Saey: wet 4 a t d a ae L$! Evinburgh = JOURNAL OF SCIENCE, - _ 2 CONDUCTED BY DAVID BREWSTER, LL.D. F.R.S. LOND. AND EDIN. F.S.S.A. M.R.I.A. - CORRESPONDING MEMBER OF THE INSTITUTE OF FRANCE} CORRESPONDING MEMBER OF THE ROYAL PRUSSIAN ACADEMY OF SCIENCES; MEMBER OF THE ROYAL SWEDISH ACADEMY OF SCIENCES; OF THE ROYAL SOCIETY OF SCIENCES OF DENMARK; : OF THE ROYAL SOCIETY OF GOTTINGEN, &c. &c. VOL. III. NEW SERIES. APRIL—OCTOBER. at | ear ‘4 $ 7 q THOMAS CLARK, EDINBURGH: T. CADELL, LONDON: AND MILLIKIN & SON, DUBLIN. M.DCCC.XXX. a BH { 2 ies a WARY 28 eats: . VER CMA WER AO! ROL EA Ame Kod hi ies j owen, ahs eh tee aire tow bast "th Cn ¢ asker em ee ce wn NAR N biphe hi inte by A lees LEON ROLE IE ai JOLOO- DEAT A: Ts ¢ ' be : eR Br) : eM: He aida fs | ARE iin, ho i HOH nis t ae MOU MOL wlll rid UG. CONTENTS OF THE * EDINBURGH JOURNAL OF SCIENCE. No. V. NEW SERIES. ctaitietiaiaiata ee ART. I. Yearly Statement of the progress of Physical and Chemical Science, delivered on the 3lst March 1829. By Jacoz BERZELIUVs.—Ars- Page berattelse om Framstegen i Physik och Chemie Afgiven den 31 ¢ Mars 1829, af Jac. Berzelius, j ° 4 II. Experimental Inquiries concerning the Laws of Magnetic Forces. By D. Snow Harris, Esq. of Plymouth. Communicated by a Cor- respondent, ° . : ° III. Notice of the performance of Steam-Engines in Cornwall for January, _ February, and March 1830. By W. J. Henwoon, F. G. S., Mem- ber of the Royal Geological Society of Cornwall. Communicated by the Author, ‘ , ES E -1V. Notice of experiments with Laurel Oil. By Dr Hancock. Com- municated by the Author, . . ‘ V. Account of a curious phenomenon of revolving motions, produced by the combination of Alcohol with Laurel Oil. By Dr Hancocx. ~ Communicated by the Author, : ‘ . VI. Description of a simple, cheap, and accurate Rain-Gage, calculated to show the depth of rain falling around it to the ten-thousandth part ofan inch. By MaTTHEw Apam, A. M., Rector of the Academy 46 46 51 of Inverness, and Associate of the Society of Arts for Scotland. Com- . municated by the Author, . . VII. Observations on the National Encouragement of Science, and on its Encouragement by learned Societies, with observations on the general state of learned Societies in England. By Cuaries BABBAGE, Esq. M.A, F.R.S.L. and E., Lucasian Professor of Mathematics, Cam- , bridge, : : : - VIII. Experiments on the variations to which Magnets are incident when exposed to the Solar Rays. By Professor F. ZANTEDESCHI, IX. Inquiry into the cireumstances under which the Remains of some Fossil Animals were accumulated in the volcanic soil of the Velay, in France. By S. HiBBert, M. D., FR. S. E., &c. &e. Communi- cated by the Author, . X. Account of Experiments on the Elastic force of Steam up to twenty- — - four Atmospheres, made by order of the Academy of Sciences of Paris, a . 58 76 90 li CONTENTS. XI. On Inscriptions in living Trees. By Dr C. A. AGARDH, Professor of Economy and Botany,at Lund. Translated from the Swedish To James FP. W. Jouxston, A. M. XII. Note on a Physiological phenomenon seodiogeh by, Blectricite, ce ' Dr Er. Martantnty Professor of Natural Philosophy at Venice, XIIi. On the Influence of the direction of Winds on the Electricity which accompanies the condensation of aqueous vapours in the atmosphere. By Professor SCHUBLER, Tubingen, yu arn 116 XIV. Abstracts, with occasional remarks; from a Main regarding the Human Bones and objects of Human Fabrication discovered in solid beds, or in alluvium, and upon the epoch of their deposition. By M. MARCEL DE SERRES, Professor of Mineralogy and of Sa to the Faculty of Sciences of Montpellier, . 121 XV. On the double Chlorides of Gold. By James F. W. sichmantreiiitg nA A. M. Communicated by the Author, 6 | 131 XVI. Observations on some passages of Dr Lardner’s Treatise on Mecha- nics. By the. Reverend W. WHEWELL, M.A., F.R. S. Professor of Mineralogy, Cambridge. In a letter to Dr BREWSTER, 148 XVII. On the Improvement of the Microscope. By H. CoppINe6éTOoN, M: A., F.R.S. Fellow of Trinity College, and of the ib. 325 CONTENTS. lll Page Il. CHEMISTRY. 2. Mineral Kermes. 3. Phosphuret of Sulphur. 4. Chlorides, Lodides, and Bromides of Sodium. 5. Effects of heat upon copper ores. 6. Preparation of Phosphorus. 7. Hydriodic Ether. 8. Seleniuret of Paladium. 9. Hu- ' raulite and Hetepozite. 10. Black Blende of Marmato. 11. Sulphuret of Silicium. 12. New compound of Chlorine, Phosphorus, and Sulphur. 13. Atomic weight of Iodine and Bromine, ° ; 356—360 Ill. NATURAL HISTORY. ZooLocy.—14. Queries respecting the Natural History of the Salmon, Sea- Trout, Bull-Trout, Herling, &c. 15. The Capercailzie. 16. The Portuguese Man of War. ; ; : 361—364 _ IV. GENERAL SCIENCE. 17. Burning Coal Mine at New Sauchie. 18. Hay converted into a Siliceous Glass by Lightning. 19. Application of Zinc to Roofing of Houses. 20. M. Utenhove on Spherical and Parabolical Specula for Telescopes. 21. Iron Trade ot Great Britain. 22. Explosion at the bottom of a Well at Bologna. 23. Destruction of Live Stock by Wolves in Russia. 24. Supposed Series of Sub-marine Banks from Newfoundland tothe English Channel. 25. New Islands on the Coast of Japan. 26. Agitation of the Sea in the Channel, and Earthquakes in Italy. 27. Great Rain in Perth on the 3d August 1829. 28. Earthquake at Bogota on the 17th June, 29. Earthquake in the Ne- therlands, 23d February 1828. 30. Prizes, . 5 364—370 XXIV. List of Patents granted in Scotland since September 23, 1829, 370 XXYV. Celestial Phenomena, from October Ist, 1830, to 1st December 1830, 373 XXVI. Summary of Meteorological Observations made at Kendal in June, July, and August 1830. By Mr SamuEL MarRsHALL. Communi- cated by the Author, P 374 XXVII. Register of the Barometer, i hiaenustivehers and Rain-Gage, kept at Canaan Cottage. By ALEX. ADIE, Esq. F. R.S. Edinburgh, 376 Be Eds i < Ait’, ) is \ » otal: Dies ths. Tle fete” ese Hoe . ‘his te eeu 4s ihe rep ebay: ie ie Sas sit Lis scsobuag eae RED cpt sae vere d i nt _ sad thas aL gat of OC at oes itt eee tis vi Agta 9 na yao * 4 a Masi ic sere Abi Ste 5. em Sa us npaik A: iss in RC aida. u stp es Mi a et ob wre i yy bee yi nieeli at. pai Om vm Edin? Journalot Science. Series Voll. SS ss a Lana! : a“ | = : ee a } La Lazare sculpt WIE Sy FL EN MR aE TN |e AMee Oar Miter Ay een Py P [ee PORE Or Edin? Jour: of Science N. Series Val. D A. p. 256.262 Uy IY x \f | 7 ogi Bae) lL ae ce. ko ey TPR ih PARDON THE EDINBURGH JOURNAL OF SCIENCE. Art. l.—Yearly Statement of the progress of Physical and Chemical Science, delivered on the 31st March 1829. By Jacos Berzevivus.—Arsberattelseom Framstegen i Physik och Chemie Afgiven den 31 Mars 1829, af Jac. Berzelius. Tue yearly statements of this eminent chemist, though gene- rally late in reaching this country, are always acceptable to scientific men. ‘The yearly reports of the French Academy are confined to their own labours; those drawn up by the several Professors connected with the Academy in Stockholm - embrace the entire range of annual discovery.. Each Profes- sor marks every advance in his own department, and records it in his report. Thus zoology falls to the lot of Neilsen, the mechanical sciences to Pasch, and chemical physics to Ber- zelius. Nor are these statements mere extracts from the jour- nals of the preceding year; they contain much valuable criti- cism, from which the importance of the researches of others may in some measure be estimated, and their influence on the state of knowledge more clearly comprehended. — It is this lat- ter portion of the work which gives its chief value to the reports’ of Berzelius. Standing in general estimation at the head of his science, much interest naturally and justly attaches to his annual criticisms. While his statements serve as landmarks, showing the precise length to which discovery goes in each NEW SERIES. VOL. III. NO. I. JULY 1830. A 2 Berzelius’ s yearly statemen# of the progress of branch of the science during each successive year, they also compare former knowledge with that to which we now attain, distinguishing what is really new, and assigning to every one his due merit,—and, holding the balance between conflicting opinions, concerning which experiment pronounces nothing de- cisive, endeavour to point out what may be the true state of things by the deductions of a wide analogy. The present report, as the title bears, was delivered on the last day of March 1829, but, owing to circumstances which kept back the other reports, the volume of which it forms a part was not’published till the month of October. It is gene- rally translated into the German within two or three months after its appearance, and often into French perhaps as many later ; but, excepting occasional extracts taken chiefly from foreign journals, little has appeared in our language regarding the yearly statements of Berzelius. An analysis of this work will, therefore, we conceive be highly interesting to our read- ers, and we shall endeavour to make it more so, by confining our attention chiefly to the interspersed remarks of the author, and to experimental results which have not been already re- corded in this Journal. The report embraces first Physics,and Inorganic Chemistry, next Mineralogy, to which succeed Ve- getable and Animal Chemistry... We shall follow him eg these several departments. ! After some notices regarding sound and. light, he comes.to the subject of electricity, on, the phenomena, and theory of which so many able men, are at present engaged. Of Mr Ritchie’s experiment on iron raised toa white heat, showing that a ball at this temperature has the same dispersive power long known to belong to metallic, points, he observes, “‘ Ritchie seems tu have left out.of view. the influence of iron at a white heat on the surrounding atmosphere.” | But. his most important remarks are in reference. to the An pers of De la Rive in the 37th and 39th volumes of the Annales de Chimie, on the developement of electricity in the pile. In, these papers De la Rive has shown, by a series of ingenious and admirably conducted experiments, thatthe electrical theory, or theory of contact advanced by Volta, cannot. be the true theory of the galvanic pile; and embracing, therefore, the Chemical and Physical Science. 8 other, the chemical theory, he endeavours by the aid of it to explain all the phenomena he has observed, while, vice versa, he contends that these experiments prove the chemical theory. His investigations, in short, are not made in search of a true theory, but assuming one of the two received theories to be true, his experiments, and many of them are exceedingly inte- resting, and devised with much skill and judgment, are intend- ed to show the chemical to be the true one, This latter theory, indeed, is the simpler, and that which has the easiest and more visible proof on its side, and which, from the zeal of its advo- cates, is at present making the greater way. Still there are some few phenomena which it fails satisfactorily to account for, and which have led some philosophers, without rejecting the great influence of chemical action, to refuse it thesole agency in the developement of galvanic electricity. Among these is Berzelius. Though in his treatise upon the “ Z’heory of the Electrical Pile,” published in 1807, he advocated the chemical theory, yet later experiments have convinced him, that, how- ever intimate may be the connection of chemical action with the phenomena of galvanism, yet that they have not their ori- gin in this action, or at least cannot in all cases be accounted for without the co-operation of the conducting power suppos- ed in the electric theory. ‘To such of our readers as take an interest in these theoretical discussions, we would recommend a reference to the first part of Berzelius’s Chemistry, where they are shortly discussed with the author’s usual sagacity. Among the experiments of De la Rive, Berzelius finds one equally opposed to both theories. ‘‘ If a glass tube be bent in the form of a U, into the one end of which is put sulphu- ric.and into the other nitric acid, so as to keep them unmixed, | - and if an arch of zinc and copper be so placed that the zinc shall be in ccntact with the former and the copper with the latter, no chemical action takes place in the sulphuric acid, but the copper is dissolved by the nitric; nevertheless the zinc is positive and the copper negative, contrary to what ought to follow if the chemical action were the source of the electricity. To remove the powerful objection to his opinion to which this seems to give rise, he shows that if the arch consist of one metal only, the direction of the stream is still the same, though : Bb ai3 4 Berzelius’s yearly statement of the progress of its intensity is less. Hence, says he, it is clear that when a single metal produces a stream in the same direction as two, the contact between two, copper and zine, cae ut have been the cause of the stream ; but in his eagerness to overthrow Volta’s theory, De la Rive seems to have forgot thathe result of the experiment controverts as strongly the opinion he wishes to — - support, that'the chemical action is the primary cause of the . electrical phenomena, since while the chemical action is in the — one acid, the direction of the chemical phenomena is from the other. He endeavours to explain this on the principle, that the electrical stream finds greater difficulty in passing from the copper to the sulphuric acid, than from the latter to the nitric acid, bat that is to let a slight hindrance overcome a meee action.” ; But it is obvious that this experiment’ affords another shila: ment still in favour of the conjomed influence of the two gene- rally assigned causes as held by Berzelius. For if when the arch of metal is of copper alone the electricity is of small inten- sity, and yet without any addition to the apparent chemical action, becomes of greater intensity on merely replacing a por- tion of the copper by a wire of zinc, it is evident that the cir- cumstance of contact has an influence, if not in the primary developement of the electricity, at least in making it sensible, Or if the action of the nitric acid upon the copper appear to in- erease by making the arch in part of both metals’ while at the same time the electrical mtensity is increased, it might even be presumed that the condact of the two metals influences the primary developement itself of the electricity. At all events, it dees seem, both from this experiment and from the pheno- mena of the compound piles described by Berzelius in his Lar. bok, which De la Rive has endeavoured, though unsatisfactorily, to explain according to his own views, that at present we can- not entirely account for all the appearances of bodies influ- enced by galvanic electricity by either of the theories taken alone. Mr Ritchie of Tain, in a paper from the Philosophical Transactions, inserted in this Journal, vol. u. p. 150, has brought forward one or two other experiments which he con- evives to be hostile to the chemical theory. While upon this a Chemical and Physical Science, 5 subject, we may take a glance at these experiments. .. Experi- ment third is hostile to the theory, because in a combination of two zine plates immersed in water, the addition of nitrows, acid to the fluid surrounding one of these plates induces. negative electricity upon that plate, instead of positive, as the theory supposes. Now of the trwe nitrous acid we know by the ex- perinients of Gay-Lussac, that when poured into water it is decomposed, forming nitric acid, hyponitrous acid, and deutox- ide of azote, in proportions varying with the extent of dilution. The greater the quantity of water the more nitric acid ,and deutoxide is produced, and the less hyponitrous, and vice versa. When nitrous acid, therefore, is poured into one of the cups, a series of chemical actions take place independent of that of the acid upon the zinc, and the result obtained by Mr Ritchie merely shows that the effect of the whole series is to produce such a change on one of the plates as to make it negative in regard to the other. When such complicated actions. take place, all of them involving changes in electrical state, nothing certain can be inferred affecting the truth or falsehood of the chemical theory. As the nitrous acid tends to form much hyponitrous, when the quantity of water is small, it would. be curious to see if the electricity developed in this case were the same as before; but the acid must be newly distilled as it speedily decomposes. If it have any shade of green, it already, according to Dulong, contains much nitric acid. This to us seenis a very probable solution of the difficulty, and we have been the more particular in stating it, because, though partaking in some degree of the views of Berzelius, we are desirous, if possible, to get rid of the anomalies in galvanic _ electricity, made known to us by the multiplicator ; and be- cause this is not the first anomaly which the action of nitrous acid upon metalshas presented. So long ago as 1790, Kier found that iron, after being subjected some time to the action of a mixture of nitric and nitrous acids, lost the power of precipitat- ing silver, which may again be restored by rubbing or filing its surface. This fact has more lately drawn the attention of Wetzlar and Fechner, who have shown it to be owing to a change of electrical state undergone by the surface of the me- tal, which would in itself be no anomaly, were it not that this ' 6 Berzelius’s yearly statement of the progress of surface continues still quite metallic. It is possible that inter- nal changes in the fluid, aided by, or independent of, the in+ troduction of the metal, may be the cause of the ORI as we have supposed in regard to Mr Ritchie’s experiment. - This is rendered more probable by what takes place in re- gard to another class of apparently anomalous cases. If a combination of iron and copper be plunged into a solution of a sulphur salt, as sulphuret of potash, the copper is at first negative, but after a short time becomes positive. Davy at- tributed this to the formation of a new solid body on the sur- face of the metal, by which its electricity is changed. And if, accordingly, the copper be removed from the liquid and wash- ed, it is restored to its former condition, is negative when again plunged into the liquid, and as speedily becomes positive. © All these anomalies, though they may not at present admit of the most satisfactory explanation, tend at least to prove the same thing, that unseen and unappreciable chemical actions in the fluid employed, due sometimes to the presence of the metals, ‘sometimes to the mixtures it contains, tend to modify, and sometimes entirely to change the nature of the electricity which is developed. Mr Ritchie’s fourth experiment is less exceptionable. The true explanation of it will probably be found in the chemical properties of tin, in relation to the acids. . We know that cop- per and iron, with a slight coating of oxide, are negative in re- gard to pure copper and iron. This is probably the case also with tin. Nitric acid speedily converts tin into an oxide; it requires, therefore, only that the aqua regia employed should have an excess of nitric acid to put the plate of metal in a con- dition to act as a negative body,—that the nitric acid should be in quantity sufficient to form a portion of oxide on the sur- face. The whole plate in this case will be negative, in regard to another clean plate, and the greater surface, that is, the grooved one will be negative in regard to the plain one, as in Mr Ritchie’s experiment. De Ja Rive has shown, that an elec- trical current may be established by one liquid and one plate of metal, having a smooth side and a rough one, which he brings as an argument against the theory of Volta. If Mr Ritchie has not seen this in the 37th volume of the Annales de Chemical and Physical Science. 7 Chimie, as seems to be implied by the similarity of ‘the intro- duction to his own paper, and his first experiment to some of the statements of De la Rive, he will find a reference to retti exceedingly interesting. | ~ Watkins has carried the simplicity of this combination of De Ja Rive still farther. He has succeeded in forming a pile of a perceptible tension, with plates of zinc alone polished on the one side, and rough on the other, without any moist conduc- tor. They are placed in a wooden frame parallel to each other, at a distance of one or two millimetres, so as to have a thin layer of air between each. The combination is air, rough zinc, smooth zine, air, &c. and the rough zinc is positive, as when the place of the air is supplied by a liquid. This has been explained like de Luc’s pile, by the oxidizing effect of the air, but it is difficult to conceive that such arrangements can owe their polarity to any chemical action upon the metallic surfaces, since Berzelius, in commenting upon this opinion of Wavy in his Arsberattelse for 1827, states, that he has kept a pile formed of tin and brass papers, in which the tin is the positive metal, in activity for eight years, and yet the tin paper re- mained to the last as pure and brilliant as when first employed. ‘And that the moisture of the paper which was supposed to be instrumental in causing oxidation has uo connection with the electro-motive agency, has been long ago shown by the experi- ments of Jager, in whose piles the papers were dried and sealed up with a non-conducting body, at the temperature of 140 Fahr., so as to be air-tight, and yet continued in activity. These phenomena cannot be explained without having recourse to something more than chemical action, “‘ which seems by no means necessary for the developement of the electrical elements in the dry pile. The absence of chemical phenomena may be remarked by the small quantity of electricity and the great tension, and their presence by the great quantity of electricity, and the small tension in proportion to it. Independent of che- mical phenomena, they may possibly depend upon the unequal conducting power of the metals employed, and their conse- quent unequal capacity for electricity in its distributed or po- larized state, which must be greater in good than 1 in bad con, ductors.” _ F 8 Berzelius’s yearly statement of the progress of ‘The phenomena detailed under experiment fifth were un- — expected, but we do not see that they are on that account hos- tile to the chemical theory any more than the similar facts, that a polished or rolled plate of zinc is negative in regard to an- other of the same metal, which is cast and unpolished. From these facts we should have expected, as Mr Ritchie seems to have done, that the hammered plate would be negative also, But it is positive, owing to the change of structure induced by hammering probably its being rendered more dense, so as to “present more points to the action of the acid. Had Mr Rit- chie shown, that, while hammering rendered .the plate positive; it rendered it at the same time less assailable by the acid, then he might have set it up against the chemical theory. That the hardening of steel, again, renders it negative is simply) an- other fact, valuable as such, but having no claim, that we can perceive, to,a place among facts hostile to a theory which shes in reality confirm. The apparent anomaly in experiment sixth is probably ow- ing in a great measure to the action of the hot iron upon the water, evaporation of which is generally connected with the developement of electricity. * Or it may be that by heating, a thin coating of oxide is formed upon the iron previous to plunging into the water, which, from the experiments of De la Rive, is sufficient to render it negative. We cannot at all agree with Mr Ritchie in the conclusions he draws from his seventh experiment: ‘‘ Since, he says, the zinc is dissolved without the assistance of oxygen from the water, it appears that the atoms of the acid have combined with the pure brilliant atoms of the metal, without the neces- sity of the metal being first converted to an oxide.” Now, if the zinc, as Mr Ritchie states, was dissolved by the dilute sul- phuric acid, without the evolution of hydrogen, which it would require repetition in a more delicate apparatus, as well asa * According to Becquerel arid Pouillet, this is not the case with perfect- ly pure water, but a minute portion of foreign matter in solution causes the evolution, now of the one, and now of the other electricity.—Since writing the above, we have conversed on the subject with Mr Kemp of Edinburgh, who informs us that he has made this experiment long ago with a hot plate, and has always accounted for it by evaporation. Chemical and Physical Science. 9 subsequent analysis of the solution to establish, still it would only show, that sulphuric acid, under certain circumstances, gives up an atom of its oxygen to metallic zinc, and forms with it afterwards a sulphite. According to this view, the results are no way inconsistent with the chemical theory, nor ‘“ with any of the generaliy received notions of chemists.” But the part of De la Rive’s papers which calls forth the chief remarks of Berzelius, is that in which he draws from his experiments conclusions opposed to the truth of the electro-che- mical theory of affinity. We shall give an outline of the ex- periments and desltitudns, and subjoin the observations of Berzelius. _ First, He shows that one metal and one liquid may prided a current, if one surface of the metal be smooth and the other rough or scratched. Second, That if a galvanic pair of copper and tin be dine into caustic ammonia, the copper is positive and the tin nega- tive, while if it be dipped into caustic potash, or a dilute acid, the tin is positive, as we might expect, @ priori, and the cop- per negative. The reason is, that in the ammonia the copper only is dissolved and not the tin. While in the potash ley, and diluted acid, the tin only is dissolved. This, says Berze- lius, is in my opinion the most interesting experiment he has brought forward, since ammonia and potash are liquids of the same kind, which, slestio-nhemically ought to act upon metals in-the same way- Third, Another well devised experiment consisted.in - ung. ing a small combination of lead and copper alternately in dilute and concentrated nitric acid. In the concentrated acid the copper was dissolved, and was therefore positive,—in the dilute ’ acid the lead, on the contrary, was acted upon, and the copper was negative. The result of many experiments is embodied in the following series, in which each metal is positive in re- gard to all those above it: . | Concentrated nitric acid.. - | Dilute nitric acid. Iron oxidized. Silver. Silver. _ Copper. Mercury. } Iron oxidized. Lead. | Iron. 1p Berzelius’s yearly statement of the progress of Copper. Lead. tse Iron. Mercury. , law Zinc. ‘Vin. . ALsh 3 ONiRg Tin, ; Zinc hale : The dissimilarities in these series are all so connected with the action of the acid on the different metals, that the deve.’ lopement of the electricity plainly flows from the chemical ac- tion, and not from the contact of the two metals, for other cir’ cumstances remaining the same, increase or decrease in the quantity of water present, cannot, according to Volta’s theory,’ be supposed to change the polarity. In like manner charcoal and platina in aqua regia give the platina positive, and in sul- - phuric acid of 100 or 150 the charcoal positive, according al- ways as the one or the other is acted upon. Iron also is posi- tive with arsenic in a dilute acid, but negative in fused caustic’ potash, because the iron is dissolved by the acid and the arse- nic by the alkali. From these experiments, besides other deductions which we pass over, he draws the following conclusions affecting the’ electro-chemical theory : ** In this theory, (the chemical theory of galvanism,) ds electric state of a hydro-electric pair is not derived from an electric principle belonging to each separate body in a way pe- culiar to itself, as is commonly understood when we say that zinc is positive in respect of copper, or that an acid is strongly negative, an alkali strongly positive ; but the electricity is des: rived from the action of a chemical agent on the surface of a solid body. It is this which separates the two electricities in’ a manner analogous to friction, percussion, and all the mecha-: nical actions which excite motion among a greater or less num-’ ber of the minute parts of a body. If this be the case, and if it be correct: that contact of itself cannot liberate free electri-’ city, we may conclude that the developement of electricity cannot take place unless some kind of action give rise to it.” ‘“‘ Can the electro-chemical theory, in which it is set forth that the affinities by virtue of which bodies strive to unite, are nothing else than the result of their opposite electrical state? Can this theory be reconciled with the experiments above de- Chemical and Physical Science. If tailed, especially with the fact, that a body may be positive in respect of one body and negative in respect of another ?” “ This theory seems to me to depend chiefly upon two facts ; namely, the one, that bodies have a particular electricity which contact developes,—a fact, the erroneous nature of which I have endeavoured to show; the other, that in every decomposition caused by the electric pile, some bodies, those called negative, go to the + pole, others, those called positive, to the — pole ; but I have in the foregoing treatise shown that it is not in vir- tue of electric tension, or as a consequence of common electric attractions and repulsions, that the decomposition takes place, since it goes on the easier the greater the conducting power of the liquid,* and the less consequently the tension. It seems to me, then, that, as we cannot admit the two facts above named, the electro-chemical theory, which depends upon them, has no sure foundation.” | Berzelius’s remarks on these observations are as follows :— * De la Rive seems to be persuaded that the result of his experiments overturns the application of electrical views in che- mistry. I do not partake in his persuasion,—on the contrary, I think his experiments give a new confirmation to it. At the same time, all depends upon the point of view from which we set out. De la Rive treats separately of contact, chemical action, and the developement of electricity, as altogether inde- pendent of each other; and he has in one place said that che- mical processes excite electricity like friction, &c. If it be right in scientific philosophy to consider these as independent, then may De la Rive’s result be opposed in some measure to the electro-chemical theory. But if, on the other hand, it is right to admit, that, upon every occasion of contact between bodies, * Ritchie’s first experiment in the paper above referred to is in no way in- consistent with this. Sulphuric acid in that case did not conduct any elec- tricity, because, there being no chemical action, there could, according to the chemical theory, be no developement. In regard to conductors, De la Rive has shown also,—I1st, That different liquids transmit electricity to solid bodies with different degrees of facility ; 2d, That of two metallic sur- faces similar or dissimilar, that which most easily gives out its electricity ~ to a liquid is positive in respect of the other in the same liquid ; and, 3d, That a metal or a liquid may be a good conductor for one intensity and a bad one for another. * 12 Berzelius’s yearly statement of the progress of an affinity (foreningsbegir, desire of union,) belonging to mat- ter begins to manifest itself,—if this affinity coincides with elec~ tric energy in such a way, that where the one shows itself the other is manifested to such a degree, that the electro-chemicak theory sets them down as identical, (and this mode of consi- dering the phenomena in connection is probably the right one,) then De la Rive’s experiments contain nothing in oppo- sition to its views. All the inversions of contact electricity which De la Rive has brought forward in his first treatise, and which he so skilfully contrived for bringing out the resilt he wished to arrive at, cease to be exceptions, when we remember that liquids give electricity of contact with one another as well as with solid bodies, and that this may be much stronger * than that between two solid bodies:—and when we remember that in the cases brought forward by De la Rive, the metals whose polarity changed in respect of each other, lie very near’ in the electrical series; + and thus their electricity is easily de- stroyed by a change produced by the action of the liquids upon each other or upon one or both the metals. If the elee- tro-chemical theory be well founded, no electricity of contact can ‘be developed in a hydro-electric combination, nor any electric stream arise unless a chemical action take place. De la Rive has shown that such is the case, and yet he has drawn from it the very opposite result, that it is opposed to the spirit of these theoretical views. So differently may facts be judged: according to the point of view from which they are regarded. In general, it is proper to:remember that those who would: overthrow the electro-chemical theory, must not stop at those phenomena of contact electricity, in which unknown circum. stances, with their inexplicable bizarreries often mock our ef- forts; but they must persuade us that the electrical state which De la Rive calls, etat de courant, does not overcome and de- stroy the strongest chemical affinities,—does not present them to us in am order quite the opposite of that in which they are previous to the action of the stream,—does not, for example, * This is exactly what we have urged above more in detail ; in our re- marks upon Mr Ritehie’s 3d experiment. . 4+ This argument is still stronger against.a change of polarity in ti case of two plates of the same metal. ee eee Chemical and Physical Science. 1S in the same liquid unite gold with chlorine, and reduce ‘iron when the former is positive and the latter negative; and till this is done we cannot consider electrical energy and chemical affinity as two separate and independent principles.” Heat.—Passing on to the subject of heat, we have an account of some researches of Svanberg into the heat of the planetary space. It is known that Fourier, in his valuable researches into this subject, deduced from the laws of radiant heat that the tem- perature of the planetary space is — 50° Cent. = 58 Fahr., and that the earth has nearly reached its limit of cooling. Svanberg has built his researches upon a different principle, and has ob- tained the same result.. From his letter to Berzelius on the sub- ject, we extract the following :—* Led by these considerations, and by the many known affinities between light and heat, which are especially remarkable in the acknowledged property of solar light to develope heat in opaque and imperfectly transparent bodies, I began by supposing that the planetary space (consider- ed as perfectly pellucid) never undergoes any change of tempe- rature either from the action of light or of radiant caloric, and that, therefore, the capacity for elevation of temperature above what reigns in the ethereal regions, can exist only within the limits of the planetary atmosphere. Further, that the rapidity of the change of temperature at an indefinite height above the surface of the earth, is always proportional to the rapidity of the atmosphere’s corresponding change of capacity to absorb light. In this way I obtained the temperature of the atmos- phere, (expressed in a function of an indefinite height above the earth’s surface) containing only two arbitrary constants, of which the one is also a function of the time, and is determined always by immediate observation of the given temperature at the mo- ment on the earth’s surface; the other, namely the tempera- ture of the planetary space, is constant, even in regard to the ume. : ‘* The numerical solution presupposes accurate observations of temperature at isolated points to a considerable height above the earth’s surface, which, however, are unfortunately so ex- tremely few, that we can have recourse among newer observa- tions to but a single one, that of Gay-Lussac, in his aeronau- tic expedition. It were to be wished that the same: experi- ca 14 Berzelius’s yearly statement of the progress of ments were repeated particularly in the neighbourhood. of the equator, where the oscillations around the mean state of the atmosphere, and consequently the prejudicial influence of .ac- cidental circumstances are less to be dreaded. In the mean- time, availing myself of this observation, [ have obtained for the planetary space a temperature of — 49.85 Cent. which dif- fers only by + of a degree from the result of Fourier, deduced from the laws of heat radiated from the mass of the earth, the temperature of which he supposed,to have reached its asymptotic state of absolute unchangeableness on the whole. Without believing im the identity of light and heat, or in the certainty of our photometric knowledge, I have thought it not entirely void of interest to see what result, in relation to this point, could be obtained from Lambert’s statements, in regard to the absorption which takes place in a ray of light passing from the zenith through the whole. atmosphere, calculated on the supposition that the differential of the increase of tempera- ture is always proportional to that of the so absorbed. light. By this process I have obtained for the required temperature — 50°35. I was most agreeably surprised by so remarkable an agreement between both of these results and that which Fourier derived from principles so different; and it affords an addi- tional reason why the function I have given for the tempera- ture should be taken into due consideration. The immediate results of the same are, that the temperature diminishes with a constantly diminishing velocity, as we ascend in the atmosphere, and that even at a given height, this velocity is greater, the higher the temperature at the earth’s surface. *¢ Without having in view any examination of the fami for determining heights by the barometer, I have, in the ap- plication of them to the observations of Guy-Lussac, shown, that in the determination of heights so uncommon as that of Gay- Lussac, causes of error may intervene, which in the case of lower and more common heights it is not necessary to take into account. To me that function is of importance, since from. it I have derived a function for the refracting power of the atmosphere at all points of the trajectory of light, and I have, by way of preliminary, treated in considerable detail the formule derived from it, for the definitive determination of the refraction it- self, in which I have proceeded so far that I have at last com- Chemical and. Physical Science. 15 menced the purely mathematical investigation of the required problem, such as it becomes after the strictest discussion of all the physical points connected with it.” | Inorganic Chemistry.—Of the more important matters under — this head, we shall give a brief catalogue Raisonnée. . Phosphurretied hydrogen.—Rose has shown in regard to this gas, that it throws down only those metals which phos- phorus alone precipitates,—that both the hydrogen and phos- phorus are oxidized at the expence of the metallic oxide,—and that the precipitates are always, except in the case of mercury, which comports itself in a peculiar manner, in the metallic state.* Hydrate of Bromine——Lowig has found that bromine combines with water at the freezing point, forming beautiful red octohedral crystals, which are decomposed by a heat.of 54° Fahr. It may also be formed by passing gaseous bro- mine through a moist tube at a temperature of 30° or 40° Fahr. + | Iodide of Azote-—To prepare this compound, Mitscherlich dissolves iodine in aqua regia, and obtains chloride of iodine. This chloride saturated with ammonia gives chloride of am- monium and iodide of azote, which, if the quantity of iodine employed do not exceed a grain, may be safely collected on a small filter. + 3 .. Lodides of Carbon.—According to the analysis of Serullas, the solid iodide consists of | carbon + 3 iodine = C I*, and the liquid iodide of 1 carbon + 2 iodine = C I2.§ Hydriodic Acid—Felix d’Arcet evaporates hypopbospho- rous acid till it begins to give off phosphuretted hydrogen,—he then mixes it with an equal weight of iodine, and applies a . gentle heat. ‘The phosphorus is acidified at the expence of the water, and the hydriodic acid comes over with such rapidity that it may be collected over mereury, and when the flask is full, be removed and corked without undergoing decomposi- tion. || * Poggendorf’s Annals, xiv. 183. _+ Ibid. p. 114. + Ibid. p. 539. § Ann. de Chim. et de Ph, xxxix. p. 230. j, Ibid. xxxvii. 220. 16 Berzelius’s yearly statement of the progress of Chlorides of Cyanogen.—W hen cyanide of mercury with a little water is exposed to the sun’s rays in an atmosphere of chlorine, an oily compound is formed, which collects on the bot- tom of the vessel. By the panetbente of Serullas this is : a sesqui-chloride of cyanogen — cy.? chl.° 2°. If 20 grains of anhydrous hydrocyanic acid be ms to i sun’s rays in a flask containing 80 or 100 cubic inches of chlorine, at first a liquid and afterwards a solid partly crystals lized white substance is deposited on the inside of the glass; After a few days the flask is opened, the muriatic acid blown out, and the white substance detached by a little water and fragments of glass. It is pressed, dried perfectly, and distilled. A colourless liquid passes over, which solidifies into a crystalline mass. This is bichloride of cyanogen, > cy. chl.? and consists of 73.46 chlorine + 26.54 cyanogen, or 1 vol. cyan. + 2 vol. chlorine. It is white, crystallizes in needles, has a powerful odour, causing tears, and a weak pun- gent taste, reminding one of the smell. _ It has a specific gra-_ vity of 1.32, melts at 284° Fahr. and boils at 374°. It is sparingly soluble in cold, but more easily in warm water, which decomposes it, forming muriatic and cyanic acids. The cyanic acid is different from Wobhler’s. It dissolves with ease in alcohol and ether, and the aléoholic solution is precipitated by water. It is very poisonous. Cyanic and Cyanous Acids.—If the bichloride Ist mention- ed be treated with water till completely dissolved, then evapo rated slowly to dryness, and the solid substance which re- mains purified by one or two recrystallizations, we obtain a . pure colourless acid in small transparent rhombs, of a specific gravity between 1.7 and 1.8. According to Serullas, it con- sists of 61.89 cyanogen + 38.11 oxygen, or 1 atom cyan. + 2 atoms oxygen. The acid of Wohler has only half the oxy-~ gen, and must therefore be called the cyanous acid. > sane composition is (Serullas) Cyanic Acid, 1 atom cyan. + 2 atoms oxygen: ” (Wohler’s) Cyanous Acid, 1 cyan. + 1 oxygen. The cyanic acid sublimes in needles, undergoing also a par- tial decomposition by the heat. It dissolves with difficulty in water, and has therefore no particular taste. It reddens lit- Chemical and Physical Science. 17 _taus paper, dissolves’ without change in sulphuric acid, and imay be thrown down by water. - It is dissolved by: boiling nitric acid, and separates from it by crystallization. The nitric acid may be distilled from it without producing decomposition. It does not seem to be poisonous. With potash, it gives a neuttal salt, which is'easily soluble, and an acid salt, which ah solves with difficulty. _ Sulphuret of Cyanogen.—Lassaigne,* by mixing Serehiloride of sulphur with twice its weight of cyanide of mercury, and leaving them some days ina flask, has obtained a colourless crystalline sublimate, which is a new compound of sulphur and cyanogen, having the following properties: It sublimes spon- taneously into rhomboidal scales, which powerfully decompose light... It is very volatile, has a pungent odour, and seems to act with considerable energy on the animal economy. © Ex- posed to air and light, it soon becomes yellow. It dissolves both in water and alcohol. Its solution in water reddens lit- mus, and gives a red colour to the salts of iron. This is the only compound of these two elements which has hitherto been obtained in an isolated state. It contains 24 per cent. of sul- phur, and may therefore be considered as a di-sulphuret of cy- anogen ; we have therefore three known Oe of sulphur and cyanogen, 1° Latom sulphur + 2 atoms cyanogen oe sulphur + 1 cyanogen 3° 4 sulphur + 1 cyanogen The first is the sulphuret of cyanogen of Lassaigne. The second the base of the Gist ph sie fasts acid of Porret. - The third is the base of the sulphuretted sulpho-cyanic acid _ of Berzelius, a yellow compound obtained by heating sulphur in prussic acid vapour. Magnesium. —Bussy + has obtained this metal in the form of a brown metallic powder, not oxidizing by contaet with air, water, or dilute nitric acid, but dissolving in caustic potash and muriatic acid, and at a high temperature. burning with residue of magnesia. He prepares it by passing ryan in vapour over dry chloride of magnesium. * Poggendorf’s Annals, xiv. 532. + Journal de Chim. Medicale, iv. 456. NEW SERIES, VOL. III. No. 1. JULY 1830. B > 18 Berzelius’s yearly statement of the progress of We subjoin the following remarks of Berzelius suggested by the name of this metal: ‘ The radicals of magnesia and manganese have their name from the same word. The one is called magnesia alba, and the other magnesia nigra. When the metal of the latter was obtained it was immediately distin- guished by the name Manganesium. Philologists found this word too long, as well as badly derived, and Buttmann chose the name Manganium, from the common root of both, wuyyavoy, which was adopted by Klaproth, and followed in the Swedish, German, and Danish nomenclatures. In England they retain the word manganesium. ‘To prevent confusion, Davy adopted for the radical of magnesia the name magnium. This may be good enough in the English nomenclature, in which they. are not scrupulous about regular derivations, but when dis- tinguished German authors use both magnium and man- ganium, it is to introduce changes without reason, and to destroy the simple uniformity of name, which might be at- tained by the general use of the term manganium.” This complaint of Berzelius is not without good ground. In this country we can hardly mistake between the generally receiv- ed terms magnesium and manganese ; but when in Germany we find magnium, magnesium, and talcium, as synomyms for the former, and mangan, manganium, and magnesium for the latter, there is at least a confusion in sound which is per- plexing in a chemical nomenclature. Glucinum and Yttrium.—We have not space for more than a notice of the reduction of these two metals by the indefatiga- ble Wohler. He obtains them from the anhydrous chlorides by means of potassium, in a way analogous to that in which he formerly reduced aluminium. They are procured in the form of dark grey powders, not oxidized by air or water, but burning when heated, and leaving glucina and Yttria respec- tively. Their compounds are described in Poggendorf’s An- nals, xiii. pp. 577 and 581. Reduction of sulphuret of Arsenic.—Liebeg has perfected the detection of sulphuret of arsenic. He draws out a fine tube, as for the reduction of arsenious acid by charcoal, drops into it a minute fragment of the sulphuret, and covers it two or three lines deep with carbonized acetate of lime. Imme- Chemical and Physical Science. 19 diately on heating, the arsenic is deposited in the metallic state on the upper portion of the tube. Iodide of Arsenic.—Plisson has shown that the pt way of preparing this compound is to digest three parts of metallic. arsenic in fine powder, with 10 of iodine, and 100 water. When it ceases to smell of iodine it is evaporated, and the compound shoots out into red crystals consisting of 1 atom arsenic, 3 atoms iodine. New Chromic Acid.—This green acid, described by Koech- lin in the Bulletin de Sciences Mathem. &c. February 1828, p- 132, is shown by Berzelius to be a bitartrate, which, like many other tartrates, is not precipitated by alkalies, but gives with them crystallized double salts. Metals.—In a former Number of this Journal we gave the results of several analysis of platina ores by Berzelius. The very elaborate paper in the T'ransactions of the Swedish Aca- demy for 1828, from which. these were taken, contains many valuable researches into the nature and combinations of the metals which accompany platinum. As'these, we believe, have not appeared in any English Journal, we shall here present a short view of his results, Atomic Weights.—These weights, determined from the de- composition of the double Salts, differ considerably from his former numbers, and are as follows: Platina and iridium, 1233.427 Osmium, — - 1244. 22 Rhodium, 651. 38 Palladium, = —- 665.784* Oxides.—Iridium has four oxides. The protoxide = 1 iridium + 1 oxygen. Sesqui-oxide = 2 +3 Deutoxide =] +2 Tritoxide ae +3 ? » These atomic weights, as formerly given by Dr Thomson, are rho- dium 5.5, iridium 8.75, palladium 7. : " ° i : 20 Berzelius’s yearly statement of the progress of The first, second, and fourth can be obtained in a separate state; the third exists only in the form of salts. |The se- — cond is the most fixed. It bears a red heat without decom- position, but is decomposed by hydrogen gas at common tem- peratures. The blue oxide is a combination of the proto and sesqui-oxides, as the blue oxides of Molybdenum and Tungsten are combinations of two degrees of oxidation. — | Osmium has a specific gravity of about ten, and forms five oxides,— Protoxide — 1 osmium + 1 oxygen. Sesqui-oxide = 2 +3 Deutoxide. = 1 +2 x Tritoxide = 1 +3 Osmic acid — | + 4 These oxides. may be obtained in a permanent form from the corresponding chlorides. The acid alone is volatile, and in close vessels the other oxides are not reduced’ by heat into the volatile acid and metallic osmium, as might have been ex- ‘pected. In open vessels they absorb oxygen, and are driven off. Osmium gives a blue oxide, a combination of the two low- est, which is obtained when a solution of the acid is mixed with sulphurous acid, and left for some time in a corked flask. ‘The ‘solution has exactly the appearance of a sulphate of indigo. Rhodium has two oxides,— ° Protoxide = 1 rhodium + 1 oxygen. Tritoxide — 1 + 3 These combine in various proportions, but no distinct deut- oxide has been obtained. Palladium has two oxides,— Protoxide = 1 palladium + 1 oxygen. Deutoxide = 1 ————— 2 The second of these is new, as is the bichloride to be after- _wards mentioned, and is obtained from the double salt of po- tash and bichloride, by digestion with caustic or carbonated alkalies. It is of.a brown colour ; dissolves slowly in oxygen acids, giving a golden yellow solution... From dilute «muriatic 4 : Chemical and Physical Science... Q1 acid it developes ShlOsine: but: with concentrated forms bi- chloride. Carburets.—Carbon “ie iridium combine with great ease, forming a quadri-carburet of iridium. Sulphurets of iridium are obtained on aisinvomagin his chlorides by sulphuretted hydrogen. They dissolve with ease. in nitric acid, forming sulpho-salts. By a red heat they are changed into subsulphates. Osmium has as many sulphurets as oxides, which may be formed either by the humid or the dry way. Those with less sulphur obtained by precipitation are yellow and partly solu- ble in water; that with most is thrown down completely from an acid solution. Heated in vacuo it gives off sulphur, and changes with combustion (eldphenomen) into a compound of two degrees of sulphurization, which contains two atoms metal with five of sulphur, and is qecdeipancd with great difficulty by heating in hydrogen gas. _ Phosphurets.—Iridium and osmium combine also with phos- phorus. The sulphuret of iridium is gray, that of osmium re- sembles the metal, but is not volatile; leaving when heated a subphosphate of osmium. i Salts.—We have not space to give even an analysis of the interesting matter Berzelius has brought together in regard to the saline combinations of these metals. We shall merely in- sert, therefore, a view of the composition of the double salts. Iridium unites with chlorine in four proportions, forming a chloride, a sesqui-chloride, a bichloride, and a terchloride, an- alogous to the oxides... Berzelius.has. formed and, analyzed a series of double salts constituted as follows :— 1 atom chloride of potassium +) 1 atom chloride of iridium. 1 : ammonium + | 1 potassium + 1 —— sesqui chloride of 1 . + 1—— bichloride 1 —— of ammonium + 1 1 ———— of sodium +1 of iridium + 6 water. d potassium + 1 terchloride of iridium. The fourth of these is the common double salt formerly known. Osmium combines with chlorine in the same proportions as 22 Berzelius’s yearly statement of the progress of iridium, and forms double salts of the same appearance and composition as those above-mentioned. ‘Those containing po- tash Berzelius has formed and described. The red double salts of rhodium, with potassium and soditim, are unlike in composition. ‘They aré coniposed of 3 chloride of sodium — + 1 terchloride of rhodium + 18 water. 2 - potassium + 1 - + 1 Of palladium Berzelius has formed two new double salts, consisting of 1 atom chloride of potassium + 1 bichloride of palladium. 1 —— ammonia + 1 chloride — The latter singular compound is obtained by treating chlo. ride of palladium with caustic ammonia, and evaporating. From these results it will be seen how much Berzelius has done for this hitherto obscure portion of chemical science, by his examination of these rare metals. The liberality of the Russian government put it in his power to prepare them in large quantities, and to subject them to repeated investiga- tions. It was not without considerable pleasure that we saw in his laboratory a whole phial filled with metallic osmium, and not without still more that we were presented with a portion of it for our own use. But the quantity of the ore found in Russia, and the employment of platinum in coinage, will soon make the associated metals more plentiful. Fulminating Silver.—Mitscherlich’s mode of preparing this substance is very simple. He dissolves a silver salt in catistic ammonia to saturation, and adds caustic potash in excess. The fulminating silver falls immediately, and more is obtained by: heating till the ammonia is driven off.* Red Lead.—This ‘substance is generally supposed to be a mixture of protoxide and peroxide of lead in variable propor- tions. ** In some very beautiful red lead,” says Dr Thomson, “I have found the proportion of protoxide amount to nearly one- half of the whole weight. Acetic acid dissolves out the protoxide, and leaves the peroxide untouched.” + Fischer has shown that red lead dissolves in concentrated acetic acid, giving a clear ~ ” Poggend. Ann. xii. p. 143. + First Princtples,fi. 397. | Chemical and Physical Science. 23 colourless solution, which in a close vessel undergoes no change. Water decomposes it, and throws down the brown * oxide. “« I have repeated this experiment,” says Berzelius, “‘ and find that a small quantity of acid converts the minium into a co- lourless salt ; a larger quantity dissolves it. Heat throws down the brown oxide without previous dilution. This seems to show that red lead is not, as some have supposed, a compound of two oxides.” If so, it will be the sesqui-oxide of lead. _ Sulphurets of Lead.—Bredberg,t in a paper which has been thought worthy of one of the annual prizes of the Swedish Academy, has shown that lead has two lower degrees of sul- phurization than those formerly known, One of these is ob- tained when twenty-five parts of sulphuret of lead (atom to atom,) are mixed with 21.6 of lead in fine grains, and melted for fifteen minutes under glass of borax. Its fracture is cry- stalline and scaly, and it is so soft, that it can be beat out under the hammer without breaking. It is a di-sulphuret of | lead. The other is obtained by melting the same mixture in the open air without glass of borax. Its fracture is fine-grain- ed; it is still more malleable than the former, and is also sec- tile. It contains only half the sulphur of the former. He has shown also, that the mixed ores known in Germany by the names of stein, bleistein, kupferrohstein, dunnstein, &c. con- tain the proto-sulphuret of iron combined in exact chemical proportions with the former of these, the di-sulphuret, with the di-sulphuret of copper, and, occasionally a proportion of zinc. The known sulphurets of lead therefore are,— The protosulphuret = 1 atom sulphur + 1 atom lead, the common galena. Di-sulphuret at 9 - +2—— Tetrasulphuret =i +4 Bredberg is a young Swedish chemist of considerable pro- mise, and one of the Professors in the School of Mines at Fahlun. Isomorphism.—Mitscherlich, + who has done so much to this very interesting department of crystallography, has shown that ~ * Jahrbuch fur Ch. und Ph. ti. p. 124. + R. Vet. Acad. Hand. 1828, p. 126. + Poggendorff’s Annals, xii. p. 137. _ 24 Berzelius’s yearly statement of the progress of the sulphuric, selenics and chromic acids are isomorphous, giv-' ing salts of the same form where the bases and the quantity water is the same. ' » Hypophosphites.—Rose * has investigated sas salts. and their acid. His mode of preparing them is, with some slight differences, the same as that of Dulong, the discoverer. He describes them, like Dulong, to be all soluble in water. Most of them also crystallize. Of the alkaline salts that of soda crystallizes ; those of potash and ammonia -are deliquescent ; those of barytes, strontian, and lime, crystallize, giving flexi- ble crystals. They contain three atoms water to two of salt. That of barytes dried in the vacuum of an air-pump contains three atoms water to one of salt. The salt of magne- sia crystallizes in regular octohaedrons, and contains eight) atoms water. The cobalt salt forms large red: regular octo- haedrons, containing eight atoms water. The salt of nickel is isomorphous with the last two, and contains the same quantity of water, but does not crystallize so readily. That of lead differs from the rest in being insoluble in alcohol, and but sparingly in water, from which alcohol throws it down. | The neutral salt forms crystalline plates. ‘The acid forms also dou- ble salts. That of cobalt and lime gives red octahaedrons, containing three atoms water. They are merely a joint cry- stallization of the isomorphous salts, with a difference in the quantity of water. The acid is composed of re 2 atoms phosphorus +. 1 atom oxygen. With protoxides it unites atom to atom. With tritoxides it forms sesqué salts. | ‘if Alwm.—Kralowanszky has formed a lithia alum, having pre- cisely the same composition as those already known. Fischer has also discovered a chrome alum, in which the green oxide of chrome takes the place of the alumina in the other alums. Their composition will be mey seen from the following for- mulse :— LS + AlS* + 24 water. Lithia alan, PS 4+CrS8é+ 24+ Chrome alum. “ Poggendorff’s Annals, xii. 411, + Dr Thomson assigns 25 atoms water to all ae alums.— First Prin- ciples, ii. p, 440, Chemical and Physical Seience. 1 It appears, therefore, that lithia is isomorphous with the other alkalies, and the tritoxide of chrome with alumina, which is also a tritoxide. Hence chromium and aluminum are: pro- bably isomorphous also. Bromides——The bromides of arsenic, antimony, and bis- muth, consist, according to the experiments of Serullas,* of one atom bromine + three atoms metal. Carbonate and Acetate of Copper. iit Leber has shown that the black powder obtained from the carbonate, and the brown from the acetate, by boiling in water, are only oxide of copper. Berzelius had some years ago shown this in regard to the acetate. | Chemical Analysis.—Under this head we shall mention two particulars. A mixture of five parts carbonate of potash, and four car- bonate of soda, melt easier than either separately. Mitscher- lich + has applied this to the decomposition of mineral sub- stances, which takes place with such ease in this mixture, that as much as 220 grains may be melted over the flame of a lamp. Sand thrown into it in small portions dissolves imme- diately with evaporation, exactly as when an acid is poured upon an alkali. It has hitherto been a very difficult matter to determine the amount of boracic acid in mineral bodies. Dumenil dissolves the mineral in nitric acid, separates the silica by. evaporation, and, with the neutral solution, mixes nitrate of silver in excess, and evaporates todryness. On re-solution the borate of silver remains, being a di-sesqui-borate, consisting of two atoms acid + three oxide of silver. As the borate dissolves in free nitric acid, it may in this way be separated from chloride of silver. § Mineralogy.—Of the new minerals described, and analysis given by Berzelius, several have already appeared in this Journal. We shall notice those only which have not previous- ly been laid before our readers. “ Annal. de Chim. xxxviii. 318. + An. de Chim. xxxvii. 385. t Pog. An. xiv. 189. § Jahrbuch fur Chim- und Phys. 182, i. 364. 26 Berzelius’s yearly statement of the progress of Seleniurets—Del Rio has analyzed a grayish black crystal- lized mineral occurring with native quicksilver in limestone, which lies on red sandstone in the mining district E] Doctor- Culebras, Mexico. It consists of Selenium 49, zine 24, mercury 19, sulphur 1.5; which Ber- zelius calculates to be 4 zine, 1 mercury, and 7 selenium, from which he deduces the formula, 2 Zn? Se +H g Se; or it is a compound of 2 atoms sesqui-seleniuret of zinc + 1 seleniuret of mercury. Kersten has examined another Mexican mineral occurring with mercury and sulphur in quartz and calespar, and has found it to be a mixture of sulphuret and seleniuret of mercury. The mineral which Tiemann found in the Hartz, and, from its being entirely volatile, judged to be native selenium, Marx has shown to be also a seleniuret of mercury. Silver Phyllinglans.—Under this name Breethaupt has de- scribed a mineral occurring with galena at Bérsén in Hun- gary, in gneiss. It is dark lead-gray, and consists of thin flexi- ble scales of a specific gravity = 5.895, and metallic lustre. It is a compound of seleniurets of silver and molybdenum. Couzeranite.—This mineral occurs in the overlying chalk around Couzeran in the Pyrenees. It is in the form of ob- lique rhomboidal prisms, longitudinally striated ; cross frac- ture uneven ; longitudinal, scaly; conchoidal. Colour black ; lustre glassy. Scratches glass, but not quartz. _ Specific gra- vity = 2.69. Melts before the blowpipe, but does not dis- solve in acids. Dufrenoy * has found it to consist of silica 52.85, alumina 24.25, lime 12.04, magnesia 1.46, potash 5.63, soda 8.75. Dufrenoy deduces from this, that the mineral consists . of one atom of the bisilicates of potash and soda + two of the tersilicates of lime and magnesia + six silicate of alumina ; but as it is rare to find the alkalies and alkaline earths oomiiaa with unequal atoms of silica, Berzelius prefers the following formula :— Lime ni, Magnesia is + ie 1 atom tersilicate. Bisast, + 2 silicate of alumina. Soda * Ann. de Chim. et de Ph. xxxviii. 280. \ Chemical and Physical Science. of 27 Pectolite occurs in the Tyrol with mesotype and mesolite, the latter of which it resembles so much, that it can with difficulty be distinguished from it without the help of analysis. It has a vitreous lustre externally, but pearly within. Specific gra- vity = 2.69. Kobell found it to consist of silica 51.3, lime 33.77, soda 8.26, potash 1.57, water 3.89, alumina, with a lit- tle oxide of iron, 0.9. It is composed, therefore, of 1 atom tersilicates. ae + 4 bisilicate of lime + 1 water. Berzelius remarks, that before the blowpipe he found it give a strong reaction of fluoric acid, from which he infers, that the 0.9 given as alumina, was, as in the apophyllite, fluor spar dis- solved and precipitated. Okenite, a new mineral from Disk Island, Waygat’s Straits, belonging to the zeolite family. It occurs in amygdaloid.g Is white, fibrous, or finely radiated. Hardness between fluor and feldspar. Specific gravity — 2.28. Melts before the blowpipe with intumescence. Is decomposed by acids, and becomes ge- latinous. According to Kobell, it consists of silica 56.99, lime 26.35, water 16.65; which agrees with 1 quadrisilicate of lime + 2 water, or perhaps more properly : 1 hydrated tersilicate of alumina + 1 hydrate of silica, as quadrisilicates are quite uncommon. Karphosiderite.—Breithaupt has given this name to a mine- ral from Greenland, uncrystallized, kidney-shaped, earthy, and tust coloured. From its action before the blowpipe, Harkort states it to be a hydrated subphosphate of iron. Tautolite—This mineral occurs in lava around Leacher: dee. It isblack ; full of cracks ; sometimes in small crystals ; gives a gray streak ; has a dull glassy lustre; is friable, and has a specific gravity of 3.865. Harkort examined it by the blowpipe, and considers it to be a proto-silicate of iron with silicate of alumina, but decidedly different from olivin. Fergusonite, from Cape Farewell in Greenland, has been analyzed by Hartwell, who found it composed of tantalic acid 47.75; yttria 41.91; protoxide of cerium 4.68; zirconia 3.02; oxide of tin 1.0; oxide of uranium 0.95; oxide of iron 1.34; loss 0.35. He has classed it with the yttrotantalite, with which it agrees in composition, except that the bases in the _ y 28 Berzelius’s yearly statement of the progress of Fergusonite take up twice as much tantalic acid as in the yttro- tantalite, and that here the oxide of cerium and ziréonia take the ore of the lime. Its formula is: Y3 Qi or a tritantalate of yttria and cerium mixed with tantalate of zirconia. Aeschynit, brought from Mias in Ural by Menge, and analyzed by Hartwell, gave titanic acid 56; zirconia 20; per- oxide of cerium 15; lime 3.8; oxide of iron 2.6; oxide of tin 0.5. Hartwell does not give this as perfectly correct, because we are at present unacquainted with any method of separating correctly the titanic acid from the zirconia. From this cir- cumstance Berzelius has given it the name Aeschynite from cusyuvw, I am ashamed. Phosphate of Copper.—Kobell has- ehowsi that the cuivre hydraté globuliforme of Haiiy is a phosphate of copper, and Bergman has shown it to be identical with that from Rhein- breitbach, analyzed by Arfvedson, whose composition is, st T a mixed with Zr Ta 2Cu P+ 5 water. Dioptase.—A specimen of perfectly pure dioptase, analysed by Heess, has been found to contain oxide of copper 48.89 ; protoxide of iron 2.0; silica 36.6; water 12.29; and gives . the formula Cu? Si? + 3 water. It is therefore a di-sesqui- silicate of copper with three atoms of water. This differs con- siderably from Vauquelin’s result, which, however, was obtain- ed from an uncrystallized specimen—a silicated malachite. White iron Sinter.—Kersten has analyzed an earthy white or grayish yellow mineral, found in reniform masses in the old mines at Fiirstenstoll at Freyberg, and found it to consist of arsenic acid 30.25; peroxide of iron 40.45; water 28.5. It is therefore a di-arseinate of iron with 12 atoms of water. Datholite—Two new analysis of this mineral have been made by Stromeyer and Dumenil. We shall contrast them with the previous analysis of Klaproth. Stromeyer’s was from Andreasberg—Klaproth’s from Arendahl. Chemical and Physical Science... 29 Klaproth. . Dumenil. Stromeyer. Calculation. Silica, 36.5 38.51 37.36 37.51 Lime, 35.5 35.59 35.67 38.61 Boracic acid, 24. 21.34 19.37 18.91 Water, 4.00 4.6 5.71 49 The calculation supposes it to be a di-borate of lime + 3 ter- silicate of lime + 2 water. Diallage:-—W e cannot withhold from our readers the results of Kohler’s elaborate examination of this substance, and the philosophical deductions from them as to the composition of a great variety of mineral substances. : M = : = . = £ = ne cf, g22 28 B42, €2, $5 o g te. =e, 3a 23 22% 252 of $23 SBS SEE asm 383.-. 386 ba" 88° €3 AS AB Aas Ss fa aD Silica, 53.707 51.388 53.200 53.739 57.193 56.813 Magnesia, 17.552 15.692. 14.909 25.093 «32.669 29.677 Lime, 17.065 18.284 19.088 4.729. 1.299 | 2:195 Protoxide of Hee f 3.671 11.510 7.461 8.464 ~ Magnesia, f %°79 92304 O.360 0.933 0.349 0.616 Alumina, 2.825 4.388 2.470 1.335 0.698 2.068 Water, 1.040 2.107 1.773 3.758 0.631 0.217 When we compare these results, says Berzelius, with those of Henric Rose concerning the pyroxenes, we find a striking re- semblance between them, which leads to the conclusion drawn by Kohler, that they contain the same kinds of combinations, namely, bisilicates of the isomorphous bases, lime, magnesia, and protoxides of iron and manganese—and that the alumina supplies the place of a deficient quantity of silica, as is the case with pyroxene and amphibole. To the similarity of composi- tion, Kohler has added the resemblance in the angles of the crystals; which can be shown to exist in several species. If we endeavour to find in the composition a cause for the differen- ces in cleavage and outward appearance between diallage and pyroxene, we shall discover it by a comparison of the analysis of both classes of minerals. In the pyroxenes, the silicate of : : 80 Berzelius’s yearly statement of the progress of lime is seldom represented by any other bases. They are bisili- cates of lime combined with mixed silicates of magnesia, pro- toxide of iron and manganese. In the diallage, the silicate of magnesia predominates, from the bronzite, which seems to be a mixed crystallization of bisilicate of magnesia with small quan- tities of the others to diallage, which is shown to be a double bisilicate of magnesia with compensating portions of bisilicates of lime, iron, and manganese, mixtures which have their ori- gin plainly in mere chance. Neglecting the mixed alumina, therefore, we may represent these relations by the following formula : M C Ryrosege CS?+F } S? diallage M S? 4 F ks Mn M » 'M And hypersthene or bronzite p82 Mn There seems to us to be three points necessary to a philoso- phical comprehension of the nature and mode of formation of the vast diversity of mineral substances. These are, chemical analysis, the atomic theory, and the doctrine of isomorphous bodies. Rightly applied, their aid will unlock all the mystery which variations in external characters throws around the study of mineralogy. Analysis setting before us one true atomic compound, will class along with it hundreds of others which vary only in the nature of the impurity with which they are contaminated—while the principle of isomorphism will enable us to predicate what those impurities must be. Ex- cept, indeed, as the handmaid of the more exact sciences, of chemistry, crystallography, or optics, the study of minerals is not in itself a science. All their combinations are aeciden- tal. ‘They are formed by the union of bodies uniting, indeed, according to fixed and natural laws, but brought within the range of their mutual affinities by chance ; for we cannot con- ceive it to have been intended for any wise purpose that a mineral should be found pure in one place and impure. in another. ‘The mere study of minerals, therefore, as such, is a Chemical and Physical Science. 31 inferior to any other branch of natural history, for the mean- est plant or animal that grows or moves has a principle of life in it which lifts it out from the mass of inanimate nature, and imparts a dignity to the study of its organization which many even of the recondite investigations of chemistry are far from possessing. — Epidote Manganesifere from St Marcel, has been clas- sed by some mineralogists among amphiboles. Cordier’s ana- lysis was not satisfactory. Hartwell finds it to consist of sili- ca 38.47; alumina 17.65; lime 21.65; peroxide of manga- nese 14.08; of iron 6.6; magnesia 1.82. This result shows that the crystalline form had rightly indicated the composition of an epidote, since the lime is here exactly compensated by a small quantity of magnesia, and the alumina by the isomor- phous oxides of iron and manganese, of which the latter has, for the first time, been made out with certainty as ‘one of the elements of a double silicate, and is indeed the colouring mat- ter in this mineral. Hartwell gives the following formula, a A u}S+2 Mats Steatoid—The crystallized mineral from Snarum in Nor- way, described by Moller under this name, has been analyzed by Hartwell, and found to be identical with noble serpentine. It consists of silica 42.97; magnesia 41.66; peroxide of iron 2.48 ; alumina 0.87; water and carbonic acid 12.02. Vegetable Chemistry. —Animal and vegetable chemistry af- ford to the man of science the most astonishing field of con- templation. He sees all the varieties of vegetable nature re- ducible to four elements, and animal products in general made up of the same number, and yet there is no end to their com- binations, and none can tell the limits within which the changes of nature wrought through the aid of such scanty materials must be confined. Yet this beautiful simplicity has hitherto rendered the study of her combinations perplexing, and we have been. unable often to discover such differences in atomic constitution as at all to account for the diversities in external appearance and character of many vegetable and animal sub- stances. But our knowledge is enlarging, and, as the resour- 82 Berzelius’s yearly statement of the progress of ces of organic analysis become greater, it is to be hoped that we shall by degrees attain, if not to a complete, at least toa much less imperfect view of the chemical constitution of orga- nized bodies than we can yet boast of. The new researches under the head of vegetable chemistry most deserving of attention in the volume before us, are the Equisetic acid, found by the industrious Braconnot in the Lgui- setum fluviatile—an acid discovered by Runge in the Scabiosa succisa, which he calls @reen acid—a vegetable salt basis, found by Brandes in the Chiococca racemosa—another vegetable al- kalinamed Atropin, extracted from the Atropa Belladonna by Ranque and Simonin—a third, by Dana, in the root of ‘the Sanguinaria Canadensis, which he » calls Sanguinarin—a fourth, by Pelletier, from the bark of a: species of Cinchona, called China de Calysaya or China de Carthagena—a fifth, Salicin, prepared by Buchner from the bark of the Salia pen- tandra—and a sixth, which is the most remarkable of them all, being deliquescent, extracted by Boussingault from a sub- stance called Curara,; sold in South America for poisoning hunting spears, and which, according to Humboldt, is pre- pared from the juice of a tree analogous to the Strychni. Of substances possessing neither alkaline nor acid properties, Bonastre has discovered one peculiar to the wax of Ceroaylon andicola, a crystalline fatty matter, which he has called Ce- roxylin—another, in the Conium maculatum by Brandes and Giesecke, half-a-grain of which kills a dog with. the . same symptoms as Strychnin, and which has been called Coniin—a third, by Dulong d’Astofort, ih the Plumbago Europea, named Plumbagin—a fourth, Hesperidin, by Lebreton in unripe pomegranates—and a fifth, Z'remellin, by Brandes in the T'remella mesenterica, and which bears to it the same relation as fungin to the mushroom tribe. Camphor.—Libri has mentioned a, curious circumstance re- garding odoriferous bodies such as camphor,—that if they be exposed to a current of electricity for a considerable time, their smell diminishes, and at last disappears, entirely. After, a lapse of time, camphor again recovers the ‘power of Wis. 9. odours. Animal Chemistry. —We bow ‘only. space to notice i ol Chemical and Physical Sciences. 33 his head the very interesting experiments of Wohler on the artificial formation of Urea. It is one of those rare results which approximate the productions of art to those of nature, and lay open the possibility of imitating her in some of her elaborations, though they unfortunately afford little ground for the flights of those airy speculators who hold up the pro- bability of our being soon able to dispense altogether with the agency of nature in the production of the animal and vegetable substances, upon which we at present depend for our exist- ence. If Cyanite * of silver be treated with a solution of sal-ammo- niac, or cyanite of lead with caustic ammonia, there is formed, instead of cyanite of ammonia, a crystalline matter which has all the properties of pure urea, and which therefore is Urea. The constitution of urea, according to the analysis of Prout, compared with that of one atom each of ammonia, shah acid, and water, is as follows : . Urea. * Cyanite of ammonia. ‘Hydrogen, 2 atoms. 4: atoms. Carbon, | Q Oxygen, 1 2 Azote, 1 g From which we see that the elements in both are in the same proportion, which confirms the experiments of Wohler. Yet urea is not a cyanite of ammonia, for stronger bases do not develope ammonia. ‘The atoms, therefore, must have com- bined themselves in a different manner, so that the cyanite of ammonia, from being a compound atom of the second, has pas- _ sed to the state of a compound atom of the first order. This is one of those few examples from which we can accurately and strictly deduce the law, that the same number of single atoms may combine in different ways, so as to produce bodies of very different characters and properties. Geology.—In connection with geology, we shall advert to C. G. Gmelin’s elegant examination of clinkstone. He has * This is prepared with Wohler’s acid, which we have shown above must be called the Cyanous, and its compounds, of course, Cyanites. NEW SERIES. VOL. Ill. NO. 1. JULY 1830. Cc : 34 Berzelius’s yearly statement of the progress, &c. found that this volcanic rockis an aggregate of mesotype and felspar. He shows this in a very interesting way. He treats the mineral with muriatic acid, and separates the dissolved portion, after which the silica of the decomposed part is dis- solved out by boiling with carbonate of potash. In the meso- type, a portion of the soda is compensated by potash and lime, and a part of the alumina by peroxides of iron and manganese, and in like manner, in the felspar, a part of the potash is com- pensated by soda and lime, and of the alumina by oxides of iron and manganese. In this investigation the water in the mesotype was found to be less than in the same substance when crystallized. ‘The water might possibly be merely hy- droscopic, as its quantity in the mineral varied from 0.638 to 3.19 per cent. It is probable that the application of this prin- ciple to other rocks might be productive of very interesting results, and might throw light upon geological formations, which we shall seek in vain from the analysis of specimens of ‘rocks in their aggregated state. We have left ourselves no room for further remarks on this very interesting work. Its nature, and the ability of its exe- cution, will appear, we think, from the various extracts which we have made. With one or two exceptions from the pen of the first chemist in Scotland, no analyses of Swedish chemical works, we believe, have appeared in our language—certainly no such account of the yearly reports of Berzelius has ever been inserted in the English journals, and for these reasons, . independént of the many facts we haye taken occasion to lay before our readers, we hope the present article may not prove wholly uninteresting. Such, a work as this of Berzelius is a great desideratum in our own country. Could any able che- mist be persuaded to devote his time to such a labour, and could he find a bookseller sufficiently public-spirited, men of . science would receive a most valuable itt. Mr Harris’s Experimental Inquiries, &c. 35 Arr. I1.—Experimental Inquiries concerning. the Laws of Magnetic Forces. By D. Snow Harris, Esq. of Ply- mouth. Communicated by a Correspondent. Tue limits of this work prevent our giving more than a brief abstract of the results detailed in this interesting article from the Yransactions of the Royal Society of Edinburgh, vol. xi. It may be divided into'two parts; Ist, A descrip- tion of an apparatus invented by the author, which affords every facility for examining the intricate phenomena of in- duced magnetism. Its principal parts are a graduated. per-— pendicular bar, surmounted by a divided quadrant ; near the top of the bar is fixed a wheel, of which the axis rests on fric- tion wheels. As this wheel, when in use, never makes. an en- tire revolution, the part which stands uppermost, when at rest, is on the circumference supplied with a slight projecting arm, which serves as an index to the quadrant. A light thread passes over this wheel, (being fastened thereto,) to one extre- mity of which a light magnet or piece of iron (as occasion may require) is attached, and to the other a counterpoise adjusted so as to be of equal weight thereto. The'delicacy of this ma- chine is sufficient for the’ most’ minute imvestigations. 2d, The results obtained by the use of this apparatus: The quan- tity or force of magnetism induced in a bar of soft iron’ by the approach. of a magnet is indicated by a piece of iron A, suspended from the wheel; beneath this is fixed the iron un- der experiment I, and below this a magnet M, is placed, the distance A I being constantly 0.2 inch. Taste [I. Distance I M. Force induced. eau 3. 0.8 | 4, 0.6 5. 0.5 6. 0.4 15 0.3 : 10. of 15. ° 36 Mr Harris’s Experimental Inquiries Hence it follows that the magnetic developement induced in the iron increased in an inverse simple ratio of its distance from the magnet. The truth of this receives confirmation from the weights required to break the contact of A and I, M be- ing now placed .upermost, and A below and in contact with I, Taste II. Distance I M. Weights in grains. Mean weight in grains required to break contact A I. 4. between 190 and 210 200 3. 250 and 280 265 2. 390 and 400 | 400 1 a little less than 800 800 But this mode of ‘experimenting is not so accurate as the former. The same result obtains when the iron I and the magnet are placed horizontally, and the index iron A or dicularly. *< This law of magnetic induction is observed to proceed uni- . formly from the distance at which the force first becomes measurable, until the iron and magnet are very nearly ap- proximated, but then begins to vary. Thus when they were approximated within 0.1 inch, the.increments in the attractive force began to diminish. From this it would appear either that the similar and distant polarities begin to exert a sensible influence, or that a limit exists approaching saturation, beyond which the inductive effect on the iron does not .proceed with the same facility as before. 1n either case this liniit may be supposed to vary with the power of the, magnet. This was found to be the case by using successively magnets of differ- ent degrees of intensity ; the induced effects being at first pro- portional to the power of the magnet, but the increments of force by approximation begin to diminish at a greater or less - distance in proportion to the intensity of the original magnetic force. Cateris paribus, the attractive force of magnets by in- duction at their distant poles is inversely: proportional te the lengths of the iron; and, as before observed, proportional to the powers of the inductive magnets.” The distances of M, I | in the experiments referred to in the following tables= 0.3 inch, and I, A — 0.2 inch. concerning the Laws of Magnetic Forces. | 37 Taste ITI. Position of M I vertical.’ Position of M I horizontal. Length of iron I. Foree induced Length of iron I. Force induced 5° == 1 gr. ue 5o #4° . United Hills, 58 8,25 6,5 7,6 4,3 38,5 Crinis, . 56+ 6,75 6,75 9,1 5,8 44,38 Huel Unity, 52 6,666 5,75 9,1 6,4 33,7 60° 7,25 5,75 ° 138,8°° 5j8 > B2@r- Poldice, 90 10, = 7, 10,5 5,3 46,6 60 9,5 6,25 12,8 5,9 47,3 - Huel Damsel, - 42¢ 17,5 5,75 21, 4,6 $2:9- 50 = (9, yf 9,6 3,2 $234 Ting Tang, - 63 8, 6, 14,2 4,4 45,3 — 66 9, 7,5 11,6 3,8 44,9 Cardrew Downs, 66 8,75 7, 10,4 5,9 58,4 Huel Harmony, 70 9,25 7, 8,8 "5,2 $5,1 Huel Montague, 50 9, 7, 11; 2,5 26,.; Dolcoath, . 7 9; 75 11,8 48 41,5 Great Work, - 60 9, 7, Huel Penrose, 3668.5 6,5 11°" 7,4 Bon Huel Caroline, Ds T 6, 29,3 8,4 32,1 53,5 8,333 7, 1,6" 5,8: aes Huel Towan, Mr Henwood s. Accownt of Steam. Engines in Cornwall. 4% bag, HOG ba et §. g22s2 SH BOD cS 3S Bs Sees? _ Mines. $8 585 294 5°28 Jf 82SFs Be Pee PREF gon CF aeees O88 AS ABA As 2k SESS- St. Ives Consols, 36° 7, 7, 16, 6,1 = 27,9 Lelant Consols, 15 7,5 4,5 17,2 26 10,5 Binner Downs, 70 10, 7,5 10,9 8, 61, yore 64 9,333 7,75 7,7 9,6 51,3 42 YQ, 7,55°°18.8 °° 7, 40,4 ConsolidatedMines,90 10, 1,5° 58,9 70 10, 7,5 10,4 6,4 62,3 65 9, 7,5 15,9 34 59,6 90 10, 7,5 8.7 74 59, 90 10, 15 10,3: 3,4 38,7 | 65. 9, 7,5 12,4 4,9 64,7 United Mines, 90 9, 8, 7,9 4,6. 43,9 Se a 7,5 12.9 83. 42,4 Huel Beauchamp, 36 17,75 6,* 13,5 4,7 386, Huel Rose, -. 60. 9, 7, 14, 6,6. 60,1 Pembroke, 80. 9,75 7,25 11,3 3,4 48,8 BO. Dp. To | WQyAe Tel. 4 East Crinnis, - 60. 5,5 5,5 $.5...:3.8 «20.7 70 10, YO 9,4 3,5... 33,8 East Huel Unity, 45 8,75 6,75. 13,1. 3,6 38,4 Huel Hope, - 60 9, 8, 11,7... 5,6. .53,5 Huel Tolgus,, 70. 10, 7,5 8.4 5,5. 57,4 Tresavean;., .-,.. 60... 9,..:...% 7,7. 4,5>....22;4 Huel Falmouth, 58 8,75. 6,5 4,1. 4,1....24,2 Huel Sperris, - 70 10,333.7,75 6,7 6,1 39,5 Huel Prosper, - 53. 7%, , a 4,2. 5, 26,6 Huel Leisure, - 36 9,25 6,75. 14,3 7,9 35,9 | 70... 9,833 7,75. 5,1. 339, . 38, Marazion Mines, 60 9, 8, 5,2 82. 47,8 ® co ash or Average. duty 41,58 millions. of lbs. weight lifted one foot high by the consumption of one bushel (84 Ibs.) of coal. Watt's rotatory double engines employed to move machinery for bruising tin ores. > 48 Dr Hancock’s Experiments with Laurel Oil. Length of crank, Huel Vor, 24. 6. 6. 12. 16.1 17.7 Q'7. 5. 5. 12. 17.6 19.3 165. “5. 5. 8.5 26.6 12.6 - Average duty of rotatory engines, 16.5 millions. * Watt’s double engines. + Trevithick’s high pressure combined with Watt’s single —for March, Watt’s single only. {| For one month only. Erratum.—In the Report for July, August, and September 1829, Huel Damsel Engine, 50 inches cylinder, for duty 136.6 millions, read 36.6 millions. Art. IV.—Notice of experiments with Laurel Oil. By Dr Hancock. Communicated by the Author. I sxtieve it is understood to be a fundamental principle in hydrostatics, that when two immiscible fluids are added together, the heavier of the two has a tendency to displace the other, or to uccupy the bottom of the vessel. It appears indeed, a self- evident truth, and scarcely necessary to be stated as an axiom, founded as it is upon the universal principle of gravitation. It may therefore appear paradoxical to assert the contrary of any two bodies,—and I have hesitated whether I could safely state the following fact, being apprehensive of some fallacy in my own senses or mode of considering the subject, and it is chiefly with a view of acquiring information, that I am now induced to offer it to the attention of the scientific chemist. The fact I wish to notice is this: When we add together a portion of sulphuric ether and proof spirit in equal parts, and of laurel oil, the latter, although a fluid of greater speci- fic gravity, invariably occupies the upper part, or floats upon the surface of the compound of ether and proof spirit. 'The re- sult is identical whether we pour in the oil or the compound first, and in whatever proportions. they may be added,—and whether we shake the vial, or put them together in the most Dr Hancock’s Experiments with Laurel Oil. 49 gentle manner. * | How is this to be accounted for? Is. not the buoyancy of fluids an invariable criterion of their specific gravity ? Intending to try the effect of washed ether with the native oil, I added to water some ether from a druggist’s shop in George Town.—I found I could not wash) this ether, for it mixed or combined with water in every proportion, I hence ~ concluded it to be impure, or acompound of ether and diluted alcohol. ++ T then tried by the same tést, a portion from an- other druggist’s, and I found I could wash this ether; and that it only took up about a tenth of its bulk of water,—of course it proved to be genuine. The next step was to mix the genuine ether with strong spirit. I added equal parts of these together; they formed a clear transparent solution or mixture. The spirit was double distilled rum, proof 23,1 by the glass bubble,—the only hy- drometer I could obtain, and indeed the only one I know of conveniently adapted for proving the specific gravity of small portions of fluids. I found this mixture of ether aud proof spirit to smk the bubble 1'7, then adding this to the native oil of proof 21, the laurel oil was found to float upon the surface of the ethereal alcoholic mixture, although it was 4 degrees or 4 bubbles heavier, as indicated by the glass bead hydrometer; if this may be considered any test of the specific gravity of fluids. _ The steps by which we arrive at a certain result, may often re- veal others not less interesting than the object directly sought for. In the course of this examination I have found, that the greater part of our ether is adulterated either here, or before it is sent out from Europe. Of four different samples I have recently * The phenomena cannot therefore be the result of tenacity or cohe- sion. + This it may be useful to notice as a test of genuine ether. { I afterward employed strong high wines and ether in equal parts, and with the same result but slower. I also find it identical in the result, whether we employ the native oil in its usual specific gravity, i.e. proof 18, or that which by long standing and exposure has acquired the gravity of 21 or more,—in the latter case, exceeding the ethereal alcoholic mixture on which it swims, by 5 or 6 grades of the hydrometer. NEW SERIES, VOL. III. NO. I. JULY 1830. D 50 Di Hancock’s Experiments with Laurel Oil. tried, only one has proved to be genuine; two of these samples appeared to contain less than a fourth part of real ether. With genuine ether the laurel oil dissolves or mixes in every. proportion, but: not \so.if the ether is in the smallest degree adulterated. | Subsequently I found a similar result with high wines and laurel oil, but slow, and Jess sensible, the affinities of the oil being much weaker for alcohol than for ether. Should there be a portion of water or spirit mixed with the ether, it becomes sensible in the turbid mixture ensuing on the os tion of the laurel oil. The composition which, after many trials, I find to onal the effect with the most striking celerity, is that with equal parts of ether and common spirit, proof 28. It will be good to add the ether in full equal proportion, or rather exceeding that of the spirit, to render the effect more certain and con- clusive. The compound with brandy, proof about 26, es very well; but not equal to that of proof 30. With spirit proof 32 the ether does not mix at all, remaining separate in the same vo- lume as added. ~ In these results, there can be no doubt, I think; that the seemingly strange phenomena proceed from the strong affinity and combination of the laurel oil with ether, by which it is attracted and separated from the water and alcohol. . This was afterwards proved by adding together pure ether and) pure laurel oil, when I found them intimately combine as oniney observed. I have also observed that the laurel oil evaporated, to. the consistence of Marana balsam will also float on the same, com- pound, and the Marana, or Balsam Copaivi even to rise slowly, and float on it. Onadding the Marana, and preparatory to its rising in the ethereal compound, we see an active ‘chemical process take place. In an experiment with iodine and laurel oil, by throwing the former on the latter, a violent action or crepitus was in- stantly produced, bordering on combustion, or rather like sparks of fire or a fine coal thrown into water. At the instant of con- tact, much heat was evolved, and a bituminous odour, (as of hydrogen gas,) but-no light ; the oil received a bright red’co- Dr Hancock on revolving motions in Laurel Oil. 5k lour, but extremely fugacious, and in a few minutes the co- Icur entirely vanished. It is probable that hydrogen gas was disengaged on the decomposition of the fluid by the iodine. In anothér trial, when iodine was added in a larger propor- tion, the result was.a black substance similar to petroleum or Barbadoes tar, in colour, taste, and smell. Many naturalists have suspected amber and the bituminous substances to be of vegetable origin. The striking analogy above noticed, brought this more forcibly to mind, enid impressed me with the idea that such might be the case,—that bitumens might also be the result of vegetable exudations, variously modified by the agency of soda and divers minerals? Or is it more ra- tional and natural to conclude, that, on the contrary, these sub- stances exist in the original structure of the earth, and that. they are absorbed by the roots of vegetables, exuding under various modifications, as varied as the vegetables which give them out?* If such were the case, we might expect to find some traces of the bitumens in the soil where such resinoids ot terebinthous vegetables abound, unless they have the property of elaborating these various resinoid matters from other elements. _ It would be interesting, and perhaps throw some lhght,on the subject, if the soil where these kind of trees grow most abundantly, were carefully analyzed with this view and com- pared with that of other parts. . . The compound of. iodine and laurel oil coloured ane of wine of a light amber tint, but does not dissolve in it nor in water. Art. V.— Account of a curious phenomenon of revolving mo- tions, produced by the combination of Alcohol with Laurel Oil. _ By Dr Hancock, Communicated by the Author. To exhibit a singular spectacle which seems to bear some ana- logy with the motions of the planetary orbs, take a vial of the * The.Courida tree, ( Avicennia nitida ) is found thus to take up sea salt and deposit it on the leaves ;—it is only on salt land, however, where this oc- curs, as the same tree placed at a distance from the sea gives no salt; and this is the only vegetable on which I have found salt thus deposited. In a severe dry season, the salt is seen like hoar frost on the leaves, \ ( > 52. Dr Hancock on revolving motions in Laurel Oil. laurel oil and drop into it, at different intervals, some rectified spi- rits of wine, when the most interesting results will be observed » to ensue ; a circulation presently commencing, of globules of al- » cohol up and down through the oil, which will last’ for many hours, or for days, (how long is unknown.) A revolving or cirs | culating motion also appears in the oil, carrying the alcoholic | globules through a series of mutual attractions and repulsions, —the round bodies moving freely through the fluid, turning » short in a small eccentric curve at each extremity of their» course, passing each other rapidily without touching ; but after a time, they seem to acquire a density approximating to that. of the lower stratum, which appears to be an aqueous portion, separated by the ethereal oil from the alcohol; and this assi- ‘milation taking place, the globules, after performing many revolutions, will fall flat wpon the surface, and unite =" the lower or watery stratum. The orbits of those small globules being confined ‘e the glass are very eccentric. In the course of the experiment, I observed particles of the fluid to separate in larger globular’ portions ; these: commenced a similar revolution, and smaller) ones quitted their course and revolved about the larger, whilst the latter still pursued their course after the manner of pri- mary planets and their secondaries. This, however, can only be well understood by seeing the experiment, which is:easily performed, and well worth the trouble; as it appears to me, that, if attentively studied, it might furnish important deduc-: tions, and serve, we know not how far, towards an illustration: of the celestial motions. ish In the present case, the revolving motion of these globules’ appeared to be, not as we are accustomed to regard the plane- tary motions, as the effect of a direct attractive and repulsive power, in combination with a projectile force, but as revolving in a circulating medium, attended by an emanation from the globules ene oealyes | This experiment was performed witha small vial. Perhaps a larger one would render the result more perspicuous. oe Mr Adam’s Description of a Rain-Gage. 53 Art. VI.—Description of a simple, cheap, and accurate Rain- Gage, calculated to show the depth of rain falling around it — to the ten-thousandth part of an inch. By Marrurw Apam, A. M., Rector of the Academy of Inverness, and Associate of the Society of Arts for Scotland. .Communi- cated by the Author. Tis instrument, is composed of four parts, represented in Plate I. Fig. 1. viz. Ist, A painted square-mouthed tin-plate filler, ABZ C Dm, for collecting the rain water, having the length of each side, A B, A C, &c. of its mouth equal to ten inches, and consequently its, superficial area equal to 100 square inches. About half-an-inch of its mouth is turned perpendicularly up, to prevent any part of the rain which has entered it from being blown out again by wind ; and its throat D is nearly closed by a piece of tin-plate pierced with ten or twelve holes, each about one-eighth of an inch in dia- meter, to permit the descent of the rain water, and to retard its rising again through the neck-of the filler by evaporation. 2d, A large bottle E F G, which admits into its mouth E, a part of D m, the neck of the filler, and holds nearly one-half of an imperial gallon, so that it may contain all the rain which at any time may enter it, through the filler, in the course of twelve hours. 3d, A cylindrical glass tube or measure K L, whose inside diameter may be 3, §, or 7, of aninch. Its lower extremity L, is closed ; its upper extremity K4, isenlarged, or funnel-shaped, that the rain may be all easily poured into it from the bottle ; - and on one side, it is accurately graduated from L to K, into portions having the capacity of cubic inches and tenths of a cubic inch. 4th, An inch plank, or post D I, of convenient length, firm- ly fixed vertically in a sheltered situation selected for it, with three appendages, viz. lst, A horizontal shelf H G, perpendi- cular to D I, and about 33 feet above ground, for the purpose of supporting the bottle.. 2d, A bent iron hoop cde, screwed or nailed to the post at ¢ and ¢, for the purpose of holding the bottle firmly im its place, when exposed to storm. And 3d, ‘Two strong iron wires f 2, hi, driven or screwed into the 54 Mr Adam’s Description of a post at g and i, and bent into circular apertures at f and h, so as conveniently to hold the graduated glass measure K L, that it may be ready, when required, to ascertain the number of cubic inches, and tenths, and hundredths, of a cubic inch of the water which has entered the bottle, and consequently also the depth of the rain then fallen in the adjacent country, in hundredth, thousandth, and ten-thousandth parts of an inch. Ezxplanation.—The superficial area of the mouth of the filler being 100 square inches, it is obvious that 100. cubic in- ches of rain water must enter through it into the bottle, when one inch deep of rain falls in the adjacent country, and that every cubic inch of this water, bemg the. hundredth) part of the whole, must indicate the hundredth part of an inch de of rain. Consequently every tenth and hundredth part ofpa cubic inch of the same water, measured in the graduated glass — tube K L, must likewise indicate the thousandth ane ten- thousandth part of an inch deep of rain. sonnel? If the inside diameter of the cylimdrical glass measure KL be only half-an-inch, the circular area of a section: of it, viz. .19635, or a littlciess than }° of a square inch, will be contain- ed 509, and nearly § times in 100 square inches, the area of the square mouth of the filler; and, as the depth of measures of equal capacity are reciprocally as the areas of their bases, or corresponding sections, it is clear, that, to measure 100 cubic inches of rain water, which may be contained in one inch deep of the square mouth of the filler, there would be ‘re- quired a depth or length of 509 inches. of the cylindrical _ glass measure, whose diameter is only half an inch. Consequent- ly the hundredth part of this length, or five inches and nearly #5 of an inch of this measure, will be required to: contain one cubic inch, or to measure the hundredth part of an inch deop of rain. Half-an-inch of it will be required to contain 74 of a cubic inch, or to measure the thousandth part of an fiich deep of rain; and consequently the tenth part of half-ancinch or a length equal to y of an inch of this measure, will:bere- quired to contain the hundredth part of a cubic inch or to measure the ten-thousandth part of an inch deep of rains And it is obvious that a depth, or length, much’ smaller than’ the twentieth of ‘an’ inch ‘can ‘easily be aga bla oF teed — without the aid of a magnifier. : i a re simple, cheap; and accurate Rain-Gage. 55 - If-asimilar measure of 3 or } of an inch in diameter be gra- duated in the same manner, the ultimate divisions of) such measure, even when carried only to tenths of a cubic: inch, are therefore sufficient to enable a careful observer to deter- mine the depth of rain fallen around the gage, to the ten-thou- sandth part of an inch. In regard to expence—The tin-plate filler, the large bottle; and the wooden post with its appendages, may all, it is believ- ed, be obtained for 3s. 6d. or little more than one shilling each; and the glass measure, properly graduated, may be pur- chased at Knight’s Chemical Instrument Warehouse, in Lon- don, for 2s. or 2s. 6d. The whole may therefore be procured for about 6s.—a price extremely moderate compared with that of the rain-gages usually sold at four or five guineas each, and which show the depth of rain falling around them only to the hundredth part of an inch. If only a graduated measure, a tin-plate filler, and a com- ‘mon bottle, sunk four or five inches in the ground were used, the whole expence would probably not exceed 3s. 6d. or 4s. But during great rains a smal] bottle would not contain all the rain entering it through the filler in the course of only five or six hours; a circumstance which would render the use of a small bottle very inconvenient, particularly during the night. Mr Adam’s rain-gage, of the kind now described, has been used since the 18th of September last, and appears to him to answer its purpose well. For though the mean inside diame- ter of the graduated measure is upwards of { or nearly .9 of an inch, and diminishes a little from top to bottom, so that the distance between the divisions, marking ;; of a cubic inch, varies from #, to 35; of an inch ; yet he can easily apertre by it the depth of rain falling around the gage to the ;5$55 part of an inch. The depth of rain is therefore entered in the register in in- ches and four decimals of an inch; the first two decimals being obtained from the cubic inches, and the last. two from the tenths and decimals of the tenth of a cubic inch, marked on the graduated measure. Thus a quantity of rain measuring seventeen cubic inches, eight-tenths, and eight-hundredths of a cubic inch in the graduated measure, is marked in the regis- 56 Mr Adam’s Description of a ter .1788 of an inch deep of rain, and a‘ quantity measuring only two-hundredths of a cubic inch in the graduated mea- sure, is marked in the register .0002, or two ten-thousandth parts of an inch deep of rain. This last, it is true, is an ex tremely minute quantity of rain.. But there are many such minute entries in the register, varying from one to fifteen ten- thousanth parts of an inch. | And it-is remarkable, that most of them are noted as miniature showers, or depositions of dew, from the air inclosed in the bottle; because these miniature showers or depositions of dew were then observed to vary in quantity with the variations of sky and temperature, and to take place frequently at periods when the sky was clear, and always when so entered, at times when no rain fell from the external air. These entries, thus noticed, may therefore, it is apprehended, be considered as measurements of the varying quantities of dew deposited by the air contained in the bottle, under the varying temperatures and states of the weather then noted in the register. | Explanatory Notes. 1s¢, 10 inches ~ 10 = 100 square inches, = the area of the quate mouth of the filler of Mr Adam’s rain-gage. 4x 3.1416 x 3 x 4 = .7854 x 4— .19635 ofa square inch, = the area of a ee section of a tube whose diameter = } inch. Now 100 x 1 inch deep — .19635 x J inches deep. Therehans 100 ~~ .19635 = 509.2946, or 509.3 lineal inches nearly = / = the length of a glass tube, (whose diameter = } inch,) requir- ef to contain 100 cubic inches, or to measure 1 inch deep of rain. —_ — 5.09 inches = 5xinches nearly = length of tube con- taining 1 cubic inch, and measuring one-hundredth part ¢ of an inch deep of rain, = m. o> il 64 _ . Mr Babbage’s observations on the of half that loss, judiciously applied to the encouragement of. mathematical science, would, in a few years, have rendered: | utterly impossible such expensive errors. ; To those who bow to the authority of great names, one re- mark may have its weight... The Mecanique,Celeste,* and, the Théorie Analytique des Probabilités, were both dedicated, by Laplace, to Napoleon. . During the reign of that extraor- dinary man, the triumphs of France were as eminent in science’ as they were splendid in arms., May the institutions, which trained and rewarded her philosophers be permanent as the benefits they have conferred upon mankind ! In other countries it has been found, and is admitted, that a knowledge of science 1s a recommendation to public. ap- pointments, and that a man does not make.a worse ambassa- dor because he has directed an observatory, or has added by his discoveries to the extent of our knowledge of animated na- ture. Instances even are.not wanting of ministers who have begun their career in the inquiries of pure analysis. , As such examples are perhaps more frequent than is generally i imagin- ed, it may be useful to mention a few of those men of science who have formerly held, or who now hold, high official sta- tions in the governments of their respective countries. Country. Name. mires A Public Office. France . Marquis Laplace}. . Mathematics . . President of the Conservative — Senate, > France... .M.Carnot..... Mathematics . . Minister of War France .. Count Chaptalt.. Chemistry ... Minister of the Interior. France... Baron Cuvier§.... Comparative Minister of Pub- Anatomy, iic Instruction. Natural His- tory : sine Prussia .. Baron Humboldt .. Oriental Lan- Ambassador to guages England. * The first volume of the first translation of this celebrated work into our own language, has just arrived in England from _ Ammen. + Author of the Mecanique Celeste. s8 + Author of Traité de Chimie Appliqué aux Arts. His de § Author of Legons d’ Anatomie Comparée—Reécherches sur les, Ossemens Fossiles, &c. &e. | . National Encouragement of Science. — 65, Department of Country. Name. — Ry Public Office. nth a Prussia... Baron Alexander The celebrated Chamberlain to Humboldt Traveller the King of Prussia. © Modena .. Marquis Rangoni* Mathematics . . Minister of Fi- nance and of. Public In- struction, President of the Italian Academy of Forty. Tuscany. | Count Fossombronit Mathematics .. Prime Minister of the Grand Duke of Tus- ; cany- Saxony.. M.Lindenaut ... Astronomy ... Ambassador. M. Lindenau, the Minister from the King of Saxony to the King of the Netherlands, commenced his career as astro- nomer at the observatory of the Grand Duke of Gotha, by whom he was sent as his representative at the German Diet. On the death of the late reigning Duke, M. Lindenau was invited to. Dresden, and filled the same situation under the King of Saxony; after which he was appointed his minister. at the court of the King of the Netherlands. Such occur- rences are not to be paralleled in our own country, at least not in modern times. Newton was, it is true, more than a century since, appointed Master of the Mint; but let any person sug- gest an appointment of a similar kind in the present day, and he will gather from the smiles of those to whom he proposes it that the highest knowledge conduces nothing to success, and, that political power is almost the only recommendation. Of Encouragement from Learned Societies. There are several circumstances which concur in inducing persons pursuing science, to unite together, to form. societies * Author of Memoria sulle Funzioni Generatrici, Modena, 1824, and of various other memoirs on mathematical subjects. + Author of several memoirs on mechanics and hydraulics, in the T’rans- actions of the Academy of Forty. t Author of Tables Barometriques, Gotha, 1809— Tabule Veneris, nove et correcte, Gothe, 1810—Investigatio Nova Orbite a Mercurio circa Solem descripte, Gothe, 1813, and of other works. NEW SERIES, VOL, III. NO, 1. JULY 1830. E 66 Mr Babbage’s observations on the or academies. In former times, when philosophical i instruments were more rare, and. the art of making experiments was less perfectly known, it was almost necessary. © More recently, whilst numerous additions are constantly making to science, it has been found that those who are most capable of extend- ing human knowledge, are frequently least able to encounter the expence of printing their investigations. It is therefore convenient, that some means should be devised for relieving them from this difficulty, and the volumes of the Transactions of academies have accomplished the desired end. | There is, however, another purpose to which academies con- tribute. When they consist of a limited number of persons, eminent for their knowledge, it becomes an object of ambition to be admitted on their list. Thus a stimulus is applied to all those who cultivate science, which urges on their exertions, in order to acquire the wished-for distinction. Itis clear that. this envied position will be valued in proportion to the diffi- culty of its attainment, and also to the celebrity of those who enjoy it; and whenever the standard of scientific knowledge which qualifies for its ranks is lowered, the value of the dis- tinction itself will be diminished. If, at any time, a multitude of persons having no sort of knowledge of science are admitted, it must cease to be sought after as an object of ambition by’ men of science, and the class of persons to whom it will be~ come an object of desire will be less intellectual. 12 Let us now compare the numbers composing some of the various academies of Europe.—The Royal Society of London, the Institute of France, the Italian Academy of Forty, and the Royal Academy of Berlin, are amongst the most aie: tinguished. Name. Number of Number Population. Members of its OFT Country- Academy. Foreign Members. 1. England . . 22,299,000 685 50 8 Mem... @. France ee 32,050,000 75 100 Corr. | 3 3. Prussia... 12,415,000 38 16 b. Ttaly oc nl 12,000,000 PF ih lp ey It appears then, that in France, one person out of 427,000 is amember of the Institute. That in Italy and Prussia, about ee ee —— a —r aT ar a a i i Sis ca National Encouragement of Science. 67 one out of 300,000 persons is a member of their academies. That in England, every 32,000 inhabitants produces a Fellow of the Royal Society. Looking merely at these proportions, the estimation of a seat in the Academy of Berlin, must. be more than nine times as valuable.as a similar situation in Eng land; and a member of the Institute of France will be more, than thirteen times more rare in his country than a Fellow ro the Royal Society is in England. Favourable as this view is to the dignity of such situations in other countries, their comparative rarity is by no means the most striking difference in the circumstances of men of sciences If we look at the station in society occupied by. the savans of other countries, in several of them we. shall find it high, and their situations profitable. Perhaps, at the present moment, Prussia is, of all the countries in Europe, that which bestows the greatest attention and most unwearied encouragement on science. Great as are the merits of many of its philosophers, much of this support arises from the character of the reigning family, by whose enlightened policy even the most abstract sciences are fostered. The maxim that “ knowledge is power,” can be perfectly comprehended by those only who are themselves well versed in science ; and to the circumstance of the younger branches of the royal family of Prussia having acquired considerable know- ledge in such subjects, we may attribute the great force with which that maxim is appreciated. In France, the situation of its savans is highly respectable, as well as profitable. If we analyze the list of the Institute, we shall find few who do not possess titles or decorations ;_ but as the value of such marks of royal favour must depend, in a great measure, on their frequency, I shall mention several particulars which are probably not familiar to the English reader. * * This analysis was made by comparing the list of the Institute, printed for that body in 1827, with the Almanach Royale for 1823. « 68 Mr Babbage’s observations on the - Number of the Members of the Total Number of each ., Institute of France who belong to the class of the ) Legion of Honour. Legion of Honour. Grand Croix “ 3 80 Grand Officer - 3 160 Commandeur . 4 400 Officer © : “ 17 2,000 Chevalier ae Not limited. Number of Members of the Institute Total. Number decorated with of the Order of St. Michel. that Order. Grand Croix 3 Q o \ 100 Chevalier - ~ Amongst the members of the Institute there are,— Dukes - - . 2 q Marquis - - et feud Counts : . 4 Viscounts “4 . Q Barons . - 14 23 Of these there are Peers of France 5 We might, on turning over the list of the 685 members of the Royal Society, find a greater number of peers than there are in the Institute of France; but a fairer mode of instituting the comparison, is to inquire how many titled members there. are amongst those who. have contributed to its Transactions. In 1827, there were one hundred and nine members who had contributed to the Transactions of the ict Society ; amongst, these were found :— Peer ae a wie Baronets . - - 5 Knights -..- sin SD It should be observed, that five of these titles were the re- wards of members of the medical profession, and one only, that of Sir H. Davy, could be attributed exclusively to science. } {risa National Encouragement of Science. 69 - It must not be inferred that the titles of nobility in the French list, were all of them the rewards of scientific eminence; many are known to have been such ; but it would be quite suffi- cient for the argument’ to mention the names of Lagrange, La- place, Berthollet, and Chaptal. The estimation in which the public hold literary claims in France and England, was curiously illustrated by an incidental expression in the translation of the debates in the House of Lords, on the occasion of His Majesty’s speech at the com- mencement of the session of 1830. The Gazette de France stated, that the address was moved by the Duc de Buccleugh, << chef de la maison de Walter Scott.” _Had-an English editor wished to particularize that nobleman, he would undoubtedly have employed the term wealthy, or some other of the epithets characteristic of ‘that quality most esteemed amongst his countrymen. If we turn, on the other hand, to the emoluments of science im France, we shall find them far exceed those in our own country. I regret much that I have mislaid a most interesting memorandum on this subject, which I made several years since: but I believe my memory on the point will not be found widely incorrect. A foreign gentleman, himself possessing no inconsiderable acquaintance with science, called on me a few years since, to present a letter of introduction. He had been but a short time in London; and, in the course of our conver- sation, it appeared to me that he had imbibed very inaccurate ideas respecting our encouragement of science. Thinking this a good opportunity of instituting a fair com- parison between the emoluments of science in the two countries; I placed a sheet of paper before him, and requested him to write down the names of six Englishmen, in his opinion, best known in France for their scientific reputation. ‘Taking an- other sheet of paper, I wrote upon it the names of six French- men, best known in England for their scientific discoveries. We exchanged these lists, and I then requested him to place against each name (as far as he knew) the annual income of the different appointments held by that person. In the mean- time, I performed the same operation on his list, agamst some names of which I was obliged to place a zero.. The result of 70 Mr Babbage’s observations on. the ’ the comparison was an average of nearly L. 1200 per annum for the six French savans whom I had named. Of the average amount of the sums received by the English, I only remember that it was very much: smaller. When, we consider what a command over the necessaries and luxuries of life L. 1200 will give in France, it is underrating it to say it is equal to L. 2000 in this country. Let us now look at the prospects of a young man at his en- trance into life, who, impelled by an almost irresistible desire to devote himself to the abstruser sciences, or who, confident. in the energy of youthful power, feels that the career of science is that in which his mental faculties are most fitted to achieve the reputation for which he pants. What are his prospects ? Can even the glowing pencil of enthusiasm add colour to the blank before him? ‘There are no situations in the state; there is No position in society to which hope can point, to cheer him in his laborious path. | If, indeed, he belong to one of our uni-. versities, there are some few chairs in his own Alma Mater to which he may at some distant day pretend; but these are not numerous; and whilst the salaries attached are seldom sufficient, for thesole supportof the individual, they are very rarely enough for that of a family. What then can he reply to the entreaties of his friends, to betake himself to some business in which per+ haps'they have power to assist him, or to choose some profes- sion in which his talents may produce for him their fair reward? If he have no fortune, the choice is taken away : he must give. up that line of Jife in which his habits of thought and his am- bition qualify him to succeed eminently, and he must choose the bar or some other profession, in which, amongst so many com- petitors, in spite of his great talents, he can be but moderately successful. The loss to:him is great, but to the country itis greater. ' We thus, by a destructive misapplication. of talent which our institutions create, exchange a pull reeset for but'a tolerable lawyer. If, on the other hand, he possess some sri fortune of his own; ‘and, intent on the glory of an immortal name, yet not blindly ignorant of the state of science, in this country, he resolves to make for:that aspiration a:saerifice the greater, be- National Encouragement of Science. 71 cause he is fully aware of its extent ;—if, so circumstanced, he give up a business or a profession on which he might have entered with advantage, with the hope that, when he shall have won a station high in the ranks of European science, he may a little augment his resources by some of those few em- ployments to which science leads ;—if he hope to obtain some situation, (at the Board of Longitude, * for example,) where he may be permitted to exercise the talents of a philosopher for the paltry remuneration of a clerk, he will find that other qualifications than knowledge and.a love of science are neces- sary for its attainment. He will also find that the high and. independent spirit, which usually dwells in the breast of those who are deeply versed in these pursuits, is ill adapted for such appointments ; and that even if successful, he must hear many things he disapproves, and raise no voice against them. Thus, then, it appears that scarcely any man can be expect- ed to pursue abstract science unless he possess a. private for- tune, and unless he can resolve to give up all intention of im- proving it. Yet, how few thus situated are likely to under- go the labour of the acquisition ; and if they do from some ir- resistible impulse, what inducement is there for them to devi- ate one step from those inquiries in which they find the great- est delight, into those which might be more immediately useful to the public ? General state of learned societies in England. , The progress of knowledge convinced the world that the system of the division of labour and of co-operation was as ap-~ plicable to science, as it had been found available for the im- provement of manufactures. . The want of competition in science produced effects similiar to those which the same cause _ gives birth to in the arts. The cultivators of botany were the first to feel that the range of knowledge embraced by. the Royal Society was too. comprehensive to ‘adarit of sufficient at- tention to their favourite subject, and they, established the Linnean Society. After many years, a new science arose, and the Geological Society was produced. At an another and more recent epoch, the friends of astronomy, urged by the * This body is now dissolved. 72 Mr Babbage's observations on the warits of their science, united to establish the Astronomical Society. Each of these bodies found, that the attention de- voted to their science by the parent establishment was in- sufficient for their wants, and each in succession experienced from the Royal Society the most determined opposition. Instituted by the most enlightened philosophers, solely for the promotion of the natural sciences, that learned body justly conceived that nothing could be more likely to render these young institutions permanently successful, than discouragement and opposition at their commencement. Finding their first attempts so eminently successful, they redoubled the severity of their persecution, and the result was commensurate with their exertions, and surpassed even their wildest anticipations. The Astronomical Society became in six years known and re- spected throughout Europe, not from the halo of reputation which the glory of its vigorous youth had thrown around the weakness of its declining years; but from the sterling merit of “ its unpretending deeds, from the sympathy it claimed and received from every practical astronomer, whose labours it re- lieved, and whose calculations it lightened. ” But the system which worked so well is now changed, nn the Zoological and Medico-Botanical Societies were established without opposition: perhaps, indeed, the total failure of the latter society is the best proof of the wisdom which guided the councils of the Royal. At present, the various societies exist with no feelings of rivalry or hostility, each pursuing its se- parate objects, and all uniting in deploring with filial regret, the second childhood of their common parent, and the evil councils by which that sad event has been anticipated. It is the custom to attach certain letters to the names of those who belong to different societies, and these marks of ownership are by many considered the only valuable part of their purchase on entry. The following is a list of some of these societies. ‘The second column gives the as apres prices of the Wehaeite indicated in the third. National Encowragement of Science. 3 Fees on Admis- sion, including SOCIETIES. Composition _Appended Letters. for annual Payments. ‘ae DS Ge Royal Society ul : = 50° 00 F.R.S. Royal Society of Edinburgh 25 Oger SE RSE: Royal Academy of Dublin 26 5 0 M. R.T. A. Royal Society of Literature 36 15 0 F. R.S. Lit. Antiquarian st . a 50 8 0 Pee eR Linnean - 2 a - "36" 00 F.L.S. Geological a 2 : 34 13 0 F. G. S. Astronomical . g 3 ORG OO M.A. S. Zoological e as i! 26 5 0 F. Z.S. Royal Institution s 3 50 0 0 M. R. TI. Royal Asiatic é ws a Seale | dad | F.R. A. S. Horticultural i i 48 6 0 F.H.S. Medico-Botanical C a 1°? 6? 6 F.M.B.S Thus, those who are ambitious of scientific distinction, may, according to their fancy, render their name a kind of comet, carrying with it a tail of upwards of forty letters, at the aver- age cost of L. 10, 9s. 9d. per letter. Perhaps the reader will remark, that science cannot be de- clining in a country which supports so many institutions for its cultivation. It is indeed creditable to us, that the greater part of these societies are maintained by the voluntary contributions of their members. But, unless the inquiries which have re- cently taken place in some of them should rectify the system - of management by which several have been oppressed, it is not difficult to predict that their duration will be short. Full publicity, printed statements of accounts, and occasional discus- sions and inquiries at general meetings, are the only safe- guards; and adue degree of vigilance should be exercised on those who discourage these principles. Of the Royal Society, I shall speak in a succeeding page; and I regret to add, that I might have said more. My object is to amend it; but, “ The Royal Society of Edinburgh now requires, for composition in lieu of annual contributions, a sum dependent on the value of the life of the member. 74 Mr Babbage’s observations on the like all deeply-rooted complaints, the operation which alone can contribute to its cure, is necessarily painful. Had the words of remonstrance or reproof found utterance through other channels, I had gladly been silent, content to support by my vote the reasonings of the friends of science and of the Society. But this:has not been the case, and after frustrated efforts to introduce improvements, I shall now endeavour, by the force of plain, but perhaps painful truths, to direct public opinion in calling for such a reform, as shall rescue the Royal Society from contempt in our own country, from ridicule in others. On the next five societies in the list, I shall offer no remarks. Of the Geological, I shall say a few words. It possesses all the freshness, the vigour, and the ardour of youth in the pur- suit of a youthful science, and has succeeded in a most diffi- cult experiment, that of having an oral discussion on the sub- ject of each paper read -at its meetings. To say of these dis- cussions, that they are very entertaining, is the least part of the praise which isdue tothem. They are generally very in- structive, and sometimes bring together isolated facts in the science which, though insignificant when separate, mutually il- lustrate each other, and ultimately lead to important conclusions. The continuance of these discussions evidently depends on the taste, the temper, and the good sense of the speakers: 'The things to be avoided are chiefly verbal criticisms—praise of each other beyond its reasonable limits, and contest for victory. This latter is, perhaps, the most important of the three, both for the interests of the society and of truth. With regard to the published volumes of their Transactions, it may be remark- ed, that if members were in the habit of communicating their papers to the Society in a more finished state, it would be at- tended with several advantages ; amongst others, with that of lightening the heavy duties of the officers, which are perhaps more laborious in this Society than in most others. ‘To court publicity in their accounts and proceedings, and to endeavour to represent all the feelings of the Society in the Council, and to avoid permanent Presidents, is a recommendation not ‘pe- culiarly addressed to this Society, but would contribute to the well-being of all. Of the Astronomical Society, which, from the nature of i its 4 | National Encouragement of Science. 15 pursuits, ‘could. scarcely admit.of the discussions similar to - those of the Geological, I shall merely observe, that I know of _no secret which has caused its great success, unless it be at- tention to the maxims which have just been stated. On the Zoological, Society, which affords much rational amusement to the public, a few hints may at present suffice. The largeness of its income is a frightful consideration. It is too tempting as the subject for jobs, and it is too fluctuating and uncertain in its amount, not to render embarrassment in the affairs of the Society a circumstance likely to occur, with- out the greatest circumspection. It is most probable, from the very recent formation of this Institution, that its Officers and Council are at present all that its best friends could wish; but it is still right to mention, that in such a Society, itis es- sentially necessary to have men of business on the Council, as well as persons possessing extensive knowledge of its pursuits, It.is more dangerous in such a Society than in any other, to pay compliments, by placing gentlemen on the Council who have not the qualifications which are requisite; a frequent change in the members of the Council is desirable, in order to find out who are the most regular attendants, and most quali- fied to conduct its business. Publicity in its accounts and pro- ceedings is, from the magnitude of its funds, more essential to the Zoological than to any other society ; and it is rather a fear- ful omen, that a check was attempted to be given to such in- quiries at the last anniversary meeting. If it is to be a scien- tifie body, the friends of science should not for an instant tole- rate such attempts. | It frequently happens, that gentlemen take an active part in more than one scientific society: in that case, it may be useful to derive instruction as to their merits, by observing the success of their measures in other societies. The Asiatic Society has, amongst other benefits, caused many valuable works to be translated, which could not have otherwise been published. The Horticultural Society has been ridden almost to death, and is now rousing itself; but its constitution seems to Have been somewhat impaired. ‘There are hopes of its purgation, and ultimate restoration, notwithstanding a debt of L. 19,000, a Prof. Zantedeschi on the variations of which the Committee of Inquiry have ascertained to exist, This, after all, will not be without its advantage to science, if it puts a stop to howse-lists, named by one or two persons,—to making complimentary councillors,—and to auditing the ac- counts without examining every item, or to —— even hes form altogether. The Medico-Botanical Society suddenly claimed the atten- tion of the public; its pretensions were great—its assurance unbounded. It speedily became distinguished, not by its pubs lications or discoveries, but by the number of princes it enroll- ed in its list. It is needless now to expose the extent of its short-lived quackery; but the evil deeds of that institution will long remain in the impression, they have contributed to confirm throughout Europe, of the character of our scientific _ establishments. It would be at once a judicious and a digni« fied course, if those lovers of science who have been so griev- ously deceived in this Society, were to enrol upon the latest page of its history its highest claim to public approbation, and by signing its dissolution, offer the only atonement in their power to the insulted science of their country. As with a sin- gular inversion of principle, the society contrived to render ex- pulsion * the highest honowr it could confer ; so it remains for it to exemplify, dn swicide, the sublimest virtue of which it is capable. Ant. VIII.—Eaperiments on the variations to which Mag- nets are incident when exposed to the Solar Rays. By Pro- fessor F. ZANTEDESCHI.T Since the experiments of Dr Hook and Dr Robison, it has been well known to natural philosophers, that red hot bars of iron placed at a suitable inclination in the plane of the magnetic meridian acquire a certain degree of magnetic vir-, * They expelled from amongst them a gentleman, of whom it is but slight praise to say, that he is the first and most philosophical botanist of our own country, and who is admired abroad as he is respected at home. The circumstance. which surprised the world was not his exit from, but his previous entrance into that Society. + Translated from the ssaiiaaar Universelle, November 1829, p- 193. Magnets exposed to the Solar Rays. ua tue, particularly according to Professor Barlocci, (Giornale Arcadico, T, 122, 1829, p. 145,) when they are in the vicini- ty of other magnets. We know also from the experiments of Professor Configliacchi, ( Giornale di Pavia, 1813, T. vi.) and MM. Fusinieri, Barlow, and several others, that metallic rods partially heated excite a particular influence in magnetic needles freely suspended ; and, finally, the delicate experi- ments of M. Kupffer, and other able natural philosophers, have shown that the intensity of magnetic action is in the di- rect ratio of the increase of the temperature of the magnet. Hence it follows that caloric concurs in putting electricity in- to motion, in developing magnetism under certain favourable circumstances, and in weakening it in others, in a manner ana- logous to what we observe in thermo-electric crystals, as the Jast experiments of Mr Ritchie have shown. But none of the philosophers that I know of has directed his attention to the influence which the solar rays may exercise in the pro- duction of electro-magnetic phenomena. Since the experiments of Professor Morichini, Professor Baumgartner has observed, that iron wires polished on a part of their length are magnetized by undecomposed solar light, exhibiting a north pole on the part which is polished. The results, however, obtained by Professor Barlocci, and by Mr Christie, (Phil. Trans. 1828, P. 2, p. $79,) have indu- ced me to complete an inquiry which I had undertaken some time before the Memoirs of these natural philosophers were known to me, and the sole purpose of which is to ascertain the variations to which magnets are incident under the influence of solar light. Hence it will be seen that I do not design to treat of the action of decomposed light, a subject on which the opinion of Professor Morichini, confirmed by the experiments of Mrs Somerville and those made by myself (Bibl. Univers. May 1829, p. 152,) appears sufficiently established. ‘The observations made at Paris by Cassini in 1792 on the diurnal changes in the variation of magnetic needles, those made by Watt and Christie, and many others which it is un- necessary to mention, demonstrate the influence of undecom- posed solar light upon all bodies, and in a less degree on those which are not sensibly magnetic. But these’ experiments, : 78 Prof. Zantedeschi on the variations of while they prove the existence of a powerful action of light’ upon terrestrial bodies, do not permit. us to. see the mode in. which the solar light acts in magnetic phenomena. I ought’ here to remark, that about the end of 1825, I had discovered that iron needles, deprived of all sensible magnetism, and. sus~ pended under a bell glass by a very fine fibre from the cocoon: of the silk worm, and having one of their extremities exposed: to the light of the sun concentrated by a lens, did not delay’ withdrawing itself from the action of the sun, and turning that extremity to the north in the plane of the magnetic meridian $' but this fact was discovered and published before me by other. natural philosophers ; and particular circumstances prevented me from resuming this subject before last year. It is true that my principal researches had for their object the action of the solar spectrum, nevertheless I remarked, that needles ‘of. iron, which did not possess any sensible magnetism, acquired’ a feeble polarity, when one of their extremities was placed for’ some time in compound light. But, satisfied with this first ob-’ servation, I abandoned the inquiry, and did not resume’it till the beginning of April in the present year. As it is in a great. measure the same as that of Professor Barlocci and Mr Chris- tie, I ought first to describe the results of these two natural philosophers, who have anticipated me by the publication of their labours, satisfied in. having followed the same route ch out being acquainted with their discoveries. | Doo Professor Barlocci discovered that an armed natural Leap stone, which could carry a weight of 14 Roman pounds, (a Ro- man Jb. = 339.179 grammes,) exhibited after three hours’ ex~ posure to the strong light of the sun, an increase of energy’ equivalent to two ounces or one-sixth of a pound, and at the end of twenty-four hours the force of the loadstone’ was al- most doubled. A second loadstone of nearly the same strength’ having been put into a dark place, whose temperature was equal to that of the solar rays, did not exhibit any apprecia- ble increase of strength. Another experiment was made with a stronger magnet, which carried five pounds, five ounces, and: two deniers. . This magnet having been exposed to the light im: a cloudy day, in which the atmosphere was charged with hu- midity, and when it even snowed, no sensible increase of ee Magnets exposed to the Solar Rays. 79 strength was perceived ; while in the two following days, dur- ing which the sky was perfectly clear, its strength increased more than double. A more lengthened exposure of the load- stone to the solar light did not produce a greater effect. My own experiments made with every possible care confirm- ed these results. An artificial horse-shoe loadstone, which car- ried 13! ounces, after exposure to the sun for three days, car- ried 3} ounces more ; and, by continuing its exposure, its power increased till it became 31 ounces. _ It was not pussible to obtain greater strength. I-could not observe any sensible modification by a dry and cloudy day. I obtained analogous results with natural loadstones of different degrees of strength. I was now desirous of ascertaining if oxidation had any influ- ence analogous to that which I had observed in my experi- ments on the violet ray. Experiment proved, that, whilst by exposure to the sun, the strength increased in oxidated mag- nets, it diminished in those which are not so, but that this di- minution became almost insensible when the loadstone was polished so as to reflect light like a mirror. A loadstone in- deed, not oxidated, which carried eight ounces, being exposed for three hours to solar light, lost 2} ounces of its strength, whilst another oxidated loadstone similarly exposed gained as much, and even more strength ; but having polished the first like a mirror, I could not observe any perceptible variation, though its exposure to the sun was greatly prolonged. Since these experiments, which I repeated several times dur- ing the most brilliant days of April and May, I have changed my method of operating. I cause the solar light to fall concentrated by means of a lens, sometimes on one pole and sometimes on the other, beginning always on the north pole; and I am convinced that the choice of one pole in place of another was not a mat- ter of indifference. A loadstone, whether oxidated or not, whose: north pole is exposed to the sun, acquires strength ; if it is its south pole it loses strength. I have also discovered by ex~ periments made successively with different loadstones, that the augmentation of force acquired in the first case is less than the loss sustained in the second, and that the variations are more considerable in oxidated loadstones than in those which are not so. In more than 60 experiments indeed, it was from 1 to 2 80 Prof, Zantedeschi on the variations of and to 3% ounces, whilst the diminution in the corresponding case was from 3} to 5, and to 5} ounces, ein I have observed oxidated magnets acquire an energy duabhe of that which they had previously, which did not _ place with those whose surface was clear. Finally, I satisfied myself that cooling was a cireumstance favourable to the increase of magnetism. The loss of force, ins deed, which a magnet sustained whose south pole had been exposed to the sun, diminished when this exposure ceased, The increase obtained by the one whose north pole had’ been exposed, augmented on the contrary, in the same circumstances. I ought not to conceal that I often encountered anomalies, of which I could not discover the cause. Magnets are a kind of Proteuses, which transform themselves under the eyes even of the most attentive observer. I trust, therefore, that philoso- phers who repeat my experiments, will not accuse me of inae- - curacy on this subject. A fact which surprised me extremely, and which I should still have doubted, if I had not reproduced it several times before intelligent persons, is, that in days when the sun was slightly covered with an unequal veil, the south pole submitted to thé action of concentrated solar light manifested an increase of energy, whilst the north pole exhibited a diminution. It should be remarked, that in the first experiment, it was the south pole which I first submitted to the concentrated light. On the day following, which was the 4th June, I resumed my experi- ments at 2" p,m. Till half-past four, the space of time during which the sun’s light was very clear, I exposed alternately the poles of several magnets, and I saw reproduced. the effects which I have above described, viz. an increase of strength by. the exposure of the north pole, and a diminution by that of the south pole, even when I began by exposing this last pole. But after half-past four, the sun being covered with a very thin veil, the same experiments continued presented inverse phe- nomend, that is the same as those which I observed the day. before, duriig which the sun was slightly covered. The same experiments reported. by other persons have clearly demonstra- ted that these were constantly the phenomena, I freely con- fess that I was astonished at this contrast, and I could not Magnets exposed to the Solar Rays. 8 assign any cause for it but by supposing that light presented a negative polarity, the inverse of that of the strata of vapours which float in the atmosphere, such as is observed in the or- dinary phenomena of polarisation, according to the fine dis- coveries of Brewster and Arago upon paraselenze. * It will perhaps be objected, that in all these experiments the action of caloric is combined with that of light, so that the final effect is due either to the isolated influence of one of these agents or to the combined influence of both. I feel all the force of this objection, but, as I have said above, caloric acts in general as a cause which diminishes the magnetic intensity. Besides, I have recurred to direct experiments which prove that, in the phenomena described, it has not acted otherwise. If we heat a piece of brick, but not so as to become luminous, and if we bring it near one of the poles of a magnet, we shall find that this magnet will no longer carry the same weight as before. The phenomenon in question, therefore, can only be ascribed to light. ) Hitherto my manner of experimenting is that of Professor Barlocci, partly modified. That which I am going to describe is imitated from Mr Christie. This able natural philosopher informs us that direct solar light, as well as a plate of copper placed in the neighbourhood, diminishes the arcs of oscillation of a moveable magnetic needle. I tried at several times. to repeat the experiments of the English natural philosopher with needles three inches long, but I could not obtain satis- factory results, as was seen by Professor Confighiacchi, who was so kind as to assist me in this inquiry. In consequence of this I had a needle made a Paris foot in length, and having repeated the experiment of Christie in very clear days, I could no longer doubt the accuracy of his-re- sults. In the shade, indeed, when this needle was drawn from its position of equilibrium through an arch of 90°, it. perform- ed in 30” four oscillations, the last of which had a _ semi- amplitude of 70°. When exposed to the solar rays, it per- formed in the same time, and under the same circumstances, four oscillations, the last of which had only a semi-amplitude of 60°. I obtained more marked effects by causing the needle * We do not understand what the author means by this reference-—Ep, NEW SERIES. VOL. III. NO. t. JULY 1830. nw 82 Dr Hibbert on Fossil remains in the Velay. ‘ to perform 6, 8, 12, and 14 oscillations. I next tried if I could discover the law which I had formerly observed rela- tive to the poles, that is, if, by exposing to the sun the north pole of the needle, I should obtain a greater number of oscil- lations and a less amplitude than by exposing the south pole. A series of experiments, repeated more than thirty times, has demonstrated to me the existence of this law. I consider it superfluous to insert the three or four tables which contain my | results. I shall merely observe, for those who desire to re peat these experiments, that when I expose to the sun the north pole, the semi-amplitude of the last oscillation has 6° less than that of the first, while, by exposing the south pele, this last oscillation became greater than the first. _ It will be sufficient to add, that in days slightly cloudy the results were inverse, as happened in the other experiments,, and that the diminution of temperature augmented the inten- sity of the directive force. ‘hese experiments, though very delicate, have inspired me with great confidence, both on account of the regularity of the effects obtained, and on account of the manner in which they were made. I might still quote other facts which struck me in the course of my observations in June, and which tend to confirm what has been said above on the inverse action of heat and light; but as I propose to treat the subject at greater length, I defer their publication to another opportunity. Pavia, July 4, 1829. Arr. 1X.—IJnquiry into the circumstances under which the Remains of some Fossil Animals were accumulated in the volcanic soil of the Velay, in France. By S. Hiner, M.D., F. R.S. E., &c. &c. Communicated by the Author. Iw the memoir, by M. Bertrand de Doue, of which a trans- lation was given in the last number of this Journal, concerning the bones of the Hyena. and other animals which were imbed- © ded in the tufa of Saint-Privat, an allusion was made by him to another discovery by M. Felix Robert, an intelligent natural- ist of Le Puy, of the fossil remains of animals of the Bos genus, Dr Hibbert on Fossil remains in the Velay. 83 and of Cervi of a very large size, which were found near a basal- tic plateau to the north of Polignac ; the accumulation of which, according to the writer quoted, is due to circumstances very dif- ferent from those which were the subject of his memoir. A very satisfactory inquiry into the circumstances under which these animals were discovered may be expected from the very able naturalists of this vicinity. The site was pointed out to me by M. Robert, and in giving the result of my own examina- tion, I must add, that the accumulation of these remains is most difficult to be explained, except in connection with the more general geological history of the Velay, of which I shall attempt a very faint sketch ;—professing at the same time my | acknowledgment for the assistance which I have received in drawing it up; from the masterly treatise on the a pa of this province by M. Bertrand de Doue. The lowest exposed rocks of the district of the Velay consist of granite; which is associated in a few places with such primary strata as gneiss or mica slate. The granite is, m the vicinity of Le Puy, surmounted by secondary strata, which are probably those of the quader sandstein. Long after the period of this deposit the vallies of this portion of France became subject to a new change. ‘They exhibited a series of lakes flowing ‘the one after the other along the actual course of the Loire, of which the basin of Le Puy was the most elevated. The effect of this was a tertiary calcareous deposit, comprising sandy clays, pot- ter’s clay, marly and gypseous beds, &c.; and as new races of vegetables and animals were then called into existence, remains of gramineous and other vegetables have been discovered in the deposit, along with such fossil shells as Lymnez, Cyclostome, Bulimi, Planorbes, and Gyrogonites, and such large mammi- ferous animals as the Paleotherium and the Anthracotherium. That-the lake of Le Puy existed long, is evident by the thickness of its deposit, which attains the depth of near four hun- dred and fifty feet; but that its confines continued during the whole time to be lined with forests which gave shelter to verte- bral animals, does not appear. Some great catastrophe seems to have occurred, which, at least in the district of the Velay, was incompatible with the existence of organic beings. This is shown in the remarkable system of beds discoverable at the ra-. 84 Dr Hibbert on Fossil remains in the Velay: vine Des Brus, near..Le Puy; at this place there are at least twelve beds of calcareous and argillaceous marls, severally vary- ing from about two inches and a half to ten feet in thickness, which exhibit alternations, _ several. times repeated, of . beds with fresh water. shells of different kinds, and with beds that show extremely ;few or none of these remains ; while the whole of this upper deposit exhibits the absence, or at least the ex- treme rarity of remains or impressions of the vegetable kingdom. —From this appearance M. Bertrand de Doue has made many. important deductions. cet Such is a feeble sketch of the geological history of the Velay, which immediately preceded a new order and system of nature; which new order was first characterized by a cessation of the cause, whatever it was, that induced the calcareous and argilla- ceous fresh water deposit, which had before subsisted. . When the surface of the earth had become tranquillized, a new vegetable and animal creation appears to have taken place, to supply the deficiency which had resulted from prior changes. The first vegetable deposit which ensued, is perhaps one of the most interesting which is to be found in the whole course of our geological researches. This is the Brown Coal deposit of the German geologists, which, as a formation, is the best studied in the neighbourhood of the Lower Rhine. It is, how- ever, sufficiently well marked in the Velay, where it exhibits, as in other districts of Europe, one common character. This deposit, in its relations, intimates the existence of sila forests as were calculated for, a state of the country, wheresthe watersof its ancient lakes were in a slow and gradual state of drain- age. In the time when the brown coal of the Velay was form- ed, the waters of the expansions of the Loire had commenced the process of drainage; they had readily deepened for them- selves a passage through the soft calcareous marl, leaving on the sides of the basin of Le Puy much wet ground. In many conveni- ent declivities, therefore, such trees as were calculated for a marshy state of the soil. rose into existence, such as the birch, the willow or the alder, and along with them fresh water fish; frogs, lizards, and numerous insects. ‘These are accordingly the organic remains indicative of the brown coal. formation, which _we trace in many parts of Europe; and as the marshy state of —_—- - Dr Hibbert on Fossil remuins in the Velay. 85 the country, which it intimates, was calculated for’ ‘particular races of animals, we accordingly find, as it can be distinctly shown on the banks of the Rhine, that several mammiferous tribes, some of which are now extinct, date their existence from the commencement of this interesting formation. During the time that the early forests of this new state’ of dur globe subsisted, of which this and other similar deposits in Eu- rope give so decided an intimation, the process of degradation was rapidly’ proceeding; and as the debris of these marshy fo- rests, along with the disintegrated materials of the rocks of the Velay, would be carried into low levels, we accordingly find in the deposits of the brown coal formation, various alternations of earthy and vegetable matter. Some of these ancient forests ap- pear in time to have been obliterated; owing, probably, to the too rapid progress of disintegration which was induced, by which new lands were rapidly formed. Thus, at Roche-Lambert, near St Paulien, alternations of lignite and earthy deposits are sur- mounted by a bed of whitish micaceous sand about fifty feet thick, mixed with clay and attrited fragments of quartz and felspar ; and at Aubepin the deposit is terminated by a bed, a few in- ches thick, of quartzose sand, coloured yellow by the hydrate of iron. Such forests, however, as continued to exist, were the haunts of animals‘of the Bos kind, and of various species of Cer- vi, some of a large size, and (as recent discoveries have proved) of the Rhinoceros leptorhinus of Italy, as well as of the Hyzena spelea. Remains of the human race have not yet been found in the Velay ; though such a discovery, seeing that it has been proved in the south of France that man was a contemporary of different extinct animals, is by no means improbable. The forests and marshes of France had for some time been peopled with various races of animals, when convulsions appear to have shaken the solid rocks of Europe to their very founda- tion. ‘The Velay partook deeply of the commotion ; a system of volcanoes, tremendous’ in its nature and effects, bursting forth from the high lands from which the Loire takes its rise, and extending, for the most part; in a-direction east of the river along the limits of the fresh water basin of Le Puy. Some few eruptions took place from beneath the fresh water de_ posit itself ‘The volcanic materials which were ejected con- 86 Dr Hibbert on Fossil remains in the Velay. sisted of trachytic felspar and of basalt, the latter substance be- ing the most abundant. Successive torrents of lava, ejections of scorize, and deposits of tufa, thus spread themselves over the country, filling up declivities, and, in coating the surface of the calcareous deposit of a preceding state of the earth, protected much of it from the further process of disintegration. | _ But extensive as these eruptions were, we do not find that they put a stop to the vegetation of the country.. ‘Thus, at Collet, Ronzal and other sites, strata. of the brown coal deposit, consisting of black carboniferous clays containing vegetable re- mains and accompanied with ferruginous sands, alternate with rolled masses of trachyte, phonolite, basalt, or volcanic cinders. The remains also of many large animals which have been dis- covered appear in an intermediary period of these convul- sions, under circumstances which demand much explanation in order to be understood. It would appear that in an advanced epoch of these volcanic eruptions, after the waters of the Loire, in hollowing out a course for themselves through the tertiary strata, had sunk nearly to their present level, that the stream was dammed up at the narrow gorge of Chamelieres by an eruption of an im- mense dike or mass of phonolitic lava; similar impediments to the outlet and drainage of the vallies occurring even in. other sites, though in a less degree. By the inundation which thus took place, two expansions or lakes were formed, into which volcanic cinders and scorie, fragments of trachyte and basalt, as well as the disintegrated masses of primary rocks were washed; which were again mingled with the different products of the calcareous deposits which had previously occupied the basin. And hence, nothing can well exceed the variety of earthy mix- tures which were thereby induced. In some places the mecha- nical force of the water and calcareous infiltrations’ has formed the deposit, for a considerable space, into a compact brecciated mass, rivalling the hardness and massiveness of solid lava; in_ other spots, by the prevalence of finer products, a regular stra- tification has ensued ;—elsewhere, by the presence of iron in different states of oxidation acting on the finer materials, of scorize or cinders, a mass has been induced, beautifully variega- ted in colour, to which the name has been given of ribboned ! Dr Hibbert on Fossil remains in the Velay. 87 breccia. Occasionally, where there has been no play of infiltra- tion, we find the mass to be uncemented, loose, and earthy. A last variety consists of marly or argillaceous fragments conjoined and more or less indurated, which are varied by the presence of rolled or angular fragments of granite, small masses of olivine, remains of vegetables, or geodes of the hydrate of iron. But other effects necessarily resulted from the damming up of the course of the Loire. The waters, which, by the filling up of their beds, were constrained to maintain a higher level, had this level agam so much increased by the volcanic products washed into them as to fill the high lateral vallies.. During this general overflow, therefore, we may turn our attention to the site of a lateral valley situated between St Paulien and the castle of Polignac, the tertiary deposit of which is surmounted by a mass of volcanic debris, consisting of large fragments of basalt mixed with scorie and ashes which were washed into it from an extensive basaltic plateau. The. larger fragments, some of which are several tons weight, show, in many places, by the rounding of their angles, marks of their having been ex- posed to the abrading action of fierce torrents; they are also frequently united by a muddy and little coherent paste, consist- ing of clay and sand, the result of comminuted or decomposed materials. This stratum is indicative of the period when the adjoining volcanoes were in activity, and when, from the sud- den obstacles opposed to the discharge of the waters, deluges were in full force, being of sufficient activity to wash from the neigh- bouring volcanic plateau masses of an immense size, so as to form one chaotic mass. In process of time, however, when the Loire, which had attained the full height of its increased level, had forced for itself an emission by some new course, or had per- haps deepened for itself a passage through its old gorge, nature was more composed; which tranquil state is indicated by the superior strata, near Cussac, which surmount the mass of huge fragments, and which consist of the finer materials of sand and clay disposed in regular strata, and often so consolidated as to resemble a soft sandstone. During this last mentioned state of the site of Cussac, the banks of the lateral branch of the lake, which once filled the valley, and. which indicate a high level of waters, were evidently frequented by animals of the Bos ge- 88 Dr Hibbert on Fossil remains in the Velay. nus, as well as by stags of a gigantic size, the remains of which have been recently found imbedded.in the last mentioned strata. But although the evidence is irresistible that they pastured here during some short intervals when the volcanic focus was quiescent, the circumstances which led to their inhumation can only form the subject of conjecture, regarding which what I have to say will be brief. It is manifest, from the very large quantity of bones which the rains have annually washed out of this deposit of sand and clay, _ that a herd or more of graminiverous animals have been here _ entombed, some entire skeletons of which have been found by the industry of M. Felix Robert, on whose estate they occur. It is, therefore, by no means improbable, that these animals had met with some accidental fate; probably from the sudden or in- stantaneous rise of the lake above the level which it had as- sumed. This is a circumstance the most likely to happen from the continued activity of the volcanoes long after this period ; whence new impediments would be likely to occur, to prevent the discharge of the waters. Thus, it might arise from some outlet being again dammed up, or from the level of the lake being sud-__. denly elevated, owing to new ejected matters being added to ~ the former contents of its basin. Or, lastly, the animals might have met with a sudden fate independently of volcanic causes ; as by some land-slip causing a further stoppage, or filling up of the basin, and so inducing a new flood by which they were drowned. Any of these inferences are easily suggested by the geological circumstances that connect themselves with the in- humation of these animals ; while that of their being destroyed by an immense wave indicative of the general deluge, which in its frightful progress had swept before it immense fragments of rocks, and dispersed them over distant planes, is forbidden by the fact, that not a single stone or boulder has hitherto been found in the district of the Velay, which cannot be traced to © SRS heights. The remaining portion of the volcanic history of thie Velay, has been alluded to in the last number of this Jowrnal, in the description which was given of the circumstances under which the remains of the hyena and other animals were discovered. The river Allier runs for a distance of nine leagues, a course Dr Hibbert on Fossil remains in the Velay. 89 not very far from parallel with the Loire, and from the moun- tains of this intermediate space, numerous flows of lava issuing from volcanic mouths may be traced ; which, from their relations of superposition, and from the nature of the products ejected, have evidently belonged to races the most recent of the long pe- riod during which subterranean fires have ravaged the soil of the Velay. In this district, at the village of Saint-Privat, I recently discovered the bones of fossil animals imbedded in a volcanic tufa, and covered over by a subsequent flow of basaltic lava; while the excavations since conducted by M. Bertrand de Doue, to whom I pointed out the site, have showed, that the tufa had afforded burrows for hyenas, who had here retired with the spoils of the animals upon whose carcases they had fed. Either contemporary with the last mentioned volcanoes, or not long after them, it is probable that the district of the Velay became the abode of man. But for the verification of this sup- position, we must wait for such interesting discoveries of the bones of the human race being mingled with those of extinct animals, as have been made in the caves of the south of France. The last eruptions which lightened up the volcanic regions of France were probably in the district adjoining that of the Ve- lay, named the Viverais. Sidonius Apollinaris, who lived in the fifth century, has adverted to an eruption of his own time, as ** one in which the earthquakes demolished the walls of Vi- enne ; when the mountains opened and vomited forth torrents of inflamed materials; and when the wild beasts, driven from the woods by fire and terror, repaired into the town and made ex- tensive ravages.” Traces of this last eruption ought to be discovered. ‘They may, perhaps, be identified in a volcanic hill which I crossed between Thueys and Montpezat, where the flows of the lava show a freshness that is not to be exceeded by any of the vol- canoes of the continent, those of Italy excepted. To quote the words of a companion of my journey, “‘ waves of lava still ap- peared without a blade of grass upon ‘them, as if they had flow- ed down the hill not a week before, or as if they were scarcely cold.” , 90 Experimenis on, the Elastic force of Steam. , Art. X.—Account of Experiments on the Elastic force g Steam up to twenty-four Atmospheres, made by order of the Academy of Sciences of Paris. Tue French Government having resolved to submit. steam engines to examination, consulted, the Academy. of Sciences respecting the means which, without checking the developement of industry or the operations of commerce, might be most suitable to prevent those disastrous accidents which might arise from the explosion of steam boilers. This important question was examined by a special commis- sion, whose report, discussed and approved of by the Academy, was addressed to the Minister of the Interior. : Five months afterwards, on the 9th October 1823, there ap- peared a royal ordonnance which rendered obligatory the mea- sures proposed by the Academy; but it was quickly seen by the engineers, who were specially charged with the execution of this ordonnance, that the wishes of the government could only be fulfilled by executing a series of difficult and expensive experiments on the elasticity of steam at very considerable temperatures. ‘I'he government engaged the Academy to un- dertake these experiments; and a committee, consisting of MM. Prony, Arago, Ampere, Gerard and Dulong, was appointed to superintend the construction of the apparatus, and to exe- cute the experiments. : As similar experiments had never been made on sinetuatiaes ‘above eight atmospheres, the committee resolved to. extend them to above twenty; and in performing this most arduous task, they have evinced the greatest ingenuity and practical skill in the construction of the apparatus, and the greatest ad- dress in conducting the experiments.. The results which were thus obtained, cannot fail to be considered as one of the most valuable presents which science +has for a long time conferred on the arts of life; and as likely to prove one of the greatest blessings to humanity. . It is a reflection on England and on her successive governments, that such experiments have not been long ago made under their direction ;— it is a reflection on our publicinstitutions, which ought inmatters of science toadvise ‘ Experiments on the Elastic force of Steam. 91 and stimulate the government ;—it is a reflection on: the charac- teristic benevolence of our countrymen, that means should not have been taken to avert the tremendous calamities of explo- sions by steam. But in proportion as it was the duty of Eng- land, where every thing but intellectual labour is carried on by steam, to have originated and completed such an inquiry ; in the same proportion is it honourable to the French Govern- ment, to the Academy of Sciences, and to the eminent committee whom they appointed, to have achieved so important a work.* Our limits will not permit us to give any-account of the appa- ratus employed by the committee. We shall state, however, the method of measuring the temperature of the steam, and any other details of particular interest. ‘ The exact measure of the temperature, as the report states, presented some difficulty. The thermometer ought not to be exposed directly to the pressure of the steam ; for even though it might be able to support it without being broken, it would have been necessary to take into account the effects of the com- pression, the estimation of which would have been sufficiently embarrassing. In order to obviate this inconvenience, there were introduced into the boiler two gun-barrels closed at one end, and drawn to a point, to afford a resistance necessary to prevent their being crushed during the experiment. The one descended nearly to the bottom of the boiler, and the other did not go farther than the one-fourth of its depth. The thermometers were placed in the interior of these cylin- ders filled with mercury, the shortest being used to give the temperature of the steam, and the longest the temperature of the water. ‘This method, the only one which is practicable in - experiments of this kind, would have been very defective, if it had not been accompanied with convenient means of rendering the variations of temperature very slow. ‘This is one of the reasous which induced us to give to the boiler and furnace greater dimensions than would otherwise have been necessary ; for we are satisfied from several trials, that near the maximum, the smallest variations in the elasticity of the steam are accom- * Such of our readers as have perused the able paper by Mr Babbageon the Decline of Science in England, printed in this number, will find in these details a most striking proof of his sentiments. oa 92 Experiments on the Elastic force of Steam. panied with. corresponding variations in the indication of the thermometers. 93 Temperature by Temperature by Elasticities in Llasticitiesin Elasticities in small Cent. ther- - large Cent. ther- metres of | atmospheres of metres of mer- mometer. - mometer. mercury. 0.76 metres... cury at 0°. 122 °97 123.° 7 1.62916. 2. 14 1. 62916 132. 58 132. 82 2.1823 2. 87 2. 1767 132. 64 133. 3 2.18726 2. 88 2. 1816 137. 70 138. 3 2.54456 3. 348 2.5386 149. 54 149. 7 3.484 4. 584 3.4759 - 151. 87 151. 9 3.69536 4. 86 3. 6868 153. 64 153. 7 3.8905 5.12 3. 881 163. 00 163. 4 4.9489 6. 51 4. 9383 168. 40 168. 3 5.61754 7. 391 5 6054 169. 57 169. 4 5.78624 7. 613 5. 7737 171. 88 172. 34 6.167 8. 114 6.151 180. 71 180. 7 7.51874 9. 893 7. 5001 183. 70 183. 7 8.0562 10. 6 8. 0352 186. 80 187. 1 8.72218 ll. 48 8. 6995 188. 30 188. 5 8.8631 11. 66 8. 840 193. 70 193. 7 10.0254 13. 19 9. 9989 198: 55 198. 5 11.047 14. 53 11. 019. 202. 00 201.75 11.8929 15. 65 11. 862 203. 40 204. 17 12.321 16. 21 ~ 12. 2903 206. 17 206. 10 13.0211 17.13 12. 9872. 206. 40 206. 8 13.0955 17. 23 13. 061. 207. 09 207. 4 13.167 17.3 13. 1276 208. 45 208. 9 13.7204 18. 05 13. 6843 209. 10 209. 13 13.8049 18. 16 13. 769 | 210. 47 210. 6 14.1001 18. 55 14. 0634 215. 07 215. 3 15.5407 20. 44 15. 4995 217. 23 217. 5 16.1948 21. 31 16. 1528. 218. 3 218. 4 16.4226. 21. 6 16. 3816 220, 4 220. 8 17.2248 22. 66 17. 1826 293. 88 224. 15 18.2343 23. 994 is. 1994 The committee next proceed to notice the experiments pre- viously made on the elasticity of steam, and the formule given to represent them. The experiments thus noticed are those of Southern, Taylor, and Ure, none of which were carried beyond eight atmospheres, and those of Arzberger, * Professor in the. Polytechnic Institution of Vienna. In the experiments of the German Professor, the elasticity was measured by the effect necessary to prevent the rising of a valve furnished with a lever. He appears to have carried his experiments so high as twenty * Jahrhiicher des k. k. polytechnisches Institutes in Wien, T. 1, p. 144, 1819. Polytechnisches Journal von Dingler, T. 12, p. 17 ern des Sciences Technologiques, ‘TV. 1, p. 123. Experiments on the Elastic force of Steam. 93 atmospheres, the temperature corresponding to which was 222° cent., which it will be seen corresponds to twenty-three atmospheres in the present experiments. This difference seems to have arisen from the thermometer having been exposed to the pressure of the steam, and having thence experienced a diminution of capacity. The formule noticed by the committee are those of Prony, Laplace, Biot, Ivory, Roche, Auguste, 'Tregaskis, (see this Journal, No. xix. p. 68.) Crichton, weep tp st mene and ‘Coriolis. The formula of Prony, or 2 = pw, 2.7 + 0,9 + Bu, gi, im which zis the elastic force and @ the temperature of the steam, was contrived to represent Bettancourt’s observations, but the length of the calculations necessary to determine the six con- stants yu, g, &c. renders it tedious to use this method of interpo- lation. M. Laplace, following the approximative law of Dalton, viz. that the elasticities of the steam increase nearly in geometrical progression, when the temperatures are in arithmetical ‘pro-. gression, represents the elastic force by an exponential, whose exponent is developed in a parabolic serics. The two first terms appeared to him sufficient, but M. Biot proved the ne- cessity of taking a third. (See T'raité de Phys.T. i. p. 277,350.) This kind of expression the committee found to be one of those which deviates most from observation, and five or six terms of the series would now be necessary, which would make the calculation interminable. ‘The formula of Ivory, which is of the same nature, though the coefficients are obtained by another process, has the same inconvenience. At the highest temperature of the experiments of the committee, it gives an elastic force more than double of that observed. M. Roche, professor of Mathematics in the Marine School of Artillery at Toulon, sent to the Academy in the beginning of 1828, a memoir on the law of the elastic forces of steam. It is not merely an interpolation useful to the arts which the author proposes to establish. He regards his formula asa physical law, deduced by calculation from the most: general principles of the theory of vapours.. The committee regard . 94. Experiments on the Elastic force of Stéam. this theory as not well founded, but they find that the formu: la is one of those which agree best with observation,’ being ini error only one degree for twenty-four atmospheres, and a tenth of a degree only for about two atmospheres. vet of Nearly about the same time, M. Auguste of Berlin; pub: lished a formula so far like the preceding that the elastic force is represented ‘by an exponential, whose fractional expotient contains the temperature both in its numerator and denomi- (@ +n)t 7 \% nator. ‘This formula is e= a ( ) n(w +1) where eis thevleae ticity in metres of mercury, @ the elasticity of the vapour at 0° cent. 6 = 0.76, nm = 100, » = 266 §, and ¢ the temperature centigrade, setting out from that of melting ice. . M. Auguste establishes this formula, by considerations different from, those of M. Roche, and the temperatures are reckoned on the alr thermometer. The formula gives the temperature for twenty- four atmospheres, 214°.37.. Observation gives 224°.2:on the mercurial, or 220°.33 on the air thermometer. The differ. ence is then about 6°, or if we calculate the elasticity for the temperature of 220° or the air thermometer, we shall find an excess of more than two metres of mercury. The formula originally proposed by M. T regaskis | in the Edinburgh Journal of Science, is not found to agree with ob- servation at high temperatures. The dieintions amounts. to about 2°. Almost. all the other formulee hitherto rent rest on. the same principles, and differ only in the constants which enter into their composition. Dr Young appears to haye been the first who represented the elasticities by a certain power of. the ‘temperature, augmented by a constant number. He adopted the exponent 7. Creighton took 6 to represent Ure’s ex- periments, Southern took 5.13, and Tredgold adopted the exponent of Creighton, changing the coefficient ; and. lastly, M. Coriolis adopts 5,855, deduced from Dalton’s experiments below 100.° ‘This formula. differs very little from that which we have employed. . It agrees well with the extreme observa- tions, and differs, only two or three tenths of a degree : for 1 + 0.01878% 5.355 intermediate ones. - The formula is é = ( me) . Experiments on the Elastic force of Steam. 95 where e expresses the elasticity in atmospheres of 0™. 76 and ¢ the temperature.in cent, degrees setting out from 0°. We prefer, however, the formula e = (1+ 0.7153 ¢)’ where e is the elasticity in atmospheres of 0™. 76, and ¢ the tempera- ture setting out from 100°, being taken positively above and negatively below 100, the interval of 100 being taken for uni- ty.. The only coefficient which enters into this formula was deduced from the highest term of our observations. . 7 We have placed in the following table the values given for the principal terms of the series, by the four formulz which deviate the least from experiment, and which are not too diffi- cult of calculation. Elasticity | “elasticity ; Temp. calc. in metres} in atmos: | Tempera- | Pempera- |Penrpera» {Tempera |’ formula of jof mercury] pheres of | ture ob- | ture calc. | ture cale. | ture cale. the Commit- | at 0° | Om. 76. | served. |fredgold. |De Roche.| Coriolis. tee. 1.62916} 2.14 123°.7 123°.54 | 123°.58 | 123°.45 |... 199°.97 2.1816 2.8705 | 133 .3 | 133 .54 | 133 .43| 133.341. 139.9 3.4759 4.5735 | 149 .7 150 .29 | 150 .23 | 150.3 149 .77 4.9383 6.4977 | 163 .4 164 .06.} 163 .9 164.1 (163 475 5.6054 7.3755 | 168 .5 169 .07 | 169 .09 | 169 .8 168.7 $.840° | 11.639: 188 5188 .44 | 188463 P1890! 188.6 | 413.061 _|/17.185..|, 206.8... 206.15 | 207 04 | 207.48]! 207).2 418.137 |17.285 | 207.4 | 206.3 | 206 .94| 207 .68| 207.5 / 14.0634 | 18.504 | 210.5 | 09'.55) 210.3 | 21106! S10 8 16.3816 | 21.555 | 218 4 216 .29) 218 .01} 218 .66 218) .5° 18.1894 | 23.934 | 224.15 | 222 .09 | 233 .4 | 224.0 |, 204.09 The following are the formule by which this table has been calculated. 1. Tredgol@s, t = 8d ¢/ f—i5, t being the temperature in centigrade degrees setting out from 0°, and “df the elasticity in centimetres of mercury. 1P (Log. picky 760) 2. De Roche's, = pl6s4 — 0.03 Lag: Ce Fe # being the temperature in centigrade degrees above 100°, and f the elas- ticity in millimetres of mercury. The coefficient. 0.1644: is deduced from the new observations of the committee.. §.355 Pap ae rane At) 3. Coriolis’s, t= Ta t being the temipetieure in centigrade degrees setting out from 0°, and f the elasticity in atmospheres of 0.76 metres. fee 96 Experiments on the Elastic force of Steam. | | 5y 4. The formula adopted by the Committee is t ately t being the temperature in centigrade degrees setting out from 100°, and taking for unity the interval of 100°, and f the elasticity in atmospheres of 0.'76 metres. By comparing the last five columns of this table, it will be seen, that, as far as three or four atmospheres, the three first of these columns represent the observations with sufficient fide- lity, but beyond this the fourth of these columns, adopted by the committee, is constantly nearer to the experimental results. The greatest difference is 0.°4, and in almost all the rest it is only 0.°1. A more considerable deviation which takes place in the two first terms is of little consequence in this part of the scale, so that the formula may be applied to the arts even in this inter- val. ‘Though by the nature of the experimental process which we employed, the errors ought to be proportionally greater for low pressures, it is not probable that the formula errs in de- fect from this cause, for it will be perceived that for smaller pressures than one atmosphere, the divergence increases more and more, in proportion as we descend lower. Hence it ap- pears that the employment of the formula ought to be limited to elasticities greater than one atmosphere. The formula of Tredgold may be used to 100°, or even to 140°. Having thus obtained a very simple formula, which agrees so perfectly with observation, we may employ it in calculating the table which forms the principal object of these researches ; and as the only coefficient which enters into it has been deter- mined from the last term of the series, we cannot doubt, from its coincidence with the preceding terms, that it may be ex- tended much farther without any notable error. We are per- suaded that at 50 atmospheres the error will not exceed a de- gree. The following table contains the temperatures calculated for pressures which increase by half atmospheres from one to eight, by-whole atmospheres from eight to twenty-four, where the observations end; and by five atmospheres, from twenty- five to fifty, supposing that the formula extends so far. 3 Experiments on the Elastic force of Steam. 97 Table ft the Elastic forces of Steam, and of the yc tga temperatures. neal FB lastiaisieiain Temperatures on Pressure on a Elasticities in metres ater the mercurial square centi- Atmospheres. $ centigrade ther- metre in Kilo- cury eee. mometer. grammes. 1 0.7600 100° 1.033 12 1.1400 112 .2 1.549 2 1.5200 121 .4 2.066 Qt 1.9000 128 .8 2.582” 5 2.280 135 .1 - ~ $.099 33 2.66. 140 .6 3.615 —- mn 3.04 145 .4 4.132 4a 3.42 149 .06 4.648 5 3.80 153 .08 5.165 51 4.18 156 .8 5.681 6 4.56 160 .2 6.198 63 4.94 ~. 163 .48 6.714 7 5.32 166 .5 7.231 7 5.70 169 .37 TAT 8 6.08 172 .1 8.264 9 6.84 177 .1 9.297 10 7.60 181 .6 10.33 11 8.36 186 .03 11.363 12 9.12 190 .0 12.396 13 9.88 193 .7 13.429 14 10.64 197.19 14.462 | 15 11.40 200 .48 15.495 16 12.16 203 .60 16.528 17 12.92 206 .57 17.561 18 13.68 209 .4 18.594 19 14.44 212 .1 19.627 20 15.20 214 .7 20.660 21 15.96 217 2 21.693 22 16.72 219 .6 22.°726 23 17.48 221 9 23.759 24 18.24 224 .2 24.792 The following numbers are calculated. | 25 19.00 226 .3 25.825 | NEW SERIES, VOL. III. NO. 1, JULY 1830. G 98 Prof. Agardh on Inscriptions in living Trees. 30 22.80 236.2" : 30990. 35 26.60 244 .B5 36.155 40 30.40 . 852 .55 41.320 45 © 84.20: 259.52 46.485 50 38.00 265 .89 51.650 — The temperatures which correspond to the tensions from one to four atmospheres inclusive, have been calculated by the formula of Tredgold, which in this part of the scale accords better than the others with our observations. —Abstract, from the Ann. de Chim. Jan. 1830. Arr. XIL—On Inscriptions in living Trees. By Dr C. A. Acanrpu, Professor of Economy and Botany at Lund. Translated from the Swedish 7 James F. W. Jonnston, A, M. Ix is a thing worthy of remark, that the older the human race becomes, and the farther it shoots forward from its origin, the more knowledge do we derive concerning the earth’s “ olden time.” Providence has preserved the records of the earth often in the most singular manner, so that when man has believed every source of information to be exhausted, new light has suddenly burst in upon him from an unexpected quarter to show, him periods formerly, unknown. I For a whole thousand years we have been accuibcdapedl to believe that no important knowledge concerning the doctrines of former times was to be obtained except from the writings of the Hebrews, Greeks, and Romans. . Their literature has occupied the learned not only for its classical beauty, but as the store-house of all that. we know of the older history of man, Many still live. in the opinion that the few ages em- braced. by the history ofthese nations are the only ones, the transactions of which it is necessary to know. Yet they are but as fixed stars of the first magnitude in the infinity of. space, beyond which the telescope shows us thousands as woe? to be known as they. When civilization carried Europeans to fatth: they found there an unknown literature and unknown histories,—histories relating to mysterious and’ strange’ times, and a high though Prof. Agardh on Inscriptions in living Trees. 99 ancient learning. Long was the key to this learning. sought for in vain, till when it was almost despaired of, and when the excitation of curiosity was the only result of research into the historical monuments of India: the unriddling of the Egypt- ian hieroglyphics was at length effected, and singularly enough whole libraries were found at the same time written in the sacred character. This circumstance the more awakens our surprise that we do not possess a single Greek or Roman manu- script more ancient than a thousand years, while in the pyra- mids of Egypt are found rolls of papyrus preserved not, for one but for several thousands of years. Thus the papyrus sprung up on the banks of the Nile, that its imperishable leaf might convey a correspondence from the world most ancient to its newest times. But all these documents give us only an individual history. In later times other annals have been discovered, which com- memorate, not heroes, but ages,—-not_wars and exploits, but the revolutions of the earth. They refer to a still older time, and bear us back to the six days before man was created. It is incredible with what care the earth preserves these memori- als in its bosom. . Insects of a day, embalmed in amber, are preserved for thousands of years. Skeletons, which under present circumstances perish ina few decades,—Palms, whose loose stems decay more speedily than other trees,—the very Algee, so easily destroyed by storms and seasons,—nature im- beds carefully in certain deposits, to constitute together so many hieroglyphics in that writing of which, when destroyed, they shall afterwards testify the existence: as a man who, on the eve of shipwreck, seeing death inevitable, draws up an ac- count of his misfortune, and commits it to the same element which destroys himself, yet faithfully bears his message to the land of his home... One would hardly suppose that inscriptions on trees, the result generally of idleness or caprice, could be ranked among historical monuments. We conceive, that, once overgrown with bark, they are for ever obliterated. But it is not so. The bark only seals it up, and hides it from the gaze of unseason- able or impertinent curiosity. While the tree exists, the in- scription remains entire within, and the older it becomes, the deeper is it buried, and the more safely preserved. It is not 100 ~=— Prof. Agardh on Inscriptions in living Trees. improbable that such iscriptions may be employed as histori- cal monuments, and though they are not so at present, they may lead us to the chronology of monuments whose age we have not hitherto attained with certainty. A couple of ex- amples will explam my meaning. Decandolle states, but without naming his sitalidy, that there were found upon trees in India, inscriptions in the Portuguese tongue which had been inscribed several centuries before, when the land was in the possession of the Portuguese.* Adanson, who travelled in Senegal m 1749, met upon the Magdalena Islands, near Cape Verd, with some’ baobab trees, on which were found inscribed letters of a high antiquity. Tevet had seen the same inscriptions in 1555, although they were still so legible that the names of travellers of the 14th and 15th centuries could be made out. Adanson found the trees six feet iv diameter. He concluded from Tevet’s state- ment, that in his time they were three or four feet, and he found that they could not have been under a certain size when the inscriptions were made. He knew, besides, that a baobab stem of a year old has a diameter of one to one-and a-half inches, of ten years old one foot, and of 30 years two feet. These he considered so many terms of a series, which he filled up accord- ing to the same law, and found, that a boabab tree of thirty feet in diameter would have an age of 5150 years, or little less than the age of the world itself, as deduced from the sacred writings. He adds, that he himself saw boabab trees of twenty- seven feet in diameter, which must, therefore, have an age of 4280, and which seemed in their most flourishing state.t This age, however immense it may appear to our imagina- tion, on closer consideration, does not appear extravagant. Animals bear in themselves the germ of their own dissolution, or the cessation of their organic life. One of the conditions of life is, that the molecules in their solid parts continually chatige ; but as this takes place incompletely, so that a portion always remains in the state of inefficient particles, it must hap- * Decand. Organogr. p. 185. This is probably the same inscription mentioned in the sequel of this paper. i + Decandolle says 1759, which is a mistake. =~ Adanson, Familles des Plantes, p. 214. Prof. Agardh on Inscriptions in living Trees. 101 pen, in a shorter or longer period, that these inefficient par- - ticles become so augmented, that the active molecules are no longer sufficient for the discharge of the vital functions,—the membranes stiffen, and circulation at length stops of itself. Animal life is thus a finished cyclus, necessarily returning to that nothing from which it sprung. Among plants, such a change has also place, but the essential difference between plants and animals lies in the production of new organs. In the ani- mal, a new artery or new lungs are not produced in the place of those which approach their period of inefficiency, but in vegetables new vessels and new parts are continually produced instead of those which have become imactive. Between the bark and the wood is deposited every year a new layer of or- gans, while the inner ones gradually die, and every spring a new foliage shoots forth instead of that which fell the preced- ing harvest. Hence the trunks of trees are often seen en- tirely hollow, and yet bearing a fresh. and flourishing crown, and with such decayed stems they may live for ages. The well known chestnut tree on Mount Etna called Castagno di cento cavalli, because a hundred horses could stand under its shade, has had from time immemorial so wide a perforation in its trunk that two carriages can be driven through it abreast, and a hut is built in the centre. It continues, however, still to be an object of admiration to the traveller.* The hollow * This is different from the account given of it by Brydone, in whose time it was divided into four large arms, the junction of which was beneath the surface—and the priest said that by actual digging he had found they still formed one immense trunk underneath. See Brydone’s Tour—also Library of Entertaining Knowledge on Forest Trees. Damory’s oak in Dorsetshire is one of the most remarkable hollow trees: as it was also the largest oak of which mention is made. Its circumference was sixty-eight feet, and the cavity of it, which was sixteen feet long and twenty feet high, was about the time of the commonwealth used by an old man for the entertainment of travellers as an ale-house. The dreadful storm in the third year of the last century shattered this majestic tree, and in 1755 the last vestiges of it were sold for fire-wood. Thus in this hollow condi- tion it must have continued to live for at least upwards of a century. The Boddington oak also, in the vale of Gloucester, was remarkable for the large cavity it contained. It was fifty-five feet in circumference at the base. The larger arms and branches were gone in 1783, and the hollow cavity was sixteen feet in its longest diameter, with the top formed intoa regular dome; while the young twigs on the decayed top had small leaves about the size of those of the hawthorn, and an abundant crop of acorns.’ The > 102 Prof. Agardh on Inscriptions in living T'rees. stem of the same baobab tree above-mentioned serves often as a lodging to several negroe families, or as a burial place few their dead, which are there changed into mummies. | ial Vegetable life, therefore, is not like that of animals, limited by itself, but, on the contrary, it has in itself the germ of an unceasing duration, since its essence undergoes an unceasing renovation. The causes of vegetable death are to be found in external agents,—in the power of light to accelerate vegetation) and to change leaves into flowers,—in the opposition of gravity to the ascent of the sap, which may finally overcome its organie force,—in the predominance of the vegetable mass over the producing leaves,—and lastly, in external violence, which their fixed growth prevents vegetables from escaping as animals may, Thus it is not impossible that there may be plants in which all the parts are so adapted, that the external can predominate over the internal parts as little in old age as in youth; though in reality, a tree is nearly at all times alike young, since it lives only in its young parts. * Nor are examples of old trees rare. The oak and linden tree may attain to an age of 600 or 900 years. + The seven large cedar trees which still remained on Lebanon in 1787, when Labillardiere observed them, and which had been previously observed and measured by Rauwolf in 1574, Thevenot 1658, Larque 1688, and Maundrell 1696, calculated from the rate of growth of such trees in Europe, must have an age between 1000 and 2000 years; and in the county of Surrey, in England, a Taxus is known so uncommonly thick, that it is supposed to have stood from the time of Cesar. } : . hollow hada door and one window, and a little labour might have yoni ed the tree into a commodious and rather a spacious room.— TRANSLATOR. * For more on this subject see Agardh’s Essai de reduire la Physiologie vegetale a des principes fondamentauz, Lund. 1828. + When old, the.oak increases in size very slowly. In Holt forest Hampshire, there was an oak which, at seven feet from the ground, was thirty-four feet in circumference in 1759 ; and twenty years after, the ete ‘ip cumference had not increased half an inch.—TRANSLATOR. , on } A single individual of the Ficus Indica growing on: the sea coast of Nerbudda occupies a space of 2000 feet in circumference, and can give shel- ter to 7000 men under its shadow. It is supposed to be the same tree de~ scribed by Nearchus, in which case it cannot be less than 2500 years old, Dr Plott mentions an oak at Keicot, under the shade of which 4374 men. had sufficient room to stand.—TRansLaTor. tas Two of the most remarkable trees in Europe for beauty and age, are Prof. Agardh on Inscriptions in living Trees. 408 If, therefore, it be not improbable, that the baobab tree, the stem of which attains to a diameter of thirty feet, or perhaps more, may reach an age of upwards of 5000 years, then this giant of vegetation,—this child of the young earth,—may give us no inconsiderable aid in determining the true age of oe earth’s present surface. The baobab grows only in Adeica: the land of iad and of fables, comprehending vast districts, into which neither the iron nor the civilization of Europe has ever penetrated, and bearing woods still respected by the hand of man,—still inha- bited in peaceful fellowship by the elephant: and the giraffe, which, following the instincts ofself- preservation, have long with- drawn from the presence of their superior enemy. It is pos- sible that baobab trees may have grown up in masses to us -hitherto unknown—living monuments—older than the ruined pyramids, and the abandoned ‘sculptures of India. - Such a land also is New Holland,—a part of. the world: of which we yet hardly know the sea coast. If so enormousia -tree as the Eucalyptus globulus, or the Hutassa heterophylla can grow on places which Europeans possess, it is probable that still greater trees, and still older ones may be found in the wood, to which neither they, nor perhaps the aight have: ever forced their way. But if such data may be of real use to science, and certain enough for. building upon them conclusions regarding »the minimum age of the present vegetation of the earth, the me- thods we possess of reckoning the age of trees ought to be placed beyond all feral and to receive the ernabges paittible precision. ‘These remarks serve fally to show, that it is of high inte- | rest to science to be able to calculate the age of trees, and that every aid which makes that calculation more certain is ‘not -only a gain to natural science, but may become, a gain also, to ‘natural history. If we examine ‘a method by which Adanson leith bis ‘result regarding the age of the baobab, we shall find, that i it the palin trees of Cordova, concerning which, my friend Dr Bowring it in- “forms me that there = exists a moorish ballad with a Spanish yersion.— TRANSLATOR. 2 a > 104 ~— Prof. Agardh on. Inscriptions. in living. Trees. cannot be sufficiently ‘precise, partly because there are only few known terms in the series he adopts.as a formula for his calculations, and partly because even these ave not determined with sufficient accuracy. | Another method, leading more surely to the same end, must thus be sought after as an im- portant pre-requisite to a scientific investigation. Such a method has been long known in the counting of the ; yearly rings in dicotyledonous trees. lo It. has been found that in these trees a layer of wood:ia de- posited every year between the bark and the wood, and that all these layers are distinctly separated by a deeper coloured ring. A tree’s age should in this way be determinable from the number of its coloured rings. | Every one knows that | when a tree is sawn crosswise, such circles are observed, one beyond the other, with a margin between them. ‘These are:con- sidered as the yearly rings, one of which is formed every year the tree lives. This opivion is old, and was adopted ere ngeus. If we suppose a ssutchale tall tree to be increased every year by one shoot in height, then for every new shoot there will arise a yearly ring, and the higher the tree, the less will become the yearly ring which accompanies its annual shoot. Only in the root, then, should there be as many rings as the tree has years. These rings, therefore, have been represented as hol- low cones, placed one over the other, all having their base on the earth’s surface, and varnee? at the extremity of each 4 Fem ly shoot. This opinion involves many suppositions. The most ‘ame portant is, that every year one, and only one, ring is.deposited upon the mass of wood already formed. If this be mot the case, the whole theory is groundless. . This opinion, Professor Link of Berlin, one of thd Gerst phy. siologists of our time, has decidedly opposed in a prize essay, delivered to the Royal Society of Gottingen, and honoured by that body with their prize. He maintains that the wood of the ‘stem increases not only by an external layer, but by an increase in the whole bedy of the wood.* This opinion, which he expressed in his prize essay, has been much criticized, es- * Link, Anat. Gott. pp. 152, 163. | Prof. Agardh on Inscriptions in living T'rees. 105 pecially by Treviranus, and he has therefore sought.to explain it in two later supplements,* in such a way as to bring it near- er to the received opinion. But even in his latest explanation, he denies that the yearly rings mark the yearly increase of the wood. And though Sprengel has also declared himself against the opinion of Link, still in his last reply he continues to per- sist in it.t Duhamel also, thie father of cali phyaehonet decd not consider the yearly rings to be formed at once, but to consist of several smaller layers deposited during the whole year, though varying with the seasons. Even Mirbel does not con~ sider as certain the opinion that the number of rings is equal with that of the years of the tree’s age. § Should we attempt to decide this controversy on physiolo- gical grounds, that decision must depend on the theory of the growth of trees, concerning which authors are still less agreed. It is better to attempt by direct experiments, which cannot be difficult to make, to come to a sure and decisive result. These observations may be made in two ways. The one is by reckon- ing the number of rings in trees whose age is known,—a me-. thod which has been tried, and often cited by Linneus and’ Decandolle. This method is liable to objection from the uncertainty whiitdp will generally exist whether the tree whose age we investi- gate is really the one planted at a given time, or another plant- ed in its stead at a later period. So soon as that time goes beyond one life, some uncertainty must always attend our ob- servations, and thus the conclusion be liable to dispute. The other method is to make an inscription in the wood of the tree, and to reckon the age of the layers that grow over it.. If on examination the rings of wood deposited above an in- scription should prove equal in number with the years that * Link, Nachtrige, &c. Erstes heft. Gétting, 1809, p. 44 folj. Zweytes heft. Gétt. 1812. p. 38 folj. + Aber bezeichnen die Jahrringe die jéhrlich anwachsende Schichten . — bezweifle ich gar schr. Zweytes heft, p. 4. + Link, Kritische bemerkung zu Sprengels Werk iiher den Baw und die Natur des Gewiichse. Halle, 1812. § Elem. de Physiologie, p. 108. 106 = Prof. Agardh on Inscriptions in living T'rees: have elapsed since it was made, we should have eRe a fact the most conclusive of all. we Hei It is of importance, therefore, in this respect, to procure as many and as certain data as possible regarding such inscrip= tions. This physiologists have long ago acknowledged, and we find in consequence a great number of such observations. Fougeroux de Bondaroy, in the T'ransactions of the French Academy for 1777, (which I have not had the fortune to see, since they are not to be found in our library,).has inserted two. memoirs, in which is a collection of such inscriptions found, deep in the wood of trees. In the Catalogue of the Library of Sir Joseph Banks, vol. ii. p. 879, 380, and. in Rausch’s dte- pertorium, are found a list of writings on this subject, which also are not in the library of this university. In the Z'ransac- tions of the Swedish Academy for 1771, Professor E. G. Lid- beck has inserted an account of some observations made by Professor Laurel]. In the Philosophical Transactions for 1739, we remember having read some observations on this subject, by Secretary Klein in.Dantzig, and Sir John Clerk, in Scotland, but which we cannot at present consult, since they are not in the library, and in Decandolle’s Organography, are found still more observations of this kind. A revision and comparison of all these observations would undoubtedly wes cause for many interesting remarks. These inscriptions ina scientific view may be divided into two classes. The one includes those which by their growing into the tree prove the single position, that new layers of wood are deposited on the surface of the old. This fact now, hardly admits of dispute, and new examples can be required only in consequence of Link’s opposition. One of the observa- tions to be found in the Philosophical Transactions. is, thatia deer’s horn bound with iron cramps was found in the centre of anoak. In the same way, in the sawing of a tree in the neigh- bourhood of I.und, of about two feet in diameter, there was found a crooked spike sunk eight inches into the wood, with- out there being any external mark to show its presence. About thirty-five yearly rings lay over the spike, so. that, according to thereceived theory, it should have begunto be covered overabout. thirty-five years before. This specimen is still in my possession. 4 Prof. Agardh on Inscriptions in living.Trecs. 107 ' Both of these observations are more difficult to explain than the in-growing of an inscription; for the inscription is co- vered over by the layer of wood which is deposited every year between the bark and the wood, but the deer’s horn and the head of the nail have naturally stood without the bark. They are explained only by the circumstances that the horn was fastened with iron cramps, and the nail was crooked. These substances, therefore, were firmly fastened to a certain point or a certain place in the interior of the tree. Whilst the tree widened, therefore, and the layers were deposited gradually farther and farther out, it must have happened that these bo- dies at last found themselves within the layers of wood, instead of beyond the bark. Around the nail there remains still a mass of bark, which it carried along with it into the interior of the tree. Tn this respect inscriptions also are not unworthy of remark, as a new proof that the new layers are deposited between the bark and the wood. But this proof is altogether superfluous. Among the inscriptions of this kind which have come to my knowledge there are one or two, concerning which, for another reason, I shall make an observation. Decandolle mentions; that Albrechti, in the year 1697, found in a tree the letter H with a cross over it; and that Adami, under nineteen yearly rings, found the letters J. C. H. M. which was naturally inter- preted Jesus Christus Hominum Mediator. ‘This observation in itself is worthy of little remark ; but the singularity is, that nearly the same figures and characters are found engraved and grown into two pieces of wood preserved in the Museum of Lund. | - In two of these, which evidently go together, and represent both sides of the inscription found at Asum near Ofveds-klos- ter, is seen the following : +“ = And in a third, J H ~ NY A notice in the catalogue of the museum in- Z : forms us that these inscriptions belong to the time of the monks, from which we obtain some idea of their meaning, and why they should be found near a ruined cloister. Unimport- ant.as all this may be, it has nevertheless a remarkable simi- . ; ” 108 Prof. Agardh on Inscriptions in living Trees. larity to observations I have known made in Germany, and therefore I have not thought i it proper to pass them by. I will only add to this, that, in the Philosophical Transactions, is.an observation, that in Hans Sloane’s collection was a piece of wood from the East India islands, with the following Portuguese inscription: DA BOA ORA—*“ (God) grant a good hour.”* It is evident that it is only by rare accident that such inserip- tions can be discovered after all external traces have vanished, Since, nevertheless, we have found so many similar religious inseriptions, more of which are coming to the knowledge of scientific met: every day, they must be more common in the interior of trees than is generally supposed, The other respect in which these observations are important to science is, in case they can show that. a separate layer. is really deposited every year round the older wood, or that the yearly rings mark the tree’s age. This they will prove so soon as we have certain and unobjectionable observations, that a writing was engraved on a certain year, and that, when after a certain number of years it was again brought to light, the number of outer rings was the same with that of the years which had elapsed. But on this point few direct observations have been made, and of those upon record only two have been made in Sweden. Professor Laurell, who is still in lively seibéabbitnnaalt in the University of Lund for his peculiar and often singular opi- nions, made an incomplete experiment of this kind, Hemade two inscriptions in 1748, in the wood of two separate beech trees. One of these was opened in 1764... In 1748 it was six feet six inches, and in 1764 it was found to be six feet eleven inches in circumference. The other was opened in 1756. Both contained the inscriptions within their wood. The pieces of wood on which they had been inscribed were exhibited in the Academy of Sciences in Stockholm by Professor E. G. Lidbeck, and described in their T'’ransactions for 1771. The one ‘piece which had continued to grow eight years had eight “ < In the Philosophical Transactions this is rendered Det ( Deus ) bo- nam horam.” Jam informed by Dr Bowring, that the three words may’ be either an idiomatical expression having this meaning, or that it may sig- nify simply in bona hora, in a lucky hour. It probably implies nearly as much as the Latin, Quod felix faustumque sit. % Prof. Agardh on Inscriptions in living Trees. 109 yearly rings round the inscription, and that which remained sixteen years had sixteen rings. | / This experiment should have been very decisive ; but Pro- fessor Laurel], instead of cutting the inscription through the bark, first took off the bark and then made the inscription. One of these inscriptions was long Vivat Gustaf skrifvit Sr 1748 da jag var 3 alnar och 1 quarter tjakk Os Fig and made a large wound, which was difficult to heal, and caused several rings to be either wanting, or to be very incon- siderable. Thus the true place of the inscription among the . rings was rendered less certain. It became, therefore, a mat- ter of considerable interest to meet with an inscription, the place of which among the rings was sufficiently manifest. Bishop Faxe has lately sent to the Museum of Lund two pieces of wood from a tree which grew near Helsingborg, and, which during the sawing and cleaving separated in such a way, that the inscription stands right on the one piece but re- versed on the other, like a plate and its impression. _ It 1s as foliows :-— d. 21 J 1817 The mscription itself therefore informs us of the time when it was made. ‘The tree was felled in 1828. ‘There ought, therefore, to be ten complete rings, if the common opinion on this subject be correct. On examining the outer piece with a little attention, we see that the innermust ring must answer to the year 1817. Beyond this there are only nine rings ; but that which is nearest to the inscription is broad and brown coloured, and must therefore denote two years, which is also manifested by the fact, that, beyond the inscription either to the right or left, it divides into two distinct layers. It is curious « __? * Written in the year 1748, when I was three ells and ore quarter thick. _ 110 ~—- Prof. Agardh on Inscriptions in living ‘Trees: to see the unequal breadth of the rings.. The outermost, or that which lies nearest the bark, being the formation for 1827, is = 1.2 lines. The second for Ma 1826, is = 0.9 third ¥ a 1825, 16; Bhd Bier fourth == - é A824, 18, =. LaF wees fifth . . 1823, is = 2.0 eee sixth « pt 1822, is — 2.0 —— seventh - te Bk, .18 2.0, nse eighth _ - 1820, is = 2.0 —— ninth 1819 oe 1818, is = 2.0 —— Entire thickness — 15.5, or 13 inches: When we know the place where such a tree has been felled, we can compare the breadth of these yearly rings with the na- ture of the seasons in which they have been deposited. If we are not mistaken in the years, 1824 and 1826 should have been least favourable to vegetation. This in 1826 ean be as- cribed to the great drought which during that year had = an influence on the growth of plants, Another circumstance worthy of remark is, that the tree cleft in such a way, that one-half of the inscription was found on the outer, and the other half on the inner piece of wood. This seems at first sight to confirm the opinion maintained by many celebrated physiologists,—Malpighi, Mirbel, Treviranus, —that the inner layer of the bark is changed into wood, since we might suppose that the portion of the inscription in the outer piece is that which passed through this layer. But we soon find that the mark in the outer piece is not derived merely from the inner layer, but from a portion of the whole bark, which, in consequence of the cutting, became a dead substance, and therefore did not partake in the changes of the rest of the bark, but adhered to the wood like a foreign body. ‘The in- ner inscription is also of an entirely different nature from the outer one. ‘The scar itself appears there more distinctly, and the wood around it has only become brown. But in the outer ' Jayer with the rest of the inscription the letters are indistinct, black, as if burnt, or consisting of a coal-like substance. We Prof. Agardh on Inscriptions in living Trees. 111 can, therefore, draw no other conclusion than that the new layers of wood not only overgrow the inscription in the wood, but that the bark also remaining attached as a dead mass was in like manner overgrown by the wood. If the outer piece be sawn across the inscription, we find traces of the writing for a considerable distance towards the bark. Near the letters it is still black and hollow; but at last there appears only a dark line, which is prolonged to the very bark, on which are some slight protuberances opposite to the inscription, as if it had still a kind of connection with the letters so far within. It may also be remarked, that in this, as in the other similar spe- cimen§ I have seen, the two surfaces do not seem to have grown together. They have separated, as if of their own ac- cord,—the reason probably of their being so often discovered. But the two surfaces are smooth and perfectly fitted to each other, so that every little prominence in the inner has a corre- sponding depression in the outer, as is the case with the exter- nal layer of wood and the bark. The conclusions to be drawn from these remarks are the following . 1°. That a ring of fresh wood is deposited every year around the Re ik of wood which are already formed. ; . Inscriptions may remain unchanged for ages after they are once grown over, and perish only with the substance of the tree. 3°. They do not become indistinct by length of time, but remain as distinct after many hundred years as at the end of the second. ‘ The practical results are not less interesting. 1°. Yearly rings, if it be once established that they mark the age of the tree, may lead us to important data respecting the age of vegetation upon’our earth, since there are trees which have been supposed, with: probability, to have the same age as is commonly assigned to our earth. By counting the yearly rings in such trees, we shall be able, with some degree of certainty, to determine their age, and thus also the mini- mum age of the present surface of ‘the earth. 2°. It is possible that by inscriptions on trees information > 112 = Prof. Agardh on Inscriptions in living: T'rees. may be handed down to posterity in a more imperishable way, than by stone or brass. An oak can preserve an inscription for 500, a baobab for 4000 years or upwards. ref it ¢3 _ Note.—The oak is generally supposed to live 1000 years. (Evelyn, Silva.) In apoem by the Emperor of China, of which a translation was published at. Paris in 1770, under the title of Eloge de Moukden, a treeis spoken of which in that country lives more than a hundred ages, and another, which at the _ end of eighty ages is only in its prime. . The commentators on this passage quote authority to prove that the last men- tioned, “‘ the immortal tree,” is only in its prime at the age of 10,000 years. (Chou King, preface by M. de Guignes.) These fabulous accounts are worthy of credit, in so far as they show the existence of trees probably unknown to us, which grow to an age beyond the date of all other records. Exclusive of physiological considerations, the only practi- cal benefit to be derived from investigations into the age of such ancient trees would be to geology. The value of the in- formation to this science would depend upon the nature of the formation on which they grew. Growing on_ primitive mountains they would be less valuable, but a tree of one, two, or three thousand years old, growing upon a newer sandstone rock, or above a coal formation, or in any similar position in regard to the later strata, would give us a minimum of age for these formations which could not fail to be highly valuable as a datum for calculating the absolute age, not merely of the local deposits but of similar deposits in the other parts of the globe. In New Holland, where such trees are found, and where strata of all relative ages have already been met with, . very interesting observations of this nature may hereafter be made—and travelling geologists may, in other countries, obtain from trees much less ancient, information of no little import- ance regarding the date of volcanic eruptions nih of the ae recent alluvial deposits. —TRransLaTOR. i In connection with this subject, I add the following exintel, which is both interesting in itself and as occurring in an Edin- burgh weekly magazine, dated 4th July 1771. : “ It is obvious, that at every place where a branch grows _ Dr Marianini on a physiological phenomenon, §c. 113 from the trunk of a tree, there must be a knot in the wood which will extend the whole way from the centre to the circum- ference, however great the diameter of the tree may be, if the branch was on it when the tree was felled. But if a branch be cut from a tree while it is growing, the stump from that time ceases to advance in size, and as the diameter of the tree continues to increase, the cortical fibres gradually cover the wood—it is soon healed up—the bark of that place becomes smooth, and the rings of wood are formed with as great regu- larity above the old stump as in any other part of the tree ; so that when this is afterwards sawn into planks, there will be found at every such place a knot in the heart of the wood, which will extend to the same distance from the centre of the tree as was its semidiameter when the branch was cut: but beyond that to the circumference, will be uniform and free from knot or blemish of any kind whatever.” The fact here explained, is precisely similar to the ingrow- ing of insertions, and might be turned to the same account.— TRANSLATOR. Arr. XII.—Note on a Physiological phenomenon produced by Electricity. By Dr Er. Martanin1, Professor of Natural Philosophy at Venice. * Ix my memoir on the shock experienced by frogs at the in- stant when they cease to form the arc of communication be- tween the poles of an electrometer, (see this Journal, No. ii. New Series, p. 286,) I pointed out the difference which exists between the contractions produced by the immediate action of electricity upon the muscles, and which I called tdiopathic ac- tions, and those which proceeded from the.action which elec- tricity itself exercises on the nerves, which preside over the motions of the muscles, and which I have named sympathetic contractions. This difference consists in this, that the zdiopa- thic contractions take place whatever be the direction in which the electric current traverses the muscles, whilst the sympa- ‘ * Translated from the Bibl. Universelle, December 1829, p. 287. NEW SERIES, VOL. III. NO. 1. JULY 1830. H.- 7 114 Dr Marianim’s Note on a Physiological phenomenon thetic contractions take place only when the current which tra- verses the nerves is in the direction of their ramification. According to this distinction we may immediately deduce the principle, that when an electric current traverses any mem- ber of an animal, the two shocks will take place instantaneously if the electricity follows the direction of the nerves; and the idiopathic contraction will alone take place if the electricity travels in an opposite direction. The contractions ought con- sequently to be stronger in the first case than the web result which is confirmed by experiment. | If we put the right hand in communication with the positive pole of a galvanic battery, and the left hand with the negative pole, and if the two communications are established so that the current, passes with the same facility on both sides, we shall — feel every time that the circuit is closed a contraction in the two arms, but it is stronger in the left arm than in the right. > If we make the current pass in the opposite direction, the right arm will, on the contrary, experience a more powerful contrac- tion than the left. If we make one hand communicate with the positive pole, and if the negative pole is in contact with one of the feet, the electricity passes through the nerves in the direction of their ramification in the leg, and not in the arm. Consequently, the contraction is much stronger in the leg, where it is both idio- pathic and sympathetic, than it is in the arm where it is only idiopathic. ‘The same thing takes place when the electricity passes from the shoulder to the hand, from one foot to another, and from the thigh to the foot, &e. yy nee This difference in the strength of the shock, according as.the current goes in one direction or in the other; is greater m somé individuals (particularly in paralytic persons) than in others. I have observed, in electrifying a man struck with hemiplegia, that, in making the current of a battery of eighty pairs ‘pass from the hand to the shoulder, the muscles of the arm scarcely experienced a perceptible contraction, at the same place where they experienced a very powerful one if sae current passed from the shoulder to the hand. : ds In some individuals affected with Lat lena, I ee ob- served that this difference of contraction did not take place in 1 \produced.by Electricity.) do. 115 a limb. ».A woman who had, lost. the use-of her. lower. extre- mities, and of the power of extending them, in consequence of an inflammation in the spinal marrow, felt her left foot contract with more force when it communicated with the negative pole of a battery; but the right foot always.contracted with the same force with whatever pole it, was put in communication, This phenomenon appeared to arise from the right member hav- ing lost the power of experiencing the sympathetic, shock, a loss which might be owing to a diminution. of susceptibility in the nerves, to feel the effect of an electric current which. tra- verses them in the direction of their ramification. If we immerse a finger up to the second phalanx in a cup of water in which is plunged the positive pole of a battery, of from twenty-five to thirty pairs, and if we complete the circuit by touching the negative pole with a cylinder held in the other hand and equally wetted, we shall experience in the finger a shock which extends only to the second phalanx. If we re- verse the direction of the current, we shall feel the shock up to the third phalanx. What appears to me the more remark- able in this experiment, is, that by paying attention to the na- tute of these shocks, we shall feel that the first is more external, and accompanied with a certain sensation which is even a little painful, while the second is more deep, and is followed with no sensation at the place where the finger touches the water. I experienced we distinctly the effects of the two currents with the ring finger of the left hand, that I am confident it cannot be the effect of an illusion produced by the anticipation of it. T am of opinion then, that when the finger touches the negative pole the contraction is stronger, because the édiopathic and the sympathetic shock take place at the same time; and that when the finger is at the positive pole, the shock is weaker and ac- eginpanied with a sensation, because the portion’ of electricity which follows the direction of the nerves, goes in a direction opposite to their ramification. Hence, in placé of producing a shock, it gives rise to a sensation,—an explanation which is conformable to what has been demonstrated i im the memoir 4l- - ready referred’ to. In seizing two metallic cylinders covered with lint, ay and communicating with the poles of a battery of thirty or 116 Prof. Schubler on the influence of Winds forty pairs, moderately active, we experience, beside shocks every time that the circuit is closed, a particular sensation in the palm, which communicates with the positive pole. I have observed this sensation in a distinct manner in some individuals very sensible to the effect of electricity. They felt it to be the same with that trembling which is often felt in the hands or feet when the nerves have been for some time compressed. | It seems to me that it may be of some use to study these facts more profoundly, by submitting to the action of a voltaic current persons in a state of disease. Art. XITI.—On the Influence of the direction of Winds on the Electricity which accompanies the condensation of aqueous vapours in the atmosphere. By Professor ScuusBiEK, Tubingen. * bien Tue inquiries which I have made respecting the periodical changes of the direction of winds, and their relations to the, other phenomena of our atmosphere, led me to examine, with more attention, and under this particular point of view, my. former observations on the electricity of atmospheric precipi- tations.» My principal object was to determine the electricity of the rain or snow which had fallen. during thirty months. The first set of observations was made during sixteen months (from January 1805 to April 1806) at Elvanguen, and the second at Stuttgard during fourteen months, (from. June 1810 to August 1811.) Ellvanguen is situated 1331 feet a the level of the sea, in 48° 57’ 25” of north lat..and 27° 48/ east long. Stuttgard is situated 847 feet above the level of the sea, in 48°.46’ 32” north lat. and 26° 50’ 38” of east. long. During this space of thirty months. I kept account of 412 at- mospheric precipitations. . The examination of the first series of these observations led me to notice a certain order.in the phenomena, the regularity of which became still more sensible by taking into account all the observations. As the appreciation of the electricity of atmospheric preci. * Jahrbuch der Chemie und Physik, 1829. Heft. 8, and Bibi. a. Noy. 1829, p.'203. - om the electricity of aqueous Vapours.— 117 pitations presents several difficulties which are not met with in observations which may be made without meteorological in- struments with scales more simple and more fixed, I ought to say a few words on the manner in which I obtained my re- sults. It often happens, particularly when the rain is tempo- rary, or proceeds from a storm, or when a very minute snow falls, that the nature of the electricity varies several times ; whilst, in other circumstances, it does not vary in its intensity, its nature remaining the same during entiredays. We should, therefore, obtain a very inaccurate result respecting the inten- sity of atmospheric electricity, if we subtracted the observed degrees of positive electricity from those of negative electri- city, as is done in determining the mean temperature from the degrees of heat and cold. I therefore kept a separate account of the degrees of positive and those of negative electricity. When the opposite electricities alternated, I added separately the degrees observed and corresponding to the precipitations, whether positive or negative, and if there was a preponderance of one of the two electrical principles, I kept a proportion- al account. When an atmospherical precipitation gave signs only of one electricity, but without a variable intensity, I took only into account the greatest intensity which I had observed. During most rains the electrometer is indeed in a constant state of vacillation, which depends on the density, the unifor- mity, and the greater or less continuity with which the rains fall on the surface of the ground. Whena storm approaches, the electricity sometimes becomes too intense to be measured, so that I have never pushed the observations beyond the 600dth degree of the electrometer of Volta. It is by means of this electrometer, with straws and a simple condenser, that I made all my observations, employing the same scale which I had formerly used to obtain the numerous results which I have already published. , The following table contains the results of my observa- tions : . 118 _- Prof. Schubler on the influence of Winds Ratio of posi- No. of precipi- tive to negative Mean inten- Mean 4 in 7 tations. _ precipitations. sity. tensity. Winds. Pos. elec. Neg. Posi- Nega- |! j elec, tive. tive. . N. 12+), kL, 100: 91 131 . 99 116 N. E. . 11 12 100:109 105 192 120 E. 3.. 5 100:166 15. 13 18 S, E. 4° %, 1002175) 19:10 | ap S. 5 13. 100: 260 26 23 24 S. W. 28 65 100 : 232 66. 33,» 44, — W. 73 106 . 100:145 75 89. 438 N. W. 25 32 100: 128 31. 46 40 3. North Winds, 48 37 100:114 4 TB Te 3 South Winds, 37 85 100: 230 57 26 39 3. West Winds, 126 203 100:161 57. 38 48. 3. East Winds 18 24 100:133 A aics: dt ae All the Winds, 161 251 100:155 69 43. 53 From this table we may draw the following conclusions : _1. The ratio of the positive to the negative precipitations follows a regular variation, setting out from the north or south wind, and proceeding either by the east or by the west winds. 2. By the north wind the positive precipitations are a lit- tle more frequent than the negative ones. By the south wind, on the contrary, the negative ones are more than double of the positive ones. ; 3. The number of negative precipitations is by the three south winds double of what it is by three north winds. The ratio is 114: 230. 4. The east and west winds give a mean result in this re- spect. .The former, however, approach more to those of the north, and the latter to those of the south. The electricity, indeed, is more frequently negative by the three west winds than by the three east winds in the ratio of 161 to 133. 5. The total electricity of the precipitations is more fre- quently negative than positive in the ratio of 155:100. 6. The mean intensity, on the contrary, of the positive electricity, is more considerable than that of the negative in the ratio of 69 : 43. on the electricity of agweous Vapours. 119 7. The mean intensity of the electricity, abstraction being made of its nature, is strongest by the three north weal and particularly by north east and the north. 8. The electricity is at an average more weak by the clive south winds. Its intensity by these three winds is greater than by the three north winds in the ratio of 39: 75. 9. By the three east winds is stronger than by the three west winds in the ratio of 72 . 48. 10. The mean intensity of the electricity of all the precipi- tations, whether positive or negative, observed. in all the direc- tions of the wind, is almost the same as that of the electricity of the precipitations observed during the west winds alone. 11. It is during the north and the east winds that the op- posite electricities are shown in the most distinct manner, and with an intensity almost equal. ‘The west, and particularly the south, present, on the contrary, a weaker negative electri- city, but a greater number of negative precipitations. 12. The greatest number of electric precipitations takes” place in north winds, and the smallest number in east winds. We obtain from the mean direction of the wind during the whole of the observed precipitations 86°.9 by making use of the formula of Lambert, in which the south is marked by 0°, the west by 90°, the north by 180°, and the east by 270°. The number 86° 9’ corresponds in direction to the wesé with four degrees of declination towards the south west. | I shall now add a few words on the cause of the differences in the electricity of atmospherical precipitations according to the directions of the winds. | At the instant of the precipitation of the vapours contained in the atmosphere, positive electricity seems to be first 'deve- loped, and the negative appears to proceed often from the in- fluence of the first. The precipitations which first take place, whether storm or temporary rain and snows, ‘are commonly positive, and are soon followed by negative electricity of near- ly equal intensity. ‘This alternation often takes place several times, while, on the other hand, we see the drops of rai, hail, hoar-frost, or flakes of snow vary every instant in their size, their density, and their continuity. At the termination, the density becomes weaker and weaker, and finally remains nega- 120 Prof. Schubler on the influence of Winds, &c. tive ; sometimes after the storm a shower falls. which pase hegative electricity. It is not common, however, to see rains which fall regubdil and continuously, show, from their commencement and during several days, only negative electricity. This fact, joined to the weak intensity which this species of electricity generally possesses, seems favourable to the opinion that it is most fre- ~ quently owing to the partial. evaporation which drops of ‘rain experience during their fall. These drops form a species of evaporable base, which becomes negative by the very cireum- stance of the evaporation. This explanation seems to be,con- firmed by the observation of a fact which is owing probably to, the same cause, viz. the strong electricity of the fine. aqueous spray which occurs at the foot of cascades, and which is sometimes so strong near great cascades that the electrometer diverges more than 100°, as I have had occasion frequently to observe in the cataracts of Switzerland. This explanation agrees also with the greater frequency of negative showers by south winds, and of positive ones by north winds. A current of warmer air, and one consequently more light and more elevated, in the first case ought to facilitate. the evaporation of drops of rain during their fall; while, by the colder north wind, which is heavier and nearer the surface of the earth, the clouds have in general a lower position, and the evaporation of the drops of rain is less easy and almost: no- thing. : It follows, also, from the preceding observations, that; we should be often wrong in inferring from the negative electricity of rain the negative electric state of the cloud from which the rain proceeds; for it may happen, that, coming from clouds slightly positive, it becomes negative during its fall by the partial evaporation of its drops. This I have been able to verify by direct observation in a journey which I made in the Alps. Being upon the Righi on the 10th and 11th July at a height of 5140 feet above the sea, I found, by sixteen obser- vations made at different times of the day, that the rain which fell during two days was constantly negative; but as soon as the rain ceased a little, the clouds themselves, with which I was surrounded, were charged with positive electricity. The M. de Serres on Human Bones discovered in France. 121 great intensity of the electricity, the distinct manner in which the two electric principles alternately predominate during north and east winds, seems to arise principally from the dryness which existsin the strata of air, while the whole of these winds reign in the atmosphere ; to which we must add the situation of the clouds, brought by the force of these winds near the surface of the earth, and the electricity of which may. then naturally exert on our instruments a perceptible influence. Li Art. X1V.— Abstracts, with occasional remarks, froma Memoir regarding the Human Bones and objects of Human Fabrica- tion discovered in solid beds, or in alluvium, and upon the epoch of their deposition. By M. Marce. DE SERREs, Professor of Mineralogy and of Geology to the Faculty of Sciences of Montpellier.* Ly this article we propose to make some abstracts, of the first importance to geologisis, from a very interesting memoir of M. de Serres, published in his Geognosy of the Tertiary de- posits of the South of Francé, on the human bones recently discovered in the caves of France. But before giving them, it will be necessary to state certain of the writer’s views on questions which have of late years distracted the minds and embarrassed the views of almOst every geologist. M. de Serres is inclined, more perhaps than any of the other of the continental geologists, to adopt the views of Dr Buck- land, as explained by him in his Reliquie Diluviane. But he proposes such qualifications to the doctrine, as we think can scarcely be acceptable to those who wish to. see in. the phenomena pointed out by our English geologist, traces, not of a partial, but of an universal deluge. After speaking of two great causes which have modified the surface of the globe, viz. the diminution or change of its tem- perature, and the retreat of the seas, in the last of which he leans to the well known opinion of Deluc, the writer proceeds to mention a third modifying cause, which is that of the irrup- * From the “ Geognosie des Terraines Tertiaires, Sc. &c. du Midi de la France,” recently published by M. de Serres. . 122 M. de Serres on the human Bones tions and inundations of the sea. These he supposes to have operated in general in very restrained limits, with the excep= tion, however, of the great inundation, the remembrance of which is preserved’ among all people, to which he attributes the dispersion ‘of the boulders, often considerable, of primitive rocks, very far from’ their origin, and the transport of the di- hiviwm upon a considerable part of the surface of the earth. But it is added by the French geologist, “ this dispersion, although taking place in a manner sufficiently general, has operated, however, with the greatest irregularity, if we may judge from the unequal distribution of the mud, of the gravel, and of the boulders of rocks which are the result of it.” Nor - as far as we can yet learn, from ‘perusing his views, which are exceedingly complicated, is he disposed to think that this ca- tastrophe was in a general manner destructive to the vegetables and terrestrial animals of Europe. But we shall reserve a consideration of his views on this subject for another occasion, reserving this article of our Journal for the more useful pur- pose of giving a detail of facts, rather than solving theories. At the same time, we cannot omit this opportunity of mention- ing our regret that the theoretical word Dilwvium has been introduced in geological language, to which every geologist who has employed the term has given his own peculiar defini- tion. M. de Serres uses it often in his memoir, but evidently ; ) sian sock with embarrassment. “ The word diluvium,” he observes, — “‘ which Dr Buckland was the first to propose, indicates the displaced and transported materials, or the effects of the great inundation which has submerged a portion of our continents : while by alluvium we have been desirous to indicate land, gained by the materials transported by rivers (terrains d’atté rissemens), ‘or land removed since historic times. But all the difficulty consists in knowing where the one‘stops or the other begins.” These introductory observations we have conceived it proper to make, in order that our readers may correctly appreciate the weight which the author attaches to the word Diluvium, whenever he thinks proper to make use of the term. The caverns in which human bones have been discovered in 3 aoa eo discovered in the Caves of France. 123 France, are in number three; namely, of Bize, of Pondres, and of Souvignargues. These will be described in order. 1. Caverns of Bize, in the Department of Aude. [It may be proper to premise, that of the human bones found in the cavern of Bize, M. de Serres gave an account to the Society of Natural History of Paris, of which a notice was published ; but baving changed his views, in consequence of a subsequent revisit to the site, the following may be consi- dered as his corrected narrative. | - Upon visiting for the first time, the caverns containing bones at Bize, human remains were discovered fixed to the rock, and to the roof of the caverns, with other bones and land-shells ; the whole cohering by means of a stalagmitic calcareous ce- ment more or less indurated. Although these bones were in the same calcareous and stony concretions, as those of the different mammalia with which they were associated, I considered; by reason of the small number which I discovered of them, and of their state of preservation, (these bones having lost only in part their animal substance,) that they might have been entang- led there in an accidental manner, and that they were not of the same date as the other remains of the animals with which they were mixed. Since this time, M. Tournal of Narbonne, who is as zealous as heis enlightened, has discovered in the same caverns of Bize, other human bones, not only in the calcareous concretions, or the osseous breccia fixed to the roof or to the walls of these cavities, but also in the midst of the black mud, which is found the most frequently above the red mud in which bones equally exist. Along with these bones he has observed human teeth, marine and land shells of our own epoch, as well»as fragments of earthen ware: The ‘teeth which we have com- pared, resemble the first molar, and; like those of ‘the other animals which are mixed with them, we perceive that they pre- serve their enamel.» But what they have peculiar to them is, —the roots are so much changed as to adhere firmly to the tongue. The fragments of pottery jumbled together in the same mud in which human bones, as well as the debris of terrestrial mam- > 124 M. de Serres on the Human Bones -malia of extinct species exist, do not announce a very perfect state of the arts; for certain of them had not been baked in any furnaces constructed for this purpose. Some had been fabricated from clays, which had not previously been washed, whilst others, in short, indicated potteries still: more coarse. Among the nuinber of fragments collected by M. Tournal, some were covered over upon one of their sides with a very fine blackish dust, as if the earth of which they are wrought had been exposed to the action of fire and smoke. These earthen-vessels, totally bruised and fractured, were no less shivered than the bind with which they were mingled... The distinctness of their forms is tou great to lead us to suppose, that the fragments of them had been dragged along, or con~ veyed from a distance by waters, which had for a long time exercised an action upon the substance which composed them.’ This action has been sufficiently violent to shiver these earthy vessels, but not enough to blunt their forms, or to round their angles. The ‘land and sea shells, which we find mixed with bones and fragments of pottery, may be all referred to species like those which we have at present. Among the former, the Cy- clostoma elegans, the Bulimus decollatus, and the Helix ne- moralis and nitida are the most common; as in the instance of the caverns containing bones at Lunel-Viel. These land shells still preserve, in part, their colours, as well as the marine species which are associated with them, and among which: we may dis-» tinguish the Pecten Jacobeus, the Mytilus edulis, and: ane Natica millepunctata. * The mud and the osseous breccia in’ which these shells, these earthen fragments, and these human bones are discovered,’ enclose also terrestrial mammalia, which appear to be extinct races, and others which do not at present exist in our country. Among theextinctraces may beremarked a species of Cervus, of, the subgenus Anoglochis, which, like the Chevreuil, has. the: first. antler remote from the crown. | And as the individuals re- * Although Lamarck cites this Natica as particular to the Indian ocean and to the coasts of Madagascar, it is, however, very common upon all the shores of the Mediterranean. discovered in the Caves of France. 125 ferable to the Anoglochis, which exist in the caverns of Bize, are of a size which surpass that of the common stag, the ex- tended wood of which have a distinct flattening, it is impossible not to regard the race as extinct, since the chevreuil is, in the present creation, the only Cervus the first antler of which is apart from the crown, or the only living Anoglochis.* This chevreuil, remarkable for the form of his wood, his size, and the differences which he exhibits when compared with all the species of known stags, whether living or fossil, has been named Capreolus Tournalit by M. de Christol, i honour of the geo- logist to whom the discovery of the caverns of Bize is due. With this great Capreolus, or Anoglochis, another description of them has been discovered, as well as one of the true cervus; neither of them, however, appearing to have any representative among our actual races. M. de Christol has given them the name of Capreolus Lufroyi, and Cervus Reboulii,—species which we shall describe in the work which we are preparing in concert with M. Tournal upon these caverns. | And again, along with these chevreuils and: cervi of lost species, have been discovered the bones of bears which belong to races considered up to the present day as antediluvian, since they resemble the Ursus (128 M. de Serres on the Human Bones ler race than the large horses of the caverns of Lunel-Viel ; 4th, of two species of Bos, one of which was the Aurochs; 5th, of a description of sheep ; 6th, of a single species of Cervus, probably of a cataglochis of the size of the stag; 7th, of a species of bear; 8th, of a badger; 9th, of the Hyena spelea, a fossil kind which approaches the most to the spotted hyena, or the hyena of the Cape; 10th, of Rodentia, the size of the hare and the rabbit-—These remains of mammalia were ac- companied with the same land-shells that we found associated in the caverns of Lunel-Viel ; that is to say, with the Cyelo- stoma elegans, Bulimus decollatus, and the Helix rhodostoma and variabilis. 3. Cavern of Souvignargues. The second cavern of the environs of Sommieres (Gard), that of Souvignargues, has had formerly many openings. At the present day there only exists one of these, the others hav- ing been obstructed by parts of the cave giving way. The opening by which we penetrate it is a very irregular hole, the large diameter of which is little more than fifty centimetres. It is necessary, in this case, to craw] with some inconvenience upon the belly for a distance of about six metres, after which we are enabled to get upon our knees. This corridor, bound-— ed on each side by cavities more or less spacious and very deep, terminates by enlarging itself. In fact, at the end of about sixty paces, it is abruptly expanded,’ and several very large chambers, covered over with fine stalactites, unexpectedly in- vite the attention of the curious. A thick, glacis-formed, sta- lagmitic bed covers there the diluvium ; and, as it is very hard, we do not know if there exist in it bones or not. Our operations were thus limited to the exploring of the mud which is found at the extremity of the corridor, in the place where the cavern begins to be enlarged ; the mud being there completely exposed. The diluvium, the thickness of which in this part is about two metres, is red, tenacious, and apparently argillaceous. It encloses a great quantity of land- shells, like those which exist in the caverns of Pondres and Lunel-Viel ; and likewise some of the Helix nemoralis and algira. Under this horizontal bed of mud containing land- “discovered in the Caves of France. 129 shells, we observe at first, a layer of gravel about seventy cen- timetres thick ; this bed being mixed with red clay. The gravel gradually thins off, and, in proportion to its disappear- ance, the bones begin to be exposed. It is in this bed that M.-de Christol has detected several molar teeth of the Bos and of the cervus, an ungual phalanx of an individual of the solipeda, a molar tooth of the bear, and several human bones, as of the scapula, humerus, radius, perineum, sacrum, and two vertebre. It is to be remarked, that under these bones there only exists a depth of twenty centimetres of dilu- vium, so that they were very close to the rock upon which this mud had been deposited. This position was one which was too important to leave undetermined, with the view of esta- blishing, if by any circumstance the different beds of gravel had undergone any derangement; but, as we were well con- vinced that there was not any interruption between them, which is even the case with the superior bed, containing shells, nor any sort of dislocation, it is difficult to resist the conclusion, that whether it be the bones, or the different sorts of gravel or mud, they are found in the position, and in the situation in which they had been originally placed. Such are the interesting circumstances under which human remains have been discovered in the south of France. M. de Serres adds in a note, that another discovery, though of frag- ments of pottery only, was made by M. Delanoue, in the caverns of Miremont, which contained numerous remains of the Ursus speleus. - These are the chief extracts which we shall give from this important memoir. Much of the remaining part of it is de- dicated to a recital of the chemical means employed to deter- mine the relative antiquity of the bones, on the assumption, that it would bear a proportion to the carbonizable animal matter contained in them. ‘The human bones of these caves were again compared with the oldest ones which could be col- lected from Gaulish sarcophagi, some of these having been interred for so long a period as fourteen or fifteen centuries. The result of these experiments was to justify the reference of the human bones found in these caves to an epoch far remoter than what could be assigned to those which were deposited not NEW SERIES. VOL. III. NO. I. JULY 1830. I 130 M. de Serres on Human Bones, &c. long after the Christian era. It was not, however, so easy to determine from this test the comparative age of the ossiferous deposits themselves, when considered exclusively ; ; the greater or less abundance of the animal matter appearing to vary with the circumstances under which they were found imbedded, as for instance with their greater or less protection from the ac- tion of external agents.. However, as far as could be ferred, the presumption was, that the ossiferous deposits of the caverns of Lunel-Viel and of the Hermite, in which no human remains had been detected, were the most ancient. The fragments of pottery which were submitted to the in- ‘ani tios of the antiquaries of Montpellier, appeared to them to indicate the first infancy of human arts, being pronoun- ced to belong to times anterior to the introduction of Roman ins ventions into Gaul. For instance, the earth of which they had been composed did not seem to have been washed before being used. Earthen vessels had been dried or hardened by the sun, or by a fire kindled on the occasion, but had not owed their baking to furnaces constructed for the purpose, which was shown by their external surfaces only having undergone the ac- tion of heat. But to conclude.—F rom the circumstances under which these bones are discovered, M. de Serres has very readily arrived at two natural conclusions: 1st, That, since the appearance of mam upon the earth, certain species of terrestrial. mammalia have been completely destroyed, or at least have ceased to exist in the different parts of the globe which have beem explored up to the present time; 2d, That the remains of our species are incontestibly mixed, and are found in the same zeological cir- cumstances as certain species of terrestrial mammalia, consi- dered up to the present time as antediluvian, such as the bear of the caverns of Miremont and of Bize, together with the rhinoceros and. the hyena of the caverns of Pondres and Sou~ vignargues, Besides. these conclusions, there is a train of others whiall M. de Serres has hazarded. But, as these involve in them the details of many geological phenomena. peculiar to the South of France, into which we have not space to enter, we shall postpone to another occasion our observations upon thera, on account of thegreatlength of discussion whichthey are calculated toinvolve.. Mr Johnston on the double chlorides of Gold. 13} We shall merely hint, that the following is the state of the diluvian question :-— In the first place, many.a are e inclined to think, and we believe with reason, that, in the present geological epoch, proofs ate afforded of Europe having been visited by one, or even more deluges, and that, at the least, one of these was overwhelming in its effects. . But it does not appear evident, that this deluge was an universal one, since no traces of it can be detected in many very extensive districts of the Continent. * Secondly, Although it is probable that the deluge, or de- luges with which the Continent of Europe has been. occasion- ally visited, must have been highly destructive to many tribes of animals, yet it follows, as a corollary from the preceding conclusion, that the destruction could not have been univer- sal; and that we must have recourse to. other causes if we would explain the extinction of many ancient races of animals. Into this question we may enter at some future period. is Art. XV.—On the double Chlorides of Gold. By James F. W. Jounston, A.M. Communicated by the Author. Tue double chlorides of: gold with sodium and potassium have been examined, the former by Figuier and Dr Thomson, the latter by Javal. The two analyses of the sodium salt agree very mogely with each other. They are as follows: - Thomson. —_ Figuier. Chloride of sodium - i ow 14.85 14.1 yf Chlorine 17.82 : nn Chloride of gold G'0"P? foes \ 67.38 693 Water - - - 17.82 16.6 © 100 100 And Dr Thomson deduces the composition to be 1 atom bi-chloride of gold 34 1 atom chloride of sodium 7a} 50.5 8° water - - 9 But this analysis bears in itself a strong argument against its * Dr Hibbert, we understand, made many observations on + oe pot 19 the nein during his late visit to the Continent. 182 Mr Johnston un the double chlorides of Gold. correctness. The oxide of gold is as ter-oxide, and the chlo- rides by solution in water are supposed to become muriates, in consequence of the chlorine uniting with the hydrogen, and the metallic base with the oxygen of the water. When the sodium chloride of gold, therefore, is dissolved in water, three atoms of oxygen will unite with the gold to form ter-oxide ; two of the hydrogen which is liberated will combine with the two of ‘chlorine, forming muriatic acid; and the third ‘will escape. Or vice versa, on evaporating the solution to obtain the salt in the crystalline form, there will be a redundancy of oxygen, which must in its turn fly off. But no such pheno- mena take place on dissolving or crystallizing the salt ; it can- not, therefore, contain gold in the state of a i-chloride. This difficulty was seen by Dr Thomson, and alluded to in his “* Attempt” (vol. 1. p. 447,) but, trusting to the accuracy of his analysis, he left the matter undetermined. In the eleventh volume of the Edinburgh Transactions (p. 23) he has returned to the subject, and endeavoured to confirm his analysis of the sodium salt by a similar analysis of the simple muriate of gold. When the solution of gold in aqua regia is evaporated by a gentle heat, a salt is obtained in long pale yellow four-sided prisms, and in truncated octohaedrons. . This isan acid salt, -acompound of muriatic acid, and oxide of gold ; or, as many chemists consider it, a compound of muriatic acid and chlo- ride of gold. When these crystals are fused and further heat: ed, they give off water, muriatic acid, and chlorine; forminga ter-chloride of gold which, if not sufficiently heated, may con- tain a portion of the acid salt,—or if heated too much, may be partly changed into proto-chloride, or it may be a mixture of all three. | . This ¢er-chloride, according to Berzelius, consists of Theory. f£xperiment. 1 atom gold =25 64.935 65.09 © 3 atoms chlorine = 13.5 35.065 34.91 38.5 100 100 If this ter-chloride be farther heated very gently till it ceases to give off chlorine, it is changed into a yellow proto-chloride, consisting, according to Berzelius, of “Mr Johnston on the double chlorides of Gold. 183 ) . > Theory. Experiment. Latom gold - 25 84.745 85 } atom chlorine 45 15.255 15 29.5 100 100 Water decomposes this chloride into a solution of the com- -mon muriate and metallic gold. Such are the relations between gold and chlorine according ‘to Berzelius. Dr Thomson, on the contrary, states, that ‘* the -muriate of gold cannot be converted into a chloride by heat); -at least all my attempts to obtain a chloride by that fivogee -have ended in disappointment.”* | Dr Thomson dissolved a known weight of gold in nitro-mu- riatic acid, evaporated to the state of a brownish-red solution ; and weighed the solid mass it formed on cooling. ‘The gold in this salt was thrown down from its solution by a plate of copper, and the copper by caustic potash. The liquid neutra- lized: by nitric acid was thrown down with nitrate of silver. The sum of the gold in the state of peroxide, and the muriatic acid equivalent to the chlorine obtained, deducted from the weight of the saline mass, was considered as water, and the following composition made out : 9.25 28 [sare 5.625 There are two objections to this analysis: Firsé, it will ap- pear from a consideration of what has been stated above, that the saline mass might be a mixture, and that no characters are given by vhich, we could determine it to be a single defi- nite compound ; and, secondly, the analysis itself was too com- plicated. It is necessary to take these objections into conside- ration, as the result obtained by Dr Thomson in his two ana- lyses, if correct, would form a very remarkable anomaly among chemical combinations. Since caustic potash throws down a ter-oxide of gold from the muriatic solution, we should infer that salt to. be a ¢er-muriate also. It is not easy to conceive, indeed, how it can be anything else. . 2 atoms muriatic acid 1 atom peroxide of gold 5 atoms water ‘ *\ Edinburgh Transactions, xi. ps» 29. 134 Mr Johnston on the double chlorides of Gold. During a residence in Stockholm towards the end of last ’ year, I was invited by Berzelius to assist him in analyzing the chloride of gold, with the view of clearing up’ the anomaly which Dr Thomson’s paper presented. ‘The common muriate or chloride is not easily weighed owing to its deliquescence, nor is it easily obtained unmixed ; the double salts have neither of these disadvantages ; they were therefore selected for examina- ‘tion. I. Chloride of gold and sodiwm.—Dr Tkbmeon bearne this salt by heating it alone in a green glass retort, and caus- ing the chlorine disengaged to pass through ‘a solution of ni- trate of silver. The loss, after adding the chlorine and gold, was considered to be water. The salts analyzed in Berzelius’ laboratory were introduced into a glass tube drawn to a fine point at the one end, and having a bulb blown in the middle to contain the salt. A spirit lamp was applied to the bulb, and dry hydrogen gas passed through as long as any muriatic ‘acid was given off. ‘The loss of weight indicated the chlorine combined with the gold,—and. the water ; the weight washed out by water was the alkaline salt, and the remainder was pure gold. ie 1°. 2.06 grammes of the: salt in small yellow prisms and needles, and dried in the open air, being decomposed by hydro- gen gas, and the common salt washed out, evaporated and heat- ed to dull redness, gave loss— | being, Chlorine and water, 0.742 = 36.024 per. cent. ~ Gold, — 1.02 = 49.51 © Chloride of sodium, 0.298 = 14.466 2.06 100. ‘ _ 2°. 3.026 grammes of the same salt’ were mixed with six grammes anhydrous carbonate of soda, and heated to inci- pient redness for half an hour over a spirit lamp. The salt dissolved out by water left of gold 1.4978 grammes = 49. 497 per cent. The solution saturated with nitric acid, and preci- pitated by nitrate of silver, gave 4.3347 grammes, | fused chlo- ride answering to 35.34 per cent. of chlorine in the salt. The chloride of sodium obtained in the former experiment = 14.466, contains 8.835 chlorine, consequently 35.34—8.835 ‘Mr Johnston on the double chlorides of Gold. 135 = 26.505 is the chlorine in combination with the gold, And 36.024 — 26.505 — 9.519 =the water... 8) Therefore the composition of the’salt per cent: is Chloride of sodiuit, > et 14.466 Chloride of gold, Ghats oot 76.006 Water, 9. 519 . Now 8.835 x 3= 26. 505, the chlorine combined with the gold, therefore the gold is combined with three, times as much chlorine as the sodium, and is a ¢er-chloride The atomic constitution of the salt is as follows: 1 atom chloride of sodium, = 7.5 = 14.85 per cent 1 atom ter chloride of gold, © = 88.5 = 76.23 4 atoms water, = 45 = 8.92 51.5 100 , 3°, From these experiments it appears that Dr ‘Thomson has erred in both of his analyses as much. as 8.835 per cent. or } of the ‘whole’ chlorine combined with the gold. » This wide difference between the results made me_ desirous of, re- peating these experiments on my return home before publish- ing those of Berzelius, more especially as the results of Dr Thomson were so nearly corroborated by the previous analy- sis of Figuier. I formed, therefore, a quantity of the salt, and crystallized it from a solution containing excess of common salt. Prepared in this way, it gave me in two different analysis 16.2 per cent. of common salt, being nearly two per cent too much. I puri- fied the salt, therefore, by the addition of more gold, and three successive crystallizations, when by spontaneous evaporation, which in this salt proceeds more slowly than in either of those hereafter described, L obtained it in large reddish. yellow prisms and four-sided tables, an inch in length, and some of them near half an-inch in breadth, emitting a metallic sound when thrown upon glass. 33.038 grains of these large crystals, after drying at a heat of 150° were exposed to a current of dry hydrogen gas, and * These calculations are according to Berzelius’s numbers. ~ 186 ‘Mr Johnston on the.double chlorides.of Gold. lost 11.994 grs, = 36.303 per cent. = the water. and chlorine in combination with the gold. The chloride of sodium washed out, again pveporaielie! to dryness and heated, was perfectly white, and weighed 4. 852 = 14.687 per cent. The residual gold heated to redness weighed 16.192 = 49.01 per cent. Again—25. 781 grs. in large plates heated with carbonate of soda in the manner above described, the salt dissolved, the excess of carbonate decomposed by nitric acid, and the chlo- rine thrown down by nitrate of silver, gave 36.532, fused chlo- ride of silver = 9.0299, chlorine* = 35.0255 per cent., er the whole chlorine contained by the salt. Now the chlorine in 14.687 grs. common salt obtained in the former experiment = 8.8122 grs. Therefore 35:0255—8.8122 = 26.2133 the chlorine in com- bination with the gold. ane 36.303—26.2133 = 10.0897 = water Cae in the Sait The whole analysis consequently is as follows : Chlorine, 8.8122 } 14.687 Chloride of sodium, Sodium, 5.8748 Chloride of gold, arinte il 75.2233: ; | Water, 10.0897 _ 100 The result of these experiments shows, that the large cry- stals made use of contained upwards of one per cent. of water lodged mechanically among the plate s. The ratio of the chlorine in combination with the gold, to that united with the * This is calculated from Dr Turner’s results, as detailed in his paper in the Philosophical Transactions. He found 100 metallic silver to be equivalent to 132.83 of fused chloride. + This salt may be fused without undergoing any appreciable loss of chlorine, and, probably, when in large crystals this is the only way of free~ ing it from mechanical water. I heated 25.781 grains of large plates to the melting point, and kept it in occasional fusion for two hours, when the en- tire loss was only 0.29, a large portion of which was probably uncombined water. | Mr Johnston on the double chlorides of Gold. 137 sodium, is the same as in the analysis of Berzelius, though not so rigidly exact as in his probably more accurate experiment. The following table gives a view of all the weg ye of’ this salt hitherto published. Theory. Figuier. Thomson. Berzelius. Johnston. Chloride of Sodium 7.5 14.85 14.1 1485 14.466 14.687 : Chlorine 13.5 26.73 17.82 26.505 26.2133 Chloride of gold } Gold 25. 49.5 3° 49.51 49.501 49.01 Water 4.5 8.92 16.6 17.82 9.519 10.0897 — —_— ’ —_——-- 50.5 100° 100 100 ~=100 100 II. Chloride of gold and potassium.—Of this salt only one analysis, I. believe, has yet been published, that of Javal. * He found it composed of. Chloride of potassium 24.26 Chloride of gold... - 68.64. Water -— - - 7.10 100 “This salt parts with its water much more easily than that of sodium,—it effloresces even when exposed to the air, and loses its whole water at the temperature of 212°. It crystal- lizes in four-sided prisms and needles, and in large brilliant thin plates, resting on their edges, and increasing upwards in the liquid, while those of the sodium salt are formed always along the bottom of the vessel. In an acid concentrated solu- tion it forms. hard prisms,—in a more neutral, fine needles. The large plates are obtained only from a solution with excess of potash, and by spontaneous evaporation. The crystals do not long retain their water. Some fine prisms picked out and “preserved 1 in a corked tube were covered with a yellow eet in a few weeks. . 1°. 3.141 grammes of the salt in minute yellow needles, and previously dried by pressure upon bibulous paper, were heated on the water bath. It lost 0.255 — 8.099 per cent. Fused afterwards in a tube, it gave only a trace of aqueous vapour, showing that it contained no appreciable quantity of water. * An. de Chim. et de Phys. xvii. 337. 138 Mr Johnston on the double chlorides of Gold. _ 2°, 3.545 grammes ofthe dry salt heated to fusion in a cur- rent of hydrogen gas till all traces of muriatic acid ceased to be evolved, lost 0.798 = 22.51 per cent. = ines in marie tion with the gold. The chloride of potassium being washed out, left 1. 8485 of metallic gold = 52.143 per cent. a The salt therefore was composed of Anhydrous. Chloride of potassium, 25.347 23.294 Chlorine, 22.510 20.687 Gold, 52.148 . 47.919 - Water, : 8.100 100 100 This analysis agrees very nearly with that of Javal, who cal- culated his salt to consist of 3 Chloride of potassium + 2 ter-chloride of gold. This composition, calculated according to the atomic num- bers of Thomson and Berzelius, gives the following propor- tions per cent. Berzelius’s Thomson’s numbers. numbers. Chloride of potassium, 27.074 27. 014 Chlorine, 25.430 Q5. 592 Gold, ~ 47.493 47. 393 These proportions differ from the experimental results by quantities far too. great to be accounted errors in the analysis, as I can bear ample testimony. tothe care with which the aboye analysis was performed. by Berzelius while Ishad the honour of assisting him. In consequence of an error:in the calculation, however, by which this theoretical composition was made to differ only one per cent. from his. experimental result,* Berzelius adopted Javal’s view of els constitution a - *® This calculation was as follows: Chloridé of potassium, =| S77 Chlorine, 23.42 Gold, -V&8 tive 51.81 This, it will be seen, differs from the experimental results only by one per Mr Johnston oi the double chlorides of Gold. 139 the salt, and:concluded that the sodium and_ potassium. chlo- rides of gold are unlike in composition, as he had formerly found to be the case with the similar salts of rhodium.*,.’ On my return home I was anxious to verify this analysis also, and formed therefore a portion of the salt by mixing the solutions of the simple chlorides. | I obtained large, well-de- fined, brilliant, four-sided oblique prisms, speedily, becoming opaque. ; 1°. Of these large prisms 50.154 grams were heated in a current of hydrogen gas, when the loss in weight was 17.4 grains = 34.693 per cent = water and chlorine, g The gold left after washing the residuum, weighed 23.5 = 46.861 percent, And consequently the composition of the salt was Chloride of potassium, = 18.446 Gold, ; = 46.861 Chlorine and water, = 34.693 100 2°. This salt, as I have already stated, soon parts with its water, and it was by the heat of a water-bath that it was rendered anhydrous by Berzelius’s experiment.) But to take away all chances of error to which this method is liable, from the possible loss of chlorine and from the want of any fixed rule for determining when the water is entirely dissipated, I took 25.893 grains of the same large crystals, being all I had left, and heated them in a porcelain crucible for half-an-hour with 50 grains dry carbonate of soda. The. salt being washed out left of gold 12.15 grs, = 46.92 per cent. The solution seiaiented! with nitric acid and thrown down by cent. ; and, assuming it to be correctly calculated, the composition of Javal ‘was obviously made out. The error must have arisen entirely from the haste with which the note of the experiment given me by Berzelius was drawn up, I never thought of making the calculation myself till the im- possibility of obtaining any thing like the same results in repeated analy- ses of the salt led me at last to examine the numbers. * See page 22 of this pee Number. 140 Mr-Johnston on the double chlorides of Gold. nitrate of silver gave of fused chloride, 35.666 grs. = 8. sia chlorine — 34.0416 per cent. Now the chlorine in 18.446 chloride of atti; nevohilna to ‘Thomson’s numbers, is 8.7375, and 8.7375 x4 = 34.95, which is very near the quantity of chlorine obtained. The gold, therefore, contains three times as much chlorine:as the potassium, and is consequently in this salt: also in the state of a ter-chloride. * Taking three-fourths of 34.0416, we have 25.5312 for the chlorine in combination with the gold, and 34.693 — 25.5312 = 9.1318 for the water contained in the salt. We have there« fore the following constitution. | ; Chlori Fy Chloride of potassium. Potuiaaial foasion 18.446 | , Chlorine, 25.5312 Ter-chloride of gold. Gog" Seaqi” | 72.3922 Water, 9.1318 100 If we calculate this composition we find the chlorides united in the proportion of atom to atom, and that the water comes nearest to four atoms, as follows. Theory. Experiment. Berzelius. 1 atom chloride of potassium, = 9.5 = 18.095 18.446 23.294.) 1 atom gold, 25. 47.619 46.891 47.919 3 atoms chlorine, 13.5 = 25.714 25.5312 20.687 | 4 atoms water, 4.5 = 8.572 9.1318 98.100 52.5 100. - 100 100 — The great difference between my own results and those of Berzelius and Javal I can account for only by supposing that, my own salt being in large well-defined crystals, must’ have been the purer, or that there are two double chlorides of gold and potassium, of which the minute prisms analyzed in Berze- lius’s laboratory was a mixture. At all events, the agreement of my results with atomic numbers shows the salt I ie 0 20 to have been a definite chemical compound. — | III. Chloride of Gold and Ammonium.—Of this salt no analysis I believe has yet been published. When in Copen- ‘Mr Johnston,on the double. chlorides of Gold. 141 hagen. Dr Forchammer informed me that he had made some experiments upon it, and found, that, when decomposed by a red heat, it left 48.1 percent. of gold, and that it contained about 13 per cent. of water. These quantities, deduced from incomplete experiments, differ materially from my results as stated beneath. | This salt is easily formed. If neutral solutions of chloride of gold and sal-ammoniac be mixed and set aside for sponta- neous. evaporation, the salt speedily deposits itself in small golden yellow. prisms and needles, or in large right ‘prisms with rectangular terminations, and often with two of the op- posite solid angles replaced so as to form right six-sided prisms.. If the solution contain excess of sal-ammoniac, it forms large plates of a beautiful golden yellow colour and’ pearly lustre, increasing upwards, and presenting in their outline the shape of a large flat prism with. low pyramidal terminations. When removed from the mother liquor, the prisms are yellow and transparent. Pressed between folds of bibulous: paper, they retain their transparency for a short time—but exposure to the air for a few minutes—a slight warming of the paper— or contact with the fingers, renders them opaque. By expo- ‘sure to the air for a length of time, it is gradually decomposed, and if in thin scales, dissipated, leaving a black stain. When heated in a water bath, it gives off all its water and undergoes a kind of semifusion, which causes the crystals or their powder to cohere. ‘Ihe colour is deepened also, but becomes again pale yellow on cooling. At a higher temperature it melts in- to a reddish liquid, and is decomposed, giving off chlorine and sal-ammoniac, and leaving metallic gold. This decomposition takes place so easily, that by a careful regulation of the heat, both the ammonia and the chlorine may be driven off without fusing the salt, and the metallic gold obtained in the form of the original erystal—showing that during this decomposition no'change takes place in the relative position of the atoms in the interior of the crystal. A similar fact has lately been ob- served in regard to the crystals of nitrate of silver. The water or ammonia or both vary in this salt so much, that though I have made ten or twelve analyses of it, I have never obtained the same per centage of the constituents in any two . 142 Mr Johnston oie the double ohlorides of Gold. experiments. The water varies from 4 to 6 per cent. accord- ing- as the salt has been more or less exposed to the atitio- sphere or other causes, so that the salt in the state of crystals, from the uncertainty of their state of dryness, cannot bé eni- ployed to ascertain the per centage, nor can we depend upon their retaining all the chlorine when dried in a water bath, as the odour of this gas is developed at a very moderate tempe- rature. © The volatile nature of the alkali in this salt is another obstacle in the way of a rigorous analysis, as it is not easy to collect and weigh it. The following experiments, however, are sufficient, I think, to determine its constitiition to be si- milar to that of the two salts above described. 1°. The mean of five experiments gives for the water dtiven off by the heat of a water bath 4.7 per cent. 2°. A portion of the salt decomposed by héating’ with car- bonate of soda; and the solution afterwards satutated with nitric acid, and thrown down by nitrate of silver, gave of gold and chlorine in the following proportions :— Gold, 7.52 = 1 atom. Chlor. 5.477 = 4.04 atoms. The chlorine and the gold have therefore in this salt the same ratio as in the other double salts. 3°. 32.467 grains of large distinct crystals dried in the ont and become opaque, were heated in a stream of hydrogen gas. Water passed over at first, mixed with a minute portion of acid. This ceased before the salt fused ; it was theréfore ale lowed to cool, and weighed. The loss was 1.8 grains = 5.54 per cent. Heated. again till all was driven off there remained 53.22 per cent. of gold, the additional loss being 13.387 = 41.23 per cent. which ought to be something less than the full we of the chlorine and ammonium. Now 3 atoms chlorine = 38/738 per cent. And 41.23 — 28.718 = 12.492, which is less than the thole weight of sal-ammoniac. Therefore we have the composition. Gold = 53.22. per cent. Chlorine. = 28.718 poser i) Sal ammoniac = 12.492 4+) 2+ Water = 654 — —— Mr Johnston on, the double chlorides of Gold. 148 The sal-ammoniac is here too little, and the gold ‘too much. I have tried to collect the sal-ammoniac and weigh it, but the chlorine carries off a portion of it, even when made to pass through water, so that I have contented myself with inferring its amount; in which, after the chlorine is determined, there cannot be any great error. _ 4°. The mean of the last compared with, five other expeti- ments, gives for the gold in the salt 52.66 per cent. These experimental results agree very nearly with the fol lowing constitution :— Theory. haepelinheait: T atom gold = 295 — 52.682 = 52.66 . 4, atoms chlorine = 18 = 37.894 = 38.33 -}-atom ammonium* — 225 = 4737 = 43° 2 atoms water = 225 => 4737 => 4&T 47.5 100 ~~: 100 IV. Red double chlorides of Gold—The salts of sodium and ammonium above described dissolve in nitro-muriati¢ acid with effervescence and evolution of deutoxide of azote and chlorine, and give solutions varying’ in colour from a reddish-yellow to a deep blood-red. On cooling, these so- lutions deposit yellow prisms resembling in appearance the original salt, but having the property of becoming deep red when heated to about 300°. - If the solution be evaporated to dryness, a blood-red mass is obtained, deepening often in the ammonium salt to a dark purple, + which on cooling at- tracts moisture with great avidity, becomes of a dirty brown, and finally of a yellow colour,—and resolves itself at last into a yellow liquid. This liquid, concentrated by heat, becomes again deep red, anid concretes into’a mass of deep red prisms, which change, as before, in a cool and moist atmosphere. In this state the salt is partially decomposed by alcohol into the alkaline chloride which remains undissolved, and a * {atom ammonium = 1 atom-ammonia + L atom hydrogen. The constitution of this salt requires I think, that we should consider sal- ammoniac as a chloride ; otherwise we should have one atom of a chloride united to one atom ofa muriate, a kind of compound not hitherto recognized. + This very deep colour is generally attended by a partial decomposition. > 144 Mr Johnston on the double chlorides of Gold. greenish * yellow sediment, showing to the microscope a mix ture of brilliant particles of gold, and changed instantly by a drop of muriatic acid into pure metallic gold of the common appearance. The alcohol also dissolves a portion becoming deep red, and giving by evaporation deliquescent reddish-yel- low crystals in four-sided prisms, becoming deep red by a heat of 212°. If the heat be raised a little higher, the salt fuses, dries, and .the microscope shows the crystals to have now the form of very minute cubes. Alcohol has on these cubical crystals the same effect as at first, decomposing one portion and dissolving another, which gives again yellow prisms with a shade of red or brown, succeeded on the application of heat by dark red cubes.. Water dissolves the red mass with’ resi- due of a little metallic gold, the result, probably, of previous decomposition. This solution gives a mass of red prisms, more deliquescent in-the ammonium than in the sodium salts, and changed by a continuance.of heat into red cubes. If the salt be previously in solution from the presence of a. small quantity of moisture, alcohol does not decompose it... Like the yellow salts it is decomposed by .caustic ammonia, which throws down a light brown precipitate. By a similar process we should obtain, a red nalaaaiaiel salt also. The potassium salt above analyzed. dissolves like, the others in aqua regia, and gives a red solution ; but evapora- tion to dryness did not give me a red mass, nor did the yellow prisms obtained become red by an elevation of temperature. Its formation in this case may be dependent upon circumstan- ces of which I am not at present aware. _. Berzelius+ has described similar red salts of iridium, osmniam, rhodium, and palladium, formed generally after the same man- ner. Magnus? has also formed a like class of red platinum * Berzelius states, that if the solution of chloride of palladium in caustic ammonia be evaporated to dryness and treated with water, a greenish-yellow powder remains, consisting of one atom of the chloride, and one atom of ammonia. Magnus formed a similar compound of platinum. It is possible that the greenish-yellow powder above-mentioned nay bear some amnlogy to these, though it can hardly be of the same composition, + Kong. Vetensk. Acad Handling. 1828. { Poggen. Annal. xiv. 239. Mr Johnston on the double chlorides of Gold. 145 salts, so that those now indicated were alone wanting to, sia up this entire family of analogous compounds. | In the state in which they are obtained by the process above described, these salts seem imperfect. There must be some yet unknown .process for preparing them in a better defined and more permanent form. The ammonium salt I first. ob- tained accidentally, and in a state in which I have been en- abled to preserve it, with a slight loss of colour, fow several months. 19K I mixed a solution of sal dinintiing with an acid solution of gold in a common wine-glass, and set it before a fire to.evapo- rate. To hasten the evaporation I shook it up occasionally on the sides of the glass, by which they became covered with a thin film of the yellow salt. This film I found was redis- solved by the acid liquid with effervescence. Concentrated in this way the solution deepened in colour to a blood red, and, on removal from the fire, deposited a great number of minute bright red cubes, mixed on cooling with minute crystals of the yellow salt, from which it was difficult by mechanical means en- tirely to separate them. They dissolve in water more easily than the yellow salt. -A portion of these minute cubes in a close tube became yellow in a few weeks, without changing their form. Some larger crystals which I was fortunate enough to obtain on one occasion, were more permanent, insoluble in alcohol, and af- fecting a form derived from the cube. These crystals, as well as others of the yellow salts, Dr Brewster has kindly undertaken to examine and describe. The salt obtained by both processes is probably the same, though, by the method last mentioned, I could not form any red sodium salt. The peculiar relations of ammonia to che- mical bodies, however, are sufficient to account for this dif- ference. I have not analyzed any of these salts; they are obviously anhydrous, as are the red salts of the other metals described ‘by Berzelius and Magnus. In the corresponding salt of. pal- Jadium the metal is n combination with an atom of chlorine more than in the yellow salt. The phenomena attending the solution of the red gold salts, and the interchange of yellow prisms and red cubes, do not seem to argue the presence of NEW SERIES. VOL. III. NO. I. JULY 1830. K 146 = Mr Johnston on the double chlorides of Gold. any higher compound in them than the common ter-chloride of gold. The bichloride in the red salt of palladium is de- composed by warm water with evolution of chlorine; the red salts above described suffer no such decomposition. The pro- bability is, therefore, that they differ from the. ate salts simply in being anhydrous. V. Yellow double chlorides of gold and the other bases.— Except with chloride of barium I have not formed any of the other double chlorides of gold. Want of time has prevented me from introducing into this paper an intended description and analysis of the double salt of gold and lithium. In regard to the other bases I have been in a great measure anticipated by Bonsdorf, in a long and able paper inserted in the T'rans- actions of the Swedish Academy for 1828, and translated in- to Poggendorf’s Annals, vol. ‘xvii. p. 115 and 247. In this paper * Bonsdorf deseribes a great number of double chlérides of mercury, gold, platinum, and palladium, under the appel- lation of chloro-mercuriates, chloro-goldates, &c. in illustration of a view which he entertains, that the chlorides, iodides, &. of any particular metal, act as an acid to the chlorides, iodides, &c. of all the more electro-positive metals.+ ‘To render the present paper more complete, I shall subjoin what he has stated in regard’ to the chloro-awrates or double chlorides of gold. ‘They were all formed by mixing a solution of the crystalline compound of chloride of gold and muriatic acid menitioned in the beginning of this paper, with solutions of the other metallic chlorides, and gently heating the mixtiré’ till the acid was driven off. By re-soluition in water the salts easi- ly crystallize, either by spontaneous evaporation or over sul- phurie aeid.. ST hey are all’ very soluble in water and’ aleo- hol. 1. Chloride of Gold and Barium forms a age salt in low ¢ ‘The slate in this paper have been long kept back. by, va soletane nate fire at Abo in September, 1827, by which, along with. the, university, all Bonsdorf’s preparations and implements were destroyed, and his labours interrupted. . + The same view is entertained by Berzelius in regard to the sulphur salts, or combinations of a sulphuretted electro-negative body with the sul- phuretted electro-positive metals. jar : Mr Johnston om the double chlorides of Gold. 147 rhombic prisms or tables, having an obtuse angle of 105°. It generally deliquesces and can be preserved only in’a dry at- mosphere. 1 have formed this compound, and obtained from it a red salt ‘also by the method above described. 2. Chloride of Gold and Strontium forms a yellow salt, shooting into rhombic. prisms, which are permanent in the air. ‘38. Chloride of Gold and Calcium.—This salt crystallizes in long rhombic prisms, commonly uniting sideways into a straw-like crystallization. | .562 grammes of the salt, heated till the water and chlorine were driven off, left .389; from which water extracted .077 chloride of lime, leaving .262 of metal- lic gold. And as 262 takes 140 of chlorine, the chloride of gold weighs 402, so that, taking the deficiency for water, we have Calculation. Experiment. Chlorine. _ Chloride of gold, 1 atom © 73.54 71.53 24.91 Chloride of Fane! l atom 13.45 13.70 8:68 . Water, 6 atoms 13.01 14.77 . 100 * 100 In this, as well as in the a iising Ro a: it will be seen that Bonsdorf takes it for granted that the gold is. combined with 3 atoms.of chlorine, a point which it has been the object of the former part of this paper to prove. 4. Chloride of Gold and Magnesium.—By evaporation over sulphuric acid this compound is easily obtained in low rhombic prisms of nearly 72° and 108°.. The salt, which is of a beautiful citron yellow, is permanent in winter + but de- liquesces in summer. A slight heat. drives off its water and melts it intoa dark brown liquid, which gives off chlorine and at length dries. This salt was analyzed by exposure to a stream ‘of hydrogen gas, and afterwards treated with dilute muriatic acid, by which the gold was obtained, evaporating the solution, and heating to redness for the magnesia, and calcu- lating the chlorides. The result gave “ These calculations are made from the atomic weights of Berzelius. + The winter of Abo! 148 Mr Whewell’s Observations on Calculation. Experiment. Chlorine. Chloride of gold, latom, = 6610 64.50 15.91 . Chloride of magnesium, 1 atom, = 10.40 11.00 ee Water, 12 atoms, — 23.50 24.50 100 ~—-:100 5. Chloride of Gold and Manganese crystallizes in yellow rhombic prisms, which deliquesce in summer, but are perma- nent in winter. ‘This salt is isomorphous with the preceding. _6.. Chloride of Gold and Zinc forms a salt in colour and general appearance like the magnesium salt, and isomorphous with it. It is permanent even in slightly moist air. Its com- position is undoubtedly analogous to that of the magnesium salt. aod 7. Chloride of Gold and Iron. This salt does not exist. When the two chlorides are mixed, the iron, as is well known, takes up more chlorine, and precipitates the gold in the metallic state. 8. Chloride of Gold and Cadmium forms a darker yellow salt in prismatic needles, which are permanent in the air. 9. Chloride of Gold and Cobalt is obtained by spontaneous evaporation in long exceedingly oblique rhombic prisms. The salt is dark yellow and is unchanged in the air. 10. Chloride of Gold and Nickel crystallizes in low rhom- bic prisms, isomorphous with the zinc and magnesium salts. It deliquesces in summer, but is permanent in winter. By solution in nitro-muriatic acid and evaporation, all these salts will probably give red anhydrous compounds, — / PortosEe to, 7th June 1830. Art., XVI.—Observations on some passages of Dr Lardner’s Treatise on Mechanics. By the Reverend W. WHEWwELL, _M.A.,, F. R.S. Professor of Mineralogy, iyo In a Letter to Dr Brewster. im My prKar Srp, . I wave already had occasion to show, im the pages of your Journal, that I consider as a matter of some importance the Dr Lardner’s Treatise on Mechanics. 149 soundness of the reasoning employed in establishing the fun- damental doctrines of motion. The science of Mechanics, in its true and genuine form, is by far the most perfect specimen which we possess of the inductive philosophy :—of principles collected from extensive experiments and observations, elevat- ed to the highest point of generality, successfully applied to the determination of phenomena most numerous and complicat- ed. But this science will deservediy forfeit the distinction which we thus claim for it, if we become careless about the mode of proving our general principles ; if we try to make them appear to be mere identical propositions ; and if we in- terpret them ina lax and wavering manner, in order to suit the different occasions on which we may wish to apply them with- out the trouble of accurate deduction. With these views I need make no apology, I trust, for offering you a few remarks on some passages in Dr Lardner’s volume on Mechanics, recently published as part of his Cabi- net Cyclopedia. Any one who takes an interest in the puri- ty of our scientific logic, will be particularly solicitous that it should not be corrupted without notice taken, through a work which seems to have so fair a prospect of extensive circulation. And I think, that whether or not such persons may assent to my views as to the true foundations of mechanical reasoning, they will agree with me, that nothing ought to be allowed to pass without animadversion in an exposition of these doctrines, which, coming from a mathematician of acknowledged emi- nence, can reasonably be accused of being erroneous or un- meaning. Dr Lardner has, in page 45, given his readers Newton's three laws of motion in the form in which they were stated by’ their author. He then proceeds to declare his opinion, that they have little or no utility, being either identical or super- fluous propositions. This assertion, I confess, I cannot but contest. Upon the most mature consideration which I have been able to give the subject, in the course of many years, I have always arrived at the conviction that these three laws, when made as distinct as is possible, are the simplest result of the analysis of the 150 Mr Whewell’s Observations on phenomena of motion, and the ultimate and general Pee from which ‘our synthesis must proceed. © If Dr Lardner, instead of taking these sites in their egal form, had introduced other principles equally distinct and clear, which might supersede the use of the laws in explaining the doctrines of motion, (a. proceeding which is very possible) I should not have thought any: criticism necessary ;:"but. as: it appears to me that his slighting notice of Newton’s propositions is combined with some errors as to the nature and evidence of the principles which he has employed, and with a want of strict reasoning in his demonstrations, [shall endeavour to show, that we may yet find our advantage in adhering a ieee longer to this long-received code of ** the three laws.” F Of the “ first law” Dr Lardner says, that “ when inertia and force are defined, it becomes an identical proposition :” on which I have to observe, First, that in defining inertia he as- sumes the first law of motion ; Secondly, that he not only does this, but he assumes this law to be demonstrated ‘by a priori proof, instead of resting on ‘the ea of ope rience. He ‘says “ Inertia, or inactivity, signifies the total alae of power in a body to change its state of rest or motion.” Now motion is here (see art. 41,) used in the sense of velocity, and to say that the body has no power to change its velocity, is to say that the velocity will not be changed except’ some power is exerted to, produce such an effect ; it is'tovassert that the velocity will not undergo ‘any change in consequence’ of any elementary and universal law of nature, independent of any particular circumstances of the case; an assertion spneeseaah Is exactly the first law of motion. This fallacy, which I think can hardly ba denied to incall is, it may be observed, of very frequent occurrence in ‘Treati- ses on Mechanics, and the temptation to commit it seems to re- side in the word velocity, (or motion, used as equivalent to velocity.) This word does, in fact, express a property: or re- lation belonging to the space through which a body. moves, and to the time which it so employs; but this relation being once marked by asingle word, the word is supposed.to desig- nate a property, not of the motion but of the body itself; and Dr Lardner’s Treatise on Mechanics. 151 this property is then conceived to have a permanency, like the form or size of the body, , till it is altered Se external agents. The mistake, considered in this point of view, is a curious and instructive instance of the influence which words exercise “upon our reasonings;, It is no doubt, one of the highest me- rits which a, scientific language can possess, that. it should make as simple and_ brief as possible the expression of true elementary and important propositions. . But it was sufficient- ly proved to the mathematical world, by the long controversy about the two meanings of the word, force, that, the selection of the fundamental propositions, and of the definitions of terms which were most convenient, may sometimes be a matter of doubt and of choice. And it might have been supposed, that the opinions held in that case by eminent mathematicians, would have been a sufficient lesson to warn reasoners on such subjects. against the mistake of supposing that they can, by choosing their, definitions, make the laws of motion become necessary truths. . We may, however, observe, that the gene- ral tendency to, the fallacy under consideration, and the diffi- culty of convincing a,person at first that it has been incurred, show,,in a very striking manner, how completely the appro- priation of a word in such a case as this, of ‘* velocity,” answers the purpose of giving to the complex idea of relation which it marks, unity of form and facility of use, and the delusion fol- lows close on this facility, ,. We imagine that the relation must be permanent, because it has been distinguished from all others, and is found in possession of a ready and familiar name; al- though, in fact, the thing designated by the name might be, so. far as our means of judging are concerned, variable and fluctuating from one moment to another, _ To illustrate. this, point a little farther, let us ‘suppose the case to have been otherwise than it is; and let us see what changes in, our language, as well as in our reasonings, would have been requisite to adapt the pretended proof above-noticed to such.a.case. ,._It will, at least, involve no contradiction if we suppose, that all bodies, by a. universal Jaw, tend to move amore and, more slowly as long as they continue in motion. Let it.be supposed, that, independently of all reference to ex- 152 ‘Mr Whewéll’s Observations ‘on ternal causes, (such being‘ of course excluded ‘in our present speculation) a body would, in«all cases, lose one thousandth’ (or any other given fraction) of its velocity in every second. Such a law of motion is quite consistent and possible, and would, perhaps at first sight, appear to most persons more probable than the law which really obtains. In this case, if we take two equal successive units of time, a body moving freely would describe in those times two spaces bearing a cer- tain ratio; a ratio invariable for all bodies, spaces, and veloci- ties, and depending only on the unit of time. And this ratio, being an element of universal occurrence and use in consider- ing’ the motion of bodies, would naturally have some name fixed upon it for the sake of convenience. It might perhaps be termed “ the progressive rate” of the body. It would, on the suppositions here made, be found that m all motions, ex- cept'so far as they were disturbed by external causes, the pro- gressive rate of bodies was the same ; that whatever motion was given to a body at first, the progressive rate, and the con- sequent dependence of the space upon the time, continued un’ altered. ‘The inertia of a body might then naturally and pro- perly be described as the total absence of power in a body to change its progressive rate; and bodies would be’ said ‘to move according to the “ law of inertia” when they moved with this gradually diminishing velocity. | sede ie It would, therefore, be easy for those who wrote treatises on mechanics in a universe so constituted, to make short work of the proof of this law, by enumerating inertia, sO DEFINED, among the elementary and universal properties of matter; and then by asserting, that, in virtue of this property, a body could no more alter its progressive rate than it could put itself in motion when at rest, or stop itself at once. All this might bé said, and yet it‘is manifest to us, knowing such a ‘state of things to be purely hypothetical, that no proof of such’a law could be obtained but from the observation and mensuration of phenomena. . sg sinis It may, moreover, be observed, that, if such a law had been true, there would have been, corresponding to each initial ve- locity of a body, a certain space which the body would describe before its motion was extinguished ; and this space no circum- Dr Lardner’s Treatise on Mechanics. 153 stances, except an alteration of the imitial velocity, could have increased or diminished. It would have been quite allowable to call this space the motion belonging to the initial velocity ; and, speaking conjecturally, it appears to me probable, (on the hypothesis already made, and considering the mode in which ‘such errors have been applied,) that it would have been so cal- led. On this supposition, mechanical writers would have been able to assert, quite as truly and positively as they can at pre- sent, that no body has any power to increase or diminish any quantity of motion which it might have received.* It seems to me curious that Dr Lardner should have been satisfied with the reasoning which he has employed in the proof of this law, or property as he terms it, of inertia, since he is thus led to use expressions which are at variance with his own observations on the proper phraseology for this subject. In p: 7 he makes an objection (as appears to me not well found- ed,) to the use of the term force for the cause of motion ; and he adds, in the way of reason for his objection, that, * when causes are referred to, it is implied that effects of the same class arise from the agency of the same cause. However pro- bable this assumption may be,” he says, “ it is altogether un- necessary.” But at page 28, when he is proving the property of inertia in his sense of uniform velocity, he says: * the same power which would cause a body moving at ten miles an hour to increase its rate to eleven miles, would also cause the same body at rest to commence moving at the rate of one mile an hour.” Here it isassumed, that the same cause which aug- ments the velocity of a body already in motion, must necessa- rily reside and operate in the same body at rest. Indeed, there is in this case a good. deal more taken for granted. It is implied that this cause would not only operate in the two cases, but, moreover, that it would operate according to certain * It is easy to obtain the formule for the motion of bodies which would be true in the case supposed. If | + 2:1 be the ratio of the velocity in two successive seconds, c the initial velocity, v that after ¢ seconds, » — e(1 + n)—*. Also the whole spacedeseribed with the initial velocity a will 1 : ik . be c = * Ifn= T0090’ the ratio of the velocities in successive seconds will be 1001 : 1000, and the whole space described, 1001.c. 154 _ Mr Whevwell’s Observations, &c. rulés which belong to the second law of motion ; adding exactly as much, velocity to a body already in motion as it would have communicated to the same body at rest., However true this supposition may be, manifestly it ought neither to be asserted wihout, proof when. it is introduced, nor introduced at all in proving a proposition, more elementary than. itself; and one which is necessarily supposed when the rule, concerning. the addition of velocity is established. I am.afraid many of your readers will consider these; cFone sions as trifling,and unprofitable subtleties; and will think that it cannot be a matter of any consequence in, which.way: we ‘prove that which all allow to be true. .In excuse) of my oc- cupying your pages with remarks on, these subjects,|I.might plead, that sound thinking and accurate expression, have ,usu- ally been considered as essential to the respectability of science ; and, that if its more, general diffusion is to be accompanied by a contempt of these qualities, the advantages of the spread’ of knowledge. will be grievously diminished, . But, if sucha doc- trine be thought to be of too severe a cast for modern times, at any rate we may venture to say, that, if.it is not worth while being right in. such points, it cannot, be necessary, to waste words-on them at all; and that those. who deliver a.decided and professional opinion, upon these reasonings, impose upon themselves the obligation of that.,patience.and accuracy, of thought which such investigations require. . Above all it, is, un- reasonable to treat slightingly the abstruser speculations be- - longing to the fundamental points of mechanical philosophy, and at the same time to carry these speculations, so far, and to conduct them so erroneously, as, to lose sight of. the depend- ence of our principles upon experience. It is doing, great. in- justice to this magnificent department of human knowledge, to exhibit. its doctrines as a set of consequences flowing merely from the relations of certain abstract terms and_ arbitrary definitions, instead of making them, as _ they ought to be made, a truly inductive science, concerned with, and collected from the observation of physical facts. The collection, the analysis, and the generalization of these facts, occupied several generations of acute and laborious intellects ; and that the principles now appear almost self-evident, shows how com- Mr Coddington on the improvement of the Microscope. 155 pletely the task was executed, and how well the expressions belonging to the science answer the purposes contemplated in their selection; but we shall make a strangely perverse use of these advantages, if we begin to imagine that the laws of mo- tion are constituted.or upheld by the words’ which are conve- nient for their exposition. 7 .. Iam -persuaded that Dr Lardner will ‘not ‘be disposed to take offence at these observations, which have ‘for their object to place in the true point of view the fundamental principles of a science which he has: successfully cultivated. It :will be clear to all your readers, that what has been said implies no blemish in that part of the treatise which is employed in the application of these principles:—I am, my dear Sir, yours, &c. Trinity CoLLeceE, CamBsrner, W. Waewe tt. May 10, 1830. Ant. XVIL—On the Improvement of the Microscope. By _.H, Coppineron, M. A. F. R.S.: Fellow: of. Trinity Col- lege, and of the Cambridge Philosophical Society. * Amone the numerous excellent stiggestions which Dr Brews- ter has from time to time thrown out to those engaged in the theory or the practice of Optics, there is one which appears - to’have been most unworthily, and most unaccountably, ne- glected. It is that of substituting a sphere for a lens in the construction of a microscope. ‘Thisis the more surprising, as many persons of great eminence have, of late years, turned their attention to the improvement of this instrument, in which pursuit they have spared neither time, labour, nor expence. ‘The only reason which I can give for this is, that as, until the investigations of Professor Airy, which are contained in the present volume of the T'ransactions of this Society, nobody, with the exceptions of Dr Young and Dr Wollaston, ever dared to approach ‘the thorny subject of the oblique refraction of a pencil of rays by a lens; almost all other persons have been satisfied with endeavouring to show, as distinctly as possible, one individual point of.an object; trusting that the rest would * Slightly abridged from the T'ransactions of the Cambridge Philosophi- cal Society. . 156 Mr Coddington on the improvement of the Microscope. follow of itself, or giving up, as hopeless, the idea of produc- ing a good and large field of view. To those who have studied the construction of the com- pound microscope, an analogy presents itself, very naturally, between that instrument and the telescope. In each there is an image formed, which is seen through one or more lenses, constituting what is technically termed in the former case he body, in the latter the eye-piece. The progress of these instruments has been curiously similar in some respects. The first step of any consequence in the case of the telescope, was Huyghens’s eye-piece, which, be- sides the merit supposed by its author, of diminishing the errors arising from aberration, had one, much more important, which he did not contemplate, the correction of the coloured fringes, seen about every part of the image, except that pre- cisely 1 in the centre. Ramsden then succeeded in making an eye-piece, which gives a flat field of view, when that point is particularly important, and finally, the instrument has been made perfect, by substituting for the simple object glass, an achromatic and aplanatic combination of lenses. In the com- pound microscope, the first point, (the correction of the co- loured fringes,) has been completely attained ; on the second, much labour has been bestowed by practical opticians, but with little success ; the third has lately occupied some of the . most distinguished theorists and artisans, who have been emi- nently successful, but the difficulty and expense necessarily attending their processes, are so great, that but few persons can derive any benefit from their exertions.* In making a comparison between the telescope and micros- cope, it must be observed, that some difficulties, and sources of error, which in the former are so small as to have been over- looked, are in the latter of the greatest and most palpable im- portance. The image produced by the object glass of a teles- cope is usually considered as perfectly plane, and equally dite * Mr Tulley has just finished an achromatic microscope ordered for Lord Ashley, about six months ago. This instrument, which I have seen, is a masterpiece of art, but I believe that the above eminent optician has been obliged to make the object-glass with his own hands, and the price is far beyond the reach of most naturalists. 4 Mr Coddington on the improvement of the Microscope. 157 tinct in all its parts, and this supposition is quite. sufficiently accurate, because although the image given by a lens with centrical pencils, is on the whole very much curved and very indistinct, so small a part of it is employed in this case, and that only the most. perfect, that the defects are usually quite insensible in practice. I have shown, (Treatise on the Reflection and Refraction of Light, Art. 145.) after Dr Young and Professor Airy, that if we represent by A, the aperture of the object glass, s, the distance of a point of the image from the axis, J; the focal length of the lens, k, the distance of the image from the lens, the indistinctness is proportional to the diameter of the least space over which a pencil is diffused, the value of. which is Az? hf Now in a telescope, x being nearly equal to the semi-aper- ture of the field-glass, is very much less than f, to which & is equal, and as a high magnifying power is produced by means of a powerful eye-piece, applied to an object glass which is never changed, and as the apertures of the lenses used for eye-pieces, of the same kind, are usually proportional to their focal Sagthen sue higher the magnifying power, the less is the fraction —, f° Ca For instance, in a five foot telescope, it is seldom, if ever, greater than ie and often very much less, so that the value of the quantity 5 a is about am Ina microscope, on the other hand, f is a very small quan- tity, though & is not so, and the magnifying power is raised by applying an object-glass of shorter focus to the same body. The following ue mie I believe, such as might fairly occur : rAz2 Ae ge ex Gs SH k=. These give ae =F which as, with different object-glasses, z and & are. constant, and 2 usually. proportional tof, may be considered as s its gene- ral value. 158 Mr Coddington on the improvement of the Microstope: Again, in a telescope, the portion of the image used is sen/ sibly flat, though the radius of curvattire of every such image, is about ths of the focal length of the object-glass: but in the microscope it is evidently far otherwise, so that were the whole image distinct, it would still-be impossible to have any great extent of it distinctly visible at once; and this objection applies in full force to the most perfect achromatic object-glass. Now with a sphere, properly cut away at the centre so as to reduce the aberration, and dispersion, to insensible quantities, which may be done most completely and most easily, as I have found in practice, the whole image is perfectly distinct, what- ever extent of it be taken, and the radius of curvature of it is no less than the focal length, so that the one difficulty is en- tirely removed, and the other at least diminished to one-half. ' Besides all this, another advantage appears in practice to attend this construction, which I did not anticipate, and for which I cannot now at all account. I have stated that when a pencil of rays is admitted into the eye, which, having passed without deviation through a lens, is bent by the eye, the vision is never free from the coloured fringes produced by excentrical dispersion. Now with the sphere I certainly do not perceive this defect, and I therefore conceive that if it were possible to make the spherical glass on a very minute scale, it would be the most perfect simple microscope, except perhaps Dr Wol- laston’s doublet, than which I can. hardly imagine anything more excellent as far as its use extends, its only defects being the very small field of view, and the impracticability of apply. ing it, except to transparent objects, seen by transmitted light. Now the sphere has this advantage, that whereas it makes a very good simple microscope, it is more peculiarly fitted for the object-glass of a compound instrument, since it gives a perfectly distinct image of any required extent, and that, when combined with a proper eye-piece, it may without diff. culty be employed for opaque objects. I have, therefore en- deavoured so to combine .it, and this has been my principal difficulty ; for the systems of lenses which I have found employ- ed for this purpose, are so improperly constructed, that I se been forced to have one made from original calculations, and get ‘Mr Coddington on the improvement of the Microscope. 159 tools constructed on wisiyiode, which has pases 2 been attend- ed with some delay. The principle which I have adopted, after one or two a vious trials, may be explained as follows.. One great cause of the excellency of Huyghen’s eye-piece, is the condition which he himself designed to fulfil, namely, that the bending of the pencil is equally divided between the two lenses. Now this may be done for a microscope, thus : Let O (Fig. 2, Plate I.) be the centre of the sta OF the place of the field-glass, E - eye-giass. Let OF = = 2 inches, (for exqple} FE = 1 mech. Speen on the focal Kage of the field-glass be 1 inch, ~ eye glass — } inch These values satisfy the conditions of achromatism, and it will easily be seen, that if Y be the place where the pencil tends to éross the axis after refraction at the field glass, and x, that where it actually crosses after emerging from the eye-glass, the angle of flexure, at each lens, is double of the original inclina- tion of the pencil to the axis. ‘This simple system is, however; not applicable, as it.is im- possible-to satisfy the condition necessary for perfect distinct- ness; much less that for destroying, as far as possible, the con- vexity: of the field: These may, however, be very readily satisfied by employing two lenses of equal power, in each places instead of'one. “The most proper forms of the lenses are those shown in Fig. 8, the field-glassés and the: second) eye-glass being of the meniscus form, and. the first eye-glass equi-con- vex. I have found no sensible error arise froni’ the substitu- tion of plano-convex lenses for the meniscus glasses, which are difficult and expensive to form. Theory indicated) a fur- ther flattening of the field, to be made by separating the eye- glasses a little, which requires the distance of the first eye- glass from the field-glasses, to be diminished by about ‘half as intich ; I cannot say, howevér, that I perceive any improve- ment arising from this) alteration in practice, and as the field is quite flat enough with the ¢ye-glasses in contact, and any further diminution of the apparent convexity, can be gained 160 Dr Brewster on the law of only by a sacrifice of distinctness, I cannot on the whole re- commend it. I have not, however, yet had the instrument in. a sufficiently perfect state of adjustment, in other respects, to be able to give a decided opinion on this point. This system, as it will easily be seen, gives a magnifying power of 3 to the eye-piece, soas to multiply, by that number, the power of the object-glass. It would be easy, if necessary, to produce a higher magnifying power, by employing lenses of shorter focal lengths, regard being had, in each case, to the proper condition of achromatism. Thus several different eye-pieces might be in- serted at pleasure into one tube, in the same manner as it is us- ual to vary the magnifying power of a telescope.’ I have not yet tried the effect of this, but I suppose it may be necessary in applying the microscope to opaque objects, as the difficulty of illuminating them almost precludes the use of a powerful ob- ject-glass. I do not pretend to give this as a perfect instrument—much less as one that will answer all purposes; but: having tried it in a very rough state, and with a moderate magnifying power, on various delicate test objects, all of which it shows very satisfactorily, not excepting the striz on the scales of the Podura, which Mr Pritchard, the inventor of the diamond and sapphire lenses, says are only just discernible with the most perfect instruments, I see no reason to doubt that, when care- fully executed, it will be found very effective, and that the naturalist may be furnished, at an expence not exceeding five or six guineas, with a microscope which will perform rests all that can be expected from that instrument. : Fig. 4. represents the sass as I have directed it to be made by Mr Cary. fe - ‘Trinity CoLiEcE, i. CopDINGTON. » April 23, shi ART. XVIII.—On the ae of the partial polarization of Light by reflexion. By Davin Brewster, LL. D, F.R.S. L. & E.* Iw the year 1815 I communicated to the Royal Society a se- ries of experiments on the polarization of ‘light by successive * From the Phil. Trans. 1830. Part I. p. 69—84. ¥ E9trrt! the partial polarization of light by reflexion. 161 reflexions, which contain the germ of the investigations, the results of which I new. propose to explain. hows _ From these experiments it appeared that a given peneil of light could be wholly polarized at any angle of incidence, pro- vided it underwent a sufficient number of reflexions eithér at angles wholly above ot wholly below the maximum polarizing angle, or at angles partly above and partly below that angle; and it. was scarcely possible to resist the conclusion that the light not polarized by the first reflexion had suffered a physi- cal change at each action of the reflecting force which brought it nearer and nearer to the state of complete polarization. This opinion, however, which I have always regarded as demon- strable, appeared in a different light to others. Guided pro- bably by an experimental result, apparently though not really hostile to it, Dr Young and MM. Biot, Arago, and Fresnel have adhered to the original opinion of Malus, that the reflected and refracted pencils consist partly of light wholly polarized, and partly of light in its natural state; and more recently Mr Herschel has given the weight of his opinion to the same view of the subject. Under these circumstances, I have often returned to the in- vestigation with renewed zeal; but though the frequent repe- tition of my experiments has more and more convinced me of the truth of the conclusions which I drew from them, yet I have not till lately been able to place the subject in a satis- factory aspect, and to connect it with general laws, which givé a mathematical form to this fundamental branch of the science of polarization. If we consider a pencil of natural light as divided into two pencils polarized in rectangular planes by the action of a doubly refracting crystal, and conceive the light of these two pencils to return back through the crystal, it will obviously emerge in the state of natural light. When we examine the pencil thus tecomposed, or when we examine 4 pencil consisting of two oppositely polarized pencils superposed, we shall find that they comport themselves under every analysis exactly like common light ; so that we are entitled to assume such a pencil as the re- presentative of natural light, and to consider every thing that can be established respecting the one, as true respecting the other. NEW SERIES, VOL. III, NO. 1. JULY 1830. L 162 Dr Brewster on the law of the In applying this principle to the analysis of the phenomena produced by reflexion, I placed the ‘planes of polarization of the compound beam in the plane of reflexion ;* but though this led to some interesting conclusions, it did not develope any ge- neral law. I then conceived the idea of making the plane of reflexion bisect the right angle formed by the planes of polari- zation ; and in this way I observed a series of symmetrical ef- fects at different angles of incidence, which threw a broad -_ over the whole subject. In order to explain these results, let A, B, Plate I. (Fig. 5 .) represent the two pencils of oppositely polarized light as sepa- rated by double refraction ; let a 6, cd be the directions of their planes of polarization, forming a right angle ae c, and let the plane of reflexion MN, of a surface of plate glass, bisect the angle a éc, so that the planes a b,c d form angles of +45° and —45° with the plane M N.. Let a rhomb of calcareous spar have its principal section now placed in the plane of re- flection. At an incidence of 90°, reckoned from the perpendicular, the reflected images of A and B suffer no change, the angle ae is still a right angle, and the four pencils formed by the calca- reous spar are all of equal intensity. As the incidence, however, diminishes, the angle a ec diminishes also, and the ordinary and extraordinary images of A and B differ in intensity. At an incidence of 80° for example, the angle a ecis reduced from 90° to 66° ; at 70° it has been reduced to 40°, and at 56° 45’, the maximum polarizing angle, it has been reduced to 0°; that is, the planes of polarization a b, cd are now paraliel. .. Below the polarizing angle, at 50°, the axes are again inclined to each other, and form an angle of 22°.. At 40° they form an angle of 50°, and at.0°, or.a perpendicular incidence, they are again brought back to their primitive inclination of 90°. » Taking MN to represent the quadrant of incidence from 90° at M, to 0° at N, the curves, 90°, 0°, show the progressive change which takes place in the planes of polarization, the plane of polariza- tion being a tangent to the curve at the incidence which: cor- responds to any particular point of it. When we employ a surface of diamond in place oli =, the inclination of the axes a 6, ed is reduced to amie at ‘an inci- partial polarization of Light by reflewion. 163 dence of 80°, to 8° at an incidence of '70°, and at or 43° the axes become parallel. Such being the action of the afiening forces upon A and B taken separately, let us now consider them as superposed and forming natural light. At 90° and 0° of incidence, the reflecting force produces no change in the inclination of their axes or planes of polarization; but at 56° 45’ in the case of glass, and 67° 43’ in the case of diamond, the axes of all the particles are brought into a state of parallelism with the plane of reflection; and consequently when the image which they form is viewed by the rhomb of calcareous spar, they will all pass into the ordinary image, and thus prove that they are wholly polarized in the plane of reflection. All this is entirely conformable to what has been long known: but we now see that the total polarization of the reflected pen- cil at an angle whose tangent is the index of refraction, is ef- fected by turning round the planes of polarization of one-half of the light from right to left, and of the other half from left to right, each through an angle of 45°. Let us now see what takes place at those angles where the pencil is only partially polarized At 80° for example, the angle of the planes a 6, cd is 66°, that is, each plane of polarization has been turned round in opposite directions from an inclination of 45° to one of 33° with the plane of reflection. ‘The light has therefore suffered a physical change of a very marked kind, constituting now neither natural nor polarized light. It is not natural light, because its planes of polarization are not rectangular ; 3 itis not! polarized light, because they are not parallel. It is a pencil of light having the physical character of one-half of its rays: being polarized at an angle of 66° to the other half. It will now be asked, how a pencil thus characterized can exhibit the properties of a partially polarized pencil, that is, of a pencil part of whose light is polarized in the plane of reflexion, while the rest retains its condition of natural light. ‘This will be understood by replacing the analyzing rhomb with its principal section in the plane of reflexion, and viewing through it the images A and B at 80° of incidence. As the axis of A is in- clined 33° to M N or the section of the rhomb, the ordinary image of it will be much brighter than the extraordinary image 164 Dr Brewster on the law of the the intensity of each being in the ratio.of cos?9 to sin* 9, 9 be- ing the angle of inclination, or 33° in the present case. In like manner the ordinary image of B will be in the same. ratio brighter than its extraordinary image, that is, by considering A and B ina staté of superposition, the extraordinary image of a pencil of light reflected at 80° will be fainter than the or- dinary image in the ratio of sin °$3° to cos? 33°... But this in- equality in the intensity of the two pencils is precisely what would be produced by a compound pencil, part of which is polarized in the plane of reflexion, and part of which is common light. When Malus, therefore, and his successors analyzed the pencil reflected at 80°, they could not do otherwise than conclude that it was partially polarized, consisting partly. of light polarized in the plane of reflexion, and partly of natural light. The action of successive reflexions, however; afforded a more precise means of analysis, in so far as it proved that. the portion of what was deemed natural light had in reality stiffered a physical change, which approximated it to the state -of polarized light; and we now see that the portion of what was called polarized light was only what may be called appa- rently polarized 5 for deena it disappears, like polarized light, from the extraordinary image of the analysing prism, yet there is not a single particle of it polarized in the plane of reflexion. These results must be admitted. to possess considerable in- terest in themselves; but, as we shall proceed to shows, they lead to conclusions of general importance. The quantity of light which disappears from the extraordinary image, is, obyi- ously the quantity of light which is really or apparently pola- rized at the given angle of incidence; and if. we admit the truth of the law of repartition discovered by Malus, and repre- sented by Poo= Pocos?¢g, and Poe = Po sin? 9, and. if we can determine 9 for substances of every refractive powers and for all angles of incidence, we may consider as established the ma- thematical law which determines the intensity of the polarized pencil, whatever be the nature of the body which reflects it,— whatever be the angle at which it is incident,—whatever be the number of reflexions which it, suffers, and whether. these reflexions are all made from one substance, or partly from one substance and partly from another: partial polarization of Light by réflexion. 165 The first step in this investigation is to determine the law according to which a reflecting surface changes the plane of polarization of a polarized ray. This subject was first examin- ed by Malus, but not with that success which attended most of his labours. Before I was acquainted with what had been done by M. Fresnel, or with the experiments of M. Arago on glass and water, I had made a number of very careful experiments on the same subject, and had represented them by formule founded on the law of the tangents. These formule, however, I found to be defective; and I am persuaded, from a very cx- tensive series of experiments, that the formule of Fresnel are accurate expressions of the phenomena under every variation of incidence and refractive power. If ¢ is the angle of inci- dence, # the angle of refraction, 2 the primitive inclination of the plane of the polarized ray to the plane of reflexion, and’¢ the inclination to which that plane is brought by reflexion, Ries, according to Fresnel, we have cos (2 + 7) Tan ¢= tan . CH) When # is 45°,’ as in’ the’ preceding observations, then tang =], one we have ‘eos (¢ fv ’y. “Pan = cos (t= 2) as ~ In these: Scamiibel which are founded on the law of the tan- gents, i + @ is the supplement of the angle which ‘the refléct- ed ray forms with the refracted ray ; while i— 7 is the aiigle which the incident ray forms with the refracted ray, or the deviation produced by refraction. — These formule have been verified by M. Arago at ten an- gles of incidence upon glass, and four upon water ; but his experiments were made only in the case where wis 45°; and where tan # disappears from the formula. » As my expetiments embrace a wider range of substances, and also the general case where w varies from 0° to 90°, I consider them as a neces- sary basis for a law of such extensive application. The first series of experiments which I made was upon plate glass, in which the maximum polarizing angle was nearly 56°: hence I assume the index of refraction to be 1. rn The following were the results : 166 Angle of Incidence. 90° 88 86 84 80 75 70 65 60 56 50 45 40 30 20 10 Dr Brewster on the law of the Angle of Refraction. 0° 0° 42 23 42 17 42 8 41 37 40 40 39 20 37 41 35 45 34 0 31 22 28 29 25 42 19 43 13 20 6 44 Prate Gass, Inclination of Plane of Polari- . zation to Plane of Reflection. Observed. 45° OF 43 4 40 43 38 47 $3 138 28 45 22 6 14 40 6 10 0 0 9 O 16 55 22 37 32 25 39 O 44 0 Computed. 45° 0! 42 49 40 36 38 22 33 46 27 41 2) HE | (48°53 6 16 0 0 9 0 16 31 23 1 33 19 40 4 43 49 Difference. 0° 0’ 40 85 +0 7 +0 25 —0 33 414 418 +0 47 —0 6 0 0 0 0 +0 24 —0 24 —O0O 54 alhics & +011 These results, obtained in every part of the quadrant, com- pletely establish the accuracy of the formula. The differences are all within the limits of the errors of observation, and amount, at an average, to 323’ on each observation. In order to establish the accuracy of the formula for diffe- rent degrees of refractive power, I made the following experi- ments on diamond, in which the index of refraction was 2.440, Angle of Incidence. - 90°. 0’ 85 0 80. 0 75 0 70 O 67 43 60 0 50 0 Angle of Refraction. 24° 12" 24 6 23 48 . 23:19 22 39 22.17 20 47 18 18 DIaMonp. Inclination of Plane of Polari- zation to Plane of Reflexion. Observed. 45° 0/ 84 30 24 0 14 30 4 30 0 0 12 30 24 0 Calculated. 45° 0/ 33 56 23 12 13 8 3 54 0 0 11 41 23 30. Difference. 0° 0’ +0 34 +0 48 +1 22 +0 36° 0 0 +0 49° +0 30. partial polarization of Light by reflexion. 167 These differences, which at an average amount to 463’ ; are also within the limits of the errors of observation. — In‘all these experiments the value of 2 was 45°; but in order to determine the law of variation for 9, when # varies from 0° to 90°, I took a crystal of quartz with a fine natural surface parallel to its axis; and I found that at an angle of incidence of 75°, and when a was 45°, the inclination of the plane of polarization to the plane of reflexion was 26°20. I then varied x, and obtained the following results: | Inclination of Plane of Polarization. Values of z. = Ohier vale @ Calculated. Difference. 0° o° 0’ 0° 0’ | 0° 0’ 10 by 54 7 429 +0 25 20 i0 Oo 10 16 —0 16 30 15 50 16 2 —O0 12 35 20 0 * 4912 +0 48 40 23 30 22 40 +0 50 45 26 20 26 27 01:7 50 30 0 30. 40 —O6 40 55 35 30 35 23 $0.7 60. 40 0 40 45 —0 45 70 53 0 53 49 —0 49 80 TO. 0 70 29 —0 29 90 g0 0 90 0 0 0 In these experiments the average error does not exceed half a degree. The third’ column is computed by the formula tan 9 = (tan 26° 27’) tan a. From these experiments it appears that the formula expres- ses with great accuracy all the changes in the planes of po- larization which are produced by a single reflexion, and we may therefore apply it in our future investigations. Let us now suppose that a beam of common light composed of two portions A, B, (Plate I, Fig. 6.) polarized + 45° and — 45° to the plane of reflexion, is incident on a plate of glass at such an angle that the reflected pencil composed of C and D has its planes of polarization inclined at an angle ¢ to the plane MN. When a rhomb of calcareous spar has its principal sec- tion in the plane M N, it, will divide the image C into an ex: traordinary pencil E and an ordinary one F ; and the same will take place with D, G being its extraordinary and H its 168 Dr Brewster on the law of the ordinary image. If: we:represent ~~ whole of the reflected pencil or C + D by 1, then © = 3, D=}, E+ F =], and G +H=1. :But'since the planes of polarization of Cand D are each imchned'? degrees to the principal section. of the rhomb, the intensity of the light of the doubly refracted pen- cils will be as sin? 9: cos? 9; that is, the intensity of E will be § sin? g, and that of F, $ cos? 9. Hence it follews that the difference of these pencils, or } sin? g— } cos? 9, will ex- press the quantity of light which has passed from the extra- ordinary image E into the ordinary one.F, that is, the quan- tity of light apparently polarized in the plane‘of reflexion MN. But as the same is true of the pencil D, we have 2 (3 sin? g— $ cos? 9) or sin? 9 — cos” 9 for the whole of the polarized light in a pencil of common light C + D, Hence, since sin? 9 + cos? g = 1 and cos? g.= 1 — sin*® 9, we have for the whole quantity of polarized light Q=—1—2 sin’ ¢. cos (¢ + 7’) But Tan 9— tana os fant) sin’ 9 me And as Tan? 9 — cost g? and sin? g + cos?g = 1, we have the quotient and the sum of the quantities sin? g and cos? 9, by which we obtain (tana est y Sin? 9 ope (t=) Fora 1 es (tana bau sn che) +1 14+(tane psy eam a) (cn wv malted: Thatiis Qi Ve Q = TE ae (Gi)\? iin (‘an a ” 08 (i—7’) _ As the quantity of reflected light is here supposed to be 1, we may obtain an expression of Q in terms of the incident light by adopting the formula of Fresnel for the intensity of a re- flected ray. ~Thas sin? (i 4 tan®(7 — 7’) (meen - : anal an’(2— 2 a 53 me an icant tan*(i + =) ce any Gaien) cos(7-—’ partial polarization of Light by reflexion. 169 As tan # = 1 in common light,it is omitted in the preced- ing formula. This formula may be adapted to partially polarized. rays, that is, to light reflected at any angle different from the angle of maximum polarization, provided we can obtain an expres- sion for the quantity of reflected light. M. Fresnel’s general formula has been adapted to this spe- cies of rays, by considering them as consisting of a quantity a of light completely polarized in a plane making the angle with that of incidence, and of another quantity 1 —a in the state of natural light. Upon this principle it becomes gl sin? (? — 7’) (4 +acos? xz , tan? (i—7’) 1 — acos* x. = an? 4?) D tan? (Gj —7’) 2 But as we have proved that partially polarized rays are rays whose planes of polarization form an angle of 2. with one another as already explained, # being greater or less than 45°, we obtain a simpler expression for the intensity of the reflect- ed pencil, viz. the very same as that for polarized light. sink (Git L >gay 7 nega + Hence we have tan? (i — i’) tan? G7) sin? @ sin? (i — war» pad tan? (i — 7’) . iQ = Car G+ +P nat tan? wt ’) sin’ @ cos (2 + ») (1-2 (tana 3 :) of cos st ¢ ) I ( tan v ap) This formula is mde see to a single Ms, of po- larized light of the same intensity as the pencil of partially polarized light. In all these cases it expresses the quantity of light really or apparently polarized in the plane of reflexion, In order to show the quantity of light polarized at differ- ent angles of incidence, I haye computed the following table for common bght, and suited to glass in which m = 1.525, 170 - Dr Brewster on the law. of the PuLatvEe GLaAss. > " Inclination of ne : , ‘Angle of Angleof’ Plane of Pola- yvn¢ reifcct- Quantity of Ratio of Po- Incidence. Refrac-. rization to ed out of 1000 Polarized Reflected — i. ion. 7’ ane of Re- ;, i f . i tion. 7 Smit Rays. Light Q Ke " 00.00 45.0 ‘48.23 0 ree 10.0, 632 43 51 43.39 1.74. 0.04000 . 20. 0. 12 58 40 18 43.41 7-22. 0.16618 25.0 16°5. 87 21 43.64 116 0.26388 30 0 19 8} 33 40 44.78 17.25 0.8853” 35 0°22 6 ° 29 °8 46.33 . 24.87) 0.5260 40 0. 2456 © 23 41 49.10 33.25) ».0.6773 45° 0° 27-375 17 223 53.66 44.09 | 0.82167 50 0 30 9 10 18 61.36 7.36 0.9360 56 45° 33 15 00} 79-5 79.5 1.000 - 60 0 34°36 5 4 93.31 91.6. . 0.9628 65 0. 3628 12 45 124.86. 112.7 0.90258. 70 0 38 2 18 32 162.67 129.80 0.79794 75 0 3918 26 52 257.26 152.34 0.59154 " 78 0 39.54 980) 44 329.95 157.67. 0.47786 79 0 40 4: 381, 59 359.27 157.69 0.43892 80 0 4098 . 83.18. +> "89.7 156.6 0.40000 82 44 40 35 86 22 499.44 145.4 0.29112. 84 0 40 42 $8 2 560.32 134.93 02408 85 0 4047 39 12 616.28 - 123.75 0.2008 86 O° 4051 40 22.7 676.26 108.67 0.16068 87 O 40 54 41 32 744.11 89.83 0.12072 88 0 4057, 42 42 819.9 65.9 0.0804 89 0 40 58 43 61 904.81 36.32 0.04014 90 0 4058... 45 0 1000.0 0 0.0000 As the preceding formula is deduced from principles which have been either established by experiment or confirmed by it, it may be expected to harmonize with the results of obser- vation. At all the limits where the pencil is either wholly po- larized or not polarized at all, it of course corresponds with experiment: but though in so far as I know there have been no absolute measures taken of the quantity of polarized light at different incidences, yet we are fortunately in possession of a set of experiments by M. Arago, who has ascertained the angles above and below the polarizing angle at which glass and water polarize the same proportion of light. In no case has he measured the absolute quantity of the polarized rays; but the comparison of the values of Q at those angles at which he partial polarization of Light by reflexion. 171 found them in equal proportions, will afford a test of the ac- curacy of the formula. This comparison is shown in the fol- lowing table, in which col. 1, contains the angles at which the reflecting surface polarizes equal proportions of light ; col. 2, the values of 9 or the inclination of the planes of polarization ; and col. 3, the intensities of the polarized light computed from the formula. Angles of. Inclination of planes Proportion of Incidence z. _ of polarization te M N, polarized light | ‘OF @. or Q. " ¢ 99°39" 37° 33’ .2572 Glass: No. 1. 24 18 37 21 .2637 Rilingieny ge oy 36 47 2828 O. & 6 6 36 0 .3090 "8 20 32 38 4186 No. 3. 29 42 $3 1 -4064 . 86 31 41 54 1080 Water: No. 4. 16 12 41 27 1236 ~The agreement of the formula with experiments made with as great accuracy as the subject will admit must be allowed to be very satisfactory. The differences are within the limits of - the errors of observation, as appears from the following table : Deviations from — Part of the Experiment. whole light. Glass: No.1. 0.0065 tic No. 2. 0.0262 as No. 3. 0.0122 oe Water: No. 4. 0.0156 Air! & M. Arago has concluded, from the experiments above ‘stated, that equal proportions of light are polarized at equal angular distances from the angle of complete polarization. Thus in glass No. 1. the mean of 82° 48’ and 24° 18’ is 53° 33’, which does not differ widely from the maximum polarizing angle, or 55°, which M. Arago considers as the maximum polarizing angle of the glass.* \ In order to compare this’ principle with the formula, I found that in water No. 4. the angle which po- larizes almost exactly the same proportion of light as the angle “ Hence we have assumed m = 1,428, the tangent of 55°, in the pre- ceding calculations. | 172 Dr Brewster on the law of the of 86° 31’, is 15° 10’, the value ofg being 41° 54 at both these angles ; but’ the mean of these is 50° 50’ in place of 53° 11’; so that the rule of M. Arago cannot be regarded as cor- rect, and cannot therefore be employed, as he proposes, to de- termine the angle of complete polarization. mh The application of the law of intensity to the phenomena of the polarization of light by successive reflexions, forms a most interesting subject of research. No person, so far as I know, has made a single experiment upon this point, and those which I have recorded in the Philosophical, Transactions for 1815, have, I believe, never been repeated. ‘All my fellow labourers, indeed, have overlooked them as insignificant, and have eyen pronounced the results which flow from them to be chimerical and unfounded. Those immutable truths, how- ever, which rest on experiment, must ultimately have their triumph ; and it is with no slight satisfaction, that, after fif- teen years of unremitted labour, I am enabled not only to de- monstrate the correctness of my former experiments, but to present them as the necessary and calculable results of a gene- ral law. When a pencil of common light has been reflected from a transparent surface, at an angle of 61° 3’ for example, it has experienced such a physical change, that its planes of pola- rization form an angle of 6° 45’ each with the plane of re- flexion. When it is incident on another-similar surface at the same angle, it is no longer common light in which # = 45°, but .it is partially polarized light in which # = 6° 45’. In computing, therefore, the effect of the second reflexion, we must take the general formula tan 9 = tan We . a 3 i but, as the value of & is always in the same ratio to the value of 2, however great be the number of: reflexions, we have tan 4 — tan” 9 for the.inclination ¢ to the plane of reflexion pro- duced by. any number. of reflexions ”, 9 being the inclination for one reflexion, _ Hence when 4 is given by observation, we wf) have tan 9/0, d. The formula for any 1 number n, of reflexions * It is obvious that the rule can only be true when m = 1, 000 5 so that its error increases with the refractive power. partial polarization of Light by reflexion. 173 oe ' . cos (i + 7)\% : WANE is therefore tan 9 = ( —. eas . It is evident that @ never can become equal to 0°; that is, that the pencil cannot be so completely polarized by any number of reflexions at angles different from the polarizing angle, as it is by a single re- flexion at the polarizing angle ; but we shall see that the pot larization is sensibly complete in consequence of the near ap~. proximation of # to 0°. I found, for example, that light was polarized by two re- flections from glass at an angle of 61° 3’, and 60° 28’ by ano. ther observation. Now in these cases we have G after Ist @after2d Quantity of Un- Reflexion. Reflexion. polarized Light. Two reflexions at 61° 3’ 6° 45’ 0° 47 0.00037 60 28 5 38 0 88 0.00018 The quantity of unpolarized light is here so small as to be quite inappreciable with ordinary lights. In like manner I found that light was completely polarized by five reflexions at 70°. Hence by the formula we have Values of 6. Unpolarized Light. 1 reflexion at '70° 20° 0’ 0.23392 . 2 A - - 7% 82 0.03432 3 - - - » 245 0.00460 + X é r . 1 O 0.00060 5 a 2 us = 0 22 0.00008 The quantity of unpolarized light is hete also unappreciable after the fifth reflexion. In another experiment I found that light was wholly pola- rized by the separating surface of glass and water at the follow- ing angles : Values of 8. Unpolarized Light. By 2 reflexions at 44° 51/ 056 0.0005 By3) 2 4. 42:27 0 26 0.0001 In all these cases the successive reflexions were made at the same angle; but the formula is equally applicable to reflexions at different angles,— 1. When both theanglesare greater than the polarizing angle. Unpolarized 6 Light. 1 reflexion at 58° 2’, and 1 at 67° 2’ 0°34 0,0002 174 Dr Brewster-on the law of the © - 2. When. one of the angles is above and the other below the polarizing angle. ¥ Unpolarized — g Light. 1 reflexion at 53°, and | at 58° 2 012% 0.000024 This experiment requires a very intense light, for I find in my journal that the light of a candle is polarized at 53° and 78°. In reflexions at different angles, the formula becomes tan pa oeet x — 7 “ ie I and ¢ being the angles ofincidence. In like manner if a, 6, ¢, d, e, &c. are the values. of g or ¢ for each reflexion, or rather for each angle of inci- dence, we shall have the final angle or tan @ = (tan @ X tan b) + (tan c.x tan d,) &e. It is scarcely necessary to inform the reader that when a pencil of light reflected at 58° 2’ is said to be polarized by an- other reflexion at 67° 2’, it only means, that this is the angle at which complete polarization takes place in diminishing the angle gradually from 90° to 67° 2’, and that even this angle of 67° 2’ will vary with the intensity of the original pencil, with the opening of the pupil, and with the sensibility of the retina. But when it shall be determined experimentally at what value of 9, or rather at what value of Q, the light entirely disappears from the extraordinary image, we shall be able by inverting the formula to ascertain the exact number of reflexions by which a given pencil of light ‘shall. be wholly polarized. As the value of Q depends on the relation of é to 7’, that is, on the index of refraction, and as this index varies for the different colours of the spectrum, it is obvious that Q will have different values for these different colours. The consequence of this must be, that in bodies of high dispersive power the unpolarized light which remains in the extraordinary image, and also the light which forms the ordinary image, must be coloured at all incidences; the colours being most distinct near the maximum polarizing angle. This necessary result of the formula, I found to be experimentally true in oil of cassia, and. various highly dispersive bodies. In realgar for example ¢ is — 0 at an angle of 69° 0’ for blue light, at 68° 37’ for green light, and at 66° 49/ for red light. Hence there can be no angle of complete’ polarization for white light, which I also partial polarization of Light by reflexion. 175 found to be the case* by experiment; and as Q must’at diffe- rent angles of incidence have different values for the different rays, the unpolarized light must be composed of a certain por- _ tionof each different colour, which may be easily determined by the formula. Such are the laws which regulate the pbberisatioh of light _ by reflexion from the first surfaces of bodies that are not me- tallic. The very same laws are applicable to their second sur- faces, provided that the incident light has not suffered previous or subsequent refraction from the first surface. The sine of the angle at which ¢ or Q has a certain value by reflection from the second surface, is to the sine of the angle at which they have the same value at the first surface, as unity is to the index of refraction. Hence g and Q may be determined by the preceding formulee after any number of reflexions, even if some of the reflexions are made from the first surface of one body and the second surface of another. When the second surface is that of a plate with parallel or inclined faces, its action upon light presents curious phenome- na; the law of which I have determined. TI refer of course to the action of the second surface at angles less than that which produces total reflexion. This action has hitherto remained uninvestigated. It has been hastily inferred, however; from imperfect data ; and the erroneous inference forms the basis of some optical laws, which are considered to be fully esta- blished. Among ‘the various results of the preceding investigation, there is one which seems to possess some theoretical importance. If we consider polarized rays as those whose planes of polari- zation are parallel, then it follows that light cannot be brought into such a state by any number of reflexions, or at any angle of incidence, excepting at the angle of complete polarization. Atall other angles the light which seems to be polarized, by disappearing from the extraordinary image of the analysing rhomb, is distinguished from really polarized light, by the pro- perty of its planes of polarization forming an angle with each other and with the plane of reflexion. At the polarizing angle, for example, of 56° 45/ in glass, the light reflected is 79.5 rays, and it is completely polarized, because the planes of polariza- 176 . Dr Brewster 6n the law of the tion of all the rays are parallel ; but_at an angle of incidence of 80°, where 392 rays are reflected, no fewer than 157 appear to be polarized, though their planes of polarization are inclin- ed 66° 26’ to each other, or 33° 12’ to the plane of reflexion, This appearance of polarization, when the rays have only suf- fered a displacement in their planes of polarization from an angle of 90°; which approximates them to the state of polariz- ed light, arises from the law which regulates the repartition of polarized light between the ordinary and extraordinary images produced by double refraction, and shows that the analysing crystal is not sufficient to distinguish light completely polarize éd from light in a state of approach to polarization. The dif- ference, however, between these two kinds of light is marked by most distinctive characters, and will be found to show itself in some of the more complex phenomena of interference, In my paper of 1815, already referred to, I was led by a distant view of the phenomena which I have now developed, to consider common light as composed of rays in every state of positive and negative polarization ;* and upon this principle the whole of the phenomena described in this paper may be ¢alcue lated with the same exactness as upon the supposition of two oppositely polarized pencils. Nothing indeed can be simpler than such a principle. .The particles of) light have planes, which are acted upon by the attractive and repulsive forces re- siding in solid bodies; and as these planes must have every possible inclination to a plane passing through the direction of their motion, one-half of them will be inclined — to this plane, and the other half +. When light.in such a state falls upon a reflecting surface, the — and the 4+ particles have each their planes of polarization brought more or less into a state of paral- lelism with the plane of reflexion, in consequence of the action of the repulsive force upon one side or pole of the partiéle through which the plane passes; while in the particles which suffer refraction, the same sides or poles are by the action of the attractive force drawn downwards, so as to increase the in- clination of their aie relative to the plane of incidchee, am © Riot thes Followed ame, in, cis opinion. See Traité de Pigvie, m- iv. p. 304. ) _ Sir H. Davy’s Consolations,in Travel. 177 bring them more or less into a state of parallelism with a plane perpendicular to that of refraction. The formule already given, and those for refracted light which are contained in another paper, represent the laws ac- cording to which the repulsive and attractive forces change the position of the: planes of polarization; and as we, have proved that the polarization is the necessary consequence of these planes being brought into certain positions, we may re- gard all the various phenomena of the polarization of light by reflexion and refraction, as brought under the dominion of laws as well determined as those which regulate the motions of the planets. | _ ALLERLY; December 25, 1829. Ant. XIX.—ANALYSIS OF SCIENTIFIC BOOKS. AND ME- MOIRS. Consolations. in Travel, or the Last Days uf a Philosopher. By Sir _ Humpury Davy, Bart. late President of the Royal Society. London, 1830. 12mo. . Pp. 281. , . T urs little volume, of which we propose to give some account, is the last production of a philosopher whose brilliant discoveries piaced him at the head of chemical science. However exalted .be the genius of some of his contemporaries, and however numerous their discoveries, yet Sir Humph- ry Davy must be allowed to be the Newton of chemistry, and to have sus- tained the scientific glory of England during his short but illustrious ca- reer. With him, and with his two great associates, Dr Wollaston and Dr Young, that glory has departed ; and if the nation and the government are “not speedily roused from their indifference, we may live to witness the in- tellectual degradation of England, and to see her science, her philosophy, and her arts, transported to other lands, and directed against the very vitals of her existence.’ © When Sir Humphry Davy was compelled from ill health to resign the Presidency of the Royal.Society, and to ubandon those mental exertions which the prosecution of original discovery demanded, the native activity of his mind was directed into other channels of thought less. severe upon his debilitated frame, and perhaps. more congenial to a mind looking for-. ward to its great deliverance. During his partial recovery from a long and dangerous illness he composed his Salmonia, a treatise on angling, inter- spersed with moral and religious reflections, and adorned with many .inte- resting scientific discoveries of a popular character. The work now under our eye was composed immediately after, under the same unfavourable and painful circumstances, and at a period, as he himself remarks, when. the constitution of the author suffered from new attacks. . When most other NEW SERIES, VOL. III. No. 1. JULY 1830. M 178 Analysis of Scientific Books and Memoirs.. sources of consolation and pleasure'weére'closed to him, he derived a share of both from this exercise of his mind. It was céncladed at the very moment of the invasion of his last illness, and it is probable, as the editor observes, that some additions and some changes would have been made had he lived. The Consolations in Travel consists of Six Dialogues. 1. The Vision. 2. Discussions connected with thé Vision in the Coloseum. 3. The Un- known. 4. The Proteus‘or Immortality. 5. 'The Chemical Philosopher. And 6. Pola or Time: t In. the first of these dialogues. our author gives an account of a vision which he is supposed: to:-have seen while contemplating the ruins of the Coloseum. A spectral being is supposed to appear, and lays before him @ brief view of the’ various states of society from the earliest to the present times. He is then’ ¢arried up into the Heavens, and has his attention’ di- rected to the region of Saturn, whose inhabitants are described as beings possessing organs and powers far more extensive than those of man, which give them an insight into the structure of the universe of which we can form no conception. The first part of the vision is extremely interesting, and will be read with great interest even by those who are best acquainted — with the various topics to which it refers ; but the latter part of the vision is so completely the work of imagination, and so thoroughly devoid of all probability, that we forbear making any extract from it. dain In the third dialogue, called the Unknown, the author and his friends meet at the Ruins of Pestum with a stranger, who conveys to them much curious information respecting the natural history of the country. The following extract, somewhat abridged, relative to the Lake of Solfatard, will be read with great interest :— | « Ambrosio now came forward, and bowing to the stranger, asked hint _whether the masses of travertine, of which the Cyclopian walls and the temples were formed, were really produced by aqueous deposition from thé river Silaro, as he had often heard reported. The stranger’ replied ;— ‘ that they were certainly produced by deposition from water ; and such deposits are made by the Silaro. But I rather believe, he said, that a lake in the immediate neighbourhood of the city furnished the quarry from which these stones were excavated ; and if you like, I will accompany you to the spot from which it is evident that large masses of the travertine; marmor tiburtinum or calcareous tufa have been raised.’ We walked to the borders of a lake, on a mass of calcareous tufa, and we saw that this substance had even encrusted the reeds on the shore. There was some- thing peculiarly melancholy in the character of this water ; all the herbs around it were grey, as if encrusted with marble. ‘ There,’ said the stranger, ‘ is, what I believe to be, the source of those large and durable stones which you see in the plain before you. ‘This water rapidly deposits calcareous matter, and even if you throw a stick into it, a few hours is sufficient to give it a coating of this substance. Whichever way you turn your eyes you see masses of this recently produced marble, the conse- quence of the overflowing of the lake during the winter floods, and in that large excavation you may observe that immense masses have been removed, as if by the hand of art and in remote times ;—the marble that remains Sir H. Davy’s Consolations in Travel. 179 in the quarry is of the same texture and character as that which you see in the ruins of Pestum, and I think, it is scarcely possible to doubt, that the builders of those extraordinary structures derived a part of their ma- terials from this spot.’ This water is like many, I may say, most of the sources which rise at the foot of the Appennines; it holds carbonic acid in solution which has dissolved a portion of the calcareous matter of the rock through which it has passed ;—this carbonic acid is dissipated in the atmosphere, and the marble, slowly thrown down, assumes a crystalline form and produces coherent stones. The lake before us is not particularly rich in the quantity of calcareous matter that it contains, for, as I have found by experience, a pint of it does not afford more than five or six grains ; but the quantity of fluid and the length of time are sufficient to account for the immense quantities of tufa and rock which in the course of ages have accumulated in this situation. It can, I think, be scarcely doubted that there is a source of volcanic fire at no great distance from the surface, in the whole of southern Italy ; and, this fire acting upon the cal- careous rocks of which the Appeunines are composed, must constantly de- tach from them carbonic acid, which rising to the sources of the springs, deposited from the waters of the atmosphere, must give them their im- pregnation and enable them to dissolve calcareous matter. I need not dwell upon Etna, Vesuvius, or the Lipari islands to prove that volcanic fires are still in existence ; and, there can be no doubt, that in earlier pe- riods almost the whole of Italy was ravaged by them; even ‘Rome itself, the eternal city, rests upon the craters of extinct volcanos; and, I ima- gine that the traditional and fabulous record of the destruction made by the conflagration of Phaeton, in the chariot of the sun, and his falling into the Po, had reference to a great and tremendous igneous volcanic eruption, which extended over Italy and ceased only near the Po at the foot of the Alps. Be this as it may, the sources of carbonic acid are numerous, not merely in the Neapolitan but likewise in the Roman and Tuscan states. The most magnificent waterfall in Europe, that of the Velino near Terni, is partly fed by a stream containing calcareous matter dissolved by carbonic acid, and it deposits marble, which crystallizes, even in the midst of its thundering descent and foam, in the bed in which it falls: The Anio or Teverone, which almost approaches in beauty to the Velino in the num- ber and variety of its falls and cascatelle, is likewise a calcareous water ; and there is still a more remarkable one which empties itself into this river below Tivoli, called the lacus Albula, or the lake of the Solfatara. Besides the lake, where the ancient Romans erected their baths, there is another a few yards above it, surrounded by very high rushes and almost hidden by them from the sight. This lake sends down a considerable stream of tepid water to the larger lake, but this water is less strongly ini- pregnated with carbonic acid; the largest lake is actually a saturated so- lution of this gas, which escapes from it in such quantities in some parts of its surface that it has the appearance of being actually in ebullition: I have found by experiment that the water taken from the most tranquil part of the lake, even after being agitated and exposed to the air, contain- ed in solution more than its own volume of carbonic acid gas with a very 180 Analysis of Scientific Books and Memoirs. small quantity of sulphuretted hydrogen, totthe presence of which, I con- clude, its ancient use in curing cutaneous disorders may be referred. Its temperature, I ascertained, was in the winter in the warmest parts above 80° of Fahrenheit, and it appears to be pretty constant, for I have found it differ a few degrees only in the ascending source, in January, March, May, and the beginning of June; it is therefore supplied. with heat from a subterraneous source, being nearly twenty degrees above the mean tem- perature of the atmosphere. Kircher has detailed in his Mundus Subter- raneus various wonders respecting this lake, most of which are unfounded, such as that it is unfathomable, that it has at the bottom the heat of boil- ing water, and that floating islands rise from the gulf which emits its. It must certainly be very difficult, or even impossible to fathom a source which rises with so much violence from a subterraneous excavation ; and, © at a time when chemistry had made small progress, it was easy to mistake the disengagement of carbonic acid for an actual ebullition. ‘The floating islands are real, but neither the Jesuit nor any of the writers who have since described this lake, had a correct idea of their origin, which is ex- ceedingly curious. The high temperature of this water, and the quantity of carbonic acid that it contains, render it peculiarly fitted to afford a pabulum or nourishment to vegetable life; the banks of travertine are every where covered with reeds, lichens, conferve, and various kinds of aquatic vegetables ; and, at the same time that the process of vegetable life is going on, the crystallizations of the calcareous matter, which is every where deposited in consequence of the escape of carbonic acid, like- wise proceed, giving a constant milkiness to what from its tint would otherwise be a blue fluid. So rapid is the vegetation, owing to the decom- position of the carbonic acid, that even in winter, masses of confervee and lichens, mixed with deposited travertine, are constantly detached by the currents of water from the bank, and float down the stream, which being a considerable river, is never without many of these small islands on its surface ; they are sometimes only a few inches in size, and composed merely of dark-green conferve or purple or yellow lichens, but they are sometimes even of some feet in diameter, and contain seeds and various species of common water-plants, which are usually more or less incrusted with - marble. There is, I believe, no place in the world, where there is a more striking example of the opposition or. contrast of the laws of animate and inanimate nature, of the forces of inorganic chemical affinity and those of the powers of life. Vegetables, in such a temperature and every where surrounded by food, are produced with a wonderful rapidity ; but the crystallizations are formed with equal quickness, and they are no sooner produced than they are destroyed together. Notwithstanding the sulphu- reous exhalations from the lake, the quantity of vegetable matter genera- ted there and its heat make it the resort of an infinite variety of insect tribes ; and ‘even in the coldest days in winter, numbers of flies may be observed on the vegetables surrounding its banks or on its floating islands, and a quantity of their larve may be seen there, sometimes incrusted and entirely destroyed by calcareous matter, which is likewise often the fate of the insects themselves, as well as of various species of shell-fish that are _ Sir H. Davy’s Consolations in Travel. 181: found amongst the vegetables, which grow and are destroyed in the tra- vertine on its banks. Snipes, ducks, and various water-birds often visit these lakes, probably attracted by the temperature and the quantity of food in which they abound ; but they usually confine themselves to the banks, as the carbonic acid disengaged from the surface would be fatal to them, if they ventured to swim upon it when tranquil. In May 18—I fixed a stick on a mass of travertine covered by the water, and I examin- ed it in the beginning of the April following, for the purpose of deter- mining the nature of the depositions. ‘The water was lower at this time, yet I had some difficulty, by means of a sharp-pointed hammer, in breaking the mass which adhered to the bottom of the stick ; it was se- veral inches in thickness. The upper part was a mixture of light. tufa and the leaves of conferve ; below this, was a darker and more solid tra- vertine, containing black and decomposed masses of conferve ; in the in- ferior part, the travertine was more solid and of a grey colour, but with cavities which I have no doubt were produced by the decomposition of ves. getable matter. I have passed many hours, I may say, many days, in studying the phenomena of this wonderful lake; it has brought many trains of thought into my mind connected with the early changes of our globe, and I have sometimes reasoned from the forms of plants and animals preserved in marble in this warm source, to the grander depositions in the secondary rocks, where the zoophytes or coral insects have worked upon a grand scale, and where palms and vegetables now unknown, are preserved with the remains of crocodiles, turtles and gigantic extinct ani- mals of the sauri genus, and which appear to have belonged to a period when the whole globe possessed a much higher temperature. I have like- wise often been led from the remarkable phenomena surrounding me in that spot, to compare the works of man with those of nature. The baths, erected there nearly twenty centuries ago, present only heaps of ruins, and even the bricks of which they were built, though hardened by fire, are crumbled into dust, whilst the masses of travertine around it, though formed by a.variable source from the most perishable materials, have har-. dened by time, and the most perfect remains of the greatest ruins in the eternal city, such as the triumphal arches and the Coloseum, owe their duration to this source. Then, from all we know, this lake, except in some change in its dimensions, continues nearly in the same state in which it was described 1700 years ago by Pliny, and I have no doubt contains the same kinds of floating islands, the same plants and the same insects. During the fifteen years that I have known it, it has appeared precisely identical in these respects ;—and yet, it has the character of an accidental phenomenon depending upon subterraneous fire. How marvellous then are those laws by which even the humblest types of organic existence are pre- served though born amidst the sources of their destruction, and by which a species of immortality is given to generations floating, as it were, like evanescent bubbles, on a stream raised from the deepest caverns of the earth, and instantly losing what may be called its spirit in the atmo- sphere.” - The next extract which we shall submit to our readers relates to the in- 182 Analysis of Scientific Books and Memoirs. fluence of time in producing changes ia the material world, After giving: an aecount of the influence of gravitation in producing alterations on the surface of the earth, our author proceeds to consider the chemical changes which are produced ; and under this head he considers, first, the chemical agency of water, then that of air, and, lastly, that of electricity, “‘ One of the most distinet and destructive agencies of water depends upon its solvent powers, which are usually greatest when its temperature is highest. Water is capable of dissolving, in larger or smaller proportions, most compound bodies, and the calcareous and alkaline elements of stones are particularly liable to this kind of operation. When water holds in so- lution carbonic acid, which is always the case when it is precipitated from the atmosphere, its power of dissolving carbonate of lime is very rauch in= creased, and in the neighbourhood of great cities, where the atmosphere. contains a large proportion of this principle, the solvent powers of rain. upon the marble exposed to it must be greatest. Whoever examines the marble statues in the British Museum, which have been remoyed from. the exterior of the Parthenon, will be convinced that they have suffered from this agency ; and an effect distinct in the pure atmosphere and tem-. perate climate of Athens, must be upon a higher scale in the vicinity of other great European cities, where the consumption of fuel produces car- bonic acid in large quantities. Metallic substances, such as iron, copper, bronze, brass, tin and lead, whether they exist in stones, or are used for support or connexion in buildings, are liable to be corroded by water hold- ing in solution the principles of the atmosphere ; and the rust and corro= sion, which are made, poetically, qualities of time, depend upon. the oxy- dating powers of water, which by supplying oxygen in a dissolved or con- densed state enables the metals to form new combinations. All the vege~ table substances, exposed to water and air, are liable to decay, and even the vapour in the air attracted by wood, gradually reacts upon its fibres. and assists decomposition, or enables its elements to take new arrangements... Hence it is that none of the roofs of ancient buildings more than 1000, years old remain, unless it be such as are constructed of stone, as those of: the Pantheon of Rome and the tomb of Theodorie at Ravenna, the cupola of which is composed of a single block of marble. The pictures of the. Greek. masters, which were painted on the wood of the abies, or pine of the Mediterranean, likewise, as we are informed by Pliny, owed their de- reous ground on which they were painted, but to the decay of the tablets. of wood on which the intonaco or stucco was laid. Amongst the sub- stances employed in building, wood, iron, tin and lead are most liable to decay from the operation of water, then marble, when exposed. to its in-. fluence in the fluid form ; brass, copper, granite, sienite and porphyry are, more durable. But, in stones, much depends upon the peculiar nature of their constituent parts; when the feldspar of the granite rocks, contains, little alkali or calcareous earth, it is a very permanent stone ; but, when in granite, porphyry or sienite, either the feldspar contains much alkaline matter, or the mica, schorl or hornblende much protoxide of iron, the ac-. tion of water, containing oxygen and carbonic acid, on the ferruginous ele- x _ Sir H, Davy’s Consolations in, Pravel. 183 ments tends to produce the disintegration of the stone. The red granite, black sienite and red porphyry of Egypt, which are seen at Rome in obe~ lisks, columns and sarcophagi are amongst the most durable compound stones ; but, the grey granites of Corsica and Elba are extremely liable to undergo alteration,—the feldspar contains much alkaline matter and the mica and schorl much protoxide of iron. A remarkable instance of the decay of granite may be seen in the hanging tower of Pisa; whilst the marble pillars in the basement remain scarcely altered, the granite ones have lost a considerable portionof their surface, which falls off continually in scales, and exhibits every where stains from the formation of peroxide of iron. The kaolin, or clay, used in most countries for the manufacture - of fine porcelain or china, is generally produced from the feldspar of de- composing granite, in which the cause of decay is the dissolution and se- aration of the alkaline ingredients. ‘* There are few compound stones, possessing a considerable specific gra- wity, which are not liable to change from this cause ; and oxide of iron amongst the metallic substances anciently known, is the most generally dif- fused in nature, and most concerned in the changes which take place on the surface of the globe. The chemical action of carbonic acid, is so much connected with that of water, that it is scarcely possible to speak of them separately, as must be evident from what I have before said ; but the same action which is exerted by the acid dissolved in water is likewise exerted by it in its elastic state, and in this case the facility with which the quan- tity is changed makes up for the difference of the degree of condensation. There.is no reason to believe that the azote of the atmosphere has any con- siderable action in producing changes of the nature we are studying on the surface; the aqueous vapour, the oxygen and the carbonic acid gas, are, however, constantly in combined activity, and above all the oxygen. And, whilst water, uniting its effects with those of carbonic acid, tends to disin- tegrate the parts of stones, the oxygen acts upon vegetable matter. And, this great chemical agent, is at once necessary, in all the processes of life and in all those.of decay, in which nature, as it were, takes again to her- self those instruments, organs and powers, which had for a while been bor- rowed and employed for the purpose or the wants of the living principle. Almost,every thing effected by rapid combinations in combustion, may also be effected gradually by the slow absorption of oxygen; and though the productions of the animal and vegetable kingdom are much more submit- ted to the power of atmospheric agents than those of the mineral kingdom, yet, as in the instances which haye just been mentioned, oxygen gradually destroys the equilibrium of the elements of stones and tends to reduce into powder, to render fit for soils,,even the hardest aggregates belonging to our globe. Electricity, as a chemical agent, may be considered, not only as directly producing an infinite variety of changes, | but likewise as influ- encing almost all which take place. ‘There are not two substances on the surface of the globe, that are not indifferent electrical relations to each other ; and; chemical attraction itself seems to be a peculiar form of the exhibi- tion of electrical attraction ; and, wherever the atmosphere, or water, or any part of thesurfaceof theearth gainsaccumulated electricity of adifferent kind 184° Analysis of Scientific Books and Memoirs. from the contiguous surfaces, the tendency ofthis electricity is to produce new arrangements of the parts of these surfaces ; thus, a positively electri- fied cloud, acting even at a great distance on a moistened stone, tends to attract its oxygeneous or acidiform or acid ingredients, and, a negatively electrified cloud has the same effect upon its earthy, alkaline, or metallic matter ;—and the silent and slow operation of electricity is much more important in the economy of nature than its grand and impressive opera- tion in lightning and thunder. The chemical agencies of water and air, are assisted by those of electricity ; and their joint effects combined with those of gravitation and the mechanical ones I first described, are sufficient to account for the results of time. But, the physical powers of nature in producing decay, are assisted likewise by certain agencies or energies of or= ganised beings. A polished surface of'a building, or a statue, is no sooner made rough from the causes that have been mentioned, than the seeds of lichens and mosses, which are constantly floating in our atmosphere, make it a place of repose, grow and increase, and from their death, their decay and decomposition carbonaceous matter is produced, and at length a soil is formed, in which grass can fix its roots. In the crevices of walls, where this soil is washed down, even the seeds of trees grow, and, gradually as a building becomes more ruined, ivy and other parasitical plants cover it. Even the animal creation lends its aid in the process of destruction, when man no longer labours for the conservation of his works. The fox burrows amongst ruins, bats and birds nestle in the cavities in walls, the snake and the lizard likewise make them their habitation. Insects act upon a smal- - ler scaie, but by their united energies sometimes produce great effect ; the ant, by establishing her colony and forming her magazines, often saps the foundations of the strongest buildings, and the most insignificant creatures triumph as it were over the grandest works of man. Add, to these sure and slow operations, the devastations of war, the effects of the destructive zeal of bigotry, the predatory fury of barbarians seeking for concealed wealth under the foundations of buildings and tearing from them every metallic substance,—and it is rather to be wondered, that any of the — of the great nations of antiquity are still in existence. ; ‘* The operations of nature, when slow, are no less sure ; however man may for a time, usurp dominion over her, she is certain of recovering her empire. He converts her rocks, her stones, her trees into forms of palaces, houses, and ships ; he employs the metals found in the bosom of the earth as instruments of power, and the sands and clays which constitute its sur- face as ornaments and resources of luxury ; he imprisons air by water, and tortures water by fire to change or modify or destroy the natural forms of things. But in some lustrums his works begin to change, and in a few centuries they decay and are in ruins; and, his mighty temples, framed as it were for immortal and divine purposes, and his bridges formed of gra- nite and ribbed with iron, and his walls for defence, and the spleadid monuments by which he has endeavoured to give eternity even to his perishable remains, are gradually destroyed ; and these structures, which have resisted the waves of the ocean, the tempests of the sky and the stroke of the lightning, shall yield to the operation of the dews of Heaven, of Sir H. Davy’s Consolations in Travel. 185 frost, rain,:-vapour and imperceptible atmospheric influences ; and, as the worm devours the lineaments of his mortal beauty, so the lichens and the moss, and the most insignificant plants shall feed upon his columns and his pyramids, and the most humble and insignificant insects shall under- mine and sap the foundations of his colossal works, and make their habita- tions amongst the ruins of his palaces and the falling seats of his earthly glory.” Throughout the whole of this interesting volume, we observe traces of the most genuine and unaffected piety, and the most complete proofs, that the author had studied, in his latter days at least, the peculiar doctrines of Christianity, and derived from them that consolation which they are so well fitted toinspire. It isa proud triumph of the Christian faith, that the great- estchemical philosopher of modern times, should not only have addedhistes- - timony to its truth, but should have spent his latest hour in impressing his convictions upon others. There perhaps never was an individual who rose more quickly than Sir H. Davy to the highest objects of ambition. Placed in the chair of Newton, at the head of the Royal Society, honoured by the special notice of his sovereign, associated with the highest ranks of society, and distinguished over all Europe, as the most successful of modern inquir- ers, he yet found that there was something beyond all this, after which his soul aspired, and before which, all earthly glory disappeared. ** Religion,” says he, ‘‘ whether natural or revealed, has always the same beneficial influence on the mind. In youth, in health and prosperity it wakens feelings of gratitude and sublime love, and purifies at the same time that it exalts; but it is in misfortune, in sickness, in age, that its effects are most truly and beneficially felt ; when submission in faith, and hum- ble trust in the Divine will, from duties become pleasures, undecaying sour- ces of consolation ; then it creates powers which were believed to be ex- tinct, and gives a freshness to the mind, which was supposed to have pas- sed away for ever, but which is now renovated as an immortal hope ; then it is the Pharos greeting the wave-tossed mariner to his home, as the calm and beautiful still basins or fiords surrounded by tranquil groves and pas- * toral meadows, to the Norwegian pilot escaping from a heavy storm, in the North sea, or as the green and dewy spot gushing with fountains to the ex- hausted and thirsty traveller in the midst of the desert. Its influence out- lives all earthly enjoyments, and becomes stronger as the organs decay and the frame dissolves ; it appears as that evening star of light in the horizon of life, which we are sure is to become in another season a morning star, and it throws its radiance through the gloom and shadow of death.” We would strongly recommend this volume, not only to the study of scientific men in general, but especially to those who are just entering upon - their philosophical career. At that dangerous period when presumption and scepticism are the attendants of knowledge, it will not be an unprofi- table lesson to read in the lives of Newton and of Davy, that in minds of the highest order, humility and piety are the genuine offspring of true science. ‘ 186 Scientific Intelligence, Agt. XX.—SCIENTIFIC INTELLIGENCE. I. NATURAL PHILOSOPHY. ELECTRICITY. 1, Power of metallic rods or wires to decompose water after their con~ nection with the galvanic pile is broken.—In the experiments which I un- dertook in 1806-7, in company with Mr Hisinger, we had found that rods of metal which were employed to decompose water by means of the gal- vanic pile continued to develope gas after their connection with the pile had ceased,—a circumstance which seemed to indicate a continuance of elec- trical state, though these rods showed no action upon any other portion of liquid, even of the same kind, than that in which they had been placed during their contact with the pile. This observation, which I had almost forgotten, has been lately confirmed by Pfaff, who has also added to it se- veral others of a similar kind. We might suppose such effects to be pro- duced by a residual polarity, both in the liquid and the metal, showing itself, as long asit continued, by a continuance of chemical action ; but some of Pfaff’s experiments seem to oppose this idea, for he found that the ad- dition of ammonia to the liquid; by which all its internal polarity was de- stroyed, did not deprive the wires of their effect. The metals which ac- quire this property in the highest degree are zinc and iron, next to which is gold. He attempts to explain the phenomenon by supposing that the continued passage of the electrical stream had brought the elements of the water nearer to a state of separation, so that a very slight influence was sufficient to destroy their union. It must be confessed, howeyer, that we cannot at present advance a satisfactory explanation.—Berzelius, Arsberdt- telse, 1829, p. 33. 2. Detection of alloy in silver by the magnetic needle,—Oersted has made an ingenious and novel application of the magnetic multiplier. — He finds that if a good electro-magnetic multiplier with double needles be suspended by a hair or a thread of unspun silk between two pieces of wrought silver, differing only one per cent. in the quantity of copper they contain, so sensible an effect is produced upon the needle as to render this a more accurate method of proof than the common touch-stones. Small trigl plates are made of different degrees of purity, and the piece to be tried is compared with them in the following way: A thin piece of woollen cloth is dipped in muriatic acid, and laid upon the trial plate, after which the piece to be tried is brought into contact with the acid and the wire of the multiplier. The deviation of the needle shows which contains the most alloy, and another trial plate must be employed till the needle cease to be affected, when both are of equal fineness. In coming to a conclusion on this point, howewer, several circumstances are to be taken into conside- ration. Wrought silyer goods are generally deprived of a portion of their copper by the action of acids, so as to render the surface finer than the inner part of the metal ; the proof plates, therefore, must be prepared in the same way. Another source of error in the indications of the needle are the unequal polish and size of the two pieces of metal; the latter of Chemistry. — 187 these is especially difficult to overcome when the surface of the metal to be proved is not plain, - When, instead of muriatic acid, a dilute solution of caustic potash is employed, and the result is unlike, it is shown that copper is not the only alloy, but that brass is present ; and the potash so- lution renders that which contains brass so positive, that it seems conside- rably purer than the trial plate. This is the case also in a very high de- gree when the alloyed metal contains arsenic, for example when what is called white metal has been used for an alloy. This mode of proof is exceedingly interesting in a scientific point of view, and cases may occur in which it can be employed with advantage ; but the sources of error can scarcely be ever so completely done away with as to make it a practical instrument in the hands of the silversmith, as Oersted seems to expect,— ‘Berzelius, Arsberiittelse, 1829, p. 123. II. CHEMISTRY, 3. Double Metallic Chlorides.—Bonsdorf, in a paper referred to, page 146 of the present number, has described a number of double chlorides of mereury, gold, platinum, and palladium. The following formule represent the composition of some of the double chlorides of mercury and platinum. Those of mercury were formed by digesting a cold saturated solution of the salt on the corrosive sublimate in powder. | K Cl + 4 Hg Cl + 4 ag. Chlorides of mereury and potassium fx Cl + 2 Hg Cl + 2 a9. KCl+ Hg Ci + 1 ag. - ‘The last of these forms large right rhombic prisms. Chloride of mercury and sodium — N Cl+2Hg Cl + 4aq. barium Ba Cl + 2Hg Cl + 2 ay. : _ f§Ca Cl + 5 Hg Cl + 8 ag. eolefam | 86 FG) Cl + 2Hg Cl + 6 ay : Mg Cl+3Hg Cl + ag. aera ts Mg Ci + He Cl + 6 ag. Manganese = MnCl+ Hg Cl + 4ag. Tron = Fe Cl+ Hg Cl + 4ag. In these salts Bonsdorf considers the corrosive sublimate to act the part of an acid which he calls Acidum Chloro Hydrargyricum. Chloride of Pla- tinum and barium = Ba Cl + Pt Cl? + 4 a9. strontium = Sr Cli+ PeCl?2 + ag. calcium Ca Cl + Pt Cl? + 8 ag. ' — JSMg Ci + Pi Cl? + 6 ag. SSF, Mg Cl + Pt Cl? + 2 ag. a yellow powder manganese = Mn Cl + Pt Cl? + 6 ag. The double salts of platinum with iron, zinc, cadmium, cobalt, nickel, and copper, are isomorphous and identical in composition with that of manganese containing all six atoms water. A great number of other double chlorides of mercury and palladium with the chlorides of the more positive metals were formed, but none of them analyzed. 188 Scientific Intelligence. 4. Freezing point of Alcohol.—In some ‘gbservations on this subject ina letter to the editor of the Annalen de Physik, xvii. p. 162, Prof. Munckle of Heidelberg, states the following facts : 1. Very good cogniac froze at Melville island at a natural temperature, according to Parry, of 48°.5 cent. 2. Alcohol of 801 specific gravity at 20° c. at its point of greatest den- sity according to my first experiments at —56°.6 cent., and its probable freezing point is 58° cent. 3. Alcohol nearly absolute of specific gravity 798 froze, according to Hutton, at 79 cent. 4. Absolute alcohol of specific gravity 791 has its point of greatest den- sity, according to my second experiments, at —89.4 cent, and its probable freezing point at 92° cent. III. NATURAL HISTORY. ” MINERALOGY. 5. Iron Pyritesx—It is known to mineralogists that common or octo- haedral pyrites and the white pyrites, which from their difference of form were considered by Haiiy as different species, were found by Berzelius tobe identical in composition, or at least that no such difference existed as to warrant their being considered as different species. The explanation then given by Berzelius has been confirmed by later experiments, and he has pub- lished the following additional remarks: ‘* When a portion of common pyrites was permitted to fall asunder, I found it to be caused by the forma- tion of a small quantity of protosulphate of iron, which burst asunder the crystallized mass. When the,salt was dissolved in water no trace of free sul- phur was obtained, from which it appeared, that the efflorescing pyrites con- tains particles of F eS (sulphuret of iron,) which, changing to the state of salt, tears asunder the rest which undergoes no change. When the small quantity thus changed into sulphate of iron is compared with that which remains unaltered, I did not think that the results of analysis could be ob- tained to such a degree of accuracy as to determine the matter with cer- tainty. I have since obtained a satisfactory proof of the accuracy of this explanation. I heated carbonate of iron gently in a stream of sulphuret- ted-hydrogen. There were formed first sulphuret, and afterwards bisul- phuret of iron. The experiment being stopped before all the iron was changed into bisulphuret a pyrite was obtained, which in a few days fell asunder in all directions, and. changed into a woolly mass of vitriol of ten times its former volume. Sesqui-sulphuret of iron prepared from the oxide has not this property. It seems, therefore, highly probable, that the falling asunder of the common pyrites arises from the electro -chemical action of the electro-negative bisulphuret upon the sulphuret which is here and there mixed with it in small particles.—Berzel. Arsberdt. 1829, p. 129. Kohler finds the specific gravity of common pyrites to vary from 4.826 to 4.837 ; of the octohaedral from 4.8446 to 4.9074 ; and that of the cubi- cal to be 4.9188.—Poggend. An. xiv. 91. Celestial sere July—October sited 189 ArT. XXL —CELESTIAL PHENOMENA, From July 1st, to October 1st, 1830. Adapted to the Meridiun of Green- wich, Apparent Time, excepting the Eclipses of' Jupiter's Satellites, which are given in Mean Time. N. B.—The day begins at noon, and the conjunctions of the Moon and Stars are given in Right Ascension. JULY. DD He. M. S. D. He M. &. 19 6 4. § 4 0 0 08 4¢€8 23 5 7 enters 5 0 16. © 25. 5 40 56) dr Q ) 39'N. 5 14 24. Full Moon. 26 2 3 © j) First Quarter. 8 11 38 5m. I. Sat. 2 28 8 5 4m 9 © Greatest Elong. 30. 8 52 47 Em. III. Sat. 2/ 9 17 52 30) dace) 30N. 12 15 36 Last Quarter. SEPTEMBER. 13° 11 Sd» 1 8 30 54 Em. I. Sat. 2/ 15 13 32 58 Em. I. Sat. 2 Moon eclipsed, visible 15 16 45 7T)d7B)4i'N 2 8 50 Begins. 15 23 21 4+) da & ) 22’N. 2 9 48 Total darkness begins. 19 12 14 New Moon. 2 10 37 Kcliptic 2 22.7 SES 2 10 38 Middle. 22 37 fd? 2 11 28 End of total darkness. 22 22 38 enters a 2.12 26 Eclipse ends. 24 9 S56 45 Em. I. Sat. 21° 40’ digits eclipsed -25. 9 23 Imm. II. Sat. 27/ from the N. side of 25 12 48 37 Em. III. Sat. 2/ the earth’s shadow. 27.8 36 First Quarter. 4 Y Stationary. 29 14 d« I 5 10 0 5)d% H ) 6WN. 31 11 51 54 Em. I. Sat. 2/ : a 34. 50 ye III. Sat. 31 19 2 43 #14 #& Ceti /) G4’/N. HgO 9 1 58 (Last ve dn AUGUST. 9 9 9 24 Em. TV, Sat. 2/ 1 ll. 36 17 Em. I. Sat. 7 12 18 Sdh 4 0 57 Full Moon. 14 9 doe 4 8 30 Sup. 6 16 14 28 New Moon, ©) 6 10 10 lly dose) 40'N. Ecl. Invis. 8 18 dh 17 Pw Elong. 10 20 8 Last Quarter. 18 12 ll 22 25 22) d78)33'N./] 19 3 15 1l 23 52 aS ae | See 14 15 h6d® 23 «1 «(OI : 66 5h an 15 10 SdeN 24 8°46 13 Km. I. Sat. 7/ 16 10 11 11 Em. 1. Sat. 24 18 52 ) First pani 17 Ecl. Invisible. 27 8 22.26 Em. II. Sat. 2/ 17 23 53 © New Moon. 29 1 aQ 18 ¢ Stationary. 30 21 © Stationary. Times of the Planets passing the Meridian. JULY. Mercury. Venus. Mars. Jupiter. Saturn. Georgian. meii he sfhhivoleuy ‘ bya fi’ hicn h./ hy 122 1538 Sh WG 16 43 12. 16 2 36 14 13 22 35 21 19 16 14 ll 2) 1 53 13 9 25 23 17 21 25 15 42. 10 27 1 10 12 IL AUGUST. | 1°23 “SF «21-23 15 22 9 56 0 47 #11 58 13. 0.36.) 2b. 49 14 43 9 6 O21 Fs AES 68 6 bw § 22 «6 13 58 8 19 23 25 10 7 190 Mr Marshall's Meteorological Observations SEPTEMBER. | Dp h ” b iif Bo Rayke4 ee Mi. ¥ 1 hr 922 15. 33 29 7. 53.23, 3 9 57 13° 1° 32) 22 "SO 12° 35 110 m2 ee 25 1 27 2 43 lh 38 6 30 21 48 8 30 Declination of the Planets JULY. Mercury. Venus. Mars. Jupiter. Saturn. Georgiatt. Slag 94.58 , ° , e ¥ ° I 19 IN. 17 28N. 7598S, 22548. 27 ON. 18 308. - 13 2138 2016 6 19 23 4 16 35 \ ie gees 25 2235 21 57 5 6 2313 «216 8 18 44 AUGUST. 1 2033 22 18 4 37 23 17 15 22 18 49 13 13 20 21 46 418 23 23 15 24 18 56 25 4 27 19 45 4 35 23 26 14 55 18 2 SEPTEMBER. 1 0 378. 17 56 4 59 23 27 14 38 19 6 13 8 19 13 53 5 53 23 28 14 7 19 12 25 13 29 8 53 6 39 23 26 13 42 19 16 7 ail — in in Pe Art. XXIL—Summary of Meteorological Observations made at Kendal in March, April, and May 1830. By Mr Samu Marsuatt. Com- muhicated by the Author. State of the Barometer, Thermometer, &c. in Kendal for March 1830. Barometer. Inches. Maxithum on the 27th, - - ° 30.38 Minimum on the 15th, - F « 29.02 Mean height, © - 4 - ey. 29.82 Thermometer. Th Maximum on the 29th, - - é 58° Minimum on the 8th, . - 26.5° Mean height, - - - 43.17° Quantity of rain, 5.045 inches. Number of rainy days, 15. Prevalent winds, south-west. The frost, which in the two preceding months had been so severe, has scarcely been experienced in this month. The weather during the great- er part of the month, and particularly the latter, has been remarkably mild and genial, and the thermometer has seldom been so low as the freezing point. The equinoctial gales prevailed about the middle of the month with great violence, and were attended with sudden gusts, which are among their distinguishing characteristics. The barometer has mostly been high, but frequently affected by the winds. From the 9th to the 24th the weather was mostly wet and dull. No snow of any consequence has fallen since the 15th, on which day we had frequent hail atid snow showers. made at Kendal in March, April, and May 1830. 191 April. Barometer. Inches. Maximum on the 27th, : : : 30.00 Minimum on the 24th, “ Sa ; 28.75 Mean height, - . : : 29.50 Thermometer. Maximum on the 30th, < - “ 69° Minimum on the 4th, - - = - 23° * Mean height, — - : . : é 46.30° Quantity of rain, 5.656 inches. Number of rainy days; 21. Prevalent wind, west. This has been an exceedingly wet month,—at least on many days the showers have been long in continuance, though the quantity when mea- sured has not proved great. We had rain every day, except one, from the 7th to the 27th. At the early part of the month the nights were frosty, but the thermometer has not been so low as the freezing point since the 5th, so that the season has been very favourable in promoting vegetation. It is remarkable that we have not been visited this year by the N. E. and E. winds, which almost uniformly prevail in this and the next month. It is attributed to the unusual mildness of the winter in the northern countries of Europe. May. Barometer. Inches. Maximum on the 16th, - = 30.04 Minimum on the 26th, - . - 29.08 Mean height, . - : - 29.69 Thermometer. Maximum on the Ist, é P 3 73° Minimum on the 4th and 14th - - j 36.5° Mean height, - , 51.97° Quantity of rain, 2.831 inches. Number of rainy days, 14. Prevalent wind, west. Though there has been for the most part of the month ungenial weather, arising either from dry easterly winds or showers, yet, from the mean of the thermometer, it does not appear that the air has been so cold as our feelings alone would have led us to conclude. The barometer has been mostly low, and the dry winds which generally visit us much earlier in the season, prevailed for the most part in the E. and N. E. from the 7th to the 14th, and during the day-time occasionally afterwards, and yet the wind has been more in the west than in any other quarter through the month. The quantity of rain for the month is less than might have been expected, but the rain generally fell in drizzling showets, though they were frequent. We have had no frost during the month, but the dry winds about the middle retarded vegetation, though in a less degree than they usually do. | * N. B. 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Art. I.— Scientific Men and Institutions in Copenhagen. By James F. W.Jounston, M.A. Communicated by the Author. I enreren the capital of Denmark on Saturday the 11th of July 1829, and on the Monday following paid an early visit to the University of Copenhagen. The buildings lie detached and scattered about in several adjoining streets in the north-west part of the city. They produce, therefore, no combined effect,— present no hallowed courts of which history can tell that here lived, and taught, and studied the learned men of ancient days, and whose forms the student’s fancy can still. realize silently flitting through the old archways, or loitering in deep medita-_ tion along the secluded cloisters. ‘They have nothing in their exterior, taken thus singly, to awaken any of those undefined, yet peculiar feelings with which we pace the halls and courts of those seats of grave and venerable learning founded by the li- -berality of our forefathers in our own rich land. Even though united, they would hardly appear imposing, for they are plain brick buildings, void of ornament, and of all attempts at archi- tectural display. A portion of them, the Studit gaard, the very core of the university, the seat of the consistory, is almost en- tirely in ruins, having been burned along with the Fru Kirke, and several adjacent buildings during the bombardment in 1807, and never since repaired. The church, which is the largest in the city, has been only recently re-opened, want of money caus- ing the erection of public buildings in Copenhagen to go on very slowly. It were to be wished that the spire of this church, thrown down at the same time, were again raised to its proper NEW SERIES, VOL. ILI. NO. II. ocroBER 1830. N 194 Mr Johnston on the Scientific Men elevation, and the university buildings repaired, as in their pre- sent state they serve only to awaken recollections and revive feelings which had much better be forgotten. The University of Copenhagen was founded by King Christ- ian the Ist, with the permission of the Pope, in the year 1478, and the ordinance by which it was established in its present state is dated May 1788. . The number of professors at present is 36, divided into the four usual faculties. Of these three ordinary and two extraordinary belong to the theological, four ordinary and one extraordinary to the law faculty, four or- dinary to the faculty of medicine, and nine ordinary and twelve extraordinary to that of philosophy. There is also one lectur- er on philology, one upon geology, and two privatim teachers of anatomy and animal physiology.* ow The ordinary professors have higher rank and emoluments, and are members of the consistory. ‘The term extraordinary implies little more than supernumerary. When a man studies with a view to a professorship, he proceeds something after the following manner. He prepares himself, passes the required ex- aminations, &c. and receives the successive degrees of master and doctor in the faculty to which he attaches himself. He is then in a state to give lectures in that faculty, and is therefore called Doctor Legens. After obtaining the required permis- sion, he announces his course in the printed, catalogues or Index _ Lectionum, and lectures a year or two for nothing, being a pri- vatim docens, or private teacher. If he display sufficient talent, — he is then probably appointed a lector (lecturer) by Govern- ment, with a small salary of perhaps 400 dollars (L. 40.) In course of time a vacancy happens, and he succeeds to a chair, becoming professor extraordinarius, with a salary of about 600 dollars. By-and-bye he succeeds to a seat in the consistori- um, and he is then a professor ordinarius, with from 1200 to 1600 dollars, which is the highest. These salaries are derived from various sources, partly from lands, partly from the royal and church tithes, from ‘ground-rents in Copenhagen, from the interest of money, and from the study money (studii. skatten) paid after a certain rate’ by all the churches and clergy in the kingdom. Formerly particular lands and other sources of re- venue were attached to each chair, and the professors managed * This list is taken from the Index Lectionum for May 1829. The number of professors appointed by the foundation is something less. and Institutions in Copenhagen. 195 them independently, as they thought most for their own benefit. Such a living was called a corpus, but in 1796 the corpora were incorporated into a common fund, from which are now paid all the salaries and other expences of the university. In return each professor is ‘* bound to hold public prelec- tions pro officio without payment, over an important part of his science ;” and the regulations say further, that ‘* the lectiones publice shall be given only upon that part of the science which is most necessary for all the students, the other and more eru- dite parts being treated of in the private and most private (pri- vatissimis) courses.” Yet this would seem not to be so strictly enjoined as to be incapable of invasion, for in the Index Lec- tionum, dated May 1829, I find Professor Oersted announcing his public lectures for the first T'wesday of every month—*“< on the recent discoveries in Experimental Physics,”—and his pri- vate every-day—on “ Experimental Physics,”*—and Professor Zeise, his publie twice a-week—* on the Elements of the Doc- trine of Imponderable Bodies,”—and his private three times a+ week—* on Chemistry in general,”—to which latter it is added, that they are particularly accommodated to students of medi- cine and pharmacy, and will be illustrated by experiments. + For these private lectures they are allowed to take fees, but the trifle obtained can scarcely be an object to more than one or two individuals ‘who have large classes. The honararium is, ’ Jimited to four, or where there are experiments to five dollars each course, but all are admitted for nothing who bring a “ tes- timonium paupertatis,” as the sons of the clergy generally do. Thus, even those who are rich never pay more than ten dollars a year, or about a pound Sterling. Professor Oersted, whose — class amounts to 200, obtains most in this way, and yet his in-- . come from fees does not exceed 400 or 500 dollars. * Dr Joh. Chr. Oersted, Phys. Prof. Publ. Ord. lectionibus publicis primo die Martis cujusque mensis horis 6-8 habendis, inventa recentissima ad Physicam experimentalem spectantia exponere perget ; lectionibus privatis hora matutina 8-9 physicam experimentalem docebit ; nec iis deerit, qui unam alteramve partem physice uberius sibi explicatam desideraverint. + Dr Will. Christophorus Zeise Chemie Prof. P. E. publice diebus Mercurii et Saturni hora 12—elementa doctrine de Imponderabilibus Che= micorum exponet ; privatim diebus Lune, Martis et Veneris eadem hora Chemiam generalem lectionibus, Medicine et Pharmacie Studiosis impri- mis accommodatis, delineabit experimentisque, illustrabit: qua tradita fuerint examinando subinde repetet. 196 Mr Johnston on the Scientific Men The distribution of subjects for lecture among the different members of the same faculty is not fixed by the statutes of the university. In that of philosophy, where the field is so exten- sive as to call for some limitation, they are more tied down to certain professions, but the number of professors enables them to choose the department most congenial to their taste. In the other faculties, it is simply provided, as in many of the German universities, that lectures shall be given on certain subjects, and that ‘ the professors shall so arrange their prelections that each department shall be treated of during every Cursus Aca- demicus,”—** and that no collegiams 9 or course of lectures shall be extended beyond a year.” | 7 | Previous to the year 1788 there was only one session and one course of lectures by each professor annually, commencing nearly as in the Scotch universities, at the latter end of the year, and continuing till the middle of summer, but the statute then published announces, that ‘“* whereas such a cursus acade- micus had caused much loss of time, the academical year shall hereafter be divided into two courses, namely, from the first of May to the beginning of October, and from the first of Novem- ber to the beginning of April.” ‘The only holidays at present are, in summer, Whitsunday week, the last week in J uly, and the first week of August,—and in winter, fourteen days, from the 24th of December to the 6th of January. Lectures are read on every day of the week during the cursus; and the two recesses, of a month each, are much taken up by the various examinations appointed for those terms. Thus, the professors have very little time at their own disposal, but the king is al- ways willing, due cause being shown, to grant a dispensation from active duties even for entire sessions. The Polytechnic Institution of Copenhagen, inaugurated i in November last, is one of those many institutions to which the rapid advance and diffusion of natural science has given birth. Tt is confined, as its name implies, to the practical and experi- mental sciences; and is intended to give a higher and more useful education to those not intended for the learned profes- sions than is to be had in the ordinary schools. The instruc- tions given extend to the higher Algebra, Analytical Geometry, the Differential and Integral Calculus, Pure Mechanics, the. science of Machinery, the Mechanical and Chemical part of and Institutions in Copenhagen. 197 Physics, Optics, Agriculture, Chemistry, general, analytical, and as applied to the arts, Technology,Crystallography, Oryc- tognosy and Geognosy, Botany and Zoology. ‘To teach these sciences ‘seven professors are already appointed, two of whom are chemical, and for practical purposes there are two labora- tories, to which all students are admitted under certain regula- tions, and a work-shop in which, under proper superinténdence, practical mechanics is taught. The students are of two classes, partial, those who attend perhaps one or two courses of lectures, and regular, who attend all the classes, and go through the regular course assigned by the statutes. ‘The former are admitted without any examina-— tion at the rate of four dollars, (8s. 6d English,) a year for each course, and 6s. for the laboratory or work-shop, and thus the po- pular sciences are open to all at a very moderate charge. The regular students undergo a previous examination in their native tongue,—in French and German, History, Geography, Arith- metic, Geometry, Trigonometry, Algebra as far as Quadratic Equations, and the theory and uses of Logarithms. ‘They pay ten dollars quarterly, or a little More than four guineas a year, for all the benefits of the institution. None of these fees are paid to the professors,—all go to a common fund, from which the total expences are paid, with such aid from government as may be found necessary. The entire Cwrsus occupies two years of two sessions each; after which the regular students undergo the | Polytechnic examination. This examination, at the choice of the student, may extend either to the mechanical part, compris- ‘ing Mathematics and the knowledge of Machinery, Machine Drawing, Mechanics, Chemistry applied to the Arts, and Tech- nology, in which case he becomes, after examination, a Can- didate in Mechanics, or it may comprise a certain portion of these with all the other branches taught in the institution, in which case he becomes a Candidate in applied Natural Science, or he may be examined in all these together, when he has the title in both, (Candidater i Mechaniken og anvendt Naturvi- denskab,) and receives his diploma accordingly. The state of natural science in Copenhagen is not very high, though the University reckons several celebrated men among its scientific professors. Chemistry, botany and zoology, are the favourite studies. Even these, however, can boast of com- 3 198 Mr Johnston on the Scientific Men paratively few cultivators. Here, ag in most countries, the greater number, indeed the great body of the students, confine themselves exclusively to what is necessary for passing their examinations, and the knowledge this requires, they may attain either by attending the prelections, or by private study. _ There are few who cultivate science for its own sake, few amateurs, those who do give themselves up to it having generally a view to the professions. Among a population of less than two mil- lions, by no means rich, many independent cultivators of science are hardly to be looked for, and yet, even here, they contrive always to have a very respectable amount of talent and indus- trious perseverance collected together in the professional body. There is little inducement to study for a chair, and hence a predilection to science may be looked for in those who choose to do so. It may often be remarked of the men of science in England and the north of Europe, that the former are general- ly more active before they obtain chairs or other lucrative em- ployment, the latter after. The former often work to obtain emolument, the latter, having obtained the means, begin to la- bour for distinction. I wouldtot be understood by this remark to make any thing like a sweeping assertion against our scienti- fic men, either those who fill public functions or occupy private stations. No country in Europe probably can produce so many examples of private devotion to science as our own: and it is the boast of our public seminaries, that among their professors are ranked some of the first men in Europe in every department. But they who have attended to the history of scientific men in Great Britain will recollect many instances of individuals en- dowed with rare talents for the promotion of science, who, after making a few successful steps in advancing her interests or en- larging her boundaries, have neglected, or utterly forsaken this noble pursuit, for one that promised a more solid and immediate, and, probably, a more golden harvest. Professor Oersted, the founder of the science of electro-mag- netism, stands at the head of the physical school at Copenhagen. He is a man of 52 years of age, below the middle size, of open and florid complexion, inclining a little to corpulency, and of kind and gentlemanly manners. In conversation he has a habit of looking rather upwards, acquired probably from the peculia- rity of his vision, being very near-sighted. He is universally and Institutions in Copenhagen. 199 esteemed, riot for his talents only, and zeal in the cause of science, which have procured him high respect in foreign coun- tries, but also for his pleasing and amiable disposition. Asa writer he was formerly known chiefly for his theoretical and me- taphysical papers. Many of the views he then entertained he is said to have abandoned since he began to “ interrogate na- ture for himself.” His first experiments on electro-magnetism, when he discovered the action of the galvanic pile on the mag- net, were made so late as the winter of 1818-19, and the most complete view of the results then obtained is contained in a short Latin dissertation * of four quarto pages, dated Copenha- gen, July 1820.+ When I called on him I found him engaged with his galva- nic apparatus on a series of experiments which he proceeded to explain to me without the slightest reserve. ‘There is nothing more gratifying, and few things more useful to a lover of the experimental sciences, than to see the apparatus and witness the manipulations of successful cultivators in their several labo- ratories. There are so many minutiz in the forms of apparatus —in the mechanical contrivances for rendering them efficient, or for saving time; and in the modes of manipulation which expe- rience suggests, but which no one would ever think of putting into. a book,—that it is now almost necessary for the cultivator . of experimental philosophy, who would improve his time, to make himself acquainted with these various matters by direct and per- sonal observation. I paid Oersted several visits ; saw all his ap- paratus, which is entirely modern and in excellent order; and found him on every succeeding visit the more pressing upon me to return. ‘The establishment of the Polytechnic Institution had devolved upon him, and then occupied much of his time ; but when not engaged with this affair, I found him always busy either writing or experimenting. He is publishing at present a « System of Mechanical Philosophy ;” and on showing me some of the proof sheets, he observed, ‘ I am taking a long time to complete it—I get on so slowly, for when I am writing, a new idea comes into my head, and away I go to my experiments.” His motives to exertion may be judged of from his remarks, when speaking of a celebrated lecturer on chemistry in Scot- * Experimentu Circa effectum Conflictus Electrici in Acum Magneticam. + Professor Oersted has given the fullest account of his discoveries in the Article THERMo-ELECcTRICcITY, which he has written in the Edinburgh Encyclopadia.—Ep. 200 Mr Johnston on the Scientific Men land. ‘* He has every thing in fine order. When I was in Scot- land he did me the honour of showing me all his apparatus; but he might do more than give his lectures well.”—‘* Ah but then he makes money, and perhaps thinks that enough.” —“ Yes, but when a man dies, where is his money !”—‘ I make honour,” he said to me on another occasion, “I make honour my first reward ! Money may come after if it will.” He is rather a con- cise writer, and prides himself a little on this quality of his com- positions. ‘I write,” said he to me one day, “ as if I were to pay for every line. I know some men who write as if every line were to be paid for.”—‘* I had once a memoir sent to me, — which, among many good things, contained also many indiffe- rent.” My remark to the author was, “ If you will leave out ten dollars worth, it will be worth 100 dollars more !” He proposes to publish a volume of memoirs, comparing with each other the results of metaphysical and experimental philo- sophy, as soon as his work upon mechanics is fairly out of his hands. Like most other discoverers, he complains of plagia- risms and unjust appropriations by others of what he was the first to make known; but such things to a certain extent:can hardly be avoided without an access to foreign publications which naturalists cannot always command, or their knowledge of lan- guages enable them to make use of. Oersted is secretary to the Academy of Sciences of Copen- , hagen, and his merits have procured for him the order of Dane- | broge, and the title of counsellor of state. The Royal Society of Copenhagen—‘ Det Kongelige dan- ske Videnskabers Selskab”—is the oldest, as it is the most im- portant Philosophical Society in Denmark. It was founded in 1743. There is also a Society for the Encouragement of Ex- perimental Science, but it is of a practical kind, partaking of the character of the ‘‘ Society for the Diffusion of Useful Knowledge” in this country. ‘The Royal Society has had the direction of two highly important works, a Complete Survey and Geography of Denmark and the Dukedoms, and a Dictionary or Ordbog of the Danish language. Oersted, as I have already mentioned, is secretary and editor of theit yearly Transactions. Zeise is well known to chemists as the discoverer of Xantho- gen and its compounds. He is professor of chemistry (professor extraordinarius) in the university, and has lately been appointed ordinary professor in the Polytechnic Institution. He isa la- and Institutions in Copenhagen. 201 borious man, but of a melancholy and reserved habit, and shuns rather than courts society. ‘Though he paid me-some little at- tention, I found him, on that account, but an indifferent com- panion for a stranger, to whom the most communicative person is generally the most acceptable. In his laboratory, which I saw nearly in its perfect state in the new buildings of the Poly- technic Institution, on my second visit to Copenhagen, there was nothing which struck me as worthy of remark. _ It consist- ed of several apartments, but all of them seemed to me too small and confined. He is engaged at present with a work on the Elements of Chemistry, the first two volumes of which are already published. ‘The last system of chemistry in the Da- nish language is thirty years old! In the university, therefore, they use French and German works, which the students can all read with ease. In the Polytechnic school it is one of the re- gulations, that all the lectures shall be after some printed book, either Danish, French, or German, and hence an inducement to write Danish books, as it in some measure insures their sale. Though chemistry be one of the more popular sciences in Denmark, as it is elsewhere, yet it is but little studied. This may arise partly from the want of a proper lecturer on that de- partment in Copenhagen. Zeise indeed told me he had once or twice given a public course unconnected with the university; _ but I could not learn that he had been very successful. He has ample science, but will hardly, I should think, make his lec- tures showy and attractive. In so large a city, a good experi- menter, with a popular manner, might surely secure a respectable audience for such an annual course of lectures. Even students of medicine give little attention to it, as the knowledge of che- mistry required for degrees in that faculty has not hitherto been very extensive. Zeise’s class consists generally of about forty ; but as it is a course of chemical pharmacy, it is attended chiefly by those who are educated as apothecaries. The most diligent and best known chemist in the Danish do- minions is Pfaff, of whose labours the German journals show ample proofs. He is besides the author of some chemical and pharmaceutical works of considerable repute; but as Kiel is a German University, and the prelections are delivered in Ger- man, his books are also in that language, and therefore not fit- ted for the islands and states of Denmark proper, for which 202 Mr Johnston on the Scientific Men Zeise’s work is intended. I wished much to have visited Pfaff and the University of Kiel, but the rapid approach of winter - on my return to Copenhagen in the end of October prevented me from prolonging my stay in the north of Germany. Dr Forckhammer is lecturer on geology and mineralogy in the University, and of mineral and inorganic chemistry and ana- lysis in the Polytechnic Institution. He is known for several chemical papers, but has been more lately employed in eluci- dating the geology of Denmark, with a view to a map of its for- mations. He has visited the Faroe Islands, and published some account of their geology in the T'ransactions of the Danish Academy of Sciences. In the same work for 1825, he has written upon the structure of a part of Zealand and the neigh- bouring islands; and more lately (1528) a paper on the Island of Sylt, being the first of a series on the geology of Denmark. Geology and mineralogy receive little attention in Denmark. There is not even a work on mineralogy in the language. I at- tended one of Forckhammer’s lectures on geology, and found he had only four pupils. In his winter course he has about ten. There is little inducement, indeed, to study these sciences in that country. The mineral species it produces amount only to about thirty, and the geological formations are still more limited. While Norway remained in possession of the Danes they had. a boundless field for both studies. Every mineralogist knows how rich that country is in minerals, and Von Buch has shown it to be no less rich in a geological peint of view. Still in the splendid collections to be found in Copenhagen, | there are abundant facilities for the study of mineralogy. ‘To the Museum of Natural History is attached a cabinet of mine- rals, (King’s cabinet) particularly rich in specimens from Green- land, Iceland, Norway, and the Faroe Isles. The silver mines of Kongsberg in Norway have sent to it some splendid masses of native silver. One of these is about six feet long, two feet broad, and eight inches thick. Pieces of the rock are attached to it, but nearly half of the whole is solid silver; and the value of it is said to be 10,000 dollars. Another entirely of pure sil- ver is about two feet long by one foot in breadth and thickness.* This cabinet contains many unexplored treasures; most of the new Greenland and Norwegian minerals having long lain there - * IT did not see these specimens, and copy from a description, which is probably exaggerated. and Institutions in Copenhagen. 208 unknown and neglected. ‘The same is said to be the case also ' with the collection of minerals belonging to the university. Both indeed are little better than a sealed book—even the pro- fessors know little about them ; but the persuasion is, that many new things might be detected in them by a careful examination. They have hitherto been under the direction of a professor of the old school; who knew but little of the present state of his science, and, as some are wicked enough to say, cared still less. By a late arrangement, however, he has been relieved from the charge, and it is hoped a year or two will see these cabinets brought into the order they deserve, It is to be regretted, in- deed, that minerals collected during years of toil and privation, by such men as Giesecké, should be lost to the world through _the incapacity of a professor of mineralogy, whether that inca- pacity be the result of age or of any other cause. * But the mineralogist will not entirely lose his time at Copen- hagen. Besides other private collections, among which must be mentioned that of Conferancerad Monrad, which I had not the pleasure of seeing, he will visit with much gratification the splendid cabinet of the heir-apparent, Prince Christian Frederick. It is under the immediate care and superintendence of Count Vargas Bedemar, and is in the very best order. ‘Che Prince -and the Count are equally zealous and indefatigable in procur- ing additions to it, and equally courteous in showing its trea- sures to the stranger. I spent a portion of two days in it, and I owe to both an acknowledgment of their kind attention. It is arranged according to the system of Haiiy, and contains about 10,000 specimens. Were it only displayed in a larger suite of apartments, there would remain nothing to be desired. The Prince has also formed a geological cabinet, and his collection of shells which, from their not interesting me, I did not visit, is said to be as fine and as well kept as his mineral cabinet. It is probable that practical chemistry and mineralogy will * 'Things would appear to have been better managed in 1808, when Von Buch described the mineral collections of Copenhagen. He praises Pro- fessor Wad for being the first to put the royal cabinet in any kind of order, —and feels much pride in numbering so deserving an individual among his brother Wernerians. But twenty-two years have done much for mine- ralogy, and have rendered necessary a much higher order of talent and in- formation to the seientific arrangement of the productions of the mineral kingdom. 204 Mr Johnston on the Scientific Men be brought into greater repute, in consequence of the regulations of the Polytechnic Institution. It is there provided that each of ~ the chemical professors shall admit the students into his labora- tory twice a-week for three hours in succession. For this . purpose they are separated into three divisions, one of which is admitted each day, so that every student has two lessons, or six hours of laboratory- work every week. ‘The fee for this tone course is six dollars, or 12s English. The zoological part of the Museum of Natural History is un- der the care of Professor Reinhardt, and is said to have many treasures. Only part of these, however, are yet in a fit state for public inspection. This part consists chiefly of birds and fishes, and is open to the public twice a-week in a house in the Storm Gaden. This museum is also rich in shells and insects. Professor Horneman is well known to botanists. He is an old grey-haired man, beneath the middle size, and said to be approaching his eightieth year ; yet he is very active and indus- trious. Professor Zeise was kind enough to accompany me to » the botanic garden, connected with which and with the lecture- room is the house in which Horneman resides. Attached to the garden also is a library well stored with botanical works. It occupies a large room over that in which the lectures are delivered. Here we found him with two assistants, all busy among heaps of dried plants. ‘lhe work at which he has long laboured is the well known Flora Danica. It was begun in ' 1756, during the reign of Frederick the 5th, by both of whose successors it has been liberally patronized and supported. ‘The first ten fasciculi were published by Oeder, who travelled much and laboured indefatigably for the benefit of the work. He was-succeeded in the editorship in 1771 by Miiller, who, being more devoted to zoology than botany, published only five fasci- culi, and these of inferior merit. From 1783, to the beginning of the present century, it was under the care of the celebrated Martin Wahl, author of the well known Lnumeratio Planta- rum, under whose auspices six large fasciculi were added to the former fifteen. In 1804 the work came into the hands of Pro-: - fessor Horneman, who has been equally assiduous. He has pub- lished twelve parts, forming four volumes, containing each 180 plates, and describing in all about 900 species of plants. When the work may be completed it is impossible to say. The Flora . and Institutions in Copenhagen. 205 of Denmark cemprises about 5000* species, of which, though the work has been seventy-four years in progress, and for the greater partof the time indefatigably edited, only 2200 are yet published, so that little more than two-fifths of tie labour has yet been performed. ‘ When do you expect to have it finished,” I said to Horneman one day. ‘‘ Ah Monsieur je ne le finirai jamais. Je ne peut pas vivre assez long temps pour cela.”——-“ But how “Inany tomes do you think it will occupy.”——“* Quinze peut-etre ; c’est une chose tres laborieuse de faire un tel ouvrage.” Among the botanists on the continent it is pleasing to hear those of our own country spoken of in such honourable terms. Among cryptogamists the first question asked of me was usually, *< E'st-ce-que vous connoissez Monsieur Greville.a Edinbourg ;” for this exceedingly accurate botanist stands deservedly at the head of his department. We spoke of Dr Hooker: ‘‘ Oui j’en connois bien, mais je ne Pai jamais vu ;” and he pointed out to me upon his shelves Hook- er’s Flora Scoticu, his Exotic Flora and Jungermannia ; and with these Dilwyn’s Conferve and Sir J. E. Smith’s works. Then, as we went along the garden, he was careful to point out to me a red Potentilla from Nepaul (Potentilla formosa) which he received first from Glasgow. ‘¢ Mons. Greville,” said Horneman, ** vous lavez vu, il est homme grand, n'est ce pas ?”»—‘* Yes, he is above the middle size.”—“* Ah, Je l’ai figure a moi-meme—un homme tres grand.” —** How so? Is it that you thought him a great botanist ?”>— ‘* Peut-etre,—il est grand botaniste sans doute, surtout dans les Cryptogamiques,—dans les Cryptogamiques il est 4 peu pres parfait.” And Dr Hooker, “‘ Je Pimagine d'etre petit.” —“ But he is a tall man,”—‘“* Ah le voila! comment on se trompe de ceux quils n’ayent jamais vu !”—‘* And how came you to sup- pose Dr Hooker a little man ?”»—*‘ Je ne sais pas.”—“ But he is an eminent botanist !”—* Ah oui, oui, il est un de vos meilleurs botanistes, mais il ne faut pas d’etre homme grand pour devenir - grand homme.”—‘‘ Still don’t you think the chances are in fa- vour of a little man, for the same amount of genius will be more concentrated when it has less space to be diffused over, and don’t you see that most clever men are little."-—* Oui, oui, cest une * 1600 Cotyledonous. 3200 Acotyledonous. 206 Mr Johnston on the Scientific Men, &c. in Copenhagen. bonne idee, et quel malheur ne seroiteil pas pour nous trois s'il etoit necessaire d’etre homme grand pour avoir du genie ?” Botany shares, with chemistry, the little attention paid to science in Copenhagen. It is indeed the favourite study in Den- mark. It is taught in some of the learned schools ; and besides those whose course of study requires them to attend lectures on botany there are also a few who study it as amateurs. I have seen in North Jutland a party of half-a-dozen proceeding along the road with their vasculums slung over their shoulders. But the value set upon it in general does not seem to be very great. *¢ At the lectures which are given gratis,” said Horneman, “ I have perhaps a hundred pupils,—mais quand il faut payer, ma foi! je nai qu’ un vingtaine.”—* And what is the fee ?”»——*¢ Cing dallar !” about 18s. English. , The lecture-room is large, but, as I saw it, dirty and desti- tute of accommodation,—a simple table and chair in the middle of the room, and a few forms for the pupils, being all it contained. There are about it none of those agremens which throw so pleasing an air around the botanical lecture-rooms in Edinburgh and Glasgow. 'There was also a want of neatness in the keeping of the garden ;— it is more a storehouse of plants than an agree- able exposition of the beauties of vegetable nature. Still it is‘a rich storehouse; and though rather confined, contains about 7000 species. Professor Horneman is himself indefatigable, and I never found him unemployed. If he could inspire his gar- deners with a little of his own zeal, the appearance of things would soon alter for the better. The garden is kept up at the expence of government; and, though the low state of the Danish exchequer forbids any lavish expenditure on this department, yet the want of neatness, one would: think, cannot be entirely the fault of the authorities. Though the winters are colder in Copenhagen than with us, the summers are much warmer. Grapes, apricots, and figs all ripen in the open air. The branches of the fig are disengaged from the wall during the winter, stretched out upon the ground and covered up. Dr Schouw is extraordinary professor of botany. He was educated for the law, but, turning his attention to botany, was first sent out on a tour at the expence of government, and afterwards, by the desire of Horneman, elected professor extraor- Mr Henwood’s Account of Steam-Engines in Cornwall. 207 dinarius. ‘The geography of plants is the department to which he has zealously attached himself. He is already favourably known by an excellent work on ancient climate, and he has an- nounced one on the climate of Italy. During both of my visits to Copenhagen he was absent in that country collecting materials. The mathematical sciences are not much cultivated at this uni- versity. Euclid is taught in all the learned schools to the extent of four books,—a work by Dr Ursin, professor of astronomy, being employed asa class-book; but it does not occupy any prominent place among the studies included in the Cursus Academicus. The professors, however, arelearned men. The celebrated Schumacher is professor of astronomy, though, from dislike to Copenhagen, he generally resides at Altona. Pro- fessor Schmidten also has published several analytical papers in the T'ransactions of the Royal Society of Denmark ; and the following annonce would imply, that the fault does not lie with him if the higher mathematics are less deeply studied. M. Henricus Gerner Schmidten, Math. P. P. E. quatuor per hebdomadem diebus, hora accuratius indicanda4 mechanicam pu- ram publice explicabit. Tis preeterea, qui unam alteramve analy- seos sublimioris partem illustratam voluerint consulere studebit. Portose tio, 19th August 1830. Art. I1.—WNotice of the performance of Steam-Engines in Cornwall for April, May, and June 1830. By W. J. Henwoop, F. G.S., Member of the Royal Geological So- ciety of Cornwall. Communicated by the Author. Reciprocating Kingines drawing Water. — o o a~ 26a Se 8 j88 F# 3.5 23583 , IN, iy — Bibs Soe Su.” oes 45° S32 se Mines. 3.6 88 ao: ase es 27-o8°S rs) = od Ses wee 8. DE = 5 ws mes = s.2 os Sale ss 23 88% 828 325 ss B3385 As Hts wan SES Ae BABSSH Stray Park, - 64 7,75 5,25 7, 4,4. 29,5 Huel Vor, - 63* 7,25 5,75 17,5 5,9 — 27.9 53: 9, 7,5 19,58 5,3 448 48° 1K 5, 8,09 5,7 28,3 Poladras Downs, 70 10, 75 10,1 7,2 59,5 Huel Reeth, oo 6 OGG IGS Saree 208 Mr Henwood’s Account of Steam-Engines in Cornwall. ee ae Mines. sega 4a Se ES &25 2 & 38.2 a= 282 §22 Ses Balnoon, S 30° 8, rT 9,2 Huel Towan, - 80 10, 8, 11,2 ? g0 10, 8 9 6 United Hills, - 58 8,25 6,5 8,6 Crinnis, a 56. 6,75 /6,75...:,9,1 Huel Unity, - 52 6,66 5,75 9,19 60 7,25 5,75 13,8 Poldice, * 90 10, 7, 10,54 60 9,5 6,25 12,8 Huel Damsel, - 42 17,5 5,75 Qi, ° 50 9, v F 10,1 Ting Tang, - 63 8, 6, 15,2 . 66 9, TF cvs eal Cardrew Downs, 66 8,75 7, 11,67 Huel Harmony, 70 9,25 7, 9,68 Huel Montague, 50 9, a; 11, Dolcoath, * 7G''2'"9; 1,5 11,87 Great Work, - 60 9, 7, 10,25 Huel Caroline, 30... 7; 6, 29,3 : 53,5 8,33 7, 7,67 St. Ives Consols, 36 7, 7% 16,3 Binner Downs, 70 10, 7,5 10,9 64 9,83 7,75 10, | 42 9, 7,5 14,53 ConsolidatedMines,90 10, 7,5 8,82 | 70 10, 7,5 10,92 65 9, 17,5 16,94 90 10, 7,5 8,83 90 10, 7,5 7,3 655. 9, BB 19,45 United Mines, 90 9, 8, 7,9 ; 30. = 9, 7,5 13,66 Huel Beauchamp, 36 17,75 6, 13,5 Huel Rose, - 60 9, 7, . 14,8 Pembroke, 80 9,75 25 11,34 50° «9, yh 11,58 East Crinnis, - 60 5,5 5,5 8,57 TELS. seh 9,4: East Huel Unity, 45 8,75 6,75 13,15 Huel Hope, - 60 9, 8, 19572 Huel Tolgus, 70 10, 7,5 8,47 No. of strokes per minute. oes e a ae és Go bo | -_ GS Or Or =F et CO Or Ee MEV ADH ES OP MAIUWOAH ~I 01 2 “ PRAM Vv wv Or 32 80 WOO AMNAAN ID WD SAPD EOP AN SS Cr & OW vv 6] OF OF.G9 CO OF 69 SP 00 BP -ox Or =F OOO weight lifted 1 foot high by the consumption of 1 bush. of coal. Millions of Jbs. heme, OSD od to 69,4 3 ; Dr Moll’s Electro-Magnetic Experiments. a “uM 3 B om oS 3 > : : = os 23 oe SF 8 Bees S88 ew OM VSS Sy, £3 Sea3csq Mines Sq °Ss Sse H=Seg @=3 ata? . 2°" <3 _ E eerk & -3 te RB. We « Es lS BE GAR Cf BESe3 & = ‘ ) ms Sao SE S85 822 8e5 £8 52362 Tresavean, - 60 9, 2 7,67 5, 23,2 Huel Falmouth, 58 8,75 6,5 4,99 4, 29,2 6 Huel Sperris, - 70 10, 7,5 7,05 6,3 Huel Prosper, - 53 7, 7, 4,28 6, Huel Leisure, - 36 9,25 6,75 14,5 5,6. 36,9 70 9,833 7,75 6,1 . 4,9 Marazion Mines, 60 9, &, 9,35 6.6 54, Huel Vor, a ee 3, 12, 163 20,7 QT by 2,5 12,5 17,5 23,8 16,5 5, 2,5 8,5 25,8 15,1 Average duty 44,3 millions of lbs. lifted one foot high by the consumption of each bushel (84 lbs.) of coal. Watt’s rotatory double engines, working machinery for bruis- ing tin ores. 3 Average duty of rotatory double engines, 19.87 millions. * Watt's double engines. All the other engines are Watt’s single. Art. ITI.—Electro-Magnetic Experiments. By Dr G. Mott, © F.R. S. E. M. A. S. Professor of Natural Philosophy in the University of Utrecht. Communicated by the Author. Iw the Transactions of the Society for the Encouragement of Arts, Manufactures, and Commerce, Mr Sturgeon of Wool- wich, has given a description of an elegant and curious appa- ratus, with which many striking electro-magnetic experiments may be performed. Among these, is a soft iron wire, bent in the form of a horse-shoe, wound round with copper wire. ‘The ends of this copper wire, being made to communicate with the opposite poles of a galvanic apparatus, the iron becomes a strong horse-shoe magnet, capable of supporting a heavy bar of iron. On lifting the connecting wire out of the cups, the force is immediately destroyed, and again restored on plunging the connecting wire of the battery again in the cups. This apparatus I saw in 1828 at Mr Watkins's, curator of philosophical apparatus to the London University ; and the NEW SERIES, VOL. III. NO. Il. OCTOBER 1830. re) ! 210 Dr Moll’s Electro-Magnetic Experiments. horse-shoe with which he performedythe experiment became capable all at once of supporting about nine pounds. -T immediately determined to try the effect of a larger gal- vanic apparatus on a bent iron cylindrical wire, and I obtained results which appear astonishing, and are, as far as the intensity, of magnetic force is ie altogether new. I have anx- iously looked since that time, into different scientific continen- tal and English journals, without finding any further attempt to extend and improve Mr Sturgeon’s or Adina experiment.» I procured from Mr Watkins a soft iron wire, bent in the. shape of a horse-shoe. The length of the horse-shoe was about 8} inches, and one inch in diameter. A copper spiral wire was twisted round this iron from right to left (sinistror- sum.) The diameter of this wire was about } inch, and it was twisted or coiled eighty-three times round the iron. The ends of this wire were made to plunge in cups filled with mer- cury, in which the connecting wires of the zinc and copper poles of a galvanic apparatus were likewise immersed. The weight of the horse-shoe, together with its surrounding spiral wire, was about five pounds.* A piece of soft iron, con- structed in the same form as the iron which connects the ends or poles of a horse-shoe, or armed magnet, weighed about 13 pound, or 630 grammes. The galvanic apparatus used consisted of one single copper trough, in which a zinc plate was immersed. ‘The acting surface of this zinc plate was about eleven English square feet. When the conducting fluid was poured into the trough, the horse-shoe immediately became a strong magnet, capable of supporting about twenty-five kilogrammes or fifty pounds. If weights are added with some caution, this ewtempore mag- net may be brought to support seventy-five pout or thirty- eight kilogrammes. The south pole of the horse-shoe magnet is on that side on which the copper spiral wire is dipped in the cup connected with the zinc plate ; the north pole, of course, is on the side communicating with the copper trough. u * The pounds mentioned here, are Dutch weight, of 16 ounces in the pound. ‘This is somewhat heavier than avoirdupois. Two pounds are a little less than one kilogramme. But if no great accuracy | is required, two pounds may be estimated equal to one kilogramme. Ya Dr Moll’s Electro-Magnetic Experiments. Q11 We call the north pole of a magnet that end of it which, in a magnetic needle, points to the north. The rapidity with which such a powerful magnet, deable of supporting seventy-five pounds, is produced, is truly asto- nishing. With equal celerity the magnetism is destroyed and the poles reversed, merely by shifting the connecting wires of the battery from one cup to another. The magnetism of this horse-shoe is not, however, instan- taneously destroyed, merely by taking the connecting wires out of the cups, and without shifting them from one cup to another. Instead of suspending from the magnet the maxi- mum of what it is able of supporting, if a lesser weight, twenty pounds or ten kilogrammes be attached to it, the magnet will not cease to support the weight, immediately after removing the wires from the cups, but continue to attract the weight for a longer or shorter time, according to the strength of the ‘magnet. The heavier the weight which remains thus_ sus- pended, the shorter will be the time after which it falls down. If the iron bar which so connects both poles of the magnet is supported by the hand, whilst the wires of the battery are removed from one cup to another, the velocity with which the poles are reversed may be actually felt by the duration of the impression of the weight on the hand. This duration is cer- tainly much less than one-tenth part of a second. If we compare the velocity with which the poles are chang- ed, only by transferring the wires from one cup to another, with the trouble and time required to change the poles of a common magnet, capable of supporting 76 pounds, it becomes rather difficult to bring the rule of Horace, Nil admirari, in actual practice. If the poles of the horse-shoe are con- nected, not by the heavy iron rod, or supporter, but by a slender steel needle, the poles may be reversed before the needle by its weight overcomes the resistance of the air. When the wires are shifted, a transient motion is porns in the needle, but it does not fall. When the horse-shoe is loaded till the weight falls, its mag- netic force will be found considerably weaker, and some time must elapse before it becomes again capable of carrying the same weight as before. It is well known that common horse- 212 Dr Moll’s Electro-Magnetic Experiments. shoe magnets, when allowed to drop their load, are conside- rably weakened, and often never recover their former strength. In the experiments which I am now relating, the strongest action of the horse-shoe takes place the instant when the trough is filled and the connection is made. ‘Although this horse-shoe is only possessed of a transient magnetic force, the duration of which is limited to that of the galvanic action of the battery, it is capable of communicating strong and lasting magnetism to hardened steel bars and com- pass needles. Ifa steel bar be rubbed several times from end to end along the poles of the horse-shoe, lasting magnetism is communicated to the bar, exactly as could be effected by any other strong horse-shoe magnet. By touching the horse-shoe in a contrary direction, the magnetism of the bar may be de- stroyed, or the poles reversed at pleasure. In a similar way, strong magnetism may be impregnated in compass needles, or their poles reversed. | , It is a well known fact, that lightning often destroys the action of compasses on ship board; and even there are in- stances upon record of serious accidents being occasioned by the poles of compass needles being inverted by the electricity of lightning. Prudent navigators provide themselves often, on long voyages, with a set of magnetic bars, by means of which the strength of their compass needles, if impaired, or lost, may be restored. But it is possible, nay it is probable, — that the same stroke of lightning which destroys the magne- tism of the compass needles may also spoil that of the steel bars. A copper trough of modern dimensions, a zinc plate, ‘a little sulphuric and nitric acid, or, if that was considered too dangerous, some sal-ammoniac, and withall a soft iron wire, bent in the shape of a horse-shoe, and wound round with cop- per wire, would constantly insure the certitude of restoring magnetism on ship board. | After making these experiments, I was anxious to know if the power of the magnet was susceptible of still farther in- crease by augmenting the strength of the galvanic apparatus. A second trough, the acting superficies of which was about six square feet, was added to the first. The zinc plate of one trough was connected with the zinc of the other, as also the copper of the one with the copper of the other. Thus the Dr Moll’s Electro-Magnetic Experiments. 213 superficies brought to action was about seventeen square feet. But the horse-shoe magnet had acquired, it would appear, its maximum of strength, for its magnetic force was not materi- ally increased by this augmentation of galvanic power. I afterwards tried, with the same view, the powerful gal- vanic apparatus of Colonel Offerhaus, which I formerly de- scribed in Dr Brewster’s Journal.* But no increase of gal- vanic power was capable of increasing the strength of the magnet beyond a certain limit. Another iron wire, bent in the shape of a horse-shoe, and similar in every respect to that with which the preceding experiments were made, was surrounded with a spiral coil of brass twisted from left to right, (dextrorsum.) The effect was exactly the same as with copper wire, except that the spiral being wound to the right hand side, the north pole was, as iInight have been anticipated, on the side connected with the zinc. . A brass horse-shoe, wound round either with an iron, a brass, or a copper wire, did not show the least effect. . I did not, indeed, expect the least result from this experiment, which was made at the instance of a friend. It has been shown by the former experiments, that it is of little consequence whether a brass or a copper spiral be used. An iron spiral was tried in its turn, but the precaution was taken of coating the horse-shoe with silk. The iron spiral, wound to the left hand, was ;3,th mch in diameter; the weight of the apparatus about three kilogrammes, or six pounds, the iron, connecting the ends of the horse-shoe, about 1} pound. The apparatus thus arranged proved stronger than the former; it supported eighty-six pounds, or forty- three kilogrammes. Encouraged by these results, I increased the size of the horse-shoe, with a view of investigating whether any conside- rable augmentation of power might be thus produced. I had a horse-shoe prepared of about 124 English inches high, and 2} inches in diameter. A brass spiral of one-eight inch diameter was wound forty-four turns from right to left round this strong bar. The weight of the apparatus was about thirteen * Edinburgh Philosophical Journal, t. 6, p- 2. 214 Dr Moll’s Electro-Magnetic Experiments. kilogrammes, or twenty-six pounds. "The connecting bar of the apparatus weighed about four pounds. With an acting galvenic surface of eleven square English feet, the magnet sup- ported sixty-seven kilogrammes, or 135 pounds weight. The horse-shoe was afterwards coated with silk, and an iron spiral wire substituted for that of brass. The appara- tus then swpported 154 pounds, but I could not seein in making it carry an anvil of 200 pounds weight. It is well known that small magnets, generally speakinie are stronger in proportion to their size .than larger ones. I procured a small horse-shoe, coiled round with brass, and weighing in all two pounds. It supported about six pounds. Vallemont* relates that S. Augustine, was considerably alarmed and terrified, by witnessing some magnetic experi- ments, amongst which was a magnet supporting several iron rings, suspended from each other. The reverend father does not appear to have been deeply read in Greek philosophers and Latin poets, else he might have known, that the ex- periment which surprised him so much was known in the days of Plato, and described by Lucretius. S. Augustine would probably have been still more alarmed if he had seen magnets capable of supporting 154 pounds, formed in an instant, and their poles taken away or altered with the velocity of lightning. The poles of this large magnet were altered; restored, or destroyed with prodigious speed. It proved exceedingly well adapted to communicate a strong magnetism to bars of steel or compass needles. My next trial was, whether it wiih be ‘cn to increase the power of a common horse-shoe magnet of hardened steel. A magnet of this description, eight inches and a-half high, weighing about eight pounds, having lost much of its former strength, and capable only of supporting about five pounds, was twisted round with brass wire. It was exposed to gal- — vanic action during several hours, but its strength was not in- creased in the least degree. | I am far from supposing that the utmost force feats I was able to produce by galvanism is the limit of what may be * Vallemcat, Description de? aimant, qué sen formé a a pointe du clo~ cher neuf de N. D. de Chartres, p. 164. Dr Moll’s Electro-Magnetic Experiments. 215 done, and I am continually trying experiments, with a view of - increasing the magnetic force already produced. Atall events, it appears that the production by galvanism of a magnet ca- pable of supporting 154 pounds, is a curious fact, which a few years ago could be little anticipated. I took some pains to look over different books, in order to find accounts of large magnets, either artificial or natural; my trouble, however, was not well rewarded. I found but few and scanty accounts of large magnets. An old Dutch traveller and painter, Andrees de Bruyer, speaks of an immense natural loadstone, kept in the museum of Florence. Lalande, in his Voyage en Italie, gives some further account of this magnet ; but it is, as appears, unarmed, and therefore little can be said of its real strength. — One of the largest natural loadstones which I have seen is in the museum of Teyler at Haarlem. It commonly supports 150 pounds weight ; but the connecting iron piece, the dish on which the weight stands, &c. may be estimated at least at fifty pounds. Thus the ordinary weight which this loadstone sus- tains is 200 pounds. But Mr Van Marum asserts, that it is capable of carrying fifty pounds more, without dropping its load. The Teylerian loadstone, therefore, the largest at least in this country, carries 250 pounds. Another loadstone in the same museum sustains fifteen ki- _ logrammes or 30 pounds. A loadstone in the collection of the Society Felix Meritis ’ at Amsterdam carries fifty pounds or twenty-five kilogram- mes. The artificial magnets which were made by the Abbé Le- noble were celebrated in their time. The largest weighed nine pounds two ounces, and supported 105 pounds French poids de Mare. Galileo, in his younger days, applied himself much to the making of magnets; and Castelli, his pupil, speaks of one which weighed only six ounces, and supported fifteen pounds. Mr Park says* that one of the Emperors of China pre- sented to Toao V. king of Portugal, who reigned from 1750 to 1777, a large natural magnet carrying 200 pounds. * Park’s Chemical Catechism, p. 405. 216 Dr Moll’s Electro-Magnetic Experiments. Our countryman Dr Ingenhouss, made very small artificial magnets, carrying about a hundred times their own weight. _ Professor Allamand of Leyden had a magnet, supporting from 80 to 120 pounds. It is now in the collection of the Rotterdam Society of Arts and Sciences. Coulomb made artificial magnets, weighing ten kilogram- mes or twenty pounds, and supporting fifty kilogrammes or 100 pounds. ’ A certain Keilius or Keil, a German doctor, made, it is said, magnets of extraordinary power, supporting in some cases 250 pounds. A horse-shoe magnet of this man weighed, it is asserted, six pounds, and supported seventy pounds. ‘It appears from this that the magnet which I made by gal- vanic force was inferior only to that of the 'Teylerian Museum, that of the Emperor of China, and to that one which Dr Kei- lius is said to have made. Before the discovery of Dr Oerstedt, it was a matter of doubt among natural philosophers, whether any magnetism could be produced by galvanism. Now, magnets. nearly equal to the largest in existence are produced instantaneously by the mere pplication of galvanic power. When Dr Oerstedt first published his brillant discovery, it was observed by some that the new facts which were then daily brought to light, added very little to the stock of our know- ledge. It was said that these facts were unconnected with each other, and with any others previously known. I am_ very far from approving these views; and I am much more inclined to believe that the series of new facts discovered with- in the last years, clearly points out a more intimate connection between phenomena which formerly were held to be entirely independent of each other. Perhaps a few years later, and it will be generally known that many of these disjoined facts are produced by the same general cause. Since the days of Gilbert, it has been allowed that the earth acts on magnets near its surface, as one magnet on ‘another. Every one knows what is meant by the magnetism of the earth. Thus the globe of the earth acts as a system of magnets whose poles are placed in a certain determined position with respect to the terrestrial poles. Dr Moll’s Electro-Magnetic Experiments. 217 But a magnet, when acted on by galvanism, may be made — to revolve round its axis. May not, therefore, the revolution of the earth, of that immense magnet, be effected by galvanism by a similar cause ? Magnetic inclination and dectigusine: may be produced by galvanism. The magnetic needle is subject to inclination and variation on the surface of the earth. A magnet revolves on its axis when under the influence of galvanism ; the earth revolves also on its axis. The light produced by galvanism is unrivalled by any other artificial light. No argand or any other lamps, or gas light, can be compared to that emitted by charcoal placed between the poles of a large galvanic apparatus. The light of the sun alone is superior to it. Galvanic light ina vacuum will ex- tend itself to greater distances, and its appearance is strikingly similar to that of that light which is observed in the vicinity of the magnetic poles of the earth, of the aurora borealis. To complete the analogy, the emission of this polar light has an influence on the magnetic needle, which cannot be doubted after the repeated experiments of M. Arago. Would it be entirely absurd to suppose that aurora borealis is produced in those places where the galvanic force, which determines the rotation of the earth, is communicated to the globe ? No lamp nor gas-light acts on the Bolognese stone, nor on Canton’s phosphorus. ‘These bodies are imbibed with light only by exposure to the sun’s rays. But the same effect may be produced by exposing the Bolognese stone or Canton’s phosphorus to the action of galvanic or electric light. Thus galvanic light alone possesses this analogy with sun-light; and galvanic force is alone capable of producing on a smaller scale the same effects which are dependent on the action of the sun’s rays. - Since Mrs Somerville repeated Morrichini’s experiments, and pointed out the method of making them with certainty of success, it is scarcely possible to doubt the power of the sun’s rays refracted through a prism in magnetizing steel needles. Thus magnetism is alike produced by sun-light, and by galva- nic influence. ‘Therefore, it would not appear unreasonable to 218 Dr Brewster on the laws of doubt whether some analogy does it exist between the sun and that force which so strongly affects the magnetic needle. — I need scarcely mention how extended is the range of gal- vanic action in almost every part of chemical investigation. There is hardly one phenomenon known in chemistry which is not more or less connected with electro-magnetism. In every chemical action, the agency of that force is perceptible, which appears to prevade all nature, and whose influence seems to vivify the mutual action of existing bodies. Thus it would appear that the phenomena of galvanism, far from being dis- joined and unconnected with other classes of corpuscular action, may form the links of that chain by which the mutual action of bodies is joined i a Art. IV.—On the laws of the polarization of light by refrac- tion. By Davip Brewster, LL.D. F.R.S. L. and E.* In the autumn of 1813 I announced to the Royal Society the discovery which I had then made of the polarization of light by refraction ; + and in the November following I com- municated an extensive series of experiments which established the general law of the phenomena. During the sixteen years which have since elapsed, the subject does not seem to have made any progress. From experiments indeed stated to have been performed at all angles of incidence with plates of glass, M. Arago announced that the quantity of light which. the plate polarized by reflexion at any given angle was equal to the quantity polarized by transmission ; but this result, found- ed upon incorrect observation, led to false views, and thus contributed to stop the progress of this branch of optics. I had shown in 1813, from incontrovertible experiments, that the action of each refracting surface in polarizing light, produced a physical change on the refracted pencil, and brought it into a state approaching more and more to that of complete polarization. But this result, which will be presently demon- strated, was opposed as hypothetical by Dr Young and the * From the Phil. Trans. 1830., Read Feb. 25, 1830. + In this discovery I was anticipated by Malus. as 2 the polarization of light by refraction. 219 French philosophers; and Mr Herschel has more recently given it as his decision, that of the two contending opinions, that which was first asserted by Malus, and subsequently maintained by Biot, Arago, and Fresnel, is the most probable, _—namely, that the unpolarized part of the pencil, in place of having suffered any physical change, retains the condition of common light. I shall now proceed to apply to this subject the same princi- ples which I have already applied to the polarization of light by reflection, and to establish on the basis of actual experiment the true laws of the phenomena. The first step in this inquiry is to ascertain the law accord- ing to which the polarizing force of the refracting surface changes the position of the planes of polarized light,—a sub- ject which, in as far as I know, has not occupied the attention of any other person. If we take a plate of glass deviating so slightly from paral- lelism as to throw off from the principal image the images formed by reflexion from its inner surfaces, we shall be able to see, even at great obliquities, the transmitted light free from all admixture of reflected light. Let this plate be placed upon a divided circle, so that we can observe through it two luminous dises of polarized light A B, Plate II. Fig. 1, formed by double refraction, and having their planes of polarization inclined + 45° and — 45° to the plane of refraction. At an angle of incidence of 0°, when the light passes perpendicularly, the inclination of the planes of polarization will suffer no change; but at an incidence of 30° they will be turned round 40’; so that their inclination to M N or the angle a ec will be 45° 40’. At 45° their inclination will be 46° 47’. At 60° it will be 50° 7’; and it will increase gradually to 90°, where it becomes 66° 19°. Hence the maximum change produced by a single plate of glass upon the planes of polarization is 66° 19’ — 45° = 21° 19’, an effect’ waty | BD to what is produced by reflexion at angles of 39° or 70°. It is remarkable, however, that this change is made in the onpoas direction, the planes of polari- gation ‘now approaching to coincidence in a plane at right © angles to that of reflexion. This difference is exactly what might haye been expected from the opposite character of the 220 Dr Brewster on the laws of resulting polarization, the poles of the particles of light which were formerly repelled by the force of reflexion, being now attracted by the refracting force. In this experiment the action of the two surfaces is develop- ed in succession, so that we cannot deduce from the maximum rotation of 21° 19’, the real action of the first, or of a single surface, which must be obviously more than half of the action of the two surfaces, because the planes of polarization have been widened before they undergo the action of the second surface. In order to obtain the rotation due to a single surface, I took a prism of glass ABC (Fig. 2,) having such an angle BAC, that a ray R R, incident as obliquely as possible, should emerge in a direction Rr perpendicular to the surface A C. I took care that this prism was well annealed, and I caused the refraction to be performed as near as possible to the vertex A, where the glass was thinnest, and consequently most free from the influence of any polarizing structure. In this way I obtained the following measures. GLAss. Angles of Inclination of Pl b, cd, (Fig. 1. : an stoked me aa ahs Plane of mp won, Rotation. 87° 38’ s 54° 15’ r ‘ 9° | 5 54 50 - - 47 25 J ma A 32 20 - - 45 22 . . 0 22 I next made the following experiments with two kinds of glass,—the one a piece of parallel plate glass, and the other a piece of very thin crown. ‘The latter had the advantage of separating the reflected from the transmitted light. PiatE Guass. Crown Guass. Incidence. Inclination. Rotation. Inclination. Rotation. 0° 45° O/ 0° 0 45° 0 ee 40 47 28 2 28 47 18 , 218 55 49 35 4 35 49 19 4 19 67 52 53 7 53 52 16 7 16 80 58 53 13 53 58 42 13 42 86} 61 16 16 16 61 0 16 07 the polarization of light by refraction. 221 I was now desirous of ascertaining the influence of refractive power, although I had already determined in 1813, that a greater quantity of light was polarized, at the same angle of — incidence, by plates of a high than by plates of a low refrac- tive power. I experienced great difficulty in this part of the inquiry, from the necessity of having plates without any crys- talline structure. I tried gold leaf in a variety of ways; but I found it almost impossible to obtain correct results, on ac- count of the light which was transmitted unchanged through its pores. By stretching a film of soapy water across a rectangular frame of copper wire I obtained the following measure. WatTeER. Incidence. Inclination. Rotation. 85° 54° 17’ 9° 17 I next tried a thin plate of metalline glass of a very high refractive power. METALLINE GLAss. Incidence. Inclination. Rotation. 0° 45° Of 0° 0 20 45 42 0 42 30 46 50 1 50 40 48 0 3 0 55 51 12 6 12 80 62 32 17 32 From a comparison of: these results it is manifest that the rotation increases with the refractive power. In examining the effects produced at different angles of in- cidence, it becomes obvious that the rotation varies with the deviation of the refracted ray ; that is, with i — i the differ. . ence of the angles of incidence and refraction. Hence from a consideration of the circumstances of the phenomena I have been led to express the inclination ¢ of the planes of polariza- tion to the plane of refraction by the formula, Cot ? = cos (i — 7), the rotation being = = 9 — 45°. 299 . Dr Brewster on the laws of This formula obviously gives a nlinimum at 0°, and a maxi- mum at 90°; and at intermediate points it represents the ex- periments so accurately, that when the rhomb of calcareous spar is set to the calculated angle of inclination, the extraor- dinary image is completely invisible—a striking test of the correctness of the principle on which it is founded. The above expression is of course suited only to the case where the inclination # of the planes of polarization ad, cd, (Fig. 1,) is 45°; but when this not the case, the general ex- -pression is | Cot @ = cot 2 cos (i — 7.) When the light passes through a second surface, as in a single plate of glass, the value of w for the second surface is evidently the value of ¢ after the Ist refraction, or in general, calling ¢ the inclination after any number n of refractions, and 9 the inclination after one refraction. Cot 6 = (cot 9)” When ? is given by observation we have Cot 9 Le be d. The general formula for any inclination # and any number n of refractions is ‘Cot 6 -- (cot x cos (t — )" and n ae Cot 9 et ae x cos (i— ’.) And when # = 45 and cot # = J as in common light, Cot 6= (cos (¢— ) J". Cot 9 = v cos (i — @) As the term (cos (i — ‘)) can never Babli equal to 0, the planes of polarization can never be brought into a state of coincidence in a plane perpendicular to that of reflexion, either at the polarizing angle, or at any other angle. : In order to compare the formula with experiment, I took a plate of well annealed glass, which at all Lacan separates the polarization of Light by refraction. 223 the reflected from the transmitted rays, and in which m was nearly 1.510, and I obtained the following results. Angles of Angles of Rotation Inclination Inclination Difference Incidence. Refraction. observed. observed. calculated. ; 0° 0° 0’ re 4° 0 45 0 10 6 363 O18 .4518° .45 6 +'0° 7 20 18 5 027 4527 4525 402 25: 011615 032 45 32 45 40 —O0 8 30 19 20 040 45 40 46 0 — 0 20 35 22:19 Lig! 4612.5; 4425... «018 40 25 10 130 4630 4656 — 0 26 45 27 55 142 4647 4734 +40 47 50 30 29 248 47 42 48 24 — 0 42 55 33 52 354 4854 .48 59 —O0 5 60 35 0 52°70) 50 7 2 60.36 — 0 29 65° § 3653 648 5148 52 7 — 0 19 70 38 29 $3704.53. 7 53 59 — 0 52 75. 39 45. 955 5455 £5618 —1 23 80 40 42 1210 5710 59 5 — 1 55 85 4b 1% 1545 60 45 62 24 —1 39 86 41 21 1639 = 61 39 63 9 —1 30 90 41 28 66:19 The last column but one of the Table was calculated by the formula, Cot ¢ = (cos Bares i)’ n being in this case 2. The conformity-of the observed with the calculated results is sufficiently great, the average differ- ence being only 41’. The errors, however, being almost all negative, I suspected that there was an error of adjustment in the apparatus; and upon repeating the experiment at 80°, the point of maximum error, I found that the inclination was fully 58° 40’, giving a difference only of 25’ in place of 1° 55’. _ J did not think it necessary to repeat all the observations ; but I found, by placing the analyzing rhomb at the calculated inclinations, that the extraordinary image invariably disap- peared, the best of all proofs of the correctness of- the for- mula. 224 Dr Brewster on the laws of In these experiments # = 45° atid cot w@ = 1; but in or- der to try the formula when 2 varied from 0° to 90°, I took the case where the angle of incidence was 80° and 9 = 58° 40’ when # = 45°. The following were the results. Values of 2. Syaed. | ealeulated, difference, 0° 0° 0 0° 0 0° 0 Qs 7 10 7 20 —0 10 5 940 819 +7 21 10 17 10 16 2&5 +0 45 15 24 42 24 6 +0 36 20 82 30 31 19 4111 25 39 15 37 54 +1 21 30 44 10 43 57 +013 35 49 38 49 28 +0 10 40 54 36 54 31 4005 AB 58 40 59 5 —0 25 50 63. 10 63 19 —0 9 55 66 58 67 15 —017 60- 70 18 10 56 —0 38 65 74) 8 74 24 —0 16 70 16 56 17 42 —0 46 15 79. 20 80 53 wish 80 83 23 83 58 — 0.35 85 86 23 86 0 + 0 23 90 90 0 90 0 0 0 The last column but one was calculated by the formula, cot ¢ = cot #. (cot 58° 40’)?.. The differences on an average amount only to 36. | In determining the quantity of polarized light i in the re. fracted pencil, we must follow, the method already explained for the reflected ray, mutatis mutandis. The principal sec. tion of the analyzing rhomb being now supposed to be placed in a plane perpendicular to the plane of reflexion, the ayant ty of light Q/ polarized im that plane, will be : Q’ — 1— 2 cos %9, the quantity of transmitted light being unity. But . Cot 9 = cot z cos (¢ — ?’,) o_o the polarization of light by refraction. 225 sind cos= % and as cot 2? = pee and sin? 9 + cos? — 1, we have the quo- tient and the sum of sin? g and cos’ ¢ to find them. Hence (cot x cos (i — i) I+ (cot x cos ( — i’)? and by substituting this for cos? 9 in the former equation, it . becomes Cos? 9 = (cot xX cos {t — v”))? vb ene ary (cot x cos (t — iv)’ Now since by Fresnel’s formula the quantity of reflected light is , (sin? (6 — Vv) , tan? (¢ — 7’) Rat (as (@@ 4+ 7) ~ tan? (¢ + 7’) the quantity of transmitted light T will be | (= (¢— 7’) , tan? (i— 7”) Tie dined sin? (@ + 7)" tan? (@ + 7) Zz Hence sin? (i— 7’) | tan? (i— i’) > hs (: 14 (= G@ 2) tan? (4 HD | (cos (i — oy) —2 C FE (cos (: — ‘yy’ This formula is applicable to common light in which cot a = ] disappears from the equation ; but on the same principles which we have explained in a preceding paper, it becomes for partially polarized rays and for polarized light, in? (¢ 3 tant ee): v= (: —i nt (ED cos? x + pe rar sin? ‘)) ea. (cot x cos (i— i) ) ( Hing 1 + (cot x cos (i — #))° In all these cases the formula expresses the quantity of light really or apparently polarized in the plane of refraction. As the planes of polarization of a pencil polarized + 45° and — 45° cannot be brought into a state of coincidence by refraction, the quantity of light polarized by refraction can never be mathematically equal to the whole of the transmitted NEW SERIES. VOL. 11]. NO. Il. ocTOBER 1830. P ~ 226 Dr Brewster on the laws of pencil, however numerous be the xgfractions which it under- goes; or, what is the same thing, refraction cannot produce rays truly polarized, that is, with their planes of polarization — parallel. The preceding analysis of the changes produced on common light, considered as represented by two oppositely polarized pencils, furnishes us with the same conclusions respecting the ' partial polarization of light by refraction, which we deduced in a preceding paper respecting the partial polarization of light by reflexion. Each refracting surface produces a change in the position of the planes of polarization, and consequently a physical change upon the transmitted pencil by which it has approached to the state of complete polarization. This position I shall illustrate by applying the formula to - the experiments which I have published in the Philosophical Transactions for 1814. According to the first of these experiments, the light of a wax candle at the distance of ten or twelve feet is wholly po- larized by eight plates, or sixteen surfaces of parallel plate glass at an angle of 78° 52. Now I have ascertained that a pencil of light of this intensity, will disappear from the extra- ordinary image, or appear to be\completely polarized, provid- ed its planes of polarization do not form an angle of less than 883° with the plane of refraction for a moderate number of plates, or 883° for a considerable number of plates, the differ- ence arising from the great diminution of the light in passing through the substance of the glass. In the present case the formula gives - | 16 Cot d= Pein ) and é= 88° 50’; so that the light should appear to be completely polarized, as it was found to be. At an angle of 61° 0’ the pencil was s polarized by 24 plates or 48 surfaces. Here , Cot = (cos (¢—) y —'g9° 36". At an angle of 43° 34 the high was polarized by 47 pate -or 94 surfaces. Here the polarization of light by refraction. 227 Cot é= (8 Ga)" and 6 88° 2 i It is needless to carry this comparison any further ;) buit it may be interesting to ascertain by the formula the smallest number of refractions which will produce complete polariza- tion. In this case the angle of incidence must be nearly 90% Hence 9 = 56°29’ and (cos (i — #))°gives 88° 36’, ‘and (cos (— i)” 89° 4’ » that is, the polarization will be near- ly complete by the most oblique transmission through 43 - plates or 9 surfaces, and will be almost perfectly ee through 5 plates or 10 surfaces. _ Having thus obtained formule for the quantity of light polarized by refraction and reflexion, at becomes a point of great importance to compare the results which they furnish. Calling R the reflected light, these formule become (Sees). cos (2 — 7’) Q=h (1-2 ell vo) = )-and my (SS (¢— 7) gata (ie rena 1 + (cos (ti 2’) ) But these two quantities are exactly equal, and hence-we obtain the important general law, that,—At the first surface of all bodies, and at all angles of incidence, the quantity of light polarized by refraction is equal to the quantity polarized by reflection. I have said ‘ of all bodies,” because the law is equally applicable to the surfaces of crystallized and metallic bodies, though the action of their first surface is masked or _ modified by other causes. It is obvious from the formula that there must be some angle of incidence where R = 1 — R, that is, where the re- flected is equal to the transmitted light. "When this takes place, we have sin* 9 — cos? ¢, that is, ' The reflected is equal to the transmitted light, when ‘the inclination of the planes of polarization of the Wiected pencil to the plane of reflection, is the complement of the inclination of the planes of polarization of the refracted pencil to the same plane ;—or if we refer the inclination of the planes to the two 226 Dr Brewster on the laws of rectangular planes into which the "planes of polarization are brought,—The reflected will be equal to the transmitted light when the inclination of the planes of polarization of the re- flected pencil to the plane of reflection, is equal to the ineli- nation of the plane of polarization of the refracted pencil to a plane perpendicular to the plane of reflection. | In order to show the connection between the phenomena of the reflected and those of the transmitted light, I have given the following table, which shows the*inclination of the planes of polarization of the reflected and the refracted pencil, and the quantities of light reflected, transmitted, and polarized, at all angles of incidence upon glass, m being equal to 1 525, and the incident light = 1000. Inclination Inelination of Planeof of Plane of ity SORE Angles of | APGi@ OF “ Polariza- —_Polariza- Cay of Light ‘2 Incidence, oa tion of the tion of the Reflected, ahi Ve a as i’, " Reflected Refracted . R. ie R Light, Light, mest 9’. ?- ° ‘ ° / ° / / 0 0 0 0 45 O 45 0 43.23 956.77 0. 2 0 1 183 44 57 45 0.7 43.26 956.74 0.07 10 0 6 32° 43 51 45 3 43.39 956.61 1.73 20 0 12 58 40 18 45 13 43.41 956.59 © 7.22 o's. 2 pay wt 45 21 43.64 956.36 116 - 30 0 19 8} 33 40 45 31 44.78 955.22 17.24 35...0;.. 22, 6 . 29. 18 45 44 46.33. 953.67 24.40 40.0 24 56 23 41 46 0 49.10 950.90 32.2 45 0 27 874 17 224 46° 20 53.66 946.33 44.0 50 0. 30 ® 10 18 46 45 61.36 938.64 57.4 5645, 33 15, .0 .0 47 29 79.5 920.5 79.5 60 0 34 36 & 44 47 544 93.31 906.69 91.6 65 0 36 28 12 45 48 42 124.86 875.14 112.7 70.10... $8 «2s 18.82 49 28 162.67 $37.33 129.8 75 0 39 18 26 82 50 55 257.56 742.44 152.3 78 0 39 54 30 44 51. 48 329.95 670.05 157.6 78 7 $9 55. 80:43 51 50 333.20 666.80 157.65 79.0 40 4 81 $9 62 7 359.27 640.73 157.6 80 40 40 13 33 18 52 273 391.7 6083 156.7 82 4 40 35 36 22 53 264 499.44 500.56 145.4 84 0 40 42 $38 2 53 57 560.32 439.68 134.93 85 0 40 47 39 12 54 22 61628 383.72 Set 85. 50 40 502 40 12 54 44 666.44 333.56 111.11 86 0 0 51 40 22,5 54 48 676.26 323.74 7 87 0 0 54 41 32° 55 16 744,11 255.89 P| 88:0 40 57} 41 93 55 43 819.9 180.1 s9 0 4 58 43 41 56 14 904.81 95.19 36.3 900° * 40° 58° “45° (OO 56 29 1000 0 0 the polarization of light by refraction. 229 It is obvious from a consideration of the principle. of the formula for reflected light, that the quantity of polarized light is nothing at 0° because the force which polarizes it is there a minimum. At the maximum polarizing angle, Q is only 79 because the glass is incapable of reflecting more light at that angle, otherwise more would have been polarized. The value of Q then rises to its: maximum at 78° 7/, and descends to its minimum at 90°; but the polarizing force has not. increased from 56° 45’ to 78° 7’, as the value of g’ shows. It.is. only the quantity of reflected light that has increased, which occa- sions a greater quantity of light to disappear from the extra- ordinary image of the analysing rhomb. The case, however, is different with the refracted light. The value of Q’ has one minimum at.0° and another at 90°, while its maximum is at '78°'7’ ; but the force hasits minimum at 0° and its maximum at 90°, where its effect is a minimum only because there is no light to polarize. At the incidence of 78° ‘7’, where the quantities Q, Q’ reach their maxima, the reflected light is exactly one-half of the transmitted light ; sin? g’ = cos? ¢ and tan ¢’ = Cos 9. At 85° 50/ 40”, where the transmitted light is one-half of the reflected light, the deviation (¢ — #) = 45°; and the quan- tity of polarized light is one-third of the transmitted light, one-sixth of the reflected light, and one-ninth of the incident light. Sin? ¢ : cos? ? = reflected light : transmitted light, and cot g=sinG@— 7). At 45° we have (¢ + 7) + @— 7) = 90° and o = (it~), © (int: pall 7 )y (sin i #4)? At 56° 45’, the polarizing angle, the formula for reflected light becomes R = 3 (sin? (@— #))? but at this angle we have i = 90° —i%. Hence we obtain the following simple expression in terms of the angle of mcidence, for the quantity of light reflected by all bodies at the polarizing angle. R = 3 (cos 22)?. I have already mentioned the experiment of M. Arago with plates of glass, in which he found that “ at every possible in- clination” the quantity of light polarized by transmission was Tan (i— ¥) = — ae and tan (i — 230 Dr Brewster on the action of the second surfaces equal to the quantity polarized by reflexion. This conclusion _ he extends to single ‘surfaces; but it is remarkable that the . law is true of ‘single surfaces in which he did not ascertain it to be true, while it is incorrect with regard to plates in which he believes that he has ascertained it to be true. » As the con- sideration of this point does not strictly belong to the present branch of the inquiry, I shall reserve it for a separate com-. munication, ** On the action of the second surfaces of transpa- rent plates upon Light.” ison ALLERLY, December 29, 1829. ot} Art. V.—On the action of the second.surfaces of transpa- rent plates upon light... By Davin BRAYSTERy fobeo) Dx F. R..S. Lond. and Edin.* | Ix a paper on the Polarization of Light by Reflexion, om lished in the Philosophical Transactions for 1815, I showed that the Law of the Tangents was rigorously true. for. the second surfaces of transparent bodies, provided that the sine of the:angle of incidence was less than the reciprocal of the index of refraction. The action of the, second surfaces of plates at angles of incidence different from the maximum, — polarizing angle, was studied by M. Arago, who conducted, his experiments in the following manner. ‘*‘ With respect to this phenomenon,” says M. Arago,, Ka remarkable result of experiment may here be noticed ; that is, that in every possible inclination A = A’ +. *« Let us suppose that a plate of glass E D, Plate IT. Fig. 3. is placed in the position that the figure represents before a medium AB of a uniform tint; for 1 instance, a sheet of fine white paper. The eye placed at O, will receive simultaneously the ray 1O reflected at I, and the ray BI O transmitted at the same point. Place at m n an opaque diaphragm blackened, and perforated. by a small hole at S. Lastly, let the eye be furnished with, a doubly refracting Be be C, which affords two images of she aperture. ) ppd * From the Phil. Trans. 1830. , Read February 25, 1830. T A isthe light polarized by Feflepion, and A that polartzed by refraction. of transparent plates upon light. — ‘“< If now, by means of a little black screen placed between B and I, we stop the ray BI which would have been trans- mitted, the crystal properly placed will give an ordinary image = A + 3B, and an extraordinary image =} B. But if the screen were placed between A and I, and the ray A I were in- tercepted, we should still have two images of the hole, and their intensities would be 3 B’ and A’ + 3 B¥ respectively. Con- sequently, without any screen, if the whole of the reflected light AI O, and the transmitted BIO are allowed to arrive at the eye, we shall have for the ordinary image A + 5 B+ 3 B’, and for the extraordinary image } B + A’ + 3 B’. * Now it appears from actually making the experiment, that the two images are perfectly equal, whatever may be the angle formed by the ray A 1 with the plate of glass, which can only be because A is always equal to A’. Consequently << The quantity of polarized light contained in the pencil transmitted by a transparent plate, is exactly equal to the quantity of light polarized at right angles, which is found in- the pencil reflected by the same plate.” We have no doubt that M. Arago obtained these results, particularly near the polarizing angle, at which limit they are rigorously true ; but at all other angles of incidence they are wholly incorrect. When we consider, indeed, the nature of the experiment, which has been lauded for its elegance and in- genuity, we shall see reason to pronounce its results as nothing more than coarse estimates, in which the apparent equality of the two images is the effect either of imperfect observation or of some unrecognized compensation. If we make the experiment in the manner shown in Fig. 4, with a colourless and well annealed prism of glass E F D, in place of a plate of glass; and make the ray B I enter the sur- face F D perpendicularly at I, we get rid of all sources of error, and we obtain, what is really wanted, the result for a single surface. In this case the experiment is not disturbed ‘by the light reflected from the inner surfaces of the prism, which is all thrown off from the pencil which enters the eye. ° In M. Arago’s form of the experiment, part of the ray BI (Fig. 3,) undergoes reflexions within the plate, and there comes along with it to the eye, at O, a portion of light polarized in 232 Dr Brewster on the action of the second surfaces the plane of reflexion: in like marfher the part of the pen-— cil A I that enters the plate, undergoes partial reflexions, and the part reflected from the first surface carries along with it another portion of light. polarized in the plane of reflexion, so that four portions of light polarized in the plane of reflexion reach the eye, while only two portions reach it polarized at right angles to the plane of reflexion, viz. those which are po- larized: by the refraction of each of the surfaces of the plate. Now the part of the pencil A I which suffers a first reflexion from each of the surfaces of the plate, is, as we shall presently show, defective in polarized light compared with that which has experienced two refractions, so that it requires the above additional quantities to produce a compensation with the trans- mitted pencil BO. If this is not the true cause of the appa- rent compensation, that is, if M. Arago took means to exclude the reflected pencils which seem to have produced the compen- sation, we must then ascribe the equality of the two images to inaccuracy of observation. _ | But even if we admit that M. Arago’s experimental results are correct with regard to plates, it necessarily follows that they cannot be true with regard to surfaces; for it is obvious from the slightest consideration of the subject, that the phenomena of the one can never be interchangeable with those of the other. ~t) In order to demonstrate these views by an analysis of the changes which the intromitted light experiences from the two refractions and the intermediate reflexion of a transparent plate, I took a plate of glass of the shape M N (Fig. 5.) having an oblique face M d cut upon one of its ends. A ray of light R A, polarized + 45° and — 45°, was made to fall upon it at A, at an angle of incidence of nearly 83°, so that the inclination of the planes of polarization of the reflected ray A P was about 364°. Now the ray A C after reflexion in the directionC S, with- out anyrefraction at B, where it emerges perpendicularly to Md, would also have had the inclination of its planes of polarization equal to 363° if there had been no intermediate refraction at A; but this refraction alone being capable of producing an inclina- tion of 58° or a rotation of 538° — 45° = 8°, and this rotation being in an opposite direction from that produced by the second 3 : ; - of transparent plates upon light. 233 reflexion at C, the inclination of the planes of polarization for the ray C S is nearly 443°, the reflexion at C having brought back the ray AC almost exactly into the state of natural light. Without changing either the light or the angle, I cemented a prism M cd on the face M d, so that cd was parallel tod N, and I found that the second refraction at 0, equal to that at A, changed the inclination of the planes of polarization to 53°; that is, the two refractive actions at A and 4 had overcome the action of reflexion at C, and the pencil 0 s actually contained light polarized perpendicular to the plane of reflexion. _ In order to put this result to another test, I took a plate McN Q (Fig. 5.) of the same glass, which separated the pen- cil bs reflected at the second surface, from the parallel pencil AP reflected from the first surface, and I found that at an angle of 83°, the value of the inclination I, or 9, for the ray was about 373°, while the value of I for the ray bs was nearly 5B’, an effect almost equal to the refractive action of a plate at 83° of incidence. When the pencil R A is incident on the first surface at the polarizing angle or 56° 45’, the rotation produced by refraction at A is about 2°, or the inclination I = 45° 4+ 2° — 47°: but the maximum action of the polarizing force at C is sufficient to make I = 0° whether z is 45° or 47°. Hence C B is com- pletely polarized in the plane of reflexion, and the refractive action at 6 is incapable of changing the plane of polarization when I — 0°: the reason is therefore obvious why the two ro- tations at A and 6, of 2° each, produce no effect at the maxi- mum polarizing angle. If we now call 9 = Inclination to the plane of reflexion produced by the | Ist refraction at A, gy’ = Inclination produced by the reflexion at C, 9” = Inclination produced by the 2d refraction at 6, We shall have Cot 9 = cos (—7#); or tang= : cos (t— 7) cos(t+7’) cos (t+?) Tan?’ =tanv cos (i — i’) ~ (cos (i— v’))? 234 Dr Brewster on the action of the second surfaces (cos (¢—17’))? cos ( + 7) These formule are suited to common light where v = 45°, but when @ varies they become Cot 9 = cot x (cos (¢— 7) ) Tan ? = tang (= ae a to) cos (t — 2’))° Cot 9” = ( cot @ jesse a + os ). Resuming the formula for common light, viz. cot p" = (eog Geog (Fae) 1; it is obvious that *when (cos (¢@ —7#’) > = cos (t + 7’) cos (i + @’), cot ” — 1, and 9” = 45°; that is, the light is re- stored to common light. In glass where m = 1.525 this effect takes place at '78° 7’; a little below 78° in diamond ; and_a little above 80° in water. At an angle below this, 9 becomes less than 45°, and the. pencil contains light polarized in the plane of reflexion; while at all greater angles g is above 45°, and the pencil contains light polarized perpendicular to the plane of reflexion. Hence we obtain the following curious law. | « A pencil of light reflected from the second surfaces of transparent plates, and reaching the eye after two refractions aud an intermediate reflexion, contains at all angles of inci- dence from 0° to the maximum polarizing angle, a portion of light polarized in the plane of reflexion. Above the polariz- ing angle the part of the pencil polarized in the plane of re- flexion diminishes till cos (¢ + #) = (cos (t — #’) )°, when it disappears, and the whole pencil has the character of common light. Above this last angle the pencil contains a quantity of light polarized perpendicularly to the plane of reflexion, which increases to a maximum and then diminishes to zero at 90.” Let us now examine the state of the pencil C S that has suffered only one refraction and one reflexion. Resuming the cos (t + v) (cos (i —} “)y (i —7) )? = cos (i + 7), 9’ = 45°, and consequently the light is restored to common light. ‘This takes place in glass at an angle of 82° 44’. At all angles beneath this, the pencil con- Cot 9” = cot w (cos (i —7 ))= formula tan ¢ = 9 it is evident that when (cos of transparent plates upon light. 235 tains light polarized in the plane of reflexion ; but at all angles above it, the pencil contains light polarized perpendicular to the plane of reflexion, the quantity increasing from 82° 44 to its maximum, and returning to its minimum at 90°, By comparing these deductions with the formula and table for reflected light given in my paper On the Laws of the Polarization of Light by Refraction, the following approximate law will be observed. When (Cos (t — “) = cos(z +2) All the incident light is reflected. (Cos (i —7’) )? = cos (¢@+ ’’) Half the incident light is reflected. (Cos (i — 7) )® =cos (2 +7) convex surface, as we have already shown it to be in deserib- ing the sections on the Strada Nuova. The saddle-shape of this superposition likewise forbids the idea that the level of the country was once nearly that of the summit of the ridge, and that the lateral vallies have been the work of .subsequent excavation. But a more convincing objection may likewise be made to this. “Had the vallies been excavated subsequently to the deposition of the secondary tufa, none of that formation could have been found in those vallies; whereas it appears that the stratified pumiceous rock recommences at the base of the ridge on either side, so that the real section is such as is represented in Fig. 1, where the diagonal shading indicates perpositions, such as we might anticipate from successive eruptions from below, as described in the sequel. No. VIII.—Concluding View of the Volcanie Formations. 257 the unstratified rock, the horizontal lines the stratified. Such an arrangement can only, I conceive, be satisfactorily explain- ed by one mode of reasoning, namely, that the secondary stra- tified tufa (or pumiceous conglomerate, or rapillo, which are synonymous,) was first deposited under the ocean from craters likewise subaqueous in this neighbourhood, of which traces may or may not remain. ‘That these strata were not aggluti- nated we have no difficulty in explaining, and have no neces- sity to recur to the idea generally maintained, that these dry powdery conglomerates were ejected after the hills had been raised so high as to emerge from the water. This indeed fails to account for their obviously aqueous stratification. ‘The more obvious reason is, that in their very nature they are unsuscep- tible of agglutination, being almost wholly composed of fila- ments of pumice, and, if mixed ever so long with water, must still retain their harsh feel and incoherent structure. We hence derive another argument for the plausibility of our theory, for by all analogy such products are the first ejections of volcanic vents. When the pumiceous eruption had ceased, a liquid or mud eruption was, I conceive, the next phenomenon, which might either be caused by the admission of the sea water through the craters, or by any other natural agency into which we ‘need not inquire, but is amply supported by analogy. The expansive force of the steam accompanying this igno-aqueous ejection, aided perhaps by the hydrostatic pressure of the fluid mass elevated towards the previous crater, caused, as I imagine, numerous rents radiating from such craters, and through these was slowly ejected a plastic but coherent and amorphous mass of tufa, which, receiving at the same time a sedimentary deposit of rapillo, either actually in suspension in the ocean, or partly derived from the pre-existent strata, was slowly elevated by successive additions from below to its pre- sent height, the directions of the hills indicating the lines of fissure, and at their union or crossing forming perhaps the only true tufaceous craters of the neighbourhood. I may add, that by such an explanation alone can I account for the double species of stratification which occurs on the summit of Pausilipo, where some distortion occurring in the regular stra- NEW SERIES, VOL. III. NO. Il. ocTOBER 1830. R 258 Mr Forbes’s Physical Notices of the Bay of Naples. tification of the rapillo, and basins various shapes being thus formed, these are internally filled by perfectly horizontal layers unconformable with the troughs in which they lie. Such must have been deposited after the elevation was complete, and before the final recession of the waters. Until I had — brought my ideas on this subject into something of their pre- sent shape, I could find no satisfactory explanation of such appearances. Similar considerations may perhaps apply to such a structure occurring in non-volcanic countries, as in beds of coal. 3 By such reasoning, we throw aside entirely the almost itt surmountable difficulties of supposing the origin of the divid- ed volcanic matter to be necessarily from existing, and there- fore often very distant, craters, such as at Rome and Ander- nach. ‘To those who think it necessary to find the existing crater which may have produced every submarine cinéreous ejection, I would propose the following question, setting aside the idea of the crater being buried amidst its own subsequent tufaceous formations. The island of Sabrina off the Azores, was formed in 1811 by a submarine explosion of substances, which we may conceive quite similar to those of which rapillo is formed, and which likewise constitute the Monte Nuovo. This island rose 300 feet above the sea, and had a crater 500 feet in diameter.* Very speedily the whole was washed down by the sea, and can be conceived to have become nothing élse than beds of secondary tufa. It was below the surface of the ocean in a few weeks ; and some years after, its site was cover- ed by eighty fathoms of water. Can any reasonable man ima-' gine, that, if the land were elevated to sight, any msi: traces of a crater would appear ? I will only add one more argument in favour of the Heid ejection of unstratified tufa. Near Capo di Monte, and in other localities near Naples, a very peculiar structure in the tufa is observable, which I have not myself seen, but which — has been accurately described. + Certain veins of a decidedly dissimilar structure are observed cutting vertically through the * See this Journal, N. S. vol. ii. p. 84. | t Tenore, Essai, &c. p. 40; Scrope on Volcanos, p. 168 ; and a pajier by the same author in the Geol. Trans. N.S. vol. ii. 3 No. VIII.—Concluding View of the Volcanic Formations. 259 mass of tufa. These are considered by Mr Scrope as the mere result of the infiltration of finer particles in the adjoining rock into its fissures. But in my mind, phenomena so similar to dikes in trap rocks and veins in the Monte Somma, already discussed, must be consistently referred to a similar origin. To attribute them to infiltration is bordering upon an approach to the wak- ing dreams of the Wernerian School ; and though, from the confessedly semiaqueous origin of the rock, we might look upon it with some toleration in default of more plausible ex- planation, it appears to me, that it is so entirely what we might expect from a second eruption of tufa from below filling up the fissures of the first, as only to add a strong confirmation to that hypothesis. I have purposely avoided mixing up any account of Mr Scrope’s general theory in these remarks; because, though we nearly agree on some points, we greatly differ on others, and on account of the difficulties I have found in arriving at his exact opinion on the subject of volcanic tufa, partly from what I consider the bad arrangement of his book, and partly from the ambiguity, and, as it appears to me, the occasional contra- dictions of his expressions on the subject. Indeed, it is only latterly that I have been at pains to examine his ideas on the subject, and not until my own were fully formed. The follow- ing quotation from Mr Scrope’s paper on the Bay of Naples in the Geological Transactions, would appear (though it is not without ambiguities,) nearly to coincide in my views. ‘ The hard tufa of which the volcanic hills of the neighbourhood of Naples are almost exclusively formed, seems evidently to owe its coherence, like the trass of the Rhine, to a setting or aggrega- tive process which took place in a body of finely triturated trachyte intimately mixed with water, as that fluid drained off or was squeezed out by superincumbent pressure. In the formations under review this admixture with water appears to have been owing to the circumstance of volcanic rents having burst out under the level of the sea, though in so shallow a spot, that the accumulated ejections soon raised the cones to a certain height above the water level : in consequence of which, the ma- terials subsequently thrown up, falling dry on the surface of - the newly raised island, remained in a loose state. Every one of 260 Mr Forbes’s Physical Notices of the Bay of Naples. the hills in question is indeed covered to a greater or less depth by strata of loose tufaceous conglomerate, conformable, and sometimes graduating into the hard tufa below.”* In the first part of the extract we are disposed to understand the au- thor as speaking of mud eruptions, to which he expressly as- signs the origin of these rocks in another place.+ Yet the lat- ter part is totally at variance with such a supposition ; and, by considering the different state of aggregation, as owing solely to the fragmentary ejections falling above or below water, he merges into the hypothesis of Dolomieu, Brocchi,.&c. He is also tied down by the same difficulty which affected these observers,—the want of neighbouring craters in many, places; for the hypothesis of protrusion from below, explained above, interferes with the most remarkable peculiarity of Mr Scrope’s geological creed, the rejection of the theory of the elevation of horizontal strata round volcanic foci, and of the erhebungs cra- tere of Von Buch,—an hypothesis which it has been seen I con-= sider essential to the explanation of observed facts. Without it I consider Mr Scrope’ s idea of the origin of the incoherent rapillo as totally untenable; for he imputes its existence to ‘the fact of its being deposited above water, whilst the great consolidated body remained below. How comes it, then, that the rapillo is, as he admits, conformably stratified with the: tufa? that, instead of assuming those characters supposed to. be owing to the height of the waters of the ocean along a per- fectly horizontal line of demarcation, it not only dips on either side of the ridge of Pausilipo to a level much inferior to that which the solid tufa attains at the centre of the hill, but rises. with it along its dorsal ridge, as it ascends to meet the lofty: crateriform summit of the Camaldolii—My explanation of the fact is far more universal, and sets out on a matter of observa-: tion, which Mr Scrope seems to deny. Speaking of the loose tufa of the Phlegrzean fields, in contradistinction to the harder. nucleus, he says, that it is ‘* identical in composition with the. other, and differing only from it in the incoherence of its parts."{ Yet he himself admits that the solid tufa is entirely * Geol. Trans. N. S. ii, 361. vy . +t Consid. on Volcanos, p. 168. + Ibid. p. 176. No. VILL—Concluding View of the Volcanic. Formations. 261 composed of ‘ fragmentary trachyte,” while I presume none will deny the characteristic ingredient of rapillo to be frag- mentary pumice. In this difference I see the explanation of the facts wholly independent of the manner of ejection. The felspathose trachyte disintegrating into clayey matter was easily rendered coherent in the very submarine position, which could have no similar effect on the siliceous aecingee of pu- mice. * | Mr Scrope appears to me even Joss happy and more contra- dictory in his theory of the external arrangement of submarine voleanic formations,—a subject upon which I can here spend only a few words.—We have already seen, that, in the days of Breislak, any appearance of curvilinear continuity in the tuface- ous hills of this district was considered aniple evidence of a crater. But a growing disposition in geologists to deduce causes from the observed internal structure of the globe soon pointed out that a crater must always be surrounded with strata, of which a vertical section would have indicated corresponding inclined lines on either side of the crater, which produced, would give the section of a perfect cone. Forwhether these walls of the crater were raised by successive eruptions, or by the elevation of pre-existent strata, they must necessarily assume the virtual form of frusta of cones. Cones formed in the first mode, must necessarily have circular bases from the dispersion of ejected materials being the same in all directions, the quan- tities of matter and distance from the centre of ejection assum- ing a proportion dictated by the laws of gravity. Should a se- ries of contiguous craters eject materials, or should these merge into a rent, a ridge will be formed with not a saddle-shaped , but aconical stratification, having an ovoidal base, and the strata must be discontiguous at top. By confounding this very im_ portant distinction, Mr Scrope, while he has ‘successfully ap- plied his theory to the natural sections of the Capo de Miseno, * I have to notice an oversight in the Sixth Number of these Notices, where I spoke of the Rapillo of the Hill of Pausilipo as identical with Pozzuolana. Now Pozzuolana has characters such as to render its strati- fication by water almost impossible, since its peculiarity consists in its che- mical action with this fluid. It is therefore most likely, as I there sug- gested, that the real Pozzuolana, such as that of the Bay of Baja, was de- posited in dry beds, and never subjected to the direct action of water. 262 Mr Forbes’s Physical Notices of the Bay of Naples. the island of Nisida, &c.—which, so far from resembling the unstratified tufa of which the ranges of volcanic hills in the neighbourhood are formed, are confessedly and obviously stra- tified,—-would lead the reader into a similar explanation for the great masses of volcanic products which connect these few and insulated craters.* Neither the crater of Miseno or Nisi- da, (which are the two best defined of this class) could have exerted any material energy on the overpoweringly greater masses connected with them, and they are regular and simple voleanic cones ; a section of which, if taken through the axis of the cone, would be a triangle with a re-entrant curve substi- tuted for the apex, and, if the section be taken further from the axis, will be an hyperbola. Now it is from the latter configura- .tion that Mr Scrope would have us to apply his reasoning to a semicylindrical ridge like that of Pausilipo, where any one who chooses to consult a map for its form must see that it is de- monstratively impossible for such a hill to have been formed in the supposed manner, unless a series of craters had existed all along the top, which the very acknowledgment of the form of the stratification renders impossible. It would thus have had the form shown in Fig. 2, the embouchure above continu- ing along the top of the hill ; or, on the hypothesis of Breislak, only half of this remaining, as in Fig. 3, which is conceived to be the section of one wall of a great crater. How far these are from the reality, may be seen by comparing them with Fig. 1. But perhaps it will be said, that the ridge was deposited in the ejection of solid matter from the crateriform summits near the Camaldoli, which crowns the rising form of the hill: Yet here again we are beset by the insurmountable difficulty of the well-defined form of the ridge rising from the plain on either side, wholly irreconcileable to the idea of being part of a real cone, and depending upon that fact for its form of stratifica-_ tion. But, again, will it be said that this is only a slip of the pri- mitive cone insulated by the action of torrents or other causes. Here the form of the investment of rapillo, upon which Mr Scrope lays the whole force of discrimination of a volcanic mountain, completely interferes, not to mention the unnatural- ness of such a dorsal range being preserved, as well as that the * Geological Transactions, ut supra. No. VIIL.—Concluding View of the Volcanic Formations. 263 existence of pumiceous conglomerate in the adjoining vallies, ex-_ cludes the idea of the action of torrents. I must, therefore, con- sider as wholly untenable, the opinion that the eccentricity of the axis of volcanic accumulations produced by one vent, may be indefinitely increased ; and in the idea of a chain of craters, the external conformation must be shown to be consistent with such a supposition, which I imagine would not be found either in Pausilipo or the contiguous and similar ridges. I am of opinion that Mr Scrope’s theories on this subject require re- consideration and condensation ; I have intentionally misrepre- sented none of his statements, but there is a degree of ambi- guity and want of connection about them which renders them difficult to apprehend. As to the Geological epoch of the Tufas of a nature: similar to those of the Bay of Naples, we must judge by their includ- ed organic remains: They are for the most part intimately connected with living species. Bivalves of the genus Venus have been found at Naples,* and the Venus Islandica at Montalto,+ Cardiwm edule in Sicily. Near Naples have been enumerated specimens of the genera Ostrea, Cardium, Bucci- num and Patella, differing in nothing from those at present inhabiting the waters of the Bay.{ ; Near Rome bones and grinders of the fossil elephant are found in the tufas as well as in the alluvium.§ Wood is frequently imbedded in this rock, not only at Naples but near Rome and in Iceland ; it is monocotyledonous, and Tenore has ventured to put upon some specimens he has seen the name of the Agave Americana, which still flourishes.in the soil. I need hardly mention a statement of Breislak’s, that he had heard of human bones being found in the tufa in the kingdom of Naples at a depth of '76 feet. As the event occurred at a considerable distance of time we must, I am afraid, be content to reckon these among the pseudo-human bones which before the commencement of this century bewildered geologists. For as an Italian geolo- * Tenore. + Brocchi. $ Scrope, Geol. Trans. N. S. ii. 350. § Brocehi, Suolo di Rene) 179. I have in my possession a portion of a tusk dug from the alluvial bed of the Anio when I was there in 1827. 264 Mr Forbes’s Physical Notices of the Bay of Naples. gist forcibly says in similar. circuni$tances, “ trista cosa é il dovere ragionare su relazioni di uomini inesperti.” All these facts, however, prove that the oldest tufaceous formation was posterior to the deposition of tertiary rocks; in other quarters, however, coeval with them, as their interstratification proves. What I have called primitive tufa chiefly exists in the vi- cinity of Naples. The great plains which appear to have owed their origin to the volcanos of that hilly district, extend toa great distance, and are probably but fragments of more exten- sive deposits. ‘The Ponza islands appear to be remnants of a stretch of similar formations, which may have one day united with those of Albano and Rome, and to the origin of which some intermediate vents, as those near Sessa, the ancient Sues- sa Auruncorum, and Velletri may have contributed. Succeeding the tufas in date may probably be reckoned the trachytic rocks; of these we have some notable examples in Ischia, in the Phlegreean fields, and at Sorrento. It has been well observed by Mr Scrope, that, as a volcanic vent, Ischia is contrasted with Vesuvius by its trachytic ‘character, and in all probability it had much the earliest date, though we can infer nothing from historical records, since, notwithstanding the ample evidence we have of the violent commotions of the Ischian volcano at a period long preceding that of the first eruption of Vesuvius within the memory of man, the latter we. know must have owed its existence to long anterior action, and actually exhibited external marks of its origin before the eruption under Titus. This accounts for the very distinct aspects of these two volcanic vents embracing the region which | we have attempted to describe. In the intermediate space several intimations of similar protrusions appear, which, as far as we can judge from external appearances, were probably ejected like the trap rocks through the superincumbent mass of tufa. Of this description is the Piperno of the hill of the Camaldoli.* It might be worthy of inquiry whether this elevatory action of vast masses of trachyte was not the cause of the emersion of the tufaceous formations from their sub- marine condition. | The trachytic series is altogether extremely varied and com- * See this Journal, x. 254 ; and see Note E. No. VIII.—Coneluding View of the Volcanic Formations. 265 plex in the Bay of Naples, and different varieties of it may probably belong to very different epochs. We have it purely felspathose, or including augite, or quartz, compact, porphy- ritic, vesicular, or conglomerated as in the Monte di Procida. Volcanic clinkstone, which occasionally occurs, may also pro- bably be included under the trachytic class; such we have mentioned as occurring in the Monte Nuovo and in Ischia. There are many transitions from the real trachyte to mo- dern lavas, and these we waturally find in spots which indi- cate an intermediate period of activity, such as Astroni and the Solfatara, especially the latter. ‘The Monte Olibano de- scending from the crater of the Solfatara to the sea, which has already been described, partakes remarkably of this interme- diate character. As they must necessarily depend greatly upon the funda- mental formations, the characters of modern lavas are differ- ent according to the spots from which they issue. The coulées of the island of Ischia are more refractory than those of Vesu- vius, and the characters of the latter are essentially the same as the ancient products of the same source of which the houses in Pompeii were built, before being overwhelmed by the first eruption which history records. The original lavas, too, of the Monte Somma demand attention, and by their remarkable configuration afford hints for the interpretation of other natu- ral appearances. Finally, the frequent eruptions of Vesuvius, if their number renders them often less imposing, that very moderation contributes to their value as scientific lessons. It opens an ample field to the natural philosopher, the geolo- gist and the chemist ; and if, as we may hope, the problem of voleanic action be one day solved, in all likelihood’ Mount Vesuvius will be the most fertile source of information. ‘I'he researches of Davy have opened the way in this career by a series of well conducted and really analytic experiments, and, it may safely be affirmed, amidst the daily increasing perplex- ities which accompany the progress of geological inquiry, that the action of heat and its effects upon the mineral forma- tions is one of the most important objects of investigation, as well as most reducible to inductive research,—important, be- cause the extent of its influence is daily more acknowledged,— 266 Mr Forbes’s Physical Notices of the Bay of Naples. and sure, because we may compare’ ancient results with still existing causes of formation, which cannot be said of any others of the great rocky strata of our globe. It was once my intention to have enlarged these Notices with some details of other subjects connected with physical geography, particularly as to climate. But the strictly topo- graphical details which have, more than I proposed, filled these pages, would render any synopsis of other physical topics which could come within the limits I proposed to myself, but an imperfect and unconsolidated appendage. I shall there- fore content myself with inserting a few facts in a Note,* among those which I shall now subjoin in illustration of the preceding series of papers. . NOTES ON THE PRECEDING PAPERS ON THE Bay or NAPLES. NOTE A. (No. I. Vesuvius.) Vol. ix. p. 193. On the size of the crater before the erwption of A. D. '79. The size of a circle, of which the present ridge of the Monte Somma forms a part, would not have been so enormous as I once supposed, though sufficiently large to leave my opinions on the hypothesis here referred to unchanged. From an ac- curate projection upon Breislak’s large map of Vesuvius, I find the radius of curvature of the ridge of the Somma to be 1,45 Italian or geographical miles, and the arc subsisting 120.° Still the area of the crater must then have been nine times greater than at present, yet it is now perhaps the largest in existence. On the subject of the dikes in the abrupt face of Monte Somma, I may refer to the following works: Sir James Hall on the Strata near Granite, Edinburgh Transactions, vol. vil: Necker de Saussure, Mémoires de la Societé Naturelle de Geneve, tom. ii. and Geological Transactions, vol. iii. * See Note L. + It reflects no honour on the pains taken in the public libraries of Edin- burgh to preserve complete sets of Transactions which few individuals pos- sess, that this volume, coutaining M. de Saussure’s Views on Tufa, which I had also wished to see, is not to be found in the Libraries of the University, the Faculty of Advocates, or the Royal Society. Notes. < @a7 NOTE B. | Vol. ix. p. 206, and vol. x. p. 186, On the volcanic sand of Vesuvius. The chemical composition of this finely divided matter is extremely complex, and_ likewise very variable ; hence it has of late years occupied a good deal of attention. The assertion, that gold has been detected as a component part, I took from an Italian work, and mentioned in the first of the above cited passages, but having found an express contradiction of it in Humboldt’s Tableauzx de la Nature, upon such authority as Monticelli and Covelli, and Rose, I took the earliest opportu- nity of correcting it in the succeeding number. Since that period, however, a more detailed account of the matter has been given by Lavini, an Italian chemist, in the Turin T'rans- actions, * who has cited a sufficient number of analyses to show, that not only the materials of the volcanic dust of different eruptions greatly vary, but also of the same one. As his results are curious, and also throw light upon the oc- currence of native metals in this form, I shall here cite them. Eruption of 1794. Lavini. Eruption of 1822. Lavini. Bituminous vapour of water, 2.15 Water, - Sulphate of lime, - 2.00 Muriatic acid, - bus Muriate of Soda, - 1.00 Muriate of ammonia, - Lime, - “ 2.00 Sulphate of Lime, - 6.50 — Oxide of copper, - 10.00 Muriate of Soda, - 1.50 Alumina, - - - 8.15 Lime, - - ~ 2.07 Tritoxide of Iron, ~ 9.00 Oxide of Iron, - 13.50 Magnesia, - - 2.00 Alumina, - - 15.00 Silica, ~ - 68.00 Magnesia, - - - 1.50 Loss, “ on 0.79 — Silica, 3 : 53.50 —- Carbon, - - - 2.10 100 Loss - - - 1.20 100 The following lists contain a view of the constituents found by different chemists in the voleanic sand of 1822, which pre- sent so much diversity as to render us scrupulous about re- jecting the assertions of any one observer as to the traces of simple substances which he may have detected. Vauquelin.—1. Silica; 2. alumina; 3. oxide of iron; 4. mu- * Memorie dell’ Academia reaie della Scienze di Torino, tom. xxxiii. t 268 Mr Forbes’s Physical Notices of the Bay of Naples. riate of ammonia ; 5. sulphate of lime; 6. sulphate of potas- sa; 7. copper; 8. manganese ; 9. carbon; 10 lime. Lancelotti.—1. Sulphate of lime ; 2. muriate of ammonia ; 3. muriate of soda; 4. sulphate of soda ; 5. sulphate of alu- mina ; 6. vegeto-animal matter; 7. a trace of ammoniacal salts ; 8. subcarbonate of peroxide of iron; 9. alumina; 10. silica. Pepe.—1. Sulphate of potassa ; 2. sulphate of soda; 3. we sulphate of alumina; 4. subsulphate of lime; 5. subsulphate of magnesia; 6. muriate of potassa; 7. muriate of soda; 8. alumina; 9. lime; 10. silica; 11. magnesia; 12. tritoxide of iron; 13. antimony; 14. trace of gold; 15. trace of silver. Lavini.—1. Sulphate of lime; 2. muriate of soda: 3. lime; 4. oxide of iron; 5. alumina; 6. magnesia; 7. silica; 8. car- bon; 9. water; 10. muriatic acid ; 11. muriate of ammonia. NOTE C. Vol. ix. p. 212. . Veswvian Minerals. I am not going to attempt to improve this extremely imper- fect paper. But it may not be altogether without interest to enumerate the principal new minerals discovered by Monticelli and Covelli, and described by them in their Prodromo della Mineralogia Vesuviana, which have not found their way, I believe, into any Scottish Journal at least.* Humboldtilite. Primitive form, a rectangular prism with 2 a square base. Sp. gr. 3.104. Scratches glass. Colour, brown. Lustre vitreous. Translucent. tay Zurlite. Avvariety of the last. Sp. gr. 2.274. Scratched by the knife. Asparaguscoloured. Lamellar. Davina or Davyne. A variety of nepheline. Primitive form, hexahedron. Colour, brown, white. Lamellar. Usu- ally occurs in prisms of various forms. Sp. gr. 2.25. See this Journal, No xiv. p. 326, and No. ii. N. 5. p. 368. Cavolinite, nearly resembles Davyne. Cristianite. Primitive form, oblique cndaninlar prism, Sp. gr. 2.77. Scratched by quartz. Colour, brown, yellow, reddish. Biotina. Somewhat similar to the last. Scratches glass. Lustre vivid. Sp. gr. 3.11. " These notices are from Silliman’s Journal, Oct. 1826. Notes. 269 Foliaceous copper. Very delicate sublimations of copper. Breislakite. In appearance a brownish or reddish-brown down. Seen by the microscope in acicular crystals. It is found in the lava of La Scalla, at Olebano and Pozzuoli. It consists of silica, alumina, and a little iron. I shall make no farther additions to this paper, the subject of which would alone require volumes. I must take this op- portunity of acknowledging the compliment which that excel- lent mineralogist, Professor Leonhard, has paid me, by trans- lating this and the succeeding notices into German in his Zeitschrift fiir Mineralogie. The only one which I have seen is a neat abridgement of No. ii. On Pausilipo, &c. NOTE D. (No. II. On the Buried Cities,) Vol. x. p. 120. On the Silence of Pliny respecting the fate of Pompeii. In the Bibliotheque Universelle for 1829, where the greater part of this paper has been translated, I find the following annotation. ‘* Ce silence est, ce me semble, facile & expliquer. - Pline ecrivoit & son ami Tacite qui lui avoit demandé la rela- tion de la mort de son oncle; il ne devroit done entrer dans les details qui se n’atachoient a cet evenement particulier ou a la nature du phenomene. Lensevelissement d’Herculaneum et de Pompeii n’etoit certainement pas ignoré de 'Tacite, et Pline n’avoit qui faire de lui en parler.” (R.) NOTE E. (No. III. On the District of Pausilipo, &c.) Vol. x. p. 254. On the rock called Piperno. This species of trachyte, for such it must be considered, is sufficiently characteristically described in Mr Scrope’s memoir in the Geological Transactions, which has been published subsequently to the article before us. Since writing it I have also had occasion to remark a structure very similar to that here described in the felspathose trap rocks of the eastern Pentland Hills, near Edinburgh, where the augite displays a similar concretionary separation. It appears both in patches and cavities in the felspar basis, having an elongated form ex- actly as described in the case before us, and presents so much of a fused appearance, as might readily give Breislak the idea of its being pitchstone. This striking similarity will give some 270 Mr Forbes’s Physical Notices of the Bay of Naples. assistance in determining the true geological place of this rock, and will likewise give us reason to suppose, as. was hinted at in the text, that, like the trap rocks, it was protruded rere the superincumbent mass of tufa. NOTE F. (No. IV. On the Solfatara.) Vol. i. N.S. p. 133. On the connection of the Solfatara with Vesuvius. On this point, and on the interesting question of the sub- terranean cavity before the area of the Solfatara, on both of which I have in this paper strongly expressed my opinion, I have the satisfaction of being able to cite the authority of Sir Humphry Davy, a philosopher whose sober judgment so ad- mirably tempered his ingenious sagacity, as to render even his hypothetical deductions highly valuable. He observes : “‘ There is no question but that the ground under the Solfaterra is hollow, and there is scarcely any reason to doubt of a sub- terranean communication between this crater and that of Vesu- vius. Whenever Vesuvius is in an active state, the Solfaterra is comparatively tranquil. I examined the bocca of the Sol- faterra on the 2ist of February 1820, two days before the eruption of Vesuvius was at its height. The columns of steam, which usually arise in large quantities when Vesuvius is tran- quil, were now scarcely visible; and a piece of paper thrown into the aperture did not rise again, so that there was every reason to suppose the existence of a descending current of air.* The subterraneous thunder heard at such great distan- ces, under Vesuvius, 1s almost a demonstration of the existence of great cavities below filled with aeriform matter, and the same excavations which in the active state of the volcano throw out during. so great a length of time immense volumes of steam, must, there is every reason to believe, in its quiet state, become filled with atmospheric air.+-” * In 1814, in 1815, and in Jan. 1819, when Vesuvius was comparatively tranquil, I observed the Solfaterra in a very active state, throwing up large © quantities of steam and some sulphuretted hydrogen.—Davy. + Sir Humphry Davy on the Phenomena of Volcanos, Phil. Trans. 1828, Part. i, Notes. * Sa NOTE G. (No. V. On the Temple of Serapis.) Vol. i. N. S. p. 275. On the Theory of De Jorvo. Some time since, I had, through the kindness of Dr Hibbert, - an opportunity of consulting De Jorio’s work on the Temple of Serapis, which, at the time of writing this paper, I had failed of seeing by any means. I happened at the time the work was in my hands to be so engrossed by other objects, that I had not leisure to do more than glance over it. JT saw enough, however, to be made aware of a fact to me most un- expected, that this author does not support the lacustrine hypothesis, which, in the: paper to which this note refers, I had taken considerable pains to refute. I had conjectured that De Jorio was of this opinion, (p. 295, note,) because, in his work upon Pozzuoli, he speaks in general terms of the pholades inhabiting a “ laghetto” or small lake, and because Dr Daubeny, in quoting’ the author, expressly infers him to support the idea of the lake being separated from the sea, and at a higher level.* But, from what I saw of De Jorio’s work, I believe I am correct in asserting, that his ‘ laghetto” was nothing but a small arm of the sea, which, communicating with it, retained the same level; and he therefore supposes a real change in the relative level of the Temple and the sea exactly as I have done. Indeed, it give me very unexpected pleasure to observe, that, while I thought I was going direct- ly against the Canonico De Jorio, we seem (with the exception of his supposition that the temple was duit under high water mark,) to have been pursuing almost the same course, derived from similar data ; a circumstance highly confirmatory of any hypothesis supported without collusion. NOTE H. (No. VI. On the District of the Bay of Baja.) Vol. ii. N.S. p. 77. On the formation of the Monte Nuovo, &c. . It is sometimes not uninstructive to notice the gross mistakes which, at no very remote period, might be made by respectable and even distinguished travellers without imstant detection,— a lesson more peculiarly to be impressed upon those who visit less explored countries, with an imperfect acquaintance, or to- tal ignorance, of the languages and customs of the natives, but * Volcanos, pp. 163, 164. 272 Mr Forbes’s Physical Notices of the Bay of Naples. which might with advantage be attended to by the multitude of superficial travellers who at present overrun Europe, and encumber the press with their ill-digested lucubrations. I. chanced lately to look into the travels of no less a man than Bishop Burnet, where I found within a few pages such a mass of errors, as might well have been distributed through the whole work. The following singular fancy respecting the origin of the Monte Nasivo: is sufficiently striking ;—“* The Sulfatara is a surprizing thing ; here isa bottom out of which the force of the fire that breaks out still in many places ina thick steaming smoke that is full of brimstone, did throw up about a hundred and fifty years ago, a vast quantity of earth, which was carried above three miles hence, and formed the hill called Monte Novo.”* It is rather extraordinary to hear such an account at a distance of time from the event,—only half of that which has now elapsed. The Bishop tells us that he paced the Grotto of Pausilipo, and found it 440 paces. I found it to be 777 yards by pacing, which differs only three from the measured length reduced to English feet, which is 23225 Bishop Burnet must therefore, by his own account, have step- ped out more than five feet. I will not quote any more of the errors which may be found within a page or two of those just cited. They manifest a want not only of natural history and of ordinary observation, but of classical information. | He is, however, accurate upon one point on which the writers of the last century were extremely ignorant,—the depth of Lake Avernus, which, it is rather remarkable, should, at so early a period, have been accurately fathomed, and yet, till within a few years, have retained its mysterious character. Bishop Burnet states its depth at 18 fathoms or 108 feet; and we have seen (No. vi. p. 86,) that Captain Smith has determined it to be 102 feet. NOTE I. (No. VII. On the Islands of Procida and Ischia.) Vol. ii. N. S. p. 342. On the origin of Serpentine. The remarks which in this paper the very curious fact of the occurrence of serpentine in Ischia induced me to “ Letters on Switzerland, Italy, Sc. written in 1685, and 1686. Amster- dam Edit. 1687, p. 216. Wotes!. \oriag i ¢ | 273 throw out on the origin of that remarkable rock, were rather intended to direct the attention of geologists to some singular coincidences which its occurrence in this volcanic spot presented, “than to hold up as a fact, that the particular specimens in question owed their formation as well as their position to volcanic action. The facts connected with its geognostical situation were indeed so curious as to induce me to examine the authorities for and against the igneous origin of the rock ; but its remarkably fine mineralogical character seeming to point to a primitive, prevented me from assigning to it with any confidence a volcanic formation, though I am much dis- posed to believe that it has passed through the voleanic fo- cus, and owes its present situation to that agency. In fact, after bringing together the authorities for the igneous produc- tion of the rock in general, an opinion which I am at present disposed to entertain, I added, as to the immediate instance in question ; “‘ but even if we should not be disposed to admit its presence as an indigenous rock (meaning in this case igni- genous,) it may at least have been elevated by volcanic explo- sion from the deep-seated bases of the Apennines, which, in different parts, as Lombardy, Tuscany, Calabria, and Sicily, display this rock in remarkable perfection.”—-Pp. 343, 344. . I quoted in page $42, a remarkable instance of the volcanic occurrence of serpentine, said to be recorded by Sir George Mackenzie m his account of Iceland. Since writing this paper, Dr Brewster has communicated to me a letter from Sir George Mackenzie, pointing out the mistake into which T had fallen, and stating that his T'ravels in Iceland contained no account of serpentine in the mountain of Akkrefell. I greatly regret this mistaken report of Sir George’s observations, as I now find it to be, but, at the same time, I fear that the source in which the error originated must have done much more harm than any inadvertence of mine could produce. T took the state- ment from a paper of Brongniart’s, on the serpentines of Italy, translated in M. de la Beche’s volume of Foreign Geological Memoirs. In this work the passage runs thus + Sir G. Mackenzie states, that the volcanic amygdaloid beds of ithe mountain of Akkrefell in Iceland are traversed by veins of serpentine of more than a metre (about 3 feet. 33 inches,) NEW SERIES, VOL. III. NO. If. ocTOBER 1830. _ s 274 Mr Forbes’s Physical Notices of the Bay of Naples. in thickness.” After having the mistake pointed out to me, I was anxious to investigate its souree, and referred to the ori- ginal paper of M. Brongniart in the Annales des Mines. To. show that the translator was not in fault, I shall quote the ’ words of the distinguished French geologist himself :—* M., Mackensie dit, que les couches d’amygdaloides volcaniques de la montagne d’Akkrefell en Islande sont traversées par des veines de serpentine de plus d’un metre de puissance.*” Though I generally make it a rule to consult every-work I quote by name, which is accessible to me, I shall not in. this case be thought guilty of undue inattention, when, besides the accidental circumstance of being much hurried in the comple- tion of this paper, I made use of such high. antneniny as that of Brongniart. NOTE K. Vol. II. N. S. p. 346.—On the Mineral Waters of Ischia. The numbers which I have here given as a rude approxima- tion to the contents of the Gurgitello hot spring, and which were deduced from the description of Andria, seem to be either incorrect, or applicable to some other of the numerous. neigh- bouring springs; for in Dr Clark’s work on Climate,+ I find the following analysis by Lancelloti, professor of chemistry at Naples :— Contents of a pound. Spec. gr. 1.0065. Free carbonic acid, x ‘ 2.195 grains. Sulphate of soda, 3 fe 3.549 Sulphate of lime, “ ns 0.375 Muriate of soda, - < 15.425 Carbonate of soda, - “ 13.631 Carbonate of lime, magnesia, and iron, 0.500 | Silica, . - wa 0.375. 36.050 Analysis of the saline efflorescences on the walls of the Stufe, mentioned p. 346. By Dr farewecir . Anncith des Mines, 1821, p. 197, note. + Page 172. Notes. Q75 Sulphate of soda, - - - - » - 51.0 Muriate of soda, or - * “ 2.3 Carbonate of lime, - . - 4 at 5.2 Silica and other matter insoluble in water and in acids, 3.6 Water and loss, ss 4 - tee 37.9 100.0 NOTE L. Notice respecting the Climate of Naples. See this number, page 250. In promising a note on this subject, I merely proposed that it should contain a very few facts on this important, but little investigated subject. Where data are awanting, I shall not spend time by swelling this already too long paper by detail- ing the mere common places which supply their want. While the climate of Naples is a theme of general admiration, and its perfections have perhaps been exaggerated as a winter resi- dence, few have thought it worth while to analyze its qualities, — and Tenore, in his work on the Physical Geography of the King- dom, has been obliged to confess the meagreness of his ma- terials for the city itself, and their almost total want in the ex- tensive districts of Calabria, Abbruzzo, and La Puglia. The indefatigable Humboldt, in his work on Isothermal Lines, has been obliged to omit this important station in his list of as- certained mean temperatures; and the only good observations have been made since the time of the publication of that work, by Broschi, the astronomer-royal at Capo di Monte. His ob- servations have been reported and reduced by Tenore, and by Dr Clark, in his excellent meteorological tables appended to his work on Climate. As they are reduced to English measure we take them from the latter. The position of the point of observation close to the town of Naples is in north latitude 40°, 51’, 10”; longitude east of Paris in time 47’, 48’, and about 240 feet * above the sea. The period is from 1821-1825 ; and the hours of observation are sunrise and 2 p. m. which im this climate we should not consider very satisfactory for giving the mean temperature ; * Or 74 metres, as given by Tenore ; Dr Clark makes it 148 metres or exactly double. But I have selected the former as the most potehie in itself, and also the most likely to be correct. 276 Mr Forbes’s Physical Notices of the Bay of Naples. but as we find it 612.40, or almostywhat we should expect from the analogy of Rome, we may conceive that the accuracy con- sists ina compensation of errors ; the temperature at sunrise — being a little above the minimum; that at 2 p. m. a little below the maximum. In fact, by examining the admirable hourly observations conducted at Leith, we find the defect of ‘the mean annual temperature at sunrise below the mean = 3°.16; the excess at 2 rp. mM. = 8°.04, Ff Tabular View of the Climate of Naples. Year. Jan. Feb. Mar. April. May. June. Fay Aug. Sept. Oct. Nov. Mean temp|61.40 Maxima, Minima, Range,* 6.5 86 51 35 16.5 58 29 48.5. 60 31 71.0 88 56 32 75.0 93 4 29 me 72.5 88 60 51 28 42.0 |57.0 69 {78 38 43 Bl 35 93 29 64 He 29 Dec. Range of ) Bar. in Eng. in. f Rain in Eng.in.} No. of fine days. Cloudy, he 1.154 29.256 210 58 97 0.888 3.472 29 , a.sasjo.zas 1,221/4.631 13 17 | 0.710 2.315 17 6 6| 10 8 0.925 18 0.355] }. 7 6 2.126/0.61 4/0.748)2.146 0.266 7 44 1 6 oes age 16) 17 5 8 0.355)0.488/0.53210. 4.354): Rainy, ; * This range not being derived from register thermometers, comprehends only the limit of observations. + Mean height for the year 29.554 inches. + These numbers not being given by Dr Clark, are reduced from those in centi- metres recorded by Tenore. From the situation of the town and Bay of Naples, freely exposed to the sea on one side, with a hot sun directed upon a slope laid out to its meridian intensity, and on the other not distant from the lofty summits of the Apennines, ‘these spots are exposed to great and sudden changes of temperature, as the indication of ranges in the preceding table sufficiently shows. Hence also it is peculiarly at the mercy of the winds, each of which have their peculiar character. The north wind (Tramontana) is rather prevalent in winter, and is cool, as also the north east and east, (Greco and Levante,) which blow with considerable violence from the Apennine range. The south east, or Scirocco, is not unfrequent at all seasons; and in my opinion is, at least during winter and spring, not ies oppressive than that so much complained of at Rome, It blows sometimes even with violence, yet still preserves its de- pressing and unrefreshing character, high temperature, and ¥ Notes. 277 dampness: it is said sometimes to convey the sand of the African deserts to the shores of Italy. The Libeccio or south west wind, blowing the whole western mass of the Medi- terranean towards the mouth of the Bay, and coming in vio- lent squalls, raises in a few minutes the most violent tempests, the rapidity seeming the work of magic, and rendering the navigation of the Bay frequently dangerous, as those who have had any experience in its treacherous surface must be aware. Spring is the least defined of the Neapolitan seasons ; but this very fact is the principal boast of the climate, for of few others can it be correctly said. * Hic ver assiduum, atque alienis mensibus estas.” The mild winter, insufficient to stop the course of vegetable growth, rushes into the splendour of the Italian summer, In- tolerable as is the heat of the sun at the latter period, when unaccompained with fresh breezes, the mild winds of the west predominate so much, as to render the climate far from insup- portable, and on the coolest shores of the Bay, as at Ischia - and Sorrento, nothing but. delightful. At Naples itself the ordinary temperature of the height of summer is from 77° to 84°, hardly ever rising to the extremes given in the table, and never continuing at them. The winter is mild, but rainy, especially in November and December. I have given in this Journal for July 1828, a meteorological register for part of those months, showing the unsettled weather which characte- rizes them. After Christmas there is generally some cold weather, during which Vesuvius and the Apennines get a coating of snow, which, however, rarely falls, and hardly ever lies a day in the capital. The thermometer has been known to fall to 23° Fahr. , This sketch is all which space permits me at present to offer. For some account of the botanical geography of the kingdom of Naples, I may refer to the work of Tenore. The state of agriculture, the prolific nature of the Terra di Lavoro, the mode of growth of the palm, olive, and vine in this district, are subjects little attended to in this country, and would re- quire considerable eJucidation.* * Whilst this sheet is passing through the press, I have seen with great satisfaction Mr Lyell’s excellent work on Geology, and find with pleasure 278 Mr Potter's Experiments to determine the quantity : Art. [X.—An Account of Experiments to determine the _ quantity of Light reflected by Plane Metallic Specula un- der different Angles of Incidence. With a Description of _ the Photometer made use of- By R. Porter, Esq. Junior, Communicated by the Author. Havinc followed the grinding and polishing of lenses and spe- cula for many years as my favourite pursuit in leisure hours, by frequent practice in the operative part, and many experi- ments to improve the polishing powders, I began about eight- een months ago to attain some proficiency in this difficult art, and wished to know how near my specula approached to those of the late Sir William Herschel; who, in the Phil. Trans. for 1800, has given measurements of the quantities of light reflected by the plane specula which he used in his telescopes. These measurements he took on a plan similar to that of Bouguer, which he has described in his “ T'raité @Optique,” but this work I was not able to meet with, and not being then . aware that Priestley in his History of Vision has described the instruments used by him, I was left to make such modifications of Count Rumford’s plan of comparing the intensity of sha- dows as promised to make it serviceable in experiments where considerable exactness was required, and the speculum under examination but of small size. To avoid the stronger illu: mination which surrounded the shadows, and to find some de- scription of light or lamp which was not subject to sudden variation, were the most essential objects, and the various me- chanical contrivances detailed in the description, at the end of the paper, were adopted from time to time, as found necessary, to enable me to go through the measurements in less time and with more certainty. ‘The plan of this photometer I find is in principle the same as that of one of Bouguer’s; but, as given — by Priestley, his instrument was in a state much too incom- plete for inquiries similar to those which are the subject of the present paper; and there still remain sources of uncertainty ‘and inaccuracy which it is difficult to surmount. 'The one arises that he coincides in almost ail my views developed in these papers, as far as they were published before his work. His opinions on the Temple of Serapis in particular are strictly the same as my own, and I am glad to observe that he has corroborated them by some new analogies. ¥ of Light reflected by Plane Metallic Specula, &c. 279 from the fatigue of the eye experienced by looking long and intently at bright objects surrounded by darkness, which pre- vents it after some time judging accurately of very small dif- ferences, but this may in a great measure be surmounted by frequent practice. The variation in a few minutes of the quantity of light given out by every lamp, &c. which I have yet tried, is a still greater source of uncertainty, and to which, I believe, may be attributed most of the irregularity visible in the results about to be given. The principle of the measurements by the photometer is this, that the light incident on a given surface varies inversely as the square of its distance from the luminous object. Of the two lamps which are used, the one being for the purpose of comparison, remains stationary during the measurements, while the direct light of the other lamp, or the reflected light from the speculum, are made to give an equal illumination with it on the thin paper in the screen; and the quantity of light reflected is found by comparing the squares of the dis- tances which it has passed over to give the equal illuminations. In this way the direct light at 40 inches is equalled only ‘by the same light received through the medium of a plane re- flector of speculum metal when at 32 to 33 inches from the screen, or out of every 100 rays received by the reflector only about 64 to 69 arrive at the screen. A small oval speculum of about 1} inch in length, and 1 inch in breadth, and composed of about 143 parts of tin to 32 of copper, and highly polished, being tried in this manner, gave 65.53 rays of every 100, as reflected at 18° incidence, which is about 1.73 less than the average given by Sir Willian Herschel, who does not state the incidence at which he took them, but only that it was nearly perpendicular. It was the opinion of Sir Isaac Newton, (see his Letter in Phil. T'rans., dated Cambridge, May 4th, 1672,) that metallic specula, in common with all other substances, reflected light ‘* most co- piously, when incident most obliquely,” and this opinion has been adopted by every writer on the subject since. Priestley, after giving the results of some of Bouguer’s experiments with black marble and other substances, says, “ similar experiments made with metallic mirrors always gave differences much less considerable. ‘The greatest was hardly ever an eighth or ninth 280 Mr Potter's experiments to determine the quantity part of it, but they were always the same way,” that is, he found more light to be reflected by the mirrors which he used when incident obliquely than when incident perpendicularly. When I tried the above speculum with the angle of 45° . incidence, the average of 18 measurements, viz. 12 direct and 6 reflected, gave only 64.90, as the quantity reflected, showing a loss, instead of a gain, as the angle of incidence was increased ; but the apparent difference between 18°, the incidence at which the former were taken, and 45°, was so small.that I thought it possibly might arise from accidental inaccuracies; but another set. taken at 66° to 70° incidence, giving a still less quantity,’ I was convinced the fact was just the contrary to the general opinion in highly polished metallic surfaces. I knew this loss could not happen from the speculum not being truly plane, for, from the. way in which the polish had proceeded, it must, if any thing different from plane, be slightly concave, ‘These experiments involving a very important question not only im the science of optics, but also in the general relations of ponderable matter and light, I determined to bring the photometer into as convenient a form as possible, and to try them again with every precaution to insure as correct results as the nature of the subject would admit. Accordingly, on the 8th January last, having got a small oval speculum of the same size and composition as the one before-mentioned, to a very fine and high polish, and having used a new contrivance in the grinding and polishing, which made me certain that it was very nearly a true plane, I tried it in the photometer, aud found, as I had formerly done, that less light was reflect- ed as the angle of incidence was increased. Having in the meantime made some further alterations in the photometer on the 25th January, I obtained the following measurements : Angle , of tne oben Light direct. Light reflected. 20° Seach, 36$3+4+1$ =38%, equalled 275 +314 = 3123 in. 40°. 3 3875 +214 4019 291 +315 = 384, 60° 3 384 +3752 4235 2945+ 445 = A: : and 20° incidence (384% )* : (3193): : 100 : 69.45 rays renege 40° (40¢2)? ° (83,%)?: : 100 2 66.79 60° (4295)? +, (83}E)?: + 100, +, 64,91 of Light reflected by Plane Metallic Specula;&e' 281 _ I take the measurements alternately, first one of the direct, and then one of the reflected light, until I have a sufficient number of pretty uniform distances, rejecting them and com- mencing again when there has been any considerable variation in the lights. In this way the above did not vary more than } of an inch in. any two neighbouring trials of the same descrip= tion. : : | The following I obtained on the evening after. Angle of int ia Light direct. Light reflected. 10° Seach, 394 +2 =41} equalled 268 +74 = 34,4 in. 30° 3 - +133=3933 28454335 = 32,7% 50° 3 s.+3 aati 297'3+3i5 = 334 70° 3 +48, 4212 293 +5 = 3433 and 10° incidence (414 )?: (34/5 )? :: 100 : 68.61 rays reflected. 30° (3932)?: (32,4%)*: : 100: 66.58 ; 50° (414%)?: (333 )?::, 100 ; 65.42 70° (4942)?: (3443 )?:: 100 : 65.15 Three other trials taken at 10° incidence, but in which the lights had varied too much, gave 70.32 as reflected, and 3 in the same way at 70°, gave 65.91. Though the results of this set do not well agree with those of the former, yet there is clearly a convergency in the differences, which must be allow- ‘ed in spite of the uncertainty which attends this sort of experi- ments; where, if there were no other reason, the difficulty of the eye judging of such small differences would cause appa- rent irregularities. On the 27th January I obtained the fol- lowing: Angle aes a rer a Light direct. Light reflected. . 10° Seach, 38 +2 =40 equalled 254 +7,4 — 323 in. 30°. 3° ST Yg4+-1938=— 895% 28¥5+33$ = 31448 50° 3 873i +3rg=4 ge 29vet3iz = 33zy and . | 10° incidence (40 )?: (323 P:: 100 : 66.42 rays reflected. - 30° (3958)? : (31428)?: : 100 : 65.50 50° (4124)? 2 (33,4 )2:: 100 2 64.73 A set of 3 trials taken at '70°, which were very irregular, gave 282 Mr Potter's experiments to determine the quantity 62.92 aud 66.29 by different averages as reflected. In addi- tion to the convergency, it must be observed that the absolute quantity reflected is less in every succeeding set, which I attri- bute to cleaning, (perhaps too particularly,) the speculum, though only with soft leather every time before commencing, and I have before observed the same, that specula soon lose the highest reflective power which they had when just polished. This shows the necessity of having them recently and highly polished for this purpose; it appears also, and I have no doubt further experiments will confirm it, that the quantity at smaller incidences is more affected than at the greater ones, which I should have expected, for the scratches and other faults are always less visible when the speculum is viewed ob- liquely. The conclusions we are led to by the above experiments, are so contrary to the general opinion of philosophers, and to that of so many great authorities, that to be more certain of its being a general law in metals, I wished to compare also some other highly reflecting one, and accordingly, on the Ist and 2d February, reground and polished a small oval specu- lum of cast steel, and of the same dimensions as the former ones. On the 8th, I tried it in the photometer and obtained the following . Angl rf i PO Light direct. Light reflected. 10° Seach, 384342 =40}4 equalled 24334774 = 3153fin. 30°. 3 87 fo +1}38=3934 26234315 = 3084) 50° 5 38,5 +3ye=41 q5 | 26354352 = 30445 and 10° incidence (4034)? : (313,$)?: : 100 : 60.52 rays reflected. 30° (3948)? (30,88,)22 1 100 2 58.69 50° (41 %)? :. (30334)*: + 100 : 54.96 Those as well as another set taken on the 9th are more ir- regular than the former ones, with the mixed metal speculum, so also are the following taken on the 15th February. of Light reflected by Plane Metallic Specula, $c. 283 ot = pra Light direct. Light reflected. 10° Zeach, 374,42 =393, equalled 22} wha 298% in. 20° 8 8743411 =—3925, 25114314 — 9915 30° 3 38y5+1$3=4055 264 4315 = 2074 40° not taken 50° 3 87T§ +3 yo 4038 2533+313 = 2044 60° 3 38$;+375=4143 26444417 = 30233 and : 10° incidence (39345 )? : (2988 y?: 2 100 : 57.18 rays reflected. 20° (39.275)? : (2943 )?22 100 : 55.64 30° (40,), 2 (2924 yi: 100 ° 55.49 40° 50° (4048 2: (2944 )2:: 100 : 53.29 60° (4121 )2 : (30233)?: : 100 : 54.66 The irregularity observable in the above is no doubt owing to the badness of the measurements, and they show no reason for supposing that steel follows a different law to the mixed metal. | I have since thought that this badness arose from the fibres of the wicks being acted upon by the oil, and they had not been renewed. I was quite as careful in taking them as those of the mixed metal speculum. On the 22d February I com- menced a fresh set, but found the lights so bad, and the spe- culum evidently so much deteriorated, that, after trying to get better measurements for near two hours, I gave them up. An average of 14 of the best measurements, viz. 7 direct and 7 reflected, gave only 55.68, as reflected out of every 100 at 10° incidence, showing that steel, as well as speculum metal, soon loses its highest power of reflection, though it possesses so much more hardness and tenacity. Between the 15th and 22d February, it had only been twice in the telescope, and cleaned each time. As I had only ground and polished it in the common way for flat surfaces, I was not certain that it might be truly plane, and thought necessary to prove it on some astronomical objects. Accordingly, on the 19th February, with it and a 5} inch speculum of my own workmanship, of about 50 inches focal length, and with a power of 100, I saw _« Geminorum beautifully and distinctly defined ; and with a 284 Mr Potter’s Experiments to determine the quantity power of 150 saw y Leonis to be double at the first view, which I think will be allowed to be a sufficient test of its surfaee be- ing nearly plane. It has been generally and frequently asserted, that the quantity of light reflected by metals is directly as their den- sity, but this view is clearly untenable ; for, though the quan- tities reflected by steel and speculum metal are nearly in the ratio of their densities, yet, if we pursue this rule, and apply it to gold and platinum, whose specific gravities are about three times that of steel, we shall find that they ought to reflect much more light than they receive, which is absurd. But I find that the quantities of light which are absorbed or lost in the » two metals which were the subjects of the foregoing experi- ments, when the rays are incident nearly perpendicularly, are almost exactly in the ratio of their specific heats, taken for equal bulks. It is a highly interesting inquiry to learn whether this will hold as a law with the other metals. At present we know so little respecting the forces concerned in producing the pheno- mena of reflection, that every theory must be mere hypothesis which would show why highly polished metals should reflect most light when incident perpendicularly, and what should be the law when incident obliquely. Description of the Photometer. -The photometer consists of an upright screen a 6, Figs. 6 and ‘7, about forty inches in height, from about the middle height of which projects the lateral piece bc, Fig. 6, or be f, Fig. 8; which is about four and a-half inches broad and fifty inches in length, and supported near the farther end by a leg as at g. In the middle breadth of this lateral piece is fixed an upright pasteboard, 6 d e, Fig. 6 and 7, of four inches in height, and in length the same as the lateral piece. The two lamps are on the lateral piece, one on each side of the pasteboard, which keeps separate the light from each lamp. 'There‘is an aperture cut in the screen, as at b, Fig. '7, four inches broad and two and a-half ‘inches high, which is covered over with thin paper, and when the lamps are lighted, each half of this paper is illuminated by its own lamp, and the shadow of the thickness of the paste- | 4 7 ue ) UF of Light reflected by Plane Metallic Specula, $¢. 285 board appears like a dark line between them, as at 6, Fig. 2. When the illumination is not nearly equal from each lamp, the _ difference is seen very distinctly and beautifully upon this thin paper when viewed from behind the screen. To avoid the necessity of going frequently into the stronger light, which prevents the eye for some time after from judging of small differences, and to enable me to go through the expe- riments with more speed and certainty, I placed the lamps on ‘slides made of thin slips of wood, with thicker pieces at their farther extremities. 'The ends of the slides are seen on each side of b, Fig. 8, so that while observing the illumination of the paper behind the screen, I could draw the lamps nearer to, or push them farther from it; and having the right hand slide marked with inches and one-fourth inches to the commence- ment of the thicker piece of wood at its farther extremity, on which the lamp was placed, and to which the part carrying the reflector was attached, I could read off this distance also with- out leaving my seat behind the screen, by using a dark lantern. Fig. 9 is a larger plan of the piece of wood at the extre- mity of the right hand slide, showing how the different angles of incidence are obtained by placing the lamps at pins fixed in the wood for that purpose, which give the required angle at once when the flame is seen in the centre of the speculum through a small hole bored in the screen for that purpose, just above the centre of that half of the thin paper, the speculum being fixed to an arm, which turns round the pivot fas a cen- tre, being at the angle 45°, as used in the telescope for conve- nience. For a shade to intercept alternately the direct and reflected light, I have a square piece of wood which turns on a pivot at 4, and into it are fixed two upright pieces a b, be, at right angles to each other, and to the square piece. When a bis in the direction of the screen, the reflected light is inter- cepted; and when 6 ¢ is in that direction, the direct light is intercepted ; and I can turn it in either direction by pulling one or other of the strings which are fixed to its opposite cor- ners, and brought to the screen so as to be nearly tight when the lamp is at the utmost distance required, see h, Fig. 8. The upright pasteboard must be well blacked on the left hand side, and the right hand. side covered with black velvet, to prevent all interference of foreign light, and so also must 286 Mr Potter's Experiments to determine the quantity the shade which intercepts the light, and all the parts about the right hand lamp must be well blacked, as well as one-third of the length of the slide; and if any other precautions are necessary, they will soon suggest themselves to any one who is desirous to have correct results. I have found the variation of the light of the lamps much diminished by using four small wicks, as shown in the figure, with a larger hole in their centre to admit air to the inside of the flame. Perhaps if more and smaller wicks still were used it would be better. The wicks should not be used if they have been more than a day or two in the oil. I believe now _ that the irregularity of the measurements taken with the steel mirror, is entirely owing to the wicks having remained so long as to be acted upon by the oil. The flame must not be larger in proportion to the apclalaie than so that the latter may reflect the light from every part to the screen when they are most distant from each other. I found some difficulty at first in judging of the equality of the illuminations when T used a speculum of the common metal, from its giving the light a yellow tinge: but by tinge- .ing the light of the other lamp to an intermediate shade, by a small piece of pasteboard stuck behind it, and painted of requisite colour, the difficulty is done away with. The best sort of paper I have’ found to receive the light upon in the screen is the thin unsized paper which is used to take copies of letters under the press, and it must be stretched tight over the aperture by moistening before pasting it to. It will be seen that the divisions commencing only at the thicker piece of wood, the distance of the lamp in the direct measurements, and the sum of the distances of the lamp to the mirror, and the mirror to the commencement of. the divi- sions, must be added afterwards in the reflected ones. On the law by which the reflective power varies at different incidences in polished metallic surfaces. The quantities of light reflected by metals, as we see by the experiments, have a particular relation to each other, the diffe- rences evidently converging for equal differences in the angles of incidence as we increase those angles. of Light reflected by Plane Metallic Specula, &c. 287 If we form a geometrical construction, like the accompany- ing one, Fig. 10, taking the point O in the line P Q for acentre, and describe the circular arc R Q a quadrant, with radius O R or OQ = 100, and if we divide this quadrant into ares of 10° each, and draw radii O 10°, 0 20°, O 30°, &c. to these points in the circumference, we may consider the light to be incident at O at these angles; perpendiculars being let fall upon the radius OQ, the distances O s 10°, O s 20°, O s 30° &e. will be the sines of incidence to radids 100. If now on the perpendiculars, produced if necessary, we set off the quantities of light reflected at the various incidences in the measurements for speculum metal taken 25th January, we find these terminate at a 6b c, and these points are almost exactly in a right line. To subject this to calculation, and prove how near it agrees im numbers with those of the experiments, we must take the analytical expression for a right line, y= aa+0, then the lines O R, O Q will be the axes of the co-ordinates ; the values of y will be the proportion of light reflected, radius being taken as the quantity supposed to be incident, and # will be the sine of incidence to that radius; 8 will equal the quantity reflected when incident perpendicularly, a being the trigono- metrical tangent which a parallel to this line drawn through the point O makes with the axis of z. In the experiments of the 25th January, b is about 72.3, and a is trig. tang. of about 355° 12’. From these data we find :— y at O° incidence = 72.3. y at 50° incidence — 65.87 10° = 70.85 60 = 65.03 20° - = 69.43 70 - = 64.41 30° = 68.11 80 = 64.04 40° = 66.91 90 = 63.91 which we see is as near to the quantity determined by experi- ments as can be expected from the nature of them. It is also remarkable, that, in the experiments of the 26th and 27th, the quantities still form right_lines, though the re- flective power was diminished ; the last measurements in those of the 26th and the first in those of the 27th, being the only 288 Professor Berzelius on the ones showing anything of irregularity, and this not more than must be allowed for error in photofhetrical investigations. Hence I deduce this law, that the reflective power in metals of smooth surface is a function of the sine of incidence eon: taining two constant quantities, which have different values for different metals, depending on the peculiar nature of each. — We are at present ignorant of the properties which produce the: forces, whose effects are represented by @ and 8 in the above formula, and even whethef they have any dependence on each other; but we may conclude, from the simplicity of the law, that the case of reflection by metals is of the simplest order. ; “Ss ] 4 uA‘? Art. X.—On the Double Chlorides of Gold and. Potassium, with a Note on the Tartarie Acid of the Vosges. ears Pro- fessor Brrze.ius, in a Letter to the Epiror. Six, Iw the 5th Number of the Edinburgh Journal of Science, which I have just received, I find in page 138 the result of an analysis of the.double chloride of gold and potassium, which I had the honour of making conjointly with your countryman Mr Johnston, which differs essentially from the result of an analysis made by Mr Johnston after his return to Edinburgh, and from which he concludes that there may exist. two diffe- rent double chlorides of gold and potassium. I consider i it my duty to explain this point. Mr Johnston having inform. ed me some time ago of his suspicions as to this matter, I have examined the data obtained ‘by the analysis he describes, and I have found, that, by an error of subtraction, the weight of the chlorine was diminished by a quantity, which, by the same error, was added to the chloride of potassium. The weight of the gold is what it ought to be in the anhydrous salt. T have since made a new analysis of the same double salt, of which I take the liberty of communicating to you the result. Chloride of potassium, 17.525 ] atom. 5 Metallic gold, - 46.800 = 1 ——.» »)) Chlorine, - - § 26.050 =3— Water, - - 10.625 = 5 ——. double Chlorides of Gold and Potassium, &e. 289 This analysis differs a little from that of Mr Johnston, in as- signing to this salt an atom more of water, Mr Johnstom having found only four. I would not dare to insist on the preference of my result, for this salt is very efflorescent, so that im endea- vouring to dry it perfectly, that it may contain no uncombined moisture, we risk a partial efflorescence ; while on the other hand, in avoiding efflorescence, we are never sure of having it perfectly dry. ° To ascertain if there be another double chloride of gold and potassium, I have made different experiments, which seem to prove, that the chloride, proportional to the per-oxide, combines in only one proportion with the chloride of potassium, but that there is also a double chloride in which the chloride of potassium is combined with the chloride of gold, proportional to the protoxide of gold, (the protochloride). It is formed by melting the preceding. The melted mass is brown and pellucid at the edges, resists for a long time a bright red heat in close vessels, and leaves much metallic gold undissolved when treated with water or muriatic acid. If you think this explanation of the results communicated in your Journal by Mr Johnston will interest your readers, I beg you to do me the honour of inserting them.—Accept, Sir, the expression of my very high regard, : Jac. BERZELIUS. Postscript.—I have newly finished a research which has given me some very curious results. _I wished to examine the difference between the analytical results obtained from tartaric acid by Dr Prout and myself,* and at the same time I have analyzed an acid found in some kinds of tartar, and examined by John, Gay Lussac, and others, who have all determined positively that it differs from the tartaric acid. In the analy- sis I have made of it, I found that it has the same composi- tion and the same atomic weight as the tartaric acid, from which it differs precisely as the pyro-phosphoric does from: the phosphoric, or the cyanous from the fulminic acid. The ex- * This difference amounted to one volume, or half an atom of hydro- gen ; and Berzelius’s new result, as expressed in a letter to Mr Johnston, agrees entirely with the accurate result of Dr Prout. NEW SERIES. VOL. III. NO. Il. OCTOBER 1830. T ' 290 Mr Johnston on the double Chlorides of Gold amination which I have made of these bodies having an iden- tical composition, but. possessing different properties, leads to a research entirely new to that of heteromorphous bodies com- posed of the same number of atoms of the same elements, but combined among themselves in a different manner, just as the experiments of Mitscherlich have discovered isomorphous bo- dies composed of the same number of atoms of di alle ele- ments,—but combined in an andlogous manner. 1931 eg SrockHoim, 12th July 1830. Arr, XI.—On the double Chlorides of Gold with Potassium and Lithium. By Jamus F. W. Jounston, A. M. Com- municated by the Author. . I. Potassium Salt. Iw a paper on the double Chlorides of Gold, published in the preceding number of this Jowrnal, I inserted an analysis of the potassium salt I made in Berzelius’ Laboratory with great care, but differing very materially in its results from a suc- ceeding analysis performed by myself. Before publishing either analysis, I communicated my results to Berzelius, and should have waited his reply, had he not informed me pre- viously that he had already made known his results to the Swedish Academy. Soon after my paper was published, however, I received a letter from Berzelius, informing me that my analysis was substantially correct,—that he had veri- fied it by a new analysis of his own, and had found, on look- ing back to his note-book, ‘an error of subtraction, by which the calculated result of his former analysis had been vitiated. 'Phis new analysis and correction I had intended, in justice to Berzelius, to make known in this Journal, but the reader will find the whole matter explained in the letter forming the pre- ceding article, which Dr’ Brewster was kind spe i to traitis- mit to me. The new result of wersdtivs differs from mine only r as- signing about 1} per cent. more water to the constitution of the salt.. My hh gives 9.13, and that of Berzelius 10.62 for the per centage of water; he therefore deduces five atoms for that contained in each atom’ of the salt. ‘On learning: his with Potassium and Lithium. 291 result, I felt that I could not insist upon this point, and for the reason he has stated, though, éxcept when in very thin scales, I have not found the crystals effloresce so very speedily as they seem to have done in his probably drier laboratory at Stockholm. I have, however, made two other experiments, with the view of determining the point. 24.76 grs. of the crystals, partly prisms, and partly large plates, after drying on bibulous paper, and before the slightest trace of efflorescence had shown itself, were heated on a water bath for an hour, when the loss amounted to little more than eight per cent. Heated more strongly to incipient fusion, the loss amounted to 9.26 per cent. By a third heating the ulti- mate loss was 2.3 grs. = 9.4 per cent. One portion of the salt in this state being fused in a tube over a spirit lamp gave still a trace of moisture; while another portion treated with water, left a small insoluble residue of proto-chloride of gold. From this experiment we should infer that 9.4 was very near the true per centage of water in the salt. Again, 20.21 grs. in fine prismatic needles were dried by pressure between folds of paper, and when they had the ap- pearance of being dry, were taken from the still. moist paper and weighed. By drying at 212°, they lost only 8.4 per cent. but by heating more strongly till an odour of chlorine became perceptible, the loss reached 1.91 grs. = 9.45 per cent. In this state they stiil dissolved in water without the slightest re- sidue, and gave a trace of moisture when fused in a tube. This experiment would lead us to suppose that the true amount of water exceeded 9.45 per cent. In the state of pris- matic needles, however, the salt is not so well adapted for ex- periment as in that of large crystals, and I have reason to think, that. the erystals employed in both these experiments still retained a portion of moisture mechanically attached. As- suming, therefore, 9.45 per cent. for the quantity of water contained by the crystals; a quantity exceeding my former de- termination by .32 grs. the several analysis of this salt hither- to published will stand as follows: | 292 Mr Johnston on the double Chlorides of Gold. » J&val. Berzelius. Johnstons Chloride of potassium, 1 atom, 2426 17.525 18.38. Chlorine, 3 68.64 25.050. 25.440. Gold, . ] 46.800 46.73. Water, | 4 or 5 atoms, 7.10 _ 10.625 945 - 100. 100, 100 There is a curious property of many salts which I have seldom seen adverted to, but which is nevertheless extremely deserving of attention. We commonly describe’ salts in their crystalline state only, and attend little to their habits in the amorphous state. And yet, in this state, they oceasionally exhibit very interesting phenomena. Some salts, when de~ prived of their water by fusion, deliquesce on cooling, and run into a liquid in which crystals are afterwards gradually deposited till the whole has assumed the form of a erystalline salt, containing water, and permanent in the air. Others at- tract only so much moisture as to admit of an internal motion of the atums, and assume a crystalline arrangement without becoming liquid, of which kind is common barley sugar, as: has been shown by Mr Graham. The chloride of gold and potassium is an efflorescent salt, and when left to itself gra- dually falls to powder. Yet the large crystals employed in the former of the two experiments above detailed, after heating to the fusing point, and losing by that means upwards of nine per cent., being set aside for a couple of days, had reached at the end of that time within half a per cent. of their original weight. Such an attraction for moisture we are not prepared to expect in an efflorescent salt, but all these phenomena are’ probably due toa tendency, with which I consider all matter to be en- _ dowed, to assume regularly crystallized forms, and to attract to themselves such neighbouring substances as may aid that tendency. This proneness to crystalline arrangement, how- ever, is not to be recognized as any new principle, but —, as an uniform result of universal mechanical laws. II. Lithium Chloride of Gold. When I drew up my former paper I had not formed this salt. I have since prepared a small quantity of it, and am with Potassium and Lithium. 293 enabled to describe its external characters. I had in my pos- session a quantity of sulphate of lithia, prepared by Arfved- son, from which I formed a quantity of chloride, by means of barytes. This was mixed with chloride of gold, and the li- quor carefully evaporated. Crystals of the potassium salt first separated, easily recognized by their appearance, and by their efflorescing property, showing that the sulphate of lithia had not been purified from potash. After two or three careful~ evaporations these ceased to be separated, and a crop of mi- nute prismatic golden-yellow needles was obtained, capable of removal, but not of drying between folds of paper, owing to their rapid deliquescence. In the air they speedily dissolve into a yellow liquid. At 212 it becomes opaque and parts with its water, and by the flame of a spirit lamp is wholly de- composed, giving off chlorine, aud leaving metallic gold with the deliquescent chloride of lithium. Were the preparation of this salt not too expensive a process, it might be recom- mended as a very effectual one for separating the two alkalies, potash and.lithia; experiment, however, may probably imdi- cate other triple salts by the different solubilities of which the same object may be satisfactorily accomplished. I have not made any analysis of the lithium salt, as I con- sider the analyses already given of the other salts sufficient to establish the theoretical composition of all these combina- tions. The water of crystallization alone is wanting, and that the avidity of this compound for atmospheric moisture prevented me from attempting to ascertain. I shall subjoin here a view of the distinctive characters of the four salts of gold with the alkalies. 1. The sodiwm salt is permanent in the air.. The potas- ‘sium and ammonium salts efflorescent, and the ithiwm salt ra- pidly deliquescent. 2. The sodium salt requires a strong heat aiid: length of time to dissipate its water of crystallization. The potassium - salt parts with all its water at a heat a little above,—the am- monium salt something below, and the lethiwm salt about that of boiling water. 3. The poassiwm and ammonium salts are easily distin- guished by the readier efflorescence of the latter, and by its 294 Dr Hibbert on the Ancient form of giving off at a gentle heat not only “chlorine, but white fumes of sal-ammoniac. 4, All the salts crystallize in four-sided prismatic Been but in- this state the sodiwm salt is readily recognized by its péculiar aspect, giving an impression as if the crystals were all longitudinally striated. In larger crystals it is denser than the other compounds, and darker coloured; emitting a dis- tinct metallic sound when dropped upon glass. sod tei 5. Left to spontaneous evaporation the predominating form of the sodium salt seems to be flat rhombic prisms, or large re- gular rhombic tables forming flatly on the bottom: of. the ves- sel. Of the potassium salt, rhombic prisms, and) from a ‘solu- tion containing excess of potash, large beautiful pale yellow prisms supported edge-ways, and increasing upwards into the fluid. The ammonium salt undergoes more modifications, It forms large rhombic tables or thin plates, increasing upwards after the manner of the potassium salt, or four-sided, modified at the edges into six-sided rectangular prisms.’ ‘The lithium salt in prismatic needles has something of the aspect of the so- dium salt in the same form; but it soon) loses this — 7 its rapid deliquescence. Dr Brewster informs me that all these salts possess the re- markable property of dichroism ; and gives me reason to hope that he will examine their crystallographic and poste charac- ters more nearly as soon as leisure hee : ‘pth PortosEeLLo, 24d August 1830. im Anr, XI.—The most ancient form in:which Gold tous made use of in Scotland as the current money of the times. Com- municated by S. Hrszrert, M. D. F. R.S.E. &e.. ineate four or five weiitn ago the hows notice appeared in the Inverness Courier :— i ‘In ploughing up a field at Leys; near the town, the ploughman found a rod of pure gold, about fifteen inches long, with three sides, each about half an inch in depth. In the middle it is twisted, and terminated by a bend similar. toa Gold Moncey in Scotland. 295 shepherd’s crook, in very rude workmanship. | It was purchas- ed at L.4, 10s. by Mr Naughton, jeweller here, and is now in: his possession. No one who has seen it can imagine the ‘use to which it may be applied; but we hope that the owner of it will not send it to the crucible till it is examined by some of our antiquarians.” After this notice had appeared, Sir Henry Jardine kindly submitted the rod to the inspection of the Society of Scottish Antiquaries at one of their meetings, in which I was present as Secretary; and on the same occasion was read a short notice of it by Mr George Anderson, F.R.S.E., the active and. able Secretary of the Northern Institution of Inverness. “ The only additional information I have been able to pro- cure,” says Mr Anderson, ‘ respecting this discovery i is, that the plough seems to have gone several times over. \the spot where the treasure lay before it. was noticed, and that the bend in the largest portion of the rod is thought by some who have seen it to have been occasioned either by the horses’ feet or by the ploughshare.” It was also added, that ‘* two or three small pieces subsequently found, were also brought to the jeweller, forming, when joined together, a gold rod of about 18 inches in length, nearly half an inch in thickness, three-sided. or grooved, and spirally twisted.” The information thus conveyed, in connection with the ac- tual relic which was exhibited, showed that it was nothing but a plain spiral gold rod, perhaps eee unbent, devoid of all ornament whatever. » Regarding its probable use, much was oda on this occasion. Mr Anderson communicated the opinion of a learned gentle- man, the author of the Culloden papers, who imagined that — all the pieces found must have formed portions of a bent wire or rod for suspending the sacrificial vessels of the Druids. Another opinion hazarded by Mr Anderson, though with proper diffidence, and in which I myself was disposed to con- cur for want of a better conjecture, was, that the gold rod might have been an ensign of office, or some mark of distinc- tion worn by a chief for superior wisdom or valour, analogous to the golden torquis or collar worn by chiefs of many ancient 296 Dr Hibbert on the ancient form of Gold Money, &c. nations, or to the wreath of gold (térch aur) said to have been particularly im use among Welsh leaders of distinction. «« |) The discouragement, however, to this last supposition, was, thattherewas.a great presumption that the gold relic never exists ed in the formof a collar, and that, being devoid of all ornament, and in the simple form of a spiral sari it could not possibly have been devoted to this purpose.. Nor was the probability more in favour of the first. mentioned opinion which assigned its use to the Druids; proofs being equally wanting that the — Druids ever made a sacrificial use of rods of this kind, or that this order of Celtic priesthood had ever found a way to the distant lands of Inverness. In short, the antiquities of this vicinity, too confidently imagined to be Druidic, are rather assignable to the Scandinavians, who formed a settlement om this coast. gh} But it is now time to advance my own theory, dobiehi Is simply this: That the said rod of gold, found near Inverness, indicated nothing more than the form of the current money of many northern countries, when paid in gold... Thus we find that in the Welsh laws of Howel Dha, it was enacted, that for invading the prince’s bed the offender was ‘‘ to pay a rod of pure gold of the thickness of the finger of a ploughman, and in length from the ground to the prince's mouth when sitting.” And in another part of the said code, it is enjoined, that the fine for insulting the king of Aberfraw shall be paid as fol- lows: a hundred cows from every hundred in his lordship ; a rod of gold as long: as himself and as thick as his little fin- ger: and a dish of gold as broad as his face, and as thick as a eget s nail, who has been a husbandman for seven _ years.” ree From these quotations the use and nature of the unorna- mented spiral rod of gold, found at Inverness, is so self-evi- dent, as scarcely to need a single comment. But 1f any suspi- cion should exist that it was still more intended for ornament than as a species of currency, I am fortunately enabled to quote an extract from the Rev. James Johnstone’s translation of the Norwegian account of Haco’s expedition against Scot- land, A. D. 1263, to show, that while a valuable rod of this kind was converted by the same Northmen, who peopled many Mr Powell on the alleged. Polarization of Heat. 297 parts of North Britain, to the purpose of money, it was acknow- ledged to convey a twofold signification, being, from its flexibili- ty, and syperior worth as a metal, rendered a badge of power. A rod of gold which could be thus twisted was named a ring, and Johnstone states in a note, that Riga (the word quoted in. an ancient Saga) “ not only signified rings or bracelets, but also money; for before the introduction of coimage into the north, very thick spiral gold wires were worn round the wrists of great men, who distributed dits to those who performed any signal service; and such a wire 1s still to be seen in the Royal Museum of Copenhagen. It is not always easy to discern when by ringa is understood ornaments for the fingers, bracelets, rings of investiture, or the current money of the times.” The use of the spiral rod of gold found near Laverness, the ancient resort of the Vikingr, is at length rendered manifest. It was the current money of Scotland, which the chief was wont ~ to distribute in bits to his followers, and when twisted mani- - fold around his wrist, served as a badge of opulence and dis- tinction. ‘This is perhaps one of the most curious antiquari- an relics which has been found in Scotland for many years. I am ignorant of its fate, whether it has met with preservation in the Museum of the Northern Institution of Inverness, or has been committed to the crucible. I regret at the time I saw it my ignorance of its use, and of the interest which it was thereby calculated to excite, as showing the most ancient form in which gold was made use of in Scotland, as the most valu- able of currencies. Art. XIII.—Hemarkson the alleged Polarization of Heat. By the Rev. Bapen Powen1, M. A. F. R. S., of Oriel College, Savilian Professor of Geometry in the University of Oxford, _ and Honorary Member of the Society of Arts for Scotland. Communicated by the Author. Tw analogies between light and radiant heat have formed a fa- vourite topic of inquiry and discussion to natural philosophers : and have certainly in several instances afforded the means of a, 298 Mr Powell on the alleged Polarization of Heat. guiding them to the discovery of important properties of heat. At the sathe time it must be admitted, that the points of ana- logy have in many cases been mistaken, and hence much vague and hypothetical speculation has arisen. \ Nota little perhaps of such speculation has been occasioned by the confused ideas long adopted as to the nature of the heating agents described _ under the general name of “‘ radiant heat,” but which I con- ~ ceive later experiments have tended to dispel, by analyzing the effect so designated into its component elements, and thus fur- nishing us with more precise notions, by the adoption of which we may view the various results already obtained in a new and clearer light, perceive their relations and analogies: present- ed in a more just point of view, and thus possess’ a more sure foundation for further researches. soem The discovery of the polarization of light by defensin and the law of its subsequent non-reflexion at the proper incidence when the planes of reflexion are at right angles, exhibited by the experiments of Malus, afforded a new field of inquiry to those who were engaged in pursuing the analogies of light and heat. Accordingly, the subject was taken up by M. Berard; with the view of trying whether a similar property was: pos- sessed by ‘ radiant heat,” using the term in the eagpeminen vague sense in which it was then employed. ding It is to be regretted that of his experiments we possess: ca further accounts than very general abstracts. Berard’s me- moir was read before the French Institute, and in the Annales de Chimie for March 1813, is given the report of ‘the oes missioners of the Institute upon it, of which a translation < pears in the Annals of Philosophy, O.S. vol. ii. p. 164. Thesub- stance of the same statement is also given by Biot in his T’raité de Physique, vol. iv. p. 602. Tn this report the Commissioners recommend the memoir to be printed in the ‘ Recueil des Savans Etrangers,” but, as far as T have been able tolearn, it - has never yet been printed. The title of the memoir is, “ On the Physical and Chemical Properties of Solar Light.” In the sequel, the author is led to examine the polarization he considers it) of the solar heat ‘by reflexion, as in Malus’s apparatus, collecting the rays reflected from the second | by a concave mirror having re blackened thermometer i tie vw Bate Mr Powell on the alleged Potarization of Heat. 299 focus, adjusted so as to receive the rays at the proper angle, and fixed so as to move round in azimuth with the second glass, and ‘to continue in an invariable relative position to it. With the same apparatus he is stated to have tried the effect, when, instead of the solarrays, was substituted the radiant heat’ from a mass of hot metal, ** 2 peine rouge, ou méme tout a fait obscur,” (Biot, iv. 611.) In both cases the result was, that in the same positions in which light was reflected or not from the second glass, the heat was likewise reflected or not. Upon finding the distinction between the two species of heating agents, which I conceive is established in my paper, (Phil. Trans. 1825, Part i.) * I was naturally led to examine the above statements respecting polarization in connection with that distinction. So far as respects the solar rays, it having been, as I con- ceive, clearly established that the solar heat is of one simple kind, viz. of the species distinguished by passing through transparent media without heating them, separable from the rays of light, and only developed upon the absorption of those rays by black surfaces, Berard’s results appeared to me to amount to this, viz. that the solar light when polarized still retains its heating: power unaltered ; and, accordingly, whether the light is reflected or transmitted by the second glass, ac- cording to its azimuth, the heating power 1s of course conveyed with it as in all other cases. A contrary result would have been an extraordinary exception to the general law. In regard to the effects derived from hot metal, I could wish the results had been stated ina more specific and detailed form. If they be understood as applying to the case of hot metal possessing any degree of luminosity, it is certainly conceivable that the portion of the effect due to the light may have been sufficient to exhibit a minute effect precisely analogous to the case of the solar light: with regard to metal absolutely non-lu- minous, and to the other portion of the effect, viz. ihe simple heat in the case of duminous hot metal, the main question would arise. ‘I'o show that simple heat, distinct from light, exhibits this modification would be a point of the highest interest : and this Berard is stated to have done. Supposing the fact to be as recorded, we must carefully observe how far the ana- * See Note at the end. 300 = -Mr Powell om the alleged Polarization of Heat. logy extends, and this is merely"to the circumstance of non- reflexion in the proper azimuth. There is nothing to show whether the heat which was not reflected was transmitted like light, (which would be a remarkable exception to the general law,) or whether it was absorbed by the glass, which would render the phenomenon essentially different from pee ssc tion of light. The great importance of Berard’s result, as as “to simple heat, makes it a matter of extreme regret that we should. have no further account of it than so very general a statement as that just cited. It since became a point of the greatest in- — terest to me to endeavour to verify such results—to examine closely into all possible sources of deception,—and to attempt to remove any uncertainty or ambiguity which might be sup- posed to affect the question from want of due distinction be- tween the different species of heating agents. Immediately on the termination of my former inquiries, therefore, I commenced a set of experiments on these points ; but the great difficulties I found in carrying them on, or, to speak more precisely, in obtaining any results at all, together with other causes, have delayed and protracted the prosecution of the inquiry till.a very recent period, and even now the results are far from be- ing as satisfactory as I could wish. I will proceed, however, to a brief account of my attempts, from which a tolerable judg- ment may be formed how far I may be considered to have substantiated my conclusion, which goes to contradict that of Berard so far as simple heat is concerned. I am fully aware of the difficulty of proving a negative, and especially when in opposition to such high authority; but in the absence of any detailed account of his experiments, my attempts may not mm haps appear wholly devoid of interest. r The apparatus employed for these experiments, was spesillly similar in principle to that used by Berard. It consisted ofa _ tube having at each end a plane reflector of plate glass inclin- ed to the axis at about an angle of 353°, and capable of ad- justment by a screw; the tube consisted of two parts sliding one in the other, so as to give to the second glass a motion in azimuth. To the frame bearing this second glass..was fixed an arm carrying a small concave metallic reflector, and a side Mr Powell on the alleged Polarization of Heat. 301 branch holding a small mercurial thermometer, which could be adjusted so that its bulb should be exactly in the focus of the reflector; and this reflector fixed in the requisite position to receive the rays from the glass reflector at the polarizing angle. - When the apparatus was in use, therefore, a source of ra- diant heat being placed in a proper position with respect to the first glass, the rays of heat would be reflected along the axis of the tube, and impinging on the second glass would be again reflected from it; and being intercepted by the concave reflector, would be made to converge at its focus, and thus concentrated, would fall on the bulb of the thermometer. The apparatus having been adjusted for light, the observations were to be made for heat in the first instance, with the two glasses in the same azimuth, that is, with the planes of both the first and second reflection comcident. The second glass was then to be turned round in azimuth, through a quadrant ; so that the two planes of reflexion should now be at right an- gles. If then the heat had acquired by its first reflection a property of polarization analogous to that which light requires under the same circumstances, we ought in the first position of the second glass, that is, in azimuth 0°, to perceive an effect on the thermometer, and at azimuth 90°, to observe none, or a gently diminished effect. In applying these considerations to practice, however, there are a multitude of circumstances to be attended to, which materially interfere with the results. Into the detail of these circumstances I shall not attempt here to enter. It will in general be sufficiently evident that among the first objects of attention must be the exclusion of irregular radiations, cur- rents of heated air, &c. This can never perhaps be perfectly effected. The reflectors become heated ; the different posi- tions of the second glass in azimuth may place it and the ther- mometer in a different situation with respect to some or other of the heating causes. I have in many preliminary trials been greatly misled by effects due to circumstances of this kind. But itis impossible to detail them in a paper like the present ; and the general statement must suffice to assure the reader, that no caution was spared in guarding against these fallacies, 302 Mr Powell on the alleged Polarization of Heat.) and to warn those who may repeat the experiments against their influence. The main difficulty with which I had:to eon: tend in these experiments is the very small total amount of the — heat which in any case arrives at the focal thermometer. \'This small effect, even in the most favourable instances, was unavoid= ably more or less disguised by interfering causes ; and the dif_i- culty of appreciating the difference, if any, due to a change of azimuth, was such as to render the most numerous re necessary before any degree of confidence could be placed'in'the — results indicated. The thermometer was a very delicate one con= structed on purpose: its scale was such as to admit of a centis grade degree being divided into 5ths, and the 10ths are readily duchitinned: The bulb is about one-fourth inch diameter: detached about one inch from the mounting, and coated with Indian ink: My object was to try experiments on the principle thus de- scribed in the case of simple radiant heat from non-luminous sources, as well as in that of the compound radiation from lumi- nous'hot bodies. Jn this latter case the one species of heat could be separated from the other by the interposition of a glass screen, (which was usually placed about half way in the tube,) and the modifications which each portion might — iow be separately discovered. The direct experiment was to be made (as I Ronen allel described) by means of the heat reflected from the second glass : but comparative experiments might also be made on the heat transmitted through the second glass, if any ; and this, in the position of non-reflexion, ought, if the analogy with light hold good, to be displayed in a maximum effect on the thermometer in that azimuth, if the concave reflector with the thermometer in its focus were placed behind the second glass ; and inseveral series of experiments this arrangement, which may be ‘called complementary to the former, was adopted. \ And this point was further pursued by observing the temperature acquired by - the second glass, by means of a small thermometer in contact with it, in order to find whether it absorbed without transmit- ting more heat in one azimuth than in the other. ¥ aera The experiments were tried upon the radiations from ‘the flame of an argand lamp, and from ‘a ball of iron heated to the brightest incandescence which a common fire'could pro- ORS TS ee rs Mr Powell on the alleged Polarization of Heat. 308 duce, as well as at a point below visible redness. The total effects, as I have already observed, were in all cases but very minute. This was, indeed, to be expected ; nor, upon a care- ful consideration of all the circumstances, did it appear prac- ticable to obtain larger indications which would not be affected by proportionally increased causes of error. The simple radi- ant heat from the red hot ball after two reflexions becomes al- most insensible, while the glass reflectors, especially the first, become heated, and the radiation from them disguises the result. ‘The same may be said of the entire radiation from hot iron when non-luminous. The other part of the heat, viz. that belonging to the light, is excessively minute, but is less liable to be lost in reflexion. In the case of flame, this part of the effect would constitute nearly the whole after-re- flexion, since the simple heat would hardly be ‘senietb ts even after one reflexion. Under these circumstances, after very numerous repetitions in each case, I was hardly surprised to find that, even in re- gard to the light, the most minute effects only could be recog- nized by the agreement of a long series of observed results. And these, as far as they went, were, as might be anticipated, entirely accordant with the idea that the light, being polarized, was, agreeably to the law of polarization, reflected or not at the second incidence, and its heating power of course accom: . panied it. Considering then this portion of the results, ob- tained by the interposition of a glass-screen, they would only show that in this case the term polarization of heat is most im- properly applied. The light is polarized, and whether it be reflected or not at the second incidence, it conveys the heating power with it, which arises simply from its absorption by black surfaces. With respect to the other portion of the effect, or the simple radiant heat, I can only say, that I have been unable, in all the lengthened series of results I have obtained, to perceive the smallest difference in the effects due to it, in the two rec- tangular azimuths of the second glass. These effects, in the instance of non-luminous hot iron, were likely to be obtained in their simplest form ; aud it only remains to be considered how far the radiation from the glass 304 Mr Powell on the alleged Polarization of Heat. reflector may have contributed to*the observed effect. The increase of temperature of the second glass was observed and found very small; and-if any non-reflexion of the regularly transmitted heat had occurred in the proper azimuth, it may,) I conceive, be inferred, that it must have made some percep- tible difference between the long series of results observed in two positions. Not the smallest difference, however, was upon the whole perceptible. Yet in the corresponding case of the lamp, such a difference did certainly appear. ddan With the luminous hot iron again, (the glass screen being interposed,) there was an appreciable difference between the two azimuths; but on the admission of the simple heat, by the removal of the screen, the whole intensity being of course increased, that small difference was in no degree inewcasad with it. io How far results of this description can. be ceosiduaal as tending to decide the question under consideration, it is not for me to determine. But the distinction I have. formerly pointed out between the two species of heating effect in lumi- nous radiations, must be admitted to place the question in a different point of view from that in which it has hitherto been regarded. We have thus to regard Berard’s conclusion, with respect to simple heat, as the essential point; and this con- clusion, (so far as my experiments are to be relied on,) I have unifornly failed ¢ in being able to verify. It only remains for me to express my earnest hope that some experimentalist, better qualified for the task, will be induced to take up the subject. And by the construction of better ap- paratus, and the invention and.- adoption of more satisfactory methods of experimenting, will succeed in bringing this i inte- resting question to a completely decisive termination. It is, indeed, chiefly with the view of suggesting this, that I am in- duced to give publicity to these remarks. Norte. Perhaps it may here, for the sake of some readers, not i irrelevant to state briefly the nature of my former experiments alluded to. I conceive I have shown in those experiments that chet are Mr Powell on the alleged Polarization of Heat. 305 © two distinct ‘species of heating effect emanating together from _ luminous hot bodies. The one transmissible through glass, and affecting bodies according to their darkness of colour. The other not transmissible through glass, and: affecting bodies according to the texture of their surfaces. The ‘solar heat appears to’ consist solely of the first kind!: shies of luminous hot bodies of both; and that of non-lumi- nous hot bodies, solely of the second kind. . ai. ohn My paper, published 1 in 1825, having been eesti a first attempt at an investigation of this kind, has many of the de- fects incidental to an early production. — In particular, the ex- periments were complicated by several circumstances which further consideration shows to have been unnecessary. The essential experiment is in fact one of extreme simplicity. It is only necessary to place a smooth black, and an absorptive white, thermometer near together at a short distance from a luminous source of heat ; sbcieel the degrees risen by one, while the other rises a given quantity as one degree. | Repeat the observation with a glass screen interposed, (keeping them in the same position,) and the inequality of their noe will be found in all cases increased. Thermometers of the most ordinary sensibility are quite suf- ficient ; and the rays from a red hot poker, from the flame of a lamp, or even a candle, give very satisfactory results. Tt will be found on. consideration, that all the interfering causes are such as would tend to diminish the inequality when the screen is used, yet we find it invariably increased. It may here be observed, that I have all along assumed as one of the characteristics of simple radiant. heat. the, general fact of its incapacity to be transmitted. in the way. of direct radiation through solid media acting as screens... To this ge- neral fact, the experiments of Mr Ritchie make one exception, in the instance of transparent screens of great tenuity., "Though some results which I fomerly obtained were at variance with his, yet, from what he has subsequently written, I am willing to admit the superior delicacy of his apparatus. And I may be allowed to take this opportunity (which various causes. have before denied me) of acknowledging the candid tone of his-re- marks on my experiments. _. Relying on that candour, I may NEW SERIES, VOL. III. NO. 11. ocTOBER 1830. U / 306 » Mr Haidinger on Johannite, also be permitted to.remark in general, , that this exception appears to me so remarkable a one that I should be anxious to _ examine whether there may,not yet be found some means of explaining it. The progress of research has tended. to dimi-_ nish the points of resemblance between light and simple } heat. Even the fact of the radiation of heat itself seems very likely to possess little real analogy with the propagation of light. The mode in which heat is in general propagated through screens has been. so satisfactorily traced, and shown to be so essentially distinct in its nature from direct radiation, as to make it a very extraordinary circumstance, that in this one in- stance the heat should possess a new mode of action: and more especially when this property is connected with. the trans- parency of the screen ; a quality to which heat. is in no other case found to bear any reference. These considerations would show the propriety of a careful examination inio every cireum- stance which is likely to afford any solution of the anomaly. Without pretending to enter at present into such an examina- tion, I will content myself with barely suggesting one or two points which might possibly be further inquired into with ad- vantage :—1st, The accuracy and fitness of air thermometers in researches of this nature. 2d, The laws by which the ab- sorption and subsequent radiation of heat is regulated in bo- dies extremely small, and thence in screens of. great. tenuity, whether consisting of fixed substances,.or perpetually renewed films of fluid. 8d, Whether the difference of the conducting powers of bodies continues to display itself when the substances are reduced to a'state of great tenuity, as in the instance of a film of charcoal coating a glass screen. How far any of these causes may be found adequate to explain any part of the diffi- culty I do not in the least pretend to say. 1 leave the con. sideration of them to those who may be better able. to follow up the inquiry. Amel XLV.—On Johannite, a New Mineral Species. | ‘By Ww. Hatpincer, Esq. F. R.S. E. &c. Communicated by the - Author. Txt forms of Johannite belong to the hemiprismatic system. a new: Mineral Species: » 307 I siend observed only two varieties, — are represented in Fig. 12 and 13, Plate IT. Although the erystals are pretty regularly firmer and pos- sess sharp edges, yet they are so very minute, and grouped to- gether in botryoidal concretions, that it becomes very difficult to find out the true form, and still more so. to measure the an- gles. The latter I succeeded only in measuring by approxima- tion as follows: Inclination of @ on a, adjacent = 111°, of a on 6 = 118°, of aon e or @ onc = 87° 28’ of b on ec = 128° $2’, of b on d = 134° 5/, of b on e (over c) = 101° 15’ I did not succeed without rather unlikely hypotheses, in as- certaining the dimensions of any pyramid, which might be con- sidered as the fundamental form of the species. , I have pre- ferred, therefore, to put down the measures of the angles, as T obtained them by the application of the reflective goniome- ter ; while larger and more complicated forms of crystals may be discovered hereafter, which may allow of a more easy and exact determination of all the - (bsg gilang relations of the se- ries of crystallization. try i : On account of the smallness of the orystals, cleavage i is ob- served with great difficulty ; yet I perceived traces parallel to the faces marked a, also parallel to another face, which re- places the sharp edges between b and.c; in other directions, there is imperfect conchoidal fracture. . The surface of the crystals is smooth, the faces 6, d, C, @, are slightly streaked, parallel to their edges of combination. The Johannite possesses vitreous lustre ; its colour is a fine bright grass-green, which becomes pale nent in the streak. The crystals are semitransparent. It is sectile, the hardness = 2.0...2.5, rather. more oti rable than that of hexahedral rock-salt. The weet gravity I found = 3.191, at 59° F It is slightly hitie i water, and occasions a faint taste, more bitter than astringent. Johannite belongs to the order Salt, in the first class of the system of Mohs. As it will. become necessary in future to dispose, into genera and species, the whole contents of this or- der, and to apply consequently systematic denominations to them all, I shall not now by a hasty determination unnecessa- 308° Mr Haidinger on Johannite, rily increase the number of such mames. At all events; it does not belong to the genus vitriol salt. The denomination of Vitriol of Uranium, proposed by John,* recalls to our memo- © ry alchemistical ideas, which are long and deservedly forgotten. It is with the highest gratification that I propose the name of Johannite for the present species; for no mineralogist ever had an opportunity, in paying a compliment to a distinguished patron of his science, to apply to a new species the name of the brother of his prince. I am indebted for this peculiar fa~ vour to his Imperial Highness the Archduke John of Aus: tria. I have endeavoured to remind the latest of future ad- mirers of one of his favourite sciences of a name, upon which we dwell with pleasure in the history of the present age, and thus to preserve, as long as the progress of science shall be at- tributed to the labours of our own contemporaries, the recol- lection of my regard to him. The specimens which I examined I first saw at J oachimsthal, in Bohemia, when I visited that celebrated mining town in spring 1826 with Mr Robert Allan, in the collection of a min- ing officer, Mr Peschka. This collection having been pur- chased by Count Caspar Steruberg, and presented to the Na- tional Museum at Prague, I was fortunate enough to obtain the specimens for examination in spring 1829. I had long ago wished to give the name of Johannite to a species found in the Austrian dominions, and had likewise requested his Imperial Highness’s permission to do so; and I found this species the more agreeable to my purpose, as its green colour contains an allusion to the Alps, the favourite abode of its im- perial namesake. I have been frequently indebted to Professor Zippe for va- rious interesting minerals for examination. I am under parti- cular obligations to. him in the present case, he himself hav- ing already published several valuable papers, and the deter- mination of a new species being particularly interesting. The species itself deserves to be considered as new in mine- ye although John has already published an analysis of ; yet both physical and chemical properties were so imper- mage described, that it is impossible to infer from them, alone * Chemische Schriften, Bd. vi. p. 254. a new Mineral Species. 309 the identity of Johannite with his vitriol of uranium. I owe my full conviction of it, only to the verbal, communication of Mr Peschka, whom I called for expressly for that purpose. Johannite exposed in a glass tube to the flame of the spirit lamp, gives off a considerable portion of water, whereby a dark-brown residue is left, which is friable, and still shows traces of the original crystallization of the mineral. When melted on charcoal with carbonate of soda, and placed on a bright surface of silver, and afterwards wetted, a black spot of sulphuret of silver is formed on that surface. Also a smell of sulphuretted hydrogen is disengaged. If — kept somewhat longer in the reducing flame of the blowpipe, and then again melted with carbonate of soda in the reducing flame, globules of copper are obtained. Johannite forms with borax a fine green glass, both in the oxidating and in the reducing flame. In the latter, the glo- bule sometimes also appears red and opaque on cooling, from the protoxide of copper. When treated with salt of phosphorus, only the green tints appear, owing chiefly to copper in the oxidating flame, and to uranium in the reducing flame. By a long continued blast of the reducing flame, the globule becomes covered with a black metallic surface, if much of the Johannite has been employed. By an addition of tin, the red colour of the protoxide of cop- per is obtained. In a solution of Johannite in nitric acid, caustic ammonia produces a yellow precipitate, but becomes blue itself from copper. The residue comports itself with salt of phosphorus like pure oxide of uranium. _ Johannite appears, therefore, to contain sulphuric acid, water, and the oxides of copper and uranium. We expect to hear even of the exact ratio of these ingredients from Professor Berzelius, to whom Mr Selfstrém was kind enough to take a specimen from me. This species is as rare as it is beautiful. The only speci- mens hitherto known were found in opening some old works near the mine of Elias at Joachimsthal, in Bohemia, in the year 1819, as a coating of fragments of uranium-ore. Free sulphuric acid, as is likewise supposed by John, pro- $10 Notice of a mass of Meteoric Iron bably owing to the decomposition of some species of pyrites, is 10 doubt the cause of the formation of the present species. In the specimens which I examined it is’ > accompanied by acicular crystals of gypsum.” ART. XV. —Notice of a mass of Meteoric Iron nereney dis. ’ covered in Bohemia.* Tue locality where this mass of meteoric iron was found, is’ the slope of a hill near the castle of Bohumilitz, in the circle of Prachin in Bohemia, the estate of Baron Malowetz of Ska- litz, .A ploughman, having on the 19th September 1829, ac- cidentally alighted upon it with his plough, and supposin the mass, which was afterwards found to weigh 103 pounds, to be an ordinary stone, he endeavoured to lift it, and throw it out, but being surprised with the great weight, he thought it must be a precious metal. A small bit of it, however, having been detached by a blacksmith with a hammer, it was recognized to be iron. Dr Charles Claudi, an eminent lawyer of Prague, the proprietor of the neighbouring estate of Cykin, paying a visit to the baron, was shown the mass, and as there are no iron-works in the vicinity, he argued that it might have had a. meteoric origin. This was fully confirmed by Profes- sor Steinmann’s discovery of nickel in it, and by the peculiar structure which is likewise detected in other kinds of meteoric iron by etching a polished surface. Upon the application of these gentlemen, Baron Malowetz presented the whole of this highly remarkable object to the National Museum at Prague. a There can be no doubt that this mass of iron has lain a long time in the soil, the plough having passed over it for ages ; and it must be ascribed only to the heavy rains of last sum-~ mer, that, much soil having been washed away, it came at last within the reach of the plough. Its having been a long time exposed to the agency of air and weather, 1 is also testified by.a thick crust of oxide of iron, with which it was covered when first dug out. * Abstract of several papers in the Jahrbiicher des bohmischen. Museums. No ii. 1830. recently discovered in Bohemia. 3ht No conjectures can be made respecting the age of this mass. There is indeed a notice by Marcus Marci pz KronLanp,* that a metallic mass had fallen from the sky in Bohemia, in the year 1618, but without the locality where it had fallen. According to the account by Professor Zippe, the Bohumi- litz meteoric iron is an irregular lump of a ‘somewhat qua- drangular shape. It is marked on the surface with irregular roundish impressions, of the same kind as other masses of na- tive iron, having a meteoric origin. He describes the colour of the surface as clove-brown, with spots of ochre-yellow, - owing to the oxidation of the surface, which is covered with’a crust of the brown hydrate of the peroxide. Within the co- lour'is paler than the colour of newly filed bar iron, but not so pale as that of the Elbogen native iron. A polished surface, etched with nitric acid, shows the cha- racteristic damask-like delineations first observed by Widmanns- tetten. They are, however, slightly different from these’ in the delicacy and angular disposition of these figures. ‘Those of Elbogen are usually thin and distinctly triangular, meeting at angles of 60° and 120°, whereas in those of Bohumilitz the lines are thicker, and meet at angles not always exactly the same ; those of 70° and 110°, however, are more usually found. The whole appears to be a compound of several’ individuals, which may be distinctly seen, when slices are broken across, or in the fracture of the fragment, first detached by the black- smith. Cleavage may be distinctly traced in planes perpendicular to each other, which leads to the hexahedron as the fundamental form. They were obtained by cutting through the mass, but not entirely, and then breaking across the remainder ; but, on account of the great toughness of the substance, it is general- ly interrupted by the hackly fracture. The mass is traversed by several cracks or fissures, and contains also imbedded nodules of a mixture of plumbago, magnetic iron pyrites, and a white metallic substance, not ex- actly ascertained. The latter, which occurs’ likewise in: small grains disseminated in the Elbogen meteoric iron, occurs here * Millauer, Verhandlungen des hihmischen Museums, 1825. 3. 312 Dr Hibbert’s. Remarks‘on a in larger nodules, particularly in the®places where the iron and the plumbago meet. Someof the nodules of the latter sg 3 nearly an. inch in diameter. Professor Steinmann found the specific gravity to be 7. 146. On dissolving the substance in muriatic acid, hydro-sulphu- ric acid was developed, which being introduced into a solution _ of acetate of lead, gave a small quantity of a proaee ~ sulphuret of lead. A small residue of 1.12 per cent. of the hihi’ was. left,. which was insoluble even in nitro-muriatic acid. It proved to. be a mixture of plumbago, and of small metallic scales of a steel-grey colour. ‘The solution in muriatic acid being boiled with nitric acid, in order to bring the iron into the state of peroxide, was decomposed by carbonate of potassa, and the precipitate digested with caustic ammonia. The blue ammo- niacal solution left gave a residue of 5.11 per cent. of oxide of nickel, by evaporation and subsequent ignition. The result of the analysis of the Bohumilitz meteoric mass: | is therefore : Iron, . 4 94.06 Nickel, 2 J é 4.01 Plumbago, with another metallic substance ! not sufficiently ascertained, if 1.12 Sulphur, . - 0.81 100.00 Art. XVI.—Remarks on a Natural Rocking-Stone of Gra- nite, surmounted by an ancient cross, illustrative of the early Gaulish Costume; observed near the village of Loubeyrat, in the Province of Auvergne, France. By S. HizBert, M. D. F. R. S. E. &c.. Communicated by the Author. Kacnu year the geologist is making the boldest trespasses on the ground which the antiquary, by a sort of prescriptive right, has long claimed. The parallel roads of Glenroy have been celebrated as stupendous. monuments of the labour to which our ancestors subjected themselves in preparing artifi- cial hunting grounds for the royal chace of the red-deer, yet natural Rocking-Stone of Granite, &c. 313 they are now more soberly regarded as effected by the natural agencies of ancient lakes. The rocking-stone, which has given rise to divers erudite dissertations upon the state of me- chanical knowledge among the Druids, is now more rationally attributed to the concentric disintegration which is induced upon certain rocks by atmospheric causes.* Not many years ago the site of every rocking-stone in Britain was care- fully registered as indicating the geographic limits to which the ancient priests of the Celts extended their religious in- stitutes; and when the antiquaries of our British Colonies in the East were employed in identifying the ancient religion of the Ganges with that of the Gaulish Ovates, and when lying Bramins amused the credulous philosphers who confided in them, by the legend that the British islands had been known to their priests in their earliest records under the name of *¢ The sacred islands of the West,” and that in remote times a college of their order had existed there,—then it was that a groupe of detached rocks, or boulders of millstone grit, situated in the West Riding of Yorkshire, which were re- markable for their grotesque weathered forms, and for the natural rocking-stones which long desquamation had induced, were unhesitatingly concluded, from the indications afforded by their name of the Bramham Crags, (that is, for Bramham Crags, read Bramah Crags,) to be the proud existing monu- ments of a Braminic college ! It is imposible to allude to such lucubrations, which are still scarcely obsolete, with any degree of seriousness. If con- ceits like these had gone on, Europe and Asia would have been far too limited fields for Celtic researches. It is remark- able that American geologists have lately described many rocking-stones which exist in the Western World; and if natural objects like these are doomed to be forced into the speculations of our Jonathan Oldbucks, the next disquisition to be expected is one that would assign to the Druids a priority over Columbus, in the discovery and colonization of trans- atlantic regions. But if a sneer has been deservedly excited when weathered * See Dr MacCulloch’s excellent Dissertation on the Granite Tors of Cornwall. 3 314 Dr Hibbert’s Remarks on a. rocks, such as the Logan-stone arf Cheesewring of Cornwall, have entered into mythological discussions, it has been less due to the occasion than to the distorted manner in which such | objects have been contemplated. No one can take the most superficial glance at the religious rites of our Celtic and Teu- tonic ancestors’ without being convinced, that rock worship prevailed among them to a considerable extent ; and, amidst the varied forms which rocks assume, the imagination would fix upon some:of them as resembling the gods of their peculiar beliefs; These would be their Simulacra’ meesta deorum, to whieh frequent allusions are made in the Northern Sagas and elsewhere. And thus, when a superstitious fancy has been ena bled to trace certain human lineaments in the outlines of a large boulder, it would become a symbol of one of the deities of the Fdda.. The Laplanders, a different race, who ‘eventually adopted the religious: tenets of the Norwegians, were in the habit, according: to Scheffer, of convertmg any odd-shaped log of wood that struck their imagination in a similar manner into an idol of ‘The Thunderer. No wonder then that such as- semblages of rocks as shewed singular diversities in form from the effects of weathering should be particularly consecrated: And during the prevalence of rock worship there is reason’ to suppose that the ancient Gauls set apart such sites for the celebration of Druidic mysteries, and that here they erected the cromlech or sacrificial stone. In‘countries, therefore, occupied by this people, however widely they might: have been separat- ed, we ought to find indications of the similar religious uses to which rocks were submitted, by the similar artificial forms which they were made to»assume. Nor shall: we be disap- pointed. If the cromlech is to: be seen inmany parishes of Wales, it is likewise to, be detected: in’ many aati hint of the:ancient Gaulish province of Auvergne. °!o)(5) 5 But still.the question arises, what direct proof have we’ ci the rocking-stone had any connection. with the religious belief — or veneration of the ancient inhabitants of Gaul? This answer is not so easily made. The equipoised massive stone is alluded to by Pliny, though merely regarded by him asa’ natural eu- riosity ; and an indecisive reference is made to it in The Ar- gonautics of Apollonius Rhodius ;—and ema is all. Inthe ab- 4 natural Hocking-stone of Granite. 315 sence, then, of a direct proof of its religious use or application, I have long conceived that if it had been really held in reverence by the early inhabitants of Europe, the same notice | would have been taken of it in a remote Christian period, as of’ the open temple which was formed by circular’ ranges of upright stones. The missionaries who first preached the Gospel in Britain were aware that the task of conversion would not be suddenly effected; and hence it was a proper recommendation of St Augustine that a temporizing system should. be adopted. Wherever, therefore, a pagan fane existed, no attempt was made to abruptly destroy it, but, in order to gradually wean the natives from idolatry, permission was obtained that a Chris- tian church should be erected’ in its vicmity. ‘This accompa- niment has been accordingly sooften noticed, that it is fami- liar to every antiquary. Another question, however, now arises, whence 1s'it that no similar association has been noticed. in certain other forms of rocks, natural or artificial; which have been considered usetrumental to pagan worship ? It would, for instance, be a strong indication of the religious: use to which the rocking-stone might have been applied, were it either found in contiguity or junction with a Christian cross. That nosuch association should have been discovered im England can create little surprise, when we consider what efforts were made by the early reformers, and afterwards much more so' by the puritans, to destroy all relics of the cross, which were regarded by them as so many genuine marks of The Beast. Among the moun- tains of Auvergne, however, where similar havoc has not been made, the search after such an accompaniment will’ be found more successful. In this country, where the natives, from their peculiar dark complexion, show decisive marks of a Celtic ori« gin; where the monuments of antiquity which exist resemble those of Wales and Cornwall, I have at length found the rocking-stone surmounted by the Christian cross.» Its site is a tolerably high ground, near, as far as I can estimate, to the village of Loubeyrat. A drawing of it is annexed: (See Plate II. Fig. 11.) | This rocking-stone, which is composed of granite, is not very considerable. Its dimensions are from two. to three and a-half feet broad by twenty inches in height.» It is nicely 316 - Dr Hibbert’s: Remarks on a poised upon another stone of granite ; ‘but in order to prevent it from rocking after the cross had been superimposed, its stea-' diness has been secured by several rude blocks of stones, which are jammed into the interval round its base of support. These are not represented in the drawing. On the top of the rock- ing-stone a square niche has been let in for the reception of a pedestal destined to the support of the cross. This pedestal is two feet one inch in height; its base is twenty-two inches square, from which it gradually lessens to the summit, which is only fifteen inches square. On one side of the pedestal two figures are sculptured, which from their dress appear of great antiquity. The garb is like that of, certain figures which are to be found on the capitol of the more ancient part of the Church of Volvic in Auvergne, which is attributed to so early a date as the sixth century, but was certainly not later than the eighth or ninth. But the speculations connected with this altar, I shall separately consider. _ An inscription appears un- der the figures, which, from being much worn, is become unin- telligible. I could only make out the word Parpon 3 the re- maining letters probably alluded to the number of days of par- don which this cross gave to the venerator. ‘The cross, how- ever, which was contemporary with the pedestal, has been re- moved, as the one by which it has been replaced, though’ ancient, is evidently of later workmanship. It has been wrought from the black lava of the country, and has a height from the pedestal of about two feet. From the tenor of the foregoing observations it is evident, that if a doubt be placed upon the legitimate authority of the antiquary to warn the geologist off his manor when he assigns ~ the formation of the rocking-stone to the disintegrating effect of atmospheric causes, the geologist, on the other hand, has no right, though with much older pretensions of title, to include within his own pale the subject of contention, and to make it’ a part and parcel of his own demesnes. sally Regarding, however, the particular use to which rocking- stones were applied, notwithstanding they have been the sub- ject of infinite learned memoirs, we are ‘still most imperfectly informed ; nor is it at all probable that the obscurity will ever natural Rocking-Sone of Granite, &e..— 317 be removed. As they are the products of every country where loose detached rocks of a particular structure have been sub- mitted to the operation of atmospheric agents, it is to be ex- pected that the fables assigned to their origin would be regulat- ed by the peculiar mythology of the people among whom they have become the object of notice and wonder. In Greece two standing stones, one of which was a rocking-stone, have been attributed to Hercules, who is said to have reared them in memory of the two sons of Boreas, whom he slew in the sea- gut Tenos - *¢ And one still moves, how marvellous the tale ! With every motion of the northern gale. Fawkess Apollonius, Book i. line 1676, &c. Borlase, whose uncontrolled fancy has comed more antiquari- an legends than almost any other man, stoutly maintains from this passage that it was quite uswal with the ancients to place, for a religious memorial, one vast stone upon another so equally poised that the least external force, even a breath of wind, could cause a vibration. This is, to say the least of it, a most illogical inference, as the very circumstance of the vibrating property of such immense stones having been attributed to the supernatural strength of Hercules, ought to have afforded an argument for their comparative rarity. In the British islands also, where rocking-stones are far more frequent than in Greece, and where it is the common voice that they were the work of those everlasting rock-pilers the Druids, these natural objects have afforded themes for the most amusing conjectures, as that when violently pushed and reverberating, they were suited to alarm the country upon the approach of an enemy ;—or that they were used for divi- nation, the vibrations serving, with the assistance of a little se- cret priest-juggling, for the determination of national questions, or, as an ordeal, for judiciary purposes ;—and so plausible, in- deed, was this last fable, which was invented by Toland, that it has been made to form a very striking imcident in Mason’s classical drama of Caractacus : Thither youths Turn your astonish’d eyes ; behold yon huge 318 Dr Hibbert on a Rocking-Stone of Granite. And unhewn sphere of living adamant, Which, pois’d by magic, rests its central weight On yonder pointed rock: firm as it seems, Such is its strange and virtuous property, — It moves obsequious to the slightest touch Of him whose breast is pure: but to a traitor, Tho’ ev’n a giant’s prowess nerv'd his arm, It stands as fix’d as Snowdon. No reply ; ~ The Gods command that one of you must now Approach and try it! But to return to the specimen of this kind at Auvergne.— I have little more to observe regarding it, except that the pro- vince in which it occurs is remarkable for the indubitable me- morials of rock worship or reverence, to which in Britain we give the name of Cromlechs.. In fact, no portion of ancient Gaul can perhaps boast of a greater number of them, and hence, the costume of the figures represented on the surmount- ing pedestal of the cross becomes. somewhat interesting, as il- lustrating the ancient attire of the Gael. It has been long since remarked by Shaw in his History of Morayshire, that when Sidonius Apollinaris, a bishop of Auvergne, was in the fifth century particularizing the dress of ‘‘ a Gothic Gentle. man” of his country, he was actually describing the costume of the Scottish Highlands. ‘‘ He covers his feet to the ankle with hairy leather or rullions; his knees and legs are bare ;_ his gar- ment is short, close and party coloured, hardly reaching to his hams; his sword hangs down from his shoulder, and his buckler covers his left side.”. It must be confessed, however, that few of these characteristics can be traced in the costume of the two figures rudely sculptured upon the ancient stone of Auvergne, with the exception of what may be fairly implied to, be a kilt, exactly like, that which the Highlanders wear at the. present day, and which, as Apollinaris states, scarcely reaches to the hams. But in discussing the antiquity of the Highland kilt, I~ am aware that I am entering upon debateable ground, and shall therefore abruptly bring this memoir toa close : Non nostrum inter vos tantas componere lites. , Prof. Stromeyer on Pyrophosphoric Acid and its Salts. 319 Art. XVIL=-On Pyrophosphoric Acid sid ‘tel Sudha By Professor StROMEYER of Gottingen. Proresson StRoMEYER remarks, that one ofhis pupils noticed, _ several years ago, that phosphate of soda, after being heated to redness, yields a white instead-of a yellow precipitate with nitrate of silver, This observation was confirmed by the Pro- fessor at, the time ; and he likewise found, as Gay-Lussac has done lately, that the acid prepared by the action of nitric acid on phosphorus, after exposure to a red heat, precipitated sil- ver in the same manner. ‘The product of the combustion of phosphorus in air or oxygen gas was observed to possess the same property ; but the subject had not further occupied his attention until the essay of Mr Clarke, published in the for- mer series of this Journal, (vol. vu. p. 298,) induced him to renew the inquiry with the view of explaining the nature of the change. Stromeyer confirms the statement of Clarke, that the con- version of common phosphate into pyrophospate of soda is attended with no other change than the escape of a little water. He rightly argues that the change cannot in any respect be similar to that which a red heat occasions in sulphite of soda, which, without loss or gain in weight, is converted into sul-- phate of soda and sulphuret of sodium, since phosphoric be- comes pyrophosphoric acid when heated alone, as well as when combined with an alkaline base. _ In fact, Stromeyer’s re- searches satisfactorily prove the two acids to be essentially dis- tinct, though in the ratio of their elements they appear to be identical. + One obvious distinction between these acids is in the differ- ence of the salts which they form with oxideof silver. ‘hese compounds differ not only in colour, but in specific gravity. The density of the pyrophosphate is 5.306, while that of phos- phate of silver is 7.321 ; and hence, in precipitating equal quan- tities of silver by pyrophosphate and phosphate of soda, the pre- cipitate occasioned by the former is much more bulky than that * Abstract of an essay read at the Royal Society of Gottingen in Ja- nuary 1830. 820 Prof. Stromeyer on Pyrophosphoric Acid and its Salts. produced by the latter. Theygare both pulverulent when dry, and in that state are anhydrous ; but the pyrophosphate at the moment of precipitation, retains a little combined water, though, as in the case of carbonate of facond the union soon spontaneously ceases. ee ‘ Pyrophosphate of silver fuses with extreme facility, even ata temperature below that of redness, yielding a dark brown coloured liquid, which, without suffering the least appreciable decomposition, becomes a radiated crystalline mass on cooling. By the first impression of heat, long before fusion, it changes to brownish yellow, and retains when cold a shade of the same colour. Phosphate of silver, on the contrary, is very infusible ; so that it may be heated in a glass tube, or on platinum foil, to full redness, without being fused. Its colour changes to a reddish-brown by very slight elevation of temperature; but, as it cools, the original yellow tint is restored. At a white heat it is fused ; and then, like the pyrophosphate, it assumes a dark brown colour, but regains the yellow on cooling.’ If kept for any time in a fused state, a portion of pyrophosphate is generated ; and, consequently, the mass becomes more fus- ible, and acquires a paler tint. A very minute quantity of pyrophosphate greatly increases the fusibility of the Eee of silver. Phosphate of silver is blackened by exposure to light, while | the pyrophosphate receives a reddish tint. They are both insoluble in water, and unchanged by boiling. | ‘Phe pyro- phosphate, like the phosphate, is easily dissolved by nitric: acid, and is thrown again by ammonia; but if heated with nitric acid, ammonia then precipitates the yellow phosphate.’ By muriatic acid it is instantly decomposed, with production of chloride of silver, and separation of pyrophosphorie «acid. Sulphuric acid acts like the nitric ;. but no change is produced by acetic acid. It is readily dissolved by means of ammonia, and falls wholly unchanged, when the solution is neutralized. - Phosphate of silver and pyrophosphate of soda may be boiled together without the least change ; but.double decom- position is instantly produced by boiling pyrophosphate : of silver with phosphate of soda, the insoluble salt changing from white to yellow. Other insoluble pyro-phosphates,. such as Prof. Stromeyer on Pyrophosphoric Acid and its Salts, 321 pyrophosphate of lead, copper, and zinc, undergo a similar decomposition when boiled with phosphate of soda. Consist- ently with these facts itis found, that when nitrate of silver is gradually added to a mixture of phosphate and pyrophos- phate of soda, the first precipitate consists of phosphate, and the latter of pyrophosphate of silver. It is hence inferred by Professor Stromeyer, that in the intensity of its attraction for salifiable bases phosphoric acid exceeds the pyrophosphoric, —a circumstance which aloue suffices to establish an essential distinction between these compounds. | . Vhe insoluble pyrophosphates are in general easily dissolved in a/solution of pyrophosphate of soda. This has been ob- served with the pyrophosphates of silver, lead, copper, nickel, cobalt, uranium, bismuth, manganese, protoxide of mercury, glucina, and yttria; and, therefore, in preparing these salts by way of double decomposition, it is important to avoid an excess of the precipitant. To this remark the pyrophosphates of peroxide of mercury, oxide of chromium, baryta, strontia, and lime, are exceptions ; but even the three latter, when re- eeutly precipitated, are dissolved in a small degree by pyro- phosphate of soda. ‘The circumstance here adverted to, ap- pears to depend on the formation of double salts which are very soluble in water. It forms a striking contrast with the phosphates ; for the insoluble compounds formed by double decomposition with phosphate of soda, are, almost without exception, quite insoluble in excess of the precipitant. Stromeyer concludes, from the preceding facts, that pyro- phosphoric acid is essentially distinct in chemical constitution from the phosphoric; and that it is equally well entitled: as phosphorous and hypophosphorous acids to be regarded as a distinct acid of phosphorus. But the nature of the difference, whether arising from a different stage of oxidation, or from any other cause, does not appear, and requires for its eluci- dation the aid of additional experiments. As the pyrophosphoric acid obtained by heating sieteiilenia acid to redness, as well as that which is formed by the com: bustion of phosphorus, loses, by exposure to the air, its pro- perty of giving a white precipitate with nitrate of silver, and then resembles in every respect common phosphoric acid, it NEW SERIES, VOL, lil. NO. 11. ocTOBER 1830. x 322 Prof. Stromeyer on Pyrophosphoric Acid and its Salts. appeared probable that the conyersion of the latter into the former was owing to deoxidation, and that pyrophosphorie may be regarded as a hypophosphoric acid, intermediate be- tween phosphoric and phosphorous acids. . It cannot, however, be a variety of phosphatic acid, since it does not reduce the salts of mercury, nor is it inflamed by a strong heat ; but the idea of its being less highly oxidized than phosphoric acid, is, nevertheless, supported by the analogy of phosphorus with | sulphur, selenium, and arsenic, which do not pass into a max- imum of oxidation when burned, and when fully oxidized are easily deprived of some of their oxygen. Another cireum- stance, favourable to the same line of argument, is, that pyro- phosphoric acid and pyrophosphate of soda, when heated with: nitric acid, are speedily converted into phosphoric acid and phosphate of soda. Against this opinion, however, the follow- ing facts are decisive .—that during the change just mentioned, the nitric acid does not appear to undergo the least trace of decomposition ; that a similar conversion is effected not only by sulphuric, muriatic, and acetic acids, but even by the phos- phoric ; that: free pyrophosphoric is converted into phosphoric acid by mere boiling in water, without this fluid suffering the slightest decomposition ; and lastly, by the change of phos- phorie acid and phosphate of soda into. pyrophosphorie acid and pyrophosphate of soda being unattended by any evolu- tion of oxygen gas. 0 Nor can it be maintained that the pyrophosphoric is an nioxy: genized phosphoric acid. Phosphate of soda, when heated to redness, does not absorb any oxygen from the atmosphere, nor is any hydrogen or phosphorus evolved: the salt, in fact, loses nothing, as Clarke observed, but a small quantity of water. Nor does the difference between phosphate and pyrophosphate of silver depend on the presence of water in one of them, since they are both anhydrous ; and the facts above-mentioned, establishing a decided contrast between the phosphates and — pyrophosphates in general, sufficiently prove that the pheno- mena cannot be owing to a mere difference in the ratio of acid and base. Stromeyer is therefore disposed to consider the two acids as differing, in chemical constitution, rather in the 3 ‘Prof. Stromeyer on Pyrophosphoric Acid and its Salts. 323 “mode in which their elements are arranged, than in the pro- portion in which they are united. In order to determine this point with certainty it was ne- cessary to make a comparative analysis of a phosphate and pyrophosphate containing the same base, and carefully to in-- vestigate, not only the composition of the pyrophosphate, but the phenomena attending its. conversion into the corresponding phosphate. The pyrophosphate of silver was selected for this ‘purpose. - Asa mean of two experiments, Stromeyer found that 100 parts of pyrophosphate of soda, when decomposed by nitrate of silver, yield 222.085 parts of pyrophosphate of silver. Known weights of fused nitrate of silver were then precipitat- ed by phosphate and pyrophosphate of soda; and as the mean. _ of two experiments with each, and estimating 100 parts of the fused nitrate to contain 68.6 of oxide of silver, it was found that 118 parts of oxide of silver unite with 38.36 of pyrophos- phoric acid, and with 22.96 of phosphoric acid. The composition of these salts was also ascertained by dis- solving each in dilute nitric acid, and precipitating the silver, in some instances with muriatic acid, and in others by sulphu- retted hydrogen. The results closely corresponded with each other, and with those above stated. As a mean of all the ana- lyses, it follows that phosphate and pyrophasphate of silver are thus constituted : | Phosphate of silver. Pyrophosphate of silver. Oxide of silver, 83.455 118 75.389 118 Acid, - 16.545 23.394 24.61 3852 100.000 141.394 100.00 156.52 . The relative quantity of the two acids, united with the same quantity of oxide of silver, is in the ratio of 23.394 to 38.52, oras3to5. To this great capacity of phosphoric acid is to be ascribed the acid re-action of a solution in which nitrate of silver has been decomposed by phosphate of soda; a circum- | _ stance by no means confined to nitrate of silver, but which occurs with salt containing.a strong alkaline base, such as lime and baryta, and is the cause of some of the precipitate being re- 324 Prof. Stromeyer on Pyrophosphoric Acid and its Salts. tained in solution. For thegsame reason, when phosphate of soda is exactly neutralized .by phosphori¢e acid, and is. con- verted by heat into pyrophosphate, the resulting salt is meng: | ly alkaline. It yet remained to ascertain how much phosphate of ie would be obtained from a given weight of pyrophosphate of soda and pyrophosphate of silver, when the acids of these salts is changed into phosphoric acid, For this purpose, | 077 gram- mes of pyrophosphate of soda was converted into a phosphate, by being boiled with nitric acid, and: after neutralizing with soda, the phosphoric acid was precipitated by nitrate of silver. ‘the resulting phosphate of silver weighed 3.40 grammes. Stromeyer then dissolved 1.712 grammes of pyrophosphate of silver in dilute nitric acid,—threw down the silver by sulphu- retted hydrogen,—converted the pyrophosphoric into phosphoric acid, and by means of nitrate of silver, employed as in the pre- ceding analysis, he obtained. 2.543 grammes of phosphate of silver. This last experiment was repeated with 2.336 gram- mes of pyrophosphate of silver, which yielded 3.350 | of phosphate of silver. These experiments, accordingly, afford decisive piiidamnes that, during the conversion of pyrophosphoric into phosphoric acid, as also in the reconversion of the latter into the former, the weight of the acids do not suffer the least change. They confirm, therefore, the supposition above-mentioned, that these acids are completely identical in the ratio of phosphorus and oxygen, and that the essential differences between them are referable solely to the manner in which their elements are com- bined. We. obtain then in these acids, a new and decisive proof of the fact, that the same elements, though united in the same proportion, may give rise to compounds which differ essentially in their physical and chemical properties ; and that, consequently, changes in the constitution of many substances may take place, without any accompanying change i m the re- — lative weight of its ingredients. This fact, which in its conse- — quences is of the greatest importance, lays a wholly new field _ of most interesting chemical inquiry, by which many pheno- mena, not previously accounted for, will receive a satisfactory explanation. From this source we may anticipate ‘very m= Dr Knox on the Second Stomach of certain Cetacea. 325 portant results, illustrative of the chemical nature of organic substances; and be thus enabled to perceive how it is possible for so small a number of elements to give rise to such nume- rous and diversified combinations. It will readily be anticipated that the observation of Dr Engelhart, ‘ that a solution of albumen is precipitated by re- cently ignited phosphoric acid, while no turbidity is occasion- ed by phosphoric acid which has not been heated, depends on the formation of pyrophosphoric acid. This fact has been al- ready stated by Gay-Lussac, (Annales de Chimie et de Phy- sique, xli. 332,) and is confirmed by Stromeyer. Albuminous solutions will hence afford an easy mode of distinguishing pyro- phosphoric from phosphoric acid. Art. XVIII.—Notice regarding the nuture of a peculiar Struc- ture observed in the Second Stomach of certain Cetacea, gene- rally considered as simply glandular, but seemingly ana- logous to the Electric Organs of the Torpedo and Gymnotus. Communicated in a Letter to the Editor from Dr Knox. To which is annexed the Microscopical Examination of the Structure by Dr Brewster. Dear Sir, NEwinetTon Piace, June 1830. Aw investigation which I made some time ago into the denti- tion of the Dugong and Cetacea, led me to re-examine several points in the anatomy of these curious animals, and amongst other structures then brought before me, that of the second sto- mach in the small species of porpoise caught so frequently in the adjoining Frith and German Ocean, particularly attracted my attention. I regret, that, at the present moment, I have not leisure so to arrange my notes of these dissections, as to fit them for publication in the Journal conducted by you, and that, owing to this, I shall be forced to limit myself to a very brief notice. In accordance with the language of all anatomists, I shall speak of this species of the Cetacea as having four stomachs, this being the usual way of describing complex stomachs; as those of the ox, sheep, deer, antelope, camel, and whale. 326 Dr Knox on the Second Stomach of certain Cetacea. My own opinion, as explained more fully to the Royal Society of Edinburgh, in a Memoir I had the honour to submit to them during the course of last Winter Session,:is, that no ani- mal possesses more than one stomach, divided more or less by compartments, and thus assuming the appearance of one or more cavities, which anatomists have unhappily designated as one or more stomachs. Now, in accordance with this language, which, however inaccurate, by reason of its universality’ re- quires being respected, I shall speak of the second cavity in the stomach of the porpoise as being the second stomach, The gullet of the porpoise, composed of the usual mem- branes or tunics common to it with others of the mammalia, terminates in a somewhat elongated and tolerably capacious pyramidal-shaped bag, to which we shall give the name of first stomach. In this we find externally, and immediately invest- ed by the peritoneal tunic, a strong muscular coat of fibres spread uniformly over the surface, continuous upwards with the muscular layers of the gullet, and downwards with those which, ina similar fashion, envelope the second stomach, occu- pying the same situation relative to the peritoneal tunic in it as in the first. The muscular tunic of the first stomach is seemingly composed of two distinct layers, separated from each other by a layer of cellular membrane, and the fibres are chiefly longitudinal and circular. Within these two there is the usua! celluloso-vascular layer, and it has within it a mu- cous membrane, covered by a strong epidermic covering. On maceration, we can separate from the mucous surface of the gullet a double epidermic covering, but one only seems to in- vest the first stomach. To this cavity the branches of the nervi vagi (which com- paratively are very large and distinct, ) do not proceed i in any great abundance ; their course is rather towards the second steal whose structure I shall now endeavour to describe. The capacity of the second stomach or cavity is less than that of the first, and its structure is altogether and most remarkably different from it. ‘The communication is by an aperture ad- mitting the fore-finger, and here the textures of the first sto- mach suddenly cease. The epidermic covering and subjacent mucous membrane cease, and there is substituted for them a © Dr Knox on the Second Stomach of certain Cetaceca. 327 perfectly smooth membrane, without. villosities or glandular structures: it has a good deal the appearance of a serous mem- brane. . This closely invests a series of fibres, which externally recovered in by an extremely vascularand cellular tunic. These fibres are not muscular, and have no resemblance to any glandu- _ lar structure, excepting perhaps the tubular part of the kidney. They are placed perpendicularly, and close to each other be- twixt the two membranes I have spoken of ; they stand out, therefore, everywhere from the external surface of the inner membrane of this stomach like a pile of velvet enclosed by thin lamine or plates. Outside the celluloso-vascular lami- na muscular layers exist, continued from those of the first sto- mach, and transmitted over the second to the third. The in- terior of this second cavity, when laid open, presents a series of longitudinal and transverse elevations, which bear a con- siderable resemblance to the interlocking of the fingers in each other. To this stomach the greater part of the nervi vagi are distributed. | The third and fourth stomachs or stomachal cavities, have been very carefully described by the Baron Cuvier, and by all systematic writers on comparative anatomy. The question raised by Camper, as to the number of the stomachs in this ani- mal, does not merit particular notice. ‘The accompanying rude design will perhaps explain to the non-professional reader the appearances I have endeavoured to describe. I forbear for the present all speculations as to the nature of these organs. That they are not muscular is to me evident; but future ob- servation and experiment can alone determine whether or not I am correct in supposing them analogous to electric organs, that is, fitted to exercise electric phenomena as connected with the digestion of the food. Since writing the above, the structure in question has been examined microscopically by Dr Brewster. The result of his examination is as follows: ‘s I have examined the piece of stomach you have sent me of one of the Cetacea. It seems in its wet state to consist of tubes _or fibres perpendicular to the two membranes which enclose - them, thus, AMIVNTAN and the upper surface of one - of ‘the 328 Dr Brewster on the double refraction produced — membranes is covered with hollows or depressions correspond ing with the extremities of the tubes or fibres. A more minute examination, conducted in a different way, proves these perpen- dicular portions to be tubes. In order to dry the substance I pressed it between folds of bibulous paper, and the conse- quence of the compression was, to press together nearly all the tubes, and make the whole one dense mass of a dark > brown colour; but when it became dry and slightly indurated, I drew it out as if it had been India rubber, and the tubes - opened and the mass became white, in consequence of the re flexion of the light from the separated. fibres. \ The whole of it consists of fnelibies interlaced, having a remote reacinbletee to the pith of certain plants. cf hie Art. XITX.—On the production of regular double refraction in the Molecules of Bodies by simple pressure; with observations on the origin of the doubly refracting structure. By Davin Brewster, LL. D. F.R.S.L. & E.* Iw various papers already printed in the Philosophical Trans- actions, I have had occasion to show that the phenomena of © double refraction may be produced artificially by certain changes in the mechanical condition of hard and soft solids. +. In all these cases the phenomena are related to the form of the mass in which the change is induced ;_ and in the case of hard and elastic solids, they vary with any variation of form which alters the mechanical state of the particles. In isinglass and. other bodies to which double refraction has been communicat- ed by induration, the particles take a permanent position, which is not altered by any change of shape; but still the phenomena exhibited by a given portion of the mass are re- lated to the surfaces where the indurating cause operated, and also to those by which the isinglass was bounded; and. they. depend on the position which that portion occupies in the ge~ “neral mass. In all these cases the phenomena are entirely different from * From the Phil. Trans. 1830. | + Phil. Trans. 1814; 1815; pp. 1, 30, 60; 1816, pp. 46, 56-00 9 by pressure in the molecules of bodies. 329 those of ‘regular crystals, and in none of them is the doubly refracting force a function of the angle which the incident nd forms with one or more axes given in position. : As long ago as 1814-1 communicated to the Royal Sociek the following experiment on the depolarizing structure of white ) wax and resin: » ~ + When resin is mixed with an equal: part of white wax, and is pressed between two plates of glass by the heat of the hand, the film is almost perfectly transparent by transmitted light, though of a milky white appearance by reflected light. It has not the property of depolarization when the light is inci- dent vertically ; but it possesses it in a very perfect manner at an — incidence, and exhibits the segments of coloured rings.”* The subject of double refraction was then so little develop- ed that this experiment excited no notice; and it was only brought to my own recollection by the accidental appearance of the specimen itself. This depolarizing film has suffered no change by remaining fifteen years between the plates of glass. The vertical line along which it is destitute of the property of depolarization is a single axis of double refraction ; and the coloured rings at oblique incidences are produced by. the in- élination of the refracted ray to the axis of double refraction. In order to examine this remarkable effect under a more gene- ral aspect, I made a considerable number of such plates with different kinds of wax, and with various proportions of resin, and I was led to results which seem to possess considerable interest. When the white wax is 5 tecleeidh alone and cooled dein two plates of glass, it consists of a number of minute particles, each possessing double refraction, but having their axes turned in all possible directions. If the film of wax is made extreme- ly thin, the particles are not sufficiently numerous to exhibit any action upon polarized light. When resin alone is melted and cooled in a similar manner, it exhibits no doubly refracting structure, whether it indurates » slowly or under the influence of pressure. * Phil. Trans, 1815, pp. 31; 32. 330 Dr Brewster on the double refraction produced If resin and white wax:are mixéd in nearly equal proportions, the compound possesses considerable tenacity.. When a propor- tion of it is melted and cooled between two plates of glass, it shows the quaquaversus polarization of bees’-wax, the axes of the elementary particles being turned in every direction. It possesses a considerable degree of opalescence, and a luminous body seen through it is surrounded with nebulous light, This imperfect transparency evidently arises from the reflexion and refraction of the rays in passing from one molecule to another, occasioned by a difference in the refractive power of the ingre- dients, or by the imperfect contact of the particles, or by both these causes combined. In order to observe the modifications which these phesiiguien received from pressure, [ took a few drops of the melted com- pound and placed them in succession on a plate of thick glass, so as to form a large drop. Before it was cold, I laid above the drop a circular piece of glass about two-thirds of an inch in diameter, and by a strong vertical pressure on the centre of the piece of glass, I squeezed out the drop into a thin plate. This plate was now almost perfectly transparent, as if the pres- sure had brought the particles of the substance into optiens contact. If we expose this plate to polarized light, we shall find that it possesses one axis of positive double refraction, and exhibits the polarized tints as perfectly as many crystals of the mineral kingdom. ‘The structure thus communicated to the soft film by pressure does not belong to it as a whole, nor has it only one axis passing through its centre like a circular piece of un- annealed glass. In every point of it there is an axis of double refraction perpendicular to the film, and the doubly refracting force varies with the inclination of the incident ray to this axis, as in all regular uniaxal crystals. When the two plates of glass are drawn asunder, we can remove one or more por- tions of the compressed film, and these portions act upon light exactly like films of uniaxal mica or hydrate of magnesia, and develope a doubly refracting force of equal intensity. This remarkable experiment presents an interesting subject of inquiry. That the regular double refraction of the film is, developed by. the agency of pressure cannot be doubted ; but -by pressure in the molecules of bodies. 331 it does not at first sight appear whether it is the-immediate effect of the pressure, or is the same doubly refracting force which produces the quaquaversus polarization that takes place when the resinous film indurates without constraint. In this state of the film the axes of double refraction are clearly turn- ed in every conceivable direction ; and it is impossible to sup- pose that a pressure in one direction could suddenly arrange all these axes in parallel positions. ‘The double refraction of each particle of the film has therefore been developed by the compressing force similarly applied to them ; and in producing this effect, it must have deprived each particle of the doubly refracting structure which it previously possessed. The sub- stitution of one doubly refracting structure for another may be easily effected in many bodies. Even in regular crystals we can by heat or pressure modify or remove their double re- fraction. Nay, we can take away one axis from a biaxal crys- tal, and communicate a second axis to an uniaxal one. When the doubly refracting structure is produced by induration, we can remove it wholly by pressure, and replace it with another even of an opposite character ; and when it is generated: by the living principle, as in the case of the crystalline lenses of animals, we can take it away entirely, and substitute a new and more powerful doubly refracting structure by induration. We may therefore consider it as clearly established that the uniaxal double refraction of the resinous mass has been com- municated to the individual molecules by simple pressure ; the increased transparency arising from the molecules being brought into closer contact, and the regular double refraction from the variable density impressed upon each elastic mole- | cule, and symmetrically related to the axis of pressure. The effect thus produced on the resinous mass is precisely the same as what would take place by subjecting elastic spheres to a re- gular compressing force. ‘The axis of pressure becomes an axis of positive double refraction, and the double refraction increases with the inclination of the ray to the axis, and be- comes a maximum in the equator of the molecules. By this view of the preceding facts, we are led to a very simple explanation of the origin and general phenomena of double refraction in regular crystals. That this property is 332 Dr Brewster on the double refraction produced not inherent in the molecules theniSelves may be easily proved. The particles of silex, for example, do not possess it in their separate state. In tabasheer, in many opals, and in melted quartz, there is not the slightest trace of the doubly refracting structure: but when the particles of silex in solution are al- lowed to combine, in virtue of their polarities or mutual affini- ties, they then instantly acquire, at the moment of their com- bination, the property of double refraction, and they retain it while they continue in this state of aggregation.. The manner | in which this takes place may be easily conceived : a number of elastic molecules existing in a state of solution, or in a state of fusion, are kept at such a distance by the fluid in the one case, and by the heat in the other, as to preclude the opera- tion of their mutual affinities; but when, in the process of evaporation or cooling, any two molecules are brought toge- ther by the forces or polarities which produce a crystalline ar- rangement, and strongly adhere, they will mutually compress — one.another, and each will have an axis of double refraction in the directions of the line joining their centres, in the same man- ner as if they had been compressed by an external force. From the phenomena of crystallization and cleavage, it is obvious that the molecules of crystals have several axes of at- traction, or lines along which they are most powerfully attract- ed, and in the direction of which they cohere with different degrees of force. Guided by the indications of hemitrope forms, and supposing the molecules to be spherical or spheroi- dal, we infer that their axes are three in number and at right angles to each other, and are related in position to the geome- trical axis of the primitive form. In like manner the pheno- ‘mena of double refraction are related to the same axis of the primitive form, and may be all rigorously calculated by a re- ference to three rectangular axes. In uniaxal crystals, the three axes A, B, C must be such that two of them are equal and of the same name ; while the third, corresponding with the apparent axis, may be of the same or of a different name. In biaxal crystals, the three axes A, B, C are unequal, and ‘in crystals with no double refraction the axes are equal and de- stroy each other.* ! ) Spee *-In uniaxal crystals, the resultant of the two equal axes A, B may by pressure in the molecules of bodies. 383 This approximation of these two classes of facts is too re- markable to be accidental, and would go far to establish their dependence, even if it were not indicated by other aenent which I shall proceed to illustrate. Among those crystals which have the obtuse rhomboid for alate primitive form, there are many with one axis of nega- tive double refraction, and only one or two with one axis of positive double refraction. In. the former, the negative doubly refracting structure will, be produced round the axis of the rhombohedron by the compression arising from attrac- tions in the direction of two equal rectangular axes A, B, which will dilate the molecules in the direction of the third axis C, and make it a negative axis of double refraction, equal in intensity to either of the other two. Here we require the combination only of two axes; but if we suppose that there is in the direction of C a third axis of attraction either more or less powerful than the other two, then if it is less powerful, the compression of the molecules produced by it will diminish _ the dilatation arismg from the united action of A. and B, but will still leave an unbalanced dilatation, or a single negative axis of double refraction in the axis of the rhomb. , If C, on the contrary, is an axis in which the attractive force of the molecules is greater than along A and B, the compression which it produces will exceed the dilatation aris- ing from A and B, and we shall have an axis of compression along C, or an axis of positive double refraction as in quartz and dioptase*. The same observations are applicable to mi- nerals that crystallize in the pyramidal form. have any relation to C but that of equality ; excepenny when C is of a dif- ferent name from A and B. In biaxal crystals, any two axes A, B, may be shined into dnd A+C,B4C, + €. See Phil. Trans. 1818. * Since this paper was written, I have seen the very valuable researches of M. Savart on the structure of crystallized bodies as developed by sono- rous vibrations. The curious result of his experiments, that the axis of calcareous ‘spar, a negative axis of double refraction, is the axis of least dlastieity, while the axis of quartz, an axis of positive double refraction, is the axis. of greutest elasticity, harmonizes in a remarkable manner with the above views. 334 Dr Brewster’ on the double refraction produced When the three axes A, B, Ovare all equal, the three rec- ‘tangular compressions, produced by the aggregation of the molecules, will destroy one another at every point of the molecule, and the body which they compose will have no ‘double refraction, and cleavages of equal facility. . Hence all crystals in which it is known by cleavage that the particles co- here with equal force in three rectangular directions | have ac- tually no double refraction. If the three attractive axes A, B, Care all che the difference of density which they produce in. the molecules will be related to two axes of double refraction, the strongest ~ of which will be negative or positive according as the compres- sion along C is less or greater than the dilatation produced along C by the united compressions of A and B. Hence all crystals belonging to the prismatic system, in which we are informed by cleavage that the particles cohere with unequal forces in three directions, have invariably two, or, as we have already explained, three unequal axes of double refraction, of which the strongest is sometimes positive and sometimes sind tive, We have supposed the elementary molecules of bodies to be spherical when existing singly, or beyond the sphere of their mutual action; but although their form must, in the case of doubly refracting crystals, be changed into oblate, prolate, or compound spheroids, yet the deviation of these spheroids from the sphere may be so small, that the forms of the bodies which they compose may be regarded as arising from the union of spherical molecules. It is more probable, however, that the form of the molecules suffers a considerable change, and we may consider that change as determining the exact. primitive form of the crystal and the inclination of its planes. The circumstance of almost all rhombohedral crystals hav- ing negative double refraction, which can only be produced by axes of compression in the equator of a prolate spheriod, ex- cludes the supposition, that the. ultimate molecules are spheri- cal particles converted by the forces which unite them into those oblate and prolate spheroids, by means of which, ac- cording to the views of Huygens, all the varieties of rhombo- | by pressure in the molecules of boaies. 335 hedrons may be formed ;* for if this were the case, the obtuse rhombohedrons should possess one positive axis; and the acute ones one negative axis of double refraction. We are constrained therefore to suppose that in rhombohedral crystals the molecules have the form of an oblate spheroid, with its axes so related, that the change superinduced upon it by the forces of aggregation determines the exact form of the com- bination. In carbonate of lime for example, where the pre- cise inclination of the faces of the rhombohedron can be pro- duced only by oblate spheroids whose polar is to their equa- torial axis, as 1 to 2.8204, we may suppose that the spheroids were originally more oblate, and that the forces by which they receive the doubly refracting structure dilated them in the direction of the smaller axis, so as to produce a spheroid having its axis as 1 to 2.8204. Hence if we could suppose the molecules placed together without any forces which would alter their form, they would compose a rhombohedron with a greater angle and having no double refraction. But when they are combined by the attractive forces of crystallization, they compose a rhombohedron: of 105°, possessing negative double refraction. _ In this view of the subject, the form of the ultimate mole- cules of crystals existing separately, may be regarded as de- termining, within certain limits, the primitive form to which they belong; while the doubly refracting structure and the precise form of the crystal are simultaneously produced by the action of the forces of aggregation. | These views receive a remarkable illustration from a new doubly refracting structure, which I discovered many years ago in chabasie, and which will form the subject of a separate communication. In certain specimens of this mineral, the molecules compose a regular central crystal, developing the phenomena of regular double refraction; but in consequence of some change in the state of the solution, the molecules not only begin to form a hemitrope crystal on all the sides of the central nucleus, but each successive stratum has an inferior * See Huygens’s T'raife de la Lumiére, chap. v. and the Edinburgh Journal of Science, No. xviii. pp. 311, 314. 336 Dr Brewster on the double refraction produced doubly refracting force till it wholly disappears. Beyond this limit it reappears with an opposite character, and gradually increases till the crystal is complete. In this case the relative intensities of the axes or poles from which the forces of aggre- gation emanate, have been gradually changed, probably by the introduction of some minute matter, which chemical ana- lysis may be unable to detect. If we suppose these axes'té be free; and the foreign particles to be introduced, so as to _ weaken the force of aggregation of the greater axis, then the doubly refracting force will gradually diminish with the inten- sity of this axis, till it disappears, when the three axes are re- duced to equality. By continuing to diminish the foree of the third axis, the doubly refracting force will reappear with an opposite character, exactly as it does in the chabasie anne consideration. i ane From the mutual dependence of the forces of aggregation and double refraction, it is easy to understand the influence which heat produces on the doubly refracting structure, as exhibited in the phenomena discovered by M. Mitscherlich in sulphate of lime and calcareous spar, and in those which I de- tected in glauberite.* This eminent philosopher has found, by direct experiment, that heat expands a rhomb of ealeare- ous spar in the direction of its axis, and contracts it in diree- tions at right angles to that axis; + that the rhomb thus’be- comes less obtuse, approaching to the cubical forms which have three equal axes, and that its double refraction diminishes. All these effects are the necessary consequences of the preced- ng views. ‘The expansion in the direction of the axis, and * See Edinburgh Transactions, vol. xi. of | + It follows from this fact, that massive carbonate of lime, i in ise the axes of the molecules have every possible direction, should neither expand nor contract by heat, and. would therefore form an invariable pendulum. As there must be, in any given length of massive carbonate of lime, as _ many expanding as there are contracting axes, then, if the contractions and expansions in. each individual crystal are equal, they will destroy one another ; but if they are proportional to their lengths, the contrac ions will cabed the dilatations. In this case, we have only to combine the mar- ble with an ordinary expanding substance, to have an invariable pendulum. The balances of chronometers might be thus made of mineral bodies. Mr Reid’s ‘aeperiments of Candle Wicks. ° 337, the contraction of all the equatorial diameters’ diminish the compression of the axes of the oblate spheroidal molecules, and must therefore diminish its double refraction, as well as the inclination of the faces of the rhomb. In like manner it will be found that in sulphate of lime and glauberite the ex- pansions and contractions will be so related to the three axes, as to explain the conversion of the biaxal into the uniaxal structure, and the subsequent reappearance of the biaxal struc- ture in a plane at right angles to that in which the axes are. found at ordinary temperatures. The phenomena exhibited by fluids under the thane of heat and pressure, and those of doubly refracting crystals, ex-. posed to compressing or dilating forces, are in perfect confor. mity with the above views; so that even without: the funda- mental experiment described in this paper, we might have: been entitled to conclude that the forces of double refraction. are not resident in the molecules themselves, but are the im- mediate result of those mechanical forces by which these mole. cules constitute solid bodies. | ALEeRzLy, October 5th, 1829. Art. XX.—Ezperiments of Candle Wicks.* By Mr J oHN Reip, Member of the South African Institution. Tur fat of the sheep or the cow when exposed to the tempe- rature of 120° of Fahrenheit melts, and when exposed to the temperature of 500° suffers decomposition, and is converted into gaseous compounds consisting of carbon, hydrogen, and oxygen. At this elevated temperature they burn in contact with atmospheric air, the combination being attended with ie extrication of caloric and light. When a candle is lighted a portion of tallow is melted, is attracted by the wick till it is brought within reach of the flame, where it is converted into the compounds above-men- tioned, which, combining with the oxygen of the atmiosphere? +s Read at the South African Institution, and taken from the South. African Quarterly Journal, No. ii. p. 121. NEW SERIES, VOL. III. NO. II. ocTOBEk 1830. Y 338 Mr Reid’s Ewperiments of Candle Wicks. give out caloric and light. ‘This @aloric melts another portion’ of tallow, which is attracted, decomposed, and undergoes com- bustion, and thus is a regular supply kept up. Combustion requires an elevated temperature ; if therefiel any substance at a low temperature is brought near the flame, it abstracts a portion of caloric, and causes a diminution of its size, and.if brought. still more close, or a substance at a lower temperature is made to approach it equally near, it is entirely extinguished. in These circumstances serve the important purpose of regu- lating the combustion, for if this communication of caloric to surrounding objects did not take place, and if the combination was effected at a low temperature, the whole mass would suf- fer almost instantaneous conflagration. When a candle is lighted or relighted, the wick either having no tallow, or only a small quantity, is soon consumed, and the flame is forced to descend till it comes near the mass of unmelted matter; in this case, or when the wick is snuffed too close, the caloric being abstracted too rapidly, the flame is diminished in size; and on account of its proximity to the mass, melts a greater quan- tity of tallow than is required for the proper supply, which accumulates and makes the candle gutter, causing waste and inconvenience. On the other hand, when a candle has burnt for some time, the wick becomes too long, diminishing by its presence the quantity of light evoWed by the combustion: This obscuration may be partly owing to the shadow of this: opaque body, but is in part owing also to the influence it exerts upon the chemical process which takes place. As the wick is not consumed, it requires a constant supply of caloric to keep it at an elevated temperature, which being abstracted from the combustible compounds lowers their temperature, renders the combustion less complete, and produces a yellow flame instead of the usual white flame which diffuses more light. In consequence of this imperfect combustion, a por- : tion of carbon is deposited, which either passes off in the form of smoke, or adheres to the wick increasing its size. It is therefore of importance that the wick should be of a proper length, that it may on the one hand afford sufficient surface upon which combustion may take place, and on the other not Mr Reid’s Experiments of Candle Wicks. 339 diminish more than is necessary the effect of the light which the combustion renders sensible. | The thickness of the wick is of importance as well as its length. When not sufficiently thick it is apt to incline down- wards and fall upon the candle; or if it remain upright it does not attract a sufficient supply of melted tallow for the combustion: when it is too thick, though a sufficient quantity of melted tallow may be attracted and consumed, the illumi- nating effect is diminished in the same way as when it is too long, the diminution being greater in proportion to its size. To remedy this it was suggested to me to try the effect of a flat wick ; accordingly I made a candle with a wick con- sisting of three separate cords placed in a plane with each other, the breadth of which consequently exceeded its thick- ness ; I also made another candle with two wicks placed at a distance from each other, each wick containing five threads ; a third with three wicks each, containing five threads; and a fourth with one round wick, containing twenty threads, and compared the illuminating effect of each with that of a com- mon wax candle. The manner in which the experiment was made was the following: Two square boxes were procured, each having one side open, the top and bottom being closed, these were placed with the open sides facmg a wall; in one I placed the wax candle, in the other box each of the other candles successively, and between the two boxes a cylindrical object at the distance of four inches from the wall; both candles being lighted and snuffed so as to. have the wicks of the length best adapted for giving the maximum of light. Keeping the wax candle at the distance of 18 inches from the wall, the others were moved backwards or forwards ac- cording to circumstances, so as to obtain a shadow of equal intensity from each candle. The following are the results which I obtained, but which, considering that the flame of a candle is at all times variable, can only be looked upon as ap- proximations to the average effect. As the number 18 indi- cates the distance in inches at which the wax candle was placed from-the wall, so the number opposite each of the other candles shows the distance at which they severally produced a light equal to that from the wax candle. 340 Mr Reid’s Eaperiments of Candle Wicks. . : Common wax, i, a ; 18 Tallow with flat wick composed of three cords, each | containing 5 threads, he a 17 Tallow with one wick, containing 20 hobbit 15 Tallow with two wicks, each containing 5 threads, 18 © Tallow with three wicks, each containing 5 threads, 264. It has been ascertained by experiment, that the luminous effect is increased or diminished in proportion to the square of the distance; therefore, if one body produces the same — effect at the distance of sixteen inches as another at twelve inches, the illuminating power is as nine to sixteen. ‘This principle enables us to find out the comparative quantity of light emitted from each of these candles. But for our present purpose it is sufficient to say, that the candle with three wicks, containing in all fifteen threads, produces in burning the same effect at the distance of 26} inches as that with two wicks, containing in both ten threads at the distance of 18 inches, and the same as that with one wick, containing twenty threads at the distance of 15 inches, and so with regard to the others. | In endeavouring. to ascertain the effect produced by dimi- nishing the size of the wick, using as before a wax candle as the standard, I obtained the following results : Wax, - - - . ~ 18 - Tallow with three wicks, each containing 5 threads, 163 Ditto, ditto, ditto, 4 threads, 23% Ditto, ditto, ditto, 3 threads, 213 A circumstance which influences the illuminating effect, is the distance at which the wicks are apart from each other, as it increases till they are at the distance of a quarter of an inch, beyond which wlien five threads compose the wick, two flames are forined, but does not materially diminish at a distance of one-third of an inch, when the flames are completely separate. The most eligible distance would be a quarter of an inch, but as in burning they sometimes vary their position, approaching to or receding from each other, the distance of one-sixth of an inch is to be preferred, at which we may always obtain one flame from both. 4 Mr Reid’s Eaperiments of Candle Wicks. 341 .On endeavouring to ascertain the comparative quantity of light evolved from a given quantity of tallow, using a common tallow candle and one with two wicks, I found that when both are kept snuffed closely, there is but little difference ; in one experiment the quantity of tallow consumed in half an hour, care being taken during the time to keep the ‘flame in each equal, being of the . : Common tallow candle, | te 68 grs. Candle with two wicks, - 66 grs. In another experiment the quantity consumed was the same in each. In another experiment I allowed both candles to burn without snuffing them, till the wick attained the length of an inch, in which state the consumption of tallow is not much different to that which takes place when they are kept of a moderate length. The result I obtained was as follows - Inches. Wax candle as before, - 7 » 18 ‘Tallow with two wicks, each containing 8 threads, when kept snuffed, - $ - 212 Allowing it to remain unsnuffed, - - 195 Common tallow candle with one wick, containing 20 threads, when kept snuffed, + - 15 Allowing it to remain unsnuffed, - - 1c As these observations show that a candle with two wicks gives a light nearly equal to that of a wax candle, I shall en- deavour to point out some of those circumstances which re- quire attention in attempting to make it available for useful purposes. When each thread is not twisted separately, but the different threads are twisted together, each wick in burn- ing constantly changes its position, as occurs frequently in a spermaceti or wax candle, where the end of the wick points sometimes in one direction, sometimes in another, therefore the two wicks at one time recede from and at another approach towards each other, or bend on different sides laterally ; but when each thread is twisted separately, and the whole are then twisted together, strength is given to the wick, and it remains more steadily in one position. A certain number of threads is necessary for giving that strength which is required to keep the wick from bending. Though a sufficient degree of light may be obtained from two B42 Mr Reid’s Ewperiments of Candle Wicks: wicks, each consisting of six or eWen three or four threads, such wicks becoming during the combustion soaked with melted tallow, and the top becoming loaded with a deposit of carbon soon bend, and the rays of caloric being directed too -much upon the candle, melt the tallow too fast, causing it to waste. The wick therefore requires not less than 8 threads, the strength of which is sufficient to keep it upright till it’ reach the required length, when it bends and the extremity is gradually burnt off. * The extremity of the wick of a common tallow caeiddat in burning, continues in the centre of the flame beyond the proper time, and receives such a deposit of carbon as to increase its size greatly, and hence the light becomes di- minished at least one-half, This has been obviated in some’ measure by placing the candle in a position inclining from the perpendicular. But as the angle of inclination necessary to obviate the inconvenience is not less than 30° the sugges-— tion has been seldom adopted. One principal object I had in view in making the experiment now detailed, was to form a tallow candle, so that this advantage might be obtained more readily. As a tallow candle with two wicks gives nearly the same light as a wax candle, it seems better fitted for accomplish- ing this end than one with three wicks; it was with it there- fore that my observations were made. J found that when placed exactly upright, sometimes the wicks either did not bend’ sufficiently soon, or inclined in opposite directions with regard to each other, and assumed a shape which was unpleasant to the eye. It seemed necessary on that account to give the . candle a position somewhat inclined, and I found that an angle of not more than ten degrees was sufficient, the wicks being placed in a plane with each other, and I generally in lighting the candle gave it first a slight bend. With these arrangements I partially succeeded, such a candle’ placed in this manner, burning without requiring - snuffing, and the wicks when consisting of 8 or 10 threads possessing sufficient strength to retain a straight form tll they acquire sufficient length, when the extremity bends and is consumed. | More * The cotton which I used was that sold in the shops for making the best mould tallow candles; 8 threads form a wick about the thickness of that of a common wax candle, - _ Mr Lyell’s Principles of Geology. 343 extensive and varied observations than I have been able to make are necessary to ascertain the comparative advantages and disadvantages which such a tallow candle possesses, com- pared with a common tallow candle, so as to render it fit or unfit for use under peculiar circumstances. I apprehend, however, that though it may answer perfectly well when used in cold and temperate weather, and when there is no wind to affect the direction of the flame; in hot weather or when the atmosphere is not still, it will be found apt to gutter; for, on account of circumstances which further investigations are re- quired to explain satisfactorily, tallow is very liable, particu- larly in warm weather, to melt in too large quantity at the surface and to run down the sides of the candle. - Art. XXI—ANALYSIS OF SCIENTIFIC BOOKS AND ME- MOIRS. I.—Principles of Geology, being an attempt to explain the former changes of the Earth's Surface by reference to causes now in operation. By CHARLES Lye L, Esq. F. R. S. Foreign Secretary to the Geological Society. In two volumes. Vol. I. London, 1830. Pp. xv. and 511. Unsett ep as is the present state of geology, and prudent as may be the line most generally adopted in Britain since the establishment of the Geo- logical Society, of publishing researches upon individual classes of pheno- mena, rather than forming large and imperfect attempts at complete sys- tems, we are not sorry to see an effort to embody the multifarious facts, which, during a long period, have been accumulating in the annually in- creasing piles of Transactions and periodical works ; more especially when undertaken by a man of the scientific character of Mr Lyell, and in the responsible situation which he holds. For some years, no work affecting to be a complete geological manual (for we rather look upon the volume before us as a judicious compilation, than as a work of much originality, ) has issued from the British press, unless we should except one of recent date and of unbounded pretensions, which has been characterized by a distin- guished president of the Geological Society of London as a work ‘‘ in which the worst violations of philosophic rule, by the daring union of things in- congruous, have been adopted by the author from others, and at the same time decorated by new fantasies of his own.” Some better specimen of British talent was therefore desirable to do away the unfavourable impres- sion which might still attach to the national scientific character, even after the misty light shed by the ‘* New System” in some corners of the speculative world had been finally extinguished by the anathema of one of the first authorities in Europe. 344 Analysis of Scientific Books and Memoirs. We turn, therefore, with pleasure to a work having the recommendations of great sound sense, industry in eaten, and a pleasing and generally perspicuous style in execution. We are, however, of opinion that it ought not to have appeared without the second volume ; which, indeed, we can hardly suppose will be sufficient to contain the reninindiee of this most ex- tensive subject on the same scale of fulness of illustration with the bulky introductory one before us. Mr Lyell’s arrangement also appears to us a faulty one. Geology is a science which ought to be, and in fact must even- tually be, treated analytically. Mr L. attempts to treat it synthetically, and the greater part of this volume is occupied, after assuming an hypothe- sis, with collecting data and postulates for constructing his propositions ; and almost the whole application to phenomena is left to the latter portion of his work. He ought first to have described the features of the crust of the globe, and from the natural facts they present, deduced the probability of one assumption in preference to all others; then developing the results of this hypothesis, descended again to phenomena, and proved the agree- ment which he asserts. Now in this first volume, he prevents the reader (unless he be previously acquainted with the subject) from doing any thing but following him ; he treats opinions with which he does not agree as un founded dogmas, and directs the mind almost exclusively to those facts which bear upon his particular views ; indeed, how could he do otherwise, unless by stating at the commencement the actual appearances of the crust of the earth, unconnected with any theory whatever? But this would be the analytical method. The other principal fault which we consider runs through the work, and is connected with the former, is an appearance of prepossession in favour of a theory almost unavoidable from the arrange~ ment adopted, which induces him to dwell quite disproportionately upon effects confirmatory of his system, and to pass lightly over its difficulties ; which are-intended, we presume, to be stated more fully in order to refuta- tiow, in the ensuing volume. The arrangement of Mr Lyell’s plan, so far as it is contained in the present portion of his work, appears to be the following :—After stating the objects of the legitimate science of geology, he gives a rapid sketch of its history, and then, in a chapter on the causes which have retarded its pro-, gress, brings forward his assumption, which the remainder of the work is intended to prove, that causes at present in operation are sufficient to ac- count for the whole phenomena of structure observable in the strata of our globe, provided sufficient time be allowed. Foreseeing that the testimony of organic remains, so strongly indicative of a change of climate since the larger part of the crust of the earth was deposited, would be most apt to occur as a contradiction to his hypothesis, he dips into the chapter of phenomena, and selects this, and this alone, for confutation. He endea- vours to prove that the change of climate is referrible to causes at present active. He then assaults the argument which the proofs of the former ob- jection raised up, that the types of organization in the animal and vege- table kingdom have distinctly and undeniably changed ; and here again from his mode of arrangement, his argument on this important subject is left incomplete, and the greater part of it deferred to another portion of the Mr Lyell’s Principles of Geology. 345 work. He throws down at once, with an abruptness little short of the ez. cathedré. fiat, the entire theory of the progressive advancement in organiza- tion of fossil remains, as we ascend through the strata from the older deposits to the uppermost or latest, and thence infers, that no change in the laws of nature can be argued from a mere change in the species which now inhabit the waters and the land. Finally, he denies any argument; derived from the recent appearance of man, which he reconciles to the hypothesis, by calling in the aid of metaphysical reasoning, now rather an exploded instrument in geological inquiry. Mr Lyell next divides the changes at present going forward, as they affect the organic and inor- ganic world; and the remainder of the volume is occupied by the con- sideration of the latter, which he divides into aqueous and igneous, the discussion of which forms, we think, by much the happiest part of the work, and, if placed in rather too prominent a view, is a least both instruc- tive and interesting. After this general outline of the contents of the volume, we shall pro- ceed to notice some parts of it more particularly, and make several extracts. The limits to which we chance to be confined in this Number, will not permit us to do more than commence our remarks, which will be conclud- ed in a second notice in our ensuing Number. We shall not enter upon the subject of the history of geology, contained in the first chapter of the work: We will only say that Mr Lyell appears: in some instances to have allowed his theoretical opinions to detract too much from the real merits of his opponents, and perhaps is too solicitous to gather from the loose speculations of older geologists, the germs of all that does most honour to the modern progress of the science. It would be strange, if among vast masses of hypothetical errors, were not to be found some guesses at truth; and we have only to consult the ingenious works of Dutens, to see how easy it is to assert plausibly, that Newton, Locke, and Galileo, were only plagiarists from Pythagoras, Aristotle, and Ptolemy. Mr Lyell supports, on the whole, the Huttonian theory, though he will not admit the introduction of new agents, or even the greater magni- tude of existing ones in the formation of the strata, and gives to his pre- decessors much of the merit usually assigned to Hutton. The progress of geology of late years is next duly noticed, though perhaps the following is hardly an impartial picture of its present state. << When we compare the result of observations in the last thirty years with those of the three preceding centuries, we cannot but look forward with the most sanguine expectations to the degree of excellence to which geology may be carried, even by the labours of the present generation. Never, perhaps, did any science, with the exception of astronomy, unfold, in an equally brief period, so many novel and unexpected truths, and overturn so many preconceived opinions. The senses had for ages declar- ed the earth to be at rest, until the astronomer taught that it was carried through space with inconceivable rapidity. In like manner was the sur- face of this planet regarded as having remained unaltered since its creation, until the geologist proved that it had been the theatre of reiterated change, and was still the subject of slow but never ending fluctuations. The dis- 346 Analysis of Scientific Books and Memoirs. © covery of other sytems in the boundless #egions of space was the triumph: of astronomy—to trace the same system through various transformations—. to behold it at successive eras adorned with different hills and valleys, lakes and seas, and peopled with new inhabitants, was the delightful meed — of geological research. By the geometer were measured the regions of space, and the relative distances of the heavenly bodies—by the geologist myriads of ages were reckoned, not by arithmetical computation, but by a train of physical events—a succession of phenomena in the animate and inanimate worlds—signs which convey to our minds more definite ideas. than figures can do, of the immensity of time.” P. 73. - Perhaps the science was never more unsettled than at this moment, but, _ it is in that species of confusion which betokens the resolution to lay. the foundations of it on a firmer basis, and so far it bears a promising as- pect; yet year after year we see propositions, once considered the most un= doubted, confuted by the progress of careful research, and we are some= times almost tempted to doubt the existence of fixed principles at all. But the time has passed when genuine philosophers are content to gloss over obstinate facts in order to obtain a short cut to ultimate conclusions, — and the volumes of the Geological Transactions contain a mass of laborious= ly gleaned facts, which, however contradictory or perplexing they may often appear, will at last, we may hope, settle down into a firm basis for. a superstructure to be raised by strict induction. Be it ever remembered, that the anomalies which seemed to threaten the very existence of the New= tonian system of the universe, finally supported it by the most irrefraga~ ble of all testimony. | In discussing causes which have retarded the progress of the science, Mr Lyell considers the reluctance to admit a sufficiently long tract of time, for the accomplishment of geological revolutions, the greatest. The fol- lowing is one of the most plausible points of view in which he placed this fundamental opinion. mi « One consequence of undervaluing greatly the quantity of past time. is the apparent coincidence which it occasions of events necessarily dis~ connected, or which are so unusual, that it would be inconsistent with all calculation of chances to suppose them to happen at one and the same» time. When the unlooked for association of such rare phenomena is wit- nessed in the present course of nature, it scarcely ever fails to excite a suspicion of the preternatural in those minds which are not firmly con- _ vinced of the uniform agency of secondary causes ;-—as if the death of some individual in whose fate they are interested, happens to be accom- panied by the appearance of a luminous meteor, or a comet, or the: shock of an earthquake. It would be only necessary to multiply such coincidences indefinitely, and the mind of every philosopher would be dis- _ turbed. Now it would be difficult to exaggerate the number of physical’ events, many of them most rare and unconnected in their nature, which were imagined by the Woodwardian hypothesis to have happened in the course of a few months; and numerous other examples might be found of popular geological theories, which require us to imagine that a long succession of events happened ina brief and almost momentary period.” P.80- | Mr Lyell’s Principles of Geology. 347 Here our author, seeing the difficulties which must be opposed to his idea of the formation of strata by mere aqueous degradation, brings in the undeniable fact of the uniformity of arrangement in the strata of the whole globe, (of which, however, he has yet given no exposition, without which the reader ought to be supposed ignorant of the fact ;) and proceeds to rid himself of this difficulty. ** When it was imagined that sedimentary mixtures, including animal and vegetable remains, and evidently formed in the beds of ancient seas, were of homogeneous nature throughout a whole hemisphere, or even far- ther, the dogma precluded at once all hope of recognizing the slightest analogy between the ancient and modern causes of decay and reproduc- tion. For we know that existing rivers carry down from different moun- tain-chains sediment of distinct colours and composition ; where the chains are near the sea, coarse sand and gravel is swept in; where they are distant, the finest mud. We know, also, that the matter introduced by springs into lakes and seas is very diversified in mineral composition ; in short, contemporaneous strata now in the progress of formation are greatly varied in their composition, and could never afford formations of homogeneous mineral ingredients co-extensive with the greater part of the earth’s surface. This theory, however, is as inapplicable to the effects of those operations to which the formation of the earth’s crust is due, as to the effects of existing causes. The first investigators of sedimentary rocks had never reflected on the great areas occupied’ by modern deltas of large rivers ; still less on the much greater areas over which marine currents, preying alike on river-deltas, and continuous lines of sea-coast, might be diffusing homogeneous mixtures. They were ignorant of the vast spaces ever which calcareous and other mineral springs abound upon the land and in the sea, especially in and near volcanic regions, and of the quantity of matter discharged by them. When, therefore, they ascertained the ex tent of the geographical distribution of certain groups of ancient strata— when they traced them continuously from one extremity of Europe to the other, and found them flanking, throughout their entire range, great mountain-chains, they were astonished at so unexpected a discovery ; and, considering themselves at liberty to disregard all modern analogy, they in- dulged in the sweeping generalization, that the law of continuity prevailed throughout strata of contemporaneous origin over the whole planet. The — difficulty of dissipating this delusion was extreme, because some rocks, formed under similar circumstances at different epochs, present the same external characters, and often the same internal composition ; and all these were assumed to be contemporaneous until the contrary could be shown, which, in the absence of evidence derived from direct superposi- tion, and in the scarcity of organic remains, was often impossible.’—Pp. 90, 91. Here Mr Lyell seems fairly to entrench himself in his deltas and defy at- tack, and while he enlarges on the great absolute magnitude of these modern deposits, upon which, as we shall afterwards see, he collects many inte- resting particulars, he forgets, and would have the reader forget, their re- lative insignificance when compared to the continental masses which he con- ceives to have had a similar formation ;—so insignificant indeed that none 348 Analysis of Scientific Books and Memoirs. of them are more than specks in the Map of the world, and yet these are the produce of the continued action of 6000 years. We know not whether it is boldest to call into the aid of a theory, powers of mechanical action greatly surpassing those at present witnessed in the economy of: nature, or periods of time almost transcending our powers of conception ; our au- thor seems to think the latter no assumption at all, and the former an un- warrantable one ; but we do not see this difference, and we are much dis- posed to agree with those distinguished writers who consider the former hypothesis, when applied to conformations, so universal as the superposi- tion of rocks, at least as plausible as the latter. In the sixth chapter Mr Lyell proceeds to prove that a change of climate has taken place in high latitudes, by a reduction of temperature, since the older strata were deposited,—a position so generally, (though not universal- ly,) admitted, that we shall not dwell upon it. In the succeeding chap- ters he attempts to show that such a change might be accounted for on simply physical principles. Considerable details are entered into to show that the existence of land, and especially high land, in northern latitudes, tends to the refrigeration of the zones betwixt them and the equator,—a fact sufficiently illustrated by the great decrement of temperature in the vast tracts of North America and Siberia, below that of the corresponding latitudes in Europe and other countries, where an equilibrium is assisted by the maritime situation ; therefore it is conceived that the amount of land in high latitudes. is the proper index to the climate. ‘* It next re- mains for us,” says Mr Lyell, “ to inquire whether the alterations which the geologist can prove to have actually taken place at former periods in the northern hemisphere, coincide in their nature, and the time of their occurrence, with such revolutions in climate as would naturally have fol« lowed, according to the meteorological principles already explained.” It is impossible for us to follow Mr Lyell through this rather intricate chap- ter, or to point out what we consider the weak points of his argument, but we will give some of his deductions in his own words. ‘‘ We may ob- serve, that although geologists have neglected to point out the relation of changes in the configuration of the earth’s surface with fluctuations in general temperature, they do not dispute the fact, that the sea covered the regions where a great part of’ the land in Europe is now placed, until after the period when the newer groups of secondary rocks were formed. There is, therefore, confessedly a marked coincidence in point of time between the greatest alteration in climate and the principal revolution in the phy- sical geography of the northern hemisphere. It is very probable that the abruptness of the transition from the organic remains of the secondary to those of the tertiary epoch, may not be wholly ascribable to the present de- ficiency of our information. We shall doubtless hereafter discover many intermediate gradations, (and one of these may be recognized in the calca- reous beds of Maestricht,) by which a passage was effected from one state of things to another ; but it is not impossible that the interval between the chalk and tertiary formations constituted an era in the earth’s history, when the passage from one class of organic beings to another was, com- paratively speaking, rapid. For if the doctrines explained by us in regard to vicissitudes of temperature are sound, it will follow that changes of Henry’s Elements of Experimental Chemistry. 349, equal magnitude in the geographical features of the globe, may at different periods produce very unequal effects on climate, and, so far as the exist- ence of certain animals and plants depends on climate, the duration of spe- cies may often be shortened or protracted, according to the rate at which the change in temperature proceeded.”—P. 139. It is, however, impossible not to remark, that, notwithstanding the manifold elevations which appear to have taken place between the deposition of the mountain limestone and the Maestricht deposit above chalk, the corallines of the one, and the fos- sil turtles of the other, point equally to a tropical temperature. The change in the conformation of organic remains, as indicative of temperature, seems abrupt, and confined to the newest formations.* How far Mr Lyell’s deductions on this curious subject may be adopted by geologists we are doubtful, but they deserve the credit of being striking and ingenious spe- culations. In our next Number we shall meet Mr Lyell on less debateable ground, and hope tomake more extended and popular extracts from his interesting volume. Il.—The Elements of Experimental Chemistry. By Witt1am Henry, M. D., F. B.S. &c. &c. The Eleventh Edition, comprehending all the recent Discoveries, &c. In two Volumes. I.ondon, 1829. With plates and Engravings on Wood. From this new edition of Dr Henry’s system of chemistry, we extract the following recommendation, which is addressed to the notice of learned Societies. ‘‘ The great laws of combination in definite and in multiple pro- portions, on which the Atomic THeory mainly rests, have, more especi- ally, derived increased support from the accumulated mass of evidence. In too many instances, it must be acknowledged, we have not, even yet, attained all the precision that is desirable, as to the true proportions in which bodies combine. Nor can we arrive at this degree of certainty, un- til the relative weights of some of the elementary gases have been deter- mined, with the aid of the most refined instruments, and with the most elaborate and scrupulous correctness. It were to be wished, indeed, that this should be attempted under the auspices of some one of those learned societies, which have been instituted for the promotion of science ; and that the investigation should be confided to a commission of its members, whose skill, experience, and fidelity, would be a pledge for the accuracy of the re- sults. The preciseadmeasurement of an arc of the meridian was not more important to astronomical truth, than the exact determination of the spe- cific gravities of the elementary gases is to chemical philosophy.” With the importance of the foregoing observation we concur ; and should be proud if the chief philosophical institution of our Scottish metropolis would take the lead in putting into execution so desirable an object. In the preface, the author has alluded to the deep loss which the scien- tific world has sustained by the death of Sir Humphry Davy and Dr Wol- laston, in a joint eulogium upon these two distinguished philosophers, which is characterized no less by its just discrimination of their respective excellencies, than by its forcible eloquence: ‘‘ It is impossible” says Dr Henry - © Of this Mr Lyell has himself furnished evidence in reference to some of the Subapennine formations in his Sixth Chapter. 350. Analysis of Scientific Books and Memoirs. “ to direct our views to the future imptovement of this wide field of science, without deeply lamenting the privation, which we have lately sustained, of two of its most successful cultivators, Sir Humphry Davy and Dr Wollas- ton,—at a period of life, too, when it seemed reasonable to have expected, from each of them, a much longer continuance of his invaluable labours, — To those high gifts of nature, which are the characteristics of genius, and which constitute its very essence, both those eminent men united an un- wearied industry and zeal, and research, and habits of accurate reasoning; without which even the energies of genius are inadequate to the achieve« ment of great scientific designs. With these excellencies, common to both, — they were nevertheless distinguishable by marked intellectual peculiarities. Bold, ardent, and enthusiastic, Davy soared to greater heights ; he com- manded a wider horizon; and his keen vision ‘penetrated to its utmost boundaries. His imagination, in the highest degree fertile and inventive, took a rapid and extensive range in pursuit of conjectural analogies, which he submitted to close and patient comparison with known facts, and tried by an appeal to ingenious and conclusive experiments. He was imbued with the spirit, and was a master in the practice, of the inductive logie ; , and he has left us some of the noblest examples of the efficacy of that great instrument of human reason in the discovery of truth. He applied it, not only to connect classes of facts of more limited extent and importance, but to develope great and comprehensive laws, which embrace phenomena, that are almost universal to the natural world. In explaining those laws, he cast upon them the illumination of his own clear and vivid conceptions ;— he felt an intense admiration of the beauty, order, and harmony, which are conspicuous in the perfect Cuemistry or Nature ;—and he expressed those feelings with a force of eloquence, which could issue only from a mind of the highest powers, and of the finest sensibilities. With much less enthusiasm from temperament, Dr Wollaston was endowed with bodi- ly senses of extraordinary acuteness and accuracy, and with great general vigour of understanding. ‘Trained in the discipline of the exact sciences, he had acquired a powerful command over his attention, and had habitu- ated himself to the most rigid correctness, both of thought and of language. He was sufficiently provided with the resources of the mathematics, to be en= abled to pursue, with success, profound enquiries in mechanical and optical philosophy, the results of which enabled him to unfold the causes of phe- nomena, not before understood, and to enrich the arts, connected with those sciences, by the invention of ingenious and valuable instruments. In Cuz- mistTry, he was distinguished by the extreme nicety and delicacy of his observations ; by the quickness and precision, with which he marked re- semblances and discriminated differences; the sagacity with which he de- vised experiments, and anticipated their results ; and the skill, with which he executed the analysis of fragments of new substances, often so minute as to be scarcely perceptible by ordinary eyes. He was remarkable, too, for the caution, with which he advanced from facts to general conclusions; a caution which, if it sometimes prevented him from reaching at once to the most sublime truths, yet rendered every step of his ascent a secure sta- tion, from which it was easy to rise to higher.and more enlarged inductions. 7 Royal Society of Edinburgh. 351 Thus these illustrious men, though differing essentially in their natural powers and acquired habits, and moving, independently of each other, in different paths, contributed to accomplish the same great ends—the evolv- ing new elements ; the combining matter into new forms ; the increase of human happiness by the improvement of the arts of civilized life; and the establishment of general laws, that will serve to guide other philosophers onwards, through vast and unexplored regions of scientific discovery.” The foregoing interesting extracts from the new edition of Dr Henry’s ‘chemistry are sufficient. To enter into an analysis of such a well known standard work as this, proceeding from the pen of one who ranks among the most eminent chemical philosophers of the day, would indeed be a su- perfluous task. We remember many years ago, in a very different chemi- cal era to the present, when the first edition of this work appeared under the unpretending form of a duodecimo volume, intended as a manual for the experimental student. From this time, Dr Henry has been an unre- mitting labourer in the field of science, and as his work in its successive editions has kept a regular pace with the advances of chemical knowledge, to which he has himself been so distinguished a contributor, the eleventh edition now appears before the public in a very enlarged and ample form, containing a store of information, the selection and arrangement of which cannot be too highly rated. In short, Dr Henry is to he esteemed as an author, who has always been an industrious collector of facts, and an accurate reasoner; avoiding premature speculations, and strenu- ous for the rigid canons of inductive philosophy. For this reason, his vo- lumes may be recommended as among the most useful and the safest which can be entrusted to the hands of the student. Art. XXIL—PROCEEDINGS OF SOCIETIES. 1. Proceedings of the Royal Society of Edinburgh. March 15, 1830.—The following communications were read :— 1. Dr Knox concluded the Second Part of his paper on Hermaphroditi- cal Appearances. 2. Dr Christison read a paper entitled, ‘‘ An Experimental Inquiry into certain doubtful points in the Physiology of the Blood and Respiration. Part I: On the Mutual Action of the Blood and Atmospheric Air.” April 5. The following Gentlemen were duly elected Ordinary Mem- bers of the Society :— The Hon. Mounstuart Wiaettndoiul JamMEs SyME, Esq. Tuomas Brown Esq. of Langfine. Dr Grecory read the translation of a paper, entitled, “ On thé Me- chanism by which the Modulation of the Human Voice is affécted in Singing.” By Francisco Bennatt. M. D. of the Universities of Padua and Pavia. April. 19.—The following communications were read :— 352 Proceedings of Societies. 1, Account of observations made in Seotland on the Distribution of dhe Magnetic Intensity, by Mr Dunlop. 2. A notice regarding a method of producing Continuous Motion i in ‘the circumference of a Ellipse, with its application to the construction of an Elliptograph. By Professor Wattacr. An Elliptograph and a ihiteni were exhibited. 2. Finseoedings of the Society for the Encouragement of the Useful Anta s in Scotland. The following communications have been read and exhibited to the Society since 17th Feb. 1830 :— March 3, 1830.—1. A Model and Description of a Cart to be peipliled by levers and cranks, acted on by the weight and force of one inan, without a horse. By Witt1am ALtLan, Morningside. 2. Description of a Slow Motion for the beam compass. By Mr Epwarp Sane, teacher of mathematics, Edinburgh, M. S. A. March 17.—1. An account of the latest improvements in the turning- lathe, including the slide-rest, and apparatus for drill-turning ; as also an account of the planing-engine and apparatus, with engravings. Communi- cated by John Robison, Esq. Sec. R. S. K. and M.S, A. Ys 2 Drawing and description (as amended) of a simple, cheap, and accurate rain-gage. By Matthew Adam, A. M. Rector of the Academy of Inverness and Assoc. S. Arts. See this Vol. p. 53. bite 8. Description of a Pendulum Chronometer, in which the arbors of the wheels move on friction rollers, and the pinion leaves are made so as to re- volve by the impulse of the wheel teeth, which are of a peculiar form, Made by Davip WutreLaw, watch and clock-maker, 16, Prince’s Street. Edinburgh, for the late Andrew Waddell, Esq. Hermitage Hill, Leith. Communicated by the late Mr Waddell. March 31.—1. Observations on the application of heated air to the warming of dwelling-houses and of churches, hospitals, and other public buildings ; with remarks on various kinds of stoves used for this purpose. By Mr Robert Ritchie, ironmonger to his Majesty, High Street, Edin- burgh. Models of the stoves, &c. were exhibited. 2. Description of an improved levelling rod. By Mr Jamzs Fur, civil engineer, Terrace, Edinburgh. The rod was exhibited. 3. Additional observations on safety windows for upper stories of houses. By Thomas Johnston, ink-manufacturer, Glasgow. ‘ ; April. 14.—1. Remarks on the Eidograph, Pentagraph, &c. were read. By Mr Professor Wallace, F. R.S.E.and M.S.A. The instruments were exhibited. 2. Notices of various plans of applying heat, either by common fire places, or by steam apparatus, were communicated by Mr Robert Ritchie, iron- monger to his Majesty, High Street, Edinburgh. Models of various ali &c. and of a drying house were exhibited. 3. Notice of an apparatus for facilitating the making of infusions by hot water, and particularly from coffee. By John Robison, Esq. Sec. R.S. E. and M. §. A. . Cambridge Philosophical Society. 353 George Mackillop, Esq. Ainslie Place, and Mr Adam Wilson, smith, Mint, were admitted Ordinary Members, rotted . April. 28.—1. Notice respecting Mr Cuthbert’s Elliptic Metals for Re- flecting Microscopes. Communicated by Dr Brewster, F. R. §. ‘E, and M.S. A. See this Journal, No. iv. p- 321. Oo 2. Investigation of the Spherical Abberration of a Diamond Lens. By Mr Andrew Pritchard, London, Hon. M. S. A. for Scotland. Communi- cated by Dr Brewster, F. R. S. E. and M.S. A. See No. iv. p. 317, 3. Description of the improvements on the common mortice lock. By Mr James Wituiamson, Melrose, Assoc. Soc. Arts. The Lock was ex- hibited, 4. Description of a method of destroying Vermin on Fruit Trees, Bugs, &c. by means of Steam. By James Grieve copper-smith and brazier, 20 Greenside Place, Edinburgh. The apparatus was exhibited. 5. Notice regarding the improved steam and indicator and oil test. By John M‘Naught, engineer, Glasgow. 6. Memorial on the construction of Chimnies, so as to prevent Smoke. By Alexander Mollison, Englinton Street, Glasgow. ! 0 7. Notice of a Swiss Lock, of neat, simple, and efficient construction, made by Mr Cormack, smith, Chalmers’s Close, for and presented to the ' Society by Sir Atexanper Mutr Mackenzir of Delvine, Bart. The lock was exhibited. ; Sir ALExanpDeR Muir Mackenzie of Delvine, Bart. was addmitted an Ordinary Member. The following donations were laid on the table, viz.— 1. Microscopic illustrations. By C. R. Goring, M, D, and Anprew PritcHarp, Hon. M. Soc. Arts for Scotland ; with Coloured Engravings. Presented to the Society of Arts by Mr Pritchard. ahs 2. Plans for the floating off of stranded vessels, and for raising those that have foundered ; with an improved method of carrying vessels over banks in shallow water. By Joun Ming, teacher of architectural and mechanical drawing, Edinburgh, and Curator Soc. of Arts for Scotland, Presented by the Author. ; | 3 3 Proceedings of the Cambridge Philosophical Society. ° March 22, 1830.—The Rev. Professor Sedgwick, Vice-President in the chair. A notice by Mr Miller of St John’s was read, on the measurements of certain crystals found in the slags of furnaces at Merthyr Tydvil and at Birmingham. The form and angles of these crystals were ascertained to be the same as those of olivine: and agree therefore with those of crystals found by Prof. Mitscherlich in the forges of Sweden and Germany. Mr Coddington gave a further explanation of the construction of: his newly-invented microscope, and of the superiority of its performance, which was shown by a comparison with a large microscope on the usual construc~ tion made by Dollond. See this volume, p. 155. A paper by H. K. Cankrien, Esq. of ‘Trin. Coll. was also read, ‘on the calculus of variations.” kits Ds ae , ? | NEW SERIES, VOL. I1I. NO. II. OCTOBER 1830. 354 Proceedings of Sgcieties. After the meeting; Mr Willis gave an account, illustrated by models and drawings, of the various organs which compose the apparatus of deglutition and vocalisation. He explained in particular the various muscles. of the palate, pharynx, and tongue ; and the forms which these parts assume.in the course of their various functions were exhibited as drawn from actual measurement. Mr Willis further explained the distinction of the parts which are employed in producing the musical note of the voice, and those which determine its vowel quality. April 25.—The Rev. Professor Sedgwick i in the chair. Among other presents laid before the society, was a collection of the eggs of British birds, the gift of Mr Yarrell. _ The Rev. L, Jenyns read 2 communication on the subject of the late severe winter. | The Rev. H. Coddington read a memoir on the imjisct of his improved microscope, which was again exhibited and tried on several of the usual test objects, (striated scales or feathers of different butterflies and moths. ) Professor Whewell made some observations on the proof of the first law of motion. After the meeting, Professor Whewell gave an account of the arguments brought forward by the German writers who reject the Newtonian theory of optics, and of the doctrines on this subject propounded by the celebrated , Goéthe. It has been very common of late years among German writers | to speak of the Newtonian doctrine of the separation of white light into colours by refraction, as of a system which is palpably and even ridiculously false ; retained only through the influence of the most perverse blindness and pre- judice ; and rejected by all persons of philosophic views. A different theory has been maintained by the celebrated Goethe in his ‘* Farben- lehre,” and has met with very considerable success in his own country. The confident and triumphant manner in which the advocates of the new ‘system are in the habit of speaking, is calculated .to excite some :curiosity as to their arguments in the minds of those who have been accustomed to consider the Newtonian principles as established upon an unimpeachable series of inferences from experiment. Goethe has criticised, page by page, a great part of Newton's Opties, and brings against the author charges, which are perpetually repeated by other writers, of mis-stating and misinterpreting his experiments, of con- founding simple and complex phenomena, and even of bad faith. The main argument, however, is, that the asserted separation of white light by ; the prism never takes place except at the boundary of a bright surface ; and that, therefore, darkness as well as light is requisite for the produc- tion of the coloured image. The colours, it is maintained, are always a fringe to the image, and prove no difference of refrangibility in the rays of light. Goethe’s theory of the cause of the coloured borders produced by a prism may be stated as follows: 1° Light seen through a dim transparent medium appears yellow, orange, and red, according to the thickness and transpa- rency of the medium ;—darkness seen through a similar medium, exhibits Natural Philosophy. 355 in a similar suecession, blue and violet tints. 2° When refraction takes place, the principal image is accompanied by an accessory image, (“ neben= bild,”) which is near and similar to the principal image, but is carried farther than that is in the direction of the refraction. 3° This accessory image being but, as it were, half an image, may be looked upon as a dim transparent medium, such as is mentioned in 1°. 4° Hence, at that end of the bright image which is foremost in the direction of the refraction, the accessory image will encroach upon the dark surrounding space, and will produce blue and violet, as in 1°, at the other extremity of the image, the accessory image will be drawn over part of the bright image, and will pro- duce red and yellow. Hence we havea border blue and so forth at one end, and a yellow rim at the other, of a bright object when refracted. 5° The green in the middle of the spectrum is produced by the mixture of the yellow of one end, with the blue of the other, when the image is of such ‘a size as to allow them to coincide. It was not considered necessary to compare the two theories, or to make any remarks on the above arguments against the Newtonian reasonings. May 10.—Dr F. Thackeray, the Treasurer, in the chair. Various addi- tions to the Society’s collection of British birds, presented by the Rev. L. Jenyns, and some specimens of insects, presented by Mr Dale, were laid before the meeting. _ A paper by T. W. Chevalier, Esq. on the Anatomy and Physiology of the Ear, was read. After the meeting, Professor Cumming exhibited and gave an account of, some philosophical instruments which have recently been invented or improved. He described the contrivance proposed by Professor Leslie for measuring the specific gravity of powders ; and pointed out the resemblance between the instrument on this account termed a koniometer, and the ste= reometer invented by M. Suy in 1797. .Prof. Cumming explained also a me- thod of applying a similar process in a more convenient and compendious manner by means of the air-pump. | An account was likewise given of the apparatus of Mr Meikle, for comparing the specific gravities of two Snide 3 and an improvement in its construction pointed out. Professor Cumming exhibited to the members an instrument, the object of which is to measure the total effect of the whole sunshine which occurs in the course of a given day or any other time. Ant. XXIIJ.—SCIENTIFIC INTELLIGENCE. I. NATURAL. PHILOSOFHY. MAGNETISM. 1. On the production of Magnetism by Friction. By M. Hatpat.-— Friction has been long known to be capable of producing magnetism, but it was not supposed to be efficacious, unless upon iron either magnetised or in a neutral state. M.Haldat of Nancy has, however, found that all hard bodies may, by means of friction, assist in the decomposition of the mag- 356 Scientific Intelligence. netic fluid, if their action is promoted by the combined action of magnets, which, by themselves, are incapable of producing it. To prove this, take a piece of soft iron wire, a decimeter. long, (about 4 inches,) and a milli- meter (1-25th uf an inch) in diameter. If this wire is placed horizontally between two bar magnets, with their opposite poles facing one another, and at such a distance that it cannot be magnetised, it will receive distinct magnetism by friction with all hard bodies,such as copper, brass, zinc, glass, hard woods, &c.—Ann. de Chim. tom. xlii. p. 41. Il. CHEMISTRY. 2..Mineral Kermes.—The composition of mineral kermes, as determined by Berzelius and Rose, in accordance with Philips, has lately been called in question by the French chemists. According to the former chemists, it is exactly the same substance as the common native sulphuret of antimony. Robiquet, Buchner, and Henry Junior, who found it to contain oxide of antimony, have been joined by Gay-Lussac, who says, (An. de Chim. et de Phys. xiii. p. 87.) that, when heated with hydrogen gas, it gives off water, and that it is in fact a compound of 1 atom oxide of antimony +2sulphuret of antimony. Rose has therefore repeated his experiments ( Poggendorff’s An-~ nalen, xvii. 324.) with his former results, He prepared his kermes by boil- ing carbonate of soda on the common sulphuret of antimony, filtering, set- ting aside to cool, filtering again in half an hour to collect the precipitate, drying it well on bibulous paper, and afterwards by a gentle heat till it ceased to lose weight. He found the kermes thus prepared to give no water in a current of hydrogen gas, but to leave 72-71 per cent. of metallic anti- mony. His former analysis gave 72.32 per cent., and Berzelius found in the common sulphuret 72.77 per cent. The residual liquid, according to Rose, after some hours, becomes troubled, and deposits a white sediment, being oxide of antimony combined with soda. If the kermes be not filtered soon after its deposition, it will thus be contaminated both with oxide of an- timony and with alkali,—and this is probably the source of the oxide found by the French chemists. Since no carbonic acid is evolved during the pre- paration of the kermes: by this process, all that takes place is a mere solu« tion of the sulphuret of antimony in the carbonated alkalies. 3. Phosphuret of Sulphur.—When the proto-chloride of phosphorus is ex- posed in like manner to the action of sulphuretted hydrogen—heat is evolved, and there is formed a solid yellow substance without any apparent . crystalline form, and adhering strongly to the glass. This is a phosphu- ret of sulphur. At common temperatures it decomposes water, and at length disappears in it, forming sulpharetted hydrogen and phosphoric acid. Its atomic constitution is probably * 2 atoms phosphorus + 3 atoms sulphur. Our readers will remember that Faraday and Mitscherlich have described another compound of these elements, consisting of 2 atoms phosphorus + 1 atom sulphur. * An. de Chim. et de Phys. xlii. p. 25. Chemistry. | 357 4. Chlorides, Iodides, and Bromides of Sodium.—The bromides and io- dides of sodium crystallize from their solutions at common temperatures with water of crystallization—common salt first ata temperature several degrees (14° to 17° Fahr.) below the freezing point. Anhydrous crystals of the _ bromide are obtained from a solution at a temperature of about 86° Fahr. and of the icdide at a temperature from 104° to 122° Fahr. The anhy- drous crystals of these three salts of sodiuna are perfectly alike, being cubes in‘which, though seldom, as is known to be the case with common salt secondary faces, are found. ) Of the three hydrous salts the chloride forms the finest crystals, but the determination of their angles is very difficult, since at a temperature -above 14° Fahr. they deliquesce, and above 32° they lose their water, which, when it has previously become liquid, dissolves a portion of the salt. The crystals of the hydrous bromide is not changed at common temperatures, and can be measured with great ease,—the hydrous iodide, on the contrary, deliquesces, and is very difficult to measure, nevertheless I have succeeded in measuring all of them by the reflecting goniometer. They are all isomorphous, and the angles differ from each other. by no ap- preciable quantity. The number of faces and the modes of formation of the erystals are also precisely the same. They are commonly obtained in the form of fiat tables. The primitive form is an oblique rhombic prism. M on M' = 118°.32’ M on P = 109 .48 As the crystals contain water from the mother liquor between these plates, it is not easy to determine with precision the amount of water in combi-: nation. I have determined it by finding the loss sustained on heating the salt below the melting point. By fusion, a portion is lost, as all the three combinations begin to volatilize at a red heat. The hydrous chloride consists of Chloride of sodium, 61.98 = 1 atom Water, 38.02 = 4 The hydrous bromide of Bromide of sodium, 73.6 = 1 atom Water, 26.37 = 4 atoms The hydrous iodide of Iodide of sodium, 79.77 = 1 atom Water, 20.23 —'4 atoms The hydrous common salt has been already described by Fuchs in his interesting paper on the solubility of common salt in water, but he was unable to determine all the angles—DMitscherlich, Poggend. An. der Phys. und Chim. xvii. 385. 5. Effects of heat upon copper ores.—In an able paper on the mixed ores of copper, lead, and iron, by Bredberg, a very striking fact is mentioned in regard to the effects of heat upon the sulphuret of copper which they con- tain. A mass of the ore apparently homogeneous, and containing through 358 Scientific Intelligence. its whole substance from four to five per cent. of copper by roasting, has its structure changed into a succession of layers. In one case cited there were two layers and a central ball. ‘The outer layer had an earthy frac- ture, and contained only three per cent. of copper. The second layer had the metallic lustre of copper pyrites, and contained twenty per cent. of copper—the internal ball, which contained fourteen per cent. com- bined with an excess of sulphur. Part of the iron was oxidized, but the proportions of the other constituents in the other parts of the mineral were unchanged. If the roasting be longer continued, a greater por- tion of the mass will be decomposed, but in the interior will be found a smaller bronze-coloured ‘ball, containing fifty-four per cent. of copper.— Kongl. Vetenskabs handling, 1828. ‘6. Preparation of Phosphorus. —Wohler recommends, as likely to give phosphorus at a very cheap rate, to distil by a strong heat ivory black with half its weight of fine sand and charcoal powder. A silicate of lime is formed, and the carbonic oxide and phosphorus come over.—Pog. An..de Phys. xvii. 178. 7. Hydriodic Ether.—Serullas gives the following improved process for preparing this substance. Into a tubulated retort are introduced 40 gram. iodine and 100 alcohol of 38° B. agitate and add 2.5 grains of phosphorus in small pieces. Distil nearly to dryness; add 25 or 30 grains alcohol, and distil again till nearly dry. Water throws down the ether from the solution. ‘After washing, it is to be distilled from chloride of calcium.— An. de Chim. xlii. p. 119. “8. Seleniuret of Palladium.—The seleniuret of lead of Tilkerode con- tains silver and native gold mechanically mixed in dendritic plates, and fine crystalline grains. Assessor Bennecke, the director of a work establish- ed on the spot for extracting the selenium and the precious metals from this ore, has obtained from his auriferous solution a considerable quantity of palladium. This has led Zincken * to examine the ore more attentive- ly, to find in what state this last metal occurs. The ore was boiled in nitric acid, which dissolved the seleniuret of lead, and separated many light silver white scales containing palladium. An examination of other specimens of the small scales and dendritic formations of native gold showed him many small scales having the form of six-sided tables, and re- _ sembling much the osmuriet of iridium, with here and there little groupes _ of crystal of a white colour like platina, and a perfectly meiallic lustre. Itis brittle, has a scaly shining fracture, and cleaves perpendicular to the axis ofa six-sided prism. By heat it swells and gives off a peculiar odour, like that emitted by seleniuret of mercury, and forms on the tube a red ring of selenium. By stronger heat a white vapour is given off, and the glass is corroded. With borax it gives‘a transparent glass, and melts into a brittle bead. This substance is a compound of the seleniuret of * Poggendorff, xvi. 495. OO _ Chemistry. 359 lead, silver, and palladium. A closer examination with a compound mi- croscope shows the scales of gold to be covered with minute white crystals of seleniuret of Palladium, invisible to the naked eye. The common sele- “niurets of silver and lead contain no trace of palladium... Zincken suggests, ‘that the native palladium of Sowerby may contain other ingredients ; but the experiments of Wollaston Srp 1a ai Ontety ie ‘it contains no selenium. 9. Huraulite and Hetepozite—Du Frenoy has analyzed these two minerals found formerly by Alluau in the Raeees: The Huraulite consists of Calculation. Oxygen. 8 Phosphoric acid, - ~° 38.00 36.52 Protoxide of iron, - 11.10 11.23 1 4 manganese, 32.85 34.95 3 Water, - - 18. . 17.26 99.95 99.96 The calculation is after the formula: 3 Mn’ P2 + Fs P2 + 30 ag This mineral is in minute crystals of the size of a pin head. The pri- mitive form is an oblique rhombic prism of 117°.30’, and 62° 30° ; but it occurs in the form of rhomboidal prisms, with or without the acute angles replaced. It shows no cleavages ; has a glassy fracture, and reddish-yel- low colour ; is transparent ; scratches calespar, but is scratched by steel. Its specific gravity = 2.27. It fuses with great difficulty before the blow- pipe, giving a black bead with metallic lustre. Ina tube it gives off water. It oceurs in the granite about Limoges. The only pieces yet found were picked up by Mons Alluau, near Strassenban. . The Hetraaiht is composed of Calculation. Oxygen. Phosphoric acid, 41.77 42.6 6 Protoxide of iron, 34.89 35.02 2 Protoxide of manganese, 17.57 18.10 I Water, - - 4.40 4.49 1 Silica, , en Wipe” 0.22 98.35 100.13 The calculation is according to the formula: S$ 2 F5 p + Mn? p2 + sa - 'This mineral is found only in scaly masses, cleaving, however, in three directions, giving ‘an oblique rhombic prism, having an angle of about 100° or 101°.- The-lustre is shining and ‘fatty, like that of the apatites. The colour greenish-gray or bluish. Weather-worn surfaces have a beau- tiful violet colour and a semi-metallic lustre. These weather-worn pieces . 360 Scientific Intelligence. cleave with greater ease, and ‘may be measured with the common gonio- meter. The undecomposed scratches glass with ease, but not quartz. In its de- composed state it is softer, and is scratched by steel. The specific gravity of the former is 3.524, of the latter 3.39. It dissolves in acid with a slight residue of silica. Before the blowpipe it melts into a dark-brown enamel. —Ann. de Chim. et de Phys. xli. p. 337. rade 10. Black Blende of Marmato.—An analysis of this mineral by Boussin- galt, shows it to be a compound of sulphuret of zine with i fs of iron, expressed by the formula . | S?+3ZnS? | Pog. Ann. der Phys. xv. 11. Sulphuret of Silictum.—Sefstrém has found that silica heated in his blast furnace in a charcoal crucible can be reduced by sulphuretted hydrogen to a sulphuret of silicium. It is easily volatilized, and in burning gives off the peculiar sublimate of silica, which has been repeatedly met with. This discovery will clear up many phenomena hitherto inexplicable. (Poggen. An, xvii. 379.) 12. New compound of Chlorine, Phosphorus, and Sulphur.—A new com- pound of these elements has been formed by Serullas. There are two chlo- rides of phosphorus, consisting of | Per-chloride. Proto-chloride. Phosphorus 1 atom. 1 atom. Chlorine 5 atoms. 3 atoms. When the per-chloride is introduced into an atmosphere of dry sulphu- retted hydrogen, it becomes heated, and changes in a short time into a colourless transparent liquid; while muriatic acid vapour takes the place of the sulphuretted hydrogen. When purified by distillation in a small retort, this compound has the appearance of the purest water- It is heavier than water; has a peculiar pungent aromatic smell, mixed with that of sul- phuretted hydrogen ; fumes slighty in the air, and boils at 125° centigrade, The odour of sulphuretted hydrogen is owing to the action of atmospheric moisture, for when decomposed by oxide of copper, it gives no trace of hy~ drogen gas. Its composition by the analysis of Serullas is 3 atoms chlorine. 1 atom phosphorus. 1 atom sulphur. 18. Atomic weight of Iodine and Bromine.—M. Berzelius has determin- ed that the atomic weight of iodine is 789.145, and the density of its va=— pour 8.7011. The atomic weight of bromine seems to be about 489.15, and the density of its vapour 5.3933.—Ann. de Chim, vol. xl. p. 430. . ‘ Fig rn} Natural History. 361 Ill. NATURAL HISTORY. ZOOLOGY. 14, Queries respecting the Natural History of the Salmon, Sea-trout, Bull-Trout, Herling, &c.—The value of the Salmon Fisheries in Great Bri- tain has decreased so much of late years, and particularly in the North of En- gland, and South of Scotland, that a remedy for it, independent of its interest as a difficult and unsolved question in Natural History, will become of no little importance to proprietors. The following queries are proposed, with the view and with the hope of gaining some information upon the natural history and economy of this valuable species. It is only by arriving at a cor- rect knowledge of its various habits, and those of the species allied to it, which frequent our rivers in almost equal numbers, that wecan hope to devise or accomplish any means of increasing the production, or of decreasing the certainly too extensive destruction of it in its different states. The queries relate only to its natural history, and answers are earnestly requested, stating facts relative to the opinions given, with the suggestion of additional queries, or any thing that will tend to illustrate the history of the species. Address the answers to Sir W. Jardine, Jardine-Hall, by Lockerbie, Dumfries-shire. Salmon. 1. At what age do salmon commence spawning? and how often is it supposed that they have migrated to and from the sea, previous to their first parting with the spawn ? 2. Do the males and females attain maturity at the same period or age? and do all of one age spawn nearly at the same season? 3. At what time do the young, or Fry, first leave the rivers ? 4. When do the young, or Fry, first return to the rivers ? 5. What is the size, weight, and appearance of the Fry, on their first return from the sea, and under what denomination do they then go? 6. Are they so far arrived at maturity as to spawn, and be productive on their first return from the sea, or previous to a second migration ? 7. Are any fish known to shed their spawn abortively, before they ar- rive at their full growth or maturity? or is the spawn observable in young fish, retained, until the parents attain the ordinary growth and size of the species when it is known to be productive ? Grilse. 8. Are Grilses immature Salmon, and if they are, what is their age? 9. What is the distinctive character between a large Grilse and a small Salmon ? 10. At what season do Grilses first appear in the rivers? What is their weight? and are they supposed to ne the he? of the same year, on their first return from the sea? 11. Have the Fry been marked, and afterwards taken as Grilses in the course of the same year, and have Grilses been marked, and afterwards taken as full grown Salmon? : 362 Scientific Intelligence. 12. Is it supposed that any sexual intercourse takes place between the Salmon and other species of the genus, thereby es a mongrel-or mixed breed of fish ? Whitling and Sea Trout. 13. Does the Whitling of the Tweed ever become a Salmon—if not, to what size and weight does it attain ? 14. Is the Whitling of the Tweed known by any other name in its various stages of growth ? Does it spawn, and at what season ? What are its migrations P 15. Is the Sea-Trout of some other rivers the same with the Whitling of the Tweed ? Is it found in all rivers containing Salmon ? Does it spawn e Is the young, or Fry known—and what are its migrations ? ’ Herling.* . 16. Is the Herling or Hirling of the Annan and Nith, and the Whiting of the Esk in Cumberland, the same with the Finnock of the west cpant of Scotland, and the Sewin of the Welsh rivers ? 17. Is the Herling found in the rivers on the eastern coast of ane or in any of the rivers in England or Ireland, and under what name or names is it there known? 18. Does the Herling spawn, and at what season? and is it known in any intermediate state between the Fry and Herling? Is the Fry anti and what are its migrations? f Bull Trout. 19. Is the Bull Trout of the Tweed the same with the Salmon Trout of the Tyne and Tees, &c.? and is it known by any other name during its growth from the Fry to maturity ? take 20. Is the Parr met with in all rivers containing Salmon? where and when does it spawn? Is it the same with the Brandling of the North of » England, and the Skirling of Wales? Is it supposed, to be a perfect: fish, or the Fry of some species of Salmon ? 21. What is the Grey (Salmo Erioxr) of Dr Fleming? What are its states from the young to the adult ? What are its migrations? : 22, Are there any species of migratory Salmon, distinct from those above mentioned, known in the rivers of your neighbourhead ? 15. The Capercailzie—The Capercailzie, or cock of the woods, existed for- merly both in Ireland and Scotland ; and, according to Shaw, one was killedjin the latter country, about fifty years ago, at Lochlomond. It is much to be re- gretted that so magnificent a bird should have been lost ; and it would be well worth any attempt to recover the breed. In Scotland there would be little doubt of its succeeding, if it could but be procured in sufficient numbers to make the attempt. The cock of the woods is by no means a difficult bird to rear, even in a state.of captivity. There are several in- stances of its being kept alive in Sweden; and but very recently Captain * The Herling seems to be the Salmo Albus of Dr Fleming’s “ British Ani- mals,” and most ichthyologists—the species has not been thoroughly investigated. ” 3 : -General Science. 363 Brooke was informed of two, where the female was sitting on several eggs, the result of which he was not acquainted with. All that it requires in its natural state is a considerable tract of wild country, well wooded with the fir, which may be considered necessary to the bird, as on its shoots it princi- pally subsists during winter. If there be also a wide extent of mountains and high lands, it will be more favourable; and should the cranberry, the whortle or blackberry, and the other wild fruits which these situations pro- duce, be found in abundance, the trial would, in all probability, be attend- ed with success. In every part of Sweden they are found in abundance, as also in the southern parts of Norway. The soil, generally speaking, in both countries, is of a light and sandy nature ; the forests almost wholly composed of fir, generally with little underwood ; and the earth covered with the different kind of berries just noticed. -What brushwood there is, is frequently the juniper and low birch, the berries of the former being also a favourite food of this bird. No attempt, Captain Bruoke thinks, would ever succeed to rear them in this country by bringing their eggs over. Without speaking of other objections and impediments, the difficulty of meeting with the eggs would be sufficient. The peasants even seem to consider this as in a manner proverbial ; and Captain Brooke never met with any one of them who had either seen the eggs or discovered a nest- The way in which they take the birds is principally by means of the gun, though sometimes snares are used. The offer of a good price is all that would be necessary ; and with this temptation, there would be little fear of any insu- perable difficulty. The old ones alone should be brought over, or birds of sufficient age to cause no apprehension in this respect. All the attempts that have been made by transporting young birds have uniformly failed from their dying shortly afterwards, whereas the old ones have lived. The female bird, during the period of incubation, is extremely shy, readily for- saking her nest when disturbed. In general, she lays as many as ten and twelve eggs, which are nearly equal in size to those of ahen. The ground of them is tawny white, but thickly covered with small blotches of a red- dish brown, a few specks being some shades deeper, and approaching to black.—When the young birds are hatched they resemble the mother, and remain so till autumn, when the black plumage of the male begins to ap- -pear.—Vide Captain Brooke's Travels in Lapland. 16. The Portuguese Man of War.—aA recently published _ number of the North American Review contains a description of a natural object but little known to common readers, though said to be fa- miliar to those who navigate between the tropics, the beautiful and enigmatical insect commonly called the Portuguese Man of War. It is from a Memoir to Dr Tilesius, who accompanied Mr de Krusenstern _ in his voyage round the world. “‘ This singular animal had several times been delineated, described, and endowed with names ; yet not only its de- nominations were various, but also the nature and shivnatesiahal ascribed toit. According to some it was a polypus, according to others a zoophyte, and others ranged it among the Mollusca. Naturalists who followed in the steps of Linneus have called it the Physalis. Wonderful as are all 364 Scientific Intelligence. the works of Providence, admirably fitted as are the several parts of each ereated being for their several functions, complex in their composition as they sometimes at first seem, while yet they are always found to be really so simple and suitable in their action on a nearer investigation, we may nevertheless venture to rank this little animated creature among the most curious phenomena. A worm between six and eight inches in length, which is found but in certain latitudes, has seemingly the skill and know- ledge of an experienced navigator, and is in itself a little ship. Its evolu- tions are according to the winds; it raises and lowers its sail, which is a membrane provided with elevating and depressing organs. When filled with air, it is so light, that it swims on the surface of alcohol, and is at the same time provided with a structure, which furnishes it with the necessary bal- last. When high winds would endanger its existence, it descends into the deep, and is never seen on the surface of the water. From the under side of the body proceed tubes, which extend twenty feet in length, and are so elastic and delicate, that they wind in a spiral form like a screw, serving at once as anchors, defensive and offensive weapons, pneumatic tubes and feelers. ‘The insect has the colours of the rainbow ; its crest, which per- forms the office of a sail, is intersected with pink and blue veins, trimmed with a rosy border, and swells with the winds, or at the animal's pleasure. The fibres contain a viscous matter, which has the property of stinging like nettles and produces pustules. It acts so strongly that vessels in which they have been kept for a time, must be repeatedly washed before they . can be used. These fibres may be cut off without depriving them or the rest of the insect of the principle of life; and the separation takes place spontaneously, whenever the glutinous matter comes in contact with a hard surface like the sides of a glass globe. The insect has, however, dangerous enemies in small dolphins, and meduse, against which neither its nautical skill nor its poison can defend it.” IV. GENERAL SCIENCE. 17. Burning Coal Mine at New Sauchie—It is now more than two years since the snow lying on a field on the farm of Shaw Park, belonging to the Earl of Mansfield, was observed to melt almost as soon as it fell, and then rise in a state of vapour. The phenomenon attracted the attention of the managers of the Alloa and Devon collieries, and was found to be the effect of the heat produced by a stratum of coal in a state of ignition, techni- cally known by the name of the nine. feet seam, from which the Devon iron works are supplied with a large proportion of their fuel. Various plans were at the same time suggested to extinguish the flames, and after several failures, it was determined to cut a mine round the seam to prevent their extension. Workmen were set to excavate this mine, which was opened at both sides of the seam, to build a wall as they. proceeded, on the sides of the two tunnels next the fire. In this way it was intended to pro- ceed, till the tunnels penetrated beyond the fire, when they were to be joined in the form of a horse shoe, and thus cut off, by means of a strong wall, all connection between the ignited part of the seam and the remain - der of it. This plan has been pit iii in for a year and a half, but has General Science. 365 never been completed. The workmen have often brought the two walls within a few fathoms of meeting, but owing to the fire bursting in upon them, they have been hitherto obliged to fall back again and take a wider circle. Six or seven shafts. have been sunk to ventilate the tunnels, in which the heat is frequently so great as to raise the thermometer from 212 to 230 degrees of Fahrenheit ;—it sometimes rises even higher. The lamps of the miners which are hung upon the walls, have more than once fallen to pieces from extreme heat.—Stirling Journal. 18. Hay converted into a Siliceous Glass hy Lightning.—In the summer of 1827, a rick of hay in the parish of Dun, near Montrose, was set on fire by lightning, and partly consumed. When the fire was extinguished by the exertions of the farm-servants who were on the spot, there was ob- served in the middle of the stack a cylindrical passage, as if cut out by a sharp instrument. This passage extended down the middle of the stack to the ground, and at the bottom of it there was found « quantity of vitri- fied matter, which there is every reason to think is the product of the silex contained in the hay which filled up the cylindrical passage. The existence of silex in the common grasses is well known, and the colour of the porous and vesicular mass is very like that which is obtained from the combus- tion of siliceous plants. We have been indebted for a specimen of the sub- stance to Captain Thomson of Montrose, wlio examined the spot almost im- mediately after the accident had taken place. 19. Application of Zinc to Roofing of Houses.—It is perhaps not gene- rally known that this metal rolled into large plates has been for some years adopted on the Continent as a substitute for lead and slates in the roofing of houses, and is now applied in this country to the same purpose in cover- ing of public and private buildings. Roofs made of those plates are so light, that the timber requires not to be above half so. strong as for lead or slates, there being only about one-sixth part of the pressure. Very hand- some water cisterns and rain water pipes, &c. are also made out of zine, specimens of which, we understand, may be seen at Mr Joun Crarx’s zine warehouse, No. 38, George’s Street. As an important saving is said to be obtained from the use of this metal, it appears particularly deserving of at- tention. by those who are engaged in architectural improvements ; and,. as the ore exists in great abundance in this island, were it extensively used - for the above purposes, a considerable consumption of one of the natural products of the country would be the consequence.. + . 20. M. Utenhove on Spherical and Parabolical Specula for Teleseopes.— In the new Memoirs of the first class of the Royal Institute of the Nether- lands, vol. ii. part ii. lately published, there is an Optical memoir by M. Von Uterhove, in which he treats of the difference between spherical and parabolical specula employed for telescopes. His principal object is to de- termine what is the greatest error which is committed by substituting one of these conic sections for the other, and he has considered the question in a geometrical aspect. He afterwards applies his formula to the principal known telescopes, and he finds, that in the great telescope of Herschel, for 366 _ Scientific uhieMgence example, the grbshens errot, in substituting a spherical fora penstoalians mirror, amounts to iazgth of a line. 21. Iron Trade of Great Britain —The whole i iron made in Great Bri: tain has been as follows :— Tons. t 1740, 17,000 from 59 furnaces. , 1788, 68,000 121 furnaces. 1796, 125,000 1806, 250,000 ae 1820, 400,000 1H 1827, 690,000 284 furnaces. The iron produced in 1827 was made as follows : Tons. South Wales, 272,000 90 furnaces. Staffordshire, 216,000 95 Shropshire, 78,000 31 Yorkshire, 43,000 24 Scotland, 36,500 18 North Wales, - 24,000 12 Derbyshire, 20,500 14 690, 000 284 About 3-10ths of this is used for home consumption, and the other 7-10ths exported.—Repertory of Arts, October 1828. 22. Explosion at the bottom of a Well at Bologna. The well where this explosion took place is in the house of M. Berni Degli Curteni. As nothing’ preceded the explosion, the inhabitants of the house were greatly alarmed. The water of the well was analysed by Professor Sgarzi, who discovered — in it only a little carbonic acid and salts, with a caleareous basis. M. Criole ascribes the explosion to the vapours of the water, and to the gas arising from the sulphuret of iron, with which the water has come in contact by infiltration, and to a winter excessively wet. The Fumaroli of Naples and the Grotto del Cane are analogous phenomena, and the Professor might’ have added also the slight commotions which the ground frequently expe- riences in the neighbourhood of the thermal springs of the Pyrenees, the heat of which is kept up, as is well known, by the constant er oe ‘ of the sulphurets of iron.— Rev. Encyclopédique. | 23. Destruction of Live Stock hy Wolves in Russia.—In the government of Livonia alone, the following animals were destroyed by wolves in 1823. The account is an official one. Horses, - - 1,841 Goats, - - 2,545 Fowls, - - 1,243. - Kids, = - 183 Horned Cattle, - 1,807 Swine, = - ‘4,190 Calves, ~ = 733 Sucking pigs, ‘. 312 Sheep, a ~ 15,182 Dogs, « = 708 Lambs, + - 726 Geese} - - 673 General Science. 367 24. Supposed Series of Sub-marine Banks from Newfoundland to the En- glish Channel—From the Great Bank of Newfoundland to the English channel, it was found that whenever we approached towards the Vigias, or dangers laid down in the charts, the water changed from the deep blue of the ocean to green ; in some instances to alight pea green; and this co- lour was not the effect of any change in the state of the atmosphere, but remained the same under the dfferent alterations of sunshine, cloudy wea- ther, and haze. These changes were so remarkable, that they became the subject of conversation on board, and occupied my attention particularly. On an inspection of the chart, I came to the conclusion that, as this part of the north Atlantic, lying between Newfoundland and the English channel, crosses the meridian of the volcanicislands of Iceland and the Azores, there are connecting ramifications between the subterranean fires of Iceland and those of St Michael of the Azores, and that the spaces of green water" over which we sailed in this route, were indications of the superior elevation of the bottom of the ocean in the lines of communication between the two volcanic lands above-named ; and the coincidence of the water changing colour as we approached the different rocks, shoals and islets, placed in the chart in this part of the Atlantic, (some of which have been verified) sup- ported the probability of the conclusion I had drawn. Assuming, there- fore, that these banks, (which I conceive to be detached, that is to say, having deep water between them from N. to S.) exist, and are the lines or conductors of volcanic matter from Ireland to the Azores ; we may readily account for the appearance and disappearance of such islands, rocks, &c. as Buss Island, the rocks seen by. Sir Charles Knowles, those looked for by Admiral Rodney, westward of Ireland, Jaquett Island, the Devil’s Rock, and the Eight Stones north of the Madeiras, &c. &c. because we have un- doubted proofs that sub-marine volcanoes throw up islands and rocks from a very great depth, asin the instance of Sabrina island off St Michael’s ; and that islands disappear from the same cause, as instanced in the sub- mersion of Gouberman’s islands on the coast of Iceland, and Rober’s isle at the Cape of Good Hope. I consider, therefore, that from the longi-. tude of 10° W. to the Banks of Newfoundland, and from the Madeiras to Iceland, that is from 32° N. to 65° N. the ocean comprised within that area, is the seat of the different branches of sub-marine volcanic matter in the north; and this may account for the frequent shocks of earthquakes felt in Great Britain and Portugal. As far as my own ideas go concerning volcanoes, I am willing to believe, that throughout the whole earth they are connected by subterranean and sub-marine tubes or channels, and this hypothesis is borne out by facts so plain, as to be almost demonstrative with regard to earthquakes, which philosophers consider as * Jt may be worthy of notice, as a circumstance strengthening my opinion, that the Medusz, Polypi, &c. were infinitely more abundant in these spaces of green water, than in those of a blue colour ; indeed, very few of the larger species of these animals were seen in the latter, they were generally of the small orbicular kind ; whereas in the green water they were frequently from three to five feet diameter, of an infinite variety of shapes and of the most brilliant colours, 368 Scientific Intelligence. occasioned by subterranean fire and water creating an exploding gaseous ftuid. Upon this view of the subject, we might carry our line from the Madeiras to the Canaries, proceeding on to the Cape Verds, St Helena,* &c. &c. and it has often struck me, with respect to the Atlantide Island of the Ancients, if such éyer existed, that it occupied that space of the ocean lying between Porto Santo and the Azores, and that these islands formed the extremes, the centre part having sunk into the bosom of the deep by the agency of volcanic fire. I may close these remarks by observing, that the captain (an officer of the navy, possessing experience and scientific knowledge) of the vessel in which I was, appeared at first sceptical with respect to my hypothesis, but at last, from his own attentive observations, became fully convinced of its pro- bability.—United Service Jourual, No. 14, 1830. . 25. New Islands on the Coast of Japan.—Captain Coffin of the Nantuc- ket has. discovered six new islands situated near the coast of Japan, from which they are distant only four days sailing. They form a group situated to the south of Sandown Point. The Bay in which Captain Cof- fin cast anchor is.in 26° 30’ of north latitude, and 141° of east longitude from Greenwich.— Communication from Mr Warden to the MRT of crit January 1828. 26. Agitation of the Sea in the Channel, and ‘Earthquakes in Italy.—Dur- ing the eight or ten days which preceded the 17th of April 1828, an ex- traordinary motion of the sea had been felt in the channel, insomuch, that several outward bound vessels could not proceed to the westward of the Lizard ; and the rise of the tide had been great for several days, viz.—nine- teen feet, which produced a grand and terrific burst upon the Breakwater, many feet above the crane-head. We then were of opinion, that the ex- traordinary circumstance alluded to was caused by some convulsion of nature in some other quarter, and the information recently received proves that our opinion was correct. It appears that on the 10th of April, and subsequent days, shocks of earthquake were felt at Rome, Florence, and other parts of Italy. Now, as the extraordinary motion in the channel, and the shocks in Italy were felt at the same time, is it not fair to pre- sume that the one was caused by or hal connection with the other ?— Plymouth Journal. we 27. Great Rain in Perth on the 3d August 1829.—In a shower which seems to have been confined to the immediate vicinity of Perth, no less than four-fifths of an inch of rain fell in the course of half an hour. On the Oroonoko Humboldt observed 14 inch of rain fell in three hours.— Perth Courier, 7th AUgH Es 28. Earthquake a Bogota on the 17th June.—We are in a state of great excitement, and anxiety. Last night was the most awful one I ever passed. * All those islands are of volcanic origin. General Science. 369 We were sitting at whist as the clocks chimed a quarter to eleven ; at that moment we were all sensible of the shock of an earthquake, and we pur- sued our game. About two minutes elapsed, when we experienced a most awful repetition. The walls of the house were dreadfully agitated, our candles were overturned, chairs and tables thrown from one side of the room to the other—we could ourselves scarcely maintain our erect po- sitions; and were so perfectly paralyzed, that we never thought of getting ‘ out of the house ; indeed, my own belief was, that the house must full be- fore we could possibly escape. The ceiling was coming down upon us in large flakes, and the fall of a large mirror at the moment, which we took to be part of the house, added to the alarm. It lasted forty seconds. We then went into the street, where crowds were on their knees praying most fervently. A general rush was made for the square in which the palace is. There we found thousands collecting and collected ; women and men just as they had jumped out of bed, with the addition of a blanket thrown around them—mothers in the agony of grief and apprehension, clasping their children to their bosoms—fathers and brothers endeavouring to provide them with covering—groups of females in every direction calling each other’s names to be assured that all was safe. Dismay and despair were general. No one would return home, and thousands passed the whole night in the square. Three o'clock, rp. m.—TI have just returned from making a round of the town, to observe the extent of damage. Several houses are thrown en- tirely down ; many are rent asunder from top to bottom. The cathedral, a splendid edifice, has one of its wings rent from the base to the tower. Scarcely a house in the city is without injury—mine has every one of its principal walls split in several places ; the dining-room is in ruins ; the par- tition of my bed-room has fallen in: and had I been in bed I should have been at least severely bruised. A severe shock has not been felt here un- til now, since the year 1805., About six years ago, it is said, there was a slight one, but no injury was done. It appears miraculous that only three lives have been lost.. Many who are here, and were at Caraccas, during the great earthquake there, say, that this shock was much more severe ; but the houses being better built here, the injury has been less. Half-past five o’clock.—I have been taking another survey, and was surprised to find that hundreds of families are sending beds and bedding into the plain, and erecting booths there for the night.—All fear another shock. 19th, Twelve o'clock, noon.—This night has passed quietly, and the alarm is subsiding.— Letter from Bogota. 29. Earthquake in the Netherlands, 23d February 1828.—The number of earthquakes which are on record as having been experienced in the Netherlands for many centuries past, does not exceed six or eight ; and none of them have been productive of disastrous effects. Within a space of ten years, during the last century, three only took place, one of which happened in 1755, immediately after the great earthquake at Lisbon ; and the last was in 1760. The one which has lately occurred was particularly NEW SERIES, VOL. III. NO. II. OCTOBER 1830. Aa 370 List of Scottish Patents. felt along the banks of the Meuse ; and its greatest violence was felt in thé towns of Liége, Tongres, Tirelemont, and Huy: many of the walls and buildings of which suffered considerable injury ; but happily no lives were lost. In the adjacent towns of Maestricht, Namur, Louvain, and Brussels, strong shocks were also experienced ; but their violence diminished in pro- portion to the distance from the former or principal seat of concussion. They appear also to have been sensibly felt at Bonn, Dusseldorf, and Dor- drecht, on one side, and at Flushing, Middleburg, and Dunkirk, on the other; although they were not perceptible at many of the intermediate towns. Slight shocks were also experienced at several of the frontier towns of France, as Avesnes, Commercy, and Longuyon ; as also at the coal-mines near Liége, atthe depth of from fifty to, sixty toises; in which latter. case they were accompanied by a hollow sound, resembling that of a heavy laden waggon. The direction in which the shocks were propagated appears to have been from east to west. For some time before the earthquake the weather had been fine ;- butt became cloudy on the evening which preceded it, and continued so for ser yeral subsequent days.. At Brussels the barometer had fallen during the three preceding days from 29.421 inches to 29.044; on the night. before the earthquake it had risen to 29.126 ; and a few moments after the event, it stood at 29.233. It continued afterwards to rise ; and on the 27th it had reached 30.166. At Liége, however, the barometer repained, very low after the earthquake. The shocks lasted about eight or ten seconds, There have been experienced, since the 23d of February, slighter ea these also were preceded by a great depression of the Deen Sot Mag. July 1828. — ‘ Or. Wii iG me id 30. Prizes.—The President and Council of the Royal Society of London have adjudged the first royal medal to Charles Bell, Esq. for his, re- searches relating to the nervous system, and the second, to M. Mitscherlich for his discoveries relating to the laws of is baairaeod and the pene ties of crystals. ; 4 -e Saat eM , Art. XXIV.—LIST OF PATENTS, GRANTED IN SCOPEAND SINCE SEPTEMBER 23, 1829. 4 - 26. September 23. For certain Improvements on ‘or. additions to. Fire Places. To JosepH ANGE Fonzi, Esq. county « of Middlesex. _ rap Cannon. To ‘Sure Tucker, county of Middlesex, 28. September 23. For certain Improvements in ‘Lee 4 be Ap- plied to Fowling Pieces and other Fire Arms in place of Locks. To Davip Laurence and Jonn CrunpweELt, county of Kent. 29. September 25. Fora New Process or Method of Whitening Sugars. To Josnua Bares, city of London. 30. September 25. For an Improved Method of Gaertings Steam- List of Scottish Patents. ‘S71 Boilers or Generators, whereby the bulk of the boiler or generatér and the consumption of fuel are considerably reduced. ‘To Josnua Bates, -eity of London. _ 31. October 28. For certain Improvements in Dimistiing’2 Friction in Wheeled Carriages to be used on Rail-Roads, and which Improvements are Applicable to other Purposes. To Ross Winaws, county of Sussex. 32. October 28. For a certain Improvement or Improvements in Distilla- tion. To Wiitiam Suanp, Esq. county of Kincardine. 33. November 3. For certain Improvements in the Construction of Anchors. To WitLt1am Roneer, county of Middlesex. » 84. November 6. For certain Improvements in the Process of Manu- facturing Soap. To Cuartes TuRNER STURTEVANT, county of Middle- sex. 35. December 17. For certain Improvements in Machinery for Spinning Cotton and other fibrous substances. To CuHartes Broo, county of York: 36. December 17. For a New Preparation or Mamufacture’ of a certain material produced from a vegetable substance, and the application thereof to the purposes of affording light, and for other uses. To James SOAMES Junior, county of Middlesex. . 1, January 25, 1830. For an Exploding Shot or Projectile. To Joun Tucker, county of Middlesex. . 2. February 2. For a New Alloy or Compound Metal applicable to the Sheathing of Ships and various other useful purposes: To Joun Revere, New York. 3. February 2. For a Machine or Hydraulic Engine for applying the power or pressure of Water, Steam, or other elastic fluids to the purpose of working Machinery and other uses requiring power, and applicable to that of raising or forcing fluids. To Epwarp Daxeyne and JAmEs DakeEyNe, county of Derby. . 4. February 8. For an Improvement in Ships’ Windlasses. To Groree STraAKER, county of Durham. ° _ §. February 9. For an Improvement in the Manufacture of Canvas and Sail-Cloth for the Making of Sails. To James Ramsay and ANDREW Ramsay, Greenock. 6. February 13. For an Improved Mechanical Power Applicable to Machinery of different descriptions. To THomas Joun Futter, county of Middlesex. 7. February 16. For certain Improvements on, or additions to, Wheels or Apparatus for Propelling Vessels and other purposes. To AuTon Bran- HARD, county of Middlesex. 8. February 19. For an Improved Method of Manufacturing Salt. To Joun BraitawatTeE and Joun Ericsson, London. 9. February 26. For an Improvement in the Apparatus used for Dis- tilling. To Parzicx Dawson, Lillyburne. 10. February 26. For certain Improvements in Apparatus aied for Dis- tilling and Rectifying. To Rozert Busx, county of York. 11. March 3. For the manufacture or preparation of certain substances ' * 372 List of Scottish Patents. which he denominates the British Tapioca, and the Cakes and the Flour to be made from the same. To Jonn M‘Innzs, Esq. of Stirling. | 12. March 16, For certain Improvements in the Construction of Win- dow-Frames, Sashes, or Casements, Sun-blinds, Shutters, and Doors, de- signed to afford security against Burglars, as well as to exclude the weather. To ANDRew SmitTH, county of Middlesex. 13, March 16. For certain Improvements in Apparatus.and Machinery for Cleansing and Deepening Rivers, and in the method of applying the same. To Tuomas Arrieck, Dumfries. 14. April 13. For certain Improvements in Machinery for Spinning Cotton, Silk, Linen, and other Fibrous Substances. To JAMES merc: Esq. county of Lancaster. 15. April 29. For certain Improvements in Making or Manufacturing Bolts or Chains. ‘To Samuret Brown, Esq. London." 16. April 29. For certain Improvements in the Means of Keeping or Preserving Beer, Ale, and other Fermenting Liquors. To WuLt1am AITKEN, Esq. Scotland. 17. May 3. For certain Improvements in Apparatus for Making anil Supplying Coal Gas for useful purposes. To Ricuarp Wirry, one of Stafford. 18. May 12. For certain Improvements on Steam Boilers and in Car- riages or Apparatus connected therewith. To James Viney, Piccadilly. 19, June 14. For a New Method of Purifying and Whitening Sugar or other Saccharine Matter. To Epwarp Turner, county of Middlesex. 20. July 21. For an Improved Engine for Communicating Power for Mechanical Purposes. To Joun Ericsson, London. 21. July 29. For certain Improvements in Preparing or Finishing Piece Goods made from Wool, Silk, or other fibrous substances. To JoHNn Freperick Smits, Esq. county of Derby. 22. July 29. For certain Improvements on Steam Carriages and in Boilers, and a Method of producing increased Draft. To Joun Rawz Junior, county of Middlesex. 23. August 3.. For an Improvement or Improvements in the Method or Apparatus for Separating the Knots from Paper, Stuff, or Pulp, used in the Manufacture of Paper. To Ricuarp Inotson, county of Middlesex. _ 24, August 19. For certain Improvements on, and Additions to, Machines or Machinery to be used and applied for conducting to and winding upon Spools, Bobbins, or Barrels, Rovings of Cotton, Flax, Wool, or other fi- brous substances of the like nature. ‘To Josrru CurssrBonovuen, county of Lancaster. 25. August 19. Fora Method or Process of giving a Metallic surface to Cotton, Silk, Linen, and other fabrics. To Joun Yates, county of Chester. 26. August 19. For a New Method of making Iron Wheel Barrows of wrought Iron, with a wrought Iron Wheel, by which New Method, said Iron Wheel Barrows can be made lighter, stronger, more durable, and cheaper than any iron wheel barrows which have been heretofore in use: To Witt1am Matter, Dublin. Celestial Phenomena, October—December 1830. 373 27. September 6. For an Improved Machinery for the Navigation of Vessels and Propelling of Carriages. .To Joun Rutuven, Edinburgh. Art. XXV.—CELESTIAL PHENOMENA, From October 1st to December 31st, 1830. Adapted to the Meridian of Greenwich, Apparent Time, excepting the Eclipses of Jupiter's Satellites, which are given in Mean Time. N. B.—The day begins at noon, and the conjunctions of the Moon and Stars are given in Right Ascension. OCTOBER, m OH. Wel & H. M.S 15 6 8 14 Im. IV. Sat. 7/ 19 57 9 Full Moon. 1 7 2a ll 15 © 18 5 40 3 Em. I. Sat. 2/ 11 41 31) ¢7 8 ) 35’ N. | 21 om 18 53) da & NIN. | 22 6 37 +) enters 8 4 4 iy 22 23 44 ) First Quarter. 10 32 Last Quarter. 23 & 19 7 Em. HI. Sat. 2/ 1 ds Ty 23 21 oe 7 6 3Em. 1. Sat. 2/ 24 5 40 45 Im. IIL. Sat. 27/ 12 45 9 Inf. d © 28. 10 d land 2 6 ny 19 Pm. 29 9 3 9)dy 8) AN. Stationary. 29 15 13 51) da B ) 29'N. 7 3i New Moon. 29 15 8 Full Moon. Stationary. 29 16 dv Ty . Stationary. 10 enters NY DECEMBER. 10° 20 First Quarter. 5 26 53) d2 dia Ss. Greatest Elong. 3 16 Sup. 4 d 6 15 16 Last Quarter. Wwe oe 3 7 10 2 18) 6AM) 6N. 7 1 5) dH p72 vn. 12 Stationa’ 8 39 2)SuCeti) 7’ N.| 12 7 59 2) dy) 3IN. 5 18 Full Moon. 14 20 19 New Moon. 20 16 Sup. 6 © NOVEMBER. 21 19 8 (*) enters 3 59 13) dah jp 20’N. | 22 10 42 First Quarter. 22 53 ( Last Quarter. 25 4 49 39) dw Ceti ) 57’ N 10 Pda ll 27 1 36°35) 628 )74s. 4 d a TY | Sat Sie Full Moon. 1 55 Fa New Moon. 29, 2 ger Times of the Planets passing the Meridian. OCTOBER. Mercury. Venus. Mars. Jupiter. Saturn. Georgian. RES | RN ion Be ne bis 4 Ia i % hy its Bont . kO 22 49 ll il 6 AG... Ol ao 8 7 13° 23 47 23 «=O 10 19 5 32 20 50 7 23 25 22 55 23 10 9 33 4 53 20 9 6 38 NOVEMBER. 1 22 56 23 (16 9 8 4 31 19 43 6 ll 13 23 17 23 «25 8 29 3 52 18 58 5 24 25 23 42 23 «36 7 53 3 12 18 10 4 36 7 ; 374 |. Mr Marshall’s Meteorological Observations © DECEMBER. ey eee ee Ve note Arg 9: Cee i 1.23 566 2341: 9°36 2 5147 450 4 13° 0 22 23 53 Vice 2 10 16 53 3 21 25 0 53 0 5 6 31 1. 28 16 59 2 30 Declination of the Planets OCTOBER. Mercury. Venus. Mars. Jupiter. Saturn. Georgian. D. o 674 ° , ° ‘ ° 4 ° ¢ ° : ; I 14108. 6 8N. 6518. 23 25S. 13 29N. 19 J6S. 13. 8 38 020N. 6 48 23 21 13 6 19 17 25 3.44 5 35S. 6 52 23 14 12 46 19: 17." NOVEMBER. 1 6 6S. 8568S 5 5S 2385 12 33N. 19 15S. 13 13 12 14 17 3 20 2256 3=12 22 19 IL 25 19 45 18 45 110 22 40 12 13 19 7 DECEMBER. 1 2214S 2033S. 0 IN. 2231S. 12 11IN. 19 88S. 2 9 234 2 33 2210 +12 11 18 56 25 2445 2354 5 14 2144 1217 18 46 a — i Art. XXVI.—Summary of Meteorological Observations made at Kendal in June, July, and August 1830. By Mr Samuvet Marsnatt. Com- municated by the Author. State of the Barometer, Thermometer, &c. in Kendal for June 1830. Barometer. : Inches. Maximum on the 9th, - eC ‘J 30.06 — Minimum on the 4th, 2 . 3 @, ‘29:34 Mean height, : ‘ : ‘ - 29.65 Thermometer. 4 _ Maximum.on the 27th; » ‘ eri t 65.5° - Minimum on the 5th, é é > 39° Mean height, 2 : ME Aah -52.20° Quantity of rain; 5.289 inches. Number of rainy days, 21. Prevalent winds, north and west. This has been a very rainy and unsettled month, and but little progress made in the hay harvest in consequence. The showers have been seldom heavy, but of long continuance, and they have been mostly of a drizzling kind. The weather has been generally cold for the season, as the mean indicates, and far from genial. The barometer has been mostly about a mean height. The winds from the north have been much more Lita than is common in this month.; inade at Kendal in June, July, and August 1 830. 375 3 July. Barometer. Inches. Maximum on the 28th, - : - 30,23 Minimum on the 9th, - , ; 29,15 Mean height, - - - . 29,74 © Thermometer. Maximum on the 31st, - 4 a ~ gle: Minimum on the 11th, - - - 42° Mean height, - - - - 58.59° ©. : Quantity of rain, 4.961 sein Number of rainy days, 19. Prevalent wind, west. Till the 26th, there were but seven days on which a greater or less quantity.of rain had not fallen. The last week in the month was very seasonable, and for a few days the weather was hot. On the 30th we had | a tremendous storm of thunder and lightning, which extended to several counties round this, and in most places was very severe: though this town appears to have been near the centre of its extent, The wind was in the west 14, and in the S. W. 11 days in this month. August. Barometer. Inches. Maximum on the 19th, “ eels 30.05 Minimum on the 28th, - oer : 29.08 Mean height, . > : - . 29.66 i Thermometer. Maximum on the 15th, © - ‘ * 63.5° Minimum on the 18th, - | 39 Mean height, = > ei - . , 54.64° Quantity of rain, 4.218 inches. Number of rainydays, 19. Prevalent wind, west. Though we have had no great weight of rain during this month, yet the prevalence of showers has been so great, that we have seldom had an interval of more than a day at a time of fine weather. Though the even- ings have begun to feel sufficiently chill to remind us of the approach of - Autumn, yet the temperature through the days has been remarkably uni- form, the highest that the thermometer hag reached being 634, and the lowest 56°, in the day time ; and during the nights, the variation has been between 56° and 39°: of course we have had no frost in this part of the valley, though in the high land in the neighbourhood there has been a: hoar frost occasionally. The total amount of rain for the year is 33.203 inches,—a much smaller quantity than might have been expected from the number of rainy days, for in the last five months, out of the 153 days in that period, there have been 94 on which rain has fallen. 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