igneous rocks of the Auvergne, spread in black octohedral crystals in the fissures and small cavities. It is also found in the detritus from the disintegration of these rock masses.

The analysis of this mineral is, as given by M. Pisani :—

Alumina

Ferric Oxide

Ferrous Oxide
Magnesia

which gives the formula MgO Fe 0, Alo O Fe' 0".

59.06

10.72

13.60

17.20

This composition is that of a true Pleonaste, which is a black variety of the Iron and Magnesia Spinelle. But this variety is rendered remarkable by its crystalline form-an octohedral pyramid -which has not until now been recognized in any of the Spinelles.

Some remarkable discoveries of Native Lead have been made lately in Victoria, Australia. It is found associated with gold and oxide of iron in the gold drifts, under the basalt, and in the neighbouring veins containing Galena. Specimens have been forwarded to Mr. R. Brough Smyth, the Inspector of Mines at Melbourne. The first samples were from a "lead" at Mount Greenock, near Talbot, where they are said to be numerous. The second series of specimens came from the main "lead" at Aorca, where they are obtained from nearly every part of the "wash dirt." Mr. R. Brough Smyth informs us that, when carefully analyzed, he intends to forward the specimens, with a description, to the Geological Society.

From one of the journals published at Auckland, we learn of a valuable discovery of Bismuth in New Zealand. This metal is associated with copper, and by some novel process, it is said, the copper and the bismuth are economically separated from each other.

The production of the diamond by artificial means is once more attracting attention. M. de Chancourtois, in a paper read before the Academy of Sciences of Paris, announces that he has obtained, in a little more than twenty years, small crystals of diamond, by very slowly decomposing sulphide of carbon, by tin excited by a very weak electrical current. M. Elie de Beaumont has made a communication on the subject to the Academy.

Professor A. H. Church communicates to the Chemical News' the discovery of chloropal abundantly in a quarry close to the old tin mine of Carclase. "The chloropal occurs with Fluor in the fissures of the granite, and resembles that variety of chloropal which has been termed " gramenite," from Menzenberg near Bonn."

In 'L'Institut' for June is an interesting paper by M. Goebel, "Researches on the Carnalite, and upon the Red Coloration of certain Minerals." This paper was read before the Academy of Sciences of St. Petersburg. We must refer our readers to the original,

as it will not bear abstracting. Professor Shephard, in 'Silliman's Journal,' vol. xl., p. 110, announced the discovery of a new mineral Syhedrite, and L. S. Inglestrom, in the Journal fur Praktische Chemie,' vol. xcvii., writes of Kondro-Arsenite as a new mineral, but this requires confirmation.

METALLURGY.

Mr. C. Cochrane, of Dudley, has patented a process for separating dust from the gases evolved from blast furnaces. This in many cases is so great as to considerably interfere with the economical application of those gases. Mr. C. Cochrane proposes to construct a cylindrical chamber into which the gases pass, entering at the upper end, and descending and passing off at the lower end, of such chamber. In this chamber are numbers of parallel partitions, so arranged as to come below the open spaces in the partitions above. By passing through those partitions, the gases are filtered of the dust they hold suspended. We fear some difficulty may be experienced in getting the gases to pass against the action of gravity.

At the present time few things are attracting more attention than the use of anthracite in the manufacture of iron. In America for a long time this fuel has been employed, but not, as it appears, with anything like the economy which has been recently obtained by Mr. Samuel Blackwell, of the Yniscedwin iron works, in South Wales. For some weeks past the results upon a new blast furnace, constructed after many experiments, have been the production of 1 ton of pig iron with 18 cwt. of coal in the furnace. This is, we believe, the greatest economy which has as yet been effected in the make of iron, and this anthracite iron is said to possess properties which render it peculiarly valuable for steel making.

Messrs. Vivian and Sons, of the Llandor smelting and alkali works, Swansea, appear to have been eminently successful in their application of the new furnaces-Gerstenhofer's patent-for the combustion of the sulphur, sublimed from the copper ores, and the conversion of it into sulphuric acid.

If this process is adopted at all the smelting works, Swansea will be relieved from the cloud of copper smoke which is ever hanging over it, and many thousands a-year will be saved by the conversion of the sulphur now wasted into an article which is in extensive use in manufactures.

VIII. PHYSICS.

LIGHT.-Professor Roscoe, of Owens College, writes us that in the last number of our Journal, in an article on De la Rue and Celestial Photography, the author has unwittingly done him an injustice in attributing to him the claiming of a discovery which was already known. Referring to the statement as to the well-known difference between the intensity of light from the centre and from the border of the sun's disc, Dr. Roscoe writes, "What I believe to be original in my communication, is the numerical determination of the amount of a difference which has been long observed."

Dr. Memorsky and Professor Brucke, in a paper communicated to the Vienna Academy, describe diffuse daylight as strongly reddish, just as gas or lamplight is yellow. The only perfectly white light, they tell us, is the electric light from charcoal points. The light of burning magnesium, and the combustion of phosphorus in oxygen, they say are violet.

M. A. Bertin has examined the constitution of glacier ice by polarized light. He has found that the superficial part of the higher glaciers is composed of agglomerated snow; but lower down, where the water has sunk into the fissures and become frozen, crystallization and true ice are found.

Professor Bunsen has made a discovery in connection with the absorption-spectrum of Didymium which may prove of great theoretical importance. In a paper which he published in conjunction with Professor Bahr some time ago, it was shown that slight differences were observed in the absorption-spectrum of sulphate of didymium according as the light was allowed to pass through a crystal or through a solution of the salt. Since that time Professor Bunsen has found that the erbum and didymium spectrum undergo alteration if polarized light be employed and either the ordinary or the extraordinary ray be allowed to pass through the crystal. It has also been found that whilst, when spectroscopes with one prism and with a telescope of moderate power are employed, the spectrum of the various didymium compounds do not show any difference, yet most undoubted differences are noticed when more powerful instruments are used. These differences cannot, in our present complete state of ignorance of any general theory for the absorption of light in absorptive media, be connected with other phenomena. They remind one of the slight and gradual alterations in pitch which the notes from a vibrating elastic rod undergo when the rod is weighted, or of the change of tone which an organ-pipe exhibits when the tube is lengthened. These curious phenomena form the subject of a long paper by

Professor Bunsen, which appears in the September number of the Philosophical Magazine.'

HEAT. According to some experiments made by M. Gripon on the conducting power of Mercury for heat, it appears that if the conducting power of silver 100 that of mercury = 3.54. It stands therefore the last of the metals, and a little before marble or gas coke. The author mentions that in this case the conducting power for heat and for electricity is very different, the former being 3 54, and the latter 1.80.

Although scarcely coming under the heading of " Heat," yet as they point to a possible means of storing up heat and force for future use, we give here an abstract of Professor Graham's most remarkable discovery in dialysis. The Professor finds that atmospheric air drawn through films of caoutchouc leaves behind a large portion of its nitrogen. The septum has no porosity, and is really impervious to air as gas; but the india-rubber film is capable of liquifying the individual gases of which the air is composed, whilst the oxygen and nitrogen, in the liquid form, penetrate the substance of the membrane unequally, and appear on the other side, where they again become gaseous. The rubber film thus becomes a dialytic sieve for atmospheric air, and allows very constantly 41 6 per cent. of oxygen to pass through instead of the 21 per cent. usually present in air. This dialysed air rekindles wood burning without flame, and in many other respects can replace pure oxygen for laboratory and technical purposes.

ELECTRICITY.-The electro-chemical properties of Magnesium have been applied to a very useful purpose by M. Roussin. Hitherto, in the toxicological examinations for metals, zinc has been exclusively employed, but this metal, as met with in commerce, is always impure, and the employment of magnesium has now been proposed as a substitute. Magnesium has the double advantage of rapidly and completely precipitating poisonous metals, without the danger of introducing any other poisonous substance. Arsenic and antimony are not precipitated, but will be found in the gas disengaged and in the liquid remaining. The author destroys organic matter by the usual methods, concentrates the acid liquor, and then introduces ribbons of magnesium as long as any deposit is formed. This precipitate is washed and examined by the usual method for metals. If the operation be conducted in a Marsh's apparatus, the gases may at the same time be examined for arsenic and antimony. The magnesium now to be purchased, in the form of ribbon or wire, is almost perfectly pure, and its price is so moderate that this can be no hindrance to its general use in laboratories.

Some new electric batteries have been described by M. Mouthier.

In the first he uses sulphuric acid and iron. In a cylindrical vessel of iron he places a prism of carbon, and then pours in dilute sulphuric acid. The carbon and iron form the two poles. Two of such batteries are sufficient to cause the ordinary telegraphic bell to ring. The batteries are said to be cheap, inasmuch as the sulphate of iron produced may be used in another system, composed as follows:-In a cylindrical vessel containing a concentrated solution of protosulphate of iron, the author places a cylinder of zinc and a prism of carbon forming the two electrodes of the pile. The zinc dissolves, hydrogen is disengaged, and hydrated sesquioxide of iron precipitated. Two elements of this kind served for an electric. bell for several months.

M. Zaliwski-Mikorski has announced to the French Academy that he finds smearing the zines of a Bunsen's battery with grease will answer the same purpose as amalgamating them. The fact may be as he states, but certainly he is not very happy in his explanation when he says that the grease acts as a body rich in hydrogen; that is to say, as a combustible body.

IX. ZOOLOGY AND ANIMAL PHYSIOLOGY.

A REPORT of the Proceedings of the British Association at Nottingham in reference to the subjects of our Chronicle will be found elsewhere. The most remarkable feature in the Meeting in this regard was the advocacy of Darwinism by the President, Mr. Grove, -as part of the Law of Continuity then enunciated by him-and the general support which the theory of the Origin of Species by modification and descent received from the leading men of Section D.

We understand that it is proposed to hold an Anthropological Congress in Calcutta on a very extensive scale. The Government is intending to inaugurate an Exhibition of Arts and Manufactures in that city in 1869 and the members of the Royal Asiatic Society conceive that this will be a suitable and valuable opportunity for an exhibition of living men of various races. Calcutta is itself a city peculiarly fitted for such a gathering: in addition to the great variety of the tribes of the continent, individuals of whom are abundant within its walls, Chinese, Malays, Andamanese, Singalese, Polynesians, and Australians are to be found amongst the shipping, and no doubt a large number will be attracted by the exhibition. The Council of the Asiatic Society have accordingly addressed the Indian Government for assistance in carrying out their scheme, with a partial success, and there is every reason to believe that such an exhibition of men as was never before witnessed will be visible in