very near the ground, the stand should have a height of 4 feet—an elevation convenient for observation, and one at which the temperature of the air suffers comparatively small decre- ments per foot of elevation. It should also be at a distance from buildings or trees, and have as free a horizon as possible. By the use of instruments so prepared and mounted, comparative and fairly ry (SU) 34 Dr, E. Frankland. On Measuring the [Feb. 2, trustworthy determinations of air or shade temperatures in different localities would be obtained. Determination of Sun Temperature. The term sun temperature, as commonly employed, has a very vague meaning. If a body could be placed in sunlight under such circumstances as to absorb heat rays and emit none, its temperature would soon rise to that of the sun itself. But as all good absorbers of heat are also good radiators, the elevation of temperature caused by the exposure of even good absorbers to sunlight is comparatively small. Thus an isolated thermometer, with blackened glass bulb, placed in sunshine, will rarely rise more than 10° C. above the tem- perature which it marks when screened from direct sunlight. Under these circumstances, however, the thermometer loses heat not merely by radiation, but also by actual contact with the surrounding cold air. If the latter source of loss be obviated a much higher sun temperature is obtained; thus, the blackened bulb inclosed in a vacuous clear glass globe will sometimes, when placed in sunlight, rise as much as 60° C. above the shade temperature, and a still higher degree of heat may be obtained by exposing to the sun’s rays the naked blackened bulb of a thermometer inclosed in a wooden box padded with black cloth, and closed by a lid of clear plate glass. Thus I obtained with such a box, on the 22nd of December, in Switzerland,* when the air was con- siderably below the freezing point, a temperature of 105° C., and a still higher temperature could doubtless be obtained by surrounding the thermometer with a vacuous globe before inclosing it in the padded box. These widely different temperatures, produced under different conditions by the solar rays, show that such observations can be com- parative only when the thermometer employed to measure them is always surrounded by the same conditions. Under these equal con- ditions, however, the relative solar intensities at different times or places, are expressed by the number of degrees through which the sun’s rays can raise the temperature of any body—the bulb of a thermometer, for instance—above that of the surrounding. air. Various instruments have been contrived for such measurements, but the thermometer with blackened bulb in vacuo is the most con- venient. As indications of solar intensity, however, its readings are, as I shall proceed to show, of little value if, as is sometimes the case, the instrument be simply placed upon grass, or if the shade temperature be not determined in immediate proximity to the vacuous bulb. The following experiments, made with a blackened bulb 7m vacuo verified at Kew Observatory, show how dependent upon the nature of the surface beneath it are the indications of this instrument. They were all made when the thermometer was placed * “ Proc. Roy. Soc.,” yol. 22, p. 319. 1882. | relative Thermal Intensity of the Sun. j00 horizontally with the stem at right angles to the direction of the sun’s rays, and sufficient time was always allowed for the thermometer to assume its proper temperature before each reading was taken. Tosten Vierod, near Laurwig, Norway. July 17th. Brilliant sunshine, cloudless sky, strong breeze. Time. Position of thermometer. Temperature. SSOEN ai. OM, OREN STAGE: = oo « « oieie + ors. 0,5 0-0 57°3° C. 10.10 ,, .. On somewhat parched grass...... 61:2 ees. Om are SOM 575 racks, sous e = «0,6, oe ace 60°6 11.10 ,, .. On staff 5 feet above meadow.... 50°5 11.40 ,, .. On newly-mown grass .......... 56°95 Poet) Me On white paper. 2.2... s+... (30 ete On, staf asa LLLO ee te 51-5 Wilhelmshoéhe, Hesse Cassel. Time llam.tol pm. August 16th. Brilliant sunshine. Position of thermometer. Temperature. On staff 5 feet above grass ........ me Se (C: @utblack-caoutchouc’.. ... 5.2.54. 54°7 Mnbwyiibe Aer so. ser. ss < <'s = > + 0 Ss 68°7 Dm lass mirror ysis e <2 fe.s 242 + ee 64:0 myrmolackastiicn Mors awe cores eerie 56°5 On slightly concave metallic mirror.. 640 ERAS rsks She farsi 2:o2e 8 n'a s sss em #0) = 6 58°5 Pontresina, Switzerland. September 7th. Clear and cloudless sky; breeze. Time. Position of thermometer. Temperature. 1.10 p.m..On staff 4 feet above ice of Morta- PALS Me Gwlacier |S Fico 3.2 lac8's J's) 43°9° C. 1.30 ,, .. Onblack caoutchouc laid upon glacier 39°0 ee. . On barenee or glacier ..o. 2s... <) 475 2.30 ,, ..On white paper laid upon glacier .. 53°0 Summit of Diavolezza Pass, Switzerland. September 8th. Clear and cloudless except on horizon. Time. Position of thermometer. Temperature. 10.30 a.m..On staff 4 feet above snow........ 48°6° C. 11.0 ,, ..On black caoutchouc laid upon snow 39:1 pee As UCN STOW. 4s: oha''sisa e -ASedoiatciaeei oars 61:9 12.0 noon. On white paper laid upon snow .. 65°5 306 Dr. E. Frankland. On Measuring the [Feb. 2, Bellagio, Italy. ‘ September 17th. Clear sky except near horizon. Air very moist and calm. Time. Position of thermometer. Temperature. 10.30 a.m.. On black caoutchouce laid upon grass 60:0° C. 1045). .0On blackmerimos aguas eee 59°0 YS: 5. On! whitterpaperm. si9-c-)s. cues tei 66°3 11.30..,;, “2 Onuwhute limenwrr ere see cree 66:0 In some observatories, the blackened bulb in vacuo is laid upon grass ; but the experiments at Tosten Vierod show that its indications vary, under the same insolation, as much as 4°°7 C. according to the con- dition of the grass; somewhat parched, and consequently lighter coloured grass, giving a higher temperature than green and mode- rately long grass, whilst the latter raises the thermometer more than newly-mown grass. These differences result partly from differences of shade or air temperature in the immediate neighbourhood of the vacuous globe of the thermometer, and partly from the different reflecting power of the subjacent surface. With regard to the first of these causes, it must be borne in mind that the solar intensity is measured by the number of degrees through which the blackened bulb in vacuo is raised above the temperature of the medium imme- diately surrounding the vacuous globe. If this medium becomes warmer, the temperature of the blackened bulb will rise in a corre- sponding measure, and vice versd, although the solar intensity remain the same. Now, the more absorbent the surface upon which the sun’s rays fall, the higher, ceteris paribus, will be the temperature of the air resting upon that surface. Thus, with the same solar intensity, the shade or air temperature on white paper was -25°°2 C., on black caoutchouc 28°°5 C., on short grass 22°77 C., and upon a rock 22°°6 C.; whilst at a height of 4 feet above the grass it was only WESC It is to the second of the causes just specified, however—the dif- ferent reflecting power of the subjacent surface—that the variations of the sun thermometer under the same solar radiation are mainly due, as is proved by the following observations, in which the shade temperature was always taken under a small paper arch close to the vacuous globe :— Suburb of Zurich. September 19th. Indicated Position of Sun Shade solar Time. thermometer. temperature. temperature. intensity. 11.0 am... Four feet above meadow. 47°3° C. .. 20:5°C.2. 26:35C8 11.20...) to! Oniorase Geena ae 53a J Dos fkN aeORD 11.30 ,, ..., Om white papers ..ae-4. 67:0 Da 2b30 x PAG 12.0 noon.. On black cacutchouc ... 59:0 we 270 wS2kO 1882.] relative Thermal Intensity of the Sun. Bry | These results show that the indications of the black bulb in vacuo are profoundly affected by the character of the surface beneath the instrument, the more perfect the reflecting power of that surface, other things equal, the higher the solar intensity indicated. Of all the substances tried, the highly reflecting power of white paper and linen for solar heat was very remarkable. exceeding appreciably that of bright metals, and even of freshly-fallen snow of dazzling white- ness. Of course, lateral reflection produces the same effect, and I found that the indicated solar intensity was increased by no less than 11° C. when the blackened bulb in vacuo was placed at a distance of 10 feet in front of a whitewashed wall upon which the sun was shining. Finally the indications of the solar thermometer are also affected by strong wind, the readings of solar intensity being somewhat lower when the instrument is exposed to the current than when it is sheltered. The cause of this is obvious; the difference of tempera- ture produced by the sun’s radiant heat is really that between the inner blackened bulb and the glass of the vacuous globe. Now the latter is constantly receiving and absorbing obscure rays of heat from the blackened bulb, and its temperature must therefore always be ‘somewhat higher than that of the surrounding air, which is measured by the shade-thermometer; but the glass globe will obviously main- tain a less elevated temperature when it receives the strong impact of the molecules of cooler air in a breeze than when it is surrounded by ‘a still atmosphere. The error thus introduced into the observations by a light breeze, however, does not seem to be serious, for I have not found it to exceed 0°°7 C.; but in a high wind it would probably be more considerable. The results of the foregoing experiments disclose the precautions necessary to be observed to render such determinations of relative solar intensity fairly comparable and trustworthy. They are the following :— 1. The vacuous globe should always and everywhere be placed upon the same kind of horizontal reflecting surface. 2. The temperature of the air upon this reflecting surface should be taken as the shade temperature, and its observation should be syn- chronous with that of the sun-thermometer. 3. The horizon all round the instrument should be as free as possi- ble, and there should be, especially, no sunlit walls in such a position as to reflect heat upon the thermometer. 4. As far as compatible with these conditions, the solar thermo- meter should be sheltered from the wind. The white surface on which the thermometers are laid need not be of large area. A square foot practically affords to the blackened bulb in vacuo a reflective plane of infinite extent, for I have ascer- VOL. XXXIII. 2B 338 Dr. E. Frankland. On Measuring the [Feb. 2, tained that the indicated solar intensity is not augmented when the area of white surface is increased fourfold. There is not much use in having self-registering shade and sun thermometers, because the highest temperature of the blackened bulb: does not necessarily occur at the time of maximum shade tempera- ture; and, consequently, the maximum solar intensity during any period cannot be found by merely deducting the maximum shade from the maximum sun temperature. Correct observations of maxi- mum solar intensity are, therefore, very laborious with these instru- ments; and are, I believe, never made in the routine work of a meteorological station. As they afford, however, very interesting data, I have endeavoured to simplify them by contriving an instru- ment which allows them to be recorded for each day with one reading only. | A Differential Self-Registering Temperature, for measuring relative solar intensity. This instrument, as seen from the accompanying figure, has consider- able similarity to a Leslie’s differential air thermometer; but in the new instrument the differential changes in the elasticity of the air of the two bulbs are measured by their action in elevating a column of mercury. 1882. ] relative Thermal Intensity of the Sun. 339 A, B are the two bulbs, 20 millims. in diameter, one of which, A, is blackened in the usual way, and then sealed into the larger clear glass globe, C, which has a small neck at ¢ for attachment to a Sprengel pump. As soon as a good vacuum has been obtained, the neck is sealed off before the blowpipe, as shown in the figure. The other bulb, B, is shaded by a small zine arch, f, 3 inches long, painted on both sides with “flatted ” zinc-white. These bulbs are connected by a tube bent twice at right angles and furnished at d with a branch and stopcock. The tube from the bulbs to e ¢ is of the diameter of that of a self- registering spirit thermometer, but the remaining part of it is much wider, in order to diminish the friction of the column of mercury moving init. The upright tube attached to B is provided witha scale, and the usual steel index is enclosed in the capillary part of it. The length of the scale is quite independent of the capacity of the bulbs, provided the volume of that part of the capillary tube in which the mercury oscillates is nearly a vanishing quantity in relation to the volume of the bulbs. It is well to have the two bulbs of nearly the same size, but a difference of capacity does not interfere with the accuracy of the instrument. The difference of the level of the mercury in the two limbs will be exactly proportional (neglecting the volume of the capillary tube) to the difference of temperature in the two bulbs, and the degrees of the scale, g, will therefore be equal throughout. The length of these degrees, however, though constant for any one instrument, will vary with the temperature and pressure at which the instrument has been filled, being greater the lower the temperature and the higher the pressure. At 0° C. and 760 millims. mercurial pressure, the difference of mercury level corresponding to 1° C. difference of temperature would be 2°784 millims., and the full length of these degrees may be practically obtained by making the wide portion of the tube longer in the limb A e than in Be, so that a minute depression of the mercury in A e will cause a great rise of the column in Be. The relative capacities of the capillary and wide tubes can be readily determined, and the necessary correction made in the readings for the depression of the mercury in Ae. The instrument may, however, be so constructed as to make the mercury rise and fall equally in both capillary tubes; in which case the rise in one limb would be accompanied by a corresponding fall in the other, and consequently the indicated degrees on the limb Be would be only half as long, 1°39 millims. corresponding to 1° C.—a graduation which is sufficiently open for all practical purposes. As a greater difference than 60° C. between the shade and sun thermometers has never been yet observed, a scale 163 millims. long in the one case, or half that length in the other, is sufficient, except perhaps for obser- vations at very great altitudes. As shown in the figure, the bulbs are supported upon a firm table, 2B 2 340 On Measuring the Thermal Intensity of the Sun. [Feb. 2, one foot square and of any convenient height. A slot is cut in the table of suitable size to permit of the passage of the (J-tube and stopcock, the aperture being subsequently closed bya slip of wood level with the top of the table. This table is painted on both sides with “ flatted ”’ zine-white, and its legs are firmly fixed in the ground, so that it cannot be disturbed by the wind. The branch tube, d, should also be anchored to the ground by elastic bands, so as to prevent any move- ment of the instrument from the same cause. It is, moreover, desir- able to surround the table with wire netting. By means of a funnel and flexible tube, mercury is now introduced cautiously into the (Jj-tube through the stopcock, d, until it reaches the zero of the scale, care being taken that both bulbs are at the same temperature (which should be noted) during the operation. The pressure upon the air in the bulbs must then be determined, and employed, together with the temperature, in calculating the length of each degree upon the scale. Once charged, the instrument must thenceforward be kept in its normal position, or nearly so, otherwise the mercury will get into the bulbs, whence it can only be dislodged with difficulty. In transporting the instrument from place to place it is therefore advisable to withdraw the mercury. The following comparative determinations of solar intensity were made with this instrument, and with the ordinary blackened bulb in vacuo read on white paper synchronously with a shade thermometer. | Solar intensity. Blackened bulb Shade in vacuo. temperature. Result of Self-registration | duplex of differential observation. instrument. s . 48-310. 29°0 C. 19°3 ©. 20-0 C. 49-0 29 -2 19°8 20°5 49 °7 29 °2 20°5 20°5 46 °3 28 °7 17-6 16°9 45 ‘9 28 °4 7s 17-5 48 °4, 29°3 TOG 20 *4 50-0 29°7 20°38 20°3 47-0 29 °5 17/35) el, 43 +2 27-4 15 °8 16:1 1882. |] W. Spottiswoode. On Russell's Integrals. d41 February 9, 1882. THE PRESIDENT in the Chair. The Right Hon. Henry;Fawcett was admitted into the Society. The Presents received were laid on the table and thanks ordered for them. The following Papers were read :— [. “ Note on Mr. Russell’s paper, ‘On certain Definite Integrals. No. 102” By WiLuiam Spottiswoopg, M.A., D.C.L, LL.D., Pres. R.S. Received January 30, 1882. If in Mr. Russell’s paper* we take the standard forms— (Qn 052 es Lt (a Bs yp) (Nae? 2 nee v,, 1), we shall have for eliminating «, B, y, \, m, v, the five equations :— a=an b=aNm, 3c=2ap2+arv+ Pr, d= apy + Bu, e= av?+2Bv+y, the last of which alone contains y, and may therefore be omitted for the present purpose. Combining the remaining equations, it will be found that 36u—AN= ap, from which both 8 and v have simultaneously disappeared. Hence we have the three equations— GN); Nu (dcw—AN)) = fa, for the elimination proposed. These readily give— a’d—3abe+2b°=0. Again, for the sextic— (a,b, . « .)(@, 1)8=(a, B, y 8) (da®+ Que+v, 1)5, * “ Proc. Roy. Soc.,”’ vol. 33, p. 258. 342 W. Spottiswoode. On Russells Integrals. — [Feb. 9, we have, omitting as before the last equation, viz., that connecting g and 6— G= Van, b= adm, Sex adv +4adp2+ Br, od =8ahpv + 2ap > + 3A, Se= adv?+4davp2+2Br.v+4hu2+yar, | f= apr? + 2Bpy + yp. Combining these, it will be found not only that, as in the case of the quartic, ! Scu— AN=2adp? ; but also that An? . 5d—3unr . 5e+3df=Bap, from which both 8 and v have simultaneously disappeared. Hence we have for the elimination of a, X, «, the four equations :— a==an3, b=ah*u, SCu— A= adm, 20dp? — l5erkw+ 38/2 =8ap, from which it is easy to derive the two final conditions— a’d—d8abe + 2b°=0, and 20a*b?d—15da%be + 8a4f—8b°=0. It would perhaps be difficult to obtain the results for the general ease by the present method; but if the question be regarded from a different point of view, we can see not only how many conditions will exist in general, but also what will be their form; and, moreover, we can actually obtain them in any particular case. The problem is in fact identical with that of finding the conditions under which an equation of the degree 2n can be solved by means of an equation of the degree n. To answer this, we have merely to sub- stitute in the equation (a, b, . . .)(a, 1)2=0 2+w for #, and equate to zero the coefficients of the odd powers of @. This will give n equations, from which we can of course eliminate w in n—1 ways; and the results of the eliminations will consequently be the conditions sought, n—1lin number. Applying this to the case of the sextic, we have CRUEL Gyo 0s 1882. | Dr. W. Fight. On Meteorites. 343 and if we equate to zero the coefficients of x, x, w, we shall have the equations— (a, 6) (w, 1)=0, (ayo. cd) Go, te —=0; (Gy Op 05 Ch Cou? Glo 120), Whence, eliminating w between the first and second of these, we obtain— (a, b, C, d) (0, —a)yr= ? (a, D, €, d, e, f )(, —a)°>=0; or, developing the expressions, OI BONO ALA) Ee ee es (IU) as before, and a*f—5a°be+ 10a2b?d—10ab?c+46°=0 . . . . (2). In order to bring this to the same form as the condition found by the other method, we have only to write, for (2), the following, viz., 3(2) —1002(1)=0, which gives 3a*f—15a%be+ 20a2b?d—8b°=0, as before. It is unnecessary to pursue the subject further, as the method is pertectly general and obvious in its application. Il. “Report of an Examination of the Meteorites of Cranbourne, Australia; of Rowton, Shropshire; and of Middlesbrough, in Yorkshire.” By WATER FuicHT, D.Sc., F.G.8., of the Department of Mineralogy, British Museum, South Ken- sington. Communicated by H. DrBus, Ph.D., F.R.S. Re- ceived January 19, 1882. (Abstract. ) I.—The Siderites of Cranbourne, near Melbourne, Australia. The large masses of meteoric iron found at Cranbourne, near Mel- bourne, Australia, were known as far back as 1854. The larger block was bought by Mr. A. Bruce, now of Chislehurst, for one sovereign, who determined to present it to the British Museum. The smaller mass, weighing a few hundredweight, became the property of Mr. Abel, and was sent to the International Exhibition of 1862. When 344 Dr. W. Flight. On Meteorites. [Feb. 9,. the block belonging to Mr. Bruce came to be uncovered and moved it was found to weigh 3} tons. Some difficulties arose respecting its shipment to England, and eventually Mr. Abel’s block was purchased for 300/. by the Trustees of the British Museum, and presented to the colony, and the larger mass was sent to this country. They lay 3°6 miles apart; and the major axis of the Bruce meteorite, sume 5 English feet, lay exactly in the magnetic meridian of the place. The Bruce meteorite consists entirely of metallic minerals, and eontains no rocky matter whatever. The iron contains no combined carbon, but from 7 to 9 per cent. of nickel, some cobalt, a little silicium, and copper; and, distributed through its mass, rather less than 1 per cent. of bright, apparently square prisms of a phosphide. Lying on the plates of meteoric iron, which make up the mass, were found thin metallic plates of the thickness of writing paper, of a flexible mineral, which had the composition Fe.Ni,. It is this mineral which forms the figures on etched surfaces, and not schrei- berite as generally stated. I propose to call this compound Edmond- sonite, in memory of the late George Edmondson, the Head Master of Queenwood College, a great lover of science; a man with whom | had the honour to be long and intimately connected. Nodules of troilite, varying from half an inch to two inches in length, are frequently met with. The composition of the sulphide proved it to be the iron monosulphide beyond question. Occasionally nodules of graphite were noticed, enclosing troilite in curious pointed forms, so that a section resembles the outline ofa holly leaf. The prisms already referred to appear to be identical with the mineral to which Gustav Rose gave the name of rhabdite, and to have the composition indicated by the formula (Ie,Ni,)P. The resemblance between them and the phosphide described by Sidot, and more recently by Mallard, is gone into. an) goo “quowttedxa T G T eat it SEF 8 © ie oR aa ino Sine eves ais rae ST TT CO UL OAN OW p T H g T P pees: 6 T 66 Z ‘9onp T | wee T | -oad 03 4mmonjrp Surjvoms ‘urstyeuneyA Oanow-qng | iT Tal? = z I “AON iE SEE OO ONDE AD OOD ONTO OG y SY) EPALU Kova tq}! a) a Lpileaes € T ce Z “AY ATVoy, ie | ee T | ostmazoqjo ‘sojyeyzI,T YIIM popvoy ourmn ‘“Yaurwgeg | O Da Te Z ‘poonpoad ATIsve qT |‘sny | T | suyvoms ‘vorsdoap ‘ormoayo ‘esvostp s4ysiug | LQ g |° vp oures oy} uo opeut “G pus g syuoutodxy “¢ jo ea eS (yy | Z, |° ep oures oy} uo opvut ‘y pus g syuoutsodxg cc : (79 ce i iy V va ean ac T| 4me | py [orcicctecr etree teense ees goolans AagqeeR | -¥ Y o| 2 |g2 : Bio| ae | ee e e © o> & Se) eee ‘SyAVMIOY 8 Z rr | Bo S Fh | “a eaeig Q F $ 1882. | Chemical Theory of Gunpowder. 361 February 23, 1882. THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. THE BAKERIAN LECTURE on the “Chemical Theory of Gun- powder,” was delivered by Professor H. DeBus, Ph.D., F.RS. Received February 8, 1882. The following is an Abstract :— 1. Dr. Jebb* mentions a manuscript as existing at Oxford, entitled ‘Liber ignium ad comburendos hostes,” by Marcus Grecus, probably written in the eighth century, wherein the preparation of gunpowder is accurately described, and Bellani reports that the English used cannon at the Battle of Crecy. Gunpowder, therefore, has been known more than a thousand years, and its use for the purposes of war more than five hundred, nevertheless, no chemical theory of the combustion of gunpowder has hitherto been proposed which will enable us to calculate the quantity of each of the chief products of combustion from the known composition of a given weight of powder, or the amount of heat generated during its metamorphosis. A theory which can solve these problems I have the honour to submit in the present paper to the Royal Society. 2. The constituents of gunpowder—saltpetre, charcoal, and sulphur —are transformed during combustion into the following products :— Potassic carbonate, potassic sulphate, potassic disulphide, potassic sulphocyanate, carbonic acid, carbonic oxide, nitrogen, sulphuretted hydrogen, marsh-gas, ammonia, hydrogen, and water. The hydrogen compounds—sulphuretted hydrogen, ammonia, and marsh-gas, the free hydrogen and potassic sulphocyanate—do not, as a rule, amount together to more than about two per cent. of the weight of the powder from which they have been produced; and as their formation is not the direct result of the reactions which cause the explosion of the powder, they are regarded as secondary products and not considered in a discussion of the chemical metamorphosis of gunpowder. Besides the potassium salts mentioned, potassic hyposulphite has been found as one of the constituents of the solid residue left by powder after its explosion. According to experiments by the author, which have been confirmed by Noble and Abel, this salt is formed in considerable quantities from potassic sulphide during the analysis of * Pogeendorff, “ Geschichte der Physik,” 87. 362 Dr. H. Debus. | [Feb. 23, the residues according to Bunsen and Schischkoff’s method ; and as it is decomposed at 225° C., it cannot be considered as one of the chief products of the combustion of gunpowder. 3. With regard to the products, potassic carbonate, potassic sul- phate, potassic disulphide, carbonic acid, carbonic oxide, and nitrogen, the following problems have to be solved :-— (a.) To determine the reactions which cause the formation of these substances and the order in which they succeed each other, and to represent the complete combustion of gunpowder by one chemical equation. (b.) To calculate from the known composition of a given weight of powder the volume of gas and the amount of heat generated during its combustion, and to ascertain the relative energies of powders of different composition. The solution of each of these problems is described in the paper. 4. Noble and Abel* describe the quantitative relations of the products of combustion of a given weight of powder of known com- position in the following words :— ‘“‘(a.) The proportions in which the several constituents of solid powder residue are formed are quite as much affected ‘by slight acci- dental variations in the conditions which attend the explosion of one and the same powder in different experiments, as by decided differences in the composition as well as in the size of grain of different powders. ‘“*(b.) The variations in the composition of the products of explosion furnished in close chambers by one and the same powder under diffe- rent conditions, as regards pressure, and by two powders of similar composition under the same conditions, as regards pressure, are so considerable, that no value whatever can be attached to any attempt to give a general chemical expression to the metamorphosis of gun- powder of normal composition. ““(c.) Any attempt to express, even in a comparatively complicated chemical equation, the nature of the metamorphosis which a gun- powder of average composition may be considered to undergo, when exploded in a confined space, would therefore only be calculated to convey an erroneous impression as to the simplicity or the definite nature of the chemical results and their uniformity under different conditions, while it would, in reality, possess no important bearing upon an elucidation of the theory of explosion of gunpowder.+ “(d.) Very small-grain powder, such as F.G. and R.F.G., furnish decidedly smaller proportions of gaseous products than a large-grain powder, R.L.G.: while the latter again furnishes somewhat smaller proportions than a still larger powder, P, though the difference between the gaseous products of these two powders is comparatively inconsiderable.”’ * “Phil, Drans., @clxy (875), pr tor: UEP ENDL, We SO 1882.] Chemical Theory of Gunpowder. 363 Noble and Abel exploded successively portions of powder of the same description in their apparatus, and found considerable fluctua- tions in the relative quantities of the products of explosion in different experiments. These fluctuations they do not explain, but state that “ slight accidental variations in the conditions which attend the explosion,” have as much influence on the relative quantities of the constituents of the solid powder residue as decided differences in the composition of the different powders. And as the exact nature of these “slight accidental variations in the conditions which attend the explosion”’ is not known, they conclude that the metamorphosis cannot be repre- sented by a chemical equation. The author of this abstract has described in the paper the causes of the variations in the relative quantities of the products of explosion, and has explained the experimental results of Messrs. Noble and Abel. And further, he has been able, with this knowledge, to repre- sent the chemical metamorphosis of the Hnglish Service powders by an equation. 5. Noble and Abel assume that the samples of fine-grain and pebble powders used in their numerous experiments were, respectively, of the same composition, and that the samples of R.L.G. powder employed in their earlier experiments, had the composition given under “I,” and those used in the later experiments that given under ‘‘ II” in the table below. ‘The composition of the same description of powder is, however, not constant. I requested the late Mr. Wills to analyse pebble and R.L.G. powders from Waltham Abbey, and the results obtained by him, together with those of Noble and Abel, are given in the following table :— R.L.G. Pebble powder. Noble and Abel. Noble Wills. and Wills. I | IL Abel. Saltipetres. 66. 6.j.esec ee eciee oe 14°95) | 74°48) 757105 | TA67) |) 74°26 SMUD MUN coos iss ss A sicki reas | LO ZT 10 ‘09 8 96 10:07 9°51 Charcoal— Cupvon AUPE ES LU ORE 10 ‘86 12°40 | 12°09 12°12 11°58 IsLycii@egiie bo omoe bod ceo oo | ae 0°40 0°54 0°42 0°51 OSA CAST ae ORE CR each Peete Ea 1:99 1 40 2°12 1°45 2°55 22 \S1i optic OOO Geae RIOR ieeeci-al lam Oar 0°21 0°20 0°23 0°33 PRPC Ee Teas jets (atei clcle Cola alSlapiats fare oil tordis LL 1°05 0°85 0°95 0°76 The samples analysed by Noble and Abel were taken out of the 364 Dr. Hi Debus: [Feb. 23, same barrel, the one from the upper, the other from the lower parts. These two samples showed a difference of no less than 1°54 per cent. of the weight of the powder in the amount of carbon they contain, or the weight of carbon is by one-seventh greater in the second than in the first sample. Mr. Wills found 1:31 per cent. of sulphur less than Noble and Abel in the same description of powder. Such differences in the composition of samples of powder of the same nature, together with the usual errors attaching to complicated and dificult analytical operations, are almost sufficient to explain the variations in the proportions of the products of the combustion of gunpowder, as found by Messrs. Noble and Abel, without requiring a theory like the one proposed by M. Berthelot for that purpose. 6. Noble and Abel analysed the products of explosion by means of Bunsen aud Schischkoff’s method. The author has proved that by the treatment of the solid powder residue according to this method a portion of the potassic sulphide is converted into potassic hypo- sulphite, and under certain conditions into potassic sulphate. The quantities of the two salts so produced vary in different experi- ments. Hence, the fluctuations observed by Noble and Abel in the relative quantities of potassic sulphide, potassic sulphate, and potassic hyposulphite are partly, if not entirely, due to the method of analysis. Potassic hyposulphite is decomposed at temperatures above 225° ; from this fact, as well as from a comparison of the oxygen in the original powder with that of the products of explosion, it follows that the potassic hyposuiphite found in powder residues must be regarded as the product of the analytical method. 7. It is well known that the higher sulphides of potassium attack metals with great energy at a white heat. Noble and Abel exploded their powders in a hermetically closed steel cylinder at high pressures, and the products remained after explosion from one to two minutes in a fluid condition at a white heat in contact with the iron of the apparatus. These products contain potassic disulphide. The descrip- tion given by Noble and Abel of their solid powder residues indicates that they contain ferrous sulphide. The absorption of a portion of the sulphur by the iron will increase the amount of potassic carbonate and diminish the quantities of potassic sulphate and disulphide. The quantity of sulphur so uniting with iron depends on pressure, time of cooling, and other conditions, and will vary in different experiments. We have then in the formation of ferrous sulphide another cause of the fluctuation in the quantities of the products of explosion observed by Messrs. Noble and Abel. 8. It follows from the statements given under Nos. 5, 6, and 7, that there is no reason to assume that the chemical metamorphosis of gun- powder cannot be represented by an equation. 9. Noble and Abel calculate the total weight of the solid residue, 1882.] Chemical Theory of Gunpowder. 369 which a given weight of powder can produce by its explosion, from the composition of a portion of the residue and the composition of the powder. They assume that the portions of powder of the same description used in different experiments, were of the same compo- sition. This is, according to the statements under No. 5, not the case. The calculated quantities of gas and solid residue which a given weight of powder can produce, will, in consequence, be affected by certain errors. These errors compensate each other if the mean of ‘many experiments is taken. 10. Portions of powder taken from different parts of the same barrel show, according to Noble and Abel’s analyses, greater diffe- rences in their composition than samples of different descriptions manufactured at Waltham Abbey, pebble, rifle fine-grain, rifle large- grain, and fine-grain powder; hence, we are justified in taking the mean of the analyses of these powders, and expressing thereby the composition of the English Service powder. The mean of the analyses of Noble and Abel, and Wills, can be represented by the symbols— I6KNO,+21:18C + 6°638, if hydrogen, oxygen, and ash of the charcoal, and the hygroscopic moisture of the powder are neglected. 11. From evidence described in the paper it follows, with a high degree of probability, that during the combustion of gunpowder potassic disulphide, and not monosulphide, as is usually assumed, is formed. 12. If the errors arising from the analytical method are corrected as explained in the paper, if allowance is made for the sulphur which has united with the iron of the apparatus, and, finally, if, for the reasons adduced under No. 9, the mean is taken of the thirty-one analyses published by Noble and Abel, then the explosion of the powders of Waltham Abbey, as conducted by Noble and Abel in a confined space, can be represented very nearly, if not quite accurately, by the follow- ing equation :— 16KNO,+ 210 +5S=5K,CO,+ K,SO ee ace ee ante 1°63 atoms of the sulphur contained in the powder have united partly with hydrogen and formed sulphuretted hydrogen, partly with iron and produced ferrous sulphide. The entire amount of the oxygen contained in the charcoal is eliminated with hydrogen as water, the rest of the hydrogen either remains free or produces methane with carbon and ammonia with nitrogen. The composition of the powder, calculated from the mean composition of the products of explosion of thirty-one experiments, can be represented by the symbols 16KNO,+ 21-35C +6628, 366 Dr. H. Debus. [Feb. 23, which are almost identical with 16KNO,+ 21:18C + 6°638, representing the mean composition of the powders found by direct analysis. 13. An increase of pressure during combustion appears to diminish the amount of carbonic oxide, and, in consequence, according to equation 8, to increase the quantities of potassic carbonate, potassic disulphide, and carbonic acid. These fluctuations in the quantities of the products of combustion are, however, very small, and may be neglected without serious error. 14, Craig had asserted that the nature of the products of explosion of gunpowder depended on the pressure developed during combustion. Karolyi, in order to test this assertion, made experiments with Austrian Service powder, and arrived at the conclusion that pressure had no influence on the quality or quantity of the products furnished by these powders. The experimental results of Karolyi, and the differences between these results and those obtained by Noble and Abel, have enabled the author to develop a chemical theory of gunpowder competent to explain the cbservations of Bunsen and Schischkoff, Linck, Karolyi, Noble, and Abel, and other investigators, and which is in harmony with the thermochemical relations of the reacting substances. According to this theory the combustion of gunpowder takes place in two stages, one succeeding the other. The reactions of the first stage cause the explosion of the powder. Gunpowders which differ con- siderably in their composition are transformed during the first stage according to the equation 10KNO,+8C +38=2K,C0,+3K,S0,+6C0,+5N, . . (3), but as it is probable that at the same time some carbonic oxide is pro- duced, the following would more correctly represent the reactions :— 16KNO, +13C-+58=3K,CO,+5K,80,+9C0,+CO+8N, . (4), The constituents of the powder, and those of the products of com- bustion are, according to equation 4, nearly in the same ratios as they are according to 3. During the first stage of the combustion potassic disulphide is not formed. The oxygen of the potassic carbonate, potassic sulphate, and the carbonic acid, as represented by equation 3, stand to each other in the most simple possible ratios, if these substances are to be produced by the combustion of a mixture of saltpetre, carbon, and sulphur. In other words, equation 3 represents the most simple distribution of the oxygen of the decomposed saltpetre amongst the products of combus- 1882.] Chemical Theory of Gunpowder. 367 tion produced during the first stage. And because these products are, according to equation 4, nearly in the same relative proportions as they are according to 3, it follows that the distribution of the oxygen of the saltpetre between potassic sulphate, potassic carbonate, and carbonic acid, as required by equation 4, corresponds nearly to the most simple ratios which can exist under the conditions of the experi- ments. The oxygen of the potassic carbonate stands to the oxygen of the potassic sulphate and of the carbonic acid, according to equa- tion 3, as ieee Oe If a mixture of saltpetre, carbon, and sulphur shall produce, by its combustion, the greatest possible amount of heat, and if at the same time the products—potassic sulphate, potassic carbonate, and carbonie acid—shall be formed in such proportions that the heat of formation of one shall stand to the heat produced by each of the other two in the most simple ratio possible, then the combustion must take place according to equation 4. The heat developed by the formation of potassic carbonate stands to that furnished by potassic sulphate and carbonic acid respec- tively as | Ps 2°05; and 7 1: 1:04. if the powder is transformed according to equation 4. The relations between the quantities of oxygen in the chief products of combustion and those of the heat produced by their formation are, from a theoretical point of view, of the greatest interest. 15. Gunpowder, as a rule, contains more carbon and sulphur than is required by equations 3 and 4. The carbon left free at the end of the first stage of the combustion now acts on the potassic sulphate, formed during this stage, according to the equation 4K,S0,+ 7C=2K,C0,+2K,8,+5C0,. .°. . (©), and the free sulphur upon potassic carbonate according to | AVS COR (a= Kk SO),4- 3 KGS, ACO). re. 2 aaa). and some of the free carbon reduces carbonic acid to oxide. These reactions constitute the second stage of the combustion of geunpowder ; they are eudothermic, heat is not evolved but is rendered latent ; they are not of an explosive nature, and, in practice, are prob- ably seldom complete. During the second stage of the combustion the temperature of the products of explosion is diminished and the volume of the gas is increased. 368 Dr. H. Debus. [Feb. 23, 16. The quantitative relations between the constituents of gun- powder and the chief products of combustion at the end of the second stage can be expressed by one equation. If x, y, and z be positive numbers and a represents how many molecules of carbonic oxide are formed by the complete combustion of a weight of powder containing z molecules of saltpetre, y atoms of carbon, and z atoms of sulphur, we have tKNO,+yC+2S= 3,[4¢4+ 8y—16z2—4a](K,CO3) +,[207—16y + 42+ 8a](K,SO,) +3.[ —10v+ 8y + 12z—4a](K,8,) as| —4u + 20y + 162—24a](CO,) +aCO +40Ny once doce aloe sp as the general equation of the complete combustion of gunpowder. By means of this equation the chief products of combustion— potassic carbonate, potassic sulphate, potassic disulphide, and car- bonic acid—can be calculated from that portion of a given weight of powder which transforms itself into these products. The correctness of the equation is proved by the agreement of the calculated numbers with those observed by Bunsen and Schischkoff, Linck, and Karolyi in their experiments on the explosion of gun- powder, and also with the corrected mean numbers derived from Noble and Abel’s investigation. 17. The total volume of gas developed by the combustion of a given weight of powder, if calculated according to equation (8), is not affected to more than from one to two per cent. if we put a=0, and in doing so we gain a considerable simplification of the equation. If V represents the volume of gas evolved by the combustion of a quantity of powder containing 16 molecules of saltpetre, y atoms of carbon, and z atoms of sulphur, and W the units of heat developed by the same weight of powder, we have, on the assumption that a=. - _ 160+20y+16z V 7 oy hee (9); W =1000[1827°154—16°925y—8:788z] . . . (10). The volume of gas becomes greater, and the amount of heat diminishes, when y and z are increased, and vice versd. Quantities of saltpetre, carbon, and sulphur represented by the symbols 16KNO;+8C+858 produce the greatest amount of heat and smallest amount of gas, and such as correspond to— 16KNO, +240+16S, 1882. | Chemical Theory of Gunpowder. 369 the largest volume of gas and the smallest quantity of heat, if the mixtures are considered which can transform themselves during com- bustion according to equation (8), in which a is put =0. (8.) The product of (9) and (10) divided by 2 x 1009, Vx Ww ge tee —12:09y? + 1208°39y —15-95yz+ 993°8672— 50222? = 19, git 2 eae ee aaa ae aman Od Ror eae Ie will assume different values for powders of different composition. The energy of a mixture of saltpetre, carbon, and sulphur will be, ceteris paribus, proportional to the volume of gas, and also to the amount of heat produced during its combustion. Hence, the product of the two, EH, may be used, according to the proposal of M. Berthelot, as a measure of the relative energies of powders of different com- position. (9.) If in equation (8) x is put =16, and a=0, we obtain: 16(KNO;)+yC+zS= ,[64+8y—16z](K,CO;) _ + 3,[320—16y +4z](K,S0,) +,[ 160+ 8y +12z](K,8,) +,[—64+ 207 +16z](CO,) SS iNias J Meese Maen pr RY aserTO @ISY, and from this, if the coefficients of the potassic carbonate, potassic sulphate, and potassic disulphide are put =0, the equations: Gey Ver O Oe aay. sooemtGy -e4c=0 (yo. et a CL SENGO+ Sy l22= Oe ce Ty 4 ua leciy URLONE These equations represent in a plane three sides of a triangle. The co-ordinates of points within this triangle represent quantities of carbon and sulphur, which can, with 16 molecules of saltpetre trans- form themselves according to equation (13), whereas the co-ordinates of points outside this triangle indicate mixtures which cannot do so, such mixtures containing either too much or too little of carbon or sulphur. The co-ordinates of poimts on the sides of the triangle represent mixtures which will burn with the production of two, and those of the points of intersection of two sides with formation of only one potassium salt. The two sides represented by equations (14) and (16) intersect in point y=8, and z=8. These values introduced into (13) give: 16KNO,+ +8C0+8S=8K,80,+ 8CO,+8N,. MODs. XXXII. 2D 370 Chemical Theory of Gunpowder. [Feb. 23, In the same manner we obtain for the point of intersection corre- sponding to equations (15) and (16): 16KNO,+ 20C=8K,C0,+12C0,+8N,, and finally, the sides whose equations are (14) and (15), intersect in point y=24 and z=16, hence 16KNO,+24C+16S=8K,8, + 24C0, + 8Np. The geometrical construction of the co-efficients of equation (18) possesses the great advantage of indicating by the co-ordinates of the points of a triangle the composition of the infinite number of mixtures of saltpetre, carbon, and sulphur which can transform themselves during combustion according to equation (15), and enables us to deduce geometrically, as is shown in the paper, the qualitative nature and the quantitative relations of the products of combustion, as well as the volume of gas and the amount of heat developed by each mixture. (20.) It is proved in the paper that the composition of a powder which can transform itself during combustion according to equation (13), and for which E in equation (11) shall be a maximum, is in- dicated by the co-ordinates of the point of intersection of the sides of the triangle represented by the equations (14) and (15). If, therefore, such quantities of powders of different composition are compared, which contain 16 molecules of saltpetre, the one com- posed of 16KNO,+240+16S will possess the greatest energy. (21.) If E is calculated for equal weights of two powders of different composition, the difference of the values of EH is found to be very small, if the powders contain from 21 to 24 atoms of carbon, and from 8 to 16 atoms of sulphur for every 16 molecules of saltpetre. Equal weights of the two mixtures 16K NO, +220 +88, and 16KNO,+ 24C +168, give for EH [equation (11)] the values 16°84 and 16°95 respectively. If, therefore, a mixture of saltpetre, carbon, and sulphur is required, which shall possess the greatest or nearly the greatest amount of energy, and at the same time contain the smallest amount of carbon and sulphur compatible with this condition, theory would point to the mixture 16KNO;+ 22C +88. The gunpowders of most nations fluctuate about 16KNO,+ 21:20 +6°88, which numbers are very near those required by theory. 1882. ] Presents. 371 Presents, February 2, 1882. Transactions. Adelaide :—South Australian Institute. Annual Report, 1880-81, and Appendix F. 8vo. Adelaide. (2 copies.) The Institute. Brighton :—Natural History Society. Annual Report, 1880-81. 8vo. Brighton 1881. The Society. Brunswick:— Verein fir Naturwissenschaft. Jahresbericht. 1880-81. 8vo. Altenburg 1881. The Union. | Brussels :—Académie Royale de Médecine. Mémoires Couronnés. Tome VI. Fasc. 3. 8vo. Bruxelles 1881. The Academy. Buckhurst Hill:—EHpping Forest and County of Essex Naturalists’ Field Club. 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Braidwood, Peter Murray, M.D. Browne, James Crichton, M.D., ADS HR aSabe Buchanan, George, M.D., F.R.C.P. Clarke, Charles Baron, M.A., ID DeSi4 Gosh Creak, Ettrick William, Staff- Commander R.N. Cunningham, Allan Champneys, Major R E. Curtis, Arthur Hill, A.M., LL.D., D.Se. Dallas, William Sweetland, F.L.S. Darwin, Francis, M.A., M.B., E.L.S. Day, Francis. Dittmar, Professor William, F.C.S., F.R.S.H. Dobson, George Edward, M.A., M.B., F.L.S. Flight, Walter, D.Sc., F.G.S. Foster, Professor Balthazar Walter, F.R.C.P. Joseph Gaskell, Walter Holbrook, M.A,, | M.D. Glazebrook, Richard Tetley, M.A. Godman, Frederic Du Cane, aS beGas: Goodeve, Professor Thomas Minchin, M.A. Groves, Charles Edward, F.C.S. Grubb, Howard, F.R.A.S. Hartley, Professor Walter Noel, F.R.S.E. Hutchinson, Jonathan, F.R.C.S. Ley, Rev. W. Clement, M.A. Liversidge, Professor Archibald, E.G:S, F.C:S5 lines: Malet, Professor John, M.A. Meldola, Raphael, F.R.A.S. Miller, Francis Bowyer, F.C.S. Niven, William Davidson, M.A. Ord, William Miller, M.D., F.L.S., ident Gale Palgrave, Robert Henry Inglis, F.S.8. Pattison, Samuel Rowles, F.G.S. Pritchard, Urban, M.D., F.R.C.S. Ransome, Arthur, M.A., M.D. Ranyard, Arthur Cowper, F.R.A.S. Rawlinson, Robert, C.B., M.1.C.H. Reinold, William Arnold, M.A. Tidy, Charles Meymott, M.B., HCAS: Topley, William, F.G.S. Trimen, Roland, F.L.S., F.Z.S. 1882.] On the Epidemic known as the “ Salmon Disease.” 381 Venn, John, M.A. Williams, Charles Theodore, M.A., Walker, John James, M.A. VED nn C.P: Warrington, Robert, F.C.S. Wright, Professor Hdward Per- Watson, Professor Morrison, M.D. ceval, M.A., M.D., F.L.S. Weldon, Walter, F.C.S, F.R.S.E. The following Papers were read :— I. «A Contribution to the Pathology of the Epidemic known as the ‘Salmon Disease.” By Professor T. H. HUXLEY, LL.D., F.R.S. Received February 21, 1882. For some years, an epidemic disease, followed by a very large number of deaths, has been observed to prevail among the salmon of certain Scottish and British rivers, from the Tay,* on the north, as far as the Conway on the south. The first obvious symptom of the malady is the appearance of one or more greyish patches upon the skin of parts of the body which are not covered with scales, such as the top and sides of the head, the adipose fin, and the soft skin at the bases of the other fins. Such a patch, when it first attracts attention, may be as big as a sixpence. It is nearly circular, with a well defined margin and a some- what raised softer centre, from which faint ridges radiate towards the circumference. It is important to observe that a single small patch of this kind may be seen on the skin of a fish which, in all other respects, is perfectly healthy, and when there is no indication that the skin has ever been bruised or abraded in the place occupied by the patch. The patch, once formed, rapidly increases in size and becomes confluent with any other patches which may have appeared in its neighbourhood. The marginal area, as it extends over the adjacent healthy skin, retains its characters; but the central part undergoes an important change. It takes on the consistency of wet paper, and can be lifted up in soft flakes, as if it were a slough, from the surface of the derma or true skin, which it covers. In fact, it is obvious that this papyraceous substance has taken the place of the epidermis, so that the sensitive and vascular true skin is deprived of its natural protection. As the patch spreads, the true skin beneath the central papyraceous slough ulcerates and an open bleeding sore is formed, which may extend down to the bone, while it passes outwards into burrowing sinuses. When the disease has reached this stage it obviously causes great irritation. The fish dash about and rub themselves against stones, and thus, in all probability, aggravate the evils under which they suffer. * Within the last few days I have received specimens of diseased fish from the North Esk. (March 8.) PA AN es 382 ‘Prof. T. H. Huxley. Pathology of the [ Mar. 2, | One vast open sore may cover the top of the head from the snout to the nape, and may extend over the gill covers. The edges of the fins become ragged; and, sometimes, the skin which invests them is so completely frayed away that the fin-rays stand out separately. Although the affection of the skin appears, usually, 1f not invari- ably, to commence in the scaleless parts of the body, it does not stop there, but gradually spreads over the whole of the back and sides of the fish, though I have not yet seen a specimen in which it covered the whole ventral surface. The disease extends into the mouth, especially affecting the delicate valvular membrane attached to the inner sides of the upper and the lower jaws. It is said to attack the gills, but there has been no sign of it on these organs in any fish which I have had the opportunity of examining. Fish which succumb to the disease become weak and sluggish, seeking the shallows near the banks of the river, where they finally die. The flesh of a salmon affected by this disease presents no difference in texture or colour from that of a healthy fish; and those who have made the experiment declare that the flavour is just as good in the former case as in the latter. So far as my observations have gone the viscera may be perfectly healthy in the most extensively diseased fish ; and there is no abnormal appearance in the blood. It is known that a disease similar to that described is occasionally prevalent among salmon in North America and in Siberia; and I do not see any ground for the supposition that it is a novelty in British rivers. But public attention was first directed to it in consequence of its ravages in the Solway district a few years ago; and, in 1879, a Commission was appointed by Sir Richard Cross, then Home Secretary, to inquire into the subject. The evidence taken by the Commissioners* leaves no room for doubt that the malady is to be assigned to the large and constantly in- creasing class of diseases which are caused by parasitic organisms. It is a contagious and infectious disease of the same order as ringworm in the human subject, muscardine among silkworms, or the potato disease among plants; and, like them, is the work of a minute fungus. In fact, the Saprolegnia which is the cause of the salmon disease is an organism in all respects very closely allied to the Peronospora, which is the cause of the potato disease. It is a very curious circumstance, however, that while the Perono- spore are always parasites—that is to say, depend altogether upon * “ Report on the Disease which has recently prevailed among the Salmon in the Tweed, Eden, and other Rivers in England and Scotland.’ By Messrs. Buckland, Walpole, and Young, 1880. See also the three valuable communications to the “ Proceedings of the Royal Society of Edinburgh,”’ made by the late Mr. A. B. Stirling in 1878-79. 1882. | Epidemic known as the “ Salmon Disease.” 383 living plants for their support—the Saprolegnice are essentially sapro- phytes ; that is to say, they ordinarily derive their nourishment from dead animal and vegetable matters, and are only occasionally parasites upon living organisms. In this respect they resemble the Bacteria, if the results of recent researches, which tend to show that pathogenic bacteria are mere modifications of saprogenic forms, are to be ac- cepted. As I have said, I do not think that the evidence laid before the Commission of 1879 can leave any doubt as to the causation of the salmon disease on the minds of those who are acquainted with the history of the analogous diseases in other animals and in plants. Nevertheless, this evidence, valuable as it is, suggests more questions than it answers, and in November, 1881, hearing that the disease had broken out in the Conway, I addressed myself to the attempt to answer some of these. It was already known that when the papyraceous slough-like sub- stance which coats the skin of a diseased salmon is subjected to microscopic examination, it is found to be a mycelium, or fungus-turf, composed of a felt-work of fine tubular filaments or hyphe, many of which are terminated by elongated oval enlargements, or zoosporangia. Within these the protoplasm breaks up into numerous spheroidal par- ticles, each less than 5,755 of aninch in diameter. These, the zoospores, are set free through an opening formed at the apex of the zoosporangium, and become actively or passively dispersed through the surrounding water. Herein lies the source of the contagiousness or infectiousness of the disease. For any one of these zoospores, reaching a part of the healthy skin of the same or of another salmon, germinates and soon gives rise to a mycelium similar to that from which it started. But I could find no satisfactory information as to the manner in which the fungus enters the skin, how far it penetrates, the exact nature of the mischief which it does, or what ultimately becomes of it; nor was the identity of the pathogenic Saprolegnia of the salmon with that of any known form of saprogenic Saprolegnia demonstrated. It appeared to me, however, to be useless to attempt to deal with the disease until some of these important elements of the question were determined. To this end, in the first place, I made a careful examination of the minute structure of both the healthy and diseased skin, properly hardened and cut into thin sections; and, in the second place, I tried some experiments on the transplantation of the Saproleguia of the living salmon to dead animal bodies. Perhaps it will conduce to intelligibility if I narrate the results of the latter observations first. The body of a recently killed common house-fly was gently rubbed two or three times over the surface of a patch of the diseased skin of a salmon and was then placed in a vessel of water, on the surface of which 384 Prof. T. H. Huxley. Pathology of the [Mar. 2, it floated, in consequence of the large quantity of air which a fly’s body contains. In the course of forty-eight hours, or thereabouts, innumer- able white cottony filaments made their appearance, set close side by side, and radiated from the body of the fly in all directions. As these filaments had approximately the same length, the fly’s body thus became inclosed in a thick white spheroidal shroud, having a diameter of as much as half an inch. As the filaments are specifically heavier than water, they gradually overcome the buoyancy of the air contained in the trachee of the fly, and the whole mass sinks to the bottom of the vessel. The filaments are very short when they are first discernible, and usually make their appearance where the integument of the fly is softest, as between the head and thorax, upon the proboscis, and between the rings of the abdomen. These filaments, in their size, their structure, and the manner in which they give rise to zoosporangia and zoospores are precisely similar to the hyphe of the salmon fungus; and the characters of the one, as of the other, prove that the fungus is a Saprolegnia and not an Achlya. Moreover, it is easy to obtain evidence that the body of the fly has become infected by spores swept off by its surface when it was rubbed over the diseased salmon skin. These spores have in fact germinated, and their hyphe have perfo- rated the cuticle of the fly, notwithstanding its comparative density, and have then ramified outwards and inwards, growing at the expense of the nourishment supplied by the tissues of the fly. This experiment, which has been repeated with all needful checks, proves that the pathogenic Saprolegnia of the living salmon may become an ordinary saprogenic Saprolegnia ; and, per contra, that the latter may give rise to the former; and they lead to the important practical conclusion that the cause of salmon disease may exist in all waters in which dead insects, infested with Saprolegnic, are met with; that is to say, probably in all the fresh waters of these islands, at one time or another. On the other hand, Saprolegnia has never been observed on decaying bodies in salt water, and there is every reason to believe that, as a saprophyte, it is confined to fresh waters.* Thus it becomes, to say the least, a highly probable conclusion that we must look for the origin of the disease to the Saprolegnic which infest dead organic bodies in our fresh waters. Neither pollution, drought, nor overstocking will produce the disease if the Saprolegnia is absent. The most these conditions can do is to favour the develop- ment or the diffusion of the materies mordt where the Saprolegnia already exists. Having infected dead flies with the salmon Saprolegnia, once from * So far as I know, there is only one case on record of the appearance of a fungus on a fish in salt water, and in this case it is not certain that the fungus was a Sa- prolegnia. 1882. | Epidemic known as the “ Salmon Disease.” 385 Conway and once from Tweed fish,* I was enabled to propagate it from these flies to other flies, and, in this manner, to set up a sort of garden of Saprolegniec. And having got thus far, I fancied it would be an easy task to determine the exact species of the Saprolegnia with which I was dealing, from the abundant data furnished by the works of Pringsheim, De Bary, and others, who have so fully studied these plants when cultivated on the same materials. For this purpose, it was necessary to obtain the oosporangia; and, in ordinary course, these should have made their appearance on my Saprolegnie in five or six days. Unfortunately, in the course of cultivations continued over two months, nothing of the kind has taken place. Zoosporangia have abounded in the ordinary form and also in that known as “ dictyo- sporangium,”’ but, in no instance, have any oosporangia appeared. After a few days of vigorous growth, the zoosporangia become scanty, and the fungus takes on a torulose form, segments of the hyphze becoming swollen and then detached as independent “ gemme,”’ which may germinate. Sometimes the gemme are spheroidal and terminal, and closely simulate oosporangia. Although, therefore, I have very little doubt that the Saprolegnia of the salmon is one of the forms of the “SS. ferax group” of Pringsheim and De Bary, I have, at present, no proof of the fact. Another very curious and unexpected peculiarity of the salmon Saprolegnia, both on the fish and when transmitted to flies, so far as my observations have hitherto gone, is that locomotive ciliated zoospores do not occur. 1 once saw one which exhibited a very slight motion for a few minutes after it left the zoosporangium; but although thousands must have passed under my notice, with the ex- ception to which I have referred, they have always been perfectly quiescent and not unfrequently in different stages of germination. Whether the season of the year, or the conditions under which my saprolegnised flies were placed, have anything to do with the non- appearance of oosporangia and of locomotive zoospores in them I cannot say. But it is certain that the Saprolegnia ferax which com- monly appears upon dead flies and other insects normally develops both oosporangia and locomotive zoospores in abundance. From such notices by other observers as I can gather, oosporangia appear to be of very rare occurrence in the Saproleguia of the salmon itself. Mr. Stirling mentions that he has met with them only four times. With respect to locomotive zoospores, I can find no positive evidence that they have been regularly, or even frequently, observed in the salmon Saprolegnia. But these points require careful investi- gation on freshly taken diseased fish. Whether the zoospores are actively locomotive or not, they are quite * And since this paper was read once more from the North Esk fish. (March 8, 1882.) 386 Prof. T. H. Huxley. Pathology of the . [Mar. 2, free when they emerge from the zoosporangia; and, from their extreme minuteness, they must be readily carried away and diffused through the surrounding water. Hence, a salmon entering a stream inhabited by the Saprolegiia will be exposed to the chance of coming into con- tact with Saprolegnia spores; and the probability of infection, other things being alike, will be im proportion to the quantity of the growing Saprolegma, and the vigour with which the process of spore- formation is carried on. At a very moderate estimate, a single fly may bear 1,000 fruiting hyphe; and if each sporangium contains twenty zoospores, and runs through the whole course of its develop- ment in twelve hours, the result will be the production of 40,000 zoospores in a day, which is more than enough to furnish one zoo- spore to the cubic inch of twenty cubic feet of water. Hven if we halve this rate of production, it is easy to see that the Saprolegnia on a single fiy might furnish spores enough to render such a small shallow stream as salmon often ascend for spawning purposes, dangerous for several days. But a large fully diseased salmon may have as much as two square feet of its skin thickly covered with Saprolegnia. If we allow only 1,000 fruiting hyphe for every Square inch, we shall have 288,000 for the whole surface, which, at the same rate as ‘before, gives over 10,000,000 spores for a day’s production, or enough to provide a spore to every cubic foot of amass of water 100 feet wide and 5 feet deep and four miles long. Forty such diseased salmen might furnish one spore to the gallon for all the water of the Thames (380,000,000. gallons per diem) which flows over Teddington Weir. But two thousand diseased salmon ~ have been taken out of a-single comparatively insignificant river in the course of a season. It will be understood that the above numerical estimate of the pro- ductivity of Saprolegnia, has been adopted merely for the sake of illustration; that I do not intend to-suggest that the zoospores are evenly distributed through the water into which they are discharged by the zoosporangia; and ‘that allowance must be made for the very short life of those zoospores which do not speedily reach an appro- priate nidus. Nevertheless, the conclusion remains arithmetically certain that every diseased salmen adds immensely to the chances of infection of those which are not diseased; and thus, the policy of extirpating every diseased fish as soon as possible, has ample justifi- eation. But, in practice, the attempt to stamp out the disease in this fashion would be so costly that it may be a question whether it is not better to put up with the joss caused by the malady. There are many practical difficulties in the way of directly observing the manner in which the zoospores effect their entrance into the skin of the fish ; but, on comparing the structure of the healthy integument with that of the diseased patches, the manner of the operation can. 1882.] Epidemic known as the “ Salmon Disease.” 387 readily be divined. The skin of the head of a salmon, for example, presents a thin superficial cellular epidermis covering the deep fibrous and vascular derma. The epidermic cells are distinguishable, as in fishes in general, into a deep, a middle, and a superficial layer. In the first, the cells are vertically elongated, in the second more rounded and polygonal, in the third flattened. Many of the cells of the middle layer are of the nature of ‘‘mucous cells.” They enlarge and become filled with a mucous secretion; and, rising to the surface, burst and discharge their contents, which give rise to the mucous fluid with -which the fish’s body is covered. The openings of these “mucous cells” remain patent for some time and are to be seen in thin vertical sections. The hyphez of the spores which attach them- selves to the fish may enter by these openings, but even if they do not, the flattened superficial cells certainly offer no greater resistance than does the tough cuticle of a fly. However this may be, sections of young patches of diseased skin show that the hyphe of the fungus not only traverse the epidermis, but bore through the superficial layer of the derma for a distance, in some cases, of as much as one- tenth of an inch. Hach hypha thus comes to have a stem-part, which lies in the epidermis, and a root-part, which lies in the derma. Hach of these elongates and branches out. The free ends of the stem-hyphe rise above the surface of the epidermis and become con- verted into zoosporangia, more or fewer of the spores of which attach themselves to the surrounding epidermis and repeat the pro- cess of penetration. Thus the epidermis and the derma become traversed by numerous hyphe set close side by side. But, at the same time, these hyphe send off lateral branches which spread radially, forcing asunder the middle and deeper layers of the epidermic cells, and giving rise to the radiating ridges which are visible to the naked eye in the peripheral part of the patch. The force of the growth of the hyphz which traverse the epidermis, is made obvious by the curious manner in which, when the central tract of a patch is teased out, the distorted epidermic cells are seen adhering to it, as if they were spitted upon it. In the derma, the root-hyphez branch out, pierce the bundles of connective tissue, and usually end in curiously distorted extremities. The effect of the growth of the stem-hyphe is to destroy the epidermis altogether. Its place is taken by a thick, felted, mycelium, which entangles the minute particles of sand which are suspended in the water, and thus no doubt constitutes a very irritating application to the sensitive surface of the true skin. In the true skin, the tracks of the root-hyphe are not accompanied by any obvious signs of inflammation, but the hyphe are so close set, that they cannot fail to interfere with the nutrition of the part, and thus bring about necrosis and sloughing. Such sloughing in fact / 388 On the Epidemic known as the “Salmon Disease.” [ Mar, 2, gradually takes place, small vessels give way and bleed, and the burrowing sore, which is characteristic of the advanced stages of the disease, 1s produced. The skin of the head may thus be eaten away down to the bone and gristle of the skull, but I have not observed the fungus to enter these. On the scaly part of the skin, the fungus burrows in the superficial and in the deep layer of the pouches of the scales, but I have not observed the scales themselves to be perforated. When I found that the fangus penetrated the true skin, and thus gained access to the lymphatic spaces and blood-vessels, it became a matter of great interest to ascertain whether the hyphe might not break up into toruloid segments (as in the case of the Eimpusa musce), and thus give rise to general septic poisoning, or fungoid metastasis. However, I have never been able to find any indication of the occur- rence of such a process. : But a very important practical question arises out of the discovery - that the fungus penetrates into the derma. There is much reason to believe, that if a diseased salmon returns to salt water, all the fungus which is reached by the saline fluid is killed, and the destroyed epidermis is repaired. But the sea water has no access to the hyphe which have burrowed into the true skin; and hence it must be admitted to be possible, that, in a salmon which has become to all appearance healed in the sea, and which looks perfectly healthy when it ascends a river, the remains of the fungus in the derma may break out from within, and the fish become diseased without any fresh infection. It has not infrequently been observed, that salmon in their upward course became diseased at a surprisingly short distance from the sea, and it is possible that the explanation of the fact is to be sought in the revival of dormant Saproleqnia, rather than in new infection. It is to be hoped, that experiments, now being carried on at Berwick, will throw some lght on this point, as well as upon the asserted efficacy of sea water in destroying the fungus which it reaches. These are the chief results of this season’s observations on the salmon disease. Incomplete as they are, they appear to me to justify the following conclusions :— 1. That the Saprolegnia attacks the healthy living salmon exactly in the same way as it attacks the dead insect, and that it is the sole cause of the disease, whatever circumstances may, in a secondary manner, assist its operations. 2. That death may result without any other organ than the skin being attacked, and that, under these circumstances, it is the consequence partly of the exhaustion of nervous energy by the incessant irritation of the felted mycelium with its charge of fine sand, and partly of the drain of nutriment directly and indirectly caused by the fungus. 1882. | On the Conservation of Solar Energy. 389 3. That the penetration of the hyphe of the Saprolegnia into the derma renders it at least possible that the disease may break out in a fresh-run salmon without re-infection. 4. That the cause of the disease, the Saprolegnia, may flourish in any fresh water, in the absence of salmon, as a saprophyte upon dead insects and other animals. 5. That the chances of infection for a healthy fish entering a river, are prodigiously increased by the existence of diseased fish in that river, inasmuch as the bulk of Saprolegnia on a few diseased fish vastly exceeds that which would exist without them. 6. That, as in the case of the potato disease, the careful extirpation of every diseased individual is the treatment theoretically indicated ; though, in practice, it may not be worth while to adopt that treat- ment. II. “On the Conservation of Solar Energy.” By C. WILLIAM SIEMENS, D.C.L., LL.D.. F.R.S., Mem. Inst. C.E. Received February 20, 1881. The question of the maintenance of Solar Energy is one that has been looked upon with deep interest by astronomers and physicists from the time of La Place downward. The amount of heat radiated from the sun has been approximately computed, by the aid of the pyrheliometer of Pouillet and by the acti- nometers of Herschel and others, at 18,000,000 of heat units from every square foot of his surface per hour, or, put popularly, as equal to the heat that would be produced by the perfect combustion every thirty- six hours of a mass of coal of specifie gravity=1°d as great as that of our earth. If the sun were surrounded by a solid sphere of a radius equal to the mean distance of the sun from the earth (95,000,000 of miles), the whole of this prodigious amount of heat would be intercepted ; but considering that the earth’s apparent diameter as seen from the sun is only seventeen seconds, the earth can intercept only the 2,250-millionth part. Assuming that the other planetary bodies swell the intercepted heat by ten times this amount, there remains the important fact that 224999999 of the solar energy iy radiated into space, and apparently lost to the solar system, and only sys545555 utilised. Notwithstanding this enormous loss of heat, solar temperature has not diminished sensibly for centuries, 1f we neglect the periodic changes—apparently connected with the appearance of sun-spots—that have been observed by Lockyer and others, and the question forces itself 390 Dr. C. W. Siemens. [ Mar. 2, upon us how this great loss can be sustained without producing an observable diminution of solar temperature even within a human lifetime. Amongst the ingenious hypotheses intended to account for a con- tinuance of solar heat is that of shrinkage, or gradual reduction of the sun’s volume suggested by Helmholtz. It may, however, be urged against this theory that the heat so produced would be liberated throughout his mass, and would have to be brought to the surface by conduction, aided perhaps by convection; but we know of no material of sufficient conductivity to transmit anything approaching the amount of heat lost by radiation. Chemical action between the constituent parts of the sun has also been suggested; but here again we are met by the difficulty that the products of such combination would ere this have accumulated on the surface, and. would have formed a barrier against further action. These difficulties led Sir Wiliam Thomson to the suggestion that the cause of maintenance of solar temperature might be found in the circumstance of meteorolites falling upon the sun, not from great distances in space, as had been suggested by Mayer and Waterston, but from narrow orbits which slowly contracted by resistance until at last the meteorolites became entangled in the sun’s atmosphere and fell in; and he shows that each pound of matter so imparted would represent a large number of heat units without disturbing the planetary equili- brium. But in considering more fully the enormous amount of planetary matter that would be required for the maintenance of the solar temperature, Sir William Thomson soon abandoned this hypo- thesis for that of simple transfer of heat from the interior of a fluid sun to the surface by means of convection currents, which latter hypo- thesis appears at the present time to be also supported by Professor Stokes and other leading physicists. But if either of these hypotheses could be proved, we should only have the satisfaction of knowing that the solar waste of energy by dissipation into space was not dependent entirely upon loss of his sensible heat, but that his existence as a luminary would be prolonged by calling into requisition a limited, though may be large, store of energy in the form of separated matter. The true solution of the problem will be furnished by a theory, according to which radiant energy which is now supposed to be dissipated into space and irre- coverably lost to our solar system, could be arrested, wholly or partly, and brought back in another form to the sun himself, there to continue the work of solar radiation. Some years ago it occurred to me that such a solution of the solar problem might not lie beyond the bounds of possibility, and although I cannot claim intimate acquaintance with the intricacies of solar physics, I have watched its progress, and have engaged also in some 1882. ] On the Conservation of Solar Energy. 391 physical experiments bearing upon the question, all of which have served to strengthen my confidence and ripened in me the determina- tion to submit my views, not without some misgiving, to the touch- stone of scientific criticism. For the purposes of my theory, stellar space 1s supposed to be filled with highly rarefied gaseous matter, including probably hydrogen, oxygen, nitrogen, carbon, and their compounds, besides solid materials in the form of dust. This being the case, each planetary body would attract to itself an atmosphere depending for its density upon its relative attractive importance, and it would not seem unreasonable to suppose that the heavier and less diffusible gases would form the staple of these atmospheres ; that, in fact, they would consist mostly of nitro- gen, oxygen, and carbonic anhydride, whilst hydrogen and its com- pounds would predominate in space. But the planetary system, as a whole, would exercise an attractive influence upon the gaseous matter diffused through space, and would therefore be enveloped in an atmosphere, holding an intermediate posi- tion between the individual planetary atmospheres and the extremely rarefied atmosphere of the stellar space. In support of this view it may be urged, that in following out the molecular theory of gases as laid down by Clausius, Clerk Maxwell, and Thomson, it would be difficult to assign a limit to a gaseous atmo- sphere in space and, further, that some writers, among whom I will here mention only Grove, Humboldt, Zoellner, and Mattieu Williams, have beldly asserted the existence of a space filled with matter, and that Newton himself, as Dr. Sterry Hunt tells us im an interesting paper which has only just reached me, has expressed views in favour of such an assumption. Further than this, we have the facts that meteorolites whose flight through stellar, or at all events through interplanetary space, is suddenly arrested by being brought into collision with our earth, are known to contain as much as six times their own volume of gases taken at atmospheric pressure; and Dr. Flight has only very recently communicated to the Royal Society the analysis of the occluded gases of ore of these meteorolites taken immediately after the descent to be as follows :— CO i ee 0-12 CONC eae 31 88 ee ia 45 -79 CLA ee er A355 ee es ak 17-66 100 -00 It appears surprising that there was no aqueous vapour, considering there was much hydrogen and oxygen in combination with carbon, but 392 Dr. C. W. Siemens. [ Mar. 2, perhaps the vapour escaped observation, or was expelled to a greater extent than the other gases by external heat when the meteorolite passed through our atmosphere. Opinions concur that the gases found occluded in meteorolites cannot be supposed to have entered into their composition during the very short period of traversing our atmosphere, but if any doubt should exist on this head, it ought to be set at rest by the fact that the gas principally occluded is hydrogen, which is not contained in our atmosphere in any appreciable quantity. Further proof of the fact that stellar space is filled with gaseous matter is furnished by spectrum analysis, and it appears from recent investigation, by Dr. Huggins and others, that the nucleus of a comet contains very much the same gases found occluded in meteorolites, including ‘‘ carbon, hydrogen, nitrogen, and probably oxygen,” whilst, according to the views set forth by Dewar and hiveing, it also con- tains nitrogenous compounds such as cyanogen. Adversely to the assumption that interplanetary space is filled with gases, it is urged that the presence of ordinary matter would cause sensible retardation of planetary motion, such as must have made itself felt before this; but assuming that the matter filling space is an almost perfect fluid not lmited by border surfaces, it can be shown on purely mechanical grounds, that the retardation by friction through such an attenuated medium would be very slight indeed, even at planetary velocities. But it may be contended that, if the views here advocated regard- ing the distribution of gases were true, the sun should draw to himself the bulk of the least diffusible, and therefore the heaviest gases, such as carbonic anhydride, carbonic oxide, oxygen and nitrogen, whereas spectrum analysis has proved on the contrary a prevalence of hydrogen. In explanation of this seeming anomaly, it can be shown in the first place, that the temperature of the sun is so high, that such compound gases as carbonic anhydride and carbonic oxide, could not exist within him; it has been contended, indeed, by Mr. Lockyer, that none of the metalloids have any existence at these temperatures, although as regards oxygen, Dr. Draper asserts its existence in the solar photo- sphere. There must be regions, however, outside that thermal limit, where their existence would not be jeopardised by heat, and here great accumulation of those comparatively heavy gases that constitute our atmosphere would probably take place, were it not for a certain counterbalancing action. I here approach a point of principal importance in my argument, upon the proof of which my further conclusions must depend. The sun completes one revolution on its axis in 25 days, and its diameter being taken at 882,000 miles, it follows that the tangential velocity amounts to 1:25 miles per second, or to 441 times the Der 1882. ] On the Conservation of Solar Energy. 393 tangential velocity of our earth. This high rotative velocity of the sun must cause an equatorial rise of the solar atmosphere to which Mairan, in 1731, attributed the appearance of the zodiacallight. La Place rejected this explanation on the ground that the zodiacal light extended to a distance from the sun exceeding our own distance, whereas the equatorial rise of the solar atmosphere due to its rotation could not exceed =,ths of the distance of Mercury. But it must be remembered that La Place based his calculation upon the hypothesis of an empty stellar space (filled only with an imaginary ether), and that the result of solar rotation would be widely different, if it was supposed to take place within 2 medium of unbounded extension. In this case pressures would be balanced all round, and the sun would act mechanically upon the floating matter surrounding it in the manner of a fan, drawing it towards itself upon the polar surfaces, and projecting it outward in a continvous disk-like stream. By this fan action, hydrogen, hydrocarbons, and oxygen, are sup- posed to’ be drawn in enormous quantities toward the polar surfaces of the sun; during their gradual approach, they will pass from their condition of extreme attenuation and extreme cold, to that of com- pression, accompanied with rise of temperature, until on approaching the photosphere, they burst into flame, giving rise to a great develop- ment of heat, anda temperature commensurate with their point of dis- sociation at the solar density. The result of their combustion will be aqueous vapour and carbonic anhydride or oxide, according to the sufficiency or the insufficiency of oxygen present to complete the com- bustion, and these products of combustion in yielding to the influence of centrifugal force will flow toward the solar equator, and be thence projected into space. The next question for consideration is: What would become of these products of combustion when thus rendered back into space ? Apparently they would gradually change the condition of stellar material, rendering it more and more neutral, but I venture to suggest the possibility, nay, the probability, that solar radiation would, under these circumstances, step in to bring back the combined materials to a condition of separation by a process of dissociation carried into effect at the expense of that solar energy which is now supposed to be lost te our planetary system. According to the law of dissociation as developed by Bunsen and Sainte-Claire Deville, the point of dissociation of different compounds depends upon the temperature on the one hand, and upon the pressure on the other. According to Sainte-Claire Deville, the dissociation tension of aqueous vapour of atmospheric pressure and at 2800° C. is 0°5, or only half of the vapour can exist as such, its remaining half being found as a mechanical mixture of hydrogen and oxygen, but that with the pressure, the temperature of dissociation rises and falls, 394 Dr. C. W. Siemens. [Mar. 2, as the temperature of saturated steam rises and falls withits pressure. It is therefore conceivable that the temperature of the solar photo- sphere may be raised by combustion to a temperature exceeding 2800° C., whereas dissociation may be effected in space at compara- tively low temperatures. These investigations had reference only to heats measured by means of pyrometers, but do not extend to the effects of radiant heat. Dr. Tyndall has shown by his exhaustive researches that vapour of water and other gaseous compounds intercept radiant heat in a most remarkable degree, and there is other evidence to show that radiant energy from a source of high intensity possesses a dissociating power far surpassing the measurable temperature to which the compound substance under its influence is raised. Thus carbonic anhydride and water are dissociated in the leaf cells of plants, under the influence of the direct solar ray at ordinary summer temperature, and experiments in which I have been engaged for nearly three years* go to prove that this dissociating action is obtained also under the radiant influence of the electric arc, although it is scarcely perceptible if the source of radiant energy is such as can be produced by the combustion of oil or gas. The point of dissociation of aqueous vapour and carbonic anhydride admits, however, of being determined by direct experiment. It engaged my attention some years ago, but I have hesitated to publish the qualitative results I then obtained, in the hope of attaining to quantitative proofs. These experiments consisted in the employment of glass tubes, furnished with platinum electrodes, and filled with aqueous vapour or with carbonic anhydride in the usual manner, the latter being fur- nished with caustic soda to regulate the vapour pressure by heating. Upon immersing one end of the tube charged with aqueous vapour in a refrigerating mixture of ice and chloride of calcium, its temperature at that end was reduced to —32° C., corresponding to a vapour pres- sure, according to Regnault, of -~55 of an atmosphere. When’ so cooled no slow electric discharge took place on connecting the two elec- trodes with a small induction coil. I then exposed the end of the tube projecting out of the freezing mixture, backed by white paper, to solar radiation (on a clear summer’s day) for several hours, when upon again connecting up to the inductorium, a discharge, apparently that of a hydrogen vacuum, was obtained. This experiment being repedted furnished unmistakable evidence, I thought, that aqueous vapour had been dissociated by exposure to solar radiation. The CO, tubes gave, however, less reliable results. Not satisfied with these qualitative results, I made arrangements to collect the permanent * See “ Proc. Roy. Soc.,” val. 30, p. 208, and paper read before Section A, British Association, and printed in full in the Report for 1881, Part TI, p. 474. 1882.| On the Conservation of Solav Energy. — 395 gases so produced by means of a Sprengel pump, but was prevented by lack of time from pursuing the inquiry, which I purpose, however, to resume shortly, being of opinion that, independently of my present ‘speculation, the experiments may prove useful in extending our know- ledge regarding the laws of dissociation. It should here be observed that, according to Professor Stokes, the ultra-violet rays are in a large measure absorbed in passing through clear glass, and it follows from this discovery that only a small portion of the chemical rays found their way through the tubes to accomplish the work of dissociation. This circumstance, being adverse to the experiment, only serves to increase the value of the result observed. Assuming, for my present purpose, that dissociation of aqueous vapour was really effected in the experiment just described, and assuming, further, that stellar space is filled with aqueous and other vapour of a density not exceeding the 5,),,th part of our atmosphere, it seems reasonable to suppose that its dissociation would be effected by solar radiation, and that solar energy would thus be utilised. The presence of carbonic anhydride and carbonic oxide would only serve to facilitate the decomposition of the aqueous vapour by furnishing ‘substances to combine with nascent oxygen and hydrogen. It is not necessary to suppose that all the energy radiated from the sun into space should be intercepted, inasmuch as even a partial return of heat an the manner described would serve to supplement solar radiation, the balance being made up by‘absolute loss. To this loss of energy must be added that involved in keeping up the circulating movement of the gas, which, however, would probably not be relatively greater than that concerned in the tidal retardation of the earth’s rotation. By means of the fan-like action resulting from the rotation of the sun, the vapours dissociated in space would be drawn towards the polar surfaces of the sun, be heated by increase in density, and would burst into flame at a point where both their density and temperature had reached the necessary elevation to induce combustion, each "complete cycle taking, however, years to be accomplished. The resulting aqueous vapour, tarbonic anhydride and carbonic oxide, would be drawn towards the equatorial regions, and be then again projected into space by centri- fugal force. Space would, according to these views, be filled with gaseous com- pounds in process of decomposition by solar radiant energy, and the existence of these gases would furnish an explanation of the solar absorption spectrum, in which the lines of some of the substances may be entirely neutralised and lost to observation. As regards the heavy metallic vapours revealed in the sun by the spectroscope, it is assamed that these form a lower and denser solar atmosphere, not participating in the fan-like action which is supposed ,to affect the light outer atmosphere only, in which hydrogen is the principal factor. VOL. XXXII. ‘ 2G 396 Dr. C. W. Siemens. [Mar. 2, Such a dense metallic atmosphere could not participate in the fan action affecting the lighter photosphere, because this is only feasible on the supposition that the density of the in-flowing current is, at equal distances from the gravitating centre, equal or nearly equal to the outflowing current. It is true that the products of combustion of hydrogen and carbonic oxide are denser than their constituents, but this difference may be balanced by their superior temperature on leaving the sun, whereas the metallic vapours would be unbalanced, and would therefore obey the laws of gravitation, recalling them to the sun. On the surface of contact between the two solar atmo- spheres intermixture, induced by friction, must take place, however, giving rise perhaps to those vortices and explosive effects which are revealed to us by the telescope in the intermediate or stormy region of the sun, and which have been commented on by Sir John Herschel and other astronomers. Some of the denser vapours would probably get intermixed and carried. away mechanically by the lighter gases, and give rise to that cosmic dust which is observed to fall upon our ‘earth in not inappreciable quantities. Hxcessive intermixture would be prevented by the intermediary neutral atmosphere, the penumbra. As the whole solar system moves through space at a pace estimated vt 150,000,000 of miles annually (being about one-fourth of the velo- city of the earth in its orbit), it appears possible that the condition of the gaseous fuel supplying the sun may vary according to its state of previous decomposition, in which other heavenly bodies may have taken part. May it not be owing to such differences in the quality of the fuel supphed that the observed variations of the solar heat may depend ? and may it not be in consequence of such changes in the thermal condition of the photosphere that sun-spots are formed ? The views here advocated could not be thought acceptable unless they furnished at any rate a consistent explanation of the still some- what mysterious phenomena of the zodiacal light and of comets. Regarding the former, we should be able to return to Mairan’s views, the objection by La Place being met by a continuous outward flow trom the solar equator. Luminosity would be attributable to particles of dust emitting light reflected from the sun, or by phosphorescence. But there is another cause for luminosity of these particles, which may deserve a passing consideration. Hach particle would be electrified by gaseous friction in its acceleration, and its electric tension would be vastly increased in its forcible removal, in the same way as the fine dust of the desert has been observed by Werner Siemens to be in a state of. high electrification on the apex of the Cheops Pyramid. Would not the zodiacal light also find explanation by slow electric discharge backward from the dust towards the sun? and would the same cause not account for a great difference of potential between the sun and earth, which latter may be supposed to be washed by the solar 1882. | On the Conservation of Solar Energy. 397 radial current ? May not the presence of the current also furnish us with an explanation of the fact that hydrogen, while abounding appa- rently in space, is practically absent in our atmosphere, where aqueous vapour, which may be partly derived from the sun, takes its place ? An action analogous to this, though on a much smaller scale, may be set up also by terrestrial rotation giving rise to an electrical discharge from the outgoing equatorial stream to the polar regions, where the atmosphere to be pierced by the return flood is of least resistance. It is also important to show how the phenomena of comets could be ' harmonised with the views here advocated, and I venture to hope that these occasional visitors will serve to furnish us with positive evidence in my favour. Astronomical physicists tell us that the nucleus of a comet consists of an aggregation of stones similar to meteoric stones. Adopting this view, and assuming that the stones have absorbed in stellar space gases to the amount of six times their volume, taken at atmospheric pressure, what it may be asked, will be the effect of such amass of stone advancing towards the sun at a velocity reaching in perihelion the prodigious rate of 566 miles per second (as observed in the comet of 1845), being twenty-three times our orbital rate of motion. It appears evident that the entry of such a divided mass into a comparatively dense atmosphere must be accompanied by a rise of temperature by frictional resistance, aided by attractive condensation. At a certain point the increase of temperature must cause ignition, and the heat thus produced must drive out the occluded gases, which in an atmosphere 3000 times less dense than that of our earth would produce 6 xX 3000=18,000 times the volume of the stones themselves. These gases would issue forth in all directions, but would remain unobserved except in that of motion, in which they would meet the interplanetary atmosphere with the compound velocity, and form a zone of intense combustion, such as Dr. Huggins has lately observed to surround the one side of the nucleus, evidently the side of forward motion. The nucleus would thus emit original light, whereas the tail may be supposed to consist of stellar dust rendered luminous by reflex action produced by the light of the sun and comet combined, as fore- shadowed already by Tyndall, Tate, and others, starting each from different assumptions. These are in brief the outlines of my reflections regarding this most fascinating question, which I venture to put before the Royal Society. Although I cannot pretend to an intimate acquaintance with the more intricate phenomena of solar physics, I have long had a conviction, derived principally from familiarity with some of the terrestrial effects of heat, that the prodigious and seemingly wanton dissipation of solar heat is unnecessary to satisfy accepted principles regarding the conservation of energy, but that it may be arrested and returned over and over again to the sun, in a manner somewhat analogous GY 398 Lord Rayleigh. Value of the British Association [Mar. 9, to the action of the heat recuperator in the regenerative gas furnace. The fundamental conditions are :— 1. That aqueous vapour and carbon compounds are present in stellar or interplanetary space. 2. That these gaseous compounds are capable of being dissociated by radiant solar energy while in a state of extreme attenuation. 3. That these dissociated vapours are capable of being compressed into the solar photosphere by a process of interchange with an equal amount of reassociated vapours, this interchange being effected by the centrifugal action of the sun itself. If these conditions could be substantiated, we should gain the satis- faction that our solar system would no longer impress us with the idea of prodigious waste through dissipation of energy into space, but rather with that of well-ordered self-sustaining action, capable of per- petuating solar radiation to the remotest future. March 9, 1882. THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. The Right Hon. Anthony John Mundella, whose certificate had been suspended as required by the Statutes, was balloted for and elected a Fellow of the Society. The following Papers were read :— I, Experiments to Determine the Value of the British Associa- tion Unit of Resistance in Absolute Measure.” By Lorp RAYLEIGH, F'.R.S., Professor of Experimental Physics in the University of Cambridge. Received February 15, 1882. (Abstract. ) This paper contains an account of a repetition by Dr. Schuster, Mrs. Sidgwick, and myself, of the British Association experiment on the unit of resistance with an improved apparatus. Three distinct series of observations were taken, of which the two first were more or less imperfect. In the third series an extraordinary concordance in the results obtained on different occasions at the same speed of rotation was arrived at, but the numbers corresponding to the four speeds 1882. | Onit of Resistance in Absolute Measure. 399 could not be perfectly harmonized on the basis of an @ priori calcula- tion of the self-induction. Table VII.—Third Series. Wamber of teeth .0....% 26 3's 60. 45. ae 30. Mean. Resistance of standard at oa 23°619 | 23-621 | 23:°630 | 23-638 | 23 °627 13°, uncorrected. . \ 0-006 | 0-011 | 0-018] 0-025 Correction proportional to square of speed........ Resistance of standard at 612 13°, corrected... aa 23 °613 | 23°610 | 23-612 | 23-613 | 23-612 Table VII gives the results of this series. The “ number of teeth ”’ in the first row is inversely as the speed of rotation. The second row gives the resistance of a certain platinum-silver standard at 13° in absolute measure, as calculated with a value of the self-induction derived from evidence independent of the spinnings. The simple mean of these numbers is 23°627 (x10? C.G.S.), but they exhibit a well-marked tendency to rise with the speed. In the third row are numbers proportional to the squares of the speeds, by subtraction of which a practically perfect agreement is arrived at. The mean 23°612 thus represents the result of the investigation, if the effect of self-induction be determined from the spinnings themselves, and is to be preferred for reasons explained in the paper to the simple mean 23°627. The difference is, however, less than one part in a thousand. The resistance at 13° of the same coil in terms of B.A. units is 23°935, from which we find 1, 2A. ats = CORRE TL earth quadrant i second This number is somewhat lower than that which we obtained (9893) with the original apparatus,* but it agrees with that required to reconcile Dr. Joule’s thermal determinations. Rowland’s value is distinctly higher (9911), while Kohlrausch obtained 1°02. No satis- factory reconciliation of these results is arrived at, but some remarks are made upon the relative merits of the various methods. * “ Proc. Roy. Soc.,” vol. 32, p. 141. 400 Mr. A. Sanders. Anatomy of the | Mar. 9, II. “Contributions to the Anatomy of the Central Nervous System in Vertebrate Animals. Sub-section I. Teleostei. Appendix. On the Brain of the Mormyride.” By ALFRED SANDERS, M.R.C.S. Communicated by {Professor HUXLEY, LL.D., F.R.S. Received February 16, 1882. (Abstract.) The author, after a preliminary sketch of the literature of the sub- ject, and a description of his method of hardening and staining, proceeds to give an idea of the external aspect of the central nervous system in the Mormyride. Taking as an example the brain of the Hyperopisus dorsalis, he describes it as comparable to that of an ordinary teleostean fish to which two additions have been made, namely, an organ situated in the region in front of the cerebellum, which grows out in the form of plates, from a pair of stalks. These plates, or wings as they may be termed, become folded in every direction, and breaking through the tecta lobi optici, and repressing them to the base of the brain, they cover over all the remaining lobes of that organ. It is only the tecta lobi optici which undergo displacement, the tori semicirculares retain nearly their usual position, so as to become related to the former as an egg to the egg-cup, or an oyster to its shell. On the outer side of the plates are minute ridges running mostly longitudinally, in close proximity to each other ; the parts where these ridges become external are of a pinkish colour when fresh, but where the plates are folded on themselves, the inner side of the wings becomes external, and shows a white colour under the same circum- stances. These folds take place when the plates have grown sufficiently to reach the walls of the skulls, and are arranged as follows :—the plate which grows towards the anterior end of the skull turns backwards; that which grows towards the summit of the skull turns inwards; that which grows outwards turns upwards, while that which grows backwards ends in a free edge, and conceais the second of the addi- tional parts alluded to above. This exists in the form of a large nearly spherical tuberosity placed behind the cerebellum, in or over the region of the fourth ventricle. The author then gives an account of the microscopic anatomy of this brain. Passing lightly over the remainder of the lobes, which resemble in structure those of the ordinary teleostei, and noticing in passiug that the composition of the tecta lobi optici is much simplified, he proceeds to describe the structure of the cerebellum. He finds that o> Peg 1882.] Central Nervous System in Vertebrate Animals. 401 this presents the four layers usually found in the corresponding lobe in the teleostei, namely, counting from the outside, the molecular, the intermediate—which includes the Purkinjé cells—the granular, and the fibrous; the latter consisting of nerve-fibres on their way to the erura cerebelli. Noticing Denissenko’s* paper, and his discovery of two species ot cells in the granular layer of the cerebellum, the author remarks that he was unable to find them, even by using Denissenko’s own method. He then discusses the cause of the striation in the molecular layer, which he attributes in a great measure, but not entirely, to prolonga- tions from the epithelial layer of cells which cover the surface of the cerebellum. Incidentally he mentions that he has traced an axis cylinder process of a Purkinjé cell into a medullated nerve-fibre. He then goes on to describe the structure of the organ in front of the cerebellum. This he finds consists of two parts, a central con- tinuation of the cerebellum, having precisely the same structure and arrangement, and two lateral parts spreading out one on each side, like wings. | The plates which form these lateral wings consist of minute cells, resembling those found in the granular layer of the cerebellum. Hach ridge has four layers corresponding to those found in the cerebellum, arranged in a slightly different manner. The molecular layer comes first, then the granular and intermediate layers mingled together, and last of all, the fibrille from the fibrous layer. The molecular layers of contiguous ridges are placed in close contiguity with a process from the pia mater interposed between them; the granular and intermediate layers come next, consisting of cells of different sizes, connected together by a network of fibrille. The smaller cells resemble those of the granular layer of the cerebellum ; the larger ones are intermediate between the last, and the Purkinjé cells to which they lead up. These latter are arranged in a single layer; they are smaller in size than the corresponding cells in the cerebellum, and usually oval or fusiform in shape; they generally have two processes, one, the protoplasmic process, directed towards the molecular layer, and the other the axis-cylinder process, turned towards the bundle of fibrillee which is derived from the fibrous layer, and which, passing between two contiguous ridges on the side opposite the molecular layer, forms the boundary between them. In some parts, however, these cells are arranged in groups, Viz., where the bending of the wings causes bays and recesses in the ridges; here they are polygonal in shape and present several processes. The sides of the ridges are inserted into the plates or wings of granular layer cells, by conical processes. * “ Zur Frage ti. d. Bau d. Kleinhirnrinde,” “ Arch. f. Mik. Anat.,” Bd. xiv, 1877. 402 Central Nervous System in Vertebrate Animals. [Mar. 9,. The large tuberosity situated behind the cerebellum is termed by the author the tuberculum impar, and consists of six layers, counting” from the outside. 1. The first layer has small cells which become deeply coloured by the staining fluid. 2. The second contains sections of obliquely directed nerve-fibres. 3. The third is smoothly granular and does not become so highly coloured as the outside layer, but shows faint indications of radial striations. 4. The fourth is a narrow stratum of moderately sized cells of varying dimensions, which become intensely coloured by the staining: fluid. | 5. The fifth consists of a complex of nerve-fibres. 6. The sixth layer only found at the anterior end of the tubercle is. composed of finely granular material; the corresponding portion of the posterior end is occupied by a circular space. In addition to these six layers there is intercalated between the first and second layers a body of granular neuroglia, in which extremely large cells are collected; at the anterior end of the tuber- culum impar, this structure takes the place of the first layer and becomes interposed between the tubercle in question and the cere- bellum. The author then discusses the modes of origin of the nerves which are present in these fishes. The trochleares and the abducentes appear to be absent. The trifacial and the vagus, in addition to their ordinary origins, derive the greater number of their fibres from the tuberculum impar, the former from the anterior end, the latter from quite the posterior edge. The facial and the glossopharyngeal are parts of these two nerves respectively. The author finds, contrary to the opimion of Bellonci,* that the optic nerve has an origin from the hypoarium as well as from the tecta lobi optici. The other nerves arise as in Teleostei. The author then proceeds to indicate the probable homologies of these two extraordinarily developed organs. Taking the brain of a Ballan wrasse (Labrus maculatus) and examining the part which is. generally termed the valvula cerebelli, he finds that it has a central part resembling the cerebellum in structure, together with a wing on each side, occupying much more of the ventricle of the optic lobe than in many other Teleostei. These wings are formed by an extension of the molecular layer of the central part, which even here shows two or three folds based on an extension of the granular layer. He therefore puts forward the idea that if these wings of the valvula cerebelli of the LZ. maculatus: * “ Ueber d. Ursprung des Nervus Opticus und den feineren Bau des Tectum Op- ticum.” “ Zeitseh. f. Wiss. Zool.,’ Bd. xxxv, 1880. 1882.] On the Spectrum of Carbon. 403: were to continue to increase indefinitely, an organ resembling the highly developed structure in the Mormyridze would result. This latter then may be looked upon as homologising with the valvula cerebelli and its wings in the ordinary teleostean. With regard to the body which is placed behind the cerebellum, the author points out that the Cyprinide possess a well-known tuberosity occupying a corresponding position, which is termed by writers the tuberculum impar; this, in conjunction with the vagal tuberosities of the medulla oblongata, presents layers comparable to those existing in the structure in question belonging to the Mormy- ride; he therefore suggests that the homology of this exaggerated tuberosity in these fishes is to be looked for in the tuberculum impar together with the vagal tuberosities of the Cyprinide, the increased size in the former species having caused it to include the origin of the trifacial in addition to that of the vagus. In conclusion, the author offers some criticism of the ideas lately put forward by Fritsch* as to the homologies of the various parts of the brain in fishes, the key to the whole of which hes in his interpre- tation of the tecta lobi optici, which he takes to be the persistent cortex of the primary anterior vesicley of the brain of the embryo, and consequently to belong to the thalamencephalon, and not to the mesencephalon. In reply to this the present writer points out that the homologies of all the other parts of the brain in Teleostei may be deduced from the position of the pineal gland, the infundibulum, and the ganglion of origin of the oculomotorius. From this line of argument he maintains that the tecta lobi optici correspond to the anterior pair of the corpora quadrigemina, and con- sequently belong to the mesencephalon, and not to the thalamen- cephalon. Finally he remarks that the brain in Teleostei would not be in accordance with the remainder of their organisation, if all the parts of a mammalian cerebrum could be distinguished in it, even in _a comparatively rudimentary state as is maintained by Fritsch. III. “On the Spectrum of Carbon.” By G. D. Liveine, M.A.., F.R.S., Professor of Chemistry, and J. Dewar, M.A., F.R.S., Jacksonian Professor, University of Cambridge. Received February 23, 1882. The spectroscopic investigations we have communicated to the Society ‘‘On the Reversals of the Lines of Metallic Vapours,” have * “ Unters. i. d. feineren Bau des Fischgehirn.”’ Berlin, 1878. + “ Primires Vorderhirn,” loc. cit. A404 Profs. G. D. Liveing and J. Dewar. [ Mar. 9, shown the importance of a thorough and accurate knowledge of the ultra-violet spectra of the elements, for it is in the lines of short wave-length as a rule that the greatest emissive power is manifested, and they are therefore most readily reversed. Thus we have suc- ceeded in reversing upwards of 100 lines in the ultra-violet spectrum of iron (‘‘ Proc. Roy. Soc.,” vol. 32, p. 404). The necessity for accurate data in regard to this region of the spectrum led us to make a long study of the spectrum of magnesium, and the results of this investigation appeared in the volume of the “ Proc. Roy. Soc.” just cited. Having had occasion to examine the origin of the different fluted spectra of carbon, it became apparent that a complete knowledge of the relations of these spectra to the simple spectrum of the element could only be reached by the help of a complete record of the line spectrum. Angstrom and Thalén, in their memoir “On the Spectra of the Metalloids”’ (Nova Acta Ree. Soc. Upsal., Ser. ili, vol. ix), give a map and table of wave-lengths of the lines due to carbon in the visible part of the spectrum, as distinguished from the fluted spectra given by compounds of carbon, namely, carbonic oxide, cyanogen, and acetylene. These lines, they state, always appeared when very power- ful induction sparks were passed through the vapour of any compound of carbon, or between carbon electrodes. This line spectrum is remarkable for simplicity, consisting of eleven lines, of which the single line in the yellow, followed by a triple group in the green, and a very strong line in the blue, recall vividly the spectrum of magne- sium; and as we know two modifications of the spectrum of magne- sium which seem to be due respectively to the oxide and a hydride, the parallel between the behaviour of the two elements is the more striking. The plates of the ultra-violet spectra of the metals by the late Professor W. A. Miller (‘‘ Phil. Trans.,” 1864) include plates of the spark taken between metallic electrodes in different compounds of carbon, which show with sufficient clearness that there are some five groups of lines in the ultra-violet spectrum of this element. In the observations here described we have preferred taking intense induc- tion sparks between pure graphite poles in different gases. The accompanying figure represents the ultra-violet spectrum of carbon to a scale of wave-lengths within the range of the rays trans- mitted through calcite. The lines figured have been observed in photographs of the spark of a large induction coil, having a large Leyden jar in connexion with the secondary coil, between poles of purified graphite in air, carbonic acid gas, hydrogen, and coal-gas. ‘The same lines have been observed in photographs of the spark between iron, and between aluminium poles in carbonic acid gas. By comparing the photographs taken under these different circumstances, we have, we believe, eliminated the air lines, which are numerous and strong in the region between H and T, and will form the subject of a On the Spectrum of Carbon. = e) 2 oH a) >) pore fo) (oon fs 5 cy =) (2) fed) oF oD) 13) o —_ e) oS ye S al 45 5 406 Profs. G. D. Liveing and J. Dewar. [ Mar. 9, future communication, and also the metallic lines which graphite,. purified with the utmost care, still exhibited. The graphite was purified by being stirred in fine powder into: fused potash, and subsequent treatment with aqua regia, by prolonged: ignition in a current of chlorine, and by treatment with hydrofluoric: acid. The well washed powder was afterwards compressed into blocks by hydraulic pressure between platinum plates, and from these blocks the electrodes employed were cut. Notwithstanding the purification the photographs of the spark between these electrodes still showed very distinctly lines of magnesium and iron. This fact shows the extreme difficulty of getting rid of all impurity, and the caution which is requisite in any reasoning depending on the assumption of chemical purity in the materials employed. It is very possible that the magnesium and even the iron in this case may have been due to: oxides of those metals in the floating dust of the laboratory, which we know always contains sodium compounds, and which at Cambridge,,. where the water, soil, and bricks contain sensible quantities of lithium, almost always shows traces of that element. The wave-lengths of the strongest carbon lines were determined by means of a Rutherford diffraction grating having 17,296 lines to the inch. The measures were made in the following way: The collimator and telescope of the goniometer were first centred by the instrument maker’s marks. The telescope was then more carefully adjusted for centre by directing it on to a distant mark, taking the reading of the circle, turning the arm carrying the telescope through 180° and reversing the telescope, whereby the mark was again brought into the field of view, and adjustments were then made until the mark had the same position on the cross-wires in both positions of the telescope.. The grating was next placed in position, and, after adjustment to the vertical plane was brought very nearly at right angles to the axis of the collimator by turning it until the sodium D lines in the spectra of the second order were observed to fall at equal distances on either side of the collimator. The small photographic slide, containing the sensitive plate, fitted the telescope in place of the eye-piece, and so could easily be turned about an axis coincident, or nearly so, with the optic axis of the telescope. In taking a measurement of the position of a line the approximate wave-length was first found by interpolating between the nearest cadmium or other lines of known wave-length in photographs taken with calcite prisms. The telescope was then set to the angle corresponding to this approximate wave-length for the spectrum of the fourth order. The lower half of the slit was closed by a shutter, and the photographic slide having been adjusted for level, the plate was exposed to the light which came through the upper half of the slit, and gave an image of the lines in the lower half of the field. When this exposure was completed, the photographic 1882. ] On the Spectrum of Carbon. 407 slide was turned round through 180° about the axis of the telescope, so as to bring to the top that part of the sensitive plate which had been before lowest. It was then exposed a second time, and thus two images of the same line were impressed on the plate, which were necessarily at equal distances on either side of the point where the axis of the telescope met the plate. By a subsequent measurement with a micrometer under a microscope of the distance between the two images, and the conversion of this distance into angular measure, a correction was found, which was added to, or subtracted from, the reading of the circle to get the exact deviation of the ray producing the line under observation. Another photograph of the same line was next taken in the same way as before, except that the telescope was placed at the corresponding angle on the other side of the collimator. — From the two angles thus found, the wave-length of the line was calculated. The process was repeated three or four times for each line, and the mean wave-length thus found for carbon lines were 2296°5,- 2473°3, 2509°0, 2511°9, 2836°3, and 2837°2. The numbers deduced from the different photographs of the same line differed from one another in the last figure only, so that we are justified in assuming the first four figures to be accurate in each case. The wave-lengths of the remaining lines were obtained by interpolation from measures of photographs taken with a train of two calcite prisms of 30° each, and one of 60°, on which the iron as well as the carbon lines were shown. The wave-lengths of the iron lines used in the interpolations were deduced from photographs taken with the grating in the same way as that above described for the carbon lines. The wave-lengths thus found for the remaining carbon lines are given in the table below. In taking the photographs of the spark, the induction coil was sometimes worked by a De Meritens magneto-electric machine, and in that case the stream of sparks was not only extremely brilliant, but _ produced a deafening roar. Notwithstanding this character of the spark, the photographs, when the spark was taken in air, between poles of purified graphite, showed, besides the carbon lines above described, the set of six cyanogen flutings in the blue very distinctly, and those between K and bh, and those near N, strongly developed. On the other hand, when the spark was taken in carbonic acid gas, these flutings almost entirely disappeared, and would no doubt have disappeared entirely, if the last traces of air had been removed from the apparatus. AOS Profs. G. D. Liveing and J. Dewar. [ Mar. 9, Table of Carbon Lines. Authors. | Colour. Wave-length. Intensity. i ( 6583 ° Rede. {| 6577" 5694 ° 5660 ° 5646 ° Angstrém and Thalén... { 5638 ° Yellow... 5379 ° 5150 ° Green .. 5144 ° 5133 ° Indigo.... 4266 ° | =) Orange . OOW OOD WO HON OW Pe ODoOW + &E b 1, diffuse wy) Ne} a we) iN) 2, diffuse 4 3876 B ) ” 4, very diffuse 2995 ° 2968 ° 2837 ° 2836 - 2746 - 2733 - | 2640 - 4 2541 - ) 2528 ° 2523 - | 2518 ° 2515 - | | 2514: L WaAIwWwNndone bo 3, very diffuse 6, ) a9 A, 9 bP) Ultra- Liveing and Dewar..... { Boas | 2611: 2509 ° 2506 ° 2478 ° 2296 - NMIWAOCOONANWUN Ww eH OL bo OU C1 OL Oud Spectrum of Incandescent Carbon Filaments. We have also examined the spectrum of Swan’s incandescent lamps. So long as the carbon thread is unbroken, it emits a continuous spectrum, on which neither bright nor dark lines are visible. By gradually increasing the number of cells in the battery, until the thread gave way, we found at the instant of fracture, for a small fraction of a second only, that a set of flutings in the green appeared. In some of those lamps we observed, when the current was nearly as much as the carbon thread would bear without rupture, that a sort of flame appeared in the lamp. On examining the spectrum of this flame, it gave the flutings of carbonic oxide very distinctly, and we made sure that they were those of carbonic oxide, and not those of hydrocarbons, by comparison with the bands of a Bunsen burner. Closer examination showed that this flame was strongest about the junction of the carbon thread with one of the conducting wires, and 1882. | On the Spectrum of Carbon. ee), that on reversing the current, it shifted from one wire to the other, and the wire about which it appeared was always the positive electrode. In fact, the flame was the glow of the positive pole attending a discharge in rarefied gas; when the resistance of the carbon thread became too great in proportion to the intensity of the current, the discharge began to occur through the rarefied atmosphere within the envelope of the lamp. The spectrum showed that this atmosphere contained carbonic oxide. By interposing different flames between the incandescent lamp and the slit of the spectroscope, we have been able to make some compari- sons of the probable temperatures of the flames and filament. For this purpose a lens of 3 inches focal length was placed 6 inches in front of the slit, and an image of a horizontal part of the incandescent carbon thread formed by it across the (vertical) slit. The appearance in the field of view of the spectroscope was a narrow continuous spectrum extending all across the field. When a flame was interposed between the lens and the slit, the bright lines of the flame were seen above and below the narrow continuous spectrum, and in some cases were continued across it, or were seen reversed upon it. When the flame was that of a Bunsen burner in which was a platinum wire with sodium carbonate, the yellow sodium lines were seen bright above and below the continuous spectrum of the carbon thread, but reversed where they crossed it. When lhthium was substituted for sodium in the flame, the red lithium line was also seen bright above and below the continuous spectrum, but reversed where it crossed it. When an oxyhydrogen jet was substituted for the Bunsen burner, and sodium carbonate held in it, the yellow sodium lines were not only bright above and below the continuous spectrum of the carbon, but showed as bright lines where they crossed it, in fact they were con- spicuously brighter than the carbon. When coal-gas was substituted for hydrogen in the jet, the same appearance presented itself, only the sodium lines were not so much brighter than the carbon as they were before. Fifty Grove’s cells were used with the incandescent lamp, which were as many as could be used without danger of rupturing the threads. When barium chloride was held in the hydrogen flame fed with only a little oxygen, the bright green line of barium (wave-length 5534) was well seen above and below the continuous spectrum, but could not be traced either bright or dark across it. When a flame of cyanogen burning in air was interposed, the bright bands of that flame could be seen above and below the continuous spectrum, but could not be traced either bright or dark acress it. When sodium carbonate was held in this flame the yellow sodium lines were seen feebly reversed where they crossed the spectrum of the incandescent lamp. We infer from these experiments that the emissive power of the carbon thread for light of the refrangibility of the D lines is nearly a | A10 Dr. B. Stewart. | Mar. 9, balanced by that of sodium at the temperature of the flame of cya- nogen burning in air, but is sensibly less than that of sodium, at the temperature of a jet of coal-gas and oxygen, much less than that of sodium in the oxyhydrogen jet. This seems to render it probable that the temperature of the incandescent thread is not far different from that of a cyanogen flame burning in air (or rather the tem- perature it conveys to the sodium in it), but is less than that of an oxyhydrogen flame, though this does not necessarily follow from the experiments, inasmuch as the radiation of the sodium is so much more limited as to range than that of the carbon. When a Bunsen burner or a gas blowpipe flame was interposed between the Jens and slit, no reversal of the hydrocarbon bands could be seen. When magnesium was burnt between the lens and slit, the magne- sium lines (b) were seen bright, eclipsing the carbon. Possibly the smoke of magnesia may have considerably helped to eclipse the hight of the carbon. IV. “Prelimmary Report to the Solar Physics Committee on a Comparison for Two Years between the Diurnal Ranges of Magnetic Declination as recorded at the Kew Observatory, and the Diurnal Ranges of Atmospheric Temperature as recorded at the Observatories of Stonyhurst, Kew, and Falmouth.” By BAurour Stewart, LL.D., F.R.S., Pro- fessor of Physics at Owens College, Manchester. Com- municated to the Royal Society by permission of the Solar Physics Committee. Received January 25, 1882. 1. Ina paper communicated to this Society, and published in its ** Proceedings”’ (vol. 32, p. 406), evidence was brought forward tend- ing to show that what may be termed declination-range weather takes 1°6 days to pass from Toronto to Kew; that is, the same phase occurs 1:6 days later at Kew than at Toronto. And in a previous paper (op. cit., vol. 29, p. 508) evidence was brought forward tending to show that temperature-range weather takes about 8 days to pass between these two places. # In this last-mentioned paper an attempt was likewise made to show that there is a similarity between magnetical and meteorological changes, and that both are due to the sun. This result has been con- firmed by subsequent discussion, and there seems reason to suppose that in America both magnetical and meteorological changes follow very quickly after the solar changes which produce them. 1882.] Preliminary Report to the Solar Physics Committee. 411 If this be true, if the two kinds of allied weather start together at America, or nearly together, and if the magnetical moves in the same direction as the meteorological weather, but only quicker than it, then it is not unreasonable to suppose that the Kew magnetical weather of to-day may be found to resemble the Kew meteorological weather six or seven days later on. It is this point which I have endeavoured to test in the present communication by comparing together the variations of declination- range and those of temperature-range at Kew during the years 1871 and 1872. 2. Bearing in mind, however, the local nature of meteorological phenomena, instead of confining myself to Kew alone, I have taken | the means of the daily temperature-ranges at Stonyhurst, Kew, and Falmouth, these three forming the chief stations in England of the Meteorological Council, to whose kindness I am indebted for a list of the daily temperature-ranges at these three places for the years 1871 and 1872. These mean ranges have been compared with the corresponding Kew declination-ranges, excluding disturbances, for which I am indebted to the kindness of the Kew Committee. This comparison has been made after the following method :— 3. The meteorological material, as already mentioned, consists of a series of the daily temperature-ranges at Stonyhurst, Kew, and Falmouth, recorded in degrees Fahrenheit and tenths of a degree. As the results are merely comparative, decimal points have been omitted ; also, instead of taking means of the daily temperature-ranges at these three places, it has only been deemed necessary to record the sums of these ranges, thereby saving the division by three for each day. A specimen of these sums is exhibited in Table I, column 2. Further- more, in order somewhat to equalise or tone down individual fluctua- tions, daily sums of four of the numbers of column 2 are recorded in column 3. Again, as it is fluctuations of small period, say twenty-four or twenty- _ five days, which we wish to investigate, column 4 is made to contain means of twenty-five of the numbers of column 3, this mean being placed opposite to that number of column 3 which has the middle or thirteenth place in the series of twenty-five. Finally, the differences between corresponding numbers of columns 3 and 4 are exhibited in column 5, these being taken to represent the fluctuations we are in search of, the sign minus denoting defect, and the sign plus excess, in the observed values of column 3 with reference to the mean or normal values of column 4. 4. These various peculiarities of the method will be perceived foe the following table :— VOu. XXXII. mes 8h 412 Dr. B. Stewart. | Mar. 9, Table I.—Exhibiting the method of forming a series of Fluctuations of Temperature- Range. | Col. 1. ey a Col. 3. Col. 4. Col. 5. | ums 0 Sums of Means of : aes ranges 4. values 25 values a wee i F+K+S. | oof Col. 2. |) of Golls.0\ >of tame | January 1..... 244 s Dh See 185 963 CE te hae 263 1028 “ Ab Rea 271 1082 55 Bescsisce 309 1040 5 Gi eek 239 984: SNe Pres 221 908 a bi eens 215 958 EAH MTG N. Le | 233 1089 SeaLOie ec wees anise! Mer es | 352 1200 nile Rd enti a | 280 1158 ita eno | 279 1110 Fy ae otal 247 1091 993 + 98 ay w eh eke sea] 304 1131 986 +145 et i Gacore | 261 1132 975 +157 Sty VT | 319 1110 963 +147 ae ih ee 248 1038 Tang Gye eyes | 282 981 Peo ays | 189 944 | Lame on ay | 262 857 LW Di a 211 905 DE il oA 195 813 Sern eRe | 237 74d, ai aL Oaeiene 170 728 a eee ee 142 686 sie 2G Roe 179 768 ay fate ie ike: 195 757 RAs ob eae 252 787 Sao Os erehes 131 gis | Medi ese 209 | 5. The numbers representing the diurnal ranges of declination at Kew are derived by means of a measuring instrument applied to the magnetograph curves, and are recorded in decimals of an inch. As the results are merely comparative, decimal points have been omitted. These numbers have been treated in the same way in which the numbers in column 2 of the above table are treated; in fine, the tem- perature and declination-ranges have had applied to them precisely the same method of treatment. Ultimately we obtain, as in the case of the temperature-ranges, a column representing declination fluctuations, and comparable with column 5. 6. 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Sree SST VSM SOV G | nChVes aoa a aa Sanh Ney Key eS, es) fee) | PLEVe eee eo ss ee | far DEGAS NN UV4G | AAOG ee ‘y Report to the Solar Physics Committee. = | | | eoeoeer eevee 28 © 8 @ @ Ga = | | | “s ; Sea ale he ome ait] S ‘(ZL8T) | (S481) T].,.< een a ee Mg Reece ee) me are ee ee hae sep Ul PreMmioy < aL srl “ety [St IL ‘Ol Tr ‘OT 6) Of 6 ‘8 | “6 ‘8 ‘4 | 8 ‘4 ‘9 | LEO Sao) Cer Gabe: Gacallece coal seMareae woryeutpooqy = “STLJUOPL N \ a Be ee tae D A ° i [Z8] teod oy} 1OF (sAoqe sv) stg oredqos|W— TIT 9142], [Mar. 9, Dr. B. Stewart. A416 ils LOL PSCoL FO9GT SPS6L Po96L OdELG O6V LG COGTG ESVIE COVIS LV60¢6 TELLOL 6.0L 6.8 LOLGG GT6S6 LEC&S T6LE6 6 ‘By ‘ZZ8T avod oy} Loy (OAOGV SV) SUING [VOIVAqos|W— AT 2P[4¥L, a a a G6G1E SESE 8666E GVV ILE V1I90& op S— 6 2, 9 S861 LVGCE SS11 GOF6S EZ1LzZ ‘SU JUOTL GOOTE LOSZE L8GGE LLLOE O8G6G 9 ‘G F a a ee “gp GLOGL 6106 6EGLE 06806 OOGTL STZPI SPVPL ie Mioy poysnd uworyeurpoog ° ° GL Il OL ° e ° . e : jor) "step UL 1882.] Preliminary Report to the Solar Physics Committee. 417 7. The following are questions which suggest themselves with refe- rence to the numbers of Table II :— cb In the first place, do the inequalities of declination-range at all — correspond with those of temperature-range P and, secondly, if so, what is the difference in phase between the two sets of inequalities P y I shall endeavour to reply to the last question first. In order to do so, let us take any three months of temperature-range, and try to find how far it is necessary to push forward the declination-range numbers in order to obtain the maximum amount of correspondence between them and those of the temperature-range for the three months under consideration. This will be denoted by a maximum algebraic sum of the two inequalities ; in fine, we pursue precisely the same process as that adopted for ascertaining the difference of phase when comparing together the declination-ranges at Kew and Prague (‘‘ Proc. Roy. Soc.,” vol. 29, page 316). Now let us perform a number of such operations, taking various sets of three months each, so that the middles of the sets may corre- spond, as far as possible, to the middles of the various months between the beginning of 1871 and the end of 1872. 8. The results of this process are exhibited in Tables III and IV, in which, for shortness’ sake, the various months of the year are num- bered in order, instead of being named. 9. The results of Tables III and IV are conveniently embodied in the following table :-— Table V.—Showing by how many Days the Declination-range Fluc- | tuation precedes the corresponding Temperature-range Fluctuation. Precedence of Declination. Corresponding to middle of month. First year. | Second year. Mean. — ae | 8 8 “ 142) eee 6 | 4 5) NPE 0. wis. 20: 3 6 5) 5°5 April 5) 5 5 RR Yes e i sak or akiwias ave at.» 9 i) 9 June 9 9 9 io i Seale ee 12 | 11 11°5 RPPPMESTET Harz ats ale} s/o) «ial arta 13 13 13 ERIPEMIET! Seer acciielen RX ~ S 75) SS) S +. jc) > ~~ pe > oS o! “\—~ a aS Ss ~~ ~ '~= ~ —S Y love Ss 1882.] 420 Preliminary Report to Committee on Solar Physics. [Mar. 9, that were a considerable number of years so treated, more exact values. \.exhibiting the law would be obtained. The law itself is sufficiently obvious in each of the two years now treated. 10. It has still to be ascertained to what extent the two fluctuations, when brought together so that similar phases coincide as nearly as possible, show any distinct resemblance to each other. The evidence on this point is given by the diagrams which accompany this paper. These contain curves representing the continuous progress of the two sets of fluctuations for the years 1871 and 1872, these being F=portioned out into months. The temperature-range curve has a uniform time scale. The declination-range curve is pushed forward by a distance derived from the last column of Table V. Thus for January of each year it is pushed forward eight days, for February of each year five days, and soon. The consequence of this is that the declination-range scale, while constant for the various portions of the ,; same month, yet varies slightly from one month to another. ~ An inspection of the curves will show that there is a considerable likeness between them. Perhaps this likeness is greater in the second than in the first year, but it must be borne in mind that 1871 was a year of great magnetic disturbance, and therefore unfavourable for such a comparison. It would thus seem as if a comparison of magnetical and meteoro- logical weather might be made a promising subject of inquiry, besides ay being one which may perhaps lead to results of practical importance. Before concluding I beg to thank Messrs. William Dodgson and Alfred Nish for the assistance which they have rendered in this investigation. =< | 1882.] A.Mannheim. Centres de Courbure Principaur, §c. 421 . March 16, 1882. THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. Pursuant to notice given at the last Meeting of the Society, H.R.H. the Duke of Edinburgh was proposed by the President, and seconded by the Treasurer, for election and immediate ballot. The ballot having been taken the Duke of Edinburgh was declared duly elected a Fellow of the Society. The following Papers were read :— I. “Sur les Centres de Courbure Principaux des Surfaces Homofocales du Second Ordre.” By Lieut.-Colonel A. MANNHEIM, Professor in the Ecole Polytechnique. Com- municated by Dr. Hirst, F.R.S. Received March 4, 1882. Dans la séance du 19 Janvier, 1882, j’ai eu Phonneur de communi- quer a la Société Royale une note ayant pour objet de faire connaitre quelques unes des liaisons qui existent entre les éléments de courbure des surfaces homofocales 4 une surface donnée et les éléments de cette surface. Je me propose maintenant de démontrer quelques théoremes relatifs aux centres de courbure principaux des surfaces homofocales, et de faire voir comment sont liés géométriquement les six centres de cour- bure principaux des trois surfaces homofocales qui passent par un méme point. Je vais prendre, pour point de départ, les expressions des rayons de courbure principaux auxquelles je suis arrivé dans ma précédente communication ; c’est le seul emprunt que je ferai a ce travail. Je ne me suis pas astreint 4 conserver mes anciennes notations; je définirai tout ce que j’emploierai, de telle sorte que le travail actuel peut se lire indépendamment du précédent. Soient (H) et (O) deux ellipsoides homofocaux de centre 0. Menons au point 7 de (E) la normale N a cette surface. Appelons (H’) et (H’’) les hyperboloides homofocaux 4 (EH) qui passent par m, menons aussi de ce point les normales N’, N” 4 ces surfaces. Les droites N’, N” sont les axes de l’indicatrice de (E) en m, et les plans (N, N’), (N, N”) sont les plans des sections principales de (HE) 422 A.Mannheim. Centres de Courbure Principaux [Mar. 16, relatifs A ce point. Les six centres de courbure principaux des sur- faces (E), (H'), (H”) sont mj, pg sur N, w’), w’g sur N’, uw"), uw”, sur N”. Circonscrivons 4 (O) un céne dont le sommet soit m. Les axes de. ce cdne sont N, N’, N”. Le plan (N, N’) est le plan d’une section principale de ce cone; il coupe cette surface suivant deux génératrices qui font, avec N, un angle w. Le plan de la courbe de contact de ce cone, c’est-d-dire le plan polaire de im par rapport 4 (O), rencontre NG IN ON? aus poms ie lee En vertu de relations établies dans ma communication du 19 Jan- vier, on a:— jul ; ml’ Vy sya U : b] COS” @& Sin” w nl x mils a Wy mye 7 dou Lorsque lon prend d’autres surfaces homofocales que (O), on a d’autres points, tels que J, l', et si lon considére m 1, m’ I’ comme co- ordonnées d’un certain point du plan (N, N’), le leu de ce point, d’apres l’équation precédente, est la droite wy, 1’). Il résulte de la que :— Les droites, telles que 1 \’, enveloppent une parabole, elles déterminent sur N et N’ des segments [OGD ESTE SIS. Cette parabole touche N et N’ aux centres de courbure principaux py, 1’), relatifs a la section pr incipale CN, N’) des surfaces (HE) et (H') normales a N et N'. Ce que nous venons de dire pour le plan (N, N’) peut se répéter pour les plans (N, N’’), (N’, N”) et, dans chacun de ces plans on a une parabole. Les paraboles, qui sont dans les plans (N, N”), (N’, N"), touchent respectivement N et N’ aux centres de courbure py et p's des sections faites dans (EK) et (H’) par ces deux plans, qui sont menés par N”. La drovte us, u's est alors Vaxe de courbure* de la ligne d intersection de (EK) et de (H'). Nous verrons tout 4 Vheure que cet axe de cour- bure est tangente 4 la parabole qui est dans le plan (N, N’). Nous avons vu que les droites, telles que / 1’, déterminent sur N et N’ des segments proportionnels. Il en est de méme des droites telles que J 1'' relativement 4 N et N" ; nous avons donc ce théoréme :— Les plans polaires @un point m, par rapport & des surfaces homo- focales, déterminent sur les droites N, N', N", awes des cénes circonscrits a ces surfaces et dont le sommet est m, des segments proportionnels. * L’axe de courbure, relatif 4 un poe m d’une courbe gauche, est la perpendicu- laire éleyée au plan osculateur en m, & partir du centre de courbure de la courbe en ce point. La connaissance de laxe de courbure pour un point d’une courbe en- traine done pour ce point la connaissance du plan osculateur et du centre de courbure de cette courbe. 1882. ] des Surfaces Homofocales du Second Ordre. 423 Parmi ces plans polaires, il y a les plans (N, N’), (N, N”), (N’, N”) qui sont les plans tangents en m aux surfaces (EH), (H’), (H"), et les plans principaux des surfaces homofocales, qui sont les plans polaires de m, par rapport a celles de ces surfaces qui sont infiniment aplaties. — L’enveloppe de ces plans polaires est alors une surface développable tangente aces six plans. la trace de cette développable sur le plan (N, N’) est la parabole enveloppe des droites telles que /1', cette développable, qui est tangente au plan (N, N’), étant coupée par ce plan suivant une parabole est alors du 4° degré. Nous avons donc ce théoréme: Les plans polaires dun point m, par rapport a des surfaces hoivo- focales, enveloppent une surface (D) du 4° degré, qui est tangente aux plans principaux des surfaces homofocales, ainsi quwauxe plans principaux des cones de sommet m circonscrits a ces surfaces. Comme les paraboles suivant lesquelles la surface (D) coupe les plans (N, N’), (N, N”), (N’, N”), sont les paraboles dont nous avons déja parlé, on a ce théoréme : La développable (D), enveloppe des plans polaires de m, touche les droites N, N', N’’, aux six centres de courbure principaux de (E), (H’), (H”), et touche les plans (N N’), (N, N”), (N’, N”), suivant les axes de courbure des courbes d’intersection de ces surfaces prises deux a deuce. On voit bien maintenant pourquoi les axes de courbure de ces courbes sont tangentes aux paraboles, traces de (D), sur les plans om ON’), CN, N’’); GN’, N”). Par N', menons des plans tangents 4(O). Ces plans touchent le cone de sommet m circonscrit a cette surface suivant les deux généra- trices qui sont dans le plan de la section principale de ce cdéne, per- pendiculaires a N’. De 1a résulte que, par rapport a4 (O), ce plan, qui n’est autre que le plan (N, N”), est le plan polaire del’. De méme le plan (N, N’) est le plan polaire del” par rapport a la méme surface. ' Rapprochons indéfiniment (O) de l’ellipsoide (E) et nous arrivons a ce théoreme : La normale enm aVune des surfaces homofocales a pour polaire, par rapport a cette surface, Vaxe de courbures de la ligne intersection des deux autres surfaces homofocales qui passent en m. On retrouve aussi ce théoréme connu: Les centres de courbure principaux dune surface du second ordre en m sont les poles du plan tangent en ce point a cette surface par rapport aux deux surfaces homofocales qui passent par m.* Appelons a, b, c les points ot N perce les plans principaux des sur- faces homofocales. De méme, appelons a’, b’, c’, w”, b”, c les points analogues pour N’ et N”. Puisque les plans principaux sont des plans * Voir “ Treatise on the Analytic Geometry of Three Dimensions.” By George Salmon. 3rd edition. Page 151. A424 Sur les Centres de Courbure Principaux, §c. [Mar. 16, tangents ala développable (D) les droites aa', bb’, cc’, sont tangentes a la parabole trace de (D) sur le plan (N, N’). Comme cette parabole est tangente a N au centre de courbure jm, on voit que: Le centre de courbure y,, de la section faite dans (EK) par le plan (N, N’), est placé sur N, par rapport aa,b, c, comme le point m est placé sur N', par rapport dab, ce’. Ce que nous disons pour ce centre de courbure peut se répéter pour les autres. De 1a résultent, pour ces points, différentes constructions que je ne crois pas nécessaire de développer. Des points J, 1’, 1, ot l'un des plans polaires de m rencontre N, N’, N”, élevons respectivement des plans perpendiculaires 4 ces normales. Ces trois plans se coupent en un point X. Puisque les plans polaires de m déterminent sur N, N’, N” des segments proportionnels, nous voyons que: Les points, tels que X, relatifs aux plans polaires de m par rapport aux surfaces homofocales, sont en ligne droite. Nous désignerons cette droite par A; on peut la construire en employant deux plans principaux des surfaces homofocales qui sont deux plans polaires particuliers de m. Prenons le plan (N, N’) pour plan de la figure 1. Marquons sur N et N’ les points a, b, ¢, a’, b’, c’ ou ces droites rencontrent les plans principaux des surfaces homofocales. Sur N et N' nous avons les centres de courbure principaux fy, 7. D’aprés ce que nous avons vu, la parabole tangente a aa’, bb’, cc’, N, N’ touche ces dernieres droites aux points 4), #). Les points a, a’ sont alors les projections sur N et N’ d’un point de la corde de contact fy #1. Deméme ponr 8, 0’ etc, c’. Pour avoir sur N le centre de courbure jo, nous devons prendre un 1882.] Photographic Spectrum of the Great Nebula in Orion. 425 point qui soit placé par rapport 4 a, b, ¢ comme le point m est placé sur N’* par rapport 4a’, 6”, c'’. Le point p»’, s’obtient de la méme maniére sur N’. Les points »: et »’, sont alors aussi les projections sur N et N' d'un méme point de la corde de contact py, 1’). La droite «x, u', est done tangente 4 la parabole comme nous I|’avions déja trouve. Les segments ab, a’b', sont les projections sur N et N’ d’un segment de mu, “’), qui, lui méme, est la projection sur le plan (N, N’) du segment de A, qui se projette sur N’” en a” b”. Ce segment de A rencontre le plan (N, N’) au point de py, »’, qui se projette sur N et N’ en py et p’o. Ce que nous venons de trouver en considérant le plan (N, N') peut se repéter pour les plans (N, N’’), (N’, N”). De tout cela résulte cette propriété qui établit une Haison trés simple entre les six centres de courbure principaux de (EK), (H’), et). Trois surfaces homofocales du second ordre se coupent en un point m. Les normales a ces surfaces en ce point sont N,N’. N”’. Ces normales rencontrent les plans principaux des surfaces homofocales, la premiere en a, b, c, la deuxiéme ena’, b’ c’, e¢ la troisiéme ena’, b", c'’. On éléve respectivement de ces points des plans perpendiculaires a ces normales. Les plans issus des points a, a’, a'’ se coupent en un certain point. On obtient de méme un point pour b,b’, b'' et wn troisieme point pour c, ce’, c.” Ces trois points appartiennent a une méme droite A. Les projections de A, sur les plans détermines par les normales N,N’, N”, prises deux a deux, rencontrent ces normales aux centres de courbure principaux des trois surfaces homofocales. Ces centres de couwrbure sont alors aussi les projections sur les normales N, N’, N”’, des points ou A perce les plans détermines par ces normales prises deux a deux. La droite, qui joint les projections sur deux de ces normales du point o& A perce le plan de ces droites, est Vaxe de courbure de la ligne d’intersection des surfaces homofocales normales a ce plan. II. “ Note on the Photographic Spectrum of the Great Nebula in Orion.” By Wiiuiam Hueerns, D.C.L., LL.D., F.R.S. Received March 9, 1882. Last evening (March 7) I succeeded in obtaining a photograph of the spectrum of the great nebula in Orion, extending from a little telow F to beyond M in the ultra-violet. The same spectroscope and special arrangements, attached to the 18-inch Cassegrain telescope with metallic speculum belonging to the * N” n’est pas sur la figure, ni les points a”, 8”, ¢”’. 426 Dr. W. Huggins. On the Photographic F | 4 5 l Firtuvalimliuti 45 A6 47 45 vvtimlrmaliettimlin 44 buvvslarunlvvrttunielann t un 43 — — — — ———d — —_ — : ell [Mar. 16, allied 1882. | Spectrum of the Great Nebula in Orion. A27 Royal Society, were employed which have been described in my paper on “ The Photographic Spectra of Stars.” * The exposure was limited by the coming up of clouds to forty-five minutes. The opening of the slit was made wider than during my work on the stars. The photographic plate shows a spectrum of bright lines, and also a narrower continuous spectrum which I think must be due to stellar light. The bright stars forming the trapezium in the “ fish’s mouth” of the nebula were kept close to the side of the slit, so that the light from the adjacent brightest part of the nebula might enter the slit. Outside this stronger continuous spectrum I suspect an exceedingly faint trace of a continuous spectrum. In the diagram which accom- panies this paper the spectrum of bright lines only is shown, which is certainly due to the light of the nebula. In my papers on the visible spectrum of the nebula in Orion, and other nebule,f I found four bright lines. The brightest line, wave- length 5005, is coincident with the less refrangible component of the double line which is strongest in the spectrum of nitrogen. The second line has a wave-length of 4957 on Angstrém’s scale. The other two lines are coincident with two lines of hydrogen, Hf or F, and Hy near G. In the photograph these lines which had been observed in the visible spectrum are faint, but can be satisfactorily recognised and measured. In addition to these known lines the photograph shows a relatively strong line in the ultra-violet, which has a wave-length 3730 or nearly so. The wide slit does not permit of quite the same accuracy of determination of position as was possible in the case of the spectra of stars. For the same reason [ cannot be certain whether this new line is really single, or is double or multiple. In the diagram this line is represented broad to indicate its great relative intensity. This line appears to correspond to ¢ of the typical spectrum of white stars.t In these stars this line is less strong than the hydrogen line near G; but in the nebula it is much more intense than Hy. In the nebula the hydrogen lines F and Hy are thin and defined, while in the white stars they are broad and winged at the edges. The typical» spectrum has been added, for the sake of comparison, to the diagram. I cannot say positively that the lines of hydrogen between Hy and the line at 3730 are absent. If they exist in the spectrum of the nebula, they must be relatively very feeble. I suspect, indeed, some very faint lines at this part of the spectrum, and possibly beyond 4 3730, but I am not certain of their presence. I hope by longer ex- * “Phil. Trans.,’’ 1880, p. 672. + Ib., 1864, p. 437, and 1868, p. 540. Also “ Proc. Roy. Soc.,” vol. 14, p. 39, and vol. 20, p. 380. ¢ “ Phil. Trans.,” 1880, p. 677. VGL. XXXIII. 21 428 Profs. G. D. Liveing and J. Dewar. { Mar. 16, posures and with more sensitive plates, to obtain information on this and other points. It is, perhaps, not too much to hope that the further knowledge of the spectrum of the nebule afforded us by photo- graphy, may lead by the help of terrestrial experiments to more definite information as to the state of things existing in those bodies. III. “On the Disappearance of some Spectral Lines and the Variations of Metallic Spectra due to Mixed Vapours.” By G. D. Liveine, M.A., F.R.S., Professor of Chemistry, and J. Dewar, M.A., F.R.S., Jacksonian Professor, University of Cambridge. Received March 11, 1882. The theory’ of spectral lines most commonly received is that the otions of the luminiferous ether producing them are not directly due * to any motion of translation of the molecules of the emitting substance, but to relative motions of the parts of the same molecule, or in other words, to vibrations occurring within the molecules; and that the mutual action of the molecules, while it may give rise to irregular vibrations of the ether, affects the regular vibrations producing the lines only in an indirect manner, by converting part of the motions of translation into internal vibrations. On this theory the spectral lines which any given substance can readily take up will in general be limited to a certain number of fundamental lines and a number of others harmonically related to them, though not necessarily simple harmonics of the fundamental lines. And variations of temperature, by altering the rapidity and the violence of the action of one molecule on another, will alter the intensities of the several vibrations, but not their periods, unless the violence should extend to the disintegration of the molecules, which would be equivalent to the formation of new molecules with new fundamental periods of vibration. In view of this theory, the observations on the spectrum of magnesium have a special interest, because from the close analogy of magnesium to zine and cadmium, it is inferred that the molecules of magnesium vapour are chemical atoms of that substance, that is to say, they pass appa- rently undivided through all the chemical changes to which magnesium may be subjected; and it seems reasonable to suppose that any sub- division of the chemical atoms could not fail in this case to be attended with a change of chemical qualities, which, in the presence of other elements, would give rise to new compounds. No such new com- pounds have in fact been detected. We have already described in detail the differences between the spectra of magnesium as seen in the flame of the burning metal, the electric arc, and the spark discharge, and we have now some further observations upon them to place before the Society, which are confirmatory of the received theory. 1882.] On the Disappearance of some Spectral Lines, &¢. 429 We have observed the spectrum of a block of magnesia, rendered incandescent by an oxyhydrogen jet. In the visible part of this spec- trum we found no discontinuity, no lines bright or dark (except the inevitable D lines), no sign of the blue channelled spectrum of magnesia. Drs. Huggins and Reynolds (“ Proc. Roy. Soe.,” vol. 18, pp. 547, 551) have recorded the appearance of the 6 group under these circumstances, but we failed to get sight of it. In the ultra-violet region photographs still show a continuous spectrum, extending far beyond the limit of the solar spectrum, in factjas far as we have hitherto observed any lines of magnesium to occur, but on this con- tinuous spectrum one line, and only one, comes out, which is the ‘strongest line of burning magnesium and of the are spectrum, at wave- length 2852 (2850 Cornu). This line shows sometimes bright, some- times reversed, against the continuous background. In this case, where the appearance of the lines depends on their relative brightness, as compared with the continuous spectrum, there is no advantage, so far as the visible rays are concerned, in the photographic method over that of observation by the eye; there may be a disadvantage, as the photograph presents only the mean result of acertain time. But where the faint lines of a discontinuous spectrum are in question the photo- graphic method has the advantage, for when the vibrations are too feeble to produce any sensible impression on the retina, they may yet, ‘by integration of their effects during a lengthened exposure, produce a definite effect on the photographic plate. In general we have only exposed our plates for such times as would give us the best defined images, so that very faint lines are not developed in them; but by using a prolonged exposure we find that in many cases the disappear- ance of lines from the arc or spark is more apparent than real, and is attributable to a variation of intensity, not to an absolute cessation of the vibrations corresponding to the evanescent lines. Thus of the quadruple group between wave-lengths 2789 and 2802 in the spark spectrum of magnesium only the stronger two lines are usually seen in photographs of the arc with short exposure, but the whole fozr produce their impressions on the plate if sufficient time be given. Again, the triplet in the are spectrum at wave-length about 2942— 2937°5 is not usually seen in the spectrum of the spark, but when the plate has had a lengthened exposure the strongest two lines of this triplet make their appearance in the spectrum of the spark. Even the triplet near M, so strong in the flame of burning magnesium, but not before recognised either in the are or spark in photographs taken with short exposure,* comes out in plates of the spectrum of the Spottiswoode induction spark (if we may give this name to the method of stimulating the induction coil by the intermittent current of a * Dr. Huggins has informed us that his old photographs of the magnesium spark taken with an induction coil in the ordinary way show this triplet distinctly. Doe, 430 Profs. G. D. Liveing and J. Dewar. [Mar. 16, magneto-electric machine, see “‘ Proc. Roy. Soc.,” vol. 30, p.175) between magnesium electrodes which have had four or five minutes’ exposure. These observations tend to confirm the theoretical view that alterations of temperature cannot put a stop to any of the fundamental vibrations of a molecule; at the same time we cannot be sure that the impulses communicated by an electric discharge may not be in some respects different from those resulting from mere increment of temperature. There is, however, a further point for consideration, which is, how far the presence of a mixture of molecules of different elements affects the respective vibrations. This is a condition which obtains in most or all of our observations of the arc in crucibles, as well as in the solar atmosphere, so that it is important to see if any effects can be traced to such a condition of matter. Indeed, in order to arrive at any probable explanation of the variations observed in the spectra of sun-spots and of the chromosphere, we require to study the pheno- mena produced by such mixtures of vapours as exist in our crucibles, and not merely the spectra produced by the isolated elements, either in arc, spark, or flame. It is only on some such supposition as that above suggested that we can account for the absorption lines produced by admixtures of mag- nesium with sodium and potassium respectively (“ Proc. Roy. Soc.,” vol. 27, p. 353); and it is possible that the very remarkable effect of hydrogen in producing the reversal of chromium lines (#., vol. 32, p. 405) and of other lines (7b., vol. 28, p. 472) 1s a result of analogous action. We have more particularly observed the effect of a current of hydrogen on the iron lines at wave-lengths 4918, 4919°7, and 4923. These lines, as seen in the are in a mag- nesia crucible, usually have about me same relative strengths as are shown in Angstrom’ s map of the solar spectrum; Thalén gives their intensities as 2, 1, 3 respectively. They are all developed simultane- ously when iron . dropped into the crucible, the first being sometimes reversed, the second frequently reversed for some time, the third much strengthened but not reversed. After a time these effects die out, but if now a very gentle current of hydrogen is led in through one of the carbons perforated for the purpose, the line at 4919-7 is again strongly reversed, that at 4918 expanded, while that at 4923 becomes very bright but remains sharply defined. These effects of the hydrogen were observed several times. Inall cases the line at wave-length 4923 seemed to maintain about the same relative strength compared with the other two lines, and never showed any variation at all correspond- ing to the prominence it holds in Young’s catalogue of chromospheric | lines, where it has a frequency of forty, while that at 4918 has only | half that frequency, and the strongest line of the three does not figure | at all.* 7, * Mr. Lockyer’s figure (“ Proc. Roy. Soc.,”’ vol. 32, p. 205) accompanying his | 1882.] On the Disappearance of some Spectral Lines, &c. 431 Some further observations on this group of lines are contained in the sequel. The effects of mixtures of metallic vapours in developing bright lines are equally marked, and in general more easily observed. We have before noticed (‘“ Proc. Roy. Soce.,” vol. 30, p. 97) “ that certain lines of metals present in the crucible are only seen, or come out with especial brilliance, when some other metal is introduced. This is the case with some groups of calcium lines which are not seen, or barely visible, in the arc in a lime crucible, and come out with great brilliance on the introduction of a fragment of iron, but are not developed by other metals such as tin.” Effects of this kind are most frequent in the case of metals which produce a large number of lines. They are ‘specially noticeable in the case of nickel and titanium. Both these metals produce many lines, but a comparatively large quantity of nickel may be introduced into a crucible of magnesia, through which the are of a powerful Siemens dynamo-electric machine is passing, without the lines of nickel being strongly developed; they show steadily as sharp but not specially bright lines; but after several other metals—iron, chromium, &c.—have been put in in succession, the nickel lines frequently come out with great brilliance and considerably -expanded, and remain so for a long time. The titanium lines are generally very persistent when that metal (as cyanide or oxide) has been introduced into the crucible, but are subject to continual varia- tions of intensity; sometimes they are twinkling, at other times steady; but they can frequently be brought out with great brilliance by dropping in iron or other metals. In such cases the metals put into the arc can hardly be supposed to increase the resistance or the temperature, but they may assist the volatilisation of each other, and may also act by reduction, and so by increasing the incandescent mass strengthen the weaker lines. Chlorides, however, which seem to have the effect of helping the volatilisation and diminishing the resistance so that the arc can be drawn out to a greater length, usually sweep out the fainter lines. In many cases when a fragment of a metal is dropped into the cruci- ble brilliant lines, hitherto unrecorded, come out for a short time and quickly die out. It is hardly possible in such cases to say without prolonged observations whether these lines belong to the newly intro- duced metal or to some of those previously put in and developed by the presence of the new metal. How much remains to be done in the study of these lines, and how much light this may throw on the phenomena of the solar lines, will be seen from the following account of our observations of some very small portions of the spectrum of the paper on the spectra of sun-spots showing ‘‘ what happens with regard to three ad- _jacent iron lines under different solar and terrestrial conditions,” is at variance with -our observations, in so far as the line at 4923 is represented as absent from the are. 432 Profs. G. D. Livemg and J. Dewar. _—s[Mar. 16,. arc im a magnesia crucible. The portions selected are of special interest, because in these regions a remarkable outburst of broad Fraunhofer lines, not usually visible, is recorded by the Astronomer: Royal as having occurred in a sun-spot (‘‘ Monthly Not. Ast. Soc.,’” — 1881). Fig. 1 shows the principal (not all the) lines which were in the same field of view when the spectrum of the 4th order produced by a Rutherford grating (17,296 lines to the inch) was observed, the ight being that of the arc of a Siemens machine in a magnesia crucible. A small piece of copper was first put in and then some nickel, and by the lines of these metals the portion of the spectrum under examina-- tion was identified. The iron lines were as usual also present. The: symbols affixed to the several lines show those which came out when the metals indicated were introduced. Thus, when chromium was dropped in, a very brilliant line came out near the middle of the field, a little below the iron line wave-length 5090°4; titanium cyanide brought out a line at about wave-length 5086, cobalt one at 5094, uranic oxide: one at 5087, and cerium (which may have contained lanthanum and didymium) a number of lines. These lines were very bright for a second or two, and soon became much less brilliant, but were revived when more of the metal was put in. Lead brought out a very evanescent diffuse band represented in the figure by dotted lines. The distances of the several lines from the extreme nickel lines: were measured hastily by a micrometer, and are here reproduced to: — scale. One line at wave-length 5096, though constantly present, did not seem to be affected by any of the metals introduced. An iron line is indicated on Angstrém’s map at this place, but the introduc-. tion of iron, which expanded the neighbouring line at wave-length 5097°3, had no effect on it. ‘It is remarkable that this region in Angstrém’s normal solar spectrum is particularly bare of lines, though Vogel gives several faint lines between those marked by Angstrém. It is, however, a region in which many lines have been observed in sun-- spots (Greenwich Spectroscopic and Photographic Results, 1880), and the most prominent of these lines seem to correspond to lines developed by cerium, chromium, and cobalt, though more exact measures than we were able to take at the times that those observations were made are needed in order to establish an exact coincidence. Fig. 2 represents the lines brought out in a similar way in another short portion of the spectrum, which is also remarkably bare of lines in the solar spectrum. | Fig. 3 shows lines brought out in another place by the several’ metals indicated. Other lines were visible in this region but were: not specially developed by the metals introduced. The line at wave-length 4923, which occurs so often in the chromo-- 1882.] On the Disappearance of some Ce; Te “Ba CC. Ne COKE Te CO Fe >. FE Sa s Sit NM Tt CO FtCn. “NEST KOC: FC CF FE ie Tr ‘PE Ua CGS Lt Cr Mn Cé €e Bere Le. C€ 434. On the Disappearance of some Spectral Lines, &c. [Mar. 16, sphere, according to Young and Tacchini, and is assumed to be due to iron, is so near to lines which come out in our crucibles on the in- troduction of other metals, that we cannot help feeling some doubt as to its absolute identification with the iron line; the more so as in Young’s catalogue bright lines are sometimes assigned to two metals, of which the real lines differ by nearly a unit of Angstrém’s scale. This is the case, for example, with the line at wave-length 5017-6, which is ascribed to iron and nickel. And where lines are broadened, as in sun-spots, the identification with either of two very close lines becomes very difficult. Fig. 4 shows the lines which come out in the neighbourhood of wave-length 4923. A pair of lines are developed by iron close to this line, and a very bright but evanescent line comes out at about 4923°5, on the introduction of cerium. This is an exceedingly brilliant line for the time, and might easily be mistaken for the iron line unless examined under high dispersion, and it seems to show that metallic cerium is readily volatile under these conditions. The iron line at 4923 seems to disappear on the addition of titanium, which, on the other hand, brings out the lines marked titanium in the figure. Nickel brings out the cerium line strongly. The line which comes out at 4921°3 on the addition of chromium and titanium is most likely the line seen by Young in the chromosphere thirty times, which up to the present time has not been recognised as due to any element but sulphur. 3 Both the nickel line at 5016°5 and the adjacent iron line at 5017°5 are seen in the arc in our crucibles, but the nickel line is much the stronger and more persistent. Cerium when put into the crucible brightens the titanium lines, as well as the line at 5017°5. An. alloy of manganese, iron, and titanium had the effect of making the nickel line broad and diffuse, without strengthening the 5017°5 line. These are but samples of the large amount of work which remains to be done before we can pronounce that any of the solar lines are not due to terrestrial elements, or can draw any safe inferences from observed variations in their relative strengths or apparent coincidences ; and no real scientific advance can be made by attempting generaliza- tions with the knowledge which we at present possess. 1882.] Mr. 8. A. Hill. On Radiant Heat. A35 March 23, 1882. THE PRESIDENT in the Chair. The Presents received were laid on the table and thanks ordered for them. The following Papers were read :— I. “ On the Constituent of the Atmosphere that Absorbs Radiant Heat. Il.” By S.A. Hix, Meteorological Reporter, North- West Provinces and Oudh. Communicated by General STRACHEY, R.E., C.S.L, F.R.S. Received March 10, 1882. General Strachey has suggested to me that with the data given in my first paper we may arrive at a numerical relation between the absorptive powers of dry air and aqueous vapour, instead of being content with merely showing that vapour is by far the most active constituent of the atmosphere in this respect. The following calcula- tions, worked out on the lines suggested by him, indicate that the dry air has a small and, as far as we can judge, invariable effect in the way of absorption, while the effect of water vapour is large and variable. In other words, the air probably exercises a feeble absorption over the whole range of the spectrum, while the absorption due to water vapour is selective, and probably varies in amount with the nature of the radiation from day to day. Starting with Pouillet’s formula r=R Xx p’, where e stands for the atmospheric thickness and p for the fraction of the total radiation that would penetrate vertically through an atmosphere of unit thickness, we may take p to be made up of two factors, « and 8, one of which represents the diathermancy of the dry air and the other that of vapour. The masses of dry air and water vapour traversed by the rays will be respectively proportional, though not in the same ratio, to the barometric pressure* and the vapour tension. Taking the length of an oblique ray through any atmospheric stratum to be proportional to sec z, we thus arrive at the formula log r=log R+5 sec z log «+/fsec z log B, in which « and £ stand for the fractions of the total heat transmitted through atmospheres composed respectively of dry air and aqueous * That is to say, approximately proportional to the total pressure. It will not do to deduct the vapour tension from the total pressure, because the vapour thins out as we ascend much more rapidly than the air does. 436 Mr. 8S. A. Hill. On Radiant Heat. [ Mar. 23, vapour, and which, with the law of vertical distribution defined by the simultaneous observations at Mussooree and Dehra, would each produce a pressure equal to one inch of mercury. From the observations of the 12th November, 1879, given at page 218 of my previous paper, we get the following equations :— : Mussooree.... 23°533 x 2°304 log a+ °221 x 2:304 log B= — 09463, Wehrant ee 27°832 x 2292 log 2+°375 x 2:292 log B= —:14238 ; and from the observations of the 14th we get :— Mussooree. .. 23°529 x 2°339 log 2+ °183 x 2°339 log B= —-102293, Wehirac. c.1.7.6 27°825 x 2°330 log 2+ 302 x 2°330 log B= —*151972. These give the following results :— Date. a. B. l—«. 1—f. g Doi sheer ae a "99856 °76030 -00144 -°238970 L4ith 2/3. ayet 99855 °69536 ‘00145 30464 The absorption due to dry air of one inch pressure seems therefore to be almost invariable and equal to only *1445 per cent. of the total radiation—a quantity that could hardly be measured in laboratory experiments; while that due to water vapour of equal pressure varies between 24 and 30 per cent. (perhaps between much wider limits) and is equal, on the mean of the two days’ observations, to 27°217 per cent. In an atmosphere of dry air at 30 inches pressure the absorption would be 1—2*°, or about 44 per cent. of the total radiation. The fraction of the total heat that is absorbed by dry air, though in most cases very small in comparison with that absorbed by the vapour, seems therefore to be an appreciable quantity, and, if the tension of vapour at sea- level were only + of an inch or less, the dry air would have the greater effect of the two. Since the quantities of air (Q) and vapour (Q,) in a vertical column b C of given sectional area are in the ratio Qe ° x”) where C and QF ae C, are the constants of the logarithmic formule for vertical distribu- tion, the absorptive powers for equal masses of the two gases will be 1445 15, 26106 1 27°217° 8 66218 764-4 764-4 times the absorptive power possessed by air for the kind of radia- tion emitted from the sun on the 12th and 14th November, 1879. Asa very large proportion of the total solar radiation is luminous, and since water, both in the liquid and in the gaseous state, transmits the greater part of the luminous radiation, the relative diathermancy of dry air for radiant energy proceeding from sources at a lower tempera- ture must be very much greater still. in the ratio Water vapour has, therefore, 1882.| On the Influence of Coal-dust in Colliery Explosions. 437 I regret that, up to the present, I have been unable to procure a record of any other actinometrical observations that would serve to test the correctness of these results. II. “On the Influence of Coal-dust in Colliery Explosions. No. IV.” By W. GALLoway. Communicated by Ropert H. Scott, F.R.S. Received December 29, 1881. 3 In the concluding pages of No. III paper, now in the hands of the Royal Society, I described an apparatus the essential parts of which consist of a wooden gallery about 126 feet long by 2 feet square, and a sheet iron cylinder about 6 feet long by 2 feet in diameter; and, at the same time, I gave a short general account of the experiments that had been made with it up to that date, intending to resume the subject on some future occasion. It will be remembered that the experiment was made by mixing together and igniting a small quantity of fire-damp and air in the sheet iron cylinder called the “explosion chamber’’; that the resulting explosion burst through a paper diaphragm which separated the explosion chamber from the wooden gallery and created an air-wave; that the air-wave in passing through the gallery swept up coal-dust from the floor and from certain shelves placed at given points in it; and, lastly, that the flame of the original fire-damp explosion traversed the cloud of coal-dust and air to a greater or less distance from the origin. During the warm dry weather prevailing between the 14th and 21st of July last, I made sixty-three further experiments, which for convenience may be separated into the three following well-defined eroups. I. Fifteen to ascertain how far the flame of the mixture of fire- damp and air contained in the explosion chamber would extend along the wooden gallery in the absence of every trace of coal-dust. II. Thirty-eight to ascertain how far the flame produced in the same manner and under the same conditions as in the preceding case would extend into a cloud of coal-dust and pure air, created by the action of the air-wave in its passage through the wooden gallery. III. Ten to ascertain the effects due to the explosion of small heaps. of blasting powder placed at given points in the wooden gallery, all the other conditions being exactly the same as in the last case. In each experiment the fire-damp was carefully and accurately measured by water displacement in a special cylinder called the measuring cylinder in the two preceding papers. No fire-damp could enter any part of the apparatus without first passing through the measuring cylinder, and being thence transferred into the explosion chamber. As has been previously stated, also the explosion chamber — 438 Mr. W. Galloway. | Mar. 23, was separated from the wooden gallery by certain sheets of paper interposed between them in the form of a diaphragm. None but sheets without visible flaws were employed for this purpose, and they were inserted in the joint between the wooden gallery and the explosion chamber in such a way that their edges projected into the open air all round about. Seven minutes or so elapsed from the time the fire-dammp was begun to be transferred into the explosion chamber until its mixture with air was ignited. The largest quantity of fire- damp employed in any one of the sixty-three experiments was 1°876, or say, 2 cubic feet, and if even one-half of this quantity had escaped there could have been no explosion, as the mixture remaining in the explosion chamber would not have been inflammable. Admitting, however, for the sake of argument, that, in every case, one cubic foot of fire-damp passed through each sheet of paper in the diaphragm in succession and found its way into the gallery, then its rate of escape would be, say, one-seventh of a cubic foot per minute. But, during the whole time the first forty-two experiments were in progress, there was a current of fresh air amounting to upwards of 1,000 cubic feet per minute constantly passing into the gallery immediately behind the diaphragm and traversing it towards its open end. ‘Therefore, the greatest amount of fire-damp which the gallery could possibly have contained at any moment before one of these explosions was effected, even in the extreme case I have imagined, and with the further supposition that all the doors were shut, was about one-fourteenth part of a cubic foot, giving a mixture of one of gas to seven thousand of air, a proportion which is obviously far too small to be of the least practical account. ? It appears necessary to give the foregoing explanation, inasmuch as, in a report on some experiments made with dust from Seaham colliery,* Professor Abel has made the following remarks regarding the experiments conducted with the smaller apparatus described to the Royal Society in 1879, and whatever applies to those experiments in this respect, applies with equal force to the present ones, which are nothing more than their continuation on a larger scale. At page 5, Professor Abel says,—‘‘ The apparatus devised by Mr. Galloway for the latter experiments was very ingenious, but it appears open to question whether small quantities of fire-damp did not find their way before the explosion from that part of the apparatus where the gas- mixture was prepared and fired into the channel where the coal-dust was raised, and into which the flame of the explosion was projected.” The coal-dust employed in this series of experiments came from the * Report on the result of experiments made with the samples of dust collected at Seaham Colliery in compliance with the request of the Secretary of State for the | Home Department, conveyed by a letter dated November 4, 1880. By F. A. Abel, C.B., F.B.S., &e. 1882.] On the Influence of Coal-dust in Colliery Explosions. 439 same source as that used in most of the former ones. It had been produced in the operation of grinding coal for coke-making purposes, and had floated in the air and been deposited in a still atmosphere within the building containing the machinery. I could not obtain the results described in my previous papers, and in the present one, with dusi taken from screens, or from the roadways of mines; for, on the one hand, the dust from screens seems to have lost its finest particles before being deposited; and, on the other hand, the feeble nature of my explosion prevented me from attempting to perform the winnowing operation to which [imagine the dust in mines is subjected before it is required to propagate the flame of an explosion. It is an indispensable condition that the dust be dry, and I have found also that the best experimental results can only be obtained in fine dry weather. For instance, on the 20th of July, when it was warm and dry, I succeeded in producing flames of coal-dust and pure air varying in length from 108 to 147 feet; but on the 22nd, only two days afterwards, when it rained occasionally, and the air contained very finely divided moisture in the form of a light and hardly percep- tible mist, I could not produce a flame even 36 feet long. In making the series of experiments corresponding to the ones we are now discussing, which were described in No. II paper, I found that when the gallery was air-tight, or nearly so, the flame could not be propagated further than 30 or 40 feet from the origin; whereas, when the seams between the boards were open, the flame travelled 80 or 90 feet under the same conditions as before. The dry weather which had prevailed before the 14th of July last had dried up the timber of which the gallery was formed to such an extent as to pro- duce twelve open seams in it longitudinally, varying from 3” to }” wide; and it was recognised after the seventeenth experiment had been made, that this circumstance allowed the force of the fire-damp explosion to be dissipated, without forming an air-wave of sufficient energy to raise the coal-dust in the gallery. Accordingly, strips of wood were nailed along the seams on the top, on the doors, and on the back, while some of the succeeding experiments were in progress; strips of canvas were nailed along the seams on the floor; the spaces between the ends of the sections were carefully closed, and canvas was nailed along the joints between the doors and the gallery, with the object of making it as air-tight as possible everywhere. This opera- tion was completed. as far as the end of the sixth section, when the thirty-eighth experiment was made. ‘The experience in this case was that the more air-tight the gallery could be made the better were the results. When the twenty-eighth experiment was made, it first became evident that the gas and air in the explosion chamber had not been sufficiently well mixed in the preceding experiments to produce the 440 Mr. W. Galloway. (Mar. 23, best possible results by their explosion: Accordingly, in all the suc- ceeding experiments the driving wheel was turned rapidly 200 times instead of 100 times as before, the attendants relieving each other at the work, and, thereafter, the results were much more uniform, and, consequently, more satisfactory. It will be recollected from the account given in No. III paper, that the gallery consists of seven sections, and that each section has a door 18 feet long by 2 feet 3 inches wide, which constitutes one of its sides when it is closed (see sections a and J, fig. 3). When all the doors are open the gallery has only three sides—namely, top, bottom, and back, and its interior is exposed to view from one end to the other. The doors then stand out horizontally on a level with the top to which they are hinged, while their free edges are supported on suitable props. The table given below shows how many doors were shut,-and how many were open when each experiment was made, the shut ones being, of course, those nearest the explosion chamber. In one or two experiments, however, there were three doors next the explosion chamber closed, the following three open, and the last one shut. This was the case, for example, in the sixty-third experiment. There is no provision in the table for showing this arrangement, and as the flame did not, on any of these occasions, extend to the last section, it was not considered worthy of a special column. Hach of the seven sections contained coal-dust in the cases referred to, and that is the reason why they are all represented in the table. There were sets of three shelves, one above the other, placed trans- versely in the gallery at the following points, measured from the diaphragm towards the open ena: 10 feet, 21 feet, 32 feet 6 inches, 42 feet, 56 feet, 65 feet, 76 feet 4 inches, 87 feet, 96 feet 8 inches, 107 feet, and 117 feet 6 inches. The spaces between the shelves of each set, and between the highest and lowest shelf and the top and bottom of the gallery, were intended to have an approximately equal area. The shelves were about 6 inches wide by ? inch thick. Those heaps of powder referred to in the table, whose distances from the diaphragm correspond to the position of certain of the sets of shelves, were in these instances placed on the top shelf, the others were laid on the floor. After each experiment the coal-dust was entirely swept out and replaced by fresh dust, except in one or two cases which are specially mentioned in the table. The diaphragm usually consisted of six single sheets of newspaper, but the exceptions are shown in the table. Where a note of interroga- tion occurs the number of sheets may be taken as six, although the real number was omitted in taking notes at the time. Fig. 1 shows the length of flame (measured from the diaphragm) obtained in the principal explosion of each group. 1882.] On the Influence of Coal-dust mn Colliery Explosions. 441 Fre. 2. I. The average length of fourteen fire-damp flames (12 feet 8 inches) is shown by the dotted line AB.* II. The average length of fifteen flames of coal-dust and pure air (118 feet 6 inches) is shown by the line CD. III. The average length of five flames of coal-dust and pure air, augmented by the explosion of small heaps of gunpowder (145 feet), is Shown by the line HI. All the experiments between the fifteenth and thirty-first are omitted, as they were made while the apparatus was in an imperfect condition. In fig. 2 the apparatus is reproduced on a very small scale, so as to show its whole length, as well as the appearances presented by some of the more remarkable flames as they issued from its side, or end. The part which represents the explosion chamber is on the left hand side of the zero line, and the seven sections of the wooden gallery are on its right hand side. The form of the flames was sketched at the instant of their occurrence, with the exception of No. 59, which is correct as to length, and approximately correct as to its other dimensions, but was not sketched until afterwards. The average length of fire-damp flame obtained in the first fifteen experi- ments is shown on each representation of the apparatus by means of * After the additional precautions for obtaining a better mixture of the gases, d&c., had been introduced, several experiments of this class were made. But as it was found that the fire-damp flame was, if anything, shorter than before, sometimes not exceeding eight or nine feet in length, I did not think it necessary to undertake a new series of experiments, and allowed the original one to remain intact. AA? Mr. W. Galloway. [ Mar. 23, Ere. 2. el 40 1/50 16/0 UND WHAT a | Ese: Wi a D tet DTMTNNYD D Cary -srtes 1 FIREDAMP EXP OSIO|IN COALDUST] FL ME black lines drawn across the white ground. As the coal-dust flames issued from the apparatus they assumed various forms according to the direction in which the wind happened to drift the cloud of coal- dust and air which preceded them. Nos. 39 and 58 were bent back- wards, as the wind was biowing against the open end of the gallery at the time; Nos. 45 and 59, on the contrary, were drawn out in the same line as the gallery, the wind favouring that development; the others are more or less doubtful. Fig. 3 is aside view and two sections of the gallery on a larger scale than the last. The bands of iron which hold the wood-work jie 3} 1882.] On the Influence of Coal-dust in Colliery Explosions. 443 together and the supports on which the sections rest are also shown. In section (a) the door is open, in (0) it is shut. All important details concerning each experiment will be found in the following table :— Details of Sixty-three Experiments made at Lluyuypia Colliery, between the 14th and 21st of July, 1881. Position and weight Length of the gallery Distance travelled by — Date. a b 2 strewed with coal-dust. Baars the flame. Bia |5 : Tae es ae a ies ol ~ . B/ ERIE Sa eons als se| g e|e21a. ‘ F ‘ F o 8 We oo I¢ od 5 July,| 6 | £& | | |Sections with|Sections with] g ae} 2 Ba |e2 |ca | 8 1881.| % | 5.2 | S 2 | doors shut. | doors open. | $a |S fon os | Sa] 3 q|ea| ge Sa|s4| Ss igo siges| g2| 3s 138) 3s Bs |2e|ee estes oS | € Z2\/a5 |uc Fa l(/Ad|S5 SSassal asl! a Cb. ft.) No. | No Ft. | No Ft. | Oz Ft Ft Ft Ft. Ft ee u\1-si| 4 a ee 4 Le ; om |) LOfe (2 k-th | Oss mel 211-811) 6 5] Riel (ae a3 Ove As: S| 31-811] 6 Pe milie oe ES | aro vo! IP 10 al 4\i-sii| 6 Be aa | Sak a if) al eee eae a! ciate Pei 51-811, 6 abi tee ae . Tol NE Peni | Ba eo 6 |i-sil| ‘6 “ ind Ms Tee hee nam ls een a ae. Be 7 \1-S11| 6 Ee ; i 12 Er lbele Pe siti-sil| 6 3 Uy ae me eee Teel) aloe hs OMG Selo |1-e11| 6 Y i elt TG (ne (ieee arts {lo {1-s11| 6 ws ae Ns, 5 Neh ee | ee Berit |1-s11| 6 Beale tice Hilt eos dine pet wil = 112 11-s11| 6 i cil bane A | A ae eee Ree Ne 12 Seis iigi1| 4 ee a ee 1g (ere (Me Been aT TE! 15 14 /1°811 6 “ce s06 sec eee ? =00 =05 Ps M15) 1-sii| 6 We) || eas eee fe uae 13 ena) rite |i=gi1|° |? 3 | 54 2 | 36 ee tee eS ? meu ty|i-ei1| 2 3 | 54 2 | 36 Pete: ? eis i -sit) ? ay Ei PW Sh secs 1g | 18 36t ap 19 }1°811 ? 2 36 2 36 36 26 62 nA 20 51°811 6 3 54 2 36 a ? “5 21 }1°8il 6 3 54 2 36 54 5 5 59 “5 2a \ 1°81) 2 3 54 2 36 54 one 54 “: 23 |1°876 6 3 54 2 36 54 24 78 » | 24|1°876| 6 3 | 54 a is eed (Polke liste soar 46 In BG mt ath ib 80 op 25 | 1°876 6 3 54 2 36 500 roc 260 54 30 ses 84 a 26 | 1°876 6 3 54 2 36 ? 50 500 ? 55 27 | 1°876 6 3 54 2 36 54 + eee 58 », | 28 |1°876| 6 3 | 54 Dl BYR 54 | 27 81 Ar 29 |1°876 6 3 54 2 36 54 38 c 92 “ye 30 | 1°876 6 3 54 2 36 : 54 32 > 86 18 31 | 1°876 6 3 54 2 36 54 44 > 98 + 32 | 1°876 6 4 72 2 36 sae P 36 5 108 sp 33 |1°876 6 4 72 2 36 - 72 32 104 9 34 |1°876 6 ea 712 2 36 12 32 104 P35 |1-sic| 6 5 | 90 2 | 36 a ge ? » | 3611-876] ? 5 | 90 2 | 36 90 | 27 117] a 37 | 1°876 6 5 90 2 36 oer 90 36 2 128 19 38 | 1°876 6 5 90 2 36 é 90 1G 1009 i 39 | 1°876 6 5 90 2 36 ocr 90 36 4 130 “i 40 | 1°876 6 6 | 108 1 18 108 9 ons 117 * No coal-dust, and gallery wetted in the first fifteen experiments. * Fan going and upwards of 1,000 cubic feet of air passing into the apparatus just behind the dia- phragm until the forty-third experiment. t It was now recognised that the open seams in the gallery ought to be closed, and this operation was effected gradually with strips of wood and canvas, &c., until the thirty-first experiment, when it was completed except along the bottom and at the joints of the doors, where the seams were left open. § Strips of canvas were nailed along two of the three seams in the bottom and along the joints of the doors of the first two sections. Also pieces of felt were introduced between the ends of the first four ' doors this day. | Fresh dust was put into the first three sections only. @ Before experiments were begun this day strips of canvas were nailed along all the seams in the bottom and at the joints of the doors as far as the end of the sixth section. WOn.- XXXIII. Bt Tee 444 Mr. W. Galloway. [Mar. 23, Date.| = Length of the gallery Sern ae separ Distance travelled by g b 2 strewed with coal-dust. gunpowder. the flame. Q, Ss o4 a » cs o . 5 Br a 3 g E 3 sp] 8 July,| 6 | &] = |Sections with Sections with| ¢ &g |] a 22 5g aq 8 1881.) & | 38 ‘© © | doors shut. | doors open. | & Sie coupons mS as me 00 a a|sz| #4 Sa|s2|8s |Sos\225| 52] 3 £|S8| 32 OS | 2 Sul o8 je 2S S aes Ales|as PelAs|25 |SSSS88 ms] a Cb. ft.| No. | No. | Ft. | No. | Ft. | Oz Ft Ft Ft Ft. | Ft. 19 |} 41 | 1-876 6 6 | 108 1 18 ie : ? a cee ?* » | 42 /1°876] 8 6 | 108 1 18 ? ia et ? 3 | 43 |1-876 6 6 | 108 1 18 108 18 15 | 141 » | 44 11-876 6 6 | 108 1 18 ? ses acc et » | 45 |1°876 6 6 | 108 1 18 108 18 Bp |) alee » | 46 11-876 6 6 | 108 1 18 ? ees ‘ 5 20 | 47 11-876 6 6 | 108 1 18 ? joc : ? » | 48 11-876 6 6 | 108 1 18 ot £ a ? 15 | 49 | 1-876 6 4 72 3 54 72 50 payer || we ” 50 11-876 6 5 90 2 36 90 36 x6 126 » | Ol |1°876] 6 6 | 108 1 36 108 18 21 | 147 » | 52 | 1-876 6 © \e126 a8 wes 5S 85 abe 108 pe eos 19 | 93 |1°876 6 UG || We ses bs 3 ioe es ? Se aes ? 9 7 » | 54 ]1-876| 6 | 5 | 90 364] 9 -| o> [ony ho | a6) | ae ame — ” L not |) | 35 18 burnt 21 | 55 | 1-876 6 U || AS or ae ) 3 386 | burnt] +126] ... 27 «| 153 mo §| not ie = 72) burnt (F 1 { not oe ts burnt not » | 5611-876] ? 7 | 126 aq 2 | eae || tp 2 § | not te 2 W2 burnt} J Sova elcSiio) ame ||) 126 : Per 4 21 | burnt} 126 22 | 148 = ( 4 21 =| burnt > » | 58 |1-876| ? 7 | 126 yi a lee al eee 4126 g | 134 + 21 =| burnt os 59 | 1°876 6 7 | 126 a0 fl + 42 burn| 212 34 | 160 + 65 | burnt + 21 burnt ) = + 42 | burnt 1», | 60 |1°876 6 26 s ri 65 puree f 2 ? || 4 87 | burnt 4 21 | burnt 9 By Wola 876) 6s Het 7a s120 gu liere “| rae vet ? ere = 87 | burnt a uCG2 | Ucs7eile 4G 4 72 3 54 ¥e be oe ? oe ? » | 68 |1°876 6 3 54 4 72 ar Bes 54 46 cect th LOOSE * It was raining when the forty-first and forty-second experiments were made. + Rain had ceased when the forty-fourth experiment was made. t This result was obtained without putting in any fresh dust after the previous experiment was made. § The gallery had not been swept out, and no fresh dust was added after the last experiment. The soot was taken off the first and third heaps of powder, that had been left unburnt, and another heap was substituted for the one that had been burnt in the middle. || In this case and the next the explosion of the powder seemed to arrest the progress of the flame, instead of accelerating it. @ There was fresh dust in the two first sections only. ** This flame came out of the last two sections and swept the ground, coking the dust lying at the three points it touched over an area of four or five square feet at each. It should again be mentioned that a thick cloud of coal-dust and air was always created by the air-wave which emanated from the fire- damp explosion and swept through both the closed and open parts of the gallery, in advance of the flame. When this cloud emerged into the open air, either by drifting sideways from the open sections, or by 1882.] On the Influence of Coal-dust in Colliery Explosions. 445 being projected beyond the end of the gallery, it occasionally assumed large proportions, and the flame, which afterwards shot into it, also pecame enlarged until it appeared to have a diameter varying from 5 to 9 feet on different occasions. It then emitted a loud roaring sound and exhibited all the phenomena of incipient explosive combustion. Crusts of coked coal-dust were found adhering to the edges of the transverse shelves farthest from the explosion chamber, and their opposite edges were covered with a thin deposit of soot and dust, which had a velvety feeling when touched. These circumstances seem entirely to corroborate the hypothesis first proposed in No. I paper, in connection with Llan Colliery explosion, and afterwards revived in No. III paper, in connexion with Penygraig Colliery explosion, to the effect that the crusts of coked coal-dust are, asa rule, deposited during the retrograde movement of the air, that is to say, while it is travelling backwards towards the origin of the explosion. The results stated in the foregoing pages strengthen and confirm the opinions I have expressed in each of the three preceding papers on the same question, as to the manner in which the flame cf an explosion is originated and propagated in a dry and dusty mine. The experiments described in the first paper seemed to show that a mixture of air and coal-dust is not inflammable at ordinary pressure and temperature without the presence of a small proportion of fire- damp; but those described in this place show conclusively, I think, that fire-damp is altogether unnecessary, when the scale on which the experiments are made is large enough, and when the fineness and dry- ness of the dust are unquestionable. It may be objected that, although the particular kind of dust I have generally employed may form an explosive mixture with pure air, it does not follow that other kinds of coal-dust will do the same, even under the very same con- ditions as to fineness and dryness.. I am inclined to think, however, that the objection has very little real'importance as far as the general question of colliery explosions is concerned. Possibly the dust pro- duced in mines in which very dry or anthracitic qualities of coal are worked might not behave in the manner indicated. But the number of mines of this class now being worked in this country is far too small, as compared with the whole, to be of any practical account. I may add, in concluding, that the views advocated in these papers, or similar ones, have been held for many years by a few eminent French engineers, including MM. Verpilleux, Vital, and others; and they now appear to be making rapid progress amongst the practical mining men of our own country, who, judging by the reports that have reached me from many sides, are urgently desirous of obtaining as much information on the subject as they possibly can. Kee, 4AG Mr, A. Fraser. On the Development of the [Mar. 30, March 30, 1882. THE PRESIDENT (followed by THE TREASURER) in the Chair. The Right Hon. Anthony John Mundella was admitted into the Society. The Presents received were laid on the table, and thanks ordered for them. The following Papers were read :— I. “On the Development of the Ossicula Auditus in the Higher Mammalia.” By ALEXANDER FRASER, M.B., &c., Senior Demonstrator of Anatomy, the Owens College, Manchester. Communicated by Dr. ALLEN THOMSON, F.R.S. Received March 16, 1882. | (Abstract.) The paper begins by a ‘history of the various views held up to the present date concerning the origin of the Ossicula Auditus. The author then describes the methods of preparation, and the results of his own observations made upon complete series of sections from the rat, pig, sheep, dog, rabbit, calf, mouse, and human embryos at different developmental stages. He givesashort anatomical sketch of the parts in connexion with the proximal extremities of the first two post-oral cartilages, including the ganglion, the maxillary and mandibular branches of the fifth nerve, the seventh nerve, and its mandibular (chorda tympani) branch (noting the relation which this branch bears to the hyoidean cartilage, and the long crus of the incus), the auditory vesicle and its capsule with the difference in development between the oval and round fenestre, the primitive jugular vein, the hyo-mandibular cleft (and its non-perforation in the region of the membrana tympani), and the tympanic annulus. The author describes the malleus as having its origin in the proximal extremity of the mandibular cartilage, the apex of which, growing in a ventral direction, depresses the dorsal wall of the meatus auditorius externus upon the ventral, and thus becomes the manubrium of the malleus. He further compares the embryonic ossicula with their form in the adult, and traces the origin from the mandibular cartilage of certain parts in the adult malleus of Mammalia of great morphological significance. 1882. | Ge Auditus in the Higher Mammalia. AAT He has ascertained that the head of the imcus is the proximal extremity of the hyoidean cartilage, the long crus forming the con- nectmg part between it and the remainder of the cartilage. The short crus is a later growth backwards from the head of the incus. This ossicle agrees in its histological characters with the hyoidean cartilage and not with the mandibular. The mandibular branch of the seventh nerve bears also the same relation to its long crus in the human embryos as it bears to the hyoidean cartilage. The orbicular apophysis is shown to be a part of the long crus, which turns inwards to accommodate itself to the stapes at right angles to its former direction; its constricted pedicle is not formed until after birth. The cells of the embryonic stapes appear contemporaneously with those forming the embryonic cartilage in the arches, or those forming the periotic capsule; they are arranged in a circular form round an artery, which may either disappear very early, as in the human em- bryo, or persist through life, asin the rat. In the former case it is called arteria stapedialis, in the latter arteria stapedio-maxillaris. This circular ring is at first of equal thickness all round, and is not even in contact with the periotic capsule, but is more closely connected with the hyoidean cartilage, although its cells cannot be described as con- tinuous with the cells of that cartilage, their long axes having a circular and not an antero-posterior direction. Owing chiefly to the growth of the cochlear part of the labyrinth, the stapes applies itself to the wall of that cavity, forms a depression there, the future fenestra ovalis; the margins of its base and the head are the last to develop. The articulation between the head of the stapes and the long crus of the incus is formed at the same time as that between the malleus and incus. The tubercle on its posterior crus bears the same relation to the stapedius muscle as the processus muscularis of Hyrtl to the tensor tympani. The stapedius muscle agrees in its develop- ment with the tensor tympani, or any other muscle in the region of the head, and the nucleus in its tendon, which has been described as an inter-hyal, has no connexion with the hyoidean cartilage, in truth, not being present at all in any of the embryos on which I have worked; so that when it is present it must be looked upon as a development in a tendon similar to that which occurs in many other muscles of the body. The author was anticipated by Salensky in the publication of the discovery of the peculiar mode of origin of the stapes round an artery; but his observation of this fact was made independently of Salensky’s, and before the appearance of that writer’s memoir, and he has been able both to correct and to add considerably to Salensky’s description of the development of this ossicle. 448 Prof. A. Wurtz. : [ Mar. 30, II. “ Description of the Fossil Tusk of an extinct Proboscidian Mammal (Notelephas australis, Ow.), from Queensland, Australia.” By Professor OWEN, C.B., F.R.S., &c. Received March 21, 1882. (Abstract.) The author, after referring to the notice of the finding of a molar tooth of a mastodon, in Australia, by Count Strzelecki, in his ‘“‘ Physical Description of New South Wales,” p. 312, proceeds to the details of the first evidence of a proboscidian mammal which has reached him from that continent since the date (1845) of the Count’s work. This evidence consists of portions of a tusk indicative of an elephantine animal, somewhat less than the existing ones of Asia and Africa. The evidences of the ivory nature of the tusk are given in detail, including the minute characters of that variety of dentine. Figures of the fossil and of the microscopical sections accompany the paper. The specimen was discovered by Mr. Fred. N. Isaac, in a “ drift- deposit of a ravine in a district of Darling Downs, sixty miles to the eastward of Moreton Bay, Queensland, Australia.” Ill. “ Action of Ethylene Chlorhydrin upon the Bases of the Pyridine Series and on Quinoline.” By Professor ADOLPH Wurtz, For. Mem. R.S. Received March 17, 1882. According to the constitution which is generally attributed to the bases of the pyridine series, they must be considered as tertiary bases, their nitrogen being united to the carbon by three atomicities. The action which alcoholic iodides exert upon these bases, as shown by Hofmann, confirms this idea, which is equally applicable to quinoline. I thought that the reaction of glycol chlorhydrin and similar compounds upon the pyridine bases and upon quinoline should produce oxygenated quaternary bases. It is known, in fact, that such a base, neurine, results from the action of ethylene chlorhydrin upon trimethylamine. The beautiful results which Ladenburg obtained recently by the reaction cf chlorhydrin upon secondary bases are well known. He is still continuing these researches to the great profit of science. I myself, entering again on a line of researches which I had formally traced, will describe the results obtained by in- vestigations undertaken in the direction indicated, with the pyridine bases and quinoline. I had two specimens of collidine at my disposal, presenting the 1882. ] Action of Kthylene Chlorhydrin, Se. 449 same boiling-point. One obtained by the distillation of aldol-ammonia was undoubtedly identical with aldehydine of Baeyer and Ador (boiling-point 179—182° C.), the other was isolated from the pyridine bases formed by the distillation of cinchonine with hydrate of potas- sium; this collidine is the a-collidine (boiling-point 179—183°).* The experiments have proved that these two collidines are isomeric. Action of Ethylene Chlorhydrin wpon Aldehydine. A mixture of these two compounds, in proportion of their molecular weights, to which a quantity of water weighing as much as the alde- hydine employed was added, was heated during several days in closed tubes to 100° C. The oily layer which floated on the mixture at the end of the operation, continually decreased and finally disappeared after cooling. The aqueous liquid, which was slightly brown, was ex- tracted with ether, and finally evaporated in the vacuum. ‘The ether had dissolved a small quantity of unattacked aldehydine and chlorhy- drin. The chlorohydrate, concentrated by evaporation, was mixed with an excess of platinum chloride, and alcohol was added to the mixture. An abundant crystalline precipitate was obtained, and was purified by several crystallisations in hot water. In this manner magnificent voluminous orange-red crystals of chloroplatinate of oxethyle-aldehydine were obtained. ‘Their analyses furnished the following numbers :— Experiment. — Theory. iif Il. 1 Gt. @arbon,....-... BUD yada BPS. o 528) SILOS eas Wats ydregen ...... NAO Wisi ALA tye AOD 5. vey AOL Nitrogen. ...... Atal eee AOD ue, mu natce Ee Wri VAzy Chilorine../..... DO oar tt. RE he. f, 28°70 Platinum, ....'. Ors Ona: Mo Loh she SOOM Uaenete GOOF On The Analysis III, which is the most accurate, was executed with a salt which had been dried in the vacuum; when this salt is heated to 100° ©. it loses hydrochloric acid, which tends to augment the pro- portion of carbon and of platinum. The Specimen III, after having been heated to 100° during some time, contains 28°2 per cent. of platinum. This alteration, which is more marked in the case of the chloroplatinate of oxethyl-collidine, will be examined later on. The results of these analyses lead to the formula (C,)H,,NOC1),PtCl,, which is that of a chloroplatinate of oxethyl-aldehydine— V | OaN< ort Pcl, * The @-collidine which Mr. Oechsner de Coninck found amongst the cinchonine bases boils at 198°. 450 Prof. A. Wurtz. [ Mar. 30, ' This chloroplatinate forms magnificent orange-red crystals of clinorhombic aspect. It is quite soluble in hot water, and the con- centrated boiling solution, when it cools, becomes cloudy, by depositing oily drops which finally transform themselves into crystals. Decom- posed in aqueous solutions by sulphuretted hydrogen, it furnishes a chloride whose solution is colourless, and does not crystallise after being evaporated during several days in the vacuum. Decomposed by oxide of silver and water it furnishes a caustic soluble base, which attracts the carbonic acid of the air. These reactions permit no doubt as the character of the new base, which is a sort of aldehydine neurine. Action of the Ethylene Chlorhydrin upon a-Collidine. In order to obtain the «-collidine quaternary base corresponding to neurine the method just indicated was employed. The reaction is, however, more rapid than in the previous case; and after heating for a few hours the oily layer disappears, excepting a few black drops which still float on the liquid. The liquid on being extracted with ether, evaporated in the vacuum, and finaliy treated by platinum chloride, furnishes a crystalline orange-yellow precipitate less soluble in water, and much less stable than the preceding one. The analyses of this salt, dried over sulphuric acid, gave the following results ;— Experiment. = $$ Theory. 1 is 1s Carbom'sicisracyotit Sas Scale te a 723, Ete dicO SOM errs aesens zi Omer ars le wee aie led bimnote sony’. 3 Wi ae 26°32 .... 2616 Jo 3eeeeoere The solution of this salt in hot water becomes of a deeper brown-red colour the more concentrated it becomes. On boiling it decomposes. Its solution in a large quantity of hot water, on cooling deposits orange-red crystals tinged with brown. ‘These crystals give the following numbers when analysed :— Experiment. | aT Theory. If nk Orange crystals from the mother-liquor. Carbonfnvaatan: 30°39 .arh oc. » oo xe GSIES Cee Hydrogen. 52%). Ar Q9weane sty iba .csar 4ghe ix, Seen Plitmumy.... 2. OT AS. 202. 27:02... 0260-33 ee one These crystals do not possess exactly the composition of the chloroplatinate, (C,)H,,NOC1),PtCl,, which must therefore be altered by the action of boiling water. In fact, the solution became deeply } 1882.] Action of Ethylene Chlorhydrin, &c. 451 coloured after several minutes’ boiling,* and on being decomposed by sulphuretted hydrogen, furnished a solution which, after being evapo- rated on the water-bath and filtered, showed a brown tint, and gave after several days brownish-red crystals. These were purified by crystallisation from boiling alcohol, in which they are very slightly soluble. By the cooling of the solution a salt was obtained, which erystallises in brilliant scales, possessing a brownish tint, and corre- sponding exactly to the formula of a chloroplatinite of oxethyl-a- collidine, C,,H,;(PtCl)NOCL. Theory ( JAITE| 00) 1s ere are Soros ahs ge: 30°84 EMV ALOE s/s 6 <0. tyo: CEG enn 442, Whlowine rs 2 22 ss. 20280" sacle. 21°30 PBN halo 0 10a ne SU Ee oD Oe 29°42 This salt is derived from the chloroplatinate of oxethyl-«-collidine by loss of hydrochloric acid :— (C,,H,,.NOC1),PtCl,=2HCl+ (C,,H,,NOC1).PtCl,. The crude chloride of oxethyl-«-collidine, or the chloride separated from the unaltered chloroplatinate by sulphuretted hydrogen, treated with chloride of gold, furnishes an abundant precipitate, which con- denses directly into dark yellow drops.+ These drops soon transform themselves into crystals, which melt under hot water, but are soluble in a large quantity of boiling water. The solution, when cooled, deposits first yellow drops, then magnificent thin needles of golden- yellow colour. They are the chloroaurate of oxethyl-«-collidine, Ci) H,,NOC1.AuCls. Theory WHEDON vance aw Ye se 3 ZH diag, slits saa 23°79 LE Ly dhdosede are ee ED) pisisyee oy: aalkg INAGKOGOM) 3 <4 sna. : ey aE heen: Plame $5 Ole a2 o< lst Gens SOO Ole disses duces 38°91 Action of Ethylene Chlorhydrin wpon Quinoline. The quinoline which was employed in this experiment was obtained by distilling cinchonine with hydrate of potassium, and possessed, after a great number of rectifications, the boiling-point 238—240° C. The quinoline was heated with an equivalent guantity{ of glycol chlorhydrin, to which its weight of water had been added. After * In one experiment an elimination of a small quantity of platinum which blackened the liquid was noticed. + With the crude chloride a dark coloration, due to a reduction of the gold salt by some impurity, is observed. { 16 grs. of quinoline for 10 grs. of chlorhydrin. 452 Action of Ethylene Chlorhydrin, &c. [| Mar. 30, three days’ heating, the oily layer had entirely disappeared. The mixture was cooled and extracted with ether, and the aqueous solution, slightly coloured brown, was concentrated. After a few days, the solution contained a great amount of brown crystals, which were strongly pressed between layers of paper, and finally dissolved in absolute alcohcl. The solution was treated with animal charcoal, filtered boiling, and, after cooling, anhydrous ether was added, so as to float on the alcoholic layer. The next day the alcoholic solution was filled with magnificent colourless prisms, some of which traversed the entire vessel. This salt is a chloride of oxethyl quinoline, CyHyNOCI=C,HN< Ces, formed by the addition of glycol chlorhydrin to quinoline. Theory. Carbone see 63°20 ;ee ee mere | (Ora Eiydropent: .. 02090 Rie Ae ay Nitrogen..... OrSBve ieee bd GES Chilonme= =.=, 16:29) Lore “OLD eae This chlorhydrate has a bitter taste, attracts the atmospheric mois- ture, and is very soluble in water and in alcohol, insoluble in ether. Its aqueous solution is not precipitated by ammonia, and gives with potassa a thick, coloured precipitate. Boiled for several seconds with oxide of silver, the solution forms chloride of silver and reduced silver, and the filtered liquid possesses a very strong alkaline reaction, and rapidly assumes a crimson tint. The hydrate of plumbic oxide decom- poses this chloride in a similar manner. Corrosive sublimate forms with it a compound which crystallises easily. Chloride of gold produces, in the solution of this chloride, a yellow precipitate, soluble in boiling water, from which it erystallises on cooling in small crystals, which appear under the microscope as pointed lozenges. This chloroaurate possesses the formula C,,H,.NOC1,AuCl,. | Theory Carbone) iit, enw 26' 2s See 25°77 Hydrogentue leaps # 2 OA: 1) ae 2°34 Goldact uk Rie 87-983. See 38°30 Platinum chloride forms a chamois-yellow precipitate in the solution boiling water, and crystallises from the cold solution in small opaque | orange crystals of the formula (C,,H,,NOC1),PtCl,. i f if of the chloride. This precipitate is soluble in a large quantity of | | 1882.] On the Movement of Gas in “ Vacuum Discharges.” 458 Experiment. -— —~- ~ Theory. I. If. III. Warnome ....... SVs te OAOA W445 Go OO umes Oa oe Elydvogen ...... Sia ies SOO ee eae Toro aes SOLO INGoreg@en ....... TAU eeesent Malena Wsabetetalntiuicbs. baal dl Mikes 7A Wmlorime.:...... ii eee i a acai gales ae CSAC) EIU... .. . ZOOS.) LOLS) so CAO) ata 70:0 The Specimen I was the pulverulent yellowish chloroplatinate, simply precipitated and dried inthe vacuum. The others had been dis- solved in boiling water, and were thereby slightly altered, as the ex- cess of platinum proves. When quinoline is heated with an equivalent quantity of ethylene chlorhydrine without adding water, a dark purple- reddish mass is obtained. Extracted with ether, dried and treated with absolute alcohol, this mass gives a dark violet solution, which, if ether is poured on it, deposits an almost black mass, which finally erystallises. The crystals, pressed between sheets of paper, are sensibly less coloured than the mother-liquor, which imparts to the paper a dark violet colour. I have not yet concluded the analysis of this product, and I propose to continue these researches in various directions. IV. “On the Movement of Gas in ‘ Vacuum Discharges.” By WILLIAM SPOTTISWOODE, P.R.S., and J. FLETCHER MovuLtTon, F.R.S. Received March 25, 1882. In the preparation of tubes for our experiments it was often noticed that, after the exhaustion had been carried to a certain degree, the passage of a strong current had the effect of increasing the pressure. This appeared to be due to an expulsion of gas from the terminals themselves by the passage of the discharge. And accordingly the use of such currents from time to time during the process of exhaustion was adopted for making the vacuum more perfect and more permanent than otherwise would have been the case. On the other hand, it was also noticed, that after the tube had been taken off the pump and sealed in the usual way, the passage of a strong current had in some instances the effect of decreasing the pressure. We thus met with two effects, apparently due to the same cause, but diametrically opposite in character. The fact of the tube being on the pump or off it did not appear to be at all material to the question, because the first effect could be obtained when the tube was temporarily shut off by a stopcock. Nor indeed did either the first or the second effect depend upon the absolute 454. The Movement of Gas in “ Vacuum Discharges.” [Mar. 30, | pressure, although neither was observed except when the pressure was such as to approach the stage when Crookes’ phosphorescence was produced. These phenomena also reproduced themselves in another way. Some tubes, after having been completed and taken off the pump, showed a decreased pressure after a prolonged passage of a strong current, others an increased pressure, but among beth classes tubes were not unfrequently found which recovered their original pressure after a period of rest or cessation of discharge. Matters remained in this rather confused state until we observed with more care than before a tube of which the exhaustion was near the phesphorescent state, and of which both terminals were metallic cones, and consequently presented large surfaces for any action which might take place upon them. In what may be considered to have been its normal condition, this tube showed three or four large white striz with a dark space of con- siderable size round the negative terminal. On passing the discharge through the tube for some minutes the dark space increased, the striee became fewer and feebler in illumination, the green phosphores- cence began to show itself, and the discharge showed the usual signs of reduced pressure. On suddenly reversing the current the strize became again more numerous and more brightly illuminated, precisely as they would be by an increase of pressure, while the other features of the discharge in a great measure resumed their original character ; and not only so, but by a comparatively slow process, occupying many seconds in duration, the indications of increasing pressure continued still further, until they implied a pressure even beyond that at which the tube stood when the experiments began, after which the appear- ance slowly changed as before in a manner indicating reduced pressure. ‘This reversal of the discharge was repeated many times with the same result in every case. The amount of change in pressure indicated by the appearance on each reversal was found to depend within wide limits upon the duration of the previous discharge, or, what is the same thing, upon the amount of depression below the normal pressure indicated by the previous discharge. The most probable explanation of these phenomena appears to be this, that the effect of the discharge is actually to alter the pressure in the tube, not by any modification in the chemical composition of the gas, still less by anything that could be represented as a destruction of matter, but simply by driving occluded gas out of one terminal, and by drawing it in, or occluding it, at the other. On reversing the discharge, the operation is reversed, and the occluded contents of one terminal are thrown along the tube to be occluded at the other. This view of the mechanism whereby the observed phenomena are produced is supported by the absence of these appearances when the terminals are compara- 1882. ] Presents. 455 tively small and the pressure is such that the occluded contents of the metallic mass forming one terminal would form only a small fraction of the total mass of gas in the tube; for in that case the pressure, and consequently the appearance of the discharge, would be affected only in an inappreciable degree by the injection of the contents of the ter- minal. It should also be added that, when the terminals are of unequal size, the effects are unequal, as might have been expected. The phenomenon in question appears to have so important a bearing on the mechanism of the discharge itself, that it becomes a question of ereat interest to determine whether the missing gas is to be found in either of the terminals ; and if so, whether the ejection takes place at the positive, and the occlusion at the negative, terminal, or vice versdé. For this purpose I have devised a tube with three terminals, but have not yet had time to complete its construction or to make the experiment. Presents, March 2, 1882. Transactions. Hastbourne :—Natural History Society. Transactions. New Series. Vol. I. Part 1. 8vo. Hastbourne 1881. The Society. Erlangen :—Physikalisch-medicinische Societaét. Sitzungsberichte. Heft 13. 8vo. Hrlangen 1881. The Society. Munich :—K. B. Akademie der Wissenschaften. Sitzungsberichte. Math.-Phys. 1882, Heft 1. Phil.-Hist. 1881, Bd. II. Heft 3. 8vo. Miinchen 1881-2. The Academy. Newcastle-upon-Tyne :—Chemical Society. Transactions. Vol. V. Part 7. 8vo. The Society. Public Libraries Committee. Report, 1880-81. 8vo. Newcastle- upon- Tyne. The Committee. New York :—American Geographical Society. Journal. Vols. XI, XII. 8vo. New York 1879-80. Bulletin. 1881. No. 2. 8vo. . New York 1881. The Society. Prague :—K. Bohmische Gesellschaft der Wissenschaften. Abhand- lungen. Folge 6. Band X. 4to. Prag 1881. Sitzungsberichte. 1879, 1880. 8vo. Prag 1880-81. Jahresbericht. 1879, 1880. 8vo. Prag 1879-80. Joseph Emler; Decem Registra Censuum Bohemica. 8vo. V. Praze 1881. The Society. Rome :—R. Accademia dei Lincei. Transunti. Vol. VI. Fase. 5. Ato. Roma 1882. The Academy. St. Petersburg :—Académie Impériale des Sciences. Mémoires. Tome XXIX. No. 2. 4to. St. Pétersbourg 1881. The Academy. Tokio :—University. Memoirs of the Science Department. Nos. 4, 5. 4to. Tokio 2541 (1881). Calendar. 2540-41 (1880-81). 8vo. Tokio 2540 (1880). The University, per the Japanese Embassy. 456 Presents. [Mar. 2, Transactions (continued). / Yokohama :—] Manis Meyer (Adolf Bernhard) Verzeichniss der Schriften von A. B. M. 1867-81. 8vo. The Author. Packard (A. 8.), Junr. Excerpts from the ‘‘ American Naturalist.” Svo. The Author. Pickering (H. C.) Excerpts from ‘“ Astronomische Nachrichten ” and ‘‘ Proceedings of the American Academy.” 1881. _ The Author. Plantamour (P.) Des Mouvements Périodiques du Sol accusés par des Niveaux 4 Bulle d’Air. 8vo. Geneve 1881. The Author. Plateau (F.) Préparation Rapide des Grandes Pieces Myologiques. 8vo. Paris 1880. The Author. Plateau (J.) Une Application des Images Accidentelles (2me Note). Svo. The Author. Riitimeyer (L.) Beitriige zu einer Naturlichen Geschichte der Hirsche. Theil I. 4to. Zirich 1880-81. The Author. Presents, March 23, 1882. Transactions. Calcutta :—Geological Survey of India. Records. Vol. XV. Part. 1. Svo. Calcutta 1882. The Survey. Newcastle-upon-Tyne :—Chemical Society. Transactions. Vol. V. Part 8. 8vo. The Society. Rome :—R. Accademia dei Lincei. Transunti. Serie 3a. Vol. VI. Fasc. 7. 4to. Roma 1882. The Academy. Sydney :—Linnean Society of N.S. Wales. Proceedings. Vol. VI. Part 3. 8vo. Sydney 1881. The Society. Journals. American Journal of Philology. Vol. II. No. 8. 8vo. Baltimore Iteren The Johns Hopkins University. Bulletino di Bibliografia e di Storia. Tomo XJV. Gennaio—Aprile, 1881. 4to. Roma 1881. The Prince Boncompaeni. Canadian Antiquarian. Vol. VI. Nos. 3, 4. 8vo. Montreal 1878. Major Huguet-Latour. New York Medical Journal. Vol. XXXV. Nos. 2, 3. 8vo. New York 1882. The Editor. Bonney (T. G.), F-R.S. A Chapter in the Life History of an Old University. 8vo. Cambridge 1882. The Author. — Cauchy (Augustin) (Euvres completes. Ire Série. Tome I. 4to. Paris 1882. L’ Académie des Sciences. | 1882.] Presents. 461 Clifford (W. K.), F.R.S. Mathematical Fragments: being Facsimiles of his Unfinished Papers relating to the Theory of Graphs. Small folio. London 1881. Messrs. Macmillan & Co. Liversidge (A.) Table for Qualitative Chemical Analysis. 8vo. Sydney 1881. The Author. Plateau (J.) Quelques Expériences sur les Lames Liquides Minces. Svo. Bruzelles 1881. The Author. Seacchi (A.) Notizie preliminari intorno ai proietti vulcanici del tufo di Nocera e di Sarno. 4to. [Roma 1881.] Sul Legno Car- bonizzato del Tufo di Lanzara. 4to. [Napoli 1881.] Notizia delle Fenditure Apertesi nella Pianura di Aversa nell’ autumno del 1852, &e. 4to. [Napoli 1881. ] The Author. Sihleanu (Stefan St.) Principii de Zoologia Generale relative la Anatomia si la Fisiologia Animalelor. Tomul I. Partea Generali. S8vo. Bucuresci 1881. The Author. Sturm (Rudolf) Ueber die reciproke und mit ihr zusammenhang- ende Verwandtschaften. 8vo. Minster 1. W. 1881. On some New Theorems on Curves of double Curvature. 8vo. London [ 1881. ] The Authox. Presents, March 30, 1882. Transactions. Geneva :—Société de Physique. Mémoires. Tome XXVII. Partie 2. Ato. Geneve 1881. The Society. London :-—-Mathematical Society. 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Synopsis of Results. Vol. X-XIIT. 4to. Dehra Dun 1880. The Survey. London :—Meteorological Council. Report to the Royal Society. 8vo. London 1882. The Meteorological Office. Bevan (G. Phillips) The Statistical Atlas. Parts 6-15. folio. London 1881-2. The Publishers. Gore (G.), F.R.S. The Scientific Basis of National Progress, including that of Morality. 8vo. London 1882. On the Hlectro- lysis of Sulphate of Copper. 8vo. Birmingham. The Author. Holden (Edward 8.) Studies in Central American Picture-writing. 8vo. Washington 1881. The Author. Johnson (Rev. 8. J.) Projections of Hclipses of the Sun and Moon. A.D. 1882—-a.p. 2000, &c. MS. The Author. Pole (William), F.R.S. A Study of the Problem of Aerial Naviga- tion, as affected by recent Mechanical Improvements. 8vo. London 1882. The Author. Tenison-Woods (Rev. J. H.) Thirty-two Hxcerpts from ‘‘ Proc. Royal and Linnean Socs., N. 8S. Wales,” ‘Trans. Phil. Soe. Adelaide,” ‘‘ Proc. Royal Soc. Tasmania,” &c. The Author. “The Effects of certain modifying Influences on the Latent Period of Muscle Contraction.” By GERALD F. Yxo, M.D., F.R.C.S., and THEODORE CasH, M.D. Communicated by Dr. SANDERSON, F.R.S. Recerved June 15. Read June 16, 1881. Although the labour of many physiologists has been directed to- wards the consideration of Latency, it seemed:to us desirable that the — subject should receive a little addition in some of its details, and it was with the object of thus filling up deficiencies, and at the same _ time of studying systematically the effect of some of the agents which — modify the time of latency, that we undertook the investigations, the | results of which we desire to lay before the Society. In 1867 Helmholtz and Baxt* published the results of experiments they had instituted touching the speed of conduction in motor nerves : as measured by the relative latencies obtained in a nearer and more ' distant stimulation of a nerve-trunk (frog) or of the skin above it, | and in publishing their experiments of 1870 they drew attention “| the modifying influence of temperature upon such conduction. Thus || * “ Monatsbericht d. Berliner Acad.,” 1867, s. 228, and 1870, s. 184. : | On the Latent Feriod of Muscle Contraction. AG3 they saw the speed decreased to a great extent when the nerve was laid upon ice, and even slight variations in the room temperature sufficed to produce material changes. Troitzky* came to the conclu- sion that conduction is the most rapid in the frog’s nerve between 10° and 20° C., and diminishes both by higher and lower temperatures. The influence of temperature could, however, he concluded, be subor- dinated to a ‘certain extent by increasing the strength of the stimulation. That a powerful shock is more potent to induce rapid conduction than a weaker one has been upheld by Valentint and von Wittich as well as by Troitzky, but has been denied by Rosenthal{ and Lautenbach.§ These interesting results would have been still more valuable had accurate corrections been made for the variations in the rapidity of the initial changes taking place in the muscle itself during the latent period, for, as Hermann suggests, changes in the strength of the stimulus may cause these variations to be con- siderable. An instrument, designed by du Bois Reymond — the ‘‘ Frosch- Unterbrecher ’—has made the fact apparent that the period of latent energy elapsing between stimulation and obvious contraction also increases if increasing weights, acting as ‘“‘after-weights,” be laid in the supported pan suspended from the muscle. Thus, whilst at lever- tension—at which point the support was fixed—the latency may be less than --35 second, under a weight of 200 grms. it may be more than twice as much. It is evident that whether the muscle be ‘“ free- weighted” or “after-weighted,” until it has reached a state of counterbalancing tension as regards the weight it is to raise, no ele- vation from the abscissa can be effected. The free-weighted muscle is already stretched as regards the greater number of its fibres by a small weight (30—40 grms. for gastrocnemius of frog), whilst the, after-weighted has to attain a similar state of tension before it can commence its true lift. Variations in latency are then to be expected according to the connexion in which we place the weight and the muscle. Place|| and Klunder remark that if, after a muscle has been powerfully extended, and while it is returning, by reason of its elasticity, towards its normal condition, a stimulation be appled, the latency may become as short as the 53,—z}, second, a result which Haidenhain** inclines to attribute to the pernicious effects of the previous tension. * “ Arch. fir d. ges. Physiologie,” viii, s. 599, 1874. + Moleschott, ‘ Untersuchungen,” x, s. 526, 1866. t “ Monatsbericht d. Berliner Acad.,” s. 419, 1875. § “ Archiv. d. Science Phys. et Nat.,”’ Juli, 1877. || “Handbuch der Physiologie,” Bd. 2, p. 24. €{ “Nederlandsch Arch. vy. Genees en Naturk.,” iti, p. 177, 1867. ** “ Untersuchungen aus dem Kieler Institut,’ p. 101, 1868. 464 Drs. G. F. Yeo and T. Cash. The instrument which served us for registration of the contraction was a modification of Fick’s pendulum myograph, manufactured by the Cambridge Scientific Instrument Company. It was provided with an extensive arc, having movable catch adjustments, so that the velocity of the recording surface could be readily modified. The primary current was broken by the arm of the swinging pendulum, and if occasion required a second contact, the relation of which to its neighbour could be regulated by a micrometer screw, could be em- ployed in conjunction. The recording plate could be elevated so as to register a series of some 30—40 curves, one over the other. The moist chamber, containing the muscle, &c., was placed on a table which could be withdrawn or advanced to meet the plate (acting like the slide-rest of a lathe) without altering the relationship of the writing point to the recording surface. Within the moist chamber, and sur- rounding the muscle, passed several coils of metal tubing, which could be heated or cooled at pleasure by passing heated or iced water through it from a system of tubes terminating above in double funnels. The temperature was accurately measured by a Centigrade thermo- meter placed in the moist chamber, its bulb being equidistant from the muscle and the tubing. The lever, designed by one of us, was made of two straws separated to the extent of 14 inch at their union with: the axis, and converging at the other end to a pointed strip of pla- tinum foil, which acted as a pen. The weight of this lever, witnout the friction of the pen, was about 1 grm. The weight was suspended round the axis of rotation, except in those cases in which it appeared desirable to apply it in the line of traction of the muscle. Great steadiness, absence of appreciable friction, and elimination of the effect of the “throw up” sustained by a lever weighted anywhere except at its axis, were ensured by this adjustment, and the great lightness of the lever arm. In view of the fact that the nerve is more rapidly influenced by those agents which we proposed to employ in modifying the manifes- tations of latency, and also because we desired to look chiefly to the actual effect such agents produced on the changes necessary to the subsequent contraction, rather than to the varying conductivities of the nerve, we chose the curarised muscles (the gastrocnemius of the frog) for the bulk of our experiments. We may mention in this place that we found the variations between the non-curarised and curarised muscles, both stimulated directly and at room temperature (17—18° C.), so slight that they may be disregarded. Maximal stimulation was employed in all cases, except where other- wise specified. Our experiments were performed on ana temp., between the 10th January and the middle of April. Though we have thought well to give frequently the measurement of a series of curves taken from a single muscle, we have done this On the Latent Period of Muscle Contraction. 465 only in order to show a sample selected from a large number of curves, and presenting in a fair degree the peculiarities which custom has taught us to expect from the circumstances of the case. The first experiments were directed to contrasting the latencies of contractions obtained by stimulating nerve or muscle. The length of nerve attached to the preparation which yielded the following measurements was 12°5 millims. The weighting of the muscle was free, and the weights which were suspended sufficiently long before stimulation to cause a proportionate extension increased from lever weight, z.e., 1 grm., up to 100 grms. The duration of the latency and of the contraction is expressed in figures indicating the number of double vibrations of the tuning fork used to record the time. Hach D.Y. corresponds to ;3, of a second, which fraction of time therefore forms the unit in the following tables. The altitude of the curve is given in millimetres. Table I.—Stimulation of Gastrocnemius Indirect and Direct. . Length of | Length No. Weight. [AUER amas | aeeee 7 a in mm. in 180 : in 130 : Muscle... 22 i 2 24 °8 25-0 Nerve..... 21 ie ag { 2°75 23°75 24°5 MES i. 20 10 2°20 22 °6 22 °3 ices 19 I ei { 3-05 21-5 22-0 ME 18 } 20 2°35 22 °0 21°0 pene: 17 ” { 3 +10 21°3 21°3 den 16 i 30 2-4 21°75 19°5 | ee 15 ” { 3-25 21-0 20-0 M.. 14 i 40 { 2°55 21°5 18-0 Ns 13 ad 3° 4: 21°5 18°0 LAE 12 \ 50 2°6 21° 16°5 Ret os. 3. 11 ” { 3°45 20°5 17-0 Wie yt. 10 60 2°60 21°5 15°2 AN, 9 } 22 { 3°5 20°7 15 °2 M.. 8 “0 2°75 21°75 14.°4 2 ae vi \ ‘ ” 4 By aS: 20°5 14.°4 M.. 6 80 3 °0d 22-0 14°2 eee ee 5 } ze { 3°65 21°35 14-2 Joes eee fb \ 90 J 3°12 22-0 14°53 N.. 3 ew leat eds 21:9 14-0 ME. 2 PSacp a fae tee | we | ise | 3-2 22-738 13°53 N.. 1 ” + 4-0 22 -0 13°5 The fact that the increase of PR okco ot waikhta dadass on tnotonbo’ob ine causes an increase of latency will be at once appreciated after an examination of the table. The latency of contraction under lever weight when the stimulation is direct is ‘011i’, and when indirect -0152”. Under 50 grms., direct 0144”, indirect :0191’’; and under 100 grms., direct :0177", indirect 0222”. AG6 Drs? G. Hy Yeo-und E.:@arh: Striking a mean between the light and heavy weight we should obtain the figures—for the direct -0144", and for the indirect ‘0187, both of which approximate closely to the experimental measurements of the middle weight. If we tabulate, for increasing weights, the actual increase of the latencies, so that the prolongation for each increment may be readily wl recognised, we find in ;3,° :— Weight increase. Latency increase. Muscle. Nerve. NO korena sae es tear Oy i age ci Race “30 7A AR ae ANE Soh UC Re a 05 OO cia enue ag LOS pe eee 15 AS ot aie inert MO Se. ouaeeevseauee "ls OO ess peed ase eae (0): cy 1 ae ee 05 OO ce © rote. rises 5 OS emieastcrensts 6 Ati 05 (Og Baia eee “Ouch Meeereee ‘05 S00 ee 3) ho ee 10 Oe rie. woken Seen FOW = ato eacton tees 0) HOO) Se sinsewsae ae (OS aide coke Se "25 1°20 1:25 The greatest difference appears to obtain at the extremes of the scale, z.e., when the weight is first applied, and when it is beginning to be too severe for the muscle, whilst in the middle part of the series the variations are slighter and more uniform in character. If we glance at the other two columns in Table I, we see that this middle part contains the shortest curves exhibiting altitudes midway between those of the extremes. The fact established by Marey,* that a muscle hindered by the weight applied to it from reaching its maximum of contraction is slower in its relaxation than its less weighted neigh- bour, accounts for the long low curve under 100 grms. As regards the comparison between the muscle stimulated directly and indirectly, we may state from our results, that which previous con- sideration had convinced us must be the case, viz. :— At ordinary room temperature, the increase of latency bears the same proportion to the increase of free burden in direct as in indirect stimulation. 2. It has been alledged that curare increases the latency, and as we desired to use the curarised muscle in certain of our experiments, we made comparative observations with the result of convincing ourselves that as a rule no such prolongation occurs; but that the course of latency of the curarised and of the non-curarised muscle, both stimu- * “ Du Mouvement dans les Fonctions de la Vie,” 1868, p. 363. On the Latent Period of Muscle Contraction. | 467 lated directly, and under varying burdens but constant room temperature, is strictly parallel. Upon the influence which curare may exercise upon the curve of contraction, we cannot enter here. The weight was gradually increased from lever to 100 germs. Table I1.—Contrast between Curarised and Non-Curarised Muscle. Length of latency | Length of curve Altitude in in ;1,”. in +45’. millims. No. Weight. Non-cur.| Cur Non-cur. Cur. | Non-cur.| Cur. 1 and la| Lever | 1°85 1°85 30-0 BOR esis I 2950 Za 2a) 1Ogrms.|, 1-9 1g) 24-5 26 ‘0 20°0 ees eee 20 +.,, 2°02 2) 23-0 20°5 LPS =O As aa. | 30 -,, 2°10 2°05 22°5 20:0 16°5 30 aoe! 40). ,, 2-30 2-25 Zi 75 OES 16:0 WAL as Petes 150... | 2-47 | 2-5 21-25 | 19°6.| 15-0 | 11-0 feed G0! -,, 7) 5) 2°6 21 -20 NO as EO Sage oa | 70 .,; 2°65 2°72 21-25 20-0 13 10°5 Bee Oa) bo) ,, 2-80 2-85 22) 335 Oy i IB as 10-0 he, 10a, | 90 ,, 2°90 2°95 22°5 Pah. 225 9-5 eee ita 00! - ,. 3°00 3°00 22°75 22-0 12:0 g-0 There are slight variations usually in the second place of decimals between the two columns, but if the figures are—as we believe them to be-- trne measurements, we still require more extensive proof of a permanent difference than the occasional variation of a 3,55”. Our result then is that at room temperature, the latency of the eurarised and non-curarised muscles directly stimulated is equal for equal weights. 3. What is the relationship as to latency of the free-weighted muscle tensed in proportion to the weight it carries, to the after-weighted muscle, which has only the same slight initial tension under similar weights? As this question seemed to us to be an interesting one, we made a few observations, so as to obtain a fair contrast between two muscles placed under these widely differing circumstances. The after-weighted muscle was supported, so that the weight of 10 germs. just résted upon the catch, from which the contracting muscle raised it. We give a double column of the resulting differences of the free-weighted and the after-weighted muscles. The influence of the spppcort seems to increase the earlier latencies, and it is in great measure owing to this effect that the variation is so much greater in the case of the after-weighted than of the free- weighted muscle. 468 Drs. G. i Yeo and T. Cash. Table III.—Contrast between Free-weighted and Atter-weighted Muscle. Decrease in Latency. Weight increment. Free-weighted. After-weighted. Lever to 10 grms. .. 0'250f D.V.— 2, .. 045 01D) Olean. 3 tO poe hewte cy RO Oe 4. ae OO) 7 ORR ead 151 bs raids So ia )2(0)5) “3 Se UU a Ca Oa rrernaiess tac 40) agsetrayins rah cu de) QU, +5 sansa) ss AO) aisrriages DO” wemyaieee Cates 5 2 00S _ DO icc OO sek Bea DEO, 55 = 6 WOOD ie OO or ae Oe ORG ‘ >.) O05 Ms; AON sg toh oO) ostler oO: 3 se 0220 _ BOs eh, 90 ire eels, see ..* O05 ean Diels LaLOOr whe tOal@ i von i TCO 1°20 The weight of the lever alone (about 1 grm.) leaves many of the fibres of the gastrocnemius not tensed, and this condition is closely parallel to a mechanical support of a heavier weight. If the weight can be lifted without the co-operation of these fibres, the latency is short, but should the addition of only 10 grms. require the tension of many of them, the latency becomes markedly increased. 'Thus it is that the greatest differences lie towards the commencement of the scale of weight increment of a free-weighted muscle, and thus that the after-weighted muscle shows such greatly prolonged latencies at the same period. We conclude therefore— That the latency of a muscle with supported weight is greater than with unsupported weight, and that the greatest variation between the two occurs under the lighter weights. 4. We have referred at the commencement of this paper to the influence of weight upon latency, and we have shown subsequently - that the addition of 100 grms. causes a marked prolongation of this period. As we desired as far as possible to avoid fatiguing the muscle, we did not carry our weights, as a rule, beyond 100 grms., though a few observations on fresh muscle weighted with 200 grms. were made in order to see in what manner the further weight acted. If we examine the prolongation of the latency caused by increasing the weight gradually from lever weight to 100 grms. we find that there is an average increase of about ‘0063”. In glancing over a number of observations and preparing their aver- ages, we found that the greatest influence exercised by any one weight- difference (of a series of equal increments), was that resulting from the suspension of the first 10 grms. from the lever; this might cause an On the Latent Period of Muscle Contraction. 469 average increase of "1625 D.V. The application of the three succeed- ing 10 grm. weights would have a conjoined effect of *3384_D.V. The middle weights 40—70 grms., as has been already noticed, have less influence in prolonging the latency, their value would be about "284 D.V., whilst the last series of these has again a much larger effect, equal together to ‘354 D.V.; thus the extremes show greater variations amongst themselves than do the constituents of the inter- mediate series. levers to lOerms) 22.1625 DLV.= :0009” WOumiss. 20). ,, AUN OO!” 5, pia ‘SOOA a == OOH 30 Se 40) 9 40) 99. OW 9 BOM, 6000, pee 284 ,, =-00157” Co Ommerrne O! 4) 70 99 80 ” 80 Oe 9) 90 ” cs 354: 9 = J0N9G" 90 ,, ,, 100 ,, , Mota hers PUSS) We feel inclined to hazard a corresponding division on mechanical grounds as follows :— Lever (wt. 1 grm.)=tension of many muscle bundles very incom- plete. 10—40=these bundles brought into action by the added weight. 40—70=all bundles active and unwearied. 70—100=strain of some of bundles, commencing weariness. During the suspension of the second 100 grms. the variation in latency only amounts to about one-half of that which obtains during the first 100 grms. Latency is then prolonged by increasing the weight, but it does not increase in a definite ratio to the increase of such weight. 5. Our attention was next turned to the effect of fatigue upon the muscle in modifying the latency occurring after stimulation. To induce fatigue we delivered to the muscle a certain number of opening induction shocks—maximal intensity—in a given time, or we admitted an interrupted current completely tetanizing the muscle for a specified period. After the muscle had remained at rest for a short interval a curve was taken, and the comparison of the latency of this curve with that taken before the tetanus or induction shocks had been adminis- tered was supposed to represent the effect of the stimulation which had intervened. A weight of 10 grms. only was applied to the lever during these experiments, so that injury from undue tension of the Av0 Drs. G. F. Yeo'and T- Cash. muscle fibres might be avoided. The temperature of the room was drommlid cabo WS4:o: C, In the case of fatiguing by simple induction shocks, 100 stimula- tions were delivered (one every 2’’) from Ludwig’s clock between the registration of every two stimulations. The results showed that whether in the case of the curarised muscle or of the healthy muscle stimulated indirectly, the first 5—700 shocks produced but very shght changes, not amounting frequently in all to an increase of over =; of a double vibration, or °00055”. A curious result occurring occasionally after a few hundred stimu- lations only had been administered was that the latency became actually diminished to a slight extent, namely 00027” to -00044", as if the moderate amount of exertion through which the muscle had passed favoured the more rapid consummation of the changes in the muscle preliminary to contraction. This diminution was followed by a return through the original to a more rapidly increasing latency. The prolongation after 900—1,000 contractions is distinct -00132"’ to 00222”, whilst after 1,300—1,500 a rapid prolongation associated with loss of excitability (as shown by the long shallow curve with greatly retarded relaxation) is seen. The following figures illustrate the course of such a case. Grastroc- nemius, 100 contractions produced after each curve by maximal stimnlations given every 2 seconds. About l’ rest between each set of stimulations. Normal latency 270-50. On 100 stimulations: *..2...8 Si 200 Ah RUE Shan, Aca Re: == ails) 300 fs MRIS eS eG == Jule 4.00 AER ADM OK Pe ETRE =a 500 “1 > Na ia rs et = 22, 700 fi ale oh ae =A 1,000 RMA ELE chile AE = 9°45 1,300 ee aie ie tae = oulle When tetanus was used asa means of fatigue the interrupted current was admitted for 10” to the muscle, and aiter the fibres had relaxed so that the lever had regained the original abscissa the comparison curve was taken. We find that the change occurring in the latency is not altogether dissimilar to that of the muscle stimulated by simple induction shocks, that is to say, that the increase during the first 6—8, 10” stimula- tions is not very great; but that after this point the latency tends to increase rapidly till at the 13th, 15th, 10-second tetanus a much pro- On the Latent Period of Muscle Contraction. AT1 longed latency with an associated low, long curve, showing great viscosity or slowness of extension, is to be observed. It differs in this respect, however, that the lengthening of the latency is already well marked after the muscle has been subjected once or twice to the 10” tetanus. It is not unusual after a lengthening of the latency has occurred for it again to diminish, if not to a point below the original, at any rate to one distinctly below some of its predecessors. This peculiarity does not persist to the point at which the viscosity of the muscle becomes increased and the curve much prolonged, but coexists with a strong contraction followed by complete relaxation, and this point, be it coincidence or not, 1s worthy of note. The following figures show the frequent course of such an experi- ment :— Length of Latency in D.V.=;1,”. 1 2 FRCS I Tae areas er ii RO ie eR RE a0 pactiners WO) fetamMuUss sis. 4. 3 ee Sala ee 20) RE ees Ms, Arh: S20) aes ee U) 5 un Cen base Me eel ite Sion ee A() ee att oan, ie Seale As 3 G0 Bh oaugset easton ll a er Sale 3 60) SSW LAtbla es. Seah AR oF alone 0) sdetails bras ky saan Sea ss ep eilits\@) tdi yt eS cia a a ina re) een ATM Aer ee BO 3 8 MOO) Pamir AU Ns, ays Ar Stn. te op UIKD) sel DIES Se Seale ea AO a OD) Pe aaty Ra arenas. Bice 3 Ar QP i. 120” tetanus administered in the course of about 30’ at regular in- tervals causes a prolongation of ‘00666". Fatigue is more rapidly induced by indirect than by direct stimulation. , Fatigue then increases the latency, at first slowly (500 induction shocks or 60” tetanus), and then more rapidly till the exhaustion of the muscle (1,500 single contractions or 130” tetanus) when a much prolonged latency occurs. Near the commencement of stimulation a temporary diminution of the latency is occasionally to be recognised. 6. We have mentioned, at the commencement of this paper, that Helmholtz, Wundt, and others regarded the strength of the shock as playing an important réle in modifying the length of latency, and we also pointed out that this view had been opposed by Rosenthal and Lautenbach. As the question appeared of importance, we directed our attention to it, in the hope that we might be able to contribute something to its elucidation. * The muscle was apparently contracting slightly when stimulation was delivered. i? Die G. Ps Yeo and: T. (Cash: Our method of procedure was to remove the secondary coil of du — Bois Reymond’s induction apparatus to a considerable distance from the primary and gradually to approximate it, testing both directions of the current in each instance till distinct contraction producing a legible curve was obtained. Hlectrodes were applied to both nerve and muscle, so that the position of the secondary coil at which direct or indirect stimulation caused contraction might be noted. A much more closely upproximated position of the secondary coil to the primary is necessary for direct stimulation to be effective than for indirect. One Daniell was employed in the earlier experiments and in the later two Grove’s elements were introduced into the primary circuit. , A contraction first occurred when the secondary coil (opening shock indirect) stood at 28 centims. No other mode of stimulation was effective till an approximation of 9 centims. was reached, when an indirect closing shock became operative. At 6 centims. direct opening shocks produced contraction, but the most powerful direct closing shocks, of which the apparatus and the single element were capable, were ineffective. The contraction here, though maximal for indirect was submaximal for direct stimulation. The shock was at no point exhausting to the muscle for the altitude and length of the contraction, except in the case of the first, which is distinctly submaximal, remain remarkably constant throughout the experiment. The total result of the experi- ment may be expressed in four figures. Gastrocnemius. Indirect stimulation: increasing strength. 1st stimulation: coil at 28 centims..... Latency=30 54," 10th ‘, if 19 sey’ eeteee o | icone 20the - . 10 sil Thame 3 \\ ceOt ee 30th is ‘5 0 spills eae o> cones or, in other words, the diminution of latency under this increase of stimulation was only ‘15, or the ‘0008”, an effect so slight that it may pass almost without notice in ordinary experiments, but is nevertheless of sufficient value in showing that an increase of intensity of stimula- tion, only carried so far as to produce a continuance of healthy re- action, still modifies the latency to a certain extent. The temperature of the room, 17°°5 C. remained constant during this observation. In another experiment, two Grove’s cells (small) were substituted for the Daniell, and thus a much greater potential was available for stimulating purposes. The muscle was uncurarised and the stimula- tion direct. On the Latent Period of Muscle Contraction. 473 Table IV.—Influence of Stimulation. D.V.=;1,". { : Secondary} Length of | Length . No. | Weight. eat y inteney: of ae ve, | Altitude. Remarks. evierms.| 20 cm. | 3°75 d. vy.) 19°4d.v.| 7:0 mm. 2 ‘: Se ts-GOn) | 120-0)" leis 0 3 i NGM 35 er MarR 3). odio 4, 4 MNP oh AE OCOn 1 B70) o 5 ii ee oso Scan © ClezG si 6 i HO oao. .. WelOr7. eal og 5 om 7 < Sey nO 10e 63) lng Bui loz Ue 8 a Geek 050-8 19705, 3| 95 0 8 9 A EOC Ose §t 12GOu | wiie26 5! a ; F R oe : rs ae i | Does not regain Re? (225 oe | aso 4 ||, tbseisee, bub 13 i Le 2-95 ” ‘a o7-0 » \ shows indica- 14 u Ga ebocswas 5 Doro wie! iy ence cos Pee 5, 245 5) [27-74 °| 16-0 2 || Oh, teat 16 i 10 Fr 2-55 A 22-5 ae 13-0 o 5) phase. 17 s TMS CO: oe | oii Salle: 3 18 & PONS Ase en 22-20. ViOsO ee 19 a TSMR SCGS, | oa ON ain. | 20 3 18, ee s a 21 re: ‘ No curve was 2 AUS Sis 3s ze) A 8 i taken at 12 cm. We have here abundant proof, that without exerting a strength of stimulation sufficient to destroy contractility, we can reduce the latency through a or the ‘0094". From the time the secqndary coil came within 4 centims. of the primary whilst it was pushed “ home,” and until it was removed again to 8 centims. from the primary, no curve produced reached the abscissa during the passage of the registering plate: there was an alarming viscosity manifested, and we feared injury to the muscle, but on distancing the induction coil a pretty fair recovery was made, the latencies rapidly lengthening, till at the position in which a value of 3°75 was first obtained, 3°8 was now recorded, the curve meanwhile, though somewhat (3°6 D.V.) lengthened, approximated to its primal form. This experiment was repeated again with curarised muscles, and the result obtained coincided with our former experience in the abridge- ment which the latency undergoes under increase of stimulation. We give, in Table V, an illustration of increase of stimulation, ultimately proving fatal to the muscle. ATA Drs. G. F. Yeo and T. Cash. Table V.—Curarised Gastrocnemius. Two small Grove’s Elements, No. | Weight. more) | ue agin et bemagiie Altitude. Remarks. coil. atency. | of curve. 1.) 10) erms| 13 corem. 163) 745) dias) -8) dewvas| geal 2 onan 2 iy 13:0 SANS 25) "ages taal meio ee 3 » I el ei yy |) AD 16m: 4 >» E250) 3 2 A ee ZOO, 21, 5 %9 LO ep Ae |) ZDHS ee 25 5, 6 PO Ok || BOO ay 7 » 9°0 ,, | 2°25 ” 19-7 ” 25, 8 ” 3:0 le2e2 ry) 17 25 >; 9 % FO, Sid oe. eee OC OF ene oT oe 10 F CFO ealez Oe e20con ee 29 ue 11 55 550) Sale2 2b aldoes: mnotnlaEoOmees The first contrac- 5 terminate tion Of ‘fhig 12 93 4-0 ,, | 2°25 226) duane Ome muscle occurred 13 se 3 10) Rsstaliic es Babi FS eeox at 25 centims. 14 > 3 OF ee leenoolen. we Wi ues of secondary 15 » AOL Bealeton 4s Ee. 26>... coil, and had a 16 a ZO sie le2i2o |e ae 26a, latency of 4 d.v. 17 5 RE Ryser RO. besa a 2a aes As curve is in- 18 55 On Pale So) a. Si 25. 3 distinct up to is) 55 OSS wo Gor s. be 20". 20 centims. La- tency is omitted. 20 35 O a is lasting con-| 16 ,, Muscle dies at | traction last stimulation. Our first latency in this chart commences with the secondary coil, 13°5 centims. from the primary, and has a value of 3°45 D.V., and this we find at 6 and 7 centims. curtailed to 2°2, the smallest figure recorded. At this point (6 centims.) the curves which have hitherto been of fairly equal lengths, though of increasing altitude, show a consider- able elevation after the active phase of contraction is over, the lever pen failing to reach the abscissa for some time after the plate has passed. The stimulation is still increased and the muscle remains longer contracted, whilst the curve falls in altitude; a stage of irrita- bility which lasts till the secondary roll has passed 15 centims., and which is attended with short though varying latencies, passes, and after a sudden and extensive prolongation of the period, the last shock delivered with the coil “ home” kills the muscle completely, the last latency being 3°65 D.V. We have here, then, a case in which the violence of the shock at last employed, kills the muscle and death is preluded by a distinct lengthening of latency, so that we cannot ascribe the changes of the earlier part of this series to morbid pro- cesses, any more than the shortening of those of the table last con- sidered, though the strength of the shock when the coils were nearly approximated was no doubt very great. We conclude, then, that the length of the latency is largely influenced by the strength of stimula- On the Latent Period ef Muscle Contraction. AT5 tion, and an abridgement of the former of more than the ;35 of a second is readily produced by strong stimulation, without inflict- ing permanent injury upon the muscle. With stimulation of a much milder character, more closely related to physiological stimulation, a very slight shortening of the latency may be observed. 7. When Helmholtz was investigating the speed of motor nerve con- ductivity, he found that in the case of man this underwent a remark- able change in the summer time, so that its velocity became 60°90 metres per second, or fully twice as much as it had been some time previously. This acceleration he attributed to the elevation in atmo- spheric temperature occurring at that season, and this conclusion led him to a theory for the different speeds of conductivity in the upper arm when the nerve is sheltered and the lower when it is more super- ficial. Troitzky, who investigated conduction in the nerve of the frog, stated that the speed was greatest between 10° and 20°, and diminished both under lower and higher temperatures. Tt will be recollected that our moist chamber was furnished with a coil of tubing, which acted as means of producing heat or co!d according to the temperature of the fluid passed through it; by means of this coil we were able to produce as extensive variations of heat or cold as our subject demanded. Water cooled by a mixture of chipped tee and salt in the one funnel, and water heated somewhat above the temperature we desired to produce in the other, enabled us by their conjoined use to hit the point we needed with precision. The atten- _ tion of one of us was fixed upon the thermometer, and at a sign from him that the mercury stood at the desired level, the pendulum was liberated and the curve registered. Some experiments were made to ascertain the effect upon exposed nerve of the temperature of the chamber, and with the results of these we will begin this section of our subject. Our Table (VI) shows the effect of a depression of the tempera- ture through 12° C. (from 17° to 5°) and of its subsequent elevation through 8° (17° to 25°) or of a total excursion through 20°. The variation of latency accompanying this change is from ‘026” (5°) to 0127” (25°), or no less than -0133" or the =; part of a second. Having taken a curve at the room temperature (17° C.), we rapidly cooled down the muscle to 5°, and then permitting it gradually to regain its normal a curve was taken at each degree; when 17° was reached we began to heat slowly tll we had raised the temperature to 25°. VOL. XXXII. 2m 476 Drs. G. F. Yeo and T. Cash. Table VI.—Effect of Heat and Cold on Gastrocnemius. Stimulation Indirect. Maximal. Length of | Length No. | Weight.| Temp. Altitude. Remarks. latency. | of curve. 1 |1@grms.| 17°C. | 2:9 d.v..| 16°5 d.v.| 22-5 mm 2 ih Bish Eye OE te gamoes loon Qin. 3 i Gig. W4-5P Aisul ears mon aitoeton,: 4 ‘ 7, Ase Sikes 5) | eon 5 5 Sg ace ak ls 297 ow se aoe Onsen 6 ”? 9 ” 44: > 25 ‘0 ” ZASO 7 £ 10. 5 (f8r85: 1 \p2acOr Ey leuicoae: Silat e 1, 375 5 eeecay eo eocoe 9 Taos Siem tel achigeiny ent OTLe) aya 1Oc is. | 3°35. | 20°01 o)-owee 11 oe 14,, |.3°25 ,, | 18°25 ,, | 19:0 ,, | Coolme below 12° 12 a LB sy bee Clee. Woe TLL eeOu ng irl ee On Onmen causes a perma- 13 . 16 Pe 2EO) ee (yt oe Dor eae Omene nent shortening. 14 z 17,, |3:0 ,, |13-4 ,, | 22-5 ,, |The length of the 15 49 1B 2, SD. ss ASSO) eS eOn Bee active curve only 16 = 19.,, Zoo 5, Ea5 os PAL WEL} eek given. 17 ? 20), (e268 1 Lo eagean s. Diaeroune 18 ” 21 rB) 2°75 ” 9 25°0 ,, 19 ”? 22 ,, 2-7 ” ”? 24°0 ,, 20 ” 23 ” 2°7 ” ” 24°25 ” 21 < 24. P25 vaeod MekoRN.. "Ned onhe 22 ‘ 25, | 2°30 ,, | 12°25,, | 24-25 ,, Let us examine the nature of the changes corresponding to our variations in temperature. dB eee die ear a 2°9 : LS? lessee ads Se WEN en 4-7 or +18 16 3 gale) 6 less ao 17.) mores Z A Oy 18. », less; 2 eis 8 - 2 19 4 a0) 9 aw 05 20 05 10 3 cay Dil 5 05 iMt i. “1 BAD, s 05 12 i 25 23 sf a0) ile “s “5 24 e 2 14 x all PAR me “2 From these figures we see that the effect of cooling for equal degrees is greater than is the effect of heating; that is to say, that while cooling through 8 degrees adds 1 D.V. to the latency, heating through 8 degrees takes only ‘7 D.V. away from it. The average effect for degree of cold is -00069”, that of heat 00048", and could we take an average of the whole 12° through which cooling was carried, the figure would rise to ‘00077’, because the addition of every On the Latent Period of Muscle Contraction. AQT degree of cold after 9° and 10° are reached, produces a more con- siderable elongation of latency. If we carry the heating much above this point, we find that there is a sudden accession of excitability of the nerve as manifested by a much elevated and prolonged curve differing also in contour from its predecessors. This condition increases to a certain point, then diminishes, and the entire death of the nerve ensues. The first indica- tion of danger occurs at about 27°, and death at 30°—31°. This muscle, however, may still be quite capable of responding to direct stimulation if the temperature be not further increased, and revives eventually. The following Table VII shows this course of events. Table VIl.—Heating carried to Death of Nerve with Measurement of Curves of Direct Stimulation subsequently taken. | No. | Weight.| Temp. th merce | renee | Atitude: Remarks. atency. | of curve. ee tOerrms: | 17°C. | 3°10 d.v.| 17-8 d.v.| 24°5 mm. 2 . eee OR Herz | .0| 2550 | 3 ¢ 19). | Ges. ep sie RRO) 4, i 20 ,, ZOO eee lon Sia ae laa o 5 - Pie io ee igri | 38-00. 6 vf DO WeDo TG RD 04 4! | B4-B | 7 i Dae Me ei) om ilu) om 35-5, 0 8 = 24 ,, Za OR ON sth || OOMOut 9 . Damen le2i-1 | | Tor Ol on | Sao « 10 s Pope eocte fe Tar) cl ais 5. 11 5 20, 45 220k aw lesen 420. Nerve irritable: 12 E Dame 2 OMe | 1869 a 540), 13 - DOMe ESrO5 Fi 19-0, ,, 156.0) ,,, 14 % 30 ,, AMS py Mera) eo tp 15 ie Sie ieee GTO ou | 50 16 - 32 ,, OF Om 5; 0) 0:0 ,, | Nerve dead. 17 < Seeks 8h by 18 45 32 5; SG en ean. is 23°5 ,, | Stimulation of muscle 19 > 31 ,, TE COR Ti LonO)\ 575, | 20-0) 5) N.B.—The muscle completely recovered. A series of curves (direct stimulation) was subsequently taken from it. Heating from 17°, at which the latency is 3°10 to 27°, reduces the latency to 2 D.V., and after this point there is again a slight increase till the death of the nerve at 31° occurs. That there is, however, a marked diminution of the latency from 20° to 27°, is plainly to be seen, as the variation is through ‘003”, and this result scarcely coincides _ with the assumption that conductivity is impaired after 20° in the case of the frog. The curarised muscle is a more fitting subject for the study of the 2M 2 478 Drs. G. F. Yeo and T. Cash. influence of temperature than is the nerve-muscle preparation, as its — mass prevents the extreme influences under which the delicate nerve suffers, being felt to such a large extent. The curve also is the expression of the actual effect of a certain temperature upon the muscle only instead of being that on both nerve and muscle. A rise or fall of temperature through a certain number of degrees has a magnified effect on the nerve-musele preparation compared to what it has on the muscle. Table VIII.—Cold and Heat on Curarised Gartroenemius. | | No. Weight. | Temp. me o Lyesug Ha Altitude. Remarks | ateney. | of curve. 1 | 10 grms.| 19°C. | 1°7 d.v.| 14:0 d.v.| 24°5 mm.| Extends below abscis- | sa, single summit. Dol TS mi. ° (al 28” (024 O- aReachtes abseissa, | single summit. 4, | - 13.5, .|-250) |5, | 2080. |22550> 5, caleiesehes abscissa, double summit. By | 2 11, | 2°05 ,, | 22°75 ,, | 26:0 ., | Does not touch absecis= sa, double summit. 6 | 4 Dig y ol BeBe by | 42 Re Asse 0 ees Do. do. eeu 7, |) 255% oy 0 38e04,0 |) 305Oune Do. ~ “de 8 | : 10) Va Cl ee 30° 28 iG a Do. do Ohl aes 12),.0 1) Selly boob e0 ol Rao Do. do 10 | ; A 2-0 : 19°8 ,, | 24°5 ,, | Almost touches ab- seissa, flat summit. eT a| , 1G «, PSADE by) 15°4 ,, | 25°5 ,, | Extends below ab- scissa,single summit. 12 “ UWSh Weegee 1200 ee 247/ ns Do. do. 20 oN teGie all teredh et Ome Do. do. We have before us the result of cooling a curarised muscle down from 19° to 7°, and then of heating it to 20°, and the figures represent fairly the changes in the curve and latency. The total addition to the latency is 8 of a double vibration, or 0044” whilst the addition m the length of the curve is 24D.V. The interesting fact is well demon- strated in this Table that the greater the influence of cooling through a given number of degrees hes been upon the latency, the greater is the effect also on the curve, so that whereas between 19° and 17°, the latency varies the ‘15 D.V., and the length of the curve increases onl 2 D.V.’s between 9° and 7° where the latency increases “2 D.V., the curve lengthens 13 D.V., but it is necessary to remember that it is exactly at this point 9—5°, that cold has such a powerful effect in prolonging the curve. The lengthening or shortening of latency and | curve accompany each other ania A pacittisea)bls precision, though it has On the Latent Period of Muscle Contraction. A479 appeared to us so far impossible to establish a constant and definite relationship between them for all temperatures and conditions. Another result otained from the curarised muscle by heating to 30° after having cooled to 11°, shows the companionship of latency and curve in their variations. Table [X.—Curarised Gastrocnemius exposed to Heat and Cold. No. | Weight. Temperature. Latency. Length. Altitude. 1 10 grms. eC By Ck ve fh SOO) Clay 18 °5 mm. 2 > Is 3°3 3 SOLOn.. SSB 5. 3 i Tee BQ del hon a 18°35, 4 ” 14 ” 2°75 oP) 23-0 ” 16 °5 9 5 ” 15 ” 2°5 ” 20-0 ” La a0) ” 6 “5 HO 5, 2-5 5 Le Gh ss Soman. 7 ” 17 2 2°5 ” i ” 19-0 »” | 8 ‘ ice SV MSV ITO 9 ” I) 2°4 » 16 0 ” 18°5 9 | 10 oy) 20 ” 2 °4 ” 14° ” 17 ‘5 re) | 11 i. Tal DEB oe siete 2ee. One 12 i 29, DOTS, oe I) TS DH Ne 10. 13 “4 23, o> iy 14 O) es 1620) 14 i 24 ,, Dealiye a ledge. leche 15 ~ 25 Fhe Dh ue hll maidens 1S One 16 26, Dene ene eloean Teo 17 a De O05 eee 6ne 17:0, 18 3 PRS) ey L°85)) 5; L2G? S, Ome 19 5 BE) berg ; Ors ID. 5 20 3 30, 16 5; PAESr,, Sore ye The latency varies through 1°39, the curve through 23:°2 D.V. The extreme prolongation of the curve at 11° and 12° is an illustration of that which we think we have seen many times, though we have not found opportunity to work out the point, viz., that if after heating a muscle, the temperature be reduced below the normal, the effect of that reduction is greater in prolonging the latency and the curve than it would have been if starting from the rormal only. The converse— for heating after cooling—appears also to hold good. If a muscle be heated or cooled to a certain temperature and be maintained at that temperature for a considerable time, does the pre- paration acclimatize itself, and do latency and curve show a tendency to return towards the normal? Our answer is that they do not. A muscle kept at 20° for 25’ gave a constant latency of 2°75 D.V., whilst the curve varied in value only through ‘2 D.V.; at 25° for 15’ the latency remained at 1°65, the length of contraction varying only through °3 D.V., the same result obtained on cooling. We conclude then that cold lengthens and heat shortens the latency, A480 Mr. E. H. Glaisher. the effect per degree of the former being greater than the latter. The shortest latency for the heated frog muscle occurs at 29—30°5°, and closely precedes rigor. Muscles maintained for a considerable time at a given elevation or depression of temperature, preserve a constant latency. Up to the present the gastrocnemius of the frog has been the only muscle upon which we have experimented, and our chief object in making this communication is to call attention to the changes in the duration of the latency brought about by varying conditions of stimulation. We hope to continue our observation by making similar experiments on different muscles of various animals, and in a future paper to enter more fully upon the changes occurring in the other phases of the contraction, for which purpose further use will be made of the tables we have the honour of laying before the Royal Society. “Formule for sn 8u, en8u, dn8u, in terms of sn wu.” By ERNEST H. GuatsHer, B.A., Trinity College, Cambridge. Communicated by J. W. L. Guatsupr, M.A, F.RS. Re- | ceived and Read June 16, 1881. § 1. In Grunert’s ‘Archiv der Mathematik und Physik,” vol. xxxvi : (1861), pp. 125-176, Baehr has given the formule for sn nw, cn nu, dn nu, in terms of sn w for the cases n=2, 3, 4, 5, 6, 7. These ex- pressions are reproduced by Cayley in a tabular form in his “ Treatise on Elliptic Functions,” Art. 109 (pp. 80-85). The object of the present paper is to give the corresponding formule i in the case of n=8. These were deduced from the formule for the case n=4 in the following manner. We have 2sn 4a en 4a dn 4u SITES 0 ss praia te a 1—* sn? 40 i 1—2 sn? 4u+ k? sn4 4 Cn. 37) eee 1—k? sn2 4 1—22? sn? 4u+ ke? sn4 4u Gita Siig ee es ee a oa 1—k? sn? 4, ; and therefore, denoting the numerators of su 4w, cn 4u, dn4u, and i. their common denominator by P, Q, R, 8 respectively, so that sn dus, cn dua, dn du= =, ae ee i ‘ Formule for sn 8u, en 8u, dn 8u, in terms of snu. 481 7 RORS find 8 ) we iin Sn ou= Ss aps a By St 2P iS PPS S!—iePé dn Se Se + Pt S!—/2P4 § 2. The numerators of sn 8u, cn 8u, dn 8u, and their common de- nominator, may therefore be deduced by combining linearly the four expressions PQRS, P*, S4, P?, S2, where P=2/ (1—2*) /(1—k?a?) x {4— (8 + 8h?) a? + 20/2x4— 20428 + (8k*+ 8h%) a9 — 448312}, Q=1— 802+ (8+ 20K?) a4— (24k? + 3214) a8 + (54+ 1625)28 — (2444+ 324%) x! + (8k*+ 20k) al? — 8h8cl4 + L8c16, R=1—8%22? + (203? + 8h4)a4— (822? 4+ 24h*) 28 + (16k? + 54h) 28 — (32K 2416) a0 + (2046 + 818) a12 —Sh8n144 18216, S=1—20#a4+ (82h?+ 32k) x6 — (16k? + 58h4+ 1645) 28 + (8244 + 32h%) 219 —20h6a)? + 18216, and « denotes, as throughout this paper, sn w. The values of PQRS, P4, S+, P?S? were calculated in the following manner : The squares P?, S*, and the products PS and QR, were first formed. Then P?, S* were multiplied together, and the square of PS was formed: the agreement of these two results verified the values of P?, S?, P?S?. The expressions for P* and S* were then obtained by squaring P? and S?; these calculations being performed in duplicate. To obtain PQRS he expressions for PS and QR were multiplied to- gether; and as a verification the product PQ was formed, and this was multiplied successively by S and R. § 5. The resulting formule are shown in the following tables, in which the mode of arrangement is almost obvious: thus, for example, the numerator of sn 8u. =2/{(1—2*) 1—#x?)} x {8 — (80+ 80h? )a? + (192 + 968%? + 1922*)24 — (128 + 24964? + 2496444 12828) x® + (1728h? —7416h4+ 1728h°) 28 + oe 87 Gi a + (BOK + 80% 8 — 8);303:60} PGGO8LT 89468 — PSLPS9L a 96GLTE oO Bea| I 4 (a) — (5) {eas 96¢E1TE ° S94ZE 3+ PSLPSST am PEGOST is SS “pid ‘or N 48 + + a O800EP VV6V6LE 8c 66ST 9TO8669 89689ET 896E9ET 9TO8669 86 LC6EST VPOVGLE O800EV ne4 a ts + 1+ O89E8¢ O0GS16P O06 TZ68T OG6ES9VV VVSELL8E 9E6L808T O89S99§ O898S96 98648081 VVSELI8E OG6EEIVP O06 T4681 00¢6S L6P O89E8S “of hale + I Free sie [hap {| 861 8CL96P GEPPS6E OGL88EPT VECbS8LE OG6ES9PP 89489299 ISOLVLSS 800E80EG 800€80EG 9SOLVL9¢ 89S892S9 OG6ESOPP VEG6S81E O¢L88EVT GEVPS6E 861967 ger ‘of » I Frtietit to gate aly stevie ate 661 I6V] 8éLT 9LTPLS G6L6V0G 9E16969 OZLS8EPL OOZTLE8T 86166EST PVEELI8E 9SOLPLSS FG08G LOV VGO8GLOV 9S0LVL9¢ PVSELI8E 8GIG6EST OOGTZ68T OZL88EVT 9616969 C6L6V06 OLIVLS 8cLT 96VG 661 “pl bee +} +) 0 pone Por et sats eeta + | + 08 896 96% 9TVL P86L8 ShOSh9. Z6L6F0B SEPPS6S 00ZS 16h PrOPELE PSLPSOL 9108669 986/808T S008808% 80088082 98628081 9108669 PSLPS9L PPGPELE 006S16F ZEPPSGE Z6LGFV0S ShOSh9 V8648 91rd 96P3 896 08 X {4 —- 1) (g@— TL) } A eng us fo 10,v.L9UIH NY tPF eier le beets Hse se se Pap + ? ! 8 08 661 S21 S241 P8618 9LIPLS 821969 os9es¢ OSO00EP PECOST 89128 966118 S96E9ST oOs9gcgs O89SS9E S96E9ET 96118 S9LGE VGGOST OSOO0EP OS9E8G 8ZLI6P GLP LS v86L48 S641 8éL G6L 08 8 iy) ee ee DS a J oe Loo” selec” yay A ha pol poh reLegh reLog% eel er? ocLorl gi trp? nye fama pr Lop? zitege” ziVoe” zrtbe@ sree” og” orlsz” gL ogh iy Acad ny dead pos” rLe" plot” pp” ple plore Zl gt of g@ of -v of 2& of oF 483 vrmule for sn 8u, cn 8u, dn 8u, in terms of snu. y a OOFO66S S9L8ZLV VPSOOGT S86P6G 9ESS9 S8ShGG PVSOO6T S9OL8SCLP O0VO66S ra a | 9600 6S16r OSF9LZ PECB6O! ZE09SGIF SPPSOSOF S00E8F6% 9LLSSTPT OF0SSOP 9LLSSTPT S0088F 62 8PPSO80F ZE0ISGLP VEZE6OL OSF9LS ZS16y 9604 ‘ol FLFR PL RP tbe de be + V8E9T 696681 66LGEOTL 6966608 OSL LS6S& 89497048 VOSGC6SIT 808L0866T OGEO88E6 COSCPELY OGEO88E6 S08L408¢66T POSZc6SLT 89149048 OGTLS6SE 6966608 G6LGEOL 6S668T VSEoT “gl Pose se dh Se se (Gea ae a se (dl aes || O9S0T 86966 P699G GL6V6G CLV6GST 8PS90P4 O8STOSGESS 888L6LES VVL66E89 O9S8SEPGEL OO9S68P8T OGILVEPIG O9TOZ9SLT OGLLVEPIG OO9S68F8T O9S8SEPZL PVL66E89 888161ES OSPOSESS SP890VL GLV6CSL 61666 VEIIG 86966 O9SOL ‘of 8896 IL81Z 89666 OVGPES CL8SE1L PI6LOPYV PO6SLICT IG8ESTES OZEPI8LS P8SL9V0G OGL6VEES OVGOL9LOL O9LI8cEsl OLSEEL6ES OOLT86E8T OVGOLOLOT OZIGPEES PSSL9F06 OGEPI8LS IG8ESVES POCSLSCL VIGLOVV GL8SE LL OPGVES 89666 II81G 8896 “pl = WO JO TOFVLIULL AT 98 9L0G IGE 88044 OVPSED CLO8VVL VE9GP9E VIVIOGI 9LES889 OGEC6LV PVSOO6T OZL8L4V8 O88z9TES 9S98EGSS 6SEcSOSITL 9S98EGSS O88c9 LES O¢L8L08 PVSOO6T OGEZ6LP 9L4ES889 VIVIVGI PCIGVIE GLOSPVI OVPSEP 88044 gore 9106 9&E a FPF] HL tL thee ti tl eti +t et ei ti tit il GS O9T 9&2 Sz1 C641 888606 9TOOLP COLPPL OFZ8L2 9609TS 80996L 89LZE OS9LZE OZSSTST OOS00SF 00ZSSL9L 008008F OZSSTST O89LZE 89LZE 80996T 9609TS OPZ8LL COIVPL 9TLOOL'P 888602 C6L1 S21 966 O9T os I “of ;+I1tirtti+idi+ti+ttl+itti¢+ + +1 ttt +1+14i Mr. E. H. Glaisher. 484 89LEE O89LZ§ O6SGIST OO800EP O0cSSZ9T OO800EP OcSSTST O89L¢6E 89LZ5 mae 4 +1tlLtttit C6 LPP? OFZ8L4 9609TS 80996T PVSOO6T OZL8L4V8 O88cC9TEs 9GI8ESSS 6SECSO8IT 9GI8ESSS O88cC91EG O¢L8LV8 VVSOO6L 80996T 9609TS OresLZ GBIVVL +L ltt tt titi titi+ 9TOOLL VEICVIE VIVINZI 9LES889 OGEC6LV V8SL9V0Z OGI6VEES OVGOLILOT O9LI8ZE8T OTSEET6ES O9LTSGE8T OVGOLOLOT OCI6VEEG P8SL9OV0G OCEC6LV 9LES889 F9VINGI VEIGVIE 9TOOLP “ord fies tae eee satel Rms [Mam ose ise | 8¢e1 6641 888606 CLO8PPT PIGLOVY POGSLSEL 9SG8ESTES OGEPI8LS PVL66E89 O9S8SEPET OO9S68P8T OGLLVEPTC OITOLIGLT OSLIVEPTG OO9S68P8T O9S8SEPCL PVLE6E89 OZEPI8LE 9S8ESPES PO6SLSST PIBLOVP GLO8PVL 888606 G6LT 8éL yd sons Mes poe ips ce) 2S |e) 9°@ 9SPE - 88044 OVVSED GL8SETT GLVEGST 8Ps90PZ O8'POSESS 888IZLTEs 89LSFOL8 POSGc6SIT 808Z0826T OZEOS8E6 GOSCPELV OGE08856 808Z0826T VO&CC6SLL 89LS70L8 S88IZLES O8VOSESS SP890P4 GLVGGST GL8S611 OVPSED 88042 9SVE 996 “ol =ngup jo LOFCALOULTL NT O9T — 9106 IT81z 89666 OVEVES GL6V6G 6S668T G6IZE0L 6966208 OGILS6SE GE09S61P 8PVVSO80P 800E8P6G 9LLSSTPT OVOSSOP 9LLSS TPT 800E8V66 SVP8080P 6E09S61V OGTLS6SE 6966608 G6IGEOL 6S668T GL6V6G OVGVESG 89666 9181S 9106 O9oT “pd + fF 1+ Pea ea el +1 +) el ee eee IT G& 988 8896 O9SOT ASTAG E996 PSs9L 960P GSL6P O8FILZS VECZ60L OOFO66S SIL8ZCLP PPSOOG6L S8ZVZE 9€¢S9 S86PZE PPSOOGT SOL8ZIV OOVO66S FESC60L O8P9OLS 6SL6V 960P PS8S9T $6996 8ZS66 O9SOT 8896 9&¢ oS I ‘or +) titi titl ti +lti tlt bela eee zeLpgh zelzo% oe Loo” gel ggh 921 go% tot poU zeleg? ozo” st Lep% gtLop? stl pre gil zp% 1% op% rI7geU zilog? ort pe” gtzeh gVog? elec” sLoz% Sy mrad glec% 9 oct p71 gre zLot® ray ha tos slat eLore zt gt ge g& ot pe sibel of ov 485 Formule for sn 8u, cn 8u, dn 8u, in terms of snu. 96090 FFSOOGT S8ZhCS — SPS9OSzFrL 9ESS9 + PCPILOP + ZGE6S99ESP S8CVES — SPS98ZFL VPSOO6GL 960P ‘od rac 4 “ard | + a | P8SS9T 9L606T GSL6V 89L8ZLV VVI8S666 V8LLOGL6 S8OEST88T “V8TTOSL6 PVI8S666 89L8ZC1P 6S T6V 94696T PSS9OL ‘ord + ir | +1+ PE99G 800666 OO9LLST O8PPPOL O8V9LS OOVO66S OPIOVS TP OSSSLVOET O8PP800PG OLZTE606G O8PP8N0V] OGSSLPOET OPIOP8SLV OOPO66S O8P9LS O8PPVOT OO9LLST 800666 PE99G “gl 86S6E I68O1G O9TG IGT IEC6S8G 80Z0GLE SPVS9G 9T8PSTs S89PTL8E GI&Sé418L1 VEIIEVS0G O8PP8O0PS S80ESTS8T O8PV800PG VCIIEP80G GLESLISLL S89VTL8E 9T8PSTS 8PT896 8060526 9EG6S8ZS O9TGIZT 9680PE 86966 “of +1+14++I+ 1+ 34+ 1+ +7++ 7+ 74+ O9SOT OO9SOT OIT86P O9TZIGL OO9ZLST 80G0SLZ VV69ETE V8L824906 VPTL9089 GLEEZI8I1 OSSSLPOET VSLLOGLZ6 GOG99ESP VSLLOSZ6 OZSSLPOST GLEEZI8IL PVIL9089 P8L82906 PV69ETE 80Z0SL2 OO9LLZST O9TELZEL O9T86P VO9SOT O9SOL “ed =LOPVUIMLOUD, WOWLUIOD OTT, eee ee eel Peat ce Pe eto fee fee 8896 ICVVS OO9SOT 9680PG 8006646 92606T OSPPPOT SPP896 V8484906 S89PTL8E OVIOVSTV VVI8S666 SP898ZPL VCVILOV SP898ZPT PVI8S66G OVIOP8TV S89VTL8& PS8Z81906 SVV8S96 OSPVVOT 9Z606T 800666 I680P] OO9SOT ISPVS 8896 a ee ee il IEE 8896 O9sot 86966 V69IG P8SE9OT 960P 6ST6V O8P9LS 9I8PSTS ONVO66S 89L861V VPSOO6T S8CPGS 9ES99 S86TGG PVSO06T 89L8ZCLP OOVO66S 9I8VSTs O8V9OLS 6SI6V 9607 V8SS9T VE99G 86966 O9SOT 8896 96E 1 “od Peon aSaesiiiee [PS a tOLtl ti titi ce% po? gv or Zoo” gc ggU ge-LogU PL pgU aol eg? 07g? gtY ep? gt LopU gr Lepe gt lore 91 Lore rrVeer ziVogU ole” ster sLogv gL ach g 1 9o¥ grav ba 9 Loc” pL eLote spre sLee sor Bd gt al ea ol pv a oF 0 486 Mr. E. H. Glaisher. $4. If k be put equal to unity the cn and dn become identical, and the formule, as is well known, assume the simple forms ae (1+a)"—(1—2)” (l+2)"+ (1l—2)* 2(1—2a?)” (l+a)"+(1—a)* - sn 7% (ce cn rhu= (k=1). Putting n=8 in these formule, we have S(a+ 7a + 7a +27) sn 8u= ee eaten 1+ 282? + 70e4+ 2826 + a Bey ee 1—42? + 67*— 426 ieee 1+282x?+ 70x*+ 28z6+ 28 When / is put equal to 1 the formule in § 3 should reduce to these expressions: and we thus obtain an important verification of their accuracy. Since the denominator of sn 8u, cn 8u, dn 8w is of the order 64 in a, itis evident that a factor of the order 56 is common to the numerator and denominator of these expressions when & is put equal to unity. By putting k=1 in the formule of § 3 and dividing the resulting ex- pression for the numerator of sn8u by 1+7z?+7z*+2° it is found that this factor is (1—z”)*8, as it should be. And it was verified by division that the expressions for the numerator of en 8u and the common denominator were equal to this factor multiplied by 1—4a? + 6z*—42%+28 and 1+ 28z?+ 70x*+ 2825 + 2° respectively. § 5. The expressions P?, S*, P*4, S* are respectively the numerators and denominators of sn?wu and of sn*tw, and it seems worth while to place on record their values, which are as follows: Formule for sn 8u, en 8u, dn 8u, in terms of snu. Bee aot J,0 a6 7,0 x8 j,9 pO? lh pl 4]4 a l8]6 9720/8 grehe ap24],8 17 26],10 28]el2 30f|4 + 128 + 384 — 176 — 512 + 128 — 912 — 176 + 384 5 ils) 284 — 1216 4328 + 6016 — 5904 + 6016 — 4328 + 1216 284 — 64 is. 32 1664 6016 R774 6016 1664 o2 k6, ke. — 1024 + 3904 + 256 — 1024. 487 Mr. E. H. Glaisher. 488 9607 P8egol 9LSV6 VSE9T 9607 wa | + + V8E9T GLSC6L GSI6V FOE86 999996 OP8E9T 80996T S8Z8PST S0996T OV8E9T 999996 VOE86 CSl6V GLSG6L V8Sé9L “orl |} + | VC99G 6S1S0E POIPSLET G6LELI GEV8I O9LSCST 9LS08S9 GL6VS8S 9S0SP COZ6LES OGSSTETIT OOZ6LEE 9S0SP GL6VS8S 9297859 O9LSCST GEP8L C6LELI PIV8LET GSESOS V699G “ef [blltit+ebaie el eel Rall 86966 088092 9S9P60T 696 L0ES 8P8IZIG * PVLTE PVEEVSS C6LLE6IL 9S9VEL6 O8 eo a ‘ 7 ‘ e . < * ‘ . Sd ; y t : aS : r # ae 4 ‘ ea . a ~ 2 - . fs Fy a Ne i ‘ ~ -a 1 INDEX, ro, VOL, x XXTEH. ABNEY (Capt.) on the effect of the spectrum on the haloid salts of silver, and on mixtures of the same, 164. Address of the President, 40. Alopecia areata, on Bacterium decal- vans : an organism associated with the destruction of the hair in (Thin), 247. Ammonia, synthesis of (Johnson), 32. Anatomy of central nervous system in vetebrate animals (Sanders), 400. of Chiton, certain points in the (Sedgwick), 121. of thymus, on the minute (Watney), 11, 349. Anniversary meeting, 39. Atmosphere, constituent of, which ab- sorbs radiant heat (Hill), 216, 435. Atmospheric temperature, comparison between diurnal ranges of, as recorded at observatories of Stonyhurst, Kew, and Falmouth, and diurnal ranges of magnetic declination as recorded at Kew Observatory (Stewart), 410. Auditors, elected, 1. report of, 39. #-Lutidine, on (Williams), 159. Bacterium decalvans, on (Thin), 247. Bakerian Lecture. Action of free mo- lecules on radiant heat, and its con- version thereby into sound (Tyndall), ao. on the chemical theory of gunpowder (Debus), 361. Balfour (F. M.) and W. N. Parker on the structure and development of Lepidosteus, 112. ' Bicket (J. H.) and E. J. Mills, re- searches on chemical equivalence. Part IV. Manganous and nickelous sulphates, 32. Bigsby (John J.), obituary notice of, Xvi. Blanford (Henry Francis) admitted, o22. Bone, propagation of heat by conduction in (Lombard), 11. Brain in rodents, comparative structur of (Lewis), 15. of the Mormyride (Sanders), 400. Brain-tissue, propagation of heat by conduction in (Lombard), il. Bramwell (Sir G. W. W.) elected, 254. British Association unit of resistance in absolute measure, value of (Rayleigh), 898. Butterflies, prehensores of male (Gosse), 23. Candidates, list of, 380. Carbon, spectrum of (Liveing and Dewar), 403. Cash (T.) and G. F. Yeo, the effect of certain modifying influences on the latent period of muscle contraction, 462. Chemical equivalence, researches on. Part IV. Manganous and nickelous sulphates (Mills and Bicket), 32. researches on. Part V. (Mills and Hunt), 32. Chemical theory of gunpowder (Debus), 361. Chiton, certain points in the anatomy of (Sedgwick), 121. Chromium and urea, on a series of salts of a base containing (Sell), 267. Coal-dust in colliery explosions, on the influence of (Galloway), 487, 490. Coal formation of Nova Scotia, explora- tion of erect trees containing reptilian remains in (Dawson), 254. Coefficients of contraction and expansion by heat of the iodide of silver, AgI, the iodide of copper, Cugly, and of five alloys of these iodides (Rodwell), 1438. Colliery explosions, on the influence of coal-dust in (Galloway), 437, 490. Comet 6 1881, photographic spectrum of (Huggins), 1. Conductors, iron and steel, prodr ction of transient electric currents in (Ewing), 21. Council, nomination of, 32. , election of, 67. A498 Culeolus, the genus (Herdman), 104. Cyanogen, reversal of spectrum of (Liveing and Dewar), 3. Cyprus, on a new mineral found in (Reinsch), 119. Dawson (J. W.) on the results of recent explorations of erect trees containing reptilian remains in the coal formation of Nova Scotia, 254. Debus (H.), chemical theory of gun- powder (Bakerian Lecture), 361. Determination of unit of resistance in absolute measure (Rayleigh), 398. Development of the ossicula auditus in the higher mammalia (Fraser), 446. Dewar (J.), manometric observations in the electric arc, 262. and G. D. Liveing, note on the reversal of the spectrum of cyanogen, 3. on the disappearance of some spectral lines and the variations of metallic spectra due to mixed vapours, 428. —on the spectrum of carbon, 403. on the spectrum of water. No. II, 274. De Watteville (A.) and A. Waller on the influence of the galvanic current on the excitability of the motor nerves of man, 353. Dinosaur, a British Wealden, osteology of Hypsilophodon Foxit (Hulke), 276. Dionza, electromotive properties of leaf of (Sanderson), 148. Edinburgh (Duke of) elected, 421. Egerton (Sir Philip de Malpas Grey), obituary notice of, xxii. Electric arc, manometric observations in (Dewar), 262. conductivity of glass, variation of (Gray), 256. currents in iron and steel con- ductors, production of, when mag- netised (Ewing), 21. Electrical storage battery, a new (Sut- ton), 187, 257. Electrolytes, magnetised, effects of trans- mitting electric currents through (Gore), 151. Electrolytic diffusion of liquids (Gore), 140. Electromotive properties Dionzea (Sanderson), 148. Ethylene chlorhydrin, action of, upon the bases of the pyridine series and on quinoline (Wurtz), 448. Ewing (J. A.) on the production of transient electric currents in iron and steel conductors by twisting them of leaf of INDEX. when magnetised or by magnetising them when twisted, 21. Excretion of nitrogen by the skin (Power), 354. Fawcett (Henry) elected, 254; ad- mitted, 341. Fellows det zased, 39. elected, 40. number of, 68. Financial statement, 69—71. Flight (W.), report of an examination of the meteorites of Cranbourne, Aus- tralia ; of Rowton, Shropshire; and of Middlesbrough, Yorkshire, 343. Foreign members deceased, 40. elected, 39. Foreign Office, letter to the President from, 1. Formule for sn 8, cn Su, dn 8u, in terms of sn w (Glaisher), 480. Forsyth (A. R.), memoir on the theta- functions, particularly those of two variables, 206. Fossil tusk of an extinct proboscidian mammal (Owen), 448. Frankland (E.) on measuring the re- lative thermal intensity of the sun, and of a self-registering instrument for that purpose, 331. Fraser (A.) on the development of the ossicula auditus in the higher mam- mala, 446. Frog, rhythm of heart of, and the nature of action of vagus nerve (Gaskell), SE). Fund, Government (4,000/.), account of appropriations from the, 77. Fungus of ringworm, the (Thin), 234. Galloway (W.) on the influence of coal- dust in colliery explosions, 437, 490. Gas, movement of, in “‘yacuum dis- charges”? (Spottiswoode and Moul- ton), 453. Gaskell (W. H.) on the rhytb - . ‘ ~ % ee CONTENTS (continued). PAGE III. An Attempt at a Complete Osteology of Hypsilophodon Fowxii, a British Wealden Dinosaur... By J. W. Hunks, F.RS. . f : ; . 276 IV. The Influence of Stress and Strain on the Action of Physical Forces. By HERBERT Tomiinson, B.A. ; ; . 3 . : : . 276 List of Presents . : . : : : : 3 ; E . 285 On the Limit of the Liquid State. By J. B. Hannay, F.RS.E., &e. . . 294 February 2, 1882. I. Sur les Surfaces Homofocales du Second Ordre. By Lieut.-Colonel A. MannuetM, Professor in the Ecole Polytechnique. : : - 322 II. On Measuring the relative Thermal Intensity of the Sun, and on a Self- Registering Instrument for that purpose. By HE. Franxuanp, D.C.L., E.RS. : : : : ; ; 2 ; : » 331 February 9, 1882. I, Note on Mr. Russell’s paper, “ On certain Definite integrals. No. 10.’ By Wixii1am Srorriswoope, M.A., D.C.L., LL.D., Pres. B.S. . . 841 II. Report of an Examination of the Meteorites of Cranbourne, Australia ; of Rowton, Shropshire ; and of Middlesbrough, in Yorkshire. By Water Fricut, D.Sc., F.G.8., of the Department of Mineralogy, British Museum, South Kensington . ‘ : : : - . 3843 February 16, 1882. I. Cn Impact with a Liquid Surface. By A. M. WortHineton, M.A. . 347 Tf. The Minute Anatomy of the pobaee By Hersert WAtNEY, M.A., M.D. Cantab. . : ; : : : ee : . 3849 Tit. On the Influence of the Galvanic Current on the Excitability of the Motor Nerves of Man. By Atvcustus Water, M.D., and A. DE WaAtTTEvitiy, M.A., BSe. . : é : 2 : : : . 353 TY. On the Excretion of Nitrogen by the Skin. By J. Byrne Power, meses. : : : : : : : ; : ; . 854 February 23, 1882. TE Bakerian Lecture on the “Chemical Theory of Gunpowder.” By Professor H. Dresus, Ph.D., F.R.S. . : : ‘ ; : : caok List of Presents j 4 ; : : : . : f : So EK GOVERNMENT GRANT AND GOVERNMENT FUND FOR THE PROMOTION OF SCIENTIFIC RESEARCH. 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On Sale by Murray, Albemarle Street, and Triibner and Co., Ludgate Hill. HARRISON AND SONS, 45 & 46, ST. MARTIN’S LANE, W.C., AND ALL BOOKSELLERS. 1 ae PROCEEDINGS OF THE ROYALE SOCIETY. VOL. XXXIT. No. 219. 4 , CONTENTS. March 2, 1882. Disease.’ By Professor T. H. oe ED ERS a 2. : . 381 ITI. On the Conservation of Solar Energy. By C. Wint1Am Siemens, D.C.L., LL.D., F.R.S., Mem. Inst. C.E. . : ; : ; : : . 3889 March 9, 1882. I. Experiments to Determine the Value of the British Association Unit of Resistance in Absolute Measure. By Lorp Raytzicn, F.R.S., Pro- fessor of Experimental Physicsin the University of Cambridge . . 398 II. Contributions to the Anatomy of the Central Nervous System in Verte- brate Animals. Sub-section I. Teleostei. Appendix. On the Brain of the Mormyride. By ALFRED SanpERs, M.R.C.S. - : . 400 III. On the Spectrum of Carbon. By G. D. Livetne, M.A., F.R.S., Professor of Chemistry, and J. Dewar, M.A., E.RS., J idee ee University of Cambridge . : : : . : 5 : 403 IV. Preliminary Report to the Solar Physics Committee on a Comparison for Two Years between the Diurnal Ranges of Magnetic Declination as recorded at Kew Observatory, and the Diurnal Ranges of Atmos- pheric Temperature as recorded at the Observatories of Stonyhurst, Kew, and Falmouth. By Batrour-Stewart, LL.D., F.R.S., Pro- fessor of Physics, Owens College, Manchester . : : . 410 For continuation of Contents see 3rd and 4th pages of Wrapper. Price Six Shillings. re, ye hPa pacze A PHILOSOPHICAL TRANSACTIONS. ConTENTS OF Part III, 1881. XII. Researches in Spectrum Analysis in connexion with the Spectrum of the Sun.—No. V. By J. Norman Locxyer, F.R.S. XIII. Researches on the Minute Structure of the Thyroid Gland. By EH. Crzss- WELL BABer, M.B., Lond. uf XIV. On Toroidal Functions. By W. M. Hicxs, M.A., Fellow of St. John’s College, Cambridge. XY. Polacanthus Fowii, a large undescribed Dinosaur from the Wealden Forma- tion in the Isle of Wight. By J. W. Hutxz, F.R.S. XVI. On the Histology and Physiology of Pepsin-forming Glands. By J. N. Lane Ley, M.A., Fellow of Trinity College, Cambridge. XVII. Memoir on Abel’s Theorem. By R. C. Rows, M.A., Fellow of Trinity College, Cambridge. Addition to Mr..Rowex’s Memoir. By Professor Cayney, F.R.S. XVIII. On Riccati’s Equation and its Transformations, and on some Definite Integrals which satisfy them. By J. W. L. Guaisuer, M.A., F.BS., Fellow of Trinity College, Cambridge. XIX. THE Croonran Lecrurn.—Observations on the Locomotor System of Echinodermata. By Groner J. Romanes, M.A., F.R.S., and Professor J. CossaR Ewart, M.D. XX. On the Influence of the Molecular Grouping in Organic Bodies on their Absorption in the Infra-red Region of the Spectrum. By Captain Apsney, R.E., F.R.S., and Lieut.-Colonel Frstine, R.E. Index to Volume. Price £2 2s. Part I, 1882, will be published shortly.’ Extra volume (vol. 168) containing the Reports of the Naturalists attached to the Transit of Venus Expeditions. Price £3. Sold by Harrison and Sons. Separate copies of Papers in the Philosophical Transactions, commencing with 1875, may be had of Triibner and Co., 57, Ludgate Hill. 4 3 CONTENTS (continued). _ March 16, 1882. ° I, Sur les Centres des Courbure Principaux des Surfaces Homofocales du Second Ordre. By Lieut.-Colonel A. MANNHEIM, Professor in the Ecole Polytechnique II. Note on the Photographic Spectrum of the Great Nebula in Orion. By Wiiiiam Hvaeerns, D.C.L., LL.D., F.R.S. : ‘ : III. Gn the Disappearance of some Spectral Lines and the Variations of Metallic Spectra due to Mixed Vapours. By G. D. Liverne, M.A., F.R.S., Professor of Chemistry, and J. Dewar, M.A., F.R.S., Jack- sonian rc fossbr, University of Cambridge . March 23, 1882. I, On the Constituent of the Atmosphere that Absorbs Radiant Heat. II. By S. A. Hitt, Meteorological ee North-West Provinces and Oudh . Ti. On the Influence of Coal-dust in Colliery Explosions. No. IV. By W. GALLOWAY. March 30, 1882. I. On the Development of the Ossicula Auditus By ALEXANDER FRASER, M.B., &c., Senior Owens College, Manchester II. Description of the Fossil Tusk of an extinct Proboscidian Mammal (Notelephas australis, Ow.), from Queensland, Australia. By Pro- fessor OWEN, C.B., F.R.S., &e. in the Higher Mammalia. Demonstrator of Anatoray, III. Action of Ethylene Chlorhydrin upon the Bases of the Pyridine Series and on Quinoline. By Professor ADoLPH WuRtTZ, For. Mem. B.S. IV. On the Movement of Gas in “Vacuum Discharges.” By Witi1am SPOTTISWOODE, P.R.S., and J. FtercHER Movttoy, F.R:S. List of Presents 4 ; : : , 8 The Effects of certain Modifying Influences on the Latent Period of Muscle Contraction, By Grratp F. Yro, M.D., F.R.C.S., and THEODORE CasH, M.D. - Formule for sn 8, cn 8u, dn 8w, in terms of sn u, B.A., Trinity College, Cambridge. By Ernest H. GuaisHER, PAGE 421 4.25 428 446 448 462 480 CONTENTS (continued). PAGE | On the Influence of Coal-dust in Colliery Explosions. No. III. By W. GALLOWAY (Plate 4) . 490 Index . ; ; ; : ; F : : ; ; : ; . 407 Title and Contents. Fellows of the Royal Society desiring to have direct information, by Post card, of the Papers to be read at the Ordinary Meetings of the Society, may obtain it by sending their names to Messrs. Harrison and Sons, Printers, 45, St. Martin’s Lane, W.C. Now published. Price 4s. CATALOGUE OF THE SCIENTIFIC BOOKS IN THE LIBRARY OF THE ROYAL SOCIETY. First SEcrion :-——Containing Transactions, Journals, Observations and Reports, Surveys, Museums. CATALOGUE OF SCIENTIFIC PAPERS, COMPILED BY THE ROYAL SOCIETY. | Published by Her Majesty’s Stationery Office. 8 vols., 4to. 1800—1878. Per vol.: 20s., cloth ; 28s., half-morocco. On Sale by Murray, Albemarle Street, and Tribner and Oo., Ludgate Hill. HARRISON AND SONS, 45 & 46, ST. 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