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ter, and to this add fourteen fluid ounces of ether, and shake them well until they are mixed. Place the mixture in a water or saudbath, about the temperature of 200", and distil over 12 fluid ounces of ether from a large retort into a cooled receiver. The ether is then rectified. In this state, however, it is said still to contain some alcohol, which prevents it dissolving caoutchouc, and this must be separated by washing. This is done by adding about nine or ten fluid ounces of distilled water to the ether, and shaking them well together in a close vessel. They must then be allowed to remain for some time at rest, when the water will' subside to the bottom, and the ether remain floating on the top. Pour it off and it is fit for the use of our Correspondent; buthemust be careful to keep it in a close stopped vessel. He will, however, find that this is an expensive method; and a cheap one of accomplishing that which he inquires after, has long been a desideratum. Whether or not Mr. T. Hancock's method, mentioned in No. XIX. of the Chemist, be a cheap one we cannot decide.

METHOD OF PREPARING OXYGENATED MATCHES.

Three parts of chlorate of potash and one of sulphur, reduced to powder separately, (for if pulverized together they will detonate) are to be mixed on paper, and care must be taken even in the mixing not to produce any friction or percussion. A small quantity of gum water is added to give consistency to the substance; and also a small; quantity of Ij/copode, or wolf's-claw moss, to promote the combustion. It is coloured red with cinnabar, and blue with indigo. The matches are made round, very fine, and are dried in an oven or stove; and one of their ends'only is covered wffh a small quantity of the above mixture. To dry them, the other end is stuck in a box filled with earth or sand. To procure an instantaneous light with • these

matches, which are now sold at every chemist's shop in themetropolis, it is only necessary to plunge the end into concentrated sulphuric acid, and immediately withdraw it. The sulphur, previous to mixing, should be washed to free it from sulphuric acid, and well dried.

TO PREPARE ALOES PJLLS WITH MYRRH.

1MLI.UI..E ALOES CUM MYKRHA.

This preparation being an excellent cathartic, and much in use under the name of /)illum nifi, we shall give the mode of preparing them from the Pharmacopoeia. Take of extract of spiked aloe, two ounces ; of saffron and myrrh, each, an ounce; and of simple syrup, a sufficient quantity. Rub the extract and the myrrh separately to powder, then beat the whole together, till the mass is uniform. It is taken in doses of ten to twenty grains, both as a stimulant and cathartic.

'1 ■—j . {V*.

TO PREPARE PURE CARBON.

Take the whitest susrar which can be procured, and of the finest crystals; dissolve it in water, and again crystallize it by evaporation, at a temperature scarcely higher than that of the atmosphere; distil the stfgar thus crystallized by a red heat. There will first come over a fluid resembling water, which is afterwards mixed with pyromucuous acid and empyreumatic oil, and a bulky charcoal remains in the retort. When these matters have done coming over, increase the heat to a point that would melt steel, and keep the charcoal exposed to it for about an hour. It will then' he found very brilliant, hard, and difficult to burn. Ifthe opeiatioh has been well performed, the charco.al will grow red when exposed to heat, without producing the smallest flame, and as soon as it'iS'withdrawn from the furna'ee it is extinguished. A current of air, also, will extinguish it, and it can only be consumed by oxygen gas, and if this is withdrawn, it becomes immediately black. ^ i- '-'■ *- *• • QUERY.

The best mode of preparing the different colours wliicli are exposed in the windows of many of the surgeons and chemists.

I remain, R.S.F. .. '■——— '—.'i —,—,

ANSWERS TO QUERIES.

To the Editor of the Chemist.

Sir,—Your correspondent, "A Constant Reader," in No. 18, has two very strangely united questions. What has tallow to do with onions, Sir? Is he some gentleman who wants to set up a shop for making savoury soups for the poor in winter? I see no other possible application of fat and onions, and confess I am much surprised how any head conceived the two things together, or how you, Mr. Editor, came to admit such an absurd mixture into your pages. I would answer your correspondent's questions if I knew how; but I have never heard or read of the juice of onions being prepared or concentrated. I know experiments have been made to analyse this vegetable, but as the roots themselves keep from year to year, from hardest to harvest, and are sent many thousand miles, nobody but your correspondent has ever thought of expressing the juice, and concentrating it for preservation. As to yourcorrespondent's second query, Sir, I must observe th&t fat is a general name for several kinds of solid oily substances found in animals, while tallow is the name of a particular species of fat. What he means by the best kind of tallow, I am at a loss to know. Does he mean the best tallow for candles; 'or the best suet for puddings? If he is explicit as to what he means, , I *m sure the pages of the Chemist will supply him with an, answer; , but, as his query at present stands, it cannot be answered. Wishing you more discretion) Mr. Editor, i than to admit such communications, and your correspondent ,,,«nflre precision, ~<r>% avk i, J remain, yours, .5ffii)W.i li ..■ .I..-. Castigator. Tower, July 15. • , .| . ;i

Mr. Editor,—In a reply to a query in your 19th No. as to a cement or putty which is not attacked by sulphuric acid, I beg leave to refer the querist to No. 2 of your own work, page 19. The lute, Sir, there recommended, called the fat lute, resists the action of sulphuric acid, and is employed on a large scale in the muriatic acid manufactory,and in operations where sulphuric acid is used, to lute vessels. It answers perfectly well. I am, Sir,

Your obedient Servant, T. S.

London, 31 July 1824.

Mr. Epitor,—I observe in a iale Number of the Chemist an article on Mr. Perkins' invention of a steam gun, and being quite a novice in the valuable science of which you are a patron, I make free to ask a question or two in explanation. It is stated in the above named article, that, at the pressure of forty atmospheres, a ball is expelled from a gun with velocity equal to a field charge of powder, and that, at forty-five atmospheres' pressure, a ball strikes the target with force sufficient to liquefy the lead. Now, I understand, that heat alone can change metal from a solid to a liquid state, and will you be kind enough to inform me by what process in this experiment the lead is heated to so great a degree as to cause liquefaction. Is it by the heat of the gun-barrel caused by the steam,—the velocity with which it passes through the air,—or the resistance afforded by the target? Your kindness, in attending to these (perhaps ucscientific) queries, will be duly appreciated by, Sir,

Your admirer, R.C.

All these circumstances contribute to the effect, but it is chiefly due to the last. Air, when suddenly compressed, as is well known, gives out so much heat as to set tinder on fire; and it is the compression of the lead that melts it. It is well known that lead, as well as iron, may be healed by being hammered, and the force of striking against the target is only a more vigorous hammering. Ed.

CHEMICAL SOCIETY.

To the Editor of the Chemist.

55, Great Prescot-street,
Goodman's -Holds.

Sir,—I beg leave to inform yon, that at a former Meeting of the friends of the Chemical Society, a Committee was appointed, for the purpose of framing the laws and regulations, which being now completed, they avail themselves of your polite offer to make their proceedings public, through the medium of your useful and valuablePeriodical; and to inform those gentlemen who may wish to become the founders, that a Meeting will take place here on August 12th, his majesty's birthday, for the purpose of electing and installing the officers, and establishing the Society.

Gentlemen who may be inclined to attend, are requested (if convenient) to send their names and addresses to me, on or before the 11th instant.

I am, Sir,

Your most obedient servant,
W. Jones,
Sec. Pro. Tern.

NATURAL HISTORY. M. Cuvier lately preseuted a Report to the Academy of Sciences on the state of natural history, and the increase of our knowledge in that department since the return of maritime peace, the details of which are very curious. In 1778, Linnaeus indicated about 8000 species of plants; M. Decandolle now describes 40,000; and in a short time they may probably exceed 50,000. Bull'on estimated the number of quadrupeds at about 300; M. Desmarets has just enumerated above 700, and he is far from considering the list complete. M. de Lacepede wrote, tweuty years ago, the history of all the known species of fish: the whole did- not amount to 1500; the cabinet of the king alone has now above 2500, which is only a small proportion, says M. Cuvier, of what the seas and rivers can furnish. We no longer venture to fix the number of birds and reptiles; the museums are crowded

with new species, which require to be classed. Above all, we are confounded at the continually increasing number of insects; it is by thousands that travellers bring them from hot climates: the Royal Museum at Paris contains above 25,000 species, and there are at least as many more in the various cabinets of Europe. The work of M. Strauss, on the Maybug, shows, that this insect, an inch in length, consists of 306 hard pieces, serving as shells or envelopes, 494 muscles, 24 pair of nerves, and 48 pair of tracheae.

TO PURIFY CORN SPIRIT.

M. Zbize has announced to the world, that a small quantity of chloride of calcium (oxymuriate of lime) moistened with water, added to the wash made from potatoes or grain, the liquid being allowed to subside beforeit is distilled, makes the spirit which results more like brandy. It is freed from the peculiar taste all corn brandies have, and is quite as good as that made from wine. The chloride must be good; and the only way to ascertain the quantity which ought to be employed, is to try with a small portion of the wash.

. TO CORRESPONDENTS.

Electricus in our next.

We are unable to form a precise opinion on the subject mentioned by R. Fuller, but we are sure there is de' niand enough for chemical apparatus to pay those well who are disposed to sell reasonably. Success will, however, depend on personal activity.

Problematicus lias been received; his valuable communication shall be inserted in our next.

%* Communications (post paid) to be addressed to the Editor, at the Publishers'.

Loudon: Published by Knight and LaCey,55, Paternoster-row.—Printed by B.Bensley, Bolt-court. Fleet-street.

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TO DECOMPOSE WATER.

{From a Correspondent.) Mr. Editor,—Having observed that, in No. XIV. of the Chemist, a Correspondent inquires after a means for the decomposition of water, I take the liberty of transmitting you two methods: one isv to decompose it by means of carbon, and the other by galvanism. First, to decompose it by carbon. Let your Correspondent provide himself with a glass retort, A,

to contain water, which he may heat by the lamp, B, or by any other means he pleases; also with a porcelain tube, C C, an open furnace, D, a little pneumatic , trough, F, and a receiver, E, to collect the gas. He must putsome charcoal in small pieces into the tube, so as nearly to fill it, then place this in the furnace, where it must be subjected to a good heat. The retort must be adapted to one end of the tube, and a bent tube at the other end to convey the gas into the receiver. On making the water boil, the steam or vapour passes over and through the charcoal, which when red hot will separate the oxygen of the vapour from the hydrogen. The gas, however, which will pass into the receiver, is not pure hydrogen, but contains a quantity of carbonic acid gas, resulting from the union of the carbon with the oxygen, and is called carbonated hydrogen gas. The other method of decomposing water, by galvanism, is the most convenient for obtaining the two gases separate and pure.

As our Correspondent has sent us another little drawing with his second method, we must postpone it till another Number. It may be useful, however, if we point the attention of the reader to one inference to be drawn from this experiment: this is, that in consequence of carbon at a red heat decomposing water, a small quantity of this tluid, particularly when scattered in drops from an engine, may promote couibustiou rather than retard it. If it be decomposed, it will give oxygen to the tlame, which only makes the conflagration more rapid. To extinguish fire, therefore, either a large quantity of water should be thrown, or some other means taken to exclude the air, and reduce the temperature below the burning point.—Ed.

CHEMISTRY AS A SCIENCE. Art. XXII.

CHROMIUM. MOLYBDENUM. TUNGSTEN. TELLURIUM. COLUMBIUM. TITANIUM. SELENIUM. OSMIUM.

There is fonnd, though in small quantities, at the mine of Beresof, in Siberia, a mineral of a beautiful red colour, with a shade of yellow. It is called the red lead of Siberia, and was used as a paint. In 1797, this mineral was examined by M. Vauquelin, the French Chemist, and found to contain a peculiar acid, till then unknown, with a metallic base. His experiments have since been frequently repeated,

and the base of this acid reduced to a metallic state, by heating it with charcoal. This metal was called chromium. It is very brittle, of a greyish-white colour, intermediate between steel and tin. It is very slightly magnetic, and, for a metal, is very light. It requires a powerful heat to melt it, and is only slowly acted on by aqua regia. It has only been obtained in small quantities by a few eminent chemists, and for the purposes of examination. Nothing more is known of it, and it has been put to no use. Chromium, however, is the colour* ing material of a number of beautiful minerals. The one we have already mentioned is an ore of lead, and the emerald owes its colour to the oxide of chromium, while the spindle ruby derives its tint from chromic acid.

In Sweden, and in other parts of Europe, there is found a mineral somewhat resembling plumbago, though of a lighter colour, and which was long confounded with it. Scheele, however, observed that it was a different substance, possessed of different properties, and thus taught chemists to distinguish them. Plumbago has been already described, and to the other he gave the name of molybdena. This mineral, on being analyzed, was found to consist of sulphur and a peculiar acid, having a metal for its base. The acid is now called the molybdic, and the metal obtained from it molybdenum. In consequence, however, of the difficulty of obtaining it, hitherto it has been procured only in small quantities, and has been put to no use. In fact, by no art has it been found possible to obtain it in any other form than small grains, so that its properties are very imperfectly known. With some other metals it unites readily, and forms brittle alloys. Its colour, even, has not been settled, though this has been the object of numerous and laborious experiments. As the ore, however, may be easily obtained, that industry and skill which have already converted so many apparently useless

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