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accomplishment of the object under consideration, we will endeayour to make plain.

We will suppose the lower piece of charcoal, in an upright electric lamp, to be fixed at one end of a balance-lever or beam, to the other end of which is attached a piece of iron somewhat heavier than the charcoal, this piece of iron being placed within a coil formed by a portion of the conducting wire of the battery. The weight of the iron will in this case determine the preponderance of the balance-beam in its favour, when no current is passing, and will thus cause the two charcoal points, their position being so arranged beforehand, to be in contact with each other. If the circuit be now completed, the electric current will flow through the charcoal points, and the spark of light will appear, but at the same instant the current flowing through the coil will draw the piece of iron upwards, and the charcoal points will consequently be drawn apart, the electricity, in the form of the arc of light before referred to, continuing to flow between them. If the adjustments be made with delicacy, the distance to which the iron will be attracted upwards will be exactly equal to that to which the charcoal points should be drawn asunder; and should an accidental circumstance (such as the fracture of the charcoal points in consequence of the heat) occur to break the circuit, the iron will immediately fall and push the points into contact again, when the action will go on as before. It is by a combination of mechanism on this principle with clock-work, too complicated to describe, that most of the so-called electric lamps are constructed.

blowpipe, that is, by the introduction of a jet of oxygen into
the flame of pure hydrogen. Submitted to this heat, the hardes:
metals not only melt like wax, but are boiled and converted
into vapour. Even the diamond itself cannot remain in
presence, but is burnt up and transformed into gaseous matte.
There are, however, some substances, which, with the greates
heat at present attainable, will not burn, and one of thess
is lime. The action of the oxyhydrogen blowpipe on lime,
therefore, can only render it incandescent, or white hot, but so
intensely and luminously hot that no eye can gaze on it for a
moment without injury. Neither the discovery nor the use of this
light are modern. It has been successfully used for illuminating
dissolving views, both at the London Polytechnic Institution and
elsewhere, for very many years. It was first used in 1826 bạ
Lieutenant Drummond, who then had the conduct of the Ord-
nance Survey of Scotland and Ireland, and who employed it for
signals in connexion with that survey. By collecting its rays in
the focus of a paraboloid he was able to render it visible all the
way across St. George's Channel, from a point near Holyhead
into Ireland, a distance of sixty-four miles, and subsequently, in
Scotland, from the summit of Ben Lomond to that of Knock
Layd, a distance of ninety-five miles. It speedily became known
as the Drummond Light, but no practical use had ever been
made of it, except as already intimated, until the establishment
recently of a company called the "Lime Light Company," who
a short time since drew considerable attention to it, by lighting
with it the finished half of the new bridge at Westminster.

The principal obstacle to the use of the lime light, until the com mencement of the operations of this company, was the tendency of the lime to crack and fall to pieces, under the intense heat to which it was subjected. This the company propose to obviate by the employment of a patented metal sheath to contain the lime, together with a clock-work movement, which has the effect of gradually bringing fresh surfaces of lime into contact with the jets.

The advantages claimed for the lime light, besides its brilliancy, are, that it is superior to every other artificial light in quality, and that it is less deleterious than any other light, and far more economical. Its brilliancy is beyond question; and there can bə no doubt that, in quality, it is superior to any other artificial light,

With regard to the second of the desiderata mentioned, viz:, the equalization of the power of the battery furnishing the electric current, this also has been accomplished in a wonderful manner. We have seen that magnetism can be communicated to a bar of soft iron by a current of electricity passing round it: Professor Ersted, of Copenhagen, has discovered a remarkable circumstance the reverse of this, viz., that a current of electricity can be produced from permanent magnets. By the communication of motion to a wheel upon which a number of such magnets are arranged, a current of electricity, proportionate in power to the number and size of the magnets, may be obtained. This current, to distinguish it from the voltaic current, is called the magneto-electric current. It is of precisely the same character as the voltaic current, so far, at least, as has been at present ascertained,-but-excepting only the electric light,-as it rivals even the sun in has the advantage of continuing always uniform in intensity, however long the battery supplying it may be in action. Notwithstanding the power and brilliancy of the electric light, which is identical in quality and chemical action with sunlight, its cost, together with its lack of portability, renders it scarcely probable that it can come, at least in our day, into general use. There are, however, many purposes to which it may be applied with manifest advantage. It is especially suitable for employment in lighthouses. Professor Faraday, in a recent lec-pure hydrogen be used, there will be no production of carbonie ture at the Royal Institution, mentioned that it had been in use for the previous six months at the North Foreland, and had shown thence into France, and that never once during the whole of that period had it failed in doing its duty.

Professor Wray's light, which was exhibited at Oxford on the occasion of the recent meeting of the British Association for the Advancement of Science, and has since been exhibited at Cowes, and elsewhere, is another form of the electric light. Instead, however, of proceeding from a stream of electric sparks bridging the interval between two carbon points, it is emitted by a very fine stream of mercury, heated to an almost inconceivable degree. Each of what we have spoken of above as the cut ends of the conducting wire of the battery is dipped into a separate cup of mercury, the one cup being placed immediately below the other, but the two cups communicating by means of a glass tube, of very fine bore, one end of which passes through the bottom of the upper cup, while the other end dips into the mercury in the lower one. By this arrangement, the electric current is made to pass through the fine stream of mercury which is constantly passing from the upper cup to the lower one, through the glass tube, and this stream of mercury,-which ought to be finer than the point of à lady's needle,-is thereby heated so intensely as to cause it to give off a pale pure light at least equal in power to that which would be obtained by the same current being made to pass between carbon points. This light continues perfectly uniform so long as the battery continues in action and there is mercury in the upper cup; but it has the disadvantage of giving a most ghastly hue to the human countenance. On the other hand, it brings out certain colours,-mauve, for one,-with an extraordinary brilliancy, such as they do not exhibit when illumined by any other known light. We now come to the consideration of the equally powerful and beautiful light known by the name of the "Lime Light." This light, like Professor Wray's light, is not the effect of combustion but of ignition, or that state of incandescence which is produced by intense heat. Except the heat produced by the arc of the electric current, the most intense heat that can be artificially produced, greater than that of the most powerful blast furnace, is the heat obtained by the use of the oxyhydrogen |

the purity and power of its rays. Green and blue shades of colour can be recognised and compared under its influence as accurately as by daylight. Plants and flowers present, when illumined by it, all the brilliancy and delicacy of tint with which they charm the eye when seen by day. It exhibits, in fact, all objects in their natural colours.

With reference to its asserted advantage as being less deleterious than other modes of illumination, we may observe that if

acid vapour, which is given off in abundance by all lights depen dant on combustion. Moreover, as the oxygen required for the lime light must be supplied in its separate state, the lime light will not, like the lights produced by combustion, abstract oxygen from the atmosphere in which the light is used, thus causing those who breathe that atmosphere to inhale an undue proportion of nitrogen. As both carbonic acid and nitrogen are deadly poisons, the lime light has certainly, from a sanitary point of view, advantages over such lights as are obtained by burning gas, oil, candles, etc. There is, however, one point to which we must refer, with regard to the use of the lime light in private dwellings, it being urged in its favour that it will not injure the most costly decorations or embellishments, viz., the possible diffusion of the sublimed lime. Although the lime will not burn in the intense heat to which it is subjected, it will, nevertheless, sublime, or gradually diffuse itself in an almost impalpable powder. Now this powder is still lime, and lime is caustic; and as caustic, or "quick" lime, will "slack" when exposed to the watery vapour in the atmosphere, in such fine particles, we should be somewhat distrustful of its effect upon a gallery of fine pictures, or upon valuable upholstery, until it had been ascertained, by a somewhat lengthened experience, that the sublimed lime was confined to the case or lamp in which the light was used.

We now come to the question of economy, which is one involving a variety of considerations. To commence with, it may be observed that, as the lime light requires the use of two separate gases, which must not be mixed, except at the jet of each separate light, two lines of mains are necessary for their conveyance for street lighting; although it must be admitted, per contra, that as the quantity of these gases required to ignite the lime is far smaller than the quantity of coal gas requisite to produce the same volume of light by combustion, the weight of metal in both mains would probably be less than that in a single ordinary gas main. Next comes the cost of the gases themselves. First, the pure hydrogen. This is much more expensive than ordinary car. buretted hydrogen, or coal gas. The latter, however, can be used for the lime light, and in fact was so used for the lights on Westminster Bridge, but its use not only detracts from the sanitary advantage we before mentioned, since it causes the production

SEPT. 1860.]

LITERATURE, THE SCIENCES, AND THE ARTS.

As

35

gaze on it without inconvenience to the eye. Another was moved
about from place to place beneath the portico, and its light thrown,
by a reflector, at one time on the statue of Nelson, which it
brought out from the dark background of the sky like a white
spectre; at another, on the statue of King George, whose shadow
was thrown as darkly and well-defined upon the façade of Morley's
Hotel as though it had been painted upon it in dense black. But
few particulars have transpired respecting its nature or principle;
but, so far as we can judge, it most probably consists of some
method of judiciously supplying oils or other hydro-carbons with
a supporter of combustion, such as oxygen, for which they have a
strong affinity. It may yet possibly be capable of achieving a
position in consequence of its portability, which, cæteris paribus,
gives it an advantage over both the electric light and the lime
light.

of carbonic acid, but it also involves the expenditure of a much
larger quantity of oxygen than would otherwise be needed. Now
as oxygon is by far the dearest element used in the production
of the light, the saving of the oxygen thus wasted would pro-
bably more than counterbalance the difference between the price
of pure and that of carburetted hydrogen. We may, therefore,
for the purpose of the present discussion, assume that the one is
as cheap as the other. The chief point on which the question
of expense therefore depends, is the cost of the oxygen. The
small quantities in which that gas has hitherto been required
have generally been prepared from the black oxide of manganese,
or, more costly still, from chlorate of potash, which, by the way, is
a substance very suggestive as regards the effect of demand on
supply, for within our own memory it has been a guinea an
ounce, while it is now procurable at little more than a shilling per
pound. The process, however, by which the Lime Light Com-
pany are at present obtaining their oxygen, is one founded on
the principle of a patent by Michele (taken out in 1853), who
takes advantage of the fact that protoxide of barium, at a low
red heat, will absorb an additional quantity of oxygen from
the atmosphere, and will liberate such extra quantity on being
raised to a cherry-red heat; Michele's process consisting of an
ingenious alternation of the two degrees of heat acting on the
material in a closed chamber, admitting air to be decomposed, and
its oxygen absorbed, when at the lower temperature, and liberating
and collecting this absorbed oxygen when at the higher one.
there is scarcely any loss of material in this process, the cost of the
oxygen reduces itself to that of the fuel and the labour, so that this
would certainly appear to be a more promising method of obtain-
ing oxygen than any previously adopted. There can be little
doubt that a demand for cheap oxygen, which would be the neces
sary result of any considerable use of the lime light, would set
many inquiring minds at work upon the problem; and as oxygen
is one of the most abundant elements with which the chemist is
acquainted, forming one-fifth of the bulk of atmospheric air, and
nearly 89 parts out of 100 by weight of water, it is highly pro-
bable that it will obey that law of the action of demand in the pro-lished in the Medical Times and Gazette of the 11th ultimo.
duction of supply which we have already illustrated. We are not
aware whether sufficient statistics of cost, of a reliable character,
have yet been obtained, to enable an authoritative statement to be
made as to the cost of oxygen in large quantities; but if, as has
been represented, it can be produced as low as eight, or even ten
shillings per 1,000 cubic feet, the lime light can scarcely fail to
be an economical one for many purposes. Like the electric light,
it is admirably adapted for application to lighthouses, and it
would also be a most desirable light for large open spaces, such as
London. If the company could put sufficient pres-
Trafalgar-square,
sure on their gases to force them to the top of the Nelson column
there, and could get permission to erect on the top of that column
an enormous lamp globe, in place of the unseen statue, they
would confer a great benefit, by converting that which is neither
useful nor ornamental as a monument, into the most magnificent
pillar lamp in the world.

THE DEATH-WOUND OF CHARLES XII.
his death. He was killed, the reader will remember, at the siege
A CONTROVERSY has long prevailed amongst the Swedes as to the
mode in which their illustrious monarch, Charles XII, came by
of Frederickshall, in Norway, in 1718. The question that has been
raised is, was he fairly killed at the hands of the enemy, or did
he die by treachery on his own side?

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About a year ago, the Swedish Government became anxious to have this question set at rest, by a careful examination of the the August of last year, in the presence of the reigning king, remains of the deceased monarch. Accordingly, on the 26th of Charles XV., of the great officers of state, and of a few of the leading physicians and surgeons of Stockholm, the royal sarcowas the seat of the fatal injury, very carefully examined. The phagus and coffin were opened, and the state of the head, which results of this examination, and of a very long discussion which Swedish Society of Physicians, appeared in their journal, Hygeia, took place on the reading of the report of the examination to the in March last, and an abridgement of the account given in that journal, from the pen of Dr. W. D. Moore, of Dublin, was pub

From this we learn that an examination of the corpse was made in the year 1746, and that the official account of this examination is extant. It was made, however, so imperfectly as to throw no light at all on the matter at issue.

When the coffin was reopened last year, the general appearances of the corpse quite corresponded with the description of those who saw it in 1746. A white linen cushion, filled with spices, lay over, contact with the face. Long white bags filled in the same way, and another under, the head,-a handkerchief, however, being in lay along the sides and arms. The hands, slightly drawn towards of coarse Silesian linen, the shroud of brown-holland. In the each other, were covered with white kid gloves. The shirt was shroud, on the left side, near the feet, was a little blue silk embroidered bag, tied up with blue silk, and containing a small seems little doubt was a piece removed from the king's left foot portion of one of the metatarsal bones of the foot, which there in 1709, after the wound he received at the disastrous battle of Pultowa, in which he and his forces were so completely beaten by Peter the Greatteri elli 3.

In place of a cap, the head of the royal corpse was encircled with a withered wreath of laurel! The top of the head was bald, but the back and sides were covered with thin light brown hair, The upper-lip was somewhat retracted; the eyelids interspersed with grey, and about an inch and a half long. The face was of course shrunken, but still showed the aquiline form of the nose. slightly open; the skin parchment-like, and of a greyish-yellow, or, in places, greyish-brown. The expression worn by the features was very calm and solemn.

It has recently been discovered that a light, scarcely surpassed
in power or brilliancy by either the electric light or the lime light,
is produced by the combustion of the metal magnesium, the
metallic base of the earth magnesia. This metal is lighter even
than aluminium, is as white as silver, and does not rust. Accord
ing to a recent account in one of the scientific journals, "it may
be hammered, filed, and drawn out into threads; it ignites at the
temperature at which glass melts, and burns with a steady and
vivid flame, the ash resulting being pure magnesia; while it has
been found experimentally that a very fine magnesian thread
emits a light equal to that given by seventy-four stearine candles
of five to the pound. These peculiar properties have suggested
the possibility of using it for illuminating purposes. To effect
this, it is only necessary to devise some mechanical means of
spinning the metal into thread; when this is attained, we shall
have a light more simple and efficient than any yet used, whether
electric or lime. The illuminating power may be increased to
any extent by adding to the size of the wick, the only requisites
to light being the magnesian thread, a clockwork arrangement to
supply it continuously as used, and a spirit lamp. Costly as
magnesium is, more economical modes of producing it will doubt-orbit or eye-socket having been completely carried away. The
less be suggested by the demand for it. It seems also that the
magnesian light will be specially valuable in photography, since,
according to Bunsen, the sun has only thirty-four times its photo-
chemical power."

Another light which has recently attracted some attention is the "Fitz-Maurice Light," so called from its having been introduced by Captain Fitz-Maurice. Its chief advantage is stated to be its portability. It was exhibited in Hyde Park about a year ago, and also at Trafalgar-square, at which latter place we had the opportunity of observing it. It is a lightapparently equal in quality to the lime light. One, enclosed by a ground-glass globe, illuminated the roadway opposite the National Gallery so that one could see to pick up a pin on the further side, while it was so soft and subdued by the ground-glass as to permit the spectator to

The centre of the forehead was disfigured by a depression,
On each temple was a black velvet patch,
found afterwards to correspond with a fracture of that part of the
bone of the skull.
adhering by means of something spread on the wrong side of the
velvet. Beneath these were the holes in the skin through which
the fatal missile had passed. That in the left temple was the
larger of the two; so, also, the opening in the bone was of much
greater extent on that side than on the other, the margin of the left

bones around the openings were much comminuted, and lines of
fracture extended from them, both on to the forehead and into the
with the cavities of the nose and top of the throat, was broken into
base of the skull, while the base of the skull itself, corresponding
many fragments. Besides the rags and spices used in the process
of embalming, loose portions of bone, and also the dried waxy
On carefully noticing the extent and character of the injuries tr
remains of the once regal and active brain, were discovered within
the cranium, but no trace of shot or other missile was found.
the bones, the direction of their broken margins, and so forth,
the examiners were of opinion that the missile, which was evi-
dently from some kind of gun, had passed through the king's
head from left to right; that, although nothing could be decided
with regard to the exact nature of the missile, it was probably

a musket or a grape-shot,-less probably, though still possibly, a case shot, or fragment of a bursted bomb-shell; that it must have been fired from a distance, its velocity having been evidently partly spent before it struck the king; that its path, as indicated by the injuries to the skull, was probably from a point higher than the spot on which the king stood at the moment he was hit,although the appearances on which this conclusion was founded might have been occasioned by the king's head being inclined at the moment; that the wound must have been instantly fatal; and lastly, that there is no evidence that his majesty was struck by more than one missile.

In the discussion which ensued, some difference of opinion arose as to which side of the head the missile had entered at; but all agreed that Charles XII. did not fall by the hand of one of his own followers. The Swedish name is thus completely freed from the slur which had been cast upon it by the suspicion that this illustrious monarch had owed his death to foul play.

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THE most interesting account of the recent eclipse of the sun which has yet been published, is that given in the letter from Mr. Warren De la Rue which appears in the Times of August the 9th. Mr. De la Rue is one of the astronomers who went to Spain to observe the eclipse, Spain being the only part of Europe in which the eclipse was total.

By means of an instrument called a Photoheliograph, Mr. De la Rue succeeded in obtaining, at various stages of the eclipse, some valuable "sun-pictures" of the sun itself. This instrument was originally designed by Mr. De la Rue, at the suggestion of Sir John Herschell, for the Observatory at Kew. It consists of a pyramidal tube, fitted with two combinations of lenses, and with conveniences for the introduction and exposure of sensitive plates. The sensitive plates are introduced at the larger end of the tube, the object glass being at the smaller end. The primary image of the sun, formed by the object glass, is not quite half an inch in diameter; but before this image falls on the sensitive plate, at the larger end of the pyramidal tube, it is enlarged, by means of secondary lenses, to a diameter of nearly four inches. So rapid is the action of the direct solar rays, that, in taking photographs of the sun, it is requisite that they should not be allowed to fall on the sensitive plate for more than a very small fraction of a second of time; and this is managed, in the case of the photoheliograph, in a very ingenious way. In front of the sensitive plate is an opaque slide, in one part of which is a very narrow slit. This slide is held, with the slit out of the line of light, by a loup of thread, which being, at a given signal, set on fire, the "slide flashes instantly across the axis of the instrument, allowing the sun's rays to pass momentarily through the slit on to the sensitive plate," upon which the sun's image is thus fixed almost instantaneously.

*

Some were like luminous clouds; others were in the form of streaks, more or less curved; one was shaped like a kettle; another like a ship in full sail, and one, a very remarkable one, is described as shaped like a boomerang. The dimensions of some of these luminous projections are truly astounding, their breadth being often 28,000 miles, and their length varying from 42,000 to 56,000 miles. So far as observed by Mr. De la Rue, they were not at any one time arranged in the regular, continuous, "Bailey's Beads" fashion; but another observer describes them as at one moment presenting, on the south-western quarter of the moon's edge, the appearance of a long continuous row of golden prominences. It is curious that the boomerang protuberance, although photographed distinctly, was invisible to the eye. Tlás, Mr. De la Rue suggests, may be owing to its having possibly been of a faint purple tint. Mr. De la Rue expresses no opinion as to the nature or causes of these curious protuberances, or as to their relation to the sun or its atmosphere.

The general phenomena of the eclipse, as observed in Spain, were in harmony with what is recorded of the phenomena of former total eclipses. The indigo hue of the sky, lowering into orange at the horizon,-the dark blue of the mountains,-the deepshadows,-the bewilderment of birds and beasts,-the quietude of man, all combined to give to nature a deep solemnity of aspect. scarcely conceivable by those who have not themselves actually witnessed a total solar eclipse,-the obscuration caused by which is many times greater than that occasioned by the largest partial eclipse. There are but few persons who have witnessed a total solar eclipse, only two solar eclipses having been total at London since the Norman conquest. The first of these occurred in the

year 1140, the other in 1715. Eclipses of the sun, total in some parts of Europe, will occur on the 31st of December, 1861, in 1870, in 1887, and 1896; but the next solar eclipse total at London will not take place until some years after the commencement of the twentieth century.

THE COAL AND GUANO DYES.—MAUVE, MAGENTA, ETC. Ir is now nearly sixteen years since Mr. Murdoch astonished the people of Birmingham by illuminating the front of the great manufactory of Boulton and Watt, at Soho, with gas produced from coal. What had hitherto been an idle dream, became a recognised fact, and the practicability of lighting the streets of large towns by means of coal-gas was not long in being established. Since then the science of chemistry has made immense progress, and has found amongst the products of the distillation of coal substances of which the value had hitherto been unknown. Amongst these is the liquid from which aniline is prepared, and which in its turn yields the magnificent dye known as "mauve." Nor is the source of the dyes known as "fuschine" and "magenta" any less wonderful. They are obtained from "murexide," which is derived from uric acid, while the uric acid of commerce is derived from

guano.

When coal is submitted to distillation in large iron retorts, its complex bituminous constituents are resolved into bodies of more simple composition. These are gaseous, liquid, and solid.

The gaseous products are hydrogen, carbonic oxide, carburetted hydrogen, olefiant gas, sulphuretted hydrogen, carbonic acid, cyanogen, sulphoryanogen, sulphurous acid, hydrochloric acid, nitrogen, and vapour of bisulphide of carbon and water. Only the four first-mentioned gases are combustible; and therefore, in the manufacture of gas for illuminating purposes, all the others have to be removed. By passing the mixed gaseous products as they proceed from the retorts through milk of lime, all the nonilluminating gases and vapours are removed as completely as possible. Of the four illuminating gases, only the olefiant gas possesses any considerable luminous properties, so that the quality of the gas supplied for lighting purposes is always estimated by the percentage of olefiant gas which it contains.

Altogether, during the progress of the eclipse, Mr. De la Rue caused thirty-one photographs to be made. The time at which each was taken was accurately noted, a most valuable record for the verification of astronomical calculations being thus formed. So long as any portion of the sun's disc remained unhidden by the moon, the photographs were taken in the manner above indicated, but as the totality approached, and a longer exposure became necessary, the slide apparatus was no longer employed; a stop hitherto used at the object end of the photoheliograph was removed, so as to admit more light; and the instrument was put into connexion with the necessary clockwork, and thus made to move so as to allow for the motion of the earth. A very success-heated, and this happens rather frequently, part of the gaseous ful photograph was then obtained by one minute's exposure.

The most interesting astronomical phenomena attending a total eclipse of the sun are the formation of a luminous halo, or "corona," around the darkened body of the moon, and the appearance of certain brilliant luminous protuberances at and near its edge. These protuberances, when numerous, regular, and connected together, constitute what are called "Bailey's Beads." Mr. De la Rue, on the recent occasion, succeeded in photographing the luminous protuberances at certain stages, and also that part of the corona nearest to the moon's disc. The corona appeared first on the eastern, or advancing, edge of the moon, and then, as the moon glided onward, on its western edge, so as to constitute a complete halo. It was white, and radiated in all directions, in a manner reminding the spectator of the aurora borealis. The luminous protuberances, which were very numerous and variously shaped, were much more brilliant than the corona. Some of them were white, others golden others of a faint rose colour.

2. After all the volatile products have distilled off, common coke remains in the retort. If the sides of the retort have been over

and liquid products are decomposed, depositing an exceedingly hard crust of carbon on the retort. This carbon has been advantageously substituted by Bunsen for the platinum element of Grove's battery.

3. The liquid products consist of water containing ammonia and ammoniacal salts, which are either used as manure or employed in the preparation of salts of ammonia, and a thick semiliquid substance called gas tar. The nature of this tar was formerly so little understood that it was burnt as fuel under the gas retorts! The constituents of coal-tar are exceedingly numerous,

These are the dimensions given by Mr. De la Rue. M. Petit, however, the director of the Observatory of Toulouse, has published a measurement of some of these protuberances, according to which some of them were not less than 20,000 leagues wide, and 80,000 leagues long. M. Petit regards them as being. not mountains, but enormous clouds, floating in the vast atmosphere of the sun. He declares that two of them which he observed were separated from the disc of the sun by an interval of at least 6,000 leagues

and many of them have not yet been completely investigated; it will be sufficient to enumerate the most important.

I. Carbolic acid or phenylic alcohol.-This body may be separated from the coal-tar by means of lime. In its impure state it is liquid, and goes by the name of creosote, of which the uses are well known; when perfectly pure and free from water, it is a beautiful white crystalline body.

II. Ammonia, and various alkaline bodies resembling it, viz.,picoline, quinoleine, pyrrol, and aniline.-Aniline may sometimes be extracted from coal-tar, but it is generally present in too small a quantity to be obtained advantageously from this source. III. Various compounds of carbon and hydrogen, both liquid and solid, viz., liquid,-benzin, toluene, cumene; solid,-napthalin, chrysene, and pyrene. Of these bodies the most important is benzin, which is extracted in the following manner:-The coal-tar is submitted to fractional distillation, and the more volatile distillate is set aside from the heavy oil, which remains in the retort. This last is principally used for preserving railway sleepers and wood which is exposed to decay, on account of its powerful antiseptic properties, due principally to creosote. The light oil contains benzin, toluene, cumene, etc. If this be distilled, and the product passing over at about 176.5 deg. Fah. be collected apart, all the benzin will be obtained, and may be purified by rectification. Toluene, which has the next lowest boiling point, does not boil till 237 deg. Fah., so that the separation is almost complete. Pure benzin is a limpid, colourless oil of rather agreeable odour. It is lighter than water. Submitted to the cold it solidifies in crystalline laminæ. It is extensively used for dissolving gutta-percha, for manufacturing varnish, for cleansing clothes, gloves, etc., from grease, as a combustible for lamps, and finally for making nitrobenzin, from which aniline is prepared.

When benzin is added in small quantities to warm fuming nitric acid, the liquid, on cooling, deposits nitrobenzin as an oil. The product is washed with water and carbonate of soda, and rectified at 415 deg. Fah. Nitrobenzin is a yellowish liquid, of sweet taste and highly agreeable odour, resembling oil of bitter almonds, for which it is most economically substituted in perfumery, and sometimes in pastry.

When nitrobenzin is acted upon by zinc filings and sulphuric acid, or by sulphide of ammonium, it is converted into aniline. Aniline was discovered, in 1826, by Unverdorben, and named by him crystallin. It was subsequently investigated by Runge, who called it kyanol, and by Fritzsche, from whom it received its present name. It may be prepared in a variety of other ways; for instance, by heating indigo with potash. Aniline is a colourless liquid, heavier than water, of a strong aromatic odour, which is not disagreeable when it is pure. It is but slightly soluble in water. It combines with acids, and forms salts, just like potash and soda, and belongs to the class of bodies called alkaloids, such as nicotine from tobacco, and closely resembles ammonia. Indeed its formula is represented by ammonia (which consists of one atom of nitrogen and three of hydrogen), wherein one atom of hydrogen is replaced by one atom of a compound radical, i.e. a compound body playing the part of an element. The radical in this case is phenyl, a compound of carbon and hydrogen. We are indebted to an English chemist, Mr. W. H. Perkin, for the discovery of the aniline dye. It is prepared in the following manner :-Impure commercial sulphate of aniline is disolved in water and mixed with a certain quantity of solution of bichromate of potassium, and the whole is allowed to stand for ten or twelve hours. The black, pulverulent deposit thus obtained is thrown on a filter, washed with water, dried at 212 deg. Fah., and finally digested with coal or naphtha to dissolve out a brown resin which is always present. The colouring matter is now dissolved in wood spirit, which, by gentle evaporation, deposits the dye in a state of purity.

To dye stuffs of a lilac or purple colour, a strong alcoholic solu. tion of the dye is added to a weak boiling solution of tartaric or oxalic acid, and when the liquid is cold, the silk or cotton fabric is immersed in it.

To dye woollen, it is better to add sulphate of iron to the liquid, and then to boil the whole. The fabric is washed, first with pure water, and afterwards with soap and water. The aniline dyes are characterized by their great beauty and durability, and at the same time by their colouring powers, very small quantities being sufficient to dye a large amount of material.

until it becomes saturated; it dissolves out carbonate and oxalate of ammonium, phosphate and carbonate of calcium, etc., and is therefore extremely valuable as manure, or for preparing phos phates of ammonia. The residues are again weshed with fresh quantities of warm hydrochloric acid, and finally with water. They consist of uric acid mixed with small quantities of sand and clay.

When uric acid is added by small portions to nitric acid of sp. gr. 1. 4, care being taken to wait each time till all effervescence has ceased before adding a fresh quantity of uric acid, a substance called alloxan is gradually deposited from the liquid in small granular crystals, which must be separated from time to time from the acid mother-liquid. The crystals are drained from acid, dissolved in water, the solution is kept near the temperature of ebullition, and a solution of carbonate of ammonium added drop by drop. Carbonic acid is evolved with effervescence, the liquid assumes an intense purple colour, and finally becomes thick, owing to the deposition of reddish-brown crystals of murexide. Carbonate of ammonium is still added, till the liquid smells feebly of ammonia; the mother liquid is then decanted, and the crystals are washed with water till the wash waters become of a deep purple colour.

Murexide may also be prepared by directly adding ammonia, in small portions to avoid heating, to the solution of uric acid in nitric acid. The liquid deposits crystalline murexide on cooling. This method, however, only succeeds under certain conditions, the exact nature of which is not well known.

Murexide crystallizes in transparent flat four-sided prisms. These crystals appear by transmitted light of a fine garnet-red colour; by reflected light they appear on the two broad sides of the prism of a magnificent golden green, like the wing cases of a golden beetle, while the narrow sides are reddish brown, or, in a strong light, greenish. Their powder is red, and under the bur. nisher assumes a green colour, of a metallic lustre. Murexide is but very slightly soluble in water, to which, nevertheless, it imparts a magnificent purple colour. In potash it dissolves with intense blue colour, forming purpurate of potash.

Murexide furnishes brilliant carmine, purple, orange, or yellow dyes, according to the mordant or metallic salt with which it is employed. Carmine or purple tints are best produced by using salts of mercury as mordants, and orange or yellow by salts of zinc. A purple colour is imparted to silks by steeping and constantly stirring the fabric in a mixture of solutions of murexide and corrosive sublimate. The tint varies in intensity according to the strength of the bath and the time the fabric is immersed. The dyeing of woollen is attended with more difficulties, since the wool exercises a reducing action on the murexide; it is necessary to employ corrosive sublimate and oxalic acid, or sulphate of mercury and tartrate of potassium and mercury, with the dye: and to these an oxidizing agent, such as chlorine water or bleaching powder, must be added. The woollen is finally dyed with a solution either of pure murexide or of murexide and oxalate of

sodium.

Another method consists in immersing the fabric in a colourless solution of uric acid in nitric acid, and exposing it to heat in a current of hot air, or over a heated metallic surface, and finally fixing the colour by means of a bath of either mercury, or zinc salt.

Murexide, it appears, is also capable of forming "lakes" almost insoluble in water, and possessing very vivid tints.

Such, then, is a slight sketch of the methods by which these magnificent dyes are produced in such a wonderful manner from substances with which their connexion would appear at first sight incredible.

PICKLING AND POISONING THE THAMES. THB condition of the Thames this summer, owing to the rain-fall having been more than double what it was in 1859, and larger still in comparison with that of 1858, has been unusually pure. In the month of June its water contained, at the most, only thirty-two grains of dissolved substances per gallon, of which from two to four grains were organic matter; whilst last year, at the same time, it contained ninety-four grains, and the year before one hun dred and forty-three grains per gallon, of which from eleven to twelve were organic matter. In August and September of that Murexide, or the guano dye, was so-called by Liebig from its year, the impurities it held in solution amounted to from three probable identity with the ancient Tyrian purple, which is sup-hundred to four hundred grains per gallon, and it was most horribly posed to have been prepared from a shell fish named murex. offensive. Scheele discovered, as early as 1776, that the solution of uric acid Whenever the river-water contains an unusually large amount in nitric acid reddened the skin, and left a purplish-red residue of dissolved impurities, the excess is found chiefly to consist of on evaporation; but Prout, in 1818, first prepared crystalline common salt and sulphate of soda, as if, in the absence of upland murexide, to which he gave the more appropriate name of pur-floods, the tidal sea-water penetrated far up the river; but there purate of ammonia. It has since been investigated by Liebig, and Wohler, and others. To prepare murexide, it is first necessary to obtain uric acid. For this pupose guano, in which uric acid is contained as urate of ammonia, is digested with dilute hydrochloric acid; the solid residue is then allowed to settle, and the clear liquid decanted. This liquid is again applied to fresh guano

is also to be taken into account the fact that the contents of the sewers discharged into the river are much concentrated, or but little diluted, in comparatively dry seasons. It has been supposed, indeed, that it was this direct admixture of an undue proportion of sea-water with sewage water, both in an unusually concentrated state, and acted upon by a high temperature, which led to

the noisome decomposition noticed in recent years in the Thames. How far such a conclusion is in favour of, or militates against, a plan for the purification of the Thames, which has been suggested and patented by a Mr. Kotulla, we are not prepared to decide. This method consists in increasing the specific gravity of the river-water by dosing it with common salt in large quantities, Bo that, either becoming of the same density as sea-water, it will easily intermix with it, or, becoming heavier, it will run away beneath it, at all times, instead of, as now, being lifted up and held back by the marine supply. He further advises the addition of half a ton of alum to every one hundred tons of salt. The dosing he recommends to take place at the ebbing tide, to be continued for a few days at first, and then only occasionally, as required. But what follows is of more startling interest. A short time since it was recommended, for the purpose of deodorizing the London sewage, or the Thames itself, to add to it in certain quantities a particular solution of perchloride of iron, patented by a Mr. Dales. Dr. Letheby has found that certain samples of this solution contained two hundred and ninety-six grains of chloride of arsenic per gallon! So that for the purpose of complete deodorization no less than two hundred and twenty-seven pounds of that highly poisonous substance would be poured, with the perchloride of iron solution, into the Thames every day. The quantity necessary for one million gallons of sewage would contain enough arsenic to kill two thousand six hundred and forty persons; and, seeing that eighty millions of gallons of sewage enter the Thames every twenty-four hours, Dr. Letheby thought it right to "warn against the use of so frightfully dangerous a liquid.”

However, the most timid Londoner need not take alarm. Drs. Hoffman and Frankland find that the samples of perchloride examined by them contain only one hundred and twenty-five grains of chloride of arsenic in the gallon; but, what is of more consequence, they show that if the quantity were always what Dr. Letheby found, it would be rendered innocuous by being mixed with the sewage matter. Sewage matter is highly alka line, and, when mixed with the perchloride of iron solution, gives rise to a precipitate of the hydrated peroxide of iron, which is the most complete antidote for arsenic with which we are acquainted, instantly uniting with it to form an absolutely insoluble and innocuous compound. In fact, sewage-water so treated and then filtered, contained not a trace of arsenic, nor even of iron itself. The use of the perchloride to deodorize the sewage in filtering reservoirs by the side of the river, and then allowing the purified water to pass into the stream, could, therefore, do no possible harm to the river-water.

But, moreover, suppose the solution to be thrown directly into the Thames, there would then be only one grain of arsenic (ren dered insoluble by its union with the iron) in three thousand grains of the solid sewerage substances. This, if diluted by the whole water of the river, would assuredly do no harm. But, suppose it were all dissolved, and, therefore, in a state ready to act poisonously, still, as one thousand millions of gallons of water pass through London daily, there would be only one grain of white arsenic in one thousand four hundred and fifty gallons. The water at Wiesbaden, taken by invalids, contains one grain of white arsenic in one hundred and sixty-six gallons. Suppose, therefore, an individual to consume even a gallon of water daily in beer, bread, and other food, it would take him ten years to have imbibed a poisonous dose; and it would take three and a quarter tons of coal to evaporate enough of old Father Thames to yield the same poisonous dose.

It is obvious, therefore, that this arsenicophobia is without foundation. Perchance the introduction of small quantities of arsenic into the Thames might even do good, in the same inscru. table way as the arsenic fumes, produced in brass-founding, have been thought, perhaps, to account for the remarkable freedom of Birmingham from cholera in its several visitations to this country.

THE STEEL SEA-BEACH OF TARANAKI. An instance, as remarkable as any which could be named, of the discovery of the true character of some useful product of nature, after its having lain long unknown and unemployed by man, though close beneath his hand, has just occurred in the district of Taranaki, near New Plymouth, in New Zealand. For about seventeen miles along the coast of this district there is nothing to be seen but a dull smooth beach, of a dreary black hue, which is deepened by contrast with the snowy foam. This beach is half a mile wide at low water, and its constituent particles or grains have a slight metallic lustre, and are so small as to resemble fine gunpowder. They are much heavier than ordinary sand, whence the beach is very much smoother than our own sandy sea-boards. So smooth and glassy is it, that nothing that the waves can wash on to it can remain on it. Its black monotony is therefore unrelieved by shells or sea-weed,-much to the increase of its dreariness of aspect.

Strange to say, this long and naked strand consists of myriads of tons of steel, in a granular form,-pure, excellent steel, of very fine quality. Yesterday this black dust was thought to be

valueless, and was trodden under foot by the careless native, and regarded by the unconscious colonist as of no more worth than the materials of which ordinary sea-beaches are composed. To-morrow, it will be knives, needles, chisels, swords, bayonets, gun-barrels, implements of peace or weapons of war, and will be bought and sold for many pounds per ton.

The

The origin of this wonderful tract can only be conjectured. supposition which has most to recommend it is, that volcanoes containing pure steel in a state of fusion must have existed near this spot; that the sea at some time broke in upon the molten mass; that an eruption was thus caused which sent enormous clouds of metallic particles into the air; that these particles fell back into the sea, and have thence been washed on to the shore, layer after layer, until the present vast beach has been formed. Nothing resembling these metallic particles is known to exist elsewhere in nature. The native steel which is found at times in mining, and which differs materially from ordinary iron ore, constitutes the nearest approach to them. It occurs in the shape of "button ingots" with a finely striated surface, and is supposed to have been produced by "the spontaneous combustion of seams of coal in the neighbourbood of ferruginous deposits,"-the burning scum acting as a smelting-furnace, the adjacent ore being smelted in it, and the natural steel thus formed having gradually cooled, assuming the rounded form, whence the name, "button ingots." Something of the same sort is what is supposed to have taken place with the Taranaki metal; except that, instead of the Taranaki metal having tranquilly cooled, the breaking in of the sea is supposed to have caused a sudden interruption, and a violent explosion, which burst the metal into comminuted particles.

When this steel-sand is placed in a crucible or retort, and reduced to a state of fusion, it can be immediately moulded into ingots of steel. For it is not simply iron requiring to be manufactured into steel,-it is ready-made steel.

In order to a due appreciation of the value of the Taranaki sand, it is necessary to understand the process by which iron is converted into steel. Steel is iron chemically combined with carbon or charcoal. There very often exists a mechanical mixture of carbon with iron; but for the making of steel a more subtle, because chemical, combination of the two elements must take place. This is accomplished by the process of "cementation." The difference between iron and steel may be easily perceived by comparing the places of fracture of a broken bar of each. The former will be found to present a fibrous, and the latter a grann lated or crystalline structure. The difference in character is even greater than that in appearance; it is the difference between a piece of iron wire and a needle of the same thickness; or between a piece of iron hoop, and the fine Damascus sword-blades, so famous in history and oriental romance, pliant enough to be twisted into a knot, tough enough to be driven through a helmeted head, and keen enough to sever the lightest fabric. For the process of "cementation," the best iron ores are chosen, and certain districts are celebrated for yielding good steel iron, such as the Danemara, about thirty miles from Upsal, in Sweden, the Wootz in India, the Forest of Dean and Ulverstone, in England. The ore having been smelted and converted into soft iron bars, these are buried in some carbonaceous substance, usually wood-charcoal, the whole is tightly compacted together, and covered with clay so as to exclude the air. The furnace in which they are placed is then fired, and continued at a given heat for a certain time. During this heating, carbon is gradually absorbed by the iron, until throughout the substance of the bars a crystalline formation takes the place of the preceding fibrous arrangement. When the bars are drawn from the furnace, they are covered with blisters, or air-bubbles; hence they are named "blistered steel." In this state the steel is fit for the manufacture of rough articles; but other processes are necessary to perfect it either as "shear-steel" or "cast-steel." For the former, the bars are submitted to continual "tilting" or hammering, to attenuate them into rods, which are then clamped into bundles, heated, and then hammered again into an homogenous mass. For cast-steel the blistered ingots are broken up into fragments and placed in retorts of Stourbridge fire-clay. Great care is taken in making these retorts. The clay is trodden out by the naked feet, by the sensibility of which grits and air-holes are detected, and got rid of. With the steel fragments is mingled a little manganese, and the mouth of the vessel is closed with bottle glass, which meits in the fire and hermetically seals the retort, These charged crucibles or retorts are placed in a furnace, and the steel melted, and poured out, in the form of a glowing fiery liquid, into moulds. The ingots thus made are then ready for forging into any of the thousands of articles for which such metal is used. The tempering, which is done by heating the manufactured article and suddenly cooling it, is an after process, regulated by the degree of hardness required.

From this indication of the labour and expense involved in making iron into steel, the peculiar characteristics and value of the Taranaki sand will be readily understood. It has merely to be fused, aud may then forthwith be moulded into bars ready for forging. It does not require to undergo any of the intermediate

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