stove, the warm air from which will quickly thaw the water-pipe, &c. Yours, &c.

FRANCIS JACKSON.

IMPROVEMENT OF CANAL NAVIGATION.

GENTLEMEN; I some months since devised a plan for impelling barges on canals by steam; and not being provided with the pecuniary means to render this improvement available to my personal advantage, I beg leave to offer it for your very useful publication.

I propose that one wheel should be affixed to the stern of the barge, protruding a sufficient length to be clear of the rudder, and extending the whole breadth of the vessel's stern; this wheel to be worked by one engine, fixed towards the after-part of the vessel.

Since I first sketched a plan of this improvement, I have read in the papers of some person having applied something similar to a passage-vessel; but I shall not fear any imputation of having borrowed my method from that person, because I could, if it were necessary, bring forward respectable persons who have seen mine long since: this, however, is of little consequence; my present object is to draw the attention of the public to the possibility of doing away with the present mode of canal navigation by horses, which is both slow and expensive: should mine be brought into practice, I presume it would be found that a barge might be sent with forty tons of goods from London to Liverpool in sixty hours, at an expense of about 10%.

Such of your readers as are inclined to try an experiment, may obtain further elucidation from, Gentlemen, Your humble servant, R. J. M.

ANSWERS TO INQUIRIES.

No. 42.PURIFYING GOLD.

2, Charlotte-street, Sadlers' Wells. GENTLEMEN;-The following information is, I apprehend, that which your correspondent" Niloe Esor" is inquiring for, and which I have delayed sending

till now, in the hope that some one more competent than myself would have supplied it. To render this as intelligible as possible, I shall describe how I should act with a quantity of common gold of different values. I should first melt the pieces together, and cast them into one ingot, from which I should obtain a part. ing assay; that would show what amount of fine gold and fine silver is contained in a pound troy of the ingot; then reduce the ingot, by flatting, to the thickness of strong writing paper, anneal it, for the purpose of making it clean, cut it in pieces about half an inch square, introduce the pieces into a straightnecked retort, pour a sufficient quantity of aqua-fortis, slightly diluted with water, into the retort, to cover the metal (stopping the mouth of the retort partially, with twisted paper, to prevent the too free escape of the evaporation), place a basin, half-full of dry sand, over a slow charcoal fire, put the retort into it, and there let it remain until the metal is completely dissolved, adding more aquafortis, if necessary, to keep up the effervescence. I would then fill the retort with warm water, which must be gently poured off into a glazed earthen vessel, leaving the sediment at the bottom of the retort; this must be repeated, perhaps twenty times, until the water come off quite colourless. The precipitate matter must then be carefully washed out of the retort into a snooth basin with a lip, as much of the water poured off as possible, and the sediment removed into a crucible; should any of the sediment remain in the basin, it may be soaked up with a small piece of linen rag, which may be put in the crucible; when almost dry (which may be expedited by placing the crucible on or near a slow fire), as much pounded pearl-ash as will cover the sediment, and about half an inch in depth, must be placed in the crucible, which must then be subjected to a gradually increasing heat in a blast furnace, until the precipitate be completely fused, when it may be cast into an ingot, or allowed to cool in the pot, which is the method I generally adopt. As in all the gold worked by jewellers there is some portion of silver, I never wash the precipitate very closely, preferring rather to retain some of the silver, than run any risk of washing away the gold; but care and practice will produce it pure.

The silver which is held in solution in the water is next to be obtained. The glazed earthen vessel which contains all

the washings, should be a large pan, with a small round hole, about two inches from the inside bottom, which, till wanted, can be plugged up with a wooden peg. Into the solution throw a red-hot plate of copper, about the sixteenth of an inch thick, and at least half the size of the bottom of the pan; let it remain undisturbed for two days, at the end of which, drop two or three grains of common salt into the liquid; and if there is no appearance of cloudiness in the water they pass through, the silver is all precipitated. The water must then be drawn off at the little hole, giving the opposite side of the pan a gentle elevation to clear off as much of the water as possible; then plug up the hole again, fill the pan with clean water, and wash the silver off the plate of copper; removing which, rab the precipitate well between your hands in the water, to separate it from the acid, which may still cling to it; leave it to settle, which it will soon do; then pour off the water, and proceed as with the gold precipitate. The copper may then be obtained by the introduction of an iron-plate; but from the smallness of its value, I have never been tempted so to do, except for the sake of the experiment.

The information given by your correspondent "Rose Colin," though strictly true, is not, I imagine, that which Niloc Esor seeks for. The mode I have pointed out has, I believe, been in use for centuries; but that there may be a better, or that there may be an improvement on this, I have little doubt; and I hope that those acquainted with either, will promote the cause of Science, by giving to its votaries all the advantages in their power through the same medium. I am, Gentlemen,

Your obedient servant,
G. STACEY.

No. 44.-TEMPERING IRON. GENTLEMEN ;-In reply to the query of your correspondent Z. Y., as to the inequality of the temper of iron, I beg to say, that the mode he has adopted of making new iron from old scraps, sunk in a charcoal finery, is quite at variance with the possibility of obtaining his object of procuring soft or regular iron.

Let him select good gray pig-iron, equal and regular in quality, and refine it; then work it under the hammer into a bloom or billet, and if proper care be taken, it will give him a regular good and soft iron, fit for most

purposes to which charcoal iron is ap plicable; if, however, it is wanted for some very particular purpose, where any admixture of tongh with bright iron would be objectionable, let him stamp his charcoal lump under the hammer 10 half an inch in thickness, and immediately emerge it into a bosh or cistern of cold water; and afterwards ribble, or break it under the hammer cold. When broken with a sledge hammer into small pieces, the bright and tough may easily be selected, and worked separate into blooms, and rolled. This will give your correspondent all he wishes.

No. 46.-FLAVOUR OF BRANDY. GENTLEMEN ;-In answer to the inquiry of your correspondent in your 48th Number, as to what is used to give the flavour to brandy, if he means the best brandy of France, which is Cogniac brandy, I must tell him that no artificial flavour is requisite, as the brandy has all the delicate, pure, delicious flavour on coming from the still. As a proof of this, I would recommend him to taste it in this state, which he may do at any of the principal importers of brandy, where he will find it with no other colouring matter but what is extracted from the wood of the cask, and in which state it is drunk in Paris, and in other parts of France. John Bull, however, must have his humour, and therefore it is coloured for him with nothing worse than burnt but if the inquirer wishes to know sugar; what is used to flavour that abominable compound called British brandy, "I could a tale unfold," but that I have a high respect for certain individuals, called distillers, chemists, and others whom such an exposure might injure; but, as Hamlet says,

"They do but jest, poison in jest;
No offence i' the world."
I am, gentlemen,
Your obedient servant,
BIBO.

INQUIRIES.

No. 53.-CLEANING MARBLE. How can the polish of marble tables, when water, tea. &c. has been spilt on them, be restored?

No. 54.-BORING FOR WATER. Will the system of boring for water answer in the neighbourhood of chalk hills?

No. 55.-COAL-MINE QUERY.

Cadoxton, Juxta Neath, GENTLEMEN-I beg leave, through the medium of your valuable work, to propose the following question, not doubting but its discussion will develop much useful information to many persons interested in coal properties.

There shall be two veins of coal, one nine feet thick, and the other four feet thick, whose local situations are exactly similar, both having good roofs or tops, each vein lying under twenty acres of land. I require to know what quantity of coal can be worked from each separate vein, and which of the two veins can be worked with the greatest profit, both to the lessor and the lessee, both paying the same royalty, and admitting each cubic yard to weigh 100 lbs.

A YOUNG COLLIER.

NEW PATENTS.

To William Harrington, of Crosshaven, in the county of Cork, esquire, for his improved raft for transporting timber.15th June-6 months.

To Charles Chubb, of Portsea, Hampshire, ironmonger, for his improvements in the construction of locks.-15th June -2 months.

To Benjamin Ager Day, of Birmingham, Warwickshire, fire-screen maker, for certain improvements in the manufac turing of drawer, door, and lock knobs, and knobs of every description.-15th June-2 months.

To John McCurdy, of New York, United States of America, but now of Snow-hill, London, esquire, who, in consequence of a communication made to him by a certain foreigner résiding abroad, is in possession of an improved nethod of generating steam.-15th June -6 months.

To Philip Taylor, of the City-road, Middlesex, engineer, for certain improvements in apparatus for producing gas from various substances.-15th June -6 months.

TO CORRESPONDENTS.

T. M. B.-W. G.-J. E.-and P. Y. on the London Mechanic's Institution, have been received; but we must defer the subject for a week. We shall only say at present that we have "insinuated"

nothing that we are not fully prepared to substantiate when the proper occasion arrives.

We beg to refer Quivox, who wishes to know which of the Committee of Managers go out of office in September next, to the 72nd of the Rules and Orders, where he will find it provided that "The thirty committee-men shall also be elected for one year, and no longer, with the exception of those for the first year, of whom the last fifteen on the list shall go out of office on the first Tuesday of September, 1824, and be replaced by fifteen new committeeinea to be then elected for the year ensuing." The last fifteen on the list are, of course, the fifteen who had the smallest Lumber of votes, a statement of which will be found in our 17th Number, page 264.

T. G.'s paper has been forwarded as directed, not that we pronounce it " unworthy of insertion," but that we may abridge, as far as possible, the controversy to which it would lead.

T. M. B. will accept our best thanks for the sample of the instrument which he has so obligingly transmitted to us. It shall be left as directed, as soon as a drawing of it is made.

Communications received from D. to Quodlibet-Troublesome Tony-Nagthorn Copcake-The Corn-flour and Bread Company-W. II. D-Scribotinto -A Constant Reader-A Seaman-G. Thurnell North Star (whose duplicate of the same communication never came to hand)-E.-Bisinnth-W. D.-PhiloLiverpool-Dr. Gilchrist―R. Cartwright -A. B.-Mary-Domine-John Square -F.-Q. in the Corner Johnson Ses miquaver-Dr. Smith Preceptor-Previous Question, ... sao ?

ERRATA.

In the paper of Mr. Pasley, p. 334. last sentence, for those employed in proving gun-barrels, read browning gunbarrels.;

P. 299, col. 2, line 16 from top, for 148 inches, read 158.

Communications (post paid) to be an dressed to the Editors, at

THE PUBLISHERS, KNIGHT AND LACEY, 55, Paternoster-Row, London.

T. C. Hansard, Pater noster-row Press.

Descriptive History of the SteamEngine, by ROBERT STUART, Esq. Civil Engineer. 1 vol. 8vo. Illus trated by Engravings of Fortyseven Engines. Price 8s.

We have much pleasure in bringing under the notice of our readers the volume before us. It is at once the best and the cheapest account of the steam-engine that has yet appeared. Hitherto the facts of its history have lain so widely scattered, or when partially collected, have been retailed at so great an expense, that they have remained quite beyond the reach of those classes who, from being engaged in the construction of machinery, and in directing its operations when applied to manufactures, have naturally a greater interest in a knowledge of such facts, and by knowing them must be more likely to introduce and promote new improvements than any other body of men whatever.

Mr. Stuart remarks, with great truth, that all that has been done by merely learned men, in the application of steam as a moving power, is of no practical "mark or likelihood." Twenty years ago, Hornblower ɔbserved that "the most vulgar stoker may turn up his nose at the acutest mathematician in the world, for (in the action and construction of steamengines) there are cases in which the higher powers of the human mind must bend to mere mechanical instinct;" and the observation applies with greater force now than it did then. We know not, therefore, how the remark has originated, or what "philosopher" first claimed, for theoretic men, any part of the honour of being instrumental, even indirectly, in the perfecting of the steam-engine; or who gave currency to the phrase of its "invention being one of the noblest gifts that Science ever made to mankind." The fact is, that science, or scientifio men, never had any thing to do in the matter. It was a toy in the hands of all the philosophers who preceded Savery, and it again must become a toy before the speculations of Bossut, the ablest and atest of the philosophers who have

written on the subject,, can be made to bear upon it. Indeed there is no machine or mechanism in which the. little that theorists have done, is more useless. The honour of bringing it to its present state of perfection, therefore, belongs to a different and more useful class. It arose, was improved, and perfected by working mechanics, and by them only; for tradition has preserved to us, the fact of Savery having begun life as a working miner;-Newcomen was a blacksmith, and his partner, Cawley, was a glazier;-Don Ricardo (Mr. Richard) Trevithick, was also an operative mechanic ;-and so was the illustrious Watt, when he began and after he had made his grand improvements."

Mr. Stuart commences his history with an account of Hero, of Alexandria's engine, which is nearly similar to that given of it in our 25th, 26th, and 27th Numbers. "No other notice," he says, "of steam as a first mover occurs in the works of ancient authors, nor in modern writers, until about the year 1563." So it has been customary to state; but we can mention one modern instance, at least of a date more than five humdred years older, where it is distinctly recorded to have been applied to machinery. In Malmesbury's History we meet, under the date of 1002, with the following paragraph: "In the church of Rheims are still extant, as proofs of the knowledge of Gerbert, a public professor in the schools, a clock constructed upon mechanical principles, and an hydraulic organ, in which the air escaping in a surprising manner, by the force of heated water, fills the cavity of the instrument, and the brazen pipes emit modulated tones, through the multifarious apertures." This we incline to think was the earliest modern application of steam; and we are rather surprised that it should have been so long overlooked.

In 1563, one Mathesius hinted at the possibility of constructing an apparatus similar in its operation and properties to those of the modern steam-engine. About thirty years after that period, a Whirling Oclipile