L. P n yj THE LONDON, EDINBURGH, and DUBLIN PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. CONDUCTED BY SIR DAVID BREWSTER, K.H. LL.D. F.R.S.L.&E. &c. RICHARD TAYLOR, F.L.S. G.S. Astr.S. Nat.H.Mosc. &c RICHARD PHILLIPS, F.R.S.L.&E. F.G.S. &c ROBERT KANE, M.D. M.R.I.A. " Nee aranearum sane textus ideo melior quia ex se fila gignunt, nee noster vilior quia ex alienis libamus ut apes." Just. Lips. Polit. lib. i. cap. 1 . Not. VOL. XXI. NEW AND UNITED SERIES OF THE PHILOSOPHICAL MAGAZINE, ANNALS OF PHILOSOPHY, AND JOURNAL OF SCIENCE. JULY— DECEMBER, 1842. LONDON: RICHARD AND JOHN B. TAYLOR, RED LION COURT, FLEET STREET, Printers and Publishers to the University of London; SOLD BY LONGMAN, BROWN, GREEN, AND LONGMANS ; CADELL; SIMPKIN, MARSHALL AND CO.; S. HIGHLEY ; WHITTAKER AND CO.; AND SHERWOOD, GILBERT, AND PIPER, LONDON : BY ADAM AND CHARLES BLACK, AND THOMAS CLARK, EDINBURGH; SMITH AND SON, GLASGOW ; HODGES AND SMITH, DUBLIN : AND G. W. M. REYNOLDS, PARIS. The Conductors of the Philosophical Magazine have to acknowledge the editorial assistance rendered them hy their friend Mr. Edward W. Brayley, F.L.S., F.G.S., Assoc. Inst. C. E. ; Member of the American Philosophical Society, and Corresponding Member of the Philosophical Society of Basle, &c. Librarian to the London Institution- CONTENTS OF VOL. XXI. NUMBER CXXXV.— JULY, 1842. Page Prof. D. P. Gardner on the Influence of the Dew-point on Ve- getables, considered especially with reference to their Tem- perature 1 Messrs. W. Francis and H. Croft's Notices of the Results of the Labours of Continental Chemists (continued) 15 Mr. Galloway's Further Remarks on Fernel's Measure of a Degree, in Reply to Professor De Morgan's Letter in the Number for May 22 The Rev. D. Williams's Supplementary Notes on the true Posi- tion in the " Devonian System " of the Cornish Killas .... 25 The Rev. P. Kelland's Note on Fluid Motion 29 Prof. Dove's Experiments in Magneto -Electricity, illustrative of a Passage in Professor Faraday's Researches 33 Dr. R. Kane's Note on the Composition of the Basic Sulphate of Mercury, or Turpeth Mineral 35 Mr. T. S. Davies on Pascal's Mystic Hexagram 37 Mr. W. H. Balmain's New Process for Preparing Oxygen. ... 42 Mr. S. M. Drach on Sir D. Brewster's Deductions from the Hourly Observations at Leith in 1824-25 43 Mr. Earnshaw on the Motion of Luminous Waves in an Elastic Medium, consisting of a system of detached particles, sepa- rated by finite intervals 46 Proceedings of the Royal Society 50 1» Royal Astronomical Society 56 London Electrical Society 61 Royal Irish Academy 64 New Books : — Howard's Cycle of Eighteen Years in the Seasons of Britain 69 On the Red Molybdate of Lead, by If. G. Rose 73 Method of distinguishing between weak Solutions of Nitrates and Chlorates, by M. Vogel, jun 74 On the Existence of Sulphur in Plants 74 Action of Salts on Living Plants 76 On Chlorite and Repidolite, by M. Kobell 76 Analysis of theTachylyte of Vogelsgebirge, by M. Klett .... 77 Analysis of Native Aluminates 78 Meteorological Observations for May 1842 79 Meteorological Observations made at the Apartments of the Royal Society by the Assistant Secretary, Mr. Roberton ; by Mr. Thompson at the Garden of the Horticultural Society at Chiswick, near London; by Mr. Veall at Boston; by the Rev. W. Dunbar at Applegarth Manse, Dumfries-shire ; and by the Rev. C. Clouston at Sandwick Manse, Orkney .... 80 a 2 IV CONTENTS OF VOL. XXI. Page NUMBER CXXXVL— AUGUST. M. Hess on the Scientific Labours of Jeremias Benjamin Richter. Addressed to the Imperial Academy of Sciences of St. Peters- burg, at the public sitting of Dec. 29, 1840 81 Mr. J. R.Christie on the Extension of Budan's Criterion for the Imaginary Roots, and a new Method of effecting the Se- paration of the nearly equal Roots of a numerical Equation 96 The Rev. Prof. Challis on the Analytical Condition of the Rec- tilinear Motion of Fluids 101 Mr. Gulliver's Contributions to the Minute Anatomy of Ani- .mals. No. II 107 Mr. Baily's Account of some Experiments with the Torsion-rod, for determining the Mean Density of the Earth Ill Prof. Powell's Note on Mr. Earnshaw's Paper in Phil. Mag. for April 1842 122 The Rev. P. Kelland's Reply to some Objections against the Theory of Molecular Action according to Newton's Law . . 124 Mr. C. Hood on some peculiar Changes in the Internal Struc- ture of Iron, independent of, and subsequent to, the several Processes of its Manufacture » . . 130 The Rev. Humphrey Lloyd's Notice of a remarkable Magnetic Disturbance which occurred on the 2nd and 4th of July, 1842 137 Proceedings of the Geological Society 141 American Philosophical Society 150 Fourth Meeting of the Italian Congress of Men of Science. ... 153 On the Earthquake felt in parts of Cornwall, on February 17, 1842 153 On the Blue Colour of Ultramarine, by M. Eisner 156 Preparation of Oxichloric Acid, by M. Ad. Nativelle 157 On the Action of Water on Lead, by Prof. Christison 158 Apothecaries' Hall : appointment of Mr. Warington 159 Meteorological Observations for June 1842 159 Table 160 NUMBER CXXXVIL— SEPTEMBER. Mr. W. Francis's Chemical Examination of the Fruit of Meni- spermum Cocculus (Semina Cocculi Indici) 161 Mr. Gulliver's Contributions to the Minute Anatomy of Ani- mals. No. Ill 168 Mr. F. C. Calvert on the Preparation of Quina and Cinchonia 171 Prof. J. Booth on a Theorem in Analytic Geometry 176 Mr. Darwin's Notes on the Effects produced by the Ancient Glaciers of Caernarvonshire, and on the Boulders transported by Floating Ice 180 Mr. J. Rees's Application t i particular instances of the general Formula for eliminating the Weights of Mixed Bases 188 CONTENTS OF VOL. XXI. V Page Mr. T. S. Davies on the Employment of Polar Coordinates in expressing the Equation of the Straight Line, and its appli- cation to the proof of a property of the Parabola 190 Mr. R. Warington on the Change of Colour in the Biniodide of Mercury 192 Mr. H. Croft on a new Oxalate of Chromium and Potash .... 197 Mr. R. "Warington's additional Observations on the Red Oxalate of Chromium and Potash 201 The Rev. P. Kelland's Reply to some Objections against the Theory of Molecular Action according to Newton's Law . . 202 Sir D. Brewster on the Connexion between the Phenomena of the Absorption of Light and the Colours of thin Plates .... 208 Mr. Earnshaw on the Theory of the Dispersion of Light ; in reply to Prof. Powell's Note 217 Mr. H. A. Goodwin's Proof of Professor Wallace's Property of the Parabola 219 Proceedings of the Royal Society 220 Royal Irish Academy 228 On Curcumine, by M. Vogel, jun 233 On the Action of Acids on Curcumine, by M. Vogel, jun 234 On the Action of Alkaline Substances on Curcumine 235 Insoluble Salts of the Alkaline Earths dissolved by Hydrochlo- rate of Ammonia and Chloride of Sodium 236 Production of Formic Acid in Oil of Turpentine 236 Precipitation of certain Salts by excess of Acids, by M. Wacken- roder 236 Solubility of Salts in Pernitrate of Mercury 237 On Laurostearine, by M. Marsson 237 On Laurostearic Acid, by M. Marsson 238 On the Presence of Antimony in Arsenious Acid 238 Discovery of a new Metal, Didym 239 Meteorological Observations for July 1842 239 Table 240 NUMBER CXXXVII I. —OCTOBER. Mr. Gulliver's Contributions to the Minute Anatomy of Ani- mals. No. IV 241 M. Dufrenoy's Description of Greenovite. 246 Mr. Smee's New Definition of the Voltaic Circuit, with Formulae for ascertaining its Power 248 The Rev. P. Kelland's Reply to some Objections against the Theory of Molecular Action according to Newton's Law. . . . 263 Mr. W. H. Balmain's Observations on the Formation of Com- pounds of Boron and Silicon with Nitrogen and certain Metals 270 Prof. Miller on the Optical Constants of Tourmaline, Dioptase and Anatase 277 VI CONTENTS OF VOL. XXI. Page Messrs. W. Francis and H. Croft's Notices of the Results of the Labours of Continental Chemists (continued) 278 Mr. John Phillips on the Occurrence of Shells and Corak in a Conglomerate Bed, adherent to the face of the Trap Rocks of the Malvern Hills 2 88 Prof. MacCullagh on the Dispersion of the Optic Axes, and of the Axes of Elasticity, in Biaxal Crystals 293 Mr. G. G. Stokes's Remarks on a paper by Professor Challis, *' On the analytical Condition of the Rectilinear Motion of Fluids" 297 The Rev. H. Moseley on Conch yliometry 300 Proceedings of the Geological Society 306 London Electrical Society 310 Chemical Society 313 Bichloride of Hydrogen 320 On the Action of Chlorides upon Protochloride of Mercury . . 320 On Cinchovatina — a new Vegetable Alkali 323 Preparation of pure Potash and Soda 324 Detection of Iodine in Bromides 324 Preparation of Ferrocyanic Acid and Ferridcyanide of Potassium 325 Obituary 327 Meteorological Observations for August 1842 327 Table 328 NUMBER CXXXIX. -NOVEMBER. Letter addressed by M . Edmond Becquerel to the Editors of the Annales de Chimie et de Physique, in Reply to Mr. Daniell's Letter to Mr. R. Phillips on the Constant Voltaic Battery, inserted in the Phil. Mag. for April 1842 329 Prof. Grove's Remarks on a Letter of Professor Daniell con- tained in the Philosophical Magazine for April 333 Mr. H. Fox Talbot on the Iodide of Mercury 336 On the Progress of Embryology in the Year 1840 337 Mr. Earnshaw on the Theory of Molecular Action according to Newton's Law : in Reply to Professor Kelland 340 The Rev. M. O'Brien's Additional Remarks upon a Com- munication of Professor Kelland, published in the Phil. Mag. for May last 342 Prof. Kelland's Vindication of himself against the Charges of the Rev. M. O'Brien 344 Dr. Draper on certain Spectral Appearances, and on the disco- very of Latent Light 348 Dr. M. Barry's Note regarding the Structure of Muscle 351 Dr. G. Fownes on the Preparation of Artificial Yeast 352 Mr. H. Croft on some Salts of Cadmium 355 CONTENTS OF VOL. XXI. Vll Page Mr. Murchison on the Salt Steppe south of Orenburg, and on a remarkable Freezing Cavern 357 Extracts from a Letter addressed by Sir J. F. W. Herschel to Mr. Murchison, explanatory of the Phenomena of the Freezing Cave of Illetzkaya Zatchita 359 Sir J. F. W. Herschel on some Phenomena observed on Glaciers, and on the internal Temperature of large Masses of Ice or Snow, with some Remarks on the natural Ice -caves which occur below the limit of perpetual Snow 362 Proceedings of the Geological Society 365 Chemical Society 378 Royal Irish Academy 389 — Royal Astronomical Society 397 Institution of Civil Engineers 401 London Electrical Society 404 New Books : — Newman on the Difficulties of Elementary Geo- metry, &c. — Logarithmic and Trigonometric Tables, &c. . . 405 Prof. MacCullagh on the Law of Double Refraction 407 Atomic Weight of Elements 409 On a very curious Fact connected with Photography, disco- vered by M. Moeser of Koenigsberg, communicated by Prof. Bessel to Sir D. Brewster. 409 Use of Iron Wire for Secondary Electro-magnetic Coils 411 Non-conversion of Calomel into Sublimate by the Alkaline Chlorides 411 Method of distinguishing Zinc from Manganese in Solutions containing Ammoniacal Salts, by M. Otto 412 On MM. Varrentrapp and Will's Method of determining Azote in Organic Analyses, by M. Reizet 412 New Double Salt of Soda and Protoxide of Platina 413 Composition of Conia 414 Mr. Luke Howard's Cycle of Eighteen Years in the Seasons of Britain 415 Meteorological Observations for September 1842 415 Table 416 NUMBER CXL.— DECEMBER. Prof. Grove on a Gaseous Voltaic Battery 417 Prof. Daniell on the Constant Voltaic Battery 421 The Rev. P. Kelland on certain Arguments adduced in the last Number of the Philosophical Magazine 422 The Rev. Prof. Challis on the Analytical Condition of Rectilinear Fluid Motion, in Reply to Mr. Stokes's Remarks 423 Dr. A. Waller's Experiments on the coloured Films formed by Iodine, Bromine, and Chlorine upon various Metals 426 Mr. Earnshaw's Reply to Professor Kelland's Defence of the Newtonian Law of Molecular Action 437 The Rev. J. Booth on a Theorem in Analytical Geometry .... 444 Vlll CONTENTS OF VOL. XXI. Page Messrs. W. Francis and H. Croft's Notices of the Results of the Labours of Continental Chemists (continued) 446 Dr. Draper on a new Imponderable Substance, and on a Class of Chemical Rays analogous to the Rays of Dark Heat .... 453 Mr. R. Hunt on Thermography, or the Art of Copying En- gravings, or any printed Characters from Paper on Metal Plates ; and on the recent Discovery of Moser, relative to the formation of Images in the Dark 462 Mr. Hopkins on the Elevation and Denudation of the District of the Lakes of Cumberland and Westmoreland 468 Proceedings of the Royal Astronomical Society 477 London Electrical Society 484 Cambridge Philosophical Society 485 Use of Sulphate of Ammonia in Agriculture 488 Chloride of Gold as a Test of certain Vegetable Alkalies .... 489 Non-Decomposition of Vegetable Alkalies by exposure to Fer- menting Bodies ■ , 490 Preparation and Composition of Pepsin 491 Action of Chlorides on some Mercurial Compounds, by M. Mialhe 492 On a new Mode of forming Ammonia, by M. Reizet 495 Meteorological Observations for October 1842 495 Table 496 NUMBER CXLL— SUPPLEMENT TO VOL. XXL Prof. Marianini on the Currents produced by the Actuation or Induction of instantaneous Electric Currents 497 Proceedings of the Royal Astronomical Society 510 Royal Irish Academy 532 Geological Society 540 Index 562 PLATE. I.— Linear Solar Spectra with their corresponding Tithonographs ; illus- trative of a paper by Dr. Dkaper. Errata. Page 43, line 13 from the bottom,/or (*+T)' read e (*+T)\ 44, — 3, put sign + before \/ . 55, — 7 from the bottom, instead of " M. Catalan," read " Pro- fessor MacCullagh." 176, line 13,/or quina read citichonia. 473, line 4 from the bottom,/or Penim read Penine. 529, line 2 from the bottom,/or node read note. THE LONDON, EDINBURGH and DUBLIN PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. [THIRD SERIES.] JULY 1842. I. On the Influence of the Dew-point on Vegetables, considered especially with reference to their Temperature. By D. P. Gardner, M.D., Professor of the Physical Sciences, fyc. in Hampden Sidney College, tyc, Corresponding Member of the New York Lyceum qf Natural History*. HPHE object of this paper is to establish the mutual relation existing between the temperature of plants f, their eva- poration, and the amount of vapour existing in the atmosphere. The subject will be examined under four heads, which have been suggested by the results of the experiments instituted, and are therefore gradual developments of the proofs by which the connexion between the dew-point and temperature of plants is sought to be established. 1st. Certain vegetables are without any specific heat. 2ndly. The variations plus or minus the atmospheric tem- perature observable in plants are owing chiefly to the state of the dew-point, its elevation causing an increase of heat by checking evaporation, and its depression by favouring evapo- ration producing coldness ; in other words, the rate of evapo- ration, and its effect in producing a decrease of temperature in plants, is directly as the greatness of the drying power, and inversely as its diminution. 3rdly. The sensible heat of plants is directly as the atmo- spheric temperature, and the chemical action going on in their cells ; and inversely as the evaporation, radiation and conduc- * Read before the Linnsean Society, November 16th, 1841, and now com- municated at the request of the Author, by J. J. Bennett, Esq., Sec. L.S. t On the subject of the heat of plants, see Meyen's Report for 1839, in the Annals and Magazine of Natural History, vol. viii. p. 27 ; also the original paper by Vrolyk and De Vriese, in the same work, vol. vii. p. 161 — Edit. Phil, Mag, S. 3. Vol. 21. No. 135. July 1842. B 2 Professor Gardner on the Influence of the Dew-point tion of the soil and surrounding air : to this we add, chemical action increases with atmospheric temperature, &c. &c, and consequently the amount of heat resulting therefrom. 4thly. A review of the foregoing doctrine, with some re- marks on apparent anomalies. § I . That certain Vegetables are without any specific heat. A number of insulated measures of the temperature of flowers has hitherto been admitted into the books on vege- table physiology as the whole of our information on the sub- ject of vegetable heat; and these measures have been re- ceived with distrust or altogether denied. M. de Lamarck observed an increase of temperature in the spadix of Arum vulgare, which M. Sennebier afterwards measured and found equal to 7° C. above the atmosphere. The German natu- ralist Schultz found a flower of Calladium pinnatifidum at 19° to 20° C. when the surrounding air was only 15° C. Messrs. Hubert and Bory measured the temperature of the spadix of Arum cordifolium in the Isle of France, and found it at sun- rise 4"Jf° to 49° C. ; the atmospheric temperature being only 19° C. M. de Saussure carried his experiments further, and with the differential thermometer ascertained an increase of~°C. in the male flowers of the melon and other Cucurbitaceae. Hypotheses have not been wanting to explain the reason why flowers should enjoy a more elevated temperature than the other parts of the plant. Mr. Murray imagined it was due to their colour. Brongniart ascribed it to the increased action of the molecules interested in the process of fecunda- tion. Others have adopted the more plausible idea, that it de- pended upon increased chemical action, as the absorption of oxygen by the petals, &c. of the flower. But Messrs. Treviramis, Goppert and Schubler, altogether deny that flowers give any indications of an increase of tem- perature. M. Aug. de Candolle ascribes this denial to the erroneous conclusions at which these botanists arrived from experimenting on imperfect plants ; since his experience at Montpellier had led him to the same opinion as Saussure and others. Placed in so embarrassing a situation, our only resource was to undertake a new series of experiments upon the sub- ject ; for although the mass of evidence appears to be in fa- vour of the existence of a specific temperature in flowers, yet the measures given are too dissimilar to prove satisfactory, and the experiments appear to have been performed in too loose a manner to silence opposition. The mere introduction of a thermometer into a flower is a process undeserving any on Vegetables, with reference to their Temperature. 3 serious attention : the state of the atmosphere has been omitted, and in other respects the data are so imperfect, as to exclude the possibility of our repeating any of the experiments given under similar circumstances. The instrument with which their measures have been made is altogether too bulky in such delicate researches ; for al- though the bulb of a thermometer may be thrust into a pump- kin flower or tulip with tolerable facility, yet the contact of the circumambient air is not completely cut off by the shape of the flower ; and if the fingers or any other contrivance be used as a means of closing the corolla upon the thermo- meter, the temperature of the new body complicates the result. Even when introduced with all care, a bulk of mer- cury or air of as many cubic lines as the flower has super- ficial measure, in either case an imperfect conductor, can only give a doubtful result. It is too large in most cases, and must be confined to experiments upon a few scattered flowers ; nor can it in any instance be made use of to obtain a set of mea- sures over the whole plant ; most stems would be crushed in attempting to introduce it ; and even if we succeeded so far, the measure obtained must be imperfect, from the injury in- flicted upon the plant and the small amount of mercury or air in absolute contact. These considerations have induced me to make use of a thermo-electric pair and the galvanometer as the most suitable thermoscope. The pair consists of a tinned iron and copper wire, each y^th of an inch in diameter, soldered together at one extremity with tin for T\,th of an inch, and sharpened so as to enter with slight force any part of a plant ; the wires used were about nine inches long, and were passed through a large bung, so that the fingers might not approach the junction, the cork serving as anon-conducting handle, and being sufficiently re- moved to hinder the possibility of producing a current of ther- mo-electricity by radiation from the hand. The galvanometer employed was the simple multiplier of Schweigger ; the axis being suspended by a fibre of raw silk and bearing two needles perfectly astatic, and also at the lower end a parallelogram of tin-foil which was immersed in a vessel of water beneath the galvanometer ; the object of this addition is to steady the vibrations of the needles, as shown by Dr. Draper (Phil. Journ.). The whole arrangement was covered by a glass bell-jar, having a graduated arc pasted on the inside at an appropriate height, which by moving the glass vessel can be brought to any place so as to arrange the zero point with great facility ; the upper needle also bore a fine wire standing up at right angles from its extremity, which as the needle is B2 4 Professor Gardner on the Influence of the Dew-point deflected plays across the arc and tends to assist the admea- surement. The thermo-electric pair and galvanometer can be made an extremely delicate differential thermometer ; and from ex- periments already made by Drs. Forbes, Ritchie, Draper, &c., we are justified in stating that the degree of variation of the astatic needles is very uniform for equal increments of heat, in cases where the total amount of variation is as limited as in the following. In obtaining the numbers of the tables, or the measures of temperature, the pointed extremity of the pair was thrust into the parts of the plant specified, care being taken to avoid contact by the fingers with either the plant or thermoscope ; the numbers given are the mean of at least five measures made by forming and breaking the electric circle. The same pair and galvanometer were used throughout, and the value of a degree of the index equals two elevenths of a degree of Fahr- enheit, or 1° F. = 5°' 5 galvanometer. It is well to observe here that the whole of the junction of the thermo-electric pair must be introduced into the plant, otherwise the current of electri- city does not circulate freely through the length of the wires, but passes round from the warm to the cold parts of the junc- tion, forming a circle that does not include the galvanometer, and therefore producing no deflection of the needles. The dew-point marked in the tables was taken immediately before and after each series of measures, and if any difference existed, the mean adopted. The height of the thermometer is marked both at the time of the deposit of dew upon the exterior of a glass of iced water and its vanishing. The drying power, which is Dr. Dalton's expression for the difference between the dew-point and at- mospheric temperature, is also marked in the tables ; and it is well to remark, that that great philosopher has ascertained that the amount of evaporation is the same for all temperatures if the drying power be the same. The experiments were performed in the shade, every dis- turbing cause, as currents of air, motion, &c. being avoided. The thermometer hanging at the side of the galvanometer, and the dew-point, &c, were all estimated at the same spot. Arum Walteri (foliis sagittatis) was preferred for experi- ment ; because it was in this genus Lamarck, Sennebier, &c. noticed the striking variations of temperature recorded in the commencement of this section ; it moreover flourished in my immediate neighbourhood, and was of convenient size to esta- blish a complete series of measures upon. The plants were dug from the marsh in which they grew, with several pounds on Vegetables, with reference to their Temperature. 5 of native soil around their bulbs, shortly after sun-rise, placed in a wooden box and carried at once to the place of destina- tion about 200 yards distant ; after having been left a suffi- cient time to allow the soil to radiate any excess of heat, or about two hours under any circumstances, the measures were commenced, and recorded at the time. Other examinations of the same group of plants took place however at different periods in the day, the plants being uninjured and vigorous. It is necessary I should observe here, that all attempts made to examine plants in situ failed from various causes ; the dif- ference of temperature between parts exposed to the sun and those in the shade ; the impossibility of managing the delicate thermoscope in the open air ; the disturbing effects of cur- rents, gusts of wind, &c. ; nor does it appear to me at all necessary that such examinations should be made, even if the results could be depended upon. The measures derived from a vigorous plant removed under the foregoing circumstances are fully as trustworthy; and when the great deviations of the needles come to be considered, even the most sceptical will allow that the difference of situation would not have influenced the result beyond a few degrees ; in which I may possibly be in error ; but upon the general fact there cannot be any dis- pute. So far the tables introduced may be regarded as exhibiting the measures made upon one species ; but although it has not been considered necessary to tabulate the other results, yet a similar series of experiments were made on the undermen- tioned plants, as far as it was found practicable, but none of- fered the advantages possessed by Arum. The examination of these plants gave the same general result, and they may therefore be dismissed, after simply stating that they corroborate in all respects the observations hereafter to be made on the subject of vegetable temperature, &c. Symphytum officinale, Pastinaca sativa, Cicuta maculata, Asclepias obtusifolia et syriaca, Arctium Lappa, Sagittaria sa- gittifolia, Rumex crispus, Lobelia cardinalis, Daucus Carota, Datura Stramonium, Delphinium consolidum, Cynoglossum offi- cinale, &c. The botanist will recognise in this list, plants of sufficient bulk to allow of the introduction of the thermo-electric pair. They are also very frequently met, and were chosen partly from this cause, as well as from their proximity to the labora- tory. The list could be elongated indefinitely if a smaller pair were used, but it is unnecessary to introduce other cases, as each observer can modify his apparatus as to the fineness of the elements according to his pleasure. 6 Professor Gardner on the Influence of the Dew-point Lest the deviation of the needle of the galvanometer should be due to any other cause than a current produced by the temperature of the plants, several experiments were made to decide this point. The magnetic influence of the tinned iron, the action of vegetable acids, friction, radiation from the per- son or surrounding objects, were all examined, and it was found, that under the precautions adopted, all these disturb- ing causes were neutralized, so that all the measures given are solely attributable to the presence of sensible heat in the plant . Where more than one measure is recorded, it was either made upon different parts of the same plant, or at different times upon different parts ; in the latter case, the time which had elapsed between the measures is also recorded. Table A. June 8th, 1839. A vigorous group of Arum JValteri with well-developed spathae, and several pounds of mud in situ. Thermometer 66° Fahr. Dew-point 54>°. Drying power 12°. Clear. . Parts of the plant examined. Two hours after col- lection. Three hours after col. lection. + 14-8 + 14-8 0 - 7-15 —20-9 -20-9 -20-9 All in degrees of galvanometer. "Agreeing with the mercurial thermometer, or 3°-8 Fahr. below the at- <{ mospheric l_ temperature. Fully developed leaf stem Stem (or rather collection of pe- "] tioles)oneinch below soil with- I Stem, six inches below soil, co- \ vered with adherent earth ... / Table B. June 11th. Pastinaca sativa in flower, with adherent soil. Thermometer 81° Fahr. Dew-point 66°. Drying power 15°. Clear. Farts of the plant examined. Galvanometer. Stem, near umbel with young \ + 8- 0 0 - 1-4 -106 —20 -20 —20 + 8- 0 0 fCorrespond- 1 ing with a depression of a little more than 3-5° of < Fahrenheit's I thermometer. Stem at 3 feet, %\ feet and 1 foot \ Stem six inches above grouud... Stem one inch above ground ... Larger branches of root Temperature of the soil on Vegetables, with reference to their Temperature, 7 Table C. June 12th. Arum Walteri, a fresh group, &c. Thermo- meter 86° Fahr. Dew-point 64°. Drying power 22°. Clear. Parts of the plant examined. Galvanometer. Male & female portions of spadix 0 0 0 + 1 0 -1-4 -205 -20-5 —20-5 0 0 0 + V2 0 -1-4 -20-5 0 0 + 1-5 0 0 0 0 +1 0 "Agreeing with the thermo- metric tempera- ture of 3°-6Fahr. f below the \ air. Collection of leaf-stems (stem) Stern three inches above soil ... Bulb Soil Table D. June 7th. Arum Walteri, &c., three hours after collection. Thermometer 64° Fahr. Dew-point 51°. Drying power 13°. Fahr. Clear. Parts of the plant examined. Spadix in vigorous / male part.., action \ female part Petioles of various leaves Midribs of various leaves Stem (collection of petioles \ two inches above soil J Stem one inch above soil Stem surrounded by soil Temperature of soil , Galvanometer. + 13 + 13-7 + 8-8 + 13 + 2 - 2-5 —14 -14 + 8-8 + 12-5 14 + 7 + 12 -14 + 8 + 11 + 7 -14 ("Agreeing with the i thermo- t metric measure To these tables many others might be added, as they all tend to establish the same point. If we examine them solely to ascertain whether they afford any proof of the existence of a certain specific or vegetable heat, we are irresistibly led to acknowledge that the proof is against any such vital agent, and we deduce this, — . 1st. Because in the four tables the atmospheric tempera- tures quoted are 66°, 81°, 86° and 64° respectively, and yet the plant varies with each. 2d. We observe that the temperature of the soil is thesame as that of the subterrene stem or root, and that the excess of temperature, if any such exist, is found in parts remote from the soil, and in which vital action is taking place. It is na- tural that the root should be of the same temperature as the earth, for along its vessels are passing the fluids derived from the soil ; and the conducting power of the latter must tend to 8 Professor Gardner on the Influence of the Dew-point keep down the heat of the root, even when chemical action is taking place most actively in its structure. We are therefore justified in asserting that vegetables (so Jar as annuals and perennials) possess no specific heat similar to that belonging to mammals. Sec, but that their temperature varies 'with the atmosphere within certain limits. § 2. That 'the variations plus or minus the atmospheric tempera- ture are partly owing to the state of the dew-point, fyc. (p.l.) It is well known that evaporation cannot take place from any surface unless the temperature and dew-point differ ; for as a given bulk of air is only capable of retaining a certain amount of watery vapour in solution at a known tempera- ture, it follows, that if the dew-point indicates that amount of saturation, all evaporation must cease so long as these condi- tions are maintained. It is also well known, that the heat produced by chemical and vital actions taking place in the highest animals is antagonized by evaporation from the skin and lungs, the tendency of which is to produce coldness. We have here therefore a source of heat and its opposite which likewise exists in plants, with this difference, that whilst the former power is considerably lessened, the latter is increased in consequence of the extensive surface from which evapora- tion takes place. But the rapidity of evaporation is dependent upon several circumstances, as the amount of drying power, velocity of the wind, extent of surface, &c. ; of these the first is the most im- portant and easiest of examination. To show its influence, we introduce three other tables, selected as illustrating the influence of the amount of drying power most extensively. Table E. June 12th. Arum Walteri; soil extremely wet, and conse- quently adhering less firmly than in the previous cases. Ther- mometer 85°. Dew-point 60°. Drying power 25°. Clear. Parts of the plant examined. Galvanometer. -5 -5 -5 0 -2 0 -9 + 2 -7-5 — 24 -27 -30 -30 -5 -5 -5 0 0 0 -8- -24 -5 -3-6 -5 - -2 - -2 -7-5 —5 -5 —5 0 Spatha open and J male portion spadix active \ female Male spadix giving off pollen ... Expanded leaf, midrib Stem, or collection of petioles Stem three inches below soil ... Temperature of the soil f With I meter. on Vegetables, 'with reference to their Temperature. 9 In this table we are presented with an unusually high amount of drying power, the effect of which is to produce so rapid an evaporation, that the heat generated in the most ac- tive parts of the plant is neutralized. This group of plants, although very vigorous when examined, was drooping in six hours after from excessive evaporation. Table F. June 14th. Arum Walteri, with plenty of moist earth. Ther- mometer 86° Fahr. Dew-point 62°. Drying power 24-°. Clouds rising. Parts of the plant examined. Galvanometer. Young spadix, male portion ... -4 -4-5 -5 — 5 ' -5-5 —5 Expanded spatha {^^pa'dix midrib ... -5 -5 -6 -5 midrib -9 -6 —9 -6 Main stem one inch above soil -36 three inches below -55 -56 ... / Agreeing with the \ thermometer. Table G. The same group as in Table E, again examined six hours after collection, about half an hour after the falling of rain. Plants very vigorous. Thermometer 75° Fahr. Dew-point 65°. Drying power 10°. Clearing. — I Parts of the plant examined. Galvanometer. Young spatha, male part + 8 +8 +8-5 +8 + 10 + '5 + 12 — 2 -30 -32 +9 +7-8 + 8-8 + 9 0 + 8 + 10 ("Agreeing with •j the thermome- Lter. Young expanded leaf, midrib ... six inches below ... Temperature of soil In tables E, F and C of the previous section the drying power is extremely high, 22°, 24°, and 25° Fahr. ; the effect accord- ing to hypothesis should be an exalted evaporation, and we find accordingly that all parts of the plant in these three tables exhibit a temperature below that of the atmosphere. 10 Professor Gardner on the Influence of the Dem-point The tables G and A and D of section the first are of a dif- ferent class ; in these the drying power varies from 10° to 12° and 1 3° ; being about half of the power in the above tables, and representing the air more saturated with watery vapour, and therefore less conducive to evaporation. In these tables we remark an uniform elevation of ■ temperature in all the highly organized parts of the plant; notwithstanding the minus measures of the root from contact with a moist and therefore evaporating soil ; a good illustration, en passant, of the non- conducting nature of living vegetable tissues. Not to become diffuse, we perceive in these results, — 1st. An uniformity which recommends them to our reason. 2ndly. They are in conformity with the experience of man- kind. The effects of moist air on vegetation is known to all, the rapid growth, the vigour of plants, or to speak more scien- tifically, the activity of the chemical and organic actions which maintain life are fully manifest. The result is an increment of temperature in exact proportion to the varying activity of each organ, whether in the respiration of the leaf or the ge- nerative functions of the parts appointed to the reproduction of the species. The effects of a drought are no less apparent ; the leaves hang down ; there is an air of listlessness about plants very analogous to the effects of heat upon the human frame, and due to the undue evaporation. How firm and succulent is the state of a leaf during moist weather ; how exsiccated and flabby during a dry season ! of this the tobacco planters in Virginia are so well aware, that they esteem moist foggy weather favourable when gathering their crop. It is somewhat curious that these remarks apply to the human family ; the natives of moist countries, as the Netherlands, England, &c, being of fuller habit than those who live in arid regions ; this similitude does not however extend so far as in plants, from the effects of the diseases prevalent in swampy countries. It gives me great pleasure here to recom- mend the paper of Mr. Hopkins in the London and Edin- burgh Philosophical Magazine for February 1839, on Malaria, in which he examines the influence of the hygrometrical state of the air upon animal life. At this stage of the investigation it is necessary to meet an objection already urged against the foregoing doctrine, that it levels the principle of life in vegetables to mere chemical action. We do not hold any such view. We simply claim that the sensible caloric generated by plants is the result of internal action; the amount of caloric is also more or less, ac- cording to the activity of the evaporation, the influence of high on Vegetables, with reference to their Temperature. 11 temperature radiation, and conduction of the soil. The or- ganic molecule of plants is not a mere compound atom, for it is beyond the art of the chemist to create it synthetically. But, further, to meet objections of this kind, and convince ourselves of the influence exercised by evaporation upon the temperature of vegetable substances, we resolved to have re- course to experimental proof of a direct nature. For this purpose an experiment made by Dr. Hales (Statical Essays, exp. 30) upwards of a century ago, was repeated with such modifications as to suit our purpose. A green apple, about l± inch in diameter with a cluster of leaves, was plucked from the tree; and the stem introduced through a cork into a glass tube filled with water, to the lower end of which a smaller tube was cemented, the extremity passing downwards into a cistern of de- coction of logwood ; the appa- ratus being supported in the ver- tical position by a retort-stand, as represented in the sketch; and being found air-tight, the fol- lowing experiments were made. The temperature of the apple was estimated at given intervals with the thermo-electric pair, at the same time the drying power and elevation of the coloured fluid in the smaller tube was ex- amined, and the measures tabulated for the purpose of ex- amining the connexion of these phenomena at a coup d'ceil. A further experiment was then made by covering the apple and its leaves with a delicate caoutchouc bag, so as to arrest evaporation, and after a given interval examining the tempe- rature of the fruit and elevation of the coloured fluid. These experiments were repeated many times, but it is unnecessary to adduce more than two series in this place. Table H. June 14th. An apple with twelve leaves, examined imme- diately after collection at lh 45' p.m Examined at intervals of Height risen in interval. Galvano- meter. Temp, by Therm. Dew- point. Drying power. State of the Atmosphere. 15' 18' 15' 15' T8W inch. 9 TIT tVtt & TV 0 + -5 +3-6 + 5-5 84 F. 84 80 76 64 65 63 63 20 19 17 13 Cloudy. Very cloudy. Thunder, &c. Rain storm. 12 Professor Gardner on the Influence of the Dew-point After a delay of 12' the caoutchouc bag was used and tied tightly around the stem, and after 1 7' the bag was pierced by the electric pair, the results being, — Examined at intervals of Height risen in interval. Galvano. meter. Temp. Dew. tu y - point. Therm. * Drying power. State of the Atmosphere. 17' 6 TtT + 13-75 80 67 13 Clear. Beyond this period it is impossible to examine the gauge, for the included stem begins to give off gas into the water, and therefore partially arrests the ascent of the coloured fluid. Table I. June 15th. Experiment as before, time of collection 9h 35'. Examined at intervals of, Height risen in interval. Galvano- meter. Temp. by Therm. Dew- point. Drying power. State of the Atmosphere. j 9h35' 20' 35' 0 lVAuich. 1. 6 1 TTT -30 -2-5 — 1-6 73 72 72 53 55 57 20 17 15 Fair. Cloudy. Cloudy. The fruit and leaves were entirely covered with the caout chouc at 10h 40', and pierced after 35/ delay. 35' 7 TV + 15-0 74 59 15 Cloudy. The coldness of the fruit in the three first measures of the table I. was due to the presence of a little external moisture, and the greater temperature of the room than the external air. In both these tables the effect of arresting the evaporation is extremely apparent by an elevation of 8^° and 160,6 re- spectively ; it is to be observed, however, that the drying power given in the two additional tables represent the external and not internal measure; the saturation within the caoutchouc- bag being probably greater. In the table H. there is another coincidence worthy of remark, the gauge marks a decreasing power of suction on the part of the apple as its temperature increases and the evaporation decreases, showing a compen- sation between the amount of perspiration of the leaves and fruit and the supply of fluid. Without detaining the reader, it appears that the foregoing tables prove, — 1st. That the temperature varies with the drying power. 2ndly. That the amount of evaporation and its effects in pro- on Vegetables, with reference to their Temperature. 13 during coldness is directly as the greatness of the drying power, and inversely as the approximation of the dew-point to the at- mospheric temperature. § 3. The sensible heat of plants is directly as the atmo- spheric temperature and the chemical action going on in their cells, and inversely as the radiation, evaporation and con- duction together, tyc. (p. 1 .) We have introduced this postulate rather to give complete- ness to the subject than to enter into any lengthened examina- tion. That it is true, can be readily shown by a few references to the foregoing tables ; the proofs drawn may be conveniently ranged under three heads : — 1st. The temperature of plants varies nearly with the at- mosphere, the greatest difference measured being about 5° Fahrenheit. 2ndly. The parts in which the greatest exhibitions of tem- perature above the air have been witnessed are the seat of ac- tive chemical and organic action, as the ovaries, male spadix, midrib of leaves, &c, the stem being seldom above or below the external temperature. 3rdly. Roots and subterrene stems are of the same tempe- rature as the soil, and generally below the atmosphere, in con- sequence of evaporation taking place from the earth. This diminished temperature in the plant must depend partly upon conduction. That vegetables also lose heat by radiation, is shown by the copious deposit of dew seen upon their leaves after a clear chilly night. § 4". A review of the subject, with some remarks on apparent anomalies. Since the preceding experiments were made there has been published in the Journal de Chimie, an article on vegetable heat by M. Dutrochet*. He inclosed a dead and living plant in an atmosphere saturated with moisture, and examined their temperature with Breschet's physiological pair. The result of his experiments brought him to the conclusion, that living plants possessed a temperature that exceeded the atmo- spheric temperature by one-third centigrade as a maximum. Van Beck has since repeated the experiments of M. Dutro- chet and arrived at an opposite conclusion, viz. that the living plant betrayed two-thirds centigrade as a maximum below the dead plant. Independently of the discordance in these measures, we cannot understand how a plant can be said to possess a spe- * The author did not see the original paper, but an extract in the Edin- burgh Philosophical Journal of Professor Jameson, 1840. 14 Prof. Gardner on the Influence of the Dew-point on Vegetables. cific temperature that varies within one-third plus or minus the atmospheric temperature, which may be 90° Fahr. at noon, and 40° in the evening. The real cause of the elevation or depression measured, is to be found in the more or less per- fect saturation of the atmosphere in which the experiments were conducted. There is, however, a great difference be- tween the amount of heat measured by M. Dutrochet and myself; but whatever may be the cause of the discrepancy, the measures given in the tables are certainly free from error, since most of them were authenticated by the simultaneous examination of my friends at Hampden Sidney College. We are much more concerned by the apparent anomalies exhibited by Nature. Why are not all plants destroyed by frost? Why do not tubers, bulbs, &c. perish during winter? For if there be no specific heat in these organized substances, their fluids should freeze and thereby produce disorganiza- tion. In reply to this we remark, that the fluids of vegetables congeal at temperatures below the freezing point of water in consequence of the presence of mucilage and acids, &c. Again, the degree of succulence of the plant and strength of the tissues, as well as their non-conducting nature, must not be lost sight of. It is remarkable that all northern evergreens have more or less coriaceous leaves. The vegetation of coun- tries invaded by cold is hardier than that found in the tropics; in the former localities the majority of plants are annuals or perennials, or trees which cast their leaves ; whilst in the south evergreen trees abound which are incapable of enduring ex- posure to one frost. Our trees are often found with their sap frozen without the texture being destroyed ; and in the Annates de Chem. et de Phys., torn. xv. p. 84, there is an account of a parcel of young trees which were kept in a frozen state for twenty-one months and yet finally vegetated when gradually thawed and planted out, showing conclusively that the woody fibre resisted the disruptive force of the expanding water when in the act of freezing. The non-conducting nature of the bark and wood is another powerful protection ; we witnessed a poplar tree cut down in the depth of winter ; on the northern side of the trunk the wood was quite dry and the sap probably frozen, whilst on the southern exposure the sap was fluid : this fact proves the necessity of paying every attention to the exposure of trees which are transplanted in the winter, espe- cially evergreens. Many roots, tubers, bulbs, &c. may be exposed with appa- rent impunity during winter, but if we examine the conditions necessary to secure them, it is found that they must be either covered with soil or are naturally of a dry and amylaceous Notices of the Labours of Continental Chemists. 15 nature. The protective power of a slight covering of soil or vegetable matter is extraordinary; some potatoes were covered with about two inches of earth and others left exposed on the surface of the ground at the same spot of the garden in No- vember ; a frost occurred at night, the thermometer sinking to 28° Fahr., and it was found that all the uncovered potatoes were frozen, their cellular tissue being broken up ; whereas the buried specimens were entirely free from the action of the cold. The temperatjire of springs is worthy of notice as a proof of the non-conducting nature of the earth, whereby it is well calculated to preserve organic structures from the ef- fects of frost. These conjectures are advanced not as satisfactory argu- ments against the apparent objections detailed, but only as throwing out hints for future researches. These objections do not invalidate our measures, for they are demonstrable. The deductions may be in error, but we are content to offer the experiments as a contribution to the science of botany. D. P. G. II. Notices of the Results of the Labours of Continental Che- mists. By Messrs. W. Francis and H. Croft. [Continued from vol. xx. p. 225.] On the Oils of Fennel, Anise, and Star-anise (Illicium anisatum). ]\/T CAHOURS has examined the stearopten of these three -r A • oils, and has found them to be perfectly identical ; the substance used for the experiments was generally made from the oil of anise, because from this oil it can be obtained in larger quantities than from either of the others. The solid oil can be very easily obtained pure by expression and cry- stallization in alcohol. It crystallizes in white shining leaves. Its specific gravity is nearly equal to that of water. It is pul- verisable at 0°, melts at 18° C, and boils at 222°. On being converted into vapour it appears to suffer some change, so that the observed density of the vapour does not agree with that calculated from the formula. In a solid state it is not changed by exposure to the air, but if kept fluid for a length of time it is converted into a resin ; chlorine and bromine act violently on it; alkalies have no action except when employed in the manner proposed by Dumas and Stass, in which case an acid product is obtained. Strong acids, as the sulphuric, phosphoric acids, &c, change it into an isomeric body. The atomic weight of the solid anise oil was determined by mea- suring the quantity of hydrochloric acid absorbed by it The formula is C20 H24 O2. 16 Notices of the Labours of Continental Chemists. Bromide of anisal {BromanisaT). — Bromine acts violently on the solid oil, hydrobromic acid is evolved ; on allowing the fluid mass to stand for some time it partly solidifies ; small portions of aether extract an oil which contains bromine, and the solid substance may be purified by solution in boiling aether and pressing between bibulous paper. It is colourless, forms voluminous crystals, insoluble in water, somewhat soluble in alcohol, and more so in aether. It is decomposed at a tempera- ture above 100°. Formula is C20 H18 Br6' O2. The action of chlorine is more complex ; according to the length of time the chlorine has acted different products are formed, none of which crystallize, and whose purity therefore cannot be relied on. Once a substance was obtained with the formula C20 H18 CI6' O2. The next product is C20 H15 CP O2. Both bodies are decomposed by distillation. Sulphuric and phosphoric acids and some anhydrous chlo- rides, as those of tin and antimony, convert the solid oil into a white crystalline substance, soluble in sulphuric acid with a red colour ; it has exactly the same composition as the solid oil, viz. C20 H24 O2; Cahours calls it Anisoin. By the action of nitric acid of 23-24-° Beaume a new cry- stallizable acid is obtained, which has been mentioned in one of our former reports. Anisic acid. — The rough impure acid may be dissolved in ammonia, the salt recrystallized several times, and from the insoluble lead salt the pure acid may be obtained. The acid crystallizes in long needles, sparingly soluble in cold water, but much more so in boiling water ; easily soluble in alcohol and aether. It can be volatilized without decomposition, and forms soluble salts with the alkalies and earths. The lead and silver salts are soluble in hot water. The acid precipitates sesquioxide of iron, like benzoic and cinnamic acids. Formula is C16 H14 O6. The aether may be prepared by passing hydrochloric acid into an alcoholic solution of anisic acid. By heating- anisic acid with an excess of baryta a fluid sub- stance, anisoX is obtained similar to Mitscherlich's benzin, in- asmuch as it seems to form analogous compounds ; it differs, however, in so far that it contains oxygen, its formula being C14 H14 O2. Note.— [The confusion in chemical nomenclature seems nearly to have reached a climax. Berzelius has proposed some excellent rules for the terminations of names, but they have unfortunately been but little attended to. Mitscherlich's discovery of benzin paved the way to that of many similar sub- stances. He called this substance, C12 H12 benzin. Liebig Action of Chromic Acid on Volatile Oils. 1 7 calls it benzol. A similar substance obtained by Gerhardt and Cahours from cinnamicacid, C16H16, is called cinnamen, that from cuminic acid, cumen. Simoux and Marchand call cin- namen cinnamomin. Cahours calls the above substance anisol, it being prepared exactly like benzol (benzin). — H. C] Anisonitric acid is formed by boiling the anise oil with strong nitric acid until the oily substance first produced is redis- solved. The acid solution is precipitated by water and the substance well washed, dissolved in ammonia and its salt cry- stallized several times, out of it the pure acid may be obtained. It is yellowish white, not very soluble even in warm water, and crystallizes out of its hot solution in small acicular crystals, tolerably soluble in alcohol. Forms insoluble salts with lead and silver. It cannot be sublimed unchanged. Formula for the free acid C16 H12 N2 O10; one atom of water is driven out when it is combined with oxide of silver, the formula of that salt being C16 H10 N209, Ag O (the crystallized aether of this acid has been noticed by Mitscherlich). By the action of fuming nitric acid on the solid anise oil a resinous substance is obtained, nitranisid; its probable formula is C20 H20 N4 O10 (?). Treated with caustic alkalies it evolves ammonia and is con- verted into melasinic acid. Oil of bitter fennel (fenonilamer) appears to consist of two oils, one solid having the same com/- position as that of anise-oil, and a volatile one having the same constitution as the oil of lemon and turpentine. If a stream of binoxide of nitrogen be passed into this latter oil, it becomes thick and opake,and alcohol of 0*80 causes a white silky precipitate which must be washed with alcohol. By a gentle heat this substance becomes yellow and is easily de- composed. Somewhat soluble in absolute alcohol, more so in aether, soluble in concentrated solution of alkali, and is preci- pitated again by acids. Formula C15 H24 N4 O4. — {Annales de Chem. ft de Phys., Juillet 1841, p. 274.) Action of Chromic Acid on several Volatile Oils. Persoz has examined the products obtained by treating aethereal oils with a mixture of bichromate of potash, sul- phuric acid and water. From the oils of anise, star-anise (anise etoilee) and fennel, acetic acid and an insoluble pro- duct consisting of two acids, were produced. These acids Persoz calls Umbellic and Badianic acids. The umbellic acid is little soluble in cold water, more in hot, soluble in alcohol, very little in aether; and can thus be separated from badianic acid ; with concentrated nitric acid it forms an acid similar to the cinnamonitric. In its salts it resembles the benzoates. It melts at 1 75° or 1 80° C, boils at 275° to 280°. [This umbellic Phil. Mag. S. 3. Vol. 21. No. 135. July 1842. C 18 Notices of the Labours of Continental Chemists. acid seems to differ from the anisic solely in being insoluble in aether;, it would be worth while to examine this point further. Both acids are formed equally well outof all three oils. — H. C] Badianic acid is more soluble in water. By the action of chromic acid on Roman carraway oil, Persoz obtained two acids, cyminic and cumino-cyminic. The former melts at 115°; it is tasteless, little soluble in cold water, easily in alcohol and aether. The latter is insoluble in all three liquids. It is not decomposed by boiling with strong sulphuric acid. From some other oils new acids have been obtained, but as both they and those above have not yet been fully described, it will be better to defer any further report upon them for the present. Oil of cinnamon gives acetic and benzoic acids, and according to Marchand a considerable quantity of hydruret of benzoyl. It must be remarked that in these reactions acetic acid is always formed. — (Comptes Rendus, torn. xiii. No. 8. p. 433.) Action of Hydrate of Potassa on Hydrobenzamid. Rochleder finds the formula for hydrobenzamid to be C21 H18 N2; when fused with the hydrate it becomes yellow, at last black, and ammonia is evolved ; the residual mass is washed with water. The washed powder is yellow, fusible at a gentle heat, decomposed at a higher temperature, partly soluble in alcohol and aether: it consists of three bodies; the first is found in small quantities at the commencement of the operation ; it is a yellow oil soluble in alcohol, but has not been further examined : the second is soluble in alcohol, white and crystalline ; the author calls itbenzostilbin : the third, benzolon, is also white and crystalline, but insoluble in alcohol ; it is formed during the latter part of the operation. Benzostilbin when freed from oil is not very soluble in al- cohol, soluble in aether, by means of which it can be obtained in large crystals. Melts at 244'5° C, and at a higher temperature sublimes, but not unchanged ; soluble in concentrated sul- phuric acid with blood-red colour. Not decomposed by boiling with caustic potassa. Formula C31 H22 O2. Benzolon is purified by solution in warm sulphuric acid and precipitation out of the red solution by alcohol. It is crystalline, insoluble in water and alcohol, melts at 248° C, sublimes almost unchanged. Decomposed by fuming nitric acid. Formula C11 H8 O1, or benzon minus benzin (benzol.) — {Ann. der Chem. und Pharm., vol. xli. p. 89.) On the Salts q/Uvic (Racemic) Acid. Uvic acid is monobasic according to Fresenius, and this is its principal point of difference from tartaric acid. In the Salts of Uvic Acid. — Nicotin. 19 crystallized state it contains two atoms of water; only one can be driven out by heat, the other is basic. The neutral salts of the alkalies are easily soluble and crystalline, form acid salts, but the fixed alkalies do not form together double salts. The salts of the alkaline earths are difficultly soluble, form no double salts, but this is found to be the case with those salts of the magnesian series which contain halhydrate water. Ammonia salt ... Uv + N2 H8 O. _ Acid salt Uv. N2 H8 0 + Uv. H2 O. Potassa salt UvKO-f-2aq. ("Compounds similar to Acidsalt £Kt du dy p du *~dz> es?)'- dx .fc, dv dv r dz> kit) = ■Kird'W M5S + dy vdw Professor Kelland's Note on Fluid Motion. 31 or W7/ = M du dy du dz dv p (Ijw dx da? T^rdv -ndw xt dv dy' dw^ d~z; (2.) where dz xt div dx dm d? du Tz' dv (S*.) p=:= *» f/j/ dx' 1. One way of satisfying all the equations is by supposing M = 0, N =b, P = 0 ; in which case the equations (3.) in- dicate that udx + vdy -\- wdz is a complete differential. 2. Another way is to suppose M, N and P all absolutely constant; in which case the velocities u, v, w will be deter- mined by the same equation, viz. by either of the equations (1.). Hence it, v, w all have the same form. Also the equations (2.) give M^ + N* dx dx dx dv -ndw 0, &c. &c, orMa+ Nu+ Pwisa quantity whose partial dif- ferential coefficients, with respect to each of the coordinates, is zero. This quantity is therefore either zero, or a function of t only. a. If it be zero, udx + vdy + ivdz is integrable by a factor, for the equation M?i + N»+Pro = 0 is the well- known equation of condition that this may be the case. b. IfMtt+Nu + Ptt> —f{t), udx + vdy + wdz is not a complete differential after being multiplied by a factor. The equations are nevertheless integrable in this case, and give as their result, u= F(Mz-P#, N*-Py, /), t> = (Mz -P#, Ns-Pj/, t), * See ray Memoir on the Theory of Waves, Trans. Roy. Soc. Edin., vol. xv. p. 116. 32 Professor Kelland's Note on Fluid Motion. the functions being subject to the condition MF+N4> + P^ ■=/('). 3. If M, N, P are explicit functions of t only, our equations (1.) are reduced to *M M^ + N^ + pi", at dx ay a z ^= M^ + N^+P^, at ax ay dz d P ^ifdw ^dw , „- -4 c/ + 2c e Ve*- -4 c/ 2c Insert these values in the former of the equations marked (7.): then there results as the value of X2 Yx . T)x D2, ed- Vtf*-*qf)(e*^icf) (7.) Wi2- 2/ X\V\ + cx^—dy —exx +/}*2y2. 40 Mr. T. S. Davies on Pascal's Mystic Hexagram. But as xx yx is a point in the conic section denoted by (1.), we have ay? + ex? — dyx — e xx +/= — bxxyx, which substituted in the preceding expression gives us Again, since Xj Y2 is the same function of (70 *2yi- (*i -7) (y2-8). Also, since (^j yx) is in (1.), and (ar8 y^ in (2.), we have the equations, /3yi = ^x + /38 (8.) yy2 = «.r2-ay (9.) In' the values of X15 X2 substitute the values ofyx, y2 from (8.) and (9.), and in those of Yx, Y2 those of xv x^ from the 42 Mr. Balmain's New Process for preparing Oxygen, same equations ; and denote, as before, the denominators by Dj and D2 respectively : then v _ * (ft + 7) *i ** v _/3(* + g)ytyn > . . (10.) Substitute these in the expression X2 Yl — Xj Y2, and we have X^-X^ _ (« + 8)Q3 + y)jfly1.jr8ya _ Q8 + y) (« + 8) g8y8.gi.y» DiD2 D.D, = 0, which is again the ordinary criterion of G H passing through the origin, O. Royal Military Academy, May Uh, 1842. IX. New Process for Preparing Oxygen By W. H. Balmain, Esq. To the Editors of the Philosophical Magazine and Journal. Gentlemen, /"^XYGEN being much in request for the oxyhydrogen ^•f blow-pipe, and indeed for purposes of illumination, it is important to have an expeditious and cheap process for preparing it. Moreover, in the present day, when practical chemistry is becoming so popular, it will, independently of all matter of expense, be no insignificant acquisition to the lecturer and juvenile experimentalist to have a ready method of preparing the principal supporter of combustion. It has occurred to me that it may be prepared from bichromate of potash by the action of sulphuric acid; and as the process has upon trial proved successful, I beg leave to suggest it to those whom it may concern through the medium of your Journal. A mixture of three parts of bichromate of potash and four parts of common sulphuric acid contained in a capacious re- tort, will, on the application of a moderate heat, yield pure oxygen with a rapidity entirely at the command of the ope- rator. K Chr2 . S4 H4 nrnAl„a K SandChr, 03+ S, 47-5+104= 151-5 ana 160+36=196 Proauce 47'5+40+ 56 +24+120 = 287'5and36and24' Mr. Drach on the Hourly Observations at Leith in 1824-25. 43 This process is cheaper than that of heating chlorate of potash ; for two parts of bichromate of potash will produce as much oxygen as one of chlorate of potash, while the latter is nearly three times the price of the former; and besides this, the residue of the first is valuable, and may be reconverted into bichromate of potash. It is likewise a more convenient process than any at present known, since it may be conducted at so low a temperature that an ordinary retort and lamp may be used for the production of a considerable quantity of oxygen. Mechanics' Institution, W. H. BALMAIN. Liverpool, May 10, 1842. [Note. — I have tried this process and find that it answers very well, the gas being given off, I think, with greater readi- ness than when sulphuric acid and binoxide of manganese are employed. Occasions I have no doubt will occur in which this method may be advantageously substituted for others. — R. P.] X. On Sir D. Brewster's Deductions from the Hourly Ob- servations at Leith in 1824-25. By S. M. Drach, Esq., F.R.A.S. To the Editors of the Philosophical Magazine and Journal. Gentlemen, HPHE deductions alluded to in the title of this article, as -■- detailed in the Edinburgh Philosophical Transactions, vol. x., flow from any expression of the temperature in func- tions of the time. Let v = the temperature, / = the time ; — T = a fixed instant ; then to be real v = function of J.f+T\\ (' + T)\ log (t + T), *™ i (t + T), constant \, which is developable into the series r; = A+B(* + T) + C (t + T)2 + D(* + T)3 + &c. A, B, C, &c. are functions independent of the time, and com- prehending the latitude, declination, radiation, &c. When t = - T, v = A. First. If A = the daily mean temperature, t = — T = time of morning mean, and 0 = B + C {t + T) + D (t + T)2, + &c. gives the other times of mean daily temperature. There being only one (evening) mean, this series must be very convergent, and B B t — — T — j^t or more correctly, t = — T ~ ; thus B D is very much less than C2. c-c-D 44 Mr. Drach on Sir D. Brewster's Deductions Secondly. For the maximum and minimum times : ^ = 0=B + 2C(*+T)+3D(* + T)2, ,_ t C . /C2-3BD. * l~~ L ~3D+V WW~~ ' the first corresponds to a minimum, the second to a maximum ; the former being nearer than the latter to the morning mean. Thirdly. If A, T be the temperature and epoch, and t not great, » = (A + ^^T2) + (B++32DCTf)^(^ + 3DT)^ + D.^ is the equation for some time on each side of T ; neglecting the small quantity D t3, it is that of a parabola, having v for an absciss and t for an ordinate. Fourthly. Beginning at noon, T = 0, tt=A + Btf+C*2 + D tf3 + &c. Taking the mean of homonymous hours (the unit of t being one day), that is, taking the mean of t + £ and t — i» we obtain „,+# = A + B(< + i) + c(^ + i- + l) + &c. = A + T + Te + (B + t) ' + C'2 + &c- rj Whereof the mean = A + — + B t + C t* &c. For the 16 mean of the twenty-four hours, we add — t and + t, there- fore 24A 2C 12* f8 2E 12< f* General mean = _ + _ 2^ _2 + — . 2^ . ^ 650 C 60810 E A , C | Q = A + 12^576 + 18757? = A + H + &C* Now C, D, &c. being small, it is evident this nearly agrees with the homonymous mean, the chief error B*+ C( — — TT = p^ ) indicating very nearly a progressively uniform error, so that 5 1 by combining t and — t this error = — — C = — C must very nearly vanish. from the Hourly Observations at Leith in 1824-25. 45 These extremely general theoretical results are amply con- firmed by the above-mentioned observations. London, December 8, 1841. S. M. D. APPENDIX. These Leith observations give the temperature at P.M. lhr = 51-149 51-470 51-532 51-239 50-872 50-294 P.M. 7hr 8 9 10 11 12 49-544 48*624 47-829 47*276 46-803 46-398 A.M. lhr = 46-134 45-933 45-689 45-449 45-394 45-653 A.M. 7hr 8 9 10 11 12 The sums of the homonymous hours are — p.m. and a.m. 1 hr = 97-283 97*403 97-221 96-688 96-266 95-947 p.m. and a.m. 7 hr = 95-827 8 9 10 11 12 95-653 95-888 96-288 96-753 97-175 Sums. 193-110 193-056 193-109 192-976 193-019 193-122 46-283 47*029 48-055 49-012 49-950 50-777 Diff. + 1-456 + 1-750 + 1-333 + 0-400 — 0-487 — 1-228 The near agreement in the third column shows the series 'expressing the daily temperature to be very nearly a periodic one, and of the form A=H + Asin*+# cos t + B sin 2 t + b cos 2 t + C sin 3 * + c cos 3 / + E sin 4 t + e cos 4 t ; h, H, &c. being thermometric degrees, and t the time. Hence, as in my paper on the Plymouth barometric oscil- lations*, we can deduce the rule, that if the thermometer be observed only four times a day, at intervals of six hours, com- mencing at any time, the resulting average is all but equal to that deducible from twenty-four hourly observations. The greatest difference is here 48°-266 (mean) — I (l92°-976) = 0°*022 = one forty -Jifth of a degree of Fahrenheit. The differences of the homonymous hours (p.m. — a.m.) are lhr= +5-015 4 hr =+ 5*795 |7hr=+ 3-161 10hr= — 1-736 2 +5-537 5 +5-478 8 +1*595 11 —3*147 3 +5-843 6 +4-641 1 9 — 0'226 12 —4-379 Whence by a process exactly similar to the one in the paper above alluded to, there results temp, from noon =A = 48°-266 + 2°*1437 sin* + 2°- 1354 cos* + 0-295 sin 2 t + 0-308 cos 2 t — 0*1302 * Phil. Mag., June 1842 (Third Series, vol. xx. p. 477). 46 Mr. Earnshaw on the Motion of Luminous Waves. i sin 3^+ 0'00115cos3£— 0'00715sin4£ + 0-00686 cos 4£, temp, froml = 48o.266 + 3o.0257sin^ + 44o53f) + 0o.4265 noon = h J v ' sin (2 * + 46° 14') + 0° '1302 sin (3 t + 1 79° 30') + 0*0099 sin (4 t + 1 36° 50'). The quantities c, E, and e are the only ones wherein the separate values in each combination disagree, but this is not very material, owing to the smallness of these quantities. London, April 29, 1842. S. M. D. XL On the Motion of Luminous Waves in an Elastic Me- dium, consisting of a system of detached particles, separated by finite intervals. By S. Earnshaw, M.A. of St. John's College, Cambridge. THE equations obtained at the close of my last communi- cation on this subject (vol. xx. p. 373) involve six co- efficients, A, B, C, D, E, F. From the peculiar manner in which they enter those equations it is known, that if the co- ordinate axes be turned through proper angles, their directions still remaining rectangular, the equations will assume the forms d?z=-k*Sj, 4Sm~'&:» d^^-lcit These show that vibrations of m parallel to any one of the axes of dynamical symmetry cannot be affected by vibrations which are parallel to the other axes. Simple as these equa- tions are, they have precisely the same degree of generality as the original ones, for the motion of the particle m. It might not happen that the axes of dynamical symmetry for every particle would be parallel to those for m, and that the same position of the coordinate axes would reduce the equations of motion for the other particles of the medium to the same form, and cause them to have the same coefficients as for m. A condition equivalent to mechanical homogeneity of the me- dium must be fulfilled that this may be the case. It is neces- sary therefore to appeal to experiment for license in this matter. By experimental means we learn that the positions of the axes of elasticity for waves of a given length are fixed, and that the velocity of transmission of such waves is uniform, and that both these properties are independent of the thick- ness of the medium : hence we may assume that fcl £2 k3 have constant values through the whole interior of a medium, and that the equations in the simple forms above given are appli- licable to, and fully represent all the properties of, the trans- Mr. Earnshaw on the Motion of Luminous Waves. 47 mission of waves of light through a luminiferous medium. It is necessary also to observe that the quantities kx &2 k3 are all possible, and finite ; for were one of them otherwise, vibra- tions parallel to the corresponding axis of symmetry could in no case be transmitted ; but as no media having this property have been yet found, we are permitted to assume that the law of molecular force and the mode of arrangement of the parti- cles are such as to make kx &2 k3 possible in all cases. We are now at liberty, without affecting the generality of our in- vestigations, to suppose that the axes of symmetry were the coordinate axes employed in my former paper ; in which case D = E ==• F m 0, and the equations of motion are ^=-2S(Arsin^).£, ^=-2£(Brsin^).,,, ^r=-2s(Crsin^^).?; wherefore if w t/ o" be the velocities of transmission of vibra- tions which are parallel to the axes of symmetry, and if A be the length of the wave, then «"(t)'-*(B^). «-e)'-*(*"2)- The right-hand members of these equations involve A im- plicitly} in a manner which depends upon the arrangement of the molecules of the aether and the law of molecular force ; and thus a relation is established between the length of a wave and the velocity of its transmission ; but unhappily the ex- pressions are of such a nature as to imply that there is di- spersion in vacuo. The case therefore stands thus : dispersion in a refracting medium cannot be accounted for on the finite-in- terval theory unless there be also dispersion in vacuo. Now as there is no dispersion in vacuo, I infer generally, that the finite-interval theory cannot account for dispersion. Again, by referring to my former communication, it will be seen that the equations of motion do not depend upon the position of the front of the waves traversing the me- 48 Mr. Earnshaw on the Motion of Luminous Waves. dium *. They show that a particle may vibrate in any di- rection, and that the vibrations have no necessary reference to the direction of transmission. And it is to be kept in mind that we have found our equations without the aid of any hypothesis respecting arrangement ; and therefore it is impossible by means of arrangement to affect our results. And, again, we have assumed no particular law as the law of molecular action. I have elsewhere shown that there are laws under which the motion of the aethereal particles would not be a vibratory but a translatory motion : we have rejected these laws in assuming that k1 h2 k3 are all possi- ble : but of all the laws which would give vibratory motions and satisfy the known conditions of transmission we have re- jected none : all possible cases are therefore included in our results. I consider it therefore as proved incontestably, that according to the finite-interval theory there can be no con- nexion between the directions of the vibrations and the law of molecular force. Hence, then, the transversality of vibrations never can be established on that theory, and is therefore op- posed to it. Perhaps it is proper to remark here, that I have not taken account of the direct action of matter upon the aether; but as my results are independent of arrangement, it is ob- vious that the indirect effect of matter is included in them. Consequently the indirect effect of matter never can assist us in accounting either for the transversality of vibrations or for dispersion. If, therefore, these facts are to be accounted for, we must look to the direct action of matter on the aether. These are some of the results which I proposed to lay before your readers in commencing these papers. They clear away a great deal of mist from the finite-interval theory, and point out the only direction in which we can look for success. Mr. O'Brien has proceeded in that direction, and has announced that in that quarter " the hypothesis of finite intervals cannot be correct ;" if he succeed in establishing that position, and I doubt not he will, the finite-interval theory may be laid aside, and mathematicians will then be at liberty to pursue a more promising hypothesis. In the first of my papers I gave my reasons for thinking that those persons have fallen into error who suppose that the theory in question has accounted for * For &i k'2 £3 are absolutely constant for a given value of * ; and by transposing the coordinate axes back again from the axes of dynamical symmetry to their original positions, we shall of course obtain the equa- tions exhibited in that communication : and by the nature of this process, the constants (i. e. A, B, C, D, E, F) will involve only kx £2 ks and the an- gles of transposition : they are therefore independent of the position of the waves' front. Mr. Earnshaw on the Motion of Luminous Waves. 49 the experimental dispersion of light. The only reference to that communication which I have yet seen, is in the postscript of Professor Kelland's letter in your Journal of the present month, where, after admitting that all the values of q given in his memoir on Dispersion are erroneous, the Professo states that the error is of no importance, seeing that the fo nulse are of necessity capable of fulfilling the conditions requinted.of them. This must be admitted, I think, to be ratfcer an un- usual mode of disposing of a matter of such importance as the numerical verification of his theory. Am 1 to understand him to say, that his formulae are of necessity capable of pro- ducing correct results even if the data employed be erroneous? May I not then ask, what is the nature of the connexion of these formulae with theory ? and in what degree is his theory supported and strengthened by coincidences obtained from such formulae ? I take it for granted that the results were consi- dered as strengthening the theory in some way, else why have they been published both in Professor Kelland's me- moir and in other places in connexion with theory ? Now I showed, and Professor Kelland has now allowed, that funda- mental errors were made in the application of the data ; and the results thus obtained were announced as proofs of the soundness of the theory. I wish to ask, then, how the results could have any power at all in confirming the theory, if the formulae were of necessity capable of producing correct results from correct or incorrect data indifferently ? I am aware that the position which I have taken in the present paper touching the transversality of vibrations is al- ready by anticipation controverted in Professor Kelland's letter to Mr. O'Brien (p. 377), where we read, that "if the law " of molecular force " be that of the inverse square of the distance the vibrations are transversal only." I regret that the necessity of defending my own investigations from implied error prevents me from letting this statement pass without comment. I have turned to the part of the memoir to which the Professor has directed attention, and shall here state in as few words as possible the objections which seem to me to lie against the conclusion there come to ; merely pre- mising, that if I have misunderstood the nature of the reason- ing, 1 am open to correction. My objections are 1st. I find it stated that "v and o" are possible and equal, but o' impossible and of a different magnitude ;" and thence it is inferred that " attractive forces give rise to transversal vibrations only." Now it appears to me that, admitting the former part of this to be true, there is some error in the in- ference. For since y v' v" are the velocities of the wave, and Phil. Mag. S. 3. Vol. 21. No. 135. July 1842. E 50 Royal Society. not of the particles, the inference should have been, that there is one direction in which waves cannot he transmitted ; or, in other words, that the (Ether is opake in one direction. 2nd. But I am unable to discover on what ground it is stated that v' is impossible. I see no reason why we may not say with equal truth that u' is possible, and v and v" impossi- ble; in which case ihe inference is, that the (Ether is trans- parent in one direction only. 3rd. After all, it appears to me that the implied impossi- bility of some one (or two, as the case may be) of the quantities u u' v" has reference to a fact distinct from either of these in- ferences, viz. the instability of the medium when the forces vary according to the Newtonian law. If u' be impossible, as is asserted in the memoir referred to, it shows that the sines and cosines of all angles in which v' occurs ought to have been written in the form of exponentials, and that some equation has been integrated by sines or cosines which ought to have been integrated by exponentials. Hence it follows that a vibrating motion of the particles is impossible, and that the particles of the whole medium are in a state of either neuter equilibrium, or unstable. In either case it is unfit for the transmission of light, and results derived from it are, if at all, only accidentally applicable to the phsenomena of nature. Cambridge, May 3, 1842. XII. Proceedings of Learned Societies. ROYAL SOCIETY. [Continued from vol. xx. p. 512.] March 17, r|^HE reading of a paper, entitled " Contributions to 1842. ■*■ the Chemical History of the Compounds of Palla- dium and Platinum," by Robert Kane, M.D., M.R.I.A., communi- cated by Francis Baily, Esq., V.P.R.S., was resumed and concluded. The author states it to be his object, in this and in some subse- quent papers, to examine specially the composition and properties of the compounds of palladium, platinum, and gold ; and to ascertain how far they agree, and in what they differ, as to the laws of com- bination to which these compounds are subjected. He commences with the investigation of the compounds of palladium, employing for that purpose a portion of that metal with which he was furnished by the Royal Society out of the quantity bequeathed to the Society by the late Dr. Wollaston. He describes the mode of obtaining the protoxide of palladium, and enters into the analysis of the hydrated oxide, the black suboxide, and the true basic carbonate of that metal ; detailing their properties and the formulae which express their mode of composition. The chlorides of palladium form the next subject of inquiry ; and the author concludes from his experiments that the loss of chlorine which the protochloride undergoes, when kept for some "Royal Society. 51 time in a state of fusion at a red heat, is perfectly definite ; and also that the loss represents one half of the chlorine which the salt con- tains. But in the double salts formed by the protochloride of pal- ladium with the chlorides of the alkaline metals, he finds that the similarity of constitution usually occurring between the compounds of ammonium and potassium is violated. From his analysis of the oxychloride of palladium the author concludes that it is quite ana- logous to the ordinary oxychloride of copper. He then examines a variety of products derived from the action of a solution of caustic potash on solutions of ammonia-chlorides of potassium. Their properties he finds to indicate analogies between palladium and other metals, whose laws of combination are better known. The sulphate, the ammonia-sulphates, the nitrates, and the ammonia-ni- trates of palladium, and lastly, the double oxalate of palladium and ammonium, are, in like manner, subjected to examination in a de- tailed series of experiments. The second section of the paper relates to the compounds of pla- tinum, and comprehends researches on the composition of the proto- chloride of platinum ; on the action of ammonia on biniodide of pla- tinum ; and on the action of ammonia on the perchloride of plati- num; in which the properties of these substances are detailed and the formulae expressing their composition deduced. There was also read, "Magnetic Observations made at Prague for September 1841." ByC.Kreil. Communicated by S. Hunter Christie, Esq., M.A., Sec. R.S. April 7. — The following papers were read, viz. — Meteorological Observations, taken in conformity with the Re- port drawn up by the Committee of Physics, including Meteorology, for the guidance of the Antarctic Expedition, as also for the fixed Magnetic Observatories, transmitted to the Society by the Lords Commissioners of the Admiralty and the Master-General of the Ord- nance, and communicated by the Council, were read ; viz. — 1. " Meteorological Observations taken on board H.M. Ship Ere- bus, for August and September 1841." By Capt. James Clark Ross, R.N., F.R.S., Commander of the Expedition. {Forms 1 and 2.) 2. " Meteorological Observations taken by the Niger Expedition, for May, June and July 1841." 3. " Meteorological Observations taken at the Magnetic Observa- tory, Ross-Bank, Van Diemen's Land, for November and December 1840, and January, February and March 1841." {Forms 1 and 2.) 4. " Meteorological Observations taken at the Magnetic Observa- tory, Cape of Good Hope, for October and November 1841." By F. Eardley Wilmot, Esq., Lieut, in the Royal Artillery. {Forms 1 and 2.) 5. " Meteorological Observations taken at the Magnetic Observa- tory, Toronto, for January, February, March, April and May 1841." By C. W. Younghusband, Esq., Lieut, in the Royal Artillery. {Forms 1 and 2.) 6. " Of the ultimate distribution of the Air-passages, and of the modes of formation of the Air-cells of the Lungs." By William Addi- E2 52 Royal Society. son, Esq., F.L.S., Surgeon, Great Malvern. Communicated by R. B. Todd, M.D., F.R.S. After reciting the various opinions which have prevailed among anatomists regarding the manner in which the bronchial tubes ter- minate, whether, as some suppose, by cells having free communica- tion with one another, or, as others maintain, by distinct and sepa- rate cells having no such intercommunication, the author states that having been engaged in investigating, with the aid of the micro- scope, the seat and nature of pulmonary tubercles, he could never discover, in the course of his inquiry, any tubes ending in a cul-de- sac ; but, on the contrary, always saw, in every section that he made, air-cells communicating with each other. He concludes from his experiments and observations, that the bronchial tubes, after dividing dichotomously into a multitude of minute branches, which pursue their course in the cellular interstices of the lobules, terminate, in their interior, in branched air-passages, and in air-cells which freely communicate with one another, and have a closed termination at the boundary of the lobule. The apertures by which these air-cells open into one another are termed by the author lobular passages : but he states that the air-cells have not an indiscriminate or general inter- communication throughout the interior of a lobule, and that no ana- stomoses occur between the interlobular ramifications of the bron- chiae themselves ; each branch pursuing its own independent course to its termination in a closed extremity. Several drawings of the microscopical appearances of injected portions of the lungs accom- pany this paper. April 14. — A paper was read, entitled, " Remarks on the probable natural causes of the Epidemic Influenza as experienced at Hull in the year 1833 ; with a delineation of the Curves of the maximum, the mean, and the minimum Temperatures in the shade, and the maximum Temperature in the sun's rays at Hull, during the years 1823 and 1833." By G. H. Fielding, M.D. Communicated by the Rev. Wm. Buckland^ D.D., F.R.S. The meteorological causes to which the author ascribes the sudden accession of the influenza at Hull, and its continuance from the 26th of April to the 28th of May 1833, are, first, the unusually cold weather during March, and also the cold and wet which prevailed during April in the same year : secondly, the sudden rise of tem- perature, amounting to 21 of Fahr., which occurred in a few hours on the 26th of April : and thirdly, the continuance, through May, of extreme vicissitudes of temperature between the day and the night ; the burning heat of the days and the cold thick fogs, with easterly winds, commencing generally about sunset, and prevailing during the night. A paper was also read, entitled, " Report of a remarkable appear- ance of the Aurora Borealis below the Clouds." By the Rev. James Farquharson, LL.D., F.R.S., Minister of Alford. The phenomenon recorded in this paper occurred on the night of the 24th of February 1842, when a remarkable aurora borealis was seen by the author apparently situated between himself and lofty Royal Society. 53 stratus clouds, which extended in long parallel belts with narrow intervals of clear sky in a direction from north-west to south-east. The author gives, in detail, the particulars of his observations*. April 21. — The following papers were read : — 1. " On the Organic Tissues in the bony structure of the Coral- lidae." By J. S. Bowerbank, Esq. Communicated by Thomas Bell, Esq., F.R.S., was in part read. " Papers from the several Magnetic Observatories established in India, addressed to the Secretary of the Royal Society, by direction of the Honourable East India Company." Communicated by P. M. Roget, M.D., Sec. R.S. 1. From the Magnetic Observatory at Madras: — Magnetic and Meteorological Observations for October, Novem- ber and December 1841; as also for January 1842. Term-day Observations for October and November, and Curves for August, September, October and November 1841. Observations of the Direction and Force of the Wind, and the state of the Sky, during October and November 1841. Extraordinary Magnetic Curves for September, October and De- cember 1841. 2. From the Magnetic Observatory at Singapore : — Magnetic Observations from March to October 1841, with Curves for the same period. Anemometer Curves for March, April, May, June, July, August, September and October 1841. Abstracts of the Weather for June, July, August and September 1841; as also the Determination of the Temperature at Singapore. Tide Reports for April, May and June 1841. 3. From the Magnetic Observatory at Simla: — Abstracts of Magnetic and Meteorological Observations for No- vember and December 1841. Magnetic Observations for February, May, October and Decem- ber 1841, with Curves for the same period. April 28. — A paper, entitled, "On the Organic Tissues in the bony structure of the Corallidae." By J. S. Bowerbank, Esq., F.G.S., com- municated by Thomas Bell, Esq. F.R.S., was resumed and concluded. The author submitted small portions of nearly seventy species of bony corals to the action of diluted nitric acid, and thus obtained their animal tissue, freed from calcareous matter, and floating on the surface of the fluid in the form of a delicate flocculent mass. By the aid of the microscope, this mass was found to be pervaded by a complex reticulated vascular tissue, presenting numerous rami- fications and anastomoses, with lateral branches terminating in closed extremities. There were also found, interspersed among these, another set of tubes, of larger diameter than the former, and provided, in many places, with valves ; the branches from these larger vessels occasionally terminate in ovoid bodies, having the appearance of gemmules or incipient polypes. In other cases, masses of still larger size, of a more spherical shape, and of a [* A notice of a former paper on the Aurora by Mr. Farquharson will be found in Phil. Mag., Second Series, vol. v. p. 304.— Edit.] 54 Royal Society. brown colour, were observed attached to the membrane, and con- nected with each other by a beautiful network of moniliform fibres. Numerous siliceous spicula, pointed at both extremities and exceed- ingly minute, were discovered in the membranous structure of se- veral corals ; and also other spicula of larger size, terminated at one extremity in a point, and at the other in a spherical, head ; a form bearing a striking resemblance to that of a common brass pin. Besides these spicula, the author noticed in these membranous tis- sues a vast number of minute bodies, which he regards as identical with the nuclei of Mr. Robert Brown, or the cytoblasts of Schleiden. A paper was also in part read, entitled, " Sixth Letter on Voltaic Combinations," addressed to Michael Faraday, Esq., D.C.L., F.R.S., &c. By John F. Daniell, Esq., For. Sec. R.S., Professor of Che- mistry in King's College, London, &c. May 5. — The reading of a paper, entitled, ""Sixth Letter on Voltaic Combinations," addressed to Michael Faraday, Esq., D.C.L., F.R.S., Fullerian Professor of Chemistry in the Royal Institution of Great Britain, &c, by John Frederic Daniell, Esq., Foreign Sec. R.S., Professor of Chemistry in King's College, London, was resumed and concluded. The purport of this letter is to follow the consequences of the law of Ohm, and the expressions which result from it, relative to the electromotive force, and to the resistances in the course of a voltaic circuit ; to apply this theory to the verification of the conclusions which the author had formerly deduced from his experiments ; and to suggest additional experiments tending to remove some obscu- rities and ambiguities which existed in his former communications. In following out these principles,- the author is led to offer various practical remarks on the different forms of voltaic batteries which have been proposed with a view either to the advancement of our theo- retical knowledge of the science, or to the service of the arts. The author enters more particularly into an explanation of the principles on which the cylindric arrangement of the battery he has intro- duced is founded, which appear to him to have been greatly misun- derstood. The formulae and the calculations which form the body of this paper are not of a nature to admit of being reported in the present abstract*. May 12. — " On the Rectification and Quadrature of the Spheri- cal Ellipse." By James Booth, Esq., M.A., Principal of Bristol Col- lege. Communicated by John T. Graves, of the Inner Temple, Esq., M.A., F.R.S. The author, at the commencement of this paper, adverts to a rather complex discussion of a portion of the subject of his inquiry by M. Catalan, published in the Journal de Mathematiques, edited by M. Liouville. He then proceeds to establish two fundamental theorems, appli- [* Abstracts of Prof. Daniell's preceding five letters on Voltaic Combi- nations have already been given in Phil. Mag., Third Series; see vol. xv. p. 312. Dr. Martin Barry's paper on Fibre, also read May 5, will be no- ticed in a future Number, together with Lieut.-Col. Yorke's on the Effect of the Wind on Barometers, read May 12th.— Edit.] Royal Society. 5$ cable to, — 1st, the quadrature, and 2nd, the rectification of the sphe- rical ellipse. 1st. The quadrature of the spherical ellipse is reduced to the calculation of a complete elliptic function of the third order, whose parameter and modulus are quantities essentially related to the cone; its parameter being the square of the eccentricity of the ellipse, whose plane is at right angles to the axis of the cone, and its modulus being the sine of the semi-angle between the focals. 2nd. The rectification of the spherical ellipse is made to depend on a complete elliptic function of the third order, whose parameter is the same as in the preceding case, but whose modulus is the sine of the angle between the planes of the elliptic base and of one of the circular sections. The author then proceeds to establish a remarkable relation be- tween the area of a given spherical ellipse and the length of the spherical ellipse generated by the intersection of the supplemental cone with the same sphere. He shows that if there are two concentric supplemental cones cut by the surface of a concentric sphere, — 1st, the sum of their spherical bases, together with twice their lateral surfaces, is equal to the sur- face of the sphere ; 2nd, the difference of their spherical bases is equal to twice the difference of their lateral surfaces. Hence, also, he deduces a remarkable theorem, viz. the sum of the spherical bases of any cone whose principal angles are supple- mental, cut by a sphere, together with twice the lateral surface of the cone comprised within the sphere, is equal to the surface of the sphere. The author then, alluding to some researches of Professor MacCullagh and of the Rev. Charles Graves, Fellow of Trinity Col- lege, Dublin, proceeds to give a simple elementary proof of a well- known formula of rectification, and thence deduces some remark- able properties of the tangent at that point of the ellipse, which is termed by him the point of rational section. Assuming the properties of the plane ellipse, he proceeds to show that a similar formula of rectification holds for any curve generated by the intersection of a spherical surface with a concentric cone of any order. He goes on to develope a series of properties of the spherical ellipse, bearing a striking analogy, as indeed might have been expected, to those of the plane curve. Thus he establishes a point of rational section as in the plane ellipse, shows that the tan- gent arc is at this point a minimum, and developes some other cu- rious analogies. It is a simple consequence of his formula that the spherical elliptic quadrant may be divided into two arcs whose dif- ference shall be represented by an arc of a great circle. This theorem, previously obtained by M. Catalan, is analogous to that of Fagnani, which shows that the difference of two plane elliptic arcs may be represented by a straight line. The author concludes by reducing the quadrature of the surface of a cone of the second degree, bounded by a plane perpendicular to the axis, to the determination of a complete elliptic function of the second order. 56 Royal Astronomical Society. ROYAL ASTRONOMICAL SOCIETY. (Continued from vol. xix. p. 584.) Nov. 12, 1841. — The following communications were read : — I. On the Longitude of Dr. Lee's Observatory at Hartwell. The longitude of this observatory was assumed from various au- thorities to be 3m 20s* 6 west from the Royal Observatory at Green- wich, by the late Mr. Epps, for some time after his arrival at Hart- well. These authorities appear to have been as follows : m s Capt. Smyth, by means of two trips with a chronometer "I „ -1 - from Bedford Observatory J By the moon's culminations as computed by Mr. Riddle 19-9 Mr. Epps, by chronometers 21*7 Ditto 20-7 Mean longitude 3 20-6 The mean of these determinations was naturally supposed by Mr. Epps to be very near the truth. In October 1838 this mean result was found, however, to differ considerably from the difference of meridians as determined by twelve chronometers, taken by Mr. Dent from the Royal Observatory (which was 3m 24s,46). It was evi- dent, therefore, that there was either an error of nearly four seconds of time in the longitude of Hartwell, as previously assumed, or in the observations made there on this occasion to determine the error of the clock with which the chronometers were compared. A care- ful recomputation of the observations, as recorded in the Hartwell transit books, was therefore made, and the result (as far as the re- ductions were concerned) was found to be correct. A reference was then had to Aylesbury church spire, the position of which had been determined by the Trigonometrical Survey. This was done by means of an estimated distance of the spire from the Hartwell Observatory, taken from a county survey, and the observed azimuth of the former from the observatory. This gave a result (3m 23s-07) differing 2S*5 of time from Mr. Epps's former determi- nation, and ls,5 from that obtained from Messrs. Arnold and Dent's chronometers, and was therefore far from being satisfactory. In the following January another series of results was obtained by means of ten chronometers, which were taken by Mr. Dent as before, from the Royal Observatory to Hartwell, on the 6th of that month, and the comparisons made with the transit clock at the latter place on the same day. The chronometers were brought back to the Royal Observatory on the 9th following. The difference of meri- dians by these observations was 3m 24s-06. Other results were also obtained by means of chronometers taken from the Royal Hospital Schools at Greenwich to Hartwell Obser- vatory ; and, in reference to these results, as well as to those before obtained, Mr. Epps observes, in a letter to Mr. Fisher, "The results agreeing so well with the former, I think we may conclude that 3m 24s,2 (as you have already noticed) is extremely near the truth. This may be called the mean result of thirty chronometrical deter- minations. I may remark to you, that my observations for time are made with as much attention as possible to the state of the transit Royal Astronomical Society. 57 instrument ; viz. that it works with no apparent error in collimation, nor level error, but correcting as occasion may require for azimuthal deviation. With the exception, therefore, of minute differences in the right ascensions of the stars by which the clock-errors were deter- mined, and some trifling optical defects, I conclude that nothing of importance can be urged against the mean of all the results. In- deed, all the observations respecting the chronometrical comparisons are plain and straightforward matters of fact in conjunction with the transit observations, as recorded in the observation books." The error in the former assumed longitude being now fully con- firmed by so many chronometrical results, it was resolved to connect in a more accurate manner than before the position of Aylesbury spire with that of the observatory at Hartwell by actual measurement and triangulation ; since it was possible that an error might have oc- curred so as to have caused the discrepancy observed between the chronometrical longitude and that obtained by the Trigonometrical Survey. This was done in April 1840, and the result was nearly iden- tical with that previously deduced by means of the county survey. As there is a considerable error in the longitude of this spire as given in the third edition of the Requisite Tables, Mr. Yolland, of the Ordnance Map Office, very kindly undertook the recomputation of its geographical position from the original data of the Trigonometrical Survey, and found it to be as follows : — 0 t „ Latitude '. . 5149 10 North. Longitude 0 48 50-15 West. In time 3m 15s<34 From this corrected position of the spire, we have the following for the position of the observatory at Hartwell : — Latitude 51° 48' 14"-8 North. Longitude 3m 22s-57 West. Final results for difference of meridians : — m s By the chronometrical determinations 3 24*26 By Aylesbury spire, as determined by the Trigonome- 1 ., 99.k7 trical Survey J J Difference 1*69 II. Observations of the Beginning and Termination of the Solar Eclipse of July 18, 1841, at Aberdeen. By Charles Crombie, Esq. Communicated by George Innes, Esq. The eclipse was observed in the garden attached to Mr. Crombie's residence, which is a short distance from the Marischal College. The instrument used was a 2£ feet achromatic telescope, with a power of about thirty-six ; and the times were taken with a pocket chronometer, whose rate was determined by two comparisons with a clock belonging to Mr. Innes, and the error by several altitudes of the sun. The Aberdeen mean solar times of the beginning and ending of the eclipse, resulting from the observations, are — h m s For the beginning 2 17 48*7 And for the ending 2 58 10'2 58 Royal Astronomical Society. III. Observation of the Lunar Occultation of Venus on September 11, 1841, at Mr. Bishop's Observatory, in the Regent's Park. The occultation of Venus by the moon was observed here, but not under favourable circumstances. The morning was clear, but the wind easterly. The equatoreal telescope was charged with a power of 105. Venus was badly defined in general, the air being in a very disturbed state. The enlightened edge of the moon com- pletely hid the planet at about 18h 31m 21s, Greenwich mean astro- nomical time. The time was not accurately noted, the observer's attention being principally directed to the phenomena of the occul- tation. No projection on the moon's limb, nor any distortion of the form of Venus, was perceivable. The edge of the moon was well seen, and sharply defined on the planet's disc. The commencement of the reappearance at the unenlightened edge was not well caught, the planet becoming visible at some distance from the centre of the field. This being instantly rectified, the dark edge was well seen on the planet, which did not appear in the least distorted. The reappearance was complete at about 19h 41m 54s, Greenwich mean time, and was observed with the power 105. The air had become very smoky, and vision was extremely bad. IV. Notice of the Occultation of Venus on the morning of the 12th of September, 1841. Observed at Malta by Capt. Basil Hall, R.N. Communicated by Capt. Beaufort, R.N. " The beginning of this interesting occultation was observed at Valetta within a second of time, I think I may venture to say. An unlucky cloud prevented my observing the planet's reappearance. Telescope magnifying sixty times. " The following are the times by chronometer : — First contact of the north limb of Venus with the south limb of the moon (civil reckoning) Instant when the centre of Venus appeared cut by "] the enlightened limb of the moon, as nearly as I >6 46 26 could judge J Contact of the eastern, or enlightened, limb of Venus 1 „ >fi "\(\-c\ with the eastern, or enlightened, limb of the moon J Chronometer slow of Malta mean time 1 6 33*2 Mean time at Malta of the disappearance of the "1 eastern limb of Venus behind the east limb of >7 53 9*2 the moon J Difference of longitude 58 xl*8 Mean time at Greenwich of the disappearance of 1 fi -- ,.. the eastern limb of Venus behind the moon. ... J " The time was ascertained by equal altitudes of the sun, and, I think, may be considered correct to about a second. The differ- ence of longitude is taken from the Table No. 8. in Lieut. Raper's recently published work, in which you will observe that the obser- vatory (which is no longer an observatory) on the palace is placed in 14° 30' 42" = 58m 2s-8. But my house lies west of the palace 1 0 Consequently the difference of longitude is 58 1 '8 | 6 45 54 Royal Astronomical Society. 59 " The latitude of my house is the same as that of the observatory, viz. 35° 53' 54", as given by Lieut. Raper ; but I have not yet had an opportunity of verifying this point. " On the voyage to Malta from England, and since my arrival here, I have had ample means of examining the work above alluded to ; and I feel it right to say, — and I hope you will communicate my testimony (such as it is worth) to the Astronomical Society, in favour of the book of my highly valued friend, their secretary, — I have gone over almost every part of the Practice of Navigation, and some of the parts a great many times, and I can say without quali- fication, that I am acquainted with no work so well adapted for the use of sailors, none so luminous and precise in its style, nor so sim- ple in its use. The tables, too, are well arranged and of very ready application, in consequence not only of the distinctness of the pre- cepts, but the good selection of illustrative examples. It is much to be desired that Lieut. Raper should publish his second volume, for such works contribute greatly to the improvement of practical navigation, not merely by the information they furnish, but by rais- ing the standard of accuracy, and teaching that even by moderate, but well-directed, exertions, any ship may be navigated with far more certainty and speed than by the ordinary and loose methods still, unfortunately, too much in use afloat." V. Observations of Bremicker's Comet made with the Equatoreal Instrument of the Observatory of Padua. By M. Santini. As soon as the notice of this discovery was received, the comet was immediately sought for at the Observatory of Padua ; but clouds and the light of the moon prevented it from being seen till the even- ing of the 22nd of November : it was extremely faint, and presented itself under the appearance of a light mass of vapour faintly illumi- nated, without sensible trace of a nucleus. It was observed till the evening of the 27th of November ; after which time other occupa- tions hindered M. Santini from making further observations of it till the 1st of December. After this time the clouds and the light of the moon caused him to give up the hope of seeing it again. Day, Mean Time Apparent R.A. ApparentDeclin. Comparison-Stars from 1840. at Padua. of the Comet. of the Comet. Piazzi's Catalogue. h m g h in s O / il Nov. 23. 9 3 6-5 21 40 12-78 +55 54 37-1 Piazzi xxi. 385. 24. 7 26 8-1 7 51 5-4 21 47 24-58 21 47 31-92 55 25 1-8 55 24 31-8 j-Dittoxxi.373&385. 25. 7 1 33-4 21 54 57-55 54 51 451 1 7 32 49 21 55 4-13 54 50 47-1 \ Ditto xxi. 54 & 92. 8 5 56-2 21 55 6-19 54 49 4-1 J 26. 7 13 137 22 2 35-76 54 15 23-4 1 7 36 40-5 22 2 41*47 54 15 95 \ Ditto. 7 58 32-0 22 2 43-06 54 14 6-5 J 27- 7 33 31-0 22 10 12-29 53 36 56-0 1 7 56 38-6 22 10 1695 - 53 35 40-8 \ Ditto xxii. 92 & 137. 8 8 34-7 22 10 26-32 +53 36 23-8 i M. Santini has computed elements of the parabolic orbit of the 60 Royal Astronomical Society. comet, based on the observation made at Berlin on October 28, com- municated to astronomers by M. Schumacher; on that made at Vienna on November 12 ; and on the mean of the above positions of November 24. The following are the elements derived : — Perihelion passage, November, 15*25525 *, Berlin mean time. o / Long, of the perihelion. . 23 42*5 from the true equinox. Long, of the node 248 47*7 Inclination 58 5*05 ... ... Motion Direct. Log. perihelion dist. = 0*16984 perihelion dist. = 1*4786 VI. Introduction to a Catalogue of 1677 Stars included between the Equator and 10° of North Declination, observed at the Royal Observatory of Padua. By M. Santini. Communicated by Sir J. F. W. Herschel, Bart. The observations of the stars in this catalogue were made with a meridian circle constructed by Starke, a description of which is to be found in the fifth volume of the Transactions of the Academy of Padua. The object of M. Santini has been so to arrange his new catalogue that, at every eight or ten minutes of right ascension, there should be found in each parallel of declination a well-deter- mined star, with the view of facilitating the comparisons of planets and comets with neighbouring stars, by means of micrometrical measurements. The brightest stars that could be found were chosen for this pur- pose, very few being admitted which are below the eighth magnitude. They were observed for convenience of reduction in contiguous groups, in such a manner that the corrections necessary for reducing them to the mean equinox of 1840 might be applied to the mean of the apparent positions observed, for the mean instant of the series ; and the greater number of the stars were observed three times in both elements. It is the author's intention to proceed immediately with similar observations of stars in the zone extending from the equator to 20° of south declination ; and he invites astronomers to participate in his labours by observing some other zones. The observed right ascensions of Bessel's fundamental stars were compared with their right ascensions given in the Berlin Ephemeris, for obtaining the clock-correction ; and the azimuthal deviation of the instrument was obtained by the superior and inferior transits of Polaris. The polar point of the circle was obtained by observed zenith distances of Polaris and the same fundamental stars, using Carlini's Refraction Tables, and the apparent declinations of the Berlin Ephe- meris. The agreement of the individual results both for clock errors and for polar point was in general highly satisfactory. To obtain the mean places for 1 840, small special tables were used similar to those * In the manuscript the time of the perihelion passage is also written 3201-24525. London Electrical Society. 61 employed for Bessel's zones, the values of the constants, /, g, h, i, G, H, of the Berlin Ephemeris being adopted ; and in the annual variations no allowance has been made for proper motions of any of the stars. LONDON ELECTRICAL SOCIETY. Feb. 15, 1842. The papers read were, — 1st, "On the Electrical relation between Plants and Vapours." By Mr. Pine. The author, still pursuing the same path as that traced out in his former communica- tions, makes copious extracts, from various quarters, both of natural and experimental facts, in support of his views of the relation be- tween the subtle fluid— electricity, and the functions of vegetable life. His opmions and reasonings are worthy of examination. 2nd, " Further Observations on Electrotype Manipulation — Depo- siting on Plumbago — Electro-lace." By Charles V. Walker, Esq., Hon. Sec. The difficulty attendant on the reduction of copper upon the parts of plumbagoed surfaces most remote from the connect- ing wire, is obviated by a very simple process. One or more fine leading wires are twisted round the main wire, and made to abut upon any part of the surface where the reduction has not occurred. The value of this apparently trivial piece of information can be ap- preciated by experimentalists alone. The material, to which the term " electro-lace" has been given (and of which specimens were before the Society), is obtained by depositing copper upon net or lace, previously prepared with wax and black-lead. It was first fa- bricated by Mr. Phillips of Cornwall, in lieu of the copper gauze re- quired in the construction of Prof. Grove's modification of Smee's battery. But it will be readily seen that such fabrics as gauze and lace, when covered with copper, and plated or gilded, may be intro- duced, in a multitude of ways, into the construction of ornamental work, where at present embossed and perforated cards are employed. 3rd. " Nitrate of Soda compared with other Salts employed for Constant Batteries." By Geo. Mackrell, Esq., Mem. Elec. Soc. Cells were excited with solutions of sulphate of copper, bichromate of potash, nitrate of potash, and nitrate of soda. The palm of supe- riority, for constancy of action, is awarded to the latter : in addition to this, when employed for electrotype purposes, it throws down more copper in proportion to the zinc consumed, than either of the other three : the zinc plates (no slight advantage) are clean when removed from the battery. Mr. Weekes's Register for January was next read. At the sug- gestion of several scientific correspondents, with a view to promote the objects of coincident observation, Mr. Weekes begins the Register of 1842 by giving the readings of the barometer and thermometer at 9 a.m. instead of 2 p.m. March 15. — The papers read were, — 1st, "Details of an experi- ment, in which certain insects, known as the Acarus Crossii, appeared, incident to the long-continued operation of a voltaic current upon Silicate of Potash within a close atmosphere over mercury." By W. H. Weekes, Esq. 62 London Electrical Society. After alluding to the original experiment of Mr. Crosse, and to the objections made that the insects might have sprung from ova in the atmosphere, Mr. Weekes states that he had resolved to pro- vide against such contingencies. This he effected by placing the solution, which was prepared with the utmost caution, beneath a bell-glass, which has not been disturbed from Dec. 3rd, 1 840. Late in October 1841 the first insect was detected; on Nov. 27th several were seen : since then they are constantly to be seen, sometimes solitary, at other times in pairs, and occasionally three or four to- gether. The operation was conducted in the dark, light being only admitted at those times when the progress was under examination. The voltaic current was from a short series of Daniell's battery. These creatures appear to love darkness ; for on the admission of a ray of light they hasten away and seek hiding-places in the recesses of the apparatus. Simultaneously with this another arrangement was made, in which the current from a water battery was made to pass through a solution contained in a bell-glass of oxygen. Insects appeared in this on the 20th Feb. 1842, and eight or ten fine vigo- rous Acari were visible. This is but a brief summary from a very long and carefully written communication. The author assumes nothing ; he does not venture to theorise, but gives a plain and ex- plicit account of his experiments and of their results. The operation is still going on, as there is every reason to expect a further deve- lopment of insect life. More completely to preclude objections, he is preparing another apparatus in which nothing but glass, metal, and mercury (distilled from its sulphuret) will enter. 2nd. " Note on Electro -tint, and on etching Daguerreotype Plates." By W. G. Lettsom, Esq., M.E.S. This note was illustrated by specimens of tints produced by Prof. Von Kobell of Munich, and Dr. Berres of Vienna. The former has improved upon his original process of electro-tint by a method of retouching the plates and then reobtaining others. 3rd. Extracts of a letter from John Samo, Esq., of Surinam, M.E.S. , containing " Information respecting the Gymnotus Electri- cus." Among the specimens possessed by Mr. Samo were two in one tub, whose relative lengths Were SO and 15| in. The smaller was missed, and it was found that the other had swallowed it. He soon however cast it up, and in the space of a few hours died. On post- mortem examination it was found that the stomach was considerably ruptured. Mr. Samo mentions that the report that a certain drug is an antidote to the shock of the Gymnotus is without foundation. 4th. The Secretary then communicated to the Society the death of the London Gymnotus, which has from time to time furnished such interesting results to Prof. Faraday, Dr. Schcenbein, Mr. Gassiot, and others. 5th. " On Voltaic Apparatus." By James P. Joule, Esq., M.E.S. The author details the results of a series of experiments upon local action, and upon the relative intensities of several voltaic arrange- ments under different circumstances. London Electrical Society. 69 6th. Mr. Weekes's Electro-Meteorological Register for February 1 842 was then submitted to the Society *. May 17. — A note from Mr. Weekes was read, stating that, when he commenced those experiments, during which insects had been developed, he made similar arrangements, and placed tbem in va- rious parts of his house, without allowing the voltaic current to pass through them ; and in no case, by the strictest examination, could he detect any appearance of the insect. A paper "On Lightning Conductors, and on the Lightning. Flash which struck BrixtonChurch," by CharlesV.Walker,Esq.,Hon.Sec, was next read. Having examined the steeple of this church, which was struok by lightning on Sunday, April 24th, the author of the paper saw in the damage done so good an illustration of the opinions delivered by Dr. Faraday a few days previously at the Royal Institution, that he was induced to survey more carefully the path, and report it to the Society. We cannot, without drawings, enter into detail on the sub- ject, but will condense the general conclusions which result from the investigation. The steeple was surmounted by a copper cross, which formed the first good conductor : the second was twenty feet from this, and in passing along the interval the masonry about the cross was shivered to pieces, and the cross itself was forced out of its place : the third conducting series was twelve feet from the second : here a second explosion occurred, and the base of a column three feet in diameter was shattered and the column rent. How strange it is that such occurrences as these are not better guarded against ! If the " lateral discharge" is not well understood, the " disruptive" is. The " lateral discharge" occurred in the belfry ; and Mr. Walker showed how it was connected with that property of electricity which induces it to take the widest as well as the shortest road. He ex- plained that, when the fluid is passing along a most ample conductor, some of it will enter vicinal conductors, developing light and heat. The main object of the communication was to trace the connexion between the experiments of the Royal Institution and the pheno- mena illustrated by nature on a large scale. He then explained the method of conveying the fluid safely and tranquilly into these vicinal conductors, by forming metallic communications between them and the lightning rod ; otherwise a lightning rod may become a most dangerous enemy instead of a trustworthy protector. Extracts of Notes from the Rev. Mr. Lockey, Mr. Clarke and Mr. Mayo were read, containing valuable additions to our present know- ledge on Electrotype Manipulation. Mr. Lockey introduces black- lead in his composition moulds, and Mr. Mayo flake-white. The moulds with the latter were exhibited, and were superior to any we have seen. A copper medal, with a silver surface for the design, by Mr. Clarke.was exhibited. Mr. Weekes's Register was then read. June 21st. — " A Notice on Native Malleable Copper," by John A. Phillips, Esq., of St. Austell, was read, in which the author states that copper in this form, as well as arborescent and moss copper, is produced by an action in principle the same as that artificially em- * The proceedings for April will be noticed in a future Number. 64f Royal Irish Academy, ployed in the electrotype process. Several mineralogical specimens were submitted to the Society. A long and highly interesting paper was then read, " On the Transfer of Mineral Substances, through various Fluids, by Electric Agency," by Andrew Crosse, Esq., Mem. Elec. Soc. The first experiment related in this paper was as follows : — Mr. Crosse kneaded some pipeclay into the consistency of putty, and imbedded in it a piece of limestone and a shell ; this was in a basin : he then made a mixture of powdered sand and sul- phate of iron which he placed above the pipeclay, and having filled the vessel with water he allowed the whole to stand for many months. This arrangement was made in imitation of a natural arrangement of like character which had fallen under his notice, and in which the shells and carbonate of lime had become coated with sulphate of lime. In hopes of attaining the same result artificially, this experi- ment was instituted ; and to the great satisfaction of the author when he examined the results, the shell and the limestone had lost in weight, and around each were crystals of sulphate of lime. It is Mr. Crosse's strong conviction, that though many mineral produc- tions may result from the direct action of electric currents, yet far the largest portion proceed from operations analogous to this, — from the direct electrical affinity or attraction between particles of matter coming into contact by this slow and constant action. The only point in which this experiment differed from nature is, that the vessel in which the operation was carried on was not porous. On this point Mr. Crosse stated a fact which will not be forgotten by electrotypists, that voltaic deposits are more abundant when the vessel employed is porous, so that the sulphate of copper can slowly filter through. A series of experiments, some completed, others in progress, were then described, in one of which the mould of a sove- reign was produced in solid marble, by an action not dissimilar in principle to that just described ; and in a modification of the ar- rangement a rod of glass, connected with the positive end of the battery, was gilded. The author does not doubt the possibility of forming any minerals, even the precious gems, by electric agency. He thinks the pearl to be nothing more than alternate layers of animal and mineral substances, electrically concreted. In one of the experiments a magnificent group of fine Acari were developed : the production of these insects is still an object of attention to Mr. Crosse, and he anticipates ere long communicating with the Society on the subject. Mr. Weekes's Register was then read : and the Chairman stated that Mr. Walker's second paper on Lightning Conductors would be read at the next meeting. ROYAL IRISH ACADEMY. [Continued from vol. xx. p. 600.] May 10, 1841. — A Note on some new Properties of Surfaces of the second Order, by John H. Jellett, Esq., F.T.C.D., was read. I. Let the points on the focal conic, at which the tangent is par- allel to the trace of the tangent plane, be considered analogous to foci. Royal Irish Academy. 65 II. Let the axis of the surface, perpendicular to the plane of the conic, be considered analogous to the conjugate axis ; then, since the square of the distance from focus to centre, in a conic, is equal to the difference between the squares of the transverse and conju- gate semi-axis, we may consider, as analogous to the transverse semi-axis, the line drawn to the extremity of the perpendicular axis from the point analogous to the focus. III. Since the square of the semiconjugate diameter is equal to the sum of squares of semiaxes minus the square of central radius vector, let the same be supposed true of the line analogous ; i. e. if A be the line analogous to the transverse, and B to the conjugate semi-axis, let B'= V A2 + B2 — A'2. Assuming these definitions, we shall have the following theorems analogous to those in piano. 1 . The sum or difference (according as the focal conic is perpen- dicular to a real or imaginary axis) of the distances from the points analogous to the foci, to the corresponding point on the surface, is equal to 2 A. 2. The rectangle under them = B'2. 3. The sine of the angle, made by either with the tangent plane, . B 13 W 4. The rectangle under the perpendiculars from these points on tangent plane = B2. 5. The sine of the angle between the central radius vector and A J\ tangent plane = -^rs (A' beinS the central radius vector). 6. The portion of the normal intercepted between the surface and the plane of the focal conic is -jr . B'. 7. If a plane be drawn perpendicular to the line joining points A2 analogous to the foci, and at a distance from the centre equal to -p- (C being the distance of one of the focal points from the centre), the distance of a point in the surface from the corresponding focus will be to its distance from this plane : : C : A. 8. Hence, given a focal conic and the perpendicular axis, we can find points and tangent planes ad libitum, by the following construc- tion:— Take in the focal conic two diametrically opposite points; with one as centre, and twice the distance from it to the extremity of the perpendicular axis as radius, describe a sphere. Through the other point draw a plane, normal to the focal conic ; it will cut the sphere in a certain circle. Connect any point in this circle with the two points on the focal conic, and at the middle point of the line connecting it with the second point draw to it a perpendicular plane. This is a tangent plane to the surface, and the point where it cuts the first connecting line is a point on the surface. Another mode of generating the surface is easily derivable from (7 .). Phil. Mag. S. 3. Vol. 2 1 . No. 1 35. July 1 842. F 66 Royal Irish Academy. TABLES Nos. I. Showing the Chemical and Physical Properties of the Atomic 1. 2. 3. 4. 5. 6. 7. i 2 . Chemical Composition by Atomic Specific Frac- 1 1 | 1 Constitution. weight per cent. weight. gravity. Colour. ture. i — < + » + H = 1 ' 1 Cu + 100-00+ 0 31-6 8-667 Tile red E. 2 10Cu + Zn 90-72+ 9-28 348-3 8-605 Reddish yel. 1 C.C. 3 9Cu + Zn 89-80+ 10-20 316-7 8-607 Reddish yel. 2 F.C. 4 8Cu + Zn 88-60+ 11-40 285-1 8-633 Reddish yel. 3 F.C. 5 7Cu + Zn 87-30+ 12-70 253-4 8-587 Reddish yel. 4 F.C. . 6 6Cu + Zn 85-40+ 14-60 221-9 8-591 Yellowish red, 3 F.F. c 7 5 Cu + Zn 83-02+ 16-98 190-3 8-415 Yellowish red, 2 F.C. N 8 4Cu + Zn 79-65+ 20-35 158-7 8-448 Yellowish red, 1 F.C. T3 a 9 3Cu + Zn 74-58+ 25-42 1271 8-397 Pale yellow F.C. 1 1(1 2Cu + Zn 66-18+ 33-82 95-5 8-299 Full yellow, 1 F.C. 01 11 Cu + Zn 49-47+ 50-53 63-9 8-230 Full yellow, 2 C.C. §■• 12 Cu + 2Zn 32-85+ 67-15 96-2 8-283 Deep yellow C.C. O i;s 8 Cu + 17 Zn 31-52+ 68-48 801-9 7-721 Silver white, 1 C. 1. 14 8Cu + 18 Zn 30-30+ 69-70 834-2 7-836 Silver white, 2 V.C. i-i 15 8Cu + 19 Zn 29-17+ 70-83 866-5 8-019 Silver grey, 3 C. W i-i h; 8Cu + 20 Zn 28-12+ 71-88 898-8 7-603 Ash grey, 3 V. < 17 8 Cu + 21 Zn 27-10+ 72-90 931-1 8-058 Silver grey, 2 C. H 18 8Cu + 22 Zn 26-24+ 73-76 963-4 7-882 Silver grey, 1 C. 111 8Cu + 23 Zn 25-39+ 74-61 995-7 7-443 Ash grey, 4 F.C. 20 Cu + 3Zn 24-50+ 75-50 128-5 7-449 Ash grey, 1 F.C. 21 Cu + 4Zn 19-65+ 80-35 160-8 7-371 Ash grey, 2 F.C. 22 Cu + 5Zn 16-36+ 83-64 1931 6-605 Very dark grey F.C. $a + Zn 0+100-00 32-3 6-895 Bluish grey T.C. r i Cu + Sn 100-00+ 0 31-6 8-667 Tile red E. 2 10Cu + Sn 84-29+ 15-71 374-9 8-561 Reddish yel. 1 F.C. Q 3 9Cu + Sn 82-81+ 17-19 343-3 8-462 Reddish yel. 2 F.C. H 4 8Cu + Sn 81-10+ 18-90 311-7 8-459 Yellowish red, 2 F.C. c g 7Cu + Sn 78-97+ 21-03 280-1 8-728 Yellowish red, I V.C. « (5 6Cu + Sn 76-29+ 23-71 248-5 8-750 Bluish red, 1 V. p. 7 5Cu + Sn 72-80+ 27-20 2169 8-575 Bluish red, 2 C. 8 4Cu + Sn 68-21+ 31-79 185-3 8-400 Ash grey C. u* !) 3Cu + Sn 61-69+ 38-31 153-7 8-539 Dark grey T.C. 1 10 2Cu + Sn 51-75+ 48-25 1221 8-416 Greyish white, 1 V.C. MH 11 Cu + Sn 34-92+ 65-08 90-5 8-056 Whiter still, 2 T.C. M 12 Cu-f- 2Sn 21-15+ 78-85 149-4 7-387 Whiter still, 3 C.C. J ■ 1,'! Cu-j- 3Sn 15-17+ 84-83 208-3 7-447 Whiter still, 4 C.C. £ 14 Cu + 4Sn 11-82+ 88-18 267-2 7-472 Whiter still, 5 C.C. is Cu-}- 5Sn 9-68+ 90-32 3261 7-442 Whiter still, 6 E. [M + Sn 0+100-00 58-9 7-291 White, 7 F. Abbreviations used in Column 7th to denote character of fracture : — F.C. Fine Crystalline, C.C. Coarse Crystalline, T.C. Tabular Crystalline, F.F. Fine Fi- brous, C. Conchoidal, V.C. Vitreo-Conchoidal, V. Vitreous, E. Earthy. The maxima of ductility, malleability, hardness, and fusibility, are = 1 . The numbers in Column 6th denote intensity of shade of the same colour. The atomic weights are those of the hydrogen scale. The specific gravities were determined by the method indicated in Report " On Action of Air and Water on Iron," Trans. Brit. Assoc, vol. vii. p. 283. The ultimate cohesion was determined on prisms of 0-25 of an inch square, without having been hammered or compressed after being cast. The weights Royal Irish Academy. AND II. Alloys of Copper and Zinc, and of Copper and Tin. 67 8. 9. 10. 11. 12. 13. 14. c* . .Sj= £ 'H i 1 1J 5 -1 ■ 3 Relation to VI s Ir a .c o 1 % Characteristic properties, in Working, &c. cast iron, in presence of a solvent, i. e. u V ■a ft* *-* hi * 1-8 0 17 11 2 Brittle. -So '3 15-2 13 12 23 1 Brittle, well known. ■*« ■£ .2 « 24-6 1 2 10 16 Well known. "'gco 161 2 6 8 15 Gun-metal, &c. 1 ^ 15-2 3 7 5 14 Gun-metal, &c. 1 1 - B 177 4 10 4 13 Gun-metal and bronze. .5 S 8* 13-6 5 11 3 12 Hard mill brasses, &c. 1 = 3 3 S and in the analysis of which Abich has so success- fully employed carbonate of barytes, are completely and readily de- composed by fusion with bisulphate of potash. He first employed it in the analysis of the chlorospinelle of Fla- tonsk : this mineral was reduced to fine powder in a steel mortar without having been previously bruised in an agate, flint or chalce- dony mortar, was heated with bisulphate in a platina crucible over a spirit-lamp with a double current of air, until the powder was com- pletely dissolved. The fused mass dissolved entirely in water, and the constituent principles of the solution may be determined by the well-known methods. The alumina, when the quantity is not too small, ought to be redissolved in hydrochloric acid, and precipitated by carbonate of ammonia, to avoid an excess of it in the result. The use of the bisulphate of potash especially requires this precaution, because the salts of the fixed alkalies are separable with so great difficulty from precipitated alumina by washing. M. Rose did not find any silica in the chlorospinelle, although Meteorological Observations. 79 this mineral occurs in schistose talc, and consequently in a silicate. A series of experiments proved that silica is entirely wanting in na- tive aluminates, such as the corundum of China and Bengal, Oriental sapphire, the spinel of Ceylon and Norway, the gahnite of Ekeberg ; and that the silica found by other chemists comes from the agate mortar in which the mineral is pulverized. Though the bisulphate of potash is very advantageously employed in the analysis of aluminates, it is not applicable to that of those si- licates which are not decomposable by acids. Felspar is only par- tially decomposable by this salt : it is therefore evident that silica is a much stronger acid than alumina when it acts the part of an acid ; for if the bisulphate of potash so readily effects the decomposition of aluminates, it is entirely because alumina always acts as a base with sulphuric acid. — Ann. der Chem.und Pharm., and Journ. dePharm. et de Chim., Mai 1842. SOCIETE GEOLOGIQUE DE FRANCE. We are able to inform our readers, that the great Annual Meeting of the French Geologists will take place this year on Sept. 4th, at Aix (dept. Bouches du Rh6ne), and we have no doubt will be at- tended by a vast number of foreigners, attracted both by the beauty and geological interest of the neighbourhood. METEOROLOGICAL OBSERVATIONS FOR MAY 1842. Chiswick. — May 1,2. Clear and very dry. 3,4. Very fine. 5. Cloudy: heavy rain. 6. Fine: showery. 7. Rain: stormy showers. 8. Cloudy: stormy. 10, 11. Very fine. 12. Drizzly. 13 — 15. Slight haze in the mornings: very fine : clear at night. 16, 17. Very fine: clear. 18, 19. Overcast. 20. Densely clouded. 21. Cloudy and fine. 22. Cloudy and fine: slight rain. 23. Cloudy. 24. Rain. 25. Rain : overcast. 26. Rain : cloudy : clear at night. 27. Cloudy and fine. 28. Very fine. 29,30. Clear and very fine. 31. Very fine : cloudy. Boston. — May 1, 2. Fine. 3. Cloudy. 4. Fine. 5,6. Fine : rain p.m. 7. Cloudy: rain a.m. and p.m. 8. Windy. 9 — 11. Fine. 12. Rain. 13. Fine. 14. Foggy. 15, 16. Fine. 17— -19. Cloudy. 20. Rain. 21, 22. Cloudy. 23. Fine. 24. Rain : rainy day. 25. Cloudy. 26. Rain : rain early a.m. 27. Cloudy. 28. Fine: rain early a.m. 29. Fine. 30. Cloudy. 31. Fine. Sandwick Manse, Orkney. — May 1 . Clear : fog. 2. Cloudy : clear. 3. Clear : cloudy. 4. Cloudy : damp. 5. Cloudy: rain. 6. Bright: cloudy. 7. Cloudy : thunder. 8. Showery. 9. Cloudy. 10. Rain: clear. 11, 12. Cloudy. IS- IS. Clear. 16. Clear: fog. 17. Fog cloudy. 18. Cloudy. 19. Cloudy: drizzle. 20. Cloudy: shower. 21. Bright: shower. 22. Clear. 23. Clear: fog. 24. Clear: cloudy. 25. Cloudy: damp. 26. Bright: cloudy. 27. Bright : shower. 28. Bright : cloudy. 29. Cloudy : showery. 30. Bright : cloudy. 31. Bright. ■dpplegarth Manse, Dumfries-shire. — May 1,2. Dry and withering. 3. Cloudy. 4. Fine. 5. Cloudy, with rain. 6. Showery. 7. Wet day. 8. Showers a.m. : cleared. 9. Fair, but cool. 10. Fair, but threatening. 11. Showery. 12 — 17. Fair and fine. 18. Fair and fine, but cloudy. 19. Fine rain p.m. 20. Rain and hail. 21. Fair and fine. 22. Showery. 23. Showery: growing weather. 24. Showery. 25. Fair and fine. 26. One shower : fine p.m. 27. Fair and fine. 28. Fair till noon : then rain. 29,30. Showers. 31. Slight showers. Sun shone out 29 days. Rain fell 12 days. Thunder 2 days. Hail 1 day. Wind North-east 1 day. East 3 days. East- south-east 1 day. South-east 5 days. South-south-east 4§ days. South 5 days. South-west 4$ days. West- south-west 4 days. West 1£ day. North-west 1£ day. Calm 7 days. Moderate 14 days. Brisk 2 days. Strong breeze 6 days. Boisterous 2 days. 13 . 1 n * 2 u J3 a Ps5Q SI | §>*^ B « 1 § *» s ^■86 ■« 5 > if -5 !£^ -2 ^ "a ■*s «j a S "•* •« -* - 2 •*| I b Q u ■3*5 « I! 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T © id p w n n « p coo NNoo co co co ao ^ o - _.0©©©©©©OiOlOiCiO>OiOiOiOi©©0© «C0CNCNCNCTCNC*C0mCNNCOC0WMCOC0CNWoo«f^'t^O'tcooocO'-NmoP)Oiiocoooccinco-.oi o o aooi^ n^ci«ooipw^^copco nnnoo co aa ao h o « © ©OiOlOiOlCTlO^O)©© C7l© © © ©©©OiO^CTlOlOlC.OlOlbl©©©© COWCNWCNCNeNCNCNCOCOCNMeOWCOMCOeNCNCTCTCN H«W1"0'-ON00C3>O'H0in^,i01ONC0O5Oi- 2 tO NX OJ©"-< 'CNWeNCNCNCNCNCTCNC^COCO o THE LONDON, EDINBURGH and DUBLIN PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. [THIRD SERIES.] AUGUST 1842. XV. On the Scientific Labours o/*Jeremias Benjamin Richter. Addressed to the Imperial Academy of Sciences of St. Peters- burg, at the public sitting of Dec. 29, 1840, by M. Hess, Member of the Academy*. Gentlemen, THERE is perhaps no one here present who does not reckon amongst the fairest enjoyments of thought those moments which from time to time he is able to devote to the remembrance of men of genius who have bequeathed to us important truths. And when I proceed to show that the veil which obscures the memory of one of these has yet to be torn away, — that the labours of twenty years employed in ren- dering a truth evident to the eyes of the most incredulous, are not yet appreciated, — you will then, I cannot doubt, grant me a moment of the attention which your kindness would not have refused to a cause less disinterested. In the exact sciences, as in all other cases, nature does not allow us to proceed per saltum ; it is necessary that every thing should be unfolded gradually. It is the most simple phaeno- menon which first takes its place in the domain of intelligence ; the most complicated — themostdifficull, is that which comesthe last. Thus when at the beginning of the eighteenth century, astronomy, thanks to the numerous labours summed up by the mind of one great man, thanks to the simplicity of his prin- ciple, assume'd the rank of a science almost perfect, about that time did chemistry, with difficulty, attempt to assume a sci- entific form. You will perhaps suppose that this is to be at- tributed to the men who were engaged in it; but you will soon abandon this idea when I tell you that Newton, who dis- covered the law of gravitation, also applied himself to che- mistry, that he decomposed the subtile matter of light, whilst * From the Recueil des Actes de la Seance Publique, Dec. 29, 1 840. Phil. Mag, S. 3. Vol. 21. No. 136. Aug. 1 842. G 82 M. Hess on the Scientific Labours of Richter. not only the air, but water and even earth still resisted the efforts of three generations. However, George Stahl, a resident at Berlin, established his theory of phlogiston which so long preserved its dominion in the mind. Air was at last decomposed, and water also. Lavoisier next analysed the phaenomenon of combustion ; and from this period the new ideas became diffused; the im- pulse was given, earth itself was analysed, and the number of combinations was increased in a wonderful manner, without the existence as yet of any known law to reduce this labyrinth to order. Many persons still remember the manner in which analyses were recorded ; everythingwas reduced to hundredths, and thence resulted a confusion the shackles of which must have been felt, in order to appreciate the system of notation now used, at its just worth. It was Jeremias Benjamin Richter, assessor at the office of mines at Berlin, who first gave order to this chaos. You therefore would expect that the highest esteem would invest his works, that his name was revered. No; Richter was not appreciated, he was almost forgotten whilst alive. He died at Berlin the 4th of May, 1807. The same year a celebrated author tells us, that being employed in drawing up a treatise on chemistry, amongst other works but little read he ran through those of Richter. He was struck with the mass of light which he found there ; but by a fatal chance he attributed to Wenzel, whose works he must have read at the same time, the most beautiful result obtained by Richter, that which was to serve for a foundation to the whole edifice. In order to explain how it was that Richter had been forgotten, the author to whom we allude says that his results were not exact, which must have weak- ened the impression the perusal of his works must have made, and so much the more as Richter almost always took the carbo- nate of alumina as the point of departure, a combination which we know does not exist. Let us not be surprised, then, that the most celebrated French authors repeat, on the authority of a great name, the same errors concerning works which they have not read ; we see, for example, the author of the Leqons sur la Philosophic Chimique explain things in the same way, and reduce the merit of Richter almost to nothing. " Can you believe," says he, '* that in establishing his doctrines he nearly always takes the carbonate of alumina as the point of depart- ure ?" In short, Richter is there reproached with having too much obscured the questions upon which Wenzel had begun to throw light *. [* Our own countryman Dr. Wollaston, it would appear, justly appre- ciated the labours of Richter : see the paper explaining his "Synoptic Scale of Chemical Equivalents" in the Philosophical Transactions for 1814, p. 3, 4. —Edit.] M. Hess on the Scientific Labours of Richter. 83 If in general, gentlemen, it is a duty to render justice to merit, in the present case it is at the same time a right; for J. B. Richter, almost unknown by the rest of Europe, was elected a correspondent of this Academy on the 1 4th of May 1800. Let us examine his title to our esteem. It is the best homage we can render to his memory. Richter published in 1792 and 1793, a work in three vo- lumes under the title of Anfangsgrunde der Stochiometrie, oder Messkunst chemischer Elemente, in which he sets forth his ideas in the form of a systematic treatise. But this form, you know, is little suited for spreading new ideas. How can a reader be expected to gather five hundred known ideas in order to discover one that is original ! Has not each professor his treatise, and would it not be a punishment to have to study nearly the greater part of it? This mode of publication does not promise success to any but authors who have already ac- quired great celebrity, and with whose works we are obliged to become acquainted. So Richter, beginning by a work in three volumes, was not read. Seeing that the great truth which he had in view was not appi'eciated, that he was exposed to unjust cri- ticisms, whilst his work was not read, he resolved to publish his researches separately, which he did under this title, Ueber die neueren Gegenstdnde der Chemie, in eleven small volumes of from 100 to 250 pages each. They appeared from 1793 until 1802. "I should (says Richter in 1799) certainly not have followed up these two first volumes (Stiicke) by seven others, if too severe a criticism of the antiphlogistic school did not endeavour to put under the bann of sound reason all those who think differently from it, and if to this was not added the annoying circumstance that my Stochiometrie, although endowed with a sound constitution, is nevertheless consigned to the shelf of the shop-keeper." In the introduction to the first part, Richter tells us he hopes that the part of chemistry which treats of affinities and quantities will soon become a part of applied mathematics. Here then is the preconceived idea, the point whence Richter set out; — weigh even the form of his expressions, and you divine nearly all his life. " Some experiments which I have just made, having the same aim in view (says Richter, vol. i. § 121), make me think that if we could employ suitable expedients, we should find that the neutrality of pure ele- ments, setting out from one amongst them which is taken as unit, increases in a positive progression." We see the idea was truly philosophical ; it was necessary to develop it and to become assured whether such a relation existed or not. It was a source of serious errors to him, and drew upon him too severe judgements. He devoted a part of his works to fathom G2 84- M. Hess on the Scientific Labours of Richter. this question, and remained persuaded that the equivalent of all bases belongs to an arithmetical progression, whilst the numbers, which express the equivalents of the acids, form geometrical progressions, the ratio of which is different ac- cording to the different groups of acids. Now it is well established that facts do not support this no- tion of Richter's: we shall therefore pass over this part of his works, and I shall return to them but once, in order to show how it was that his experiments were sometimes so far from the truth as not to undeceive him. But if we go back to the time when he lived, we shall feel that the question raised was vast, and that if his undertaking was not crowned with success, he at least deserves that these words should be applied to him: " Quern si non tenuit, magnis tamen excidit ausis." Amongst the numerous subjects which Richter treats of in the first volume, I shall only quote the method which he points outforextractingplatinum from the ore of that metal ; foritis still used. He recommends precipitating the solution of that metal by sulphate of potash, to wash and dry the precipitate and to decompose it by the carbonate of potash, so as to divest it afterwards of all the salts by washing it with water. The metal then remains brilliant as silver. The explanation of the processes follows, which gives him an opportunity of making some very important remarks. When we shall have found, says he, numerical expressions for affinity, then these seeming anomalies will disappear. Upon this occasion he explains the difference between simple affinity and double af- finity, and observes that it is nowhere proved that we can really isolate a simple body, for, he says, each time that we disengage an alkali or a metallic acid, if it be only carbonic acid, heat must then be substituted for the acid ; lime is an example of this. So it is with the acid from which we take a base, it is combined with, or even neutralized by heat. In the case of a simple affinity, we suppose but two elements, whilst this shows you that there are at least three, for every time that neutrality takes place, heat is substituted for the third element. This is even the case when a metal is dissolved by an acid and neutralizes it, for then it is the acid that furnishes the heat, which becomes united with the other elements. Richter therefore knew that bodies were pervaded by heat; he urges the necessity of taking these phaenomena into con- sideration, but he does not yet take a perfectly just view of them; he believes that heat is just added to the elements, when we know, on the contrary, that it has just been disen- gaged. M. Hess on the Scientific Labours o^ Richter. 85 The third volume (1793) is wholly devoted to a critical ex- amination of Lavoisier's antiphlogistic system. Up to that time Richter had only known it by very insufficient extracts. But in 1792 appeared a German translation of Lavoisier's treatise on chemistry, by Girtanner. Richter obtained and read it, and was convinced of the truths of the new system. Yet indulgent towards others and a stranger to the spirit of party, he excuses those who refuse to admit it. " For," he says, " in the ancient system, metals and sulphurs were con- sidered as compound bodies, earths and acids as simple bodies; in the new system it is just the contrary : now imagine a man whom you would persuade that all he sees he sees reversed, and then condemn him for his incredulity. But, neverthe- less, an error does not become a truth should it even count myriads of ancestors." Do not suppose however that Richter, upon embracing the new system openly, abandons himself to it without criticism. No. No one to my knowledge has better perceived what there was good in the fundamental principle of the phlogistic system. We must not expect that a system which served, for nearly a century, as a starting-point for the numerous investigations of chemists, that a system which could rally round it all facts, should be entirely illusive. " All the facts on which the partisans of the antiphlogistic system rest," says Richter, " are not only insufficient for the refutation of the reality of phlogiston; but on the contrary, they do but rectify our ideas with regard to it and render its existence more evi- dent ; for example, when we assert that phosphoric acid is composed of phosphorus and oxygen, this conclusion has no foundation, since in reality no other conclusion can be drawn from the experiment, except that this acid is composed of the radical of phosphorus and of oxygen. Not any induction can be drawn respecting the nature of this radical itself, for it is only known as combined with oxygen or with phlogiston (Brenn- stoff). ; which, however, does not prevent us from indicating the relative quantity of the elements, since, for us, the weight of phlogiston, like that of heat, is an infinitely small quantity." Such was the capacity of Richter's mind, that in the midst of the lively contention of two parties who do not agree, he quietly examines the question, seizes the literally palpable truths of the new school, and yet does not abandon the more abstract, more hidden but not less real truths of the old system. Per- haps Richter had a model, but then this model was Lavoisier, and no other. But it is certain that at the present time, this manner of viewing the subject is banished from all works which treat of this science, and that it is after a lapse of forty years 86 M. Hess on the Scientific Labours of Richter. that considerations of another order, supported by decisive experiments, seem to enable us to appreciate his ideas pro- perly. Before Richter, and in his time also, it was supposed that the affinity of a substance was in the direct ratio of the quan- tity necessary to saturate another body. Richter compares the quantities of tartaric and of acetic acid necessary to satu- rate the same quantity of lime. He finds that more tartaric acid is necessary, and concludes that its affinity is greater, and that consequently this acid should displace acetic acid. He makes trial of this, and really it is tartaric acid which seizes the lime and displaces the acetic acid. Few examples are found more suitable than this for characterizing the dif- ficulties which are met with every day in chemistry, for here is a well-observed fact, a conclusion drawn ; an hypothesis follows, then comes the experiment which confirms it. You believe your principle well established ? By no means. An- other fact comes and overturns it. Subsequently Richter again takes up the question, and this time he clearly proves, that affinity is not exerted in the ratio of the masses which com- bine.— Vol. x. p. 187-195. It is in the fourth volume (viertes Stuck, 1795) that Richter establishes truths which will always be reckoned amongst the most important acquisitions in the region of the exact sci- ences. He begins by researches on the capacity of saturation of hydrofluoric acid; for this he uses several bases, and does not neglect alumina. He tells us (p. 10) that he took 650 grains of very pure carbonate of alumina, which he saturated with hydrofluoric acid. Here then is what he is accused of, for carbonate of alumina does not exist ! The parenthesis, then, where he says that 1000 parts of this alumina contained 542 of pure alumina, has not been read. Nor have his calculations been followed, for he everywhere takes into account alumina at the rate of 542 parts for 1000. All of you, gentlemen, who addexperience to a general knowledge of chemistry, will know that it is very difficult, I may say almost impossible, to obtain pure alumina ; if we precipitate it from its solutions by the car- bonate of ammonia, it always retains a little of this salt, and water besides. It is only by calcination that we can obtain it really pure ; but then it becomes difficult to dissolve in acids. This, doubtless, is the reason why Richter used non-calcined alumina, and determined by a separate experiment the real amount of that earth which it contained. After having found the quantity of different bases by which 1000 parts of hydrofluoric acid were saturated, a verifi- cation is required. For this purpose he decomposes fluoride M. Hess on the Scientific Labours of Richter. 87 of calcium by sulphuric acid, and infers the quantity of lime to be found in the hydrofluate from the quantity contained in the sulphate. He thus finds by analysis, that 1000 parts of hydrofluoric acid require 1882 of lime for their saturation ; by synthesis he finds 1865 parts. After that, he finds that the same quantity of acid was saturated by 3797 parts of potash, and continues in these terms : " It has been shown (he speaks of his Stochiometrie) that the quantities, whether of alkali, or of alkaline earth, which served to saturate the same quantity of one of the three volatile* mineral acids, were in constant relation with each other." Richter then ex- amines whether the results which he has just obtained sup- port this proof: he had before found that 1000 parts of mu- riatic acid require 1107 parts of lime for perfect saturation, and 2239 of potash. For hydrofluoric acid he had obtained 1882 parts and 3797. But 1107 : 2239 sfe 188.2 : 3807, which differs very little from the result of the experiment. A happy and important discovery is not all; the consequences of it must be felt; the promptitude of intelligence must go beyond the tardiness of experience, for it is only in this future that we can be armed against all the shackles of the present. Now this is the manner in which Richter announces and extends the consequences of his experiments (vol. iv. p. 67, year 1795). When two determining {determinants) elements (i. e. two acids,) each taken at the rate of 1000 parts, are satu- rated by the substances a, b, c, d and a, |S, 7, 8, so that each time a and a, b and /3, &c. are always the same substance ; in this case the (substances) quantities a, bf c are among them- selves absolutely in the same relation as «., /3, y. This theorem of Richter's is a true touchstone for all ex- periments which relate to neutrality ; for if the results do not agree with this principle, they must be rejected without hesitation. But, he adds, although according to the announce- ment of the principle we may use relations known and deter- mined by experiment, in order to find others by calculation, it will always be useful to verify these last by the fact, for we gain by it, after having recognised certain relations, the means of verifying the numbers themselves from which we had set out, and thus to correct the little inaccuracies by which they might be affected. Richter then points out the work to be done ; but in order to feel all the importance there is in its being done with the greatest precision, it will suffice to tell you that he forms a plexus of number, which covers the entire domain of chemical researches whatever they may be, and that it is precisely from not having * By these he understood the sulphuric, nitric and muriatic acids. 88 M. Hess on the Scientific Labours of Richter. performed analysis with skill enough, that Richter remained all his life uncertain on several points. Here is certainly one of the most striking proofs of the pro- gress we owe to him. He makes analyses, and deduces a general principle from them, and from that time these same analyses are no longer sufficient for the increasing wants of the science. To set out from hence the task imposed by Richter becomes gigantic. New methods are necessary. We owe them to M. Berzelius ; it is he who executed this work with a precision very rarely equalled, and which not only has not been sur- passed, but never will be by these methods. Richter, after having established this principle, continues to apply himself to the subject; he determines the capacity of saturation of acetic acid, by lime, by magnesia, by barytes, and finds that in order to saturate 1000 parts of this acid, sup- posed anhydrous, Ca 523, Mg 405*6, Ba 1465 are necessary, which gives for the composition of these salts, According to Richter. According to Berzelius. For 100 of Ca A . . Ca 34-34. A 65*66 Ca 35-63 A 64*37 MgA..Mg28*8 71'2 Mg28*66 71*34. Ba A . . Ba 59* 4 40* 6 Ba 59* 8 40* 2 Let us observe that there is no question of alumina ; it is, says he, because he is not able to find with precision the point of saturation for this base. You therefore see a real difficulty which stops him, this combination being one of those which he is more certain of determining by calculation than by ex- periment. These researches lead Richter to the conclusion that acetic acid follows the same law as the acids before considered. He then shows that the same law is also applicable to the citric, oxalic, tartaric, formic, and several other acids. It is essential to observe, that in order thus to prove by experiment the ge- nerality of the principle which he had established, an entire series of analyses was necessary for each acid, and it will be easy to judge of the ardour and time he must have expended on these labours. But in these same works he applies his principle ; as for example, he often meets with difficulties in finding the point of saturation for carbonic acid, he sets out then from a combination which he thinks well known. There again he avoids alumina as not adapted to his object, and he selects carbonate of lime. His choice could not then fall better. He finds that 1000 parts of carbonic acid are saturated by 1373 parts of lime, which gives for 100 parts Ca 57*86 and M. Hess on the Scientific Labours o/* Richter. 89 C 42'14 ; according to Berzelius, Ca 56*29 + C 43-71. Not only does Richter not choose the carbonate of alumina, but he examines the question to discover why the carbonate of this base treated by an acid disengages less carbonic acid than another base. You see then the ambiguity that there is in this substance by no means escapes him, and he continually returns to it as an enigma. Richter, armed with so powerful a principle as that which he had discovered, could not limit the application of it to his own labours ; he also applies it to those of others, and rectifies or confirms them ; for he was, so to say, endowed with a sense more than his contemporaries. Berthollet had found, as Lavoisier says in his treatise on chemistry, that 69 parts of sulphur absorb 31 parts of oxygen to become transformed into sulphuric acid. Richter repeats the experiment and comes to a very different result. He oxidates sulphur by nitric acid ; then converts it into sulphate of lime and obtains 947 parts of this latter for 222 of sul- phur, which makes 856 parts for 201 of sulphur, whilst we admit at present 857*1 . He then greatly approaches the truth, but to deduce the composition of sulphuric acid, that of the sulphate must be known exactly. This not being sufficiently well known to him, he finds that 201 parts of sulphur absorb 227 instead of 300 of oxygen to be converted into sulphuric acid (vol. v. p. 124), which compared to Berthollet's result, is still a very beautiful approximation, since this latter had only found 90 parts instead of 300. Then he is reproached with Bergmann's researches on the sulphates of potash and barytes. They are not just, he says, for if we suppose the salts compound, as Bergmann points out, and if one of them is mixed with a neutral salt, by which it may be mutually de- composed, there will be an excess of acid or of base, which cannot happen; everyone knows that the solutions remain neutral (vol. vii. p. 94 and 95) : therefore his analyses are false. Klaproth had discovered strontian*; he describes and ana- lyses several of its salts, without attention to Richter's prin- ciples. The latter applies them and finds that the analyses of Klaproth agree with the principle, and consequently that they are exact. It is this very important discovery which has been attri- buted to Wenzel. This question therefore demands an at- tentive examination ; for, take this title from Richter, and vou make him fall back into the category of ordinary philosophers. * [Strontian was first discovered by Dr. Hope; though its discovery about the same time, or shortly after, by Klaproth, appears to have been an inde- pendent one* — Edit.] 90 M. Hess on the Scientific Labours of Richter. It is no longer a summit ; it is no longer to him that the che- mist owes the compass without which he could not navigate. Well, not only does Richter in his Stochiometrie, vol. iii. p. 285, use this principle in order to verify the results of his contemporaries, but even those of Wenzel are submitted to this test. This, it may be objected, is not a proof, for he may not have quoted the author from whom he has borrowed the idea. But I have read and re-read Wenzel, and not a word, not a trace of this idea is to be found in his work. It was possible that an edition reprinted in 1800 might be inex- act; I referred to that of 1782, and with the same result. Here however is an unexceptionable proof that the principle in question really belongs to Richter and not to Wenzel. Open Wenzel's work, and you will find at the end a chap- ter which is entitled " Applications of the laws of affinity to particular cases" (Anwendung der Lehre von der Ver- "joandtschqft der Korper auf besondere Falle). This is the manner in which Wenzel expresses himself: "In chemistry, as in every other natural science, the essential aim is to compare recognised facts in their mutual relation, in order to deduce other truths which are not perceived at first view. In the experiments above quoted, we came to a knowledge of the phaenomena which took place, by the fact of the union of two substances. We saw in what order, under what condition, and in what proportions they are combined. The greater part however of these experiments, considered singly, are not of great importance, whilst we only limit science to that. But they acquire importance as soon as we apply them properly, for their merit essentially depends upon a happy application." Let us follow Wenzel in his applications, and let us choose for this purpose § 7. There he proposes as a question to find the simplest and most advantageous manner of obtaining cry- stallized verdigris. Here is what he proposes : — the sulphate of copper and the acetate of lead are both soluble in water; if these two solutions are mixed, the sulphuric acid by virtue of its affinity for the oxide of lead will seize upon this and form an insoluble substance, which may be utilized in the arts on account of its whiteness. The liquid will contain some acetate of copper which we separate from the precipi- tate. Depending upon his analyses, Wenzel calculates the quantity of oxide of lead contained in a given quantity of acetate "of lead. He then calculates the quantity of sulphate of copper necessary to precipitate all the oxide of lead. That done, he examines the question, to learn whether the acetic acid which the oxide of lead has just left is sufficient to dis- solve all the oxide of copper which has just been left by the M. Hess on the Scientific Labours o^ Richter. 91 sulphuric acid, and always starting from his analyses, he comes to the conclusion that the acetic acid set at liberty is not suf- ficient to dissolve all the oxide of copper, and that for the quantity of copper employed, which is 124 parts, there will be found of it 9j parts mixed with the sulphate of lead as an oxide. In this case Richter, starting from his principle, would necessarily say, these analyses are false ! as he did in many cases. What does Wenzel ? he, on the contrary, concludes that after having separated the solution from the precipitate, this last must be treated with a little sulphuric acid to remove the oxide of copper. Here then is a very evident proof that Wenzel did not even suspect a similar relation to that which was discovered by Richter. Richter not merely discovers this principle, but he comprehends it in its totality; he follows it in all its consequences, and nothing can show us more fully the depths of his convictions with respect to this, than some words which are to be found in the preface to the 10th volume. " The theorems of stcechiometry," says he, " contain a neces- sity; they may be constructed and have the value of a -priori principles." These principles conduct him to new generalities. He finds that when a metal is precipitated from its solution by another metal, the quantities of oxygen necessary to preserve equal quantities of the two metals in solution, are to each other in the inverse ratio of the masses of the two metals. Further oh, he concludes, since when several metals are precipitated from solution by one another, the solution always remains neutral, it is sufficient to know the difference of weight be- tween one of these metals and its oxide, to deduce from it the quantity of oxygen which all the others contain in the state of oxide. For this it is sufficient to take a constant quantity of the same acid, for then all the metals that may be dissolved in this acid will contain the same quantity of oxygen, which will then only have to be deducted from the weight of the oxide, in order to obtain that of the metal. Richter takes sulphuric acid for a starting-point, and pre- pares a table of the composition of the metallic sulphates ; in this table the quantity of oxygen of the metal being necessarily constant, he designates it by the letter U. This is what we now designate by the letter O. Richter was then very near establishing a system of equivalents, just like that which is at present used ; for that object it was sufficient to refer all the numbers to this constant quantity U. But this simple idea had not struck him, for in another column he gives the composition of the muriates, takingjlOOO parts of muriatic acid as a starting- point ; in another column, indeed, he gives the composition of 92 M. Hess on the Scientific Labours of Richter. the nitrates, taking for starting-point 1000 parts of nitric acid. His numbers therefore varied continually, which must have kept many relations concealed from his sight. Nevertheless these tables constructed by Richter have an- other peculiarity which merits our attention. The names of metals are not found in them in writing, but the signs then used are substituted for them, as 6 manganese, $ iron, 5 zinc, ]) silver. But here signs fail him, for several metals had just been newly discovered ; these Richter expresses by the two initial letters of the name, for example, %g for chrome, Ti for titanium, Te for tellurium. Here then is the first idea of the notation so happily completed by M. Berzelius. We see Richter continually occupied with the phenomenon of neutrality. What then is the neutrality of a solution ? This is a thoi'ny question, and one to which, even at the present time, many authors answer only in an obscure and evasive manner. Neutrality, says Richter, is absolute or relative : it is absolute when the solution does not exert any reaction on test papers ; it is relative when the neutral salt nevertheless exerts an acid or alkaline action. But in this case, he says, however decided may be the reaction exerted by a metallic solution (for example the nitrate of silver), you recognize, nevertheless, that it is neutral, because the least addition of an alkali causes a precipitate which will not dissolve again with- out adding an acid. Although Richter had recognised the fact that different metals required the same quantity of oxygen in order to be dissolved in the same quantity of acid ; notwithstanding, he says, when metals become charged with oxygen without the intervention of an acid, that by no means prevents them from taking very different quantities. Richter, as we see, was not ignorant that there were different degrees of oxidation, and he employed himself in determining several of them. As, however, the works of Richter which relate to the oxides of metals are far from being very exact, let us examine an example in order to discover to what the inaccuracies met with in his determinations are to be attributed. He knew, for example, that arsenic formed two combi- nations with oxygen, arsenious acid and arsenic acid. He determines by a direct experiment the quantity of oxygen which arsenious acid takes to become converted into arsenic acid, and find's that 100 parts of acid absorb 17*2 of oxygen, which is not far distant from the real number, 16*17. He after- wards seeks to determine the quantity of oxygen which me- tallic arsenic absorbs to become converted into arsenious acid, and he finds for 100 parts of metal 15*1 parts of oxygen, de- M. Hess on the Scientific Labours of Richter. 93 viating greatly from the true number, which is 31*9. Having a false idea of the composition of arsenious acid, he neces- sarily deduces a false composition for arsenic acid. Now this is the way he obtains a number so far from the truth : he converts a given weight of regulus of arsenic into arsenic acid, and then into arseniate of lead. But instead of drawing a conclusion from the weight of this latter, he first tries to determine the quantity of arsenic acid which the precipitate should contain, and for that purpose sets out from the arseniate of magnesia, which must necessarily compromise all the re- sults ; for in order to determine the composition of that salt, he saturates a solution of arsenic acid by the carbonate of magne- sia, a salt whose composition is not always constant. Then he determines the quantity of arsenic acid from a table of density previously constructed. In this then consists Richter' s greatest fault, I will even say the only one which he has committed, but from which several others originate : he did not yet quite ap- preciate the difference which exists between a direct and an in- direct method. This is the true source of all his errors. To make amends for this, each time that he makes a direct expe- riment, he approaches very nearly to the truth ; for example, if he wished to know of how much oxygen and cobalt the oxide of this metal is formed, he determines this quantity in a direct manner, and finds for 100 parts of cobalt 26*5 of oxygen, which does not widely deviate from 27, which is the real number. But Richter distrusts himself. He tells us (vol. ix. 1798, pre- amble) that he cannot easily manipulate ; that he was never able to finish an analysis without losing something at the end of all the operations ; and that he never dared to undertake an investigation if there was any question of stcechiometrical determinations, with so small a quantity as 100 grains, but that he needed 500. This is perhaps the reason why Richter at- tached great value to the tables of density, whether for acids or for salts. A considerable part of his time too was employed in making them. At the end of each acid he gives a table in- dicating the acid contents in a solution at different degrees of density. He does the same for the salts which are most used. Richter was also much employed at different times in con- structing areometers and alcoholometers ; we still use many instruments which bear his name. It is not only when Richter treats of general questions that he merits all our attention ; he often captivates it by questions which are quite special. A few examples will suffice in order to appreciate him. We have seen that he confirms the re- searches of Klaproth on the composition of the salts of stron- tian, but, he says, my conclusions are not just unless the salt 94 M. Hess on the Scientific Labours of Richter. which I have used was pure. He had prepared this salt by dissolving the natural carbonate ; the object in question then was to know if it did not contain lime or barytes. He finds that a solution of strontian is not troubled by adding a solu- tion of ferrocyanate of potash, whilst the least portion of lime or of barytes may be discovered by this means. In its turn lime is distinguished from barytes by the solubility of its sulphate. This work has been quite forgotten, and in our time a chemist in high esteem at Berlin again takes up the question, and supported by more recent works gives absolutely the same solution of the problem which his countryman Rich- ter had given so long before (Pogg., Ann. vol. xliv. p. 445*). Richter rinds that it is difficult to prepare very concentrated nitric acid because of the great quantity decomposed by heat. Now this inconvenience is remedied by using a quantity of sulphuric acid double that necessary for decomposing the nitre. Richter proposes another means which merits our at- tention ; he adds to the nitre one-third of its weight of per- oxide of manganese, and the quantity of sulphuric acid neces- sary for decomposing the two substances. He finds that the disengagement of oxygen which accompanies the distillation of nitric acid prevents the formation of nitrous acid. It was already known in Richter's time that salts while passing from the state of solution to that of crystals, gave out heat. The same phenomenon takes place when water becomes ice ; it was therefore thought fit to indicate the analogy of the two phenomena by saying ice of crystallization, instead of water of crystallization, the term which had been used till then. Richter puts the question, whether water which is found com- bined in crystals exists in them in the state of ice or not. This is the manner in which he succeeds in solving this in- teresting question. He dissolved 1440 parts of crystallized sulphate of soda (NaS + 10H); the temperature of which was 15°*55 C. in 3405 parts of water, the temperature of which was 760,67 C. The solution obtained indicated a tempera- ture of 48°*96. Supposing that the capacity of the elements for heat remains the same, Richter finds that 1440 . 15-55 + 3405 . 76'67 —r-rz = 58'4 4845 should be the temperature of the liquid. There is therefore a lowering of temperature of 9°'44. He admits that the spe- cific heat of the liquid was 0'75, and that consequently the [* A translation of the paper (by H. Rose) here referred to will be found in Phil. Mag. S. 3. vol. xiv. p. 78.— Edit.] M. Hess on the Scientific Labours of Richter. 95 depression of temperature observed is equivalent to that which would have been produced by the fusion of 457*4 parts of ice at 0°. But as he finds that the 1440 parts of salt employed con- tain, not 457 parts of solidified water, but 803 parts, he con- cludes thence that this water had not lost as much heat as the water should necessarily have lost in order to freeze, and that consequently it is not correct to say ice of crystallization. Notwithstanding the depth of his views, Richter was not the less exposed to critical attacks which were often unjust. His replies were always not only moderate, but in general as calm as if he had discussed an uncontested subject. When M * * * makes me such a reproach, says he, I bear it without thinking myself injured; I merely believe that irony does not suit the end which criticism ought to have in view and which should be to convince. Besides, every one cannot follow an author step by step in order to judge with knowledge of the subject, for it is not sufficient, for this purpose, to turn over the leaves of a work. Several times in his prefaces Richter complains of not being read with attention. Thus to give an idea of the manner in which his views were treated, I will mention another critic (M. Fries) who thought, for example, that it was impossible to explain why the elements followed a fixed law in their relations of neutrality. To that Richter re- plies, that nature would be very poor if she were limited only to what was intelligible for him and for his criticism. Another critic asked him with more reason to give a sum- mary of his doctrine which might be comprehended by every one. Richter's fault was that he did not express himself clearly ; if circumstances had caused him to undergo the severe disci- pline of the French language, if Richter, like Lavoisier, had drawn his logic from the school of Condillac, the truths which he published would have spread with more facility, and he would have produced the same results with less labour. In the sciences, gentlemen, labour is divided into two very distinct categories ; some from their novelty and the generality of their results open a new field to investigation, and spread great truths which astonish the generation which sees them originate. These works, gentlemen, make an epoch in the history of the development of intelligence, and man is hardly ever ungrateful for this benefit. Others, sometimes as diffi- cult as the preceding ones, are but a tribute of our love for science, — a right to the esteem of our contemporaries. They pursue and extend paths already opened. They cause us to be esteemed while we live ; a certain deference surrounds us: but let us not deceive ourselves; it is but the homage which politeness imposes by the fact of our presence, for after 96 Mr. J. R. Christie on the Extension of Budan's Criterion us, a generation which passes over our grave is sufficient to cause these titles not to be remembered; the facts are quoted, the authors are forgotten. The works of Richter, as we have seen, belong to these two distinct classes, and if it is true that a few words should suffice to sum up the entire life of a celebrated man, that of Richter is altogether summed up in these words (taken from the Wis- dom of Solomon, xi. 22) which he placed as an epigraph at the head of all of his works which treat of chemical proportions: " God made all things, in measure, and number, and weight." XVI. On the Extension* of 'Budan's Criterionfor the Imaginary RootS) and a new Method of effecting the Separation of the nearly equal Roots of a numerical Equation. By James R. Christie, Esq.\ T5UDAN has shown that his criterion of the presence of imaginary roots only fails when, in the pair of roots a + /3 V* — 1, a is a positive proper fraction and /3 is less than *5, on account of the effect of his reciprocal transforma- tion being that of converting these roots to the new form -~g + 02 or ai ± & V -1» wherein ay must, in the failing case, be less than unity. In the reduced reciprocal equation these roots become and they may, as before, be shown to be imaginary unless /3j be less than *5. If we suppose a to be not greater than /3, then — — will be the least value of the fraction /3X ; but /3 is less than *5, conse- quently this value of /3X must exceed unity. It appears there- fore that, in the case of a not greater than /3, the condition upon which the failure of the criterion depends, ceases to exist in the roots as they appear in the first reduced reciprocal equa- tion. The same will hold true if a does not exceed /3 y 3, since the least value this condition allows for /3j is '5. Let us now see in what manner a. and /3 enter into the se- cond reciprocal equation. * It is proper to mention that, in 1840, I pointed out the practical ap- plication of this method, in an example which was casually brought under my notice, to my friend and colleague Mr. Davies, who considered the then crude remark as of sufficient importance to be inserted, with the example, in his last edition of Hutton's " Course of Mathematics." — J. R. C. \ Communicated by the Author. for the Imaginary Roots of an Equation, fyc. 97 Supposing that the variations (which correspond to those of the original equation whose indications of roots, real or ima- ginary, we are attempting to discover by aid of the criterion) disappear from the equation in (p +.1), the roots in the immediately preceding equation will be of the form a2 + /3* P- a« + j82 or «-p(a2+/32) + /3j/-l a2 4- |S2 ' and in the second reciprocal equation (a* + ff2) . {q - p (a2 + (?) + g S^l] which finally reduces to (1 -p a)2 + f /32 -{l-paf+p /32' Now p evidently represents the integer next less than — - — a2 + /3'2, to which, if we assume a. greater than *5, the superior limit is 2; consequently, in this case, p = 1, and the above expression becomes q-(a2 + /32) +/3 4/:=! (1 - a)2 + /32 or an + 0n */^-\, making «u = (,_a)2 + /32 and ft, - (1_a)2 + /3*. It is easily seen that /3n decreases with the value of a, and the lower limit of its value will therefore, in this case, be ™y bG Satisfiqd' When the condition of the continuity of the fluid is main-x tained, the most general supposition that can be made re- specting the directions of motion in an indefinitely small element of the fluid, is that they are normals to a surface of continued curvature, and consequently intersect at right an- gles each of two focal lines situated in the planes of greatest and least curvature. In the annexed diagram let Ox, Oy, Condition of the Rectilinear Motion of Fluids. 103 O z be the axes of rectangular coordinates, and let the coor- dinates O M, M Q, Q P of the point P be x, y, st and the coordinates O m, m q, qp of p be x + dx, y, z; so that the indefinitely small line Pp is parallel to the axis O x. Draw the straight lines P N A, p n a, in the directions of the motion at the points P, p, at a given instant. Since these points are supposed to be indefinitely near each other, they may be con- sidered to belong to the same indefinitely small element of the fluid, and consequently, by what has just been said, the lines PNA,|)nflj are ultimately normals to the same curve sur- face, and pass through two focal lines such as N n and A a. Take A, the intersection of P N A with the focal line A a, for a new origin of rectangular coordinates xp yp zt ; and let the axis A z, coincide in direction with A «, the axis A x, with A N P, and the axis Ayt be parallel to N n. Draw p s per- pendicularly on A xr Let A N = /, NP = r, and P s = r{. Also let the velocity at P be V, and that at the same time at p be V + V,. The component of the velocity at P in the direction of z being w, let the component of the velocity at p in the same direction be w + dw. Then, w = V cos Y subjecting the blood of adult mammals to the slow ac- -*-* tion of a very minute quantity of dilute acetic acid, Dr. Martin Barry states that he has observed nuclei in the cor- puscles, which he has depicted in his recent and elaborate researches on the blood (Phil. Trans., 1841, part 2). Yet it seems fair to conclude that there is an essential difference between the blood -corpuscles of mammals and those of the lower vertebrata, since the very same treatment which never fails to show the nuclei in the latter will not exhibit them in the former. This, as I have elsewhere stated (Appendix to Gerber's Anatomy, pp. 13 and 30), does not prove that the corpuscles of mammals include no central matter, although it induced me to believe that these corpuscles have no nucleus like that contained in the corpuscles of the lower vertebrate animals. When the corpuscles of the oviparous vertebrata are mixed with water, or with dilute or strong acetic acid, the nuclei are instantly exposed in the clearest manner, appearing thick, oval or spherical, and much smaller than their envelopes. Several other vegetable acids, and sulphurous acid, may be used with the same effect ; and the nuclei may also be readily shown by gently moistening with the breath some dry blood, which may be again quickly dried so as to preserve the nuclei on the slip of glass for future demonstration. But when the blood-corpuscles of Man and of other mammals, not excepting the oval discs of the Camelidae (Med.-Chir. Trans,, vol.xxiii., and Lancet, vol. ii. p. 101, 1840-41) are treated by any of the means just specified, and precisely under the same circum- stances, no similar nuclei will be observed, unless in very young embryos ; for the corpuscles of these inclose a temporary and obvious nucleus, which is probably the true analogue of the persistent nucleus of the corpuscles of the oviparous vertebrata. In the Philosophical Magazine for February 1840, (S. 3. * Communicated by the Author. No. I. will be found in p. 480 of the preceding volume. 108 Mr. Gulliver's Contributions to vol. xvi.) p. 106-107, I have noticed that the blood-discs of mammalia become smaller after the removal of their colouring matter by repeated additions of water. Thus some human corpuscles having an average diameter of j^gth of an inch, measured only yg^frth after the whole of their colouring mat- ter had been separated in this manner, when they appeared flat and pellucid, very faint, and obviously differing in size and general characters from the particles usually described as the nuclei of the blood-corpuscles. No nuclei can be discerned in these washed corpuscles, either by the aid of acids, of cor- rosive sublimate, or of iodine. The first part of the preceding observation agrees in some essential points with the results obtained by Sir E. Home (Phil. Trans., 1818, pi. viii. figs. 1, 2, and 3), Schultz (Lan- cet, 1838-39, vol. ii. p. 713), and Donne (Mandl, Anat. Mi- cros., liv. i. p. 8-9). If the colouring matter be in like manner washed com- pletely from the blood-corpuscles of the lower vertebrata, both the nuclei and envelopes will remain, the latter becoming quickly circular, and the former also after a few hours. Sub- sequently the envelopes are scarcely visible, and the colourless matter of the corpuscles, which subsides in the water, appears to be composed chiefly of the nuclei, although with the aid of iodine many of the envelopes may be seen; and these are more or less reduced in size after a few days, especially in warm weather. Corrosive sublimate affects them very feebly, although it instantly increases the opacity of the washed corpuscles of mammalia. When the former corpuscles have been kept some days in water, the envelopes become very irregular, and hardly perceptible by any means ; the size of the nuclei is diminished, and they at length break up into extremely minute molecules. Dilute muriatic acid renders the nucleus clearly visible in the blood-corpuscles of the oviparous vertebrata. If the cor- puscles of a mammal be treated with the same acid, many of them appear shrunk and puckered, notched at the edges, and granulated ; some present a distinct central spot, irregular at the margin, like a granular nucleus ; others remain smooth at the circumference, often misshapen, and generally with a dark or brilliant central part, according to the focal distance in which they are placed. The two following figures will illustrate the foregoing ob- servations. The blood-corpuscles of man, and of an adult bird, with some fibrine from the blood of the latter, are re- presented as magnified about 820 diameters. Fig. 1. Outlines of blood-corpuscles of Man. In the lower part of the figure, at A, corpuscles in pure blood from a prick of the finger : some of them, lying flat, exhibit the central the Minute Anatomy of Animals. 109 spot, which others are without ; several are seen on their Fig. 1. Fig. 2. edges collected into a pile ; of the two standing separately on their edges, one appears concavo-concave, and the other con- cavo-convex. B. The corpuscles after thirty hours' washing in cool weather, the water having been changed until the whole of the colouring matter was completely removed. These membranous bases of the discs are extremely faint; but, as shown at C, they may be rendered very distinct by corrosive sublimate. D. Appearance of fresh corpuscles quickly after treating them with dilute muriatic acid : six of them extend horizontally across the figure. Fig. 2. Blood-corpuscles and fibrine of a Goose. At A is a fresh unchanged corpuscle. B. Corpuscles after having been washed precisely in the same way as those of the man, but in colder weather ; four nuclei are seen, one of which appears to contain minuter granules or nucleoli, and another has a faint envelope. C. The washed corpuscles treated with io- dine; some minute molecules adhere to the envelopes, and the nuclei seem to contain nucleoli ; the two smaller corpus- cles had remained three or four days in the water, at which time many of the envelopes were destroyed, others made irre- gular in size and shape, and the nuclei reduced to very minute molecules. D. A fresh corpuscle treated with dilute muriatic acid. E. Two oval nuclei obtained by dilute acetic acid from fresh corpuscles, for comparison with the nuclei which appear globular after having been kept in water, as seen at B and C. F. Fibrine obtained from fresh blood by washing it in a linen bag. G. The same fibrine, in which a multitude of oval par- ticles, like the nuclei of the blood-discs, are shown by acetic acid. On the Structure of Fibrine. In the English version of Gerber's Anatomy, I have de- 110 Mr. Gulliver on the Minute Anatomy of Animals. picted organic germs, or objects resembling nucleated nuclei, in clots of fibrine. Those drawings were made from clots which were either pale and opake, or as transparent and co- lourless as the serum of the blood. I have lately examined the red portions often found towards the edges of such clots, and observed in these coloured parts a multitude of objects like the organic germs above mentioned, but tinged with the colouring matter of the blood. These ruddy bodies appeared to be merely blood-discs entangled in the fibrinous clot and al- tered in their characters ; and hence the palegerms formerly de- lineated may likewise have been blood-discs still more changed, especially as the corpuscles of the blood are regarded as cells by Schwann, and cell-nuclei by Valentin, while Dr. Barry, as the result of his interesting observations, asks how many tis- sues are there which the blood -corpuscles may not form r The corpuscles, of a yellowish or ruddy hue when highly magnified, were contained abundantly in the coloured fibrine : they were rather more irregular in shape than the free cor- puscles of the same blood, and differed especially from the latter in exhibiting nuclei when washed either with dilute or strong acetic acid, and even occasionally without the aid of any reagent. The nuclei often appeared as if flattened and with a central point, and sometimes like mere granules ; they were commonly grouped together in the centre of the cor- puscle, frequently separated, and sometimes scattered about its circumference. The following figure was made from a minute red part, magnified 800 diameters, of a large, white and very firm clot of fibrine from the heart of a woman, aged 20, who died of puerperal peritonitis and acute pleurisy. Fig. 3. Fig. 3. A. A portion of the coloured fibrinewithout any addi- tion . The corpuscles are contained in a mesh of most delicate fibrils, such as I have formerly described in clots of fibrine Mr. Baily on the Mean Density of the Earth. Ill (Gerber's Anatomy, p. 31); some of the corpuscles, just like misshapen blood-discs, are seen on their edges ; others appear mottled, and one exhibits three nuclei. Many minute circular molecules are seen in the fibrine ; they were generally from 7U.lr(jotft toTT,n^otno^an mcn m dmmeter, but their appearance has not been at all clearly preserved in the engraving. B. The same washed with dilute acetic acid ; the nuclei of the corpuscles and the minute molecules are distinctly exhibited. Several of the latter are attached to a corpuscle made very faint by the acid. In fibrine obtained by washing from the blood of the ovipa- rous vertebrata, there is also frequently an appearance of minute fibrils, as shown at F, in fig. 2; but this fibrine is chiefly characterized by its containing numerous particles similar to and probably identical with the nuclei of the blood corpuscles : these particles may often be seen in the fibrine without the addition of any reagent, and acetic acid renders them very plain, as at G in fig. 2. XIX. An Account of some Experiments with the Torsion- rod, for Determining the Mean Density of the Earth. By Francis Baily, Esq., F.R.S., Vice-President of the Royal Astronomical Society *. THE author commences his account with a short prelimi- nary history of the subject, and a reference to the previous labours of Maskelyne and Cavendish. He considers the ex- periments of Maskelyne, on the attraction of the Schehallien mountain, by no means decisive of the question ; and with re- spect to those of Cavendish, by means of the torsion-rod, he is of opinion that Cavendish's object in drawing up his me- moir was more for the purpose of exhibiting a specimen of what he considered to be an excellent method of determining this important inquiry, than of deducing a result, at that time, that should lay claim to the full confidence of the scientific world. For, Cavendish himself (who made only 23 experi- ments), in allusion to this very point, expresses a doubt on the subject, and hints at some further experiments which he had in view, for clearing up some of the irregularities which he had met with. But, as no further account of any subsequent experiments is on record, and as no trace of any new light on this subject can be found amongst Cavendish's papers, the propriety and advantage of repeating the experiments, under * From the Monthly Notices of the Royal Astronomical Society, having been read May 13 and June 10, 1842'. An abstract of Mr. Baily's preli- minary paper was given in Phil. Mag. Third Series, vol. xii. p. 233 : a notice of M. Menabrea's paper on Cavendish's Experiments will be found in vol. xix. p. 62. A translation of Laplace's memoir on the mean density of the Earth, in which Cavendish's lesults are examined, was communicated by Dr. Hutton to the First Series, vol. lvi. p. 321.— Edit. 112 Mr. Baily's Experiments with the Torsion-rod, new circumstances, and with all the improvements of modern artists, had consequently been frequently discussed amongst scientific persons: and in the year 1835 the Council of this Society appointed a Committee for the express purpose of considering the subject. No effective steps, however, were taken even by this body for carrying the measure into execu- tion till the autumn of the year 1837, when Mr. Airy, the Astronomer Royal (one of the Vice-Presidents of this Society), applied for, and obtained from his late Majesty's Government, a grant of 500/. to defray the expenses of this object. Mr. Baily having offered to undertake the laborious task of making the proposed experiments, and of computing the re- sults, the whole arrangement of the plan, and the entire exe- cution of the work, was placed at his disposal and under his control. It is somewhat singular, that, whilst this plan was in agita- tion in this country, a similar course of experiments had been actually undertaken and accomplished by M. Reich, Professor of Natural Philosophy in the Academy of Mines, at Freyberg in Saxony; an account of which was read before the German Scientific Association, which met at Prague in September 1837; and an abstract of the results was printed in the Monthly Notices of this Society, for December following*. Though the experiments are, on the whole, in good accordance with the general result obtained by Cavendish, yet they do not interfere with the plan that this Society had in contem- plation ; which was not merely to repeat the original experi- ments of Cavendish in a somewhat similar manner, but also to extend the investigation by varying the magnitude and sub- stance of the attracted balls — by trying the effect of different modes of suspension — by adopting considerable difference of temperature — and by other variations that might be suggested during the progress of the inquiry. Reich made use of one mass only, and that much inferior in weight to the two adopted by Cavendish. The weight of Reich's large ball was little more than 99 pounds avoirdupois; whilst the two spheres, used by Cavendish, weighed nearly 700 pounds. Reich's ex- periments also were (like Cavendish's) too few in number; 57 only having been made, from which fourteen results have been deduced j the mean of which makes the density of the earth equal to 5'44, almost identical with that of Cavendish. As a great portion of the apparatus, which had been ordered, was at this time actually completed, and the remainder of it in considerable progress, Mr. Baily resolved to proceed in the [* This abstract appears in Mr. Baily's preliminary paper, already re- ferred to. — Edit.] for determining the Mean Density of the "Earth. 113 inquiry, notwithstanding this apparent confirmation of Caven- dish's results. Various places were suggested, by different persons, as the most suitable and fit for performing experi- ments of this kind : but, after inspecting several situations that were proposed, and considering all the circumstances of the case, Mr. Baily at length decided to carry them on at his own house, which he considers to be not only the most convenient that he could have selected, but which he has since found to be as suitable and fit as any that could have been specially erected for the express purpose. This house stands detached from any other building, in a large garden, some distance from the street, and consists of one story only. The author then proceeds to give a description of the room in which the experiments were made, and likewise of the ap- paratus that was constructed for this special purpose. Al- though the apparatus was in a general view similar to that of Cavendish, yet in some respects it was essentially different. The great balls (or masses, as they are called) were suspended from the ceiling by Cavendish and Reich: but Mr. Baily sup- ported them, from the floor, on a plank which turned on a pivot, and suspended the small balls from the ceiling ; thus reversing the mode of operations. This method of moving the masses he considers to be a great improvement : for he says, " Nothing can exceed the ease, the steadiness, and the facility with which these large bodies are moved : and during the many thousands of times that they have been turned backwards and forwards, I have never observed the least deviation from the most per- fect accuracy. At the final close of all the experiments, the pivot turns as steadily, as freely, and as accurately as at the commencement of the operations." The small balls were also, by Cavendish and Reich, suspended by a fine wire from the ends of the torsion-rod ; whereas Mr. Baily screwed them to the ends of the torsion-rod, of which they thus formed an in- tegral and solid portion. The motion of the torsion-rod was observed by means of a reflected image of the scale, from a small mirror attached to the centre of the torsion-rod, in the manner proposed by Gauss in magnetical experiments*, and adopted by Reich. Some other alterations were likewise made in the construction and arrangement of the apparatus, to which it is unnecessary to allude more minutely on the pre- sent occasion. Mr. Baily made use occasionally of several small balls, of different sizes, and formed of different substances, with a view [* See Phil. Mag. Third Series, vol. ii. p. 296 : also Taylor's Scientific Memoirs, vol. ii. p. 31, — Edit.] Phil Mag. S. 3. Vol. 2 1 . No. 1 36. Aug. 1 842. I 114 Mr. Baily's Experiments "with the Torsion-rod of ascertaining whether the results would be affected by such a variation : these were platina, lead, zinc, glass, ivory, and hollow brass, varying from 1^ inch to 2^ inches in diameter. The mode of suspension was also diversified, with a similar view: iron, copper, brass, and silk were successively used, not only single, but also double, similar to the bifilar mode suggested by Gauss* for certain magnetical experiments. The mean weight of each of the great balls (or masses) was 2,663,282 grains, or about 380| pounds avoirdupois, as de- termined by the accurate weights and scales of the Bank of England. And the weight of each of the small balls varied from 1950 to 23,742 grains. The length of the suspension- line was 60 inches ; and the length of the torsion-rod (between the centres of the two balls affixed thereto) was nearly '80 inches. The torsion-rod was made of fine deal, of an uniform shape throughout its whole length, and weighed only about 2300 grains. Another torsion-rod was afterwards made, for some special experiments, the weight of which was nearly ten times as great : it consisted of a solid brass rod, and was oc- casionally used without any balls attached to the ends. The torsion-rod and the suspension-lines were screened by a mahogany box, constructed exactly similar in form to that used by Cavendish, but supported from the ceiling in a very firm manner, and unconnected with the floor or any other part of the surrounding apparatus. Every precaution was taken to secure the torsion-rod from the influence of any sudden or partial change of temperature ; and also to insure the sta- bility and firmness of the support to which it was attached. The author's remarks on this subject are worthy of notice : for he says, " In order to satisfy myself on this point, at the time of the original construction of the apparatus, I made various attempts to create a sensible disturbance in the mo- tion of the torsion-rod, by causing the doors to be frequently and violently slammed — by jumping heavily on the floor of the room — and also above the ceiling — and in other differ- ent ways, having a similar tendency ; but in no instance could I observe the least effect upon the lateral motion of the rod. I have also frequently tried the same experiment, when dif- ferent visitors were present, since the apparatus has been com- pleted ; and have moreover many times not only accidentally, but also designedly, made a regular series of experiments for determining the density of the earth, during the most violent storms that I have ever witnessed, when the wind has been so boisterous, and blowing in such gusts, that the house has been [* See Taylor's Scientific Memoirs, vol. ii. p. 252. — Edit.] for determining the Mean Density of the Earth. 115 shaken to its centre. But in no instance have I ever seen the least disturbance in the lateral motion of the torsion-rod, nor any difference produced in the results of the experiments. I have thought it proper to make these remarks and thus to place them on record, because some persons at first ha- zarded an opinion that the place which I had selected might not be quite adapted for experiments of so delicate a nature. But a moment's consideration will convince a person conver- sant with the subject, that no dancing motion of the suspension- line (even if it did exist) would tend to produce an irregular lateral or angular motion in the torsion-rod ; and this is the only anomalous motion we need guard against. " There is also another remarkable circumstance connected with this subject, which I think it requisite likewise here to place on record. When the torsion-rod has been in a state of repose, I have frequently shaken the torsion-box, by rapidly moving the ends backward and forward from side to side fifty or sixty times, and even more : but I could never discover, that this disturbance of the box caused the least motion in the torsion-rod, which still retained its stationary position. This experiment has been witnessed at various times by se- veral scientific persons. Yet, notwithstanding this torpid state of the torsion-rod, if the slightest change of temperature be applied near the side of the torsion -box, or if either side near the balls be sprinkled with a little spirit of wine, the tor- sion-rod is immediately put in motion and the resting-point undergoes a rapid change." Notwithstanding these favourable circumstances the author at first met with certain irregularities and discordances, which he Tound it difficult to remove ; and which appear to have been experienced also by Cavendish and Reich,— caused, as it is presumed, by variations in the temperature of the room in which the experiments were carried on. Cavendish chose an out-house in his garden at Clapham Common ; and, having constructed his apparatus tsoitJmi the building, he moved the masses by means of ropes passing through a hole in the wall, and observed the torsion-rod, by means of a telescope fixed in an ante-room on the outside. The general temperature of the interior was therefore probably uniform during the time that he was occupied in any one set of experiments : but it is scarcely to be expected that a building of this kind, and in such a situation, would preserve, the same uniform tempera- ture for twenty-four successive hours : especially at the season which he selected for his operations. Reich pursued a similar plan, but under circumstances apparently more favourable ; for he selected a dark cellar, where the temperature was not 12 116 Mr. Baily's Experiments with the Torsion-rod so likely to be disturbed : and, having closed up the door, he adopted Cavendish's plan of observing the motions of the tor- sion-rod, on the outside. But, even in a situation like this, we must not expect a constant uniformity of temperature for a long period. Neither of these authors, however, has given any information on this subject ; both of them, however, met with anomalies for which they could not satisfactorily account : and, although Cavendish suspected the cause of some of those anomalies, yet he does not appear to have applied any remedy for the evil, in any of his subsequent experiments. Mr. Baily remarks, that his first experiments were tolerably regular, although the results were generally greater than those obtained either by Cavendish or Reich ; but that he soon ob- served discrepancies which convinced him that some disturb- ing force was in operation, which he had not yet contem- plated, and which he sould not discover. One of the most striking evidences of such anomaly was the remarkable circum- stance, that the arc of vibration, during one and the same ex- periment, would seldom decrease in the regular manner which it ought to pursue, if the torsion-rod were guided by an uni- foi-m influence ; and moreover, that in fact it would frequently z'wcrease, contrary to all the known laws of bodies so circum- stanced. Notwithstanding these interruptions, he not only considered it proper to continue the experiments, for some time, in the usual manner, in the hope that he might thereby eventually throw some light on the probable cause of the anomalies, and perhaps be enabled to apply a correction for the effect of their influence; but also was induced to institute several new courses of experiments, as circumstances and sug- gestions occurred, for the express purpose of elucidating the subject. The theories of electricity, magnetism, temperature, and currents of air— the influence of different modes of sus- pension by single and double wires and by double silk lines — the trial of balls composed of different substances and mag- nitudes— were successively and frequently appealed to, and various experiments made to discover their probable effect on the results. The mode of conducting the experiments was also varied in different ways, with a view of eliciting informa- tion on the point in question. Some of them were carried on like those of Cavendish, and others like those of Reich (for the methods of these two experimentalists were very different from each other), whilst many more were conducted on a plan es- sentially different from either of them. Heated balls and powerful lamps were occasionally applied near the torsion- box, with a view to raise an artificial temperature, and thus create a powerful influence ; and, on the other hand, masses for determining the Mean Density of the Earth, 117 of ice have been employed for a similar purpose. The man- ner likewise of putting the masses in motion was frequently diversified, under the hope of being enabled thereby to obtain a clue to the object of research. But the author has consi- dered it needless to proceed with a detail of these fruitless operations, which were carried on, without much interruption, for upwards of eighteen months, and amounted in number to nearly 1300 experiments. Many of these were of a mere spe- culative nature, with a view to discover the cause of the ano- malies here alluded to; but a thousand of them, at least, were more especially made for the purpose of determining the den- sity of the earth, and were eventually reduced. But the re- sults, although in many cases very consistent amongst them- selves, were upon the whole so discordant and unsatisfactory, that no confidence could be placed on the general result, as a correct value of the true object of inquiry. And, as he had pre-determined not to select merely those experiments which might appear to be the most favourable specimens, or sup- porting any particular theory, and to keep out' of view and reject the rest, he consequently abandoned the whole. During these investigations the author was frequently visited by several scientific persons who took a lively interest in the pursuit in which he was engaged, and who kindly offered him their opinion and advice on several occasions. But he re- marks, that he was principally indebted to Professor Forbes of Edinburgh, for the most satisfactory removal of the prin- cipal anomalies that he had met with. This gentleman's in- timate acquaintance with the theory of heat, and its various operations, effects, and influence, led him to agree with Caven- dish in opinion, that one source, at least, of the anomalies might arise from the radiation of heat from the masses, when they were brought up to the sides of the torsion-box : and that this might even still operate notwithstanding the inter- position of the sides of the box, and the precautions already taken. As a remedy for this influence he suggested the pro- priety of having the masses gilt, and also of procuring a gilt case, as a cover to the torsion-box, for the purpose of pre- venting the effect of radiation, from whatever source it might arise. Acting upon this advice, Mr. Baily not only caused a gilt case to be made in the manner here proposed, but also caused the torsion-box itself to be previously covered, all over, with thick flannel. These and other alterations and improve- ments having been completed, the author resolved to com- mence a 7iew series of experiments, that were likely to be thus made under more favourable auspices, for the correct deter- mination of the mean density of the earth : and it appears 118 Mr. Baily's Experiments with the Torsion-rod that the results soon convinced him that the proper mode had been taken for the removal of the principal source of discord- ance. For although, in some cases, slight discrepancies may still appear to exist, as might be expected in any inquiry that involves so delicate a system of operations, yet where the dis- cordances are of greater magnitude they seem to be confined to one class of experiments, and to depend principally on the nature and construction of the material of which the suspen- sion-line or torsion-rod is composed, and do not materially affect the general result of the whole. In fact, Mr. Baily states that he has since met with very few experiments, made in the regular mode of proceeding, that are objectionable, or that need be rejected. Every experiment therefore that has been made, under this new arrangement of the apparatus (whether good, bad, or indifferent), has been recorded and preserved; and they are all given without any reserve whatever ; it being left to the reader himself to reject or retain, at his pleasure, such as he may think fit. After these introductory remarks, the author proceeds to the several modes of carrying on the regular system of opera- tions which he had undertaken. With respect to the torsion- rod, he states that it is never at absolute rest, but is constantly in a state of vibration on its centre ; and consequently when the end of it is viewed at a distance with the telescope, it ap- pears to oscillate on each side of a mean point, called the resting-point. For, even when it is apparently in a state of complete repose, minute vibrations are always perceptible with the telescope ; and the times of performing such infinitesimal arcs correspond, in most cases, very nearly with the mean time of vibration that takes place when the torsion-rod is in full action. Mr. Baily however observes, that this resting-point is by no means permanent or stationary, and seldom remains in the same position for any length of time, even when the torsion-rod is not influenced by the approach of the masses. The extent and direction of its disturbance, as well as its rate of motion when so disturbed, are very variable, and seem to depend on causes which have not been sufficiently accounted for, but which may in some measure arise either from slight changes of temperature, or some latent alteration in the com- ponent parts of the suspension-line. These vibratory motions of the resting-point (which must be carefully distinguished from the regular vibratory changes in the position of the torsion-rod itself, caused by the near approach of the masses) do not materially affect the mean results in a series of experi- ments ; more especially if their march be regular. It is only when any sudden and considerable transition takes place, that for determining the Mean Density of the Earth. 119 a sensible and material error is likely to occur : but this sel- dom happens if due precaution has been taken to screen the torsion-box effectually. Yet the author is still of opinion that discordances sometimes arise which cannot wholly be attri- buted to change of temperature, but to some other occult in- fluence with which we are at present unacquainted. The re- gular march of the resting-point of the torsion-rod is one of the most important objects of attention ; since any considerable deviation therefrom is the source of great discordance, and therefore requires to be watched with care. The torsion force comes next under consideration. Mr. Baily justly remarks that the torsion force of a wire is that elastic power in the body, by means of which it is enabled to return to its original position, after being drawn aside by any external impulse. It varies with the substance, magnitude, and length of the wire ; but it is generally considered to be constant for the same wire, whatever be the weight suspended thereto. This, however, must be taken within certain limits, since the time of vibration (which is one of the elements for determining the force of torsion) will frequently differ very considerably without any apparent or sensible alteration in the component parts of the apparatus. For the author states that we frequently have in the same hour very considerable variations in the time of vibration, which evidently show that the force of torsion has undergone some sensible change. But this alteration in the torsion force does not appear to affect the results of the experiments, since we find that, when the time increases, the deviation is also increased in due propor- tion. The magnitude, therefore, of the force of torsion is not a necessary object of inquiry in these investigations. The only two objects requiring close attention, for the pur- pose of obtaining results from any of the experiments, are the determination of the mean resting-point of the torsion-rod, and the time of its vibration. Now, it fortunately happens that these two objects can, in all cases, be observed with the greatest ease and accuracy, however anomalous they may be; and they are never accompanied with any doubt or difficulty. There is however another subject that is required also to be . accurately ascertained in every experiment ; namely, the ex- act distance of the centre of the masses from the centre of the balls. This has been effected by means of plumb-lines, which abut against the masses, and the distances between which are measured, at every experiment, by means of a micro- scopical apparatus, carefully adjusted. From the results of the several experiments that the author has made, it would appear that single wires, of different dia- 120 Mr. Baily's Experiments with the Torsion-rod meters, give slight differences in the results. But, he states that the most discordant results occur where the double sus- pension-lines are formed of silk ; and he apprehends that these anomalies have arisen from the circumstance that all the fibres, of which the skein is composed, are not equally stretched by the different balls as they are successively attached to the torsion- rod; and that they are thus severally operated on by different forces, which consequently produces a discordancy in the re- sults. These discordances, however, appear to be generally confined within certain limits. The author then gives a detailed account of the various ex- periments that he has made, under the improved form of ap- paratus, which amount in the whole to 2153; and which were pursued and conducted in different ways, for the purpose of throwing some light on the slight discrepancies that, in spite of his care and caution, would occasionally intrude themselves. It would be impossible in an abstract like this to give a mi- nute detail of the several modes that were adopted in carrying on these operations, and which must therefore be left unex- plained till the work itself is published. But the following short synoptical view will enable the reader to form an esti- mate of the general results obtained from the different balls, according to the manner in which they have been successively suspended. The seven different balls employed are arranged, in the first column, in the order of their weight ; and the number of experiments made therewith, together with the mean resulting density therefrom, is classed in the three col- lateral columns, according as the suspension was formed of double silk lines, double metal wire, or single copper wire. The three detached series, at the bottom of the table, contain- ing 149 experiments, will be presently explained. Balls. Double silk. Double wire. Single wire. No. Density. No. Density. No. Density. 148 218 89 46 162 158 99 5-60 '5-65 5-66 5-72 573 5-78 5-82 130 145 20 170 162 5-62 5-66 5-6*8 571 570 57 162 86 92 40 20 5-58 5-59 5-56 5-60 5-61 5-79 1^-inch platina ... [ivory .... 2f-inch lead, with 2-inch lead, with b Brass rod, alone 44 49 56 5-62 5-68 5.97 It cannot be supposed, amongst such a number of expert- for determining the Mean Density of the Earth. 121 merits, prosecuted in such a variety of ways and with such different materials, that the several mean results, obtained from the individual classifications, can be of equal weight. In fact, the author himself has, in his investigations of the subject, clearly shown that some of them are entitled to more confidence than others ; and moreover that, in a few instances, there may be a fair cause for rejection. On these points how- ever there is no room for explanation in this place: and it may be sufficient here to state, that, assuming every experi- ment to be of equal weight, the mean result of the whole 2004- experiments is 5'67. Nor is there much probability that the result of this immense number of experiments will be ma- terially altered, even if those few experiments, which may appear to be affected with some source of error or discord- ance, should be wholly omitted. The author remarks that it cannot escape observation that the general mean result, obtained from these experiments, is much greater (equal to ^jth part) than that deduced either by Cavendish or Reich, who both agreed in the very same quan- tity, namely, 5*44 : but he does not assign any probable cause for this discordance. It is evident, however, from the detail which he has given of his own experiments, that perceptible differences not only arose according to the mode in which the torsion-rod was suspended, but also depended on the materials of which the suspension-lines were formed : but it is somewhat singular that none of the mean results, in any of these classi- fications, are so low as that obtained by the two experiment- alists above mentioned. In these remarks, no notice has yet been taken of the re- maining 149 experiments that have been made with the brass torsion-rod; a class of experiments that were undertaken for the express purpose of ascertaining the effect of such a mea- sure on the general result. This torsion-rod was nearly of the same weight as the two 2-inch lead balls, and about half the weight of the two 2|-inch lead balls. The experiments were made not only with each of these balls successively attached to the rod,but also with the rod alone, without anything attached thereto. The results show that the attraction of the masses on the rod should be diminished about ^th part, in order to render these three several results consistent with each other, and also accordant with the same balls and the same mode of suspension, attached to the lighter wooden torsion-rods. [ 122 ] XX. Note on Mr. Earnshaw's Paper in Phil. Mag. for April 1842. By Professor Powell. To the Editors of the Philosophical Magazine and Journal. Gentlemen, T DID not happen to see your Number for April till a few days ago, or I should long before this have addressed to you the very brief remarks which I now feel called upon to offer in consequence of certain observations in a paper inserted in the Number referred to, (S. 3. vol. xx. p. 304) " On the Theory of the Dispersion of Light," by Mr. Earnshaw. I am truly glad to see that a mathematician of such emi- nence has felt interested in the subject, and has given his at- tention to what I have published upon it : there is nothing I more desire than fair discussion : no one can have read my treatise on the Dispersion, I trust, without perceiving that I am no prejudiced undulationist, and that so far from asserting that that theory has explained the dispersion, I on the con- trary expressly point out the extent to which it does apply, and the precise degree and nature of its failure* So far then Mr. Earnshaw and myself are quite agreed. But in the mode in which he sets about the more particular proof of this assertion, there are I confess several particulars which strike me as being, to say the least, extraordinary over- sights on the part of so able a mathematician, who seems to have read my treatise, though I can only imagine, too cursorily to perceive wherein it differs from certain earlier researches, on a reference to which his whole objections seem founded. More precisely : Mr. Earnshaw points out certain imper- fections in a formula which he assumes as that I have adopted for the dispersion ; he contends that this formula is theoreti- cally defective, and also that it is discordant with the results of observation ; and enormously so in the case of the more highly dispersive media. Now all this is precisely 'what I have stated in my work on Dispersion, where (in section vi.) he and your readers will find the nature of the formula fully discussed; the formula on which he has commented being avowedly but an approximate one, which applies nearly for low dispersive substances, and which I so applied in my earliest researches, but which I long since discarded for a more accurate one. This simple circum- stance then renders all his elaborate criticisms superfluous. My published volume contains my latest view of the whole subject, and supersedes all my previous researches ; while it in- vestigates the entire series of experimental results by one uni- Note on Mr. Earnshaw's paper, Phil. Mag. April 1842. 123 form and exact method derived from a formula similar indeed to that referred to by Mr. Earnshaw, but in which the very imperfections pointed out by him are expressly corrected* As to the discrepancies between observation and theory in the higher cases of dispersion, I do not consider them as nearly so serious as Mr. Earnshaw appears to do ; and this mainly from the experience I have had in ascertaining the experimental numbers, and the degree of accuracy to which they can be relied on, — for which 1 would refer to my Report presented to the British Association on refractive indices. Thus much however is clear : the formula even in the ex- treme cases agrees as well as I think can be expected with observation, provided one of the constants receive a certain em- pirical change in its value, constant for each medium. It will therefore be the next step for theory to investigate whether such a change can be justified; but all this I have stated at large in my work, at the conclusion. Mr. Earnshaw enters also upon the question of the logic of the case, and the sitfficiency of what is merely an interpola- tion ; three indices being assumed. This point again I had, I thought, fully discussed (p. 84 et seq.); at all events, the formula, in whatever manner calculation be applied to it, is surely a direct deduction from theory. In particular, the very simple form in which I have used it, is that deduced by Sir W. R. Hamilton by a highly elegant analysis directly from the principles of M.Cauchy, and to that pre-eminently gifted mathematician it appeared a sufficient basis for calculation, as was evinced by his own use of it, to which I have referred, Art. 261. Upon the whole, I will merely add an expression of my satisfaction that the subject has been taken up by Mr. Earn- shaw, and my hope that in his hands some formula will even- tually be elicited which may be found applicable to the results of observation to such an extent as to clear up the discre- pancies which hang over the existing investigations ; in which I am well satisfied to have made a first approximation, if it lead to more accurate results from the reseaixhes which I may thus have excited more able analysts to undertake. I am, Gentlemen, Your most obedient Servant, Oxford, July 8, 1842. - BaDEN PoWELL. [ 124 ] XXI. Reply to some Objections against the Tlieory of Molecu- lar Action according to Newton's Law. By the Rev. P. Kelland, M.A., F.R.SS. L. $ E., F.C.P.S., %c, Professor of Mathematics in the University of Edinburgh, late Fellow and Tutor of Queen's College, Cambridge*. Y\THEN I wrote my reply to an anonymous correspondent ** in the Phil. Mag. (S. 3. vol. xx. January 1842, p. 8), I did not contemplate extending my remarks beyond the limits of the objections before me. But finding, as well from the pri- vate communications of my friends, as from what has ap- peared in your Journal, that silence is construed into an ad- mission of the indefensibility of the Newtonian law as applied to molecular actions, I am induced most reluctantly to enter on the defence of the hypothesis. The following remarks are the substance of a paper which I read before the Philosophical Society of Cambridge in 1840, but which, from my extreme dislike to controversy, I never printed. Nor should I have now done so, but for the expressed opinion of two of the first mathematicians in Europe, whom I am proud to number amongst my friends, both of whom have united in urging me either to remove the difficulties which attend the theory, or to point out in what way they may be regarded as not subversive of its truth. It shall be my endeavour in what follows to argue with perfect candour, not against the objections so much as for the theory. I hope nothing I shall say will induce any one to imagine that I undervalue the importance, or the in- genuity of the objections themselves, or that I lightly esteem the memoirs in which they are embodied. Let it be under- stood that I do not attempt to overthrow the arguments of my opponents to any extent further than as they, if admitted, would subvert a theory in which I am deeply interested, and which, indeed, I partly originated f. Before I enter on my subject I wish to state expressly what is the hypothesis itself which I am about to defencL It is this: That bodies consist of molecules, simple or aggregated in groups, surrounded by particles ofafiuid which pervades all space. Both the former and the latter molecules are endued with attractive or repulsive forces towards each other, and each system likewise attracts or repels the particles of the other. The law of force in all cases is that of the inverse square of the distance. * Communicated by the Author. + M. Mossotti's paper was printed at Turin in 1836 j mine was read in February of the same year. [M. Mossotti's paper was scarcely known in this country, until its contents, especially as bearing upon the theory of electricity, were announced by Mr. Faraday at the Royal Institution, on the 20th of January 1837 (see Phil. Mag. S.3. vol. x. p. 84, 317) : a transla- tion of the entire paper appeared in Taylor's Scientific Memoirs, (vol. i. p. 448) on the 1st of February.— Edit.] Theory of Molecular Action according to Newton's Law. 125 In what way the alternative of attraction or repulsion is de- fined, I do not profess accurately to specify. I prefer, for the present, to consider matters of detail as open for future in- vestigation. That I may be allowed to do so it is necessary that I should premise the grounds on which I consider them as not yet satisfactorily established. Whether the molecules of matter attract or repel each other is perfectly indifferent ; I believe either hypothesis will do very well. Neither does it signify whether the particles of matter attract or repel those of the other fluid (called aether), provided it be allowed that the latter can come in contact with and rest against the former. But whether the particles of aether attract or repel each other is a question of more importance, and one which, when de- cided, will probably settle the other two. The prima facie probability is that they act by repulsion. It is argued in favour of this supposition, that were it not so, the slightest displacement which should bring two particles near each other would of necessity cause them to run together. That this argument is fallacious will appear presently, when we shall show that they would not instantaneously tend either to unite or to separate. Another argument is that when they had once come in contact they could never again be separated. This argument applies with equal force against any hypothesis of attractive particles. At the same time I do not think the arguments in favour of the hypothesis of attraction to be by any means conclusive. The popular grounds on which I rested this hypothesis (Trans. Camb. Phil. Soc. vol. vi. p. 178) can, of course, only be held as an illustration. That they are quite insufficient to build anything upon, is obvious enough ; but it is most com- pletely shown by Mr. Earnshaw in his memoir on the Nature of Molecular Forces, to which I am about to direct attention presently. (See Art. 8.) Nor is the argument deduced from an approximate estimation of the value of the function which expresses the time of vibration of a particle, at all conclusive. It will be found in my memoir (Trans. Camb. Phil. Soc. vol. vi. p. 183 and 24-1). It rests on the assumptions, first, that the principal effect is due to the particles in the immediate neigh- bourhood of that whose motion we are ihvestigating ; secondly, that the effect of the action of any particle is independent of its position relative to the direction of transmission. The former assumption is doubtless admissible to a certain extent ; the latter, I believe, not at all. The attractive nature of the particles is still further supported by an argument which I do not now regard as satisfactory. It is this: — We have good reason to suppose that the vibrations of the air are normal, in 126 Prof. Kelland's Reply to some Objections against the the production of sound ; we are certain that the particles of air act repulsively on each other : our analysis shows, that if repulsive forces produce normal vibrations, attractive forces must act to produce the transverse ones which constitute light. There are, however, two things connected with the mutual action of the particles of air, which are here left out of the account ; the one arises from the repulsion of their sur- rounding aether, the other from its pressure against them. I do not think, therefore, that anything has been offered in favour of the hypothesis of attractive forces, so strong as to induce us to reject the contrary. I would be understood rather as waiting for more evidence previous to pledging my- self to the adoption of either. The arguments, then, to which I am about to reply are arguments against the law of force. Those which I have met with are the following : — 1. That a particle placed in a medium constituted of dis- crete molecules which exert actions varying according to the law of the inverse square of the distance will not vibrate. 2. That the equilibrium of such a medium will not be stable. 3. That the principal action on a vibrating particle will be due to the remoter parts of the system ; and, 4. That the velocity of transmission will not depend on the length of the wave. 1. The first argument is brought forward by Mr. Earn- shaw in a memoir "On the Nature of Molecular Forces," printed in the Transactions of the Cambridge Philosophical Society, vol. vii. p. 97. The memoir is one of great interest, and the analytical equations are very valuable, but I cannot ad- mit the correctness of the interpretation which the author has assigned to them, in deducing " that the molecular forces which regulate the vibrations of the aether do not vary ac- cording to Newton's law of universal gravitation." The following is an outline of the argument. V is taken for the sum of each particle divided by its distance from the one which is under discussion. The coordinates of any particle m are x, y, z, whilst those of the particle attracted are^ g, h: then, as Laplace and others have shown, the forces are dV 0 . , , . . . . d2V d*V cPV —T-jTi &c., and the relation existing is -jjv + \j 0* + ~jT dg* • yi = 0 is excepted ; indeed the author expressly points out this circumstance in Art. 8. We proceed to show that this is the very case to be considered, in a medium of sym- metry. But this phrase will perhaps itself raise an objec- tion to our arguments. We hope to be excused then if we make a short digression hereupon. A medium of perfect symmetry, it has been argued, " has never been shown to exist in nature, nor is it proved even that it can exist." We reply that, most assuredly, a medium of perfect symmetry amongst detached particles cannot exist in nature. It is quite inconceivable. Those who have adopted it, have done so " fo; the sake of simplifying their equations." (Earnshaw, Phil. Mag., S. 3. vol.xx. May 1842, p. 37Q). Nor have they regarded themselves as proceeding without reasons as valid and as well founded as those on which any one process in mathematical physics is based. If it be true from experiment that it is per- fectly indifferent in what direction light passes through certain media, then is it of necessity equally true that the sensible forces are .altogether uninfluenced by direction. And more- over if it is quite the same thing whether motion takes place from right to left or from left to right, it is inconceivable that a. It is evident that the case in which -j-^ — 0, , * = 0, 128 Prof. Kelland's Reply to some Objections against the forces which depend on the excess of the action due to the right-hand direction above that due to the left can produce any sensible effect. Let me repeat that it is not geometrical symmetry which we assumed ; a cubical arrangement which we sometimes speak of by way of illustration is not an arrange- ment of geometric, symmetry. But what we do assume is a medium of mechanical symmetry; an arrangement of such a nature that all forces are independent of direction either throughout or on either side of a particle. Perhaps the word isotropc, which M. Cauchy uses, or isodynamical, might ex- press the condition better than the word symmetrical, but further than the employment of a term which is incorrect, and of illustrations which are unsatisfactory, nothing can be urged against the introduction of the hypothesis of perfect sym- metry. d2V To return to our argument. The value of , ^ is 2(*-/)*-(y-g)*-.(3-a)2 *' Zf m c • 1* Now in a medium of symmetry %m- f-i- = 2 m w *J = 2 m± r^-. d* V d* V d2 V Hence -™ = °- Similarly -j^- = 0, -j^~ = 0. Nor is it otherwise with an isotrope or isodynamical medium, whatever be its constitution. In such a medium the value of the square of the velocity of transmission of a vibration de- pends on that of the function (r3 T> 9 X 3{z-hf\ 9 n(y-g) c - /l 3(z-/*f\ or of 2^^--^- jsin9 for the velocity is independent of the direction of vibration. The equality of these two expressions gives us (x-ff . 9*(y—g) v* {z-hf . a*{y—g) Now this equality is true whatever be the position of the vibrating particle; that is, it is perfectly independent ofy—g. Consequently the portions which depend on each particular value of y— g must be separately equal to one another. This Cr_n2 (z—hY gives us 2 m - — j~- = £ m v , . In exactly the same way does it appear that 5 m (£z££ = 5 m k~g)l. Hence -5X = 0, &c. \jL V (L V tJL V * * established that -j-^pt ■ , 2 and ^ 7a are zero, in the case Theory of Molecular Action according to Newton's Law. 129 We have taken it for granted that by " a position of equili- brium" is meant the place originally occupied by a particle in its state of rest. The arguments adduced by Mr. T irn- shaw evidently require that this should be the case. d?V d?Y d2 V '■ Having shown that ■ . no , . „ , and T 7C)- are all zero, it ° djz dg* dk? follows that any argument based on the express assumption of the contrary is invalid. But now it may be urged that we have only removed the objection from one point to another. For, admitting it to be d2V d2V d2V ■^ri -jjf an(l ~IW in question, the argument against the possibility of vibration remains in full force. For " the displacements of particles placed in such positions as those here considered would not bring into action any forces of restitution, on which account the particles would not vibrate." (Earnshaw, art. 8.) This is the argument. I fear I do not rightly see the connexion between it, and the inference which follows : " it is evident therefore that the phaenomena of light and sound are not due to the motions of particles placed in such positions." If I am wrong in conjecturing the inference, I hope to be set right ; but so far as I am able to make out, it is as follows : a particle is moved, its motion calls no force into play to draw it back, therefore it will remain in its new position, and will not vi- brate. Now we reply, that before it can be inferred that the particle will not vibrate, it is necessary to show, not only that it receives no instantaneous action owing to its change of po- sition, but that it likewise exerts none on the surrounding particles. But the latter requirement is assuredly not fulfilled. The particles in advance of that which has been moved are more acted on than they were before. Motion will therefore inevitably ensue. This argument then falls to the ground. We have thus shown that the objections are based on a state of things different from that which the hypothesis requires ; and that nothing which has been said on the contrary sup- position is available against the theory. b. But were it otherwise, were we to admit the correctness of all the reasonings referred to — should we thereby be subject to the inference which has been drawn, "that a force, whether attractive or repulsive, varying , according to Newton's law, cannot possibly actuate the particles of a vibrating medium ?" (Earnshaw, Int.) By no means. The inference rests on the assumption that a particle of the aether, when disturbed, must be acted upon by forces in the line of displacement. Now Phil. Mag. S. 3. Vol. 21. No. 136. Aug. 1842. K 130 Mr. C. Hood on Changes in the Structure of Iron this assumption is never made by writers on the molecular hypothesis, nor do I know that it is requisite ; at least, before we can admit any argument based on it, we require to be shown that it is actually or virtually made in the application of the hypothesis against which the objection is raised. We are not aware that any one has attempted to show how vi- brations are generated: the question is how they are propa- gated. Now in order to the propagation of a vibration it is assuredly requisite that the force put in play by a relative series of displacements, should, on each particle, act in the line of the displacement. But this force is not a statical force ; it is due to the actions of the displaced particles, and dependent altogether on their displacement ; in a medium of symmetry, and on the Newtonian law. (See my Memoir, Trans. Camb. Phil. Soc. vii. p. 244.) The whole line of argument, therefore, is inadmissible. No objection based on the want of fulfilment of the conditions of vibration can be valued, unless it distinctly recognises all those conditions. P.S. Since writing the above, Professor Braschmann of Moscow has favoured me with a sight of his " Theory of Equilibrium," which contains M. Mossotti's views. It is written in Russ, but as the author promises me a copy of the work with manuscript translations of some of the more important passages, I hope in a future communication to pro- fit by it. XXII. On some peculiar Changes in the Internal Structure of Iron, independent of, and subsequent to, the several Pro- cesses of its Manufacture. By Charles Hood, Esq., F.R.A.S., $c*. nPHE important purposes to which iron is applied have al- -*■ ways rendered it a subject of peculiar interest ; and at no period has its importance been so general and extensive as at the present time, when its application is almost daily ex- tending, and there is scarcely anything connected with the arts, to which, either directly or indirectly, it does not in some degree contribute. My object in the present paper is to point out some peculiarities in the habitudes of iron, which appear almost wholly to have escaped the attention of scien- tific men; and which, although in some degree known to practical mechanics, have been generally considered by them as isolated facts, and not regarded as the results of a general and important law. The circumstances, however, well de- serve the serious attention of scientific men, on account of the very important consequences to which they lead. * Communicated by the Author : having been read before the Institu- tion of Civil Engineers, June 21, 1842. subsequent to its Manufacture. 131 The two great distinctions which exist in malleable wrought iron, are known by the names of " red short " and tf cold short " qualities. The former of these comprises the tough fibrous iron, which generally possesses considerable strength when cold ; the latter shows a bright crystallized fracture, and is very brittle when cold, but works ductile while hot. These distinctions are perfectly well known to all those who are conversant with the qualities of iron : but it is not gene- rally known that there are several ways by which the tough red shot iron becomes rapidly converted into the crystallized, and by this change its strength is diminished to a very great extent. The importance which attaches to this subject at the pre- sent time will not, I think, be denied. The recent accident on the Paris and Versailles Railway, by which such a lament- able sacrifice of human life has occurred, arose from the break- ing of the axle of a locomotive engine, and which axle pre- sented at the fractured parts the appearance of the large crystals which always indicate cold short and brittle iron. I believe there is no doubt, however, that this axle, although presenting such decided evidence of being at the time of this accident of the brittle cold short quality, was at no distant period tough and fibrous in the highest degree; and as the French Government have deemed the matter of sufficient im- portance to be inquired into by a special commission, I trust that some remarks on the subject will be interesting to the members of the Institution of Civil Eugineers. I propose, therefore, to show how these extraordinary and most import- ant changes occur, and shall point out some at least of the modes by which we can demonstrate the truth of this asser- tion by actual experiment. The principal causes which produce this change, are per- cussion, heat, and magnetism : and it is doubtful whether either of these means per se will produce this effect; and there appear strong reasons for supposing that generally they are all in some degree concerned in the production of the ob- served results. The most common exemplification of the effect of heat in crystallizing fibrous iron, is by breaking a wrought-iron furnace bar, which, whatever quality it was of in the first instance, will in a short time invariably be converted into crystallized iron : and by heating and rapidly cooling, by quenching with water a few times, any piece of wrought iron, the same effect may be far more speedily produced. In these cases we have at least two of the above causes in operation, — heat and magnetism. In every instance of heat- K2 132 Mr. C. Hood on Changes in the Structure of Iron ing iron to a very high temperature, it undergoes a change in its electric or magnetic condition ; for at very high tempe- ratures iron entirely loses its magnetic powers, which return as it gradually cools to a lower temperature. In the case of quenching the heated iron with water, we have a still more decisive assistance from the electric and magnetic forces ; for Sir Humphry Davy long since pointed out* that all cases of vaporization produced negative electricity in the bodies in contact with the vapour ; a fact which has lately excited a good deal of attention, in consequence of the discovery of large quantities of negative electricity in effluent steam. These results, however, are practically of but little conse- quence ; but the effects of percussion are at once various, ex- tensive, and of high importance. We shall trace these effects under several different circumstances. In the manufacture of some descriptions of hammered iron, the bar is first rolled into shape, and then one half the length of the bar is heated in a furnace and immediately taken to the tilt-hammer and hammered ; and the other end of the bar is then heated and hammered in the same manner. In order to avoid any unevenness in the bar, or any difference in its colour, where the two distinct operations have terminated, the workman frequently gives the bar a few blows with the ham- mer on that part which he first operated upon. That part of the bar has, however, by this time become comparatively cold ; and if this cooling process has proceeded too far when it receives this additional hammering, that part of the bar im- mediately becomes crystallized, and so extremely brittle that it will break to pieces by merely throwing it on the ground, though all the rest of the bar will exhibit the best and toughest quality imaginable. This change, therefore, has been pro- duced by percussion (as the primary agent), when the bar is at a lower temperature than a welding heat. We here see the effects of percussion in a very instructive form. And it must be observed that it is not the excess of hammering which pi'oduces the effect, but the absence of a sufficient degree of heat at the time the hammering takes place ; and the evil may probably be all produced by four or five blows of the hammer, if the bar happens to be of a small size. In this case we witness the combined effects of percus- sion, heat, and magnetism. When the bar is hammered at the proper temperature no such crystallization takes place, because the bar is insensible to magnetism. But as soon as the bar becomes of that lower degree of temperature at which it can be affected by magnetism, the effect of the blows it re- * Davy's Chemical Philosophy, p. 138. subsequent to its Manufacture. 133 ceives is to produce magnetic induction, and that magnetic induction and consequent polarity of its particles, when as- sisted by further vibrations from additional percussion, pro- duces a crystallized texture. For it is perfectly well known that in soft iron magnetism can be almost instantaneously pro- duced by percussion ; and it is probable that the higher the temperature of the bar at the time it receives the magnetism, the more likely will it be to allow of that re-arrangement of its molecules which would constitute the crystallization of the iron. It is not difficult to produce the same effects by repeated blows from a hand-hammer on small bars of iron ; but it ap- pears to depend upon something peculiar in the blow, which to produce the effect must occasion a complete vibration among the particles in the neighbourhood of the part which is struck. And it is remarkable that the effects of the blows in all cases seem to be confined within certain limited di- stances of the spot which receives the strokes. Mr. Charles Manby has mentioned to me a circumstance which fully bears out this statement. In the machine used for blowing air at the Beaufort Iron Works, the piston-rod of the blowing cy- linder, for a considerable time, had a very disagreeable jar in its motion, the cause of which could not be discovered. At last the piston-rod broke off quite short, and close to the piston ; and it was then discovered that the key had not pro- perly fastened the piston and the rod together. The rod at the fracture presented a very crystallized texture ; and as it was known to have been made from the very best iron, it ex- cited considerable surprise. The rod was then cut at a short distance from the fracture, and it was found to be tough and fibrous in a very high degree ; showing what I have already pointed out, that the effects of percussion generally extend only a very short distance. In fact, we might naturally ex- pect, that as the effect of vibration diminishes in proportion to the distance from the stroke which produces it, so the cry- stallization, if produced by this means, would also diminish in the same proportion. The effect of magnetism alone may also be estimated from this circumstance. The rod would of course be magnetic throughout its whole length ; this being a necessary consequence of its position, independent of other circumstances; but the necessary force of vibration among its particles only extended for a short distance, and to that extent only did the crystallization proceed. The effect of magnetism in assisting the crystallization, I think it unneces- sary to dwell upon, as the extensive use of galvanic currents in modern times has fully proved their power in crystallizing 1S4 Mr. C. Hood on Changes in the Structure of Iron some of the most refractory substances ; but by themselves they are unable to produce these effects on iron» or at least the operation must be extremely slow. Another circumstance which occurred under Mr. Manby's observation, confirms generally the preceding opinions, A small bar of good tough iron was suspended and struck con- tinuously with small hand-hammers, to keep up a constant vibration. The bar, after the experiment had been continued for some considerable time, became so extremely brittle, that it entirely fell to pieces under the light blows of the hand- hammers, presenting throughout its structure a highly cry- stallized appearance. The fracture of the axles of road vehicles of all kinds is another instance of the same kind. I have at different times examined many broken axles of common road vehicles, and I never met with one which did not present a crystallized fracture, while it is almost certain that this could not have been the original character of the iron, as they have fre- quently been used for years with much heavier loads, and at last have broken without any apparent cause, with lighter burdens and less strain than they have formerly borne. The effects, however, on the axles of road vehicles are generally extremely slow, arising, I apprehend, from the fact that, al- though they receive a great amount of vibration, they possess a very small amount of magnetism, and are not subject to a high temperature. The degree of magnetism they receive must be extremely small, from their position and their con- stant change with regard to the magnetic meridian the abs- ence of rotation, and their insulation by the wood spokes of the wheels. Whether the effects are equally slow with iron wheels used on common roads, may perhaps admit of some question. With railway axles, however, the case is very different. In every instance of a fractured railway axle, the iron has presented the same crystallized appearance ; but this effect, I think, we shall find is likely to be produced far more ra- pidly than we might at first expect, as these axles are subject to other influences, which, if the theory here stated be correct, must greatly diminish the time required to produce the change in some other cases. Unlike other axles, those used on rail- ways rotate with the wheels, and consequently must become during their rotation highly magnetic. Messrs. Barlow and Christie were the first to demonstrate the magnetism by ro- tation produced in iron, which was afterwards extended by Messrs. Herschel and Babbage to other metals generally, in verifying some experiments by M. Arago. It cannot, I think, subsequent to its Manufacture. 13$ be doubted, that all railway axles become from this cause highly magnetic during the time they are in motion, though they may not retain the magnetism permanently. But in the axles of locomotive engines we have yet another cause which may tend to increase the effect. The vaporization of water and the effluence of steam have already been stated to produce large quantities of negative electricity in the bodies in con- tact with the vapour; and Dr. Ure has shown* that negative electricity, in all ordinary cases of crystallization, instantly determines the crystalline arrangement. This of course must affect a body of iron in a different degree to that of ordinary cases of crystallization ; but still we see that the effects of these various causes all tend in one direction, producing a more rapid change in the internal structure of the iron of the axle of a locomotive engine, than occurs in almost any other case. Dr. Wollaston first pointed out that the forms in which native iron is disposed to break, are those of the regular oc- tahedron and tetrahedron, or rhomboid, consisting of these forms combined. The tough and fibrous character of wrought iron is entirely produced by art ; and we see in these changes that have been described, an effort at returning to the natural and primal form ; the crystalline structure, in fact, being the natural state of a large number of the metals ; and Sir Hum- phry Davy has shown that all those which are fusible by or- dinary means assume the form of regular crystals by slow cooling. The general conclusion to which these remarks lead us, appears, I think, to leave no doubt that there is a constant tendency in wrought-iron, under certain circumstances, to re- turn to the crystallized state; but that this crystallization is not necessarily dependent upon time for its development, but is determined solely by other circumstances, of which the principal is undoubtedly vibration. Heat, within certain li- mits, though greatly assisting the rapidity of the change, is certainly not essential to it; but magnetism, induced either by percussion or otherwise, is an essential accompaniment of the phenomena attending the change. At a recent sitting of the Academy of Sciences at Paris, M. Bosquillon made some remarks relative to the causes of the breaking of the axle on the Versailles Railroad ; and he appears to consider that this crystallization was the joint ef- fect of time and vibration, or rather, that this change only occurs after a certain period of time. From what has here been said, it will be apparent that a fixed duration of time is * Journal of Science, vol. v. p. 106. 136 Mr. C..Hood on Changes in the Structure of Iron. not an essential element in the operation ; that the change, under certain circumstances, may take place instantaneously ; and that an axle may become crystallized in an extremely short period of time, provided that vibrations of sufficient force and magnitude be communicated to it. This circum- stance would point out the necessity for preventing as much as possible all jar and percussion on railway axles. No doubt one of the great faults of both engines and carriages of every description — but particularly the latter — is their pos- sessing far too much rigidity; thus increasing the force of every blow produced by the numerous causes incidental to railway transit; by causing the whole weight of the entire body in motion to act by its momentum in consequence of the perfect rigidity of the several parts and the manner of their connection with each other, instead of such a degree of elas- ticity as would render the different parts nearly independent of one another, in the case of sudden jerks or blows ; and which rigidity must produce very great mischief, both to the road and to the machinery moving upon it. The looseness of the axles in their brasses must also be another cause which would greatly increase this evil. Although I have more particularly alluded to the change in the internal structure of iron with reference to the effects on railway axles, it need scarcely be observed that the same remarks would apply to a vast number of other cases, where iron, from being more or less exposed to similar causes of ac- tion, must be similarly acted upon. The case of railway axles appears to be of peculiar and pressing importance, well de- serving the most serious consideration of scientific men, and particularly deserving the attention of those connected with railways, or otherwise engaged in the manufacture of railway machinery, who have the means of testing the accuracy of the theory here proposed. For if the \iews I have stated be found to harmonize with the deductions of science, and to co- incide with the results of experience, they may have a very important effect upon public safety. It may be observed, on the other hand, however, that at the present time all railway axles are made infinitely stronger than would be necessary for resisting any force they would have to sustain in producing fracture, provided the iron were of the best quality ; and to this circumstance may perhaps be attributed the comparative freedom from serious accidents by broken axles. The neces- sity for resisting flexure and the effects of torsion, are reasons why railway axles never can be made of such dimensions only as would resist simple fracture ; but it would be very desi- rable to possess some accurate experiments on the strength of Prof. Lloyd on the Magnetic Disturbance of July 2 #4", 184-2. 137 wrought iron in different stages of its crystallization, as there can be no doubt that very great differences exist in this re- spect, and it is probable that in most cases, when the crystal- lization has once commenced, the continuance of the same causes which first produced it goes on continually increasing it, and thereby further reduces the cohesive strength of the iron. Earl Street, May 31, 1842. [Several samples of broken railway axles accompanied this paper, and were exhibited at the Meeting. In some of them the same axle was broken in different places, and showed that where the greatest amount of percussion had been received, the crystallization of the iron was far more extensive than in those parts where the percussion had been less.] XXIII. Notice of a remarkable Magnetic Disturbance which occurred on the 2nd and Mh of July, 184-2. By the Rev. Humphrey Lloyd, D.D., F.R.S., V.P.R.I.A., Professor of Natural Philosophy in the University of Dublin. To Richard Taylor, Esq. Dear Sir, A VERY remarkable magnetic disturbance (the most re- ■^*- mar/cable I ever witnessed) occurred in the beginning of the present month. A brief ske*tch of some of the principal features of the phenomenon, as they were observed at the Dublin Magnetical Observatory, may probably interest some of your readers. On the 2nd of July, at 6 a.m. (Gottingen mean time), the attention of one of the assistant observers (Mr. O'Neill) was arrested by the extraordinary deviation of all the magnets from their mean positions, accompanied by a large vibration; and he immediately commenced a series of observations at short intervals. The disturbance of the declination (by which I mean the deviation of the freely suspended horizontal magnet from the mean place corresponding to that horn-) then amounted to 149*2 divisions of the scale of the instrument, or 1° 47'#3 of arc, — the north end of the magnet deviating towards the west, or the declination increased. The magnet of the bifilar magneto- meter was driven beyond the limits of the scale of its colli- mator ; and the diminution of the horizontal intensity exceeded the jpth of the whole force. Both magnets were returning rapidly towards their mean positions at the moment of the first observation ; so that the epoch of the greatest change was before 6 a.m., and its amount exceeded that observed. The 138 Prof. Lloyd's Notice of a Magnetic Disturbance observations taken at the regular hours immediately prece- ding (2 and 4 a.m. Gotfingen mean time) gave no warning of the approaching change. From 6 a.m., for nearly an hour, both magnets returned rapidly, and almost uninterruptedly, towards their mean posi- tions, the declination diminishing, and the horizontal intensity increasing. The latter element reached its maximum at 6h 56m; the declination continued to decrease until 7h 12m. After this, no very marked change occurred for some time, and the extra observations were discontinued at 8h 36m. At 10 a.m. the declinometer indicated an increase of de- clination amounting to 18*6 minutes; and the extra observa- tions were resumed, and continued for an hour. By this time (11 a.m.) both instruments had attained nearly their mean positions, from which the observations taken at the regular magnetic hours next following (noon, 2 p.m. 4 p.m.) showed no variation. The extra observations were resumed at 5h 36m p.m., the bifilar magnetometer then indicating an increase of the hori- zontal intensity, amounting to "0062 of the whole. The ob- servations were continued for more than an hour, but with- out the occurrence of any very marked change. The regular observation at 10 p.m. showed a considerable decrease of declination, accompanied by a decrease of hori- zontal intensity ; and at 1 1 p.m. the extra observations were resumed, and continued, with both instruments simultaneously, until Sunday morning. In this interval another very remark- able change took place. The declination, after some irre- gular oscillations, began to increase rapidly, and reached its maximum at llh48m, the deviation from its mean value being then 28*1 minutes. It then returned with a very rapid move- ment, and in eight minutes the magnet traversed 83 divisions of the scale, or 1° of arc; after which it made some smaller oscillations of the same rapid kind. The change of the hori- zontal intensity which occurred at the same time was still more remarkable. This element increased from 1 lh 8m to 1 11* 20m ; it then rapidly diminished for 12 minutes more; in another 6 minutes it reached a second maximum (at llh 38m); and finally the magnet was driven impetuously beyond the limits of the scale in the opposite direction, the intensity reaching its minimum at llh 50m, and the disturbance exceeding the j^th of the whole intensity. The returning oscillation occupied 12 minutes more; and at 12h 2m the magnet returned to its extreme position on the opposite side, the fluctuation in this time exceeding 111 divisions of the scale. The disturbance during these two hours was characterized by the absence of all Which occurred on the 2nd and Uh of July, 1842, 139 vibratory movement, notwithstanding the magnitude of the changes. There seemed to be a faint auroral light in the N.W. hori- zon, but without streamers. When the regular observations were recommenced, on Monday the 4-th instant, the disturbing forces were found to be still in activity. At 2 and 4 a.m. the instruments showed a very considerable decrease of declination, accompanied by a great decrease of horizontal intensity. At 6 a.m. the declina- tion exceeded the mean of the hour by a still greater amount j and the horizontal intensity had also increased, though still be- low its mean value. All the magnets were then vibrating through very large arcs. The series of observations at short intervals was then begun, and continued (almost without in- terruption) for ten hours. At 6h 24ra the declination reached its maximum, the devia- tion then amounting to 43'2 minutes. The horizontal inten- sity also attained its maximum very nearly at the same mo- ment. The two elements then began to diminish rapidly and simultaneously; and between 7 and 8 a.m. there was a double minimum of both, separated by an intervening maximum, that of the horizontal intensity taking place a few minutes earlier than the other element. At 9 a.m. the disturbance was extremely rapid. The mag- nets were hurried to and fro with a violent movement; and these changes of mean position were accompanied by a large vibration, amounting in some instances (notwithstanding the copper rings) to 20 divisions of the scale. This combination of movements rendered it difficult to seize the moment of greatest deviation, or to determine its precise amount. The declination attained a minimum at 9 a.m., which was followed by a marked maximum at 91* 22m, the range of the oscillation being 29*4 minutes. There was a corresponding change of the intensity, but somewhat later in time, — the minimum occurring at 9h 14m, and the maximum at 9*1 50m; and the range amounting to *0147» The changes of declination which occurred afterwards did not present any remarkable features ; but the horizontal in- tensity, which was previously less than in its mean state, after reaching a minimum at lh 44m, suddenly increased to an amount exceeding its mean value, and reached a maximum at 2h 5m p.m. The period of this maximum was characterized by a sudden increase of the arc of vibration, as if by impulse. The intensity continued above its mean value (though with some considerable oscillations) during the remainder of the time of observation. The disturbance ceased about 5 p.m. The induction inclinometer was observed, in conjunction 140 Prof. Lloyd on the Magnetic Disturbance of July 2 Sf^ 1842. with the other two instruments ; but the observations are un- reduced, and I am therefore unprepared as yet to offer any remark respecting the changes of inclination or total intensity. It is manifest, however, even from this imperfect sketch, that this disturbance presents many features of prominent interest: 1. In the great magnitude, and marked and abrupt cha- racter of the principal changes. In both these respects the changes at 6 a.m. and 12 p.m. on the 2nd instant, afford per- haps the most interesting points of comparison of any that the system of simultaneous observation has yet furnished ; and much light may be expected to be thrown on the phaenomena by a comparison of the results which may certainly be ex- pected to arrive from the colonial observatories, as well as of those which have been probably obtained at Port Louis, in the moveable observations of the Antarctic expedition. 2. In the striking confirmation which it affords to the con- clusion of Prof. Kreil, viz. that all the greater changes are accompanied by a diminution in the horizontal component of the intensity. The whole of the day following the disturbance (July 5) was also characterized by a diminished intensity, which is also in accordance with the inductions of Prof. Kreil; but the increase of this element towards the close of the dis- turbance (in the afternoon of the 4th) is in opposition to one of his conclusions. 3. In the two classes of changes exhibited; in one of which (as on the evening of the 2nd) the disturbances from the mean position, although great and rapid, were accomplished with- out any sensible vibration of the magnets ; while in the other (as on the morning of the 4th) the vibration exceeded any ever witnessed in this observatory, since the application of the copper rings. 4. In the occurrence of great magnetic changes without any marked auroral phaenomena. The sky was clear on the night of the 2nd, during a very remarkable part of the dis- turbance, and a light was seen in the N.W., — but of a very uncertain nature, and without any of the distinguishing cha- racters of the aurora. I may observe, however, that through- out the whole of the 3rd, and the greater part of the 4th, the sky was covered during the day with a peculiar milky white- ness, apparently belonging to something distinct from and above the clouds ; and that this disappeared suddenly, and the blue sky became visible, about 5 p.m. on the 4th, when the disturbance was at an end. I could not help regarding this appearance as connected with aurora. Believe me, dear Sir, faithfully yours, Trinity College, Dublin, H. Lloyd. July 19, 1842. [ 141 ] XXIV. Proceedings of Learned Societies. GEOLOGICAL SOCIETY. [Continued from vol. xx. p. 594.] Nov. 3, A MEMOIR entitled " Supplement to a • Synopsis of the 1841. -^*- English Series of Stratified Rocks inferior to the Old Red Sandstone/ with Additional Remarks on the Relations of the Carboniferous Series and Old Red Sandstone of the British Isles," hy the Rev. Adam Sedgwick, F.G.S., Woodwardian Professor in the University of Cambridge, was begun. Nov. 1 7 . — Professor Sedgwick's paper, commenced at the preceding meeting, was concluded. The author states that his former synopsis* is now modified ; 1st, by the new classification of the stratified rocks of Devon and Corn- wall {Devonian system) ; 2ndly, by a larger knowledge of fossils de- rived from some of the groups described ; 3rdly, by new observations made during the past summer in the south of Ireland, the south- western parts of Scotland, and in the north of England. New Red Sandstone. — 1. England. — It is shown, by sections de- rived from Warwickshire, that the upper part of the new red sandstone is sometimes unconformable to the lower part, which represents the magnesian limestone and lowest division of the new red sandstone group. It is also shown that the coal-measures pass into the overlying new red sandstone series through the intervention of bands of red marl alternating with two bands of freshwater limestone, the whole beds of passage being loaded with common coal-plants. The author then discusses the sections near Whitehaven. They show no passage from the lower new red sandstone (rotheliegende) to the coal-mea- sures ; but they show that the flora of the coal-field existed appa- rently in full perfection during the period of the lower new red sand- stone : of this flora he has obtained many new specimens. He states that the additional facts lend support to the suggestion thrown out by Mr. Murchison and himself respecting the age of the coal-field on the flanks of the Hartz. 2. Scotland. — The new red sandstone of Dumfries- shire is continu- ous with that of the plains of Carlisle, and is seen overlying the coal- measures from the valley of the Esk, near Canobie, to the neighbour hood of Dumfries. Near the latter place it is in mineral structure the same with the red sandstone of Corncockle-moor, and, at both places, the red flags contain impressions of footsteps. The author therefore asserts that the red sandstone near Loch Maben (visited by Mr. Murchison and himself in 1827) was rightly placed in the new red group. The lower divisions of the new red sandstone series do not appear to range into this part of Scotland. To the north of the Galloway chain (the great southern grey wacke chain of Scotland), the new red series almost dies away, and is seen in very few parts of Scotland. The author found no traces of it between Girvan and the mouth of the Clyde. Coupling this fact * Proceedings, vol. ii. p. 675. [or Phil. Mag. S. 3. vol. xiii. p. 299.] 14-2 Geological Society. Prof. Sedgwick on the with the great development of red sandstones in many parts of the true carboniferous series of Scotland, he concludes that the highest stratified beds of Arran do not represent the new red sandstone, but (more probably) a portion of the carboniferous group. To the upper conglomerates of Arran there is however no counterpart in England ; and the exact place of the red beds which overlie them is still left in some doubt ; but these upper conglomerates may perhaps be compared with some great trappean conglomerates which are subordinate to the Scotch coal-fields. Carboniferous series. — The author briefly notices the changes in this series during its range from the northern counties of England into the basin of the Tweed, where a coal-field occurs developed after the Scotch type, and far below the great coal-field of Newcastle. He then discusses shortly the carboniferous deposits of Scotland, which are divided as follows, in descending order : — 1 . The rich coal deposits with numerous beds of coal ; in their subordinate beds of shale, ironstone, fire-clay, and fossils, presenting the closest analogies to the great English coal-fields. Their exact place in a general scale cannot however be determined, as they offer no passages, like those above noticed, into any higher formation. 2. A great group with many thin bands of carboniferous limestone, alternating with sandstone and shale; and generally with well-defined thick beds of limestone at the top of the group, so as to form the base of the most productive coal-fields. This group also contains beds of coal, but generally of inferior quality. The alternating sandstones are not unusually of a red colour. 3. Beds of red sandstone, shale, &c. — They undergo many modifica- tions of structure and colour, and are in some places of great thick- ness. In some of their higher portions they contain coal-plants, and even thin bands of coal; but they pass downwards by grada- tions the most insensible, and blend themselves with the old red sandstone. Examples of such passages are found on the north side of St. Abb's Head, on the north shores of the Solway Firth, and on the coast of Ayrshire. The Dumfries- shire carboniferous groups are developed after the Scotch type above described ; which is the more remarkable, as the groups on the south side of the Firth conform to the English type. Near Whitehaven there is no passage from the carboniferous lime- stone to the old red sandstone ; and the thickest beds of limestone are at the bottom, and not (as in Scotland) at the top of the calca- reous series. The author then notices the geological map of Scotland, and states that Dr. M'Culloch has not merely introduced much con- fusion by giving the mountain limestone series and the old red sandstone a common colour ; but that he has committed a great error in principle, by confounding, along a considerable part of the country bordering on the north shores of the Solway Firth, the new with the old red sandstone. Old Red Sandstone. — The author, after briefly noticing the ex- traordinary irregularity in the development of this formation in the English Stratified Rocks below the Old Red Sandstone, fyc. 143 British Isles, compares the old red conglomerates of Cumberland with those on both sides of the Galloway chain. In these localities they often form unconnected masses resting on the edges of the greywacke; but in Galloway they are not only more largely de- veloped than in the north of England, but show, as above stated, many passages into the overlying carboniferous groups. Ireland. — He then briefly notices the sections which, in the south of Ireland, connect the old red sandstone with the overlying car- boniferous deposits, and form a good passage from one formation to the other. The sequence is complete, and there is nothing to mark any interruption of the deposits. He adopts Mr. Griffith's classifi- cation, as most agreeable to the physical character of the groups and to their suites of fossils. In the south of Ireland the lower carboniferous shales (of Mr. Griffith) pass into the state of roofing- slates with a transverse clea- vage, resembling the black slates at the base of the culm measures of Devonshire. The great coal-field in the west of the island overlies the mountain limestone ; but it puts on the form of the culm mea- sures of Devon, and was formerly considered as a great transition group. These facts appear to remove a difficulty in classification which was presented by the mineral structure of the Devon culm series. The author, by way of conclusion, affirms that the Scotch and Irish sections enable us to show that no new formations can be in- terpolated between the old red sandstone and carboniferous series, inasmuch as the sequence is complete. In like manner, the sections in the Silurian country show that no member is wanting between the old red sandstone and the Ludlow rock. Hence he concludes that, from the lower divisions of the new red sandstone down to the Llandeilo flagstone, there is one continuous unbroken sequence in which no term is wanting. Hence also the argument for the true place of the Devonian system is complete. For any formation, with fossils intermediate between the carboniferous and Silurian systems, must have an intermediate position, — must therefore be on the par- allel of some part of the old red sandstone, which fills that whole intermediate position, But allowing the above sequence to be com- plete, there may still be great difficulties in fixing the lines of de- marcation by which it is to be finally subdivided. For example, the lower carboniferous limestone, and the carboniferous slates of Ire- land, appear to overlap and descend below the base line of the car- boniferous series of England : and the same remark appears to be applicable to the lowest beds of the carboniferous series of Scotland. And there are similar difficulties in determining the best base line for the old red sandstone, as appears from subsequent details. Sections of North Wales, %c. — The author next discusses two sections illustrating the structure of North Wales. One is drawn from the Menai Straits, in a direction about E.S.E., so as to cross the Berwyn chain and end in the carboniferous series near Oswestry. The other is drawn from the Berwyn chain to the carboniferous limestone range on the north side of Denbighshire. The greater 144 Geological Society. Prof. Sedgwick on the portion of the first section crosses the older beds (the Cambrian system) which strike towards the N.E. The other section intersects the upper series (Silurian system) which strike towards the N.W., passing (in some places unconformably) round the beds of the older system. From a consideration of the whole evidence the rocks are grouped in the ascending order, as follows : — 1. Chlorite slate, quartz rock, and mica slate of Anglesea and Caernarvonshire. These are placed at the base of the section, and form a distinct class ; and nothing is discovered in this part of the section which is perfectly analogous with the Skiddaw slate, or first Cumbrian group, to be after described. 2. The old slate series of Caernarvonshire and Merionethshire, alternating indefinitely with bands of porphyry and felspar rock : the group is of enormous but unknown thickness, and is bent into great undulations, the anticlinal and synclinal lines of 'which are parallel to the strike of the chain. Through wide tracts of country it is without fossils ; but at Moel Hebog, Snowdon, and Glider Fawr, encrinites, corals, and a few species of bivalves have been discovered in it. It ends with the calcareous beds which range from Bala to the neighbourhood of Dinas Mowddy. This is called the Lower Cambrian group. 3. The next group (the Upper Cambrian group) commences with the fossiliferous beds of Bala, includes all the higher portion of the Berwyns, and all the slate rocks of South Wales which are below the Silurian system. Its slate beds are less crystalline, and its general structure is more mechanical, than the preceding group, and it contains incomparably more fossils, which (though there are many extensive portions of the group without fossils) are disseminated through the more calcareous beds in great abundance. Many of the fossils are identical in species with those of the lowest divisions of the Silurian system, nor have any true positive zoological characters of the group been well ascertained. In many parts of South Wales it is separated from the Silurian system by great faults and derangements of the strata, marked by a broad band of rotten non-fossiliferous schist. At the north end of the Berwyn chain it appears to pass by insensible gradations into the lower division of the Upper system (the Caradoc sand- stone). 4. The last natural group (the Silurian system). For all details respecting this system the author refers to the abstracts of Mr. Mur- chison's papers, and to his published works. The author then describes a series of sections : — (1.) East of the Berwyns, in which the Caradoc sandstone is finely developed ; containing the Llandeilo flagstone and other cha- racteristic calcareous and shelly bands. (2.) The sections north of the Berwyns, connecting Montgo- meryshire with Denbighshire. The ascending series derived from these sections is described as follows : — (1.) A series of beds several thousand feet in thickness, and at the north end of the Berwyns apparently forming a passage English Stratified Rocks below the Old Red Sandstone, fyc. 145 between the Upper Cambrian and lowest portion of the Silurian system. (2.) Bands of calcareous slate with numerous organic remains ^>f the " Caradoc sandstone," surmounted by roofing slate. (3.) Series of flagstones, more or less calcareous, with many Or- thoceratites and two species of Cardiola, &c. ; overlaid by, and associated with, irregular masses of roofing slate with a trans- verse cleavage. (4.) Flagstones and rotten slates, many parts in an imperfect state of induration, and the whole surmounted by the carboniferous limestone. — Of the preceding section the lower part of No. 3 is identical with the series of Long Mountain in the Silurian sections of Mr. Murchison ; but No. 4 is mineralogically un- like anything he has described, although it has been found by Mr. Bowman to contain, in its highest portion, some of the fossils of the Upper Ludlow rock. It appears from these details that the Silurian system, although its subdivisions are obscure from the absence of the Wenlock and Ludlow limestones, is very fully developed in North Wales. An examination of the few Snowdonian fossils of the author gives the following results : — (1.) Impressions of corals (Turbinolopsis ?) (Cwm Idwal and Moel Hebog). (2.) Stems of Encrinites (Cwm Idwal). (3.) Orthis pecten, 0. Actonia, 0. flabellulum, 0. canalis (Snow- don and Moel Hebog). He has many fossils from different parts of the Berwyn chain ; and he believes them (as stated in a former abstract) to be nearly all known Silurian species, but they have not yet been carefully examined. He possesses also a good series of fossils from the eastern side of the Berwyns, and from portions of the more northern sec- tions ; but as the whole series is unequivocally Silurian (extending from the Llandeilo flagstone to the Upper Ludlow rocks), he has not thought it at present necessary to trouble the Society with any enumeration of species. From a review of these facts he concludes, that in the great sec- tion of North Wales there is no positive zoological distinction in the successive descending groups, however vast in thickness or di- stinct in mineral structure. It is not by the addition of new species, but by the gradual disappearance of the species in the higher groups, that the successive groups are zoologically characterized. Below the Caradoc sandstone there seems to have been very few new types of creation, as far at least as we have learnt from any positive facts in the country here described. This conclusion is nearly in accord- ance with a statement made by the author in a former paper, viz. " The difficulty of classification by organic remains increases as we descend, and is at length insurmountable ; for in the lowest stratified groups, independently of metamorphic structure, all traces of fossils gradually vanish ; and the great range of certain species through numerous successive groups, and the very irregular distri- Phil. Mag. S. 3. Vol. 2 1 . No. 1 36. Aug. 1 842. L 146 Geological Society. Prof. Sedgwick on the bution of fossils even in some of the more fossiliferous divisions, add greatly to the difficulties of establishing true definite groups even within the limits of our island. The difficulties are indefinitely in- creased in comparing the formations of remote continents. But these circumstances are compensated by the magnificent scale of development of the successive groups, and their wide geographical distribution. Taken together, they have a great unity of character ; and even in remote continents they seem to form a common base, from which we may hope to compute the whole series of secondary and tertiary deposits that surmount them." Cumbrian groups, exhibited, in ascending order, in a section from Keswick through Kendal to Kirkby Lonsdale : — 1. The group of Skiddaw Forest, &c, the lower part of which rests on the granite, and passes into a system of crystalline strata resembling the rocks of the first class in North Wales ; the upper part abounds in a fine dark glossy clay slate, interrupted here and there by beds of more mechanical structure. The whole is of great thickness, almost without calcareous matter, and without any trace of organic remains, and forms the mineral axis of the Cumbrian mountains. 2. A group essentially composed of quartzose and chloritic roof- ing slates alternating with mechanical beds of coarser structure, and also with innumerable igneous rocks (compact felspar, felspar porphyry, brecciated porphyries, &c. &c.) which partake of all the accidents of the slates. It is of enormous thickness, and rises into the highest mountains of the country ; and though chiefly developed on the south side of the preceding group (No. 1), it also appears extensively on the north side of the lower group, which thus forms a mineral axis- — a fact not yet noticed in any of the published geo- logical maps. Though abounding in calcareous matter, it has no organic remains. This group is bounded by calcareous slates, which extend from the south end of Cumberland to the neighbourhood of Shap Wells, and have been described by the author in a former paper. (See Transactions of Geological Society.) 3. The next group extends from the calcareous slates (above noticed) to the carboniferous rocks, &c. which surround and cut off the older series*. The highest part of the ascending section is shown on a line which descends to the Lune near Kirkby Lonsdale. The other sections are much less perfect. The whole group is sepa- rated, provisionally, into two divisions. • The Lower division commences with the calcareous slates above * In a geological map lately presented by the author (which professes only to be a copy of a map made by himself nearly twenty years since), he represents all the beds above the calcareous slates of one colour. He does this, because he is unable to fix the demarcations of the several divi- sions of the whole group. As he considered the whole to represent the Silurian system he wished to represent the surface by three colours ; but he found it impossible, even approximately, to represent their boundaries. And even with a simpler system of two divisions, he is unable, at present, to define correctly their line of demarcation ; nearly all the middle portions of the sections being devoid of fossils. English Stratified Rocks below the Old Red Sandstone, fyc. 1 47 mentioned*. The beds over the calcareous bands are composed of slates and flagstones, hard bands occasionally passing into thick, hard, arenaceous beds of greywacke, &c. It is supposed to end a little to the north of Kendal ; but its upper limit is not defined, and there are no distinct calcareous bands to assist in connecting it with, or sepa- rating it from, the upper division. The fossils derived from the lower portion of this division are Lower Silurian. Among the fossils in the possession of the author, which have as yet been very imperfectly examined, Mr. Lonsdale has found among the corals Catenipora, Porites, Favosites, Ptilodictya, all of known Lower Silurian species, and one or two new species. Among the shells are three species of Leptaena and five species of Orthis, all of described Caradoc sandstone species ; in addition to which there are one or two new species of Orthis. With the above are also found Atrypa affinis and A. aspera; also Terebratula bipartita. With the above occur many specimens of Tentaculites annulatus ; also several Trilobites, among which are Asaphus Powisii, Isotelus Bar- riensis, and a new Paradoxite, &c. All the above fossils are found in the calcareous slates. The Upper division is composed of arenaceous flagstone, with im- perfect slaty bands, and with beds of hard greywacke. It is gene- rally of a grey, bluish- grey, or greenish-grey colour, rarely of a red- dish colour. It has some calcareous portions, but no beds of lime- stone fit for use ; and, near Kirkby Lonsdale, ends with red fossilife- rous and flaggy beds containing concretionary limestone, which are overlaid unconformably by the marls and conglomerates of the old red sandstone. The fossils of the above group (which is of great thickness, though partially repeated by undulations) are of one type. Several species are new, e. g. two or more species of Pterinsea, &c. : but the great majority of specimens, whether from the hills south of Kendal, or from Kirkby Moor, are Upper Silurian ; or in the beds Mr. Murchison places at the base of the old red sandstone (tilestone). The following list is made out by Mr. Sowerby from what the author considers a very imperfect collection : — Terebratula nucula. Orthis lunata. Leptaena lata. Very abundant. Spirifera interlineata. Cypricardia cymbiformis. Avicula rectangularis. retroflexa. Trochus helicites. Turbo Williamsii. Natica. Turritella obsoleta. "J Very gregaria. > abun- conica. J dant. Orthoceras trochleare. Calymene Blumenbachii. Cucullsea antiqua. Bellerophon trilobatus. From the above lists we obtain this definite information, that the * When a former abstract was published, the author placed these beds on the parallel of the Bala limestone,' over which the slates of the Ber- wyns and all the Devonian slates were provisionally arranged ; but since the removal of the Devonian system to a place superior to the Silurian, the sections present no real ambiguity. The calcareous slates above described are true Lower Silurian, and not a part of any sub-Silurian group that is represented by the older rocks of South Wales, L2 ]48 Geological Society: Prof. Sedgwick on the lower division is Lower Silurian, and that the upper division ends at the very top of the Silurian system, and includes beds which have been classed with the old red sandstone — an arrangement which is natural in South Wales, but is not sanctioned by the Westmoreland sections. The want of good mineral or fossil groups to distinguish the mid- dle portion of the section, makes the real difficulty of representing the divisions on a map. The author then briefly noticed two other sections ; one from the Shap granite, through the fossiliferous slates, &c, to Howgill Fells. These, in their range southwards through Middleton Fells, &c, are placed in the upper division, though not in the highest part of it, which is described above. They contain very few fossils, but those which have been found are of the Upper Silurian system. Lastly, the author briefly mentioned the phenomena of another ascending transverse section from the western end of the calcareous slates, as follows : — (1.) Calcareous slates (Caradoc) of Milium in Cumberland. (2.) Quartzose flagstone, coarse pyritous shale and slate, &c. (3.) Roofing slates of Kirkby Jreleth. (4 .) Second band of calcareous slates, also with Lower Silurian fossils . (5.) Upper series of flags and roofing-slate extending to the neigh- bourhood of Ulverston ; and in turn overlaid by coarser beds, which, however, in a section continued to Morecambe Bay, did not show any of the upper fossil bands. Ireland and South of Scotland. — The author then shortly notices some sections in the counties of Waterford and Kerry (to which he was conducted by Mr. Griffith). They exhibit a fine sequence of true Lower Silurian rocks, but do not show their relations (at least in any section seen by the author) to the older non-fossiliferous slates of the south of Ireland. Hence, though excellent examples of a group of upper fossiliferous slates, they do not offer any help as to the number and order of the natural groups into which the great in- fra-carboniferous series may be conveniently divided. He then points out that the grouping of the older strata in the south of Ireland, now given by Mr. Griffith, is not only sanctioned by the sections, but gets rid of a great supposed anomaly, — viz. the re-appearance of the carboniferous fossils at different levels on a general descending sec- tion of the older rocks of Ireland. The author then briefly notices the fossils in the true Silurian rocks in the north of Ireland, in progress of publication by Captain Port- lock. They form an admirable series, but the sections do not appear to connect the group of rocks containing them with the older forma- tions, so as to lend much help in their subdivisions or grouping. Mourne mountains, Galloway chain, SfC. — After a few details re- specting the mineral structure, strike, altered rocks, granite veins, &c, of Downshire, the author proceeds to notice the Galloway chain (which extends from the Mull of Galloway to St. Abb's Head). Its prevailing strike, like that of the Mourne mountains, is about N.E. by E. ; and this is sometimes persistent, even in the neighbourhood English Stratified Rocks below the Old Red Sandstone, fyc. 1 49 of protruded masses of granite. It is generally made up of beds of a hard arenaceous greywacke, sometimes of a very coarse structure, sometimes finer, and occasionally passing into a good roofing slate, — generally it is without fossils ; but the Graptolites foliaceus (first noticed by Mr. Carrick Moore) occurs, though rarely, among the finer slates. In these respects the chain is analogous to that in Pembrokeshire, where the same fossil occurs in the slates below the Lower Silurian rocks of Mr. Murchison. He then notices a ridge of rocks visited by Mr. Carrick Moore and himself, which breaks out from under the carboniferous basin of Girvan- water in Ayrshire. It contains many fossils, among which Mr. Sowerby finds three or four new species of Orthis, Tentaculites, Atrypa, and one or two species of Terebratula. Near it, and probably forming a part of it, is a small mass of limestone, with many corals and some Trilobites, the latter unfortunately lost by the author. Mr. Lonsdale states that the corals are difficult and obscure, but there is a true Favosites fibrosa, probably also a Favosites spongites ; and there are, among the specimens, several small hemispherical corals which may be young Stromatopora concentrica. From this evidence he would be inclined to refer the limestone to an Upper Silurian or Devonian group. From the number of Orthidia, Mr. Sowerby would refer the fossiliferous slates to the Lower Silurian ; but the whole mass, including slates and limestone, is of small extent, and seems to form but one group, which maybe considered as Silurian. To show the position of these beds, the author gives a transverse section from the Solway Firth over the Galloway chain to the fossil group above mentioned. The groups on the section appear in the following order, beginning at the south end : — 1. Old red sandstone. 2. Greywacke of the Galloway chain. 3. Granite. 4. Greywacke of the Galloway chain on the north side of the axis. 5. Unconform- able masses of old red sandstone. 6. Coal-basin of Girvan- water. 7. Fossiliferous slates and limestone rising from under the coal series. Conclusion. — It appears, from the preceding synopsis, that there is a continuous and apparently uninterrupted sequence of deposits from the lower beds of the new red sandstone formation to the low- est known strata of England ; that beds of masses of limestone ap- pear here and there in the descending series ; and (with the excep- tion of the mountain limestone) that they are neither so continuous nor so fixed in their place as to offer any good bases for the general classification of the groups ; that the divisions into which the de- scending series may be separated often pass into one another, so as to make their demarcations doubtful or arbitrary; and that, in the lower divisions, organic remains gradually disappear. The great di- visions of the descending series hitherto ascertained are as follows : — 1. Carboniferous. — Passing in some places at its upper limits into the lower new red sandstone. 2. Old red sandstone. — Passing in its upper limits (Scotland and Ireland) into the first division, and including the slate rocks, &c, of Devon and a part of Cornwall. 3. Silurian. — Passing in its upper groups into the old red sandstone . 1 50 American Philosophical Society. All the country described by Mr. Murchison as superior to the Llan- deilo flags, separated into three groups — upper, middle, and lower. East of Berwyn chain, lower group. North of the Berwyn chain (Denbighshire), upper, middle, and lower groups ; but with a new mineral type, and without any upper bands of limestone. West- moreland : upper group largely developed, and including fossils of the tilestone ; middle group without limestone bands or fossils ; lower group with many characteristic fossils. Horton and Ingleton, mid- dle and upper groups. Ireland (Waterford and Kerry), lower group. Scotland (Ayrshire), Silurian group, but not defined. 4. Sub-Silurian, or Upper Cambrian. — The old rocks of South "Wales below the preceding division ; containing Graptolites, but no well- defined calcareous band, and very few fossils. A part of the Berwyn chain based on the Bala limestone. The upper part of the roofing slates, &c, of Cumberland, immediately under the Caradoc limestone (of Coniston, &c). Slates of Charnwood Forest? Slates of the Mourne mountains, of the Galloway chain, &c. 5. Lower Cambrian. — The great slate group of North "Wales be- low the Bala limestone. The old roofing slates of Cumberland. 6. Lower Cumbrian, or Skiddaw slate. — Slates of Skiddaw Forest, lower part metamorphic. Provisionally arranged in this place, the chlorite slates, &c, of Anglesea and Caernarvonshire. AMERICAN PHILOSOPHICAL SOCIETY. January 21, 1842. — Dr.Hare made an oral communication respect- ing a new aethereal liquid which he had succeeded in obtaining. He mentioned that he had procured, by means of hyponitrite of soda, diluted sulphuric acid and pyroxylic spirit, an aethereal liquid, in which methyl (C3 H3) might be inferred to perform the same part as aethyl (C4 H5) in hyponitrous aether. In fact, by substituting py- roxylic spirit for alcohol, this new aether was elaborated by the pro- cess for hyponitrous aether, of which he had published an account in the Society's Transactions, vol. vii. part 2. The compound which was the subject of his communication had a great resemblance to alcoholic hyponitrous aether, similarly evolved, in colour, smell and taste, although there was still a difference suffi- cient to prevent the one from being mistaken for the other. Pyroxylic spirit appeared to have a greater disposition than alcohol to combine with the aether generated from it, probably in consequence of its having less affinity for water. The boiling point appeared to be nearly the same in both of the aethers ; and in both, in consequence of the escape of an aethereal gas, an effervescence, resembling that of ebullition, was observed to take place at a lower temperature than that at which the boiling point became stationary. The aethereal gas, of which Dr. Hare had given an account in his communication re- specting hyponitrous aether, seemed to have escaped the attention of European chemists; and, even after it had been noticed by him, seemed to be overlooked by Liebig, Kane, and others, in their subse- quent publications. Dr. Hare attached the more importance to his success in producing American Philosophical Society. 151 the aether which was the subject of his communication, since, agree- ably to Liebig, no such compound exists, and it is to be inferred that efforts to produce it had hitherto failed. It was presumed that this would excite no surprise, when the difference was considered between the consequences of the reaction of nitric acid with py- roxylic spirit and with alcohol. The liquid last mentioned is now viewed as a hydrated oxide of a;thyl, while pyroxylic spirit is viewed as a hydrated oxide of methyl. When alcohol is presented to nitric acid, a reciprocal decomposition ensues. The acid loses two atoms of oxygen, which, by taking two atoms of hydrogen from a portion of the alcohol, transforms it into aldehyd ; while the hyponitrous acid, resulting inevitably from the partial deoxidizement of the nitric acid, unites with the base of the remaining part of the alcohol. But when pyroxylic spirit is pre- sented to nitric acid, this acid, without decomposition, combines with methyl the base of this hydrate ; so that, as no hyponitrous acid can be evolved, no hyponitrite can be produced. Thus, in the case of the one, there can be no aethereal hyponitrite ; in that of the other, no aethereal nitrate. Dr. Hare regretted that Liebig should not have been informed of the improved process for hyponitrous aether, to which he had referred in commencing his communication. Instead of recommending a re- sort to that process, it was advised that the fumes, resulting from the reaction of nitric acid with fecula, should be passed into alcohol, and the resulting vapour condensed by means of a tube surrounded by a freezing mixture. This process Dr. Hare had repeated, and found the product very inferior in quantity and purity to that resulting from the employment of a hyponitrite. In this process, nascent hyponitrous acid, as libe- rated from a base, is brought into contact with the hydrated oxide. In the process recommended by Liebig, evidently this contact could not take place ; since it was well known that hyponitrous acid could not be obtained by subjecting fecula and nitric acid to distillation, and condensing the aeriform products*. March 4th. — Dr. Goddard presented specimens of Daguerreotype on a surface of gilded silver, and stated that the surface of iodide of gold was more susceptible to the Daguerreotype action of light than that of the iodide of silver, that the surface of the plate might be polished without injury before the action of the iodine, and that the lights came out better than on the silver surface. April 1 . — Dr. Hare related some experiments, showing that the vapour of nascent steam, generated by the hydro-oxygen flame, was not productive of electricity. He observed that, before his late voyage to Europe, he had made some experiments in order to ascertain whether any electricity was * The process alluded to is as follows : — Seven parts of acid, eight parts of alcohol, fourteen parts of water, and fourteen of hyponitrite being pre- pared, add seven parts of water to the salt and seven to the acid, and allow the mixture to cool. The saline solution and alcohol are introduced into a tubulated retort, of which the recurved and tapering beak enters a tube, which occupies the axis, and descends through the neck of an inverted bell- 1 52 American Philosophical Society. given out by the flame of the hydro-oxygen blowpipe, or by the ele- ments of water during their conversion into steam. The unexpected electrical results, previously ascertained respect- ing high steam*, naturally gave importance to this inquiry, the re- sult of which he had no previous opportunity of communicating to the Society. Even the flame produced by means of a very powerful hydro- oxygen blowpipe was not found to be productive of electrical indica- tion, when allowed to act upon a metallic mass supported upon the canopy of an extremely delicate electroscope. As it was suggested that, the flame being a conductor, the electricity evolved might retro- cede by it to the metallic pipe, the experiment was modified in the following way: — The mixture of one part of oxygen and two of hydrogen being, as in the first instance, condensed within a mercury bottle, was made, by means of a valve cock and safety tube, to communicate, through a glass tube, with a jet pipe of platinum, a foot in length and in bore. The apparatus being thus arranged, and the cock so adjusted as to allow the gaseous mixture to escape through the jet pipe with sufficient celerity, a flame of hydrogen was applied to the outside of this pipe about the middle. By these means, the temperature being raised so as to cause the elements of water to combine, the flame was removed, the heat being sufficiently kept up by the internal com- bustion. Thus that which entered at one end of the tube as gas, came out at the other as steam. Under these circumstances, a single- leaf electrometer, more susceptible than a condensing electrometer, was not indicative of any electrical excitement, either in the insulated jet tube, or in any body on which the steam was allowed to condense. Dr. J. K. Mitchell having expressed a wish to see these experi- ments, they were repeated, with his assistance, with the same results. Dr. Hare also mentioned that he had observed an sethereal liquid to subside on the addition of pure pyroxylic spirit to an aqueous solution of hypochlorous acid, obtained by passing chlorine into water in contact with bioxide of mercury. Having separated the sether thus produced, he found it to have an agreeable and peculiar fragrance. Like oil of wine, it could not be distilled without decomposition. There was an effervescence at the temperature of 140° F. ; but the boiling point rose beyond that of a glass, so as to terminate within a tall phial. Both the tube and phial must be surrounded by ice and water. The diluted acid is then added gradually. A water-bath, blood-warm, is sufficient to cause all the aether to come over. Agreeably to another plan, the materials, previously refrigerated by ice, are introduced into a bottle, also similarly refrigerated. Under these cir- cumstances the aether soon forms a superstratum which may be separated by decantation. This last-mentioned process does not answer so well for the hyponitrite of methyl, on account of the pyroxylic spirit being prone to rise with the aether ; yet the spirit may be separated from the aether by anhydrous chloride of calcium. * [See Phil. Mag. Third Series, vol. xvii. p. 370, and various subsequent papers in that volume, and in vols, xviii. xix. xx.— Edit.] Intelligence and Miscellaneous Articles. 153 boiling water-bath. When a naked flame was applied, the aether, previously colourless, acquired a yellowish wine colour, and, by the crackling evolution of vapour, indicated decomposition. When the liquid hypochlorous acid was subjected to the process of distillation, before the addition of the spirit, an aether resulted which floated on the solution, and which appeared to differ from that obtained as first mentioned. Dr. Hare made these observations, and those previously communi- cated respecting the hyponitrite of methyl, by the aid of a small quantity of pure pyroxylic spirit, supplied to him by his friend Dr. Ure, and regretted that both ill-health and the exhaustion of his stock of spirit had prevented him from making further observations and experiments, tending to decide whether the aethers obtained, as he had described, were either or both hypochlorites, or whether mer- cury entered into the composition of the heavier aether. This there was some reason for believing ; since, when boiled to dryness at a high temperature, a reddish residuum was apparent, which being re- dissolved, and a small strip of copper immersed in the resulting so- lution, a minute deposition, apparently metallic, was observable. XXV. Intelligence and Miscellaneous Articles. FOURTH MEETING OF THE ITALIAN CONGRESS OF MEN OF SCIENCE. A CIRCULAR has arrived in England announcing that the scien- tific men of Italy will meet this year at Padua on the 15 th of September, under the presidency of Signors Nicolo da Rio and Gio- vanni Santini, both of the University of Padua. The warmest invi- tations are given to such scientific persons of all nations as may be disposed to attend the meeting. ON THE EARTHQUAKE FELT IN PARTS OF CORNWALL, ON FEBRUARY 17, 1842*. At the last annual meeting of the Royal Institution of Cornwall, a communication was read from Mr. William Hen wood, recording three shocks of earthquakes, which had been felt at different periods in the county. In addition to these, the following are mentioned in a paper, by Mr. D. Milne, * On the Shocks of Earthquakes felt in Great Britain.' 1757, July 15. — The shock of an earthquake was felt at Falmouth, at seven p.m., attended with great noise. It came from the south- west, and was heard in the mines of Cornwall at a depth of seventy fathoms. The shock extended as far east as Liskeard, and as far north as Camelford. " Several small risings as big as mole-hills were observed in the morning before the shock happened, on the sands of the beach, having a black speck in the middle of the top, as if something had issued from it. From one of the risings be- * From the Report of the Polytechnic Society of Cornwall for 1841. The particulars were collected by Mr. Robert Hunt, Secretary. 154- Intelligence and Miscellaneous Articles. tween the hollows there issued a strong gush of water, about as thick as a man's wrist. For a week before the shock the weather had been warm and sultry. In one of tbe mines the earth was felt to move with a prodigious swift and apparently horizontal tremor." — Gent.'s Mag., v. xxix. 146 ; and Transactions R.S.S.* 1759, Feb. 24. — The shock of an earthquake was felt at Liskeard. A bright aurora borealis seen in the evening. From the statements of several persons residing at Budock and at Stithians, it appears some disturbance was felt in 1836. As this paper is designed to record as correctly as possible all the circumstances connected with the phenomenon of the 17th of February, 1842, I shall without hesitation state, in the first place, the manner in which it was felt at my own residence, in Berkeley Vale, Falmouth. About twenty minutes before nine a.m., I heard a peculiar rum- bling sound, more like the moaning of the wind than thunder, which was immediately followed by a shaking of the doors and windows of the house, the whole effect lasting about half a minute. In the environs of the town of Falmouth, the noise particularly attracted attention, and although but few speak of any tremor, yet all describe it either as resembling the fall of a heavy body, or like a distant explosion. Many persons were fully persuaded a steam ves- sel had blown up in the harbour. At Penryn the disturbance was more decidedly felt than at Fal- mouth, and most persons speak of the doors of their houses shaking, and some of the earthenware rattling on the shelves : many left their houses in alarm. It has been stated that the tide rose and fell again suddenly ; such does not, however, appear to have been the case : an individual, who observed the tide-mark at the bridge at the time, says that no variation was produced. At Enys, one mile from Penryn, the shock is described by J. S. Enys, Esq., " as a noise twice quickly repeated, like a heavy weight falling and rebounding:" this gentleman also speaks distinctly of the shaking of articles in the rooms. At Ponsanooth and down the valley to Perranwharf, the shock is described by all persons as considerable, and the first impression was that the powder mills in the neighbourhood had exploded. Along this line, still extending to the north, the disturbance appears to have been equally felt. The inhabitants of the villages of Comfort and Lanner, under Cam Marth, about the junction of the granite and killas or clay-slate, left their houses, thinking that some serious explosion had occurred at the neighbouring mine ; and on the south- ern side of the granite hill, Cam Marth, the people felt a great tre- mor. An intelligent person, captain of Poldory mine, describes it thus : — " I imagined some of the empty railroad waggons had been let go at the top of the incline, and were rapidly rushing past the door of my house : my neighbour, a widow woman, ran out shriek- ing that the side of her house was coming in." In Poldory, the * We presume this is intended to refer to the Transactions of the Royal Society of Edinburgh, in which Mr. Milne's paper appeared. Intelligence and Miscellaneous Articles. 155 western part of the United Mines, the shock was felt by the men working 130 fathoms below the surface ; but it does not appear to have been noticed at all in the eastern part of these or the Consoli- dated Mines. At Tresavean mine the shock was felt at all depths. The people dwelling to the north of Cam Marth do not appear to have been conscious of anything uncommon ; the noise was heard at Tuckingmill and Pool, but was attributed to the discharge of a cannon at a great distance, so faint and indistinct was it. In the south parts of the parish of Camborne the noise was also heard, but no tremor felt. In the parish of Stithians the shock was decidedly felt, and seve- ral persons in the village, who were taking breakfast at the time, speak of their tables having been shaken, and the cups and saucers having clattered. It appears to have been felt with equal intensity in the parishes of Mabe and Constantine, perhaps more powerfully in the latter than in any other part. An intelligent correspondent, who has kindly been at some pains to procure authentic accounts, thus writes: — "On the morning of the 17th a shaking of the earth was felt in this village, accompanied by a sound resembling distant thunder. At one house, where some men were working, they left their work and ran out to know what it was that gave the shock. In another a book fell from the book- shelf to the floor. Adjoining the village, where there were some persons in bed at the time from sickness, the beds were felt to shake ; a door was even seen to fly open from the shock. At Wheal Vy- vyan mine some men working about twenty or thirty fathoms under ground also felt it very distinctly ; and one man, who was leaning against a rock at the time, still more so. My wife also felt it, and it appeared to her as if the roof of the house was falling in." At Helstone the disturbance was considerable. Mr. Moyle of that town thus describes it : — " While at breakfast, about half-past eight, I started suddenly from my chair, with the impression that a heavy truck had run suddenly down the stone steps of a passage forming a back entrance to my premises." At Nansloe, half a mile south of Helstone, the servants say the earthenware evidently clat- tered ; and the same was experienced at Trevarno, two miles north- west of the town. Captain Richards, of Wheal Vor mine, situate to the west of Helstone, writes as follows : — " The shock of the earth- quake on the 17 th was very distinctly heard and felt at this mine, 175 fathoms under the surface ; also at the 80 fathom level under the surface. It was also felt at Penhale mine 50 fathoms under the surface, and by several persons within a mile of Wheal Vor mine. It was very distinctly heard and felt near Godolphin, and in and about Great Work mine ; also at Wheal Penrose mine near Porthleaven." It does not appear to have been very evident at Porthleaven. From West Wheal Virgin, in the parish of St. Hilary, I have the following communication from Captain Henry Francis : — " A little before nine on the morning of the 17 th, some of our men at work in the 100 fathom level, in the south lode, felt a shock, and as it were a rush of air, so much so that one of the candles was put out by 156 Intelligence and Miscellaneous Articles. it, accompanied by a noise which made them think that one of our shafts had crushed in, or runned together ; but on examining with Capt. Crose, who was in the mine, we could find nothing at all amiss, or any cause for the shock." This appears to be the most westerly part at which the tremor was felt, and although the noise was heard away to the south, to- wards the Lizard, it is clear it was much diminished in force. On referring to a geological map of the county, it will be found that the greatest effects were produced near the edge of the granite mass, which extends from the north-east to the south-west, from Cam Marth to the south of Penryn. Although it was felt at Fal- mouth, Helstone, and other places which are on the clay-slate, yet all my inquiries go to show that it diminished rapidly in force, as the distance from the granite increased*. A gentleman of Helstone says, " I felt it very sensibly, and my house shook, but I experienced an effect on the sight which I always find attends electricity ;" from which he appears inclined to deem the disturbance as atmospheric. Had that been the case, it would not have been felt in the mines ; but it is not improbable that a manifestation of electricity may have attended this disturbance of the earth. ON THE BLUE COLOUR OF ULTRAMARINE. BY M. ELSNER. According to all analyses hitherto published, ultramarine is com- posed principally of soda, alumina, silica and sulphur, as shown by the following statements : — Lapis Lazuli, (Clement Desormes.) Soda 23-2 Alumina 34-8 Silica 35-8 Sulphur 31 Carbonate of lime . . 3*1 (Varrentrapp.) 9-09 31*67 45-50 0-95 Lime 3-52 0-86 Sulphuric acid .... 0-42 5-89 012 Artificial Ultramarine of Paris. 4t1^M V^^ rnanufacture (C. G. Gmelin.) (Varrentrapp.) Soda (mixed with potash) 12-063 Soda 21*47 Lime 1*546 Potash 1-75 Alumina 22-000 Lime 0*02 Silica 47-306 Alumina 23-30 Sulphuric acid 4-679 Silica 45*00 Sulphur 0-188 Sulphuric acid 3'83 Resineus substance, sul- 1 lo.oia Sulphur 1'683 phur and loss. J Iron 1-063 * Mr. Hunt here adds some remarks on the condition of the atmosphere, and the heights of the barometer and thermometer at the period of the earthquake. Intelligence and Miscellaneous Articles. 157 It appears that the analyses of Varrentrapp only, give iron as pre- sent in these substances, and which is essential to the production of the blue colour of ultramarine : lapis lazuli is well known to con- tain iron pyrites. M. Eisner has analysed the blue and green varieties of ultramarine from Nuremberg, and he found them to be composed as follows : — Blue Ultramarine. Green Ultramarine. Silica 40-0 39'9 Alumina 29*5 30-0 Soda 23-0 25-5 Sulphuric acid .... 3*4 "4 Sulphur 4-0 . : 4'6 Peroxide of iron . . 1*0 '9 100-9 101-3 These contained traces of chlorine, potash, lime and magnesia. These analyses show that there is much more sulphur present than is re- quired for the production of a simple sulphuret of iron ; this excess of sulphur can be combined only with the sodium ; and it results also from the analysis, as is^also shown by synthetical researches, that sulphuret of sodium is not less necessary than sulphuret of iron to the production of ultramarine. — Journal de Pharm. et de Chim., Avril 1842. PREPARATION OF OXICHLORIC ACID. BY M. AD.NATIVELLE. Oxichloric acid, which is so useful as a reagent, M. Nativelle re- marks, is seldom to be found in laboratories ; and he supposes this to be owing to the small quantity of it which is obtained by em- ploying the proportion of sulphuric acid usually recommended in chemical works : he gives the following process as separating the whole of the acid from the oxichlorate of potash : — Put into a glass retort 500 parts of oxichlorate of potash reduced to powder, deprived as much as possible of chlorate; add 1000 parts of sulphuric acid of specific gravity 1*845, and 100 parts of distilled water ; this small quantity of water is not indispensable, for it will be shown that, by omitting it, oxichloric acid is obtained in the crystalline state. An adopter with a long tube is to be passed into a tabulated retort, surrounded with cold water ; the apparatus must not be luted with any organic substance, for the oxichloric acid gas coming into contact with it while hot decomposes it and produces slight detonations ; when proper vessels are employed lute need not be employed, but, when required, filaments of amianthus answer the purpose. The oxichlorate is to be carefully heated ; it readily dissolves, and the fire must be regulated so as to prevent the oxichloric acid from carrying over with it too much sulphuric acid. The best method of regulating the operation is to keep below the boiling point ; but little sulphuric acid goes over, for oxichloric acid volatilizes at 284°, which is much lower than the temperature at which sulphuric acid distils. The operation is complete when the residue in the retort is transparent and colourless, or when the pro- duct drops very slowly and the temperature of the retort is nearly sufficient to volatilize sulphuric acid ; the weight of the product de- 158 Intelligence and Miscellaneous Articles. pends upon the quantity of sulphuric acid carried over ; for hy a carefully conducted operation the ingredients mentioned give about 300 parts of crude acid of the density of about 1*455 ; when the operation has been too quickly conducted the density and weight of the product is greater. In order to separate the sulphuric acid and the small quantity of chlorine which the product contains, it is to be shaken with a slight excess of a saturated solution of sulphate of silver, and the chloride of silver formed is separated by nitration; the acid is then to be put into a capacious capsule, and artificial carbonate of barytes added till all the sulphuric acid is precipitated, and even till a little oxi- chlorate of barytes is formed. The liquor now contains only oxi- chloric acid, with a little oxichlorate of barytes and of silver, and is to be distilled, in the apparatus already described, with the addition of ice, separating the first product, which is only water, and ascer- taining that the acid is coming over by test paper. The distillation is to be carried on to dryness, but taking care not to decompose the oxichlorates of barytes and silver, for then the rectified oxichloric acid might contain traces of chlorine. 'The oxichloric acid thus ob- tained is perfectly pure, colourless and transparent ; its specific gra- vity is between l-717and 1*800, and it is oleaginous like sulphuric acid ; 500 parts of oxichlorate of potash yielded 150 parts of this concentrated acid. — Journal de Pharmacie et de Chimie, June 1842. ON THE ACTION OF WATER ON LEAD. BY PROF. CHRISTISON. In a second paper on this subject, just published in the Transac- tions of the Royal Society of Edinburgh (vol. xv. part 2. p. 271), Dr. Christison states the following as the results of his entire inves- tigation : — " From the facts now detailed, together with the results of my former inquiries, the following conclusions may be drawn as to the employment of lead pipes for conducting water. " 1. Lead pipes ought not to be used for the purpose, at least where the distance is considerable, without a careful chemical ex- amination of the water to be transmitted. " 2. The risk of a dangerous impregnation of lead is greatest in the instance of the purest waters. " 3. Water which tarnishes polished lead when left at rest upon it in a glass vessel for a few hours, cannot be safely transmitted through lead pipes without certain precautions *. " 4. Water which contains less than about an 8000th of salts in solution, cannot be safely conducted in lead pipes, without certain precautions. "5. Even this proportion will prove insufficient to prevent cor- rosion, unless a considerable part of the saline matter consist of car- bonates and sulphates, especially the former. " G. So large a proportion as a 4000th, probably even a consider- * " Conversely, it is probable, though not yet proved, that, if polished lead remain untarnished or nearly so for twenty-four hours in a glass of water, the water may be safely conducted through lead pipes.'-' Meteorological Observations. 159 ably larger proportion, will be insufficient, if the salts in solution be in a great measure muriates. "7. It is, I conceive, right to add, that in all cases, even though the composition of the water seems to bring it within the conditions of safety now stated, an attentive examination should be made of the water after it has been running for a few days through the pipes. For it is not improbable that other circumstances, besides those hitherto ascertained, may regulate the preventive influence of the neutral salts. " 8. When the water is judged of a kind which is likely to attack lead pipes, or when it actually flows through them impregnated with lead, a remedy may be found either in leaving the pipes full of the water and at rest for three or four months, or by substituting for the water a weak solution of phosphate of soda in the proportion of about a 25,000th part." apothecaries' hall. On Thursday, June 23rd, Mr. Robert Warington, Secretary to the Chemical Society, and formerly assistant to the late Dr. Edward Turner, Professor of Chemistry in University College, London, was elected Chemical Operator in this establishment, in consequence of the recent lamented decease of Mr. Henry Hennell, F.R.S. METEOROLOGICAL OBSERVATIONS FOR JUNE 1842. Chiswick. — June] — 3. Very fine. 4 — 7. Hot and dry. 8 — II. Fine: hot and dry: clear at night. 12, 13. Clear and hot, thermometer as high as 90° in shade. 14. Hot and dry. 15. Fine, with clouds. 16. Overcast. 17. Over- cast and fine. 18. Heavy showers. 19. Very heavy rain. 20. Cloudy and fine. 21. Slight rain. 22, 23. Very fine. 24. Slight rain. 25. Overcast: cloudy and windy : boisterous, with rain at night. 26. Fine : cloudy : clear, with dry air at night. 27, 28. Clear and fine. 29. Hot and dry. 30. Slight rain : over- cast^: very heavy rain at night. The mean temperature of the month was 20,65 above the average. Boston. — June 1. Cloudy. 2, 3. Fine. 4. Fine : thermometer 76° two o'clock p.m. 5. Fine : rain with thunder and lightning p.m. 6 — 8. Fine. 9. Cloudy. 10 — 12. Fine. 13. Cloudy. 14. Fine : thermometer 77° eleven o'clock a.m. 15. Fine. 16,17. Cloudy. 18. Rain. 19. Cloudy: rain p.m. 20. Fine: rain p.m. 21. Cloudy: rain with thunder and lightning p.m. 22,23. Fine: rain p.m. 24. Fine. 25. Windy : rain p.m. 26, 27. Windy. 28. Cloudy. 29. Fine. 30. Cloudy. N.B. The warmest June since June 1826. Sandwich Manse, Orkney. — June 1 . Clear : shower. 2. Cloudy : clear. 3. Cloudy. 4. Cloudy : rain. 5. Clear. 6—8. Clear : fog. 9. Clear : fine. 10. Cloudy: fine. 11, 12. Clear : fine. 13. Clear : damp. 14. Damp. 15. Clear: rain. 16. Clear : shower. 17. Sleet : showers. 18. Clear. 19. Clear: fine. 20. Cloudy. 21. Cloudy : damp. 22. Rain: clear. 23. Cloudy: thunder. 24. Clear : cloudy. 25. Clear : shower. 26. Damp : clear. 27. Showers : sleet. 28. Cloudy : rain. 29. Cloudy : showers. 30. Showers : cloudy. Applegarth Manse, Dumfries-shire. — June 1. Showery. 2, 3. Fair and fine. 4. Fine: shower p.m. 5. Warm and showery. 6 — 8. Fair and fine. 9 — 11. Fair and fine: droughty. 12. Fair and fine. 13. Fair and fine: thunder. 14. Fair, but threatening change. 15. Fair till p.m.: a few drops. 16. Fair, but cloudy. 17. Some drops of rain. 18. Fair and fine. 19. Shower early a.m. 20. Showers and thunder. 21. Showers : warm. 22. Shower early a.m. 23. Heavy rain p.m. 24. Frequent showers. 25. Heavy rain. 26. Showers. 27. Showers : mackerel sky. 28. Rain all day. 29. Showers a.m. ; cleared up. 30. Fine, but cloudy. c r? 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CO OS© o ^ THE LONDON, EDINBURGH and DUBLIN PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. [THIRD SERIES.] SEPTEMBER 1842. XXVI. Chemical Examination of the Fruit of Menisper- mum Cocculus (Semina Cocculi Indici). By William Francis, Ph. Z).* lyOTWITHSTANDING the numerous investigations to -*- which the grains of this plant have been submitted, much doubt still remains respecting the constitution, and even with regard to the existence of some of the many interesting bodies said to occur in them. Boullayf, to whom we are indebted for the first exami- nation, found in them a fatty oil, stearine, yellow extractive colouring matter, picrotoxine,— to which he ascribed the properties of an alkaloid, — menispermic acid, vegetable fibre, albumen, and several of the inorganic salts usually contained in plants. They were subsequently investigated by Casaseca J, principally witn regard to the menispermic acid ; he showed that no such acid existed in them, a fact which has been con- firmed by all later researches. The same chemist, in con- junction with Lecanu§, made the fatty bodies which occur in this fruit the subject of a distinct treatise, which I shall hereafter have occasion to notice more fully. Oppermann|| and quite recently Regnaultf have published analyses of pi- crotoxine. The most complete memoir on these grains is one published by Peltier and Couerbe**. They describe in it two new alka- loids, menispermine and paramenispermine, which are said to occur in the shells, and a new acid, hypopicrotoxinic acid, and they ascribe to picrotoxine acid properties. The manner in * Communicated by the Author. f Bulletin de Pharmacie, vol. iv. : Ibid, xiifcme Annee, Fev. 1826, p. 99. § Ibid. Janv. 1826, p. 55. II Mag. fur Pkarmaofe, xxxv. p. 233. f Ann. de Ckimie et de Phys.,\xvm. p.]57. ** Ann.der Pharm.B.x.[).18\. Phil. Mag. Si 3. Vol. 21. No. 137. Sept. 1842. M 162 Mr. W. Francis's Chemical Examination of the which they arrived at their conclusions has not merely ap- peared satisfactory to few chemists, but seems rather to have created increased doubt with respect to the true constituents of these grains. Under these circumstances I was induced to subject this fruit to an entirely fresh analysis : the results of my investiga- tions I shall from time to time communicate, as soon as they are so far advanced as to be fit for publication ; in the present memoir I shall treat of the fatty substances which occur so abundantly in the Cocculus grains. I. The Fatty Substances — Stearophanic Acid. The only paper with which I am acquainted in which these substances aremadethe subjectof investigation, is theone above- mentioned by Casaseca and Lecanu. By treating the coarsely pounded grains with boiling water they obtained as extract a considerable quantity of a fatty matter, impregnated with a green colouringsubstance which reddened litmus paper: treated with strong boiling alcohol a green solution was obtained pos- sessed of acid properties, and from which on cooling were de- posited flocky masses of a neutral fat of a white colour. On evaporating this alcoholic solution they obtained a fat sub- stance, which pressed between bibulous paper afforded a nearly colourless adherent nacreous mass, easily soluble in boiling alcohol, but sparingly in cold, and which melted at 59°. From these properties the authors regarded it as margaric acid. The mass which had been imbibed by the blotting-paper was extracted with alcohol, which on evaporation left behind an oily substance of a deep green colour, which Casaseca and Lecanu considered to be oleic acid. They conclude therefore from their examination, that margaric and oleic acids occur in an uncombined state in the grains of Cocculus, and more- over a neutral fat, probably analogous to stearine. From the following experiments, however, it will be seen that this acid, which it is true occurs in large quantity in a free state in these grains, is not margaric acid, but a new acid neai'ly related to the latter in its constitution, but widely dif- fering from it in its properties ; and further, that this acid likewise occurs combined with the oxide of glyceryle, and thus constitutes the neutral fat of Casaseca and Lecanu. For this acid I propose the name of stearophanic acid, (from cTBup and tpulvopai), on account of its beautiful lustre in the crystallized state, and for the neutral fat that of ' stearophanine. When the coarsely pounded grains are digested with boil- ing alcohol (that commonly used for spirit-lamps is sufficiently Fruit o/'Menispermum Cocculus. 163 strong) and the extract concentrated by distilling off' the al- cohol, on cooling, a cake floating on the surface is obtained, which consists of a deep green- coloured smeary fat matter. If the kernels after having been removed from the outer shells are submitted to a similar treatment, the same fat mass is ob- tained, only with this difference, that it is no longer green but of a yellowish colour, proving that the green colouring matter is only contained in the outer shells. The fat mass was separated from the remainder of the extract and boiled several times with distilled water, to remove all traces of pi- crotoxine and other soluble substances. It possessed an acid reaction, and was easily saponified by boiling with a dilute solution of caustic potash. The soap, which was separated by common salt, is hard, of a green colour, and affords after decomposition by an acid a green mass which solidifies on cooling. It is very easily soluble in weak boiling alcohol ; on cooling, a portion, which however is still of a yellow co- lour, crystallizes, the solution remaining green. The solid acid thus prepared, although recry stall ized ten or twelve times, could not be obtained white; it always preserved Jts yellow tint, which was especially evident on its being melted. The filtered alcoholic liquor afforded on evaporation a dark green acid oily liquid, which could not be obtained free either from colouring matter or from solid acid. If after all the picrotoxine and colouring matter have been removed by treatment three or four times with boiling alcohol, the grains be now acted upon by aether employing the gentle heat of a sand-bath, and the filtered aethereal solution be placed in the cold, a shining white fat crystallizes slowly out of it in arborescent aggregations. It was obtained perfectly pure by dissolving it once or twice in absolute boiling alcohol, which takes up very little of it, and from which it separates on cooling in grains and flocks ; it has then a dull white co- lour and a constant melting-point. Stearophanic Acid. — The pure fat thus prepared was sapo- nified by a solution of caustic potash until it formed a per- fectly clear jelly, and then treated by salt, the solid soap dissolved in much water, and decomposed by hydrochloric acid. It collects on the surface as a colourless oil, which soon solidifies into a white crystalline mass. It was now boiled with distilled water till all the hydrochloric acid was removed, and dissolved in weak warm alcohol and filtered warm. On cooling, the acid separates in small needles, which having been dried by exposure to the air, or by pressing between bi- bulous paper, possess a strong lustre of mother-of-pearl. Its melting point is constant 68° C. ; on cooling it crystallizes in M 2 164 Mr. W. Francis's Chemical Examination of the stellate groups strongly resembling some kinds of Wavellite, and has a shining white colour. It may easily be reduced to a fine powder; it is very soluble in warm weak alcohol, from which nearly the whole quantity separates on cooling; the so- lution has strong acid properties. The acid obtained in the above manner is the hydrate ; the anhydrous acid has, according to the analyses of several of its compounds, the following composition : — Calculated for 100. 35 atoms Carbon 2654*89 78*57 68 ... Hydrogen 424-30 12*55 3 ... Oxygen 300*00 8*88 3379*19 100*00 The composition of the hydrated acid in the state in which it is separated from the salts, and likewise occurs free in the kernels, was determined in the following ultimate analyses : — i. 0*275 grm. of the hydrated acid gave 0*757 carbonic acid, and 0*312 water. II. 0*294 grm. of the hydrated acid gave 0*8054 carbonic acid, and 0*337 water, in. 0*224 grm. of the hydrated acid gave 0*613 carbonic acid, and 0*252 water, iv. 0*331 grm. of the hydrated acid gave 0*913 carbonic acid, and 0357 water. v. 0*242 grm. of the hydrated acid gave 0*667 carbonic acid, and 0*272 water. In No. i. the combustion was effected by chromate of lead, in the remainder oxide of copper was employed. No. v. is an analysis of the hydrated acid as it occurs uncombined in the grains ; it was still coloured somewhat yellow, but was quite crystalline, and had the same melting-point as the per- fectly white hydrate. The above numbers afford in 100 parts, — I. II. III. iv. v. Carbon 75*71 75*32 75*24 75*84 75*79 Hydrogen... 12*60 12*73 12*50 11*98 12*49 Oxygen 11*69 11*95 12*26 12*18 11*72 100*00 100*00 100*00 100-00 100-00 These closely approach the formula C35 H70 O4. In 100 parts. 35 atoms Carbon 2654*89 76*04 70 ... Hydrogen ... 436*78 12-51 4 ... Oxygen 400-00 11-75 3491*67 100-00 Fruit o/* Menispermum Cocculus. 165 The acid therefore contains in the state of hydrate 1 atom of water, which is replaced in the salts by one equivalent of base. StearophanateqfSoda. — This salt was prepared by digesting the pure acid with an excess of carbonate of soda. On expo- sing it to a gentle heat the carbonic acid is expelled with vio- lent ebullition, and a perfectly clear solution formed, which was evaporated to dryness in the water-bath. The finely powdered mixture was then digested with absolute alcohol, which leaves the excess of carbonate of soda undissolved : a perfectly clear solution is obtained, which however soon so- lidifies into a gelatinous mass, which, transferred to a filter and dried by exposure to the air or between folds of bibulous paper, leaves behind a crystalline tissue consisting of long prisms, with a strong nacreous lustre. This compound, when treated with a small quantity of water, forms a stiff jelly ; it is decomposed on the addition of much water into an acid crystalline salt, which settles slowly, and im- parts to the liquid an opake appearance. Several stearophanates may be prepared from this salt by double decomposition. Stearophanate of Silver. — This compound was prepared by decomposing a weak alcoholic solution of the preceding salt by a perfectly neutral solution of the nitrate of silver. The precipitate is very bulky, but it soon settles. The white co- lour which it at first possesses is only of momentary duration; it acquires a slight tint of brown. Well washed and dried, it can be exposed to light without undergoing apparently any further decomposition. It dissolves easily in a solution of caustic ammonia. i. 1*134 grm. of the salt, well dried at 100°, left after igni- tion 0*317 metallic silver, corresponding to 0*3404 oxide of silver. ii. 0*379 grain of the salt- gave 0*105 silver, corresponding to 0*1127 of the oxide. This gives in 100 parts, — 1 atom Oxide of silver. . 1 ... of Stearophanic acid Calculated. Obtained. I. II. 30*01 29*73 1451*61 30*05 3379*19 69*95 69*99 70*27 4830*80 10000 100*00 100*00 On burning with oxide of copper, — i. 0*543 grm. of the silver salt gave 1*0695 carbonic acid, and 0*433 water. ii. 0*4925 grm. of the salt gave 0*9763 carbonic acid, and 0*393 water. I. II. 54-15 5451 8*83 8-86 7-15 6-76 29-87 29-87 166 Mr. W. Francis's Chemical Examination of the III. 0'259 grm. of the salt gave 0*205 water, which reduced to 100 parts, gives According to theory. III. 35 at. Carbon 54-94 68 ... Hydrogen .... 8*78 8-83 886 8*79 3 ... Oxygen 6*23 1 ... Oxide of silver. . 3005 10000 100-00 100-00 Stearophanate of the Oxide ofJEthyle. — This salt is a solid, brownish-white, semi-transparent mass. It was formed by passing a stream of dried muriatic gas for several hours into a warm saturated alcoholic solution of the acid. After some time the aether collects upon the surface as a colourless oily fluid, which solidifies on cooling. A portion still remaining in solu- tion is obtained on the addition of water. To free it from acid it was boiled several times with a dilute solution of the carbo- nate of soda, and afterwards with water. It melts at 32° C, is very fragile, void of smell in the cold, but on being warmed acquires a slight fruity odour. It melts easily on the tongue, imparting to it a sensation of cold, and has a buttery taste : it is very volatile, but is partially decomposed on distillation. It is decomposed by potash into the stearophanate of potash and alcohol. The composition was ascertained in the following ultimate analyses : — i. 0*381 grm. of the aether gave 1*0668 carbonic acid, and 0-486 water. ii. 0*247 grm. gave 0*6925 carbonic acid, and 0*286 water. No. I. analysis was made with oxide of copper. For No. ii. I am indebted to the kindness of Dr. Lawrence Smith ; it was made with oxide of copper and chlorate of potash. i. n. Carbon . . 77*01 77*09 Hydrogen. 12*69 12*85 Oxygen . . 10*30 10'06 which agree with the formula C4 H,0O + C35 H6"8 O3. 39 Carbon . . 295840 77*11 78 Hydrogen. 491*70 12-51 4 Oxygen . . 400-00 10*38 3850*10 Stearophanine. — The mode of preparation has been described above. When the fat is extracted by pressing the grains be- tween hot plates, or by means of boiling water, it is always contaminated by the free acids, colouring matter, &c, from which it separates with great difficulty. If, on the contrary, the Fruit of Menispermum Cocculus. 167 grains are first digested several times with moderately strong alcohol, all the substances which would otherwise be taken up by the aether are removed, and the fat alone remains. In warm aether it is very easily soluble, from which it crystallizes on cooling in dendritic aggregations. It does not crystallize from alcohol, in which it is but sparingly soluble, but separates as a white powder. When perfectly pure it melts at from 35° to 36° C, does not crystallize on cooling, but shrinks together, forming a wave-like rough surface; it cannot be reduced to a powder, and strongly resembles wax. It does not saponify easily on being boiled with dilute solution of potash, but im- mediately when melted with potash and a small quantity of water. It then affords, when boiled with water, a clear solu- tion, from which acids separate the stearophanic acid. When subjected to dry distillation it afforded acroleine, a solid fat acid body, and a liquid product, but no sebacic acid; it therefore contains glycerine, but is free from oleine. Before burning it with oxide of copper it was kept for some time in the water-bath, to freeitfrom adhering traces of alcohol. The following numbers were obtained : — J. 0*329 grm. of stearophanine gave 0*919 carbonic acid, and 0 361 water. ii. 0*231 grm. gave 0*645 carbonic acid, and 0*257 water, in. 021 3 grm. gave 0*236 water. In 100 we have i. ii. in. Carbon . . 76*81 76*69 Hydrogen. 12*19 12*36 12*30 Oxygen . . 11*10 10*95 which agrees with the formula C38 H72 O4. 38 atoms Carbon. . . 2882*45 77*24 72 ... Hydrogen . 449*25 12*04 4 ... Oxygen. . . 400*00 10*72 In the present case the same formula must be admitted for the constitution of glycerine as was proposed by Mr. Stenhouse in his memoir on Palmitine*, and which has likewise been adopted by M. Marsson for that occurring in combination with Laurostearic acid in the bay berries f. According to the above analyses, stearophanine consists of 1 atom of Stearophanic acid = C^H^O3 1 ... Glycerine = C3 H4 O 1 ... Stearophanine.. = C38 H72 O4 However similar the constitution of stearophanic acid may appear to that of margaric acid, there cannot be the least doubt * Philosophical Magazine, S. 3. vol. xviii. p. 190. t Annalen der Chew., und Pharm., vol. xli. p. 329 ; see also the present Number, pp. 237, 238. 168 Mr. Gulliver's Contributions to the as to their distinctness : margaric acid melts at 60° C, the margarate of the oxide of aethyle at 22°; stearophanic acid, on the other hand, has its melting-point at 68° C, and its compound with aether at 32°. But this is more effectually proved by the splendid crystallization of the acid and of its soda salt. When compared with the very numerous pre- parations of fats and their salts in the collections of the Giessen laboratory, they surpassed all in lustre and beauty, and by the well-defined form of the crystals of the soda salt. As above stated, the acid occurs in a free state in the grains, but only in small quantity, the greater part consists of the oily acid ; it probably varies according to the time the grains have been preserved, as is the case with palmitic acid. On the whole the fatty substances may probably constitute 15 per cent, of the grains, of which about a third would consist of the neutral fat. Wittstock obtained 11*2 per cent, of oily matter by pressing the grains between hot plates. A portion of the oily mass was subjected to dry distil- lation, and the products boiled with water, from which on cooling a large quantity of sebacicacid was deposited in beau- tiful needles with a nacrous lustre, and at the same time another fat acid separated on the surface, which was probably margaric acid. This experiment proved the oily fat and oily acid which occur together with that above described in the fruit of Menispermum Cocculus, to be oleine and oleic acid, since, according to Redtenbacher, these alone afford sebacic acid on dry distillation. The colouring matter which is peculiar to the shells could not be obtained in a stale fit for analysis. XXVII. Contributions to the Minute Anatomy of Animals. By George Gulliver, F.R.S., fyc. fyc— No. III*. On the Pus-like Globules of the Blood. TN the Philosophical Magazine for September 1838, (S. 3, -*■ vol. xiii., p. 193) I have described the frequent occurrence of globules of pus in the blood of persons affected with various severe inflammatory and suppurative diseases, and have since shown how the pale globules of the blood of healthy mam- malia and birds differ from the lymph-globules of the same animals (Gerber's Anatomy, p. 83 and 84 ; Appendix to the same, p. 19; and Philosophical Magazine for June, 1842). In the present communication the globules first mentioned will be compared with the pale globules now so well known as belonging to healthy blood. * Communicated by the Author. No. II. will be found in our last Num- ber, p. 107. Minute Anatomy of Animals. — No. III. 169 In some of my earlier observations these two varieties of globules were doubtless confounded ; and their similarity is often so close, that it may well be questioned whether there js any essential difference between them in many cases, al- though it is difficult to avoid attributing to the effects of dis- ease the unusual abundance of pus-like globules in the blood of patients labouring under numerous inflammatory distempers. But it often happens that the pale globules appearing in diseased blood are manifestly different from those found in the blood during health. The former are generally rather larger, more irregular in size and form, and not uncommonly more opake than the latter. The globules occurring in disease too often appear to be tinged, especially when examined by lamp- light, of a red colour, like the blood-corpuscles described by Dr. Barry as in progress of change into pus-globules. Case 1 . — A mare, aged 1 9, was lame of the hind-leg, which in three days became prodigiously swoln ; there were many purulent deposits beneath the integuments, and she had much fever. Some blood, from the facial vein, was now examined, and found to contain an unusual number of pus-like globules, (fig. 1. A.) the average diameter of which was about 2^W*h °f an English inch. They occurred for the most part singly, and occasionally in clumps. When treated with dilute acetic acid the globules exhibited nuclei, generally central but some- times attached to the circumference ; and the smaller particles or molecules (the disc-like objects of Dr. Barry), of which the nuclei were composed were either closely connected together or separated by minutely granular matter (fig. 1 . B.) . On the fifth day, when the disease had increased, some blood from a cutaneous vein of the affected limb contained about half as many pus-like globules as red discs ; the former were most commonly in clusters, and darker-coloured than they were two days before. The pale globules in the blood of a healthy mare, examined at the same time for comparison, were by no means so nu- merous ; they were more regular in size and shape, almost all between yj\,(jth and 2^Votn °f an ,ncn m diameter ; when sub- jected to the action of dilute acetic acid they presented a nucleus', the molecules of which were closely aggregated together; the globules appeared rather paler than those of the diseased blood, and were rarely to be seen in clumps (fig. 1. C). Case 2. — A gelding, aged 8, had the disease termed by veterinarians laminitis, that is to say, inflammation of the vas- cular laminae of the corion beneath the crust of the hoof. The disease was violent; relief was attempted by abstracting blood from the brachial vein, which became inflamed, and the animal soon afterwards died. In the blood there was a 170 Mr. Gulliver on the Minute Anatomy of Animals. vast number of pale globules resembling pus, (fig. 2, A.) be- sides others of a reddish colour. The latter corpuscles (fig. 2, B.) appeared to be composed of very delicate pale enve- lopes including from one to four blood-discs, rarely five or six, some of which were altered in shape, while others pre- sented nearly their usual size and contour. They were not spherical, as some of them appear to be in the figure. The envelopes, which seemed at first like shadows, were distinct enough in different lights, even after the addition of water and dilute acetic acid, and were rendered very obvious by the ac- tion of tincture of iodine. Fig. 1. Fig. 2. Fig. 1. Globules mentioned in case 1. A, pus-like globules of blood from the facial vein ; two of them are round, another is rather oval, a fourth is made up of aggregated granules, and the remaining one is much smaller and more shapeless than the others. B, the same globules treated with dilute acetic acid. C, pale globules from the blood of a healthy mare, in one of which the nucleus is shown by dilute acetic acid. D, blood-discs or unchanged red particles from the same animal for comparison. Fig. 2. Corpuscles described in case 2. A, pus-like glo- bules of blood from the digital vein, as they appeared without addition. B, reddish corpuscles, of which seven are here de- picted, from the same blood ; four of them contain what ap- pear to be single blood-discs, three of which are variously misshapen ; of the three other corpuscles one includes two discs seen on their flat surfaces and touching merely at the mar- gins, another has four slightly overlapping at the edges, and the remaining one incloses a pile of similar discs seen on their edges and with their flat surfaces together. Compare these discs with the unchanged red particles at D in fig. \ . All the objects in both figures are magnified exactly to the same degree, namely, about 800 diameters. Compare the nu- On the Preparation of Quina and Cinchonia. 171 clei at B and C in fig. 1, with those of the lymph and chyle globules, which I have depicted in Gerber's Anatomy. Structure of Fibrine. In the section on this subject in the last Number of the Phi- losophical Magazine, p. 109-111, it should have been stated that in many fibrinous exudations or false membranes, result- ing from inflammation, the structure is the same as that of fibrine, coagulated either after removal from the body or within the circulating channels simply from death. In false membranes the fibrils are often very distinct : they form a de- licate net-work, which incloses exudation corpuscles, much resembling the organic germs before described in pale clots of fibrine formed without inflammatory action. As these fibrils in both instances appear to be formed in the act of coagula- tion, it would require some modification of or departure from the theory of M. Schwann to explain their origin. Tubercle. It has long been a question whether tubercular matter in the lungs be situated in the cellular (filamentous) tissue out- side the air-cells, or at the surface of the mucous membrane within these cells. It may be merely mentioned that I have clearly detected tubercular deposit in the latter situation ; and that Dr. Willis, in his forthcoming English version of Prof. Wagner's Physiology, will give an engraving of tubercular matter within the air-cells. This of course will not decide what is always the case in tubercular consumption ; but it seems to be a fact of interest in regard to the precise seat of tubercle of the lungs. XXVIII. On the Preparation of Quina and Cinchonia. By M. F. C. Calvert, Preparateur du Cours de Chimie appliquee au Jardin des Plantes a Paris. To the Editors of the Philosophical Magazine and Journal. Gentlemen, \ LLOW me, through the medium of your widely-circulated ■**• Journal, to make public a new chemical fact discovered by me relating to the extraction of quina and cinchonia from cinchona bark, by the knowledge of which, I believe, the pro- cess usually followed by the manufacturers of these alkaloids may be considerably improved. In order to obviate some of the difficulties which have hi- therto been experienced in extracting the alkaline bases of cinchonia, it appeared to me desirable to discover a process by which, from a certain quantity of cinchona bark, all the quina and cinchonia contained in it might be extracted. In 172 M . Calvert on the Preparation of Quina and Cinchonia. the French manufactories, and probably also in the English, the same quantity of these bases has never been extracted with any regularity from equal weights of cinchona even of similar quality : this irregularity will, I think, admit of easy explana- tion from the fact which I have ascertained, that quiha is very soluble in lime water and in the solution of chloride of calcium; hence, when lime is employed to precipitate those bases from their solution in the hydrochloric acid, which is used to extract them from cinchona bark, a part of the quina is re-dissolved, especially should the lime be added in excess even in the smallest quantity. It is true that the re-solution of the quina depends in great measure on an excess of lime being added ; but at the same time it must be admitted, that even should the greatest care be taken by the manufacturer to guard against adding an excess of lime, it would be impossible wholly to prevent the solution of some of the quina, as chloride of cal- cium will inevitably be formed, and consequently a part of the quina will be dissolved in it. Considering that such must be the unavoidable result of the process usually followed, and reflecting on the serious, if not insurmountable obstacle which the re-solution offers to the economical manufacture of those important articles, I was led to inquire by experiments whether some other and less objec- tionable means could be discovered of precipitating those sub- stances. I first experimented with solutions of caustic ammonia and potash, and soon found that the use of these alkalies was lia- ble to the same objection as that of the chloride of calcium and hydrate of lime, viz. of dissolving a portion of the qui- na when added in excess. But the result was found to be very different when a solution of caustic soda was employed, as this alkali, even when added in excess, dissolves neither quina nor cinchonia. Of this insolubility I satisfied myself by the following experiment. I precipitated a mixed solution of the sulphates of quina and cinchonia by caustic soda, and afterwards filtered it; the filtered liquor was next divided in two equal parts, one of these treated for the purpose of ascertaining whether any quina had been re-dissolved by the soda ; with this object in view, I saturated the excess of alkali with hydrochloric acid, and then poured chlorine into the neutral solution and afterwards ammonia. It is well known that if there had been a trace of quina or any one of its salts in the solution, a green colour would have been produced*; but in my experi- ment not the slightest colour was observed. * Vide Journal Hcbdomadairc dc Pharmacic (vol. xxii. p. 37). Published by M. Adrien of L}ons. M. Calvert on the Preparation o/Quina and Cinchonia. 173 I repeated this experiment several times both with the sul- phuric and hydrochloric acids, and the result being always similar, I concluded that all the quina had been precipitated and none re-dissolved. To the other portion of the filtered and alkaline liquor, after having saturated it with hydrochloric acid, I applied chloride of lime, which is a very sensible test of the presence ofcinchonia(aswill be made to appear presently), and having obtained no precipitate, I felt satisfied from this experiment that no particle either of quina or cinchonia had been re-dis- solved : I therefore concluded, from the result of these ex- periments, that the process of extracting those two vegeto- alkalies by lime is imperfect, and I propose, instead of em- ploying hydrate of lime for the purpose of precipitating the alkaline bases of cinchonia, that caustic soda should be used, because, by employing it, all the cinchonia, and especially the quina, which may be contained in the acid liquors, will certainly be precipitated ; — an object of great importance to those who are engaged in this branch of manufacture. I afterwards endeavoured to discover a method by which the quantity of cinchonia contained in sulphate of quina might be easily ascertained, as the adulteration of the latter by the addition of the former is a fraud frequently practised in commerce, and one which is with difficulty detected by the chemical means usually applied. For this purpose it has been considered necessary to have recourse to a complicated ana- lysis, especially should it be wished to ascertain the exact extent of the adulteration. As in many works on chemistry it is directed to treat the solution of those salts with an al- kali, by which their bases are precipitated, to wash the pre- cipitate, and then treat it with aether, which dissolves the quina and not the cinchonia, I must here take the liberty of remarking, that should such an analysis be undertaken, it will be necessary to guard against using ammonia or potash, as a small excess of these alkalies will re-dissolve a part of the qui- na ; but, on the contrary, by employing soda this source of error is avoided, no quina being re-dissolved. It is true that the end proposed can be compassed by fol- lowing the directions indicated in many works on chemistry, and using the precautions recommended in the concluding part of the last paragraph. But it appeared to me that it would be advantageous to employ tests by which the fraud in question could be more easily discovered, and I succeeded by the application of the six following reagents, and especially the chloride of lime. I saturated two portions of cold water, one with very pure 174 M. Calvert on the Preparation of Quina and Cinchonia. sulphate of quina, and the other with very pure sulphate of cinchonia; I found that 10 grammes of water contained 0'033 of sulphate of quina, and that the same quantity of water contained 0'165of the sulphate of cinchonia, or five times the proportion of sulphate of quina ; therefore, in order to act on the same quantities of each salt dissolved in the same quantity of water, I took 10 grammes of the solution of sulphate of quina, or 0*033, and only 2 grammes of the saturated solu- tion of sulphate of cinchonia, and to this latter solution I added 8 grammes of water, and thus in both cases I acted on 0*033 of solid salt in 10 grammes of water. 1st. The solution of the sulphate of quina gave a preci- pitate with chloride of lime, which was immediately re-dis- solved by the addition of an excess of the reagent. The solution of the sulphate of cinchonia, on the contrary, gave a precipitate which was not re-dissolved on the addition of even a large excess of the reagent. I afterwards mixed the solutions of the sulphates of quina and cinchonia in equal quantities, and poured into the mix- ture chloride of lime; a precipitate was formed, of which one half was re-dissolved on the reagent being added in excess ; the precipitate which was re-dissolved was quina: hence it appears, that sulphate of quina, mixed with an equal quantity of sulphate of cinchonia, could be separated from it, and the quantity of cinchonia ascertained^ I next experimented on a mixture containing two parts of sulphate of quina and one of sulphate of cinchonia, and a similar result was obtained; that is, a precipitate was produced on the addition of chloride of lime, a portion of which, equal to the proportion of sulphate of quina, was again re-dissolved on the reagent being added in excess. When the small quantity of sulphate of cinchonia upon which I experimented is considered, it will be perceived how easily, by means of these reagents, any adulteration of the sulphate of quina by sulphate of cinchonia may be de- tected, and the smallest quantity of the substance discovered, as quina has no influence on the result of the experiment, provided the liquor is sufficiently diluted to guard against the precipitation of sulphate of lime. In applying the tests the greatest care was taken to pre- vent the precipitation of the sulphate of lime ; and the best proof that can be adduced of this source of error having been avoided was, that if the precipitate had been sulphate of lime, it would not have disappeared in the experiment made with the pure solution of sulphate of quina, and remained in that of the sulphate of cinchonia. M. Calvert on the Preparation of Quina and Cinchonia. 1 75 The following experiment will demonstrate in a manner perhaps still more evident, the non-formation of the sulphate of lime, and will besides show how very sensible a test the chloride of lime is to detect the presence of cinchonia. I took 2 grammes of the solution of sulphate of cinchonia, containing 0*033, and diluted it with 48 grammes of water, and had therefore 33 parts of this substance diffused in 50,000 parts of water ; to this solution I added a little chlo- ride of lime, and obtained a precipitate of cinchonia, whereby the sensibility of the chloride of lime, as a test of cinchonia, as well as the non-precipitation of sulphate of lime, was de- monstrated; for the sulphate of lime formed in the experi- ment must have dissolved in the very dilute solution of cin- chonia which was employed, and consequently the precipitate which appeared could not be attributed to it. The experiment was tried with even double the quantity of water, that is, with 33 parts of sulphate of cinchonia to 100,000 parts of water; but in this case the precipitate was scarcely perceptible. 2nd. The chloride of calcium does not precipitate a sul- phate of quina, but it produces a precipitate with a sulphate of cinchonia. 3rd. The sulphate of quina gives a precipitate with lime- water, but it disappears by an excess of the reagent being added ; while, on the other hand, the sulphate of cinchonia gives a precipitate which remains even on the addition of an excess of the reagent. 4th. The sulphate of quina gives a precipitate with am- monia, which disappears on the addition of it in excess; whereas, in the case of the sulphate of cinchonia, a precipi- tate is produced which does not disappear on adding a large excess of ammonia. 5th. The carbonate of ammonia acts in precisely the same way as ammonia. 6th. With potash, a precipitate is produced with sulphate of quina, but it re-dissolves almost entirely when the potash is added in excess; while with a sulphate of cinchonia it yields a curdy-white precipitate, which is insoluble in an ex- cess of the reagent. 7th. Soda precipitates the bases of both these salts, and the precipitate does not re-dissolve on the addition of an excess ; there is, however, this difference between the precipitate from these two salts; that from the sulphate of quina is pulveru- lent, while that from the sulphate of cinchonia is curdy- white. By means of the first six tests, it will always be easy to di- 176 Dr. Booth on a Theorem in Analytic Geometry. stinguish between quina and cinchonia, and, judging from the results of my experiments, a mixture of those two salts can be detected ; but chloride of lime in particular is the most sensible test of the presence of cinchonia, and it therefore is the reagent which should be employed, when this base is mixed in small proportion with quina or any of its salts. The results obtained by the use of the seven above-mentioned tests fully confirm all that has been said in speaking of the extraction of these alkaloids, and of their quantitative analysis when mixed together. The sulphate of quina treated with the chloride of plati- num gives a white pulverulent precipitate. The sulphate of quina, treated with the same reagent, gives a curdy-white precipitate. The sulphate of quina, treated by the red ferro-cyanide of potassium, gives a precipitate which disappears in an excess of the reagent ; the liquor assumes a greenish-brown colour, and ammonia does not change it nor produce any precipi- tate. The sulphate of cinchonia, submitted to the same reagent, gives a precipitate less deeply coloured than the preceding; it is equally soluble in an excess, but ammonia re-produces the precipitate and destroys the colour in great part. I have likewise performed experiments with the following substances, namely, bichloride of mercury, chloride of nickel and cobalt, the iodide of potassium, and solution of iodine, but they offer no distinctive characters. I will only repeat in conclusion, first, that in the preparation of quina and cinchonia, lime should be replaced by soda: carbonate of potash or soda may be employed, but they have the inconvenience of dissolving part of the cinchonia ; se- condly, that in case of a quantitative analysis being under- taken, the same alkali alone should be employed to precipitate those bodies ; and thirdly, that in case of sulphate of quina being supposed to be adulterated with the sulphate of cincho- nia, and that it may be wished to ascertain the extent of adul- teration, the tests upon which reliance can be placed, are, first, chloride of lime ; secondly, chloride of calcium; thirdly, lime- water; and fourthly, ammonia and carbonate of ammonia. XXIX. On a Theorem in Analytic Geometry. By James Booth, Esq., LL.D., M.R.I.A* IT has been justly remarked by an author who has himself largely contributed to the advance of mathematical science, * Communicated by the Author. Dr. Booth on a Theorem in A?iatytic Geometry. 177 " qu'on sert peut-etre plus encore la science en simplifiant, de la sorte, des theories deja connues, qu'en l'enrichissant de theories nouvelles, et c'est la un sujet auquel on ne saurait s'appliquer avec trop de soin." — Annates de Mathematiques, torn. xix. p. 338. Extending this remark to the simplification of the methods of establishing theorems already known, and remarkable for their difficulty, I am induced to give an exceedingly simple demonstration of a theorem, which may be found at p. 342 of Dupin's Developpements de Geometrie, where the accomplished author bestows more than four quarto pages of analytical cal- culation of extreme complexity on this theorem, and yet leaves its solution incomplete. The following is the theorem to which I allude: — Three points assumed on a right line are always retained in three fixed planes, any fourth point P in this right line will de- scribe an ellipsoid, whose centre is the common intersection of the three fixed planes. Let O x, O y, O z, be the intersections of the three fixed planes, Ox, O y, Oz being the axes of coordinates, and C P the moving right line in any position, meeting the plane of O x y in the assumed point C ; let the distances of P to the points in the planes of x y, y z, z x be c, a,b; and let the an- gles between the axes of x and y,yz, andz x be v, A, jo.; through P let three right lines be drawn P m, Pn, P r, parallel to the lines O x, Oy, O * ; in the line P C assume the point Q, so that P Q = 8, and complete the parallelopiped of which P Q is the diagonal ; let the sides of this parallelopiped parallel to the axes O x, O y, O z be «, |3, y, then we shall have by a well-known theorem, given in most elementary works on the subject*, which expresses the relation between the diagonal sides and contained angles of a paralle- lopiped. a2 + ^ + y2 + 2 /3 y cos A + 2 a y cos p. + 2 a |3 cos v or dividing by 89, 8»! g2 + P . r9 , *lrL-\ , «ay — .. . ««£ + -&+ 2^ cos A + 2-f cosju, + 2-^cosv=l (1.) * See Legendre's Geometry, p. 249 (Brewster's Edition). Phil. Mag. S. 3. Vol. 21. No. 137. Sept. 1842. N 178 Dr. Booth on a Theorem in Analytic Geometry. Now the triangles PCD, P Q r are similar, hence PD:PC::Pr:PQ, orZ:C::y:8, hence z y • im x u y Q — = 4-; in like manner — as -5-, 4- = •£-; c(> a 0 0 0 making these substitutions in (l.)» we find a? y* z* „y z ,xx z „xy i'tJ.\ T + 72 + -5 + 2 / cos A + 2 — Cos p + 2 -i COS V = 1 (2.) or o* cz be ac ab v ' The equation of an ellipsoid whose centre is at the origin when the coordinate planes are rectangular, the equation becomes simply «2 T /)*» + C2 - *' It follows immediately from (2.) that the coordinate planes can never be conjugate planes of the surface, except when rect- angular, as in no other case do the rectangles vanish. To find the coordinates of the point where the tangent plane is parallel to one of the coordinate planes, that of xy. Sup- pose V = 0, being the equation of the surface, the general equation of the tangent plane is dV , ^ d\ . n dV , '"'""■ ^(*-^) + ^Q/-y)+^(z-*') = 0; and when the tangent plane is parallel to that of xy, Now — =• 0 — = 0 dx ~ * dy dV x y z -j— — f- ■— cos v -\ cos a = 0, dx a 0 c dV y x z -r— = 4- -1 cos v -I cos a — 0: dy b a c from these equations, finding the values of x and y in terms of z, and substituting in (2.), there results 2 /" 1 — cos2 A — COS2 jU. — cos2 v -f 2 cos X cos JO. cos v~\ _ 2# L sin2 v J the expression within the brackets is the square of the sine of the angle which the axis of z makes with the plane of xy, calling this angle v J^sinp,K ' sin/>" V ; J When the triangle becomes plane, the sines are changed into the corresponding arcs, and cos a, cos b, cos c are each equal to unity, and we thus derive the known theorem in plane geo- metry, P , P* j i P + p/ + pw — *• N2 [ 180 ] XXX.. Notes on the Effects produced by the Ancient Glaciers of Caernarvonshire, and on the Boulders transported by Floating Ice. By Charles Darwin, Esq., M.A., F.R.S. and F.G.S. #?j_UIDED and taught by the abstract of Dr. Buckland's ^ memoir " On Diluvio- Glacial Phaenomena in Snowdonia and the adjacent parts of North Wales*," I visited several of the localities there noticed, and having familiarized myself with some of the appearances described, I have been enabled to make a few additional observations. Dr. Buckland has stated that a mile east of Lake Ogwyn there occurs a series of mounds, covered with hundreds of large blocks of stone, which approach nearer to the condition of an undisturbed moraine, than any other mounds of detritus noticed by him in North Wales. By ascending these mounds it is indeed easy to imagine that they formed the north-west- ern lateral moraine of a glacier, descending in a north-east line from the Great Glyder mountain. But at the southern end of Lake Idwell the phenomena of moraines are presented, though on a much smaller scale, with perfect distinctness. On entering the wild amphitheatre in which Lake Idwell lies, some small conical, irregular little mounds, which might easily escape attention, may be seen at the further end. The best preserved mounds lie on the west side of the great black per- pendicular face of rock, forming the southern boundary of the lake. They have been intersected in many places by streams, and they are seen to consist of earth and detritus, with great blocks of rock on their summits. They at first appear quite irregularly grouped, but to a person ascending any one of those furthest from the precipice, they are at once seen to fall into three (with traces of a fourth) narrow straight linear ridges. The ridge nearest the precipice runs someway up the mountain, but the outer one is longer and more perfect, and forms a trough with the mountain-side, from 10 to 15 feet deep. On the eastern arid opposite side of the head of the lake, cor- responding but less developed mounds of detritus may be seen running a little way up the mountain. It is, I think, impossi- ble for any one who has read the descriptions of the moraines bordering the existing glaciers in the Alps; to stand on these mounds and for an instant to doubt that they are ancient mo- raines ; nor is it possible to conceive any other cause which could have abruptly thrown up these long narrow steep mounds of unstratified detritus against the mountain-sides. The three * Read before the Geological Society, December 15th, 1841, and the Abstract is published in the Athenaeum, 1842, p. 42. [An Abstract of Dr. Buckland's paper, from the Proceedings of the Society, will appear in an early number of the Philosophical Magazine.— Edit.] Mr. Darwin on the Ancient Glaciers of Caernarvonshire. 181 or four linear ridges evidently mark the principal stages in the retreat of the glacier ; the outer one is the longest, and di- verges most from the great wall of rock at the south end of the lake. The inner lines distinctly define the boundary of the glacier during the last stage of its existence. At this pe- riod a small and distinct glacier descended from a narrow but lofty gorge on the north-western end of the lake ; and here remnants of a terminal moraine may be traced in the little mounds, forming a broken semicircle round a rushy plain, scarcely more than a hundred yards in diameter. The rocks are smoothed, mammillated and scored, all round the lake, and at some little depth beneath the surface of the water, as I could both see and feel. Similar marks occur at great heights on all sides, far above the limits of the moraines just described, and were produced at the time when the ice poured in a vast stream over the rocky barrier bounding the northern end of the amphitheatre of Lake Idwell. I may here mention, that about eighty yards west of the spot where the river escapes from the lake, through a low mound of detritus," probably once a terminal moraine, there is an ex- ample of a boulder broken, as described by Charpentier and Agassiz, into pieces, from falling through a crevice in the ice. The boulder now consists of four great tabular masses, two of which rest on their edges, and two have partly fallen over against a neighbouring boulder. From the distance, though small in itself at which the four pieces are separated from each other, they must have been pitched into their present position with great force ; and as the two upright thin tabular pieces are placed transversely to the gentle slope on which they stand, it is scarcely possible to conceive that they could have been rolled down from the mountain behind them ; one is led, therefore, to conclude that they were dropped nearly vertically from a height into their present places. The rocky and steep barrier over which the ice from the amphitheatre of Lake Idwell flowed into the valley of Nant- Francon, presents from its summit to its very foot (between 400 and 500 feet) the most striking examples of boss or dome- formed rocks; so much so, that they might have served as models for some of the plates in Agassiz's work on Glaciers. When two of the bosses stand near and are separated only by a little gorge, their steep rounded sides are generally distinctly scored with lines, slightly dipping towards the great valley in front. The summit of the bosses is comparatively seldom scored ; but on one close to the bridge over the river Ogwyn, I remarked some singular zigzag scores. At this spot the cleavage of the slate is highly inclined, and owing apparently 182 Mr. Darwin on the Ancient Glaciers of Caernarvonshire, to the different degrees of hardness of the laminae, smooth and gentle furrows have been produced by the grinding of the ice, transversely to the scores, and to the probable course of the glacier. Here, as well as in some few other places, I noticed an appearance which made it vividly clear that these bosses had been formed by some process quite different from ordinary aqueous or atmospheric erosion ; it is the abrupt projection from the smooth surface of a boss of a piece of rock a few yards square, and one or two feet in height, with its surface smoothed and scored like the boss on which it stands, but with its sides jagged : if a statuary were to cut a small figure out of a larger one, the abrupt projecting portions, before he quite completed his work, might be compared to these masses of rock : how it comes that the glacier, in grinding down a boss to a smaller size, should ever leave a small portion apparently untouched, I do not understand. On the summit of some of the bosses on this barrier there are perched boulders : but this phenomenon is seen far more strikingly close to Capel-Curig, where almost every dome of rock south of the Inn is surmounted by one or more large angular masses of foreign rock. The contrast between the rude form of these blocks, and the smooth mammillated domes on which they rest, struck me as one of the most remarkable effects produced by the passage of the glaciers. On the sides of the mountains above Capel-Curig, I observed some bould- ers left sticking on very narrow shelves of rocks, and other boulders of vast size scattered in groups. The largest boulder I noticed there was about 26 feet in length by 12 in breadth, and buried to an unknown thickness. Proceeding down the great straight valley of Nant-Francon, which must formerly have conveyed the united glaciers from Lakes Idwell and Ogwyn, we continue to meet with boss- formed rocks till below the village of Bethesda. From this point towards Bangor these boss-formed rocks become rare ; at least it is certain that a large number of hummocks of rock with rugged surfaces project, whereas higher up in this valley, and in all the great central valleys of Snowdonia, such un- ground hummocks are not to be met with. At Bethesda, un- stratified masses of whitish earth, from ten to forty feet in thickness, full of boulders mostly rounded, but some angular, from one to four feet square, are first met with. This deposit is interesting from the boulders being deeply scored, like the rocks in situ over which a glacier has passed. The scores are sometimes irregular and crooked, but generally quite parallel, as I distinctly saw over the entire side of one large block. Some of the blocks were scored only on one side, others on and on Boulders transported by Floating Ice. 183 two sides, but from the difficulty of turning over the larger ones, I do not know which case is most common. I saw one large block on which the scores on the opposite sides were all parallel ; and another irregularly conical one, four feet in length, of which three-fourths of the circumference was marked with parallel striae, converging towards the apex. In the smaller elongated blocks, from six to twelve inches in diameter, I observed that the striae were generally, if not always, paral- lel to their longer axes, which shows that when subjected to the abrading force, they arranged themselves in lines of least resistance. Out of three large blocks which remained im- bedded in a perpendicular cliff, the vertical sides of two were scored in horizontal lines, and of the third in an oblique di- rection. These several facts, especially the parallel striae on the upper and lower surfaces, show that the boulders were not scored on the spot where they are now imbedded, as seems to have been the case with the boulders described by Mr Mac- laren* in the till near Edinburgh. The contrast is very stri- king in the state of the surface of these boulders, and those which lie scattered high up on the sides of the adjoining hills and of the great central valleys, or are perched on the worn bosses of naked rock ; such boulders, as I particularly noticed, present no signs of scores or strias, as might have been antici- pated, if, as is supposed, they were transported on the surface of the glaciers. In the quarries which I examined, namely, below Bethesda, and at some little height on the eastern side of the village, the till rested on slate-rocks, not worn into bosses. I found, however, a rather smooth pap of greenstone marked with a few deep scores. The till forms, at the height probably of 600 feet above the sea, a little plain, sloping sea- ward ; and between Bethesda and Bangor, there are other gently inclined surfaces composed of till and stratified gravel. Considering these facts, together with the proofs of recent ele- vation of this coast, hereafter to be mentioned, I cannot doubt that this till was accumulated in a sloping sheet beneath the waters of the sea. In composition it resembles some of the beds of till in Tierra del Fuego, which have undoubtedly had this origin. I presume the scored, rounded, and striated boulders were pushed, in the form of a terminal moraine, into the sea, by the great glacier which descended Nant-Francon. Mr. Trimmer f reports, on the authority of some workmen, * Geology of Fife and the Lothians, p. 212. t Proceedings of the Geological Society, vol.i. p. 332, or Phil. Mag. S. 2. vol. x. p. 1 43. Mr. Trimmer was one of the earliest observers of the scores and other marks on the rocks of North Wales. He has also remarked that "some of the larger blocks amid the gravel have deep scratches upon their surface." Mr. Trimmer himself found broken sea-shells in the diluvium at Beaumaris. 184 Mr. Darwin on the Ancient Glaciers of Caernarvonshire, that sea-shells have been found on Moel Faban, two miles N.E. of Bethesda. I ascended this and some neighbouring hills, but could find no trace of any deposit likely to include shells. This hill stands isolated, out of the course of the gla- ciers from the central valleys ; it exceeds 1000 feet in height; its surface is jagged, and presents not the smallest appear- ance of the passage of glaciers : but high up on its flanks (and perhaps on its very summit) there are large, angular and rounded boulders of foreign rocks. Along the sea-coast between Bangor and Caernarvon, and on the Caernarvonshire plain, I did not notice any boss-formed hillocks of rock. The whole country is in most places con- cealed by beds of till and stratified gravel, with scattered boulders on the surface: some of these boulders were scored. From the account given by Mr. Trimmer* of his remarkable discovery of broken fragments of Buccinum, Venus, Natica, and Turbo, beneath twenty feet of sand and gravel, on Moel Tryfan (S.E. of Caernarvon), I ascended this hill. Its height is 1192 feetf above the sea; it is strewed with boulders of fo- reign rock, most of them apparently from the neighbouring mountains ; but near the summit I found the rounded chalk- flints X and small pieces of white granite alluded to by Dr. Buckland. Its form is conical, and it stands isolated: wherever the bare rock protrudes its surface is jagged, and shows no signs of being in any part worn into bosses. The contrast between the superficial part of the bare rock on this hill and on Moel Faban, with that of the rocks within the great central valleys of Caernarvonshire, is very remarkable ; it is a contrast of precisely the same kind as may be observed in these same valleys by ascending on either side above the reach of the ancient glaciers. A little way down the hill, a bed two or three feet in thickness, of broken fragments of slate mixed with a few imperfectly rounded pebbles and boulders of many kinds of rock, is seen in several places to rest on the slate, the upper surface of which, to the depth of several feet, has been disintegrated, shattered and contorted in a very cu- rious manner. The laminated fragments, however, sometimes partially retain their original position. I did not succeed in finding any fragments of shells, but near the summit of the hill on the eastern or inland side, I found beds, at least twenty feet in thickness, of irregularly stratified gravel and boulders, with distinct and quite defined layers of coarse yellow sand, and others of a fine argillaceous • Proceedings of the Geological Society, vol. i. p. 332. [Phil. Mag. loc. cit.] t Murchison's Silurian System, p. 528. j I may mention, that at Little Madely, in Staffordshire, I have found chalk-flints in the gravel-beds, associated with existing species of sea-shells. and on Boulders transported by Floating Ice. 185 nature and reddish colour. These beds closely resemble those of Shropshire and Staffordshire, in which are found (as I have myself observed in very many places) fragments of sea- shells, and which every one, I believe, since the publication of Mr. Murchison's chapters on the drift of these counties, admits are of submarine origin. It may therefore be con- cluded that the layers of coarse and argillaceous sand, and of gravel, with far- transported pebbles and boulders, do not owe their origin to an inundation, but were deposited when the summit of Moel Tryfan stood submerged beneath the surface of the sea. As there are no marks of the passage of glaciers over this mountain (which indeed from its position could hardly have happened), we must suppose that the boulders were transported on floating ice ; and this accords with the remote origin of some of the pebbles, and with the presence of the sea-shells. Within the central valleys of Snowdonia, the boulders appear to belong entirely to the rocks of the country. May we not conjecture that the icebergs, grating over the surface, and being lifted up and down by the tides, shattered and pounded the soft slate-rocks, in the same man- ner as they appear to have contorted the sedimentary beds of the east coast of England (as shown by Mr. Lyell)*, and of Tierra del Fuego ? Although I was unable to find any beds on Moel Faban likely to preserve sea-shells, yet, considering the absence of the marks of the passage of glaciers over it, I cannot doubt that the boulders on its surface were transported on floating ice. The drifting to and fro, and grounding of numerous icebergs during long periods near successive uprising coast-lines, the bottom being thus often stirred up and fragments of rock dropped on it, will account for the sloping plain of unstratified till, occasionally associated with beds of sand and gravel, which fringes to the west and north the great Caernarvonshire mountains. In a paper read before the Geological Society f, I have re- marked that blocks of rock are transported by floating ice un- der different conditions; 1st, by the freezing of the sea, in countries where the climate does not favour the low descent of glaciers ; 2nd, by the formation of icebergs by the descent of glaciers into the sea, from mountains not very lofty, in la- titudes (for instance in that of Geneva, or of the mouth of the Loire, in the southern hemisphere) where the surface of the * " On the Boulder Formation of Eastern Norfolk ;" Phil. Mag., S. 3, vol. xvi. May 1840, p. 351. t May 5th. 1841, " On the distribution of the Erratic Boulders, and on the contemporaneous unstratified deposits of South America.'' [Phil. Mag. S. 3, vol. xix. p. 536.] 186 Mr. Darwin on the Ancient Glaciers of Caernarvonshire, sea never freezes ; and 3rd, by these two agencies united. I have further remarked that the condition and kind of the stones transported, would generally be influenced by the manner of production of the floating ice. In accordance with these views, I may remark that it does not seem probable from the low level of the Chalk-formation in Great Britain, that rounded chalk-flints could often have fallen on the surface of glaciers, even in the coldest times. I infer therefore that such pebbles were probably inclosed by the freezing of the water on the ancient sea-coasts. We have, however, the clearest proofs of the existence of glaciers in this country ; and it appears, that when the land stood at a lower level, some of the glaciers, as in Nant-Francon, reached the sea, where icebergs charged with fragments would occasionally be formed. By this means we may suppose that the great angular blocks of Welch rocks, scattered over the central counties of England, were trans- ported*. I looked carefully in the valleys near Capel-Curig and in Nant-Francon for beds of pebbles, or other marks of marine erosion, but could not discover any : when, however, Moel Tryfan and Faban stood beneath the level of the sea, inland creeks of salt-water must have stretched far up or quite through these valleys, and where they were deep, the glaciers (as at present in Spitzbergenf) would have extended, floating on the surface of the water, ready to become detached in large portions. From the presence of boss-formed rocks low down in the valley of Nant-Francon, and on the shores of the Lakes * On the summit of Ashley Heath in Staffordshire, there is an angular block of syenitic greenstone, four feet and a half by four feet square, and two feet in thickness. This point is 803 feet above the level of the sea. From this fact, together with those relating to Moel Tryfan and Faban, we must, I think, conclude that the whole of this part of England was, at the period of the floating ice, deeply submerged. From the reasons given in my paper (Phil. Trans., 1839 [Phil. Mag. S. 3, vol. xiv. p. 363.]), I do not doubt that at this same period the central parts of Scotland stood at least 1300 feet beneath the present level, and that its emergence has since been very slow. The boulder on Ashley Heath probably has been exposed to at- mospheric disintegration for a longer period than any other in this part of England. I was therefore interested in comparing the state of its lower surface, which was buried two feet deep in compact ferruginous sand (con- taining only quartz pebbles from the subjacent new red sandstone), with the upper part. I could not, however, perceive the smallest difference in the preservation of the sharp outlines of its sides. I had a hole dug under another large boulder of dark green felspathic slaty rock, lying at a lower level; it was separated by 18 inches of sand, (containing two pebbles of granite, and some angular and rounded masses of new red sandstone) from the surface of the new red sandstone. One of the rounded balls of this latter stone had been split into two, and deeply scored, evidently by the stranding of the boulder. t Dr. Martens on the Glaciers of Spitzbergen, New Edinb. Phil. Journ. 1841, (vol. xxx.) p. 288. find on Boulders transported by Floating Ice. 187 of Llanberis (310 feet above the sea), it is evident that gla- ciers filled the valleys after the land had risen to nearly its present height ; and these glaciers must have swept the valleys clean of all the rubbish left by the sea. As far as my very limited observations serve, I suspect that boss or dome-formed rocks will serve as one of the best criterions between the ef- fects produced by the passage of glaciers and of icebergs*. Dr. Buckland has described in detail the marks of the pass- age of glaciers along nearly the whole course of the great central Welch valleys ; I observed that these marks were evi- dent at the height of some hundred feet on the mountain-sides, above the water-sheds, where the streams flowing into the sea at Conway, Bangor, Caernarvon, and Tremadoc, divide : hence it appears that a person starting from any one of these four places (or from some way up the valley where the gla- cier ended), might formerly, without getting off the ice, have come out at either of the other three places, or low down in the valleys in which they stand. The mountains at this pe- riod must have formed islands, separated from each other by rivers of ice, and surrounded by the sea. The thickness of the ice in several of the valleys has been great. In the vale of Llanberis I ascended a very steep mountain, E.N.E. of the upper end of the upper lake, which slightly projects where the valley bends a little. For the lower 1000 feet (estimated, I think, correctly) the marks left by the glacier are very distinct, especially near the upper limit, where there are boulders perched on bosses of rock, and where the scores on the nearly vertical faces of rock are, I think, more distinct than any others which I saw. These scores are generally slightly in- clined, but at various angles, seaward, as the surface of the glacier must formerly have been. But on one particular face of rock, inclined at an angle of somewhere about fifty degrees, continuous, well-marked and nearly parallel lines sloped up- wards (in a contrary sense to the surface of the glacier) at an angle of 18° with the horizon. This face of rock did not lie parallel to the sides of the main valley, but formed one side of the sloping end of the mountain, over and round which the ice appears to have swept with prodigious force, expanding laterally after being closely confined by the shoulder above * In the Appendix to my Journal of Researches (1839), I endeavoured to show that many of the appearances attributed to debacles, and to the movements of glaciers on solid land, would in all probability be produced by the action of stranded icebergs. I have stated (p. 619), on the author- ity of Dr. Richardson, that the rocky beds of the rivers in North America which convey ice, are smoothed and polished; and that (p. 620) the ice- bergs on the Arctic shore drive before them every pebble, and leave the sub- marine ledges of rock absolutely bare. 188 Mr. Josiah Rees's Application of the Formula mentioned. At this point, where the glacier has swept to the westward, and has expanded, its surface seems in a short space to have declined much : for on a hill lying about a quarter of a mile N. W. of the shoulder, and forming a lower part of the same range (it stands S.S.E. of the Victoria Inn, and has a reddish summit), the marks of the passage of the glacier are at a considerably lower level. At the very summit, however, of this hill, several large blocks of rock have been moved from their places, as if the ice had occasionally passed over the summit, but not for periods long enough to have worn it smooth. I cannot imagine a more instructive and interesting lesson for any one who wishes (as I did) to learn the effects produced by the passage of glaciers, than to ascend a mountain like one of those south of the upper lake of Llanberis, constituted of the same kind of rock and similarly stratified, from top to bottom. The lower portions consist entirely of convex domes or bosses of naked rock, generally smoothed, but with their steep faces often deeply scored in nearly horizontal lines, and with their summits occasionally crowned by perched boulders of foreign rock. The upper portions, on the other hand, are less naked, and the jagged ends of the slaty rocks project through the turf in irregular hummocks ; no smooth bosses, no scored surfaces, no boulders are to be seen, and this change is effected by an ascent of only a few yards ! So great is the contrast, that any one viewing these mountains from a distance, would in many cases naturally conclude that their bases and their summits were composed of quite different formations. XXXI. Application to particular instances of the general Formula for eliminating the Weights of Mixed Bases. By Josiah Rees, Jun., F.G.S., of Her Majesty's Ordnance Geological Survey *. HPHE general formula for eliminating the weights of any two •*■ bases, where the whole weight of any particular acid with which they are combined has been previously ascertained, is not easily available to those who are unaccustomed to mathe- matical inquiry. If, however, we apply the general rule to particular in- stances, we are enabled to obtain a very simple place for each, by the application of which the weight of the bases may be ascertained. I have thought it would not be altogether useless to draw up a few such rules for the use of chemists. * Communicated by the Author. for eliminating the Weights of Mixed Bases. 189 The following combinations have been chosen as the most likely to come under the notice of the practical chemist: — Potash and soda combined with sulphuric acid ; sodium and magnesium with chlorine ; sodium and calcium with chlorine ; lime and magnesia with carbonic acid. The equivalents adopted by Brande have been used in the calculation. Carbonic acid ... 22 Magnesium 12 Chlorine 36 Potash 48 Sulphuric acid ... 40 Soda 32 Calcium 20 Potassium 40 Lime 28 Sodium 24 1 . When potash and soda exist in combination with sul- phuric acid, the weight of mixed sulphates being known, and also the weight of acid with which they are combined, to as- certain the weight of each base present. Rule. — Multiply the whole weight of material experimented on by 15; from the product subtract 27 times the weight of the acid in combination, and divide the remainder by 5, the quotient will be the weight of potash : b being the weight of material experimented on, and a the known weight of acid, the rule stands thus : — 15 b — 27 a ., . ,. c l n == the weight of potash. The whole weight of acid and the weight of potash being as- certained, the weight of soda is of course at once known by subtracting the weight of acid and potash from that of the whole material experimented on. 2. When magnesium and sodium exist in combination with chlorine, the whole weight of the chlorine in combination be- ing known, to ascertain the weight of each base. Rule. — Multiply the whole weight of material experimented on by 6, from the product subtract 8 times the weight of the chlorine, and divide the remainder by 3, the quotient will be the weight of the sodium : — = weight of the sodium. 3 h 3. When sodium and calcium exist in combination with chlorine, the weight of chlorine being known, to ascertain that of each base. Rule. — Multiply the whole weight of material experimented on by 18; from the product subtract 28 times the weight of chlorine, and divide the remainder by 3 ; the quotient will be the weight of the sodium : — 18 6 — 28 a . i ; f i- = weight of sodium. 190 Mr. Davies on the Employment of Polar Coordinates 4. When lime and magnesia exist in combination with car- bonic acid, the whole weight of the acid in combination being previously known, to ascertain the weight of each base. Rule. — Multiply the whole weight of material experimented on by 77 ; from the product subtract 147 times the weight of acid, divide the remainder by 22, and the quotient will be the weight of lime : — 77 £ — 147 a -v. r.,1 r — = weight or the lime. 22 & Crickhowel, July % 1842. XXXII. On theEmployment of Polar Coordinates in expressing the Equation of the Straight Line, and its application to the proof of a property of the Parabola. By T. S. Davies, Esq., F.R.S., F.S.A., fyc, Royal Military Academy, Wool- wich *. A BOUT ten years ago I gave in a note to my paper on **■ Spherical Coordinates (in the Trans. Roy. Soc. Edinb., vol. xii.) the general equation of a straight line in reference to polar coordinates. The idea, which is very simple, was suggested by the method which I had employed in the dis- cussion of spherical loci ; the equation of the line in piano corresponding to that of the great circle on the surface of the sphere: and it was made apparent that the treatment of the straight line by such means was quite as simple and elementary in all its details as that by means of rectilinear co- ordinates. Beyond the occasional employment of the expression d r • ,.'-to express the angle of the tangent and radius vector, or the relation between the perpendicular on the tangent and the corresponding radius vector, the method of polar coor- dinates has been generally disregarded by mathematicians in treating of the tangents and normals to curve lines : and I do not recollect a single instance where the general polar form of the equation of a line subject to its adequate number of defining conditions has even been noticed, much less used, by any author, prior to the appearance of my paper. However, that it is a very efficient method of investigating the properties of rectilineal figures, any reader may readily convince him- self by a few experiments upon such theorems as express those properties ; and I wish here to illustrate its utility in reference to tangencies by the investigation of a theorem which has ex- * Communicated by the Author. in expressing the Equation of the Straight Line. 191 cited some interest amongst the readers of the Philosophical Magazine, and which treated purely by rectangular coordinates, involves expressions of considerable complexity. Theorem. If three tangents to a parabola mutually inter- sect, the circle described about the triangle formed by them will always pass through the focus of the parabola*. The polar equation to the tangent at the point rl0l of any curve is r {cos (0-00 - sin (0-0,) ^J-| = rx. Edinb. Trans., vol. xii. p. 408. And the equation of the parabola, referred to its focus as pole and diameter as origin of polar angles, is, at the point rx Ql9 ^(1+008 0!) = 2 a. From (2.) we get drx sin0t d x ~ 1+COS0J ' which, inserted in the general equation, gives at once r {cos (0— 0j) + cos (0-00 COS0J— sin (0— 0j) sh^} = rx (1+cos0j), or finally, r cos (0—1 0 x) cos i 0! = a (1 .) Similarly, r cos (0— A02) cos 1 02 = «, (2.) and r cos (0— i03) cos|03 = a, (3.) which represent the three tangents at t\ 01} r^ 02, r3 03 ; and from which the proof of the theorem is deducible as follows: Denote by Rj 6X the coordinates of the intersection the tangents represented (2, 3), by R282 that of (3, 1), and by R3 e3 that of (1, 2). Then we get immediately *i = i(02+03) Rj = a sec A 02 sec A 03 ®i-»2=i (*2-*i) e2 = -§(03+0i) R2 = a sec A 03 sec ^ 0t %-%=h %-**> ®3 = 2^1+02) R3 = a sec \ 01 sec J 02 e3—ei=2 (^1 — ^3) Hence, * Wallace, in the Mathem. Repos., vol. ii. p. 54, Old Series, and in his Conic Sections, p. 167 ; Tirnmermanns.inQuetelet's Correspondance Math, et Phys., torn. ii. p. 75; Strong and Avery, Gill's Math. Misc. New York, No. 6; Jones in the Gentleman's Diary, 1831; Poncelet, Traite des pro- prietes projectives, section iv. Annates des Mathcmatiques, tom. viii.; Phil. Mag., S. 3, vol. ix. p. 100; x. pp. 32, 35; xi. p. 302; and Young's Conic Sections, p. 189. I would not be understood to contest the simplicity of the geometrical methods of proving this theorem ; but merely take this theorem as an il- lustration of the occasional advantage of the polar over the rectangular equation of the tangent to a curve. 192 Mr. Warrington on the Change of Rj sin (82 — e3) = a (tan J 03— tan 1 02) R2 sin (63— et) = a (tan A 5,- tan J 03) R3sin {e1 — 62) = a (tan ^ 02- tan £0,). By addition of these, we have RT sin (62— e3) + R2 sin(e3-Oj) + R3 sin (©i — ©a) = °» which is the criterion of the circle through Rj 8j , R2 62, R3 63 passing through the polar origin, or, in this case, the focus of the parabola. It may not be irrelevant to remark, that the geometrical property expressed by the values of e„ 62, 63 in terms of 0„ #2, 09 is the familiar one found in all works on the conic sections ; as in Hutton's Course, for instance, at vol.ii. pp. 1 1 1, 135, 147 of the 11th edition, and nearly in the same places in the edition now printing. Lines drawn to the focus of a conic section from the intersec- tion of two tangents, bisects the angle formed by the radii vector es drawn to the points of contact. The property in reference to the other conic sections is deducible in the same way, as will be obvious on forming the equations Of the tangent in each of them, and which are put down here for the ellipse and hyperbola : — r {cos (0-0J0 + e cos } = a (1-e2), and r {cos (0— 0,)0— e cos } = a (e2— 1). Many other properties may be obtained by this method with great simplicity and elegance; but the method being once pointed out, the details are too elementary to require further notice in this place. Royal Military Academy, July 5, 1842. XXXIII. On the Change of Colour in the Biniodide of Mer- cury. By Robert Warington, Esq., Secretary to the Chemical Society *. TT is well known that when a solution of the iodide of po- ■*■ tassium is added to a solution of the bichloride or perni- trate of mercury, a yellow precipitate, passing rapidly to a scarlet, is formed ; this is the biniodide of mercury. It is soluble in an excess of either of the agents employed for its production, and if this act of solution be assisted by heat, the biniodide may be obtained, as the solution cools in fine scarlet crystals, having the form of the octohedron with the square base, or its modifications. * Communicated by the Chemical Society, having been read Feb. 1, 1842. Some of the facts related in this paper had been previously ob- served by Mr. Talbot, and described by him in Phil. Mag. Third Series, vol. ix. p. 2. — Edit. Colour in the Biniodide of Mercury. 193 If this precipitated biniodide, in the dry state, be subjected to the action of heat, it becomes of a bright pale yellow colour, fuses into a deep amber-coloured fluid, and gives off a vapour which condenses in the form of rhombic plates of the same bright yellow;- these crystals, by any mechanical disturbance, arising from the unequal contraction of their molecules in cool- ing, from varying thickness in different parts of the same cry- stal, or from partial disintegration, return again to the origi- nal scarlet colour of the precipitate, the change commencing, in the latter case, from the point ruptured, and spreading over the whole of the crystalline mass; they may however be fre- quently preserved in the yellow state for a great length of time, if sublimed slowly and not exposed to the contact of other sub- stances, which is readily effected by conducting the sublima- tion in closed vessels, and allowing the crystals to remain in them undisturbed. The resumption of the scarlet colour has been attributed to an alteration in the molecular arrangement of the crystals, and it was with the view of clearly ascertaining this point that the following microscopic investigations were undertaken. When a quantity of the precipitated biniodide is sublimed, the resulting crystals are very complicated in their structure, consisting of a number of rhombic plates, of varying size, su- perposed, sometimes overlapping each other and causing con- siderable variableness in their thickness, but generally leaving the extreme angle and the two lateral edges clear and well- defined ; the annexed sketch, taken by the camera lucida from the field of view of the microscope, will give a better idea of their character. The length of these crystals was about *01 5 of an inch in length. On cooling, the first change that is ob- served is usually a scarlet marking, commencing at the ex- treme angle and extending gradually inwards, always retain- ing a perfectly well-defined line in its progress; when this change has reached as far as the line ab, fig. 1, the scarlet line will suddenly shoot along one of the lateral edges, as shown at c d, and instantly the whole mass is converted, in a most rapid and confused manner, which the eye in vain endeavours to fol- low, to the scarlet colour, the crystal being frequently, if de- tached, twisted and contorted during the transition. In order to obtain these crystals in a more defined and clearly developed form, a small glass cell was constructed of two slips of window-glass, leaving a space of about the thickness of cartridge paper between the upper and under plates, in which the sublimations could be readily conducted, and the whole of the subsequent changes at once submitted to the microscope ; Phil. Mag. S. 3. Vol. 21. No. 137. Sept. 18*2. O 194< Mr. Warington on the Change of by this means beautifully well-defined and perfect crystals Fig. 1. were obtained, having the form of right rhombic prisms, as in Fig. 2. the accompanying outlines, fig. 2, a and b. The follow- ing interesting phagnomena were then observed : a de- fined scarlet line of varying breadth would shoot across the crystal, as at 1 . c, d, e,f, fig. 2, and then gradually spreadthroughoutthewhole of its structure, keeping a straight and well-defined line in its onward progress, until the whole had undergone the change of colour. Nos. 2, 3, 4f, 5 in e, and No. 2 in f, are the stages which the transition had reached at intervals of observation; in many cases, after the crystal has undergone this metamorphosis, two angles can be distinctly seen, as at e, fig. 1, and at times two edges are visible, as at c 6 and d 6, fig. 2. This observation must of course de- pend entirely on the position of the crystal to the eye of the observer. These phaenomena prove, I consider, in the most perfect manner, that the change in the colour of this compound arises •©" V D Colour in the Biniodide of Mercury. 195 from the plates of the crystal having been separated from each other, by the means alluded to, in the direction of their clea- vages ; and in further confirmation of this view, the lamina? so separated may, by the sudden application of heat, be again fused together, and the yellow colour reproduced without ma- terially altering the dimensions of the crystal, a slight round- ing of the edges from partial sublimation being the only other concomitant. When the temperature is raised slowly and the sublimation conducted with great care, a verylarge proportion of red cry- stals, having a totally different form, are obtained, the octahe- dron with the square base, YW. 3. as shown fig. 3, a, b, c, d, e. If, however, the heat is quickly raised, the whole mass of the sublimed cry- stals are yellow and of the rhombic form. It is evident from these facts, that the biniodide of mercury has two vapours which are given off at different temperatures, and also that it is dimorphous, which facts have been sub- stantiated by some experiments of M. Frankenheim, who has carefully examined this part of the subject. From the circumstance that the first effect which occurs in the process for preparing this iodide by precipitation is the pro- duction of a yellow powder which passes rapidly through the orange colour to a scarlet, I was induced to submit this phe- nomenon also to the test of microscopic examination, and with this valuable instrument of research, results were exhibited which could not have been anticipated. As I expected, the precipitate was in small crystalline grains, and the first step of the investigation was to effect its formation in the field of view of the microscope, so as to observe, directly as they occurred, the transitions of colour which have been alluded to, and this was effected by the following means : — A slip of common win- dow-glass, about three inches long by one and a half wide, and having a very narrow slip attached on one of its edges, so as to act as a ledge, was taken, and a drop of the salt of mercury employed placed on it ; this was then covered with a small piece of extremely thin glass, about one inch long by half an inch wide, and the whole carefully adjusted to focus in the field of the instrument; the iodide of potassium was then in- troduced by capillary attraction between the glasses. The instant the solutions came in contact, a myriad of pale-yellow crystals, having the same rhombic form as those obtained by 02 196 Mr.Warington on Change of Colour in Biniodide of 'Mercury. sublimation, formed in a curved line across the field of view and extended slowly downwards ; by the strong transmitted light these minute crystals appeared colourless ; but when viewed by reflected light, the pale yellow colour was readily apparent. After a short interval a very extraordinary change commenced; the crystals, which had been perfectly sharp and well-defined, became ragged at their edges, as though some dissolving action were going on, gradually decreased in size, and at last disappeared altogether; but as this act of solution progressed, numbers of red crystals made their appearance, forming across the field and following at a regular distance the yellow crystals as they disappeared, and occupying their place. These red crystals, which appear to be formed by the disintegration through the medium of solution, if I may be allowed the expression, from those first produced, had the form of the octohedron with the square base, exactly similar to those procured by careful sublimation at a low heat, only modified in the most beautiful manner. Some few of these are sketched in the forms, «,&,c, d, e,f, g, //, fig. 4. When either the salt of mercury or the iodide of potassium, employed in the production of the biniodide of ( mercury, was in excess, another curious act of disintegration took place ; the red crystals in fig. 4- were slowly dissolved, aproperty mentioned in the first part of this ft, paper, the first act of solution y i \ commencing apparently by the k f^l k _J disjunction of the crystals «, b, c, f g, h, at the lines of marking, these lines being at first bright red, and gradually deepening in colour when the act of solution commenced, and at last perfect separation taking place, so that the light could be seen between the compartments. At times the field would become dry from evaporation, and some of the yellow rhombic crystals which had not been dissolved, prior to the formation of the octohe- dra with the square base, were observed with scarlet lines on them similar to the first act of transition in the sublimed cry- stals, as shown at g 1 and 2 in fig. 2. By polarized light the appearances now described were beautiful beyond all description, the yellow crystals present- ing the most superb and brilliant colours, varying in hue with the varied thickness of the crystalline plate, and in the dark field having the appearance of the most splendid gems the Mr. Croft on a new Oxalate of Chromium and Potash. 197 imagination can conceive : the red crystals do not appear to be affected by polarized light, so far as the display of colour is concerned. The magnifying powers used in these investigations were, for the experiments on the sublimed crystals, 200 times linear measurement or diameters; in the precipitated compound, 620 diameters. XXXIV. On a new Oxalate of Chromium and Potash. By Henry Croft, Esq.* IT is well known that in 1830 Wilton Turner accidentally discovered a salt composed of oxalate of the oxide of chro- mium and oxalate of potash. Its curious optical properties have been examined by Brewsterf. Gregory also discovered the same salt independently, and proposed a much better me- thod for obtaining it than that used by Turner, which con- sisted in adding oxalic acid to a solution of bichromate of po- tash until effervescence ceased : the solution became deep green or black, and on evaporation yielded beautiful crystals of the black salt. Gregory supposed it to consist of 3 equi- valents of oxalic acid, 2 of potash, 1 of oxide of chromium, and 6 of water. Its true composition, 3 (KO, C2 Oa) 4- Cr2 Oa, 3 C2 03 + 6 HO has been shown by Graham and Mitscher- lich, who have also prepared a number of salts similarly con- stituted. On attempting to prepare the black salt by Turner's method I could never completely succeed, but obtained in its stead, when a very concentrated hot solution of the bichromate was employed, a red granular precipitate, which proved to be a new salt, and forms the subject of the present notice. Perhaps the best method of preparing it is that above de- scribed, viz. to employ as concentrated a solution of the bichro- mate as possible, in which case the salt crystallizes out on cooling. The precipitated salt must be redissolved in a small quantity of water and allowed to crystallize. It is however one of the most difficult salts to crystallize that is known : in nine cases out of ten it separates in the form of a somewhat granular bluish gray powder, and it appears to be only under particular circumstances that it will crystallize well, which, however, I was not able to discover. It does not seem to * Communicated by the Chemical Society, having been read February 15, 1842. [t See Phil. Mag. Third Series, vol. vii. p. 436. Some of the optical and crystallographical properties of this salt have also been described by Mr. Talbot, in Phil. Mag. Third Series, vol. x. p. 218, and vol. xiv. p. 21.— Edit.] 198 Mr. Croft on a new Oxalate of Chromium and Potash, crystallize any better by spontaneous evaporation than out of a very concentrated solution; it seems however to form more regularly in warm air, as in summer. The best crystals are generally formed on the surface of the solutions : they are very minute, in the form of triangular plates ; when the crystals form a mass at the bottom of the liquid the plates are thicker, but their form is indistinguishable. The salt is of a deep red colour by reflected as well as by transmitted light; the solu- tion is green, or even black (when concentrated) by reflected and red by transmitted light. The solution when at a boiling temperature remains red, as is seen best by candle- light : the same is the case with the solution of the black salt, which shows that the purple oxide of chromium contained in these salts is not converted by a boiling heat into its green modification; the purple oxide must, however, as is well known, be first brought into combination with the oxalic acid, for the black salt can never be obtained by dissolving green oxide of chromium in binoxalate of potash. A solution of caustic potash added to a solution of the red salt turns it bright green, but causes no precipitate until boiled, when the greater part of the oxide of chromium is thrown down. Carbonates of the alkalies partly change the colour in the same manner, but do not precipitate the oxide so readily. Ammonia causes no precipitate, nor does chloride of calcium, owing to the formation of Dingler's oxalate of chromium and lime; when ammonia is added a green precipitate containing oxide of chromium is formed. This salt contains a large quantity of water of crystalliza- tion, which can only be driven out by a strong heat, as is also the case with the black salt (Graham). It loses about 15-16 per cent, at 100° cent., and 19 per cent, at 200° cent. The last portions of water can only be driven out at 300° cent. Near this point the salt begins to be decomposed, and conse- quently the determination of the water is rendered somewhat difficult. per cent. 0-9986 gramme of salt lost 0*2638 water = 26*42 0-7481 0*1965 ... = 26'27 0-8971 0-2532 ... = 28'22 The determinations of the oxide of chromium and the po- tash were performed in the following manner. The salt was heated red-hot : in this operation great care must be taken, for the salt possesses the curious property of decomposing with considerable violence (without explosion) into a green powder, which unless the heat is applied very gradually, is forced out of the crucible, and the analysis is thus lost. When the temperature is raised gradually the crystals retain their Mr. Croft on a new Oxalate of Chromium and Potash. 199 form, but become of a bright dark green colour : as soon as the decomposition of the oxalates commences they fall into a light green powder, which when stronger heated becomes brown. In closed vessels carbonate of potash is formed; in open ones, when the heat is continued for a length of time, cnromate is produced. This chromate must be extracted by water, reduced, and the oxide of chromium precipitated by ammonia : in this operation, however, it is better to evaporate the ammoniacai solution to dryness, as the ammonia always dissolves a small quantity of the oxide. This method is pre- ferable to that usually employed (Heinrich Rose's Analytical Chemistry) : the ammoniacai and potash salts must be dis- solved out, evaporated, the ammonia driven off, and the potash determined either as chloride or by means of platinum. The oxalic acid may be determined by boiling the salt with sulphuric acid, as proposed by Prof. Graham. The salt being excessively difficult to crystallize, it seldom happens that a perfectly homogeneous substance can be ob- tained for analysis : the method of analysis is moreover some- what complicated, and consequently the analyses do not agree so perfectly as could be desired. i. a. in. iv. v. vi. Cr2Os 21*80 21-83 23*11 22'05 21-10 24*11 KO 13-18 13-11 12-22 12-92 C2Oa 37*00 36-98 40-89 The water as obtained by other experiments, is H O 26*42 26-27 28*22 The most plausible formula is KO, C2 03 + Cr2 09 3 C2 Oa -1- 12 HO. C203 4 1811*50 38*098 Cr2Os 1 1003-63 21*107 KO 1 589*92 12*405 HO 12 1349*75 28*390 4754-80 100*000 This differs from the black salt in containing one atom of basic oxalate instead of three. It may be said to be related to the black salt in the same way as metaphosphates are to phosphates. It is evident, therefore, that if we add two atoms of oxalate of potash to one atom of the red salt, we ought to obtain the black salt, which is indeed the case. 2*37 grammes of red salt were mixed with 1*15 gr. of oxalate of potash (these are the atomic proportions), the solution boiled and evaporated, they yielded 3*119 grs. of the black salt in good crystals, and perfectly pure : according to theory it ought to have given 3*070. The weight of the black salt must be equal to that of the red salt, plus two atoms of anhy- 200 Mr. Croft on a neta Oxalate of Chromium and Potash. drous oxalate of potash, minus six atoms of water. The agreement of the experiment with the calculation speaks for the correctness of the above formula, in which one might, perhaps, otherwise not place so much confidence. The constitution of this salt led me to consider the theory of its formation, and also that of the black salt, more particu- larly as in employing the known formula} for making the black salt I always obtained it mixed with other bodies. In forming the red salt from bichromate of potassa, 7 atoms of oxalic acid are required. K O, 2 Cr 03 and 7 C2 Os = K O, C2 03 + Cr2 03, 3 C2 Osand 3 C2 03 + 3 O, or 6 C 02. On mixing the two substances in this proportion I obtained perfectly pure red salt. It is evident that seven atoms of ox- alic acid, either free or in combination with potash, must be used in making the black salt. None of the numbers in the formulae given for preparing the black salt agree with this. Dr. Gregory gives 190 parts bichromate of potash, 157'5 parts crystallized oxalic acid, and 517 parts binoxalate of pot- ash ; that is, one atom of the bichromate, two atoms oxalic acid, and three of binoxalate of potash; on trying these num- bers I obtained a mixture of black salt with oxalate and chro- mate of potash. Prof. Graham proposes one part of bichromate, two of bi- noxalate, and two of crystallized oxalic acid. In these pro- portions a large quantity of chromate of potassa remains un- decomposed, which requires, if 19 grains bichromate, 23 grains binoxalate, and 16 grains crystallized oxalic acid be taken, exactly 36 grains of crystallized oxalic acid to effect its perfect decomposition, and making the whole quantity of oxalic acid 52 grains. According to the formula which I would propose, there are required 19 grains bichromate of potash 23 ... oxalate of potash 55 ... crystallized oxalic acid. If the salts be taken in these proportions, nothing but black salt is obtained ; it is however better to evaporate the whole to dryness and then re-dissolve. I have not been able to obtain an intermediate salt, namely, 2 K O, C2 03 4- Cr2 03, 3 C2 03. This, if it exists, ought to be produced from two atoms chromate of potash, and eight atoms oxalic acid : I obtained, however, oxalate of potash and red salt. A similar salt may probably exist with oxide of iron, but it does not crystallize. On dissolving sesquioxide of iron in quadroxalate of potash a solution is obtained, which dries to a brown gummy mass without traces of crystallization. [ 201 ] XXXV. Some additional Observations on the Red Oxalate of Chromium and Potash. By Robert Warington, Esq., Secretary to the Chemical Society*. tTAVING in the year 1832 obtained this salt by the same -■■•*■ method as that described by Mr. Croft, namely, in the endeavour to prepare the dark blue oxalate of chromium and potash by the process originally given by its discoverer Dr. Wilton Turner, and having in my possession some crystals of a much larger size than those usually obtained, I was induced to avail myself of the kind offer of Professor Miller of Cam- bridge, " to determine the form of any crystalline products that the members of the Society might obtain in their re- searches," and have great pleasure in laying before the So- ciety the following letter and measurements : — " St. John's College, Cambridge, April 25,1842. " Dear Sir. — The crystals of the oxalate of chromium and potash are represented in the accompanying figure. The numbers expressing the angles between normals to the faces must be considered as rough approximations only, for although I measured all the measurable crystals you sent me, the variations of the angles between corre- sponding faces showed that the crystals were by no means so perfect as could be wished. " The angles given are however abundantly accurate for the pur- pose of identifying the substance. One of the crystals was a twin, the face (a) being the twin face or the face with respect to which the two individuals were symmetrically situated. " Oxalate of Chromium and Potash. System Oblique prismatic. '*■ Angles between normals to the faces of the crystal. ac 70° 45' cp 50° 40' ah 33 2 cm 77 32 ch 37 43 a r 61 0 bp 53 13 «/78 30 ck 59 16 a'q 63 50 ap 47 49 bfZl 40 am 49 5 " The faces ap rf q are all in one zone ; h p b are in one zone ; k q b are in one zone ; a he k are in one zone. The other zones are sufficiently well indicated by the parallelisms of the edges. " The symbols of the faces are, — a (100), b (010), c (001), h (101) p (111), q (111),/(011), m (110), k (101), r (112). " I remain yours faithfully, " W. H. Miller." * Communicated by the Chemical Society, havinsr been read Mav 17 1842. J ' 202 Prof. Kelland's Reply to some Objections against the These crystals, submitted to measurement by Professor Miller, were obtained by slow spontaneous evaporation: the difficulty of procuring this salt in crystals of any size has been fully pointed out by Mr. Croft. I have only one observation which does not coincide with Mr. Croft's statements, but which, however, confirms in a great measure the results of his analysis; I allude to the statement that these double salts of chromium cannot be formed by the direct combination of their ingredients. The process which I have followed has been to digest the hydrated oxide of chro- mium in a mixed solution of oxalic acid and oxalate of potash in the proportions indicated by analysis, and when it ceases to dissolve the oxide, to decant the clear solution and allow it to crystallize. By the same means the analogous salts of soda and ammonia have been obtained, but not in crystals suffi- ciently large for measurement, as also other double salts of chromium. To prepare the hydrated oxide of chromium, the best and most ceconomical process that I have found, is to take 150 grs. of the bichromate of potash and 200 grs. of liquid sulphuric acid, oil of vitriol, these proportions being nearly in the ratio of their atomic weights, so that the chrome alum, sulphate of the green oxide of chromium and potash, may be formed ; the deoxidation of the chromic acid is easily effected by the addition of a little sugar and boiling the solu- tion. When the deoxidation is complete, the green oxide may be precipitated by ammonia or by a carbonated alkali, and only requires to be well washed to remove all trace of alkali or saline matter. XXXVI. Reply to some Objections against the Theory of Mo- lecular Action according to Newton's Lww. By the Rev. P. Kelland, M.A., F.R.SS. L. $ E., F.C.P.S., &>c, Professor of Mathematics in the University of Edinburgh, late Fellow and Tutor of Queen's College, Cambridge. [Continued from p. 130.] 2. HPHE next objection to the molecular hypothesis of par- -*• tides acting on each other, with forces varying inversely as the square of the distance, is that the equilibrium of such a system would not be stable. This objection is stated by Mr. Earnshawin his memoir, Art. 15. The argument is as follows. The force due to a displacement parallel to either principal axis depends on the second differential coefficient of V, with respect to the coordinate along that axis. Now the sum of the second differential coefficients for the three coordinates is zero. Hence one of them must be positive, and the corre- sponding force put in play acts to draw the particle^owz its system of rest. Of course this reasoning depends on the as- Theory of Molecular Action according to Newton's Law, 203 sumption that — 5, &c. are not zero. In the contrary case, ax1 as Mr. Earnshaw had previously pointed out (Art. 8), " the displacements of particles would not bring into action any forces of restitution." Another part of the objection relates to the boundaries of the medium, or rather of space. " If the particles of aether exert a repulsive action on each other, they will naturally endeavour to disperse themselves throughout all space, and form a medium coextensive with the boundaries of the universe. Here, then, a formidable difficulty presents itself to our notice. If the medium be of finite dimensions it must be inclosed in an envelope capable of restraining the expansive energy of the whole mass of particles. The more extensive the medium, the greater must be the strength of the envelope. Is it probable that the constitution of the universe is such as to require that the whole should be enclosed in a huge vessel of inconceivable strength?" (Art. 20.) The author then goes on to remove the difficulty by assuming a law of force, partly attractive, partly repulsive. In replying to these objections we will reverse their order. a. The difficulty thrown out relative to the equilibrium of the remote parts of space is one which has often presented itself, but from a consideration of which philosophers have, in general, cautiously abstained. The Newtonian system of the universe is beset with difficulties of a similar nature, which, although by no means satisfactorily removed, are never re- garded as subversive of the hypothesis. We must, I conceive, be content with a theory capable of explaining phaenomena which come within the limits of our own observation, without requiring that it should penetrate to the boundaries of the universe, if, in truth, such boundaries exist. I shall consider myself, therefore, at liberty to pass over this objection, with merely requesting that, should it be pressed, I may be informed how it is got over in the Newtonian system. I shall merely add that the molecular hypothesis does not assume that all the particles act with attractive, or all with repulsive forces. b. We proceed to examine the circumstances under which the equilibrium may be neuter. It appears to me that this is really the state of things in nature, and accordingly, when re- plying to Mr. Earnshaw before the Philosophical Society of Cambridge, a little more than two years ago, I argued in support. I then expressed my belief that, in a medium of symmetry, no force whatever is put in play on a particle by its displacement alone. Subsequent investigation has confirmed me in my conjecture. So far as I had proceeded in the in- vestigation I found that V appeared to be constant, so that all 204 Prof. Kelland's Reply to some Objections against the dV d?V d3V the differential coefficients -7-?, -nm t^j &c« are zero; and df djl d/a since the force put in play on a particle by a displacement I dV depends on the expansions of -r-p &c, and therefore of V in terms of 5, it is evident that the force is zero. The equili- brium is consequently what is technically called neuter. The following investigation is copied from the paper above referred to. The complete demonstration of the proposition d"V that , fn is equal to zero, involves some little analysis ; and as it leads to a number of most important results, as, for in- stance, that 2 m (x — /) nf{r) =— 2 m r2"/(r), I will reserve it to my next communication. When V = Sw let V'=Sw 1 •(* -/- uf + (y - g - /3)2 + (z - h - yf a, /3, y being the increments of/5 g3 and h. Now if we put a{x —f) + /3 (3/ — g) + y (z — h) — 6, a2 + /32 + y2 = 8% and expand V, there results _., -,- / 1 2e-82 1.3 (2s-82)2 0 \ W = V + Zm(j —^~ + — ra + &c.) ~V + 2'W1 2r^"+ 2 ? We have obtained our reductions by introducing the results of symmetry. Thus the coefficient of 82 is zero. By pro- ceeding a step further, we get ,1.3.5.7 16 14 , . \ Theory of Molecular Action according to Newton's Law. 205 T \8 r5 12 r5 + !<* a* (« -/)3 + ffl (y-g)* + y4 (*-A)4 + 6a»j3« (x -/)« (y-g)2+&c. 1 105 6 fr -/)« (y - g)« («» |3* + «* y* + /32 y2) & T Now the hypothesis of symmetry, from which we have re- duced the results by making v m (x -ff 1 v r2 fi imposes further the condition that V — V is a function of 8 only, independent of a, /3 and y. Consequently, 2 205 /(x -/)« (g4+i84 + y4) + 6 (x-/)» Q/-g)2i(«2/32 + a2 ?2 + /32y2 \ 24 \ r» / 24 r9 Hence we obtain the equation This equation is of considerable importance. The method by which we have obtained it appears to be totally different from the ordinary methods, such as that employed by Cauchy, Exercises, 3. 201. By substitution The coefficient of S4 depends on the value of But r4 = (* -/J4 + ■ (* - g)4 + (z-h)4 + 2 (x -/)« (y - £)2 + 2 (* -/)» (z - hf + 2 (y - jtf {* - hf ... 3 £ **(*—/)* _ ^ ^ __ 6 j m{x~ff{y-gY = S^-2S?l^l4(byA.)) Hence the coefficient of 84 is zero. 206 Prof. Kelland's Reply to some Objections against the So far, then, as we have proceeded, we have obtained, as our result, that V is constant. We have thus strengthened the argument, if any exists, based on the neutrality of the equilibrium. But what is the argument? Mr. Earnshaw says (Art. 8), " the displacements of particles placed in such positions as those here considered would not bring into action any forces of restoration ; on which account the particles would not vibrate." Mr. O'Brien says, too, " I have shown that if such be the case the whole universe is in a state of neuter equilibrium." [Phil. Mag. June, p. 487.] The only shadow of an argument contained in these quotations exists in the words "on which account the particles would not vibrate." What would they do then? and why? It really is hard that I should be obliged to make the objection's and answer them too. I hope Mr. Earnshaw will point out, in a future communication, whereon he supposes the in- ference to hang. So far as is stated nothing more appears than this : a particle is moved, no instantaneous force is put in play by the motion ; therefore the particle cannot vibrate. Now to this argument we reply, — 1st, that the statement em- bodies a proposition which is very difficult of proof: for although the particle receives no instantaneous force, it cer- tainly communicates one to the adjacent molecules. On those in advance it acts more powerfully, on those behind less so, than when in its position of rest. Motion will therefore ensue. Whether the particles will vibrate or not we do not affirm ; the onus of proving that they will not, rests with those who make the assertion. But 2nd, suppose it could be proved that the particles will not vibrate, what follows? I repeat that we do not attempt to explain how vibrations are generated. It is not to be conceived that the motion of a single particle should produce a system of transverse vibrations; and he who rejects every hypothesis which will not admit such to be the case, excludes virtually (if I mistake not) the possibility of the existence of such vibrations. All that can be made to follow from the above inference, therefore, appears to be, that the motion of a single particle cannot put in play a system of vi- brations. This is a very different thing indeed from what is supposed to be made out by it, viz. " that the constitution of such a medium is incapable of transmitting light, a phaenome- non due to vibration." When it shall have been shown to be incapable of transmitting vibrations, it will be time to reject it; but nothing of the kind has as yet been attempted. c. From what has preceded, it will be evident that we con- ceive the constitution of media to be such that the equilibrium is of the kind technically called neuter ; yet as we are desirous Theory of Molecular Action according to Newton's Law. 207 of saying a few words relative to the argument actually insisted on by Mr. Earnshaw, we propose to examine briefly the con- trary case. Let us suppose the medium unsymmetrical ; and let us further conceive (which by no means necessarily follows) that cPV d?V d?V -T75J -r-n and -=T5 are not zero. Then, as Mr. Earnshaw dfz dg* dhl has proved (Art. 12), there is at least one direction in which, if a particle be moved, the immediate tendency is to cause it to recede further from its position of rest. The consequence will be, either that the other particles by their motion tend to stop it, or that its motion continues. We have no hesitation in affirming that the former is the case. If all the particles commence to move in the same direction, the principle of the conservation of the motion of the centre of gravity will be vio- lated. If, on the contrary, some move in one direction, some in the opposite, there must be vibration unless it can be shown that the particles pass each other. In the latter case there would be perpetual interchange of place amongst the particles. This is certainly very unlikely : but even now admitting the worst we can conceive, the possibility of such a system is not disproved. As it stands at present, I am disposed to think that the objections, based on a want of stability, have rather strengthened than undermined the hypothesis of the inverse square of the distance. The fact, that in a medium of sym- metry the equilibrium is neuter, is a very strong one in favour of the theory. But for this it might have required some violent effort to move a particle at all : as it is, a very slight force will cause motion, so that the medium possesses the character of molecular non-resistance. We do not doubt, however, that there are some difficulties attending this as well as every other theory. To any which may be brought forward I will do my best to reply. I trust that a desire for truth, rather than a love of controversy, will appear in all that shall be said on either side. Since the above remarks were written Mr. Earnshaw has resumed his objections, in a paper which appears in the Phi- losophical Magazine for July. Although all the arguments which appear in that paper have not reference, either to the want of fulfilment of the requisites for vibration, or to the instability of the medium, yet to avoid confusion I propose to reply to them in this place. The consideration of the other two objections placed at the head of this paper will probably demand a more detailed mathematical investigation than could 208 Sir D. Brewster on the Connexion between possibly appear within my present limits, on which account I desire to reserve it to a separate communication. [To be continued.] XXXVII. On the Connexion between the Phenomena of the Absorption of Light, and the Colours of thin Plates. By Sir David Brewster, K.H., LL.D., F.R.S* ^INCE the phenomena of the absorption of light by co- loured media began to be studied with attention, various philosophers have regarded them as inexplicable by the theory of the colours of thin plates, and have consequently regarded Sir Isaac Newton's theory of the colours of natural bodies as either defective in generality, or altogether un- founded. Mr. Delavalf was the first person who brought an extensive series of experiments to bear upon this subject. Dr. Thomas Young J considered it " impossible to suppose the production of natural colours perfectly identical with those of thin plates," unless the refractive density of the particles of colouring bodies was at least twenty or thirty times as great as that of glass or water, which he considered as " difficult to believe with respect to any of their arrangements constituting the diversities of material substances." Sir John Herschel has expressed a still more decided opinion upon this subject. He regards, " the speculations of Newton on the colours of natural bodies" as only " a premature generalization," and *' limited to a comparatively narrow range; while the pha2- nomena of absorption, to which he considers the great ma- jority of natural colours as referable, have always appeared to him to constitute a branch of photology sui generis §." The general opinion advanced by these three philosophers I have long entertained || ; and with the view of supporting them I have analysed a great variety of colours which are ex- hibited by the juices of plants. In a paper " On the Colours of Natural Bodies f ," I have shown that the green colour of plants, the most prevalent of all the colours of natural bodies, in place of being a green of the third order, as Newton and his commentators assert, is a colour of no order whatever, and having in its composition no relation at all to the colours of thin plates. * From the Philosophical Transactions, 1837, p. 245. •f Manchester Memoirs, vol. ii. p. 131. t Elements of Nat. Phil. vol. i. p. 469, 481 ; and vol. ii. p. 638. § Philosophical Magazine, Dec. 1833, S. 3, vol. iii. p. 401. See also his Treatise on Light, Encyc. Metrop., p. 580, 581. || Life of Newton, chap. vii. If Edinb. Trans., vol. xii. [Also Phil. Mag., Third Series, vol. viii. p. 468.] Absorption and the Colours of TJiin Plates. 209 In arriving at these conclusions, however, and drawing a distinct line between the phaenomena of absorption and those of thin plates, two classes of facts are compared under very different circumstances. In the one case philosophers have studied in cumulo the result of the successive actions of an infinite number of the colorific particles upon the intromitted light, whereas in the other case they have observed only the colour of a single particle, whose thickness is equal to that of the films of air, water, glass and mica submitted to experi- ment. The impracticability of combining a number of such films, and studying their united action upon light, was doubt- less the reason which prevented natural philosophers from bringing the two series of facts under the same conditions. Sir Isaac Newton, indeed, had spoken so confidently of the result of such a combination, as to discourage any attempts to effect it ; and it is a singular fact that his successors have never called in question his bold though ingenious assump- tion. " If a thinned or plated body," says he, " which being of an even thickness, appears all over of an uniform colour, shall be slit into threads or broken into fragments of the same thickness with the plate, I see no reason why every thread or fragment should not keep its colour, and by consequence why a heap of those threads or fragments should not constitute a mass or powder of the same colour which the plate exhibited before it was broken. And the parts of all natural bodies being like so many fragments of a plate, must on the same grounds exhibit the same colours." This remarkable opinion I have often been desirous to sub- mit to the test of direct experiment, in the conviction that the result would be different from what is here stated ; but I have been baffled in every attempt to make such an experiment ; and had not accidental circumstances placed in my hands two substances in which thin plates were combined nearly in the very manner which I wished, and which I believe had never before been submitted to examination, the problem might have remained long without a solution. The first of these substances to which my attention was called, is the remarkable nacreous body which Mr. Horner has described in the last volume of the Transactions, and whose singular optical properties I have explained in a letter which accompanies his paper. This substance consists of laminae of considerable transparency, separated by extremely thin films, which exhibit in the most brilliant manner the co- lours of thin plates. In order to compare the effect produced by a number of such films with that of a single film, we must either analyse Phil. Mag. S. 3. Vol. 21 . No. 1 37. Sept. 1 84-2. P 210 Sir D. Brewster on the Connexion between the light reflected and transmitted by a single film by means of a fine prism placed in front of a telescope, or examine the prismatic spectrum produced by such an apparatus when it is reflected or transmitted by the film in question. When we thus examine the reflected tints of the three first orders of colours, we find them to consist of that part of the spectrum which gives the predominating colour of the tint mixed with the rays on each side of it. The reflected green of the third order, for example, consists of the green part of the spectrum, bounded on one side with some blue, and on the other side with some yellow rays, all the rest of the spectrum being wanting, having passed, as it were, into the transmitted beam. In analysing, therefore, the transmitted beam, its spectrum is found to con- sist only of the violet and blue, and the orange and red spaces, a dark band corresponding to the reflected spectrum separa- ting it into two parts. In the higher orders of colours the reflected spectrum consists of two or more portions separated by perfectly dark bands, while the transmitted light exhibits analogous bands, which are much less dark in consequence of the tint being diluted with a portion of white light. The coloured bands of the reflected spectrum occupy the same place among the fixed lines of the spectrum as the dark bands of the transmitted one ; and if the two spectra were superposed they would form a perfect spectrum, whose rays when united would form white light. Hence the reflected and the trans- mitted tints are complementary to each other. When this analysis is made with a highly magnified spec- trum, the numerous lines of which are distinctly seen, it forms one of the most splendid experiments in optics. The spectrum is crossed throughout its whole extent with alternate dark and coloured bands, increasing in number and diminish- ing in magnitude with the thickness of the plate by which the tint is produced. If we use a thin film of mica, of such a thickness as polar- izes the isohite of the first order, the transmitted spectrum will be crossed by upwards of three hundred dark and three hun- dred luminous bands, thirty-four of each being included be- tween the lines C and D of Fraunhofer, a space less than one tenth of the whole spectrum. W7hen we use polarized light, and interpose a doubly re- fracting plate, and subsequently analyse the transmitted beam, the spectrum is crossed with an analogous series of bands, which are still more splendid and more perfect than those given by a singly refracting film. The bands in the comple- mentary spectra are equally and perfectly dark; and when the tints are pure as in calcareous spar, the colours are nearly Absorption and the Colours of Thin Plates. 211 identical with those of thin plates. Through the natural faces of a rhomb of calcareous spar about one sixth of an inch thick, I observed in the space C D above mentioned hundreds of the most minute lines almost as sharp and black as those in the solar spectrum. In the phaenomena of periodical colours which we have now described, there are three peculiarities which demand our attention. 1. The dark lines change their place by in- clining the plate which produces them. 2. Two or more lines never coalesce into one, and one line of the series is never seen without all the rest being equally visible. 3. The colours of the luminous bands in the complementary spectra are the same as those of the original spectrum when the thin plate is perfectly colourless. In the case of polarized tints this simi- larity is not general. In order to obtain a correct idea of the phaenomena of ab- sorption, I shall describe those which are exhibited by a solid, & fluid, and a gaseous body, — by the common smalt blue glass, by the green sap of vegetables, and by nitrous acid gas. Dr. Young has described the smalt blue glass as dividing the spectrum " into seven distinct portions." I have given in the Edinburgh Transactions* rude coloured drawings of the effect it produces on the spectrum, and Sir John Herschelf has represented its action in a different manner. Excepting in the single circumstance of the spectrum being divided into bands, there appears no analogy whatever between this phae- nomenon and those of thin plates. The bands diminish in number as the thickness of the plate increases, and their co- lour suffers no other change by inclining the plate but that which arises from the small increase of thickness which the ray traverses. There is one remarkable point of difference between the two classes of phaenomena which requires to be specially attended to. The colours of some of the luminous bands are not the same as those of the spectrum, and therefore the glass has removed certain colours while it has left others of exactly the same refrangibility. The green, for example, is changed into yellow by the removal of blue rays, and in certain glasses a band, almost white, is produced. The co- lours thus removed are said to be absorbed; and by an exten- sive series of experiments with such absorbing substances I have been able to insulate white light in the spectrum, which no prism can decompose, and to establish the existence of three equal and superposed spectra of red, yellow and blue light. Analogous phaenomena are exhibited in an alcoholic solu- * Vol. jx. p. 439. pi. xxvii. f Ibid. p. 449. pi. xxviii. P2 212 Sir D. Brewster on the Connexion between tion of the colouring matter of the green leaves of vegetables. The spectrum which it forms consists of six luminous bands, separated by five dark ones*, and the phaenomena have the same character as those of the blue glass. When the spectrum is viewed through nitrous acid gas the phaenomena are still more remarkable. While the gas exerts a general absorbent action over the violet extremity of the spectrum, it attacks it when in a diluted state in definite lines as sharp and distinct as those in the solar spectrum ; and what is still more important, it acts upon the same parts of light as the cause which produces the fixed lines in the sun's spec- trum. In other respects the character of its action is similar to that of the blue glass and the green sap of plants. In thus comparing the phasnomena of absorption with those of thin plates, we find no connecting link but that of giving a divided or a mutilated spectrum ; and even this common fact has not the same character in both. In coloured media the bands of light and darkness have no fixed relation, as in periodical colours; and the light removed from the dark por- tions, as well as the tints from some of the coloured spaces, have wholly disappeared, in place of being found in the re- flected beam. I have already mentioned, that by the aid of two substances I have been able to study this subject under a new aspect, and that the nacreous substance described by Mr. Horner was the one which first exhibited to me the connexion between absorption and periodical action. This substance when it contains no thin plates acts generally in absorbing the violet and blue end of the spectrum; but when it includes within it, or has on its surface thin films which act like thin plates, it exercises an additional 'action upon the spectrum. In some cases when the thickness of the plate is small, it produces bands perfectly identical with those of thin plates, but in other cases the bands are exactly similar to those of coloured media. In one specimen I obtained a dark and distinct band in the orange space at D, with another feint band in the red. These bands were parallel to the fixed line D at a vertical incidence, but by inclining the plate the bands moved towards the green space, and became inclined to the line D. In a recent specimen I obtained the darkest band in the green space, with other lesser bands of unequal size and breadth in the other spaces, all of which moved along the spectrum, while new ones advanced from the red ex- * A full account of this experiment, and a coloured drawing of the di- vided spectrum, will be found in the Edinburgh Transactions, vol. xii. Absorption and the Colours of Thin Plates. 2 1 3 tremity during the inclination of the plate. In a third specimen the phaenomena were still more varied, and what was a new feature in the results, the colour of the tints was changed exactly as in the phaenomena of absorption. It is very obvious that these results are not produced by the same action which causes the orange colour of the substance, for this action could not vary by the inclination excepting in producing a greater ab- sorption of the more refrangible rays ; but in order to place this beyond a doubt, I detached a film which had none of the colours of thin plates, and which, as I expected, produced' none of the bands above described. In these experiments the nacreous plate was placed in Canada balsam to remove the imperfect smoothness of its surface, but the phasnomena were essentially the same with plates surrounded by air. I now divided the first of the plates above mentioned into two, and having viewed the spectrum through both, I found the principal black band considerably widened, as happens with absorbent media. When the light reflected from the nacreous plates is ex- amined in a similar manner, the division of the spectrum into bands is extremely brilliant and beautiful, and the phaeno- mena the same ; but owing to the light having entered the substance to different depths before it was reflected, the spec- trum is by no means complementary to the one seen by trans- mission. Satisfactory as these experiments are, I was still desirous of obtaining similar results with perfectly transparent plates ; but after failing in every attempt to combine them, I thought of trying the iridescent films of decomposed glass*. This idea succeeded beyond my most sanguine expectations. I obtained combinations of films which gave me by transmitted light the most rich and splendid colours, surpassing anything that I had previously seen either among the colours of nature or of art. I obtained the deepest and richest blues shading off into the palest, and the finest reds and yellows, with all those intermediate and mixed tints which are seen only in the vegetable kingdom. The reflected tints had quite a different character. They possessed all the brilliancy of metallic re- flexion, like the colours in the Diamond Beetle and other in- sects, and the tints varying within a considerable range were disposed in straight lines and bands, as if the film had formed part of a regularly organized bodyf. * For a very fine collection of these films I have been indebted to the kindness of Mrs. Buckland, theMarquis of Northampton, and Mr.Children. t The surface of these films is beautifully mammillated, the parts that are curves on one side being concave on the other. 214 Sir D. Brewster on the Connexion bePweqn The reflected tints of course vary with the obliquity of the incident light ; and at great incidences the transmitted ones, however splendid and varied, all become pale yellow. When these combinations of glass films are immersed in a balsam or an oil, their colours, whether transmitted or reflected, all dis- appear, excepting a pale yellow light like that which is trans- mitted at great incidences. These facts prove, beyond a doubt, that the transmitted colours, though wholly unlike to those of thin plates, are yet produced by the same cause, and are residuary, and generally complementary to the hue of the reflected tints. The analysis of these colours by the prism affords a series of most beautiful and instructive phaenomena, and it is only by coloured drawings that any adequate idea of them can be conveyed. All the phenomena of coloured media, with bands of various breadths and various intensities of illumination, are exhibited in great perfection, so as to identify completely in this feature the two classes of facts. But what is still more striking, the colours of the bands are changed, and we thus find that the characteristic phaenomenon of absorption is pro- duced by the action of thin plates. To such a degree indeed is the change of tint carried, that I have insulated a white band in the orange part of the spectrum. 9 Notwithstanding this identification of absorption and pe- riodical action in their primary features, there are two points of difference which separate widely the two classes of phaeno- mena : the first of these is, that the bands and tints of ab- sorbing media are not changed by obliquity; and the second, that the reflected tints are not visible in such media. Sir Isaac Newton endeavoured to remove the first of these diffi- culties by supposing that the particles of bodies on which their colours depended have an enormous refractive power ; and M. Biot * has endeavoured to meet it more effectually by introducing two new suppositions ; viz. that the particles are capable of transmitting light only through their centre of gra- vity, and that the lateral transmissions may be prevented or turned aside by the inflecting forces which act at a distance on the luminous molecules which approach them. These explanations of the uniformity of the tints at all in- cidences have been rendered necessary, not perhaps by the real difficulties of the case, but in consequence of Sir Isaac Newton and his followers taking it for granted that the co- lours of natural bodies were pure tints of a particular order. Hence it becomes a necessary assumption in the theory that * Traite de Physique, torn. iv. p. 126. Absorption and the Colours of Thin Plates. 215 the particles had sizes corresponding to these pure tints, and that the light which composed them should not pass through different thicknesses of these particles. As I have demon- strated, however, in a paper already referred to, that the tint which Newton reckoned one of the third order, has no con- nexion whatever with that or with any other order, and that all other tints of absorbent media are in the same predica- men;, we are not only free from the difficulty which embar- rassed Newton ; but it is actually necessary to have recourse to particles of an ordinary refractive power, and having such forms and occupying such positions as will permit lateral transmissions and thus produce compound tints, such as we actually observe in natural bodies, and as we have shown to be produced by thin plates. Now if we suppose the colouring particles to be spherical, or to have the form of plates or cubes, or other solids dissemi- nated through the fluid or solid bodies which they colour, the tints would be permanent and compound as we find them in nature. The second point of difference to which I have referred, namely, the absolute disappearance of the reflected tints in several coloured solids, fluids, and gases, is one of great mag- nitude. Newton has evaded this difficulty in his theory ; but from the manner in which he gets rid of the intromitted light in black bodies, it is obvious that he would ascribe the dis- appearance of the reflected tints to their being " variously reflected to and fro until they happened to be stifled and lost." As I shall have occasion to discuss this subject experiment- ally in a paper on the permanent colours of natural bodies, I shall only state at present that I have succeeded by particular methods in rendering reflected tints visible in many coloured fluids and glasses, but 1 cannot consider them as equivalent to the reflections of thin plates. I have endeavoured to corroborate the views contained in the. preceding pages by a series of collateral experiments on the periodical colours of polarized light. When we divide the spectrum into bands by doubly refracting plates, the phae- nomena are beautiful beyond all description. If we dissect or subdivide the luminous bands in the spectrum, as seen by one analysing prism, by means of successive plates and prisms, the result is very remarkable; and if the doubly refracting, plates are inclined to each other or to the incident beam, the black bands will also be inclined to each other, and the lu- minous spaces have the form of a triangle either complete or truncated at its apex. By using plates of the same or of va- 216 On Absorption and the Colours of lliin Plates. rious substances *, and placing their axes in different azi- muths to the plane of primitive polarization, we obtain ex- tremely singular spectra, in which the bands approximate to those of absorbing media. But there is another result of this class of experiments to which I would especially call the attention of philosophers. The colours of the bands thus produced have no resemblance to those of the original spectrum, so that the spectrum has actually been analysed by dissection. This effect is so de- cided, that even by a single subdivision of a banded spectrum I have succeeded in insulating a band nearly white, and of course incapable of being decomposed by the prism. Hence we deduce from the phenomena of thin plates, and polarized tints, the existence of a new property of light, in virtue of which the reflecting force selects, as it were, out of differently coloured rays of the same refrangibility rays of a particular colour, allowing the others to pass into the trans- mitted beam ; or to use the language of the undulatory theory, the colour produced by the interference of homogeneous pen- cils reflected from the first and second surfaces of thin plates, is different from the colour produced by the interference of the transmitted light with that which has suffered two inter- nal reflexions within the plate. If, for example, we use the greenish yellow light of the spectrum between the lines D and E, the system of reflected rings will be more yellow than the transmitted rings towards E, and more green than the same rings towards D ; a result, which, in so far as the transmitted tints are concerned, is seen in the colours of smalt blue glass. Here then we have a principle not provided for in either of the theories of light to which the phaenomena of absorption, * I have constructed apparatuses of this kind made out of composite crystals of calcareous spar, including one and more thin plates of its own substance. The beautiful and apparently capricious tints which such cry- stals exhibit when properly cut into prisms, or when prisms are applied to their surface, are nothing more than the luminous bands of the spectrum subdivided by one or more dissections. I have now before me such a cry- stal, in which a prism cemented externally brings out the spectrum, which would otherwise have suffered total internal reflexion. A virtual prism forming part of the rhomb polarizes the incident light, an included hemi- trope plate affords the polarized tints, and a second virtual prism analyses the light which the plate transmits. In some parts of the rhomb there are plates of different thickness, by which the luminous bands are beautifully subdivided. In this manner, by the slight aid of an applied prism, we are •furnished with a complicated optical apparatus. Such a combination, which it is easy to make artificially by inclosing thin doubly refracting plates between prisms of calcareous spar, affords an ocular explanation of those beautiful forms of the system of' polarized rings which are produced in composite crystals of calcareous spar. These subdivided bands, indeed, are portions of that system seen obliquely by prismatic refraction. Mr. Earnshaw on Dispersion, in reply to Prof. Powell. 217 produced by nacrite, by decomposed films of glass and by polarizing plates, are distinctly referable. Here also we have the probable cause of certain remarkable phenomena of di- chroism in doubly refracting bodies, in which rays of the same refrangibility, but of different colours, pass into the ordinary and extraordinary pencils. Allerly, May 5th, 1837. XXXVIII. On the Theory of the Dispersion of Light; in reply to Prof. Powell's Note. By S. Earnshaw, M.A., Cambridge*. T^HE object which I had in view in writing the letter printed -* in your Magazine for April, was to show that the " op- probrium of all theories, — the dispersion of light," — has not yet been removed from the undulatory theory. I endeavoured to accomplish this object by showing two things ; — 1st, that a certain formula, derived directly from theory, which was said to have supplied " both the laws and the explanation of the phenomena of dispersion," is insufficient for that purpose ; and 2ndly, that the method of calculation employed in com- piling the tables given in Professor Powell's book is a method of interpolation only, and therefore from its very nature inca- pable of verifying a physical theory of dispersion. It is not necessary to repeat the arguments by which I endeavoured to establish these two points. In answer to the former, the Professor distinctly states that he has "long since discarded " the formula animadverted upon ; and therefore I suppose that, as far as that formula is concerned, I may consider the object of my letter accomplished. In answer to the remaining parts of my letter, the Professor, if I rightly understand his note, puts forward three arguments : — 1st. That Sir W. R. Hamilton has taken the trouble of simplifying the mode of calculation, a circumstance which im- plies his approval of the general principle. 2ndly. That that " pre-eminently gifted mathematician M. Cauchy " has considered his own investigations a suffi- cient basis for calculation ; and, 3rdly, That the method of calculation used in computing the tables " is surely, at all events, a direct deduction from theory." Now I will not accuse Professor Powell of bringing forward the first two of these with the intention of carrying the dis- puted point by the force of great names; but if such had been his intention, they are, as it seems to me, better suited for * Communicated by the Author. 218 Mr. Earnshaw on Dispersion) in reply to Prof. Powell. that mode of argument than for fair philosophical discussion. I am willing to pay my humble tribute to the merits of the two eminent philosophers quoted; but the matter in dispute between Professor Powell and myself lying entirely within the limits of my own reading and understanding, it is not likely that I shall be convinced by any other than a fair appeal to philosophical argument. With respect to the Professor's third argument, it appears to me to assume too much. It ought to have been shown that theory has done more for the series (upon which the cal- culations are founded) than merely to indicate that it must proceed according to inverse powers of A ; for if it has, not done more than this, it has in effect done nothing. But even granting that there is something meritorious in the form of the suggested series, I would beg the Professor's attention to two of my objections which still remain in force; — 1st, that the mode of applying it to calculation disconnects it from theory, by rendering the method one of ordinary interpola- tion : and 2ndly, that the results obtained do not coincide sufficiently with experiment to warrant us in concluding from them that the form of the series furnished by theory is the correct one. Before I conclude it is necessary to advert to two other matters : the Professor seems to consider that I have used him unfairly in not distinguishing between " certain earlier researches " and those contained in his " published volume." If the Professor will turn again to my letter (p. 309) he will there read that the errors of which I had been speaking, are charged only upon " the first applications of the method." I trust therefore he will be satisfied that I am not guilty of the unfairness of which he complains, and have not committed those " remarkable oversights " of which he (somewhat un- fairly I think) accuses me. And with respect to his having discarded his earliest researches, — " the simple circumstance which renders all my elaborate criticisms superfluous," — I do not regard it as being by any means so fatal to my letter as the Professor seems to think it is : for if he will do me the favour to refer to my letter again he will find that the first part only was directed against the " superseded re- searches," the second part he will find summed up in these words : " the methods of computation employed in compiling the tables contained in the book referred to are wholly un- connected with a physical theory of dispersion, and therefore were they even coincident with experiment add nothing to the strength of M. Cauchy's theory ; and were they even more dis- cordant than they are with experiment, tend in no degree to Mr. H. A. Goodwin on a Property of the Parabola. 219 overturn it." But supposing that my criticisms upon " the published volume" could be set aside by the Professor's aban- donment of his earliest researches, I think in having produced a distinct public declaration of this fact it has done service to science, and therefore to that extent my desire has been ac- complished, for it cannot be said that there is in the published volume any statement to the effect that those researches were to be considered as superseded by the book ; so far otherwise indeed, that we are told in the introduction that it is sent forth " partly as a resume of previous researches which have from time to time appeared, and partly as supplying what was wanting to complete them," and more than once the early re- searches are referred to in terms of approval. It is clear therefore that without a distinct declaration, such as my letter has drawn forth, neither I nor any other person would have been justified in treating as discarded the researches in which the author has stated it to be his opinion that " the refractive indices are related to the lengths of waves, as nearly as pos- sible according to the formula deduced from M. Cauchy's theory." August 11, 1842. XXXIX. Proof of Professor Wallace's Property of the Pa~ rabola. By Henry Albert Goodwin, Esq.* To the Editors- of the Philosophical Magazine and Journal. Gentlemen, TF the accompanying proof of Professor Wallace's property of the parabola appears to you to have any advantage over former solutions in symmetry and conciseness, it is much at your service. My object in offering it is to exemplify the great use of the simple equation to the tangent, which I have used, and because the method employed brings out the result in a most direct manner. I am, Gentlemen, yours obediently, Corpus Christi College, Henry Albert Goodwin. Cambridge. Let aj a2«3 be the tangents of the As which the three tan- gents make with the axis of x. The equations to these tan- gents are ^ = «i *+—(!•) 3/ = "2*+ — (2-) = ■ l ,£, which by reduction from (4.) and (5.) manifestly becomes "i-g3 (l+a22) tan

is clearly supplementary to the angle between tan- gents (1.) and (3.), and the circle described about the A formed by the tangents (1.) (2.) (3.) will of course pass through the focus. XL. Proceedings of Learned Societies. ROYAL SOCIETY. (Continued from p. 55.) May 5, 1842* \ PAPER was also read, entitled, "On Fibre:" (Continued.) -£*• additional observations. By Martin Barry, M.D., F.R.S., Lond. and Ed.f On examining coagulating blood, the author finds that it contains discs of two different kinds ; the one comparatively pale ; the other, very red. It is in the latter discs that a filament is formed ; and it is these discs which enter into the formation of the clot ; the former, or the pale discs, being merely entangled in the clot, or else remain- ing in the serum. He thinks that the filament escaped the notice of former observers, from their having directed their attention almost exclusively to the undeveloped discs which remained in the serum, * For abstracts of the other papers read on May 5th and 12th, see p. 54. — Edit. t We are requested by Dr. Barry to add the following as a correction of the fifth paragraph in the above abstract. That the corpuscles of the blood are reproduced by means of parent- cells, and by division of their nuclei, he had recorded, not as conjectures, but as observed facts. (See Phil. Trans., 1841, p. 204 and 244, pi. xviii.) Dr. Barry's previous observations on Fibre will be found in our last volume, p. 321, 344. — Edit. Royal Society. 221 and thus conceived that the blood-discs are of subordinate import- ance, and are not concerned in the evolution of fibrin. To render the filament distinctly visible, Dr. Barry adds a chemi- cal reagent capable of removing a portion of the red colouring matter, without altogether dissolving the filament. He employs for this purpose chiefly a solution of one part of nitrate of silver in 120 parts of distilled water ; and sometimes also the chromic acid. He admits that the use of these reagents would, on account of their destructive tendency when concentrated, be objectionable as proofs of the absence of any visible structure ; but as the point to be proved is that a certain specific structure does exist, he contends that the same appearance would not equally result from the chemi- cal actions of reagents so different as are those of chrome and the salts of mercury and of silver. After the appearance of the fila- ment, thus brought to light, has become familiar to the eye, it may be discerned in the blood-discs, when coagulation has commenced, without any addition whatever. Those blood-discs of the newt, which contain filaments, often assume the form of flask-like vesicles, the membranes of which exhibit folds, converging towards the neck, where, on careful examination, a minute body may be seen pro- truding. This body is the extremity of the filament in question, its protrusion being occasionally such as admit of its remarkable struc- ture being recognised. The author proceeds to describe various appearances which he has observed in the coagulum of the blood, and which strongly re- semble those met with in the tissues of the body, and are obviously referable to a similar process of formation. He bears testimony to the accuracy of the delineations of coagulated blood given by Mr. Gulliver. One of the most remarkable phamomena discovered by the author in the coagulation of the blood is the evolution of red colouring matter ; a change corresponding to that which he had previously observed to take place in the formation of the various structures of the body out of the corpuscles of the blood. He con- siders the production of filaments as constituting the essential cir- cumstance in coagulation. He conjectures that the notched or granulated fibres noticed in the blood by Professor Mayer, may have been of the same kind as the flat, grooved, and compound filaments described by himself; but he thinks that, in that case, Mayer's explanation of their mode of origin must be erroneous ; for they may be seen to be produced by a portion of the blood not mentioned by him, namely, the corpus- cles. Mr. Addison's discovery of globules in the uppermost stratum of inflammatory blood, and of their influence in the formation of the buffy coat, is confirmed by Dr. Barry, who remarks that these glo- bules are altered red blood-discs. That the blood corpuscles are reproduced by means of parent-cells, as suggested by Mr. Owen and by the author, is confirmed by the observations of Dr. Remak ; but the author had long ago indicated a division of the nucleus as being more particularly the mode of reproduction, not only of those 222 Royal Society, corpuscles, but of cells in general. With this conjecture the obser- vations of Reraak on the blood-corpuscles of the foetal chick fully accord. Whether the author's further speculation, namely, that the parent-cells are altered red blood-discs, is correct, still remains to be seen. The phenomenon of the " breaking off short," or notching of the fasciculus of a voluntary muscle in a transverse cleavage of the fibre, is regarded by Dr. Barry as a natural consequence of the in- terlacing of the larger spirals, which he has described in a former paper ; the fracture, in proceeding directly across the fasciculus, taking the direction in which there is least resistance. The position of the filament in the blood-corpuscle is represented as bearing a striking resemblance to that of the young in the ovum of certain intestinal worms, the filaments of which are reproduced by spontaneous division. The author subjoins the following quaere, " Is the blood-corpuscle to be regarded as an ovum ?" May 12. — The following papers were read, viz.->- " Barometrical Observations, showing the effect of the Direc- tion of the Wind on the Difference between distant Barometers." By Lieut.-Colonel Philip Yorke, S. F. Guards. Communicated by Lieut.-Colonel Sabine, R.A., F.R.S., &c. The author institutes a comparison between the barometric heights as observed at the Apartments of the Royal Society, and at his house in Herefordshire, in the neighbourhood of Ross, with a view to as- certain the influence of prevailing winds on the atmospheric pressure. The barometers thus compared together were of the same construc- tion, and by Ihe same maker; and the times of observation, namely nine o'clock a.m. and three o'clock p.m., were the same at both places, the distance between which is 1 1 0 miles in longitude, and about 20 in latitude. The degree of accordance in the march of the two barome- ters is exhibited by that of curves traced on three sheets accom- panying the paper. The results are given in eight tables. The au- thor agrees with Schubler in ascribing the currents prevailing in the atmosphere to the variable relations of heating and cooling which obtains between the Atlantic Ocean and the continent of Europe at different seasons ; the facts ascertained by the series of observations here presented being in accordance with that hypothesis. If the northerly and westerly winds in England be partly the effect of the expansion of the air on the continent, then the barometer which is nearest to the continent, or in this instance that at London, ought to be relatively more depressed than the one more distant; or if the southerly and easterly winds be regarded as proceeding to the ocean, then, for a similar reason, the barometer nearest to the ocean ought to be relatively depressed ; and that both these effects are produced, is shown by the tables. This view of the subject also, the author remarks, is corroborated by Raymond's observations, detailed in his memoir on the determination of the height of Cler- mont Ferrand, from which it appears that with the north winds, the southern barometer was most depressed ; while the reverse occurred with the southerly winds. Royal Society. 223 May 26. — A paper was in part read, entitled, " On the Transpa- rency of the Atmosphere, and the Law of Extinction of the Solar Rays in passing through it." By James D. Forbes, Esq., F.R.S., Sec. R.S. Edinb., Professor of Natural Philosophy in the University of Edinburgh. June 2. — The reading of Prof. Forbes's paper was resumed and concluded. This paper is divided into seven sections. In the first, the qua- lities of heat and light are considered in as far as they modify the comparability and absolute nature of our measures of the influence of the solar rays. All instruments, whether called Tfiermometers, Photometers, or Actinometers, measure but the peculiar effect to which their construction renders them sensible, but are incompetent to give absolute measures of either heat or light. The second section treats of the history of the problem of the law and measure of extinction of the solar rays in passing through the atmosphere of the earth in clear weather. The labours of Bouguer, Lambert, De Saussure, Leslie, Herschel, Kamtz and Pouillet are successively passed under review, and their instrumental methods considered. In the third section, a mathematical problem of considerable dif- ficulty and interest is investigated ; principally after the manner of Laplace. It consists in the determination of the length of the path and the mass of air which a ray of light must traverse in passing through the earth's atmosphere at every different angle of obliquity. The author determines the numerical value of these quantities for all angles of incidence from 0° to 90°. The fourth section contains an account of the observations made by the author in conjunction with Professor Kamtz in 1832. These were conducted in 1832 at the top and bottom of the Faulhorn, a mountain of the canton of Berne in Switzerland. The lower station was Brientz, and the intercepted stratum of air had 6800 English feet of thickness, corresponding in its weight to about one-fourth of the entire atmosphere. Frequent observations were simultaneously made with the actinometer and other meteorological instruments at both stations, and the loss of solar heat in passing through the in- tervening mass of air was thus directly determined. In the fifth section, the observations made from sunrise to sunset, on one peculiarly favourable day (the 25th September, 1832), are carefully analysed; and from the absorption at various obliquities, the law of extinction in the atmosphere, within the limits of obser- vation, is attempted to be deduced. The sixth and seventh sections include the results of similar, but less perfect observations in 1832 and in 1841. From the facts and reasonings of this paper, the author deduces, on the whole, the following conclusions : — 1. The absorption of the solar rays by the strata of air to which we have immediate access is considerable in amount for even mo- derate thicknesses. 2. The diurnal curve of solar intensity has, even in its most nor- 224 Royal Society. mal state, several inflections ; and its character depends materially on the elevation of the point of observation. 3. The approximations to the value of extra- atmospheric radia- tion, on the hypothesis of a geometrical diminution of intensity, are inaccurate. 4. The tendency to absorption through increasing thicknesses of air is a diminishing one ; and in point of fact, the absorption almost certainly reaches a limit beyond which no further loss will take place by an increased thickness of similar atmospheric ingredients. The residual heat, tested by the absorption into a blue liquor, may amount to between half and a third of that which reaches the sur- face of the earth after a vertical transmission through a clear at- mosphere. 5. The law of absorption in a clear and dry atmosphere, equiva- lent to between one and four thicknesses of the mass of air traversed vertically, may be represented, within those limits, by an intensity diminishing in a geometrical progression, having for its limit the value already mentioned. Hence the amount of vertical transmis- sion has always, hitherto, been greatly overrated ; or the value of extra-atmospheric solar radiation greatly underrated. 6. The value of extra-atmospheric solar radiation, on the hypo- thesis of the above law being generally true, is 73° of the actino- meter marked B 2. The limiting value of the solar radiation, after passing through an indefinite atmospheric thickness, is 15° 2'. 1. The absorption, in passing through a vertical atmosphere of 760 millimeters of mercury, is such as to reduce the incident heat from 1 to 0-534. 8. The physical cause of this law of absorption appears to be the non-homogeneity of the incident rays of heat, which, parting with their more absorbable elements, become continually more per- sistent in their character ; as Lambert and others have shown to take place, when plates of glass are interposed between a source of heat and a thermometer. 9. Treating the observations on Bouguer's hypothesis of a uniform rate of extinction to the intensity of the incident rays, the author obtains for the value of the vertically transmitted shares of solar heat in the entire atmosphere, — By the relative intensities at Brientz and the Faulhorn... 0*6842 By the observations at the Faulhorn alone, — First method 0*6848 Second method 0*7544 By the observations at Brientz alone, — First method 0*7602 ' Second method 0*7827 June 9. — A paper was read, entitled, " On the Specific Inductive Capacities of certain Electric Substances." By William Snow Har- ris, Esq., F.R.S. The author, pursuing the experimental inquiry suggested by the theory of Mr. Faraday relative to the differences in specific induc- tive capacity exhibited by different dialectric substances, instituted Action of the Solar Spectrum on Vegetable Colours. 225 a series of experiments for determining with precision their compa- rative powers of insulation, and of sustaining by induction charges of electricity. The substances to be examined were cast into the form of circular plates and furnished on both their surfaces with circular coatings of tinfoil of a diameter equal to one-half that of the plate, and the electric intensities were measured by electrometers of the same construction as those which he used in his former experiments, and which he has described in his paper* already published in the Philosophical Transactions for 1859. The results are stated in ta- bles ; from the last of which it appears that the inductive capacities of the dialectric bodies tried, that of air being expressed by unity, are proportional to the following numbers : — Substances. Relative capacities. Air 1 Rosin 1*77 Pitch 1-8 Bees' wax 1*86 Glass 1-9 Brimstone 1*93 Shell-lac 1-95 The author, in conclusion, offers some observations on the expe- rimental processes employed in his investigation ; and points out several circumstances which require to be attended to in order to ensure success. June 16. — The following papers were read, viz. — 1. " On the Action of the Rays of the Solar Spectrum on Vegetable Colours." By Sir John F. William Herschel, Bart., K.H., F.R.S. The author, having prosecuted the inquiry, the first steps of which he communicated in a paper read to the Royal Society in February 1 84-Ot, relating to the effects of the solar spectrum on the colouring matter of the Viola tricolor, and on the resin of guaiacum, re- lates, in the present paper, the results of an extensive series of simi- lar experiments, both on those substances, and also on a great number of vegetable colours, derived from the petals of flowers, and the leaves of various plants. In the case of the destruction of colour of the pre- parations of guaiacum, which takes place by the action of heat, as well as by the less refrangible rays of light, he ascertained that although the non-luminous thermic rays produce an effect, in as far as they communicate heat, they are yet incapable of effecting that peculiar chemical change which other rays, much less copiously en- dowed with heating power, produce in the same experiment. He also found that the discoloration produced by the less refrangible rays is much accelerated by the application of artificial terrestrial heat, whether communicated by conduction or by radiation ; while, on the other hand, it is scarcely or not at all promoted by the purely thermic rays beyond the spectrum, acting under precisely similar cir- cumstances, and in an equal degree of condensation. The author proceeds to describe the photographic effects produced on papers [* Noticed in Phil. Mag., Third Series, vol. xv. p. 320— Edit.] [f An abstract of the paper here referred to will be found in Phil. Mag., Third Series, vol. xvi. p. 331. — Edit.] Phil. Mag. S. 3. Vol. 21. No. 137. Sept. 1842. Q 226 Royal Society. coloured by various vegetable juices, and afterwards washed with various solutions. The action of solar light he found to be exceed- ingly various, both as regards its total intensity and the distribution of the active rays over the spectrum. He observed, however, that the following peculiarities obtain almost universally in the species of action exerted on vegetable colours. First, the action is positive ; that is to say, light destroys colour, either totally, or leaving a residual tint, on which it has no further, or a very much slower action ; thus effecting a sort of chromatic ana- lysis, in which two distinct elements of colour are separated, by de- stroying the one and leaving the other outstanding. The older the paper, or the tincture with which it is stained, the greater is the amount of this residual tint. Secondly, the action of the spectrum is confined, or nearly so, to the region of it occupied by the luminous rays, as contra-distinguished both from the so-called chemical rays beyond the violet, (which act with chief energy on argentine compounds, but are here for the most part ineffective,) on the one hand, and on the other, from the thermic rays beyond the red, which appear to be totally ineffective. Indeed, the author has not hitherto met with any instance of the extension of this description of photographic action on vegetable colours beyond, or even quite up to the extreme red. Besides these, the author also observed that the rays which are effective in destroying a given tint, are, in a great many cases, those whose union produces a colour complementary to the tint destroyed, or at least one belonging to that class of colours to which such com- plementary tint may be referred. Yellows tending towards orange, for example, are destroyed with more energy by the blue rays ; blues by the red, orange and yellow rays ; purples and pinks by yellow and green rays. These phenomena may be regarded as separating the luminous rays by a broadly defined line of chemical distinction from the non-luminous ; but whether they act as such, or in virtue of some peculiar chemical quality of the heat which accompanies them as heat, is a point which the author considers his experiments on guaiacum as leaving rather equivocal. In the latter alternative, he observes, chemists must henceforward recognize, in heat from dif- ferent sources, differences not simply of intensity, but also of quality ; that is to say, not merely as regards the strictly chemical changes it is capable of effecting in ingredients subjected to its influence. One of the most remarkable results of this inquiry has been the discovery of a process, circumstantially described by the author, by which paper washed over with a solution of ammonio-citrate of iron, dried, and then washed over with a solution of ferro-sesquicyanuret of potassium, is rendered capable of receiving w^th great rapidity a positive photographic image ; and another in which a picture nega- tively impressed on a paper washed with the former of these solu- tions, but which originally is faint and sometimes scarcely percep- tible, is immediately called forth on being washed over with a neutral solution of gold. The picture does not at once acquire its full intensity, but darkens with great rapidity up to a certain point, when the resulting photograph attains a sharpness and per- Royal Society. 227 fection of detail which nothing can surpass. To this process the author applies the name of Chrysotype*, to recall to mind its analogy with the Calotype process of Mr. Talbot, to which in its general effect it affords so close a parallel \. 2. "Experimental Researches on the Elliptic Polarization of Light." By the Rev. Baden Powell, M.A., F.R.S., Savilian Pro- fessor of Geometry in the University of Oxford. This paper contains an experimental'investigation of the pheno- mena of elliptic polarization resulting from the reflexion of polarized light from metallic surfaces, and the theory on which they are ex- plicable ; the analytical results being given in a tabular form, and applied to the cases of the experiments themselves. 3. " On the Influence of the Moon on the Atmospheric Pressure, as deduced from the Observations of the Barometer made at the Magnetic Observatory at St. Helena." By Lieutenant J. H. Le- froy, R.A., late Director of that Observatory. Communicated by Lieut.-Col. Sabine, R.A., F.R.S. In order to determine the dependence of the barometric pressure on lunar influence, the author arranges all the two-hourly observa- tions in each lunar month with relation to the time of the moon's passing the meridian; entering in one column the observation of each day nearest to the meridian passage, whether before or after ; and en- tering in separate columns those corresponding to two hours, four hours, six hours, &c, before and also after that observation. The monthly means at every two hours from the meridian passage are then taken ; and again, the means at the same intervals, for each three months from September 1840 to December 1841. From the results thus obtained the author states that it appears that the moon's passage over both the inferior and superior meridian produces a slight increase of pressure ; a maximum in the curve occurring at both (that of the latter being slightly the greater), while the minima correspond to the moon's rising or setting. It appears also, that the rise of the tides will not account for the whole amount of the increase of pressure, even admitting that it has a tendency to produce an effect of that nature. The times of max- ima do not correspond ; and there appears to be no atmospheric establishment. The pressure is greater about the period of new moon than at full moon ; and greater in the third and fourth than in the first and second quarters ; a result which agrees with that given by Mr. Howard for the climate of London. The observations of both years agree in making the pressure greater under the Peri- gee than under the Apogee. Mr. Howard had found that the mean pressure in Great Britain, which is in the opposite hemisphere from St. Helena, is greater under the Apogee than under the Perigee. 4. " Notices of the Aurora Australis from the 1st to the 31st of » Note by the Author. — A solution of silver produces a like effect, and with greater intensity, but much more slowly. Consequently the name Chrysotype would seem less appropriate than Siderotype. — J. F. W. H. [f Mr. Talbot's account of his Calotype process appeared in Phil. Mag., Third Series, vol. xix. p. 88, 164 — Edit.] Q2 228 Royal Irish Academy. March 1841, made on board H.M.S. Erebus; extracted from the log-book." By Captain James Clark Ross, R.N., F.R.S. 5. "An Appendix to a paper on the Nervous Ganglia of the Uterus, with a further Account of the Nervous Structures of that Organ." By Robert Lee, M.D., F.R.S. After premising a short history of the opinions of Galen, Dr. William Hunter, Mr. John Hunter, Professor Tiedemann, Professor Lobstein, and Professor Osiander, relative to the existence, course, and enlargement of the nerves of the uterus, the author adverts to his own researches on this subject, which commenced with his dis- covery, in April 1838, of the trunk of a large nerve accompanying the uterine vein, and of the great nervous plexus with which it was continuous. Of this discovery he gave an account to the Royal Society in a paper read on the 12th of December of the same year. In a subsequent paper, he described some large nervous ganglia* situated at the neck of the uterus ; and in the present appendix he describes other nervous structures of still greater size which pre- sented themselves to him, on a still more complete dissection which lie made of a gravid uterus at the full period of gestation. It ap- pears from the results of these dissections that the human uterus possesses a great and extensive system of nerves, which enlarge du- ring pregnancy, along with the coats, blood-vessels, and absorbents of that organ, and which after parturition resume their original con- dition. It is chiefly through the influence conveyed by these nerves that the uterus is rendered capable of performing its various func- tions, and by which sympathies are established between it and other parts of the system. 6. " Magnetic-term Observations of the Declination, Inclination and Total Intensity, made at the Magnetic Observatory at Prague, for February, March, and April 1842." By C. Kreil, Director of the Prague Observatory. Communicated by S. Hunter Christie, Esq-, M.A., Sec. R.S. 7. " Magnetic and Meteorological Observations for February •1842, taken at the Magnetic Observatory at Madras." Presented by the Honourable Court of Directors of the East India Company. Communicated by the Council of the Royal Society. 8. "Magnetic and Meteorological Observations from May 1841 'to March 1842, made at the Observatory established by the Rajah • (6.) £ = e (p cos y sin

; . . . . (9.) u sine and for the second, . sini . sin w' , , , /in \ tanw' = — r, s' = , r" = s'v'. . . . (10.) u' sin i When i lies between i' and a certain smaller angle i", two of the roots will be real, and two imaginary. The real roots correspond to waves which follow the law of Fresnel ; the imaginary roots give a single wave, following the other laws just mentioned. Lastly, when i is less than i", all the roots are real, the refraction is entirely regulated by Fresnel's law, and the reflexion by the laws already discovered and published by the author. If the crystal be uniaxal, and all the values of z' imaginary, the ordinary wave normal will coincide with the axis of x' ; whilst the extraordinary wave normal and the axis of z' will be conjugate dia- meters of the ellipse in which the index-surface is cut by the plane of incidence. When a = b = c, the crystal becomes an ordinary medium ; there is then only single refraction, and the refracted wave is always per- pendicular to the axis of x' . With regard to the ellipse in which the vibrations are performed, it may be worth while to observe, that if it be projected perpendi- cularly on the plane of incidence, the projected diameters which are parallel to the surface of the crystal and to the wave plane will, in all cases, be conjugate to each other, and their respective lengths will be in the proportion of r to unity. The vibrations, it is obvious, are not performed in the plane of the wave, though they take place without changing the density of the aether. The new laws here announced are, properly speaking, laws of double refraction, and are necessary to complete our knowledge of that subject. Between them and the laws of Fresnel a curious ana- logy exists, founded on the change of real into imaginary constants. The laws of the total reflexion, which accompanies the new kind of refraction, need not to be dwelt upon in this abstract, as nothing is now more easy than to form the equations which contain them. In fact, the difficulties which formerly surrounded the problem of re- flexion, even in the simplest cases, have completely disappeared, since the author made known the conditions which must be fulfilled at the separating surface of two media. In what precedes, it has been supposed that the reflexion and re- fraction take place at the first surface of the crystal, because this is the more difficult and complicated of the two cases into which the question resolves itself. But it will usually happen in practice that a ray which has entered the crystal will suffer total reflexion at the second surface, while the new kind of vibration is propagated into the air without. The refracted wave will then be always perpendi- cular to the axis of x{ ; the fcwo reflected rays, within the crystal, Intelligence and Miscellaneous Articles. 233 will be plane-polarized, according to the common law, but they will each undergo a change of phase ; and the vis viva of the two rays together will be equal to that of the incident ray, the vis viva being measured by the square of the amplitude multiplied by the propor- tional mass. In conclusion, the author states a mathematical hypothesis, by which both the laws of dispersion, and those of the elliptic polariza- tion of rock crystal, may be connected with the laws already deve- loped. XLI. Intelligence and Miscellaneous Articles. ON CURCUMINE. BY M. VOGEL, JUN. TO obtain the colouring principle of turmeric root, the author treated it, reduced to powder, repeatedly with boiling water, till it nearly ceased to be coloured by it. The dried residue, thus deprived by water of its mucilaginous, gummy, and a part of its extractive matter, was repeatedly boiled in portions of alcohol of specific gra- vity 0*8 ; this dissolved the greater part of the colouring matter, but it is not possible to extract it totally, for the turmeric powder al- ways remains coloured; the alcoholic solution is to be filtered when cold, and is of a deep brownish-red colour. A portion of the alco- hol is to be separated by distillation, and the residue is to be evapo- rated to dryness in a porcelain capsule. A brown viscid mass re- mains, which retains some brown extractive matter and traces of chloride of calcium, which is one of the salts that the root contains. To separate these two substances, M. Pelletier's plan was adopted ; this consists in treating the residue with boiling aether, which be- comes of a brownish-yellow colour. The extractive matter, which resists the action of the aether, is of a black colour, and attracts moisture from the air on account of the chloride of calcium which it contains. The decanted aether ought to be slowly evaporated, and after cooling, brownish-red fragments remain, which readily fuse, and may be poured into stone moulds or on glass plates. In this state the curcumine, when heated to redness on platina foil, does not leave the smallest residue of inorganic substances. Attempts were made to volatilize the oil which the odour of the curcumine evinced that it still retained, by repeatedly fusing it ; but as this method did not succeed perfectly, another was tried, which led to a more satisfactory result. The residue obtained by evaporating the aethereal solution was dissolved in alcohol, and on the addition of an alcoholic solution of acetate of lead, a red precipitate was immediately formed ; the salt of lead was added as long as precipitation occurred. When this precipitate is washed and dried, a reddish-yellow powder remains, which consists of the yellow colouring matter and oxide of lead, the proportion of the latter varying from 43-67 to 56-33 per cent. To separate the lead, the powder is to be diffused in water and treated with hydrosulphuric acid gas ; when the action of this is complete, 234- Intelligence and Miscellaneous Articles, the powder, which has become of a deep brown colour, is to be washed and dried and treated with boiling aether, which dissolves the curcumine and leaves the sulphuret of lead. By evaporating the aether slowly, the curcumine is deposited in thin laminae, which are transparent and inodorous ; when reduced to a fine powder, curcumine is of a beautiful yellow colour, which is more intense as the powder is finer ; in small laminae it is of cinnamon colour, but when held up to the light it is of a deep red colour. By the process above described, about half an ounce of curcumine was obtained from a pound of the root ; attempts were made, but in vain, to sublime and crystallize it. At 104° Fahr. it fuses, and even at common temperatures the fine powder agglutinates; it burns with a bright flame accompanied with much soot ; by exposure to the sun's rays it soon loses its intense colour, and becomes gradually of a yellowish- white ; as curcumine is insoluble in water, but very soluble in alcohol and in aether, it appears to resemble the resins. M. Chevreul had already stated that curcumine is composed of oxy- gen, carbon and hydrogen, and M. Vogel proved that it contained no azote, by fusing it in a tube with six times its weight of hydrate of potash, no trace of ammonia being obtained. The mean of four combustions of curcumine, prepared as above described, yielded Carbon .... 69'501 Hydrogen . . 7*460 Oxygen 23039— 100' Journal de Pharm. et de Chim., Juillet 1842. ON THE ACTION OF ACIDS ON CURCUMINE. BY M. VOGEL, JUN. Dilute acids do not dissolve curcumine, but the concentrated do. When concentrated sulphuric acid is poured upon powdered curcu- mine it is dissolved, and a crimson solution is obtained ; the red colour immediately disappears on the addition of water, and green- ish-yellow fiocculi are deposited, which appear to be pure curcumine ; and hydrochloric and phosphoric acids act in a similar manner, but concentrated acetic acid dissolves it without effecting any change in its colour. The action of nitric acid differs from the above. One part of curcumine was mixed, in a porcelain capsule, with two parts of concentrated nitric acid, previously diluted with an equal volume of water ; at common temperatures no change appeared to take place, but when heated in a sand-bath rapid action occurred, the liquid rose in bubbles, so that it was requisite to remove the vessel from the fire till the violence of the action ceased ; after this the mixture was gently heated till it ceased to evolve any gas ; by this action the curcumine is separated into a resinous mass, which is de- posited in yellow fragments, and a yellow substance, soluble in wa- ter. The resinous substance, when repeatedly washed with hot water, and afterwards dried, may be easily reduced to a fine powder, which is yellow, and differs much from curcumine on account of its Intelligence and Miscellaneous Articles. 235 peculiar odour and elementary composition. The yellow substance, soluble in water, crystallizes from a concentrated solution in trans- parent needles ; the quantity formed is however so small, and it deliquesces so readily in the air, that its chemical constitution has not been hitherto sufficiently examined. The above -related experiments on the action of acids on curcu- mine readily explain how turmeric paper becomes of a brown colour by the action of concentrated acids, as well as by that of alkalies. The concentrated acids dissolve the curcumine and form a brown solution with it. — Ibid. [There is, however, this difference between the action of con- centrated acids and that of alkaline solutions upon turmeric paper : water immediately removes the colour occasioned by the former, but not that produced by the latter. — Edit.] ACTION OF ALKALINE SUBSTANCES ON CURCUMINE. Curcumine forms compounds with the alkalies, which are very so- luble in water. When powdered curcumine is treated with caustic potash, a brown mass results which is very soluble in water. The curcumine is completely precipitated from this alkaline solution by diluted acids. Dilute sulphuric acid occasioned a precipitate in the alkaline solution, which, when sufficiently washed, had the proper- ties of pure curcumine. According to the observations of M. Kartner, it is not the alkalies and alkaline earths only which change the yellow colour of cur- cumine to brown, but the salts of lead, uranium, boracic acid and borates occasion the same change in a greater or less degree. The shades of brown produced on turmeric paper by the alkalies and alkaline earths do not materially differ from each othef ; they depend on the concentration of the alkaline solutions employed. All weak acids restore the original yellow colour of turmeric paper browned by the alkalies : this happens simply because the acid com- bines with the alkali, and thus decomposes the brown compound of the alkali and curcumine. Turmeric paper, browned by a salt of lead, has its colour very readily restored by dilute acids ; but when altered by the salts of uranium the colour is almost black, and the yellow colour is not restored until the paper has been immersed in tolerably concentrated acid for nearly a quarter of an hour. A solution of boracic acid in alcohol alters turmeric paper to an intense orange colour, which is not removed by the action of any other acid ; but when touched with ammonia, it assumes for a short time a fine blue colour, which soon disappears by the volatilization of the ammonia. This blue tint is also more or less shown by im- mersing paper browned by boracic acid in solutions of alkaline sub- stances. A solution of borax renders turmeric paper blackish-gray ; the neutral borates of potash or ammonia impart to it a less intense gray colour. — Ibid. 236 Intelligence and Miscellaneous Articles. INSOLUBLE SALTS OF THE ALKALINE EARTHS DISSOLVED BY HYDROCHLORATE OF AMMONIA AND CHLORIDE OF SODIUM. M. H. Wackenroder states that sulphate of barytes is quite inso- luble, but that the sulphates of lime and strontia are soluble in so- lution of chloride of sodium ; the latter, though fslowly, yet com- pletely, and it is entirely precipitable from solution by dilute sulphuric acid. Sulphate of lime dissolves very readily in solution of chloride of sodium, and cannot be precipitated by dilute sulphuric acid. — Ibid. PRODUCTION OF FORMIC ACID IN OIL OF TURPENTINE. The acid reaction of the oil of turpentine of commerce is derived from formic acid, the presence of which is readily detected in the water employed in its rectification. According to M. Weppen, the formation of this acid can be ex- plained only by the oxidation of the oil by contact with the air. The action may be very simple : 1 atom of oil of turpentine .... =5C8H + 10O = 2 formic acid =4C4H+ 60 1 .... carbonic acid = 1 C 20 2 water = 4 H + 20 It appeared to M. Weppen a subject of interest to inquire if these changes really occurred, or whether other products were not also formed during oxidation. As oil of turpentine oxidizes slowly by exposure to the air, he endeavoured to effect it by distillation with chromate of lead and dilute, sulphuric acid. Soon after ebullition had commenced, the chromate of lead was reduced, and acidulous water distilled with the oil of turpentine, in which the presence of formic acid was discoverable ; there was evolved, at the same time, carbonic acid sufficient to ren- der lime-water very turbid. A question however arises, whether this carbonic acid is really derived from the oxidation of the oil of turpentine, or is a secondary product of the formic acid. — Ibid. PRECIPITATION OF CERTAIN SALTS BY EXCESS OF ACIDS. BY M. WACKENRODER. It is an important circumstance in analysis, that certain salts, especially sulphates and oxalates, are precipitated by an excess of acid, if they are dissolved in other acids, and especially in nitric or hydrochloric acid. If, for example, protosulphate of mercury be dissolved in diluted nitric acid, this salt may be almost perfectly separated by the addition of dilute sulphuric acid. Nitric acid, though with difficulty, dissolves sulphate of lead completely ; but if dilute sulphuric acid be added to the solution, the sulphate of lead is precipitated. If a great excess of nitric acid or hydrochloric acid holding lead in solution have not the excess got rid of either by saturation or hitelligerice and Miscellaneous Articles. 237 evaporation, a small quantity of oxide of lead may escape conversion into sulphuret by hydrosulphuric acid ; and th^ circumstance may lead to considerable errors. If sulphuret of ammonium be added to a dilute solution of lead, sulphuret of lead is formed, which completely and readily redissolves in moderately strong nitric acid and in hydrochloric acid : a current of hydrosulphuric acid gas may be passed for a long time in these solutions, especially in that of hydrochloric acid, without any effect; but when the solution is diluted with water black sulphuret of lead is precipitated, and after the addition of a sufficient quantity of wa- ter the precipitation is complete. If oxalic acid be added to a solution of chloride of strontium acidu- lated with a sufficient quantity of hydrochloric acid, it does not be- come turbid ; but this effect is produced by the audition of a small portion of lime. — Ibid. SOLUBILITY OF SALTS IN PERNITRATE OF MERCURY. M. Wackenroder finds that the chloride, bromide, iodide, cyanide, and sulpho-cyanide of silver are soluble in pernitrate of mercury, and that the ferrocyanide, sulphuret, and seleniuret of silver are in- soluble in the mercurial salt. These solutions are of a peculiar and uncommon nature. For example, neither nitric acid nor nitrate of silver precipitates anything from the solution of cyanide of silver in pernitrate of mercury ; but a sufficient quantity of hydrocyanic or hydrochloric acid, or metallic chlorides, precipitate from it cyanide or chloride of silver. On the contrary, hydrochloric acid, chloride of sodium or hydrochlorate of ammonia, readily precipitate chloride of silver from this solution ; an excess of nitrate of silver also pre- cipitates this salt completely, which nitric acid does not precipitate. The chloride, bromide and iodide of mercury also dissolve readily in pernitrate of mercury. Chloride of mercury can be separated from these solutions by a great excess only of chloride of sodium. — Ibid. ON LAUROSTEARINE. BY M. MARSSON. M. Bonastre found bay-berries to contain volatile oil, resin, gum, a fluid fatty matter and a solid fatty matter, which last he called stea- rine, and a peculiar crystallizable substance which he named laurine. As the characters assigned to this last substance resemble those of the stearoptens, its true nature appears to remain unascertained. By the recommendation of M. Liebig, the investigation was under- taken by M. Marsson, who discovered a fatty substance differing from those previously known, and which he has distinguished by the name of laurostearine. It was obtained by treating bay-berries re- duced to powder, three or four times with boiling alcohol, filtering it as quickly as possible, washing the substance deposited by cooling with cold alcohol, purifying it at first by fusion in a salt-water bath, and filtering while hot, in order to separate an uncrystallizable resinous matter, and afterwards by repeated crystallizations from alcohol. 238 Intelligence and Miscellaneous Articles. The properties of laurostearine are, that when purified by alcohol it is in the form of» small white brilliant silky light needles, which are frequently grouped in the form of stars. It is very difficultly soluble in cold alcohol, but readily soluble in strong boiling alcohol, and is deposited almost entirely in crystals as the solution cools. It is very soluble in aether, and by spontaneous evaporation' cry- stallizes, as it does from the alcoholic solution. It fuses at about 112° Fahr., and on cooling becomes amass resembling stearine, pre- senting no traces of a crystalline texture, and is brittle and friable. Solution of potash saponifies it pretty readily, and forms a perfectly bright soapy solution : the soap separated by chloride of sodium is hard, and yields by decomposition with acids a fatty acid, the lauro- stearic acid. By dry distillation it yields acroleine, and a solid fatty body, crystallizable from aether. It is formed of 1 atom laurostearic acid = C24 H46 O3 1 atom glycerine = C3 H4 O 1 atom laurostearine . . = C27 Hb0 O4 Ibid* ON LAUROSTEARIC ACID. BY M. MARSSON. This acid is obtained in the usual mode, by the addition of tartaric acid to a hot solution. Soda-soap prepared with pure laurostearine has the appearance of a colourless oil, which on cooling becomes a solid crystalline transparent mass ; it is very soluble in strong al- cohol, and still more so in aether, but it does not separate from either of these solvents in the form of crystals. Its fusing-point is lower than that of the laurostearine itself, being about 107° Fahr. The alcoholic solution has a strong acid reaction. The acid se- parated in the mode above described is a hydrate ; its formula is = C24 H48 O4, and that of the anhydrous acid, combined with bases in salts, is = C24 H46 O3. Laurostearic acid, therefore, con- tains, in the state of hydrate, an atom of water, which in salts is replaced by an equivalent of base. Bay-berries contain, besides, a considerable quantity of fluid green fatty matter and resin, but the last-mentioned does not possess any peculiar acid properties. — Ibid. ON THE PRESENCE OF ANTIMONY IN ARSENIOUS ACID. Mi A. Wiggers attempted some time since to preserve transpa- rent fragments of arsenious acid under hydrochloric acid. He did not succeed ; the arsenious acid became gradually cloudy and opake, but the examination of the hydrochloric acid proved that it con- tained a considerable quantity of oxide of antimony, Sb203. Seve- ral cases may occur in which it is advantageous to be aware of this admixture, and in this point of view the statement of the facts is not unimportant. A large portion of oxide of antimony sublimes with arsenious acid ; the hydrochloric acid completely * See p. 167 of the present Number. A New Metal — Meteorological Observations. 239 dissolves this impure arsenious acid, and yields a solution from which water throws down a white precipitate* sulphuretted hy- drogen an orange one of sulphuret of antimony, and then a yellow one of sulphuret of arsenic. Nitric acid, when heated, dissolves the mixture, leaving a residue of oxide of antimony containing arsenic acid, which is readily dissolved by hydrochloric acid and by tartaric acid; and it forms solutions with these acids, which possess all the reactions of oxide of antimony. M. Wiggers found oxide of anti- mony only in the vitreous arsenious acid from Andreasberg in the Hartz. — Ibid. DISCOVERY OF A NEW METAL. " In Part Seventh of my Journal, which you will receive next week, you will find a notice of the discovery of a new metal ; it has been named Didym ; it always accompanies Lanthanium, from which un- fortunately it has not yet been separated. All the researches on Lanthanium, as well as those on Cerium, are erroneous." — Extract of a letter from Prof. Poggendorff to W. Francis. METEOROLOGICAL OBSERVATIONS FOR JULY 1842. Cliiswick. — July 1 . Heavy rain : fine. 2, 3. Very fine. 4. Densely overcast. 5. Dry and windy : showery : clear and fine. 6. Very fine. 7. Overcast : rain. 8. Cloudy: heavy rain at night. 9 — 11. Fine. 12 — 14. Cloudy and fine. 15. Fine: dry haze. 16. Dry and clear. 17. Slight haze. 18. Sultry. 19. Slight rain. 20. Fine: showery. 21. Densely overcast. 22,23. Very fine. 24. Cloudless and hot. 25, 26. Very fine. 27. Slight rain in the morning : lightly overcast and fine. 28. Thunder-storm early in the morning, most violent between five and six a.m. : sultry : cloudy and fine. 29. Densely clouded : clear at night. 30. Cloudy : fine. 31. Cloudy and fine : clear at night. Boston. — July 1. Rain : rain early a.m. 2. Fine : stormy, with rain, thunder and lightning p.m. 3. Fine : rain r.M. 4. Cloudy. 5. Stormy. 6. Windy. 7. Fine. 8. Fine: rain p.m. 9 — 12. Fine. 13. Cloudy: three o'clock ther- mometer 76°. 14—16. Fine. 17. Cloudy. 18. Fine. 19. Cloudy. 20, 21. Cloudy : rain early a.m. 22. Cloudy : rain p.m. 23. Cloudy. 24. Fine : twelve o'clock thermometer 78°. 25. Cloudy. 26. Fine. 27. Fine: rain p.m. 28. Fine. 29. Cloudy: rain early a.m. 30. Windy. 31. Cloudy. Sandwick Manse, Orkney.— July 1, 2. Cloudy. 3. Cloudy: clear. 4. Cloudy : rain. 5. Cloudy : showers. 6. Cloudy. 7. Clear: cloudy. 8. Rain: fine. 9. Bright: drops. 10. Bright. 11. Cloudy : rain. 12. Bright and warm. 13. Damp: showers. 14. Showers. 15. Cloudy : drizzle. 16. Clear. 17. Clear: cloudy. 18. Bright: cloudy. 19. Clear: cloudy. 20. Clear: fog. 21—23. Cloudy. 24. Cloudy : damp. 25. Cloudy. 26, 27. Bright. 28. Showers. 29. Cloudy. SO, 31. Cloudy: damp. Applegarlh Manse, Dumfries-shire. — July 1. Showers. 2. Wet nearly all day. 3,4. Showery. 5. Rain and wind. 6. Fair and fine. 7 — 11. Heavy showers. 12. Fair and fine. 13. Showery. 14. Fair and fine. 15. Very fine. 16. Very fine: thunder. 17. Very fine, but cloudy. 18. Showers. 19 — 21. Fair and fine. 22 — 24. Very fine. 25. Very fine : sultry. 26. Very fine : cloudy. 27. Cool and cloudy. 28. Cool but fine. 29. Cloudy and threatening. SO, 31. Very fine. Sun shone out 30 days. Rain fell 12 days. Thunder 1. 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O CN -i O) O p^ 7* p> p -^ C)ClO 0)000 Ol Oi Ol O* O) O OOOCiOlOiOiOlO OO OlOOCOlOO CNCNCOCNCNCOCOCNCNNCNCNCOCOCrsCOCNCNCNCNNCOCOCOCNCOm to s o CO •q^uow o» t»> d josX "(I 2^ • « (NMMCNCTWMCNCMCNCOCO o ^ THE LONDON, EDINBURGH and DUBLIN PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. [THIRD SERIES.] OCTOBER 1842. XLII. Contributions to the Minute Anatomy of Animals. By George Gulliver, F.R.S., fyc. fyc. — No. IV.* On the Structure of Fibrinous Exudations or False Membranes. \ S mentioned in the last Number of the Philosophical **• Magazine, p. 171, in false membranes, resulting from inflammation, the structure is frequently identical with that of fibrine which has coagulated within or out of the body simply from rest. In friable exudations, as I have noticed in Ger- ber's Anatomy, p. 29-30, fig. 234, the corpuscles approach pretty nearly in number and appearance to those of pus, ex- cept that the former are commonly more loosein texture than the 4atter. In these exudations too the fibrils are now and then not visible, though they may often be seen clearly enough, and the minute molecules are generally very abundant, yet occasionally scanty, and sometimes altogether absent, or at least not recognizable- The figures in Gerber's Anatomy (244-251) are tolerably good representations of the fibrils and corpuscles which may be commonly seen in clots of fibrine. The fault of some of those drawings is that the fibrils are depicted too forcibly, and without that softness which they present when viewed in a clear transmitted light. Indeed, these fibrils often form a network so extremely delicate that it must be a matter of some difficulty to get it struck off satisfactorily, even if the drawings are made with accuracy ; and the same remark is applicable to the more straight and parallel arrangement which these fibrils often assume. The structure of false membranes will now be illustrated * Communicated by the Author, August 26, 1842. No. III. will be found in our last Number, p. 168. Phil. Mag. S. 3. Vol. 21. No. 138. Oct. 1842. R 242 Mr. Gulliver's Contributions to the by examples. All the figures are magnified about 800 dia- meters. Case 1. — A soldier, aged 22, 72nd Regiment, was admitted into hospital with pulmonary consumption, on the 25th of January, and died February 4th, 1842. Thirty-six hours pre- vious to death he had pneuma- thorax, the .air having escaped through an opening leading from a superficial vomica to the cavity of the pleura. The lungs contained several vomicae filled with what is commonly called softened tubercle, and lined with the very common kind of friable and whitish false mem- brane. The surface of the pulmonary pleura at a distance from the opening was covered with a rather thin and tough false membrane, and on the pleura nearer to the opening was a more soft and friable exudation. Fig. 1. Fig. 2. Fig. 1. The structure of the toughish false membrane just mentioned, made up of fibrils similar to those in clots of fibrine either coagulated within or out of the body. At A'a portion of the free surface is shown, and at B a portion of the attached or pulmonary surface. Several very minute molecules per- vade the false membrane ; at B there is an obscure appear- ance of corpuscles among the fibrils, and with the aid of acetic acid these corpuscles were clearly exposed. Fig. 2. The softer exudation from the same pleura. In the upper part of the figure the corpuscles are held together by an amorphous clot; just below several of them are floating free in the serum, and at the bottom of the figure their nuclei are clearly exposed by acetic acid. There were no minute molecules either free or in the clot, though some of them were observed in and on a few of the corpuscles. Compare this with the friable exudation, fi g. 5, in which themolecules were remarkably abundant. Minute Anatomy of Animals. — No. IV. Fig. 3. Fig. 4. 243 Fig. 3. Structure of the friable false membrane lining a vomica of the same lung. In the upper part of the figure the corpuscles are connected by a clot which is pervaded by granu- lar matter. Lower down are several free corpuscles, a few of which are perhaps altered epithelial cells, together with smaller objects, some of which may be free nuclei or nucleoli. At the bottom of the figure the effect of acetic acid on the cor- puscles is shown ; it did not produce any ropiness or preci- pitate in the matter. The pulpy matter contained in the same vomica was composed of corpuscles like those in the figure, but with a larger proportion of granular matter. Case 2. — A man, aged 41, had an old dropsy of the belly, of which he died five days after tapping. The intestines were connected together by coagulated lymph, which in some places extended in the form of a thin whitish and semitrans- parent membrane from one convolution of the large intestine to another, being in parts very thin and pellucid, and thicker, more opake, and white at intervals. Fig. 4. Structure of the false membrane last mentioned. A, corpuscles and very minute molecules in a network of de- licate fibrils at the edge of a fragment of the exudation. B and C, from a transparent pellicle-like part ; at B the fibrils present a parallel arrangement, and some of them appear granulated ; but they are commonly smooth, semitransparent, and apparently cylindrical. C, some isolated molecules of extreme delicacy and minuteness; they were rather fainter than here shown. D D, from thicker parts of the exudation in which no distinct structure is apparent. All the objects represented in this figure were occasionally seen in different parts of the same fragment of the false membrane, and some- times even in one field of vision. Compare the fibrils and corpuscles with those which I have formerly depicted in a R 2 244 Mr., GuWiver's Contributions to the false membrane, (Gerber's Anat., fig. 272), and the parallel arrangement of the fibrils with the same appearance in fibrine obtained from blood out of the body (I. c. fig. 246). Case 3. — A child 18 days old died of inflammation of the peritoneum, on the surface of which was some friable coagu- lated lymph. Fig. 5. Fia. 6. Fig. 5. The exudation just mentioned. There are some corpuscles, and an abundance of minute molecules. One of the corpuscles appears to be made up of objects like the pri- mitive discs of Dr. Barry. Compare this friable exudation with that, fig. 2, in which the molecules were absent. Structure of Fibrinous Exudations in Birds. It would be interesting to examine the organic germs in the fibrine of animals with blood-discs differing widely from those of man ; and, as remarked by Dr. Carpenter in his valuable work on Human Physiology, p. 471, observations of this kind should be multiplied, in order to test the accuracy of Dr. Barry's views respecting the origin of the tissues and of pus-globules from the blood-discs. The fibrine obtained by washing from the blood of birds contains a multitude of particles, which are figured in the Philosophical Magazine for August 1842, like the nuclei of the blood- discs. I had recently an opportunity of examining some large amber-coloured and nearly transparent clots of fibrine from the peritoneum of a silver pheasant. Fig. 6. A, corpuscles in the exudation from the bird just mentioned. The connecting fibrine is very minutely granu- lated, and the granules are so arranged in some parts as to present a very faint appearance of fibrils; but some of these seemed to be quite smooth, and they are somewhat too di- stinctly represented in the engraving. B, filaments about 7(y^*' /K ' •** /' t^-r— — ^-\n>/ T^-—Lih-- V^m/ /^\ :X''7 ^*~-<^ * From the dnnafes drs Mines, vol. xvii. M. Dufrenoy's Description of Greenovite. 247 to be silicate of manganese, and is placed as such in several collections in Paris. Greenovite occurs in crystals and in small amorphous cry- stalline masses ; it is of a deep rose colour, and its specific gravity is 3*44. Its hardness is greater than that of fluor spar or phosphate of lime, but it does not scratch glass ; the crystals are splendent, especially the faces M and T ; the ter- minal faces are often dull and tarnished. The primary form of the crystal is represented by fig. 1, but other faces have been observed, as shown in fig. 2. The measured and partly calculated angles areas follows: — P on M = 87° 10' s on T = 83° 56' P ... T = 85 50 s ... P = 153 25 M ... T = 110 35 s' ... T = 106 30 x ... M = 119 20 s' ... x — 146 20 x ... T = 118 10 n ... T = 110 13 x ... P m 140 6 56" n ... P = 155 37 s ... M = 107 50 n' ... P = 112 V This mineral is not acted upon by acids, and is not fusible perse by the blow-pipe ; microcosmic salt denotes the presence of titanium, and with soda it shows manganese. To analyse this mineral, M. Cacarrie fused it with five times its weight of bisulphate of potash ; the residue when cold dissolved slowly in water, but almost entirely ; the very small quantity which remained undissolved contained traces of silica, evidently derived from quartz mixed with the green- ovite; the rest was titanic acid. The solution was treated with hydrosulphuric acid, and then supersaturated with am- monia to separate the lime. The residue, composed of tita- nic acid and sulphuret of manganese, was digested in sul- phurous acid, which dissolved the sulphuret. The titanic acid unacted upon was collected, and there was also obtained by ebullition a trace of it from the solution of manganese; an accident prevented the quantity of lime from being determined, but it could not have amounted to one per cent. The pro- portions of the other constituents were ascertained by M. Ca- carrie to be Titanic acid 745 Oxide of manganese... 24*8 Lime • 99'3 [The crystal of this substance appears, from the author's statement, to be a doubly oblique prism, but from the sym- metrical "nature of the faces, and the near approximation of the angles, it may possibly turn out to be an oblique rhombic prism. We have not however seen this mineral. — Edit. Phil. Mag.] [ 248 j XLIV. New Definition of the Voltaic Circuity with Formula? for ascertaining its Power under different circumstances. By Alfred Smee, F.R.S.* Theory of the Voltaic Circuit. IN conducting my experiments on the reduction of alloys, certain phaenomena and peculiarities were noticed that have so important a bearing on the theory, or rather the rationale of the voltaic current, that it becomes my duty at once to draw up the curtain and expose the conclusions to which they lead, as a knowledge of them will give to the operator great advantages, and enable him, by rightly un- derstanding the force with which he is working, to conduct his various processes to the best possible advantage. In these experiments I noticed that in various mixed solu- tions the quantity of voltaic force passing was not at all de- pendent on the nature of the negative element, but upon the ease with which the hydrogen was removed from it. Thus in a solution of sulphate of zinc very slightly acidulated the hy- drogen could not be evolved from smooth copper, but would rather reduce the sulphate of zinc when connected with a small battery. The substitution of smooth platinum in no way added to the power, but the employment of platinized platinum caused an abundant evolution of gas, even to the re- moval of the zinc already reduced on the smooth platinum. Any metal having but little affinity for hydrogen caused a si- milar result; thus, iron caused gas to be evolved and increased the force passing, when smooth platinum would not have the effect, and even zinc itself caused a little gas to be evolved, because the adhesion of the gas to it is slighter than the ad- hesion to smooth platinum. In the same way I observed that nitric acid allowed far more electricity to pass than sulphate of copper; and that again, than dilute sulphuric acid, simply from the facility with which hydrogen reduces these substances being greater than the facility of its evolution. I moreover noticed in other cases that the hydrogen would rather be evolved than re- duce a metallic salt, — as sulphate of zinc ; — and in every case that the facility of its removal affected the amount of power passing, quite independently of the nature of the negative plate. Now these facts appeared to me a positive proof of there being no such thing as a negative plate contributing to the * Reprinted, with additions and corrections by the author, from a pam- phlet extracted, for private circulation, from his "Elements of Electro-me- tallurgy." Mr. Smee's New Definition of the Voltaic Circuit. 249 production of power, and that this latter is of no value, further than as a means for the removal of the second element of the intervening compound fluid. On the other hand, the mul- titude of experiments by Faraday all show that the chemical action between one element of a compound fluid and some conducting body appears to be the source of the power, or rather that the power is always directly proportionate to this chemical action. Putting these two series of facts together, an idea presented itself to my mind explanatory of the nature of the voltaic force, for if the force from the experiments of Faraday is proved to depend on chemical action, and the negative pole from my own experiments is proved to be useless, except as affording the means for the re- moval of the second element of the compound fluid, then it follows as a natural consequence, that if the chemical affinity of any substance for one element of a compound fluid is greater than the resistance offered to the evolution of the second, force is produced. Now it immediately occurred to me that some metals might be made to reduce from a solution of one of their own salts, metal of the same description, by placing the metal partly in a solution for one element of which it has great affinity and in which it is easily dissolved, and partly in a solution of one of its salts. This was actually found to take place in various cases, by following the facts that were made out respecting the ease with which hydrogen reduces various salts. ■ Zinc reduces zinc by taking a piece of the metal and doubling it, one half is then to be amalgamated and placed in dilute muriatic acid, and the unamalgamated into a strong solu- tion of chloride of zinc, made as neutral as possible, when the affinity of the zinc for the oxygen and the quick removal of the oxide by miiriatic acid is sufficiently great to cause zinc to be reduced at the other end of the same piece of metal. The use of platinum, palladium, silver, copper, or any other metal appears not to increase the action in the least, which experiment shows most powerfully the utter fallacy of the con- tact theory, or in other words, that the voltaic force is in any degree dependent on the opposition of one substance to another. In this experiment, according to the advocates of this now untenable doctrine, the force should have set from the amal- gamated zinc to the mercury, the two metals, according to those electricians, having from simply looking at each other the property of evolving power, — but we find that the che- mical affinity determined the course of the current. Copper may by very simple means be made to reduce cop- per with truly great rapidity ; for if a test tube be half filled with sulphate of copper, and then muriatic acid be poured 250 Mr. Smee's New Dejinition of the Voltaic Circuit, gently at the top, so that the two fluids do not mix to any great extent, and a copper wire be then placed throughout the whole length of the tube, it will speedily show signs of action. The copper in the acid will rapidly dissolve, whilst copper will be as freely deposited at the lower part of the vessel. Now copper will undergo no action alone, either in muriatic acid or sulphate of copper. This experiment may be varied by the use of different acids or even some salts at the upper part of the vessel, for although muriatic acid shows this experiment most strongly, dilute sulphuric acid or mu- riate of ammonia will produce the same result. Silver reduces silver by placing one end of a silver wire in a porous tube containing nitrate of silver, the other in dilute sulphuric acid, though the metal placed in either separately is not affected. Lead reduces lead by immersing one end of a piece of lead in a solution of the tris-nitrate of lead, the other in dilute nitric acid. Tin reduces tin by placing one portion of a piece of metal in muriate of tin, the other in muriatic acid. Gold even reduces gold by immersing one end of a gold wire in the chloride, the other in dilute muriatic acid, the two solutions being separated as in all the former cases by a po- rous diaphragm. There is a beautiful experiment detailed by Mr. Grove, which is analogous to those last described, though he attri- buted the results to a different cause*. His experiment is to place two pieces of gold wire in muriatic and nitric acid, sepa- rated by a porous diaphragm, when no action will take place on either, but on being connected, that in muriatic acid will rapidly be dissolved, and the nitric acid will at the same time be decomposed by the hydrogen transferred to the other part of the wire. From the various experiments which I have examined, added to the extensive researches of Faraday on the chemical portion of the voltaic pile, the voltaic phaenomena may be de- fined to be certain effects produced by the chemical action of a body on one element of a compound, and manifested be- tween this point of action and the evolution of the second element. The voltaic phaenomena might in other words also be defined to be peculiar properties evinced between the che- mical action of a body on one element of a compound, and the evolution of the second element, the point of abstraction and subsequent combination of the first element being called the positive pole j the point of evolution or removal of the second element of the compound body, the negative pole. [* See Phi!. Mag., Third Series, vol. xiv. p. 388.— Edit.] with Formula: for ascertaining its power. 25 1 Hence it might be called circular chemical action, because the phenomenon always evinces itself as a circle. These definitions suit equally every possible case, and there is but one point included in those definitions which is uncer- tain, though as they now stand, whichever way that doubtful case be taken, they equally apply. The difficulty, and the only one, that I know concerning the production of the voltaic force, is an uncertainty whether the force is produced by the analysis of the compound body, or the synthesis of the newly- formed salt. This is a point concerning which, perhaps, we shall ever be ignorant, yet analogy would rather lead us to suppose that the combination rather than the analysis is the source of the voltaic force. These definitions show why we cannot obtain the force from the union of two elements ; in- deed, we can never hope to obtain voltaic power from ordinary combustion; for though the energy of the combination of oxy- gen with carbon is immense, there is no second element, and therefore no intermediate point at which the effects can be manifested. For the same reason no force can be obtained from the union of liquid sulphur or bromine with metals. The intensity of chemical action being always proportionate to the voltaic power, and being the only source of power in the pile, it follows that (I) the intensity or the power the vol- taic fluid possesses of overcoming obstacles is equal to (F), the affinity which regulates the chemical action. But as we find that this power is lessened under different circumstances, I = F — O ; O standing for the whole of the obstacles af- forded to its passage. Let us take at once a circle and examine its properties. We find that the intensity of the action (I) is equal to the affinity (F) of the body used to separate one element of the com- Fig. 1 . pound fluid (in the galvanic bat- tery this is produced by the zinc and oxygen) lessened by the me- chanical resistances afforded by the removal of the newly-formed compound (a) by the obstruction offered to the passage of the force by the compound solution (r),by the imperfection of the conducting power of the solid parts of the circuit (c), and lastly, by the obstacle which is afforded to the removal of the second element of the compound fluid (e) ; thus we have al- gebraically I = F — a + c + r + e. This circle is supposed to consist of but a single atom of fluid, exposed at one time to the action of the body combining with one of its elements, 252 Mr. Smee's New Definition of the Voltaic Circuit, and all the resistances are supposed to be constant. In some cases we might be desirous of ascertaining the values of the other parts of the circle ; thus if we desired to find the affinity (F) F = I + a + c + r + e, — the conducting power of the con- necting part of the arrangement (c)c= F — l + a + r + e. The removal of the newly found compound (a) a=F — L+c + r + e, the resistance offered by the compound fluid (r) r = F — l + a+c + e, the resistance to the removal of the second element of the compound e = F— I + a + c + r. Sometimes this circle is exceedingly small, the (r) consist- ing of but one atom of the compound, and (c) but of a single atom of the body combining with one element. This might be properly called an atomic circle, a good specimen of which has heretofore been called local action. We must now consider the different parts of the circle in detail ; and now a question naturally arises whether the inter- vening compound may consist of any number of elements, or whether it is essential that the compound should be made up of only two elements. From a consideration of the voluminous experiments of our great authority Faraday, it would appear probable that the second hypothesis is correct, although it is just possible that if the body consists of more than two ele- ments, that the impediment to the evolution of the other ele- ments (e) or the resistance of the fluid part (r) become so enor- mously increased as to stop any (F) or series of (F) that we have ever applied. Another question also arises, as to whether compound must necessarily be a fluid which requires the same consideration as the first question. (F) the chemical affinity of a body for one element of a com- pound is immensely strong where zinc is employed, the at- traction of that metal for oxygen being most powerful ; but if we substitute iron, tin, lead, copper, or gold, for the zinc, the attraction being feeble, the value of (F) would be reduced in various proportions, in some cases almost to zero. (a) the removal of the newly-formed compound affords but little resistance when the new salt is soluble in the fluid and a sufficiency is supplied for that purpose. In batteries gene- rally the removal of sulphate of zinc affords but little obstacle, being quickly dissolved by water ; (a) in some cases is the removal of the first element of the compound by evolution, thus in the voltameter oxygen is evolved. In these cases (a) is very large, and offers great obstacles to the passage of the cur- rent. The removal of the first element is sometimes accom- plished by decomposition ; thus oxygen may be removed by hydriodic acid, by the decomposition of which body (a) is di- with Formula for ascertaining its power, 253 minished and the current of one battery will pass through it. The observations made with regard to the reduction of alloys in the case of e apply equally to (a), for the first element will al- ways be removed in the manner which affords least resistance. (r) varies very much from the extent of the interposed fluid, and its conducting power being very different in each case. It varies much in different batteries. Sometimes r is a very com- plex quantity, as when two or more solutions of different con- ducting power are used between the combination of one ele- ment of a compound and the evolution of the second. In Daniell's battery, for instance, it is made up of three parts, not only the resistance offered by dilute sulphuric acid and solution of sulphate of copper, but also a resistance offered by the interposed diaphragm. It might be made up of a far greater number of parts, for different parts may be of differ- ent temperatures, which alone (if the temperature interferes with the conducting power) would cause r to be complex. (r) becomes enormously increased when the force is compelled to travel round a corner. (c) the resistance of the connecting part of the arrange- ment is generally in batteries very slight, because we select metals which conduct pretty freely ; (c) may be very complex by being made of a variety of conducting substances; thus, if the connexions are made of wires of different kinds of metal, a different resistance is offered by each, (c) in every battery, is generally made up of three parts, the conducting power of the positive and negative plates, and the intervening connect- ing wires. (e) the resistance to the removal of the second element *, is generally very great, affording a considerable obstacle in all cases, but the differences in this respect are very remarkable. Ordinarily (e) is a simple quantity, but becomes complex when the hydrogen is removed in a variety of ways at the same mo- ment. It becomes a curious question to ascertain whether (e) might ever be made a plus quantity. If the force pro- ceeds from analyis, then the use of any body having great affinity for the second element might cause the current to be increased. If from synthesis, and this is most probable, if not absolutely certain, (e) can never be a plus quantity, but always a minus. In the removal of the second element by decomposition of another compound body, it is by no means uncommon for a voltaic circuit to be formed. In Grove's * The term second here may require explanation, for it is only used in contradistinction to the term first, which is applied to that element which by combination forms F. Either element of a compound may be first or second, according as it may happen to assist in the propagation of the force. 254 Mr 4 Smee's Nexv Definition of the Voltaic Circuit, battery the hydrogen acts upon nitric acid, forming water, and setting deutoxide of nitrogen, &c. free ; but in this case the intermediate part between the combination of the first element and the removal of the second, is only the atom of hydrogen ; it therefore follows that this action must be re- garded as nothing but a series of little local batteries, or atomic circles, having nothing to do with the great battery which we make available for our purposes. It is absolutely essential, according to our definition of the voltaic force, that to be enabled to apply this principle for any purpose, however small a quantity of the force may be re- quired, that either (c) or (r) should possess a capability of being so far prolonged as to enable us, with the imperfect powers that nature has furnished us, to handle or deal with these intervening portions of the circuit. In the principal batteries now in use, their relative powers and attributes may be fully understood by considering each of the above properties in their construction. F. a. c. r. e. Grove large small small medium little. Daniell large small small most much. Smee large small small small much. Smooth platinum large small small small enormous. Thus the four batteries may be considered equal in the properties of the F, a, c, the differences being only in (r) and (e). In Grove's the (e) is so small as not only to compensate a slight increase in the (r) over mine, as usually constructed, but to give a great advantage to his form of battery. In DanielFs the (e) is perhaps rather smaller than in mine, but that is more than counterbalanced by (r) being larger in Daniell's than in mine. The effect of these properties are, that F in Grove's is diminished but little, F in mine more, in Daniell's more still; and in the smooth platinum battery by far the most. Thus is explained the decomposition of dilute sulphuric acid between platinum plates, by one cell of Grove's battery, and the same result not being obtained by the others. This equation is not only valuable for batteries, but applies to every single case where any substance acts upon a compound fluid in such a way as first to decompose it, then to combine with one of its elements, and set free in some way the other. Thus, if potassium be cast into dilute muriatic acid, (F) is im- mensely large, potassium having a violent affinity for oxy- gen; («) is exceedingly small, potash being readily soluble in water; (r) is almost nothing, only one atom of fluid being traversed by the force; (c) is practically nothing from the with Formula: for ascertaining its poxver. 255 same cause; (e) is very small. The result of such a state of things necessarily causes a vast intensity of action, and an ex- plosion is the result. Good specimens of contrasts in the magnitude in the se- veral parts of the circuit are to be seen in the relative power of (F), as obtained by zinc and silver; in the relative resist- ance of (a) in the solubility of sulphate of lead and sulphate of zinc ; in the resistance of (r) in the conducting power of pure water and muriatic acid; of the resistance of (c) in a leaden wire a hundred miles long, and a short silver one; in the resistance of (e) in the evolution of hydrogen from smooth platinum, and its removal by nitric acid. The relative degrees of action evinced by zinc, tin, iron, and lead upon sulphate of copper are easily explained; (F) differs from being larger, (a) in being smaller when zinc is employed, whilst (c), (r), (e) in each case remain nearly the same ; (a) indeed is so large when lead is employed as soon to put a stop to the action. How intelligible is the want of action of dilute sulphuric acid on amalgamated zinc, if examined by our equation for (c) ! the adhesion of the second element, hydrogen, being increased enormously, counterbalances (F), the affinity of zinc for the first element, or oxygen, and no action takes place. Amalga- mated zinc is rapidly dissolved if placed in a solution of salts of copper or silver, for (e) in that case is depressed, the hy- drogen rapidly reducing the copper. Nitric acid in the same way does not respect the amalgamation of the zinc, for (e) in that case is also diminished by the removal of hydrogen from the decomposition of the acid. As the adhesion of hydrogen to plumbago is very great, it occurred to me that the simple application of black-lead to zinc would, by preventing the evolution of hydrogen, increase (e), and therefore stop the local action ; but although the experiment fully succeeded, the plumbago so quickly came off, that I have not at present made any practical application of the experiment. The above cases, with all their analogies, are not the only ones to which the equation applies, for it will account per- fectly for the action of bodies on each other. In cases of single elective affinity, as the action of sulphuric acid on nitrate of barytes, a compound is decomposed, one element enters into another combination, the other is set free ; a voltaic circuit is therefore produced, the parts of which are thus made: (c) Sulphuric acidl(F) o)/Bar>'tes . j (a) v ' \Nitric acid (e) In cases of double elective affinity, as the action of sulphate 256 M r. Smee's New Definition of the Voltaic Circuit, of ammonia on nitrate of barytes, a similar circuit is formed thus:— ^) (F) /"Sulphuric acid Ammonia ~\, .* (a) |_Barytes Nitric acidj v' In both these cases, however, we have not the means of in- creasing the (r) and (c) to a tangible size (at least I have never been able to do it), and at present these actions have been restricted to the formation of atomic circles. There are some cases where we can extend the intermediate parts (c) and (r), and then our definition of the voltaic force with the formula arising from it enables us to form most ex- traordinary voltaic circles, which indeed we never could have formed before, unless we happened to light upon them by chance : thus proto-sulphate of iron, placed on one side of a diaphragm, and nitrate of silver on the other, will give a cur- rent when connected with a platinum wire, and a beautiful deposit of silver will be reduced on the platinum wire, on the nitrate of silver side of the circuit. In the same manner circuits may be formed of proto-sul- phate of iron and chloride of gold — of proto-nitrate of mer- cury and chloride of gold — of oxalic acid and chloride of gold, &c. In all of which cases the metal is freely reduced on that part of the platinum wire inserted in the metallic salt. The reason why a galvanic circuit is formed in these cases is sufficiently obvious ; water is the electrolyte or compound decomposed, proto-sulphate of iron is the substance combining with one element, and the metallic salt affords a means for the removal of the second element or hydrogen, and as we have the power of extending the compound (r) and connecting parts (c), not only an atomic circuit, but a working battery may be made. At the diaphragm or the point of juncture of the two liquids, indeed, an atomic or local battery is formed independently of the general or working battery. A second local battery is formed at the point of decomposition of the metallic salt by the hydrogen. The following are the parts of the circuit in the above cases. ~ _) (F)f Proto-sulphate of iron Platinum wire f(a) \_Oxygen Hydrogen {e)f * The (e) in this case does not form a secondary voltaic circle, but is the union of two primitive elements. f (a) is the removal of the per-sulphate of iron by solution ; (e) is the removal of the hydrogen by the decomposition of the metallic salt. with Formula for ascertaining its power. 257 It would be extremely interesting to find every case of de- composition of a compound fluid obedient to the equation, and indeed there is every appearance of that being the fact. The impossibility of giving a negative tendency to a metal when hydrogen is removed from its surface is also perfectly accounted for by our equation ; for hydrogen, as has been al- ready shown, protects the metal ; so when a facility is offered for its removal, not only is the direct protection removed, but by diminishing the value of [e), (F) the natural affinity of the metal for one element of the fluid, having but little resistance opposed to it, begins to act, and the metal is therefore dissolved. The superior action of a rough metal in contrast with a smooth one, is explainable on the equation most satisfactorily, for in the first case the affinity (F) is but feebly opposed by the resistance to the evolution of the hydrogen (e)t whilst in the latter case (F) is so strongly opposed by (e) that no action can take place. Zinc shavings, which always have one side bright and the other rough, show this phenomenon clearly. Polished zinc or iron also show this effect in a striking manner. Hitherto we have considered (F, a, c,r,e) in every case to be constant, but in many instances they are subjected to con- tinual variation. I do not, indeed, happen to recollect an in- stance of (F) varying to any amount, but (a) varies frequently ; in the gradual saturation of a fluid it progressively increases, so much so, as at last to equal (F). This accounts for zinc ceasing to be dissolved on the saturation of the fluid by sul- phate of zinc, although still intensely acid, (c) generally re- mains constant, (r) is very unsteady, for as in all voltaic ar- rangements the fluid is always undergoing change, it is there- fore sure to be altered in its conducting power, (e) is sub- ject to great variations from alteration of the liquid and other causes. In every case of a single battery we have seen that the in- tensity is equal to chemical affinity, minus the resistances to that affinity. In a compound battery the expression is equally simple, for the intensity is equal to the sum of the affinities, minus the sum of the resistances. In a series of batteries all of the same nature, V = F-a+c+r + fx». Sometimes (») is very complex. For example, if a compound battery be made up of a Grove's, a DanielPs, and my own, the values of (I) must be considered separately, and their sum taken. The diagram exhibits well the arrangement and properties of the compound battery. A good example of the effect of (n) is seen in the water battery, where (I) is exceedingly small from the resistances Phil. Mag. S. 3. Vol. 21. No. 1 38. Oct. 1842. S 258 Mr. Smee's New Definition of the Voltaic Circuit, of (a) and (r) being large, but becomes amplified to such a Fig. 2. degree by («) as to possess prodigious force; indeed as it possesses a capability of being amplified infinitely by an infinite series completely insulated, a battery might be constructed powerful enough for the force to pass from one electrode, placed in the Thames at London Bridge, and the other in some river in Australia, though the resistances of (r) and (c) in this case, from their extreme length, would be very great. In every water battery, as (a) instead of being constant gradually increases, the power gradually declines at length to nothing. The curious and wonderfully-multiplying powers of (w), whereby the intensity can be increased, precludes our saying that the galvanic power is unable to effect any particular ob- ject; for, after all, it might turn out that (n) was not magni- fied sufficiently to attain that end. If we desire to find the number of batteries in any arrange- ment, it could be easily ascertained by the following equation : n = =. F — a + c + r + e When we are turning our power to some application it is very convenient to consider the purpose for which it is applied as a resistance, and call it R. If we have a series of them alike it would be R x m, m standing for the number composing the series. If, however, the series is not alike, it would be R + R' -f R". The intensity of the current after having passed this resistance would be also equal to the sum of the intensities, minus the sum of the resistances, l" = F— a+c-i-r + exn — R;«. The R is frequently very complex, as in the reduction of me- tals in a decomposition trough, where it is made up of as many parts as a voltaic battery. Having amply discussed the power of the force to overcome obstacles, we are led to determine the time in which any given number of equivalents of voltaic power can be obtained. Hitherto we have considered the circuit to be made up of a sin- gle atom of the body combining with one element of the com- pound, and if the affinity exceeds but ever such a trifle its with Formula: for ascertaining its power. 259 obstacles, then in time any amount of work would be per- formed provided the current remained constant. A current can easily be conceived so feeble as to take millions of years to reduce a pound of copper. If the entire circuit of single atoms be increased at every part, in fact if the mathematical voltaic circle be increased to the size of a tunnel, then (W), the amount of work performed in a given time, would be equal to the intensity of the battery, minus the resistance of our working apparatus, multiplied by the number of parts of the tunnel (A) thus: W=T^nr!.xA. This equation, however, gives us the total amount of che- mical actions in the whole series of batteries and decomposi- tion troughs, or, in other words, the sum of the actions evinced in each; we generally, however, are desirous of estimating the amount done in one particular cell, in which case we di- vide our equation by the number of cells and troughs (n) thus : n Sometimes this equation is rendered extremely complex by an increase of the circuit at one side but not at another ; in fact, the tunnel is cut away on one side, and this is a case that is perpetually occurring in practice. In this case it is not impossible but that the force is only derived from those parts of the circuit which are complete : in that case the equation T— R x A p * would be W" = " , p standing for the incomplete parts. In this view of the question we are supported by the analogy of water running through a pipe of given dimensions from a cistern ; for however large this cistern be, pro- vided there be no more pressure, the water running through the pipe would be the same. So far as the voltaic fluid is concerned I feel certain, from numerous observations, that beyond a certain point the increase of a battery does not cause a greater amount of electricity to pass through a given resistance ; and, perhaps, in those cases, where the enlargement of a battery in- creases the voltaic force, the battery in the former instance was deficient in size in relation to the size of the resisting part R, the tunnel, in fact, having been defective originally in that part. It is possible that the expression for this con- dition might be altered ; for R, the resistance to the single S2 260 Mr. Smee's New Definition of the Voltaic Circuit, voltaic circle, might possibly vary in some new manner, for which further experiments are wanted. In that case it would be I'A— 151 • "W" = ' the old English 1& standing for the new resistance afforded to the whole current. The tunnel might be cut away at any other part besides (R), thus it might be de- ficient at (F), (a), (c), (r), or (e) ; but the student will readily perceive the expressions for these cases. The algebraic formula for (W) is replete with interest, for it accurately defines the value of (W) in determining the so-called power of any battery. The power of a battery is the inten- sity multiplied by the quantity, in other words, I' x A ; but our equations show that W is not equal to I A but to I A — R A, and from that we deduce that I A = W + R A ; therefore it is impossible by Faraday's voltameter to ascertain the value of I' A at once, and it is necessary first to find the value of A. The immense mass of experiments in which the voltameter has been assumed to be equal to I' A, must now be discarded as inaccurate, and no deductions drawn from them ; but all future experimenters, by attending to these equations, may make the results obtained by the voltameter absolutely correct. The symbol (A) I have before noticed stands for the value of atoms of the compound fluid exposed to the action of a body removing one of its elements. It sometimes becomes an incon- stant quantity, as in the cases where non-conducting substances incase the poles of the battery. A is tolerably constant in Da- nielPs and in Grove's battery, most so in the former. It is less constant in mine, and very inconstant in most smooth metal batteries. A is analogous to what experimenters formerly very properly called the quantity of a battery. The contact theorists indeed would fain make us believe that there is no such thing as either quantity or intensity, but they have erroneously multi- plied intensity (I') with quantity (A), and called it electromotive power, and then denied the existence of the several parts of that power, which is nothing but the I' A of my equation with the (c) and (r) abstracted from the (I'), and considered separately. This is the point on which Ohm and his followers have perplexed all English philosophers ; still, notwithstanding this mystification, to Ohm is due the hearty thanks of every elec- trician for showing that voltaic force is diminished by resist- ances, and doubtless his doctrine of resistance is a most im- portant and lasting discovery. Ohm's equation, in the complex mannerin which he has given it, presents fewest difficulties when applied to solid connecting resistances ; thus those who used bat- teries with connected wires could appreciate it in many cases, but •with Formula for ascertaining its power. 26 1 thosewhowere engaged in experimentseither in the construction of the voltaic battery itself or in complex resistances, found it perfectly inapplicable. By the equation for (W) we find that W A = -p — p- which I have already mentioned must be deter- mined before we can 'find the value of I' A, or what is properly called the power of any battery. Sometimes W is very small, as in De Luc's columns, where the total amount of chemical action, although in) is frequently 500 to 1000, is so small, that experimenters have even denied its existence ; but when we consider that these very persons assert, that as soon as chemical action does become decidedly manifest, the action ceases, how strongly do they favour our views ! for, according to our equation, we expect (a) to be gradually increased till all action would be stopped. W, in- deed, according to our equation, might be so small, as not to be cognizable to our senses for weeks, months, years, or cen- turies ; and yet (I) multiplied by a very large (n) would show enormous intensity or power of overcoming resistances. The present modifications of the theory of galvanism are perfectly consonant with every practical direction given in the preceding pages, and the only difference in the theory will be found irt the uncertainty expressed upon the contact and chemical action theories. Indeed, in page 54< of my work, as already cited, the result is almost given in words though not in letters. By removing the slight difficulties which ap- peared to envelope the latter theory, by showing the necessity for a negative pole to cause power is unfounded, the beautiful doctrine of Faraday is placed on the surest foundation, and the extraordinary and dogmatical paradox of a power without a cause is proved to be a fanciful chimaera. With regard to the connexion of the voltaic power with that of electricity produced from other sources, perhaps it might be expected I should say a few words. In the voltaic battery (I) is small, but may be increased to any size by (n), and as we have the power of increasing (A) also unlimitedly, we can perform any amount of work per second, indeed we might throw down hundreds of tons of copper per second, if we were disposed to make our circuit large enough. In frictional electricity (I) is enormous, but (A) is depressed to its utmost limit, so that not having a perfect command over (A) to increase it indefinitely, we cannot at present obtain what work we please in a given time. In animal electricity (I) is great, (A) is moderately large. In thermo-electricity (I) is depressed, perhaps increasingly, so that although (A) and (n) may be multiplied indefinitely, yet, practically, we should never be able thoroughly to overcome the smallness of (I). In that 262 Mr. Smee's New Definition of the Voltaic Circuit. mighty operation of Nature which has just occurred, where the noise accompanying the discharge of the electricity over the metropolis was so awful as to alarm not only delicate females, but the stoutest hearts of men, and even the heretofore un- terrified nervous system of infants — in that terrific storm, when every living creature trembled, and Nature seemed al- most alarmed at her own operations, how vast was (I) ! how large (A) ! Could I therefore but have imprisoned that collection of force which in discharging itself committed such devastation on houses, churches, and trees, and, having en- cased it, been able to have let it loose as it might have been required; then indeed would all batteries have been henceforth discarded as playthings for children — philosophical toys to be admired, still despised, for (I A) being unlimitedly great, we could obtain what work we pleased in any given time, at no expense. The estimate of the parts of (I) in other cases where force is produced, i. e. an electricity not proved to be derived from chemical action, I do not deem it my business now to consider, but great difficulties would attend its accurate investigation, as it is almost impossible to magnify the size of the circle in these cases, in such a way as to make the action in each part cognizable by our senses. It is however quite evident, that as in the voltaic and thermo circuits (I) may be magnified to any extent by (n), that the power of (1) in every case might be brought to the same standard in the power overcoming the resistances R', R", R'", &c. The obstacles to the completion of the voltaic circuit (O), are made up as we have seen of several parts, a, e, r, c, but, although they differ in kind, still as they have similar resisting properties, a perfect table might be made, referring them to one given standard, showing the separate value of each. The principle on which it should be constructed, is the law of the completion of the voltaic current, detailed when treating of the reduction of alloys ; and as soon as we have this table accurately and numerically drawn up, the principles of the passage of the voltaic circuit, which formerly puzzled the most enlightened experimenters, will be rendered certain, and the difficulties will be also reduced to the facility and certainty of common arithmetic. Having obtained perfect tables of (O) and its several parts, we can readily obtain the relative value of (I), derived from various sources, by finding out what extent of (O) neutralizes each individual (I), and the value of (I), or the force of any battery, will be determined with equal facility. Complete tables of (O) and (I) now be- come the greatest desiderata, not only to electro-metallurgists, but to all who use the voltaic battery. Prof. Kelland on the Theory of Molecular Action, 263 I now bid adieu to my theory of galvanism and my formulae and to those who have neither time nor inclination to dive into these mysteries, I would say, — remember, in all operations that the sum of the resistances does not exceed the sum of the intensities ; and that in increasing the circuit, every part is equally enlarged : — to those who have devoted themselves to these properties — remember they will be useless if not brought into active operation ; thus, if any difficulty occurs in your voltaic circuit, refer it at once to its proper head, and the operator may be sure that a continual practice and habit of using these formulas will enable him to conduct his proceedings with a certainty never obtainable by blind experiment. In concluding these formulae, I herewith leave theory and rationale altogether, for having completed the principles, as far as I am capable, of everything relating to electro-metal- lurgy, I shall enter at once into the applications of the science for the direct purposes of the arts ; and although everything that will be contained in the subsequent parts of this work has already been .comprised in the parts already finished, yet there are many little practical difficulties to be surmounted — many little circumstances to be pointed out which the operator is likely to overlook or forget in conducting his operations, and these are the circumstances to which the concluding pages will more especially be devoted. Henceforth the work will be entirely practical, as heretofore it has been exclusively theoretical. There is a reproach attached to the very word, theory ; the sense in which it is employed means rather ratio- nale than theory, for whilst it has been my constant endea- vour to shun theories without facts, I have tried and tried hard to generalize all extensive series of facts, and to give the rationale of every circumstance which is likely to occur to the operator. XLV. Reply to some Objections against the Theory of Mo- lecular Action according to Newton's Law. By the Rev. P. Kelland, M.A., F.R.SS. L. $ E., F.C.F.S., $c, Professor of Mathematics in the University of Edinburgh, late Fellow and Tutor of Queen's College, Cambridge. [Continued from p. 208.] MR. EARNSHAWS first argument is, " Dispersion in a refracting medium cannot be accounted for on the finite- interval theory, unless there be also dispersion in vacuo. Now as there is no dispersion in vacuo, I infer generally, that the finite-interval theory cannot account for dispersion" (pres. vol. p. 47). The difficulty which is here brought forward is the same 264; Prof. Kelland's Reply to some Objections against the that has so often been started ; it in fact goes to the foundation of the Jinite-interval theory. If that theory be supposed to consist in the hypothesis, that the vibrations of the particles of aether within a medium are unaffected by the presence of the particles of matter in any shape, I shall not undertake to be its advocate. I will simply refer to M. Cauchy's Memoir (Prague), p. 188. But it is evident that Mr. Earnshaw admits into that theory the indirect action of the particles of matter ; for he says, " I have not taken account of the direct action of matter upon the aether ; but as my results are inde- pendent of arrangement, it is obvious that the indirect effect of matter is included in them. Consequently the indirect effect of matter never can assist us in accounting either for the transversality of vibrations or for dispersion" (p. 48). lam obliged to ask Mr. Earnshaw what he conceives to be the di- rect effect of matter. The phrase was, I think, originated by myself, and was meant to express the attractions or repulsions of the quiescent particles of matter on those of aether. If this be the sense in which Mr. Earnshaw uses the phrase, then I must understand from the above quotation that he has not es- timated the direct action of the particles of matter, simply because he has assumed that those particles vibrate, or rather perhaps, because he has assumed that they vibrate respectively in precisely the same manner as the particles of aether would do if they filled the same place. If this be the case, indeed, whatever Mr. Earnshaw assumes, the expressions for the ve- locity of transmission must contain a term due to the action of the particles of matter. Let us even take the extreme case of supposing that these particles are at rest, and that their attrac- tions or repulsions produce no effect : still is there an indirect effect due to them, which although not easily calculated, is clearly of the utmost importance. I allude to the effect due to the want qf action of particles of aether in the portions of space occupied by the material particles. Neither this, nor the pressure of the particles of matter on the adjacent particles of aether tending to stop their motion, does Mr. Earnshaw say one word about; and yet he asserts " that the indirect effect of matter is included in his equations." How is it included ? If it be replied, that the equations in p. 47 are supposed to contain terms dependent on the particles of matter, then is it evident that Mr. Earnshaw's argument is an antithesis to his premises; the latter being the expressions for the velocity of transmission in vacuo and in a refracting medium are different in form, the former, therefore the velocities themselves must have the same form. Now as I am not willing to accuse Mr. Earnshaw of any such reasoning, I am anxious to imagine on Theory of Molecular Action according to Newton's Law, 265 what his argument it based. I can only conceive it to be the assumption that the equation can in no case render y dependent on A. That Mr. Earn- shaw admits it does not in vacuo, is evident from the fact that he believes the equations he has deduced to be correct in that case. He says, Phil. Mag., May, p. 373, " these, then, are the equations of transmission of common light through any transpa- rent medium whatever." If I am right in my conjecture, then, I reply that Mr. Earnshaw is not at liberty to base so sweep- ing an argument as he brings forward on any assumption whatever, much less on one so little likely to be correct. I re- peat, that I am unwilling to suppose that Mr. Earnshaw has made use of any false reasoning, but I am convinced that any one who shall peruse his paper will agree with me in affirming, that with so few words devoted to explaining the influence of the particles of matter it is utterly impossible for any one to know what Mr. Earnshaw does mean. I am the more anxious to express this fully, that I may not be accused of misinter- preting the argument, and I trust it will have the effect of eliciting a more full and satisfactory statement. On the next remark of Mr. Earnshaw I shall not dwell. It has reference to the promised proof by Mr. O'Brien, that "the hypothesis of finite intervals cannot be correct," and to the adoption of the hypothesis of the direct action of the particles of matter. I shall only observe, that so far as I can see, the application of this hypothesis is insufficient, unless it be ad- mitted that the particles of " matter are compound, consisting of many different atoms," all of which vibrate along with the particles of aether. If you allow the same assumptions to the finite-interval theory, it will account for the same facts by a formula very much of the same kind. It is by this means that I accounted for dispersion in my 'Theory of Heat,' p. 152. The equations of motion of two sets of vibrating particles were first obtained by me in the Transactions of the Cambridge Philosophical Society, p. 237 et seq. The next matter to which I will direct attention has more pointed reference to myself. Mr. Earnshaw, in a paper printed in the Philosophical Magazine for April, points out the pro- cess which I had adopted in my first Memoir on Dispersion, and adds, " the remaining four lines are used as a test of the truth of the undulatory theory^' (P« 308). Where, and by whom, he does not state. For my own part, I disclaim any such unphilosophical opinion. What I hold is this : " that 266 Prof. Kelland's Reply to some Objections against the a theory which has succeeded so well in accounting for a great variety of intricate and delicate phenomena" (Earnshaw, p. 304), is strengthened by the removal of any obstacle, and con- sequently by bringing under it the explanation of the pheno- menon of dispersion. But has the phenomenon been ex- plained ? I answer, most assuredly. It is done as satisfactorily as almost any one phenomenon in nature is explained. Its doubtful nature, the "uncertainty J" which I mentioned in my 'Theory of Heat' as attached to it, is referable, not to the kindof explanation, but to its detail. Nay, even Mr. Earnshaw himself appears to look for a complete explanation to the very quarter at which he aims his objections. Unless Mr. Earnshaw adopts the hypothesis that the particles of matter are at rest, there is no difference whatever between the hypothesis of Mr. O'Brien, which he designates as a " more promising one," and my own. Are my equations then incorrect, and why ? I see them open at p. 248 of vol. vi.of the Transactions of the Camb. Phil. Soc, they are certainly not of exactly the same form as Mr. O'Brien's ; but his are only approximations. 1 do not say that even then they are identical, the difference probably will be removed by supposing B and B equal in the latter. So far as I am concerned with the numerical verification of the for- mulas for dispersion (which occupies between five and six pages in my Memoir), I may state that it is essential to show that our results are in the form which the phenomena require they should be : and having premised this, I will gladly answer the questions which Mr. Earnshaw puts me in p. 49. " Am I to understand him to say, that his formule are of necessity capable of producing correct results even if the data employed be erroneous ?" Yes : but the data are not erro- neous. " May I then ask, what is the nature of the connexion of these formule with theory ? and in what degree is his theory supported and strengthened by coincidences obtained from such formule?" The numerical verifications were used, as is stated at the place, as a test of the general accuracy of the deductions. Let me quote my own words. " Results more nearly agreeing might doubtless be obtained by proceeding to one place further in the expansion of sin — °, but the above will suffice to establish the general accuracy of the formula" (p. 174). " If, however, it were requisite to determine accu- rately the values of/>, a , . . . . of course the plan to be adopted would be that of introducing seven constants, and determining their values from the seven given equations" (pp. 172-3). " I wish to ask, then, how the results could have any power Theory of Molecular Action according to Newton's Law. 267 at all in confirming the theory, if the formulae were of necessity capable of producing correct results from correct or incorrect data indifferently?" In answering this question, I must premise that I fear I do not rightly understand what Mr. Earnshaw means by " from correct or incorrect data indifferently." Perhaps I shall make the matter more clear by putting an hypothetical case. The formula being general, admitting as many arbitrary constants as you please, is sufficient to satisfy any numerical results con- tinuous and not inconsistent with each other. This I presume will be allowed. Suppose, then, the results had been exactly the converse of what they are : suppose /n to have increased with A. The formula, then, could probably never have been made apparently applicable; and, although sufficient, would assuredly have been held as not at all probably true. By re- versing the process, and showing that a formula not only sa- tisfies the requisite demand, but does so in the most simple manner, we certainly add weight to its authority, and strengthen the process on which it is founded. I proceed now to the consideration of the other objections which Mr. Earnshaw has adduced, for the most part to my own results, in the same paper. They all originate in one and the same error which Mr. Earnshaw has fallen into in deducing his equations at p. 47. I dare say Mr. Earnshaw has himself discovered the oversight ere now, and, but that he has wielded the erroneous results to which it led him in dealing blows most at my conclusions, I should have left it to himself to supply the correction : but as Mr. Earnshaw has set his conclusions in opposition to the truth of my deductions, and those, too, of the most important kind, I cannot delegate the power of replying to his own convictions. The error I allude to is this. Mr. Earnshaw says, " We are now at liberty, without affecting the generality of our investigations, to suppose that the axes of symmetry were the coordinate axes employed in my former paper ; in which case D = E = F = 0," &c. (p. 47). Now it is not at all true that because the axes are axes of symmetry therefore D = E = F = 0. The method which Mr. Earnshaw has employed in his former paper (Phil. Mag. May, p. 373) to obtain his equations, is more similar to that which M. Cauchy uses to obtain the same equations in his recent publications, than to his original method. In his Nou- veaux Exercises, p. 4, for instance, he makes as Mr. Earnshaw does, without giving explicitly the value of F. 268 Prof. Kelland's Reply to some Objections against the But in his Memoire sur la Dispersion de la Lumiere (Prague), he gives the value of F as ^ f2mfr . 2 &rcos&\ . n\ S \—f— cos z3 cos y sin • — 2 — J" ^p" * Had Mr. Earnshaw seen this last value, he would hardly have conceived that it could be made zero by the symmetry of the axes : he would have been convinced that the relative values of /3, y, and 8, i, e. the relative directions of transmission and of the axes, alone could effect that object. The fact is, that if any one of the axes of coordinates coincide with that of trans- mission, the three quantities do vanish ; in other cases they do not. Mr. Earnshaw's oversight consists, then, in assigning to an axis of symmetry a property which belongs only to the axis of transmission. It is remarkable that Mr. Earnshaw did not inquire into the cause of difference between his equations and mine, for in form they are identical. [See Phil. Mag., May, 1837, p. 388, and various other places.] I say it is re- markable, for Mr. Earnshaw perceived that the cause of differ- ence lay in the dependence or want of dependence of the equa- tions of motion on the direction of transmission. All the argument he offers in support of his view is contained in the following words: — "Again, by referring to my former com- munication, it will be seen that the equations of motion do not depend upon the position of the front of the waves traversing the medium" (p. 47). And this is in reality all the reasoning on which he founds his remarks subversive of so many of my conclusions. One word will serve to answer it. Mr. Earn- shaw's former communication did not contain the equations of motion on which his arguments are founded. These are to be found only in the latter communication, and in a form which does depend on the position of the front of the wave. Having then shown that Mr. Earnshaw's argument is founded in a mistake, I will adopt his language (p. 48), modified to suit my own purpose : — I consider it therefore as proved incontestably, that according to the finite-interval theory there is a connexion between the directions of the vibrations and the law of molecular force. Hence, then, I have established the transversality of vibrations on that theory on a basis which defies opposition. Having thus shown that an error lies at the foundation of all Mr. Earnshaw's objections, it might be deemed unneces- sary to refute them in detail : yet since they are so plainly and prominently brought forward as opposed to my conclusions, I owe it to myself briefly to do so. They are, — 1. "The vibrations have no necessary reference to the di- Theory of Molecular Action according to Newton's Law. 269 rection of transmission." This is assumed by Mr. Earnshaw when he omits D, E, and F, and hence all his objections. 2. " There can be no connexion between the directions of the vibrations and the law of molecular force." It has been proved by me in the Transactions of the Cambridge Philoso- phical Society, vol. vi. p. 180, and Philosophical Magazine, May, 1837, p. 841, that if the law of force in a medium of symmetry be that of the inverse square of the distance, the vibrations must be altogether transversal or altogether normal. I call on Mr. Earnshaw to point out an error in my reasoning. 3. But Mr. Earnshaw has attempted to impugn, not in- deed my reasoning, but my inference. He says (p. 49, last line), " since v v' v" are the velocities of the wave, and not of the particles, the inference should have been, that there is one direction in which waves cannot be transmitted', or, in other words, that the cether is opa/ce in one direction." Mr. Earn- shaw ought, I repeat, to have attempted to show that there is some error in the argument, for he must know that such an inference as he draws tends to throw discredit (if legitimate) upon any reasoning from which it is made to follow. The hypothesis is that the aether is equally affected in all directions, the conclusion, that it is opake in one. The inference, however, cannot follow from my equations, for Mr. Earnshaw will see, if he turns to my Memoir, that o' is the velocity of a normal vibration which is assumed to exist. Since then (I argue) the normal vibration has not a possible velocity of transmission, it does not exist. In fact, if there be a normal motion at all it must be a transmissory one, due to exponential in place of circular functions. On this last fact I have based my Theory of Heat (Preface, p. 8, and Me- moirs, Sec, passim). Since Mr. Earnshaw quotes Mr. O'Brien, I will refer him to the same quarter to be set right, for his conclusions are equally controverted by Mr. Earnshaw's ob- jections. 4. " But I am unable to discover on what ground it is stated that y' is impossible," &c. Had Mr. Earnshaw read through the page he refers to he would have found the reason : all that he suggests is there plainly discussed, the inference that the cether is opa/ce in one direction only excepted. 5. Mr. Earnshaw concludes with a suggestion that the in- ference ought rather to have reference to the instability of the medium according to the Newtonian law. How he connects the impossibility of transmission of an assumed vibration with instability it is easy to see, and that it arises from the assump- tion of the want of dependence of the equations of motion on the direction of transmission. But I shall not dwell on this 270 Mr. W. H. Balmain on the Formation of Compounds of subject here. It has already been amply dealt with at the commencement of my reply : I will only add, when it is con- cluded from the hypothesis of a cubical arrangement of the particles, acting by forces which vary according to the New- tonian law, that the direction of one side of the cube is stable and of one unstable (Earnshaw on the Nature of Molecular Forces, Art. 15), ought we not to ask, Is it the hypothesis, or the reasoning based on it which is erroneous ? Must it not of necessity be the latter ? We have now done with the objections to the statical pos- sibility of the law. It remains to reply to the two objections to its dynamical applicability. It is fit that a matter so im- portant as the rejection of a law which explains so many phe- nomena (see Gauss, in the last No. of the Scientific Memoirs), which has so strong an d priori probability, and which is the proved law of material action, should rest on none but the most unexceptionable evidence. Whatever may become of the question ultimately, I trust that by rigidly examining that evidence which has been afforded and showing its inadequacy, I shall be considered as actuated by no captious or unphilo- sophical spirit. My next communication will be a reply to M. Cauchy, whose arguments being based on a refined ana- lysis, can scarcely be answered without the use of similar means. [To be continued.] XL VI. Observations on the Formation of Compounds of Boron and Silicon with Nitrogen and certain Metals. By W. H. Balmain, Esq., Lecturer on Chemistry in the Mechanics' Institution, Liverpool*. /CONSIDERING the strong affinity existing between hy- ^ drogen and nitrogen, and between carbon and nitrogen, together with the circumstances under which they will com- bine, and their chemical relations to boron and silicon, I was led to imagine that the two latter elements must have a very strong affinity for nitrogen, and concluded that they might be caused to combine with it by double decomposition ; and, bearing in mind the strong affinities of ammonia and cyano- gen, it appeared probable that the compounds, if obtained, would play an important part as chemical agents ; and I had hopes that some of the bodies at present supposed to be ele- mentary might prove to be compounds of nitrogen with these or other elements. Some experiments instituted to establish these points have been in a measure successful, but as they form only a small part of the great number which will at once * Communicated by Dr. Kane. Baron and Silicon with Nitrogen. 271 suggest themselves to the mind of the chemist, and as my time is of necessity devoted to other objects and my means very limited, I beg leave to lay the few facts which I have been able to ascertain before the working chemists of the day through the medium of the Philosophical Magazine. Silica and boracic acid undergo no change when heated in ammoniacal gas by means of the oxyhydrogen flame nearly to the point at which platina melts, but when heated to that temperature with cyanide of potassium instead of ammonia, apparent action ensues. Boracic acid and cyanide of potas- sium, in the proportion of two atoms of the former to three of the latter, were placed in a covered porcelain crucible, that inclosed in a larger Hessian crucible, and the space between being filled with small pieces of charcoal, the whole was heated to whiteness in a wind furnace. The result was a white porous substance, which was found not only at the bottom of the cru- cible, but also lining the sides and the top, having been carried there by spurious sublimation. The relative quantities given above were used in order that the carbon of the cyanide might be exactly in the right proportion for taking all the oxygen from the boracic acid and forming carbonic oxide only, and when by accident an excess of boracic acid or cyanide was employed it appeared to remain as an impurity in the white solid; but these points were not closely examined, because the white solid, which was homogeneous and evidently a distinct and stable compound, was a more interesting object of study. The fol- lowing is the best process for preparing it : — Take seven parts of finely powdered anhydrous boracic acid and twenty parts of cyanide of potassium free from water, and as far as possible from cyanide of potass and iron ; and having lined a Hessian crucible with a paste of powdered charcoal and gum, and heated it until all water has passed away, place the mixture in the crucible, cover it by inverting and luting a smaller cru- cible over it, and heat it to whiteness for an hour : it is ad- visable to use a crucible as a cover, that there may be suffi- cient room for spurious sublimation, and the vent-hole should be bored in the bottom of this crucible and not in the luting at the side; and further, to avoid the penetration of oxygen to the materials, it is well to line the upper crucible in like manner with the lower. The result found in both crucibles, when washed and dried, will be the white solid in a state of purity. It is a light porous solid which readily falls to powder, and when compressed, presents that peculiar sur- face which is observable in some of the precipitated cyanu- rets, and in a slight degree in chloride of silver, and in some iodides, &c. ; it is infusible, insoluble, even when heated, in water, in solution of potass, hydrochloric acid, sul- 272 Mr. W. H. Balmain on the Formation of Compounds of phuric acid (strong and diluted), nitric acid, and solution of chlorine ; it is not altered upon exposure to air, nor does it affect the most delicate turmeric paper when left upon it in a moist state. Passing over for the present the remarkable sta- bility of this compound, these characters are important as proving the absence of boracic acid and cyanide of potassium (with some results it was found necessary to wash away the excess of cyanide of potassium; but this does not interfere with the nature of the white solid, and was not necessary when the boracic acid and cyanide of potassium were quite pure and free from water, and their proportions very carefully adjusted). Heated with hydrate of potass or soda it yields ammonia abundantly ; in the deoxidizing flame of the blow- pipe it is not altered, nor does it communicate any colour to the flame, but in the oxidizing flame it gives a strong green colour, and gradually fuses, yielding a perfect bead, which is transparent, hot and cold, and when placed with a drop of water upon test papers, turned tumeric brown, and red litmus blue. When the outside flame impinges upon a large surface of the substance in powder, as when a glass tube soiled with it is held at the extreme point of the flame, it pre- sents a beautiful green phosphorescence, owing no doubt to the gradual formation of boracic acid at the surface, and if it be removed to the inner flame, the centre will incandesce, while the outer edges, where it meets with the oxygen of the air, will still yield the elegant green. When thrown upon fused chlorate of potass it deflagrates with a soft green light, and it will also deflagrate with nitrate of potass. It is not altered by being gently heated with potassium or sodium, nor when heated before the blowpipe on charcoal, with lead, zinc, &c. Chlorine has no action upon it at a low red heat, and iodine, sulphur and corrosive sublimate may be sublimed from it without decomposing it. It is not decom- posed by hydrogen at a red heat, but below that temperature is decomposed with the evolution of ammonia by the vapour of water, or by any substance which will yield water, as hydrate of potass, hydrate of lime, common clay, hydrated phosphoric acid, and the rhombic phosphate. It is not de- composed by hydrochloric acid at a low red heat, and I think it is not altered by hydrofluoric acid, for a small portion of it was mixed with a large quantity of fluorspar, with more than sufficient sulphuric acid to make it all into hydrofluoric acid, and heated as long as fumes passed offj when, after the sul- phate of lime had been washed away with dilute nitric acid, it still yielded ammonia with hydrate of lime. From some of these facts it appears that the compound con- tains boron, nitrogen, and potassium, and I suppose that the Boron and Silicon with Nitrogen. 21 S nitrogen and boron are united, and that the compound so formed is combined by a very strong affinity with potassium. My inability to obtain a better balance than such as I could construct myself of wood and paper, or suitable apparatus for an analysis, prevents me from speaking at all positively as to the proportion of the elements ; but some analyses and decom- positions seem to point out the proportion K3 N3 B2 as the correct one, from which it would appear that during its pre- paration there is no loss either of potassium or of nitrogen; nothing passing off but carbonic oxide : (2 B Oa and 3 (N C2 + K) = N3 B2 K3 and 6 C O). This theory very nearly agrees with several estimations of the quantity of ammonia and boracic acid found when the compound is decomposed by the hydrates of lime and potass, and is corroborated by there being no gas but ammonia dis- engaged, and no boron deposited during the decomposition : (N3 B2 K3 and 9 H O = 2 B Os + 3 K O and 3 N H3). However, it may be that there are only two atoms of potas- sium, since the compound can only be obtained at such a tem- perature as would volatilize potassium ; from which it would appear that potassium was set free during its formation ; and moreover, during the decomposition by hydrate of potass or lime, a new compound is formed which may' possibly contain the original compound with oxygen, being somewhat analo- gous to cyanate of potass, in which case the oxygen, set free from the hydrogen which has to form ammonia, might be theoretically disposed of without the supposition that there are three atoms of potassium (N3 B2 K2 and 9 H O = 2 B 03 + 2 KO and 3 N H3 and O, which would go to undecomposed substance); but at the same time, this new compound may contain oxygen and have derived it, not from the decomposed water, but from the air in the vessel. It is formed when the "boronitruret of potassium" is fused with potass, and an excess of acid added to the solution of the result ; at first it appears as a milkiness in the liquid, but by continued ebullition, col- lects into a distinct precipitate,which when dry is a remarkably coherent thready solid. When heated before the blowpipe it gives a strong green flame without melting ; it yields ammonia abundantly with hy- drate of lime and carbonate of potass (a mixture which I used instead of hydrate of potass), and in other respects behaves like the " boronitruret of potassium," excepting that it yields no phosphorescence, and when slowly oxidized forms a very fusible bead, which during its oxidation throws out small ve- sicles owing to the escape of gas. The substance operated Phil. Mae. S. 3. Vol. 2 1 . No. 1 38. Oct. 184-2. T * 274 Mr. W. H. Balmain on the Formation of Compounds of upon was obtained chiefly from an incomplete analysis of the " boronitruret of potassium," by heating it with hydrate of lime; the result being diffused through water, a stream of carbonic acid passed through it, and the whole boiled, borate of potass was in solution and carbonate of lime precipitated, which, being acted upon by muriatic acid, yielded an imper- fectly transparent liquid, and from this the thready substance was deposited on long-continued ebullition. All attempts to decompose the " boronitruret of potassium," so as to isolate the theoretical " boride of nitrogen," have hitherto been unsuccessful ; each experiment adding its testi- mony to the remarkable stability of the compound. It can- not be done by means of oxidizing agents, for both the potas- sium and the boron take oxygen at the same time, and either boracic acid and potass are formed, or else the thready substance alluded to above, as appeared to be the case when peroxide of manganese with boracic or sulphuric acid was used as the oxidizing agent, since, after diluting and acting upon the re- sidue with a solution of oxalic and sulphuric acids to remove boracic acid and any remaining peroxide of manganese, a white solid was left which had the same appearance and, before the blowpipe, the same characters as that substance. Finding that cyanogen passed over a mixture of boracic acid and charcoal heated to redness gave me no result, I en- deavoured, as a last resource, to obtain compounds of " boride of nitrogen" with the common metals by heating their cy- anides with boracic acid, fully expecting that these cyanides would decompose at too low a temperature for the deoxidation of the boron to take place, and I was agreeably surprised when upon trial it appeared that the cyanide of copper heated with boracic acid gave a result, which, after being washed, yielded ammonia when heated with a mixture of hy- drate of lime and carbonate of potass; and cyanide of lead, a result which not only yielded ammonia, but produced a phos- phorescence before the blowpipe which differed from that of the " boronitruret of potassium " only in its colour, which was more yellow and less green. Both of these results were so impure, owing to the presence of oxides in the cyanides, that their characters could not be taken as those of the compounds of the metals with " boride of nitrogen," and they were only valuable as proving the possibility of making those compounds by such a process. The copper result gave a very fine green flame before the blowpipe, but would not phosphoresce ; and after the metallic copper had been removed by nitric acid a substance remained which appeared more like the "thready compound" supposed Boron and Silicon with Nitrogen. 275 to contain oxygen, than the " boronitruret of potassium." Cyanide of mercury heated with boracic acid gave cyanogen abundantly, which burned with a tinge of green in its flame ; and at the same time a small quantity of white crystalline solid sublimed, which may prove to be a compound of mer- cury with the M boride of nitrogen," and being such, if it could be obtained in larger quantity, might probably be a means of isolating the much-wished for " boride of nitrogen." It was soluble in water, giving it a bitter taste ; and the solution gave no precipitate with a salt of iron, but an abundant white with protochloride of tin : with iodide of potassium none, with acetate of lead none, with nitrate of silver a slight precipitate, which was insoluble in excess of acid. It was likewise soluble in alcohol, but the solution did not burn with a green flame. Boiled with a solution of carbonate of potass it yielded am- monia, and it communicated a green colour to flame, passing off rapidly in vapour, and giving a greenish blue colour to the flame in its immediate neighbourhood. A mixture of one part of anhydrous boracic acid with two and a half parts of cyanide of zinc, heated to whiteness in a lined crucible (covered and well luted), yielded a white solid similar in appearance to that obtained by heating a mixture of boracic acid and cyanide of potassium. It gave ammonia abun- dantly when heated with a mixture of hydrate of lime and car- bonate of potass, and was insoluble (with and without heat) in water, sulphuric acid, hydrochloric acid, nitric acid, solution of chlorine, solution of potass and ammonia. It is not decomposed by chlorine at ajicll red heat, nor by corrosive sublimate, nor by potassium or sodium. Before the blowpipe it is infusible, but in the oxidizing flame communicates a green colour, and when at the outer edge emits a very brilliant bluish phos- phorescence, which appearance it also produces when simply dropped into the flame of a spirit-lamp. Thrown on fused chlorate of potass it deflagrates with a faint blue light. These characters are exactly such as we should expect to find in a compound of zinc with " boride of nitrogen " analogous to the compound of potassium. It appeared to be in a state of purity, and is more readily obtained than the potassium com- pound, since the preparation of a pure cyanide of zinc is ac- complished with greater facility than that of cyanide of potas- sium. Besides its interest in being distinctly a second com- pound of the kind, and the remarkable beauty of its phospho- rescence before the blowpipe, it is of importance as affording a means of preparing the analogous compound of other metals by heating it with their chlorides. Heated to whiteness in a lined crucible in the proportion of one atom of itself (taking T2 276 Compounds of Boron and Silicon with Nitrogen. its composition to be Zn2 N3 B2) to two atoms of the chloride, it yielded, with chloride of lead, a white solid which gave ammonia abundantly when heated with a mixture of hydrate of lime and carbonate of potass, and phosphoresced with a yellowish green light at the point of the blowpipe flame ; water boiled with it afterwards gave no precipitate with nitrate of silver, and when it was heated before the blowpipe with soda upon charcoal, it gave a distinct button of lead and only a minute trace of zinc ; with chloride of copper, a result similar to that obtained by heating together cyanide of copper and boracic acid. With chloride of silver, a result which resembled the lead compound, and phosphoresced brilliantly with a yellowish - green light. It was not decomposed by hydrochloric acid, nor by chlorine at a low red heat, nor by corrosive sublimate, and indeed appeared under all circumstances as stable as the rest, remaining unaltered even when heated in a tube with sodium and potassium. With the chlorides of sodium, ba- rium, strontium, calcium and manganese, results which ap- peared to be " boronitrurets" of those metals ; but in these cases the experiments were made with small quantities, solely with a hope of finding a soluble compound ; and as not one of them would yield ammonia when boiled in water with hy- drate of lime and carbonate of potass, and as water after ebullition in contact with them gave no precipitate with so- lutions of the oxides of lead, silver, copper, iron, &c, I con- cluded that I had not been successful in my search. Six parts of silica heated to whiteness with thirteen parts of cyanide of potassium gave a brittle porous vitreous solid, which, after being well washed, yielded ammonia abundantly when heated with hydrate of lime and carbonate of potass. Heated with fused potass it yielded ammonia abundantly. After ebullition with sulphuric acid it still yielded ammonia when heated with hydrate of lime and carbonate of potass. In the deoxidizing flame it fused tranquilly, and in the oxidi- zing with escape of gas. With carbonate of soda it gave a red bead in the deoxidizing flame, the colour of which disap- peared in the oxidizing flame, and could not be recovered. After being heated with nitrate of ammonia and well washed, it yielded ammonia with hydrate of lime and carbonate of potass, more abundantly than before. From this it appears that a compound of silicon and nitrogen with potassium ana- logous to the boron compound had been formed, and that it is nearly as stable as that substance ; but as I had no means of separating the compound from impurity, nothing further can be said at present. Prof. Miller on Tourmaline, Dioptase, and Anatase. 277 From the above results, and from a few doubtful experiments which have not been mentioned, I conclude that compounds of nitrogen with boron and silicon had been formed, and that their chemical relations are similar to those of cyanogen; and I have no doubt that analogous compounds of alumi- nium, glucinium, &c. may also be formed ; moreover, I have hopes that the fundamental principles of the science of che- mistry may be further elucidated by some of these compounds proving to be, if not some of our " elements," at least of a nature closely analogous. We are not to suppose that the affinity of nitrogen for the other elements is weak because it will not unite with them directly as by a process of combus- tion, especially as the compounds of nitrogen at present known are not formed directly, and in many the affinity has proved stronger than was at first supposed. This compound of boron and nitrogen resists all agents but oxygen, and analogous compounds with bases not so easily oxidized might appear to us elementary, and a glance over the relative constitution of our earth and atmosphere may in some measure justify us in expecting to find nitrogen abundantly in the mineral king- dom; and this point decided positively, may throw much light upon the connexion between organic and inorganic chemistry. My opinion is founded upon a careful review of many well- known facts, and is not solely dependent upon these recent experiments for its support, but, on the contrary, they have been instituted to discover evidence, and I hope that while my labours are still continued others will be induced to join in the same pursuit. William H. Balmain. XL VI I. On the Optical Constants of Tourmaline, Dioptase and Anatase. By W. H. Miller, M.A., F.R.S., Professor of Mineralogy in the University of Cambridge* . r|^HE values of the optical constants of Tourmaline were deduced from observations made with a prism cut out of a colourless crystal in the possession of Mr. Brooke, which, though not sufficiently perfect to show the dark lines in the spectrum, exhibits the bright line in the flame of alcohol very distinctly. For this light the index of refraction of the ordi- nary ray out of air into the crystal is 1*6366; in an extraor- dinary ray perpendicular to the axis of the rhombohedron the velocity of light in air divided by its velocity within the cry- stal is T6193. A slice of the same crystal bounded by planes perpendicular to the axis, 0*68 inch thick, being placed in a po- * Communicated by the Author. 278 Notices of the Labours of Continental Chemists: Cerium, ^c. larizing apparatus, the diameter in air of the darkest part of the first ring is about 7° 30'. When this mineral is coloured, as is usually the case, the optical constant belonging to the extraordinary ray cannot be determined, on account of the absorption of the light polarized in the plane of the axis. In Dioptase, according to observations made with a very perfect and transparent crystal, for which I am indebted to Mr. Heuland, for the brightest part of the solar spectrum the index of refraction of the ordinary ray is 1*667; in an extra- ordinary ray perpendicular to the axis the velocity of light in air divided by its velocity within the crystal is 1*723. In Anatase, for the brightest part of the solar spectrum, the index of refraction of the ordinary ray is 2*554; in an ex- traordinary ray perpendicular to the axis, the velocity of light in air divided by its velocity within the crystal is 2*493. St. John's College, Sept. 9, 1842. W. H. MlLLER. XLVIII. Notices of the Results of the Labours of Continental Chemists. By Messrs. W. Francis and H. Croft. [Continued from p. 21.] On Cerium and some of its Salts, and on Didymium. \ N examination respecting the true atomic weight of cerium ■^*- has been made by M. A. Beringer in the laboratory of Professor Wohler ; new experiments on this subject were ne- cessary on account of the discovery of lanthanium. It will however be useless to insert this treatise in these reports, inas- much as a notice has appeared in PoggendorfF's Annals, vol. lvi. p. 503, from which we learn that Mosander has discovered a third metal mixed with cerium and lanthanium, which he calls Didymium. It is scarcely possible to separate the oxide of this metal; Mosander, although he has known this body one year and a half, has as yet been unable to isolate it in a pure form. Oxide of didymium causes the brown colour of the so-called oxide of cerium, and also the rose or amethyst tinge of some salts of yttria. The perfectly pure oxides of lanthanium and cerium are probably quite colourless. In the usual mode of preparing oxide of lanthanium by means of dilute nitric acid, the whole of it is never extracted, but part remains with the oxide of cerium. Mosander is engaged with the examination of the three bodies, and from him we may expect a full description. Beringer has examined metallic cerium (impure), the double sulphates, and some other salts. — (Antialen der Chemie und Pharmacie, vol. xlii. p. 134.) Atomic Weight of Chlorine, — Hyposulphites. 279 On the Atomic Weight of Chlorine, Zinc, $c. Laurent has made some experiments on the atomic weight of chlorine; the assumption of Berzelius's number agrees completely with the analyses, while considerable differences are visible if the atom be considered as a multiple of that of hydrogen. Marignac determines the atomic weight by pass- ing hydrochloric acid gas over heated oxide of copper ; he finds 225*013, or thirty-six times that of hydrogen. From this he reckons the atomic weight of silver 1374*0, and of potassium 498*5. Jacquelain finds the atomic weight of zinc to be 414. — {Comptes Rendus, Mar. 1842, p. 456; Ibid, Avril 1842, p. 570; Ibid. Mai 1842, p. 636.) On the Hyposulphites. Rammelsberg has published an examination of this class of salts : the deliquescent potash salt has the formula 3 KS + H. The soda salt contains 5 atoms of water, that with ammonia has the same composition as the potash salt. The baryta salt contains 1 atom of water, that with strontia 5 atoms, with lime and magnesia 6 atoms. A deliquescent double salt of magnesia and potassa has the formula K S + Mg S + 6 aq. Hyposulphite of manganese decomposes on evaporation into sulphur and sulphate, the zinc salt the same ; a compound of the zinc salt may be obtained by adding ammonia in excess to a solution of the hyposulphite and precipitating the salt by alcohol ; it is Zn S + N H3. The nickel and cobalt salts have the same constitution as the magnesia compound ; the nickel salt combines with ammonia, and gives (Ni S + 6 H) + 2 N H3. Hyposulphite of lead dissolves in solutions of alkaline and earthy hyposulphites, and forms double salts which are easily decomposed. Their solutions must not be heated, for then sulphuret of lead is formed ; they are partly decomposed by water. The potassa salt is Pb S + 2 K S + 2 aq, the ammonia salt Pb S_+ 2 N H4 O S + 3 aq. The soda salt has been de- scribed by Lenz {vide the last Report) . Salts may also be form- ed with baryta and strontia; the lime salt is Pb S + 2CaS + 4aq. Hyposulphite of oxide of mercury cannot be obtained ; but by digesting the oxide with solutions of hyposulphites double salts are formed ; the ammonia and potassa salts crystallize, the former is HgS + 4 N H4OS + 2aq ; the formula of the potassa 280 Notices of the Labours of Continental Chemists, salt is rather uncertain ; the soda salt does not crystallize, nor do the compounds of the earthy hyposulphites. A solution of the potassa double salt added to sulphate of copper causes a brownish-red precipitate, which has the same formula as the potassa salt, viz. 3 Hg S + 5 Cu S. On adding hyposulphite of potassa to sulphate of copper a yellow precipitate is produced, the formula of which is K S -f Cu £H- 2 aq ; it dissolves in excess of alkaline hyposulphite and alcohol precipitates from this solution another crystalli- zable salt, 3 K S + Cu S + 3 aq. A soda salt similar to the first of these has been described by Lenz, it dissolves in excess of Na S, and gives 3 NaS + Cu S + 2 aq. Rammelsberg has also examined the products of the de- structive distillation of the hyposulphites ; he finds that sul- phurets, sulphates, and sometimes sulphites are formed. — (Poggendorff's Annalen, vol. xlvi. p. 295.) On the Sulphocyanurets. Meitzendorff has made an extensive series of experiments on these salts, under the direction of Rammelsberg. The acid was obtained by distilling the potassium salt with tar- taric acid. We will here only mention the chief peculiarities of the salts, and refer the reader for fuller information to the long paper itself. The ammonium and sodium salts are an- hydrous, Na, Cy S2 and N H4, Cy S2. The barium, stron- tium, magnesium and calcium salts are crystallized and deli- quescent, Ba, Cy S2 + 2 aq, Sr, Cy S2+ 3 aq, Ca, Cy S2 + 3aq, and Mg, Cy S2 + 4 aq. The solution of the aluminum salt is decomposed by evaporation into an insoluble basic and a so- luble neutral salt. The crystallized manganese salt contains 3 atoms of water; the zinc salt is anhydrous, it combines with ammonia, forming a salt which crystallizes in beautiful cry- stals, it is Zn, Cy S2 + N H3. Cobalt salt does not crystallize, it is 2 Co, Cy S2+ H ; it forms two compounds with ammonia. The nickel salt has the same composition, and the anhydrous salt forms with two atoms of ammonia a crystallizable salt. The crystallized cadmium salt is anhydrous, combines with one atom of ammonia. There are two salts of bismuth, Bi, Cy S2 and Bi, Cy S2 + 4 Bi + 2 aq. The rf/sulphocyanuret of copper is anhydrous, but retains a little moisture with great On the Sulphates of Alumina and of Chromium. 281 obstinacy. The sulphocyanuret may be obtained by using very concentrated solutions of the sulphate of copper and the sulphocyanuret of potassium ; it is precipitated as a black pow- der, and is anhydrous. Its decomposition with water, which has been studied by Claus, is very curious ; it changes in water into the white disulphocyanuret ; it appears that at the same time hydrosulphocyanic, hydrocyanic and sulphuric acids are formed (the iron salt appears to be similar in properties). The sulphocyanuret of copper forms a crystallizable salt with, one atom of ammonia. — (PoggendorfPs Annale?i, vol. xlvi. p. 63.) On the Sulphates of Alumina and of Chromium. In the 45th volume of PoggendorfPs Annals, page 99, Hertwig published apaper on the proportions in which alumino- sulphate of potassa (alum) can combine with water; he found that when large crystals of common alum are allowed to lie for some time in concentrated sulphuric acid they are not dissolved but dispersed through the acid, forming a gelatinous mass; water throws down a crystalline powder, which on being pressed between bibulous paper and recrystallized from a hot solution, gives a salt in the form of regular octohedrons, which contains only 14 atoms of water, whereas the common alum contains 24. In the same volume, page 331, there is a paper by Heintz who has not been able by these means to procure anything but common alum (Al S3, K S + 24 aq). By the united action of heat and sulphuric acid Hertwig obtained an- other compound, Al S3 + K S ■+• 3 aq, which is a very insoluble salt, and becomes still more so when strongly heated; it must therefore be an isomeric modification of anhydrous alum. Common alum when kept for a length of time at a tempera- ture of 100° C. loses 10 atoms of water, but this salt differs considerably in its properties from that with 14 atoms of water mentioned above. By a heat of 120° to 160° a com- pound of 5 atoms is obtained, at 200° with 1 atom. By somewhat similar means to those employed by Hertwig, Heintz has obtained two salts with oxide of iron, Fe S3, K S + 3 aq and Fe S3, K S + 2 aq. The true colour of the iron alum appears to be violet, when mixed with common alum it is quite white. In vol. lvi. of the same Journal, p. 95, Hertwig has described some modifications of the chrome alum. If a very concentrated solution of the green double sulphate be evaporated with concentrated sulphuric acid as long as water is driven off, a green anhydrous chromosulphate of potassa is 282 Notices of the Labours of Continental Chemists. precipitated, which is insoluble in boiling or cold water, hydro- chloric, sulphuric and nitric acids ; it is not altered by am- monia, but it is decomposed by boiling with caustic potassa ; formula, Cr S3, K S. It is easily decomposed by heat. It is evident therefore that the chrome alum can exist in three dif- ferent isomeric modifications. When chrome alum is heated at 200° C. as long as water is driven off, a " difficultly soluble" green modification is formed ; it contains 2 atoms of water ; it is insoluble in cold water, and also in sulphuric and hydro- chloric acids, but it is dissolved by continued boiling with water ; decomposition is also effected by boiling ammonia. When heated to 300°-400° it passes into the " insoluble" modification, its dark green colour changes to light green, and it has lost all its water. This anhydrous salt differs from that obtained with sulphuric acid, inasmuch as by long boiling with water, sulphate of potassa is dissolved and insoluble sulphate of chromium remains behind. In vol. xliii. of the same Journal, p. 513, Schrotter has de- scribed some sulphates of chromium. Cr S2 is obtained by adding as much hydrated oxide of chromium to sulphuric acid as it can take up when kept boiling for a long time ; it is not crystallizable, and forms a green mass on evaporation ; on the addition of water a light green powder separates, which is Cr3 S2 + 1 2 aq. If a solution of the first salt be heated with excess of sulphuric acid the green colour disappears and a peach red precipitate is formed, which is not soluble in water, and is not decomposed by acids or ammonia, but easily by caustic potassa or soda. A solution of this salt may be obtained by dissolving eight parts of oxide in nine parts of English sulphuric acid; alcohol does not precipitate the fresh solution ; if it be allowed to stand several weeks it forms a greenish blue crystalline mass, which dissolved in water forms a dark blue (by transmitted light ruby red) solution. Out of this alcohol precipitates a light violet-coloured crystal- line salt, Cr S3+ 15 aq, which is easily soluble in water, be- comes green when heated to 100°, and loses 10 atoms of water. For preparing the chrome alum, Schrotter proposes to pass sulphurous acid into a solution of one atom of bichromate of potassa and one atom of sulphuric acid, as long as it is ab- sorbed, the mixture being kept cool. He has also prepared the ammonia and soda chrome alum ; they both contain 24 atoms of water. [The ammonia compound was prepared by Mr. Warington several years ago {vide Turner's Chemistry).; On some Chromates. 283 it has also been examined by Mitscherlich ; vide Lehrbuch, vol. ii. part 2.] Hydrated oxide of chromium dried at 100° contains six atoms of water. Schrbtter also states that the green modifi- cation of chrome alum when in solution passes gradually into the blue one. [This- statement I can fully confirm from my own old observations. This change of the green into the blue oxide accounts for Warington's preparation of the double oxalates of chromium and potassa by means of green oxide of chromium*, although from the mode of preparation it is evi- dent that the blue oxide is the base in the black and red ox- alates.— H. C] On some Chromates. Kopp has examined several of these salts, principally with a view to determining their specific gravities and atomic volumes. The chromates of zinc and copper may be obtained by dissolving the oxides or carbonates in dilute chromic acid (prepared by Fritzsche's method), or by digesting chromate of baryta with the sulphates [several salts of the magnesian class were prepared some years since in this manner by Mr. Play fair, but no account of them has been published]. The salts of copper and zinc have the same form and composition as the sulphates of those oxides ; the soda salt is similar to the sulphate, it deliquesces. By evaporating its solution at 30° C. anhydrous chromate may be obtained. The chromates of am- monia and magnesia are precisely similar to the corresponding sulphates. — (Annalen der Chemie, Sfc, vol. xlii. p. 97.) Benschhas published a notice on some basic chromates ob- tained by pouring a solution of chromate of potassa into boil- ing neutral metallic solutions. These precipitates must be washed with hot water, or else they retain some potassa ; by boiling they appear to be decomposed. None of them have been properly examined as yet ; the manganese salt is black, its formula is Mn2 Cr + 2 aq. When heated red-hot the water and some oxygen are driven off. — (PoggendorfFs An- nalen, vol. 1. p. 97.) [The same salt appears to have been formed by Mr. Wa- rington (Reports of the Chem. Soc, part 3), who has obtained the same formula. Salts of protoxide of manganese are white or pinkish ; the salts of chromic acid are seldom very dark- coloured, and it appears rather anomalous that this basic salt should be black. It might be Cr 02 + Mn2 03+ 2aq; when treated with hydrochloric acid the sesquioxide of manganese would cause evolution of chlorine, and a brown chloride of chromium might be produced, which by the addition of alco- * See p. 201 of the present volume.— Edit. 284 Notices of the Labours of Continental Chemists. hoi would be reduced to the green chloride ; this agrees with Warington's experiments. — H. C] On Glucinium and its Compounds. Awdejew has made a series of experiments on the salts of glucina, under the direction of H. Rose. Great care was used in the preparation and analysis of the chloride of glucinium. It was found to contain 87*54 per cent, of chlorine, whereas it has been supposed to contain only 66*70. When dissolved in water it forms hydrochlorate of glucina ; on evaporating the solution a crystalline mass is obtained which has the composi- tion GC1 + 4 aq. [Awdejew supposes the oxide to contain one atom of oxygen.] The atomic weight of the oxide was de- termined from the analysis of the neutral sulphate, which is obtained by dissolving the carbonate in excess of sulphuric acid and separating by alcohol ; the salt is precipitated and may be dissolved and recrystallized ; its formula is G S + 4 aq. The atomic weight of glucina is, according to these analyses, 158*084, and that of the metal 58*084. A double sulphate of glucina and potassa may be obtained by gently evaporating a mixture of equal atoms of the two sulphates ; it is decom- posed by boiling, slowly soluble in cold water. Its formula is KS + GS + 2aq. Itmightbe 3 K S + G S3, but KS+J} S3 cannot be formed. The double fluoride of glucinium and potassium was also analysed ; it is K F + G F ; it is anhydrous, difficultly soluble. There are three basic sulphates which have been described and analysed by Berzelius (Lehrbuch, iv) . These formulas, according to the new equivalent, are G3 S, G2 S and G6 S + 3 aq. At the end of his treatise Awdejew consi- ders how the formulas of minerals containing glucina are af- fected by this change in the atomic weight. Chrysoberyll becomes G Al; phenakite G3 Si; beryll GPSi + Al Si; euklas 2 G3Si +A12 Si; leucophane G3 Si+Ca3 Si2 + Na F — (Pogg. Ann., vol. lvi. p. 101.) In vol. 1. of the same Journal Count Schaffgotsch published some experiments on glucina. He analysed the hydrate, and gave as its formula G-f8aq; according to the new atomic weight G3 + 4 aq would agree best with the analysis ; the oxide is dissolved by concentrated caustic potassa, and is not precipitated by boiling, unless the solution be diluted, when the whole is thrown down. By boiling the solution of glucina Action of water on Sulpkurets and haloid Salts. 285 in carbonate of ammonia a granular salt is precipitated, for which Schaffgotsch proposes the formula 2 G C3 H6+ 3 G H6"; this complex proportion becomes somewhat more simple if we tal^e the new equivalent, when we find it to be G C, H + 4-GH. In the same volume is also a paper by Ch. Gmelin on some properties of glucina. Action of Water on certain Sulphurets and haloid Salts. H. Rose has published a most interesting paper on this subject ; most of the experiments were made with sulphuret of barium, which was prepared by strongly heating a mixture of charcoal and sulphate of baryta. tThe black mass was treated in a closed bottle with a quantity of water far insufficient to dissolve all the sulphuret ; after standing twenty-four hours it was decanted and a fresh portion added, and this repeated nine times ; each portion was kept separate. The first and second solutions contained hydrosulphuret of barium (H S, Ba S), which was proved by the evolution of sulphuretted hy- drogen, on adding to them a concentrated neutral solution of sulphate of manganese; the sulphur was oxidized by treating the salt with hydrochloric acid and passing the sulphuretted hydrogen into strong nitro-hydrochloric acid ; the sulphur was thus perfectly oxidized. A stream of air was passed through the solution to carry over all the hydrosulphuric acid, and then chlorine passed into it to oxidize any sulphur.- The oxidized fluids mixed together, the sulphate of baryta sepa- rated; in the filtered liquor a large precipitate was produced by chloride of barium. The third solution gave only a slight smell of H S, with sulphate of manganese, but a copious evo- lution with hydrochloric acid. Chloride of barium (as above) produced only a slight precipitate; it contained therefore sulphuret with a small portion of hydrosulphuret. The fourth gave no trace of S H with sulphate of manganese, abundance with hydrochloric acid ; no precipitate was produced by chlo- ride of barium, but a slight one by sulphuric acid ; it con- tained therefore sulphuret and baryta. The fifth contained less sulphuret and more baryta, and the others only a trace of sulphuret. When large quantities of sulphuret of barium are boiled with water the same products are obtained ; some- times hydrate of baryta crystallizes, sometimes sulphuret, and sometimes compounds of both ; the hydrosulphuret is the most soluble product. The composition of one compound, which Notices of the Labours of Continental Chemists. formed good crystals, was Ba H10 + 3 Ba S, H6. Another gave the formula 4 Ba H10 + 3 Ba S, H6; a third appeared to be Ba H10 + Ba S, H10; but it is possible that the last two were only mixtures. Sulphuret of barium crystallizes with six atoms of water ; water acts upon this salt in the same manner as upon the re- duced sulphate of baryta. The sulphuret can hardly be ob- tained free from hydrate of baryta. The solid hydrosulphuret of barium was not analysed,as it cannot be obtained free from supersulphurets, sulphuret and hydrate of baryta. It appears therefore that sulphuret of barium is decom- posed by water and forms hydrosulphuric acid and baryta ; the affinity which the H S has for the sulphuret causes the separation of baryta, which crystallizes, sometimes as hydrate, and at other times in combination with the sulphuret. Sulphuret of strontium, as formed from sulphate and char- coal, is decomposed in the same manner as that of barium ; the more difficult solubility of the hydrate of strontia causes it to be separated from the other salts with great ease. H. Rose could obtain neither sulphuret of strontium nor its com- pound with strontia ; the sulphuret is decomposed by boiling into the earth and the hydrosulphuret. Hydrate of strontia contains 10 atoms of water, which agrees with the statements of Phillips and Noad* ; the baryta compound also contains 10 atoms. Sulphuret of calcium was prepared by heating the sulphate with charcoal; the mass when heated with water furnishes solely hydrosulphuret and hydrate of lime; the principal cause of this appears to lie in the insolubility of the hydrate. On boiling the solution of the hydrosulphuret in a retort, hydro- sulphuric acid is evolved and lime precipitated ; on further evaporation the solution assumes a yellow colour; a white powder, sulphite of lime, is often precipitated, formed from the hyposulphite produced by the boiling. In the concen- trated solution long' golden yellow crystals are formed, they are very small in quantity although large in volume. The crystals evolve no hydrosulphuric acid when treated with sul- phate of manganese, but only with acids, sulphur being sepa- rated ; treated with a large quantity of water they leave behind a quantity of lime. When heated they give off water and sulphur ; the residue treated with acid gives sulphur and hy- drosulphuric acid. The formula of this compound is Ca S5 + 5 Ca O + 20 aq. — (Pogg. Ann.^ vol. lv. pp. 415-437.) • See Phil. Mag., Third Series, vol. xi. p. 301.— Ed. Action of Water on Sulpkurets and haloid Salts. 287 In a second paper H. Rose takes into consideration the long-disputed point, whether the haloid salts and sulphurets decompose water when dissolved. Judging from analogy and the example of the sulphuret of barium, one would sup- pose that sulphuret of potassium would be decomposed with water into hydrosulphuret and caustic potassa ; the solution of this sulphuret turns red litmus paper blue ; and by its solu- tion in water heat is evolved, and we do not know that sul- phuret of potassium combines with water of crystallization. Rose concludes that the higher sulphurets are not decom- posed by water. The compounds of fluorine are so similar to those of sulphur that we might almost be justified in placing fluorine in a class with sulphur and not with chlorine ; it is possible that on dissolving fluoride of potassium in water, potassa and hydrofluoride are formed. Rose could not ob- tain them separate, but, as is well known, the solution reacts alkaline and also attacks glass. The fluoride of ammonium gives ammonia and hydrofluoride. Chlorides of potassium, sodium and ammonium produce a considerable degree of cold when dissolved in water, and hence we may conclude, that on the solution of these salts water is not decomposed. Chloride of calcium evolves heat when dissolved, and Thenard and Gay-Lussac adduced this to prove the decomposition of water, but it is simply a com- bination of the salt with water of crystallization. Chloride of sodium produces less cold than chloride of ammonium, but we know that under certain circumstances the former can combine with four atoms of water. The same is the case with several oxysalts. Rose has found that chlorides of antimony and bismuth evolve heat when dissolved, and supposes that they decompose water. As a general approximate rule we may say, that all compounds of bromine, chlorine, iodine, cyanogen and sul- phocyanogen with metals which are equivalent to the basic oxides, dissolve in water without decomposition, while those that represent the acid oxides decompose water. Fluoride of potassium evolves heat, but it combines with water ; the hy- drated salt may be obtained by gentle evaporation, or by adding alcohol to a solution of the fluoride ; it contains four atoms of water. — (Pogg. Ann., vol. lv. pp. 534, 557.) It is impossible to give any but an imperfect report of this most excellent paper in these notices without exceeding our limits ; we must most earnestly recommend the perusal of the original to all chemists. [ 288 ] XLIX. On the Occurrence of Shells and Corals in a Conglo- merate Bed, adherent to the face of the Trap Rocks of the Malvern Hills, and full of rounded and angular fragments of those rocks. By John Phillips, Esq., F.R.S., fyc. THE researches of Sir H. T. De la Beche during the autumn of 184<1 into the nature, antiquity and organic contents of the trappfean ash-beds of North Pembroke, coupled with other parallel inquiries, have excited in the minds of those persons who are attached to the Ordnance Geological Survey a lively interest in the study of the relations between trap rocks and the strata amongst which they appear. A very com- mon result of this study in South Wales is a conviction of the rarity of irruptive trap and the frequency of interstratified (and, in ordinary language, contemporaneous) beds of plu- tonic rocks and felspatho-hornblendic sediments, which are not always clearly distinguished from the fused rocks. On these points in the same or neighbouring districts, Professor Sedgwick and Mr. Murchison deliver nearly the same judg- ment. The great obligations which geology owes to Mr. Leonard Horner and to Mr. Murchison for their descriptions of the fused and sedimentary rocks in this chain, and of the grand movements in the crust of the earth, of which it is a noble monument, are universally admitted, but demand a glad ac- knowledgement from one who, following in their steps and profiting by their experience, desires to join to theirs the additional information which he may be so fortunate as to gather. After finishing the colouring of a great part of the Ord- nance map of this district, I turned to examine with care and interest the great problem which the Malvern hills present, viz. the determination of the circumstances under which the plu- tonic rocks were elevated. For this purpose the appearance of the fused and sedimentary rocks in every part of the Mal- vern chain and the surrounding country has been considered, separately and in combination ; and the general result is, that the elevation of these hills is a part of that grand series of associated movements, which the Director and other mem- bers of the Geological Survey have been tracing between St. Bride's Bay and the Severn, between the Teivy and the Bris- tol Channel. Viewed in this association, the geological epoch when the great movement of the Malvern rocks occurred, becomes de- terminable, and has in fact been determined by the eminent geologists already named. No one can witness the many On Shells and Corals in a Conglomerate at Malvern. 289 anticlinal and synclinal curvatures which on the western flank of the Malverns affect equally the Silurian and old red forma- tions, and then survey the comparatively horizontal and un- moved strata of new red marls and sandstones, which on the east and south touch indiscriminately the sienites, Caradoc sandstones, Wenlock limestone, and old red sandstone, with- out being satisfied that the great upward movement of the Malvern rocks happened in the interval between the old and the new red sandstones. But in what state were these plutonic masses raised ? as fused and liquid matter, or solidified rock? To determine this question, the observed positions of the strata which adjoin the trap range are important, but their condition and contents are still more essential. My first expectation, on looking gene- rally at the narrow continuous range of the Malverns, was, that here might be found an example of a gigantic sinuous mass, emitted in a liquid state along a portion of that great irregular fracture which is the western boundary of the new red sandstone, from the Severn to the Dee. The complicated nature of the trap, its innumerable vein-like segregations, its included gneissic beds, gave an additional interest to the ex- amination of the appearances at and near the junction of the trap with the exterior stratified masses. In aid of this inquiry I fortunately discovered two re- markable localities where Silurian strata of determinate age were in contact with the trap masses; one exposed in the deep cutting at the Wych, the other on the depressed sum- mit of drainage between the Hereford beacon and Swin- yard hill. Besides these are several examples of the sedi- mentary aggregates of the lower Silurian strata in juxtaposi- tion or actual contact with the trap rocks of the high Malvern ridge; with a detached series of low insulated ridges and bosses of trap on the western side near the southern extre- mity of the chain ; and with some low mounds described by Mr. Murchison at the northern extremity. The appearances connected with the low points at the northern end, and with a part of the ridge near the southern extremity, have been considered to indicate metamorphism in stratified rocks by heat*; and the phsenomena associated with the detached bosses and hillocks on the western side of the chain, may be believed to indicate irruption of trap amongst the lowest of the Silurian strata ; but generally along the chain itself, and especially in all the northern parts of it, there appears no evidence that the adjacent exterior strata have been invaded by liquid irruptive rock. * Murchison's Silurian System, p. 417 etaeq. Phil. Mag. S. 3. Vol. 21 . No. 1 38. Oct. 184-2. U 290 Mr. J. Phillips on a Fossiliferous Conglomerate. In the deep cutting at the Wych, sandstones and shales of the Caradoc formation are placed in a singular manner between masses of trap, but are entirely unchanged in aspect, and re- tain the usual organic remains. On the summit ridge near Swinyard hill, the upper beds of the Caradoc series, with the usual limestone bands and shales of that part of the Silurian strata, rest against solid felspathic trap on the south side and cover it as with a saddle. The corals and shells here gathered were in their usual state, and the strata appear unaltered. Contrasting these cases with others in the midst of the Malvern hills, where stratified rocks are irregularly mixed with the fused rocks, and have the character of gneiss, and with others on the western flanks where dykes and bosses of trap appear amongst peculiar sandstones and black shales, it ap- peared probable that some parts at least of the Malvern ridge were of higher antiquity than any of the exterior strata ; that amongst the lowest of these strata, local and limited irruptions of a different sort of trap had occurred ; but that the greater part of the Silurian strata visible in the northern parts of the hills had been subject to no peculiar heat emanating from the Malvern ridge. In this condition of the argument Mr. Murchison and Count Keyserling passed through Malvern and inspected the section of the Wych, as well as the north end of the Malverns, and Professor Sedgwick accompanied me on a leisurely survey of this and other points further south. On the day (Au- gust 1) while I was enjoying the advantage of his experience in examining the facts thus briefly adverted to, a discovery was made which threw a new and concentrated light on the phaenomena we were discussing. My sister, knowing the interest I felt in tracing out the hi- story of the stratification visible in these trap hills, sought dili- gently for organic remains in the midst of and on the western flanks of the sienitic masses of the North hill and Sugar-loaf hill. In this most unpromising search she was entirely suc- cessful, and collected from the midst of heaps of fallen stones, which seemed to be all trap, several masses richly charged with organic remains, and full of felspar, quartz, and horn- blende, in grains and large lumps. On careful examination, it was seen that those lumps were fragments, generally rolled to pebbles, and distributed with reference to one another and to the shells, just as quartz pebbles and chips are in a com- mon conglomerate. It was, in fact, certainly and evidently a conglomerate full of Silurian shells, and pebbles and frag- ments of the sienitic, felspatho-quartzose and other rock- masses of the Malvern hills. adherent to the Trap of the Malvern Hills. 291 The next thing to determine was the position of this con- glomerate in relation to the ridge of sienitic rocks amongst the detritus of which its fragments lay. This was difficult. We.t. East. 12 The abundance of detritus on all the slopes is so great as to conceal for the most part the junction of the stratified and unstratified rocks. The loose shelly pieces we found abun- dantly for fully one-third of a mile along the mountain side, and at length the conglomerate rock itself was plainly seen ad- hering to the extreme western nearly vertical face of the trap mass, west of the Worcestershire beacon, in a situation con- tiguous to a large excavation of the lower Caradoc sandstone. These facts ascertained, I waited for the arrival of Sir H. T. De la Beche at Malvern, to have the shelly bed thoroughly explored, and its contact with the trap rocks carefully traced. We found the surface of the trap nearly vertical, but undu- lating and irregular, and its strike nearly north and south ; the rock is here hornblendic, dark green or purplish in co- lour, and, as usual in all these hills, it is within short distances mixed and variegated with more felspathic portions, felspatho- quartzose veins, &c. Closely adhering to it was usually a softish laminated clay ; bedded in the clay, or touching the trap rock, were multitudes of rolled pebbles and angular chips and fragments of stone, accumulated in an irregular bed above U 2 292 On Shells and Corah in a Conglomerate at Malvern. a foot or only a few inches in thickness against the trap. In the intervals of these pebbles were partial admixtures of ar- gillaceous shale, abundance of shells, and smaller chips and fragments of stone, more or less stained brown, in the same manner as commonly happens in shelly cavities in other con- glomerates and sandstones far removed from the trap. Ex- terior to this very pebbly mass, the shells were equally nume- rous, but the rock fragments amongst which they lay were generally angular, appearing just as if they had fallen from a cliff upon a pebbly beach, and received into their interstices abundance of shells and sand drifted by the water. The degree ofjirmness of the shelly masses thus examined in situ, is less on an average than that of the loose pieces on the hill slopes which were first observed ; these latter being the hardest portions which best withstood destroying agencies. The shells, corals and encrinites, are commonly represented by casts and moulds, but a few specimens have occurred of Turbinolopsis, with the calcareous substance entirely pre- served. The pebbles and fragments of stone mixed with the shells are of the same nature as the rocks immediately adjacent and composing the neighbouring hills; that is to say, characteristic compounds and segregations of hornblende, felspar, quartz, and mica, in great variety. The whole mass is stained by fer- ruginous admixtures, and at a small distance looks like some of the dark trap of the hills with which it is in contact. What may be its degree of induration at a considerable depth is unknown, the situation allowing only of an exploration to the depth of a few feet. The just inference from the occurrence of the shelly con- glomerate thus briefly described, appears to be that the sie- nitic and other associated rocks of the northern portion of the Malvern hills were accumulated and indurated previous to the aggregation of the lower portions of the Caradoc sand- stone series; and that they were, with the whole Silurian series, raised in a solid state. In harmony with this conclusion, is the abundance of frag- ments and disintegrated grains of the Malvern rocks in other conglomerates (not shelly) of the Caradoc series, about the north end of the chain, examined by Sir H. T. De la Beche and myself. Even in Ankerdine hill, eight miles north of Malvern, fragments of the sienitic rocks were observed in the Caradoc sandstone by Capt. James, R.E., and myself; and the conglomerate of May hill yielded similar results to Sir H. T. De la Beche. Observations of this nature, combined with accurate sur- Prof. MacCullagh on the Dispersion of Optic Axes, tyc. 293 veys of the great lines of subterranean movement, may here- after enlarge the limited view now presented of a part of the Malvern hills, into a general contemplation of the agency of heat during the Palaeozoic periods in the great physical re- gion between the vale of the Severn and the coasts of Wales. But to state such a speculation without the data which have been collected for its illustration, would be useless or injuri- ous, and the constitution of even the Malvern chain itself is sufficiently varied in its different parts, to induce a long pause before the apparently proved high antiquity of the northern sienites should be implicitly extended even to the southern portion of the same chain. Malvern, Sept, 19, 1842. L. On the Dispersion of the Optic Axes, and of the Axes of Elasticity, in Biaxal Crystals. By James MacCullagh, LL.D., M.R.I.A., Fellow of Trinity College, and Professor of Mathematics in the University of Dublin*. TN the last Number of the Philosophical Magazine (p. 228), -■- there appeared an extract from the Proceedings of the Royal Irish Academy, containing a notice of a memoir which I had the honour of reading to that body on the 24th of May, 1841 ; and in the concluding paragraph of the notice a brief allusion is made to a K mathematical hypothesis" by which I had con- nected the laws of dispersion and those of the elliptic polari- zation of rock-crystal with the other laws that were there an- nounced. My present object is to indicate the development of that hypothesis, with reference more particularly to the subject of dispersion in crystals, and to communicate a very simple result which I have lately had occasion to obtain from it. The result is remarkable as embracing and explaining a class of intricate phaenomena which hitherto have not been connected with any theory, or rather have stood in opposition to all theories ; I mean the phaenomena of the dispersion of the optic axes, and of the axes of elasticity (as they are called) in biaxal crystals. The name of axes of elasticity was given by Fresnel to three rectangular directions, which, according to his theory, exist in every crystallized medium, and which are distinguished by the property, that if a particle of the medium be slightly displaced in the direction of any one of them, the elastic force thereby called into play will act precisely in the line of the displace- . * Communicated by the Author. 294 Prof. MacCullagh on the Dispersion of the Optic Axes, nient. These directions coincide with the axes of the ellipsoid by which he constructs his wave-surface ; and the position of the axes being thus fixed, it is only their lengths that can be supposed to vary for the differently coloured rays. Such is the view taken by Fresnel with regard to crystalline dispersion, and it is obviously the only view that his theory admits. Suc- ceeding theorists, in their numerous attempts to deduce Fresnel's beautiful laws from dynamical principles, have al- ways been obliged to assume that the medium is symmetrically arranged with respect to three rectangular planes ; and as, in this hypothesis, the axes of elasticity, or of optical symmetry, necessarily coincide with those of symmetrical arrangement, their directions are fixed, as before, independently of colour. From these principles it follows that the optic axes for dif- ferent colours all lie in the same plane, namely, the plane of the greatest and least axes of the ellipsoid, and that they are equally inclined to each of the latter axes, so that the angle made by any pair, to whatever colour they belong, is always bisected by the same right line. This was accordingly, for a long time, believed to be the case ; and the earlier experi- ments of Sir J. Herschel (Phil. Trans. 1820) which are ap- pealed to by Fresnel, as well as the observations of Sir David Brewster, seemed to establish it as a general law. But it was afterwards discovered by Sir J. Herschel, that, in borax, the optic axes for different colours lie in different planes inclined at very sensible angles to each other ; and the same discovery was made about the same time (1832) by M. Norrenberg. The latter observer further ascertained, that even when the optic axes all lie in the same plane, there are cases, as in sul- phate of lime, wherein their angles are not bisected by the same right line. These facts, and others of a like nature that have been since observed, show the falsehood of the suppo- sition that the lines called the axes of elasticity have always the same directions whatever be the colour of the light; they are inconsistent with all received notions, and contradict every theory that has been hitherto proposed. No person, as far as I am aware, has even attempted to explain them. But in the theory which I have constructed to represent the laws of the action of crystallized bodies upon light, and which has already brought so much within its grasp, the phenomena in question do not offer any difficulty whatever; on the contrary, they are of a kind that would naturally be looked for, antecedently to experiment. For in this theory, I make no hypothesis as to the constitution of the sether, or the arrangement of its molecules ; nor any hypothesis, like and of the Axes of Elasticity, in Biaxal Crystals. 295 that of Fresnel, respecting the mechanical signification of the axes of elasticity. The existence of three rectangular axes possessing peculiar properties is not a principle, but a result, of theory ; their directions are determined by conditions per- fectly analogous to those which determine the principal axes of an ellipsoid from its general equation ; and these directions are functions of certain quantities which are constant when differentials of the second and subsequent orders are neg- lected, but which vary when these are taken into account. The differentials of higher orders introduce terms depending on the wave-length ; and thus the directions, as well as the lengths, of the principal lines depend on the colour of the light, or, to speak more accurately, on the length of the wave. All this will be easily understood if we recur to the first principles of the theory. According to these, everything de- pends on the form assigned to the function V in the general dynamical equation Jffi^d^i+d^+d^n)=fffd^yMy, from which the motion of the aether is deduced. In my first memoir on the subject (read to the Academy on the 9th of December, 1839), I showed that when differentials of the first order only are preserved, the function V — which may perhaps with propriety be called the potential, since the mo- tion of the system is potentially, or virtually, included in it — is a function of the second degree, composed of the three quantities X, Y, Z, which are connected with the displace- ments £, ij, f by the following relations : — x_d_>?__£?jr y=— — — Z — ~ — — ~~ dz dy9 ~ dx dz ~ dy dx' To show this, I make use simply of the consideration that the motion must be such as to satisfy the condition d% dr) d£ „ dx dy dz ' which seems to be characteristic of the vibrations of light. But the same condition allows us to suppose that the poten- tial contains not only the quantities X, Y, Z, but their dif- ferential coefficients of any order with respect to the coordi- nates. This supposition, however, is too general, and re- quires to be limited by other considerations. Now the most natural restriction which can be imposed consists in the as- sumption that the quantities of all orders are formed on the same type, those of any order being derived from the prece- 296 Prof. MacCullagh on the Dispersion of Optic Axes, Sf-c. ding in the same way that the quantities X, Y, Z are derived from £, >j, £; there are particular reasons also which go to strengthen this hypothesis, and have led me to adopt it. Putting therefore X-^_^? V _ rL? _ ^5 7_ 1_ dx dz' x~ dy dx' X rfY, dZl __dZl_dX1 _dXl dY} 2 d ,? rfz/' 2 d .r dz* 2 */ y d .r ' and so on, I suppose the potential to be a function of the se- cond degree, composed of all the quantities X, Y, Z, X1} Y15 Z1S X2, Y2, Z2, &c; and this is the "mathematical hypothe- sis " alluded to in the beginning of this article. The hypo- thesis occurred to me more than three years ago (June 1839), but I did not venture to communicate it to the Academy until the date of my second memoir (May 1841); and even then I had not studied it with the attention which I now conceive it merits. It was only very lately, in fact, in some conversations which I had with M. Babinet during a short visit to Paris, that my attention was strongly drawn to the subject of disper- sion in crystals, particularly the dispersion of the axes of elasticity. My thoughts then naturally reverted to the hy- pothesis which I have mentioned, and since my return I have found that it affords a complete explanation of all the phae- nomena *. I have also found that it gives the general law, extended to biaxal crystals, of that elliptic and circular polarization which has hitherto been detected only in quartz and in certain fluids; while for the case of rectilinear polarization it gives a law (very possibly a true one) more general than that of Fresnel, but quite as elegant, and differing very slightly from it. The hypothesis, therefore, is still too general for our present purpose. To make it include only those crystals to which the law of Fresnel is rigorously applicable, the alter- nate derivatives X15 Yv Zj, X3, Y3, Z3, &c. must be supposed to vanish in the function which represents the potential. Then, the axes of coordinates having any fixed directions within the crystal, the axes of elasticity will be the principal axes of an ellipsoid represented by an equation of the form AxZ+ByZ + CzZ+ZDijz+ZExz + 2Fxy = 1, * I am indebted, for my information on the subject, to a short article, drawn up by MM. Quetelet and Babinet, in the 'Bulletin of the Royal Academy of Brussels, vol. ii. p. 150; as also to PcggendorfTs Annals, vol.xxvi. p. 309 ; vol. xxxv. p. 81. Mr. G. G. Stokes on the 'Rectilinear Motion of Fluids. 297 in which each of the six coefficients, the first, for example, ex- presses a series of the form K*$+% +■$ + *« where X denotes the wave-length, and all the other quantities are constant. The ellipsoid itself is the reciprocal of that ellipsoid by which the wave-surface is constructed, and its semiaxes are the three principal indices of refraction. As X is supposed to vary, not only the length but the direction of the principal axes vary, and thus we have a different wave- surface for every different wave-length within the crystal. The optic axes are perpendicular to the circular sections of the above ellipsoid, and describe, in general, two fragments of a cone, the equation of which may be found by supposing A to be variable in the equation of the ellipsoid. But only very particular cases have been hitherto observed, and I shall not stop to discuss them. Trinity College, Dublin, J. MacCullagh. September 1842. LI. Remarks on a paper by Professor Challis, " On the analytical Condition of the Rectilinear Motion of Fluids." By G. G. Stokes, B.A., Fellow of Pembroke College, Cam- bridge*. TN the August Number of this Magazine (p. 101), Professor *■ Challis has written an article, of which the object is to prove that, in all cases of fluid motion in which udx + vdy + wdz is an exact differential, the motion is rectilinear. The importance of this question may apologize for these remarks, since, if the reasoning in that article be correct, it will affect the validity of much that has been written on the subject. It appears to me however that Professor Challis has made an assumption which is not allowable, and consequently the con- clusion founded on it is not allowable either. In what fol- lows, I shall call the path of a particle of fluid in space a line of motion, and a line traced at a given instant from point to point in the direction of the motion a line of direction. As the basis of his reasoning Professor Challis assumes, that in every case where the continuity of the fluid is main- tained, the most general supposition that can be made re- specting the directions of motion in each indefinitely small element of the fluid is, that they are normals to a surface of continuous curvature, and as such pass ultimately through * Communicated by the Author. 298 Mr. G. G. Stokes on the Rectilinear Motion two focal lines ; that is to say, that the above is true neglecting quantities of the order P p2t P and p being any two points in the element ; that this is the meaning is shown by the fact that the whole investigation depends on quantities of the order Pj9. Now, not only in the case where udx + v d y + w d z is an exact differential, but also in the case where it is integrable by a factor, there exists a surface of displacement passing through P, and the above statement will be true for an ele- ment of this surface. But it will not generally be true for an element of three dimensions; for, let p be taken in the line of direction passing through P ; then, if «x be the radius of ab- solute curvature of this line at the point P, and Pp = 8 s, the angle between the tangents at P and p will be ultimately 8 s — . Neglecting quantities of the order 8 s9, a line PT' drawn w through P parallel to the tangent at P may be taken instead of the tangent at p. Now, even if we suppose the line P T' to pass through the focal line which is at a distance r from p, the least distance between it and the other focal line, which 8s is at a distance r1 from p, will be ultimately r' — . Hence, it cannot ultimately pass through both focal lines, unless "ro- be at every point infinite, i. e. unless all the lines of motion be right lines, which is evidently a very limited case. Conse- quently, it is only in this case that it is proved that surfaces of displacement are surfaces of equal velocity. There is another part of Professor Challis's reasoning with which I cannot agree. It is that d (-rr) or , , , dx ■ \dt J dtdx d*$ 7 d?4> , L . . c + — — ►*- dy + , , d n — 0, in passing from one point to another of a surface of displacement. For, d ( — \ m 0 the differential equation to a family of surfaces whose general equation is — j— = C, which family of surfaces is in general quite different from that whose equation is

dy, dz should be taken along that surface of the second family which passes through the point {x,y, z), whereas the variations for which d( — ) = 0, must be taken along that surface of the first family which passes through the same point. If

9). S6 LII. On Conchyliometry. By the Rev. H. Moseley, M.A., F.R.S., Professor of Natural Philosophy and Astronomy in King's College, London. To the Editors of the Philosophical Magazine and Journal. Gentlemen, TN a paper printed in the Transactions of the Royal Society ■*■ (1838, part ii.*) I have investigated certain properties of the spiral curves traced upon the surfaces of shells (concho- spiralsf) common to them and to the well-known logarithmic spiral. The results deduced from my admeasurements have since been confirmed by those of Professor Naumann of Freiberg (PoggendorfF's Journal, 1840), who has developed, by an in- dependent investigation, several new properties of these curves, and determined with his accustomed accuracy, in respect to an extensive series of Conchylia, the particular value of the constant angle according to which each traces its concho- spiral. With a view to a further development of the geometrical properties of shells, I have in my paper, above referred to, investigated certain formulae representing the equation to the concho-spiral, the volume of a conchoidal solid, the position of its centre of gravity, and the area of a conchoidal surface. In the inclosed paper I have continued these researches in respect to concho-spirals and conchoidal surfaces, and in some particulars corrected them. King's College, London, Yours, &C, July 20, 1842. Henry Moseley. I. The Polar Equation to a Concho-spiral. Let a logarithmic spiral, whose polar equation is R = R0 ge cot A^ ke conceived to be wrapped upon a cone the angle at [* An abstract of Prof. Moseley's paper here referred to was given in Phil. Mag. S. 3. vol. xiii.p. 464.] f I have adopted the nomenclature of Prof. Naumann. The Rev. H. Moseley on Conchyliometry . 301 whose apex is 2 , the pole of the spiral coinciding with the apex of the cone. The circular arc 8, whose radius is unity when developed, will when wrapped upon the cone, become a cir- cular arc 0, whose radius is sin i, .*. 8 = 0 sin t, whence it follows that R representing the distance of any point in the spiral from the apex of the cone, and 0 the angle included between two planes, intersecting in the axis of the cone, one passing through that point of the spiral, and the other through the point where R = R0, we have R = R0 s<>sin'cotA. Let Ri R2 R3, &c. be distances from the apex of the cone of points of the spiral in the same straight line passing through the apex, .-. Rx = R0 e 6 sin / cot A R2 = R0 s (4+2 ->t) sin i cot A R3 = R0 g (4+4 Q representing the quotient of any two consecutive distances between the whorls measured on the same straight line passing through the apex. On the supposition made therefore, viz. that a plane lo- garithmic spiral is wrapped upon a cone, its pole coinciding with the apex of the cone, it follows that the distances of the successive whorls of the spiral measured on the same straight line passing through the apex of the cone, are in geometrical progression ; and conversely. Now in shells they are found, by admeasurement, thus to be in geometrical progression. The spirals described on shells, and called concho-spirals, are therefore such as would result from winding plane logarithmic spirals on cones. To determine in respect to any shell the constant angle A which the tangent to its concho-spiral when developed makes with its radius vector, let it be observed that logs Q = 2 7T sin » cot A . 2 7rsin i ,. . .•. tan A = -j p^, (1.) log, Q where A is the angle required. S02 The Rev. H. Moseley on Conchyliometry. Now the quotient Q is the same for all the spirals described on the surface of the same shell ; if then we represent logs Q , * bye, 2 7T * we have sin i cot A = — ° = c, 2 7T and R = n0Bc° (2.) which is the general equation to a concho- spiral. Since each of the concho-spirals on any shell must have its origin in a corresponding point of the generating curve of that shell when in its initial position, and since the initial dimensions of the generating curve of every such shell are ex- ceedingly (perhaps infinitely) small, it follows that all such spirals have their origins very nearly (perhaps accurately) in the same point, and therefore that the conical surfaces on which they are severally described have their apices in the same point* ; the value of R0 being the distance from the com- mon apex to that particular point of the generating curve, at which the spiral intersects it, in that position in which 0 is assumed to be zero. II. To determine the inclination u of the tangent at any point of a concho-spiral to a line drawn from that point parallel to the axis of the shell. Let P Q represent any portion of a concho-spiral, P H a tangent to it at P, P L a line drawn from P parallel to the axis I R of the shell, I the apex of the cone on which the concho-spiral is described. Join I P, then is I P H a con- stant angle represented by A, and H P L (represented by «) is the angle required. Describe a sphere with radius unity from the centre P, and let a ?, a b, b e be the intersection of the planes I P L, I P H, L P H with its surface. The spherical angle bae is a right * It is a law common to all surfaces of revolution whose generating curves varying their dimensions remain always geometrically similar, that the spiral lines described by given points in these curves lie all on the sur- faces of cones having a common apex. The Rev. H. Moseley on Conchyliometry. 303 angle, since the plane I P H is a tangent to the cone, and IPL passes through its axis, .•. cos b e = cos a e . cos a b. Now£<> = LPH = «,fle=LPI = RIP=, fl6 = IPH = A, .*. cos a s= cos i . cos A (3.) .*. i + tan2 « = sec2 a = 5 s-r qosz i cosa A 2 1— cos2 » cos2 A _ sin2 A + sin2 < cos2 A cos2 1 cos2 A cos2 < cos2 A tan2A cos* * a tan2 1 o 1 + tan2i= - A . o +tan2t=^ 3 . +1 Uan\ cot2 A sin2 » [ cor A sin2 1 ^ Now cot A sin 1 = — Jp — (equation 1.), " = {1+(isir§)Ttan (*J 2* r. / 2 .•. tan Similarly, it may be shown that sin in--{l+(^.)'}*rinA (5.) III. The Area of a Conclwidal Surface. Let R P S represent any position of the generating curve, and QPm a portion of one of the spiral lines generated by any point P in it. Let I represent the apex of the cone on whose surface the spiral P Q is described. Join P I and draw P H a tangent to the spiral, and P T a tangent to the generating curve in P. Imagine a sphere described with radius unity from the centre P, and let a b, be, ac repre- sent the intersections of the planes H P I, H P T, and I P T with its surface. Now the plane H P I, being a tangent to the cone at P, is perpendicular to the plane RIP which passes through its axis I R S ; the spherical angle b a c is therefore a right angle. Moreover, the angle I P Q made by a tangent to the spiral with the line I P drawn from the summit of the cone is, in the 304< The Rev. H. Moseley on Conchyliometry. case of shells, a constant angle, represented by A, and the angle P I R, being half the angle at the apex of the cone, is also a constant angle in respect to that spiral, represented by *. The angle P T R made by a tangent to the generating curve at P with the axis of the cone is constant for the different positions of the same point P on the generating curve, as the curve varies its -position by the variation of 0, but variable for different points on the generating curve, in any given position of that curve ; let it be represented by <$>.

— • i) .*. sin H P T = V 1 — cos2 A . cos2 (— i) .-. area P V = v' 1-cos2 A cos2 ( - i) . As.AS. Now the whole surface is made up of elements similar to P V* therefore passing to the limit and integrating, whole surface =Jj \/ x _ coss A C0g2 ^ _ ^ # dsdS - /TV 1 -cos2A cos2 ($-i) . ~ dQ ds, (6.) which is a general expression for the area of a surface of re- volution, whose generating curve, varying its dimensions, remains always similar to itself. In the case of shells, if the surface of the cone on which The Rev. H. Moseley on Conchyliometry. 305 the spiral P Q is described be developed, this spiral will be- come a plane logarithmic spiral, whose polar equation has been shown to be R = R0 g e cot A where 0 — 0 sin i Now sin i cot A = — -^ — •= c 2 7T dS dS dO t> • a ci .'. — — - ss — — . — - — = Rn sin » cosec Aec dd de dS ° .\ con. surf. = / / R0 sin i cosec A { 1 — cos2 A cos2 ($ — «)} ^o6edHs. Now sin t cosec A { 1 — cos2 A cos2 (

-,)"| V' — ») r d s0 (7.) where the integral / R0-< sin2 i + c2 sin2 (

rfs0 re- presents a constant determined by the geometrical form of the generating curve, and its dimensions when 0=0. [The general form of the expression agrees with that given in equation 15, p. 368 of a paper on the geometrical pro- perties of turbinated and discoid Shells in the Phil. Trans., part ii. 1838.] Phil. Mas. S. 3. Vol. 21. No. 138. Oct. 1842. X [ 306 ] LI 1 1. Proceedings qf Learned Societies. GEOLOGICAL SOCIETY. [Continued from p. 150. J Nov. 17, A LETTER addressed to Dr. Fitton, by Mr. Lyell, and 1841. **- dated Boston the 15th of October, 1841, was read. Mr. Lyell's attention, between the period of his arrival in the United States and the date of his letter, had been principally devoted to the grand succession of Silurian, Devonian, and Carboniferous strata in the state of New York and on the borders of Pennsylvania, having been accompanied during a portion of his tour by the States' Geologist, Mr. J. Hall ; but he had also visited, in company with that gentleman, the Falls of Niagara and the adjacent district, and he states, that he purposes to communicate a paper on the phenomena of the recession, drawn from new arguments, founded on the position of a fluviatile deposit below the Cataract. He expresses his intention of also communicating a notice of five localities of Mastodon bones which he had visited, digging up some remains himself, and collecting the accompanying shells, which he says, seem to have been neglected. He had likewise examined, accompanied by Prof. Silliman and his son, the new red, with intrusive trap, in Connecticut ; and, assisted by Mr. Conrad, he had collected fossils in every member of the cretaceous system in New Jersey *. The principal object, however, of the present communication is, to point out the extension to the United States of Mr. Logan's generalizations on the beds of fire-clay containing Stig- maria, formerly laid before the Society in a paper on the coal-field of South Walesf. Mr. Lyell had met Mr. Logan at New York, pre- viously to that gentleman's visit to the anthracite coal-field of Penn- sylvania, and he adverts to the delight which Mr. Logan must have felt in witnessing the occurrence of beds of Stigmaria fire-clay to an extent far exceeding what could have been expected. On the con- fines of the states of New York and Pennsylvania, Mr. Lyell found remains of Holoptychius and other fishes in the old red sandstone, and at the bottom of the overlying coal series a thick quartzose conglomerate ; and he says that the coal-measures, with their im- bedded plants, bear an exact analogy to British coal-measures, both in detail and as a whole. In investigating the coal district of Bloss- berg, Mr. Lyell had for a guide Dr. Saynisch, president of the mines. The first point which they examined presented three seams of bitu- minous coal resting on fire-clay containing Stigmariae, with the leaves attached to the stems, and extending in all directions through the clay ; and they observed, in a gallery lighted on purpose, that the stems seen in situ were very nearly all parallel to the planes of stra- * Mr. Lyell mentions incidentally having observed between Easton and Trenton, on the Delaware, and in 40° of north latitude, that all the trees were barked on one side, at the height of twenty-two feet above the present level of the river, owing to a freshet and stoppage by ice in the spring of 1841. The stuccoed parts of the houses were also strangely scraped ; and in one place the canal, the towing-path of which is twenty-two feet above the river, was so filled with gravel that carriages did not cross by the bridges. [f See Phil. Mag., S. .'5., vol. xviii. p. 217; vol. xx. p. 430.] Geological Society. 307 tification, only one being in an oblique position. Every stratum underlying a coal-seam examined by Mr. Lyell, presented the same phenomena, except one, and in that case the bed was so sandy that it could not be considered as a fire-clay. The thickness of these Stigmaria deposits varied from one foot to six feet. The roof of the Blossberg coal-seams consists usually of bituminous slates, but occa- sionally of very micaceous grit, and it contains great varieties of ferns, as well as other plants, agreeing, generically at least, with those common in the British coal-measures. Mr. Lyell next examined the anthracitic coal-district at Pottsville, on the Schuylkill, in the southern part of the Alleghanies. This district had been examined and described, as well as modelled, by Mr. R. C. Taylor, and the model had been inspected by Mr. Lyell previously to his visit. The whole of Pennsylvania has been mapped by Prof. H. D. Rogers, by direction of the State Legislature. Mr. Lyell refers to this survey, and he states that, by consulting Prof. Rogers's map, it will be found that the Alleghanies, or more properly the Appalachians, which, viewed geologically, are 120 miles broad, consist of twelve or more great parallel ridges, or anticlinal and syn- clinal flexures, having a general north-north-east and south-south- west strike, but in Pennsylvania a nearly east and west strike prevails. The strata are most tilted on the southern border of the chain, where their position is often inverted, and the folds become less and less towards the central ridges and troughs, which again increase in breadth the more northward their position, till at last the beds are almost horizontal. The oldest formations also are chiefly exposed in the most southern or disturbed regions, where syenite and other plutonic rocks are intruded into the lower part of the Silurian series. It has long been observed, that the anthracitic coal is confined to the southern or Atlantic side of this assemblage of small parallel chains, and that the bituminous occurs in the more inland or less disturbed region ; the conclusion, therefore, Mr. Lyell states, seems inevitable, that the change in the condition of the coal was a concomitant of the folding and upheaval of the rocks. The conversion, moreover, is most complete where the beds have been most disturbed ; and there are tracts in Pennsylvania and Virginia, near the centre of the chain, where the coal is in a semi-bituminous state. Chemical analysis, likewise, has shown that a gradation from the most bituminous to the most anthracitic coal may be found in crossing the chain from north to south*. The associated shales, &c, of the disturbed regions exhibit no alterations. It has also been supposed that the anthracite belonged to the trans- ition, and the bituminous coal to the secondary period ; but this be- lief, Mr. Lyell says, has been gradually abandoned, as the knowledge of the geological position and the fossil plants of the coal- districts have become better known. Both the anthracitic and the bituminous coal overlie the old red sandstone, and contain the same ferns, Si- gillarise, Stigmariae, Asterophyllites, &c. ; and they are as abundant and perfect in the anthracite as in the bituminous coal. * See papers by Prof. fj. D. Rogers, Dr. Silliman, &c. X2 308 Geological Society : — Mr. Lyell on the At the first point where Mr. Lyell, accompanied by Prof. Rogers, examined the Pottsville coal-measures, the strata are nearly vertical, being cut off by a great fault from the less inclined beds which form the northern prolongation of the measures. They present thirteen beds of anthracite, the lowest of which alternate with the uppermost strata of the coarse underlying conglomerate. The southern wall of an excavation from which the coal had been re- moved, and which wall occupied the place of the underclay, pre- sented impressions of the stems and leaves of Stigmaria; and on the more solid and slaty beds of the opposite wall, or original roof, there were leaves of Pecopteris, reed-like impressions, and Calamites. In the slightly inclined northern continuation of the coal-measures, Mr. Lyell observed in the Peachmount vein, three miles north-east of Pottsville, a bed of anthracite eight feet thick, overlaid by the usual roof of grey grit, and underlaid by blue clay or shale with Stigmaria?. Impressions of ferns were likewise noticed in the coal itself. Only one instance was met with in the Pottsville coal-district, by Mr. Lyell and Prof. Rogers, of a Stigmaria, placed at right angles to the plane of stratification. The Pottsville, or southern anthracitic coal-field of Pennsylvania was illustrated by a section resulting from the former labours of Prof. Rogers, under whose guidance Mr. Lyell examined the coun- try. The following remarks may explain the general structure of the country ; the names applied to the formations are not, however, those previously employed by the American geologists, but those suggested by Mr. Lyell, in conformity with the conclusions at which he arrived after his tour in New York, and a comparison of the strata of that state with their British equivalents. The contrast between the relative importance of most of the Silurian and Devonian groups in Pennsylvania and in New York, Mr. Lyell states, is very great, arising from a larger portion of sandstones and grits in the Pennsylvanian rocks. The section extends from north of Pottsville to the country ranging immediately south of Orwigsburg. To the south of the vertical coal-measures and the subjacent conglomerate there are displayed successively — 1st, a vast series, composed of red shales 3000 feet thick, of grey sandstone 2400 feet thick, and of red sand- stone 6000 feet thick, the whole being considered by Mr. Lyell as portions of the old red sandstone ; and 2nd, of olive-coloured shale containing Devonian fossils. The dip of the strata is either nearly vertical or inverted. Still further south, and a short distance north of Orwigsburg, the olive-coloured shales are succeeded by very highly inclined or inverted beds of upper Silurian rocks flanking a protruded band of lower Silurian strata ; and lastly, on the southern confines of the section is a trough of the Devonian olive- coloured shales resting on the upper Silurian strata. Beautiful exhibitions of the underclay with its associated plant, and of the overlying roof with its distinct remains, were observed by Mr. Lyell and Prof. Rogers at Tamaqua, in the southern coal-field. The thinning out of the grits and conglomerates of the west causes the beds of anthracite to be brought more nearly together in this Stigmaria-Clay in the Coal-Jield of Pennsylvania. 309 district ; and Mr. Lyell says, the decrease in the thickness of the in- tervening strata prepares the observer for the union of several of the seams still farther east, and for the enormous thickness of the anthra- cite at various places near the village of Mauch Chunk, or Bear Mount, particularly at the well-known Lehigh-Summit Mines. At this point a mass of anthracite forty feet thick, deducting three in- tercalated fire-clays and a fine thin vein of impure coal, is quarried in open day, a covering of forty feet of sandstone being entirely re- moved. In the south mine, where there is a sharp anticlinal fold in the coal, the Stigmaria-clay, four feet thick, was well seen, with nearly forty feet of coal above it and four below. In the Great mine Mr. Lyell observed the following section : — Top, yellow quartzose grit. Coal, two or three inches of the uppermost part of the bed being in the state of dust, as if they had been crushed or rubbed by the yellow quartzose grit 5 feet. Blue fire-clay with Stigmariae 15 inches. Coal, including two or three seams of an impure slaty nature 25 feet. Blue fire-clay with Stigmariae 2 feet. Coal, with an intervening layer of hard, bituminous slate 8 feet. The anthracite, as in other parts of these coal-measures, often exhibits a texture exactly like that of charcoal ; and frequently im- pressions of striated leaves, exactly resembling, as pointed out by Prof. Rogers, those of liliaceous plants, particularly the iris. Mr. Lyell, accompanied by Prof. Rogers, afterwards examined the Room Run mines, on the Nesquahoning, where he saw a splendid exhibition of Stigmariae in a bottom clay, one stem, about three inches in diameter, being no less than thirty-five feet in length. In the roof of slaty sandstone were impressions of Pecopteris, Glos- sopteris, and other ferns. At Beaver Meadow, or the middle coal-field, a bed of anthracite is overlaid as well as underlaid by Stigmaria blue clay ; the upper fire- clay, however, soon thins out, and is replaced by sandstone. No coal rested upon it, but Mr. Lyell observes that the carpeting of coal may not be always large enough to cover the flooring of fire-clay, or some change of circumstances or denudation may have interfered with the usual mode of deposition. Upon the whole, Mr. Lyell says, the accumulation of mud and Stigmariae was, in Pennsyl- vania as in South Wales, the invariable forerunner of the circum- stances attending the production of the coal-seams. The two ex- treme points at which he observed the Stigmaria-clay, Blossberg and Pottsville, are about 120 miles apart in a straight line, and the ana- logy of all the phaenomena at those places, and still more on both sides of the Atlantic, is, he says, truly astonishing. In conclusion, Mr. Lyell states, that he had just received a letter from Mr. Logan, announcing the existence of the bottom clay, with Stigmariae, in Nova Scotia ; and that Mr. Logan had visited Mauch Chunk. 310 London Electrical Society. LONDON ELECTRICAL SOCIETY. [Continued from p. 64.] July 19*. — The Society assembled for the first time in its new apartments in Cavendish Square. The following papers were read : — 1 . " On the Solution of Gold in Muriatic Acid by Voltaic Agency." By H. Prater, Esq., Memb. 2. " On the Action of Lightning Conductors." By Mr. Charles V. Walker, Hon. Sec. Having introduced the subject by referring to his observations on the lightning-flash at Brixton Church (vide Phil. Mag. for July, p. 63.), the author states that a series of recent experiments have rather tended to confirm than change his opinion upon the phenomena termed often "lateral discharge;" and that his present object is to direct the attention of the Society to certain facts, which have not been so prominently regarded as their nature demands ; and here especial allusion is made to the Leyden discharge. That this dis- charge is often employed in illustrating the action of lightning is manifest to all who have paid any attention to the matter, and that a large portion of the experiments, which have given rise to so much difference of opinion, are the effects of Leyden discharges, is like- wise well known. Mr. Walker commences by endeavouring to show the difference between such discharge and a flash of lightning : he states, that sup- posing a cloud to resemble one coating of a jar, the air to corre- spond with the glass, and the earth with the other coating, the discharge of that cloud is directly between the coatings, viz. through the insulator ; and he then shows that a Leyden discharge only re- sembles this, when it is of force sufficient to perforate the glass. He explains that the regular discharge is operated upon by two forces acting counter to each other ; the one directly between the two coatings in direction a, the other between the discharging balls in a direction b ; and that the length of shock, or as it is termed striking distance, is the difference between these forces : when a — b represent the resultant, the glass is perforated ; when b— a is the equivalent, the regular discharge occurs. That this explanation is not imaginary, is shown by comparing the striking distance of the Leyden discharge with that from the prime conductor. With the Polytechnic battery, containing 70 feet of coated glass, the distance is about one inch, while from the large conductor of the machine sparks upwards of two feet long will appear. He then calls into requisition the ocular illustration of difference ; when one spark is direct and compact, the other is long and zigzag ; and this leads him to point out the re- semblance between lightning flashes and sparks from the conduct- or ; not merely in their visible and accidental characters, but in their passing just as lightning does, directly from a charged body to- wards the earth in the direction of least resistance. Having shown * The papers read before the Society in April, omitted to be noticed in our last, will be found in the Proceedings, Part V. Mr. C. V. Walker on Lightning Conductors. 311 his reasons for excluding Leyden jars from this inquiry, and glanced at the importance of establishing such a position, he proceeds to throw sparks from the machine into wires arranged to represent lightning rods, and makes his observations upon the effects produced by these wires. Some of them pass perpendicularly between the con- ductor and the earth, others are led off horizontally : all give rises to the said " lateral spark." The next point was to show that these wires did resemble lightning-rods ; and for this purpose an arrangement was made, as closely resembling nature as possible : a brass rod, terminating in a ball, was erected beneath a similar ball proceeding from the prime conductor of the machine, and sparks were passed between the two : beside the rod was held a smaller and shorter one, also terminating in a ball ; the larger rod was screwed into a brass disc, the smaller rested on the floor ; each was separately con- nected with a good discharging train. All things being in order, sparks were thrown from the prime conductor, and " lateral sparks" passed in abundance between the rods : and if this represented a lightning rod, it appeared lawful to infer that in every other arrange- ment when sparks were obtained, they proceeded from the wires being a representation of a lightning rod. Without entering into the various experiments, all tending to develope the same truth, we come to show the explanation this last affords of the action of an elevated rod between two metallic discs. It is well known that such a rod will not give off sparks to vicinal bodies ; but Mr. Walker is of opinion that this want of the la- teral discharge is due to the fact that the vicinal body rests on the lower disc, and is thus a direct metallic connexion with the main rod ; in proof of which he shows, that the sparks in his experiment just noticed, ceases the instant the end of the lower rod touches the disc; and thus too are confirmed the principles described in his former paper, by which the safety of lightning rods is ensured by establishing such contact. 3. " On a new form of Battery, particularly adapted to Blasting Rocks," &c. By Martyn Roberts, Esq., F.R.S. Ed., Memb. This battery consists of alternate and parallel plates of iron and zinc, and is excited by sulphuric acid 1 + , water 30 : the plates are supported in a frame, by which they can readily be immersed in the trough of liquid (which may be of wood luted with white lead), and be removed at the termination of the experiment. The peculiar features of this battery in contradistinction to others, are the modes of connecting the plates. If we consider the figures 1, 2, 3, 4, &c. to represent the zinc plates, and the letters a, b, c, d, &c. the iron, a and b must be first connected ; then 1 and c, 2 and d, 3 and e, and so on, by which means both sides of each plate are brought into re- quisition, and no counter currents reduce the action. Mr. Roberts recommends a series of twenty for blasting, and says that they may be comprised within a space of eight inches. 4. Electro-Meteorological Register for June, by W. H. Weekes, Esq., Memb. Aug. 16.— A Letter from Walter Hawkins, Esq., F.S.A., F.Z.S., 3 1 2 London Electrical Society. M emb. Elect. Soc, was read, in which allusion was made to the recent serious accidents occasioned by lightning, and which suggested the propriety of the Society's taking the matter into consideration, and publishing some general directions as to the best methods of pro- tecting churches and other elevated buildings. A paper from a member, Mr. Mackrell, was then read, detailing the plan by which he had succeeded in obtaining ferric acid by electrolysis. A paper by Henry Letheby, Esq., A.L.S., was read, detailing the particulars of the dissection of a Gymnotus Electricus, and containing reasons for believing that the electric energy originates in the brain and spinal cord. In reference to the anatomy of the fish, the author shows that the electrical organs are not super- additions of a peculiar structure, but are the result of an increased development of the aponeurotic termuscular septa, which become so arranged as to form long tubes, running diagonally from within outwards, so that the juxtaposition of these tubes produces laminae which run longitudinal to the animal. The number of tubes in the entire organs is estimated at upwards of half a million. The organ is supplied largely by the spinal nerves ; the peculiar nerve of Hunter, called by Mr. Letheby the posterior or dorsal branch of the fifth, is distributed entirely to the muscles. The author then alludes to the well-known researches of Williamson, Humboldt, Faraday, Walsh, Todd, Davy, Matteucci and others, which have proved the analogy between the effects pro- duced by electrical fishes, and those developed by our artificial com- binations. He then goes on to trace the connexion between these two divisions of the subject, and directs attention to two important facts : — 1st, that the organs are made up of aponeurotic septa con- taining an albuminous gelatinous fluid ; and 2ndly, that these are furnished with a supply of nerves far exceeding the wants of the parts for the purposes of life. Bearing in mind this latter fact, and then alluding to the voluntary nature of the shock, to its annihilation when the nerves are severed, to its increase when the nerves are irritated, he concludes that the electric force originates in the brain and spinal cord, and is concentrated or made tense in the organ itself. He then gives a series of deductions to show that electricity and vital energy are in a manner identical. This paper was illustrated by an elaborate series of drawings, and also by anatomical preparations of the organ and the supplying nerves. Mr. Weekes's Electro-Meteorological Report for July was then read, from which we gather that while the metropolis has been so seriously visited by lightning, the neighbourhood of Sandwich has been comparatively tranquil. September 20. — The papers read this evening were, — 1st, " Additional Notes on the Production of Acari, &c. in close Atmo- spheres, incident to the operation of Voltaic Currents." By W. H. Weekes, Esq., M.E.S. Mr. Weekes finds, from continued observation, that these insects, whatever be their origin, are multiplied by the ordinary means of Mr. W. S. Harris on Lightning Conductors. SI 3 © generation : he has observed the devolopment and departure of suc- cessive families, and perceives that the defunct are devoured by their survivors. On the 20th of July, 1842, he terminated the ex- periment with the sulphate battery, and was so unfortunate as not to secure a single specimen of the insect. With respect to the spongy aggregations around the positive electrode, he has found they are not, as he anticipated, pure silicon, but apparently an in- ferior oxide of that element. He quotes Dr. Brown's opinion, that " it may throw light on the doubtful question of the atomic weight of silicon." 2nd. " Observations by W. Snow Harris, Esq., F.R.S., on a paper by Charles V. Walker, Esq., Hon. Sec. L.E.S., entitled ' On the Action of Lightning Conductors.' " The author of this paper does not agree with Mr. Walker in fearing danger from the passage of a spark from the lightning-rod to a vicinal conducting body; and he thinks, contrary to Mr. Walker, that the discharge of a Leyden jar does resemble a flash of lightning. He says, that " the lightning-rod, so far from send- ing out sparks to neighbouring bodies, directs the passing charge from them altogether." He states, that " when a great variety of circuits are open to a passing discharge of electricity or light- ning, the charge will be likely to divide on them all ;" and that this is by no means a new fact : this he alludes to as the divi- sion of charge. He adds, that it will not go off to semi-insulated bodies ; and this he appears to consider " lateral discharge." He then proceeds to analyse Mr. Walker's experiments, which had in- duced the latter gentleman to doubt the analogy between Leyden and lightning discharges, and allows the distinction between the two cases, but not the difference. He conceives that the difference in the direction of the discharge does not operate against its special character. With respect to the difference in the length of spark, he considers this as " altogether an affair of intensity, and of the form and disposition of the charged conductors ;" and proceeds to show varied phenomena, in connection with varied form and ar- rangement. He does not place so much reliance as Mr. Walker upon experiments from the prime conductor, but allows certain gene- ral points in which it does resemble a charged cloud. He then ex- amines the experiments which were made with the prime conductor of the Polytechnic Institution, and shows in what respects he is unwilling to receive them. He concludes with expressing a conviction that there is no danger of lightning leaving a conductor to enter vicinal bodies ; and hence considers that Mr. Walker's suggestions relative to connecting these bodies with the main rod, are not needed. Mr. Weekes's Electro-Meteorological Register for August was then laid before the Society. - CHEMICAL SOCIETY. [Continued from vol. xx. p. 344.] Dec. 21, 1841 . — The following communications were read : — " On the Agency of Caloric in permanently modifying the state 314- Chemical Society. of Aggregation of the Molecules of Bodies," by Warren De la Rue, Esq. The subject of this short notice is the practical application of the action which takes place in masses, composed of palpable particles, when raised to a temperature insufficient even for their partial fu- sion. In illustration of the particular action alluded to, may be quoted the following familiar facts : — Precipitated gold, when heated to a low red heat, contracts in volume, becomes more coherent and yellow in colour ; clay contracts in volume when heated, and generally in pro- portion to the intensity of the heat ; the carbonaceous deposit in the inside of gas retorts, by the continued action of heat, acquires suffi- cient hardness to scratch glass ; ordinary coke and charcoal become harder the longer the action of heat is continued on them ; these and many other analogous facts are examples of a new molecular arrange- ment being produced in various substances, by subjecting them to an increase of temperature, not however sufficient for their fusion. To cause the foregoing changes a red heat is employed ; we shall however presently see that a temperature but little above that of boiling water is quite sufficient to materially alter the cohesion of some substances. It may be as well here to premise, that the particles should be brought as closely as possible together ; to effect this, if the sub- stance be in powder, it must be made into a paste with water to displace the air, and the paste so prepared submitted to a pressure of four tons or upwards on the square inch ; air being so exceedingly compressible it cannot be got rid of without the use of some liquid. The manner of pressing need not here be entered on, the operation being purely mechanical. White lead precipitated by carbonic acid gas from a hot solution of the sub-nitrate always falls as an exceedingly light deposit ; if it be pressed as before described, and the pressed cake dried at the or- dinary temperature of the atmosphere, it coheres but imperfectly, but on being subjected to a heat of between 200° and 300° Fahrenheit, it becomes exceedingly hard and compact ; and if the cake be ground up with water and redried, it will be found far more dense and opake than the original precipitate, showing the change to be permanent. The following fact was communicated to me by Messrs. Nasmyth and Co. of Patricroft : — Common chalk cannot readily be sawn into thin slips, as it crumbles under the operation ; if however it be baked at the temperature before named it becomes far more tenacious, and may be then cut into any form we choose, still being sufficiently soft for drawing or writing, to which purposes it is far more applicable than before baking. Almost all precipitates dry much more crisp at high than at low temperatures, the agency of heat facilitating the attraction of such particles as may happen to be in contact. In conclusion, I may remark that it appears by no means impro- bable that the long- continued action of temperatures, but slightly elevated above the ordinary temperature of the atmosphere, may Chemical Society. 315 have been, and still may be, the cause of the formation of hard rocks from materials originally but slightly coherent. " Notice of the Decomposition of Oxalic Methylic yEther (Oxa- late of Oxide of Methyl) by Alcohol," by Henry Croft, Esq. While in Berlin I was led to examine the action of potassa on oxalate of methyl, by a statement of Weidmann and Schweitzer in their first treatise on Wood-spirit ; namely, that the compounds of the oxide of methyl with acids are decomposed by alkalies, not into their constituent acid and wood-spirit, as Dumas and Peligot have stated, but into the acid and a peculiar oil which they called methol. From this Lbwig drew some conclusions unfavourable to the accu- racy of Dumas and Peligot's research. This statement of Weidmann and Schweitzer I found to be incorrect, as they themselves also al- lowed in their second paper. Oxalate of methyl is best prepared by distilling a mixture of 1 part wood-spirit, 1 part anhydrous oxalic acid (HO + O203), and from £th to ^th of sulphuric acid. The first portion which passes over may be returned, and afterwards an- other part of wood- spirit added, or even two. The aether obtained must not be allowed to stand in solution for any length of time, for it easily decomposes. The above proportions I have found to be the best ; the method with oxalic acid alone is troublesome, on account of the great volatility of wood-spirit, and the length of time required for forming any considerable quantity of the aether. If, on the other hand, so much as an equal weight of sulphuric acid is taken, the mixture becomes brown or black, and towards the end of the ope- ration sulphurous acid, methol, and other products are formed. By passing hydrochloric acid gas into a solution of oxalic acid in wood- spirit no aether could be obtained ; it is possible, however, that the result of further experiments may be more favourable, only one ex- periment being made, owing to the very small quantity of wood- spirit in my possession. It is well known that Mitscherlich formed the oxalovinate of po- tassa by adding to an alcoholic solution of oxalic aether just so much of an alcoholic solution of potassa as was sufficient to saturate half the oxalic acid contained in the aether. As no acid oxalate of methyl is known, I therefore attempted to form it in the same manner, but owing to the excessively small quantity of spirit which I possessed, and which is not to be obtained in northern Germany, I was obliged to dissolve both the oxalic methylic aether and the potassa in alcohol, it appearing very unlikely that the alcohol could have any disturb- ing influence, as it is only the aether which ought to be decomposed. On adding the solution of potassa until the mixture became slightly alkaline, a white salt in pearly scales was obtained ; this was washed with alcohol and dried. The filtered solution gave more of it on evaporation. In analysing this substance it was useless to attempt to determine the carbon and hydrogen, owing to the admitted insecureness of the analyses of potash salts, and I had not enough material to prepare either the lead or baryta salt. The oxalic acid and the potassa were therefore alone determined : it contained,— 1st, 3081, and 2nd, 30"76 316 Chemical Society. per cent, of potassa, and 46'58 of oxalic acid. This agrees very well with the formula for oxalomethylate of potassa, plus one atom of water ; but no water could be driven out by a heat of 150° C, and I at length found that the salt was only oxalovinate of potash, with the composition of which the analyses agree very well : — 1. 2. Oxalic acid . . . 46-12 46"58 Potassa .... 3004 3076 30*81 . The salts agreed, moreover, completely in their properties. On re- peating the experiment with wood- spirit instead of alcohol I did not obtain an insoluble salt, but on evaporation one which is probably the true oxalomethylate of potash, and which I am now about examining. Such a decomposition as the above is, I believe, of very rare oc- currence ; I am not aware of any other instance of it being known, although the possibility of some such kind of decomposition has not escaped the acuteness of Berzelius. (Lehrbuch, viii. 703.) We may perhaps suppose that oxalomethylate of potash is first formed, but that the attraction of oxalic acid for aether, and of oxalic aether for oxalate of potash is so strong as to cause the decomposition of hy- drate of aether into its elements, when the alcoholic aether will com- bine with the oxalic acid, and the oxide of methyl, whose place it takes, combines with water to form wood-spirit. That some kind of what is called predisposing affinity is here in play, is evident from the fact that oxalate of methyl may be boiled with alcohol for hours without any such change taking place. It may be stated, in conclusion, that the process last described is a very good and oeconomical method of obtaining the oxalovinate of potassa in a very beautiful form. " On the Radical of the Cacodyl Series of Compounds," by Pro- fessor Bunsen of Marburg. (In Phil. Mag. S. 3. vol. xx. p. 382.) Jan.. 4, 1842. — The following- communications were read ; — " On some of the Substances contained in the lichens employed for the preparation of Archil and Cudbear," by Edward Schunck, Esq. (This paper will be found in Phil. Mag. S. 3. vol. xx. p. 495.) " On a re-arrangement of the Molecules of a Body after soli- dification," by Robert Warington, Esq. (Inserted in Phil. Mag. S. 3. vol. xx. p. 537.) Jan. 18. — Colonel Yorke exhibited a specimen of a silver ore from Mexico, containing bromide of silver, from his collection, in confir- mation of the late discovery, by M. Berthier, of the existence of bromine in silver ores. The following communications were read : — " On the Conversion of Benzoic Acid into Hippuric Acid, in the Animal Economy," by Mr. Alfred Baring Garrod, of University Col- lege. (In Phil. Mag. S. 3. vol. xx. p. 501.) ' On the Constitution of the Sulphates, as illustrated by late Thermometrical Researches," by Thomas Graham, Esq., F.R.S. (In Phil. Mag. S. 3. vol. xx. p. 539.) February 1 . — The following communication was read : — '* On the Change of Colour in the Biniodide of Mercury," by Chemical Society. 317 Robert Warington, Esq., Sec. Chem. Soc. This paper will be found at p. 192 of the present volume. February 15. — The following communications were read : — " On a new Oxalate of Chromium and Potash," by Henry Croft, Esq. For this paper also see pres. vol. p. 197. " Some Observations on Brewing," by Septimus Piesse, Esq. The author's attention was directed to the subject by the follow- ing inquiry : — " Is it possible to obtain a greater quantity of extract from malt by any other process than that usually followed ? Is any thing left in the grains which ought to be in the wort ? " Now from an examination of several samples of the malt taken when supposed to be completely exhausted, and from the circum- stance of the grains affording such a large quantity of nourishment to cattle, I was led to suspect that it was possible to increase the weight of extract ; in fact, the grains were found to contain a nota- ble quantity of starch. The non-conversion of this starch into sugar does not depend, in the cases I have witnessed, upon the use of improper temperatures, but arises from a deficiency of diastase (the principle which effects the change of starch into sugar). In the ordinary process of brew- ing, a certain quantity of water and malt are mixed together of a proper temperature. After standing for a time, this water, or as it is then termed, wort, is drained from the malt, and a second portion of water is run on to form the second wort. There can be no doubt but the principal portion of the starch is converted during the first mashing, but it never is all. Now it must be remembered that as diastase is soluble, it is taken up by the first wort, and when that is run off, the diastase passes away also. The improvement consists simply in adding diastase to the second wort, to convert the remain- ing starch into sugar. This is done by the addition of a portion of malt (which contains diastase) previous to mashing a second time. In a brewing of 30 quarters, I should take 29 quarters for the first mash, and add the remaining quarter to the second. There is such an increase as to warrant me in advising its adoption by all brewers and distillers. Another improvement in brewing is recommended by the author, to prevent the absorption of oxygen by the wort, and thus in a great measure prevent acidity. The wort, as it flows from the tun, passes into the underback, according to the usual practice, where it is exposed to the air ; and that for some time, because the wort must run slowly in order to come bright. The improvement consists in having a float in the back, that is, a surface of wood the size of the bottom of the back, upon which it rests when empty. As the wort runs into the back the float rises with it, and falls again when it is pumped up to the copper, thus effectually keeping it out of the contact of air previous to boiling, when the danger ceases. When this precaution has not been taken, I have invariably found the wort to indicate more or less acid, which may be looked upon as likely to lead to sour beer. March 1 . — The following communications were read : — 318 Chemical Society: — Mr. Hutchinson on the "On the Preparation of Cyanide of Potassium, and its applica- tions," hy Professor Liebigof Giessen. (Inserted in vol. xx. p. 2G5.) " On the Specific Heat and Conducting Power of Building Ma- terials," by John Hutchinson, Esq. The following is the substance of Mr. Hutchinson's paper : — The author, after mentioning the state of our knowledge respecting the conducting powers for heat of different substances, proceeds to point out an important source of error in all such investigations hitherto made arising from the neglect of correction for differences of specific heat among the bodies examined ; the effects observed being evi- dently mixed effects, arising from both causes. This being the case, before any correct investigation of the relative conducting powers of building materials referred to could be advantageously undertaken, it became indispensable to acquire a previous knowledge of their relative capacities for heat, in order that correction for differences of this kind might be made. This inquiry, therefore, naturally pre- ceding that of the proper subject of the paper, first attracted the author's attention. The building materials selected for experiment were the following : — Oak, beech and fir-woods ; common, facing and fire-brick ; As- phalte composition, hair and lime mortar, lath and plaster, Roman cement, plaster and sand, plaster of Paris, Keene's cement ; slate, Yorkshire flag-stone, Lunelle marble, Napoleon marble, Portland and Bath-stone ; and lastly, three specimens of the stones now used in building the Houses of Parliament. The plan of experimenting chosen was that known as the " method of mixture," this appearing by all evidence on the subject to be the most unobjectionable. The process followed differed but little from that described by Regnault in his recent researches. A suitable quan- tity of material in fragments being accurately weighed out and placed in a little wire basket with the bulb of a delicate thermometer in the midst, the whole was exposed in au inclosure heated by steam until the thermometer ceased to rise, when the basket was withdrawn and plunged with suitable precautions into a vessel of water at a tempe- rature a little below that of the atmosphere. After the lapse of a very short interval the temperature of the water was carefully ob- served, and its rise gave the means of calculating the specific heat of the substance. The author remarks on the necessity of equalizing as much as pos- sible the times of heating of the different substances, having observed a great difference in the results given by the same body when slowly and when quickly raised to the high temperature required for the ex- periment, and attributes this difference to an alteration in the state of the currents or waves of heat travelling inwards towards the centre of the solid. A number of minute precautions, indispensable to a correct result, were also pointed out and exemplified. The results of the investiga- tion were given in a tabular form, and the principle of the calculation described. With the knowledge thus obtained the author proceeded with his Specific Heat and Conducting Power of Building Materials. 319 inquiries respecting the conducting powers of the substances under examination. The plan usually adopted in this kind of research, namely, ob- serving by the aid of thermometers the time occupied by the passage of a certain amount of heat lengthways through the substance of a prism, one end of which was exposed to a high and constant tem- perature, having failed on trial with these bodies, in consequence of their feeble conducting powers, the following method was had re- course to with perfect success : — The various substances examined were cut with the greatest care into cubes of 2*8 inches in the side, and a hole drilled in the centre of one of the faces half way through, large enough to receive the bulb of an exceedingly sensitive thermo- meter, together with a little mercury to improve the contact with the substance of the cube. The temperature of the mass being exactly observed, it was next plunged, all but its upper surface, into a large bath of mercury heated by steam, whose temperature remained con- stant at 211°, and the time of rise of the thermometer for every suc- cessive 10° accurately noted until the maximum was reached, thus affording a comparison of the relative conducting powers, or perhaps more properly, resistance to the passage of heat towards the centre of the mass. In the course of these experiments a very extraordinary circum- stance was observed : although the greatest care was taken to equal- ize the temperature of the cubes by suffering them to remain at least twenty-four hours before experimenting in an uniform temperature, yet they never exactly acquired that of the room, or even agreed among themselves in this respect ; an observation which led the au- thor to the suspicion that the generally received doctrine of an equal distribution of sensible heat among bodies in contact and not influ- enced by external sources of disturbance, might not prove strictly true, but that, on the contrary, each of a number of different sub- stances, exposed under similar circumstances to the influence of a medium of uniform temperature, acquires a proper temperature of its own. The same thing was observed with higher degrees of heat ; a mass of slate, for example, plunged beneath the surface of uniformly heated mercury and maintained there long after the thermometer in the slate had reached its maximum, always exhibited a temperature decidedly below that of the surrounding metal*. A third series of experiments were made with a view of ascer- taining the relative rates of cooling in air of the various materials examined, from a higher temperature to that of the atmosphere. The arrangement consisted of the cubes before described, covered externally with thin paper for the sake of uniformity of surface, the same delicate thermometer being inserted in the hole in the centre, together with a little mercury for the sake of contact. The cubes were each in turn heated in the steam-chest used for the specific heat experiments, until the included thermometer rose to 200° ; they were then removed, suspended in the air, and the time of fall of tem- perature for every 10 degrees carefully no'.ed. [* On this subject a paper by Mr. Parnell was subsequently read, an abstract of which will appear in a future Number. — Edit.] 320 Intelligence and Miscellaneous Articles. The precautions required to be taken to avoid errors of different kinds were fully described, and drawings of the apparatus used ex- hibited, together with a most elaborate and complete set of tables embodying the whole of the results. LIV. Intelligence and Miscellaneous Articles. BICHLORIDE OF HYDROGEN. r|1HIS compound, which contains one proportion of chlorine more -■• than exists in hydrochloric acid, may be obtained, according to M. Millon, by slowly and gradually projecting binoxide of lead into con- centrated hydrochloric acid, surrounded by a cooling mixture of ice and salt. In the reaction which occurs under these circumstances, the liquor produced assumes a deep yellow colour, without any sen- sible disengagement of chlorine, and an abundance of protochloride [of lead] is formed. The bichloride of hydrogen, which gives the liquor its colour and properties, has not yet been separated from the medium in which it is dissolved. This compound possesses but little stability, for, at common temperatures, it continues to evolve chlorine during several days. Mercury decomposes it by absorbing part of the chlorine, and thus causing the reproduction of hydrochloric acid. Its compo- sition would appear to be 1 equivalent of hydrogen -f- 2 equiva- lents of chlorine = H Ch'2. This bichloride would be formed by the reaction of 3 equivalents of hydrochloric acid, or 1 equivalent of binoxide of lead, as shown by the annexed equation : 3 H Ch, + Pb O2 = Pb Ch + 2 H O, + H Ch2. Journal de Chim. Me'dicale, Juillet 1842. ON THE ACTION OF CHLORIDES UPON PROTOCHLORIDE OF MER- CURY. BY M. MIALHE. M. Mialhe remarks that Capelle, in 1763, first observed the dan- ger arising from a mixture of calomel and sal-ammoniac ; Proust after- wards proved the conversion of calomel into corrosive sublimate by the action of the alkaline chlorides. After mentioning other au- thors, M. Mialhe refers to a note of. his own contained in the Jour- nal de Pharmacie for February 1840, in which he details experiments proving, — 1st, that calomel acted upon by the alkaline chlorides al- ways yields more or less corrosive sublimate ; 2ndly, that it is to this partial conversion calomel owes its medicinal powers; and he afterwards mentions different authors who have confirmed his opi- nions. M. Mialhe then relates various experiments which he has since performed to determine the proportion of corrosive sublimate result- ing, under certain conditions, from this action. Experiment I. — 1000* parts of distilled water, GO of common salt, 60 of sal-ammoniac, and 60 of calomel ( -n. ►O -i « 0) Q fc. ^ Si?.© O I) o u ^ "a . B .9 5 5 * g ■«• ° III ^£cj ^"s > ? *c2 pi ° J » O O .ft * w .$~3Q ;utod j 'vmt «'i'«oni«©o-'?ifflKXt'f5«««a)i :OCl-1'tO — «-"^-m-«0D iO OtOtOtOSO »0 CO OtO »0 U)!0!0t00t0!00t0(0 to tO ic tO 'O SO <0 <0 SO ^ •jpiAipuBg •ojiqs -saujiunff •jpi.nsiqo "ib6"s-H : uopuoT : in — >-* © •jjotMpireg 'X3U5140 •aitqs -ssu/umq ■urd i •jptMSiqj •iu-B6-s"a : uopuoi •urd f8 •uijtf XBW •urB?8 •XBm •IU-B t) UqBj •r- 3j a « c *fl ^•E •ut-B $8 •U0}S0t[ •uub6 •oos "Xoy : uopuo'i J!) 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X©tOtO©rN.OS^^ : CO CO tO Cl Cl !•>. ©to^HCOOcoxcix-rci-^-'iN.ip^Hi I ~* -< OS OS © :~. . ) X tN OS OS OS "r. © <— * )©©OOSOS©OiOSOSOSOSOSC COCOCldClCldCOCOdCOCOCOCOCOCOCOClClCOClClClCNCICltNeNClCOCO ) © © Cl -+ "O © c )XtOCItOXXCltj — « ©) C CO »0 (OKCC-'XhU),! -!• CO © — -.t; co ci © sn -c. , CO CO CO cV CN Cl' CO CO CO Cl Cl CO CO CO CO CO CO CO CN' CO CO CO d Cl' cY cY CO CO CO CO CO t-nCNCO'J'OtOlN.XOS© — CNCO-ftfStOI^XOS©— -C1CO' JtOKXCsC^ ICICICICICKNCICICICOCO o THE LONDON, EDINBURGH and DUBLIN PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. [THIRD SERIES.] NOVEMBER 1842. I LV. Letter addressed by M. Edmond Becquerel to the Editors of the Annales de Chimie et de Physique, in Reply to Mr. Daniell's Letter to Mr. R. Phillips on the Constant Voltaic Battery, inserted in the Phil. Mag. for April 1842*. N the Annates de Chimie et de Physique for December 184-1 , I published a Notice on constant voltaic batteries, in which I stated the facts relating to the subject just as they result from experiments performed by various natural philo- sophers who have been occupied with this subject. Mr. Daniel], thinking that I had not done him justice, has thought it necessary to reply to several of my assertions in the Philosophical Magazine for April 1842. It was far from my intention to have wished to say anything which might be displeasing to him, and to have sought to misrepresent facts, with a view to attribute to my father a discovery which did not belong to him ; in this respect Mr. Daniell is strangely mistaken as to my intentions, and without this motive, I should not have replied to him, having nothing to change, with re- spect to the main point, in the facts which I mentioned in my notice. In every physical question three things are to be considered ; the idea, the principle, and the applications. Now, it is proved by undoubted facts, that from 1829, and even several years before, my father had invented and constructed constant vol- taic batteries, which, in truth, had not the power of action and the advantages possessed by the constant voltaic batteries of Mr. Daniel], who made them known in 1836. The ap- paratus invented by my father at once received the denomina- * From the Ann. de Chim. et de Phys. for August 1842 (Third Series, vol. v. p. 412), published towards the end of September. Phil. Mag. S. 3. Vol. 21. No. 139. Nov. 1842. Z 330 M. Edmond Becquerel on the Constant tion of constant voltaic batteries (appareils a courant constant), and, as they still perfectly fulfil the purpose he had intended, it is impossible to contend with him for the idea, the principle, or the application within certain limits. The details into which I shall enter will leave no doubt about the priority of invention, at least I hope so. For more than fifteen years the electro-chemical reactions, by means of which my father was enabled to obtain crystallized mineral substances, were produced by the aid of small apparatus com- posed of tubes in the form of the letter U, closed at their cur- vature by a partition of moist clay designed to separate the two liquids placed in the two branches of each tube, one of which contained a solution of sulphate, nitrate or chloride of copper in contact with a plate of copper, and the other con- tained a solution of sea-salt, into which a plate of zinc or of another metal was immersed. Such is the arrangement of the simple apparatus which is scientifically known by the name of pile a cloison*. The form of this apparatus is of little importance, since it may be infinitely varied : for example, instead of a tube in the form of a U, we may take any kind of vessel, separated into two compartments by a diaphragm of bladder, baked earth, plaster, or linen, &c. But all these various modifica- tions enter into the principle of the U-tube. After the year 1829, and before Mr. DanielPs publication, my father made several communications relating to the same subject ; in fact, we find in the Compte Rendu des Seances de VAcademie des Sciences for 1835, the description of an appa- ratus giving a current which was sensibly constant for two entire days. According to this, therefore, Mr. Daniell cannot pretend to the discovery of the general principle on which the con- struction of constant voltaic batteries rests, but he may justly claim the good arrangement which he has given to his pile, and, amongst others, the advantage of always having a satu- rated solution of sulphate of copper, and of obtaining in a small compass effects far more energetic than those for which my father had occasion in the beginning, for the production of crystallized substances analogous to those formed by na- ture, a discovery for which he received the Copley Medal from the Royal Society of London, and which Mr. Daniell himself received some time after for the constant voltaic battery. Mr. Daniell, notwithstanding facts so evident, declares in his * An English translation of the description of this apparatus, and of M. Becquerel's Researches on Crystallization produced by Voltaic Action, was published in Taylor's Scientific Memoirs, Part 3. Jan. 1837. — Ed. Voltaic Battery, in Reply to Mr. Daniell. 331 answer that he was not guided by the works of his predecessors in the construction of his battery, and that the principles upon which it rests are different from those which my father had long since admitted. He states, for example, that the rapid diminution, as well as the definitive cessation of the cur- rent in ordinary batteries, are due to the deposition of zinc on the negative plates of each couple. "We agree perfectly upon this point; the annihilating action produced by the presence of the zinc comes under that designated by the term polarization of the electrodes. In my Notice, indeed, I men- tion, p. 438, in the eighth and following lines, that " each negative plate (of copper or of platinum) retains on its sur- face alkaline elements, such as hydrogen arising from the de- composition of water, and bases arising from the decomposi- tion of saline matters dissolved in water." This phrase does not exclude any of the bases ; the zinc therefore arising from the decomposition of the salt of zinc must equally be deposited on the negative plate. This deposition being effected, the action of the liquid on the zinc necessarily gives birth to a counter- current which more and more destroys the action of the first; in order to have an apparatus of continued force, it was necessary to prevent the zinc and the alkalies from being deposited on the negative electrodes. Mr. Daniell afterwards says that the passage of the electric current across diaphragms of bladder is well known to expe- rimentalists; he quotes Dr. Ritchie as having made use of them. To which I reply, that the use of diaphragms in physics is very ancient, since one of the Bernoullis had already se- parated two different liquids by a membrane, in an experi- ment in which he wished to produce an effect of endosmose. Porrett also adopted the same expedient in order to show that in separating, by means of a membrane, a mass of water into two parts, into each of which a plate of platinum was plunged communicating with one of the poles of a battery pile, the water passed from the positive into the negative compartment. 1 might still quote other examples ; but the use of membranes, of diaphragms permitting the current to pass in order to obtain a couple giving a constant current, was brought into use by my father nine or ten years before Mr. Daniell was occupied with this question, and particularly in the experiments communicated to the Academie des Sciences on the 23rd of February, 1829*. As to the publication of Dr. Ritchie in the Philosophical Transactions, it is of the month of May 1829, and conse- quently some months later, I therefore look upon Mr.Daniell's * Ann. de Vhys. et de Chimie, t. xli. Z2 332 M. Edmond Becquerel in Reply to Mr. Daniell. pile, although very convenient, as based upon the same prin- ciples as the apparatus which my father has used for a long time. Further on Mr. Daniell adds : " Even in the use of the diaphragm, which might at first sight appear similar, there is a direct opposition, for my object is to keep the two electro- lytes which I employ perfectly separate, so that no portion of one may penetrate to the other, except in the process of electrolysis." I confess that I know not how Mr. Daniell can separate two liquids by a membrane moistened by them and which they can penetrate, without that passage from one to the other taking place which is otherwise called endosmose and exos- mose. It is impossible to realize this condition; the only means of retarding for as long a time as possible the mixture of the two liquids, is by substituting for the membrane a thick diaphragm of clay, as did my father; the intensity of the cur- rent is then diminished, but constant effects are obtained which may continue for months, for years. Still further on Mr. Daniell says : " and I repeat, that in my constant battery nothing depends upon the contact and action of the two liquids upon each other." I do not understand this assertion; for every one knows that two different liquids acting upon each other by an intermedial membrane, disengage electricity enough to produce a current ; and if Mr. Daniell wishes to convince himself of it, he has only to take away, in one of his couples, the plate of zinc and that of copper, and to substitute two plates of platina for them ; he will have a current owing to the reaction of the two liquids upon each other, less intense indeed than that obtained with a couple in which an oxidable metal is included. Mr. Daniell also says, that " the amount of force obtained by my father's apparatus is insignificant with regard to its ap- plication to the arts." I will reply yes and no to him; yes, if there is a question of apparatus like those of Mr. Daniell, designed to obtain cur- rents which are to be transmitted into liquids placed in se- parate vessels; no, if the currents are to react chemically on the liquids making a part of the apparatus themselves. In short, the apparatus constructed by my father, six years ago, for the treatment of ores of silver of lead and of copper, are based on the same principles whioh I have before ex- plained, and are of much more considerable dimensions than those of Mr. Daniell, since each couple requires 1000 litres of liquid to act, and six similar couples have been united, so that 6000 litres have acted at the same time, and the Prof. Grove's Remarks on a Letter o/Prof. Daniell. 333 energy of action has been still greater than that produced with the apparatus of Mr. Daniell, since all the silver and the lead contained in the ores, that is to say about one kilogramme of silver and 100 kilogrammes of lead, were extracted in the space of a few hours. I now leave it to the judgement of the reader which is in the right, Mr. Daniell or myself; and it will then be seen whether Jilial piety blinded me, or whether I have not rather been actuated by the love of truth. Paris, July 7, 1842. LVI. Remarks on a Letter of Professor Daniell contained in the Philosophical Magazine for April. By W. R. Grove, Esq., M.A.f F.R.S., Professor of Experimental Philosophy in the London Institution. To the Editors of the Philosophical Magazine and Journal. Gentlemen, A LLO W me to request your insertion of a few remarks on ■£*- a letter of Professor Daniell published in your Magazine for April. Absence from London and occupations of other than a scientific nature prevented my noticing it at the time ; my attention has been recalled to the matter by its republi- cation in the Annales de Chimie. A few words at the conclusion of this letter refer to me : after stating that M. Becquerel has inadvertently described my experiments as anterior to Mr. DanielFs, this gentleman goes on to say, " Professor Grove has never spoken of his battery but as the further application of principles which I had previously deduced." It is perhaps of little moment to the public what principles led me to the construction of the battery in question, but it may be of some moment to me, as should I, by silence, be held to assent to certain principles, I may be accused of contradic- tion and inconsistency if in any future paper I should state my adherence to others. M. Becquerel, again, in the 5th volume of his Traite de V Electricite, describes my battery as " Pile voltaique construite d'apres les principes exposes dans les chapitres ler, &c .:" these chapters contain the papers of M. Becquerel in respect of which he claims priority to Mr. Daniell. It is obvious, that as M. Becquerel and Mr. Daniell differ in their notions as to the principles of the con- stant battery, I could not derive my battery from both, and I have looked over my papers on this subject to see whether I have expressly referred it to principles enounced by either 334- Prof. Grove's Remarks on a Letter of Prof. Daniell. of these philosophers ; I cannot see that I have. I have on many occasions mentioned their experiments before my own in the history of the voltaic pile, both as acknowledging their priority and as not wishing to claim what was not my due ; probably it is this which has led to a misconception on the part of Mr. Daniell, but I have distinctly stated the idea which immediately led to the construction of my battery in the paper which describes it (Phil. Mag., May 1839). After de- tailing an experiment with two strips of gold-leaf in nitric and hydrochloric acids separated by a porous diaphragm, and showing that upon contact of the two strips the gold in the hydrochloric acid was dissolved, and that a voltaic current was established, I say, " It now occurred to me, that as gold, platina and two acids gave so powerful an electric current," a fortiori " the same arrangement, with the substitution of zinc for gold, must form a combination more energetic than any yet known :" this was the simple deduction which led to my subsequent experiments. I have in most cases been content to publish experiments with no more of theory than was re- quisite to connect them ; it is a general and I think a just com- plaint that there are already too many speculations on this sub- ject ; but in a letter published in the Philosophical Magazine for Feb. 1839, p. 129, previous to the discovery of my battery, I gave my own notions of the principles of voltaic batteries, notions which in some respects agree with those of Mr. Daniell, but which also suggest some new views of voltaic ac* tion. There is one experiment there detailed in which copper is reduced by copper, which had much influence on my subse- quent experiments, but which is not explicable by any prin- ciples laid down by Mr. Daniell; at the conclusion of this paper I say, " if these principles be correct, very superior combinations may be discovered:" how this prediction has been fulfilled the public is the best judged Far be it from me to disclaim any assistance from the ex- periments of Mr. Daniell or of M. Becquerel; I shall ever re- tain a grateful recollection of the assistance rendered to my first efforts in science by the latter gentleman. I cannot at this distance of time well describe what effect their experiments had upon my mind. In the progress of science it is difficult to define the frequently unperceived effect of prior discoveries upon subsequent experimentalists, but I cannot for many rea- sons acquiesce in the assertion of Mr. Daniell above quoted. Mr. Daniell was for a long time attached to the theory of the deposition of metals in the voltaic circuit being the result of a secondary action of the nascent hydrogen, a theory ge- nerally adopted until combated by Hisinger and Berzelius ; thus Prof. Grove's Remarks on a Letter of Prof. Daniell. 335 in his papers, Phil. Trans., 1836, p. 117 etseq., he proceeds to explain his constant battery as dependent upon the removal of that hydrogen by causing it to deoxidate copper: in a subsequent publication (Phil. Trans., 1839) he abandons this view, and considers the deposition of the copper as " a primary result of electrolytic action." This would altogether alter the theory of his battery and of mine. I do not think it is a matter of great consequence which theory be adopted ; each • has many peculiar difficulties, each tends to many similar conclusions, and either may lead to equally successful experi- mental results. Theory is valuable as a means not as an end, and that theory of the voltaic battery is in my opinion the best which best collates the observed phaenomena and which leads to the discovery of the best voltaic combinations. But although I would hesitate, without more conclusive experi- ments, in ascribing this superiority to either of these theories, there is another principle of the voltaic battery enounced by Mr. Daniell, as to which, so far from agreeing with him, I must take leave (with every respect for his scientific attainments) to differ toto ccelo : it is as to the relative extent of surface to be given to the metals of voltaic combinations. Mr. Daniell has in the Phil. Trans, for 1836, p. 128, and in several subse- quent papers, stated that the best theoretical form for a voltaic combination is when the generating metal is arranged with regard to the conducting one as the centre of a sphere to its periphery, and recommends a rod within a cylinder as the nearest practical approximation to such an arrangement ; fol- lowing the authority of Mr. Daniell, I first constructed my batteries of this form, but very soon abandoned it (see Phil. Mag. forOct.1839, p. 288) ; and 1 am now convinced, by three years' experience and by repeated experiments, corroborated by the experiments of others, that this is by no means the best form of arrangement, as regards ceconomy either of space, time, or material. I believe the old arrangement of equal sur- faces to be sufficient for most practical purposes ; but the relative size may be considerably modified according to the nature of the electrolytes, the conducting power of the metals, and other circumstances. I cannot enter more fully on this point without writing a paper especially on this subject. P.S. Since the above was written I have received a paper of Mr. Daniell's just printed, Phil. Trans. 1842, part ii., for which I have to thank the author : it contains a series of ex- periments on my battery, and with a voltameter of my con- trivance. In this paper I see Mr. Daniel alters many of his opinions upon the relative size of the plates in voltaic com- binations. [ 336 ] LVII. On the Iodide of Mercury. By H. F. Talbot, Esq.. F.R.S. To the Editors of the Philosophical Magazine and Journal. Gentlemen, YOUR Number for last September contains a paper by Mr. Warington " On the Change of Colour in the Biniodide of Mercury." Permit me to observe, that the facts contained in the first part of that paper were long ago discovered and published by myself, in your Journal (S. 3. vol. ix. p. 2*). As I do not wish to be deprived of the discovery of one of the most curious phaenomena in optics, I beg leave to draw Mr. Warington's attention to that paper, and briefly to re- capitulate its contents. In that memoir I have shown, — 1. That when iodide of mercury is sublimed between two plates of glass nearly in contact with each other, it cools in the form of thin rhombic plates of a pale yellow colour. 2. These often retain their colour when cold, if left undis- turbed. 3. But if such a crystal is disturbed, as for example, by touching it with a needle at any point of its surface, it in- stantly turns scarlet at the point touched, and the scarlet co- lour is rapidly propagated over the whole crystal. I showed this experiment to Sir David Brewster in the year 1836, and I have no doubt he remembers it well, as he expressed great admiration of the beauty of the phenomenon. The crystal was touched with the needle while under examination with a powerful microscope. 4. The crystal moves and is spontaneously agitated during the time it is changing colour. 5. During the progress of this change, the scarlet portion remains bounded by straight lines, very well defined, and par- allel to the edges of the rhombic crystal. 6. I thence drew the conclusion, that the change of colour was caused by the displacement of the rows of molecules or laminae of the crystal. This I think will be admitted to be the true explanation ; and it was one which h ad not been previously suggested. I added, that I thought this phenome- non " the most evident proof we yet possessed of the dependency of colour upon internal molecular arrangement" 7. I also remarked that these little rhombic crystals were very fine objects for the polarizing microscope. The expres- sions of Mr. Warington, that the crystals " in the dark f eld had the appearance of the most splendid gems" have recalled [• On inserting Mr. Warington's paper we referred to Mr.Talbot's pre- vious experiments, as stated by him in Phil. Mag. — Edit.] On the Progress of Embryology in the Year 1840. 337 to my memory the very similar words which I used when I first announced the invention of the polarizing microscope in your Journal (vol. v. p. 324), viz. " The field of view appears scattered with the most brilliant assemblage of highly coloured gems, affording one of the most pleasing sights that can be imagined. The darkness of the ground on which they display themselves greatly en- hances the effect." With regard to the above points, then, I consider that they were sufficiently established by me in 1836. The second part of Mr. Warington's paper, however, con- tains a fact both new and important ; I mean the solution of the yellow crystals in the liquid and the formation of the red ones, of a different form, in their places. But this observa- tion is most strictly analogous to the phenomenon which I discovered in the iodide of lead, and published in your Journal (vol. ix. p+405), viz. the sudden change of a crystal of that salt from the form of a white needle to that of a row of thin yellow regular hexagons lying in a straight line. Such a me- tamorphosis was previously unexampled ; Mr.Warington has now furnished us with a second example (also the iodide of a metal) : I have myself observed something similar in the iodide of tin ; and I recommend the whole subject of the cry- stalline form of the metallic iodides to the renewed and care- ful consideration of chemists. I am glad of the opportunity afforded me by Mr. Waring- ton's paper of again calling attention to these very curious facts, which appear to me to open a path that promises to lead far into those arcana of Nature, the mysteries of molecular action. I remain, Gentlemen, yours, &c, London, Oct. 1, 1842. H. F. TALBOT. LVIII. On the Progress of Embryology in the Year 1S40*. " COME interesting discoveries rendered the past year a highly productive one for embryology. Two main pro- blems which engaged the various physiologists here occupy the foreground, namely, the earliest development of the Mamr malia, and the metamorphoses of the germinal membrane in its transformation into the embryo******. So long as the meta- morphoses of the germinal vesicle following fecundation could be considered only hypothetically, it was assumed that the Pur- kinjean [germinal] vesicle either burst and poured out its con- tents, or became flattened ; and now contributed to the forma- * From Professor Valentin's Report in the Repertorium fur Anatomie und PJjysiologie, Jahrgang 1841. 338 On the Progress of Embryology in the Year 1840. tion of the germinal membrane in one of these two ways. Both theories had been put forth before the discovery of the germinal spot. But when the existence of the latter became known, the discoverer of the same said that probably the macula germinativa represented the first foundation of the germinal membrane. This conjecture obtained more probability from the obvious fact, that the number, size and distribution of the germinal spots alternated according to the different stages. Research, however, first in the Mammalia, and then in Rep- tiles and Fishes, showed that in consequence of fecundation the interior of the germinal vesicle presents new cells, or that (as was seen in the Rabbit) within the germinal vesicle new cells are really built up upon the foundation of the germinal spots." (Introductory Remarks, p. 13.) First stages in the development of the fecundated ovum, espe- cially that of the Mammalia. As was already remarked in the introduction, the most important publications of the past year concerning embryology are concentrated in the subjects of this chapter. We will therefore, before presenting some ex- tracts of the details, state the most important results. With few exceptions, to be mentioned, all the observations have re- ference to the Mammalia, and indeed to the Rabbit. 1. At the period of the rut certain changes have already taken place in the ovarium, the [Graafian] follicles, and the structures appertaining thereto. Through an increased con- gestion of the ovary single follicles become more strongly de- veloped. The germinal spot, which gives the impulse to the formation of the new cells, probably undergoes changes of this kind. From the observations of Negrier, above men- tioned (p. 248), it may be conjectured that in the human fe- male also the period of menstruation is attended by similar phaenomena. 2. Fecundation itself apparently comes to pass in the following manner: a portion of the semen that has been brought to the surface of the ovarium probably passes into the ovum, and gives the stimulus to the formation of cells within the germinal vesicle******. 3. The number of ova prepared for fecundation by the rut, does not correspond with the number of the subsequently fecun- dated ova, but generally exceeds the same. This fact, already known, has been confirmed by the latest researches on the Rabbit. 4. It often happens that more ova pass out of the ovary than are fecundated, or at least than become developed. Herein ac- cord the observations of Barry with those of Pappenheim. The former found in the tubes and uterus unfecundated or On the Progress of Embryology in the Year 1840. 339 aborted ova. In like manner, parts of the [Graafian] follicle which usually remain in the ovary, for example, portions of Barry's ovisac, may be found in the oviducts. 5. Neither the place to which the ova in the tubes and uterus have advanced, nor the size of the same, nor the time that has elapsed since they left the ovary, affords an exact criterion for the degree of their internal development. This position fur- nishes only a confirmation of what was already known******. 6. The germinal vesicle does not disappear nor burst through fecundation, but fills with cells, the formation of which proceeds from the germinal spot : and this takes place by no means in a peculiar manner, but according to a normal mode which mani- fests itself elsewhere. These circumstances, which really ex- tend our knowledge, have been made known by the laborious researches of Barry. The general process is as follows; — It is known that in the interior of the germinal spot there exists a central body, which often becomes surrounded by concentric traces. This body now enlarges and fills with a pellucid fluid. That part of the germinal spot which is directed towards the interior of the germinal vesicle passes into cells, arranged like pill-boxes one within the other, yet so that the pellucid central vesicle remains near to the periphery [of the ovum]. Within the cells thus arisen there are formed new cells. This cell-formation proceeds in layers from the centre towards the periphery. The outer strata of cells are thus pushed further out, and the most external disappear while new inner strata form, so that the middle ones advance to the outer part. In this manner the germinal vesicle becomes filled with masses of cells, while its membrane disappears. But in the situation of what was originally the centre of the germinal spot there are formed two cells, distinguished by their larger size : and out of these two larger cells new cells arise, as before through the formation of cells in cells, — 4, 8, 16, and so on, — the num- ber doubling every time. These two cells of the central part of the germinal spot, with their succeeding cells, form the foundation of the germ. In it, the germ, again, there is to be seen a cell distinguished by its larger size. The nucleus of this latter cell generates, through further development, the foundation of the embryo. It may hence be conceived, that the seminal fluid taken up by imbibition, arrives at what was originally the central part of the germinal spot ; first gives a stimulus to the cell-formation in the peripheral part of the germinal spot, and to the consequences of the same ; then, through the formation of cells, becomes itself the germ ; and that, subsequently, within the germ the nucleus of a principal cell gives the stimulus to the formation of the embryo. Fe- S40 Mr. Earnshaw in Reply to Prof. Kelland on the cundation thus consists in the imbibed seminal fluid stimulating the germinal spot to the cell-formation, according to the type of cells in cells. But many more cells are formed than re- main ; the outer layers being constantly absorbed. 7. The furrows known to be presented by the yelk arise from the formation of cells (see Repertorium, v. 306). Their pre- sence in Fishes was etablished by Rusconi, in Mammals by Barry. In Birds they may either entirely fail, or, as is more probable, be limited to the germinal membrane and not ex- tended to the yelk. 8. The rotation of the yelk or of the embryo in the ovum, pre- viously observed in invertebrated animals and in Batrachian Reptiles, is also found to take place in Fishes and Mammalia. Rusconi perceived this rotation thirty hours after fecundation in ova of the Pike ; so that it is thus] met with where there is a circumscribed germinal membrane. In the Rabbit it was seen by Barry, although he remained in doubt as to the na- ture of the rotating body which was determined by Bischoff. The latter described also vibrating cilia on the superficial cells. It now remains a point of especial interest, to extend the observation to classes which otherwise do not exhibit ci- liary motion, for instance the Crustacea. 9. Of the other structures of the [Graafian] follicle which pass out [of the ovary] along with the ovum, the tunica granulosa and retinaada {discus proligerw) undergo liquefaction ; while within the zona there arise concentric formations of membranes andfuid or semifluid rings. According to Barry, this forma- tion amounts to from four to five membranes. The attenua- tion of the zona above mentioned soon disappears. The chorion is not formed out of the zona, but out of cells, which arise in the tube and are laid down around the metamorphosed struc- tures. [Professor Valentin then proceeds to give details of the ob- servations of Dr. Barry, the principal of which are the fore- going nine. These details will be found in the Philosophical Transactions for 1839 and 1840. Abstracts of them have been already furnished by this Journal.] LIX. On the Theory of Molecular Action according to New- ton's Law: in reply to Professor Kelland. By S. Earn- shaw, M.A., Cambridge *. TJTAVING been long of opinion that the molecular forces •*■ which regulate the vibratory motions of particles cannot vary according to Newton's law of universal gravitation, it * Communicated by the Author. Theory of Molecular Action according to Newton's Law. 341 was with great pleasure that I read in Professor Kelland's letter that the attention of the greatest mathematicians in Eu- rope is now alive to the necessity and importance of having " the difficulties which attend the theory" removed: and I rejoice that Professor Kelland has undertaken the task of thoroughly reviewing the grounds of my opinion. In my memoir on the subject printed in the Cambridge Philosophical Transactions, I have shown, apparently to Professor Kelland's ^«V d2V dV satisfaction, that when -, f2 > ,■ 2-, — , rt are not zero, the medium is incapable of transmitting light, and have dismissed at once as foreign to the subject the case where these quan- tities are zero, which case the Professor argues " embodies the real state of things." The grounds on which I dismissed this case in so summary a manner were these : — 1st. The acknowledged experimental fact of the superpo- sition of waves of light requires that the forces called into play by a displacement should depend only (or at any rate chiefly) on the^r^ power of the displacement. 2ndly. The received explanations of refraction through cry- stals and of other pheenomena, assume that the force of restitu- tion depends only on the^r^ power of the displacement ; and, 3rdly. If -tj^ > , 2 ? ~JW zero>tne nrst powers ol the displacement disappear ; and therefore this case is inconsist- ent with the known results of experiment and the require- ments of received and established theory. Yet Professor Kelland thinks that the real state of things is embodied in the excepted case, and founds his belief on arguments drawn from analytical expressions in his memoir. It appears to me, then, that the shortest way of bringing the controversy to an end, will be to show that the Professor's own investigations, under proper mangement, lead us to the same results as were given in my memoir. At pages 162, 163 of the Professor's paper on Dispersion, we are told that on the hypothesis which he has adopted each of the quantities 2X{^ + ^8^}sin2/4i 2s|*r+^83/2^sin2 ~ Q 1

r = — o- and F r = — -3-, and therefore n* = 0 ; which being substituted, the Professor's equations of motion assume the following forms : — d*a d2/3 ^7 d*2 ~ °' ~dW~0i IT _0' which indicate that on the Newtonian hypothesis no forces are called into play by the vibratory displacements of the particles. Now the Professor, having treated the quantity n2 as finite in all his investigations on this subject, will see that all argu- ments based on them against what I have written fall to the ground, and that my arguments remain in full force. Cambridge, August 19, 1842. LX. Some Additional Remarks upon a Communication of Pro- fessor Kelland, published in the Philosophical Magazine for May last. By the Rev. M. O'Brien, late Fellow of Caius College, Cambridge*. N the Philosophical Magazine for June 1842, I asserted that certain fundamental equations in Professor Kelland's memoir on Dispersion (in the Cambridge Phil. Trans., vol. vi.) were erroneous. A friend has suggested to me that I ought to have proved more distinctly the existence of those errors. This I will now do in the following manner: — (1.) With respect to the equations qf motion in page 159, vol. vi. Camb. Trans. Professor Kelland has overlooked the terms arising from the part of the equation in page 158, which is multiplied by S /3 and 8 y : for instance, there is a term in the expansion of 8 /3 (viz. ^ — -r-lxly \ which gives rise to the d? a. following term in the expression for -j-^ , viz. r J dxdy which term does not appear as it might in Professor Kel- land's equation. And there is another similar term omitted, viz. r ax dz * Communicated by the Author. I upon a Communication of Prof. Kelland. 343 (2.) With respect to the equations at the foot of page 162, we have 8g2 = £Za*+f**ip+g*# + <2.{eflxly +fgly** + eglxlz). Hence expanding sin2 — -£-, and omitting the parts multi- 3S plied by F k6, &c., we have omitting all terms in which an odd power of either 8.r, ly or 82 occurs. Hence the term which Professor Kelland makes out to be zero, equals ef~% /Ce2 § #2 $y\ + higher powers of h\ 'which is clearly not zero. The error by means of which Professor Kelland shows that this term is zero, is quite apparent in the middle of page 162. He reasons upon 8 p just as if it was r, i. e. the distance of the particle whose coordinates are (x + $x) (y + $y) (2 + 8 s) from that whose coordinates are w yz; whereas 8 p is quite a different thing, namely, the perpendicular let fall from the point x y z on the wave surface passing through the point (x + tixj (y + $y) (2 + 82); which perpendicular is altered in length when we put — hx for 8,r, leaving 83/ and 82 unal- tered ; and this is fatal to Professor Kelland's reasoning. 8 Park Terrace, Cambridge, June 7, 1842. P.S. Oct. 7, 1842.— Professor Kelland evidently does not suppose the axis of y to coincide with the direction of trans- mission: for suppose that it does, then lp = 8^, and there- fore equating the two expressions which Professor Kelland assumes to be equal to w2 at the foot of page 162, we have, vF(rK 2 • ohZy - F (r) s 9 . 2#8y 2 — — 8 x* sin2— ■— = Z, — « 8 w9 sin2 -—■ ; r 2 r . ■ 2 or, retaining only the first power of k\ 2^8tf28v2 = 2Z^-8y. A* - R. fr Fig. 2. \ffltrmt/'i/imti.";i!!ir;:«uiiaari dant) J 50- 100- The last specimen is evidently older and in a more advanced state of decomposition than the other ; its odour is far less powerful and offensive ; it contains little or no uric acid, but a larger proportion of inorganic substances*. It is difficult to imagine a manure better fitted for almost uni- versal use than this " guano ; " it contains in a highly concentrated form everything that plants require for their sustenance, with the exception perhaps of potash, which however is often abundantly supplied by a soil poor in other respects. The presence of a large quantity of oxalate of ammonia is a cu- rious fact, and was early noticed ; there can be no doubt that this substance owes its existence in some way or other to the uric acid contained in the excrement of the sea-birds, to the decomposition of which the guano-deposits are due. We can easily imagine that in this mass of putrefying substance, kept in a moistened state by the dews of night, a decomposition of a peculiar kind may be set up in the uric acid, and its gradual conversion into new products, among [* On the composition of guano, see also Phil. Mag., S. 3. vol. xix. p. 49.] Mr. Cock on Artificial XJranite. 387 which may easily he oxalate of ammonia, effected perhaps somewhat after the following fashion : — Uric acid C5 H2 N2 03 1 C 2 eq. oxal. acid C4 06 4 eq. water H4 04 > = < 2 . . ammonia H6 N2 1 eq. oxyg. from air O J Ll .. carb.acidC 02 CsH6Ns08 C5H6N208 This view, it must be remembered, is merely hypothetical, yet is borne out by the facts. The only case in which oxalic acid is known to arise from uric acid, is in the artificial formation of allantoin discovered by Liebig, and in which uric acid, water and peroxide of lead being boiled together, give rise to oxalate of the protoxide of lead, allantoin and urea ; it is in short an oxidizing action, so far resembling the one imagined, but more complex. Uric acid (doubled) C10 H4 N4 06 ] f Allantoin. . . . C4 H3 N2 03 3 eq. water Hg 03 > = I Urea C2 H4 N2 02 2. . ox. fromperox. 02J (^2 eq. oxal. acid C4 06 C10H7N4On C10H7N4Ou It is very unlikely that this peculiar mode of decomposition should occur under the circumstances in which the guano is pro- duced ; urea certainly would not resist destruction a week, and no doubt the allantoin would share the same fate. It was thought worth while nevertheless to examine one of the specimens (No. 1) carefully for these two bodies, a portion of the substance being acted upon by hot water, and the filtered solution cautiously evaporated to a small bulk, whereupon crystals were abundantly formed on cooling. These being dissolved in hot water, decolorized with animal charcoal, and the solution once more con- centrated, a second crop was got, but slightly coloured. These however turned out on examination to be nothing but oxalate of ammonia. The search for urea was equally unsuccessful. There is a curious relationship between the three bodies, oxalate of ammonia, oxamide and allantoin, the only difference in compo- sition being the diminishing proportion of the elements of water. Anhydrous oxalate of ammonia (doubled) . . C4 H6 N2 06 Oxamide (doubled) C4 H4 N2 04 Allantoin C4 H3 N2 03 " On the production of Artificial Uranite," by W. J. Cock, Esq. The subject of the present communication was observed during the preparation of the oxide of uranium from its mineral, Pitchblende ; it was obtained as follows : — The mineral was pulverized and well calcined ; it was then di- gested with diluted nitric acid, which dissolved the greater part of the soluble contents. (From this solution none of the precipitate was obtained.) The undissolved residuum was washed and dried, and again cal- cined. It was digested in nitric acid rather stronger than before, 388 Chemical Society. and gave a solution of a darker green than the first. This solution was left several weeks in open vessels, and upon its being drawn off, a quantity of the green precipitate was found adhering to the bottom and sides of the vessels. The composition, which is very variable, of the mineral Pitchblende, as given by Berthier in his Traitd des Essais par la voie seche from two analyses, is in the 100 parts, — Protoxide of uranium 51'6 60*0 Carbonate of magnesia 3*3 Peroxide of iron 7*2 2*5 Alumina (clay) 17*2 9-0 Sulphuret of iron and copper 1*2 5*5 Arsenical pyrites (iron) 5-8 9*2 Sulphuret of lead 6*0 3*5 Sulphuret of zinc , . . . 1*4 Carbonate of lime 2*2 2'2 Water and bitumen 4*2 5*2 98-7 98-5 No mention is here made of the phosphoric acid which enters into the composition of the artificial uranite. The composition of the na- tive uranite, as also of the double phosphate of uranium and copper (chalkolite), are thus given by Berzelius : — Uranite. Chalkolite. Oxide of uranium 59'37 60-25 Lime i 5-65 Oxide of copper 8'44 Barytes 1*51 Magnesia and oxide of manganese '19 Phosphoric acid 14'63 15*56 Water 14'90 15*05 Gangue 285 '70 Fluoric acid and oxide of tin ... . trace 9910 lOO* It appears that these two minerals are found mixed together in all proportions, and from the artificial compound which forms the sub- ject of the present notice, containing both oxide of copper and lime, that it is also a mixture of these salts. The following analysis of the " Artificial Uranite," made under the superintendence of Mr. Parnell, was read as an appendix to the above j — Phosphate of uranium 49* Oxide of copper 19*5 Lime 1*8 Water 21*5 Phosphoric acid in combination with"! „ „ oxide of copper and lime (loss) . . . . / 100-00 The process of analysis was the following : — (1.) Having previously ascertained by a qualitative analysis that Royal Irish Academy. 389 the sole constituents of the substance are phosphoric acid, peroxide of uranium, oxide of copper, lime and water, a known weight was dissolved in hydrochloric acid, and copper was precipitated as sul- phuret by transmitting sulphuretted hydrogen gas through the solu- tion. The precipitated sulphuret, when filtered and washed, was digested in nitric acid, and from the solution thus obtained, oxide of copper was precipitated by potash, washed, ignited and weighed. (2.) The solution, separated by filtration from the sulphuret of copper, was next evaporated to dryness and mixed with a little con- centrated sulphuric acid to convert phosphate of lime into sulphate, the mixture was diluted with alcohol, in which sulphate of lime is quite insoluble, and filtered. The sulphate of lime was washed with alcohol, dried, ignited and weighed. (3.) The filtered alcoholic solution, containing phosphate of ura- nium dissolved in the excess of sulphuric acid, was evaporated to dryness, the residue digested in nitric acid, and phosphate of ura- nium precipitated from the acid solution by ammonia. This, when washed and dried, was gently ignited and weighed. (4.) The water contained in the substance was determined by ob- serving what loss in weight it sustained when calcined at a dull red heat ; and (5.) The remaining ingredient, the phosphoric acid in combina- tion with oxide of copper and lime, was considered as the deficiency on the weight of the original substance. " Some additional Observations on the Red Oxalate of Chro- mium and Potash," by Robert Warington, Esq. This paper has been inserted in the present volume, p. 201. ROYAL IRISH ACADEMY. [Continued from p. 233.] May 24, 1841 (Continued).— The following Note "On the Force of aqueous Vapour within the Range of atmospheric Temperature," was read by James Apjohn, M.D., M.R.I. A., Professor of Chemistry in the Royal College of Surgeons. Having had it in contemplation some time since to investigate by means of an indirect, but I believe a very accurate process, the ca- loric of elasticity of the vapours of several liquids, I found myself stopped on the threshold of the inquiry by a want of knowledge of the tension of such vapours at different temperatures ; for, with the exception of the vapours of water, alcohol, aether, and oil of turpen- tine, the tension of no others had been made the subject of experi- ment ; and even in the case of the fluids just named, the results re- corded in the books appeared to me very far from being of such a nature as to preclude the necessity of further research. The method which I intended to employ, in order to arrive at the latent heats of vapours, not requiring a knowledge of their tensions beyond the range of atmospheric temperature, it occurred to me, that the necessary data for the solution of the preliminary problem might be obtained with facility, and, at the same time, with much precision, in the following manner : — 890 Royal Irish Academy : Dr. Apjohn on the Let a known volume of dry air be charged with moisture at any given temperature, and let the expansion produced by the moisture be accurately noted. The pressure being also measured by an ac- curate barometer, we have the means of calculating the force of the vapour which has produced the expansion. For if v be the volume of the dry air, and v' that of same air when charged with moisture, / the force of the vapour, and p the existing atmospheric pressure, we shall have from which we deduce v' = v x — , P-f f=m**- It was not my original intention to make any experiments upon the force of aqueous vapour, believing the table which I have hitherto employed, and which was calculated by the author of the article " Hygrometry," in Brewster's Encyclopaedia, from the experiments of Dalton, to have been sufficiently exact. But the correctness of this table having been indirectly called in question by sk> high an authority as M. Kupffer, who has come to the conclusion, that the table of the force of aqueous vapour, given by a German meteorologist of the name of Kamtz, is alone to be relied upon, I resolved to com- mence with the vapour of water, in the hope that I might be able, by the results of direct experiment, to corroborate a conclusion pre- viously drawn by Professor Lloyd, from a discussion of some hygro- metrical observations of mine, viz. that for temperatures within the atmospheric range, the table of Kamtz is less accurate than that of Dalton, the values given in the former being all too low. The apparatus I have employed in my experiments is composed of a glass ball prolonged on the one side into a short tube, furnished with a cap and stop-cock, and, on the other, into a long tube of somewhat smaller diameter, divided into 100 equal parts, each being •042 of a cubic inch, or the -001 of the total capacity of ball and tubes down as far as the division marked 1000. The first step consisted in filling this vessel with dry air, which was done in the following manner : into the extremity of the gra- duated tubular portion, a cork pierced by a small tube, open at both ends, was inserted, and this tube was then connected with the orifice of a table air-pump usually occupied by a syphon gauge. The stop- cock was now connected with one end of a long tube, packed with fragments of fused caustic potash, while the other end of this tube was attached by means of a slip of caoutchouc to a second tube passing through an air-tight cork fixed in one of the mouths of the bottle, at present used for the inhalation of chlorine. This bottle being charged with oil of vitriol, and the orifice of the plate of the pump being closed, the pump was worked, and a current of air was thus drawn through the glass vessel for about fifteen minutes, which in passing through the oil of vitriol, and over the fused potash, was deprived of all hygrometric moisture. The included air being now Farce of Aqueous Vapour at Atmospheric Temperatures. 391 absolutely dry, the stop-cock was closed, and the small tube connect- ing the air vessel with the pump having been drawn out in the mid- dle, and sealed hermetically by means of a spirit lamp, the air ap- paratus was separated from the potash tube, and transferred to a tall jar containing mercury, after which the sealed end of the small glass tube was broken beneath the surface of the quicksilver. The ap- paratus, however, being now completely filled, it became necessary to remove some of the air, and this was done by opening the stop- cock very gradually, care being taken that during this manipulation the external mercury should be higher than its level within the tu- bular portion. The entire was then placed in a small room, the temperature of which was found not to vary more than one degree Fahrenheit during the twenty-four hours, the stop-cock having been first attached to one extremity of a string, which was carried over a fixed pulley placed in the ceiling, and whose other end carried a counterpoise by which the air vessel was kept in a vertical position, and the observer was enabled readily to bring the mercury within and without to the same level, before he registered the volume of the included air. On the next day, after the apparatus was mounted, and the four following ones, the volume of the dry air, its temperature, and the existing pressure were accurately noted. This pressure, which was measured by a portable barometer of Newman's, having undergone a variety of corrections, for the capacity of the cistern compared to that of the tube, for the excess of the temperature of the quicksilver over 32°, for capillarity, and for a constant error by which I found my barometer affected, when compared with the standard instru- ment in the Observatory of Trinity College, I reduced by calculation in each instance the observed volume of air to what it would be at 32°, and under a pressure of 30, using for the expansion of air the corrected coefficient ^^, which has resulted from the experiments of Rudberg, and thus obtained the following numbers, which, it will be observed, differ very little from each other : — 1 911-11 2 911-85 3 910-21 4 913-30 5 911-72 911*64, therefore, the mean of the five observations, may be as- sumed as the true volume of the included dry air, at 32°, and under a pressure of 30. The volume of the dry air being determined, the next step was to charge it with moisture. In order to accomplish this, the air vessel was lifted by means of the string, so as that the mercury within should be about an inch higher than the external mercury, and distilled water was then poured into the upper cavity of the stop- cock, so as completely to fill it. The stop-cock was now cautiously turned, so as to admit the entrance of the moisture guttatim • and more water being occasionally poured on, this manipulation was repeated until the mercury within came to be covered by a film of water of about one- 392 Royal Irish Academy : Dr. Apjohn on the tenth of an inch in thickness. The stop-cock was now closed, and the apparatus being lowered, the whole was left to itself until the following day, when the first of a series of observations, continued for twenty successive days, was made, each comprehending the vo- lume of the moist air, the pressure, and the temperature both of the air and of the mercury in the barometer. To deduce from these by the formula / = X p, the force of vapour, it was necessary, in the first instance, to apply to p all the corrections already ex- plained, and in addition to raise 91T64, the volume of the dry air, to what it would be at the temperature and pressure of the moist air, as noted in each observation. But, as this involved tedious arithmetical computations, and as the thermometer during the per- formance of the twenty experiments varied only about 15°, I came to the resolution, being at the time upon the eve of leaving town for a couple of months, to postpone the calculations until I should be possessed of data applicable to the solution of the problem I had un- dertaken, throughout a more extended range of temperature. Accordingly, in November last, I resumed the subject with the very same apparatus, which had been left statu quo in the interval, and succeeded in completing a series of forty-five additional observa- tions, extending nearly as low as 32°, and which I had every reason to expect would lead to satisfactory results. Upon, however, sub- mitting the whole to calculation, I have been led to the mortifying conviction, that in consequence either of the absorption of the oxygen by the mercury and brass-work, or some accident which befel the apparatus during my absence from town, the entire of the latter series of observations is of no value, as they lead to results for the force of aqueous vapour, which are certainly greatly below the truth. Upon the present occasion, therefore, I can direct attention only to the observations made in July and August last. These are contained in the following table, and, as has been already stated, they amount to twenty in number, the highest temperature having been 65°, and the lowest 490,6. The numbers in the last column represent the bulks which the 911*64 volumes of dry air would have, if reduced to the temperature t, and the corrected pressure p. Table I. Tempera- 911-64 re- v'. t. p observed. ture of barometer. p corrected. duced to t and p corrected. 1001 60-4 1 29'450 59-9 29-430 982-82 1001-5 59-8 29-364 60-1 29-338 984-77 997 60 29-548 60 29-524 978-94 984 59-1 29-822 59-5 29-807 967-97 977 58-4 29-980 58-6 29-971 961-38 984 58-4 29-780 58-9 29-767 967-97 991 59 29-624 59-4 29-607 974-33 Force of Aqueous Vapour at Atmospheric Temperatures. 393 Table (continued). Tempera- 911-64 re- t/. t. p observed. ture of barometer. p corrected. duced to t and p corrected. 983-5 59-4 29-862 59-8 29-847 967-23 979-5 60-2 30-100 60-6 30-086 962-69 977-5 61-2 30-132 61-3 30-165 960-35 983 61-6 30-05 62-2 30-037 965-18 973-3 62-2 30-230 62-4 30-212 960-69 978-4 61-6 30-214 62-2 30-197 960-06 983-5 63-1 30-156 63-6 30-131 964-93 987-5 64-3 30-130 64-7 30-104 968-01 991 64-1 30-032 64-6 30-005 970-83 994-5 64-8 29-989 65 29-961 973-55 994-5 65 29*972 66 29-940 974-61 989 65-2 30-152 66-5 30-120 969-12 1000 64-8 29-834 65 29-306 978-62 From the first, last, and second last columns of the preceding table, the force of aqueous vapour has been calculated in the manner already explained. The values thus obtained are exhibited in the second column of Table II. Column 1 contains the temperatures ; column 3 the tensions, as deduced from Dalton's experiments ; and column 4 the same as given by Kamtz. Table II. 1. 2. 3. 4. Dalton. Kamtz. 60-4 •5345 •5302 •5125 59-2 •4908 •5197 •5023 60- •5348 •5232 •5061 59-1 •4855 •5077 •4893 58-4 •4917 •4960 •4768 58-4 •4849 •4960 •4768 59- •4980 •5060 •4875 59-4 •4937 •5128 •4949 60-2 •5169 •5265 •5093 61-2 •5292 •5444 •5261 61-6 •5445 •5517 •5343 62-2 •5412 •5628 •5458 61-6 •5660 •5517 •5343 63-1 •5689 •5798 •5615 64-3 •5941 •6033 •5860 64-1 •6107 •5993 •5824 64-8 •6311 •6133 •5949 65- •5988 •6173 •5985 65-2 •6054 •6214 •6029 64-8 •6372 •6133 •5949 Phil. Mag. S. 3. Vol. 21. No. 139. Nov. 1842. 2 D 394- Royal Irish Academy. When the corresponding numbers in the three columns are com- pared, it will be at once observed, that the values of f, investigated by the method just explained, are somewhat less than those extracted from the table I have been hitherto in the habit of using ; but that they are considerably greater than the values of Kamtz, the differ- ences being generally better than twice as great in the latter in- stance as in the former. This will be more manifest by taking a mean of the different results in column 2, and comparing it with the force of vapour corresponding to the same temperature as given in the two other tables. Now, the mean of the temperatures is 61°'63, the quotient got by dividing their sum by twenty. But the corre- sponding mean value of /, in column 2, must be differently calcu- lated, seeing that the temperature and the corresponding tensions of the vapour augment at a very different rate. For temperatures, in fact, in arithmetic progression, the corresponding tensions are in geometric progression, and, although this is well known to be but an approximate law, it may be considered as rigorously true for the limit- ed range of temperature within which my experiments have been made. To calculate, therefore, the mean force of vapour, as deducible from the numbers in column 2, and which must correspond to the tempe- rature 610,63, it is only necessary to add together the logarithms of the numbers in this column, and divide their sum by twenty, and the quotient will be the logarithm of the mean. When this process is gone through, the mean logarithm is found to be "73699, and the corresponding number *54575. The following, therefore, are the tensions of aqueous vapour at 610-63, as deduced from my experi- ments, and as extracted from the tables of Dal ton and Kamtz. My experiments. Dalton. Kamtz. 61°'63 -5457 '5523 '5349 Difference between Dalton's number and mine = + "0066 Difference between Dalton's number and that of Kamtz = + '0174. It thus appears, that the result at which I have arrived is some- what less than the Daltonian number, but considerably greater than that given by Kamtz ; and that, therefore, my experiments, as far as they have been discussed, give at least a. prima facie countenance to the opinion, that the values of the elastic force of aqueous vapour, as given by the latter philosopher, are, at and about 610-63, below the truth. Before, however, this conclusion can be considered as fully esta- blished, and before we can judge correctly of the amount of the errors by which his table is affected, it will be necessary to inquire whether the thermometer I have employed be a true one. This essential inquiry I have been enabled to institute by my friend Pro- fessor Lloyd, who has put into my possession, for the purpose, a thermometer given him by Professor John Phillips, together with a table of differences between it and the standard thermometer belong- ing to the Royal Society. Upon a comparison of the two instru- ments, I find, that at and about 60°, the thermometer I have em- ployed stands *6 of a degree higher than that lent me by Professor Lloyd, while the latter stands *3 of a degree higher than the standard in possession of the Royal Society ; so that the indications of my Royal Irish Academy. 395 instrument are at 60o,9-10ths of a degree higher than the truth. If such he the case, *5457, instead of being the force of vapour at 61°-63, is the force at 6T63 — 0*9 = 60°73 ; and to compare the result of my experiments with the tables of Dalton and Kiimtz, it is only necessary to extract from these the values of the force of vapour corresponding to the temperature 60°* 73. My experiments. Dalton. Kamtz. 60°-73 -5457 "5361 -5157 Difference between Dalton's number and mine — "0096. Difference between Dalton's^ number and that of Kamtz . 4- *0184. The consideration, therefore, of the error of my thermometer, and the allowance made for it, only strengthens the conclusion already arrived at ; and I do not now feel any difficulty in giving it as my deliberate opinion, that the table of the force of vapour given by Kamtz is, within the atmospheric range of temperature, erroneous, his values being all too low. June 14, 1841.— The Rev. H. Lloyd, V.P. read a "Note on the mode of observing the vibrating Magnet, so as to eliminate the Effect of the Vibration." The following modification of one of the methods proposed by Gauss for the attainment of this end, appears to combine the greatest number of advantages ; namely, to take three readings, at the times. t — T, t, t+T; t being the epoch for which the position of the magnet is desired, and T its time for vibration*. In order to show that this method is ade- quate, it is necessary to deduce the equation of motion of a vibrating magnet in a retarding medium. Let X denote the horizontal part of the earth's magnetic force ; q the quantity of free magnetism in the unit of volume of the sus- pended magnet, at the distance r from the centre of rotation ; and 9 the deviation of the magnet from its mean position. The moment of the force exerted by the earth on the element of the mass, dm, is X q r d m sin 0 ; and the sum of the moments of the forces exerted upon the entire magnet is X jW/ sin 0 ; where jo, denotes the value of the integral fq r d m, taken between the limits r — + I, 2 I being the length of the magnet. Again, the velocity being small, the resistance may be assumed to be proportional to the velocity. Accordingly, if ca denote the angular velocity, the retarding force due to resistance, upon any element of the surface, d s, at the distance r from the centre of motion, is — Kdsrw; and the entire EAoment of this force upon the whole magnet is Ku>fr*ds=-Kuj rr*dm] * In practice, it is sufficient to take the nearest whole number of seconds for the value of T. 2D2 396 Royal Irish Academy. where H = — — The ratio H is constant for all bodies of pris- ds r matic form ; and for these, therefore, the moment of resistance is _MK H U'' M denoting the moment of inertia / r2 dm. The differential equation of motion is, therefore, dta Xu . a K — — = — -f- sin 9 to. dt M H rf 9 But w = — — - ; and, 0 being small, we may substitute 0 for sin 0. dt The equation thus becomes d^ + Kdj_ Xj, dt Hd*x M Making, for abridgement, — = 2 A, — |- = B-, the integral is 0 = (c cos V B2 — A3 . t + c' sin V B* — A2 . *) e~ A '. But, A being small, we have approximately e-A' = l-A*; and, if T denote the time of vibration, VBa-Aa.T = tf. Hence the preceding equation may be put under the form 0=(1 — A/) (ccosifL 4. c'sin*4Y Now, let 0, and 0' denote the values of 0, when t becomes / — T and t + T. It will be seen at once, on substitution, that 0, + 2 0 + 0' = 0. Hence by combining the three readings according to the preceding formula, the deviation of the magnet from its mean position, arising from the vibratory movement, is completely eliminated ; and it will readily appear that the same result may be attained by any greater number of readings, taken and combined according to the same law. Now, let the value of 0 contain an additional term, + p t, propor- tional to the time : or, in other words, let us suppose that there is a progressive change of the declination, which may be regarded as uniform during the whole interval of observation, "it is then mani- fest that 0/-J-20 + 0' = 4^f; and accordingly that the quantity £(0/ + 20 + 0') will give the mean place of the magnet corresponding to the epoch t. Royal Astronomical Society, 397 The supposition of a uniform change can, however, be regarded as an approximation to the truth, only when the interval of time be- tween the first and last reading is very small, in comparison with the interval between the successive maxima and minima, in the fluctua- tions of the irregular movement. Hence, we may conclude, that it is important, in the first place, to employ three readings in preference to any greater number ; and, secondly, that it is desirable that the time of vibration of the magnet itself should be as small as possible, consistently with the accuracy of its indications in other respects. ROYAL ASTRONOMICAL SOCIETY. [Continued from p. 61.] January 14, 1842. — I. Observations of Halley's Comet, made at the Observatory of Geneva in the years 1835 and 1836. By M. Miiller, under the direction of M. Gautier, Director of the Observatory. Com- municated by Sir J. F. W. Herschel, Bart. These observations were made on fifty-two nights, beginning with August 31, 1835, and ending with May 7, 1836 ; of which thirty- one were before the perihelion passage of the comet, and twenty- one after the passage. The instrument used is an equatoreal of Gambey, whose telescope has an object-glass of four French inches diameter, and of forty-two French inches focal length. The decli- nation circle and the hour circle of the instrument are each thirty inches in diameter ; the former being divided to every three minutes of a degree, and by means of its verniers giving arcs of 3" ; and the latter being divided in time, and by means of its verniers giving the fifth part of seconds of time. The times were taken with a clock by Lepaute, which was every evening compared with the transit clock. The index corrections, obtained chiefly by observations of stars found in the Astronomical Society's Catalogue, and whose observed places were compared with the places taken from that Catalogue, and from Pond's Catalogue of 1112 stars, were very consistent throughout the whole series of observations, and show that the firmness of the in- strument, as well as its state of adjustment, were highly satisfactory. Absolute observations of both elements were obtained in every in- stance by reading off both circles ; this method being preferred by M. Gautier to differential observations with a micrometer. A reticu- lar micrometer, made of fine plates of metal, was used, the faintness of the comet scarcely ever admitting of any illumination of the field. In the reduction of the observations, the mean refractions were computed for all the observations of the comet and the comparison- stars ; and the instrumental right ascensions and north polar di- stances are given, cleared of the effects of them. The index cor- rections obtained from all the observations of stars are also given. It is, however, left to those who may be desirous of using the ob- servations of the comet to apply them, and also the effects of paral- lax, to the observed places. The height of the observatory above the level of the sea (above 400 metres) caused the comet to be visible at this observatory longer than at most other places in Europe ; and the author hopes that the 398 Royal Astronomical Society. circumstance may render the latter part of the series especially valu- able, the southern position of the comet and the unfavourable state of the weather causing the observations of it to be in general very scarce, after its perihelion passage. II. Note on the Masses of Venus and Mercury. By R. W. Roth- man, Esq. The following is the conclusion of this note, the whole of which is given in the Society's Monthly Notices for January. On the whole, it is very remarkable that the planetary masses given in the Me'canique Celeste (vol. iii. p. 61), satisfy the secular motions affecting the orbit of Venus much better than the masses of later astronomers. It appears that in later times the mass of Mer- cury has been too much increased, and that of Venus too much di- minished. What has been previously remarked concerning the masses of Venus and Mercury is confirmed by the motion of the node of Mercury. If this motion be calculated by theory with the masses of the Mecanique Celeste, the result agrees almost exactly with the motion determined from observation by Lindenau. — See his Tabula Mercurii, p. 9. III. Observations of the Immersion of p1 Leonis behind the Dark Limb of the Moon. By R. Snow, Esq. The observed Ashurst sidereal time of the immersion was 15h 37m 23s* 9. The observation was made with a power of 75 on the telescope of the five-feet equatoreal, under very favourable circum- stances. IV. Extract of a letter from Professor Encke to Mr. Airy, dated 20th December, 1841. Translated from the German. Communicated by G. B. Airy, Esq. This communication will be found, entire, in the preceding volume, p. 137. V. Comparisons of the Planet Venus in Right Ascension and N. P. D. with the Star A. S. C. 423, made with the Equatoreal In- strument of the Observatory at Ashurst, on April 9, 1841. By R. Snow, Esq. The equatoreal instrument employed for these observations is of Fraunhofer's construction, and furnished with clockwork ; the ob- ject-glass is of five feet focal length, and of four inches aperture. It is supported on a Very firm pier, and retains its position very well. The observations were made with a position micrometer, adjusted for transit and declination observations. They consist of thirty transits of the star and of the first limb of Venus over the meridian wire, and of nine micrometrical measures of the differences of N. P. D. of the star and the south limb of the planet : the corrected sidereal times of the observations are given. The value of a revolution of the micrometer-screw had been de- termined by 400 transits of stars near the equator. Measures of the semidiameter of Venus were made at the same time, by which it was found that the measured value exceeded the tabular value given in the Nautical Almanac by 8**1. The circumstances of the observations were favourable. VI. Reduction of Mr. Snow's Observations of Venus and the Star A. S. C. 423, with some remarks upon the employment of equa- Royal Astronomical Society. 399 toreals in Planetary Observations. By the Rev. Richard Sheep- shanks. Mr. Snow's observations admitted of being so grouped as to fur- nish four sets of comparisons in right ascension and five sets in de- clination. The effects of parallax and refraction were computed by the formulae used at Greenwich (Greenwich Observations, 1836, pages lxiv. and lxv.). The right ascension of the star was taken from Lord Wrottesley's Catalogue, the declination from the Astro- nomical Society's Catalogue, and the semidiameter of Venus from Mr. Snow's Observations ; and thus the right ascension and declina- tion of the pJanet were obtained for the Ashurst sidereal times of observation and compared with the places interpolated from the Nautical Almanac for the same times. The resulting corrections to be applied to the right ascensions and declinations of the Nautical Almanac are as follow : — Right Ascension. Declination. — 1*10 from 15 obs. + 3*1 from 1 obs. -1*32 ... 5 ... + 5-4 ... 1 ... -1-25 ... 5 ... + 5-3 ... 4 ... -1-27 ... 5 ... +5-2 ... 2 ... + 3-6 ... 1 ... — 1-19 ... 30 .. . + 4-9 ... 9 .— The mean epoch is about 8h 30m Greenwich mean solar time. The author remarks generally with respect to the treatment of such observations, that they may be boldly grouped without sensible error, so as to make one reduction serve for a considerable number of observations ; and that to ensure the greatest facility for group- ing, the observations of one element (if both cannot be made simul- taneously) should be repeated several times as rapidly as possible alternately with similar sets of observations of the other element. "With respect to the value of such observations, the results above given will show that an equatoreal, when thus used, is no mean rival to meridian instruments. The star can be subsequently determined with any required degree of accuracy, and the observations can be made with as great freedom from constant error with an equatoreal as in the meridian. In this latter respect, indeed, the power of re- petition gives to the equatoreal a great superiority, and may be made to counterbalance the disadvantages arising from want of steadiness. The last-named quality can, however, in most instances, be obtained in as great a degree as is requisite. The hour-circle being firmly clamped, if the instrument be well balanced, sudden changes can arise only from careless handling. The supposed uncertainty and instability of the adjustments are probably the principal obstacle to the free use of equatoreals in En- gland ; but the author considers that most equatoreals can be ad- justed very nearly, and that when ordinary care has been taken, the position remains sufficiently permanent ; and it is certain that when rationally used, the effect of any unavoidable derangement is so nearly annihilated as to be quite insensible. The difficulty of performing 400 Royal Astronomical Society. the adjustments of an equatoreal is very trifling, if it be methodically undertaken, and the residual errors much smaller than would at first sight seem possible. With well-turned collars and pivots an error of half a minute, arising from flexure or other causes, must be looked upon as an impossible quantity, in which case the differential effects upon objects in the zodiac might be disregarded. With respect to methods of observing, the author recommends that the telescope be moved in declination like a transit, in order that the star and planet may pass over the same part of the wire. In this case reliance is placed only on the adjustment of the cross-axis ; but when the de- clination is not changed, it is presumed that the position of the wire is correct ; and this can be ascertained with only a moderate degree of certainty. In equatoreals which can be reversed in every position, the observations should be made, one group in one position, and the second in the position reversed. The best wiring for such observa- tions, the author considers to consist of three, five, or seven im- movable wires, at equal distances, and parallel to the meridian, transit- wires, in fact, and seven equidistant wires at right angles to these, at 5' interval, the plate which carries the latter wires being moved by a micrometer-screw. The advantages of this system are a saving of time in screwing the micrometer, less wear of the screw, and less dependence on it for large intervals. Thus far it has been shown, that an equatoreal instrument may be made to rival meridian instruments, by the bestowal of a little more time and trouble ; there are, however, many cases where the equatoreal is more convenient, and many where it can, and the others cannot be used. A planet which comes to the meridian at a late or inconvenient hour of the night may be observed several hours earlier with the equatoreal. In so variable a climate as ours, it is not too much to say, that the number of good planetary observations might be thus very much increased ; and if an equatoreal were steadily directed to this object in the southern hemisphere, to meet the case where the planet has considerable south declination, we should soon have the materials by which the present sufficiency of theory might be satis- factorily tested. The superior planets cannot always be observed in full daylight with large meridian instruments, yet equatoreals of even a small size might be made to determine their places with great accuracy after sunset. Again, large equatoreals, which are now tolerably abundant, might take charge of the minor planets. Micro- metrical observations only have been taken notice of in the prece- ding remarks, the divided circles of the instrument being considered only as finders, and for performing the adjustment, though in some instruments they are large and good enough to be used in differen- tial observations. Still the proper use of the equatoreal is the as- certaining of small differences by means of the micrometer and time. In conducting the observations, the author recommends that there should be made each night two or three transits of the star of com- parison, and of two other stars, one above and one below it a few Institution of Civil Engineers. 401 degrees, the instrument being clamped in right ascension, by which means it would be made evident whether the derangement of the adjustment had any sensible effect upon the place of the planet. It is the want of observations to accuse derangement which makes the stars observed as moon-culminators less satisfactory than if they were more widely spread in declination. With respect to observations of the moon, the author mentions one set, originally suggested by Struve, but never carried into effect. There are three observations which might be made when a bright star is occulted by or reappears from under the moon's bright limb : — 1 . The time of disappearance or reappearance of the, star. 2. Micrometrical measures of distance between the star and the moon's bright limb, the clock-work and the wire micrometer with the slipping piece being used. [This is the common observation of distance, and might be use- fully applied to the case of a near approach.] 3. Differences of right ascension between the moon and star, the hour-circle being clamped as in ordinary transit observations. If the place of the moon be computed from these three observa- tions, we ought to arrive at the same result ; and if we do not, the difference between the first and second result arises from the moon's irradiation, and will give a measure of it ; also a difference between the second and third results would show some error in the mode of taking the transit of the moon's limb, which is at present rather a doubtful point in practical astronomy. If by certain corrections, constant either to the observer or the telescope, these results can be made to agree in each case, and always the longitude might be determined in a shorter period, though with more calculation than at present, and a greater certainty be obtained from transits of the moon's limb. In conclusion, the author hopes that the attention of persons who possess good equatoreals may be directed to the planets whenever those bodies are favourably situated with respect to an observable star. The adjustment is really nothing, and if pairs of stars above and below be observed, any error arising from mal-adjustment can be ascertained and allowed for. The artist will take care, if warned, that the cross-axis shall be at right angles to the polar axis, and the reductions, in ordinary cases, are very trifling, especially if by ju- dicious grouping one reduction is made to serve for several observa- tions. INSTITUTION OF CIVIL ENGINEERS. May 3, 1842. — " Description -of the Tunnels, situated between Bristol arid Bath, on the Great Western Railway, with the methods adopted for executing the works." By Charles Nixon, Assoc. Inst. C.E. The works described in this paper comprised a large quantity of heavy earth- work in tunnels, &c. ; they were commenced in the spring of the year 1836, and terminated in the year 1840. The whole of 402 Institution of Civil Engineers. the tunnels are 30 feet in height from the line of rails, and 30 feet in width ; they are curved to a radius of about 1 20 chains ; the gradient of that part of the line is four feet per mile. The strata through which they were driven consisted generally of hard gray sandstone and shale, with the gray and dun shiver, &c. ; in a few places only, the new red sandstone and red marl were traversed. Every precaution was taken for securing the roofs, by lining them with masonry where the nature] of the strata demanded it, and in some places invert arches were turned beneath. Driftways were driven before the tunnels were commenced, and shafts were sunk to enable the work to proceed at several points simultaneously. The modes of conducting the works by these means are fully described, with all the difficulties that were encountered. The construction of the centres is given, with the manner of lining the arches with masonry, which is stated to be what was termed " coursed rubble;" but was of a very superior description, and in every respect similar to ashlar- work. The author offers some remarks with regard to the expense of working tunnels by means of centre driftways. He states this plan to be costly, and in many instances without corresponding advan- tages, on account of the difficulty of keeping the road clear for the waggons. He recommends that when driftways are used they should be on the lower side of the dip of the strata, as the excavation would be facilitated, and the road would be kept clearer. In long tunnels he has found the cheapest and most expeditious mode of working to be by excavating the centre part from shafts, and both the ends (together if possible) from the extremities after the open cuttings are made. The drawing accompanying the paper gave a longitu- dinal section of all the tunnels, and showed to an enlarged scale several transverse sections of them, where the variations of the strata rendered either partial or entire lining necessary. In answer to questions from Mr. Vignoles and other members, Mr. Nixon explained that the extra number of shafts had been re- quired in order to enable the works to be completed within a given time : there had not been any accidents during his superintendence, but subsequently one of the shafts had collapsed. The cost of driving the driftways, the dimensions of which were 7 feet wide by 8 feet high, was ten guineas per yard lineal. He then described more fully his proposed plan of cutting the driftways on the lower side, instead of the centre of the tunnel, and stated the advantages chiefly to consist of a saving in labour and gunpowder, as a small charge sufficed to lift a considerable mass of rock when acting from the dip : the road was also less liable to be closed by the materials falling into it when the enlarged excavation proceeded from one side instead of upon both sides. Dr. Buckland, after returning thanks for his election as an hono- rary member of the Institution, expressed his gratification at the prospect of a more intimate union between engineering and geology, which could not fail to be mutually beneficial, and cited examples of this useful oo-operation in the cases of railway sections, and Institution of Civil Engineers. 403 models that had recently been furnished by engineers to the Museum of (Economic Geology. He then proceeded to remark upon the geological features of the South- Western Coal-Field near Bristol and Bath, which had been described by Mr. Conybeare and himself, in the Transactions of the Geological Society of London (1824). Some of the tunnels near Bristol are driven in the Pennant grit of the coal formation, where it is thrown up at a considerable angle, and composed of strata yielding slabs and blocks of hard sandstone used extensively for pavement. In traversing such inclined and dislocated strata, the engineer's attention should, he conceived, be especially directed to the original joints that intersect the beds nearly at right angles to their planes of stratification, and also to the fractures produced during the move- ments they have undergone. These natural divisions and partings render such inclined stratified rocks unworthy of confidence in the roof of any large tunnel, and liable to have masses suddenly de- tached. Inclined strata of a similar sandstone are perforated by many tun- nels on the railway near Liege, in nearly all of which the roofs are supported by brick arches. It has been found impossible to make the tunnels through lias and red marl without continuous arches of masonry. In any of the tunnels which have been carried through strata of the great oolite, the parts left unsupported by masonry would, in his opinion, be peculiarly liable to danger, because even the most com- pact beds of oolite are intersected at irregular intervals by loose joints at right angles to the planes of the strata, and occasionally by open cracks : and it is to be feared that the vibration caused by the rail- way carriages would tend eventually to loosen and detach these masses of stone. ' He apprehended still greater danger would exist in tunnels cut through the loosely joined strata of chalk, unless they are lined throughout with strong masonry ; and even that, in a recent case, had been burst through by the weight of the incumbent loose chalk coming suddenly upon the arch. In open cuttings through chalk, where the numerous interstices and the absence of alternating clay-beds prevent any accumulation of water, there is little chance of such frequent landslips as occur where beds of stone, gravel, or sand rest on beds of clay ; but until the side walls of chalk are reduced to a slope at which grass will grow, they will be subject to continual crumblings and the falling down of small fragments, severed by the continual expansion and contraction of the chalk, under the destructive force of atmospheric agents, and chiefly of frost. In open cuttings, where the inclination of the strata is towards the line of rails, the slope should be made at a greater angle than if the strata incline from the rails ; if this be done, fewer landslips will occur from accumulations of water between the strata thus inclined towards the rails ; and such sjips may be further guarded against by 4 04 London Electrical Society. minute and careful observation of the nature of the individual strata, and a scientific application of subterranean drains at the contact of each permeable stratum with a subjacent bed of clay. Tunnels can be safely formed without masonry in unstratified rocks of hard granite, porphyry, trap, &c, and in compact slate rocks ; also in masses of tufa, such as cover Herculaneum, and are pierced by the grotto of Pausilippo near Naples ; but, in his opinion, wide tunnels driven in stratified rock could not be considered secure unless they were supported by arches. Mr. Sopwith confirmed the remarks on the importance to the civil engineer of a knowledge of the geological character of the strata through which tunnels or open cuttings were to be made : the cost was materially affected, as well as the stability of the works. The angle of inclination and the lines of cleavage should be carefully studied : on one side of a cutting the slope might be left steep, and all would be firm and dry ; whilst on the other, if the same slope was adopted, all would appear disintegrated and wet, and a series of accidents would be the necessary consequence. He could not suffi- ciently urge the importance of a more intimate connexion between the geologist and the engineer. LONDON ELECTRICAL SOCIETY. [Continued from p. 313.] Oct. 18, 1842. — The Chairman announced that Walter Hawkins, Esq., M.E.S., F.Z.S., &c, had presented the Society with a third spe- cimen of the Gymnotus Electricus ; but which, like the two former, has not survived the voyage. It is now undergoing dissection, the re- sult of which will be laid before the Society. Mr. Hawkins intends persevering until he succeeds in his desire to present a living speci- men to the Society. A letter to the Secretary from Mr. Phillips, M.E.S., was read, con- taining " the particulars of a fatal accident by lightning at Se- Blazey ." Some children had taken refuge from a storm in a toll-house, near which was an elevated crane, and also a comparatively lofty house. The electric matter discharged itself, not on either of these (apparently) better objects, but burst upon the low hut, and in its passage to the earth killed two of the children, and hurt others. From the draw- ing which accompanied this letter, it appears that the toll-house was immediately at the edge of a rivulet. The lightning divided itself in its passage down the house, first entering by the soot of the chimney. The letter also contains an account of the damage done to a ship at Par by the same storm. The top-mast was shattered to pieces ; a large piece was knocked out of the lower part of the main- mast ; the rupture occurred exactly at the termination of a chain hanging from the cross-trees, the said chain having protected the upper portion of the same mast. Several men were knocked down. The crew spoke of a suffocating smell of sulphur. A translation, by Mr. "Walker, Hon. Sec, of M. Becquerel's first observation " On the Electro-Chemical Properties of Simple Bodies, and on their application to the Arts," was then read. The author Notices respecting New Books. 405 speaks of electro-chemistry as being " a bond between physics and chemistry." He says, that formerly our experiments were carried on by large, but now by small series of Volta's pairs, and thus are our operations easier of practice. He intends treating on all simple bodies, beginning with the metals, and of those with gold. He al- ludes to certain principles established in former papers, and pur- poses showing the application of electro-chemistry to the arts, as in assaying, gilding, &c. He dwells in his introduction upon the che- mical theory, and adduces two important facts in confirmation of its truth ; — 1st, that there is no chemical action without a considerable disengagement of electricity ; 2nd, that a Volta's pile, charged with a liquid not acting chemically on either of the two elements of which each body is composed, does not become charged, that is, produces neither current nor electricity of tension. If one of the two ele- ments is attacked, even very feebly, by the liquid, the effects of cur- rent and those of tension immediately follow. As the chemical action increases, so do the electrical effects. He offers an observa- tion, due to his son Edward, which he considers of much weight in favour of this theory. "When one substance acts on another, under the influence of light, electrical effects are produced, as in all che- mical reactions, which effects are manifested so long as this influ- ence remains. If it ceases to exist, there is no longer any sign of electricity, and nevertheless the contact of the newly-formed sub- stances with the metallic plates, still exists, and nothing is changed in the circuit." He then introduces gold, its extraction from the ore, and the modes of assay, illustrated by several experiments "of his own upon the ores of the Oural and the Altai, in order to exa- mine the nature and extent of the stamping and washing best fitted to produce least waste. He then adverts to amalgamation, &c, and proceeds to the further execution of his task, at which point the present translation ceases, the remaining portion being reserved for a future meeting. An abstract of observations on the degree of identity between electrical and chemical affinity, by Mr. Prater, M.E.S., was read. Mr. Weekes's Electro-Meteorological Journal for September was laid before the Society. LXX. Notices respecting New Books. The Difficulties of Elementary Geometry, especially those which concern the Straight Line, the Plane, and the Theory of Parallels. By Francis William Newman, Tutor at Manchester College. Longmans. THE philosophy of our mathematical processes is far from being a favorite subject of investigation in this country ; though amongst the continental geometers it is cultivated with singular predilection. There are, however, two aspects under which this class of inquiries may be viewed ; or more properly, two distinct branches of the inquiry, which seem to require faculties of a consi- derably dissimilar kind. The first class is that in which the logical 406 Notices respecting New Books. character of the several methods is examined, in connexion with the phenomena of the human mind. The character of our first prin- ciples, and the logic of the early theorems of each branch of pure mathematics, are proposed by this class of philosophers as the im- mediate subjects of their investigation. The other class, and that the more influential and learned one, proposes to discover the influence of methods of research upon the progress of discovery, to classify our knowledge according to its bearing upon this one point, and to generalize, as far as possible, the isolated and incompletely connected propositions which are already known. Of this latter class M. Chasles is a splendid example ; and of the former, Mr. Newman is a very respectable and (which renders it of more value) a very useful one. The " off-handed " manner in which the fundamental principles of geometry are generally dismissed by systematic writers on the subject, is essential to the general style and objects with which such works are composed, namely, the most brief development of the greatest possible number of geometrical truths in a given space. Still, we think that the general purposes of mental culture would be better studied in making geometry merely one of the illustrations of the phenomena of mind : and in this Mr. Newman has evidently entertained the same views that we do, and as was so forcibly urgecj by that distinguished master of the philosophy of the human mind, Dugald Stewart ; though perhaps we differ from each of them, as they do from each other, on certain points brought under discussion. In a notice like the present, it would be impossible to give any idea of the details of the work. We would moreover remark, that to the discussion of the fundamental principles of the geometry of the school of Euclid our approbation and recommendation is mainly con- fined. When the author travels beyond these boundaries he is evi- dently " not at home," as his acquaintance with the higher branches of modern geometry is evidently very limited, and his criticisms, therefore, of little value. We can, however, with this reservation, and without pledging ourselves to the entire adoption of the author's views and reasonings, most cordially recommend the perusal of the book to the speculative geometer, and urge its careful study upon those who are engaged in teaching the elements of the science for the purpose of cultivating the faculties, rather than of " creating mathematicians by profession." Logarithmic and Trigonometric Tables, %c. London : Simpkin and Marshall, 1836. Six years ago a private gentleman residing in the country caused to be printed an edition of Hassler's Logarithmic Tables. By various causes the advertisement of this book was delayed, so that up to the present time it has remained altogether unknown, even to those who take pleasure in collecting and comparing tables. On these facts coming to the knowledge of the writer of this paragraph, he recommended that, considering the length of time which had elapsed, the work should not be brought into notice without some Intelligence and Miscellaneous Articles. 407 re-examination. In consequence of this recommendation, a well- practised computer in the Nautical Almanac Office was employed to read three thousand of the logarithms of numbers and eight degrees of the trigonometrical portion (all chosen at hazard), and compare them with tables of undoubted accuracy. The consequence was, the detection of only three errors, one in the numbers, two in the sines, &c. ; of these three there was only one which an expert user of the tables could not have detected at sight. This being considered, and also the number of errors which were detected in Hassler's book du- ring the printing, it is certain that the work before us must be very correct ; as correct, indeed, as any table is likely to be unless it have been first stereotyped and then re-examined, and much more so than most others of the same size. The work is an imitation of Hassler's, and has the same small oc- tavo form. All the logarithms are to seven decimals. The loga- rithms of numbers are as usual : in the trigonometrical portion the first and last five degrees are to every ten seconds, all the rest to every half minute, with differences for ten seconds annexed. In the first two degrees is added a factor for facilitating the determination of the logarithmic sine or tangent of the fractional part of a second. The type is clear and the paper good. We can decidedly recommend the work, and have we think shown reasons for our confidence. LXXI. Intelligence and Miscellaneous Articles. On itie Law of Double Refraction. By James MacCullagh, Fellow of Trinity College, and Professor of Mathematics in the University qf Dublin *. IT AV1NG mentioned, in an articlef which I sent a few days -*•-*• ago for insertion in the Philosophical Magazine, that I had been led, in following out an hypothesis, to a law of double refraction more general than that of Fresnel, I think it may be well to state very briefly the nature of that law, and to point out the difference between it and the law of Fresnel, especially as I have since observed that the difference is one of a very extraordinary kind, and one which, if it has a real existence (a question which experiment only can decide), may serve to account for phaenomena that have seemed hitherto inexplicable. I have said, in the article referred to, that when the poten- tial V, which is a function of the second degree, is supposed to contain only the squares and products of the derivatives X, Y, Z, X2, Y2, Z2, X4, &c, we get the law of Fresnel, as well as the law of crystalline dispersion ; but if we make the more general, and apparently the more natural supposition, that it * Communicated by the Author. + On the Dispersion of the Optic Axes, and of the Axes of Elasticity, in Biaxal Crystals. [Inserted in the last Number, p. 293.] 408 Professor MacCullagh on the Law of Double Refraction. contains also the squares and products of the alternate deriva- tives Xj, Y,, Z15 X3, Y3, Z3, &c., then we get, of course, a dif- ferent law. Now I find that there will still be two optic axes for each colour, and that the two directions of vibration in a given wave-plane will have the same relation to them as be- fore ; while the difference of the squares of the two velocities of propagation will continue proportional to the product of the sines of the angles which the wave normal makes with the optic axes; but the sum of the squares of these velocities will be increased or diminished by a quantity proportional to the square of a perpendicular let fall from the centre on the tan- gent plane of a certain very small ellipsoid, this tangent plane being supposed parallel to the wave. Such is the general re- sult for biaxal crystals ; but its bearing will be best perceived by taking the case of a uniaxal crystal, wherein the law of Fresnel reduces itself to that of Huyghens. In this case the wave-surface will, instead of the sphere and spheroid of Huyghens, consist of two ellipsoids touching each other at the extremities of a common diameter, which coin- cides with the axis of the crystal; one ellipsoid differing slightly from a sphere, the other slightly from a spheroid. Neither of the rays will be refracted according to the ordinary law, nor will the wave-surface be symmetrical round the axis. As the law of refraction is unsymmetrical, that of reflexion will be so likewise, and thus we may perhaps obtain an explana- tion of the extraordinary phaenomena observed by Sir David Brewster in reflexion at the common surface of oil of cassia and Iceland spar. It will no doubt appear strange to call in question the ac- curacy of the Huyghenian law, which is generally considered to be established beyond dispute by the experiments of Wol- laston and Malus. But the fact is that no exact experiments have ever been made on the refraction of the ordinary ray. Neither of those philosophers seems to have entertained any suspicion that the ordinary law might be inapplicable to it ; they both took for granted that it followed the law of Snellius. But their results seem to be quite consistent with the suppo- sition that the ordinary index, for rays passing in different directions through Iceland spar, may vary in the third place of decimals, perhaps even in the second. The experiments of Rudberg throw no light upon the question, for it happens, oddly enough, that though he had two prisms in every other case, he used only one of Iceland spar ; he could not there- fore compare the velocities of rays passing in different direc- tions. On comparing his numbers, however, with those of Wollaston and Malus, there is, as Sir David Brewster has Intelligence and Miscellaneous Articles. 409 observed (Phil. Mag., S. 3. vol. i. p. 8), a " surprising discre- pancy," so great indeed as to be quite "alarming." After re- marking the difficulty of finding any explanation of it, Sir David concludes that it must arise from the different refrac- tive powers possessed by different specimens. But though this cause must operate in some degree, we cannot tell to what ex- tent it is effective, and the discrepancy may notwithstanding be occasioned, in a great measure, by a deviation from the Huyghenian law. The whole question must therefore be re- opened, and the ordinary indices for the fixed lines of the spectrum must be determined by means of different prisms cut out of the same piece of Iceland spar. Whatever the result may be, whether it shall confirm the law of Huyghens, or show that another must be substituted for it — it will at least be useful for science, by removing the uncertainty in which the subject is at present involved. Trinity College, Dublin, Sept. 24, 1842. ATOMIC WEIGHTS OF ELEMENTS. MM. Marchand and Erdmarm are at present engaged in a series of researches which seem to prove that Prout's idea that all atomic weights are multiples of that of hydrogen, is correct. They have as yet examined only the following bodies : — Oxygen. . = 100' 1 Hydrogen = 12*5 Carbon . . = 75* 6 Nitrogen =175* 14 Calcium . . = 250 . . . . 20 Chlorine . . = 450 36 Silver .... = 1250 .... 100 Lead = 1300 .... 104 Extract from a letter from Berlin addressed to W. Francis. ON A VERY CURIOUS FACT CONNECTED WITH PHOTOGRAPHY, DISCOVERED BY M. MCSSER OF KCSNIGSBERG, COMMUNICATED BY PROF.BESSEL TO SIR D. BREWSTER*. Sir D. Brewster said, he was requested to communicate an account of some remarkable facts connected with the theory of photography. A new process of producing photographic impressions had been disco- vered by Dr. Moeser of Kcenigsberg ; and an account of the discovery had been brought to this country by Prof. Bessel, who received it from the discoverer himself. The subject was most important, and it would have been a great misfortune if the Physical Section had separated without being made acquainted with it. The following were the general facts connected with it : — A black plate of horn, or agate, is placed below a polished surface of silver, at the distance of one-twen- tieth of an inch, and remains there for ten minutes. The surface of * From the Report of the proceedings of the British Association, Man- chester, June 29, 1 842. — Athenaeum, No. 770. See Dr. Draper's letter on the subject at p. 348 of the present Number. Phil. Mag. S. 3. Vol. 21. No. 139. Nov. 1842. 2 E 4 10 Intelligence and Miscellaneous Articles. the silver receives an impression of the figure, writing, or crest, which may be cut upon the agate, or horn. The figures, &c, do not ap- pear on the silver at the expiration of the ten minutes, hut are ren- dered visible by exposing the silver plate to vapour, either of amber, water, mercury, or any other fluid. He (Sir D. Brewster) had heard Prof. Bessel say, that the vapours of different fluids were analogous to the different coloured rays of the spectrum ; that the different fluids had different effects, corresponding to those of the spectrum ; and that they could, in consequence of such correspondence, produce a red, blue, or violet colour. The image of the camera obscura might be projected on any surface, — glass, silver, or the smooth leather cover of a book, — without any previous preparation ; and the effects would be the same as those produced on a silver plate covered with iodine. This paper gave rise to an animated conversation, in the course of which M. Bessel said that he had seen some of the pictures taken by this process, which were nearly, but not quite, as good as those ob- tained by Mr. Talbot's process. — Sir D. Brewster said, this was the germ of one of the most extraordinary discoveries of modern days ; by it there seemed to be some thermal effect which became fixed in the black substance ; and not only so, but M. Bessel informed him, that different lights seemed to affect different vapours variously, so that there seemed to be something like a power of rendering light latent ; a circumstance which, if it turned out so, would open up very new and curious conceptions of the physical nature of light : on the emission theory, it would be easy to account for this ; on the undulatory theory, he could not conceive how it could be possi- ble.— Prof. MacCullagh said, he believed Newton had somewhere thrown out a suggestion, that luminous particles, as they entered into bodies, might be caught and retained, within certain bounds, by continual attractions. — Sir D. Brewster said, that the experiments which he had performed with nitrous gas seemed to strengthen some such view as this, for, at certain temperatures, we had here an instance of a gaseous body as impervious to light as a piece of iron. — Sir J. Herschel thought it a pity to encumber this new and extensive field of discovery now laid open to them by any specula- tions connected with the theory either of undulations or emissions. He had found that paper could be so prepared, as that the impres- sions of some colours might become permanent upon it, while others were not ; and thus it became possible to impress on it coloured figures by the action of light. He exhibited to the Section a piece of paper so prepared, which, at present, had no form or picture im- pressed on it, but which was so prepared, that, by holding it in a strong light, a red picture would become developed upon it. He wished much he could prevail on Sir W. Hamilton to explain to the Section a metaphysical conception, which he had disclosed to him, and which seemed to him, though darkly he owned, to shadow forth a possible explanation of many difficulties. — Sir W. Hamilton said, that, appealed to by Sir J. Herschel in this manner, he could not avoid placing before the Section the theory alluded to, however im- / Intelligence and Miscellaneous Articles. 411 perfect and obscure. He then explained it ; but we regret our in- ability to express it adequately. It appeared to depend on the con- ception of points, absolutely fixed in space, and endowed with cer- tain properties and powers of transmission, according to determined laws. — Prof. MacCullagh had indulged in speculations allied to, and, as he conceived, involving this very conception of Sir W. Hamilton, and had even followed out some of its consequences, by reducing it to a mathematical form — the conception was of double points, or poles, transmitting powers — but he had abandoned it as mere specu- lation.— Sir D. Brewster thought these speculations tended to re- press experimental research, and to turn men's minds from what was solid to what was fanciful. — Sir J. Herschel considered that there could be no true philosophy without a certain degree of bold- ness in guessing ; and such guessing, or hypothesis, was always ne- cessary in the early stages of philosophy, before a theory has become an established certainty; and these bold guesses, in their proper places, he conceived, should be encouraged, and not repressed. Sir W. Hamilton's conception, he thought, perfectly clear in its meta- physics, and should not be thrown overboard merely because it was mataphysical. ' USE OF IRON WIRE FOR SECONDARY ELECTRO-MAGNETIC COILS. Mr. J. E. Ashby, B.A., of University College, London, informs us that fine iron wire covered with cotton may be substituted for cop- per in secondary coils, with an increase rather than diminution of effect, at less than l-6th of the price, and with a great saving of space. Half a pound of this wire costs Is. 3d. and measures nearly 1400 feet. With secondary coils so constructed, he has been able, he states, to make the magnetic spark pass through nearly l-100th of an inch between two wires, as in Mr. Crosse's experiment ; and by means of a battery of about four square inches negative plate and a length of only 1 100 feet in the secondary, to excite a current in the primary coil. Mr. Gassiot, Mr. Ashby observes, used for the same purpose 2100 feet of copper wire and twenty large cells of Mr. Daniell's battery. NON-CONVERSION OF CALOMEL INTO SUBLIMATE BY THE ALKALINE CHLORIDES. We have in our last Number adduced the numerous experiments of M. Mialhe on the conversion of calomel into corrosive sublimate. The following notice, denying such change, signed Lepage, is from the Journal de Chimie Medicate for September. M. J. Righini d'Ollegio, in a notice relative to the action of the vapour of water on calomel (Jvurnalde Chimie Medicate, Avril 1842), gives the result of an experiment which he performed in order to ascertain if, as had been lately announced, calomel is converted into corrosive sublimate, by the influence of the alkaline chlorides, at the temperature of the human body. M. Lepage states that the result 2 E 2 412 Intelligence and Miscellaneous Articles. announced by the Italian chemist entirely corroborates his own nu- merous observations on the same subject ; and the following he states to be the results of his experiments : — 1. Calomel which is perfectly free from sublimate, digested with its own weight of hydrochlorate of ammonia, or any other alkaline chloride, in distilled water at a temperature of 100° to 104° Fahr., during 24, 36, or even 48 hours, underwent no change of colour. The faltered liquor did not, by means of any reagent, appear to con- tain a trace of a mercurial salt. Some pigeons which were made to drink of this same liquor for several successive days suffered no inconvenience : the calomel lost no sensible weight. 2. The same mixture exposed to a temperature of 122° to 140° Fahr., yielded a liquor which acted precisely in the same way with reagents and on the animal ceconomy as the foregoing. 3. By continued boiling, however, and under the influence of a great excess of chloride, the conversion took place, but only parti- ally.— Journal de Chimie Medicate, Septembre 1842. METHOD OF DISTINGUISHING ZINC FROM MANGANESE IN SO- LUTIONS CONTAINING AMMONIACAL SALTS. BY M. OTTO. If solutions of chloride of zinc and chloride of manganese, con- taining much hydrochlorate of ammonia, be rendered alkaline by so- lution of ammonia, the addition of the smallest quantity of solution of hydrosulphuric acid precipitates white hydrated sulphuret of zinc, whilst no effect is produced by it in the solution of manganese, more being required to obtain a precipitate of the sulphuret of the latter metal. If acetic acid be then added to the solutions, the sul- phuret of manganese dissolves very readily, whilst that of zinc re- mains undissolved. M. Otto advises the use of hydrosulphuric acid and not hydrosulphate of ammonia, because the latter, always con- taining persulphuret, may occasion mistakes, since acetic acid sepa- rates sulphur from it. if, for example, it be required to determine whether iron filings contain brass, they are to be dissolved in aqua regia, the peroxide of iron is to be precipitated by ammonia, the liquor is then to be acidulated, the copper precipitated by hydrosul- phuric acid, and ammonia is then to be added to the filtered liquor, which usually still contains a sufficient quantity of hydrosulphuric acid. If a white precipitate be formed which does not dissolve in acetic acid, it shows that zinc is present. M. Wackenroder has especially recommended the solubility of sulphuret of manganese in acetic acid, to separate manganese from other metals. — Journal de I'harm. et deChem., Sept. 1842. ON MM. VARRENTRAPP AND WILL 8 METHOD OF DETERMINING AZOTE IN ORGANIC ANALYSES. BY M. REIZET. M. Reizet has submitted to examination the new process recom- mended by MM. Varrentrapp and Will, for determining the azote in organic substances. This process is based on the general law of the Intelligence and Miscellaneous Articles. 4-13 decomposition of animal substances, by the hydrated fixed alkalies, into water, carbonic acid and ammonia, if they contain azote. It results from the experiments of M. Reizet, that this process is not entirely free from all chances of error. In the first place the mix- ture of soda and lime retains atmospheric air confined in a peculiar state of condensation ; this air cannot be expelled either by a cur- rent of gas, nor under the influence of a vacuum. During combus- tion, the azote of this air gives rise to ammonia, which is added to that coming from the substance submitted to analysis. Faraday has observed that non-azotized organic substances, even charcoal and the metals which decompose water, yield ammonia when calcined with potash in contact with air. Another chance of error in the process of MM. Varrentrapp and Will results from the circumstance, that the alcohol in which the perchloride of platina is dissolved, reduces this salt to the state of insoluble protochloride ; this operation takes place very slowly, it is true, but it is so considerable that the protochloride formed, mixing with an ammoniacal salt of platina, adds to its weight, and conse- quently sensibly increases the proportion of azote. It is not ex- plained how MM. Varrentrapp and Will always obtained less azote than indicated by theory in the substances which they analysed, since the causes of error in their process tend to give an excess, unless du- ring the operation azote is disengaged either in a free state, or in some other form than of ammonia, or that this gas is not entirely condensed. — Ibid. NEW DOUBLE SALT OF SODA AND PROTOXIDE OF PLATINA. MM. Litton and Schnedermann, endeavouring to discover an easy and certain method of preparing the double cyanides of platina, passed a current of sulphurous acid gas to perfect saturation through a solu- tion of chloride of platina, and afterwards saturated the liquor with car- bonate of soda. They thus obtained a very bulky precipitate, which was nearly colourless, and this, after perfectly washing it, they submit- ted to an attentive examination ; and they found it to be a double salt of soda and protoxide of platina. When dry, this salt is a white powder. It is very slightly soluble in water, and insoluble in alcohol. The usual reagents do not at all indicate the presence of platina in the aqueous solution. If hydrosulphuric acid be passed into it, or if it be mixed with hydrosulphate of ammonia, it does not change even after a long time has elapsed, or by increase of temperature ; but if there be added at the same time an acid which decomposes the salt, the li- quor becomes slowly coloured at common temperatures, and when heated it soon becomes reddish-brown ; and afterwards sulphuret of platina separates. The alkalies, do not decompose this salt; when heated with potash or soda, it undergoes no sensible change. Treated in a dry state with a solution of hydrosulphate of ammonia, or of sulphuret of potassium, it suffers no change at common tem- peratures, but by ebullition it becomes gradually coloured, is even- tually completely dissolved ; and from this solution sulphuret of pla- tina is precipitated by acids. 414 Intelligence and Miscellaneous Articles. 'b Even diluted acids readily dissolve this salt, decomposing it and evolving sulphurous acid. The solution in hydrochloric acid yields crystals of chloride of sodium by evaporation, and by the addition of ammonia a green crystalline precipitate of ammonio-chloride of platina. The solution in sulphuric acid yields, after the requisite evaporation, crystals of sulphate of soda, and assumes the deep colour well known to be owing to the protosulphate of platina. At a cer- tain degree of concentration, metallic platina separates, a property which is well known to belong also to the protosulphate of platina prepared by direct combination. The solution in nitric acid when evaparated by heat has a deep reddish-brown colour ; if to this hydrochlorate of ammonia be added no precipitate is formed, but if the solution be evaporated with the hydrochlorate of ammonia almost to dryness, and water be added to the residue, there remains a great quantity of ammonio-chloride of platina, which does not dissolve. It appears that the reddish-brown colour is owing to the formation of sulphate of platina, a salt, which, as observed by Mr. E. Davy, is not decomposed by hydrochlorate of ammonia, unless they be evaporated together to dryness. The double salt in question dissolves readily in an aqueous solu- tion of cyanide of potassium, and by evaporating the solution, acicu- lar crystals of cyanide of potassium and platina separate. If this salt be exposed to a temperature of 356° to 392° Fahr., it loses its water completely ; ■ and when heated to 464° Fahr. it undergoes no further alteration ; but if the temperature be raised still higher, it begins to suffer slight decomposition, its colour becoming deeper. It requires, however, a continued red heat for its complete decompo- sition, and there then remains a mixture of sulphate and sulphite of/soda with metallic platina. The formula of this anhydrous salt is 3 NaO, S024-Pt O, SO, and that of the hydrated salt 2 (3 Na O, S02+Pt02) + 3H20*.-/W. COMPOSITION OF CONIA. According to M. V. Ortigosa, conia when completely anhydrous consists of 32 equiv. of Hydrogen 199*67 12*55 16 ... Carbon 1213-60 76'31 2 ... Azote 177-04 11-14 Equivalents 159031 100- Pure conia distils without any residue, but if it contains water, a resinous matter is left; its boiling-point is 413° Fahr. Conia is a powerful base ; like ammonia it gives a precipitate with the proto- salts of tin and of mercury, and with the persalts of iron it appears even to expel ammonia from its compounds. It reduces the salts of silver, gives with sulphate of copper a precipitate slightly soluble in water, and very soluble in alcohol and aether. The precipitate obtained by mixing a solution of bichloride of mer- * M. Liebig had previously obtained a double sulphite of ammonia and Krotoxide of platina composed according to the formula 2 S O3, PtO, f2 H6.— Chitnie Organiqtte de Liebig. Paris, 1840, p. 102. Meteorological Observations. 415 cury with conia is insoluble in water, alcohol or sether ; the compound is white, pulverulent, and decomposes at 21 2° Fahr., becoming yellow. If to an aqueous solution of conia one of sulphate of alumina be added, crystals are gradually formed, which with the microscope are easily seen to be octohedrons. These crystals, when they have been carefully washed, blacken if heated on platina foil. — Ibid. mr. luke Howard's cycle of eighteen years in the seasons of britain. The readers of the Philosophical Magazine will doubtless learn with pleasure that the cycle shows well this year to the end of Sep- tember, viz. — 1842. Nine months rain 17'35 inch. 1824. The same 18-68 inch. So that we are 1*33 inch. (only) in arrear for rain. 1842. Average temperature of nine months 50" 86° 1824. The same 49*95 So that we appear to have of heat in advance . . O^l0 The Villa, Ackworth, Sept. 7, 1842. Luke Howard. METEOROLOGICAL OBSERVATIONS FOR SEPTEMBER 1842. Chiswick. — September 1. Constant rain : temperature increasing towards night. 2. Overcast : sultry. 3. Overcast : clear. 4. Cloudy and fine. 5. Foggy : very fine. 6. Very fine : clear. 7. Slight fog : fine. 7 — 10. p.m. violent thunder- storm, much sheet- and sometimes forked lightning : heavy rain, with some hail : clear at night. 8. Boisterous, with heavy rain. 9. Rain : cloudy. 10. Show- ery. 11 — 15. Very fine. 16. Foggy : fine. 17- Cloudy: rain. 18. Fine, with slight haze : rain. 19. Cloudy : showers. 20. Showery. 21. Cloudy and fine : clear. 22. Foggy : cloudy and fine : slight rain. 23. Overcast : heavy rain. 24. Rain : overcast. 25. Slight showers : stormy, with rain at night. 26. Heavy clouds and showers : clear. 27. Overcast : stormy and wet. 28. Fine. 29. Clear : boisterous, with rain. 30. Clear and fine : slight rain. Mean tempera- ture of the month 0*47° above the average. Boston. — Sept. 1. Cloudy : rain early a.m. 2 — 5. Fine. 6. Cloudy. 7. Fine: rain, with thunder and lightning at night. 8. Cloudy. 9. Cloudy: rain early a.m. : rain p.m. 10. Cloudy : rain early a.m. : rain p.m., with thunder and lightning. 11. Cloudy. 12. Cloudy: rain early a.m. 13. Fine. 14—16. Cloudy. 17. Fine: rain p.m. 18, 19. Cloudy: rain early a.m. 20. Fine. 21 Cloudy. 22. Rain. 23. Rain : rain early a.m. : rain p.m. 24. Fine. 25. Cloudy : rain early a.m. 26, 27. Cloudy. 28. Stormy : rain early a.m. 29. Rain and stormy : rain early a.m. 30. Cloudy: rain early a.m. Sandwich Manse, Orkney. — Sept. 1 — 3. Showers. 4. Showers: cloudy. 5. Bright: rain. 6. Rain : clear. 7. Damp: cloudy. 8. Rain. 9. Cloudy: rain. 10. Clear : aurora. 11. Bright : fog. 12. Bright : cloudy. 13. Drizzle : cloudy. 14, 15. Bright: cloudy. 16. Cloudy: drops. 17. Cloudy : clear. 18. Bright: clear. 19. Cloudy: rain. 20. Cloudy. 21. Rain: clear. 22. Rain : drizzle. 23. Damp : dri/zle. . 24. Cloudy. 25. Bright : cloudy. 26. Cloudy: showers. 27. Bright : cloudy. 28,29. Cloudy: clear. 30. Cloudy. Applegarth Manse, Dumfries-shire. — Sept. 1. Very wet morning. 2. Fair but cloudy. 3. Rain p.m. 4. Fine and fair. 5. Thick : rain p.m. 6. Fair but cloudy. 7. Fair and fine. S. Heavy rain early a.m. 14. Cloudy and moist. 15, 16. Fair but cloudy. 17. Rain a.m. 18. Fair and fine : lightning. 19. Fair and fine : thunder. 20. Fair and fine. 21. Fair and fine : thunder. 22. Fair and fine till p.m. : rain. 23. Rain early a.m. 24. Rain. 25 — 28. Fair and cool. 29. Fair and cool : a few drops. 30. 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[THIRD SERIES.] DECEMBER 1842. LXXIL On a Gaseous Voltaic Battery. By W. R. Grove, Esq., M.A., F.R.S., Professor of Experimental Philosophy in the London Institution. To R. Phillips, Esq., F.R.S. My dear Sir, IN the Philosophical Magazine for February 1839 I have given an account of an experiment in which a galvanometer was permanently deflected when connected with two strips of platina covered by tubes containing oxygen and hydrogen. At the conclusion of my notice, I say, " I hope, by repeating this experiment in series, to effect decomposition of water by means of its composition." The next paper of mine published in the same year contains an account of a battery to which the public has since attached my name, and which led me into a different field of research. In reading over my papers lately for a purpose alluded to in my letter of last month, I was struck with the above sentence. My impression was, that I had expressed a hope not very likely to be realized ; but after a few days' consideration I saw my way more clearly, and determined to try the experiment. As the chemical or catalytic action in the experiment de- tailed in that paper, could only be supposed to take place, with ordinary platina foil, at the line or water-mark where the liquid, gas and platina met, the chief difficulty was to ob- tain anything like a notable surface of action. To effect this my first thought was to surround the platina foil with spongy platina precipitated in the usual way by muriate of ammonia. This was suggested to me by the known action of spongy platina on mixed gas, which would by its capillary attraction expose a considerable surface of metal and liquid to the action of the Phil. Mag. S. 3. Vol. 21. No. 140. Dec. 1842. 2 F 418 Professor Grove on a Gaseous Voltaic Battery. gases. I still think this would be the best mode of effecting the object ; but as it was very troublesome in manipulation, I determined to try the platina platinized by voltaic depo- sition from the chloride, as proposed for a different purpose by Mr. Smee. I therefore caused a series of fifty pairs to be constructed, the form and arrangement of which is given in the annexed figure, where ox denotes a tube filled with oxy- gen ; hy one filled with hydrogen, and the dark line in the ow it, axis of the tube platinized platina foil, which in the battery I constructed was about one-fourth of an inch wide. It is ob- vious that, by allowing the platina to touch the liquid, the latter would spread over its surface by capillary action and expose an extended superficies to the gaseous atmosphere. The bat- tery was charged with dilute sulphuric acid, sp. gr. 1*2, and the following effects were produced : — 1st. A shock was given which could be felt by five persons joining hands, and which when taken by a single person was painful. 2nd. The needle of a galvanometer was whirled round and stood at about 60° ; with one person interposed in the circuit it stood at 40°, and was slightly deflected when two were in- terposed. 3rd. A brilliant spark visible in broad daylight was given between charcoal points. 4th. Iodide of potassium, hydrochloric acid, and water acidulated with sulphuric acid were severally decomposed ; the gas from the decomposed water was eliminated in sufficient quantity to be collected and detonated. The gases were evolved in the direction denoted in the figure, i. e. as the chemical theory and experience would indicate, the hydrogen travelling Professor Grove on a Gaseous Voltaic Battery. 419 in one direction throughout the circuit, and the oxygen in the reverse. It was found that 26 pairs were the smallest num- ber which would decompose water, but that four pairs would decompose iodide of potassium. 5th. A gold leaf electroscope was notably affected. 6th. The battery was charged with distilled water; the elec- troscope was affected, and iodide of potassium decomposed. 7th. Although the phenomena were too marked to render it in the least probable that accidental circumstances could have produced the current, still counter experiments were care- fully gone through ; thus the gases were repeatedly changed, oxygen being placed in the tubes which had contained hydro- gen, and vice versa. The effects were equally powerful, and the direction of the current was reversed. 8th. All the tubes were charged with atmospheric air; no effect was produced. 9th. The battery was charged with carbonic acid and nitro- gen in the alternate tubes ; not the slightest effect observable. 10th. It was charged with oxygen and nitrogen; not any effect. 11th. With hydrogen and nitrogen, slight effects. The difference between this and the last experiment at first struck me as extraoi'dinary, but upon consideration was easily ex- plicable. The liquid being exposed to the air would neces- sarily absorb some oxygen, and this with hydrogen would give rise to a current. This was proved by the liquid rising in the hydrogen tubes, but not in those containing nitrogen ; and, as a further proof, one set of tubes was charged with hydro- gen, and the alternate set with acidulated water without gas ; a slight current was perceptible : with oxygen and the liquid in alternate tubes there were no effects produced. 12th. As the oxygen and hydrogen were procured in the first instance by electrolysis, and as Dr. Schcenbein in his careful experiments on polarized electrodes supposed the pe- culiar substance which he has named Ozone to be a principal agent, I caused the tubes to be charged with oxygen evolved from chlorate of potash and oxide of manganese, and hydro- gen from zinc and sulphuric acid ; the effects were the same. The tubes were not all of equal size, nor were they gra- duated ; the exact proportional diminution of gas in each tube could not be ascertained with perfect accuracy ; both gases did diminish, and the hydrogen so much more rapidly than the oxy- gen, that my assistant, who was unacquainted with the rationale of the battery, observed that the hydrogen was absorbed twice as fast as the oxygen. Mr. Gassiot is now preparing a gra- duated battery of this sort, by which the point will be accurately 2F2 420 Professor Grove on a Gaseous Voltaic Battery. determined; supposing the gases at the electrodes and at the plates exposed to uniform facilities of solution, the quantity evolved should be equal to that absorbed. Several curious points are suggested by this novel battery. «. How is its action explicable on the contact theory ? I am by no means wedded to any theory, and have constantly endeavoured to look with the eye of a contact theorist upon the facts of voltaic electricity, but I cannot see them in that light ; if there be any truth in the contact theory, I either misunder- stand it, or my mind is unconsciously biassed. Where is the contact in this experiment, if not everywhere ? Is it at the points of junction of the liquid, gas, and platina? If so it is there that the chemical action takes place ; and as contact is always necessary for chemical action, all chemistry may be referred to contact, or upon the theory of an universal plenum, all natural phaenomena may be referred to it. Contact may be necessary, but how can it stand in the relation of a cause, or of a force? |3. Its phaenomena present to my mind a resolution of cataly- sis into voltaic force, in other words, the action of this battery bears the same relation to the phaenomena of catalysis as that of the ordinary batteries does to those of ordinary chemistry. Whether these effects could be produced by other inoxidable metals (such as gold or silver) is an experiment worth trying. The more we examine chemical and voltaic actions, the more closely do we assimilate them. For some mysterious reason three elements seem necessary for very many if not for all chemical actions. y. This battery is peculiar in having the current generated by gases, and by synthesis of an equal but opposite kind at both anode and cathode; it is therefore, theoretically, more perfect than any other form, as the batteries at present known, act by one affinity at the anode, and have to overcome an- other at the cathode. 8. This battery establishes that gases in combining and ac- quiring a liquid form evolve sufficient force to decompose a similar liquid and cause it to acquire a gaseous form. This is to my mind the most interesting effect of the battery ; it ex- hibits such a beautiful instance of the correlation of natural forces. Many other notions crowd upon my mind, but I have oc- cupied sufficient space and must leave them for the present, hoping that other experimenters will think the subject worth pursuing. I remain, my dear Sir, yours very sincerely, London Institution, Oct. 29, 1842. W. R. Grove. [ 421 ] LXXIII. On the Constant Voltaic Battery. By J. F. Danieia, Esq., For. Sec. U.S., Prof. Chem. in King's College, London ; in a Letter addressed to R. Phillips, Esq., F.R.S., Sj-c. My dear Sir, IT appears from Professor Grove's letter, published in the last Number of the Philosophical Magazine, that I was under a misconception in supposing that he had derived his battery from principles announced by me ; and that my me- mory was treacherous in suggesting that I had heard him, at a very crowded meeting of the members of the London Insti- tution, admit (with a compliment which was impressive, but doubtless much greater than the occasion required) that it was in following up my train of reasoning that he was led to the construction of the instrument whose wonderful powers he was then about to illustrate. But waving this point of re- collection, the error is certainly excusable, inasmuch as the nitric acid battery exactly resembles the constant battery in every particular except the substitution of platinum and ni- tric acid for copper and sulphate of copper ; and an experi- mentalist might, very obviously, have been led to the change by following up the principle of diminishing contrary elec- tromotive powers and resistances to a current originating with the zinc. Professor Grove, however, states (although he " cannot at this distance of time well describe what effect my experiments had upon his mind ") that he cannot acquiesce in the assertion that he was so guided ; but that the idea which immediately led to the construction of his battery is distinctly stated in the Phil. Mag. for 1839. The experiment referred to, with two strips of gold leaf in nitric and hydro- chloric acids, separated by a porous diaphragm, showing that upon contact of the two strips the gold in the hydrochloric acid was dissolved, is certainly a most beautiful one ; but the origin of the force must be admitted to be at the junction of the two acids; which, when a path for its circulation is opened, react upon one another, and transfer by their polarization chlorine to one electrode, and hydrogen to the other; the former being taken up by the gold, and the latter by the nitric acid. What this has to do with the nitric acid battery, in which the two acids in contact are the nitric and sulphuric, I really cannot perceive. The origin of the force in this case has always appeared to me to be the action of the zinc upon the dilute sulphuric acid, but Professor Grove may possibly consider it to be still the contact of the two acids. He has, however, stated that he was so led to the construction of his battery, and X can have nothing more to say upon the subject. 422 The Rev. Professor Kelland's Explanation. It is singular enough that M. E. Becquerel's claim for his father's priority in the discovery of the principles upon which my battery is constructed appears from his reply (also pub- lished in the last Number of the Phil. Mag.) to be founded principally upon a similar supposed generation of force at the contact of the two liquids. If this be its true origin, I at once allow that there is some foundation for the reclamation ; but at the same time I must repeat that such an idea never occurred to me ; as will be evident to those who will take the trouble to consult my con- secutive papers in the Philosophical Transactions: and I must in that case be content with the somewhat mortifying reflection that I was led to a right result by wrong principles. The matter is, however, now fairly before the scientific community, and having corrected M. Becquerel's inadvertent remark about the priority of Professor Grove's experiments, I will promise you to take up no more of your valuable space with the subject. I remain, dear Sir, very truly yours, Kings College, Nov. 2, 1842. J. F. Daniell. To R. Phillips, Esq., fyc. $?c. LXXI V. On certain Arguments adduced in the last Number of the Philosophical Magazine. By the Rev. P. Kelland, M.A., F.R.SS. L. $E., F.C.P.S., ##., Professor of Mathe- matics in the University of Edinburgh, late Fellow and Tutor of Queen's College, Cambridge. To Richard Taylor, Esq. My dear Sir, THE Philosophical Magazine has this moment reached me, by which I am sorry to see that a misprint, or rather a mis-transcription of my paper in the 6th volume of the Cam- bridge Transactions has led both Mr. Earnshaw and Mr. O'Brien astray. I ought to take the blame of this on myself, and do so ; your readers will find my acknowledgement of it at p. 347 of the last Number of your Journal. The three quantities which Mr. Earnshaw copies in p. 341 are not equal. I supposed the axis of y to be that along which transmission takes place, and ought to have made the first and last ex- pression equal to «2, and the middle one to wx2; and so in my own copy it is, but I presume the correction was made with a pen. The equality of these two expressions has been em- ployed by Mr. O'Brien to prove that I do not suppose the axis of y to coincide with the direction of transmission ; and if, in applying the equations I had used these quantities as equal, the argument would have been a strong one. But on The Rev. Professor Challis in Reply to Mr. Stokes. 423 turning to Camb. Trans., vol. vi. p. 180, it will be seen that I have proved them to be unequal. I am truly sorry that this misprint, or mis-transcription, or whatever it may be, has caused so much trouble. It was very natural that it should mislead Mr. Earnshaw, and produce the argument at p. 342 of Nov.' Phil. Mag. ; but I should have hardly imagined it possible to have deceived Mr. O'Brien, who appears to have perceived (see his P.S. p. 34:3) that I supposed the axis ofy to be in the direction of transmission. For having given these gentlemen the trouble of arguing the incorrectness of equations which are undoubtedly erro- neous (if u is not nx in the last line of p. 162), I hope they will accept my apology. I am, dear Sir, with great respect, Your obliged Servant, Edinburgh, Nov. 2, 1842. P. KELLAND. LXXV. On the Analytical Condition of Rectilinear Fluid Mo- tion, in Reply to Mr. Stokes's Remarks. By the Rev. J. Challis, M.A., Plumian Professor of Astronomy in the Uni- versity of Cambridge*. TV/I R. STOKES has brought forward four arguments against -L"J' a new theorem in hydrodynamics which I have advanced, viz. that fluid motion is rectilinear whenever udx + vdy+wdz is an exact differential. The observations I am about to make in reply will follow the order of the arguments. 1. In the first argument (p. 297) it is contended that my de- monstration in the August Number of this Journal is deficient in generality, because it takes no account of the curvature of the lines of motion. I admit the validity of this objection. The geometrical reasoning I have there given proves only that u dx + vdy + iadz is an exact differential when the motion is rectilinear, if the surfaces of displacement are surfaces of equal velocity. I have not proved, as Mr. Stokes asserts, that for the case of rectilinear motion the surfaces of displacement are surfaces of equal velocity. This is not necessarily the case unless udx + vdy + wd she an exact differential. The following demonstration derived from the equation udx + vdy + isodz = V dr, is more to the purpose. In this equation V is the velocity at a point whose coordinates are x, y, z at a given time ; u, v, to are the components of V in the directions of the axes of coordinates ; and d r is the increment of space in the direction of the motion through the point xyss. The proof of the equation is sufficiently well known. * Communicated by the Author. 424- The Rev. Prof. Challis on the Analytical Condition of "Let udx + vdy + wdss be an exact differential. Then, and not otherwise, it is possible to integrate this quantity, and consequently its equivalent V dr, from any one point of the fluid to any other. P and Q (in the figure) being any two points in the fluid, let P R be the line of direction of motion through P at a given time, and let Q R represent the sur- face of displacement through Qat the same time. The integral of u d x + v dy + iv d z, and therefore that of V d r, may be taken indifferently along the line P Q, or along P R and R Q. But the integral of V d r along R Q is nothing, because by hypothesis this line is on a surface of displacement. There- fore the integral of V d r from P to R is identical with the in- tegral from P to Q. Hence if S be the integral, the differ- ential coefficient -7—, which is the velocity at R, is also the dr J ' velocity at Q. This reasoning applies wherever the point Q is situated on the surface of displacement. Hence this surface is a surface of equal velocity. Draw another surface of dis- placement indefinitely near the former. Then if S-f 8 S be the integral of V d r from P to r, the same will be the inte- gral from P to q ; consequently, Q 5 being drawn through Q in the direction of the motion at that point, we have ulti- mately, 8 S = -r~ x the line Q s, and 8 S = -7— x the line Rr. * dr dr Hence Q s, which is ultimately the interval between the sur- faces of displacement at Q, is equal to Rr the interval be- tween them at R. It follows that the surfaces are at all points equidistant, and therefore parallel. A normal to one is there- fore accurately a normal to the other, and the lines of direc- tion of motion are consequently rectilinear. The above reasoning proves that whenever udx + vdy -f w d z is an exact differential the motion is rectilinear. This is the important part of the theorem I have announced, and it is all that there is any occasion to contend for. In my pre- ceding communication I said incorrectly that the exactness of that differential is a necessary condition of rectilinear motion. Nothing that I have advanced disproves the possibility of there being rectilinear motion when udx + vdy + wdz is not an exact differential. 2. If u, vf w be functions of the time, and udx 4- vdy Rectilinear Fluid Motion^ in Reply to Mr. Stokes. 425 + wdz = 0, then by a common step in analytical reasoning, du . dv , dw j _ .j , , , , , d~t ^+ It y + dT } provided dx9 dy, dz do not vary with the time. Hence as it is proved above that dx, dy, dz do not vary with the time in the equation udx + vdy -f tods =0, when the left-hand side is an exact differential (d or dx + dt \ r r ^+ -f1 dz) =°» and these are differential equations of the same curve surface. 3. In answer to the third argument it is sufficient to say, that any proposition proved respecting Jluid motion, that is, motion by which the parts of the fluid alter their relative po- sitions, cannot be affected by motion which is common to all the parts. There is no dependence of the one kind of motion on the other. The equation of continuity and the equation derived from D'Alembert's principle are identically satisfied by the latter kind of motion, which must be considered to be eliminated before any use is made of those equations for de- termining fluid motion. 4. The solution here given of a bydrodynamical problem is inadmissible on this ground. If a direct solution of the problem had been attempted, it would have been found ne- cessary to inquire whether ud w + v dy + wd z were an ex- act differential for that instance ; and no mode of solution could evade the consideration of this question, unless the fluid were supposed to be confined between two cylindrical surfaces indefinitely near each other, and having hyperbolic bases. As in Mr. Stokes's solution that question is. not considered, I conclude that it only applies to the limited case. There is another point connected with this subject, and of no little consequence in the mathematical theory of fluid mo- 426 Dr. Waller's Experiments on the tion, which I am desirous of adverting to. In my former communication I inferred from the writings of Poisson that he did not accede to a proposition which occurs in the Me- canique Analytique, viz. that udx+ vdy + wdz is an exact differential whenever the motion is small. But I am not aware that any general reason has been given for concluding that this proposition is untrue. By putting g for the density of the fluid, and P for h . Nap. log. g, and neglecting powers of u9 v, and w above the first, we have the known equations, dP du dj? dv_ dV^ dw _ ~dlf+ dt ~ ' dy + dt ' dz + dt ~0; the impressed forces for shortness' sake being omitted. Hence approximately, du dv du duo dv dta dy dx9 d z " dx f dz dy ' and it might be argued from these equations that udx+vdy + 1KJ d z is an exact differential for small motions, whether they are rectilinear or not. But the answer is, that the condition of integrability requires that those equations should be identi- cally true, which they cannot be said to be, because powers of u, v,id above the first have been omitted. The same answer applies in another instance. If fluid issues at a constant rate from an orifice in a vessel of indefinitely large dimensions, it may be shown that the conditions of in- tegrability of udx + v dy + isodz are satisfied if the motion at parts infinitely distant from the orifice be neglected. Those equations are, therefore, numerically satisfied ; but as a state of motion differs from a state of rest however large the vessel may be, it follows that they are not identically satisfied, and it cannot therefore be concluded that u d x + v dy + 10 d is is in this instance an exact differential. Cambridge Observatory, Oct. 22, 1842. LXXVI. Experiments on the coloured Films formed by Iodine, Bromine, and Chlorine upon various Metals. By Augustus Waller, M.D.* IN a paper presented by me to the Academy of Sciences of Paris, an extract from which may be seen in the Comptes Rendus for October 5, 1840, I first demonstrated the error committed in ascribing to the iodide of silver alone the power of fixing the vapours of mercury, after it had been exposed * Communicated by the Author. coloured Films formed by Iodine, fyc. upon Metals. 427 to the action of light. Instead of this property being ex- clusively confined to a film of iodide of silver, as obtained in the process of M. Daguerre, I found that it existed in many other substances when presented to the action of light in the state of thin films, viz. by the bromide and chloride of silver ; by the oxide, bromide, iodide and chloride of copper and some others ; all these however possessing less sensibility than the iodide of silver of Daguerre, and therefore less avail- able for the reproduction of the images of the camera than the compound originally discovered by that gentleman. The iodide of Daguerre was found already too little sensitive to the influence of light in this climate, especially when applied to the reproduction of the image of animate objects, so that those films discovered by me seemed still less suitable- to be employed for that purpose ; this objection has, however, been completely removed by recent improvements, more particularly those of M. Claudet, who effected this principally by com- bining the original discovery of Daguerre with those men- tioned above as having been subsequently made by myself. Pursuing the first stage of Daguerre's process, he obtained the film of iodide of silver, and, added to this another film of bromide, either in a simple state, — as practised in my experi- ments published more than six months before, — or after two of these substances had been combined together, as the chloride of iodine and the bromide of iodine, which he was the first to employ. These coloured films, however, merit attention independ- ently of the purposes to which they may be applied in pho- tography : the beauty of some of the phaenomena themselves is peculiarly attractive ; the numerous changes of colour they undergo, either by a variation in the thickness of the film, or by the action of light, assign them a place among the most curious facts of science, and the extreme facility with which they are obtained adds to the interest they excite. Impressed with these ideas, I was induced to pursue a train of investigation on this subject; among the results of which,, one of the most interesting was a new method of making co- loured rings, like those generally known under the name of " Newton's coloured rings," on many of the metals, by the same chemical process as that employed for forming the films of uniform thickness in photography. In order to procure these coloured rings, and at the same time to show the identity of the origin of the colours with those of the ordinary transpa- rent films, that is, as residing simply in the thickness of the lamina and not dependent on the ordinary cause of colour, we have but to place a piece of iodine on a well-polished sur- 428 Dr. Waller's Experiments on the face of silver or copper, and in a short time we find around the iodine a series of coloured zones of the various tints of the spectrum, and approaching in a greater or less degree to the form of a circle, according as they have been more or less disturbed in their formation by currents of the surrounding air. In order that they may be perfectly regular, as large as possible, and with tints undisturbed by the action of light, it is necessary to place a piece of iodine in the centre of a well- polished plate, as before described ; this is then to be shaded by an opake screen superimposed a few lines from the surface to cause the vapours which would otherwise ascend and par- tially escape, to expand over its silver surface. Coloured rings may be formed in the same manner by bromine and chlorine and the various combinations of these bodies with each other, except that for those that are gaseous or liquid it is requisite to pay a little attention to the manner of disen- gaging them on the surface of the metal, either by passing them through a glass tube, or by some other contrivance easy to execute. These rings correspond to those formed by re- flected light in Newton's experiments, with this difference, however, that in the coloured films of the soap bubble, and in those formed by the glass lenses, the thinnest film is in the centre ; whilst in these rings, obtained by chemical action, it exists at the circumference, as is the case with the coloured rings of Nobili. In watching the formation of these pheno- mena, at first are seen two or three very small circles, {which appear almost as soon as the iodine and the metal are placed in contact with each other ; as the experiment continues, the cir- cumferences of these circles become gradually greater ; whilst the external colours extend themselves over a greater space, those of the centre grow fainter ; red and green now only re- main visible, and these at last, when the film has attained a certain thickness, in their turn also give place to a dull coating of brown. The formation of these rings evidently depends on the vaporization of the iodine from the solid nucleus. The variety in colour and extent of these zones is caused by the difference between the strength of the vapour at the centre and the circumference of the iodic atmosphere whilst expand- ing over so large a surface. In the metal thus combining with the vapour, we have to consider, — 1, the force of the vapour at different distances from the centre ; 2, the obstacle which a film of iodine, once formed, opposes to any further action between the iodine and the metal. This experiment may be varied in different ways: two pieces of iodine of about the same size, placed at a small di- stance from each other on a silver plate, form separate co- coloured Films formed by Iodi?ie, fyc. upon Metals. 429 loured circles, until these come in contact at their circum- ferences, when the two systems will slowly coalesce and pro- duce one common outline of the form of an ellipsis. As the colours formed on various metals by the above-men- tioned agents are very similar to one another, it may be suffi- cient to examine in particular those produced on silver by iodine. The external film of the iodide of silver rings, which cor- responds to the central black spot in those of Newton, is com- pletely invisible, it being impossible to perceive any difference between the parts so covered, and those where the metal is intact ; but by exposing half the plate to the influence of light, whilst the other part remains covered, the silver is then found darkened far beyond the limits of the external gold-coloured zone, where previously the surface was perfectly clear. The dark film thus rendered apparent is now liable to be rubbed off by the slightest friction, whereas before it was very adhe- rent to the subjacent surface. The first zone is of a pale gold colour, which assumes a deeper tint as the thickness of the film increases : the second zone is blue, the third white ? after these appear the different colours of the spectrum in re- gular succession, as in the films studied by Newton and others, viz. yellow, orange, red, blue, green, yellow, &c. The pre- sence of the golden-coloured zone in the place mentioned is worthy of remark, as in the tables of Newton of the colours presented by films of various thicknesses, the blue is stated as immediately following the black. The same gold film is the first which appears on most metals when their surface is at- tacked in this manner. Chlorine and bromine on silver ; oxygen on steel ; chlorine and bromine on titanium, bismuth, &c, commence their colours in the same way. Copper, how- ever, is in one respect an exception, this metal first becoming of a dark red, which increases to a ruddy brown and then changes into blue ; this deviation is fully accounted for by the colour of the copper itself; with this single particularity, this metal undergoes the same alterations as the others. The action of light on the different colours of the iodide of silver is very interesting : the most correct way of studying this is to protect one half of a system of coloured rings by an opake screen, while the other half is exposed for a short time to the influence of the solar rays. The golden zone undergoes the greatest change ; at first it grows darker, then red, and at length is converted into a beautiful green. The blue film, which comes next in thickness, suffers considerable alteration in its tint, assuming a much deeper and more brilliant shade ; the rest of the colours appear to be similarly affected by the 430 Dr. Waller's Experiments on the action of light, though to a very slight degree, acquiring a trifling accession in their brilliancy. It has already been re- marked that light destroys the adherence of the external in- visible film: the same thing obtains with the second or gold- coloured film, which turns green, but only to a certain depth of the film, as may be proved by slightly rubbing the part thus altered ; the green colour is then seen to disappear, and beneath the pulverulent portion thus removed is found the gold colour, having almost the same appearance as before the plate had been exposed. As this experiment may be re- peated several times with the same results, it shows to how inconceivably small a depth the light has acted to produce this effect. To ascertain what would take place on augment- ing the thickness of the portion turned green, and the ad- herence of which was destroyed, a piece of iodine was placed on the plate so that its vapour, by expanding, might arrive upon the green, at the same time the whole being kept from the light; the result was that the additional film combined with the one already existing, producing a blue, being the colour which would have resulted by the combination of the unal- tered yellow films. I have found no chemical substance pos- sessing the power of arresting, or in anyway influencing these changes of colour ; strong acids, provided they do not attack the silver, — for then, of course, the experiment would be de- stroyed,— and alkalies in concentrated solution, allow the ac- tion of light to go on as usual. The hyposulphite of soda, and ammonia in solution have no longer the power of dissolving the green film as they had before the action of light. When the plate is left still longer exposed, after the changes above stated have taken place, the colours become more faint, and within the zone of green a white cloudy film is caused by the light, which, as it increases, veils the spectral colours be- neath. The knowledge we at present possess in chemistry of the affinities with which different bodies are endowed for com- bining with each other is but very imperfect, and the causes which complicate most chemical phenomena are so numerous, that it is scarcely possible to compare any two chemical ac- tions to each other. Most of the facts upon which chemical science is founded, are acquired either by bringing the two bodies destined to act on each other into contact by dissolving them in a liquid, or by subjecting them to a temperature more or less elevated. In the first of these methods, we are so far from being able to calculate the force of the chemical powers called into play, that Berthollet was induced to deny the existence of chemical coloured Films formed by Iodine, Sfc. upon Metals, 431 power in the various phaenomena of solution and precipitation of saline substances, and according to him what is called inso- lubility in a body is merely the result of its strength of cohe- sion, an entirely physical property. When the intervention of caloric is required, the effects are still more complicated, as they vary according to the intensity of the heat employed, and the time its action is exerted ; be- sides, the chemical action when it does take place is frequently so instantaneous that it is impossible in our present state of science to imagine any means by which it might be measured. In the combination of the three bodies, iodine, bromine and chlorine, with the metals, however, most of these objections cease to exist, or may be easily avoided. As their vapours com- bine with the metallic surfaces at the ordinary temperature, they are all of them in the same circumstances in that respect ; and if the temperature should be required more elevated, the gasiform state of these substances, iodine not excepted, en- ables us to submit the metals to be experimented upon all at the same time to the same influence. If, therefore, it were possible to reduce the metallic substances into fine powders the particles of which were of the same dimensions, by acting upon them with either of these vapours, an idea might be formed of the affinities which produce their binary com- pounds by the increased weight acquired by the powders in this process ; but the difference which exists in the physical properties of the various metals would preclude the possibility of any near approach to accuracy in this mode of proceeding ; but by acting on the polished metallic surfaces, as in the pre- ceding experiments, all the advantages offered by the process with the powders are included, whilst several of the difficulties are removed. As the film of the compound augments, it un- dergoes the various changes of colour which take place in all transparent films, thus affording a means of ascertaining the absolute thickness obtained in different circumstances, when it would be difficult to detect the slightest difference in weight by means of the most delicate balance. The depth of this coating may be ascertained when either the index of refrac- tion of the compound itself is known, or if the angle of po- larized light is given by means of the law discovered by Sir David Brewster, between the tangent of the angle of polari- zation, and the index of refraction. The most convenient way which occurred to me of performing these experiments, was the employment of a bell-glass within which some iodine is fixed at the top ; this apparatus being placed over the metal to be acted on, the experiment may be watched in all its pro- gress, and the action can be retarded or accelerated at plea- 432 Dr. Waller's Experiments on the sure by varying the interval of the iodine from the metal, or by interposing at some distance from its surface a disc of pa- per so as to cause the vapours of iodine to pass through it. Bromine may be made use of likewise by pouring a few drops of it over some carded cotton, and using it in a similar man- ner with the iodine. In respect to chlorine, it is most con- venient to disengage it slowly by dropping a little sulphuric acid upon some chlorinated lime. In illustration of the objects of this mode of experimenting, I will adduce some of the results it has given me with various metals. Some of the experiments below were performed be- fore I had the idea of watching the progress of the combina- tion through a transparent medium ; they are therefore less exact than they might otherwise have been : but I have pre- ferred stating them as I had inserted them in my note-book befoie I had conceived any idea as to their probable utility in the elucidation of chemical affinity, and when I intended them for other purposes, which I shall hereafter explain. Iodine with Silver and Copper. 1st change, , Silver . . . pale gold. • •• Copper . . . assumes a darker red. • •• Silver . . . blue. 2nd do. Copper . . . blue. ••• Silver . . . white. 3rd do. Copper . . . white. • •• Silver . . . yellow. [silver. 4th do. Copper . . . yellow more extended than on the • •• Silver . . . orange. 5th do. Copper . . . red. ••• Silver . . . blue, bluish-red. [parts. ... Copper . . . red, with a tinge of green on some ... Silver . . . greenish blue. ... Copper . . . red, tinged with green. ... Silver . . . green. ••• Copper . . . orange. ••• Silver . . . yellowish green. ••• Copper . . . orange tending to red. ... Silver . . •. yellowish green. ... Copper . . . orange-red. ••• Silver . . . red. ••• Copper . . . dull green. •«• Silver . . . red. ••• Copper . . . green. •«• Silver . . . deep green. ••• Copper . . . dull red. coloured Films formed by Iodine, fyc. upon Metals. 433 Bromine with Silver and Copper. 5th change. Copper Silver Copper Silver Copper Silver Copper Silver Copper Silver sensibly darkened. unchanged. deep red. unchanged. red, blue. pale gold. white, orange of the 2nd order. yellow. [order. green of the 1st order, red 3rd blue. Chlorine with Silver and Copper. The affinity of chlorine with silver is much inferior to that which it possesses for copper. Iodine with Titanium. Iodine at the common temperature has no action upon this metal. Bromine with Titanium. Bromine, when the surface of this substance is perfectly dry, has no more action upon it than iodine; but if it have a slight coating of moisture, as is formed by merely condensing on it the vapour of the breath, the coloured films are formed without difficulty by the vapours of bromine. Their appear- ance is the same as those of the iodide of silver, viz. gold, deep gold, blue, white, yellow, orange, red, &c. Chlorine with Titanium and Copper. Titanium has a stronger affinity than it has for either of the preceding vapours. The combination takes place when the metallic surface is either dry or moist. Copper . . . much reddened. Titanium . . . not affected. f passed through several of the spectral or- Copper • • •"{ ders °f red and green until it arrived at [_ almost its last changes of colours. Titanium under the same action received a dull film, which viewed obliquely showed red, green, yellow. Silver, exposed to the same influence as the two former, had yellow in the centre and blue more externally. Iodine with Bismuth and Silver. Silver . . . pale gold. Bismuth . . . some parts yellow, others not attacked. Silver . . . blue, white, yellow, orange. Bismuth . . . blue, yellow, orange. Phil. Mag. S. 3. Vol. 21. No. 140. Dec. 1842. 2 G 434 Dr. Waller's Experiments on the In the action of iodine on bismuth, the influence of the physical condition of metallic surface is very manifest. The crystalline texture of this metal may be perceived, and the difference of its hardness admits, to a certain point, of being measured by the difference of the colour of the films that are formed on various points ; while most parts are yellow, there exist others of an angular outline which remain still unat- tacked ; the same difference is remarked in the other stages of the combination. Iodine 'with Mercury. It is impossible to estimate the affinity between mercury and iodine by means of the coloured films, because, on com- bining, these two substances merely cause a dirty white ap- pearance on the surface of the latter. Their combining af- finity appears to be considerable, for when exposed together with silver the action produced with both was red at the edges, little altered in colour; on the rest of its surface a dull white film, in the midst of which were seen several dark spots, where the metal was apparently unaltered. Bromine with Mercury and Copper. J~ Mercury . , . gold colour. 1st. "^Copper t . . slightly darkened. , f Mercury . . . blue. ld,\ Copper . . . dark red. , J Mercury. . . green on some parts. 3rd, ^copper , # t white. After this the copper underwent its usual changes of colour on prolonging the action of the vapour of bromine, but the colour of the mercury suffered no further change. Chlorine with Mercury and Copper. Mercury ... a slight film. Copper ... no alteration of colour. Mercury . . . deep gold colour. Copper . . . deep red on some parts, blue on others. Mercury . . . red tinged with blue. Copper . . . blue, white. Mercury . . . blue. Copper . . . same as before. With respect to the bromide and chloride of mercury, it is necessary to view them obliquely in order to perceive all the changes of colour they undergo; for if looked at perpendicu- larly, there is seen on both a dull uneven film of white which reflects none of the above colours; consequently, to avoid any error, the copper must be inspected under the same angle. coloured Films formed by Iodine, fyc. upon Metals. 435 Bromine "with Bismuth and Silver. Silver . . . pale gold. Bismuth . . . not apparently changed. Silver . . . deep gold, blue. Bismuth . . . yellow, blue. Silver ... blue, yellow. Bismuth . . . dull colourless film. Chlorine "with Bismuth and Silver. Bismuth is slowly attacked by chlorine gas, much in the same way as with iodine and bromine in vapour. Bromine with Lead. At the common temperature neither bromine nor chlorine forms coloured films upon this metal, which it is very difficult besides to bring to any high state of polish on account of its softness. But when lead is heated, as over the flame of a spirit-lamp, the vapours of bromine then form very fine co- loured films, which are in succession gold, deep blue, &c. Iodine with Iron. These two may be made to form coloured films when com- bined rapidly together, but generally a dull coating without any spectral colour is obtained, on account of the deliques- cence of that salt. Until we know the index of refraction of the different films enumerated, it would be impossible to give a correct table of the combining powers in the experiments that have been detailed ; nor is the table of the relative thickness of transparent plates as it has been transmitted to us by Newton, sufficient in the present instance, if any great degree of pre- cision be required. Besides these objections, it is necessary before leaving this subject to pass in review several others inseparable from the mode of performing the experiments themselves. The principal circumstances complicating these experiments and liable to vary in different observations, are, — First, the hardness of the metal acted upon ; 2ndly, the obstacle opposed to the continuation of chemical action by the inert film formed upon the metal ; 3rdly, the force of the va- pours that attack the metal. The influence of the texture of the metallic surface on chemical action is most evident when bismuth is the metal employed. Here the chemical action may be seen to commence on small isolated portions of the surface, which have already assumed a deep gold colour, be- fore other parts are in the least changed, from the natural appearance of the metal. To determine how far this might influence the formation of the iodide of silver, a silver coin 2G2 Pure silver Silver coin Pure silver Silver coin Pure silver Silver coin Pure silver Silver coin Pure silver Silver coin Pure silver 436 Dr. Waller's Experiments on Coloured Films. was exposed to iodine with a piece of pure silver; as the former was so much the harder of the two, it was naturally supposed that the chemical action would be slower in exerting itself on it than on the latter. This, however, was not the case, as may be seen by the following statement of the result of the experiment : — Silver coin . . . pale gold colour, pale gold, deep gold, deep gold, light blue, light blue, yellow. blue, white, yellow not visible, yellow, red at edges, yellow, no red edges, red, blue at edges, yellow, no red apparent. The intensity of the resistance offered by the different films of iodide of silver to a continuation of the chemical combina- tion, may be determined by noting the moment at which the various spectral tints make their appearance. Colour of the film of iodide of silver. . . beginning to darken. . . pale gold. . . deep gold. . . orange blue. . . blue. . . light blue. . . commencement of yellow. . . orange red. . . blue. . . deep blue. . . green. . . yellowish green. . . ruddy brown. . . green. . . green. . . red. . . green. By comparing the thickness of the colours with the space of time required for their production, it will be found, how- ever imperfect the table given by Newton may be when ap- plied to this subject, that towards the end of the experiment above given, the chemical combination is retarded by the pre- sence of the inert film, and that to obtain the same thickness 4 0 50 2 0 4 40 6 40 7 30 9 30 11 30 18 30 20 15 22 55 24 40 28 0 30 25 40 10 46 30 50 10 53 15 Mr. Earnshaw's Reply to Prof. Kelland's Defence. 437 of film as at the commencement, about double the time is re- quired. The third cause of error may be avoided by operating with vapours of about the same force. In those described, the average time employed in passing to the maximum was ge- nerally about half an hour ; if that were not taken into consi- deration, different results might be obtained. In regard to chlorine, there exists another cause of compli- cation, the affinity which it possesses for water ; for when dis- engaged in the ordinary manner, chlorine carries with it a certain quantity of water which may very much alter the re- sults of the experiment. No. 1, St. Mary Abbot's Terrace, Kensington. [To be continued.] LXXVII. Reply to Professor Kelland's Defence of the New- tonian Law of Molecular Action. By S. Earnshaw, M.A. Cambridge *. P ROFESSOR Kelland's defence of the extension of New- ton's law of force to molecular action consists of a critique upon my memoir " On the Nature of Molecular Forces ;" and of a reply to my letter which appeared in your Magazine for July (pres. vol. p. 46). I shall therefore for the sake of precision divide what I have to say in answer to his remarks into two corresponding heads. 1 . With respect to the critique on my memoir, it is evident that it has been written by the Professor under the notion that my investigations have supposed each particle of the medium, except the one for which the forces are calculated, to be in their respective equilibrium positions. I gather this from the repeated charge he brings against me of drawing dynamical inferences from a statical investigation. Will the Professor point out what step, in that part of my paper which is written against Newton's law, requires that the particles of the me- dium should be in their equilibrium positions ? With the ex- ception of the last article, where it is expressly stated that the particles are in equilibrium, my paper is an investigation of the properties of a vibrating medium, i. e. a medium in a state of vibration. At any instant during the motion of the medium I fix upon a particle and investigate the properties of the forces which urge it at that moment ; the other particles meanwhile are supposed to be in the positions which as particles in a state of vibration they had at the instant fixed upon. [Let * Communicated by the Author. 438 Mr. Earnshaw's Reply to Prof. Kelland's Defence the Professor point out one link of my argument against New- ton's law which violates this supposition.] I find as a result that there is always one direction in which the particle is urgedfrom its position of rest ; and therefore, as the motion of the particle in that direction could not be vibratory, New- ton's law cannot be the law of molecular force in the lumini- ferous aether. This explanation, I trust, will enable the Pro- fessor to see that he has written his review of my memoir under the influence of a complete misconception of its nature, to which is due the origin of his complaints that some of my reasonings are unintelligible to him, and that the whole line of my argument is inadmissible (August, p. 130), to which charges it is obviously not necessary for me to make any further reply. There is, however, one argument, which though it belongs to this head, I cannot allow to pass without more particular notice, because upon reading it I could not but consider it as a strong indication of the Professor's having al- lowed other motives than " a desire for truth " (Sept. p. 207) to influence him in bringing it forward. It stands in the Magazine for this month (p. 270) in these words: " I will only add, when it is concluded from the hypothesis of a cubical arrangement of the particles, acting by forces which vary ac- cording to the Newtonian law, that the direction of one side of the cube is stable and of one unstable, ought we not to ask, Is it the hypothesis, or the reasoning based on it which is er- roneous? Must it not of necessity be the latter?" Now one would think from the manner in which this argument is brought forward that the matter animadverted upon by the Professor forms a part of my reasoning. Your readers therefore will be surprised to be informed that it stands in my memoir as a purely casual observation, upon which not a step nor even a word of my reasoning against Newton's law depends. Why then did the Professor bring it forward and draw from it the sweeping inference that my reasoning is erroneous ? Unfortunately for the Professor, in this instance he reaps no advantage by stepping out of the line of legitimate argument, as his objection is founded on the misconception that I have supposed the particles to be in equilibrium. 2. In commencing his reply to my letter printed in your Magazine of July, the Professor calls upon me to state " what I conceive to be the direct effect of matter." I conceive it to be that effect which arises from the supposition that matter and aether act upon each other by attraction or repulsion (en passant, I do not see why I am called upon for this definition, as I have nowhere employed the direct action of matter).' By the indirect action of matter I mean that effect which results of the Newtonian Lata of Molecular Action. 439 when the density and arrangement of the aether are changed by the introduction of particles of matter which exclude some particles of aether from certain portions of space, and thereby affect the equilibrium positions of the remaining particles of aether. The Professor next endeavours to guess the reason why I did not draw from my equations any inferences respect- ing the direct action of matter. The answer is simple ; a most important step required that the vibrating medium should consist of homogeneous particles. The step I allude to is that where (S. 3. vol. xx. May, p. 372) I have " assumed the law of displacement at the time t to be £r = a sin (r h + T)," which assumption is not true when the particles of matter vibrate, be- cause then a could not be invariable through the medium. I think no blame attaches to me for causing this perplexity to the Professor, as I have expressly added, " it will be understood that what follows applies only to media in which this law of disturbance can be transmitted," which I understand to be a formal renunciation of all connexion with the direct action of matter.] The Professor, therefore, in referringme to Mr. O' Brien (October, p. 269) to be set right in my notions, seems to have fallen into the mistake of supposing that what Mr. O'Brien has written on the direct effect of matter (March, note at p. 208) can refute what I have written on the indirect effect of matter. I do not think I fully understand on what ground the Pro- fessor affirms (October, p. 264) that I have not taken account of " the *want of action of particles of aether in the portion of space occupied by the material particles" (October, p. 264); for, as I have taken into account all those particles of aether which do exist, and none else that I am aware of, I sup- pose I must have omitted those which do not exist. Perhaps the Professor will point out what step of my investigation implies the existence of the absent particles. I am next accused (p. 264) of not saying a word about " the pressure of the particles of matter on the adjacent parti- cles of aether tending to stop their motion." In reply it seems sufficient to state, that the particles of matter are supposed to be so few in number in comparison with the particles of aether in a refracting medium, that though a wave may in some de- gree be broken up in its passage through the medium by material impediments, the sensible properties of its general front will remain almost, if not entirely unaffected ; wherefore in an argument based on the broad features of refraction, any allusion to this consideration were a useless refinement, a needless entering upon difficulties, and an unnecessary inter- 440 Mr. Earnshaw's Reply to Prof. Kelland's Defence ruption of my investigations ; which reasons will, I trust, prove satisfactory to the Professor for its having been passed over in silence. The quotation which the Professor gives at the bottom of p. 265 from my letter (April) I can assure him was not in- tended to have any reference to his writings. The Professor must also have mistaken my views when he states (p. 266) that I "appear to look for a complete explanation of disper- sion to the very quarter at which I aim my objections," for I look to the direct action of matter, against which I have not as yet brought forward any objection. In the middle of p. 266 the Professor begins his reply to my remarks on his defence of his numerical calculations. It appears to me that he is hereupon somewhat inconsistent with himself. For (May, p. 378) his words are, " my cal- culations are affected with an error, in that / have neglected to shorten A ; " but here he writes, " the data are not erro- neous." These two statements seem hardly reconcilable. Also, if " the calculations are affected with an error" I do not com- prehend how they can " strengthen theory." What he states (p. 267) about his " formula admitting as many arbitrary con- stants as you please," amounts to a confession that he em- ployed the common principles of interpolations, instead of theory, which is all I have contended for in this part of the subject. The latter part of the Professor's letter is employed in con- troverting my remarks on his proof of the transversality of vibrations. The values of v u' v" which the Professor makes use of in establishing this principle are derived from the equations of motion, which in my last letter I have proved to be non- existent. That letter is therefore a sufficient answer to this part of the Professor's reply. I cannot, however, dismiss the subject without remarking, that the non-existence of normal vibrations is not proved when it has been shown that (u) the velocity of their transmission is imaginary. It must be shown that o is zero, or very much greater or very much less than the velocity of transmission of the transversal vibrations. Por, if it turn out that u is imaginary, the proper inference is, as I have before stated, that the equations of motion have been incorrectly integrated, and the whole investigation needs to be revised. As the remarks which I have made in my last letter respecting the evanescence of the quantity n, and, with it, of the equations of motion extend to all that the Professor has written in his Memoirs on Light, and in his Theory of Pleat, as far as they are respectively dependent on Newton's law of mole- of the Newtonian Law of Molecular Action. 441 cular action, it is needless to enter further upon the inferences from them which the Professor in various parts of his letters has placed in opposition to my results. It now only remains to reply to the accusation (p. 267) that I have fallen into an error in turning the equations of motion into that form, from which I drew all my inferences. I can assure the Professor that I did not lay my investigations be- fore the public, without having first carefully revised them, compared them with what other persons have written on the same subject, and satisfied myself as to the cause of difference where any existed. The Professor may therefore for the future take it for granted that I have seen and examined the equations in M. Cauchy's Memoire sur la Dispersion de la Lumiere, to which he refers me for correction. I fear it will give to my letter an air of great sameness if I again ac- cuse the Professor of misunderstanding what he has under- taken to criticise. I shall not, however, make the charge without bringing forward the proof of it. The Professor tells me that the coefficient of a certain term of my equations dif- fers in appearance from the corresponding coefficient in M. Cauchy's equations ; and his inference is, therefore these co- efficients are not equal, and therefore mine are erroneous. Now I ask, how does the Professor know that these coeffi- cients are not equal ? I admit that they appear to the eye to be different, but the symbol 2) in M. Cauchy's differs entirely from the same symbol in mine. M. Cauchy's coefficients have been brought into the state referred to by reductions sug- gested by theoretical considerations ; but my coefficients were brought into the state in which I leave them by reductions effected upon experimental grounds. j If M. Cauchy's differ in value from mine they disagree with experiment, and are there- fore to be rejected, as will be made manifest by the following process, which applies equally to M. Cauchy's equations and mine own. But I will first state the matter in another way. In my investigations (March, p. 372), A represents the value of 2 {m' <42 F (R)}, the summation represented by 2 ex- tending to all particles in the rth wave surface, and in all other surfaces the particles of which are in the same state of dis- placement as in the rth. Also A represents the value of 2% f Arsin2— -J, 2 now denoting summation for all the values of r in one wave's length. The limiting value of r in performing the operation 2 is therefore the number of par- ticles in a wave's length, which number in any conceivable geometrical arrangement of the particles depends upon the 442 Mr. Earnshaw's Reply to Prof. Kelland's Defence position of the wave's front. Hence Ar and sin2 — de- 2 pend upon the direction of transmission ; but does A, i. e. (t h \ A'r sin2 -— J , also depend upon the direction of transmis- sion ? This question, and a similar one for each of the other coefficients, M. Cauchy has not answered, but I have an- swered it for myself in the negative on experimental grounds, as follows. My equations of motion (and they are M. Cauchy's also) are, %*£= - A£-F)j~E£ dti.m _Ef-D>j-cr. The question is, are the coefficients dependent on the po- sition of the wave's front? Multiply these equations respectively by cos a, cos |3, cos y, and add the results, at the same time 7 9 A . T* COS fi . T-« COS 7 T* T-v COS V assuming ft2 = A + F — + E r- = B + D — % ° cos a cos a cos /3 -r, cos a ~ , -n cos a , ,-. cos Q „ ,.,,.. + F ^ = C + E + D £ ; from which ejrauna- cos p cos y cos y ting cos a, cos /3, cos y, we find the following cubic in Jc\ (£2-A) (F-B) (&*-C)-D2 (&2-A)-E2 (F-B) -F2(F~C) = 2DEF. Having from this found three roots kt% k2% ks% we can then find three corresponding sets of values of cos «, cos /3, cos y ; and our equations of motion by this process of mere algebra take the following simple forms, d?v = --x% #i = - **% i*tv = - vfc where £' = £ cos «j + )j cos /32+ $ cos yj V ss £ cos «2 + >j cos & + $ cosy2 £' = | cos «3 + )j cos /38+ £ cos y3, that is, £' V £' are the displacements of the particle m estimated parallel to a new set of rectangular axes. The forms of the new equations of motion show that these axes are axes of dynamical symmetry, — those in fact which are better known as the axes of elasticity. Now from experiment we know that for waves of a given length k^, &22, k32 are constant quantities, i. e. independent of the position of the waves' front (by the above process I have only changed the axes of coordinates, the waves' front remains unaltered in position). And not to oc- cupy room unnecessarily, I now refer the Professor to the note (July, p. 48) to my letter for the remainder of the proof that " A, B, C, D, E, F are independent of the position of the of the Newtonian Law of Molecular Action. 443 wave's front." By this process it is established beyond the possibility of a doubt, that when the operation represented by £ is performed in the expression which Professor Kelland quotes (p. 268) from M. Cauchy, the result ought to be in- dependent of the position of the wave's front ; and so it is proved either that my equations and M. Cauchy's are identical, or that M. Cauchy's are at variance with experiment. The methods by which we have obtained our equations are perfectly dissimilar, but I believe the equations themselves are identical. In deducing his M. Cauchy has adhered closely to theoretical considerations ; but in deducing mine, I have proceeded to a certain point by the guidance of theory, and then beginning from a more advanced point, where the results of experiment were known, have worked backwards to meet theory. It is therefore easily seen that my results being a mixture of theory and experiment would not present the same appearance to the eye as the results of M. Cauchy, which are obtained from theory alone. They must, however, be identical in fact, or else theory is discordant with experiment. What therefore Professor Kelland has written (p. 268) about " the axis of transmission" is grounded on a misconception, from which also has sprung his idea that " the form of my equations " (p. 46), from which my inferences have been drawn against the Newtonian law, &c, " does depend on the position of the front of the wave." I believe I have now replied to every objection of import- ance which Professor Kelland has brought forward ; I cannot however conclude this letter without remarking, that it is ob- vious that a discussion like the one in which we are now en- gaged never can be brought to a satisfactory conclusion un- less both parties write with perfect candour and a single eye to the discovery of the truth. All arguments which do not really bear upon the Newtonian law must be avoided ; and those which do bear upon it, if after due scrutiny they be found to be true, unhesitatingly admitted with all their consequences. I would therefore, with a view of shortening our labours, re- spectfully request the Professor not to take so wide a field, but to confine himself to the prominent and really important points of the argument ; because if objections of this character cannot be answered, it is clearly quite unnecessary for him to descend with M. Cauchy into the mystical and doubtful sub- tilties of "refined analysis." May I then respectfully re- quest the Professor to answer in the spirit here recommended the four following queries, which seem to me better calculated than any others to bring our discussion to a speedy termina- tion?— 444 Dr. Booth on a Theorem in Analytical Geometry, 1. Does Professor Kelland admit that I have satisfactorily proved that the quantity n used in his memoir on dispersion is equal to zero? 2. Does he admit that the evanescence of that quantity destroys his equations of motion ? 3. Does he admit that the evanescence of his equations of motion destroys his proof of the transversality of vibrations ? 4. Does he admit that the disappearance of his equations of motion in a medium of perfect symmetry whenever Newton's law is introduced, is a sufficient proof that that cannot be the law of molecular action ? If he does admit these points our discussion is at an end ; but if he does not, I shall with great willingness answer any objections against these which he may think it necessary to bring forward. The introduction of collateral questions (such as, " whether the force acts by attraction or repulsion," " whether a cubical arrangement is or is not one of geometric symmetry," " whether the aether has boundaries," " how vi- brations are generated," " whether it is probable that a vio- lent effort would be requisite to move a particle of aether out of its position of equilibrium," and others of a similarly dis- cursive nature which the Professor has mooted in his letters) tends unnecessarily to distract attention from the main ques- tion ; they may therefore safely be allowed by both parties to stand over as unimportant till all objections which are of the first magnitude have been refuted or allowed. Cambridge, Oct. 7, 1842. H LXXVIII. On a Theorem in Analytical Geometry. By the Rev. James Booth, LL.D., M.R.I. A. [Continued from p. 179.] AVING shown that if three fixed points assumed on a ri«*ht line are always retained in three fixed planes, any fourth point P will describe an ellipsoid, whose centre is the common intersection of the three planes, we proceed to establish the following remarkable property, that the volume of this ellipsoid is independent of the angles between the co- ordinate axes ; a singular result, to which an analogous pro- perty may be found in the ellipse. Resuming the equation found at page 1 78, x2 Iv2 z2 2 cos \ 2 cos u. 2 cos v When the equation of the ellipsoid is in this form, having all its terms positive, the point P is supposed to be external to Dr. Booth on a Theorem in Analytical Geometry. 445 the three fixed points ; on the contrary, when P is between any two of the points, the corresponding pair of rectangles become negative. To determine the volume of this surface, let U = 0 , be the equation of a sphere, whose radius is r, referred to the same oblique axes of coordinates, having its centre at the origin, and touching the ellipsoid at one of its vertices; then if a tangent plane to the ellipsoid be drawn at this point, it will also touch the sphere, and we shall consequently have, the equation of the sphere being U z=:x2+y'1+z--\-2yzcos'A-\-2xzcos p+2 xy cos »— r2 = 0 (3.) dV dXJ dV dV dV dV dz " dz9 (4.) dx doc dy dy' as the coefficients of the variables in the equations of the co- incident tangent planes are identical; hence x y z x + y cos v + z cos a ■ -3- + -^tCOSV H COSjU. = - a - a2 ab ac ~ r2 y 2 x ■To + T~ cos A H t- COS V b2 be ab Z CO 7/ -a H cosa + -f- COS A = cz ac ^ be or putting t — — , w = ^-, there results y + z cos A + x cos v . . , - \ ** 9 > ' \5') z 4- x cos ju, + y cos A a t t COSfX. COS |U< __ t + u COS V + COS jU. "I t ~ r a b a c cos A u t cos v b2 ab be u + t cos v 4- cos A 1 tfCOSjX wcosA _ 1 + ICOSfl + mcosA h ~b~c~ + ~bc~~~ (6.) cf o c oc tr From these equations, eliminating t and w, we find the cubic equation, putting 1 — cos2 A — cos4 ft — cos3 v + 2 cos A cos ft cos v = A2, r6 ~r! [Vsin2 X + 42 sin2 fi + c2 sin2 v - (b c cos2 X + a c cosV + a i cos2 i>) + 2(ab + ac-\- b c) cos Xcos /x cos vl -(-L.rjVsin2\ + a2c2sin2u4-a2J2sin2j/ - aftc(acos2X + b cos- p -\- c cos* v) 4- 2 a i c (a + ft + c) cos X cos /t cos v~\ -a36V = 0 . . (7.) 446 Notices of the Labours of Continental Chemists. Now the squares of the three semiaxes of the surface are the three roots of this cubic equation, and as the last term is the product of the roots with the sign changed, we find, calling the semiaxes r1 r" r1", r1 r" r1" = a b c, hence the volume of the ellipsoid = — - r' r" r"1 = — a b c. r 3 3 It is not difficult to show, that the areas of the sections of the surface made by the coordinate planes are it a b, irac, and it be respectively, and in general that the area of any conic section whose equation is A2.r2+ BV + 2ABcosv.#y = 1, is independent of v, the angle between the axes of coordinates, where A and B are the reciprocals of the segments into which the line moving between the axes of coordinates is divided. From this known property that if a line of constant length revolves between two fixed rectangular axes, the locus of the middle point is a circle, may be deduced a method of con- verting rectilinear into circular motion, rigorously exact, and simple in construction, admitting an unlimited length of stroke, and obviating the necessity of using a working beam or connecting rod ; a change which would introduce a de- cided improvement in the construction of the steam-engine*. LXXIX. Notices of the Results of the Labours of Continental Chemists. By Messrs. W. Francis and H. Croft. [Continued from p. 287.] On Hematoxylin. /^HEVREUL examined Campechy wood (wood ofHatma- ^-/ toxylin campechianum, L.) thirty years ago, and found in it a crystallizable colouring principle which he called Haematin, which name has been changed into Haematoxylin to avoid any confusion with the heematin of the blood. Chevreul pro- bably did not procure the body in a state of purity. Erdmann has now examined it, and he proposes the following method for its preparation: — The common extract of logwood is pul- verized and mixed with a considerable quantity of pure sili- ceous sand (to prevent the agglutination of the particles of the extract), and the whole allowed to stand several days with five or six times its volume of aether, the mixture being often shaken ; the clear solution is poured off and distilled until there is only a small syrupy residue. This is mixed with a * [The reader is requested to cotrect some oversights and errors in the preceding part of this paper, it having been printed from an unrevised proof. — Edit.] Erdmann on Hematoxylin. 447 certain quantity of water and allowed to stand for some days, when the hsematoxylin crystallizes out, and may be pressed between bibulous paper, &c. The residual extract itself con- tains more of the substance ; from 2 pounds of extract treated with 10 pounds of aether, Erdmann obtained between 3 and 4 ounces of hematoxylin. The colour of haematoxylin varies from a straw yellow to a deep yellow ; when pulverized it is white or pale yellow. The crystals can be obtained some lines in length ; their form has been studied by Wolff and previously byTeschemacher (Phil. Mag. S. 3. p. 28). It tastes like liquorice root without any trace of bitterness or astringency. Chevreul describes it dif- ferently, but he probably had an impure substance. Haematoxylin dissolves slowly in cold water, but very easily in boiling water. It is necessary to employ water which has been previously boiled, for the smallest possible trace of am- monia causes the haematoxylin to become purple, and Erd- mann proposes this substance as the most delicate test for ammonia : pure oxygen or air freed from ammonia does not alter the colour. The crystals must be dried by pressure in bibulous paper. The filtering paper which is used for the solutions of haematoxylin must be free from lime. Haema- toxylin is soluble in alcohol and aether, but the solution in anhydrous aether does not yield crystals. By exposure to sunlight the substance acquires a reddish colour, but no change in its constitution is effected. It does not sublime, leaves behind a great quantity of char- coal when heated in a tube ; does not evolve ammonia when heated with potassa, and consequently contains no nitrogen. This haematoxylin loses water at ordinary temperatures, and the desiccation is completed at 100-120° C. ; it contains 3 atoms of water, its formula is therefore C40 H34 015+8 H2 O. Another hydrate containing only 3 atoms of water is ob- tained by allowing a hot saturated solution of haematoxylin to cool in a closed vessel, when it separates in small granular crystals. It was impossible to determine the atomic weight of the body. Caustic potassa colours a solution of haematoxylin violet, but by absorption of oxygen the colour passes into purple, brownish yellow, and at last dirty brown. These compounds appear to contain haematoxylin in different degrees of oxida- tion. Ammonia has the same effect, but the presence of air is necessary to effect the change fully ; the ammoniacal solution becomes deep red, almost black. If acetic acid be added to this solution until a precipitate begins to be formed, and it be 448 Notices of the Labours of Continental Chemists. then evaporated, the ammonia being carefully replaced from time to time (excess is to be avoided), a compound crystallizes out in dark violet grains which contains ammonia combined with Htematein ; these crystals must be quickly filtered off and dried by pressure and exposed to the air, but heat must not be employed. The mother liquor may be precipitated by means of acetic acid, haematein falls down in the form of an ochre- red voluminous body like hydrated sesquioxide of iron; when dried it is dark green with a metallic glance, red by transmitted light; the powder is red. Slowly soluble in cold, easier in boiling water. Soluble in alcohol with a reddish brown colour, very little soluble in aether; dissolves in potassa with a blue co- lour, which^exposed to the air passes through red into brown ; with ammonia it gives a purple solution which soon turns into brown; formula C40 H30 O16. Haematoxylin absorbs 3 atoms of oxygen under the influence of ammonia, and forms haema- tein, and 2 atoms of water, C40 H34 O15 + O3 = C40 H30 016+H402. No carbonic acid is formed during the change. Haematein-ammonia is a bluish-black or rather violet-black powder, which under the microscope is seen to consist of quadrilateral prisms. It is soluble in water with an intense purple colour, with alcohol it gives a reddish-brown solution. Heated to 100° C. it loses water and ammonia, it must there- fore be dried over sulphuric acid. When dry it does not decompose of itself, but if moist or in solution a spontaneous decomposition takes place. ' Formula C40 H44 N4 Oi7 ; con- sequently 1 atom of haematein takes up 2 atoms of ammonia and 1 atom of water. Erdmann gives the ammonia com- pound the formula C40 H28 O15 + 2 N2 H8 O, and haematein C40 H28 O15 + H2 O. Haematein-ammonia gives coloured precipitates with most metallic solutions. The lead compound is blue, but it is basic, for the supernatant solution is acid ; at first the washings are colourless, but soon become brown-coloured : it is probable that under the influence of oxide of lead, air and moisture, the haematein undergoes slow oxidation and decomposition. The blue compound was washed a little and then analysed : the organic part of it agreed pretty well with the formula C40 H28 O15. A reddened solution of haematoxylin is decolorated by sulphuretted hydrogen, and on evaporation pure haematoxylin is obtained ; a solution of haematein is also rendered colour- less by sulphuretted hydrogen, but in this no reduction takes place, for on evaporating, as the gas is driven off the solution acquires its original dark colour, and crystals of hae- Opianic Acid — Quinoiline. 449 matein are formed, but not a trace of hsematoxylin. It is evident, therefore, that the sulphuretted hydrogen enters into combination with haematein, as Chevreul has already stated. The lead and copper compounds of haematein were also treated with sulphuretted hydrogen, but in no case was any reduction visible. A few experiments were made on the action of nas- cent hydrogen, which appeared to have better success. — (Journ. fur Prakt. Chemie, vol. xxvi. p. 193.) Opianic Acid. Liebig and Wohler have discovered that this body is pro- duced when narcotine is exposed to oxidizing agencies. It is best prepared in the following manner: — Narcotine is dissolved in a considerable excess of dilute sulphuric acid, finely pow- dered peroxide of manganese is added, and the whole heated : it soon begins to assume a saffron-yellow colour and to evolve carbonic acid. It must be heated to boiling, and this tem- perature maintained as long as carbonic acid is evolved. At the end of the operation there must still be excess of oxide of manganese and sulphuric acid. It is filtered while hot ; the liquid on cooling forms a mass of fine acicular crystals; these must be washed with cold water, and purified by re-solution in water and decoloration with animal charcoal. Opianic acid crystallizes in fine silky needles, whose form cannot be determined. Soluble in hot water but not in cold. Soluble in alcohol. Acts as an acid, but has only a weak bitter sourish taste. Fuses easily into an oil which crystallizes on cooling, but if the temperature has been raised above its fusing point, it remains amorphous. Is not volatile. Heated in the air it gives off the same aromatic odouras narcotine; it inflames easily, and burns with deposition of soot. It expels carbonic acid from its salts, and forms soluble compounds with all bases ; does not contain nitrogen. Lie- big and Wohler are at present engaged in its more accu- rate examination. — (Journ. fur Prakt. Chem. vol. xxvii. p. 97.) Quinoiline. Gerhardt boiled one part of quinine with four parts of po- tassa and one of water in a small retort; the mixture became brown, and a heavy yellow oil passed over with the water. Hydrogen is evolved during the process. If the potassa is not allowed to fuse and the water continually replaced, no ammonia is formed. The oil is evidently alkaline, and forms cry- stallizable salts with acids ; with bichloride of platinum it pro- duces a compound soluble in boiling water, which on cooling crystallizes in golden-yellowneedles. Itsformulais C10'H22 N2 0% Phil. Mag. S. 3. Vol. 21. No. 140. Dec. 1842. 2 H 450 Notices of the Labours of Continental Chemists. H2 CI2 + Pt CI4. Consequently one atom of quinine, by taking up four atoms of water and giving off C4 O4 produces two atoms of quinoiline. This base also forms a crystalline double salt with bichloride of mercury. New liquid bases are also produced by acting with potassa on strychnine, narcotine, &c, but the process is more complex. On Indigo-Nitric Acid (Indigotic Acid). Marchand instituted a series of experiments on this acid with a view to determine its composition, without being aware that Dumas was engaged on the subject: Marchand's results have now been published, and they agree with those already obtained by Dumas. He found the crystallized acid to con- tain three atoms of water, two of which are given off at 150° C, or by long exposure to a dry atmosphere. The third atom is only displaced by bases. The formula of the hydrated acid is C14 H8 N2 O9 + 3 H2 O. The ammonia salt is anhydrous, as is also the silver salt. Neutral indigo-nitrate of baryta was obtained by boiling the acid with carbonate of baryta; it forms shining needles which are difficultly soluble in cold water, insoluble in alcohol and aether. It explodes when heated ; it contains five atoms of water, of which it loses four at 200° C, By boiling with caustic baryta or by the addition of ammonia a basic salt is obtained. It contains two atoms of base and five of water. The potassa salt is anhydrous. The formula of the indigo-nitric acid has a great resemblance to those of the salicyle series. Marchand endeavoured to trace the con- nexion, and in the first place analysed some of the primary compounds, because it was possible that the new atomic weight of carbon might make some difference in their constitution. His analyses of salicine, as well as those of Piria, Mulder, Otto and Erdmann, agree very closely with the formula C28 H38 O15, which explains the decompositions in a very satisfactory manner; the formation of salicylous acid (hydu- ret of salicyle) is very simple, C28 H38 O15 = 2 (C14 H12 O4) + 7 H2 O. Gerhardt has remarked that traces of salicylous acid are formed among the products of the simple distillation of salicine ; this method of preparing it is not, however, advan- tageous, inasmuch as very little is obtained. The best process is that of Piria as modified by Ettling. Three parts bichromate of potassa, three parts salicine, four parts and a half sulphuric acid, and thirty-six water. After twenty parts have passed over, twenty parts of water may be added and again distilled off. Marchand confirmed Piria's formula lor salicylous acid, viz. C14 H12 O4. Salicylic acid may be obtained by fusing salicylite of potassa with excess of potassa, or at once from On the Compounds of Sugar with Bases. 451 salicine, as has been shown by Gerhardt; by fusing salicine with an excess of caustic potassa, hydrogen is evolved ; the mass must not be allowed to become perfectly white, for then some of the salicylic acid is decomposed. Marchand employed two pounds and a half of potassa to half a pound of salicine. If too little potassa is used, resin and salicylous acid are pro- duced. Marchand found the same formula as Piria. If this salicylic acid be mixed with strong nitric acid the action is exceedingly violent, and picrin-nitric acid is produced ; if, how- ever, it be treated with dilute nitric acid the so-called salicylo- nitric acid is formed, which Marchand has shown to be iden- tical with indigo-nitric acid. — {Journ.fur Prakt. Chem.f vol. xxvi. p. 386.) On the Compounds of Sugar with Bases. Berzelius determined the atomic weight of sugar from the analysis of the lead salt, which he considered to be a compound of one atom of sugar with two atoms of oxide of lead. Peligot analysed this salt, and also the compounds with baryta and chloride of sodium, and from them he deduced C24 H36 O18 as the equivalent of anhydrous sugar, which combines with four atoms of base. But the true equivalent is not yet quite settled, for Berzelius threw out doubts as to Peligot's correct- ness ; and the analysis of the baryta salt, upon which the latter chemist places considerable reliance, has been called in ques- tion by Liebig. With a view to clear up these mysteries Soubeiran undertook a series of experiments on tlje subject. As the compounds are very difficult to burn, he employed chromate of lead mixed with bichromate of potassa. Sou- beiran found exactly the same formula for the baryta salt as Peligot; he could not obtain a compound containing less baryta. Brendecke prepared one with only 18*5 per cent, baryta, while the usual one contains 30 per cent. Peligot has examined a combination of sugar with lime ; he considers that it is always formed when lime is brought into contact with sugar ; he found 14 per cent, of lime in it. Daniell however stated that he had obtained a compound containing one third of its weight of lime, by boiling fifteen parts of water with six of lime and ten of sugar for half an hour. Soubeiran could never obtain a compound with so much lime ; the salt he found to be most generally formed is one in which the proportion of the ingredients is as 1:4; this is always pro- duced when the lime is in excess, and the mixture is boiled, or else allowed to stand at ordinary temperatures. Brendecke prepares it by adding half a part of water to a mixture of equal parts of lime and sugar; a resinous mass is formed which 2H2 452 Notices of the Labours of Continental Chemists. is dissolved in water. This salt consists of C24 H44 O22 + 3 Ca O. The compound containing two atoms of lime, 14 per cent., is much more difficult to prepare ; an excess of sugar must be used (sugar thirteen parts, unslaked lime two parts), the salt must be precipitated from its solution by alcohol. Soubeiran could not obtain any other compound of lead but that with four atoms of base. The compounds with potassa and soda have been examined by Brendecke, but are difficult to procure in a pure state, and are moreover deliquescent. Soubeiran did not make any ex- periments on them. From his researches he considers the constitution of an atom of sugar to be C24 H36' O18 = S, and the salts may be arranged as follows : — Crystallized sugar == S-f-4aq. P°comp } = S+R0 Lead comP' = S + 4PbO. ...Probably=S+ {f^O) Lime ... = S+|3 (C.O+EPO) Soda =S+ Na'o Lime ... = S4 {| ^a ° + H2°> ...probably^ S+ { f^'W0) ^'^ % =S+ {|^°+IP0) Chloride of sodium l_o, fNaCl2 compound J ~~ \ 3 aq. (Journ. de Pharm. et deChim. Juin 1842.) Plumbo-Sulphate of Ammonia. Sulphate of lead is considerably soluble in sulphate of am- monia, particularly when boiled. A double salt crystallizes out on cooling ; the best method of obtaining it is to precipi- tate a tolerably concentrated solution of acetate of lead with excess of dilute sulphuric acid ; it is then neutralized with am- monia, and the whole boiled, by which the sulphate is dis- solved. If this does not take place there is a want of sul- phate of ammonia ; if the solution does not deposit crystals on cooling, sulphuric acid must be added until turbidness commences. It appears as if the salt were easier formed when acetate of ammonia is present. The double salt forms small, but bright well-defined crystals. It is decomposed by water, and also by heat, when sulphate of lead and sulphite of am- monia are formed : the latter salt sublimes. It does not con- tain water of crystallization. According to the analysis of Professor Litton, its formula is Pb O, S 03+ N2 H8 O, S O3. — (Ann.der Chem. und Ph., vol. xliii. p. 126.) [ 453 ] LXXX. On a ?iew Imponderable Substance, and on a Class of Chemical B,ays analogous to the Rays of Dark Heat. By John William Draper, M.D., Professor of Chemistry in the University of New York*. [With F igures, Plate I.] IN the Number of this Journal for September 1841, I have pointed out several analogies which may be observed be- tween the phsenomena of the chemical rays and those of ra- diant heat. In this communication it is my intention to show still more striking points of analogy, and also to direct the attention of chemists to equally striking points of discordance. It will be seen from the remarkable facts detailed in this paper, that we are now forced to recognize the existence of a new imponderable agent, analogous in many of its properties to light, heat, and electricity, yet differing as much from them all as they do from one another. So far as chemical analogies can direct us there does not appear any thing unphilosophical in the supposition of the existence of many imponderable agents analogous to those already known. The progress of science has indeed tended in different directions in the cases of the imponderable and ponderable bodies. Among the former, we have successively seen the agents that are concerned in galvanic phenomena and those of magnetism merged into electricity; but the ponderable bodies, especially those of a metallic kind, have greatly increased in number, though so far as their more ob- vious physical properties are concerned, the differences of many are almost undistinguishable. We have thus found it necessary to invert the maxims of the early cultivators of che- mistry, who extended the number of aethereal agents very greatly, and believed that all metals and other ponderable prin- ciples were modifications of one or two primordial and ele- mentary forms. Centuries ago it was discovered that the sun's light had the property of effecting chemical changes in bodies, and it is stated that Scheele first noticed that this property was mainly due to the violet rays. Seebeck observed, that chlo- ride of silver, exposed to the spectrum, varied its colour with the colour of the space in which it was held, and during the present century a very large amount of new observations has been accumulated. A new art, Photography, has come into existence. The general supposition that obtains is, that the effects in question are due to the rays of light ; hence all the words that * Communicated by the Author. 454 Dr. Draper on a new Imponderable Substance, and a have been introduced into use have reference to that supposi- tion ; such words as photography, photology, photometer, are derived from this erroneous hypothesis, and lead us to confound together things which ought to be kept essentially distinct. As it is the object of this paper, and others which I am shortly to publish, to call the attention of chemists to the ao-ent that is involved in photographic results as a clearly established and new imponderable substance, possessing striking ana- logies with light and heat, yet differing as much from them both as they do from each other, I am induced to propose for it a proper name, and to endeavour to establish for it a nomenclature that shall be free from ambiguity and keep the description of its phsenomena separate from those of light. Whilst therefore I show that it undergoes radiation, reflexion, refraction, polarization, absorption, interference, &c. under the laws to which its radiant companions light and heat are sub- ject, I wish to claim for it a separate and independent ex- istence, to introduce it into the natural family of imponderable agents, with light, heat, and electricity. In that family it stands as the fourth member. Is there any reason that the progress of knowledge should not make known to us multiplied forms of imponderable substances as well as of ponderable matters? This agent differs from light and heat, as much as lead differs from zinc or tin. When novel effects, brought about by novel causes, are met with, the purposes of science require new corresponding terms. In the case of the chemical rays of light it is so. I have ex- perienced the need of a nomenclature of the kind from my earliest experiments. It is a rule of which modern philoso- phers know the value, that such names ought to be free from all attending hypothesis ; for if this be not complied with, it soon comes to pass, as knowledge advances, that terms in- volving theoretical ideas lose much of their significance. The chemical rays are associated with the rays of light, accompanying them in all their movements, originating with them, and unless disturbed continuing to exist along with them. But should a compound beam like this fall upon a sensitive surface, the chemical rays sink into it, as it were, and lose all their force, and the rays of light are left alone. Photographic results thus resulting from the reposing of the chemical rays on the sensitive surface are not however in themselves durable, as will be shown in this paper, for the rays escape away under some new form. Tithonus was a beautifulyouth whom Aurora fell in love with and married in heaven. The Fates hadmadehim immortal, Class of Chemical Bays analogous to the Rays of Dark Heat. 455 but unlike his bride, in the course of events he became feeble and decrepit, and losing all his strength was rocked to sleep in a cradle. The goddess, pitying his condition, metamor- phosed him into a grasshopper. The fact and the fable agree pretty well, and indeed the play- ful coincidence might be carried much further. The powers of photography, which bring architectural remains and the forms of statuary so beautifully and impressively before us, might seem to be prefigured by the speaking image of the son of Tithonus and Aurora that was to be seen in the deserts of Egypt. And besides this, such words as Tithonoscope, Ti- thonometer, Tithonography, Tithonic effect, Diatithones- cence, are musical in an English ear. In this paper I shall therefore use the term Tithonicity and its derivatives in the same manner that we use electricity and its derivatives. This communication takes up the consideration of three distinct' facts : — 1st. The proof of the physical independence of Tithoni- city and Light. 2nd. The proof of the physical independence of Tithoni- city and Heat. 3rd. The proof of the existence of dark Tithonic rays, analogous to the rays of dark heat. Under this head it will be shown, that tithonicity like heat enters transiently into bodies producing specific changes on them, and then slowly and invisibly radiates away. And the physical consti- tution of the new class of rays thus formed is entirely differ- ent from that of rays that come from incandescent sources ; a distinction having a striking analogy in the case of heat. Tithonicity becomes transiently and permanently latent in bodies. The Plate (PI. I.), which accompanies this paper, serves to show that by the agency of absorbent media we may detect the existence of tithonic rays in every part of the spectrum unac- companied by light. The results, there projected, were ob- tained by an arrangement such as that in Plate I. 'fig. 1 . From a heliostat mirror a a, a beam of the sun's light was thrown in a horizontal position, and falling on a screen b b, a portion of it passed through a circular aperture one-fourth of an inch in diameter. At the distance of ten or twelve feet it fell on a glass trough c c, with parallel faces, into which any coloured solution could be placed ; immediately behind the trough there was a double convex lens d d, of three feet focal length, and between them a second screen fft with an aperture cor- responding to the centre of the lens, half an inch in diameter. Behind the lens was situated a prism of flint glass e, which 456 Dr. Draper on a new Imponderable Substancet and a effected the dispersion of the incident beam. Now, the lens not being achromatic, the screen /• v had to be placed in an inclined position in order to obtain a neat spectrum-image of the hole in b b, and this was attended with the great advan- tage of elongating the total length of the spectrum, and there- fore increasing the measures. In order to obtain sensitive surfaces of great delicacy the silver plates were first iodized lightly, and then exposed to the vapour of bromine until they attained a full golden yellow. In the Plate, the line No. 1, fig. 3, represents the visible co- lorific spectrum; it, with No. 2, serves as an index of com- parison for all the others. No. 2 represents the effect of a spectrum that has not undergone the action of any absorbent medium on the bromoiodized plate, the extreme red tinges the plate white, the extreme violet brown, and all the inter- mediate space is of a rich brownish violet, with a point of maximum action nearly in its centre. The numerical sub- divisions commence with 0 at the extreme red, and are gra- duated on a principle, which I shall explain in a future paper, which makes the spectra of different tithonographists comparable. No. 3 shows the spectrum after absorption by the persul- phocyanide of iron, and its corresponding tithonograph. This spectrum is divided into three portions, one of which is red and yellow, a second indigo, and a third violet. But the ti- thonograph exhibits an action far beyond the extreme red, half way through the dark space that intervenes in the middle of the spectrum, both ends of this lower part projecting into dark spaces ; whilst the indigo ray, ordinarily so active, does not tithonize at all. Without going into a long descriptive detail of the com- parison of different spectras and their corresponding tithono- graphs, I shall here sum up the results which may be gathered from an inspection of the Plate. By the absorbent action of the persulphocyanide of iron, we can prove the existence of invisible tithonic rays beyond the extreme red, — invisible rays corresponding to the green. We can also prove that the indigo-coloured rays of light may exist without tithonic effect. By the absorbent action of neutral chloride of gold, we can insulate blue coloured rays of light that are not tithonic. The green solution formed by a mixture of bichromate of potash, muriatic acid, and alcohol, enables us to insulate ti- thonic rays of the same refrangibility as the violet, but unac- companied by any light. The solution of sulphate of copper and ammonia enables Class of Chemical Bays analogous to the Hays of Dark Heat. 457 us to insulate a visible red and yellow ray that are without tithonic power, and an invisible tithonic ray beyond the vio- let. The solution of litmus enables us to obtain red and green light without action, and an invisible tithonic ray corre- sponding to the violet. The solution of bichromate of potash enables us to obtain red and orange light without any tithonic effect. Such results might be multiplied without end, for indeed there is scarcely an instance in which spectra of rays that have passed absorbent media are exactly coincident with their corresponding tithonographs. To set the matter plainly be- fore the reader, the following tabular view, gathered from the Plate, may suffice. Name of Solution. Colour of Light without Tithonic effect. Invisible Tithonic rays corresponding in refrangibility to the Persulphoeyanide of iron Extreme red, green. Violet. Extreme violet. Violet. Blue. Sulph. cop. and ammonia Red, orange. Bichromate of potash ... From this, therefore, I infer the entire independence through- out the spectrum of the luminous rays that give to the organs of vision the impression of colour, and the tithonic rays. When I come to describe the dark tithonic rays that are analogous to the rays of dark heat, and which are unaccom- panied by any kind of light whatsoever, no further doubt can be entertained on this subject. I have also some other proofs of a very remarkable kind, to be described hereafter, drawn from the phaenomena exhibited by tithonic rays that have un- dergone polarization. Next, as to the independence of these rays and the rays of heat. One of the most striking proofs of this is the facility with which impressions of the moon's disc may be obtained on Da- guerreotype and other sensitive plates. Even with lenses of comparatively small diameter, and in the space of a few mi- nutes, strong impressions of the moon's surface may be taken. There is no more difficulty in obtaining these sketches than there is in copying a building or a statue, or any other object on which the sun is shining. But the moonbeams have hitherto given no trace of the presence of heat. I found, moreover, by direct trial, that plates which had 458 Dr. Draper on a new Imponderable Substance, and a been carefully prepared so as to be exceedingly sensitive, were unaffected by the radiant heat of copper at any temperature up to a red heat. These dark rays therefore have no kind of effect on such surfaces. A sensitive plate may be made so hot that it cannot be touched, yet its surface remains unchanged, and even the radiant heat emitted by brightly incandescent bodies has no effect, as I also proved. Lastly, — Proof of the existence of dark tithonic rays analogous to the rays o/'dark heat. The experiments, now to be described, were made with Da- guerreotype plates iodized at first to a pale lemon yellow, then brought to a golden hue by immersion in the vapour of bro- mine, and lastly exposed for a short time to the vapour of iodine again. Having exposed such a plate, fig. 2, a b, to the action of weak daylight or lamplight for a period of time which would cause it to whiten powerfully all over if placed in the vapour of mercury, carry it into a room which is totally dark, and suspend at a distance of one-eighth of an inch from its surface a metallic screen c d, the under-surface of which is blackened. Let all remain in the dark four or five hours, and then re- move the sensitive plate a b, and expose it to the vapour of mercury. All that portion of it which was not covered by the screen c d, will undergo no change, but that which was be- neath c d will whiten powerfully. From this remarkable result I infer, that the tithonicity that had originally disturbed the surface of the plate equally all over, has escaped away from those portions that were un- covered ; but that its escape has been entirely prevented by the action of the screen ; and this must be through radia- tion, for the screen is at a distance and has never touched the plate. And, further, that the rays that do thus escape away are absolutely invisible to the eye. Now, suppose a piece of black cloth, placed in the rays of the sun until it has become warm, were carried into a cold room and half its surface screened by some material, as a piece of glass, at a short distance ; there cannot be a doubt that the uncovered portion would cool fast by radiation, but the screen- ed portion more slowly, for its radiation would be arrested by the glass plate. The two cases are absolutely alike. Tithonicity therefore radiates exactly after the manner of heat. This also furnishes proof, in addition to those I have here- tofore given in this Journal, that not only does tithonicity be- come latent in bodies, but that it becomes latent in two Class of Chemical Rays analogous to theRays of Dark Heat. 459 ways, transiently and permanently, exactly after the manner of heat. The same result is obtained when other sensitive surfaces are employed, the period of time differing for different bodies. Guided, therefore, by the analogy of heat, I perceive that bo- dies have a relation to this imponderable agent corresponding to that of specific heat. It follows therefore with certainty that, — The specific tithonicity of bodies is the prime function on which their sensitiveness depends. Under this point of view the sensitiveness is inversely as the specific tithonicity. The circumstances under which this experiment is made serve also to show that metallic bodies are non-conductors of tithonicity. This contrasts remarkably with their action towards heat. Having exposed a sensitive plate a b to light until it would whiten if mercurialized, as before ; and having prepared a se- cond, c d (fig. 2), in total darkness, without allowing any light to have access to it, suspend this latter over the former at the distance of one-eighth of an inch, so as to cover it about half. Keep the two plates in darkness for several hours and then mercurialize both. That portion, a c, of the first, not covered by the second, will not whiten ; that portion of the second, b d, not covered by the first, will also remain unchanged ; but both on those parts that have looked towards each other will whiten. From this I infer, that the portion of the first not over- shadowed by the second does not whiten because its tithoni- city escapes away under the form of dark tithonic rays. I also infer, that as both plates are nearly equally whitened on those portions of their surfaces that have looked towards each other, the dark tithonic rays that have escaped from the first plate, notwithstanding their invisibility, have retained their peculiar chemical force, and have affected the second plate. The analogy with heat is here perfectly observed. A hot non-conducting plate, set partially opposite a cold one, would warm that plate on the portion looking towards it, and through the consequent retardation of radiation would retain its own heat to a certain extent. But all those portions unopposed by the cold plate would cool down by radiation rapidly. This experiment proves in a clear and undoubted manner the total physical independence of tithonicity and light. Hence the absolute necessity of some such nomenclature as that proposed, — the chemical rays of light is a misnomer. On the surface of a sensitive plate that has been suitably exposed, as heretofore, place a fragment of perfectly clean and colourless glass. Allow it to remain there for four or five hours in a dark room, then mercurialize, and it will be found 460 Dr. Draper on a new Imponderable Substance, and a that the portion on which the glass has been placed will whiten powerfully, but all the rest will remain unchanged. This, therefore, proves that colourless glass is nearly opake to the dark tithonic rays, a result observed also in the case of the dark rays of heat. I made a comparative trial of the relative permeability of colourless plate glass and common writing-paper. A sensitive surface was exposed until it had slightly but very plainly com- menced to turn brown. On one portion I now laid a piece of clear glass, and by the side of it a piece of writing-paper ; the arrangement was next placed in the dark for four hours; it was then mercurialized at 160°Fahr. for an hour, and the result was very striking. Notwithstanding the long exposure to the mercury vapour, all those portions that had not been covered were perfectly unaffected, the portion that had been covered by the glass was of an intensely deep brown colour, but the portion covered by the paper was marked by a distinct but very faint white stain. It was therefore plain, that from the uncovered portions all the tithonicity had radiated away, — from the portions covered by the writing-paper the same effect almost to the same extent had occurred, the paper, however, slightly obstructing the passage of the rays, — but radiation had been wholly prevented from those parts covered by the colour- less glass. Writing-paper is therefore far more permeable to the dark tithonic rays than the purest plate glass. This property it will be hereafter convenient to speak of under the designation of Diatithonescence or Transtithones- cence. Blue, red and yellow glass obstruct to a great extent the process of radiation. In several trials it seemed as though the yellow was more transparent than the others, but there was not much difference. Transparent rock-salt appears to hold very nearly the same relation of diatithonicity as plate glass. In like manner the following substances in thin plates ob- struct the radiation of tithonicity : — Sulphate of lime, beryl, agate, rock-crystal, calc-spar, mica, wafers, metallic bodies, cloth of cotton, wood, ivory, coloured glass, &c, &c. The remarkable results described in the Philosophical Transactions by Sir John Herschel (184-0, p. 44), but left by him without any explanation, are of the kind now un- der discussion. He found that paper washed with nitrate of silver, if exposed to the sun under a piece of glass, darkened much more rapidly than if the glass were away. This effect was by no means limited to that variety of paper, but was ob- Class of Chemical Rays analogous to the Rays of Dark Heat. 46 1 servable also with many other tithonographic compounds. Transparent minerals, such as topaz, selenite, Iceland spar, quartz, produced the same results as glass. But on gloomy days the phsenomena did not appear, a bright sunshine being apparently requisite for their production. " When a piece of nitrated paper, for instance, was rolled round a cylindrical surface of moderate convexity, covered with black velvet, and the piece of glass laid gently in contact with it, the effect of sunshine was exalted at the line of contact, but on either side of that line as the interval increased the influence of the glass diminished, and at less than half an inch distance no difference could be perceived between the impressions under the glass and in the free air." Now all this is precisely what should happen if the tithono- graphic compound radiates whilst it is undergoing decompo- sition. The rays, which come from the sun, pass through the glass with but little loss from absorption, falling upon the ni- trate they decompose it, and now it commences radiating, but the physical character of these rays is very different from the character they possessed before impinging on the nitrate. Now they cannot get through the glass, before they passed without difficulty. So it is precisely in the case of heat. Much of the heat of the sun passes through plate glass, and if it falls on a dark surface that can absorb it that surface becomes presently warm and commences radiating; but the physical constitution of these rays is changed, they cannot get through the glass, and if a non-conducting black surface, half covered by a piece of glass and half in the free air, were exposed to the sun, the covered half would for these obvious reasons become the hotter. For the same reason, precisely, in the tithonic experiment the glass increases the final effect by obstructing radiation. It is very obvious why such effects cannot be produced on gloomy days. If at such times we were to expose a piece of black cloth, partially covered by glass, no difference of tem- perature would be perceptible in its covered and uncovered portions. The reasons are analogous in each case. An experiment the same in principle as Sir John HerschePs may be easily made. Upon a sensitive plate, that has been exposed a short time to a feeble light, place a convex lens ; the arrangement being left for a time in a dark room. When you have mercurialized, you will find a central dark point corresponding with the point of contact, and round it a white areola that shades gradually and imperceptibly away. With a lens with which I have occasionally made this experiment, the areola is nearly an inch in diameter, the lens being a double convex of about two inches focus. [ 462 ] LXXXI. On Thermography, or the Art of Copying En- gravings, or any printed Characters from Paper on Metal Plates ; and on the recent Discovery of Moser, relative to the formation of Images in the Dark. By Robert Hunt, Secretary of the lloyal Cornwall Polytechnic Society*. HPHE Journal of the Academy of Sciences of Paris, for the 18th of July, 1842, contains a communication made by M. Regnault from M. Moser of Konigsberg, " Sur la forma- tion des images Daguerriennest;" in which he announces the fact, that " when two bodies are siifficiently near, they impress their images upon each other." The Journal of the 29th of August contains a second communication from M. Moser %, in which the results of his researches are summed up in twenty- six paragraphs. From these I select the following, which alone are to be considered on the present occasion. " 9. All bodies radiate light even in complete darkness. " 10. This light does not appear to be allied to phosphores- cence, for there is no difference perceived whether the bodies have been long in the dark, or whether they have been just exposed to daylight, or even to direct solar light. " 10. Two bodies constantly impress their images on each other, even in complete darkness. " 14. However, for the image to be appreciable, it is neces- sary, because of the divergence of the rays, that the distance of the bodies should not be very considerable. " 15. To render the image visible, the vapour of water, mercury, iodine, &c. may be used. "17. There exists latent light as well as latent heat." The announcement at the last meeting of the British Asso- ciation of these discoveries naturally excited a more than or- dinary degree of interest. A discovery of this kind, changing, as it does, the features, not only of the theories of light adopted by philosophers, but also the commonly received opinions of mankind, was more calculated to awaken attention than any thing which has been brought before the public since the publication of Daguerre's beautiful photographic process. Having instituted a series of experiments, the results of which appear to prove that these phaenomena are not produced by latent light, I am desirous of recording them. I would not be understood as denying the absorption of light by bodies ; of this I think we have abundant proof, and it is a matter well deserving attention. If we pluck a Nastur- * Read at the Cornwall Polytechnic Society, Tuesday, Nov. 8, 1842. f Comptes Rendus, tome xv. No. 3. folio 119. \ Translations of M. Moser's papers containing the full details of his re- searches and discoveries will be published in the course of the present month (December) in Part XI. of Taylor's Scientific Memoirs. Mr. Hunt on Thermography. 463 tium when the sun is shining brightly on the flower, and carry it into a dark room, we shall still be enabled to see it by the light which it emits. The human hand will sometimes exhibit the same phseno- menon, and many other instances might be adduced in proof of the absorption of light; and, I believe, indeed of the prin- ciple that light is latent in bodies. I have only to show that the conclusions of M. Moser have been formed somewhat hastily, being led, no doubt, by the striking similarity which exists between the effects produced on the Daguerreotype plates under the influence of light, and by the juxtaposition of bodies in the dark, to consider them as the work of the same element. 1 . Dr. Draper, in the Philosophical Magazine for Septem- ber 1 840, mentions a fact which has been long known, " That if a piece of very cold clear glass, or what is better, a cold po- lished metallic reflector, has a little object, such as a piece of metal, laid on it, and the surface be breathed over once, the object being then carefully removed, as often as you breathe again on the surface,,a spectral image of it may be seen, and this singular phenomenon may be exhibited for many days after the first trial is made." Several other similar experiments are mentioned, all of them going to show that some mysterious molecular change has taken place on the metallic surface, which occasions it to condense vapours unequally. 2. On repeating this simple experiment, I find that it is ne- cessary, for the production of a good effect, to use dissimilar metals ; for instance, a piece of gold or platina on a plate of copper or of silver will make a very decided image, whereas copper or silver on their respective plates gives but a very faint one, and bodies which are bad conductors of heat, placed on good conductors, make decidedly the strongest impressions when thus treated. 3. I placed upon a well-polished copper plate, a sovereign, a shilling, a large silver medal, and a penny. The plate was gently warmed by passing a spirit lamp along its under sur- face ; when cold, the plate was exposed to the vapour of mer- cury ; each piece had made its impression, but those made by the gold and the large medal were most distinct; not only was the disc marked, but the lettering on each was copied. 4. A bronze medal was supported upon slips of wood, placed on the copper, one-eighth of an inch above the plate. After mercurialization, the space the medal covered was well- marked, and for a considerable distance around the mercury was unequally deposited, giving a shaded border to the image ; the spaces touched by the [mercury?] were thickly covered with the vapour. ' 464 Mr. Hunt on Thermography, 5. The above coins and medals were all placed on the plate, and it was made too hot to be handled, and allowed to cool without their being removed ; impressions were made on the plate in the following order of intensity, — gold, silver, bronze, copper. The mass of the metal was found to influence ma- terially the result ; a large piece of copper making a better image than a small piece of silver. When this plate was ex- posed to vapour, the results were as before (3, 4). On rub- bing off the vapour, it was found that the gold and silver had made permanent impressions on the copper. 6. The above being repeated with a still greater heat, the image of the copper coin was, as well as the others, most faithfully given, but the gold and silver only made permanent impressions. 7. A silvered copper plate was now tried with a moderate warmth (3). Mercurial vapour brought out good images of the gold and copper ; the silver marked, but not well de- fined. 8. Having repeated the above experiments many times with the same results, I was desirous of ascertaining if electricity had any similar effect; powerful discharges were passed through and over the plate and discs, and it was subjected to a long-continued current without any effect. The silver had been cleaned off from the plate (7), it was now warmed with the coins and medals upon it, and submitted to discharges from a very large Leyden jar ; on exposing it to mercurial vapour, the impressions were very prettily brought out, and strange to say, spectral images of those which had been re- ceived on the plate when it was silvered (7) ; thus proving that the influence, whatever it may be, was exerted to some depth in the metal. 9. I placed upon a plate of copper, blue, red and orange- coloured glasses, pieces of crown and flint glass, mica, and a square of tracing paper. These were allowed to remain in contact half an hour. The space occupied by the red glass was well marked, that covered by the orange was less di- stinct, but the blue glass left no impression ; the shapes of the flint and crown glass were well made out, and a remarkably strong impression where the crown glass rested on the tracing paper, but the mica had not made any impression. 10. The last experiment repeated, after the exposure to mercurial vapour ; heat was again applied to dissipate it ; the impression still remained. 11. The experiment repeated, but the vapour of iodine used instead of that of mercury. The impressions of the glasses appeared in the same order as before, but also a very beautiful image of the mica was developed, and the paper well and on the recent discovery of Moser. 465 marked out, showing some relation to exist between the sub- stances used and the vapours applied. 12. Placed the glasses used above (9, &c.) with a piece of well-smoked glass for half an hour, one-twelfth of an inch be- low a polished plate of copper. The vapour of mercury brought out the image of the smoked glass only. .13. All these glasses were placed on the copper and slightly warmed ; red and smoked glasses gave after vaporization, equally distinct images, the orange the next ; the others left but faint marks of their forms ; polishing with Tripoli and putty powder would not remove the images of the smoked and red glasses. 14. An etching, made upon a smoked etching ground on glass, the copper and glass being placed in contact. The image of the glass only could be brought out. 15. A design cut out in paper was pressed close to a cop- per plate by a piece of glass, and then exposed to a gentle heat j the impression was brought out by the vapour of mer- cury in beautiful distinctness. On endeavouring to rub off the vapour, it was found, that all those parts which the paper covered, amalgamated with mercury, which was removed from the rest of the plates ; hence there resulted a perfectly per- manent white picture on a polished copper plate. 16. The coloured glasses before named (9, 12) were placed on a plate of copper with a thick piece of charcoal, a copper coin, the mica and the paper, and exposed to a fervent sun- shine. Mercurial vapour brought up the images in the fol- lowing order: smoked glass, crown glass, red glass, mica beau- tifully delineated, orange glass, paper, charcoal, the coin, blue glass ; thus distinctly proving that the only rays which had any influence on the metal, were the calorific rays. This ex- periment was repeated on different metals, and with various materials, the plate being exposed to steam, mercury and iodine; I invariably found that those bodies which absorbed or permitted the permeation of the most heat gave the best images. The blue and violet rays could not be detected to leave any evidence of action, and as spectra imprinted on pho- tographic papers by light, which had permeated these glasses, gave evidence of the large quantity of the invisible rays which passed them freely, we may also consider those as entirely without the power of effecting any change on compact simple bodies. 17. In a paper which I published in the Philosophical Magazine for October 1840, I mentioned some instances in which I had copied printed pages and engravings on iodized paper, by mere contact and exposure to the influence of the Phil. Mag. S. 3. Vol. 21. No. 140. Dec. 1842. 2 I 4>G6 Mr. Hunt on Thermography, calorific rays, or to artificial heat. I then, speculating on the probability of our being enabled by some such process as the one I then named, to copy pictures and the like, proposed the name of Thermography, to distinguish it from Photography. 18. I now tried the effects of a print in close contact with a well-polished copper plate. When exposed to mercury, I found that the outline was very faithfully copied on the metal. 19. A paper ornament was pressed between two plates of glass, and warmed ; the impression was brought out with tole- rable distinctness on the under and warmest glass, but scarcely traceable on the other. 20. Rose leaves were faithfully copied on a piece of tin plate, exposed to the full influence of sunshine, but a much better impression was obtained by a prolonged exposure in the dark. 21. With a view of ascertaining the distance at which bodies might be copied, I placed upon a plate of polished copper a thick piece of plate glass, over this a square of metal, and se- veral other things, each being larger than the body beneath. These were all covered by a deal box, which was more than half an inch distant from the plate. Things were left in this position for a night. On exposing to the vapour of mercury it was found that each article was copied, the bottom of the deal box more faithfully than any of the others, the grain of the wood being imaged on the plate. 22. Having found by a series of experiments that a black- ened paper made a stronger image than a white one, I very anxiously tried to effect the copying of a printed page or a print. I was partially successful on several metals, but it was not until I used copper plates amalgamated on one surface, and the mercury brought to a very high polish, that I pro- duced any thing of good promise. By carefully preparing the amalgamated surface of the copper I was at length enabled to copy from paper, line-engravings, wood-cuts and litho- graphs, with surprising accuracy. The first specimens pro- duced (which I have the satisfaction of now submitting to your inspection), exhibit a minuteness of detail and sharpness of outline quite equal to the early Daguerreotypes and the photographic copies prepared with chloride of silver*. The following is the process at present adopted by me, which I consider far from perfect, but which affords us very delicate images. A well-polished plate of copper is rubbed over with the ni- trate of mercury, and then well washed to remove any nitrate * The first faithful copy of the lines of a copper-plate engraving was ob- tained by Mr. Cantabrana, who has since succeeded in procuring some to- lerable specimens on unamalgamated copper, which cannot be rubbed off. and on the recent discovery of Moser. 467 of copper which may be formed ; when quite dry a little mer- cury taken up on soft leather or linen is well rubbed over it, and the surface worked to a perfect mirror. The sheet to be copied is placed smoothly over the mercu- rial surface, and a sheet or two of soft, clean paper being placed upon it, it is pressed into equal contact with the metal by a piece of glass, or flat board ; in this state it is allowed to remain for an hour or two. The time may be considerably shortened by applying a very gentle heat for a few minutes to the under surface of the plate. The heat must on no account be so great as to volatilize the mercury. The next process is to place the plate of metal in a closed box, prepared for generating the vapour of mercury. The vapour is to be slow- ly evolved, and in a few seconds the picture will begin to ap- pear ; the vapour of mercury attacks those parts which corre- spond to the white parts of the printed page or engraving, and gives a very faithful, but a somewhat indistinct image. The plate is now removed from the mercurial box, and placed into one containing iodine, to the vapour of which it is exposed for a short time; it will soon be very evident that the iodine va- pour attacks those parts which are free from mercurial vapour, blackening them. Hence there results a perfectly black pic- ture, contrasted with the gray ground formed by the mercu- rial vapour. The picture being formed by the vapours of mercury and iodine, is of course in the same state as a Da- guerreotype picture, and is readily destroyed by rubbing. From the depth to which I find the impression made into the metal, I confidently hope to be enabled to give to these sin- gular and beautiful productions a considerable degree of per- manence, so that they may be used by engravers for working on. It is a curious fact that the vapours of mercury and of io- dine attack the plate differently, and I believe it will be found that vapours have some distinct relation to the chemical or thermo-electrical state of the bodies upon which they are re- ceived. Moser has observed this, and attributes the pheno- mena to the colours of the rays, which he supposes to become latent in the vapour on its passing from the solid into the more subtile form. I do not however think this explanation will agree with the results of experiments. I feel convinced that we have to deal with some thermic influence, and that it will eventually be found that some purely calorific excitement produces a molecular change, or that a thermo-electric action is induced, which effects some change in the polarities of the ultimate atoms of the solid. These are matters which can only be decided by a series of well-conducted experiments, and, although the subject will 2 12 468 Mr. Hopkins on the Elevation and not be laid aside by me, I hope the few curious and certainly important facts which I have brought before you, will elicit the attention of those whose leisure and well-known experi- mental talents qualify them in the highest degree for the in- teresting research into the action of those secret agents which exert so powerful an influence over the laws of the material creation. Although attention was called to the singular man- ner in which vapours disposed themselves on plates of glass and copper, two years since by Dr. Draper, Professor of Che- mistry at New York, and about the same time to the calorific powers of the solar spectrum, by Sir John Herschel*, and to the influence of heat artificially applied, by myself (17), yet it is certainly due to M. Moser of Konigsberg, to acknowledge him to be the first who has forcibly called the attention of the scientific wrorld to an inquiry which promises to be as important in its results as the discovery of the electric pile by Volta. As to the practical utility of this discovery, when we re- flect on the astonishing progress made in the art of photo- graphy since Mr. Fox Talbot published his first process, what may we not expect from thermography, the first rude speci- mens of which exhibit far greater perfection than the early efforts of the sister art ? As a subject of pure scientific interest thermography pro- mises to develope some of those secret influences which ope- rate in the mysterious arrangements of the atomic constituents of matter, to show us the road into the yet hidden recesses of nature's works, and enable us to pierce the mists which at present envelope some of the most striking phaenomena, which the penetration and industry of a few " chosen minds" have brought before our obscured visions. It has placed us at the entrance of a great river flowing into a mighty sea, which mirrors in its glowing waters some of the most brilliant stars which beam through the atmosphere of truth. Falmouth, Nov. 7, 1842. Robert Hunt. LXXXII. On the Elevation and Denudation of the District of the Lakes of Cumberland and Westmoreland. By Wil- liam Hopkins, Esq., F.G.S.-f THE general structure of this district has been long known to geologists through the labours of Professor Sedgwick and other geologists. The object of this paper is to afford theoretical expla- * Philosophical Transactions, Part I. for 1840, page 50. t From the Proceedings of the Geological Society, vol. iii. part ii. p. 757; having been read on June 1st, 1842. Denudation of the Lake District. 469 nations of the observed phenomena of elevation and denudation. The general boundary of tract may be considered as sufficiently defined on the north by the band of mountain limestone which runs from Kirkby Stephen by Heskel, on the west by the coast, and on the south by the discontinuous and irregular band of limestone, which again nearly meets the great mountain limestone ridge of Yorkshire, by whfch, and the great fault along its base, the district is bounded on the east. The general strike of the limestone beds at any point, as well as that of the new red sandstone reposing upon them, coincides with the direction of the boundary at that point, except on the east, where the boundary is the great fault just men- tioned. Consequently the dip is nearly perpendicular to the bound- ary, and round the western side is divergent from the extremity of the axis of the district, which may be considered to extend from near Scaw Fell over Kirkstone and Howgile Fells. On the west the dip frequently amounts to between 20° and 30° ; and it should be remarked, that it appears to be very nearly as great in the new red sandstone beds as in those of the subjacent limestone. The mountain limestone reposes unconformably on the older formations which, within the limestone band, occupy the surface. The gene- ral strike appears to be somewhat north of N.E. and south of S. W. The surface of junction of the mountain limestone and the older formations beneath can be well examined in many places, and the author concludes that the surface on which the limestone was de- posited must have been an even surface in the same sense in which the expression may be now applied, for instance, to the bottom of the German Ocean. He also concludes that this surface must have been horizontal. This will necessarily follow from the previous in- ference, unless it be contended that those animals whose remains are now found in the lower limestone beds could exist in the per- fect performance of all the functions of life, at the depth of several thousands of feet, under an enormous pressure and in darkness, as well as at small depths, under small pressure and in the light of the sun. This surface of junction wraps round the outer portion of the district, and, if continued as an imaginary surface, over the central portion in the manner which the inclination of the existing portion would obviously suggest, it would pass considerably over the tops of the highest mountains of the district, to which it would form a complete envelope. Hence it follows that if the movement which produced the geological elevation of the existing portion of the sur- face of junction affected the central portion of the district in the same manner as in all analogous cases in which the evidence is complete, it will follow that the present surface of the Cumbrian mountains must have been beneath the surface of the ocean at the commencement of the deposition of the mountain limestone. The truth of this conclusion involves that also of the original horizon- tality of the surface of junction. The stratification of the older rocks of the district can afford no 470 Mr. Hopkins on the Elevation and direct evidence on this point on account of the previous disturbance to which they had been subjected ; but the great faults of the di- strict prove to demonstration that its central portion must have been submerged in the ocean subsequently to the formation of those faults ; for, if an enormous denudation had not taken place after their formation, every large fault must have given rise to a mural precipice, or great ridge (such as that which the Penrin and Craven faults have produced), by the elevation of the mass on one side of the fault relatively to that on the other. The total absence of any such precipice or ridge where enormous faults unquestionably exist, prove incontrovertibly the submergence above asserted. Faults. — The faults of this district may be arranged in three classes, according to the evidence we possess of their existence : — (1.) Those which offer conclusive evidence of dislocation. Such are those of the Dudden, Coniston Water, one between Coniston Water and Windermere, Trentbeck and Kentmere. (2.) Faults along the Lake valleys. The existence of these faults is inferred from that of the Jakes, the formation of which it would appear impossible to account for without referring them to disloca- tions along the valleys in which they are found. The bottom of Wastwater, for instance, is probably at a considerably lower level than the surface of the sea, and it has not been formed by the filling up of the lower end of the valley, for the bottom of it con- sists of the solid rock in situ. It appears inconceivable that such a lake should have been scooped out by the action of water. (3.) Faults along the upper portions of other valleys. If the Lake valleys have originated in dislocations we seem justified in inferring, from analogy, that other valleys differing from the former only in the circumstance of not containing lakes, have had a similar origin. It should be remarked, however, that this evidence can probably be depended upon only in the upper parts of the valleys, where denuding agencies must probably have acted for a much shorter period than at lower levels, where they may have formed valleys much more independently of previous dislocation. Theory of Elevation. — If we allow the conclusiveness of the above evidence of faults, we have here a system of which the law is obvious. Round the western extremity of the district they diverge from its highest point and extremity of its axis of elevation. On the north side they assume northerly, and then north-easterly, di- rections ; and on the southern side they take southerly directions. If we conceive a stratum of the mountain limestone, or the surface of junction above described to be continued over the central portion of the district, its dip along the faults would very nearly coincide with their directions. This is one of the laws connecting the directions of dip and of dis- location, resulting from the theory which the author has elsewhere developed, supposing the faults to have been caused by the elevation which gave to the limestone beds their present position. This theory would therefore appear to assign these faults to the epoch of the Denudation of the Lake District. 471 disturbance of the carboniferous system. There is also, however, another law pointed out by that theory, viz. that a system of dislo- cations may also exist having the same directions as the strike of the disturbed beds. Consequently those faults which are in the direction of the strike of the beds of the older formations, may, according to this theory, be assigned to the epoch of the elevation and dislocation of those beds. The great faults of the Dudden, Coniston Water, and Troutbeck are of this class, since their direc- tions coincide very nearly with the mean strike of the older beds. Theory, therefore, leaves the epoch of these faults undetermined ; nor has the point been settled by observation, since there is no direct evidence to prove whether these faults have affected the mountain limestone or not. It may be thought that the mountain limestone must have been more decidedly disturbed by the great faults above mentioned had they been produced at the epoch of the disturbance of the carboni- ferous system. It must be remarked, however, that the direct evi- dence of these faults is found only at a considerable distance from the existing portions of mountain limestone, and that if they originated in that central and local elevation to which the actual configuration of this tract must be due (at whatever epoch it took place), the diver- ging faults, however great near the centre of the district, would dis- appear as they approached its boundary. The author, however, is disposed to refer the four great faults above mentioned to the disturbance of the older rocks. They appear to have produced such enormous, relative displacements of the masses on opposite sides of them, as may be more probably referrible to the more in- tense action of the elevatory forces which disturbed the older formations than to that which subsequently took up the mountain limestone. But, it may be urged, the directions of these great dislocations do not coincide with that of the actual strike of the older beds. The author shows that if this coincidence existed (as it ought according to theory) after the elevation of the older beds, but previously to that of the limestone, it could not possibly exist after the latter ele- vation in those parts in which the deviation from such coincidence is now recognised, viz. along the band of limestone interstratified with the older beds, and crossing the above faults in its course from the Dudden to Troutbeck. To one who has a distinct con- ception of the geometry of the subject, it will easily appear that the elevation which gave its present position to the beds of mountain limestone, and (as the-author conceives) its dome-like configuration to the district, would necessarily give to the strike of the beds along the above line, a direction approximating more to east and west than the original strike, while it would have no effect on the direction of a vertical fault as determined by its intersection with the surface. This accounts for the actual difference between the directions of the above faults and that of the strike. Upon the whole, the author considers it probable that the four 472 Mr. Hopkins on the Elevation and great parallel faults above mentioned are due to the elevation of the older rocks, the fractures having been probably renewed by the elevation of the carboniferous series. The divergent faults he con- ceives to be unquestionably due to the movement which impressed upon the district its peculiar configuration, and the geological ele- vation to which that configuration is due, whatever be the epoch to which that movement may be referred. If this be the case, these faults are entirely in accordance with theory. It appears to the author that this movement commenced with the breaking up of the carboniferous series, and was continued, or rather perhaps resumed, after the deposition of the new red sand- stone. If the beds of these formations were originally horizontal, as above contended, this conclusion must necessarily be true, as shown by the present inclination of these beds. Whether the lime- stone beds were strictly sedimentary, or formed in the manner of coral reefs, the author contends equally for the original horizon- tality of the surfaces of stratification ; and that such was the ori- ginal character of the beds of new red sandstone, no geologist, he conceives, can doubt for a moment. If this be allowed, the above conclusion respecting the epoch of elevation appears as incontro- vertible as the nature of geological evidence will admit of. Series of Geological Events. — After the elevation of the older rocks, including the old red sandstone, the whole district must have been under the surface of the sea, and subjected to the powerful action of denuding causes, by which the upturned edges of the disturbed beds were worn to an even surface, and the existing masses of old red conglomerate washed into the hollows. The mountain limestone was deposited on the worn and even surface of the older rocks, and, if the conditions were sufficiently favourable for its formation, may have extended over the whole district. The great movement which broke up the carboniferous series gave, in part, its dome-like form to the district, and elevated its sur- face very nearly to, or perhaps above, the surface of the ocean. The deposition of the new red sandstone afterwards took place, but did not probably extend over the district on account of the ele- vation already given to it. This formation probably thinned off as it approached the central elevation, but was deposited in much greater thickness than it has at present in the Vale of Eden. From the present height and thickness of the sandstone near Penrith, the author thinks it probable that the depth of the submarine valley immediately west of Stainmoor was not more than 300 or 400 feet, and perhaps considerably less, measuring from the level of the lowest part of the Stainmoor pass. To this period of repose succeeded another of disturbance, in which the new red sand was dislocated and elevated. It was during this period, the author conceives, that the surface of the district first began to acquire any permanent and considerable elevation above the surface of the sea. The denudation of the red sand Denudation of the Lake District. 473 would commence with these movements, but was probably com- pleted only as the whole tract of country emerged slowly from be- neath the surface of the sea. If we reject the glacial theory in its application to the transport of blocks, as totally inadmissible in the case before us, this emergence must necessarily have taken place subsequently to the transport of blocks from the Cumbrian moun- tains across Stainmoor. The author conceives the valleys of the district to have been formed during this gradual emergence ; the action of denuding causes being facilitated by previous dislocations, the masses, the removal of which formed the valleys, would at the same time be transported and spread over the surrounding country. The forma- tion of the existing lakes must have been one of the most recent events in the geological history of this region. Period of Transport of Erratic Blocks.— The author thinks that geologists have frequently limited too much the period during which the transport of blocks may have taken place. When blocks are found reposing on an undisturbed formation, the only con- clusive inference which can be drawn from the fact is, that the last stage of their movement was posterior to the deposition of the beds on which they rest. If the beds be much disturbed, but all the irregularities and asperities of its external surfaces worn away by long-continued attrition, we may generally conclude that the same action would have worn away any blocks previously existing on its surface, and therefore any blocks now existing on such surface must have been lodged there subsequently to its denudation. Also, when diluvial gravel contains organic remains, we may conclude that the last stage of its movement must have been subsequent to the existence of the animals whose remains are entombed in it. To contend, for instance, that the diluvial gravel of Norfolk was not re- moved from its original site till the post-tertiary period, is to draw an inference which the author deems altogether inadmissible. The great mass of diluvium from the Cumbrian mountains re- poses on nothing more recent than the new red sandstone, and the author conceives that its transport might begin with the elevatory movements which disturbed that formation, when the surface of the present mountainous district began to rise permanently above the surface of the ocean, and the valleys began to be formed. This is the more remote limit of the period to which the transport of diluvium and blocks can be referred ; the other limit is the emer- gence of Stainmoor (over which so many blocks passed) from be- neath the surface of the ocean, assuming the total inadequacy of the glacial theory to account for that transport. The present height of Stainmoor is stated to be about 1500 feet above the sea; consequently an elevation of from 1500 to 2000 feet must have taken place in these regions since the transport of the Cumbrian blocks across the Penim ridge — a fact which appears corroborative of the author's opinion, that the district had scarcely emerged from the ocean at the more remote of the above-mentioned limits of the possible period of transport. 474 Mr. Hopkins on the Elevation and Modes of Transport — Glacial Theory. — This theory, in its appli- cation to the transport of blocks across Stainmoor, involves such obvious mechanical absurdities, that the author considers it totally unworthy of the attention of the Society. Polished and striated rocks were, however, detected by Dr. Buckland, and pointed out by him to the author in various places. The author does not feel himself called upon to offer any decided opinion as to the cause of such phaenomena ; he here speaks of the glacial theory only with re- ference to the solution it offers of the problem of the transport of blocks or detritus to distant localities. Iceberg Theory. — There appears to be no doubt that floating ice may have played an important part in some cases in the transport of large blocks, but the author doubts whether such agency has been at all employed in the case under consideration. In the first place, he cannot but consider it absurd to attribute the formation of a bed of diluvium spread out with approximate uniformity over an extended area to the action of floating ice. Such a distribution of the trans- ported matter is the necessary effect of broad currents of water, which, at most, is the merely -possible effect of floating ice. Se- condly, there appears no adequate reason why blocks transported by floating ice should diminish in size as their distance from their original site increases ; why the Cumbrian blocks on the eastern coast of Yorkshire should be generally much smaller than those less remote from the place whence they came. Thirdly, the theory in its application to the case before us involves a great physical diffi- culty— a depression of temperature, for which no adequate cause has yet been assigned. The author does not admit the parallel which has been drawn between this case and that of places in equal latitudes in South America or that of the island of Georgia. Transport by Currents of Water. — It has already been remarked that the spreading x>ut of diluvial matter into a horizontal stratum may be regarded as the necessary consequence of broad general currents, and that this has been the agency by which the mass of diluvium covering the surface of Lancashire has been carried there does not admit, in the author's opinion, of the smallest doubt. He accounts for the existence of currents diverging from the centre of the district in question by a repetition of paroxysmal elevations. Suppose a certain area at the bottom of an ocean to be suddenly elevated ; and, for the greater clearness, suppose the elevated area to be a circle of twenty miles in diameter, its elevation to be 50 feet, and the depth of the ocean 300 or 400 feet. If the elevation were sufficiently gradual no sensible wave would result from it, but if it were sudden the surface of the water above the uplifted area would be elevated very nearly as much as the area itself, and a diverging wave would be the consequence. Its front would be steep, like that of the tidal wave in some rivers called the bore, so that the highest part or summit of the wave would not be far from its front. The height at its summit would be approximately equal to the ele- vation of the uplifted area, or, in the case supposed, nearly 50 feet. The velocity with which the front would diverge would depend on Denudation of the Lake District. 475 the height of the wave and the depth of the ocean. In a certain time the water first raised above the general level of the ocean imme- diately over the elevated area would run off, leaving the surface of the ocean there at its original level ; and when this should be com- pleted the posterior boundary of kthe wave would be immediately over the periphery of the elevated area. During the same time the front of the wave would move on through a certain space, still form- ing a circle of which the centre would be immediately over that of the elevated area. Thus the whole wave would at the instant now referred to be comprised between two concentric circles, the distance between which would be the breadth of the wave. After- wards, as the front or anterior boundary of the wave spread out- wards, so would the posterior boundary move forward in a similar manner, always preserving the annular form just mentioned. As the wave diverged its height would gradually diminish till it be- came finally insensible. The motion of the wave here spoken of is altogether distinct from the motion of translation of the aqueous particles. This latter motion, however, accompanies the former in the kind of wave here described, producing a current like that of a tidal river oppo- site to the usual course of the stream. Each particle begins to move onward the instant when the anterior boundary of the wave has reached it, but its motion being always slower than that of the wave, it will afterwards be overtaken by the posterior boundary of the wave, which will then leave the fluid particle behind and at rest. Thus, at any proposed point, the current will begin when the front of the wave reaches that point, will increase there till the highest part of the wave is directly over it, and will then gradually decrease till the posterior boundary of the wave has reached the point in question, where the current will then cease altogether. There will be no reflexion of this great solitary wave unless it meet with some obstruction in the course of its motion. We are indebted to Mr. Russel for our knowledge of the pro- perties of these great waves of translation. He has further ascer- tained, experimentally, that the velocity of the wave is equal to that which would be acquired in vacuum by a stone falling under the action of gravity through a height equal to half the depth of the ocean measured from the crest of the wave. He has also found that the velocity of the current at any point is independent of the depth of that point, being the same at the bottom as at the surface*. From these data it is easy to calculate the velocity of the current which attends the wave, when the depth of the ocean and original height of the wave are known. And hence it appears that there is no difficulty in accounting for a current of twenty-five or thirty * Mr. Russel's experiments were made with much smaller waves and at much smaller depths than those above spoken of ; but he expresses a con- viction (and, as the author conceives, a well-founded conviction) that the same results will hold for much greater depths than those experimented with. 476 Mr. Hopkins on the Lake District. miles an hour, if we allow of paroxysmal elevations* of from 100 to 200 feet. This velocity will decrease as the wave expands, unless the current be constrained to pass through a comparatively narrow channel, like that which must have been formed by the pass Stainmoor when just submerged beneath the surface of the ocean. In such case the velocity of the current might be much increased. With respect to the magnitude of the blocks which might be moved by a current of given velocity, the author remarks, that the facility with which the transport of a block may be effected depends principally on its form. The more it approximates to per- fect sphericity, the less, cceteris paribus, will be the force necessary to remove it. The author conceives that there is no doubt what- ever but that blocks, not more spherical than many rolled blocks are observed to be, of five tons weight and upwards, might be moved under favourable circumstances, by a current of ten miles an hour. That the force of a current increases in the ratio of the square of its velocity has been distinctly established by experiment for all velocities up to eleven or twelve miles an hour ; nor does there appear to be any reason for doubting that the same law holds for much greater velocities. Assuming this law, the author states it as the result of a simple calculation, that if a certain current be just able to move a block of given weight and form, another cur- rent of double the velocity of the former would move a block of a similar form, whose weight should be that of the former in the ratio of 26 : 1, i.e. of 64 to 1. If the velocity of the second cur- rent were treble that of the first, the weights of the two similar blocks would be in the ratio 36 : 1, i. e. of 729 to 1, and so on for other velocities. Hence, if a current of ten miles an hour would move a block of five tons, a current of twenty miles an hour might, under similar circumstances, move one of 320 tons. No transported blocks approximating to this weight appear to have been moved from the Cumbrian mountains. The author, therefore, does not hesitate to affirm the entire adequacy of the cause now explained to transport all the erratic blocks which have been identified as be- inf derived from that region, nor can he therefore hesitate to con- clude that such has been the agency by which that transport has actually been effected. It has been urged that no current could carry boulders up the escarpment of the Eastern Wolds of Yorkshire, nor does the author contend for any such effect of currents. Whether the blocks now found on the wolds were transported there by currents or by float- ing ice, the transport must have taken place before that region emerged from the ocean. But the author contends that the forma- tion of such an escarpment as that referred to, or like the oolitic * If the extent of country elevated be considerable (like that of the district of the Lakes, for instance) the elevation might occupy several minutes and still produce the great wave above described. If the elevation were produced more slowly, the height of the wave, and consequently the velocity of the current, would be proportionably less. Proceedings of Learned Societies. 477 escarpment which overlooks the valley of the Severn, could not possibly be formed by oceanic currents, except under very peculiar conditions, which we have no reason to believe to have existed in those localities. On the contrary, the formation of such escarp- ments during the gradual emergence of the land would be a neces- sary consequence of that emergence under conditions which must have obtained in numerous instances. Hence the author concludes that the escarpment of the wolds was formed subsequently to the transport of the blocks which are now found in that region. He conceives that, with respect to the theory of transport by currents, difficulties founded on existing inequalities of surface have been far too strongly contended for on the one hand, and too easily admitted on the other. The author is anxious that his views should not be misunder- stood as respects the glacial theory, or that which would refer the transport of blocks to floating ice. He is quite prepared to believe in the possible extension of glaciers beyond the boundaries to which they now extend, wherever such greater extension can be ac- counted for consistently with the conclusions of collateral branches of physical science ; and also to believe that such more extensive glaciers, where they have existed, may have been the means of transport of erratic blocks, provided sufficient mechanical cause can be assigned for their movement. With respect to the iceberg theory, though he rejects its application to the case investigated in this communication as altogether unnecessary to account for the observed phaenomena, he conceives that floating ice may probably have been the most efficient agent in transporting the larger blocks of colder regions from their original localities. LXXXIII. Proceedings of Learned Societies. ROYAL ASTRONOMICAL SOCIETY. [Continued from p. 401.] March 1 1 , f ■ THE following communications were read : — 1842. JL 1. On an Instrument adapted for observing Right Ascensions and Declinations of Stars independently of time, accom- panied by Drawings made with the Camera Lucida by Captain Basil Hall, R.N. By M. Wettinger. Communicated, with a Letter of De- scription, to Sir J. F. W. Herschel, Bart., by Capt. Basil Hall, R.N. The instrument contrived by M. Wettinger is so fully described in Captain Hall's letter, that an independent abstract of M. Wettin- ger's paper is unnecessary. The- following is a copy of the letter, dated Malta, Dec. 6, 1841 :— " My dear Sir John, — I have had my attention lately called to an invention which appears to me so ingenious, and grounded upon such good principles, that I think a description of it may interest you, and perhaps be considered by you as worthy of being brought to the notice of the Astronomical Society. Of this, however, you 478 Royal Astronomical Society, are the best judge ; and I shall therefore merely give you the means of examining the pretensions of the instrument. In this view I have made three sketches of the model with the camera lucida, and I have added to each the same letters of reference to the same parts. I transmit to you also the opinion of Carlini of Milan, and of his col- leagues, as to this instrument, which was submitted to their ex- amination some time ago. " I may begin by stating that the chief object of the instrument is to determine the difference of right ascension between any two stars, without the agency of time as an element, the equatoreal an- gular difference between them being measured directly, in arc, on an hour-circle, graduated in degrees and minutes for that purpose. It is true that time does enter as an element into the principle of the instrument, inasmuch as a certain part of the machinery is moved by clock-work, in the manner used in many equatoreals ; but this agency is purely mechanical and subsidiary, and does not require that the absolute time should either be exactly known, or its march be exactly kept. " The instrument is essentially an equatoreal arc, in its structure, — that is to say, its principal axis is directed to the pole, and it carries a telescope capable of being directed to any star which is above the horizon. [I should mention, in passing, that the clock-work ma- chinery is not included in the model ; and there may be observed some other mechanical omissions, it not having been thought worth while to encumber either the model or the description with more details than are necessary to an explanation of the principle and workings of the instrument.] " The principal or polar axis of the instrument is made hollow — in fact, is a telescope, having at its upper extremity a small reflector or speculum capable of being directed at any angle into the tube of this axis telescope. The object-glass of this telescope is fixed not at its extremity, but about half-way between the upper end and the centre. At the centre there is placed another reflector, which stands at an angle of 45° with the length of the tube, to receive the image of a star formed by the object-glass from the rays reflected from the upper speculum. The side of the axis telescope is perforated, in order to allow the image of the star which is reflected from the central speculum to pass into the middle of another telescope, which, for di- stinction, may be called the declination telescope, as it is attached to, and carries with it, a declination circle. In the middle of this de- clination telescope there is fitted a very small reflector, at an angle of 45° to its length, on which the image of the star reflected from the central speculum is received and transmitted to the eye of the observer, in every position of the declination telescope. " The further arrangements of the instrument will perhaps be more readily understood by describing the manner of using it, than by giving a detailed explanation of the parts. " In commencing an observation, the upper speculum is directed to a standard star of the first or second magnitude, partly by moving it on its own axis of rotation, so as to direct the rays into the prin- Royal Astronomical Society. 479 cipal axis telescope, and partly by the equate-real motion, either of the whole apparatus, or by the rotatory movement of the principal axis, by means of the declination telescope. This motion, I may mention by the way, of the principal or polar axis may be made at pleasure, independently of a large frame- work attached to the in- strument, which is moved by the clock-work, There is an hour- circle in the plane of the meridian, fixed to this outer frame- work, and another circle fixed to the lower extremity of the polar axis, which may be clarfijped or freed from that which belongs to the frame- work. The speculum, at the other extremity of the axis, is so con- trived that it moves along with the frame-work. " It will therefore be understood, that if the upper speculum be so directed towards a star that the rays reflected from it pass down the polar axis telescope, they will be received and reflected, first, from the central speculum, and secondly, from the speculum in the declination telescope, to the eye, in whatever position the declina- tion telescope may be. Now, if the hour-circles be clamped, so as to form one, and the frame-work be put into gear with the clock- work, the whole will move round at the rate observed by the heavens, and, consequently, the image of the star reflected from the upper speculum will continue in the centre of the field of the declination telescope, for any required length of time, and in every possible po- sition of that telescope. " Suppose, now, that the relative position of the equatoreal circle, fixed to the frame, and that carried by the polar axis, be carefully ascertained by reading off their graduated circumferences, by micro- scopes or otherwise, and that then the circle carried by the polar axis be undamped, that axis will be left free to revolve and to carry with it the declination circle, and Likewise the declination telescope, but without interfering with what may be called the celestial move- ment of the frame, or that of the upper speculum, which, by going along with, continues to reflect the rays from the star to which it was originally directed ; and, consequently, to preserve the image of that star constantly in the centre of the field of the declination tele- scope. This declination telescope is now directed to any other given star whatsoever, the image of which, viewed directly, is to be brought into coincidence with that seen by reflection from the upper specu- lum. If now the equatoreal circles be clamped, and a second set of readings be made, it is obvious that the difference between the two will be the difference, in arc, of the right ascensions of the stars. " When the observation commences, the declination telescope is directed to the standard star, as well as the upper speculum, so that the images, seen direct and by reflection, are made to coincide in the centre of the field of view of the declination telescope. The graduations of the declination circle are then read off, to be com- pared with those when the second observation is made, or that of the star whose place is to be determined. The difference of these readings will give the difference of the declinations of the two stars, in the same manner that the difference of the readings of the two 480 Royal Astronomical Society. concentric hour-circles (as they may be called) at the lower end of the polar axis, gives the difference of the right ascensions. " If clock-work machinery be not in such perfect adjustment as to keep the standard star, first observed, correctly in the centre of the field of view, it may be brought to that point by a tangential movement of the frame-work, to be made by hand, at the moment of making the second observation, without in any respect vitiating the integrity of the observation, for this small movement does no more than compensate for any error in the goingpof the clock. " As it may not be always convenient to move the whole frame which is attached to the clock-work, the upper speculum, at the upper end of the axis, is so fitted as to be capable of being turned round independently of the frame, to which it is fixed by a mode- rately stiff collar. This movement, which may be made roughly by hand, or more nicely by a tangent screw, enables the observer, without stopping the clock-work machinery, to direct the speculum to any given standard star ; and I may observe that only those of the first and second magnitudes are named for this purpose by M. Wettinger, as he fears the light lost by the three successive reflec- tions might. render any less brilliant stars invisible. This, however, does not affect stars viewed through the declination telescope, which looks directly to its object, and is supposed to be capable of seeing small stars as readily as large ones. " Observations for determining the differences of right ascension and declination, in arc, between a standard star and any other, both being above the horizon, may be repeated as often as required ; and it does not appear how, supposing the machinery perfect, any error can enter into these determinations, except what arises from the false position in which refraction places celestial objects. In the determination of right ascensions by an instrument placed in the meridian, this source of error is avoided ; but it remains in full force as to declinations. The question with respect to right ascensions, therefore, resolves itself chiefly (if I rightly understand M. Wettinger) into the fact of its being both easier and more exact to determine the difference of right ascension in arc, by a leisurely and direct ob- servation of the angle formed by the two meridians in which the stars lie, than to infer that difference of arc by the uncertain agencv of a clock, which is further vitiated, he thinks, by the uncertainty of marking the exact moments when the stars respectively pass the wires of the meridian instrument. To these sources of error he adds that of the ear in appreciating the beats of the clock. " M. Wettinger is of opinion, that, although only experience can determine the degree of accuracy with which such an instrument could give the desired results, very fair estimates may be formed by practical astronomers familiar with the difficulties and errors of the existing methods, of the probable advantages of his invention. Whether, for example, the effects of refraction on stars above a cer- tain altitude, on their right ascensions and declinations, are not suf- ficiently well known to admit of such exact corrections being applied to the determinations made by his instrument, as would render their Royal Astronomical Society. 481 results more worthy of confidence than those made with the existing instruments. It being taken into account, also, that, while only one observation can be made in the day on all stars which are not circum- polar, and only two on some of those which never set, with an in- strument fixed in the meridian, the number of observations which may be made with M. Wettinger's instrument is unlimited ; and as these observations might be made at all altitudes from that when the stars passed the meridian to the moment of their rising or setting, many curious inferences might possibly be deduced from it on the subject of refraction, while the observations might be so arranged as to counteract the vitiating effects of refraction, and, by the com- bination, to give correct results. " It would seem that this instrument would be very useful in de- termining the place of a comet by direct observation, instead of in- ferring it, as is usual, even with an equatoreal instrument. For this purpose any standard or other star sufficiently brilliant to bear the triple reflection may be used. " It will be observed in Signor Carlini's report, that, a doubt having been expressed as to the possibility of applying the principle of this instrument to the sun, M. Wettinger, in order to try the ex- periment, fixed the small reflector or speculum of his model to the great equatoreal at Milan, in. such a way that, while Sirius was ob- served directly by the telescope, the image of the sun, duly darkened and submitted to one reflexion, was observed in the same apparent direction ; and both, as he informs me, with such perfect precision, that the star could be seen on the disc of the sun, or be brought in contact with the limb with the utmost certainty. " It will be observed that Signor Carlini and his colleagues, in their report, advert to the multiplicity of parts and variety of move- ments in M. Wettinger's instrument, as contrasted with the fixed nature and simple operations of the large meridian instruments now in use. But still they appear to be disposed to look with a favourable eye to the capabilities of M. Wettinger's invention, and they seem anxious that one of sufficient dimensions should be made ; but for this, in their opinion, there are no means in Italy, and they recommend Munich or Vienna. Why not London ? " M. Wettinger is of opinion that prisms of glass might probably be substituted with advantage in place of the reflectors. " As I may probably have omitted some material points in this explanation, I have requested M. Wettinger to draw up a descrip- tion of it in Italian, the only language which he speaks ; and I have asked him to employ the same letters of reference which I have used, so that the same sketches may do for both. " I ought to add, that M. Wettinger is one of the professors of the university established here, and that he has long been highly esteemed for his knowledge and ability, and he is a person well ac- quainted both with the principles and the practice of astronomy. " Should you wish it, or should you think it would prove inter- esting to the Astronomical Society, to see the model which M. Wet- tinger has constructed, I have no doubt he would readily allow it to Phil. Mag. S. 3. Vol. 21. No. 140. Dec. 1842. 2 K 482 Royal Astronomical Society. be sent to England ; or should you wish any further information respecting it, you will do him a favour by writing to him at Malta. I shall not be here above a month longer, as I go on to Egypt with my family in January ; but M. Wettinger being fixed to this spot, will always be available. — I remain, &c. " Basil Hall." II. A Letter from Professor Henderson to the Secretary, dated Edinburgh, January 31, 1842, on the Determination of the Parallax of a Centauri, by recent Observations made by Mr. Maclear at the Cape of Good Hope*. " My dear Sir, — Within these few days I have received from Mr. Maclear a series of observations of a1 and a2 Centauri, made with a view to ascertain the parallax ; and I find that they confirm the existence of a parallax amounting to about one second. The observations are of the double altitudes of the stars made with the mural circles, and they extend from April 16, 1839, to August 12, 1840. Twenty-six observations of the double altitude of each star were made with the old circle between April 16 and June 16, 1839; and 108 observations of the double altitude of a1, and 112 of a9, were made with the new circle between August 4, 1839, and August 12, 1840. In each observation the star was observed both by direct vision and by reflexion at the same transit. The results which I have obtained are as follow : — " From the 272 observations made with both circles, Parallax = 6-91. Weight 147*93 observations. Coefficient of Aberration = 20-55. ... 142*47 ... " From the 220 observations made with the new circle, Parallax = 6*92. Weight 138-81 observations. Coefficient of Aberration = 20-53. ... 12797 " The observations made with the old circle extend over too short a period to warrant any results beng deduced from them alone for parallax and aberration which could be relied upon. " On computing the observations of each star separately, I find for a1, — " From the 134 observations made with both circles, Parallax = 0-86. Weight 70*37 observations. Coefficient of Aberration =20-61. ... 70*02 " From the 108 observations made with the new circle, Parallax = 0*91. Weight 65*83 observations. Coefficient of Aberration = 20-54. ... 63*71 " And for a-, — * Former observations on this subject are noticed in Phil. Mag. S. 3. vol. xvi. p. 148 ; vol. xviii. p. 599. — Edit. Royal Astronomical Society. 483 " From the 138 observations made with both circles, Parallax = &96. Weight 77*55 observations. Coefficient of Aberration = 20*48. ... 72*44 " From the 112 observations made with the new circle, Parallax = 6*93. Weight 72*99 observations. Coefficient of Aberration == 20*52. ... 66*27 " If the coefficient of aberration be assumed = 20"*36, as in the Astronomical Society's Catalogue, then, from all the observations with both circles, parallax = 0"*98, the separate results for the two stars being 0"*95 and 1"*00; and, from all the observations with the new circle, parallax = 0"*99, the separate results being 0"*98 and 0"*99. " I believe that the observations are still continued to be made at the Cape ; and I will write to Mr. Maclear immediately, requesting him to send the additional observations. " The two stars appear to be approaching each other, the dif- ference of declination being in 1826 = 18", in 1833 = 15", and in 1840 ss 11". When all the observations are collected, an attempt may be made to determine the orbits, and thence the masses of the stars. " I will as early as possible prepare a detailed memoir on the subject, and transmit it to the Admiralty for presentation to the Astronomical Society. — I am, &c. " T. Henuekson." III. Positions of 78 Fixed Stars contained in the A. S. C, repre- sented by Mr. Baily as not determined with sufficient accuracy, de- duced from Observations made with the Meridian Circle of the Ob- servatory of Kremsmunster. By M. Roller, Director of the Obser- vatory. IV. Observations of Falling Stars made at Hereford on the night of Nov. 12, 1841. By Henry Lawson, Esq. Three observers were employed in watching for these phenomena, from seven o'clock in the evening till half-past four o'clock of the following morning, each taking a distinct portion of the heavens. The whole number observed was 79, and the greatest number ob- served in any one hour was 20, between the hours of three and four in the morning. The result the author considers to be so far satis- factory, that it tends to confirm the fact of the appearance, at about this period, of a greater number of meteors than usual. V. A List of Falling Stars observed Nov. 12, 1841, at St. Helena. By J. H. Lefroy, Esq., R.A., Director of the Magnetic Observatory at Longwood. The whole number observed was 102, between the hours of eight in the evening and five of the following morning. The Greenwich mean solar time of the appearance of each is noted to the nearest second, and the place of its appearance as referred to the bright stars nearest it. The direction of the motion of each is also given, with remarks on its appearance, rapidity, and other circumstances con- nected with the phenomenon. 2K2* 484 London Electrical Society. VI. Path of the Moon's Shadow over the Southern part of France, the North of Italy, and part of Germany, during the Total Eclipse of the Sun on July 7, 1842 (July 8, Civil Time). By Lieutenant W. S. Stratford, R.N. This paper will be found, entire, at p. 346 of the preceding volume. VII. A letter from Professor Hansen, dated March 1, 1842, in ac- knowledgement of the communication of the Foreign Secretary, an- nouncing the award of the Society's Gold Medal at the last Annual General Meeting. " Sir, — I have just now received your letter, by which you an- nounce to me that the Royal Astronomical Society have honoured me with their Gold Medal. I recognise in it a valuable sign of the kind attention of this Society towards me and my labours ; and I beg you to present to them my sincerest thanks. " Pray have the goodness to allow the medal to be sent to M. Prsetorius, Secretary and Librarian of His Royal Highness Prince Albert, who will undertake to send it to me. " Of late my labours in the lunar theory have been considerably advanced. The calculation of the perturbations is finished, and I am now engaged on the calculation of provisional tables for the purpose of comparing my results with observations, and of determining the correction of the elliptic elements which result from them. I am now giving to these tables the necessary extension, that they may afterwards serve as definite tables, after having applied to them the necessary corrections which are required by the new determination of the elliptic elements. To combine with exactness in these tables the most convenient mode of calculating the places of the moon, I have chosen the form that M. Carlini has given to the tables of the sun, as much as it is possible to do so. However, the labour of calculation of the tables themselves is much increased by this arrange- ment. " Repeating my request that you will present my respects to the Royal Astronomical Society, I beg you will accept the sentiment of high consideration with which I have the honour to be, &c. " P. A. Hansen." LONDON ELECTRICAL SOCIETY. [Continued from p. 405.] Nov. 15, 1842. — A note from Mr. "Weekes was read, accompanied by specimens of Acarus galvanicus, developed in solution of ferro- cyanuret of potash. The following notices were communicated by W. G. Lettsom, Esq., M.E.S. : — 1st. Of a new and important application of gal- vanism, by which Jacobi succeeds in extracting gold and silver from their respective ores. 2nd. Of the employment of electro-magnetism for the movement of machinery, in which it is stated that M. Wagner, to whom the German Diet promised 100,000 florins if his plan really succeeded, now reports that he has surmounted all diffi- culties. 3rd. On M. Peclet's new condenser, an instrument calcu- Cambridge Philosophical Society. 485 lated to test the most minute amount of electric tension. It con- sists of an electroscope surmounted by a disc A of glass coated with gold and varnished on its upper surface ; the disc B, varnished on both sides, is placed on this ; it has a glass handle ; the disc C has a handle of glass tube so constructed that the handle of B can pass through it. The delicacy of this instrument was shown by the results which followed the touching of the upper disc with an iron wire once, twice, thrice, four, five, and ten times. A paper by J. P. Gassiot, Esq., F.R.S. M.E.S. &c, was then read, "On the Polarity of the Voltaic Battery." After alluding to the confused descriptions of voltaic batteries which have emanated from the varied modes of arranging the elements, Mr. Gassiot men- tions that the electric tension of the water battery has been de- scribed as differing from that of other battles ; the end we have been accustomed to regard as positive is designated resinous, and the other vitreous ; and this result presented itself to him in his early experiments; upon closer investigation, however, it appears that these conflicting results are due to want of attention to the mode of manipulating with the electroscope. When the excited rod is applied to the side of this instrument, the leaves are affected in a manner precisely the reverse of what happens when it is applied above. The anomalous results occur in the former case, and are due to the effect of the glass rod on the instrument itself, disturbing not only the natural electricity contained in the leaves, but also the surplus acquired by being in contact with, or charged by, the battery. The charge is driven upwards into the plate, and the leaves approach the normal condition. When the rod is applied above the converse occurs. These experiments were made with a new double electro- scope. In conclusion, the author offers a few remarks on electrical nomenclature, and conceives that so long as we are content to con- tinue the terms positive and negative, vitreous and resinous, in ap- plication to the machine, we should not object to use them in reference to the battery. Mr. Walker then concluded the reading of his translation of M. Becquerel's paper " On the Electro-Chemical properties of Gold," in which are given some interesting applications of theory to practice. In extracting ore from a solution of several metals, another solution is made of all the metals but that one ; it is made as nearly as pos- sible of the same specific gravity ; the two form the exciting liquids to a single cell arrangement, and the effect is the release of the metal required. Modifications of the same principle are applied to gild- ing, the author giving the preference to the single cell apparatus. Mr. Weekes's Electro- Meteorological Register for October was read. CAMBRIDGE PHILOSOPHICAL SOCIETY. Nov. 14, 1842. — Professor Fisher read a paper on the Develop- ment of the Spinal or Intervertebral Ganglia, and on various Mal- formations of the Nervous System. This communication was one of 486 Cambridge Philosophical Society. several which Professor Fisher intends to bring forward, the general object of which may be thus expressed : — Researches on certain forms of disease, considered in their con- nexion with the process of formation, the growth and maintenance, and the decline of the human frame. The tendency which the human ceconomy has to accomplish the scheme of its organic existence, is the vital law by which the author has been directed in these researches. Deriving his method from an idea of Galen, Professor Fisher distinguishes in an organ two pro- cesses, the plastic and the functional. Under the first he comprises the formation, the growth, and maintenance of an organ, as well as the alterations of structure, normal or anormal, which it may pre- sent. Under the second, those acts of an organ by which it effects results which have reference to the ceconomy. The physiological portion of Professor Fisher's communication consisted of an account of some embryological researches he had made on the development of the spinal ganglia, in order to throw light on the anomalous conditions which some of them present in Spina bifida, when that disease is limited to the lower region of the spinal column*. Before stating the result of these researches, it may not be inappropriate to mention, that those anomalous con- ditions consist in a coalescence of the last lumbar with the first sacral ganglion, or in a coalescence of some of the sacral ganglia with each other f. In some instances a comparatively strong band is found to pass from the fourth to the fifth lumbar ganglion J. Finding no mention made of the development of the spinal ganglia by the physiologists whose works Professor Fisher con- sulted, he was induced to make researches on the subject, of which the following statement comprises the general results : — That the white, rounded or pyriform bodies which are situated on the side of the furrow which occupies the site of the future spinal cord of the embryon constitutes the rudiments of the spinal or intervertebral • ganglia § . * In every case of Spina bifida which the author has met with affecting the upper part of the spinal column, it was accompanied by a defective formation of the head. f The author has not met with any instance in which this coalescence did not exist. He has now examined sixteen cases. In one case the sub- ject presented a club-foot, on the same side as that on which the two first sacral ganglia were united. He could not recognise any trace of the anterior roots on the united ganglia, but unfortunately the thigh was so lacerated as not to enable him to ascertain with any degree of security whether any part of the nervous or muscular system of the limb was deficient or not. In the same case the fourth sacral ganglia on each side were united into one mass, which was supplied by a single artery. In this case, as indeed in all others which Professor Fisher has observed, the lumbar and sacral nerves presented, as they emerged from their respective foramina, a na- tural appearance. The sacral plexus always seemed to be duly formed. X The author at first thought this band might be a vessel, but careful dissection convinced him that it was continuous with the sheath of the ganglia with which it was connected. Its internal structure presented a granular appearance. § Professor Fisher, at the commencement of these researches, was im- Cambridge Philosophical Society. 487 That whilst the edges of the furrow are closing, a -white line having a filamentous appearance arises between it and each ganglion, the connexion of which with the central parts corresponds with the swellings which give to those parts a sinuous appearance. That another white line arises between the ganglia, and connects them together, so as to cause them to offer collectively an arrange- ment somewhat analogous to that which the ganglia of some inver- tebrate animals present. That another line appears to proceed from each ganglion exter- nally, and to join one which runs parallel with the axis of the body and communicates with the cardiac ganglion. Resuming the pathological part of his subject, Professor Fisher gave the following statement of the views he entertained on the subject of Spina bifida, when that disease is situated in the lumbo- sacral region* : — That the coalescence already described of the ganglia constitutes the primary irregularity to which all the others that the disease pre- sents may be directly or indirectly referred. That this coalescence is favoured by the position those ganglia occupy, and by their volume, the comparative greatness of which may be due to their connexion with the sacral plexus f. That the roots of the nerves appertaining to the united ganglia, by virtue of their passing through the dura mater in one bundle, become so irregularly connected with- the pia mater of the cord, as to give rise to adhesions between that membrane and the arachnoid, and between the latter and the dura mater. That this disordered condition of the pia mater has for its conse- quence the anomalous position of the cord (which always adheres to the inner surface of the posterior wall of the tumour), and even in some instances a deficient development of that organ. That the beginning of the bifid state of the osseous canal corre- sponds above to the point .where the cord becomes attached to the posterior wall of the tumour J. pressed with the feeling, that since his results differed from those of other embryologists, he might be mistaken about the nature of these bodies. He finds, however, that they are confirmed in part by the observations of the late Professor Rolando, and therefore .he has felt more confidence in com- municating them. But whether the observations he has made, or the con- clusions he has drawn from them, be correct or not, the development of the spinal or intervertebral ganglia ought not to be lost sight of. * Although these views coincide with those the author communicated on a previous occasion, and which were recorded in the London and Edin- burgh Philosophical Magazine (vol. x. p. 316), still it may not be con- sidered inappropriate if they be presented again, in association with the additional matter he has brought forward. f The spinal ganglia are, at least about the middle of foetal life, richly supplied with blood-vessels, which may also assist, along with the hyper- trophy of the ganglia, in favouring their coalescence. % In all cases of Spina bifida, the defective formation of the osseous canal corresponds with that of the cord ; where the latter assumes its natural conformation, the canal becomes complete. 488 Intelligence and Miscellaneous Articles. That the branches of the lumbar and sacral vertebrae are not ab- sent in the region affected, but are more or less everted by the pre- sence of the tumour. The researches which Professor Fisher has made on the defective formation of the spinal cord have led him to adopt the following general view regarding the plastic process of that organ : That although the spinal cord possesses, like every other organ, a plastic process peculiar to itself, yet that process may be so influ- enced by the anomalous condition of some of the roots of the spinal nerves as to lead to a partial malformation, or even to a partial de- ficiency of the organ *. The following are the therapeutical inferences that Professor Fisher has drawn from his investigations of the disease in ques- tion : — That as the fluid which the tumour contains is a natural product f, and destined by its pressure to protect the parts with which it is in relation, the removal of it, either by a natural or artificial opening, is to be avoided ; for an opening is not only liable to occasion in- flammation of the lining membrane of the tumour, by the introduc- tion of air and by other causes, but also to allow the continual escape of the fluid, so as to lead to death, either by exhaustion or by depriving the blood of its serous fluid ; for according to an ob- servation recorded by Morgagni, and one made by Professor Fisher himself, the suppression of urinary secretion coincided with the con- stant discharge of the fluid. That if, in puncturing the tumour, the operation be performed in the upper and middle part of it, the spinal cord will almost neces- sarily be wounded. That if the skin covering the tumour be in a natural state, then an equable pressure, in the application of which regard must be had to the situation of the spinal cord, may be used with advantage ; but if the walls of the tumour be thin and membranous, then astringent lotions, tending to corrugate them, may be applied ; in this case, however, the disease generally proves fatal. LXXXIV. Intelligence and Miscellaneous Articles. USE OF SULPHATE OF AMMONIA IN AGRICULTURE^. T^OR the full development of the capacity of the soil, and to •*• afford a greater amount of nitrogen 'than what is af- * The author has applied the idea involved in this view to the considera- tion of Anencephalus, and it is his intention to communicate, on another occasion, the results of his observations on that subject, and on the de- fective formation of the upper part of the spinal column. t The fluid is secreted by the pia mater, but its quantity is probably in- creased by the veins, which often appear unusually distended, a condition that may be owing to the want of resistance in the containing parts. , As regards the author's views on the subject of this secretion, see Phil. Mag. S. 3. vol. x. p. 316. X Communicated by the Engineer of the Chartered Gas Company. Intelligence and Miscellaneous Articles. 489 forded either by the ordinary manure, or the ammonia &c. of the atmosphere, sulphate of ammonia has been introduced, and found to be a most valuable auxiliary, as a top dressing, to the farmer. It has been found to impart a greater degree of fructifica- tion to grass, wheat, and other grain, than any other dressing yet discovered, and at a less cost by 50 per cent. The mode of application as adopted by Mr. C. Hall of Havering-atte-Bower, Essex, is as follows : — Having selected several fields of grass, peas, turneps, and wheat, he had sown broad cast on parts of these fields quan- tities at the cost of 5s. 3d., lis. 4 3- « * g § a s co J5 v« 53 ^ ^ S •« S -•so 2 .§ > l> K ^ Q to V- H s C r K "5 « B b rA *5b^ 3 «0 ';uiod •wb6 •s-a •piKTf •jpiMpUBg •aaiqs -S9Ujijuri(T •jjoiMSiqo uiB6'Sa : uoputrj •3)3IAVpUBg 'Xau5(JO •aiiqs -saujuinQ •urd i •3fDIAliSl[f3 'uiB6'S-a : uopuoi a g O S B'5 Q ■ •urd ?8, •uiH •we ?8 •uojsog §1 O 3 SS •XEJ\[ «>£ •wb6 •jubj -*»g Hwg •tu-B^8 •uojsoa •UTB6 •oos '^oh : uopuo'i JO sXbq CCO I^IO «(Nt^OCOCO(OC51COtN.O)CO->C00105mt00011^.CCCO CVOtO o )'fl'^J'6QCOC3'<1'COCOCOCOCOCOCO',1' o © ~ o I i 1 1 * » if £« A « «jWfl 1'5 d B-| »' :CSCSCSeSg"SS >! rflil-i *tf s^ '^NOCTiW^'fM^i-'-f'f TM(Nif;t:tCCO«Oi lOiCiO»OiO^U5ir3rfi.'QCOW-^,'^'TCOC,O^Tf-' !INWC OiO Hot > OlTj« -c OlO COCO i0iC«X(OtOt^.CC«'*«OI>.^OlO(0»«0DtCC0'l->.'-f' -f(^.i-^^coco IOODOK t^tO C cocococ^Mcococo^coTj-^co^^^^coNNcicococNiiNcocofNc^coa: I CO to ) «3 O ^ O to > JOJOOODOaCD©' j kfj in io ko i* i" NNNOiNonf noncop oi^h •? y ? ? *>*o 9P « (N oo «-h io i->.tN.t^co OOOOOOOO O boOOOiOOOlOlQQOiX OlOlOlcnOiO^OlCjOl HtOK05NO!On>fl i 'OOOOOOOOO' COCOP5C0C0CSC0C0C0C 'OOOliH! ;ot^.cococO'-->o5» r^.o f iok MnniNCOmNWiNWW^CTfNNINCTCTWCTfN rtMaoaoicootflCo^wart'i'^ciO'ooogeo'OcooKWNin SSoS^«w^«««NHprtHjow^«aKp)noctj>tf>aap noOOOo6oboOOOOOOO)0!0;OiO)CCCCOC!(j,.00!OlO!0 IQhOOO ■ in o o ^ffi» ( !M N " t1 ** < ooooo.ooooo< !T3C0C0COCOC0C0CCC0C0( OS CO CO CO © Tji O 0-»C lOiOnTflOCCOODOl-t O'OO O Oj Ol Oi al O Oi CO 0)0)00 0)OiOvO)0 J » Wi t-u i_i) ■■^r. -_. ^Ji 'jj Oi -»C0 t^-'O • IKOlOOiOWMNOMi .WCO p O)! C^* cV C^" CN' CN" Ol' CN (N CO (N CN (M* CNf CNl" CM CN! CN CN (N CN NRA9 CN (N CN CN' CN" CM W 0)0)0)010-2 O^ihiOOiiO l->.'0 IN ~+ iO -* ^* CO CO Tf CS CO tP CO ?1 CN o o o c? o o cocococococococococo won r^.^0 cto-i'CONONrfKK1* ^>»,o ci CTC1CN7',OMCN(pC0pC0-^C0*0!pt>.rN>^-(« ^^ t^i ^i o OiOiO)O)O)O)C0 0)0)OOjOiO)0 ^^ CNCTCSiNCNCNCNCNCNCNCNCO JCOtOO^HCOtOCOOOCO ja)coO)if5(Ooo>-'~ JOOtDfOtOCCn^CTKCO-* cococococococococo.cococo DnTiOpHncowic^iNiNOitoifln v* « (NWO^ ^NpJKO)ip(ptO«5 pi.QO ^-t CT O00000l0)0)0)0l0)0)0)0i0i0)0)0 o C0COCO«COCN.I>.7-tp °. = - 7"'264 - 0"-0621 ja,0- 3"*8665 p, - 0"-S915 ft at - 0-0991 ft -2-2292 ft - 0-1129 ft -0-0022 ft If we assume Encke's second value of the mass of Mercury, namely 4865751' and suPPose H, ft> ft. ft. ft. each = °> then ^ik = -7"-242 - 3"'-867 ft. Now, according to Lindenau, the tropical motion of the node from 1631 to 1802 is 42"'534 annually; hence, with a precession of 50"-21, the annual sidereal motion is 7""676, ... _ o"-434 = - 3"-867 ft ft = + o"-n. With the same data as before I have calculated the motion of the perihelion of Mercuiy, for which I find the following expression : — djLo = + 5"-44335 + 2"-88796ft + 0*86099 ft dt r + 0"-02881 j*3 + l"-59026,<*4+ 0"-07604ft. The mass of Mercury does not enter into this expression. The coefficient of ft is insensible. Supposing now ft, ft, ft, ft, each = 0, ^5= + 5"-44335 + 2"-8876ft. a t Now Lindenau gives for the tropical motion of the perihelion 56"-354 ; or, with a precession of 50"-21, an annual sidereal motion = +6"-144. .-. 6"* 144 = 5"-443 + 2"-888 ft _ 0 -701 _ nv.9, • n,. = = u -Jo. pl 2 -888 The node of Venus, as given in my first note, furnishes us, as- suming Encke's second mass of Mercury, and neglecting the terms which contain ft, ft, ft, ft. ft. with tne equation _ i"-60 = - 5"- 174 ft .-. ft = + 0"'31. Royal Astronomical Society. 531 The three values of /x, are then p, = +o"-n jx, = + 0 -25 JM,1 = +0 '31 or, taking the mean /&, = 0"'22. This, of course, is only given as an approximate estimation ; but it seems difficult to resist the conclusion that the mass of Venus should be augmented by a quantity which cannot be put lower than one-tenth, and is probably considerably larger. An augmentation of one-tenth would make this massogt-0;;o, of two-tenths, - .. . 0 ., ^ . 365308 334806 III. On a Method of Determining the Latitude at Sea. By M . C. L. von Littrow, Adjoint- Astronomer at the Imperial Observatory at Vienna. Communicated by the Rev. W. Whewell, Master of Trinity College, Cambridge. IV. On the Rectification of Equatoreals by Observations of Stars on the Meridian and at an Hour-Angle of Six Hours. By M. C. L. von Littrow. Communicated by the Rev. W. Whewell. V. The Parallax of a Centauri deduced from Mr. Maclear's Ob- servations at the Cape of Good Hope in the years 1839 and 1840. By Professor Henderson. An abstract of the principal contents of this paper will be found in Professor Henderson's letter, contained in the last Monthly No- tice, viz. that for March 1842*. In addition, the author gives the following facts relating to the history of the observations of the star a Centauri. The earliest recorded observations which he has found are those of Richer, at Cayenne, in 1673, and ofHalley, at St. Helena, in 1677 ; but neither of these astronomers mentions it as being double. Feuillee appears to have been the first person who observed it to be double, his observations being made at Conception, in Chili, in July 1709, with a telescope of 18 feet focal length. He estimates their magnitudes as being of the third and fourth, the smaller star being the more westerly, and their distance as equal to the apparent diameter of the smaller star {Journal des Observations Physiques, &c, par Louis Feuillee, tome i. p. 425 ; Paris, 1714). La Condamine observed the star during the expedition to Peru for measuring an arc of the meridian (see Philosophical Transactions for 1 749, p. 142). He estimated it as being of the first magnitude, and recognised its duplicity ; and he remarked that the larger star was northward of the other, and to the east of it. From La Caille's observations in 1751-2, the distance of the two stars appears to have been 22"*5. Maskelyne observed them at St. Helena in 1761 (see Philosophical Transactions for 1764, p. 383), and estimated them as being of the second and fourth magnitudes. Their distance, as observed with a divided object-glass micrometer, he found to be from 15" to 16". From this time to the time of the institution of the Paramatta Observatory, the author has met with no observations of the distance of the stars. Mr. Dunlop, in the years 1 825-6, found * See present volume, p. 482. 2N2 532 Royal Irish Academy. the distance to be 23" (see Memoirs of the Royal Astronomical So- ciety, vol. iii. p. 265), since which time it has been decreasing at the rate of more than half a second per annum. The angle of position scarcely appears to have changed since the time of La Caille ; whence it may be inferred that the relative orbit is seen projected into a straight line, or a very eccentric ellipse ; that an apparent maximum of distance was attained in the end of the last or the beginning of the present century ; and that, about twenty years hence, the stars will probably be seen very near each other, or in apparent contact ; but the data are at present insufficient to give even an approxima- tion to the major axis of the orbit and time of revolution. VI. Observations of the beginning and end of the Solar Eclipse of July 18, 1841. By Dr. Cruikshank. Communicated by G. Innes, Esq. The eclipse was observed at Fyvie Castle, in latitude 57° 26' 40'/-7 north, and longitude 9m 32s* 6 west, where there is a good clock by Hardy and a fine transit instrument. The magnifying power of the telescope used was about thirty. h m 8 s Time of the beginning of the eclipse. 2 15 4 ; uncertain to 10 Time of the end 2 57 30 2. ROYAL IRISH ACADEMY. [Continued from p. 397.] May 24, 1841 (Continued) .—The Rev. Charles Graves, F.T.C.D., read a paper " On the Application of Analysis to spherical Geo- metry." The object of this paper is to investigate and apply to the geo- metry of the sphere, a method strictly analogous to that of rectilinear coordinates employed in plane geometry. Through a point O on the surface of the sphere, which is called the origin, let two fixed quadrantal arcs of great circles O X, O Y be drawn ; then if arcs be drawn from Y and X through any point P on the sphere, and respectively meeting O X and O Y in M and N, the trigonometric tangents of the arcs O M, ON are to be con- sidered as the coordinates of the point P, and denoted by x and y. The fixed arcs may be called arcs of reference. An equation of the first degree between x and y represents a great circle ; an equation of the second degree, a spherical conic ; and, in general, an equation of the nth degree, between the spherical coordinates x and y, repre- sents a curve formed by the intersection of the sphere with a cone of the rath degree, having its vertex at the centre of the sphere. Though it is not easy to establish the general formulae for the transformation of spherical coordinates, they are found to be simple. Let x and y be the coordinates of a point referred to two given arcs, and let x', y' be the coordinates of the same point referred to two new arcs, whose equations as referred to the given arcs are y — y" = m(x — x"), y — y" = m' (x — x'1), x", y" being the coordinates of the new origin ; then the values of Royal Irish Academy. 533 x and y to be used in the transformation of coordinates would be _x"(ax' + by' - 1) x — - — , px' + qy' — 1 y"(cx' + dy'-l) px1 + qy' — 1 In which a, b, c, d, p, and q are functions of m, m', x", and y". It is evident that the degree of the transformed equation in x', y', will be the same as that of the original one in x and y. The great circle represented by the equation a x + /3 y = 1 , meets the arcs of reference in two points, the cotangents of whose distances from the origin are a and /3 ; and, if the arcs of reference meet at right angles, the coordinates of the pole of this great circle are — a, and — /3. It appears from this, that if a and /3, instead of being fixed, are connected by an equation of the first degree, the great circle will turn round a fixed point. And, in general, if a and /3 be connected by an equation of the rath degree, the great circle will envelope a spherical curve to which n tangent arcs may be drawn from the same point. Thus, the fundamental principles of the theory of polar reciprocals present themselves to us in the most ob- vious manner as we enter upon the analytic geometry of the sphere. A spherical curve being represented by an equation between rec- tangular coordinates, the equation of the great circle touching it at the point x' , y' , is (y — y') dx' — (x — x') d y' = 0 ; the equation of the normal arc at the same point is (y ~ V1) [d y' + x' 0' dy' -y'd #')] + (x - x') [dx' + y' (y'dx' - x' dy')~] = 0. Now, if we differentiate this last equation with respect to x' and y' , supposing x and y to be constant, we should find another equation, which, taken along with that of the normal arc, would furnish the values of x and y, the coordinates of the point in which two con- secutive normal arcs intersect : and thus, as in plane geometry, we find the evolute of a spherical curve. Let 2 y be the diametral arc of the circle of the sphere which osculates a spherical curve at the point x\ y', Mr. Graves finds that tan 7 = ± ldx^ + dy^ + (x'dy'-y'dx')^ ~ (1 + xh2 + y'~)i' (dx' d2 y' — dy' d2x') For the rectification and quadrature of a spherical curve given by an equation between rectangular coordinates, the following formulae arc to be employed : — d _ "/dx7'2 + dy'12 + (*' dy' - y' d xj- 1 S~ 1 + x'2 + y'2 y dx and d (area) = — 77- a — -. v ' (1 + x2) Vl + x2 + tf2 In the preceding equations the radius of the sphere has been sup- posed = 1 . 534? Royal Irish Academy. The method of coordinates here employed by Mr. Graves is entirely distinct from that which is developed by Mr. Davies in a paper in the 12th vol. of the Transactions of the Royal Society of Edinburgh. Mr. Graves apprehends, however, that he has been anticipated in the choice of these coordinates by M. Gudermann of Cleves, who is the author of an " Outline of Analytic Spherics," which Mr. Graves has been unable to procure. The President communicated a new demonstration of Fourier's theorem. A letter was read from Professor Holmboe, accompanying his me- moir, De Prised Re Monetarid Norvegia, &c, and requesting to know from the Academy whether any of the coins described in that work are found in Ireland*. July 12f. — Part I. of a " Memoir on the Dialytic Method of Eli- mination," by J. J. Sylvester, Esq., A.M., of Trinity College, Dublin, and Professor of Natural Philosophy in University College, London, was read. The author confines himself in this part to the treatment of two equations, the final and other derivees of which form the subject of investigation. The author was led to reconsider his former labours in this de- partment of the general theory by finding certain results announced by M. Cauchy in L'Institut, March Number of the present year, which flow as obvious and immediate consequences from Mr. Syl- vester's own previously published principles and method. Let there be two equations in x, U = a xn + b x11-1 + c xn~2 + e xn~3 + &c. = 0, V=axw+|3/-1 + X^-2 + &c. =0, and let n = m + i, where ; is zero or any positive value (as may be). Let any such quantities as xr U, xe V, be termed augmentatives of U or V. To obtain the derivee of a degree s units lower than V, we must join s augmentatives of U with s -f < of V. Then out of 2 s-)- i equations x° . U = 0, x\ . U = 0, *2 . U = 0, Xs-1 . U = 0, x°.V = 0, x>.V = 0, *°-.V = 0, ^+*-1.v = o, we may eliminate linearly 2 s -f- i — 1 quantities. Now these equations contain no power of x higher than m _j_ i _j. 5 — 1 ; accordingly, all powers of x, superior torn — s, may be eliminated, and the derivee of the degree (m — s) obtained in its prime form. Thus to obtain the final derivee (which is the derivee of the de- gree zero), we take m augmentatives of U with n of V, and elimi- nate (m + n — 1) quantities, namely, x, x2, x*, up to xm+n~1. * The Committee of Antiquities, having been consulted on this point, reported in the negative. [f An abstract of Prof. Lloyd's paper read on June 14th, will be found in the present volume, p. 395.] Royal Irish Academy. 535 This process, founded upon the dialytic principle, admits of a very simple modification. Let us begin with the case where » = 0, or m = n. Let the augmentatives of U be termed U0, Up U2 U3, .... and of V, V0, V„ V„, V3, .... the equation themselves being written \J = axn + bxn-1 + cxn~2 + &c. V = a'xn + b'xn~l + c'x"-2 + &c. It will readily be seen that a' . U0 — a . V0, (i'U0-*V0) + (a'U1-aV1), (c'.U0-c.V0) + (J'Ul-6VI) + («'Us-aVi),&c. will be each linearly independent functions of x, x%, xm~l, no higher power of x remaining. Whence it follows, that to obtain a derivee of the degree (m — s) in its prime form, we have only to employ the s of those which occur first in order, and amongst them eliminate xm~~l, xm~2, . . . . xm~~ *+*. Thus, to obtain the final de- rivee, we must make use of n, that is, the entire number of them. Now, let us suppose that i is not zero, but m = n — i. The equation V may be conceived to be of n instead of m dimensions, if we write it under the form 0 . xn + 0 . xn~l + 0 . **-* + + 0 , xm+1 + axm + (3x™-l + 8ic. = 0. and we are able to apply the same method as above ; but as the first / of the coefficients in the equation above written are zero, the first i of the quantities (a' V0-a V0), (b> U0 - b V0) + («' U, - a V,), &c. may be read simply - a . V0, -J.V0-oV„ - c V0 - 6 V, - a V2, &c. and evidently their office can be supplied by the simple augmenta- tives themselves, V0 = 0, V,=0, V9 = 0.... ^ = 0; and thus < letters, which otherwise would be irrelevant, fall out of the several derivees. The author then proceeds with remarks upon the general theory of simple equations, and shows how by virtue of that theory his me- thod contains a solution of the identity Xr.U + Yr.V = Dr; where Dr is a derivee of the rth degree of U and V, and accordingly, Xr of the form X + px + vx- + + flaB»-r-1, and Yr of the form I + mx + .. .. + txn~r-1, and accounts a priori for the fact of not more than (» — r) simple equations being required for the determination of the (m -f- n — 2 r) quantities A, p, v, &c. /, m, n, &c, by exhibiting these latter as known 536 Royal Irish Academy. linear functions of no more than (n — r) unknown quantities left to be determined. . Upon this remarkable relation may be constructed a method well adapted for the expeditious computation of numerical values of the different derivees. He next, as a point of curiosity, exhibits the values of the secon- dary functions, a' . U0 — a V0, b' .V0-bV0 + n'.U1-aV„ c' . U0 - c . V0 + b' . U, - b V, + a' . U2 - a V2> &c. under the form of symmetric functions of the roots of the equations U = 0, V = 0, by aid of the theorems developed in the London and Edinburgh Philosophical Magazine, December 1839, and after- wards proceeds to a more close examination of the final derivee re- sulting from two equations each of the same (any given) degree. He conceives a number of cubic blocks each of which has two numbers, termed its characteristics, inscribed upon one of its faces, upon which the value of such a block (itself called an element) de- pends. For instance, the value of the element, whose characteristics are r, s, is the difference between two products : the one of the coefficient rth in order occurring in the polynomial U, by that which comes sth in order in V ; the other product is that of the coefficient sth. in order of the polynomial V, by that rth in order of U ; so that if the degree of each equation be n, there will be altogether i — — — I such m elements. The blocks are formed into squares or flats {plafonds) of which the number is — or — — — , according as n is even or odd. The first of these contains n blanks in a side, the next (n — 2), the next (n — 4), till finally we reach a square of four blocks or of one, ac- cording as n is even or odd. These flats are laid upon one another , so as to form a regularly ascending pyramid, of which the two dia- gonal planes are termed the planes of separation and symmetry re- spectively. The former divides the pyramid into two halves, such that no element on the one side of it is the same as that of any block in the other. The plane of symmetry, as the name denotes, divides the pyramid into two exactly similar parts ; it being a rule, that all elements lying in any given line of a square {plafond) parallel to the plane of separation are identical; moreover, the sum of the characteristics is the same, for all elements lying anywhere in a plane parallel to that of separation. All the terms in the final derivee are made up by multiplying n elements of the pile together, under the sole restriction, that no two or more terms of the said product shall lie in any one plane out of the two sets of planes perpendicular to the sides of the squares. The sign of any such product is determined by the places of either set of planes parallel to a side of the squares and to one another, in which the elements composing it may be conceived to lie. lloyal Irish Academy. 537 The author then enters into a disquisition relating to the number of terras which will appear in the final derivee, and concludes this first part with the statement of two general canons, each of which affords as many tests for determining whether a prepared combina- tion of coefficients can enter into the final derivee of any number of equations as there are units in that number, but so connected as together only to afford double that number, less one of independent conditions. The first of these canons refers simply to the number of letters drawn out of each of the given equations (supposed homogeneous) ; the second to what he proposes to call the weight of every term in the derivee in respect to each of the variables which are to be elimi- nated. The author subjoins, for the purpose of conveying a more accurate conception of his Pyramid of derivation, examples of the mode in which it is constructed. When n = 1 there is one flat, viz. When n = 2 there is one flat, viz. 1,2 2, 3 2, 4 2, 4 3,4 Let n as 3, there will be two flats: Let n = 4, there will still be two flats only : 2, 3 2,4 2, 4 3,4 1,2 1,3 1,4 1,3 1,4 2, 4 1,4 2, 4 3,4 1,2 1,3 1,4 1,5 1,3 1,4 1,5 2,5 1,4 1,5 2, 5 3, 5 1,5 2, 5 3, 5 4,5 538 Royal Irish Academy. Let n = 5, there will be three flats : 3,4 2, 3 2, 4 2, 5 2, 4 2,5 3,5 2, 5 3, 5 4,5 1,2 1,3 1,4 1,5 1,6 1,3 1,4 1,5 1,6 2,6 1,4 1,5 1,6 2,6 3,6 1,5 1,6 2,6 3,6 4,6 1,6 2,6 3,6 4,6 5,6 Royal Irish Academy, Let n = 6, there will be three flats : 539 3,4 3,5 3,5 4,5 2,3 2,4 2,5 2,6 2,4 2,5 2,6 3,6 2,5 2,6 3,6 4,6 2,6 3,6 4; 6 5,6 1,2 1,3 1,4 1,5 1,6 1,7 1,3 1,4 1,5 1,6 1,7 2,7 1,4 1,5 1,6 1,7 2,7 3,7 1,5 1,6 1,7 2,7 3,7 4,7 1,6 1,7 2,7 3,7 4,7 5,7 1,7 2,7 3,7 4,7 5,7 6,7 Thus the work of computation reduces itself merely to calculating n . — — — elements, or the n (n + 1) cross-products out of which they are constituted, and combining them factorially after that law of the pyramid, to which allusion has been already made. 540 Geological Society : Mr. Strickland GEOLOGICAL SOCIETY. [Continued from p. 378.] Dec. 15, A paper "On the Glacia- diluvial Phenomena in Snow- 1841. -^*- donia and the adjacent parts of North Wales," by the Rev. Prof. Buckland, D.D., F.G.S., &c. was first read. A paper was afterwards read, " On the occurrence of the Bristol Bone-Bed in the Lower Lias near Tewkesbury," by Hugh Edwin Strickland, Esq., F.G.S. After alluding to the occurrence of the bone-bed at various places between Westbury and Watchett, also at Golden Cliff and St. Hilaiy in Glamorganshire, and at Axmouth, Mr. Strickland proceeds to describe its characters at three newly-discovered localities, many miles to the north of the points previously known, namely, Coomb Hill, between Tewkesbury and Gloucester, Wainlode Cliff, and Bushley. 1. Coomb Hill, four miles south of Teiokesbury* . — In lowering the road through the lias escarpment during the summer of 1841 a con- siderable surface of the bone-bed was exposed, and its contents were rescued from destruction by Mr. Dudfield of Tewkesbury. The fol- lowing section is given by Mr. Strickland : — Ft. in. 1 . Yellow clay 2 0 2. Lias limestone 0 3 3. Yellow clay 5 0 4. Nodules of lias limestone 0 6 5. Brown clay 14 0 6. Impure pyritic limestone with Pectens and small bivalves 0 6 7. Black laminated clay 8 0 8. Hard, grey pyritic limestone 0 2 9. Black laminated clay 1 0 10. Greyish sandstone 0 2 1 1 . Black laminated clay 1 6 12. Bone-bed 0 1 13. Black laminated clay 3 6 14. Compact, angular, greenish marl 25 0 15. Red marl 3 0 Dip about 12° east. 64 8 The bone-bed, No. 12, rarely exceeds one inch in thickness, and frequently thins out to less than a quarter of an inch. It consists in some places chiefly of scales, teeth and bones of fishes, and small coprolites cemented by iron pyrites, but in others the organic re- mains are rare, and are replaced by a whitish micaceous sandstone. The osseous fragments, Mr. Strickland states, have the appearance of having been washed into the hollows of a rippled surface of clay, * Mr. Murchison has noticed the section formerly exposed in this escarpment, but at the time he examined the district, Mr. Strickland says, the banks were obscured by dehris, and the bone-bed did not attract his attention. See Mr. Murchison's Account of the Geology of Cheltenham, p. 24, plate, fig. 1, and Silurian System, pp. 20, 29, pi. 29, fig. 1. on the Bone-bed in the Lias near Texvlcesbury. 541 and of having been subjected to slight mechanical action. The ex- istence of gentle currents is further proved, he says, by the presence of small rounded pebbles of white quartz, a substance of very rare occurrence in the liassic series. The only shell found in the bed at Coomb Hill is a smooth bivalve, but too imperfect to be generically determined. 2. Wainlode Cliff, three miles west -south-west from Coomb Hill. — The section exposed at this locality has been laid open by the action of the Severn, and consists of the following beds : — Ft. in. 1 . Black laminated clay, inclosing, near the top, a band of lias limestone with Ostrese 22 0 2. Slaty calcareous sandstone, with a peculiar small species of Pecten 0 4 3. Black laminated clay 9 0 4. Bone-bed, passing into white sandstone 0 3 5. Black laminated clay 2 0 6. Light green angular marl 23 0 7. Red marls, with zones of a greenish colour . . 42 0 Dip very slight to the south. 98 7 The bone-bed is far less rich in organic remains, accumulations of fragments of bones and coprolites occurring at rare intervals ; and its prevailing character is that of a fissile, white, micaceous sand- stone, sometimes acquiring a flinty hardness. The upper surface of the bed is ripple-marked, and in some cases presents impressions considered by Mr. Strickland to have been probably made by the claws of Crustacea. A small bivalve is also the only shell found in the bed. The stratum No. 2, the author says, is evidently a con- tinuation of No. 6. of the Coomb Hill section. 3. Bushley, two miles and a half west of Tewkesbury. — The inter- section of the lias escarpment by the Ledbury road near Bushley afforded Mr. Strickland the following section : — Ft. in. 1 . Black laminated clay, about 10 0 2. Lias limestone 0 4 3. Black laminated clay ! 6 0 4. Compact slaty bed with numerous small bi- valves, and the Pecten of Wainlode and Coomb Hill 0 3 5. Black laminated clay 9 0 6. White micaceous sandstone, with impressions of two species of bivalve shells 1 0 7. Black laminated clay 2 6 8. Greenish marl, about 20 0 9. Red marl '. — - Dip about 8° east. 49 1 The sandstone bed, No. 6, agreeing precisely with that at Wain- lode Cliff, Mr. Strickland does not hesitate to consider it the repre- sentative of the bone-bed, though organic remains are wanting ; and he points out the identity of the stratum No. 4. with the beds Nos. 542 Geological Society : Dr. E. Moore on Fossil Bones 2. and 6. of the preceding sections. The author also refers to the railway section near Droitwich*, and identifies with the bone-bed the two-feet band of white micaceous sandstone six feet above the top of the green marl, as it contains the same indeterminable small bivalve. He has also examined sections of the lias escarpment at Norton near Kempsey, and Cracombe Hill near Evesham, and has invariably detected, a few feet above the. base of the lias clay, a thin band of white sandstone containing the same shell. The bone-bed at Axmouth, Watchett, Aust, Westbury, and other southern localities, occupies precisely the same geological position, or a few feet above the top of the greenish marls which terminate the New Red system, though much more rich in organic remains ; and Mr. Strickland draws attention to this remarkable instance of a very thin stratum ranging over a distance of about 112 miles. The great abundance of fossils in some parts of this stratum the author considers an indication that a much longer period probably elapsed during its deposition, either on account of the clearness of the water or of a gentle current which prevented the precipitation of muddy particles, than while an equal thickness of the less fossiliferous clays above or below it was accumulated. The list of organic remains given in the paper includes scales of Gyrolepis tenuistriatus ? and Amblyurus ; teeth of Saurichthys api- calis, Acrodus minimus, Hybodus minor, Pycnodus ? ; others bearing an analogy to those of Sargus ; portion of a tooth with two finely serrated edges, and considered as probably belonging to a saurian allied to the genus Palceosaurus ; a tooth of Hybodus De la Bechei (i?. medius, Ag.), a ray of Nemacanthus monilifer ; small vertebra of a fish ; bones of an Ichthyosaurus ; coprolites ; and the casts of the bivalve before mentioned. Mr. Strickland next alludes to Sir Philip Egerton's paper on the Ichthyolites of the bone-bed f, and he states that the bed cannot be of the age of the muschelkalk, as it overlies the red and green marls, which he considers to have been satisfactorily shown to be equivalent to the Keuper sandstein of Germany ; and that the occurrence of muschelkalk fishes associated with lias Ichthy- olites only justifies the inference that certain species survived from the period of the muschelkalk to that of the bone-bed. There are yet stronger grounds, Mr. Strickland states, for placing the bone-bed in the liassic series in the remarkable change a few feet below it, from black laminated clay to compact " angular " marl, greenish in the upper part and red below ; and he adds, the trans- ition is so sudden that it may be defined within the eighth of an inch ; moreover no marl occurs above the line nor black laminated clay below it ; and although, in the case of the bone bed, an arena- ceous deposit similar to the Keuper sandstein is repeated, accom- panied by some triassic organic remains, yet, the author adds, this does not invalidate the evidence of the commencement of a new order of things, or of an interesting passage into the liassic series from the triassic system. [* Phil. Mag. S. 3., vol. xviil, p. 523.] [f lb. vol. xix., p. 522.] on the surface of a raised Beach near Plymouth. 543 Lastly, Mr. Strickland notices the occurrence of precisely analo- gous bone-beds in the Upper Ludlow rock, described by Mr. Mur- chison in the ' Silurian System' (p. 198), and in Caldy Island, near the junction of the carboniferous limestone with the old red sand- stone ; and he offers some remarks on the bone-beds being found in all the three cases near the passage from one great geological system of rocks to another. January 5, 1842. — " A Notice on the Fossil Bones found on the surface of a raised Beach at the Hoe near Plymouth," by Edward Moore, M.D., F.L.S., was. first read. At the Meeting of the British Association at Plymouth, Dr. Moore read a paper on the same subject as that which forms part of the present communication*. In this notice he first alludes to the discovery of the beach by the Rev. R. Hennah in 1827f, and to Mr. De la Beche's account of numerous anciently raised beaches in Devon and Cornwall J ; he then briefly describes the characters of the beach, its position in a hollow in the limestone rock, 100 feet wide, 70 feet deep, and, at its base, 35 feet above the present high water mark. He also notices a projecting ledge of limestone stretching several hundred feet southward from this spot, and which sustained a mass of sand, with rolled pebbles and blocks, some of them two or three feet in circumference, and forming a hill twenty to twenty-five feet high, containing patches of loose sand with fragments of Patella and Buccinum. It was, says the author, easily traced by several patches along the rocks, and proved, by its structure and contents, to be a continuation of the same beach. Dr. Moore likewise briefly describes another deposit 100 yards westward of the beach, and at a greater elevation, being 88 feet above high water, 50 feet in extent, and 10 in thickness, covered irregularly by soil. The animal remains more particularly enumerated by Dr. Moore consist of a molar and part of the jaw of a young elephant ; a femur of a rhinoceros ; maxillary bones of a bear, with the malar and pala- tine processes, and two teeth in each ; an entire right lower ramus with teeth and tusks, the latter much worn ; four separate tusks ; several fragments of long bones ; fragments of jaws of the horse con- taining teeth, numerous loose teeth, portions of long bones, and two caudal vertebrae ; likewise portions of a deer's jaw containing teeth. The quantity of the bones which has been found is stated to be equal to several bushels. The vertebrae of a whale, much rounded, were also discovered, with undeterminable portions of ribs. The animals to which the above remains belonged, are considered by Dr. Moore to have coexisted with those which inhabited the caves of Devon- shire. The author then enters upon a defence of the opinions contained * Athenamm, No. 721, and the volume of Reports of the British Asso- ciation for 1841, Trans, of the Sections, p. C2 (published 1842). f See also " A Succinct Account of the Lime Rocks of Plymouth," by the Rev. R. Hennah, 1822, p. 58. X Manual of Geology, 3rd Edition, p. 173, 1833; also Report on the Geology of Cornwall and Devon, p. 423, 1839. 544 Geological Society : Mr. Colthurst on Contortions in his paper read at Plymouth, respecting the mode of accumulation of the bones. He states that these osseous remains cannot have been derived from the emptying of some cave, because the mass of superincumbent matter which has been removed from above the beach proves that the bones must have been deposited where they were found at a very ancient period, and long before they could have been affected by human agency. There are also no known caves containing bones sufficiently near. On the contrary, says Dr. Moore, if the sea was at one time at the level indicated by the beach, the Hoe must have been an island accessible by animals at low water, and there appears no obstacle to the supposition that the bears might have selected the beach to devour their prey ; and the stranded whale may have added to the banquet. Whether the bones were drifted or not, their occurrence on the top of the beach, and not in it, prevents, the author says, any identity of time in their origin ; but that the beach previously existed, and was of marine origin, is proved by the resemblance of the deposit to a modern beach, and its containing sea-shells of the existing period, although few in number. That the deposit is not the result of glacial action, the author observes, is probable from the want of any indication of such action in the neighbouring district ; and though he does not presume to assert that this may not be a cause of drift generally, and even of the upper deposit in the same locality, yet he contends that the dissimilarity in the composition of the lower deposit sustains him in the supposition of its being of different origin, and really a deposit from the sea. Lastly, Dr. Moore, in reference to the present posi- tion of the beach far above any point attained by the sea during the greatest storms, states that the deposit must have been elevated by natural causes ; and that, however uncertain the exact period of such an event, it seems to have occurred at a time probably more recent than the epoch when the extinct animals disappeared. Appended to the paper, is a notice of a specimen of perforated limestone taken from the Hoe Lake quarries, eighty- five feet above the present level of high water, and Dr. Moore maintains his belief that the perforations were formed by Pholades, and not by snails. A paper was next read, entitled " An Account of the Contortions and Faults produced in the Strata underneath and adjacent to the great Embankment across the Valley of the Brent, on the Great Western Railway," by J. Colthurst, Esq. ; communicated by George Bellas Greenough, Esq., F.G.S. The author was induced to lay this paper before the Society, be- cause he conceives, that, in the phenomena exhibited by the sub- sidence in the Brent embankment, there may be found the cause of many of the contortions, faults and dislocations of strata, especially among sedimentary rocks, and which are commonly attributed to the agency of forces acting from below rather than to pressure from without. The embankment is fifty-four feet in height, and rests on vegetable soil, beneath which are four feet of alluvial clay ; then occurs a bed produced in the strata beneath an embankment. 5^5 of gravel varying from ten to three feet in thickness, hut which thins out in some places, and under it is the regular London clay, traversed in almost every direction by slimy joints. The surface of the country gradually slopes towards the Brent, the difference of level between the south side of the embankment and the Brent being about twenty feet. On the night of the 21st of May 1837 the embankment began to settle, and in the morning it was found that the foundation had given way, and that on the south side, or towards the Brent, a mass of ground, fifty feet long and fifteen feet wide, had protruded from under the earthwork. During the four succeeding months this mass con- tinued to increase in dimensions, and the disturbance to extend, so that the surface, for a considerable distance from the base of the embankment, had assumed an undulated outline, and the subjacent beds, where cut into, exhibited corresponding curvatures, overlappings and cracks, the whole of which are described in the memoir, but can- not be rendered intelligible without diagrams. In the embankment itself the symptoms of failure were confined to a settlement of about fifteen feet, and a large fissure near the top, on the side opposite to that where the foundation had yielded, and which extended the whole length of the slip. To this fissure, and its dip towards the disturb- ance at the base of the embankment, the author particularly directs attention, as he infers from it the nature and inclination of a fault exhibited in the diagrams which illustrate the memoir. At the end of twelve additional months, during which the embank- ment continued to slip, and the disturbance at the base to increase, Mr. Brunei directed a supplementary earthwork or terrace to be thrown down upon the swollen surface, and it was an effectual re- medy. Up to this time the total subsidence had exceeded thirty feet ; and the swollen ground, which extended nearly 400 feet in length, and from seventy to eighty feet in width, had attained an average height of ten feet, with a horizontal motion of fifteen feet ; but the general disturbance ranged to a distance of 220 feet from the foot of the slope, or to the Brent, the bank of which was forced five feet forwards : the faults varied from thirty feet to two feet, and the contortions had attained a curvature, the semi- axis of which was in many places eight feet. The author then dwells on the magnitude of the disturbance, and on the effects which may have been produced in the strata com- posing the earth's surface, by pressure from above. He says, that in consequence of the great inequality in the thickness of the sedimen- tary rocks, due to the conditions under which they were deposited, great inequality of pressure must have arisen, and consequently con- tortions and faults have been produced, varying in amount according to the thickness and the degree of consolidation in the strata them- selves. In support of his argument, the author quotes a passage contained in Mr. Greenough's 'Critical Examination of the Principles of Geology,' and which asks the question whether contortions may not have taken place where clay alternates with limestone or silex, in consequence of an unequal rate of consolidation (p. 77). The author also alludes to the theory of Sir James Hall, but chiefly to Phil, Mag. S. 3. No. U 1 , SuppU Vol. 2 1 . 2 O 54:6 Geological Society : Mr. Pearce on Ammonites^ prevent its being " mixed up in any way with the subject of this paper, or the inferences it contains ; " and lastly, he wishes it may be clearly understood, that while he advocates the explanation of many geolo- gical phenomena by means of pressure from without, he does not propose that all geological disturbance should be attributed to it ; nor does he deny that many, and more especially the most consider- able, irregularities in the structure of the earth may and must be assigned to other causes. " Notice on the occurrence of Plants in the Plastic Clay of the Hampshire Coast," by the Rev. P. B. Brodie, F.G.S., was then read. The cliffs to the east and west of Bournemouth are composed of horizontal strata belonging to the plastic clay formation. East of the town they consist of white and yellow sands, the former con- taining fragments of wood. Further along the shore the cliffs arc higher, and beds of clay full of vegetable remains appear under the sands. About half a mile beyond, a stratum of fine white sand, three or four feet thick, situated near the middle of the cliffs, con- tains impressions of ferns ; and a layer of sand and clay is full of small leaves. The subjacent strata of clay are separated by thin layers of vegetable matter. Somewhat further, beds of white and yellow sand and sandy clay abound with beautiful leaves, and the surface of the strata is in some places covered with a thin layer of iron-sand containing impressions of ferns. In most cases, the vari- ous-coloured sands are divided by beds of clay, and their fossil con- tents are distributed in layers at rather distant intervals. Mr. Brodie did not discover any shells. Several of the fossil plants are stated by the author to belong to the Lauracea and Amentacea; but he says that these, as well as others which he arranges among the Characea and Cryptogami, and some of which he has not determined the characters, are all geaerically distinct from any British plant, and belong to those of a warmer climate. When the sandstone is freshly broken the epidermis of the fossil frequently peels off, leaving the impression of only the fibres. These remains often form masses of some thickness ; and, from their state of preservation, must, the author states, have been deposited tranquilly beneath the waters. A.paper " On the Mouths of Ammonites, and on Fossils contained in laminated beds of the Oxford Clay, discovered in cutting the Great "Western Railway, near Christian Malford in Wiltshire." By J. Chaning Pearce, Esq., F.G.S., was lastly read. Mr. Pearce commences by stating, that his attention was first di- rected to this part of the railway by the impression of a crushed Ammonite procured at Cheltenham in April 1841, but that he was prevented from examining the locality for three or four months. The following section of the beds is given by Mr. Pearce : — 1 . Alluvial soil 2 feet. 2. Gravel 8 ... 3. Four or five bands of laminated clay, al- ternating with sandy clay, almost en- tirely composed of broken shells. ... 6 ... 4. Clay, containing Gryphaa bilobata. and on Fossils in the Oxford Clay. 54-7 The objects of the author are, first, to draw attention to the organic bodies discovered in the laminated clay ; and secondly, to describe the various forms which the mouth of the Ammonite assumes in different species and in different stages of growth in the same species. The fossils obtained from the laminated clay are stated to be as follows : — 1. A succulent plant. 2. Lignite, with oysters sometimes affixed to it. 3. Crustaceans, supposed to have inhabited the dead shell of the Ammonite*. The specimen described is stated to have a finely tuberculated and delicately thin covering ; the tail to have the appearance of being divided into three portions, finely corrugated towards their edges ; the body to have on each side internally five or more processes ; and the head to be furnished with several short arms and two long ones jointed a little above the head and ter- minated in two claws, the longer being serrated on its inner edge. 4. Another allied crustacean is stated to have also an extremely thin and finely tuberculated covering ; to be furnished with two long arms of similar shape, each terminated at its extremity by one claw, and two others projecting from about the centre ; and passing off poste- riorly are two fan-like processes of similar shape. 5. Trigonellites, two species. 6. One valve of a Pollicipes. 7. The remains of an animal considered to have been probably allied to a Sepia. 8. Shells of the genera Unio, Cyclas, Astarte, Avicula, Gervilla, Pinna, Nu- cula, Rostellaria, Turritella, Ammonites f, Belemnites, and an animal to which he has applied (since the paper was read) the name of Be- lemnotheutis. In describing the last fossil, he states that the lower part is conical, blunt at the apex, and chambered internally like the alveolus of a Belemnite, with an oval siphunculus near the edge of the chambers ; that it has a brown thick shelly covering which gra- dually becomes thinner towards the superior part ; that immediately above the chambers is an ink-bag resting on what resembles the upper part of a sepiostaire, and composed of a yellow substance finely striated transversely, being formed of laminae of unequal den- sity ; that in some specimens, broken longitudinally through the middle, are exposed long, flat, narrow processes of a different struc- ture ; that immediately beneath the superior contraction are two long feather-like processes, and one or more which are short, indica- ting, the author thinks, probably the situation of the mouth. With reference to the first part of the paper, Mr. Pearce also notices an animal allied to Sepia or Loligo, one side being covered by a pen resembling that of the Loligo, and having immediately underneath it, at the junction of the middle with the lower third, an ink-bag * To this organic body Mr. Pearce has given since the paper was read the name of Ammonicolax. \ Since the paper was written Mr. Pearce has consulted Mr. Pratt's ac- count in the Annals of Natural History for November 1841, of Oxford clay Ammonites, and ascertained that he possesses [A. Lonsdalii, A. Brightii], \_A. Gutielmi, A. ElizabethecB], A. Comptoni, and A. Konigii. The fossils included between brackets the author considers to belong to one species. 2 02 54-8 Geological Society : Mr. Lyell on the Recession resting on what resembles a sepiostaire. He mentions likewise ten or twelve species of fishes, but without giving names ; also coprolites. 2. Respecting the form of the mouth of the Ammonites and the changes at different periods of growth, Mr. Pearce states his belief, that the terminal lip or mouth has a different shape in the young shell of almost every species, but assumes in the old a straight out- line, and that he has been aware of this circumstance several years. Of cases of young shells with differently shaped lips, he mentions Ammonites Brongniarti (Inf. oolite), A. sublcevis (Oxf. clay), A. ob- tusus (Lias), A. Kamigii (Kelloway Rock, the mature shell is stated to have a straight mouth), A. Calloviensis (Kelloway Rock, the lip of the old shell is stated to be slightly contracted and to terminate with gently undulating sides), A. Walcottii (Lias), and A. Goodhalli, fur- nished in the mature state with a single horn-like projection at the front of the mouth. In addition to these species he enumerates those noticed in the preceding part of the paper. Mr. Pearce is further of opinion that at different periods of the formation of the shell the la- teral processes were absorbed and reproduced, and that therefore they are found in various stages of growth, but are invariably want- ing in the mature shell. In some species in which the successive mouths were much contracted or expanded, the new shell the author says was continued without the absorption of the lip, leaving a highly projecting rib or a deep furrow*. After a careful examination of upwards of twenty species in his collection, with perfect mouths of all ages and from different strata, not including the Oxford clay, Mr. Pearce has found the external chamber to vary considerably in extent, occupying in some speci- mens the whole of the last whorl, but in others less than one-third, and without reference to age or species ; and he therefore suggests that the young animal of the Ammonite filled the whole of the outer chamber, extending also to the extreme points of the lateral pro- cesses in those species which were provided with them ; and thereby not only received support but afforded protection to a portion of the shell extremely liable to injury. In old individuals he is of opinion that the animal when quiescent was entirely contained within the last chamber. Jan. 19th. — "A Memoir on the Recession of the Falls of Niagara," by Charles Lyell, Esq., V.P.G.S., was read. The general features of the physical geography of the district tra- versed by the Niagara between Lakes Erie and Ontario, Mr. Lyell says, have been described with a considerable approach to accuracy by several writers. Prof. Eaton, in a small work published in 1 824 f, gives a correct section of the formations between Lewistown and the Falls of Niagara, and also refutes the hypothesis of the Lewis- town escarpment being due to a fault by an exposition of the true * The author was not acquainted with M. Al. d'Orbigny's work, Pal. Francalse, when he wrote the paper, and was not aware of the views given in it respecting the mouth of the Ammonite. f Mr. Lyell's attention was called to this work by Mr. Conrad. of the Falls of Niagara. 549 structure of the country. Mr. R. Bakewell in 1830*, published an account of the country adjacent to the Falls, and Mr. De la Beche in 1831 f» endeavoured to point out the gradual manner in which the receding Falls, if they should ever reach Lake Erie, would dis- charge the waters of the lake; Prof. D. Rogers also in 1835 J showed distinctly, that, as the Falls retrograde, they would cut through rocks entirely distinct from those over which the waters are now precipitated, and correctly represents the superior limestone at Buffalo as newer than the limestone of the Falls, though he omits the intervening saliferous formation. Mr. Conrad likewise, in his Report for 1837 §, first assigned all the formations of the country to the Silurian system ; but to Mr. James Hall (1838) || is due the merit of having shown the true geological succession of rocks of the di- strict. The contents of the memoir may be divided into two parts : I. an account of the successive strata of the Niagara district ; and II. a description of the phenomena exhibited by the Falls. I. His sketch of the geology of the district, the author states, is derived either from the published surveys of Mr. Hall, or from the information he obtained while travelling with that gentleman in the State of New York during the autumn of 1841 ; and he acknow- ledges the great advantage he derived from the facilities thus afforded him. The strata between Lakes Erie and Ontario appear to belong to the middle and lower portions of the English Silurian system, and they are divisible into the following five principal formations: 1st. the Helderberg limestone ; 2nd, the Onondago salt group ; 3rd, the Niagara group ; 4th, the Protean group ; and 5th, the Ontario group, 1. The Helderberg limestone, which has derived its designation from the range of mountains of the same name, and is the newest formation of the country, is exposed where the Niagara flows out of Lake Erie, and on account of the organic remains with which it abounds, it is considered to be the equivalent of the Wenlock rocks of Mr. Murchison's Silunan system. The correctness of this stra- tigraphical position Mr. Lyell has verified by an examination of the succession of formations from the coal-field on the borders of Penn- sylvania to the group in question, the intervening deposits consist- ing, first, of old red sandstone, having at its bottom a large develop- ment of shales and sandstones called the Chemung and Ithaca for- mations, but containing organic remains which resemble those of the Devonian system; and then 1000 feet of Ludlowville shales with fossils analogous to those of the Ludlow rocks of Mr. Murchison. The superposition of this vast horizontal series is beautifully ex- posed in the banks of the Genessee and other rivers ; and near Le Roy as well as elsewhere, the Helderberg limestones crop out from be- neath them. On account of the middle portion containing nodules * Loudon's Magazine of Natural History, 1830. f Manual ofGeology, three editions, 1831, p. 55; 1832, p. 55; 1833, p. 60. X Silliman's Journal, vol. xxvii. p. 326. § States' Report of the Geology of NewYork. || Geological Report of the State of New York for 1838. 550 Geological Society : Mr. Lyell on the Recession and layers of chert, the whole deposit was first called the corni- tiferous formation by Prof. Eaton. In this part of the State of New York, and still further to the west, in Upper Canada, the limestone is only 50 feet thick, whereas at Schoharie in the Helderberg moun- tains, 300 miles to the eastward, its thickness is 300 feet. 2. The Onondago salt group. — This series of beds, Mr. Lyell says, is extremely unlike any described member of the European Silurian group. With the exception of a stratum of limestone at the top containing Cytherina, it consists of red and green marls with beds of gypsum, the former being undistinguishable from the marls of the new red system of England ; and they are also destitute of fossils. Salt springs are of frequent occurrence, but no rock salt has been disco- vered in the group. The breadth of the zone of country occupied by the deposit is not less than 16 miles, and Mr. Hall infers from it and the slight southerly dip of the strata, that the entire thickness in the neighbourhood of the Niagara is at least 800 feet, an estimate con- firmed by the nearest sections eastward of the river. In some parts of the State of New York the thickness is not less than 1000 feet. Along the Niagara the formation has been greatly denuded, and is covered by superficial drift, except at a few places. 3. The Niagara group. — This series of beds commences near the rapids, above the great cataract. It comprises, 1st, the Niagara, or Lockport limestone, and 2ndly, the Niagara, or Rochester shale ; and it contains in both divisions fossils identical with those of the Wenlock limestone of England, with others peculiar to North Ame- rica. The limestone at the rapids and the Falls is 120 feet thick ; the upper 40 feet, being thin-bedded, have given way to the frost and the action of the stream ; but the lower 80 feet, being massive, forms at the cataract a precipice, beneath which occurs the shale, also 80 feet thick. 4. The Protean group. — Under the water at the base of the Falls crop out the higher beds of this formation, the name of which has been derived from the variable nature of its component strata. In the district more particularly described in this paper the group is only 30 feet thick, but farther to the eastward it attains thrice those dimensions. On the Niagara it consists of 25 feet of hard limestone, resting on 4 feet of shale ; while at Rochester, eighty miles to the eastward, it comprises, among other beds, a dark shale with grapto- lites, or fossiliferous iron ore, and beneath them a limestone full of Pentamerus oblongus and P. Icevis, considered by Mr. Conrad to be one species. On account of the occurrence of this shell, the whole of these strata have been separated from the Niagara series. 5. Ontario group.— About half a mile below the Falls the upper- most beds of the Ontario group crop out. At the whirlpool they have a thickness of 70 feet, and at Queenstown of 200, but to the latter dimension must be added 150 feet of inferior beds, exposed between Queenstown and Lake Ontario. The entire group con- sists of 1 . Red marl with beds of hard sandstone in its "| „„ , , upper division *} of the Falls of Niagara. 551 2. White quartzose strata, so hard as to form~| at Queenstown a ledge projecting beyond > 25 feet the face of the escarpment J 3. Red marl and sandstone 250 ... Other divisions of the group, concealed beneath the waters of the lake, may be studied in the cliffs of its eastern and north-eastern shores. Mr. Lyell next proceeds to give a brief account of the geographical distribution of the formations or groups. The strike of the beds be- ing east and west, and the dip very slight towards the south, the sections exposed along the Niagara afford a key to the structure of a large portion of the State of New York, the same deposits having been traced eastward through a region 40 miles in breadth by 150 in length, and westward to a much greater distance. The Helder- berg and the Niagara limestones constitute platforms which ter- minate in parallel escarpments, from twenty to twenty-five miles apart, about sixteen miles of the intervening space being occupied by the saliferous group. The Helderberg escarpment, to the east of Buffalo, is 50 feet high ; but in the neighbourhood of the Nia- gara it has been denuded and is half buried beneath drift ; it is how- ever resumed in Upper Canada, and eastward it may be followed to the river Hudson. The Niagara limestone escarpment presents at Lewistown and Queenstown a cliff 300 feet high, which may be traced eastward nearly 100 miles and westward for a much greater distance. The limestone series, however, constitutes only the up- permost third of the escarpment, the remainder being composed of the Protean and the Ontario groups ; the whole section being as fol- lows : — 1 . Niagara limestone, lower beds 30 feet. 2. Niagara, or Rochester shale 80 ... 3. Protean beds 30 ... 4. Ontario group : red marl, with hard beds in! 7ft the upper part J 5. : quartzose grey sandstone,! 9_ with Lingular, &c J 6 : red marl 100 ... 335 feet. Though only the lower beds of the Niagara limestone occur in the escarpment at Lewistown, yet, in consequence of the gentle rise of the strata to the north, the summit of these lower beds is at a higher level than that of Lake Erie. The whole of the Niagara platform is covered irregularly with hillocks of drift, beneath which the lime- stone is polished and furrowed. From the foot of the Queenstown escarpment to Lake Ontario, a distance of six or seven miles, is a low tract, consisting of sandstones belonging to the Ontario group, and dipping like the preceding beds slightly to the south. A section which accompanied the memoir to illustrate the pre- ceding details corresponds, the author says, in all essential particu- 552 Geological Society : Mr Lyell on the Recession lars with one previously published by Mr. Hall ; but the whole suc- cession of beds has been verified by Mr. Lyell in more than one line of section, from north to south. He is induced to believe, from a comparison of English Caradoc and Llandeilo fossils with suites of organic remains examined in America, that a series of beds which underlie the Ontario group, and termed by American geologists the Mohawk group, may be older than the lower Silurian rocks, and wanting in England. II. On the Recession of the Falls. — The following measurements, Mr. Lyell says, are of great importance in speculating on the past or future recession of the Falls. The distance from the point where the Niagara flows out of Lake Erie to the Falls is sixteen miles, thence to the limestone escarpment seven miles, and from this point to Lake Ontario about seven more. From Lake Erie to the commencement of the rapids, fifteen miles and a half, the river falls only 15 feet ; but from the top of the rapids to the great cataract the descent is 45 feet ; and the height of the Falls is 164 feet, perpendicular. From the base of the Falls to Queenstown, seven miles, the difference of level in the river is about 100 feet ; but from that place to Lake On- tario, seven miles further, it is only 3 or 4 feet. If the Falls were ever at Queenstown, they must, the author observes, have been about twice their present height, having lost a small portion of the dif- ference by the southern inclination of the strata, and rather more than 100 feet by the rise of the bed of the river. With respect to the opinion of the Queenstown escarpment being due to a fault, Mr. Lyell states, that the strata on the banks of the Niagara, both above and below Queenstown, presenting the same relative position as at Lockport or Rochester, the escarpment must be entirely due to denudation ; and he has no hesitation in attribu- ting this escarpment, as well as the Helderberg, to the action of the sea ; these great inland cliffs having far too great a range to have re- sulted from a former extension and higher altitude of Lake Ontario. The next question, whether the ravine through which the Niagara flows is to be regarded as a prolongation of the Queenstown escarp- ment and referable to the same period, or has been cut through by the river, is, the author states, of greater difficulty. From his own observations, he concludes that the ravine has been formed by the river ; but he assumes, that a shallow valley pre-existed along the line of the present defile, resembling the present one between Lake Erie and the Falls. His reasons for conceiving that the river has been the excavating agent, are, 1st, the ravine being only from 400 to 600 yards wide at the top, and from 200 to 400 at the bottom, between Queenstown and the Whirlpool ; 2ndly, the inclination of the bed of the river, 14^ feet per mile, being everywhere cut down to the regular strata ; 3rdly, the fact that the Falls are now slowly re- ceding ; 4thly, that a freshwater formation, which the author ascribes to the body of water which flowed along the original shallow valley, exists on Goat Island and half a mile lower down the river, and could not have been deposited after the Falls had receded farther back than the Whirlpool. Mr. Lyell considers that the indentation of the Falls of Niagara, 553 of about two acres on the American side of the Niagara, and not re- ferable to the action of that river, is no objection to the theory of the recession of the Falls, because he conceives that the stream flowing down it could have effected the denudation, aided by atmospheric agents ; and because a similar objection might be founded on a ra- vine on the Canada side opposite the Whirlpool, where several par- allel gullies have been deeply eaten into by streams. The charac- ters of this ravine were carefully examined by Mr. Lyell and Mr. Hall, and appear to have escaped previous observers. What was anciently a ravine joins the defile of the Niagara at this point, but it is entirely filled with horizontal beds of drifted pebbles, sand and loam ; the first, near the bottom of the deposit, having been cemented into a conglomerate by carbonate of lime. This is the only interrup- tion of the regular strata along the course of the Niagara ; and Mr. Lyell observes, it is desirable to ascertain if it be a prolongation of the ravine which intersects the great escarpment at St. David's, west of Lewistown. The author states, that he is by no means desirous of attaching importance to the precise numerical "calculations which have been made respecting the number of yards that the Falls have receded during the last half century, as there are no data on which accurate measurements could be made ; and because fifty years ago the district was a wilderness. Mr. Ingrahaw of Boston has, however, called his attention to a work published by the French Missionary, Father Hen- nipen, in which a view is given of the Falls as they appeared in 1678. Goat Island is represented dividing the waters as at present ; but besides the two existing cascades, a third is depicted on the Canada side, crossing the Horse- shoe Fall at right angles, and appears to have been produced by a projection of the Table Rock. In the de- scription Father Hennipen states, that this smaller cascade fell from west to east, and not like the other two, from south to north. Seventy- three years afterwards, in 1751, a letter on the Falls, by Kalm, the Swedish botanist, was published in the * Gentleman's Ma- gazine.' It is illustrated by a plate, in which the third Fall is omit* ted ; but the writer states in a note, that at that point the water was formerly forced out of its direct course by a projecting rock, and turned obliquely across the other Fall *. Mr. Lyell then proceeds to show what are the geological evidences of the former prolongation of the river's bed, on a level with the top of the ravine through which the Niagara now flows. The existence on Goat Island of strata of marl, gravel and sand, containing fossil freshwater shells, was known before Mr. Bakewell's paper on the Falls was published, and they have been more recently described by Mr. Hall f ; and Mr. Lyell states, that he was very desirous of ascertaining how far they extend on the banks of the river, or * The author has observed distinct signs of recession in strata of the Silurian and Devonian epochs at the Falls of the Genessee in Rochester and at Portage, at the Fall of Allen's Creek below Le Roy, near the town of Batavia, and at the Falls of Jacock's river, three miles north of Genessee, t Report for 1838. 554< Geological Society : Mr. D. Sharpe on the whether they could be detected below the present Falls. On the south-west side, in a cliff 12 feet in perpendicular height, a bed of gravel, 7 feet from the surface, contains eight species of fluviatile and one of terrestrial shells, determined for the author by Dr. Gould of Boston, the whole of the former now living in the wa- ters of the Niagara, and some of them even in the rapids. At the south-west extremity of Goat Island this deposit must be 24 feet thick, and it rests on the Niagara limestone. On the right bank of the river, opposite the island, are two river-terraces, one 12 feet above the stream, and the other 12 feet higher; and both have been cut out of this freshwater formation. In making a mill-dam some years ago, the same species of shells as those on Goat Island were thrown out, and Mr. Lyell had still an opportunity of col- lecting them. He was also shown a tooth of the "Mastodon Ameri- canus," which, with another tooth and a bone of the same animal, were discovered in the deposit 13 feet from the surface. From in- formation given to the author by Mr. Hooker, the guide, the forma- tion was found half a mile farther down the river, at the summit of the lofty precipice, 6 feet deep and composed chiefly of gravel. It contained in abundance Cyclas rhomboidea, Valvata tricarinata and Planorbis parvus. This patch of gravel demonstrates, therefore, the former position of the river at a level corresponding to that of the present summit of the cataract, and half a mile below the existing Falls. It proves however, Mr. Lyell says, much more ; for in order that such a fluviatile deposit should have been accumulated in water tranquil enough to allow those shells to exist, there must have been a barrier farther down ; and he is of opinion it may be safely placed as low as the Whirlpool, or three miles from the present Falls. If this be admitted, then, the author says, " we may be prepared to concede that the still narrower ravine beyond the Whirlpool was excavated by the river cutting back its course." A similar terrace, consisting of the Goat Island deposit, is di- stinctly seen also on the Canada side, and at about the same level between the Falls and the Whirlpool ; but its extent, height and fossil contents have not been investigated. If, Mr. Lyell observes, the river continue to intersect its way back, the sediment now depositing in its bed, above the Falls, will be laid dry in places, and cut into in the same manner as the Goat Island deposit. Assuming that the cataract was once at the Queenstown escarp- ment, allowance must be made, in speculating on the probable time which has elapsed in cutting the ravine, for a very different rate of retrocession at different periods, dependent on the changes in the formation intersected, especially of those which successively constituted the base of the precipice. At Queenstown and Lewis- town the fundamental rock, at the period when the Falls were there, was a soft red marl, and the river acted upon the same deposit for about three miles, where the rise in the channel, combined with the dip of the strata, caused the superincumbent hard quartzose beds, 23 feet thick, to form the base of the precipice. From this point the Geology of the South of Westmoreland. 555 retrocession must have proceeded much more slowly for about a mile, or to the Whirlpool, where a small fall of 6 or 8 feet still marks the place of the highest beds of the sandstone. After, Mr. Lyell says, the cataract had remained nearly stationary for ages at this point, it next receded more rapidly for two miles, having soft red marl 70 feet thick to erode its way through ; but beds of greater solidity, con- sisting of grey and mottled sandstone and Protean limestone, amount- ing in all to 30 or 40 feet, then offered a greater resistance, and con- tinued to retard the backward movements of the Falls, the Protean limestone occurring at the base of the present precipice. Lastly, the author offers some observations respecting the future retrocession of the Falls, quoting the opinions entertained by Mr. J. Hall (Report for 1838) on the effects which the strata above the existing cataract will have on the progress of the river, and pointing out results similar to those given by Mr. De la Beche in his ' Manual of Geology.' But all predictions, Mr. Lyell says, regarding the future history of the Falls may be falsified by the disturbing agency of man. Already a small portion of the waters of Lake Erie is carried off to supply the Welland canal, and another canal on the American side of Niagara ; and numerous mill-races have been projected and others will be required along both sides of the river, as the population and wealth of the country increase. Many cities also, situated to the eastward of the great escarpment and at a lower level, may in after times borrow water from Lake Erie, especially as the continued felling of the forests causes streams which were formerly constant to become dry in summer; and it must not be forgotten that Lake Michigan has lately been made by a cutting to feed the Illinois river, and that whatever quantity of water is abstracted from the upper lakes is taken away from the Niagara. Feb. 2nd, — " Sketch of the Geology of the South of Westmore- land." By Daniel Sharpe, Esq., F.G.S. The object of this communication, the author says, is to describe the Silurian rocks and the old red sandstone of the south of West- moreland, to define approximative^ their geographical boundaries, and to compare their lithological structure and stratigraphical phe- nomena with the equivalent formations previously noticed in other parts of the kingdom. The author, in alluding to the published labours of those who preceded him in the same district, mentions the memoir of Mr. J. Phillips on a group of slate rocks between the Lune and Wharf, Prof. Sedgwick's on the Cumbrian mountains f, Mr. J. G. Mar- shall's on a section between the Shap granite and Casterton Fell J, and Prof. Sedgwick's Geological Map of Westmoreland ; also the abstract of his memoirs on the English stratified rocks inferior to the old red sandstone §. • Geol. Trans., 2nd Series, vol. hi. part i. p. 1, 1829. t Ibid, vol. iv. part i. p. 47, 1835. % Proceedings of British Association for 1839. § Proceedings, vol. ii. p. 675 [Phil. Mag. S. 3. vol. xiii. p. 299.] ; Athe- naeum, No. 736; Proceedings, vol. hi. p. 541. 556 Geological Society : Mr. D. Sharpe on the The different formations are described under the heads of,— 1 . Coniston Limestone ; 2. Blue Flagstone Rock; 3. Windermere Rocks ; 4. Ludlow Rocks ; and 5. Old Red Sandstone. 1. Coniston Limestone. — This calcareous band, which has been laid down in great detail by Prof. Sedgwick, was adopted by Mr. Sharpe as the base of his inquiries. It usually rests upon dark brown shale, and consists, in its lowest part, of a hard, dark blue, slaty limestone, from fifty to sixty feet thick at Low Wood ; and in the upper, of thin beds of dark brown shale, alternating with others of blue limestone, which gradually diminish in thickness, and totally disappear towards the top of the formation. The bottom bed of limestone contains very few organic remains, but the shales and thinner calcareous bands abound with casts. A list of fossils given by the author includes fifteen Silurian species, seven of which be- long to the lower Silurian rocks of Mr. Murchison ; and the author places the Coniston limestone and associated shales on the parallel of that division of the Silurian system, but without attempting to define its exact relative position. Mr. Marshall, on the authority of Mr. J. Sowerby, places the Coniston limestone on the parallel of the Caradoc limestone. An exact account of the strike and dip of the rock, the author says, will be found in Prof. Sedgwick's memoir, but the general bearing of the strike of the beds throughout the western part of their course is stated to be north-east, though on approaching Shap more nearly east and west ; and the ordinary dip is stated to be south-east, with an inclination rarely less than 30°, and frequently exceeding 60°. 2. Blue Flagstone Rock. — The shales of the last deposit pass up- wards into a dark blue flagstone, the strike of which is parallel to that of the Coniston limestone, and the dip is conformable. It is stated to range from the west of Coniston by the village of Torver, the head of Coniston Lake, also south of the Ambleside road to Low Wray, and thence from the east side of Windermere, by Trout Beck and Kentmere, to the neighbourhood of the Shap granite. The faults which affected the Coniston limestone series extend into this deposit. No organic remains were found by the author, but he is of opinion that their absence may be owing to the rearrangement of the constituent particles of the rock when they assumed the slaty structure. 3. Windermere Rocks. — This vast series of beds, to which Mr. Marshall applied the name of Blawith slate, succeeds conformably to the blue flagstone, and is arranged by the author into three groups, which he calls the lowest, middle, and upper divisions. A line drawn from Coniston Water Head to Lindale, a distance of twelve miles, would cross the beds at right angles to the strike ; and though the same strata are, according to the author, frequently re- peated in a succession of parallel anticlinal ridges, yet he is of opinion that the total thickness of the formation exceeds 5000 feet. 3a. Lowest Division. — This portion of the Windermere rocks con- sists of gray schistose grits and argillaceous slates, containing thin beds of limestone on the banks of Coniston Lake. The strata are Geology of the South of Westmoreland. 557 stated to be much affected by cleavage lines. The usual strike of the beds at the foot of Coniston is said to be north-east, but great variations are shown to occur in other portions of the district, in con- sequence of anticlinal ridges which range north and south. The boundary between this division and the middle one passes from the foot of Coniston Water to the ferry on Windermere, and thence by the foot of the valley of Kentmere, across Long Sleddale at Murth- waite Crag, south of Tebay Fell, Langdale Fell and Ravenstone Fell, to Rathay Bridge, but it is much affected by dislocations. The general range of the division, Mr. Sharpe states, may be traced by the grits and slates forming a series of bold hills which stand out in relief above the tame rounded masses of the argillaceous schists of the middle division. The author alludes to a band of calcareous slates shown by Prof. Sedgwick to range from Blawith to the south-west, but he states that he failed to find its eastern continuation ; he alludes likewise to Mr. Marshall's account of having found lower Silurian fossils in it ; and he is induced, on this account, to conceive that the calcareous band may form the uppermost portion of the lower Silurian rocks. The lowest division of the Windermere series is stated to be well exposed on the shores of Coniston Lake. 3b. Middle Division. — This deposit consists of hard argillaceous rocks, usually striped or banded gray, blue, or white, and sometimes brown ; it contains also beds of soft shale and hard grits similar to those of the lowest division. On the west side of Windermere the usual strike is north-east, but to the eastward of the lake the strata are stated to be thrown into great confusion by faults ranging north and south. The boundary between this and the upper division is drawn by the author from Newby Bridge to Witherslack ; but from Whitborrow to the Lune, the southern edge of the deposit is over- laid unconformably by various rocks of more modern date. East of the Lune the Windermere rocks are stated to be less concealed by other formations, the southern boundary ranging from a little east of Barbon to Barbon Fell House, where it is again overlaid by carbo- niferous limestone. The only traces of organic remains mentioned by the author are some crushed specimens, one of which he considers to be a Phragmoceras. 3c. Upper Division. — This division consists of hard, compact, purplish greywacke, little affected by cleavage, and can be distin- guished from the Ludlow rocks only by the absence of fossils. The strata are greatly disturbed by north and south anticlinal faults. The division is exposed in only two limited districts ; one south of Windermere, and the other east of the Lune, constituting Barbon Beacon and the western end of Casterton Fell, all the intermediate district being occupied by newer formations. 4. Ludlow Rocks. — This series rests, the author says, unconform- ably on the Windermere beds ; but the want of conformity is stated to be inferred, not from the usual evidence of irregular deposition at the passage beds, but from the relative position of the two formations, the Ludlow rocks resting, in. different places, on the middle and 558 Geological Society: Mr. D. Sharpe on the upper divisions of the Windermere series. The deposit is composed of hard, purplish gray, argillaceous strata, and though intersected hy several cleavage plains, does not possess a slaty structure. The lines of stratification are usually well-marked by thin rotten layers full of casts of shells, the intermediate portions being devoid of organic remains. The range of the Ludlow rocks, as limited by the author to beds which contain fossils, and commencing west of Kendal Fell, is stated to be a narrow strip at the base of Underbarrow Scar ; and on the east of Kendal Fell, is a patch on the Tenter Fell, north-west of Kendal. In the valley of the Kent, the Ludlow rocks are con- cealed by newer deposits ; but east of the valley they constitute the high anticlinal ridge of Benson Knot and Helme, the top of the latter, however, being old red sandstone ; they occupy also all the country thence to the Lune, except the highest point of Lupton Fell, where the Windermere rocks are brought to the surface, being bounded on the west, south, and east by mountain limestone or old red sandstone. The usual strike of the beds is said by the author to be north and south, and the dip either east or west, the strike conforming to the direction of the principal faults. The chief anticlinal north and south ridges are stated to be Benson Knot, Helme, Old Hutton Common, and Lupton Fell : several east and west faults are likewise mentioned in the paper ; as in Lambrigg Park and Fell, in Mansergh Common, west of Lunesdale, and at Old Town. A gradual passage from the upper beds of the Ludlow rocks into the tilestone of the old red sandstone is exposed at the top of Helme at Old Town and the southern part of Mansergh Common ; and the author is induced to infer, from eleven of the twenty-five species found in the bottom beds of Herefordshire occurring also in the upper Ludlow rocks of that district, and from seven of the remaining fourteen species occurring low in the Ludlow rocks of Westmoreland, that the beds which have been considered to form the bottom of the old red sandstone ought to be included in the Silu- rian system. A further argument in support of this arrangement is drawn from the fact, that where the old red sandstone rests on the Windermere rocks these doubtful beds are wanting, the shells being found only where the Ludlow rock occurs. A list of thirty-four species of fossils is given in the paper, con- sisting almost solely of Ludlow Testacea figured in Mr. Murchison's work, but the author does not state positively to what portion of the Ludlow series the Westmoreland beds ought to be assigned. 5 . Old Red Sandstone. — The following distinct districts, composed of old red sandstone, occur within the area described by the author : (a.) that in the valley of the Lune and the neighbourhood of Kirkby Lonsdale ; (b.) those near Kendal and in the valleys of the Kent, Sprint, and Mint ; and (c.) that near Shap and Tebay. 5a. To the old red of the valley of the Lune, above Kirkby Lons- dale, the author assigns the bed of loose conglomerate and red clay, which he says dips under the scar limestone of Casterton, the lime- stone being inclined to the south-east at an angle of 30°, and the conglomerate to the east by north at an angle of 25°, The want of Geology of the South of Westmoreland. 559 conformity is stated to be more manifest to the westward ; for where the limestone bends round by Kirkby Lonsdale bridge it dips 25° or 30° to the south-south-east ; at Catshole quarry the strata are arched with a north-west strike ; at Hollin Hall quarry the dip is south-west 30°, and at Teamside 40° south-east ; but the old red sandstone dips throughout, as far as the beds can be seen, to the east. At Caster- ton the loose conglomerate is 100 feet thick, and passes downwards into red marl, occasionally mottled blue, and estimated to be fifty feet thick. This marl rests on alternating beds of red marl and red sand- stone, beneath which is a considerable deposit of dark red tilestone and light- coloured sandstone, forming the passage beds into the Lud- low rocks. The total thickness is estimated at 1000 feet. To the north of the Casterton fault, the lower beds of the old red sandstone arc stated to be raised up and exposed, far to the eastward of their position below Casterton ; and above this spot the right bank of the river is said to be composed of the lowest beds of the tilestones and the passage beds into the Ludlow rock, but the left bank to consist of tilestones and red sandstones. The dip is east, at an angle of 25°. Mr. Sharpe also assigns to the old red sandstone, but not definitive- ly, the bed of brown gravel, or of brown clay full of pebbles, which covers the whole of the valley of the Lune to its junction with the Rathay, and up that valley nearly to Sedbcrgh. It forms a line of low hills on each side of the Lune, resting on the northern edge of the tilestones above Barbon Beck, and conceals the junction of the Ludlow rocks on the right of the Lune with the Windermere rocks on the left of that river. 5b. Several limited patches of old red sandstone occur in the neighbourhood of Kendal, the remnants, in the author's opinion, of a once continuous mass. They consist, near Kirkby Lonsdale, of red conglomerates, red marls, and red and light-coloured sandstones, with tilestones, which pass downwards into the Ludlow rocks. Some of these patches, as on the top of Helme and at Monument Hill, two miles north-east of Kendal, have been raised to a consider- ably higher level than the rest of the formation. Three miles above Kendal the old red sandstone is well- exposed on the banks of the Sprint, consisting of Loose conglomerate 60 to 80 feet. Red marl 50 ... Thin-bedded red sandstone 30 ... The strike of the beds is north by west, and the dip east by north 10°, and they are unconformable to the adjacent older rocks. Similar beds are slightly exposed in the banks of the Mint, near Lavrock Bridge, striking east, and dipping 5° north, a bearing different from that of all the neighbouring rocks. They are separated from a more extensive patch about Greyrigg by an anticlinal ridge of the middle division of the Windermere rocks, but they cover a considerable area capped by nearly horizontal beds of mountain limestone. Around Kendal is another doubtful deposit of brown gravel, and the castle stands upon it. 5c. Shap and Tebay.— The course of the Birkbeck, from its rise 560 Geological Society : Mr. D. Sharpe on the above Shap Wells to its junction with the Lune at Tebay, intersects a deposit of old red sandstone, and the same deposit extends for some distance eastward up the valley of the Lune. It consists of the usual triple division, but the passage beds into the Ludlow rocks are entirely wanting, and the lower beds thin out in ascending the valley from Tebay. It rests on the lowest portion of the Winder- mere series. The dip is only 5° or 10° to the north-east. On the opposite side of the ridge which separates the Lune from the Low- ther, the old red again occurs in the valley of the latter river, the intervening ridge being occupied by masses of the doubtful brown gravel. Throughout this district the lowest beds of the mountain or scar limestone rest conformably on the old red sandstone. General Remarks ; or comparison of the Westmoreland strata with the equivalents in other parts of the kingdom. — The triple division of the Westmoreland old red sandstone, the author says, agrees re- markably with that of Herefordshire, as already stated by Mr. J. Phillips in his work on the Fossils of Devonshire ; the only differ- ences being the disaggregated state of the conglomerates, and the absence of the cornstones as well as of the Ichthyolites. The gradual passage from the bottom of the old red sandstone into the Ludlow rocks also coincides with the phenomena described in Herefordshire by Mr. Murchison. The Ludlow rocks of Westmoreland will also bear comparison with those of the border counties of England and Wales ; but, owing to the absence of the Aymestry limestone, it is not possible, the author states, to fix the exact relative position of the former with respect to the latter, but he says that they exactly agree with the upper division of the upper Silurian rocks of Den- bighshire, as described by the late Mr. Bowman*. With respect to the Windermere series, the author likewise hesitates to place it on an exact parallel with any of the subdivisions of the Silurian as described in Mr. Murchison's work, but he states that it precisely agrees in part with lower divisions of the Denbighshire upper Silu- rian rocks, both in general characters and the details of the com- ponent strata. The Coniston limestone Mr. Sharpe, as already stated, prefers to consider as a lower Silurian deposit, than as the equivalent of any one of the members of that series of rocks. The author then enters upon the inquiry of the principal epochs of disturbance and elevation of the Westmoreland rocks ; and he shows, 1st, that the earliest period of disturbance was connected with the outburst of the Shap granite ; inferring, from the conform- ity of the Windermere rocks with the Coniston limestone, that all these series were deposited before the outbreak of the granite ; 2nd, that the old red sandstone resting horizontally on the elevated rocks of Shap Fell, proves that this formation was accumulated after the disturbance consequent upon the protrusion of the granite; 3rd, that all the faults which affect the old red sandstone, or any newer formation, are more modern than the outburst of the granite. Although difficulties attend the fixing of the age of the Ludlow rocks relative to the outburst of the granite, on account of the complicated * Athenreum, No. 719, Aug. 7, 1841. Geology of the South of Westmoreland. 561 irregularity of the position of the former, yet the author thinks, that from the want of conformity of the Ludlow rocks to the Windermere, and from the faults which traverse them extending into the old red sandstone, that they were deposited subsequently to the protrusion of the granite. Having thus defined the limit of that event, Mr. Sharpe proceeds to show its effects. In the south of Westmoreland, he says, it threw into a high angle the strata of Coniston limestone and Windermere schists, and produced the great east and west faults around Coniston and Windermere, as well as in Middleton and Cas- terton Fells ; likewise the dislocations of the Coniston limestone, with their prolongations in the valleys of Coniston, Esthwaite, Win- dermere, Kentmere, Long Sleddale, &c, which are not continued into the Ludlow rocks. These valleys, or lines of cracks, Mr. Sharpe says, are quite distinct in character from the north and south syn- clinal valleys in those rocks ; he is also of opinion that the valley of the Lune had a similar origin, but the older rocks being con- cealed by newer deposits, its resemblance to the other valleys is less complete. Mr. Sharpe did not observe any proof of the Ludlow rocks having been disturbed anterior to the deposition of the old red sandstone, but, he says, there is abundant evidence of both those formations having been dislocated before the accumulation of the mountain limestone, as the limestone of Kendal Fell rests in a nearly horizontal position upon the upraised edges of an anticlinal ridge of Ludlow rocks, from which a covering of old red sandstone is considered to have been partially denudated : the anomalous manner in which the limestone overlies the old red sandstone of Kirkby Lonsdale is, he sa)'S, another instance. The principal north and south faults of the Ludlow rocks, and a portion of the Windermere schist, between Windermere and the Lune, are, however, considered by the author to be of later origin than the mountain limestone, and he particularly refers to the disturbances at Natlands, Farleton Knot, Hutton Roof, Lupton Fell, Witherslack, Whitbarrow and Kendal Fell. Lastly, the author calls attention to the successive elevation of hills in one direction by forces acting at different periods as a phaenomenon which has not received the thought it deserves ; and he points out as an instance the Windermere schists forming the high chain of Middle- ton and Casterton Fells, which chains, he says, were elevated from the north at the period of the eruption of the Shap granite, nearly as they are at present, for they formed, he states, the boundary of the great hollow in which the Ludlow rocks were deposited ; and the great faults which cross the Fells in an east and west direction were, he is of opinion, formed at the same period, the mountain limestone not having been broken through by the faults in which the Rathay, the Dee, and the Barbon traverse the chain : yet this chain of hills has been elevated, he adds, in the same north and south direction subsequently to the deposition of the mountain limestone, the whole band of limestone resting upon their eastern flanks having been thrown up to a high angle, and in some places much disturbed. Phil. Mag. S. a . No. 1 4 1 . SuppL Vol. 2 1 . 2 P 5G"2 INDEX to VOL. XXI. ACARI, production of, 61, 64, 312. Acids : — anisic, 16 ; anisonitric, 17 ; me- lasinic, ib. ; umbellic, ib. ; badianic, 18; cyminic, ib. ; cumino-cyminic, ib. ; uvic, ib. ; sulpho-hyposulphurous, 20 ; sulphurous,21; oxichloric, 157; stearo- phanic, 161 ; formic, 236; laurostcaric, 238 ; ferrocyanic, 325 ; hippuric, 382 ; phosphoric, 379 ; opianic, 449 ; indi- gotic, 450 ; salicylic, ib. Addison, (W.) on the mode of formation of the air-cells of the lungs, 51 . Agriculture, use of sulphate of ammonia in, 488. Air-cells of the lungs, on the mode of formation of the, 51. Aluminates, on the analysis of native, 78. American Philosophical Society, proceed- ings of the, 150. Ammonia, use of the sulphate of, in agri- culture, 488. Ammonites, on the mouths of, 546. Analytic geometry, on a theorem in, 1 76. Anatase, on the optical constants of, 277. Andesine, notice respecting, 74. Animals, minute anatomy of, 107, 168, 241. Anisic acid, 16. Antimony, presence of in arsenious acid, 238. Apjohn (Dr. J.) on the force of aqueous vapour within the range of atmospheric pressure, 389. Ashby (J. E.) on tbe use of iron wire for secondary electro-magnetic coils, 411. Atmosphere, on the transparency of the, 223. Atmospheric pressure, influence of the moon on, 227. Atomic weights, revision of the, 279, 409. Aurora borealis, remarks on, 52. Awdejew (M.) on glucinium and its compounds, 284. Baily (F.) on the mean density of the earth, 111. Balmain (W. H.) on a new process for preparing oxygen, 42 ; on compounds of boron and silicon with nitrogen and certain metals, 270. Barometrical observations, 222. Barry (Dr. M.) on fibre, 220; on the structure of muscle, 351. Bases, formula for eliminating the weights of mixed, 188. Batteries, constant, employment of ni- trate of soda for, 61. Battery, on a new form of, 311. Becquerel (E.) on the constant voltaic battery, 329 ; on the electro-chemical properties of simple bodies, and on their application to the arts, 404. Birds, on the structure of fibrinous exu- dations in, 244. Blood-corpuscles, on the nuclei of the,107. Blood, on the pus-like globules of the, 168. Bone-bed in the lower lias near Tewkes- bury, 540. Booth (J.) on the rectification and qua- drature of the spherical ellipse, 54 ; on a theorem in analytic geometry, 1 76, 444. Bowerbank (J. S.) on organic tissues in the bony structure of the Corallidae, 53. Bremicker's comet, observations on, 59. Brewing, observations on, 317. Brewster's (Sir D.) deductions from the hourly observations at Leith, remarks on, 43 ; on the absorption of light and the colours of thin plates, 208. Brodie (Rev. P. B.) on the occurrence of plants in the plastic clay, 546. Budan's criterion for the imaginary roots, on the extension of, 96. Cadmium, on some salts of, 355. Cahours (M.) on the oils of fennel, anise and star-anise, 15. Calomel, non-conversion of, into sublimate by the alkaline chlorides, 411. Calvert (F. C.) on the preparation of quina and cinchonia, 171. Cambridge Philosophical Society, pro- ceedings of the, 485. Cerium and its salts, on, 278. Chalk of the Brighton chffs, analysis of, 379. Challis (Rev. J.) on the rectilinear mo- tion of fluids, 101, 297, 423. Chemical rays, on a new class of, 453. Chemical Society, proceedings of the, 313, 378. Chemistry : — oils of fennel, anise and star-anise, 15 ; action of chromic acid on volatile oils, 17 ; action of hydrate of potassa on hydro-benzamide, 18 ; INDEX. 5G3 salts of uvic acid, 18; nicotin, 19; a new acid of sulphur, ib. ; double hypo- sulphites, 20 ; on the basic sulphate of mercury, 35 ; new process for prepa- ring oxygen, 42 ; compounds of palla- dium and platinum, 50 ; alloys of cop- per with tin and zinc, 66 ; red molyb- date of lead, 73; method of distinguish- ing between nitrates and chlorates, 74 ; sulphur in plants, 74 ; action of salts on plants, 75 ; analysis of native alu- minates, 78 ; scientific labours of Rich- ter, 81 ; hyponitrite of methyl, 150, 152; ultramarine, 156; oxichloric acid, 157 ; action of water on lead, 158 ; stearophanic acid and salts, 161 ; pal- mitine, 167 ; laurostearic acid, 1 67, 237 ; preparations of quina and cincho- nia, 171 ; general formula for elimi- nating the weights of mixed bases, 188; biniodide of mercury, 192 ; a new ox- alate of chromium and potash, 197 ; curcumine, 233 ; solubility of the in- soluble salts of the alkaline earths in chloride of sodium, 236 ; production of formic acid in oil of turpentine, ib. ; precipitation of certain salts by excess of acids, ib. ; solubility of salts in per- nitrate of mercury, 237 ; antimony in arsenious acid, 238 ; didymium, 239, 278 ; compounds of boron and silicon with nitrogen, 270; cerium and its salts, 278 ; atomic weights of chlorine arid zinc, 279 ; hyposulphites, ib. ; sulphocyanurets, 280; sulphates of alumina and chromium, 281 ; chro- mates, 283 ; glucinium and its com- pounds, 284 ; action of water on sul- phurets and haloid salts, 285 ; agency of caloric in modifying the state of aggregation of bodies, 313; decomposi- tion of oxalic methylic aether by alco- hol, 315; on brewing, 317 ; bichloride of hydrogen, 320 ; action of chlorides upon protochloride of mercury, ib. ; cinchovatina, 323 ; preparation of pure potash and soda, 324 ; detection of iodine in bromides, ib. ; ferrocyanic acid and ferridcyanideof potassium, 325, 326 ; iodide of mercury, 336 ; artificial yeast, 352 ; salts of cadmium, 355 ; analysis of the chalk of the Brighton cliffs, 379; chromate of manganese, 381 ; preparation of hippuric acid, 382; Prussian blue, 384 ; South Sea Guano, 385 ; artificial uranite, 387 ; atomic weight of elements, 409 ; conversion of calomel into sublimate, 411 ; me- thod of distinguishing zinc from man- ganese, 412 ; determination of nitro- gen, ib. ; new salt of soda and oxide of platina, 413 ; conia, 414 ; hema- toxylin, 446 ; opianic acid, 449 ; quinoiline, ib. ; iudigotic acid, 450 ; compounds of sugar with bases, 451 ; plumbo-sulphate of ammonia, 452 ; use of sulphate of ammonia in agricul- ture, 488 ; test for vegetable alkalies, 489 ; decomposition by fermentation of vegetable alkalies, 490; pepsin, 491 ; action of chlorides on mercurial compounds, 492; new mode of form- ing ammonia, 495. Chlorite, analysis of, 76. Christie (J. It.) on the extension of Bu- dan's criterion for the imaginary roots, 96. Christison (Prof.) on the action of water on lead, 158. Chromates, observations on some, 283. Chromic acid, action of, on volatile oil, 17. Chromium, on a new oxalate of, 197, 201 . Cinchonia and quina, on the preparation of, 171. Cinchovatina, a new vegetable alkali, 323. Clark (Prof.) on a new gas burner, 384. Cock (W. J.) on the production of artifi- cial uranite, 387. Colours, vegetable, on the action of the rays of the solar spectrum on, 225. Colthurst (J.) on contortions and faults produced in strata, 544. Conchyliometry, researches in, 300. Conia, on the composition of, 414. Copper, properties of the alloys of, with tin and zinc, 66. Corallidse, on organic tissues in the bony structure of, 53. Corals in a conglomerate at Malvern, 288. Cornwall, on earthquakes in, 153. Croft (H.) on a new oxalate of chromium and potash, 197 ; on some salts of cad- mium, 355 ; on the decomposition of oxalic methylic aether by alcohol, 315. Croft and Francis's notices of the inves- tigations of continental chemists, 15, 278, 446. Crombie (Ch.) on the solar eclipse of July 18, 1841, 57. Crosse (A.) on the transfer of mineral sub- stances through fluids by electric agency, 64. Crystalline reflexion and refraction, on the dynamical theory of, 228. Crystals, on the optic axes, and axes of elasticity of biaxal, 293. Curcumine, preparation of, 233. Currents produced by the induction of electric currents, observations on the, 497. Cycle of eighteen years, reviewed, 69. Daguerreotype, 426. Daniell (J. F.) on voltaic combinations, 2 P 2 564 INDEX. 54 ; on the voltaic battery, 329, 333, 421. Darwin (C.) on the effects produced by the ancient glaciers, and on the boulders transported by ice, 180. Davies (T. S.) on Pascal's mystic hexa- gram, 37 ; on the employment of po- lar coordinates in the equation of a straight line, 190. De la Rue (W.) on the agency of caloric in modifying the state of aggregation of the molecules of bodies, 3l3. De Morgan (Prof. A.) on Fcrnel's mea- sure of a degree, 22. Density, mean, of the earth, 111. Devonian system, on the position of the Cornish killas in the, 25. Dew-point, influence of the, on vegeta- bles, 1. Dialytic method of elimination, on the, 534. Didvmium, description of the new metal, 239. Dioptase, on the optical constants of, 277. Dove (Prof.), experiments in magneto- electricity, 33. Drach (S. M.) on Sir D. Brewster's de- ductions from the hourly observations at Leith, 43 ; on the aggregate mass of the binary star, 61 Cygni, 528. Draper (Dr. J. W.) on certain spectral appearances, and on the discovery of latent light, 348; on a class of chemical ravs analogous to the rays of dark heat, 453. Dufrenoy (M.) on Greenovite, 246. Earnshaw (S.) on the motion of luminous waves in an elastic medium, 46 ; on the theory of the dispersion of light, 122, 217, 340, 437. Earth, on the mean density of the, 111. Earthquakes in Cornwall, 153. Eclipse, solar, of July 18, 1841, on the, 57. Electrical Society of London, proceedings of the, 61,310, 404, 484. Electricity, experiments in, 33 ; on the transfer of mineral substances through fluids, by, 64. Electro-magnetic coils, use of iron wire for, 411. Electro-tint, remarks on, 62. Electrotype manipulation, 61. Elements, atomic weights of some, 409. Elevation and denudation of the district of the lakes of Cumberland and West- moreland, 468, Ellipse, on the rectification and quadra- ture of the spherical, 54. Eisner (M.) on the blue colour of ultra- marine, 156. Embryology, on the progress of, 337. Erdmann (M.) on haematoxylin, 446. Everest (Rev. R.), geological observations on the Himalaya mountains, 366. Ewart (P.), notice of the late, 327. Farquharson (Rev. J.) on a remarkable aurora borealis, 52. Femel's measure of a degree, remarks on, 22. Ferrocyanic acid, anhydrous preparation of, 325. Fibre, observations on, 220. Fibrine, on the structure of, 109, 171, 241. Fielding (G. H.) on the causes of the in- fluenza, 52. Fisher (Prof.) on the development of the spinal ganglia, and on malformations of the nervous system, 485. Fluid motion, remarks on, 29, 101, 297, 423. Forbes (J. D.) on the transparency of the atmosphere, and the law of extinc- tion of the solar rays in passing through it, 223. Fossil bones found on a raised beach near Plymouth, notice of, 543. Fownes (Dr. G.) on the preparation of artificial yeast, 352 ; on the prepara- tion of hippuric acid, 382 ; on South Sea guano, 385. Francis and Croft's notices of the investi- gations of continental chemists, 15, 278, 446. Francis (Dr. W.) on the fruit of Meni- spermum Cocculus, and on stearophanic acid and its salts, 161. Freezing cavern, observations on a, 358, 362. Frend (Mr.), notice of the late, 510. Fresenius (R.) on the salts of uvic acid, 1 8. Ganglia, on the development of the spinal, and on the nervous system, 485. Galloway (T.) on Femel's measure of a degree, 22. Gardner (Dr. D. P.) on the influence of the dew-point on vegetables, 1. Gassiot (J. P.) on the polarity of the vol- taic battery, 485. Geological Society, proceedings of the, 141,306,365,540. Geology : — on the position of the Cornish killas in the Devonian system, 25 ; on the stratified rocks inferior to the old red sandstone, 141 ; effects produced by the ancient glaciers of Caernarvon- shire, 180 ; on shells and corals in a conglomerate at Malvern, 288 ; on the geology of the United States, and on Stigmaria clay, 306. Geometry, analytic, on a theorem in, 176, 444. , the difficulties of elementary, &c, review of the, 405. INDEX. 565 Geometry, spherical, on the application of analysis to, 532. Gcrhardt (M.) on quinoiline, 449. Glaciers, on the effects produced by the ancient, 180 ; on some phenomena observed on, 362. Glucinium and its compounds, researches on, 284. Gold, use of the chloride of, as a test for vegetable alkalies, 489. Goodwin (H. A.) on the property of the parabola, 219. Graves (Rev. C.) on the application of analysis to spherical geometry, 532. Greenovite, description of, 246. Grove (W. R.) on the constant voltaic battery, 333 ; on a gaseous voltaic battery, 417. Guano, examination of, 385. Gulliver (G.) on the nuclei of the blood- corpuscles of the Vertebrata, 107 ; on the structure of fibrine, 109 ; on the pus-like globules of the blood, 168, 241 ; on the structure of false mem- branes, ib. Gymnotus electricus, remarks on, 62, 312. Hajmatoxylin, examination of, 446. Hall (Capt. Basil) on the occultation of Venus, Sept. 11, 1841, 58. Halley's comet, observations on, 397. Hansen (Prof.), award of the astronomi- cal gold medal to, 521. Hare (Dr.) on hyponitrite of metbyle, 150 ; on the electricity of steam, 151 ; on hypochlorite of methyle, 152. Harris (W. S.) on the action of lightning conductors, 313. Heat, specific, of plants, 1. Henderson (Prof.) on the parallax of a Centauri, 531. Herschcl (Sir J. F. W.) on the action of the rays of the solar spectrum on ve- getable colours, 225 ; on some phaeno- mena observed on glaciers, and on the internal temperature of masses of ice, 362. Hertwig (M.) on the sulphates of alumina and chromium, 281. Hess (M.) on the scientific labours of Richter, 81. Hippuric acid, on the preparation of, 382. Hood (Ch.) on changes in the structure of iron, 130. Hopkins (W.) on the elevation and de- nudation of the district of the lakes of Cumberland and Westmoreland, 468. Howard's (Luke) Cycle of 18 Years, re- viewed, 69. Hunt (Mr.) on the destruction by earth- quake of the town of Prava de Victoria, 365. Hunt (R.) on thermography, and on the formation of images in the dark, 462. Hutchinson (J.) on the specific heat and conducting power of building materials, 318. Hydrobenzamide, action of potash on, 18. Hydrogen, bichloride of, 320. Hyposulphites, on some double, 20, 279. Ice, on the boulders transported by, 180 ; on the internal temperature of large masses of, 362. Images, on the formation of, in the dark, 462. Indigo-nitric acid, experiments on, 450. Influenza, on the causes of the, 52. Institution of Civil Engineers, proceed- ings of the, 401. Iodine, detection of, in bromides, 324 ; on the coloured films formed by, upon various metals, 426. Iron, on changes in the structure of, 130. Ivory (Mr.), notice of the late, 327. Jellett (J. H.) on surfaces of the second order, 64. Kane (Dr. R.) on the compounds of pal- ladium and platinum, 50 ; on the basic sulphate of mercury, 35. Kelland (Rev. P.) on the theory of mole- cular action, 29, 124, 202, 263, 340, 342, 344, 422, 437. Klett (M.) on tachylite, 77. KobeU (M.) on chlorite and repidolite, 76. Kopp (Dr.) on some chromates, 283. Langlois (M.) on a new acid of sulphur, 19. Larocque (M.) on chloride of gold as a test for vegetable alkalies, 489. Latitude at sea, on a method of deter- mining, 531. Laurostearine and laurostearic acid, com- position of, 237. Lead, action of water on, 158. Lee's (Dr.) observatory at Hart well, on the longitude of, 56. Lee (Dr. R.) on the nervous ganglia of the uterus, 228. Lefroy (Lieut. J. H.) on the influence of the moon on the atmospheric pressure, 227. Lenz (M.) on some hyposulphites, 20. Letheby (H.) on the anatomy of the Gymnotus electricus, 312. Liebig and Wohler (Prof.) on opianic acid, 449. Light, on the theory of the dispersion of, 122, 217,340,437; on the absorp- tion of, 208. , latent, on the discovery of, 348. Lightning conductors, observations on, 63, 310, 313. Litton (Mr.) on a new salt of soda and 566 INDEX. protoxide of platina, 413 ; on the plumbo-sulphate of ammonia, 452. Littrow (Prof.), notice of the late, 510. Lloyd (Prof. H.) on a remarkable mag- netic disturbance on the 2nd and 4th July 1842, 137. Logarithmic and trigonometric tables, &c, noticed, 406. London Electrical Society, proceedings of the, 61,310, 404, 484. Luminous waves, on the motion of, in an elastic medium, 46. Lyell (C.) on the geology of the United States, and on the Stigmaria clay, 306 ; on the recession of the falls of the Niagara, 548. MacCullagh (J.) on the dynamical theory of crystalline reflexion and refraction, 228 ; on the dispersion of the optic axes, and of the axes of elasticity in biaxal crystals, 293 ; on the law of double refraction, 407. Magnetic disturbance, notice of a re- markable, 137. Magneto-electricity, experiments in, 33. Mallet (R.) on the physical properties of alloys of copper with tin and zinc, 66. Manzini (M.) on cinchovatina, 323. Marchand (M.) on indigotic acid, 450. Marianini (Prof.) on the currents pro- duced by the induction of electric cur- rents, 497. Marsson (M.) on laurostearine and lau- rostearic acid, 237. Meitzendorff (M.) on the sulphocyanu- rets, 280. Membranes, false, on the structure of, 241. Menispermum Cocculus, chemical exa- mination of the fruit of, 161. Mercurial compounds, action of chlo- rides on, 320, 492. Mercury, on the basic sulphate of, 35 ; on the change of colour in the bini- odide of, 192 ; change of colour of the iodide, 336 ; solubility of salts in per- nitrate of, 237. Meteorological observations and table, 79, 80 ; 159, 160 ; 239, 240 ; 327,328; 415, 416 ; 495, 496. Mialhe (M.) on the action of chlorides upon protochloride of mercury, 320, 492. Miller (Prof. W. H.) on the crystals of the red oxalate of chromium and pot- ash, 201 ; on the optical constants of tourmaline, dioptase, and anatase, 277. Millon (M.) on the bichloride of hydro- gen, 320. Minerals, analyses of :— chlorite and repi- dolite, 76 ; tachylite, 77 ; of native aiu- minates, 78 ; Greenovite, 246 ; on the salt steppe south of Orenburg, 357 ; on phenomena observed on glaciers, 362 ; of the Himalaya mountains, 366 ; ma- rine turtles from the London clay, 370; elevation and denudation of the Lake district, 468 ; bone-bed in the lower lias of Tewkesbury, 540 ; fossil bones on a raised beach near Plymouth, 543 ; production of faults and contortions in strata, 544 ; on plants in the plastic clay of the Hampshire coast, 546 ; on the mouths of Ammonites and on fos- sils from the Oxford clay, ib. ; reces- sion of the Falls of the Niagara, 548 ; geology of the South of Westmoreland, 555. Molecular action, on the theory of, 124, 202, 263, 340, 342, 344, 422, 437. Molecules of bodies, agency of caloric in modifying the aggregations of the, 313. Molybdate of lead, remarks on the, 73. Moon, influence of the, on atmospheric pressure, 227. Moore (Dr.) on fossil bones found on a raised beach near Plymouth, 543. Mosander (M.) on the new metal didy- mium, 278. Moseley (Rev. H.) on conchyliometrv, 300. Moser (Prof.) on latent light, 348, 409 ; on the recent discoveries of, 462. Motion, on fluid, 29 ; of luminous waves in an elastic medium, 46. M tiller (M.) observations of Halley's co- met in the years 1835, 1836, 397. Murchison (R. I.) on the salt steppe south of Orenburg, and on a remark- able freezing cavern, 357. Muscle, on the structure of, 351. Nativelle (M.) on the preparation of oxichloric acid, 157. Nervous system, on malformations of the, 485. Newmann's (F. W.) difficulties of ele- mentary geometry, reviewed, 405. Niagara, on the recession of the falls of the, 548. Nicotin, constitution of, 19. Nitrate of soda for constant batteries, 61. Nitrates and chlorates, method of distin- guishing between, 74. Nitrogen, on compounds of, with boron and silicon, 270. Nixon (C.) on the tunnels between Bris- tol and Bath on the Great Western Railway, 401. Nuclei of the blood-corpuscles of the vertebrata, observations on the, 107. O'Brien (Rev. M.) on the dispersion of light, 342, 344. Oils : — of fennel, anise, and star-anise, 15 ; action of chromic acid on volatile, 1 7 ; INDEX. 567 of turpentine, formation of formic acid in, 236. Opianic acid, preparation of, 449. Optic axes, on the dispersion of the, 293. Optical constants of tourmaline, dioptase, and anatase, 277. Ortigosa (V.) on nicotin, 19 ; on the composition of conia, 414. Otto (M.) on distinguishing zinc from manganese, 412. Owen (Prof. R.) on the fossil remains of six species of marine turtles, 370. Oxichloric acid, on the preparation of, 157. Oxygen, new process for preparing, 42. Palladium and platinum, on the com- pounds of, 50. Parabola, on a property of the, 190, 219. Parnell (E. A.) on the equilibrium of the temperature of bodies in contact,381. Pascal's mystic hexagram, 37. Pearce (J. C.) on the mouths of ammo- nites, 546. Peligot (M.) on the compounds of sugar with bases, 451. Pepsin, on the composition of, 491. Persoz (M.) on the action of chromic acid on volatile oils, 17. Phillips (J.) on shells and corals in aeon- glomerate at Malvern, 288. Phillips (Mr.) on a fatal accident by light- ning, 404. Photography, on facts connected with, 348, 409. Piesse (S.) observations on brewing, 317. Plants, on the existence of sulphur in, 74 ; action of salts on, 76 ; fossil, occurrence of in the plastic clav, 546. Plates, on the colours of thin, 208. Porrett (R.) on a curious formation of Prussian blue, 384. Posselt (M.) on the preparation of ferro- cyanic acid, 325. Potash and chromium, on a new oxalate of, 197, 201. Powell (Prof. B.) on the theory of the dispersion of light, 122, 217. Quina and cinchonia, on the preparation of, 171. Quinoiline, preparation of, 449. Rammelsberg (Dr.) on the hvposulphites, 279. Rees (J., jun.) on general formula for eliminating the weights of mixed bases, 188. Refraction, on the law of double, 407- Reizet (M.) on the determination of ni- trogen in organic analyses, 412. Repidolite, analysis of, 76. , Richter (J. B.) on the scientific labours of, 81. Roberts (M.) on a new form of battery, 311. Rochleder (M.) on the action of hydrate of potassa on hydrobenzamide, 18. Royal Astronomical Society, proceedings of the, 56, 397, 477,510; anniversary of the, 510. Royal Irish Academy, proceedings of the, 64, 228, 389, 532. Royal Society, proceedings of the, 50, 220. Rose (G.) on the molybdate of lead, 73. Rose (H.) on the analysis of native alu- minates, 78 ; on the action of water on sulphurets and haloid salts, 285. Rothman (R. W.) on the mass of Venus, 529. Salt steppe south of Orenburg, observa- tions on the, 357. Santini (M.) on Bremicker's comet, 59 ; catalogue of 1677 stars, 60. Schubert (M.) on the preparation of pure potash and soda, 324. Schulze (M.) on a new method of ascer- taining the quantity of phosphoric acid, 379. Schweitzer (Dr. E. G.) on the analysis of the chalk of the Brighton cliffs, 379. Sedgwick (Rev. A.) on the stratified rocks inferior to the old red sandstone, 141. Sharpe (D.) on the geology of the south of Westmoreland, 555. Sheepshanks (Rev. R.) on Mr. Snow's observations of Venus and the star A. S. C. 423, 398. Shells in a conglomerate at Malvern, 288. Smee (A.) on the voltaic circuit, with formulae for ascertaining its power, 248. Solar rays, on the extinction of the, 223. Specific heat and conducting power of building materials, 318. Stars, on an instrument for observing right ascensions and declinations of, 477. Steam, electricity of nascent, 151. Stearophanic acid and salts, composition of, 161. Stigmaria-clay of Pennsylvania, 306. Stokes (G. G.) on the rectilinear motion of fluids, 297, 423. Strickland (H. E.) on the occurrence of the Bristol bone-bed in the lower lias near Tewkesbury, 540. Sugar, on the compounds of, with bases, 451. Sulphocyanurets, on the, 280. Sulphur, on a new acid of, 19 ; on the ex- istence of, in plants, 74. Surfaces, on some new properties of, 64. Sylvester (Prof. J. J.) on the dialytic me- thod of elimination, 534. 568 INDEX. Tachylite, analysis of, 77. Talbot (II. F.) on the iodide of raercurv, 336. Temperature of vegetables, 1. Thibierge (M.) on chloride of gold as a test for vegetable alkalies, 489. Tithonicity, a new imponderable sub- stance, 453. Torsion-rod, experiments with the, 111. Tourmaline, on the optical constants of, 277. Tubercles, on the nature of, 171. Turpeth mineral, on the composition of, 35. Turtles, description of the fossil remains of six species of, 370. Ultramarine, on the blue colour of, 156. Uranite, on the production of artificial, 387. Uterus, on the nervous ganglia of the, 228. Uvic acid, on the salts of, 18. Vapour, aqueous, on the force of, 389. Vegetables, on the influence of the dew- point on, 1. Venus, on the lunar occultation of, Sept. 11, 1841,58; on the mass of, 398, 529. Vogel (M. jun.) on a method of distin- guishing between nitrates and chlo- rates, 74 ; on curcumine, 233 ; on pep- sin, 491. (M., sen.) on the existence of sul- phur in plants, 74 ; on the action of salts on living plants, 76. Voltaic battery, observations on the con- stant, 329 ; on a remarkable new, 417; on the polarity of the, 485. circuit, new definition of the, 248. combinations, observations on, 54. Wackenroder (II.) on the solubility of the insoluble salts of the alkaline earths in hydrochlorate of ammonia and chloride of sodium, 236 ; on the precipitation of certain salts by excess of acids, ib. Walker (C. V.) on electrotype manipula- tion, 61 ; on lightning conductors, 63, 310, 313. Wallace's (Prof.) property of the para- bola, proof of, 219. Waller (Dr. A.) on the coloured films formed by iodine, bromine, and chlo- rine upon various metals, 426. Warington (R.) on the change of colour in the biniodide of mercury, 192 ; on the red oxalate of chromium and pot- ash, 201 ; on a new chromate of man- ganese, 380. Water, action of, on lead, 158. Weppen (M.) on the production of formic acid in oil of turpentine, 236. Wettinger (M.) on an instrument for ob- serving right ascensions and declina- tions of stars, 477. Wiggers (A.) on the presence of anti- mony in arsenious acid, 238. Williams (Rev. D.) on the true position in the Devonian system of the Cornish killas, 25. Wind, effect of the direction of the, on the difference between distant baro- meters, 222. Wbhler (Prof.) on opianic acid, 449. Yeast, on the preparation of artificial, 352. Yorke (Lieut.-Col. P.) on the effect of the direction of the wind on the difference between distant barometers, 222. END OF TH VOLUME. PRINTED BY RICHARD AND JOHN E. TAYLOR, RED HON COURT, FLEET STREET. Si mr V4M ' m£:M. §3 M^- ■ ■ ^y