formed, without the evolution of much heat; and ultimately much muriatic acid was produced, and two other substances, one a solid crystalline body, the other a dense thick fluid. It was found by further examination, that neither of these were soluble in water; that both were soluble in alcohol-the liquid readily, the solid with more difficulty. Both of them appeared to be triple compounds of chlorine, carbon, and hydrogen; but the author reserves the consideration of these, and of other similar compounds, to another opportunity.

Iodine appears to exert no action upon the substance in several days in sun-light; it dissolves in the liquid in small quantity, forming a crimson solution.

Potassium heated in the liquid did not lose its brilliancy, or exert any action upon it, at a temperature of 186°.

Solution of alkalis, or their carbonates, had no action upon it. Nitric acid acted slowly upon the substance, and became red; the fluid remaining colourless. When cooled to 32°, the substance became solid, and of a fine red colour, which disappeared upon fusion. The odour of the substance, with the acid, was exceedingly like that of almonds, and it is probable that hydrocyanic acid was formed. When washed with water, it appeared to have undergone little or no change.

Sulphuric acid added to it, over mercury, exerted a moderate action upon it, little or no heat was evolved, no blackening took place, no sulphurous acid was formed; but the acid became of a light yellow colour, and a portion of a clear colourless fluid floated, which appeared to be a product of the action. When separated, it was found to be bright and clear, not affected by water or more sulphuric acid, solidifying at about 34°, and being then white, crystalline, and dentritical. The substance was lighter than water, soluble in alcohol, the solution being precipitated by a small quantity of water, but becoming clear by great excess.

With regard to the composition of this substance, Mr. Faraday's experiments prove it a binary compound of carbon and hydrogen, two proportionals of the former element (6 x 2)=12 being united to one of the latter 1. The absence of oxygen is proved by the inaction of potassium, and the results obtained when passed through a red-hot tube.

Of the various other products from the condensed liquor, the next most definite to the bi-carburet of hydrogen appears to be that which is most volatile. If a portion of the original liquid be warmed by the hand, or otherwise, and the vapour which passes off be passed through a tube at 0°, very little uncondensed vapour will go on to the mercurial trough; but there will be found after a time a portion of fluid in the tube, distinguished by the following properties. Though a liquid at 0°, it, upon slight elevation of temperature, begins to boil, and before it has attained

32°, is all resolved into vapour or gas, which may be received and preserved over mercury.

This gas is very combustible, and burns with a brilliant flame. Its specific gravity was between 27 and 28, hydrogen being 1. Hence 100 cubic inches weigh nearly 57.44 grains.

When cooled to 0°, it condensed again, and enclosed in this state in a tube of known capacity, and hermetically sealed up, the bulk of a given weight of the substance at common temperatures was ascertained. This compared with water gave the specific gravity of the liquid as 0.627 at 54°. It is, therefore, among solids or liquids the lightest body known.

This gas, or vapour, when agitated with water, is absorbed in small quantities. Alcohol dissolves it in large quantity; and a solution is obtained, which, upon the addition of water, effervesces, and a considerable quantity of the gas is liberated. The alcoholic solution has a peculiar taste, and is neutral to test-papers.

Olive oil dissolves about six volumes of the gas.

Solution of alkali does not affect it; nor does muriatic acid. Sulphuric acid condenses the gas in very large quantity; 1 volume of the acid condensing above 100 volumes of the vapour. Sometimes the condensation is perfect, at other times a small quantity of residual gas is left, which burns with a pale blue flame, and seems to be a product of too rapid action. Great heat is produced during the action; no sulphurous acid is formed; the acid is much blackened, has a peculiar odour, and upon dilution generally becomes turbid, but no gas is evolved. A permanent compound of the acid with carbon and hydrogen is produced, and enters, as before mentioned, into combination with bases.

By detonation with oxygen it appears that 1 volume of the vapour or gas required 6 volumes of oxygen, consuming 4 of them in producing 4 of carbonic acid gas, and the other 2 by 4 of hydrogen to form water. Upon which view, 4 volumes or proportionals of hydrogen 4, are combined with 4 proportionals of carbon 24, to form one volume of the vapour, the specific gravity of which would, therefore, be 28. Now, this is but little removed from the actual specific gravity obtained by experiment.

As the proportions of the elements in this vapour appear to be the same as in olefiant gas, it became interesting to ascertain whether chlorine had the same action upon it as on the latter body. Chlorine and the vapour were, therefore, mixed in an exhausted retort: rapid combination took place, much heat was evolved, and a liquor produced resembling hydro-chloride of carbon, or the substance obtained by the same process from olefiant gas. It was transparent, colourless, and heavier than water. It had the same sweet taste, but accompanied by an after aromatic bitterness, very persistent. Further, it was composed of nearly

It

equal volumes of the vapour and chlorine it could not, therefore, be the same as the hydro-chloride of carbon from olefiant gas, since it contained twice as much carbon and hydrogen. was, therefore, treated with excess of chlorine in sun-light: action slowly took place, more chlorine combined with the substance, muriatic acid was formed, and, ultimately, a fluid tenacious triple compound of chlorine, carbon, and hydrogen was obtained; but no chloride of carbon. This is a remarkable circumstance, and assists in shewing, that though the elements are the same, and in the same proportions as in olefiant gas, they are in a very different state of combination.

Mr. Faraday next proceeds to detail the experiments by which he ascertained the tension of the most volatile part of the condensed oil gas liquid; it appears to be equal to about 4 atmospheres at the temperature of 60°. He also adverts briefly to the properties of the other portions of the liquor, and gives an outline of such facts as others have determined respecting them. In conclusion, he observes, that the importance of these vapours in oil gas, as contributing to its very high illuminating powers, will be appreciated, when it is considered that with many of them, and those of the denser kind, it is quite saturated. On distilling a portion of liquid, which had condensed in the pipes leading to an oil gas gasometer, at Apothecaries' Hall, he found it to contain portions of the bi-carburet of hydrogen. It was detected by submitting the small quantity of liquid which distilled over before 190° to a cold of 0°, when the substance crystallized from the solution. It is evident, therefore, that the gas from which it was deposited must have been saturated with it. On distilling a portion of recent coal gas tar, as was expected, none could be detected in it, but the action of sulphuric acid is sufficient to shew the existence of some of these bodies in the coal gas itself.

With respect to the probable uses of the fluid from compressed oil gas, it is evident, in the first place, that being thus volatile, it will, if introduced into gas which burns with a pale flame, give such quantity of vapour as to make it brightly illuminating; and even the vapour of those portions which require temperatures of 170°, 180°, or higher, for their ebullition, is so dense as to be fully sufficient for this purpose in small quantities. A taper was burnt out in a jar of common air over water; a portion of fluid boiling at 190° was thrown up into it, and agitated; the mixture then burnt from a large aperture with the bright flame and appearance of oil gas, though of course many times the quantity that would have been required of oil gas for the same light was consumed: at the same time there was no mixture of blueness with the flame, whether it were large or small.

The fluid is also an excellent solvent of caoutchouc, surpassing

every other substance in this quality. It has already been applied to this purpose.

It will answer all the purposes to which the essential oils are applied as solvents, as in varnishes, &c., and in some cases where volatility is required, when rectified it will far surpass them.

It is possible that, at some future time, when we better understand the minute changes which take place during the decomposition of oil, fat, and other substances by heat, and have more command of the process, that this substance, among others, may furnish the fuel for a lamp, which remaining a fluid at the pressure of two or three atmospheres, but becoming a vapour at less pressure, shall possess all the advantages of a gas lamp, without involving the necessity of high pressure.

xii. Account of the repetition of M. Arago's experiments on the Magnetism manifested by various substances during the act of rotation. By C. Babbage, Esq. F.R.S., and J. F. W. Herschel, Esq. Sec. R.S.

Though this paper is merely stated to refer to a repetition of M. Arago's experiments, it may in fact be considered as a distinct and somewhat elaborate investigation founded upon a report of the very singular results obtained by that celebrated physical inquirer. Having already laid before our readers an outline of its contents, and intending, upon an early occasion, to give a connected view of the very singular discoveries in magnetism which every day is bringing forth, we shall at present merely recommend those who are experimentally engaged on the subject, to study Messrs. Babbage and Herschel's paper.

xiii. On the Magnetism developed in Copper and other Substances during rotation. In a Letter from Samuel Hunter Christie, Esq., M.A., &c., to J. F. W. Herschel, Esq., Sec. R. S. municated by J. F. W. Herschel, Esq.

Com

xiv. On the Annual Variations of some of the principal fixed Stars. By J. Pond, F.R.S. Astron. Royal.

xv. On the Nature of the Function expressive of the Law of Human Mortality, and on a new Mode of determining the Value of Life Contingencies. In a Letter to Francis Baily, Esq., F.R.S. &c. By Benjamin Gompertz, Esq., F.R.S.

In respect to these which are the concluding papers of the

volume before us, our limits prevent any more extended notice than that already given in our abstract of the proceedings of the Royal Society, (Vol. xix. p. 277.)

II. Considerations on Volcanoes; the probable Causes of their Phenomena, the Laws which determine their march, the Disposition of their Products, and their connexion with the present State of, and past History of the Globe; leading to the establishment of a New Theory of the Earth. By G. Poulett Scrope, Esq., Sec.

Geol. Soc. London, 1825. Phillips.

THIS work forms what is commonly called a complete treatise, though the author has given it a more moderate title; and although, like every work on geology, it cannot fail to contain disputed points and controversial matter, we do not know that any thing new can now be said on these subjects, and shall not therefore indulge ourselves in discussing them. Thinking it equally unnecessary to enter into any discussion on the merits of the work, as such, since, on all subjects which, like this, may be called technical, the particular readers into whose hands it must fall, are fully as competent to judge of it as ourselves, we shall be content with giving such an analysis of it as is practicable, conceiving, that in so doing, we shall be best able to gratify and interest our readers.

Describing generally what is meant by volcano, and by lava, in which the author properly includes all volcanic rocky erupted matter, under whatever form it may be disposed on the surface, Mr. S. proceeds to state the known volcanoes at 200; afterwards showing reason to think this to be much less than the number probably existing in the world. The arguments for this opinion consist in our ignorance of the interior of great continents, in the probability of unknown marine volcanoes, and in the fact that, for want of observers and records, many which have broken out at distant times, are unknown or forgotten.

To the terrestrial volcanoes he has given the term subaërial, and to the marine the appellation of subaqueous.

In the first class, the character of the appearances vary according to the incidental fact of the volcano being new, or appearing through an ancient vent. But it is not very certain that we know of any rigidly new; as even the eruptions of Yorullo are considered as coming from vents subsidiary to former ones. Auvergne, however, and the well-known country connected with it, in this respect, as well as the volcanic territory of the Rhine, preserve the records of volcanoes which have been once of this character, and where therefore the circumstances can be studied with facility.