place of the water; but if you force all the water out, the steam, or a small part thereof, going through R, will rattle the clack, so as to give sufficient notice to pull the handle of the regulator to you, which, at the same time, begins to force out the water from Pp, without the least alteration of the stream; only sometimes the stream of water will be somewhat stronger than before, if you pull the handle of the regulator before anyconsiderable quantity of steam be gone up the clack, R; but it is much better to let none of the steam go off, (for that is but losing so much strength) and is easily prevented by pulling the regulator some little time before the vessel forcing is quite emptied. This being done, immediately turn the cock or pipe, Y, of the cistern, X, on P, so that the water proceeding from X through Y (which is never open but when turned on P, or Pp, but when between them is tight and stanch)—I say, the water falling on P, causes, by its coolness, the steam, (which had such great force just before, from its elastic power, to condense, and become a vacuum or open space,) so that the vessel, P, is, by the external air, or what is vulgarly called suction, completely refilled, while Pp is emptying. Which being done, you push the handle of the regulator from you, and throw the force on P, pulling the condensing-pipe over Pp, causing the steam in that vessel to condense, so that it fills while the other empties. The labour of turning these two parts of the engine, viz. the regulator and water-cock, and tending the fire, being no more than what a boy's strength can perform for a day together, and is as easily learned as their driving of a horse in a tub-gin; yet after all, I would have men, and those too the most apprehensive, employed in working the engine, supposing them more careful than boys.

"In case it should be objected, that the boiler must in some certain time be emptied, so as the work of the engine must stop to replenish the boiler, or endanger the burning out, or melt

ing the bottom of the boiler. to obviate this, when it is thought fit by the person tending the engine to replenish the great boiler, which requires an hour and a half or two hours' time to the sinking of one foot of water, then, I say, by turning the cock, E, of the small boiler, D, you cut off all communication between the great forcepipe, S, and the small boiler, D, by which means D grows immediately hot, by throwing a little fire into B, and the water of which boils, and in a very little time it gains more strength than the great boiler; for the force of the great boiler being perpetually spending and going out, and the other winding up or increasing, it is not long before the force in D exceeds that in L; so that the water in D, being depressed by its own steam or vapour, must necessarily rise through the pipe, H, opening the clack, 1, and so go through the pipe, K, into L, running till the surface of the water in D is equal to the bottom of the pipe, H. Then, steam and water going together, will, by a noise in the clack, I, give suffi cient assurance that D has discharged and emptied itself into L, to within eight inches of the bottom; and inasmuch as from the top of D to the bottom of its pipe, H, is contained about as much water as will replenish L one foot. Then you open the cock, I, and re-fill D immediately, so that here is a constant motion, without fear or danger of disorder or decay. If you would at any time know if the great boiler be more than half exhausted, turn the small cock, N, whose pipe will deliver water, if the water be above the level of its bottom, which is half way down the boiler; if not, it will deliver steam. So, likewise, it will show you if you have more or less than eight inches of water in D, by which means nothing but a stupid and wilful neglect, or mischievous design, carried on for some hours, can any ways hurt the engine. And if a master is suspicious of the design of a servant to do mischief, it is easily discovered by these gauge-pipes; for if he come when the engine is at work, and find the surface of the water in L below the bottom of the gauge-pipe, N, or the water in D below the bottom of G, such a servant deserves correction: though, three hours after that, the working on would not damage or exhaust the boilers. So that, in a word, the clacks being, in all water-works, always found the better the longer they are used; and all the moving parts in our engine

being of like nature, the furnace being made of Stourbridge or Windsor brick or fire-stone, I do not see it possible for the engine to decay in many years; for the clacks, boxes, and mitre-pipes, regulator and cocks, are all of brass, and the vessels made of the best ham mered copper, of sufficient thickness to sustain the force of the working the engine. In short, the engine is so naturally adapted to perform what is required, that even those of the most ordinary and meanest capacity may work it for some years without its receiving any injury, if not hired or employed by some base person on purpose to destroy it."

(To be continued.)

MUSICAL BAROMETER. A GENTLEMAN at Burkli, by the name of Ventain, not far from Basle, in Switzerland, invented, some years ago, a sort of musical barometer, which has been called in German, wetter harfe, weather harp; or riesen harfe, giant harp, which possesses the singular property of indicating changes of the weather by musical tones. This gentleman was in the habit of amusing himself by shooting at a mark from his window, and that he might not be obliged to go after the mark at every shot, he fixed a piece of iron wire to it, so as to be able to draw it to him at pleasure. He frequently remarked that this wire gave musical tones, sounding exactly an octave, and he found that any iron wire, extended in a direction parallel to the meridian, gave this tone every time the weather changed. A piece of brass wire gave no sound, nor did an iron wire extended east and west. In consequence of these observations a musical barometer was constructed. In the year 1787, Captain Haas, of Basle, made one in the following manner: Thirteen pieces of iron wire, each 320 feet long, were extended from his summer-house to the outer court, crossing a garden. They were placed about two inches apart; the largest were two lines in diameter, the smallest only one, and the others were about one and a half. They were

on the south side of the house, and made an angle of 20 or 30 degrees with the horizon. They were stretched and kept tight by wheels for the purpose. Every time the weather changes, these wires make so much noise that it is impossible to continue concerts in the parlour, and the sound sometimes resembles that of a tea-urn when boiling, sometimes that of an harmonica, a distant bell, or an organ. In the opinion of the celebrated chemist. M. Dobereiner, as stated in the Bulletin Technologique, this is an electro-magnetical phenomenon. Do any of our readers know of such an instrument having ever been tried in Britain?

QUERIES. THE best mode of dyeing quills different colours?

By what process, or by what preparation can I effect the removal of stains in marble, called iron-moulds, without cutting or damaging it, so that it shall re-assume its original appearance?

ANSWERS TO QUERIES,

To the Editor of the Chemist. As I can kill two birds with one stone, I beg to inform R. S. F., in answer to his Query in No. XXII., of the best mode of making chemist show colours.

Purple: Solution of nitrate of copper liquor, ammonia and water. Yellow (very beautiful): Cambogia and spirit of wine.

Green: Infus. red cabbage and liq. potass sub. carb.

Blue: Solution of sulphate of copper in nitric acid and compound spirit of ammonia.

Black: Strong infusion of galls with sulphate of iron.

Red: Solution of oxalic acid one part, eight parts of distilled water, with some black ink,

Or, Cochineal and diluted salpt. acid.

.""

SIR, Of all your friends, admirers, correspondents, constant readers, &c. there are none who ought to feel themselves more indebted to you than those who so of ten trespass on your good nature in the character of querists. The ready insertion you give to their productions is a proof of your disposition to oblige, but I cannot help fearing that a continuation of your courtesy in this respect, will be at the expense of your reputation. In No. 17, a very wholesale dealer in interrogatories, yclep't Juvenis, (his age must be his excuse,) wishes to be informed of "The cheapest method of obtaining acetate of tin ;"-" would be glad to see an article on distillation, giving a description of the most approved stills and lutes;"-"wishes to know whether the sun is the primary or secondary source of light; if heat proceeds from the same source and in the same manner;' "what is the best method of obtaining carbonate of ammonia from the ammonia disengaged during the manufacture of coal gas; and the best method of obtaining sulphur from the native sulphuret of iron," &c. Now, is Juvenis quite so young, as to suppose he can obtain any really useful instruction by an answer to any of his queries? I will leave him to judge of the rest by giving him an answer to one. Sulphate of ammonia is first formed by adding sulphuric acid to the gas liquor. The chrystals are mixed with carbonate of lime, heat is applied, decomposition takes place, carbonaté of ammonia is sublimed, and the residuum is sulphate of lime. Juvenis may depend upon this being the cheapest and best method at present known, and the one adopted by the manufacturers of the article at the present time. The next I shall notice is "Alpha," in No. 21, who very modestly wishes to be informed of the best method of preparing nitro-muriatic acid for the dyer's tise, and the cheapest method of setting about the necessary erections for the same? This is one of the articles on which my

very subsistence depends, but so little do I fear a competition with "Alpha," that his wishes shall be gratified. Nitro-muriatic acid is prepared by mixing muriate of soda (common salt) and nitrate of potash (saltpetre) in certain proportions, and, adding sulphuric acid, heat is applied, decomposi tion takes place, nitromuriatic acid is disengaged, and the residuum is sulphate of potash and soda. For the cheapest way of erecting the necessary apparatus, I must refer him to his potter, bricklayer, and iron-founder. Having answered both their questions, I must beg leave to ask Juvenis and Alpha what benefit they will derive from it, and why did they trouble you for information which almost every modern work on chemistry would have afforded them? The fact is, they are quite ignorant of the difference in value between theoretical and practical knowledge. If the former will satisfy them, they have now a proof of its cheapness, in having procured it by merely asking for it: if the latter be required, they will soon find out its superior value, by the trouble and labour it will cost them in its acquisition. So much for your querists: and now, Mr. Editor, allow me to ask, to what clever and ingenious correspondent are we indebted for the long and scientific article in your last week's Number, on the manufacture of borax? You will find, upon inquiry, that the manufacture of borax has been carried on to a considerable extent in this country for many years, and long before the existence of boracic acid in a natural state was known.*

Your obedient servant,

OBSERVATOR.

*Our intelligent Correspondent, we believe, as well as another, who addressed us on the same subject, confounds, in the latter clause of his communication, the purification with the manufacture of the salt. We know that has for a long period been refined in this the crude borax brought from the East country; but we cannot believe that the salt was manufactured before the means of procuring the acid were known.-ED.

Chloride of, muriate

of lime, fixed ammonia.

OXIDE OF, lime. CALCSINTER. A name for the stalactitical carbonate of lime, which is formed by the continual filtration of lime-water through the crevices of caverns.

CALGTUFF. Another species of carbonate of lime, of a soft nature, which is probably deposited by calcareous springs.

CALCULUS, stone. The name given to the stony concretions found in various secretions of animals. Thus there are urinary, biliary, and arthritic calculi. The former are the cause of one of the most painful diseases to which man is subjected. They have been frequently analyzed, and found to consist chiefly of lithic or uric acid. The latter are those which form in the joints of gouty persons, and which are also found to consist principally of lithate of soda.

CALOMEL, chloride of mercury, mild muriate of mercury, submuriate of mercury. A well-known medicine.

CALORIC. The name given to the unknown cause of the sensation of heat in us, and of the expansion of bodies. It is supposed to be a fluid of unappreciable tenuity, endowed with we know not how many properties; but true philosophy rejects all suppositious existences, and confines itself to observing and

recording facts, noting their similarity to one another, and their various relations. By doing this we gradually discover what may be called classes of phenomena, the subordinate parts of which, from their similarity one to another, are arranged together; while, from some dissimilarity, the classes are kept apart. We may, without any impropriety, give a name to the supposed cause of the similarity in the subordinate facts, and of the difference in the classes; but we should always remember that such names are merely verbal helps to memory, and do not, independent of the assistance they thus afford, advance us one step beyond the phenomena we witness. In this point of view, we have no objection to the term caloric standing for the unknown cause of our sensations of heat, the expansion of bodies, and the change in colour which frequently accompanies the expansion, as these effects frequently take place, though not always, simultaneously. There is, however, no resemblance whatever between these effects, and perhaps it is a false philosophy to ascribe to one unknown cause things so very different. If, indeed, at the moment we feel the sensation of heat, there were some one substance always present, which we could at the same time see, grasp, and weigh, there might be some better ground for applying to it the name of caloric; but when this is not the case, we must be cautious not to suppose we have advanced in knowledge by the invention of a term. We say that such inventions explain nothing; and after using the name, and supposing a fluid or a motion, we are just as much at a loss as before in conceiving how this, which itself takes up no space, and which has no sensations, can expand bodies, or excite the pleasureable feeling of heat.

MAGNESIA AND OIL. CALCINED magnesia has the property, if rancid oil be heated with a quantity of it, completely to destroy the rancidity of the oil,