§ niet tatresy_ a ‘., a on abe is Grey an may -By Bat = tae eon THE LONDON, EDINBURGH, anp DUBLIN PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. CONDUCTED BY SIR DAVID BREWSTER, K.H. LL.D. F.R.S.L. & FE. &e. RICHARD TAYLOR, F.L.S. G.S. Astr. S. Nat. H. Mose. &e. SIR ROBERT KANE, M.D., F.R.S., M.R.LA. WILLIAM FRANCIS, Pu.D. F.L.S. F.R.A.S. F.C.S. JOHN TYNDALL, Pu.D. F.RB.S. &e. “Nec aranearum sane textus ideo melior quia ex se fila gignunt, nec noster vilior quia ex alienis libamus ut apes.”’ Just. Lips, Polit. lib. i. cap. 1. Not. VOL. XI.—FOURTH SERIES. JANUARY—JUNE, 1856. LONDON. TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET, Printers and Publishers to the University of London ; $OLD BY LONGMAN, BROWN, GREEN, AND LONGMANS; SIMPKIN, MARSHALL AND CO.; WHITTAKER AND CO.; AND PIPER AND CO,, LONDON: —-BY ADAM AND CHARLES BLACK, AND THOMAS CLARK, EDINBURGH; SMITH AND SON, GLASGOW ; HODGES AND SMITH, DUBLIN; AND PUTNAM, NEW YORK. “Meditationis est perscrutari occulta ; contemplationis est admirari perspicua..... Admiratio generat quistionem, questio investigationem, investigatio inventionem.”’—Hugo de S. Victore. —‘“ Cur spirent venti, cur terra dehiscat, Cur mare turgescat, pelago cur tantus amaror, Cur caput obscura Phoebus ferrugine condat, Quid toties diros cogat flagrare cometas ; Quid pariat nubes, veniant cur fulmina ceelo, Quo micet igne Iris, superos quis conciat orbes Tam vario motu.” J. B. Pinelli ad Mazonium. CONTENTS OF VOL. XI. (FOURTH SERIES.) NUMBER LXIX.—JANUARY 1855. Prof. Faraday and Dr. P. Riess on the Action of Non-conducting Boudres in Blectrie "Jaduchion 022 7iee2e ts eeu ssc ee eet ae M. R. Schneider on the pene ey of Bismuth ree Soii- = af Mr. H. C. Sorby on n Slaty Cleavage, a as 5 exhibited i in ‘the Devo- nian Dee tan GF Dera baney i. A 5A oop teas oo pin ian Mr. H. F. Baxter’s Experimental Inquiry undertaken with the view of ascertaining whether the organic actions, Lacteal Absorption and Nutrition, in the living Animal are accom- panied with the manifestation of Current Force .......... The Rev. S. Haughton on the Solar and Lunar Diurnal Tides ofthe! Coasts of Irelands. 7st to one ae Neves ets eaten os aol Mr. D. Forbes on the Effect of Chlorine in Colouring the Flame of Borning Bodies 2/752) VERY PP BF2 FIG POP OR DU 2 ee Prof. W. Thomson on the Reciprocal Action of Diamagnetic Particles SOT P2279 28 FOLANE IORI TIE OOD. Ses es Mr. A. H. Church on the Action of Water upon certain Sul- PO SEH Ong CH crcl rect ire PRCI CONIA tac ictecS OCIS ODD . Proceedings of the Royal Society... .......5:+ eseeescecees —_— Geological Society ..........0....-4. Two Processes by which the Phenomenon of Coloured Rings may be produced with great intensity, by M. Carrére...... On a new Seismometer, by M. Kreil, Director of the Imperial Meteorological Institute, Vienna ..........- esses eers Meteorological Observations for November 1855............ Meteorological Observations made by Mr. Thompson at the Garden of the Horticultural Society at Chiswick, near London; by Mr. Veall at Boston; and by the Rev. C. Clouston at Sandwick Manse, Orkney.........-+.+- sees NUMBER LXX.—FEBRUARY.- Prof. Magnus’s Hydraulic Researches. (With a Plate.).. Mr. J. Spiller’s Analysis of a Babylonian Cylinder and Amulet. Page 20 37 88 89 107 iv CONTENTS OF VOL. X1.— FOURTH SERIES. Page M. Du Bois Reymond on a Method of exhibiting fine Galvano- metric Experiments to a large audience .. ......-.....++ 109 The Rey. S. Haughton on the Solar and Lunar Diurnal Tides of the Coasts of Ireland (comtinied). >, cist: «ts-s6]t nae sane 111 Prof. Tyndall on the relation of Diamagnetic Polarity to Mag- MGCL YStAING: MEMO ete =. aye 50 fas. gan laa mie 3 Sip ied hey ce 125 M. Schonbein on Ozone and Ozonic Actions in Mushrooms .. 137 Prof. Wohler and Dr. Atkinson’s Analysis of the Meteorites of Mez6-madaras in Transylvania............02.20++2 eee 141 M. Ch. Sainte-Claire Deville on the Density of certain Sub- stances (Quartz, Corundum, Metals, &c.) after fusion and PAPIC COOL ee eno oc asin staan ale On elma nates: en 144 Proceedings Of Whe hOyal SOClety ; ii. as 70). ccm « 26) noo 146 —_——. Geological. Socigty: .« ..<} 20 Wcequneeee 163 On the cause of the Phosphorescence of the Agaric of the Olive, by WI Fabre... srnahhe we ctenes balsitl> «cht, Inet eee _ 165 On a Process of Engraving in Relief on Zinc, by J. Devincenzi. 166 Meteorological Observations for December 1855...........- 167 Oe a ee nS nO ane 168 NUMBER LXXI.—MARCH. Mr. Nicholson and Dr. Price on the Estimation of Sulphur in Iron, and on the Solubility of Sulphate of Baryta in Nitric Fru 255 SE. A ae cle ea Re 0 eae 169 Mr, E. W. Davy on some Experiments made with a view to determine the comparative Value of Peat and Peat-charcoal for Agricultural. purposes: .pily'> bj uate, +sibtannd ead aedined 172 Prof. Magnus’s Hydraulic Researches (concluded). (Witha Paes oe es os ds ws seine en ee Abe ele ie ue 178 _ Mr. R. P. Greg on the Crystalline Form of Rhodonite ...... 196 Dr. Atkinson’s Chemical Notices from Foreign Journals. ..... 197 Mr. R. W. Pearson on the Determination of Bismuth by Weight ang) WyV olumie +3 5 a resctd a: Leth. otis vid «ea heecriy. Grell ied 204 Prof. W. Thomson on the Dynamical Theory of Heat.—Part VI. Thermo-electric Cnrrentd crave oi. sinianisi siereys niles ine varie re 214 Mr. W. R. Grove’s Experiments showing the apparent Con- version of Electricity into Mechanical Force ............ 225 Proceedings of the Royal Society... ........-...00e0.s 00: 227 —_——. Geolopical eacieiy b/g cine ieGans cee-Giuboat 237 —__— Cambridge Philosophical Society 5 Seaed antec 240 On the Direction of the Vibrations of the Ether in the case of Polarized Light, by M. Haidinger ................00-- 242 On the Incandescence of Metal Wires in Alcoholic wapaus Py H. Reinsch. . Sopa sap Suse Meteorological Obsery rations for January 1856 sgl oes? \eaeia tele 247 Pe Tine vw athe Sho ail gr ew chelsea 248 CONTENTS OF VOL. XI.— FOURTH SERIES. v NUMBER LXXII.—APRIL, M. F. Reich on Diamagnetic Action ........-+00-+--2+00s 249 Mr. H. M. Witt’s Chemical Examination of certain Lakes and Springs on the Turko-Persian frontier near Mount Ararat... 257 The Rev. S. Haughton on the Solar and Lunar Diurnal Tides of the Coasts of Ireland (eontiined) LOTS LE rai: 2, 6 aie cian ch 262 Dr. Heddle on the Galactite of Haidinger, with Analyses of PICO INAUTOULCS © we oxniys asp 0 sity wpa 0 aio .0 ra Se, ela cee ise 272 Mr. A. Cayley on the Theory of Logarithms .............- 275 Prof. W. Thomson on the Dynamical Theory of Heat.—Part VI. Thermo-electric Currents (continued) ............:. 281 Mr. T. Tate on a New Double-acting Air-pump with a single CA FUG oe eerie ROSSI 1b See HRS e Esmee Reece sie 297 Notices respecting New Books :—Mr. H. Wedgwood on the Geometry of the Three First Books of Euclid, by Direct Proof, from Definitions alone, with an Introduction on the Principles PE PEE CIC HOE Saree wim ann no operon ohn gd pom nem ooh ate tee os 300 Proceedings of the Royal Society. . aaeeeieAeeeasts |) ——_— Cambridge Philosophical Society.. aang 307 Geological Society ......'....... rae oxe 311 Hiovall lastitutlon cmc sce exces sete clas 315 Contribution to the Knowledge of Fluorescence, by G. Osann.. 324 Examination of the Green Matter of Infusoria, by the Prince of SORE SEIT SGT ces 2s wpe as 0 aac tee ike sae peered as 326 Meteorological Observations for February 1s) 2 a ray. 327 SS ee IR BSR re ae ener 328 NUMBER LXXII.—MAY. Prof. Tyndall on a peculiar case of Colour Blindness ........ 329 Messrs. J. Spiller and W. Crookes’s Researches on the Methods of preserving the Sensitiveness of Collodion Plates........ 334 Sir W. Snow Harris on a General Law of Electrical Discharge. VV Ane EIGGE rd. siete la. tin eh saat Adds poertnhic weft 339 Mr. T. Tate on certain Modifications of the Form of the new Double-acting Air-pump with a Single Cylinder.......... 360 Mr. B. Williamson on the Solution of certain Differential Equa- ES aria ey eeepc 9 RE 364 Dr. Atkinson’s Chemical Notices from Foreign Journals...... 372 Mr. A. Cayley on a Result of Elimination ...... ......... 378 Prof. W. ‘Thomson on the Dynamical Theory of Heat.—Part VI. Thermo-electric Currents (continued) ........++eeseee-- 379 M. R. Clausius on the Discovery of the true form of Carnot’s BPE soo oo + > minincaing us’ 9 2) pon phy EE at i aliens 6 388 Proceedings of the Royal Society............ sseeeess sees 390 ——_————— Geological Society .... a abe steph OVO Cambridge Philosophical Society. elas sere 398 On Volknerite or Hydrotalkite, and the so-called Steatite of paaram, by C. Rammelsberg” 2... cv eete ss tee 408 vi CONTENTS OF VOL. XI.—FOURTH SERIES. Page Preparation of Peroxide of Lead by means of Ferridcyanide of Potassmm, by DrsA> Overbeck: <<. su. o:0.0- «jen sans eee 407 Meteorological Observations for March 1856 .............. 407 —————— Table... .. cece ccc cee teen eee 408 NUMBER LXXIV.—JUNE. Mr. A. Dick’s Contributions to the Metallurgy of Copper.... 409 Mr. A. Cayley on the Theory of Elliptic Motion .......... 425 The Rev. S. Haughton on the Solar and Lunar Diurnal Tides of the Coasts of Ireland (concluded) ...........- «eseoee- 428 - Prof. W. Thomson on the Dynamical Theory of Heat.—Part VI. Thermo-electric Currents (concluded) .......... 02-20% 433 Prof. W. Thomson on the Discovery of the true form of Carnot’s PI Fs(G alo) nee wee EE, a SACS ENOL. ose ks 447 Mr. W. Swan on a new Method of observing the Spectra “of BOCES «cere wineries" sh tute Pista pera a sicie it ete, 6 WEES gee ee 448 Prot..J..J; sylvester on, Projectiles! 26.05 o. 0 5 fe ns cece 450 Dr. Atkinson’s Chemical Notices from Foreign Journals,..... 453 Prof. Matteucci’s Experiments in Electro-physiology........ 461 Prof. J. J. Sylvester on an Intuitive Proof of the Existence of Twenty-seven Conics of closest Contact with a Curve of the PD Bird WeRTCe oe nator pre go: pane Gale Bete eA SPAS anon te 463 Proceedings of the Royal poeciety: Fetes... + «ans aig 464 —--— Geolopical Society > assay, asec’ arpeies 477 —o Royal: Tnsti6igian on. is © ssteete} nace «act Bes 482 On some of the principal causes of Atmospheric Electricity, by Me Brcequerel’ 47 wiz AP Si cierate oe 3 eos acta ee 484 On the Boronatrocalcite of South America, by C. Rammelsberg. 486 On a Coprolitic Deposit in Bohemia, by Prof. Reuss ........ 486 Meteorological Observations for April 1856 .............. 487 i 0 Ea AOR ant a ein EME BER 488 NUMBER LXXV.—SUPPLEMENT TO VOL. XI. Prof. Helmholtz on the Interaction of Natural Forces ...... 489 Dr. Barker on the relative value of the Ozonometers of Drs. Schénbein and Moffat, based upon daily observations for eighteen: Months at Bediord: 0005 cei: oF amiss cain: 6b sare ae 518 Dr. Riess on the Law of Electric Discharge............ ee Cie OE Mr. A. H. Church on the Production of Formic Aither...... 527 M. E. Breunlin on the Constitution of Green and Blue Ultra- finn hie eeeAteNA ey ici TERS To DEOL OCCA DO ODIRCEDOIOIS Ec ¢ 528 The Rev. J. A. Galbraith on a general Construction for finding the maximum Range of Projectiles in vacuo.............. 5388 Proceedings of the Royal Society... sof 6 acc, sleep eae 540 —_—_————_ Geological Society ..............000. 551 On some new Colouring Matters, by Arthur H. Church and Wa etl Renkin ecmrspecteters:sss.to << a78 oteveeeuupten: eevee a ame 534 1 (0S. oe Bea de Se Rati i MM ah od a une Zier a true ‘ar enenia., [si siupiedeat veda 4 Carbonate of magnes AGM: Carbonate of protoxide of iron (oxidized) 8 Peroxidized pyrites : 100:0 In this, then, the composition is that of a true dolomite, with equal equivalents of the two carbonates and no excess of car- bonate of lime. A yellow, more marly-looking specimen than the above :— Stonehouse No. 5. (Chemical analysis.) Carbonate’ of ‘lime ' 2°32... WM BD ‘ Carbonate of magnesia . . . . . 898 eee Carbonate of protoxide of iron (oxidized) 9 i Excess of carbonate of lime . . . . 10°38 100-0 Here then there is 10°8 per cent. of carbonate of lime in excess. The cause of this is often well seen in sections ; for they show that the rock has been originally an organic deposit, and that crystals of dolomite have been formed in some parts of it, and the rest has remained in its original condition. As an illustra- tion of this, I select one from Paignton, whose physical consti- tution is very similar to Plymouth No. 3 given above, with the addition of crystals of dolomite and brown-spar. Paignton No. 1. (Chemical analysis.) Tnorganie ‘clay '{..') 68 2 ORS Oke ee Gatbonate'of lime «20 9.3 Lovie Carbonate of magnesia SOO ARETE OS 1s ce aay ee Carbonate of protoxide of iron (oxidized) . ‘2 ( dolomite. Carbonate of protoxideofmanganese (oxidized) °2 Excess of carbonate of lime . . . . -. 91°5 100:0 I now give one which contains a good deal of inorganic clay, and is much reddened with peroxide of iron, seen by the micro- scope to exist as very minute grains in the solid crystals of do- lomite, and also as larger separate crystals, probably of peroxidized pyrites. as exhibited in the Devonian Limestones of Devonshire. 25 Stonehouse No. 3. (Chemical analysis.) Mucrrmntc clay) SO YR) oP NBD Warbonate iol limes Be! FARR Be Carbonate of magnesia . . 32° aoe Carbonate of protoxide of iron (oxidized) 3:2 : Perexiaized pytives™ ) PP) ) ME 7 3 L00:0 (Physical analysis.) More or less detached rhombic crystals’ 31-2 (001 to 005 inch in diameter) Indistinct crystals, &c. surrounding the 68-6 above . . Detached red crystals of _peroxidized 9 pPyebesy swew’s . 100:0 Near Ilfracombe occurs a limestone foliated with dolomitic crystals in a peculiar manner, as will be described further on ; some parts being not yet oxidized, but others converted into yellow folia by the oxidation of the protoxides of iron and manganese. Ilfracombe No. 8. (Chemical analysis.) Deere ely es S875 Sen ae HOLS RG eacbonate of lime’, (SOPs y esen eee, OARB 25°4 Carbonate of magnesia. . . 68 | dolomite Carbonate of protoxide of iron (oxidized) 3°4 ( of equal Carbonate of protoxideof manganese (oxidized) *7_} equivalents. Excess of carbonate of lime . . . . 72:0 100°0 (Physical analysis of two portions.) Rhombic crystals in bands and layers 34:5 50°8 Joints of encrinites . ..... OO 8 Oremmicelay Sess 8 I NERS 48°4, 100:0 100:0 In this the amount of crystals of dolomite or brown-spar so much exceeds what would occur if the carbonates of magnesia, iron, and manganese were combined with equal equivalents of that of lime, that I conclude that the crystals must either be more highly calcareous, or part of them pure calcareous spar. This is certainly the case in a limestone from near Plymouth (Eburton, Plymouth No. 1), consisting of alternate folia of un- altered organic clay and dark-coloured material, which, when examined by the microscope, is seen to be composed of rhombic 26 Mr. H. C. Sorby on Slaty Cleavage, crystals with portions of peroxidized brown-spar, and on chemical analysis is found to be chiefly carbonate of lime with a little magnesia and the oxides of iron and manganese. These crystals have been developed in bands, apparently along such planes of stratification as gave lines of facility for the change to occur ; and hence I should call it an organic clay, foliated along the planes of stratification with crystals of highly calcareous brown- spar. I have not yet seen any limestone, in the district under consideration, in which chemical changes have so occurred in relation to the cleavage, that it may be said to be foliated with dolomitic crystals in the true plane of cleavage, independent of stratification, in a similar manner to what has taken place with respect to some other minerals in other localities; but perhaps such might be found by a more careful examination. These physical and chemical analyses will, I trust, suffice to show the nature of the limestones under consideration, im their unaltered condition, and when metamorphosed by subsequent chemical changes. Since corals decay more readily than such tissue as that of encrinites, I conclude that the greater part of the organic clay has been derived from them, and that the De- vonian limestones were formed chiefly from the decay of corals; next to which come encrinites; whilst the proportion of other organisms is only small. The deposits have afterwards been indurated by crystallization, and the infiltration of calcareous spar; and in some cases metamorphosed by other chemical changes. Then, on elevation and exposure to the oxygen of the atmosphere, another set of changes took place, chiefly the conver- sion of pyrites, and the protoxides of iron and manganese, into higher oxides ; a process not yet completed. The actual constitution of the rocks being now described, I proceed to consider the phenomena of their slaty cleavage. In this communication I must forbear to enter into the facts on a large scale, seen in the field, for that alone would be a long subject. However, I must state that I am convinced that there is the most complete proof of rocks possessing cleavage having been so acted on by mechanical forces that they have been very considerably compressed in a direction perpendicular to the cleavage, and elongated to a certain extent in the line of the dip; as proved by the change in the thickness of the same bed when bent into contortions, and by various other facts described by Mr. Daniel Sharpe and myself (Quart. Journ. of Geol. Soe. vol. ii. p. 74, and vol. v. p. 111; Edinb. Phil. Journ. for 1853, vol. lv. p. 137). I shall therefore consider this to be an esta- blished fact, as seen on a large scale, and confine myself to showing that it has so altered the ultimate constitution of the rock as to produce the structure on which cleavage depends. as exhibited in the Devonian Limestones of Devonshire. 27 If a thin section of an organic sand be examined with the microscope, it will be seen that the fragments of coral and shell are usually much longer than broad, as if derived from sections of more or less flat portions. If the rock be very thin-bedded, for instance like the Stonesfield slate, the greater part of these lie in the plane of stratification ; but im such thick-bedded rocks as occur in the districts under consideration, when not cleaved, this is not the case, except with very large fragments. The smaller have their longer axes inclined in all positions, so that when a section cut perpendicular to the stratification is examined, there is seen to be no such arrangement as to give rise to any decided line of weakness, along which the rock would split in preference to any other. Let us now inquire what would be the effect on such a structure if the dimensions of the rock were changed by mechanical pressure. If a rock has not been compressed, we may express this by saying that the ratio of the alteration in any two directions at right angles to each other is as 1; 1; whilst if it had been com- pressed in such a manner that the proportion between lines of equal length before compression was changed so that in the line of pressure the length was one-sixth of that perpendicular to it, we may say that the ratio is as 1:6. If, for instance, before compression we had a circle, afterwards it would be an ellipse, whose axes were as 1:6, This is a very common amount of change in the line of dip in rocks that have a good cleavage, and so I take it by way of illustration. _If, then, before compression a long-shaped fragment was inclined at any given angle to the plane perpendicular to the subsequent pressure, it may be seen from general mechanical principles, as well as proved by actual experiment, that the tangent of the angle, after the change of 1; 6, would be one-sixth of the tangent of the original angle. - Thus we haye— Angles of Inclination to the plane perpendicular to the pressure. Originally. After compression. 0 0 O 10 1 41 20 3 28 30 5 30 40 7 58 50 1] 14 60 16 6 70 24 36 80 43 23 90 90 O 28 Mr. H. C. Sorby on Slaty Cleavage, According to these principles, if we suppose that in a mass of rock there were 600 particles having their longer axes lying in the space included within 5° on each side of positions inclined at 0°, 10°, 20°, &e. to the line of pressure, so that they were uni- formly distributed, as is nearly the case in thick-bedded, un- cleaved rocks, then, after compression so that the ratio was 1: 6, their distribution would be changed, as shown in the following Table :— Inclination to the direction of the Original Subsequent pressure. distribution. distribution. 0 600 100 10 600 103 20 600 113 30 600 134: 40 600 168 50 600 236 60 600 376 70 600 733 80 600 1825 90 600 3024 It will thus be seen that the effect is to produce a great dimi- nution in the quantity that are inclined in the direction of the pressure, and a great increase in those nearly perpendicular to it, and thus to cause a very great preponderance nearly in the plane perpendicular to the pressure. In fact, as will be seen, in a space of 10°, there, we have thirty-three times as many as in an equal one in the line of pressure; and if very small spaces were taken, since the ratio between the arc and tan- - gent of a very small angle is one of equality, in the exact direc- tion of the pressure, the number of particles whose axes lay in. that line would be spread over six times the space, whilst per- pendicular to it they would be condensed into one-sixth, and hence the relative amounts in those two positions would be as 12: 6?=1:386. If, then, the amount of the unsymmetrical frag- mentswas very great compared with the rest of the rock, and if their strength was such that to break them was very much more diffi- cult than to split along them without breaking them, the resist- ance to fracture in the two directions would be as 1:36; or in other words, the facility of cleavage in the plane perpendicular to the pressure would be far greater than in one inclined at any considerable angle to it. Of course for other changes of dimen- sions the same results would apply. For instance, if it was 1: 3, the relative strength would be 1 : 9, and similarly for other values. In order to confirm these results by experiment, as mentioned as exhibited in the Devonian Limestones of Devonshire. 29 in my paper in the Edinb. Phil. Journ. cited above*, I mixed scales of oxide of iron with pipe-clay, so as to have as uniform a structure as could be produced, and then compressed it, when I found that the arrangement was exactly such as that indicated by calculation. This will be better understood from an inspec- tion of the accompanying figures. Fig. 1 is a representa- tion of a portion mixed equally, then baked and rubbed to a smooth sur- face; and, like a thick- bedded, uncleaved rock, it has no decided line of weakness, due to the ar- rangement of the parti- cles; whilst fig. 2 is a drawing of a portion ori- ginally of similar struc- ture, which, having been compressed, clearly shows that it has been changed, precisely in the manner I have shown by calcula- tion to be a necessary re- sult. The dots indicate lines along which it could easily be split, without there being any fracture of the flakes; and I think no one could fail to perceive that it would be much easier to cleave it along that direction than in any other, and that a very decided line of weakness has been produced. If then an organic clay, containing fragments of coral or shell, had its dimensions changed in a similar manner, such should be their structural arrangement, and such it really is. In studying the cleavage of rocks, it is best to make sec- tions of such as have the cleavage inclined at a high angle to the stratification; for then there is no fear of confounding them together. I shall first describe the structure in the case of organic sandy clays. A very good example of this is Plymouth No. 3, of which the physical analysis is given above. In it the cleavage cuts the stratification at about 70°, and the fragments of coral, in place of lying in the plane of stratification, are chiefly inclined at low angles to the direction of the cleavage ; in pre- cisely the same manner as that shown to be the necessary result, if an uncleaved, thick-bedded rock of similar physical constitu- tion had its dimensions altered by mechanical pressure. Now, in such a case as this, it is quite out of the question to refer the * 1853, vol, ly. p. 137. 30 Mr. H. C. Sorby on Slaty Cleavage, change of structure to any crystalline action. The particles are not crystals, but are clearly proved, by their structure and form, to be fragments of organic bodies. If the cleavage was due to the mechanical cause just described, their position is most easily accounted for; but I leave the explanation of the fact, on the supposition of the instrumentality of crystalline forces, to those who advocate that view of the subject. The same is the case with the grains of quartz sand, in such limestones as contain them. For instance, in J/fracombe No. 5, of which the physical analysis is given above, and in which the cleavage is perpen- dicular to the stratification, as seen in a section cut perpendicular to the cleavage and stratification, the grains of sand are often two or three times as long as broad, and even in some cases five times; but in place of the longer axes lying in the plane of stra- tification, they are chiefly inclined at low angles to the cleavage. I may here remark that there is no difficulty in distinguishing grains of sand from small crystals of quartz, such as are met with in some cherty limestones, and that there is no doubt of them being sand in this, and that their arrangement is due to the cause I have just described. When organic clays, with or without larger fragments, have undergone consolidation, it very frequently happens that the crystallization of the granules began in various parts, and forced away the bituminous and other impurities into detached, more or less spherical spaces, which afterwards crystallized in much finer grains. On this account they now appear in sections as darker patches, giving the rock a kind of oolitic structure, though quite distinct from the more genuine oolitic grains, visible to the naked eye. These are in many cases due to crystallization taking place from certain centres, and this being therefore the reverse kind of process, I call them positive segregational oolites, whilst the others may be called negative. When the limestone has no cleavage, these negative, segregational, oolitic grains, though often of irregular form, are usually more or less equiaxed, and not very much longer in one direction than in another, and the longer axes have no particular arrangement. This is, however, very far from being the case im such as have cleavage. As ex- amples of this I may mention Plymouth No. 3, Ilfracombe No. 5, and Paignton No. 1, of which the composition has been given, and in all of which the cleavage is inclined to the stratification at ahigh angle. In them these granules, in place of being nearly equiaxed, are so compressed and elongated that they are several times longer in the line of cleavage than in the direction perpen- dicular to it; and as clearly show that there has been a change in the dimensions of the rock, affecting its ultimate constitution, as do other facts, seen on a large scale, prove it with respect to the as exhibited in the Devonian Limestones of Devonshire. 31 great mass of the beds. They indeed, on a very small scale, present us with the same phenomena as are seen in the green spots in many of the Welsh slates, as briefly described by mein the paper already referred to. In J/fracombe No. 8, whose con- stitution is given above, which is an organic clay, foliated with lenticular portions of dolomite, it is seen that the patches of erystals have been compressed and elongated in a similar manner, and hence they lie, not exactly in the plane either of stratification or cleavage, which are inclined to one another at from 10° to 20°, but in such a direction as is the resultant of their combined influence. Ina section in the plane of cleavage, the elongation in the line of dip is most clearly exhibited. In all the cases hitherto considered the organic fragments are not very numerous, and are so imbedded in an excess of organic clay, that, when the dimensions of the rock were changed, their position was altered, but they themselves did not suffer much compression. However, it is very far from being so when there was not much organic clay, or when the compression was very great ; for then they are much altered in form and structure, and sometimes to so great an extent that it was some time before I could ascertain to what kind of organism they belonged. Mr. Sharpe has shown (Quart. Journ, of Geol. Soc., vol. u. p. 74) that the larger organic bodies have had their form much altered in cleaved rocks, and I now proceed to prove that the alteration extends in some instances to the ultimate fragments, somewhat in accordance with what he supposed to occur in all slate rocks, as described in his second communication (Quart. Journ. of Geol. Soc., vol. v. p. 111), no account being taken of change of position, which, according to my own observations, is a more common cause of the cleavage. For this purpose I select the minute joints of encrinites, whose form and ultimate organic structure is so very determinate and distinct. In an uncleaved limestone, such as Hope’s Nose No. 1, of which the composition is already given, the joints of encrinites, whose diameter is on an average about z5th ofan inch, have the proportion between their breadth and length as about 3:2, though in some cases they are equal, or even as 4:5, Being thus small short cylinders, they give rise to symmetrical sections, some rectangular, and others more or less entire circles or ellipses, whose axes vary on an average from being equal to the proportion of 6:7, but when very ellip- tic 2:3, or even in rare cases as 3:5. Of all the limestones I have examined, one from Kingskers- well near Torquay, a coral-encrinitic sandy clay, possesses the most intensely developed cleavage, so much so that it required unusual precautions in preparing the thin sections; and it isa most instructive fact, that, of all I have seen, it also shows the 32 Mr. H. C. Sorby on Slaty Cleavage, greatest amount of compression. In uncleaved limestones the joints of encrinites have their longer axes either arranged pro- miscuously, or if anything they lie in the plane of stratification, but in this highly cleaved specimen they are very greatly com- pressed in the plane of cleavage. Their forms are quite distinct from those found in uncleaved limestones; they are often not symmetrical, but broken up irregularly ; and, instead of being on an average nearly equiaxed, their greatest length, which always very closely coincides with the line of cleavage, is On an average about four times that in a direction perpendicular to it ; and they show forms such as would result from the compression and distortion of the sections of the short cylinders, seen in the uncleaved specimens. But besides their form being thus changed, Fig. 3. the ultimate organic structure is altered in a 4 corresponding manner. When not compressed, the structure of an encrinite joint is as shown in fig. 8, drawn from a fragment in a Devonian limestone, magnified 200 linear. It is cellular, the cells being somewhat angular, varymg a little in size, but on the whole nearly equiaxed. This is the character when seen in a section cut perpendicular to the axes of the joints, and in many cases it is very nearly the same in every position; but in others the cells are arranged one over the other in the line of the axes of the joints, and the walls separating them in that direction are more or less absorbed, so as to give rise to a more or less irregular or perfect tubular structure. In some cases the cells are filled with dark material, whilst their walls are clear and transparent; in others they are filled with clear, crystalline calcareous spar and the walls are dark, so that the structure may be very readily seen; but when both are equally clear and transparent or uniformly dark, it cannot be recognized. In the highly cleaved limestone from Kingskerswell the struc- ture of the joints of the encrinites is very different from that just described, being usually as shownin fig. 4. This Fig. 4. has quite a different character from what is seen when the tubular structure is cut obliquely ; and besides, in uncleaved limestones the tubes in the different detached joints do not lie allin one direction, but promiscuously, whereas in this limestone the longer axes of the cells lie in the line of the compression of the joints, and nearly always in the plane of cleavage, those that do not quite coincide with it, differmg from it only in such a manner as would result from irregular giving way, or from the compression of a tubular structure inclined to the line of cleavage. On an average the cells have their as exhibited tn the Devonian Limestones of Devonshire. 33 axes at least as 1:4, and are just of such a character as would occur from the compression of the jomts to the extent which the alteration of their own form indicates. I could de- scribe similar facts with respect to other organic bodies, but these appear to me so very clear and decisive that I think it unnecessary. In most cleaved limestones this compression of the solid organic fragments is only slight, and merely their posi- tion is altered; apparently on account of the materials by which they are surrounded having given way more readily than their own tissue; but yet it may be clearly seen that, other circum- stances being the same, the amount of their compression is in proportion to the perfection of the cleavage. Not only are the organic fragments thus compressed, but also crystals of calcareous spar and dolomite. In uncleaved lime- stones detached perfect rhombic crystals are often seen; and in some highly cleaved there are such forms as would result from the breaking up and compression of similar crystals. Moreover, in uncleaved limestones the calcareous crystals, filling the cavities in organic bodies or derived from the crystallization of organic clay, have their crystalline cleavage planes almost invariably straight; whilst in cleaved limestones they are often very con- siderably bent; and this is so particularly the case in the very highly cleaved specimen from Kingskerswell, that there is scarcely any calcareous spar that has straight cleavage planes, and much of it is so broken up and bent that it is only by comparing in- termediate examples that the true nature of the structure can be ascertained. This then clearly proves that the compressing force acted so intensely and so gradually as to change the molecular arrangement even of calcareous spar and bend it, in the same manner as we may by the hand easily bend such flexible, unelastic crystals as those of tale or lead. It may perhaps be well to state that I do not think that this indicates that the rock was softened or melted by heat, but that it changed its form like a malleable substance, by the gradual movement of the ulti- mate atoms one over the other. This compression and molecular rearrangment, combined with change of position, has been most effective in producing a line of weakness and cleavage in the finely crystallized organic clay of cleaved limestones. When a thick-bedded, uncleaved, fine- grained organic clay, such as the white lias of Radstock near Bath, is examined in a section cut per- Fig. 5. pendicular to the stratification, the struc- CEUERTe Tete’ S aR OAT P RRP A? re mae aoe ' /y Fa, ture is like fig. 5, which is magnified 200 linear. The stratification is in the line of the length of the figure, and, as will -be seen, the longer axes of the crystals are arranged promiscuously, without relation Phil, Mag, §, 4, Vol, 11. No, 69, Jan. 1856, D 34 Mr. H. C. Sorby on Slaty Cleavage, to it, and are nearly equiaxed. In some thin-bedded hmestones they have their longer axes in the line of stratification. The organic clay occurring in the most highly cleaved Fig. 6. limestone of Kingskerswell has, however, a structure pAyWy as shown in fig. 6, magnified 200 linear, where the |} crystalline granules have a very unsymmetrical cha- racter, having their axes in the plane of cleavage very much longer than perpendicular to it, as though the compression indicated by the joints of the encrinites and larger crystals had affected the smallest, consti- {fp tuting the ultimate structure of therock. I think no one could compare figs. 5 and 6 without perceiving that this compression would produce a line of weak- ness. In fig. 5 it will be seen that there is no parti- cular direction along which the rock could break with- © out fracturing the crystals; whereas in fig. 6 there is clearly one along which a fracture could extend by passing amongst them, whilst in that perpendicular to it such could not be the case without fracturing very many. Taking then all the above facts into consideration, I do not see how we can arrive at any other conclusion than that the cleaved limestones have been very considerably compressed ; and that this compression has so changed the position and form of the particles of which they are composed, that such a structural weakness has been produced in a plane perpendicular to the pressure, that they may be split along it in the manner charac- teristic of slaty cleavage. Having now described facts, which to my own mind carry complete conviction that slaty cleavage is the result of mecha- nical action, I proceed to examine what evidence there is of its being due to crystalline forces. If such were the case, there are three ways in which it might be produced. In the first place, it might be supposed that the rock was analogous to a simple, large crystal, and that the slaty cleavage was similar to ecrystal- line cleavage planes. However, I am persuaded that no one who had examined a thin section of a cleaved rock with a microscope, so as to see what the structure really is, would for one moment advocate this view of the subject ; for there is such a complete difference between them that it would in my opinion be nearly as easy to prove that stratification was the result of erystallization. If any geologist does really believe in such a cause, I can only attribute it to his supposing that cleavage planes are perfect planes ; whereas the microscope shows most clearly that this is not at all the case. Even im the most perfect slates they are merely fractures passing amongst the particles, like the dotted lines in fig. 2, so as to have surfaces, smooth and level enough to the naked eye, because the grains are so minute, but seen to be as exhibited in the Devonian Limestones of Devonshire. 35 extremely irregular when magnified sufficiently to show their real nature, and so entirely different from crystalline cleavage planes (which are straight or consist of a combination of straight lines, independent of such particles), that to compare them together and to call slaty cleavage crystalline cleavage, is in my opinion most inaccurate and inappropriate. But another way in which slaty cleavage might be due to erystallization is that there were many small crystals formed, with such a crystalline polarity that there was a general line of weakness produced in the rock; and, since this view of the sub- ject is, @ priori, not at all improbable, I shall examine the facts to be observed in cleaved limestones, to see whether or no there © is any such polarity to be found in them. The analyses given above show that various chemical changes have occurred in some of them. In many, small perfect crystals have been formed, either of calcareous spar, dolomite, or brown-spar. If then there was any tendency to crystalline polarity, we should expect that their axes would have some relation to the direction of the clea- vage; but, instead of this being the case, they are inclined pro- miscuously in all positions. For instance, in Stonehouse No. 8, in a section cut perpendicular to the cleavage of the rocks in the immediate vicinity, the rhombs of dolomite are arranged in such a promiscuous manuer that there is no line of weakness and no slaty cleavage. ‘The same is the case in Stonehouse No. 2; and, indeed, when thus crystalline on account of chemical changes, so that the mechanical structure is obliterated, there is no cleavage whatever ; and, instead of giving rise to it, we may clearly see that it has a most effective contrary action. Perhaps it may be thought that the change took place after the cleavage was pro- duced; but this is disproved by the fact, that in contiguous specimens the dolomitic crystals have been broken up, and com- pressed by the mechanical actions that, according to my view of the subject, developed the cleavage. Again, in Paignton No. 1, the crystals of dolomite and brown-spar are seen to have no rela- tion to the cleavage, and are neither fractured nor altered, and appear to me to have been produced afterwards. I never saw a cleaved limestone of which it might be said that the crystals were developed at the same time as the cleavage, so as to give rise to it; and I therefore conclude that the only relation between the crystals and the cleavage is that, when they were formed before it, they were effected by the mechanical compres- sion in the same manner as organic fragments, but that they had very little, if any other influence in producing it. If they had, we should expect to find that the greater the amount of crystalline change, the more perfect would have been the deve- lopment of the cleavage, murmnes the very reverse is the case. 2 36 Mr. H. C. Sorby on Slaty Cleavage. The best method of ascertaining whether a limestone possesses any crystalline polarity is to examine a thin section of it with a polariscope, employing a magnifying power of only a few dia- meters. If the analyser be so arranged that no light passes through it, and if a section of a crystal of calcareous spar, cut in any direction but that perpendicular to its principal axis, be placed on a stage, so constructed that it may be rotated round the beam of light, it will be seen that in two positions at right angles to each other it has no effect on the polarized light, and the field remains dark. This is when one of its two axes of no double refraction coincides with the plane of polarization of the ‘ light; but, on rotating it from these positions, its depolarizing action gradually increases, and more and more light passes through the analyser, until the axes are inclined at 45° to it, and then its intensity gradually diminishes until the other axis coim- cides with it. The hght, thus passing through the analyser, has the appearance of illuminating the crystal, so that it appears to become dark or light as it is rotated ; being white or variously coloured according to its thickness and the inclination of the section to the principal axis. If there be a simple, single crystal, these effects take place simultaneously throughout the whole surface of the section; and, in a similar manner, if there was a number of small detached crystals, all arranged on a piece of glass with their crystalline axes in the same direction, they would on rotation all appear dark and light at the same time. If, how- ever, they were arranged. promiscuously, so that their axes were not inclined more in one line than in any other, when rotated, the general effect would remain the same in every position ; whilst if there was any excess, even if small, it would easily be recognized. By placing then a section of limestone on the stage of the polariscope and rotating it, we can thus determine with very great facility whether it has any general crystalline polarity in any particular direction. In this manner it may be seen that the veins of calcareous spar, filling joint cracks in limestones, have such an excess of polarity as shows that the crystals have been formed from their sides, and that many organic fragments have a polarity related to their original form and structure; but when we examine a section of a cleaved limestone, eut perpendi- cular to the cleavage, containing crystals of calcareous spar, do- lomite, or brown-spar, it is most clearly seen that it possesses no crystalline polarity whatever, or so very little as not to be recognizable even by so delicate a test. I consider this as com- plete a disproof as could possibly be desired of the supposition that there is any relation between their slaty cleavage and ery- stalline polarity. But it may be supposed that crystalline action might cause On Current Force in Lacteal Absorption and Nutrition. 37 layers of different mineral composition to be formed in such a manner as to-produce a cleavage, without there being any cry- stalline polarity. Such an alternation along planes analogous to slaty cleavage, as well as that similar to stratification, does indeed occur to a certain extent in some rocks, so far metamorphosed as to have become foliated, as I described in a paper at the late meeting of the British Association at Glasgow, on the older rocks of the Scottish Highlands. However, when not thus metamor- phosed and foliated, unaltered cleavage is seen by the microscope to be a fracture through homogeneous rock, independent of any such alternation of layers of different mineral composition ; and therefore I conclude that this cleavage-foliation no more proves simple slaty cleavage to be the result of crystalline agencies, than does stratification-foliation indicate that they gave rise to stratification. Summing up now the general facts contained in this paper, I show that, other circumstances beimg the same, the cleavage of the limestones varies directly as the amount of mechanical com- pression to which they have been subjected; and that the effect of this is such as would necessarily change the structure of un- cleaved into that which occurs in those that are cleaved. Also, that cleaved limestones possess no crystalline polarity ; and that, in place of crystallization producing slaty cleavage, it has a con- trary tendency, and when perfect and complete obliterates it altogether. Though imorganic deposits do not present us with such decisive facts, yet I am persuaded that their slaty cleavage may be satisfactorily explained on similar principles, and that they agree, not only with what may be seen with high powers of the microscope, but with the structure of mountain masses. Can I therefore hesitate to conclude that slaty cleavage is the result of mechanical and not of crystalline forces? IV. An Experimental Inquiry undertaken with the view of ascer- taining whether the organic actions, Lacteal Absorption and Nutrition, in the living Animal are accompanied with the mani- festation of Current Force. By H. ¥. Baxrur, Esq.* area following series of experiments, an abstract of which has already appeared in the Proceedings of the Royal Society (Noy. 25, 1852), form a continuation of an inquiry in- stituted for the purpose of ascertaining whether organic actions in the living animal may not be accompanied with the manifes- tation of electrical action. Having arrived at the conclusion in a former series}, that the organic process of secretion in the * Communicated by the Author. + Phil. Trans. 1848, 1852. 388 Mr. H. F. Baxter on the manifestation of Current Force living animal was attended with the manifestation of current force, we were naturally led to suppose that the kindred actions, such as lacteal absorption and nutrition, might also be accom- panied with the manifestation of the same power: the solution of this question is the object of the present paper. To avoid unnecessary repetition, we shall refer to our second paper * for the purpose of showing the mode in which the expe- riments were conducted; in that paper also will be found the precautions necessary to be observed, and some experimental arguments for the purpose of meeting certain objections that might be raised to those experiments, and as they are applicable on the present occasion we need only refer to them. We may just add, that our object is not merely to ascertain under what circumstances an effect might be produced upon the needle of the galvanometer when the electrodes are brought into contact with different parts of the living body, but to poimt out the con- neaion between certain organic actions in the living animal and the consequent effect upon the needlet. § 1. On the manifestation of Current Force during Lacteal Absorption. Experiments. Exp. 1. Cat.—Prussie acid dropped on the nose, four hours after a meal of bread and milk, having fasted fourteen hours previous. One electrode in contact with the mucous membrane of the middle portion of the small intestine, the other in contact with the chyle flowing from the same part; the chyle positive 6°, and made to increase by making and breaking contact at the mer- curial cups. Another portion of the intestines was tried with similar results, The lacteals contained a milk-white fluid. We may just remark, that similar results were obtained when the mucous membrane and the blood flowing from the same part were formed into a circuit, as shown in our former series of experiments. * Phil. Trans. 1852. ml + The prejudices which exist in reference to electro-physiological pursuits are somewhat surprising. We remember being assailed with the following remark :—if you place one electrode in contact with the axilla, and the other in contact with the mouth, you may obtain an effect upon the needle, and consequently these results prove nothing. It may scarcely be credited that the following objections have been urged :—the ¢ime has not yet arrived for the prosecution of these inquiries; physiologists have no business to use the galvanometer ; it is necessary in these researches to use a delicate galvanometer. We should not have noticed these objections, had they not been made in influential quarters. in Lacteal Absorption and Nutrition. 39 Ezp. 2. Kitten.—Prussic acid dropped on the nose, two hours and a half after a meal of bread and milk, having fasted twelve hours previous. One electrode in contact with the mucous membrane of the duodenum, the other with the chyle from the same part; the latter positive 4°. The electrodes were cleaned and used in the same manner with a portion of the intestine lower down; chyle positive 4°; the effect made to increase by making and breaking contact. The lacteals contained a clear and transparent fluid. Exp. 3. Rabbit.—Prussic acid dropped on the eye, two hours after a meal of cabbage leaves. One electrode in contact with the mucous membrane of the small intestine, the other with a supposed lacteal vessel from the same part, and afterwards with an enlarged mesenteric gland; the latter electrode positive in both instances 5°. It was difficult in this instance to ascertain precisely the lacteal vessel. Exp. 4. Rabbit.—Four hours after death ; death from natural causes. The mucous membrane of the small intestine, and what ap- peared to be a lacteal vessel from the same part, was wounded and formed into a circuit; mucous membrane negative 4°; in- creased by making and breaking contact. The electrodes were cleaned, and the mucous membrane of a different portion of the small intestine and the surface of the mesentery were formed into a circuit; the mucous membrane still negative 4°. Fluid blood in the veins; small intestines distended with a fluid very much like gruel; the abdominal viscera very moist. A portion of the intestine was removed with its contents, and a circuit then formed between the inside and outside of the gut ; the contents negative 3°. The contents were removed by passing a stream of water through the gut; no effect occurred when the circuit was formed between the inside and outside of the intestine. Lap. 5. Rabbit.— Twelve hours after death; death from natural causes. Similar circuits were formed as in the last experiment, and with similar results. Exp. 6. Rabbit.—Prussic acid dropped on the eye, two hours after a meal of cabbage leaves ; the two previous meals consisted of oats. The mucous membrane of the small intestine, and a wounded lacteal from the same part, were formed into a circuit ; the latter positive 8°. 40 Mr. H. F. Baxter on the manifestation of Current Force Between the mucous membrane and the surface of the mesen- tery; the latter positive 5°. Between the blood flowing from a vein (mesenteric) and the chyle from a wounded lacteal vessel ; no effect. No effect ensued when a circuit was formed between the blood and the surface of the mesentery, or between the chyle from a wounded lacteal vessel and the surface of the mesentery. Chyle semi-opake. Exp. 7. In this experiment a rabbit was lalled in the same manner, but three hours after a similar meal, and under the same circumstances. As the results were identical, it will be unneces- sary to relate them. fap. 8. Cat.—Prussie acid, a smal] quantity poured into the mouth, three hours after a meal of bread and milk. Between the mucous membrane of the small intestine and a wounded lacteal vessel; the latter positive 10°. An effect oc- curred upon the needle on whatever part of the mesentery the Jatter electrode was placed, and nearly to the same amount. The lacteals contained a transparent fluid. Exp. 9. Cat.—Prussic acid dropped on the tongue, four hours after a meal of raw meat and a very small quantity of bread and milk. In this case the electrode in contact with the mucous mem- brane was negative 8° to that in contact with the chyle from a wounded lacteal vessel, or in contact with the mesentery: chyle transparent. We have not thought it necessary to relate the various circuits that were formed with the different organs or substances, together with the results in all these experiments, having already referred to similar circuits in our former paper. From these experiments, we feel ourselves justified in drawing the following inferences :— 1st. That when one electrode is in contact with the mucous surface of the intestine, and the other in contact with the chyle flowmg from the same part, an effect occurs upon the needle indicating the chyle to be positive to the contents of the intes- tine; and— 2nd. That this effect occurs during the organic process of lacteal absorption. It may be urged that these experiments prove too much: that not only do we obtain an effect upon the needle when the elec- trodes are brought into contact with the mucous surface and the chyle, but also when the mucous surface and the blood are formed into a cireuit, or even with the surface of the mesentery. This argument, however, cannot be adduced as disproving the suppo- sition that the chyle and the intestinal contents may be in op- posite electric states. We have the positive fact, that the needle in Lacteal Absorption and Nutrition. 41 indicates them to be in opposite electric states ; we cannot refer these effects to the combination of the chyle with the intestinal fluid to account for the direction of the current, and assume that the chyle is acid; it may, however, be urged that the blood is positive to the intestinal secretions, as we have already shown in our former series of experiments, and that the effects are due in these experiments to the electric condition of the blood being conducted by the mesentery. We do not deny that the effects may be partly due to these circumstances; but if they were en- tirely due to them, how is it that no effect ensued when the chyle and the blood were formed into a circuit? would not this indi- cate that they are both in the same electric state ? We do not think it necessary to brmg forward any physio- logical reasons to point out the analogy between the two organic actions, secretion and lacteal absorption, as we prefer allowing our conclusions to rest upon the eaperimental evidence we have now adduced, rather than on any @ priori argument, except for the purpose of confirming our deductions. § 2. On the manifestation of Current Force during nutrition in the Muscular and Nervous Tissues*. The researches of Matteucci establish this important fact, that when the imner and external surfaces of a muscle in a live animal are formed into a circuit, current force is produced ; and the in- ference which Matteucci draws from this fact is the following, that this current depends upon the vital action of nutrition. He also states, “ we must never forget the analogy between the mus- eular electromotor element and the Voltanian element: the zine is represented by the dises of the muscular fibre, the acid liquid by the blood, the platinum by the sarcolemma. Whatever be the conducting body with which the zine is made to communi- eate with the platinum, the current is always in the same direc- tion. . .. . The chemical actions of nutrition evolve electricity +.” Reasoning from these facts and the results we had obtained in the former series of experiments, it appeared desirable to ascer- tain what would be the effect if we applied one electrode in con- * The following experiments were performed previous to our knowledge of Du Bois Reymond’s researches. As we do not wish to enter into the dispute which has arisen between Matteucci and Du Bois Reymond, and with our present knowledge of the researches of the latter experimentalist, we are anxious that the experiments should appear as originally presented to the Royal Society. Those who wish for further information in reference to this controversy, we must refer to the original papers of these two authors, a list of which may be found in a note appended to a paper published in the Philosophical Magazine for September 1855, entitled, ‘On the Force evolved during Muscular Contraction.” + Phil, Trans. 1845, p. 301. 42 Mr. H. F, Baxter on the manifestation of Current Force tact with the muscular tissue, and the other in contact with the venous blood*. . Before we proceed with our experiments we must refer to those of Du Bois Reymond, Du Bois Reymond’s experiments confirm those of Matteucci, but the former appears to have been the first to show that similar effects were obtained when the longitudinal and transverse sections of a nerve were formed into a circuit, to those when the same parts were formed into a circuit with the muscular fibre. Ezxperimenis. Ezp. 1. Kitten.—Prusste acid dropped on the nose. The skin covering the inner part of the thigh was reflected, and the abdomen laid open; one electrode in contact with the external surface of the muscles of the thigh, the other with the blood flowing from the iliac vein ; the latter negative 3°, but the effect did not continue: the former electrode was inserted into | the substance of the muscles; no effect. The muscles at the back part of the thigh were divided; one electrode in contact with the divided, the other with the external surface ; no decisive result. : Exp. 2. Rabbit.—Prussic acid dropped on the eye. The skin and fascia were reflected from the inner and fore part of the thigh, and the rectus femoris divided transversely ; one electrode in contact with the outer, the other with the divided surface; the former positive 3°; by making and breaking contact made to increase to 5°. The abdomen was laid open, one electrode in contact with the external surface of the adductor muscles of the thigh, the other with the blood from the iliac vein; an effect appeared to be pro- duced at one time in one direction, at another time in the other. The external and divided surfaces of the muscles at the back part of the thigh were formed into a circuit, the external shghtly positive. One electrode inserted into the mass on the fore part, the other into that at the back part of the thigh ; no decisive effect. One electrode inserted into the tendon of the rectus femoris, the other in contact with its external surface; no effect. Exp. 3. Cat.—Prussic acid dropped on the tongue. One electrode in contact with the external surface of the ad- ductor muscles of the thigh, the other with the blood flowing from the iliac vein, the latter slightly posztive; the former elec- * Tt has always been a matter of some surprise to us that Matteucci has never performed this experiment; at least we have not been able to find any record of his having done so. in Lacteal Absorption and Nutrition. 43 trode was inserted into the substance of the muscle, blood still positive. The external surface of the rectus and its tendon were formed into a circuit ; no effect. The external and divided surfaces of the muscles of the shoulder were formed into a circuit; a very slight effect, which soon sub- sided ; external surface positive. Exp, 4. Rabbit.—Three hours after death ; death from natural causes. The adductor muscles of the thigh were divided transversely, and the external and divided surfaces formed into a circuit; no effect. The external and afterwards the internal surface of the same mass were formed into circuits with the blood in the iliac vein; no effect. Exp. 5. Rabbit.—Prussic acid dropped on the eye. The skin was reflected from the back part of the leg; a vein wounded and one electrode in contact with the blood, the other with the external surface of the muscles; the latter posi- tive 2°. The muscular mass at the back part of the thigh was divided transversely, and the external and divided surfaces formed into circuit ; the former slightly positive. The lumbar mass of muscles was divided transversely, and a circuit formed between the external and divided surfaces; the former positive 3°. The effect appeared somewhat greater when the electrode was placed beneath, instead of upon, the lumbar fascia. A portion of the parietal bone was removed to expose the brain, the internal jugular vein divided at the base of the skull; one electrode in contact with the blood flowing from the vein, the other inserted into the cerebral mass; the former positive 8°. The electrode remaining in the brain, the other was placed in contact with the external, and afterwards with the divided sur- face of the lumbar mass of muscles; in both instances the latter electrode was positive 5°: if placed on the skin it was still posi- tive, but not to the same extent. The spinal cord was divided, one electrode inserted into its substance, the other in contact with the lumbar mass of muscles, their external and. divided surfaces; these were positive to the former 5°. Exp. 6, Rabbit.—Prussic acid dropped on the eye. One electrode inserted into the brain, as in the last experi- ment, the other in contact with the blood flowing from the in- ternal jugular vein; the latter positive 10°. The external surface of the adductor muscles of the thigh and blood flowing from the iliac vein were formed into a circuit ; the latter slightly positive, The muscular mass was divided and the 44 Mr. H. F. Baxter on the manifestation of Current Force electrode placed in contact with its divided surface, the other in contact with the blood; the latter posztive 3°. The spinal cord was divided, one electrode inserted into it, the other in contact with the divided surface of the lumbar muscles ; the latter positive 4°. Exp. 7. Rabbit.—Death from natural causes; twelve hours after death. The external and divided surfaces of the lumbar muscles were formed into a cireuit ; the former positive 2°. One electrode inserted into the spinal cord, the other in con- tact with the lumbar muscles; the latter positive 5°. One electrode imserted into the brain, the other in contact with the lumbar muscles; the latter positive 5°. The external and divided surfaces of the muscles of the thigh were formed into a circuit ; external surface positive 2°. Matteucci* alludes to some experiments performed by MM. Pacinotti and Puccinotti, and likewise by himself, in which the electrodes were inserted one into the brain, the other into the muscles: he says, “La déviation obtenue dans la premiére immersion a été toujours dans le méme sens, c’est-A-dire, que le courant a été dirigé du cerveau aux muscles dans Pammal. T/intensité du courant est trés-variable: j’ai obtenu quelquefois 80° et méme davantage, et quelquefois 10° & 15°, et toujours dans la premiére immersion.” Exp. 8. Rabbit.—Prussic acid dropped on the eye. The external surface of the muscles of the thigh and blood flowing from a vein in the groin were formed into a circuit ; no effect. Blood flowing from the internal jugular vein and the brain ; blood positive 8°. The external surface of the adductor muscles of the thigh, and blood flowing from the iliac vein, the latter slightly positive; the muscles were divided and the electrode placed in contact with the divided surface ; blood positive 3°. One electrode inserted into the brain, the other in contact with the external surface of the skin ; the latter slightly positive : it was then placed in contact with the abdominal viscera, the other remaining in the brain; the former positive 10°. Exp. 9. Cat.—Prussic acid dropped on the tongue. The rectus femoris divided transversely, the external and di- vided surfaces were formed into a circuit; the former slightly positive. The external surface of the adductor muscles of the thigh, and blood flowing from the iliac vein; the latter slightly positive: * Traité des Phénoménes Electro-Physiologiques, p. 121. in Lacteal Absorption and Nutrition. 45 when the electrode was inserted into the muscular mass, blood positive 2°, One electrode inserted into the brain, the other in contact with the blood flowing from the internal jugular vein; the latter positive 4°: the latter electrode was inserted into the muscles of the thigh, the other remaining in the brain; the former posv- tive 3°. Some difficulty occurred in exposing the brain, and the aperture was small. The external and divided surfaces of the lumbar muscles were formed into a circuit; the external positive 2°. One electrode inserted into the spinal cord, and the other in contact with the lumbar muscles, and afterwards with the abdo- minal viscera; the latter electrode positive in both instances, but more so when in contact with the abdominal viscera. Exp. 10. Cat.—Prussic acid dropped on the tongue. In removing a portion of the skull considerable hemorrhage ensued. One electrode in contact with the blood flowing from the internal jugular vein, the other inserted into the brain; a slight effect occurred sometimes in one direction and sometimes in the other ; the electrode in contact with the brain covered with blood. The external surface of the adductor muscles of the thigh, and blood flowing from the iliac vein; no decisive result: when the electrode was inserted into the substance of the muscles, blood slightly positive. The tendon of the rectus femoris and the external, and after- wards the tendon and the divided surface, were formed into cir- cuits; no effect. Other circuits were formed in all these experiments, which we have not thought worth while to relate. From these experiments we may deduce the following infer- ences :—Ist. That when the muscular tissue and the venous blood from the same limb are formed into a circuit, the effect upon the needle indicates the blood to be positive, but slightly so; and 2nd, that when the nervous tissue and the venous blood are formed into a circuit, the blood is positive*. Other inferences, confirming the experiments of Matteucci and other Italian philosophers, may be also drawn. But do not the facts we have related confirm the inference deduced by Mat- teucci as to the origin of the muscular current? And may we not draw the same inference respecting the nervous current, viz. that during the process of nutrition in the living animal the tissues (the muscular and the nervous) and the venous blood are in opposite electric states? If the experimental evidence, however, be con- sidered as not affording such direct evidence as in the case of * We do not attempt in these experiments to inquire into the force of the current, but merely to ascertain its ewistence. 46 On Current Force in Lacteal Absorption and Nutrition. secretion, we may nevertheless adduce physiological reasons, viz. the analogy which exists between the two processes—between secretion on the one hand and nutrition on the other,—in support of our conclusions. Concluding Remarks. As these inquiries have met with a degree of opposition which we can only refer to the strong prejudices which exist in refer- ence to electro-physiclogical pursuits, since no attempt that we are aware of has been made to refute either the conclusions or the experiments by experimental evidence, we nevertheless feel compelled to reply to one or two objections which have been raised, more especially in reference to our latter experiments. It has been stated that our experiments do not confirm those of Du Bois Reymond, and that it is necessary in these researches to use a delicate galvanometer. Let us first notice the former ob- jection, as it will be a means of refuting the latter. These experiments, as we have already stated, were undertaken previous to the knowledge of Du Bois Reymond’s researches. The facts which Du Bois Reymond has elicited, and which we wish to draw attention to, are those in reference to the law of the muscular current and to that of the nervous current; the former confirming the experiments of Matteucci, the latter being those which Du Bois Reymond appears to have been the first to elucidate. Our experiments, as far as we can see, not only con- firm those of Matteucci, but also tend to confirm those of Du Bois Reymond. Our object, however, was to ascertain the origin of the current (muscular current) in Matteucci’s experi- ment; and the question is, Do not our experiments tend also to point out the origin of the nervous current in Du Bois Reymond’s experiment? And surely we may allude to one circumstance, which ought to be gratifying rather than a subject of dispute, namely, that three inquirers, working independently of each other, should ultimately arrive at results which tend to confirm and support the conclusions of each independent observer. More- over, may we not adduce this circumstance also as an argument in favour of the conclusions ? In looking over our experiments, however, we find that we have not succeeded im obtaining an effect upon the needle when the tendon and the surface of the rectus femoris muscle were formed into a circuit. Du Bois Reymond appears to consider this experiment of some importance; we, on the other hand, do not consider it in the same light. We do not deny that it may be obtained*, The question, however, is this: Has Du Bois Rey- * We are assuming that this is the point of objection raised; we have never been able to get any definite and tangible objection explicitly stated. On the Solar and Lunar Diurnal Tides of the Coasts of Ireland. 47 mond himself always been able to obtain it? Has he not been compelled to suppose that there exists a layer, which he calls the para-electronomic layer, beneath the tendon capable of counter- acting the current, which, when it does occur, soon subsides? What evidence have we of the existence of this layer beyond that of its enabling us to account for the non-appearance of the assumed current? And here, in conclusion, we cannot refrain from quoting some remarks we formerly made, and which appear to us to be applicable on the present occasion. In alluding to the possibility of effects occurring with different galvanometers, we stated, “ We do not deny, but think it highly probable, that with delicate galvanometers some effect might occur. Assuming that a slight effect were obtained, it would then become a ques- tion whether the effects were not due to the changes which occur at the electrodes, rather than at the points of nutrition or secre- tion. The physical philosopher has an undoubted right to call upon the physiologist to point out the anion and cation in his circuit, or some adequate cause for the current. The fact is, the vagueness associated with the term current has misled physiolo- gists. We are firmly convinced, that, without extreme care, a de- licate galvanometer would only lead to confusion ; there is no dif- ficulty in obtaining an effect upon the needle; if anything, we obtain more than we want: the great point is to account for it when obtained, 1. e. to show with what class of phenomena the effects may be referred*.” We may just add, that these remarks ‘were not made in reference to any particular experiments, or that we intended to decry the use of delicate galvanometers, but to show that, in the employment of delicate imstruments, greater caution would be requisite in deducing our conclusions. [With reference to the foregoing paper, we would express the opinion that the subject treated of is not to be advanced by experi- ments executed in the manner described. ‘The results appear to us to belong to a class which could be obtained without the animal body as well as within it; they may add to our knowledge of general electromotive actions, but not to our knowledge of animal elec- tricity.—Eps. ] V. On the Solar and Lunar Diurnal Tides of the Coasts of Ireland. By the Rey. Samui Haveurton, Fellow of Trinity College, Dublint. N the autumn of 1850, tidal observations were commenced at twelve stations on the coasts of Ireland, under the direc- tion of the Committee of Science of the Royal Irish Academy. * Phil. Trans. 1852, p. 286. + Results of a paper read before the Royal Irish Academy, April 24, 1854. Communicated by the Author. 48 The Rey. S. Haughton on the Salar and Lunar One of these stations, Kilrush, Co. Clare, was abandoned shortly after the commencement of the observations, in consequence of difficulties experienced in obtaining a sufficiently sheltered posi- tion for the tide-gauge; and at another station, Killibegs, Co. Donegal, the observations made were not of so complete a cha- racter as at the remaining ten stations. At the request of the Committee of Science of the Royal Irish Academy, I undertook the task of reducing and discussing the tidal observations, the reduction of the meteorological observa- tions being undertaken by the Rev. Humphrey Lloyd, whose ‘ Notes on the Meteorology of Ireland,’ deduced from those ob- servations, have been recently published by the Academy. The tidal observations made under the direction of the Aca- demy were of two distinct kinds: the first bemg the observation of all the high and low waters at each of ten stations for periods varying from sixteen to twelve months; the second being the observation of complete tides at intervals of fifteen minutes, the tides selected for this purpose being four in each lunation, two spring and two neap; these observations were made at eleven stations, and, like the former, extend over a period varying from sixteen to twelve months. These two classes of observations were made for the purpose of throwing light upon different questions connected with the laws of the tides ; the first class of observations being intended to furnish data for the separation of the effects of the sun and moon in the diurnal tide, a problem not hitherto solved by ob-* servation ; and the second class of observations being intended to illustrate the laws of the semidiurnal tide, particularly in the Irish Channel, and to decide the true mean height of the water round the coasts of Ireland. In the present communication, I shall give the results of the calculations made from the daily observations, with a view to determine the separate effects of the sun and moon upon the diurnal tide. Secrron I. Description of the Tidal Stations and of the Tide- gauge used in the observations. I. Castletownsend, Co, Cork. Lat. 51° 31! N. Long. 9° 7! W. The zero of the tide-gauge was carefully referred to the iron bolt driven vertically into the rock in which the Coast-guard signal-staff is secured. The zero was 31°91 feet below this bolt. The gauge at this station was placed in the open sea, and was held in its place by stays and guys made fast to the rock. Diurnal Tides of the Coasts of Ireland. 49 II. Caherciveen, Co. Kerry. Lat. 51° 57’! N. Long. 10° 8) W. The zero of the tide-gauge, which was erected in the N.E. angle above the bridge, was referred to a provisional bench-mark made on the corner coping-stone of the bridge. The zero was 23°51 feet below this mark. III. Kilrush, Co. Clare. Lat. 52° 38’ N. Long. 9° 26! W. The tide-gauge was placed at this station on the sea-face of the steam-boat pier, and consequently exposed to the gales from the S.W. This was the only position in which it could be placed, and unfortunately it was twice washed away by the violence of the waves. The zero was referred to the copper bolt driven vertically into one of the facing-stones of the pier, and was found to be 20°59 feet below this bolt. IV. Bunown, Co. Galway. Lat. 53° 24/ N. Long. 10° 2! W. The tide-gauge at this station was erected at the inner side of the new pier built for the accommodation of fishing-boats, and was well sheltered from the west and south-west. V. Killibegs, Co. Donegal. Lat. 54° 88' N. Long. 8° 24! W. Owing to the impossibility of erecting a tide-gauge at this station in a position which would not be left dry at low water, it was determined to dispense with the daily observations, and to make the weekly observations with two tide poles, one of which was fixed to the pier near the Coast-guard house, and the other on a rock at a short distance from the shore, the latter being used only when the base of the pier was dry at low water of spring tides. The correspondence of the figures on the two poles was carefully verified. The zero of the tide-pole was 18-00 feet below the coping- stone of the pier to which it was fastened. VI. Rathmullan, Co. Donegal. Lat. 55° 7'N. Long. 7° 32! W. The tide-gauge was erected in a sheltered situation at the inner side of the pier. Its zero was 20°20 feet below the upper surface of the corner coping-stone at the southern end of the pier. Phil. Mag. 8. 4, Vol. 11, No. 69, Jan, 1856, E 50 The Rey. 8. Haughton on the Solar and Lunar VII. Portrush, Co. Antrim. Lat. 55° 12’ N. Long. 6° 38! W. The tide-gauge was erected in an angle of the northern pier, close to the spot in which the tidal observations were made in 1842. It was referred to the copper bolt driven vertically into one of the facing-stones of the quay, and its zero was found to be 12°58 feet below this bolt. VIII. Cushendall, Co. Antrim. Lat. 55° 4’ N. Long. 6° 4! W. The tide-gauge at this station was erected on the landward side of the new pier in Red Bay. The zero of the gauge was referred to the Ordnance bench- mark on the top of the wall, at the road side, north of the tunnel, above the pier; it was found to be 34°74 feet below this mark. IX. Donaghadee, Co. Down. Lat. 54° 38’! N. Long. 5° 33’ W. The tide-gauge was erected beside the pier, close to the copper bolt driven vertically into one of the facing-stones of the quay, in a sheltered position, and with deep water at the lowest tides. The zero of the gauge was 19°80 feet below this bolt. X. Kingstown, Co. Dublin. Lat. 53°17’ N. Long. 6° 8! W. The gauge was placed in the inner angle of the new harbour, and was well sheltered from all points, particularly the north- east, from which direction large waves often enter Kingstown - harbour. Its zero was referred to the copper bolt in the coping-stone of the pier near the water-tank, and found to be 18°28 feet below this bolt. XI. Courtown, Co. Wexford. Lat. 52° 40’ N, Long. 6° 12! W. Some difficulty was found at this station in selecting a suitable position for the tide-gauge, in consequence of the harbour having become partially filled with sand and gravel forced into it by the sea. The gauge was placed beside the wooden landing-stage in the open sea, in rather an exposed position. % Its zero was found to be 17:13 feet below the copper bolt driven vertically into one of the facing-stones of the entrance to the harbour. Diurnal Tides of the Coasts of Ireland. 51 XIi. Dunmore East, Co. Waterford. Lat..52° 8'N. Long: 6° 57’ W. The tide-gauge was erected at the inner angle of the harbour in a very sheltered position. Its zero was referred to the copper bolt driven vertically into one of the facing-stones of the pier, not far from the light-house. It was found to be 17°59 feet below this bolt. The twelve tidal stations just described were established be- tween September 1850 and January 1851, and were each visited twice during the cbservations. The time was found at each station by means of a vertical gnomon, with a meridian line, the observation of which at mid- day, with the aid of a table of the equation of time furnished to each observer, gave the local time with considerable accuracy. The tide-gauge consisted of a wooden case, from 20 to 28 feet in length, placed in a vertical position and closed at the bottom, excepting a few holes, guarded by copper gauze. The bottom of the case was placed 4 or 5 feet below low-water mark, and the oscillations of the water outside were scarcely sensible within the case. To the top of the case was attached a box containing a drum, over which was passed a silk cord, terminating at one extremity in a wooden float resting on the water, and at the other extremity in a small leaden counterpoise. The motion of the water inside the case was communicated by this cord to the drum, which was connected by wheel-work of a very simple character with the index-hand of a dial, marked into sixteen feet, each divided into tenths. These dials and the annexed wheelwork were made by Mr. Dobbin, of Wicklow Street, Dublin, and worked remarkably well during the whole time of being used. In addition to the index- hand traversing the dial, two other hands were placed on a separate axle, which were pushed in opposite directions by a projection placed on the index-hand, thus registering without observation the maximum and minimum heights of the tide. To obtain this registry it was only necessary to visit the dial twice during each lunar day, either at half-flood or half-ebb ; and after a few days’ practice, no difficulty was experienced by the observers in record- ing all the high and low waters, with a very slight expenditure of time. The greatest care was taken to secure accurate determinations of the exact position of the zero marked outside the case, with reference to the Ordnance and other bench-marks, the zero of the dial being made to correspond with the zero outside. The gnomons by which the time was observed were also erected with EK 2 52 The Rev. 8. Haughton on the Solar and Lunar care; and I believe that, with good observers, the error in time would be less than one minute. To the observers themselves, who were all selected from the Coast-guards at each station, too much praise can scarcely be given for the intelligence and patient industry with which they succeeded in carrying out the rules for observation in which they were carefully instructed ;_and I believe it is not too much to assert, that, so far as the observers were concerned, it would be impossible to have an extensive series of tidal observations made with greater care and accuracy. Section Il. Method of discussing the Daily Observations. The daily observations consisted, as already mentioned, of observations of all the apparent high and low waters occurring each day. These observations of height were arranged in order of occurrence, and the diurnal tide in height at high and low water calculated from them, in the following way. : The apparent height of the tide at any moment is made up of several quantities, of which the principal are,— 1. The semidiurnal tide. 2. The diurnal tide. 3. Tides of long period depending on the change of position of the sun and moon, or the semimenstrual and semi- annual tides. 4, Elevation or depression of the water due to slow changes of barometric pressure. 5. Abrupt changes due to wind. It is possible, by the following method, to separate in the ob- served high and low waters, the part due to diurnal tide and abrupt changes due to wind, from the Ist, 3rd, and 4th quan- tities just mentioned. Let h,, ho, hg, hy, h; be five successive high or low waters; the parts of these heights due to the first four causes can be repre- sented by sines and cosines. Let A cosnd be the height due to any periodic cause, ¢ being an arc of fixed magnitude, and x a quantity increasing with the time in such a way that it is in- creased by unity in the interval between two high or low waters, z, e. in about 125 24m, From this definition we have— h,=A cos (n—2) h,=A cos (n—1)¢ h,=A cos nd h,=A cos (n+1)¢ h,=A cos (n+2)¢. Diurnal Tides of the Coasts of Ireland. 53 Taking the fourth difference, we have, after some transforma- tions, 4th diff.=h,—4h, + 6h;—4h,+h,=16A cos nd sind. The right-hand member of this equation disappears for all the terms except the diurnal tide. For, in the semidiurnal tide, the value of 1s nearly 360°, and consequently sin*i¢ is evanescent ; for the tides of long period, such as those under the third and fourth heads, ¢ is a very small angle; for example, in the semi- menstrual tide, ¢ is about 12° 37', and therefore 4th difference 16A cos n(12° 37') a quantity which is perfectly insensible. The slow changes of level due to the slow changes of atmo- spheric pressure will in like manner disappear from the 4th dif- ference of the heights at high and low water, and there remains therefore nothing to consider but the diurnal tide, and. the acci- dental changes due to sudden variations of wind; the latter cannot be eliminated by any process of calculation, as they sim- ply produce the effect of making a particular height, or two or three successive heights, differ from their true values; they are to be considered as in the same category as errors of observation ; and so far as they occur, they vitiate the observations which they affect. In the diurnal tide, on the contrary, the value of ¢ is nearly 180°, and therefore sin*}@ is nearly unity ; and there- fore the whole effect of the diurnal tide remains in the 4th dif- ference of the successive heights, or Siena ee ee cis sacl = sin*(6° 18')=0-000145, Having arranged the high and low waters for the ten stations in regular order, I employed two calculators, who were unac- quainted with each other’s name and address, to calculate the diurnal tide for the high and low waters following the moon’s southing, from equation (1). I then compared these independ- ent calculations, and whenever they differed, I repeated the calcu- lation myself, and in this manner secured the perfect accuracy of the Tables, from which the results of this paper are calculated. Notwithstanding the accuracy of observation obtained by the form of tide-gauge used by us, and the evident care of the ob- servers, there are occasional irregularities in these figures which must be attributed to the fifth cause mentioned in p. 52. And such irregularities occur principally during the stormy part of the year, and occasionally on the occurrence of isolated storms ; but, on the whole, I believe the present observations of the 54. The Rev. 8S. Haughton on the Solar and Lunar diurnal tide are the most perfect that have been ever made on so large a scale and for such a length of time. Having thus eliminated the diurnal tide from the observed heights, I constructed the diurnal tide at high and low water following the moon’s southing, by points, on paper ruled into divisions of tenths of an inch; on the scale of heights, of an inch to the foot ; and of time, of five lunar days to the inch. After joining the points, a curve was drawn in the usual way, which represented geometrically the actual results of observation. These curves were then compared with other curves constructed from theory in the following manner. ’ From whatever theory of tides we set out, whether Equilibrium theory, Laplace’s dynamical theory, or Mr. Airy’s theory of canal waves, we arrive at the result that the diurnal tide is proportional to the product of the sine and cosine of the declination of the luminary; and the most general form of diurnal tide may be deduced from this supposition, combined with the well-known fact that the tide does not accompany, but follows the southing of the luminary ; and with the hypothesis of the hydrodynamical theories, that the position of the luminary corresponding to any tide is not its actual position, but the position it had at a period preceding the period of the tide, by an interval called the age of the tide. We may therefore consider the following expression as the most general expression for the height of the diurnal tide; at least it is the expression deduced from theory with which I have compared the observed diurnal tide, D=S sin 2o cos (s—i,) ++M sin 2 cos (m—i,). . (2) In this equation,— D is the height of the diurnal tide at the high or low water following the moon’s southing, expressed in feet. r S and M are the coefficients im feet of the solar and lunar diurnal tides. o and p are the declinations of the sun and moon, at a period preceding the high and low water, by an interval to be de- termined for each luminary, and called the age of the solar and lunar diurnal tide. s and m are the hour-angles of the sun and moon west of the meridian at the time of high or low water. i, and z,, are the diurnal solitidal and lunitidal intervals, or the time which elapses between the sun’s or moon’s south- ing and the solar or lunar diurnal high water, The right-hand member of equation (2) therefore contains eight quantities, of which two only, m and s, are known directly by the observed time of apparent high and low water; the Diurnal Tides of the Coasts of Ireland. 55 remaining six, three belonging to the solar, and three to the lunar diurnal tide, are to be determined, and being found, the values of D calculated from (2) are to be compared with its values deduced from observation in the way already described. The unknown quantities of the diurnal tide are therefore,— 1st. The coefficients of solar and lunar tides. 2nd. The diurnal solitidal, and lunitidal intervals. 3rd. The ages of the solar and lunar tides. Of these quantities, one, viz. the age of the solar diurnal tide, cannot be found from observation, because the sun’s place or declination changes so slowly that it is a matter of indifference what place we assign to the sun (within a limit of some days) in estimating the amount of the solar tide. The other five quan- tities may and have been found from the observations, as I shall presently show. : The constants of equation (2) were found as follows for each of the ten tidal stations. An inspection of equation (2) shows that the solar diurnal tide disappears at the equinoxes (because a=0, or is very small), hence the equinoctial diurnal tide ob- served at high and low water is altogether due tothe moon. The lunar diurnal tide was thus found approximately from the equi- noctial tides, and was constructed on the same abscissz as the observed diurnal tide. This lunar tide, constructed from calcu- lation, differs considerably from the observed diurnal tide at the solstices, the difference being due to the solar diurnal tide. In this way the solar diurnal tide was in its turn calculated approxi- mately from the solstitial tides, and the calculated solar tide carefully superposed upon the lunar tide. The observed and calculated tides, constructed as just de- scribed, were then compared, both with reference to the maximum heights at high and low water, both positive and negative; and with reference to the times of vanishing of the diurnal tide at high and low water; and from this comparison the constants used in the construction were corrected, and the heights and times again compared, until the agreement was as close as the observations would allow. The constants thus successively corrected are those given for each locality, and the comparison of the observed and calculated tides is also given, so as to afford a very good idea of the degree of agreement between the observations and theory. The unknown constants of equation (2) are— Lunar Diurnal Tide. 1. Age of tide. 2. 7,,= lunitidal interval. 3. M= coefficient of lunar tide. 56 The Rev. 8. Haughton on the Solar and Lunar Solar Diurnal Tide. 5 Age of tide. },= solitidal interval. 6. §= coefiicient of solar tide. These constants were found as follows from the comparison of ne observed and ealeulated tides :— . The age of lunar tide was found from the comparison of Zs times of vanishing of the observed and calculated tides. 2. The lunitidal interval 2 = 7,, was found from the equation Range of lunar diurnal tide at high water : : Py, Range of lunar diurnal tide at low water 4, The lunar coefficient =M was found from the equation oe cot (m—1,,) = 2M sin 2(max. value of «) = (Range of lunar diurnal tide at high water)” (4) “+ Dak of lunar diurnal tide at low water)? 4. The age of solar tide was not determined. 5. The solitidal interval =i, was found from the comparison of the solstitial intersections of the observed diurnal tide with the calculated lunar tide. 6. The coefficient of the solar tide =S was found from the equation 28 sin 2(max. value of c) = maximum range of solar diurnal at So tatronde anil iam hina obits onic ca aene ee Srection ILI. Diurnal Tide at Castletownsend. Having constructed the observations contained in the calcu- lated tables by means of curves, as already described, I found it impossible to separate the effects of the sun and moon. The tide is so small, and its times of vanishing consequently so badly marked, that it was not possible to divide it with any kind of certainty into a solar and lunar tide. I therefore supposed the tide to be due to the moon only, and made the following infer- ences, which I do not, however, consider as of high value. The mean of all the maximum values of the tide at high water was found to be +0°0885 and —0-0835, giving an average range at high water of 0°1720 ft. The mean of all the maximum values at low water was found to be +0:0820 and —0-0906, giving an average range at low water of 0°1726 ft. If, therefore, 4 and / represent the ranges of diurnal tide at high and low water respectively, we have, by equation (2), h=2M sin (2 max. declination) cos (m—12,,) /=2M sin (2 max. declination) cos (90° + m—i,) ; - Diurnal Tides of the Coasts of Treland. 57 and consequently, by equation (3), . = — cot (m—1,,). Substituting for A and / their values, we find 01720 01726 and, converting 45° 6! into time, we have M—in=3" 6%; but m, which is the establishment at Castletownsend expressed in local time, is equal to 44 17™, and therefore Gm Lh 11, Equation (4) also gives us the relation 2M sin (2 max. declination) = / e+P. = cot (m—im) = cot (45° 6') ; Hence Vh?+1? _0:234 lager sin (42°) 0°669 ) If, therefore, the diurnal tide at Castletownsend be supposed wholly due to the moon, it may be expressed by the formula D=0'181 sin 24 cos (m—1» 11™). In this equation, 4, the moon’s declination, is to be assumed for a period preceding the time of observation. The length of this period or age of the tide could not be ascertained in conse- quence of the irregularity of the times of vanishing. It appears from the preceding investigation, that the maximum effect in raising or lowering the sea produced by the diurnal tide at Castletownsend is 0:18] ft. x sin 42°=0-117 ft. =1°4 inch, the total effect both ways being less than 3 inches. It is not surprising that it should be difficult to separate such a small effect as this into a solar and lunar tide. = 0363 feet. Section IV. Diurnal Tide at Caherciveen. In discussing the solar and lunar diurnal tides involved in the tables calculated for Caherciveen, the following results were arrived at :— I. Diurnal tide in height at high water. Maximum value of lunar tide for positive heights=0-15ft. ~ Maximum value of lunar tide for negative heights=0:20 ft. . Maximum value of solar tide =0°245 ft. . Diurnal solitidal interval =3> 28". . Age of lunar tide =5¢ 4", CU 09 58 The Rev. S. Haughton on the Solar and Lunar II. Diurnal tide in height at low water. . Maximumvalue of lunartide for positiveheights =0°230ft. . Maximum valueoflunartidefornegative heights=0'300ft. . Maximum value of solar tide =0°245 ft. . Diurnal solitidal interval =3" 28™. . Age of lunar tide =4¢174, Adding together the first two of each of the preceding series of values, we find,— Range of lunar tide at high water =h=0'350 ft. Range of lunar tide at low water =/=0°530 ft. oR WO wr Hence by equation (3), ; 0°350 cot (M—in) = F539 = 0t (56° 34") ; which, converted into time, gives M—tn =O" 54” ; but m, the moon’s hour-angle at high water in Caherciveen time, is 34 48™, and therefore dm = 0> 6™, By equation (4), we have max. value of 2M sin 2u= / (0:35)?+ (0°53)?=0-635 ft., from which we obtain M=0:480 ft. And since the maximum value of the solar tide at high water is 0°245 feet, we have, by equation (5), max. value of 28 sm 2o=0°490 ft. ; therefore S=0°335 ft. Combining together the preceding results, we have the follow- ing tidal constants for Caherciveen :— 1. Lunitidal interval =04 6™. 2. Solitidal interval =38 28", 3. Age of lunar tide =5¢ 45 at high water. do. do. =44 17 at low water. 4. M=0°480 ft. 5. S =0°335 ft. 6. Ratio of solar to lunar coefficient, S or TF =0°'698. The solar and lunar tides were constructed from the preceding constants, and compared with the observed tides. The results of this comparison are contained in the following Tables. No. BONIS OTH Co bo January 14 112 54™, No. CONN oe be Diurnal Tides of the Coasts of Ireland. Caherciveen Tide, Table A. Positive heights at high water for sixteen lunations, commencing 1850, October202174 30™, and ending1852, January 1¢11554™. 59 Observed. |Calculated. Difference. ft. 0-14 0:27 0:23 0:24 0-28 0-22 0:08 0-14 | Observed. |Calculated. ft. 0:23 0:24 0:35 0°37 0:28 0:26 017 0-14 0-19 ft. 0-16 0-20 0:24 0:29 0:27 0-21 0:08 0-13 ft —0-02 | 40:07 —0-01 0-05 40-01 40-01 0-00 40-01 Mean difference = —0'004 ft. Caherciveen Tide, Table B. Negative heights at high water for sixteen and a half lunations, commencing 1850, October 74 215 6™, and ending 1852, ft. 0-22 0:22 0-24 0°37 0:35 031 0:27 0-15 0°17 Difference. ft. 40-01 +0-02 4011 0-00 —0:07 —0-05 —0-10 —0-01 +0-02 No. Observed. ft. 10 0:34 il 0:38 12 0°36 13 0:27 14 0°25 15 0-14 16 0°28 17 0°31 Mean difference =0:000 ft. Calculated.| Difference. ft. ft. 0°34 0:00 0°37 +0°01 0-35 | +0-01 0°33 — 0:06 0-16 | +0-09 0-12 | +0-02 025 | +003 0°34 —0:03 No. Cbserved. | Calculated.) Difference. pees be Seas posed FE ft. ft. ft. 9 0-20 0719 +001 10 0:23 0-20 —0:07 1l 0-24 0°29 —0°05 12 0:20 0:26 —0°05 13 0-13 0:19 —0-:06 14 O11 | 0-09 — 0:02 15 0:18 | 0-10 +0:08 16 | 028 | O21 | +0-07 The following Tables show the comparison of the observed and calculated diurnal tide at low water at Caherciveen. Caherciveen Tide, Table C. Positive heights at low water for sixteen and a half lunations, commencing 1850, October 94 25 3™, and ending 1852, Ja- nuary 54 15> 6™, No. Canacwcrodvor~ ft. 0°27 0:40 0-44 0-41 0°35 0°27 0°28 0-40 0°42 Observed. Calculated. | Difference. ft. 0:30 0°37 0:43 0-44 0:37 0-24 0:27 0°35 0-41 ft. —0-03 +0-03 +0-01 —0:03 —0-02 40:03 +001 40:05 | +0-01 No. 10 11 12 13 14 15 16 17 ft. 0-41 0°40 0°32 0°30 0-28 0:32 0:40 0:46 { Mean difference = —0'002 ft. ft. 0°45 0-40 031 0:27 0°28 0°38 0°43 0:46 Observed. |Calculated.| Difference. ft. — 004 0:00 4001 40:03 0:00 —0-06 —0:03 0:00 60 The Rey. S. Haughton on the Solar and Lunar Caherciveen Tide, Table D. Negative heights at low water for sixteen lunations, commencing 1850, October 244 0% O™, and ending 1851, December 21¢ 15» 30”. ft. 0°36 0:55 0-51 0°37 0:43 0:36 0:38 No. | Observed. |Caleulated.| Difference.||} No. | Obseryed. |Calculated.} Difference. ft. ft. ft. ft. ite 0:40 —0°04 9 0:52 0-56 —0:04 059 | —0-04 || 10 | 063 | 060 | +003 0°55 — 0-04 11 0:45 0:46 -—0:01 0:46 —0:09 12 0:40 0°38 +0°02 0:38 +0:05 13 0:32 0:32 0-00 _ 031 +0:05 14 0:41 0:37 +0:04 0:36 +002 || 15 0:50 0:50 0:00. 0:49 0-00 16 | 0°55 0:52 +0:03 MIS Ot Se bho 0:49 Mean difference = — 0-001 ft. The four preceding Tables show the agreement in height be- tween the observed and calculated tides at Caherciveen. The following Tables show the differences of the observed and caleu- lated times of vanishing of the diurnal tide, during the sixteen and a half lunations of observation. Caherciveen Tide, Table E. Difference of observed and calculated times of vanishing at high Z ° Coe Go bo — =e COOCOnNS water, expressed in lunar days. Age of lunar tide = 54 4, | Difference.|| No. | Difference.| No. | Difference. days. | days. days. 0:00 | 12 0:00 23 0:00 —1°75 13 0:00 24 —0:50 0:00 14 0:00 25 +0°85 0:00 15 +240 || 26 — 1:25 42:00 || 16 | —3-25 || 27 | +150 —0°75 17 0:00 28 0:00 +0°25 18 —1:50 29 0:00 +0°90 19 —1:50 30 +0°50 40-75 || 20 0-00 || 31 | —1-00 - 0:00 21 —0°35 32 +1-00 +1:75 22 0:00 Mean difference = —0-002 lunar days. Diurnal Tides of the Coasts of Ireland. 61 Caherciveen Tide, Table F. Difference of observed and calculated times of vanishing at low water, expressed in lunar days. Age of lunar tide = 4¢ 17%. No. | Difference./| No. | Difference.|| No. | Difference. days, days. days. ] +0°45 12 —0:95 23 —0°55 2 —0°55 13 —1:80 | 24 —0:40 3 —015 14 +0°45 || 25 —0:15 4 | +4045 || 15 | +005 | 26 | +0-95 5 | +045 || 16 | +045 | 27 | 41-45 6 | +0-70 || 17 | +0-45 || 28 | +080 7 | +0-45 || 18 | +0-45 || 29 | 10:80 8 | 41-40 || 19 0-00 | 30 | 40-45 9 | +045 || 20 | —1:15 | 31 | 40:45 10 —2-05 21 —1:40 32 —1:05 11 | —015 || 22 | —0-40 | 33 | +0-90 Mean difference = —0:003 lunar days. | The agreement between the observed and calculated heights and times shown in the preceding Tables, is as close as can be expected in tidal observations, and indicates the degree of import- ance which should be attached to the diurnal tidal constants at Caherciveen. Section V. Diurnal Tide at Bunown. Separating the solar and lunar tides in the diurnal tide at Bunown, deduced from the observed heights by the method already described, I obtained the following results :— oT oo I. Diurnal tide in height at high water. . Maximum value of lunar tide for positive heights =0°20 ft. Maximum value of lunar tide for negative heights =0°28 ft. . Maximum value of solar tide =0°25 ft. . Diurnal solitidal interval = 25 52™, Age of lunar tide =4 9h, II. Diurnal tide in height at low water. . Maximum value of lunar tide for positive heights = 0°30 ft. Maximum value of lunar tide for negative heights =0°40 ft. . Maximum value of solar tide =0°25 ft. . Diurnal solitidal interval =2h 52™, . Age of lunar tide =44 9}, Adding the first two of each of the preceding, we find— Range of lunar tide at high water =0°48 ft. Range of lunar tide at low water =0°70 ft. 62 The Rev. 8S. Haughton on the Solar and Lunar Hence by equation (8), : 0-48 cot (m—t,) = O70 = cot (55°), or : m—i,,= 3) 47™ ; but since m, at high water, is the establishment expressed in Bunown time, and is 4" 18™, we find tim = 0b 31™. By equation (4), we have max. value of 2M sin 2u= (0°48)?+ (0°70)?=0°848 ft. ; from which we obtain M=0°646 ft. And since the maximum value of the solar tide is 0°250 feet, we have, by equation (5), max. value of 2S sin 2o6=0°500 ft., and therefore S=0°342 ft. Combining these results, we have as tide constants at Bunown, 1, Lunitidal interval =0 31™, 2. Solitidal mterval =25 52™, 3. Age of lunar tide at high water =44 9b. at low water =44 9h, 4. Lunar coefficient =0°646 ft. 5. Solar coefficient =0:342 ft. 6. Ratio of solar to lunar coefficient, S Lea Te te. or M =0°529. The solar and lunar tides at Bunown were constructed from the foregoing constants, and compared with the observed tides. The results of the comparison are given in thefollowing Tables:— Bunown Tide, Table A. Positive heights at high water for thirteen lunations, from 1851, January 104 164 42™, to 1851, December 314 11 36™, | No. | Observed. |Calculated.| Difference./| No, | Observed. |Calculated.| Difference. ft. ft, ft. ft. ft. ft. 1 0-41 0°39 +0:02 8 0:36 0°36 0:00 2 0:38 0°36 +0°02 9 0:25 0:33 —0:08 3 0:29 0:25 +0:04 10 0-21 0:21 0:00 4 0:12 0-13 —0:01 ll 0-16 0-138 +0:03 (75 0-20 0:20 0:00 12 0:23 0-20 +0-03 6 0:23 0-24 -—O001 13 031 0°30 +001 7 | 085 0-32 | +0-03 Mean difference = -+0:006 ft. Diurnal Tides of the Coasts of Ireland. Bunown Tide, Table B. 63 Negative heights at high water for thirteen lunations, from 1851, January 104 164 42™, to 1851, December 315 115 36", No. | Observed. |Calculated.| Difference.|| No. Observed. |Calculated.| Difference. ft. ft. fe ft. ft. ft. ft. 1 0°45 0:48 —0:03 8 0:47 0:47 0:00 2 0°37 0:39 —0:02 of 0:40 0°39 +0:01 3 0-24 0-31 —0:07 10 0-26 0-26 0:00 4 0°30 0-24 +0-:06 Il 0-14 0°24 —0:10 5 0°37 0-28 +0:09 12 0-35 0:33 +0:02 6 0-43 0:40 +0:03 13 0°40 0:44 —0:04 7 | 049 | 0-44 | +005 Mean difference = 0-000 ft. » Bunown Tide, Table C. Positive heights at low water for thirteen and a half lunations, from 1851, January 24 10554™, to 1852, J anuary 24175 39m, No. | Observed. [Cateulated. Difference. ft. 0:50 0:38 0-23 0-40 0-40 0°47 0-52 STD Ot CO DD ft. —0:02 —0:07 —0-12 +0°10 +0-04 —0-01 0-03 No. ft. 0-51 0-41 0:35 0-40 0-41 0-44 0:50 Observed. Icaleulated. Difference. Mean difference = —0-008 ft. Bunown Tide, Table D. Negative heights at low water for thirteen and a half lunations, from 1851, January 24105 54™, to 1852, January 24175 39m, No. | Observed. Calculated.| Difference. ft. 050 0°55 0-49 0:53 0:66 0°60 056 NS Orem Cobo ft. 0:56 0:47 0:40 0:43 0°56 0:64 0:62 ft. —0:06 +008 40-09 40-10 +0:10 —0-04 —0-06 No. Observed, |Calculated.| Difference. ft. 0:50 0:46 0:43 0:46 0:57 0:60 ft. —0'10 +0-01 —0-03 40-02 +0-03 —0:10 Mean difference = 40-008 ft. 64 On the Solar and Lunar Diurnal Tides of the Coasts of Ireland. Bunown Tide, Table E. Difference of observed and calculated times of vanishing of diurnal tide at high water. Age of lunar tide =4¢ 9}, | No. Difference. No. Difference, 1 —0-25 lunar days, 14 | —0-25 iunar days. 2 —0:20 ote Wee ki: +0:'60 awe 3 +1:60 16 —0'20 4 —0-20 iV; +0:55 5 | +2°75 18 —0:45 6 —0-20 19 —0°25 7 +0°75 20 —0:20 8 —0-20 21 +0°80 9 +0:50 22 —0:20 10 —3-00 23 +0°65 ll —1:20 24 —1°20 12°) +415 25 —0:25 13° | —0-20 26 —0°75 Mean =+0:001 lunar days. Bunown Tide, Table F. Difference of observed and calculated times of vanishing of diurnal tide at low water. Age of lunar tide =44 94, No. Difference. No. Difference. 1 —0°83 lunar days. 14 —0-08 lunar days. 2 — 0:03 a3 15 —0:58 445 3 +0°87 or 16 +0:97 4 — 0°38 Se 17 —0:58 5 +0:62 te 18 +0°12 6 +0:12 ats | 19 +1:27 7 +0:37 ie 20 —0°30 8 —053 ase 21 +0°12 9 —0:28 405 22 +0°37 10 +037 eae 23 —0°08 11 — 0-43 Roe 24 —0-48 12 —0-28 a 25 —0:53 13 —0:28 ans 26 +0:27 Mean =+0:003 lunar days. From the foregoing Tables, it will be seen that there is an ex- cellent general agreement between the observations and the tides calculated from the constants, and that these may therefore be relied on as very close approximations to the constants of the diurnal tide at Bunown. [To be continued. | peer A VI. On the Effect of Chlorine in Colouring the Flame of Burning Bodies. By D. Forses, F.G.S., F.C.S., ACE CONSIDERABLE time back, whilst examining some saline minerals for boracic acid, and employing the usual test as to the power of colouring flame green, when treated with sul- phuric acid and alcohol, it was found that a green flame presented itself, very similar to that which would be expected in case boracic acid were present in the minerals. On the most careful exami- nation, however, no traces of boracic acid could be detected, and it was evident that the coloration of the flame must have pro- ceeded from some other source. As chlorine was present in considerable amount in the mine- rals in question, it became interesting to see whether its presence might have produced the green colour; and the experiments made on the subject fully confirmed this view. A number of further experiments on the power possessed by chlorine to colour flame, led to the following conclusions, which are stated briefly, as the results themselves sufficiently explain the modus operand. Chlorides treated with concentrated sulphuric acid and a very small amount of alcohol, produced green flames ‘similar to those eliminated from borates under like treatment. Quantitatively, however, the flames were of less intensity ; that is, the same weight of aborate would produce considerably darker green flames than when a chloride was used. When chlorides were moistened with sulphuric acid and heated in the blowpipe flame, a faint green coloration was observed, which generally confined itself to the inner flame. When hydrochloric acid is dropped cautiously on the flame of, burning alcohol, a greenish tinge is observable. A jet of chlorine or of hydrochloric acid gas directed upon the flame of a.spirit-lamp or of coal-gas, produces a jet of green flame ; this was also found to be the case when (by means of a convenient burner) chlorine gas was passed into the centre of a flame of burning coal-gas, or of vapour of alcohol. When burning alcohol was injected into a globe filled with chlorine gas, the alcohol vapour continued burning at the mouth of the globe with a very flickering but often brilliant green flame. From the above experiments, it will be seen that chlorine has in itself a decided colouring action on the flame of burning bodies, which may consequently in some cases lead to its being con- founded with boron, as the green colour imparted to flame has hitherto been regarded as a most characteristic test of the latter element. When, as often happens, chlorine and boron occur together, this test consequently becomes nearly valueless. * Communicated by the Author. Phil. Mag, 8. 4, Vol. 11. No. 69. Jan, 1856. F [ 66 ] VII. On the Reciprocal Action of Diamagnetic Particles. Letter from Prof. Toomson to Prof. TynDALL. My pear Sir, Glasgow College, Dec. 24, 1855. HAVE been prevented until to-day, by a pressure of business, from replying to the letter you addressed to me in the Number of the Philosophical Magazine published at the begin- ning of this month. You ask me the question, “ Supposing a cylinder of bismuth to be placed within a helix, and surrounded by an electric cur- rent of sufficient intensity ; can you say, with certainty, what the action of either end of that cylinder would be on an external fragment of bismuth presented to it ?” In answer, I say that the fragment of bismuth will be repelled from either end of the bar provided the helix be infinitely long, or long enough to exercise no sensible direct magnetic action in the locality of the bismuth fragment. I can only say this with the same kind of confidence that I can say the different parts of the earth’s atmosphere attract one another. The confidence amounts in my own mind to a feeling of certainty. In every case in which the forces experienced by a little magnetized steel needle held with its axis reverse along the lines of force, and a fragment of bismuth substituted for it in the same locality of a magnetic field, have been compared, they have been found to agree. In a vast variety of cases, a fragment of bismuth has been found to expe- rience the opposite force to that experienced by a little ball of iron, that is, the same force as a little steel maguet held with its axis reverse to the lines of force; and in no case has a discre- pance, or have any indications of a discrepance, from this law been observed. I feel therefore in my own mind a certain von- viction, that even when the action is so feeble that no force can be discovered at all on the bismuth by experimental tests, such, in regard to sensibility, as have been hitherto applied, the bis- muth is really acted on by the same force as that which a little reverse magnet, if only feeble enough, would experience when substituted im its place. Now there is no doubt of the nature of the force experienced by the steel magnet, or by a little ball of soft iron, in the locality in which you put the fragment of bismuth. One end of a magnetized needle will be attracted, and the other end repelled bythe neighbouring end of the bismuth bar; and the attraction or the repulsion will preponderate according as the attracted or the repelled part is nearer. There is then cer- tainly repulsion when the steel magnet is held in the reverse direction to that in which it would settle if balanced on its centre of gravity. In every case in which any magnetic force at all can be observed on a fragment of bismuth, it is such as the steel On the Reciprocal Action of Diamagnetic Particles. 67 magnet thus held experiences. Therefore I say it is in this case repulsion. But it will be as much smaller in proportion to the force experienced by the steel magnet, as it would be if an iron wire were substituted for the bismuth core. Yet in this case the repulsion on the bismuth is very slight, barely sensible, or per- haps not at all sensible when the needle exhibits most energetic signs of the forces it experiences. You know yourself, by your own experiments; how very small is even the directive agency experienced by a steel magnet placed across the lines of force due tothe bismuth core. You may judge how much less sensible would be the attraction or repulsion it would experience as a whole, if held along the lines of force ; and then think if the corresponding force experienced by a fragment of bismuth sub- stituted for it is likely to be verified by direct experiment or ob- servation. I think you will admit that it is “ incapable of veri- fication,” as well as “incontrovertible” by any collation of the results of experiments hitherto made on diamagnetics. As to the concluding paragraph of my letter which you quote, you do me justice when you say you accept it as an expression of my “personal conviction that the action referred to is too feeble to be rendered sensible by experiment.” J will not maintain its unqualified application to all that can possibly be done in future in the way of experimental research to test the mutual action of diamagnetics under magnetic influence. On the contrary, I admit that no real physical agency can be rightly said to be “incapable of verification by experiment or observation ;” and I will ask you to limit that expression to experiments and obser- vations hitherto made, and to substitute for the concluding para- graph of my letter the following statement, written for publication three days later, and published in the same Number of the Ma- gazine as that to which you communicated my letter (Phil. Mag. April 1855, p. 247). “The mutual influence ” between rows of balls or cubes of bismuth in a magnetic field, “ and its effects ”” in giving a tendency to a bar of the substance to assume a posi- tion along the lines of force, “ are so excessively minute, that they cannot possibly have been sensibly concerned in any phenomena that have yet been observed; and it is probable that they may always remain insensible, even to experiments especially directed to test them.” I remain, my dear Sir, ' Yours very truly, Dr. Tyndall. Witiiam THomson, F2 [ 68 ] VIII. On the Action of Water upon certain Sulphomethylates. By Arravr H. Cuurcn, Esg.* N a former memoiry I have described the final products of the spontaneous decomposition of certain sulphomethylates : I there reserved for a future communication the full explanation of the reactions concerned. This explanation I believe I can now offer in the results of an experimental inquiry into the action of water upon the neutral sulphate of methyle. Now as the sulphomethylate of methyle, obtained by the mutual action of iodide of methyle and sulphomethylate of silver, is not to be distinguished from the sulphate of methyle procured by the distillation of a mixture of methylic aleohol and sulphuric acid, we have a special reason, besides the general reasons uni- versally known, for doubling the equivalent of sulphate of me- thyle, and representing it by the formula C*H®S?O% Then, too, it has been observed{ that sulphate of zthyle, by boiling with water, yields together with alcohol an acid solution, in which, after neutralization with carbonate of baryta, sulpheethy- late or isethionate (parathionate ?) and traces of methionate (?) of baryta are contained: also that sulphate of methyle undergoes analogous changes. Now we have seen that we may legitimately view the neutral sulphate of methyle as sulphomethylate of me- thyle. Hence the question arises, Is it not extremely probable, as the final organic products of the decomposition which sulpho- methylate of baryta suffers are the same as those resulting from the similar decomposition of the sulphate of methyle, that this latter body is really produced by the action of boiling water upon the sulphomethylate of baryta? In this case of the sulpho- methylate of baryta, 1t may be supposed that at first a double decomposition § occurs between two equivalents, as represented in the following diagram :— Ba SO* Ba SO# C2 H3 SO! Ba SO! BaSO* 4) __-—_c? H® 0! C2 H3 $0! C2 H8 SO! and, in the second place, that the sulphomethylate of methyle is transformed in the presence of water into methylic alcohol, and the stable sulphomethylic acid, according to the following equation:— C? H? SO* C? H? S04 C2 He? sot +2HO =C? H? O? + H ie * Communicated by the Author. + Phil. Mag. S. 4. vol. x. pp. 40-44. t By Wetherill, Ann. Pharm. vol. lxyi. p. 117. § Or possibly the formula of ordinary sulphomethylic acid is2(C?H*250%), while that of the B-acid is simply C7 H*2S0*. On the Action of Water upon certain Sulphomethylates. 69 Because of the identity in odour of sulphate of methyle and sulphomethylates undergoing decomposition, I am the more in- clined to believe that sulphate of methyle is produced by the action of boiling water upon certain sulphomethylates, or in their spontaneous metamorphosis ; although, mdeed, in the first case it can exist at any one time in minute quantity only, on account of its almost immediate re-solution into methylic alcohol and sulphomethylic acid. Of the truth of these ideas, which theory at first suggested, and experiment has since established, the present paper is in- tended to afford direct proofs: it also contains the results of an experimental inquiry as to the action of water upon sulphome- thylate of ethyle. To this latter inquiry my attention was directed by certain theoretical considerations: the following questions suggested themselves for solution :— Would C? H? SO? C* H® SO* ae So: } +2HO=C* Ho? OH sory + ( gasgelgey OTHERS or =C#H°024 H sot f Or would the reaction be more complicated, two equivalents of sulphomethylate of zthyle being concerned in it, as in the reaction with sulphomethylate of baryta which I have already described ; thus :— C?HsO]__ S08 CH SOS CHB S08 C2 H8 S04 >< 6H s08 1H i a C4 HS so: t And then in the second stage, the sulphomethylate of methyle and the sulphethylate of sthyle decomposing in the way pre- viously mentioned; thus :— C? H3 SO# 2 C? H? SO* C2 H? so: + 2HO = C H* 0? + H 50 and C+ H° SO? C+ H®SO* C4 He sort + 2HO=C4 Hé O? + Hi 0° Although chloride of methyle is without action upon sulpho- methylate of potash, yet if sulphomethylate of silver, iodide of methyle, and absolute aleohol*, be brought together and sub- mitted in a sealed tube to a considerable temperature in the oil- bath, iodide of silver will form, and after opening the vessel some * If water be present, methylic alcohol and sulphomethylic acid, together with a minute quantity of an indifferent oil, will occur instead of sulphate of methyle. 70 Mr. A. H. Church on the Action of Water quantity of crude sulphate of methyle may be distilled off. This liquid, as also the body obtained by the action of sulphuric acid upon methylic alcohol, when placed in water is slowly decom- posed at ordinary temperatures, almost instantaneously at 100° C. The chief products of this reaction are methylic alcohol and 8-sulphomethylic* acid. The acid produced differs from ordi- nary sulphomethylic acid. For if the acid solution + obtained by treating sulphate of methyle with water be saturated with car- bonate of baryta, a beautiful baryta salt may be obtained from it by evaporation, or by precipitation with strong alcohol ; the aqueous solution of this salt is not decomposable by ebullition, and the substance itself agrees in all its properties with the 8-sulphomethylate of baryta which I have already described. A portion of this salt dried at 100° C., gave by ignition and sub- sequent treatment of the residue with nitric and sulphuric acids, the following numbers :— ‘27 germ. salt furnished *175 grm. Ba SO*= 64:81 per cent., while theory, as C? H® Ba 2SO4, requires 64°9 per cent. Ba SO*. In whatever way the sulphate of methyle be prepared, and the transformation in contact with water effected, 8-sulphomethylic acid is invariably produced. Only once, indeed, have I obtained in this reaction traces of a baryta compound of the same com- position as the sulphomethylate, which was alterable at the boil- ing-point of water. The modified sulphomethylic acid is obtained from the methylic sulphate in a state of the greatest purity when water is allowed to act upon it at the ordinary summer tempera- ture ; when a greater degree of heat is employed, secondary de- compositions occur. The methylic alcohol produced in the reac- tions described is usually contaminated at first with a trace of sulphate of methyle, imparting to it an alliaceous odour. As it is only by processes of purification, in which a considerable loss takes place, that dilute methylic alcohol can be rendered perfectly anhydrous, and so fit for analysis, I have contented myself with ascertaining that the distillate which came over between 66° and 68° possessed a most considerable inflammability ; identifymg it with methylic alcohol by a few qualitative experiments, and pre- paring a baryta salt of the acid produced by treatment of this dilute methyle spirit with sulphuric acid. ,; The salt employed in the analysis last given was prepared from the product of the reaction between sulphomethylate of silver and iodide of methyle. An analysis of the salt made from sul- * For an account of this acid, which corresponds in the methyle series with the parathionic acid of the ethyle series, see Phil. Mag. 8, 4. vol. x. pp. 40-44. Wey : i + Occasionally a trace of free sulphuric acid is present in this liquid. upon certain Sulphomethylates. 71 phate of methyle obtained in the usual way gave this result :— *332 grm. salt, dried at 100° C., furnished by ignition 2155 grm. Ba SO*=64'9 per cent. Ba SO*. A brief account may now be given of the metamorphoses of the sulphomethylate of ethyle. Just as the product obtained by acting upon methylate of sodium with iodide of zthyle is not to be distinguished from the ethylate of methyle procured by the decomposition of zthylate of sodium by means of iodide of me- thyle, so sulphomethylate of sthyle is apparently identical with sulphzthylate of methyle, and yields the same products of de- composition when submitted to the action of water. To deter- mine the nature of this reaction, I kept sulphomethylate of ethyle together with water in a closed vessel in a warm place. When the oil had entirely disappeared, and the liquid had lost its original odour, the more volatile portion was distilled off from a water-bath: a highly acid liquid remained in the retort, while the distillate was inflammable. And now of this spirituous distillate. In the first experiment with sulphomethylate of zthyle, I attempted to concentrate the alcoholic product by means of recently burnt lime and anhydrous sulphate of copper. I obtained in this way a liquid almost ab- solutely anhydrous, and nine-tenths of which could be distilled over between 78°and 80°C. I was thus led to believe that sulpho- methylate of zthyle is decomposed in presence of water, chiefly, if not entirely, into ethylic alcohol and sulphomethylic acid; and consequently expected to find that the analysis of a baryta compound prepared by neutralizing the acid residue remaining in the retort would give the numbers required by theory for the sulphethylate of baryta. I accordingly made a determination of the sulphate of baryta in the salt obtained from the residue; it should be stated that the saturated aqueous solution of this salt was not alterable by continued ebullition :— ‘411 grm. of salt gave ‘2566 grm. of Ba SO*=62-43 per cent. This analysis indicates a mixture of the sulphomethylate with the sulphethylate of baryta nearly in the ratio 5:6. Other subsequent experiments seemed to show that the two acids are produced in equal equivalents. The apparent absence of me- thylic alcohol was soon accounted for. In fact it had entered into combination with the lime employed to deprive the alcohols of water; for by distillation, after the addition of water to this compound with lime, the methylic spirit was recovered, and after repeated treatments with anhydrous sulphate of copper a small quantity of the alcohol was obtained nearly pure, and boiling between 65° and 67° C. 72 Royal Society :— The more important conclusions to which my experiments have led me are these :— I. That by the action of water upon sulphate of methyle, B-sulphomethylic acid is produced. Il. That in the action of water upon sulphomethylate of baryta, sulphate of methyle is formed, and that then the decomposition roceeds according to (I.). III. That sulphomethylate of zthyle yields, by the action of water, methylic and zthylic alcohols, as well as 8-sulphomethylie and parathionic acids. December 1855. IX! Proceedings of Learned Societies. ROYAL SOCIETY. [Continued from vol. x. p. 456. ] June 21.—The Lord Wrottesley, President, in the Chair. HE following communications were read :— «On the Enumeration of v-edra having an (a—1)-gonal Face, and all their Summits Triedral.”” By the Rev. Thomas P. Kirk- man, A.M. The object of the paper is to enumerate the z-edra which have an (w—1)-gonal face, and all their summits triedral; or, what is the same thing, to find the number of the z-acra which have an (e—1)- edral summit, and all their faces triangular. Every z-edron having an (v«—1)-gonal face has at least two trian- gular faces. Let A be an z-edron having all its summits triedral, and having about its (e—1)-gonal face & triangular faces. Suppose all these triangles to become infinitely small; there arises an (r—k)- edron B, having an (c—A—1)-gonal face, and all its summits tri- edral. B will have &! triangular faces, /' being not less than two, nor greater than k. And there is no other (r—h)-edron but B, which can arise from the vanishing of all the & triangles of A; 7. e. there is no (rx—k)-edron but B, from which A can be cut by re- moving k of the summits of B in such a way as to leave none of its k' triangles untouched. If we next suppose the #! triangles of B to vanish, there will arise an («—k—k')-edron C, having an («—k—k'—1)-gonal face, all its summits triedral, and k" triangular faces, knot <2, nor >k'. And thus we shall at last reduce our 2-edron, either to a tetraedron, or to a pentaedron having triedral summits. All z-edra here considered fall into six varieties, differing in the sequence of the e—1 faces that are collateral with the (v—1)-gonal base. They are either irreversible, as the octaedron 6435443, the seven faces about the base reading differently both backwards and forwards from every face; or doubly irreversible, as the heptaedron Rey. T. P. Kirkman on x-edra having an (x—1)-gonal Face. 73 543543, whose six faces about the base are a repetition of an irre- versible period of three; or triply irreversible, as the decaedron 643643648, whose faces exhibit a thrice-repeated irreversible period ; or they are reversible, doubly reversible, or triply reversible, as the hexaedron 53443, the enneaedron 63536353, or the heptaedron 535353, exhibiting a single, double, or triple period, all reading backwards and forwards the same. If P, be the number of 2-edra having an (e—1)-gonal base, and all their summits triedral, Pe=le +] +1+Ry+ Re+Re, the symbols on the right denoting the numbers of w-edra of the six varieties that make up P,. Each variety is again subdivided according to the number of tri- angular faces. Thus, if P(2, k) denote the number of z-edra on an (w—1)-gonal base, having & triangular faces, and all their summits triedral, P(2, k)=I(w, k) + (a, k) + E(a, k) + Ra, b) + R(a, k) + BX(2, b). The number & is not <2, nor >, and P,=ZP(a, k), for all values of k. It is necessary to solve the following Problem.—To determine the number of (2 +4+/)-edra, none of which shall be the reflected image of another, that can be made from any z-edron having & triangular faces, by removing + / of its base-summits, thus adding 4+/ triangular faces, so that none of its k triangular faces shall remain uncut. The z-edron is supposed to have an (w—1)-gonal face, and all its summits triedral; no edge is to be removed, and k+/ not >#—1. When the z-edron, the subject of operation, is érreversible, all the resulting (c+4+/)-edra will be irreversible. If it is reversible, . some of them will be reversible and others irreversible ; if it is mud- tiple, some of them will be, and others will not be, multiple. If the subject of operation is irreversible, the number required by the problem is g—l1—f'!7} jal) r—1—2k! alo} ii(2,k,1) = 2", ————_— 3, (2°—1) .2°-*. —= . ———— ii(x ) Veo At ) a+l Pa taken for all values of a not greater than the least of & and /; i. e. k—a not <0, 0 not >/—a. The complete answer to the problem is expressed by the follow- ing equations, in which, of the capitals on the left, the first ex- presses the result, and the second the subject of operation. That is, IR?(z, k,/) denotes the number of irreversibie (v7+k-+/)-edra having k+/ triangular faces about the (2+k+/—1)-gonal base, that can be cut from any doubly reversible w-edron having / triangles about its (v—1)-gonal base. Whenever & or / in the function ii(a, k,/) is not integer, the func- tion, by a geometrical necessity, is to be considered =0, 74 Royal Society :— Il(2, k,l) =ii(a, k, 2), IP(2Qv +1, 2k, L)=H{ii(Qe+ 1, 2k, |) —ii(w+1, k, W)}, Il(3e+1, 3h, J) =2{ii(3a+1, 3h, 1) —ii(w +1, k, aD, PP (Qe-+1, 2k, 1) =ii(a +1, k, 3), EE (3e+1, 3k; 1) =ii(«@-+1, k, 4) ; RR(Qe+ 1, 2k, 1) =ii(e+1, k, 2), RRQe+1, 2k+1,) =ii(a, k, I—2)) RR(Qw, 2k, )=ii(e, k, 3) +ii(a, k, 4-1) 5 IR(20-+ 1, 2k, 1) =3{ii(Qe+1, 2k, 1) —ii(w@+1, k, 4D)}, IR(Qe+1, 2k +1, I) =}{ii(2e+1, 2k +1, 1)—ii(a, k, 4—2))} > IR (Qe, 2k, I) =2{ti(Qe, Qk, 1)—ii(a, k, 41) —ii(w, k, }U—1))} ; ROR?(40-+ 1, 4h, 1)=ii(w+ 1, k, 3D), PR2(4e-+1, 4h, 1) =2{ii(2Qv41, 2k, H)—ii(w+1, k, W)}, RR?(4e +1, 4k, 1) =ti(Que+1, 2k, 31)—ii(e@+1, hk, 1), IR?(4x+ 1, 4k, 1) =3[ii(4e+ 1, 4h, 1) + 2ii(w+1, k, Al) —3ii(2Qv+1,2k,4)]; R®R4(6a+ 1, 6h, 7) =ti(a +1, k, 4), R°R*(7, 3, 3)=1, PR*(6x +41, 6k, 1)=Z{ii(Qr+1, 2k, 1) —ii(w+1, k, d0)}, RR*(6x-+ 1, 6h, 1) =1i(3e+ 1, 3k, HM) —ii(w +1, k, 42), RR°(7,3,1)=2, IR*(62+1, 6k, J)=2{ti(6r+1, 6h, 1)+3ii(e+1, k, fl —ii(2x+1, 2k, 11)—3ii(32+1, 3k, 31}, IR(7, 3, 2)=1R*(7, 3, 1)=IR*(7,3,0)=1; ER™(2+1, ky v—k)=0. By the aid of the above, together with the following, equations, the (v+k+/)-edra having k+/ triangular faces, an (7+k+/—1)- gonal base and triedral summits, are successively found. I(a+k+l,kt+D)=3{l(et+h) (2, k,U)+ P(e, #) IP (a, #7) +P (a, Kk). IP (2, kh, U)+R(a, kh) . IR (2, #1) +R°(a, k') . IR*(a, 2, !) + R%(a, k') . IR%(a, k',1)}; &e.&e, taken for all values of kA! +-2/=k+. Similar equations are to be formed for the remaining five sub- divisions of P(v+k+1, k+l)" Of the products under &, the first factors are found by the pre- ceding part of the process, and the second are given by the equa- tions above written as solutions of the problem. The factors will of course frequently be zeros. Finally, if 2’ =v+k+J, Poy pe7=Py=P(a', 2)+P(a',8)+....+P(e', d(@!—1)) Mr. J. G. Jeffreys on British Foraminifera. 75 Thus, to give an example, P,,=P(11, 2)+ P(11, 3)+P(11, 4)+ P(11, 5) =1(11, 2)4+1(11, 3) +1(11, 4) + (I(11, 5)=0) +F(11, 2)+1(11, 4) +R(11, 2)+R(11, 3)+R(11, 4) + R11, 5). I(11, 2)=P(9, 2). IP(9, 2, 0) +1(9, 2). 1i(9, 2, 0) ; (11, 3) =1(8, 2). 11(8, 2,1) + R(8, 2). IR(8, 2,1) +1(8, 3) .1(8,3,0); 1(11, 4)=1°(7, 2) . IP(7, 2, 2) + R(7, 2). IR(7, 2, 2) +R*(7, 3). IR*(7, 3,1); P(11, 2)=F(9, 2) . PI°(9, 2, 0); Pe ye ( 7, 2) SP P7, 2; 2); R(11, 2)=R(9, 2). RR(9, 2, 0); R(11, 3)=R(8, 2). RR(8, 2, 1); R(11,4)=R(7, 2). R(7, 2, 2) + R°(7, 3). RR*°(7, 8, 1); R(11,5)=R(6, 2) . RR(6, 2, 3). The result is : P,=1,,4+1,+R,=61+7+12=80. “Notes on British Foraminifera.” By J. Gwyn Jeffreys, Bsq., F.R.S. Having, during a great many years, directed my attention to the recent Foraminifera which inhabit our own shores, I venture to offer afew observations on this curious group, as Dr. Carpenter, who has favoured the Society with an interesting and valuable memoir on the subject, seems not to have had many opportunities of studying the animals in the recent state. Rather more than twenty years ago I communicated to the Lin- nean Society a paper on the subject, containing a diagnosis and figures of all the species. This paper was read and ordered to be printed in the Transactions of that Society ;. but it was withdrawn by me before publication, in consequence of my being dissatisfied with D’Orbigny’s theory (which I had erroneously adopted), that the animals belonged to the Cephalopoda; and my subsequent ob- servations were confirmed by the theory of Dujardin. I have since placed all my drawings and specimens at the disposal of Mr. Wil- liamson of Manchester, who has given such a good earnest of what he can do in elucidating the natural history of this group, by his papers on Lagena and the Foraminiferous mud of the Levant. The observations which I have made on many hundred recent and living specimens of various species, fully confirm Dr. Carpenter’s view as to the simple and homogeneous nature of the animal. His idea of their reproduction by gemmation is also probably correct; although I cannot agree with him in considering the granules which are occasionally found in the cells as ova. These bodies I have fre- quently noticed, and especially in the Lagena; but they appeared 76 Royal Society :— to constitute the entire mass, and not merely a part of the animal. I am inclined to think they are only desiccated portions of the ani- mal, separated from each other in consequence of the absence of any muscular or nervous structure. It may also be questionable if the term “ova” is rightly applicable to an animal which has no distinct organs of any kind. Possibly the fry may pass through a metamor- phosis, as in the case of the Medusa. Most of the Foraminifera are free, or only adhere by their pseudo- podia to foreign substances. Such are the Lagena of Walker, Nodo- saria, Vorticialis and Textularia, and the Miliola of Lamarck. ‘The latter has some, although a very limited, power of locomotion ; which is effected by exserting its pseudopodia to their full length, attach- ing itself by them to a piece of seaweed, and then contracting them like india-rubber, so as to draw the shell along with them. Some of the acephalous mollusks do the same by means of their byssus. This mode of progression is, however, exceedingly slow; and I have never seen, in the course of twenty-four hours, a longer journey than a quarter of an inch accomplished by a Miliola, so that, in compari- son with it, a snail travels at a railroad pace. Some are fixed or sessile, but not cemented at their base like the testaceous annelids. The only mode of attachment appears to be a thin film of sarcose. The Lobatula of Fleming, and the Rosalia and Planorbulina of D’Orbigny belong to this division. Dr. Carpenter considers the Foraminifera to be phytophagous, in consequence of his having detected in some specimens, by the aid of the microscope, fragments of Diatomacee and other simple forms of vegetable life. But as I have dredged them alive at a depth of 108 fathoms (which is far below the Laminarian zone), and they are extremely abundant at from 40 to 70 fathoms, ten miles from land and beyond the range of any seaweed, it may be assumed without much difficulty, that many, if not most of them, are zoophagous, and prey on microscopic animals, perhaps even of a simpler form and structure than themselves. They are in their turn the food of mol- lusca, and appear to be especially relished by Dentalium Entale. With respect to Dr. Carpenter’s idea that they are allied to sponges, I may remark that Polystomella crispa (an elegant and not uncommon species) has its periphery set round at each segment with siliceous spicula, like the rowels ofaspur. But as there is only one terminal cell, which is connected with all the others in the interior by one or more openings for the pseudopodia, the analogy is not complete, this being a solitary, and the sponge a compound or aggregate animal. I believe the geographical range or distribution of species in this group to be regulated by the same laws as in the Mollusks and other marine animals. In the gulf of Genoa I have found (as might have been expected) species identical with those of our Hebridean coast, and vice versd. In common with Dr. Carpenter, I cannot help deploring the ex- cessive multiplication of species in the present day, and I would in- clude in this regret the unnecessary formation of genera. Another Mr. J. Joule on the Magnetism of Iron Bars. Ke Linnzeus is sadly wanted to correct this pernicious habit, both at home and abroad. The group now under consideration exhibits a great tendency to variation of form, some of the combinations (especially in the case of Marginulina) being as complicated and various as a Chinese puzzle. It is, I believe, undeniable, that the variability of form is in an in- verse ratio to the development of animals in the scale of Nature. Having examined thousands (I may say myriads) of these elegant organisms, I am induced to suggest the following arrangement :— 1. Lagena (Walker) and Entosolenia (Williamson). 2. Nodosaria and Marginulina (D’Orb.), &c. 3. Vorticialis (D’Orb.), Rotalia (Lam.), Lobatula (Flem.), Globi- gerina (D’Orb.), &c. 4. Textularia (Defrance), Uvigerina (D’Orb.), &c. 5. Miliola (Lam.), Biloculina (D’Orb.), &e. This division must, however, be modified by a more extended and cosmopolitan view of the subject, as I only profess to treat of the British species. To illustrate MacLeay’s theory of a quinary and circular arrangement, the case may be put thus. Lagenade. 1 Zz Miy 10la d. PS 5 zpr xesoP® The first family is connected by the typical genus Lagena with the second, and by /ntosolina with the fifth; the second is united with the third through Marginulina; the third with the fourth through Globigerina; and the fourth with the last through Uvige- rina. Whether these singular and little-known animals are Rhizopodes, or belong to the Amceba, remains yet to be satisfactorily made out. London, June 18, 1855. “ Preliminary Research on the Magnetism developed in Iron Bars by Electrical Currents.” By J. P. Joule, F.R.S. The author had, many years ago, found that the magnetism deve- loped by electro-magnetic coils in bars of upward 4rd of an inch diameter, was nearly proportional to the strength of the current and the length of the wire, any alteration, within certain limits, of the diameter of a bar being attended with only trifling effects, so long as the point of saturation was not nearly approached. The Russian philosophers Lenz and Jacobi had, however, stated that the mag- netism developed was, ceteris paribus, proportional to the diameter of the bar, ‘lhe discrepancy between the above results is considered 78 Royal Society. by the author to be owing rather to the different circumstances under which the experiments were tried than to any inaccuracies in the experiments themselves. Further, it appeared to him that in any case of induction by electric currents, careful distinction should be made between the several effects, which, compounded together, constitute the total magnetic action. Especially should a distine- tion be made between the magnetism existing under the inductive influence of. the current and that permanently developed so as to remain after the electrical circuit is broken, and therefore the first efforts of the author were directed to ascertain the laws which regu- late this permanent effect, or, as he thinks it may be conveniently termed, the magnetic set. In his experiments the magnetism of any bar was ascertained, by placing it vertically with its lower end near a delicately suspended magnetic needle. This was a piece of sewing-needle 3,ths of an inch long, furnished with an index of fine drawn glass tube tra- versing over a graduated circle six inches in diameter. It was sus- pended by a filament of silk. The tangent of the deflection of the needle was found to be the exact measure of the attraction of a bar. In working with this instrument, it was found that the resistance of the air prevented the needle from swinging even once beyond the point of equilibrium to which it always arrived in less than ten seconds. ‘This resistance of the air, so useful for bringing the needle rapidly to a state of rest, rendered it necessary to keep the entire instrument at a uniform temperature, for the slightest local application of heat produced currents of air within the glass case of sufficient strength to occasion considerable deflections. The cir- cumstance points to the possibility of constructing a new and very sensitive thermometer which might be useful, particularly in experi- ments on the conduction of heat. The method of experimenting consisted in observing,—Ist. the magnetic attraction of any bar when a current circulated through its spiral; 2nd. the attraction still subsisting after the circuit was broken; 3rd. the attraction of the other pole of the needle on the reversal of the current; and 4th. the attraction remaining after this reverse current was cut off. The sum of the lst and 3rd observations gives the total change in the magnetism of a bar by the reversal of the current. ‘The sum of the 2nd and 4th gives the total permanent change of magnetism, or the magneiic set. The experiments were made with iron bars of the several dia- meters, =, 75» $ 4 2» and one inch, the length being in each case one yard; and also with iron bars 4, +, $ and one inch diame- ter, of the length of two yards. In all the bars of small diameter up to 4 of an inch, the magnetic set obtained by the use of feeble currents was found to be proportional to the square of the current employed in producing them. ‘This law was found to subsist through a long series of electric intensities; but when the current ‘was increased to a certain amount, the set, as observed in the bars of =; and =, of an inch diameter, increased in a much higher ratio, so as to vary, in some instances, with the 4th and 6th powers of Geological Society. 79 the current. The point at which this phenomenon takes place is called the magnetic breaking point. A further increase of the cur- rent was attended with a rapid decrease of this ratio as the satura- tion of the bar was approached. The total change of magnetic condition by reversal of the cur- rent, minus the magnetic set, is found to be nearly proportional to the intensity of the current. Results of exactly similar character were obtained by the use of an electro-magnet, consisting of a bar of hard steel j of an inch in diameter and 73 inches long. In conclusion, the author points out the striking and instructive analogy which exists between the above phenomena and those of the set of materials as exhibited by Professor Hodgkinson, who, in his admirable researches, has proved that the set, or permanent change of figure, in any beam is proportional to the square of the pressure to which it has been exposed. GEOLOGICAL SOCIETY. November 5, 1855.—Mr. W. J. Hamilton, President, in the Chair. The following communications were read :-— 1. “On the Coal of the North-western Districts of Asia Minor.” By Mr. H. Poole ; communicated by the Foreign Office. Mr. Poole, in his reports to the Government on the result of his journey to Asia Minor, to examine into the probability of workable coal being found in the country near Brussa and Ghio (Bithynia), in which coal had been reported to occur, states that he travelled from Ghio to the Lake Ascania, and around its shore, without finding any trace of coal; then from Yallova inland to Ortokoi, with like result. He next went from Yallova westwards along the coast as far as Kor- nikoi, where a bed of lignite, 9 inches thick, was worked to some extent by the Armenians four years since; thence he went inland to Sulmanli without seeing any indications of coal. In consequence of rumours of the existence of coal near the Lake of Apollonia, Mr. Poole travelled round that lake, but met with none. Mr. Poole next went from Yallova south-eastwardly to Tchougnoorkoi, where lignite, varying from 1 to 4 feet in thickness, and dipping at a high angle, has been also worked by the Armenians.. This lignite is of no pro- mise. Another excursion was to the Lake Sabandji, where a thin seam of lignite crossing the road on the south of the lake, and a lig- nite at Ag Sophé, to the east of the lake, were visited. Nowhere did Mr. Poole find proof of the existence of good workable coal in the districts visited. 2. “On the newer Tertiary Deposits of the Sussex Coast.” By Mr. R. Godwin Austen, F.G.S. From Brighton, westwards, between the chalk hills and the sea, the surface of the country is formed, first, by a raised terrace of “red gravels,” lying on the sloping base of the chalk hills, and on the old tertiary deposits; secondly, the gravels of the Chichester levels, or 80 Geological Society :— the “white gravels.’’ These latter are distinctly bedded and seamed with sand, and are more water-worn than the red gravels which pass under them; thirdly, the white gravels are overlaid by “brick-earth, ” which is somewhat variable in its characters. These, with their equi- valents, are the glacial deposits of the district in question. The coast sections, though very limited in extent, exhibit several important phe- nomena illustrative of the history of these newer tertiary accumula- tions. At Selsea, where the glacial deposits are about 25 feet thick, the underlying eocene clay is seen, at extreme low water, to be per- forated by a very large variety of Pholas erispata, and to be overlaid by a deposit containing Lutraria rugosa, Bullastra aurea, Tapes decussata, and Pecten polymorphus, contemporaneous with the Pho- lades. Elsewhere brown clays, or local ferruginous gravels, cover unconformably the eocene beds. The surface of the brown clay is deeply eroded, and bears a yellowish clay, which contains large chalk flints, and a great variety of pebbles and boulders of granitic, slaty, and old fossiliferous rocks, such as are now found in the Cotentin and the Channel Islands. One boulder of porphyritic granite measures 27 feet in circumference. A few sea shells (Littorina, &c.) occur in the yellow clay. This deposit the author regards as the equivalent of the ‘‘white gravel” in its extension southwards, the gravel having been littoral, and the clay with boulders a deposit formed in somewhat deeperwater of this portion of the glacial sea. The coast-sections ex- hibit the surface of the yellow clay as having been eroded and covered by a variable deposit, sometimes gravelly and sometimes sandy, and containing marine shells (Cardium edule, Ostrea edulis, Turritella terebra, &c.). This band contains also fragments of the old crystal- line rocks obtained from the destruction of the underlying yellow clay. On the shelly and pebbly band lies the brick-earth, an unstra- tified earthy clay deposit, with small fragments of flint and a few pebbles, and with occasional silt-like patches. The particular subject of this paper was the occurrence of the granitic and slaty detritus in the yellow clay. These blocks are especially numerous near Bracklesham, Selsea, and Pagham. The author explained the difficulties that lie in the way of supposing that they were derived from the Cornwall coast, or direct from the shores of Brittany or the Channel Islands. His previous observations, however, on the bed of the English Channel had prepared the way for the explanation of the hypothesis he now advanced—of the former existence of a land-barrier, composed of crystalline and palzeozoic rocks, crossing from Brittany to the south-east of England, and forming a gulf or bay open to the west. Into this bay the marine fauna represented by the Pholas crispata and its associates extended from the westward; and in the hollow of the bay, at a rather later period, coast ice brought the boulders from along the old shore line, which is now represented by a sunken peak in mid- channel and a shoal of granitic detritus. Alteration of level succeeded ; and the partial destruction of the yellow clay deposit afforded the overlying pebble bed, and, in the author’s opinion, the granitic blocks found in the old raised beach at Brighton. Mr. Godwin Austen Mr. J. Prestwich on an Artesian Well at Kentish Town. 81 thinks it probable that the superficial brick-earth of the district under notice was formed in a land-locked lagoon, subject to periodical freezing; and that the “elephant bed” at Brighton is one of its many and variable equivalents (in this case probably subaérial). The brick-earth area has been subsequently encroached upon by the estuaries of Pagham, Portsmouth, &c. ; and the successive oscillations in the level of the land are evidenced in the estuarine deposits and submerged forests of Pagham, Bracklesham, Portsmouth, &e. With regard to the latest movements, the author’s observations showed that from Lewes Levels to Chichester Harbour, and on to Hurst Castle, the coast exhibits signs of undergoing elevation at the present day. The coast of the Isle of Wight opposite seems on the contrary to be suffering depression, whilst the back of the island exhibits some curious signs of local oscillation. November 21, 1855.—W. J. Hamilton, Esq., President, in the Chair. The following communications were read :— 1. ‘‘ Notice of the Artesian Well through the Chalk at Kentish Town.” By Joseph Prestwich, Jun., Esq., Sec. G.S. The boring of this well has pierced the following succession of beds :—London Clay, 236 feet,—Woolwich and Reading series, 614 feet,—Thanet Sands, 27 feet,—Middle Chalk (usually termed “« Upper Chalk ” in England), 2443 feet, Lower Chalk, 2275 feet,— Chalk marl, 172 feet,— Upper Greensand, 59 feet,—Gault, 85 feet,— and then 1762 feet of a series of red clays with intercalated sandstones and grits. Altogether amounting to 1290 feet. It was expected that, in accordance with the general relations of the lower members of the Cretaceous series as they come to the surface in the districts North and South of London, that the sands of the Lower Greensand formation would be found immediately to succeed the Gault in the boring. Instead of the sands in question the red sandy clays have presented themselves, and the question of the probability of obtain- ing a supply of water by deeper boring depends upon the fact whether these red clays are a local variation of the Gault, and over- lie the usual Lower Greensand, or whether the lower Cretaceous deposits have here put on a new character altogether. The very few fossils met with in the Clays speak strongly in favour of their being true middle Cretaceous lying above the horizon of the Lower Greensand; but the occasional occurrence in the clay of large rolled fragments of syenite, porphyry, basalt, hornstone, and old sandstone, and its general mineral features, seem to indicate a littoral character for these deposits, and to point to the possible neighbourhood of a ridge of older rocks, which have modified the conditions under which the lower cretaceous beds were formed in this area. The considera- tion of this important subject was referred to a Committee, who will report upon it at a future meeting of the Society. Phil. Mag. 8. 4. Vol. 11. No. 69. Jan. 1856. G 82 Geological Society :— 2. ‘On the discovery, by Mr. Robert Slimon, of Uppermost Silu- rian rocks and fossils near Lesmahago in the South of Scotland, with observations on the relations of those strata to the overlying Palzo- zoic rocks of that part of Lanarkshire.” By Sir Roderick I. Mur- chison, V.P.G.S. &c. The principal object of the author is to direct the attention of geologists to the recent discovery of the uppermost Silurian rocks of Scotland, in which country their presence was unknown. This important discovery was made by Mr. Robert Slimon of Lesmahago, who in the western part of that extensive parish of Lanarkshire detected very remarkable and large fossil crustaceans, the exhibi- tion of which at the Glasgow meeting of the British Association induced Sir R. Murchison to visit the tract in question, accompanied by Professor Ramsay. The descending order of the strata is well seen on the banks of the Nethaw river, Logan water, and other small streams; all tributaries of the Clyde. There the lower carboniferous rocks, composed of several bands of Productus and Encrinite limestone, frequent seams of coal and layers of ironstone, including the celebrated “black band,” are underlaid by the Old Red Sandstone, as largely exposed between Lanark and Lesmahago. Towards its lower part the Old Red is marked by a powerful band of pebbly conglomerate ; whilst its base is made up of alternating red and light greenish-gray flagstones and schists. The latter are succeeded by dark gray, slightly micaceous, flag-like schists, charged with large crustaceans and other fossils, which organic remains, combined with the apparently conformable infra- position of the beds to the lowest Old Red, have led the author un- hesitatingly to consider the Lanarkshire strata to be the equivalents of the uppermost Ludlow rock or the Tilestones of England. These dark gray fossiliferous layers are underlaid by, and pass down into, athick accumulation of similar mudstones, which becoming in some parts slightly calcareous, in others arenaceous, rise up into a district of round-backed moorland hills, ranging in height from 1600 to 2000 feet above the sea; the whole tract having been much penetrated by porphyries and other igneous rocks. The uppermost Silurian rock of Lanarkshire contains a species of Pierygotus not to be distinguished from the species of that crusta- cean so abundantly found in the upper Ludlow rock of Shropshire and Herefordshire ; like which the Scotch stratum holds the Lingula cornea and Trochus helicites? (Sil. Syst). The Lesmahago deposit is further characterized by the crustaceans of the group of Euryp- teride (Burmeister), which are described by Mr. Salter under the name of Himantopterus. ‘They are accompanied by another crus- tacean, the Ceratiocaris. In conclusion, Sir Roderick pointed out the remarkable persistency of this zone of large crustaceans in various parts of the world; one of the Lanarkshire individuals has a length of about 3 feet! In Westmoreland (Kendal) the Hurypterus is found in the Tilestones, with many upper Ludlow fossils ; in Podolia the stratum containing Mr. J. W. Salter on new Fossil Crustaceans. 83 the Hurypterus tetragonophthalmus (Fischer) underlies Devonian rocks; and in the Russian Baltic island of Oesel, it has recently been detected by M. Eichwald in a limestone which had been referred by the author and his associates to the Ludlow rock. In North America the Eurypterus occupies the same geological horizon as in Russia and the British Isles; and it is to be remembered that large crustaceans of this group of Eurypteride have nowhere been found in rocks of older date than the Upper Silurian. 3. ‘‘ Description of the Crustaceans from the Uppermost Silurian rocks near Lesmahago.” By John W. Salter, Esq., F.G.S. The large Crustacea referred to in the last paper were described by Mr. Salter. They belong to the family Eurypteride of Bur- meister, and bear the closest relation to Hurypterus. They also present many analogies with the Pterygotus, particularly in the presence of a scale-like sculpturing on the body-rings, a character now known to be present in Eurypterus, and probably common to the whole family. They are elongate crustaceans, with a comparatively short cara- pace, bearing the large sessile eyes on the margin (and not on the surface, as in Kurypterus), with ten or eleven body-rings unpro- vided with any appendages, and with a caudal joint either pointed or deeply bilobed. There are a pair of limbs adapted for swimming, a pair of maxille with serrated edges, and an anterior pair of long appendages with dilated bases, in all probability antenne (Hurypterus has two pairs developed). From the strap-shaped or ligulate form of the swimming-feet, the name Himantopterus is proposed in con- trast with Hurypterus, which has these organs dilated. Five or six species were described ; all new. 1. H. acuminatus ; a foot long, with a mucronate caudal appendage. 2. H. bilobus; 7 inches long, the tail bifid. 8. H. lanceolatus, a smaller species, with a simply pointed apex. 4. H. maximus. The head only known; it must have been 3 feet long when perfect, and is the largest known. (Pterygotus may have been about the same size.) 5. H.? simulans. A large species, with very distinct sculpture. 6. H. Banksii. A small species from the Tilestones of Kington, Herefordshire ; 3 or 4 inches long. A note by Mr. Huxley, on the relations of these gigantic extinct Crustacea, showed that their zoological position was neither among the Phyllopods nor the Peecilopeds, nor intermediate between the Copepods and Isopods, as had been supposed, but that their struc- tural peculiarities were to be paralleled only among the Cumoid Stomapods on the one hand, and the zozform larve of the Macrura on the other. Drawings of a new genus of Cumoid crustacea, Ca- lyptoceros, illustrated this position; and leaving out of considera- tion the Isopoda, Peecilopoda, and Trilobita, it was shown that the Eurypteridz exhibited the most rudimentary and larval forms of any known Crustacea. ; G2 84. Geological Society :— December 5, -1855.—W. J. Hamilton, Esq., President, in the Chair. The following communications were read :— 1. ‘‘On the Tilestones, or Downton Sandstones, in the neigh- bourhood of Kington, and their contents.” By R.W. Banks, Esq. Communicated by Sir R. I. Murchison, V.P.G.S. In the Bradnor Quarry near Kington, on the borders of Radnor- shire and Herefordshire, the Tilestones and Downton Sandstone are seen to overlie the Ludlow rock in the following descending order : —1l. thin tilestone; 2. wall-stone, 12 feet thick, unfossiliferous ; 3. mudstone, 3 to 6 inches, coloured grey by the intermixture of vegetable matter, and containing fragments of Pterygotus, and other crustacean remains, together with fossils allied to Cephalaspis Lyellit and C. Lewisii (Agas.); 4. Downton sandstone, 3 to 4 feet, with Lingula cornea, Trochus helicites, Pterygotus, and Cephalaspis-like fossils as above; 5. another grey mudstone, similar in character and contents to No.3; 6. yellow sandstone and flagstone, 4 feet, with the Cephalaspis-like fossils, Pterygotus, Leptocheles, and Trochus helicites; 7. Ludlow rock. Another section in the neighbourhood exhibits thin shaly beds of tilestone, with Lingula cornea, underlaid by layers of flattened Orthonota amygdalina and Trochus helicites, which rest on the equivalent of the Ludlow bone-bed, here about 2 or 3 inches thick, and containing Orthoceras gregarium, O. politum, Goniophora cymbeformis, Orthonota amygdalina, Orbicula rugata, Holopeila, Chonetes lata, Cornulites serpularius, Cucullella antiqua, Modiolopsis levis, Rhynchonella, Bellerophon carinatus, Leptocheles, Onchus tenuistriatus, Sphagodus, and Serpulites. The organic remains of these tilestone, sandstone, and mudstone beds were illustrated by numerous highly finished drawings by the author; and these, together with his descriptive notes, indicated the existence of one or more hitherto unknown or little understood forms of Crustacean life, probably of the Eurypteride group, and elucidated several important characters in the carapace and append- ages of the Pterygotus; with regard to which genus, Mr. Banks finds reason to differ from the generally received opinion that it was allied to Limulus and the Peecilopods. Mr. Banks’s specimens of the fossils resembling Cephalaspis Lyellii and C. Lewisii offer considerable evidence towards invalidating the Ichthyic relationship of these fossils, and placing them amongst the Crustacea. In conclusion—from the absence of the numerous Mollusca cha- racteristic of the Ludlow rocks, and from the presence of Crustacea that have not been found in the Ludlow beds, and especially the abundance of the Péerygotus, so characteristic of the Middle Old Red of Scotland,—the author is inclined to separate these Downton or Tilestone beds from the Upper Ludlow Rocks, and class them (as Sir Roderick Murchison, previously to his later remarks on the sub- ject, originally arranged them) as the bottom-beds of the Old Red Sandstone. Mr. D. Sharpe on the last Elevation of the Alps. 85 2. “ On the last Elevation of the Alps, with notices of the Heights at which the Sea has left traces of its action on their sides.” By Daniel Sharpe, Esq., F.R.S. & F.G.S. The object of this paper is to show that after the Alps had assumed their present form, the whole region was submerged below the sea, and stood 9000 feet lower than at present; and that it then rose out of the sea by a succession of unequal steps, separated by long intervals of time, during which the waves produced impressions on the sides of the Alps which are still visible. These effects are traced out under three heads: 1st. The erosion of the sides of the mountains, producing rounded forms which extend up to definite lines, above which the mountains rise into rugged peaks, in striking contrast with the smoother forms below. This change of form had been observed by Hugi, who referred it to different composition of the rocks ; by Agassiz and Desor, who seeing that Hugi’s view was incorrect, explained it by the action of moving ice, to which they arbitrarily assigned a definite upper limit; and lastly by Prof. J. Forbes, who has pointed out similar phenomena in Norway at 1500 or 2000 feet elevation. Mr. Sharpe shows that throughout Switzer- land these lines of erosion occur at three definite levels of 4800, 7500, and 9000 English feet above the sea, and he argues that no action but that of water could have produced a uniformity of level over so large an area, and that it required a long period of time to have formed such deep indentations of the mountain sides. 2nd. The sudden change of steepness which occurs at the head of every Alpine valley is assumed to be due to the excavating action of water, standing for a long period at that height: and a table is given of the elevation above the sea of the heads of between forty and fifty valleys, at various altitudes, which shows a correspondence of level between valleys on the opposite sides of the Alps, and between the excavation of several valleys and the lines of erosion at 4800 and 7500 feet; while the ice and snow in the higher valleys prevent a comparison with the highest line at 9000 feet. 3rd. The terraces of alluvium in the valleys are considered, in accordance with the opinion of Mr. Darwin, Mr. Yates, and others, to have been formed by detritus carried down into water standing at the level of the head of the terrace. The elevation of many of these terraces is given, and a correspondence is shown of the height above the sea of terraces in valleys which have no connexion with one another, and of terraces in some valleys with the heads of other valleys. Ali these effects might be produced by a sea surrounding the Alps, and cannot be otherwise explained; and the level of this sea being assumed to have been constant, the Alps must have been rising out of the waters while these operations were going on. The period of this, their last elevation, is stated to have been after the ‘Tertiary epoch; and a great part of the vast accumulations of sand, gravel, and rounded blocks which are seen in the valleys of the Alps and covering the lowlands of Switzerland are considered to have been 86 Intelligence and Miscellaneous Articles. formed by the waves beating against the mountains during their elevation. Lastly, referring to the angular erratic blocks on the sides of the Jura, &c., the author points out that he removes the only serious difficulty opposed to the views of those who have supposed them to have been transported by floating ice, by showing that the levels at which those blocks are found were below the sea for a long period at the epoch of their removal. X. Intelligence and Miscellaneous Articles. TWO PROCESSES BY WHICH THE PHHZNOMENON OF COLOURED RINGS MAY BE PRODUCED WITH GREAT INTENSITY. BY M. CARRERE. W HEN a drop of a solution of bitumen of Judea in a mixture of benzine and oil of naphtha is let fall upon the surface of some water in a vessel, a very brilliant luminous phenomenon is seen to be immediately produced. The bituminous liquid extends regularly in a thin film on the surface of the water, and thus pro- duces very bright colours. The colour furnished by the film changes every moment for a minute or two, because a portion of the benzine and oil of naphtha evaporates, and the thickness of the film dimi- nishes. But in a little time the film itself is completely solidified, from the oxidizing action of the air. This delicate solid film may be easily fixed upon paper. Thus, supposing that it has been produced in a tub at the bottom of which there is a socket with a stop-cock, and which also contains a stool, upon which, immersed in the water, rests the leaf of paper to be coloured; the film having been formed above the paper, all that is necessary to fix it on the paper is to open the stop-cock. To obtain a regular coloration of the paper by means of the bitu- minous film, it is very important that the latter should be very co- herent. I increased its cohesion by introducing a certain amount of caoutchouc into the solution of bitumen of Judea. I also obtain the phenomenon of coloured rings with great bril- liancy by exposing to the air hot and freshly-filtered common ink, in which sugar is the principal adhesive matter. This process may serve for the study of the phenomenon of coloured rings. In fact, as the thickness of the film which forms at thesurface of the ink only increases very slowly, we may very easily and exactly determine the order in which the different tints produced by a homogeneous film succeed each other in proportion as its thickness augments. I have also suc- ceeded in fixing on paper the film produced by ink; but as in this case the cohesion of the pellicle is very slight, I have only succeeded by taking the following precautions :— 1. I do not deposit the film upon the paper until it has acquired a great thickness. Meteorological Observations. 87 2. I choose bibulous paper to be coloured. 3. Before drying the paper, I impregnate it with a solution of gelatine.—Comptes Rendus, Dec. 10, 1855, p. 1046. ON A NEW SEISMOMETER. BY M. KREIL, DIRECTOR OF THE IMPERIAL METEOROLOGICAL INSTITUTE, VIENNA. The new seismometer (an instrument for determining the data con- cerning earthquakes), invented by M. Kreil, is a pendulum oscilla- ting in every direction, but unable to turn round on its point of suspension, and bearing at its extremity a cylinder, which, by means of mechanism within it, turns on its vertical axis once in twenty-four hours. Next to the pendulum stands a rod bearing a narrow elastic arm, which slightly presses the extremity of a lead-pencil against the surface of the cylinder. As long as the pendulum is quiet, the pencil traces an uninterrupted line on the surface of the cylinder; but as soon as it oscillates, this line becomes interrupted and irre- gular, and these irregularities serve to indicate the time of the com- mencement of an earthquake, together with its direction and inten- sity.—Proceed. Imp. Acad. Sciences, Vienna, March 8, 1855. METEOROLOGICAL OBSERVATIONS FOR NOVEMBER 1855. * Chiswick.—November 1. Cloudy : frosty at night. 2. Overcast and cold : heavy rain. 3. Showery. 4. Fine. 5. Clear: dense fog: very fine: rain. 6. Fine. 7. Cloudy. 8. Constant heavy rain. 9. Slight fog: fine. 10. Foggy: very fine: foggy at night. 11. Very fine: cloudy. 12. Hazy. 13. Overcast. 14. Fine: frosty at night. 15. Frosty and foggy: very fine: dense fog at night. 16. Dense fog. 17. Fine: cloudy: rain. 18. Hazy: cloudy: rain. 19. Rain. 20. Drizzly: fine. 21. Overcast: rain. 22. Drizzly: overcast: fine. 23. Cloudy. 24. Cloudy and cold: showery. 25. Cloudy: clear: sharp frost at night. 26. Very fine. 27. Overcast: slightrain. 28. Overcast: cloudy: lunar rainbow at 10 p.m. 29. Overcast: cloudy. 30. Overcast: very fine. Mean temperature of the month ........cssssseseesessseeeeseeees 40°84 Mean temperature of Nov. 1854 .........0+8 seaperees Sarcepaan « 39°35 Mean temperature of Noy. for the last twenty-nine years ... 42°95 __ Average amount of rain in Nov. ....... Sbscvssaente aheenaare ee. 2°347 inches. Boston.—Nov. 1. Fine. 2. Fine: raine.m. 3. Cloudy: rainp.m. 4. Fine: rain A.M. 5. Cloudy: rainp.m. 6. Raina. 7. Cloudy. 8. Cloudy: rain AM.andp.M. 9. Fine. 10. Cloudy. 11. Fine. 12—15. Cloudy. 16, 17. Fine. 18, 19. Cloudy: rainr.m. 20. Cloudy. 21. Cloudy: rain p.m. 22, 23. Cloudy: rain A.M. and p.m. 24. Cloudy: raine.m. 25. Cloudy. 26. Fine. 27. Cloudy: rain e.m. 28. Cloudy: rain A.M. andv.m. 29. Cloudy: raine.m. 30. Cloudy. * The observations by the Rev. C. Clouston of Sandwich Manse, Orkney, have not been received. | €.0b |g6.€€ |eZ.z+ Sie eee - = an re re 6c6.6c 0386.62 St0,08 610.0€ £96.62 1b7Z.08 £v0.0£ 618.62 0$ 2.62 $gL.6z $£3.6¢ 148.62 O10,0£ ogt.o£ Sgr.of Lgt.oft 40,08 6%6.6z 2L6,6z 060,08 9r.0€ Log.6z 1$L.6z Lgv.6z 299.62 936.62 Ig1.0f £96.62 919.62 648.62 £99.62 “ONT 070.08 gLo.of TI1,0f£ ZII.Of£ $£0.08 637,08 LLZ,0& $26.62 t9L.6z g78.6z 638.62 £00,0€ 690,08 1L1.0f £27,08 VEz.O£ Bgr.of goo.of Z10,0£ ZBI.0£ 9tz.0€ Sto.0f 108.62 LgS.6z L$8.6z gIr.0f Ogt.o£ fz1.0€ LLg.6z LzL.6% tol.6z “xB *TMSITTO “UR "of 6z “gz Lz, “92 Sz “bz *EzO a4 ‘IZ - 19.67 ZO. eececccce “MU “Mm gf gz St £9.62 2 a betes eels 1b] £6 | Sb $1.62 Lo, 10. ‘auu | ‘ou fv] of | LP oL.6z streeeeeel TO, “mun | au 6£| zp | LY oL,6z S SONtES ‘u | cau ££! of cad 00,0£ +r. | ou | ‘ou 6} gr | ty ape oz. l-guu | -u Iv] LE £v VS.6z Bee Weekes: red eae LE| ve | ty £+.62 61. Io. ‘asa | ‘au fim| Le | ev £v.62 ecccccece Zo. “9 ‘Ou ov gf f+ 35.62 10, -|* for ‘a | ‘au rv| L¢ | 2L.6z Lo, |\"So; ‘gua | ‘a S.zb} gf | LY 84.62 sreseeres! go, son eat S.ob| 66 | Lb $3.62 aasaercal see oiees Bee hedn §,of| 15™, and ending 1851, December2243433™. No. | Observed. |Calculated.| Difference. ft. 0-62 031 0:30 0:40 0°56 0°45 0°52 “TO Crm Co bo = ft. 0:52 0:39 0°33 0:36 0:52 0:54 0:57 ft. 40°10 —0-08 —0-03 +0-04 +0:04 — 0:09 —0-05 No. 8 9 10 11 12 13 Observed. ft. 0:40 0:28 0:40 0:57 0°54 061 ft. 0:49 0°40 0-36 0:43 0:50 0:57 Calculated. Difference. ft. —0-09 —0-12 +0-04 40-14 40-04 +0-04 Mean difference = —0:001 ft. Diurnal Tides of the Coasts of Irelund. ‘121 Cushendall Tide, Table D. Negative heights at low water for thirteen lunations, commencing 1851, January 0714"15™, and ending 1851, December 2243533™. No. | Observed. Calculated. Difference.| No. | Observed. |Calculated.| Difference. ft. ft ft. ft. ft. | ft. ] 0:54 0°52 +0:02 8 0-65 0°54 +011 2 | 057 | O51 | +0-06 9 | 050 | 0-47 | +0-03 3 0:37 0:40 —0-03 10 0°47 0-49 | —0:02 4 0°52 053 | —0-01 1] 0:57 054 | +0-03 a 0:54 0:59 —0-05 12 0-60 0°64 —0°04 6 0-60 0:69 —0:09 13 0:72 0:69 +0:03 7 0-60 0:67 —0:07 | Mean difference = —0-002 ft. Cushendall Tide, Table E. Difference of observed and calculated times of vanishing of diurnal tide at high water, expressed in lunar days. Age of lunar tide = 64 185 41™, No. | Difference. ! No. Difference.| No. Difference. days. days. : | days. 1 +1:32 10 | +052 | 19 | —058 2 —008 | 11 | —008 | 20 | —0-08 3 | —0-08 12 +052 || 21 | —0-68 A | +0:22. || 13. | —1:58 || 22 | —0:88 5 | +1-22 14 | +142 | 23 | —0-58 hope +1:22 || 15 —0-08 || 24 | —0-08 | 7 | 158 || 16 | +042 | 25 | —0-08 | 8 +0:92 || 17 —0-68 |- 26 | —0-08 | 9 | —0°78 18 +0°32 | Mean difference = +0-004 days. Cushendall Tide, Table F. Difference of observed and calculated times of vanishing of diurnal tide at low water, expressed in lunar days. Age of lunar tide =54 2h 45™, No. | Difference.| No. | Difference. No. | Difference. days. days. days. 1 +055 || 10 +0:05 || 19 +1°55 2 +0°55 11 —0°05 20 +1°85 3 +1:55 12 —0°45 21 —1°25 4 | 4055 | 13 | 4055 || 22 | +055 5 —0°85 14 —0°45 23 +0°55 6 —045 || 15 +1:05 24 +0°55 7 —105 || 16 —0-75 25 +0°55 8 —0°65 || 17 +0:55 26 —1-65 9 —1°85 || 18 —1:05 | Mean difference =0-000 days. Phil. Mag. S. 4. Vol. 11. No. 70. Feb. 1856. K 122 The Rev. S. Haughton on the Solar and Lunar From the preceding Tables, it is evident that the utmost. reliance may be placed in the values of the tide constants at this station. Section IX. Diurnal Tide at Donaghadee. From the Diurnal Tables, the solar and lunar diurnal tides at Donaghadee were calculated separately, and found to give the following results :— I. Diurnal tide at high water. . Maximum value of lunar tide for positive heights=0°42 ft. . Maximum value of lunar tide for negative heights =0°38 ft. . Maximum value of solar tide =0°28 ft. - Diurnal solitidal interval =11> 12™, . Age of lunar tide =64 54, oe OO Oe Il. Diurnal tide at low water. Maximum value of lunar tide for positive heights=0'39 ft. Maximum value of lunar tide for negative heights=0-42 ft. Maximum value of solar tide =0°28 ft. . Diurnal solitidal interval =115 12, . Age of lunar tide =54 2h, Adding the first two of each of the preceding, we : shins Range of lunar tide at high water =0°80 ft. - Range of lunar tide at low water =0°81 ft. Hence by equation (3), OUR 99 29 0:80 0:81 or, converting the are into time, M—in =o 7™ ; but since m is the moon’s hour-angle in Donaghadee time, at high water, and is 105 40™, we obtain, finally, inatae™. By equation (4), we have max. value of 2M sin 2u= V (0°80)? + (0°81)?=1-139 ft. ; from which we obtain cot (m—t,) = = cot (45° 21’) ; M=0°868 ft. Also, since the maximum value of the solar tide is 0°28 ft., we have, by equation 5, max. value of 2S sin 2o=0°56 ft., and Diurnal Tides of the Coasts of Ireland. 123 Combining these results, we have for the tide constants at pce . Lunitidal interval =75 33™, 2, Solitidal interval =115 12™. 3. Age of lunar tide at high water =64 5h, at low water =54 2h, 4. Lunar coefficient =0°868 ft. 5. Solar coefficient =0°’388 ft. 6. Ratio of solar to lunar coefficient, S or 7 =0°441. The theoretical tides at Donaghadee were constructed with the foregoing tide constants, and compared with the observed tides, with the following results. Donaghadee Tide, Table A. Positive heights at high water for sixteen and a half lunations, commencing 1850, September 294 54 51™, and ending 1851, December 224 224 24m, No. Observed. Calculated. Difference. || No. Observed. Caleulated,| Difference ft. ft. lea bi ft. ft. ft. 1 0-40 0-37. | +0-03 10 0-41 0°45 —0'04 2 0-26 0:30 —0-04 Il 0:60 0°52 +0:08 3 0-43 0-40 | +0-03 12 0:60 0°65 —0:05 4 0-47 045 | +002 || 13 | 058 059 | —0-01 5 0°57 0:59 —0-02 14 0-40 0-42 — 0°02 6 0°63 0:59 +0:04 15 0:37 0°38 —0-01 7 0:50 049 | +0-01 16 050 0:43 +0:07 8 0:30 0-32 +| —0-02 17 0-46 0:52 —0:06 | 9 | 083 | 0-85 | —0-02 | | Mean difference = —0-000 ft. Donaghadee Tide, Table B. Negative heights at high water for sixteen lunations, commencing 1850, September 2945451™, andending 1852, January5421512™, No. | Obse rved.|Calculated,| Difference./| No. | Observed. |Calculated.| Difference. | ft. ft. ft. ft. ft. ft. Ly .|,..039 0-28 +0-11 10 0-48 0:48 0:00 2 0°40 031 +0:09 11 0°60 0-58 +0-02 3 0°45 0:46 —0-01 12 0°50 0:56 —0:06 4 0°59 0-54 +0°05 13 0:47 0:48 —0°01 | 56 | 060 0:58 +0-02 14 0:32 0°33 —0-01 6 0°44 0:48 —0-04 15 0°34 0:29 +0:05 7 0-24 0°37 —0:13 16 0:46 0:38 +0:08 8 0-24 0-31 —0:07 17 0:56 0°55 +0°01 9 | 0°34 0-40 —0-06 } Mean difference = -+0-002 ft. K 2 124 Onthe Solar and Lunar Diurnal Tides of the Coasts of Ireland. Donaghadee Tide, Table C. Positive heights at Jow water for sixteen lunations, commencing 1850, October 12444, and ending 1851, December 22416 27™. | No. Observed. \Caleulated. | Difference.|| No. Observed. |Calculated. | Difference. | ft. ite ft. ft. ft. ft. 1 0:60 0-46 +0°14 9 0-44 0°59 —0°15 2 062 | 057 +0:05 10 0:55 0-64 —0:09 3. | O61 | 0°62 —0-01 11 0-48 0:57 —0-09 4 0:70 | 0-62 +0:08 12 0:36 0:52 —0:16 5 | 0:35 0:43 —0°08 13 0-46 0:39 +0:07 6 0:26 | 0:43 —0:17 14 0:60 0-42 +0:18 rf 0-42 | 0-41 +0-01 15 0:59 0-51 +0:08 8 | 057 0:50 +0:07 16 0-65 0-61 +0°04 Mean difference = —0°002 ft. Donaghadee Tide, Table D. Negative heights at low water for sixteen lunations, commencing 1850, October 12444, and ending 1851, December 22416527™. No. | Observed. Calculated. Difference.|| No. | Observed. |Calculated.| Difference. ft. ft. | ft. ft. ft. ft. 1 0:46 055 | —0-:09 9 0°66 0°68 —0:02 2 0:66 066 | 000 10 0:60 0-64 —0°04 3 0°55 0-67 | —0:12 1l 0°60 0-52 +0:08 4 0:60 0-54 +0:06 || 12 0°45 0:47 — 0:02 5 051 0°52 —0-01 13 0:40 0:42 — 0:02 6 0°35 0°42 | —0:07 14 0-60 0:47 +0:13 7 0:49 0:46 +0-05 15 0-72 0°62 +010 8 | 059 | 057 | +002 | 16 | 0-74 | 067 | +007 Mean difference = —0-006 ft. Donaghadee Tide, Table E. Difference of observed and calculated times of vanishing of diurnal tides at high water, expressed in lunar days. Age of lunar tide =64 54, No. | Difference.|| No. | Difference.!| No. | Difference. days. days. days. 1 —0°65 12 +1:05 23 +0:15 2 |} —1:25 || 13 +1°65 24 —2:-00 3 —3°65 || 14 — 1-20 25 +0:25 4 | —235 || 15 | 40-65 || 26 | +065 5 +1:20 16 —1:10 27 —1:35 6 0-00 17 +1:75 28 —0:05 7 +4:05 18 —0°35 29 —1:05 | 8 | +030 || 19 | +075 || 30 | —0-35 9 +0°95 20 — 1°45 31 +0°55 10 +0:15 21 +0°60 32 —0°60 ll +115 22 —0°25 33 +1:90 Mean difference = +-0°003 days. | Relation of Diamagnetic Polarity to Magnecrystallic Action. 125 Donaghadee Tide, Table F. Difference of observed and calculated times of vanishing of diurnal tides at low water, expressed in lunar days. Age of lunar tide =54 2h. No. | Difference.|| No. Difference.| No. Difference.| days. | days. days. ] +0:10 12 |} —1:10 23 —0°35 | 2 | 41-00 | 13 || —0-95 | 24 | 40-85 | 3 —0°45 14 —0:05 25 —0-20 ity 3. +1-00 | 15 —0°-40 26 +1:°75 | 5 | +020 || 16 || —0-90 | 27 | +075 6 | —280 | 17 || —o10 | 28 | —1-05 | 7 | —065 |} 18 +0:20 29 +1:60 8 | +1:30 || 19 —0°55 30 +1:30 9 | +085 | 20 || 41-15 | 31 | 40-75 10 +110 21 || —0-65 32 —1:35 | Il | —1-45 22 |) 41:45 33 —2-00 Mean difference = +0-010 days. | The agreement of the observed and calculated diurnal tides shown in the preceding Tables is excellent. [To be continued. | XV. On the relation of Diamagnetic Polarity to Magnecrystallic Action. By Joun Tyna, F.R.S. &c.* N a communication presented to the Royal Society some weeks ago, the fact of diamagnetic polarity was established in the ease of insulators, among which phosphorus, sulphur, calcareous spar, statuary marble, heavy glass, nitre, and wax were comprised. The demonstration was also extended to distilled water and other liquids ; and thus the conditions proposed by the opponents of diamagnetic polarity for its rigorous demonstration were fulfilled. The importance of the principle is demonstrated by the fruit- fulness of its consequences ; for by it we obtain a clear insight of phenomena which, without it, would remain standing enigmas in science, being connected by no known tie with the ordinary laws of mechanics. Many of the phenomena of magnecrystallic action are of this paradoxical character. For the sake of those who see no clear connexion between these phenomena and the other effects of magnetism, as well as for the sake of complete- ness, I will here endeavour to indicate in a simple manner, and from my own point of view, the bearing of the question of polarity upon that of magnecrystallic action. I will commence with the elementary phenomena, and select for illustration as I proceed, * Communicated by the Author. 126 Prof, Tyndall on the relation of Diamagnetic Polarity eases of real difficulty which have been actually encountered by those who have worked experimentally at the subject. To liberate the thoughts from all effects except those which are purely magnecrystallic, we will for the present operate with spheres. Let a sphere of carbonate of lime be suspended before the pole §, fig. 1, of an electro-magnet, so that the axis of the erystal shall be hori- zontal. Let the line Fig. l. ab mark any position of the axis inclined tothe direction of the foreeemanating from S ; and let the dotted line de make an equal angle with the direc- tion of the force at the other side. Asthe sphere is diamagnetic, the face of it which is turned towards 8 will be hostile to S, while that turned from S will be friendly to 8, according to the principles established in the paper above referred to; and, if the sphere were homoge- neous, the tendency to set ab at right angles to the direction of the force would be exactly neutralized by the tendency to set cd in the same position: the sphere would consequently stand still. But the case is otherwise if the intensity of diamagnetization along ab be greater than along ed, which I have elsewhere shown to be the fact*. Ifwe suppose the sphere to vanish, with the excep- tion of two thin needles taken along the lines mentioned, the hostile pole at a will be stronger than that at c, and the friendly pole at 4 will be stronger than that at d; hence the ends a and 6 being acted upon by a mechanical couple of superior power, the line ab will recede from its inelined position, and finally set itself at right angles to the direction of the force. Whatever be the inclination of the line ad to the magnetie axis, this superiority will belong to its couple; it is therefore manifest that the entire sphere will turn in the manner here indicated, and finally set with the axis of the crystal equatorial, which is the result esta- blished by experiment. For the diamagnetic calcium, contained in this crystal, let the magnetic element, iron, be substituted. Each molecule of the crystal becomes thereby magnetic; we have carbonate of iron in place of carbonate of lime ; and the line which, in the latter sub- stance isthat of maximum repulsion, is that of maximum attraction inthe former. This, I think, is one of the most suggestive points t * Phil. Mag. S. 4. vol. ii. p. 176. + For its bearmg upon the question of a magnetic medium see Phil. Mag. vol. ix. p. 208. to Magnecrystallic Action. 127 that researches in magnecrystallic action have established, namely, that the self-same arrangement of particles influences the para- magnetic and diamagnetic forces in the self-same way, intensifying . both in the same direction. Let us suppose, then, that the sphere of carbonate Fig. 2. of iron is suspended as in fig. 2, the line ab being the axis of the crystal. I have already shown that this line is that in which the magnetic induction is most in- tense*. Comparing, as before, the lines ab and cd, the friendly pole ais stronger than e, and the hostile pole } is stronger than d; aresidual “ couple” therefore acts upor aé in the direction indicated by the arrows, which will finally set this line parallel to the direction of the force. This is also the result which experiment exhibits. We will now proceed to apply the principle of polarity to some of the more complicated forms of magnecrystallic action. Some highly paradoxical effects were adduced by Mr. Faraday as illus- trative of his earlier impressions regarding this question, and I cannot bring the subject in a clearer manner before the reader than by quoting Mr. Faraday’s own description of the phzno- mena referred to. Here it follows :— “ Another very striking series of proofs that the effect is not due to attraction or repulsion was obtained in the following manner. A skein of fifteen filaments of cocoon silk, about 14 inches long, was made fast above, and then a weight of an ounce or more hung to the lower end; the middle of this skein was about the middle of the magnetic field of the electro-magnet, and the square weight below rested against the side of a block of wood so as to give a steady silken vertical axis without swing or revolution. A small strip of card, about half an inch long and the tenth of an inch broad, was fastened across the middle of this axis by cement ; and then a small prismatic crystal of sulphate of iron 0°3 of an inch long and 0°1 in thickness, was attached to the card, so that the length and also the magnecrystallic axis were in the horizontal plane; all the length was on one side of the silken axes, so that as the erystal swung round, the length was radius to the circle described, and the magnecrystallic axis parallel to the tangent. “ When the crystal was made to stand between the flat-faced poles, the moment the magnet was excited it moved, tending to * Phil. Mag. S. 4. vol. ii. p. 177. 128 Prof. Tyndall on the relation of Diamagnetic Polarity stand with its length equatorial, or its magnecrystallic axis parallel to the lines of force. When one pole was removed and the experi- ment repeated, the same effect took place, but not so strongly as before ; finally, when the pole was brought as near to the crystal as it could be without touching it, the same result occurred, and with more strength than in the last case. In the two latter experiments, therefore, the crystal of sulphate of iron, though a magnetic body, and strongly attracted by such a magnet as that used, actually receded from the pole of the magnet under the influence of the magnecrystallic condition. “Tf the pole S* be removed and that marked N be retained for action on the crystal, then the latter approaches the pole urged by both the magnetic and magnecrystallic forces; but if the crystal be revolved 90° to the left, or 180° to the right, round the silken axis, so as to come into the contrary or oppo- site position, then this pole repels or rather causes the removal to a distance of the crystal, just as the former did. The experi- ment requires care, and I find that conical poles are not good; but with attention I could obtain the results with the utmost readiness. “The sulphate of iron was then replaced by a crystalline plate of bismuth, placed, as before, on one side of the silk suspender, and with its magnecrystallic axis horizontal+. Making the position the same as that which the crystal had in relation to the N pole in the former experiment, so that to place its axis parallel to the lines of magnetic force it must approach this magnetic pole, and then throwing the magnet into an active state, the bismuth moved accordingly and did approach the pole, against its dia- magnetic tendency, but under the influence of the magnecry- stallic force. “ Hence a proof that neither attraction nor repulsion governs therseti fay sce This force, then, is distinct in its character and effects from the magnetic and diamagnetic forms of force.” These experiments present grave mechanical difficulties, and are quite sufficient to justify the conclusion drawn from them, namely, that the force which produces them 1s neither attractive nor repulsive. We will now endeavour to apply the idea of a force which is both attractive and repulsive, or in other words of a polar force, to the solution of the difficulty. * The figures will be given and explained further on. + It will be borne in mind that Myr. Faraday calls the line in a crystal which sets from pole to pole, the magnecrystallic axis of the crystal, whether the latter is paramagnetic or diamagnetic. in bodies of the former class, however, the “‘ axis”’ sets from pole to pole because the attraction along it is a maximum; while in bodies of the latter class, the ‘‘axis’’ sets from pole to pole because the repulsion along the line perpendicular to it is a maximum. to Magnecrystallic Action. 129 For the sake of disencumbering the mind of all considerations save those which belong to pure magnecrystallic action, we will suppose, as before, the bodies experimented with to be spherical. Let the dot at 2, fig. 3, be Fig. 3. the intersection of the silken axes with Mr. Faraday’s strip of card; and on the end of the strip, let the sphere of sulphate of iron be placed with its mag- S necrystallic axis ab at night angles to the length of the strip. This line, as I have already shown*, is that of most in- tense magnetization through the crystals. The forces acting on the sphere in its present position are exactly similar to those acting upon the carbonate of iron in fig. 2. A residual “couple” will apply itself at the extremities of ab, as indicated by the arrows, and would, if the sphere were free to turn round its centre of gravity, set the line ad parallel to the magnetic axis. But the sphere is here rigidly connected with a lever moveable round its own axis of suspension, and it is easy to state the mechanical result that must follow from this arrangement. ‘To obtain the moments of the two forces acting upon a and b, we have to multiply each of them by its distance from the axis z. In front of a flat pole such as that made use of by Mr. Faraday in these experiments, the force diminishes very slowly as we recede from the pole, so that the attraction of a does not so far exceed the repulsion of } as to prevent the pro- duct of the latter into xz from exceeding that of the former into xy, and consequently the paramagnetic sphere must recede from the pole. In his next experiment, Mr. Fig. 4. Faraday removed the pole S and allowed the pole N to act upon the crystal as in fig. 4. In this case it will be seen that the end nearest the pole, and therefore the most strongly attracted, is also at the greatest distance from the axis of rotation. | Hence the sphere must approach the pole, as it does in the experiment. When the strip of card is revolved 90°, we have the state of things shown in fig. 5; and when it is revolved 180°, we have * Phil. Mag. S. 4. vol. ii. p. 178. ® 130 Prof. Tyndall on the relation of Diamagnetic Polarity the state of things shown in fig. 6. It is manifest, for the mechanical reasons already assigned, that the erystal, in both these cases, must recede from the pole. Substituting for the sphere of sulphate of iron a sphere of bismuth with its magnecrystallic axis cd, fig. 7, perpendi- cular to the strip of card, the bismuth is found to approach the Fig. 7. pole when the magnet is excited. The line ab perpendicular to that named the magnecrystallic axis, has been shown by Mr. Fa- raday to be that of greatest dia- magnetic intensity ; the mass is therefore under the influence of 4 forces precisely similar to those acting on the carbonate of lime in fig. 1. A residual couple, as denoted by the arrows, will act at the extremities of the line ad. The absolute repulsion of a in the field of force here assumed, does not differ much from the absolute attraction of 6; but the latter force acts at the end of a much longer lever, and conse- quently the sphere is drawn towards the excited pole. I cannot help remarking here upon the severe faithfulness with which these results are recorded, and on the inestimable value of such records to scientific progress. The key to their solution being once found, the investigator may proceed confidently to the applica- tion of his principles, without fear of check or perplexity arising from the imperfection of his data. In all these cases we have assumed that the magnetic force diminishes slowly as we recede from the pole, for this is essential to the production of the effects. The exact expression of the con- dition is, that the advantage due to the proximity of the part of the mass nearest the pole, must be less than that arising from the to Magnecrystallic Action. 131 greater leverage possessed by the force acting on the more distant parts. When the shape of the poles is such that the diminution of the force with the increase of distance is too speedy for the above condition to be fulfilled, the phenomena no longer exhibit themselves. It is plain that the diminution of the force as we recede from a pointed pole must be more speedy than when we recede from a magnetized surface, and hence it is that Mr. Fa- raday finds that “conical poles are not good.” It is also essen- tial that the length of the lever which supports the magnecry- stallic body shall bear a sensible ratio to the distance between the two points of application of the magnetic force. If the lever be long, recession will take place in cases where, with a shorter lever, approach would be observed. It is well known that a piece of soft iron is attracted most strongly by the angles and corners of a magnet, and hence it is inferred that the magnetic force emanating from these edges and corners is more intense than that issuing from the central parts of the polar surfaces. Such experiments, however, when nar- rowly criticised, do not justify the inference drawn from them. They simply show that the difference between attraction and repulsion, on which the final attraction depends, is greater at the edges than elsewhere; but they do not enable us to infer the absolute strength of either the attraction or the repulsion, or in other words, of the force of magnetization. The fact really is, that while the attraction of the mass is nearly absent in the central portion of a magnetic field bounded by two flat poles, the magnetization is really stronger there than between the edges. This is proved by the following experiment :—I suspended a cube of crystallized bismuth from a fibre of cocoon silk, and when the magnet was excited, the cube set its planes of prin- cipal cleavage equatorial. When drawn aside from this position and liberated, it oscillated round it. Between the upper edges of the moveable poles the number of oscillations performed in a minute was seventy-six ; in the centre of the field the number performed was eighty-eight, and between the lower edges eighty. A cube of magnetic slate, similarly suspended, oscillated in the centre of the field forty-nine times, and between the edges only forty times, in fifteen seconds. In the former position there was no sensible tendency of the cube to move towards either pole; but in the latter position, though the magnetization was considerably less intense, the cube was with difficulty prevented from moving up to one or the other of the edges. 'The reason of all this manifestly is, that while the forces in the centre of the field nearly neutralize each other as regards the ¢ranslation of the mass, they are effect- ive in producing its oscillation; while between the edges, though the absolute forces acting on the north and south poles of the 132 Prof. Tyndall on the relation of Diamagnetic Polarity excited substances are less intense, the difference of these forces, owing to the speedier diminution of the force with the distance, is greater than in the centre of the field. It is therefore an error to infer, that, because the attraction of the mass is greater at the edges and corners than in the centre of the field, the mag- netizing force of the former must therefore be more intense than that of the latter*. There is another interesting and delicate experiment of Mr. Faraday’s to which I am anxious to apply the principle of dia- magnetic polarity: the experiment was made with a view of proving that “the magnecrystallic force is a force acting at a distance.” “The crystal,” writes Mr. Faraday, “is moved by the magnet at a distance, and the crystal can also move the mag- net at a distance. To produce the latter result, I converted a steel bodkin, 3 inches long, into a magnet, and then suspended it vertically by a cocoon filament from a small horizontal rod, which again was suspended by its centre and another length of cocoon filament, from a fixed point of support. In this manner the bodkin was free to move on its own axis, and could also describe a circle about 14 inch in diameter; and the latter motion was not hindered by any tendency of the needle to point under the earth’s influence, because it could take any position in the circle and yet remain parallel to itself. “ When a crystal of bismuth was fixed on a support with the magnecrystallic axis in a horizontal direction, it could be placed near the lower pole of the magnet in any position; and bemg then left for two or three hours, or until by repeated examination the magnetic pole was found to be stationary, the place of the latter could be examined, and the degree and direction in which it was affected by the bismuth ascertained. .... The effect pro- duced was small; but the result was, that if the direction of the magnecrystallic axis made an angle of 10°, 20°, or 30° with the line from the magnetic pole to the middle of the bismuth crystal, then the pole followed it, tending to bring the two lines into parallelism ; and this it did whichever end of the magnecrystallic axis was towards the pole, or whichever side it was inclined to. By moving the bismuth at successive times, the deviation of the magnetic pole could be carried up to 60°. The crystal, there- fore, is able to react upon the magnet at a distance. But though it thus takes up the character of a force acting at a distance, still it is due to that power of the particles which makes them cohere in regular order, and gives the mass its crystalline aggregation ; which we call at other times the attraction of aggregation, and so often speak of as acting at insensible distances.” * Some important consequences resulting from this experiment are in- tended for a future communication. to Magnecrystallic Action. 133 The disposition of this important experiment will be manifest from fig. 8, where cd is the magnecrystallic axis of a sphere of bismuth, or the line in which the ? diamagnetic induction is least in- Fig. 8. tense; and s'n' the direction of the principal cleavage, or that of most intense diamagnetization. Let n be the point of the bodkin, say its north pole, the crystal will be excited by the influence of this pole, and the resultant action will be the same as if it were exclu- sively “ diamagnetized” along the line s‘x’. At the end nearest to the pole of the bodkin a repelled pole x will be excited in the bismuth ; at the most distant end an attracted pole s! will be ex- cited. Let the repulsive force tending to separate n from 7! be represented by the line np, and let the attraction exerted between s' and n be represented by the line ng; the arrange- ment is such that the force of s! acts more nearly in the direction of the tangent than that of n’; the latter may be decomposed into two, one acting along the circle and the other across it: the latter component exerts a pressure against the axis of suspension ; the former only is effective in causing the pole m to move; so that the whole, or nearly the whole, of the attraction has to compete with a comparatively small component of the repulsion. The former therefore preponderates, and the pole x approaches the crystal. It is manifest that as the angle which the line from n to the centre of the crystal makes with the magnecrystallic axis, increases, the component of repulsion which acts in the direc. tion of a tangent to the curve, augments also; and that at a certain point this component must become preponderant. Beyond an angle of 30° it is to be presumed that Mr. Faraday did not obtain the effect. Removing the crystal, and placing a small magnet in the position of the line s! n!, with its poles arranged as in the figure, the same phenomena would be produced *, As finally illustrative of the sufficiency of the principle of polarity to explain the most complicated phenomena of magne- erystallic action, let us turn to the consideration of those curious effects of rotation first observed by M. Pliicker, and which I * As there are no measurements given of the distances between the crystal and the pole, it is of course impossible to do more than indicate generally the theoretic solution of the experiment. pipes rd i 134 Prof. Tyndall on the relation of Diamagnetic Polarity have illustrated by thirty-seven cases in the Bakerian Lecture for 1855. The effects, it will be remembered, consisted of the turning of elongated paramagnetic bodies suspended between pointed poles from the axial to the equatorial position, and of elongated diamagnetic bodies, from the equatorial to the axial position, when the distance between the suspended body and the influencing poles was augmented. I know this to be a subject of considerable difficulty to many, and I therefore claim the indulgence of those who have paid more than ordinary attention to it, if in my explanation I should appear to presume too far on the reader’s want of acquaintance with the question. Let us then suppose an elongated crystal of tourmaline, stauro- lite, ferrocyanide of potassium, or beryl, to be suspended be- tween the conical poles N, 8, fig.9, of an electro-magnet ; sup- posing the position between the poles to be the oblique one shown in the figure, let us inquire what are the forces acting Fig. 9. es M le-F upon the crystal in this position. In the case of all paramag- netic crystals which exhibit the phenomenon of rotation, it will be borne in mind that the line of most intense magnetization is at right angles to the length of the crystal. Let sa be any transverse line near the end of the crystal ; fixing our attention for _ the present on the action of the pole N, we find that a friendly pole is excited at s and a hostile pole at n: let us suppose s and n to be the points of application of the polar force, and, for the sake of simplicity, let us assume the distances from the point of the pole N to s and from s to n, to be equal to one another. We will further suppose the action of the pole to be that of a magnetic point, to which, in reality, it approxi- mates ; then, inasmuch as the quantities of north and south mag- netism are equal, we have simply to apply the law of inverse squares to find the difference between the two forces. Calling that acting on s unity, that acting on will be 4. Opposed to this difference of the absolute forces is the difference of their moments of rotation; the force acting on z is applied at a greater distance from the axis of rotation, but it is manifest that to counterbalance the advantage enjoyed by s, on account to Magnecrystallic Action. 135 of its greater proximity, the distance zz would require to be four times that of zy. Taking the figure as the correct sketch of the poles and crystal, it is plain that this condition is not fulfilled, and that hence the end of the crystal will be drawn towards the pole N. What we have said of the pole N is equally applicable to the pole 8, so that such a crystal suspended be- tween two such poles, in the manner here indicated, will set its length along the line which unites them. While the crystal retains the position which it occupied in fig. 9, let the poles be removed further apart, say to ten times their former distance. The ratio of the two forces acting on the two points of application s and 7 will be now as the square of 11 to the square of 10, or as 6:5 nearly. Taking fig. 10, as in the former case, to be the exact sketch of the crystal, it is Fig. LO. AS cmd manifest that the ratio of wz to wy is greater than that of 6 to 5; the advantage, on account of greater leverage, possessed by the force acting on 2 is therefore greater than that which greater proximity gives to s, and the consequence is that the crystal will recede from the pole, and its position of rest between two poles placed at this distance apart will be at right angles to the line which joins them. It is needless for me to go over the reasoning in the case of a diamagnetic body whose line of strongest diamagnetization is perpendicular to its length. Re- versing the direction of the arrows in -the last two figures, we should have the graphic representation of the forces acting upon such a body; and a precisely analogous mode of reasoning would lead us to the conclusion, that when the polar points are near the crystal, the latter will be driven towards the equatorial position, while where they are distant, the crystal will be drawn into the axial position. In this way the law of action laid down empiri- eally in the Bakerian Lecture for 1855 is deduced @ priori from the polar character of both the magnetic and diamagnetic forces. The most complicated effects of magnecrystallic action are thus reduced to mechanical problems of extreme simplicity; and, inasmuch as these actions are perfectly inexplicable except on the assumption of diamagnetic polarity, they add their evidence 136 Relation of Diamagnetic Polarity to Magnecrystallic Action. in favour of this polarity to that already furnished in such abundance. Perhaps as remarkable an illustration as could be chosen of the apparently perplexing character of certain magnetic pheno- mena, but of their real simplicity when the exact nature of the force producing them is understood, is furnished by the follow- ing experiment. I took a quantity of pure bismuth powder and squeezed it between two clean copper plates until the powder became a compact mass. A fragment of the mass suspended before the pointed pole of a magnet was forcibly repelled; and when suspended in the magnetic field with the direction of pressure horizontal, in accordance with results already ‘sufli- ciently well known, it set its line of pressure equatorial. A second quantity of the bismuth powder was taken, and with it was mixed a quantity of powdered carbonate of iron, amount- ing to ;5,ths per cent. of the whole; the mass was still strongly diamagnetic, but the line of compression, instead of setting equatorial, as in the former instance, set decidedly axial. A quantity of the mixed powder was next taken, in which the magnetic constituents amounted to 1 per cent. The mass was still diamagnetic, but the line of compression set axial; it did so when the influence of exterior form was quite neutralized, so that the effect must be referred solely to the compression of the mass. With 2 per cent. of carbonate of iron powder the mass was magnetic, and set with increased energy its line of compression axial; with 4 per cent. of carbonate of iron the same effect was produced in a still more exalted degree. Now, why should the addition of a quantity of carbonate of iron powder, which is altogether insufficient to convert the mass from a diamagnetic to a paramagnetic one, be able to overturn the tendency of the diamagnetic body to set its line of com- pression equatorial? The question is puzzling at first sight, but the difficulty vanishes on reflection. The repulsion of the mass of bismuth, suspended before a pointed pole, depends upon the general capacity of the mass for diamagnetic induction, while its position as a magnecrystal between the flat poles de- pends on the difference between its capacities in two different directions. The diamagnetic capacity of the mass may be very great, while its capacity in different directions may be nearly alike, or quite so: the former, in the case before us, came into play before the pointed pole; but between the flat poles, where the directive, and not the translative energy is great, the car- bonate of iron powder, whose directive power, when compressed, far exceeds that of bismuth, determined the position of the body. In this simple way a numberof perplexing results ob- tained with bodies formed of a mixture of paramagnetic and M. Schonbein on Ozone and Ozonic Actions in Mushrooms. 137 diamagnetic constituents, is capable of satisfactory explana- tion. Finally, inasmuch as the set of the mass in tie magnetic field depends upon the difference of its excitement in different direc- tions, it will follow that any circumstance which affects all directions of a magnecrystallic mass in the same degree will not disturb the differential action upon which its deportment de- pends. This seems to me to be the explanation of the results recently obtained by Mr. Faraday with such remarkable uni- formity, namely, that, no matter what the medium may be in which the magnecrystallic body is immersed, whether air or liquid, paramagnetic or diamagnetic, it requires, in all cases, the same amount of force to turn it from the position which it takes up in virtue of its structure. I have thus dwelt upon instances of magnecrystallic action which have revealed themselves in actual practice, as affording the best examples for the application of the knowledge which the demonstration of the polarity of the diamagnetic force places in our possession ; and [ believe it has been shown that these phzenomena, which were in the highest degree paradoxical when first announced, are deducible with as much ease and certainty _ from the action of polar forces, as the precession of the equi- noxes is from the force of gravitation. The whole domain of magnecrystallic action is thus transferred from a region of mechanical enigmas to one in which our knowledge is as clear and sure as it is regarding the most elementary phenomena of magnetic action. Royal Institution, Dec. 1855. XVI. On Ozone and Ozonic Actions in Mushrooms. By M. Scuénsein*, My pear Farapay, btsi Age know that I hold oxygen, both in its free and bound state, to be capable of existing im two allotropic modi- fications,—in the ozonic or active, and the ordinary or inactive condition. All the oxy-compounds yielding common oxygen at a “yaised temperature I consider to contain ozonized oxygen; and I am further inclined to believe that the disengagement of common oxygen from those compounds depends upon the transforma- tion of the ozonized oxygen into the inactive one, or, to de- note that allotropic change, of O into O. Nowa general fact is this: that the oxygen thus set free always contains traces of O * Communicated by Professor Faraday. Phil, Mag, 8, 4, Vol, 11, No, 70, Feb, 1856, L 1388 M.Schénbein on Ozone and Ozonic Actions in Mushrooms. more or less, according to the degree of temperature at which the oxygen happens to be disengaged from those compounds, The lower that degree, the larger the quantity of © mixed with O; though I must not omit to state, that in all cases that quan- tity happens to be exceedingly small in comparison to that of O obtained at the same time. The best means of ascertaining the presence of O is the alcoholic solution of guaiacum recently pre- pared. You know that O does not in the least change the colour of that resiniferous liquid, whilst freeO orPbO + O, &c. have thepower of colouring it deep blue. The blue matter is, as I think I have proved it, nothing but guaiacum +0. Now if you heat the purest oxide of gold, platinum, silver, mercury, the peroxides of manganese, lead, &c., in fact any substance yielding oxygen, within a small glass tube into which you had previously in- troduced a bit of filtering-paper impregnated with the said guaiacum solution, you will see that bit of paper turn blue as soon as the disengagement of oxygen begins to take place; and all the circumstances being the same, you will further perceive that the paper is coloured most deeply and rapidly by the oxygen eliminated from that oxy-compound which requires the lowest temperature for yielding part or the whole of its oxygen. Thus the oxygen disengaged from the oxides of gold, pla- tinum and silver, acts more energetically upon the guaiacum solution than does the oxygen eliminated from the oxide of mercury, the peroxide of manganese, &c. I trust these results will be obtained in the Royal Institution just as well as I get them in the laboratory of Bale, or else my discovery will be a very poor thing. As there cannot, I should think, be any doubt that all the oxygen, contained, for instance, in the oxide of silver previously to that compound being decomposed by heat, exists but in one state, be that state what it may, how then does it happen, we may ask, that at the same time two different sorts of oxygen, O ond O, are disengaged from the compound named ? The answer to this question seems to me to be, that one of the two kinds of oxygen eliminated must be engendered at the ex- pense of the other; or to speak more correctly, that during the act of the elimination of oxygen from the oxide of silver, part of that oxygen suffers a change of condition. Now as the oxides of gold, silver, &c. enjoy the power of colouring blue the guaiacum solution, just as free O does, I draw from that fact the conclusion, that the condition of the oxygen contained in the oxides of gold, silver, &c. is the ozonic one; and further infer, that by far the greatest portion of that O, under the in- fluence of heat, is transformed into O. Why the whole of the M. Schonbein on Ozone and Ozonic Actions in Mushrooms. 189 oxygen disengaged from those oxides does not happen to be O I certainly cannot tell, but I think that the very fact of the mixed nature of the oxygen in question is, in a theoretical point of view, highly important, and speaks in favour of my notions rather than against them. Although I have already heavily taxed your patience, I am afraid I cannot yet release you from further listenmg to my philosophical talkings, for I have still to speak of a subject that has of late deeply excited my scientific curiosity, and taken up all my leisure time. But to give you an idea of what I have been doing these last two months, I must be allowed prefacing a little. You know that I entertain a sort of innate dislike to touch anything in the slightest way connected with organic chemistry, knowing too well the difficulty of the subject and the weakness of my power to grapple with it; but in spite of this well-grounded disinclination, I have of late, and, as it were, by mere chance, been carried into the midst of that field, upon the intricacies and depths of which I have been used all my life to look with feelings of unbounded respect and even awe. The picking up of a mushroon has led to that very strange aberration of mine, and you willask how such a trifling occurrence could do that. The matter stands thus: what the botanists tell me to be called “ Boletus luridus,’ with some other sorts of mushroom, have the remarkable property of turning rapidly blue when their head and stem happen to be broken and exposed to the action of the atmospheric air. On one of my ramblings I found a spe- cimen of the said Boletus, perceived the change of colour alluded to, and being struck with the curious phenomenon, took the bold resolution to ascertain, if possible, its proximate cause. I carried home the part, set to work, and found more than I looked for, which luckily enough happens now and then. Being, by the short space allotted even to the longest letter, prevented from entering into the details of the subject, I confine myself to stating the principal results obtained from my mush- room researches. Boletus luridus contains a colourless principle, easily soluble in alcohol ; and in its relations to oxygen, bearing the closest resemblance to guaiacum, as appears from the fact, that all the oxidizing agents which have the power of bluing the alcoholic solution of guaiacum, also enjoy the property of colouring blue the alcoholic solution of our mushroom principle ; and all the deoxidizing substances by which the blue solution of guaiacum is decolorized also discharge the colour of the blued solution of the Boletus matter. From this fact and others, I infer that this mushroom principle, like guaiacum, is capable of combining with O, and is not affected by O. Now the occur- rence of a matter so closely related to guaiacum in a mush- L2 ~ 140 M. Schodnbein on Ozone and Ozonie Actions in Mushrooms. room isa fact pretty enough of itself, but as to scientific import- ance far inferior to what I am going to tell you. The fact that the resinous Boletus principle, after having been removed from the mushroom (by the means of alcohol), is not able to colour itself spontaneously in the atmospheric air, whilst it seems to have that power so long as it happens to be deposited in the parenchyma of the Boletus, led me to suspect that there exists in the Boletus luridus, besides the guaiacum-like sub- stance, another matter, endowed with the property of exalting the chemical power of common oxygen, and causing that element in its O condition to associate itself to the resinous principle of the mushroom. The conjecture was correct ; for I found that in the juice obtained by pressure from a number of mushrooms belonging to the genera Boletus and Agaricus, and notably from Agaricus sanguineus (upon which I principally worked), an organic matter is contained which enjoys the remarkable power of transforming O into O, and forming with the latter a compound from which 0 may easily be transferred to a number of oxidable matters, both of an inorganic and organic nature; and I must not omit to state, that the peculiar agaricus matter, after having been deprived of its 0, may be charged with it again by passing through its solution a current oO of air. The easiest way of ascertaining the presence of O in the said agaricus juice, is to mix that liquid with an alcoholic solu- tion of guaiacum, or the resinous matter of the Boletus luridus. If the juice happens to be deprived of O, the resiniferous solu- tions will not be coloured blue; but if it contains 0, the solu- tions will assume a blue colour, just as if they were treated with peroxide of lead, permanganic acid, hyponitric acid, &e. From the facts stated, it appears that the organic matter in question is a true carrier of active oxygen, and therefore, when charged with it, an oxidizing agent. Indeed, that matter may in many respects be compared to NO?, which, as is well known, enjoys to an ex- traordinary extent the power of instantaneously transforming O into O, and forming a compound (NO2+ 20) with that O, from which the latter may easily be transferred to a multitude of oxi- dable matters. Now in a physiological point of view, the exist- ence of such an organic substance is certainly an important fact, and seems to confirm an old opinion of mine, according to which the oxidizing effects of the atmospheric oxygen (of itself inactive) produced upon organic bodies, such as blood, &c., are brought about by means of substances having the power both of exciting and carrying oxygen. Before dropping this subject, I must not omit to mention a Analysis of the Meteorites of Mezé-madaras in Transylvania. 141 fact or two more. The peculiar matter contained in the juice of the Agaricus sanguineus, &e., and charged with O, gives up that oxygen to guaiacum, and the latter transfers it to the resinous matter of the Boletus lwridus ; thus the different organic matters capable of uniting with O as such, exhibit different affini- ties for that oxygen, a fact not without physiological importance. Another fact worthy of remark, is the facility with which the nature of our agaricus matter may be changed. On heating the aqueous solution which has the power of deeply bluing the guaiacum solution to the boiling-point, it not only loses the property, but also the capacity of again becoming an oxidizing agent, 2. e. carrier of oxygen, however long it may be kept in contact with atmospheric air. I am very sorry to be prevented from entering more fully into the details of the subject, but from the little I have said about it you may easily understand why this mushroom affair has of late so much engaged my attention..... Yours most faithfully, Bale, Noy. 30, 1855. C. F. Scuonszrn. XVII. Analysis of the Meteorites of Mezi-madaras in Transyl- vania. By Professor WOuLER and Dr. ATK1nson*., We have analysed the meteorites which fell at Mezé-madaras in Transylvania on the 24th of September, 1852. Their external appearance afforded sufficient presumption that they were a mixture of several minerals, and this has been confirmed by analysis. Metallic iron, containing 7:4 per cent. of nickel and 0°25 per cent. of cobalt, forms a chief constituent. The quantity of iron varies in different parts of the specimen, but averages 19°60 per cent. of the entire weight. It was not possible to extract it completely from the powdered meteorite by means of the magnet. We calculated its quantity from the volume of hydrogen evolved when a weighed portion of the meteorite was treated with dilute sulphuric acid. Like all meteoric iron, this also contains phos- phorus, the amount of which could not, however, be determined without employing much larger quantities of material. It is not passive, but precipitates copper. Iron pyrites is a second constituent. It is here and there perceptible to the naked eye; its presence was also shown b the sulphuretted hydrogen, on treating the meteorite with hy- drochloric acid. We did not consider it essential to determine its quantity, since it evidently occurs very unequally mixed. Graphite, to the amount of 0°25 per cent.,is a third constituent. * Communicated by Dr. Atkinson. 142 Prof. Wohler and Dr. Atkinson’s Analysis of the It was seen in brilliant shining lamelle on boiling out the me- teorites with hydrochloric acid. The chief mass consists of two kinds of silicates, of which one is decomposed and gelatinized by hydrochloric acid, and the other is not decomposed. A microscopic examination showed that most of the minerals which occur in rounded particles on the dark mass of the me- teorite are silicates undecomposable by acids, while the mass of the stone is chiefly made up of decomposable constituents. Ex- clusive of the determination of the quantity of hydrogen evolved on treating the meteorite with acid, three kinds of analysis were made. One by fusing the meteorite with carbonate of soda, from which the quantity of silica was found to be 41°62 per cent. A second was made with hydrofluoric acid, in which the quan- tity of silica estimated from the difference was 43:94 per cent. This excess of 2°32 of silica is explained partly from the unequal mixedness of the meteorite, partly from the unavoidable loss in so many constituents, which of course fell on the difference, and partly from the phosphorus, sulphur, and oxide of chromium, the quantities of which were too small to be determined with any degree of accuracy. In this manner, by the usual methods, the meteorites were found to contain in 100 parts the following constituents :— Metallic iron . . . 18:10 INICKOl is cc. ne nat ee aa os RGOMERE a ore itce: ive ey oe Grapmite 45-50.) ree Magnesia . . . . 28°83 Protoxide of iron . . 4°61 Protoxideofmanganese 0°28 SNM. we hye ee Tt te ee eee | tO 0 1 eas age ot aac Re 9 POG we erat P.O Sulphur : Phosphorus. . Oxide of chromium Aa Gi Silica 100-00 An experiment was made to separate the two kinds of silicates. The finely-powdered meteorite was heated for a long time with strong hydrochloric acid. The residue was well washed out, and boiled repeatedly with carbonate of soda. The insoluble residue amounted to 30°48 per cent. (In a second experiment, where the mass was not boiled so long with carbonate of soda, 36 per cent. was obtained.) Meteorites of Mezé-madaras in Transylvania ~ 143 These 30:48 parts of undecomposed residue gave, when ana- lysed with hydrofluoric acid,— In 100 parts. Magnesia . . . . . 4600 15:29 Protoxide ofiron. . . 4643 15°25 WME vasa oie he tae ee 3°05 Ajomma~-.> ./. .,. O'D64 1°85 Maga e.g Ome 1:91 Potassa Preteens eaten Cree 1:13 Geapne see. es | ROU 0°82 Grn O iste abel eel Ces Lake alanoe Ae Lend St Sy a a Les 60°70 30°48 100-00 After subtracting the 19-6 per cent. iron, there remains 50°92 per cent. of silicates soluble in hydrochloric acid, and consisting of— In 100 parts. Marnésia’).) 3) %80s: 19°70 37°64 Alona 000i.) 98D 86 5:08 ine! te se ai eB ZO 1:70 Sitar sR Hose alee SER 3°44 POtassais & t4>) Sc) we od nee ghOsLDO 0:30 Silisge Paice 2, |Y8S6°386 51°84 50:°920 100:00 From these results, it does not appear to us that any conclu- sion can be drawn as to the composition of the meteorites. The more so, when we consider that even the insoluble part may con- tain compounds which are partially decomposed by the continued action of the acid, and afterwards by the alkali. If the quan- tities of oxygen in the magnesia and iron, the two predominating bases in the insoluble part, be compared with that of the silica, it is almost in the proportion of 1:3. We might suppose from this that the chief constituent of the msoluble part is a mineral f the formul © of the formula MEO} sios; and that the soluble part, which is so rich in magnesia, has for its chief constituent a mineral of a formula similar to olivine, 3MgO, Si0*. But it is most probable that the mineral constituents are themselves mixtures, as Rammelsberg assumes to be the case with many similar meteorites. The chief mass of the meteorites of Mezé-madaras would then be composed of a mixture of oli- vine, augite, and labradorite, containing besides, nickeliferous iron, iron pyrites, graphite, and a small quantity of chrome- iron ore. [ 144 J XVIII. On the Density of certain Substances (Quartz, Corundum, Metals, &c.) after fusion and rapid cooling. By M. Cu. Sarnte-CiarrE DEvILLE*. * the Comptes Rendus, vol. xx. p. 1453, I communicated the results of some experiments which establish a notable dif- ference between the density of certain crystallized minerals and that of the vitreous bodies obtained by subjecting those minerals to fusion and rapid cooling. I have thus shown that these differences, referred to the primitive density of the crystallized mineral, were,— For alabrador . . . . 0:06 For a felspar.... |... ... 0:08 Forahornblende . . . O12 Foran augite . . . . O14 For avesuvian . . . 0:16 From which it may be inferred reciprocally, that, in the act of crystallization, a very remarkable concentration of matter to a maximum of density takes place in these substances. All these minerals are silicates: it was therefore natural to inquire whether the same effect would show itself with crystal- lized silica or quartz. That this is the case I have been able to assure myself, through the obliging assistance of M. Gaudin, who has been kind enough to place at my disposal a simple and ingenious apparatus by means of which he obtains a very high temperature, I have been thus able to obtain with the greatest facility hyaline quartz melted into small drops, or in lumps. I have carefully determined in the first instance the density of the quartz itselft ; here are the numbers which I obtained :— 1. Fine crystal of quartz, perfectly colourless and 2-663 transparent. JF» fe Fel saiedqumieoe atioe 2. Quartz extracted from a granite of a medium \ 9, ar Aad leee geth a a ath eke oye . Quartz from porphyry, composed of quartz and 9-668 felspar ianly' 5-975: Sia oa a Seid soot . Quartz distributedin an irregularmannerin a rock of Guadaloupe, with labrador, and apparently -2°653 formed by concretion (mean of four experiments) Mean... ....» . .2°656 Se ow * Comptes Rendus, vol. xl. p. 769. + The densities cited in this note are taken for the most part with powder of a uniform grain obtained by means of two sieves, rejecting what passed through the finest and what remained upon the coarsest. All the numbers are referred to water at its maximum density. On the Density of Quartz, Corundum, Metals, &c. 145 Several fragments of No. 1, fused and cooled suddenly, pre- sented the following densities :— small rounded elabules: rs. oseteer ie. oy sos ough 2 2222 Fragments drawn out and elongated . . . . . 2-209 Same glass in very small fragments . . . . . 2:221 Same glass in powder, fine and homogeneous . . 27228 Mister OAs OF, NBZB20 The density of this quartz glass, referred to that of the primi- tive crystal 2-663, shows a diminution of 0°17. Of all the minerals which enter abundantly into igneous rocks, quartz seems to be that which possesses in the highest degree the remarkable property of assimilating to itself, during cooling, a certain quantity of heat, which maintains, even after solidifica- tion, the molecules at an abnormal distance apart. This property is of a nature to justify the hypothesis of a surfusion, which several geologists, and more particularly M. Fournet, have caused to enter into their appreciation of the circumstances which have accompanied the solidification of the rocks which, like granite, exhibit quartz m considerable proportions. Sulphur is known to be one of the bodies most easily subjected to the phenomena of surfusion. Experiments which I have already communicated to the Academy (Comptes Rendus, vol. xxv. p. 857) gave me, between the density of soft sulphur immediately after its preparation, and that of natural octahedral sulphur, a difference which amounts only to 0:07 of the latter. But this number is evidently a minimum ; for, as I indicated in the same note, the transformation of the soft or vitreous sulphur is ex- ecuted in the first moments with extreme rapidity. The metals and their compounds {excepting the silicates) seem, on the contrary, to have but little tendency to assume this peculiar abnormal condition. The passage to the crystalline state is almost immediate, however quick the cooling may be. Crystallized bismuth and the metal suddenly cooled, gave respectively the numbers 9°935 and 9°677. ‘Tin cooled very slowly, and the same metal cooled by being poured into water gave 7°378 and 7°239; which indicate for these two metals, in the two circumstances, a difference of density amounting only to about 0°02 of the maximum. With lead the phenomenon is still less pronounced; for between lead poured into water and small imperfect crystals of the metal, extracted from masses of the same lead cooled with great slow- ness, I found a difference of about one hundredth, but in the inverse sense (11°363 and 11254) *., * Another experiment was made with lead precipitated electro-chemically, and with the same lead melted and run; I obtained the numbers 11°542 and 146 Royal Society :— Sea-salt in very beautiful colourless crystals gave* . 2*195 The same, fused and rapidly cooled, was evidently in a 9-904, state of perfect crystallization, and gave . . . that is to say, exactly the same number. Thus, then, there are substances which, contrary to sulphur, quartz, and the silicates, have only a very feeble tendency, or none at all, to assume, even momentarily, the vitreous state. It might be demanded, to which of the two categories does alumina belong. Natural corundum in small colourless crystals gave me a density of 4-022; the same crystals, fused with the gas blowpipe of M. Gaudin, had a density of 3-992,—an insensible difference. There is not, therefore, a glass of corundum, as there is of quartz, and this physical property of alumina, as all its chemical properties, directly attaches aluminium to the group of metallic bodies. [We observe with pleasure the present tendency of experimenters to inquire into the influence of molecular arrangement upon density. The subject is one of great importance, and strongly solicits search- ing examination. Our handbooks of natural philosophy and che- mistry probably contain numerous erroneous statements as to the influence of mechanical pressure upon density; and he who places this question on safe experimental foundations will do a good service to science. We could have wished that the interesting paper before us were a little more precise in the description of the mode of cool- ing adopted, and of the appearance of the bodies after having been cooled.—Ebs. } XIX. Proceedings of Learned Societies. ROYAL SOCIETY. [Continued from p. 79.] May 24, 1855.—The Lord Wrottesley, President, in the Chair. fis following communication was read :— “On the Theory of the Electric Telegraph.” By Professor William Thomson, F.R.S. The following investigation was commenced in consequence of a letter received by the author from Prof. Stokes, dated Oct. 16, 1854. 11°225, which give a difference equal to 0°027 of the first density, and in the same sense as that of tin and bismuth. But such is the rapidity with which this finely-divided lead is transformed into carbonate in the air, that it was necessary to convert it into sulphate to deduce the weight of the matter employed. Does this complication cast some uncertainty on the first number, or ought we not rather admit it as the density of lead per- fectly crystallized ? * ‘In the essence of turpentine, the density of which had been previously determined. Lae: Prof. Thomson on the Electric Telegraph. 147 It is now communicated to the Royal Society, although only in an incomplete form, as it may serve to indicate some important practi- cal applications of the theory, especially in estimating the dimen- sions of telegraph wires and cables required for long distances ; and the author reserves a more complete development and illustration of the mathematical parts of the investigation for a paper on the conduc- tion of Electricity and Heat through solids, which he intends to lay before the Royal Society on another occasion. Extract from a letter to Prof. Stokes, dated Largs, Oct. 28, 1854. “Let c be the electro-statical capacity per unit of length of the wire; that is, let ¢ be such that cv is the quantity of electricity required to charge a length / of the wire up to potentialv. Ina note communicated as an addition to a paper in the last June Num- ber of the Philosophical Magazine, and I believe at present in the Editors’ hands for publication, I proved that the value of ¢ is ee if I denote the specific inductive capacity of the gutta 2 log R percha, and R, R’ the radii of its inner and outer cylindrical surfaces. “‘ Let & denote the galvanic resistance of the wire in absolute elec- tro-statical measure (see a paper ‘ On the application of the Principle of Mechanical Effect to the Measurement of Electromotive Forces and Galvanic Resistances,’ Phil. Mag. Dec. 1851). “Let y denote the strength at the time ¢, of the current (also in electro-statical measure) at a point P of the wire at adistance 2 from one end which may be called O. Let v denote the potential at the same point P, at the time ¢. “« The potential at the outside of the gutta percha may be taken as at each instant rigorously zero (the resistance of the water, if the wire be extended as in a submarine telegraph, being certainly inca- pable of preventing the inductive action from being completed in- stantaneously round each point of the wire. If the wire be closely coiled, the resistance of the water may possibly produce sensible effects). ‘Hence, at the time ¢, the quantity of electricity on a length dw of the wire at P will be vedz. “The quantity that leaves it in the time d¢ will be dy dt a dz, « Hence we must have FEY EPO na (1) a * ; “But the electromotive force, in electro-static units,at the point P, is _ dv dx’ and therefore at each instant OTL UE a a IP (2). 148 Royal Society :— «Eliminating y from (1) by means of this, we have aan cases Wesel (3), which is the equation of electrical excitation in a submarine telegraph- wire, perfectly insulated by its gutta percha covering. «« This equation agrees with the well-known equation of the linear motion of heat in a solid conductor; and various forms of solution which Fourier has given are perfectly adapted for answering practi- cal questions regarding the use of the telegraph-wire. Thus first, suppose the wire infinitely long and communicating with the earth at its infinitely distant end: let the end O be suddenly raised to the potential V (by being put in communication with the positive pole of a galvanic battery of which the negative pole is in commu- nication with the ground, the resistance of the battery being small, say not more than a few yards of the wire); let it be kept at that potential for a time T; and lastly, let it be put in communication with the ground (i.e. suddenly reduced to, and ever afterwards kept at, the zero of potential). An elementary expression for the solution of the equation in this case is al ggiment sin [2nt—zn*]— sin [(t—T)2n—zn*] pair 7), n where for brevity $i emg (ike Was Oe eae That this expresses truly the solution with the stated conditions is proved by observing,-—Ist, that the second member of the equa- tion, (4), is convergent for all positive values of z and vanishes when z is infinitely great; 2ndly, that it fulfils the differential equation (3); and 3rdly, that when z=0 it vanishes except for values of ¢ between O and T, and for these it is equal to V. It is curious to remark, that we may conclude, by considering the phy- sical circumstances of the problem, that the value of the definite integral in the second member of (4) is zero for all negative values of ¢, and positive values of z. «This solution may be put under the following form, OV c $ =a aof dne *” cos(2n0—zn*) « ws (6)? a) te) 0 which is in fact the primary solution as derived from the elementary j it 1 ae ne ain A es 3 type cos (27 —zv 7) cor eer given by Fourier in his investiga- tion of periodic variations of terrestrial temperature. ‘«« This, if T be infinitely small, becomes oA aie (a ae 3 v=—T] dne con( Date") sc ore eu eaee a 0 Tv which expresses the effect of putting the end O of the wire for Prof. Thomson on the Electric Telegraph. 149 an infinitely short time in communication with the battery and immediately after with the ground. It may be reduced at once to finite terms by the evaluation of the integral, which stands as fol- lows :— ie 9) : ty a when ¢ is positive, { dne*” cos( 2nt— an!) == me dt . 0 2 and when ¢ is negative, =0. And so we have Vz -% v=T ARR a at RO. de €:) 4 Ant? or by (6), when ¢ is not infinitely small, t a) ss 2 : (9), Qr ¢—-TO? or which is the same, 2 *¢t0Y, It is to be remarked that in (9) and (10) the limits of the integral must be taken 0 to ¢ (instead of t—T to ¢, or 0 to T), if it be de- sired to express the potential at any time ¢ between O and T, since the quantity multiplied by d@ in the second number of (6) vanishes for all negative values of 0. «« These last forms may be obtained synthetically from the follow- ing solution, also one of Fourier’s ‘elementary solutions :— Pad e # Q \/; v= Satie Moe oe see ae ae é me ¢ which expresses the potential in the wire consequent upon instan- taneously communicating a quantity Q of electricity to it at O, and leaving this end insulated. For if we suppose tle wire to be continued to an infinite distance on each side of O, and its infinitely distant ends to be in communication with the earth, the same equation will ex- press the consequence of instantly communicating 2Q to the wire at O. Now suppose at the same instant a quantity —2Q to be com- municated at the point O! at a distance (11), — on the negative side ke of O, the consequent potential at any time ¢, at a distance = c along the wire from O, will be . 2 _@+a)? Qfe #% e 4 } Cf FP |p I pa ee ee Se (12) ; - fu 1% 150 Royal Society :-— and if @ be infinitely small, this becomes Vee . (18), 2m t which with positive values of z, expresses obviously the effect of communicating the point O with the positive pole for an infinitely short time, and then instantly with the ground. « The strength of the current at any point of the wire, being equal to _ ; - ~ as shown aboye, in equation (2), will vary proportionally az dv dv fo =- ‘or to a The time of the maximum electrodynamic effect wv Zz of impulses such as those expressed by (11) or (18) will be found by determining ¢, in each case, to make a maximum. Thus we find a? hea* =— =—_— ae 6. 8 as the time at which the maximum electrodynamic effect of connect- ing the battery for an instant at O, and then leaving this point in- | sulated, is experienced at a distance 2. “In these cases there is no regular ‘velocity of transmission.’ But, on the other hand, if the potential at O be made to vary regu- larly according to the simple harmonic law (sin 2nz), the phases are : propagated regularly at the rate 24 / a as is shown by the well- known solution ae —znt U=—eE ain (Ong—an") ohh ea (14). The effects of pulses at one end, when the other is in connexion with the ground, and the length finite, will be most conveniently investigated by considering a wire of double length, with equal positive and negative agencies applied at its two extremities. The synthe- tical method founded on the use of the solution (11) appears per- fectly adapted for answering all the practical questions that can be proposed. “‘To take into account the effect of imperfect insulation (which appears to have been very sensible in Faraday’s experiments), we may assume the gutta-percha to be uniform, and the flow of electri- city across it to be proportional to the difference of potential at its outer and inner surfaces. The equation of electrical excitation will then become Q Tat ES SS * We may infer that the retardations of signals are proportional to the squares of the distances, and not’to the distances simply; and hence different observers, believing they have found a “velocity of electric propagation,’ may well have obtained widely discrepant results; and the apparent velocity would, ceteris pari- bus, be the less, the greater the length of wire used in the observation. Prof. Thomson on the Electric Telegraph. 151 and if we assume h 2250 5 I aa Geet 5 (16), we have ae ? a ME eas apa tn age oe Ce) an equation, to the treatment of which the preceding investigations are applicable.” Extract from Letter to Prof, Stokes, dated Largs, Oct. 30, 1854. **An application of the theory of the transmission of electricity along a submarine telegraph-wire, shows how the question recently raised as to the practicability of sending distinct signals along such a length as the 2000 or 3000 miles of wire that would be required for America, may be answered. The general investigation will show exactly how much the sharpness of the signals will be worn down*, and will show what maximum strength of currert through the ap- paratus, in America, would be produced by a specified battery action on the end in England, with wire of given dimensions, &c. “The following form of solution of the general equation which is the first given by Fourier, enables us to compare the times until a given strength of current shall be obtained, with different dimensions, &c. of wire ;— ht iv _ at v=e ke, SA;sin (x7) -e, keP™, If 7 denote the length of the wire, and V the potential at the end communicating with the battery, the final distribution of potential in the wire will be expressed by the equation e(l—#) Wh ¢—(l—2) Vk SV evi sent Na 4 which, when 4=0, becomes reduced to v=V(1-4), corresponding to the case of perfect insulation. The final maximum strength of current at the remote end is expressed by v 2h a 1” efVh—e—lvh ’ v or, when A=0, Yr Hence if we determine A; so that * See the diagram of curves given at p. 156. 152 Royal Society :— : aa e(l—2) Wh @—(I—2) Vh SA; sin (“T) = =e ie when z>0 and | cb Sb| Sb | 16 60.87 21.67 $3.97 Lg1.6z - £$z.62 "gz ES, |ecseeeeel 6x. *g *s | ems | ze | zr gf| SE | of $1.62 70.62 of.6z 9gt.6z 979.62 Sz gt. gi. of. *s | ms | ms | SE | gob cel €€ 6+ 98.87 16.92 92.62 £29.62 £99.62 “bz flats 21. Lo. | -ass | -s | «ms | $6£ | ¥E | S.9f| LE | of 20.6% 30.62 $2.62 f9v.62 g LS .6z ‘£zO seeeesresleereeees] or, | ggg lemum| smu | PE | dE Sz| 60 | 6z $9°6z LL.6z 09.62 ZSL.6z $69°6z ZZ Pedtecane| ieeatessel ene 5 “a "9 gf LE | S.1z| x1 gz LL.6z 99.6z £9.62 ZoLl.6z £08.62 “1z ey |r 9 ge | gf tz| Lr | zE 1.62 £2.62 93.62 g16.6z £60,0£ ‘oz Goze |r eeesselonteoerni) ay | sage eg gi | gf Sz|-oz | 2 $3.62 96.62 $0.08 ogr.o£ 97,08 “61 seesetsee eeteeneesletseeses! ages | og | ga | 6£ | £6E S&| xz | of 91.08 gr.o£ 13.62 $Lo.0f bIZ,0£ *gI sesseesesleereeeres! og | omar | egu | ELE | LE | S.gz! SE fb 61,0£ Z1.0£ 0g.6z S£o.0£ 980,08 Lt seeiess -mum| “m | tm | gob | zh SE! 62 Le £6.6z $3.62 76.62 £gr.of£ 197,08 ‘or ¢ or “m | cm | om | Seb] Lb bb) Sz | gb oL.6z 79.67 LL.6z gto.,of Z7Z,OF “Sr fo. om | om | om Ly | Lb | S.9£| ob | 6b 2L.6% ¥S.62 79.62 006,62 S10,0£ “br apn enseas ‘m | a | emu | rb | +E | 6.2] Sx gf 0g.6z £6.62 9L.6z $10.0£ L60,0£ “£3 ‘mu mum| as | z&| rf | €2| €1 | £6 | 06,62 bL.6z bb.6z 269.62 $gg.6z | sax eaeas.s| «mu | em | emg’ | eIS_[. ZS of| €z | €€ $3.62 00,08 oL.6z 006.6z €£0,08 ‘II teeeerees! 77. seteeeeesl emu] MUM) UO gt Iv of| zz SE 20.0£ Lo,of 7.62 Lfo.0£ 6Lo,0£ “OL ssttecsee|seseeeessleseeeeeee! emg [emu] cam | gf | SE Grilieas 2 laS6 Lr.0£ £r.0£ $1.62 96.62 oor ,of 6@ vo. | gr. |rrererrrs| ou |emuu| ‘ou | SE] of | of] 61 | SE Lo,0f 38.62 9£.6z 795.62 13.62 8 oS. Sane | ema | eau-| ow gf | of vE| Le | cb LL.6z 09.6z gr.6z ogt.6z 0g$.6z “L gh. [terreeeslereeeeee! om | emu | mm | LE | PE zi| gz | cb $5.62 Sv.6z 66.32 £L£.6z $0S.6z Te) Fee boactnocd Perec earn onal iat TS || aks LE\ of | bb £2.62 ££.6z 07.62 60S .6z LSS .6z aS ce ro. |:ma| «a | ems | 68 | Sob 6£| of | Lr 6£.6z 2.62 0S .6z 069.62 878.67 + 6z. zo. |*MUM|‘muu| ‘am | $gb | Lb 1£| 1£ | ov $9.6z $9.62 39.62 £36.62 836.62 “t Go; to looms lena! ou zy| rb | of| oz | tb 19.62 $3.62 £5.62 11g.6z 648.62 °t So. fo. |ueo| ‘ma | -mu | $S£ | 566 | gf] ££ | ob | $6.62 06,62 oL.6z 493.62 zlo.of | 1 p fo ° g res ee tl een | "een co ' 6 4H u's ow “ar ‘xe 20d Ee g Fi ae Z ae wad Fg )*u0-e $6 a uy | xeyr | = ‘urd $8 +6 ra WW W ‘ees 2.0 $ i 2.0 8 | Sell eo | 2 | & [BS | F |FE | pms | EF | omen | mompms Somuo oP “oUMsTMO waite e = yo skeq “uteyy “pula, *JaqaWIOULAeY J, | SPALL fi | , “RANNUO ‘asun yy younpung jp “MOSNOT) *C *AAY 247 Ag pun {NOLSOG 7D “TBA “AT fq UOpUory Wau “MOIMSIHO JD hyaraog pounynaysoyy ay) fo uapsny oy} 1D uosdmoyy, “AI Aq app suorpasasggQ va.bojosoajapy THE LONDON, EDINBURGH anv DUBLIN PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. [FOURTH SERIES.] MARCH 1856. XXI. Remarks on the Estimation of Sulphur in Iron, and on the Solubility of Sulphate of Baryta in Nitric Acid. By EK, Cuam- BERS NicHotson and Davin 8. Price, Ph.D.* i gee method usually employed for estimating the amount of sulphur in a metallic substance, is to act upon it either with nitric acid or aqua regia, and then to precipitate the sul- phuric acid with.a solution of a salt of baryta. By pursuing this plan for the determination of sulphur in cast iron, the solu- tion obtained by oxidizing 10 grammes of the metal with nitric acid was evaporated to dryness for the purpose of rendering the silicic acid insoluble, the residue then digested with dilute hydro- chloric acid until free from iron, and the sulphuric acid in the solution thus obtained precipitated with chloride of barium. The quantity of sulphur found by this method will be seen by the Table, column 1, far to exceed that afterwards arrived at by adopting another process. This process consisted in dissolving the same weight of iron in hydrochloric acid, and passing the gases evolved through a solution of acetate of lead slightly aci- dified with acetic acid. The precipitate of sulphide of lead thus produced was collected.on a filter, washed, dried, and the per- centage of sulphur calculated from the weight obtained (see column 2). The residue from the iron, consisting of graphite and silicic acid, was collected on a filter, dried, and then fused with a mixture of nitre and carbonate of soda, in order to ascer- tain if all the sulphur had been eliminated as hydrosulphuric acid. ‘The fused mass was dissolved in water, the solution aci- dified with hydrochloric acid, and then evaporated to dryness to separate silicic acid. ‘To the solution obtained by digesting this * Communicated by the Authors. Phil, Mag. 8, 4, Vol. 11. No. 71, Mar, 1856. N 170 Messrs. Nicholson and Price on the residue with water, and after filtration to separate the silica, the addition of chloride of barium produced in no instance more thari*the faintest indications of the presence of sulphuric acid. The per-centages indicated in column 2 may be regarded as correct, as we have verified them by the employment of perfectly pure nitric acid, and by adopting the precautions to which we shall immediately allude. Per-centage of sulphur. Gray pig-iron from different works. Column 1. Column 2. By BaO S03. By Pbs. 1 0°32 0:10 2 0:28 0:044 3 0-52 0-055 4 0-72 0:081 5 0-45 0-036 The cause of the error by the former process we found to be owing to the presence of sulphuric acid in the acids employed, which we failed to detect by the ordinary method of testing for this impurity, namely by dilution of the acids with a large volume of water before adding a solution of a baryta salt. By evaporating the acids nearly to dryness in a platinum dish and then adding water, the sulphuric acid or sulphate with which they were contaminated was recognized. The fact of the solu- bility of sulphate of baryta in mineral acids was not known at the time when we made the above examinations, which was in the autumn of 1858*. It is not our intention now to dwell upon the subject of the amount of sulphur in different varieties of pig-iron, and the manner in which the property of the iron is affected by it. This we reserve for a future communication. From what has already been stated, it will be seen that errors of two kinds may arise when nitric acid is employed: one where evaporation to dryness is necessary, when, if the acid contain sulphuric acid, an excess of sulphur will be obtained; the other where precipitation is proceeded with in very acid solutions, in which case a loss will result from the solubility of sulphate of baryta in the acid. To prevent this latter source of error, it is necessary either to expel the excess of acid by evaporation, or to neutralize it with an alkali previously to precipitating with a baryta solution. With these precautions sulphur can be cor- rectly estimated by oxidation with nitric acid. The following Table contains the results of some experiments * By an abstract of a paper in No. 16 of the Proceedings of the Royal Society, Professor Calvert has, we see, been engaged in experiments on the solubility of the sulphate of baryta. Estimation of Sulphur in Iron. 171 which were instituted in order to gain an idea of the extent to which the precipitation of BaO SO? is influenced by nitric acid. Le EL nT ERS ace a RSE, aa eC NOI Sr ee Cubic centi- Sulphate of potash Order of ex-|Metresof nitric] Cubic cen- ; , j area ae ap at | meres of tuTale 119 Otwersations ploye AL of baryta. Copious precipitate of nitrate of 1 14 14 baryta which appeared after the lapse of a short time. 2 28 Precipitate of BaO NO® less than in Exp. 1. 3 * 56 No precipitate after 16 hours. a Ras 84 do. 5 eh 112 do. 6 aad 168 do. Sulphate of potash equivalent to ‘027 grm. of sulphate of baryta. 7 14 Precipitate of BaO NO5 same as Exp. 1. 8 28 do. do. but small. 9 ne 56 No precipitate after 16 hours. 10 84 me do. ll 168 Ree do. Sulphate of potash equivalent to '040 grm. of BaO SO3, Precipitate of BaO NO® same as 12 14 Exp. 1. 13 28 ‘A cloud of sulphate of baryta after 10 hours. 14 56 rK: Faint precipitate do. 15 168 do. 0. No precipitate do. after 16 16 560 hours. ° Nitrate of baryta precipitated 7 28 28 es { after some minutes. 18 eae 56 hs No precipitate after 16 hours. 19 ay 112 A do. Sulphate of potash equivalent to +120 grm. of BaO 503, No precipitate at first. After 20 14 28 some minutes an appreciable one of BaO S03, 21 14 do. do. anda precipitate of nitrate of baryta, In the above experiments the sulphate of potash was dissolved in water and the nitric acid added to it. The same volume of a solution of BaCl, containing about twenty times the quantity of N2 172 Mr. E. W. Davy on the comparative Value of Peat baryta necessary to precipitate the sulphuric acid present, was added to each. After recording the above observations, a further addition of BaCl was made to each of the solutions in the first fifteen experi- ments, and the results noted down after a lapse of fourteen hours. In Exps. 1 and 2 the quantity of BaO NO® was increased. In Exp. 3 a precipitate of BaO NO® was produced. On the appli- cation of heat to these solutions the precipitates dissolved, show- ing that no BaO SO® had been deposited. In Exps. 4, 5, and 6, there was a turbidity occasioned by BaO SO%. In Exps. 7, 8, 9, 10, 11, 12, 13, 14, and 15, there was a pre- cipitate of BaO SO°. The addition of a large quantity of BaCl to Exp. 19 caused a copious precipitate of BaO SO®. From these experiments, it will be seen that the amount of BaO SO® precipitated is influenced by the quantity of BaCl present in the solution. We have not ascertained whether the presence of other salts would have produced the same effect. In the experiments where nitrate of baryta alone is preci- pitated, a confirmation of Berthollet’s law of chemical affinity is afforded. Sulphate of baryta we find to be also soluble in dilute hydro- chloric acid and aqua regia, but not to the same extent as in nitric acid. In the estimation of sulphur in substances where it exists in small quantity, such as in vegetable and animal sub- stances and in metals, and where, owing to the necessity of ope- rating upon a large amount of material, and consequently of taking a proportionate quantity of nitric acid, we have no doubt that errors similar to those which we experienced have frequently occurred. XXII. On some Experiments made with a view to determine the comparative Value of Peat and Peat-charcoal for Agricultural purposes. By Epmunp W. Davy, A.B., M.B., M.R.LA., Lecturer on Chemistry in the Carmichael School of Medicine, &c., Dublin*. ye no former period has the importance of animal excremen- titious matter to agriculture been so clearly understood as at present; while the growing attention which is now paid to the sanitary condition of towns, and the methods which have been discovered of deodorizing such matter, afford increased faci- lities of converting it into the most valuable manure. Many substances, as chlorine, the chloride of lime and of zine, * Communicated by the Author. and Peat-charcoal for Agricultural purposes. 173 &c., possess considerable deodorizing properties, and may in cer- tain cases be usefully employed for sanitary purposes, but are quite unfit to be used in making manures from animal excreta, because they either decompose some of the most valuable con- stituents of those matters, or are injurious to vegetation. The most important substances which have yet been proposed, both for deodorizing and the manufacture of manures from pu- trescent matters, are peat and peat-charcoal. The deodorizing property of vegetable charcoal, from whatever source, has long been known; that of uncharred peat was first clearly ascertained by my father, Professor Davy, who at the scientific meetings and lectures of the Royal Dublin Society, and subsequently in a pamphlet, called public attention to it; and his statements have since received the most ample confirmation from various sources. Peat, therefore, in its charred or un- charred state, may be used as a deodorizer for sanitary purposes, and it becomes little more than a question of expense which should be employed for this object. A difference of opinion, however, is entertained whether peat or peat-charcoal is the best adapted to deodorize animal excreta, &c., where the object is to manufacture manures. The advocates for the use of peat-charcoal allege, as one of the most important of its properties, that, when mixed with decomposing animal excreta, it absorbs and retains the ammonia which is evolved from such matter. If peat-charcoal really does this, it effects a valuable object, as the importance of ammonia as a food of plants and a fertilizer of the soil is well established. With a view to throw some light on this subject, if possible, I made some comparative experiments with peat and peat-charcoal on stale urine, which by decomposition had become highly am- moniacal. This urine was put into a well-stoppered bottle and kept for the experiments. As peat from different localities differ in certain respects, 1 employed the same sods, charring one part of each, and leaving the other part uncharred. The peat on being converted into charcoal in a close crucible, was, on cooling, immediately put into a dry bottle and kept well corked. The uncharred peat was broken into pieces and placed in a similar bottle, and both on being used were reduced to the state of coarse powder, the particles of each bemg about the same size. Having taken equal weights of the powdered peat and peat- charcoal, I put them into two similar evaporating dishes, and intimately mixing each with the same quantity of the ammo- niacal urme, left the mixtures exposed to the air for some days under an open shed where they were protected from the rain. The proportions I employed were 500 grains of peat or peat- charcoal to 6 drachms by measure (or about 355 grains by 174 Mr. BE. W. Davy on the comparative Value of Peat weight) of urine. I may observe, on mixing the urine with the charcoal a very strong odour of ammonia was immediately dis- engaged, and the continued evolution of ammonia from the mix- ture for several days was readily detected by moistened turmeric paper ; whereas in the case of the peat, no odour of ammonia was perceptible on making the mixture, nor could the disengagement of the slightest portion of it from the mixture be detected by means of turmeric paper when examined from day to day. Having previously determined by experiment how much am- monia was contained in a given quantity of the ammoniacal urine ; after the mixtures had been exposed to the air for four days, I divided each into two equal parts, and ascertained how much ammonia was present in one part of each, containing three fluid drachms of the urine. The following are the quantities of ammonia furnished by the same amount of the urine alone, and when mixed with peat and peat-charcoal, and treated in the manner described. Amount of Ammonia in 8 drachms by measure. In the urine alone . . . . 0947 part of a grain. do. with peat-charcoal 0°233 waa Loss therefore . 0°714 eos do. with peat . . . 1:105 oes These results show, that when the urine was mixed with peat- charcoal and exposed to the air for only four days, it lost 0°714 part of a grain of ammonia, which is more than three-fourths of the entire quantity contained in the urine; whereas in the case of the peat, instead of there being any loss of ammonia, there was a slight excess over that existing in the urine alone, which is easily explained by the fact that peat itself always contains a minute quantity of ammonia. In these experiments, the quantities of ammonia were ascer- tained by boiling the urme and the mixtures for some time in a retort with a strong solution of caustic potash, and collecting the evolved ammonia in a given quantity of diluted sulphuric acid of known strength, and determining its amount by Peli- got’s method, which is one much used by chemists on account of its accuracy and expedition. I made also the following experiments, which confirm the results of those just noticed. Having weighed 300 grains of peat and of peat-charcoal, I carefully mixed each with half an ounce by measure of the same urme as that employed in the former experiments, and putting each mixture on a small saucer placed it in a large plate holding some mercury, and having arranged a small tripod supporting an evaporating dish contain- and Peat-charcoal for Agricultural purposes. 175 ing some diluted sulphuric acid of known strength over each mixture, finally covered the whole with a bell-glass ; the mercury serving to exclude the air. Having left the mixtures thus covered for five days, I removed the bell-glasses and examined, by Peli- got’s method, the acid contained in each evaporating dish. I could not detect any ammonia in that placed over the peat, show- ing that none had been evolved, and that the peat had completely retained and fixed, as it were, the volatile carbonate of ammonia existing in the urine. On the other hand, in the case of the peat-charcoal, the acid indicated the absorption of 0:288 part of a grain of ammonia, or considerably more than one-fifth of the entire quantity existing in the urine of the mixture which had been evolved. I repeated this last experiment, mixing 500 grains of peat and of peat-charcoal with 1 fluid ounce of the same ammoniacal urine, and employing a similar arrangement as in the last, with the exception of using diluted muriatic instead of sulphuric acid for absorbing the evolved ammonia. After the mixtures had been left for sixteen days, [ removed the bell-glasses, and found that the mixture with peat-charcoal had a slight urinous smell, and was still evolving ammonia, which was apparent both by its odour and its action on turmeric paper suspended over the mixture ; whereas the mixture with peat had no smell what- ever, and no evolution of ammonia could be detected by means of turmeric paper. On evaporating to dryness in a water-bath the two acids placed over each mixture, I obtained in the case of the peat-charcoal a residue of 5°7 grains of muriate of ammonia, which is equivalent to 1°812 grain of ammonia, or just about three-fourths of the entire ammonia contained in the urine em- ployed which had been evolved and afterwards absorbed by the acid. On the other hand, in the case of the peat there was an inappreciable residue, which on being dissolved in a little water and treated with caustic lime, gave a slight indication of ammonia, showing that only a very minute quantity had been evolved; and this may in part be accounted for by the peat being mixed with a larger proportion of urine in this than in either of the two former experiments. The loss of ammonia in the case of the peat-charcoal in these two latter comparative experiments is not so great in proportion, considering the time occupied, as in that of the former ; but this is easily explained by the surface exposed not being so large, and the experiments being made under bell-glasses, the same facilities for the evolution of ammonia were not present as when the mixture was exposed to the open air; but had the experi- ments been carried on longer, a much greater loss of ammonia would have taken place; for on opening the bell-glasses in each, 176 Mr. E. W. Davy on the comparative Value of Peat it was found that the mixture with peat-charcoal was still evol- ving ammonia. These experiments show that peat-charcoal (contrary to the many statements which have been made by its advocates) has very little power of absorbing and retaining the ammonia of ex- crementitious matter when mixed with it ; whereas peat possesses this valuable property in an eminent degree, and absorbs and retains it in a most striking manner, which would appear to be owing (at least in part) to peat containing some substance which acts the part of an acid in neutralizing and fixing the ammonia of the volatile carbonate; for I found that when peat in certain proportions was mixed with urine which was highly alkaline (from the quantity of carbonate of ammonia it contained), and the mixture filtered after a short time, that the filtrate, though it contained ammonia, was quite neutral to test-papers, showing evidently that the ammonia of the carbonate had combined with some other acid to form a neutral salt. The evolution of am- monia in the case of peat-charcoal seems to arise from two causes, namely, its inability to retain the volatile carbonate of ammonia existing in decomposing animal matter, and the property I have observed it to possess of decomposing to a certain extent the fixed salts of ammonia, as, for example, the sulphate, phosphate, muriate, and urate which may be present in such matter, and converting them also into the volatile carbonate which is readily evolved. This latter property would seem to depend on the alkaline and earthy carbonates formed during the process of charring ; for when the charcoal was boiled for some time in diluted muriatic acid, and well washed with distilled water so as to remove as much as possible those salts, and again dried at a red heat, the power it possessed of decomposing the fixed salts of ammonia, though not completely removed, was, however, greatly diminished, which clearly shows its connexion with those substances. Peat, on the other hand, does not possess this pro- perty in the slightest degree. These facts prove the great su- periority of peat over peat-charcoal for agricultural purposes as regards the important substance ammonia; for by the use of peat, the ammonia is retammed more or less completely im the manure to exercise its fertilizing action on vegetation, whereas the peat-charcoal suffers it to be in greater part dissipated and lost. The foregoing results and statements, as regards peat-charcoal, are contrary to what might have been anticipated from the ex- periments of De Saussure and other chemists, who have shown that charcoal possesses the power of absorbing different gaseous substances, and particularly ammoniacal gas, in large propor- tion; but the circumstances under which they conducted their and Peat-charcoal for Agricultural purposes. 177 experiments were very different from those in the experiments described in this communication. ’ De Saussure, who appears to have made the most extended researches on this subject, when he ascertained that charcoal absorbed about ninety times its volume of ammoniacal gas, em- ployed perfectly dry and very dense charcoal made from boxwood (the denser the charcoal the greater its absorbent power), and in order that it might be as free as possible from air, heated the charcoal red-hot, and while in this state plunged it under ‘mer- eury and thus cooled it out of the contact of the air, and after- wards let it up into the gas. Such perfectly dry charcoal, and so free from air, could never occur in practice, and are not the conditions in which charcoal is placed when used as a deodorizer of animal excreta, &c.; for in addition to its having absorbed much air and moisture from the atmosphere in spite of the most careful mode of keeping, it becomes more or less completely wet on mixing it with excrementitious matters ; and the experiments of De Saussure show that the absorbing power of charcoal for different gases is greatly impaired by the presence of moisture. It appeared, however, interesting to me to ascertain what was the relative absorbent power of peat-charcoal, thoroughly dried peat, and of that in its ordinary state of dryness for ammoniacal gas. For this purpose I selected a good and tolerably dense sod of peat or turf, and having converted a part of it into charcoal, I made three small cubes of the same size as nearly as possible, one out of the charcoal, and two out of the uncharred part, one of which I then thoroughly dried by exposing it for many hours to a temperature of 212°F. The cube of charcoal, that it might be as nearly as possible under the same conditions in respect to dryness and absorption of air as the cube of dried peat, I left exposed to the air for some time and afterwards dried it at 212° F. The third cube was left in its ordinary state of dryness, which was found by drying another portion of the sod to contain about 20 per cent. of water. These cubes were then let up into gra- duated receivers filled with ammoniacal gas standing over mer- cury, and the following are the results of their absorption, the volume of charcoal or peat being taken as unity. Absorption of Ammoniacal Gas. Volumes. Re MONEO Af 8 Ree oe ay ig kee Peatyaried. at 21a Es BOS Peat in its ordinary state of dryness 50-0 containing about 20 percent. of water As the weight of the cube of peat-charcoal to that of the cube of dried peat in this experiment was in the ratio of 13 to 16-6, 178 Prof. Magnus’s Hydraulic Researches. the volume of ammoniacal gas absorbed by equal weights of the peat-charcoal and dried peat ought, by calculation, to be in the ratio of about 23:4 to 33:2. These results show that the absorbent power of peat-charcoal for ammoniacal gas, even in the dry state, is very much overrated, and is much less than that of dried peat, whether estimated by bulk or weight, and is far less than that of peat in its ordinary state of dryness. As regards carbonic acid, the great food of plants, peat has a decided advantage over peat-charcoal, as the former readily un- dergoes decomposition in the soil, particularly if it is in contact with decomposing matter (as excrementitious substances), and gives rise to carbonic acid in the soil, both to supply the wants of the young plant before its leaves are sufficiently formed to obtain this indispensable substance from the surrounding atmo- sphere, and to render soluble in water certain earthy salts, &c. required by vegetation, and present them in a state in which they can easily be taken up by the roots of plants. Charcoal, on the other hand, from its being so little lable to undergo change, or be oxidized and converted into carbonic acid at the ordinary temperature, would, under the same circumstances, fur- nish only a very minute quantity of carbonic acid, even after the lapse of a long period. Peat, likewise, from its greater elasticity, is better calculated than peat-charcoal to improve the texture, and render more per- vious to the air heavy clay soils deficient in vegetable matter ; and besides many other arguments which might be adduced in its favour, peat in the partially dried* and coarsely-powdered state in which it should be employed, would only be about one- fifth, if so much, of the expense of peat-charcoal. All these cir- cumstances show that peat is greatly superior to peat-charcoal in manufacturing manures for agricultural purposes. XXIII. Aydraulic Researches. By G. Maenvs. [Concluded from p. 107.] Jets from a cruciform aperture. 61. | hee an aperture be made in the form of a cross, as repre- sented in Plate II. fig. 17, in which the length of each slit, yy, is 40 millims., and the breadth 3 millims., then when the efflux is regular, i. e. when neither a rotation of the liquid nor any hindrance to the motion is present, the form will be obtained * The peat used in all these experiments, except those on the absorption of ammoniaeal gas, contained about 28 per cent. of water. Prof. Magnus’s Hydraulic Researches. 179 which is depicted in fig. 17 a, as seen by an observer who stands in the prolongation of zy. From the aperture zy,y,7' the water falls down in four arms which cross themselves, ye, ye, Y,¢,, &c., of which each has a strong edge. By the encounter of these four edges, every two form a surface, rpg. Since, however, the encounter is central, each surface bisects the angle formed by the edges by which they were made. The four surfaces formed in this manner have, hence, the position, fig. 17, marked by the dotted lines pp. They are at right angles to each other, and bisect the angles of the cross yy,y,y'. The edges ye stretch between them down to g. In the horizontal line going through this point, that is at p, the surfaces epg have their greatest breadth. Below this part they again assume thick edges, by whose encounter new surfaces, 2v, are produced. Since the edges pq and pg, &c. also encounter centrally, the new surfaces zv, &c. bisect again the angle which the edges pg, &c. form with each other, and are hence again at right angles to each other, and have the same situation as the arms 7é, Ye), Y,,€, Of the cross. I have seldom succeeded in obtaining more than twa such systems of surfaces under each other ; perhaps because the efflux orifice was not sufficiently accurately made; for the smallest difference in the dimensions of the individual arms zy or zy, deranges the symmetry of the surfaces rpg and their edges. The formation of a third and fourth system of surfaces is likewise rendered more difficult, from reasons similar to those to be afterwards mentioned in § 83. 62. If any of the before-mentioned disturbances occur in the efflux, the edges no longer encounter centrally, and the jet assumes a spiral form. There are, however, few cases in which such a spiral form is regular, for it is seldom that the disturb- ances act symmetrically on all four arms of the cross yy,y,y'. Fig. 17 ¢ represents this form as it was obtained by placing pieces of metal plate E exactly of the same size, and in the same position on the four arms ye, y/¢,, Ye, y'é of the cruciform aper- ture, fig. 17 6. If these pieces were not all exactly alike, or if they were not all placed symmetrically, the jet had not a regular spiral shape. The metal pieces E must not be too thick, for then the individual windings yp, y,p, y'p', &c. would separate. 63. How remarkable the form of the jet issuing from the cruciform aperture may be, and yet how similar to the pheno- mena hitherto observed, is seen when the efflux from one of the four arms of the cross is stopped, so that the efflux orifice has the form y, y,, ¥, fig. 18. The jet assumes, then, the form represented in fig. 18 a and fig. 186. Fig. 18 a represents it as seen by an observer standing at right angles to yxy, and fig. 18 4 as seen by one who stands in the prolongation of y#y,. 180 Prof. Magnus’s Hydraulic Researches. The water which falls from the three arms zy, xy, xy, forms, as in a former case, § 61, thick edges, ye, y,,e,,. which encounter centrally. Thereby result the two surfaces rpg and 7, p,q,, which bisect the angle made bythe edgesyeand y,e,,, as well as that by the edges ye, and y,e,, and which have the position ap and xp, fig. 18. But bythe central encounter of the edges ye and y¢,a third surface, wzv, is formed, which bisects the angle of these edges, or is at right angles to yxy, and consequently falls in the prolongation of the planezy,e,. It extends itself only towardsthe sidewz, and isscarcely perceptible on the other side, where it is met by the edge y,¢,,. The edges of the surfaces rpg and r,p,q, form by their encounter a new surface mn, which falls in the same plane with wzv. There , are formed, however, by the encounter of the surfaces rpq, 7,p,q, with the surface wzv, two new surfaces, hik and hji,k, A secon system of surfaces is not perceptible in this jet, because by the encounter of surfaces of unequal mass the motion is too irregular, and hence the connexion between the particles of water 1s too much disturbed. Jets from a square orifice. x 64. When the water issues from a square orifice, and when no hindrance, rotation, or other disturbing motion is present in the vessel, a jet is obtained whose form is similar to that shown in fig. 19, when viewed from a position perpendicularly opposite one of the sides of the square. Below the place of greatest contraction, 000, four surfaces, opq, &e., are seen whose productions pass perpendicularly through the centres of the sides of the aperture. Below this system of surfaces is a second and similar one, which also contains four surfaces, ww, &e. These latter bisect the angles of the first system, and consequently coincide in direction with the diagonals of the square aperture. To understand this better, a, 8,y, 5 repre- sent the horizontal sections of the jet at those places where. the dotted lines‘ aa, BB, yy, 55, cut the jet. Below the second there is a third system of surfaces, which again is similarly situated to the first ; and below that a fourth, whose surfaces are parallel with the second, and so on. I have often observed nine such sharply-defined surfaces below each other, and below these a considerable number which were not so sharply defined. After what has been said before, § 61, about the origin of such surfaces from a cruciform aperture, no further explanation is needed to show how the second system of surfaces is produced from the first, and from the second the following ones. But it is not so easy to explain how the first system of surfaces is formed, or how the peculiar form is produced, which the jet shows previous to the commencement of the first system. I will endeavour to explain the origin of this form, Prof. Magnus’s Hydraulic Researches. 181 Explanation. 65. The parts of the liquid arrive at the orifice in very differ- ent ways. The motion of each particle, and we will first consider that of a particle at the edge of the aperture, can be divided into a vertical and a horizontal component, and this latter can be again divided into two directions, of which the one is normal to the perimeter of the aperture, and the other at right angles to the normal. It is of course impossible to determine the magnitude of the motion of such a particle in different directions during the efflux, as also the relation of these motions for the whole of the particles which simultaneously pass over the edge of the aperture, since they may have attained the edge in very different ways. But before the liquid begins to issue, the whole of the particles at the bottom are under the same pressure. All those at the edge of the aperture move, when the latter has been opened, with equal velocity over the edge, since it is assumed that up to then no motion has occurred in the vessel. Hence they all begin their paths in the direction of the normal with equal velocity. But having passed over the edge of the aperture, there is in addition to the horizontal, a vertical motion. The resultants of these two change their direction continually, partly in consequence of the gravity of the particle, and partly in consequence of the pres- sure which the mass of liquid above exercises. But a change in the direction of the motion is principally effected by the cohesion which takes place between the parts of the liquid, and by the resistance which the mass of water in the interior of the jet opposes. These last actions of cohesion and of resistance induce principally the peculiar forms of the jets, for they are not the same for all particles passing from the edge of the aperture. 66. Let us consider first the resistance of the liquid in the interior of the jet to the horizontal part of the motion of a par- ticle passing from the edge of the orifice to the cross section of the jet immediately under it. It is manifest that if the orifice were a circle, this resistance would be equal for all particles which came from the circumference of the aperture. But if the aperture be not a circle, and those radii of curvature of its peri- meter which fall in the aperture be called positive, and those without negative, then the resistance to a force acting from without must be less at those points whose radii of curvature are positive, than at those points at which they are negative ; and it will be the less the smaller the positive radius of curva- ture. For at that part of the perimeter at which the radius of curvature is positive and smaller than at the adjacent parts, which therefore project more, the particles of the liquid are more 182 Prof. Magnus’s Hydraulic Researches. easily pressed to the side, because there are fewer particles near them whose inertia they have to overcome. Hence they oppose less resistance to a force acting at right angles from without than the less projecting parts. For the same reason, at those parts where the radius of cur- vature is negative, the resistance to a force acting at right angles from without is greatest when the radius of curvature is least. In a square aperture, the particles falling from the corners of the squares experience a less resistance in a horizontal direction than those descending from the sides. The particles of water coming from the projecting places experience a less resistance in passing from the edge of the aperture to the cross section underneath, and from this to a second, and so on, than the others. On account of this smaller resistance, the motion of the particles coming from the projecting parts of the orifice is more horizontal; and these particles reach the deeper cross section of the jet with less inclination than those from the less projecting.parts, and con- sequently produce a greater pressure against the liquid in the deeper cross section. 67. In the same manner, the cohesion or attracting force which takes place between the particles of the liquid acts so, that if the aperture be not circular, the directions of the particles coming from the edge of this orifice are not all changed alike ; for in consequence of this mutual attraction, the particles in any cross section of the jet would only be in equilibrio if the cross section were circular. Hence, in the cross sections which are not circular, there results a motion by which the perimeter is speedily changed into the circumference of a circle, But this motion is not the same for all particles in the same perimeter, Those which are at the prominent points, or where the radius of curvature is positive and least, are attracted with greater force to the interior of the jet, than those at the pomts where the radius of curvature is negative. Hence the particles coming from the projecting places also experience, in consequence of the cohesion of the liquid, a less hindrance to their horizontal motion than those coming from other points, and assume, in consequence of this mutual attrac- tion, a more horizontal direction than the latter. 68. Having a more horizontal direction, the pressure also which the particles falling from the prominent places of the aperture exercise on the interior of the jet, is greater than that which the rest produce. This greater pressure can even produce a cavity in the jet. This can be best obseryed by using an aper- ture of the form fig. 20, wherewith the water coming from the part bd produces a considerable cavity in the jet. Fig. 204 represents a vertical section. The particles of water coming Prof. Magnus’s Hydraulic Researches. 183 from d move inalmost a horizontal direction, dy, towards the jet issuing from the circular part of the aperture, and i consequence of the pressure which they exert, the concave surface gk is formed. 69. Similar phenomena to those with the aperture just men- tioned are seen with all angular orifices, and especially with a square one. The masses of water coming from the corners press stronger against the interior of the jet than those coming from the sides, and hence the former have the same relation to the latter as single jets which move towards each other. By the encounter of these jets is produced the first system of surfaces, and from that all following ones in the same manner as with the cruciform aperture, § 61, fig. 17. 70. That the peculiar action which the parts of water coming from the prominent places of the orifice exert is chiefly depend- ent on the less resistance which the horizontal part of their motion experiences from the mass of water contained in the jet, is evident from the fact, that when the efflux is so arranged that the parts of the liquid can only move in a vertical direction, this action is no longer exerted. By using an aperture in a thick wall instead of a thin one, the particles have, on leaving the orifice, only a vertical motion. Hence the form of the jet can only be changed by cohesion, and not by an inequality of resist- ance. But the changes produced by cohesion alone are far less than those produced by resistance and cohesion together. 71. If the water be allowed to issue from a tube 25 millims. long, and which has a square section as large as the aperture in the thin wall, and if care be taken that the tube is completely wetted and full, the jet assumes a circular section just on leaving the tube, and has neither the ventral segments nor any of the phenomena which are presented by the jet issuing from a thin orifice. The case is similar when, instead of the aperture, fig. 20, a tube is used whose section is equal to this aperture. The jet assumes then a section which is almost circular. Immediately below the aperture it appears broader, which arises from the fact that the particles issuing at d, fig. 20, although only acted upon by cohesion, are yet pressed by it towards the interior of the jet with a wuch greater force than are the other particles. The jet once broader, contracts again, is again broader, and thus these ventral segments are repeated several times. 72. By this, the difference of the efflux from a thin or thick wall is rendered clear. In using the latter, or a tube, and when all the parts move vertically, cohesion alone acts, and produces the changes of form. If, on the other hand, the aperture be made in a thin wall, the particles of the liquid move not only in the vessel in a more or less horizontal direction, but maintain 184 Prof. Magnus’s Hydraulic Researches. this direction in passing through the orifice, and thus the re- sistance experienced by the particles coming from the prominent corners, produces that greater change of form already described. 78. The peculiar form of the upper part, zyooxz,, fig. 19, of the jet from a square aperture is also explained by the influence of pressure, as above elucidated ($§ 65 to 68). The particles of water coming from the corners of the square exert a greater pressure on the sections immediately beneath the aperture than the others; hence the corners are blunted, as is seen in the section «. In passing from this to the following section, the blunt corners exert a greater pressure than the sides of the square. For this reason the corners become more and more blunt in the lower sections, and the sides of the square become smaller. Hence on the jet are formed the triangular surfaces xyo, fig. 19, which are sometimes vertical; but some~ times, when a greater pressure is exerted by the blunt corners on the interior of the jet, appear pressed outwards, so that the point o is more prominent than the side of the aperture above it. With a regular efflux, however, the four points o lie in the same horizontal plane. The section in this plane is almost square, although its sides are generally bent inwards; the edges o cor- respond, however, to the centres of the sides of the aperture, a phznomenon which has been frequently observed, but never before explained. The somewhat curved surfaces woo, yoo, &c. are con- tinued to 2z, By the pressure which is exerted in these on the interior of the jet, the masses of water which form the surfaces Opq, 0, Pp» &e. are forced out, and the same action is produced as with a cruciform aperture, § 61, or as if four jets coming from the corners of the square were to move towards each other. 74. If the motion of the several particles of water be consi- dered, it follows directly from the explanation of the origin of the jet just given, § 65 et seq., that scarcely one of them moves in a vertical plane. It is manifest that in that part of the jet where the various surfaces opq, 0,p,7,, &c. are situated, the par- ticles do not remain in the same vertical plane. But even in that part of the jet above the first system of these surfaces, vyoo,z2,, they do not remain in the same vertical plane, with the exception of those particles which come from the middle of the sides of the square; for the parts coming from the prominent places of the aperture press aside those particles opposing resistance to them. This lateral motion may be clearly perceived in the surfaces yoo,z, for the particles are seen moving from y, and from the places situated under y in the line yz above oo, towards o and 9,. Similarly it is evident, that in the surfaces zyo the particles con- verge towards 0. These converging and diverging motions of the particles have already been observed by Poncelet and Les- Prof. Magnus’s Hydraulic Researches. 185 bros*, who, however, as observed above, have not stated how these motions of the particles arise. The explanation given of the origin of the jet proves their necessity, so that these motions may be taken as a proof of the correctness of the explanation. 75. The forms of jets from triangular, pentagonal, hexagonal, and all other regular polygonal apertures, may be explained in an exactly similar manner to those from a quadratic aperture. The form of a triangular jet is given in fig. 21. The surfaces of the first system, opg, &c., are also in this at right angles to the sides of the aperture vy, &c., and the form of the part between the aperture and this first system is intelligible enough after what has been said, § 73 et seg., of a quadratic aperture. In pentagonal and hexagonal apertures the several surfaces opq are still distinctly perceptible. With all these apertures, a second and third system of surfaces, and often more, are visible. The surfaces of each system bisect, as in the triangular and quadratic apertures, the angles between the surfaces of the pre- ceding system; but the more corners the aperture has, the less prominent are the surfaces. If the number of the corners is great, the surfaces of a system lie very near each other, and they then appear like a dilatation of the jet uniformly disposed around it. Jet from a circular aperture. 76. Circular jets deport themselves differently to those coming from angular apertures. After what has been published by Savart, it might have been supposed that the dilatations just mentioned, which the surfaces belonging to a system in a poly- gonal jet form, would also occur in circular jets. But this is not the case. For such a jet exhibits no dilatations if it issues from perfectly circular apertures; if all hindrances in the interior of the vessel are avoided, if no rotatory or other motion occurs, there is formed under these circumstances a con- nected mass of considerable length, without any, or at all events with so inconsiderable dilatations, that they are scarcely per- ceptible. From an aperture 12 millims. in diameter, and with a pressure of 0™25, I have obtained a jet which fell vertically 2™-5 without any dilatations. It would doubtless have re- tained its connectedness to a still greater depth had it been pos- sible to fix the vessel firmly enough at a greater height. The depth to which the jet remains continuous, is changed as well by the pressure as by the diameter of the aperture. The smaller this is, the smaller is the distance to which the jet retains its continuity ; and this distance is also smaller the less the pres- sure under which the efflux takes place. * Expériences Hydrauliques, p. 151. Phil. Mag. 8. 4. Vol, 11. No. 71. March 1856. O 186 Prof. Magnus’s Hydraulic Researches. The aspect of such a continuous jet, 2™5 long, is very beautiful. It appears like a perfectly turned solid mass of the whitest glass, for there is not the slightest motion perceptible. 77. That in a jet issuing from a circular orifice there are no dilatations perceptible in the immediate neighbourhood of the orifice, is evident from the explanation just given of the form of jets issuing from a quadratic or polygonal aperture. For since im a circular jet the resistance in all directions is the same, and all parts of the liquid pass over the edge of the orifice with equal velocity, the resistance for all parts is the same, and no part of the jet can be pushed more forward than another. 78. But if the afflux of the liquid does not take place with equal velocity from all sides of the vessel, either because the edge of the aperture is not quite smooth, or because the aperture is too near one wall of the vessel, or because it has been made ina wall of the vessel, and its diameter is so great that the liquid flows out at the lower edge with a greater velocity than at the upper one, or because other hindrances occur, then dilatations are formed even in acircular jet in the immediate neighbourhood of the aperture. By placing a piece of sheet-metal at the bottom of the vessel near the orifice they may be perceived. 79. These dilatations or ventral segments are, however, not to be mistaken for the ventral segments which Savart has de- scribed*. The latter, to which I shall afterwards, § 81, return, are formed only when the liquid has ceased to be continuous ; while the dilatations are formed at a very small distance from the aperture, where the jet is still perfectly continuous. These ventral segments differ from those of Savart, in so far that the latter form surfaces of rotation, while the ventral segments under notice have no circular sections. 80. If the water be allowed to issue from a circular aperture tranquilly and without any perceptible disturbance, but without using the tranquilizer, $38, the rotation, mentioned at § 37, occurs in the vessel after some time, and the jet assumes a small spiral form, which is first perceived at the parts most distant from the efflux orifice. This is of course present in the upper part of the jet, but it is not visible: only after some time, when it is toler- ably marked in the lower part, is it perceptible above, and thus it has the appearance of spreading from below upwards. After some time the whole jet appears like a twisted rope, and although it issues from a circular orifice, it is quite similar to the jet from an elongated quadrangular orifice, § 51, fig. 16 a and 3, except- ing that it is not deflected like that, but falls down vertically. After what has been said, § 52 to § 58, on the origin of such spirally formed motions, this needs no further explanation. Every * Annales de Chimie et de Physique, 2nd series, vol. liii. p. 337. Prof. Magnus’s Hydraulic Researches. 187 motion which is communicated to the vessel causes a change in the form of the jet. Sometimes the spiral motion in jets issuing from circular orifices is so violent that they separate into two or more jets, which then continue their way separately, just as with the jet from an elongated quadrangular orifice, § 58. Maximum of contraction. 81. In perfectly regular jets from circular orifices there is no maximum of contraction. Although their diameter decreases most rapidly in the neighbourhood of the orifice, it also continues to decrease until the jet has lost its continuity. 82. Newton* first maintained that the quantity of water flow- ing out was regulated by the contraction of the jet, and he mea- sured this contraction ; but I could not find a decided explana- tion of the contraction of a jet (contractio vene), either in New- ton’s work, or in any others on the same subject. Since it is a question of a determinate plane, we must pre- suppose, and many have thus understood the expression, that a section of the jet is meant, which is a minimum, 2. e. smaller than all other sections ; so that the jet, after it has contracted to this minimum, assumes either larger sections, or at any rate contracts no more, Such a smallest section is seen in all jets which present dila- tations in their continuous part ; hence it is present in all which do not issue from cireular orifices ; and even in these, when the afflux to the orifice does not occur with equal regularity from all sides. But in circular jets, which issue regularly from a hori- zontal aperture, there is no maximum of contraction perceptible, but, as before remarked, § 78, their diameter continually de- creases till they cease to form a continuous mass. F. Savart+ mentions this in his description of jets. 83. It is remarkable that measurements have been made, principally of circular jets, not only by Newton{, but also by the greater number of those who have measured the contraction of the jet. Probably they have never used quite regular circular jets, or by contraction they have understood something quite different ; for, as already mentioned, § 78, the diameter of perfectly circular jets diminishes most rapidly near the efflux orifice, obviously in consequence of the horizontal motion by which the particles of liquid in the vessel reach the orifice. After this decrease has commenced, the diameter is smaller, because the velocity of the falling liquid is greater. This last decrease in the diameter is * Principia Philos. Natur., Prop. XXXVI. + Annales de Chimie et de Physique, 2nd series, vol. liii, p, 338, t Principia Philos. Nat., Frop. XXXVI. 2 188 Prof. Magnus’s Hydraulic Researches. far smaller than the first, and by many it. appears to have been quite neglected, for they considered the jet to be cylindrical after experiencing the first contraction; at least Bossut says*, “at the point of contraction the jet assumes a prismatic form and retains it for a short distance.” It scarcely needs mention, how difficult it is to determine where the part which we consider as cylindrical begins, and how little we are in a position to measure its diameter with accuracy. We cannot, therefore, in a strict sense of the word, speak of a maximum of contraction in cir- cular jets. Savart’s ventral segments. 84. If, whilst a jet of water is issuing from a circular orifice quite tranquilly and without any dilatations, an agitation lasting only a short time be made, by stamping for instance on the ground, the jet separates close to the orifice and carries an air- bubble down with it. In thin jets this separation is not noticed, but when the diameter of the jet is 12 millims. or more, it is seen very distinctly. It arises evidently from the vibration which the vessel assumes, and hence the liquid in the orifice assumes for a moment a motion which is opposed to that with which the liquid would have passed out of the orifice. If, instead of this agitation, a tone of some duration be produced in the neighbour- hood of the vessel, it will also be set in vibrations. They are not so strong as those produced by agitation, so that the jet does not separate; but the liquid in it is moved by the vibration partly in a direction opposed to that of its efflux, and partly in various other directions. Hence the connexion of the parts is smaller, the jet does not form in its entire length a continuous mass, and Savart’s ventral segments are produced at those places where it begins to separate. 85. If the jet issues tranquilly from a circular orifice, and if all vibrations are avoided, no, or at any rate no perceptible ven- tral segments are formed, even where the mass ceases to be con- tinuous ; for the liquid moves in the jet with greater velocity the longer it falls. Hence the jet becomes thinner, until the velocity in any one section is so much greater than that in the preceding, that the difference becomes too great for the force of cohesion with which the strata are held together. When the lowest stra- tum has separated, the separated mass moves with the velocity it has acquired by the fall, and no ventral segments are formed. 86. If vibrations are communicated to the jet after it has left the orifice, the liquid in it separates, not so much on account of the velocity which the lower sections have attained, as that a * Lehrbegriff der Hydrodynamik, translated by Langsdorff, vol. ii. § 446. p: 19. Prof. Magnus’s Hydraulic Researches. 189 stratum is moved upwards by the vibration, or more correctly, hindered in its descent, while the strata immediately below are either moved forward by the vibration or accelerated in their motion. Hence the separation takes place before the separated liquid has attained that great velocity, and then the ventral seg- ments are formed which Savart has described. This mode of separation may, under proper conditions, take place when the jet moves upwards as well as when it moves downwards, or when it moves at any angle to the horizon. 87. When a jet of water reaches the ground a noise is produced, which is sufficient, if particular precautions be not taken, to pro- duce the Savart’s segments in circular jets. If the jet be allowed to fall into a vessel made of sheet-metal, it produces a tone which still more promotes the formation of segments. If the vessel is large, and the bottom only slightly, or not at all covered with water, the tone is very deep and strong, and the ventral segments are then more prominent*. These are particularly strong when the oscillations of this vessel can be completely communicated to those of the upper one, either by joinmg them on the stand, or by connecting them by means of some substance which easily transmits motion. 88. Just as the continuity of the jet is diminished by the vibration of the vessel, it is also impaired when, by removing the tranquilizer, § 38, the jet assumes the spiral shape mentioned in § 80. Savart’s ventral segments generally make their appear- ance without any tone or noise being produced in the neighbour- hood, soon after the first traces of spiral motion have been per- ceived at some distance from the efflux orifice. The segments vanish, however, when the tranquilizer is put again in its place, because then the spiral-shaped motion in the jet ceases. On the penetration of air-bubbles in a liquid. 89. Jets falling into a vessel which already contains some of the same liquid, cause, with but few exceptions, air to penetrate into the liquid. I made experiments several years ago, in order to find out under what conditions this penetration takes place. These experiments were communicated to the Berlin Academy of Sciences as long ago as the 8th of December, 1851, but their publication was deferred because they stand in intimate con- nexion with these experiments on the nature of the liquid jet. * The changes which the tone undergoes are very surprising. The strong deep tone often changes suddenly into a much higher one, and this changes suddenly again. I have not further examined the reasons of these changes. They probably arise from the changes in the vibration of the metallic vessel when the water in it increases; the vessel out of which the water flows is set into other vibrations, and by this the form of the jet and its action on the lower vessel are changed. 190 Prof. Magnus’s Hydraulic Researches. 90. If a solid body which has a greater specific gravity than water be laid on the surface of water, the latter is pressed aside, but unites again immediately over the body. But if the body falls from some height into the water, the latter receives at the place where it is first met a strong push, which moves it further on one side than would be necessary to make room for the pushing body. This process is repeated in the strata immediately below the surface, and in this way a cavity is formed in the water which has a greater section than the falling body. But since the mo- mentum of the latter in its further motion is lessened by the resistance which it experiences, at a greater depth it moves the water less on one side. Hence the cavity at a greater depth is narrower, until at length the momentum which the body has received by its free fall on the surface is destroyed, and its further sinking occurs just as if it had been tranquilly laid on the water, which is now only so much moved aside as its mag- nitude necessitates. 91. If the falling body, on meeting the water, possesses any considerable moving force, the cavity extends so far down that the water meets on the surface and closes before its formation below is completed. Hence air is enclosed, which afterwards reaches the surface in the form of a bubble. 92. It is scarcely necessary to mention, that bubbles are formed in exactly the same way if, instead of a solid body, single drops of water fall into the water. The cup-shaped cavity which drops of water produce can be distinctly observed by letting them fall into water which is con- tained in a glass vessel, and looking at the superior stratum of liquid from the side through the water. 93. It might be believed, that a cavity whose section is greater than that of the falling drop or solid body, was not necessary for the production of air-bubbles ; for if the water did not separate further than the section of the body requires, air would also be enclosed, if this body only moved quickly enough so that it might have reached a sufficient depth below the surface before the water above had joined. It is easy to show; that, if this were the case, the quantity of air would be far too small to produce the bubbles which are actually observed. For if small solid bodies, for instance shot, be let fall into a vessel which contains a stratum of water 2 centims. high, then if the shot fall from a height of 1™°25, air-bubbles are obtained whose contents are many times greater than those of a cylinder of the height of the water and the diameter of the fallmg shot. This phzno- menon is more surprising when peas, instead of shot, are used. It is only necessary to think of the great bubbles which are formed by rain-drops falling almost vertically into shallow masses Prof. Magnus’s Hydraulic Researches. 191 of water, to see that these bubbles must be formed from a cavity whose magnitude is far greater than that of the drops. 94. The greater the force with which the falling body meets the water, the greater is the cavity, and hence the bubble result- ing therefrom. If solid bodies, a$ peas or shot, fall from a few inches’ height into the water, very small air-bubbles are obtained ; these are much larger when the bodies fall from the height of a few feet. 95. But even if the water-drops fall into the water from a height of many feet, the air-bubbles produced go only to a very small depth, at most a few inches below the surface. Even if, instead of water-drops, peas be used, the result is quite similar ; there remains then a small air-bubble adhering to almost every pea, which goes with it slowly to the bottom. 96. But if leaden bullets as large as, or larger than, shot be let fall into the water, the bubbles are seen to reach to a greater depth. If musket-bullets be used for this experiment, and if they be allowed to fall into glass vessels two or three feet deep, then along the whole of the way through which the bullet passes nm the liquid, the air is seen to escape in bubbles, the last and largest of which is separated when the bullet strikes against the bottom. 97. Just as lead causes the penetration of air toa great depth, so can this be effected by single separated masses of water when they fall on the water in rapid succession; for each successive drop pushes anew, producing a stronger motion, and hence one extending deeper. That is the reason why air-bubbles formed by single drops of water only reach to a considerable depth when they form a continuous, or almost continuous jet. 98. For even when a jet is entirely continuous, it carries with it air-bubbles downwards. In a previous treatise, ‘‘On the Motion of Liquids*,” I have mentioned in § 18 that a cavity could be perceived when such a continuous jet fell vertically on the surface of the water. ‘The first origin of this is doubtless similar to that of the falling of a solid body into water, but its continuance has an entirely different reason ; for so long as the cavity is there, the jet only meets the water at the deepest part of it. It is there pressed towards the side; is not, however, moved in a horizontal direction, but is pressed upwards by the resistance which the water present offers. And since this action of the resistance is repeated throughout the whole distance, the motion becomes curvilinear, and there is formed a curved surface or cup-shaped cavity. 99. From this explanation, it is shown that this cup-shaped cavity ean ouly be formed under a certain velocity of the jet ; for if the velocity be small, the water is moved aside with only * Poggendortf’s Annalen, vol. Ixxx. p.1. Phils Mag. for January 1851. 192 Prof. Magnus’s Hydraulic Researches. moderate force, and only deviates as far as the section of the falling jet requires. The water can then draw itself up the jet, as Prof. Tyndall* has observed, just as im aglassrod. But if a sufficiently strong pressure be employed, and the cup-shaped cavity is produced, it is manifest that it can only remain so long unchanged as the water in which it is produced does not disturb its form by other motion. As soon as this is the case, the air which it encloses is carried down with the water into the liquid. 100. If a water-jet from a perfectly circular aperture 3 millims. in diameter, and under a pressure of a column of water 2 or 3 metres high, be allowed to fall vertically on the smooth surface of water contained in a vessel 0™6 in height and width, and if care be taken that the jet meets the surface (which must be only a few centimetres from the efflux orifice) when the former is quite clear and transparent, the above-mentioned cavity can be distinctly, and for some time seen. But after some time the water in the vessel into which the jet falls always begins to move. This motion is very perceptible in particles of dust or very fine bubbles which float on the surface. They are seen to move slowly in a circle about the place where the jet meets the water. This rotation becomes more rapid, and at a certain velo- city a cavity is formed which is drawn downwards in the liquid in screw fashion, and carries with it innumerable small air-bubbles. 101. The formation of this screw-shaped cavity is promoted by setting in rotation, in any other manner, the hquid into which the jet falls. If this be done about the place where the jet meets the surface, the cavity winds like a screw either to the right or left, according as the rotation has the one or the other direction. 102. As this screw-shaped cavity can be formed by setting the water in rotation, so it can be stopped by preventing the rotation. Ifa solid plane, as a thin board or a metal sheet, be held vertically in the water into which the jet falls, so that one of its edges is parallel to, but at a small distance from, the axis of the jet, the screw-shaped cavity is not formed, or if already formed, it dis- appears. 103. In order to be able to produce or stop this rotation more certainly, I made use of the tranquilizer described in § 38. If this be so placed in the water that the jet falls inside the space abcdfg, fig. 13, the rotation is prevented, and no screw-shaped cavity is formed. But if the tranquilizer be rapidly turned about the prolongation of the jet, and the water be thus set in rotation, the cavity is formed immediately, and lasts as long as the rota- tion, but disappears as soon as the apparatus is held firm. 104. If, instead of the tranquilizer, the water be moved in any other way, it is only seldom that it rotates exactly about the pro- * Phil. Mag. S, 4. vol. i. p. 105. Prof. Magnus’s Hydraulic Researches. 193 longation of the jet. It is generally so moved that it has no determinate axis of rotation. The cavity just formed is seen to move with the water from its place of formation, so that it is observed on the surface at the same time that it swims in the water. This phenomenon is particularly seen when the water is only a few inches deep. If the water be moved quite irregularly, the cavity is seldom produced. 105. It is easy to see how a screw-formed cavity is produced by a rotation of the water. In consequence of the centrifugal force, the particles move away from the axis of rotation in all directions ; but they experience a greater resistance in the deeper strata, where the pressure of the water is greater. Hence their distance from the axis of rotation is less in the lower strata, and diminishes with the depth. In this manner a funnel-shaped space is formed, in which the centrifugal force acts in an oppo- site direction to the hydrostatic pressure. But since, in the dif- ferent strata, the rotation does not take place readily about the same axis and with the same velocity, the cavity assumes a screw shape. 106. If water which does not rotate, but is quite tranquil, is met by a jet, it produces, as was mentioned, § 100, a rotation after some time. This is not produced as long as the jet is quite regular, not even if a jet from a square or other polygonal orifice be used. But the slightest irregularity in the jet, and this is much more the case in jets from angular than from circular apertures, sets the water near the place where the jet meets it in irregular motion. The resultants of the motions of the indi- vidual parts do not go through the same point, and hence a rotation commences which rapidly increases when it has once begun. It is scarcely necessary to mention how easily such an irregularity occurs in circular jets, or rather how difficult it is to avoid them. Any motion communicated either to the vessel from which the water flows, or to that into which it flows, is sufficient to produce it, for the motions produced are easily communicated from the one to the other. 107. If the jet meets the spiral-shaped windings of such a cavity, which is changed by a motion of the surrounding water, the wall of the cavity is hit by the jet, air is enclosed and carried down with the water which streams in. The same occurs if the cavity changes its form or position by an alteration in the nature of the jet. 108. If the water which supplies the jet be set in vibra- tions, the jet assumes, even if it comes from a circular aperture, the round form mentioned, § 80, and then air-bubbles penetrate into the water very easily. The force with which this happens 194. Prof. Magnus’s Hydraulic Researches. depends on the strength of the spiral winding of the jet, as well as on the pressure with which it acts on the liquid. 109. If an aperture of 3 millims. diameter in a thin wall be so used that the pressure under which the water issues can be increased at pleasure to the pressure of a column of water 2™'5 high, then if the jet under a small pressure meets the surface at the distance of a few centimetres from the orifice, no bubbles penetrate into the water, even if it be set in motion or rotation in any other manner; but if the pressure is increased, the jet changes, the spiral-shaped cavity is formed, and air-bubbles penetrate into the liquid. If the rotation of the water be then prevented by means of the tranquilizer, no air-bubbles penetrate, even under the application of a pressure of 2™5. But if the efflux aperture be changed for a wider one, for instance of 9 mil- lims. diameter, the jet sets the water in such a whirlpool-shaped motion that the tranquilizer has no effect, and it is impossible to prevent the penetration of air-bubbles. 110. If the water be met by the jet when it is no longer con- tinuous, air always penetrates ; but since the place where the jet ceases to be continuous depends on the vibrations communicated to the vessel from which it flows (§ 86), and since such vibra- tions may be produced by the most insignificant circumstances, it may easily occur, that, while everything seems unchanged, air-bubbles suddenly penetrate. I will mention an experiment very easy to perform, but which is very surprising. 111. If from a vessel of moderate size (that used was about 0™-3 in diameter and height, and stood upon a not very firm frame) a jet be allowed to flow through an orifice 3 millims. in diameter, and if it be caught in a glass held in the hand, the bubbles are first seen, if the glass is gradually lowered, where the jet ceages to be continuous. If the glass be held at a some- what higher place where no air-bubbles penetrate, and if, when the first glass is full, the excess of water be caught iu a second, likewise held in the hand, no air-bubbles are seen to penetrate into the water of the first glass. If the water from the second be let fall into a tin vessel standing on the ground, a noise is produced, and air-bubbles penetrate into the first glass. Hence by an easy movement of the second glass, which is quite sepa- rated from every other glass, air can be made to penetrate or not at pleasure into the first, which remains fixed in its place. It is very surprising to see bubbles making their appearance in the first glass as soon as a small quantity of water falls into the lowest tin vessel, and disappearing again as soon as the falling of the water ceases. Prof. Magnus’s Hydraulic Researches. 195 Jets which contain air in their interior. 112. Besides the cases already mentioned, in which air pene- trates with the jet into the water, there is one case essentially different from these; for if the water in the vessel from which the jet issues begins to rotate, which easily happens when no tranquilizer is employed, there is formed after some time a fun- nel-shaped cavity. This often draws itself downwards, not only to the efflux orifice, but even, when this is not too small, beyond the orifice into the jet, which hence assumes a peculiar appearance. If it issues from a circular orifice, and is without dilatations, the air often draws itself down in it, changing the jet into a tube, which becomes narrower with increasing di- stance from the aperture; but if the jet possesses dilatations, or spiral-shaped windings, § 80, these appear filled with air, and it has then the appearance of a spiral-formed hollow tube. When the jet issues from a polygonal aperture, air is only drawn in, if it has already assumed a spiral-shaped form in consequence of rotation. This is seldom regular, and becomes more irregular by drawing air in. Hence the form which it assumes is difficult to determine, and it can only be said in general terms to be similar to a spiral hollow jet from a circular orifice. 118. If the hollow jet meets the surface of perfectly tranquil water, the air contained in the jet does not penetrate far below the surface as long’as the motion is quite regular; but after a short time the motion becomes irregular, rotation ensues, and now the air goes down in little bubbles to a great depth with the water. 114, After this discussion of the different conditions under which air penetrates into water, the so-called water-bellows, which I have discussed in the appendix to a previous treatise **On the Motion of Liquids,” needs no further explanation. For it is manifest, either that the air, by a funnel-shaped motion of the water, gets into the jet, and is carried down with this into the water of the pipes, or that the jet, without containing air, is so set in motion where it reaches the water, that air is enclosed and carried down with the water rushing in. 115. Looking at the preceding investigations, it will be con- ceded that they give a clearer insight into the phenomena of efflux. The remarkable forms of jets are explained on the simple laws of motion, of resistance, and of cohesion. The influence which a motion in the vessel from which the jet issues exercises upon its form, and the manner in which this influence is exerted over the whole length of the jet, are so far explained that it is possible to produce at pleasure all the different forms of jet. And not only this, but the reverse also: to determine from the 196 Mr. R. P. Greg on the Crystalline Form of Rhodonite. form of the jet its origin; and to judge whether any and, if any, what irregularities are in the vessel. The conditions also for the penetration of air into the jet are laid down; the con- traction of the jet is fully discussed, and the differences in its form from a square or a circular aperture are shown; so that I believe I may assume that these investigations will not be with- out success in determining the velocity of efflux. XXIV. On the Crystalline Form of Rhodonite. By R. P. Gree, Esq., F.G.S.* GILICIFEROUS Oxide of Manganese, or Rhodonite, is de- scribed by W. Phillips (see his ‘ Mineralogy,’ 4th edition, published by R. Allan) as having for its primary form a doubly oblique prism, with cleavage apparent in two directions perpen- dicular to each other, that parallel to P highly perfect; say MT=121° 0', TP=112° 30’, MP=93° to 94°. Dufrenoy, in his ‘ Mineralogy,’ states that this mineral has four cleavages ; two of about 87:5, and two others perpendicular to these, and that it has an oblique rhombic prism for its primary. Rose, Dana, and Brooke and Miller in their recent edition of Phillips’s ‘ Mineralogy,’ agree in stating that rhodonite is isor- morphous with augite, having three cleavages: viz. a, perfect ; b, less perfect ; m, imperfect ; ab = 90 O mm= 92 54 ma =136 27 be = 90 O That rhodonite is isomorphous with augite has perhaps been too hastily assumed to be the case, arising from the coincidence of each mineral giving cleavages of about 87° 5’, as well as from a similarity in their chemical formula; rhodonite having for its formula 3MnO 2S8i0°, where part of the MnO is replaced by FeO,ZnO,CaO,MgO; while augite is represented by 3RO2Si0°, where RO consists essentially of MgO and FeO. Hitherto perfect crystals of rhodonite, having also brilliant faces, have been quite a desideratum among mineralogists. I have, however, very lately received specimens from the Paisberg iron mine near Phillipstadt, in Sweden, on which are implanted some very perfect and brilliant crystals, from the examination of which I have been enabled, I think, without doubt to make out its true form and principal cleavages, and to give correct angles. The following form, as given in the figure, I have observed to * Communicated by the Author. Dr. Atkinson’s Chemical Notices from Foreign Journals. 197 bea constant one in the Paisberg crystals; the face's is frequently, as well as m, a predominant one :— mt = 87 20 A tp = 86 10 mp =110 40* me =136 20 my! =188 20 Cy ms =148 42 me = 86 35 te =142 30 Ve Cleavage highly perfect, parallel to m and p, less soto¢. From this it would appear that rhodonite, or manganspath, belongs to the anorthic system, having, as W. Phillips described it, a doubly oblique prism for its primary; it cannot therefore be isomor- phous with augite, though having a similar formula. That rhodo- nite has any regular cleavage giving an angle of 90°, appears to me to be very problematical ; the figure and angles I have now given may, however, afford some key or explanation to the various and discordant descriptions hitherto published respecting the form and cleavages of this mineral. aS. —— — —aeannqnnss eee XXV. Chemical Notices from Foreign Journals. By HE. Arxrnson, Ph.D. [Under this title it is proposed to give, from time to time, abstracts of the more important chemical contributions to the foreign scientific journals. The chemist will not find in them a substitute for the use of the original memoirs or their transla- tions, as they will merely give the final results, and not detailed descriptions of the processes. Their object is to afford to the general scientific reader an idea of the progress and direction of the labours of foreign chemists. | TEBIG’S Annalen der Chemie und Pharmacie for September contains two important papers by Liebig. The first of these is “On the Constitution of the Compounds of Mellone.” The author’s formula for these compounds had been called in question by Gerhardt, who assumed in them a radical hydro- mellone. Liebig’s earlier formula for the mellone metals was * This angle appears to vary slightly measured on cleavage faces, viz. from 110° 30’ to 112° Myr W. Phillips giving 112° 30’; the crystalline variety from Paisberg, 110° 30! to 111° 0'; and that from Franklin, New Jersey (show- ing also occasionally the faces m, e, t) 111° 30’. 198 Liebig on the Constitution of the Compounds of Mellone. Cl? M? N8, and Gerhardt represented them as C!? H M? N°, and the radical hydromellone as C!? H? N9, The latter view is quite incorrect. After a careful study, the author had found that im the formation of mellonide of potassium the materials, sulphur and dried ferrocyanide of potassium, united to form sulphocyanide of iron, and that the mellonide of potassium resulted from the decomposition of this body at a very high temperature. The formation, under these circum- stances, of a hydrogen compound from materials which were free from it was impossible. Further, in the analysis of hydrogen compounds, there is always an excess of water found, but in all the very careful and accurate analyses of mellone compounds, there had never been more than half the quantity of hydrogen found which Gerhardt’s formula requires. Some criticism is devoted to Gerhardt’s views of the products obtaimed by Henne- berg in the decomposition of mellonide of potassium by alkalies, and in the other compounds derived from mellone. Liebig charges Gerhardt with a tendency to reject formule derived from accurate experiments on insufficient grounds, merely because they do not favour his personal opinions. Henneberg’s investigation of the decomposition of mellonide of potassium led the author to resume the study of the subject. If the author’s old formula for mellonide of potassium were correct, it must give on decomposition, along with other pro- ducts, formic acid. But careful experiments showed that under no circumstances was this acid a product of decomposition, and the old formula must be rejected. After much investigation results were obtained which led to the unexpected formula C8 N!8 H® for hydromellonic acid. The acid was obtained by precipitating corrosive sublimate with mellonide of potassium, dissolving the mellonide of mercury formed in hydrocyanic acid, precipitating the mercury by sul- phuretted hydrogen, filtermg, and expelling the hydrocyanic acid by gentle heat. In the acid either one or all the equivalents of hydrogen are replaceable by metals. As mellonide of potassium is the best source for the other compounds, the author devoted a good deal of attention to its preparation, and goes into the particulars of the different processes in some detail. A great many analyses were made of the different salts. There are three potash salts, a neutral one, whose formula is C!8 N83 K3+10HO ; an acid insoluble salt, C18 N18 K?H, and an acid soluble one, C!8 N!3K H?+6HO. The silver salt has the formula C!® Ag? N18. Numerous accurate analyses of the dry salt, effectually disproved the idea of Gerhardt that the radical contains hydrogen. Liebig on a new Cyanic Acid. 199 Henneberg found that mellonide of potassium treated by strong potash gave cyameluric acid, for which he proposed two formulas, one of which contained an equivalent of hydrogen. Gerhardt assumed this formula to be correct, and found in the production of cyamelurie acid an objection to Liebig’s formula for mellone. The analyses which Liebig made, gave in no case more than one-third the quantity of water which an equivalent of hydrogen in the radical requires. The formula of the hydrated acid is C}2 N7 08 H3, and of its salts C!2N70°M3%. Gerhardt had assumed C!2 N7 06 H¢ to be the formula for the anhydrous acid, and for the salts C!? N7 O° H M*. Liebig’s second paper is “ On a new Cyanic Acid.” When fulminate of mercury is boiled for a long time in water, it changes its colour and crystalline structure, being converted into a greenish-brown powder, and loses, in a great measure, its fulmi- nating properties. In this process a new acid is formed, which Liebig calls fulminuric acid. It stands in the same relation to fulminic acid as cyanuric acid to cyanic acid. But while cyan- uric acid is tribasic, this is monobasic, that is, saturates one equivalent of base. The formula of the acid dried at 100°C. is C® N? H3 0%, and its salts contain in the place of one equiv. H an equivalent of metal. Its formula is identical with dry cyan- uric acid, but the properties of the two acids are quite distinct. He gives a new process for preparing fulminate of mercury, which affords it pure and in large quantity. It only differs from the process usually adopted in the proportions of the ma- terials, and in the manipulatory details. Fulminurate of ammonia forms brilliant white crystals which have a refractive and dispersive power equal to that of bisulphide of carbon. It also exhibits the phenomena of double refraction, The potash salt has the same properties. Besides these, the baryta, silver, lime, magnesia and lithia salts were investigated. Simultaneous with, if not prior to the appearance of Liebig’s paper, a communication had been made to the Bulletin de St. Pétersbourg by M. Schiskoff, on isocyanuric acid. This acid is identical with the fulminuric acid, and is prepared by the same process. Schiskoff has gone into the subject at greater length than Liebig. Wicke gives an “ Analysis of some infusorial Earth found in the Lunebourg Heath,” which shows it mainly to consist of silica. The same chemist recommends, in the preparation of molybdate of ammonia from molybdate of lead, that the ore be treated with sulphuretted sulphide of ammonium. A double salt of sulphide of ammonium and sulphide of molybdenum is formed, from which molybdic acid may be easily obtained, 200 Bolley on the Molecular Properties of Zinc. Bolley gives, in a paper “On the Molecular properties of Zinc,” a résumé of less known observations on the physical properties of that metal by other chemists, in addition to experiments of his own. Zine is generally stated to have a crystalline lamellar structure, but the author had found that this was only the case with zine which had been heated to almost a red heat, and then cooled ; while that which had been simply melted and then cooled, had always a small granular structure. The differences in the observations on the spec. grav. of zine are greater than in any other metal ; they vary from 6°86 to 7:2. Bolley ascertained by actual observation on various specimens, that there existed hollow spaces in the interior of the zinc, which were amply suf- ficient to account for these variations. He cast small cylinders of zine about 10 grms. in weight, using every precaution to prevent air being enclosed. These pieces were divided and sub- divided, and the spec. grav. taken, in small pieces until well- agreeing results were obtained. It was found, the smaller the pieces, the higher was the specific gravity. He found that zine which had been heated to melting, and then quickly cooled, had a specific gravity of 7-178, and when slowly cooled 7-145 ; that which had been heated to redness and quickly cooled, of 7-109, and slowly cooled, 7:120. Zine which had been simply melted was comparatively malleable, while that which had been heated to redness was not at allso. The ease with which commercial zine dissolves is ascribed to the presence in it of foreign metals. But even in pure zinc there are differences in the solubility, which arise from the temperatures to which it has been heated. Pure zine was heated to melting, one part poured in cold water, and another poured on a warm plate. Another specimen of the same zinc was heated to redness, and cooled by the same method. It was found that the latter was far more easily dissolved in di- lute acids than the former. He concludes that zinc melted at as low a temperature as possible is distinguished by—1. gra- nular fracture ; 2. probable higher specific gravity ; 3. greater malleability ; 4. less solubility in dilute acids ; while that melted at a higher temperature has—1. crystalline lamellar fracture ; 2. probable less specific gravity ; 3. greater brittleness; and 4. far greater solubility in dilute acids. Bolley suggests that zinc is dimorphous. He finds a support for this idea in the fact that the atomic volume of zinc is very near that of platinum, iridium and palladium, three metals which are dimorphous. In the October Number of the same Journal Schlossberger has two papers on Physiological Chemistry. An investigation of the uterme milk of the Ruminantia showed him that it contains Arppe on the Compounds of Malic Acid. 201 no fibrine or sugar, but a considerable quantity of albumen. The ash was composed of phosphoric acid, lime and the alkalies, with traces of chlorine and oxide of iron. The secretion was found to be the same in the foetus of six and of twenty weeks’ age. The nourishment of the foetus is far poorer in respiratory elements than the nourishment of the new-born animal, but on the other hand, it is richer in plastic elements. The stomach of the foetus was found to contain a liquid con- sisting mostly of liquid mucous matter (Scherer), but in which was no albumen, while the amniotic liquid contained much albumen. The stomach of the foetus has the property of turning milk sour. The same chemist instituted experiments as to whether milk becomes sour by remaining a length of time in the lacteal glands. The experiments were made on a woman, and on a cow. He found that in a normal state of health it did not become sour, even on standing several days. Wohler found that picric acid, treated with protoxide of iron, gave a new acid which he named nitrohematic acid. Pugh has found that this acid is identical with picramie acid, produced by the action of sulphuretted hydrogen on picric acid. De Luna made some experiments on the possibility of substi- tuting for sulphuric acid some of its compounds, in cases where they are to be had cheap. He found this to be the case with the sulphate of magnesia which occurs in the province of Toledo. By heating this body with common salt, hydrochloric acid is evolved, and a residue left, consisting of magnesia and sulphate of soda. From this residue a sulphate of soda of greater purity than the commercial salt is easily prepared. In the above pro- cess, by adding manganese, chlorine may be obtained. Similarly, nitric acid is formed on heating sulphate of mag- nesia and nitrate of soda or potash. In connexion with his investigations on the anilide compounds of tartaric and pyrotartaric acids, Arppe has examined the cor- responding compounds of malic acid. By heating a mixture of 2 equivs. of aniline and 3 equivs. of malic acid, two bodies are formed. The first, malanilide, contains the elements of 1 equiv. aniline and 1 equiv. malic acid minus 2 equiv. water=C!2 H7 N + C* H? 0°—2HO=C'® H8NO%. The second contains the ele- ments of 1 equiv. aniline and 2 equivs. acid minus 4 equivs. water=C'* H7 N+C% H® 0° 4HO=C* H9 NOS, To separate these, the brown mass resulting from the de- composition was treated with water, which dissolved out the malanile. The residue, which is malanilide, after solution in hot alcohol and purification with animal charcoal, crystallizes Phil, Mag, 8. 4. Vol. 11. No. 71, March 1856, 202 Arppe on Nithialine out in thin colourless laminz, which melt at 175°, and sublime at a higher temperature without much decomposition. When malanilide is boiled with concentrated solution of potash, a remarkable change takes place. The greater part of it is taken up by the potash, and at the same time a slimy body is formed which floats on the surface. On the addition of water, the substance, which is partially dissolved in the potash, is separated out as a white insoluble powder. By repeated washing with water this is obtained free from potash, and may then be crystallized from alcohol. The form, analysis and properties of this body prove it to be ¢artanilide, C!* H® NO*. This only differs from malani- lide by containing one atom more of oxygen, but the change produced by the potash is not so simple as the formation of the slimy body shows. The solution of the malanile is slightly evaporated, and any dissolved malanilide is separated by filtration. It is then puri- fied by treatment with animal charcoal and crystallization. It crystallizes easily, and in forms which vary with the concentra- tion of the solution. It melts at 170°C. When boiled with aqueous ammonia it is changed into malanilic acid, which forms with the ammonia a heavy crystalline salt. The acid is separated by treating the ammonia salt with baryta water, and carefully decomposing the baryta salt formed with sulphuric acid. The slightest excess of sulphuric acid reconverts it into malanile. It crystallizes in small grains, expels carbonic acid from its salts, forming with the bases salts which are mostly soluble. Its for- mula is C*? H!! NO§, z. e. 2 equivs. malic acid and 1 equiv. ani- line, minus 2 equivs. water. By heating malanile with nitric acid, the nitro-compound is formed, but so mixed with a resinous matter that it is impossible to separate them. Hofmann and Muspratt found that when dinitrobenzole is treated with sulphuretted hydrogen, paranitraniline is formed with separation of sulphur, C!? (H* NO*) NO*+6HS=C?? (H® NO?) N+4HO+S. In treating dinitrobenzole by ammonia and sulphuretted hydro- gen, Arppe observed that the reaction was more complicated, for in addition to sulphur there separated out hyposulphite of ammonia, anda small quantity of an organic sulphur compound which appears to be a weak base. This body may be obtained by dissolving out the hyposulphite of ammonia with water, and the sulphur with bisulphide of car- bon. It is difficultly soluble in hydrochloric acid, from which it is easily separated by alkalies. It is best purified by treat- ment with excess of strong SO%, which dissolves it, and from Hlasiwetz on two New Bodies obtained from Phloretine. 203 which it is separated by washing with water. It is an amor- phous powder, and does not readily form salts 3; 1s little soluble in alcohol and water, as also in chloroform and zther. It isa product of decomposition of paranitraniline, as Arppe found by direct experiment. A pure specimen prepared in the above manner from paranitraniline gave analytical results which led to the formula C1? H® N?$?20*%. Arppe has named it nithialine. With none of the bases formed by Zinin’s process does this substance, or any analogous one, seem to be produced, except with paranitraniline, as direct experiment showed. Hlasiwetz gives a preliminary account of two new bodies which he has obtained from phloretine. This body is boiled with strong potash, the solution evaporated, and the excess of potash removed by carbonic acid. If the liquid be then further evaporated and treated with alcohol, the potash salt of a new acid is obtained, which he has named phloretic acid. It is easily puri- fied, possessing a great tendency to crystallize. It expels CO? from its salts, uniting with the base to form easily crystallizable salts. Of these the baryta and zinc salts are the most beautiful. It has the same deportment with reagents as lichenic acid. Its formula is C18 H!°0%,HO. It is monobasic; the formula of its salts is C'8 H! O5, MO. The salt residue from which the phloretate of potash had been dissolved out, and the carbonate of potash, contain an interesting neutral body. This is obtained by treating the solution of the residue in water with dilute sulphuric acid, evaporating again and treating the mass with alcohol. The alcoholic solution is again evaporated, and the residue crystallized out of water, Its most remarkable property is its sweetness, from which it has been named phloroglucine. It has the greatest resemblance to orcine, and gives, like it, a bromine substitution compound. The formula of the body crystallized from water is 127710010. for that crystallized from zther, C!2H®O* The bromine com- pound contains 8 equivs. hydrogen, replaced by bromine, and is, in its properties, very similar to bromorcéid. As by the decomposition of phloretine by alkalies no other body is formed, it may be expressed thus :— CH! 00+ KO HO=C!8 H!° O> KO + C!2 HE 08, These bodies stand evidently in a very near relation to the con- stituents of lichens. The same author makes a communication, that direct experi- ments have convinced him that quercitrine and rutinic acid are identical, and have the formula C®* H!8 02!, The discrepancies exhibited by some of the ori of the latter body with the 2 204 Mr. R. W. Pearson on the Determination of Bismuth formula of quercitrine, are explained by the difference in the quantity of water. Buchner recommends for the purification of sulphuric acid from arsenic, the addition of common salt. The hydrochloric acid evolved unites with any arsenious acid present to form terchloride of arsenic, which is easily expelled at a gentle heat. XXVI. On the Determination of Bismuth by Weight and by Volume. By R. Wust Pearson of Manchester*. fi hese method at present employed for the determination of bismuth, consists in treating the solution of the metal with sulphuretted hydrogen, filtering off the precipitated sulphide of bismuth, which, after washing with water, is decomposed by digestion with nitric acid. Nitrate of bismuth is thus formed and sulphur liberated. The sulphur is removed by filtration ; the oxide of bismuth is then precipitated from its solution as carbonate of bismuth: upon the first addition of alkaline car- bonate a considerable quantity of the precipitate produced is redissolved. A. Stromeyert states that the precipitate by car- bonate of alkali is somewhat soluble in excess, but precipitated by caustic alkali. According to L. Laugier, the precipitate is completely soluble in carbonate of ammonia, partly so in car- bonate of soda, and insoluble in carbonate of potash. According to Berzelius§, however, oxide of bismuth is not soluble in car- bonate of ammonia unless phosphoric acid or arsenic acid is pre- sent. Rose|| directs, that to obtain that portion of bismuth which remains in solution after exposure to heat and air, it is necessary to repeat the operations just indicated, 2. e. precipitate as sulphide of bismuth, obtain im solution as nitrate, precipitate as carbonate of bismuth, and expose at a warm temperature to the atmosphere for several hours; after which convert the car- bonate by ignition into oxide of bismuth, in which state weigh. This method, it is evident, is open to a serious objection in the great amount of time consumed in its execution. It is also in- applicable to solutions containing lead or cadmium. Hydro- chloric acid and soluble chlorides must also be absent from the ~ solution. R. H. Brett found that carbonate and oxide of bismuth * Communicated by the Author. + Poggendorff’s Annalen, vol. xxyi. p. 553. { Ann. de Chim. et de Phys. vol, xxxvi. p. 332. § Jahresber. vol. xii. p. 166. || Handb. der Analyt. Chemie, vol. ii. p. 145. “| Phil. Mag. vol, x. p. 95. by Weight and by Volume. 205 recently precipitated, were readily dissolved by chloride of ammo- nium. ‘The same remark applies to the solvent action of chloride of calcium. For the volumetric determination of bismuth no method has hitherto been proposed. To supply the desideratum which thus exists in analysis, viz. a neat, expeditious, and accurate method for the determination of bismuth, I began a series of experi- ments, and in the present communication I have to describe a method which I find to yield satisfactory results. It is based upon the fact that chromic acid, when in liquid contact with bismuth, combines in constant proportions to form an insoluble compound, definite in composition, which is produced under all circumstances. The value of this reaction as the basis for a volumetric mode of analysis, depends upon the characteristic colour of chromic acid and its compounds. TI shall proceed to describe, in the first place, the results of some experiments on the nature of the reactions upon which the method is based ; secondly, notice the estimation of bismuth by weight ; thirdly, its deter- mination by volume; and lastly, adduce the combining ratio of chromic acid and oxide of bismuth. The agent I propose to employ, bichromate of potash, has hitherto never been suggested for that purpose. Chromate of potash, KO, Cr03, precipitates, on addition to so- lutions of most metals, chromates corresponding to the formula MO, CrO#. Bichromate of potash, KO, 2Cr03, combines by double affinity with metallic oxides, as in the case of simple chromate of potash ; the former giving rise to bichromate compounds of the formula MO, 2CrO°, which are, without exception, soluble in water. A peculiar combination of bichromate of potash takes place on its addition to salts of bismuth, viz. the formation of a simple chromate of bismuth, BiO®Cr0O, in which each equivalent of chromic acid is united with one equivalent of oxide of bismuth. I found upon inquiry, that the phenomena of the two equivalents of chromic acid contained in that of bichromate of potash, combining separately with single equivalents of other bodies, took place among the metals with lead and bismuth, and among the alka- line earths with baryta only. I invariably found that acid solu- tions of other bodies remained perfectly clear upon the addition of bichromate of potash. By means of this agent, therefore, bismuth, lead, and baryta may be separated singly, or together, from all other bodies when in solution. I also found that while chromate of baryta is soluble in dilute nitric acid, the chromates of lead and bismuth are comparatively insoluble. The solubility of chromate of bismuth in water, acetic acid, nitric acid, and caustic potash, I determined quantitatively. I immersed a quan- 206 Mr. R. W. Pearson on the Determination of Bismuth tity of well-washed chromate of bismuth in these liquors for twelve hours with frequent agitation of the mixture. To deter- mine the quantity of bismuth dissolved from the tints produced in the several solutions by sulphuretted hydrogen, I prepared dilute standard solutions of nitrate of bismuth, contaming re- spectively known quantities of metallic bismuth. Through each of these solutions I passed sulphuretted hydrogen gas, and in this way obtained “comparison tests” of bismuth. When examined by this method I found the following to be the— Per-centage Solubility of Chromate of Bismuth in water, acetic acid, nitric acid, and potash. In nitric acid, ‘In potash, ‘In water. In aceticacid. sp. gr, 1°03. Sp. gr. 1°33. Chromate of bismuth :00008 -00021 -00024 ‘00016 I found by experiment that the following reaction takes place with bichromate of potash and nitrate of bismuth :— 70,000dth gr. of bismuth: precipitate immediate. 100,000dth , opalescence produced. 150,000dth ves reaction ceases, The characteristic colour of chromic acid is possessed in a remarkable degree by the chromates of potash. Thompson states that one part of chromate of potash may be recognized in 40,000 parts of water. I found that bichromate of potash, when diluted 70,000 times, may be detected by its yellow colour. Estimation of Bismuth by Weight. Previous to precipitating the bismuth in solution, as chromate, it is necessary, as when precipitating by carbonate of ammonia, to ascertain the absence of lead. This may be effected, and, if present, its removal accomplished, by processes to be indicated further on. Nitric acid is the most convenient solvent for ores, &c. of bismuth, taking care to remove any large excess of acid in solution by evaporation. In the absence of lead the solution is supersaturated with bichromate of potash, and the mixture warmed to aggregate the precipitate, which is collected upon a filter and thoroughly washed with water. When washed, the precipitate and filter are dried. The chromate of bismuth may now be estimated after combustion of the filter, or weighed in a filter of known weight ; deducting the latter from the total ob- tained, 1 grain of bismuth is contained in 149074 grain of the chromate of the oxide. Separation of Bismuth from Lead and Baryta.—I include baryta, since on the removal of lead and baryta, bismuth may be by Weight and by Volume. 207 estimated without further manipulation in presence of all other - metals or earths. In systematic analysis we should have to deal with lead only. I have found three methods available for the separation of lead and baryta from bismuth. I. Add to the solution containing, amongst other substances, lead, bismuth, and baryta, dilute sulphuric acid in excess. Sul- phates of baryta and lead will precipitate, the mixture is filtered and the insoluble sulphates drenched with water. The filtrate which contains the bismuth in solution as soluble sulphate is evaporated to expel excess of acid, bichromate of potash is added in excess, and the experiment proceeded with as above. II. If necessary, add a slight excess of nitric acid to the solu- tion containing lead, bismuth, baryta, &c., and precipitate with bichromate of potash ; on filtering, baryta will remain in solution soluble in nitric acid. The precipitated chromates of lead and bismuth are now treated with caustic potash of spec. gray. 1:33. Chromate of lead is readily and completely dissolved by caustic alkali, while chromate of bismuth is comparatively insoluble. By treating the chromates of lead and bismuth with potash, there- fore, we obtain the lead chromate in solution, and by filtration separate it from the bismuth chromate which is insoluble. From the amount of chromate of bismuth obtained, the metal is cal- culated as in I. III. That oxalic acid and neutral oxalates, on addition to so- lutions of bismuth, precipitate oxalate of bismuth, is a fact long known. On adding an excess of oxalic acid with a slight ele- vation of temperature, I have observed that the precipitate pro- duced on the first addition of acid is readily redissolved. This circumstance has not hitherto been noticed, I believe. Oxalate of lead is completely insoluble in excess of acid, even in a hot solution. If, therefore, we supersaturate a solution containing lead and bismuth with oxalic acid, and heat to ebullition, the bismuth remains in solution, while the lead remains as an inso- luble compound. By means of oxalic acid, I find that lead and bismuth may be separated with facility and accuracy. Of these three methods the first is generally applicable, espe- cially when the bismuth alone is to be estimated. The second method is particularly adapted when the lead or baryta are to be estimated also, The third process enables us to separate lead and bismuth with great accuracy. Circumstances will suggest a preference. Separation of Cadmium from Bismuth.—These two metals when associated cannot be separated by any known method with facility. By the use of bichromate of potash, bismuth may be precipitated eit free from cadmium when the two metals are in so- ution. 208 Mr. R. W. Pearson on the Determination of Bismuth Cadmium 38:765 grs. Bismuth 1:244 ... I obtained, taking the cadmium by f Cadmium 3°76517 grs. difference... vA Bismuth 1:24883 ... The bismuth was aaiinaian by volume. Tn a solution containing . Estimation of Bismuth by Volume. The mode of procedure in estimating bismuth by volume analysis is exactly the same as in the now common methods of volumetric determinations. A graduated solution of bichromate of potash is added to a colourless solution of bismuth until the metallic oxide in solution is converted into insoluble chromate of bismuth. By observing the effect of continued addition of the bichromate salt, it is easy to note the rise of a deep yellow colour in the supernatant liquid. This indicates an excess of bichromate of potash, and of course the saturation of the liquid. Preparation of standard solutions.—Bichromate of potash, the agent to be employed, as met with in commerce, is usually con- taminated with sulphate of potash and chloride of potassium. The removal of these and other impurities may be effected by repeated crystallization of the bichromate salt. 7°135 grains ofpure crystallized bichromate of potash areweighed off and dissolved in 1000 grains of water in a large graduated test mixer or other convenient vessel. To avoid subsequent repetition, I shall call this solution the “ bichrome test,” and to distinguish from similar ones affix the letter A—bichrome test A. A second solution, one-tenth the strength of bichrome test A, is prepared in like manner. ‘7135 grain of bichromate of potash dissolved in 1000 grains of water will furnish a solution of such a strength ; I call this solution the “bichrome test B.” A ‘bichrometestC,” one-tenth strength of solution B, is prepared by dissolving 07185 grain of bichromate in 1000 grains of water. These solutions, A, B, and C, will contain chromic acid in 100 grains; equal in solution A to ] grain of metallic bismuth, in solution B to 0-1 grain of bismuth, and in solution C chromic acid equal to ‘01 grain of bismuth. On the correctness of these solutions of course depends the value of any results that may be obtained by their use. In my own experiments I make use of a white glass flask capable of holding about 2000 grains of liquid. As it is neces- sary to keep the solution hot during the experiment, I use a clasp of iron plate with wooden handles; the flask having a rim, it can be slipt round the neck at pleasure. It may be as well to notice the decomposition which takes place on the addition of bichromate of potash to a solution of by Weight and by Volume. 209 bismuth. When bismuth is in solution as nitrate, it may be expressed thus :— 2Bi0?, NO® x KO, 2CrO?= (2Bi0® CrO*) x KO, NO® x NO®. The chromate of bismuth is of a rich yellow colour. In warm solutions it is deposited almost instantly. On the addition of one or two drops of bichromate only, the precipitate diffuses itself throughout the mixture, imparting a yellow milkiness to the whole fluid. Further addition of the bichrome test causes the aggregation of the precipitate; and on the experiment ap- proaching completion, it coagulates speedily, leaving the super- natant liquor perfectly free from any floating particles, in this way affording facility for observing the effect of continued addition of the bichrome test. At the conclusion of the experiment, chromate of bismuth will cease to precipitate, and any further addition of bichrome test will remain in solution, and may be detected by its characteristic colour. An experiment such as just described will occupy about ten minutes. The preceding remarks on the estimation of bismuth apply to colourless solutions only, and for such the method is specially adapted. In commercial analysis, however, it is desirable to analyse ores, alloys, &c. with great rapidity, approximate results only being required. 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Reicu*. ik is still a point of discussion whether the repulsion exercised by a magnetic pole upon a diamagnetic body is the effect of a polarity induced in the latter or not. Mr. Tyndall has recently founded a decision of the question on the consideration, that the diamagnetic repulsion must increase in the simple ratio of the strength of the current if it be simply an action of the magnetic pole upon the unchanged substance of the diamagnetic body ; on the contrary, the increase must be as the square of the strength of the current if the action be due to an excited polarity; just as the action of one magnet upon another, whose magnetism is unchanged by the former, is simply as the current strength, whereas upon a piece of soft iron it is as the square of the mag- netic intensity. Partly by his own experiments, and partly by others previously made by E. Becquerel, Mr. Tyndall has shown that the diamagnetic repulsion augments with the square of the current, which is a new proof of the polarity of a diamagnetic body. Pahoutd not have thought of subjecting these experiments to a corroborative repetition, were I not called upon by M. Mat- teucci to do so, by means of the torsion balance which I had constructed for the determination of the density of the earth; and as the experiments have now been made, I hope that their publication will not be altogether without interest. _ On one end of the torsion balance hangs a sphere of bismuth weighing 48415 grms., surrounded by a cylindrical wooden chamber coated within and without with tinfoil. On a level * From Poggendorff’s Annalen, vol. xevii. p. 283. Phil. Mag. 8. 4. Vol. 11. No. 72. April 1856, S 250 M. F. Reich on Diamagnetic Action. with the centre of this sphere a magnet of known strength was placed at a certain distance from the mass of bismuth, and the consequent repulsion was observed. The arm of the torsion balance remained during the experiment in a state of oscillation, which at the commencement could be produced at will, either by the attraction of a mass of lead, or by the diamagnetic action itself*, From the experiments on the density of the earth, it is known that the oscillating torsion balance never retains for any length of time the same position of equilibrium unchanged, even where all external influences are, as far as we know, preserved constant. These alterations are indeed inconsiderable, but still of a nature calculated to vitiate experiments like the present. Other sources of disturbance the statement of the experiments themselves will reveal. First experiment.—Three square bar-magnets, 496 millims. long and 8°6 millims. thick, characterized by the numbers 4, 5, and 6, were permitted, for the purpose of ascertaining their in- tensity, to act from a distance of 0™:5 upon a compass-needle. The deflection by No. 4 alone was found to be 9° 45'; by Nos. 4 and 5 united, 18° 30’; by Nos.4,5, and 6 united, 23° 24’: the rela- tion of these intensities therefore was as 1 : 1:94.72: 2°5789; and the relation of the squares of the intensities as 1:3°7917:6°6508. These three magnets were brought in succession as close to the sphere of bismuth as possible, that is to say, into contact with the chamber of the torsion balance, and the following num- bers were observed :— Position of equilibrium without magnet . . . 59°200 Position of equilibrium with magnet No.4 . . 55-550 eee ee 4&5 . 48750 * oak 4,5&6 42:425 eee eee 4&5 . 48°075 oe ise 4. . 54575 vee without magnet . . . 57:500 It will be observed here that the position of equilibrium of the balance has sensibly changed; this alteration, however, is nearly proportional to the time. Taking, therefore, the mean, we obtain,— The position of equilibrium without magnet . . 58:3500 The position of equilibrium with magnet No.4 . 55-0625 met ae 4&5 48-4125 won ees 4,5 &6 42°4250 * Der Arm der Torsionswaage blieb dabei immer im Schwingen, was zu Anfang beliebig durch die Attraction einer Bleimasse oder durch die dia- magnetische Eimwirkung selbst hervorgerufen wurde. M. F. Reich on Diamagnetiec Action. 251 The repulsions, therefore, exerted by the respective magnets were as follows :— Mp,.4. 3°2875 divisions of the scale —0-3840=1 we 4&5. 99375 < =1'1608—3-0228 we 4,586. 15-9250 Se =1'8601 =4°8441 The ratio of these repulsions shows decidedly that they increase more speedily than in the simple ratio of the magnetic forces ; but the ratio is still far from that of the squares of the forces. The principal cause of this divergence is, that the distance of the sphere of bismuth from the magnetic pole increased with the repul- sion ; and this augmentation of distance must exert a considerable influence, both because the total distance was but small, and also because, supposing diamagnetic polarity to exist, the repulsion must be in the inverse ratio of the fourth power of the distance. Denoting, therefore, by C the distance of the centre of repulsion in the bismuth sphere in its position of equilibrium without the magnet, from the place occupied by the magnetic pole, then in the case of No. 4 we have the distance equal C +0:3840; with Nos. 4and 5,C+1-:1608; and with Nos. 4,5 and 6, C+1-8601 : the repulsive forces, therefore, are to each other in the ratio 1 __. 37917 © «66508 (C +0:3840)4 * (C+1-1608)? ‘(© +1-8601)7" By setting these ratios equal to the repulsions found by experi- ment, the quantity C, which is not to be found by direct mea- surement, might be determined; for this purpose, however, the experiments are not sufficiently exact. On account of the small- ness of the distance from the sphere of bismuth, the lateral position, and consequently oblique action of the magnets, must make itself felt when three of them are employed. Second eaperiment.—It is plain from the foregoing experi- ments, that it is more advantageous to permit the magnets to act from a greater distance upon the sphere. To obtain a sufficient repulsion under these conditions, the intensity of the magnets must be considerably increased. For this purpose thirty-two bar-magnets, quite similar to those described, were made use of. They were characterized by successive numbers, and lay, when they all acted together, in four horizontal series, each embracing eight bars; so that from Nos. 1 to 8 formed the first quarter, from Nos. 2 to 16 the second quarter, &c. of the surface formed by the ends of the bars: the centre of this surface was in the horizontal line passing through the centre of the sphere at right angles to the arm of the torsion balance, and at a distance of 50 millims. from the chamber. I determined the respective inten- $2 252 M. F. Reich on Diamagnetic Action. sities of the bundles by the deflection of a compass-needle placed at a metre distance, and obtained as follows :— Nos. 1 to 8, a deflection of 11 3, intensity 1 woe, Livse 16, ose 15 45, ... 1:4442 coe 1 wee 24, sea 21 42, wo», 20378 ee 1... S2, ese ot. 0, * oa) Solas The relation of the squares of these intensities is therefore expressed by 1 : 2°0857 : 4°1525 : 68369. The position of equi- librium of the torsion balance was then observed :— Without magnet beginning 57°875 mean 58-9000 end 59925 By Nos. 1 to 8 ae Pee 557250 Fasc, 16 sae Ca ibe 51-9875 1 ... 24 ate poate 465125 de. es beginning BO EOE 39-5725 From this we obtain the repulsion,— Nos. l to 8 8:'1750 divisions =0°3709 millims. =1 pant hey Olen OsO 125 vos =0°8074 er Le cool ton ~ L2:587D 500 = 1:44.70 es =3'9016 sen, leno LOS eOO we = 2°2573 .-- =6:0866 This ratio of the repulsions does not differ more from that of the squares of the magnetic strengths than may be referred to the increase of distance with the repulsion; for assuming for C the not improbable value of 70 millims., we obtain the ratio of the repelling forces to be— 1 __ 2:0857 41525 68369 (70°3709)4 * (70:8074)4 * (71-44.70)4 * (72°2573)4 =1: 2:0347 : 3:9080 : 6°1504, which does not differ from the ratio of the observed repulsions more than may be accounted for by the unavoidable errors of ob- servation. Third experiment.—As the application of an electro-magnet permitted us to hope for more exact results, because, while the position of the magnet remains wholly unchanged, it is m our power to change and measure its strength at pleasure, I placed a round bar of iron, 32 millims. thick and 440 millims. long, contained within a spiral of thick copper wire, horizontally near the sphere of bismuth, so that its nearest end was 67 millims. from the chamber of the torsion balance, and permitted a cur- M. F. Reich on Diamagnetic Action. 253 rent of from 1 to 4 of Daniell’s elements to pass through the spiral. In the circuit a tangent-compass was introduced, and from two fixed points of the circuit a branch current was sent through the multiplier of a sine-compass. The tangent-compass was only divided into single degrees, and admitted therefore of no very accurate measurement of the strength of the current. The sine-compass, constructed by (Ertling of Berlin, is a very per- fect instrument, and permitted of a safe observation of the de- flection of the needle to single minutes. It was, however, found that after the circuit was broken the needle did not return exactly to zero, a consequence of the construction which materially in- terferes with the exactitude of the instrument. The observations gave as follows :— Position of Tangent- Sine-compass. equilibrium. compass. Without current ...) 83-300 0-0 0 0 Lelement 7 .7.-ces | Dana orm cton | Phil. Mag. 8. 4. Vol. 11. No. 72. April 1856. Mean difference =0:000 days. Kingstown Tide, Table F. Difference of observed and calculated times of vanishing at low water, expressed in lunar days. Age of lunar tide = 44 11". | Difference.) Difference. days. | —01 —16 || No. | Difference. | days. 19 | +411 20 =0:3 21 +11 22 +11 23 | —03 24 +0°4 25 +27 26 42:2 27 —03 Mean difference = +-0:004 days. T 266 The Rev. S. Haughton on the Solar and Lunar Srection XI. Diurnal Tide at Courtown. On proceeding to calculate the diurnal tide constants at Cour- town,-I found that it was impossible to construct satisfactorily the diurnal tide at low water. The equinoctial lunar tide at low water was +025 ft. And this value was the same for the spring and autumnal equinoctial tides; but on constructing the tides from the spring equinoctial tide, I could not reconcile it with the autumnal tide, and vice versd. I therefore abandoned the attempt to reconcile theory and observation with respect to the tide at low water at this station, and have only used the lunar equinoctial tide in height, which was found to be accurately the same in amount for both equinoxes. I. Diurnal tide at high water. . Maximum value of lunar tide for positive heights=0°40 ft. . Maximum value of lunar tide for negative heights =0°40 ft. Maximum value of solar tide =0°80 ft. . Diurnal solitidal interval =55 1™. Age of lunar tide = 64 224, Il. Diurnal tide at low water. Maximum value of lunar tide for positive heights =0°25 ft. . Maximum value of lar tide for negative heights =0°25 ft. . Maximum value of solar tide =0°30 ft. ? . Diurnal solitidal interval =55 1™,? . Age of lunar tide =34 124. ? Adding together the first two of each of the preceding results, we find— Range of lunar tide at high water =0°80 ft. Range of lunar tide at low water =0°50 ft. Hence by equation (3), OU 09 09 OU 09 2 é 0:80 cot (m—12,,) = ~~~ ( n) 0:50 or, converting the arc into time, M— tp, = 2" 120; but since m, the moon’s hour-angle at high water expressed in Courtown time, is 74 40™, we obtain 4, =5h 98m m yOu = cot (32°) ; By equation (4), we have max. value of 2M sin2u¢= + (0°80)? + (0°50)? =0'948 ft ; from which we find M=0'719 ft. Also, since the mean value of the solar tide is 0-30 feet, we have max. value of 28 sin 2o=0°600 ft., and therefore S=—0-410 ft. Diurnal Tides of the Coasts of Ireland. 267 Combining the foregoing results, we obtain for the tide con- stants at Courtown,— 1. Lunitidal interval =5 28™. 2. Solitidal interval =5» 1™, 3. Age of lunar tide at high water =6¢ 225. at low water =34125.? . Lunar coefficient =0°719 ft. Solar coefficient =0:410 ft. Ratio of solar to lunar coefficient, DOT or a =0°570. M The theoretical tides at high water were constructed with the foregoing constants, and compared with the observed tides. The results of this comparison are contained in the following Tables. Courtown Tide, Table A. Positive heights at high water for fifteen and a half lunations, commencing 1850, November 74 95 48™, and ending 1851, December 31¢ 142 36™, No. | Observed. |Calculated.| Difference.|| No. | Observed. |Calculated.| Difference. ft ft. ft. ft. ft. ft. ] 0°30 0:25 +005 9 0:43 037 +0:06 2 0:33 0-35 —0-02 10 0°52 0°50 +002 3 0:40 0-45 —0-:05 11 0:47 0:50 —0:03 4 0-31 0:42 —O-11 12 0-34 0°38 — 0:04 5 0°35 0:38 —0:03 13 0-40 0:27 +013 6 | o31 | 032 |-oo01 || 14 | 027 | 023 | +0-04 ih 0:22 020 +0°02 15 0°35 0:35 0:00 8 0:27 0-29 —0-02 Mean difference =-+0:001 ft. Courtown Tide, Table B. Negative heights at high water for fifteen and a half Junations, commencing 1850, November 74.9 48™, and ending 1851, December 314 14» 36™. No. | Observed. |Calculated.|Difference. || No. | Observed. |Calculated.| Difference. ft. ft. ft. ft. ft. ft ] 0°30 0:20 +0°10 9 0°38 0:25 +013 2 0:17 0-22 —0:05 10 0:47 0:39 +0:08 3 0:20 0:28 —0:08 11 0-34 0°45 —O]1 4 0-45 0:45 0-00 12 0:46 0:48 —0:02 5 0:27 0-42 —O15 13 0-50 0:33 +0:17 6 0-23 0°32 —0:09 14 0:30 | 025 +0°05 7 0-17 0-24 | -007 || 15 | 025 | 025 | 0-00 8 0:20 0-17 | +003 16 0:30 ' 0:38 | —0-038 Mean difference = —0:002 ft. T 2. 268 The Rev. S. Haughton on the Solar and Lunar Courtown Tide, Table E. Difference of observed and calculated times of vanishing at high water, expressed in lunar days. Age of lunar tide =64 225, No. | Difference./) No. | Difference.|| No. | Difference. days. days. days. 1 +0°31 12 +156 22 —1:69 2 +0°81 13 —0:94 23 +0:21 3 +011 14 —5°19 24 +041 4 —1:94 15 —179 25 +031 5 | +4081 || 16 | —0-44 || 26 | —2-44 6 | +081 | 17 | 40-41 || 27 | +0-06 7 | +4131 | 18 | 42-31 || 28 | +081 8 —1-44 19 +1-56 29 +131 9 —1:99 20 +1:56 30 +0°81 10 | 4031 || 21 | 40-81 || 31 | +081 11 | 4031 Mean difference = —0-004 days. The agreement between theory and observation shown in the preceding Tables is very satisfactory; and were it not for the difficulties presented in the low water observations, we would consider the tides at Courtown well represented by the theo- retical tides. This discrepancy between theory and observation at Courtown is probably connected with the peculiarities of the Courtown tides, which have been brought to light by the Astro- nomer Royal in his discussion of the semidiurnal tide at this station. Section XII. Diurnal Tide at Dunmore East. Having obtained the values of the diurnal tide for each day at Dunmore, I calculated the constants from them in the usual manner, and found,— I. Diurnal tide at high water. . Maximum value of lunar tide for positive heights =0°22 ft. . Maximum value of lunar tide for negative heights =0°21 ft. Maximum value of solar tide =0°14 ft. . Diurnal solitidal interval =55 15™, Age of lunar tide =54 19. II. Diurnal tide at low water. . Maximum value of lunar tide for positive heights =0°18 ft. . Maximum value of lunar tide for negative heights =0°19 ft. . Maximum value of solar tide =0°14 ft. . Diurnal solitidal interval =5» 15™. . Age of lunar tide =54 144, OUR Co © CU 0 OO Diurnal Tides of the Coasts of Ireland. 269 Adding together the first two of each of the preceding, we Range of lunar tide at high water =0°43 ft. Range of lunar tide at low water =0°37 ft. Hence by equation (3), gts Wor os ans cot (m—t,) = 037 — cot (40° 43") ; or, converting the are into time, M—ly, = 2 48" ; but since m, the moon’s hour-angle at high water expressed in Dunmore time, is 4% 36™, we obtain 4, 12. 48%. By equation (4), we have max. value of 2M sin 2u= V (0°48)?+ (0°37)? =0°567 itis from which we obtain M=0°441 ft. Also, since the mean value of the solar tide is 0°14 feet, we have by equation (5), max. value of 2S sin 20=0°28 ft., and S=0°192 ft. Combining the foregoing results, we obtain for the tide con- stants at Dunmore,— 1. Lunitidal interval =1" 48™. 2. Solitidal interval =55 15™. 3. Age of lunar tide at high water =5¢ 194. at low water =5? 14+. 4. Lunar coefficient =0°441 ft. 5. Solar coefficient =0°192 ft. 6. Ratio of solar to lunar coefficient, or a =0°436. The theoretical tides were constructed with the foregoing tide constants, and compared with the observed tides, with the follow- ing results. 270 The Rey. S. Haughton on the Solar and Lunar Dunmore Tide, Table A. Positive heights at high water for seventeen lunations, commen- cing 1850, September 114 2] 30", and ending 1851, De- cember 20¢ 154 42m, No. Observed. |Calculated.| Difference.|| No. | observed. |Caleulated. Difference. ft. ft. ft. ft. ft. ft. 1 0:17 0-16- | +0-01 10 0:31 0°24 +0:07 2 0°30 0:17 +013 11 0:28 0:30 —0-:02 3 0:20 0:22 —0°02 12 0°30 0°32 — 0:02 4 0°35 0-26 +0:09 13 0:34 0:29 +0:05 5 0:26 0:29 —0-03 || 14 0:12 0:22 —0:10 6 0-13 0:27 -—0-14 15 0-25 0:20 +0:05 7 0-17 0-24 —0:07 || 16 0:28 0-24 +004 8 0-17 0-16 +0-01 17 0-21 0-29 —0:08 9 0-19 0-18 +0°01 Mean difference = —0°001 ft. Dunmore Tide, Table B. Negative heights at high water for seventeen lunations, commen- cing 1850, “September 114 215 30™,and ending 1851, December 920d 15 40m, No. | Observed. (Calculated. Difference. No. | Observed. |Calculated,’ Difference. ft. ft. ft. ft. ft. ft. 1 0-21 0-21 0:00 10 0:27 0 24 +0:08 2 0:27 O16 | +011 11 0:28 0-28 0-00 3 0 23 0-19 +004 12 0:30 0-31 —0-01 4 0:27 0:28 —001 13 0-18 0:28 —0:10 5 0-28 0:29 —0:01 14 0:29 0-28 +001 6 0:08 0:27 —0:19 15 0:29 0-16 +018 7 O11 0:27 —0:16 16 0:26 0:22 +0°04 8 0:20 0-19 +0-01 7 0:32 0-28 +004 9 0:24 0:17 +0:07 Mean difference =0°000 ft. Dunmore Tide, Table C. Positive heights at low water for seventeen lunations, commen- cing 1850, September 134 17" 0™, and ending 1851, Decem- ber 2 “90d Be gh 30", No. | Observed. Calculated. Difference.|| No. | Observed. |\Calculated. Difference. ft. ft. ft. || | ft. ft. ft. 1 0-11 013 | —002 | 10 | 006 | 0-07 | —0-01 2 | 015 014 | +001 | 11 | 008 | 009 | —0-01 3 | 0-05 006 | —0-01 | 12 | O13 | 0-13 0-00 4 | 028 | 007 | +021 | 13 | 018 | O19 | —001 5 0-18 | O14 | +004 | 14 | 018 | 015 | 40-03 6 | 017 | O16 | 40-01 || 15 | O14 O11 | 40-03 7 | 020 | 021 | -001 | 16 | O13 | O11 | 40-02 $ | 008 | O15 | —007 | 17 | 0-14 014 | 0-00 9 010 | O11 | —0-01 | Mean difference = +0:001 ft. Diurnal Tides of the Coasts of Ireland. 271 Dunmore Tide, Table D. Negative heights at low water for seventeen lunations, commen- cing 1850, September 134175 0™, and ending 1851, Decem- ber 224 22h 30. No. | Observed. \Calculated. Difference.|| No. | Observed. |Calculated.| Difference. ft. ft. ft. | ft. ft. ft. 1 0:23 0:22 +0°01 10 0-15 0-12 +0:03 2 0-18 0-14 +004 || 11 0:09 0-11 —0:02 3 0-23 0°13 +0:10 | 12 0:20 0°12 +0:08 4 0:23 0-12 +011 | 18 0:10 0-18 —0:08 5 013 0-12 +001 || 14 @14 0-22 —0°08 6 | 018 | O19 | —O01 |} 15 | O15 | O16 | —0-01 7 0-18 0:20 —0:02 16 0-15 0-13 +0:02 | 8 0-18 0-20 — 0:02 | 17 0:20 0-13 +0:07 9 | 0-11 013 —0:02 | Mean difference =+0:006 ft. Dunmore Tide, Table E. Difference of observed and calculated times of vanishing at high water, expressed in lunar days. Age of lunar tide =54 19}, No. | Difference.|| No. | Difference.|;) No. | Difference. days. days. days. —2:65 13 —2-40 25 —1:15 —1:56 14 —0:90 26 +1:35 41-60 || 15 | +010 || 27 | —0-90 +030 16 —1:56 28 —0°40 —0°90 17 —0:90 29 —0:90 +1°85 18 —2-30 30 +0:80 +0°60 19 +010 3l 0:00 +1:60 20 — 1:90 32 +260 +110 || 21 | —190 || 33 | —0-20 +1:10 22 +0:50 34 +2:10 +4:10 23 —1:15 35 —0°50 1160 || 24 | +135 =e WK SCEBONDUP wh Mean difference =0-000 days. 272 Dr. Heddle on the Galactite of Haidinger, Duamore Tide, Table F. Difference of observed and calculated times of vanishing at high water, expressed in lunar days. Age of lunar tide =5¢ 144, No. | Difference.|| No. | Difference.|| No. | Difference. days. days. days. 1 | —O-i0 || 13 | 40-20 || 25 | +1-40 2 —1:20 14 —0°60 26 +1:40 3 —0°60 15 +1:70 27 +1:10 4 —0-60 16 +1:90 28 | +1:40 a —2°70 17 —0'60 29 —0-60 6 — 2-00 18 —2:60 30 —3'10 7 —4:60 19 +0°40 31 +0:20 8 —0-°60 20 —0:°60 32 —1:00 9 +1:90 21 —3'10 33 —0-60 10 +1:40 22 —0°60 34 —0°10 11 | 41-40 || 23 | +0-40 || 35 | 43-40 12 | 42:80 || 24 | 44-90 Mean difference =0-000 days. The agreement between the calculated and observed tides shown in the preceding Tables is excellent; and since the tide itself is small, it proves the remarkable care with which the ob- servations were taken at this station. In the next section, which will conclude this abstract, I intend to give some general deductions from the preceding facts, and to compare the results of observation with theory. [To be continued. ] XXXIV. On the Galactite of Haidinger, with Analyses of Scotch Natrolites. By Dr. Heppie*. i seeking out specimens of “ Galactite” for analysis, my first difficulty lay in ascertaining if they were the species to which Haidinger had given this name; and finding that Mr. Rose’s Galactites came from a totally different part of the country from that which afforded my own specimens, I bethought myself of writing to Mr. Greg, the catalogue of whose collection was com- piled by Haidinger himself: the result was that Mr. Greg sent me Galactites from two localities, neither of which I had imagined to be the true one. As Mr. Greg’s localities must be correct, I give them the pre- ference in my analyses. The first was Glenfarg in Fifeshire ; the specimen sent was white, though not very milky; its ana- * Communicated by the Author. with Analyses of Scotch Natrolites. 273 lysis (on 12°5 grs.) afforded,— Silica . 48°24 Alumina . 27:00 Lime *82 Soda 14°82 Water . 9:24. 100-12 As the Glenfarg mineral, however, passes from white to red, by far its most frequent colour, I also submitted a deep red spe- cimen to analysis, to ascertain what the constitutional difference might be; I obtained (on 25 grs.*),— Silica . 47°84 Alumina . 27°112 Lime 4°312 Soda 11°304, Water . . 10:24 100°808 Here a considerable quantity of the soda is replaced by lime ; the colouring matter I could not ascertain. Haidinger’s second locality is the Campsie Hills, the exact spot I do not know; so convinced was I on receiving it that this was a specimen of decomposed Laumontite, that it lay for more than a year unnoticed ; on analysis it afforded,— Silica . 47°3824. Alumina . 27°36 Lime 2°63 Soda 13°354. Water . 10°392 101-060 This is evidently the same substance. The mineral which is generally understood by the Edinburgh mineralogists to be the Galactite of Haidinger, is found at Bishop- town, at the locality whence Greenockite was obtained ; it occurs here of a milky, and also of a delicate pinkish-cream colour. I analysed both :— The white. The pink. Silica: . . 47:60 47°76 Alumina . . 26°60 27°20 Tame ~F 3 44 16 93 Soda .. . 15°86 14°28 Water pick 5. to °9°66 9°56 99°78 99°72 * When not otherwise expressed, my analyses are on 25 grs. 274 Dr. Heddle on the Galactite of Haidinger. A radiated mineral of a still more decided pink tinge, which is found at Glenarbuck and the Long Craig in Dumbartonshire, is also called Galactite. The fibres of all the specimens that I have seen run so much into the Kilpatrick or zeolitic quartz, that I have not been able to free any specimen sufficiently from this matrix to rely upon the correctness of a quantitative ana- lysis ; by a qualitative examination, however, I have ascertained that this is the same substance as the above; lime here also being present in small quantity. These are, I believe, all the localities of Galactite, and all are in composition merely Natrolite (the calculated per-centages of which, for the sake of comparison, are appended in a foot-note*); a small, generally a trifling, proportion of lime in each replaces a portion of the soda, the full amount of which in Natrolite is 16-2 per cent. ; this small portion of lime it is which gives to these Natrolites their whiteness and opacity, and doubtless prevents their assuming the definite crystalline form which the pure mineral under favourable circumstances adopts. Natrolite, though not always recognized as such, occurs in Scotland at several other localities ; at Bowling quarry and at Cochna near old Kilpatrick (as also, I am informed, at Bishop- town), it assumes an appearance very different from its usual aspect. It is here associated with Laumontite, the sheafy variety, and dark green tale, the matrix being highly magnesian in its immediate vicinity. It occurs in spheres imbedded in the rock ; these are white at the centre, but of a fine green at the cireum- ference, apparently from the radiating crystals penetrating the matrix. The specimens from this locality have been sold as Stellite, which (see Phil. Mag. for April 1855) has been shown to be Pectolite, and Dr. R. D. Thomson gave it the latter name to Mr. Greg. Its analysis afforded,— Sila ae ee fe sede AdamInas » = 0a fisn neneue Dr oor Oxide of iron . . *$65 DITIG: 6453 es leet Bn cok gehts Magnesia. . . 403 MOUR- cuss kl ue tee eee Water a. oet 6-2 9728 100°573 A single colourless specimen, which I myself obtained at Bow- * Silica Ces Wl ova Alumina’ 1. We have then by the equation expressing the application of Carnot’s principle [equa- tion (19) of § 116], J OH = Oo 73.5 =m x 40, whence * = RBI) TTS ba ea a he * The value of J now used being 32°2 x 1390=44,758, which is the equivalent of the unit of heat in “absolute units” of work. The “ abso- lute unit of force’’ on which this unit of work is founded, and which is generally used in magnetic and electro-magnetic expressions, is the force 288 Prof. Thomson on the Dynamical Theory of Heat. “Now, by the principle of mechanical effect, we have 280 FJ ({ sdt—©,); if F3®° denote the electromotive force of a copper-iron element of which the two junctions are respectively 0° and 280° C., and Sdt the quantity of heat absorbed per second by a current of unit strength, in passing in copper from a locality at temperature ¢ to a locality at ¢+d¢, and in iron from a locality at ¢+d¢ to a loca- lity at ¢*; since the Peltier generation of heat between copper and iron at their neutral point, 280°, vanishes}, and therefore the only absorption of heat is that due to the electric convection expressed by frat ; while there is evolution of heat amounting to @, at the cold junction, and of mechanical effect by the current amounting to F units of work. If we estimate the value of i aa as half what it would be were the electromotive force the same for all‘equal differences of temperature as for small differences near the freezing-point t, that is, if we take Fy” = x 40m x 280, the preceding equation becomes 280 140 x m x 10=3( | sdt—®,). 0 But we found m x 40 = "Ov. Hence 280 140u 140 3 sdt=O (1+—# =0 (1+ 55 )=0 x = and Wet-bulb Thermometers.” In a Letter of Lieut. Noble, R.N., of Toronto, to Charles R. Weld, Esq. Toronto, September 10th, 1855. My pear S1r,—The results of the accompanying table for com- puting the dew-point from readings of the dry- and wet-bulb thermo- meters, are, as I believe you know, derived from observations taken here during last winter by Mr. Campbell and myself :— Tase for computing the Dew-point from Readings of the Dry- and Wet-Bulb Thermometers. Proba- eel Probable |Measure of Number : f th ge : ble errorjof preci- €Tror of the) precision | It is therefore an Toes | Factor of Pe ofa |sion of a adopted of the | equal chance that (t) | (f)- ‘Gone single | single factor adopted |the true factor lies 7 | | (m) datum | datum | p _ Y_.| factor __ between | 9 (r). (Rh). | A/m |H=h A/mm. 48 to 5)| 231| 21 *30 | 1590 07 7-287 | 2:24and 2-38 . 47 | 2:38] 13 26 | 1822) :07 6569 | 2-31... 2°45 42... 45 | 253) 41 40 | 1-189 06 7613 | 2°47... 2:59 40... 41] 2°63) 17 ‘41 | 1-163 10 4-796 | 2:53 ... 2°73 38... 39} 2°83] 25 48 | 0-999 09 4-994 | 2°74 ... 2:92 34... 37 | 302) 64 43 | V1k4| +05 8-912 | 2°97 ... 3:07 32... 338 | 3°33) 25 “63 | “767 12 3:835 | 321... 3°45 30... 31 | 3°81) 22 4.3) Al ey oc fe | 3633 | 3°65 ... 3:97 28 ... 29 | 4:40) 27 “66 | °723 13 3756 | 427... 453 24... 27) 5-46) 43 82 | °577 13 3°787 | 5°33... 5°59 22... 23| 606, 15 1:20 | ‘397 “31 1535 | 5°75... 637 20... 21) 6:93 6 1:40 | -341) HVE "834 | 636... 7:50 1 ke eS 2 Bil 15 aa | 1-44 | 331 “31 1517 | 682... 7:44 16... 17 | 7:60) 20 1:76 | :271 39 1:209 | 7:21 ... 7:99 14 i283 15 hig 8:97)\ (17 1:72 | ‘277 42 1141 | 855 ... 9:39 12... 13 | 10:30] 20 2:53 | +188 “56 “642 | 9-74 ... 10:86 10 eo ON 50) | a 2-19 | -218 66 723 | 10°84 ... 12°16 8... 9 | 13:06 8 4:63 | :103| 1:64 -292 |11-42 ... 14:70 6... 7 | 15°30 7 3-65 | +130) 1:38 345 | 13°92 ... 16°68 0... 5 | 16:23) 14 1-87 | °255 50 955 |15°73 ... 16°73 —1 ... —4} 19:37| 10 4-11.) (:116) . 1:30 *367 | 18-07 ... 20°67 —5 ...—10 | 21°64 6 465 | -102 1:90 ‘251 | 19°74 ... 23°54 —11 ...—16 | 37°83 6 |10-96 | -044 4-48 107 | 33°35 ... 42°31 These results will be obvious at a glance; but a few remarks upon the instruments employed, and upon the degree of reliance to be placed upon them, may not be uninteresting. The dry- and wet-bulb thermometers (for which we were indebted to the kindness of Prof. Cherriman, Director of the Magnetic Ob- servatory, Toronto) were made by Negretti and Zambra, and their index errors were ascertained, above 3z° by Mr. Glaisher, and below 32° by ourselves, by comparison with a Kew standard. The divi- sions upon these thermometers were too small to read 0°1 with great accuracy ; and in discussing our observations at low tempera- tures, we were in consequence obliged to reject such as would, with Lieut. Noble on the Determination of the Dew-point. 305 an error of 0°1 in the reading, introduce a considerable error into the factor. You will observe that the table does not extend below —16°, although we have repeatedly every winter the mercury below —20°, and occasionally below —30°. The only thermometer, however, which we could trust as a wet-bulb in investigations so delicate was not graduated below —16°. For obtaining the dew-point by direct observation, we used the condensing hygrometer invented by M. Regnault. We obtained dew with this beautiful instrument at all tempera- tures (limited only by the graduation of the thermometer —35°), the only requisites when the thermometer is very low being time and pure ether*. I can testify from experience that this hygro- meter obviates all the disadvantages of Daniell’s, which M. Regnault enumerates in his hygrometrical researches. In order to show the reliance that may be placed upon our results, we have put opposite each factor in the table the probable error and measure of precision of the single data (from which the factor (f) was derived), and also the probable error, measure of precision, and limits of certainty of the adopted factor. The nomenclature and notation are thus employed by Encke in his Memoir on the Method of Least Squares. The measure of precision (4), as was indeed to have been ex- pected, decreases with the temperature. This fact is not however of so much importance as might at first appear. For the dew-point is given by the equation,— T=t—f(t—?), where (T) is the temperature of the dew-point, (¢) that of the air, (t—t') the difference between the dry- and wet-bulb thermometers, and (f) the factor whose value is given in the table. Now taking the temperatures 42° and 22°, it appears from the table that the probable error of (/) for a single observation is at the latter temperature three times greater than at the former. But (t—t’) is on an average about three times as great at 42° as at 22°. Hence the probable error of the dew-point at both temperatures is very nearly the same. We have extended our table to 51° for the purpose of comparison with the ‘‘ Greenwich factors.” I must however remark, that it is probable that the factors, which we have given above 40°, are rather greater than they would have been had the observations discussed extended through a longer space of time, the majority at these tem- peratures having been taken last spring, when the air was very remarkably dry; and experience shows that when (¢—?') is un- usually great, the deduced factor, instead of being more accurate, is generally much too large. As an instance, I may cite an observation taken on April 29th, when the temperature of the air was 43°°6, that of evaporation was * The ether we employed below —20° was the first that passed over, resulting from the distillation of washed ether with quicklime. 306 Royal Society. 31°°6, and that of the dew-point 3°°2. The fraction of saturation : 19 , ; on this occasion was 00’ and the factor derived from this observa- tion was 3°36; this being much the largest deviation from the adopted mean 2°53. The cause of this discrepancy is doubtless owing to the heat that the wet-bulb thermometer derives from the radiation of surrounding objects ; and were observations sufficiently numerous, it might con- duce to accuracy were the factors calculated for every degree of difference in the value of (¢—t'). We purpose instituting a comparison between two wet-bulb ther- mometers placed in similar boxes, the one box coated with lamp- black, the other with a polished metallic surface. Below 32° our results do not appear to coincide with the factors deduced from the Greenwich observations ; and the causes of these discrepancies I must leave to time. As, however, we have had considerable experience at these tempe- ratures, I may perhaps be doing service to observers in bringing before their notice two causes of error, to which we have found our- selves particularly liable when the thermometer is near 32°. Ist. If the air is a little above, and has been below 32°, there will frequently be a small button of ice at the foot of the wet-bulb ther- mometer, which is not easily perceived, and which will keep it at 32° when the temperature of evaporation is really above that point. 2ndly. It is well known that under certain circumstances water may be cooled below 32° without freezing; and an example will perhaps best show the error which this fact may occasion. Let us suppose that the temperature of the air is 27°, and that when the thermometer is wetted it sinks to 26°, and then rises. Should it rise very slowly, or not at all, the probability is that 26° is the true temperature of evaporation, but if rapidly, the rise may be due to the conversion of the water into ice; and it will be prudent to observe whether or not the thermometer again commences to sink. We have frequently observed this phenomenon, and I am quite at a loss to what to ascribe its uncertainty. It has occurred both in a high wind and a calm (the thermometers are protected from the full force of the wind), and it also appeared to be quite uncertain at what temperature the water might freeze. I am obliged to admit that the limits of certainty of the factors below zero are not quite so close as could be desired. This is partly attributable to our being obliged to reject many observations made with a thermometer which was broken before its index-errors were fully ascertained; but Mr. Campbell and I must claim the indul- gence of those who know the difficulty of taking observations requiring so much time and accuracy at such temperatures, and fre- quently at six o’clock in the morning. Believe me, &c., W. Nose, Lt. RN. C. R. Weld, Hsq., Assist. Sec. Royal Soc. Cambridge Philosophical Society. 307 CAMBRIDGE PHILOSOPHICAL SOUIETY. [Continued from p. 242.] Noy. 13, ]854.—A paper, by R. L. Ellis, Esq., was read, entitled “Remarks on the Fundamental Principle of the Theory of Proba- bilities.” Also, ‘‘On the Purbeck Strata of Dorsetshire.” By the Rev. O. Fisher. The object of this paper was to describe the beds from which a series of insect remains and other fossils had been collected by the author, and presented to the Woodwardian Museum. The connexion of the Purbeck beds with the Oolitic rather than with the Wealden series was maintained, while both were shown to be unconformable in this district to the cretaceous system. Reasons were given for thinking that the materials, of which both the Wealden and Purbeck were composed, had travelled from west to east; and the beds of the New Red Sandstone, as they occur in Devonshire, were pointed out as affording a mass of strata which would furnish a detritus of the character of a large portion of the Baghngs sands of Hampshire and Dorsetshire. In describing the Purbeck beds,the author fillawedeee system of the late Professor E. Forbes, dividing them into upper, middle, and lower; and entered into some detail of the alternations of salt and freshwater conditions that prevailed during their deposition. The aspects under which the same beds appear at different points of the district under examination were particularized, and it was attempted to be shown that these were in conformity with the theory of a current setting from the west towards the east. The mode of occurrence of the remains of insects in the middle and lower Purbecks was somewhat minutely described, and it was suggested that some interesting chronological speculations might be grounded upon it. The paper concluded with an attempt to explain the singular frac- tured condition of about thirty feet of the lower Purbeck strata throughout the eastern part of the county. It was supposed that this might have been caused by the deposition of sediment upon the remains of the Portland forest before the mass of the trees had been removed by decomposition; the sediment, after it had become con- solidated, settling unequally as the carbonaceous matter was gra- dually removed. Nov. 27.—Prof. Willis gave an account of a new form of Atwood’s Machine. Dec. 11.—A communication was made by Dr. Paget on a case of involuntary tendency to fall forwards. Feb. 19, 1855.—Mr. Hopkins gave a lecture on certain changes of Terrestrial Temperature, and the causes to which they may be attributed. March 5.—Dr. Clark gave an account of some recent discoveries respecting the origin, migrations, and metamorphoses of Entozoa, and their bearing on the notion of spontaneous generation. 308 Cambridge Philosophical Society :— April 23.—A paper was read by the Master of Trinity, on Plato’s Survey of the Sciences, contained in the seventh book of the Republic. Plato, like Francis Bacon, took a review of the sciences of his time ; and like him, complained how little attention was given to the phi- losophy which they involved. The sciences which Plato enumerates are arithmetic and plane geometry, treated as collections of abstract and permanent truths; solid geometry, which he ‘‘notes as deficient” in his time, although, in fact, he and his school were in possession of the doctrine of the “ five regular solids ;”’ astronomy, in which he demands a science which should be elevated above the mere know- ledge of phenomena. The visible appearances of the heavens only suggest the problems with which true astronomy deals; as beautiful geometrical diagrams do not prove, but only suggest geometrical propositions. Finally, Plato notices the subject of harmonics, in which he requires a science which shall deal with truths more exact than the ear can establish, as in astronomy he requires truths more exact than the eye can assure us of. It was remarked also, that such requirements had led to the progress of science in general, and to such inquiries and discoveries as those of Kepler in particular. May 21.—A paper was read ‘“‘ On the singular Points of Curves.” By Professor De Morgan. Mr. De Morgan defines a curve as the collection of all points whose co-ordinates satisfy a given equation; and contends for this definition as necessary in geometrical algebra, whatever limitation may be imposed in algebraic geometry. He divides singular points into points of singular position and points of singular curvature; the character of the former depending on the axes, but not that of the latter. Both species are defined as possessing a notable property, and such as no arc of the curve, however small, can have at all its oints. i The form first considered is that of which the case usually taken is an algebraic curve. Let ¢(2, y) be a function which for all real and finite values of x and y is real, finite, and univocal; let the curve be ¢(2, y) =0, considered as an individual of the family ¢(x, y) =const. The two curves d¢ : dr=0, dp: dy=0, or ¢,=0, ¢y=0, are the sub- ordinates of this system, on which the singular points of all depend. When ¢ is not reducible to another function of the same kind by extraction of a root, it divides the plane of co-ordinates into regions in which, severally, it is always positive or always negative. By this consideration it is easily shown (independently of y', y”, &c.), that if (x+dz, y+dy) be a point on the tangent at (2, y), ¢(@+dz, y+ dy) has the sign of $2,dx*+ 2p.,dady + oy,dy?. Hence, immediately after leaving the curve, ¢ agrees with or differs from —@,y” at the point left, according as the curve is left on the convex or the concave side. Hence easily follow the criteria of flexure, and also the following relation between any two points whatsoever of the curve. Let two points be called similar when a line drawn from one to the other cuts the curve an even number of times (0 included) with the same abutments (on convexity or on concavity), or an odd number of times with different abutments. Let other points be Prof. De Morgan on the singular Points of Curves. 309° called dissimilar. These points are similar or dissimilar, according as their values of g, .y” agree or differ in sign. An 4 priori proof is given that multiple points, cusps, and isolated points, must be determined by 9,=0, ¢y=0, or can only take place when both subordinates meet the curve. It is shown that, in the system (x, y)= const., the cusp of ¢(7, y)=0 must be an evanes- cent loop, and the isolated point an evanescent oval, or bounded portion. Some discussion of the meaning of y!=a+b /—1 at an isolated point is given. There have been two methods of treating the singular points. The first has recourse to the theory of equations, using differentia- tion, if at all, only to supply coefficients. The second attempts canonical forms derived from differential coefficients, and examines, in succession, the meaning and bearing of the successive orders of differential coefficients. Mr. De Morgan affirms that this second method cannot be what it pretends to be; and, by treating it gene- rally, shows that its questions are ultimately dependent upon the theory of equations. An equation of the form SAy'*=0, when it has no equal roots, decides the character of a singular point defini- tively ; and reduces it to a number of intersecting branches without contact, a number of coinciding isolated points without real tangents, or some of one and some of the other. When the equation has some real roots, each set furnishes either multiple branches with contact, or cusps, or conjugate points with real tangents. All this is easily illustrated by examining the curve in which ¢(z, y) is an infinitely small constant, near to the singular point of g(a, y)=0. A theorem given by Lagrange, and strongly indicated in the writings of Newton, Taylor, Stirling, Cramer, and John Stewart, but apparently nearly forgotten, solves the question of finding the higher or lower degrees of all the roots of ZAy*=0, where A is a function of w of the degree a; that is, where A=2%(a+A’), and A! vanishes when = o or when z=0. By this theorem (which is also given in the first* Number of the Quarterly Journal of Mathe- matics), y being #*(u+U), all the values of r, and their corresponding values of u, are very easily found; and repetition of the process upon a transformed equation gives U=2"(u,+U,), and so on. It obviously follows, that when the origin is removed to any singular point of a curve, the discussion of the branches which pass through that point, and of their contacts with the tangent and each other, is made very easy. In proof of this, the author takes the following instance,— w+ alt + glly—gxsy? + 2QeTy3 —aty* + y6 —3ay? +alty!s =0, and discusses its infinite branches, and the sextuple point at the origin (which turns out to be a couple of isolated points, and a cusp of similar flexures), with very much less space and trouble than ordi- nary methods would demand from a much less complicated instance. It is also shown that the lower form of Lagrange’s theorem solves the following question :—Given an equation with a certain number of * There attributed to Mr. Minding, by a mistake caused by M. Serret, who incorporates it with a theorem of Mr. Minding, without any notice of its author. 310 Cambridge Philosophical Society. equal roots, what effect will be produced upon these roots by given infinitesimal alterations in the coefficients, how many will remain real, and how many will become imaginary ? Newton has given the foundation and the chief step of a geome- trical method (Newton’s parallelogram) which has passed into oblivion, though it occurs in the celebrated second letter to Oldenburg, has been fully described by Stirling, used by Taylor and De Gua, and forms the main method of Cramer’s work on curves. Mr. De Mor- gan proposes to call it the method of co-ordinated exponents. He proceeds to describe and enlarge this method; observing that, of the polygon which represents an equation, Newton and his fol- lowers are in full possession of the connexion of the sides with the solutions, and fail only in not grasping the connexion of the whole polygon with the whole equation. Both Newton’s method and Lagrange’s, the second of which is an arithmetical version of the first, may be applied to irrational equations, but it will be convenient to confine the description to the form Zav”y”"=0, where m and x are integers. In ax™y”, let n be an abscissa, and m an ordinate, and let (m, n) be called the exponent point of the term aw”y”. Take some paper ruled in squares (or ruled both ways in any manner, for any equal rectangles will do) to facilitate the process when z and m are always integers, and lay down all the exponent points in Laxv™y"=0. Through some of these points draw a convex polygon including all the rest, which can only be done in one way. Should the points be so many and so scattered that some method must be applied, the geometrical method is a translation of the main arithmetical method of Lagrange’s theorem. The points which end on, or otherwise fall in, the sides of the polygon show the essential terms of the equa- tion: no others are wanted to determine g and wu in y=a"(u+U). The upper contour of the polygon shows how all the solutions com- mence in descending powers of x; the under contour does the same for ascending powers. Take any side of either contour, its projec- tion on the axis of z shows the number of roots it represents, the tangent of the angle it makes with the negative side of the axis of n shows the value of r. It will not be needful to abstract the developments given in the paper: we shall only notice the inverse method. The following example is taken, and the construction of the equation is even easier (under Cramer’s form) than the direct treatment of it. The example chosen by the author is the following :—Required 6(2, y)=0, of the twelfth dimension in terms of y, such that the twelve roots of y, with reference to lower degrees, shall be as follows: two roots = the degree 1, four of $, two of 0, one of —1, two of —3, one of — But with reference to ‘higher degrees, there are to be one root of ie degree 3, two of > , three of 0, three of —1i, two of —1, one of — On examination Peace conditions are eee) compatible, and the a general equation which satisties the conditions is found. The paper is terminated by a discussion on the pointed branch, for the admission of which, as a branch altogether composed of sin- gular points, the author contends. Geological Society. 311 GEOLOGICAL SOCIETY. [Continued from p. 240.] February 20, 1856.—D. Sharpe, Esq., President, in the Chair. _ The following communications were read : 1. ‘‘ Notice of a Visit to the Dead Sea.” By H. Poole, Esq. Forwarded from the Foreign Office by order of Lord Clarendon. Mr. Poole went to this district to look for nitre, which was re- ported to occur there; but he met with none, and found reason to suppose that the report was unfounded. He noticed bituminous shales at Nebi Mousa, and sulphurous earths both there and at El Lisan on the Dead Sea, but the sulphur was not found in any large quantity. The author exhibited to the meeting a series of these deposits, and of rock-salt and other minerals from the neighbourhood of the Dead Sea, together with recent natural history specimens, volcanic and other rock-specimens, and some tertiary and cretaceous fossils from the district visited. 2. “On the Affinities of the great extinct Bird (Gastornis parisi- ensis, Hébert) from the lower Eocene near Paris.” By Prof. Owen, F.R.S., F.G.S. Prof. Owen communicated the results of his comparisons of the fossil tibia of the Gastornis parisiensis, Hébert,—a large bird from the lower Eocene deposits at Meudon near Paris—with the tibiz of known recent and fossil birds. The tibia of the Gastornis presents the same median position of the supra-tendinal bridge as in the Albatross and the lamellirostral web-footed birds ; but, as the same position of the bridge occurs in the Notornis, the Gallinule, the Raven, and some accipitrine birds, that character is not conclusive of the affinities of the Gastornis to the Palmipeds; and it is further invalidated by a difference in the aspect of the plane of the lower outlet of the bridge. In the Alba- tross (Diomedea) and the Lamellirostres, the foramen or outlet looks directly forwards; its plane is vertical. In the oblique aspect of that outlet, the Gastornis more resembles the large Waders (Gralle) and the Dinornis tribe. Amongst the Gallinacee, the Turkey (Me- leagris) nearly resembles the Gastornis in the position of the bridge ; and more nearly resembles it than does the Albatross or the Swan in the low tuberosity external to the bridge above the base of the outer condyle, as well as in the shallow groove dividing that tuberosity from the bridge. The depression on the fore-part of the tibia above the distal condyles, if natural to the Gastornis, is a structure not precisely repeated in any of the Gralle. In the Ciconia Argala the anterior interspace of the condyles forms a cavity, bounded above by the tubercle and ridge developed from the bridge, and by the oblique converging upper borders of the condyles below. The canal of the bridge opens below into the concavity. In the Grus Antigone the lower border of the outlet of the bridge defines, with a tubercle ex- ternal to it, the shallow supracondyloid cavity; but there is no definite fossa, like that in the Gastornis. In the Notornis, the breadth of the lower end of the tibia a little 312 Geological Society :— exceeds the depth or fore-and-aft diameter of the condyles. The supra-tendinal bridge is of moderate breadth, is transverse, and median in position; its lower outlet looks forward just above the wide and shallow intercondyloid space. The extinct Aptornis chiefly differs from the Notornis in the less median position of the bridge, and in the more shallow canal leading to it. In the Dinornis, the breadth and depth of the condyles are equal; the outer condyle is the broad- est, the inner one is the most prominent; their articular surfaces are so continuous as to leave no space answering to the intercondy- loid space in the Aptornis, Notornis, &c. The bridge is situated nearer the inner side of the bone, is subtransverse, rather narrow, with a widely elliptical lower outlet opening above the inner condyle. The Gastornis was a bird of the size of the Ostrich, but with more bulky proportions, and in that respect more resembling the Dinornis : it appears to have had nearer affinities with the wading order, and therein, perhaps, to the Raillide; but the modifications of its tibia indicate a genus of birds distinct from all previously known genera. 8. ‘Description of some Mammalian Fossils from the Red Crag of Suffolk.” By Prof. Owen, F.R.S., F.G.S. The fossils described in this paper were referred by the author to the following genera and species :—Rhinoceros, a species nearly allied to, if not identical with, Rh. Schleiermacheri, Kaup; from crag-pits at Wolverston, Sutton, and Felixstow, Suffolk. Tapirus priscus, Kaup ; from Sutton. Sus paleocherus, Kaup; from Sutton. Sus antiquus, Kaup; from Ramsholt, Suffolk. Equus: two species, one appa- rently Eq. plicidens, Owen; from Bawdsey, Suffolk. Cervus dicra- nocerus, Kaup; from Ipswich and Sutton. Cervus megaceros, from Felixstow. Ursus, sp. indet., less than Ur. speleus. Canis, appa- rently C. Lupus. Felix pardoides, Owen; from Newbourn, Suffolk. Mastodon longirostris, Kaup; from Sutton, Felixstow, and Ipswich. | Ziphius longirostris, Cuv. (Dioplodon Becanii, Gervais) ; Hoploceius crassidens, Gervais; Balenodon affnis, Bal. definita, Bal. gibbosa, Bal. emarginata, Owen; and remains of species of Delphinus, of the size of the Grampus. The conclusion which the author deduced from the large propor- tion of miocene forms of mammalia, and the very great numerical superiority of individual fossil specimens from the Red Crag refer- able to miocene species, and from the admixture of these fossils with a few eocene and pleistocene species, was that the Red Crag was the débris of former tertiary strata of different periods, and, in a great proportion, of the miocene period. March 5, 1856.—D. Sharpe, Esq., President, in the Chair, The following communications were read :— 1. ‘Notes on the Geology of some parts of South Africa.” By R. N. Rubidge, Esq. In a letter to Sir Roderick Murchison, F.G.S. Mr. Rubidge first referred to the occurrence of gold at Smithfield in the Orange River Sovereignty, as detailed in his letter of May 1854, published in the Society’s Journal, No. 41; and stated that several pieces of gold had since been found at the spot described in Mr. Rubidge on the Geology of some parts of South Africa. 313 the letter referred to. Besides being found in the alluvium there, gold was met with in a quartz-vein in the trap traversing the strati- fied rock,—in other quartz associated with the trap,—and in a mass of limestone enclosed in the trap-dyke ;—but none in the stratified rock itself (which belongs to the Dicynodon or Karoo Series). Mr. Rubidge next alluded to the fossil plants which he there found in the strata; some of these he referred with doubt to Calamites. Six years ago also the author found numerous vegetable remains (some of which were possibly referable to Lepidodendron) at Jackall’s Kop, on the eastern side of the Stormberg Range, in the same formation as that of the Drakensberg and Smithfield; and Calamite-like plants in the western part of the Zuurbergen. The author remarked that the plant-remains above referred to much resembled those collected by Mr. Bain at the Ecca Heights in rocks of the Karoo Series. Mr. Rubidge had also found bones of the Dicynodon near the Caledon River and at Halse’s farm six miles from Smithfield. From various observations by himself and others, the author had been enabled to recognize the existence of the Dicynodon or Karoo rocks in the Drakensberg, at Harriesmith, at Winburg, and even at Megaliesberg: and Dr. Sutherland has lately described the same rocks in Natal, where they are rich in coal. The amygdaloid rock which supplies theagate-gravel of the Orange, Caledon, Kroai, and Vaal Rivers appears to exist in the ‘“‘ Mont des Sources” in the Drakensberg, as an unworn specimen was found in the Eland River (a tributary of the Vaal), not more than twelve miles from its source. Lastly, Mr. Rubidge supplied some remarks on the geology of the copper district of Namaqualand and bordering countries. Granitic rocks of several varieties occur, together with gneiss, mica-schist, and talc-schist. The gneiss strikes 5° to 20° S. of W., and dips alternately N. and 8.; one dip continuing for many miles. On the hills the gneiss and schists are covered by horizontal sandstones, which appear to be the same as the sandstone of Table Mountain, and continuous with it. The copper is found in fissures of the gneiss, where it is locally disturbed in its dip, the strike remaining unaltered; that is, along anticlinal and synclinal folds or axes; also in fissures extending nearly in the direction of the magnetic meridian, and in crevices between masses of rock, with no veinstone or gangue: the oxides and silicates often appear to be infiltered into the rock-mass. The ores most common are red and black oxides, green and blue silicates, purple and yellow sulphurets, and afew carbonates. Granitic rocks are often found in the axes above referred to. 2. “On the Lowest Sedimentary Rocks of the South of Scotland.” By Prof. Harkness, F.G.S. The author first described in detail the indications of the axis of the Silurian rocks of Dumfriesshire. It is well seen on the Esk River and the Rennel Burn running into the Esk,—on the Dryfe water a little above Borland Bridge,—in the Shaw Burn, and in the upper part of Auchenrodden Burn in Applegarth parish. Here it is inter. Phil. Mag. 8. 4. Vol. 11. No. 72. April 1856. ¥ 314 Geological Society. rupted by the Corncockle Sandstone, but reappears, or its proximity is traceable,in Lochmaben and Torthorwald parishes, striking towards the Criffel in Kirkcudbrightshire. This E.N.E. and W.S.W. direction agrees with that of the axis observed by Mr. Nichol in Roxburgh- shire. The axis itself, where seen (in the Rennel Burn, in Dryfe water, and in Torthorwald), consists of an anticlinal of purple grits. The overlying rocks are thin-bedded and alternating sandstones and purplish shales; and these appear to have been much folded, re- peated again and again by flexures, and considerably altered by the consequent pressure. The author then adduces evidence of these sandstones and shales having been deposited in shallow water, and probably under littoral conditions, The sandstones to the south of the axis, at Binks in Rox- burghshire, are ripple-marked, and the alternations of sandstone and shale arefrequent. There have beenhere observed casts of desiccation- cracks,—surface-pits, resulting, in the author’s opinion, from littoral action,—Annelid tracks,—the track of a small animal, probably Crustacean, resembling in miniature the Protichnites of the Potsdam sandstone,—and Fucoids. In the low-lying purplish shale (overlying the axis to the south) which occurs with thin-bedded sandstone at the Upper Cleugh Burn, in Applegarth parish, Protovirgularia is met with, which is found also in the Barlae flags; and Graptolites occur at Dalton Rocks, in the parish of Dalton (also on the south side of the axis), in shale associated with ripple-marked sandstone, and distinct from the other Graptolitie rocks of Dumfriesshire, On the south side of the axis there is no trace of the great An- thracitic and Graptolitic bands which traverse the north-eastern part of Dumfriesshire ; and the author thinks that no strata occupying so high a position are developed on the south side of the axis in the district under notice. He thinks also that the fossiliferous beds of Grieston (Peeblesshire) and what he regards as their equivalents in Kirkcudbrightshire (the Barlae flags) should have a lower position than that of the anthracitic and graptolitic shales assigned to them ; although, from the numerous flexures that the rocks have here undergone, their relative positions is much obscured; and he thinks that they may be the Scottish representatives of the fucoidal sand- stones underlying the Graptolite-beds of Sweden and Norway. Mr. Harkness regards the fossiliferous shales and sandstones, more particularly referred to in this communication, as underlying the Barlae and Grieston flags, and as the lowest rocks in Scotland that have yet afforded fossils; and therefore as containing some of the earliest records we possess of organized existence. 3. “ On Fossil Remains in the Cambrian Rocks of the Longmynd.”’ By J. W. Salter, Esq., F.G.S. In this paper the author communicated the discovery of organic remains in some of those ancient sediments which have hitherto been termed ‘‘ Azoic.”’ Of these fossils, some (traces of Annelides and fragments of a Trilobite) were found by Mr. Salter in the unaltered sandstone beds on the eastern side of the Longmynd; and another (a Fucoid?) he discovered in the Moel-y-ci near Bangor. Royal Institution. 315 The rocks of the Longmynd that have yielded the fossils referred to are nearly vertrical beds of hard flaggy sandstone, coinciding in strike with that of the Longmynd, and about 14 mile east of the principal ridge. These beds form part of a series of bluish-grey sandstones, alternating with purplish slaty beds, all of which lie below the con- glomerates and red sandstones of the Portway, and above the thick series of dark-olive schists, seen at Church Stretton, &c., which are the lowest portion of the Longmynd series. Of the Annelid traces, some (which the author has referred to Arenicola didyma) were found at Stretton, Callow Hill, and other spots in the upper portion of the sandstone above mentioned, where it is flaggy, rippled, and micaceous. Annelid tubes or tracks were also found at Callow Hill in the same rock. The most interesting of the fossils from this sandstone, however, are the indications of fragments, cephalic (?) and caudal, of a trilobite allied apparently to the Deikelocephalus of Dr. Owen. To the Longmynd Trilobite Mr. Salter has given the name of Paleopyge Ramsayi. It occurred at Little Stretton, &c. The author also described in detail some of the surface-markings of the flags, which he referred to ripples and littoral . action. ROYAL INSTITUTION OF GREAT BRITAIN. January 25, 1856.—‘‘Inferences from the Negation of Per- petual Motion.” By W. R. Grove, Esq., Q.C., F.R.S., M.R.I. Scattered among the writings of philosophers will be found allu- sions to the subject of perpetual motion, and here and there are arguments like the following; such a phenomenon cannot take place, or such a theory must be fallacious, because it involves the idea of perpetual motion: thus Dr. Roget advanced as an argument against the contact theory of electricity, as originally propounded, that if mere contact of dissimilar metals, without any chemical or molecular change, could produce electricity, then as electricity could in its turn be made to produce motion, we should thus get per- petual motion. It may be well to define, as far as such a definition is possible, what is commonly meant by the term perpetual motion. In one sense, all motion, or rather all force, is perpetual; for example, if a clock weight be wound up, it represents the force derived from the muscles of the arm which turns the key; the muscles again derive force indirectly from the chemical action of the food, and so on. As the weight descends, it conveys motion to the wheels and pen- dulum ; the former giving force off in the form of heat from friction, the latter communicating motion to the air in contact with it, thence to the case of the clock, thence to the air of the room,—proved in a very simple manner by the ticking heard, which is, in fact, a blow to the organ of hearing. Although ultimately lost to our senses, there is no reason to suppose that the force is ever in fact lost. The weight thus acting, reaches the ground quietly, and produces no effect at the termination of its course. Y2 316 Royal Institution. If, instead of being allowed to communicate its force to the works of the clock, the weight be allowed to descend suddenly, as by cutting the string by which it is suspended, it strikes the floor with a force which shakes the house ; and thus conveys, almost instantaneously, the amount of foree which would be gradually dissipated, though not ultimately consumed, by the clock in a week or nine days. This idea, however, of the perpetuity of force, is not what is com- monly understood by the term perpetual motion : that expression is used to convey the notion of a motive machine, the initial force of which is restored by the motion produced by itself,—a clock, so to speak, which winds itself up by its own wheels and pendulum, a pump which keeps itself going by the weight of the water which it has raised. Another notion, arising from a confusion between static and dynamic forces, was, that motion might be obtained without transferring force, as by a permanent magnet. All sound philoso- phers are of opinion that such effects are impossible ; the work done by a given force, even assuming there were no such thing as friction, aérial resistance, &c., could never be more than equal to the initial force ; the theoretical limit is equilibrium. The weight raised at one end of a lever can never, without the fresh application of extra- neous force, raise the opposite weight which has produced its own elevation. A force can only produce motion when the resistance to it is less powerful than itself; if equal, it is equilibrium: thus if motion be produced, the resistance, being less than the initial or pro- ducing force, cannot reproduce this ; for then the weaker would con- quer the stronger force. The object of this evening’s communication was not, however, to adduce proofs that perpetual motion, in the sense above defined, is impossible; but assuming that as a recognized truth, to show certain consequences which had resulted, and others which were likely to result, from the negation of perpetual motion; and how this negation may be made a substantive and valuable aid to scientific investiga- tion. After Cirsted made his discovery of electro-magnetism, philoso- phers of the highest attainments argued, that as a current of elec- tricity, circulating in a wire round a bar of iron, produced magnetism, and as action and reaction are equal, and in contrary directions, a magnet placed within a spiral of wire should produce in the wire an electrical current: had it occurred to their minds that, if a per- manent magnet could so produce electricity, and thence necessarily motion, they would thus get, in effect, perpetual motion, they would probably have anticipated the discovery of Faraday, and found that all that was required was to move the magnet with reference to the wire, and thus electricity might have been expected to be produced by a magnet without involving the supposed absurdity. In a very different instance, viz. the expansion of water when freezing, not only heat, or the expansive force given to other bodies by a body cooling, would be given out by water freezing, but also the force due to the converse expansion in the body itself; and upon the argument that force would, in this case, be got out of nothing, Royal Institution. 317 Mr. J. Thomson saw that this supposed impossibility would not result if the freezing-point of water were lowered by pressure, which was experimentally proved to be the case by his brother. In the effects of dilatation and contraction by heat and cold, when applied to produce mechanical effects, and consequently in the theory of the steam-engine, this subject possesses a greater practical interest. Watt supposed, that a given weight of water required the same quantity of what is termed total heat (that is, the sensible added to the latent heat) to keep it in the state of vapour, whatever was the pressure to which it was subjected, and consequently, however its ex- pansive force varied. Clement Desormes was also supposed to have experimentally verified this law, If this were so, vapour raising a pis- ton with a weight attached would produce mechanical power; and yet the same heat existing as at first, there would be no expenditure of the initial force; and if we suppose that the heat in the condenser was the real representative of the original heat, we should get per- petual motion. Southern supposed that the latent heat was con- stant, and that the heat of vapour under pressure increased as the sensible heat. M. Despretz, in 1832, made some experiments which led him to the conclusion that the increase was not in the same ratio as the sensible heat, but that yet there was an increase; a result confirmed and verified with great accuracy by M. Regnault, in some recent and elaborate researches. What seems to have occasioned the error in Watt and Clement Desormes’ experiments was, the idea involved in the term latent heat; by which, supposing the phe- nomenon of the disappearance of sensible heat to be due to the ab- sorption of a material substance, that substance, ‘caloric,’ was thought to be restored when the vapour was condensed by water, even though the water was not subjected to pressure; but to estimate the total heat of vapour under pressure, the vapour should be condensed while subjected to the same pressure as that under which it is generated, as was done in M. Despretz and M. Regnault’s experiments. Carnot’s theory, that the mechanical force is produced by the transfer of heat, and that there is no ultimate cost or expenditure of heat in producing it, was founded in part on similar considerations; it is true that mechanical motion may be produced by the transfer of heat from a higher to a lower temperature, without ultimate loss, or, strictly speaking, with an infinitely small loss, but not, as he seemed to think, an available mechanical force, except upon an assumption which he did not make, and to which allusion will pre- sently be made. Thus, let a weight be supposed to rest on a piston confining air of a certain temperature, say 50°, in a vessel non-con- ducting for heat; part of this temperature will be due to the press- ure exerted, since compression produces heat in air, while dilatation produces cold. If the air be now heated, say to 70°, the piston, with the weight attached, will rise, and the temperature in consequence of the expansion of the air will cool somewhat, say to 69° (the heat of friction of the piston may be taken to compensate the power lost by friction) : if nowa cold body be made to abstract 20°, the piston descending will, by its pressure, restore. the 1° lost by expansion ; 318 Royal Institution. and when the piston has returned to its first position, the original 50° will remain as at first. Suppose this experiment repeated up to the rise of the piston, but when the piston is at its full elevation, and the cold body is applied, let the weight be removed, so as to drop upon a wheel, or to be used for other mechanical purposes, the de- scending piston will not now reach its original point without more heat being abstracted; from the removal of the weight there will not be the same force to restore the 1°, and the temperature will be 49°, or some fraction short of the original 50°; if this were other- wise, then as the ballin falling may be made to produce heat by fric- tion, we should have more heat than at first, or a creation of heat out of nothing; in other words, perpetual motion. When force is abstracted from a thermal machine we ought to lose heat. If we suppose that the degrees of heat at the lower temperature represent the same amount of force as the same number of degrees at the higher temperature; if, for instance, we suppose that a body cooling from 120° to 100°, gives off the same force as a body cool- ing from 20° to zero; this seems to be tacitly assumed by Carnot, but is probably not correct, the results of high-pressure steam and other facts indicating a contrary conclusion. If then the 20° on the lower scale do not represent an equivalent force to the 20° on the higher, we may gain the same heat in degrees in the condenser as was lost from the furnace, and yet get derived power. There is frequently a confusion between the work performed which returns to the machine, and the derived work, or that which does not return, and is used for other purposes. This is puzzling to the reader of treatises on the steam-engine, and kindred subjects, and has led to much obscurity of thought and expression. M. Seguin, in 1839, contraverted the position that derived power could be got by the mere transfer of heat, and by calculation from certain known data, such as the law of Mariotte, viz. that the elastic force of gases and vapours increased directly with the pressure, and assuming that for vapour between 100° and 150° Centigrade each degree of elevation of temperature was produced by a thermal unit, he deduced the equivalent of mechanical work capable of being performed by a given decrement of heat; and thus concluded that for ordinary pressures about one gramme of water losing one degree Centigrade would produce a force capable of raising a weight of 500 grammes through a space of one metre; this estimate is a little beyond that given by the more recent experiments of Mr. Joule. M. Seguin has, however, since the accurate and elaborate experi- ments of M. Regnault, necessarily varied his estimate, as by these experiments it appears that, within certain limits, for elevating the temperature of compressed vapour by one degree, no more than about 3;ths of a degree of total heat is required ; consequently, the equivalent multiplied in this ratio would be 1666 grammes, instead of 500. Other investigators have given numbers more or less dis- cordant, so that without giving any opinion on their different results, this question may be considered at present far from settled. M. Regnault himself does not give the law by which the ratio of Royal Institution. 319 heat varies with reference to the pressure, and is still believed to be engaged in researches on the subject, one involving questions of which experiments on the mechanical effects of elastic fluids seem to offer the most promising means of solution. One of the greatest difficulties which had presented itself to Mr. Grove’s mind, with reference to the theory of Carnot, had been one of analogy, derived from the received theories of elec- tricity. Many electrical cases might be cited in which no electricity is supposed to be lost, though a certain mechanical effort is produced by the electricity; if, for instance, a ball vibrates between a posi- tively and a negatively electrified substance, none of our electrical theories lead us to believe that any difference in the actual amount of electricity transferred would be occasioned by the ball being attached to a lever which would strike a wheel or produce any other mechanical effect. In preparing this evening’s communication an experiment had occurred to him, which, though performed with imperfect apparatus and therefore requiring verification, does, as far as it goes, support the view derived from the negation of perpetual motion, viz. that when electricity performs any mechanical work which does not return to the machine, electrical power is lost. The experiment is made in the following manner. A Leyden jar of one square foot coated surface has its interior connected with a Cuthbertson’s elec- trometer, between which and the outer coating of the jar are a pair of discharging balls fixed at a certain distance (about half an inch apart). Between the Leyden jar and the prime conductor is in- serted a small unit-jar of nine square inches surface, the knobs of which are 02 inch apart. The balance of the electrometer is now fixed by a stiff wire inserted between the attracting knobs, and the Leyden jar charged by discharges from the unit-jar. After a certain number of these (twenty-two in the experiment performed in the theatre on this occasion), the discharge of the large jar takes place across the half-inch interval; this may be viewed as the expression of elec- trical power received from the unit-jar. The experiment is now repeated, the wire between the balls having been removed, and therefore the ‘ tip’ or the raising of the weight is performed by the electrical repulsion and attraction of two pairs of balls; at twenty- two discharges of the unit-jar the balance is subverted, and one knob drops upon the other, but xo discharge takes place, showing that some electricity has been lost, or converted into the mechanical power which raises the balance. Byanother mode of expression the electricity may be supposed to be masked or analogous to latent heat, and would be restored if the ball were brought back, without discharge, by extraneous force. This experiment has succeeded in so large an average of cases, and so responds to theory, that, notwithstanding the imperfection of the apparatus, Mr. Grove places much reliance on it; indeed, it is difficult to see, if the discharges or other electrical effects were the same in both cases, why the raising the ball, being extra and the ball 320 Royal Institution. being capable by its fall of producing electricity or other force, force would not thus be got out of nothing, or perpetual motion attained. The experiment is believed to be new, and to be suggestive of others of a similar character, which may be indefinitely varied*. Thus, two balls made to diverge by electricity should not give to an electrometer the same amount of electricity as if they were, whilst electrified, kept forcibly together, an experiment which may be tried by Coulomb’s torsion balance. There is an advantage in electrical experiments of this class, as compared with those on heat, viz. that though there is no perfect insulation for electricity, yet our means of insulation are immeasu- rably superior to any attainable for heat. Similar reasoning might be applied to other forces; and many cases bearing on this subject, have been considered by Mr. Grove in his essay on the ‘‘ Correlation of Physical Forces.” Certain objections to these views were then discussed, and espe- cially some apparently formidable ones presented by M. Matteucci in a paper published by him some time ago. This distinguished philosopher cites the fact, that a voltaic battery decomposing water in a voltameter, while the same current is employed at the same time to make an electro-magnet, never- theless gives in the voltameter an equivalent of gas, or decomposed substance, for each equivalent of chemical decomposition in the cells, and will give the same ratios if the electro-magnet be removed. In answer to this objection it may be said, that in the circumstances under which this experiment is ordinarily performed, several cells of the battery are used, and so there is a far greater amount of force generated in the cells than is indicated by the effect in the volta- meter. If, moreover, the magnet is not interposed, still the magnetic force is equally existent through the whole circuit ; for instance, the wires joining the plates will attract iron filings, deflect magnetic needles, &c. By the iron core a small portion of the force is absorbed while it is being made a magnet, but this ceases to be absorbed when the magnet is made; this is proved by the recent observations of Mr. Latimer Clarke, which were fully entered into and extended by Mr. Faraday, in a lecture at the Institution (Jan. 20, 1854 t). It is like the case of a pulley and weight, which latter exhausts force while it is being raised, but when raised the force is free, and may be used for other purposes. If a battery of one cell, just capable of decomposing water and no more, be employed, this will cease to decompose while making a magnet. There must, in every case, be preponderating chemical affinity in the battery cells, either by the nature of its elements or by the reduplication of series, to effect decomposition in the vol- tameter, ard if the point is just reached at which this is effected, and the power is then reduced by any resistance, decomposition ceases: were it otherwise, were the decomposition in the voltameter * See some observations on this experiment in our last Number, p. 225. + Archives des Sciences Physiques, vol. iv. p. 380. + Phil. Mag. vol. vii. p. 197. Royal Institution. 321 the exponent of the entire force of the generating cells, and these could independently produce magnetic force, this latter force would be got from nothing, and perpetual motion be obtained. In another case, cited by M. Matteucci, viz. that a piece of zinc dissolved in dilute sulphuric acid gives somewhat less heat than when the zinc has a wire of platinum attached to it, and is dissolved by the same quantity of acid, the argument is deduced, that as there is more electricity in the second than in the first case, there should be less heat; but, as according to our received theories the heat is a product of the electric current, and in consequence of the impurity of zinc, electricity is generated in the first case molecularly in what is called local action, though not thrown into a general direction, there should be more of both heat and electricity in the second than in the first case; as the heat and electricity due to the voltaic combination of zinc and platinum are added to that excited on the surface of the zinc, and the zine should be, as in fact it is, more rapidly dissolved. Other instances are given by M. Matteucci, and many additional cases of a similar description might be sug- gested. But although it is difficult, perhaps impossible, to restrict the action of any one force to the production of one other force, and one only; yet if the whole of one force, say chemical action, be supposed to be employed in producing its full equivalent of another force, say heat; then as this heat is capable in its turn of reproducing chemical action, and, in the limit, a quantity equal or at least only infinitely short of the initial force; if this could at the same time produce independently another force, say magnetism ; we could, by adding this to the total heat, get more than the original chemical action, and thus create force or obtain perpetual motion. The impossibility of perpetual motion thus becomes a valuable test of the approach that in any experiment we may have made to eliminating the whole power which a given natural force is capable of producing; it also serves, when any new natural phenomenon is dis- covered, to enable us to ascertain how far this can be brought into re- lation with those previously known. Thus when Moser discovered that dissimilar metals would impress each other respectively with a faint image of their superficial inequalities; that, for instance, a copper coin placed on a polished silver plate, even in the dark, would, after a short time, leave on the silver plate an impression of its own device, it occurred to Mr. Grove, that as this experiment showed a physical radiation taking place between the metals, it would afforda reason for the effects produced in Volta’s contact experiment, with- out supposing a force without consumption or change in the matter evolving it. This led him to try the effect of closely approximating dises of zinc and copper without bringing them into metallic contact ; and it was found that discs thus approximated, and then quickly separated, affected the electroscope just as though they had been brought into contact. Without giving any opinion as to what may be the nature of the radiation in Moser’s phenomena, this experi- ment removes the difficulty presented by that of Volta to the chemical theory of electricity. 322 Royal Institution. The general scope of the argument from the negation of per- petual motion leads the mind to regard the so-called imponderables as modes of motion, and not as different kinds or species of matter ; the recent progress of science is continually tending to get rid of the hypotheses of fluids, of occult qualities, or latent entities, which might have been necessary in an earlier stage of scientific inquiry, and from which it is now extremely difficult to emancipate the mind : but if we can, as it is to be hoped we shall, ultimately arrive at a general dynamic theory, by which the known laws of motion of masses can be applied to molecules, or the minute structural parts of matter, it seems scarcely conceivable that the mind of man can further simplify the means of comprehending natural phzenomena. February 22, 1856.—%On certain Magnetic Actions and Affec- tions.” By Michael Faraday, D.C.L., F.R.S. All bodies subject to magnetic induction, when placed in the ordinary magnetic field between the poles of a magnet, are affected; paramagnetic bodies tend to pass bodily from weaker to stronger places of force, and diamagnetic bodies from stronger to weaker places of force. If the bodies are elongated, then those that are paramagnetic set along the lines of force, and those that are diamagnetic across them: but if these bodies have a spherical form, are amorphous, and are perfectly free from permanent mag- netic charge, they have no tendency to set in a particular direction. Nevertheless, there are bodies of both classes, which being erystal- line, have the power of setting when a single crystal is wrought into the form of a sphere, and these are called magnecrystals; their number is increasing continually; carbonate of lime, bismuth, tourmaline, &c., are of this nature. Bodies which being magnetic, set, because they are elongated, are greatly influenced in the force of the set by the nature of the medium surrounding them, and to such an extent that they not merely vary in their force from the maximum to nothing, but will often set axially in one medium, and equatori- ally in another. Yet the same bodies, if magnecrystallic and formed into spheres, though they set well in the magnetic field, will set with the same force whatever the change in the media about them, and are perfectly freed from the influence of the latter. Thus, if a crystal of bismuth formed into a sphere, or a vertical cylin- der, has, when suspended, its magnecrystallic axis horizontal, and if the various media about it, from saturated solution of sulphate of iron, up to phosphorus, through air, water, alcohol, oil, be changed one for another, no alteration in the amount of torsion force required to displace the magnecrystal will occur, provided the force of the magnet be constant, notwithstanding that the list of media includes highly paramagnetic and diamagnetic bodies ; and in such cases the measurement of the power of set is relieved from a multitude of interfering circumstances existing in other cases, and that power which is dependent upon the internal structure and con- dition of the substance is proved to be, at the same temperature, always the same. Royal Institution. 823 A consequence of magnecrystallic structure is that the same body is more paramagnetic, or more diamagnetic in one direction than in another ; and therefore it follows, that though such a crystal may have no variation in set-force, produced by change of the surrounding medium, it may have a variation produced in the absolute force of attraction or repulsion; even up to the point of being attracted in one position and repelled in another, though no change in form, or in the surrounding medium, or in the force of the magnet, or in the nature of the body itself, be made, but simply a change in the direction of the structure. This was shown by a crystal of the red ferroprussiate of potassa, which, being coated carefully with wax, was suspended from the arm of a torsion balance so that it dipped into a solution of protosulphate of iron occupying the magnetic field*. When the magnecrystallic axis was parallel to the lines of force the crystal was attracted by the magnetic pole, when it was perpendicular to the lines of force the crystal was repelled; acting like a paramagnetic and a diamagnetic in turns. No magnecrystal has yet been found having such a relation to a vacuum, or to carbonic acid (its magnetic equivalent); calcareous spar is nearly coincident with such a medium, and shows different degrees of force in the two directions, but is always a little on the diamagnetic side. Calcareous spar having a trace of iron has been found very nearly up to the desired point, on the paramagnetic side; and as these preserve the full magnecrystallic relation of the two directions, there is no reason to suppose that a crystal may not be found which may not be paramagnetic in one direction, and dia- magnetic in another, in respect of space as zero. There is every reason to believe that the general magnetic rela- tions of a magnecrystal are the same with those of the same substance in the amorphous state; and that the circumstances which influence one, influence the other to the same degree. In that case, the magnetic affections of a body might be ascertained by the examination of the magnecrystallic affections; thus the effect of heat upon bismuth, tourmaline, &c., might be examined by the set of the crystals ; and with so much the greater advantage, that short globular forms could be used, perfectly free from the magnetic influence of the surrounding media required as temperature baths, and requiring no displacement of these media with the motion of the crystal. So crystals of bismuth, tourmaline, carbonate of iron, and other bodies were suspended in baths of oil, water, &c., the temperature gradually raised and lowered, and the torsion force of the set for each tem- perature observed. With bismuth, a crystal having a force of 200 at 20° F. was reduced to a force of 70 at 300°, and the diminution of force appeared to be nearly equal in all parts of the scale for an equal number of degrees. A piece of amorphous bismuth, com- pressed in one direction, gave nearly the same amount and degree of change for the same alteration of temperature; leading us to the persuasion that the whole magnetic force of bismuth as a diamag- netic body would suffer like change. A crystal of tourmaline, which * 24 volumes of saturated solution, at 65° F., and 1 volume of water, 324 Intelligence and Miscellaneous Articles. at O° had a setting force of 540, when raised to 300°, had a setting force of only 270: the loss of force was progressive, being greater at lower than at high temperatures ; for a change from 0° to 30° caused a loss of force equal 50, whilst a change from 270° to 300° caused a loss of only 20. Carbonate of iron suffered a like change; at 0° the force was 1140, at 300° it was only 415; at the lower temperature the loss for 30° was 120 of force, at the upper it was only 34. In all these and in many other cases, both with paramagnetic and diamagnetic bodies, the magnecrystallic differences diminished with the elevation of temperature; and therefore it may be con- sidered probable, that the actual magnetic force changed in the same direction. But on extending the results to iron, nickel, and cobalt, employing these metals as very small prisms associated with copper cubes to give them weight, it was found that another result occurred. Iron, whether at the temperature of 30° or 300°, or any intermediate degree, underwent no change of force ; it remained at 300, which was the expression for the piece employed under the circumstances. We know that at higher temperatures it loses power, and that at a bright red it is almost destitute of inductive magnetic force. A piece of nickel, which at 95° had a setting power of 300, when raised to 285°, hada power of only 290, so that it had lost a thirtieth part of its force; at the heat of boiling oil, it is known to lose nearly all its force, being unable then to affect a magnetic needle. Cobalt, on the other hand, requires a far higher temperature than iron to remove its magnetic character, a heat near that of melting copper being necessary. As to lower temperatures, it was found that an elevation from 70° to 300° caused an absolute increase of the magnetic force from 293 to 333. It is evident, therefore, that there is a certain temperature, or range of temperature above 300°, at which the magnetic force of cobalt is a maximum; and that elevation above, or depression below that temperature causes a diminution of the force. The case is probably the same for iron ; its maximum magnetic force occurring at temperatures between 0° and 300°. If nickel is subject to the same conditions of a maximum, then that state must come on at temperatures below 0°: and it may be further remarked, that as the maximum conditions occur in the following order for ascending temperatures, nickel, iron, cobalt, such also is the same order for the temperatures at which they lose their high and distinctive magnetic place amongst metals. XL. Intelligence and Miscellaneous Articles. CONTRIBUTION TO THE KNOWLEDGE OF FLUORESCENCE. BY G, OSANN. l. [ HAVE succeeded in obtaining a fluid which is one of the best of fluorescent liquids, and which may be prepared with great facility and at a very small cost. Our common lampblack is well known to contain a resin which may be extracted from it by means of alcohol. Alcohol, of spec. grav. 0°853, is poured over the lampblack and left standing upon it for about a day, when a yellowish-brown fluid is Intelligence and Miscellaneous Articles. 825 obtained which possesses the property of fluorescence. In this state the fluid is rather too concentrated, and in order to obtain the proper degree of dilution I proceed in the following manner:—I take a quadrangular glass vessel with parallel walls of about an inch and a half in height, half-fill it with alcohol of the above strength, and then add the fluid. By producing a cone of light in this by means of a biconvex glass of short focus, the intensity of the colour will soon show whether the right degree of dilution has been attained. The fluorescence is greenish-blue, like that which is obtained by means of an extract of the seeds of the thorn-apple. Its behaviour towards coloured glasses is also the same. If a brownish-yellow glass be held between the eye and the fluorescent cone of light, the latter is seen almost unaltered; but it disappears almost entirely when the glass disc is brought between the lens and the fluid. 2. Relation of fluorescence to the electric light—The luminous phznomena of electricity may evidently be divided into two classes ; namely the phznomena of the electric spark, and the luminosity produced by the ignition of the bodies through which electricity passes. The former light may be produced by the sparks of the machine, or still better, because stronger, by the induction apparatus with Neef’s arrangement. I have therefore operated with the latter apparatus. ‘The induction apparatus is connected with an electro- meter in such a way, that the wire which touches the lead forms the negative electrode. When the apparatus is in action, a blue light is observed, covering the surface of the wire like a cloak. The following fluids were poured into test-tubes to a certain height; these were held at the height of the fluids to the electric light, and looked into from above:—1. A solution of sulphate of quinine in water. 2. A decoction of the bark of the horse- chestnut. 3. An alcoholic extract of the seeds of the thorn-apple. 4. A similar extract of turmeric root. 5. An alcoholic extract of litmus (dispersed yellow light). 6. A solution of chlorophyll in alcohol. The result of these experiments was, that the first five fluids were fluorescent, but no fluorescence could be detected in the sixth. A repetition of this experiment gave the same results. From this it would appear that the electrical light is deficient in the rays which produce red in the solution of chlorophyll. I now instituted a series of experiments in order to ascertain the effects of the light of a platinum wire ignited by the passage of an electrical current. For this purpose a platinum wire of an inch anda half long was fixed in such a manner, that porcelain saucers con- taining the above-mentioned fluids might be placed beneathit. The wire was then brought to a red heat by the current, and the fluids placed under it one after another. These experiments were made in a camera-obscura lined with black, and the result was entirely negative. They were then repeated by pouring portions of the fluids into test-tubes, holding them to the ignited wire, and looking in from the top. Under these circumstances also no fluorescence could be detected. Only the fluid No. 5 glittered with a reddish light, but this is its ordinary colour. The experiment showed that the light of the ignited wire contained many red rays. This fact agrees 326 Intelligence and Miscellaneous Articles. with the observations which I made by holding coloured papers under the wire.—Poggendorff’s Annalen, vol. xevii. p. 329. EXAMINATION OF THE GREEN MATTER OF THE TRUE INFUSORIA. BY THE PRINCE OF SALM-HORSTMAR. The author commences by stating that his former communication upon the green colouring matter of the Infusoria* was founded upon an error, as the objects investigated by him were not Infusoria but minute Algz (Coccodea viridis). He has now investigated the green matter of Huglena viridis. The animals, which were very lively, when collected on a filter, dried, and extracted with alcohol, furnished an emerald-green extract with a yellowish tinge, which gives a blood-red dispersed light. ‘The extract evaporated to dryness at a gentle heat presented the follow- ing properties :— It does not dissolve perceptibly in water, even when heated. Ammonia dissolves it when heated with a yellowish-green colour, and the solution is somewhat turbid. It is somewhat soluble in solution of caustic potash with the assistance of heat; the solution is yellowish-green. Sulphuric ether dissolves it very readily with an emerald-green colour. ‘This solution exhibits a very strong blood-red dispersion of both sun- and candle-light. It does not leave a coloured residue when left to spontaneous evaporation in an open test-glass, so that the coloured matter possesses the remarkable property of being vola- tilized with ether. It dissolves readily in oil of turpentine with a green colour, and produces a blood-red dispersion of light. The behaviour of this dry green matter obtained from the alco- holic extract, when heated in an open platinum cup, is very remark- able. Thus when it is gently heated, without bringing the platinum cup to redness, it evaporates without fusing, and diffuses an odour of fish. It leaves a blackish-brown residue, which gradually evapo- rates by heat (if the platinum cup be so heated as not to reach igni- tion), but does not take fire even when the platinum is heated to redness. Behaviour of the green alcoholic solution towards Reagents.—The addition of an equal volume of water renders it slightly turbid at first. ‘The turbidity is green; and on boiling, all becomes clear and green; even after the addition of five volumes of water it does not again become turbid after boiling, and forty volumes of water may then be added without perceptible turbidity. Acetic acid produces a green turbidity. Acetate of lead also causes a green turbidity, which afterwards becomes a green precipi- tate; this is readily soluble in alcohol, giving a green colour without red dispersion. Acetate of copper causes no turbidity ; when heated there is a slight turbidity. Nitrate of silver gives no turbidity, but after standing for a few hours a greenish-black precipitate. The supernatant fluid retains * See Phil. Mag. October 1855, p. 309. M eteorological Observations. 327 its green colour and red dispersion, but in about twelve hours it becomes pale and the precipitate increases. Nitrate of lime produces no turbidity, but the colour becomes olive-green, and there is no longer any red dispersion. After stand- ing twelve hours a precipitate is formed and the colour of the liquid disappears. Muriate of alumina dissolved in alcohol gives a green turbidity, and the fluid loses its colour. After standing some hours a greenish, not flocculent, precipitate is formed. Muriatic acid strikes an olive-green colour. On litmus paper it has neither an acid nor an alkaline reaction. The green colouring matter in Huglena viridis is therefore essen- tially different from that of the Algz, as well as from the chloro- phyll of the Phanerogamia, and of the green mosses.—Poggendorff’s Annalen, vol. xcvii. p. 331. METEOROLOGICAL OBSERVATIONS FOR FEB. 1856. Chiswick.—February 1. Light clouds: frosty. 2. Cloudy. 3. Frosty: fine throughout. 4. Overcast: slight rain. 5. Very fine: boisterous at night. 6. Densely clouded: boisterous. 7. Uniformly overcast: rain. 8. Densely over- cast: fine: cloudy. 9. Exceedingly fine. 10. Cloudy. 11. Foggy: rain: over- cast. 12. Rain: fine: rainatnight. 13. Rain: showery throughout. 14. Rain: fine. 15. Cloudy: very fine: foggy at night. 16. Foggy: very fine: foggy. 17. Hazy: overcast: foggy at night. 18. Overcast: slight snow. 19. Hazy: cold and raw. 20. Cloudy and cold throughout. 21. Slight rain: small hail occa- sionally. 22. Overcast: slight rain. 23. Fine throughout: cloudy at night. 24. Fine: overcast: clear and frosty. 25. Overcast throughout. - 26. Cloudy: slight rain. 27. Overcast. 28. Very slight drizzle: overcast: cloudy. 29. Foggy: cloudy : frosty. Mean temperature of the month ........... Bie Mew Sette 54 Mean temperature of Feb. 1855 — ..........sseeeeeee pevedensres ted 28 -01 Mean temperature of Feb. for the last thirty years ce eesccceces 38 °71 Average amount of rain in Feb. — .......ee..seeseeesereereces ee... 1°543 inch. Boston.— Feb. 1—3. Fine. 4,5. Cloudy. 6. Rain a.m.andp.m. 7,8. Cloudy: rain A.M. 9. Cloudy. 10. Cloudy: raina.m. 11. Cloudy: rainp.m. 12. Rain aM. 13. Cloudy: rainp.m. 14,15. Fine. 16—22. Cloudy. 23,24. Fine. 25—28. Cloudy. 29. Foggy. Sandwick Manse, Orkney.—Feb. 1. Cloudy a.m.: showers, thaw p.m. 2. Cloudy A.M.: fine p.m. 3. Fine, bright a.m.: fine, clear p.m. 4. Fine, cloudy a.m.: fine, clear y.m. 5. Fine,drops a.m.: fine, cloudye.m. 6. Bright a.m. : rain P.M. 7. Bright a.m.: showers p.m. 8. Cloudy a.m.and p.m. 9. Drops A.M. : clear P.M. 10. Bright a.m. : clear, showers p.m. 11. Bright a.m.: clear, finep.m. 12. Rain A.M.: Showers P.M. 13. Bright a.m.: cloudy r.m. 14. Snow-showers a.m. : showers p.M. 15. Rain a.m.: cloudy p.m. 16. Drizzle, showers a.m. : drizzle P.M. 17. Damp a.m. and p.m. 18. Cloudy a.m. and p.m. 19. Cloudy, frost a.m. : clear, fine p.m. 20. Bright a.m.: cloudy, fine p.m. 21. Bright a.m.: clear p.m. 22. Bright a.m.: showers, clearp.m. 23. Bright a.m.: cloudy r.m. 24. Cloudy A.M.: clear P.M. 25. Rain a.m.: showers, clear, aurora p.m. 26. Cloudy a.m. : drizzle p.m. 27. Showers a.m.: fine, cloudy p.m. 28. Drizzle a.m.: damp P.M. 29. Cloudy a.m. and p.m. Mean temperature of Feb. for previous twenty-nine years ... 38°01 Mean temperature of this month ..,..s.scccececscssesscsceescsees 40 84 Mean temperature of Feb. 1855 —.....2..:.cscececsoscccecscsvecse 31 -64 Average quantity of rain in Feb. for fifteen previous years ... 3°25 inches. The storm which raged so violently in the South of Scotland on the 6th and 7th did not reach Orkney or the North of Scotland, but again we had this month as well as during the gale of last month a great fall of the barometer, which stood at 28°49 on the 6th at midnight. tv.% seereeeee fo, +o, 00.1 | £9.0 | *) 10, ane wee eeeeee Io. wee teeeee ceeueeeee gz. [tteeeests go. leeeesecee rl. wee eeeeee gz. ZO, a. oxy see eweeee seem ee eee eeeserene gf. tO. n io) wo Be | ¢ ea | 8 a 5 10. Io, ZO, oz. So. oz. go. ZO. 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[FOURTH SERIES.] MAY 1856. XLI. On a peculiar case of Colour Blindness. By Joun Tynvatt, F.R.S. &c.* CASE of colour blindness has been recently brought under my notice by Mr. White Cooper, of so singular a character that I think even the brief description of it which the pressure of other duties permits me to give will not be without interest to the readers of the Philosophical Magazine. Out of eleven hundred and fifty-four cases examined by Dr. George Wilson of the University of Edinburgh, and recorded by him in his truly interesting and valuable work on Colour Blind- ness}, only one instance was found in which the sufferer was aware of the loss he had sustained. This was the case of a medical practitioner in Yorkshire, who in November 1849 was thrown from his horse. “ After rallying from the collapse which immediately succeeded the accident, he suffered from severe pain in the head, delirium, mental excitation approaching almost to mania, loss of memory, and other symptoms of cerebral disturb- URE On recovering sufficiently to notice distinctly objects around him, he found his perception of colours, which was for- merly normal and acute, had become both weakened and per- verted, and has since continued so. ... Flowers have lost more than half their beauty for him, and he still recalls the shock which he experienced on first entering his garden after his re- * Communicated by the Author. + At page 137 I find some observations of mine referred to. 1 would here remark, that whatever observations or experiments I have hitherto made on this subject were merely repetitions or modifications of those of Dove or Helmholtz, whose excellent memoirs I had the pleasure of intro- ducing into this country. Phil. Mag. 8. 4. Vol. 11. No. 73. May 1856. Z 330 Prof. Tyndall on a peculiar case of Colour Blindness. covery, at finding that a favourite damask rose had become in all its parts, petals, leaves, and stem, of one uniform dull colour ; and that variegated flowers, such as carnations, had lost their characteristic tints.” The case of Captain C., which I have to describe, is one of these rare instances. The sufferer isa seaman, and ten or twelve years ago was accustomed, when time lay heavy on his hands, to occupy it by working at embroidery. Being engaged one after- noon upon a piece of work of this description, and anxious to finish a flower (a red one, he believes), he prolonged his labours until twilight fell, and he found it difficult to select the suitable colours. To obtain more light he went ito the companion, or entrance to the cabin, and there continued his needlework. While thus taxing his eyes, his power of distinguishing the colours suddenly vanished. He went upon deck, hoping that an increase of light would restore his vision. In vain. From that time to the pre- sent he has remained colour blind. My first examination of Captain C. took place in the house of Mr. Cooper. Being furnished with specimens of Berlin wool, such as that with which the patient had been accustomed to work, I placed before him a skein which he at once, and cor- rectly, pronounced to be blue. For this colour he has a keen appreciation, and I have never known him make a mistake re- garding it. Two bundles of worsted, one a light green and the other a vivid scarlet, were next placed before him: he pronounced them to be both of the same colour; a difference of shade was perceptible, but both to him were drab. A green glass and a red glass were placed side by side between him and the window : he could discern no difference between the colours. A very dark green he pronounced to be black; the purple covering of the chairs were also black; a deep red rose on the wall of the room was a mere blotch of black; fruit, partly of a bright red and partly of a deep green, were pronounced to be of the same uni- form colour. A cedar pencil and a stick of sealing-wax placed side by side were nearly alike ; the former was rather brown, the latter a drab. Time, I found, made a difference: slate colour and red were placed side by side; on first looking at them Captain C. thought them different shades of the same colour, but after looking at them for half a minute even this difference of shade disappeared. By the production of subjective effects, such as looking long at an object through a coloured glass, and then removing the latter, his judgement of colours could also be made to vary in a slight degree. My second examination of Captain C. took place in the theatre of the Royal Institution ; and on the day he ealled upon me I happened to be using the electric light, rendered contmuous by Prof. Tyndall on a peculiar case of Colour Blindness. 331 Duboscq’s lamp. A portion of the light was permitted to pass through a bright green glass and was received upon a screen; no change of colour was perceived: the space on which the green light fell was merely a little less intensely illuminated than the remaining portion of the screen. Lycopodium was shaken upon glass: the electric hght looked at through such a glass gives, as is known, a series of brilliantly coloured rings : to Captain C., how- ever, no colour was manifest, merely light and obscure rings fol- lowing each other in succession. A spectrum was cast upon the screen in which all the prismatic colours shone vividly ; to Cap- tain C. only two colours were manifest, namely blue and whitish- yellow. The outline of the spectrum was the same to him as to me; all that gave me light gave him light also; but in his case the red, orange, and green were so modified as to produce the uniform impression of whitish-yellow. In some cases of colour blindness, where the sufferer confounds red with green, it is diffi- cult to say whether he takes the red for a green or the green forared. In the present case neither of these expresses the fact ; neither red nor green is seen, but both of them are reduced to a colour different from either. Captain C. assured me, that, previous to the circumstance re- lated at the commencement, he was a good judge of colours, so that in pronouncing upon any colour he has an aid from memory not usually possessed by the colour blind. Indeed I had myself an opportunity of reviving his impression of red. A glass of this colour was placed before his eyes while he stood close to the electric lamp: on establishing the light, he at once exclaimed, “that is red!” He appeared greatly delighted to renew his acquaintance with this colour, and declared that be had not seen it for several years. The glass was then held near the light while he went to a distance, but in this case no colour was manifest ; neither was any colour seen when a gas-lamp was regarded through the same glass. The intense action due to proximity to the electric light appeared necessary to produce the effect. “You gave the eye a dram,” observed a gentleman to whom I deseribed the case: the figure appears to be a correct one. Captain C.’s interest in this experiment was increased by the fact, that the Portland light, which he has occasion to observe, has been recently changed from green to red, but he has not been able to recognize this change. The fave in the fore-cabin of a vessel of his own which he now commands happens to be sixpence, and he is often reminded by the passengers that he has not returned their change. ‘The reason is, that he confounds a sixpence with a half-sovereign, both being to him of the same colour. A short time ago he gave a sovereign to a waterman, believing it to be a shilling. Z2 332 Prof. Tyndall on a peculiar case of Colour Blindness. It was my intention to make a guess at the cause of colour blindness in the case above described; but guesses, without the means of verifying them, are so unsatisfactory, and so apt to pro- duce fruitless discussion, that for the present at least I will con- fine myself to the statement of the facts. Two other cases of a different nature were also brought under my notice by Mr. Cooper, and may, on account of their rarity, be worthy of a brief reference. The first is that of a little girl, about seven years old, the development of whose eyes had been arrested before birth. The child’s sight, however, though imperfect, was sufficient to enable her to distinguish colours with accuracy. When the spectrum was displayed before her, she ran her fingers promptly over the colours and named them correctly. She could also read large print. The phenomena of irradiation presented themselves to her as they did to me; an incandescent platinum wire became thicker as she receded from it. As far as I could judge, the retina was perfectly healthy. I placed her within a foot of the coal-points of the electric lamp, and establishing the current, allowed the full splendour of the light to fall upon her eyes: she never even winked, but looked steadily into the light, and stated that she did not feel the shghtest inconvenience. This perhaps was due to the partial opacity of the humours of the eye. The position of the iris in her case was marked by a few gray spots, and the pupil had no definite boundary. The eyes were, as might be expected, out of all proportion with the growth of the child: the arrestation of development extended to the teeth also, which caused the child to appear much older than she really was. She was very intelligent ; and her mother, who accompanied her, was a healthy intelligent woman, with fine brown eyes. She stated to me, that neither in her own nor her husband’s family did a case of the kind ever occur; and yet she had four children, and the whole of them, without exception, were afflicted in a similar manner. The second case is that of a distinguished artist, also sent to me by Mr. Cooper. Several months ago he noticed, on looking at any distant point of light, a whitish luminosity spreading round the point, and first observed this appearance on the occasion of rubbing his right eye somewhat severely. As time advanced, the luminosity merged into a series of coloured rings which encircled the luminous point ; and as these were becoming brighter and larger, his fears of the ultimate blindness of the eye became excited. He had consulted several eminent oculists, and had, I believe, been subjected to severe treatment, on the sup- position that the retina was the seat of the malady. The co- loured curves were not perfect circles. I placed Mr. S. upon his Prof. Tyndall on a peculiar case of Colour Blindness. 333 knees on the floor, and caused him to look upward at the electric lamp: in this position the upper portion of the pupil was shaded by the eyelid, and the coloured rings totally disappeared. I then caused him to stand upon a table and to look down upon the lamp: in this position the under portion of the pupil was shaded by the lid, and the colours were displayed in all their brilliancy. Mr. S.’s left eye was totally free from all defects of this kind. I shook a little lycopodium on glass, and presented it before his left eye. The system of rings this revealed to his good eye was precisely similar to those presented to the- other. The lycopodium rings were smaller, but in other respects the same as those of the right eye, with the exception of the diver- gence of the latter from the circular form mentioned above. I ventured to express my doubts to Mr. S. as to the retina being the seat of the disease, and to comfort him with the hope that the augmentation of the rings in brilliancy and magnitude pointed rather to the diminution than to the increase of his malady. I will leave it to physiologists to say what possible particles within the humours of the eye could act the part of the spores of lyco- podium without the eye; but I entertain very little doubt that it is from the presence of such particles, a thin film, or some equivalent optical cause, and not from any affection of the retina, that the effects observed by Mr. S. arise. If this be the case, it simply shows how necessary a knowledge of physics is to medical men. I now regret that want of time prevented me from enter- ing further upon the examination of the case last referred to. Royal Institution, April 1856, With reference to the case of Captain C., Mr. Cooper make: the following remarks :—“ In this case the symptoms are clearly referable to the intense strain to which the eyes were subjected for a long period, and under unfavourable circumstances—a strain beyond endurance, and which seems to have deprived the retina of the power of appreciating impressions. Such a con- dition is little amenable to treatment. After the Great Exhi- bition of 1851, instances came under my notice in which the sensibility of the retina was temporarily blunted by the excite- ment to which it was exposed in that brilliant scene. Here the sensibility to impressions of colours was only suspended, and gradually returned; but it is to be feared, that, in the case nar- rated by Professor Tyndall, it may be regarded as extinguished : the vibrations of the coloured rays produce no responsive action in the nervous fibrille.”—W. C. [ 884 ] XLII. Researches on the Methods of preserving the Sensitiveness of Collodion Plates. By Joun SrituerR and Witiiam Crooxkgs.* 1 te is now nearly two years since we had the honour of pre- senting to the photographic world our first experiments made with the view of preserving the sensitiveness of collodion plates. In the Philosophical Magazine for May 1854 (an abs- tract appearing in the Photographic Journal of that month) we communicated the possibility of securing this end by taking advantage of the deliquescent nature of certain neutral salts, which, by retaining water in the film, enabled us to prolong or defer the exposure of the sensitive plate for a length of time which was not practicable by the ordinary collodion process. For this purpose we proposed the use of the nitrates of zinc, manganese, lime or magnesia, and, as the type of a class of sub- stances equally suitable in the organic kingdom, glycerine ; sugar also had been tried, but with no good result. In conse- quence of public attention being again drawn to glycerine, by the lecture recently delivered before the Society of Arts, we think it but right to assert our claim of priority in suggesting the application of this body to the purpose under consideration. We quote from the article of May 1854. “‘ Glycerme at first seemed to promise very good results, but the principal difficulty was the necessary impurity of the commercial product, in con- sequence of its being obtained from the exhausted leys of the soap boilers.” Now, however, that an improved process of manufacture has been introduced at the works of Price’s Patent Candle Company, where it is obtained as a bye product in the decomposition of fatty matters by high-pressure steam, it became a point of interest to determine whether the purer article might not well serve the object in view. With this intention we pro- cured a sample of Price’s glycerine as soon as it became an article of commerce, and although the result of our experiments coincides to a certain extent with those of Mr. Pollock and others, we nevertheless think it worth while to specify the par- ticular points of difference in manipulation, some of which will, we believe, materially facilitate the preparation of the plates in this way. Our first care was to ascertain the action of glycerine upon an aqueous solution of nitrate of silver. For this purpose, a mixture was made and divided into two portions, one of which was ex- posed to a full southern aspect, and the other carefully protected from every gleam of light; after a few days a thin but distinct coating of metallic silver was found lining the interior of the * Communicated by the Authors. * Method of preserving the Sensitiveness of Collodion Plates. 335 glass vessel in the light, while very slight, if any, evidence of reducing action was appreciable in that kept in the dark, even after the expiration of a month. Finding the action of light to exercise this influence, we determined to keep separately, as far as possible, these two necessary ingredients in the process. With regard to the degree of concentration of the glycerine, the sample made use of has a specific gravity of 1:23 ; this we have employed in its original state, and mixed with various proportions of water ; we perceive no great difference in the results, but are inclined to prefer its employment with but little dilution with water. The process we have been led to adopt is the following :—The glass plate, cleaned with especial care (by treatment, first, with a hot solution of common washing soda, and subsequently with strong nitric acid), is coated with iodide of ammonium collodion in the usual way, and made sensitive by immersion in the ordi- nary silver bath (80 grains of the nitrate to 1 ounce of water ; perfectly saturated with iodide of silver*, so that the plate may be left its full time without fear of dissolving the sensitive film) ; after remaining here three or four minutes, the excited plate is transferred to, and immersed for an equal time in, a washing bath of pure distilled water; or instead of this bath we have sometimes used a stream of water from the “syringe bottle,” the object being to remove the great excess of free nitrate of silver from the sensitive film. So prepared, the plate is ready to receive the glycerine treat- ment. For this purpose we require, besides Price’s glycerine, sp. gr. 1:23 or thereabouts, a dilute solution of nitrate of silver (one grain of nitrate to the ounce of water). When about to be used, an intimate mixture is made in the proportion of three parts by volume of glycerine to one of the silver solution, and poured on to the surface of the washed collodion plate, its action being assisted by transferring, some two or three times, to and from the measure glass; after five minutes’ contact the plate has to be well drained, and placed in a nearly vertical position on blotting-paper, to absorb the large excess of glycerine from its surface. It will then be in a fit state for receiving the impres- sion in the camera, a process which may either be performed immediately or deferred for a period of at least twenty-four days, the longest trial to which we have as yet submitted the plates. * This is readily effected by dissolving the total weight of nitrate of sil- ver in one-fourth of the bulk of water to be ultimately employed; a grain or so of iodide of potassium dissolved in a little water is now added, to precipitate an equivalent amount of iodide of silver, with which the solution will be saturated on stirring; the remaining bulk of the water is then added. After allowing time for subsidence, the solution may be filtered without difficulty. The addition of a few drops of glacial acetic acid to a large bath is an improvement. 336 Messrs. J. Spiller and W. Crookes’s Researches on the In regard to sensitiveness, they will, if used immediately, be found very little inferior to plates prepared in the ordinary way; we have, however, detected evidence of slight deterioration in pro- portion to the length of time the exposure has been deferred. In cases where it is necessary to keep the plates ready excited through a protracted interval, we have devised a convenient plate-box to store them in, which may easily be made by replacing the wooden grooves in an ordinary plate-box by two corrugated sheets of gutta percha, and laying a square of thin caoutchoue at the bottom for the glasses to rest upon. Such a box will always require an outer covering to protect its contents from every gleam of light, the necessity for which precaution, as also that of excluding injurious gases, such as ammonia and sul- phuretted hydrogen, will be sufficiently obvious without further comment. Before proceeding to develope the latent image on the glycerine plate, it is only necessary to immerse it for two or three minutes m the 30-grai nitrate of silver bath, when the solution of pyro- gallic acid or protosalt of iron may be applied as usual ; the remaining part of the process, fixing, &c. being conducted in the ordinary manner. The negative pictures resulting from this mode of treatment have not, in our hands, been found wanting either in intensity or in gradation of tone ; they are in fact fully equal to the results of the collodion process as usually practised. If considered desirable, a bath of the mixture of glycerine and nitrate of silver may be employed, instead of the mode of application recommended above; in that case it will be neces- sary to protect the fluid from the light, so as to avoid the depo- sition of metallic silver; and on that account, to make use of a covered gutta-percha in preference to a glass bath for containing the solution. The remarkable purity of Price’s glycerine, its absolute freedom from chlorides (and sulphates), renders the plan of mixing only as required for use far more practicable than would otherwise have been the case, had filtration been neces- sary. Any excess of the preservative fluid, remaining after the preparation of a certain number of the plates, should be kept on stock (in a dark place), and may be again employed for the same purpose, after filterimg and adding a httle pure glycerine to counterbalance the accession of a small proportion of nitrate of silver from each successive plate. In addition to the glycerine process, we have, at intervals, given some attention to the other means of preserving collodion plates, and have succeeded in attaining that object by several other methods, as also in improving the processes already de- tailed in our former communications. Methods of preserving the Sensitiveness of Collodion Plates. 2337 Bearmg in mind the qualities requisite to fulfil in the best manner the functions of a preservative agent, it occurred to us that it might be possible to find a body having in itself the power of rendering the collodion film sensitive to light, or at least of sustaining it in that condition, and at the same time possessing deliquescent properties; substances having these two characters combined are presented in the fluoride and silico- fluoride of silver. To put this supposition to the test of expe- riment, we prepared these compounds (by dissolving freshly pre- cipitated carbonate of silver in hydrofluoric and hydrofluosilicic acids respectively), and used their solutions, in place of the ordinary nitrate of silver bath, for exciting the iodized collodion film. Plates so treated readily became coated with a layer of iodide of silver, which seemed to be equally sensitive to light, whether produced by this or the method commonly employed ; they had also the power of retaining a moist surface; but, un- fortunately for the present object, it was found that a strong solution of fluoride of silver, like that of the nitrate, has the pro- perty of dissolving off the precipitated iodide of silver, destroy- ing it by forming the small holes so well known in the ordinary collodion process. Meeting with this result, we determined to try their application in a more dilute form, after exciting the plate in a preliminary nitrate of silver bath; but by this mode of treatment also we were unsuccessful, being unable to preserve the sensitiveness by a quantity which was insufficient to exercise a destructive influence on the film. This difficulty, added to that experienced in the preparation of the fluoride in a neutral condition, any excess of hydrofluoric acid being objectionable on account of its property of etching the glass, and on the other hand, the slightest alkaline reaction rendering it extremely diffi- cult to obtain clear pictures on development, deterred us from pursuing the subject further in this direction. Compelled, therefore, to return to the principle originally adopted, viz. the use of nitrate of silver in conjunction with a deliquescent salt, sufficient in amount to prevent its crystallizing or even concentrating beyond a certain limit upon the plate, we sought only to improve the processes already before the public. A longer experience with the nitrate of magnesia has demon- strated the difficulty of preparing this substance on a large scale, free from an impurity very inimical to its successful application —the nitrite of magnesia; the presence of this latter, by giving rise to the formation in the film of the nitrite of silver, a body prone to spontaneous decomposition even at ordinary tempera- tures, must necessarily introduce a condition unfavourable to the ultimate result. To effect the conversion of the nitrite* into * The presence of nitrous acid is easily recognized by Dr. Price’s test. It is applied by adding a mixture of dilute hydrochloric acid and iodide of 338 Method of preserving the Sensitiveness of Collodion Plates. nitrate, and at the same time to neutralize the invariable alka- linity of the commercial substance, we prefer to employ nitric acid highly diluted, and added gradually to the magnesian salt, previously dissolved in water, until a very faintly acid reaction is communicated to blue litmus paper; any decided excess of acid must be avoided, its presence being certainly antagonistic to a high state of sensibility. The proportions we have generally adopted are,— Nitrate of magnesia . . . 4 ounces. Nitme-art Se en. 3. UATE, San, Nitrate of silver. . . . . 12 grains. Waters". <2 Sarees ett le OUNCES The silver salt must be added after the neutralization has been performed, any precipitated chloride resulting from impurity being removed by filtration. Before use it should be ascer- tained that the solution really contains silver, by transferring a few drops of the clear fluid to a watch-glass, and mixing with common salt, when a milky turbidity, however slight, will indi- cate the presence of a sufficient amount of silver to sustain the sensitive condition of the plate. The solution of nitrate of magnesia may, if preferred, be pre- pared by double decomposition between sulphate of magnesia and nitrate of baryta, mixing them in the proportion of their chemical equivalents, and filtering off the insoluble sulphate of baryta. The only advantage in practising this method is the certainty of obtaining a neutral solution when the pure crystal- lized salts have been employed; it will, however, be found im- possible to exclude a slight excess of one or other of these salts ; a small quantity of sulphate of magnesia was left in the solution used in our experiments, but it did not appear to exert any in- jurious influence. A small proportion of nitrate of silver must as usual be added before use. The double nitrate of magnesia and ammonia we have also employed with very good results. It was prepared by measuring out two equal volumes of diluted nitric acid, saturating the one with carbonate of magnesia, and the other with carbonate of ammonia, and then mixing; the solution required the addition of a few drops of very weak nitric acid to render it neutral, and a small quantity of nitrate of silver. Nitrate of manganese, prepared either by dissolving the pre- cipitated carbonate in dilute nitric acid, or by double decompo- sition between equivalent quantities of crystallized sulphate of manganese (MnO, SO?+4HO) and nitrate of baryta, gives, upon potassium, with a little starch paste, to the nitrate of magnesia dissolved in water; in the event of its containing nitrite, a blue colour or precipitate will appear, according to the amount of this impurity that may be present. On a General Law of Electrical Discharge. 339 addition of a small proportion of nitrate of silver, a solution well fitted for use as a preservative agent. The colour of the liquid is a pale rose-red. The nitrate of copper has also been tried for our purpose, but did not give promising results, the sensitive- ness of the collodion film being greatly impaired by the highly acid nature of this salt. Finally, we have employed with excellent results the nitrate of nickel, which, however, requires some care in its preparation. The method we have found most successful consists in dissolving the metal in the smallest possible quantity of nitric acid, and adding to the solution highly dilute aqueous ammonia, sufficient in amount to precipitate a small portion of the oxide of nickel ; this being filtered off, the liquid will have an alkaline reaction : nitric acid is now added until nearly neutralized, and the last traces of alkalinity removed by acetic acid, a slight excess of which is an advantage. Nitrate of silver should now be intro- duced in the proportion of 2 per cent. of the nickel originally employed. The above mode of proceeding will obviously give rise to the production of a certain quantity of nitrate of ammonia ; this, however, combines to form a double nitrate of nickel and ammonia, a salt possessing deliquescent properties, and appa- rently equally suitable for our purpose. The colour of this agent, bright green, suggests the possibility of employing it with advan- tage in cases where green foliage has to be represented in juxta- position with objects reflecting more active photographic rays. Of all the substances known to be applicable to the preserva- tion of collodion plates, we believe that the use of glycerine will give less trouble to those unaccustomed to chemical manipula- tion, and will be generally preferred from the greater certainty of its results. We have nevertheless thought it worth while to record our experience in respect to the other agents severally enumerated, even where, as in the case of fluoride of silver, they have not led to successful results, believing that a statement of the conditions under which we have endeavoured to employ them may save loss of time to future experimentalists in the same direction. London, April 14, 1856. XLII. On a General Law of Electrical Discharge. By Sir W. Syow Harris, F.2.S.* [ With a Plate. ] 1. JN a memoir on Electrical Accumulation, presented to the members of the Plymouth Philosophical Institution so long since as the year 1826, and printed m a volume of their * Communicated by the Author. 340 Sir W. Snow Harris on a General Law of Transactions for 1830, I announced a law of electricity of great generality, viz. that the heating effect of the ordinary electrical discharge transmitted through a metallic wire placed in the cir- cuit is as the square of the accumulation, and is entirely depend- ent on the quantity of electricity discharged, without any regard to the intensity indications of the ordinary electrometers. Con- sequently through whatever interval of air the discharge can pass, as measured by a Lane’s electrometer, the heating effect of the momentary current in the wire will, with a similar circuit, be always the same for the same quantity of electricity,—a de- duction which has since been fully verified by further discoveries in electricity*. M. De la Rive, for example, found the heating effect of the voltaic current, and which he estimated by the beautiful helical thermometer of Brequet, wholly dependent on the quantity of electricity+. Faraday also shows, Experimental Researches (366.), that ‘if the same quantity of electricity pass through the galvanometer, the deflection of the needle is always the same whatever may be the electrical intensity ;” and again (704.), in the case of electro-chemical decomposition, ‘ the force of a given quantity of electricity is always the same, notwith- standing the greatest variations of intensity.” Thus the law which I had previously announced has been so far satisfactorily confirmed by the subsequent investigations of two philosophers, whose admirable researches have enriched this branch of physics. 2. Although my original announcement is thus sanctioned by experimental evidence of the highest authority, yet M. De la Rive, in his valuable work, Trazté de I’ Electricité, recently pub- lished, has quoted largely from certain memoirs of M.le Professeur Riess of Berlin, who thinks he has shown the fallacy of my an- nouncement, “la fausseté de cet énoncé.” Repeated experiments, he says, “have informed me that the elevation of temperature in a metallic wire by the electrical discharge is proportional to the quantity of electricity accumulated multiplied by its density, or what comes to the same thing, proportional to the square of the quantity divided by the extent of the battery {;” so that his formula would be T= = in which T is the elevation of tempe- rature, Q the quantity, and s the extent of the battery. At p- 116, M. Riess attributes my failure in arriving at the same conclusion as himself, to a want of accuracy in my experiments, * See also Phil. Trans. for 1834, p. 225. + Ann. de Chim. et de Phys. vol. lii. p. 177 and 183. { Ann. de Chim. vol. xix. p. 113; and Dela Rive, Traité de ? Electricité, vol. ii. pp. 154 and 162. Electrical Discharge. 341 and the imperfect construction of my instrument, viz. the “ thermo-electrometer*.” 3. As this is a question of much physical interest, more especially in the present progressive state of electricity as a science, and as any observation of so skilful and profound a philosopher as M. Riess merits great consideration, more especially when counte- nanced by so distinguished a writer as M. De la Rive, I am desirous to submit, for the consideration of those engaged in elec- trical inquiries, some further remarks and experiments relative to the exceptions thus taken to the accuracy of my early announce- ments. I am led to take this step, beimg under the impression that I may thereby benefit science, and throw some further light on this interesting subject. I think it will be found that M. Riess, on referring to my inquiries, has not clearly appre- hended the phznomena in question, so prominently set forth by M. De la Rive. I may perhaps further claim, and not unrea- sonably, the privilege of seeking to obtain some little justice for myself, in reference to the remarks of M. Riess, viz. that my ex- periments have proved “ unfruitful,” and that he has “ shown the falsity of my announcement,” observations which seem to imply a belief in the infallibility of his own deductions, and which he thus erects into a sort of standard of value with which to com- pare mine. I think, however, it will be found that the results arrived at by M. Riess, and quoted by M. De la Rive, are really no others than those which I had myself previously obtained and published in my memoir above mentioned (1) ; and I trust to be enabled to satisfactorily explam in what consists the difference in our interpretation of these results. 4. First, however, I must beg to be allowed to submit a few brief explanatory observations on the nature and construction of my instrument—the thermo-electrometer, which M. Riess ima- gines to have been so imperfect in my hands as to induce him to place it under what he supposes to be a new form. The in- strument has been much used, not only in this country but also on the Continent, and has without doubt rendered good service to the progress of electrical research; it is, in fact, upon this instrument that much of the real value of M. Riess’s inquiries depend. The thermo-electrometer, Plate III. figs.1, 2,3, was first invented + by me so long since as the year 1820, now more than thirty-five years since, although M. De la Rive conceives he was the first person who employed a contrivance of this kind}. My original instrument will be found in a quarto work, which | published in 1823, relative to the effectual protection of the British Navy from * Ann. de Chim. vol. \xix. p. 113; and Traité de l Electricité, De la Rive, vol, ii. p. 154. t+ Traité de V Electricité, vol. i. p. 31. 342 Sir W. Snow Harris on a General Law of lightning*, where it is figured and described. Fig. 1 represents this original construction, in which apvz is the glass thermometer ball, about 4: inches in diameter, and pn a fine metallic wire passed air-tight across its centre. This wire is hermetically fixed through the ball by means of short metallic studs, attached to plates of metal cemented in and about two holes drilled on op- posite sides through the glass; the studs are perforated for the passage of the wire, and are covered by flattened balls of metal screwed air-tight over them. a is the thermometer tube, having a divided scale attached to it ; its lower extremity, d, is sustained in a reservoir of glass, w, containing a coloured liquid. The instrument is prepared for experiment by first drawing out a small portion of air from the ball, ap v n, by means of heat, and then immersing the lower extremity, 0, of the tube in the coloured fluid; as the ball cools, the fluid ascends along the scale; its precise position is regulated by a small valve, v, cemented in a hole drilled through the upper part of the tube, in the way already described. When an electrical discharge of a given force is passed through the wire, the fluid descends along the scale and marks the com- parative degree of heat excited in the wire. For the better ad- justment of the fluid to the zero-point of the scale, the latter is so contrived as to be moveable on the thermometer tube. The method of fixing the wire is shown in fig. 2, in which pm and gn are the metallic plates and balls already described, fig. 1; the plates being formed to the curvature of the glass, and firmly cemented to its surface by good sealing-wax. The metallic wire, pn, fig. 1, being first passed through the holes in the brass studs and put gently on the stretch, is secured in place by small plugs of wood, which, pressing the wire against the metal, not only secures it in the hole, but ensures a good metallic contact ; the whole is rendered air-tight by the balls yn, which are flattened and screwed upon studs against the plates, from which they pro- ject, a fine washer of leather being interposed: the small valve v is fixed in the same way. The electrical discharge is caused to traverse the wire pn by means of metallic connexions inserted into holes drilled im the balls pn. 5. Although I found this form of the instrument very sensible and efficient as to its operation, yet it was not sufficiently con- venient in practice. I was hence led to bend the thermometer tube so as to place it in a horizontal position, as shown in figs. 3 and 4, the extremity, , of the tube being either bent downward into the vase containing the coloured liquid, as in fig. 3, or other- wise bent upward and expanded into a small ball open to the * Letter to Vice-Admiral Sir T. B. Martin, K.C.B., Comptroller of Her Majesty’s Navy, &e. Nicol and Co., London, 1823. Electrical Discharge. 343 external air, as in fig. 4; and as the whole was sustained upon a horizontal plane of wood, having free motion upon a similar plane beneath, either extremity of the instrument could be ele- vated within certain limits, so as to give the tube of the ther- mometer a greater or less degree of inclination. This is, in fact, the form of my instrument resorted to by M. Riess, and figured by M. De la Rive in his recent work, Traité de [ Electricité, vol. ii. p. 156; as also by M. Pouillet, Hlémens de Physique, who refers the instrument to M. Knockenhauer. In the course of my experiments with this form of the instru- ment, I sometimes employed long and delicate tubes containing a very small line of coloured fluid, moveable within them as an index merely. I also occasionally used a small column of mercury in the same way. After all my efforts, however, to perfect the instru- ment, I found no form so really efficient and simple as that of the instrument shown infig.5. In this figure, pvnd is the ther- mometer ball as before, capped and screwed at d upon a reser- voir of coloured fluid, dc, and from which the thermometer tube is extended. The tube cad is twice bent, so as to bring it into a vertical position, ad, parallel with the reservoir, cd; the whole is mounted upon a small elliptical base of wood, sustaied on three or four screw feet, as shown in the figure; the vertical portion of the tube, ad, being secured to, and sustained by, a rigid divided scale fixed to a support of wood springing out of the elliptical base. The point o of the level of the liquid in the tube is marked zero on the scale. When an electrical discharge of a given force traverses the wire pn, the fluid is observed to ascend along the scale, indicating the comparative degree of heat excited in the wire. It is to be observed that the diameter of the reservoir, ed, which is a sort of hollow flattened ball, is sufficiently great to render the difference of the level of the fluid in the reservoir, caused by the abstraction of the quantity which ascends in the tube along the scale, infinitely small. _ This form of the instrument is figured in the Transactions of the Royal Society for 1827, in the Memoirs of the Plymouth Institution for 1830, and also in the Transactions of the Royal Society of Edinburgh for 1834*, where it will be found applied {@ the purposes of voltaic electricity. When we employ a long fae wire of platinum in the ball turned into a helix, the instru- ment becomes marvellously sensitive. In order to facilitate ex- periments with different metals, I have sometimes employed a ball pierced in many points of its circumference for the reception of several wires, as shown in fig. 6. I also employed a cylin- drical bulb, shown in fig.7, in which thewires could be either fixed *. Vol: xii: 344. Sir W. Snow Harris on a General Law of one over the other, or otherwise wires of various lengths intro- duced, by fixing them either straight or curved between the two upper holes, or by placing them diagonally between the upper and under holes,—a practice pursued by some of the continental philosophers, and indicated and figured by M. Pouillet in his work, Elémens de Physique. 6. Having thus, for the sake of clearness, described and ex- plained my instrument, such as it was when first invented and afterwards perfected, it may not be unimportant to quote some striking instances of its practical application. It has been well ob- served by the justly celebrated English chemist, Sir H. Davy, that “nothing is more important to the progress of science than the invention and application of a new instrument,” that “ the intel- lectual faculty is not more the source of success in physical dis- covery than the nature of the means which we are led to employ*.” In the first place, however, I may observe that there is really no well-established law of electricity with which the indications of my instrument are not in perfect accordance, the results arrived at by M. Riess not excepted, as I shall presently show. This understood, it is to be further observed, that it was through the agency of this instrument, fig. 5, that Faraday first observed the heating powers of the magneto-electric current during the meet- ing of the British Association at Oxford in 1832+. The heating effect of the shock of the Gymnotus was first observed with this instrument at the Adelaide Gallery in London, in 1839, by Mr. Gassiot and myself. In the course of our experiments we em- ployed a fine silver wire turned into a helix, as first suggested by Mr. Gassiot. Dr. Davy, F.R.S., describes in his most inter- esting work, entitled ‘Physical and Anatomical Researches,’ the great success of my instrument in rendering sensible the heating effects of the shock of the torpedo: he says, “the sen- sibility of this instrument is so great, that the spirit in the stem was not only moved by asingle spark from the electrical machine, but even very distinctly by the electricity of a single voltaic combination composed of copper and zinc wire; the former jth of an inch in diameter, the latter =)th, excited by dilute sul- phuric acid.” This instrument, he further observes, “was strongly affected by active fish, and even distinctly by weak ones ; indeed, occasionally, when it formed part of a circle in ' connexion with the galvanometer, I have seen it affected alone, the galvanometer affording no indication.” Dr. Davy, in his experiments, employed an exceedingly fine wire of platmum, drawn down by Wollaston’s method, described in the Philosophical Transactions for 1813; he employed also a stopcock for regu- * “Elements of Chemistry.” 7 + Faraday’s Experimental Researches, 3rd series, p. 98. Electrical Discharge. 345 lating the altitude of the spirit in the stem, and used as small a quantity of spirit as possible*. Here is, as must be allowed, very strong evidence as to the sensibility of my instrument at least ; and upon the whole I am led to doubt the great superiority and advantage claimed by M. Riess for the particular construction of my instrument which he employed, and which is figured by M. De la Rive in his recent work, vol. ii. p. 156. 7. Having thus explained and illustrated the application and use of the thermo-electrometer, and which was invented full thirty-five years since, I shall endeavour, for the objects of science, to show its exact accordance with the formula of M. Riess when correctly interpreted, as well as its great applicability to the purposes of electrical research. In order, however, to avord any misapprehension, we will revert first, in express terms, to the question we are about to consider. My announcement was, that the heat excited in a metallic wire by the electrical discharge is always the same for the same quantity of electricity, whatever may be the intensity indications of the common electrometers placed in connexion with the battery. M.leProfesseur Riess says, on the other hand, that this announcement is “ untrue,” that he has found the heating effect of the discharge inversely pro- portional to the extent of the battery upon which the electricity is accumulated, that is to say, proportional to the product of the quantity by its “density.” Let us here pause for a ioment to consider what we are really to understand by the term “ density ” of the electricity accumulated in a battery, and which we ima- gine to be measured by the ordinary “ intensity ” electrometerst. 8. If we rigorously examine this very hypothetical question, we shall find that these instruments do not really furnish us with any information whatever relative to “tension” or “ density ” of the accumulated electricity at the instant of discharge; that is to say, at the instant im which the accumulation coming from every point of the coated glass, falls, as it were, in a concentrated form upon the metallic wire, the subject of experiment; neither do étendue, de sorte qu’on peut l’exprimer par la fraction 2. La densité peut s étre déterminée directement au moyen d’un électrométre a poids, 8 c.””—De la Rive, Traité de V Electricité, vol. ii. p- 159. The author gives a figure of the balance-electrometer employed by M. Riess, as figured in his work, Reibungs-elektricitit, vol. i., and by which he infers the density of the charge. Phil. Mag. 8. 4. Vol. 11. No. 73. May 1856. 2A 346 Sir W. Snow Harris on a General Law of they discover to us any specific quality of the electrical agency calculated to modify its effects when discharged under the form of a momentary current. All we learn from these instruments is, the relative state of activity of the whole, or a portion of the charge in a certain direction taken in terms of a given statical force, either attractive or repulsive, and by which we may occa- sionally, and under certain conditions, measure the quantity of electricity accumulated. Now whatever may be the extent of the battery upon which we suppose the charge to be expanded, or whatever may be the distance of discharge as determined by Lane’s discharger, in any case at the moment of discharge, when the statical indications often termed “ intensity ” vanish, and the whole accumulation becomes, as it were, precipitated upon the metallic wire, the force of the momentary current through the circuit is precisely the same, as may be demonstrated by incon- trovertible experiments to be presently referredto. The heating effect, therefore, of the discharge must necessarily be independent of any variable indication of an electrometer attached to the bat- tery, and which may be caused at pleasure to indicate with the same quantity of electricity any “ density” we please. 9. In my paper of 1830, printed in the Transactions of the Plymouth Institution, as well as in my several communications to the Royal Society, I have shown that the electrometer indica- tions are proportional to the square of the charge divided by the square of the surface or extent of coated glass upon which the accumulated electricity becomes expanded, all other things being = If, therefore, the heating effect of the discharge be dependent on the extent of the battery, Q° as insisted on by M. Riess, we should have T= a , and not T= ie unchanged* ; so that we have F= as given in his expression. But both these expressions are evi- dently inapplicable to the heating effect of the discharge, which is altogether independent of 8 or s taken to represent the extent of the battery; nevertheless I do not doubt the truth of the 2 expression T= = when correctly interpreted. I will therefore now endeavour to show in what the difference between my expe- riments and M. Riess’s interpretation of the phenomena consists. 10. It is to be here observed, that when we discharge a given quantity of electricity through a metallic wire, the heating effect will be reciprocally proportional to the resistance in the circuit, that is generally to the extent of the circuit; so that in put- ting C = the extent of the cireuit = the resistance, we have * Phil. Trans. for 1834, p. 221. Electrical Discharge. 347 ] 1 ‘ ; a Go T=-—. Ihave shown, for example, in my communica- Tr tions to the Philosophical Transactions*, that with circuits of cop- per wire varying from 300 to 900 feet in length, arranged in a zig- zag form upon insulating supports, the effect of a given quantity of electricity discharged through the wire of the thermo-electro- meter is inversely proportional to the length of the circuit, the cir- cuit in this case being taken in lengths of 300, 600, and 900 feet, a result which M. Riess has himself confirmed by a subsequent and similar experiment ; hence my expression for the heating effect of 2 the discharge (1) becomes T= —. Now it is important here to Va 9 observe, that this expression T= 2 is virtually the same as M. 2 Riess’s expression T= a the symbol s being, when correctly interpreted, nothing more than the resistance we necessarily in- troduce into the cireuit of discharge, in augmenting the number of charging rods and other obstacles, when we extend our battery by increasing the number of jars; to which we must add the resistance arising from a division of the coated glass upon which the charge is accumulated. In order to make an exact experi- ment, we should accumulate and discharge the same quantity of electricity, either from a given number of jars of different amount of coated surface, or otherwise from a single jar in which the extent of the coating may be varied, or otherwise from coated glass of variable thickness. In either case we may change the indicated * density,” “ déterminée directement au moyen d’un électrométre 4 poids,” without changing the resistance in the circuit. In all these cases, however, although the electrometer greatly varies, the heating effect of the discharge remains the same. If M. De la Rive and M. Riess had resorted to experiments of this kind, they would have found the heating effect quite independent of what they term “ density” of the electricity in the battery as mea- sured by a balance electrometer, or otherwise estimated by the extent of the battery. 11. Take, for example, two jars, A, B, fig. 8, one having about a square foot and a half of coating, the other five or six square feet, charge them with the same quantity of electricity, and then discharge each in succession through the wire of the thermo- electrometer E, taking care to employ in each case the same charging rods and cireuit. The heating effect will be the same, or very nearly so, notwithstanding that the “ density,” as indi- eated by the electrometer, may with the small jar A be sixteen * Trans. Roy. Soc. for 1834, p, 228, 2A2 348 Sir W. Snow Harris on a General Law of times as great as the large jar B, and although the discharge can pass over four times the distance as measured by a Lane’s electrometer. This experiment alone, without other considera- tions, appears to me conclusive of the fact, that the hypothesis of a variable “density” in the accumulated electricity has no substantial foundation, at least so far as it relates to the intensity indications of the electrometer. 12. It is certainly true, as laid down by M. De la Rive in the second volume of his recent work*, and as I long since deter- mined}, that the statical force of a given accumulation will, under all circumstances, be in some inverse proportion to the extent of the coated surface upon which the electricity is accu- mulated ; and this is the case whether the increased surface be derived from several jars, or from single jars of different magni- tudes, although the precise reciprocal proportion of the surface for the latter case may not probably coincide with that of the first. This is, however, a very different affair to that of the effect of the discharge of the accumulated electricity ; and M. De la Rive is certainly inexact when, upon the authority of M. Riess, he confounds the operation of the electrometer with “ density,” and infers that this “density” is in proportion to the number of equal jars of which the battery consistst. We should really be led into serious errors in our analytical expressions if we assumed the existence of any hypothetical quality such as “ density,” as referable to the electrometer, the indications of which vary with the extent of the battery upon far different principles. 13. The whole of this question of “density” or “ tension,” and “intensity,” as it is sometimes denominated, referable to a statical electrometer attached to the battery, is quite explicable upon the principles of electrical induction. The active force of any given quantity of electricity accumulated on an insulated conductor will be always apparently diminished by the influence of a second neutral conductor in a perfectly free state, that is, placed in communication with the ground, or otherwise by the influence of a second insulated conductor charged with an oppo- site electricity. This is really the great secret of the Leyden experiment. In this case the action of the electricity accumu- lated upon the inner coating is, as it were, masked, or rendered more or less latent by the inductive action of the exterior coating in communication with the earth, or by the influence of the op- posite electricity. The force, therefore, in the direction of the electrometer becomes neutralized to a greater or less extent by the influence of the two coatings on each other acting in the direction of the intermediate glass: the indicated intensity will * Volea.ip: log. + Phil. Trans. for 1834. { Traité de Electricité, vol. ii. p. 159. Electrical Discharge. 349 be hence in some inverse ratio of this inductive action. Heres, in a few words, the reason why we find the intensity of a given quantity of electricity accumulated on thick glass so much greater than that of the same quantity accumulated on thin glass; the coatings are, in fact, in the latter case nearer together, and con- sequently the action in the direction of the glass in the latter case greater, The tendency of the accumulation is really to break down the glass intermediate between the two coatings. When, however, the opposite electrical forces operate almost entirely through an external circuit joing the two coatings, all the force in the direction of the intermediate glass vanishes, and the whole accumulation being, as it were, thus set free, discharges through the given circuit. The question of the electrometer indication is purely a question of the development of force in one direction rather than in another, and is certainly no sort of measure of an assumed quality of “ density” in the accumulated electricity. 14. That the heating effect of the discharge is less as we ex- tend our battery by increasing the number of jars, the quantity of electricity bemg the same, is also no doubt true; and if M. De la Rive or M. Riess had met with my paper before quoted (1), and other of my philosophical memoirs, he would have found this question fully investigated, as well as several others of which he has so ably treated. I have shown, for example,— (1.) That the heating effect of the discharge is proportional to the square of the accumulation, all other things being the same*. (2.) That the heating effect is diminished when we accumulate and discharge a given quantity of electricity from a divided surfacet. (3.) That the heat excited in a metallic wire is reciprocally pro- portional to the length of the cireuit of discharge. or resistance, that is to say, to the retardation or duration of the dischargef. (4.) That by the introduction of imperfect conductors into the cirenit, such as water contained in tubes of glass, the heating effect becomes extremely small §. 2 The expression T= aah putting r= the retardation, and which 2 is really nothing more than the expression T= = of M. Riess, has been therefore derived as well from my original investiga- tions, as from the more recent researches of Professor Riess, quoted by M. De la Rive. * Trans. of the Plym. Inst. 1830, pp. 68, 84. + Ibid. + Phil. Trans. for 1534. § Ibid. p. 227, 228. See also Trans. Roy. Soc. Edinb. vol. Xi, 350 Sir W. Snow Harris on a General Law of (5.) I have shown, that, under certain conditions, the best con- ductor may become the most heated, because it can transmit a greater quantity of electricity *. 15. In the Philosophical Transactions for 1827 will be found an experimental investigation of the relative conducting powers of different metals. The results are in accordance with the best general deductions of both the old and modern electricians, di- stinguished by their inquiries in this department of physics. It will be seen in this paper last referred to, that the heating effect of the electrical discharge on a metallic wire of a given diameter is precisely the same as that upon four wires of half the diameter and of equal length; that is to say, in elongating the wire to four times its length by the ordimary mechanical means, and placing it in the ball of the thermometer under the form of four small wires. Now in this experiment we may perceive, that since the dia- meter of each of the smaller wires is one-half the diameter of the large wire, and that each of the smaller wires, in transmitting one-fourth part of the charge, contributes one fourth-part of the total effect, it follows, that if the whole charge were transmitted by one of the smaller wires singly, the heating effect on that wire would become sixteen times as great, since it would transmit four times the quantity of electricity, the heating effect bemg as the square of the quantity (14). Let, for example, the total effect upon the larger wire, or upon the four smaller wires, be 16 degrees of the thermometer scale. In this case we have 4 degrees for each of the small wires considered alone. Now in discharging all the electricity through one of these small wires, we should have a heating effect equal to 64°; that isto say, four - times the effect on the original or large wire. The comparative heating effects, therefore, on these two wires are in the inverse ratio of 1 : 4, whilst their respective diameters are directly as ] : 2. The heating effects, therefore, are reciprocally proportional to the squares of their diameters or to the squares of thei radii, that is, inversely as the area of the section. Here is again another result of the practical application of my instrument such as I constructed it, quite in accordance with well-known laws of con- duction since determined, as also in all the subsequent researches of M. Riess. 16. I might quote many other examples, all confirming the accuracy of my instrument as an instrument of quantitative elec- trical research, such as I constructed it, and its singular opera- tion in producing results which are now received as general laws of electricity. How then can it be said, with any degree of just- ice, as announced by M. De la Rive on the authority of M. Riess, * Edinb. Phil. Trans. vol. xu. Electrical Discharge. 351 that the construction of my instrument is imperfect*, and “ that is the reason why my experiments have been unfruitful,” more especially when we see that almost every experimental deduction arrived at by M. Riess, by means of what he considers a better construction, is in perfect accordance with results I had already obtained. I trust I have clearly shown (10) that the solitary 2 exception taken by M. Riess in his expression Tat is, after all, no exception at all; the expression being, in fact, no other than 2 my own formula Tz = previously deduced, since the symbols s and r may be taken to represent the same thing, viz. resistance to discharge. 17. Since the difference in question bears upon a large and important class of physical researches, I am unwilling to leave the subject without some few additional observations. My first experiments, given in the volume of the Plymouth Institution before mentioned (1), contain illustrations of the diminished heating effect of a given quantity of electricity when accumulated on, and discharged from, many jars—the only point, in fact, upon which M. Riess founds his objection to my instrument in the way I constructed it. It will be found at page 16 of this paper, that the quantity of electricity was measured in precisely the same way as that subsequently adopted by M. Riess, many years after, that is, by the explosions of a Lane’s jar m commu- nication with the insulated negative side of the battery, although M. Riess, full seven years after (Poggendorff’s Annalen, vol. xl. p- 324), claims for himself the especial merit of having first applied this practically. If M. Riess, however, will favour me by a perusal of my memoir above referred to (1), he will find the whole arrangement exactly as he describes it, fully detailed and figured, p. 63, fig. 16, printed in 1830. The method, how- ever, which I finally adopted to measure the quantity of elec- tricity in the battery, as being the most accurate and convenient, was the interposition of a small Leyden phial between the con- ductor of the machine and the battery, and which I have termed a “unit jar” or measure. It is fully described in the Philoso- phical Transactions for 1834+. The electric jars first subjected to experiment were part of a battery originally constructed by Cuthbertson, each jar being 18 inches high and 4 inches in dia- * “Tt is probably to the imperfection of the one (thermo-electrometer) employed by Mr. Harris that we must attribute the inaccuracy of his con- clusions.” —De la Rive, vol. ii. p. 215. English translation. + Page 217. Nothing can exceed the accuracy of this measure, although M. Riess labours to show the contrary. 352 Sir W. Snow Harris on a General Law of meter, containing about a square foot and a half of coating, as A, fig. 8. 18. The results of a series of experiments with six jars clearly showed that the same quantity of electricity discharged from several jars combined, has not so great a heating effect as when discharged from a single jar, or from a less number; the effect, in fact, continued to diminish in some inverse ratio of the num- ber of jars: this is, in fact, Prof. Riess’s experiment. With a view of ascertaining how far this result depended upon an exten- sion of the battery in coated surface, I proceeded to charge a single large jar, equal in surface to three or more of the first jars taken together, and with the same quantity of electricity as at B, fig. 8. Now in this case the battery was extended, not by a divided, but by a continuous surface. The heating effect was now the same as when the same quantity of electricity was discharged from a single jar, not exposing above one-fourth the surface, as already observed (10), notwithstanding that the relative “ ten- sions” or “ densities ” indicated by the electrometer were nearly as 16:1. The result in question, therefore (17), as shown in the experiment before quoted (11), could not possibly depend upon any hypothetical change in the “density” of the accumu- lated electricity, but must necessarily arise out of some disturb- ing force tending to weaken the power of the current of discharge, which disturbing force could be no other than the resistance in- troduced into the cireuit by the extension of the battery in added jars. It is quite impossible, as already observed (10), to extend our battery in this way without at the same time increasing the resistance to discharge by the added rods requisite to charge and discharge the whole combination. And this resistance is still further increased by the use of small metallic chains, often em- ployed to transmit the electricity to the inner coating. 19. Here it is also most important to observe, that in the ordinary electrical battery there is always some resistance to discharge, arising out of the translation, as it were, of the elec- tricity accumulated on the surface of the glass to the coating, by the conducting power of which the electricity is collected from every point of the glass, and transmitted through the circuit of discharge. Now in the common construction of the electrical jar, the coating is never so closely applied to the glass as to be- come as it were identified with it, and so effect this operation perfectly. In the batteries as constructed by the old electricians, a thin sheet of paper was often interposed between the coating and the glass, with a view of avoiding fracture. In this case the resistance to the free translation of the electricity through the coating is remarkable. In the course of my experiments with the jars of the battery before mentioned (16), I found one of the Electrical Discharge. 353 jars so very different in its action from the others, that I was led to strip off the coating in order to examine the precise condition of the surface beneath. Having done this, I found a thin sheet of paper pasted upon the surface of the glass, which being an imperfect conductor became a source of obstruction in the circuit. When this paper was displaced, and the coating applied imme- diately to the glass, the jar acted in every respect like the others. Every kind of cement, therefore, employed to attach the coating to the glass would cause some resistance to the free translation of the charge, according as it is more or less insulating, or of greater or less thickness ; when consisting of any resinous sub- stance, such as common bees-wax, the increased resistance is very considerable. 20. If we coat a jar with an imperfect conductor, such as water, as in the original experiments of the Germans and Dutch, the resistance to discharge is especially marked. In this case the heating effect of a given quantity of electricity accumulated and discharged from such a jar is almost inappreciable by the thermo-electrometer as commonly employed; so that if the ori- ginal experiment had been perpetuated under the form first given by the Leyden experimentalists, we should have known very little of the heating effects of the ordinary electrical battery on me- tallic wires. I recently gave a jar 30 inches high and 10 inches in diameter, a coating of 5 square feet of water, the uncoated in- terval being carefully varnished, and charged it with a measured quantity of electricity. The indicated “intensity” or “ density,” according to M. Riess, of the charge, as measured by a statical electrometer, was nearly the same as that of a similar jar coated with metal and charged with the same quantity of electricity. Still the heating effect of the discharge from the water-coating was scarcely appreciable by the thermo-electrometer then em- ployed ; it was certainly not the one-thirtieth part of the effect of the discharge of the same quantity of electricity from the me- tallic coating, although on introducing a tube of water into the circuit, the discharge readily set fire to inflammable matter such as gunpowder. 21. We find therefore always some resistance to discharge, arising out of the necessary construction of the jar itself, a resistance altogether independent of the resistance proper to the extent of the circuit of discharge, and which it is requisite to consider, and add as a constant whenever we desire to calculate the total resistance. If, for example, we would seek to discover the comparative resistance of metallic circuits varying in length, we must add to the resistance of each circuit this constant resistance in the battery itself, more especially if the quantity of electricity be small and the given circuits of small extent. It is 354 Sir W. Snow Harris on a General Law of only when we employ large quantities of electricity and circuits of considerable extent, that we may neglect the battery resistance as being extremely small. It was not until I employed circuits of 300 to 900 feet long (10), and a considerable electrical accu- mulation, that I found the numbers representing the heating effect on the thermo-electrometer in the simple inverse ratio of the length of the circuit, or nearly so. This source of resistance to discharge, therefore, is an element of much importance. It appears however to have escaped M. Riess’s attention altogether. When we take into account these several sources of disturb- ance, we can scarcely hope to find the heating effeet of a given quantity of electricity always reciprocally proportional to the number of jars, or what M. Riess calls the “ extent of the bat- tery,” although the results may approach that ratio. In some instances, if the quantity of electricity be small and the jars of the battery of great capacity, having for example from 4 to 6 square feet of coated glass each, then the comparative resistance introduced into the cireuit of discharge by the addition of other similar jars, becomes of much greater importance ; if, however, we increase the quantity of electricity, the comparative influence of this resistance will be diminished. I found, in accu- mulating a large quantity of electricity upon jars of great capa- city, that the effect was not greatly different while the accumu- lations were effected upon one jar or two; but this result did not obtain with a small charge. 22. The announcement, which I first made in 1830, of the law of electrical discharge, the subject of this paper, must be understood rather in relation to the indications of the ordinary statical electrometers attached to the battery, than in respect of any hypothetical condition of the discharge itself as to “ tension” or “ density,” as announced by M. le Professeur Riess. All I pre- tend to state is, that the heating effect is altogether independent of the extent of surface upon which the electricity is expanded, and of all electrometric indications, all other things bemg the same. 23. With respect to my experiments, they are certainly not open to the criticism with which M. Riess, quoted by M. De la Rive, has regarded them. They were made with great care, and no expense was spared in the construction of the electrical appa- ratus. The electrical machine employed was a most perfect instrument. It had a plate of glass 3 feet in diameter, and was well adjusted in all its parts; the cushions were insulated on each side of the plate, and were joined by an efficient nega- tive conductor. The action of this instrument, when in working condition, was perfectly regular and efficient, and produced a precisely equal quantity of electricity at each turn of the plate. Electrical Discharge. 355 The battery consisted of five jars of similar dimensions, B, fig. 8, each containing 5 square feet of coated glass. When fully charged, it readily melted and fused into balls 15 feet of fine iron wire. The intensity of the accumulation was valued by means of a statical electrometer of great accuracy, the action of which depended on the attractive force directly exerted between two small circular planes, and reducible to a known standard of weight. The platinum wire employed in the thermo-electrometer to measure the heating effect was of sufficient diameter to com- pletely transmit the whole of the charge. I was not ignorant of the precautions necessary to be observed in this respeet (18), and [ have fully considered them im my memoir in the 12th vol. of the Edinburgh Philosophical Transactions. In estimating the quantity of electricity accumulated, I re- sorted to three different methods,—Ist, the revolutions of the plate of the machine as indicated by a divided circle, and an index fixed on the axis of the plate; 2ndly, by insulating the battery in the way already mentioned (17) ; 3rdly, by the “ unit jar,” also before mentioned (18). 24. In reply to the remarks (Poggendorff’s Annalen for 1841, vol. lii. p. 318) that “I have no clear idea of the theory of the instrument I employed,” &c., I have to observe, that I did not think it requisite in these experiments to consider the first tem- perature of the wire, the specific heat of the air in the ball of the thermometer, and other small elements of that kind, so per- fectly calculated by M. Riess in his formula ac Play ee lc T=(5 +4) Oat +5) (aot 1) Any correction which might arise out of such elements in the results of the experiments in the way I conducted them would be extremely small, and much less than the errors of observation inseparable from the experiment itself. Indeed we deceive our- selves greatly in physical inquiries, when we attempt to reach a degree of refinement inconsistent with the kind of experiments in which we are engaged. It often serves only to complicate the calculation, and introduce new sources of error into our ex- perimental deductions. The first terms of M. Riess’s formula, just quoted, could have no relation to my method of manipula- tion. With respect to the last, I have to observe, that if we attentively consider the nature and mode of operation of the in- strument itself, we shall at once perceive that its indications * depend on the momentary expansion of a small cylindrical column of air immediately in contact with, and surrounding the 356 Sir W. Snow Harris on a General Law of fine wire pn, fig. 5, passing through the thermometer-ball; an impulsive movement thus becomes mechanically communicated, as it were, to the general mass, which, pressing by its elasticity on the surface of the fluid in the reservoir beneath, causes the fluid to ascend along the scale of the instrument. The current of discharge in its momentary passage through the wire un- doubtedly excites in it a greater or less degree of heat. Still the effect is very evanescent, and, as it appears to me, there is not the least ground for concluding that the entire mass of the air in the thermometer-ball experiences an elevation of temperature ; to effect this, some short, but still very sensible portion of time would be requisite, but little or no time elapses. No sooner has the electrical discharge passed through the wire, than the wire appears instantly to recover its original temperature. The ther- mometer-fluid, which at the instant rapidly ascends the scale, as rapidly and immediately descends, and not unfrequently sinks below the zero-point from which it started, a phenomenon quite inconsistent with the notion that the temperature of the mass of the au in the ball had been permanently elevated, and which if so elevated would necessarily demand some time to cool down again to its previous pot. How the doctrines of specific heat can be well applied to such an action as this is not by any means clear. Heat is certainly not added to the mass of air in the ball, or even to the wire in the ordinary way. The heat excited in the wire appears to be the result of a momentary mechanical action, just as we render a nail red-hot by a few blows of a hammer; but however this may be, we can scarcely venture, in the present imperfect state of our knowledge of the causes of heat and electricity, to apply abstract theoretical formule to the indications of such an instrument, the precise value of which, as a measure of a certain species of electrical force, we can only arrive at empirically by experiment; and after all we must not take the instrument for more than it is worth. 25. Experimentally, however, we find a marked accordance between the degrees of movement of the fluid along the scale, and well-established laws of electricity. Take, for example, the well-established law expressed in the formula = Q?, anticipated by Cuthbertson, and first verified by myself in 1830 (14), al- though not referred to by M. De la Rive at p. 146, tom. ii. of his recent work: here we observe that if twice the quantity of electricity be accumulated and discharged through the wire, the fluid ascends to four times the height ; three times the quantity causes it to reach nine times the altitude. Then, again, take the relative conducting powers of various metals. If, as is pretty well ascertained, we take the heating effect in the simple — inverse ratio of the conducting power, we find equal wires of Electrical Discharge. 357 different metals introduced into the ball of the thermometer evince heating effects in this same reciprocal proportion. Thus in the ordinary case of the electrical discharge, silver and copper are with a given quantity of electricity the least heated, and lead the most; gold, zinc, platinum, iron, tin, &c. come in due place between these extremes; whilst the degree of effect indicated on the scale taken inversely, approximate very closely to the com- parative values of these relative conducting powers. It is espe- cially remarkable that the conducting powers of copper and lead, as thus determined, have precisely the same relative value as given in the numbers of M. Becquerel*. The numbers for other metals do not differ considerably when we take into the account the great variety of circumstances liable to derange the result. These, and other experimental facts which might be quoted, favour the conclusion, that the simple degree of movement of the fluid in the stem of the instrument, without further correc- tion, is after all the best measure of the force of the current in the wire; it at least furnishes approximations sufficiently near as to leave no doubt on the mind of the laws we seek to discover. All we require, therefore, in the use of this instrument is a care- ful manipulation, and due attention to the dimensions of the wire in the ball, and other conditions of the experiment. Taking these several facts, to which I have called attention, into con- sideration, I am not disposed to allow the justness of M. Riess’s criticisms on my original inquiries, or that the course of experi- ment pursued by Prof. Riess, and to which M. De la Rive devotes so large an amount of considezation, is so perfect as that which he condemns. 26. It is not without regret that I observe M. Riess’s system- atic disparagement of what I have effected at various times in this department of science. Until my several papers first ap- peared, we had really few, if any, available quantitative processes in electricity. In the course of these papers I was the first to point out and furnish practical methods of quantitative measure- ment, and illustrate thereby many important laws of electrical action. Many of these processes have been virtually adopted by others. “ L’électrométre A poids,” figured at p. 160, vol. ii. of M. De la Rive’s work, together with the process he there de- scribes, is really a bad adaptation of my electrical balance described in the Philosophical Transactions for 1834, and it will be found practically inaccurate. The exceptions taken by M. Riess to my several instruments and my methods of research are without any good foundation whatever. In alluding to my “ unit measure,” (Poggendorff’s Annalen, vol. xl. p. 323), M. Riess observes, “ the measure of electricity by the revolutions of the electrical machine * Traité expérimentale, tom. iii. p. 91. 358 Sir W. Snow Harris on a General Law of only furnishes a rough, an inexact measure of the quantity of electricity??/s750% The ‘method employed by Harris i in the Philo- sophical ‘Tr ansactions for 1834 is still worse.” Losing sight of all the novelty and philosophy of my simple and useful little instrument, M. Riess treats it as a mere casual employment of a Lane’s bottle, and then proceeds to apply to it some rather com- monplace and unsound objections. Yet m following out my arrangement of an insulated battery with a Lane’s electrometer jar in connexion with the outer coating (17), M. Riess really com- promises his own principles. If, as he states (Poggendorff’s Annalen, vol. xl. p. 323), “a bottle is more completely char ged when there is no obstruction to the action of the outer coating,” then if my unit jar be inaccurate on this ground, surely the Lane’s bottle dignified in M. De la Rive’s work with the title of “ Bou- teille électrométrique,” directly interposed between the outer coating of the battery and the earth, must be necessarily at least an equal obstruction to the charging of the battery. The fact is, that there is little or no obstruction at all in either case. The unit jar neutralizes at each explosion, and each discharge must correspond to an equal quantity of electricity accumulated in it. This must be so on the principle long since established and admitted by M. Riess himself, viz. that the quantity of elec- tricity accumulated in a jar will be as the distance of the discharge directly, all other things being the same. Now submit the unit jar to this experimental truth. Attach a Lane’s electrometer to a jar exposing about five square feet of coating, or to a battery of smaller jars; set the balls to given measured distances, say to successive distances which are to each other as 1:2. Here it will be found, if the experiment be carefully made, and there is no dissi- pation of the charge, that at twice the distance twice the number of units as measured by the jar will correspond with the great explosion of the large jar. But how could this happen if the quantity represented by twice the number of discharges of the unit measure was not double the quantity represented by the number of explosions or discharges taken as unity? Faraday, one of the best authorities on sah questions, has, upon a full consideration of the subject, acknowledged the accuracy of m views*, So far from this method being open to the doubts which M. Riess has thrown upon it, it will really be found much more accurate than the method of insulating the battery, which is only aclumsy way of effecting the same thing. The large open surface of an insulated battery 1 is always liable to give off elec- tricity in other directions than that of the “ bottle “of measure,” and we are always at the mercy of the insulations. 27. If we turn to Poggendorff’s Annalen, vol. li. for 1841, * Noad, Manual of Electricity, p. 141. Electrical Discharge. 359 p- 315, there we find a somewhat laborious and learned endea- vour by M. Riess to confound my thermo-electrometer, figs. 1, 2, 3, &c., with the old air electrometers of Kinnersley and Bee- caria. My instrument is treated as a mere extension of these instruments. I have merely the “merit” of suggesting the present application of them; but I think anyone who at all dis- passionately considers the nature and construction of my thermo- electrometer, will see that the refined instrument described in the Philosophical Transactions for 1827 is really no copy what- ever of the old air electrometers. I had certainly not the least idea in my mind of such instruments when I contrived it, and which I did to satisfy the Scientific Commission appointed by the Admiralty in 1823 to examine my proposals for giving effectual security to the Royal Navy from lightning. It was important to me at that time that I should exemplify, by original researches, the relative conducting powers of various metals. Men of no less scientific standing than Sir H. Davy and Dr. Wollaston ex- amined my experimental inquiries, and honoured them with their approbation. My instrument was subsequently submitted to the Royal Society by Sir H. Davy without the most distant idea of its beg a mere copy of the old air electrometers by Beccaria and Kinnersley. Fig. 9 represents one of these instruments by Beccaria, from which M. Riess would have it inferred that mine was derived. But whether we take this or the air instrument of Kinnersley, they neither of them were contrived to do more than illustrate the mechanical force of an electrical explosion in a confined space of air, and I cannot. but regard it as a great misapprehension in M. Riess when he identifies my thermo- electrometer with such instruments. Moreover, I cannot admit any common association with M. Riess in the first application of the principle on which my instrument depends, as expressed in the second volume of M. De la Rive’s work, p. 154; and I regard the arrangement figured, p. 156, as nothing more than a similar arrangement of my own, fig. 3 of this paper, which I employed at least fifteen years before M. Riess’s papers appeared in Pog- gendorff’s Annalen. With respect to the accuracy of my re- searches, I am quite prepared to test them by sound philoso- phical evidence. It is always easy for a learned and able writer to deal severely with the researches of others, and undervalue claims to originality in the invention of philosophical instru- ments, more especially when such claims and researches are immediately in his own path: it is a course by no means un- common in the history of physical science; but it is not perhaps so easy to defend such a course, however unpremeditated, upon just, liberal, and enlightened grounds. 28. I am unwilling to conclude these observations without 360 Mr. T. Tate on certain Modifications of the Form of proper acknowledgement of my sense of the value of Professor Riess’s many interesting researches in this branch of physics. It is really with no view to a painful philosophical controversy that I have been led to submit this paper for the consideration of the sci- entific world, but solely with a view to a correct interpretation of very important electrical phenomena and the progress of elec- tricity. I would also, as already observed, desire to obtain some little consideration, in justice to myself, in reply to the rather disparaging criticisms which M. Riess has been led to make on my original researches, and which have been further and recently repeated by M. De la Rive; and I especially invite the attention of those engaged in electrical investigations to my several papers referred to in this memoir. Plymouth, April 5, 1856. XLIV. On certain Modifications of the Form of the new Double- acting Air-pump with a Single Cylinder. By T. Tats, F.R.A.S* HE characteristic feature of the new air-pump, described in the Philosophical Magazine for April 1856, consists in the double piston acting in a single cylinder. For the sake of di- stinction, I shall call this form of the pump No. 1. [have since constructed this pump with different systems of valves, with the view of determining the form which is most eligible for general use. There is a little loss of dynamic effect in working the pump No. 1, from the circumstance that one of the solid pistons forms a vacuum on one end of the cylinder at every stroke ; but this loss of work, or dynamic effect, is considerably less than that which takes place in the common pump. In order to eliminate this defect, I have placed valves in the pistons A and B, lifting towards the corresponding ends of the cylinder. By this arrange- ment the exhaustion is performed with the least possible expen- diture of work or dynamic effect. This form of the pump, for the sake of reference, I shall call No. 2. But this ceconomie construction is attended with a little loss of exhausting power, owing to the greater amount of air which fills the valve spaces. Whilst the exhaustion effected by No. 1 is measured by about two-tenths of an inch of mercury, that of No. 2 is measured by about four-tenths of an inch. Some persons, in my opinion without a sufficient reason, seem to object to the piston passing the exhaustion orifice E. In order to suit the views of such persons, I have construeted an- other form of the pump, which I shall call No. 3, in which the * Communicated by the Author. the new Double-acting Air-pump with a Single Cylinder. 361 valves are constructed after the manner of No. 2, but in which the pistons are placed a little more apart, so that neither of them ever passes the exhaustion orifice E, but at the end of every stroke the interior face of one of the pistons just arrives at the corresponding edge of the exhausting orifice. It is scarcely ne- cessary to observe, that this form of the instrument possesses the same property as that of No. 2 with respect to the ceconomy of dynamic effect ; but it will be seen that its exhausting power 1s the same as that of the common pump. With the view of showing the applicability of the advantages of the double piston acting in a single cylinder to the valve system of the common pump, I have constructed the form, which I shall call No. 4, represented in the annexed cut, where the arrangement of the pistons, A and B, is the same as in No. 3. In this case all the valves lift inwards; the orifice E, at the centre of the cylinder, leads into the atmosphere ; and the pipes C and D lead to the receiver. The exhausting power, as well as the dynamic effect, of this pump is the same as that of an ordinary double-bar- relled pump. At the same time it must be observed, that this form of the double piston acting in the single cylinder, enables us to apply the moving pressure in the most simple manner. I have found the friction of a single piston, 14 inch in dia- meter, to be 24 lbs., and that of the double piston with the stuffing-box of the piston-rod to be 31 lbs. ; with these experi- mental data I have found the work applied to the different pumps necessary to exhaust the air froma receiver containing 108 cubic inches, to be as follows :— The work of No. 1 (requisite to produce the given exhaustion) is nearly one-half that of the common pump. The work of Nos. 2 and 3 is nearly one-third that of the com- mon pump. Taking all circumstances into consideration, I am persuaded, that, for most purposes, the pump with the solid pistons (No. 1) is the most advantageous form of the instrument. The following is an investigation of the formule employed in calculating the work expended in exhausting the receivers of the different pumps. 1. To find the work expended in exhausting the receiver of the common air-pump. Let U,= the work in the uth double stroke; u = the wor expended in overcoming the pressure E of the external air; v= Phil, Mag. 8. 4. Vol. 11. No, 73, May 1856. 2B 362 Mr. T. Tate on certain Modifications of the Form of the work expended in friction, f being the friction on the piston supposed to be one inch in the section ; v= the work performed by the air in the pump upon expanding from the pressure E,_, to E,,; w= the work accumulated in the air in its transfer; then U; Rg gase tay bE 2fb Here u= jo “= 49° %= Zo Ses logs me (25) Blog, for E,, =(—% "E when the re- ; ape® sistances of the valves are neglected ; “1728 Oy" where w is the weight of a cubic foot of atmospheric air, and v the velocity of discharge, the vis viva of the air in passing through the lower valve being neglected ; - @..\"- a+b. 5b wv? ie. MaVr=Bearzp] +2) =a(=65) E log.—— a ay Qy Bk en ~(2,) bing 22 re: 19 nb(E + 2f) — b ‘Hy 1 ray | log,—— + 14g 2g . And when a is very great, we find the work expended in exhaust- ing ve receiver heres a+b nb ot 2. To find the work eoatili in exhausting the receiver of the pump No, 1. In this case we have for the work of the nth single stroke, U, Sut uy t+ug+ uz. Here u= 2 a'B, where a! is the volume of the air in the barrel when its pressure becomes EH, but a! = aoe ; b a ve 1 =iglags) Bs ump fs Sept tt a ‘te a a+ a= 754 ie aes jg "16 (5) EK log, —— a! = ee a SS) a Sp LTRS, 2g. 1728.29 Naud) >. n eag 1 wv? a \n=1 - ShaaUa= Sha gal (E+ Gay By) (aa) 2 b + (n—1) ) Blog, “*" 44]; ‘ (1) the new Double-acting Air-pump with a Single Cylinder. 363 and when n is taken very great, we find the work expended in exhausting the receiver =ate (1 ub eh 1 a 4{e 14Z log. tan: e +7578» (8) It will be observed, that the work in passing the exhausting orifice has been neglected i in this investigation. 3. To find the work expended in exhausting the receiver of the pump No. 3, and also No. 2 very nearly. In this case we have for the work of the nth single stroke, U,=ut+u, tutu. Here u, u,, and uw; have the same values as in the preceding case, and E E,- Ug = e* alk log. —— Hy * a Ey-1 be; == i 12 ee ale a+6,~ ( a yn a+b. = 73 a(t)" ny ora Ve a . wer? ab, a+b Ds ite *. Bn=1Un= Zn awl {Et +i 29 Fs age a laces tae DE(4 )" Tog. “+ 4.4]. And when a is very great, we find the work expended in ex- hausting the receiver = (b+ 144" oe) + apM romans MAD exactly expresses the least possible work requi- ow at o)E ae) =. site for completely exhausting the space a+6 of air, and the other parts of the expression give the work of resistances essen- tially connected with all air-pump pistons ; hence it follows, that with this construction of pump, the exhaustion is performed with the least possible expenditure of work. Let a=108, 6=12, E=15, = 086, v= 100, f=24+3=1} for the single piston, and 384+3=21 for the double piston, and n=60; then by formule (2), i>) and (4), we find the work in each case as follows, viz. 950, 440, and 300. Hounslow, April 18, 1856. 2B2 [ 364 ] XLV. On the Solution of certain Differential Equations. By Bunsamin Wiiutamson, Fellow of Trinity College, Dublin*. q “ A General Method in Analysis,” published in the Trans- actions of the Royal Society for the year 1844, Professor Boole proposes a method for the reduction of differential equa- tions to others already soluble, and gives several examples of its application. The object of the present paper is to exhibit some of Professor Boole’s results in another form, to apply the same method to another class of differential equations, and to extend such solu- tions to certain analogous partial differential equations. In doing so, I will restrict myself to the consideration of the dif- ferent classes of equations which depend for their solution on (D2+a2)y=0. I. I will commence with the consideration of the equation (p> "Dp +0) y=0, where D stands for 2 This equation is at once transformed into eB (2D. (eD—2n+1) + aa? )y=0. Assume, in accordance with Dr. Boole’s method, y=(xD—1).(#D—8) .... (cD —2n—1)y/; then, since ‘a*(a@D—1).....(vD —2n—1)y'=(#D —8) ... (2D —2n+1)2*y/, the proposed equation becomes (xD—8) ....(eD—2n—1)(2D . zD—1 . +022%)y'=0, or (D?+)". cos(az' a) | c= 62 een alae WG) [ since (04 —m) =0"(a<) : a |. Ez. 2. Let (p:— n.n+1 +0°)y=0. x? * Communicated by the Author. On the Solution of certain Differential Equations. 365 This equation is equivalent to ((«D +n)(@D—n+1)+ aa? )y =e or (« D (@D — 2n+41)+ ax? )a"y — Consequently its solution is by the last d n y=Aann( 5 a) EOS (axe. See Fe (2) Ex. 3. (D? < Sa 1) D +0°)y=0, or («D (« D + 2n+1)+a°a*)y=0; or, as it can be otherwise written, (2D (cD —2n+1)+ ee je y=0. Accordingly the solution is n yadaroet, (5 -') .cos(aw+a). . . (8) Ex. 4. If we had substituted for y, fv.u instead of z”u in Ez. 2, the equation would have taken the form (D3fe— EAIG *—«?) v)u=0, a? or aot pl 2 oe atl *) nS (p gk D+ = 2 +a? ju=0, its solution beg pole ® te -1)'c0 (ax +2) (4) = ae ia” aC cc) er ae ee If we make Le wo, or fe =e”, this equation is immediately seen to be identical with that treated by Dr. Hargreave in the Philosophical Transactions for 1848, and since discussed by Mr. A. H. Curtis in the Cambridge and Dublin Mathematical Journal for the year 1854. II. In any equation if z be changed into ., the operation of becomes —2<; and accordingly, if the solution of any equa- tion of the form ¢(2D)y=x be known, we can immediately de- termine that of the analogous equation ¢(—aD)y=y'. I will illustrate the use of this method of transformation by the solu- tion of a few well-known equations, and then proceed to apply it to the differential equations analogous to those I have already solved. 366 Mr. B. Williamson on the Solution of 2 a? 2 — — = (p ie Pig ayy °, a (ap . (zD +1) +5)y=0: let z= = then the transformed equation is d ~ d 2 2) = (3 (:@-1)+¢#) y= .. the solution is y=Acos (az +a) =A cos (4 +2). » iE) Ex. 2. a? : (De+ y= a (2D. (@D-1)+ “)y=0. The transformed equation is or (25 . (-2 “ 1) +02*)y=0, The solution of this is immediately seen to be y=Az™! cos (az+a). Consequently the solution of the proposed is y=Azcos (4 +2). i ac 8 oe mean Ex. 3. (D pe 2p 4%)y=0. This equation, when transformed, becomes (D2 ase D.+ cst)y= 0; accordingly the solution of the proposed equation is, by (3), d n a ) — 2n+1 -1 = y=Azr (Sa ) cos(4 4a 3 Ez, 4. Again, let 2 This is immediately baw into i equation already dis- cussed in (1); accordingly it has for its solution y=A(La~) "cos (4 +4). stitt.o6) (8) certain Differential Equations. 867 Ez. 5. n.n+1 a? (p>— ah Seay ae “)y=0. This, when reduced, becomes (p-+2p,— n. ut +0) y=0, and consequently its solution by aid of (2) is easily seen to be d ¥ e ) — a+1f 7-1 i y= Ax (fa cos ae : Ez. 6, The more general equation Nan 2 (p+ 4 ae ee — ttt + S)y=0 a? a has for its ae by sat y= AT (0!) 00s (2 42). » + «+. (10) In general, if we make e=2", the operation of is equiva- lent to == and accordingly ¢(#D) is transformed into o(= a) This transformation leads immediately to the soluble forms of Ricati’s equation ; for writing it in its transformed shape, viz. (D?—ctw-*)y=0, or (2D ; (aD —1) —c?a*-))y=0 ; if we assume z!-\=z, this equation becomes (2..(@.-)=(5)'4)0-0 It is readily seen, that, in order that this equation should admit of a finite solution, we must have x =2r+1, when 7 is any j pa positive or negative whole number. Making this substitution, we get (2D ; (eD—2r+1)—a**)y=0, where a= (2r+1)c; the solution of which equation we have already seen to be (1), y= (¢ ot). (Ae + Ale~"), oF ue vis oh aS =(£--)' [a. gertlen* +! | 4, erie bent T), (11) 368 Mr. B. Williamson on the Solution of | which contains the complete solution whenever \ is of the form 2r . 2r+1 | eo . For the practical application of the foregoing solutions, it is 3 only requisite to investigate the expansion of the symbol of ope- : n ration {— a) : da It is readily seen that we may assume this expansion to be of the form (Da-!)”=a-"D" + A,a-"'D"" 4 B,a-" 2D"? + &e. ab Pag: where A,,, B, are constants depending on 7, the forms of which we have to determine. If we operate on both sides of this equation with (= a) , it becomes (Da-1)"*? =a" 1D"*" + (A,— n+ 1)a-”*2D" + (B, — (n+2)A, Jam" aD" + &e. —(2n+1)P,a-2"71; but (Da-!)"*! a7" 1D" *" 4 An. 0-7 2D" + By 077 2D" + Be. Accordingly, equating the coefficients of like powers of D, we get A,—(n+1)=An4+1 B,—(n+2)A,=Bas, &e. hence we conclude that A _ _n.(n+1) Bow (n—1)n. (n+1)(n+2) ea fa ya ae 2.4 ; OS (ey) oes (hae ron 2.4.6 and the complete expansion of (Da~')” is a-pr— at) q-"*1—)"7} ae (n— 1) 23 (n h 2) anFayy-2_ &e. 2 2.4 +1.3... (2n—1)a-2"-(D—a-), There is no difficulty in proving that this expansion holds for negative as well as for positive values of n; and hence by merely changing the sign of , we might have inferred the solution of (3) from that of (1). If we change the sign of a? and expand the operating symbol certain Differential Equations. 369 in equation (1), we immediately obtain the solution already given by Dr. Hargreave : legis _m.m+l (m— 1)m(m+2) ) yaw (2 vse Se A aes 1 ia m.(m+1) (m—1)... (m+2) ) igo (1+ Sapa Cea aT Sood Equations of the form (op? 20 +02) =0 are easily reducible to the proposed form (D?+a*)y=0; for if we assume fz= X?, then this equation becomes (X*D?+ XX'D + a?)y=0, ((XD)?+@)y=0; PT or Be et hence if z= vd = the equation is reduced to the required form, (@+e)r=0 or Ez. 1. ((c?—2*)D?—2D +a°)y=0. Here ee ae Soe= Va. noes gp? y=Acos(asin~® +a). Puss ye 5 (RS) Ez. 2. ((1+2?)D?+aD +a? )y=0. In this case =f Fas Bois aT, and accordingly we get ~ y=A(at+ V1 42%)4 4-14 Act A 14a%)-24=1, (14) Ez. 3. Again, let it be proposed to integrate (D?— cot zD + asin*z)y=0. In this case z=fsin zdz=— COs x, and consequently we have for the solution y=Acos(acosz+a). . » + w « (15) III. If we assume v=/, y=/v, then it can be readily shown 370 Mr. B, Williamson on the Solution of : d d... : d that the operation wT +97, is transformed into ta and ac- cordingly the solution of all partial differential equations of the form $(zD, +yD,)z=V is immediately reducible to that of the differential equation o(t S)eav . More generally, if we make f=, y=’, then the operation avD, +4yD, is transformed into ¢D,; Ac- cordingly we can solve all partial differential equations of the form ¢ . (azD,, + byD,)2= V whenever the solution of the corre- sponding equation ¢ i) a=V! is known. In order to exem- plify the advantage of this method of solving such classes of partial equations, I will apply it to a few examples. Ez. 1. ra? + Wsxy + ty? + a*uz=0, where u,= af 4, it is immediately seen that d d d d ) 2 p= os Eas 8 coe ru? + 2sxy + ty =(27, +15) (os. +97, bye. Accordingly the proposed equation is transformed into d (,4 28 ) = the solution of which is z= . cos at Vfo-+wpav.sinat V fo, or z=,“ cos a Vig +%py 4 sina V the va 9, ae ALO) Ex. 2. rx? + Qsay + ty? + a?u_.z=0, where u_=2-2f e , The solution of this equation evidently depends on that of 2 2 ((4) + “L"),,=0, and accordingly is by (6), exay “cosa Via +ampy=sin aV ua of) SEU Ez. 3. rau? + 2sxy + ty? —2n( px + qy) + a?ugz=0. The solution of this equation is immediately seen from (1) to be o— e a)’ [Leos a Vig +o" sin 4 Vi |. (18) certain Differential Equations. 371 Ex. 4. ra® + Qsay + ty? + (a’u,—n.n+1)z=0, Its solution from (2) is evidently : d n a : ne, sao-( a) [ vr Leos aV Us +po% sin a Vig |: (19) Ex. 5, rx? + Qsay + ty? + (@u_»—n.n+1)z=0. “The solution is, by (9), d : — ; Sis gaan a) [wt cos a Vu_s+ Wo # sin aV Us |. (20) Ex. 6. ra? + 2say + ty? + 2(n+1)( paetqy)+au_.z=0. The solution of this equation depends on that of (8), consequently we have 2=(£o)'[ yt . COS a Vina + po sin a Vin |. (21) tia. 7 ra? + any + ty?+(2 +1)(po+qy) +@u_»2=0. The equation evidently depends for its solution on the differen- tial equation * (o*+2D2+ G + L)a"""D - )y=0; 2 the solution of which, by (12), is py ad y= Ac, cos( a 2 +2). Accordingly the proposed partial differential equation has for its solution z=p4 cos Vin +o esin Af eid traces (22) 2 Ex. 8. p 4 2(n+1) a? - i=. This equation is obtained from (8) by substituting estes for a in the corresponding differential equation, consequently its solution is gee fs o~) [(y+ “)+F,(y—4) | stahs a (20) It is unnecessary to add any further examples of this method, as the foregoing are sufficient to show its application. Most of the partial differential equations hitherto treated by the caleulus of operations are readily seen to be simple cases of this method of reduction by transformation. Trinity College, Dublin, March 5, 1856. f “sve 4 XLVI. Chemical Notices from Foreign Journals. By E. Arxinson, Ph.D. {Continued from p. 204.] N the November Number of the Annales de Chimie, M. Baum- hauer proposes a method for the determination of oxygen in organic substances. The principle on which it rests consists in burning the substance with oxide of copper, and estimating the oxygen lost by the oxide; the quantity of oxygen contained in the carbonic acid and water produced, less the quantity lost by the oxide of copper, gives the amount of oxygen contained in the substance. This determination requires special apparatus, which the author describes. By the continued action of nitric acid on naphthaline, Laurent obtained phthalic acid, whichhas the formulaC* H°O8, Its forma- tion from naphthaline, C*° H$, is explained on the supposition that 4.equivs. of carbonand2equivs. of hydrogen are eliminated as oxalic acid. M. Dusart has found that nitronaphthaline, C?°(NO*)H’, undergoes a similar change when acted upon, under certain con- ditions, by caustic potash. In this case the nitronaphthaline loses 4 equivs. of carbon, which appear to be eliminated as such, and a body C!® H* NO* is produced. This represents the nitro- compound of a hydrocarbon as yet unknown, C!® H®, and which is isomeric with cimnamene. By acting on this new compound, which Dusart names nitrophthaline, with sulphide of ammonium, a base is formed which has the formula C!©H9N. He calls it phthalidine, and describes many of its salts, as well as a substitu- tion product obtained by acting on it with iodide of zthyle. By a secondary action of potash on nitrophthaline a bibasic acid is produced, with the further study of which Dusart is engaged. The same author gives a new method for the formation of the gas propylene. ‘This consists in distilling together a mixture of an alkaline acetate and oxalate. The acetone from the destruct- ive distillation of the acetate, coming in contact with the carbonic oxide proceeding from the decomposition of the oxalate, is de- oxidized, and a gas absorbable by bromine is produced, which is propylene,— C® H® 0? + 2CO=2C0?-+ C8 H¢. Acetone. Propylene. By distilling the bromide of propylene, C® H° Br, which the author prepared from this gas, with sulphocyanide of potassium, he obtained artificial oil of mustard. M. Pelouze has in the same Number a short memoir on the saponification of the oils under the influence of the substances which accompany them in the seeds. Berthelot on Melitose, Eucalyne, and Pinite. 373 The fatty matters contained in the seeds are neutral. When the seeds and various oleaginous kernel fruits are reduced to a state of minute division, by which the cells are destroyed, and the substances composing them put in intimate contact, the neutral fatty matters contaimed in them are changed into a fatty acid and glycerine. In this case a similar change is effected to that ob- served when the cells of the apple or grape, which isolate the ferment, are destroyed by being crushed ; the sugar contained in them, acted upon by the ferment set free, is split up into alcohol and carbonic acid. M. Pelouze ascertained by direct experiments, that the fatty matters, as originally contained in the seeds, are neutral, there being only traces of fatty acids present. His mode of experimenting was to enclose seeds and grains of many different kinds in vessels which effectually excluded the air. From time to time he opened these, and determined the amount of fatty acid liberated. He found that the quantity varied directly as the time. The different kinds of neutral fatty oils varied very much in the rapidity with which they were decom- posed; and this decomposition differs not only with the tempe- rature, but with the quantities operated upon. He attempted, but without success, to isolate the ferment, by which he supposes that the decomposition is effected. In the course of his investi- gations he found that the sugar contained in nuts, almonds, &c., is identical with cane-sugar. In the Australian Manna (which exudes from a species of Eucalyptus) Berthelot has found a crystalline saccharine matter which he names Melitose. The crystallized preparation has the formula C4 H?4O*+4HO, and when dried at 100° C. it loses the 4equivs. of water. Its aqueous solution deviates to the right the plane of polarization ; by the addition of sulphuric acid this power is diminished by about one-third. Its behaviour with reagents is almost exactly that of cane-sugar. But when caused to ferment, by the addition of yeast, it ex- hibits a striking peculiarity. While 100 parts of grape-sugar give, on fermentation, 22-2 parts of carbonic acid, the same quantity of melitose, which is isomeric with it, gives 445 parts. When melitose was treated with SO%, an uncrystallizable saccharine matter was produced. This comports itself exactly as melitose, and produces, like it, on fermentation, exactly half the quantity of carbonic acid which an equal weight of grape- sugar would produce. On examining the solutions of melitose after fermentation, they were found to contain a peculiar saccharine principle which Berthelot has named eucalyne: its quantity was found equal to half that of the melitose employed. It deviates the plane of 874 Mz. de Saint Giles on Hydrated Sesquiowide of Iron. polarization to the right; it has the formula of grape-sugar, is unfermentescible, and agrees in most of its properties with sorbine. The formation of ewcalyne may be thus expressed :— C* H** 04% =4C0? + 2C? H® 0? 4 C!? H!? Ol, Rice peed Melitose. Eucalyne. Melitose appears, then, to be formed of two isomeric compounds, of which one is fermentescible. The action of yeast disunites them, destroying the one without attacking the other. M. Berthelot points out, from the similarity in the properties of this body to cane-sugar, the probability that this analogy ex- tends to the constitution of cane-sugar. This, he observes, has been rendered probable by the researches of M. Dubrunfaut. M. Berthelot has ascertained the existence, in the Pinus Lam- bertianus, of a crystallizable saccharine principle, Pinite, which is isomeric with quercite, and hence differs from mannite by the elements of water. From its reactions it may be ranged along with this class of substances. It forms with stearic and benzoic acids peculiar compounds, with the study of which the author is engaged. By heating the hydrated sesquioxide of iron, Fe? O?(HO)'*, to 100° C. it loses one-third of the water. M. de Saint Giles finds that if this heating be prolonged some time, the change does not merely consist in a loss of water, but that the properties of the hydrate are considerably modified. Its colour is changed, it resembles the calcined oxide in appearance, and it has lost to a great extent its basic properties. It is much less easily soluble in acids, and does not produce prussian blue with ferro- cyanide of potassium. It no longer exhibits the phenomena of incandescence on being heated to a dull redness, which is cha- racteristic of the non-modified hydrate. He has also found that acetate of peroxide of iron undergoes, when heated, a similar change. Instead of water, acetic acid is liberated. The natural ferric hydrates are divided into two classes, which correspond with these two states. Those of the first species are crystalline, and have the colour of the calcined or of the modified hydrate. They contain 10 per cent. of water, which corresponds to Fe?0®, HO. The second species contains the amorphous hydrates: they have a yellowish-ochreous colour, and their for- mula is Fe? 0?(HO)", agreeing with the non-modified hydrate. M. de Saint Giles thinks that in the modified hydrate a true allotropic transformation has been effected, and he points out that the changes which Crum has observed in the acetate of alu- mina are perfectly analogous. He has confirmed the observa- tions of Crum, and has also found that the hydrate of alumina is modified by heating in a similar manner. Bineau on the Absorption of Ammonia by Cryptogamic Plants. 375 M. Bineau has made some observations on the absorption of ammonia and the nitrates by cryptogamic plants. His experi- ments were made on the Hydrodictyon pentagonale and the Con- ferva vulgaris. He infers from them these consequences :—1. The demonstration of the fact of an absorption or of a decomposition of ammoniacal salts with an intensity analogous to that of CO”. This has hitherto had no parallel in the case of saline matters, which are generally absorbed much less abundantly than their solvents. 2. That the nutrition of the Algz is promoted by their tendency to remove the nitrates from the waters in which they vegetate, either by directly assimilating the nitrogen, or by con- verting the nitrates into ammoniacal salts. 3. That the elabo- ration by green plants of nitrogen compounds, as well as of car- bonic acid, is facilitated by light. In the November Number of Liebig’s Annalen, Dr.Casselmann discusses at some length the process proposed by Streng for volu- metric determinations by means of bichromate of potash. He communicates the results of some comparative experiments which he made with a view of testing this method, and describes the conditions under which it is applicable. He considers that the method has only a limited application for scientific purposes. M. Toel describes the formation of cystine in the urine of two females who suffered under an inflammation of the kidneys. The late Dr. Pauli discovered in wood-vinegar an acid which he thought to be pyrogallic acid; since his death the question has been examined by M. Buchner, who finds that it is not py- rogallic acid, but oxyphenic acid, C!? H®O*. This acid invari- ably accompanies the products of the destructive distillation of wood, but is not found in coal-tar, being probably decomposed by the presence of ammonia. M. Kerl proposed a method for the determination of copper, which consisted in precipitating it from its solution by means of metallic iron. The metallic copper which precipitates is then dried and weighed. M. Mohr proposes to substitute zine for iron in this process, and gives the analytical results of determi- nations made in this way, which were very accurate. The copper salt or mineral is dissolved in hydrochloric acid. If nitric acid be present, it must be removed, either by lengthened boiling of the strong hydrochloric solution, or by adding a little sulphate of iron. Distilled zinc is then added. When the copper is en- tirely precipitated, which is ascertained by testing a drop of the solution with sulphuretted hydrogen, and the whole of the zinc dissolved, the copper is washed, dried, and weighed in a crucible. 376 Dr. Neubauer on Catechu and its Acids. It was found by Fischer that nitrite of potash mixed with solu- tions of cobalt gave a crystalline yellowish precipitate. This body has been examined by Stromeyer, and he considers it to be composed according to the formula Co? 0? 2NO® + 3KO NO®+ 2HO. It is formed when a neutral cobalt salt is mixed with nitrite of potash, oxygen being absorbed, thus :— 2Co O, SO? + 5(KO NO®) + 0 +2HO=Co? 0%, 2NO8 +3(KO NO%) +2HO +2(KO SO%). This reaction is of great use in detecting cobalt, as many special experiments sufficiently prove. Stromeyer gives a method for the preparation of nitrite of potash, which consists in fusing salt- petre with lead in the proportion of 1 to 2; but it seems to pos- sess no great advantages over the ordinary methods. Prof. Schmid of Jena communicates that he has detected urea in diabetic urine. Dr. Vohl of Bonn gives the results of experiments made with the view of employing hyposulphite of soda as a precipitant for the heavy metallic oxides ; but they do not show that this body has any decided superiority over the reagents at present in use. In the December Number of the same journal, M. von Bibra, in a communication “On Hair and the substance of Horn,” states that he has not succeeded in extracting any colourmg matter from these substances; and thinks that the colours, especially of the various kinds of hair, depend on the structure, and that this is a question for the microscope. He also adduces a large number of determinations of the sulphur, fatty matter, and inorganic constituents contained in these substances. From these it is impossible to draw any useful general conclusion. Dr. Neubauer furnishes the results of an investigation “On Catechu and its Acids,” which he undertook in the hope of find- ing a similar connexion between catechuic acid and catechutannic acid to that which Strecker found to exist between gallic acid and tannic acid. He had hoped that by treating this acid with sulphuric acid it would split up into catechuic acid and sugar ; but neither catechuic nor catechutannic acid afforded any sugar when thus treated. He notices that the various kinds of catechu arise from the different modes of preparation, and that. the catechuic acid con- tained in them all is of the same composition, C!”7 H!? 0". In this Number of the Annalen is given an abstract of the results which Piria has obtained in his investigation of Populine. M. Piria on Populine. 377 Its formula is C49 H®? O!* + 4HO, and it loses the water at 100° C. It is to be considered as composed of benzoic acid, saligenine, and grape-sugar :— Co H2 0% 4 4HO =C™ Hé 04+ C4 Ht 04+4C!? H!?? O!2, Benzoic acid. Saligenine. Grape-sugar. Populine. Salicine is composed of saligenine and grape-sugar, and when treated with acid is resolved into saliretine and grape-sugar. Simi- larly, populine, when treated with acid, splits up into benzoic acid, saliretine, and grape-sugar. It was thought that if the benzoic acid could be separated from the populine, salicine would be formed. By the action of caustic baryta this is effected, and the salicine separated has also the physical and chemical properties of that prepared in the usual way. The benzoic acid formed corresponds with the quantity required by theory. By treating salicine with nitric acid, helicine is produced. In the same way, by treating populine with nitric acid, benzo-helicine isformed. And from this benzo-helicine, by the action of caustic magnesia, helicine is produced, which is exactly the same as that produced directly from salicine. Helicine is decomposed by acids into grape-sugar and hydride of salicyle ; and benzo-helicine similarly into benzoic acid, hydride of salicyle, and grape-sugar. Piria considers at length the conditions under which bodies form copulated compounds. When these copulated compounds split wp, the elements of water are always assimilated, and in the formation of these copulated compounds water is eliminated. He proposes this law, that when n constituents unite to form a copulated compound, 2(ua—1) equivalents of water are eliminated. Thus in the copulation of two bodies =2, of 3=4, of 4=6, of 5=8. Piria considers populine an example of the copulation of three bodies, and here 4: equivs. of water are separated. Amyg- daline is considered by Piria as containing five groups of atoms, in the copulation of which 8 equivs. HO are separated. By acting on glycerine with iodide of phosphorus, Berthelot obtained a new body, the iodide of propylenyle, C°H°®I. The discovery of this body has lately led to numerous important results. It occupies the same place in a new series of alcohols as iodide of zthyle does in the common alcohol series. By distilling it with sulphocyanide of potassium, Berthelot and De Luca, and independently of them, Zinin, obtained the artificial oil of mus- tard, C? N S*K + C® H®I=C* H°C?N S*. By acting with it on acetate and benzoate of silver, Zin has obtamed compounds Phil. Mag. 8. 4. Vol. 11. No. 73. May 1856. 2C 378 Mr. A. Cayley on a Result of Elimination. which correspond to acetic and benzoic ethers. Thus, Co HAT \AeO; 4H? 0?) = Agt Iodide of propylenyle. Acetate of silver. Iodide of silver. +C®°H°O, C*H? 0%, and C®H*I Acetate of propylenyle. Iodide of propylenyle. AsO 0" HO = “Agi” + ~C°H®O; C’ Ee: Benzoate of silver. Iodide of silver. Benzoate of propylenyle. Zinin has also obtained a carbonate of propylenyle correspond- ing to carbonic ether. When mercury is acted upon by iodide of propylenyle, a metallo-organie compound is formed, which cor- responds to that obtained by Frankland as the result of a similar reaction with iodide of zthyle. XLVII. Note upon a Result of Elimination. By A. Cayiny, Esq.* [T the quadratic function (4, b, ¢,f, 9, ha, y, 2)? break up into factors, then representing one of these factors by Ex+ny+z, and taking any arbitrary quantities a, 8, y, the factor in question, and therefore the quadratic function is reduced to zero by substituting B—an, yE—al, an—BE in the place of 25-4, 2, Write (4, b,c, Lg AY RE— an, yE—al, an —B¢)° = (a, b,e,f, g) h\{a,8,7)*; the coefficients of the function on the right hand are a= en? | + be? 2 fb ic b= c& . +a€ . —9SE c= b&+a7? ‘ . —2hEn f= jE . —anb+hcé +98 Ba ROP sin Ne Oe en h= . ~ AS +9nb+fCE —c&n. And it is to be remarked that we have identically a&+hn+go=0 hé+byn+ff=0 gs&+fn+ef=0. Hence of the six equations, a=0, b=0, c=0, f=0, g=0, h=0, any three (except a=0, h=0, g=0, or h=0; b=0,7=0; ‘or g=0, f=0, c=0) imply the remaining three. * Communicated by the Author. Prof. Thomson on the Dynamical Theory of Heat. 379 If from the six equations we eliminate £&, 7?, &e., we obtain o= > ie i ear ee alae . | =0 Ge ee OL ) 2g, : Gta a; f —2h aks —4, h, I —% Sf —b, de —h, 4g, Cc, —e And the equation Q =0 is therefore the result of the elimi- nation of £, n, £ from any three (other than the excepted com- binations) of the six equations. But from what precedes, it appears that the equation O =O must be satisfied when the qua- dratic function breaks up into factors, and consequently O must contain as a factor the discriminant ee i lpg | h, b, f 9 f e of the quadratic function. This agrees perfectly with the results obtained long ago by Prof. Sylvester in his paper, “ Examples of the Dialytic Method of Elimimation as applied to Ternary Systems of Equations,” Camb. Math. Journ. vol. 11. p. 232; but accord- ing to the assumption there made, the value of O would be (to a numerical factor prés) abecK. The correct value is by actual development shown to be O=—2K*. It would be interesting to show @ priori that 0 contains K? as a factor. 2 Stone Buildings, March 28, 1856. XLVIII. On the Dynamical Theory of Heat.—Part VI. Thermo- electric Currents. By Witt1amM Tuomson, M.A., Professor of Natural Philosophy in the University of Glasgow. [Continued from p. 297.] §§ 141-146. Elementary Explanations in Electro-cinematics and Electro-mechanics. 141. W HEN we confined our attention to electric currents flowing along linear conductors, it was only necessary to consider in each case the whole strength of the current, and the longitudinal electromotive force in any part of the circuit, without taking into account any of the transverse dimensions of the con- ducting channel. In what follows, it will be frequently necessary to consider distributions of currents in various directions through solid conductors, and it is therefore convenient at present to notice 2C2 380 Prof. Thomson on the Dynamical Theory of Heat. some elementary properties, and to define various terms, adapted for specifications of systems of electric currents and electromotive forces distributed in any manner whatever throughout a solid. 142. It is to be remarked, in the first place, that any portion of a solid traversed by current electricity may be divided, by tubular surfaces coinciding with lines of electric motion, to an infinite number of channels or conducting ares, each containing an independent linear current. The strength of a linear current being, as before, defined to denote the quantity of electricity flowing across any section in the unit of time, we may now define the intensity of the current at any point of a conductor as the strength of a linear current of infinitely small transverse dimen- sions through this point, divided by the area of a normal section of its channel. The elementary proposition of the composition of motions, common to the cinematics of ordinary fluids and of electricity, shows that the superposition of two systems of cur- rents in a body gives a resultant system, of which the intensity and direction at any point are represented by the diagonal of a parallelogram described upon lines representing the intensity and direction of the component systems respectively. Hence we may define the components, along three lines at right angles to one another, of the intensity of electric current through any point of a body, as the products of the intensity of the current at that point into the cosines of the inclination of its direction to those three lines respectively ; and we may regard the specification of a distribution of currents through a body as complete, when the components parallel to three fixed rectangular axes of reference of the intensity of the current at every point are given. 143. The term electromotive force has been applied in what precedes, consistently with the ordinary usage, to the whole force urging electricity through a linear conducting arc. When a cur- rent is sustained through a conducting arc by energy proceeding from sources belonging entirely to the remainder of the circuit, the electromotive force may be considered as applied from with- out to its extremities ; and in all such cases it may be measured —electrostatically, by determining in any way the difference of potential between two conducting bodies insulated from one another and put in metallic communication with the extremities of the conducting are ;—or electro-dynamically, by applying to these points the extremities of another lmear conductor of infi- nitely greater resistance (practically, for instance, a long fine wire used as a galvanometer coil), and determining the strength of the current which branches into it when it is so applied. These tests may of course be regarded as giving either the amount of the electromotive force with which the remainder of the circuit acts on, or the whole of the electromotive force efficient in, the - Prof, Thomson on the Dynamical Theory of Heat. 381 passive conducting are first considered. On the other hand, the electromotive force acting in the portion from which the energy proceeds is not itself determined by such tests, but is equal to the whole electromotive force of the sources contained in it, di- minished by the reaction of the force which is measured in the manner just explained. The same tests applied to any two points whatever of a complete conducting circuit, however the sources of energy are distributed through it, show simply the electromotive force acting and reacting between the two parts into which the circuit might be separated by breaking it at these points. In some cases, fer instance some cases of thermo-electric action which we shall have to consider*, these tests would give a zero indication to whatever two points of a circuit through which a current is actually passing they are applied, and would there- fore show that there is no electric action and reaction between different parts of the circuit, but that each part contains intrin- sically the electromotive force required to sustain the current through it at the existing rate. An actual test of the electromo- tive force of sources contained in any part of a linear conductor is defined, with especial reference to the circumstances of thermo- electricity, in the following statement :— 144, Def. The actual intrinsic electromotive force of any part of a lmear conducting circuit is the difference of potential which it produces in two insulated conductors of a standard metal at one temperature, when its extremities are connected with them by conducting ares of the same metal, and insulated from the remainder of the circuit. The electromotive force so defined may be determined, either by determining by some electrostatical method the difference of potentials in the two conductors of standard metal mentioned in the definition, or by measuring the strength of the current pro- duced in a conducting are of the standard metal of infinitely greater resistance than the given conducting arc, applied to con- nect its extremities when insulated from the remainder of its own circuit. 145. With reference to the distribution of electromotive force through a solid, the following definitions are laid down :— Def. 1. The intrinsic electromotive force of a linear con- ductor at any point is the actual intrinsic electromotive force in an infinitely small are through this point divided by its length. Def. 2. The efficient electromotive force at any point of a linear conducting circuit is the sum of the actual intrinsic elec- tromotive force in an infinitely small arc, and the electromotive force produced by the remainder of the circuit on its extremities, divided by its length. * For one of these see § 167 below. 382 Prof. Thomson on the Dynamical Theory of Heat. Def. 3. The intrinsic electromotive force in any direction, at any point in a solid, is the electromotive force that would be experienced by an infinitely thin conducting are of standard metal, applied with its extremities to two points in a line with this direction, in an infinitely small portion insulated all round from the rest of the solid, divided by the distance between these points. Def. 4. The electromotive force efficient at any point of a solid, in any direction, is the difference of the electromotive forces that would be experienced by an infinitely thin conducting are of standard metal, with its extremities applied to two points infinitely near one another in this direction, divided by the distance between the points, in the two cases separately of the solid being left unchanged, and of an infinitely small portion of it containing these points being insulated from the remainder. 146. Principle of the superposition of thermo-electrie action. It may be assumed as an axiom, that each of any number of co- existing systems of electric currents produces the same reversible thermal effect in any locality as if it existed alone. §$ 147-155. On Thermo-electric Currents in Linear Conductors of Crystalline Substance. 147. The general characteristic of crystalline matter is, that physical agencies, having particular directions in the space through which they act, and depending on particular qualities of the substance occupying that space, take place with different intensities in different directions if the substance be crystalline. Substances not naturally crystallme may have the crystalline characteristic induced in them by the action of some directional agency, such as mechanical strain or magnetization, and may be said to be inductively crystalline. Or again, minute fragments of non-crystalline substances may be put together so as to con- stitute solids, which on a large scale possess the general charac- teristic of homogeneous crystalline substances ; and such bodies may be said to possess the crystalline characteristic by structure, or to be structurally crystalline. 148. As regards thermo-electric currents, the characteristic of crystalline substance must be, that bars cut from it in different directions would, when treated thermo-electrically as linear con- ductors, be found in different positions in the thermo-electrie series; or that two bars cut from different directions in the sub- stance would be thermo-electrically related to one another like different metals. This property has been experimentally demon- strated by Svanberg for crystals of bismuth and antimony; and there can be no doubt but that other natural metallic crystals will be found to possess it. I have myself observed, that the Prof. Thomson on the Dynamical Theory of Heat. 383 thermo-electric properties of copper and iron wires are affected by alternate tension and relaxation in such a manner as to leave no doubt but that a mass of either metal, when compressed or extended in one direction, possesses different thermo-electric rela- tions in different directions. Fragments of different metals may be put together so as to form solids, possessing by structure the thermo-electric characteristic of a crystal, in an infinite variety of ways. Thus, a structure consisting of thin layers alternately of two different metals, possesses obviously the thermo-electric qualities of a crystal with an axis of symmetry. I have investi- gated the thermo-electric properties in all directions of such a structure in terms of the conducting powers for heat and elec- tricity, and the thermo-electric powers, of the two metals of which it is composed; and bars made up of alternate layers of copper and iron, one with the layers perpendicular, another with the layers oblique, and a third with the layers parallel to the length, illustrating the theoretical results which were communi- eated along with this paper, were exhibited to the Royal Society. The principal advantage of considering metallic structures with reference to the theory of thermo-electricity is, as will be seen below, that we are so enabled to demonstrate the possibility of ery- stalline thermo-electric qualities of the most general conceivable type, and are shown how to construct solids (whether or not natural crystals may be ever found) actually possessing them. 149. The following two propositions with reference to thermo- electric effects in a particular case of crystalline matter are pre- mised to the unrestricted treatment of the subject, because they will serve to guide us as to the nature of the agencies for which the general mathematical expressions are to be investigated. Prop. I. If a bar of crystalline substance, possessing an axis of thermo-electric symmetry, has its length oblique to this axis, a current of electricity sustained in it longitudinally will cause evolution of heat at one side and absorption of heat at the oppo- site side, all along the bar, when the whole substance is kept at one temperature. Prop. Il. If the two sides of such a bar be kept at different temperatures, and a homogeneous conducting are be applied to points of the ends which are at the same temperature, a current will be produced along the bar, and through the are completing the circuit. 150. For proving these propositions, it will be convenient to investigate fully the thermo-electric agency experienced by a bar cut obliquely from a crystalline substance possessing an axis of symmetry, when placed longitudinally in a cireuit of which the remainder is composed of the standard metal, and kept with either its sides or its ends unequally heated. Let @ and 384. Prof. Thomson on the Dynamical Theory of Heat. denote the thermo-electric powers of two bars cut from the given substance in directions parallel and perpendicular to its axis of symmetry respectively. Let us suppose the actual bar to be of rectangular section, with two of its opposite sides perpendicular to the plane of its length and the axis of symmetry of its sub- stance. Let a longitudinal section in this plane be represented by the accompanying diagram ; let OA or any line parallel to it be the direction of the axis of symmetry through any point ; and let denote the inclination of this line to the length of the bar. Let the breadth of the two opposite sides of the bar perpendicular to the plane of the diagram be denoted by a, and in the plane of the diagram 6. The area of the transverse section of the bar will be ab; and therefore if y denote the strength, and 7 the in- tensity, of the current in it, we have (§ 14:2) ix ab 151. We may suppose the current, itself parallel to the length of the bar, and in the direction from left to right of the diagram, to be resolved (§ 142) at any point P at the side of the bar into two components in directions parallel and perpendicular to OA, of which the intensities will be icos and isin @ respectively. The former of these components may be supposed to belong to a system of currents crossing the bar in lines parallel to OA, and passing out of it across the side CD into a conductor of the standard metal; and the latter, to a system of currents entering the bar across CD from the same conductor of standard metal, and crossing it in lines perpendicular to OA. The resultant current in the supposed standard metal beside the bar will clearly be parallel to the length, and can therefore (this metal being non-crystalline) produce no effect influencing the thermal agency at the side of the bar or within it. The inclinations of the cur- rents to a perpendicular to the separating plane of the two metals Prof. Thomson on the Dynamical Theory of Heat. 385 being respectively 90°—w and a, their strengths per unit of area of this plane, obtained by multiplying their intensities by the cosine of those angles respectively, will be each equal to ZcOS@sSIN@. Hence the absorptions of heat which they will produce at the sur- face of separation of the metals per unit of area per second will be : ! | ae , — ri cos @ sin wf8, and 7 icos@sin ath, respectively. According to the general principle of the super- position of thermo-electric actions stated above, the sum of these is the rate of absorption of heat per unit of surface when the two systems of currents coexist. But the resultant of these systems is simply the given longitudinal current in the bar, with no flow either out of it or into it across any of its sides. Hence a simple current of intensity i, parallel to the sides of the bar, causes absorption of heat at the side CD amounting to F icos w sin wt(d—8), per unit of area per second; and the same demonstration shows that an equal amount of evolution must be produced at the oppo- site side C’D'. These effects take place quite independently of the matter round the bar, since the metal carrying electric currents which we supposed to exist at the sides of the bar in the course of the demonstration, can exercise no influence on the phe- nomena. 152. If J denotes the length of the bar, the area of each of the sides perpendicular to the plane of the diagram will be 7a; and therefore the absorption over the whole of the side CD, and the evolution over the whole of the other side C'D’, per second, will be a ila cos w sin wt(p—8), r +7708 sin at(p—8). It is obvious that there can be neither evolution nor absorption of heat at the two other sides. 153. An investigation similar to that which has just been completed, shows that if the actual current enter from a con- ductor of the standard metal at one end of the bar, and leave it by a conductor of the same metal at its other end, the absorption and evolution of heat at these ends respectively will amount to ; (40 cos? w + tp sin? w) per second. 386 Prof. Thomson on the Dynamical Theory of Heat. 154, Let us now suppose the two sides CD, C’D! to be kept at uniform temperatures, T, T’, and the two ends to be kept with equal and similar distributions of temperatures, whether a cur- rent is crossing them or not. Then if a current of strength y be sent through the bar from left to right of the diagram, in a circuit of which the remainder is the standard metal, there will be reversible thermal action, consisting of the following parts, each stated per unit of time. (1.) Absorption amounting to (T) - y, ima locality at the temperature T. (2.) Evolution amounting to (T’) iy in a locality at the temperature T’. (3.) Absorption amounting to Ivy at one end (that beyond CC’), and (4.) Evolution amounting to Ily at the other end ; where, for brevity, Q(T) and Q(T’) are assumed to denote the values of + (f— 9) sin@wcosw at the temperatures T and T’; and IT the mean value of + (0 cos? w+ ¢ sin?w) for either end of the bar. The contributions towards the sums appearing in the general thermo-dynamic equations which are due to these items of thermal agency are as follows :— [om —Q(T! vie Y towards >H,, OD) OP 47 H Bee = oy towards ae the thermal agencies at the ends disappearing from each sum in consequence of their being mutually equal and opposite, and similarly distributed through localities equally heated. Now when every reversible thermal effect is included, the value and of S— must be zero, according to the second general law. Q(T) _ a(t") T dis reversible thermal agency not yet taken into account. But pro- Q(T) act’) bably = a temperature, for natural crystals; and it certainly does vary with the temperature for metallic combinations structurally crystalline (for instance, for a bar cut obliquely from a solid consisting of must vanish, or there must be a Hence either may not vanish, that is © may vary with the Prof. Thomson on the Dynamical Theory of Heat. 387 alternate layers of copper and iron, the value of QO decreases to zero as the temperature is raised from an ordinary atmospheric temperature up to about 280°, and has a contrary sign for higher temperatures). Hence in general there must be another rever- sible thermal agency, besides the agencies at the ends and at the sides of the bar which we have investigated. This agency must be in the interior; and since the substance is homogeneous, and uniformly affected by the current, the new agency must be uni- formly distributed through the length, as different points of the same cross section can only differ in virtue of their different cir- cumstances as to temperature. If there were no variation of temperature, there could be no such effect anywhere in the inte- rior of the bar; and therefore if d¢ denote the variation of tem- perature in an infinitely small space dx across the bar in the plane of the diagram, and y an unknown element, constant or a function of the temperature, depending on the nature of the sub- stance, we may assume = dt 'X ae as the amount of absorption, per unit of the volume of the bar, due to a current of intensity 7, by means of the new agency. The whole amount in a lamina of thickness dz, length /, and breadth a perpendicular to the plane of the diagram, is therefore ay = aldx, or l As there cannot possibly be any other reversible thermal agency to be taken into account, we may now assume SH $4 (01) —2(0)] +" ya} . (22), Hy 2 FQ) air’) x \ Bye oe mit( tah . @3). H The second general law, showing that = a must vanish, gives by the second of these equations, Q(T) _ A(T’) a: AEN Substituting in place of T, ¢, and differentiating with reference to this variable, we have as an equivalent equation, dh +{ Xdt=0 .. . (24). Ry t t=. Ee as ota ee es 388 M. R. Clausius on the Discovery of and using this in (22), we have if toa =H.=y 3 in dt ° . e e ° . (26). This expresses the full amount of heat taken in through the agency of the current y, of which the mechanical equivalent is therefore the work done by the current. Hence (according to principles fully explained above, §§ 109, 110) the thermal cir- cumstances must actually cause an electromotive force F, of which the amount is given by the equation 1(TOQ Bee Pes = are St eee (27), to act along the bar from left to right of the diagram; which will produce a current unless balanced by an equal and contrary reaction. This result both establishes Proposition II., enunciated above in § 149, and shows the amount of the electromotive force producing the stated effect in terms of T and T’, the tempera- tures of the two sides of the bar, the obliquity of the bar to the crystalline axis of symmetry, and the thermo-electric properties of the substance; since if @ and ¢ denote its thermo-electric powers along the axis of symmetry, and along lines perpendicular to this axis, at the temperature ¢, and @ the inclination of this axis to the length of the bar when the substance is at the tem- perature ¢, we have N= + ($-6)sinocos . . . . (28). . 155. By an investigation exactly similar to that of § 115, which had reference to non-crystalline lmear conductors, we deduce the following expression for the electromotive force, when the ends of the bar are kept at temperatures T, T’ from the ter- minal thermal agency I, of a current investigated in § 153 :— Ti pas (ita aaa fray eae =z (Gcosto+psin%) . . . . (80). [To be continued. | where XLIX. On the Discovery of the true form of Carnot’s Function. By hi. Cravsivs. To the Editors of the Philosophical Magazine and Journal. GENTLEMEN, , 1 Fe a paper communicated to the Royal Society of Edinburgh in 1851*, Prof. W. Thomson ascribed to Mr. J. P. Joule the discovery of the theorem, that Carnot’s function, which Cla- * Edinb. Trans. vol. xx.; and Phil. Mag. 4th series, vol. ix. the true form of Carnot’s Function. 389 peyron expressed by C, and Thomson by the fraction 2 “is nothing more than the absolute temperature multiplied by the equivalent of heat for the unit of work.” I have hitherto avoided mentioning this pomt in my papers; principally because I have so high an esteem for the labours of the physicist for whom Prof. Thomson claims priority, that I was anxious to avoid even the ap- pearance of wishing to lessen his deserts. But as Prof. Thomson has since then frequently repeated that assertion,—among other places in the paper in the March Number of this Journal, where, in page 215, he calls that theorem “ Mr. Joule’s conjecture,”-— I think it necessary to say a few words on the subject. Holtzmann established the same formula for the function C in a paper which appeared as early as 1845*; and Helmholtz, in his pamphlet published in 1847, “On the Conservation of Force,” citing Holtzmann’s paper, calculated several values obtained by this formula, and compared them with those arrived at by Cla- peyron ina different manner. But the views upon which Holtz- mann founded his speculations do not agree with the mechanical theory of heat as at present received ; so that after this had been recognized, the correctness of the formula found by him was, naturally, again rendered doubtful. On this account, in a paper communicated to the Berlm Academy in February 1850+, “On the Moving Force of Heat,” in which I brought Carnot’s pro- position in agreement with the mechanical theory of heat, I again endeavoured to determine his function more accurately. Therein J arrived at the same formula as Holtzmann, and I believe that I then, for the first time, correctly explained the principles upon which this formula is based. In presence of these facts, Prof. Thomson, to justify his state- ment, sayst, “It was suggested to me by Mr. Joule, in a letter dated December 9, 1848, that the true value of w might be in- versely as the temperature from zero.” Against this I must beg to urge,—First, that, as far as I am aware, it is usual, in deter- mining questions of priority in scientific matters, only to admit such statements as have been published. And I believe that this custom ought to be conscientiously adhered to, especially in theoretical investigations ; for it usually requires continued and laborious research in order to give to a thought, after it has been first entertained, and perhaps casually communicated to a friend, that degree of certainty which is necessary before venturing upon its publication. Secondly, that since Thomson does not say that * On the Heat and Elasticity of Gases and Vapours. By C. Holtzmann. Mannheim, 1845. + Poggendorff’s Annalen, vol. Ixxix.; and Phil. Mag. 4th series, vol. ii. { Edinburgh Transactions, vol, xx. p. 279. 390 Royal Society :— Mr. Joule had proved the theorem, but only that he had offered it as an opinion, I do not see why this opinion should have the priority over that which Holtzmann had arrived at three years before. In conclusion allow me to make one remark. Ina more recent paper, “Ona Modified Form of the Second principal Theorem in the Mechanical Theory of Heat*,” I have introduced, instead of Carnot’s function C, another function of the temperature, which I have designated by T, and by which all developments are very much simplified. This function has a determinate relation to that of Carnot’s, which I have expressed by the equation av dt A TC in which ¢ represents the temperature, and A the equivalent of heat for unit of work. It is easily recognized, that, according to this equation, the functions © and T are in general to be con- sidered different; but that for the special case, in which C is proportional to the absolute temperature, T must be also pro- portional to it. And in fact I have shown, from the same prin- ciples which before led me to the determination of C, that in all probability T is simply the absolute temperature itself. I remain, Gentlemen, With great respect, yours &c., Zurich, March 20, 1856. R. Craustius. L. Proceedings of Learned Societies. ROYAL SOCIETY. {Continued from p. 306. ] December 6, 1855.—Sir Benjamin Brodie, Bart., V.P., in the Chair. fi ee following communication was read :— “(On Chemical Affinity, and the Solubility of the Sulphate of Baryta in Acid Liquors.” By F. Crace Calvert, Esq. Solubility of the Sulphate of Baryta. The author observes that sulphate of baryta is not an insoluble salt, as is generally admitted, for he has found that 1000 grs. of nitric acid, of spec. grav. 1°167, are capable of dissolving 2 grs. of sulphate of baryta; and what renders the knowledge of this fact still more useful in analytical chemistry is, that the insolubility of this salt is affected even by the weakest nitric or hydrochloric acids; for whilst 0-062 gr. of sulphate of baryta only requires 1000 grs. of nitric acid, of spec. grav. 1°032, to hold it in solution, the same quantity of salt requires 50°000 grs. of pure distilled water to dissolve it. * Pogeendorff’s Annalen, vol. xciii. Mr. C. Calvert on the Solubility of Sulphate of Baryta. 391 What is not less useful to know is, that the solubility of sulphate of baryta is affected in a higher degree by the bulk of the acid than by its strength. The two following tables, taken from amongst many others contained in the paper, will not only illustrate his fact, but will also give an insight into the way in which the experiments were conducted. ‘The first table illustrates the influence which in- creasing bulks of the same nitric acid exert on the formation of sul- phate of baryta, and the second table the action which increasing strengths of acid have :— TasLeE XVI. Number of/Number Sul- | Nitrate of Timers divisions | of divi-| Spec. |phate of} baryta ae 3 al Quantity Garni Order ofthe sions of} grav. | potash | poured in, Aes oe of sulphate Gant aoe of |alkalimeterthealka-| of the | dis- | previously a te t 4 of baryta f ad 7 jars. of nitric | limeter | bulk of | solved | dissolved | “P to precipi- ae Pie A acid, spec.|ofwater| acid. | in the | in 20 grs, aneenr tated. F grav. 1°167.| added. acid. | of water. | “PPC 1 20 20 | 1:167| 3:34 | 5°00 |3min.| 4:28 | Average 2 20 40 | 1:120) ... Rae Joe 4:34 | quantity 3 20 60 | 1085; ... mer ies dissolved 4 20 80 | 1:067| ... 5 ar equal 5 20 100 | 1:057) ... os wed 4:35 | 0-10gr. 6 20 120 | 1050}... bes wes 4°35 7 20 140 | 1044] ... 555 eae 4:36 8 20 160 | 1039] ... est 9 20 180 | 1035]... “3 Aye 10 20 200 | 1:032| ... 350 ses 4:38 Taste II. Number of|Corresponding|Quantity|Quantity| Weight of |,.. . uantit: Order aijuions eore of ‘ a FT ae ni- ‘ malphuts pee paren See ae of jars. |of the alka-| nitric acid, |phate of | trate of of PREet P ee of baryta limeter. | sp. gr. 1'167.| potash. | baryta.} baryta. 0 appear.| dissolved. 1 40 466°8 | 3°34 | 5-00 | 4:46 | Instantly 0-02 2 80 933°6 aed wee Ee 20 minutes} 1°29 3 120 1400°4 eae ake Bae 2 hours 2°34 4 160 1867-2 ss oe Soc 83 hours 3°66 5 200 2334-0 Said nae eee 24 hours 6 240 2800°8 a Fe ned No precip. 7 280 3267-6 os 8 320 3734-4 9 360 4201-2 id Se oa 10 400 4668-0 ase Be ds These tables clearly show the influence which a given strength of nitric acid has on the solubility of the sulphate of baryta; for there is a precipitate in three minutes in all the jars of the first table, whilst we have a precipitate only in the first four jars of Table II. Another fact which is observed in these tables is, that whilst 240 divisions of the alkalimeter of nitric acid, spec. grav. 1°167, are capable of dissolving, or preventing the formation of, 4°46 grs. of sulphate of baryta, 240 divisions of an acid, of spec. grav. 1°032, only retained in solution 0°086 gr. It follows from these facts, that 392 Royal Society. in future the practice of rendering liquors acid with nitric or hydro- chloric acids, must be discontinued when sulphates are to be. deter- mined, or separated from chromates, phosphates, &c. Influence of Mass on Chemical Affinity. The researches of the author, to illustrate the influence which mass exerts on chemical affinity, are extensive ; a few of the results arrived at are here given. The following table will clearly show the marked influence which increasing volumes of nitric acid have in preventing the formation of sulphate of baryta :— Tasie IV. Number of |C ding} Quantit : A ee Sree ce 4 uals bere ee tok ‘Time when precipitate Of jars. demi: sp. ay 67. Sar f of baryta. | of baryta. appeared, 1 40 4668 |5:12grs.| 8:00 7:13 |[nstantly 2 80 933°6 wee wae wa 2 minutes 3 120 1400-4 ve deel cheers Sowa eeeee waeewenee wees eereeees see eeeees So. lewewscece! sen eeeeoe ee eereee seeeeenes £o. Lo. So. Io, ZO. Lo. see eeenee to, ee eewenes to, vo. wl. et wneeee feet e tens seeeereee Pence tees weeteenee TO, /z.0€ bbr.of ZET.O£ £16.62 626.62 £2g.6z $33.62 783.67 649.62 gzg.6z 606.62 Loo,0f br1.08 -Lo.of gbr.0£ 1$0,0f £90.08 9638.62 $36.62 7£6.62 £56.62 VEL.6z 606.62 $9L.6z 0£6.6z $26.62 1$6.6z 646.62 £z0,0£ 060,0£ br1.0f €or.0£ ovr.o£ 336.62 oLo,of $16.62 go00.0£ £96.62 0g0.0£ 60,0 gz1.0£ I£1.0£ ZEZ.O£ L67z.0f Ivf.0£ of7.0£ o$f.0€ 6£1.08 L61.0€ LLt.0f 9gz.0£ SL¥.0& 6£5.0f ofS.0£ LLS.0& 9SS.0f 69S.0£ $gS.0£ 909.0 mt8 5\4 “xUyy “LAST “yore "gg8i “qguoTT jo shed eT eae ae aa fNOLSOg 70 TTROA “AT Ag ‘AUNNUQ BsuvpT younpung yo “UOysNO[D *_ “Ady ay? fg pun $UuopuoryT sau SHOIASIHY yo Ajaro0g younynoys0 fy ay} fo uapsvy ay} yo uosdMOoYy, "IN fig apou suorynasasgg 1n01b0j0.s00;a7r THE LONDON, EDINBURGH ano DUBLIN PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. [FOURTH SERIES.] JUNE 1856. LII. Contributions to the Metallurgy of Copper. By Av Diew*, pe following investigation was made in the metallurgical laboratory of the Museum of Practical Geology, at the request of Dr. Perey, with the special object of ascertaining the causes of the characteristic properties of ordinary “tough pitch copper” and of “ overpoled coppert.” Before detailing the experiments, it may be well to describe very briefly that part of the smelting process termed refining, in which the copper is obtained in these conditions. An impure copper, the product of previous operations, is kept melted in the oxidizing atmosphere of a reverberatory furnace for a consider- able time. The products are copper containing suboxide in solution, and a slag rich in suboxide of copper. The object of this process is to remove as completely as possible by oxidation, the last traces of various metals and the sulphur left in the cop- per after the previous treatment. Copper thus saturated with suboxide is known as dry copper. The slag is then skimmed off, and anthracite thrown upon the surface of the melted copper. By this means the suboxide is reduced, and the action is com- pleted by plunging one end of a pole of green wood under the surface of the melted metal. The gases produced by the decom- position of the wood produce a kind of ebullition, which causes every portion of the metal to be brought more rapidly and thoroughly in contact with the anthracite than would otherwise * Communicated by the Author. + For a detailed description of the refining of copper see Phil. Mag. S. 4. vol. v. p. 406. ° Phil. Mag. 8. 4. Vol. 11. No. 74. June 1856. 2K 410 Mr. A. Dick’s Contributions to the Metallurgy of Copper. be the case. When the copper has attained its maximum tough- ness and malleability, it is laded into ingot moulds, and is known as “tough pitch copper.” If the poling process is continued beyond a certain point, the metal loses much of its toughness and malleability, and is known as “ overpoled copper.” Dry Correr.— Determination of the amount of suboxide. The sample operated upon was made at the Hafod Works, Swansea, in the year 1848, in the presence of Dr. Percy. (a). By heating a known weight of dry copper in hydrogen and weighing the water produced.—Some of the metal cut from the ingot was rolled out as fine as possible and cut into small pieces, of which 13234 grs. were placed in a German glass tube, which was connected with a weighed tube containing chloride of cal- cium. A current of dry hydrogen was then passed through the tubes, and, after complete expulsion of the air, heat was applied to that containing the copper. When the temperature rose to redness, a distinct odour of sulphuretted hydrogen was perceived in the escaping gas, which(anstantly blackened lead paper. This production of sulphuretted hydrogen is curious, because it shows that the coppét'sattrated with suboxide still retams a trace of sulphur in some’ form or other. During the progress of the experiment, a slight metallic sublimate was formed in the cooler part of the tube—but in a part much too hot for arsenic to condense,—which was found to contain lead. The quantity was, however, too small for any very exact experiments to be made upon it. After continuing the experiment for some time, the tube containing chloride of calcium was disconnected, and when cold reweighed. The weight of water was 1:93 gr., which is equivalent to 10°21 per cent. of suboxide in the dry copper. In another experiment, 136°41 grs. of the same dry copper gave 1:82 er. of water, which is equivalent to 9°34 per cent. of sub- oxide. Sulphuretted hydrogen was again observed at the begin- ning of the experiment. It is certain that the hydrogen em- ployed was free from sulphuretted hydrogen and also from water. The difference in the results shows that the method cannot be relied on for accuracy. (b). By melting a known weight of dry copper in hydrogen and estimating the oxygen by loss.—The apparatus employed was a small Stourbridge clay crucible fitted with a perforated lid. It was filled with hydrogen by means of a small porcelain tube which passed through the perforation in its lid, and was heated by charcoal arranged in a convenient furnace. Satisfactory results were not obtained; because, when the dry copper was melted in this way, it was found that great spirtimg occurred, and that the projected globules could not be all collected from Mr. A. Dick’s Contributions to the Metallurgy of Copper. 411 the inside of the lid and crucible for the purpose of being weighed. This took place even when the heat was applied very slowly, and was apparently due to the escape of the water formed by the reduction of the suboxide. (c). As loss by the wet way.—A weighed portion of dry copper was dissolved in nitric acid, and the solution was saturated with caustic potash and boiled. The precipitate was collected on a filter, washed, ignited, and weighed. It was evaporated with nitric acid until its weight was constant. From the oxide ob- tained the metal was calculated, the difference between the weight of which and that of the dry copper was estimated as oxygen. This method will not yield absolutely accurate results, because dry copper is not a mixture of chemically pure copper and sub- oxide, but contains in addition small quantities of lead, antimony, and other metals, which will interfere slightly with the result, owing to the difference in their atomic weights: still the error must be very small. In one experiment, 10°73 grs. of dry cop- per yielded 13:18 grs. of oxide ; in another, 9°17 grs. of dry copper yielded 11°26 grs. of oxide. From the first experiment, the dry copper contained 98°09 per cent. of copper; from the second, it contained 98:01 per cent. The difference estimated as oxygen corresponds to 17-04 per cent. of suboxide of copper by the first experiment, and 17°74 per cent. by the second. Tovex Prrcu Coprer.—In this condition, the metal, like che- mically pure copper in certain states, is possessed of the highest degree of malleability and ductility at all temperatures. It is well known that tough pitch copper cannot be remelted, except under special conditions, without losing in part its malleability, Karsten showed that it contained suboxide of copper, and that this was essential to counteract the injurious effect exerted upon the malleability of the metal by foreign metals. Hence it is easy to conceive why tough pitch copper can scarcely be remelted without losing part of its malleability ; because, if the atmosphere is a reducing one, the suboxide is reduced, and the metal assumes the brittleness of overpoled copper ; or, if it is an oxidizing one, too much suboxide is formed, and the metal assumes the brittle- ness of dry copper. The following experiments were made upon this subject. ‘The tough pitch copper operated upon was either an ingot made at the Hafod Works, Swansea, or else commercial wire or sheet. Tough pitch copper from the ingot, after having been melted in hydrogen, was so brittle that it split at once when hammered at the ordinary temperature, and the brittleness was much greater when the metal was hot. Various samples of wire and sheet, sunilarly treated, were all found more or Jess brittle, especially when hammered hot. Similar samples melted under charcoal 2E2 412 Mr. A. Dick’s Contributions to the Metallurgy of Copper. were similarly altered; and that this was not due to carbon ab- sorbed by the metal and acting injuriously upon its malleability, will be shown fully further on; but it may be here stated, that electrotype copper, which is nearly chemically pure copper—at least that operated upon was,—remained perfectly malleable after having been melted under charcoal*. The charcoal employed in these and all following experiments had been digested im hy- drochloric acid and thoroughly washed with water, to get rid as much as possible of the action of the ash upon the metal in pre- sence of carbon. Demonstration of the presence of suboxide in tough pitch copper. (a). By heating a known weight in hydrogen and weighing the water produced.—The metal was heated to redness in hydrogen, when water was found to be produced. Experiments were then made to determine the proportion of suboxide in the same way as already described (a) in respect to dry copper, and the results obtained were equally discordant and unsatisfactory. Towards the beginning of each experiment a trace of sulphuretted hydrogen was produced, just as when dry copper was similarly operated on; and it was ascertained that tough pitch copper does contain a trace of sulphur, by dissolving it in nitric acid and testing the solution for sulphuric acid. A small metallic sublimate contain- ing lead was formed, as when dry copper was experimented on. The highest amount of suboxide shown by this method was 2°95 per cent. When copper wire or foil was so treated, it was found to un- dergo a curious change. After having been heated in hydrogen, it could not be bent without at once breaking, and it lost its lustrous surface. The pliability of the wire or foil could not be restored by annealing it at a red heat in steam, which was em- ployed because it exerts neither an oxidizing nor a reducing action. The same loss of pliability took place when carbonic oxide or coal-gas was employed instead of hydrogen. It evidently arises from the porosity produced by the reduction of the sub- oxide which the metal contains, and must be distinguished from the brittleness produced by melting the wire or foil in any of these gases. For if the metal be first melted m any of them and then rolled out, which can be done though the metal cracks slightly at the edges, it will be found that the foil so produced is not in the least affected by heating in them; moreover, elec- trotype copper, which contains no suboxide, is not altered by heating in any of them. (b). By melting a known weight of copper wire in hydrogen and estimating the oxygen by loss.—The same spirting took place as * The copper employed was prepared by Messrs. Elkington and Co., Birmingham. Mr. A. Dick’s Contributions to the Metallurgy of Copper. 413 when dry copper was operated upon, though in a less degree, but still sufficient to render the method inaccurate. (c). By melting a known weight of copper wire under charcoal and estimating the oxygen as loss.—Kven when the heat was very slowly applied, the same spirting sometimes took place, in con- sequence of which the charcoal in the crucible, after the experi- ment, was always washed by decantation from any globules which had been projected into it. If these were weighable, they were added to the large button. The loss which the copper under- went by this treatment was estimated as oxygen. That the metal does not take up an amount of carbon sufficient to in- terfere materially with the results, will be shown further on. Two different samples of wire were operated upon in the follow- ing determinations of the amount of suboxide present in them, which for the sake of convenience of reference will be called A and B. A was thicker wire than B. A, 218°24 grs. lost, by melting under charcoal, 0°76 gr., which corresponds to 3:10 per cent. of suboxide. B, 17648 grs. lost, by melting under charcoal, 0°635 er., which corresponds to 3°21 per cent. of suboxide. In another experiment, 200°68 ers. lost 0°765 gr., which corresponds to 3°37 per cent. of suboxide. According to Karsten, the amount of suboxide in tough pitch copper is under 2 per cent. ; but these experiments show that it is present in larger quantity in the specimens met with in England. Although in the preceding calculations the oxygen has always been estimated as present as suboxide, it is not maintained that the whole of it exists in that state in the copper; because com- mercial copper contains small quantities of various metals, gene- rally lead, or antimony, or both, which may occur in it as oxide and not as metal. For this reason the quantity of oxygen found has always been given, as well as the amount of suboxide it corre- sponds to, supposing it to be combined with copper only. In the copper wire previously alluded to as A, 0°17 per cent. of lead was found by dissolving a known weight of it in nitric acid, evaporating the solution to dryness with sulphuric acid, and dis- solving the anhydrous sulphates in water. The sulphate of lead was then collected on a filter, washed with water, and ignited with the usual precautions. This wire contained no anti- mony. Its specific gravity was 8°853. In the sample referred to as B, 0°29 per cent. of lead was found by the same treatment, and 0°31 per cent. of antimony: the antimony was separated from the copper by digesting the mixed sulphides in sulphide of ammonium containing excess of sulphur. The specific gravity of this specimen was 8°733. In a sample of sheet copper, 0:27 per cent. of lead was found, but no antimony. All of these 414 Mr. A. Dick’s Contributions to the Metallurgy of Copper. split at the edges when hammered out at a dull red heat after having been melted under charcoal. They could, however, be hammered out when cold without cracking in the least. The pieces experimented on weighed about 150 or 200 grs. ; possibly larger pieces would be more difficult to hammer out without cracking, but it would require an experienced coppersmith to give an opinion on the working properties of such pieces. Similar pieces as those alluded to cut from the ingot of copper made at the Hafod Works, cracked even when hammered cold after bemg melted in hydrogen or under charcoal. The amount of lead was not determined in this ingot. No complete analyses of copper, such as wire or sheet, were made; and in those published with which the writer is acquainted, no mention is made of oxygen as a constituent: but, what is curious, in some, metals such as potassium, calcium and magnesium are said to occur. This seems to require further investigation. Russian copper com was found to contain oxygen, but it seems to be less essential to the malleability of this variety of copper than to the English copper ; because when the oxide in Russian copper is reduced by melting under charcoal, the metal may be hammered out even at a red heat without cracking much. This seems to show greater purity, though it is not equal to electrotype copper. Several experiments were made with the view of finding some method of melting tough pitch copper without either increasing or diminishing the amount of suboxide present in it, which, if practicable, would allow of its being melted without losing mal- leability. The two substances employed were common salt and chloride of calcium, the former not chemically pure chloride of sodium, but commercial salt. The method pursued was to melt the salt and drop the metal into it. It was found that electro- type copper, melted in this way, could be afterwards hammered out either cold or at a dull red heat without cracking at the edges in the least ; but that ordinary copper wire, after having been so melted, cracked when hammered at a dull red heat. When working with known weights of copper wire, it was found to undergo considerable loss of weight. Thus in one experi- ment the wire B lost, by melting under common salt, 2°44 per cent.; in another it lost 2°05 per cent.; and in another, at a temperature just sufficient to melt it, it lost 1°35 per cent. When the salt in which the metal had been melted was afterwards dis- solved in water, there was left an insoluble substance which was found to contain copper and chlorine, but which was not further examined. The loss of weight was much greater when chloride of calcium was employed, amounting in one case to 7:17 per cent. No similar experiments were made with weighed quan- tities of electrotype copper. Mr. A. Dick’s Contributions to the Metallurgy of Copper. 415 The best method of testing copper for oxygen is to heat a strip of it, about as thick as a sixpenny-piece, in a reducing atmosphere for about half an hour, and then to try if it still retains its pliancy completely, which it will not do if it contained a notable quantity of oxygen. The diminution of specific gravity produced by the porosity arising from the reduction of the oxide will be afterwards alluded to, when treating of the effect of am- monia on red-hot copper. OverroLep Correr.— It is generally believed that the brittle- ness of overpoled copper is due to the presence of carbon. In all the specimens which the writer examined, or made by melt- ing tough pitch copper, or commercial wire or sheet in charcoal, lead or antimony, or both, were found. And it was ascertained by experiment, that the addition of these substances to pure copper in the same amount as they existed in overpoled copper, was sufficient to give to the previously pure copper the brittle- ness of overpoled copper. Various other substances, likely, from the process of manufacture, to occur in overpoled copper, were sought for, and experiments were made to ascertain the effect which they would have by adding them to pure copper. Effect of Nitrogen.—This has been supposed to play a part, and. it seemed likely to do so, because, according to certain state- ments, the presence of a most minute quantity of it in copper renders it extremely brittle (see English edition of ‘Gmelin’s Chemistry,’ vol. v. p. 444), where the compound is described as “nitride of copper with very great excess of copper.” It is said to be made by passing dry ammoniacal gas over red-hot copper wire. According to one statement, the copper increases in weight and diminishes in specific gravity. No such com- pound, however, seems to be formed by this method. Itis true that ammonia, passed over red-hot copper wire, renders it ex- tremely brittle; but this is evidently due to reduction of the suboxide, and not to absorption of nitrogen ; because, if the gas be passed over red-hot copper wire made from electrotype copper, which contains no suboxide, the wire is found to be unaltered. Or if the commercial wire be first melted in hydrogen or under charcoal, so as to reduce the suboxide, then rolled out, and after- wards submitted to the action of ammonia at a red heat, it will be found to remain perfectly unaltered. According to the expe- riments made on this subject by the writer, when the wire lost its phability by the action of ammonia at a red heat, it was always found to have lost weight and diminished in specific gra- vity, and water was produced. When the wire did not lose its pliability, it was found to have remained unaltered in weight and also in specific gravity, and no water was produced. Tough pitch copper, that is, copper containing suboxide, when 416 Mr. A. Dick’s Contributions to the Metallurgy of Copper. submitted to the action of ammonia, or indeed any reducing gas at a red heat, is altered in appearance on the surface, owing to the slight porosity produced. If the surface was previously polished, it becomes dull. If the experiment is continued long” enough to reduce the suboxide in the centre of the piece of metal operated upon, it may afterwards be completely reduced to powder by rubbing it gently in a mortar; but if the action of the gas has not extended to the centre, a core of tough metal remains, from which the altered portion cracks off by bending the piece of metal backwards and forwards. It is curious that the copper containing suboxide is rendered more brittle by ammonia than by any other reducing gas which has been tried; but that the change arises simply from reduction of the suboxide seems proved by the fact, that copper containing no suboxide is not altered by heating in ammonia. No quantitative experiments were made to ascertain exactly whether every trace of suboxide is reduced by heating the wire in ammonia, which seems probable, because the wire, as has been said, is rendered still less pliant than when heated in hydrogen for a similar period. The specific gravity of the wire B was found to have diminished by heating in ammonia from 8°733 to 8°64. Effect of Silicon—Berzelius seems to have been thefirst to show that when a mixture of finely divided copper, silica, and charcoal is strongly heated, a combination of copper and silicon is obtamed (see English edition of ‘Gmelin’s Chemistry,’ vol. v. p. 464). It seemed, therefore, not unlikely that overpoled copper might con- tain some silicon, because carbonaceous and siliceous matters are in contact with it when in the furnace at the overpoled state, and that it might owe some of its properties to the silicon which it contained. It was accordingly sought for by dissolving over- poled copper in nitric acid, evaporating the solution to dryness, and heating the residue till the nitrate of copper was decomposed. The oxide, on being dissolved in hydrochloric acid, left no silica. A few experiments were, however, made to ascertain the proper- ties ‘of the compound more fully than seems to have been done, and to see whether it was fitted for any practical purposes. It resembles bronze in appearance, but has a pink tinge, which bronze has not. It is harder than copper, and, at least in cer- tain proportions, tougher than bronze. One specimen, which was found by analysis to contain 1°82 per cent. of silicon, had the specific gravity of 8°70. It could be hammered and rolled out when cold,-but cracked immediately when hammered at a dull red heat. It was hardened by hammering, and softened again by annealing. When “dipped” in nitric acid it became black, but could be dipped so as to retain its original colour by mixing some hydrofluoric acid with the nitricacid, A medallion Mr. A. Dick’s Contributions to the Metallurgy of Copper. 417 of it was cast at Messrs. Robinson and Cotton’s Works, Pimlico. It was said to require a higher temperature for casting than bronze. The surface of the casting was said to be good. No experiments were made to ascertain how much silicon copper may be made to combine with in this way; but in one specimen accidentally prepared, the quantity was very much larger than in that alluded to previously. Effect of Carbon.—This has been supposed to be the cause of the brittleness of overpoled copper. According to Karsten, 0-05 per cent. of carbon is sufficient to cause copper to crack when hammered hot. He adds, moreover, that the presence of carbon increases the influence of small quantities of lead, antimony, and such metals as affect the malleability of copper. A great many experiments were made to ascertain the effect of carbon upon copper. It would be useless to describe all the experiments which were made on this subject ; accordingly those only which seem most conclusive will be alluded to. It is of course essential that both the copper and the carbon should be as pure as possible. In examining the result of an experiment made some years ago by Dr. Percy, the necessity of this was brought prominently forward. A quantity of finely divided cop- per (“best selected,” from Messrs. Newton, Keats and Co.) had been diffused through charcoal powder, and heated strongly for some hours for the purpose of ascertaining the effect of carbon on copper. The shots of metal were afterwards melted together under charcoal. It was found that the metal so treated could be rolled into sheet or drawn into wire when cold, but that it cracked when worked hot. On testing this copper, it was found to contain a very notable quantity of silicon and a small quan- tity of phosphorus and iron. These seem to have been derived chiefly from the charcoal employed. It was found that small pieces of electrotype copper, after having been melted under charcoal—which, as usual, had been digested in hydrochloric acid and washed with water,—could be hammered out without cracking, either when hot or cold. A mixture of rather large pieces of electrotype copper and charcoal powder were heated together for about half an hour at a temperature approaching whiteness. The contents of the cru- cible were then stirred with a piece of wood, so as to cause the metal to sink to the bottom of the pot, after which it was cast into an iron ingot mould to be drawn into wire. The following somewhat similar experiment was made at the same time. Several pieces of electrotype copper were placed in a crucible lined with charcoal powder, which was then completely filled with charcoal anf exposed to a temperature approaching white- ness for about an hour, The furnace containing the crucible 418 Mr. A. Dick’s Contributions to the Metallurgy of Copper. was then allowed to go out gradually, so that the metal had the opportunity of absorbing carbon at all intermediate temperatures in very favourable circumstances, being surrounded on all sides by charcoal. It was remelted under similar conditions, and the lump so obtained was sent, along with the small ingot, to Mr. David Forbes at Birmingham, who was kind enough to get them rolled into sheet and drawn into wire. No mention was made of the object of the experiment, but it was requested that they might be treated like ordinary copper, and that the men super- intending the rolling mill would give an opinion on the working qualities of the metal. When the wire and sheet were returned, it was said, that although the casting was not good, yet the metal was fit for any work. It would seem from these experiments, then, that the amount of carbon in the copper did not render it brittle, and the opportunities afforded to the metal to absorb carbon were far greater than it has during the short period which elapses between the time when the copper is at the tough pitch till that at which it is at the overpoled state in the refining process ; so that it is proved that the brittleness of overpoled copper is not due to carbon. A very marked effect of carbon on an ingot cast in the ordinary manner will be referred to after- wards. Whether the carbon present in overpoled copper increases the injurious effect exerted upon the malleability of the metal by the foreign metals always present, has scarcely been inquired into ; because if tough pitch copper—which, as it contains oxide, cannot contain carbon—be melted in hydrogen, it becomes brittle, just as it does if melted under charcoal; and any difference in the degree of brittleness requires more experience than the writer is possessed of to detect. A great many experiments were made for the purpose of de- termining whether carbon actually is present in copper which has been melted under charcoal. Of these the most conclusive will be given, from which it will be seen that the question is not yet definitely settled. Electrotype copper was melted under charcoal and afterwards rolled out. The sheet, after having been cleaned by nitric acid and boiling in solution of caustic potash, was dissolved in perchloride of iron. The solution was left at rest for a day or two so as to deposit a small quantity of sus- ended matter, which was washed by decantation. When dry, it had a dark bluish-gray colour. It was mixed with a little recently ignited litharge, and the mixture was heated in a small tube. Several small globules of malleable metallic lead were produced. As the substance supposed to be, or at least to contain carbon, had not been previously tested for disulphide of copper, which, had it been present, would have reduced some of the oxide of lead, this experiment alone cannot be regarded as conclusive. Mr. A. Dick’s Contributions to the Metallurgy of Copper. 419 About 672 grs. of electrotype copper, which had been melted under charcoal, were mixed in the state of filings with recently ignited chromate of lead, and the mixture was heated in a com- bustion tube connected with a weighed set of Liebig’s potash bulbs, and a combustion was made as in the case of an organic body. No gas was perceived to bubble through the potash solu- tion. At the end of the experiment some air was drawn through the apparatus, and the potash bulbs were reweighed. They had increased only 0°115 gr. Assuming this to be carbonic acid, it corresponds to 0-031 gr. of carbon in 672 grs. of copper. This experiment is also inconclusive. A piece of the sheet made from the mgot which had been rolled out by Mr. Forbes was cleaned by boiling in caustic pot- ash. It weighed 221:10 grs. It was laid in a platinum basin which was immersed in a solution of sulphate of copper contain- ing free sulphurie acid. The platinum basin was then con- nected with the positive pole of a galvanic battery, and a plate of copper connected with the negative pole was arranged over the basin in the solution of sulphate of copper. The whole was covered so as to exclude dust, and left till the residue of the copper in the basin was very small. It still contained a little metallic copper, which was removed by the action of a solution of perchloride of iron contaming some free hydrochloric acid. The residue was then washed by decantation, dried, and weighed. It had a very dark gray, or nearly black colour, and weighed 0:08 gr. When a portion of this was heated on platinum foil it evolved a slight and peculiar odour, glowed for an instant, and left a small incombustible residue. Another portion, weighing 0-012 gr., was placed on a very small piece of platinum foil, which was introduced into a small glass tube, one end of which dipped into a solution of caustic baryta protected from the action of the air, and the other end of which was then connected with an apparatus from which a very feeble current of air, perfectly free from carbonic acid, could be sent. Some of this air was then sent through the tube containing the slip of platinum and into the solution of caustic baryta, and it was observed that no cloudi- ness was produced in the liquid. The heat of a spirit-lamp was then applied to that part of the tube where the piece of platinum containing the powder was placed. At first a very slight subli- mate was evolved, which had the colour of sulphur, and which condensed in the cooler part of the tube. When the tempera- ture of the platinum foil on which the powder rested had reached redness, every bubble of air as it passed through the baryta water produced a precipitate. After a short time the apparatus was disconnécted, and excess of hydrochloric acid was added to the baryta solution, when the precipitate dissolved with effervescence. 420 Mr. A. Dick’s Contributions to the Metallurgy of Copper. The residue upon the platinum foil was found to weigh 0-008 gr. It had a light reddish colour, and dissolved almost entirely in hydrochloric acid, the insoluble portion being probably a trace of silica which had occurred in the copper as silicon derived from the charcoal, which, although washed with hydrochloric acid and water, was yet not chemically pure. The solution contained a trace of iron, and did not give a blue colour with ammonia; but owing to the extremely small amount of it, nothing further could be detected. The only weak point in the otherwise conclusive nature of this experiment, is that the precipitate which formed in the solution of baryta might have been sulphite, and not carbon- ate of baryta; and this gains strength from the fact, that a shght sublimate having the colour of sulphur was observed at the be- ginning of the experiment. The copper which had been em- ployed in the previous experiment was therefore examined for sulphur by dissolving it in nitro-hydrochloric acid, and after- wards boiling the solution with excess of hydrochloric acid so as to expel all nitric acid. The sulphuric acid in the solution was then precipitated, and weighed as sulphate of baryta. It was found that the copper contained 0-05 per cent. of sulphur, The very similar reaction which sulphur and carbon would have given in the preceding experiment was overlooked at the time, so that it is still an undecided question whether copper takes up any carbon by being melted under charcoal. This the writer hopes to settle soon, and will give the results im another communica- tion. The sulphur which the copper contained might have been derived from one of three sources, but it is not certain from which, viz. from the charcoal employed, the atmosphere of the furnace, or from a little of the liquid from which the copper was precipitated by the battery still remaining in its pores. The charcoal had been boiled in hydrochloric acid and washed with water, and should therefore have contained no sulphur compounds likely to exist in charcoal ; but still, as a large quantity was em- ployed to keep the metal whilst melting from running together, it is possible that the small, though important, quantity of sul- phur above mentioned may have been derived from this source. Changes produced in the appearance and properties of copper which has been melted and cast in different ways. When electrotype copper is melted and cooled in hydrogen, it may be hammered out without cracking, either when hot or cold. It is equally malleable after having been melted in charcoal, plate-glass, or common salt. When melted under charcoal and allowed to cool in the eru- cible, the surface of the piece of metal is always found to be covered with crystalline markings, especially its upper surface, Mr. A. Dick’s Contributions to the Metallurgy of Copper. 421 in the centre of which there is always a depression, owing to the contraction of the metal during solidification. In this depres- sion are generally seen a number of crystalline points. The appearance of copper which has been melted under charcoal is influenced by a number of circumstances. One of these is de- serving of special notice, because it gives rise to one of the most marked characters of overpoled copper, viz. the “rising in the mould.” When copper which has been melted under charcoal is cast into an ingot mould under ordinary circumstances, the ingot, when cooling, gives off a gas, sometimes causing projection into the air of small globules of the metal, and it solidifies with a very rough but tolerably flat surface. At other times no projection of globules takes place, and the ingot cools with a smooth surface ; but in this case it is not flat; for just at the moment of solidification a quantity of still fluid metal is squeezed from the central portion of the ingot towards the centre of the upper surface, producing a ridge along it. When such ingots are fractured, they present different appearances. In the case of the former, which solidified with a rough surface, the fracture shows numerous tubular cavities which have smooth and bright metallic surfaces. The general direction of these cavities is from the sides and bottom of the ingot towards the centre of the upper surface—that part which solidified last. Many of them may be traced from the sides to the top, where they end in little craters formed by the escaping gas at the moment the ingot was be- coming solid. In addition to these larger cavities there are in- numerable smaller ones, which cannot be discerned without the aid of a lens, by means of which the whole substance of the metal is seen to be quite vesicular. In the case of the latter ingot, which solidified with a smooth surface and a ridge on its centre, produced by the still liquid metal being squeezed from the central portion of the ingot, the fracture is somewhat different. There are no large cavities, but the whole substance of the metal is seen to be uniformly vesicular, even by the naked eye. The effect is manifestly due to the same cause, the difference arising merely from the amount of gas evolved being greater in the one case than in the other, or else from the quicker or slower cooling of the metal. Between the two extremes there are of course all degrees. Some ingots are minutely vesicular, and have a smooth flat sur- face. Others have a few larger cavities here and there among the small ones, and a smooth surface with a ridge on the centre of it. The specific gravity of a small ingot, made by melting electrotype copper under charcoal and casting under ordinary circumstances, which had this appearance, was found to be 7°851. 422 Mr. A. Dick’s Contributions to the Metallurgy of Copper. Other ingots have numerous large cavities among the small ones, and a very rough surface produced by the small craters from which the gas escaped. The specific gravity of a piece of a small ingot made like the previous one, which had this appearance, was found to be 8°211; of another piece of the same, 8°285. Of course the specific gravity will vary according to the degree in which these cavities can be filled with water when taking the specific gravity. The method pursued was to place the piece of metal in boiling water and allow it to cool under water. This was found to give higher results than when the same piece of metal was placed in water under an exhausted bell-jar; but the filling of the cavities can never be perfect, because they do not communicate. The reason assigned for the well-known fact of the evolution of a gas has been, that oxygen was dissolved by the melted metal and expelled from it during solidification (see English edition of ‘Gmelin’s Chemistry,’ vol. v. p. 402). It seems, however, certain that it cannot be oxygen, because “ dry copper” and “tough pitch copper,’ which certamly contain oxygen, give off none during solidification: further, the surfaces of the cavities when the ingot is fractured are seen to be perfectly bright and metallic, which they would not have been had oxygen been in contact with them at the temperature at which they were formed. The gas seems to be either carbonic acid or carbonic oxide, or it may be sulphurous acid, as is shown by the follow- mg experiments. If a piece of copper is melted under charcoal and allowed to cool in the crucible, it will be found that the appearance of the fracture, though affected by the rate of cooling and other things, never presents any trace of vesicular structure ; but that if, instead of allowing it to cool in the crucible, it be cast under ordinary circumstances into an ingot mould, then the fracture does show a vesicular structure. In this case, however, another element affects the result, viz. the air through which the metal passed in being poured from the crucible into the mould, and also that in contact with its surface when in the mould. Owing to this, a portion of the copper combines with oxygen; and as this gets mixed with another portion of the copper still containing carbon or sulphur, it gives rise to the gas which causes the vesicularity. The most curious point is, that the gas is given off just at the moment of solidification, or appears to be given off only at that time. But that the evolution of the gas is due to this reaction is proved by the following fact. If copper is melted under charcoal and poured through an atmosphere of coal-gas and into an ingot mould filled with the same gas, instead of the ordinary atmosphere, the metal solidifies with a bright and smooth sur- face, and when fractured shows no: trace of vesicular structure. Mr. A. Dick’s Contributions to the Metallurgy of Copper. 423 Instead of the ridge on the surface, as there is when the air is allowed free access to the metal while pouring, there-is a depres- sion. This depression shows very markedly the crystalline structure of the metal; for during the contraction attendant on solidification, the still liquid portion seems to have been drawn into the central portion of the ingot, thus rendering evi- dent the crystals which had formed ; this is especially evident in the depression. It is not improbable that the movements of different parts of the metal during solidification, by mixing por- tions containing oxygen with other portions containing carbon or sulphur, may be one reason why the gas evolved is especially evident then. This difference, produced by pouring the metal into an oxidizing or reducing atmosphere, was observed very many times; and it was found quite easy, by arranging the moulds beforehand, to cast one ingot which should be vesicular and another which should not, from the same crucible,—casting the one immediately after the other in any order. If it is desired to cast the metal which has been melted under charcoal perfectly free from cavities, the utmost precautions must be taken to exclude air. The method which was found to suc- ceed best, was to place on the crucible a lid just large enough to cover it, having two holes in its circumference. A cover of sheet iron having two holes in it was likewise placed on the mould, which was kept full of coal-gas by passing a current of it in at one hole and allowing it to escape at the other. When the metal in the crucible was melted, it was poured into the mould through one of the holes in the lid of the crucible. The small quantity of air which entered at the other to supply its place would be instantly deoxidized by the carbon, whilst the metal was prevented from absorbing oxygen while passing from the erucible imto the mould by the stream of escaping coal-gas through which it was poured, care being taken to arrange the crucible so that the metal should pass only through the gas, so as to prevent any possibility of air affecting the result. Copper which has been so cast resembles tough pitch copper in general appearance on the fractured surface. It seems to be possible to modify it slightly by the rapidity of cooling, but sufficient expe- riments on this point have not been made to admit of any gene- ralizations. It may likewise be cast with a dense structure b placing in the ingot mould some fine charcoal powder, and hold- ing the crucible as near the mould as possible, so that the metal whilst being cast is exposed to the air only for an exceedingly short time, because the imstant it reaches the bottom of the mould its surface becomes covered with the charcoal powder. This method of casting copper, after fusion under charcoal in coal-gas, so as to obtain a dense structure, might perhaps be ~ 424 Mr. A. Dick’s Contributions to the Metallurgy of Copper. successfully applied to the casting of copper cylinders for calico printing, or other objects where ereat soundness is required. The remarks which were made on page 420, in regard to the possibility of sulphur, and not carbon, having affected the result, apply equally to the evolution of gas described above. The difference in the structure of copper cast dense and porous produces other effects, such as difference in colour. This depends upon the manner in which the light falls upon the fractured surface. In certain positions the colour of the fractured surface of an ingot of vesicular structure resembles that of one of dense structure, but does not show the silky lustre. When, however, the fracture of the vesicular ingot is so arranged that the light falling upon it shall enter the small cavities and be reflected from them to the observer, it then shows a fine salmon-red colour, which the fractured surface of a dense ingot shows im no light. This evidently arises from the numerous reflexions which the light undergoes ‘in the cavities, whereby it becomes much deepened in colour. The metal seems to be possessed of the same malleability and ductility whether dense or porous; the brittleness of overpoled copper arising, as has been stated, from impurities in the metal, and not from its vesicular structure, as was proved by getting a small porous ingot, made from electrotype copper melted under charcoal and cast in air, rolled into sheet and drawn into wire. No experiments were made to ascertain whether the wire made from a porous ingot was as great in tenacity as that made from a dense one, nor as to what was the effect of corrosive liquids upon sheet made from such ingots. A porous ingot, previous to hammering or rolling, held in a vice and struck with a hammer, breaks with ease when compared with a similar one of dense structure. The specific gravity of electrotype copper, melted under char- coal and treated in various ways, is shown in the following Table :— Piece of an ingot cast under ordinary cir see 8:535 and therefore vesicular . Another piece of the same ingot. - + 8505 Wire before annealing, made from the same ingot .- 816 Same wire after annealing . . . iw! #p Sg Piece of an ingot cast in a mould containing suffi- cient charcoal powder to cover the surface of the -8°946 metal and exclude the action of the air. . Another piece of the same ingot . . . . . « 8952 Piece of another ingot cast in the same manner . 8'922 Wire before annealing, made from the latter ingot . 8°952 * Mr. A. Cayley on the Theory of Elliptic Motion. 425 Wire before annealing, made from copper which had been melted and allowed to cool in the crucible +8937 containing charcoal . Name. wire alter apnealme §.. «1. . . « » 8980 Piece of an ingot cast in coal-gas . . . . . . 8948 Another piece of the same imgot . . . . . . 8-958 From these experiments, it will be seen that tough pitch cop- per 1s copper containing an amount of oxygen equal to from 3 to 3°5 per cent. of suboxide of copper, in addition to small quan- tities of foreign metals, such as lead or antimony, or both, and that the existence of a certain amount of oxygen in it is essential to the perfect malleability of such copper. That the brittleness of overpoled copper is not due to carbon, but to the foreign metals occurring in tough pitch copper, the influence of which upon the malleability of the metal is no longer counteracted by the oxygen compounds, owing to their having been reduced by the carbon. That the porous structure of overpoled copper arises from a reaction between carbon or sulphur (for the anthracite employed on the large scale contains sulphur) absorbed by the metal in the furnace and oxygen absorbed by it whilst casting, which gives rise toa gas. That it may be cast with a dense structure by taking precautions to exclude the action of the air, such as by filling the mould with coal-gas, and pouring the metal so that it shall pass through coal-gas and not through air; and that this porosity is not the cause of the brittleness of overpoled copper. That the specific gravity of copper which has been melted under charcoal and cast with a porous structure is increased by being drawn into wire, so that it is nearly as high as wire made from copper which had a dense structure at first. That the specific gravity of copper which has been melted under charcoal and cast with a dense structure is not increased by being drawn into wire, and that the specific gravity of the wire is the same before as after annealing. LIII. Note on the Theory of Elliptic Motion. By A. Cayuny, Esq.* F, as usual, 7, 9 denote the radius vector and longitude, and p the central mass, then the Vis Viva and Force function are respectively T= 2 (!2 +770), u= cf * Communicated by the Author. Phil. Mag. 8. 4, Vol. 11. No, 74, June 1856. 2F 426 Mr, A. Cayley on the Theory of Elliptic Motion. And writing ai =a, dT ae =% 2 we have =p, @'= ao and T= 5 (2+ =i! whence putting H=T—U, the value of H is 2 And by Sir W. R. Hamilton’s theory, the equations of motion are eee ee di dp? dt or 42 2 OM «88s 0E dt dq’ dt dQ Or substituting for H its value, the equations of motion are dr We te do_ 4g dt” r®? dp_ qb di 78 dq _ a=? Putting, as usual, w=na°, and introducing the excentric anomaly uw, which is given as a function of ¢ by means of the equation nt +ce=u—esinu (s0 that uu wt) , the integral equations are q=na? /1—e, nae sin u P= THe cosa’ r=a(l1—ecosu), + kage air V1—2& sin “) ; cos u—e where the constants of integration a, e, c, a denote as usual the mean distance, the excentricity, the mean anomaly at epoch, and the longitude of pericentre. Mr. A. Cayley on the Theory of Elliptic Motion. 427 Suppose that qo, Po, 7, 9%, Mo correspond to the time ty (q is constant, so that g9=q), and write V=na?(u—uy+e sin u—e sin up). Joining to this the equations r=a(l—ecosu), ry=a(l—ecos us), 6—0,= tan-} ( V1 —e* sin 2) epgteul WL, sin wo), cos u—e cos u—e U, Up, e will be functions of a, 7,79, 0, A, and consequently (n being throughout considered as a function of a) V will be a function of a, 7,79, 0, 0). The function V so expressed as a function of a, 7, 79, 8, 4 is, in fact, the characteristic function of Sir W. R. Hamilton, and according to his theory we ought to have dV = jn? a(t—t,)da +-pdr + qd0 —podry— qo. To verify this, I form the equation dV =j3na(u—u) + esinu—e sin u,)da +na*[(1+e cos u)du—(1 +e cos u,)duy] +na*(sin u— sin u9)de nae sin u Ton {7 — (1—e cos u)da—ae sin u du +a cos ude} 1—ecosu nae sin u > 0 wee! ats iG 1—ecosu, {dry— (1 —ecosug)da—aesin ugduy+ acos ude} 0 1 /1—e?(1—ecosu) a : > ———- [(1-e*)d de} \. V1—e(1—ecosug) Cie eg ete al} The coefficient of du on the right-hand side is +naz/1—ée { _ [(1—e?)du+sin ude] —d0,+ nave? sin?u —__na*(1 —e?) l—ecosu 1—ecosu 1 —e?+¢? sin? “) l—ecosu 4 which vanishes, and similarly the coefficient of dug also vanishes : the coefficient of de is the difference of two parts, the first of which is na*(1 +e cos u) — =na(1 +ecosu— naesinucosu na? sin u i na" Sin U-- —— — — + l—ecosu l—ecosu ae 1l—ecosu =na* sin u eT upyant . which yanishes, and the second part in like manner also vanishes ; 2F2 428 The Rey. S. Haughton on the Solar and Lunar the coefficient of da is the difference of two parts, the first of which is Jna(u+e sin vu) —nae sin u=Zna(u—e sin wu), and the second is the like function of u); the entire coefficient therefore is } na(u—uy—esinu+esin wu). We have therefore dV = na(u—uy—e sin u+ e sin Uy)da nae sin u ]—ecosu nae SIN Up ~ 1—ecos Uo or what is the same thing, dV =3n?a(t—t))da+ pdr + qd0-—podro— qo , the equation which was to be verified. 2 Stone Buildings, March 28, 1856. dr +na? V1 —e? dO dry—na® V1 — 7d, ; LIV. On the Solar and Lunar Diurnal Tides of the Coasts of Ireland. By the Rev. Samurt Haventon, Fellow of Trinity College, Dublin. . {Coneluded from p. 272.] Srction XIII. Mean depth of Sea deduced from the Diurnal Tide. QGoME interesting comparisons of the solar and lunar tides may be made, deduced from the preceding results; with respect to the relative influence of the sun and moon, with respect to the tidal intervals and establishments, and with reference to the age of the lunar tide; and from each of these the mean depth of the sea may be deduced. 1. Relative effects of the Sun and Moon. The following Table is formed from the constants already given :— 7 Relative effects of the Sun and Moon. | Solar Lunar Ss. coefficient. coefficient. M ft. ft. Caherciveen ...... 0-335 0-480 0:698 Bunown ......+0.08. 0°342 | 0°646 0-529 Rathmullan ...... 0-315 0°6382 0-498 POrtrUsiss-sccsenaes 0°342 | 0519 0-659 Cushendall ......... 0°376 0-381 0427 Donaghadee ...... 0383 0:868 0-441 Kingstown ......... 0°348 0-690 0:504 Courtown ......... 0-410 0-719 0-570 Dunmore East ... 0-192 0°441 0°436 Mea tet Zeiss ee LE SER WL Ose 0-53805 Diurnal Tides of the Coasts of Ireland. 429 The mean ratio of S to M here found, shows that the sun’s effect on the diurnal tide is somewhat more than half the moon’s effect. In Mr. Airy’s discussion of the semidiurnal tides of Ireland, the following mean ratios of S to M are found* :— Page 835 . . 0°33 deduced from Heights. wine FENDA jase oir Ore ee ee 42 . . 0°35 deduced from Times. ioe LOB C -. OSS > Mean . . 0°35 According to the statical theory of the tides, the ratio of the solar to the lunar effect should be the same for the diurnal and for the semidiurnal tides; but according to the dynamical theories of the tides, the coefficients in the solar and lunar tides depend in a different manner on the depth of the sea, and therefore the ratios deduced from the diurnal and semidiurnal tides should be different. According to Mr. Airy’s theory of tides with friction, the ratios of the solar to the lunar coefficients in the semidiurnal and diurnal tides are given by the following equations :—- ne _ yk Diurnal solar coefficient S | d® Pe 6b (8) Diurnal lunar coefficient’ M * D? nb ay iT -oete g b nek Semidiurnal solar coefficient Sd? gb ee SK X (9) Semidiurnal lunar coefficient M ~ D? nb ta k ‘ g b In these equations— S, M are the masses of the sun and moon ; d, D are the distances of the moon and sun ; n, n' ave the angular velocities of the sun and moon ; k is the mean depth of the sea; b is the mean radius of the earth ; g is the force of gravity. Substituting the known values of all the quantities, excepting k, we find,— k 4 (ao Perey, ade Solidiurnal coefficient lege b Uageeae aaa OP os Laveen Bl ccs co 0-00845 —4.5 * Transactions of Royal Society, 1845. 430 The Rev. 8S. Haughton on the Salar and Lunar k Semidiurnal solar coefficient _ 0-47 pg e3 — b u Semidiurnal lunar coefficient. i: a 0:00845 — + Substituting in equation (10) the mean value of the ratio of solar and lunar coefficients deduced from our diurnal tides, we find ao aa 6° 778 _The value of the ratio of the semidiurnal solar to the semi- diurnal lunar coefficient given by Laplace, Mécanique Céleste, 3 k=5-12 miles. F : 1 : vol. v. p. 206 (Paris, 1825), is 35333 * value derived from the famous observations made at Brest, on the Atlantic semi- diurnal tides. Substituting this value in equation (11), we find,— HS he! b ~ 780’ The agreement of these results, derived from such different data, is very remarkable, and cannot be considered as accidental. 2. The Lunitidal and Solitidal Intervals. Arranging the intervals already given in a table, and reducing them to the Greenwich meridian to obtain the establishments, we find,— k=5:'07 miles. Diurnal Tidal Intervals and Establishments. Lunitidal Solitidal Lunitidal Solitidal interval. interval. establishment. | establishment. h m h m h m h m Caherciveen ...... 0 6 3 25 0 46 4 8 Bunown ......ss0000 0 31 2 52 1 11 ata +4 Rathmullan ...... 4 6 9 40 4 36 10 10 POnirnshisanccsccssss 3 43 11 30 4 9 ll 56 Cushendall ......... 7 16 1] 25 7 AO 1] 49 Donaghadee ...... 7 A9 11 12 8 li 1] 34 Kingstown ......... 7 39 10 26 8 3 10 50 Courtown ......... 5 28 § 2 8 41 0 30 17:37 12:88 Cushendall ......... 5 8 0 35 8°80 12°82 Donaghadee ...... 4 35 0 48 5:73 12°75 Kingstown ......... 4 45 1 34 3:03 12:50 Dunmore East ... 10 36 6 45 1:57 11-40 SVISANIC ES cops sesh seee| Pura visas eo [avn Te enesecd, om Ihe ebosess 11-986 These depths agree remarkably well together; and although they differ widely from the result obtained from heights, and from the result of Laplace’s ‘ Brest Observations on the Semi- diurnal Tide,’ yet we shall find them confirmed in a remarkable manner by the depths of the sea, deducible from the age of the lunar tide. 3. Age of the Lunar Diurnal Tide. Arranging the ages of the tides given in the several sections of this paper, we find,— * Airy, ‘Tides and Waves,’ p. 332. 432 On the Solar and Lunar Diurnal Tides of the Coasts of Ireland. Age of Lunar Diurnal Tide. High water. Low water. doh d h Caherciveen ...... ee! 417 Bunown ....80..000- a 4 9 Rathmullan ...... 5 10 4 20 Portepshycisessseess B29 419 Cushendall ......... 6 19 5.3 Donaghadee ...... 6 5 5 2 Kingstown ......... 617 411 Courtown ......... 6 22 3 12 Dunmore East .. 5 19 5 14 A series of values for the depth of the sea may be obtained by comparing the age of the lunar diurnal tide with the lunidiurnal acceleration of high water already given, as follows:— By the theory of tides, including friction*, it appears that— Age of lunidiurnal tide _ + gkm? (14) Acceleration of lunidiurnal tide — 7? —gkm” 2 denoting the angular velocity of the moon, and the other letters remaining as before. Introducing the numerical values of the known quantities, we find, expressing / in miles,— Age of lunidiurnal tide __12:9388 +k Acceleration of lunidiurnal tide ~ 12°988—k' * By the aid of this equation, we find the depths of the sea, calculated in the followmg Table :— Mean depth of Sea deduced from Age of Lunar Tide. (15) Mean age. Acceleration. Ratio. Depth of sea. hours. hours. miles. Caherciveen ...... 1185 12°30 9-63 10°50 Bunown .......0000. 105 11:88 8-84 10°31 Rathmullan ...... 123 8:30 14-82 11°30 PortimMsht /.Aveee sc 122 8°68 14:05 11-22 Cushendall ......... 143 5:13 27°87 12-04 Donaghadee ...... 135°5 4:58 29°58 12-09 Kingstown ......... 134 4-75 28-21 12°05 Dunmore East 136°5 10-60 12°88 11:07 WERT Meee ctevesesti ce" doteceMie tH ce 2s cpvno Ayr tll po peeees 11-322 The results just obtained agree very well with each other, and with the results obtained from the diurnal solitidal and lunitidal intervals; but both results differ widely from the mean depth deduced from heights. How are we to reconcile this difference ? Although this question is difficult to answer fully, yet it should * Airy, ‘Tides and Waves,’ p. 333. Prof. Thomson on the Dynamical Theory of Heat. 433 be observed that probably the depth inferred from tidal intervals and ages may be the depth of the sea at a greater distance from the coast; while the depth deduced from heights is the depth of the sea after it has begun to shoal, the tide being composed partly of a derivative and partly of the original Atlantic tide. Is it impossible, or improbable, that the result deduced from times, viz. 11-65 miles, is the depth of the central channel of the South Atlantic and of the Antarctic Oceans, while the depth deduced from heights, viz. 5°12 miles, is the mean depth of the whole Atlantic? These and many other interesting questions suggest them- selves, which I shall leave for the consideration of those concerned in the mathematical theory of the tides. The separation of the effects of the sun and moon in the diurnal tide, which has never before been made, must prove of value in correcting the bases on which the mathematical theories of the tides rest; theories which, notwithstanding the amount of mathematical genius ex- ercised on them, must be considered as still in a most imperfect and unsatisfactory condition. Trinity College, Dublin, May 7, 1856. LV. On the Dynamical Theory of Heat.—Part V1. Thermo- electric Currents. By Wi1tu1am Tuomson, M.4A., Professor of Natural Philosophy in the University of Glasgow. [Concluded from p. 388. ] §§ 156-170. On the Thermal Effects and the Thermo-electric Excitation of Electrical Currents in Homogeneous Crystalline Solids. 156. ae Propositions I. and II., investigated above, sugges t the kind of assumptions to be made regarding the reversible thermal effects of currents in uniformly heated crystal- line solids, and the electromotive forces induced by any thermal circumstances which cause inequalities of temperature in different parts. The formule expressing these agencies in the particular case which we have now investigated, guide us to the precise forms required to express those assumptions in the most general possible manner. 157. Let us first suppose a rectangular parallelopiped (a, 4, ¢) of homogeneous crystalline conducting matter, completely sur- rounded by continuous metal of the standard thermo-electric quality touching it on all sides, to be traversed in any direction _ by a uniform electric current, of which the intensity components parallel to the three edges of the parallelopiped are A, 7, j, and to 434: Prof. Thomson on the Dynamical Theory of Heat. be kept in all points at a uniform temperature ¢. Then taking ¢, 9, yr to denote the thermo-electric powers of bars of the sub- stance cut from directions parallel to the edges of the parallelo- piped, quantities which would be equal to one another in what- ever directions those edges are if the substance were non-cry- stalline; and 6’, 0", g', 6", ~', w" other elements depending on the nature of the substance with reference to the directions of the sides of the parallelopiped, to which the name of thermo- electric obliquities may be given, and which must vanish for every system of rectangular planes through the substance if it be non-crystalline, we may assume the following expression for the reversible thermal effects of the current :— t Als Qe, = be (hO+ ig" +7") t i iat Qe, a) = CaF (LO ip +p") ‘eopakes (31), t ee QU, = ab + (LO +24! +7) J where Qu, .), Qe, a), Qa.) denote quantities of heat absorbed per second at the sides by which positive current components enter, or quantities evolved in the same time at the opposite sides. Hence if the opposite sides be kept at different temperatures, currents will pass, unless prevented by the resistance of surround- ing matter; and the electromotive forces by which these currents are urged in directions parallel to the three edges of the paral- lelopiped have the following expressions, in which wa, vb, and we denote the difference of temperature between corresponding points in the pairs of sides be, ca, and ab respectively reckoned positive, when the temperature increases in the direction of posi- tive components of current :— F=—d(ud!+vp+ud') G= —e(up! +- op" +0) The negative signs are prefixed, in order that positive values of the electromotive components may correspond to forces in the direction assumed for positive components of current. 158. The most general conceivable elementary type of crystal- line thermo-electric properties is expressed in the last equations, along with the equations (81) by which we arrived at them; and we shall see that every possible case of thermo-electric action in solids of whatever kind may be investigated by using them with values, and variations it may be, of the coefficients ¢, 0, &c., E= —a(ud + v6! + w6") i (32). Prof. Thomson on the Dynamical Theory of Heat. 435 suitable to the circumstances. It might be doubted, indeed, whether these nine coefficients can be perfectly independent of one another; and indeed it might appear very probable that they are essentially reducible to six independent coefficients, from the extraordinary nature of certain conclusions which we shall show can only be obviated by supposing =", Marl, and saw". Before going on to investigate any consequences from the unre- stricted fundamental equations, I shall prove that it is worth while to do so, by demonstrating that a metallic structure may be actually made, which, when treated on a large scale as a con- tinuous solid, according to the electric and thermal conditions specified for the substance with reference to which the equations (31) and (32) have been applied, shall exhibit the precise electric and thermal properties respectively expressed by those sets of equa- tions with nine arbitrarily prescribed values for the coefficients 0, d, &e. 159. Let two zigzag linear conductors of equal dimensions, each consisting of infinitely short equal lengths of infinitely fine straight wire alternately of two different metals, forming right angles at the successive junctions, be placed in perpendicular planes, and not touching one another at any point, but with a common straight line joining the points of bisection of the small LN NI a ee straight parts of each conductor. Let an insulating substance be moulded round them so as to form a solid bar of square sec- tion, just containing the two zigzags imbedded in it in planes parallel to its sides. Although this substance is a non-conductor of electricity, we may suppose it to have enough of conducting power for heat, or the wires of the electric conductors to be fine enough, that the conduction of heat through the bar when it is unequally heated may be sensibly the same as if its substance were homogeneous throughout, and consequently that the elec- tric conductors take at every point the temperatures which the bar would have at the same point if they wereremoved. Let an infinite number of such bars, equal and similar, and of the same substance, be constructed; and let a second system of equal and similar bars be constructed with zigzag conductors of different metals from the former; and a third with other different metals ; the sole condition imposed on the different zigzag conductors being that the two in each bar, and those in the bars of different systems, exercise the same resistance against electric conduction. } 436 Prof. Thomson on the Dynamical Theory of Heat. Let an infinite number of bars of the first set be laid on a plane parallel to one another, with intervals between every two in order, equal to the breadth ofeach. Lay perpendicularly across them an infinite num- berof bars of thesecondsystem similarly disposed relatively to one another; place on these again bars of the first system, constituting another layer si- milar and parallel to the first; on this, again, a layer similar and parallel tothesecond; and ¢ so on till the thickness of the superimposed layers is equal to the length ofeach bar. Then let an infinite number of the bars of the third system be taken and pushed into the square prismatic apertures perpendicular to the plane of the layers; the cubical hollows which are left (not visible in the diagram) being previously filled up with insulating matter, such as that used in the composi- tion of the bars. Let the complex solid cube thus formed be coated round its sides with infinitely thin connected sheets of the stand- ard metal, so thin that the resistance to the conduction of elec- tricity along them is infinitely great, compared to the resistance to conduction experienced by a current traversing the interior of the cube by the zigzag linear conductors imbedded in it. (For instance, we may suppose the resistance of four parallel sides of the cube to be as great as, or greater than, the resistance of each one of the zigzag linear conductors.) Let an infinite number of such cubes be built together, with their structural directions pre- served parallel, so as to form a solid, which, taken on a large scale, shall be homogeneous. A rectangular parallelopiped, abc, of such a solid, with its sides parallel to the sides of the elemen- tary cubes, will present exactly the thermo-electrie phenomena expressed above by the equations (31) and (82), provided the thermo-electric powers @,, a', o,", @,!", @, Ba, Bq’, wl, and @3, G3, os, ws!" of the metals used in the three systems fulfil the following conditions — HAt+e +o," +0)'")=8, 7) 1(e,—a,)=6', 1a," —o,!")=6", | Seier tye ee . (38). (o.— Bq) = ¢! 5) 4(@o —o,!"") apg r ( ) Hoyt a+! +05!) | (a,— a3) =", ¢(o3'—o3")=" J Bl Ble Ble a laelies Prof. Thomson on the Dynamical Theory of Heat. 437 160. To prove this, let us first consider the condition of a bar of any of the three systems, taken alone, and put in the same thermal circumstances as those in which each bar of the same system exists in the compound mass. If, for instance, we take a bar of the first system, we must suppose the temperature to vary at the rate wu per unit of space along its length; at the rate v across it, perpendicularly to two of its sides; and at the rate w across it, perpendicularly to its other two sides. If / be its length, and e the breadth of each side, its ends will differ in temperature by u/; corresponding points in one pair of its sides by ve, and corresponding points in the other pair of sides by we. Now it is easily proved that the longitudinal electromotive force (that is, according to the definition, the electromotive force be- tween conductors of the standard metal connected with its ends) would, with no difference of temperatures between its sides, and the actual difference ud between its ends, be equal to (a, + a,'Jul, if only the first of the zigzag conductors existed imbedded in the bar, or equal to 3(a,!'+ a,!")ul, if only the second ; and since the two have equal resistances to conduction, and are connected by a little square disc of the standard metal, it follows that the longitudinal electromotive force of the actual bar, with only the longitudinal variation of temperature, is I 1(@,+a,! +o," +a!" Jul. Again, with only the lateral variation ve, we have in one of the zigzags a little thermo-electric battery, of a number of elements : tog neste: : amounting to the greatest integer im 5p which is sensibly equal to a2 since the value of this is infinitely great; the electromo- 2e S tive force of each element is (@,—2')ve; and therefore the whole electromotive force of the zigzag is - x (o—a,|)ve, or Ax (a, — a). This battery is part of a complete circuit with the little terminal squares and the other zigzag, and therefore its electromotive force will sustain a current in one direction through itself, and in the contrary through the second zigzag; but since the resist- ances are equal in the two zigzags, and those of the terminal connexions may be neglected, just half the electromotive force of the first zigzag, being equal to the action and reaction between the two parts of the circuit, must remain ready to act between conductors applied to the terminal discs of the standard metal. In the circumstances now supposed, the second zigzag is through- out at one temperature, and therefore has no intrinsic electro- 438 Prof. Thomson on the Dynamical Theory of Heat. ’ motive force; and the resultant intrinsic electromotive force of the bar is therefore 4U(a,—2;!)v. Similarly, if there were only the lateral variation we of tempera- ture in the bar, we should find a resultant longitudinal electro- motive force equal to L(a,"—a!"\w. If all the three variations of temperature are maintained simul- taneously, each will produce its own electromotive force as if the others did not exist, and the resultant electromotive force due to them all will therefore be fle teyl toy! +oM)ut (@,—a)04 (a]!—m"\w}. This being the electromotive force of each bar of the first system in any of the cubes composing the actual solid, must be the component electromotive force of each cube in the direction to which they are parallel, and therefore ax{ (my +o +2," +a,")u+ (2 —ay/)v+ (@"—a,")w} must be the component electromotive force of the entire paral- lelopiped in the same direction. Similar expressions give the component electromotive forces parallel to the edges b and ec of the solid, which are similarly produced by the bars of the second and third systems, and we infer the proposition which was to be proved. 161. Cor. By choosing metals of which the thermo-electric relations, both to the standard metal and to one another, vary, we may not only make the nine coefficients have any arbitrarily given values for a particular temperature, but we may make them each vary to any extent with a given change of tempe- rature. 162. For the sake of convenience in comparing the actual phenomena of thermo-electric force in different directions pre- sented by an unequally heated crystalline solid, let us now, instead of a parallelopiped imbedded in the standard metal, con- sider an insulated sphere of the crystalline substance, with sources of heat and cold applied at its surface, so as to maintain a uni- form variation of temperature in all lines perpendicular to the parallel isothermal planes. Let the rate of variation of tempera- ture per unit of length, perpendicular to the isothermal surfaces, be qg, and let the cosines of the inclinations of this direction to the three rectangular directions in the substance to which the edges of the parallelopiped first considered were parallel, and which we shall now call the lines of reference, be /, m, n respect- Prof, Thomson on the Dynamical Theory of Heat. 439 ively. Then if we take gi=u, gm=v, gn=u, the substance of the sphere will be in exactly the same thermal condition as an equal spherical portion of the parallelopiped ; and it is clear that the preceding expressions for the component electromotive forces of the parallelopiped will give the electro- motive forces of the sphere between the pairs of points at the extremities of diameters coinciding with the rectangular lines of reference, if we take each of the three quantities, a, b, c, equal to the diameter of the sphere. Calling this unity, then we have —HK=u0 +20 +wé! —F=u¢"+v¢ +g} —G=up'+op" + According to the definition given above (§ 144, Def. 3), it appears that these quantities, E, F, G, are the three components of the intrinsic electromotive force at any point in the substance, whether the portion of it we are considering be limited and spherical, or rectangular, or of any other shape, or be continued to anyindefinite extent by homogeneous or heterogeneous solid conducting matter with any distribution of temperature through it. The compo- nent electromotive force P along a diameter of the sphere in- clined to the rectangular lines of reference at angles whose cosines are /, m, n, is of course given by the equation P=Hl4Fm+Gn°>. . . 1. . (85), which may also be employed to transform the general expressions for the components of the electromotive force to any other lines of reference. 163. A question now naturally presents itself: Are there three principal axes at right angles to one another in the substance possessing properties of symmetry, with reference to the thermo- electric qualities, analogous to those which have been established for the dynamical phenomena of a solid rotating about a fixed point, and for electrostatical and for magnetic forces, in natural crystals or in substances structurally crystalline as regards elec- tric or magnetic induction? The following transformation, sug- gested by Mr. Stokes’s paper on the Conduction of Heat in Crystals*, in which a perfectly analogous transformation is ap- plied to the most general conceivable equations expressing flux of heat in terms of variations of temperature along rectangular lines of reference in a solid, will show the nature of the answer. 164. The direction cosines of the line of greatest thermal variation, or the perpendicular to the isothermal planes, are (34), * Cambridge and Dublin Mathematical Journal, Noy. 1851. 440 Prof. Thomson on the Dynamical Theory of Heat. uvw —, —, —, where g, denoting the rate of variation of temperature Vr in the direction of that line, is given by the equation g= 4: v2 w?) =. oo. 1 Taking these values for 7, m, n, in the preceding general expres- sion for the electromotive force in any direction, we find a at Ou? + hv? + rw? + (! + "ow + (el + O" wu + (8+ 6" uv} the negative sign being omitted on the understanding that P shall be considered positive when the electromotive force is from hot to cold in the substance. This formula suggests the follow- ing changes in the notation expressing the general thermo-elec- tric coefficients :— df! tapl= =20); ap! + 6" = 2¢,, A+o"= QW, 37 —¢'+ typ"= 26 —Wt+ 6! =2n, SS hee gp! =23 HN 3 ( )s which reduce the general equations, and the formula itself which suggests them, to —E=0u +\0+ w+ (nw—Sv) —F=yu+dv +0,w += ~G= gut Ov + yw + (So —m) Pes 7 (Ou? + hv? + pw? + 26,0w + 2hywut pur) . (39). (38), 165. The well-known process of the reduction of the general equation of the second degree shows that three rectangular axes may be determined for which the coefficients 0), $,, x, in these expressions vanish, and for which, consequently, the equations become —F=qv + (Su —Ww) —G=wWw+ (%& —7u) P== (Ou? + gu +p?) AR arr —E=0u + (nw —Sv) 1 166. The law of transformation of the binomial terms (yw—4v), &e. in these expressions is clearly, that if p denote a quantity independent of the lines of reference, and expressing a specific thermo-electric quality of the substance, which I shall call its thermo-electric rotatory power, and if d, «, v denote the inclina- tions of a certain axis fixed in the substance, which I shall call its axis of thermo-electric rotation, to any three rectangular lines Prof. Thomson on the Dynamical Theory of Heat. 44.1 of reference, then the values of &, », 3 for these lines of reference are as follows :— f=pcosr, n=pcosy, S=pcosyv. If z denote the inclination of the direction (¢, % 2), in which the temperature varies most rapidly, to the axis of thermo-elec- tric rotation, and if «, 8, y denote the angles at which a line perpendicular to the plane of this angle i is inclined to the axes of reference, we have nw —Iv=pq sini cos @ Su—fw=pq sini ona & —nu=pq sini cosy Hence we see that the last terms of the general formula for the component electromotive forces along the lines of reference ex- press the components of an electromotive force acting along a line perpendicular both to the axis of thermo-electric rotation, and to the direct line from hot to cold in the substance, and equal in magnitude to the greatest rate of variation of tempera- ture perpendicular to that axis, multiplied by the coefficient p. 167. Or again, if we consider a uniform circular ring of rect- angular section, cut from any plane of the substance inclined at an angle X to a plane perpendicular to the axis of thermo-electric rotation, and if the temperature of the outer and inner cylindrical surfaces of this ring be kept each uniform, but different from one another, so that there may be a constant rate of variation, q, of temperature in the radial direction, but no variation either tan- gentially or in the transverse direction perpendicular to the plane of the ring, we find immediately, from (42), that the last terms of the general expressions indicate a tangential electromotive force, equal in value to pq cosX, acting uniformly all round the ring. This tangential force vanishes if the plane of the ring contain the axis of thermo-electric rotation, and is greatest when the ring is in a plane perpendicular to the same axis. 168. The peculiar quality of a solid expressed by these terms would be destroyed by cutting it into an infinite number of plates of equal infinitely small thickness, inverting every second plate, and putting them all together agam into a continuous solid, in planes perpendicular to the axis of thermo-electric rotation ; a process which would clearly not in any way affect the thermo- electric relations expressed by the first term of the general expres- sions for the components of electromotive force ; and it is there- fore of a type, to which also belongs the rotatory property with reference to light discovered by Faraday as induced by magnet- ization in transparent solids, which I shall call dipolar, to distin- Phil, Mag. 8. 4, Vol. 11, No, 74, June 1856, 2G 442 Prof. Thomson on the Dynamical Theory of Heat. guish it from such a rotatory property with reference to light as that which is naturally possessed by many transparent liquids and solids, and which may be called an isotropic rotatory pro- perty. The axis of thermo-electric rotation, since the agency distinguishing it as a line also distinguishes between the two directions in it, may be called a dipolar axis; so may the axis of rotation of a rotating rigid body*, or the direction of magnet- ization of a magnetized element of matter; and its general type is obviously different from that of a principal axis of inertia of a rigid body, or a principal axis of magnetic inductive capacity in a crystal, or a line of mechanical tension in a solid; any of which may be called an isotropic axis. 169. The general directional properties expressed by the first terms of the second members of (40) are perfectly symmetrical regarding the three rectangular lines of reference, and are of a type so familiar that they require no explanation here. We conclude that every substance has three principal isotropic axes of maxi- mum and minimum properties regarding thermo-electric power, which are at right angles to one another ; but that it is only for a particular class of conceivable substances that the thermo- electric properties are entirely symmetrical with reference to these axes; all substances for which the rotatory power, p, does not vanish, having besides a dipolar axis of thermo-electric rota- tion which may be inclined in any way to them. 170. These principal isotropic axes lose distinction from all other directions in the solid when the thermo-electrie powers along them (the values of the coefficients 6, ¢, yr) are equal; but a rotatory property, distinguishing a certain line as a dipolar axis, may still exist. By § 159, we see how metallic structures possessing any of these properties (for imstance, having equal thermo-electric power in all directions, and possessing a given rotatory power, p, in a given direction about a given system of arallel lines) may be actually made. 171. (Added, July 1854.] It is far from improbable that a piece of iron in a state of magnetization, which I have, since § 147 was written, ascertained to possess different thermo-electric properties in different directions, may also possess rotatory thermo-electric power, distinguishing its axis of magnetization, * (Added, Liverpool, Sept. 27, 1854.]|—As is perfectly illustrated by M. Foucault’s beautiful experiment of a rotating solid, placing its axis parallel to that of the earth’s, and so turned that it may itself be rotating in the same direction as the earth; which the meeting of the British Asso- ciation just concluded has given me an opportunity of witnessing. + (Added, Sept. 13, 1854.]—By an experiment made to test its existence, which has given only negative results, I have ascertained that this “rota- tory power,” if it exists in inductively magnetized iron at all, must be very Prof. Thomson on the Dynamical Theory of Heat. 443 which is essentially, in its magnetic character, dipolar, as thermo- electrically dipolar also. §$ 172-181. On the general equations of Thermo-electric Action in any homogeneous or heterogeneous crystallized or non-crystal- lized solid. 172. Let ¢ denote the absolute temperature at any point, 2, y, 2, of a solid. Let 0, d, w, 0, d', W', 6", 6", w" be the values of the nine thermo-electric coefficients for the substance at this point, quantities which may vary from point to point, either by heterogeneousness of the solid, or in virtue of non- uniformity of its temperature. Let h, i, 7 be the components of the intensity of electric current through the same point (2, y, 2). 173. Then, applying equations (31) of § 157 to infinitely small, contiguous, rectangular parallelopipeds in the neighbour- hood of the point (a, y, z), and denoting by H dx dy dz the resultant reversible absorption of heat occasioned by the electric current across the infinitely small element dx dy dz, we find H=S{ 0+ ig! LA) +200 + ib +9") +710" +18! +74) f(A). 174. By the analysis of discontinuous functions, this expres- sion may be applied not only to homogeneous or to continuously varying heterogeneous substances, but to abrupt transitions from one kind of substance to another. Still it may be convenient to have formule immediately applicable to such cases, and therefore I add the following expression for the reversible thermal effect in any part of the bounding surface separating the given solid from a solid of the standard metal in contact with it :— Q=Fip(he + ig! jp!) + q(hO' + ip typ") +r(hO" +i! +yy)h- (44), where Q denotes the quantity of heat absorbed per second per unit of surface at a point of the bounding surface, and (p, 9,7) the direction cosines of a normal to the surface at the same point. 175. Equations (34) give explicitly the intrinsic electromotive force at any point of the solid when the distribution of tempera- ture is given; but we must take into account also the reaction proceeding from the surrounding matter, to get the efficient electromotive force determining the current through any part of the body. This reaction will be the electrostatical resultant force due to accumulations of electricity at the bounding surface and in the interior of the conducting mass throughout which the small in comparison with the amount by which the thermo-electric power in the direction of magnetization differs from the thermo-electric power of the same metal not magnetized. G2 444. Prof. Thomson on the Dynamical Theory of Heat. electrical circuits are completed. Hence if V denote the elec- trical potential at (#, y, z) due to these accumulations, the com- ponents of the reactional electromotive force are dV dV dV. dx’ dy’ dz” and the components of the efficient electromotive force in the solid are therefore dV dV dV uh ax’ tate G—— where E, F, G are given by the following equations, derived from dt dt dt (34) by substituting for u, v, w their values ayy de’ in terms of the notation now introduced :— _ tt dt gy , at on E=7 6 ee +70 7 eh Ade Og lees dt ,, F=7¢ Riggs gre s: at, Gk eae (45). Sp yy ye a OR an) ais dae 176. The body, being crystalline, probably possesses different electrical conductivities in different directions, and the relation between current and electromotive force cannot, without hypo- thesis, be expressed with less than nine coefficients. These, which we shall call the coefficients of electric conductivity, we shall denote by «, X, &e.; and we have the following equations, expressing by means of them the components of the intensity of electric current in terms of the efficient electromotive force at any point of the solid :— es dV (nav n( ax) i=)! (u—) +r (r-7) +n ees - (46). 3 dV dV dV ere lak at aks 3 Di hats pat AL ver (B Te) tH (F 7) tH (c z=) These equations (45) and (46), with dh di, dx t dy * dz which expresses that as much electricity flows out of any portion of the solid as into it, in any time, (in all seven equations,) are sufficient to determine the seven functions KH, F, G, V, A, é, 7, = een | Prof. Thomson on the Dynamical Theory of Heat. 445 for every point of the solid, subject to whatever conditions may be prescribed for the bounding surface, and so to complete the problem of finding the motion of electricity across the body in its actual circumstances ; provided the values of = La iad are x dy’ dz known, as they will be when the distribution of temperature is given. We may certainly, in an electrical problem such as this, suppose the temperature actually given at every point of the solid considered, since we may conceive thermal sources distributed through its interior to make the temperature have an arbitrary value at every point. 177. Yet practically the temperature will, in all ordinary cases, follow by conduction from given thermal circumstances at the surface. The equations of motion of heat, by which, along with those of thermo-electric force, such problems may be solved, are as follows :—(1), three equations, c=— roe Ey why) dy dz | dt dt 2 ai pl tS | Aeath Ce ges one es: ‘ (Wee E405 ° a dt dt dt PP fis, WO ied = (we. non dy +m) to express the components & y, 3 of the “flux of heat” at any point of the solid, in terms of the variations of temperature i ie #) multiplied by coefficients k, 7, m, Kk’, &e., which may be called the nine coefficients of thermal conductivity of the substance ; and (2), the single equation de dy ds _ da’ dy * ds <5 {Zio + ig" iy) + Zia +i iy + Lao sig +a) } I la IVI Ty J dz J H{i(s-2) i(e-2)as(0-2)} of which the first member expresses the rate at which heat flows out of any part of the solid per unit of volume; and the second member, to which it is equated, the resultant thermal agency (positive when there is, on the whole, evolution at xyz) produced by the electric currents. 178. The general treatment of these eleven equations, (45), (46), (47), (48), (49), leads to two non-linear partial differential 446 Prof. Thomson on the Dynamical Theory of Heat. equations of the second order and degree for the determination of the functions ¢ and V. 179. It may be remarked, however, that the second term of the second member of (49), when the prefixed negative sign is removed, expresses the frictional generation of heat by currents through the solid, and will therefore, when the electromotive forces in action are solely thermo-electric, be very small, even in comparison with the reversible generation and absorption of heat in various parts of the body, provided the differences of tem- perature between these different localities are small fractions of the temperature, on the absolute scale from its zero. Excepting, then, cases in which there are wide ranges (for instance, of 50° C. or more) of temperature, the second principal term of the second. member of (49) may be neglected, and the partial differential equations to which ¢ and V are subject will become linear; so that one of the unknown functions may be readily eliminated, and a linear equation of the fourth order obtained for the deter- mination of the other. 180. Further, it may be remarked that probably in most, if not in all known cases, the reversible as well as the frictional thermal action of the currents, when excited by thermo-electric force alone, is very small in comparison with that of conduction, perhaps quite insensible. [See above, § 106.] Hence, except when more powerful electromotive forces than the thermo-elec- tric forces of the solid itself, and of its relation to the matter touching it round its surface, act to drive currents through it, we may possibly in all, certainly in many cases, neglect the entire second member of (49) without sensible loss of accuracy ; and we then have a differential equation of the second ane for the determination of the temperature in the interior of the body, simply from ordinary conduction, according to the condi- tions imposed on its surface. To express these last conditions generally, a superficial application of the three equations (48) with their nine independent coefficients is required. 181. When ¢ is either given or determined in any way, the solution of the purely electrical problem is, as was remarked above, to be had from the seven equations (45), (46), and (47). These lead to a single partial differential equation of the second order for the determination of V through the interior, subject to con- ditions as to electromotive force and electrical currents across the surface, for the expression of which superficial applications of (45) and (46) will be required. When V is determined, the solution of the problem is given by (45) and (46), expressing respectively the electromotive force and the motion of electricity through the solid. [ 447 ] LVI. On the Discovery of the true form of Carnot’s Function. By Professor WiLi14m THomson. To the Editors of the Philosophical Magazine and Journal. _ Oakfield, Moss Side, Manchester, GENTLEMEN, May 12, 1856. CLAUSIUS, in a letter of date March 20, 1856, ad- e dressed to yourselves, and published this month in your Magazine, objects to a statement he supposes me to have made in 1851, and to have frequently repeated since that time, that Mr. Joule had discovered “the theorem, that Carnot’s func- tion (c or ~) ‘is nothing more than the absolute temperature multiplied by the equivalent of heat for the unit of work.” He attributes the discovery of the true form of Carnot’s function to Holtzmann, who gave the formula referred to in a paper which appeared as early as 1845; but he believes that in his own paper “On the Moving Force of Heat,” communicated to the Berlin Academy in 1850, the principles upon which that formula is based were first correctly explained. Allow me to answer the charge he makes against me by quo- ting what I said with reférence to the “discovery” for which M. Clausius claims priority. «This formula was suggested to me by Mr. Joule, in a letter dated December 9, 1848, as probably a true expression for p, being required to reconcile the expression derived from Carnot’s theory (which I had communicated to him) for the heat evolved in terms of the work spent in the compression of a gas, with the hypothesis that the latter of these is exactly the mechanical equivalent of the former, which he had adopted in consequence of its being, at least approximately, verified by his own experi- ments. This, which will be called Mayer’s hypothesis, from its having been first assumed by Mayer, is also assumed by Clausius without any reason from experiment ; and an expression for pw, the same as the preceding, is consequently adopted by him as the foundation of his mathematical deductions from elementary reasoning regarding the motive power of heat*.” This passage is the sequel to the extract quoted by M. Clausius in his letter to you, and appeared in the same Part of the ‘Trans- actions,’ and in the same volume of the Philosophical Magazine. When it is read, I think it will be admitted that I did not do injustice to his claims in writing the following sentence two years * “On a Method of discovering experimentally the Relation between the Mechanical Work spent, and the Heat produced by the Compression of a Gaseous Fluid.” (Trans. Roy. Soc. Edinb. April vy, 1851; or Phil. Mag. December 1852.) 448 Mr. W. Swan on a new Method of observing later, of which the words “ Mr. Joule’s conjecture” have called forth his reclamation :— “A more convenient assumption has since been pointed to by Mr. Joule’s conjecture, that Carnot’s function is equal to the mechanical equivalent of the thermal unit divided by the tempe- rature by the air thermometer from its zero of expansion; an assumption which experiments on the thermal effects of air escaping through a porous plug, undertaken by him in conjunc- tion with myself for the purpose of testing it (Phil. Mag. October 1852), have shown to be not rigorously, but very approximatively true.” I remain, Gentlemen, Yours very faithfully, Witi1am THomson. LVII. On a new Method of observing the Spectra of Stars. By Witu1aM Swan, F.R.S.E* BOUT the beginning of March last, being engaged in ex- periments which involved observations of the dark lines in the solar spectrum, I attempted te observe the spectrum of Sirius; but the light of the star, enfeebled by two reflexions at the specula of a heliostat which formed part of my apparatus, and accompanied by a blaze of gas-light from the street lamps, was too faint to be visible. The failure of this experiment was so obviously due to the unfavourable nature of the trial, that I determined to renew it on the first opportunity. Although I was fully aware that Fraunhofer had observed dark lines in the spectra of several stars, I did not suppose that he had executed exact measurements, as no reference to such observations is made in his celebrated paper on the dark lines in the solar spectrum, where he describes the appearance of several stellar spectrat. I therefore resolved, as soon as I had leisure, to attempt a series of observations on the spectra of stars; and the recollection of a method of ascertaining refractive indices, described by me in 1844, immediately suggested an arrangement by which accurate results could be readily obtained ft. I have, however, more recently found that Fraunhofer actually measured the deviations of the rays in star-light ; and before de- scribing my own, I will shortly explain his mode of observation §. * Communicated by the Author. + Schumacher’s Astronomische Abhandlungen, 1823. { Edinb. New Phil. Journ., Jan. 1844. : re paper translated in Edinburgh Journal of Science, vol. viii. Pe fy 40a0- the Spectra of Stars. 449 A prism was mounted before the object-glass of a telescope furnished with a micrometer; and to this telescope a smaller one was attached, at such an angle, that one observer could view a star by direct vision, while another simultaneously observed its refracted image. The first observer made the star intersect the wires of the small telescope; the second brought the micrometer wire to intersect a line of the spectrum. The inclination of the optical axes of the telescopes being known, the deviation of the refracted rays was then readily found. The difficulty of measuring the deviation of the refracted light of a star, which arises from the apparent diurnal motion of the heavenly bodies, is completely overcome by this mode of obser- vation, but otherwise it is very inconvenient. Other methods of observation would be to refract the light in a vertical plane, and to observe so near the meridian that the star’s variation in alti- tude would be insensible; or to observe with an equatoreal tele- scope, refracting the light in the plane of the declination circle : but the first of these devices is obviously all but impracticable, and the second depends on difficult instrumental adjustments, while both involve corrections for atmospherical refraction. The method I have now to propose is perfectly free from all these objections. A prism is placed on a stage, furnished with proper adjusting screws, immediately behind the horizon-glass of a sextant or reflecting circle, and in the prolongation of the axis of the tele- scope through which the star is to be observed ; the whole being mounted on a suitable stand. The observer can thus see, at once, both the image of the star formed by rays which have been reflected at the mirrors of the sextant or reflecting circle, and the spectrum formed by rays which have passed through the prism, which has been adjusted to its position of minimum devia- tion. The image of the star being then made to coincide with any of the lines in its spectrum, the deviation of the rays is ob- tained directly, by reading off the angle indicated by the sextant or circle. I have had an apparatus constructed on this principle, but owing to unfavourable weather, I have as yet been able to make only one imperfect observation. This was on Mars, on the 16th of May. Notwithstanding the proximity of the planet to the moon, and the brightness of that luminary, then twelve days old, the spectrum was more brilliant than I anticipated. The sharp dise of the planet’s reflected image, as the tangent-screw was turned, glided on the edge of the spectrum like a bead along a thread; and contact could be made with the utmost nicety, the brightness of the reflected image being reduced to suit that of the spectrum. 450 Mr. J. J. Sylvester on Projectiles. It is perhaps unnecessary to point out the advantages of this mode of observation. These are the complete elimination of the effects of the star’s diurnal motion, and of refraction, advantages which it shares in common with Fraunhofer’s method. It pos- sesses, moreover, the additional recommendations of requiring only one observer, and of dispensing with the necessity of illu- minating either the field or the wires of the telescope. Those who have had any experience of the difficulty attending observa- tions of faint spectra will appreciate the value of this last pro- perty. 4 Duke Street, Edinburgh, May 17, 1856, LVIII. 4 Trifle on Projectiles. By J.J.Syvuvester, Professor of Mathematics at the Royal Military Academy*. JN teaching the subject of projectiles in vacuo, the following solution has presented itself to me of a question not wholly without practical interest, viz. of determining the angle of projec- tion to give the best range in the most general case, viz. when a gun is fired upon a slope at a given vertical height above the slope. The solution is not wholly either without theoretical interest in point of method, as leading to a result of some little complexity in maxima and minima by very simple calculations, and without the aid of the differential calculus. Therefore I venture to sub- mit it to the readers of the Philosophical Magazine. In the next Number of the Magazine I hope to have leisure to lay before them a subject of much greater interest, also belonging to the theory of projectiles, showmg how, by the oblique action of gravity combined with the earth’s rotation, a pendulum suit- ably adjusted may be caused to advance in a westerly direction, and so the earth be made the means of impelling a light carriage without any visible motive force, or any influence of magnetism. To this pendulum I give, for reasons which will be apparent when the matter is more clearly set forth, and in contradistine- tion to the ordinary fixed or circular pendulum on the one hand, and to Foucault’s free or spherical pendulum on the other, the name of the Cylindrical or Travelling Pendulum. But to resume the business of this present communication: let us begin with determining the angle of projection to give the maximum range when a gun is fired from a point im a plane sloping at an angle i from the horizon. This question is most simply solved (the result itself is of course familiar to all who will read this paper) by resolving the * Communicated by the Author. Mr. J. J. Sylvester on Projectiles. 451 velocity V, supposed to make an angle @ with the horizon, as also g, the accelerating force of gravity, each into two parts, , into V cos(@+7) and Vsin (8+%), and g into gsini and g cos?, respectively parallel and perpendicular to the plane of the slope. The time of flight is of course found by looking to the per- pendicular part of the velocity and of gravity alone, and is evi- V sin (0 +2) dently Odea which call 7; the range will evidently be Veosé.7 . boa a Sate See 9 be. ce (sin (2047) + sin i). Hence the best angle of range for this case is found by making 26+i=90, 0= ; (90—2). Now let us proceed to apply this result to the general case, as in the figure below, where BC is the slope upon which the range is to be measured, A the point of projection, AD the direction which gives the maximum range upon D the slope, and BC the actual ex- tent of this range; then I say AD is the direction which would give also the best range upon the slope AC. Since if, with the given ve- locity of projection, any other di- rection than AD would give a better range upon AC, the path corresponding to such direction must evidently cut BC at a point beyond C in that line in order to strike a point beyond C in the line AC. Hence if we draw the horizontal line AE, we know by the preceding case that the angle DAE= = CAB*. Let CAB=¢, which is to be found; also let AB=A/, and the inclination of BC to AD=z, 4 and being given; and let ¢= time of flight, then CAD=(90°—¢) + £ eg ote ( =90 —$). * This equation, and the isoscelism of the principal triangle of the figure to which it leads, would not readily present themselves to notice in the direct method of seeking the maximum range. It is for the sake of this pleasing geometrical relation, not unmixed perhaps with a desire of ex- hibiting the simple yet delicate turn of reasoning, the agreeable little point of method (a fly embalmed in amber) contained in the immediately pre- ceding paragraph, that I have thought this trifle worth preserving im the pages of the Magazine. ; 452 Mr. J. J. Sylvester on Projectiles. Hence also ADC=180—¢— (90° ) = 90°—§. Hence aes ue Pau sin ABC pony rat Shar ACB = Acost : ~ cos (¢+¢)’ and ¢ * _ Asin gd cost v C08 5 t=AD= ray ergy Hence eliminating ¢, we have va (eng) 1 _1l—cos¢d gheost (1+ cos) cos(e+¢) cos(¢+¢)" If .=0, i. e. if the gun is fired from the top of a battery com- manding a level plain, we have simply v sept diae which gives $ the double of the angle of elevation. In other cases we may make $+¢0=W, we have then 1— cos (r—z) ie 1 _sny sin ¢—cos t= Mea b cos cosy cosy gh Let a) (1+5) cott= cote; then ‘ sn ¢ . Fat ag Saray sin € cos (Yr—e) = ane or sin € cos (b+t—e)= ar from which ¢, the double of the angle of elevation, may be de- termined. Calling —— = cos p, and taking ¢,, d, as the two values of $, we have 26, +4—-€=p, 2o,++1—e=360—p. $,, $2 correspond to the angles of projection down and up the slope respectively, the one affording what in an algebraical sense is a maximum, and the other a minimum, but of course, arith- Dean and Wohler on Tellurium and Selenium Compounds. 453 metically speaking, both giving maximum values of the range ; the angle between them is 180—y. Thus when h=0, so that sine=0, w=90, and $,—¢, is a right angle, as may easily be verified. It may be worth while to exhibit the geometrical construction for the case of firing from a gun in position commanding a hori- zontal plane. Let A be the position of the gun, LN a portion of a circle to radius AL which represents the height of the gun above the plain, LM twice the height due to the velocity of projection, ANM a semicircle on AM, P the point in it bisecting the arc MN, then (abstraction made of the resistance of the air) AP is the elevation at which the gun must be pointed to give the greatest range on the plain below, for sec 2PAM obviously 1 (velocity of ball)? ip aL hl Suppose a sea battery as much as 300 feet above the water, and a cannon-ball projected at the low rate of 1200 feet per second (which is less than that of a common musket-ball), we should have twice the height due to the velocity of projection equal to 44720, and therefore 4.4720 sec 2a—= 7200 + 1 = 38,2666, and consequently 2a= 88° 30! 9" or a=44° 15! 5! differing very little from 45°; showing that certainly in a non- resisting medium, and in all probability in air, the height of the point of fire above the plane which it commands will very little indeed influence, under any conceivable circumstances of practice, the angle of elevation which gives the best range. U, The Common, Woolwich, April 30, 1856. LIX. Chemical Notices from Foreign Journals. By E. Arxinson, Ph.D. {Continued from p. 378. ] : i the January Number of Liebig’s Annalen, Dean and Wohler communicate the results of researches on tellurium and selenium compounds. By acting on sulphamylate of potash by 454. M. Stolzel on Artificial Ultramarine, telluride of potassium, a reddish-yellow oily body is obtained, The mode of its formation leads to the supposition that it is ¢el- luramyle, C!?H!! Te, but the analyses gave a result which agrees more closely with the composition of tellurbutyle, C?3H°Te. It is evidently an impure substance. It seems to act as a radical, and forms compounds with chlorine, iodine, bromine, and nitric acid, of which the latter alone is crystallizable. The oxide, ob- tained by digesting the chlorine compound with oxide of silver and water, is soluble im water, and is so strong an alkali that it liberates ammonia from chloride of ammonium. By acting on selenide of potassium with sulphomethylate of baryta, selenmethyle, C? H® S?, is formed. It is a reddish-yellow, very mobile liquid, of an extremely unpleasant odour. It is heayier than, and insoluble in water, It has more similarity in its reactions with sulphide of ethyle than with selenethyle, When acted on by nitric acid at a gentle heat, methyloselenious: acid, HO +C*? H®O, 2S8e0%, is produced. This acid crystallizes in groups of colourless prisms, and forms well-defined crystalline salts with ammonia, baryta, and silver, in which the water of the acid is substituted by one equivalent of the base. Heated with hydrochloric acid, chloromethyloselenious acid is formed. This has the formula HO + C? H® Cl, 2SeO*, It is readily obtained in crystals. Similar compounds with bromine and iodine were produced. M. Stélzel analysed several specimens of green and of blue ultramarine, and tried the action of various chemical reagents on them. The methods used in the analysis are also described. The results he arrived at may be given in his own summary of them. Blue ultramarine exhibited, under exclusion of the air, various degrees of resistance to fire; at a higher temperature it lost its colour, a mass being left behind which developed sulphurous acid on the addition of hydrochloric acid; blue ultramarine, pre- pared by igniting green, remained unchanged, and liberated sul- phuretted hydrogen on the addition of hydrochloric acid. Air, oxygen, chlorate of potash, saltpetre, sulphurous acid, and hy- drogen decompose the colour of both ultramarines at a high temperature, solid potash at a moderate heat, and strong acids and chlorine in the cold. When hydrogen is passed over blue ultramarine heated, sul- phuretted hydrogen is evolved; this is not the case with green ultramarine. Both leave, after this treatment, a grayish mass, which in the oxidizing flame of the blowpipe becomes first green and then blue. Solid potash and soda, and still more perceptibly potassium M. Briegleb on-the action of Phosphate of Soda on Fluor-spar. 455 and sodium, converted both ultramarines when gently heated into red ultramarine. Green ultramarines, when not acted upon by strong agents, had always a tendency to pass into blue. The same subject has been ably investigated by Breunlin, an abridgment of whose paper will appear in next month’s Magazine. With a view of obtaining an easy method for the preparation of fluoride of sodium, which might serve as a useful material for the preparation of fluorine compounds in general, Briegleb in- vestigated the action of phosphate of soda on fluor-spar. The two substances, mixed together in the proper proportions, were fused in a Hessian crucible, and the fused mass poured on an iron plate. The last parts poured out of the crucible were com- posed of a mass of small crystals. These were insoluble in water, and on examination were found to be apatite. This formation of apatite has been already observed by Manross. The fused mass was boiled with water for some time; some fluoride of sodium was obtained, but it bore no adequate proportion to the quantity that the theory required. An attempt to produce fluo- ride of potassium in this way gave still less favourable results. When, instead of extracting the fused mass with boiling water, it was digested with water on the water-bath for some days, and the liquid thus obtained filtered and evaporated, beautiful trans- parent octahedrons were obtained. These proved to be a double salt of phosphate of soda and fluoride of sodium,— 3NaO, PO®+ NaF + 24H0. This salt may also be obtained by digesting for several days ata moderate heat, finely powdered eryolite with a solution of phos- phate of soda and caustic soda. An attempt to produce potash and ammonia salts correspond- ing to the above gave negative results. A double salt of arseniate of soda and fluoride of sodium is obtained by fusing arseniate of soda and fluor-spar. To this, arseniate of soda is necessary; and it is better to combine its preparation with this reaction, by fusing together a mixture of nitrate of soda, arsenious acid, carbonate of soda, and fluor-spar. After maintaining the fusion some time, the mass is poured out and digested with water; the salt then dissolves up and may be easily crystallized. The crystalline form of this salt is exactly the same as that of the phosphoric acid compound. These salts may be considered to belong to the group of alums :— Al? 02 8802+ KO 802+24HO. Common alum, Na? 02 PO®+ Na FIl+24HO. New salt. Na? 0? AsO5+ Na F1+24HO. New salt. 456 M. Bertagnini on Salicyluric Acid. Bertagnini has made a series of experiments on the deportment of some organic acids in the animal organism. An abstract of the results appears in the February Number of Liebig’s Annalen. Crystallized camphorie acid, which is anhydrous, could be taken in doses of half a gramme without any ill effect. Upwards of 12 grms. were taken in the course of two days. The urine had a strongly acid reaction, from which ordinary camphoric acid was obtained. As this differs from erystallized eamphoric acid only in containing 2 equivalents of water more, the only change effected had been the assimilation of the water. Salicylic acid was taken in hourly doses of 25 centigrammes, till in the course of two days 6 grms. had been taken. On the second day a humming in the ears and sensation of numbness were perceived, The urine had, as usual, an acid reaction. Some unchanged salicylic acid was found in it, as well as a quantity of a new acid which contains nitrogen. Its formula is C!® H9 NO®, which is equal to salicylic acid and glycocoll, minus 2 equivs. of water :— C'* H® 0° + C4 H® NO*—2HO=C!8 HY NOS. Salicylie acid. Glycocoll. New acid. Salicylic acid appears hence to undergo the same change in pass- ing through the organism that benzoic and nitrobenzoic acids do. These are converted into hippuric and nitrohippuric acids ; the change being effected, as above, by the assimilation of gly- cocoll, with loss of 2 equivs. of water. The new acid has been named salicyluric acid. By boiling for several hours with fuming hydrochloric acid, salicyluric acid is decomposed into salicylic acid and glycocoll. It is a strong acid, and expels the carbonic acid from carbonates forming salts with the bases, which erystal- lize readily. It is probably bibasic. Anisic acid, taken to the extent of 6 grms., passed unchanged through the system and was obtained in the urine. It produced a feeling of heaviness in the stomach. Piria found that when salicine is treated with nitric acid of a mo- derate degree of strength, an acid which he named anilotinic acid was formed. According to the degree of concentration of theacid, various compounds, as helicine, nitrosalicylic, and picric acids, are obtained. From experiments which he made, Major considered that the anilotinic acid was identical with nitrosalicylic acid. This view is disputed by Piria, who finds that the formation of the acid depends less on the strength of the nitric acid used than on the presence of hyponitricacid. To prepare it, 1 part salicine with 8 parts nitric acid are placed in a well-stoppered vessel and put ina cool place. The nitric oxide generated cannot then escape, and causes the formation of hyponitric acid, which gives to the liquid M. Beedeker’s Analyses of Cow’s Milk. 457 a green colour. After some time, crystals of anilotinie acid separate. Salicine exposed to the action of nitric acid of the same strength in an open vessel is only converted into helicine. Anilotinic acid has the same composition as nitrosalicylic acid, HO,C** H4NO°, and the crystallized acid HO, C'* H* NO? +3HO. It has also great similarity in many of its properties. But it differs from nitrosalicylic acid in its solubility in boiling water, and in the salts which it forms with potash, ammonia, and silver. Neubauer has examined the volatile acid which occurs in the ~ fermentation of diabetic urine. He found that acetic was the only acid formed. Experiments which he made to procure the taurylic acid found by Stadeler in fresh normal urine, gave an unfavour- able result: phenylic and acetic acids were the only volatile acids which he obtained. Langenbeck and Stiadeler investigated the action of the copper salts of the fatty acids on the organism. They found that solu- tion of oxide of copper in fats, as well as the copper salts of fatty acids of high atomic weight, and especially of stearic and oleic acids, have an injurious action on the system, causing vomiting and diarrhoea; but that this action, even in large doses, is not fatal. The copper salts of volatile fatty acids act,on the other hand, as strong poisons, and their action is the more marked the lower the atomic weight of the acid. Acetate of copper has a very poisonous action, which is delayed, but not prevented by a quan- tity of admixed fats. Soluble copper salts are decomposed by solution of soap into insoluble stearate and oleate of copper; but in the organism this change is not sufficiently rapid to hinder the poisonous action. Solution of soap is nevertheless the most appropriate antidote, as the vomiting is not prevented, It is best to add to it a small quantity of oil, to prevent the injurious action of the soap on the mucous membrane of the stomach. Langenbeck and Stideler found that in these experiments the copper was more particularly found in the liver, whence it passes into the bile, and with this reaches the intestinal canal and is removed from the system. Boedeker made a series of analyses of cow’s milk taken at the various periods of the day in order. The times selected were the morning at 4 o’clock, noon at 12 o’clock, and evening at 7 o’clock. From these analyses, it appears that the increase of fat in the milk from morning to evening is so considerable that the total quantity of solid substances in the evening milk amounts to one-third more than in the morning milk. The quantity of buiter in the evening milk is more than double that of the morning, Phil. Mag. 8. 4, Vol. 11, No. 74, June 1856. 2H 458 M. Helkenkamp on two new double Salts of Cyanogen. The quantity of proteine substances, albumen, and caseine together, remains almost constant. The quantity of sugar of milk is greatest at midday, and decreases towards evening. The specific gravity of milk is no criterion of its value. A higher specific gravity may indeed be caused by sugar of milk and proteine substances; but a lower specific gravity does not necessarily arise from an increase in the quantity of butter, but also by a greater amount of water. The importance of this difference, not only for physiological chemistry, but also for dietetics and practical agriculture, is « obvious when we consider that a pound of the morning milk of the cow contains about 3 drachms of butter; a pound of the evening milk, on the contrary, 7 drachms. For the separation of nickel from iron, Schwarzenberg pro- poses a method founded on Herschel’s process; that is, to neu- tralize the dilute acid solution of the mixed oxides with carbon- ate of ammonia, and to precipitate the oxide of iron by boiling. Helkenkamp describes two new double salts of cyanogen with copper and ammonia. To hydrocyanic acid, a solution of hydrated oxide of copper in ammonia is added until the smell of the latter prevails. The mixture is then gently heated, and the addition of the ammoniacal copper solution is continued until the liquid, which at first was yellow, has become blue. After some time green rectangular lamine, possessing a splendid lustre, appear in the liquid. On analysis, these gave numbers corresponding to the formula 2Cu2 Cy + Cu Cy +2NH,+2HO. When these crystals are treated at a gentle heat with a mixture of ammonia and carbonate of ammonia, they dissolve into a blue liquid, from which, on cooling, lustrous blue lamin separate. These are distinguished from the former by containing 2 equivs. of water less. Their formula is 2Cu? Cy + Cu Cy + 2NH®. Fuchs had found, that burnt lime exposed to the air formed a compound of caustic lime with carbonate of lime. Wittstein’s experiments do not confirm this. He found that caustic lime which was exposed to the air, and from time to time powdered, increased regularly for forty months; on exposure for eight months after that time, no further increase was perceived. It consisted, then, deducting the impurities, of dry carbonate of lime. In a research which he had undertaken on the Influence of the Nitrates on Vegetation, M.’George Ville was led to seek a simple method of determining the nitrates. This he gives in the M. Ville on the Estimation of Nitrogen. 459 March Number of the Annales de Chimie et de Physique. When a solution of nitrate is mixed with excess of a solution of proto- chloride of iron and boiled, a portion of the iron is oxidized, and at the same time a mixture of deutoxide of nitrogen and hydro- chloric acid is disengaged. M. Ville found that when deutoxide of nitrogen, mixed with excess of hydrogen, was passed over spongy platinum heated to redness, the whole of the nitrogen is converted into ammonia, and this may be estimated by a stand- ard solution. This method is applicable even where the nitrate is mixed with considerable quantities of organic matter. It can be used for the determination of nitrates where the quantity of nitrogen does not exceed a centigramme; but when a larger quantity of nitrate is employed, losses are sustained which vitiate the results. Coke washed with hydrochloric acid and calcined in close vessels, Stenhouse’s platinized charcoal, and spongy iron may be substituted for the spongy platinum. If, instead of passing hydrogen and deutoxide of nitrogen over spongy platinum, deutoxide of nitrogen and sulphuretted hy- drogen be passed over soda-lime, the whole of the nitrogen is converted into ammonia, which is estimated as above. This method may be used for substances which contain a decigramme of nitrogen. The reaction on which the method depends is thus expressed :— 3HS + NO? + 2CaO = NH? + CaO SO? + CaS? or CaS +S. The execution of the method is simple, and does not take long, The protochloride of iron and nitrate are placed in a flask fur- nished with two tubes. Through one of these, which dips in the protochloride, a current of hydrogen passes which serves to expel all air from the apparatus. The other tube, by which the deutoxide of nitrogen and hydrochloric acid pass off, is connected with a second flask containing some potash which retains the hydrochloric acid. By means of two other tubes, the second flask is placed in connexion with an apparatus for generating sulphuretted hydrogen, and with the combustion tube. The combustion tube contains soda-lime, and affixed to it is a bulb apparatus for absorbing the ammonia. In making the analysis, hydrogen is first passed through the apparatus till all the air is expelled ; the combustion tube is then heated, and the current of hydrogen having been moderated, the flask containing the protochloride of iron and nitrate is gently heated. At the same time sulphuretted hydrogen is passed over, so that 3 or 4 centims. of the soda-lime may have become attacked at the time that the disengagement of deutoxide of nitrogen commences. After about ten minutes the action is complete: hydrogen is passed through, the apparatus for absorbing the ammonia is detached, and the ammonia estimated. 2H2 460 M. Béchamp on Pyroxyline. M. Ville describes a very convenient apparatus for obtaining a regular supply of hydrogen or sulphuretted hydrogen, which is a modification of Débereiner’s lamp. He points out, that in the fundamental reaction (that of protochloride of iron on a nitrate) a method of nitrogen determinations, similar im execu- tion and principle to that of Dumas, may be formed. The deutoxide of nitrogen is passed over copper-turnings, and the nitrogen estimated as such. But this is much less general and less certain than the others. In the same journal M. Béchamp has a paper on Pyroxy- line. He considers pyroxyline or gun-cotton as a compound of cellulose, in which 5 equivs. HO are replaced by 5 equivs. NO°: C*4 H170175NO%, and names it pentanitrocellulose. He had found before, that the action of ammoniacal gas gave rise to a new compound, ternitropyroayline, C? H'7O' 3NO°._ By the action of caustic potash on a solution in ether and alcohol of pyroxyline, he obtained an intermediate product, tetranitropyrozy- line, C22 H!7 0174NO05. These three nitro-compounds of cellu- lose differ not only in their definite composition, and in the cir- cumstances of their formation, but also in many of their proper- ties, as the action of solvents, that of reagents, and that of heat. The action of caustic potash on pyroxyline in the presence of water is different. The final product is in this case sugar. There are intermediate stages in the reaction, but they are not very distinctly marked. The quantity of sugar could not be ascer- tained, for a great part of it is decomposed into apoglucice and other acids. Sulphurous acid is without action on pyroxyline. Sulphuretted hydrogen acts, but the products formed are not definite. When pyroxyline is introduced into a strong solution of protocbloride of iron, the iron is peroxidized, all the nitrogen is evolved as deutoxide of nitrogen, and the cotton is reproduced, retaining its texture, and all its physical properties. The reaction may be thus written :— C* H!7 0'75N0°+30FeO + 3HO= 15Fe? 0? 4+ 5NO? Ete C4 HH? O79, From the reproduced cotton, gun-cotton was prepared. By treatment with sulphuric acid it was converted successively into dextrine and sugar. By the action of protochloride of iron, the primitive matter may be produced from the nitro-compounds formed by the action of nitric acid on starch, gum, mannite, and quercite, as well as from the nitric ethers in general. There are two distinct series of nitro-compounds ; that of which nitrobenzine and analogous bodies are the types, and that of Prof. Matteucer’s Kxperiments in Electro-physiology. 461 which pyroxyline isthe type. In the first, hydrogen is replaced by NO*; andin the last, HO is replaced by NO®. By the action of ferrous acetate on the first, all the nitrogen remains in the new body formed, as when nitrobenzole is converted into aniline. In the case of the second, the nitric acid is converted into am- monia. Béchamp points out that this reaction may serve as a method of determining ammonia, an idea in the execution of which he has been anticipated by M. Ville. M. de San Luca found that when about 7000 to 8000 litres of moist ozonized air were passed over potash, nitric acid could be distinctly detected. The air, before being ozonized, was freed _ from substances held in mechanical suspension, and from nitro- genized substances, by being passed through an apparatus con- taining potash and sulphuric acid. LX. Some Experiments in Electro-physiology. By Prof. Marrevcci. Jn a Letter to Dr. Farapay. My pear FRIEND, May 1, 1856. iT THINK I have already told you that for some time past I have been making experiments in electro-physiology. Allow me now to communicate to you the results of my work. I have lately succeeded in demonstrating and measuring the phenomenon which I have called muscular respiration. This respiration, which consists in the absorption of oxygen and the exhalation of carbonic acid and azote by living muscles, and of which I have determined the principal conditions and intensity compared with that of the general respiration of an animal, has been studied particularly on muscles in contraction. I have proved that this respiration increases considerably in the act of contraction, and have measured this increase. A muscle which contracts, absorbs, while in contraction,a much greater quantity of oxygen, and exhales a much greater quantity of carbonic acid and azote, than does the same muscle in a state of repose. A part of the carbonic acid exhales in the air, the muscle imbibes the other part, which puts a stop to successive respiration and produces asphywy of the muscle. ‘Thus a muscle soon ceases to contract under the influence of an electro-magnetic machine when it is enclosed in a small space of air: this cessa- tion takes place after a longer interval of time if the muscle is in the open air, and much more slowly stillif there be a solution of potash at the bottom of the recipient in which the muscle is suspended. Muscles which have been kept long in vacuum or in hydrogen are nevertheless capable, though in a less degree, of exhaling carbonic acid while in contraction ; this proves clearly 462 Prof. Matteucci’s Experiments in Electro-physiology. that the oxygen which furnishes the carbonic acid exists in the muscle in a state of combination. According to the theories of Joule, Thomson, &c., the chemical action which is transformed, or which gives rise to heat, is also represented by a certain quan- tity of vis viva, or by an equivalent of mechanical work. I have therefore been able to measure the theoretical work due to the oxygen consumed, taking the numbers which I had found for muscular respiration during contraction, and in consequence the quantity of heat developed by this chemical action, and finally this theoretical work according to the dynamical equivalent of heat. I have compared this number with that which expresses the real work which is obtained by measuring the weight which a muscle in contraction can raise to a certain height, and the number of contractions which a muscle can perform in a given time. It results from this comparison, that the first number is somewhat greater than the second, and the heat developed by contraction ought to be admitted among the causes of this slight difference: these two numbers are therefore sufficiently in ac- cordance with each other. I completed these researches by some new studies on induced contraction, that is to say, on the phenomenon of the irritation of a nerve in contact with a muscle in contraction. A great number of experiments lately made on the discharge of the tor- pedo, and on the analogy between this discharge and muscular contraction, have led me to establish the existence of an electrical discharge in the act of muscular contraction. The general con- clusion to be drawn from these researches is, therefore, that the chemical action which accompanies muscular contraction deve- lopes in living bodies, as in the pile or in a steam-engine, heat, electricity, and vis viva, according to the same mechanical laws. Allow me to describe to you briefly the only one of these ex- periments which can be repeated in a lecture, and which proves the principal fact of these researches, although it is limited to prove that muscles in contraction develope a greater quantity of carbonic acid than those in repose. Take two wide-mouthed glass phials of equal size, 100 or 120 cub. centims.; pour 10 cub. centims. of lime-water (eau de chaux) into each of these phials. Prepare ten frogs in the manner of Galvani, that is, reducing them to a piece of spinal marrow, thighs and legs without the claws, which are cut in order to avoid contact with the liquid in the phials. The cork of one of these phials is pro- vided with five hooks, either of copper or iron, on which five of the prepared frogs are fixed. Through the cork of the other phial are passed two iron wires, bent horizontally in the interior of the phial; the other five frogs are fixed by the spinal marrow to these wires. This preparation must be accomplished as rapidly On the Existence of Conics with a Curve of the Third Degree. 468 as possible, and both the phials be ready at the same instant, and great care taken to avoid the contact of the frogs with the sides of the phials or the liquid. When all is in readiness, with a pile of two or three elements of Grove, and with an electro-magnetic machine such as is employed for medical purposes, the five frogs suspended on the two iron wires are made to contract. After the lapse of five or six minutes, during which time the passage of the current has been interrupted at intervals in order to keep up the force of the contractions, agitate gently the liquid, with- draw the frogs, close rapidly the phials, and agitate the liquid again, You will then see that the lime-water contained in the phial in which the frogs were contracted is much whiter and more turbid than the same liquid contained in the other phial in which the frogs were left in repose. It is almost superfluous to add, that I made the complete analysis of the air in contact with the frogs according to the methods generally employed. Yours faithfully, A. Marrevcct. LXI. Note on an Intuitive Proof of the Existence of Twenty-seven Conics of closest Contact with a Curve of the Third Degree. By J. J. Sytvesrer, Professor of Mathematics at the Royal Military Academy*. ps general a conic can only be made to have five coincident points with a curve, and if the curve be of the third degree, the conic will of course cut it in a remaining sixth point; but at certain points of the cubic all these six points may come together. How many of these are there, and where are they? This question, which originated with Steiner, who stated the number, and sub- sequently treated by Pliicker, who assigned the position of the points, may be resolved by very simple considerations and without calculation. For if we can succeed in putting the characteristic of the curve (I mean what is commonly, but not altogether commodiously, called ‘“the-left-hand-side-of-the-equation-to-the- curve - when-the-right - hand-side - of -it-is-made-equal-to-zero”’) under the form wu? + v(uw +”), it is obvious that the conic ww-+ w? will intersect the cubic curve in the six coincident pomts 1?=0, o*=0. If now we take for our cubic the reduced form 2° +7°+ 25 +6mxyz, and make 7+ y+ 2mz=p, pxr+p*y+2mz= 4, p’2+pyt+2mz=r, it may be written under the form (1—8m®)z3+pqr, say —p2?+pqr ; or, if we please, under the form —p(z+ kp)? +p(qr + pk’p? + 8yk°p? + 8ykz"). * Communicated by the Author. 4.64. Royal Society :— And if we assume é properly, z+/p may be made to touch the multiplier of p, i.e. the multiplier may be made to take the form — plz + kp)? +p((2+kp)v+o?). From the symmetry which reigns between a and y, it is obvious @ priori that any value of k which is rightly assumed for the object in view will make w (when z is eliminated from it by means of the equation z+ 4p=0) a multiple either of e—y or #+Y3 the latter obviously cannot be true, since such values would make the given cubic a function of w+y and z; the proper values of k will therefore make «—y=0, from which, combined with the equation 223 + 2° + 6ma*z=0, the values of x: y: z may be deter- mined. ‘These will be three in number; and as we may write, instead of w and y, pz, py, or py, p2z, we obtain three sets of three points, corresponding to p being taken e+y+2mz; and consequently, by interchanging z with z and with y successively, we obtain altogether three systems of three sets of three points each ; any such factor as a+y-+2mz is a tangent to a point of inflexion, and it is clear @ priori that if the cubic is put under the form u3+v(ww +’), since v=0 make w2=0, v can only be a tangent at an inflexion. Hence the nine sets of three points just assigned are a// that can be found enjoying the property in question, and it is readily seen that e—y is the straight line containing the three points of intersection in which the second emanant, d d d\? 5 ten (2! a +y! ay +2! =) (e+y+2— 6mayz), at the point of inflexion [v+y=0, z=0] cuts the given cubic over and above the three coincident points 7+y=0, z=0. In other words, each ternary group of the twenty-seven points in question consists of the three points in which the curve is met by the tangents drawn from a point of inflexion, which agrees with the geometrical construction given by Plicker in Crelle’s Journal. Woolwich, May 3, 1856. LXII. Proceedings of Learned Societies. ROYAL SOCIETY. [Continued from p. 393. ] June 21, 1855.—The Lord Wrottesley, President, in the Chair. i ica following communication was read :— “On the ultimate arrangement of the Biliary Ducts, and on some other points in the Anatomy of the Liver of Vertebrate Animals.” By Lionel S. Beale, M.B. In his valuable communication to the Royal Society in 1833, Mr. Beale on the Anatomy of the Liver of Vertebrate Animals. 465 Mr. Kiernan describes and figures anastomoses between branches of the biliary ducts in the left triangular ligament of the human liver. The same author considered that the interlobular ducts ana- stomosed with each other, and communicated with a lobular biliary plexus, although he had never succeeded in injecting this plexus to the extent shown in his figure, neither had he directly observed the anastomoses between interlobular ducts. It must be borne in mind that these observations were made before the liver-cells had been described. Since the appearance of Mr. Kiernan’s paper, various hypothetical views have been advanced by different observers, with reference to the arrangement of the minute biliary ducts and the relation which the liver-cells bear to them. These points, however, have not yet been decided by actual observation. Miller considered that the ducts terminated in blind extremities. Weber showed that the right and left hepatic ducts anastomosed by the intervention of branches in the transverse fissure of the liver, which he described under the name of Vasa aberrantia. Krukenberg, Schréder Van der Kolk, Retzius, Theile, Backer, Leidy and others have adopted the view that the liver-cells lie within a network of basement membrane. On the other hand, Handfield Jones and Kolliker describe the liver-cells as forming a solid net- work, against the marginal cells of which Kolliker believes the ex- tremities of the ducts impinge, while Handfield Jones holds that the ducts terminate by blind extremities. Henle, Gerlach, Hyrtl and Natalis Guillot look upon the finest gall ducts as communicating with intercellular passages. Dr. Handfield Jones looks upon the small cells in the extremities of the ducts as the chief agents in the formation of bile, and to the liver-cells he assigns an office totally distinct from this. Busk and Huxley concur in this view, which would place the liver in the cate- gory of vascular glands, spleen, suprarenal capsules, &c. The observations of the author have been made upon the livers of several different animals examined under various circumstances. The results of the examination of injected preparations precisely accord with the observations made upon uninjected specimens some months before. The points which he hopes to establish are as follows :— 1. That the hepatic cells lie within an exceedingly delicate tubu- lar network of basement membrane. 2. That the smallest biliary ducts are directly continuous with this network. 3. That at the point where the excretory duct joins the tubes which contain the secreting cells, it is very much constricted, being many times narrower than the tube into which it becomes dilated. Lobules.—With reference to the nature of the lobules of the liver, the author offers some remarks. The only liver in which he has been able to detect distinct lobules, consisting of perfectly cir- cumscribed portions of hepatic structure and separated from each 4.66 Royal Society :— other by fibrous tissue, is that of the pig. In this liver each lobule has a distinct fibrous capsule of its own, and is separated from its neighbours by the branches of the vessels and duct for their supply. The lobules of the liver of other animals are not thus separated from each other, but the capillary network and the cell-containing network of one lobule are respectively connected with those of the adjacent lobules at certain points between the fissures in which the vessels and duct lie. In these livers there is not a trace of fibrous tissue between the lobules. The exceptional liver of the pig, with its distinct lobules, seems to bear in structural peculiarity the same relation to the livers of other animals, as the much-divided kidney of the porpoise bears to the more solid organ of most mammalian animals. In a physiological sense the livers of all vertebrate animals may be said to be composed of lobules; but in a strictly anatomical sense this term can only be used with reference to the liver of the pig, and, according to Miiller, that of the polar bear. The vessels and duct, at their entrance into the liver, are invested with much areolar tissue, which is continued for a considerable distance along the portal canals; but it gradually ceases as the vessels become smaller, and, with the exception of the liver of the pig above referred to, the lobules are not separated from each other by any areolar tissue, or by any fibrous tissue whatever, neither is any prolonged into their substance. Hence the investment of areolar tissue round the vessels in the portal canals of the liver seems to present no peculiar charac- ters in its distribution. It must be borne in mind, that in the exa- mination of uninjected specimens the small vessels and ducts are liable to be much stretched and torn in manipulation, and, in conse- quence, a striated appearance is produced which closely resembles fibrous tissue. Method of preparing specimens.—In order to demonstrate the arrangement of the ducts described by the author, it is absolutely necessary to harden the liver previously. This hardening may be effected by soaking a portion of the liver for some time in strong syrup, or in alcohol, and afterwards rendering the section trans- parent by soda. The mixture of alcohol and acetic acid recom- mended by Mr. L. Clarke in his investigations upon the spinal cord, has also been employed, as well as many other solutions which are not described. The fluid to which the author gives the preference is alcohol, to which a few drops of solution of soda have been added. Method of injecting the biliary ducts.—The following is the method by which, after numerous trials, the author succeeded in effecting this object. Lukewarm water is injected into the portal vein. After a time, when the liver has become fully distended, much bloody water will escape from the hepatic vein, but at the same time it will be remarked that bile escapes from the duct. This bile gradually becomes thinner, and at last nearly pure water flows from the duct, showing that the bile has been washed out. The Mr. Beale on the Anatomy of the Liver of Vertebrate Animals. 467 liver is now placed in soft cloths to soak up the water, and after some hours it will be found to have diminished much in volume, and to have a clayey consistence. The ducts are now empty, and may be injected with a carefully prepared prussian-blue injection, to which a little alcohol has been previously added. ‘The mixture is to be well stirred, and after having been carefully strained, it is slowly and cautiously injected into the duct. Plain clear size is next thrown into the portal vein, until the liver has become fully distended with it in every part. Lastly, a little plain size is in- jected into the duct, the vessels carefully tied, and the liver placed in cold water until the size has set, when very thin sections can be readily obtained with the aid of a sharp knife. The author has tried many other plans of injection, but the above has afforded the most satisfactory results. On one occasion a human liver was success- fully injected with four different colours; the portal vein with flake- white, the artery with vermilion, the duct with prussian blue, and the hepatic vein with lake. Evidence of the existence of a tubular basement membrane in which the liver-cells are contained. Not unfrequently liver-cells are set free with shreds of delicate membrane attached to them, and this can sometimes be seen to be prolonged either way in the form of a narrow tube. In certain specimens which have been exposed for some time to the action of dilute soda, the walls of the cells appear to be dis- solved and the tubes are seen to be occupied witk a highly refractive mass, and their outline is rendered very distinct. When portions of the cell-containing network are placed in strong syrup or glycerine, exosmose of the water occurs, the diameter of the tubes is much diminished, and their outline becomes distinct, but uneven, in consequence of the shrunken state of the tubes of the network. At the edge of a very thin section of liver stretching between two capillary vessels, a very thin membrane, recognizable only by the granular matter adhering to it, can sometimes be seen. The tubes of the network can be distended to a great extent by injection, so that the walls of contiguous tubes meet, while the capillary vessel between them becomes so compressed as not to be recognizable. The injection often forms a sharp line towards the capillary ves- sels on either side of the tube in which the cells lie, and gradually shades off towards the centre of the tube. The cells which escape into the surrounding fluid from injected specimens often have portions of injection adhering to them. If a section be made at right angles to the intralobular vein, the cells are seen to form lines radiating from the centre towards the circumference of the lobule, as authors have before described. These lines of cells are really tubes of basement membrane, com- municating with each other at intervals by narrow branches. In injected specimens the walls of the tube can be demonstrated, and are seen to be distinct from the capillary vessels. 468 Royal Society :— In the foetus, the cells are seen to be separated from the cavity of the vessels by two lines separated by a clear space. One of these lines is caused by the outline of the tube containing the cells, the other is that of the capillary wall. The author supposes that, originally, the liver is composed of a double network of tubes (cell-containing network and capillary net- work), the walls of which in most situations become incorporated, so that the secreting cells are only separated from the blood by one thin layer of basement membrane, which is very permeable to water in both directions, but the greatest force which can be applied with- out causing rupture is incapable of forcing bile through it. Of the contents of the tubular network of basement membrane, and of the arrangement of the cells within it. Within the tubular network lie the hepatic cells, with a certain quantity of granular matter and cell débris, and, in some instances, free oil-globules and granules of colouring matter. The cells are not arranged with any order or regularity. Some observers have endeavoured to show that the hepatic cells are arranged in a definite manner. Professor Lereboullet, one of the latest writers on this subject (1853), describes the cells as forming double rows. The two rows of cells may be separated by injection, and he gives two diagrams to illustrate their arrangement. The author has never seen anything like this in any liver which has been examined by him. In Mammalia, according to his observation, the cells are for the most part arranged in single rows (human subject, pig, dog, cat, rabbit, horse, seal, Guinea-pig and others), but in some situations two cells lie transversely across the tube, and they may be forced into this position by injection. The cells do not completely fill the tubes, and are not always placed quite close together, being sur- rounded with granular matter. Injection passes sometimes on one side of the tube, and sometimes upon the other; often it entirely surrounds a cell. In the human feetus and in the foetal calf there are two or three rows of cells within the tubes, and this is also the case in the livers of most adult reptiles and fishes which have fallen under the author’s observation, and in many parts of the network of the bird’s liver. Or tue Ducts of THE Liver. The duct, like the artery, lies close to the portal vein; usually this vessel is accompanied by one branch of the artery and duct, but not unfrequently there are two or three branches of these vessels with the vein. Anastomosis of the ducts near the trunk from which they come off.— The author observes that the anastomoses between the larger ducts and between the larger branches of the interlobular ducts are pretty numerous in the human liver, but these communications take place only near the origin of the trunks by means of intermediate branches. Different interlobular ducts do not anastomose with each other, but the branches resulting from the division of a small trunk are often connected together, Mr. Beale on the Anatomy of the Liver of Vertebrate Animals. 469 In some animals these communications are so numerous, that a complete network is formed at the portal aspect of the lobuie, or around a small branch of the portal vein. Not only are the right and left hepatic ducts connected together by intermediate branches in the transverse fissure of the liver, as E. H. Weber long ago demonstrated, but the branches coming off from these communicate with each other as well as with the trunks from which they come off. These branches are very numerous, and form an intimate network of irregular branched ducts. Similar communications occur between the branches in the portal canals, but they are not so numerous. This arrangement occurs to a less extent in the dog and in the calf, but it is not present in all animals. The author has not been able to demonstrate it in the pig, seal, rab- bit, horse, cat and monkey, although he is not prepared to say that, absolutely, no communications take place between the ducts near their origin, in these animals. Of the glands of the ducts.—The so-called glands are small cavi- ties of a rounded or oval form, or more or less branched, which com- municate with the cavity of the duct by a very constricted neck, The simple glands are for the most part situated in the coats of the ducts, so that, when injected, they scarcely project beyond the ex- ternal surface. These cavities or glands are most easily demon- strated in the pig. When a small duct from the human liver is laid open, two lines of orifices are seen opening upon the internal surface, as Kiernan described. The great majority of these, however, are not the open- ings of glands, but almost all of them are the orifices of branches of the duct which communicate with each other in its coats, or just at the point where they leave it. Very few of them are the openings of cecal cavities, which are very rare in the smaller ducts of the human subject. Vasa aberrantia.—There are many curious branches of communi- cation between the ducts in the transverse fissure of the liver, which have been well named “ vasa aberrantia” by Weber. Theile looks upon all these ducts as anastomosing mucus-glands. The author has seen these ducts in the portal canals, down to those not more than one-eighth of an inch in diameter. They present the same characters as the branches in the transverse fissure, but are not so numerous. ‘The coats of the vasa aberrantia are thinner than those of the ordinary ducts, and, like them, are lined with epithelium, principally of a subcolumnar form. These branches are always sur- rounded by areolar tissue, in which lymphatics are very numerous. The arrangement of the vessels about the vasa aberrantia is pecu- liar. The arteries and veins form a network, and each small branch of the artery lies between two branches of the vein, which com- municate with each other at frequent intervals by numerous trans- verse branches, some of which pass over and some under the artery. The author observes that this beautiful arrangement of the vessels occurs in the gall-bladder, in the transverse fissure, and in the portal canals. This disposition of the veins has the effect of ensuring free 470 Royal Society :— j circulation through them under different conditions, as when they are stretched or compressed. ‘The vasa aberrantia in the transverse fissure of the adult human liver are nearer to the branch of the portal vein than to the hepatic substance, and can be readily removed without any of the latter. A few small straight branches are sometimes observed to come off from the vasa aberrantia and to enter the hepatic substance. In the foetus, on the other hand, the vasa aberrantia are fewer in number, their course generally is more direct, they lie so close to the hepatic tissue that they cannot be removed unless a portion of the latter is taken away with them, and very many of the branches can be traced into the hepatic substance. The author regards the vasa aberrantia in the aduit liver in the light of altered secreting tubes, and believes that at one time they formed a part of the secreting structure of the liver. At the termi- nation of intrauterine life the portal vein increases in size, and the pressure thus produced may account for the gradual wasting and partial disappearance of the hepatic substance closely surrounding it. In the very thin edge of a horse’s liver, which consisted prin- cipally of areolar tissue, the gradual alteration of the ducts and ultimate complete disappearance of the secreting cells was traced. Upon the surface of the portal vein in the rabbit’s liver the trans- itional stages between the compact lobule of secreting structure and the branches of the vasa aberrantia have been well seen. Function of the glands and vasa aberrantia.—It has always been considered that the office of the ducts was to secrete the mucus of the bile, and a similar function was assigned to the vasa aberrantia by Theile. It seems to the author that a cavity communicating with a tube by a neck of less than ~J,;th of an inch in diameter, cannot be well adapted for pouring out a viscid, tenacious mucus. If these cavities contained mucus, the injection would not enter them so readily as it does, nor is it easy to conceive how the mucus poured out by these little glands would become thoroughly mixed with the bile as it passes qglong the ducts. Again, the bile of the pig, in which animal these glands are very abundant, does not con- tain more mucus than the bile of the rabbit, in which they are few in number and only found on the largest branches of the duct. ‘The vasa aberrantia do not possess any characters which, in the opinion of the author, justify the inference of their being mucus-glands. He regards the little cavities in the coats of the ducts (glands of the ducts) and the vasa aberrantia as reservoirs for containing bile, whilst it becomes inspissated and undergoes other changes. By these cavities in the ducts with thick walls, the bile is brought into close relation with the vessels which ramify so abundantly upon the external surface of the ducts. Of the finest branches of the duct, and of their connexion with the cell-containing network. Mammalia.—In well-injected preparations, the smallest branches of the duct can be readily traced up to the secreting cells of the Mr. Beale on the Anatomy of the Liver of Vertebrate Animals, 471 lobules. In most Mammalia, but not in the pig, a few of the finest branches of the duct can be followed for some distance beneath the surface of the lobule. These branches appear to lie amongst the secreting cells, but are not connected with them. They become continuous with tubes of the cell-containing network at a deeper part, while those secreting tubes nearer the surface of the lobule are connected with branches of the duct which do not penetrate. In many animals, particularly in the rabbit, and to a less extent in man and in the dog, the smallest branches of the duct are con- nected together so as to form a network, which is continuous with that in which the secreting cells lie. In the pig, the small ducts are, as it were, applied to the surface of the lobule; from these smaller branches come off, which pene- trate the lobule and are immediately connected with an intimate network, which lies partly in the capsule of the lobule itself. This network is continuous with, and may be looked upon as the most superficial portion of, the cell-containing network. In a perfectly normal state it contains only oil-globules and granular matter; but when the liver is fatty, it is found to contain liver-cells loaded with oil. From such a liver the author has a very beautiful preparation, in which the continuity of the very narrow duct with the wide tubes of the network, distended with large cells containing oil, can be well seen. ‘The duct and the tubes in which the secreting cells lie, both contain a little injection. The author has succeeded in demonstrating the communication between the ducts and cell-containing network in several mamma- lian animals, as well as in the human subject, by injecting the ducts in the manner described. Of these, the seal, hedgehog, rabbit and Guinea-pig have afforded the best specimens. In Birds, the continuity in injected specimens has been traced in the common fowl and in the turkey. The quantity of epithelium in the ducts of birds forms a great obstacle to the passage of the injec- tion, and from their extreme tenuity, the capillaries do not bear the preliminary injection of much water. Reptiles. —The author has seen the continuity between the ducts and cell-containing network, in an uninjected preparation of the newt’s liver, and in an injected liver of the adder. Fishes.—In consequence of the very fatty nature of the liver of fishes, it was found to be very difficult to harden it sufficiently to cut thin sections. The frequent presence of entozoa and their ova, renders it difficult to inject the ducts. The author succeeded in injecting the ducts and part of the cell-containing network in the sturgeon and in the Lophius, and in one instance, those of the very fatty liver of the cod. The continuity was also traced in an unin- jected liver of the common flounder. The injection often passes a certain distance into the finer ducts of fishes, but cannot be forced into the cell-containing network. In this way the appearance of blind terminations to the ducts is produced, as the continuity of the tube cannot be traced beyond the point at which the injection stops. 472 Royal Society :— The continuity of the finest ducts with the cell-containing net- work has been demonstrated in all classes of Vertebrata, both in in- jected and also in uninjected specimens. In all the livers of verte- brate animals which have been examined, the duct becomes much narrowed at the point where it joins the network in which the cells lie. The arrangement of the small ducts varies somewhat in dif- ferent animals. Sometimes a network of minute ducts is formed, which is continuous with that in which the cells lie, In other in- stances the communications between these terminal ducts are very few in number, or are altogether absent. Upon the latter point the author does not express himself positively, as he is sure that in the most perfect injection which he has been able to make, the whole of the numerous branches of the minute ducts have not been injected ; and from observations upon these specimens alone, he feels that only a very imperfect idea can be formed of their number or of their arrangement. Diameter of the ducts.—A table is given, showing the thickness of the coats of the ducts in different parts of their course. The walls of the smallest ducts are composed entirely of basement mem- brane, and are often not more than the ;J,>th of an inch in diame- ter in the uninjected state. In the pig, the diameter of the smallest ducts containing injection was about the z,5,th of an inch; in the 3000 human subject, about the =2,,th; in the seal, ,,5,th; and in some 5 fishes not more than the a, ath of an inch. It may be remarked, that this narrowing of the excretory duct, just before it becomes continuous with the secreting portion of the organ, is seen in the kidney and in other glands. Epithelium of the small ducts—The epithelium lining the small- est ducts presents very similar characters in different animals. The small cells are for the most part oval or circular in form ; sometimes they are angular, which probably results from pressure or stretch- ing of the ducts in the preparation of the specimen; sometimes the smallest ducts appear to be entirely filled with epithelium; in other instances the cells are very sparingly and irregularly scattered over the interior of the tube, while frequently no cells whatever can be distinguished. The author believes that, in a perfectly normal state, the minute ducts are lined by a single layer of delicate epithelial cells. This ductal epithelium does not pass gradually into the secreting epithelium, but ceases at the point where the latter begins. Hepa- tic cells are sometimes seen in tubes lined with this ductal epithe- lium, but probably their presence is the result of accident. In these cases the ducts are of course much stretched or dilated *. With reference to the relation of the ductal epithelium to the secreting cells of the liver, the author observes that a very similar arrangement occurs in the gastric glands. The secreting epithe- lium is alone found in the lower part of the gland (stomach tube), while the ductal portion of the gland is lined with columnar epi- thelium. * Mr. Wharton Jones has also seen hepatic cells in the small ducts.—Phil. Trans. Mr. Beale on the Anatomy of the Liver of Vertebrate Animals. 473 The secreting cells appear to occupy the entire cavity of the tube, and are not arranged in any order; so that the secretion, having escaped from the cells, must pass off towards the duct by the slight interstices between them. A similar disposition of the secreting epithelial cells occurs, but in a less remarkable degree, in some other glands; as the pancreas, lacteal, sebaceous, and sweat glands. The conclusions to which the author has arrived may be summed up as follows :— 1. That the liver of vertebrate animals essentially consists of two solid tubular networks mutually adapted to each other. One of these networks contains the liver-cells, and the other the blood. 2. The cell-containing network is continuous with the ducts. The small delicate epithelial cells lining the latter channels contrast remarkably with the large secreting cells, which are not arranged in any definite manner within the tubes of the network. 3. The duct is many times narrower than the tubular network at the point where it becomes continuous with it. 4. Injection passes sometimes on one, and sometimes on the other side of the tube, or between the cells, when two or more lie across the tube. Often, a cell becomes completely surrounded with in- jection. As injection can thus be made to pass readily from the ducts into the network and around the cells, it follows that there can be no obstacle to the passage of the bile along the same chan- nels in the opposite (its natural) direction. 5. Insome animals, the most minute ducts are directly connected with the tubes of the cell-containing network; of these branches, some pass amongst the most superficial meshes to join the network at a deeper part. In other animals the finest ducts first form a net- work which is continuous with that containing the liver-cells. 6. The interlobular ducts do not anastomose, but the branches coming off from the trunk are often connected with each other, as well as with the parent trunk, near their origin from it. 7. The walls of the smallest ducts are composed of basement membrane only. The thick complex coat of the larger ducts con- tains within it small cavities (the so-called glands of the ducts), by means of which the bile in these ducts would be brought into close proximity with the arteries, veins and lymphatics, which are very abundant wherever the ducts ramify. 8. The office of the vasa aberrantia, which are so numerous in the transverse fissure of the human liver and in the larger portal canals, appears to be similar to that of the cavities in the wails of the ducts. It is worthy of remark, that the network of vessels ramifying so abundantly in the coats of the gall-bladder, in the transverse fissure, and in the larger portal canals, are arranged ina similar manner, each branch of artery being accompanied by two branches of the vein. 9. The liver is therefore a true gland, consisting of a formative portion and a system of excretory ducts directly continuous with it. The secreting cells lie within a delicate tubular network of base- ment membrane, through the thin walls of which they draw from the blood the materials of their secretion. Phil. Mag. 8, 4. Vol. 11, No, 74. June 1856, 21 474 Royal Society :— «Report made to the President and Council of the Royal Society, of Experiments on the Friction of Discs revolving in Water.” By James Thomson, Esq., C.E., Belfast. [A Committee of the British Association for the Advancement of Science, consisting of James Thomson, Esq., C.E., and William Fairbairn, Esq., C.E., F.R.S., having been appointed “to make Experiments on the Friction of Discs revolving in water, with espe- cial reference to supplying data wanted in calculations relative to the action and efficiency of Turbine Water-Wheels in general, and of Centrifugal Pumps; and also to make an experimental inves- tigation relative to the action and efficiency of Centrifugal Pumps in general, and the amount of improvement derivable in them by the employment of an exterior whirlpool;’’ a sum of £50 from the Government Grant of 1853 was allotted by the Council of the Royal Society in aid of the inquiry. The experiments, as originally con- templated, have been arranged and conducted by Mr. Thomson, and the present Report of his progress is here inserted by order of the President and Council for the information of the Fellows. ] In last year’s Report of the Committee it was stated, that an appa- ratus for making experiments on the friction of discs revolving in water had been constructed, and that experiments had been com- menced with it. I have now further to state respecting the experi- ments for which that apparatus was adapted, that I have since got them completed and carefully arranged for the purpose of obtaining from them laws applicable for practical use. I now beg to lay before the Royal Society, as a brief statement of the most essential results, the following general equation to show the relation | etween the velocity of revolution of the disc, the dia- meter of the disc, and the mechanical work consumed in friction ;— ae yd? ‘ 90,000 in which d=diameter of the disc in feet, y=number of revolutions of the disc per minute, and z=number of foot-pounds of mechanical work consumed per minute. This equation is based on experiments naa range for the most part between the limits yd=192 and yd=5i8, and may be used with confidence, as sufficiently correct for most practical purposes, if the product of the number of revolutions per minute and the diameter of the disc in feet be between those limits. It is to be observed that the friction is slightly affected by the width of the water space within the case, and the coefficient 90,000 stated in the formula above is, for simplicity in the present brief report, taken between the coefficients obtained by two sets of experiments with different widths. A full report on the experiments already made, explaining the manner of conducting them and stating the detailed results, would be rather lengthened, and would require drawings and diagrams, for all of which I have carefully preserved the requi- site data; but before proceeding to put these in form suitable to be submitted to the Royal Society, 1 am desirous of prosecuting the Dr. Faraday’s Experimental Researches in Electricity. 475 remainder of the very interesting and important experiments which haye been entrusted to me,—that portion of the whole, namely, which relates especially to centrifugal pumps. I have also to state, that if my engagements permit, I should be desirous of proceeding with a renewed and more extended set of experiments on the fric- tion of discs, with an apparatus depending on the same leading principle as that which I have already used,—a principle which on trial has been found remarkably well suited for the desired purpose. For the attainment of greater accuracy and of a wider range of the experiments, it seems to me that no better method of procedure could be adopted, than to follow the same leading principles, with an apparatus of rather more refined construction, involving such improvements in details as have been suggested by the experience gained in the course of the experiments already made, and for the sake of greater steadiness of motion, worked by steam power instead of the hand of an operator. Should J have it in my power to con- duct this renewed set of experiments, a detailed account of them will be preferable to a detailed account of those already made. In respect to the experiments on Centrifugal Pumps, I have to say that I have prepared plans for an experimental apparatus on principles which | consider are peculiarly well suited for the attain- ment of useful and accurate results, and that I intend to proceed with the experiments as soon as my engagements shall permit. I have further to state, that from the Experimental Fund of £50 granted by the Royal Society, the entire outlay as yet incurred has been £6 5s. 9d., leaving a balance of £43 14s. 3d. for the more extended experiments yet remaining to be made. James THOMSON. Belfast, April 13, 1855. Noy. 22.—Sir Benjamin Brodie, Bart., V.P., in the Chair. The reading of Dr. Faraday’s paper, ‘“‘ Experimental Researches in Electricity—Thirtieth Series,’ was resumed and concluded. The following is an abstract :— * § 38. Constancy of differential magnecrystallic force in different media.—That a magnecrystal formed into a sphere (or some equiva- lent shape, so that mere length should have no influence) sets with the same force in the magnetic field, whatever the magnetic nature of the medium around it, has been shown generally, and for a few cases, on former occasions. The author was under the necessity of verifying and enlarging the old results; and upon employing the following magnecrystals, namely bismuth, tourmaline, carbonate of iron, red ferroprussiate of potassa, and also compressed bismuth, sur- rounded in succession by the following media,—phosphorus, alcohol, oil, camphine, water, air, and saturated solution of protosulphate of iron, he found the result to be the same as before. The mode of estimating the set was as follows :—The selected crystal being sus- pended in the magnetic field by a torsion-wire, right-handed force was then slowly applied by the revolutions of the torsion-head above, * Series XXIX. is published in the Phil. Trans. for 1852, p. 137. 21 476 Royal Society. until the crystal being gradually carried round, attained that position at which any additional torsion-force would cause it to advance sud- denly and considerably ; this position was called the upsetting point ; then left-handed torsion was put on until the like point was attained in the opposite side: the amount of the revolution of the torsion-index from one upsetting point to the other, minus the angle between the upsetting points, was considered as the measure of the set of the crystal under the constant magnetic force employed. As the setting force of a crystal remained constant for any sur- rounding medium, it was evidently possible to select a crystal and a medium such, that in one position the crystal would be attracted, and in another, at right angles to the first, be repelled in the same medium. ‘This case was realized with the paramagnetic red ferroprussiate of potassa and a solution of sulphate of iron, and also with the diamagnetic crystal carbonate of lime and diluted alcohol. A crystal was sought for amongst the ferrocarbonates of lime having this relation to the assumed natural zero presented by a vacuum or carbonic acid; but this case was not realized. § 39. Action of heat on magnecrystals—When magnecrystals, subjected to the same constant magnetic force, were raised or lowered to different temperatures, it was found that the setting force was affected; and at all temperatures from 0° F. upwards the force diminished as the temperature became higher. ‘Thus the torsion- force of a crystal of bismuth at 92° being 175, was at 279° dimi- nished to 82; that of a tourmaline, by passing from the tem- perature of 79° to 289°, was so far diminished ; that the power at the lower temperature was nearly double that at the higher. A like result occurred with carbonate of iron, and also with com- pressed bismuth. In all these cases the bodies resumed their first full power on returning to lower temperatures, nor was there any appearance of magnetic charge in any part of the range of observa- tions. Between 32° and 300° the force of bismuth appeared to alter by regular equal degrees ; but with tourmaline and carbonate of iron the change was greatest for an equal number of degrees at the lower temperatures. At a full red heat, however, both tourmaline and calcareous spar retained a portion of their magnecrystallic force or condition, and so did carbonate of iron up to that temperature at which it was decomposed. It is known that pure calcareous spar points with its optic axis equatorially, but that calcareous spar containing a trace of iron points with its optic axis axially. Calcareous spar retains its mag- netic characters at very high temperatures, but carbonate of iron and oxide of iron lose almost the whole of their magnetic force at a dull red heat. It was therefore expected that a ferrocarbonate of lime crystal might become absolutely reversed in condition by change of temperature, and this was found to be the case: at low temperatures the optic axis pointed axially, and at high temperatures equatorially ; and that through any number of changes, as the temperature of the crystal was alternately lowered and raised. § 40. Effect of heat upon the absolute magnetic force of bodies.— Geological Society. A777 Results were sought for, by which the magnetic force of bodies, already examined in the condition of magnecrystals, might be com- pared with the whole paramagnetic or diamagnetic force of the same bodies taken in the granular or amorphous state; but they were not satisfactory. The carbonate of iron gave the most distinct results ; and in its case the change of power by change of temperature was not the same for the two conditions. An examination of the three metals, iron, nickel, and cobalt, at temperatures between 0° and 300° F., gave a very interesting result, which the author is not aware has as yet been noticed. As the temperature rises, the force of the nickel diminishes, the force of the iron remains constant, the force of the cobalt increases; these facts suggest that there is a temperature at which the magnetic force is a maximum, and above or below which it diminishes. The order with the three bodies accords perfectly with that in which they lose the chief amount of their magnetic power, for much loss occurs with nickel at the tem- perature of boiling oil, with iron at a dull red heat, and with cobalt at a temperature near that of melting copper. GEOLOGICAL SOCIETY. [Continued from p. 398.] April 23, 1856.—Daniel Sharpe, Esq., President, in the Chair. Mr. G. Poulett Scrope, M.P., F.G.S., read a paper “On the Mode of Production of Volcanic Craters, and on the Nature of the Liquidity of Lavas.”’ The author referred to the two works published by him thirty years since, namely, ‘ On Volcanos’ in 1824, and ‘ On the Volcanic Formations of Central France’ in 1826; being desirous of calling attention to certain theoretical views developed in both, which were either controverted at the time or met by opposite theories, but which he believes the progress of inquiry has since tended to confirm. The first point insisted on is the formation of all volcanic cones and craters by the simple process observed in habitually active vol- canos, namely, the eruptive ejection of lavas and fragmentary matter from a volcanic vent; the accumulation of which around it cannot fail to give rise to the cone-shaped mountain so characteristic of a volcano, and to the crater usually contained in it. ‘lhe author showed, by the history of Vesuvius, that the cone of that moun- tain has, within the last hundred years, been at least five several times emptied by explosions of a paroxysmal character, and as often refilled by the products of subsequent minor eruptions; while throughout this time the exterior of the cone has been gradually increasing in bulk, and the old crater of Somma as gradually being filled up, by accretions from the volcanic matter ejected beyond the lip of the Vesuvian crater. He refuses to believe that any other process originally formed the outer cone and crater of Somma, than that which he and others have seen to be con- tinually augmenting the inner cone of Vesuvius, and which before his eyes in 1822 scooped out of its heart a crater concentric to that of Somma, three miles in circumference and some 2000 feet in depth. 478 Geological Society :— And generally of other great craters, ancient or modern, such as Palma, Santorini, the Val de Bove, &c., he considers that no argu- ment in favour of their having any other than a similarly ‘‘ eruptive” origin can be derived from the fact of their dimensions exceeding those of the crater of Vesuvius. The authentic accounts of enor- mous quantities of ejected pumice, scoriz, or ashes thrown out by many eruptions from Polynesian or American voleanos, reaching to distances of above a thousand miles, and of course spreading over the whole intermediate space, to a thickness sometimes of 10 or 12 feet at more than twenty-five miles from the volcano, would amply account for the dispersion, by explosive eruptions, of the contents of the largest craters ever observed. At the same time the author guards himself from being supposed to have ever denied that some amount of elevation has taken place in the external cone of a volcano through the occasional injection of lava from within into rents broken across its framework, and hard- ened into dykes, which may be called a process of gradual disten- sion. This, in fact, was suggested by him in 1824, All he con- tends against is the theory of Von Buch, that volcanic mountains are the result of the elevation of nearly horizontal beds of lava and conglomerates by some sudden expansion. He maintains, on the contrary, that the growth of a volcano by accretion, through erup- tive ejections on the exterior, and partial distension from within, is a gradual, though intermittent, normal process, which may be watched almost like the growth of a tree. The author next referred to the opinion published by him in 1824, that the liquidity of the stony and crystalline lavas (excluding the vitreous varieties) at the time of their protrusion, is owing, not to complete fusion, but to the entanglement between their com- ponent granular or crystalline particles of some fluid, chiefly water, at an intense heat of course, but unvaporized by reason of the ex- treme pressure to which they are subjected while beneath the earth, and escaping in vast bubbles of steam, when, by the opening of a fissure of escape, its discharge is permitted, and also by a kind of exudation through the pores and crevices of the expelled lavas as they cool. The author originally extended this theory of the combination of aqueous with igneous agency in lavas to all the crystalline plutonic rocks, which he considered to be derived from a mass existing beneath the crust of the globe under the above circumstances, in a state of extreme tension, such as on the occurrence of any sufficient local relaxation of the restraining pressure from above, or increase of tem- perature from within, must occasion its partial intumescence, and the consequent fracture and elevation of the overlying rocks, with or without extravasations of the intumescent crystalline matter through rents, in the form either of volcanic eruptions, or the protrusion of the granitoidal axes of mountain chains. These ideas on the character of the liquidity of lavas and the hy- pogene crystalline rocks, promulgated by the author in 1824-26, were considered unchemical at that time and little regarded. They have, however, of late been reproduced by M. Scheerer of Freiberg Binney on Foot-marks in the Millstone-grit of Tintwhistle. 479 and adopted by M. Elie de Beaumont, and have received much confirmation from recent researches into the conduct of water under pressure at high temperatures, its power of taking silex into solu- tion, &c. The author further asks the attention of geologists to the ideas developed by him in the same early works, and founded on actual and careful observations, as to the change of position occasioned in the component crystals of a matter moving in the pasty state here attributed to lavas and other plutonic rocks, during their emission or elevation under extreme pressure. He produced examples from the ribboned trachytes and pearlstones of Italy, Hungary, and Mexico. He considers gneiss to be granite elongated by a powerful lateral squeeze, probably at the time of its expulsion; and mica- schist to be the extreme result of the same action upon the lateral bands or selvages of the extruded mass or great dyke. This he thinks a more probable origin than the usual metamorphic theory of the melting and reconsolidation of sedimentary strata, though the one does not wholly exclude the other. At all events he considers the evidence presented in the peculiarities of texture, structure, and position of the laminated crystalline rocks to be conclusive as to their having been squeezed, flattened, and drawn out in the direction of their upcast, and attributes this process to the same elevatory movements which have thrust them up, and often forced them into wrinkled foldings on the grandest as well as on the most minute scale. To this same rearrangement of their crystalline plates or flakes under pressure he attributes also their lamellar cleavage. He refers to Mr. Sorby’s recent paper and experiments on slaty cleavage as confirming these views. The paper ends by recommending the more earnest study of the dynamics of geology, which has in this country been perhaps of late years somewhat neglected. May 7, 1856.—Daniel Sharpe, Esq., President, in the Chair. The following communications were read :— 1. ‘On some supposed Foot-marks in the Millstone-grit of Tint- whistle, Mottram en Longdendale, Cheshire.” By E. W. Binney, Esq., F.G.S. In a quarry in the lowest portion of the millstone-grit,—certainly 1000 feet down in that formation, and very near the underlying limestone-shale,—a series of five large impressions, lying in a straight line and nearly on the rise and dip of the strata, were met with. The strata dip towards 80° west of south at an angle of 12°. The dimen- sion of the impressions somewhat varies, but they are much of a size. Two of them, the longest, measure each 13 inches in length at their bottom, and 17 inches above; their breadth being respectively 4 and 3} inches at the bottom, and 8 and 9 inches above; their depth is about 3inches, ‘The distances between the impressions, measuring from the middle of one to the middle of another, is 2 feet 103 inches im every instance. ‘The impressions differ slightly in shape, but the bulk of the wet sand that had been originally displaced out of the holes was the same in each instance, whether the impressions were deep and short, or shallow and long; and the sand removed was 480 Geological Society :— forced up on the western side, and has the aspect of having been at least twice subjected to pressure ; as if one portion of the semifluid mass had been displaced, and another subsequently pushed partly over it, by successive footsteps. ‘The author supposes these impres- sions to have been made by the same kind of animal as that which gave rise to the foot-marks on the Permian sandstones of Corncockle Muir, and which has been termed Chelichnus by Sir W. Jardine. The Tintwhistle tracks are referable to a much larger animal than even the C. titan of Jardine, and Mr. Binney proposes to call it C. ingens. 2. “On the Lignite deposits of Bovey-Tracey, Devonshire.” By Dr. J. G. Croker. Communicated by the President. The author first described the physical features of the basin, sur- rounding the junction of the Teign and Bovey Rivers, in which these beds of lignite and their associated clays (used in pottery) are found. The lignite-beds come to the surface at Bovey Heath towards the north-western margin of the basin; they underlie towards the south- east about 11 inches in the fathom, and are covered by clays and gravels; their vertical thickness is about 100 feet. In the upper portion of the lignitic series are several (five and more) beds of loose lignite, covered and mixed with variously-coloured clays and granitic detritus ; a ferruginous sandy clay, 9 feet thick, succeeds, which is followed downwards by ten beds of ‘‘ good coal”’ or lignite, separated by bluish clay-beds and worked for fuel. Fir-cones, referable to the Scotch-fir (Pinus sylvestris), have been found in one of the uppermost layers of loose lignite. Large flabel- liform leaves also are represented by fragments 2 feet long and 20 inches wide in some of the higher beds, together with tangled masses of vegetable remains. In the second and fourth beds of good coal (the latter about 80 feet from the surface) the lignite abounds with the little seeds lately described as Folliculites minutulus by Dr. Hooker in the Society’s Quarterly Journal. The lignite gene- rally is composed of compressed coniferous wood, and retin-asphalte is locally abundant. The Bovey basin is about 60 feet above the sea-level, and was almost a swamp until it was drained within the last ninety years. A peat-deposit, in which fir-timber is found, covers the lignites towards the south. The author also referred to the extensive denudation that the district has undergone, and pointed to the Dartmoor granitic tract as the source of the clays of the lignitic deposits. He also noticed the several writers who have treated of the lignites and the geology of the neighbourhood. Lastly, Dr. Croker supplied some notes on the local occurrence of the numerous varieties of rocks and minerals in the vicinity of the Teign, such as ores of lead, manganese, and iron, also labradorite, schorl, &c., all of which, as well as the lignite and its vegetable remains, were illustrated by a large series of specimens. 3. “ Notice of some appearances observed on draining a Mere near Wretham Hall, Norfolk.” By C. J. F. Bunbury, Esq., F.G.S. About Wretham, six miles north of Thetford, are several meres, or small natural sheets of water, without any outlet. One of these, about 48 acres in extent, has been lately drained by machinery, for Mr. A. Dick’s Analysis of the Cleveland Iron Ore. 481 the purpose of obtaining the black peaty mud forming the bottom, and using it as manure. ‘This black mud is in parts above 20 feet in depth, and may be described as vegetable matter in a more com- plete state of deccmposition than ordinary peat. At a depth of about 15 feet in this peaty deposit occurs a distinct horizontal layer of compressed but undecayed moss, from 2 to 6 inches thick. ‘The moss is sufficiently well preserved to be recognized as the Hypnum fluitans, common in bogs and pools throughout the British Isles, and often growing in dense masses in shallow water. ‘The bed of moss is of considerable extent, though not occurring everywhere within the area of the mere. While wet and fresh it is of a bright rusty- red colour, and turns to a yellow-brown when dry. Numerous horns of the Red Deer were found in the peat above the moss-bed, and seldom at a greater depth than 5 or 6 feet from the surface; many of the antlers were of large size, and some appeared to have been cut with a saw. The black peaty mud beneath the moss is identical with the upper portion, and rests on a light grey sandy marl. No shells were observed; but trunks of trees, probably birch and oak, are found. Local seams of sand occur, and occasional stones of flint and quartz, resembling the gravel of the country. Numerous posts of oak-wood, shaped and pointed, were also found standing erect, and covered up by the peat. From the above facts it appears that, a great part of the upper peaty mud having been accumulated before the Red Deer became extinct in this part of England, the moss-bed must consequently have been formed at least some centuries ago ; and that, although the few mosses experimented upon by Dr. Lindley decomposed rapidly, yet the aquatic mosses, judging from the fossil bed of moss above described, are not rapidly destroyed by exposure to moisture, and that some other explanation must be sought for to account for the great want of Musci in the strata deposited in former geological periods. 4. “Analysis of the Cleveland Iron Ore.” By A. Dick, Esq., Metallurgical Laboratory, School of Mines. Communicated by Dr. Percy, F.G.S. The ore was weighed after drying at 100° C. Protoxide of iron Bi 39°92 Peroxide of iron.......- Seas Rehnaa ata 3°60 Protoxide of manganese......-.-++++- 0:95 Alumina ..-< sc ee cee teem cnr dracs 7°86 a a eee nee ee Magnesia.....--+ eee sr eeee resets 3°82 Potashie cs a steeds nee sts ore te ecw pistons, 0:27 Carbonic acid... ...- 00+ e eee rete 22°85 Phosphoric acid ......++-.ee-ssseeee 1°86 Silica, soluble in hydrochloric Acide ve tele Sulphuric acid.. ...--- +++. ++-- trace Bisulphide of iron (iron-pyrites) .....- O11 Water in combination ...:..+..-.:... 2°97 Organic matter ....-.-++++++: a isieias trace Residue, insoluble in hydrochloric acid.. 1°64 482 Royal Institution. Composition of the residue insoluble in hydrochloric acid:— — Silica, soluble in dilute caustic potash.... 0°98 Silica, insoluble in dilute caustic potash.. 0°52 Alumina with a trace of peroxide of iron.. 0°10 Titwupe ack, AvOUG «see has cee ke es US TMC sete wee eee erent cRe apie ote oe trace 1°63 The ore contains no metal precipitable by sulphuretted hydrogen from the hydrochloric acid solution. In the residue insoluble in hydrochloric acid, minute, bright, black crystals were detected, which were proved to contain titanium, and were supposed to be anatase. Prof. Miller of Cambridge has been able to measure certain of the angles, and found them to be identical with similar angles of anatase. The discovery of this mineral in the Cleveland ore is at least a point of considerable mine- ralogical interest, and may possibly furnish some additional indica- tion of the nature of the rock from which it was derived. The silica in the insoluble residue exists, it will have been ob- served, in two states, about two-thirds being soluble in dilute caustic potash, and one-third insoluble in that solvent. The rounded white particles, which, according to Bowerbank, have a truly oolitic or con- centric concretionary structure, are entirely formed of the soluble silica. The silica which existed in the hydrochloric acid solution was that which was present in a state of combination in the ore, probably with both protoxide and peroxide of iron; and the peculiar greenish- grey colour of the ore was doubtless due to the presence of this sili- cate of the mixed oxides of iron, just as the colour of the green par- ticles in the so-called greensand is believed to be due to the like cause. The proportion of phosphoric acid in the ore is comparatively large, and may be easily accounted for by the fossiliferous character of the ore. The quality of the iron smelted from this ore would cer- tainly be very sensibly affected by the proportion of phosphorus, and probably also by the silica existing in a state of combination. 5. “On the occurrence of Coal near the City of E-u in China.” By the Rey. R. H. Cobbold. Forwarded from the Foreign Office. The coal is worked by shafts and galleries in the hills near E-u, a third-class city, in the prefecture of King-hua, from which it is distant forty English miles by water. The pits are from 300 to 500 feet deep. The coal is bright, and not bituminous. KOYAL INSTITUTION OF GREAT BRITAIN. April 4, 1856.—‘‘ On the Measurement of the Chemical Action of Light.” By Henry E. Roscoe, Esq., B.A., Ph.D. No attempt has been made, up to the present time, accurately to measure the changes brought about in chemical substances by the action of the solar rays. The peculiar action of light on chemical bodies was first ob- served by Scheele on chloride of silver. Since that time the subject of the chemical action of light has attracted a large amount of attention, as the present perfection of the arts of the daguerreo- typist and photographer fully testify. Although we possess so Royal Institution. 483 many facts concerning the chemical action of light, this branch of science has only as yet arrived at that first or qualitative stage of development, through which every science must pass. The laws which regulate these phenomena are unknown to us, and we possess no means of accurately measuring the amount of the decomposition effected by the light. The speaker proceeded to describe the results of a series of experiments carried on by him in conjunction with Professor Bun- sen, which had for their object,— 1. Todeterminethe laws which regulate the chemicalaction of light; 2. To obtain a measure for the chemically active rays. When aqueous solutions of chlorine, bromine, or iodine are ex- posed (under certain conditions) to the direct solar rays they are decomposed, the corresponding hydracid being formed, and the oxy- gen of the water liberated. ‘The difference between the amounts of free chlorine, bromine, or iodine, contained in the liquid before and after exposure to light, gives the quantity of the substance decom- posed during the isolation. Now it was found that this quantity of chlorine, bromine, or iodine which disappeared, was not proportional to the time of exposure to the light ; in twice the time, for instance, less than twice as much substance was decomposed. The relation between the amount of light and the amount of decomposition was found in this case not to be a simple one. This anomalous action may be explained even from a theoretical point of view. Chemical affinity is the resultant of all the forces which come into play during the reaction ; hence it is not only the interchanging atoms which influence the result, but also those atoms which, without taking part in the decomposition, surround those actively engaged. The so-called catalytic phenomena show this action in a striking manner. To apply this general principle to the special case before us ; we have to begin with pure chlorine water ; after the first action of the light, however, hydrochloric acid is formed, hence the composition of the solution is altered, and a different result must be expected. This theoretical conclusion was verified by experiment. Chlorine water, to which 10 per cent. of hydrochloric acid was added, did not suffer any decomposition by an exposure of six hours to the direct sunlight ; during which time the same chlorine water, without previous addition of hydrochloric acid, lost nearly all the free chlorine which it contained *. In order then to obtain a true measure of the action of light on any chemical substance, it is necessary that the body formed by the decomposition should be removed from the sphere of action. This cannot be done with chlorine water; a new sensitive substance was therefore employed. Equal volumes of chlorine and hydrogen gases when exposed to the direct sun-light unite with explosion; in diffuse light, the action proceeds gradually. In presence of water the hydrochloric acid formed by the combination is immediately absorbed, and thus with- drawn from the sphere of action, and the diminution of the volume of the mixed gases arising from this absorption gives an exact mea- * Poggendorff’s Annalen, xevi, 373; and Quarterly Journal of Chemical Society, Oct. 18595, 484 Intelligence and Miscellaneous Articles. sure of the amount of action effected by the light. The diminution in volume of the gas measured by the rise of water in a graduated tube was found to be regular, proving that when the light is constant the amount of action is directly proportional to the time of exposure. The relation between the amount of action and the amount of light was experimentally determined, by allowing known quantities of diffuse light to fall upon the sensitive gas. Experiments thus conducted showed that the amount of aciion is directly proportional to the amount or intensity of the light. These simple relations were observed by Dr. Draper, of New York, in 1848, but his method of experimenting differed essentially from that employed in these researches, and was not susceptible of any very great degree of accuracy. ‘The relation between the amount of action and the mass of the sensitive gas has not as yet been fully determined ; experi- ment has however already shown that the relation is not a simple one. Many very interesting phenomena were observed in the course of these investigations. When the gas is first exposed to the light no action whatever is observed; after a short time the absorption slowly begins, and increases until a maximum has been attained, after which it proceeds regularly. This phenomenon of induction probably depends on a peculiar allotropic change which the chlorine must undergo before it is capable of uniting with the hydrogen. The speaker concluded by expressing his intention of continu- ing these experiments at Heidelberg, in order exactly to determine the relation which exists between the amount of action and the volume of gas employed; to investigate the phenomenon of induction; and to obtain, if possible, an absolute measure for the chemical rays. LXIII. Intelligence and Miscellaneous Articles. ON SOME OF THE PRINCIPAL CAUSES OF ATMOSPHERIC ELECTRICITY. BY M. BECQUEREL. fHXHE causes which constantly furnish the air with an excess of positive and the earth with an excess of negative electricity, excesses which are capable of giving rise to storms and other phe- nomena under certain conditions, are still unknown, notwithstand- ing the endeavours of physicists to discover them. In studying this question some years ago I observed the electrical effects produced in the tissues of plants, and at the contact of these plants with the soil; in this contact the soil is constantly positive and the plant negative, whatever may be the part of the plant put in metallic communication with it. I then indicated this evolution of electricity as one of the causes of the electricity of the atmosphere. In repeating these experiments a year ago, I was struck by the anomalies manifested, in operating on the margin of a river, or in the river itself, or at a certain distance, near the plant, and I was thus led to study the electrical effects produced at the contact of the soil with a fall or stream of water, of which I then understood all the importance. In last October I communicated to the Academy the first results of my experiments, and I have since been constantly occupied with this question, which leads us to one of the principal sources of atmospheric electricity,—a question of a most compli- Intelligence and Miscellaneous Articles. 485 cated nature, from the numerous causes which conduce to the general effect. The apparatus employed in these researches consists of—1l. dia- phragms of porous porcelain, or little bags of sail-cloth, each con- taining a depolarized plate of gold or platinum, surrounded by charcoal of sugar-candy, with a view to rendering the electrical effects constant during a few moments in order to measure them ; 2. tangent compasses of great delicacy, adapted for experiments of this nature ; 3. atmospheric electrometers destined to the collection of the electricity of vapours formed above the soil or the water; and 4. various accessories,—amongst others conducting wires of copper, gold and platinum covered with gutta percha, &c. I have said that the electrical effects produced by the contact of the soil and water are complex, for they vary in direction and inten- sity according to the substances which compose the soil, or which are dissolved in the water; for the production of electrical effects, it is necessary that there should be a heterogeneity between the water of the river and that by which the soil is moistened. When the waters are slightly alkaline they are negative; when they are acid, as is the case with the earth of heaths, they are positive. The well- waters of Paris often present effects of this kind, in consequence of the infiltration of drainage waters, which change in nature from time to time; thus in the course of a month the electrical effects are seen to change in intensity and sign, without any derangement of the apparatus. From this state of things it results that sometimes there are no electrical effects, as is also the case in experimenting with the water of a river and its sandy banks, or the adjacent lands which are washed during inundations. It is necessary to establish per- manent observations to follow all the variations to which the actions of contact are subject, and to be on one’s guard against the effects of polarization, which are always to be found in operating only fora few moments. Very commonly the polarization is destroyed in the course of twenty-four hours, and the effects of which we are in search may then be observed. In some exceptional cases the elec- trical current has sufficient intensity to cause the action of a needle telegraph at a distance of several kilometres. When water evaporates, either from a stream or from the earth, it must necessarily carry off with it an excess of electricity of the same nature possessed by the one or the other, and this becomes diffused in the atmosphere ; this electricity may arise not only from the reaction of the water of the river upon that with which the soil is moistened, but also from the decomposition of organic matter. In the latter case the electricity is always positive, whether it arises from the river or from the soil; in the former the two vapours are of contrary signs; the effects are complex. From the foregoing it will be understood why storms generally take place in summer, at that period of the year when the decom- pesition of organic matters and evaporation are at their maximum, and also why they are so frequent and so violent under the tropics at the period when the sun approaches the zenith. ‘This is so true, that in those regions there is always a storm bursting at each instant in a locality suitably placed in relation to the sun. 486 Intelligence and Miscellaneous Articles. The phenomena to which I have just referred are so varied, that it is indispensable, before formulating general principles, to multiply experiments in a place serving as a permanent observatory, then in flat countries and amongst mountains, on the margins of rivers and water-courses, and on the sea-shore, in countries like Holland, where there are large alluvial tracts, in salt-marshes, &c. Then, and then only shall we be able to judge of the importance of the subject with which I am occupied, and which is connected with one of the greatest questions in terrestrial physics.—Comptes Rendus, April 14, 1856, p. 661. ON THE BORONATROCALCITE OF SOUTH AMERICA. BY C. RAMMELSBERG. This mineral has lately been frequently referred to. It forms larger or smaller roundish lumps, coated with a yellowish-gray earth, and consisting internally of an aggregation of fine silky needles, amongst which yellowishcrystals of Glauberite (NaO, 80°+CaO,SO*) sometimes occur. In other respects the substance is quite pure and homogeneous. The powder dissolves with difficulty in boiling water, and the solution has an alkaline reaction. It is soluble in acids, even in the cold. Analyses gave,— Chloride of sodium...... Si hy Sulphate of soda ...... 0°41 Sulphate of lime..... .. 0°39 Boracie seid’ o? fe, SR VA BS =e" 48°70 Dairies 0h DE ORS S eee 12°61 13°13 SOUR ee Le eee IPO aU 6°67 Rotashe ose ee Be oe 0°80 0°83 WALTERS yh PORE Fe F440 35°67 As the oxygen of the soda (potash) and lime =1 : 2, and that of the acid is equal to that of the water, and nine times that of the lime, the mineral consists of 1 atom soda, 2 atoms lime, 6 atoms boracic acid, and 18 atoms water, and must be regarded as a com- pound of 1 atom of bicarbonate of soda, 2 atoms of biborate of lime, and 18 atoms of water. The formula NaO, 2B0°+42(CaO, 2B0°)+18HO requires— 6 atoms boracic acid = 2617°2 = 45°63 2 atoms lime...... ne Mess i= eee o igtom) soday. wae a to kay Mw Stay] 18 atoms water.... = 2025°0 = 35°32 5735°2 100°00 The properties of this mineral agree with the description given by Hayes; but his analyses led him to the formula CaO, 2B05+6HO, which is that of borocalcite. arlier analyses by Ulex and Dick gave less simple formule.—Poggendorft’s Annalen, vol. xevii. p. 802. ON A COPROLITIC DEPOSIT IN BOHEMIA. BY PROF. REUSS*, Prof. Reuss of Prague communicated to the Vienna Imperial Academy of Sciences, November 9, 1855, a note on Fossil Excre- ments of Fishes in the bituminous marl-slate of the Old Red Sand- * Communicated by Count Marschell. Meteorological Observations. 487 stone near Ober-Langenau, Bohemia. ‘These coprolites are richer in organic matter (sometimes as much as 74°03 per cent.) than any other at present known. ‘Treated with ether, they give a rather considerable quantity of a greasy liquid matter, of disagreeable smell. Other coprolites have in the course of time been deprived of a large proportion of their organic matter by decomposition, or by mecha- nical agents; those, however, under notice have suffered but little alteration in quantity and quality, owing probably to the circum- stance that they have been quickly enveloped with inorganic matter, andin this way secured from the action of water and air. Every one of these coprolites is surrounded with a concretion of magnesian limestone, segregated from the imbedding rock. These concretions likewise contain nitrogenous organic matter, sometimes to the amount of 36°56 per cent. This matter may be supposed to have originated from the decomposition of numerous fishes, the remains of which are frequently found preserved in the concretions. This considerable deposit of organic matter, besides its scientific interest, may acquire a practical importance. It would be perhaps profitable to use these slates for the production of gas, paraffine, &c., and to use for manure the residuum of these operations, containing a notable proportion of potash and phosphoric acid. METEOROLOGICAL OBSERVATIONS FOR APRIL 1856. Chiswick.—April 1, 2. Exceedingly fine. 3. Overcast: rain. 4. Densely clouded : fine, with low white clouds. 5. Fine: cloudy. 6. Fine: frosty at night. 7. Fine: cloudy: rain. 8. Rain. 9. Cloudy: rain. 10. Rain. 11. Fine: showery: rain at night. 12. Rain: cloudy and mild: fine. 13. Fine: cloudy: hazy. 14. Fine: rain: boisterous, with rain at night. 15. Overcast: cold north- east wind. 16. Fine, but cold: masses of white clouds. 17. Dusky white clouds: fine: cloudy. 18. Overcast: fine: cloudy. 19. Overcast: densely clouded: clear: frosty. 20. Fine: frosty at night. 21. Cloudless: very fine: hazy at night. 22. Overcast: cloudy: frosty. 23. Slight haze: cloudy. 24. Uniform haze: overcast: fine. 25. Foggy: very fine: rain. 26. Heavy rain: cloudy. 27. Rain. 28. Clear: fine: frosty. 29. Partially overcast: cloudy and cold. 30. Fine. Mean temperature of the month ......... fay weno fer, Seen secs 46°48 Mean temperature of April 1855 ...........ssceccsssscescasgences 46 08 Mean temperature of April for the last thirty years fasebeside 47 +13 Average amount of rain in April ...........seesscessceesnereoeere 1°553 inch. Boston.—April 1. Fine: raine.m. 2. Cloudy. 3. Cloudy: rain PM. 4. Cloudy. 5. Fine. 6. Cloudy: rainp.m. 7. Cloudy. 8. Cloudy: rainp.m. 9. Cloudy. 10. Cloudy: rain p.m. 11. Fine: raine.m. 12. Rain a.m. and p.m. 13. Fine. 14. Cloudy. 15. Fine. 16—19. Cloudy. 20. Fine. 21—24. Cloudy. 25. Fine. 26. Rain a.m. and p.m. 27. Cloudy. 28. Cloudy: rain r.m. 29. Cloudy: rain A.M. and p.m. 30. Cloudy. Sandwick Manse, Orkney.—April 1—3. Bright a.m.: cloudy p.m. 4. Cloudy, drops A.M. : clear, aurorap.M. 5. Cloudy, drops a.m.: clearr.m. 6. Damp A.M.: clear e.m. 7. Bright a.M.: dropsp.m. 8—10. Cloudy a.m. and p.m. 11. Showers, cloudy a.m.: clear p.m. 12—14. Cloudy a.m.andp.m. 15. Cloudy a.m.: clear, fine p.m. 16. Cloudy a.m. and p.m. 17. Showers, cloudy a.m.: cloudy p.m. 18. Showers, cloudy a.m.: clear, fine p.m. 19. Clear a.m.: drizzle p.m. 20—22. Cloudy a.m. and p.m, 23. Clear a.m.: cloudy p.m. 24. Cloudy a.m.: cloudy, fine p.m. 25. Cloudy, fine a.m.: cloudy, drops p.m. 26. Clear a.m.: hail- showers P.M. 27. Hail-showers a.m.: sleet-showers p.m. 28. Sleet-showers A.M. and p.m. 29. Sleet-showers A.m.: cloudy p.m. 30. Bright a.m. : cloudy p.m. Mean temperature of April for previous twenty-nine years ... 43°:47 Mean temperature of this month ...-..++ susvevecvsbuscuescaterte 44 +56 Mean temperature of April 1855 ....0c.ccssececsssesessvensecenes 43 +20 Average quantity of rain in April for fifteen previous years... 1°90 inch. The drought is quite unprecedented, only ‘68 of rain haying fallen for two months, vE.o | 98.1 | 26.4 gt.zb SL.g¢ | og jov.vé |9S.g5 | zLL.6z bbl.6z 9£.6z £19.62 SgL.6c | -uvayy ss-srcpash or, | Zo. | eon | mir] “ant ig’. D Ly i Lbs 62 P 25 £6.6z “| gg.6z gz.6z o19.6z ££9.6z ‘of Se cates “mi| ane “heeth b Soh rE oS gg.6z - gl.6z 17.62 39.67 org.6e | -6z m_ leu ob fb F obl. 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"GO, | casa | ems | tas | Seb | fb 6b) Se | €S bb.6z ov.6z $6.32 £g1.6z 097.62 °g “or. | Fo. ‘as | «m | ems | Seb | tb gr} 6£ | 65 9f.6z 1¥.6z o1.6z gbt.6z £64.62 cr stesreseeslaneterees) “ogg | og | agg ib} -Se | 6b Ze | ZS gt.6z b£.62 16.gz gbz.6z of £.6z 9 ger Geseeteesleaacetsetiasag. | os 5 ab) Lb zbl-ov | LS of.6z of.6z gz.6z gil.6z 368.6 > @ = Seppe paraiso 66 | SLb OS le of | 65 $6.62 67.67 $2.62 $50.62 £LL.6¢ v ; "£0. |. 61. [Stas |. soe] sms |S Sb Seb 1” oSlo bh | $5 1.62 gv.6z LE.6z 999.62 Ezg.6c € é ZO, To. | 2 “Seca 528 5 A e- = Z Ss ieee HLS Pe 2 gee gh -aecad . ‘oqeq 1855. z a8 *19J9UIOU0Z) SACYON *19}9U1010ZH s,uIaquoyIS | |} | | o Sse 0 Oe ee ome sO Leet Once Se ee wees) Be dba Be (pm wale oe see. 9 oe Seer wT SL a Shue e 6 *1a}9U10U0ZQ SIPHON ; *LaJVUIOUOZY) - 8 UIaquaqos ee CSIs Foams nann ee oe ee ek a ee ne a ene ee ae ee Oe Pe ee ee ee ee ee ee ee [S| 522 Dr. Barker on the relative value of the Table (continued). j ) j TOTAL Be\28 BE/ 23 BSl/o8) . [eeles S |Ss\88] 8. |28|/88] 8S |48\88] 3° |S8tRe 2o| 9 BO |S a6 "Ss eal 1856 1856. 1856 1854 Bod Feb, 6.| 3| 7 ||Apras.| 0| 2 |/May1o.| 3] 4 |) D&: OB Tae + Te we 11.| 0} 3 || 1855. 14.; 4] 4 6.| 0} 4 12.| 0O| 1 || January; 10} 20 18.} 1 4 S| OE). 2 18.| 4 | 5 || Febuary) 22] 36 19.} 2| 3 9.| 0| 3 19.| 4| 6 || March | 19]. 46 eet ot 1a! BaD. sk 29.| 0 | 2 || April...) 19] 43 10 | 19 15.| 6| 6 93.1 0| 3 || May ...| 34| 93 Mae Lee 168 24 24.| 0) 3 June...) 26] 68 Sigeastt 2 17.| 1] 4 96.| 0 | 4 |\July ...| 19] 42 ae 18.) 0| 5 98.| 0 | 3 || August | 22] 43 3 23.| 0| 2] 30.| 0| 5 ||Sept....| 21) 41 7| 2 7 26. 0| 3 31.| 3 | 6 ||October| 31| 56 vs | ig tute 27.|. 2) 5 ——|—|] Nov. ...| 24]. 38 i 3 98. 2| 3 14 | 64 || Dee. ...] 28] 47 24.| 9 | 1 eatece S| dl epee 5.1 91 1 pare 50! | January} 30) 41 26.; 0} 2 Febuary; 1 Dy Ae te | May ry 4 Z March 5| 37 29.} o| 2 Peat ee April...) 13] 50 30.1 o| 1 Rol | My wf 14} 64 —|— ali ep Extitosaal 5 | 37 9.} 0! 5 | 351 | 793 — el | ke BIST i | A few brief remarks may serve to indicate the importance of the results thus obtained. During the eighteen months over which the observations ex- tended, there were 122 days in which Schénbein’s paper indicated the presence of ozone; while there were 207 days in which Moffat’s papers were discoloured. In other words, in 85 days, out of 207, Schénbein’s papers failed to record the action of ozone! On the other hand, Moffat’s papers never failed to receive a tinge when Sch6nbein’s indicated ozone. It is true, on one occasion (October 31st, 1855) Schénbein’s papers were more deeply tinged than Moffat? s; but this may safely be passed over as a mere accident, when weighed against the contrary results of 197 observations. The total amount of ozone indicated by Schdnbein’s paper , during the entire period of observation, is represented by the number 351, while Moffat’s paper registered 793. The mean monthly amount by Schénbein’s was 19:50; by Moffat’s 44-05. ie, } Ozonometers of Drs. Schénbein and Moffat. 523 F ae mean daily amount by Schénbein’s was 1:70; by Moffat’s 83. Such results are too plain to require any lengthened com- ments on the relative value of the two ozonometers. There can no longer remain a doubt that the papers prepared by Moffat’s formula are more sensitive than those of Schénbein in the ratio of 2°3 to 1:0. The advantages possessed by the former have been proved by observations in other localities besides Bedford. Mr. Glaisher, in his valuable report on the “ Meteorology of London and its relation to the Epidemic of Cholera,” has stated that “the papers prepared by Dr. Moffat were more sensitive than those of Dr. Schénbein, and accord- ingly indicated the presence of ozone when none was indicated by those of Schénbein ” (page 71). It appears clear, therefore, that our first step to be taken in further observations on ozone is to adopt without delay, and uniformly, Dr. Moffat’s formula for test-paper*. The next step must be, not to theorize on scanty data of coincidences, but to extend, as widely as possible, the field of observation, and carefully to record results. Our progress may seem slow, but it is by such patient labours that the secrets of nature’s laboratory must be disclosed. In conclusion, we would express a hope that meteorologists who have not yet added the ozonometer to their observatories will no longer delay to do so. It must be by the cooperation of many that certain and great results will be attained. Hach may feel that he is doing little—that he is only collecting, from day to day, a few grains of evidence. 2 Wae'esy “Trahit quodcunque potest, atque addit acervo Quem struit, ......... 2 But slight exertions become important when regarded as con- tributions to a great result. Thus we must go on from day to day, from year to year; and, by and bye, the properties of ozone will be wrested, like other secrets, from nature. We shall then be able to contrast the certainties known with the hints and suspicions of our present stage of inquiry, even as now we may contrast our certain knowledge of heat, of electricity, of magnet- ism, of light, and of many chemical phenomena, with the mere forebodings of a period not yet very remote. Bedford, June 2nd, 1856. * As considerable care is required in the thorough saturation of the paper with solution of iodide of potassium and starch, we would suggest to ob- servers desirous of obtaining trustworthy results, that it would be most advisable to obtain the prepared paper from the accredited agents, Negretti and Zambra, Hatton Garden, London. This may be done at a very reason- able expense. 2M2 [ Baa J LXVI. On the Law of Electric Discharge. By Dr. P. Riess. To the Editors of the Philosophical Magazine and Journal. GENTLEMEN, N the May Number of your Magazine there is a paper of twenty pages, entitled “ On a General Law of Electric Dis- charge, by Sir W. Snow Harris,” which would necessitate many observations if all the errors contained in it were to be corrected. As, however, this paper possesses rather a personal than a scientific interest, I will confine myself to a very few remarks, which may easily be added to by those familiar with the subject. The appearance of the above paper is not to be laid to my charge. M. De la Rive, in his most recent English work, has given in part to my investigations upon electrical heat that con- sideration which they have long enjoyed in German works, and has not made use of Harris’s labours upon the same subject. That Sir W. Harris should gladly give importance to his own re- searches is of course very natural; but whether he has done it in a proper manner others may judge. For my own part I have only to observe, that it does not appear. to me to be altogether just that he should make me answerable for statements which are not derived from my original works, that he should ascribe to me “a systematic disparagement” of his scientific labours, and lastly, that he should allow himself (p. 359 at the bottom) to express a suspicion regarding me. Against the two first pro- ceedings I hereby remonstrate, and his suspicion L beg to say is totally unwarranted. The subject which, according to the title, forms the principal contents of the paper is easily dispatched, perhaps to the satis- faction of the author. He has long since set up a law upon the dependence of the electrical heat upon the charge of the battery. T ascertained this law to be incorrect, and set another in its place. Sir William Harris now seeks to bring the two laws into agreement by the inadmissible process of giving a signifi- cation to the symbol s in my formula ar different from that given to it by me. He understands by it the resistance in the circuit, although in the formula (which constitutes only a portion of the general heat-formula) this ought not at all to be intro- duced, as it is supposed to be constant. If the resistance in the circuit is variable, not only this, but also the resistance in the battery is expressed, which must have entirely escaped Sir W. Harris, as he asserts (p. 3854) that I had overlooked the latter resistance. The question for him therefore is a simple one, whether the formula referred to with the signification which I attached to the symbol s be correct or false, and he may endea- Dr. P. Riess on the Law of Electric Discharge. 525 vour to ascertain the latter by experiment. But most certainly experiments must be justified by theory, and exactly performed and described if any weight is to be attached to them. Far more irksome to me than this explanation, is the discus- sion of the other portion of the memoir which consists of the frequently-repeated but unjustified assertion that my own in- vestigations on heat, by which, at the expense of much time and trouble, I have arrived at simple laws, are nothing more than mere reproductions of the author’s previous experiments. It is quite true, and has been acknowledged by me, that his un- satisfactory and inconclusive experiments were the cause of my investigations, which were rewarded with a better result. But the credit of having opened up an investigation, although it is by no means small, rarely satisfies those who led the way ; they require more, even though they should only acquire it in the eyes of those who are unacquainted with the subject. “It is a course by no means uncommon in the history of physical science.” Sir William Harris had made a great many electrical ex- periments, and from them, without possessing the necessary knowledge, had deduced numerous results which always re- mained unintelligible to me, as they were often in contradic- tion to well-known facts, and even with the experiments of the author himself. I was not aware that any one, either here or in England, had found these results more intelligible than I had done. Of course, now that my endeavours of many years have made known the laws of electrical heat, some experiments out of this mass have become more comprehensible, but it is certain that even these experiments, cancelled by other contra- dictory ones, would never have rendered the discovery of these laws possible. Nothing remained for me to do, in the state- ment of my investigations, except to bring the existence of these experiments to the knowledge of the reader, and then, on my own account, to place the subject, which had been confused in the highest degree, in a clear light. My first memoir on electric heat (1837) commences with the mention of Harris’s most recent work, a memoir which the author often quotes, and in which he had summed up his previous observations*. As besides elec- trical heat other phenomena are investigated in this memoir, I gave a complete abstract of it in Dove’s Repertorium der Physik, Berlin, 1888, and described the instruments and ex- periments mentioned therein as exactly as the statements of the author enabled me to do. All the results of this memoir which I considered as correct I have since made use of under the name of the author with suitable acknowledgments. * “ On some Elementary Laws of Electricity,” Phil. Trans. 1834, 526 Dr. P. Riess on the Law of Electric Discharge. In my investigations of heat, it was natural that I should submit the instruments and processes employed by the author to a rigid criticism, and reject them when they did not stand the test. It is not true that I ascribed the unsuccessful ex- periments of Sir W. Harris to the faulty arrangement of his thermometer. My words, that the experiments were not made with the necessary care (Pogg. Annalen, vol. xl. p. 835), cannot be referred to the thermometer, as immediately afterwards, in the description of my instrument, I say that the bulb (con- sequently the most essential portion) was arranged according to Harris’s description. A greater simplicity and sensibility of the thermometer certainly appeared to me to be desirable. My objections, if my memory is correct after so long a time, referred to the totally inadmissible process of the author of effecting the discharge of the battery by means of a ball which was obliged to shatter a glass dise lying upon the battery. I was compelled at once to reject the “ unit-jar” of Sir W. Harris, as I perceived that during the charging the unit of the amount of electricity would continually decrease, and that the more rapidly the smaller the charged battery is. I adopted another method of measuring the amount of electricity, because it was justified by theory and proved by practice, and in employing it I did not forget to state that it was described by Haldane in 1800. I have hitherto supposed that I was the first to make a practical use of this process, but I am now informed by Sir W. Harris that it had already been employed by him in 1830. My error is very excusable, for it was difficult to believe that a physicist should have been acquainted with a correct method of measure- ment, and have rejected it in favour of an mcorrect one. I have sufficiently acknowledged the-merits of Sir W. Harris in the improvement of the electrical thermometer, by frequently de- scribing and once figuring it in the form which he represents as the most perfect. But I must affirm that he is still unacquainted with the use of the thermometer in the demonstration of the laws of electrical heat, as he is still unaware of the necessity of employing a calculation to render the data capable of com- parison when the wires are changed in the thermometer. Nor can I at all agree with Sir W. Harris in his favourite idea, that his thermometer is a peculiar instrument essentially different from Kinnersley’s. The disadvantageous vertical position of the tube with the fluid is common to both struments. The air-holder is globular in the one and cylindrical im the other ; in the one the wire is extended by the fastening of its two ends, in the other it is fastened to the lid of the air-holder, stretched by a weight and lowered into the air-holder. These are differ- ences of construction which may perhaps affect the convenience Mr. A, H. Church on the Production of Formic Aither. 527 and exactitude of the experiments, but cannot constitute an essential difference in the instruments. My claims to the right of invention appear to be much stronger than those of Sir W. Harris, for I have introduced changes into the electroscope of Behrens and Fechner of a much more important nature than those made by him in Kirmersley’s thermometer, but never entertained a thought of describing the improved electroscope as a new instrument. Lastly, I have to remark, that the author’s assertion that Kinnersley only employed his thermometer for the illustration of the mechanical force of the electrical explosion in the air is completely destitute of foundation. In 1761 Kinnersley also made use of his thermometer to test the amount of heat which the discharge of a Leyden jar “ produced in a strip of wet writing-paper, a wet flaxen and woollen thread, a blade of green grass, a filament of green wood, a fine silver thread, a very small brass wire and a strip of gilt paper.” It is inconceivable that Sir W. Harris did not know this, not because it stands in one of my memoirs to which he has referred, but because these experiments are mentioned in a classical English work, Frank- lin’s immortal ‘ Experiments and Observations,’ which is cer- tainly the best known and most widely diffused of all the works that have ever been written on electricity. I have the honour to be, Gentlemen, Your obedient Servant, Berlin, May 19, 1856. P. Riess. LXVII. Note on the Production of Formic Aither. By Axtuur H. Cuurcu, F.C.S.* XALOVINIC acid, C® H®OS%, experiences under certain conditions a metamorphosis of considerable interest. Just as oxalic acid, when heated with pumice-stone, with sand, or, as recently pointed out by Berthelot, with glycerine, yields formic and carbonic acids, as expressed by the followmg equation,— C4 H? 0? =C? H? 04+ 2C0?, so oxalovinic acid, when similarly treated, yields formiate of zethyle aud carbonic acid, thus :— CHS. .,C4H®.,, tie Coa OP =C? ~ 0*+4+2C0?. Oxalovinic acid, even in the impure state in which it occurs when prepared from its potash salt by the addition of an equiva- lent quantity of sulphuric acid, furnishes, when heated with gly- * Communicated by the Author. 528 M. E. Breunlin on the Constitution of cerine at 100° C., so large a quantity of formic ether as to be an excellent source of that substance.. The greater part of the oxalovinie acid which I employed m my experiments was. pre- pared by the action of pure hydrate of potassa upon oxalic ether, using equivalents of the two bodies; yet on testing a mixture of absolute alcohol and dry oxalic acid left in contact since June 1854, the presence of a considerable amount of the acid oxalate of zethyle was indicated ; and the fluid part of this mixture, treated with an equal volume of glycerine, yielded on distillation about ‘ one-fourth its weight of formic sether. The formiate of ethyle produced in the manner above deseribed agreed in odour, boiling-poit, and specific gravity, with the formic ether obtained by the ordinary methods; but in order to satisfy myself of its identity, I burnt a portion of the body with oxide of copper in the usual manner; the following are the de- tails of the analysis :— 0:2015 srm. of substance gave 0°36 grm. carbonie acid, and 0°14525 grm. water. The theoretical and experimental per-centages of carbon and hydrogen in formic ether are as follows :— Theory. Experiment. Carbon . . . 48°68 48°7 Hydrogen 3. oe 80 From the results of some qualitative experiments, I think I am justified in concluding that formiate of methyle may be pro- duced from oxalo-methylic acid by the action of glycerme; and that it would not be without interest to examine the behaviour with glycerine of the other members of that series of bibasic acids to which oxalic acid belongs, not indeed only the acids, but the acid zethyle and methyle compounds. LXVIII. On the Constitution of Green and Blue Ultramarine. By E. Breunuin of Weissenau*. NE of the most beautiful and important mineral colours is that called ultramarine. Although we have long known it, and it is now produced in large quantities and is extensively applied, its true constitution has never been clearly ascertained. The theories hitherto proposed have been grounded on the mode of its preparation, and on a few analyses, but none of them has obtained authority; they are not precise, and prove httle by means of numbers; perhaps also the materials used for the | analysis were faulty. * Translated by Dr. FE. Atkinson from the Annalen der Chemie und Pharmacie for March 1856. Green and Blue Ultramarine: 529 From the increasing production of ultramarime, and its im- portance in trade and industry, it appeared interesting to explain by chemical analysis the nature of the blue compound; and by the kindness of one of the most celebrated ultramarme makers in Germany, I obtained very beautiful samples of ultramarine, blue as well as green. Porcelain clay, or a similarly constituted artificial silicate, is mixed with soda and sulphur, and ignited without access of air until the mass has caked together ; it is then ground and washed. The resulting powder is either agai ignited with soda and sul- phur, or gently heated with access of air; the blue colour then appears. i The different sorts of blue ultramarine exhibit different phy- sical properties, while their chemical relations are the same. The colour varies from a delicate czerulean to a fiery dark blue with a tinge of red. The lighter sorts form a compact, dense powder ; the darker kinds are looser and velvety. Green ultra- marine has no fiery colour; its shades vary from apple-green to blue-green. Ultramarine is not moistened by water, but it is by alcohol, even greatly diluted. When treated with water, some sulphate of lime is dissolved ; but neither a sulphite, hyposulphite, nor a sulphide can he detected in the solution. ulphuretted hydrogen is evolved when ultramarine is treated _ with acids; even with dilute acetic acid the colour disappears more or less rapidly. The most beautiful shades are the soonest decomposed. Many ultramarines resist the action of acids more energetically than others ; the green are the easiest decomposed. If strong hydrochloric acid im excess be poured on ultra- marine, an odour is evolved which irritates the eyes, similar to that observed in the preparation of polysulphuretted hydrogen when polysulphide of calcium is treated with excess of strong acid. When ultramarine is decomposed by acid, a whitish gelatinous fluid is obtained, which does not filter clearly. The cloudiness arises from finely divided sulphur; it is more decided in the blue than in the green ultramarine, and shows the presence of a higher sulphide which is present in ultramarine, and contributes essentially to the colour. Sulphur, clay, and silica remain on the filter ; the filtrate contains the clilorides of aluminium, iron, and sodium, and sulphate of Jime. When strongly ignited im air, both ultramarines lose their colour, which becomes first dull and dirty, and then quite disap- pears. If green ultramarine be heated with pentasulphide of sodium, and the mass washed out and gently heated in the air, it becomes blue. The reason of this change will be found in the different constitution of blue and green ultramarine, 530 M. E. Breunlin on the Constitution of I made analyses of five kinds of blue ultramarine (I. to V.), and of two kinds of green (VI. VII.), with the following results :— - LF Il. Ill. IV. V. VI. VIL. Silica . . . 874 40°9 35:5 363 366 384 388 Alumina . . 380°0 242 284 259 25:0 27-4 283 Oxide ofiron . 13 O58 O6 31 O9 O68 O9 Soda... 149 163 192 21:0 17:2 16:9 13:9 Sodium. 5 :606+2°B <4 8:2. <1*9ree Bd » S Bienen h:3i 25Gb Sulphur 4s ofp PBOn05 8D ooh: Bis5- det BA > a i 54 eae Rates anion a e 2 j / . /\ a ‘ @ Lids.y oo ‘ . Phul Mag. Ser. #. VoL Z/. PLIL ® J Basire Je, . — = —— _ — 4 t . oo ®. ~ — LhilMag. Sex PVol 1 PLL Fig 15a ve ne 3 - ae ig 16 3 <4 x B Bc AB : Y DUE le \/ aX i, MOR aP. V i” ely (i) i Mag. Sev.4.Vol.1L. PL IL. J Basie se. i Wie ware ; eh