most satisfactorily demonstrated, as well as the portability of the light itself. The amount of heat given off by M. Jablochkoff's candle is comparatively small, the glass globe of one of the lanterns used for lighting up the ship having been found to be only just comfortably warm after having been lighted for twenty minutes. The last experiment tried was, scientifically speaking, the most interesting of the whole, demonstrating as it did that M. Jablochkoff has succeeded in entirely doing away with the necessity for using carbons for the electric light. His newest form of candle consists of a thin plate of his kaolin composition, about 1 inches long by 1 inch broad, and aboutth inch thick. The sides of the plate are inserted in grooves cut in the wires forming the electrodes of the battery, which project very slightly above the top of the plate. In order to light this new form of candle a bridge of ordinary graphite is carried along the top edge of the porcelain plate. The graphite become incandescent, causing the porcelain to melt, which then becomes a conductor. The graphite gradually disappears, and the melted portion of the porcelain becomes incandescent, gradually vapourising at the rate of a millimetre an hour. The light given out by the porcelain seems softer, mellower, and much more constant and steady, than that given off by the combination of carbon and porcelain : indeed, after five minutes' examination with black spectacles, we failed to discern anything more than a barely perceptible start at distant intervals.

A singular case of the production of heat has been communicated to the French Academy of Sciences by M. J. Olivier. A square rod of steel, So centimetres in length and 15 millimetres square, is grasped firmly by both the hands of the operator, one of the hands being placed in the middle of the rod, and the other at one end. The free extremity is strongly pressed against an emery wheel revolving very rapidly. After a few minutes the extremity thus rubbed becomes strongly heated: the hand placed in the middle of the bar does not experience any feeling of heat, but the one at the ether extremity is heated to such an extent that the operator is compelled to let go.

The official appreciation of scientific knowledge in our Colonies is admirably shown by the official reports recently issued by Colonel A. Brunel, the Commissioner of Inland Revenue for Canada. These are reports on weights and measures, and on the analysis of gas and food. A sure evidence of the continued material progress of a country is shown by its appreciation of scientific knowledge as applied to accurate measurement. For the maintenance in Canada of the British standards of length and weight, and for the issue to the local authorities, as well as to chemists and physicists there, of precise copies of these standards, there has been established at Ottawa a department under proper scientific direction, and provided with apparatus of the highest class. This department has also the appointment and control of the Inspectors whose duty it is to inspect the trade weights and measures. These numerous Inspectors are provided with weighing and measuring apparatus of the best design. From Colonel Brunel's report it appears that"The analysis of gas and food is being carried out in the Dominion in accordance with the latest scientific experience. In Canada, as elsewhere, condiments, coffee, and milk appear to be largely and unwholesomely adulterated. Quinine wine, which is an article of great demand in Canada, is found as sold to be a highly alcoholised wine containing gentian and nux vomica, with 20 per cent of alcohol, and is therefore a powerful stimulant instead of being a simple tonic. The testing of gas supplied for lighting and heating purposes is also the duty of the Department at Ottawa, and for this purpose chemists have been appointed, and a large quantity of photometric apparatus obtained from Mr. Sugg, of Westminster. The law appears, however, scarcely to have come yet into active operation, and we regret to see that it is at present deficient in relation to the inspection of the illuminating power of gas. We are glad to find that Colonel Brunel has been so well supported in the difficult task he has initiated, and we trust that his Department may be imitated in other of our Colonies and Dependencies.

MICROSCOPY.-The " Monthly Microscopical Journal" of May contains a valuable paper by Mr. Thomas Palmer, B.Sc., "On the Various Changes Caused in the Spectrum by Different Vegetable Colouring Matters." The paper is accompanied with several spectrum charts, and contains a detailed account of the processes used in preparing the various colouring matters for examination, and also accurate measurements, reduced to wave lengths, of the positions of the various absorption bands. Mr. Sorby, in his remarks on the paper, stated that vegetable colouring matters are much more complex than is generally supposed; most of them are undoubted mixtures of two or three kinds of matters, and even the chlorophyll, the green colouring matter alone, is composed generally of two green matters, which exist separately in certain plants. The line it would be most important to carry out would be, what were the chemical differences which gave rise to these changes in the spectra.

"Notes on Inclusions in Gems, &c.," by Isaac Lea, LL.D. This paper, published in the "Proceedings of the Academy of Natural Sciences, Philadelphia," and reprinted in the "Monthly Microscopical Journal," vol. xvii., p. 198, may be consulted with advantage by all persons interested in this subject. It contains the history of the cavities in crystals and their contents, from the paper by Sir Humphry Davy, published in the Philosophical Transactions," 1822, to the present time; a full list of references is given, and it forms a valuable contribution to the bibliography of this interesting subject.

An ingenious modification of the achromatic condenser has recently been constructed by Messrs. Beck. It consists of an achromatic combination mounted in the usual fittings; over this slides a cylinder upon an eccentric rotating axis; the disk closing the upper end contains a series of holes, which can be brought accurately one by one over the lenses of the condenser by the rotation of the fitting; these apertures carry a series of lenses, by which a modification of the illuminating pencil is obtained. Lenses, achromatic or not, may be used to alter the aperture and focal length; spot lenses, central or marginal stops can all be employed with the greatest facility, rendering the variety of illumination attainable almost infinite.

Into

A new and simple oblique illuminator has been contrived by the Rev. Lord S. G. Osborne, M.A., which he calls the "Exhibitor." The foundation consists of a "Darker" stage, as used for carrying selenite plates in polarising. Two counter sinkings are turned in the revolving ring, the_top one rather larger in circumference and shallower than the lower one. the lower sinking is dropped a disk of blackened metal, with a small hemispherical lens mounted in the centre. Into the upper sinking are placed thin metal disks with certain apertures made in them; the front of these disks is just level with the face of the stage, the back close to the front of the disk holding the small lens. A fine screw is cut into the back part of the revolving ring, coming up just below the lower counter sinking; into this screws a brass ring carrying another hemispherical lens of the full size of the aperture. The screw movement has a milled edge, permitting the distance between the lenses to be regulated. The apertures may be made as found useful; one very successful consists of No. 1, a fine slit, in length about the aperture of the upper lens in the centre; No. 2, a similar aperture a little way, say not quite its own length from the centre; Nos. 3 and 4, a pin hole and a triangle, also a little out of the centre; these may all be cut in one disk. On the stage there are two steel springs for holding the sides, giving the means of shifting them in any direction. Abraham's achromatic prism is to be preferred to the mirror, and the flame of the lamp turned edgeways.

I. The Chemistry of the Future.

II. On the Probable Origin and Age of the Sun. . III. The Glacial Period in the Southern Hemisphere. Recent Advances in Telegraphy.

IV.

V. On the Present Condition of Chile.

NOTICES OF SCIENTIFIC WORKS.

Carpenter's" Mesmerism, Spiritualism, &c., Historically and Scientifically Considered."

Thomé's "Text-Book of Structural and Physiological Botany."
Woodward's "The Geology of England and Wales."

Goodeve and Shelley's "The Whitworth Measuring-Machine, including Descriptions of the Surface-Plates, Gauges, and other Measuring-Instruments, made by Sir Joseph Whitworth."

Lord Rayleigh's "Theory of Sound."

Everett's "Elementary Text-Book of Physics."

Lardner's "Handbook of Natural Philosophy.-Heat."

Thearle's "Theoretical Naval Architecture: a Treatise on the Calculations involved in Naval Design."

Angell's" Elements of Magnetism and Electricity."

Gordon's "The Winds, and their Story of the World. Vis Inertia in the Ocean."

Battye's "What is Vital Force? or a Short and Comprehensive Sketch, including Vital Physics, Animal Morphology, and Epidemics." Temple's "Aids to Chemistry, specially designed for Students preparing for Examinations."

Taylor's "The Aquarium, its Inhabitants, Structure, and Management."

(Including the Proceedings of Learned Societies at Home and Abroad, and Notices of Recent Scientific Literature).