I was led into the following train of investigation from observing, that, when minute quantities of certain substances were dissolved in alcohol, and the liquid was acted on by a moderate voltaic power, evident signs of decomposition were exhibited by the evolution of elastic fluid at the negative pole. In investigating the nature of the changes produced, I was farther led to examine the action of voltaic electricity on a variety of alcoholic solutions, and also the agency of more powerful galvanic batteries on pure alcohol and on ether; and, ultimately, I was conducted into a field, into which I should have hesitated voluntarily to enter, namely, the voltaic decomposition of aqueous solutions, which has recently been investigated with so much success by a distinguished cultivator of science. In the following paper, it will be my object to give some account of the experiments which I have made on these different subjects, and of the results and views to which I have been led.

The many irregularities to which the vibrations of the horizontal needle are subject, renders the usual method of investigating the terrestrial magnetic intensity, although precise in theory, occasionally uncertain in practice. It has been my endeavour in the following paper, to consider in some measure the most prominent of the causes of these irregularities, with a view of arriving at certain practical deductions, by means of which they may be either greatly palliated, or otherwise avoided.

For a long time I was anxious to know the rate of expansion of the common building-stone of this neighbourhood, as it is not given in any of the tables of the expansions of substances, because I have sometimes thought that the vertical cracks frequently seen intersecting rubble walls might arise from the contraction caused by a diminution of temperature. During a long-continued and severe frost which occurred in 1826, I thought the rents in a considerable stretch of wall, which I passed at all seasons, appeared more open than usual. This, however, was merely conjectural, and I paid no more attention to the subject until 1830, when, as I mentioned in a notice on the commencement of my experiments read at the meeting of the British Association in September last, an interdict of the Dean of Guild Court of Edinburgh rendered the rate of expansion of stone a matter of more importance than merely a curious philosophical speculation.

Although the phenomena of the Pyro-Electricity of Minerals, as it has been termed, and those of the Tourmaline in particular, have, after a long period of neglect, been recently studied by more than one philosopher of eminence, there are a sufficient number of undetermined or debatable points, even at the threshold of the inquiry, to yield facts of novelty and interest to those who will take the trouble to look for them.

Having during the past summer been much engaged in studying the relations of bodies to heat and electricity, I was induced, by having in my possession a considerable number of long tourmalines, to repeat and endeavour to verify some recently published experiments with this mineral. These inquiries brought out several new facts; and, with the hope of adding something to our knowledge in this curious field, I have taken this opportunity of communicating to the Society the results of some very recent experiments.

Among persons interesting themselves in the progress of British manufactures, it can scarce fail to be known, that Mr Neilson of Glasgow, manager of the Gas Works in that city, has taken out a patent for an important improvement in the working of such furnaces as, in the language of the patent, “are supplied with air by means of bellows, or other blowing apparatus.” In Scotland, Mr Neilson's invention has been extensively applied to the making of cast-iron, insomuch that there is only one Scotch iron-work where the invention is not in use, and in that work, apparatus is under construction to put the invention into operation.

The country in which Edinburgh is situated has no great elevation above the level of the sea, presenting a gently undulating surface, except where hills of igneous origin, in groups, or perfectly insulated, rise abruptly through the strata, which consist of the sandstones and shales of the coal-formation, with occasional beds of limestone, which they overlie, and this country is more or less covered by old and new alluvial deposits.

The views suggested by these hills to the penetrating genius of Hutton, who may be justly considered the founder of modern geology, first led to the knowledge of the true nature and origin of the trap-rocks. Their analogy to those produced by existing volcanoes, and the phenomena observed in their relations with the secondary strata, leave no doubt as to their having been poured out from the interior of the earth in a fluid or viscid state, through fissures in the strata occasioned by subterranean convulsions—not, however, in the open air, like currents of lava from recent craters, but in sheets or masses at the bottom of the sea, their cooling and consolidation having evidently been slow and gradual, under great pressure, such as might be produced by a large volume of superincumbent water, as was ably illus trated by the experiments of the late Sir James Hall; or by their having been originally formed as dykes, at considerable depths, either below or among the strata.

Some time ago a mineral was put into my hands by Mr Rose, the intelligent mineral dealer of this city, the nature of which was not known, although it had been conjectured to be a variety of Mesotype. Mr Rose obtained it from Count Vargas Bedemar of Copenhagen, who brought it from the Faroe Islands, and subsequently visited this country some years ago. A short chemical examination soon satisfied me that it differed entirely from mesotype; and having ascertained that it contained silica, lime, water, and potash, and no notable quantity of alumina, I was led to conjecture that it would prove to be a variety of apophyllite, although, in that view, it would have presented very remarkable deviations from the ordinary structure of that mineral.

Few poisons are of greater interest, in a historical or scientific point of view, than Hemlock. It has been known ever since the most classic periods of antiquity, being generally believed to have been the ϰωνϵιον of Nicander and Theophrastus, and commonly thought to have been the poison with which state-criminals were despatched in ancient Athens. Since that period it has occupied a prominent place in all works on Toxicology; and it has been immemorially familiar as a deadly poison to the vulgar in every part of Europe, where there is scarcely a country or even a province which does not produce it in abundance. For nearly a century, too, since the writings of Baron Storck of Vienna in 1762, it has been constantly in the hands of the physician as a remedy, and has been currently employed at different times in the treatment of some of the most common, as well as in some of the most malignant, of all the maladies to which the human body is liable.

The power of making such a representation of any object, as shall give a distinct idea of its form, is a faculty which artists possess in different degrees of perfection. The principal difficulty is, to get a first delineation of any subject; from this a copy may be made in various ways, with less exertion of talent than was required for the composition of the original.

Various geometrical and optical inventions have been proposed to assist the artist in making an outline of an object which he wishes to represent. The Reticulated Square and other contrivances, for placing every point of the thing to be represented in its proper place in the picture, belong to the first class; the Camera Obscura and the Camera Lucida to the second. When a design is to be copied, a different kind of contrivances will in general be more convenient. It is only of these that I propose to treat here.

Probably no department of Analytical Mechanics presents greater difficulties than that which treats of the motions of fluids; and hitherto the success of mathematicians therein has been comparatively limited. In the theory of the waves, as presented by MM. Poisson and Cauchy, and in that of sound, their success appears to have been more complete than elsewhere; and if to these investigations we join the researches of Laplace concerning the tides, we shall have the principal important applications hitherto made of the general equations upon which the determination of this kind of motion depends.

The Society has lately been delighted with the discovery of organic remains in our vicinity, which prove, that, at some distant period of unrecorded time, the fertile plains of Mid-Lothian must have furnished food and habitation to beings very different from those which now draw life and enjoyment from their productions. Yet it must be regretted, that, in the conclusions derived from the existence of such remains (with the exception of a few general principles, leading us to regard with deeper feelings of awe and reverence Him who has made all things so wonderfully and fearfully), we have little with which we can sympathise, and still less that can link our existence with that of those of which we see nothing but these imperishable monuments. I confess, however, with the partiality naturally felt by every man for that study to which he may have principally devoted his time and attention, that I regard with far deeper feelings those fleeting sounds—those επεα π˥εζοεν˥α—which, after passing from lip to lip uninjured during the lapse of so many ages, are, when carefully examined, found to have been component parts of those languages, falsely denominated dead, and which can be usefully adduced in illustration of the written records of those mighty spirits who have as yet as far surpassed us in the science of mind, in the purity of their taste, and the perfection of language, as we have surpassed them in the severer sciences—in unfolding the mysterious powers of matter—in discovering the laws according to which they operate—and in subjecting them to the dominion of man. It is with these feelings, and also from a wish to contribute to the great work now so admirably carried on by the German scholars, and by some distinguished fellow-labourers in this country, that of uniting the present and the past, the remote and the near, by proving the consanguinity of the great Caucasian branch of the human family, that the following statement has been drawn up on the force of the Latin particle ve or (as it was written by the more ancient Romans) vae.

The few facts we possess relative to the chemical agency of atmospheric electricity, and a certain degree of obscurity connected with these facts, as pointed out by Mr Faraday, in commenting on the late Mr Barry's results, published in the Philosophical Transactions for 1831, have induced me to institute some experiments on the subject, with the hope of acquiring additional information.

Reflecting on the manner in which, in certain instances, the great experiment of Franklin, in apparent proof of the identity of common and of atmospheric electricity, had been repeated, especially in our own country; reflecting also on the experiments of M. Colladon on atmospheric electricity, made by means of a lightning-conductor,—it appeared to me not improbable that results might be witnessed of some interest by substituting for an electrical kite, the means employed by Mr Barry, an insulated wire raised a few feet above the summit of any building of moderate height.

Few substances have been made the subject of experimental inquiry more frequently than the compounds of phosphorus and hydrogen, and no subject is so remarkable for the various and conflicting results which it has presented to chemists of the greatest acuteness and practical skill. The obscurity which long hung over the subject has been dispelled, however, in a great measure, by the recent investigations of Henry Rose of Berlin. Although baffled in his early researches, that philosopher returned again and again to the subject, and at last succeeded in determining the chemical functions and true constitution of phosphuretted hydrogen. He has shewn it to be analogous to ammonia in chemical character and composition. But hitherto two compounds of phosphorus and hydrogen had generally been admitted to exist, which were believed to differ in composition, as they do in properties, one being spontaneously inflammable in atmospheric air, and the other not so. Rose establishes beyond all doubt that these gases are essentially of the same composition, and of the same specific gravity; and, indeed, that they are mutually convertible, each into the other, without any addition or subtraction of matter that could be perceived. In explanation of their possessing different properties, under the same composition, allusion is made by Rose to Isomerism, or the doctrine that two bodies may exist identical in composition, but differing in properties. Certainly the existence of two gases, constituted alike, and yet possessing different properties, if established, would afford a firm basis for this doctrine.

1. The first series of these researches, in the exact form in which they are printed, were laid before the Royal Society on the 19th January 1835. The whole of the experiments there described were made, and the paper written and printed, within a space of time little exceeding two months. This haste, unfavourable to composition, I considered as a less evil than postponing for a period of time, which must have been considerable, the publication of a class of facts which might be said almost to embrace a new science. The professional duties which pressed upon me during the whole continuance of those experiments, then called imperatively on my attention, and during the remainder of the Session my time was devoted to them. The summer I devoted to a foreign excursion, some of the results of which I afterwards digested; and it was not till the commencement of the winter session which has just closed, that I prepared, with a fresh stock of health and spirits, to reinvestigate the whole subject of the Polarization of Heat, and to assign numerical values to the effects, whose existence I had before been contented to prove.

In entering on a question which may be said to occupy a portion of the debateable land between Physiology and Metaphysics, it seems, in the first place, necessary to state with precision the nature of the difficulty, which has long been felt on this subject, and endeavour to determine the degree to which it is reasonable to expect, that this difficulty may be removed; and on these points there is such a discrepancy of opinion, even among the latest and most esteemed authors, as obviously to make farther inquiry desirable.

No one can be more thoroughly convinced than I am, of the utter futility and absurdity of all attempts “to shoot the gulf which separates the sensible world from the sentient soul.” In all our inquiries in the Physiology of the Nervous System, as connected with mental acts, we must keep in mind, that the end of these inquiries can only be, to determine the physical conditions under which the different mental phenomena take place; and those under which, when they have taken place, they affect the different organs of the body. The question, how it comes about, that when those conditions are fulfilled, these results follow, must be held, in every case, to be beyond our powers.

There is perhaps no geological problem of greater interest than that by which the conditions of the globe, in respect to the distribution of land and water, at the epoch of the coal formation, might be determined, if the necessary data for its solution could be obtained. We possess sufficient evidence to shew that, since that period, most of the continents and islands of the present day have been elevated above the waters, under which they were originally formed; but such proofs are altogether wanting when we endeavour to restore, in imagination, the probable extent of the older formations that might then have existed as dry land, but which now lie buried in the depths of the ocean, or have since been covered by an accumulation of more recent deposits.

Payne Knight, no mean name among philologers, after a masterly and convincing proof, that neither Zenodotus nor Aristarchus, the great critics of the Alexandrian school, could be acquitted of the charge of “scarcely credible ignorance” of the primitive form of the Homeric language, thus proceeds :—

“The grammarians and critics of Alexandria were all guilty of the same fault. They never investigated the original sources of the language, but classed among anomalous dialects and poetic licenses every thing that was not in unison with their own usual style of speaking. In their age there existed many clews to the inquiry, which have now disappeared, but which, at that time, might easily have been found in written records, and in the rude and semi-barbarous languages of Italy and other countries adjacent to Greece. Had any one, however, suggested to Aristarchus that the true form and character of the Homeric dialect was to be extracted from the Latin, Tuscan, or Oscan languages, he would in my opinion have been as much astonished as if he had heard of the claims of the Irish antiquary, who affirmed that the Homeric poems had been translated furtively from the “Gaelic into Greek.”

At the close of the preceding session, the Council of the Society did me the honour of entrusting me with the chemical examination of several articles sent not long ago to the Society by Mr Swinton, Secretary to Government at Calcutta. The articles in question are, 1. Specimens of the black varnish used in different parts of Hindostan and the Burmese territories, with specimens of the juices of which these varnishes are said to be compounded; 2. Specimens of naphtha from Persia, and of petroleum from Rangoon; 3. Specimens of wood-oil, a variety of fluid turpentine; 4. Specimens of crude caoutchouc, and of solutions of it in wood-oil.

The only one of these articles which has hitherto yielded results of such interest as to induce me to lay them before the Society, is the petroleum of Rangoon, which appears to contain a compound inflammable principle hitherto unknown.

In the month of August 1830, Reichenbach published his first memoir on the products of the destructive distillation of organic bodies, in which he described a new principle, to which he gave the name of Paraffine, as constantly occurring among those products. Not long after, in 1831, Dr Christison read before this Society a paper, in which he described a substance contained in the petroleum of Rangoon, to which he affixed the name of Petroline. On comparing the properties of these two substances, it was found that they agreed so nearly, that no doubt could be entertained that they were one and the same. As the priority of discovery rests with Dr Reichenbach, the name of Paraffine is now generally adopted. The properties of paraffine are as follows:—It is white, tasteless, inodorous, rather tough, lighter than water, fusible at 125° or 130° F., and it distils unchanged at a higher temperature. It resists the action of the strongest acids and alkalies; and, finally, when pure, it burns with a bright flame without smoke. In a second memoir published by Reichenbach in 1831, he described another of the products of destructive distillation, under the name of Eupione.