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of experiments upon the decomposition of considerable quantities of ammonia, in which nothing was present but the gas, the metals for conveying, the electricity, and the glass'; and every possible precaution used to prevent error; and in all instances it was found, that there was no loss of weight of the apparatus, nor any deposition of moisture during or after the electrization, but the wires used were uniformly tarnished; and, in one instance in which surfaces of brass were used, a small quantity of olive-coloured matter formed on the metal; but though in this case nearly eight cubical inches of ammonia were decomposed, the weight of the oxidated matter was so minute as to be scarcely sensible. In these experiments the increase of gas was uniformly from 100 to 185, and the hydrogen was to the nitrogen in the average proportions of from 73-74 to 27-26; and assuming the common estimations of the specific gravity of ammonia, of hydrogen, and nitrogen, Mr. Davy's former conclusions are supported by these new experiments: as they were also when the relative specific gravities of these gases were taken with the utmost degree of precision possible, by means of the delicate balance belong ing to the Royal Institution. The specific gravities thus taken are, Nitrogen, 100 cubical inches Hydrogen Ammonia

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29.8 grains

2.27

18.4

The lately-discovered facts in chemis try, says Mr. Davy, concerning the important modifications which bodies may undergo by slight additions or subtractions of new matter, ought to render us cautious in deciding upon the nature of the process of the electrical decomposition of ammonia. It is possible, he adds, that the minute quantity of oxygen which appears to be separated, is not accidental, but a result of the decom position, and if hydrogen and nitrogen be both oxydes of the same base, the possibility of the production of different proportions of water, in different operations, might account for the variations observed: but on the whole, the idea that ammonia is decomposed into hy. drogen and nitrogen alone by electricity, and that the loss of weight is no more than is to be expected in processes of so delicate a kind, is in his opinion, the most defensible view of the subject. But it will be asked, If ammonia be capable of decomposition into nitrogen and hydrogen? What is the nature of the

matter existing in the amalgam of aminonia? and what is the metallic basis of the volatile alkali? These are questions not easily solved; but Mr. D. says, that, in his former communication on the amalgam of aminonia, he stated, that, under all the common circumstances of its production, it seems to preserve a quan. tity of water adhering to it, which may be conceived to be sufficient to oxidate the metal, and to re-produce the am monia. He is even unable to form it from ammonia in a dry state; neither the amalgams of potassium, sodium, or barium, produce it in ammoniacal gas; and when they are heated with muriate of ammonia, unless the salt is moist, there is no metallization of the alkali. The amalgam, which he has reason to be lieve can be made most free from adhering moisture, is that of potassium, mercury, and ainmonium in a solid state: this decomposes very slowly, even in contact with water, and when it has been carefully wiped with bibulous paper, bears a considerable heat without alteration. The ratio between the hydrogen and ammonia produced from the amal gam; is taken as one to two; and if this be accurate, then it will follow, that ainmonia, supposing it to be an oxyde, must contain 48 per cent. of oxygen, which will agree with the relations of the attractions of this alkali for acids to those of other salifiable bases. If hydrogen be a simple body, and nitrogen an oxyde, then on the hypothesis above stated, nitrogen would consist of nearly 48 of oxygen and 34 of base: but if hydrogen and nitrogen are both oxydes of the same metal, then the quantity of oxygen in nitrogen must be less. These views are the most obvious on the antiphlogistic hypothesis of the nature of metallic substances; but if the facts concerning ammonia were reasoned upon, independently of other chemical phenomena, they might be more readily explained on the notion of nitrogen being a base, which became alkaline by combining with one portion of hydrogen, and metallic by combining with a greater proportion.

The solution of the question concerning the quantity of matter added to the mercury in the formation of the amalgam depends on this discussion: for if the phlogistic view of the subject be adopted, the amalgam must be supposed to contain nearly twice as much matter as it is conceived to contain on the hypothesis of deoxygenation, Mr. D. did formerly

rate

rate it at the both part only, but this is the least quantity that can be assumed, the mercury being supposed to give off one-half its volume of ammonia; and he is now inclined to think it may contain theth of new matter on the antiphlogistic theory, and about th on the phlogistic theory. The professor concludes this part of his subject by observing, that though the researches on the decomposition and composition of nitrogen, have produced only negative

results, yet he conceives that they may not be devoid of useful applications. It does not seen improbable that the pas sage of steam over hot manganese, may be applied to the manufacture of nitrous acid: and there is reason to believe that the ignition of charcoal and potash, and their exposure to water, may be advantageously applied to the production of volatile alkali, in countries where fuel is cheap.

(To be concluded in our next.)

MONTHLY RETROSPECT OF THE FINE ARTS. The Use of all New Prints, Communications of Articles of Intelligence, &c. are requested under COVER to the Care of the Publisher.

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A FEW months ago, the writer of the monthly Retrospect in this Magazine, thought it necessary to speak in praise of a plan submitted to the public for improving the art of engraving in England by the Chalcographic Society; and neither the ill-natured remarks of Mr. Landseer thereon, a re-consideration of both pamphlets, his own commendatory article, nor the patronage the scheme has received, induces him to alter his opinion. The circumstances that led to Mr. Landseer's ill-tempered letter on this praise-worthy society, and his illiberal, ungentlemanly, abuse of some of its members, are briefly as follows, and which are here inserted in support of the former observations offered on the published plan of the Chalcographic Society. Mr. Landseer was proposed, at his own request, to be a member of the society, and rejected at the ballot. In the spleen of his disappointment, he published the pamphlet now under consideration. Its object appears, from the title-page, to be fair observations on the plan; but its real objects are the excitement of mistrust and disunion between the members of "the Society for the Encouragement of the Art of Engraving," and those of the "Chalcographic Society;" to thwart the views of the latter by misrepresentation and calumny; and to distract the former in the exercise of their patronage, by a confusion of doubts and scruples.

The letter (for so it is called, although no name is given to whom it is addressed) is a curious specimen of absurdity, spleen, malignity, and, we might say, falsehood; for we in vain look for the "view of improving their scheme of patronage,"

which the title-page promises; and we are
deluded (after purchasing this plan to
improve our stock of knowledge in plan-
ning,) with an intimation, that he has
reserved it for the private inspection of
such gentlemen as may chuse to consult
him. We marvel he did not add, ac-
companied with the fee of a Bank of
England note. If we believe the very
modest Mr. Landseer, it would seem
that all talent, and all wisdom, is centred
in himself, and that no share whatever
belongs to the respectable men who form
the society he opposes; and because they
love quiet and attention to their art, bet-
ter than those disputes and bickerings
that must be the consequence of admit-
ting into their society a man, who was
justly defined, a short time since, by an
artist of high rank and talents, as a "lit-
tle man who is always vexed." It is
truly astonishing and lamentable, that
a man of Mr. Landseer's talents as an
engraver, should desert his burin for
the pen, and enter into unprovoked hos-
tility against his contemporaries. It is
a misfortune even for the public, but a
greater to himself; for its consequences
must recoil upon him. He would do well
to consider that, before he so broadly at-
tacks the characters of others, that his own
is not of that unsullied nature that will
put him out of the reach of retaliation:
let him remember the old Spanish pro-
verb: "That he who has a house of glass,
should not begin to throw stones at his
neighbour's."

Essays of the London Architectural Society
Published by order of the Society. Taylor,

Holborn.

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and improvement of this branch of the Fine Arts. The first essay is by the president, (Joseph Woods, jun. F.L.S.) on modern theories of Taste, and is rather a review of Allison, Burke, Price, and Knight's theories, than an original project. The author combats some, and argues ably on others, of the ingenious, but too fine-drawn, speculations of modern theorists. This essay adds considerably to the general stock on this undefined, and perhaps undefinable, feeling; but it is not so closely applied to architecture, as might have been expected from a professor in the art. The second essay is by Mr. Savage, (vice-president), on Bridge-building, and displays much knowledge of the subject, and sound reasoning. The theories of Dr. Hutton, Mr. Attwood, and the Encyclopædists (in Dr. Rees's edition) are carefully and ably examined, and their defects boldly pointed out, Mr. Savage, as might be expected from a practical architect, (which Dr. Hutton expressly declares his treatise not to be written with the feel ings of) gives examples as well as precept; but, as only part of his essay is printed in this volume, a close investigation of the author's principles must be

deferred till its conclusion. The next and last essay is on Foundations, by Mr. James Elmes, (vice-president), in which this fundamental branch of architective skill, as practised by the greatest architects, is brought to the test of practice, and as boldly condemned where he considers them erroneous. This is a practice that deserves commendation, and should be oftener done; for great names often countenance great errors. Of the inten tion and contents of this highly-useful, essay, Mr. Elmes shall speak for himself in the following quotation. "Having thus quoted the opinions of some archi tects, whose practical and theoretical knowledge have procured them the just distinction of masters in the science, I. shall proceed in the first section of the following essay, (by way of summary,) to collect them to a focus, which I shall denominate the Ancient Practice. In the second, to narrate my own method in common cases, detailing some difficulties that have occurred, with the methods used to overcome them, and the event of their success. And in the third, a compendium of rules drawn from the above sources, which I shall fcall the Modern English Practice of forming Foundations. These investiga-, tions the author has executed with con MONTHLY MAG, No. 206.

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siderable ability; and, as the conclusions are the result of practice, there can be no hesitation in recommending it to the attention of the profession at large. D. The Architectural Antiquities of Great Britain,

displayed in a Series of Engravings, with an bistorical and descriptive Account of each Sub. ject. By John Britton, F.S.A. Part II. No. IV. of Vol. III. Longman and Co. Taylor, and the Author.

This is the fourth Number of the third volume of this very useful work, both to the architect and the antiquary. The plans are architecturally faithful, and the views at once scientific, useful, and picturesque. This Number contains seven engravings, from St. George's Chapel, Windsor, viz. 1. A View of Beauchamp's Monument, &c. 2. Fine Specimens of Groining, &c. 3. Groinings over the organ screen to the Great Western Window. 4 The Great Western Window. 5. Fitzwilliam's Monument. 6. South-west view of the Chapel. 7. In. terior View of the North-aisle: which last is one of the most beautiful specimens of perspective engraving, particularly the distance, which has appeared for a long time, and reflects great credit on Mr. H. Le Keux, the engraver.

INTELLIGENCE.

The Arts have sustained another loss of an able son, and the Royal Academy of a worthy member, in Mr. Zoffanij, who "shuffled off his mortal coil" in the be ginning of last month. Johann Zoffanij, esq. R.A. (sometimes called Sir Johann Zoffanij) portrait and historical painter, was born at Frankfort; and arrived in England to study the arts, about the year 1764, and suffered much from poverty and want of encouragement; from which state he was rescued by lord Barrington, whose portrait he painted. Shortly after this he visited Italy, with recommendations from his Majesty to the grand duke of Tuscany; and while at Florence, he painted his celebrated picture of the Florence Gallery. He afterwards returned to England, which he left for India, where he received much encouragement; and has of late lived in privacy. The style of Zoffanij's works, are truth of expression, a fine deep tone of colour, and high finishing in the detail. His principal works are portraits of dramatic performers of the time of Garrick, King, Shuter, &c.; a picture enbracing portraits of all the members of the Royal Academy; a similar one of the Royal Family, &c. SL

On

On Monday, the 19th ult. Mr. Carlisle commenced his course of anatomical lectures at the Royal Academy, which shall be noticed in our next; as shall be the Rev. Mr. Foster's new Number of his elegant selection from the works of the best masters; and we are glad to see

that he has included Sir Joshua Reynolds among the old masters, who cannot possibly suffer by the connexion.

At the annual meeting of the Royal Academy, on the 5th ult. Mr. G. Arnald, landscape painter, was elected, Associate.

PATENTS LATELY ENROLLED.

MR. MICHAEL SHANNON'S, (BERWICK STREET, LONDON,) for Improvements in the Art of Brewing.

IN

N the specification, giving an account of these improvements, we have outlined drawings exhibiting representations of the machinery, seen on different sides. From the lower part of the copper is a communication, through a cock and pipe, into a box or chamber from which there are five communications, viz, one through a cock to empty it; another to the bottom of the infusing vessel to draw off the contents; another to the top of the infusing vessel; one with a pump, worked by the first mover; and another with the air vessel, which keeps up a constant re-action when required. The infusing vessel may be made of different forms and materials, but it is reconimended, by way of preference, that it should be cylindrical, and of wood, and it is to be provided with two false bottoms, or perforated partitions, one near each extremity, for the purpose of allowing the liquor or wort to pass more freely into and out of the same, during the time of operating. The process is described as follows: Malt is put into the infusing vessel, which in most cases may be filled, or nearly filled, with the same, excepting between the false bottoms or perforated partitions and the end thereof, and the water is to be put in due quantity into the boiler, and heat applied as usual. When the water is suffi ciently hot, it is to be so applied by means of the cocks and pipes above described, that it will rise through the malt to the level in the boiler; but it would not pass through if it were not for the pump, which rs, at the same time, to be worked by any adequate and convenient first-mover, and it draws the water through a lower valve; and, at its returning stroke, forces it through an upper valve, placed within the receptacle on each end of the barrel. By this action the hot water is forced gradually through the mait in a constant stream, the air escaping through a pipe, which returns through the boiler by means

of the cock and pipe, and by this means the wort is kept hot, and repeatedly pas sed through the grain until the strength of the malt is entirely extracted. And whenever it may be found necessary and expedient to cause the water, liquor, or wort, to pass down the infusing vessel instead of upwards, it will then be only necessary that one set of cocks should be shut, and another set opened, and in that situation the heated water will be forced up the pipe, and downwards through the vessel; out of which it will pass into the boiler, by a reverse operation; in this case, it will be needful to keep the cock shut, until the infusing vessel is filled with liquor. By these improvements, the wort may be made as strong as the proportions of materials will allow; the inconvenient and imperfect operation of mashing is avoided, and the sprout, or exhausted grain, may be afterwards drawn out with great facility and saving of labour. A like apparatus may be applied for passing the wort through hops, instead of boiling, in case the same should be preferred, either for purposes of economy, or giving a peculiar strength or difference of flavour to the liquor by this method,

MR. CHARLES WILLIAMS'S,(GRAVEL-LANE,
LONDON,) for a Machine for Grinding
Malt, &c.

The machine, or mill, used on this occasion, is composed of a cylindrical or conical roller, made of cast-iron, or any other metal, with grooves cut in it in an oblique or parallel direction: this roller acts against loose knives, made of hardened steel, and screwed together so as to form the same curve as the roller. These loose knives, or cutters, may be taken out and ground, or sharpened, at pleasure. In the margin of Mr. Williams's specification, is a drawing of the elevation of the mill. The roller is put in motion by a steam-engine, or any other power; which roller acts against the knives or cutters, fixed in a parallel di

rection

rection with the roller. The malt, or other substance, to be ground, passes between the rollers and the cutters. There is an adjusting screw to keep the roller at a proper distance from the knives. There are two levers that act against the brasses of the bearing of the roller, and keep the roller up to its work. A farther use of these levers, is to admit and allow the roller to rise up, when any thing gets between it and the knives, that by its hardness might injure the one or the other, and let it pass through; the roller will then fall into its former station. There are weights made to slide on the levers, so that they may be adjusted, and more weight not permitted to act against the roller than is sufficient to keep it to its work. The roller and cutters are worked upon a carriage, which carriage may be made of divers forms. Besides the figure already described, there are others exhibiting the spindle, to which the moving-power is to be applied; the sliding brasses for the roller to work in; the double-wired screen, to take the rubbish and dust from the malt, or other matter. The upper wire is coarse enough to let the malt, or other matter, through, and the bottom one to take out the dust. There is a beater fixed on the screen to act against projections on the roller, to give motion to the screen to shake the malt, or other matter: there is also a spout to clear the top screen of the rubbish, and a hopper fixed at the top of the screen, in which is put a wire to take out the thickest of the rubbish.

MR. STEPHEN HOOPER'S, (WALWORTH,) for a Thermometer for ascertaining the Heat of Bakers' Ovens,and various other purposes.

The principle of this instrument consists in the comparative degree of expansion, or contraction, which takes place in different substances, when these substances are exposed to different degrees of temperature; and, in order to reduce this to practice, the instrument is constructed as follows, which we shall give in the patentee's own words: “I make use of two rods, bars, or tubes, of any convenient length and shape; and the sub stances of which these rods are made are such, that one of them is subject to a greater degree of expansion or contrac. tion than the other, when exposed to different degrees of temperature; or, in other words, I chuse such substances, that one

of them may be subject to as little, and the other as much, variation in length as possible, when heated or cooled; possessing at the same time such other properties as render them of convenient appli cation. I do, therefore, generally make use of brass and wooden rods, or, as being more convenient, a brass tube and wooden rod, which are hereinafter more particularly described as follows: that is to say, I make a brass tube of any con. venient length and diameter. The length of the said tube I generally make equal to the length of the oven to which the thermometer is intended to be applied, and about an inch and a quarter in diameter. Into the said brass tube I introduce a wooden rod, made of fir, or any other very straigh -grained wood; the wooden rod being nearly of the same length as the brass tube, and of such a diameter as to slide freely backward and forward in the brass tube without sticking. The said brass tube and wooden rod, are firmly fixed to each other at one end, so that if any expansion or contraction arising from a change of tempera. ture, takes place in the brass tube, that change of temperature will be indicated at the other end by the increase or decrease of the length of the brass tube, when compared with that of the wooden rod, the said rod having a scale fixed thereon for that purpose. But as the divisions upon the said scale, when so contracted, are too minute to be easily made, or distinctly observed, I prefer a scale with larger divisions, which I obtain by applying a lever, or a combination of levers, according to the wellknown methods now in use for construc ting pyrometers, or by a rack and pinion; in which case I affix a rack to the end of the brass tube, and cause the said rack to turn a small pinion; and upon the axis of the said pinion I place a hand, or index, which points the degree of expansion or heat upon a circular plate, properly divided. The said pinion and plate, in which the axis of the pinion turns, are affixed to the wooden tod.”

Mr. Hooper next describes the mode of using his thermometer, when applied to bakers' ovens: that is, he causes a channel, or hole, to be made in the brickwork, about six inches below, and parallel with the bottom of the oven, extending from the mouth to the farther side of it, in such a direction as that a vertical plane passing through the channel, would nearly bisect the oven door. The instru

ment

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