ferent times, even from the same kind of oil, owing to variations of temperature, and other circumstances. Essentially, the gases derived from oil and coal are composed of the same ingredients, though in different proportions, viz. simple hydrogen, light carbureted hydrogen, and carbonic oxide gases, with the addition of variable proportions of an elastic fluid, which agrees with olefiant gas in being condensible by chlorine, but combines more oxygen, gives more carbonic acid by combustion, and has a higher specific gravity than olefiant gas, or even than common atmospheric air. Whether this ingredient be strictly a gas, permanent at all temperatures, or a mixture of olefiant gas with some new gas, constituted of hydrogen and charcoal, in different proportions from what are found in the known compounds of those elements, or merely the vapour of a volatile oil, the author leaves to be determined by a future course of experiments, The only paper of any interest read to the Society in the course of March, was one by the President, Sir H. Davy, on the Papyri of Herculaneum. In this paper Sir H. gives an account, 1. Of his first experiments, performed in England in 1818, upon several fragments of papyri, which induced him to hope that chemistry might afford some assistance towards unrolling these interesting relics. 2. Of the state of the MSS. found at Herculaneum. 3. Of the chemical processes employed on the MSS. in the Museum at Naples, and of the reasons which ultimately compelled him to abandon the attempt; together with some general observations on the MSS. of the ancients. The papyri in question appear to consist of leaves reduced to the state of cinder, cemented by a matter soluble in certain liquids, but especially in muriatic and nitric ether. Now, as chlorine, while it has a strong attraction for hydrogen, exerts no ac- has been adopted for unrolling the volumes of carbonized papyrus, and it is entirely mechanical. It is the invention of Piaggi, a native of the Roman States, and consists in applying a thin animal membrane, (gold-beaters' skin), by a solution of glue, to the back of the MS., and carefully elevating the layers when the glue is dry. Alcohol and ether were found useful auxiliaries in this delicate operation, and great advantage was also derived from throw ing heated air upon the surface of the leaves, precaution being taken that the temperature should not be too rapidly raised. The different MSS., however, required very different treat ment. During the two months Sir H. Davy was employed in these experiments at Naples, he succeeded, with the assistance of the persons attached to the Museum, in partially unrolling about 23 MSS., from which fragments of writing were obtained, and in examining about 120 others, which gave no hopes of success. "And I should gladly have gone on with the undertaking," he adds, "from the mere prospect of a possibility of discover ing some better results, had not the labour, in itself difficult and unpleasant, been made more so by the conduct of the persons at the head of this department in the Museum. At first every disposition was shewn to promote my researches; for the papyri remaining unrolled were considered by them as incapable of affording any thing legible by the former methods, or, to use their own words, disperati; and the efficacy and use of the new processes were fully allowed by the Svolgatori, or unrollers of the Museum; and I was for some time permitted to choose and operate upon the specimens at my own pleasure. When, however, the Rev. Peter Elmsley, whose zeal for the promotion of ancient literature brought him to Naples, for the purpose of assisting in the under taking, began to examine the frag ments unrolled, a jealousy, with regard to his assistance was immediately manifested, and obstacles, which the kind interference of Sir William A'Court was not always capable of removing, were soon opposed to the progress of our inquiries; and these obstacles were so multiplied, and made so vexatious, towards the end of February, that we conceived it would be both a waste of the public money, and a compromise of our own characters, to proceed." The Roman MSS., existing in the Museum of Naples, consist, in general, of papyrus, of a texture considerably thicker than that of the Greek MSS.; the characters, though much less perfect in formation, are also larger, and the rolls more voluminous. From the intermixture of Greek characters in some fragments of Latin MSS., and from the state of decomposition in which they were found, Sir H. thinks it extremely probable that some of them were of very ancient date. The ink with which they were written was a mixture of charcoal and glue; while the silence of Pliny as to ink composed of galls and iron renders it improbable that such a composition was used up to this period, and leads to the concluclusion that parchment and our present writing ink were adopted toge ther; " for a mixture of charcoal and solution of glue can scarcely be made to adhere to the skin, whereas the free acid of the chemical ink partly dissolves the gelatine of the MSS., and the whole substance adheres as a mordant." The most ancient parchment MSS. are probably the Palimpsesta, or Codices Rescripti, lately discovered by M. Angelo Mai, in the libraries of Milan and of Rome. Sir H. examined these curious and valuable MSS., particularly that which contains several books of Cicero's treatise De Republica, and which M. Mai refers to the second or third century. In these, time 1 has destroyed the vegetable of the ink, but the peroxide of iron remains, and M. Mai successfully employed solution of galls to revive its blackness. Sir H. made trial of different substances for restoring colour to the letters in ancient MSS. The triple prussiate of potash, used in the manner recommended by Sir Charles Blagden, with the alternation of acid, he found successful; but by making a weak solution of it with a small quantity of muriatic acid, and applying them to the letters, in their state of mixture, with a camel's hair pencil, the results were still better. After all, it is probable that we have sustained no great loss by the destruction of the Herculaneum MSS. It is remarkable that no fragments of Greek, and very few of Latin poetry, have been found in the whole collection. The sentences in which Mr Elmsley found a sufficient number of words to enable him to decypher their meaning, shew that the works of which these are the fragments, are of the same kind as those formerly examined, and belong to the schools of the Greek Epicurean philosophers and sophists. Sir H. concludes by remarking, that, should any new MSS. be discovered at Herculaneum, it would be desirable to have them immediately removed from the action of the air, by placing them in vases filled with carbonic acid. There can be no doubt, he thinks, that the more perfect specimens which have remained in the Museum, exposed, since the period of their discovery, about 60 years ago, to the action of the air, have undergone so great changes, as to render their entire unrollment nearly, if not altogether, impossible. On the 5th of April, a paper was read on the Separation of Iron from other Metals, by J. F. W. Herschell, Esq. The proposed basis of a rigorous separation of iron from the metals (manganese, cerium, nickel, cobalt,) not precipitated by sulphuriated hy. drogen, is a peculiarity in the peroxide of iron, in virtue of which it is incapable of subsisting in a neutral solution at the boiling temperature. If a solution of this peroxide be neutralized when cold, and then heated, a portion is deposited in the state of a subsalt, and the liquid becomes acid; if allow ed to cool, and again neutralized, a fresh portion of the metallic contents separates on re-applying the heat, and so on till the quantity held in solution is no longer sensible to the most delicate re-agents. If, on the other hand, the neutralization be performed while actually boiling, we attain this limit at one operation. Hence, Mr Herschell recommends the following process:Having peroxidized, by means of nitric acid, a solution containing iron, and any of the abovementioned metals, drop into it, while boiling, carbonate of ammonia, till the acid reaction is entirely destroyed, even going a little beyond the point of exact neutralization. The whole of the iron, to the last atom, is separated, while the liquid retains in solution the other metallic oxides, as well as the minute portion of their carbonates due to a trifling excess of the alkaline precipitant. In the cases of cobalt and cerium, the alkaline carbonate may be added in considerable excess, without separating any of the metals, and their solution, so freed from iron, is then a most delicate test of the presence of the latter metal. On the 31st of May, the reading of Mr Herapath's paper on Absolute Zero, (which had been commenced at a previous meeting,) was concluded. The object of Mr Herapath was to determine the law of temperature, and the point of absolute cold, or zero. For this purpose, he contrived an apparatus for obviating the effects of radiation; and having mixed equal weights of mercury at a very high and low temperature, he carefully ascertained the temperature of the mixture. In seven experiments of his own, thus made, and two of M. De Luc's, he found that the results followed a law, from which they differed, at a medium, not more than 1-10th of a degree. This law is, that the square of the temperature of a given portion of gas, varies as the elasticity and volume conjointly; and, therefore, when either continues the same, the temperature is as the square root of the other. Hence Mr H. found, that the heat of boiling water is to that of melting ice, as the 11 to the 8, or as 1.1726 to 1 nearly; and the point of absolute cold he also determines in a manner inde pendent of any theory of heat, from the principle of an air thermometer. In June nothing of any particular interest was communicated to the Society; and in July, the only paper we shall notice, was communicated on the 12th, and entitled, " On a New Compound of Chlorine and Carbon," by Messrs Phillips and Faraday. This compound was brought to England, and given to these gentlemen by M. Julin, of Abo, in Finland. It was formed during the distillation of green vitriol and nitre, for the production of nitric acid; is of a solid crystalline body, fusible and volatile by heat, without decomposition; is insoluble in water, but soluble in alcohol, ether, and essential oils; sinks in water; burns with a red flame, giving off much smoke, and fumes of muriatic acid gas; is not acted upon by acids; and gives out chlorine, and deposits charcoal, when its vapour is heated in a tube till decomposition takes place. Potassium burnt with it, forms chloride of potassium, and liberates charcoal.; its vapour, detonated with oxygen over mercury, forms carbonic acid, and chloride of mercury; passed over hot oxide of copper, it constitutes a chloride of copper and carbonic acid; and over hot lime, it occasions ignition, and produces chloride of calcium, and carbonic acid. It is composed of chlorine and carbon, and, from the experiments detailed, two parts appear to be formed of 1 portion of chlorine.. 44.1..33.5 2 portions of carbon.. 15.0..11.4 Hence it is a sub-chloride of carbon. All attempts to form it by other means have hitherto failed. After hearing another paper, by C. Bell, Esq., on the Structure and Functions of the Nerves, read, the Society adjourned till the usual period. THE ROYAL SOCIETY OF EDINBURGH, 1820-1. AFTER the usual adjournment, this subsequently discovered by MM. Biot Society resumed its sittings on the 15th and Seebeck in several fluids. M. Biot of November, 1819, when a paper, by had shewn, that, in some specimens of Dr Brewster, was read, on the subject rock crystal, a certain succession of of Circular Polarization, a name by tints was produced, by turning the which he proposed to distinguish the analyzing prism direct from right to phenomena first discovered by M. left, while, in other specimens, the Arago, along the axis of rock crystal, afterwards analyzed by M. Biot, and same succession was developed by turning the prism in a retrograde di rection, from left to right. He detected a similar difference in fluids; and he concluded that the cause of the phenomena resided in the ultimate particles of silex and the fluid, and was entirely independent of their mode of aggregation. The principal object of Dr B.'s paper was to describe the co-existence of the direct and retrograde structure in the same mineral, and the entire extinction of the circular polarization in the stratum which intervened between the two opposite structures. He discovered traces of circular polarization in crystals with two axes, and detected some new properties of this remarkable species of polarization. Several arguments were adduced to shew, in opposition to the opinion of Biot, that, in the case of crystals, or of solid bodies dissolved in fluids, the property of circular polarization cannot belong to the ultimate particles. Office-bearers and counsellors for the ensuing year were elected on the 29th. On the 6th of December a paper was read, containing further particulars respecting the celebrated slide at Alpnach, with a notice of its recent demolition. Referring, for full and satisfactory information, to Professor Playfair's interesting description of this remarkable work, which the reader will find in the recent edition of his works, we need only mention that this slide was formed upon the side of Mount Pilatus, in the canton of Unterwalden, by Mr John Rupp, engineer, for the purpose of bringing down the valuable timber, with which the mountain was covered, into the Lake of Lucerne, from which the conveyance to the German Ocean was easy and expeditious. It was constructed of about 25,000 large pine-trees, deprived of their bark, and united together in a very ingenious manner, without the aid of iron. It occupied 160 workmen during 18 months, cost nearly 100,000 francs, or 42504., extended about three leagues, or 44,000 English feet, and terminated in the Lake of Lucerne. It had the form of a trough, about six feet broad, and from three to six feet deep; its bottom was formed of three trees, the middle one of which had a groove, cut longitudinally, for receiving small rills of water, conducted into it from various places, for the purpose of diminishing the friction; and the whole of the slide was sustained by about 2000 supports, and in many places attached, in a very ingenious manner, to the rugged precipices of granite. The direction was sometimes straight, and sometimes zig-zag, with an inclination of from 10° to 18°; it was carried along the sides of hills, and the ranks, and sometimes the summits, of precipitous rocks; in some places it passed under ground, and in others was conducted over deep gorges by scaffoldings 120 feet in height. In the progress of the work the greatest difficulties were encountered and overcome by zeal and perseverance. When finished, it was found to answer every purpose for which it had been intended. Large pines, about 120 feet in length, and ten inches in thickness at their smaller extremity, darted through the space of three leagues in 21 minutes, and, during their rapid descent, appeared to be only a few feet in length. In order to shew the enormous force acquired by the trees from the velocity of their descent, M. Rupp made arrangements for causing some of them to spring from the slide. They penetrated, by their thickest extremities, no less than from 18 to 24 feet into the earth; and one of them having by accident struck against the other, it instantly cleft it through its whole length, as if it had been struck by lightning. After the trees had descended the slide, they were collected into rafts upon the Lake, and conduct |