and confusion of those to whom they are given, they melt and sink in a lump to the bottom the instant they are immersed in hot tea. Bismuth is also, though rarely, used as a medicine. An oxide of this metal, called pearl white by perfumers, is used by the ladies to make their skins look fair and smooth. It is a very favourite cosmetic, but its use ultimately injures the skin; though those who trust entirely to their toilet for their charms do not mind this, as they know the same art which does the mischief can always repair it for their momentary purposes. It is also liable, which is a much worse fault, to turn black when it comes into contact with sulphuretted hydrogen gas, and with some other substances that are occasionally generated where coal is burned and people crowded together; so that it has happened, that she who went into company the fairest of the fair, has come out of it, to her sad' mortification and dismay, the tawniest of the tawny. MERCURY, OF QUICKSILVER, is a better known and more useful metal than bismuth, and seems to have been familiar to the ancients, who employed it for some of the purposes for which the moderns still employ it. Native mercury has been found in small quantities in Peru. An ore called native amalgam, or mercury and silver, is found in great quantities in the same country, and it has been found in Hungary. There is a third ore, which consists of mercury, muriatic acid, and sulphur. What is called the hepatic ore, a compound of mercury, sulphur, and carbon, also known by the name of cinnabar, is the ore from which the metal is chiefly extracted: it is found in various parts of the world, but Spain and Hungary are the chief places in Europe where it is procured. The mine in the former country is situated at Almaden, and is so prolific that more of the metal has been at times obtained than could be sold. The famous quicksilver mine of Guanca-Velica, in Peru, is 480 fathoms deep, and of such extent

as to have whole streets formed in it, as well as 'a chapel, where religious ceremonies are celebrated,

formerly the only consolation of the thousand naked Indians who were annually driven into the mine to perish by the most miserable of deaths. Those who are obliged to live there are affected by the convulsions, which inhaling mercury never fails to produce; and thousands, perhaps millions, of poor Indians fell a prey to the ruthless avarice of the Spaniards. Things are somewhat better now; but the manner in which the United States of America have outstripped the Spanish colonies in the same country, though blessed with a better soil, is a triumphant proof of the utility of justice, and one of the strongest recommendations nature ever put on record for men to seek wealth by their own industry, and abstain from oppressing their fellow men.

The following method is employed to obtain mercury from cinnabar in Spain. The ore is divided into three portions: one containing the most metal, the second containing less metal, and the third is the powder which falls from the other two. A furnace is provided, consisting of a long horizontal building, divided into two compartments by a horizontal grating of iron. On this is placed flat rough stones, and on them the second sort of ore is. first laid, which is covered by va layer of the ore containing the most metal, and over this another layer of the second ore is laid; above all comes the third sort of ore made into a sort of bricks with clay kneaded and dried; wood is then kindled in the lower part of the furnace, by which the moisture is first driven off, afterwards the sulphur begins to burn, and the heat of its combustion volatilizes the mercury, which is condensed in a receiver attached to the furnace. It is afterwards separated from the soot by placing both on án inclined plane, when the mercury runs off; a good deal of it, however, still remains with the soot, and is thrown aways with it,noIn

Germany, the mercury is distilled from iron retorts, in which it is put with lime, and is condensed in a receiver constructed for the purpose.

to Mercury thus obtained is of a white colour, somewhat bluer than silver, but so like it that it was called quicksilver. It has no taste nor smell, and is very brilliant. It is distinguished from all other metals by its extreme fusibility, which is so great, that while other metals require the strongest heat of our best furnaces to liquefy them, mercury is always fluid at the common temperature of the coldest climates which man can inhabit. It does not take the solid state till the temperature is diminished to 399 below 0 on Fahrenheit's scale. This circumstance, combined with the fact of its extension by heat being very equable or regular, renders it one of the best known materials for measuring temperature. Thermometers therefore are, in general, constructed of it. Mercury boils when it reaches the six hundred and fifty-sixth degree, and may be distilled over, like water or spirits. This is frequently done to purify it from other substances. Mercury also rises in yapour in small portions at the common temperature of the Latmosphere, particularly in a vacuum. Its vapour is elastic and invisible like air, and possesses such force, that an iron globe in which some of it was inclosed being heated red hot, the globe burst with all the violence of a bomb, and the whole of the mercury was dissipated. Solid mercury extends under the hammer, but to what degree is scarcely ascertained. At Hudson's Bay, by taking proper precautions, it was beat into sheets as thin as paper. The specific gravity of mercury is, when fluid, 13.568, when solid 14.465, there being only gold and platinum which are heavier. At the same time, it vis so extremely divisible, that it -may be strained through the pores bfoleather; and this is frequently done to separate it from other substances. If adulterated, however,

with lead and bismuth, even to onefourth of its bulk, the whole will thus pass and the adulteration remain undetected. Mercury readily combines with most of the metals, forming amalgams. It also combines readily with oxygen, forming two oxides, one black, called ethiops per se, the other red, called red precipitate, or precipitate per se, and which is much used as a caustic, or escharotic, it destroying the skin or flesh. Mercury also combines with chlorine, and forms corrosive sublimate, or deutochloride of mercury, which is used in medicine, and is a most virulent poison, and calomel, or protochloride of mercury. Thus the reader will see that, independent of those various uses he knows of for mercury in its metallic state, such as making barometers and thermometers, silvering mirrors, &c. it forms one of the most powerful and useful, but dangerous medicines man has ever discovered. Mercury is also used in separating gold and silver from other substances; and as this is both a curious and an instructive process, when we come to treat of those metals, we shall describe it.

1

SOUND HAS NO VELOCITY. To the Editor of the Chemist. SIR,-In one of your earlier Numbers you stated the result of some experiments made in Holland, on what you, as well as others, call the velocity of sound. In the last Number of the Philosophical Magazine, I observe there is an account given of some experiments by Dr. Gregory, which are styled by this philosopher to be on the velocity of sound. Now, Sir, with your permission, I will endeavour to show your readers that this is an absurd mode of speaking, and that sound has no velocity. Dr. Gregory, as well as the people he employed, looked at their watches or other instruments for measuring time, when they saw a flash, and they marked by these instruments the interval which elapsed before they heard sound, Sound, therefore, was what they heard, the sensa

tion they felt, and how that travelled from the seen flush, when both existed in the same mind, the learned doctor has not condescended to tell us. In fact, Sir, sound means sensation in us, and not its cause; in the same way as sight, or vision, means our sensation, and not our eyes or the light which impinges on them. We' never hear of the velocity of vision, because philosophers ascribe vision to light, of the motions of which we do hear; and we only hear of the velocity of sound, because they have not found out a substantive appellation to which they may attribute this sensation. Their prosopopaia was at fault when the theory of sound was constructed; and they could not find any pretty little name by which to raise the motions of the air to the dignity of a separate being. The cause of sound is supposed to be vibrations of the atmosphere, affecting the tympanum of the ear, and thus producing in us the sensation. There may be a rate of velocity at which these vibrations circulate; but there can be no more velocity in the sound than in the mind, where alone it is felt, and where alone it exists. This is, therefore, a very incorrect mode of speaking, and I object to it as leading to incorrect conceptions and incorrect conclusions. When scientific men, led astray by their own uncouth phraseology, set about making experiments to ascertain the time which elapses from the moment powder flashes from a gun, and the exciting of a sensation of sound at a certain distance, by supposing the sound is what travels they are obviously led to conclude that it travels at the same rate, let it, namely, the sound, be produced by whatever it may. If, however, there is no sound to travel, but vibrations of the air to circulate, it seems natural to suppose that these vibrations will move quicker or slower as the first impelling cause is quicker or slower; and thus that the vibrations caused by the sudden and rapid flash of exploding powder would spread with somewhat great

er rapidity than the waves of air set in motion by the tinkling of a bell or the stroke of a hammer. I observe, indeed, in some of Dr. Gregory's experiments, that the sound is said to have had rather a greater velocity when the bell was tinkled than when a gun was fired; but Dr. Gregory makes an allowance of one-fifth of a second, or nearly 220 feet in a second, for the time that elapsed between one man hearing the clapper of one bell and sounding another which he held in his hand, ready for the purpose. In such experiments, I consider an allowance of this kind, as well as the circumstance which made it necessary, to be of such a nature, depending, as that did, altogether on the quickness of perception and execution in an individual, as to vitiate the whole result. There is no proof, therefore, in these experiments, that the vibrations of air, set in motion by sounding a bell and by exploding powder, always move with the same velocity. In the early part of his paper, Dr. Gregory gives the results of the experiments of other persons, eminent philosophers, too, on what they also are pleased to call the velocity of sound, and they vary between 1474 and 1107 feet in a second. The doctor's own experiments give results varying between 1112 and 1094 feet in a second, which seems to show that precision is not yet attained. This varying result, Sir, tends to confirm the supposition, that the vibrations of air circulate with a different degree of rapidity as the impulse which sets them in motion is greater or less. Having thus shown, Sir, I trust, that the phrase Velocity of sound" is a very erroneous one, and that using it leads men from a consideration of the problem to be determined, namely, The velocity with which the cause of our sensations of sound, supposed to be vibrations in the air, moves, I hope Dr. Gregory, in continuing his experiments, and other philosophers who may think the same subject worthy of their attention, will not again

66

Your obedient servant,

BISHOP BERKELEY'S GHOST. London, July 1.

We have inserted this commu→ nication of our Correspondent, because we do entertain an opinion that many scientific modes of expression are metaphysically and philosophically incorrect. We cannot, however, congratulate our Correspondent on his possessing the acuteness and knowledge of the great man whose name he has assumed. Bishop Berkeley's Ghost should have known, like the bishop himself, that it was long ago shown, that whatever may give the first impulse to the air, the vibrations, to use his language, or, to use the language of men of science, the sound always travels at the same rate. Whether or not the fact of its requiring equal times to excite at equal distances the sensations of sound produced by the blow of a hammer and exploding gunpowder, is consistent with the theory of vibrations producing sound, when in general vibrations extend with a rapidity in proportion to the first impelling cause, we will not determine; but Bishop Berkeley's Ghost should have known that this fact was established by the experiments of Sir Isaac Newton. We beg that our metaphysical Correspondent, therefore, will make himself better acquainted with the facts of science before he again honours us with his crude suggestions.--ED.

ric acid, or sulphuretted hydrogen gas. This kills by coming in contact even with a small part of the skin. M. Chaussier, who was the first to make known this phenomenon, put the foot of a rabbit into a bladder containing this gas, which had no communication with any other part of the body, nor was it possible for the animal to breathe it; he died, however, in a very few seconds. The least quantity of this gas introduced into the air we are to breathe causes instant death. A horse which breathes air, of which the eight-hundredth part only of its volume is composed of this gas, dies instantly. This gas, and the hydrosulphuret of ammonia, which is almost as virulent a poison, are both disengaged from the putrid fermentation of common sewers, stagnant waters, &c. Must we not repeat, then, we that bear "charmed lives."

POISON IN THE VIOLET.

M. Boullas has announced, that he has discovered an active, acrid, bitter alkaline principle in the violet, similar to emetine, and which he proposes to call violine. It is extracted from all parts of the plant, and is said to be extremely poisonous.

JALAPINE.

Mr. Hume, jun. of Long-acre, has discovered a vegetable alkaline principle in jalap, which he proposes to call jalapine. It is without any perceptible taste or smell, and heavier than morphia, quinina, or other substances of this class; it is scarcely soluble in cold water, and only sparingly soluble in hot ether.

PERKINS OUTDONE, OR

NEW INVENTIONS. A SMALL vessel, the machinery of which, furnace and all, occupied only three feet in length and two and a half in width, and without a boiler, was witnessed, on the 10th ultimo, at Philadelphia, driving a a common ferry-boat, with twelve passengers, at the rate of eight miles an hour. It is the invention of Mr. Hawkins; and if the cylinder, which is only seven inches in

To the Editor of the Chemist. Leeds, June 29. SIR,-In perusing_your Chemist of the 19th June, I see you have given your readers a plan of a gasometer, purporting to be an invention of Mr.Tait's, of Mile-endroad. A particular friend of mine has had one of the same construction in actual operation for some time. Will you, through the medium of you Chemist, inform your readers at what time Mr. Tait's gasometer was first erected, that we may give to each individual the honour that is due to him for such an important invention.*

I am, Mr. Editor,
Yours respectfully,
J. R.

CHEMICAL SOCIETY. To the Editor of the Chemist. SIR,-In consequence of the notice inserted in The Chemist of Saturday, June 26, a number of gentlemen assembled at my house, for the purpose of establishing a Chemical Society; but it being considered by then, that many others who have professed themselves friendly to the cause would be prevented from obtaining the address in time to attend, it was therefore proposed to adjourn to Thursday, 15th July, when the presence of every gentleman favourable to the intended Society will be desirable.

Any information respecting the Society I shall be happy to communicate, either through the medium of your valuable Journal or by post.

I am, Sir, Your obedient servant, W. JONES. a *We hope Mr. Tait will make our Publication the medium of conveying the intelligence desired to our Leeds Correspondent.

Mr. Jones is quite right in supposing his former note did not reach us in time.-ED.

TO MAKE FIRE FROM WATER.

POUR a little clean water into a small glass tumbler, and put one or two pieces of phosphoret of lime into it; in a short time flashes of fire will dart from, the surface of the water, and terminate in ringlets of smoke, which will ascend in regular succession.

TO CORRESPONDENTS. R. C. may rely on our discretion. His manuscript shall be carefully destroyed.

Chemicus Ignoramus in our next. We should, at the same time, beg leave to ask him, if he is sure he has stated all the circumstances which could have an influence on the phenomenon he describes?

A Subscriber and Reader is informed, that we have never ourselves had occusion to put the practice we described to the test of experiment; but it is recommended by such excellent chemical authority, that at present we have no doubt of its efficacy. It is indispensible, however, that the sulphuric ether should be quite pure, and that it should used. Taking this precaution, we are be well washed with water before being disposed to think Pelletier, Thompson,

and Ure have not all asserted what is incorrect.

We are much obliged by the ready manner in which A* D* has taken our hint; and as we intend to give rather an extensive account of distillation, we will, with his permission, make use of the information he has given us in our

own way.

We shall take an early op

portunity of profiting by the other part of his offer.

Problematicus in our next.

Anti-Stahl's letter is very well written, and very flattering to ourselves. It will be inserted in our next; but we could have wished its object had been more definite.

*

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

London: Published by KNIGHT and LACEY, 55, Paternoster-row.-Printed by B. Bensley, Bolt-court, Fleet-street.