arranged in a most unscientific manner, and containing opaque objects between the speculums. "Whatever they are," says he, when speaking of the objects," the upright figures between the speculums should be slender, and not too many in number, otherwise they will too much obstruct the reflected rays from coming to the eye." This shews in a most decisive manner, that Harris knew nothing of the kaleidoscope, and that he has not even improved the common catoptric cistula, which had been known long before. The principle of inversion, and the positions of symmetry, were entirely unknown to him. In the 6th scholium, he speaks of rooms lined with looking-glasses, and of luminous amphitheatres, which, as the Editor of the Literary Journal observes, have been described and figured by all the old writers on optics.*

The persons who have pretended to compare Dr. Brewster's kaleidoscope with the combinations of plain mirrors described by preceding authors, have not only been utterly unacquainted with the principles of optics, but have not been at the trouble either of understanding the principles on which the patent kaleidoscope is constructed, or of examining the construction of the instrument itself. Because it contains two plain mirrors, they infer that it must be the same as every other instrument that contains two plain mirrors, and hence the same persons would, by a similar process of reasoning, have concluded that a telescope is a microscope, or that a pair of spectacles, with a double lens is the same as a telescope or a microscope, because all these instruments contain two lenses. An astrononomical telescope differs from a compound microscope only in having the lenses placed at different distances. The progress of the rays is exactly the same in both these instruments, and the effect in both is produced by the enlargement of the angle subtended by the object. Yet surely there is no person so

* The reader is requested to examine carefully the propositions in Harris' Optics, which he will find reprinted in the Literary Journal, No. 10. He will then be convinced, that Harris placed both the eye and the object between the mirrors, an arrangement which was known 100 years before his time.

senseless as to deny that he who first combined two lenses in such a manner as to discover the mountains of the moon, the satellites of Jupiter and Saturn, and all the wonders of the system of the universe, was the author of an original invention. He who produces effects which were never produced before, even by means which have been long known, is unquestionably an original inventor; and upon this principle alone can the telescope be considered as an invention different from the microscope. In the case of the kaleidoscope, the originality of the invention is far more striking. Every person admits that effects are produced by Dr. Brewster's instrument, of which no conception could have been previously formed.

All those who saw it, acknowledged that they had never seen any thing resembling it before; and those very persons who had been possessors of Bradley's instrument, who had read Harris's Optics, and who had used other combinations of plain mirrors, never supposed for a moment, that the pleasure which they derived from the kaleidoscope had any relation to the effects described by these authors.

No proof of the originality of the kaleidoscope could be stronger than the sensation which it created in London and Paris. In the memory of man, no invention, and no work, whether addressed to the imagination or to the understanding, ever produced such an effect. A universal mania for the instrument seized all classes, from the lowest to the highest, from the most ignorant to the most learned, and every person not only felt, but expressed the feeling, that a new pleasure had been added to their existence.

If such an instrument had ever been known before, a similar sensation must have been excited, and it would not have been left to the ingenuity of the half learned and the half honest to search for the skeleton of the invention among the rubbish of the 16th and 17th centuries.

The individuals who have been most eager in this search, did not, perhaps, calculate the degree of mischief which they have done to those who have been led, upon their authority, to en croach upon the rights of others, and thus subject themselves to

very serions consequences. The delay which has taken place in commencing legal proceedings, has not arisen from any doubt of the complete originality of the kaleidoscope, and of the defensibility of the patent. As soon as the patentee has made himself acquainted with the circumstance of the individuals who have invaded his patent, with the channels through which they have exported their instruments, and with the amount of the damage which they have done, he will seek for that redress which the law never fails to afford in cases of notorious and unprovoked piracy. We are well assured, that it never was the intention or the wish of Dr. Brewster to interfere with the operations of those poor individuals who have gained a livelihood from the manufacture of kaleidoscopes. We know that it will always be a source, of no inconsiderable gratification to him, that he has given employment to thousands of persons, whom the pressure of the times had driven into indigence; and even if a decision in favour of his patent were given, he would never think of enforcing it, excepting against that class of opulent pirates who had been actuated by no other motive but the exorbitant love of gain, in wantonly encroaching upon the property of another.

An

The patent kaleidoscopes are now made in London, under Dr. Brewster's sanction, by Messrs. P. and. G. Dollond, W. and S. Jones, Mr. R. B. Bate, Messrs. Thomas Harris and Son, Mr. Bancks, Mr. Berge, Mr. Thomas Jones, Mr. Blunt, Mr. Schmalcalder, Messrs. Watkins and Hill, and Mr. Smith. account of the different forms in which these ingenious opticians have fitted up the kaleidoscope, and of the new contrivances by which they have given it additional value, will be given in Dr. Brewster's Treatise on the Kaleidoscope, now in the press. The public will see, from the examination of these instruments, how much they have been imposed upon by spurious imitations, sold at the most exorbitant prices, and made by individuals entirely ignorant, not only of the principles and construction of the instrument, but of the method of using it.

ART. XVIII. An Account of the New Alkali lately discovered in Sweden.

THE

HE discovery made by M. Arfwedson of a new alkali, and announced in the last Number of the Journal, has been abundantly confirmed by the researches of other chemists. Its importance has drawn the attention of the whole chemical world, and much new information relative to its nature and its sources, has since been added, which we shall endeavour to comprise in the following account of this body.

Lithia (the name given to the new alkali) was first found in the petulite, a mineral from the mine of Utoen in Sweden. It may be obtained very readily by fusing the mineral with potash, dissolving the whole in muriatic acid, evaporating to dryness, and digesting in alcohol: the muriate of lithia being very soluble in that fluid, is taken up, whilst the other salts remain, and by a second evaporation and solution, is obtained perfectly pure.

The muriate is itself a very characteristic salt of the alkali. It may easily be decomposed by carbonate of silver, and the carbonate treated with lime yields pure lithia.

The exact quantity of lithia in the petalite is doubtful, but it cannot contain much more than five per cent. A more abundant source has however been found in the Triphane or Spodumene, which according to M. Arfwedson, who also first pointed out in it the existence of lithia, contains eight per cent. of the new alkali. The same chemist has likewise ascertained its existence in another mineral from Utoen which is called crystallised lepidolite in the proportion of four per cent.

The pure alkali is very soluble in water, has a very acrid caustic taste, like the other fixed alkalies, and acts powerfully on blue vegetable colours. When heated on platinum, it acts on it. It has a strong affinity for acids, and a very high neu. tralising power, even surpassing that of magnesia. Its solution precipitates the earthy and metallic salts, nearly as solutions of the other alkalies do.

Placed in the Voltaic circuit, Sir H. Davy shewed that it

was decomposed with the same phenomena as the other alkalies. A portion of its carbonate being fused in a platinum capsule, the platinum was rendered positive and a negative wire brought to the upper surface. The alkali decomposed with bright scintillations, and the reduced metal being separated, afterwards burnt. The small particles which remained a few moments before they were reconverted into alkali, and allowed a short examination, were of a white colour, and very similar to sodium. A globule of quicksilver made negative, and brought into contact with the alkaline salt, soon became an amalgam of lithium, and had gained the power of acting on water, and evolving hydrogen, an alkaline solution resulting.

The chloride of lithium obtained by evaporating the muriate to dryness, and fusing it, is a white semi-transparent body, analagous in its appearance to the chlorides of potash and soda, but very different from them in its general properties. It is extremely deliquescent, whereas they are not so in this respect it almost equals muriate of lime. Its solution crystallises with great difficulty, but by evaporation affords minute needle-form crystals. It is very soluble in alcohol, but the chlorides of potash and soda very little so. Its solution, or the moist salt, has the property of tinging the flame of alcohol of a fine red, somewhat like strontian, but the other alkaline muriates have not this power. It fuses below a red heat, and when heated powerfully in the open air, it gradually loses chlorine, absorbs oxygen, and becomes strongly alkaline.

some cases a singular

The nitrate is a very

All its salts are very fusible, but in degree of insolubility belongs to them. soluble salt, deliquescent, and capable of crystallising in rhomboids. It has a very aigre taste: heated it readily fuses, and is then decomposed with the same phenomena as nitre.

The sulphate of lithia is a salt which crystallises readily in small rectangular prisms; they are perfectly white, and possess much lustre; have a saline taste, very different to potash or soda; are more soluble in water than sulphate of potash;