THE JOURNAL OP THE ROYAL INSTITUTION OP GREAT BRITAIN. CONTENTS. Page On the Formation of an Artificial Compound Dispersive Power in a Compound Lens, for correcting the Front Lens of a Refract- ing Telescope. By PETER BARLOW, F.R.S., Cor. Mem. Inst France, &c. . . . . . • I' On those Birds which exhibit the Typical Perfection of the Family of Anatidae. By WILLIAM SWAINSON, Esq. F.R.S., L.S., &c. 1 1 On the Relation between the Polyhedral and Spheroidal Theories of Crystallization ; and the Connexion of the latter with the Experiments of Professor Mitscherlich. By J. F. DANIELL, F.R.S., Professor of Chemistry in King's College, London . 30 On the Illumination of Theatres. By A. AINGER, Esq. . .45 On the Red Solutions of Manganese. By THOMAS J. PEARSALL, Chemical Assistant in the Royal Institution . .49 On the Comparison of British, French, and Dutch Weights. By Dr. G. Moll, Professor in the University of Utrecht. [Com- municated by the Author] . . . . .64 I. On a Remarkable Case of Coryza Phlegmatica. II. On the direct Formation of Oxide of Iodine and lodous Acid. III. On Nitrogen in Natural Waters. By the CAVALIERS LUIGI SEMENTINI, of Naples, M.R.I., &c., in a Letter addressed to the Secretary of the Royal Institution . . .75 On the Direction of the Radicle and Germen during the Vegetation of Seeds. By THOMAS ANDREW KNIGHT, Esq., F.R.S , Pre- sident of the Horticultural Society, &c. . . .80 On Disinfection and the Practice of Quarantine ; with some Re- marks and Communications relative to Contagious Disease, and especially the Cholera. By ANDREW URE, M.D., F.R.S. , &c. &c. 83 U CONTENTS. Page On the Penetrativeness of Fluids. By J. K. Mitchell, M.D., Lecturer on Medical Chemistry in the Philadelphia Medical Institute . . . . . . .101 Proceedings of the Royal Institution of Great Britain . ; .119 Proceedings of the Royal Academy of Sciences of Paris . 133 Miscellaneous Scientific Proceedings on the Continent . .171 FOREIGN AND MISCELLANEOUS INTELLIGENCE. § I.— MECHANICAL SCIENCE. 1. Parabolic Ridges formed on moving Water . . . 176 2. New Theory of Capillary Action . . . . 177 3. On the applicable Force exerted by a Horse . . . ibid. 4. Bevan on the relative Hardness of Road Materials . . ibid. 5. On the Bur of Perforations (R.W. Fox, Esq.) . . .179 6. Condensation of Mercury by Pressure . • . ibid. 7. Instrument for the Condensation of Water by the Pressure exerted by Water at great depths of the Ocean (Invented by Professor Par- rot of Dorpat) . . . . . .180 8. Comparison of the Prussian Weights and Measures with the new English Weights and Measures (Professor Eytelwein) . ibid. $ II.— CHEMICAL SCIENCE. 1. On the Electro-Magnetic Effects of Metallic Plates having various Posi- tions, Intervals, &c. &c. (M. Bigiou) ... 181 2. Hare's Delicate Galvanometer ..... ibid. 3. Powerful Electro-Magnet (Professor Henry and Dr. Ten Eyck) 182 4. On Electricity induced by the Red and Violet Rays of the Solar Spectrum ...... ibid. 5. On the Identity of the Nervous and Electric Fluids . .183 6. Singular Electrical Effect . . . . 184 7. Explosion of Phosphorus and Nitric Acid . . . ibid. 8. On the Phosphorescence of certain Substances . . 18& CONTENTS 111 Page 9. On Oxalic Acid (M. Gay Lussac) '. / .,* . . 186 10. Dr. Turner on the Volatility of Oxalic Acid . ".«.., • *bid. 11. Scintillation of Steel. Inflammation of Gunpowder .. . 187 1 2. New Pyrophorus . ,W . "'!''< . .,•-.' 188 13. Crystallization of Oxides of Iron and Zinc (M. Haldat) . . ibid. 14. Discovery of Vanadium in Scotland • • ... 189 15. Yellow Dye from Sulphuret of Cadmium ~ V ' . • ibid. 16. Separation of Antimony and Tin . . -.» - . 190 17. Compound of Bi-cyanide of Mercury and Iodine of Potassium (Dr. Apjohn) . • . . . . . ibid. 18. Composition of Tartaric Acid . ... 191 19. Racemic Acid, or Para-tartaric Acid .... ibid. 20. On Gallic Acid (M. Braconnot) , . .= . ' '. . 193 21. Sulpho-Sinapisiue, or Sulpho-Sinapic Acid . . .194 22. Salicine . . . . - . . . 197 23. On Draconine . , . . . . .198 24. Precipitation of Morphia from Laudanum (Dr. Hare) . • ibid. 25. Colouration of Azoted Bodies by Nitrates of Mercury . .199 26. Tanning of Leather by Grape Marc . . •«,-.. . . 200 27. Analysis of a Salivary Concretion (Professor Goebel of Dorpat) . Ibid. § III.— NATURAL HISTORY. 1. Power of Carbonic Acid on the Lungs .• . . 201 2. On the Phenomenon of Blushing . . • . 202 3. General Emphysema formed by a combustible Gas . . , ibid. 4. Poisoning by Mouldy Bread » ' ... . ., . 203 5. Cure of Scrofula by Iodine . . . . ibid. 6. On the Use of the Secale Cornutum ••*••*" .... 204 7. On the Holotures, and particularly of the Holothuria physalis (Linn.) ibid. 8. Defence against Flies, used by the Butchers of Geneva . 206 9. The Palm of Chile . . . . . . ibid. 10. Destruction of Weeds in paved Paths and Courts • . ibid. \ \ . Preservation of Hay . . . . . . ibid. 12. Remarkable Propagation of Wind . '•. . . 207 13. Thoughts on North and South Winds (M. Alphonse Blanc) . ibid. 14. Nitrous Atmosphere of Tirhoot . . . 208 15. Progressive Motion of the Glaciers . . ' • • 209 16. On the Comparative Quantity of Salt contained in the Waters of the Ocean (M. E. Lenz) ... . . ibid. 17. Hourly Observations of the Barometer in the Fortress of Cavite . 211 iv CONTENTS. Page 18. Comparison of the Mean Temperature of the Air and the Water on the Surface of the Ocean within twenty-four hours . . 21 19. Professor Oltmanns on the Geography of South America . . 212 20. On Beauchamp's Geographical Positions in the East (Prof. Oltmanns) ibid. 21. Eumenian Marbles ...... 214 22. On the Illumination of Theatres— additional Remarks (Mr. Ainger) ibid. CONTENTS. Page The Mode of Preparing Human Heads among the New Zealanders, with some Observations on Cannibalism. By GEORGE BENNET, Member of the Royal College of Surgeons in London . 215 On the Transmission of Musical Sounds through Solid Linear Con- ductors, and on their subsequent Reciprocations. By CHARLES WHEATS-TONE . 223 On the Influence of the ' Sense' of Muscular Action in Connexion with Vision. By ALEXANDER SHAW, Esq. . . . 239 On the Induration of Chalk and Chalk Earth under Water, and the application of this Property in Hydraulic Architecture. By J. PENNISTON. [In a Letter to Dr. FOWLER, of Salisbury.] . 254 Further Observations upon Siliceous Deposits from the Urine. By ROBERT VENABLES, M.B., Physician to the Chelmsford Provi- dent Society, &c. . . . . 256 Notes upon Vegetable Tissue. By JOHN LINDLEY, Esq., F.R.S. 264 On Harriot's Papers. By S. P. RIGAUD, M.A. F.R.S. Savil. Prof, of Astronomy. [To the Editors of the Journal of the Royal Institution.] . . . . . 267 On the Magnetic Influence exhibited during an Aurora Borealis. By S. H. CHRISTIE, Esq., M.A. F.R.S, &c. . . 271 On the Physical Cause of Endosmosis. By M. DUTROCHET. [Read to the Academic des Sciences, 25th July, 1831] . 280 On a Double-acting Air-pump. By the Rev. WILLIAM RITCHIE, M.A. F.R.S. Prof, of Nat. and Exper. Philos. Royal Institution 288 On the Method of Observing the Fixed Lines in the Solar Spectrum. By J. T. COOPER, Esq. .... 289 On the Acoustic Figures of Plates. By Professor STREHLKE . 292 VOL. II. Nov. 1831. a U CONTENTS. Page Experimental Illustration of the Equality between the Radiating and Absorbing Powers of the same Surface. By the Rev. WIL- LIAM RITCHIE, M.A. F.R.S., Prof, of Nat. and Exper. Philos., Royal Institution .... 305 On the Penetrativeness of Fluids. By J. K. MITCHELL, M.D., Lecturer on Medical Chemistry in the Philadelphia Medical Institute ..... 307 ANALYSIS OF BOOKS. Memoir of the Life of Thomas Young, M.D. F.R.S., Foreign Asso- ciate of the Royal Institute of France, &c., &c. . 322 PROCEEDINGS OF THE ACADEMY OF SCIENCES AT PARIS. Agricultural and Rural Economy . . . 335 Botany . . . . . .337 Chemistry ..... 367 Geology ...... 371 Medical Science . . . . . 375 Natural Philosophy . . . .377 Zoology ...... 378 Miscellaneous . , . • 383 FOREIGN AND MISCELLANEOUS INTELLIGENCE. § I.— MECHANICAL SCIENCE. 1 . On the Flexure and Force of certain Woods . . • 392 2. Double Images of Objects seen through the Air . . ibid. § II.— CHEMICAL SCIENCE. 1. On the Rapid Production of Steam by heated Metals . . 393 2. Discharge of Lightning over a large Surface . . . 395 3. Becquerel on the Electric Effects produced by Heat and Pressure ; . 396 4. Crystallization of Perchloric Acid (Serullas) ... 397 5. Strength Test for Bleaching Powder . . . .398 CONTENTS. Hi Page 6. Preparation of lodic Acid • • • • . 400 7. Method of Marking Linen • • • • • ibid. 8. New Applications of Artificial Ultramarine • • . 401 9. Reduction of Titanium (Liebeg) . . , . ibid. 10. Preparation of Metallic Cromium (Liebeg) . . . 402 11. Analysis of some Mercurial Salts • • • • . ibid. 12. On the Preparation of the Iodides of Mercury • » , 403 13. On Borate of Silver (Rose) . . . . .404 14. Igniting Platina ...... 405 1 5. On organic Analysis, and on the Constituents of various organized Bodies ibid 16. Results obtained from the Seed of the Mango . . . 407 17. On Lactic Acid ....... 408 18. On Camphor and Camphoric Acid (M.J. Liebeg) . . 409 19. Action of Heat on Acetate of Lead (Matteuci) . . .411 § III.— NATURAL HISTORY. 1. Industry of Birds . . . . . . 411 2. On the Rapid Flight of Insects • . • . . , 412 3. Useful Astringent in Cases of Mercurial Salivation (M. Virey) . ibid. 4. Relief for the Tooth-ache . . . . . .413 5. Poisoning by the (Sebacic) Acid of Goose-Grease . . 414 6. Influence of atmospheric Electricity on the Eyes ... ibid. 7. Native Country of the Potatoe ..... 415 8. New Forms of Cellular Tissue . . . . .417 9. Functions of Spiral Vessels ..... ibid. 1 0. Cryptogamia in Molasses (Virey) . . . . .418 1 1 . Algerine Sirocco ...... ibid. 12. Atmospheric Electricity ...... ibid. JOURNAL OF THE ROYAL INSTITUTION 01' GREAT BRITAIN. ON THE FORMATION OF AN ARTIFICIAL COMPOUND DISPERSIVE POWER IN A COMPOUND LENS, FOR CORRECTING THE FRONT LENS OF A REFRACTING TELESCOPE. BY PETER BARLOW, F.R.S. Cor. Mem. Inst. France, &c. general principle of correcting the front lens of an object-glass for achromatism is very well understood; it consists only in making the focal lengths of the two lenses pro- portional to their dispersive powers. When this proportion obtains, and the lenses are placed in contact, the spectrum vanishes, and the object-glass is achromatic ; but when it does not, a new spectrum is formed ; and by considering the com- pound lens as a simple one, a new dispersive power is created, and this lens thus formed may be employed to correct another front lens. Also, as the artificial dispersive power thus created may be made either greater or less, in almost any proportion, than that belonging to either of the media by which the com- pound lens is formed, the correction may be made at almost any distance behind the front lens, and consequently the cor- recting compound lens may be made proportionally less than the front lens it is intended to correct. When the compound correcting lens is used in contact with the front lens, it becomes the triple object-glass of Peter VOL. II. Auo. 1831. B 2 Mr. Barlow on the Refracting Telescope. Dollond. When it is made a parallel glass for the mean rays, it agrees with the construction proposed by Mr. Rogers ; and in all its intermediate states, it is the form which I have proposed for the naturally high dispersive power of the sul- phuret of carbon. It is certainly a little remarkable that the original idea of the triple object-glass had never led to this view of the subject ; for it is obvious that if, instead of comparing the combined focus of the two crown lenses with that of the flint, we compare the combined focus of the two back lenses with that of the front, or the two front with that of the back lens, we arrive at a new artificial dispersive ratio of the kind above alluded to, but the author of this ingenious arrangement, having had in view only the reduction of the spherical aberration, seems to have lost sight of the other advantages he might have derived from the same principle. In my endeavours to supply the place of flint glass by the sulphuret of carbon, I was in some measure forced upon that step which Mr. Dollond had failed to take, by finding it neces- sary to open the lenses ; and this construction immediately re- called to Mr. Rogers an idea which he had formed some time before of that principle, which he has since published. But neither this gentleman nor myself, any more than the inventor of the triple object-glass, seems to have had any idea that we had each penetrated by different roads upon the borders only of an extensive field of uncultivated practical optics, which, if duly explored by well directed experimental researches, cannot fail of producing many valuable results. While we confine ourselves to crown and flint glass, the range is certainly rather limited: if we employ the high re- fractive glass of Mr. Faraday's manufactory, it is considerably increased ; but with the sulphuret of carbon it can be so far extended as to make the entire correction for colour, in an object-glass of any diameter, in the eye-piece of the telescope only. Mr. Coddington has, indeed, remarked, in his highly va- luable * Treatise on Optics,' that my correcting lens must be considered as a part of the eye-piece of the telescope ; but this has reference only to its theory : what I allude to above is to be understood also in a practical sense ; as it is possible to pro- Mr. Barlow on the Refracting Telescope. 3 duce the entire achromatic correction in a tube one-eighth only of the length of the telescope, and of one eighth of its aperture. In order to illustrate the above view of the subject, let / + S/= the focal length of the red ray. / = ditto mean ray. f — df = ditto violet ray. In any positive lens, let also /' + ^/', /',/'-<*'/'. represent the same quantities in another lens, having a different index and dispersive power, where S, $ denote the dispersions of the red ray in the two media, and d and d ' those of the violet ray. In most cases we consider £ = d, and ^ = d' ; it is not so, however, in all cases, and I propose therefore at pre- sent to give this generality to the notation. Confining now our investigation to one side oply of the spectrum, as for example the red, and considering the second lens as negative, we have, when the two are in contact, -- = reciprocal focus of the red ray, and i — -i, — _L = 4 - £ = reciprocal focus of / the mean ray. Consequently /a + *> -/a + *) /'-/ coloured focus ; and this therefore, being divided by the mean focus, gives (i + > + y + »y)Cr-/) _ 1 = di ion of /(I + &')-/(! + S) the compound lens, which after reduction, and denoting this dispersion by A, becomes f*(i + n -/yg + v = A (1) /d + ^O -/(I + 5) And here it is obvious, 1. if / : / :: i + U' : y + iy we get A = 0, and it becomes the common double achromatic object-glass ; in which £ ^ being very small, the proportion is generally given as B 2 4 Mr. Barlow on the Refracting Telescope. /:/':: S : y as stated in the first page of this paper. 2. If /=/' we have A = — 1, which is Mr. Rogers' correcting lens. 3. If / : /' :: 1 + S : 1 + $' the denominator vanishes, and A is infinite. And between these limits lies an immense range of disper- sive powers, almost entirely unexplored ; and out of which a well directed course of experiments could not fail of eliciting many valuable practical results. If the lenses are both positive, the expression becomes /•*(! + *') +/*'(! + *) _ A . (2) In this case A can never become zero, but it must neces- sarily fall between the two values of £ and $', and will conse- quently be less than the greater of the two. The above deductions, it will be observed, relate only to the red ray, but by everywhere changing £ into — d, and &' into — d't they apply equally to the violet ray. The expression (I) there- fore, for the violet ray, with a positive and negative lens, is and with two positive lenses it is '(l-d) _ A The former, of course, becomes zero when /:// :: d—dd' : d'-dd', which, rejecting as before dd ', as inconsiderable, gives as in the red ray f:f':d:df :: &V&V/ It follows from these formula? and equations, that although in two media we should have $' = d'y and 5= d, yet, as the combination of the red ray with the mean, would require the proportion /:/' :: (! + $')* : (! + $)*' and the combination of violet ray with the mean, the proportion /:/' :: (!-*')* : (I-*)*' we see at once, in this change of sign from + to — , the origin Mr. Barlow on the Refracting Telescope. 5 of that imperfection which is generally designated the secon- dary spectrum ; that is, the same proportion, which combines the red and mean rays, will not combine the violet and mean rays, so that there is necessarily a certain quantity of uncor- rected colour when the lenses are in contact, and the disper- sions equal on each side the mean ray, and which, with crown or plate and flint glass, is generally rendered worse by the inequality of the values of ^ and d' in the latter ; the inequality lying on that side which increases the evil : but I have shown in a paper in the ' Philosophical Transactions' for 1828, that by opening the lenses we have a certain command over the artificial dispersion which offers at a least chance of complete correction. If, in the above expression, we make/' =p/, and £' = m S, it becomes - m(l-f-S) _ p (1+niJ) - In which A denotes, as before, the dispersion of the red ray in the compound lens, £ that of the red ray in the plate or crown lens, and m $ that of the other medium, whether it be flint glass, Faraday's glass, or sulphuret of carbon : m and £ are therefore given quantities, while p is assumable at pleasure within all practicable limits. At present we have considered the lenses, whose compound dispersion has been ascertained as being in contact ; let us now inquire into the circumstances of the compound disper- sion due to two lenses placed at a distance from each other. Let the focus of the first lens be nf, and let the cone of rays from this lens be intercepted by a second lens at the distance / from the focus of the first ; then n S/will be the coloured focus of this first lens, that is to say, there will be all the colour due to the focus nf, but reckoning only from the place of interception the focus being/, we shall have - — i=- n $ the dispersion of this ray, estimated from the second lens : we have, therefore, only to substitute n £ instead of S in our former expression, and we shall thus obtain the value of the disper- sion of the compound open lens, viz., in this case we shall have 6 Mr. Barlow on the Refracting Telescope. for the red ray with a positive and negative lens, /'(I for the violet ray, for the red ray, both lenses being positive, we shall have f'n $(1+80 + /S'(l-f-rcS) - A . ~7r(l + ^)+/(l+7i^) for the violet ray where it is assumed that the dispersion is equal on each side the mean ray, as is the case in crown or plate glass, which is the medium to which this principle is more particularly appli- cable ; and here again, as we cannot completely answer both conditions, so as to combine the red and violet with the mean ray, we must, as in the case of the common double or triple object-glass, take a mean value of A by rejecting n 3 and $ as inconsiderably ; this reduces the expressions to /»nS±/y _ A f'±f the upper signs applying to the case of two positive lenses, and the lower to a positive and negative lens. Taking this view of the subject, we must, in the combination of two lenses to correct the front lens of an object-glass, con- sider it rather as a combination of the two distant crown lenses, to be corrected by the simple flint lens, at least this will be the most convenient form for computation. For example, the focus of the compound lens will be its dispersion = A ; and calling the dispersion of the flint I", we have only to compute its focus ff" by the common analogy adopted in the usual form of telescope, viz. A : J" :: /" :/'" that is w = ^' *" Mr. Barlow on the Refracting Telescope. 7 It would extend this article to too great a length to enter into the various cases that arise by giving different values to n and/' in this expression. I shall therefore, simply for illus- tration, take the particular case proposed by Mr. Rogers, in which it is assumed that £ = £', the first and second lens being both crown, and /=/'", the foci of the second and third lens being equal : this gives / ff'V . As an example, suppose the correcting lens to be placed at half the focal length of the front lens ; and the focus of the front lens n/= 84 inches, and that the correcting lens is com- posed of crown and English flint glass, of which the relative dispersions are as 2 to 3, that is § = 2, S" = 3 and n = 2, con- sequently, /= 42, we should have /' = 3""2 x 42=10-25 inches, 4 that is, the focus of each of the lenses forming the compound correcting lens must be 10£ inches, the whole length of the telescope being 84 inches. As another example, let the correcting lens be composed of crown and Faraday's glass, of which the relative dispersions are as 10 to 19. Then we should have />= 19-10 /- 18.9 inches, 2x10 that is, the focus of each of the correcting lenses must be 18.9 inches. Lastly, let the correcting lens be crown glass and sulphuret of carbon, the relative dispersions being as 3 to 10. Here we should have /'=10~3/=: 49 inches. 2X3*7 We see thus the great advantage of a high dispersive power in this form of construction : for, in consequence of the depths of the curves required in the first example, it would be prac- cally impossible to take n greater, or at least very little greater, 8 Mr. Barlow on the Refracting Telescope. than 2; with Faraday's glass, the focus being nearly double and the refractive power very great, the curves will be of much greater radii, and the principle would admit of some consider- able extension ; but with sulphuret of carbon it may, as has been stated in a former part of this article, be pushed so far as to enable us to make the whole correction for colour in the eye-tube only, that is, in a tube of Jth orith the focal length of the telescope. We have seen, for example, — still taking the whole focus, 7 feet or 84 inches, — that when n - 2, / = 42 and /' = £ / s= 49 inches. If n = 3, / = 28 and /' = \f = 21TV inches. If n = 4, /= 21 and /' = •&/= llf inches. If n - 5, /= 16.8 and/' = •&/= 7li inches- If n = 6, /= 14 and /' = T78 /= 4f inches. If n = 7, /= 12 arid f rr /T/= 4 inches. If n == 8, /= 10£ and /' = & f = 3-fo inches, which latter case even (having regard to the reduced aper- ture) is still as practicable as the flint and crown corrector at half the focal distance. With Faraday's glass it has been shown, that with a focus of 84, and with n = 2, we have — n = 2, /= 42 and /' = ^/= 18.9 inches. If n = 3, / = 28 and /' = -£, f = 8.4 inches. If 7i = 4, /:= 21 and /' = -^ / == 4.7 inches. If n =: 5, /== 16.8 and f = ^9 /= 3.02 inches, the case n = 4 being perfectly practicable. Thus it appears the greatest extension that can be given to this principle with flint glass is n = 2 ; with Faraday's glass, n = 4, and with sulphuret of carbon, n = 8 : that is, in the first case, a plate lens of any aperture can be corrected with a flint lens of half that aperture ; with Faraday's glass, by a lens of one-fourth the aperture ; and with sulphuret of carbon, with a lens of one- eighth the aperture : and it will be observed that, between the values of n = 1 and n = 2, each of these mediums admit of unrestricted application — the case n = 1 in each being the triple object-glass, under that particular arrangement in which the focus of the first lens is equal to the focal length of the telescope. Mr. Barlow on the Refracting Telescope. 9 All the above variations may be considered as belonging to one class, distinguished by the condition of /' being equal to /"'. Another class belongs to the case of /"' = 0, which is the form I have adopted in my fluid telescope. In this the range is more limited : we cannot here with any advantage make n greater than unity, while we employ flint-glass. With Faraday's glass, we can make n any number between 1 and 4f ; and with sulphuret of carbon, any number between 1 and ^. In the former class the focal power remains throughout the same as the length of the telescope ; but in the latter it may be increased with the sulphuret of carbon to nearly double the length, and with Faraday's glass to l£ times the length. It is not, however, necessary to confine ourselves to either of these classes: we may make f" = qf'9 and take (/, any number within practicable limits, greater or less than unity ; and while q is less than unity, the focal power of the telescope will be increased, and with q greater than unity, it will be diminished. Hence it appears that the refracting telescope, which has for about eighty years been limited to one particular form, will admit of an immense variety of untried forms, some of which seem to offer important advantages. In all these cases, for example, the size of the concave cor- recting lens, which has hitherto set a limit to the dimensions of refracting telescopes, may be considerably diminished, leav- ing the aperture and light the same ; or, which is equivalent with any given correcting lens, we may employ a much greater front lens. In one class, also, we can, by increasing the focal power, diminish the length of the telescope ; and in another, by dimi- nishing the focal power, increase the light. We have, also, — as I have shown in the ( Philosophical Transactions' for 1828, — at all events a control over the amount of the secondary spectrum, if not the power of destroying it altogether; and, lastly, the error arising from spherical aber- ration may be diminished almost without limit. On the latter subject it may be asked, how (as we destroy or counteract the spherical aberration entirely in the common telescope) can it be farther diminished? To this I can only reply, that however completely we destroy it in our formulae, 10 Mr. Barlow on the Refracting Telescope. it is still practically existing in the telescope ; that is, we can only destroy the aberration for one index, whereas the perfec- tion of the instrument requires it to be destroyed for three ; an error, therefore, must remain, and it is for this reason that, with a given aperture, opticians are compelled to employ a certain length of tube, or rather, not less than a certain length ; and, unfortunately, that length increases in a higher ratio than the aperture. The only remedy, therefore, is a reduction of the curvatures; and in some cases included in the above classes, these curvatures may be reduced to one-eighth of those of the common telescope of the same focal power ; but to what extent we may in consequence reduce the length of the telescope, can only be satisfactorily determined by experiment. Unfortunately, such experiments are attended with great expense ; and that expense is rendered greater than is neces- sary, because many of our observers, however competent they may be to judge of the performance of a telescope, have too little inclination to examine theoretically and judge of prin- ciples ; and therefore to gain their assent to any new form of construction, the instrument must be perfect, which of course requires the most perfect glass and the best workmanship, and necessarily creates great expense : whereas, if they were able or content first to examine principles only, the charge of such experiments would be much diminished ; and when the best principle had been selected, then, and not till then, I would incur the expense of perfection. It is exceedingly difficult, with such a field of inquiry before one, to say which of all the different cases should be selected as an individual test. I have, however, suggested a form, and the Royal Society have ordered the instrument to be con- structed, which I have every reason to hope will be found highly advantageous. In this, the amount of spherical error, — or, which I consider equivalent, the amount of curvature, — will be less than one-eighth of what would belong to the com- mon telescope of the same focus. The focal power will exceed the focal length, and the sum of all the refractions in the passage of the rays through the lenses, as well as at each in- dividually, will be reduced to a minimum.. These appear to Mr. Barlow on the Refracting Telescope. 11 me to be important advantages ; but there may be others equally important which have escaped me, and over which, had they occurred to my mind, I might probably have been able to exercise some control. This impossibility of foreseeing all the bearings of an in- quiry so completely untried as that which forms the subject of this paper, proves the necessity of an extensive series of expe- riments to elicit the most useful results ; but such a series of experiments, particularly under the disadvantage to which I have alluded above, involves too great an expense to be under- taken at the charge of a private individual. At the same time, I must think that an extensive field of practical optics is here opened, which is highly deserving of cultivation. ON THOSE BIRDS WHICH EXHIBIT THE TYPICAL PER- FECTION OF THE FAMILY OF ANATID^S. By WILLIAM SWAINSON, Esq., F.R.S., L.S., &c., &c. A LTHOUGH natural history, from having been formerly •^^pursued with an exclusive reference to specific differences, long merited its popular definition of being a science of ob- servation, the attention now bestowed upon the generalization of facts, gives the hope that this science will soon become one of demonstration. It is to be feared, however, that in this eager desire to develope general laws, we sometimes overlook those means by which such results are to be obtained, — that we theorize, as it has been well observed, where we should ana- lyze*, and decide upon the properties of a group, thought to be natural, before we have thoroughly investigated the group itself. The present generation of naturalists, in fact, are as much prone to fall into error from their over-anxiety to gene- ralize, as were those of the Linnsean school, from an exclusive devotion to specific differences, and a total neglect of all the higher objects of the science. This passion for theory, among our own countrymen, dates its origin from the period when naturalists began to study the celebrated • Horse Entomolo- * ' It is the prevalent error of the day, among the naturalists, to attempt to generalize where they gught to analyze.'— Bicbeno, Linn. Tr. xv. p. 489. 12 Mr. Swainson on the Typical Perfection gicae ;' and when they perceived that the variation of animal structure could only be explained upon the principles there promulgated. But regardless of the warning which the talented author of that work has so often given to his disciples, that nothing is more easy than to form circles upon paper, ' provided we do not consider it necessary to prove them,' the fascination of his theory has been such, that some of his fol- lowers— forgetful of the discriminating caution of their master, and overlooking those tests which he has himself applied to the only genera he has perfectly analyzed — have ventured to pronounce certain groups to be natural and circular, which, upon closer investigation, prove eminently artificial. Certain forms are fixed upon as types of structure, before the prin- ciples which regulate such types have been either explained or discovered. An arbitrary standard of perfection is thus planted, around which are assembled such other species as more or less approximate to this fancied point of excellence ; as this, however, is founded upon no one fixed principle of natural arrangement, every systematist thinks his own type better than that of his predecessor. It appears to me, therefore, essentially necessary to the stability of any system of zoology professing to be natural, that the doctrine of types should be more deeply investigated : since, if such forms do actually exist in nature, we are justified in believing they must be regulated by certain general laws, which, when developed, will be conspicuous in all natural groups of animals. At all events, no arrangement can be demonstrative which is in any degree founded upon an assump- tion, like that of types, as they at present stand. It cannot be too often repeated, that all true knowledge of zoology rests exclusively upon analysis — upon a perfect acquaintance not only with the organization of a species, but with its habits, instincts, and natural history, properly so called : to fix, a priori, upon the type of a genus, or upon the divisions of a family, before the first has been demonstrated, or the latter analyzed, is manifestly erroneous : it is clearly beginning at the wrong end ; and we do no more than tread in the foot- steps of our predecessors, who first established certain rules of their own for making genera, and then referred every new of the Family of Anatida. 13 object to these arbitrary divisions. If this error led to so much confusion'and to such forced combinations before any pretence was made to discover the natural system, it is fraught with peculiar evil in these days, when a glimpse of the harmonious plan of the GREAT CREATOR is the ultimate object of every zoologist. By fixing a priori upon a type, and arranging all the subordinate groups in their several supposed relations to that type, we not only incur the risk of commencing in error, but of continuing it through the whole contents of a very large division, and an entire order of animals will thus be inevi- tably thrown into confusion. It must indeed be admitted that, with our present imperfect knowledge of the laws of nature, we must, in many instances, be content with theoretical deductions: but we should ever bear in mind, that these theories must be relinquished when opposed to a better knowledge of facts, and the right interpre- tation of such facts. It has been well observed, that every great discovery has originated from some preconceived theory which has struck open a new path of inquiry, enlarging and expand- ing the mind at every step. No one will, therefore, deny the importance, much less the legitimate use of theory, as an instru- ment necessary to develope the greatest truths : the objections are not to its use, but to its abuse. Every naturalist, in fact, who does not confine his attention to the sole study of species must have a theory or a system : it may be borrowed, or it may be new, true or false ; still, so soon as he attempts combina- tions, he becomes essentially a theorist. He sorts and sepa- rates his species into parcels or groups, under some definite notions as to the characters they possess. If, after having done this, he proceeds to verify his first impressions by criti- cally examining their correctness, or, in other words, by ana- lyzing his groups, he makes that just and legitimate use of theory which is allowable : but, on the other hand, if he con- tents himself with investigating the details of one of his groups, and, having discovered certain properties belonging to it, pro- ceeds to apply these results to the remainder, taking it for granted that further analysis is unnecessary, he (hen invests theory with an importance to which it is not entitled. So 14 Mr. Swain son on the Typical Perfection long, indeed, as the world of science is distinctly informed that the arrangement of the one is the result of analysis, and that of the others is theoretical, no mischief is done : on the con- trary, the doubts which would be expressed upon the latter, particularly by an able and candid writer, will frequently lead to important discoveries. At all events, we should know how to apportion our confidence ; which would certainly be greater upon that group which had been analyzed, than upon those which rested upon mere theory. The inventor of an artificial system has no occasion to lay his reasons before the public ; but those who propose natural arrangements are imperatively bound to candour upon these points. Since no name, how- ever great, no style, however persuasive, or no theory, how- ever captivating, can be of the least weight when unsupported by analysis. The consequences which have resulted from this anxious desire to generalize, are no where more conspicuous than in the existing arrangements of the Anatidse ; a family of birds to which our attention has been recently directed, as form- ing a considerable portion of the ornithological collections made by Dr. Richardson, and described in the second volume of the ' Northern Zoology,' now almost ready for publication. This family, whose geographic range is chiefly in the temperate and arctic latitudes, has long excited the attention of European ornithologists. The species are numerous, and the modifica- tions of form so many, that no one group of ornithology of equal extent, except, perhaps, the Falconidffi, has been so much divided into genera and sub-genera. Upon the value of these minor divisions, there is, of course, much diversity of sentiment, the inevitable consequence of an opinion almost universal among naturalists, that nature knows no other defi- nite distinctions than those which separate species. The truth of this, however, has already been questioned * ; and it will be my object, upon this occasion, to prove that the views of Mr. Macleay, in regard to his definition of the term genus, (as exemplified by him in those of ScarabcEus and Phanceus,) are * Mr. Macleay's Examination, &c. Zoological Journal, vol. iv. p. 406. of the Family of Anatidce. 1 5 substantially correct, and, that a genus, so interpreted, is a definite group *. The most superficial observer, on looking to the family of the ANATID^E, or Ducks, under which he will include the geese and swans, must be struck by the remarkable shape and structure of the bill, to- tally different from that of all other birds. This, in fact, is the only group in the aquatic order wherein the bill is very considerably dilated in its breadth, and of a texture unusually soft. In addition to these, a third, and a very important cha- racter is discerned : the cutting margins of the bill are provided with numerous transverse lamellar plaits, so much developed in some species, as to project beyond the bill ; thus assuming an analogy to the teeth of quadrupeds. This analogy, however, is more imaginary than real, since these appendages are des- tined for a very different purpose. The feet, although in general short, are adapted to more than one purpose, since they are not only used for swimming and diving, but for walking. The adoption of this structure is in admirable unison with their natural habits, and with the station that ALMIGHTY WISDOM has ordained them to fill in the great empire of Nature. The Gulls feed indiscriminately upon marine ani- mals, whether living or dead : they are the purifiers of the waters, as the Vultures are of the land. The Pelicans and the Penguins derive their support from those large fish which the more feeble Gulls can neither capture nor swallow, while the Terns skim the ocean in search of small fish which rise to the surface. But the inconceivable multitudes of minute animals which swarm, as voyagers assert, in the northern seas, and the equally numerous profusion inhabiting the sides of rivers and fresh waters, would be without any effectual check upon their increase, but for a family of birds destined more particularly for that purpose. In the structure, accordingly, * Strange as it may appear, not one of Mr. Macleay's disciples have adopted the views of their master on this highly important question. The definition of a genus, given in the Zoological Journal, vol. iii. p. 97, &c., is diametrically opposed to that of the Hor* Entomologies. The one is founded upon abstract reasoning, the other upon demonstration. 16 Mr. Swainson on the Typical Perfection of the Ducks, we see all these qualifications in the utmost perfection. By means of their broad bill, as they feed upon very small and soft substances, they capture at one effort considerable numbers. Strength of substance in this member is unnecessary : the bill is therefore comparatively weak, but great breadth is obviously essential to the nature of their food. As these small insects, also, which constitute the chief food of the Anatidae, live principally beneath the surface of the mud, it is clear that the bill should be so formed that the bird should have the power of separating its nourishment from that which would be detrimental to the stomach. The use of the laminae thus becomes apparent : the offensive matter is ejected be- tween their interstices, which, however, are not sufficiently wide to admit the passage of the insect food at the same time. The mouthful of stuff brought from the bottom is, as it were, sifted most effectually by this curiously-shaped bill ; the refuse is expelled, but the food is retained. It is probable, also, that the tongue is materially employed in this process ; for, unlike that of all other birds, it is remarkably large, thick, and fleshy. From being so highly developed it must be endowed with an unusual degree of sensation ; and, indeed, a very exquisite sense of taste must belong to any animal which has to sepa- rate its food from extraneous substances, without deriving any assistance in the process from its powers of sight : against this deficiency Nature has wisely provided, by heightening and in- creasing the senses of taste and touch. I am acquainted with no family of birds where this organ is similarly formed, excepting that of the Psittacida. The tongue of the Parrot, as every body knows, is so thick and fleshy as to resemble that of man. It is, however, much shorter and less delicate than that of the Duck ; and, although endowed, in all probability, with sensations somewhat similar, the more immediate purpose of its struc- ture is very different. Those who are familiar with the man- ners of Parrots, in their native regions, well know that they feed not only upon soft fruits, but upon others of the hardest texture. The seeds, for instance, of the numerous palms of Brazil are the most favourite food of the Macaws ; and the thousands of Parraqueets swarming in tropical America always prefer nuts to fruits. This, in fact, is clearly evinced by the of the Family of Anatida. 17 great power of the bill. A thick and strong tongue thus becomes necessary, not so much for taste as to assist the parrot in turning round the nut that is to be cracked ; it aids the efforts of the bill, supports the fruit in a steady position, nnd assists in turning it to a more vulnerable part. It is, therefore, to the formation of the bill, as more parti- cularly connected with the peculiar habits assigned by Provi- dence to this family, that we must look for its typical dis- tinctions ; no other of its characters, I apprehend, can be selected, since the rest are common with several other aquatic families. There is nothing peculiar in the diving of Ducks, since the dab-chicks do the same ; or in their frequenting both land and water, for so do the Gull family. If, there- fore, this line of reasoning be just, it follows that we must esteem that form to be pre-eminently typical of the whole family, which exhibits these peculiarities of the bill in the highest state of development. Every ornithologist will conse- quently point to the Shoveller Duck as a fit representative of the GENUS ANAS ; and as a form which differs from all others found in Europe by the uncommon breadth of its bill, and by the delicacy and great development of the projecting laminae. We have had frequent occasion to remark*, and to demonstrate the truth of the observation f , that such birds as are typical of a very compre- VOL. U. * Encyclopaedia of Geography, now in the press. I See ' Northern Zoology,' vol. ii. AUG. 1831. 18 Mr. Swainson on the Typical Perfection hensive division, enjoy an extent of geographic range far above all others. The Shoveller Duck of Europe is not only found from the northern regions to the table-land of Mexico *, but is stated to inhabit the Coromandel coast, and other parts of India j ; while another species, precisely of the same form, is recorded as a native of Australia J. The geographic distribution, then, of the true Shovellers may be termed universal. But among these broad-billed Ducks of the southern hemisphere, we find a very remarkable modi- fication of form ; the breadth of the bill and the length of the laminae are nearly the same, but the edge of the upper man- dible, instead of being smooth, as in the European species, is furnished with a thin membranaceous skin, which conside- rably projects, and hangs down somewhat like a wattle on each side. For this form, hitherto uncharacterised, I now propose the name of MALACORHYNCHUS, and I shall view it, for reasons hereafter stated, as a sub- genus. The bill of the European Shoveller is flexible ; but in this group it is much more so. One species, described by authors under the name of the soft-billed Shoveller, can scarcely exhibit this debility more remarkably than another which is now before me : it came from the same country, * Specimens communicated to me by John Taylor, Esq., F.R. S., &c., from this locality, differed not from those brought home by Dr. Richardson. f Lath. Gen. Hist., x. 312. J New Holland ShoTeller, 1. x. p, 313. of the Family of Anaiidce. 19 and seems to be undescribed. Guided by the same views, we next inquire what other ducks present us with the pro- jecting laminae of the Shovellers ; or where we shall look for the gradual diminution of a structure so important to these birds. This diminution we find in the sub-genus, CHAULIODUS, of the ' Northern Zoology,' founded upon the well-known Gadwall duck, a bird so repeatedly described, that it is sur- prising how any part of its structure should have escaped observation. It is, however, certain that this bird makes as near an approach to the Shovellers as any other yet known. The form of the bill, indeed, is no longer spatulate, or percep- tibly broader towards the end ; but the laminae of the upper mandible are still very fine, distinct, and more numerous than those of any other form subsequently mentioned, for they project a full tenth of an inch beyond the margin. The tail now begins to be lengthened, and, in a new species from Africa (C. Capensis), which I have recently received, is so much attenuated, as to evince an evident affinity to the pin-tail duck, forming the sub-genus DAFILA, of Dr. Leach. Nature has now so far receded from the typical form, that one of the chief peculiarities of that structure is nearly lost, and another considerably modified. The laminee of the upper mandible, which, in the Chauliodus strepera (Sw.), are so much shorter than those of the true shovellers, and are still more abbreviated in C. Capensis, become almost concealed by the margin of the bill in the bird now before us. The most C 2 20 Mr. Swainson on the Typical Perfection striking characteristic, therefore, of the genus we are now considering has nearly disappeared, precisely in that form which is furthest removed from the type. But the shape of the bill, although essentially modified, has not undergone a total alteration : its breadth towards the tip is not only as great as at the base, but is even more dilated ; so that, in this respect, it resembles the Shovellers more than the Gadwalls, while it differs from both in being higher at its base, considerably more lengthened in proportion, and much more convex throughout. It assumes, in short, a semi-cylindrical form, the end being particularly obtuse and slightly dilated. The precise point of junction between the Pin-tails and that group which was known to the ancients by the name of BOSCHAS, has not yet been explained. Under this subgenus we compre- hend all those ducks usually denominated Teals, together with the Mallard, long domesticated in our poultry yards. As this is by far the most numerous group, so it exhibits a greater diversity of form among the species. They are all, however, characterised by a bill longer than the head, whose breadth is equal throughout ; it is sometimes, indeed, a little dilated, but never contracted at its tip, while the laminaB of the upper man- dible are entirely concealed by the margin of the bill. The neck and the tail, which in Dafila are both considerably length- ened, are much shorter in this group, which is further distin- of the Family of Anatidce. 21 guished by the brightness and beauty of plumage observed in nearly all the species. On comparing the bill of the common Teal with that of the Pintail, we see a close affinity between the two forms. But as the tail of the first is so much developed, in comparison to that of the Teal, it becomes essential to discover, if these sub- genera actually followed each other in nature, what species united them more closely. By the uniform liberality of the zoologists attached to the British Museum, and more par- ticularly J. E. Gray, Esq., 1 am now enabled to do this. The beautiful Anas (Soschas) formosa, Sw., or Baikal Teal of methodists, is precisely a bird which intervenes between these two sub-genera. Essentially a Teal, it differs from all others I have yet seen in the superior length of its tail, the feathers of which are a full inch longer than the under covers*; while the convexity of the bill, from being greater than in the common Teal, establishes its close approximation to Dafila. Proceeding thus by analysis, we find several foreign species which may be either called Teal or Ducks. The Boschas Javensis, Sw., is more especially a bird of this description. It is closer allied to the mallard than to any other of the group : this is indicated by the more depressed form of the bill, and the white collar round the neck ; the nape also is very conspicu- ously crested, a peculiarity found in no other group of the * In Amis (Boschas} crecca, the tail is so short, that the under covers reach almost to the tip of the middle tail feathers, 22 Mr. Swainson on the Typical Perfection genus. To this and to the curled tail of the tame duck, we shall presently advert. Having now reached what appears to be the typical form of Boschas, we see that nature, as usual, again departs from it. The bill of the Mallard is throughout more depressed than that of the common Teal. This depression, in fact, from being greater than that of the Gad wall, or of the Pintail, obviously assimilates more to the Shoveller. The affinity, however, ap- pears remote, since the laminae of the Mallard are concealed, while those of the Shovellers are conspicuously projecting. If, therefore, the affinity was immediate, it could only be demon- strated by a species having the bill of the common Duck but with the laminae projecting. Now such a species is actually the blue winged Teal of North America, in which these laminae project nearly as much as in the Gadwall, while the upper mandible exhibits that peculiar sinuosity towards the base which is seen in no other ducks besides the Shovellers. If this affinity required any further support, it is placed beyond doubt by the fact mentioned in the ' General History of Birds,' that the plumage of the New Holland Shoveller, excepting the white facial crescent, is precisely the same as that of the blue winged Teal, — the very bird which thus unites the subgenus Boschas to that of Anas, and completes the circle of the whole group. Zoological circles, however, if founded in nature, rest upon much better testimony than mere opinion. I have attempted to prove, in the forthcoming volume of * Northern Zoology,' that the variation in animal structure is regulated by certain of the Family ofAnatidce. 23 fixed laws, to the test of which every group thought to be natural must be brought. I shall therefore now proceed to demonstrate the accuracy of the foregoing observations, con- densing them into the following tabular form. GENUS ANAS. Bill longer than the head, depressed nearly its whole length. The base not enlarged, the tip very obtuse ; the laminae of the upper mandible generally projecting. Hinder toe not dilated, short : claws short, thick. Fig. 2, a. 1. Typical Group, Sutyenera. Bill spatulate, simple ; laminae considerably projecting. ANAS. Lin. 2. Sub Typical Group. Bill spatulate, furnished with a lobed membrane ; laminae IMALACORHYNCHUS Sw considerably projecting. J 3. Aberrant Group. Bill of equal breadth, projecting laminae short, slender, IQ o acute, crowded. J Bill more cylindrical, lengthened ; tail long. DAFILA, Leach. Bill depressed, of equal breadth ; laminae distant, obtuse, \-Rnaf _ *„« and generally concealed ; tail short. jtf OSCUAS, Anfcq. On proceeding to trace the ANALOGIES of this genus, I am aware that it would be more satisfactory to compare it with the other groups of the same order and family. But this could not be done without assuming the correctness of the groups themselves, since the natural divi- sions of the Natatores, and the sub-families of the Anatida, rest, at present, upon mere opinion ; — they have been predi- cated, but not proved. I must, therefore, content myself with tracing how far the foregoing series partakes of those analogies which belong to the different groups of perching birds ; whose circular affinities I have elsewhere attempted to demonstrate. This comparison, indeed, will be much more difficult than the former, since the strength of the analogies between two given groups is always in proportion to the proximity of these groups in the great scheme of nature. It would scarcely be necessary to advert to this obvious truth, did I not apprehend that some writers, who have as yet given but a superficial consideration to the subject, will pronounce these comparisons altogether fan- ciful. This, however, is not precisely the question. No one 24 Mr. Swainson on the Typical Perfection •who lays claim to the title of naturalist, practical or scientific, in these days, can deny the difference between analogy and affinity ; still less would he be bold enough to argue, that the whole of creation is not a book of emblems, in the construction of which there must be a plan, a harmony, and a design, per- fect and consistent in all its parts. If, then, analogies exist, as distinct from affinities, they must be universal. They may, indeed, be so clear and immediate, as to strike every one with a conviction of their truth : or they may be so disguised or remote, as to lead shallow reasoners to pronounce them fan- ciful; more particularly as of late much reason has been given, by the speculations of certain continental writers, for such imputations. That, however, which is fanciful, can never be twisted into regularity ; for the moment a theory is found to explain facts which have never been explained by any other, it ceases to be fanciful. Having stated thus much, I shall proceed at once to com- pare the Shovellers, the pre-eminent type of the genus, and of the whole family of Anatidse, with the Conirostres, that being the typical division of the order Insessores, or perching birds. Both agree in being the types of their respective circles, and in their wide, if not universal, geographic distribution. For what particular office the singular lobed membrane of Malaco- rhynchus is intended, must remain at present unexplained ; but every principle of just reasoning authorises us to con- clude, from analogy, that it is intimately connected either with the nature of the food or the manner of capturing it, peculiar to these birds ; it is remarkable also, that this mem- brane is situated precisely at that part of the bill which in dentirostral birds is occupied by the tooth ; both, in fact, are appendages ; and the triangular membrane of these ducks is shaped much in the same way as the tooth of the Shrike. The colour of a species now before me strengthens this analogy, since it is banded all over with those black stripes which so particularly distinguish the American Thamnophilince, or bush- shrikes. We may then fairly liken the sub-genus Malacorhyn- chus to the Dentirostres. In the Gad walls we have a very peculiar plumage: it is generally grey, and always dull. The British species is dis- of the Family of Anaiidce. 25 tinguished from all other ducks of this division by its flying with great rapidity. This has been observed by Wilson (Am. Orn., viii. p. 121), who adds the important fact, that * it is a very quick diver.' Bewick also remarks, that ' these birds shew themselves expert in diving as well as in swimming, for the instant they see the flash of the pan, they disappear, and dive to a distant secure retreat.' Now as this power of diving is not one of the characteristics of the typical Ducks, and is much more conspicuous in the Gadwall than in any other, the fact can receive no other explanation than by supposing this sub- genus to represent the order Natatores, and consequently the Fissirostres. The former are the dullest in their plumage, and the most aquatic in their habits ; while the latter, which includes the Swallows, are the swiftest fliers in the whole circle of ornithology. Precisely as is the Gadwall in its own group. The pintail Duck, independent of its pointed tail (a charac- ter which it shares Avith the Widgeons, and the sub-genus Harelda, Leach) is remarkable for its long neck, and for its narrow lengthened bill. Now every ornithologist is aware that all such birds as have these parts greatly developed, belong either to the order of Waders or to the tribe of Tenuirostres. The long necks of the herons, the curlews, the cranes, in short of nearly all the Grallatores, incontestably prove this ; and if we look to the Humming and other suctorial birds of the tenuirostral type, we see that both groups are more especially characterised by these marks*. There now remains but one division of the genus to be tested, and this must be compared both with the Scansores and the Rasores. Let us look then, to those peculiarities which especially distinguish the common duck, the Anas (Bos- chas) domestica of Linnaeus. First, its bill, from having the laminae so short as not to project beyond the margin, is more entire than any other. Secondly, it appears to be that pecu- liar species which has been endowed by ALMIGHTY WISDOM with a disposition favourable to domestication. In every cli- * Montague, whose writings are replete with original and important facts, was the first to record that the male Pintail undergoes an annual change of plumage. Now this is one of the strongest peculiarities of the order Grallatores and of the Tenuirostres. In these groups, and these only, is this annual change almost universal* 26 Mr. Swainson on the Typical Perfection mate and in every country, where man assembles around him the mute companions which live and propagate under his care, the Mallard, almost exclusively, is the only Duck which is seen in this state. How many attempts have been made to domes- ticate others, and how completely, for all practical purposes, have they failed ? Thirdly, there is a very elegant and peculiar developement of tail in this species, and several others of the same group have lengthened crests, at the hinder part of the head. Further, this bird is not only more terrestrial in its habits than any we have here noticed, but differs from all these in frequently constructing its nest at ' some distance from the water/ and even in high trees and towers *. In several spe- cies the under plumage is regularly and beautifully spotted ; and in others the tertial feathers are richly ornamented and curved in an unusual manner. Although the Teals are generally considered the smallest race of ducks, yet they are not the typical examples of this particular group ; while the Mallard and the other flatter-billed species are, unquestionably, the largest in the whole circle. I have thus brought together, under one view, every peculiarity, whether of external form or of habit, that can possibly be selected as in any way pecu- liar to the Mallard, when viewed in reference to that parti- cular group with which it is here associated ; we shall now see that every one of these facts illustrates, in the most complete manner, the analogy of this sub-genus to the rasorial and the scansorial groups. The order Rasores is remarkable for birds having an entire bill : it comprehends the peacock, the turkey, the pheasant^ and the fowl: all those land birds, in short, which seem set apart for domestication by man. In this assemblage, also, we find the most beautiful and singular development of the tail, the most elegant crests, and the most decided partiality for living on the ground. In this order, likewise, we have the most striking examples of a spotted plumage, witness the pea- ' ' Many instances are recorded of the common duck depositing her eggs at a considerable height from the ground : one, mentioned by Mr. Tunstall, was found sitting upon nine eggs on an oak, twenty-five feet from the ground. — The author of the " Rural Sports" also records an instance of a duck taking possession of the deserted nest of a hawk, in a large oak.' — Montague, Orni. Diet. Suppl. Many other instances are mentioned in the popular compilations. of the Family of Anatidce. 27 cocks, the guinea-fowl, and the whole family of pheasants ; while the plumage of many are lineated in a manner precisely similar to that of the different species of Teal. It is among rasorial birds, that we perceive that extraordinary beauty and elongation of the tertial feathers, which is so conspicuous in this particular group of ducks, and both comprise the largest birds yet discovered in their respective circles. This analogy, in short, which can hardly be rendered more complete, ex- plains, also, the striking and apparently anomalous habit of the wild duck building so often in the hollows of trees, and in similar situations, since this habit more particularly belongs to the whole tribe of Scansores, which corresponds to, and repre- sents the order of Rasores. Having now illustrated the whole of these inferior divisions, I proceed to offer the following table as the result. GENUS ANAS. ANALOGIES. Orders of Birds. Tribes ofPerchers. Typical characters. Subgenera. fTvDical in their respective 1 INSESSORES . CONIROSTRES -j ^r^es [ANAS T» (Bill dilated into a lobe or],r RAPTORBS . DENTIROSTRES^ tootk J>MALACORHYNCHUS Each of these three columns, it will be observed, forms a circular group, of which the two first have long been before the public ; and although their analogy with the types of form in the genus Anas, are of necessity remote, they are nevertheless unques- tionable. When we consider, in fact, the great dissimilarity between the groups here compared, we can only feel astonish- ment that they possessed any one character in common. It would, indeed, as I before stated, have been better had the sub- genera of Anas been compared with the groups belonging to its own family, but this would have far exceeded the proper limits of my paper. On a future occasion I may possibly take up another portion of the subject. External structure and na- tural habits are thus proved to be in perfect unison with each other, and both combine to furnish another proof that the system 28 Mr. Swainson on the Typical Perfection of Nature is essentially a system of types and symbols. Seeing then that this system can never be developed without the aid of those matter-of-fact naturalists, — those true students of nature, who throw aside ponderous systems and observe facts, how much it is to be regretted that the natural history of birds has been so greatly neglected ! But for the writings of Le Vaillant and D'Azara, among foreigners, and those of White, Wilson, Montague, and Selby, in our own country, the true naturalist who sought to apply isolated facts to general truths, would receive but little help from all that has been Written on the sub- ject *. The most trivial circumstance in the habits and eco- nomy of an animal, may ultimately prove to be just as im- portant in deciding its place in nature, as any other belonging to structure : both are equally essential, both must harmonize, both confirm, and strengthen each other, and both illustrate general laws. This has been exemplified in the preceding pages, and we can only regret that the natural history of these birds (otherwise so well known as species) has not enabled us to do this more effectually. Yet while we 'give just and due "praise to such writers, we cannot join in the attempt of their admirers, to place them upon the highest pinnacle of fame. The study of nature is as diversified as it is vast, and requires to be pursued by different modes, and by different capacities. Without the aid of the systematist, or of the ' closet' naturalist, the whole book of the creation would exhibit but a ponderous collection of isolated facts, interesting indeed in themselves, but crude, uninviting, and trivial to the philosophic inquirer. If natural history can teach nothing more than that one bird built on the ground, and that another constructed its nest upon a tree, it may be a rational recreation, but it can never become a science. In regard to the tabular disposition of the five sub-genera, or types of form, given in the preceding pages, it will be expected that I should say a few words, since it is at variance with the mode of exhibiting circular affinities, adopted by that distin- guished writer who first detected this arrangement. On this * Anatomical facts, of course, are equally important with those of habit, and in Mr. Yarrell we can now boast of an ornithologist |whose labours in this depart- ment are peculiarly valuable and important, of the Family of Anatida*. 29 point, I must refer the reader to the ornithological volume of the « Northern Zoology,' now about to appear, where he will find our peculiar views explained and illustrated. I have, in- deed, chosen to enumerate, in both instances, the subordinate divisions of the aberrant group, but they are always viewed by me as forming a distinct circle of their own, the primary divisions of every natural group being considered as THREE, and not FIVE. In the present instance, the three sub-genera of Chauliodus, Dafila, and Boschas, possess one common cha- racter, in not having the bill conspicuously dilated at its ex- tremity; while their circular succession can hardly be ques- tioned, when we find that the greatest modern reformers * leave the Gadwall and the Mallard in the same group : — these writers having overlooked the modification of the laminae, and passed over the difference in the habits of these birds, as not bearing upon the question. The theory, that the Mallard is the typical representation of this family, has now, I trust, been thoroughly investigated, and demonstrated to be erroneous ; nor can I consider the two circular arrangements f that have been made of the whole family, each apparently perfect, but essentially different, in any other light. They appear to me to be the result of abstract theory, and of a theory completely misapplied. On the other hand, I deem it but justice to the great merits of another orni- thologist of our own country, to acknowledge the assistance I have derived from his highly valuable paper, on the trachasa of birds J, and at the same time to declare that if there is any truth in his own inferences, drawn from internal structure, or in mine, resulting from attention to external form and habits, he has himself marked out the true circle of the Anatidae, so far as the British species are concerned, totally unconscious of having done so. There is, and there cannot be, but one plan of creation. In our efforts to develope this plan, we must, as Mr. Yarrell justly observes, ' combine ascertained habits, ex- ternal characters, and anatomical structure :' and in proportion as we can do this, so may we assume that our arrangement is NATURAL. * Dr. Leach, Dr. Fleming, Stevens, Vigors, f Linn. Trans., *iv, p. 499. Zool. Jour, III. p. 404. J Lion. Trans., xv. p. 378, 30 ON THE RELATION BETWEEN THE POLYHEDRAL AND SPHEROIDAL THEORIES OF CRYSTALLIZATION; AND THE CONNEXION OF THE LATTER WITH THE EXPE- RIMENTS OF PROFESSOR MITSCHERLICH. By J. F. DANIELL, F.R.S., Professor of Chemistry in King's College, London. E Molecular Philosophy, which is the subject of the following paper, is situated on the very confines of human knowledge — on that ill-defined and misty line where the most exalted intellect must be conscious that its powers begin to fail. Towards this debateable region it is, in general, sound discretion in the practical philosopher not to advance too far. Within its confines an ignis fatuus has too often been mis- taken for the light of truth, and high energies have been wasted which might have brought forth substantial fruit on firmer ground. It is for this reason that the professors of the Royal Insti- tution have ever acted most wisely in excluding from their lessons of chemistry the Atomic Doctrine, and have confined themselves to the exposition of the theory of Definite Propor- tions. Had they followed certain illustrious examples, which have not been wanting, of dogmatizing upon the number and weight of ultimate atoms, instead of developing the beautiful relations of chemical equivalents, chemistry, in the place of that captivating simplicity which its aspect now presents in our systems, would have exhibited that kind of pseudo-mathe- matical confusion, which, from this and other analogous causes, too often obscures the doctrines of other justly cele- brated schools. But although this recondite and mental philosophy should not be mingled up with practical science, there is no reason why it may not be studied apart: on the contrary; a more noble exercise for the faculties cannot be conceived than the speculations to which it leads, when bounded by a proper dis- cretion. As science slowly advances we gradually raise our point of sight, and we may reasonably expect that our horizon will consequently extend; and objects, which before were but dimly discerned, will become more distinct, and our judgments Mr. J. F. Daniell on Crystallization. 31 corrected of things in the farthest distance. A more extended view of this description of the ultimate structure of crystalline bodies appears to me to be afforded by the experiments of Professor Mitscherlich upon the expansion of certain bodies by heat ; as an introduction to which, a connected retrospect of the two theories of crystallization, although presenting but little new, will, I trust, not be considered as misplaced. The observation upon which M. Haiiy founded his beautiful theory of the structure of crystals is well known. He took a six-sided prism of calcareous spar, and, in attempting to split it, he found that of the six edges of the superior base, three alter- nate edges only yielded to the blow, and that the division there took place at a certain determinate angle. The three inter- mediate edges resisted this division ; but, in applying the same force to the inferior base of the crystal, the intermediate edges alone yielded. By following up this cleavage in the natural directions thus pointed out, the new-formed planes met toge- ther, and he at length obtained an obtuse rhombohedron of definite angles ; which was further divisible in the direction of faces into, apparently, an infinite number of similar smaller rhombohedrons. To this invariable solid he gave the title of the PRIMITIVE FORM of calcareous spar, and he supposed it to be the form of its ultimate molecules; from aggregations of which, externally modified, according to geometric laws, he conceived all secondary forms of the same substance to be produced. This conclusion seemed to derive much force from the ob- servation, that any crystal of calcareous spar, of whatever form, carefully broken, may always be resolved into an infinitude of small rhombohedrons, and that this form persists to the utmost limit to which we can carry mechanical division. The same observation is applicable to other substances ; but the primitive form is, in many cases, peculiar to the sub- stance examined : thus, for instance, a crystal ofjulphuret of lead is resolvable by mechanical force into a number of small cubes, in the same manner that calcareous spar is resolvable into small rhombohedrons. M. Haiiy calculated the secondary forms of crystals, by decrements of particles taking place on different edges and 32 Mr. J. F. Daniell on Crystallization. angles of the primitive forms. There is no difficulty in con- ceiving a compound cube made up of a large number of small cubes ; but if we place, upon each of the six faces of the cube so formed, layers of cubic particles, decreasing each by a row of particles parallel to the edges, till a pyramid is constructed nipon each, terminating in a single particle, the figure becomes converted into a dodecahedron with twelve equal rhombic sides. If the decrement take place upon the angles, instead of the edges, of the original cube, the figure is converted into an octohedron. By decrements of more than one row of particles, and by intermediate and mixed decrements, it may be shown that an almost infinite variety of secondary forms may be constructed ; any or all of which may be assumed by the substance to which the primitive form belongs. Figures of these various decrements are now so common in elementary works of science, that there is no occasion to present them here. So far our ob- servations upon the mechanical properties of such bodies will go hand in hand with the hypothesis. Parallelopipedons, or six-sided figures, of the nature of the rhombohedron and cube, might attract one another by their similar sides, would form stable combinations, fill all the spaces which they occupy, and would yield to mechanical division only in the direction of their joints. But there is a class of substances, which, affording the same series of secondary crystals as sulphuret of lead, yields to me- chanical division in very different directions ; and affords pri- mitive forms of a very different character. This class of crys- tals is well represented by fluor spar. If we apply the edge of a knife with a little dexterity to a cube of Jiuor spar, we shall find that its eight solid corners may be removed, and that the new-formed planes will coincide with those of a regular octohedron. We may go on separating slices from any of these faces, all of which may be split into acute rhombohedrons. Had observation rested here, no difficulty would have occurred in applying the hypothesis, — the acute rhombohedron would have been the primitive form — and the cube, the octohedron, and all the modifications of this series might readily have been produced by decrements Mr. J. F. Daniell on Crystallization. 33 upon its edges and angles. But this rhombohedron, unlike that of calcareous spar, is not only divisible in directions parallel to its six faces, but may be split into two tetrahedrons and one octohedron, — the four solid angles again, if the two tetrahedrons maybe split off, and two octohedrons will remain ; and the octohedron may be divided into six smaller octohe- drons and eight tetrahedrons. Thus the whole mass may be resolved into tetrahedra and octohedra ; no one of which can we conceive so small as not to be again divisible in a similar manner. Which, then, of these two solids is entitled to be considered the primitive form of the crystal ? Neither of them can fill space without leaving vacuities ; and we can scarcely conceive either of them forming an arrangement sufficiently stable to consti- tute the basis of a permanent crystal. They may both be symmetrically arranged, so as to afford to the eye the external forms of the series of secondary crystals, which may be geometrically calculated from their various decrements ; but they must be conceived to attract one another by their edges only ; and the tetrahedral arrangements will be regularly interspersed with octohedral, and the octohe- dral with tetrahedral cavities. The following figures, which I never yet saw represented in works upon crystallography, exhibit the construction of the tetrahedron, the octohedron, and the cube upon each of these hypotheses. VOL. II. Aua, 1831, 34 Mr. J. F. Daniell on Crystallixation. The tetrahedral arrangement, in fact, represents the cavi- ties in the octohedral construction ; and the octohedral ar- rangement would exactly fill the interstices of the tetrahedral. This appeal to the eye cannot be without its effect in pro- ducing a conviction that such arrangements, although sym- metrical, must be unstable, and that they are contrary to all our ideas of the common powers of attraction in matter. It is so obviously impossible, according to all our experience, that solids of this kind should attract one another by their edges, and not by their sides, that we are compelled to adopt the unphilosophical expedient of recurring to an uncommon and unknown power ; our ignorance of which will be but ill con- cealed, by conferring upon it the name of polarity, or some such indefinite, convenient term. Another observation here occurs, which I never remember to have seen advanced, but which appears to me to be fatal to this hypothesis. M. Haiiy, in this ambiguous choice of a primitive form for fluor spar, and a vast variety of other crys- Mr. J. F. Daniell on Crystallization. 35 talline substances, chose the tetrahedron with octohedral va- cuities, rather than the octohedron with tetrahedral spaces, for reasons which he has assigned. Now, if we refer to the figure of the cube, constructed upon this principle, it will be observed that, if ever there had been a power which could have thus grouped together these particles, mechanical force would have split the solid in directions parallel to the faces of the cube, and not parallel to the faces of an octohedron ; for in such an arrangement each particle is in contact with one other par- ticle, while in the second each is engaged by three; so that the force of attraction must be greater in the latter than in the former. We thus, in fact, demolish the foundation upon which the whole superstructure is founded. Dr. Wollaston * proposed to obviate the difficulty of the in- tersticial vacuities in these tetrahedral and octohedral arrange- ments, in a most ingenious manner. He suggested that the whole difficulty would vanish, by considering the elementary particles to be perfect spheres, and to assume that arrangement which would bring them as near to each other as possible. The relative position of any number of equal balls in the same plane when gently pressed together, forming equilateral triangles with each other, is familiar to every one ; and it is evident that if balls so placed were cemented together, and the stratum thus formed were afterwards broken, the straight lines in which they would be disposed to separate would form angles of 60° with each other. If a single ball were placed at rest upon such stratum, it would be in contact with three of the lower balls ; and the lines joining the centres of four balls, so in contact, or the planes touching their surfaces, would include a regular tetrahedron having all its sides equilateral triangles. The construction of the acute rhombohedron and octohe- dron, on the same principle's as simple as that of the tetrahe- dron ; and the following figures will illustrate the simplicity and stability of the arrangement, and its perfect harmony with the known laws of attraction, both in its construction and the directions in which it would be disposed to yield to mechanical force. » Phil. Trans. 1813. D2 36 Mr. J. F, Daniell on Crystallization. Dr. Wollaston next proceeded to inquire what forms would probably occur from the union of other solids most nearly allied to the sphere ; and he showed that, by supposing the elemen- tary particles to be spheroidical, many solids might be con- structed which are well known to crystallographers. By imagining the axis of the elementary spheroid to be its shortest dimension, a numerous class of well-known solids originate. By grouping together oblate spheroids, in the same manner as the spheres in the formation of the acute rhombo- hedron, the resulting figure will still be a rhombohedron ; but the measure of its angles will be different, and will be more or less obtuse according to the degree of oblateness of the original spheroid. If the proportion of the axis be as 1 to 2.87, the rhombohedron will be that of calcareous spar. If the degree of oblateness were as 1 to 2, a right-angled rhombohedron or cube would result. These solids would obviously be split, by mechanical force, in directions parallel to their faces. If the elementary spheroid on the contrary were oblong in- stead of oblate, it is evident that by mutual attraction their cen- tres would approach nearest to each other when their axes are Mr. J. F. Daniell on Crystallization. 37 parallel, and their shortest diameters in the same plane. The manifest consequence of this structure would be, that a solid so formed would be liable to split into plates at right angles to its axis, and the plates would divide into prisms of three or six sides, with all their angles equal ; as occurs in phosphate of lime, beryl, &c. It is, however, a very singular circumstance, that the con- struction of the cube with spheres, upon the same principle as the octohedron and the other solids of that series, escaped the ingenious author of this hypothesis — a failure which, had it been essential, instead of accidental, would have rendered it as untenable as that whose defects it was intended to supply. Dr. Wollaston was perfectly aware that the hypothesis must have appeared defective, if it had not included some view of the manner in which so simple a form might originate ; the only mode which occurred to him of supplying this desidera- tum was, to imagine a mass of matter to consist of spherical particles, all of the same size, but of two different kinds, in equal numbers, represented by black and white balls : these, he suggested, might be arranged four and four above each other, as in the following figure, alternately black and white throughout : the distances of the centres of the black balls, being every way a superficial diagonal of the cube, are equidistant, and their con- figuration represents a regular tetrahedron ; and the same is the relative position of the four white balls. Every black ball is thus equally distant from all surrounding white balls, and all adjacent balls of the same denomination are also equidistant from each other, and the whole might be conceived to be in equilibrio. The experimental part of the investigation had hitherto been confined to the action of mechanical force ; by the application 38 Mr, J. F. Daniell on Crystallization. of which it was found that crystalline bodies may be cloven in certain determinate and constant directions, from which the planes of least resistance in the solid are easily determined ; but this is not the only force by which their structure may be dissected. The lower degrees of chemical affinity may be applied, as I have formerly shown, (Journal of the Royal Institution, vol. i. p. 24,) more delicately to the same purpose. An irregular mass of alum, which, although to the eye it exhibits no traces of crystalline arrangement, may easily be shown to possess as regular a structure as the best defined crystal of the same substance. Mechanical force will not avail us for this purpose, as regular cleavages cannot be detected in it; but if we expose it to the solvent power of water, at first the fluid acts upon the salt with so much energy as to overcome the cohesion of the solid in every direction alike ; but, as the water becomes saturated, its power diminishes, and it is nearly balanced by that delicate modification of cohesion upon which crystalline structure depends. The consequence is, that the solid now yields to the solvent only in the points of least resistance, and the mass will present the form of octo- hedrons and sections of octohedrons, as it were, carved or stamped upon its surface. The numerous forms which are thus dissected from the mass are arranged in a definite order, with regard to each other and the different faces of the mass ; and the series which occur upon one face, and those which correspond with it, are never intermingled upon dissimilar faces. Thus in one direction the light will be reflected from the faces of octohedrons and sec- tions of octohedrons all upon the same plane ; and by turning the mass upon its axis, the same will be repeated at every quadrant of a circle. By gently inclining the mass, the re- flection will next arise from right-angled parallelograms of every dimension, which are similarly repeated upon turning the mass upon its axis. Now, by supposing the process of solution continued till the several planes intersected each other, it is clear that various modifications of the octohedron and cube would result, all necessarily referable to the same structure of particles in the original mass : and it is obvious that each of the almost infinite Mr. J. F. Daniell on Crystallization. 39 external variety of solids which would be produced by the meet- ing together of the various facets thus presented to the eye must be derivable from one principle of internal arrangement. The octahedron therefore and the cube could not depend, in this instance, upon such opposite constructions as those represented in Dr. Wollaston's hypothesis. But we are not on this ac- count driven to abandon the spherical atoms, for, however singular it may appear that this eminent philosopher should have overlooked the fact, the cube may easily be shown to be derivable from a structure precisely analogous to the octo- hedron, the tetrahedron, and the acute rhombohedron. It has been already shown that by placing a sphere upon two opposite faces of an octohedron, we convert the solid into the latter figure: by placing one upon each face, it is as simply converted into a cube as in the following figure. Now, such a cube would obviously be divisible by mechanical force in directions parallel to the faces of the octohedron ; because in those directions each particle is held by the attrac- tion of three others only; while in the transverse direction each is engaged by four others; and this is the direction in which fluor spar yields. But now another difficulty occurs — this may be supposed to be a satisfactory account of the con- struction of the cube with octohedral cleavages, but how shall we explain the octohedron of sulphuret of lead, which splits into cubic fragments ? This is one of a numerous class of sub- stances exhibiting the same phenomenon of the cubic fracture with the same series of crystals as fluor spar and others of the octohedral class. The theory will be worth little if it should be found applicable only to the latter. If we suppose ten spheres endued with equal powers of attraction simultaneously exerting their powers upon each other, their forces would be most equally balanced in the cubic form, producing the compact and stable arrangemen 40 Mr. J. F. Daniell on Crystallization. represented in the last figure. If, from some predisposition of affinity, the particles of any solution should continue to com- bine in this definite proportion, a number of cubes would be formed ; which, again attracting one another, would unite toge- ther side by side, according to the general laws which we have observed. A compound cube would be thus naturally con- structed, and it is evident that mechanical force would resolve such a solid into a number of smaller cubes ; for upon the planes of junction the spheres of one cube are only held to the spheres of another cube by the binary attraction of two par- ticles for each other, while in every other direction each ball is in contact with three others at least. Now, the first simple cube may be resolved into two similar, but irregular tetrahedrons ; and if we suppose an octohedron formed by a decrement upon the angles of the cube analogous to that in M. Haiiy's cubic system, these tetrahedrons would exactly fill the intersticial spaces ; and an octohedral arrange- ment would be formed with precisely the same angles as the constructions which we have previously considered, but which would exhibit the phenomena of the cubic instead of the octo- hedral cleavage. Mr. J. F. Daniell on Crystallization. 41 It would be easy to show how all the regular solids of the octohedral series, and their modifications, might be produced by either of these principles of arrangement ; but enough has been premised to introduce the additional argument in favour of the spheroidical hypothesis of crystallization, which may, I think, be unexpectedly derived from the experiments of Pro- fessor Mitscherlich. We have hitherto considered the arrangement of our atoms as due solely to their mutual powers of attraction — let us now contemplate it as the result of a balance of the attractive power of the atoms, and of the repulsive power of an elastic atmosphere, with which we may conceive each to be sur- rounded, and which will represent the repulsive power of heat. The atoms we suppose attractive of each other and of the par- ticles of the hypothetical atmosphere, but the latter highly repulsive of each other. Upon these postulates, each spherical atom would be surrounded by a stratum of equal depth in all its parts, uniformly distributed over its surface ; which, preventing the actual contact of the particles, would nevertheless allow them to arrange themselves according to the laws of the predominant attraction. We may suppose the figure a to represent a section of the tetrahedral arrangement of spheres in simple contact ; and the figure b of the same spheres with their atmospheres ; an arrangement essentially the same with regard to structure and external figure. Any addition or diminution of the repulsive aura would cause the atoms to recede from or approach towards each other equally ; and if we were to heat a solid so constructed, it would expand equally in all directions. But what would be the case with the structure of oblate spheroids, instead of spheres ? In the first place, as the force of their attraction must, from 42 Mr. J. F. Daniell on Crystallization, the nature of their form, be exerted with greater force in the direction of their shorter axis than in that of their longer,— taking for granted the two fundamental laws of attraction, first, that all the particles of matter attract one another directly as their masses, and inversely as the squares of their distances : secondly, that a body of any shape will attract a particle of matter anywhere with the same force, and in the same direc- tion, as if all the matter of the body were collected in its centre of gravity, — it is clear that their repulsive atmospheres will not be distributed in equal layers over their surfaces ; but will collect in greater depth above the shorter axis than the longer ; and the atom, with its atmosphere, will assume more pf the spheric form. A solid crystal, therefore, thus constructed, must change the measure of its angles with every change of temperature. This is precisely what Professor Mitscherlich has ascertained to happen with crystals of carbonate of lime and other substances not crystallizing in the octohedral series. He found that a rhombohedron of calcareous spar changed the inclination of its planes to the amount of 8'. 5 in the inter- val between 32 and 212. As the temperature augmented, the obtuse angles diminished ; that is, the smaller axis of the rhombohedron dilated more than its other diagonals, so as to cause an approach to the cubic form. In substances crystallizing in the octohedral series, he found that the expansion was equal in all directions. The mere inspection of the rhombohedron, made to represent the primitive form of carbonate of lime, upon the spheroidical hypothesis, is almost enough to produce a conviction that it must expand and contract differently in the directions of its two axes ; and the theory might certainly have had the advantage of anticipating an observation which tends so powerfully to its support. A new and interesting field of research has thus been opened by this third method of disturbing crystalline cohesion, which Mr. J. F. Daniell on Crystallization. 43 cannot fail of proving fertile of important consequences to the corpuscular philosophy. There is a great and natural reluctance in the mind to give up an hypothesis ingeniously constructed, like that of M. Haiiy, so as not only to present in a general point of view a great number of particular facts, but to enable us to reason from the known to the unknown, and actually to predict facts before trial ; and it is from this cause, I think, that the sphe- roidal view of crystallization has not hitherto received all that consideration which it appears to me to deserve. It is, however, by no means uncommon in physics to find two theories maintained as to the origin of natural phenomena, both of which cannot of course be the real laws of nature, but each of which will enable us to generalize and group the facts together with accuracy. I need only refer to the two theories of electrical phenomena and the two theories of heat. When two hypotheses thus run parallel to each other, and each explains a great many facts in common with the other, such unforeseen evidence in favour of one, as I have been endeavouring to explain, is of the utmost consequence. But it is of scarcely less importance to show, if possible, the con- nexion of one with the other, which enables them to apply to so many circumstances in common. Now it appears to me that this is not difficult with regard to the two theories of crystallization. Those who have attentively studied the great work of M. Haiiy must be well aware that he could not have been insen- sible to the difficulties which attended his system, when viewed as an account of the real process of nature ; but, whilst in doubt with regard to this ultimate object of inquiry, he most philosophically adopted a temporary substitute for truth, which was capable of leading him by legitimate reasonings to conclu- sions in exact accordance with observations so numerous as fairly to embrace the whole range of phenomena which the theory was intended to account for. The fact is, that, so far from insisting on the real existence of his primitive forms and integrant molecules, as many of his followers injudiciously have done, he very early in his reason- ing points out the difficulty of the ambiguous choice, and of the vacant interstices j and shows that the whole purpose of 44 Mr. J. F. Daniell on Crystallization. his calculations is answered by imagining the primitive form in all instances the parallelopipedons (or six-sided figures), which would result from the addition of the vacant spaces to the molecules. To such imaginary forms he gives the name of substractive molecules, and he observes that ' the theory would not fail of attaining its principal object, if it were to stop at the parallelo- pipedons which the mechanical division of crystals first affords ; and the species of anatomy which these parallelopipedons undergo, when we attempt to ascend to the true form of the integrant molecule, is an ulterior step, without which observa- tion, rather than theory, would leave something to be desired. The parallelopipedon here represents the unity to which all the results of the theory may be referred ; and it matters little whether or not, beyond this unity, there may be fractions formed of its subdivisions*.' With regard to the crystals which derive their origin from the octohedron or tetrahedron, he remarks, * We may consider the decrements which give rise to these forms as taking place by one or more rows of small rhombohedrons, with angles of 120° and 60°. Whether the solid parts of these rhombohedrons be octohedrons, which leave between each other vacuities of the form of tetrahedrons, or whether the contrary be the case, is perfectly indifferent to the theory, which considers here nothing but the rhomboidal spaces, abstracted from the small bodies which occupy those spaces^.' Now, the spheroidical hypothesis shows how these abstract geometrical spaces may be filled up more completely, and with a greater regard to the known laws of attraction, than by the method which suggested itself to the mind of the immortal author of the * Treatise on Mineralogy,' the primary object of whose system is not affected by the change. The calculations founded upon his imaginary substractive particles will still furnish the key to the different series of secondary forms ; and we establish, rather than upset, them by showing that they may be referred to a system of attractions which, when tested by the antagonist powers of heat, chemical affinity, and me- chanical force, is found consistent with the observed pheno- mena in every particular. * Hiiliy, Trait6 de JVUjieralogie, tome I, p. 97. f Ibid., p, 473. 45 ON THE ILLUMINATION OF THEATRES. By ALFRED AINGER, Esq. rPHE important rank which dramatic representations have ' ever held among the amusements of all civilized people gives an interest to everything connected with the improve- ment of even their most subordinate auxiliaries. I have ima- gined, therefore, that an investigation of the existing methods of illuminating theatres, and a proposition for remedying some of their defects, may not be thought unworthy of a place in a scientific journal. The first, and this is perhaps the most trifling objection to the present system, is, that it is obviously artificial. Although, ninety-nine times out of a hundred, the scene is supposed to be exhibited by natural light, — that of the sun or moon, — the greater part of the light which reaches the spectator is visibly derived from lamps or candles, which are so conspicuously and variously situated, as of necessity to come more or less within his angle of vision. By this means, not only is the illusion of the scene very much diminished, but its force and vividness, considered as a mere picture, are greatly impaired by the superior intensity of numerous radiating points, which over- power the light merely reflected from the actors and the scenery. A similar injury is occasioned by the unpleasant flickering of the foot-lamps above their screens, and by the excessive light they give to the highly-decorated proscenium, which thus becomes a brilliant and sparkling frame to a com- paratively dull picture. The effect is something like what might be produced by hanging variegated lamps round the edges of a painting ; and, if avoidable, is scarcely more judi- cious. The amazing force of the dioramic pictures is mainly owing to the adoption of an opposite course — that of subduing, as much as possible, everything extraneous to the ostensible objects. The central chandeliers, which have been introduced within a few years, produce, to a certain extent, the same sort of mischief, by the powerful light thrown on the ceilings, to which they are of necessity very near, that they may not inter- fere with the view of the upper spectators. This proximity of the ceiling to the chandelier, and its consequent lightness, are further objectionable, because the first causes the decorations 46 Mr. Ainger on the Illumination of Theatres. to be quickly covered with soot, and the second renders it visible ; so that this part of the theatre becomes disgust- ingly dirty before the remainder is sensibly soiled. Nor can this be guarded against by the use of glass chimneys to im- prove the combustion of the gas, because they would be too inaccessible to be cleaned, and they would moreover be pro- ductive of danger to the frequenters of the pit. In addition to the smoking and flickering of the foot-lamps, immediately between the spectator and the scene, they injure the sight by the currents of unequally heated air which they interpose, and which, by irregularly refracting the light, give a wavy and disagreeable appearance to whatever is seen through them. The effect of these lights on the performers is rendered evident by the obviously constrained aversion of their eyes, while the expression of the features is almost destroyed by the reversal of the shadows under which the face is usually and best seen. The figure suffers as much as the face from this inversion; and it becomes peculiarly inappropriate when viewed in conjunction with a scene where the shadows are evidently derived from a superior light. A further objection to all the lights is, that being in sight of the audience, they cannot conveniently receive those atten- tions which it would occasionally be useful to bestow on them, and also that their combustion is rendered imperfect by the impurity and agitation of the atmosphere about them. Their immense consumption of air adds materially to the draughts, which too frequently prove prejudicial to the health of delicate visiters to the theatre ; and the velocity which they lend to the general upward current through the roof, together with the rarefaction and impurity they impart to it, must interfere considerably with the transmission of sounds from the stage to that part of the audience which is below or but little above its level. The mode of illumination which I am about to suggest will, if practicable at all, remove the whole of the objections I have enumerated. It will be sensible to the audience only through its indirect and intended effect, and it will give appropriate shadows to the performers. The light may be obtained under the best circumstances for securing good combustion ; the Mr. Ainger on the Illumination of Theatres* 47 flames may be supplied with a steady current of pure air ; they will therefore burn with little smoke, and neither air nor smoke will ever in any way become obnoxious to the audience. The house may thus be preserved well ventilated and clean, while the lights, by their perfect combustion, will be rendered eco- nomical, and still more so by the opportunity of using appro- priate reflectors to direct the rays towards the points at which they are required. It is not an exaggeration to say that four- fifths of the light at present employed are wasted in conse- quence of radiation in worse than useless directions, or of absorption (to use the common term) by imperfectly reflecting surfaces. I propose to remove the foot-lamps and the central chande- lier, together with all the smaller lights round the circumference of the house, and to substitute an illuminated dome, as shown (in the plate) in section, fig. 1, and in plan, fig. 2. This dome would, at its lower part, be formed into circular or octagonal panels, the frames of which might be enriched and gilt, but the panels themselves would be occupied by glass, behind which would be lights of greater or less power, and to each a reflector equal in diameter to the panel, and of greater or less perfec- tion in regard both to form and materials. In the drawing I have described three tiers of circular panels, each containing thirty-six, or in the whole one hundred and eight. To the quadrant immediately opposite the stage, or from C to C in figure 2, containing twenty-seven panels, I should apply the most powerful gas-lights* I could obtain, and the most perfect parabolic reflectors. Their axes would be in radii of the dome, which would be made such a segment of a sphere, that those radii would point precisely to those parts of the stage where the light was required. It may be thought that light so directed would be too concentrated, or, in the language of artists, spotty ; but as the reflectors would not average more than eighteen inches in diameter, and the flames would have considerable magnitude, so much of the source of light would be ex-focal, that each parabola would supply a cone of rays sufficiently obtuse to mingle with those * If it be desirable to employ the light of lime burning in oxy-hydrogen gas, such an arrangement us is here proposed seems peculiarly adapted to the purpose. 48 Mr. Ainger on the Illumination of Theatre^. of the adjacent reflectors, and blend the whole into one undis- tinguishable mass. If, for example, an eighteen-inch parabola be generated, having the distance between the vertex and focus three inches, and if the diameter of the flame in that focus be upwards of an inch, the cone of rays issuing from such a reflector will have at its apex an angle of more than twenty degrees. The light thus thrown on the performers would, I think, be greater than could be obtained from twenty- seven equal flames in the situation of the foot-lamps ; for, if lines be drawn from the place of the foot-lights to the average position of the actors, it will be evident how extremely small a sector of the sphere of rays proceeds in an available direction ; while, in the proposed arrangement, nearly every ray, with only so much loss as is occasioned by the imperfection of the reflecting surface, would be directed exactly to the required points. The panels in the remaining three quadrants might be sup- plied with inferior lights and reflectors ; and the glass would be ground, to diffuse the light over the house, and to improve the appearance of the dome when seen by the audience. The change from the ground to the unground glass would be visible only to a small part of the house ; and though, as far as it goes, it would be a defect, it is not, I think, to be put in competition with its numerous and important advantages. It is not, indeed, impossible that the light would be found sufficiently strong to allow of the glass from C to C being slightly ground, by which every objection would be obviated. If this be not practicable, the defect would be seen only when expressly looked for, and would be merely a slight exaggera- tion of the effect which would be produced upon a similar dome exposed to the sun's rays, which might be nearly verti- cal on the one side, and wholly excluded from the other. The variations of light required upon the stage would be managed with much greater beauty and effect, than when a rising or setting sun is seen to be accompanied by the rising or sinking and smoking of a hundred artificial flames. It will, perhaps, be doubted whether a light, such as I have described, would extend over a sufficient portion of the stage: such a doubt will exist only with those who are unaware how Mr. Ainger on the Illumination of Theatres. 49 small a part of the light on the stage is derived from the foot- lamps. Whenever the performer is behind the line A A on the plan, he is lighted principally from the lamps which are numerous and powerful immediately behind the proscenium, at the points A A ; from these also, and from similar lights concealed behind the side-scenes, the scenery obtains nearly all its light, receiving so little assistance from the foot-lamps, that I have the authority of one of the most eminent scene- painters for saying, that if sufficient light can be obtained for the performers, there would be no difficulty in regard to the scenery. I have given all the reasons which occur to me for thinking that it would be sufficient in quantity ; and its average direction is indicated by the sword in the hand of the figure drawn on the section. I have, therefore, no doubt that there would be very little difficulty in realizing the whole of the plan ; and that, if real- ized, the result would be to add much to the comfort, conve- nience, and splendour of theatres — to give infinitely greater effect to the scene — and to do justice to the features and ex- pression of the performers. [See Note at the end of the Miscellanea.] ON THE RED SOLUTIONS OF MANGANESE, BY THOMAS J. PEARSALL, Chemical Assistant in the Royal Institution. HP HE crimson solutions obtained by the action of certain acids upon oxides of manganese, possess some remarkable properties, which have received only partial and unsatisfactory explanations. It has been hitherto supposed that an oxide of manganese existed, which was capable of dissolving in acids, to produce pink or deep red coloured solutions, but the precise state of oxidizement has not been agreed upon. The red oxide, deutoxide, and peroxide have each been selected as the one present*. In consequence of experiments which I have made to dis- • Gay Lussac, Annales de Chiraie, i. p. 39. Berzelius, Traiie de Chimie iii p. '298. Thenard, Traite de Chimie, 5th edit., iii. p. 184. Turner's Elements of Chemistry, 2nd edit., pp. 471, 475. Thomson's First Principles of Chemistry. VOL. II. AUG. 1831. E 50 Mr. T. J. Pearsall on the cover the cause of the colour, and the other properties of the red solutions of manganese, I am led to believe that they are not due to the presence of an oxide, but to manganesic acid, which has not hitherto been suspected *. These solutions are always strongly acid; they do not cry- stallize or form definite salts ; the colours and tints are rapidly destroyed by deoxidizing agents, and the concentrated solutions, especially if obtained by means of sulphuric acid, are readily decomposed by mere dilution with water. The solutions have a peculiar odour, and exert strong bleaching powers, which effects have been supposed due to the presence of foreign bodies, rather than to the state of the manganese existing in the solutions. It was necessary, therefore, at first, to ascertain whether these are constant properties of acid red solutions of manganese, or whether they are owing, as supposed, to the action of chlorine derived from accidental sources. Black oxide of manganese was repeatedly washed with hot distilled water, which gave no trace of muriatic acid when tested by nitrate of silver ; then oil of vitriol, free from muriatic acid, was diluted with its weight of water and poured upon the oxide. In twenty-four hours the fluid had assumed a crimson colour, and after several weeks a very deep crimson solution was obtained, which, when diluted, produced no turbidness with nitrate of silver. A dilute solution of sulphate of indigo was powerfully bleached by this red fluid, and a stronger solution of indigo had its colour instantly destroyed, leaving only an amber tint. These bleached portions of fluid gave not the least indication of chlorine when tested; but a solution of indigo bleached by chlorine gave a precipitate with nitrate of silver. • Part of this red solution was introduced into a retort, the neck of which was dipped into a solution of sulphate of indigo, and the retort heated by a spirit-lamp ; the indigo was not bleached, neither was there any trace of the odour of chlorine ; the ope- ration was continued until part of the contents of the retort had distilled over, the temperature having been raised to about 400°. The retort was then heated with the neck immersed in a solution of nitrate of silver, in which no cloudiness occurred, * Brande's Manual of Chemistry, 3d edit., ii. p, 6, Red Solutions of Manganese. 51 and the fluid in the retort still strongly bleached indigo ; but •when a small portion of solution of chlorine was added to the same crimson fluid, or to colourless protosulphate of manga- nese, and then heated in the same manner, chlorine was driven over, and rapidly bleached the blue liquor. If chlorine, there- fore, had been present in the previous experiments, it would have been rendered evident by this arrangement. In other experiments the crimson sulphuric acid solution was decomposed by being much diluted with water, the oxide separated by filtration, and the clear liquor distilled ; half the fluid, however, passed over into the indigo without effecting any bleaching change, nor did the liquor in the retort bleach : if chlorine had been present in the solution, it would have remained after dilution. Then pure hydrated protoxide of manganese, which had be- come brown by exposure to the air, was mixed with sulphuric acid, and a red fluid was obtained which possessed bleaching properties, but which, when diluted with water or heated with alcohol, lost all colour and all bleaching power : hence there is no evidence that chlorine is the bleaching agent; on the con- trary, the bleaching power of the sulphuric solutions accompa- nies the coloured state of manganese, and it appears that these two properties are present or absent together. As the red sulphuric solution appears to have been the only one referred to with regard to this power, I proceeded to examine whether other red solutions of manganese possessed similar properties. In the process of triturating together binoxalate of potassa and peroxide of manganese, pointed out by Van Mons*, a crimson fluid is produced of great depth of colour; it is acid, and becomes colourless after some time, depositing crystals. I found that while red it bleached indigo very strongly, the action being accelerated by the addition of sulphuric acid. This crimson solution lost its colour when heated in a retort; carbonic acid gas was evolved, which bubbled through the solution of indigo, without altering it, and the fluid in the retort, now clear and colourless, had lost its bleaching power. * Quarterly Journal of Science, ix. 409. E 2 52 Mr. T. J. Pearsall on the When nitrate of silver was added to this crimson solution, an abundant white precipitate of oxalate of silver was pro- duced, which was readily soluble in diluted nitric acid, and thus easily distinguished from the chloride of silver, for which it might be mistaken from its similar appearance ; more espe- cially as the oxalate, like the chloride of silver, is soluble in pure ammonia. Hence it appears that these red solutions possessed bleach- ing powers in consequence of the peculiar state of manganese, and independent of chlorine *. When pink or crimson solutions of manganese, supposed to contain red, deut, or peroxide, were compared with solutions known to contain manganesic acid, their similarity in some properties was so striking, that I was induced to suspect that manganesic acid alone ought to be regarded as the cause of the peculiar effects. 1. The varieties of scarlet, crimson, or purple colours belonging to manganesic acid, in different circumstances, may be imitated by those from sulphuric acid and oxides of man- ganese. 2. The red solutions of oxides are always very acid; manganesic acid is soluble and compatible with acids. 3. The red solutions by oxides and sulphuric acid bleach ; manganesic and sulphuric acids, mixed, also bleach very strongly. 4. The crimson solution by the action of bin- oxalates upon oxides of manganese bleaches indigo ; man- ganesate of potassa with binoxalates also does the same. 5. Both kinds of solutions are alike rendered colourless by the same deoxidizing agents. 6. Both kinds of solutions are subject to decomposition by mere dilution with water. 7. The sulphuric solution evolves a peculiar odour ; manga- nesic acid in vapour has a similar odour. 8. The addition of certain metallic salts to the supposed solutions of oxides, and also to solutions holding manganesic acid, give similar appear- ances ; and indeed the similarity of the two sets of compared * Mac Mullen on the Native Black Oxide of Manganese — Quarterly Journal of Science, xxii. 233, xxiv. 261. Phillip's Observations on Mac Mullen — Annals of Phil., and Phil. Mag. N. S.,i., 313. F. W. Johnstone on the Evolution of Chlorine from the artificial Oxides of Manganese — Quarterly Journal of Science, xxv. p. 154. Kane on Existence of Chlorine in Peroxide of Manganese, Ibid., p. 286. Red Solutions of Manganese. 53 solutions is so great as to offer the highest probability that their powers depend upon a common cause. It will now be my endeavour to place clearly the experi- mental reasoning which supports this new view of these solu- tions; and, as the bleaching properties of the ordinary red solutions has been first brought into consideration, I will show that the same effects maybe produced by manganesic acid under the same circumstances. A solution of manganesic acid in sulphuric acid was mode- rately heated in a retort ; the portion distilled over did not bleach, but the fluid, still red, bleached indigo instantly. If much sulphuric acid be present, the mixture may in this expe- riment be heated for some time, and sustain an elevated tem- perature before the separation of oxide. Sulphuric acid was added to chamelion mineral, and pro- duced a deep crimson solution of the red manganesate of potassa, that instantly bleached a strong solution of indigo. This red fluid heated in a retort evolved volatile matter, which destroyed the blue colour ; but there was no trace of chlorine in the bleached portions of indigo when tested by nitrate of silver. These experiments with the sulphuric acid fluids containing manganesic acid, prove that this state of manganese produces the same results as the crimson solution. That the sulphuric aeid was not essential to these effects was thus shown : by dis- solving mineral chamelion in water it gave a deep green solu- tion, which, when boiled, became deep red, and then bleached sulphate of indigo ; the resulting fluid was unchanged by nitrate of silver : an aqueous solution of manganesic acid pro- duced the same effect. The crimson solution obtained by the alkaline binoxalate and oxides of manganese is the only other particularly pointed out as supposed to contain the deutoxide of manganese ; although acid, it is not so strongly acid as the sulphuric fluid : on adding oxalic acid or binoxalate of potassa to solution of green chamelion, the rich colours of manganesic acid ap- peared. This deep crimson solution is almost identical in colour with the solution in the former oxalic experiment, and, like it, also bleaches indigo. 54 Mr. T. J. Pearsall on the Solutions of green chamelion and binoxalate of potassa were heated in a retort ; the fluid soon became colourless, but with- out changing the dilute solution of sulphate of indigo into which the neck of the retort was introduced : the colourless fluid was incapable of affecting indigo. Manganesic acid, mixed with oxalic acid, very powerfully bleached indigb : neither oxalic acid nor the binoxalates have any bleaching power over indigo, but manganesic acid and some of its combinations possess this property. The colourless oxalate of potassa and manganese, which remained in the retort after distillation, was rendered acid by sulphuric and oxalic acids ; and then, upon the addition of manganesic acid, a clear red solution was formed, which had strong bleaching powers ; but it lost this property upon becom- ing colourless, which it did in a short time. A very concen- trated solution of red manganesate of potassa was added to another portion of the same colourless triple oxalate ; the red colour was more permanent, and the bleaching still more energetic, than in the preceding experiments. These cases afford experimental evidence that manganesic acid is capa- ble of reproducing the characteristic properties of a crimson solution supposed to contain a deutoxide. I shall now submit that the known properties of manganesic acid and protoxide of manganese are capable of explaining the action of acids upon the various oxides of this metal. The ex- istence of either the red, deut, or peroxide in these fluids appears to me to be an assumption : — of course, the protoxide must always be considered as present, according to the usual reason- ing upon the relations of oxides to acids. The admitted action of sulphuric acid upon peroxide is to form the protoxide, and thus leaves the formation of the red solution by either the red or the deutoxide quite unaccounted for; therefore it may be advantageous to examine the changes which may be sup- posed, in order to produce either of these oxides ; and, 1st, it may be assumed, that the acid reduces the whole of the per- oxide acted upon to the state of red oxide, or deutoxide which forms a red solution ; or, 2dly, the acid reduces part of the per- oxide to the state of protoxide, and another part to the state of red or deutoxide, and both are in solution together ; or, Red Solutions of Manganese. 55 3dly, the formation of these oxides may be accounted for by supposing the peroxide reduced to protoxide, portions of which become again oxidized by oxygen evolved from other portions of peroxide. Since the affinities of these oxides are admitted to be so much inferior to the protoxide, which, with acids, produces definite and permanent compounds, it is not to be expected, therefore, that either the red or the deutoxide should alone be produced ; and in the second, which is the simplest case of the action of sulphuric acid, where, by the loss of one proportional of oxygen, a protoxide is produced to form the constant base of the sulphate, there is no reason to suppose that another oxide should be formed at the same time, and held in solution by the same acid, but with which it is admitted that it cannot form salts; on the third view, the effect of additional oxygen, combining with the protoxide, would be to produce another oxide, acknowledged to have much less affinity for the acid than the protoxide, which, in fact, is to suppose that a weaker could subvert a stronger affinity, and that the feeble indefinite combination resulting (so feeble that even water can destroy it) could hold the place of a strong, definite, and neutral compound with the same acid. Even admitting that protoxide of manganese could combine with oxygen to form a coloured state, this notion would certainly be in favour of manganesic acid. So I suppose that protoxide is present in the red solutions; and it will presently appear that manganesic acid and protoxide may be in solution together. On the supposition heretofore entertained, that an oxide is the cause of colour in the red fluids, it has not been stated whether this oxide be alone or with protoxide ; but it has been admitted that when a red solution by decomposition precipitates a dark oxide, that much protoxide remains behind in solution *. Then this precipitate evidently does not contain the whole, or the same proportion of metal and oxygen which existed in the red solution. It has also been considered that the colour was due to the oxide thrown down ; and as no mode has ever been pointed out for separating protoxide only, it fol- lows, that when the manganese is precipitated from a crimson * ' 3 grains of peroxide were precipitated, and after the action of water potash threw down 27 grains of oxide.'— Phillips, Phil. Mag., N, S.; v, 216. 56 Mr. T. J. Pearsall on the solution by an alkali, it will consist of the mixed states in previous solution ; and hence, because a brown or red oxide may be thus obtained, it cannot be admitted as a proof that this is the same state which existed in the solution ; and, on the contrary, the same precipitated oxide when dissolved by acids being resolved into the same states as before, therefore a crimson fluid obtained from a red or brown oxide is, in itself, no proof that the same oxygenated state of manganese is taken into solution which was acted upon by the acid ; so that there seems no satisfactory evidence of either the red, deut, or the peroxide in the crimson solutions of manganese. The con- stant presence of either the red or deut oxides seems irrecon- cilable with the fact, that every degree of oxidizement higher than the protoxide will afford red solutions ; this, however, agrees with the production of manganesic acid. It has often been remarked as a singular circumstance, that so small a quantity of the red or deutoxide should be capable of causing deep tints * ; but these observations will accord with the fact, that a minute portion of manganesic acid can produce intense colour. The experimental formation and the theoretical composition of manganesic acid afford arguments in favour of its presence in the ordinary red solutions. Dr. Forchammer f first separated this acid from bases ; the pro- cess which he employed consisted in precipitating a solution of green chamelion by nitrate of lead: he describes the dark brown precipitate as a mixture of peroxide of lead and deutoxide of manganese, which, by digestion with sulphuric acid, formed sulphate of protoxide of lead, while the oxygen given off united to the deutoxide of manganese to form man- ganesic acid ; here there is a mixture of oxides, one of which is resolved into protoxide. Now, if we substitute peroxide of manganese in the place of peroxide of lead, then, by analogy, the action of sulphuric acid is, as before, to resolve peroxide into protoxide, while the oxygen given off unites to the deutoxide to form manganesic acid ; and upon this view the changes may be expressed as follow : each proportional of per- oxide by the action of sulphuric acid loses one proportional * Dr. Turner, Phil. Mag., iv. 31 ; and Phillips, Phil. Mag., N, S., v. 216, f 4«wal$ of Philosophy, xvi, p. 133. Red Solutions of Manganese. 57 of oxygen to become protoxide, whilst two proportionals of oxygen so evolved unite with one proportional of peroxide and constitute manganesic acid, which instantly assumes an inde- pendent existence in the acid solution. I have mentioned that the tints are not constantly the same : when oil of vitriol acts upon peroxide of manganese in the cold, the colour, at first pink, becomes ultimately deep crim- son ; a rich scarlet fluid is formed when sulphuric acid acts upon hydrated brown oxides ; and I have also observed, where excess of oxide has been employed, that the subsequent addi- tions of acid were paler and pinkish tinted. If strong oil of vitriol be added to the deep crimson solution, the colour changes to pink or to violet, bordering upon purple : on con- centrating the same deep red solution by heat, it changes to a pink tint. These variations are enumerated to show that no arguments can be raised against manganesic acid on the point of colour : for these colours are identical with those exhibited by manganesic acid and manganesates under different circum- stances. Assuming that manganesic acid gave colour to the red sulphuric acid, then the addition of manganesic acid should increase the colour and other properties ; and it was found that manganesic acid added to pink sulphuric acid decanted from an oxide, immediately heightened the brilliant pink tint, giving deep colour without any other change. After the fluid had been kept three months in a stopped bottle, the pink colour still remained stronger than that of the acid originally employed. The red manganesate of potassa, with sulphuric acid, was also mixed with another portion of the same solution ; the colour was increased to crimson ; and although oxide of manganese was deposited upon the glass after some days, the tint still remaining was stronger than that of the acid in contact with oxides. A portion of the red sulphuric solution was decom- posed by adding six times its bulk of water ; dark brown oxide was separated ; and the clear fluid evaporated to its former bulk ; then red chamelion of potassa restored the red colour, which appeared exactly like that of the original fluid when they were compared. Two mixtures were prepared — one of sulphuric and manganesic acids, the other of sulphuric acid 58 Mr. T. J. Pearsall on the and colourless protosulphate of manganese ; both were of similar temperature and density ; they produced a clear bright red solution when put together, which, by dilution with water, decomposed, and appeared of an amber tint by the separation of oxide. Protosulphate of manganese may be added to red manganesate of potassa and sulphuric acid without any immediate precipitation. The triple sulphate of ammonia and manganese, when acid, was rendered pink by manganesic acid. The existence of manganesic acid in fluids containing protoxide, at once explains the origin of the rose tints observed in the salts of manganese. These experiments relative to the addition of manganesic acid to the ordinary red solutions, show that the mixture exhi- bits the same colour as a solution of the same depth of tint, either of sulphuric acid and red manganesates, or of the ordi- nary red sulphate ; but the properties so communicated in this case clearly depend upon the known state of manganese, and therefore the evidence is much strengthened in favour of the opinion that the whole of the phenomena of all red solutions of manganese are due to manganesic acid. Having thus found that manganesic acid could do all that the red solutions performed, I endeavoured to obtain the acid itself from solutions formed in the usual mode, by acid and oxide; and as manganesic acid is capable of existing in a state of vapour, I hoped, if it were present, that a small por- tion might be volatilized by distillation. I had previously found that the bleaching alkaline chlorides could hold manga- nesic acid in solution ; very many distillatory experiments were therefore made with the very deeply coloured red sulphate, and in some of them it appeared as though manganesic acid was driven over into the receiver, for a solution of indigo was bleached ; and even the acid itself, by its pink tints and other properties, was evident in the solution of chloride, which re- ceived the extremity of the retort. These results became doubtful, when it was afterwards found that certain proportions of acid protosulphate of manganese when mixed with a solu- tion of bleaching chloride of soda formed manganesic acid. The experiments were therefore repeated with a retort having a long neck, which was bent several times in order to collect Red Solutions of Manganese. 59 any acid fluid during the distillation ; and according as greater precautions were taken, slighter indications of manganesic acid were obtained ; but as the hot fluid which collected in the angles would obviously tend to absorb and interfere with any small portion of volatile matter from the body of the retort, and as the length of transit was also increased, under these circumstances no conclusion can fairly be drawn either way. While the above experiment throws doubt upon the results of vapourizing the crimson fluid, yet it establishes the fact, that manganesic acid is produced when oxides of man- ganese are in solution with substances evolving oxygen, and therefore supports the particular view I have taken*. Experimental comparisons were then made between the red solutions and those containing manganesic acid, with regard to other properties ; but the presence of protoxide of manganese in the red solutions, and the great excess of acid, are circumstances which interfere with and modify the results obtained by the action of some tests, for as yet no process hag been devised for separating protoxide or the proto-salts. Solution of green chamelion of potassa and oxalic acid formed a deep red solution, as also did red manganesate of potassa and binoxalate of potassa. Green manganesate of baryta and binoxalate of potassa produced a rich red solution. These were compared with the crimson fluid from a mixture of binoxalate of potassa and peroxide of manganese. All these solutions became colourless in some hours' time, and in con- centrated solutions deposited white crystals. They are all rendered colourless by heat. Ferro-prussiate of potassa gave in all a peculiar yellow-green precipitate ; hydriodate of potassa a reddish-amber tint in all. Red ferro-prussiate of potassa occa- sioned in the whole a similar red brown turbidness ; by trans- mitted light the edges appeared greenish. With tincture of galls all these solutions became colourless, and deposited light- brown oxide. Proto-muriate of tin rendered them colourless, and precipitated minute white crystals. Sulphuretted hydrogen destroyed colour in all, and rendered them turbid. Caustic * Dr. John described the fact of the volatilization of manganese by distillation some years before manganesic acid was known ; but he supposed it to be a new or different body, and remarks that the experiments must be made upon some pounds of the ore at once,— Annals of Philosophy, ii. 270. 60 Mr. T. J. Pearsall on the potassa, soda, or ammonia, threw down brown oxide in them all. Hydriodate of potassa produces no change in solutions of proto-salts, but it destroys the colour of manganesates, pro- ducing an amber tint of free iodine. The oxalic red fluid is similarly affected, and is identical in colour with the red man- ganesates, if oxalic acid be added to them. Both manganesic acid and the manganesates mixed with oxalic acid give a bright yellow-green precipitate with prussiate of potassa ; a similar precipitate may also be obtained in the ordinary oxalic crimson solutions. By alcohol, the solutions of manganesates and binoxalates afford red crystals. The crimson fluid supposed to hold deut- oxide also throws down red crystals, which appear to have precisely the same properties. Thus, three solutions containing manganesic acid, and a red solution supposed to contain deutoxide, have similar pro- perties. I have not succeeded in forming red solutions by acting with muriatic acid upon oxides of manganese. Diluted muri- atic acid and green manganesate of baryta gave a crimson solution, which, when added to concentrated and neutral muriate of manganese, threw down brown oxide ; but a crim- son transparent fluid resulted when the muriate had excess of acid. Muriatic acid changes green chamelion red, and muriate of manganese may then be mixed with it*. Nitric acid and oxides do not form a red solution, but strong manganesic acid communicates pinkness to the solutions of proto-nitrate of manganese. All these solutions very soon become scarlet and turbid: however, these experiments show that manganesic acid, protoxide of manganese, potassa, or baryta, may exist * H. Rose (Treatise on Chem. Analysis, pp. 91, 92) describes the properties of a dark brown solution of deutoxide of manganese in muriatic acid ; and says that, ' by boiling, the perchloride is rapidly reduced to protochloride.' It is also stated that ' the peroxide of manganese dissolves in the cold acid, and also produces a dark brown solution of deutoxide of manganese.' It may be sufficient for me to observe, that, as these are not red solutions, they need not be considered as opposed to the view which I am supporting ; and even if they should hereafter be proved to contain dissolved deutoxide, then it is obvious that this oxide will give a dark brown, and not a pink or crimson solution. Finally, the perchloride of manganese, when decomposed, forms muriatic and manganesic acids, according to M. Dumas, who discovered this compound. — Edin. Journ, Science, xv., p. 179. Red Solutions of Manganese. 61 together to a certain extent by excess of acid, which condition accompanies all the ordinary red solutions of manganese. Acid solutions of sulphates of potash, soda, magnesia, and zinc, appear of a clear red colour after mixture with the red sulphuric acid, or with manganesate of potassa. The borates of potassa and soda are also reddened by both solutions; and the red sulphate, or the crimson oxalic fluid from oxides, may have their colour increased by the addition of manganesate of potassa. Thus both sets of solutions are similarly compatible with other fluids. When a solution of chloride of lime (bleaching powder) is added to proto-salts of manganese, the protoxide, by the agency of chlorine, receives additional oxygen, and is converted into peroxide. On using the muriate, I observed that, after some days, the supernatant fluid became bright pink ; and, expecting that protoxide of manganese would be absent from this solution, I examined it more particularly. The colour, increasing by time, became pink and violet, like a solution of pure manga- nesic acid, which I found was present, for potassa precipitated lime, and then changed this red fluid to blue and green cha- melion. I have obtained red fluids in this way several times*. The solutions of the bleaching chlorides of potassa and soda have frequently pink tints, supposed to be due to the introduc- tion of manganese in some unknown state into the liquor, while chlorine gas was passing through the apparatus. Prac- tically it was found that the fluids could only be obtained colourless by slowly disengaging the gas ; for whenever the chlorine was rapidly evolved, if the solution was caustic potassa or soda, it always became pink or red. I procured two specimens — the one was colourless, and the other pink ; and I added an aqueous solution of manganesic acid to the colourless fluid, which instantly assumed a similar but much deeper tint than the coloured fluid : then the co- loured fluid had its colour 'greatly increased by manganesic acid ; neither fluid exhibited any other change by such addi- tion. I found that manganesic acid and manganesates were * Mr. Phillips, alluding to the same fact, says, that ' the muriate of manganese should be as nearly saturated as possible, for the chlorine evolved by excess of muriatic acid occasions the acidification of a portion of the manganese,' — Annalj of Phil., N. 8., v., p. 216. J 62 Mr. T. J. Pearsall on the compatible with all the bleaching chlorides of caustic and carbonated alkalies : in some experiments the tints were unchanged after four months. On the supposition that an oxide is the cause of the well- known tints of manganese, it seems difficult or impossible to account for the introduction of any of the oxides into these fluids ; for neither the prot, red, deut, or peroxide, or any of their compounds, are volatile ; and even if one of them be admitted to be present, it could not be retained in these solu- tions, because they are decidedly alkaline. Now^ on the view which I advance, manganesic acid can exist in solutions of carbonates and bi-carbonates, and in these bleaching solutions. Manganesic acid is volatile, as are the perchloride and the fluoride of manganese, which, on decomposing, form manga- nesic acid*. These facts I consider will satisfactorily explain the hitherto almost anomalous appearance of manganese in certain cases of experimental research, and in various processes in the arts f. From all that has been advanced, it would appear that bleaching properties, which have sometimes been attributed to chlorine, in certain cases, belong to all red solutions ; and that these solutions are similar to such as contain manganesic acid — for both solutions are alike in colour and in bleaching power ; both become colourless by the same agents ; both lose the bleaching power by losing the coloured state ; both afford similar indications by reagents ; both, while red, afford a red salt in crystals, which appears to possess the same pro- perties ; both, when they lose colour, afford a crystallized * Quarterly Journal of Science, xxv., p. 486. •f Manganese was observed in a solution of carbonated alkali, into which it had been carried by chlorine, although the gas had been washed with water, and had also passed through an alkaline solution, before the oxide was deposited in the second bottle of Woulfe's apparatus. — Quarterly Journal of Science, vol. xxv., p. 86. Chloride of lime is frequently obtained which dissolves with a pink colour due to manganesic acid, although the chlorine gas had been transmitted through water. Mixtures of chlorides of lime and potassa, prepared for some manufacturing purposes, constantly afford a deep red solution, and possess extraordinary bleach- ing powers. Manganesic acid also colours the solutions in the formation of the salt called chlorate of potassa. Red Solutions of Manganese. 63 colourless proto-salt ; both are compatible with certain other solutions of other substances. From these close and numerous points of comparison, I conclude that the effects of all red solutions of manganese depend upon manganesic acid. The production of manganesic acid in the cases investigated is agreeable to theory ; and if its presence be considered as established, some important consequences follow. The soluble states of manganese are thus resolved into colourless protoxide and manganesic acid. When oxygen is liberated from per- oxide by sulphuric acid, manganesic acid may be alternately produced and destroyed. The composition of any oxide which has been or may be obtained from a red solution will obviously depend upon the quantities of protoxide and manganesic acid ; and this explains the variable proportions which have been obtained with such precipitates. The view I have taken may have many interesting bearings. Thus the red oxide is composed of 28 metal and 10.66 oxy- gen, and the deutoxide of 28 metal and 12 oxygen; and these are assumed to form with acids very feeble indefinite compounds, existing only in the cases referred to, and not volatile. On the contrary, manganesic acid, the cause now assigned of the redness of the solutions, is constituted of 28 metal and 32 oxygen : it is capable of existing in the solid or anhydrous form, or in the state of vapour, and so be trans- ferred from one situation to another. It is soluble in water, in certain alkaline fluids, in some acids, and in solutions of many saline compounds. It is capable of combining with alkalies and earths ; when decomposing, it can impart oxygen to other bodies, and thus produce or modify effects which may have been referred to other causes, when its presence has not been suspected. I have given the evidence as much as possible dependent upon the qualities of the solutions, and purposely so, in order that the view now brought forward may not be interfered with, should the proportions of any of the compounds be subject to correction. Having drawn my conclusions from experiments, I have adverted to the opposing statements of authorities only, to show the opinions entertained upon this subject of acknow Jedged difficulty. 64 ON THE COMPARISON OF BRITISH, FRENCH, AND DUTCH WEIGHTS. BY DR. G. MOLL, Professor in the University of Utrecht. (Communicated by the Author.) TT is well known, that after the conclusion of the labours of A the Commission for the establishment of the metrical sys- tem of weights and measures in France, in 1799, duplicates of the metre and the kilogramme were presented by the National Institute to each of the foreign members of the said Commis- sion, and also to each of the Governments then allied to France, who had sent commissioners, on this occasion, to Paris. These duplicates were authentic copies both of the metre and kilogramme, made and adjusted, it is said, under the immediate inspection of the Commission of Weights and Measures, and carefully and minutely compared with the original standards. After this, they were marked with a par- ticular stamp of the commission, being an ellipse divided into four quadrants, three of which are shaded, and in the fourth, not shaded, the number 10,000,000 is engraved $ thus the form of this stamp is nearly the following. The late Professor Van Swinden was one of the Commis- sioners sent by this country to the general meeting at Paris, and in consequence he became possessed of a set of these authentic copies of the metre and kilogramme, on which he always set the highest value, and which were constantly pre- served with the greatest care. After Mr. Van Swinden's de- mise they came into my possession. Being furnished with one of the well-known balances of Mr. Robinson of Devonshire Street, and with very accurate imperial British troy weights, made by the same artist, I was anxious to compare Mr. Van Swinden's authentic copy of the kilogramme with the British troy weight. Dr. Moll on the Comparison of Weights. 65 The beam of the balance which I employed is about eighteen inches in length ; the knife-edge of the axis is about two inches and a half long ; the knife-edges on which the scale pans are suspended are about one inch. When loaded with a kilogramme in each scale, ^^ of a grain are sufficient to show a derangement in the equilibrium of the beam. In order to ascertain as much as possible how far the weights of Mr. Robinson might be relied on, and within what limits the errors, arising from some inaccuracy in the weights, were likely to be circumscribed, I requested Mr. Bate of the Poultry to make for me a very accurate brass copy of the one pound British imperial troy weight; and it is but justice to say, that this standard greatly excels in point of workmanship, and the care with which it is preserved from external injury, the rather unsightly appearance of the standard kilogramme of Monsieur Fortin's making. This troy pound of Mr. Bate was found, by a mean of very many weighings, to be equal to 5759.935 of Mr. Robinson's grains, making a difference of 0.065 grains, or Tf $&!*'« 15433.42 1.155 8. Idem • • Idem . I 15434.91 2.645 It is said that Dr. Kelly found a copy of a very accurate standard kilogramme, sent over from France to the British Mint, to weigh 15.433 British troy grains, but as I do not pos- sess the Universal Cambist, I take this information at second hand. Dr. Weber of Berlin was furnished with a brass standard of the British imperial troy pound, procured by Professor Schu- macher, with one of Mr. Robinson's balances, and with a pla- tinum kilogramme belonging to the Prussian government. He found 1 Ib. British troy, or 5760 grains =373.2484 grammes *: this makes the kilogramme equal to 15432.08222 grains, leaving a difference with Mr. Van Swinden's kilogramme of 0.183 grains. It is natural and just to suppose that Dr. Weber paid due regard to .the circumstance, that the platina kilogramme, if equal to the weight of the two platina kilo- grammes kept at Paris, one in the Archives Nationales, and * Poggendorff s Annalen der Physik und Chemie, 1830, vol. xviii., No. 4, P. 608. F 2 68 Dr. Moll on the Comparison of the other at the observatory, will be of unequal weight with a correct brass kilogramme weighed in air *. The result of all these experiments is, that we discover differences between weights, which ought to have been equal, which altogether appear intolerable, and there remains an obscurity about the real value of these weights, which it is difficult to account for. Yet, if we are to look to the compa- rative weights of the kilogramme, and the British troy pound, as deduced, not by actual weighing, but by computation, we shall find differences still greater and more bewildering. 1st. In 1769, Tillet, the French academician, determined, by actual weighing, the relation of the British troy pound and French poids de marc f; hence by the known proportion of this poids de marc to the kilogramme, as determined by Lefevre Gineau, we may compute the value of the kilogramme in British troy grains. 2nd. In Dr. Young's Lectures on * Natural Philosophy/ is a calculation of the comparative weight of the kilogramme and British troy, from the known ratio of the metre and British yards, and the experiments of M. Lefevre Gineau and Sir George Shuckburgh on the weight of a cubic decime- ter and a British inch of water at a certain temperature J. 3rd. In the Appendix to the third report of the British commissioners for weights and measures, the result is given of a similar computation drawn from the same source and the repetition of Sir George Shuckburgh' s experiments by Captain Kater§. 4th. Mr. Mathieu of the Paris Observatory, computed from French and English experiments the value of the kilogramme in British troy grains ||. From all these operations the following different relations of the kilogramme to British troy grains was constructed, to which the value of Mr. Van Svvinden's standard kilogramme has been prefixed. We may perhaps, all at once, lay aside the result deduced from Tillet's operations, as probably the * Base du systeme metrique decimal, tome iii., p. 644. r f Tillet, Me"m. de 1' Acad. Roy. des Sciences, 1769, p. 384. J Dr. Young's Lectures on Natural Philosophy, vol. ii., p. 161. § Annals of Philosophy, 1821, New Series, vol. ii., p. 154. || Anuuaire du Bureau des Longitudes, 1829, p. 59. British, French, and Dutch Weights. 69 scales and weights used in his time could hardly possess that accuracy and sensibility which are required at present. No. By whom the Calculations were u made. Kilogramme weighs in British Troy Grains Differences with V. Swinden's Standard. Mr. Van Swinden's Standard. 15432.265 _ 1. jTillet . \ IVan Swinden i 4 *'•' f 15445.716 13.451 grs. 2. f Sir George Shuckbnrgh . 1 \ Dr. Young . . . J 15444.03 11.765 3. J Sir George Shuckburgh 1 (.Mr. Fletcher, Captain Kater J 15444.0 7.735 4. Mr. Mathieu. • » 15438.355 6.090 Differences amounting to such an enormous extent are truly appalling, and some secret cause must exist why all the comparative values of the two weights, as found by calculation, are so widely different from what they are found by actual ponderation. Next, all the kilogrammes, which were actually weighed, differ amongst each other, and also from that standard which was made under the immediate inspection of the contrivers of the metrical system. Of all these, the platina kilogramme used by Dr. Weber is the lightest ; then follows the brass stan- dard of Mr. Van Swinden, and all the rest are considerably heavier. It might be argued that those made in this country were adjusted with no great nicety ; but what are we to say or to think of the differences between those made by Fortin and by Monsieur Gandolfi, balancier de la Monnaie de Paris? Some gross error must undoubtedly lay concealed in some parts of the operations, and strange suspicions as to the source of these errors must arise in the minds of any one who looks into the matter ; perhaps it is not irrational to suppose that errors lurk, where the least light is thrown in. We are in full possession of the facts, on which the deter- mination of the metre rests, but we are far from having such 70 Dr. Moll on the Comparison of full and complete information as to the means by which the kilogramme was determined. The coincidence of the experi- ments on the length of the pendulum made by Captain Kater and Monsieur Biot affords sufficient evidence of the accuracy with which these operations were conducted ; but how the kilogramme was come by, has never been very satisfactorily explained. Indeed, M. Delambre, in the ' Base du Systeme Metrique,' having explained how the metre was determined, says, that the account of the fixation of the unit of weight ought to have followed ; but that 'the multiYarious avocations of Mr. Lefevre Gineau, as professor, as an inspector of studies, and finally as a member of the legislative chamber, did not allow him sufficient leisure to lay the finishing hand to the arrangement of his papers, although the plates were en- graved long ago. In consequence, not the particulars of the experiments, but the account of what was done, as drawn up by Tralles, is given as it was read before the Institute. But this is a report of the experiments, not the description of the experiments themselves ; we have the shadow, not the thing itself, and we are entirely in the dark as to the particulars of so interesting and intricate an operation as the determination of the unit of weight. It must be observed that the operations by which the kilo- gramme was determined were closed in 1799, and that M. Delambre's evidence as to the supineness of M. Lefevre Gineau is given in 1810. Thus, in eleven years M. Lefevre could not spare time for a work so important, and on which his scientific reputation was chiefly to rest : for it must be recollected, that great as the merit of M. Lefevre as a legislator and as an inspector of the University possibly might have been, he has not attached his name to any other scientific operation than the determination of the kilogramme. All this would certainly have been entirely different if the ingenious and lamented Borda, who was the soul of all the operations for determining the metre and kilogramme, had not been untimely snatched away. But, taking the matter as it stands now, it must be confessed, that we know very little of the means by which the unit of weight was determined. But whatever is the degree of uncertainty prevailing about British, French, and Dutch Weights. 71 the real value of the kilogramme, at least the different dupli- cates of this weight should have been equal amongst each other, which, however, is far from being the case. 1 am sorry to add, that some such variation is, to a certain extent, pre- vailing as to the British troy pound. I have noticed already, that there is some slight difference between Mr. Bate's troy pound and Mr. Robinson's 5760 grains, but there are instances of much greater differences. In 1818 the British consul at Rotterdam applied to the general masters of the mint at Utrecht for a standard copy of that weight, which, at that time, was used in the Mint of this country. In consequence, a standard copy of the Dutch troy pound was prepared and forwarded to the British consul, and he was requested to procure in return a standard of the British troy pound. Agreeably to this, two copies of a brass standard British troy pound were adjusted at the Mint in London, and sent to this country, together with a certificate from a Mr. Field of the London Mint. I have examined both these copies of the British troy pound, and one is actually in my possession, whilst the other is kept at the Mint office in this city. Upon each of these brass troy pounds the following inscription is engraved, which stamps them, as it were, with a character of officiality : BRITISH TROY POUND = 5760 GRAINS. FROM HIS MAJESTY'S MINT. Notwithstanding this certificate of authenticity, and a paper belonging to them, in which a Mr. Field, an officer, as it would appear, of the Mint, asserts that they were carefully adjusted, both these weights are unequal to each other, and to the 5760 of Mr. Robinson's grains. That which is at present kept in the Mint Office of Utrecht weighs 5758.57 grs. The second, now in my possession 4 , . 5758.40 „ Whilst Mr. Bate's imperial troy pound holds , . : , r fei. 5759-935 » It is exceedingly vexing to see weights adjusted in the Mint of England, and on which expense has not been spared*, differing more than •£$ of a grain from each other. Further- more, the difference of these weights, Mr. Robinson's grains * The sum of 5/, 5s, was charged for making and adjusting these weights. 72 Dr. Moll on the Comparison of and Mr. Bate's pound, is so great, that we cannot help think- ing but that there must exist some notable difference between the Mint standard of troy weight and that according to which both Mr. Robinson and Mr. Bate made their copies. By an act of the 5th George IV., the standard of 1758, in the custody of the Clerk of the House of Commons, is de- clared standard of the British troy weight. This standard was made or adjusted in 1758 by Mr. Harris, then Assay-master of the Mint. We cannot, therefore, but admit that, since 1758, an enormous and unaccountable change took place be- tween the troy weight as used in the Mint of England and that copy which remained unaltered in the custody of one of the principal officers of the House of Commons. Although the weights formerly in use in this country have been abolished and replaced by the French kilogramme, it may not perhaps be altogether superfluous to compare these old weights with the British troy and avoirdupois, as esta- blished by the act of 17th June, 1824, 5th George IV. Formerly there were three different sorts of Dutch weights in use in Holland. 1. The Dutch troy weight, differing essentially from the British troy. It was used in the concerns of the Mint, in the weighing of gold and silver, and also for medical, pharma- ceutical, and philosophical purposes. In the province of Friesland it was the general weight for commercial transac- tions, and no other weight was employed there. 2. The Amsterdam commercial weight, generally used throughout the country for all commercial concerns on a large scale ; it was originally derived from troy weight. 3. In shops, and for the retail trade, a light weight was almost generally used, except in Amsterdam. It was also employed, in some cases, in the iron trade. It is originally the Antwerp weight. The general opinion is that troy weight derives its name from the city of Troyes in Champagne, in which place it appears that very heavy weight was used in old times. It would seem, however, that there is no document in existence at present, in the records of that town, which is calculated to throw any additional light on the history of the introduction of this British, French, and Dutch Weights. 73 weight, which, with different modifications, has been adopted both in Holland and England. In the fifteenth century, troy weight was used in Amster- dam ; and in 1520, the Emperor Charles V., then sovereign of the Low Countries, ordered that the mint-masters in the several provinces should adjust their weights to the standard of troy weight kept in the offices of the several courts of ac- counts (cours des comptes} in the different provinces. The old standard of this weight, even now existing in the Hague, has been adjusted in 1554 to the standard of the court of accounts of Brabant at Brussels. The same regulations as to the use of troy weight have been reinforced by the statute of the Earl of Leycester in 1586, and by that of the States-General of 1606. However, the troy weight in use in the Seven United Provinces for upwards of a century down to the time of its being abolished in 1819, was somewhat different from the old standards ; but these matters, being of a local nature, do not require to be stated here in all their particulars. Mr. Van Swinden, before he set out for Paris in 1798, to attend the meetings of the great commission of weights and measures, procured a copy of the Dutch troy weight, as it had been used for more than a century, and had it adjusted with great care. This duplicate Dutch troy weight he took to Paris, and by its means, he, M. Aeneae, the second commissioner, and M. Lefevre Gineau investigated and determined, with all the accuracy which they could, the relative proportion between the Dutch troy weight and the kilogramme. This standard, religiously preserved, came also into my possession, and I have several times weighed it against Mr. Robinson's British troy grains, with all the attention which I could master. Ac- cordingly the weight of One brass pound of Dutch troy weight is 7594.975 grains of Mr. Robinson. = 15 oz. 16 dwt. 10.975 grs. — 15 oz. 6 drachms, 1 scruple, 14.975 grs. And one pound Dutch troy = 0.7583961764193 Ib. British troy. One ounce Dutch troy . . . .rr 474.6856 grs. British troy. One grain Dutch troy = 0.989 gr. British troy. One grain British troy. . . .r= 1.0112 Dutch troy. And finally, assuming the kilogramme to be equal to 15432.265 of Mr. Robinson's grains, we have one pound Dutch troy weight equal to 492. 14907857 grammes. 74 Dr. Moll on the Comparison of The Dutch troy weight, as used for weighing bullion and the precious metals in general, has sixteen ounces, but for medical and pharmaceutical purposes, there are twelve ounces in the pound. But the ounces are the same in both cases, and con- tain 480 grains. For mint purposes and the weighing of bullion, the division of the Dutch troy was as follows : 1 lb. Dutch troy=2 merks, 1 merk=8 ounces 1 ounce=20 sterlings (English):=480 grains. 1 sterling=z32 aas. Thus 1 lb. Dutch troy=10240 aas±±7680 Dutch troy grains. =7594.975 British troy grains. For medical and pharmaceutic use, the division of the Dutch troy ounce was as follows : One Dutch troy ounce=8 drachms =480 grains. =1 drachm = 3 scruples=r60 grains. 1 scruple;rz20 grains. As the British avoirdupois contains 7000 grains, British troy, it is a matter of computation to deduce from thence the relation of the Dutch weight to English avoirdupois. 1 lb. avoirdupoisrriO . 921 66202 lb. 1 =14 oz. 14 sterling, 29.8181 aas. ?Dutch troy weight, =7078.3643 grains. J and inversely, 1 lb. Dutch troy =1 .0849964 lb. avoirdupois. rrl lb. 1 oz. 5 .75908 drachms avoirdupois. In the golden old times of trade, the magistrates of Amster- dam were anxious that the commercial weight of that city should be heavier than that used in other trading -places. Therefore it was established by law, that the Amsterdam com- mercial pound should be 40 aas in the pound heavier than troy weight. In consequence of this regulation, we have the following relations between British and Hollands commercial weights. 1 lb. avoirdupois— 0 . 9180754 lb. Amsterdam weight. =14 oz, 1 .37841 lood Amsterdam weight *. 1 Ib.Amsterdamrrl. 0892347 lb avoirdupois. * The Amsterdam pound is divided into thirty-two parts called looden^ for which 1 know of no English corresponding word. British, French, and Dutch Weights. 75 An English hundredweight, or 1121b, avoirdupois=102.8241b, Amsterdam weight. How far the use of heavier weight than our neighbours may be beneficial in a commercial point of view, and whether such attempts may lead to any practical result, is not for me to investigate. I. ON A REMARKABLE CASE OF CORYZA PHLEGMATICA. II. ON THE DIRECT FORMATION OF OXIDE OF IODINE AND IODOUS ACID. III. ON NITROGEN IN NATURAL WATERS. By the CAVALIERE LUIGI SEMENTINI, of Naples, M.R.I. &c. In a Letter addressed to the Secretary of the Royal Institution. I. /^ORYZA PHLEGMATICA. — The following account of an uncommon disease, which has recently come under my observation and cure, may not be unacceptable. A similar affection has been called by Sauvages and Borsieri, Coryza Phlegmatica or Phlegmatoragia. The patient, who was about fifty years old, abounding in humours, and of a sanguine temperament, after a strong fit of sneezing, was suddenly affected with a constant running from the right nostril of a clear liquid, in large drops, to the number of twenty-five in a minute, and of twelve at the least ; but the diminished number occurred only during the hour after dinner. The discharge increased to the larger number of twenty-five drops per minute in the evening, and continued without inter- ruption during the whole course of the night. Hence the patient was obliged to take his rest in an uneasy position, with his head inclined forward, without which precaution he would have been suffocated. In walking, on the contrary, he went with his head erect, in order that the liquid might fall into the fauces, from whence he discharged it by large mouthfuls, thus avoiding the disgust of having his face and clothes continually soiled. The fluid in 'question had a strong saline taste, and the patient was obliged to muffle up his nose during meals, in 76 Sementini on Coryza Phlegmatica. order that it might not mix with his food. Nevertheless, he was not afflicted with head-ache, nor with any uneasy sensa- tion in the fore-part of the head, nor indeed with any of the ordinary phenomena accompanying such diseases. He only lost a little flesh, and in other respects enjoyed perfect health. This disease, which, in my time at least, has not been known to occur in Naples, is described by the celebrated Morgagni in his fourteenth Medico-Anatomical Letter, where he treats of the diseases of the head. But the case he describes of a Vene- tian lady, who was affected with it, and cured by him, differs from that which came under my observation, in that the quan- tity of the fluid discharged was not above one half, and that it- continued for near a year, while in my patient it continued only four months ; and because the health of the lady was so sensibly affected by it, as to endanger her life. The disease was for a long time treated by me in the accus- tomed derivative method of foot-baths, blisters, sudorifics, purgatives, &c., but in vain. Afterwards, remembering that the afflicted person was subject to the gout, though in an anomalous and irregular form, I was of opinion that a portion of the gouty humour might have affected the olfactory nerves ; and the result of my experience being that no means were more effective than James's antimonial powders to reduce this disease to a state of regularity, and therefore probably to remove this humour from the unaccustomed seat it occupied, I subjected the patient to a course of that medicine. At the end of four days, his head, which had always been free from pain, became slightly affected ; and at length, after profuse perspirations, the disease, which had come suddenly, ceased in a manner quite as sudden. The fluid discharged, although transparent and limpid when it first issued from the nostril, soon became turbid, and acquired a light yellow colour, depositing a flocculent animal substance. In its composition, beside the muriate and phosphate of soda, I found a considerable quantity of urate of soda, especially in the flocculent deposit : there was scarcely any free soda. Sementini on Oxide of Iodine* 77 II. IODINE AND OXYGKN. — I presume that you are acquainted with my experiments on the combinations of iodine constituting the oxide of iodine and the iodous acid*. This second sub- stance was obtained by triturating the chlorate of potassa with iodine, and heating the mixture in a distillatory apparatus. ButWoehler having objected that this substance was a chloride of iodine, and not a distinct acid, I was obliged to vary the experiments, the results of which I am anxious to communi- cate to the members of the Royal Institution without delay. In replying to Woehler, I undertake to prove that, on all occasions when iodine is brought in contact with pure oxygen gas, or even with common atmospheric air, at a high tempera* ture, combination takes place, forming first oxide of iodine, and afterwards iodous acid, without the intervention of any other substance. I request your attention to the circumstance of an elevated temperature, because, in the French translation of Berzelius's ' Chemistry,' published at Paris, a low tempera- ture is mentioned, which would prevent the success of the experiment to which I have the honour to refer you below. The tube A B of cast brass should be of the diameter of a barometer tube, and ought to terminate at the end B in a capil- lary aperture. It should be fixed to the supports E C, D F. At the extremity A, a bladder G with a stop-cock should be fixed on, which is to be filled with oxygen gas, or even with mere air. The oblong spirit-lamp H H is to be so placed that the flame of its burners may act upon the whole length of the brass tube A B. The extremity B of the tube is to enter the tubular opening of the empty retort K, into which it is to be fixed by luting. Under the bulb of the retort is to be placed the large spirit-lamp L. * Quarterly Journal of Science, vol. xvii, 381, and vol. xxiii, 477. 78 Sementini on Oxide of Iodine. The apparatus thus disposed, the burners of the lamp H H being lighted, and that of the lamp L placed under the retort ; when the tube and the retort are very hot, the bladder at the end of the tube is to be pressed by an assistant, forcing the gas to issue from the capillary end of the tube, the experi- menter, at the same time, introducing a spoonfull of iodine into the neck of the retort, so that the bowl of the spoon may come immediately under the capillary opening of the tube A B. In this operation the iodine is soon raised into vapour, which coming immediately into contact with the heated oxygen gas, combines with it, and assumes the form of an amber-coloured vapour, which condensing in the neck of the retort, becomes a dense oily fluid, which is the oxide of iodine, first discovered by me. By continuing the jet of oxygen gas, I have upon two occa- sions obtained iodous acid, but it is incumbent on me freely to confess, that in following up the experiments lately I have not had the same result, without being able to account for the cause of such irregularity. Yet, nevertheless, by these or by any other means, when iodine is made to combine with oxygen at a high temperature, the oxide of iodine is constantly obtained. The following is a new experiment by which it may be obtained in consider- able quantities without complicated apparatus, and by the employment of such simple means that no doubt or discussion can arise as to its nature. The deutoxide of barium is to be triturated for some time with iodine, in such proportions that the iodine is in excess, and that the mixture acquires a blackish colour. This pow- der is afterwards to be introduced into a small retort with a long neck, and the heat of a large spirit-lamp applied. The violet-coloured vapour which first appears is soon succeeded by the yellow vapours of the oxide of iodine, which substance collects in the neck of the retort, and ultimately drops from it. The same result is obtained with the protoxide of barium, but the effects are less sensible and the product not so abundant; in operating with the protoxide as well as the deutoxide, oxygen gas is always developed. When the substances employed are free from water, the fol- lowing are the properties by which the oxide of iodine is dis- tinguished ; — Sementini on Oxide of Iodine. 79 1. It has a yellow amber colour. 2. It is soluble in water and in alcohol, forming coloured solutions. 3. It is thick like oil, and it is frequently necessary to heat the neck of the retort in order to collect it, after which it re- mains more fluid. The excess of iodine frequently causes the violet-coloured vapour to pass over with the oxide of iodine ; which, however, does not alter the result of the operation, as the two substances do not mix. If the iodine and the oxide of barium are not perfectly dry, the oxide of iodine is much more fluid. It changes the colour of blue litmus paper to an eme- rald green. Oxygen is so slightly united to iodine, that the simple con- tact of a combustible body at any temperature suffices to dis- unite them, and the iodine is separated with all its properties. Whether the oxide be concentrated or weak, its decomposition is effected by mere contact, even with a piece of white card, which soon becomes covered with a black stratum of iodine. When the oxide is in its state of greatest density, it ignites phosphorus and potassium by simple contact. By such evident proofs, therefore, the formation of the oxide of iodine is demonstrated ; that of iodous acid becomes very simple and clear, as I shall have the honour of communicating in a future paper in which I purpose to treat of the iodites. The few facts above stated have not yet been published, with the exception of that which relates to the action of air or oxygen gas with iodine at a high temperature, and I commu- nicate them to the Royal Institution as a mark of my respect, in order that they may be published in the Journal, should they be thought worthy of it. III. NITROGEN IN THE WATERS OF CASTELLAMARE — A com- mission, of which I am a member, has undertaken the ana- lysis of the mineral waters of Castellamare, but owing to my indisposition its labours are not yet finished. Reserving to myself the pleasure of communicating to you the results when completed, I will merely now state that their 80 Mr. Knight on the direction of composition is very similar to that of the waters of Spa. Every season the concourse of English visiters to those waters is con- siderable : it may not, therefore, be uninteresting to medi- cal men to learn, that these waters contain azote in consider- able quantities: — a fact not new in chemistry, but yet not common, and of great importance. ON THE DIRECTION OF THE RADICLE AND GERMEN DURING THE VEGETATION OF SEEDS. By THOMAS ANDREW KNIGHT, Esq., F.R.S., President of the Horticultural Society, &c. TN the ' Quarterly Journal of Science ' of the last year, (of which publication I regard the 'Journal of the Royal Insti- tution' to be, in some degree, a continuation,) a communication, made by M. Poiteau to the ' Societe d'Horticulture ' of Paris, is noticed ; in which that writer considers himself to have totally refuted and annihilated my hypothesis respecting the descent of the radicle and ascent of the germ of germinating seeds, which was published in the ' Philosophical Transactions ' of 1806. M. Poiteau proceeds to slay the slain; for after having, as he supposes, proved that my inferences are not physiologically correct, he goes on to say that they are not at all physiological, and that ' II convient done que les bota- nistes raient 1'expe'rience de MM. Knight et Dutrochet du catalogue des experiences de physiologic ve'getale,' having pre- viously determined that ' il n'y a rien de physiologique dans 1'expe'rience de M. Knight.' I had previously seen several attempts to refute my hypo- thesis 5 but, in all these, it was either misunderstood or widely misrepresented. I must give M. Poiteau, however, the credit of having fully understood and fairly represented my hypo- thesis ; and the only grounds upon which I can object to his conclusions are that, as far as they are connected with vege- table physiology, all his premises and all his inferences are false ; and that if all his premises had been perfectly true, all his inferences would have been totally erroneous. M. Poiteau attached pieces of metal, of the form of the the Radicle and Germen of Seeds. 81 seeds of gourds, to the circumference of wheels, similar to those upon which I bound germinating seeds, each piece of metal being perforated near its more pointed and smaller end, and fixed to the wheel by a pivot, round which it was left at liberty to revolve. When these pieces of metal were sub- jected to the operation of centrifugal force, their heavier ends necessarily receded from the axis of rotation, and the lighter ends were necessarily made to point towards it. M. Poiteau conceives that nothing more occurred in my experiments and those of M. Dutrochet, who repeated the same experiments with very superior machinery, and with the same results ; and that the sole cause why the germs approached the axis of rota- tion was, that their specific gravity is not greater than one-third that of the radicles. I was not so fortunate as to be able to comprehend this ; and though I gave M. Poiteau full credit for accuracy respecting the different degrees of specific gravity of the substance of the radicles and germs, I thought the fact a very extraordinary one. I therefore planted a couple of dozen seeds of the plant (phaseolus vulgaris) which was the subject x)f M. Poiteau's experiment, and I then discovered, to my astonishment, I confess, that the radicles, instead of pos- sessing a degree of specific gravity three times greater than that of the germs, were really the lighter body of the two, the germs having all sunk to the bottom of the same vessel of water in which all the radicles rose to the surface. I. repeated this experiment several times, and always with the same result, having detached both the radicles and germs from their cotyledons as soon as the germs became visible above the sur- face of the ground. The seeds in my experiments were bound firmly to the cir- cumference of the wheels, instead of being, as M. Poiteau's pieces of metal were, left at liberty to revolve upon pivots; and the direction taken by the radicles and germs of seeds is totally independent of each other. The germ is never made to deviate, in any degree, from its perpendicular line of growth upwards by any obstacle which the radicle meets with in its descent; nor is the direction of the radicle ever influenced, in any degree, by that taken by the germ. If the seed of a peach, or pear, or other tree which nature intended to support VOL. II. Aua. 1831. G 82 Mr. Knight on the Radicle and Germen of Seeds. itself be planted, its germ -will be seen to incline towards any point from which it receives most light; whilst the germ spring- ing from the seed of ivy, or other plant which nature intended to rely upon the support of some other body, will recede from light and seek the shade ; but the radicles of all will be found to proceed alike perpendicularly downwards; and, therefore, if the specific gravity of the radicles had exceeded that of the germs to the extent conceived by M. Poiteau, that circum- stance, as the seeds in my experiments were bound firmly to the circumference of the wheels, could not, in any degree whatever, have caused the germs in their growth to have approached their axis of rotation. M. Poiteau must, there- fore, allow me to consider his production as a succession of blunders from beginning to end. I wished M. Dutrochet to refute M. Poiteau's hypothesis; but he seemed to think that M. Poiteau's errors would be obvious to every reader before he could publish his exposition of them; and I should have agreed in opinion with M. Du- trochet if M. Poiteau's communication, instead of his assump- tion, had been published in the 'Quarterly Journal of Science;' but, as it was not, and as the knowledge of the influence of gravitation upon the moving fluids of plants, and conse- quently upon their growth, forms, and produce, is important to the scientific gardener ; and as I had the honour to receive from the Royal Society Sir Godfrey Copley's medal for the memoir which gave a statement of my facts and hypothesis, I have thought it proper to shew that M. Poiteau's conclusions are not quite so accurate and unquestionable as he appears to have imagined them to be. Downton, July 8, 1831. 63 ON DISINFECTION AND THE PRACTICE OF QUARAN- TINE ; WItH SOME REMARKS AND COMMUNICATIONS RELATIVE TO CONTAGIOUS DISEASE, AND ESPECI- ALLY THE CHOLERA. BY ANDREW URE, M.D., F.R.S., &e. &c. T^HE remarkable power of chlorine, and of its officinal com- pounds, chloride of lime arid soda, in decomposing and destroying the fetid effluvia of animal and vegetable bodies in a state of putrefaction, has been so long known, has been verified in so many instances, and is susceptible of such direct demonstration, as to be beyond the cavils of medical pyrrhon- isni in its most wanton mood. That these effluvia are capable of making morbific impressions on tne living body, is also placed beyond any reasonable doubt, not only by the sickness they instantly occasion, but by the many recorded cases of fevers of a putrid or low typhoid type, brought on by incau- tious exposure to masses of animal matter far advanced in putrefaction. The power of such matter to produce fevers by inoculation, has been often fatally exemplified in the dissect- ing schools ; and the power of a lotion of chloride of lime or soda to counteract danger from such inoculation, is now equally Well ascertained. In a letter just received from my son, at present House-Surgeon of the Glasgow Royal Infir- mary, he says, ' Having performed several post mortem dis- sections of persons who have died from malignant fevers, dysentery with extensive ulceration of the mucous membrane of the large intestines, peritonitis with purulent effusion into the abdomen, hectic from suppuration, gangrene, &c., I have never suffered the slightest inconvenience. Yet these are the cases in which that peculiar animal poison is especially gene- rated which has occasionally proved fatal to the demonstrator of disease. I attribute the immunity I have enjoyed, in a great measure, to my washing my hands immediately after each inspection with the chloro-sodaic liquor of Labarraque ; this I prefer to the solution of chloride of lime, as it is not so apt to injure the skin. ( A young gentleman, who acted as my colleague during G 2 84 Dr. lire on Disinfection. part of last winter, but who did not adopt the above precaution, having imbibed through a minute breach of surface on his little finger a portion of this virus, was in a few hours there- after attacked with acute inflammation of the absorbents of the arm, accompanied with high symptomatic fever, which con- fined him to his bed for many weeks, and required the most powerful antiphlogistic measures to subdue the inflammatory symptoms. I could cite instances of my predecessors having suffered from the same cause, but I deem it unnecessary, as the fact is indisputable.' A mournful example of the danger of putrefactive effluvia occurred a considerable time ago in the north of Scotland. Two young medical men, desirous of examining a body which had been interred without dissection, in consequence of the prejudices of the relations of the deceased, went in a very dark night to exhume it, but having mistaken the grave, laid open a coffin replete with such noisome corruption, that the gentle- men instantly sickened with the fetor, were hardly able to go home, where they forthwith took to bed with symptoms of malignant fever, and died. MM. Orfila, Leseure, Gerdy, and Hennelle, were employed, about seven years ago, in Paris, to examine the body of an individual who was supposed to have been poisoned, and who had been dead and buried for nearly a month. Had they rashly proceeded to the inspection, they would most probably have fallen victims to their imprudence ; but the smell was intolerable, and the body could hardly be approached; they had, therefore, recourse to chloride of lime, sprinkling a solution of it over the putrid corpse, which pro- duced, after a few aspersions, such a wonderful effect, that the nauseous effluvia were instantly quenched, and the dissection was performed with comparative comfort. Chloride of lime has been repeatedly used since with equal efficacy in similar cases ; it has become a familiar anti putrescent agent in the anatomical theatre, and has been ap plied to destroy the stench of bilge-water and common sewers with unfailing efficacy. Its operation on fish so much tainted as to be hardly fit for the table I have myself repeatedly tried, and I have found that a dish of such fish cleaned and opened up, by immersion in a dilute solution of the chloride for a few Dr. Ure on Disinfection. 85 minutes, loses the dark colour at the bone and all offensive scent ; and after being washed in water, when boiled it pos- sesses the curdy firmness, sea-air flavour, and taste of newly caught fish. An ounce of good chloride of lime is sufficient to sweeten a very large dish. The phenomena of putrefactive fermentation seem to show that the fetor resides in certain hydrogenated compounds, con- taining carbon, sulphur, phosphorus, azote, &c. ; for gaseous matter of this kind is eventually disengaged in the larger cavi- ties of the trunk, as well as in the cellular tissue, causing a general intumescence. There is every probability, likewise, that the diffusible fomes of contagious disease resides in some analogous compounds, but of so subtle a nature as hitherto to have baffled every effort of chemistry to collect and analyze. The same thing may be said of the miasmata of marshes. The infectious virus of plague, small-pox, and putrid bodies, resembles in some measure the poisonous secretion of venom- ous reptiles, and is of a more durable composition and less volatile (so to speak) than the effluvia of typhus, scarlatina, and measles. We can therefore easily understand why an agency capable of decomposing the former morbific powers, may be feeble to grapple with the latter, embodied as they are in a too palpable humour or a solid crust. Guy ton Morveau appears to have been the first man of science who directed the resources of pneumatic chemistry in a regular manner to the purpose of disinfection. The Cathe- dral of Dijon had been for several years infested with a febrile fomes or miasma, which occasioned fever in many of its pious visitants, and it had become in consequence nearly deserted as a place of worship. Being then (1774) Professor of Che- mistry in the Academy of Dijon, M. Guyton was naturally induced to exercise his science in expurgating the air of the church. He accordingly filled the whole capacity of the building with muriatic acid gas, disengaged from a mixture of salt and sulphuric acid distributed in a number of stone-ware dishes. The doors and windows were kept close for two or three days, to prevent the dissipation of the acid fumes. At the end of this period a free ventilation was given by opening the doors and windows, after which the church was found 86 Dr. Ure on Disinfection. to be Deprived of its unpleasant smell and unwholesome effluvia. In 1796, Dr. Carmichael Smith applied the fumes of nitric acid, disengaged from nitre by sulphuric acid, to the disin- fection of a ship's hospital, for which he received a consider- able parliamentary reward. Since that time the progress of chemical research has made us more fully acquainted with the intense affinity which exists between chlorine and all hydrogenated compounds, and with the resulting anti-putrescent quality of chloride of lime. Hence chlorine has naturally come to be regarded as the most energetic antiloimic agent. In this respect, likewise, the merit of its introduction belongs to M. Guyton, who recommended medical men, nurses, and other attendants on contagious dis- ease, to carry about with them phials containing manganese and muriatic acid, and to open the glass stopper from time to time in situations replete with infectious effluvia, in order that the chlorine exhalations might decompose them, and pre- serve a healthy atmosphere for respiration. In the sequel of the present paper, facts will be adduced apparently proving the efficacy of this antidote to the contagion of cholera. As gaseous chlorine in the state in which it is evolved from muriatic acid and manganese, has been thought to be too con- centrated for diffusing in apartments occupied by the sick, recourse has been had in a great variety of cases to the exha- lations that spontaneously rise from chloride of lime exposed in an extensive surface, either in its pulverulent form or dis- solved in water. It is true, indeed, that under both of these forms the chloride exhales its peculiar odour, but it gives out no appreciable or operative portion of gas, and instead of losing, it gains weight. I have suspended a piece of moist litmus paper within three inches of good chloride of lime, in a stoppered phial for upwards of an hour, without its being blanched ; nay, the paper retained much of its colour at the end of twenty-four hours. As the paper would have become white in a few minutes by the admission to the phial of one- tenth of a cubic inch of chlorine gas, it is obvious that even that minute volume was not disengaged from the chloride, which amounted to nearly 500 grains. But by the agency of Dr. Ure on Disinfection. 87 muriatic acid, that quantity of the said chloride would have evolved about 145 grains, or 190 cubic inches of pure gas. I may remark, that few samples of the bleaching-powder found in the market are impregnated like the above with fully 29 per cent, of chlorine, and the stuff retailed in many shops under that name seldom contains more than 16 per cent. As for the liquid chloride of lime, the two-shilling bottles occasionally possess no more virtue than would be found in two-pennyworth of Messrs. Tennant's dry bleaching salt. Nothing, therefore, can exceed in absurdity the fashionable nostrum for disinfecting apartments charged with contagious fomes, by placing in them one or more saucers filled with chloride of lime. To place this dangerous fallacy in the plainest light, I need merely state that moist litmus paper may be hung for a day a very few inches above such a saucer without perceptibly losing colour; whereas the affusion of a few drops of muriatic acid on the same chloride, even after the above period, will instantly blanch the suspended paper. It has been supposed that the carbonic acid present in the atmosphere displaces the chlorine from the lime ; but how slowly and insignificantly the preceding experiment may show. The following facts have been long before the medico-chemical world. 6 After passing a current of this gas (carbonic acid) for a whole day through the chloride diffused in tepid water, I found the liquid still to possess the power of discharging the colour very readily from litmus paper *.' Chloride of lime laid out in the air passes rapidly into a deliquescent paste, consisting of muriate of lime, and lime with an obscure displacement of oxygen. If the chloride be sur- charged with chlorine, it speedily gives off the excess and becomes commercial chloride. The best manufacturers, aware of this circumstance, never push the impregnation beyond a certain pitch; in which state the chloride does not sponta- neously emit in the air one-thousandth part of its condensed chlorine. To pretend, therefore, to suffocate the hydra of con- tagion by subjecting it to the simple smell of chloride of lime ** On the Manufacture and Composition of Chloride of Lime, by Dr. Ure, Quarterly Journal of Science and the Arts, for July, 1322. 88 Dr. U re on Disinfection. in a saucer, is just such a mockery as it would be to appease the famished stomach by the smell of a cook-shop. The subtle effluvia of a pestilence must be combated by more energetic means ; they must be environed with an atmosphere of chlo- rine adequate to effect their destruction. Every thing short of this consummation is paltering with the safety, not of a few individuals, but possibly of a nation. But I shall be asked, whether chlorine gas can be diffused through the air of a chamber without injuring the lungs of living beings, as well as the furniture and goods ? I answer yes, when it is distributed on philosophical principles. But I might ask the medical practitioner, in return, whether the corrosive sulphuric and nitric acids may be administered internally? Yes, he would be ready to reply, when suffi- ciently diluted ; and the same answer will serve for chlorine. I have been a frequent inmate of manufactories of chloride of lime on the greatest scale, and I have occasionally found the atmosphere, in certain departments of the works, to be impregnated, in a sensible degree, with chlorine gas. Moist litmus paper would have speedily lost its colour in such an atmosphere, although dyed woollen and calico stuffs, in the dry state, suffered no perceptible change. The workmen who habitually respired this chlorified air experienced no evil effects on their health, nor, indeed, any inconvenience at all, unless an accident befel some joint of their apparatus. These facts prove the safety of immersion in chlorine largely di- luted with air, yet still strong enough to blanch moist litmus paper; which may be regarded as a satisfactory criterion of its activity when directed against contagion. In applying chlorine gas to apartments, we should always bear in mind, that it is one of the heaviest of elastic fluids, and therefore it tends to occupy the lower region in preference to the upper. If, in the little cave near Naples, called the Grotto del Canit the carbonic acid adheres closely to the floor, so that, by rising hardly above the knee, a man con- tinues to breathe in perfect ease, unconscious of the presence of his invisible foe, while the dog at his foot is instantly suffo- cated, we may judge how much more closely a stratum of chlorine should adhere — a gas nearly double in density to Dr. lire on Disinfection. 89 carbonic acid ; for air, carbonic acid, and chlorine are in spe- cific gravity respectively as 2, 3, and 5. We need not be told that chlorine, like other gaseous matter, has the faculty of diffusing itself slowly upwards through atmospheric air; but this is only when it has nothing else to do, for when it encoun- ters substances on which it can exercise its pre-eminent affi- nities, it will combine with them, probably to their destruction, and certainly to its own, as an influential gas. In proof of this position, I have many experiments to adduce, one of which was exhibited before the Marquess of Lansdowne, Sir Henry Halford, and the whole Board of Health in the Royal College of Physicians, on Friday evening, the 24th of June. Having had the honour, two evenings before, to submit to that Board a plan for disinfecting the cargoes of ships, by dis- tributing dilute chlorine through their holds by the apparatus, figured No. 1, illustrative of this paper, doubts were strongly, and very naturally, expressed by many members of the Board, as to the penetrability of dense bales of hemp, wool, and cotton by the chlorine gas. I was asked, whether I could satisfy them on this head by an experiment ; and if so, how soon. I undertook to make the experiment in two days ; but an anxiety being shown to have it tried next day, I promised to do my endeavour, with such apparatus as I could command. Accordingly, on the 23rd of June, at four o'clock P.M., minia- ture bales of hemp, wool, and cotton were made up as dense as possible, the latter two being moreover inclosed in thick canvas bags. They were all put into a tali glass cylinder, open at top, the hemp being placed at the bottom. Chlorine was now introduced through a glass tube, which descended beneath the middle of the jar. In the centre of each parcel, a bit of moist litmus paper was placed before it was bound up. Next evening at nine o'clock, the Board having met again, the little bales were opened, and the papers in their centres were rendered snow-white, clearly proving the penetration. The external fibres of the hemp parcel were so corroded by the chlorine as to be easily torn asunder ; while the fibres of the canvas bags, placed above, were not in the slightest degree affected, nor the wool and cotton within them. I have since 90 Dr. Ure on Disinfection found that pure chlorine is pretty quickly absorbed by un- bleached hemp, with the extinction of the peculiar pungent smell of the gas ; but that dilute chlorine blown through among its fibres will blanch moist litmus-paper enclosed in a compact bale, without impairing the tenacity of the hemp in the slightest degree. If merely so much chlorine be intro- duced without agitation, through a tube, into a vessel, as to fill its lower half where a hemp package lies, the gas will not spontaneously mount to the upper half, but will concentrate and expend its energies on the organic fibres below. In like manner, if chlorine be made to exhale from capsules placed on the floor of a still apartment, containing beds and other fur- niture, the gas will be arrested in its diffusive ascent, and will never reach in adequate force the upper walls or ceiling to which the hot effluvia of contagious pyrexiae (as typhus, scar- latina, small-pox, &c.) naturally rise. Should the walls of the apartment have been recently washed with milk of lime, the gas will be condensed on them ; but, if washed with whitening, no absorption will ensue ; for chlorine does not displace car- bonic acid from lime, nor does it combine with the calcareous carbonate. We are thus clearly led to the conclusion that chlorine-gas, when used as a disinfector, should be considerably diluted with air before it is distributed into apartments, in such a degree and manner as neither to injure furniture nor merchandize, nor materially to annoy respiration. We must throw out of view those constitutions indeed which are so delicate or fas- tidious as to be intolerant of even the smell of chlorine. The said aerial mixture should be introduced into the middle or upper regions, in preference to the lower, and its diffusion should be promoted by propulsion. Moist litmus paper, sus- pended in various parts of the chamber, will serve to show when the chlorine has done its duty. Figures 1 and 2 (pp. 91 and 93) exhibit two forms of apparatus for disengaging chlorine in regulated quantities, for mixing it with air in any proportion, for blowing it into any infected space, and for ascertaining the degree of its dilution at any stage of the operation. Figure 1 has been constructed in the Dock- Dr. Ure on Disinfection. . 1. yard at Woolwich, by order of Sir T. Byam Martin, Comp- troller of the Navy, from a drawing furnished by me, the copy of that laid before the Board of Health on the 22nd of June. The object of this construction is to show how the cargo of a ship may be imbued with dilute chlorine, without injuring its quality or disturbing its position. Such an easy, quick, and safe immersion in this expurgative gaseous medium will, I presume, be deemed by all persons acquainted with the affi- nities of this most energetic element, to be a surer safeguard against the importation of contagion in merchandize, than the mere exposure of the goods to the air, as practised under the actual laws of quarantine. At the present crisis of the Russian cholera, the cargoes of hemp, wool, hides, &c., now in the course of arrival on the British shores from the Baltic, and immediately placed under quarantine, are so immense as to require, it has been said on official authority, the decks of ninety-five line of battle-ships for their adequate exposure. Supposing infectious fomes to exist in the merchandize, and the quarantine laws act solely on that presumption, what a formidable mass of contagion will be let loose in our atmos- phere, and what a cruel duty is imposed on the sailors im- mured in the pestilential focus ! It appears to me that the danger, expense, trouble, and delay of quarantine may be saved by a just application of the antiloimic virtues of chlorine. 92 Dr. Ure on Disinfection. The cask A, fig. 1 and 2, is destined to receive the chloride of lime and muriatic acid. The strong bleaching salt with which the Messrs. Tennant supply the London market, chiefly for the use of the paper-makers, contains on an average about 29 or 30 per cent, of chlorine gas, which it most readily gives out on the affusion of any liquid acid. I find that one pound of such chloride requires for saturation of the lime, one pint (imperial measure) of the muriatic acid of the London shops, of specific gravity 1 . 160, and evolves a cubic foot and a half of pure chlorine. This volume diluted with about twelve times its bulk of air, is adequate to the disinfection of a small apart- ment. It will be convenient in practice to introduce at once into the cask A by the hole B, six or seven pounds of the chloride, diffused among seven or eight pints of water, and then to call forth the chlorine as it is wanted for distribution, by successive affusions of muriatic acid through the syphon-funnel C, remembering that every pint of the acid will disengage about a cubic foot and a half of the chlorine. The gas thus liberated will pass along the horizontal pipe D, fig. 1, into the side of the wide vertical pipe E, and falling down into the ventilating vessel, will by the motion of its central fanner F be diluted with air in any desired measure, according to the velocity of the rotation. The air of dilution is drawn in at the axis through the open upright pipe E, and the mingled gas is blown forth through the pipes G G, whence it may be conducted and applied whithersoever the operator may choose, upwards, down- wards, or horizontally, by connexion with wooden or leaden pipes of communication. Fig. 1 exhibits an apparatus, which may be got up by any ship-carpenter in a day or two with a couple of casks, one small and the other large. This has been actually done at Woolwich. Instead of turning round the axis H of the fanner, by a horizontal motion of the hand, it may be made to revolve more conveniently by a vertical motion, provided the upper end of the axis be furnished with a couple of bevelled-toothed wheels, placed at right angles to each other, as shown by the dotted line L. The stop-cock M, serves to draw off a phial- full of the gaseous mixture, for analysis, by water or milk of lime. Dr> Ure on Disinfection. 93 Fig. 2. j J) tfi 1C L Fig. 2 is a more powerful and convenient form of the same apparatus, for disengaging chlorine, for diluting it with air, and for propelling the mixture along pipes with very considerable velocity, so as to ensure its thorough diffusion among the tim- bers of a ship, and bales of merchandize, however closely stowed. Every ship of war should be provided with such an apparatus on each of its decks, and a few minutes working of it would sweeten and disinfect, infinitely better than an hour's combustion of gunpowder wetted with vinegar, 4he delusive fumigation at present practised in the navy, under the appro- priate title of the Devil, the patron of falsehood. The slightest consideration of the gaseous products of burning gunpowder, shows that they can exercise no decomposing influence what- soever on contagious or fermentable filth, which chlorine unquestionably does. In fig. 2, the orifice B of the gas gene- rator is tubular, and rises about 18 inches high, so as to pre- clude the chance of the relatively dense chlorine overflowing, to the annoyance of the operator. But a few turns of the fanner will draw off the chlorine from A, however quickly it may be evolved. Through the pipe B, the chloride, previously mixed with water, is introduced, and by the syphon-funnel 94 Dr. Ure on Disinfection. C, the muriatic acid is to be poured in at proper inter- vals. This syphon may, probably, in the present case be dis- pensed with, and the acid may be introduced at B. The dis- engaged gas will flow off along the horizontal pipe D, into the fanner F F. When its vanes are made to revolve, atmospheric air will enter freely by the open pipe B, and passing across the vessel A, will dilute the chlorine to any degree. The mixed gases will be drawn in through the pipe D, and projected with centrifugal force through any outlet in the circumference of the blowing cylinder F. The horizontal axis of the fanner revolves at one end in the conical bush of a step or stirrup I, and at the other in a stuffing-box K. With this apparatus, chlorine may be readily propelled in any state of dilution, in any quantity, and in any direction, through apartments of any kind. Such an effective application of this anti-putrescent antiloimic element will infallibly exercise an expurgatory influence, no less sweetening to the senses, than salubrious to the system ; and ought to banish for ever the sham or mis- directed agency of chloride of lime or chlorine, with which medical men have so often deceived themselves and the pub- lic *. Wherever chlorine has failed to extinguish infectious fomes, the operator, and not the chemical agent itself, has been in fault. Let us suppose, for example, that the fetid air of a dissecting-room is to be sweetened ; and that this is attempted by setting on the table or floor a few saucers filled with chloride of lime. If the air remain fetid, is chlorine to be deemed inert and inefficacious ? No, surely ; for the operation was unskilfully performed. Thus also a small portion of chlo- rine, liberated on the floor of an apartment containing beds and furniture, may never rise in adequate force to the line of the walls where contagious virus may lurk. This remark is peculiarly applicable to the less fugacious infections, as the variolous, which require an energetic dose of chlorine. In fine, one rule may serve for the bleacher and disinfector by this element ; that is, to employ it in doses proportional to the stubbornness of the colouring or morbific matter. * Mr. Faraday's elaborate fumigations of the Milbauk Penitentiary do not fall under this censure. Dr. Ure on Disinfection. 95 The distribution of dilute chlorine through the cargo of a ship, and the due impregnation of the interior of the bales, may be easily accomplished by the above-described apparatus. From the pipes G G, tubes of lead, leather, or the water- proof double cloth, are to be led down a few feet into the hold, under the main hatchway, so that by the action of the fanner the mingled airs may be driven through every interstice, till they envelope every package. The quantity of chlorine, and the continuance of the operation, must be regulated by the capacity of the ship, and the nature of the bales ; but in general a couple of hours will suffice. All the openings in the deck should be carefully closed, except a small one near the stem and another near the stern, to permit the discharge of the atmospheric air and the ready circulation of the disinfecting gas. Eventually, traces of chlorine issuing from these openings will be observed by the smell or by the white cloud surround- ing a feather moistened with water of ammonia (spirits of hartshorn). The process may now be regarded as complete ; and after the interval of a few hours, all the hatchways and windows may be thrown open, and a free ventilation given to the ship. The residuary chlorine in its discharge into the air being wafted round the bodies of the sailors will disinfect their dress, and give final security against the importation of conta- gious fomes. An apartment may be conveniently disinfected by placing on a shelf or support near the ceiling a small basin or pipkin, containing chloride of lime, having set over it a glass or earth- enware funnel with muriatic acid diluted with about its weight of water ; the beak of the funnel being partially closed with a cork, so that the acid may drop slowly down on the chloride. Eight ounces of good chloride thus treated with ten ounces of muriatic acid, will suffice to fumigate and sweeten the air of a common-sized chamber. After the preceding observations, it will not be expected that I should ransack medical repositories, in proof of the anti- loimic powers of chlorine. But less fallacious evidence may be found. In the neighbourhood of the city of Glasgow, there are several large factories, the atmosphere of certain parts of which has been for a long series of years more or less 96 Dr. Ure on Disinfection. impregnated with chlorine ; I allude particularly to the che- mical works of Messrs. Tennant, at St. Rollox, to those of Messrs. White, at Shawfield, and to Messieurs Monteith's calico-print field, at Barrowfield. In the last- mentioned esta- blishment, a great many tons of chloride of lime were for many years treated every week with sulphuric acid, in order to obtain a strong aqueous solution of chlorine. When the sulphuric acid was poured into the clear watery solution of the chloride, contained in a large leaden cistern, a very consider- able quantity of chlorine gas escaped into the air, which com- municated its peculiar odour to the whole vicinity. Chlorine was also continually emitted from the above discharged liquor, in the course of its application to Turkey-red cloth, for pro- ducing the white figures of Bandana calicoes. Mr. George Rogers, the very intelligent conductor of this magnificent esta- blishment, has just favoured me with the following letter rela- tive to the anti-contagious influence of chlorine. * My dear Sir, — In answer to yours of the 24th, I have long been convinced of the efficacy of chlorine in purifying con- taminated or foul air, and in arresting the progress of conta- gious diseases, more particularly typhus. During the long period of thirty years that I have conducted this establishment, with a population of two or three thousand, including their families, I am not aware of a single case that could be classed as contagious ; and in many hundred cases in which I have recommended chlorine in the village (Barrowfield), its good effects have been apparent in arresting the progress of typhus and other fevers. — * I am, my dear Sir, * With much respect, yours, (Signed) f GEORGE ROGERS.* < Dunoon, 31st June, 1831.' Mr. White, who has given up making chloride of lime for a good many years, and who has no interest in the sale of the article, writes me, 26th June, 1831, as follows : — ' All that I can state is merely the impression among our workmen, of their total immunity from fever ; — and this im- pression is justified by the circumstance, that while typhus was Dr. Ure on Disinfection. 97 prevalent in the neighbourhood, none of the workmen employed in the manufacture of chloride of lime were ever its victims.' (Signed) • JOHN WHITE/ As Messrs. Tennant, the original patentees of chloride of lime, are also the greatest manufacturers of it in the world, their testimony might be received as that of interested persons. But the following document from Dr. Corkindale, physician to the gaol of Glasgow, and celebrated for his skill in medical jurisprudence, is^above any such suspicion. ' Glasgow, 1st July, 1831. 1 In the year 1824, a suit was brought against Mr. Tennant's chemical works at St. Rollox, on the score of nuisance, pro- ceeding on the allegation that the fumes arising from the processes there carried on were injurious to the health of the neighbourhood. Around the works there are houses for the accommodation of about twelve families of the workmen. These persons have continued to reside there for various periods from two to twenty years. I examined the condition of these people, and made inquiries as to the history of their health during their residence, as detailed by themselves. I found that their condition, in this respect, was nearly the same as other persons of the same rank of life, in ordinary situations ; but it was the uniform statement of the whole of them, that no person residing on these premises had been affected with typhus at the different periods when that epidemic was very prevalent in Glasgow. It was evident from inspection that this immunity was not owing to superior cleanliness and ventila- tion, for the apartments were as dirty and crowded as the ordinary habitations, where I know typhus had prevailed. The vapours from the works were various, but by far the most pro- minent was chlorine, rising both from the preparation of the chloride of lime, and from the treatment of the residuum for the manufacture of soda. (Signed) ' JAMES CORKINDALE, M.D., LL.D.' I have been favoured by M. d'Epinay, agent of the island of Mauritius to the British government, with an excellent VOL, II. AUG. 1831. H 98 Dr. Ure on Disinfection. account of the introduction into that island of the Oriental cholera, which, having recently transmigrated the middle of Asia and the north of Europe, now desolates the western provinces of Russia, and hovers like an incubus over our shores. The facts it relates will be found interesting and instructive in no ordinary degree. < London, June 25, 1831. ' My dear Sir, — I proceed to perform the promise I this day made of furnishing you with some details concerning the intro- duction of the cholera morbus into the Island of Mauritius. This disease was imported there by the British frigate, the Topaz, commanded by Captain Dumby. It is in its nature eminently contagious ; and although this opinion exposed the colony to which I belong to the most violent calumnies on the part of its Governor, General Darling, and to the anger of Lord Bathurst, then Secretary of State for the Colonies, I must persist in maintaining it, because it is proved by the facts about to be related. ' The Topaz arrived at Mauritius the 28th of December, 1819, having just come from Ceylon, where the cholera pre- vailed. This fact is notorious, and is indeed fully verified by the following extract from the Asiatic Mirror , published at Calcutta, the 24th of December, 1819. ' " We announce with regret that the news brought from Ceylon are very distressing. Fevers, dysentery, and the cholera morbus are spreading in an alarming manner. The 7th regiment, and a detachment of the 45th, which have been in the island only for a week, have suffered considerably; thirteen officers of the former, and thirty soldiers of the latter, having fallen victims to this terrible scourge." ' The report of the physicians who visited the frigate on its .arrival stated, "that the dysentery and the cholera morbus prevailed on board of it." ' Notwithstanding this, the Physician-General of the Forces in Mauritius and the Governor had the culpable weakness to permit communication between the frigate and the shore. The rumour being universally spread that several men of the frigate were ill of the cholera ; the representation of the Colonel of Dr. Ure on Disinfection. 99 a regiment, who opposed the patients of the vessel being car- ried to the Military Hospital ; tents mounted to receive them in the lie aux Tonneliers ; were circumstances which caused uneasiness ; and the members of the commune (parish) imparted their feelings to the Governor, who gave for answer, " that he was very sorry for them, but that he was ignorant of the laws of the colony ;" an ignorance supposable enough in a military man, but not the less reprehensible in a Governor. ' On the 5th of November, he wrote to the commune, to inform them that the Journal of the following day would contain an opinion from the Physician-General, which would render use- less every other measure relative to the disease which had pre- vailed on board of the Topaz. * On the 19th of November, two negroes fell down in the street, and died before there was time to assist them ; and the disease began to spread through the town. On the 23rd, the frigate brought- to, and visited a boat from the shore, as it came out of the harbour, oh its way to the river Rempart. The crew of this boat were soon thereafter attacked with the cholera, which they communicated to the establishment of M. Carcenau, their master, who lost forty slaves, and died himself of the same disease. This was the first plantation where the cholera showed itself, although it was six leagues from the town. It soon made the tour of the island, terrible in its first ravages, but becoming milder by degrees ; more fatal in the neighbourhood of the sea, and unknown in elevated regions. ' The communications with the island of Bourbon, thirty leagues from Mauritius, being open, the disease was not long in being carried thither. The inhabitants, taking alarm, formed immediately a cordon round the town of St. Denys, and the punishment of death was decreed against all who should dare to break through it. This scourge did not extend beyond the limits which wise and courageous men had here traced around it. * Very different was the case at Madagascar, into which the cholera was imported from Mauritius, and exercised the great- est ravages. ' It was computed that, in our island, the number of its victims amounted to a tenth of the population ; and I concur H 2 100 Dr. tire on Disinfection. in this estimate. It was chiefly among the lower classes, and persons given to intemperance, that the cholera was most fatal. ' A healthy regimen, great cleanliness, exercise, recreation, and courage, were found to be the best preservatives against its attack. Individuals who wore flannel generally escaped. The most successful remedy was saline purgatives, repeated in half-ounce doses every quarter of an hour, till the alvine discharge assumed a natural colour. ' I could enter into other details which go to fortify the opinion I have always entertained of the contagious nature of cholera ; but I think those I have adduced, and particularly what happened at Bourbon, ought to convince you that too many precautions cannot be taken against permitting commu- nications with vessels coming from districts infected with the malady. Believe me to be, my dear Sir, * Your devoted Servant, (Signed) ' AND. D'EPINAY.' From the same. ' July 7, 1831. * I told you that, in the Isle of France, during the cholera, we employed as a disinfector a mixture of oxide of manganese and muriatic acid. We provided small phials of it, which were carried about in all the infirmaries, and by the people who entered the hospitals. They were also carried about by the women and children ; and it was remarked that none of those so protected by the disinfecting phials were attacked with the disease. Was this from the virtue of the composition, or from the confidence inspired by it ? I cannot answer these questions, but content myself with stating the fact. (Signed) ' AND. D'EPINAY/ %* The cask A (in both cuts) should have a plug-hole or stop-cock near the bottom (not shown in the figure), for discharging the liquid muriate of lime. — I have omitted to state that dyed silk may be treated without injury with dilute chlorine. 101 ON THE PENETRATIVENESS OF FLUIDS*. By J. K. MITCHELL, M.D., Lecturer on Medical Chemistry in the Philadelphia Medical Institute. [The generality and importance of this paper is such that we think it quite im- possible to convey any idea of it by an abstract, and feel ourselves bound to bring it before our English readers at full length.] TN 1829, I read before the Philosophical Society, a short memoir -*• on a new method of forming gum elastic into thin plates, sheets, and bags. In some instances the balloons formed by the process then described had, when filled with hydrogen gas, the power of ascending to a considerable height in the atmosphere. Those which were confined to the atmosphere of my lecture-room, at the Medical Institute, descended again after a period of time, varying from an hour to two days. The cause of the descent, which did not seem of easy explanation, became a subject of investigation. The gas might have escaped from the balloons at the ligature, or by permeating the dense wall of gum elastic, or by uniting chemi- cally with the internal surface of the latter. To free the gas from the compression to which it is subjected in a balloon, I confined it in a wide-mouthed bottle, over the aperture of which I tied very firmly a thin sheet of the elastic membrane. In a few hours the descent of the cover into the cavity of the bottle gave evidence of a diminution of the contained gas, and finally the cover was burst inwards by the pressure of the atmosphere, so great had been the rarefaction of that which remained in the bottle. On weighing the membranous cover, no gain in weight could be perceived, so that I presumed that the gas had escaped. By repeating the experiment, and covering the bottle with a small bell-glass holding atmospheric air, I found, after a time, in the latter vessel, an explosive mixture, while the contents of the bottle itself were found to be pure or nearly pure hydrogen. Evidence was thus afforded that hydrogen pene- trated the membrane not by any vis a tergo, for no pressure was applied, but by some inherent power of considerable amount. The facility of permeation appeared also much greater in the hydrogen than in the atmospheric air, which, if it entered at all into the bottle, did not penetrate in any appreciable quantity, when fully one-half of the hydrogen had made its escape. In the next experiment the arrangement of the gases was altered : common air was inclosed in the bottle, and a bell-glass confined around it in an atmosphere of hydrogen. As was expected, the * Philadelphia Journal of Medical Sciences, xiii. 36. 102 Mitchell on the Penetrati'veness of Fluids. hydrogen entered the bottle rapidly, raised up the tense membrane, formed it into a globe, and finally burst through it, and thus made its escape from the Confinement to which it had been spontaneously subjected. The minuteness of the atom of hydrogen might readily enough account for the greater facility with which it penetrated the mem- brane, but could not be considered a good reason for the energy \vith which the penetration was accomplished. A gas having a heavy atom was therefore selected for further experiment, and carbonic acid, subjected to the same sort of confinement, was found to permeate the membrane with as great power, and very much greater facility. In succession, most of the gases were submitted to the same ordeal, and all of them found, except nitrogen gas, to ex- ercise the same power, but with very different degrees of rapidity. The power was ascertained by comparison with common air, and the rate of action both in that mode and by comparison with each other. The depression or elevation of the membranous cover clearly indi- cated the escape or entrance of a gas, and when two active gases were placed one on each side of it, its rise or fall expressed the dif- ference of rate, because each was, at the same moment, in the act of permeation, as proved by many examinations of the contents of the bottle and bell-glass. Having once ascertained the rate of action of each gas relative to air, a prediction could be made as to their rate in reference to each other. Hence gases which operated on air with nearly equal velo- city, affected the horizontality of the membrane very little when placed on opposite sides of it. Thus carbonic acid and nitrous oxide act with great facility on common air, and in nearly equal degree ; and when placed on opposite sides of the membrane, penetrate it rapidly, but cause a very slow change in its position. The facts here presented warrant the conclusion, that if two gases, equally penetrant exactly, could be found, they would, under the above described arrangement, mix uniformly, without in the slightest degree altering the state of the membrane *. The greatest possible degree of effect on the membrane arises, when we place on opposite sides of it the slowest and most speedy penetrator ; for instance, nitrogen and sulphuretted hydrogen. In that case the change is immediately visible. * Subsequently having discovered that olefiant gas and arseuuretted hydrogen have, with reference to common air, exactly equal rates, they were placed on opposite sides of a membrane, with a full expectation of sustained horizontality on the part of the membrane j which was confirmed by the result. Mitchell on the Penetrativeness of Fluids. 103 As in all the previous experiments, different gases were placed in comparison, I placed the same gas on both sides, and expected, for the * sufficient reason,' no change. The experiment accorded with expectation. The membrane remained stationary. The circumstances essential to the transmission of gases through the membrane formed an interesting subject of inquiry. My first attempt was to produce a vacuum, by placing the gas in a bottle, and exhausting, by means of the air-pump, the bell-glass which covered it. The gases effected their escape from the bottles thus treated, with a velocity proportional to the rate of permeation already ascertained ; sulphuretted hydrogen passed out more rapidly than carbonic acid, and that than hydrogen. Still as some air is always found in an exhausted receiver on the finest air-pump, I passed a tube containing carbonic, acid into a Torricellian vacuum, where it very speedily escaped and caused the descent of the mer- cury. Even this experiment could not prove perfectly satisfactory, as mercurial vapour occupies the barometric vacuum. A perfectly empty bag carefully closed was placed in carbonic acid and nitrous oxide successively, without undergoing the slightest inflation. If a very small portion of any kind of air remained in the bag, inflation followed, provided the bag were exposed to a different gas. By another arrangement I obtained my object more unexception- ably. Having found, by inverting a bottle holding confined gas, and thus plunging it into mercury, that no gas escaped, and that consequently mercury could not promote or sustain the permeation of the gas, I reached my object by the following means. Closing a tall cylindrical lamp-glass at one end with gum elastic, and filling it with mercury, it was placed, so filled, on the shelf of the mercurial trough, having the end closed by the membrane uppermost. Through this fine film the mercury could be plainly seen in close contact with its under surface, while the deep depression of the membrane showed the power of the column of mercury by which it was drawn down. By leaving it in the air, or by placing over it. a bell-glass of any gas, more slowly, but at their settled rates, the gases penetrated the membrane and accumulated in the cylinder, thus permitting the descent of the mercury. The process continued long after the mercury had abandoned the surface of the membrane, and the space was occupied by the gas, in, of course, a rarefied state. It became then evident, that anything which could remove the gas from the surface of the membrane at which it had arrived by penetration, would continue its transmission. Of course then 104 Mitchell on the Penetrativencss of Fluids. agents chemically attractive of a particular gas, when placed be- neath the membrane, would promote its permeation. In fact, lime water and solution of baryta were rapidly carbonated by the trans- mission of carbonic acid, and sulphuretted hydrogen almost instantly precipitated the lead of the acetate placed in solution on the opposite side of the membrane, which became black on the side of the solu- tion. A neater mode of performing this experiment is the following: Inject by means of a gum elastic bottle and pipe, into a very small bag of gum elastic, stretched until fully transparent, a solution of the substance to be acted on. Carefully tied, washed, and dried, the bag is to be passed up through mercury into a receiver holding the gas, which for solution of baryta should be carbonic acid, and for that of acetate of lead, hydrosulphuric acid. In a few moments, in the former case, a white coat is seen to completely line the internal surface of the bag, and in a few minutes to fall down and accumu- late at the bottom of it. In the latter case, the inner coat is dyed indelibly black. In either case, if water be alone placed in the bag, it will absorb a considerable quantity of either of these gases, and their presence may be ascertained by the usual tests. If any suspicion had arisen that the gases escaped or entered by the route of the space included under ligature, it was dissipated by all the experiments mentioned in the last section ; inasmuch as in the first experiment, that with the lamp-glass, the gas was seen to stud beautifully the under surface of the membrane, standing on it in minute drops or bubbles, mistaken at first for water. In the « experiments with baryta and lead in bags, the whole surface was covered, the precipitation taking place only there. Especially was it manifest in the last experiment, where the inner surface was stained black, while the solution remained clear and colourless. The gas, therefore, penetrates through every part of the membrane. Being desirous of ascertaining more accurately the relative facilities of transmission, I solicited the assistance of my friend and pupil, Professor J. K. FINLEY, to whose patience, skill, and delicate manipulation, I owe much of the certainty of the following experi- ments. Having constructed a syphon of glass with one limb three inches long, and the other ten or twelve inches, the open end of the short leg was enlarged and formed into the shape of a funnel, over which finally was firmly tied a piece of thin gum elaslic. By inverting this syphon and pouring into its longer limb some clean mercury, a portion of common air was shut up in the short leg, and was in communication with the membrane. Over this end, in the mercu- Mitchell on the Penetrativeness of Fluids. 105 rial trough, was placed the vessel containing the gas to be tried, and its velocity of penetration measured by the time occupied in elevating to a given degree the mercurial column in the other limb. Having thus compared the gases with common air, and subse- quently by the same instrument, arid in bottles, with each other, I was able to arrange the following gases according to their relative facility of transmission, beginning with the most powerful : — am- monia, sulphuretted hydrogen, cyanogen, carbonic acid, nitrous oxide, arsenuretted hydrogen, olefiant gas, hydrogen, oxygen, car- bonic oxide, and nitrogen. Ammonia transmitted in 1 minute as much in volume as sulphu- retted hydrogen in 2J minutes — cyanogen, 3j — carbonic acid, 5J — nitrous oxide, 6J— arsenuretted hydrogen, 27j— olefiant gas, 28— hydrogen 37 J — oxygen, 1 hour and 53 minutes— carbonic oxide, 2 hours and 40 minutes. Nitrogen has a rate of penetration so low as to be difficult to ascertain, because there is no gas of a lower rate with which to com- pare it. Only by causing it to pass through a membrane by means of a column of mercury, is the fact of its transmission known. In that way, the quantity being compared with that of carbonic acid, its rate was found to be about three hours and a quarter*. This ex- periment, made but once, is not confidently relied on ; but the rate of nitrogen is unquestionably less than that of carbonic oxide. Chlorine immediately altered the texture of the membrane, as did muriatic acid gas, sulphurous acid, nitric oxide, and some others, so that it was impossible to reach, for their rate of penetration, accu- rate results. In every case the movement of the gas through the membrane became progressively slower, until it totally ceased ; and finally, but more slowly, the mixed gas returned, as indicated by the descent of the column of mercury. The retrogradation ceased only when the two columns came to equilibrium, or, failing the possibility of that, when the mercury in the shorter limb had reached the membrane, through which mercury has not been found able to penetrate. Acquainted with the fact, and the relative rate of the penetrative- ness of gases, the degree of force became the next subject of inquiry : * A vessel filled with atmospheric air and closed by gum elastic was submerged under water for two weeks, when it was found to contain only nitrogen gas. Pos- sibly this arrangement may furnish a new eudiometer. It offers a new mode of obtaining nitrogen gas. A phial containing atmospheric air, after being closed by a membrane, was placed in a receiver holding nitrous oxide. In about two weeks only nitrogen was found in the phial. These facts show the mechanically sluggish character of nitrogen gas : with its chemical inactivity we have been long acquainted. 106 Mitchell on the Penetrattveness of Fluids. that it was considerable could be seen by looking at the stout mem- branes broken by it. By greatly increasing the length of the taller limb of an inverted syphon, similar to the one already described, I was able to bring to bear on the common air imprisoned in the shorter limb, a very con- siderable column of mercury. Up to a pressure of sixty-three inches of mercury or rather more, equal to more than the power of two atmospheres, the penetrative action was found capable of conveying the gases, the subject of the experiment, into the short leg, through the gum elastic membrane. The entrance of the gas into the short leg was expressed by the ascent of the long column of mercury in the other, which as it entered, it was compelled to heave up. At the height of sixty-three inches, the membrane, though supported by cloth, could scarcely sustain the weight, and would not bear any increase of height. Although, therefore, at present, I do not know the limit of this power, I believe it will be found very much greater, because the power of the column which was tried did not, until a leak was sprung, seem to very sensibly affect the rate of entrance. To the mind of a physician, the repetition of the foregoing experi- ments, substituting animal membranes for gum elastic, would natu- rally suggest itself. Should animal membranes present the same phenomena, the interest of the investigation would be vastly en- hanced, and a very important service done to the cause of ' Physi- ological Medicine.' That animal membranes would act in the same manner was rendered probable by the well-known experiments of PRIESTLEY, who affected by means of oxygen the colour of blood confined in a bladder. It had also been observed by him that a closely tied bladder, containing hydrogen gas, is found, after a considerable lapse of time, to contain only atmospheric air, and that in quantity perhaps equal to the hydrogen lost. Several other facts of the same kind are detailed by him. Finally in the Journal of the Royal Institution, I find the following * Notice of the Singular Inflation of a Bladder. By THOMAS GRAHAM, A.M.,F.R.S.E., Lec- turer on Chemistry, Glasgow/ * In the course of an investigation of mixed gases through capil- lary openings, the following singular observation was made. * A sound bladder with stop-cock was filled about two thirds with coal gas, and the stop-cock shut ; the bladder was passed up in this flaccid state, into a bell-jar receiver, filled with carbonic acid gas over water. The bladder was thus introduced into an atmosphere of carbonic acid gas. In the course of twelve hours, instead of being in the flaccid state in which it was left, the bladder was found distended to the utmost, and on the very point of bursting, while most of the carbonic acid gas in the receiver had disappeared The Mitchell on the Penetrativeness of Fluids. 107 bladder actually burst in the neck, in withdrawing it from under the receiver. It was found to contain thirty-five parts carbonic acid gas by volume in one hundred. The substance of the bladder was quite fresh to the smell, and appeared to have undergone no change. The carbonic acid gas remaining without in the bell-jar had acquired a very little coal gas. * The conclusion is unavoidable, that the close bladder was inflafed by the insinuation of carbonic acid gas from without. * In a second experiment, a bladder containing rather less coal gas, and similarly placed in an atmosphere of carbonic acid gas, being fully inflated in fifteen hours, was found to have acquired forty parts in one hundred of this latter gas, a small portion of coal gas left the bladder as before. 1 A close bladder, half filled with common air, was fully inflated in like manner, in the course of twenty-four hours. The entrance of carbonic acid gas into the bladder depends, therefore, upon no peculiar property of coal gas. The bladder partially filled with coal gas did not expand at all in the same jar containing common air or water only. * M. Dutrochet will probably view, in these experiments, the dis- covery of endosmose acting upon aeriform matter, as he observed it to act upon bodies in the liquid state. Unaware of the speculations of that philosopher, at the time the experiments were made, I fabri- cated the following theory to account for them, to which I am still disposed to adhere, although it does not involve the new power. ' The jar of carbonic acid gas standing over water, the bladder was moist, and we know it to be porous. Between the air in the bladder and the carbonic acid gas without, there existed CAPILLARY CANALS through the substance of the bladder filled with water. The surface of water at the outer extremity of these canals being exposed to car- bonic acid gas, a gas soluble in water would necessarily absorb it. But the gas in solution, when, permeating through a canal, it arrived at the surface of the inner extremity, would rise as necessarily into the air in the bladder and expand it. Nothing but the presence of carbonic acid gas within could prevent the disengagement of that gas. The force by which water is held in minute capillary tubes might retain that liquid in the pores of the bladder, and enable it to act in the transit of the gas even after the pressure within the bladder had become considerable.' A careful perusal of Mr. Graham's notice will excite in every one who knows the value of experimental interrogation, an expres- sion of surprise, at the failure, on the part of that intelligent and ingenious chemist, to pursue, in the only true spirit of science, the investigation of a principle, one of the most striking manifestations of which had thus been placed conspicuously before him. Content with a single additional experiment, he comes, in the ancient method, to immediate conjectural explanation, and has thus lost an easy opportunity of making a beautiful, and, perhaps, extensively useful 108 Mitchell on the Penetrativeness of Fluids. discovery. Made at an earlier period, his observation was published in the Journal for October, 1829, and has since attracted appa- rently no scientific attention. Such is usually the fate of the most pregnant facts which are not perceived to bear on some generality. This one passed from my mind along; with all the other isolated phe- nomena of that number of the Journal, and only shone importantly when illuminated by the reflected light of an extensive principle, subsequently developed. These remarks are made, not to throw any discredit on the character of the accomplished gentleman to whom they refer, but to correct the baneful error of ancient dogmatism, which yet weighs so heavily on the cause of nature and truth. It was true that the carbonic acid entered a closed bladder, and that too with power, and it was equally true, that oxygen had done the same thing in the experiment of Priestley, and that, in his hands, even common air had penetrated to replace hydrogen in a similar viscus, and yet he ascribed the phenomenon observed by him to the capillaries, and the conducting power of aqueous canals. In what manner the power of ' rising into the air' was given, and whether it was dependent on the force of water, or some other cause, does not and could not be made to appear from the single fact, as presented by Mr. Graham. A very little practical interrogation, following the word just uttered by nature, would have obtained an answer fraught with new and important truth. But to return to the immediate subject of this essay. — Analogy, the experiments of M. Dutrochet, and the observations of Priestley and Graham, gave me almost the certainty of finding animal mem- branes performing relatively to the gases the same function which belongs to those formed of the inspissated juice of the Jatropa elas- tica. Accordingly, each gas was subjected to the action of animal membranes, which replaced the gum elastic at the mouth of the short limb of an inverted syphon. Dried bladder, and gold-beater's skin, moistened to cause an approach to a normal state, and sections of various recent tissures, were successively tried, and found to act on the gases in the manner and order in which they were affected by gum elastic. The more recent the membrane, the more rapid and extensive the effect produced ; and in living animals the trans- mission was very rapid. Besides the estimates of comparative movement made with the syphon, experiments in a different manner were resorted to, to more clearly show the general truth. Thus a piece of the strong intestine of a goose connected with the oesophagus and gizzard, being par- tially inflated with common air, and firmly tied, was left in an Mitchell on the Penetrativeness of Fluids. 109 atmosphere of carbonic acid, where in less than ten minutes the inflation caused it to burst. On repetition of this experiment and examination before fracture, a very large quantity of carbonic acid gas was discovered to have entered the intestine. Crop, bladder, &c. &c. of recently killed animals produced exactly similar results. Perhaps the following experiment will be esteemed even more satis- factory. Carefully removed from the chest of a snapper, (Testudo serpentaria^) its lung was partially inflated with common air, and confined there by a ligature on the tracheal tube. Exposed in this state to an atmosphere of carbonic acid, or nitrous oxide, it became very soon fully inflated by the gas to which exposed, as subse- quently proved by chemical examination. Less than half an hour of exposure sufficed for the full inflation of the lung, which was removed only when it threatened to burst. Containing a portion of nitrogen, it was left exposed all night to an atmosphere of oxygen, yet scarcely enough entered to signify its presence ; in quantity superior to that which is held in atmospheric air. A taper appeared in it somewhat brighter than before its immersion. In a subsequent experiment, the two lungs of a snapper having been extracted, were inflated respectively, with common air, and carbonic acid gas. So prepared, each lung was surrounded by a bell-glass containing an atmosphere of the other gas, so that common air surrounded the carbonic acid, et vice versa. That lung which contained common air soon burst by the infiltration of carbonic acid, while the other collapsed by its escape. In concluding the series of experiments on the question of fact, some were made on living animals. A quantity of solution of acetate of lead having been thrown into the peritoneal cavity of a young cat, sulphuretted hydrogen was discharged from the pipe of the gene- rating retort, directly into the rectum. In four minutes the poi- sonous gas killed the animal, giving to it, because of enormously dilated pupils, a very wild aspect. Instantly on its death, which was itself an affair of a moment, the peritoneal coat of the intestines, and the walls of the cavity in contact with them, were found lined with a metallic-looking precipitate, adherent to the surface, and sus- ceptible of removal by nitric acid, moderately diluted. It was the characteristic precipitate of sulphuretted hydrogen when acting on lead. When, in another experiment, the abdominal cavity was almost instantly opened, only the intestines and stomach presented the bronzed aspect ; the peritoneum of other parts, and the bladder, appeared of their natural colour, thus proving that the gas had in- filtrated, and not passed through any rent or fracture, an event 110 Mitchell on the Penetrativeness of Fluids. which would have stained the whole of the lining membrane of the cavity, and dyed the bladder. This experiment forcibly reminded us of that where the internal surface of a gum elastic bag holding lead water, was stained black by sulphuretted hydrogen, while the solution continued pellucid. In another experiment on a cat, a solution of acetate of lead was placed in the thorax, and sulphuretted hydrogen in the abdomen. Almost immediately, on the entrance of the sulphuretted hydrogen into the abdominal cavity, death ensued, with the same dilatation of pupil as before. On inspecting the thoracic side of the dia- phragm, which was done as quickly as possible, the tendinous part of it displayed the leaden aspect of the precipitate by sulphuretted hydrogen. Many years ago, in 1823, while engaged in investi- gating MAGENDIE'S theory of venous absorption, I coloured the diaphragm of a living cat blue, by placing a solution of prussiate of potash on one side, and that of sulphate of iron on the other. At that time I supposed the effect to be vascular, but the experiments on membranes of gum elastic afford an explanation which more rationally refers it to organic molecular infiltration ; for, in such membranes, vessels cannot possibly exist at all ; and as animal membranes act in a manner so perfectly accordant with that of the coagulated vegetable juice, it would be judging against evidence to refer their agency to widely different causes. At the same rela- tive rates, with the same power, and that a great one, they could scarcely act, in obedience to causes so dissimilar as those alluded to. Every one who has read the beautiful memoir of Dutrochet, on * L'agent immediat du Mouvement Vital, §*c.,' and who has, as nearly all have, suffered their belief to be swayed by his eloquence of fact, method, and style, will, on a cursory glance at the experi- ments detailed in this paper, refer them to the * NEW POWER* so ably contended for by the French naturalist. That they depend on the same power cannot be reasonably questioned, whether that power be one long known or recently discovered. In his experiments made exclusively on liquids, and developed with surpassing good fortune and sagacity, he proved the transmission of liquids through animal membranes, and saw them penetrating, too, at different rates, some solutions passing rapidly, some with greater slowness, some in scarcely appreciable quantity, and some never passing at all. Their force, too, he found to be of estimable amount. In fact, every aspect of the two sets of experiments tends, more and more clearly, to induce a reference of them to one and the same cause, whatever that cause may be. Although the facts presented by him demon- Mitchell on the Penetrativeness of Fluids. Ill strate all this, yet M. Dutrochet did not perceive it, as is evident from his reference of the phenomena to a source to which, in latter years, the French naturalists and philosophers have been accustomed to look with almost superstitious reverence. Electricity is the great key of scientific explanation ; and the theory of Du Fay is relied on, though badly itself sustained, as the point d'appui of almost all other theories. M. Dutrochet has accordingly ascribed the trans- missions to that power, and supposed, in the very teeth of some of his most striking facts, that the current was from a less dense to a more dense fluid, or from positive to negative, dependent not on an inherent power of infiltration, and of course for the same membrane always the same, but varied, or even inverted, at pleasure, by arrangements productive of supposed electrical powers. He says, p. 139, ' Ces re'sultats nous font de"jk pressentir que 1'impulsion qu'eprou- vent les liquides dans ses experiences, depend d'un courant dlec- trique determine par le voisinage de deux fluides de densite' ou de nature chimique diffe'rentes, fluides que se*pare imparfaitement une membrane permeable. Cette membrane ne joue evidemment aucuii role propre dans cette cir Constance, ; elle ne fait fonction que de moyen de separation entre les deux Jluides auxquels elle est cepen- dant permeable : les liquides la traversent, soit dans un sens, soit dans Vautre, au gre de r action reciproque des deuxjliddes qui baignent ses parois opposees.' As he used water and solutions in water, by which the former became denser, he found, as might be expected, that it infiltrated the tissue more readily than most of its solutions ; hence, in such cases, the water penetrated more quickly than they, and the current usually set most rapidly from less dense to more dense. But when he used essentially different liquids, he yet found the water going through at Us high rate, as we perceived to be the case with sul- phuretted hydrogen and ammonia. Water traversed the animal membrane rapidly to join alcohol, which, according to his electrical theory, should not have been the case, as the alcohol is less dense than water. For this and some other exceptions Dutrochet attempts to account, by reference to influence derived from chemical quali- ties. If, however, as in the case of the gases, two liquids of different rates of penetrativeness be placed on opposite sides of an animal membrane, they will in time present the greater accumulation on the side of the less penetrant liquid, whether more or less dense, but will finally thoroughly and uniformly mix on both sides, and at 112 Mitchell on the Penetrativeness of Fluids. length, if any pressure exist on either side, yield to that and pass to the other side. r As some substances have no penetrativeness, such as milk or blood, or at least their solid parts, the water placed on the opposite side of the membrane alone moves, and it is only after the decom- position by putrefaction, and consequent formation of a new fluid having penetrant properties, that any current sets in the direction opposite to that of the water. To prove this, it is only necessary to show that alcohol penetrates gum elastic much more rapidly than water ; and that, therefore, when that kind of membrane is inter- posed between them, the greater current is from alcohol to water, and not from water to alcohol. A hollow glass cylinder, open at both ends, was closed com- pletely by two membranes of gum elastic, having been previously perfectly filled with alcohol. It was then sunk in the large pneu- matic trough of my laboratory, where it remained one week. At that time it presented a concavity at each end, of decided depth, proving the escape of a considerable quantity of alcohol. On the other hand, a similarly prepared vessel filled with water and sub- merged in alcohol presented at the end of a week well-marked convexities, demonstrating the insinuation of alcohol. If it be con- tended that the nature of the membrane affects and even reverses the electrical state, it may be well said in reply, that there is no analogy for that, and moreover, the same membrane acts under the movement of gases precisely as an animal membrane. The suppo- sition would invest it with a most Protean character. In making experiments for the preparation of gum elastic by ether, that liquid was found to readily infiltrate its tissue. Alcohol has been already shown to penetrate it better than water, and water enters its substance so slowly, that a bag of a thinness productive of almost perfect transparency, and containing four ounces, two drams, and fifty-seven grains, lost by evaporation but eight grains in the first period of twenty-four hours, and fifteen grains during the next three days. Viewing these facts, a prediction was founded on them relative to the effect of placing ether in contact with one surface of such a membrane, while alcohol or water occupied the opposite sur- face. As was expected, the greater quantity accumulated on the side of the less penetrative substance, and the ether always caused, by its transmission, an augmentation of liquid on the side of the alcohol or water. Using animal membranes, facts of a similar kind, previously ascertained, led us to anticipate the opposite result. Ac- cording to expectation, water being most penetrative, passed through Mitchell on the Penetrativeness of Fluids. 113 so much more rapidly than ether or alcohol as to swell the amount of liquid on their side. When alcohol is largely diluted with water it penetrates an ani- mal membrane more easily itself, and offers to the pure water which reaches it from the opposite side less invitation to infiltrate it, ac- cording to a law of progressive diminution, pointed out by our expe- riments on gases. Such a diluted portion of alcohol placed by M. Dutrochet in his endosmometer, and raised above the level of the pure water on its outside, found, in the force of the higher column, sufficient cause for its escape, which continued until the level was reached, when action apparently ceased. If the level be obtained at the commencement of the experiment, either no appreciable change is observed, or the movement is unquestionably in a direc- tion contrary to that stated by Dutrochet. So, when gases are permeating in opposite directions any interposed membrane, the penetration soon begins to lessen, because there is on either side less porosity unoccupied, and there is also in them the repellent character of their gaseous state. M. Dutrochet reconciles these apparently contradictory facts to his system, by supposing chemical influence to produce the first, and electricity the second. In either case, he does not appear to dream of independent and original pow- ers of penetration, by which the liquid comes through to the opposite side of the membrane, remaining in its tissue, or passing on by a similar power of infiltration into new matter, or, such matter being absent, accumulating on that side by the influence of mechanical power, or electrical excitement, or chemical combination, truths adequately demonstrated by my experiments on gases. The blinding effect of preconception on the most philosophic and candid mind can perhaps have no better exemplification than is afforded by what M. Dutrochet says relative to the point of accumu- lation, when a diluted acid and water were placed on opposite sides of an animal membrane. As alkalies produced towards them a cur- rent for the support of his electrical theory, acids should be found to set the current towards water, and he found it so. In my experi- ments, the greater current was always towards the acid, and not from it ; and I find that Dr. WEDEMEYER (Untersuchungen iiber der Kreislauf des Bluts, &c.) has made the experiment with a like result. On reference to Dr. TOG NO'S experiments (Amer. Journ. of Med. Sci.), which were chiefly repetitions of those of Dutrochet, we perceive that he does not seem to be satisfied perfectly with the report of Dutrochet on this subject. Let any one desirous of testing this matter, tie a piece of animal membrane over the end of a hollow Voi« II. AUG. 1831. I 114 Mitchell on the Penetrativeness of Fluids. glass cylinder, partially fill it with diluted sulphuric acid, and place it in a vessel of clean water, so as to bring the two columns to a level. In a few hours the column holding the acid will rise con- siderably above that of the clean water, proving the greater current to set from water to acid, and not from acid to water. Tests, how ever, show that some acid does pass the membrane *. To feel assured of the error of Dutrochet, I repeated the experi- ment in another form. A tube of five-sixteenths of an inch in dia- meter, ending in a funnel-like extremity of an inch and a quarter, was covered at its broad end by animal membrane, then partially filled with diluted acid, and placed, membrane downwards, in clean water, so as to bring both columns to a level. INSTANTLY the rise in the narrow tube was perceptible, and amounted to nearly half an inch in half an hour. Reversing the order, by placing the clean water in the tube, and the diluted acid without, as sudden and pro- gressive a descent of the column of clean water was observable. Tests, after a short time, betrayed the percolation of some acid, and, finally, in every case the liquid became uniformly acidulous through- out, and the two columns fell to a common level — an event which may always be expected, unless the combination produced by trans- mission is not penetrant. Water may be removed from the surface of a membrane at which it has arrived in many and various methods. Invitation may be given to it by a column of mercury contained in a hollow cylin- der closed above by animal membrane. Water readily passes through, may be seen studding in drops the surface of the mercury, gradually covering the under side of the membrane, causing at length the separation and descent of the mercury, and continuing to enter the cylinder until the mercurial column sinks to the level of the general contents of the trough. There the action ceases, but if the water placed above the membrane be now removed, the mercu- rial column will again rise, and all the water having escaped through the membrane by the process of infiltration into the atmosphere, the mercury will be finally seen in close contact with the membrane from which it had receded. Sometimes before the completion of the process a change takes place in the condition of the animal matter, and some gas being introduced below suspends the ascent of the mercury f. * This fact I demonstrated to Dr. Togno. f A new hygrometer was suggested by this experiment, of which I purpose giving an account to the Philosophical Society. Mitchell on the Penetrativeness of Fluids. 115 A sponge slightly moistened, or dry oat-meal, or any other ab- sorbent, placed by means of a moderate weight closely in contact with the membrane, will, by absorbing the water, cause its continued permeation. Even vis a tergo, as in the instance of the gases, will produce infiltration where there exists no other cause of penetration. Over the end of the short limb of an inverted syphon was tied a piece of bladder, and over that, and in close contact with it, was also secured a piece of sheet caoutchouc. Water was then placed in the short limb in communication with the bladder, and thus left for a few hours without compression. No appreciable amount of infiltration ensued. But, in a short time after a column of mercury had been placed in the long limb, water was plainly seen to insinuate itself through the bladder, and to raise up and separate from it the more elastic membrane which surmounted it. After all the water had passed into the space between the two membranes, the syphon was placed in its ordinary position, the end of the long limb resting in the mercury of the trough. Soon the water repassed the bladder, ascended through the short column of mercury lying above it, and collected in the curve which then formed the pinnacle of the appa- ratus. Another fact, in itself important, bears forcibly against the electri- cal theory of Dutrochet. To try the absorbent power of the dermoid tissue, pieces of it in a recent state were tied, cuticle outwards, over bottles which contained common air, or carbonic acid gas. Over the bottle which held carbonic acid was inverted a jar of common air, and over that holding air was placed a jar of carbonic acid. The more penetrating gas was, in the first case, in contact with the cuticle, and in the other, with the dissected under surface of the skin. A trial of the contents, after twenty-four hours, showed that much more carbonic acid had penetrated in that apparatus where it was applied to the cuticle, than in the other. As in that case it had gone from the jar into the bottle of common air, while in the other case very little carbonic acid gas had escaped from its receptacle, I filled it again, and tied over it a piece of skin with its cuticle looking inwards. In twenty-four hours the carbonic acid was equally dif- fused through both bottle and jar. Two similar sections of intestine were slightly inflated with common air, one of them being turned in- side out. Both having been carefully tied at the ends, were placed in. identically the same carbonic acid in vessels of equal size. It was soon apparent that the one which had been inverted, filled itself I 2 ] 16 Mitchell on the Penetrativeness of Fluids. most rapidly, and although rather less than the other, soon greatly exceeded it in size and hardness. After remaining so exposed for eighteen hours, vessels of common air were placed over the dis- tended bags, when a diminution of volume became in time apparent, and was more rapid considerably in the specimen which had not been inverted. It appears, then, that the transmission of a gas is easiest where it is placed on the cuticular or mucous surface of an animal membrane, rather than on its cellular or peritoneal surface, — a fact to be kept in view in rating the transmissibility of the dif- ferent gases or liquids. The fluids should be compared under ex- actly similar circumstances, standing in the same relation to the surfaces of the membrane used. In the following experiment, made with great precaution, we per- ceive a result distinctly indicative of the superior penetrability of the cuticular surface. Over the mouths of two phials, accurately filled with alcohol, weighing, according to a Pese-Ether, thirty-five and a quarter, were tied two pieces of human skin. In one the raw side presented, in the other the cuticular side. Both were placed mouth downwards in similar specimens of water, with columns of equal altitude. After the lapse of twenty-four hours, the alcohol was exa- mined, and found to weigh more, by at least one degree, in the phial which presented the cuticle to the water. In it the ethero- meter sunk to thirty-three and a half, while in that which presented the dissected surface to the water it fell only to thirty-four and a half. The one had been reduced by the water one degree and three- fourths, and the other only three-fourths of a degree. In all these cutaneous experiments, we perceive not only the agency of the membrane itself, but even that of its respective sur- faces, so that we are not at liberty to admit the assertion respecting the action of the liquids, as independent of the influence of the inter- vening membrane. In truth, it is now manifest that the liquid, if penetrative, per- meates a given tissue at a rate dependent on the character of tissue and power of penetration. If on the opposite side there exist a sub- stance or power capable of occupying or removing it as fast as, or faster than the membrane delivers it, the actual rate of transmission will be as high as is possible ; but if not so capable, the accumulation will be at a lesser rate, and will represent the degree of permeability of the inviting substance alone. Thus, for illustration, if ether can convey away water as fast as, or faster, than the membrane can transmit it, the rate of penetration will be the greatest possible, and Mitchell on the Penctrativencss of Fluids. 117 will represent the full penetrability of that membrane by water. But if ether is less penetrable than that membrane, the rate of accumulation will not represent the power of the animal tissue, but that of the ethereal interstices, which^ on the supposition, is less. The power of this process in liquids, like that of the gases, is not yet measured. It is the power of infiltration in all such cases, and must be eminently great. Like all processes having dependence on molecular action, this one is influenced by electricity, when that is brought to bear on it, but we can scarcely, after a fair estimate of the value of facts, see anything more in the power than that of common interstitial infiltration, a power marvellously great, but insusceptible of demonstrative reference at present to any known cause. The amount of force having been shown to greatly exceed that of atmospheric pressure, we feel assured that the interstices are pene- trated not by any vis a tergo. It must therefore be attributed to some species of attraction, the force of which, as shown by the con- densation of some gases by charcoal, sometimes equals a power of forty atmospheres, or nearly six hundred pounds on the square inch, a power amounting nearly to that of steam, at its maximum density *. It is not chemical, because the quantity absorbed bears no relation to known affinities ; it is not homogeneous attraction, for it takes place solely among dissimilar substances, and often sub- verts the condition produced by that power, as in some cases of solution. After having proceeded thus far with my argument and experi- ments, I felt as if it were important, if not essential, to my positions, to test the power of gum elastic as an absorber of gases, indepen- dently of the artificial arrangements which brought different gases to the opposite sides of it. For that purpose I selected a hollow cylinder of gum elastic, with thick parietes about an inch in length. This specimen was placed in a cylindrical graduated test-glass, filled with carbonic acid gas and placed over mercury. In less than one minute the mercury began to rise, and in eight hours, during which the observer was absent, it had risen to a considerable height. A rough attempt to measure the bulk of mercury raised, and of gum elastic used, showed that nearly an equal volume of * Found by comparing the experiments of Caguard de la Tour with those of the Committee of the Institute of France. 118 Mitchell on the Penetrativeness of Fluids. carbonic acid had been absorbed by the caoutchouc. A piece of dry bladder was subjected to the same treatment, and produced a similar rise of the column of mercury. Macerated in water for an hour, and then wiped well with a dry towel, so as to obtain dry sur- faces, the same piece of bladder was again placed in the gas over mercury, and produced a diminution apparently equal in quantity to that which, when dry, it occasioned. The bulk of the gum elastic was considerably increased by the infiltration, so that, although easily placed in the glass vessel, it was of difficult removal. This fact, added to that of the thorough penetration by water of an animal membrane macerated in it, shows how much of the phenomena described in this paper is attributable to the organic molecular infiltration. The remainder of the effect is dependent on the moleculo-porous relation of the gas or liquid to the substance beyond, into which infiltration carries the permeating substance. If the recipient beyond the membrane be as active as the membrane, or more so, all that the membrane brings to its sur- face will be transmitted as fast as it arrives ; but if that recipient be pf inferior penetrability, less will pass on than the membrane could carry through, and in that case the rate of penetrativeness of the substance relative to the membrane is inappreciable. Any gas penetrates another gas better than it does any solid, hence we ob- tain for them the true rate. But liquids penetrate each other some- times less rapidly than at the rate of the transmission through the membrane. Such cases do not show the rate of transmissibility by the membrane, but of reception beyond. [To be continued.] Proceedings of the Royal Institution of Great Britain. FRIDAY EVENING MEETINGS, 1831. (CONTINUED.) April \bth. — Mr. J. F.Daniell on the Forms and Attractions of the Particles of Crystals. — The subject of this evening forms the matter of the paper at page 30 of the present Number of this Journal. The recent experiments made in Edinburgh by Mr. A. Trevellyan, on the production of musical sound during the transference of heat, by conduction, from hot pieces of metal to cold masses of lead, were repeated before the members, with apparatus brought from Edin- burgh, by Mr. Addams. April 22d. — Mr. Marshall on the Origin and Utility of Cow-pox; with the Causes of Failure in the practice of Vaccination. — Mr. Marshall introduced the subject by a short account of Dr. Jenner and his exertions. He then proceeded to notice the effects of the practice of vaccination, and the causes of its occasional failure. From tables it appeared that the annual mortality in cases of small- pox was reduced in Copenhagen from 450 to 9 ; in Prussia the average was as 12 to 1 ; Berlin, in 1819, only 25 had died, being' about 1 in 8000 ; Bavaria, in 11 years, only 5 had died ; Anspach, the disease had been completely exterminated ; Norwich, in one year the small-pox cutoff more persons than any disease, except the plague ; Edinburgh, similar havoc ; London, in one year 13,000 died; Russia, from 1804 to 1812 there were upwards of 1,200,000 individuals vaccinated. Mr. Marshall then stated the various causes of failure, as age of virus, want of care, bad selection, &c. &c. ; and the precautions under which vaccination might be considered as a thorough barrier to the small-pox. April 29th. — Mr. Faraday on Mr. Trevellyan's recent Experi- ments on the Production of Sound during the Conduction of Heat. Mr. Trevellyan had remarked that when a heated poker was laid upon a table, so that the knob rested upon the table, but the hot part upon an interposed block of cold lead, regular musical notes were frequently produced. By extending his experiments, he found that a better form than that of a poker might be used for the hot metal : a piece of brass about four inches long, one inch and a quarter broad, and half an inch thick, should have a groove of one-eighth of an inch in width, formed down the middle of one of the broad faces, and then that face bevelled from the edges 120 Proceedings of the of the groove on each side. Being now placed with the groove downwards upon a table, and shaken, it rocks to and fro, and is in right condition for the experiment. It is convenient to fasten a brass wire, terminated by a knob, to one end of this rocker, so as to act as a prolongation of an axis : it renders the whole arrangement steady and regular in its action. When this piece of metal is used instead of the poker, musical sounds are almost always produced. The surface of the lead upon which it rests should be clean. The peculiar effects exhibited in these experiments depend upon the occurrence of isochronous vibrations performed by the rocker. When by loading the rocker these are rendered slow, they become visible : but when they occur with sufficient rapidity they produce the necessary result, a musical note, of higher or lower pitch, as the vibrations or tappings are more or less numerous. It often happens that other and extraneous sounds, as those due to the ringing of the metal, the vibration of the table, or subdivisions of the whole vibrating system, mingle with the true sound produced by the blows of the rocker ; these were referred to and illustrated, and a method shown of easily distinguishing the latter from the former : it con- sisted in pressing perpendicularly with a small stick or pointed metal rod on the back of the rocker, exactly over the groove, so as to make the vibrations quicker, but not to disturb their regularity ; the true sound of the beats of the rocker immediately rises in pitch, and may be sometimes made to pass through an octave or more at pleasure, falling again as the pressure is removed. As the sound was evidently due to the rapid blows of the rocker, the only difficulty was to discover the true cause of the sustaining power by which the rocker was continued in motion, whilst any considerable difference of temperature existed between it and the block of lead beneath ; this Mr. Faraday referred to the ultimate ex- pansion and contraction, as Professor Leslie and Mr. Trevellyan have done generally; but he then gave a minute account of the manner in which, according to his views, such expansion and contraction could produce the effect. When the heated rocker is reposing upon a horizontal ridge of lead, it touches at two points, which are also heated and therefore expanded, and form two hills ; when one side of the rocker is raised, the point relieved from its contact is instantly cooled by the neighbouring portions of lead ; the expansion ceases, and the hill falls. When the rocker, therefore, is left free, the raised side descends through a greater space than that through \vhich it was lifted ; and also to a lower level than the other side : in consequence of which a momentum is given to it, which carries its centre of gravity beyond the point to which it would pass if there had been no alteration in the heights of the sustaining points. It is this additional force which acts as a maintaining power; it recurs twice in each vibration, i. e. once on each side. The force is gained by the whole rocker being lifted bodily by the point on •which it is for the time supported, and comes into play by the side Royal Institution of Great Britain. 121 of the rocker which is descending, having a greater space to fall through than that which is passed over by the mere force of its momentum during its previous rise. A curious consequence of this action is, that the force which really lifts the rocker is on one side of the centre of gravity, whilst the rising side of the rocker itself is on the other. This, however, is not the only maintaining cause or mechanical force generated by the alternate expansion and contraction of the lead. If the vertical direction of the forces be put out of considera- tion for a time, and the two points of support be examined, it will be found that whilst the rocker is quiescent, both points (with their neighbouring parts) being heated, will expand and compress the lateral portions of the lead, until the tension of the latter is equal to their own. When one side of the rocker is raised, the point that it rested upon is instantly cooled, and therefore contracts ; but as the neighbouring parts retain their tension, they move towards the contracting part, the other point of support moving with the rest. When the rocker returns in its oscillation, it reheats and re-expands the first point of support, whilst the second, now out of contact, is cooled and contracted, and the first point, therefore, moves towards the second. A necessary consequence of this mutual relation of the points is, that the one under process of heating is always moving towards the other which is under process of cooling ; and, conse- quently, towards a perpendicular from the centre of gravity ; but as it is at the same time the supporting point to the rocker, that supporting point is, by irresistible impulse, carried in a direction under and towards the line passing from the centre of gravity towards the earth, at the same instant that the centre of gravity of the rocker is, by the momentum of the latter, moving in the oppo- site direction : hence a very simple maintaining power, sufficient, whenever the rocker continues to vibrate, to compensate for the loss of force in each half of the vibration which would occur if the rocker and lead were of the same temperature. Mr. Faraday illus- trated the sustaining force of the lateral motion of the points of support, by placing a rocker on a piece of lead, and the latter on a board. A pair of sugar-tongs was held tightly by the bend against the edge of the board, so that the line from the tongs towards the rocker was perpendicular to the axis of the latter. On making the limbs of the sugar-tongs vibrate in the manner of a tuning-fork, they communicated longitudinal vibrations of equal duration and number to the board, and through it to the lead and points sup- porting the rocker ; which latter itself immediately acquired vibra- tory motion isochronous with the vibrations of the tongs, and by successive blows upon the lead produced sound: upon removing the rocker, and repeating the other parts of the experiment, no sound was produced. Experiments with other metals were then made. A piece of curved silver plate being heated and placed on an iron triblet, rocked and sang in the manner of the others ; this is an effect which work- 122 Proceedings of the ing silversmiths have long1 known. The superiority of lead, as the cold metal, was referred to its great expansive force by heat, com- bined with its deficient conducting power, which is not a fifth of that of copper, silver, or gold ; so that the heat accumulates much more at the point of contact in it, than it could do in the latter metals, and produces an expansion in that^ respect proportionably greater. Mr. Trevellyan's paper had been read to the Royal Society of Edinburgh, but is not yet published. Mr. Faraday stated that Mr. Trevellyan had very liberally allowed him the use of a written copy. May 6th. — Mr. Lindley on the Pitcher Plant. — On this evening Mr. Lindley brought before the meeting some illustrations of the plants that have those remarkable appendages which botanists call Pitchers or Ascidia. He remarked that appendages in which water or fluid collects have been noticed in a variety of plants ; but that he did not pro- pose, upon the present occasion, to advert to any in which the pitchers do not form a striking and principal feature of the vegeta- tion. These he stated to be the following. Firstly, all the species of Sarracenia, little North American swamp-plants, in which the pitchers are hollow, green, sessile bodies, arising from the crown of the plant, and surrounding the scape ; they are furnished with a projecting membranous wing on their face, are terminated with a green leaf-like lid, and are covered inside with numerous inverted hairs. The second kind of pitcher plants was said to consist of the various species of Nepenthes, which are found growing in the marshes and ditches of China, and the damper parts of India. In these the pitchers were described as hollow bodies, similar to those of Sar- racenia, and, like them, furnished with a sort of lid, but differing in having a long stalk, which in the lower half is leafy and flat, and in the upper, where it joins the pitcher, cylindrical and twisted ; and also in proceeding from the stem in the place of leaves, instead of forming a cluster of pitchers, arising from the base of the scape at the surface of the ground. A third kind, a native of swamps in New Holland, the Cepha- lotus follicularis, was compared to Sarracenia, in regard to the organization and position of its pitchers, but was stated to be remarkable for the presence of flat leaves of an elliptical figure among them. All the foregoing were said to be either herbaceous plants, or at least not more than undershrubs; that is in the case of nepenthes, inter- mediate between herbaceous and shrubby. Trees or climbing plants were next mentioned, as sometimes having appendages to which the name of pitchers might be applied, although destitute of the remarkable lid which exists in all the kinds previously named. Thus in the Dischidia Rqfflesiana and Clavata, two plants found the one in the Indian Archipelago, and the other on the coast of Royal Institution of Great Britain. 123 Martaban, the pitchers are in the form of large yellowish-green bags, hanging in bunches from the slender woody stems by which the species climb to the tops of trees ; and in Marcgraavia umbellata, and in the genus Norantia, the former a West Indian climbing plant, the latter small trees found in the midst of rocks and mountains in Brazil, especially in the Minas Geraes and Serra Dorada, the pitchers are small, coloured, hollow bodies, occupying the place of bracteee, and hanging down or standing erect among the flowers. These forms of pitchers were illustrated by highly magnified drawings, and by beautiful specimens furnished for the occasion by Dr. Wallich. With regard to the uses for which these curious organs are destined, it was observed that a variety of opinions had been enter- tained, among which it was difficult to say which was most unsatis- factory. Thus Rumphius supposed that the pitcher of Nepenthes was intended as the nest of a sort of shrimp frequently found in it; Morison considered it in Sarracenia as an * operculum divina pro- ' videntia ad obtegendam et defendendam plantam a pluviarum ' injuriis statutum." Linnaeus compared Sarracenia to a water-lily growing in dry ground, and thought its pitcher was a reservoir of rain ; and he supposed that in Nepenthes the pitchers were reservoirs of water, to which animals might repair in time of drought, their lid being especially destined to close up the mouth of the vessel, and thus to prevent evaporation. Sir James Smith thought that in Sar- racenia the pitcher was intended for an insect-trap, because insects are often found in the water, and because the stiff inverted hairs that line it are peculiarly well adapted to prevent the escape of insects once inclosed in it ; and that the putrescence of the insects was converted into the food of the plant. The objections to these theories were obviously, that they either depend upon data which are actually false, as in the case of Linnaeus, when he fancies that a plant which really grows in marshes is a native of dry situations ; and that a lid, which never alters its position when once raised from the pitcher, has a power of contracting and closing up the mouth to prevent evaporation ; or else upon unsupported hypothesis, as in the case of Smith's opinion, that the putrescence of insects generates food for the plant ; and of others who think that the pitchers are reservoirs of water for the use of animals in dry weather. With regard to this latter supposition, it was remarked that, in Sarracenia, the water could not easily be emptied out of the pitcher except by birds ; that in Nepenthes it evaporates, without being renewed, shortly after the elevation of the lid ; that in Dis- chidia and Norantia it is not easy to conceive how the pitchers can be emptied at all ; and, finally, that it is contrary to reason to sup- pose that Providence should make provision for an accumulation of water for the use of animals, exclusively in those places where, in consequence of the humidity of the atmosphere, or the nature of the marshy soil, such an accumulation would be of no use. 124 Proceedings of the It was suggested that pitchers have doubtless different uses in different plants. In the Dischidias it is probable, as Dr. Wallich has remarked, that they are reservoirs of nutriment, from which the roots, emitted by the stem, and constantly found ramifying within them, absorb food for the general support of the individual, and that in this case they become necessary in consequence of their long slender twining stem being too narrow a channel of supply from the subterranean roots to the leaves. With regard to Nepenthes, the following idea of the uses of its pitcher was offered for consideration. It has been discovered by Mr. Valentine, that a vast quantity of spiral vessels is found in the stem and petioles, a quantity so con- siderable that no plant has yet been noticed in which they are equally abundant; now it has been ascertained by Bischoff, that spiral vessels convey air containing about twenty-eight per cent, of oxygen ; and as it is well known that an accumulation of, or an excessive supply of, oxygen is destructive to vegetable life, is it not possible that the pitchers are a contrivance to enable the plant to get rid of its oxygen, and may not the water that they contain have been discharged by the spiral vessels themselves ? It was submitted that a confirmation of this opinion was apparently afforded by an observation of the late Dr. Jack, that the bottom of the pitchers of the Penang species, in the inside, is beautifully punctured, as if by the mouths of vessels ; and also by a remark of Dr. Graham, that the water in the pitchers formed in the Botanic Garden, Edinburgh, was at first subacid, and continued to increase in acidity till the whole evaporated. It was stated that scarcely anything was, however, known of the exact nature of the water in pitchers ; it having been only analyzed in one instance, when Dr. Turner found the contents of Nepenthes to contain minute crystals of superoxalate of potash. It is well known that in Sarracenia the water is putrid ; and in Norantia it is de- scribed as sweet in one species, and bitter in another. The last subject of inquiry was the nature of the pitchers, and their analogy to the other and more common organs of vegetation. With reference to this point, some remarks were made upon the doctrines of morphology, a subject first distinctly adverted to in this country, incidentally and in a very concise manner, by Mr. Brown, in 1816, but originally conceived by Jungius in 1678, and subsequently explained in an admirable treatise by the celebrated poet Goethe in 1790. The sum of this doctrine is, that a plant usually consists of only two essentially different parts, viz., the axis (or stem and root) and the appendages of the axis, all of which, under whatever form they may appear, whether of bracteae, calyx, corolla, stamens, or fruit, are mere modifications of leaves. Consequently, it should follow that pitchers are also leaves ; an opinion that was supported in Sarracenia by a reference to their evident transition from the form of leaf in Dioneea Muscipula, the pitcher itself being a petiole in a particular state, and the lid the lamina ; in Nepenthes and Royal Institution of Great Britain. 125 Cephalotus by their obvious identity of nature with Sarracenia ; in Dischidia by their position upon the stem, by the condition of their petiole, and by their relation to the inflorescence being the same as that of leaves ; and in Norantia by their position with regard to the flowers, and their gradual transition from leaves to their most per- fect state. May 13th. — Mr. Brockedon on the Passage of the Alps by Han- nibal.— Mr. Brockedon, in offering his remarks upon the passage of Hannibal across the Alps, illustrated his observations by draw- ings and maps. His object was to show the errors and absurdities into which writers upon this subject had fallen by fire-side conjectures and re- liance upon previous authors, who were as ignorant of the Alps as themselves, and whose chief authorities were incorrect maps. His own actual examination of above forty of the passes across the Alps, having traversed them nearly sixty times, has brought to test the impossible and impracticable routes laid down by different authors — impossible under the authority of Polybius — which, contemporary as he was with the event, and consistent as he was with himself throughout his narrative, Mr. Brockedon thought was the only authority to be relied upon. He successively exposed the fallacies of Livy, St. Simon, Folard, Fortia d' Urban, Whittaker, Laranza, and other authors who theorized upon any other pass than that of the Little St. Bernard, where alone, throughout the great chain, Mr. Brockedon observed the coincidences of times, distances, and events, as related by Polybius, could be found to have occurred. The researches of General Robert Melville, given to the world by M. de Luc of Geneva, were the first to excite attention to the true line of the passage of the Carthaginians ; the subsequent exa- minations of this and other routes in the Alps by Messrs. Wickham and Cramer, of Oxford, confirmed General Melville's views ; and Mr. Brockedon's repeated journeys over the Little St. Bernard, and every other course across the Alps, which it was possible for Han- nibal with his army to have taken, confirmed his belief in the moral certainty that it was by this pass only that the extraordinary entry of the Carthaginians into Italy was effected. May 20th. — On this evening Mr. Charles John Robertson, of Worton-house, tsleworth, gave an account of his improved method of painting in water colours. The object which the lecturer proposed to himself in the experi- ments which led to these improvements, was the uniting the advan- tages supposed to exist separately and exclusively in oil or in water colours. Oil painting has been supposed to possess greater dura- bility, and the exclusive power of executing pictures upon a grand scale : the oil which is used as a vehicle bringing out the colours to their fullest tone, and producing a richness and mellowness of effect 126 Proceedings of the of which it has been supposed water colours are incapable, which were considered, till within these few years, to be fit for little else than the slight sketchy works of amateurs ; and, indeed, notwith- standing the great and rapid improvements made within the last thirty years, and the beautiful specimens that have been seen in the annual exhibitions of the Society of Painters in water colours, the works painted in water have hardly yet established their just claim to be called paintings, being usually named drawings, to distinguish them from works in oil. Still, every lover of art has felt and appre- ciated the superior brilliancy and purity of the tints of water-colour pictures. This they owe to their being painted with transparent colours on a white ground, where the rays of light passing through the diaphanous colours to the paper, are reflected back to the spec- tator, producing a similar effect to the light reflected through a jewel from the foil at the back ; while pictures in oil, being painted for the most part with opaque colours, give back the light from the surface, and deprive them of that fulness of tint which is possessed by water colours, in this case resembling the light re- flected from the surface of a jewel which, in those of the deepest colour, appears nearly colourless. Now the question of durability is not so easily disposed of as a hasty adopted prejudice would assert. If any collection of oil pictures be carefully examined, those in the highest state of preservation will be found to have suffered considerably, while the majority are obscured from various causes ; the oil itself becomes dark and opaque by time, and acts chemically upon many of the colours ; which again being mixed upon the pain- ter's pallet without regard to their chemical nature, also act upon each other : thus the light colours become browner, "and the deeper colours mealy ; then follows the ruinous practice of cleaning arid varnishing, the evils of which our space will not allow us to enume- rate, but which are well known to those interested in the subject. On the other hand, pictures in water-colours, by the usual modes, require a glass to preserve them from the injuries of dirt and mois- ture, and if they become stained or dirty, cannot be cleanedfwithout the greatest risk of destruction. The risk of breaking, the weight, and the expense of plate glass, would necessarily limit the size, did not the inferior force of water- colours, by the old method, preclude the attempting a large picture. But our limits warn us that we must proceed to describe briefly the new method as proposed by Mr. Robertson, which he illustrated by pictures, one of them containing about forty square feet of sur- face, with whole-length figures the size of life, the production of which excited the full approbation of the audience. Mr. Robert- son attaches the paper upon which he paints, by means of glue and paste, to a strong linen, the back of which he defends by tin foil, also firmly attached by the same means^whichjsecures that part from the effects of damp, a great source of injury to pictures. Beginning with a neutral tint, he washes in all his colours sepa- Royal Institution of Great Britain. 127 rately and unmixed, each separate colour being firmly fixed in the paper, by washing it plentifully with water till the water runs off clear, so that there is no danger of one colour tarnishing another by mixing with it ; by this means the colours are so pure that he is not under the necessity of using those that are not permanent, for the sake of their brilliancy, as it is well known that a transparent colour used over another produces a much brighter third colour than when the same two colours are mingled (his colours are prepared in the usual way). When he has got his picture to the utmost degree of force that he is able by these processes, he varnishes it over in the early stages with a solution of gum tragacanth, and in the latter with a solution of isinglass in alcohol, painting over these and again varnishing, till he produces a depth of colour equal to the most powerful oil picture. By these means colours that, although per- manent in themselves, may injure other colours (permanent sepa- rately) by their chemical agency, become protected from each other, and all are defended from the action of gases and vapours, as well as from injury by smoke, grease, or dirt; for the latter may, with the greatest facility, be removed by spirit of wine, which readily dissolves them, while it cannot injure, even in the slightest degree, the surface of the picture : for since isinglass can only be dissolved in spirit of wine, by being kept at the boiling point for several hours, it is evi- dent that when used in a cold state it cannot affect the varnish. To defend the picture from injury by humidity, it may be varnished by any of the varnishes used for oil pictures, which may all be taken off again readily by alcohol, down to the exact surface of the picture. Nay, if the whole surface were painted over with oil paint and suf- fered to dry, it might be as easily cleaned. Amongst those present were the president and several members of the Royal Academy, who expressed the greatest interest in Mr. Robertson's principles and details. May 27th. — Mr. Brittori's remarks cm, and illustrations of, the Old Domestic Architecture of England. — This subject was illus- trated by a variety of curious prints, drawings, and models, tracing the progress of the art, from the Norman style still extant in some of our ancient buildings, down to the period when Roman architec- ture began to be mingled with our national works, and till it ulti- mately supplanted them in the buildings destined for domestic use, as well as those intended for divine worship. The new buildings at Windsor Castle, and those in and about London, were very particu- larly dwelt upon, as indications of the present state of domestic architecture. Numerous presents were placed on the library table, given by G. Bennet, Esq. They were principally from the South-Sea Islands. 128 Proceedings of the June 3d. — Mr. Ritchie on the relation between Electricity a netism, and on Electricity as the probable origin of all the phenomena of Natural and Artificial Magnetism. — After a few general observa- tions on the nature and laws of action of voltaic electricity, Mr. Ritchie proceeded to illustrate the striking relations between a conductor of voltaic electricity and artificial magnets. As the law according to which the needle, places itself across a conductor is easily forgotten, the lecturer recommended the following artificial mode of viewing it, as the best for fixing it securely in the memory. Regarding the sun as the visible cause of terrestrial magnetism, and conceiving a current moving round the earth in the direction of the sun's appa- rent motion, from east to west, let a person conceive himself looking towards the east, and then lying down on his back, with his feet to the east, he may consider himself as a portion of a conductor, the current of positive electricity entering at his feet and passing out at his head. If he now conceive a magnetic needle suspended above his chest, the north pole of this needle will arrange itself towards his left hand, which will always be its direction, whether he thinks of terrestrial or artificial electricity. Mr. Ritchie then described the mutual action of two voltaic con- ductors, discovered by M. Ampere. If a voltaic conductor act on a magnetic needle, it may follow that two conductors will act on each other, and the manner in which they will act may be imagined by reasoning a priori. If an indefinite number of very short magnets be placed transversely on a flat piece of wood, with their poles of the same name, all placed in the same direction, we shall have, says Mr. Ritchie, something very like the section of a conducting wire. s Let AB be a slip of wood, having a great number of small magnets made of portions of sewing needles, cemented on the slip of wood, with all their south poles above and their north poles below, and let a small magnetic needle be suspended above this compound bar, and the needle will obviously arrange itself as in the annexed figure. If two such bars be placed parallel to each other, as in the annexed cut, with their poles in the same direction, and if one of them be moveable, it will move parallel to itself, till it come in contact with i i i i I i I I I I I Royal Institution of Great Britain. 129 • the other. This is obvious, since dissimilar poles are opposite to each other, attraction must take place. If they be placed, as in the second case, the moveable one will be repelled, and continue to move parallel to itself, till it get without the sensible repulsive action of the other. Viewing these compound bars as metallic slips conducting voltaic electricity, it is obvious that attraction will take place when the cur- rents move in the same direction, and repulsion when they move in opposite directions. The same illustration will apply to a terminated current moveable about one of its extremities, when acted on by a straight indefinite current. Let AB be an indefinite straight conductor, and DC a terminated conductor moveable about the point C. It is obvious that in this position repulsion will take place, and the moveable con- ductor will turn round C, till it arrive at a position at right angles to the straight conductor. At this point the attraction of the other half of the straight conductor will act till it be brought to a parallel position. By viewing the tendency to move in every position, we clearly see that the terminated conductor has a tendency to revolve about the point C, and by a sufficiently powerful battery this revolu- tion may be made to take place. ahn 9t, ~~ **- A I I I I I I I I I I I I I I B 0? £ By substituting a magnet for the conductor the same thing takes place, as in the beautiful experiments of Mr. Faraday and M. Am- pere. A portion of a circular conductor may be viewed as a straight one, and all the phenomena of terrestrial magnetism may thus be satisfactorily explained, by supposing currents of electricity circu- lating about the earth from east to west. Such currents may be made to act on terminated currents, and produce all the phenomena of attraction, repulsion, and rotatory motion, as has been done by M. Ampere. By means of an artificial globe, surrounded with coils of copper wire, Mr. Barlow has exhibited all the effects of terrestrial magnet- ism, on the direction and dip of the needle. Without entering into the scientific details of the theory of terrestrial magnetism, Mr. Ritchie showed, by a very simple experiment, that the old theory, which viewed the earth as a huge magnet having two poles and a middle line, was inconsistent with known facts. If a vessel of water be placed on the middle of a large magnet, and a light magnetic needle floated on the surface of the water, this needle will arrange itself in the direction of the poles of the magnet. So far it agrees VOL. II. AUG. 1831. K 130 Proceedings of the with what actually takes place on the surface of the earth. But the needle cannot be made to remain in that position. The attraction of one of the poles always overcomes the attraction of the other, and the needle floats towards the nearest pole — a fact quite contrary to what takes place when the earth acts on the same floating needle. But it may be asked, how are these currents generated ? Are they voltaic or thermo-electric ? From the constitution of our globe, we can scarcely doubt that they belong to the latter class. The earth abounds with metalliferous veins, and these veins are undoubtedly of different temperatures, and, consequently, thermo-electric effects must take place. The rapid change in the direction of the magnetic equator, when approaching South America, renders this supposition highly probable. The effect of voltaic electricity in forming temporary magnets was exhibited; but as that was fully described in the last Number of our Journal, we refer to it for further information. Mr. Ritchie re- marked, in concluding, that we were fast approaching to the period when all the phenomena of heat, light, electricity, &c., would pro- bably be referred to the same great cause, merely acting in different ways ; and concluded by quoting the following prediction of the late Professor Playfair, which we shall give in his own words : — 4 If, on the other hand, we consider how many different laws seem to regulate the other phenomena of the material world, as in the action of impulse, cohesion, elasticity, chemical affinity, light, mag- netism, galvanism, electricity, the existence of a principle more general than any of these, and connecting all of them with that of gravitation, appears highly probable. * The discovery of this great principle may be an honour re- served for a future age, and science may again have to record names which are to stand on the same levels with those of Newton and La Place. About such ultimate attainments it were unwise to be sanguine and unphilosophical to despair.' June Wth. — Mr. Faraday on the Arrangements assumed by par- ticles on the surfaces of vibrating Elastic Bodies. — This was the subject of a paper read before the Royal Society a few weeks ago, of which Mr. Faraday was the author. He stated, that his principal reasons for bringing it forward on the present occasion arose from a desire to illustrate the characteristic differences between the Royal Society and the Royal Institution, in their modes of putting forth scientific truths ; and his conviction that every thing, whether small or great, originating in the latter establishment, should be placed, as soon as possible, in the possession of the members at large. When a plate or pane of glass is held horizontally by a pair of tongs griping the glass at the centre, and a violin- bow drawn over the edge of the glass, it is made to vibrate ; and sand having been pre- viously sprinkled upon the surface of the plate, the particles arrange themselves into regular forms, figuring forth the quiescent parts of Royal Institution of Great Britain. 131 the glass. These are called by Mr. Chladni, their discoverer, nodal lines. "When light particles, such as scrapings from the hairs of the bow used, dust, or the powder of lycopodium, happen to be on the plate ; instead of proceeding to the same quiescent lines as the sand, they accumulate at the parts in most violent agitation, form- ing a cloud, and at last settling down into little hemispherical heaps, having a peculiar revolving or involving motion. This determina- tion of light powders has always embarrassed philosophers : and M. Savart has founded a theory of some peculiar modes of vibration upon it. Mr. Faraday's object was to show, that the effect is a very simple arid natural one, — consisting of nothing more than cur- rents formed in the air surrounding the plate, which, proceeding from the quiescent to the most agitated parts of the plate, then pass upwards, and in their course carry the light particles with them. Mr. Faraday explained, and demonstrated by numerous experi- ments, how such a current would necessarily result from the manner in which the mechanical forces of the plate are transmitted to the air. He showed that this current could be interrupted by walls of card, when the light particles took new courses. He stated that the heavy particles went to the lines of rest because the air had not force enough to carry them in its course ; but that light particles, being governable by it, were taken in the opposite direction. He confirmed this view by substituting water for air, making the plate vibrate in the former fluid, and showing that the sand was then, carried from the quiescent to the agitated parts, exactly as the lighter particles were in air ; and further, on vibrating plates in vacuo, he found that even the lightest particles went to the lines of rest, because there was no current of air of sufficient force to sweep them in the opposite direction. Want of time prevented Mr. Fara- day from entering upon the explanation of the involving heaps : but this point is fully treated of in his paper read before the Royal Society. He announced that further consideration of the subject induced him to believe he should be able to account, by the same principles, combined with the cohesive power of fluids, for the pecu- liar and hitherto unexplained crispations which occur on water and other fluids lying upon a vibrating plate. This being the last evening-meeting of the season, Mr. Faraday, on the part of the committee, took leave of the members, after earnestly exhorting them to use both individual and conjoined exer- tions to aid the prosperity of future seasons.. In the library was placed a beautiful portrait of Sir Humphry Davy, of the full size, copied by W. Pickersgill, jun., from the portrait by Sir Thomas Lawrence. 132 Proceedings of the Royal Institution. On the 2d of May the usual election took place, when the follow- ing officers were elected : — President. His Grace the Duke of Somerset. Treasurer. Sir George Ducket, Bart. Secretary. Edmund R. Daniell, Esq. Managers. Visitors. Benjamin Bond Cabbell, Esq. Thomas T. Bernard, Esq. Captain Chapman, R.A. Sir Gilbert Blane, Bart. Davies Gilbert, Esq. Robert G. Clarke, Esq. Sir Henry Halford, Bart. Rt. Hon. Reginald P. Carew. Henry Hallam, Esq. John F. Daniell, Esq. Edmund Halswell, Esq. John Fuller, Esq. William Hamilton, Esq. Dr. A. B. Granville. Marquis of Lansdowne. Henry G. Knight, Esq. Geo. Moore, Esq. Lieut-Col. W. M. Leake. Dr. Whitlock Nicholl. Viscount Palmerston. W. H. Pepys, Esq. Lord Seymour. Charles Pilgrim, Esq. R. H. Solly, Esq. William Pole, Esq. William Sotheby, Esq. Hon. W. F. Spencer Ponsonby. Sir J. T. Stanley, Bart. Lord John Russell. N. A. Vigors, Esq. From the Annual Report presented by the Visitors at the same time, it would appear that the property of the Institution is con- sidered at present, when estimated in the lowest manner, as fol- lows : — £. s. d. House and Buildings 14,500 0 0 Library 7,095 7 0 Mechanical Apparatus 787 14 0 Mineral Collection 400 0 0 Laboratory Apparatus 140 0 0 £22,923 1 0 Funded Property. In 3 per cent. Consols, Mr. Fuller's donation . . 1250 0 0 The Sinking Fund 770 15 6 Investment on Laboratory Account 977 411 £2998 0 5 The bond debts and simple contract debts amounted all together to £2352. 6s. 8d. There have been fifty-seven new members elected during the year. ( 133 ) Proceedings of the Royal Academy of Sciences of Paris. BOTANY. Sterility of Hybrid Plants. —On the 9th of May, M. Dutrochet addressed a letter to the Academy, in which he attributes the steri- lity of hybrid plants to the imperfection of their sexual organs. In the flowers of some species of cherry-trees (those derived from the union of the prunus cercesus and the prunus aviuni), the stamina have no pollen ; their antherae form a compact mass which does not divide into pollenic or fertile dust, as is the case with fruitful cherry- trees. Irregularity of the Organs of Vegetables. — On the 6th of June. M. Dutrochet communicated some observations on this subject, which he considers as presenting a phenomenon similar to that which he has observed in some animals, viz. an invariable abortion of some of the parts, so that these plants are in fact consistent or perpetually recurring monstrosities. In an Alpine cytisus, which was terminal, M. Dutrochet observed six petals, four disposed in a cruciform manner, and above them two contiguous petals placed alternately. The manner in which these last were placed prove that there must have been two others which have become abortions, so that the papilionaceous flowers were originally regular flowers, hav- ing eight petals disposed in two ranges alternately. Three of these petals constantly become abortions, and the five remaining ones form the standard, the two wings and the two pieces of the keel. Irre- gular flowers are always lateral; when by chance they become ter- minal, they resume their original regularity, because they have then equal room for developement on every side. Abortions and Irregularities of Flowers. — On the 13th of May, M. Adriende Jussieuread a memoir on this subject, in which he entered into a very detailed examination of the structure of flowers, parti- cularly of the family Malpighia. The flowers of this family have been generally described as regular, or, if authors have pointed out some irregularities, they have cited them as exceptions, whereas they are constant and numerous. In fact, the segments of their calyx are similar in very few cases, their petals scarcely ever ; their stamina differ both in number and in form and dimension, and the number of the ovaries is never in proper proportion to the other parts of the flower. M. Jussieu's object is to account for and systematize these irregularities. A complete flower presents several orders of organs disposed in an equivalent number of concentric circles ; in the dicotyledones (to which this memoir principally relates) the number of parts springing from the same circle is generally five, or a multiple of five; these 134 Proceedings of the parts sometimes rise to the same height, in which case they form a verticilli^ and sometimes to different heights. Although the latter case is much more frequent than the former, the authors who have written on the subject generally speak of these flowers as composed as verticilli, probably because the difference of height between the various parts of each system is so small as to appear to them unworthy of notice. But M. Jussieu, by taking a minute account of these differences, seeks to establish that the most general law rela- tive to the disposition of the leaves of a branch may be equally ap- plied to the parts of the flower. Let us suppose the parts inserted in different points of a spiral line turning on the conic spindle (noyau) of the flower. Let us divide the surface of the cone into five equal parts, by so many lines let fall from the summit to the base, by which each spiral turn will be cut by these lines at five points. Let us then suppose an insertion at any of the points of in- tersection, and place them upon these points alternately (de deux) : after two spiral turns we shall find the sixth insertion situated directly over the first, and the first five will form what Bonnet calls a quincunx. When the parts are large enough for the borders or edges to pass each other, they will cover or lap over each other in such a manner as to form two exterior, two interior, and one inter- mediary, that is to say, covering on one side and covered on the other. The two exteriors will be placed first and second, the intermediary third, and the two interiors fourth and fifth. It is necessary to re- member these characteristics, because they serve to point out the order of insertion where the difference of height is too small to serve as a guide. When the parts are large enough to lap over each other, not only with their borders or edges, but by the greater part of their surface, one will envelope, or lap over, two, two over three, three over four, and four over five. This is the inflorescence which has been called enveloping, and which differs from the quin- cuncial only by the enlargement of the parts. The parts of a quin- cunx in the flower are generally placed alternately with those of the two quincunces which are immediately above and below it. It is difficult to account for this disposition on the hypothesis of a single spiral, but it is perfectly intelligible if we admit the existence of a second spiral entirely similar to the first, and revolving on the same cone, but commencing from the opposite point of the base like the worms of a double screw. It is upon these two spirals that the concentric spirals are inserted alternately. This supposition is justified by observing the flowers on which the parts which are mul- tiples of five, or some other number, alternate among themselves in various rows ; it is evident that this alternation results from the parts being inserted at equal intervals upon several spiral parallels. The petals of the cactus, the stamina and fruits of several of the magno- lias and ranunculi, furnish examples of this. The disposition of the scales in the common pine cone is also an illustration, if not a posi- tive proof, of this. Royal Academy of Sciences of Paris. 135 From what has been said, the five folioli of the calyx of a flower may be considered as placed on the first spiral. At the point cor- responding to that of the sixth insertion, but on the second spiral, the quincunx of the petals will commence, which will also be disposed upon two spiral turns, nearer to the summit than those which bear the folioli. When the system of the petals is finished, that of the stamina will begin, and form a third quincunx, situated on the same spiral as that of folioli, but on the fifth and sixth turns. Lastly comes the quincunx of the ovaries, which will be inserted on the seventh and eighth turns of the second spiral. It has here been sup- posed that each spiral begins to form the first part of one quincunx at the moment at which the other spiral completes another ; but this regularity does not always occur. Thus the second, instead of bear- ing the first petal at the point corresponding with that which a sixth foliolus would occupy, may bear it at the point corresponding with the seventh, eighth, ninth, or tenth ; whence there are four other combi- nations possible ; and although the alteration of the parts in the two successive quincunces, and the corresponding opposition of those of every other quincunx, is apparently unaltered, the regularity is less perfect, because, although a stamen will always be found correspond- ing to a foliolus of the calyx, and an ovary to a petal, it will not cor- respond with the foliolus and petal bearing the same number. The nearer the spiral rises towards the summit of the cone, the more its turns contract and approach each other. The lower, therefore, a quincunx is situated in a flower, the more its parts are separated from each other. This remark may give rise to several deductions. In the first place the principles just laid down will be the less easily recognised in proportion as their exemplification is sought for in a higher or more interior quincunx, because the contraction of the spiral turns tends to give it the appearance of a verticillus, and the slightest deviation in the insertion of a part will tend to change its apparent order: it is therefore in the calyx that these principles may most frequently be verified. The inequality of height in the inser- tion of the petals can rarely be observed, except by their situation being a little more exterior and interior, and even this can rarely be perceived in the flower when open; in the bud it is more per- ceptible. The laws of the quincunx, being once admitted for the calyx and corolla, should also by analogy be admitted for the stamina and the ovaries, although the latter more generally present the appearance of a perfect verticillus. Several instances, how- ever, may be found in which this appearance does not exist ; added to which the developement of the parts of each of these pretended verticilli is much less contemporaneous than is generally supposed. This developement, indeed, would naturally be slower in the highest parts, which must be impeded by want of space ; whence it arises that total or partial abortions are more frequent in proportion as the quincunx is in a more elevated situation in the flower. Thus abor- tions are rare in the calyx, less so in the corolla, still less so in the 136 Proceedings of the stamina, and frequent in the ovaries, the number of which is often less than that of the other parts, and the unequal developement of which may be constantly observed both during and after its progress towards maturity. Thus the passage from regularity to irregularity in. flowers becomes insensibly established. These irregularities could hardly be explained on the supposition of the parts being exact ver- ticilli, and therefore placed in conditions equally favourable to developement. In fact, no examples of irregularity are found in flowers of the valvulary or twisted efflorescence, which invariably indicates the disposition of the parts in verticilli. In a quin- cunx, on the contrary, it is clear that the upper parts are placed in a situation more unfavourable to their developement. This is espe- cially true with respect to the ovaries, because the action resulting from the relative situation of the parts has fuller force from there being no quincunx above it. This tendency to irregularity in the flowers in which the parts are disposed in quincurices, is not much observed when the two halves of the conic spindle are placed in equally favourable conditions, which is the case when the axis of this cone has a direction according to the elongation of the peduncle. But when the flower rests on the peduncle by an oblique base, one of its halves is situated higher than the other with relation to the axis of the plant, and is therefore in a situation more likely to produce abortions. This obliquity of the base exists in the majority of irre- gular flowers, particularly in those in which the inequality of the two halves is very decided, and which are called didynamia. These causes of irregularity will be much greater, if, instead of supposing the spiral constructed on the circle which forms the base of the conic spindle, we suppose it constructed on a section which is oblique to the axis, that is to say, on an ellipsis. In this case, every spiral turn ascending and descending alternately as respects the axis, the series of the insertions will no longer have an exact reference to their heights, and thence will result an order apparently differing from the quincunx. The calyx of the antirrhinum majits, the insertion of which is extremely oblique, affords an example of this. M. Jussieu, having thus laid down his position, proceeds to exemplify it by nu- merous examples, illustrated by plates ; but it is unnecessary to cite them here, as the above explanation of his theory will be sufficient to enable our botanical readers to verify or refute his ingenious hypo- thesis. We shall take care to make known the report which will be made to the Academy on the subject. CHEMISTRY. Perchloric Acid — Per chlorates — a test for Potassa and Soda. — On the 25th of April, M. Serullas communicated the particulars of some experiments which he had recently made on this acid, con- sidered as a re-agent, by means of which to distinguish and separate soda from potash, either alone or combined with other acids. He led to make these experiments from observing the great differ- Royal Academy of Sciences of Paris. 137 ence in the degree in which the perchlorate of potash and the perchlorate of soda are soluble. The first, at a temperature of 15° C. (59° F.), requires more than sixty times its weight of water to dissolve it, while the latter is remarkably deliquescent, and consequently easily soluble, not only in water, but even in alcohol. In order, therefore, to distinguish and separate these two alkalies, it occurred to M. Serullas that it would be expedient to ascertain the possibility of producing, in the same liquid, a salt from potash, which would be almost insoluble, and one from soda which would be very soluble. Neither hydrochlorate of platina, tartaric acid, nor hydrofluosilicic acid, all of which may be em- ployed to precipitate potash and soda, afforded sufficiently accurate means of obtaining the desired result ; but M. Serullas ascertained that if perchloric acid be poured, drop by drop, into a solution of soda and potash mixed, a perchlorate of potash is instantly precipi- tated ; the perchlorate of soda (or the soda itself, if there be not an excess of acid) remains in the liquid, whence it may be separated by concentrated alcohol, which will precipitate at the same time the small quantity of perchlorate of potash which may remain. A solution of perchlorate of soda, to which potash is carefully added, will instantly precipitate a perchlorate of potash, the soda becomes free, and may be separated by alcohol. Owing to this great differ- ence between the solubility of the perchlorate of potash and that of every other salt having the same base, it is easy to ascertain the ex- istence of potash, either free or combined with other acids, in any saline solution, as the smallest quantity of perchloric acid occasions a precipitation of perchlorate of potash, while the other acids are rendered free, and may be isolated by alcohol. This experiment has been tried with the sulphate, nitrate, chlorate, bromate, mu- riate, and hydrobromate of potash. By this mode of proceeding the simultaneous existence of soda and potash may always be ascer- tained, and it will also be easy to examine the nature of the acid primitively combined with the former, as it may always be isolated by concentrated alcohol. There will also be a great advantage in employing Jthe perchlorate of barytes, and that of silver, (both of which are very soluble,) in cases of combinations of soda and potash with sulphuric acid or hydrochloric acid, as, in both cases, by means of alcohol, all the perchlorate of soda may be obtained on the one hand, and on the other, all the perchlorate of potash, with the sulphate of barytes, or the chlorure of silver, from which the perchlorate of potash may easily be removed by washing it in warm water. The general results of the above experiments are — 1. That perchloric acid forms, with potash, a salt soluble with great difficulty, and requiring for its solution sixty times its own weight of water, at a temperature of 59° F. 2. That soda forms, with the same acid, a salt very deliquescent, and consequently easily soluble, either in water or even in the most highly concentrated alcohol. Tins fact was previously unknown, j 138 Proceedings of the 3. That these opposite qualities of the two compositions afford the means of separating soda and potash when in solution together; the former generating a perchlorate easily soluble in alcohol, and the latter a perchlorate absolutely insoluble in that liquid. 4. That any acid whatever, which was primitively combined with potash, will always be separated and set at liberty by perchloric acid. Production of Perchlorate from Chlorate of Potassa. — On the 23d of May, M. Serullas communicated the result of his obser- vations on the change of chlorate of potash into oxychlorate (per- chlorate) of the same base, by the action of heat, and on a new method of obtaining oxychloric or perchloric acid. The simila- rity of the phenomena manifested in the production of oxychlo- rate of potash, with those observed in the production of oxychloric acid, led M. Serullas to suppose that the simple action of a high temperature, maintained within certain limits, would convert chlorate into oxychlorate of potash, by combining part of the oxygen with the chlorate remaining undecomposed. He had long since observed that chlorate of potash, decomposed by fire, left a saline residue not easily soluble, and removable with difficulty from the tubes in which the experiment was made, but he concluded that former che- mists, in establishing that this residue consisted only of chlorure, had taken notice of all the effects produced by heat at different periods of the operation ; and, therefore, had not directed his attention to that point until accidentally led to do so in the course of his experiments on oxychloric acid. He observed that when chlorate of potash is heated in a crucible, it first melts, and then boils, at which state there is an escape of oxygen. When the heat is regulated sparingly, after a certain duration of the ebullition, this escape of oxygen ceases, unless the temperature be raised ; if the operation be then suspended, and the solution be filtered while hot, a consi- derable quantity of oxychlorate will be obtained, when it cools, in small brilliant crystals : 40 parts of chlorate furnished 17'5 parts of oxychlorate. M. Serullas has established that Stadion, and all the other chemists, were wrong in supposing that oxychlorate of potash is decomposed at 392° Fahr. : it requires at least 752° Fahr. In order to obtain oxychloric acid, oxychlorate of potash must be boiled with silicated hydrofluoric acid, in great part eva- porated, so as to obtain, when cool, a more abundant deposit of the gelatinous fluosilicate of potash ; this must be filtered, again evaporated, left to cool, again filtered, concentrated in a cap- sule, and then distilled in a small retort. In order to precipitate the small quantity of fluosilicate of potash and of oxychlorate, which may exist in the oxychloric acid, it is only necessary to pour into it a little concentrated alcohol, filter it, dilute it with water, and then let it evaporate. The oxychlorate of potash contains 65-725 parts in 100 of oxychloric acid. This simple means of pro- curing the acid is highly important, as from M. Serullas' discovery Royal Academy of Sciences of Paris. 139 of its utility in separating soda from potash, as above-mentioned, it will necessarily become in great request. Action of Vegetable Substances, Gum, Sugar, fyc. in contact with Metallic Oxides. — On the 2d May, M. Becquerel communicated to the Academy a very interesting paper on carbonate of lime in crys- tals, and on the simultaneous action of saccharine and mucilaginous matters upon the oxides of certain metals, obtained through the me- dium of alkalies and earths. M. Becquerel has, for a considerable period, directed his attention to the means of submitting organic substances to the action of electric currents, with the view of ascer- taining the causes of some of the phenomena observable in those substances, particularly that of fermentation. It was already known, from the experiments of Cruikshank and Daniell, that on exposing a solution of sugar and lime in water to the action of the atmosphere, small crystals of carbonated lime are produced on the surface ; but the cause of this phenomenon was entirely unknown, although it was supposed that the carbonic acid might perhaps be supplied by the atmosphere. M. Becquerel, however, has, by means of the following experiment, ascertained the real source of the acid. He plunged into a wide-mouthed bottle, filled with barytes water, two tubes, (the lower parts of which were stopped with moistened barytes,) filled, the one with a solution of lime and sugar, and the other with a solution of sulphate of copper. The liquid contained in the first tube was connected with the positive pole of a voltaic pile, by means of a plate of platina, and that in the second tube with the negative pole, by means of a plate of copper. The moment this communication was established, the sulphate of copper was observed to be decomposed, the copper was precipitated in a metallic state on the copper plate, the sulphuric acid was absorbed by the barytes, and the oxygen was transported to the positive pole ; where, by a re-action on the carbon of the sugar, it produced car- bonic acid, which was immediately combined with the lime. After the lapse of some days, small prismatic crystals of carbonate of lime were observed on the plate of platina, and continued to increase as long as there remained any lime in the solution. Gum, the compo- nent parts of which are nearly similar to those of sugar, produced the same effect. In both cases, those portions of the vegetable sub- stance which do not tend to the production of the carbonic acid, or of the water of crystallization of the carbonate, are converted into acetic acid. M. Becquerel was next led to examine the simultaneous action of saccharine and mucilaginous substances upon the metallic oxides, through the medium of the alkalies and the earths. If hydrate of copper be acted on by water and lime, with the aid of heat, it becomes black, and probably passes into an anhydrous state ; but if a very small quantity of sugar be added, a portion of the oxide is dissolved, and the liquid assumes a beautiful blue tint, similar to that of a solution of oxide of copper in ammoniac. 140 Proceedings of the Honey and sugar of milk have the same properties, which, how- ever, have never been observed, except in saccharine substances. Potash and soda may be substituted for lime in this experiment with a similar effect, except that their faculty of dissolving is greater, whereas that of barytes and strontia is much less. Gum does not produce the same effect as sugar : that substance, when dissolved by water, is not precipitated by the alkalies and earths which we have just mentioned, but if a deutoxide of copper, in a state of hydrate, be added, a flaky insoluble precipitate of gum and oxide of copper is formed. When there exists in the solution a small quantity of saccharine matter in addition, it re-acts immediately on the excess of oxide, and of copper, which has been added, dissolves it, and gives a blue colour to the solution. In order, therefore, to detect the existence of gum and saccharine matter in any substance which contains both, it is sufficient to add potash and caustic lime to the solution, and then apply hydrate of copper to it. The mucilage found in a decoction of linseed pro- duces the same effects as gum; and as the solution becomes slightly tinged with blue, it is evident that it contains saccharine matter. If the solution be acted on by heat, the effects are different. If a solution of sugar, potash, and deutoxide of copper, in water, be heated to the boiling temperature, the blue colour changes succes- sively to green, yellow, orange, and finally to red, and then all the deutoxide is changed into protoxide. If oxide of copper be then added gradually, until there is no longer any protoxide formed, all the sugar is decomposed, and nothing remains in the solution but carbonate of potash and a small quantity of acetate of the same base. The saccharine matter of milk, which, when cold, acts on copper and potash in the same manner as common sugar, acts dif- ferently when heated. The deutoxide of copper passes first to a state of protoxide, and is then reduced to a metallic state. The oxides of gold, silver, and platina, submitted to the same tests as the oxide of copper, are reduced to a metallic state, while the oxides of iron, zinc, and cobalt do not undergo any change. The deutoxide of mercury is reduced to a metallic state by potash and the saccharine matter of milk ; it then, in consequence of the water which is interposed between the parts, presents itself under the form of paste. Under this form, the mercury may be applied to glass without the necessity of using tinfoil ; it is sufficient to spread the paste in a very thin layer, and heat the glass slightly, to remove the water which is interposed. Lime, barytes, and strontia, when acting by means of heat on the deutoxide of copper and saccharine matter, do not form compositions similar to those of the alkalies. Lime, for instance, does not convert the deutoxidp into a protoxide, or a metallic state ; it occasions a precipitate of an orange-yellow colour, formed of the protoxide of copper and lime. In the same manner, proto-cuprates of barytes and strontia are precipitated. These are the principal results of M. Becquerel's experiments, which Royal Academy of Sciences of Paris. 141 have considerable importance, as showing the intimate connection between the electric and chemical systems. Oxides of Barium. — On the 13th June, M. Despretz stated that the hydrate of barytes, which has been generally said to resist heat, is decomposed at a sustained red heat. This fact, which completes the series of experiments tried with lime, magnesia, and strontium, proves that no oxide of barium will retain water at a high tempe- rature. Azote and Iron. — At the same meeting, M. Despretz also stated, that iron, at a red heat, subjected to the action of azote gas, is sen- sibly increased in weight ; it disengages azote when dissolved in the acids. Sulphates. — M. Despretz also remarked, that all the sulphates which are not liable to be decomposed by heat alone, disengage sulphur, when acted on by carbon or hydrogen gas at a strong red heat. GEODESY. Heights of the Pyrenees. — On the 4th April, M. Puissant presented to the Academy a report on a memoir by M. Coraboeuf, entitled * Sur les Ope'rations Ge'odesiques des Pyrenees et sur la Cornparaison du Niveau des deux Mers.' The object of this paper was to fix with certainty the heights of several of the summits of the Pyrenees, and to determine the long-contested question as to whether the waters of the Mediterranean are precisely on the same level as those of the ocean — both being, of course, considered as in a state of perfect tranquillity. The report stated that the mode of operation, adopted by M. Coraboeuf and his associates, was such as almost to preclude the possibility of any important error existing in his conclusions. His trigonometrical observations were always made in the most favourable state of the atmosphere, and the calculations result- ing from them worked with scrupulous fidelity. The results obtained by M. Coraboeuf generally coincide with those mentioned in the * Base du Systeme metrique decimal ' — the greatest difference being Om 24 on a distance of 9514m 78, and that but in one in- stance, the distance from Espira to the southern point of the base of Perpignan. In calculating the heights, M. Coraboeuf made use of two tables, which he has annexed to his memoir — the one being the height above the Mediterranean, as observed by him on the eastern side, and the other the height above the ocean on the western side. The medium between these two calculations has been adopted as the definitive height. The greatest difference found between the two heights is that of Gardan de Montagu, which varies 2m 64 ; but this is to be accounted for by the great difference of the level between 142 Proceedings of the this point, which is situated very low, and the Crabere, the absolute height of which is 2634m ; because, in such a case, the variability of the refraction sensibly affects the zenithal distances employed in the calculation of the differences of the levels. This has induced M. Corabceuf to adopt the summit of the Crabere as the point of com- parison between the levels of the sea and ocean. His admeasure- ments were made by the southern direction of the intersection of the triangle, by the northern ditto, and by the diagonals ; the mean result of these admeasurements gives, for the height of the Cra- bere . . above the Mediterranean . 2633m 50 above the Ocean 2632 77 Difference . . Om 73 Another series of calculations proves that the greatest probable error in the admeasurements is, for the southern, lm 860 ; for the northern, lm 421 ; and, for the diagonals, lm 416; — so that, even if there be any difference in the level of the Mediterranean and the ocean, it must be less than one of the above errors, since, according to the theory, the probability of that extreme error existing is only 150:000. The principal of the absolute heights determined in metres are the following : — ra Bugarach . . . 1230.64 Canigou .... 2785.23 Pic du Col de Liouses . 2831.61 Pic Oriental du Col Rouge 2805.81 Pic d'Appi, St. Barthelemy . 2348.83 Moncal .... 3079.51 Lisserateca 1408.58 m Picd'Ani . . . 2504.25 Orhi .... 2016.63 Pic du Midi de Bigorre . , 2876.74 Troumouse . . . 3086.25 Montespe . . . 1848.56 Maupas . . . 3110.15 In a subsequent part of the memoir, M. Corabceuf has rectified an error of Delambre, who had supposed that there existed a differ- ence of 3 toises in the height of the summit of Salces, as taken at Montjoin and at the marsh of Leucate. The fact is, that the height of the point above the Mediterranean is . . 362.26 toises. and above the Ocean . 361.81 Difference . . 45 Thus affording an additional proof that the two surfaces may be considered as forming one level. This work will form part of the new geometrical description of France; and from its lucid details, minute calculations, and important geodesical researches, was con- sidered by the Academy as deserving of insertion in the ' Recueil des M&noires des Savans Etrangers.' I GEOLOGY. Terrains Tertiaires. — On the 26th March, M. Reboul, a corre- sponding member of the Institute, read a memoir, the object of Royal Academy of Sci ences of Paris. 143 which was to prove that the marine deposits of the Mediterranean basins of the departments of the Herault and the Aude corres- pond, as to their position, with the coarse calcareous (calcaire gros) formation of Paris, and not with the upper marine sands and freestone. In this opinion, which is contrary to that of most geolo- gists, M. Reboul stated that he had been confirmed by a comparison of the fossils in the two basins. The lower marine deposit of the south of France is, like that of the Sejne, covered with the gypseous and siliceous calcaire of fresh water (eau douce), and in both basins an upper, or rather mixed, marine deposit succeeds the fresh water deposit. The essential difference between the lower deposits of the south and those of the Seine is, that the former are free from all mixture of fresh water fossils, and at the same time from concretions of silex, of saline deposits, and even from compact, fine-grained rocks. All these various productions are, on the contrary, found in the upper or mixed earth of this basin, which forms a stra- tum over the fresh-water deposits, or rather which is subordi- nate to them. In the basin of Paris the same productions are found in abundance in the upper stratum, but they are also found, though in a smaller proportion, in the lower stratum. As the fresh water deposits have, in this basin, preceded, or at least been associated, with the first sediments of the calcaire gros, M. Reboul distin- guishes basins of this kind by the name of prolymneens and by that of metalynnieens — those where the fresh water does not appear to have penetrated until after the completion of the deposits of the first epoch ; such are those of the Aude, the Oise, and the Herault. The comparison of the sediments of these two species of basins opens a new field of inquiry for geologists. On the Chalk Formations of the South of France.— On the 25th of April, M. Brogniart read to the Academy a most interesting report on a memoir by M. Dufresnoy, entitled ' Des Caracteres particuliers que presente le terrain de craie dans le Sud de France et sur les pentes des Pyrenees.3 The generality of the world, and even many eminent geologists, have considered that they were fully acquainted with the nature of chalk, from observing in the quarries its immense masses without any distinct stratification, and its beds interrupted by flint stones; but, having confined their attention to the external and mineralogical characters of chalk, and neglected its geological peculiarities, they have yet to learn that strata, which have not the external character of white chalk with black silex, may and do belong to the same period and the same geological formation, because they possess the same peculiarities which, in the de- posits of white chalk, form the true geological characteristics. There are three modes of determining the rank which any deposit occupies in the series of which the shell of the globe is composed. — 1st. The nature of the strata which are constantly found above or below it — this is the geological characteristic ; 2dly, the nature 144 Proceedings of ihe of the rock or stratum itself and the minerals which accompany it — this is the mineralogical characteristic ; and 3d, the organic remains contained in it — this is the zoological or organic characteristic. Of these, the second is the least certain. By chalk deposits, in a geological sense, therefore, we mean not merely those composed of white chalk, but such as occupy the same position in the beds of the globe as chalk usually occupies ; which contain the same species of organic remains ; but which may or may not present the same mineralogical characters. Hence chalk formations (terrains cretaces) may be black and compact, yellow and compact, in masses or in strata, with or without silex, and even wholly composed of sand and freestone, with- out containing any mineralogical chalk, and even scarcely any carbo- nate of lime. Hence it is that it has been hitherto supposed that there were no chalk formatious in the south of France and the Pyrenees. M. Dufresnoy, by his observations, has established three series of facts : — 1st. He has recognized these formations in parts of France and Spain in which their existence was hitherto unknown ; 2dly, he has shown that they contain mineral masses which were supposed wholly foreign to them ; and, 3dly, he has, on the one hand, aug- mented the number of their zoological characteristics, and, on the other, has diminished the negative importance hitherto attached to the absence of certain shells. In the south of France these formations have been recognized as forming a subterranean valley, the northern and southern borders of which show themselves by hillocks or mounds of earth, separated from each other, but tracing, by their disposition, two zones from east to west. The northern xone com- mences in the south of La Vendee, near Rochefort and Royant, and extends to the foot of the maritime Alps. The southern zone rests on the northern declivity of the Pyrenees, commencing from the eastern extremity of the Corbieres, and extending as far as Bayonne in a narrow band. At Bayonne it becomes wider, and, entering Spain, extends to Cardonne. The valley inclosed by these zones is almost entirely filled with terrain tertiaire arid alluvial earths. M. Dufresnoy remarks that, by a general and almost regular elevation of the granite chain of the Pyrenees, chalk formations have been carried to a great height, acquiring a compact texture and a black colour : Mont Perdu, a summit 3500 metres above the level of the sea, belongs to this class of chalk formations. Another elevation, that of the ophites, has also, though in a much smaller degree, deranged the horizontal position of these deposits ; but as the eruptions of ophite, to which this derangement is probably owing, have been much less abundant on the southern than the northern base of the Pyrenean chain, the chalky formations have been much less deranged from their position on the Spanish than on the French side. The proofs which M. Dufresnoy gives of the nature of these formations are quite satisfactory : indeed they have even proved the existence in France of a group of chalk deposits (the Weald group), which had previously been only observed in England. The chalk Royal Academy of Sciences of Paris. 145 deposits of the north of Europe are placed under the terrains tertiaires, and over those known by the name of epiolithic (upper and middle oolite), because they appear to form the upper part of the great oolitic mass of the European Jurassic earth. The parts in the south of France, in which they have appeared covered with the terrains tertiaires, are the Landes, Medoe, the environs of Bordeaux, and St. Paulet, near the Pont St. Esprit: those in which the deposits under the chalk may be referred to the epiolithic group, are much more numerous, chiefly near Rochefort and St. Jean d'Angely. The principal difference of the physical structure of these chalk formations from those of the north of Europe is, that they are generally in oblique strata, which may be partly occasioned by the elevation of the crystalline rocks, which constitute the Pyrenean chain, lifting up part of the layers of chalk in greater or smaller angles. The mineralogical characters of these deposits in the south of France are, in some respects, similar and in others different from those of the north of Europe ; but these differences are of less importance, inasmuch as sedimentary rocks, to which these belong, can never offer those decided and uniform mineralogical characters which distinguish the crystallized rocks : for the latter are formed under the influence of chemical composition, an invariable principle of nature ; whereas the former may almost be said to be mechanically constructed, under circumstances perpetually varying and subjected to no certain rule. The chalk formations of the north, of Europe are composed (commencing from the surface) of white chalk, a grayish and friable rock called tufous chalk, a sandy rock, filled with green particles, and called glauconie crayeuse, and fre- quently of a sandy and ferruginous rock. Under this last rock there has been observed in England, and particularly in Sussex, a remark- able deposit of shells and fossil animals of the lake and river species : this is called the groupe Veldien. Sand, tolerably pure freestone, some metallic combinations of hydroxidated iron, and pyrites, are also observed in these earths. M. Dufresnoy has ascer- tained that the greater part of these substances are found in the chalk deposits of the south of France ; and particularly that the groupe Veldien, supposed to be peculiar to Sussex, exists at the base of the Montague d'Angouleme and at La Grasse. Although this deposit is less distinct in France than in England, it is easily recognized by the argilo-calcareous nature of its rock, by its position, and by its lacustrine shells (melanie, paludinis). The great difference in the mineralogical character of these deposits from those of the north of Europe is the almost total absence of white chalk, which has either never been deposited or else been carried off. The formation generally begins with the tufous chalk. Another very remarkable difference is, that in some cases (particularly at St. Froult, near Rochefort), they con- tain masses of gypsum, with its accompanying sulphur: by the VOL, II. Aua. 1831. L 146 Proceedings of the derangement of the beds, these masses appear to have intro- duced themselves from below, and been developed there. Ma- rine salt is also found in these earths ; and M. Dufresnoy supposes that the famous bed of sea salt at Cardonne in Catalonia ought to be classed among the chalk beds. But it is in the zoological characteristics of these formations of the south of France that M. Dufresnoy has found the most distinct proofs of his theory, and, at the same time, the most remarkable anomalies. M. Dufresnoy, in addition to the belemnites, ammonites, and other fossils peculiar to chalk, has found in these earths the bulla, the cypraea, the melonia — several kinds of the Venus, the Lucina, the crassatella tumida, the neutina perversa, and other fossils, which had hitherto been only found in the terrains tertiaires. This would, at first sight, appear to materially lessen the reliance to be placed on the zoolo- gical characteristics of strata ; but it must be considered that, in judging of the character of a stratum from its zoological character- istics, there are four points to be specially examined. — 1. The minute difference of the species of fossils. 2. The geographical position of the bed : this is important, because it is to be supposed that a difference of latitude produced the same difference in zoological pro- ductions of the ancient as of the modern world. 3. The position of the different species in the strata. 4. The relative number of the species, which are characteristics of the stratum in ques- tion, and of those of which the geognostic position appears an anomaly. In the present case, M. Dufresnoy informs us that the anomalous or littoral fossils (by which we mean those usually found in the terrains tertiaires) are assembled in layers distinct from those which contain the pelagian fossils (as we may call those fossils which are characteristic of chalk), and appear the results of a separate deposit. We might thence be led to suppose that, while a precipi- tate of chalky limestone, enveloping the belemnites, ammonites, and other pelagian fossils, was forming at the bottom of the deep seas, a calcareous earth, enveloping the cerites, the ampullae, and other molluscae which could inhabit shallow waters, was simultaneously forming itself near the shores, and in the shallow waters ; so that the chalk and the terrains tertiaires would, according to this hypothesis, have been formed nearly at the same time, and in the same seas, but at different depths. Thus the fossils similar to, though rarely identical with, those of the terrains tertiaires, would be the littoral fossils of the seas at the epoch of the formation of the chalk. This would throw light on the nature of the chalk of Maestricht, which is so different from all others, and might be supported by the presence, in that bed, of the metosaurus, an animal which, if a marine animal at all, could only have lived near the shores. But the concurring observations of different kinds, establishing that the chalk deposits and the terrains tertiaires belong to two distinct and probably remote epochs, are too numerous to admit of our adopting the above hypothesis. As, however, the co- Royal Academy of Sciences of Paris. 147 existence of the two species of fossils in the chalk formations disco- vered by M. Dufresnoy in the south of France appears to break down the distinct line of separation which exists between the ter- rains tertiaires and the chalk in the north of Europe, we must have recourse to the consideration of the relative number of the two species of fossils, in order to see whether the anomaly and confu- sion are so great as might be feared. The number of species of shells and zoophytes which M. Dufresnoy has distinguished in these strata is 124, of which 110 are determinable as genera. Of these there appear to be only the following five which distinctly belong to the terrains tertiaires, as well as to the chalk strata : — Cardium aviculare, Crassatella tumida, Cerithium diaboli, Nerita perversa, and Tiirbinallia elliptica. There are about ten others, to which M. Dufresnoy has not been able to assign names, but which he con- siders to be identical with some of the species belonging to the ter- rains tertiaires. Thus, at the outside, there are but 15 out of 124 which belong to the two species of deposits ; the 209 others have always been recognised as belonging distinctly to chalk formations. M. Brogniart then proceeds to establish, in an elaborate but lucid line of argument, that a slight anomaly of this kind cannot diminish the weight to be attached to zoological characteristics in determin- ing the nature and epoch of a particular deposit. He remarks that it is certain that every new deposit of earth must have been occasioned by some extraordinary convulsion of nature ; and that all experience shows us that the animals existing at one epoch dif- fered so materially from those existing at another, as to enable us to distinguish, by their organic remains, the relative epochs of the for- mation of each deposit ; but it does not therefore follow that in each of those convulsions of nature the whole of the then existing species of animals were so completely annihilated as to prevent any of them surviving or re-appearing in the succeeding epoch, in which case the admixture of the different species of fossils will be accounted for; only, as in this case, the number of those belonging to a pre- ceding epoch will bear a very inconsiderable proportion to that of those which properly characterise the epoch under examination. In support of his opinion he cites the chalk formation discovered by M. Merton in 1828, in New Jersey and Maryland, which contains fossil remains similar, though not identical, to those of the chalk of Europe, and also several of those which we have called litto- ral, and attributed to the terrains tertiaires. Hence he concludes that the zoological characteristics of strata form the surest guides as to their nature and epoch, although their geognostic and mine- ralogical characteristics may also be taken into consideration as additional evidence. On these grounds, he considers that M. Du- fresnoy has fully proved the existence of the chalk formations in the south of France — a discovery which is not only important as a matter of information on the structure of that part of the globe, but as affording a guide for useful mineralogical researches, founded L 2 148 Proceedings of the on the knowledge we possess of what substances are found beneath chalk, though never either above or in them. The Memoir of M. Dufresnoy was ordered to be inserted in the * Recueil des Memoires des Savans Etrangers.' Soring the Earth. — On the 20th of June a letter was read from M. Jobard, of Brussels, announcing that he had brought to perfec- tion a new machine for boring the earth to any depth, and through any soil. He stated that his plan had been -tried with the greatest success in the neighbourhood of Marienburg, where he had rapidly attained a depth of seventy-five feet, through an inclined rock of phylade, mixed with argillaceous flints. By a process something similar, though less perfect, wells have been dug in China to a depth of from 2000 to 2800 feet, through solid rock. M. Jobard antici- pates the greatest advantages to geognosy from his discovery ; and, with the usual enthusiasm of projectors, looks forward with confi- dence to the period (not far distant) when we shall be as well acquainted with the centre of the earth as we now are with its surface. The Lesser Atlas. — At the same meeting M. Cordier communi- cated some geological observations made by M. Rozet in Africa. M. Rozet is now of opinion that the earths which he had formerly considered as terrains de transition are, in fact, to be classed among those belonging to the epoch of the lias and the calcareous gryphites. The most elevated summit of that part of the lower Atlas visited by M. Rozet, and measured with the assistance of the barometer, was 1399 metres (4590 feet) above the level of the Mediterranean. MEDICAL SCIENCE. Cure of Fever. — On the llth of April, M. Rousseau announced to the Academy, that in three distinct cases of recent occurrence, fever had been completely cured by a few doses, of a drachm each, of the powder of holly-leaves, diluted with half a glass of water. The Academy directed the Medical Committee of the Prix Mon- thyon to take cognizance of the cases. On the 23d of May, M. Deleschamps, a young chemist, announced that he had succeeded in obtaining a new vegetable matter from the bark of holly, to which he had given the name of ilicme, and which may be substituted for quinia in the treatment of intermittent fevers. It will be recollected that an extract of the bark of willow, called salicine, has already been suggested as a substitute for sul- phate of quinia ; should experience prove that the qualities of these two matters are at all comparable to those of quinia, their low price will render the discoveries highly important to the lower classes. Royal Academy of Sciences of Paris. 149 Lithotrity. — On the 18th of April, Dr. Civiale read a memoir on the diseases of the bladder, in which, after arguing on the general advantages of lithotrity, he expressed his opinion that, in cases where that mode of operation is absolutely impracticable, and it therefore becomes necessary to cut into the bladder, the hypogastric operation, as now simplified, is generally preferable to those by the rectum or the perina?um. He detailed at great length the particulars of a. case in which he had successfully operated in that manner on a Russian nobleman, who had been suffering the most intense agony for more than eight years. The irritation and inflammation of the parts were so great as to render lithotrity impossible, and even excision quite a forlorn hope. The operation was, however, per- formed, and the patient perfectly cured in twenty-eight days. From the details of this case he draws the conclusions — that the cysto- tomie sus-pubienne may be performed in cases which at first sight appear most opposed to it ; and that the passage of urine through the wound is no serious obstacle to its cicatrisation. He also takes occasion particularly to advise all medical men to carefully examine, in each case submitted to them, whether the inflammation of the urethra be the result of local irritation of the urethra itself, or sym- pathetic, and arising from the diseased state of the bladder, as in the latter case nothing can be done to relieve it until the primary cause is removed by the abstraction of the stone. At the meeting on the 25th of April, M. Larrey read a report on a memoir sent to the Academy some time since by Dr. Civiale, in which he gave the latter great credit for his perseverance in bringing lithotrity to per- fection, but regretted that his anxiety to support his favourite theory had induced him to record only the favourable cases, and remain silent on those in which the operation had terminated unfavourably. The reporter said that the official reports of the hospitals proved that the number of patients who have died after being operated on by lithotrity is, in proportion, as great as that of those who have not survived the operation of cutting out the stone. At the subsequent meeting, Dr. Civiale questioned the correctness of this report, and repeated, that, in 1 52 cases, lithotrity had been successful. M. Lar- rey's documents were, however, official ; and the real comparative merit of the operations must still be considered as undecided. New Surgical Instrument. — On the 2d of May, Dr. Tilhol pre- sented to the Academy a new intrument for the purpose of making injections into the cavities of the mucous membranes, and abstract- ing the liquid contained in those cavities. Temperature of the Blood. — On the 9th of May, a memoir on this subject, by M. Collard de Montigny, was read to the Academy. It maintains that the temperature varies in the course of circulation, and that (contrary to the received opinion) it is lower when the blood 150 Proceedings of the leaves the left ventricle of the heart than when it enters the right ventricle. M. Collard supposes the proper temperature of the blood to be eight degrees (?), and that the variation depends on physical causes. The novelty of the theory entitles it to mention, but we shall defer any more detailed account of it until after MM. Dulong, Savart and Flourens have made their report upon it. Use of Gold in cases of Syphilis.— On the 16th of May, M. Ma- gendie made a very favourable report on a work by M. Legrand on this subject. The author establishes that gold acts favourably on the digestive organs, without weakenmg the patient, and at the same time produces an exhilaration of spirits. There are four methods in which it may be advantageously administered ; 1st. me- tallic gold reduced to a state of extreme division ; 2d. the oxide of gold with potash ; 3d. the oxide of gold with tin ; 4th. the per- chloride of gold and sodium. Of these the last is by far the most powerful. It is applied by mixing three parts of the perchloride of gold and sodium with nine parts of ^any inert powder, and admi- nistered by way of friction on the tongue, in doses, varying accord- ing to circumstances, from -£§ to J of a grain per day. As much as a grain has been given with safety, but this requires care. This is the least expensive of all the preparations of gold. Next to this in strength is the oxide precipitated by tin, then the oxide precipitated by potash, and, lastly, the gold in a state of division, which is the mildest, and, at the same time, the surest form under which it is administered. It is obtained by dissolving one part of perchloride of gold in fifteen parts of distilled water, and then pouring into it little by little a solution of four parts of proto-sulphate of iron, in sixteen parts of distilled water, until there is no longer any precipitate produced. The precipitates are then collected and preserved for use. This is administered by friction on the tongue, in doses from one quarter of a grain to four grains per day. It may also be administered internally in a spoonful of conserve of any kind. The oxides are employed in the same manner, but in doses of -jJjy of a grain to one and a half or two grains per day. They are more frequently given internally, either in pills of six grains of oxide, with sixty grains of extract of mezereon, or any other extract of a milder character, divided into sixty pills, of which from one to ten are taken fasting in a gradually increasing ratio, or in lozenges made of six grains of the oxides, with one ounce of powdered white sugar, divided into sixty tablets, to be taken in the same manner. The work, which makes a tolerably thick octavo volume, contains very copious illustrations of the subject, and also of the danger of the use of mercury, of which the examples are striking and well reported, M. Magendie, in conclusion, bestowed high praise on the assiduity and research of M. Legrand, and considered that he had established the beneficial nature of his remedy, although Royal Academy of Sciences of Paris. 151 in administering it great attention must be paid to regulate the doses according to the strength and constitution of the patient. The work has been published some years, but has only lately attracted the attention of the Academy. New Instrument for Lithotrity. — On the 16th of May, M. Leroy d'Etolies, to whom we are indebted for most of the instruments used in lithotrity, presented a new curved instrument, which he uses to break the stone, in cases in which a straight cylinder cannot pos- sibly be introduced. The Monthyon prize of six thousand francs was adjudged to M. Leroy for his various instruments. Anatomical Phenomenon. — M. Combetti, in the sitting of the 23d of May, read a memoir, containing the particulars of the case of a young girl, aged ten, who had recently died in the hospital for Orphans. Alexandrine Labrosse was born at Versailles in 1821 ; her father was healthy, but her mother weak, and worn out by excesses of every description. The child came into the, world meagre, but well formed ; it was very weak, and at two years old had not cut its first teeth. It was not able to articulate a word until after it was three years old, and could not stand alone until it had completed its fifth year. To this backwardness of corporeal developement was added a great imbecility of mind. At nine years old she was admitted into the Orphan hospital, at which time she was labouring under a pa- ralysis of the abdominal extremities. M. Combetti did not see her until January, 1831, when she had been three months in bed. Her face was pale, and her features emaciated and oppressed with stupor ; she never spoke, and, when addressed, replied in monosyl- lables, but always to the purpose; she lay constantly on her back, keeping her head inclined towards the left side ; she could scarcely move her legs, but they retained all their sensibility ; her hands were unaffected. She had long had glandular swellings of the neck ; she afterwards had a mild carbuncle on the buttock, and an ulceration of the foot. She was ultimately attacked by an intestinal affection, which carried her off on the 25th of March last. The body was dissected thirty hours after the death. The lungs were found crepitans, but full of miliary tubercles. The intestinal surfaces offered no appearance beyond what was usual in cases of similar disease. The cranium was of the ordinary thickness ; the meninges offered nothing particular, the brain appeared in its proper state, except that it was rather large. A small sanguineous effusion of recent date was observed in the thickness of the left posterior lobe. The tentorium of the cerebellum being opened, the marrow cut in the direction of the occipital orifice and the encephalic mass removed and turned over, there was observed — 1. a large quantity of serosity filling the occipital fossa ; 2. in the place of the cerebellum a cellular, ge- latinous, semi-circular membrane of about an inch and three quarters diameter transversely, and connected with the medulla oblongata by 152 Proceedings of the two gelatinous processes. Near these peduncles were two small white isolated masses about the fdze of a pea, upon one of which was one of the nerves of the fourth pair ; the quadrigeminal tubercles were unin- jured ; 3. no appearance of the fourth ventricle; 4. the pons varolii entirely wanting*, without any appearance ofdeperdition of substance ; the anterior pyramids terminated forkwise by the cerebral peduncle. It appears that the unhappy child had, from her earliest infancy, contracted habits of the most vicious self-indulgence; and M. Com- betti, in arguing on the foregoing facts, is disposed to attribute the absence of the cerebellum and pons varolii to a gradual destruction of those parts from disease, and not to any inherent defect of orga- nization. At any rate the case presents the extraordinary fact of the child having lived for some time in the possession of all its faculties, and even of a certain degree of intellect, though deprived of cerebellum, posterior peduncle, and cerebral protuberance. MM. Geoffroy St. Hilaire, Blainville, Magendie, Flourens and Serres have been appointed to examine and report on the case. Preservative against Smallpox and Measles. — On the 13th of June a letter was read from M. Remy, a physician at Chatillon, detailing some experiments which he had recently made on chloride of lime as a preservative against the small-pox. During the last autumn he had observed that, out of some hundred individuals whom he had vaccinated, nearly five-sixths had not taken the infection properly; whereas in the spring, although he had used matter precisely similar, every case succeeded. He then recollected, that during the autumn he had constantly carried in his waistcoat pocket a small packet of chloride of lime, and felt convinced that the non-reception of the virus must have been occasioned by that circumstance. He, therefore, in a village where the small-pox was raging with such violence that there only remained twelve individuals subject to the in- fection who had not been attacked, caused those twelve to be washed twice a week with a solution of chloride of lime, and gave them at the same time two drops of the solution in a glass of eau sucree. Two of them had a slight eruption similar to a vaccine, which has not taken well ; the other ten remained constantly with patients suffering from the small-pox, without, the least symptoms of illness. In another village where the small-pox also raged, there were fifteen individuals liable to take it; ten of them were subjected to a similar treatment, and wholly escaped the malady ; two of the other five caught the complaint. The same treatment was tried on four individuals under the influence of the small-pox ; the result was an increase of inflammatory symptoms, which were removed by bleed- ing; the progress of the eruption appeared arrested, the pustules remained in the same state as when first washed with the solution, and then dried away very slowly. This letter was referred to MM. Magendie and Serres. On the 20th of June, M. Chevalier reminded the Academy that he was the first who had suggested the use of Royal Academy of Sciences of Paris. 153 chloride of lime as a preservative against the small-pox, long before the experiments of M. Remy. He also stated that the chloride of lime might likewise be used as a protection against the measles, by keeping in the chamber of the child whom it was desired to preserve from infection a saucer of dry chloride of lime, renewed from time to time, and dipping its shirts in a solution of one ounce of concen- trated liquid chloride in twelve quarts of water. Cholera Morbus. — On the 20th of June a letter was read from Dr. Foy, an eminent physician at Warsaw, the contents of which tend to prove that whatever may be the contagious properties of this disorder, their effect mainly depends upon the predisposition pro- duced by the constitution and habits of those exposed to their influence. Habitual intemperance, disorderly living, and want of cleanliness, will generally expose those addicted to them to the im- mediate attacks of the disease, while the contrary habits will almost invariably be found preservatives. Dr. Foy imagines that the cholera has its seat in the spinal nervous system, and that all the functions of the skin being impeded, their restoration to their natural activity is indispensable to a cure ; hence in the Russian sol- diers, whose habits are disgustingly dirty, and whose skin Dr. Foy tells us was, in many instances, covered with filth of more than a twelfth of an inch in thickness, the disease generally terminated fatally. Dr. Foy exposed himself in every mariner to the infection ; he infused into his own veins the blood of an individual at the point of death from cholera ; inhaled the breath of patients suffering under the disease; and even tasted the matter ejected from their stomachs, without sustaining any injury from the experiment beyond a slight nausea and head-ache. Dr. Foy's letter was accompanied by official certificates, affording guarantees of his experience and credi- bility. He also stated that the use of the tincture of nux vomica had been unsuccessful, but that some practioners had lately used, with good effect, chloride diluted with water. Lacteal Infection. — The same day M. Guyon communicated to the Academy the death of an infant and a dog, who had partaken of the milk of a woman suffering from fever. The former died in thirty hours, and the latter in less than four, exhibiting all the usual symp- toms of death from poison. ZOOLOGY. History of Zoology. — On the 26th of March, M. Geoffroy St. Hilaire read a memoir entitled * Du degre* d'influence du monde ambiant pour modifier les formes animates composant le caractere philosophique des faits differentiels.' It is impossible to follow the learned professor through his discursive, argumentative theories ; it will be sufficient to state his general views, which always possess novelty and ingenuity, and often valuable truth. He commences 154 Proceedings of the by distinguishing the following epochs of the science of zoo- logy:— In the first, man regarded animals merely as he was in- duced to seek or avoid them ; in the second, he was led by curiosity to examine their different forms, independently of their actual utility ; in the third, he felt the necessity of characteristic signs and marks of distinction. The fourth was occupied by the details of nomenclature, description, and classification. In the fifth, zoology attained the rank of a science, properly so called ; and the era of philosophical inquiry into the natural relation between the various classes commenced. During the sixth, the idea of a primitive iden- tity of organization began to develope itself, though in a somewhat vague and uncertain manner; and in the seventh, at which we are now arrived, science is occupied in developing the external causes in which originate the various modifications which that primitive iden- tity of organization has undergone in various animals. He remarks, that in order to appreciate the action of external circumstances upon an organized being, it is not sufficient to consider that being in its perfect state of developement, we must study it at different periods of its life. Thus we could not find any good reason for the depressed and semi-elliptical form of the head of the frog, if we confined our inquiries to the full-grown animal; but in tracing its origin, we find that the frog, in its tadpole state, partook of the organiza- tion of fishes, that is to say, it breathed through the voluminous gills placed under the back cranium. Now, the bones of the auricular region are the parts covering the gills, so that their deve- lopement must necessarily be in proportion to the volume of those gills ; thus the disposition of the bones of the head of the frog has relation to the aquatic respiration of the tadpole. M. St. Hilaire then traces the changes of organization through the various phenomena of the universe, showing how the organic developement of animals may have been affected, at various periods of their existence, by the external changes in the material world. He particularly dwells on the changes which may have been produced in the organs of respiration, and the organs dependent on them, by the changes which have gradually taken place in the atmosphere and tempera- ture since the primitive ages ; by which he endeavours to account for the modifications which, from a comparison of fossil remains with existing animals, appear to have taken place in various species of the animal kingdom. It is certain, he says, that the atmosphere is no longer what it was, either in its chemical or physical proper- ties ; and as the atmosphere cannot be modified without the respira- tion, and consequently the whole animal economy, being modified also, it follows that the existing animals, though descending directly by way of generation from the ante-diluvian animals, differ materially from them in organization. Man undergoes a change something similar; it often happens that, in consequence of a germ being placed in circumstances different from those in which it ought naturally to be placed, the being to which it gives birth does not resemble its Royal Academy of Sciences of Paris. 155 father ; we then call it a monster, but all the individuals which we consider normal, would be monsters if considered in reference to their original progenitors. Lusus Natures. — On the 18th of April, a communication from M. Leon Dufour, Corresponding Member of the Institut, was read to the Academy. It contained a curious account of an anomalous growth of hair in the region of the sacrum of a young man whom he had recently had occasion to examine for the conscription. This mass of hair perfectly resembled that of the head, both in length, colour, and quality. The skin from which it sprung was as white as the surrounding parts, thus preventing the possibility of the phe- nomenon being referred to the class of defects known by the name of moles, in which the colour of the skin is always dark, and the hair coarse and short. M. Dufour characterises the case as falling under that class of exceptions to the usual laws of organization which are designated as rudiments, and considers it as presenting the character common to several mammiferce, of having the lower extremity of the vertebral column covered with long hair. The young man in question did not present any extraordinary develope- ment of the vertebrae of the coccyx, and may, therefore, be consi- dered as complete an anomaly as the woman with four breasts and a cow's tail, mentioned by Voltaire in his * Philosophical Dictionary.' On the 23d of May, M. Fabre handed to the Academy a foetus, which had come to its full term, and even lived a quarter of an hour, having but one eye placed in the centre of the brow, and ap- pearing to result from the junction of two eyes closely united. There was no external appearance of nose. Fossil Remains. — At the meetings of the Academy, on the 2nd and 9th of May, M. Geoffrey St. Hilaire communicated various particu- lars relative to some fossil remains discovered at Caen, which belong to an animal named by him the ielco-squrus. He exhibited several drawings of these fragments, and also the ventral and dorsal cara- paces of the animal : the former differs from that of the crocodile, which has no bony scales, whereas that of the fossil animal is com- posed of strong bony pieces, while a plate, equally hard, and of proportional dimensions, is under the throat, having, however, two sloping cuts, to admit of the lateral movement of the head ; the latter is composed of bony scales, placed over each other, nearly in the same manner as those of the crocodile. From the peculiar organi- zation of these animals, the learned professor concludes that they could never have breathed in an atmosphere similar to that in which we now live, but must have existed at a period anterior to the crocodiles and other animals of that species. The teleo-saurus must necessarily have been a marine animal, and must be referred to the same period as the ichthyosauri, the gryphites, the nautili, and other 156 Proceedings of the molluscs, the remains of which form a part of the marine deposits known by the name of terrain secondaire, or Jurassic formations. No feet of this animal have ever been found ; but in the cabinet at Caen there is a block containing the imprint of the whole skeleton of a stcneo-saurus, in which is observed the form of the first joint of the hind feet, which resembles that of the ikan dugung. It appears that there was but one middle toe, of a length beyond all proportion, accompanied by the rudiments of a lateral joint, thus, in some re- spects, resembling the horse, but as well adapted for swimming as the horse's hoof is for walking. M. St. Hilaire, however, thinks it probable that the feet of the teleo-saurus were different from those of the steneo-saurus, inasmuch as there certainly existed great difference in the other parts of the organization. Thus the nostrils of the former are entirely terminal, giving the idea that the muzzle termi- nated in a sort of snout, while those of the latter are open at the top, nearly in the same manner as those of the gavials. The teeth also of the steneo-saurus resemble those of the gavial, while those of the teleo-saurus are thin, and spring laterally ; hence it may be supposed that the former preyed on living animals, while the latter lived on submarine vegetables and algae : indeed, from the granite stones found in the midst of the fossil bones, M. St. Hilaire was inclined to believe that the animal swallowed stones, for the purpose of bruising and facilitating the digestion of the herbs and grains. From these examinations M. St. Hilaire deduces a theory, that there have been three epochs of animal creation. In the first, (to which belongs the teleo-saurus,) animals, without lungs, existed alone ; in the second, animals with pulmonary organs began to appear ; arid in the third, which comprehends the present world, the earth was covered with animals of a species of which no analogous fossil re- mains have been discovered. It results from this theory, that man is of a very modern origin as compared with the age of the globe. Bicephalous Lizard. — On the 9th of May, M. Beltrami commu- nicated some curious particulars relative to the two-headed lizard men- tioned in our last Number (page 570), which lived five months in the possession of M. Rigal, an apothecary at Argelles. It used its two heads simultaneously for eating when it could seize its food as it liked. If a single insect were presented to it, both heads attempted to seize it, and the one which failed endeavoured to snatch it from the other. When, however, one head was satiated, the other refused food, but if water were offered, the head which had not eaten would drink for the other, which then, in its turn, refused to drink when its companion was satisfied. The animal has five feet, four of which, placed in the usual position, served it for locomotion ; the fifth is situated at the point of junction of the two necks, at the upper part of the common body. It has nine distinct toes, evidently resulting from the union of the two fore-feet. This foot, or paw, served it to clean itself, and to carry the food alternately to the two mouths ; and Royal Academy of Sciences of Paris. 157 it was remarked that it never presented food to the same head twice in succession, and if it had commenced with the right hand one, it invariably finished with the left. The two heads and necks are of equal dimensions, and perfectly well formed. M. Rigal had endeavoured to preserve the animal from the cold of the winter before last, by keeping' it in bed during the night, and found it one morning smothered to death. It has been preserved in spirits of wine, and deposited with the Secretary of the Academy. Collection of Natural History. — At the same meeting, M. Cuvier mentioned in terms of high eulogium the collection brought from India by M. Delamare-Picot, which he characterized as the most extensive ever made by an individual unaided by funds from govern- ment. In the zoological department it comprises 53 species of mam- miferae, 123 of fishes, 52 of Crustacea, 150 of insects, 40 of zoophytes, 30 of reptiles, and 75 of birds; there were more than 400 of vege- tables. Many of these species were hitherto unknown, and others were wanting in the Museum of the Jardin des Plantes, particularly the rhinoceros without horns, known by the name of the rhinoceros of Java. The mode adopted by M, Picot for the preservation and transport of his vegetables is worthy of observation. After having dried the plants in the ordinary manner, instead of placing them between sheets of paper, he put them all, pressed one immediately over the other, into flat shallow boxes, the interior of which was covered with oil of petroleum, and which were supplied with cam- phor and pepper pounded together, and carefully closed in all the joints. The vegetables, so packed, were not injured, either by the damp or by insects, under circumstances in which ordinary herba- ries were completely destroyed. The adoption of this plan would save botanists a great deal of trouble and anxiety, and relieve them from the masses of paper which they are now obliged to carry. On the distinguishing Marks of Venomous Serpents. — On the 16th May, M. Cuvier read a report on a very important memoir by M. Dtivernoy, Professor of Natural History at Strasburg, the object of which is to point out the means of distinguishing those serpents whose bite is rendered dangerous from the venom which they instil into the wound, from those whose bite is accompanied by no evil consequences beyond those of the wound itself. The attention of naturalists has long been directed to this subject in vain. It was formerly supposed that the existence of plates or scales on the top of the head was a sufficient criterion ; but a further acquaintance with the reptile tribe has proved that the rattlesnakes, the trigono- cephalus, the nain, all of which are decidedly venomous, are furnished with these scales, as well as the most harmless snakes. It was after- wards thought that the jaw, remarkably moveable, and furnished with a large hollow fang, was a sign easy to be recognized, and, in fact, all serpents in which that peculiarity is observed are venomous, 158 Proceedings of the but it has been discovered, some years since, that there are serpents, the jaw of which has not that moveable character, and contains as many teeth as the common snake, but which has in front a fang not easily perceived, but hollow, and instilling venom. But even this was not sufficient, as MM. Leschenault, Delalande, and Boy& ascer- tained that some serpents, which certainly had no hollow fangs in front of the jaws, were unquestionably of a venomous nature ; and it therefore became necessary to seek in some other part of the mouth the source of the poison. Accordingly, MM. de Beauvois, Reinward, Boye, and Cuvier ascertained that the serpents in question have, in the back part of the jaw, some teeth which are longer and stronger than the others, and are sometimes hollowed in a manner which may be supposed as well adapted to convey poison into wounds as the hollow fang of the viper. The important point to ascertain, therefore, was whether these back teeth were, in fact, connected with glands of a venomous character or not. M. Schlegel, in a memoir printed in 1828, in the 14th volume of the * Memoirs of the Academic des Curieux de la Nature,' had commenced the inves- tigation, and pointed out the particular glands to which these hollowed back teeth can serve as conducting canals, and which glands may be co-existent with the ordinary salivary glands, as he particularly noticed in the homalopsis monilis. M. Duvernoy, who was not acquainted with the memoir of M. Schlegel, has carried his investigations to a much greater extent, and has given a far better account than previously existed of the venomous and salivary glands, and such parts of osteology and myology as relate to them, and which he has illustrated with carefully executed plates. His observations have been principally directed to the following species : non-venomous, the tortrix scytale, the coluber natrix, the coluber quincunciatus, the elaps lemniscatus, the vipera verus, the naia tri- pudians, and the crotalus durissus ; venomous, with numerous maxillary teeth, the baugarus fasciatus and the pelanus bicolor ; and finally, among those suspected of venomous properties, on account of the long back teeth, the coluber plumbeus, the dipsas interruptus, and the homalopsis pantherinus. In describing, in a very perfect manner, the general and particular characters of the organs of de- glutition and insalivation, M. Duvernoy had added to, and rectified the previous observations of M. Dugez, particularly with respect to the adductor muscle of the jaws, which he considers to be a dismember- ment of the mylohyoidean as well as the mylovaginian of M. Dugez, which is attached to the skin above the large scales of the under jaw. M. Duvernoy has also entered into minute inquiries as to the proportions of the lachrymal gland, and the variation of its position within and without the orbit in different genera and species, and also as to the analogy between the developement of that gland and the salivary and venomous glands, and the size of the eye, a point which had been left untouched, even in M. Cloquet's work on the lachrymatory organs of serpents. There are also several new Royal Academy of Sciences of Paris. 159 details on the variations in the size and developement of the sub-maxillary or common salivary gland, depending on the existence or non-existence of a venomous gland. All M. Schlegel's observa- tions on the difference and co-existence of the two glands had been previously noticed by M. Duvernoy, who adds to them several new remarks, particularly respecting the muscle of the venomous gland, which appears to be an external temporal muscle, generally attached to the envelope of the gland, and descending to .the lower jaw, without being attached to the top of the temporal fossa, but occa- sionally, as in the naia and the bougares, composed of two distinct portions. His most particular attention, however, was directed to the serpents having the long back teeth, for the purpose of ascer- taining in which of them there exists the venomous gland, and in which this elongation of the teeth does not denote any specific se- cretion. When this gland does exist, it is frequently joined to the sub-maxillary gland by a very thick cellular tissue, and may, there- fore, be easily confounded with it. The existence of this gland is certain in the coluber Esculapii of Linnaeus, in the coluber cerberus of Dandin and Cuvier, the homalopsis pantherinus of Boye, and in a dipsas, the baugarus interruptus of Oppel ; all those, there- fore, are venomous, and illustrate the observations of M. Boye, who had ascertained, from experiments made while the reptiles were living, that the dipsas and the homalopsis are venomous. The genera dendrophis, dryenus, and ocenodon have also the back teeth large, and even in the dryenus nascetus, the largest tooth is hol- lowed like a canal ; but as M. Duvernoy has not found any specific or venomous gland, he concludes that they are not poisonous. These circumstances explain the contradictory testimony existing respecting the venomous qualities of particular serpents, and at the same time prove that the class in question must be far less dan- gerous than those in which the fang conducting the poison is in front, because unless the object bitten be sufficiently small to admit of its being taken into the mouth of the serpent, and thus brought into contact with the back fang, no poison will be communicated to it, and only a common wound be produced ; so that a person bitten in the leg or arm would suffer no injury beyond the actual bite, while another, whose finger was inserted into the mouth of the reptile, would be poisoned. Hence, M. Duvernoy concludes that the prin- cipal use of these posterior fangs is to kill the small animals which the serpents take into their mouths alive, and that they are not of much advantage as a means of attack or defence against external enemies. In the course of his Memoir, M. Duvernoy remarks, that in many serpents the spleen is closely attached to the pancreas, which probably led M. Mecke) into the error of doubting its exist- ence. This memoir was ordered to be inserted in the * llecueil des Savans Etrangers,' and the various preparations presented to illus- trate the subject were deposited in the Gallery of Anatomy in the Museum of Natural History. 160 Proceedings of the Organic Symmetry. — On the 23rd of May, M. Dutrochet, a Cor- responding- Member of the Institute, addressed a letter to the Academy, relative to the want of symmetry observed in the internal organs of a great number of animals arrived at their fullest state of developement. He does not agree with Bichat,in supposing this want of symmetry to be an essential character of the organs ; but, on the contrary, agrees with M. Cuvier, that in animajs with long bodies there is an evident symmetry existing, which is still more striking in the foetus during the first periods of its existence : the alimentary canal is then extended in a right line from the mouth to the anus, and is perfectly symmetrical. In the original plan of organization, the symmetry was as perfect internally as it is externally ; and if it be afterwards destroyed, it is by a species of abortion of one of the sides. In the larva of the aquatic salamander, when it first leaves the egg, the alimentary canal is perfectly symmetrical. On its two sides, near the beginning of the intestine, are perceived the liver on the right, and the spleen on the left, forming almost a perfect symmetry, as there is scarcely a per- ceptible difference of size, and the form, as well as the position, is precisely similar. In process of time, however, the left livei\ or spleen, becomes an abortion, and is consequently without functions ; so also in the primitive organization of insects, the biliary organs are symmetrical. Sometimes two symmetrical organs will both become abortions : they will then be useless to the body, serving only as indications of the primitive organization. Such M. Dutrochet sup- poses to be the history of the capsule renales. * Classification ofLusus Nature. — On the 1 1th of April, M. Geoffroy St. Hilaire communicated the substance of a memoir which he had prepared, on the classification of a particular family of lusus naturae, which he considers as forming a regular series of anomalous beings, the fundamental character of which depends on the union of the upper part of the nervous cerebro-spinal system of two individuals in a single system, which is either doubled by the fusion of two complete systems, or single by the combination of two corre- sponding halves. The encephalus is to be considered as composed of four systems of lobes — the spinal marrow, the cerebellum, the optic or quadrijumal lobes, and the cerebral lobes. In the family in question, the ventral regions remain distinct ; the two beings are perfectly separate, and subject to the ordinary rules of organiza- tion below the navel, but above it they are united and confounded. The vertebral columns inclined forwards unite beyond the atlas, and each produces half of the cephalic elements which terminate them. The following are the names and characteristics of the four classes into which M. St. Hilaire divides this family: — 1. Deradelphus — Cephalic elements double as far as respects the medulla oblongata and the occipital part of the brain (hypertrophie de V occipital). The rest of the head single. Royal Academy of Sciences of Paris. 161 2. Synotus. — Cephalic elements double as to the medulla ob- longata and cerebellum ; the rest of the head single. Ears super- numerary, and united behind the head. 3. Eniops. — Cephalic elements double as to the medulla ob- longata, cerebellum, and optic lobes; rest of the head single. Supernumerary ears behind the head, and an additional eye in the sinciput. 4. Janiceps. — The whole encephalus and organs of senses double ; the faces opposite each other. Examples exist of each of these classes, but the first has only recently been met with. The name given by M. St. Hilaire to the family is that of " Monstres bicorps unicephales." MISCELLANEOUS. Chronology of the Egyptians. — A considerable portion of the sittings of the 4th and llth of April was taken up by the communi- cation of a memoir by MM. Biot and Champollion on this interest- inn; subject. It is well known that the Egyptians divided the year into twelve months of thirty days each — which, with five intercalary or supplementary days, completed the number of 365. Twelve great divinities presided over the twelve months of the year, five others over the five intercalary days ; thirty genii regulated the thirty days of the month ; and the twenty-four hours of the astro- nomic day were under the protection of twelve gods and the same number of goddesses. This year of 365 days was, however, about a quarter of a day shorter than the solar year, whence the first day of the month of Thot, which began the year, was perpetually in advance of the sun's progress in the ecliptic: so that if the 1st of the month of Thot occurred at the vernal equinox, it would, in four years* be one day before it; and so on in progression until the ex- piration of 1506 years, when it would again occur at the precise period of the equinox. Hence the Egyptian year was termed annus vagus ; and so great was the attachment of the country to it, that the kings, on coming to the throne, were compelled to take an oath against allowing any change to be made in the mode of computing the year ; and the compulsory correction made in the calendar by Augustus, twenty-four years before Christ, was considered one of the bitterest fruits of the Roman conquest. This attachment was not founded on ignorance ; on the contrary, the Egyptians were well aware that the solar year was about a quarter of a day longer than their annus vagus, and were probably even the first to commu- nicate that fact to the Greeks. This strong attachment to the annus vagus is the more remarkable, when we consider that none of their monuments give us any reason to suppose that these years were connected by them in any regular chronological series ; on the con- trary, all the Egyptian dates which have reached us are reckoned VOL. II. AUG. 1831. M 162 Proceedings of the from the commencement of the reign of each king: so that, in order to establish the historical succession of events, it would appa- rently be necessary to have a chronological canon, indicating the number of years of each reign ; and many antiquarians have sup- posed that this was the case. It is, however, singular, that in the numerous Egyptian monuments with which we are acquainted we find no traces of any such canon — except, indeed, the chronological canon of Ptolemy, and the fragments of the chronicle of Manetho, both of which are of very limited extent. M. Biot seeks to prove, that the attachment of the Egyptians to the annus vagus arose from the fact of its containing a natural cycle, specially adapted to their country : so that, by means of symbolic signs attached to the different days of the annus vagus and to certain epochs of the true solar year, they could, with the utmost facility, connect these two systems of years, and thus fix the dates indicated by the anni vagi, with as much pre- cision as we can do by our present calendar. M. Champollion, in his late researches, has ascertained that the Egyptians divided the year into three equal portions of four months, or 120 days each (the five supplementary days having a separate and distinguishing mark) : these were represented by symbols illustrative of the periods of vege- tation, harvest, and inundation. The inundation of the Nile com- mences invariably at the summer solstice: it attains its greatest elevation in 100 days, and then, after remaining stationary a few days, it begins to recede, and the ground is sown while yet moist; so that in 120 or 125 days after the summer solstice, the period of inundation ends, and that of vegetation commences. Four months afterwards the harvest begins, and lasts four months ; and thus ends the agricultural year. The Egyptians were well aware, that as the inundation of the Nile invariably commenced at the summer solstice, which would therefore be the first day of the ninth month, or third period of the year, the first day of Thot (the first month) ought to be 125 days after that solstice. They had, therefore, only to observe the degree of variation existing between the time of the solar year at which the 1st of Thot occurred in any given year, and that at which it ought in reality to be found, and a perpetual and unfailing calendar was at once constituted, showing with the utmost precision in what part of the cycle of 1506 years any given year was. It only remained then to ascertain how many of these cycles there had been, or, in other words, when the Egyptians first adopted the mode of computation by the annus vagus, and observed its variation from the true solar year. It is evident that the system must have commenced at a period when the solar year and the annus vagus were in accordance; and as we know that when Augustus altered the mode of computing the year, twenty-four years B.C., the 1st Thot of the annus vagus corresponded with the 29th of August, it is easy, by fixing the date of the summer solstice, to ascertain when the 1st day of Thot did in fact occur 125 days after the summer solstice. The following table shows all the Royal Academy of Sciences of Paris. 163 periods before the Christian era at which that coincidence took place :— Julian era. Years before Christ. Date of IstThot. Date of Summer Solstice. 76 4790 December 4 August 1 1429 3285 November 22 July 20 2934 1780 November 11 July 9 4439 275 October 31 June 27 It is therefore to one of these four periods that the commence- ment of the Egyptian mode of calculation must be attributed. The last of the four may be excluded from our consideration, because the researches of M. Champollion have proved incontestably that the an mi* vagus of 365 days was used by the Egyptians previous to the year 1600 before Christ. We have therefore only to examine the probability attaching to the first three ; and for this purpose it is important to remark that the Egyptians, in their mythological sys- tem, considered the star Sirius as the power influencing the rising of the waters of the Nile ; and therefore it must be presumed that their system commenced at a period when the heliacal rising of Sirius coincided with the summer solstice, or rising of the Nile. This occurred for the first time in the year 3285 B.C., previous to which the rising of Sirius was more and more removed from the summer solstice; the date of 4790 B.C. may therefore be also put out of the question, and the doubt only remains between the years 3285 and 1780 B.C. The first, as we have before seen, coincides precisely, and therefore furnishes a fair presumption that the Egyp- tians at that period formed their year of 365 days ; but we cannot be quite certain of the facts, because, supposing the addition of the five days not to have been made until 1780, and consequently cal- culating backwards by years of 360 days, we should only make a difference of six Julian years, placing the period of coincidence between the summer solstice and the 1st day of Paschous (the ninth month) in the year 3291, when the heliacal rising of Sirius differed only a day and a half from the summer solstice — an error which may easily be committed in determining the heliacal rising of a star from observation only. From these observations, we arrive at the following important conclusions: — 1st. That the Egyptians, knowing that the cycle of variation between the solar year and the annus vagus consisted of 1506 years, could always tell, by observing the number of days which the 1st of the 9th month (Paschous) varied from the summer solstice, in what year of the cycle they were ; and that at the time of the alteration of the year by Augustus they could not be in more than the third, and perhaps only in the second of such cycles from the time of their first calculating in that manner. 2nd. That as all the data on which this calculation of the year is founded relate to the phases of the Nile, it is evident that it is of Egyptian, and not of Chaldaic origin. 3rd. That as the phenomena relating to the Nile continue at the present moment to occur in precisely the same manner and at the same intervals as at the commencement of the Mi 164 Proceedings of thti Egyptian calculations, it is evident, that for 5000 years the distri- bution of the terrestrial heat on the surface of the earth has remained the same, as any change must have affected the periodical rains of Upper Ethiopia, the rising of the Nile, the duration of the inunda- tion, &c. Protection of Firemen. — On the 4th of April, M. Gregori com- municated some details of the experiments recently made in Italy by the Marquess Origo, the commandant of the firemen at Rome, with a view to guarantee them from the effects of entering houses while a prey to conflagration. Acting on the received opinion that the Romans employed a mixture of clay and vinegar to extinguish flames, he tried that mixture in every manner, but it produced no satisfactory result. He then dipped two complete suits of firemen's dresses, including boots, gloves, and two cowls, made of the same cloth as the dresses, in a solution of sulphate of alumine and sulphate of lime, and, when dry, saturated them with soap water. Two firemen were clothed in these dresses, and their faces covered with incombustible masks, covered with cloth saturated with a saline solution ; the openings for the eyes were covered with a web of amianthus, and small damp sponges were placed in their mouth and ears. Thus protected, they entered a house, 23 feet long and 3 feet wide, filled with burning wood, which they traversed ten times without the slightest injury. Their clothes were not damaged, although they had remained fifteen minutes exposed to the action of the flames. The only effect produced on the men was the increase of the pulsation from 70 to 125. These dresses cost but two pounds sterling each ; and are, therefore, in that respect, more eligible than those composed of amianthus, as recommended by the Chevalier Aldini. M. Origo also extinguished flames of considerable violence by playing on them with the solution of sulphate of alumine and clay, by means of a common engine. Transport of Edifices. — On the 9th of May, M. Gregori alluded to a circumstance mentioned in a late Number of the ' Journal des Artistes,' of a rock of granite, 42 feet long and 27 high, having been transported from the bay of Finland to St. Petersburgh, to serve as a pedestal to a statue of Peter the Great. He stated that a much more remarkable fact had occurred at Crescentino in 1776, when a common mason, named Serra, succeeded in transporting a brick belfry (which he had contrived to cut from its base without injuring' the walls) from one church to another, at a considerable distance. While it was being moved, a man inside rang the bells. A model of the machine, employed in the transport, was deposited in the library of the Institute, Travelling in India. — At the same meeting, M. Elie de Beau- mont read extracts from two letters, which he had received from M. Victor Jacqueminot, a French naturalist, travelling in India, M, Royal Academy of Sciences of Paris. 165 Jacqueminot censures the name of Valley of Dhoon, given by the English to the valley at the entrance of the Himalaya, as being a mere pleonasm, the word Dhoon signifying valley. The Valley of Dheynia is its proper name: it is a longitudinal valley, hollowed between the foot of the Himalaya, properly so called, and the raised diluvial earth. Thence he visited, on foot, the sources of the Jumna. In this expedition he passed over heights of an elevation of 5550 metres (18,208 English feet). He penetrated more than once into the Chinese territories ; and, in returning towards Ladack, he slept at a village called Ghyournneul, situated on an elevation of 5000 metres : on the Indian side of the Cordilleras, he did not observe any village at a greater elevation than 2700 metres. Cultivation, also, on the south side, stops 2000 metres below the level which it attains on the Thibetian sides of the descent. This difference arises not so much from the temperature as from the state of the sky, which is cloudy and rainy on the Indian side, and pure and free from humidity on the other side, of the Himalaya. From a variety of geological observations, M. Jacqueminot is induced to think that there exists a difference in the age of the Thibetian and southern chains of the Himalayan mountains ; an observation which M. de Beaumont had already made relative to different chains of the Alps. M. Jacqueminot also mentions the uncertainty of correspondence in that part of the country, — as, in addition to the ordinary casualties of letters, the couriers between Benares and Calcutta are occasionally devoured by the tigers en route. Paganini. — On the 16th of May, Dr. Bennati read a physiological notice of this extraordinary man, in which he gives it as his opi- nion, that the prodigious talent of this artist is mainly to be attri- buted to the peculiar conformation which enables him to bring his elbows close together, and place them one over the other, and to the elevation of his left shoulder, which is an inch higher than the right one — to the slackening of the ligaments of the wrists, and the mobility of his phalanges, which he can move in a lateral direction at pleasure. Dr. Bennati also alluded to the excessive developement of Paganini' s cerebellum, as connected with the extraordinary acute- ness of his organs of hearing, which enables him to hear conversa- tions carried on in a low tone at a considerable distance. M. Geoffroy St. Hilaire remarked that he had been particularly struck with the prominence of the artist's forehead, which hangs over his deeply- seated eyes like a pent-house. Oil Cloths. — On the 23d of May, M. Chevallier pointed out a very simple method of removing the unpleasant smell which has hitherto militated against the use of oiled or varnished cloths and stuffs. It is merely to expose them to the action of a chloric fumi- gation in a close room. Prevention of Falsification of Written Instruments. — The atten- tion of the French government has long been directed to the possi- bility of rinding some means of preventing writing being chemically 166 Proceedings of the discharged from papers and other documents, either for the purpose of falsifying the contents, or for making a second and fraudulent use of old stamps. With this view, the Academy of Sciences was directed to take the subject into consideration ; and a committee, consisting- of MM. Gay Lussac, Dulong, Chaptal, Deyeux, Thenard, D'Arcet, Chevreuil, and Serullas, was appointed for the purpose. The attention of the public was called to the subject, and a great number of specimens of ink, alleged to be indelible, were forwarded to the committee. Numerous experiments were made ; and on the 30th of May and 6th of June the report was read to the Academy by M. D'Arcet. It is unnecessary for our purpose to follow the reporter through his elaborate history of the different manufactures of ink in different ages, or the detail of the experiments made with the various samples submitted to the committee : it is sufficient to state the conclusions, which were unanimously adopted as the results of the investigation. These were, that the falsification of written documents will be fully prevented by the use of ink prepared in either of the two following manners. 1. Indian ink (or, in its absence, the imitation of it made in Europe with soot and animal glue or gum), dissolved in a mixture of water and muriatic acid, of the specific gravity of 1010 (li degree of Beaume"s instrument.) This ink may be prepared for fourpence English per quart. 2. To a solution of acetate of manganese, of the specific gravity of 1074 (10 degrees of Beaume), add half its volume of solution of carbonate of soda crystallized, saturating it at about 166 percent. : dissolve Indian ink in this liquid, and writing traced with it will become perfectly inde- lible on being exposed to the action of the vapour of liquid ammonia. The committee lay down, as a general principle, that no ink, kept in a liquid state, can be indelible, as the colouring matter, from its excess of density, will necessarily be deposited. Additional security will be obtained by writing on paper so prepared, that even if the ink could be discharged, it would necessarily be seen that it had been so discharged. Thus, M. Coulier proposes a paper, having printed on each sheet, lines and patterns, so complicated, as to defy forgery, and struck off from a steel plate damasked with aqua-fortis. The ink with which this is printed would be discharged by chlorine, so that the superjacent writing cannot be destroyed without also de- stroying the drawing. This plan is excellent for bills of exchange and other small documents ; but from the expense and delay occa- sioned by the engraving and printing, the designs would be ill adapted for legal proceedings and public documents. M. Chevallier proposes a paper coloured in the pulp with colours liable to be dis- charged by all the known re-agents, but this might easily be re- coloured when the alteration is made. M. Maimu suggests adding to the pulp of the paper filaments of wool, cotton, or hemp, dyed of different colours, some of which will be acted on by the acids, and others by the alkalies, but all liable to be discharged by chlorine. When these colours are discharged, it is almost impossible to restore them ; but the writing may, in some cases, be effaced without any Royal Academy of Sciences of Paris. 167 sensible alteration in the colour of the filaments ; and on the other hand, that colour will frequently change by simple exposure to the air, without any re-action being used. Mr. Coulier's method is by far the best, but has the disadvantage, that all designs easily dis- chargeable from the papers may become injured by time or acci- dental circumstances, a consideration which, in cases of forgery, would tend to render probable the impunity of the guilty by the fear which would be entertained of condemning the innocent. The use of these prepared papers must, therefore, be considered as very secondary, the main security must be found in the indelible inks. The discharge of the writing from old stamped documents, and the consequent fraudulent use of the stamp, may be prevented, 1st. By printing on all stamped paper, by means of a cylindrical press, an engine-turned vignette, placed on the right of the stamp, in the centre and along the whole length of each sheet. 2nd. By employ- ing, in printing these vignettes, a colour having for its base the black precipitate formed in the dyeing coppers of hatters, or ink thickened in the manner adopted in the manufactories of painted cloths ; and 3rd. By marking on all stamped papers the date of their fabrication, either by printing it in the pulp, or engraving it on the vignette or the stamp ; or, more simply still, by making the dry stamp, impressed on each sheet of paper, revolve, so as to affix a new date each year. This report was ordered to be transmitted to the Minister of Justice. Gelatine. — The discovery of Mr. D'Arcet, member of the Insti- tute, of the means of preparing the gelatinous matter of bones, so as to form a cheap and wholesome article of food, has excited great attention in Paris. More than two years have elapsed since the dis- covery, and the system of M. D'Arcet has been adopted in several of the hospitals, and in the Maison de Refuge pour I Extinction de la Mendicite of M. de Belleyme. The gelatine has also been used in making sea-biscuits, which were used by the troops during the late expedition against Algiers. The mode of preparing both the gela- tine and the biscuits is minutely laid down in the pamphlets pub- lished by M. D'Arcet. These experiments had invariably been at- tended with success ; but on the 6th of June, M. Donne, a young medical student, communicated to the Academy some remarks tending to throw a doubt on the subject. He stated, that being deeply impressed with the importance (particularly to the lower classes) of ascertaining whether the gelatine did really possess the nutritive qualities attributed to it by M. D'Arcet, he resolved to go through a series of personal experiments on the subject. With this view, recollecting that ten grammes of dry gelatine were stated to be equivalent to half a litre (about two basins) of the best meat broth, he began by taking that quantity every morning with three ounces of bread, and gradually increased the quantity up to fifty grammes, which constituted his sole nourishment up to six o'clock every day ; 168 Proceedings of the the gelatine was differently flavoured, so as to prevent its exciting any feeling of nausea or disgust. During the six days which this experiment lasted, M. Donne experienced a constant sensation of sinking and feebleness, and on the sixth day found that he had lost two pounds weight. The next week he substituted ordinary meat broth for the gelatine, taking a litre and a half (about five or six bowls), and from four to five ounces of bread daily ; during this •week he experienced no sensation of feebleness, and at the end of it had regained a pound and a half of his lost weight. At the same time M. Donne tried similar experiments on two dogs, giving the one, gelatine mixed with a little bread, and offering the other nothing but simple gelatine. The former at first refused it, but at length ate daily as much as was equivalent to twelve or fifteen half litres of good broth. On the sixth day the dog had lost four ounces in weight, and was so voracious that he even greedily devoured some white lead prepared for cleaning plate, and during the second week totally refused gelatine, living only on about an ounce and a half of bread •which was given him per day. He ultimately terminated the expe- riment by climbing to a great height, and taking possession of a quantity of boiled beef which was supposed to be out of his reach. The other dog could not be prevailed on to touch the gelatine, even after being for five days totally without food. M. Donne", therefore, considered it cruel to pursue the experiment further, and gave him his usual food. From these circumstances M. Donne was induced to doubt the nutritive qualities of gelatine, and begged the Academy to appoint a committee to investigate the subject, which was accord- ing done. At the succeeding meeting (13th June) M. D'Arcet ad- dressed some observations to the Academy on the subject alluded to by M. Donnd ; he stuted that butchers' meat contained, on the average, in every 100 Ibs. — Dry meat . . 24 Ibs. Water ... 61 Bone .... 15 — 100 Bones contain, on an average, Earthy substance . 60 Ibs. Gelatine 30 Fat 10 — 100 From this calculation it is evident that the 15 Ibs. of bone con tained in every 100 Ibs. of meat would furnish -ffc of their weight, or 6 Ibs. of animal substance, so that 100 Ibs. ot meat, which now furnish but 24 Ibs of dry meat, miiiht, by rendering the gelatine and fat of the bones available, supply thirty, or, in other words, four oxen would furnish as much alimentary substance as is now obtained from five. "With respect to the nutritive and salubrious qualities of gelatine, he remarked, that the committee appointed by the Faculty of Medicine, consisting of MM. Le Roux, Dubois, Pelletau, Du- • Royal Academy of Sciences of Paris. 169 meril, and Vauquelin, after having given gelatine soup to forty patients and others, during a period of three months, came to the conclusions: — 1. That the use of gelatine was both an amelioration and a source of economy in the alimentary system. 2. That gelatine soup is at least as palatable as the ordinary hospital soup ; and, 3. That gelatine is nourishing, easy of digestion, and wholesome, and cannot, in any manner, be productive of injurious effects on the animal economy. The apparatus in the hospital of St. Louis is ca- pable of preparing nine hundred soups per day; it has been in use twenty months, and has supplied 550,800 portions of gelatinous food. Numerous reports have been made on the subject to the ge- neral administration of the hospitals, all of which agree in stating that the change in the mode of nourishment is a decided improve- ment; that the convalescent patients acquire strength much more rapidly than before ; that it is a source of economy highly important to the poor ; that part of the meat formerly employed in making soup may now be given to the patients, either roasted or in other forms, and, finally, they all recommend the adoption of the system of gela- tinous nourishment in all similar establishments. At the Hotel Dieu, 443,650 rations of gelatine have been furnished in fifteen months and a half; and six reports have been marie, all of which are equally favourable with those above referred to. They state particu- larly that since gelatine has been employed, thirty kilogrammes of roast meat may be given to the patients daily, without reducing the quality of the soup at all below its former standard. When M. D' A reel had concluded his remarks, M. Gay Lussac animadverted in strong terms on the injustice and insufficiency of the mode of experiments adopted by M. Donne, which he characterised as wholly inconclusive, although calculated to produce a most injuri- ous effect on the public mind, which is always easily impressed with the idea that the poor are neglected, particularly in hospitals. He reminded the Academy that it was well known that no single sub- stance was alone sufficient to support animal nature ; that animals fed on sugar alone had died from inanition ; yet it would not be pretended that sugar is destitute of nutritive qualities ; and though the nutritive qualities of potatoes, taken with other food, are univer- sally known, a dog fed wholly on that vegetable dies in six weeks ; whereas M. Donne wishes it to be supposed that because two dogs refused to live upon gelatine, administered alone, v\e know not how, and because M. Donne' himself grew thin on a sudden adoption of simple gelatine diet, the adjunction of gelatine, as an ad- dition to, and taken in conjunction with animal feed, is wholly uith- out advantage. On the 20th of June, M. Donne replied to M. Gay Lussac, by haying that his sole object in proposing the question was to have it fully and iairly investigated ; since if it can be established that gelatine does possess the nutritive qualities ascribed to it, the advantage to the poorer classes will be immense; whereas, on the other hand, should they be induced to employ the bones as a means 170 Proceedings of the Royal Academy of Paris. of nutriment, when the fact may turn out to be that the gelatine is not nutritious, their condition is rendered more deplorable than before. In conclusion, he said that he rendered full justice to the active and pure philanthropy of M. D'Arcet, which had induced him to make the greatest sacrifices both of time and money, in order to bring the gelatinous system to perfection. Mirage by Suspensio?i. — On the 20th of June, a letter was read from M. Rozet, stating that he had frequently remarked this atmos- pheric phenomenon in the neighbourhood of Algiers, and particu- larly on the 27th of June, 1830, when about ten o'clock in the morn- ing, at which time the sky was perfectly clear, and the thermometer at 21° (Reaumur), he distinctly saw, when looking at the line of battle formed in the camp at Staonelli, two images of all the objects, the mirage being about half as strongly marked as the real image, but still perfectly distinguishable and elevated above the object about one-fourth of its height, deviating a little laterally. On the Algerine tents, surmounted with tin spheres, with a crescent on the top, the image of a second crescent forming a tangent to the first, was dis- tinctly visible, so that, at first sight, it appeared as if there were two crescents to each tent. When the images are reversed, they are rarely clear, and have always a perceptible movement of undulation. Climate of Algiers. — The same letter stated, that whenever the south wind blows in the neighbourhood of Algiers, the temperature is raised from 5° to 10° C. (41° to 50° F.) On the 17th of September the thermometer stood at 39°(103°F.) in the shade. Those who happened to be affected by drinking at that time, suffered severely, falling down insensible. This wind rarely lasts twenty-four hours, and occasions as much inconvenience to the natives as to the French. Storms are not frequent at Algiers, but when they occur they are of great violence. On the 8th of May last, the whole horizon was a sheet of flame ; a strong white light rested for half an hour on the extremities of the flag-staffs of the forts of Algiers and its vicinity, and the officers, who were walking bareheaded on the terrace, felt their hair stand on end, and perceived a luminous star at the extremity of each ; the same species of star was observed on the ends of the fingers when held upright in the air, but disappeared when held downwards. During these storms every one is affected with great lassitude, parti- cularly in the legs, and experiences strong nervous agitation. New Chart. — At the same meeting M. Coplin presented a topo- graphical chart of the islands of Perouse, in which, by a new plan of drawing, in imitation of relief, he has succeeded in so well availing himself of the process of shading, that not only the geological consti- tution, and the direction of the declivities, but also the variations in the surface of the different mountains are distinctly exhibited to the eye. 171 Miscellaneous Scientific Proceedings on the Continent. ACAD£MIE DES INSCRIPTIONS ET BELLES LETTRES. Indian Antiquities. — On the 22d April, MM. Quatremere, La- jard, and Abel-Remusat, made a report on the antiquarian part of M. Lamare-Picquot's collection of curiosities, brought from Hin- dostan. The zoological part of this splendid collection has formed the subject of a report to the Academic des Sciences (vide p. 157), and the present reporters had, therefore, only to occupy themselves with such parts as tended to throw a light on the civil and religious manners and customs of the Hindoos. The greater part of the articles relating to the Brahmin religion are from Calcutta and its neighbourhood ; those which relate to the worship of Buddha are originally from the Burmese empire, whence they were taken during the war with the English in 1825 ; and a few remarkable curiosities are from the isles of the Ganges. There are about fifty figures representing the divinities of the Brahmins ; these are in terra cotta, marble and bronze, and present images (some of them in bas-relief) of Brahma, Vishnou, Sheva and his wife, Parvati, Krishna and his wife Radha, Gamessa, Balarama or Vishnou as a child, Jagher- nout, Dharma-Deva, or the god of the law, under the figure of an ox ; Dourga the wife of Sheva; Kali, the same goddess with the attributes of goddess of death, those of protectress of the universe, and those of her combat with Mahichaasoura, the genius of evil, under the form of a buffalo. There are also several mythological subjects, executed on pasteboard, by Hindoo painters ; and a large picture represent- ing the combat of Rama against Ravana, the tyrant of the isle of Lauka, a subject taken from the Ramayana or the Baghavata-Pou- rana. M. Lamare-Picquot has also brought over a number of vases, lamps, and other religious and domestic vessels of the Hin- doos. He has also succeeded in procuring three or four Bercho- cath, or pieces of carved wood, representing towers with several stories, enriched with a variety of paintings and ornaments. These are carried in the funeral processions of the Hindoos, and then placed near a pagoda on the banks of the Ganges, or some other consecrated river. The collection also includes a variety of exact models of the Hindoo temples, and a sort of fetish, found in an island of the Ganges, representing a head surmounted by a rudely shaped mitre, and coloured equally coarsely. The reporters have not discovered who is represented by this figure. The figures relating to the worship of Buddha are fewer in number, but of con- siderable dimensions. There are thirty statues of Gaouatama in terra cotta,wood, copper, marble, and alabaster, all exhibiting traces of gilding, and varying in size from one to three feet. This per- sonage is always represented in the act of divination, in a sitting posture at the moment of inspiration, the head surmounted with the characteristic tubercle, the hair in ringlets, half naked, and the right hand pendant. Two only of these statues have inscriptions, one of 172 Miscellaneous Scientific Proceedings which is in Burmese, and the other in Bengalese. Smaller figures in bronze and lead represent other and secondary divinities. One of the rarest pieces is a small group representing eight divinities pre- sent at the birth of a Shakia. There is also a fine and large bas-relief in terra cotta, of Burmese workmanship, which was intended to be placed over the entrance of a temple j it represents two lions, painted red, in an attitude of repose, and separated by stalks of ananas, reminding us of the celebrated religious monuments of Western Asia. The objects not relating to religious ceremonies are figures of different classes of Hindoos in their proper costume; the bodies are in terra cotta, and the dresses in real stuffs ; many of them are executed with great perfection, although the Hindoos of Kishna- gore, by whom they are done, have not practised that kind of work more than fifteen years. There are also a great variety of domestic utensils of the Hindoos calculated to throw great light on their habits and manners. The reporters, in conclusion, bestowed the highest praise on the persevering assiduity of M. Lamare-Picquot, and strongly recommend the formation of an Ethnographic Museum, similar to those existing at St. Petersburgh and various towns of Germany, for the preservation of all the objects of every nation, calculated to throw light on the manners and customs of any nation of the globe. SOCIETE D'ENCOURAGEMENT DES ARTS ET DE L'!NDUSTRIE. Enamel Painting. — On the 1st of June M. Merinnee made a report on a new application of enamel painting, which promises to be of great importance to the arts. This branch of art has hitherto been confined to painting on enamelled metallic plates, or on porce- lain : the objection to the former is that, in consequence of the action of the fire on their shape, they can never be used beyond a certain and small size; while the latter, though presenting the ad- vantage of greater dimensions, has the inconvenience of not being susceptible of being passed above three times through the fire, because the enamel of the porcelain not having the same fusibility as the colours, the latter scale off when the action of the fire is pro- longed beyond a certain point. The difficulty, therefore, was to find a substance which, while, it afforded equal dimensions with the plates of porcelain, would support the action of the fire without breaking or losing its form. This want has been supplied by the discovery of the properties of the lava which is found in great quan- tities in the mountains of Puy-le Dome, and to which the distin- guishing name of tephrine has been given : that procured from Volvie is the best. This lava is very porous, and consequently lighter than common stone. It is sawn into plates of moderate thickness (about half an inch) ; and when these plates have been cut perfectly even, the small cavities of the surface are stopped up with a vitrifiable paste, which, by the action of the fire, forms one substance with the lava, and subsequently unites itself firmly with the layer of enamel which is placed over it. Plates of three and on the Continent. 173 four feet long are thus prepared without much trouble or expense, and they may be made double the size. The blocks sometimes taken from the quarries have a superficies of ten feet square. The enamelled surface of this lava is not even, like the enamel of porce- lain ; but it is a little grained, which renders it particularly adapted for pictures on a large scale, as historical pictures, &c. If it were required to use this substance for miniature painting, the layer of enamel must be perfectly smooth ; and though this would be diffi- cult to effect, the reporter is of opinion that it would not be impos- sible. The Count de Chabrol, when prefect of the Seine, first employed this lava for the trottoirs, or foot-pavements, of the streets ; arid M. Mortelique, being induced from its fusibility, its vitreous qualities, and its porous consistence, to suppose that it was suscep- tible of being enamelled, made a variety of experiments, and ulti- mately, in 1827, exhibited a head, painted the natural size, on a plate of this lava, which was considered worthy of a prize. But in order to render this generally useful, it was requisite to make the enamel painting so nearly analogous to oil painting, that historical painters might acquire the art without material loss of time. The great difference was that, on the enamel, as on porcelain, the colour could only be applied by small touches in juxtaposition, and could only be degraded by letting the white ground appear more or less through the transparent tints. This mode of proceeding, which is that of miniature painters, is much too tedious for artists accustomed to lay the colour thickly on the canvass. M. Montelique has there- fore applied himself to the discovery of a white which will combine itself with all the colours used in enamel painting, without decom- posing them. In this he has fully succeeded, and by this discovery has removed the only difficulty existing in the use of the lava for paintings; so that pictures of the largest size may now be painted in enamel with the same facility as in oil ; and with every facility of retouching the picture, when in progress, is combined the advantage of the colours being rendered capable of bidding defiance to the ravages of time, by the unlimited manner in which they may be passed through the fire. Had this discovery been made three cen- turies earlier, we should not have to deplore the deterioration of the * Last Supper' of Leonardo da Vinci, and the ' Descent from the Cross' of Daniel di Volterra. SOCIETE DE GEOGRAPHIE DE PARIS. Annual Prize. — This prize was proposed for the most important geographical discovery made during the year 1829. The committee, in their report, first mentioned, in terms of praise, Captain King's attempt to explore part of Patagonia, but added, that as his voyage has not yet been published, no judgment can be formed of the impor- tance of the results at which he has arrived. M. Parchappe, by his discoveries in South America, has thrown new light on the course of the Uraguay, and other rivers of the basin of Parana. This traveller, in the twelve years which he has passed in the province of 174 Miscellaneous Scientific Proceedings Buenos Ayres, and those watered by the Parana and Uraguay, has rectified some remarkable errors, particularly that which assigned to the Lake Ibera, from east to west, four times its real length. He has also ascertained, in a satisfactory manner, the course of a part of the rivers Colorado and Negro. The committee also speak favourably of the voyage of circumnavigation of the Russian ships Moller and Seniavin, commanded by Captains Starikowitch and Liitke. The latter, in particular, has discovered new islands in the archipelago of the Carolinas, particularly the island of Pounipet, in- habited by a race of blacks analogous to that which peoples the coast of New Guinea ; whereas all the islands of the archipelago, previously known, are peopled by the copper-coloured race which forms the intermediate link between the Malays and the Polynesians properly so called. The prize, however, (consisting of a gold medal of five hundred francs,) is adjudged to Captain Graah, of the Danish navy, for his exploring voyage along the eastern coast of Greenland, to which he penetrated by sea, and discovered a people who, from a remote age, have been deprived of all communication with Europe, and whose language was nearly unintelligible to the Greenland inter- preters who accompanied him. They retained some vestiges of the Christian religion. The eastern coast of Greenland was previously very little known. Between Cape Farewell 59° 42' latitude, and Cape Barclay 69° lat., very few points were known ; the coast was supposed to proceed in a north-easterly direction, but Captain Graah has ascertained that its direction is nearly north. Greenland was discovered about the year 982, by Eric Rauda, and the Nor- wegians, in the succeeding ages, sent missionaries there, but the colony appears to have entirely dropped into oblivion about the fifteenth century ; and though it was vaguely said that a people differing from the Esquimaux in habits and physiognomy existed somewhere, it was reserved for Captain Graah to ascertain their existence with certainty, and make their situation known to Europe. Captain Graah's Journal will shortly be published, and will probably throw much valuable light on the real direction and position of the toast of Greenland. ACADEMY OF SCIENCES OF ST. PETERSBURGH. Meteorological Phenomena. — On the 9th of February last, a communication was made of a singular phenomenon, observed at Oremburg, on the 1st December. During the whole day a heavy rain fell, although the thermometer remained steady at freezing point : about midnight three loud claps of thunder were heard in a north-westerly direction ; the next day there was a fall of snow, ac- companied by a multitude of little gnats, the motions of which were similar to those of the flea. The day after the atmosphere cleared up, and the thermometer descended ten degrees below zero. At the same meeting a letter from the Governor of Oremburg was read, stating that on the 7th of January, between six and eight in the evening, the moon, which was nearly new, appeared surrounded on the Continent. 175 with a large and perfectly regular luminous circle, cut by two dia- meters equally luminous : the moon occupied the centre of the circle. Two white semicircles were distinctly traced at the extremities of the diameter, which cut the circle from east to west, and their light was reflected almost as far as the extremities of the other diameter which divided the circle with the same regularity from north to south. To the north of this circle was observed aluminous arch of small dimen- sions. During the whole time of this phenomenon being observed, the atmosphere was pure and tranquil, and the thermometer was not below seventeen degrees (Reaumur) ; a short time afterwards it fell to twenty-nine degrees below freezing point. New Mineral. — Tn the month of August last, the Academy wai presented with a new mineral found in some government-lands in the province of Perm. It has received the name of Volkonskdite, in honour of Prince Volkonsky. The spot in which the vein was found is in the mountain called Efimiatskai'a, in the district of Okhausk. The bed does not consist of regular veins, but in bits of from one to four verschocks thick, by a quarter to three-quarters of an archine long ; sometimes ten of those bits or patches are found in the space of a single sagene, and sometimes there are three »agenes without a single one. The mineral, in colour, approaches the grass-green ; it divides in longitudinal plates, and breaks on the slightest pressure. When plunged in water it separates with a loud noise into angular pieces, on which, when dried, the water no longer takes any effect. This mineral may be employed as a colouring matter to replace some of the most expensive colours, such as molo- chite and verdigris. The fine orange colour of chrome may also be chemically obtained from it, as it contains about seven per cent, of extract of chrome. It is easily worked and at a small expense. MlNERALOGICAL SOCIETY OF RUSSIA. Native Emeralds. — A very fine native emerald has lately been given to this society by the Emperor. Its form is a regular hexa- gonal prism ; it is of a beautiful green colour : one of the planes, which usually terminate the extremities of these prisms, remains in its natural state. The other plane, or base of the prism, is covered by a gangue of micaceous schistus similar, as respects its compo- sition and black colour, to that in which emeralds are found at Herbachthal, near Binsgau in Salzburg; but the crystals of the emeralds have never been found there of such large dimensions as those recently discovered in Siberia, of which the above-mentioned is a specimen. This new vein of emeralds in Siberia is situated eighty-five versts to the east of Catherineburg, and was discovered in the following manner. In January last, a peasant of the canton of Belosersk, in looking for stumps of trees to extract resin, found, among the roots of a tree which had been blown down, several frag- ments of emerald which he sold at Catherineburg. This led to further researches, and a most valuable vein has been discovered. 176 FOREIGN AND MISCELLANEOUS INTELLIGENCE. § I.— MECHANICAL SCIENCE. 1. PARABOLIC RIDGES FORMED ON MOVING WATER. M. PONCELET has made some curious observations on the form of the ridges produced when a body is placed in a stream of water flowing with uniform velocity. When a point is placed in the upper surface of water flowing with uniform velocity, a great number of ridges appear of a parabolical form. If a stream of water spout from an orifice in a vessel, these curves have their vertices in a line joining the point and the orifice. The summit of the first parabola is at the point itself, and is the limit of all the others. The number of ridges is indefinite; they are placed at distances which increase with their distance from the point. These ridges become less and less elevated according to their distance from the point, til they vanish altogether. The ridges are perfectly stationary and invariable in their figure, whilst the motion of the fluid remains the same, and they cease to exist the instant the point is removed. If the vein flow in a trough with vertical sides, the same phenomena take place as if it were not so confined; and the ridges are suddenly terminated by the sides without suffering in flexion or reflexion. From these phenomena one might at first sight suppose that the molecules of the current deviate from their natural course and follow the branches of the curve. This, however, is not the case, as may be proved by throwing fine powder on the liquid vein: the particles of the powder cross these ridges, and follow the same course which they would take if the ridges did riot exist, In plunging several points into the vein at different distances, the same system of ridges is obtained for each point, and the curves cross each other at the points where they meet, without their form being in the least altered. When the velocity of the vein is below twenty-five centimetres (ten inches) per second, the ridges be- come imperceptible. They become more and more distinct as the velocity increases. The number of ridges also increase with an in- crease of velocity, the long branches approach more and more to their common axis. The author remarks, that we have here an accurate method of determining the velocity of a current by com- paring the form of the exterior ridge with those given by experiment with a current whose velocity is known. If the point be moved in a straight line along the surface of calm water, we have exactly the same parabolic ridges as we should have with water flowing with the same velocity as the moving point*. * Annales de Chimie, xlvi. p. 5. Mechanical Science. 177 2. NEW THEORY OP CAPILLARY ACTION. M. Poisson has published, as a paper, the first part of a work which will shortly appear, and in which he gives his views of capillary attraction. After viewing what had been done before, he arrives at the conclusion that the phenomena of capillarity are due to molecular action, modified not only by the curvature of the sur- faces, as Laplace has said, but also by the particular state of the liquids at their extremities due to the deficiency on the exterior of that molecular attraction which exists in the interior *. 3. ON THE APPLICABLE FORCE EXERTED BY A HoRSE. M. D'Aubuisson has examined the useful force of a horse by refer- ence to the effects produced at the Freyberg mines, where the ores are raised by this animal power. The horses belong to the neigh- bouring countrypeople, and are occupied for eight hours in the day; they are small for draught horses, but in excellent condition. The power of a horse he distinguishes into useful (or applicable) effect, and dynamic effect : the latter being the total force exerted by the animal, and the former that force minus what is consumed by the resistance and friction of the machine, vis inertia, &c. &c. The useful effect is that which it was his object to estimate, and he found it to equal forty kilogrammes raised one metre (or 2.21bs. raised 39 . 4 inches) in a second ; this being understood of a good ordinary horse working for eight hours, in two portions of four hours each, and in machines of simple construction and properly arranged. From some experiments, &c., of M. Hachette, the dynamic effect would appear to be about sixty kilogrammes raised to the same height in the same time f. 4. BEVAN ON THE RELATIVE HARDNESS OF ROAD MATERIALS. Mr. Bevari has sent to the Philosophical Magazine a table contain- ing the results of experiments made in 1825, principally upon the hardness of road materials, or their power of resisting the per- cussion of a given weight of cast-iron falling a few inches upon the several specimens broken to the ordinary size, and resting upon stone or iron. Supposing the weather to have no action, the table would express nearly the relative value of the materials, for the purpose of supporting the wear of a road; and, therefore, those which resist the action of frost and weather, and have the highest numbers, are most valuable. Mount Sorrel sienite 100 White marble 37. 31 Chert pebble, used much in Mid- 1 04 07 52 56 55 65 • Annales de Chiraie, xlyi, 61. f Annales des Mines, 1830, p. 145. VOL. II. Ava, 1831. N 178 Miscellaneous Intelligence. Quartz pebble in Bedfordshire gravel 70 Ferruginous sandstone of Bedfordshire 20. 42 Hurlock from lower chalk 10 Chalk 3 Granite, Scotch 110 Flint, yellow 33. 26 Greenstone or basalt, Quittle-Hill near Coventry ... 110 Sandstone, soft 13. 6 Tile fragment 20 Gritstone, near Brixworth, Northamptonshire .... 48. 60 Limestone, near Bradwall, Bucks 5 Dry clay 12 Flint, black 11. 30 Portland stone, hard 14 Quartz, white ...» 56 Blue pebble, like Rowley rag 105. 1 10 Coarse limestone, near Stilton, Huntingdonshire .... 60 Gritstone, on road near Leeds 100. 115 Yorkshire paving stone 20 Ketton, hard 20 Tetternhoe 4 Chert? from hills in Devon and Cornwall 57 Gray wether, Hertfordshire and Wiltshire 18 Grit of upper bed, Collymeston, near Stamford, Lin- 1 ^ colnshire J Second bed do 100 Slate at do 50 Stockton limestone, Warwickshire (lias) 45 Newbold, on Avon, do 36 Limestone of Stoke Cruerne, Northamptonshire 35 The steady pressure, without percussion, required to crush a piece of the marble weighing half an ounce, was 100 Ibs ; to crush the grey flint of 1.2 oz. weight, 2000 Ibs. ; to crush the rolled white quartz pebble of 2 oz. weight, 3400 Ibs. * A specimen of the copper slag, recommended for roads by Mr. Fisher of Newgate-street, was sent by Mr. Taylor to Mr. Bevan, to be tried and compared with the above. Mr. Bevan reported upon it, that it was the hardest material he had met with, its num- ber being 234, or above double the highest in the list. The specific gravity was 4.32. A substance of such hardness, not subject to decomposition by exposure to weather, and of moderate price, is considered by Mr. Bevan as a most valuable material for roads of great traffic and heavy loads f. * Vol. is., p. 164. f Phil. Mag., N. S., ix,, 317. Mechanical Science. 179 5. ON THE BUR OF PERFORATIONS. (R. W. Fox, Esq.) If any slender and sharp-pointed instrument (a common needle for instance) be made to revolve quickly whilst piercing a card, it pro- duces an elevation or bur on each side of it. Hence, may it not be inferred that the same effect, caused by an electrical discharge, is due to the rotation of the electrical current or currents ? — for the edges of a hole made by electricity seem to be too regularly and completely elevated on both sides of a card to be reasonably attri- buted to the simple action of opposite currents not in rotation :— * and when several cards are thus perforated together, ought not the outermost cards, on the latter hypothesis, to have "the burs on their inner surfaces, and very little, if any, externally ?— but it is known that the elevations are generally equal on both sides of the cards: so that the simple mechanical fact above stated appears to strengthen the presumption in favour of the rotatory motion of electrical cur- rents. 6. CONDENSATION OP MERCURY BY PRESSURE. It having been deemed very interesting to employ the pressure of the water at great depths for ascertaining the condensation of mer- cury by pressure, the expedition commanded by Captain Kotzebue was furnished with an elaterometer expressly adapted to this pur- pose. It consisted of a wide thermometer tube, open at one end, and having attached to it at the other a bulb like that of a thermo- meter. The tube and bulb were filled with mercury, and a drop of oil poured over it. A scale was attached to the tube, whose divi- sions showed the thousandth parts of the whole volume of the bulb and tube filled with mercury. When the instrument was made to descend to great depths of the ocean, the greatest condensation which the mercury had undergone during the experiment became visible by the oil adhering to the inside of the tube, even after the mercury had returned to its former state of expansion. At the tem- perature of 19° C (66°.2 Fahr.), the mercury stood at the zero point of the scale. Let these degrees be = T, and those at the depth of the sea = t ; the expansion, for one degree of the thermometer, of mercury = m; of glass = w; and the volume of mercury at the tem- perature jT= V : then the contraction of the mercury, on account of the temperature, will be = V, (T—t) (m—ri), which is to be deducted from the whole condensation observed by the instrument. The following experiment was made in 21° 14' north latitude, and 196° 1' west of Greenwich, at the depth of 914.9 toises (5851 Eng- lish feet). At the greatest depth the thermometer was at 2°.44 C., and the elaterometer marked 3°.l. The condensation was, there- fore, 0.0031. Having T= 19 and *=2.44, n = 0.0000274, m = 0.000185, we shall find the contraction of the mercury by N 2 180 Miscellaneous Intelligence. temperature = 0.0026 V, and the compression by the weight of the water is consequently =r 0.0005. Assuming that the condensation is proportional to the pressure, we shall find the compression by the weight of the atmosphere = 0.0000027, which is nearly three times as much as 0.000001, the value assigned by Oersted for this com- pression *. Note. The great condensation of mercury following from this experiment makes it doubtful, in our opinion, whether some of the oil may not have insinuated itself between the glass and the mercury, and it would, perhaps, be desirable to supersede the use of the oil by some other contrivance. 7. INSTRUMENT FOR THE CONDENSATION OP WATER BY THE PRES- SURE EXERTED BY WATER AT GREAT DEPTHS OF THE OCEAN. (Invented by Professor Parrot ofDorpaL) This instrument consists of a hollow glass cylinder terminating below in a hemisphere. The upper end is to be closed by a cover which is screwed on. Through this cover a tube, open at the top, passes, fixed in so tightly as to allow no air or water to pass. This tube, when inserted into the glass cylinder, descends nearly to the bottom, and, after a bend, reascends again nearly to the top, where it ter- minates in a horizontal tapering piece with a small opening at the end. The tube is filled with mercury up to the open point, and the cylinder with water. By a small opening in the cover, which is again closed when the screw of the cover is quite home, the small quantity of superfluous water which may be in the cylinder passes out while the cover is screwing on. It is clear that the pressure of the water in the ocean is exerted on the water in the cylinder entirely through the medium of the mercury in the tube, and that the con- densation of the water is exactly measured by the quantity of mer- cury forced out of the tube through the small opening at its end. The tube is furnished with a scale, on which the proportion which the volume of the mercury wanting in the tube bears to the volume of water in the cylinder is read off f. 8. COMPARISON OF THE PRUSSIAN WEIGHTS AND MEASURES WITH THE NEW ENGLISH WEIGHTS AND MEASURES. (By Professor Eytelwein.) One English inch, at 62° Fahr. = 0.971140 Prussian inch at 61°J Fahr. An English pound avoirdupois, of 7000 grains, = 31.018012 Prussian loth, 32 of which are a Prussian pound. An imperial gallon = 253.95383 Prussian cubic inches J. * Petersburgh Transactions for 1830. f Ibid. Chemical Science. 181 § U.— CHEMICAL SCIENCE. 1. ON THE ELECTRO-MAGNETIC EFFECTS OF METALLIC PLATES HAVING VARIOUS POSITIONS, INTERVALS, &C. &C. (By M. BiglOU.) M. Bigiou has made experiments to determine the relation of electro-magnetic effects, which take place when equal discs of zinc and copper are immersed, under different circumstances, in the same fluid. He obtained the following results: — i. Voltaic electricity is transmitted through a metallic plate, having its surface grooved or roughened with sand-paper, more easily than through a plate of the same metal with a polished surface *. ii. In placing one of the plates inclined to the other, the effect is diminished t- iii- The ex- tent of the surface of copper, as M. Marianini has shown, has a greater influence over the electro-magnetic effect than that of the zinc. The author shows, however, that nothing would be gained in the construction of a voltaic battery, by making the zinc much smaller than the copper, as the greatest effect takes place when they are nearly of the same size. iv. The author remarks that the effect diminishes as the distance between the plates increases J. The most valuable part of his paper, is that in which he gives the relative de- flecting forces of the same plates with different acid solutions. This was ascertained with the torsion galvanometer. Water, with -fa of its bulk of sulph. acid . . 106° of torsion. Do. -j1^ of muriatic acid 58° do. D°' Tiff °f nitric acid • 106° do. Do. -fa of nitric acid, and -fa muriatic acid, 59° do. •D°' ^V °f nitric, and T^ sulphuric acid 96° do. Do. -fa of nitric, and -fa sulphuric acid 120° do. From this it appears, that equal volumes of nitric and sulphuric acids produce the greatest electro-magnetic effects. 2. HARE'S DELICATE GALVANOMETER. Dr. Hare, of Philadelphia, has constructed a galvanometer, with a riband of tin-foil thirty-four feet long, with a slip of paper inter- vening, which he says is more sensitive than those made with cop- per-wire, covered with silk, when the copper-wire was eighty feet long. He finds pure mercury, obtained by precipitating the proto- nitrate by copper, is negative to copper and the other metals, whereas impure mercury is positive, unless the amalgam be formed with the * According to the experiments of Mr. Leslie, the same thing takes place with heat. f This is also the case with radiant heat. J He does not seem to be aware of the law, experimentally proved by Mr. Ritchie, (Journal of the Royal Institution, No. I., page 35,) that the effect diminishes inversely as the square root of the distance oi' the plates. 182 Miscellaneous Intelligence. precious metals. This is a convenient mode of testing the purity of mercury. Dr. Hare observed, that when the poles of the excited galvanic magnet are brought into contact with the mercury, commu- nicating with one pole of the calorimeter, the vertex of the magnet being in contact with the other pole, a gyratory or whirling motion may be observed in the mercury *. The effect is identical with the vortices of Davy, or the rotation of Faraday. 3. POWERFUL ELECTRO-MAGNET. — (By Professor Henry and Dr. Ten Eyck.) In the last number of this Journal, page 609, we gave an account of a powerful electro-magnet, constructed in America, by Professor Henry and Dr. Ten Eyck, which was capable of sustaining about 750 Ibs. These gentlemen have carried their researches still further, and have actually constructed an electro-magnet for Yale College, which is said to have sustained 2063 Ibs., or nearly a ton ! It was constructed on the same principle as the former, but a greater number of strands of copper wire were employed. ' The magnet is wound with 26 strands of copper bell-wire, covered with cotton thread, 31 feet long; about 18 inches of the ends are left project- ing, so that only 28 feet of each actually surround the iron ; the aggregate length of the coils is, therefore, 728 feet. Each strand is wound on a little less than an inch ; in the middle of the horseshoe it forms three thicknesses of wire, and on the ends or near the poles, it is wound so as to form six thicknesses.' With a battery of 4-J square feet, the magnet suspended 2063 Ibs. The effects of a larger battery were not tried. It induced magnetism in a piece of soft iron, so energetically, as to raise 155 Ibs. When two batteries were employed so that the poles could be rapidly reversed, a curious fact was observed. After one of the batteries had been removed, the armature, with a weight added, in all 89 Ibs., remained sus- pended, and did not fall when the poles were reversed. This effect must have been instantaneous, otherwise the weight must have fallen, as there was an instant when the magnet could have had no power. It was attempted to decompose water by this magnet, but without success |- 4. ON ELECTRICITY INDUCED BY THE RED AND VIOLET RAYS OP THE SOLAR SPECTRUM. Professor Saverio Barlocci, of Rome, states that when two pieces of copper, painted black, and one of them connected with the upper part of a frog, and the other with the hind feet, are placed one of them in the red, and the other in the violet ray of the solar spectrum, and then * Sillnnan's Journal, xx., page 143. f Id. xx., page 201. Chemical Science. 183 brought into contact, that contractions took place in the muscles of the frog*. 5. ON THE IDENTITY OF THE NERVOUS AND ELECTRIC FLUIDS. The following experiment is from an inaugural thesis by Dr. David, of Paris: — * The sciatic nerve of a rabbit was insulated and laid bare, and carefully sponged ; a piece of glass was gently introduced between the nerves and the muscles, while the leg of the animal was bent. The sensibility of the nerve was shown by the motions of the animal during the introduction of the needles, the one above the other, but not touching each other. They were placed in com- munication with the galvanometer : the animal was quite tranquil, and the needle of the instrument at rest. By a sudden movement of the rabbit, the apparatus was deranged, but the needle clearly deviated and moved. The needles were again introduced ; some muscular contraction succeeded, again the needle oscillated, but so slightly, as not to convince the assistants. The animal, however, soon made some very vigorous and repeated exertions, and there was no longer any doubt of the fact, for the needle now described an arc of more than two lines. The oscillations ceased with the motions of the animal, and again appeared when it moved. The animal was excited to make contractile efforts, by stimulating the nostrils or irritating the nerve, and the needle immediately oscillated, and the arc it described was great in proportion to the energy of the muscular exertions which were provoked. The phenomena could, in fact, be caused at will. With four needles, double the effect could be produced than when two only were employed. In general, the intensity of the phenomena diminished with the vigour of the animal, and they were not observable after death. When two needles were placed in a nerve, and two in a muscle, the oscillations were barely perceptible ; when all four were introduced into a muscle, M . David could obtain no deviation of the galvanometric needle. Other experiments demonstrated why sometimes the phenomena may not arise when needles were placed in a nerve. The causes of the non-occurrence of the phenomena may be either, i. Insensibi- lity of the nerve, from its being strained or pressed upon in spong- ing it. ii. Its too great tension over the glass placed beneath, iii. Blood may cover both the nerve and needles, iv. The per- fect dryness of the nerve, produced by the sponge. It is then necessary to place the nerve for a moment in contact with the muscles, and its power is restored. It is highly important that the needles and the extremities of the threads of the galvanometer should be perfectly clean. M. David considers these experiments sufficient, i. To prove that organized beings have a special apparatus, which is destined to Journal des Progres des Sciences et Med., torn, ii., 1830 184 Miscellaneous Intelligence. furnish an electric current; and ii. To show the circumstances which are required for its production *. 6. SINGULAR ELECTRICAL EFFECT. 4 Whilst the workmen were soldering the iron water pipes in Water Street/ says the Winchester Republican, * electric shocks were pro- duced to such a degree as to cause them to discontinue their labour for the remainder of the day. Several of our citizens who were standing by, got into the ditch and tried the experiment, when the effect was the same on all. The pipes are united in the following manner : — They are nine feet long, perfect cylinders, with a bore of six inches, and a bowl at one end four inches deep ; at the spring is a funnel pipe, which is inserted into the bowl of the succeeding pipe, the spigot end of which is inserted into the bowl of the next, and so on. When fifty or a hundred pipes are laid down in this manner the process of soldering commences. This is done by first ramming into the joint a few strands of rope yarn, and then applying clay around the joint, leaving an aperture at the top into which the molten lead is poured ; the clay is then taken off, and the lead driven home with a blunt chisel and hammer. It was in driving home the lead that the shocks were produced. The sun was nearly vertical, and the thermometer at 93°, the ditch somewhat damp, and the pipes warm from the action of the sun upon them. The principle is no doubt that of galvanism ; but as the cause is sup- posed to be entirely new, the plumber (Mr. Johnson, from Phila- delphia) having never known anything like it during his long expe- rience in that city, we should be glad to receive the opinion of scientific men upon it. We have since been informed, that after a heavy rain on the ensuing day, and the covering of a few feet of the pipes some distance above with earth, the phenomenon did not occur, nor has it since occurred.' A correspondent in Sillimarfs Journal considers the effect as no doubt thermo-electric, and Professor Silliman agrees with him. The voltaic series of iron and lead is supposed to be rendered active by the intense heat of the sun, the black colour of the pipes causing them to rise to a higher degree than the neighbouring atmosphere, and the pipes being themselves unequally acted upon, from lying in a ditch f. 7. EXPLOSION OF PHOSPHORUS AND NITRIC ACID. Dr. Hare had prepared some very strong nitric acid (having used above one half more of sulphuric acid than the equivalent propor- tion), which had a specific gravity above 1.5, and used it to illus- trate the action upon phosphorus. A tube about seven-eighths of an inch in diameter, closed at one end, was placed within a stout * Med. Phys. Journ., 1831, 454. | Silliman's Journal, xvii. 194. Chemical Science. 185 hollow glass cylinder of about three inches diameter, of which the glass was nearly three-eighths of an inch thick. The whole was situated about four feet in the rear of the table. About five grains of phosphorus, in two or three lumps, was thrown into about as much of the acid as occupied the tube an inch and a half in height. Very soon afterwards, there was a flash, followed by an explosion like that of gunpowder, and the fragments of the glass cylinder, as well as of the tube, were driven in all directions, so as to break many glass articles at the distance of from five to twenty feet, and to wound slightly some of the spectators. On repeating the experiment on a smaller scale with the same acid, similar effects took place, so that Dr. Hare thinks it necessary to strengthen the ordinary precautions given relative to this action, since it may occasionally rise to such intensity as has just been described. Professor Silliman adds some statements and remarks, and says, that if the acid be very strong, and especially if warm, the phospho- rus burns with a splendid combustion ; it is thrown about in jets of fire, and requires great caution. To render it the most beautiful, a tall, narrow, deep vessel should be used, but when the quantity of both substances is considerable, there is sometimes a dangerous explosion. * This circumstance has happened so often in my own experience with nitric acid distilled from very pure nitre, and with- out any water in the receiver, that I cannot but repeat the caution, that the operator should be much on his guard. With a stick of phosphorus dropped into two or three ounces of strong nitrous acid, I have known an explosion like that of a swivel, and the frag- ments of glass wounded persons at a distance, although the experi- ment was performed out of doors, and the spectators, formed into a ring, were none of them nearer than fifty feet, and some who were hit were at double that distance*. 8. ON THE PHOSPHORESCENCE OF CERTAIN SUBSTANCES. From the result of numerous experiments made by M. Saladin, he has been induced to conclude that the phosphorescence of many bodies, as dried bones, rotten wood, &c., was caused by the presence of a small proportion of phosphorus evolved by the action of organic matter on the phosphates present, and combining with hydrogen in the nascent state. This action is compared to that upon sulphates in similar circumstances, and has led M. Saladin to several conclu- sions, and particularly to that which implies that phosphorescence (except in the case of certain insects) diminishes with the proportion of phosphates. Experiments are still wanting to prove this point ; but whilst engaged in performing them, M. Saladin is still anxious to secure the credit of priority in taking this view of the effectf. * Silliman's Journal, xvi. 366. f Jpurn. de Pharmacie, 1831, 212. 186 Miscellaneous Intelligence. r9. ON OXALIC ACID. — (By M. Gay Lussac.) Oxalic acid, when heated, is well known to be partly volatilized and partly decomposed into carbonic acid and a combustible gas. Wishing to know more particularly the nature of these gases, M. Gay Lussac heated some very pure crystals of the acid in a retort: at 209° F. they fused ; at 230° water and elastic fluids were disen- gaged, and the latter increased as the water passed away ; at 248° — 266° the disengagement was very rapid, and continued until all the acid was decomposed*. The gas was a mixture of six volumes of carbonic acid and five volumes of carbonic oxide, the proportion being nearly the same during the whole decomposition. This easy decomposition was unexpected ; for oxalic acid is con- sidered as a stable compound among vegetable acids. The utility of sulphuric acid in the ordinary mode of decomposition was there- fore suspected, and it was found, in fact, that when mixed with that acid, still a temperature of 230° — 240° was required. But there is this important difference, that in the latter case the gas evolved consists of equal volumes of carbonic acid and carbonic oxide. This difference led to the suspicion that some other substance was formed during the decomposition. On examination, it was found that the water which passed over was acid, and that it was so from the presence of formic acid. At first this acid appears in small quantity, but it comes over more and more concentrated, and towards the end of the operation the product has a very penetrating odour and sharp taste. Supposing that the sixth or missing vo- lume of carbonic oxide with water forms this acid, then twelve pro- portions of oxalic acid should form one of formic acid, and this ap- peared to be the case. It is evident that the hydrogen has been given to the formic acid by the water, and not by the oxalic acid, for then the carbonic acid and oxide should have been in equal volumes ; besides, it is a necessary consequence of the experiments of MM. Dulong and Dobereiner. If the decomposition is not carried on too rapidly, it is total, no oxalic acid being volatilized. These effects render it more imperative, M. Gay Lussac thinks, that oxalic acid should not be separated from the two other com- pounds of carbon and oxygen, i. e. carbonic acid and carbonic oxide, It may be ranged amongst those acids into which two equivalents of the radical enter, and the name which may be applied to it is hypocarbonic acid ; but M. Gay Lussac does not press the adoption of this name at present f. 10. Dr. TURNER ON THE VOLATILITY OF OXALIC ACID. Dr. Turner having lately examined the volatility of oxalic acid, finds * See next page. f Annales de Chimie, xlvi. 218. Chemical Science. 187 the substance to rise at temperature so low as 212°,* without un- dergoing any chemical change, except that the common crystals lose two-thirds or two equivalents of their water of crystallization. If ordinary oxalic acid be placed in a water bath, and heated, it efflo- resces, losing nearly the proportion of water mentioned ; if exposed to the cold air, it recovers the water ; but if continued hot, it sub- limes, and minute acicular crystals form on the surface. If purified oxalic acid in crystals be exposed to 350° or 400°, in a deep evapo- rating basin, and, when sublimation begins, the vessel be covered by a layer of smooth filtering paper, a fold of blotting paper, and a larger evaporating basin containing cold water, the oxalic acid con- denses in crystals on the filtering paper, or falls on the side of the dish, and after an hour may be removed, and quickly secured in a stoppered bottle. Thus sublimed, the acid is in minute shining acicular crystals, which, on exposure to air, become dull, and regain the two equivalents of water. At higher temperatures the sublimation proceeds more rapidly. At 300° or 330°, none is decomposed f. At 360° or 400°, the subli- mation is very free ; at 414° it fuses, and boils freely ; above 330°, decomposition to a greater or smaller extent occurs, and is indicated by the appearance of water. By combining the sublimed acid with bases, &c. &c., its unchanged nature was ascertained. Dr. Turner found that a saturated solution of oxalic acid at the temperature of 50°, contained 1 part crystallized acid, and 15.5 parts water. At 57°, 9.5 parts of water dissolved 1 part of crystal- lized acid. At 212°, the quantity of acid dissolved is almost unli- mited ; at 220° the crystals fuse in the water of crystallization }. 11. SCINTILLATION OF STEEL. INFLAMMATION OF GUNPOWDER. You inquire if we have ever tried whether gunpowder will fire in the sparks from our polishing wheels §. We have tried the experi- ment, and find that when coarse emery is used on the wheels it will be fired at any distance to which the sparks extend ; but when very fine emery is used, a stream of innumerable sparks may be poured upon coarse gunpowder without inflaming it. The same powder, however, on being finely pulverized, will be readily inflamed by the sparks from the fire wheel. In both cases, the sparks are particles of ignited iron, and there can be no difference in the two cases, * It sublimes at common temperatures. See pp. 73, 74, of the last volume of this Journal. •f* See preceding page. J Phil. Mag., N. S. Jx. 161. § The polishing wheels referred to are of various sizes and kinds, from large grindstones, on which the gun-barrels are ground, to small wheels covered with oiled leather and armed with emery powder. All these wheels are moved with great rapidity by strong water power, and when the steel articles are held upon them, there is a splendid coruscation of innumerable sparks flying off in tangent lines, which follow oue another with such rapidity, that the wheel is constantly surrounded with a glory. 188 Miscellaneous Intelligence. except in the magnitude of the particles. It would seem, therefore, that within certain limits gunpowder will not be inflamed by par- ticles of ignited iron, unless they have at least a certain magnitude in relation to the magnitude of the grains of the powder. Your question was probably suggested by the fact, well known to you, that on putting the hand into the stream of sparks, the sensation experienced is rather that of cold than of heat. This is a fact which not a little surprizes those of our numerous visitors who have the courage to present their hands to a stream of fire so dense as to have the appearance of one continued flame. The paradox, I appre- hend, may be explained in the following manner. The particles which make up the stream are much smaller in dimen- sions and fewer in number than they appear to be, each particle, from the extreme rapidity of its motion, appearing to extend several inches, when, in fact, it is little more than a mere point. These particles, being thus minute, do not impart a sufficient quantity of heat to penetrate through the insensible external membrane of the skin, called the cuticle or epidermis, so as to reach the adjacent mem- brane which alone is the organ of sensation, before it is again withdrawn by the increase of evaporation produced by the current of air which the wheel puts in motion. If the hand is held steadily in the stream until the evaporation is diminished by the gradual desiccation of the skin, we shall perceive a mild sensation of heat. These sensations, first of cold only, and afterwards of mild heat, take place only when we present to the stream the inside of the hand or fingers, where the cuticle is thick. If the back of the hand be presented, a very pungent and pricking sensation of heat is pro- duced at every point where a particle impinges, highly contrasted, at the same time, with a general sensation of cold, produced by the increased evaporation. In the first case, the heat is passing through the thick cuticle of the inside of the hand, extends laterally, and loses its intensity before it reaches the sensible membrane ; but the cuticle on the back of the hand being extremely thin is immediately penetrated *. 12. NEW PYROPHORUS. Dr. Hare recommends as a new pyrophorus, Prussian blue heated to redness, for about a minute, in a glass tube, and then sealed up hermetically. As soon as the tube is fractured, and the contents thrown out upon a table, they take fire t. 13. CRYSTALLIZATION OF OXIDES OF IRON AND ZINC. (By M. Haldat.) M. Haldat is in the habit of using a bundle of soft iron wire in his demonstration of the action of steam at high temperatures on iron, * Silliman's Jouin., xvii. p. 114. f Ibid.,xix. 173. Chemical Science. 189 and by management has obtained larger crystals of oxide of iron than are usually procured. These crystals are finer the longer the action of the iron and steam has been continued ; they have occa- sionally been obtained one-tenth of an inch in size upon large wire or plates of iron. The crystals are very brilliant, and, under the microscope, perfectly resemble those from Elba or Framont. They are usually rhomboids, covering each other as in the iron ores from those countries, have the same brilliancy and colours, and every other character except size. M. Haldat then endeavoured to obtain crystallized oxide of zinc by similar means ; and by using precautions relative to the applica- tion of heat, rendered necessary by the greater fusibility of zinc, succeeded in his object. The oxide had two forms, being sometimes in amorphous globules, and at others in plates covered with rhom- boidal transparent crystals, having the colour of honey. As in volcanoes, most of the circumstances meet necessarily in these experiments to produce crystals, it is probable that all the vari- eties of crystallized oxide of iron there found, result from a process analogous to the present *. Mr. Daniell obtained very fine octohedral crystals of oxide of iron upon the bars of iron, used in his pyrometrical experiments, and which had been heated with very imperfect access of air f. 14. DISCOVERY OP VANADIUM IN SCOTLAND. Mr. James F. W. Johnston has discovered Vanadium in Scotland, in a mineral from Wanlockhead, resembling in appearance an ar- seniate of lead ; and it is a remarkable circumstance, that this new substance has been discovered by three different persons — Professor Del Rio, Professor Sefstrom, and Mr. Johnston — in three different countries, Mexico, Sweden, and Scotland, nearly at the same time, and without any knowledge, on the part of one, of what the others had done. Mr. Johnston discovered it during the last winter in two minerals, very different in character, but both compounds of lead, probably Vanadiates. The first resembles an arseniate, occurs in small mamillae upon the surface of calamine, sometimes passing into a crystalline form. The second mineral can hardly be distinguished from earthy porous peroxide of manganese. It occurs amorphous and in small rounded forms, often powdering the calamine with a thin black coating, and at times scattered in cavities J. 15. YELLOW DYE FROM SULPHURET OF CADMIUM. M. Lassaigne proposes to use this substance as a yellow dye on silk. If the silk be immersed in a solution of chloride of cadmium for fif- * Annales de Chimie, xlv. 70. f Phil. Transactions. ; Brewster's Journal, v. 167. 190 Miscellaneous Intelligence. teen or twenty minutes, at temperatures between 122° and 140° F., then wrung out and immersed at common temperatures, in a weak solution of hydrosulphuret of potassa, it becomes of a fine gold yellow colour, or of lighter or deeper tints, according to the strength of the cadmium solution. This dye is unaltered by sun-light, or weak acid, or alkaline solutions. Wool could not be dyed by means of this substance with the same facility as silk*. 16. SEPARATION OF ANTIMONY AND TIN. The separation of these metals is very difficult, because of the simi- larity existing between them. M . Gay Lussac has for this purpose long successfully used tin as a precipitant of the antimony. The two metals, their weight being known, are supposed to be in solu- tion in muriatic acid. If alloyed, they would be dissolved in muri- atic acid to which small quantities of nitric acid had been succes- sively added. A plate of tin is to be immersed ; and there being muriatic acid in excess, the antimony will soon deposit as a black powder. The effect will not be perfect at common temperatures ; but by applying the heat of a vapour-bath, it will quickly be con- cluded, provided that excess of acid is continued in the liquor. The antimony is then to be well washed and dried on the water-bath. If the two metals are in solution, their weight not being known, one portion should be precipitated by zinc, to give the whole of both metals, and another portion by tin, to give the proportion of antimonyf. 17. COMPOUND OF BI-CYANIDE OF MERCURY AND IODIDE OF POTAS- SIUM. {By Dr. Apjohn.) When solutions of iodide of potassium and bi-cyanide of mercury are mingled and left, a beautiful pearly substance, in very thin four- sided prisms, is formed, very soluble in hot water, but scarcely affected by water at 60°. These undergo no change by ammonia, potash, or the carbonated alkalies in solution : muriatic acid renders them bright scarlet, and evolves the odour of prussic acid. When ignited in a crucible, the residue gave an abundant precipitate with tartaric acid. These and other experiments proved that the com- pound contained both the salts added in solution, and upon analysis they were found in the following proportions : — Bi-cyanide of mercury . . 24.16 Iodide of potassium . . . 15.47 And as these numbers are very nearly in the ratio of the equivalent numbers, it appears that a proportional of each proximate element is present. That the substances are not present, as bi-prussiate and hydriodate, is shown by the correspondence of the absolute weights with the estimate above given, and by the fact that, when * Annales de Chimie, adv., 433. f Ibid., advi., 222. Chemical Science. 191 heated in a tube, no water is evolved. Dr. Apjohn proposes to call the substance iodo-bicyanide of potassium and mercury*. 18. COMPOSITION OP TARTARIC ACID. By differences between his own estimate and that of Prout, Berze- lius has been induced to re-examine the composition and number of tartaric acid. He finds, from many experiments, that the tartrate of lead is composed of Tartaric acid .... 37.2569 Oxide of lead . . . .62.7431 Its atomic weight, therefore, is 828.05; hydrogen being 12.5, and oxide of lead 1394.5. Tartaric acid is composed of Hydrogen 3.0045 Carbon 36.8060 Oxygen 60.1895 100 which agrees with 5 atoms oxygen, 4 carbon, and 4 hydrogen (on the assumption that water contains 2 atoms of hydrogen). Calcu- lated in this way, the atomic weight should be 830.709, instead of 828.05, as above. Prout made it 830.709 by his analysis. Berzelius then examined the equivalent number of lead and its oxide very rigorously ; and for this purpose prepared an extremely pure oxide of lead, and reduced it by hydrogen at a sufficiently high temperature. From the mean of six experiments, the results were, per cent. — Lead 92.8277 Oxygen 7.1723 And the atomic weight of lead 1294.29, instead of 1394.5, as above ; hydrogen being 12.5. All the six results were between 1293 and 1296. 4 But if the atom of hydrogen weighs 12.5, the atomic weight of lead, to be a multiple of that number, should be either 1287 . 5 or 1300 ; and if one of these numbers is the true one, my results ought to oscillate about it, instead of oscillating, as actually happened, between 1293 and 1296.' Other considerations, drawn from the analysis of the tartrate of lead, are by M. Berzelius considered as opposed to the theory of multiple numbers of hydrogen f. 19. RACEMIC ACID OR PARA-TARTARIC ACID. The following account of this acid is abstracted from Berzelius. A manufacturer of tartaric acid at Thann, on the Upper Rhine, first observed that with the ordinary acid appeared crystals of another * Phil. Mag., N.S., is-, 401. f Annales de Chimie, xlvi. 192 Miscellaneous Intelligence. and less soluble acid. He mistook it for, and sold it as, oxalic acid. In 1819, Jahn described it in his Dictionary of Chemistry, and distinguished it from both tartaric and oxalic acid. In 1826, Gay Lussac showed that it was not tartaric acid, though its equivalent number was almost the same. Some time after, Walchner also ex- perimented on this acid. The acid is supposed to be peculiar to the grape of the Upper Rhine ; but is probably present in all grapes. It may be obtained by exactly saturating tartar containing racemic acid, with carbonate of soda, and crystallizing most of the double salt formed. The tartrate separates first, the far more soluble racemate remaining dissolved ; when it crystallizes, its forms are different to those of the tartrate. The mother liquor is to be evaporated, precipitated by a salt of lead or lime ; and the separated precipitate decomposed by sulphuric acid. Racemic acid first precipitates in crystals from the acid solution, and then tartaric acid. Racemic acid requires 5 parts of water for its solution ; tartaric acid only 2 parts. The equivalent number was deduced from the racemate of lead. This compound is much more soluble in excess of acid than tartrate of lead, and usually covers the sides of the glass with a thin crystal- line crust. The precipitated salt does not contain water, but the crystallized salt does. The results of analysis were exactly the same, both for the atomic proportion and the ultimate composition, as for tartaric acid, (for which see the preceding page ;) so that this substance furnishes a new example of the extraordinary fact, that bodies composed of the same number of simple atoms may, never- theless, possess different properties. Racemic acid has a different crystalline form from tartaric acid, and also effloresces by heat, which tartaric acid does not. Pulverised racemic acid, exposed to dry air at 64° F., for twenty-four hours, was then dried in a current of air at 212° F., and lost 10.63 per cent, of water. This loss did not increase, and it was found neces- sary to use oxide of lead as a base, and apply heat above 212°, before all the water was expelled. The loss ultimately amounted to 21.35 per cent., or two proportions of water. Of these, one may be disengaged by heat alone, and the other by heat and a base. As tartaric acid also contains two proportions of water, the differ- ence in the characters of the crystals is not due to that substance. With potash, an acid racemate may be formed equally insoluble with cream of tartar, and containing, like it, an atom of water of crystallization. The crystals appeared to differ in form from those of cream of tartar. The racemate of potash and soda, if it exist at all, does not resemble Rochelle salts : a confused mass only is left, and it is uncertain whether it is a double salt or a mixture of salts. A racemate of potash and antimony may be formed analogous to tartar emetic, but its crystals differ, being sometimes rhomboids, sometimes rhomboidal prisms. As two tartrates of potassa and antimony can be formed, one crystallizable, the other not, so also Chemical Science. 193 (wo similar racemates exist, but both are crystalline, the second occurring in acicular crystals, which in sunshine become as white as milk. The same change happens to the corresponding gummy tar- trate, in which also minute crystals may occasionally be seen. The racemate of lime is much less soluble than the tartrate ; both have the same composition, and both contain 4 atoms of water in combination. The tartrate contains 21.765 per cent, of lime, and the dried racemate gave 21.775 per cent, of lime. A solution of sulphate of lime in water is decomposed by the addition of a little racemic acid ; and after twenty-four hours, most of the lime is found precipitated as racemate of lime. Tartaric acid does not do this. If two solutions be prepared in muriatic acid, a little diluted, — one of racemate of lime, and the other of tartrate — and then each be saturated with ammonia, the racemate quickly falls as a semi-crys- talline, white, opaque powder ; but the tartrate does not, unless the liquid be much concentrated. After some time, octohedral crystals form upon the glass. This is a good method of distinguishing the acid, when one* of them is in solution. A solution of racemate of lime, evaporated spontaneously, yields crystallized racemic acid ; but evaporated by heat, the muriatic acid is volatilized, and the addition of water dissolves no racemate*. 20. ON GALLIC ACID. — (By M. Braconnot.) M. Braconnot had recommended the preparation of gallic acid by a process in which the tannin present in the infusion of galls was removed by gelatine ; but M. Berzelius thought that such gallic acid was chemically combined with tannin, and that pure gallic acid could be obtained only by sublimation. M. Braconnot has there- fore made further experiments, and finds that the two substances differ, and that, not from the presence of tannin in the unsublimed acid. The latter he calls pure gallic acid, and the other pyrogallic acid. When very white gallic acid, giving no indication of tannin to gelatine, was moderately heated, it became a brown liquid, which crystallized on cooling, and which, dissolved in water, contained still gallic acid and a brown substance which precipitated gelatine abun- dantly. Thirty parts of dry white gallic acid, being subjected to a higher heat, gave only 3J parts of sublimed gallic acid : though very white, its solution precipitated gelatine. The residue, when dissolved, gave a brown liquor, which became much deeper with persulphate of iron, and blue-black with protosulphate (these being characters of pyrogallic acid, and not of gallic acid) ; and it also abundantly precipitated gelatine. Hence, heat appears to rearrange the elements of gallic acid, so as to produce a peculiar variety of tannin and pyro-gallic acid. Pyrogallic acid reddens litmus paper, though less than gallic acid ; * Aonales de Chiinie, xlvi., 128. VOL. II. Aua. 1831. O 194 Miscellaneous Intelligence. it has a cool, bitter taste. It dissolves in 2J parts of water, at 55° F., whilst gallic acid requires 100 parts at the same temperature. When re-sublimed, pyrogallic acid is decomposed almost entirely, producing tannin and charcoal. It dissolves in ether. Its aqueous solution is colourless, but by exposure to air becomes coloured, and deposits ulmin, being entirely decomposed in a few days if water be added as evaporation proceeds. Persulphate of iron added to it is immediately reduced to protosulphate, and a tanning matter is formed. Protosulphate of iron produces a blue-black liquor. These actions are very different from those of gallic acid, which with proto- salts of iron produce no change, and with persalts produce a fine blue colour. Pyrogallic fccid slightly heated with strong sulphuric acid does not become coloured, and is not sensibly decomposed. Pure gallic acid treated in a similar way became coloured, but on adding water was found not much altered ; no tannin was produced. Strong sul- phuric acid and a higher temperature converted the gallic acid into ulmin ; no tannin was formed. Pyrogallate of alumina forms a bitter solution, becoming turbid by heat, and transparent when cold ; it powerfully coagulates gela- tine ; crystallizes ; and reddens litmus paper more powerfujly than the acid alone ; as if alumine itself acted as an acid. Every endeavour to form gallic acid (upon Berzelius' views), by combining pyrogallic acid and tannin, failed. From all these facts, M. Braconnot concludes, i. That gallic acid procured in the humid way, and cleansed by animal charcoal, is pure ; ii. That heat con- verts it into tannin and pyrogallic acid ; iii. That gallic acid cannot be produced from tannin and pyrogallic acid *. 21. SuLPHO-SlNAPISINE, OR SULPHO-SlNAPIC ACID. MM. Henry and Garot described some years since a curious product derived from white mustard-seed (sinapis alba), which they called sulpho-sinapic acid, to point out at once its source, the presence of sulphur in it, and its acid nature. Some discussion has arisen relative to the subject, M. Pelouze having denied the existence of this acid, and referred the properties observed to the presence of sulpho-cyanic acid or its compounds. This has drawn forth a memoir from the discoverers and from others, in which many curious points relative to this body are established. We do not in- tend to enter into the controversy, but wish to give an account of the points really established, or, at least, most recently ascertained. The following account is from MM. Henry and Garot's second memoir. Sulpho-sinapisine is prepared by boiling the coarse powder of white mustard-seed, or of the turrites glabra, for a minute, with five or six times its weight of distilled water, in a copper vessel, the liquid passed through a cloth, and the solid portion pressed. The magma, when exposed to the air, evolves a sulphurous smell. The * Annales de Chimie, xlvi., 206. .Chemical Science. 195 yellow tinted liquid is slightly acid ; it is to be quickly evaporated in a tin vessel by a water-bath, until like honey, when it will appear as a yellow, bitterish mass, having an odour like that of osmazome. Six or eight times its weight of strong alcohol is immediately to be added, and a tincture will be obtained yellow, slightly acid, and pro- ducing a strong red colour with persalts of iron. This tincture being distilled, the product has no power of affecting persalts of iron. The red-brown, syrupy, transparent matter left in the retort, crystallizes by slow cooling, or becomes a granulated mass if agitated: being allowed to drain on a cloth, then pressed, then puri- fied two or three times in very strong alcohol, its bulk increases much, and it ultimately appears as a white crystalline substance, and is sulpho-sinapisine. Further portions may be obtained by evaporat- ing the mother liquor : the crystalline masses obtained require to be digested in ether to separate a volatile red body soluble in that fluid. Sulpho-sinapisine is white, inodorous, bitter, very light, soluble in water and alcohol, and more so when hot than when cold. When hot saturated solutions are cooled, acicular crystals in rounded groupes are produced ; they]are most distinctly formed in acidulated water. When heated, it fuses, and is decomposed, yielding fetid products, amongst which are carbonate and hydro-sulphuret of ammonia. The substance is not naturally acid, but yields an acid by various modes of treatment. Being analysed, its ultimate composition appeared to be per cent. Carbon 50.504 or by theory 50.504 Hydrogen . . 7.795 7.795 Nitrogen... 4.940 5.020 Sulphur 9.657 9.657 Oxygen.... 27.104 27.024 As the nitrogen and sulphur are nearly in the proportions belonging to sulpho-cyanogen, we may consider sulpho-sinapisine as represented by sulpho-cyanogen, and an organic matter not azoted, which may perhaps be competent to form the volatile oil of mustard. Sulpho-Sinapisine, with nitric acid, is instantly altered ; a bright red colour is produced, much orange-coloured gas formed, and sul- phuric acid appears. With muriatic acid it is dissolved, and be- comes green ; heat then produces a strong odour of prussic acid. Distilled with sulphuric or phosphoric acid, sulpho-cyanic acid is obtained, and, with the first, sulphuretted hydrogen also. With chlorine, prussic acid and sulphuric acid were formed. When treated with alkalies the following were the principal results. Ammonia dissolved it, but effected little change. Potassa and soda, with a little water, changed the colour to red and green ; being evaporated and dried, much volatile oil of mustard rose. Then the substance fused > and was found to be sulpho-cyanide of potassium; further heat destroyed this state of things, leaving 196 Miscellaneous Intelligence. charcoal and sulphates. Lime and baryta produced similar effect, for heat enabled the mixture to produce volatile oil of mustard and sulpho-cyanogen. As to the action of salts, persalts of iron are strongly reddened by sulpho-sinapisine. The persulphate of copper is precipitated white ; the proto-nitrate of mercury is precipitated white ; the acid nitrate of silver is precipitated as a dense white substance, the weight of which, as sulpho-cyanide, is equivalent nearly to the sulpho-cyanogen which the substance could form. From all these circumstances it appears that sulpho-sinapisine is a curious body, not acid, containing sul- phur, and containing no sulpho-cyanogen, but competent to form it by various modes of treatment *. In an after Number t is a highly interesting memoir on the same subject by MM. Boutron and Robiquet. Suspecting that, in con- sequence of the presence of water, certain substances were formed during the process of extraction, which did not pre-exist in the mus- tard-seed, they devised various processes dependent upon the action of ether and strong alcohol, (and which involved much trouble) to obtain the substances in the seed in a state as near their original condition as possible, gathering up as they proceeded numerous ob- servations on the changes, &c. &c. of the substances during the suc- cessive actions. By the action of ether, in the first place, they dis- covered an acrid fixed principle, which had not before been observed. On carrying on the operations they obtained the substance cor- responding to the sulpho-sinapisine already described; but it had a very different composition to that given. In the following columns, the second gives the proportions of the new sulpho-sinapisine, the third that of the substance before described, the numbers being corrected by M. Pelouze. Carbon 54.0000 ... 57.920 Hydrogen 10.6512 . . . 7.795 Nitrogen 2.8392 . . . 4.940 Sulphur 9.3670 ... 9.657 Oxygen 23.1426 . . . 19.688 From these and other anomalies they conclude that it is impos- sible to state any thing correctly respecting the true nature of organic substances, and also that we cannot be certain of their pre- existence, until they have been obtained identical in their nature by several different processes. On mixing black mustard powder with its weight of pure water, or with water containing a little acetic or sulphuric acid, or sub-car- bonate of potassa, the two first mixtures evolved their well known powerful odour, but the two latter were inodorous. In the two latter cases the effect is due probably to some kind of combination. The conclusions at which these authors arrive are, i. That the chemical composition of the seeds of white and black mustard is essentially different, ii. That the active principle of white mustard * Journal de Pharmacie, 1831, 1. f Ibid. p. 279. Chemical Science. 197 is a substance not volatile, not pre-existing in the seed, and which may be due to sinapisine, combined with some other product ; for when once the latter is separated, the former is not produced. Both contain sulphur, iii. The active principle of black pepper is a volatile oil, having no pre-existence, and not capable of develop- ment without the contact of water, iv. There is probably a principle in this seed from whence the sulphur found in the volatile oil is derived, v. Sinapisine, extracted by alcohol, without the intervening action of water, has not the property of reddening the persalts of iron, nor of evolving odour by the action of caustic alkalies. It is less soluble in alcohol, and contains less nitrogen than the sulpho- sinapisine of M. Henry and Garot, but it contains sulphur essentially* In the same Number is a memoir by M. Faure on the same subject, in which he also shows the important part performed by water, in contributing to the formation of those substances which characterise black pepper, and make it valuable in medicine. In every pharmaceutial preparation into which mustard powder enters, lie considers it essential that as much taste and odour should be de- veloped as possible, and that the powder should first be mingled with water, and then the other substances added. Acids and alkalies do not add to its irritating effects, except perhaps by those which they themselves possess. He arrives at the following chemical conclu- sions : — i. The volatile oil of mustard does not pre-exist in the seeds or powder; water is indispensable to its formation, ii. Besides the well known principles in black mustard, it appears to contain a par- ticular green substance, which appears to aid in forming the volatile oil. iii. Sulpho-sinapisine is one of the principles of black mustard, and accompanies the green matter in almost every operation to which the seed is subject, iv. Ether has no marked action on the consti- tuent elements of the volatile oil. v. Rectified alcohol, and weak acids and alkalies, when added to mustard powder, oppose the for- mation of the volatile oil. 22. SALICINE. MM. Herberger and Buchner have found salicine to be a sub-salt, containing a true vegeto-alkali. The salicia, or base, has all the properties of those bodies, except that it dissolves with facility in water. When burnt it left no residue. It differs from salicine by its alkaline action on litmus paper ; by its crystals, which are ne- vertheless prismatic; by its solubility in water, and by its action on concentrated and dilute acid. It is not so soluble in alcohol as salicine. The sulphate, nitrate, phosphate, acetate, tartrate, oxalate, and muriate of salicia, have been made ; ether does not dissolve them, alcohol does, and upon evaporation leaves them (if there be not enough water of crystallization) in a pulverulent or flocculent form. When heated the salts fuse ; then become dry ; and when more highly heated, fuse and are decomposed with the odour of quinia in * Journal de Pharmacie, 1831, \\ 299. 193 Miscellaneous Intelligence. combustion, leaving a bulky charcoal, which ultimately burns away. The saturating power of salicia is very small. All the salts, except the acetate, crystallize in needles, frequently representing vegetation. The acetate assumes the granular state. Many of them effloresce ; their taste is generally bitter. The salicia was obtained by dissolving salicine in a solution of oxalic acid ; this acid was then separated by lime, &c. &c. The acid part of ordinary salicine was then separated by treating it with phosphoric acid at a moderate temperature. This acid body is volatile, and may be obtained by distillation. It has all the pro- perties of a sub-acid, and is the cause of the aroma of salicine, for pure salicia has no odour of the kind. Pure salicia has no advantages over ordinary salicine *. 23. ON DRACONINE. M. Melandri announced the existence of a vegeto-alkali in dragon's blood, which he called draconia. M. Herberger has obtained this substance in a state of purity, and states that it has no claim to be thus ranked, but that it possesses the properties of a sub-acid, and should be classed with tannin, &c. &c. Dragon's blood consists of fatty matter 2.0 oxalate of lime. . . 1.6 phosphate of lime. 3.7 benzoic acid 3.0 draconine 90. 7t 24. PRECIPITATION OF MORPHIA FROM LAUDANUM. DR. HARE. ' I believe it is not generally known that the addition of ammoniated alcohol to common laudanum will cause a crystalline precipitate of morphia in the course of a few hours. If the precipitate thus ob- tained be dissolved in acetic acid, again precipitated by ammonia, and afterwards collected and dried upon a filter, the morphia will be obtained nearly white, and may be rendered perfectly so by repeat- ing the solution by acetic acid and precipitation by ammonia. I have by these means obtained thirty grains of morphia from an ounce of opium. ' Instead of alcohol impregnated with ammonical gas, a mixture in equal parts of strong aqua ammoniaB and common alcohol will answer. 4 Narcotin is, I find, sometimes spontaneously precipitated in a crystalline form, from a solution of opium in proof spirit. The circum- stances under which I procured it are nearly these: — a quarter of a pound of opium was boiled in a quart of proof spirit, and strained, while warm, through a coarse cotton cloth ; the solution thus obtained being allowed to stand for about twenty-four hours, crystals were observed to be spontaneously deposited on the sides of the con- taining glass jar. These being dissolved in acetic acid, on the ad- * Journ, do Pharmacie, 1831, 225. t Ibid. Chemical Science. 199 dition of ammonia, a precipitate took place, which was collected by a filter and dried. Narcotin was thus obtained in the form of white and beautiful silky crystals, which were readily soluble in sulphuric «ther. * When we consider how often opium has been dissolved in proof spirits by chemists and pharmacopists, it is surprising that crystalline principles, so easily evolved, as are morphia and narcotin, by the pro- cess above described, should have escaped observation until lately, when Sertuerner, by a much less obvious route, had the honour of discovering them*.' 25. COLOURATION OF AZOTED BODIES BY NITRATES OF MERCURY. M. Lebaillif remarked that when certain vegetable and animal sub- stances were moistened with a solution of mercury in nitric acid, they became of a red or amethystine colour, but the effect did not take place with the protonitrate or pernitrate of mercury separately. He and M. Lassaigne investigated this action, and found that a solu- tion containing both prot and per nitrate always produced the effect. Such a solution is always produced when mercury is dissolved by moderate heat in nitric acid ; the production of colour is so ready, that if a piece of animal matter, as dried white of egg, caseum, horn, &c., be moistened with the mercurial solution, it will be red- dened in eight or ten seconds, and if warmed (as upon platina foil, six or eight inches above a candle), will take a rich purple red colour. The effect may be produced even with milk, mucus or dissolved gelatine. Organic substances containing azote were such as, in this way, became coloured. Thus starch was not coloured. Gluten was readily coloured, and it was found easy to find out very small quan- tities of gluten in starch by the rose tint then acquired : but still all organic azoted substances were not coloured. Fibrin and the varieties of albumen, including caseum, horn, wool, milk, mem- branes, &c., gelatine, silk, vegetable albumen, wheat flour, sweet almond, *and some other substances, became coloured. Urea, uric acid, osmazome, picromel, sugar of milk, sugar, starch, lignine quinia, morphia, and the vegetable acids, were either not coloured at all, or only pale yellow. A solution made of one part of mercury in two parts of nitric acid was boiled for four or five minutes, to convert part into per- nitrate, then diluted with its bulk of water, and silk or wool im- mersed for ten or fifteen minutes, at temperatures from 113° to 122° Fah. : it was thus dyed of an amaranth colour, more or less deep, and which, upon the silk, withstood the action of light, and of weak sulphuric acid or alkaline solution. The colour appears due to a combination of the mercurial salt, for the silk becomes brown by a solution of hydrosulphuret ; and 100 parts of white silk increased by 17 or 18| parts during dyeing t- * Sillimau'g Journal, xvi. 365. f Auuales tie Chimie, jdv, 435* Miscellaneous Intelligence. 26. TANNING OF LEATHER BY GRAPE MARC. A medical man of the neighbourhood of Narbonne has announced that the marc of grapes, after being distilled for the purpose of separating the alcohol, is an important assistant to oak bark, in the tanning process. After preparing skins in the usual manner, he placed them in the pits with the marc, in the place of bark. In thirty-five or forty days the tanning was finished. The expected advantages are, i. shorter time ; ii. reduction of the price of oak bark : iii. a more agreeable odour of the leather than that given by oak bark ; iv. greater strength in the leather *. 27. ANALYSIS OF A SALIVARY CONCRETION, BY PROFESSOR GOEBEL, OF DORPAT. The calculus in question was one inch and a half in length, and twenty-eight grains in weight, and consisted of a great number of concentric layers ; it was examined in the following manner. The digestion of fifteen grains of the powdered substance with sulphuric ether yielded a colourless extract, by the evaporation of which one- eighth of a grain of yellowish white fatty matter was obtained, which had no taste or smell, was insoluble in water and alcohol, and on being incinerated exhibited a slight trace of iron. The residuum of the powder from the digestion with ether was boiled with alcohol, the liquid evaporated, and half a grain of a yellowish substance obtained, half of which was soluble in water; the solution was of a weak saline taste, and had the odour of osmazome ; it was pre- cipitated by the oxalate of ammonia and nitrate of silver. The other half, which was not plissolved by the water, was soluble in ether, and exhibited all the properties of the ethereal extract. The remainder of the powder being boiled with water, a colourless solu- tion was obtained, which, during evaporation, became of a red colour, and yielded one grain and a half of a dry brownish residuum, which was perfectly soluble in water, but not soluble in, nor dis- coloured by, ether or alcohol. The red colour of the solution, which very much resembled that of the sulpho-cyanate of iron, was entirely destroyed by adding a few drops of liquid ammonia or muriatic acid; and as the incinerated mass of the brown residuum, after having been heated with a few drops of nitro-muriatic acid, and dissolved in water, was precipitated by the tincture of galls, of a bluish black, by the ferro-cyanate of potash, of a blue, and by the sulpho-cyanate of potash, of the original red colour, there can scarcely be any doubt that it proceeded from the presence of sulpho-cyanate of iron. In order to ascertain this still more clearly, nine grains of the sub- stance were boiled with distilled water, and on adding a few drops of the solution of chloride of iron, the liquid was found immediately to become of an intense red colour. No trace of potash could be, * Recueil Ipdustrielle, xvi. 85. Natural History. 201 found, but there was a considerable portion of soda, and it is accordingly reasonable to suppose that the sulpho-cyanogen had originally been combined with sodium, and only during the evapo- ration become united to the iron. The residuum from the powder which had been successively submitted to the action of ether, alcohol, and water, was now heated with muriatic acid, which formed a transparent solution, and an insoluble gelatinous substance of one- sixth of a grain in weight, after having been dried. The solution was saturated with ammonia, and yielded twelve grains and a quarter of phosphate of lime, with a small quantity of animal substance, as appeared from the smell during combustion. The remainder of the solution being mixed with oxalate of ammonia, formed a precipitate of oxalate of lime, which, on being ignited, was found to be one- eighth of a grain ; besides there were some traces of carbonate of magnesia. Fifteen grains of the salivary concretion would accord- ingly consist of — 0.375 of fatty substance, 0.250 „ osmazome, i &nn (Sulphates, iron, chloride of calcium, sulpho-cyanide J " \ of sodium, 0.166 „ Animal substance (mucus?), 12.250 „ Phosphate of lime, 0.212 „ Carbonate of lime, 0 . 247 „ Carbonate of magnesia, water, and loss. 15.000* § III. NATURAL HISTORY. 1. POWER OF CARBONIC ACID ON THE LUNGS. WHEN M. D'Arcet went to visit the very abundant and curious source of carbonic acid, existing at Montpensier, in the department of Puy de Dome, he endeavoured to ascertain personally the effect of the gas when respired. He kneeled down, therefore, near the larger source, supporting himself on his hands, and advanced his head slowly downward, intending to raise himself the moment he felt any indication of risk : but on commencing the respiration of the gas, the effect of feebleness and extinction of power was so sudden, that he fell down flat, with the face entirely immersed in the current of carbonic acid, and would have lost his life, but that the guide whom he had forewarned, raised and carried him away to the fresh air. M. D'Arcet proposes two curious uses of the place. The nature * Schweigger-Seidel's Jahrb. 1830, iv. 403. 202 Miscellaneous Intelligence. of the ground, assisted by certain protecting hedges, will enable the carbonic acid to collect in large quantities. A cistern is to be formed at the lowest level, and then when animals come to drink the water, or are tempted by the green shade, they will be killed, and thus much game is calculated upon for the advantage of the village. Then a house is to be built with an inclined floor, a pully, a double rope, &CM so that a dog may be tied to the rope, led into the car- bonic acid atmosphere in the house, rendered insensible, hauled up again and revived by the fresh air ; and thus by making the celebrated experiment of the Grotto del Cane in a scientific way, much com- pany, it is expected, will be drawn to the place* 2. ON THE PHENOMENON OP BLUSHING. M. E. A. Lauth observes, that he is not aware that any precise in- formation has been afforded as to the kind of vessels which produce the colour of the face. Most physiologists merely say that it depends upon the capillaries. M. Lauth states, that if the arteries are suc- cessfully injected, the whole of the face becomes of an uniform red tint. It cannot, therefore, be these vessels which produce the phe- nomenon of blushing. He has derived the following results from a perfect injection of the facial veins: the cheeks were deeply coloured, the chin, the tip of the nose and the forehead obtained a slighter tint, and the other parts of the face were still less coloured. This kind of colouration resembles that which is produced by men- tal emotions during life, and we may therefore conclude that blush- ing depends in part upon venous congestion f. 3. GENERAL EMPHYSEMA FORMED BY A COMBUSTIBLE GAS. This singular case was described by M. Bally, at the Academic Royale de Medecine. A man twenty-five years of age, who had been ill fifteen days, was admitted into L'Hopital Cochin, with symp toms of typhus fever. He also complained of severe pain in the left thigh, and whilst he was in a state of delirium, he said he had been bitten on the knee by a dog. The limb was most attentively examined, but not the slightest trace of such an accident could be discovered. The thigh and scrotum were much swollen. He died the following day. Dissection eight hours after death. The surface of the body was soiled by blood, which had also transuded through the integuments of the thighs : some blood had also been dis- charged from the nose. The whole body was emphysematous, but the left inferior extremity was in this state to a very high degree ; it was double its natural size, of a brown colour, and covered with numerous phlyctenaB, some black, of great extent and collected in clusters, from which escaped a reddish serous fluid, mingled with a quantity of gas ; others were white, and from these nothing but air escaped. * Recueil Industrie!, xv. 220. f Mem. de la Society &c. de Strasbourg. Natural History. 203 The limb sounded upon percussion, and when it was pressed with the hand crepitation was distinctly heard ; the abdomen was much distended with gas : the face and temples were deeply injected with blood, and were of a violet colour. Upon dividing the scalp a large quantity of dark red blood escaped. The nerves and lungs presented no remarkable appearances, heart pale, and void of blood. In the intestines were observed those alterations which are so com- monly detected in cases of typhus fever. Bubbles of air filled the vessels of the pia mater and the left vena saphena. The lymphatic ganglions of the mesentery were enlarged, and contained gas, which took fire from the flame of a taper, and produced an explosion. The same phenomena also followed the exit of air which was contained in the legs, thighs, and scrotum, where incisions had been made into these parts. A puncture was made in the abdomen, and the gas which escaped also took fire and burned for some time ; the flame was blue at its base and white at its summit. The combustion extended to the puncture which had been made with a trocar. The edges of this aperture became black, and were consumed, and the aperture itself was enlarged to double the size it had originally been made. The gas which was contained in the subcutaneous cellular tissue of the thorax was equally inflammable *. 4. POISONING BY MOULDY BREAD. Dr. Westerhoff attended, in 1826, upon two children of a labourer, who had been simultaneously attacked with the following symp- toms. The eldest, ten years of age, had his face red and swollen, his countenance was animated and bewildered, tongue dry, pulse feeble and quickened, head-ache, giddiness, unextinguishable thirst, violent cholic, desire to sleep, and alternate unsuccessful attempts to vomit; subsequently sudden vomiting and very abundant alvine evacuations, after which very great faintness, indifference to every- thing, and sleep only for a few minutes at a time. The younger, eight years of age, was even more violently attacked. Having understood that they had eaten the preceding day only a piece of old mouldy rye bread, Dr. Westerhoff prescribed a demulcent treatment, and they soon recovered. Some time afterward, several boatmen having eaten some mouldy rye bread were attacked with similar symptoms, but they were quickly relieved by vomiting, which came on spontaneously. The question suggested by these cases is, whether this kind of poison- ing arises from an alteration in the quality of the bread, or from the vegetation which constitutes mouldiness (mucor mucedo) t« 5. CURE OF SCROFULA BY IODINE. A report, expressing the utmost approbation, has been made by MM. Dumeril and Majendie to the Academic des Sciences at Paris, upon M. Lugol's application of iodine, in scrofulous cases, at the * Med, and Phys, Jour., 1831, p. 514, t Archives G6n6rales. 204 Miscellaneous Intelligence. hospital of St. Louis. They state that that very common and dreadful disease, which was formerly considered as incurable, and, by a rigorous rule, subjected its sufferers to exclusion from the hos- pitals, may now be cured ; that it is not merely cases in their first stage, but those that were exceedingly advanced (scrofulous con- sumptions), that were cured. Where the glands, organs, articula- tions, and bones had suffered greatly, still a month sufficed to cure the patients. M. Lugol has operated only in the worst cases ; such as, having no hope, came to the establishments to die. * M. Lugol does not claim the discovery of the utility of iodine in scrofula, but, by the great number of cures which he has effected by his zeal and perseverance, and by the light he has thrown upon the internal and external application of iodine, in various states of preparation, M. Lugol has advanced medical science an important step.' The Aca- demy approved the report*. In 17 months, 109 scrofulous patients had been treated with iodine only. At the end of 1828, 39 were still under the physicians' hands, 30 had left the hospital much improved : with 4 the appli- cation had been useless ; 36 were perfectly cured t. 6. ON THE USE OF THE SECALE CORNUTUM. The following general results, obtained by Dr. Villeneuve in 720 cases, are quoted by Dr. Armour in a paper upon this subject: — i. In 600 the success was complete in cases of labour, properly so called, i. e. for the expulsion of the fetus alone, living or dead, at the term or otherwise, the pregnancy being simple or of twins, ii. Five cases of success of expulsion of the placenta, iii. Five cases of success in flooding after delivery, iv. Sixteen cases of incomplete success, which consisted of cases in which the ergot excited the ex- pulsive powers for a certain time only, the delivery not being termi- nated naturally till several hours after the employment of the medicine, or of cases in which, after having advanced the labour to a certain degree, the application of instruments became possible, and was made. v. Eighty-two cases of complete failure, in which the ergot had no sensible effect, producing no return of uterine action, whatever doses were given, vi. Twelve disagreeable or fatal results, either for the mother or child, attributed by different authors to the immediate action, or to the secondary effects of the ergot. This proportion of seven and a half of success to one of failure, is seldom furnished by other therapeutical agents employed to combat any morbid state J. 7. ON THE HoLOTURES AND PARTICULARLY OF THE HOLOTHURIA PHYSALIS. — (Linn.) This species of molluscae, vulgarly galere in French, and in Eng- * Revue Ency. xlix. 239. f Recueil Industrielle, xv, 229, £ Med, Phys, Journal, 1831, 462, Natural History. 205 lish, « Portuguese man-of-war,' so rare in collections, so difficult to preserve, so incompletely described by naturalists, and, it must be owned, so little worthy of observation when deprived of life, is, perhaps, one of the most curious inhabitants of the equatorial seas. There are few navigators who have not sought to ascertain some of the habits of life of these singular animals, whose extraordinary form, brilliant colours, and habit of remaining floating on the sur- face of the water during calm weather, has attracted the attention of all navigators. These habits are the origin of the vulgar names given to them by the sailors. The body of the smallest of these creatures which we have been able to observe, was about 2 centimetres (0.8 of inch) long, and that of the largest was 17 centimetres (6.7 inches). Their form, which it is impossible to compare to that of any other animal living, rather resembles a small bladder stretched and filled with air, of an azure blue, slightly streaked with deeper tints and green ; their body, almost cylindrical, is surmounted by a crest, which is in plaits, very moveable, and edged by the most lively tints of purple and rose-colour. This little crest serves the animal for a sail, and by the disposition which it gives it, regulates its movement in nearly the same manner as a ship. According to the strength of the wind, it spreads, rests, or compresses its sail, and in heavy weather, it allows itself to float, by means of a respiratory apparatus of a peculiar construction. The lightness of its body is such, that it appears resting on the water, and when plunged in alcohol it floats again to the surface of that fluid. The lower and middle part of the animal is armed, at different lengths, with tubes, papillae, and retractile feelers, some of which are from sixteen to eighteen feet long, disposed spirally or in chaplets of the most beautiful blue, and most delicate rose-colour, and serve at once as organs of absorption, defence, and locomotion. These tubes, papillaB, and fibres, contain a viscous matter, which produces pustules on the human skin, and occasions a pain similar to that of a large but superficial burn. This property is not easily got rid of; vessels in which one of these animals has been plunged, must be washed several times in water, and carefully scoured before they can be used without inconvenience ; and linen, which had merely been rinsed in soap and water, had this quality of irritation fifteen days after it had been used in making observations on these ani- mals. Cutting these feelers does not produce death, at least for a considerable time ; and incisions made transversely in the body with scissors do not deprive the animal of life. The membranous crest appears to have more irritability than the other appendages, and the animal appears to contract itself, and to suffer more when tormented there than in any other part. Naturalists suppose that the holothurus feeds on animals of all kinds, occasionally on some of a very considerable relative size, and that they have a very strong and active digestion. They, in their turn, serve as food to species of the scombri and medusa, against which their weapons of defence are unavailing 206 Miscellaneous Intelligence. 8. DEFENCE AGAINST FLIES, USED BY THE BUTCHERS OF GENEVA. It is said that the butchers of Geneva have for a long time used the oil of laurel as a substance which prevents the flies from approach- ing their meat. The odour of this oil, though strong, is not very disagreeable, and the flies will not approach the walls or parts which have been rubbed with it. The person who describes these effects says, that he has, in this way, guarded the gilt frames of mirrors and pictures most perfectly from flies *. 9. THE PALM OF CHILE. It is chiefly in the middle province that the palm of Chile (Micrococcos) is found. It is not a common tree, being very partially distributed, but several of the estates owe much of their value to the number of palms upon them ; and, although the stem is useless, the leaves, sap, and fruit, yield a large income to the proprietor. For thatching houses, the leaves are considered better and more durable than any other material ; the sap, boiled down to a syrup, is used as a sub- stitute for honey, and has a very agreeable flavour ; and the small cocoa-nuts, about an inch in diameter, of which every tree produces a great number, are highly esteemed, and form a considerable article of export to Peru. A curious method is employed to free the nut from the green husk in which it is enveloped, a process that was formerly attended with a great loss of time and labour. A number of cows and oxen are driven into an enclosure, where a quantity of the fruit is spread, and being very fond of its husk, they immediately begin to feed on the fruit, only slightly masticating it in the first instance, and swallowing the whole ; afterwards, while chewing the cud, the nuts are rejected; and when the meal is finished, a heap of them is found before each of the animals, per- fectly free from the husk, the cattle being thus supplied with food at a season when little grass remains on the hills, at the same time that they effectually perform a very useful operation t. 10. DESTRUCTION OF WEEDS IN PAVED PATHS AND COURTS. The growth of weeds between the stones of a pavement is often very injurious as well as unsightly. The following method is adopted at the Mint at Paris and elsewhere with good effect. One hundred pounds of water, twenty pounds of quick lime, and two pounds of flowers of sulphur, are to be boiled in an iron vessel ; the liquor is to be allowed to settle, the clear part drawn off, and being more or less diluted, according to circumstances, is to be used for watering the alleys and pavements. The weeds will not appear for several years J. 11. PRESERVATION OF HAY. Eye-witnesses assert that in Russia the inhabitants usually preserve * Recueil Industrielle, xv. 247. f Botanical Miscellany, ii., 202. % Recueil Industrielle, xv, 246, Natural History. 207 hay with all its natural verdure. To obtain this effect, the grass, as soon as cut, is (without being allowed to fade) instantly stacked. A kind of chimney, made with four rough boards, is con- structed in the middle of the stack, and it appears that this channel prevents the accumulation of heat from fermentation ; and that the herb thus treated retains all its leaves, its colour, and its primitive taste. The size of the stacks is not mentioned *. 12. REMARKABLE PROPAGATION OF WIND. Whilst the bells were ringing to church, at Albany, on the 12th of July, 1829, a very violent gust of wind from the south-east passed over the town. This gust passed over New York, which is to the south of Albany, when the service had proceeded for some time: so that this south wind was rendered evident in the northern town an hour nearly before it was felt at the southern position, and it had been propagated from north to south in the direction exactly contrary to that in which it blew. Franklin remarked that violent north-west winds in the United States frequently had their origin in the quarter towards which they passed, and was inclined to attribute them to great and sudden alterations in the atmosphere of the Gulf of Mexico. To explain the present instance in the same manner, a diminution in the atmos- pheric pressure to the north of Albany must be considered as having occurred f. 13. THOUGHTS ON NORTH AND SOUTH WINDS. — (By M. Alphome Blanc.) It has been generally admitted that winds are mostly, if not always, caused by dilatations or condensations of the air due to changes of temperature. In fine, quiet weather, the wind from the east in the morning, often becomes south at midday, and west in the evening, and may, with great appearance of reason, be attributed to the dilatation of the air by the sun in the east, south, and west in succession, of the place of observation. It is also known that a wind often blows in one place before it blows in another place to windward of the first ; and in such cases it has been supposed that the effect is due to some great condensation in the air at some place to leeward of the place where the wind is felt. Now the barometer should be affected differently according to the nature of the cause of wind. If condensation occurred about the pole, the air of surrounding places should flow towards it, a par- tial vacuum should occur in those places, forming a south wind gradually extending towards the south, and the others to which the wind should reach, and the barometer should fall at those places. But if expansion of the northern air occurred, a north wind should commence at the north, and be propagated to the south, driving or accumulating the air before it, and the barometer should rise in all those places to which it reached. * Recueil Inclust., xv, 247. f Ann, de Chimie, xlv, 420. 208 Miscellaneous Intelligence. The effects due to air passing from the north southwards should be greater, because, arriving at warmer regions, it would become heated, and tend to dilate ; the contrary effect would occur with air passing from the south to the north. But these effects would be smaller, if the changes of tension which act as causes of the wind, occurred to the south instead of in the north, because the air, driven forward by expansion, would contract as it travelled northwards, and vice versa. The variations of the barometer between the tropics is scarcely any thing ; the winds are very regular, the cause is permanent, and the equilibrium appears constant. From this regularity, it may be con- cluded, that the north and south winds which we have, originate in the north; for how can it be imagined that a south wind should ge- nerally come to us from a place where the contrary wind is constant? On this view, the south wind would generally be caused by a con- densation, and the north wind by an expansion of the polar atmos- phere, and the barometer ought to fall with south winds and rise with north winds. This effect is usually observed. Though the south wind, in passing northward, is cooled, and de- posits part of its vapour in clouds and rain, it would appear, from the above reasoning, that such deposition is not the cause of the descent of the barometer. If vapour were the cause, the effect ought to occur in every place where there is rain ; but this does not hap- pen. It may easily be conceived, that although the south wind may ordinarily be caused by condensation of air in the north, and be ac- companied by depression of the barometer, it may sometimes be due to dilatation in the south, and then the barometer would rise *. 14. NITROUS ATMOSPHERE OF TIRHOOT. Tirhoot is one of the principal districts in India for the manufacture of saltpetre : the soil is every where abundantly impregnated with this substance, and it floats in the atmosphere in such quantities, that during the rains and cold weather it is attracted from thence by the lime on the damp walls of houses, and fixes there in shape of long downy crystals of exceeding delicacy. From damp spots it may be brushed off every two or three days almost in basketsful. In con- sequence of all this, the ground, even in hot weather, is, so damp that it is extremely difficult either to get earth of sufficient tenacity to make bricks, (the country being quite destitute of stones,) or, when made, to find a spot sufficiently solid to sustain the weight of a house. Even with the greatest care the ground at last yields, and the salt- petre corrodes the best of the bricks to such a degree, that the whole house gradually sinks several inches below its original level. Houses built of inferior materials of course suffer much more ; one, of which the inner foundations were of unburnt bricks, absolutely fell down whilst I was at Mullye, and the family in it escaped almost by miracle. My own house, which was not much better, sank so much, * Aimalqs de Chimie, xlv. 421. Natural History. 209 and the walls at bottom were so evidently giving way, that I was compelled, with extreme expense and inconvenience, to pull down the whole inner walls and build them afresh, in a more secure manner. From the same cause a new magazine, which government directed to be built with an arched roof of brick-work, was, when complete, found so very unsafe, that it was necessary to demolish it entirely and rebuild it on a new plan, with a roof of tiles*. 15. PROGRESSIVE MOTION OF THE GLACIERS. The ladder which M. de Saussure used in crossing the crevices in the ice during his first visit to the Col du Geant, and which he left on the upper part of the glacier, has lately been discovered imbedded in the Mer de Glace, in a situation nearly opposite to the aiguille called l«e Moine. This ladder, moving on with the body of ice, will thus appear to have advanced three leagues since the year 1787. Captain Sherwill, in his relation of his ascent of Mont Blanc, speaking of the glaciers, says, 4 In traversing these stagnated oceans, very large blocks of granite, of many tons weight, may be seen riding on the surface of the ice. These blocks have afforded the means of ascertaining a fact of importance. The experiment I am about to relate to you was made last year by some of the guides of Chamouni. Two poles were erected, one on each side of the glacier, out of reach of its movement, and so placed as to be in a direct line with a block of granite. In the course of twelve months, this block had entirely changed its position, as respecting the two poles, and had advanced about one hundred yards on its march towards the valley, a clear proof that the glaciers do move on, and are continually diminishing at their lower extremity, by the melting of the ice, and increasing at the upper end by the constant snows.' If the progress made by the ladder of M. de Saussure taken for one year, and the result of the experiment made at the instigation of Captain Sherwill, should not appear to agree, it must be recollected that from the Col du G£ant to the spot where the ladder is, is a very rapid descent, and of course the march of the glacier would be rapid in proportion ; whereas the experiment of Captain Sherwill was made on a level part of the same glacier, the Mer de Glace, where the ice is of a more compact texture than that at an elevation of above ten thousand feet, and consequently its progress towards its final issue would be somewhat slower t. 16. ON THE COMPARATIVE QUANTITY OF SALT CONTAINED IN THE WATERS OF THE OCEAN. — (By M. E. Lenz.) The following experiments were made on the expedition of Captain Kotzebue : — Those with water at seven different places of the ocean, and at various depths, tended to prove, that from the equator to * Calcutta Transactions. t Philosophical Magazine, N. S. ix. 32. VOL. II. AUG. 1831. P 210 Miscellaneous Intelligence. 45° north latitude, the ocean contains, at the same place, the same quantity of salt, as low at least as 1000 toises. For ascertaining the quantity of salt contained in the water on the surface of the ocean, the observers used hydrometers which, by laying weights on them, were made to sink into the water to a mark on the thin neck of the instrument. It is well known that Dr. Erman has ascertained the contraction of salt water of the specific gravity 1*027 for every de- gree of the thermometer, from 12 R. (59 F.) to — 3°R. (25J F.), and has proved that such water has no maximum of density, before freezing, like common water. With a view to the investigation here under consideration, the table of Erman was extended, by experi- ments made for the purpose, as far as to 24° R. (86 F.) It was then ascertained that a small difference in the specific gravity of the water had no great influence on the law of contraction by change of temperature, since experiments instituted with this view proved that two portions of water, whose specific gravity was 1*02 and 1*03, (between which limits undoubtedly all waters of the ocean are comprehended,) observed nearly the same law, and perfectly so at those temperatures at which observations are made on the ocean. The experiments could be very approximately represented by this expression for the density (rf) of water whose specific gravity = 1*027, arid whose temperature is (£) degrees of Reaumur's thermometer : — d~ 1-0-0002053. 2 + 0-0000003723. t*- 0.000000188086. t*. and by this formula the numerous observations of specific gravity of water, in different parts of the ocean, were reduced to the same temperature, viz. 14° R. (63J F.) The general result of all the observations is as follows : — i. The Atlantic Ocean contains more salt than the Pacific Ocean, and the Indian Ocean is, therefore, more salt near the Atlantic than near the Pacific. ii. In each of these great oceans there is a northern and a southern maximum of salt ; the northern is farther from the equator than the southern. The minimum is, in the Atlantic, a few degrees north of the equator ; the same is probably the case in the Pacific : there were, however, not sufficient observations to prove it. iii. In the Atlantic Ocean the water is more salt to the westward ; there seems to be no such difference in the Pacific. iv. The greatest specific gravity of the water in the Atlantic Ocean, at the northern maximum, in lat. 20^° and long. 40° W. of Greenwich, was found to be = T02856 ; that of the Pacific, at the southern maximum, in lat. 17° and long. 119° W. r= 1 -028084. v. To the northward of the northern maximum, and to the southward of the southern maximum, the specific gravity of the water conti- nually decreases with the increase of latitude. It is clear that the quantity of salt in the water on the surface of the ocean must mainly depend on the evaporation ; and as this de- Natural History. 211 pends again on the temperature of the air and on the wind, it will be found that the different degrees in which these, causes operate together, will afford a satisfactory explanation of the circumstances here described *. 17. HOURLY OBSERVATIONS OP THE BAROMETER IN THE FORTRESS OF CAVITE. These observations were made by the scientific men attached to Cap- tain Kotzebue's expedition in the year 1823 — 1826, on the Island of Luzon (14° 34' north lat., arid 239°9' west of Greenwich) for ascer- taining the periods of its regular falling and rising during twenty- four hours. The barometer was kept in a room six toises above the level of the sea, in which the temperature was nearly the same day and night, (about 25° Centigrade, or 77 Fahr.) and the obser- vations were made on eleven different days between the 12th and 26th of December. The following are the general results deduced from the whole of the observations. The barometer has a maximum of height at . . 9h V 1" A. M. it then falls till . 4 28 6 P. M. on an average 1 . 04 line ; it rises again till . 9 58 3 P. M. „ 0.687 „ and falls again till . 4 30 0 A. M. lastly it rises again till 911 A. M. on an average 0.44 5 18. COMPARISON OP THE MEAN TEMPERATURE OF THE AIR AND ! THE WATER ON THE SURFACE OF THE OCEAN WITHIN TWENTY- FOUR HOURS. These observations were made on the expedition commanded by Captain Kotzebue during the years 1823 — 1826. Four observa- tions were made within twenty-four hours ; one half an hour before sunrise, the second an hour and a half after noon, and the two others at equal intervals between the afternoon's and next morn- ing's observations. The result which is obtained from all the obser- vations is this : in the zone from 45° N. lat, to 30° S. lat., the mean temperature of the water on the surface of the ocean, whether taken for the whole year, for single months, or for single days, exceeds the corresponding mean temperature of the air with which it is in contact. Beyond these latitudes, the means taken for twenty- four hours, during the summer months, (there being no observa- tions during the winter months,) varied, sometimes the one, some- times the other being higher. The following were the highest mean temperatures for twenty- four hours : — In the northern hemisphere, of the air=27°.225 C (81°.0 F.) ; of the water 27°. 55 (81°. 6 F.) In the southern hemisphere, of the air=26°.975 C (80o53 F.) ; of the water 28°. 30 (82°. 9 F.)t. * Petersburgh Transactions, 1830. f Ibid. P 2 212 Miscellaneous Intelligence. 19. PROFESSOR OLTMANNS ON THE GEOGRAPHY OF SOUTH AMERICA*. It is well known that the results of the expedition of Malespina, which was most richly fitted out for scientific investigations, and most ably conducted, have never been communicated to the public. M. Bauza, a skilful officer attached to the expedition, communicated to Professor Oltmanns the astronomical observations made on that ex- pedition, which he has saved from the fate of the other fruits of that ill-starred expedition, on condition that he would recalculate them. Professor Oltmanns has redeemed his pledge, and in laying before the world the results of his calculations of the observations of Malespina, together with those of other observers, he confirms the opinion expressed by Bauza, that the former calculations were very inaccurately executed. He likewise agrees with M. Bauza respecting the inaccuracy of the observations made on board the Conway, some of which, when recalculated by Professor Oltmanns, gave results differing more than twenty minutes in arc from what is most probably true. From the numerous list given by Professor Oltmanns, we extract the following positions of some remarkable places on the coast of South America, as corrected by Professor Oltmanns; among which the longitude of Rio Janeiro depends on a great number of occultations of Jupiter's satellites. Places. Latitude. Longitude west of Paris. Rio di Janeiro . . .22° 54' 45° 36' 13" Buenos Ayres . . . 34 36 40'' 60 47 0 Monte Video (Observatory) 34 54 40 58 36 50 San Carlos de Chiloe . 41 52 0 76 11 20 La Concepcion . . . 36 49 30 75 25 55 Valparaiso ... 33 2 0 74 2 10 San Jago de Chili . . 33 26 15 73 17 17 Coquimbo ... 29 56 40 73 43 48 Callao (Casillo del Callao) . 12 3 40 79 34 31 Guayaquil . 2 12 0 82 18 10 20. ON BEAUCHAMP'S GEOGRAPHICAL POSITIONS IN THE EAST. (By Professor Oltmanns.')^ It is well known that the geography of the interior of Asia was per- fectly unknown till within about half a century, and even at this, moment there are, in the interior of Persia, and other central regions of Asia, large tracts without a single place whose position is deter- mined by astronomical observations. We are indebted to two travellers, Niebuhr and Beauchamp, for the first advances made ia the geography of the south-western parts of Asia. Niebuhr's ob- * Berlin Academy, Year 1827 : Berlin, 1830, 2d Part, p. 37. f Mem, of Berlin Academy, Year 1827. ' Berlin, 1830, p. 139, Natural History. 213 servations were in that part, however, confined to latitudes, while the lunar distances observed by him in Egypt have, after a lapse of fifty years, been calculated by Burg, and received by the learned with the praise which they deserve. Beauchamp made two scientific journeys to the East, but was much better provided for making observations on the second, than on the first. The published obser- vations of this rather capricious traveller did not answer to the high expectations that had been formed. The numerous errors, espe- cially in writing-, have baffled the exertions of some of the ablest and most indefatigable calculators ; and the suspicion that some of his observations have been subsequently corrected by himself, as well as the circumstance that his observations at Casvin of a lunar eclipse did not give the position of the Caspian Sea, near which that place is situated, have lowered the estimation of Beauchamp's labours. Professor Oltmanns obtained a manuscript of some of Beauchamp's observations which was supposed to be lost, entitled ' Relation Historique et Geographique d'un Voyage de Constan- tinople par mer, Tan V de la Republique. Par le Chevalier Beau- champ. 38 pp. fol.' In this he was likewise much disappointed, as, of many observations, results only were given; while in others it appeared that Beauchamp always neglected the aberration and nu- tation. Notwithstanding this, Professor Oltmanns has thought it worth while to recalculate the observations by the latest tables, and he has thus determined the following geographical positions : Trapezunt. — Lat. (mean of two observations) 41° 2' 18". Long, (by chronometers, lunar distances and eclipses of Jupiter's satellites, all agreeing tolerably well), mean 37° 11' 18" E. of Paris. Sinope. — Lat. (mean of seven observations of the sun and stars) 42° 1' 42". Long, (mean of chronometers and eclipses of Jupiter's satellites) 32° 45' 33'' E. of Paris. Gydron. — Lat. (one star observed) 41° 54' 6", Long. 3° 37' E. of Constantinople. Jeniki. — Lat. by three observations of the sun, mean 41° 59' 49''. Long, by chronometers, 31° 16' 15". Amasra. — Lat. (according to Beauchamp's own calculation), 41° 46' 8". Long. 29° 50' 30". Neracle du Pont or Eregri. — Lat. by four stars, mean 41° 17' 6". Long, by two eclipses of Jupiter's sa- tellites, mean 29° 9' 56" E. of Paris. Bagdad. — Here Beauchamp had an observatory on his first expedi- tion : lat. then found, 33° 19' 50*. Long, by eclipses of Jupiter's satellites, a solar eclipse, and an occultation of J upiter by the moon, all nearly agreeing, mean, 42° 2' 5"E. of Paris. 214 . Miscellaneous Intelligence. 21. EUMENIAN MARBLES. A discovery of great historical importance has lately been made at Autun, a city about 160 miles to the south-east of Paris. It was well known that Eumenes had placed in the schools which bore his name a marble tablet representing the itinerary of the Roman roads leading from the territory of the ^Edui in Celtic Gaul, to Italy. This marble, having been accidentally broken, was employed, in common with a number of other ruins of ancient monuments, in forming the foundation of the Abbey of St. Jean-le-Grand, founded at Autun at the close of the sixth century by Brunehaut. This precious marble was considered as irretrievably lost ; but M. Mar- tigny, of Autun, has undertaken an excavation, by means of which he has already recovered a fragment of the itinerary, a marble ewer, a capital, &c. Should M. Martigny succeed in recovering the whole of the marble, it will probably be of great use in correcting or completing the Itinerary of Antoninus, the table of Peutinger, and the Arundel marbles. The Academy of Sciences of Dijon has the fragment which has been found, and is preparing to have it engraved and published. 22. ON THE ILLUMINATION OF THEATRES. — (Additional Remarks, by Mr. Ainger.) Since the paper printed at page 45 was written, I accidentally learned that an essay on the same subject had been published by M. Lavoisin, in the Memoirs of the French Academy for 1781. I have examined the essay in question, and I find, as might have been expected, that the objections to the existing mode of illumina- tion had been fully felt and expressed half a century since. The plan suggested by M. Lavoisin is, however, very different from that which I have submitted. In the first place, M. Lavoisin retains the foot-lights, in which are, I think, comprised nine-tenths of the objections to the present system ; preserving these, it seems scarcely worth while to incur any considerable expense to remove the other comparatively trifling evils. M. Lavoisin, in addition to the foot- lights, suggests the use of certain powerful lamps with reflectors above the stage for the purpose of illuminating the centre scene when it is so far back as to be ineffectually lighted by the foot-lamps. He proposes to light the audience by nine burners, with ellipsoidal reflectors, placed above the ceiling, which is to be perforated for the purpose ; but as this would leave the ceiling itself quite dark, he adds other lamps round the walls, with a view to remove that defect. It is gratifying to find that the subject has been thought suf- ficiently important to merit the attention of so distinguished a phi- losopher as M. Lavoisin ; and on his authority I venture to hope that it will be taken up by those who alone have the means of making an effectual experiment. '/>:. > -Z andtm,. jPubliah&d iy John, J/io^'m 7t37. ' tf& A Lraiui>> JHJEAID (0)Jr J]&'<0>ILA. A NKW ZEALAND CHIEF. To illustrate 'An Account of the Mode of preparing Human Tie ads in. New Zealand By George Bennett, Esq, MR C S Kc . Drasm from the original Head by M A H '.u-iby "M. Gauci JOURNAL THE ROYAL INSTITUTION OP GREAT BRITAIN. THE MODE OF PREPARING HUMAN HEADS AMONG THE NEW ZEALANDERS, WITH SOME OBSERVATIONS ON CANNIBALISM*. By GEORGE BENNETT, Member of the Royal College of Surgeons in London, &c. &c. TT is now fully ascertained, that the natives of the New Hebrides, the Marquesas, New Zealand, and other Poly- nesian islands, are cannibals ; yet it is among the New Zea- landers only that the custom obtains of preserving the heads of their enemies as tokens of victory, and as objects of con- tempt. There is something analogous to this among certain tribes of Africans, who preserve the skulls of their enemies for purposes similar to those of the New Zealanders. Captain Tuckey observes, respecting this custom among the natives on the river Zaire or Congo, ' the first objects that called our attention were four human skulls, hung to the tree, which we were told were those of enemies' chiefs taken in battle, whose heads it was the custom to preserve as trophies ; these victims, however, seemed to have received the coup dc grace previous to the separation of the head, all the skulls presenting com- pound fractures/ — page 101. The New Zealanders some- times, however, preserve the heads of their friends, but for very different purposes — those of paying respect to the memory of the deceased ; to show to their relations who have been * The plate was given in the last Number. You II. Nov. 1831. Q 216 Mr. Bennett on the Mode of preparing absent at the time of their death ; and that lamentations may be renewed over them at certain periods. The preparation of the Moko, or head, among the New Zealanders, most effectually prevents decay, and is at the same time compatible with the perfect preservation of the fea- tures. The process, as practised among them, is as follows: — After the head has been severed from the body> the base of the skull is broken by a stick or stone, and the brain removed, &c. ; the cavity of the cranium is then frequently washed out until it is well cleansed. The head is then dipped for a few minutes in hot water, which causes the cuticle to peel off; they are careful at this time not to touch the hair, as by so doing it would readily come off, but it afterwards, when cool, becomes more firmly fixed than before, as is well exemplified in the specimens brought to this country. A piece of thin stick is next placed up the septum narium, for the purpose of keeping the nose in shape, aided also by another piece placed internally to bear against the nose as a prevention against its sinking; the nostrils are also stuffed with muka or flax, or pieces of soft wood, for a similar purpose ; the eyes are taken out (if those of a chief they are eaten, if otherwise they are thrown away), and the eyelids are stitched up, as well as the mouth, for the purpose of preserving their shape. A pit having been pre- viously dug, hot stones are brought and placed in it : this pit, which is indeed the usual native oven, is so constructed, that it is covered over, with the exception of an aperture above of sufficient size to permit the base of the head to rest upon it. Water having been previously thrown over the hot stones, and repeated as often as considered necessary, a steam is pro- duced, which is also increased by the addition of leaves mois- tened with water ; the base of the head is placed over this aperture, and the heat and steam ascend into it; the hot stones, water, &c., to keep up the requisite heat and steam during the process, being renewed as often as required by the person in attendance, until the preparation is completed. The person whose duty it is to attend to the preparation of the head is careful, when any of the skin of the face appears to wrinkle, to smooth down and preserve it in shape. The time occupied in this process previous to its completion is from twenty-four Human Heads among the New Zealanders. 217 to thirty hours. After the head is prepared, it is removed from the oven, placed upon a stick in the sun, and is frequently oiled, but this latter process is not considered necessary for its preservation, but is intended only to give it a more finished appearance. The adoption of this simple, but at the same time excellent method of preserving the human heads, would enable a valuable series to be formed, illustrative of the varieties of the human race. The object of the natives in thus preparing the heads of their enemies, is to preserve them as trophies, as well as for the gratification of their revengeful feelings; they exhibit them in their war-dances, holding them up as objects of con- tempt and ridicule ; and when advancing to battle, they display them before the hostile party, and accompany the exhibition by arrogant and insulting speeches. They generally consider these heads as tokens of victory ; they are brought home by the conquerors to their wives and children, that they also may have an opportunity of rejoicing with them over their fallen enemies, and they offer them to the spirits as a thanksgiving for victory. At the Bay of Islands, Hookianja, North Cape, &c., the chiefs who die (with but few exceptions) are buried unmutilated ; but at the Thames, East Cape, &c., the heads of the chiefs are generally preserved, both out of respect for the deceased, and to show to those of his relations who are absent at the time of his death. These heads are never sold, the heads of their enemies only being thus disposed of as a mark of contempt towards them. One of the heads in my possession (and of which a drawing is annexed) I purchased at the river Thames, and, what is rather unusual, was able in this instance to procure the name, rank, character, &c. of the individual, and it was procured from the chief by whom he had been slain. He was named BOLA ; his father's name was Tumau, and he was a young chief of the district of Wigato, at the river Thames. His age was supposed to be about eighteen years, and he had not long been tattooed, the whole of which process was not completed at the time of his death. He was described as being a great warrior for his age, and a very enterprising character, always endeavouring to be the first in battle, and to kill the first man, Q 2 218 Mr. Bennett on the Mode of preparing which exploits are considered among them as highly honour- able. During an engagement, he was first shot in the abdo- men by a chief named Warrinhu Eringa (who related to me some of this account), and, on falling, was finally dispatched by a blow on the head with a tomahawk ; on an examination of the side of the head, the fracture is very visible, and is of some extent. The New Zealanders care not to conceal that they are can- nibals ; they relate the atrocities connected with the practice without any appearance of shame or remorse ; they only eat, however, of the bodies of their enemies. If an enemy of rank is slain, the eyes, hands, and feet are presented to the highest chief of the conquering party, as they observe, that e with the eyes their enemy saw his adversaries, with his hands he fought, and with his feet he invaded their territory — they bore him to the combat.' There was a chief of a district in the vicinity of the river Thames, who was pointed out to me as the one who killed the noted chief named Atoi, or Pomari, and who was said, in their style of expression, to have ' eaten of his eyes, and drank of his blood."* Respecting the eating of the eyes, there formerly existed a somewhat similar custom at the island of Tahiti, from which it has been inferred, that the natives of that island were formerly addicted to the horrible custom of cannibalism : the coincidence is curious, and Captain Cook makes the following observations respecting it. ' We have great reason to believe,' he observes, ' that there was a time when they were cannibals. We were told (and, indeed, partly saw it) that it is a necessary ceremony when a poor wretch is sacrificed, for the priest to take out the left eye; this he presents to the king, holding it to his mouth, which he desires him to open ; but instead of putting it in, immediately withdraws it. This they call " eating the man,1' or " food for the chief;" and, perhaps, we may observe here some traces of former times, when the dead body was really feasted on.' Ellis observes, however, in a more recent publication (Polynesian Re- searches, vol. i. pp. 35, 357,8), that < It has been supposed that the circumstance of the priests offering the eye, the most precious part of the victim, to the king, who appeared to eat it, indicated their having formerly devoured the men they Human Heads among the New Zcalanders. 219 had sacrificed.' ' I do not,' he further observes, « regard this fact as affording any very strong evidence, although I have not the least doubt that the inhabitants of several of the South-Sea Islands have eaten human flesh. From the many favourable traits in their character, we have been un- willing to believe they had ever been cannibals ; the conviction of our mistake has, however, been impressed by evidence so various and multiplied as to preclude uncertainty. Their mythology led them to suppose that the spirits of the dead are eaten by the gods or demons, and that the spiritual part of their sacrifices is eaten by the spirit of the idol before whom it is presented. Birds resorting to the temple were said to feed upon the bodies of the human sacrifices, and it was imagined the god approached the temple in the bird, and thus devoured the victims placed upon the altar. In some of the islands, " man-eater " was an epithet of the principal deities ; and it was probable, in connexion with this, that the king, who often personated the god, appeared to eat the human eye.' Notwith- standing these judicious remarks, the coincidence is very ex- traordinary with the custom of New Zealand, where the eye is actually devoured, and where the natives are well known to be cannibals ; and what further corroborates the supposition that the Tahitans were anciently anthropophagi is, that, as the author before quoted observes, (Polynesian Researches, vol. i., p. 310,) ' the Tahitans were not altogether free from cannibalism ; and occasionally a warrior, out of bravado or revenge, has been known to eat two or three mouthfuls of a vanquished foe, generally the fat from the inner side of the ribs.' From this it would appear, that the exciting cause of- cannibalism is, both with this people and the New Zealanders, revenge : for cannibalism, the New Zealanders informed me, arises from this feeling, not from hunger; and from believing that, by eating of the bodies of the valiant, as all those are considered who die fighting on the field of battle, they become inheritors of their courage and valour. The hor- rible practice of cannibalism having been found existing in the most fertile countries, we must seek for some other motives for the custom than mere hunger ; and the above causes, as asserted by the natives, seem to be the most probable. To 220 Mr. Bennett on the Mode of preparing eat the bodies, however, hunger would be requisite, combined with the revengeful feeling : all provision being sent away from the field of battle, with the women and children, hunger becomes a concomitant with the revengeful feeling, but not the sole exciting cause. After a battle, it is customary to collect all the dead bodies of the enemy together, and the heads of those intended for preparation having been detached, are delivered to the persons who are habituated to it ; the bodies are then cut open, the viscera, &c. extracted, and the remainder cut into pieces ; they then proceed to cook and prepare the banquet — in what manner they are not particular : some make an oven and steam it, others roast on the fire, but they seldom or never eat it in a raw state ; but it is a common and general custom, on an enemy falling in battle, for his adversary, excited by the demoniacal spirit of revenge, to rush immediately towards him for the purpose of sucking the blood from his throat, before the vital spark has fled. They also dry the hands of their enemies, and fasten them near their huts, the fingers having been previously dried in a contracted form, so as to be used as hooks, on which to hang their baskets, &c. They also preserve the fat from the buttocks, and the internal fat or fare ; they melt it down by the aid of hot stones, keep it in calabashes, and eat it with their potatoes: this is more generally done when the person is a powerful chief, and they always express it as being a mark of great contempt towards him. On my asking some of those who gave me information respecting this horrible custom, how they would like to be eaten, the reply was, ' that it was no matter what was done with them after death.' On my inquiring what was done with the bones of the human bodies that were eaten, I was informed that, if those of a chief, they were preserved; those of the arms, legs, &c. being used for making the flutes named Lehu or Bulrua, others as ear ornaments, &c. ; but the bones of a common individual were thrown away. With respect to the taste of this food, they describe it as being superior to pork. Vessels are occasionally destroyed by the natives, and the crews massacred ; at one time several heads of unfortunate Europeans, who had thus been murdered, pre- served in a similar manner as among themselves, were pur- Human Heads among the New Zealanders. 221 chased and brought by a colonial vessel to Sydney, New South Wales. One of the chiefs at the river Thames, from whom I made the inquiry, whether he had ever eaten of the flesh of white men, and whether it was better tasted than that of a New Zealander, replied, that ' he had tasted of the flesh of Europeans : sometimes he found it good, sometimes bad, but generally very salt.' It is a curious circumstance that the natives of New Zealand always express a dislike to salt. It is customary, if a chief is ill, for a slave to be killed, as an offering to the spirits, but the body is not eaten ; but if a chief is slain, or deeply offended by the chief of any particular dis- trict, and his relations should have any slaves in their possession belonging to that district, they are killed and eaten from revenge. During my visit to New Zealand, in June 1829, 1 was ram- bling on shore at Wyshaki Cove, River Thames, on a botanical excursion, when, among some rushes which grew on the bor- ders of a rivulet, I observed some bones protruding, and, on a closer examination, found a heap of human bones, apparently belonging to one person. I thought there had been a cannibal banquet at this place, and I brought away several of them with me ; but on showing them to a chief, he said they were those of a person who died a natural death ; had they been those of a person who had been killed and eaten, they would not be in so perfect a state ; and on mentioning that I had found them collected together in a heap, confirmed him in his opinion. He also said of the lower jaw, that if it had been that of an enemy, it would have been cut down, and used as a fish-hook (matau). At the village of Kororadeka, Bay of Islands, which is much frequented by whalers and other vessels for refreshments, and which is situated opposite to the missionary station of Paihia, several cannibal banquets have taken place on the beach. Some of the notions which persons in this country entertain on the subject of cannibalism are very erroneous ; since my arrival in England, I have had several curious questions asked me : among numerous others this was one — Whether a child, which I brought from Erromanga, one of the New Hebrides group (where they are cannibals), could eat our food ? Sur- prised at the question, I asked why not? ' Because,' was the 222 Mr. Bennett on the Mode of preparing Human Heads. reply, ' I thought that, after having been accustomed to devour human flesh, she would not be able to relish any other kind!' It is supposed that, by purchasing the preserved heads from the New Zealanders, an encouragement is held out for them to engage in war, or to murder their slaves. This I consider erroneous. They have preserved them, from time immemorial, as trophies, and whether they are or are not purchased by Europeans, the custom will continue, until civilization has extended among these noble, but savage people. During a long stay at New Zealand (and that principally at the river Thames, where it is generally considered they might be pur- chased in some quantity), not more than six were procured ; the reason assigned for their scarcity by the natives being, that there had been lately no wars among them. In conclusion, we may observe, with Dr. Good, that ( one common character runs through savages of every kind. The empire of the heart is divided between two rival deities, or rather demons — selfishness and terror. The chief ministers of the first, are lust, hatred, and revenge — the chief ministers of the second, are cruelty, credulity, and superstition. Look through the world, and you will find this description apply to barbarians of every age and country. It is equally the history of Europeans and Africans ; of the Pelasgi, who were the progenitors of the Greeks ; and of the Celts and Scythians, the successive progenitors of the English. All the discoveries of modern circumnavigators confirm the assertion ; and though the captivating names of Friendly and Society Islands have been given to two distinct groups in the vast bosom of the Pacific Ocean, and the inhabitants in several of them have made some progress in the first rudiments of civilization and government, there is not a people or a tribe to be met with, who are yet in a savage state, that are not still slaves to their debasing and tyrannical passions*.' * Book of Nature, vol. iii., p. 280-81. 223 ON THE TRANSMISSION OF MUSICAL SOUNDS THROUGH SOLID LINEAR CONDUCTORS, AND ON THEIR SUBSE- QUENT RECIPROCATION. By CHARLES WHEATSTONE. § I- HHHE fact of the transmission of sound through solid bodies, as when a stick or a metal rod is placed at one extremity to the ear, and is struck or scratched at the other end, did not escape the observation of the ancient philosophers : but it was for a long time erroneously supposed, that an aeriform medium was alone capable of receiving sonorous impressions ; and in conformity with this opinion, Lord Bacon, when noticing this experiment, assumes that the sound is -propagated by spirits contained within the pores of the body*. The first correct observations on this subject appear to have been made by Dr. Hooke in 1667 ; who made an experiment with a distended wire of sufficient length to observe that the same sound was propagated far swifter through the wire than through the air i. Professor Wunsch, of Berlin, made, in 1788, a similar experiment, substituting 1728 feet of connected wooden laths for the wire, and confirmed Dr. Hooke's results J. * ' If a rod of iron or brass be held with one end to the ear, and the other be struck upon, it makes a much greater sound than the same stroke upon the rod, when not so contiguous to the ear. By which, and other instances, it should seem that sounds do not only slide upon the surface of a smooth body, but also communicate with the spirits in the pores of the body.' — Sylva Sylvarum, Pho- nics, § 3. ' The pneumatical part, which is in all tangible bodies, and has some affinity with air, performs, after a sort, the office of the air. Thus the sound of an empty barrel is in part created by the air on the outside, and in part by that in the inside ; for the sound will be less or greater, as the barrel is more or less empty ; though it communicates also with the spirit in the wood, through which it passes from the outside to the inside.' — Sylva Sylvarum, Phonics, § 2. f ' And though some famous authors have affirmed it impossible to hear through the thinnest plate of Moscovy glass, yet I know a way by which 'tis easy to hear one speak through a wall a yard thick. It has not yet been thoroughly examined, how far otacoustics may be improved, nor what other ways there may be of quickening our hearing, or conveying sounds through other bodiet than the air ; for that that is not the only medium I can assure the reader, that I have, by the help of a distended wire, propagated the sound to a very considerable distance in an instant, or with as seemingly quick a motion as that of light ; at least, incomparably swifter than that which at the same time was propagated through the air ; and this not only in a straight line, or direct, but in one bended in many angles.' — Preface to Hooke's ' Micrographia,' t Acad. fieri. Deutsch, abh. 1788, 87. 224 Mr. Wheatstone on the Other experiments of a similar nature were subsequently made by Herhold and Rafn*, Hassenfratz and Gay Lussacf» &c. ; but the first direct observations of the actual velocity of sound through solid conductors were made by Biot, assisted at different times by Bouvard and Martin. These experiments were made on the sides of the iron conduit-pipes of Paris, through the length of 951m. 25 ; and the mean result of two observations made in different ways gave 3459 metres, or 11,090 feet per second, for the velocity of sound in cast iron J. Previously to these last-mentioned experiments, Chladni had, in an ingenious manner, inferred the velocity of sound in different solid substances ; and his results are fully confirmed by calculations from other grounds. His method was founded on Newton's demonstration, that sound travels through a space of a given length, filled with air, in the same time that a column of air of the same length, contained in a tube open at both ends, makes a single vibration ||. His own discovery of the longitudinal vibrations of solid bodies, which are exactly analogous to the ordinary vibrations of columns of air, enabled him to apply this proposition to solid bodies, and to establish the general law, that sound is propagated through any elastic substance in the same time in which this substance makes one longitudinal vibration. In this manner he ascertained the velocities of sound in the following substances, among others : tin 7,800, silver 9,300, copper 12,500, glass and iron 17,500, and various woods from 11,000 to 18,000 feet in a second. From the experiments of M. Perolle §, it would appear that the intensity with which sound is communicated through solid matters is nearly in proportion to the velocity of its trans- mission. * Reil's Archiv fur die Physiologic, vol. iii., No. iii., p. 178. f Annales de Chimie, tome liii., p. 64. J Memoires de la Societe d'Arcueil, tome ii., p. 403. || A single vibration is here considered as the motion of the vibrating body between the two opposite limits of its excursion, and with this signification the ex- pression is adopted by Chladni. Other authors, however, regard this, with Newton and Sauveur, as a semi-vibration, and call an entire vibration the motion of the vibrating body from one limit of its excursion until it again arrives at the same limit. This difference of meaning attached to the same term has given rise to several mistakes. § Journal de Physique, tome xlix., p. 382. Transmission of Musical Sounds. 225 I 2. In all the experiments above alluded to, the sounds trans- mitted were either mere noises, such as the blow of a hammer, or, as in Herhold and Rafn's experiment, a single musical sound, produced by striking a silver spoon attached to one end of the conducting wire ; and in no case were any means em- ployed for the subsequent augmentation of the transmitted sound. I believe that, previous to the experiments which I commenced in 1820, none had been made on the transmission of the modulated sounds of musical instruments ; nor had it been shown that sonorous undulations, propagated through solid linear conductors of considerable length, were capable of exciting, in surfaces with which they were in connexion, a quantity of vibratory motion, sufficient to be powerfully audible when communicated through the air. The first experiments of this kind which I made were publicly exhibited in 1821, and notices of them are to be found in the Literary Gazette, Ackerman's Repository, and other periodicals of that year. On June 30, 1823, a paper of mine was read by M. Arago, at the Academy of Sciences in Paris, in which I mentioned these experiments, and a variety of others relating to the passage of sound through rectilinear and bent conductors *. I propose, in the present instance, to give a more complete detail of these experiments than I have yet published ; and at the same time to add what additional facts my subsequent experience has furnished me with on the same subject. | 3. Before proceeding any further, it will be necessary to make a few observations on the augmentation of sound which results from the connexion of a vibrating body with other bodies capable of entering into simultaneous vibration with it. This participation of the vibrations of an original sounding body is called resonance, or reciprocation of sound. Sonorous bodies are audible (the extent of their excursions being supposed equal) in proportion to the quantity of their vibrating surfaces. Thus, a plate of glass or metal is capable * An abridgment appeared in the Ann. de Chimie, July, 1823, and the entire paper in the Annals of Philosophy, August, 1823. 226 Mr. Wheatstone on the of producing powerful sounds "without accessory means ; but the sound of vibrating bodies of smaller dimensions, such as insulated strings, or tuning-forks, are scarcely audible at a moderate distance from the ear ; but the sounds of the latter are capable of considerable augmentation when communicated to surfaces, as when they are placed to a table, or to the sounding-board of a musical instrument. There are several circumstances which influence the inten- sity of the resonance of a sounding-board. The principal of these is the plane in which the vibrations of the sounding body are made with respect to the reciprocating surface. Thus, its vibrations may be so communicated as to be perpendicular, or normal to the surface, in which case the sound is the most greatly augmented ; or they may be tangential to, or in the same plane with the surface, when the sound is the most feeble. The first of these cases may be illustrated by placing a vibrat- ing tuning-fork perpendicularly to the surface of a flat board ; and the second, by placing it perpendicularly to one of the edges of the board. In intermediate positions — viz. when the vibra- tions are communicated obliquely to the surface — the sound will be found to have intermediate degrees of intensity. These facts, which the extensive investigations of Savart place in full evidence, being understood, the peculiarities of the sounding-boards of various musical instruments admit of easy explanation. The sounding-board of the piano-forte is better disposed than that of any other stringed instrument, as the planes of the vibrations of the strings are, on account of the direction in which they are struck by the hammers, always perpendicular to its surface. The difference of intensity when a string vibrates in this way, and when it vibrates parallel to the sur- face, is very obvious, and may be easily tried by striking it with the finger in these two directions *. There is no other in- strument now in use, in which the strings make their vibrations perpendicular to the sounding-board. * It sometimes happens, when the impulse is oblique to the direction in which the string presses on the bridge, that its plane of vibration assumes a rotatory motion; the periodical changes of intensity thus occasioned, produce an effect similar to that of the beating of imperfect unisons. This phenomenon is generally erroneously attributed by tuners to a faulty string. Transmission of Musical Sounds. 227 In the guitar, lute, &c., the strings are also parallel to the sounding-board, but the vibrations must, for the convenience of performance, be made obliquely to it. If the sides of the instrument be of inconsiderable depth, and the back be flat, the difference of intensity between the perpendicular and oblique vibrations will be very sensible. But if the sides be deep, very little difference will be perceived, as the vibrations which are tangential to the front sounding-board are perpendicular to the sides, which thus enter readily into normal vibrations ; this fact may be proved by placing the ear to the side of a guitar while a string is made to sound with its plane of vibration suc- cessively parallel and perpendicular to it. In some instru- ments, as the lute, mandoline, &c. the back is polygonal or curved ; by this construction a considerable portion of the re- sonant surface enters into normal or nearly normal vibrations when the strings are struck obliquely to the principal sounding- board. These laws are not so immediately applicable to the violin, and other instruments of the same class ; an extensive series of experiments will yet be necessary to enable us to account for the peculiarities of their forms, their various curvatures, and the functions of that irregular conductor, resting on the sound- ing-board at two points only, which in these instruments is called the bridge. The investigations of Savart still leave much to be desired on this head. In no instrument are the strings perpendicular to the sound- ing-board ; for in such case, however a string were made to vibrate, its communicated vibrations would be tangential. But they are sometimes placed obliquely, as in the harp, and then the same changes of intensity may be observed as when the strings are parallel to the board ; for if the plane of their vibrations coincide with that of the inclination of the board, the commu- nicated vibrations of the board will be oblique to its surface, and the intensity will be at its maximum ; but if they be per- pendicular to this plane, the communicated vibrations must be tangential to this surface, and consequently the intensity will be at its minimum. Besides the proper adaptation of sounding-boards, there are other circumstances on which the tones of a stringed instrument 228 Mr. Wheatstone on the materially depend ; one of the most important of these is, the proper dimensions of the volume of air contained within the sides ; the laws of these resonant cavities have occupied the attention of Savart, but the obvious use of the bars placed within these cavities to divide the mass of air, and thus to enable it to vibrate more readily in separate portions, seems to have escaped his notice. §4. In the piano-forte, the guitar, &c., the ends of the strings are not in immediate contact with the sounding-board, but they rest on bars of wood, which are called bridges, through which the vibrations are communicated to the board. In these in- struments the bridge is usually about half an inch in height, and in the violoncello does not exceed three inches. To as- certain how far the distance might be extended between the string and the sounding-board of a piano-forte without injury to the tone, I substituted a glass rod five feet in length for the bridge, and by placing at its end a string stretched on a steel bow, I found that the sound of the string was as distinctly audible as when it was immediately in contact with the board ; a tuning-fork placed at the end of the rod gave the same result. These experiments, which were the first I made on the subject, and which suggested all the subsequent ones, have been repeated in the theatre of the Royal Institution on a larger scale. A series of connected deal rods, forty feet in length, was suspended so as to extend, in a straight line, ob- liquely from an open window of the cupola, to within a short distance of the floor of the room ; on the upper end of this conductor, an assistant placed the stem of a vibrating tuning fork ; when no sounding-board was placed at the lower extre- mity of the conductor, no sound was heard, but it became powerfully audible the instant the communication was made : this experiment was repeated with different acute and grave toned tuning-forks, employed both in combination and in suc- cession. Tuning-forks are the most convenient instruments for making experiments on the transmission of sound, because their vibra- Transmission of Musical Sounds. 229 tions are almost inaudible by themselves, and only become strongly audible when augmented by resonant surfaces. The vibrations of the sounding-board of any stringed in- strument may be communicated in the same manner as those of a string, or of a tuning fork, to a distant sounding-board by means of a metallic, glass, or wooden conductor ; but in this case it is necessary to prevent the original sounds from being heard through the air, otherwise the communicated sounds will not be distinguishable from them. This may be effected by placing the originally vibrating, and the reciprocating instru- ments in different rooms, and allowing the conductors to pass through the floor or wall separating the two rooms. In the passage of the conducting- rod or wire through these partitions, care must be taken to prevent its touching their sides ; for this purpose, a tin tube, covered at its two ends with leather, or India rubber, may be inserted in the partition, and the conductor be made to pass through holes in these coverings, so as not to touch the side of the tube. A square piano-forte is a very convenient instrument to employ in these experiments. If the sound is to be trans- mitted upwards, nothing more is requisite than to open or remove the lid of the instrument, and to allow the conductor to rest upon the sounding-board. A metallic wire is not suffi- ciently rigid to support itself thus without bending ; a rod of some straight-fibred wood, as lancewood or deal, is therefore belter adapted for this form of the experiment ; the lower end of the rod must be reduced in thickness, so as to allow it to pass between two adjacent strings ; and the best place to make the contact will be found to be about a quarter of an inch from the bridge, among the middle notes, and on the side occupied by the unvibrating portions of the strings. The reci- procating instrument in the room above, may be a guitar or any other similar instrument, or a harp; in which latter case, the rod may be brought in contact with the inner surface of the belly of the instrument, through one of the apertures of the swell. These were the forms under which the experiments have been repeated at the Royal Institution. 230 Mr. Wheatstone on the If the sounds of the piano-forte are to be transmitted down- wards, a brass wire, about the thickness of a goose-quill, will suffice for the communication, as the weight of a reciprocating instrument suspended from it below will keep it sufficiently straight. To bring the conducting-wire into contact with the under surface of the sounding-board of the piano- forte, an aperture must be made in the bottom of the instrument imme- diately below the intended point of contact ; and to ensure a perfect connexion with the sounding-board, it is advisable to furnish the wire with a shoulder just below its entrance into the aperture, and to occasion an upward pressure on this shoulder, by a piece of leather stretched on a ring (as in the insulating-tube above described) and placed at the end of a strong steel spring ; the other end of which is screwed firmly to the bottom of the instrument. To assist in supporting the wire, another shoulder may be made on it, so as to rest upon the upper covering of the insulating-tube which passes through the floor ; and the reciprocating instrument may be suspended by inserting the end of the wire into the sounding-board, and then securing it by a nut and screw on the opposite side. The form of the resounding instrument is a matter of choice ; but, in order to obtain the freest and loudest tones, it is requisite to have the principal vibrating surface perpendicular to the con- ducting-wire. It is instructive to observe the gradual changes in the intensity and the quality of the transmitted sounds, when the sounding-board is made to pass through the various degrees of obliquity from a perpendicular direction to the con- ductor, until it is in the same plane with it; or, to employ Savart's language, as the communicated vibrations change from normal to tangential ; in the latter case, the sounds have a subdued, and what is ordinarily called a metallic quality. In the first public experiments I made in 1821, the recipro- cating instrument, which was the representation of an ancient lyre, was so constructed as to produce tangential vibration ; the tones were consequently far inferior to what I have since been able to produce. The transmitted sounds are not sensibly impaired when the wire is separated at several places, and the disunited parts fastened together by mechanical contact ; the annexed wood-cut represents the divisions of the conducting- Transmission of Musical Sounds. 231 wire, which I found it convenient to make in the original form of the experiment, for the sake of portability and facility of removal ; but, if the apparatus be intended as a fixture, it will be easier and better to employ but one length of wire. The wire consisted of four portions : the first part touched the sounding-board of the piano-forte, and reached half-way to the floor; the second passed through the insulating-tube in the floor, and terminated when it reached the ceiling of the VOL. 1 1. Nov. 1831. 232 Mr. Wheatstone on the room below in a hook ; a third part was suspended from this hook by a loop ; and the fourth, after identifying itself with one of the apparent wires of the lyre, passed within the in- strument, and was ultimately fixed, at its lower end, to the point marked at the end of the dotted line on the sounding- board ; each of the disunited parts were allowed to overlap each other at a and b, and were fastened together by means of a clamp with a screw-nut. The whole apparatus thus pre* pared may be easily removed ; the clamps being unscrewed and the resounding instrument removed, the lower wire must be unhooked from the ceiling, the hook unscrewed, and the middle wire withdrawn from the insulating-tube : the time for fixing or removing the apparatus need not exceed a few minutes. From what has preceded, it will be obvious in what manner two square piano-fortes or two harps may be so connected as mutually to reciprocate each other's sounds ; by such an arrangement,, two performers in different rooms may play a duet together to two distinct audiences, or one may echo the performance of the other. If the transmission is required to be horizontal, i.e., between two rooms on the same floor, cabinet piano-fortes must be employed. The sounds of an instrument may be at the same time trans- mitted to more than one place ; for instance, communications may be made from a square piano-forte to a resounding in- strument above, and to another below; and the communi- cation may be even continued through a series of reciprocating instruments. If the instruments be not in adjacent rooms, but be further removed from each other, a person in the inter- mediate room, through which the conductor passes, will hear no sound but what is communicated by the ordinary means. Hence it would be possible to extend a horizontal conductor through a series of rooms belonging to different houses, and (provided the instrument connected with one of its extre- mities be constantly played upon) to hear at pleasure the performance in any of these rooms, by merely attaching a reciprocating instrument to the conductor; on removing this instrument, the sonorous undulations would pass inaudibly Transmission of Musical Sounds. 233 to the next apartment. These observations will equally apply to the transmission of other musical sounds, which will be hereafter noticed (§6, 7). §6. The transmission of the sounds of those stringed instru- ments which produce sustained sounds, as the violin, violoncello, &c., is equally effective. The conducting-rod may be applied either to the back or the front of the instrument; no precise directions can be given with respect to the points at which the contact should be made ; but, in general, the effect has appeared to me better when the end of the conductor has not been too far removed from the situation of the sound-post. §7. I have been able to effect the transmission of the sounds of reed wind-instruments through solid conductors as perfectly as that of instruments dependent on the vibrations of sounding- boards. In the clarionet, or any other reed instrument, the column of air and the vibrating tongue (or reed) mutually influence each other in such a manner, that whether the sounds be communicated to the atmosphere from the column of air, or to a solid conductor from the vibrating tongue> the quality (timbre) of the sound undergoes no change. To connect the conducting wire, which may be of brass, and about a tenth of an inch in diameter, with the tongue of the clarionet, the end of the wire must be bent for about a quarter of an inch, and then filed flat on both sides. This flattened end must be fastened to the fixed end of the tongue by the silk wrapping which usually fastens the tongue only, and the angle of the bend be adjusted so as to suit the position of the performer. If the sound is to be transmitted downwards, the embouchure of the clarionet must be placed in the performer's mouth in the usual way, viz. the tongue of the reed resting on the under lip ; but if the sound is to be transmitted upwards, the performer must play, as some eminent masters of this instrument do, with the tongue applied to the upper lip. For the bassoon or the hautbois, it is equally convenient to the B2 234 Mr. Wheatstone on the performer, whether the wire be applied to the reed above or below. The resounding instrument may, as in the experiments above detailed, be either a harp, a piano-forte, or a guitar. It is a singular effect to hear the sounds of a wind-instrument thus reproduced by a sounding-board. §8. The experiments I have made with respect to other classes of wind-instruments have not been equally successful. It is not possible to communicate the vibrations of the air to a solid conductor without an enormous loss of intensity : if, however, the intermediation of other bodies which enter readily into vibration, from the agitations of the air, be employed, the transmission may in some measure be effected. Thus, if the end of the conducting-wire be placed in the most strongly vibrating part of the column of air in a flute, there is but little perceptible transmission of sound ; but if the wire touch the side of the instrument, it will more readily transmit the sounds, as the side is susceptible of entering into vibration. Even in this latter case, the sounds are scarcely audible, unless the ear be held close to the resounding instrument. In a similar manner, the sounds of an entire orchestra may be transmitted, viz. by connecting the end of the con- ductor with a properly constructed sounding-board, so placed as to resound to all the instruments. The effect of an ex- periment of this kind is very pleasing; the sounds, indeed, have so little intensity as scarcely to be heard at a distance from the reciprocating instrument ; but on placing the ear close to it, a diminutive band is heard, in which all the instru- ments preserve their distinctive qualities ; and the pianos and fortes, the crescendos and diminuendos, their relative con- trasts. Compared with an ordinary band, heard at a dis- tance through the air, the effect is as a landscape seen in miniature beauty through a concave lens, as compared with the same scene viewed by the ordinary vision through a murky atmosphere. Transmission of Musical Sounds. 235 §9. In the preceding experiments on the transmission of sound through solid bodies, the conductors have been represented as straight; but, though sound is transmitted the more readily through straight conductors, it will yet pass, though with diminished intensity, through rods with angular and curved bendings. If a vibrating tuning-fork be placed at one end of a straight brass rod, the other end of which rests perpendicu- larly upon a sounding-board, the vibrations will, in accordance with what has been above stated, be powerfully transmitted ; on gradually bending the rod at any part of its length, while the vibrations of the tuning-fork are kept in the same plane with the angle of the bent rod, the transmitted sound will pro- gressively decrease in intensity, and will be very feeble when the angle has become a right one : as the bending is continued so as to make the angle between the two parts of the rod more acute, the intensity of the sound will increase in the same order in which it had before diminished ; and when the two parts of the rod are nearly parallel, the sound will be nearly as loud as when the transmission was rectilineal. If, during the gradual bending of the rod, the plane of the vibrations of the tuning-fork be perpendicular to the plane of the angle made by the two parts of the rod, the same changes will be observed, but in a more obvious manner, than in the former case ; and when the angle becomes a right one, the sound will be scarcely perceptible. At intermediate inclinations of the two planes, the gradations of intensity, occasioned by the bending of the rod, will be found to be intermediate. The changes of intensity dependent on the variation of the angle of the two planes may be instructively shewn by bending the rod permanently to a right angle, and placing, as before, the stem of a tuning-fork so as to form the prolongation of one of the parts of the rod, the other part of the rod resting on the sounding-board. On gradually turning the tuning-fork round the axis of its stem, without inclining it to the rod, the plane of the vibrations will assume every angle with respect to the plane in which the two parts of the rod is bent. During the revolution it will be observed, that when the planes coincide 236 Mr. Wheatstone on the the intensity will be at its maximum, and when they are per- pendicular to each other, at it's minimum; thus, supposing the sound to commence when the two planes are parallel, it will gradually diminish until they make an angle of 90° ; it will then increase through the same changes of intensity, in an inverted order, until it acquires its maximum at 180°; it will again decrease between this and 270°, and increase until it arrives at its first position at 0°. If the stem of the tuning- fork be placed perpendicularly on the side of a conducting- rod resting on a sounding-board, the same phenomena may be observed ; the stem of the tuning-fork is, in fact, a short con- ductor, forming a right angle with the rod. Were it necessary for the transmission of sound that the undulations should propagate themselves only rectilinearly, it is obvious that they would not pass through a bent rod ; and, on the other hand, had they the property of diffusing themselves equally in all directions, we should not observe any differences of intensity in the experiments above noticed. These expe- riments lead us to conclude, that sound diffuses itself in all directions, though unequally ; that it is communicated more readily in the plane in which the original vibrations are made, and with the greatest degree of intensity in the direction of these vibrations. § 10. In most of the experiments relating to the transmission of the sounds of musical instruments, which I have in the preced- ing paragraphs detailed, the conductor has been represented as receiving its impulses from a surface vibrating normally, to which it was perpendicularly attached ; the communication was consequently effected by longitudinal undulations in the conducting wire. But if, while the conductor retains its posi- tion, the surface were' to vibrate tangentially or obliquely, the communication would be effected by transversal 'or oblique undulations. In practice it is preferable to employ the longitudinal undu- lations for the purpose of transmitting musical sounds to a Distance; for, firstly, the transmission is more efficacious; and, secondly, 'the transverse undulations have a great ten Transmission of Musical Sounds. 237 dency to communicate themselves laterally from the conductor to the surrounding medium, and thereby to become audible without the assistance of a reciprocating instrument. This lateral dispersion is scarcely observable with small conductors but is very obvious when a rod of considerable diameter is employed. I had an opportunity of observing this fact while repeating some of the preceding experiments at the Royal Institution. A square piano-forte was placed in the apartment beneath the lecture-room ; and a conductor, placed perpendicularly to its sounding-board, passed through the floor separating the two rooms, but no reciprocating sounding-board was placed at its upper end. By this arrangement, longitudinal undulations were communicated to the conductor ; and, whether this was a brass wire one-tenth of an inch in diameter, or a square deal rod half an inch thick, the insulation appeared to be equally perfect. But it was not so when the conductor, instead of being placed on the sounding-board of a piano-forte, was made to rest on the top of the bridge of a violin, and the strings, put into vibration by drawing a bow across them, communicated transverse vibrations to the conductor ; it was now observed, that the metal wire insulated the sound tolerably well, but that when the wooden rod was employed, the sound commu- nicated to the air from the entire surface of the portion of the rod above the floor, was nearly as loud as if a sounding-board were placed at its extremity. §n. I have in this paper given the general results of a variety of experiments made at different and distant periods during the last ten years ; but they are far from forming so complete a course as I have been desirous of making. To extend these experiments much farther would be attended with some dif- ficulties :,but as the velocity of sound is much greater in solid substances than in air, it is not improbable that the transmis- sion of sound through solid conductors, and its subsequent reciprocation, may hereafter be applied to many useful pur- poses. Sound travels through the air at the rate of 1142 feet in a second of time ; but it is communicated through iron wire, 238 Mr. Wheatstone on the Transmission, fyc. glass, cane, or deal-wood rods, with the velocity of about 18,000 feet per second, so that it would travel the distance of 200 miles in less than a minute. When sound is allowed to diffuse itself in all directions as from a centre, its intensity, according to theory, decreases as the square of the distance increases ; but if it be confined to one rectilinear direction, no diminution of intensity ought to take place. But this is on the supposition that the conduct- ing body possesses perfect homogeneity, and is uniform in its structure, — conditions which never obtain in our actual experi- ments. Could any conducting substance be rendered perfectly equal in density and elasticity, so as to allow the undulations to proceed with a uniform velocity without any reflections or interferences, it would be as easy to transmit sounds through such conductors from Aberdeen to London, as it is now to establish a communication from one chamber to another. Whether any substance can be rendered thus homogeneous and uniform remains for future philosophers to determine. The transmission to distant places, and the multiplication of musical performances, are objects of far less importance than the conveyance of the articulations of speech. I have found by experiment that all these articulations, as well as the musical inflexions of the voice, may be perfectly, though feebly, transmitted to any of the previously described reciprocating instruments by connecting the conductor, either immediately with some part of the neck or head contiguous to the larynx, or with a sounding-board, to which the mouth of the speaker or singer is closely applied. The almost hopeless difficulty of communicating sounds produced in air with sufficient intensity to solid bodies, might induce us to despair of further success ; but could articulations similar to those enounced by the human organs of speech be produced immediately in solid bodies, their transmission might be effected with any required degree of intensity. Some recent investigations lead us to hope that we are not far from effecting these desiderata; and if all the articulations were once thus obtained, the construction of a machine for the arrangement of them into syllables, words, and sentences, would demand no knowledge beyond that we already possess. 239 ON THE INFLUENCE OF THE 'SENSE' OF MUSCULAR ACTION IN CONNEXION WITH VISION. BY ALEXANDER SHAW, ESQ. ^PO those philosophers who have studied the subject of sensation, the organ of vision has ever been the most attractive ; and yet the opinions of men, whose attainments we must respect, differ very widely as to the mode of opera- tion of this external organ of sense. Dr. Brewster, in his « Treatise on Optics,' which is the latest publication on this subject, has introduced an explana- tion of the problem — Why an inverted image on the retina should give us the idea of an erect object. This question, as he himself has remarked, has been a frequent cause of per- plexity to the learned ; but I am of opinion that no theory of vision can be admitted to be correct, which does not afford a satisfactory explanation of it. This problem involves certain physiological principles, which are not generally understood, but upon which the doc- trines of perception through the organs of the senses, espe- cially the eye, have the most intimate dependence. As the solution, which Dr. Brewster has adopted, is unconnected, and, indeed, altogether at variance with these, it becomes ne- cessary to examine it with care ; and I think it can be shown, notwithstanding the confident tone in which he has expressed himself, and the high authority which he deservedly holds in questions of optics, that the explanation which he has offered is liable to many powerful objections. It is the more im- portant to undertake this examination, since the view which he has presented may be considered as that which generally prevails. It is the same explanation which was originally pro- posed by Dr. Porterfield in the ' Medical Essays,' and Dr. Reid, when treating of the mode of operation of the organ of vision in his ' Inquiry into the Human Mind,' has explained it upon the same grounds. These writers have all agreed in representing that the idea of the ' direction ' in which objects are seen is obtained imme- diately from the retina or nerve of vision. They suppose that this nerve can convey to the mind a sensation of the course in 240 Mr. Shaw on the ' Sense* of Muscular Action which the rays have proceeded from the object to impinge upon it ; or, in other words, that the retina can receive an impression, not only of the object, but of the direction in which the object is presented to it. Founding upon this as a true position, they find it easy to frame what they consider to be a just explanation of the problem. In an inverted image, they assert, the retina does not convey the impression of its parti- cular parts being inverted ; but each point in the image is judged to be in the direction in which the rays have proceeded in falling upon it; the uppermost pencil of rays from the object, falling upon the lowest part of the image, gives the sensation of its proceeding from the highest part, and consequently makes that part appear to be at the top, instead of at the bottom ; and so, they say, it holds with regard to the lowest rays and all the others. To use Dr. Brewster's words, the retina ' sees along the lines of visible direction ; ' that is, the lines which lead from the image in the direction of the object. Such is the leading proposition on which the whole theory is rested. But it is surely an error to assume that the retina possesses such a power as is here attributed to it. If we ask — What is the meaning conveyed by the words ' visible direction* ? — it will be seen, on reflection, that they include something more than a simple sensation obtained through an organ of sense. To acquire the idea conveyed by the term ' direction ' alone, it is necessary that there should be a comparison ; that is to say, an operation of the mind itself. We can only form the idea of the particular quarter or situation in which a body is placed, by informing ourselves of its position in regard to another, which has been previously fixed upon as the standard of our comparison. To say, then, that our knowledge of * di- rection ' can be obtained at once, and can be conveyed to the sensorium like an impression through the optic nerve, is to employ the term in a vague and loose manner, which must necessarily lead into error. It is contrary to all analogy to attribute to a single nerve, as the optic, the possession of such incongruous powers as this theory assumes. Allowing that the idea of ' direction ' could be conveyed to the mind through the medium of a nerve, it would follow, if this theory were correct, that the optic nerve was not only sensible of the relative position of an object, but in connexion with Vision. 241 that it had, at the same time, the sensation of the variations of light which distinguish that object from others placed around it. The usual expression of Dr. Brewster, that the image art the retina is ' seen along' a certain line, implies this :-for these two words signify that the retina, besides discovering that the object is red, blue, or yellow, determines that it is placed to the right or to the left, or above or below, and also the exact line or degree in which it is so placed. The main error, which has misled the numerous writers who have treated of this question, and which has created the degree of puzzle that seems always to have been attached to it, may be traced to this — that they have invariably sought to solve the problem by a reference to the functions of the optic nerve alone ; they have looked upon the globe of the eye and this nerve as constituting the entire instrument of vision ; without taking into consideration the apparatus of muscles, and their nerves, which, under the guidance of the will, move and direct the eyeball from point to point. It can only have been from taking this partial view of the organ of vision that they could attribute to the optic nerve such complicated and inconsistent functions as those which have been bestowed upon it. The explanation of the problem — Why an inverted image should give the idea of an erect object, which has been adopted by Dr. Brewster, is founded upon the law which has beeri called the e law of visible direction.' This supposed law, as the words themselves imply, includes the opinion that seeing and the power of distinguishing the direction of objects are possessed by the retina together ; and the following passage, taken from the * Treatise,' will serve to exhibit the nature of the proofs Upon which it rests. * On the Law of Visible Direction. — When a ray of light * falls upon the retina, and gives us vision of the point of an 1 object from which it proceeds, it becomes an interesting ques- ' tion to determine in what direction the object will be seen, 4 reckoning from the point where it falls upon the retina. In 1 fig. 142, let Fbe a point of the retina, on which the image of 4 a point of a distant object is formed by means of the crystal- 1 line lens, supposed to be at,L' L. Now the rays which formed 242 Mr. Shaw on the < Sense ' of Muscular Action ' the image of the point at F, fall upon the retina in all possible * directions from L/ F to L F ; and we know that the point F is * seen in the direction F C R. In the same manner the points '//' are seen somewhere in the directions /' S,/T. These * lines, F R, /' S, / T, which may be called the lines of visible S. K T T T ' direction, may either be those which pass through the centre * C of the lens L/ L, or, in the case of the eye, through the centre ' of the lens, equivalent to all the refractions employed in pro- ' ducing the image ; or it may be the resultant of all the direc- ' tions within the angles L/FL, I/yL; or it may be a line ' perpendicular to the retina at F/'/. In order to determine ' this point, let us look over the top of the card at the point of * the object whose image is at F, till the edge of the card is just * about to hide it ; or, what is the same thing, let us obstruct all * the rays that pass through the pupil excepting the uppermost « R L' ; we shall then find that the point whose image is at F5 4 is seen in the same direction as it was seen by all the rays I/ F, « C F, L F. If we look beneath the card in a similar manner, * so as to see the object by the lowermost ray R L F, we shall * see it in the same direction/ It is remarkable that Dr. Brewster, in conducting an argu- ment of this nature, should have fallen into two such errors as are here exhibited. 1. He endeavours to demonstrate how the retina can dis- cover the relative direction of an object, and yet he omits altogether to present any second object or image to our notice. In each of the three instances which he has given, he has confined his attention solely to the object whose direction forms the question at issue, or to the rays which come from it, or to in connexion with Vision. 243 the image formed by it upon the retina. But it is obvious that from such a mode of proceeding no conclusion could ever be drawn. There ought to have been some standard, or some fixed point introduced, by which to calculate the comparative direction of the object ; or to enable us to estimate the truth of the demonstration, by contrasting one line of visible direc- tion with another. 2. But it is in his experiment that the most remarkable error is found: indeed, the conclusion which he has drawn from it must have somewhat startled the reader. He affirms that if the rays RC RL, proceeding from a distant point, be cut off by a card (which may be represented by AB), and the n ray RL', alone enters within the eye, the image F will be seen along the line FCR. But how can this, by any possibility, be the case ? Is it not obvious that the card AB totally obstructs vision in that direction ? if we * see along ' the line, it can only be by seeing through the card ! An explanation seems to be required how Dr. Brewster could have been brought to make so extraordinary a statement. The error can only have been occasioned by his proceeding on a wrong path in making this inquiry. Unexpected conclusions are often forced upon us in the study of mathematics ; and even when a strict course of in- ductive reasoning is pursued in physical subjects, the results are often strange, and apparently paradoxical: so that we need not be surprised that a learned philosopher should occasionally yield his assent to a proposition which an uneducated person, guided solely by his common sense, would at once reject. But it does not appear that the conclusion which Dr. Brewster has drawn, in the present instance, is to be justified on the grounds of its being founded either on mathematical demonstration, or on correct induction. In explaining the result of his experi- ment, he has mixed up with the facts a bare and unwarranted assumption regarding the power which belongs to the retina. 244 Mr. Shaw on the ' Sense ' of Muscular Action If the experiment with the card be made as he has directed, it will be found to be true that the image F retains the same position, whichever ray, proceeding from the object, is per- mitted to enter the eye ; and it appears in the same place, whether all the rays, or only one be admitted. But this by no means leads to the conclusion that the direction of the object is ascertained by the retina pursuing the object along any par- ticular line. It shows only, that the same sensation is excited whether a ray falls obliquely upon the retina, either from above or from below, or falls upon it in a perpendicular line ; and that, therefore, no contrast can be made between them. It ought rather to have been noticed that all the rays from the external object concentrate towards a single point in the retina F — that each individual ray, however separated from the others in its course, must proceed from the same point in the object, and affect the same spot in the retina — that, consequently, no difference in the sensation is to be expected — and that it is altogether futile to look upon the direction of the several rays as leading to any knowledge of the place of the object. It is not easy to understand what is meant by the expression 1 seeing along ' lines, when these lines stretch outwardly from the retina through the humours of the eye and through the atmosphere. Dr. Porterfield has said that ( by virtue of a connate and immutable law, the mind traces back its own sen- sation, and sees every point of the object, not in the sensorium or retina, but without the eye, in those perpendicular lines,' which Dr. Brewster has called « the lines of visible direction.' This is supposing us to possess a power which reaches far beyond where the optic nerve is present to exercise it. It is also presuming that the mind has a consciousness of the out- ward object, distinct from that sensation which is conveyed by the image formed upon the nerve. But it may be asked, how is the consciousness of the object being external obtained ? — how do we acquire the knowledge of the simple fact, that the body, whose image is painted in the interior of our eye, is exterior to us ? It is not through the medium of the optic nerve alone that this information is ob- tained. Our sole knowledge of the existence of an external body, so far as the nopticerve is concerned, is acquired through in connexion with Vision. 245 the rays which emanate from it. These rays, being reflected and dispersed to a distance, according to a law of nature, from all the surfaces of the body, pass into the eye, and form upon the retina an exquisitely minute image or copy of the object. Now it is this image alone which gives rise to the impression of the object in the mind. The outward body itself does not directly excite the nerve : we have to rely for the correctness of our knowledge respecting it, upon the image, formed by the rays, being a faithful representation of it. As the image, there- fore, is at a distance from its original, and as it is perfectly dis- tinct from it, how do we learn to associate it with the external object ? — how do we discover that it is not an ocular spec- trum, or a mere phantasm, that we see ? for it is known that an impression may be made upon the retina, and remain there even while the object is removed altogether from our presence. We can only be assured that the image represents an object which is not placed within the eye, but is external to our body, by calling in the assistance of, at least, one other sense : more of these being brought in as evidences may strengthen our conviction ; but one in addition is absolutely necessary. We have the means of ascertaining the fact which we desire, in the muscular apparatus that always accompanies the posses- sion of an organ of vision. The muscles have the power of turning the eyeball either towards the object or in a contrary direction. Of this we are conscious. Now, it appears to be a simple conclusion to arrive at — that the object must have a separate existence of its own, and distinct from the eye which perceives it, — when, in order to see the same object, we invariably find that it is necessary to exercise the muscles in a particular manner. We know that, if the body presented to our sight be in motion, as a bird flying through the air, we must follow it with our eyes, making fresh efforts to keep them in the direction of its flight, other- wise it will disappear. If the image were a mere spectrum, as that produced by looking at the sun, it would present itself in whichever direction we happened to turn our eyes. Hence it follows that, even without calling the sense of touch or any of the remaining senses into operation, but depending upon the knowledge acquired from merely shifting the eye about, we 246 Mr. Shaw on the f Sense"* of Muscular Action become convinced that the body whose image is in the eye exists externally. To 'trace' or 'see along' aline, as the expression is used, includes the opinion that the object is placed externally ; it likewise includes the idea of guiding or directing the eye ; and, in addition to these, it implies the ex- istence of a coloured image painted upon the retina. The notion conveyed by these words is, therefore, most compli- cated ; and they ought never to have been applied, as has been done, in speaking of the functions of a single nerve. Another inconsistency in the theory may be noticed. The theory rests upon the supposition that the retina can distin- guish the direction of the object by seeing along lines which lead from the image to the external body. But it is incom- prehensible how the nerve, which is seated at the bottom of the eye, should be able to ascertain, by itself, the direction of rays or lines which terminate in it. These rays of light are only sensible when they arrive at that point in the surface of the retina which is their final destination ; and they are not recognizable by any other nerve of sense besides the optic nerve. Now, according to the most elementary definitions in mathematics, when we desire to learn the direction of a line, it is necessary that two points in it, at least, should be made known ; but, according to the theory, it is the single point alone which terminates the ' line of visible direction ' that is made sensible. If we could conceive that the line, in passing through the anterior surface of the eye, caused a sensation of the particular spot in the cornea where it entered, we might then have two points presented to the mind, by which to esti- mate the direction of its passage from the object to the retina: but, without such a second point, it appears quite impossible to ascertain its direction. The question as to the manner in which the idea of the 'direction' of objects is obtained, is to be approached in a very different way than by attending to the rays which proceed from them : it requires a more complex operation of the senses to acquire this knowledge of surrounding objects than has been conceived. We have already seen that, in order to ascertain the simple truth that an object is situated exter- nally, something more is necessary than a mere impression in connexion with Vision. 247 made upon the optic nerve ; and the same will be the case, it is natural to conclude, if we seek to discover its exact place in the external world. When we desire to find out the ' direction' of a body, our true purpose is to ascertain what is its position in relation to other bodies or to some fixed standard. It is sufficiently obvious that the object itself, if it were altogether detached from surrounding bodies, could never present to the mind this idea. To entertain the conception implied by the term ' direction,' it is required that other objects be presented to the sight besides that which is under our particular view ; and to institute the proper comparison, or to form the neces- sary calculation, it is as indispensable that the sensations of these neighbouring objects should be communicated to the mind as that the sensation of the object itself should be so presented. However varied the direction of the rays proceed- ing from a single object may be when compared with one another, no reasoning upon them can ever acquaint us with the relative position of that body to another, whose rays are not given. Dr. Brewster has forgotten to supply any second body, or to represent its rays, although to establish a ' line of visible direction' the existence of some standard of comparison is necessarily implied. When an object is presented before the eye, the surface of the retina is not occupied with it alone, but the whole sur- rounding scene, everything which is near it and can be included within the field of vision, is represented upon the nerve at the same time. Now, these are so many impressions by which the mind can judge of the relative position of objects ; and so long as these find admission into the eye, data shall not be wanting for instituting the necessary comparison. If a diagram be drawn, representing the surrounding objects and their images falling upon the retina, it will be easy to understand how the mind acquires the knowledge of the direction of each of them. We may make the diagram correspond with the experiment of Dr. Brewster, as it will serve as well as any other to demon- strate what is required. The card D E being placed before the eye, may prevent objects situated in that direction from casting their images upon the retina ; but, according to the terms of the experi- Voi.. II. Nov. 1831. S 248 Mr. Shaw on the * Sense* of Muscular Action merit, it does not interfere with the ray R L'. This ray being admitted, is refracted to the same point, F, in the retina, to which all the other rays, if they had not been shut out, would K also have concentrated. The ray R I/ being allowed to enter the eye, there is no reason why objects placed above the card should not also have their images represented upon the retina. Let 6 and a be such images, formed by the rays B L, A L. It is obvious that these preserve the same relation to the image at F as they did before the card was used. Now, the true explanation of our seeing this, or, in other words, of our ascer- taining any thing respecting the position of F, is this : there is, first, an impression of the image F conveyed through the optic nerve to the sensorium ; then the image b is presented to it ; and, in succession, the image a comes before it, — a pro- cess of comparison, which the mind alone can perform, is in- stituted between these various images, and the result is the knowledge of the relative direction of F to 6 and a. It is thus that the surrounding bodies, as well as the parti- cular object of sight, require to be included within the sphere of observation, in order to obtain the idea of ' direction/ As to the intermediate process by which these objects are succes- sively presented to the mind, this is a question which em- braces subjects of the highest interest. I would remark, in the first place, that the eye is not a fixed and motionless instrument, and the retina is not possessed of an uniform degree of sensibility throughout all its surface, both' of which things the theory which I have been considering would seem to imply. The retina has one spot in its surface, in connexion with Vision. 249 situated in the axis of vision, which is more acutely sensible to the rays of light than any other part; and the eyeball is admirably provided to turn and present its transparent surface so that it may catch the impressions of objects upon this spot. It is only when images fall upon this part of the retina that the mind is satisfied, or that a perfect sensation is obtained ; and the power of guiding the eye with this intention, whether it be through the motions of the body or of the head, or is produced directly by the action of the muscles of the eye, is as necessary to the perception of the direction of the things around us, as the groping about with the hands is to a blind person, to enable him to. find his way through the confused furniture of a room. We are sensible of this searching motion of the eye, made in preparation for distinct vision ; and it is by calculating the extent of this motion that we estimate * direction.' In common language we are accustomed to speak of ' direct* ing' the eye : it is allowed also, that it is by a voluntary act that we accomplish this ; but it is not so generally conceded that the exercise of the muscles, by which the eye is moved, communicates a distinct sensation to the mind ; and yet it forms an important part in the process of vision. When an astronomer directs his telescope to the heavens, he is aware that his instrument combines in it two separate means of ac- quiring the knowledge which he seeks. By the apparatus of lenses or mirrors inclosed within the tube, he ascertains the magnitude, brilliancy, or colour of the star ; but it is by a perfectly distinct apparatus that he determines its place in the heavens. He consults, for this purpose, the external parts of his instrument, such as the various levers, screws, and joints by which the tube is revolved ; and it is by looking to the scale attached to his telescope, that he is informed of the exact bearing or of the direction of the particular star. Now the outward apparatus of muscles by which the eyeball is directed in vision, is surely, in an inquiry of this kind, deserving of at- tention. There is a sensibility resident in the muscles which gives token of the degree of their contractions ; and it is by attending to these impressions, like looking to the scale of the telescope, that we become conscious of the direction of objects. S 2 250 Mr. Shaw on the ' Sense ' of Muscular Action This sensibility to the exercise of the muscular frame is independent of sight, or any of the other organs of the senses ; it is altogether a distinct source of sensation to the mind. If a person were blind, or completely isolated from all out- ward objects of sense, he would still be sensible of the motions of his arms, or of his body, or of his eyes ; and if a standard of comparison could only be communicated to him, he would be able to tell in which direction and to what extent he moved them. Although it has been only lately recognized that a * muscular sense ' exists in the body, yet it appears to be as distinctly one as any of the five senses, smelling, seeing, hearing, taste, or touch. Anatomy discloses to us that nerves whose office it is to convey sensations merely, and which are incapable of influencing the muscles to contract, are distributed with profusion to all the voluntary muscles throughout the body. These sensitive nerves of the muscles^ it has been con- cluded by Sir Charles Bell, convey to the brain the conscious- ness of the contraction of the muscles which have been pre- viously excited through the proper nerves of motion. They establish a communication, as it were, in a circle, between the muscles and the sensorium, whose office it is to regulate the extent of the action of the muscles ; and they carry to the mind that knowledge of the condition of the muscles, without which their actions could neither be controlled nor adjusted, nor be under the guidance of volition. Let us observe what takes place during vision, and we shall perceive how intimately this ' sense ' of the muscular actions is connected with the question before us. When we look at an object placed high above us, the first thing which we natu- rally do is to throw back the head, to turn the face towards the skies, to elevate the upper eyelids, and to raise the cornea of both eyes upwards. Now these actions are not performed without our knowledge. If we have to inspect an object which is placed on one side, we may be obliged to wheel round be- fore we can see it ; at all events it will be necessary to turn the eyeball in the socket towards that side. If we have to examine an object placed at our feet, there is first a corre- sponding motion of the eyeball and of the head, or it may be of the whole body, in order to be enabled to look downwards. in connexion with Vision. 251 These motions of the frame, accompanying vision, are familiar to all persons. We can even tell, at a distance, in what direc- tion a person is looking, by observing the position of his body ; and if we can see his eyes, we may tell whether he is looking at ourselves, or the particular spot that engages his attention. The boxer or the fencer knows full well how much the motion of the eye has to do with seeing ; for it is by watching keenly the eye of his adversary, that he learns the exact place where the blow is to be struck, and can parry it. There is invariably associated, therefore, with seeing, a particular position of the organ of vision ; and if it be allowed that we possess the con- sciousness of this position of our organ, it must, I think, be concluded that this is the source of our ideas of direction. We contrast the position of the eye necessary for seeing one object with distinctness, with that which is required for seeing another. Certain standards of comparison are arbitrarily fixed upon, and it is by referring to these that we assert that an object is placed high or low, to one side or to the other. If we turn our eyes upwards from the ground, we say that the object is high ; if we direct it downwards, we say that it is low : and, in the same manner, we say that it is placed to the right or to the left side, according to the direction in which the eyeball is revolved when looking upon it. Thus it would appear that the motions of the body and of the eyeball together, constitute an important part in our percep- tion through the organ of vision. The consciousness of the action of the muscles accompanies the sensation which the retina bestows ; and it is the almost simultaneous reception of these two different kinds of sensation, added to the effects of early habit in associating them, that gives rise to the common feeling of their both being obtained from the exercise of the same sense. If we now apply this view of the manner in which the 'direc- tion' of objects is discovered, to the problem of * erect vision from an inverted image,' it will afford an easy explanation of it. I ought first to state, that there are no reasonable grounds for the notion, that an inverted image upon the retina must neces- sarily be attended with an impression of the object, which is looked at, being also inverted. The opinion has been held, 252 Mr. Shaw on the * Sense* of Muscular Action that originally, as during infancy, all objects are seen inverted, and that some process is required to correct this false impres- sion. But there appears to be no reason for entertaining such a conception. The connexion established between the image upon the retina and the mind which receives the sensation, is altogether so incomprehensible, that no distinction can be sup- posed to depend upon the image being either inverted or erect. There would be an absurdity in speaking of the image being inverted in reference to the mind, which is incorporeal, as we speak of it being inverted in reference to the eye or the external object ; and the process of sensation would not be a whit more intelligible, if the image were placed erect instead of being in- verted. It is more just to believe that the image, of itself, can give no impression whatever of the position of the object, but only those sensations which proceed from light, as the varieties of colour, brightness, shadow, outline, &c. The question is simply, How does the idea of direction first enter the mind ? — how do we ascertain that the base of an object is placed towards the ground, and its top towards the skies ? And this question may be considered as one altogether independent of the position of the image at the bottom of the eye. If we proceed upon the principle which has been stated above, the answer to this question must be — that we judge of the direction of the various parts of a body by ascertaining in what position we must place the eye, in order to see it dis- tinctly. When a tree, for example, is presented to our view, we direct the eyes downwards to observe its trunk rooted in the earth — we turn them upwards to see its uppermost branch ; and we turn them to each side to see the right and left sides of the tree : and it is by referring to these motions that we conclude that one part is above, or another is below. In all of these motions, however rapidly performed, a distinct sensation - accompanies the change ; and this is communicated to the mind as surely as is the impression upon the retina itself. If we sought for an analogy, we might find it in the hand ; for the law is ' exactly the same by which we take an object, and touching it -upon one extremity, we say that is its top ; and touching it upon : another, we say that is its bottom. We observe what is the * extent of motion of the arm in reaching from its highest extre- in connexion with Vision. 253 mity to its lowest ; and it is by this sensation, combined with the sensation communicated to the skin, that we determine the position of the object through the sense of touch. The most remarkable circumstance connected with this sub- ject is the minuteness and the precision with which the eye can observe the differences of place or direction in objects. This can only be explained by referring to the extraordinary fine- ness of the sensibility to the different degrees of light which be- longs to the spot of the retina situated in the axis of vision, and to the susceptibility of the muscles to perceive the smallest variations in the position of this spot while engaged in directing it towards objects. Things which, from their minuteness, almost elude our naked sight, can be divided into upper, lower, and lateral parts. The conclusions to be derived from this mode of explaining the nature of a perception through the organ of vision, are both curious and highly interesting. We learn that the ideas of objects, which we are in the habit of saying are acquired through the eye, are never the productions of that one organ ; but, as if it were for the purpose of certifying the reality of the things around us, and placing this reality beyond the doubts of philosophers, who may have been bold enough to question it, two distinct senses are called into operation. Thus before we obtain the assurance of the simple fact, that the tree before us has its trunk fixed in the ground, and its leaves in the air, the optic nerve must, in the first place, convey the representation of the tree, that is, its colours, shadows, and outlines, by which it is distinguished from other objects ; while, in the second place, the muscles must cause the eye to traverse all its boundaries, taking points, and marking distances, so as to estimate its height and breadth, figure and position. There are thus not only two senses, but a process of compa- rison, calculation, and judgment, which implies an operation of the mental powers, combined in making this simple perception of a tree complete. Without going further into this subject, I may be allowed to remark, that to the medical man it is of much importance to study the mode of operation of the organs of the senses, and particularly of that which has been under our consideration. The questions connected with squinting and disordered actions ,of the muscles of the eye, which are still so little understood, 254 Mr. Shaw on the < Sense ' of Muscular Action, #c. may derive assistance from attending to the intimate connexion which has been shown to exist between the retina and the muscles. When it is observed that the state of activity of the optic nerve draws along with it an activity of the muscles, and that both these parts are equally engaged in the simplest act of percep- tion, it is to be expected that the derangement of the one will materially affect the other. But the nature of these actions of the muscles of the eye cannot be properly understood, unless we attend also to the involuntary motions of the eyeball ; by which the eye, at the instant that the optic nerve falls into a state of repose, becomes subject to the operation of a distinct class of muscles. The consideration of these subjects, together with the study of the complicated process by which an act of perception is com- pleted, may perhaps throw some light upon the questions of disordered vision, hallucinations, and some of the delusions of the mind arising from false perceptions of the objects of sight. For the principles on which these views of the nature of vision are founded, I beg to refer my reader to the ' Essay on Single Vision,' by Dr. Wells ; where the first indications will be found of the knowledge of a ' muscular sense ;' to the posthu- mous writings of Dr. Brown ; but more particularly to the papers published by Sir Charles Bell, on the nerves which supply muscles, and on the nerves and muscles of the orbit. ON THE INDURATION OF CHALK AND CHALK EARTH UNDER WATER, AND THE APPLICATION OF THIS PRO- PERTY IN HYDRAULIC ARCHITECTURE. By J. PENNISTON. [In a letter to Dr. Fowler, of Salisbury.] Dear Sir, IN compliance with your wish, I will relate to you, in writing the practical observations I have been enabled to make of the properties which chalky substances have of consolidating and hardening in the water. The first circumstance of any consequence that occurred to me in this way was previous to the repair of Harnham Bridge, which it was my professional duty to direct as Surveyor for the county of Wilts. I was then induced, on the recommendation of the foreman Mr. Penniston on the Induration of Chalk. 255 of the masons, to make the bays of chalk, or rather of chalky earth, which forms the banks adjoining the turnpike-road at the bottom of Harnham Hill. The stream, as you are aware, at the upper side of this bridge, runs extremely rapid, and I confess I had my doubts whether this material would consolidate in so narrow a width (not exceeding 2^- feet), and confined only between two hur- dles (such as are commonly used for penning sheep), suffi- ciently to resist the force of the river. In the progress of forming this bay, a considerable portion of the finer particles of the earth washed away with the cur- rent, but sufficient remained to answer every purpose intended. It was formed by men treading in the earth ; and on the evening of the day on which it was made, the whole substance was like a bog, or quagmire, where pressure on any part ope- rated on the whole bulk ; but on the following morning it was a perfect wall : it continued for many weeks impervious to the pressure of the stream, and when it was necessary to remove it, it presented so obstinate a resistance, that several pickaxes were broken in attempting to do so ; nor was it until the fol- lowing summer, when the water was lower, that it was fully cleared away, and then with the same labour and loss of iron as before. The next proof I had of its utility, was at Burford Bridge (a village just above Amesbury, Wilts). Here the pier of a cast-iron bridge was literally underwashed, and in great part destroyed, by the floods of 1823-4, and the bed of the river so ploughed up, as to be in holes of from five to ten feet deep. These, after restoring the piers, and repairing the bridge, I filled up by driving piles, and ramming in between these piles large rubble chalk, clay, and flints ; but in spite of the care I took in the execution of that plan, the floods of the succeeding winter cleared it completely out. A great portion of the lumps of chalk were rolled some scores of yards down the stream. The piles and clay vanished altogether. The specimens I had had of the chalk earth, induced me to fill in these holes with the same kind of materials ; and I employed some horses and carts to bring it from a chalk-pit at some little distance, selecting such as had been pulverized by wet and frost, and carefully discarding the larger lumps. 256 Mr. Pennlston on the Induration of Chalk. The immediate effect of this operation was more surprising than the former : as the carts were backed into the river, and their contents tipped into the stream, the consolidation was almost immediate, for as the carts successively came with their loads, the parts which had been previously filled in were ca- pable of bearing the wheels, with their loads on them. The whole wash was filled in at a comparatively slight expense, and remains perfect to this hour. From these proofs it has occurred to me, that if the same material were used to strengthen the bed of the Thames in the line of the Tunnel yet to be excavated, it might be attended with the happiest results. All that would be required, would be to bring in barges a sufficient quantity of chalk earth, and throw it into the river at low water : the current would do the remainder of the work ; nor have I a doubt, if it proved necessary to cut through a portion of this new-made bed in some future excavation, that it might be done with as much security as cutting through a solid rock of chalk. Having the honour of being acquainted with Mr, Timothy Bramah, I have mentioned to him the result of the experi- ments I have here described, and my opinion of their applica- bility, if the Tunnel should be renewed. The trial would not be a very expensive one, and I should be too happy if any suggestion of mine could, in the slightest degree, be beneficial in forwarding a work so nationally desirable to be completed. I am, dear Sir, &c. &c. July 16, 1831. J. PENNISTON. FURTHER OBSERVATIONS UPON SILICEOUS DEPOSITS FROM THE URINE. By ROBERT VENABLES, M. B., Physician to the Chelmsford Provident Society, &c. &c. HPHE existence of silex in the urine has been generally admitted, upon the authority of Berzelius, and he believes that it is accidentally derived from the water which we drink. Silex has been found, in three instances, intermixed with the composition of urinary calculi ; in two by Fourcroy and Siliceous Deposits from the Urine. 257 Vauquelin, and in one by Professor Wurzer. I believe I was the first, so far as I have been able to ascertain, publicly to notice the deposition of crystallized silex as gravel from the urine, the particulars of which have been already detailed in an earlier number of this Journal. At the period of sending the communication, and for some considerable time afterwards, I continued to enjoy frequent opportunities of witnessing the appearance of this deposit. It was not, however, a constant occurrence, but was occasionally interrupted for a time, and at various intervals reappeared. Upon one occasion, I trans- mitted the gravel, precisely as passed, to a gentleman * much .devoted to researches of this description, with a request that .he would acquaint me with his views upon the subject; and upon receiving his reply, I was much chagrined to learn that he had not been able to discover any siliceous matter in the specimen with which I had furnished him. As I placed the utmost reliance upon the correctness of this gentleman's con- ceptions, and the accuracy of his judgment, I almost regretted that I had committed my paper to the press, the more espe- cially as, upon several after occasions, the gravel exhibited all the sensible characters of the siliceous depositions previously observed; but upon chemical examination, it did not afford even a trace of silex. However, it was not long before I was gratified by the reappearance of the silex, a portion of which — the specimens being passed at different times — I sent to my friend, and found that he confirmed me in the fact of their siliceous nature. The only question with him then was their •urinary origin ; but upon this subject I fully satisfied myself by having the urine passed in my presence, so as to prevent the .possibility of practising any deception. Since the publication of that paper, Dr. Yelloly, of Norwich, discovered silex in small granules, * imbedded in the substance of an oxalate of lime calculus,' from the Norwich collection. The calculus weighed about five grains, and was taken from a boy about nine years old. The examination of this calculus, with the chemical proofs of the intermixture of siliceous gra- nules, is detailed at length in Dr. Yelloly's paper, published in 4he Philosophical Transactions. Dr. Yelloly, in consequence * Dr. Prout. 258 Dr. Venables on of my paper in this Journal, favoured me with a communica- tion upon this interesting subject, and, at his request, I had the honour of furnishing him with some specimens of silex passed by my patient. In comparing them with those discovered by himself, he observes that ' they bear some resemblance (though they are more minute and are of an amber tinge) to those which I have mentioned as coming under my own view *.' Very lately I had another opportunity of detecting very small siliceous particles in a crystallized form in some gravelly fragments passed by a patient of Mr. Green's, who happened to be visiting at this place. Having accidentally met with this gentleman, he was mentioning the circumstances of his case, particularly his frequently voiding quantities of gravelly matter. Having obtained a specimen recently passed, I found them to consist of lithic acid with volatile and fixed alkali and lime. The volatile alkali was evolved by heating with caustic potassa, and be- came sensible by the pungent smell. The presence of fixed alkali was proved by fusing a particle with a small quantity of very finely divided silex. Exposed on charcoal to the flame of the blow-pipe, the mass fused into a globule, the transparency of which was different in different instances. The gravel was of a pale cream colour, and seemed like so many fragments or scales of the outer covering of a small nucleus, having both a con- cave and convex surface. Among these I found a small nucleus of an irregularly rounded shape, and of about the bulk of a snipe shot. It was insoluble in muriatic acid, but soluble with effervescence in the nitric. Among the fragments which were of a cream -colour, I ob- served several which were of a much whiter appearance, and about the bulk of mustard-seed shot, irregular in shape. From their appearance I took them to be the mixed or fusible phos- phates, but upon urging a particle with the blow-pipe, I was surprised to find that it underwent little or no observable change, except that during the ignition it assumed a very bright or brilliant incandescence. After ignition it had a strongly alkaline reaction, and when moistened with distilled water it slaked and fell to powder like caustic lime, which an additional quantity of the water dissolved. On subjecting this solution * On the Tendency to Calwlua Disorders. Phil, Trans, 1830. Siliceous Deposits from the Urine. 259 to the action of a stream of carbonic acid gas, from a capillary jet, it became turbid, and a white powder subsided, soluble with effervescence in diluted hydrochloric acid, and which was again precipitated by oxalate of ammonia. Hence there can be no doubt that the base of this particle was lime. Another fragment of the same external characters being placed on a capsule, was dissolved with considerable efferves- cence by a few drops of diluted hydrochloric acid. The whole, however, was not entirely dissolved, but there remained at the bottom of the capsule three very minute crystals, which the acid could not dissolve, though aided by heat. The muriatic solution was very carefully withdrawn, and on being neutralized and heated with oxalate of ammonia, oxalate of lime precipi- tated. The three crystals were now carefully washed and removed to a platinum capsule, and boiled with concentrated nitric acid, but without undergoing the slightest perceptible change. The acid was driven off by evaporation, and the crys- tals submitted to the action of the blow-pipe on the platinum capsule, but without suffering any alteration. A little potassa and soda being added, on urging with the blow-pipe flame, solution with effervescence was effected, and the whole fused into a perfectly transparent colourless globule. The globule being pulverized and heated with distilled water, hydrochloric acid being added in excess, a gelatinous mass of very small bulk subsided after a considerable interval. When the jelly had consolidated into a closer and much less bulky deposit, which it did after a couple of days, the supernatant fluid was carefully withdrawn, and the precipitate being well washed with hot muriatic acid, was transferred to a small capsule, and the whole evaporated to dryness, leaving behind a white in- soluble powder, which resisted the most intense action of the blow-pipe. This analysis, therefore, fully proves that the little fragment, instead of being, as I at first imagined, composed of the fusible phosphates, consisted of carbonate of lime, with a very minute though still sensible proportion of crystallized silex. Hence then it would appear that silex, though rarely, does occa- sionally appear in a crystallized form in the urine. Berzelius, indeed, estimates its quantity at .03 in the thousand parts, but 260 Dr. Venables on upon this subject I may observe that it is not always present in the urine of the human subject, nor is its appearance constant even when occasionally discoverable. I have repeatedly analysed the urine of the same individual, and have at times readily found distinct and satisfactory traces of silex ; while at others, after the most careful and minute investigation, I have been unable to discover the slightest indication of the presence of this substance. Being anxious to ascertain whether the silex was confined to this one fragment, or whether it existed in any proportion in the remainder, a quantity, amounting to a grain in weight*, was taken promiscuously from the mass, and being introduced into a test tube, and tolerably strong nitric acid added, heat was applied. It dissolved with effervescence. Distilled water was now added, and the tube, fixed in its stand, was placed under a glass jar and left at rest for forty- eight hours. There was no deposition whatever, which would have been the case if there had been any intermixture of silex. Ammonia being added till neutralization was nearly effected, oxalate of am- monia precipitated a considerable proportion of oxalate of lime. The presence of lithic acid was proved by exposing a portion to the action of caustic potassa in excess aided by heat, and then pouring off the clear solution. Acetic acid being added in excess, the precipitate was washed and collected on a capsule. The solution of this precipitate in nitric acid being evaporated to dryness, and then acted on by ammonia, proved the presence of lithic acid by the formation of purpurate of ammonia. The presence of carbonic acid in the white limy-looking particles was proved as follows : A very small test tube being filled with and inverted over mercury, a particle or two of the calcareous carbonate was introduced, and immediately rose to the top of the mercury. A small quantity of moderately di- luted hydrochloric acid was introduced, by means of another test tube, into that containing the carbonate. The diluted acid immediately rose to the surface of the mercury in the tube, and, acting on the carbonate, dissolved it with considerable effervescence ; the mercury at the same time descending in * The entire specimen with which I was furnished did not amount to two grains. Siliceous Deposits from the Urine. 261' the tube. Nitrogen gas was now introduced from a capillary pipe connected with a bladder of this gas into the tube, till the whole of the mercury and the muriatic solution were expelled. A longer tube being filled with and inverted over, mercury, about two drachms of lime-water was passed into it, and rose to the top of the quicksilver. The gas of the first tube was now passed into the second : the lime-water became muddy, and a diminution in volume succeeded from the absorption of the carbonic acid, the nitrogen remaining behind*. The re- cently formed carbonate being acted on by diluted hydrochloric acid, dissolved again with effervescence. The muriatic solu- tion being collected by a pipette, was precipitated by oxalate of ammonia in the usual way, — thus proving the composition to be carbonic acid united to lime. The little nucleus which, it has been noticed, was placed in a capsule and subjected to the action of nitric acid, next at- tracted my attention. The capsule had been left at rest for several days under a glass, and on examining it there was found a very minute residue of an indistinctly crystalline ap- pearance, but of high refractive density. The capsule was heated and the acid boiled, but the boiling effected no solu- tion. After subsidence, the acid was removed as carefully as possible ; it was then evaporated till the whole of the acid was driven off. The insoluble residue was now ignited by the flame of the lamp enlivened by the blow-pipe directed upon the mass in the capsule: it effectually resisted the heat, under- going no alteration whatever ; but, on adding a little soda, it melted with effervescence into a transparent convex button, flattened at the bottom by the shape of the capsule, thus prov- ing the siliceous character of the residue. Hence, then, it appears that, in this specimen of gravel, there were distinct traces of silex in two separate fragments. In the one, the silex was in a crystallized form and in- termixed with carbonate of lime: in the other, it was in an amorphous or pulverulent form, and mixed with lithic acid combined with ah alkaline and earthy basef . If I had • This was the most easy and ready process with so minute a quantity. f From the nitric solution carbonate of potass precipitated carbonate of lime in large proportion, soluble with effervescence in hydrochloric acid, and reprecipitable by oxalate of ammonia. 262 Dr. Venables on detected the silex in the carbonate of lime fragment only, from the minute portion, and no silex being discoverable in the general mass, I might have been tempted to suppose that the carbonate of lime was an accidental impurity, not legiti- mately referable to a urinary source, although it is not easy to credit or even suspect that the whole of the intermixed frag- ments of carbonate of lime were mere accidental contami- nations. But the detection of silex imbedded in lithic salts leaves no doubt of its urinary connexion ; and this circumstance renders the urinary origin of the crystallized specimen no longer equi« vocal. What the peculiar circumstances are which determine the mode of appearance, it is difficult, nay impossible, in the present state of our knowledge, to determine. The more the earthy diathesis seems to prevail, the greater the tendency in the silex to separate in the crystallized form ; and, indeed, so far as the few facts ascertained upon this subject will warrant an inference, the deposition of silex seems connected with an earthy diathesis. Fourcroy and Vauquelin found the silex in phosphate of lime ; Dr. Yelloly found it in oxalate of lime ; Professor Wurzer found it in a calculus consisting principally of lithic acid with a small proportion of phosphate of lime. Wurzer's calculus yielded 1 per cent, on analysis. Its com- position was as follows : — Phosphate of lime 17 .33 Lithic acid 75 .34 Animal matter 6 .33 Silex 1 .00 100.00 Alemani gives the chemical composition of a urinary cal- culus, containing not only silica in large proportion, but also phosphate of iron. It was as under :- — Magnesia 51.00 Silica 20.00 Phosphate of iron 21 .84 Carbonate of magnesia 4 . 00 Loss 3.16 100.00 However, the composition of this concretion is so extra- Siliceous Deposits from the Urine. 263 ordinary that, allowing the analysis — of which, however, the details are not given — to be correct, doubts may be fairly en- tertained of its urinary origin. From its composition, it is more legitimately referable to the class of mineral productions. In the case noticed, in an earlier number of this Journal, as occurring to me, and in another, with the circumstances of which I was not personally so well acquainted, the urine showed a great tendency to alkalescence. They were both women ; and one of them, Newton, died lately, after having been much afflicted ; the other has left this neighbourhood, and I have not heard of her for some considerable time. I regret much that I had not any opportunity of examining the urine in the present case, the gentleman having quitted this neighbourhood the day following that on which I saw him. I understood him to say that he passed water with great diffi- culty and pain, and that much exertion brought on a discharge of blood. 1 understood also that, on sounding, no calculus could be discovered ; and, indeed, the shape and size of the fragments tend to prove that, if formed, it must be of very small size. I have generally observed that the secretion of much earthy matter is connected with an alkaline diathesis, and, indeed, soon induces disease of the bladder. The circumstances which give rise to the appearance of silex in the urine are enveloped in the utmost obscurity. I believe it has not been observed to separate from the urine (after being passed) in a crystallized form spontaneously, nor can it be effected by art. I certainly once observed a deposi- tion of something like crystallized silex on the sides of a tall jar, in which the urine of one of the patients, whose case I have described at length in an earlier number of this Journal, had been suffered to stand for several days; but I must observe upon this subject that, owing to an accident, I had not an op- portunity of verifying my supposition by a chemical examina- tion. The quantity observed in the present case is so minute, that possibly it may be looked upon rather as an accidental in- gredient. To this, however, it may be objected, that its appear- ance in the crystallized form is not exactly compatible with such a view. That pulverulent, or finely comminuted silex, might be introduced with drink into the stomach, and pass (in the VOL. II. Nov. 1831. T 264 Observations upon Siliceous Deposits, fyc. gelatinous state), as fluids frequently do, to the kidneys by some less circuitous route than the circulation, it is possible to con- ceive ; but that it could pass in a crystallized state, either by this shorter route, or through the more circuitous one of the circulation, I think will not readily be admitted. There is no other way, then, of accounting for the appearance of this sin- gular deposit, but its secretion by the kidney, and its separa- tion, as other morbid concretions. Nor is there more difficulty in conceiving the kidney capable, under certain circumstances, of such an elimination, than an operation of which there can be no question— the formation of the CYSTIC OXIDE. NOTES UPON VEGETABLE TISSUE. By JOHN LINDLEY, Esq., F.R.S., &c. No. 1. — Cellular Tissue. T> OTANISTS generally recognize three principal elementary forms of tissue, of which, under a variety of modifications, all the parts of plants are constituted ; these forms are the cel- lular, the fibrous, and the vascular. As far as regards tissue, in a state of perfect organization, the limits of these divisions are sufficiently exact, and the latter may be understood as elemen- tary forms ; but, if we consider tissue with reference to its own constituent parts, we shall find that these three principal forms are constructed of something still more elementary: viz., mem- brane and fibre ; and that, under the head of cellular tissue, are really comprehended certain modifications, composed of no- thing but the latter elementary matter. Cellular tissue is well known to be the basis of vegetation, to be that form which is indispensable to the existence of a vegetable being, and, therefore, to be in all cases present; while the two other forms are present or absent in plants ac- cording to their species. In its most common state, it consists of numerous minute, imperforate, transparent vesicles, pressing the one against the other, and by this pressure acquiring various figures, such as the dodecaedral, the prismatic, the columnar, the cubical, &c. ; its sides are destitute of all markings, except Mr. Lindley on Vegetable Tissue. 265 such as may arise from the adhesion of grains of grumous matter to them, and evidently consist of nothing but a very delicate membrane. This, which is the general character of cellular tissue, is not unfrequently considered its absolute dis- tinction ; it appears, however, from recent observations, that it is subject to some very remarkable modifications. It is an old idea, that the membrane of all tissue is composed of interlaced fibres, but this opinion seems to have originated in theoretical views, and either not to have been founded upon ob- servation at all, or at least, not upon accurate observation ; the existence of such fibres, in any case, has been denied by Mirbel, Link, and others ; and it must be evident to any one, that, in cellular tissue generally, no trace of them is visible. Molden- hauer, however, noticed, so long since as 1779, that the cel- lules of the leaf of Sphagnum obtusifolium are marked by fibres twisted spirally; but this met with scarcely any attention. Link states, that his supposed fibres are nothing but the lines where small cells, contained in a larger one, unite together ; and other botanists pass by the subject without remark. It is, nevertheless, certain, that the observation of Moldenhauer was perfectly correct, and that the cellular tissue of Sphagnum con- sists of a membrane, within which a fibre is twisted in an irre- gularly spiral manner ; it also appears that this kind of struc- ture is far from uncommon. In November, 1827, I described the tissue of the testa of Maurandya Barclaiana (See Botanical Register, t. 1108) as consisting of cellules, formed of spiral threads crossing each other, interlaced from the base to the apex, and connected by a membrane ; this was named, at the time, reticulated cellular tissue, and an approach to it has since been remarked in the seed-coat of several Bignoniacese. In 1828, Dr. Mohl stated, that in the pith of Rubus odoratus, he had seen cellules, the walls of which were marked with delicate fibres having a reticulated appearance ; and that other cases existed, in which the fibres (instead of being reticulated) formed curved lines, parallel with each other (see his Memoir uber die poren des Pflanzen-zellyewebes). In August of the same year, I was so fortunate as to discover upon the testa of Collomia linearis, the existence of incredible numbers of spiral fibres, * lying coiled up spire within spire, and confined by a dry T2 266 Mr. Lindley on Vegetable Tissue. mucus, so as to be unable to manifest themselves ; but the instant water is applied, the mucus dissolves, and ceases to counteract the elasticity of the spiral vessels, (spires,) which then dart forward at right angles with the testa, each carrying with it a sheath of mucus, in which it for a long time remains enveloped, as if in a membranous case.' (See Botanical Re- gister, t. 1166.) I, however, fell into the error of considering them spiral vessels ; they are no doubt analogous to those forms of cellular tissue, in which a fibre only is developed, and are probably of the same nature as what Mr. Brown de- scribed, in 1814, as spiral vessels in the testa of Casuarina. These cases had clearly demonstrated the coexistence of both membrane and fibre, in the cellular tissue, and also that if the latter is usually found composed of membrane only, without fibre, it is occasionally composed of fibre without membrane. Besides these instances, Meyen, about this time, described fibrous cellules in anthers. It was not, however, till last year, that the existence of fibrous cellular tissue was proved to be so extremely common in flowering plants, that scarcely a species can be named in which it does not exist abundantly. It appears from the descriptions of Dr. I. E. Purkinje, (de cellulis antherarum fibrosis, &c.) who, however, does not appear to have been aware of the abovementioned observations, that in anthers, the inner lining of the valves consists exclusively, either of membranous cellules, the sides of which are marked by fibres, arranged either spirally or otherwise, or of fibres only, arising from the cuticle, projecting into the cavity of the anther, and unconnected by any membrane. This statement is illustrated by good figures of nearly three hundred instances, the accuracy of some of which I have so verified, that I feel confidence in that of the remainder. It seems probable that this structure, now that attention has been called to it, will be found far from uncommon in the cellular tissue of other parts of plants. I have observed it in the leaves of Brassavola tuberculata in the same state (a very imperfect one) as Dr. Mohl found it, and as I have myself seen it in Rubus odoratus : and it exists in a state of beautiful perfection in the leaves of Oncidium altissimum, where some of the cellules, much larger than the rest, are evidently Mr. Lindley on Vegetable Tissue. 267 formed by the development of a spiral fibre within a membrane. This being the case, there seems to be no doubt that the basis of cellular tissue is both membrane and fibre, and that the character hitherto assigned to it will require to be much modified in consequence. It may possibly become more diffi- cult to define the exact difference between cellular and vascu- lar tissue : but it will be much less difficult to understand the origin of the latter; and a knowledge of the real character of the former will explain the presence of such tissue as the Elateres of Jungermannia among cellular plants, without the necessity of supposing the existence in them of partial ten- dency to vascularity. (To be continued,} ON HARRIOT'S PAPERS. By S. P. RIGAUD, M.A. F.R.S. Savil. Prof, of Astronomy. [To the Editors of the Journal of the Royal Institution.] Gentlemen, Oxford, Sept. 1, 1831. A LLOW me to request that you would correct a mistate- ment which appears in the third Number of your Journal. Neither you, nor the author of it, could have been aware of the injustice of the accusation which it conveys, or I am confident that I should not have occasion to make this appeal to you. In a very curious dissertation on the first invention of teles- copes, Dr. Mohl takes occasion to say (page 495 of your first volume), * it is to be lamented that Harriot's papers and manu- scripts are at present buried in one of the libraries of the University of Oxford.' Now the truth is, that these papers and manuscripts are not, and, what is more, never were in any of our libraries. The story is old ; but as it appears that an erroneous impression respecting it still exists, it may yet be right to lay the real state of the case before the public. Harriot lived under the immediate patronage of Henry Earl of Northumberland, from whose daughter the present Earl of Egremont is descended, and from whom he inherited these 268 Mr. Rigaud on Harriot's Papers. papers. Zacb, when a young man, was in England with Count de Bruhl, who married the dowager Lady Egremont, and by this means he got access to the manuscripts at Pet- worth. He found Harriot's papers there in 1784, and early in 1786 he made a proposal to the University of Oxford to prepare a portion of them for the press, if they would under- take the expense of the publication. This was immediately acceded to, and in April 1786, he wrote a long Latin letter on what he intended that his first volume should contain. A life of Harriot, written in imitation of Gassendi's lives of Purba- chius, Regiomontanus, Copernicus, and Tycho Brahe, was to make up the first part, and it was to be followed by some original observations of the comets of 1607 and 1618. Upon the receipt of this communication, an order was made, at the .next meeting of the delegates of the press, for the printing to be proceeded in as soon as the editor was ready. Nothing, however, was done by him ; and after a lapse of eight years, he sent, in May 1794, by Bishop Cleaver, then Principal of Brasen- nose, not the work which he had promised, completed and ready for the press, but a certain number of the original manuscripts, without any of the apparatus which he was to have drawn up for them. In the intermediate time he had printed an ac- count of the papers in the Astronomical Ephemeris of the Royal Society of Berlin for 1788, which was translated into English, and circulated in this country. It was probably drawn up from loose memoranda : it is easy to understand that the pleasure of his discovery might have led him to over- rate what he had found ; but such a feeling will not account for the very erroneous statement of facts which he gave, and which may be attributed to an imperfect recollection of the particulars which he intended to describe. He likewise printed, in Supplement I. to Bode's Jahrbuch (1793), an account of the observations of the comets of 1607 and 1618. This was probably what he had intended for a part of his first volume ; and if so, it not only marks the time when he had abandoned his original intention, but gives us such a specimen of his work as diminishes the regret which might be felt for his not having gone on with it. To return, however, to 1794. The delegates of the press Mr. Rigaud on Harriot's Papers. 269 had every wish to promote the publication ; but things were now materially altered. They had undertaken to enable Zach to bring out a work, which he professed to be preparing for publication ; but he had not only gone back from his engage- ment, but had thrown them into a situation, in which he would have made them responsible for working up the materials which he had thought proper to select for them. This last circumstance corroborates a correction, which must be made with respect to the manner in which the business was managed. The general idea is simply that Zach, having found these papers, the Earl of Egremont, in consequence, sent them to Oxford for publication ; in that case, however, he would most probably have sent the whole, that a judgment might be formed of the connexion and value of the several parts ; but the truth is that Zach, from the beginning, merely endeavoured to make the most of his discovery for himself. He applied to the uni- versity, in the first instance, to print his work, because, as he expressed himself in his Latin letter of proposals, ' quo tern- pore et quo auxilio in lucem proferretur, nulla erat post tot tantosve conatus spes relicta, nullum relictum consilium.' When he had given up this object he printed the observations of the comets (possibly the only part which really called for publication), and then made his retreat, so as to turn the eyes of the world from himself to the university. Nothing, of course, could have been done with the papers without hi$ having previously obtained the permission of the nobleman to whom they belonged ; but Zach appears to have made himself the prime agent in the whole business, so that no direct inter- course took place between the university and the Earl of Egre- mont, till after the undertaking had been finally given up. I suspect that the delegates themselves were not apprised of their only having a portion of the papers ; at least I can recollect no allusion to it from those of former days with whom I have conversed on the subject, and the fact has certainly not been generally known ; but, however this may have been, it had become necessary for those who acted on the part of the university, to take the precaution of inquiring further, and ascertaining the nature and character of what had been put into their hands. The late Dr. Robertson was, therefore, re- 270 Mr. Rigaud on Harriot's Papers. quested to make a report on those papers which were connected with abstract mathematics ; and the astronomical part was put, for the same purpose, into the hands of the late Mr. Powell, of Balliol. This took place in July 1794. I mention the specific dates to show that I am not writing from vague tra- ditionary accounts, but from precise documents which are still in existence. In the following October, Dr. Robertson reported that what had been submitted to him was not calculated for publication ; and here the matter rested for some time. Mr. Powell had been prevented from attending to the business, and the delegates, therefore, at length referred his part of the papers also to Dr. Robertson. His opinion, which he gave with the reasons for it in 1798, was in this case likewise against the publication ; and in the following year the whole was restored to the Earl of Egremont. In spite of the fear of being tedious, I have thought it right to enter into all these particulars, because they prove that no blame, in the slightest degree, attaches to the university. None, indeed, could have been brought forward if these facts had been generally understood. But unfortunately they were not. Dr. Hutton inserted Zach's account of the papers in his Dic- tionary (Art. Harriot), and, without sufficient inquiry, added, 6 It is with pleasure I can announce that they (Harriot's papers) are in a fair train to be published j they have been presented to the University of Oxford, on condition of their printing them ; with a view to which they have been lately put into the hands of an ingenious member of that learned body to arrange and prepare them for the press.' The first edition of the Dictionary was printed in 1796, and some allowance might then be made for misapprehension ; but Dr. Hutton was the old personal friend of Dr. Robertson, and might have ob- tained any information that he desired from him on the sub- ject ; some correction ought, therefore, to have been introduced in the second edition of 1815. Zach's erroneous statement, however, was reprinted in that and many other books both here and abroad : in some cases the substance of Dr. Hutton's inaccurate addition was annexed, and the story was repeated till the whole of it was received as authentic. In this manner obloquy has been brought upon Oxford, because Zach had Mr. Rigaud on Harriots Papers. 271 too eagerly raised expectations which did not admit of being fulfilled. By the kindness of the Earl of Egremont I have recently been entrusted with these very papers ; some of them are very curious, but, as far as I have had time to examine their contents, I have found very little which it would be useful to publish. I can, however, refer you in this respect to better authority than my own. In 1822, Dr. Robertson communicated his reports on them to Dr. Brewster, and they were printed in the Edinburgh Philosophical Journal (vol. vi. p. 314). They refer, of course, only to those papers which were sent to Oxford ; of the remainder any one in London may form his own opinion, as a considerable quantity of them was given^ I believe, in 1810, by Lord Egremont, to the British Museum. There were, before that time, some other MSS. of Harriot's in the same place (No. 6001-2, and 6083 of the Harleian collection) ; An- tony Wood (Ath. Ox. vol. i. p. 391, 1st. ed.) speaks of a MS. of his, entitled e Ephemiris Chyrometrica,' which he says was in the library of Sion College, but no mention of it is to be found in Reading's Catalogue ; and, although Harriot was an Oxford man, I am not at present aware of our having any papers of his in any of our libraries. S. P. RIGAUD. ON THE MAGNETIC INFLUENCE EXHIBITED DURING AN AURORA BOREALIS. By S. H. CHRISTIE, Esq. M.A. F.R.S. &c. TN an account which I gave of some observations on the aurora borealis of the 7th of January last, I stated that it was my intention to adjust a magnetic needle for the purpose of observing the effects produced on it during an aurora, should there be any recurrence of the phenomenon. This I immedi- ately did, but was not fortunate enough to be able to make any observations until the aurora of the 19th of April. In order that the nature of the action on the needle may be clearly understood, it is necessary that I should point out the 272 Mr. Christie on the Aurora Borealis. manner in which the needle was adjusted, and how the cha- racter of the forces acting upon it may be inferred from the changes observed in its direction. I suspended a light needle, six inches in length, by a fine brass wire ^i^th of an inch in diameter, and twenty-three inches long, within a compass-box, having a ring graduated to thirds of a degree. In the direction of the axis of the needle, and at equal distances from its centre, were placed two twelve-inch-bar magnets, the south-pole of each being towards the south. These were made gradually to approach the needle until their repulsive force on its poles was some- what greater than the terrestrial directive force. When this was the case, there were three positions of the needle in which the forces acting upon it were in equilibrio, viz., when its south pole or marked end pointed south — when it pointed some- where between north and west — and likewise when it pointed somewhere between north and east. At the time when the observations which I am about to give were made these posi- tions were nearly south, N. 37 °W., N. 37° E., and the observa- tions were made on the deviations of the needle when it pointed between north and west. Being engaged on the 19th of April in preparing for a journey, I should not have observed the needle on that even- ing, nor have been aware of the occurrence of the aurora, had not Mr. Faraday called to inform me of it. A few minutes before ten o'clock, when I first saw it, there was a steady stream of yellowish light in the west, 12° or 14° in breadth near the horizon, and clearly perceptible to the height of 40°, although the moon was quite free from cloud : to the north there were streamers shooting upwards, and masses of white light sometimes forming irregular arches. Shortly afterwards there arose from the horizon a very strong stream of light, nearly in the magnetic meridian, 3° or 4° in breadth, very distinct to the height of 50°, and gradually lost towards the zenith. This stream continued steady for about four minutes, when it gradually disappeared. Immediately after this I ob- served the needle, adjusted as I have described. At 10 h. P. M., I found the needle vibrating between N. 43° 40' W. and N. 42° 407 W. The vibrations, continuing Mr. Christie on the Aurora Borealis. 273 about 1° in extent, gradually increased towards the west, and decreased towards the north, until the needle reached IS. 55° 30' W., at which time there was a strong stream of light from the magnetic north. When this had disappeared, the needle returned gradually, and very steadily, towards north ; at length, reaching N. 34° W. : at 10 h. 15 m , the direction of the needle was N. 34° 40' W. Soon after this, I again ex- amined the needle, and then made the following observations : At 10 h. 30 m. the needle vibrated between N. 40° W. and N. 39° W. 10 33 the direction of the needle was . N. 36 30' W. 10 35 . . . . . N.35°W. 10 37 . . . . . . N.34 W. 10 37£ . . . . N. 33°30'W. 10 39 the needle vibrated between N. 34° 20' W. and N. 33° 40' W. 10 42 . . . . N. 36° W. and N. 35° W. 10 44 . . . . N.37 W. andN. 36 W. At this time there were no streamers, and the light was very faint in the north : barometer 29.94, thermometer 42°. I regret that circumstances would not allow of my continuing my observations throughout the night, which I was very desirous of doing. The next morning at 7 h. 20 m. the needle pointed N.40°W. The mean direction of the needle, when uninfluenced by the aurora, I consider to have been N. 37° W. As the needle assumed this position in consequence of the attractive force of the earth, acting on its south pole towards north, and of the repulsive force of the magnet, acting upon the same pole in the opposite direction, a deviation towards west would indicate a diminution in the terrestrial horizontal intensity, and a devi- ation towards north an increase in that intensity, the intensity of the magnets remaining the same. In a paper published in the Cambridge Philosophical Trans- actions for 1820, I first pointed out that the change in the direction of the horizontal needle, arising from extraneous action, would be best determined by referring the action to a needle freely suspended by its centre of gravity, and then refer- ring the direction of this to the horizontal plane; and stated, that in this manner we should be able to account for the changes which have taken place in the variation and dip of the 274 Mr. Christie on the Aurora Borealis. needle during a long series of years. Taking this view of the subject, Capt. Foster*, by a series of observations made at Port Bowen, in 1825, and published in the Philosophical Transactions for 1826, showed that the changes in the hori- zontal intensity of the needle might be referred to changes in the dip, the terrestrial intensity in the direction of the dip remaining constant, or nearly so. If then we consider that, during the time of the aurora, the absolute terrestrial intensity remained constant, the change which I observed in the direc- tion of the needle indicating a diminution in the horizontal intensity, it will follow that, during this aurora, the force developed was such as to cause an increase in the dip of the needle. The change that took place in the direction of the needle was so considerable (more than 21° in less than 15 minutes), that it required no nicety of observation to mark its progress. I have before mentioned, that I was so fortunate as to have Mr. Faraday with me at the time : the changes were so mani- fest, that he could observe them at a short distance from the instrument, at the same time that I was noting them more minutely with the assistance of a glass ; and he agreed with me, that the effects could not be more decisive of the influence exerted upon the needle during the aurora. It has been stated, that aurorse have occurred, during which no effect has been observed on the needle ; that this was re- markably the case in Capt. Foster's observations at Port Bowen ; and that these observations are ' a refutation of the supposed connexion between tremors of the needle and aurora borealis.' With regard to these observations we may remark, in the first place, that the needle was observed to be continually in a state of tremor, so that it must have been difficult to decide whether any effects were produced on the needle during the time of an aurora ; and, in the second, that, although magnetic effects may, in all cases, be simultaneous with the aurora, yet the direction of the horizontal needle may not invariably be * By the untimely death of this meritorious and estimable officer, science has lost an able, zealous, and indefatigable auxiliary — his friends one whom they must Jong continue to deplore. Mr. Christie on the Aurora Borealis. 275 affected. In order, however, to determine how far any effects were manifest in the direction of the needle, we will analyse the abstract of the observations made by Capt. Foster, at Port Bowen, in the months of January and February, 1825, during which" months it happens that, in each, the aurora was visible and invisible during the same number of nights as nearly as possible. Aurora visible. Aurora invisible. Date. 1825. Amount of Variation. January 12 . . 0°51' 15 . . 4 13 16 . . 2 25$ 17 . . 2 29 18 . . 2 56 20 . . 1 08 21 . . 1 17 22 . , . 1 20 24 . . . 1 03$ 26 . , . 2 00 27 . . . 1 55 28 . . 0 44 29 . . . 1 05 30 . . . 1 31$ Means February 6 11 12 13 14 15 16 19 20 21 22 23 24 25 1 47 1 27 3 53 2 46 2 25 5 00 4 25 1 41 1 55 1 41 1 53$ 2 10$ 1 46$ 0 19$ 0 45 Means . . . . 2 17.5 Means, Jan. and Feb. 2 02.7 Date. 1825. Amount of Variation. January 1 . 1°20$' 2 . 0 53 3 . 0 50 4 . 0 56$ 5 . 2 33 6 . 2 50 7 . 2 03 8 9 •^ no observations J recorded. 10 . . . 1 23 11 . . . 2 01$ 13 ... 1 00$ 14 ... 1 22 19 ... 1 56 23 . . . 1 16 25 ... 1 12$ 31 . . . 0 26 Means . ... 1 28 February 1 . . . 0 39 2 ... 0 52$ 3 . . . o 174 4 . . . 0 54 5 ... 1 14$ 7 . . . 0 46$ 8 ... 1 10$ 9 ... 0 51$ 10 . . . 0 47 17 . . . 2 46 18 ... 0 48 26 ... 1 24$ 27 ... 0 44 28 . . . 0 19$ Means • ... 0 5S/2 Means, Jan. and Feb. 1 13.7 276 Mr. Christie on the Aurora Borealis. From the means, it appears that the variation, during the days on which the aurora was visible, was greater than during those on which it was invisible ; in the month of February more than double, and on a mean of the two months nearly so. Taking individual observations, we have, in the month of January, when the aurora was visible, six days on which the variation exceeded the mean variation during the month, and eight days on which it was less ; when the aurora was not visible, five days on which it exceeded, and ten days on which it was less than the mean : and in the month of February, we have, when the aurora was visible, eleven ddys'ori which the variation exceeded the mean variation of the month, and only three on which it was less ; when it was not- visible only one day on which' it "exceeded, and thirteen on which* it was less than the mean. . Sp that, whatever may be the cause of the aurora, it is evident from these observations, that, during its occurrence at Port Bowen, the needle had in general a ten- dency to make wider excursions, although this tendency may, in many instances, have been counteracted. I am aware that results, directly the reverse of these, have been drawn from Captain Foster's observations. In the ' Edin- burgh Journal of Science,' vol. viii. p. 200, it is remarked that, * In the two months during which twenty-eight aurorse oc- curred, the mean monthly excursions of the needle on each side of its mean position was only 1° 37 J'; whereas during the two months when there were no aurorse, it was almost exactly double, viz., 3° 18' 41". If this difference, which' is far too great to be accidental, shall be confirmed by future observa- tion, it will prove that, in the arctic latitudes, and in those periods which abound with aurorse, the excursions of the mag- netic needle are diminished ; while, in our latitudes, the causes which produce auroras increase the excursions of the magnetic needle.' If we admit this, these observations prove that, during an aurora, magnetic forces are developed, a supposition which they have been considered to refute ; but I think .we cannot allow that the difference here noticed, in the extent of the variation, can be fairly connected with the aurora. The mean variation for the month of March, during which the aurora was only Mr. Christie on the Aurora Borealis. 277 Visible on three days, was 2° 14-25'; that for April 2° 52-44, and for May 3° 44-39', during which latter months the aurora was not seen on any occasion. So that there appears clearly to have been a progressive increase of the variation, quite inde- pendent of the aurora ; and to this progressive increase we ought to attribute the difference above noticed, more especially as, during the months in which the aurora was visible, the effect appears to have been to increase, instead of diminishing, the variation during an aurora. No one can set a higher value than I do on Captain Foster's observations, but I consider that conclusions have been drawn from them which they do not warrant, I have already stated, that although magnetic effects may in all cases be simultaneous with the aurora, yet the direction of the horizontal needle may not invariably be affected. This will be evident, if we consider the effects that may be produced on a magnetic needle, freely suspended by its centre of gravity, and refer the direction of this needle to the horizontal plane. If the forces developed are wholly in the vertical plane passing through this needle, it is evident that, although the inclination of the needle may be increased or diminished, yet no change will take place in its horizontal direction, and consequently no changes, in such case, would be observable in the horizontal needle. That this may frequently be the case is evident from the circumstance that the most brilliant beams of the aurora generally affect the magnetic north. I am not aware of the observations which may have been made on the direction of the horizontal needle, during the aurora of the 19th of April last, but as I have before stated, the greatest deviation of the needle which I observed, took place at the time when a strong stream of light issued from the magnetic north. Now, although the effect was here so sensible, owing to the peculiar adjust- ment of the needle, yet this effect may not have been observ- able on a horizontal needle, under the influence of terrestrial magnetism alone, however delicately that needle may have been suspended. If observations were made on a dipping needle, the effects of the forces developed in the plane of the meridian during an 278 Mr. Christie on the Aurora Borealis. aurora might become sensible ; but as this is at best a very imperfect instrument, and as these forces would probably in all cases be small, compared with the other forces giving direction to the needle, the effect produced would, very probably, be quite insensible. To obviate this, the directive force of the needle should be diminished, by placing magnets in the direc- tion of the axis of the dipping needle, with their poles opposite to the corresponding poles of the needle, the magnets being placed at such distances, that the force acting upon the needle in the direction of the dip should be extremely small. In observing, however, with a needle so adjusted, it would be necessary to be extremely cautious that the instrument and the magnets should be so securely fixed, that their relative positions could not alter during the observations, — as a very minute change would produce a very sensible deviation of the needle. In order to observe the effects produced by forces not acting in the meridian, it would be necessary also to adjust a horizontal needle in a similar manner. As the mechanical difficulties, occurring in such an adjust- ment of the dipping needle, are considerably greater than in that of a horizontal needle, I consider that it would be better to adjust two horizontal needles in this manner : — 1. A light needle being suspended by untwisted fibres of silk, a fine hair, or a very fine wire, two bar magnets are to be placed as I have described, and at such a distance that the marked end or south pole of the needle may still point to zero. Keeping the magnets in the meridian, and still at equal or nearly equal distances from the needle, they are to be made to approach it until the marked end deviates about 30° to the east, or west of north. If the needle be now led towards 180° or south, by means of a small piece of iron held on the outside of the compass box, it will remain at 180, provided the axes of the magnets are in the meridian : if it does not point to 180, the nearer ends of the magnets must be slightly moved east or west, without changing their distances, until it does. The magnets should now be firmly fixed in their positions by copper nails, and it would be advisable to cover them up with some bad conductor of heat, as a change in their temperature will Mr. Christie on the Aurora Borealis. 279 cause a change in their intensity, and should this be much diminished, the needle will quit its position at 180°, and resume that at zero. This needle being left in this position, its devia- tions will indicate corresponding changes in the direction of the magnetic meridian. 2. Another needle should be adjusted in a similar manner, but the magnets should be brought so near to it that the posi- tions in which the needle will rest become 180, N. 70° E. and N. 70° W. 5 and instead of being left with the marked end pointing to 180°, like the former, it should be led to the posi- tion between N. and E., or N. and W. (whichever happens to be most conveniently circumstanced for observation), at which it will remain. The changes in the direction of this needle will principally indicate changes in the terrestrial horizontal inten- sity, corresponding to changes in the dip. To those who are desirous of observing the magnetical effects produced during an aurora, and who have leisure to watch for the occurrence of this phenomenon, I would recommend such adjustments of two horizontal needles. During the time of an aurora, these needles should be carefully watched, the ob- server being very careful to remove from his person every article of steel or iron. Their directions should be noted at very short intervals ; if their motion be vibratory, the limits should be marked ; and the precise time when any change in the direction of their motion takes place should be carefully noted. Another observer should at the same time note any remarkable circumstance in the aurora, — as the appearance of columns or arches of light, their magnetic bearings and atti- tudes nearly, with the precise time of their occurrence. It is desirable, also, that the directions of the needles should be ob- served every day at intervals of an hour, throughout the twenty-four hours, particularly that of the needle pointing south, as this would be but little influenced by changes in the temperature of the magnets. By means of the latter observa- tions, not only the times of maximum east and west variation, and the relative extent of the variation each day would be deter- mined, but a comparison would be afforded between the ordi- nary diurnal excursions of the needle, and those during an aurora ; and they would besides enable us to determine with VOL. II. Nov. 1831. U 280 Mr. Christie on the Aurora Borealis. greater certainty, whether decided changes in the direction of the needle were simultaneous with the occurrence of distant aurorse. Royal Military Academy, 27th September, 1831. ON THE PHYSICAL CAUSE OF ENDOSMOSIS. By M. DUTROCHET. Read to the Academic des Sciences, 25th July, 1831*. TX7HEN two liquids, differing in capillary ascension, are separated by a thin and permeable partition, two cur- rents, flowing in opposite directions through this partition, are produced ; the strong current is that of the liquid which would rise highest, directing itself towards that which would rise the least, and the weak current is that of the liquid which would rise the least, directing itself towards that which would rise the most. The progressive augmentation of the volume of the liquid, which would rise the least, is the result of this double phenomenon. This augmentation is in proportion to the dif- ference, which exists between the force of the two opposite cur- jrents : it results from the excess of the strong current as compared with the weak current. This excess manifests itself by a simple dynamic effect, for the two opposite currents are in equilibrium, or in a state of compensation to the extent of their equal parts. The force resulting from this excess is that of the endosmosis. When I first discovered this phenomenon, I was led to con- sider it as the result of an electric impulsion ; and, in fact, the curious electric phenomenon discovered by M. Porret appears susceptible of being referred to endosmosis, may even be said not in any manner to differ from it. In this pheno- menon two portions of pure water are separated by a mem- brane and electrified, the one positively, and the other nega- tively, by the two poles of a voltaic pile. The water electrified * The Committee have succeeded, by means of their foreign correspondent, in establishing arrangements by which they may obtain original communications from abroad for publication in this Journal. The present paper by M« Dutrochet, on the important subject of endosmosis, is a paper of this kind, On the Physical Cause of Endosmosis. 281 positively, passes through the membrane to the water electrified negatively, gradually increasing the volume of the latter. The exact resemblance of this effect to that of endos- mosis produced by the difference in the density of the liquids, led me to consider the latter phenomenon as the result of an electric impulsion. The electricity appeared to me to be produced by the difference of density in the two liquids separated by the membrane. Further reflection has, however, induced me to abandon this idea: the body of water in contact with the positive pole disengages oxygen in a state of elasticity ; this water, therefore, becomes charged with hydrogen in a state of solution : the body of water in con- tact with the negative pole disengages hydrogen in a state of elasticity ; this water, therefore, becomes charged with oxygen in a state of solution. Thus we have, on one side, water charged with oxygen, and on the other, water charged with hydrogen, or, in other words, two liquids of unequal density. From that moment the phenomenon of endosmosis presents itself, and the water charged with oxygen being necessarily of greater density than that charged with Hydrogen, has its volume increased at the expense of the latter. Electricity here is not the immediate, but the remote cause of the pheno- menon : it is simply the cause of the difference in density of the two portions of water. This difference is undoubtedly very small, and, therefore, the phenomenon of endosmosis is manifested in a very slight degree. A very celebrated mathematician (M. Poisson) has sought to explain the phenomena of endosmosis on the principles of capillarity. The following is a summary of the theory which he has recently broached on the subject. The two hetero- geneous liquids being introduced into the same capillary canal by its two extremities, are at first both concave, but as soon as they unite, the one remains concave, while the other becomes convex, adapting itself to the concavity of its antagonist; then, by a mechanism founded on calculations made by the learned mathematician, the liquid which rises the highest, and which has remained concave, passes through the membrane, repelling the liquid opposed to it, and runs out : it thus augments the mass of this opposed liquid, with which it is mingled, U 2 282 Dutrochet on the Other physiologists, observing that the phenomenon of en- dosmosis does not take place when two liquids which are not susceptible of being mixed (such as oil and water) are placed in relation to each other, have supposed that the recip- rocal dissolution of the liquids played a principal part in this phenomenon, and that the gradual augmentation of the volume of the liquid of the greatest density, was the result of the greater facility of permeation possessed by the liquid of less density which was opposed to it. This theory is destroyed by positive facts ; thus, for example", sulphuric acid and water, which have the greatest tendency to a mutual dissolution, do not produce any endosmosis. The only mode of arriving at a certain theory upon the phe- nomenon in question, is to observe and appreciate its effects mathematically; this is what I have endeavoured to do by determining, in the first place, the laws regulating the force and velocity of endosmosis. I have ascertained that this force is in proportion to the difference in the density of the two liquids. Thus, for instance, if a solution of muriate of soda, the density* of which is 1*06, be brought into relation with water, the density of which is I, there will be a force of endosmosis which will vary according to the extent of surface of the membrane of the endosmometer. If, in the same instrument, there be put a solution of the same salt, the density of which is 1*12, this solution, being brought into relation with water, will produce a force of endosmosis, which will be the double of that produced, under the same cir- cumstances, by the solution having the density of 1.06. The two forces of endosmosis produced by these two saline solutions will, therefore, be to each other as the two excesses of density of these solutions above the density of the water, that is : : 00-6 : OT2, or as 1 : 2. I have endeavoured to ascertain whether there was any relation between this law of the endosmosis and that regulating capillary ascension, and for that purpose have examined the comparative forces of capillary ascension of pure water, and of the two saline solu- tions in question. I took a glass tube, the capillary attraction of which raised water to a height of 12 lines (one inch) in a temperature of 10° C. = 50° F., and found that the same Physical Cause of Endosmosis. 283 tube, under the same circumstances, raised the solution of muriate of soda, the density of which was T06, to a height of 9^ lines, and the solution, the density of which was 1*12, to a height of 6^ lines. Hence result the following calculations : — 1st. The capillary ascension of the water being 12. And that of the first solution 9.125 The excess of the capillary ascension of the water is 2.875 2nd. The capillary ascension of the water being 12. And that of the second solution 6.25 The excess of the capillary ascension of the water is 5.75 These two excesses are precisely in the proportion of 1 to 2, the same proportion which was found resulting from the expe- riments on the force of endosmosis produced by bringing the two saline solutions in relation with pure water. Thus we find the excess of the capillary ascension of pure water over that of the liquid opposed to it, which is denser, and conse- quently rises the least, determines the force of the endosmosis, which latter is, therefore, a special result of the capillary force. The only action of the difference in the density of the liquids is to produce difference of their capillary ascension, so that liquids of smaller density, which have a different capillary ascension, produce an endosmosis differing, and in proportion to the degree of their power of ascension : thus I have found that a solution of sulphate of soda, brought into rela- tion with pure water, produced an endosmosis double of that which a solution of muriate of soda of the same density pro- duced under the same circumstances. The cause of this is found in the measure of the capillary ascension of the two solutions. The capillary ascension of water in a glass tube being 12 lines, that of the solution of sulphate of soda, the density of which was 1-085, was 8 lines, while that of the solution of the muriate of soda, of the same density, was 10 lines. The excess of the capillary ascension of the water over that of the solution of sulphate of soda is 4, and over that of the muriate 2, or in the proportion of 2 to 1. Now this is precisely the proportion of that existing between the endos- mosis produced in the experiment made by placing each of these solutions, of equal density, but different capillary ascen^ 284 Dutrochet on the sion, in relation with the water. This phenomenon is, therefore, unquestionably produced by the excess of capillary ascension of one of the liquids separated by the partition of the endos- mometer. Hence endosmosis is the result of the opposition of two unequal capillary forces acting at the two extremities of the same capillary tube. These two forces impel the two opposite liquids towards each other in unequal quantities, so that one of them (that which has the smallest force of capillary ascen- sion) is gradually augmented in volume ; and it is this excess of capillary force which produces the endosmosis. Having de- monstrated that the endosmosing liquid is impelled towards the liquid with which it unites, in a quantity proportionate to the excess of its capillary ascension over that of the liquid towards which it is so impelled, it remains to be explained by what mechanism this phenomenon is produced. It appears certain that, under these circumstances, there are two opposite cur- rents, the one strong and the other weak : these two currents may be seen by putting muriatic acid into a glass endosmome- ter, and plunging it into a glass vessel filled with water. We shall then see the water rise, forming striae in the acid, and the descend, forming similar striae in the water. It cannot be supposed that these two opposite and unequal currents pass simultaneously through the same canals ; but it is possible that each capillary canal serves alternately to transmit the two opposing currents, and the following fact appears to prove it to be so. I put nitric acid into an endosmometer closed with a piece of bladder, and added to it some very small fragments of gold leaf. I then plunged the apparatus into water. The en- dosmosis was immediately produced, and I perceived that the water which it introduced into the acid raised rapidly some of the fragments of gold leaf, whilst others remained stationary against the membrane. The fragments of gold leaf, which had experienced an ascending impulse, fell again by their own weight upon the surface of the membrane : they remained motionless there for an instant, and were then again strongly impelled upwards : all the fragments of gold leaf presented these alternations of rapid ascension and fall, followed by a short repose on the membrane, but without being at all simul- Physical Cause of Endosmosis. 285 taneous. This fact proves evidently that the capillary canals, which transmit the water impelled towards the acid, or the acid impelled towards the water, do not contain a current con- stantly moving in the same direction. The fragments of gold- leaf, when they fall after their movement of ascent, are natu- rally directed towards the canals, which serve at the moment for the current descending from the acid towards the water ; they remain motionless on this spot until the canals upon the orifices of which they are placed change their descending into an ascending current, when they resume their upward motion under the influence of the ascending liquid. Without these alternations of the two opposing currents in the same capillary canal, it is not easy to conceive how the endosmosis can be equal to the excess of the capillary action of the opposite liquid. In order to explain the phenomenon, we should have to admit either that the two opposing currents existed simulta- neously in the same canal, which is impossible, or that the num- ber of the capillary canals of the membrane is equally divided between the two liquids, and consequently between the two cur- rents, and there appears no reason to suppose the existence of this equal division. But, as experience proves that the capillary canals do riot transmit the same liquid without discontinuance, it becomes necessary to admit that the same canal serves alter- nately for the two opposite currents : this is the only manner in which we can understand the exact relative proportion which exists between the quantity of liquid which is accumulated and the excess of the capillary action of that liquid over that of its antagonist. If, in opposition to what appears to be proved by experience, we assume that there is but one current through the membrane, and that the opposite current is but an optical de- ception, the result of the affinity of mixture of the two liquids, then the effect of endosmosis would be explained by the oppo- sition of two unequal forces of capillary impulsion ; part of the greater force would be employed to counterbalance the smaller force, the effect of which it would thus suspend or neutralise, and there would only remain the excess of the greater force of capillary impulsion over the smaller force to produce endosmosis. In this view of the case, it would not be necessary to admit that the same capillary canal serves 286 Dutrochet on the alternately to transmit two opposite currents : all the capillary canals of the partition of the endosmometer would be occupied by currents flowing in the same direction. Since the capillary action perfectly accounts for all the con- ditions of the phenomenon of the endosmosis, it is evident that the affinity of mixture of the liquids has no share in the production of this phenomenon ; it exists, it is true, as an accessory phenomenon, but has no dynamic effect. If the miscible quality of the liquids be necessary to the existence of the endosmosis, it by no means follows that their mixture acts as a dynamic cause of the effect produced. Endosmosis results from the opposed association of two unequal capillary actions. Now the capillary actions of oil and of water mu- tually destroy each other ; a tube, which has its interior sides rubbed over with oil, will not occasion the capillary ascension of water, so that there is not in this case any opposition of two unequal capillary actions ; there is but one, and therefore there is no endosmosis, The simple capillary action, which alone has been hitherto known, is a force which never impels liquids beyond the sphere of capillary action ; the double capillary action, which I have discovered, impels the two opposing liquids in opposite direc- tions across the capillary sphere of action, and tends to drive them out in unequal quantities on each side. All the organic animal or vegetable membranes, which may be used in closing endosmometers, are eminently adapted to produce endosmosis. Among the mineral substances, which may be used in very thin plates for the same purpose, baked clay is the best adapted to produce this phenomenon ; plates of carbonate of lime scarcely produce it at all ; I was, indeed, disposed to believe that the latter substance was totally incapable of' producing- it, but, on repeating my experiments, I succeeded in obtaining a very feeble, but still perceptible endosmosis with a plate of white marble of the thickness of one millimetre. All the liquids which are susceptible of a chemical combi- nation, with the permeable partition of an endosmometer, sus- pend the endosmosis, after having produced it for a longer or shorter period. Thus, when an acid, alkaline, or saline solu- tion is placed in an endosmometer, an endosmosis is at first Physical Cause of Endosmosis. 287 produced, but after some time this effect ceases, and the liquid raised above its level has a tendency to fall by filtration through the permeable partition. This occurs when the par- tition is modified by the acid, the alkali, or the salt. Alcohol produces the same effect, which results with extreme prompti- tude from the action of sulphuric and hydro-sulphuric acids, so much so, indeed, as to induce me to believe that these two acids are opposed to the endosmosis. The organic liquids, not having any chemical action on the membranes, or mineral partitions which may be employed to close the endosmometers, produce an endosmosis which would not be liable to any sus- pension if they always remained the same. But these liquids are decomposed and become acid or alkaline, and often be- come charged with sulphuretted hydrogen. From that mo- ment, their endosmosing action becomes liable to be destroyed. Thus a membrane acidified, salified, or alkalised, as much as it can be by the acid, saline, or alkaline liquid with which it is in contact, will no longer produce any endosmosis with the same liquid. In order to obtain an endosmosis, which will not cease spontaneously, a permeable partition must be placed in contact, on one side with pure water, and on the other with a liquid which has no chemical action on it. Thus if we put a solution of muriate of soda into an endosmometer closed with- a plate of clay, an endosmosis will be produced which will not cease. But if the partition of the endosmometer were membranous, the endosmosis would cease as soon as the partition became salified. Sulphuretted hydrogen puts an end to the endosmosis produced with a plate of clay, as well as with a membrane ; because, in both cases, it combines with the elements of the permeable partition. The extreme rapidity of this combination is the cause of the rapid manner in which that substance puts an end to the endosmosis. The same effect is produced by sulphuric acid ; but I repeat, that it will also be produced by all liquid substances, which are susceptible of combination with the elements of the permeable partitions of the endosmometer ; the only difference in that respect is in the rapidity of the combination. It is not easy to determine with exactness the physical causes of these latter phenomena; but it is evident that they depend upon the capillary action which is modified in the permeable partitions by the chemical 288 Ritchie on a Double acting Air-Pump. modifications sustained by the latter; and in fact, it is well known, that the capillary action experiences as much variation in its effects from solids of different natures as from different liquids. ON A DOUBLE-ACTING AIR-PUMP. By the Rev. WILLIAM RITCHIE, M.A., F.R.S., Prof, of Nat. and Exper. Philos. Royal Institution. O EVERAL attempts have been made to construct double- acting air-pumps; but from the fact that none of them are in use, we may conclude that the practical difficulties attending the construction of them were too great to bring them in com- petition with those in common use. The following contrivance appears to me sufficiently simple, and will obviously double the power without adding materially to the expense, and with very little additional friction. It consists of a barrel similar to Smeaton's air-pump, having a solid piston, with a piston-rod working air-tight in a collar of leather. The piston-rod has a hole drilled along its axis T — I E the whole length of the barrel, for the purpose of receiv- ing a brass rod, about the £th of an inch in diameter. The upper end of the rod is slit about an inch, and slightly opened, so as to act as a spring by its friction in raising and depressing Ritchie on a Double-acting Air-Pump. 289 the lower valve. To the lower end of the rod is fixed the conical metallic valve V, which is allowed to rise and fall about the tenth of an inch. A bent tube, T, connects the upper and lower divisions of the barrel formed by the solid piston. This tube is continued from the top to the plate of the air-pump. At the entrance of this tube into the upper end of the barrel, is placed a valve of oiled silk, opening inwards, to allow the air from the receiver to expand into the upper part of the barrel when the piston is depressed. Two valves, either conical or of oiled silk, are placed on the upper and lower ends of the barrel at F, E opening outwards, to allow the air in the barrel to escape into the atmosphere. When the piston is depressed, the conical valve shuts the communication between the barrel and the receiver, and the air is forced out at the valve F, whilst the air in the receiver rushes into the space above the piston to supply the vacuum thus formed. When the piston begins to rise, the conical valve, on the end of the brass rod, is raised, and the air from the receiver follows the piston till it has reached the top of the barrel, and expelled the air through the valve E. The next depression of the piston performs a similar office, and thus the full of the barrel of air, of the same density as that in the receiver, is at each stroke expelled, and conse- quently the exhaustion will go on with twice the rapidity of that produced by a single barrelled air-pump of the same size. Instead of the hollow tube for the piston-rod the wire might be made to pass through the piston, as in the French construction, with two conical valves on the extremities ; but the construction I have described seems to me the least liable to objection. ON THE METHOD OF OBSERVING THE FIXED LINES IN THE SOLAR SPECTRUM. BY J. T. COOPER, Esq. AS many with whom I am acquainted have sought in vain ~^ for those dark bands which occur in the solar spectrum produced by prismatic refraction, usually known by the appel- 290 Cooper on the Fixed Lines lation of Fraunhofer's lines; and as I have never seen, in any work, the precise method described that is necessary to be employed for their successful production, it occurred to me that a description of the instrumental means I adopt might not be unacceptable to some of your readers, and enable those of them who have more opportunity than myself, and are desi- rous of pursuing the investigation into the cause of their pro- duction, to proceed in their researches without the loss of time consequent on the experiments of any kind, where everything has to be sought. It is, therefore, with this view that 1 have written, and endeavoured, if possible, to save a portion both of time and expense to those who may feel inclined to enter this rich field of inquiry, and to enable those who may wish to determine the refractive and dispersive powers of substances to do so with precision ; and, should you concur with me in the propriety of these suggestions, to request you to give them insertion in your useful publication. In article 422 of Mr. Herschel's admirable paper on Light in the Encyclopaedia Metropolitan a, he says that ' with glass prisms of our manufacture it would be quite useless to attempt the experiment.' An assertion coming from such high autho- rity is of itself sufficient to deter any one from making the trial ; and he recommends the substitution of hollow prisms, filled with highly refractive media, in lieu of the glass prism. With this assertion I am in some degree disposed to coincide, but certainly not to the extent he there intimates. True it is that not one prism in twenty is fit to be employed for the pur- pose; yet I have obtained several of British glass, both of flint, plate, and crown, and of various refracting angles, that have shown not only the most prominent of the lines, but even those that may be considered as of the second and third order, and in such abundance, under favourable circumstances, that it would be no easy matter to count them : suffice it to say, that a good prism is necessary, and such can be met with, though not with- out some difficulty ; but neither its size, as respects its length, the breadth of its sides, the refracting angle, nor the kind of glass of which it is made is a matter of much moment*; yet * I have in my possession equilateral prisms of flint, plate, and crown glass, which are only three-quarters of an inch long, and the sides less than three-tenths in the Solar Spectrum. 291 the preference is to be given to one of flint glass with a large refracting angle (say 50° or 60°), because of its high refractive and dispersive powers ; all that is required is, that it should approach as near to perfect homogeneity as possible. A few streaks running parallel to the refracting edges may be disre- garded ; but if they are thrown into waves or curved lines, by injudicious workmanship, the prism is utterly useless for this purpose. Such a prism being obtained, let it be placed twenty, thirty, or more feet distant from, and with its refracting angle parallel to a very narrow linear opening in the window shutter of a darkened room : such an aperture or opening may be con- veniently formed in a piece of tin foil, or thin sheet lead, by the point of a sharp penknife ; and means must be taken to illumi- nate this aperture either by the rays of the sun reflected from the surface of a plane mirror, or by the light from a bright sky : the former is decidedly to be preferred ; that part of the solar miscroscope which is employed for a similar purpose when that instrument is used, will be found very convenient for this. The prism being placed in the beam of light transmitted by the aperture, either in a vertical or horizontal position, and its re- fracting angle as nearly parallel as possible to the aperture, turn it round on its axis until the refracted spectrum of the illumi- nated aperture formed by the prism appears to be stationary ; the prism is then in the position of minimum deviation, and the most favourable one for the production of the lines. If the spectrum be now carefully examined, a number of narrow black stripes will be seen crossing it at various distances from each other ; but as there is some difficulty in seeing them with the unassisted eye, on account of their minuteness, it is better to employ a telescope for the purpose, which, however, need not be of large dimensions, nor possess very high mag- nifying power ; the one I generally employ for this and similar purposes is J/6 inch aperture, and 18 3 inches focal length, mounted on the common portable stand, and has amplifying broad, with which I have seen the lines very distinctly ; also in a small triangular prism of rock crystal, with its refracting angles parallel to the axis of the original prism, I have seen the lines both in the ordinary and extraordinary spectrum of the aperture perfectly sharp and well-defined. 202 On the Fixed Lines in the Solar Spectrum. powers from 15 to 130 times, the object-glass of which may be placed as near as may be convenient to the prism, and a power of 40 or 50 times selected for the occasion ; when, how- ever, the adjustment of the focal length of the telescope is made to see the spectrum perfectly sharp and distinct at its edges, the dark lines will be seldom seen, or, if seen at all, but very faint and indistinct ; but if the drawer, or eye-piece, of the telescope be pushed in about half an inch, they will then be seen to perfection ; and by a nice adjustment, I have seen the major part of the lines nearly as sharp and well defined as the spider lines in the micrometer, employed for the measure- ment of their distances from each other. Lambeth, 8th October, 1831. ON THE ACOUSTIC FIGURES OF PLATES. By Professor STREHLKE. TN the second Number of the 8vo. vol. of Gilbert's Annalen, •*• Professor Strehlke communicated some very interesting ex- periments on this subject, which led him to conclude, 1. That acoustic figures are composed of curves ; and 2. That these curves do not intersect each other. And as Chladni had expressed some doubts on the accuracy of the experiments, (chiefly on account of their having been made with metallic plates,) Professor Strehlke afterwards repeated them on glass plates, and convinced himself of the correctness of his former experiments, and of the opinion to which he was led by them. The difference between the figures on metallic and on glass plates, says Professor Strehlke, when speaking of his late experiments, is very trifling ; and if the ex- periments are made with sufficient accuracy, the above result will be equally proved by the figures on either, but the lines are much more distinct on ground-glass plates, metallic plates, or glass plates covered with leaf gold, than on plates of polished glass ; and when he used a plate of the latter kind, but covered on one side with leaf gold, the distinctness be- Strehlke on the Acoustic Figures of Plates. 293 tween the two figures was very different, so much so that whilst, on the one surface, the curves evidently came only near each other, it was doubtful whether the lines on the other surface were intersected or not. Great attention is further to be paid to other circumstances which might influence the ex- periment, for the least change of temperature, a very slight degree of humidity, the commencement of oxidation, or any external agitation in the vicinity of the plate, is sufficient to disturb the formation of distinct figures. The quantity of sand * is also of great importance in that respect, and ought not to exceed above three or four grains on a square line ; the bow must be moved up and down steadily, and until the figure has ceased to undergo any further change ; and if the figures are to be measured, it is indispensable to reproduce them as long as they are not formed by one row of grains only, the joint central line through which may then be regarded as the quiescent line ; for if there were several grains, three, for in- stance, we should by no means be justified in considering the middle one as the representative of the quiescent line, as either of the two others might in reality stand for it ; for it is as pro- bable that one of the outer grains is balanced by the two others, as that the middle one is fixed to the two outer grains, &c., for that the plate rests in mathematical lines is, we believe, universally admitted ; and although sometimes, if much sand be used, broad lines are formed, the outer rows may always be seen to move as long as the plate sounds, whilst one line is completely quiescent. In* the following experiments the plates were supported on one side only, either on a vertical wooden bar with a small piece of cloth at the point of contact, or merely on the spread fingers of the left hand ; either of these two methods is pre- ferable to the use of the screw, which scarcely admits of the reproduction of the same figure ; for the least difference in the tension or in the plane where the plate is fixed, changes the figure, &c., which is not the case if the plate is supported in the manner above described, where it is sufficient that the * Professor Strehlke always used sea-sand, the grains of which, under the micro- scope, appeared as spheroids from 0"'.U3 to 0"/.U5 diameter, 294 Strehlke on the Acoustic Figures of Plates. resting point be nearly the same, in order to produce the same figures. The lines were measured by a scale of sufficient accuracy, to convince Professor Strehlke that the results were correct to the 2lf wood and liber, approach each other laterally, and are united at various distances ; so that the radii, or rather the medullary plates which separate them, have their length fre- quently interrupted by reticulations. This disposition, although general, is not universal : thus, in the vine and the cimis, the me- dullary radii form very long continuous plates without interrup- tion. M. Brogniart has made the same observation in all the menispermoe which he has been able to notice, as well as in the ligneous ranunculi, such as the clematis, in the aristolochia, and in the pipera. It might be hence concluded, that the structure belonged generally to creeping or climbing plants ; but the author, not hav- ing found it in the Bignojiia, periploia, honeysuckle, ivy, &c. ; and having observed it in the berberes, is induced to suppose it a charac- teristic, independent of the manner of growing, and having relation 2A2 346 Proceedings of the to the organization peculiar to certain families. Thus, therefore, the continuity of the medullary radii, from one articulation to another, may be considered one of the distinguishing characteristics of the plants above mentioned. With the exception of the clematis and aristolochice, which show it clearly at every age, this characteristic can only be observed in the young stems. M. Brogniart then re- marks, that the greater part of climbing plants have the stem almost entirely composed of vessels of so large a bulk as to be visible to the naked eye on the transversal section, which appears full of holes, like a sieve. This characteristic, which is peculiar, not to the family, but to the mode of growth of the plant, is considered by the author as a necessary consequence of the small volume and great length of the stem, which bears numerous leaves of a large size, because these leaves occasion a profuse transpiration, and therefore require a struc- ture of stem which will admit of a rapid passage of the sap, to supply the loss occasioned by the transpiration. M. Brogniart then details the remark which he has made on the internal organization of the vine, the clematis, and the aristolochia, the most important of which is the elliptical or oblong form of the section of the pith in the last named family. The author also establishes that, in the menispermee, the liber, or fibrous part of the bark, always remains in the same state that it was in during the first year, not increasing in any manner. Thus the cambium, which is interposed between the wood and the bark, instead of being divided as usual into two beds, the one of wood and the other of liber, is here entirely united to the ligneous body. He has also remarked that, in the internal structure of the stem of the menisperime, the ligneous body is divided into several concentric layers, perfectly distinct from, and independent of each other, each of which is the produce of several years, and that the new beds are frequently entirely wanting on one side of the stem, which is thus left naked. The pipera also offers some re- markable characteristics, particularly, 1st, the formation of new ligne- ous fascicules between those which primitively composed the ligneous ring surrounding the pith, by which the diameter of the medullary canal is increased, and 2ndly, the existence in the interior of the pith of fibrous fascicules analogous to those of the ligneous body, the number of which increases every year. M. Brogniart remarks, in conclusion, that comparative anatomy ought to be the basis of the classification of vegetables, as well as of that of animals ; and that the true charac- teristics of the organization of a plant are rather to be found in the body of the stem which produces the leaves and flowers, than in those leaves and flowers which are but the offspring of, and dependent on the stem. The reporters, although not disposed to believe that the internal analysis of the organs can ever be of the same importance in botany as it is in zoology, agree with the author that it must always be a source of interesting and important investigation. The report concluded with the highest eulogium on the talents and industry of M. Brogniart, and the recommendation of the insertion of the essay Academy of Sciences in Pans. 347 in the ' Recueil des Me'moires des Savans Etrangers,' which was ordered by the Academy accordingly. Fecundation of the Orchidece and Cisti (Cistinus). — On the 1st of August, Messrs. Cassini and Auguste de St. Hilaire made a report on a memoir by M. Adolphe Brogniart on the above subject, of which the following is an abstract. The object of the memoir is to explain, the mode in which the pollen acts on the stigmata, and the manner in which the fecundating fluid passes thence to the ovary in these two families of plants, the reproductive organs of which are not formed in the usual manner, with a view to strengthening the theory formerly promulgated by him as to the general mode of fecundation of plants. The pollen of the orchis is agglomerated in divided and subdivided masses in such manner that the last groups are composed of three, four, or five spherical grains. When these masses fall on the stigma, some of the grains are separated from the rest, and fix themselves on that organ. Each of these grains soon produces a membranous tube, which penetrates into the stigmatic tissue, formed of utriculi, elongated, free, and only united by a viscous liquid. In the epipactes, the pollen is pulverulent, formed of small aggre- gations of four spherical grains, which remain always united, and which, when they fall upon the stigma, give birth to very long tubu- lar appendages which penetrate deeply into the stigmatic tissue. The ovary of the Orchideae offers internally a simple cavity, having three longitudinal projections, each divided into two laminae ; these are the placentae, which have on their edge an infinity of ovula, so disposed, that the opening through which the fecundating fluid ought, according to M. Brogniart's theory, to reach them, is dia- metrically opposite to the point by which they are attached to the plant. This appeared an astounding objection to the theory, but M. Brogniart explains it thus. The stigmatic tissue is continued in the axis of the column which constitutes the style j it is there, at the summit of the cavity of the ovary, divided into three faisceaux, each of which is subdivided into two filamentary bands, which are applied to the two laminae of each placenta, and as the separate filaments which form these bands are twisted or folded back in festoons, which penetrate between the ovula, and often appear to extend quite to the orifice at their extremity, the stigmatic tissue serves as a conductor to the fecundating fluid, which is thus enabled to attain the orifice at the extremity. The family of the cisti (cistinus) offers, from the ordinary position of the orifice of the ovula, the same objection to the theory of the fecundating fluid proceeding from the stigma to the interior of the ovary by means of that orifice ; but M. Brogniart remarks, that when the orifice of the ovula is opposite to the point of junction with the plant, these ovula are placed on a very long umbilical cord, which is tortuous or bent back, so that the disengaged and open extremity of the ovulum is in contact with the sides of the ovary, of the partitions, or of 348 Proceedings of the the placentce, a fact which is quite sufficient to establish the possi- bility of the communication, as the stigmatic tissue, the conductor of the fecundating fluid, could very easily creep along the sides of the ovary until it came in contact with the orifice. And, in fact, it fre- quently happens, that in some Helianthema, the umbilical cords of which are not so regularly bent back as to bring all the ovula in con- tact with the placenta, a number of ovula, which have become abor- tions, are found in the fruit when ripe, their vestiges remaining dis- persed among the perfect grains. The following facts, pointed out by M. Brogniart, are still more remarkable. In the Helianthemum l&vipes et thymifolium, the ovary contains six ovula, attached near the summit of its cavity to the three pla- centae by cords so short as to be unable to bend back. But in this case, the orifice of the ovulum, instead of being, as in the other species, opposite to the point of junction, is almost close to it, and is prolonged in a small tube which is applied exactly to the base of the style at the point of termination of the extremity of the conducting tissue. In other species, such as the Helianthemum Mgyptiacum et Niloticum, where the numerous ovula are inserted on placentae, which are parietal, not projecting, and supported by cords nearly straight, so that their open extremity cannot be brought into con- tact with any point of the internal sides of the ovary, M. Brog- niart has discovered that the conducting tissue, which occupies the axis of the style, is prolonged downwards to the middle of the cavity of the ovary in a bundle, divided and subdivided into a number of fine and floating filaments, which can easily carry the fecundating fluid to the orifice of the ovula. From these facts, M. Brogniart concludes, that whatever may be the structure of the pollen, its seeds always produce a long membranous tube, which penetrates between the utriculi of the stigma to deposit the fecundating matter in its tissue, and that, notwithstanding any modifications in the structure of the ovary, the stigmatic tissue or conductor always penetrates to it, and is there disposed so as to be placed, by some means or other, in contact with that part of the ovulum which, being open, allows of the introduction of the fecundating matter. On the truth of this theory, however perfectly it may appear to be supported, it is not the province of the reporters to pronounce; but the facts adduced have been verified by them, and found to be equally new, interesting, and exact; and the importance of these facts is sufficient, independent of any hypothesis, to entitle the memoir to be inserted in the ' Recueil des Me'moires des Savans Etrangers.' Abortions and Irregularities of Flowers. — On the 1st of August Messrs. Cassini and Mirbel made a report on the Memoir of M. de Jussieu on this subject, of which we gave an account in our last Number (page 133). After having analysed the memoir, the reporters remark, that by a singular chance M. Adolphe Brogniart had examined nearly the same question as M. de Jussieu at the same Academy of Sciences in Pans. 349 time, and arrived at a similar result. (Vide Report, July lltli, on his Memoir, page 338.) While the memoir of M. dc Jussieu was under the consideration of the reporters, he forwarded to them an- other and more detailed memoir, containing a great variety of inte- resting observations and illustrations of the family Malpighia. The ovuhi of this family are different in their mode of development from all those with which we are acquainted ; they cannot, therefore, be referred to either of the three classes, Orthotropes, Anatropes, and CampulitropeSt as they appear to participate of all these forms. The ovula of the Hippocastanq are entirely anatrope. Two in each ovary, they present the remarkable characteristic, that in developing, one breaks out (se renverse) from top to bottom, and the other from bottom to top. The ovula of the Acerimts are also anatrope, but not so decidedly so as those of the Hippocastana. The Camarea hir- suta, and the Camaria affinis, produce two kinds of flowers, the one conspicuously situated at the upper part of the stem, having four large petals, six well-conditioned stamina, and three fecund pistils ; the other very small, hidden in the angle of the lower leaves, having no corolla, but one indehiscent stamen, no pollen, and two ovaries, generally without style or stigmata, yet producing good seeds like the ovaries of perfect flowers. The father of M. Adrien de Jussieu, in his Genera Plantamm, had divided the family Malpighia into two secondary groups, characterised the one by pulpy, the other by winged fruits ; but M. Adrien de Jussieu remarks, that there are genera with capsular fruits, which belong to neither of these sections, and form a transition from one to the other. M. de Candolle had added a third group, under the name of Malpighia Monostyla; but the supposed single style is, according to M. Adrien de Jussieu, nothing but a bundle composed of several styles fas- tened together, and proceeding from an equal number of united ovaries ; and the genus in question contains species, in some of which the styles are united quite to the summit, while in others, they are separated almost down to the base. The author, therefore, rejects both these divisions, and considering that the genera are only distinguished from each other by small and graduated differences in the degree of abortion, he prefers considering the family as a whole, without establishing any artificial division into tubes or groups. The memoir details the particulars of sixteen known and eight new genera, in which he has added to the 195 species before described, 90 hitherto unknown, or not supposed to belong to the family. The author avows his intention of re-arranging all the botanical families ; and if immense materials, indefatigable research, and acute observa- tion be sufficient to enable him to do so successfully, he is sure to triumph. If M. de Jussieu's theory of organization be open to some doubts, his efforts to dispel those doubts have been highly advan- tageous to science, as they have elicited a number of curious and authentic observations on the floral organs of the Malpighia and kindred families. 350 Proceedings of the Family of the Chenopodia (Chenopode'es). — At the same meeting, M. Auguste de St. Hilaire read a report on a memoir by M. Alfred Moquin on this family, — one of the least known in the vegetable world. This memoir, which is the first of a series, is devoted to the examination of the genus Sueda and the other Chenopodia most allied to that genus. The genus Sueda had been confounded with the Chiropodium and the Salsola, until Forskal proposed to class them in a separate group under the above name ; but it has never, until now, been accurately described by any naturalist. The Sueda with ligneous or herbaceous stems, and fat and succulent leaves almost vermicular or cylindrical, grow on the borders of the sea or of lakes ; they will always afford soda by incineration ; but as the presence of this substance in the tissue is accidental, it will disappear when the plant is cultivated at a distance from salt water or marshes M. Moquin enters into very long and minute descriptions of the various organs of the plant, and affords some remarkable explana- tions of anomalies in different species, particularly the existence of the perisperma in the A triplex, the Beta, and the Chenopodium, and its non-existence in the Salsola, the Camphorosma, the Ana- basis, &c. ' The species of liquor,' says M. Moquin, ' in the midst of which the embryo of the Salsola at first floated, becomes entirely absorbed by it. When this embryo has attained its full growth, it is larger or longer than that of the Chenopodia, which have seeds abundantly albuminous ; it is more advanced, and has the tissue and colour of a little plant. Consequently a seed of Chenopodia, which has no perisperma, only differs from an albuminous seed of the same family, inasmuch as it has already absorbed its perispermic nourishment, and its embryo is rather more advanced in its growth. It results also from this observation, that the moment of maturity of seeds is not in all plants precisely that at which the embryos have attained the same degree of development. Thus a grain or seed of Sueda, having a spiral embryo, but without perisperma, is not analogous, as to its growth, to a grain of Amerind which has just left the parent stock ; the latter at its maturity resembles a seed of Sueda, which is still at a certain distance from maturity.' In the Chenopodees which have a perisperma the embryo is white ; in those which have none it is greenish. The Sueda, however, are excep- tions to this general rule, as their embryo is white, and they have no trace of perisperma. The reason of this, according to M. Moquin, is, that the Chenopodia which have a perisperma, generally have a double integument, the thick and crusty exterior of which allows no passage to the light, and the embryo therefore remains white; whereas the others have only a simple, membranous, thin tunic, the tissue of which allows the passage of the rays of light, which produce the green colour. The Sueda, although without perisperma, have an exterior crusty integument like the Anserince, and the embryo there- fore does not become coloured. The genus Shangmia (which, as well as the genus Schoberia, was Academy of Sciences in Paris. 351 first distinguished as a separate genus by M. C. A. Meyer) forms a singular exception to the rest of the family of the Chenopodia in having a semi-infere fruit. M. Moquin supposes the adherence of the pericarpium to be owing to an intermediate discus between the ovary and the calyx. The reporter, without rejecting this explana- tion, remarks that the consequence deduced is not a necessary one, as many plants present a large discus joined to the calyx, without having the ovary otherwise than free and disengaged. The Sueda, the Schoberia, and the Shanginia form a little tribe in the family of the Chenopodia^ the distinguishing characteristics of which are a white or whitish embryo, spirally turned, usually without perisperma, and always surrounded by a double integument, the ex- terior of which is crustaceous. The various plants comprising this tribe are described by M. Moquin with great accuracy and minute- ness ; but it is obviously impossible for us to follow him into this detail. The reporter observed that the work merited the full appro- bation of the Academy, and urged the author to continue his re- searches on the other tribes of the same family*. Decoloration of Leaves ; Vegetable Nutrition. — On the 8th of August, M. Dutrochet read an elaborate memoir on the above sub- jects, of which the following is an analysis. It is well known that when light is excluded from any of the vegetable kingdom the leaves lose their green colour, and become of a yellowish-white. The phy- sical cause of this is the loss of carbon, which, when the action of the light no longer fixes it in the tissue of the plant, is poured out into the atmosphere in the shape of carbonic acid, and the plant, deprived of the substance to which it owes its green hue — the sign of life and health — languishes into a morbid paleness. But the loss of carbon is not the only cause of the change of colour ; it is also produced by the exhaustion of the soil in which the plants are growing. Thus the leaves of a plant in a garden-pot will, if not watered with manured water, lose their green tint, and become white about three years after they have been allowed to remain in the same mould. Three years is mentioned as an average period, but the time will be greater or less according to the degree of nutritive principle and to the volume of the mould in the pot. An example illustrating this fact occurred a short time since. A gentleman, whose house was situated on a calcareous rock, dug large holes in the rock, filled them with earth, and planted peach trees. These trees had every atmospheric advan- tage ; the fissures of the rock allowed free passage to the rain-water ; and from their full exposure to the sun and light there could be no deficiency of carbonic acid ; yet, after flourishing a few years, the leaves began gradually to change colour, and ultimately, when, from * M. Mo