method of distinguishing certain organic compounds by observing their respective effects upon polarized light, and having exhibited an apparatus constructed for the illustration of this new method of analysis, Prof. Powell rose, and explained briefly the principles upon which this investigation proceeded, by stating the laws of plane and circular polarization. It appears that, whilst sugar derived from the cane deflects the polarized ray to the right, that obtained from honey or pure starch causes a deviation to the left; and the amount of deflection in a given sample will vary with the relative proportion of the different kinds of sugar.-Athenæum.

CHEMICAL VIEWS REGARDING THE FORMATION OF ROCKS.

PROF. NEPOMUK FUCHS, in some elaborate "Chemical views regarding the Formation of Rocks, which seem to afford new arguments in favour of Neptunism," having briefly investigated the siliceous, calcareous, and carbonaceous series, considers the accompanying collateral and intermediate geological events. During the crystallization, the pasty or semi-solid masses must have been contracted into smaller space. The consequence of this must have been the formation of rents and fissures into which the existing amorphous mass penetrated, and in which it would freely crystallize; and, in this way, veins were formed, as, for example, those of granite. In a similar manner, great caverns and empty spaces were produced; and this caused sinkings and fallings-in, by which strata were dislocated, had their original position altered, and acquired the appearance of having been elevated. Sinkings of masses of rock also produced valleys and ravines, besides circular hollows in which water was collected, some of which still remain, and others were broken through. By means of earthquakes, the falling-in of caverns, and the bursting of lakes, huge masses of debris were formed, which became the sport of the waters, whose power was often combined with that of hurricanes and violent rains. Great devastation was produced by such agencies, assisted by volcanoes.

During such prodigious processes as those by which the earth and atmosphere were formed, the imponderables must have been in very active operation; sometimes assisting in forming, and sometimes in destroying what had been already formed. The electrical meteors, more especially, must have acted with a vigour and power, of which no conception can be obtained from their present displays. Since, even at present, lightning sometimes shatters rocks, and melts quartzose sand, we may believe that, at such a time, the electrical masses of fire descending from the heavens, may have vitrified rocks, and caused actions in the depths of the earth, of such a nature as to lead to the belief that they were produced by subterranean fire. Since, even at the present day, water-spouts uproot the strongest trees, and remove them far from their original situations; we may conceive water-spouts, of the period we have been discussing, powerful enough to remove large fragments of rock from their beds, and to convey them to remote regions, where we are now surprised to find such strangers. Lastly, we ought not to judge of the scale on which such

operations proceeded at these early periods of the world's history, from what we observe now taking place on the surface of our globe.Compiled and curtailed from Leonhard's Jahrbuch, and the Munich Galehrte Anzeigen; in Jameson's Journal; No. 51.

CLASSIFICATION OF SOILS.

M. DE GASPARIN has presented to the French Academy of Sciences a memoir on this important subject; which is the first part of a work upon Agronomy, or that branch of the science of Agriculture which has for its object the study of soils; their susceptibility and relative value being reserved for another publication. We must, however, confine ourselves to the following facts, which result from M. De Gasparin's investigation:

1. A small quantity of carbonate of lime is sufficient to change the character of soils. The 5 or 6 per cent. of this substance which is supplied by marling, produces very remarkable effects; whilst the 100th part, which is contained in the soil of Lille, as analyzed by M. Berthier, likewise sensibly affects its nature and vegetative power. Lime gradually disappears from soils, being changed into a bi-carbonate. The enclosure of La Grande Chartreuse, which is formed of the debris of rocks containing lime, does not now furnish a single particle of this earth.

2. The carbonate of magnesia modifies soils in the same way as carbonate of lime.

3. It has often been attempted to ascertain the characters which distinguish those soils in which gypsum produces an effect upon vegetables, and those in which it has none; but hitherto without success. The author has ascertained that gypsum has no action upon recent alluvial soils, and that it is beneficial for all more ancient soils, beginning with the diluvian.

4. He has found sal-ammoniac in all the clays belonging to the vegetable stratum of soils; thus showing the importance of clay as a magazine of the materials which favour vegetation.

5. If by washing we separate into several portions the coarser and finer parts of earth, we find that the tenacity of such soil is in proportion to the quantity of the latter kind, except in a small number of cases.

6. Upon examination with the microscope, it is ascertained that these exceptions are owing to a coating of ferruginous clay which adheres to the surface of the mineral particles, that washing separates it with difficulty, and that it serves as a cement, forcibly agglutinating, and increasing the tenacity of the whole.-Jameson's Journal.

CHEMICAL THEORY OF VOLCANOES.

PROF. DAUBENY, in reply to Prof. Bischof's objections to his Chemical Theory of Volcanoes, sums up with the following enumeration of phenomena of constant occurrence, which follow directly from the principles of his views:

1. The evolution of sulphuretted hydrogen, in quantities far exceeding what are to be explained by the re-action of carbonaceous matter upon sulphates, or any of those other processes which sometimes produce it on the surface of the earth.

2. The disengagement of sal-ammoniac; for, although one of the constituents of this compound, the muriatic acid, might arise from the decomposition of sea-salt by aqueous vapour, the other one, the ammonia, implies the presence of free hydrogen as well as of nitrogen gas, near the focus of the volcanic action.

3. The circumstance which Dr. Daubeny has substantiated in so many cases that he begins to believe it almost universally true, is that the atmospheric air exhaled from volcanoes, and, indeed, generally from the interior of the earth, is deprived in a greater or less degree of its proper proportion of oxygen. That processes, therefore, by which this principle is abstracted, are going on extensively within the globe cannot be denied; and hence Dr. Daubeny conceives that any theory which attempts to account for volcanic action without taking notice of so essential a phenomenon, ought to be regarded as imperfect and unsatisfactory.-Jameson's Journal.

Dr. Daubeny, in a note to the preceding Memoir, adds: "that with regard to the precise nature of the chemical processes which give birth to volcanoes, he has always studiously distinguished between the degree of probability belonging to that part of the hypothesis in question which asserts the fact of the general absorption of oxygen gas throughout the interior of the globe, and that which undertakes to explain the latter phenomena, by supposing certain bodies, capable at once of decomposing water, and of combining with its oxygen without eliminating a volatile product, to exist in the spots at which the action originates. Whatever difficulty there may be in imagining the earthy and alkaline metalloids to exist among the number of these bodies, that difficulty will, at least, not be enhanced by supposing them to be as generally distributed as the phenomena themselves appear to warrant us in supposing. If it be once granted, that potassium and soda contribute, by their combustion, to feed the fires that glow between Vesuvius and Etna, there seems no reason why we should refuse to believe that the same substances may be present, wherever the most waters or earthquakes indicate a similar train of phenomena.-Jameson's Journal, No. 53; abridged.

CHEMICAL POWERS OF LIGHT.

M. EDMUND BECQUEREL has communicated to the French Academy of Sciences some important investigations on the Chemical Powers of Solar Light, which will probably lead to new and valuable results. It has been long known that light has the power of variously affecting certain chemical compounds; sometimes causing combination between two elements, and in other cases effecting the decomposition of compound substances; and it has been found that, when a pencil of light is decomposed by passing through a prism of glass, those rays which possess this power are differently refracted from the coloured rays; and hence the existence of peculiar rays, to which the name of chemical rays is given, has been deduced. The chief difficulty in experiments on these rays has been the slow nature of the actions caused, and the difficulty of appreciating them. M. Becquerel has overcome these sources of uncertainty, and is enabled to study the chemical power of light with ease, and measure the effects produced with considerable accuracy. The manner in which this is done is very simple. Two liquids of different densities, but both conductors of electricity, and of such a nature as to act chemically upon each other when exposed to the influence of solar light, are selected; and a portion of both is put into a cylindrical vessel blackened on the exterior. A plate of platinum is placed in the denser of the two fluids, and another similar plate is also immersed in the lighter liquid; these plates being then connected by means of platinum wires with the two terminations of a very delicate galvanometer, the apparatus is complete. If when thus arranged, a ray of light is suffered to pass through the mass of fluid, it causes chemical action to take place at the surface of contact between the two liquids, and a current of electricity which this sets in circulation is immediately rendered evident by the galvanometer. As the angle of deflection of the galvanometer indicates the power of the electric current, and as that is in exact proportion to the chemical action which originates it, it is evident that this arrangement gives an accurate measure of the power of the chemical rays of light, at different times, from different sources, and under various circumstances. M. Becquerel details some experiments on the quantity of these chemical rays, which is intercepted when a ray of light is made to pass through screens of different substances, such as rock crystal, mica, and variously coloured glasses; and states that he is still engaged in experimenting on the subject.-Athenæum.

COLOURED FILMS PRODUCED BY ELECTRO-CHEMICAL AGENCY AND BY HEAT.

MR. WARINGTON has communicated to the Philosophical Magazine, No. 100, a paper upon this interesting inquiry, which is intended as a reply to a memoir by the late Prof. Nobili on the subject; the translation of which appeared in the Scientific Memoirs, vol. i., p. 94, under the title of a "Memoir on Colours in general, and particularly on a new Chromatic Scale deduced from Metallochromy, for scientific and practical purposes."

We have not space for the details, but quote the summary of this valuable contribution. The author infers: 1st, that the appearances called electro-chemical are not films of oxygen and acid, but lead in a high state of oxidation, thrown down on the surface of the metal by means of a voltaic combination acting through a medium formed by a solution of acetate of lead; 2ndly, that these colours owe their varied tints to the varying thickness of the precipitated film, and that the light is reflected through them from the polished surface of the metallic below; 3rdly, that the colours produced on the surface of metals by the application of heat are owing to the formation of thin films of oxide on the metal, in consequence of exposure to the air during the process; that this does not involve the necessity of any one oxide being always formed, as this must vary according to the affinity of the metal used for oxygen, under the influence of a raised temperature;

4thly, that the opacity of the metal is not in the slightest degree an argument against the transparency of the oxide; and we have, both in nature and art, numerous cases which place this question beyond a doubt; 5thly, that we can produce analogous appearances by substituting other elements for oxygen, such as iodine, chlorine, bromine, sulphur, phosphorus, carbon, &c.

COLOUR OF BLOOD DURING COAGULATION.

DR. P. K. NEWBIGGING, in a paper read before the Royal Society of Edinburgh, on April 15, describes certain anomalous appearances presented by venous blood when left in contact with coloured porcelain. When blood drawn from a vein is either allowed to coagulate in a porcelain cup, or after coagulation is left in it for some hours, the dark purple tint, characteristic of venous blood, is found to be altered to the bright arterial hue, wherever it was in contact with any elevated degree of the green colour, which is communicated by means of the protoxide of chrome; and in one instance only, the same effect was produced by a device of a crimson tint. The author cannot refer this effect to the porcelain being of raised pattern, adhesion of oxygen to its surface, or to any peculiar change of the molecules of the blood: he, therefore, merely records the fact, adding that "the change of colour which takes place seems identical with the florid hue occasioned by arterialization of the blood from ordinary causes." -Jameson's Journal.

VINOUS FERMENTATION.

On June 6 was read to the Royal Society a series of "Experiments on the Chemical Constitution of several bodies which undergo the Vinous Fermentation, and on certain results of the Chemical Action:" by R. Rigg, Esq. The special object of this paper is to show, Ist, that sugar is not constituted of carbon and water only; 2dly, that during the vinous fermentation, water is decomposed; 3dly, that neither pure carbonic acid nor alcohol, in the common acceptation of the term, is the product of this chemical action; and, 4thly, that fermented liquors owe some of their valuable qualities to peculiar products formed during fermentation. These views are confirmed, not merely by direct experiments, but likewise by other changes which fermented liquors undergo on being kept under circumstances favourable for farther chemical action; and the author having proved the existence of a compound of carbon, hydrogen, and nitrogen, and shown that water is decomposed during its formation, he thinks we are enabled to account for many other changes which occur during the decomposition of vegetable matter and the growth of plants: whence he proceeds to show that evidence of the presence of such a compound as the above in fermented liquors is afforded by the changes which take place in consequence of keeping them. In accounting for many of the phenomena of the vinous fermentation, the small excess of oxygen found in all these compounds, which undergo this chemical action, is an essential and indispensable circumstance; a conclusion which is corroborated both by the formation of these new compounds which have been described, and by the generation of the acetic, tartaric, or oxalic acid