charge of this mixture is introduced to the charging-chamber or channel, with the partition, d, in the position represented. The cover is then replaced, in order to prevent the escape of gases, when the partition is withdrawn, to allow the charge to descend into the furnace, which falls upon a body of incandescent fuel, which should be at a certain height from the twyer-hole. A charge of fuel is next introduced, and afterwards another charge of the ore, these charges being repeated in succession until the furnace is sufficiently filled. In the same manner, the furnace is to be replenished from time to time as the entire charge sinks below the proper depth. By the excessive heat of the furnace, the zinc becomes volatilized and carried into the condenser, f, while the scoria falls to the lower part of the furnace and flows from the aperture, i,i,i. The gases arising from combustion of the fuel pass off with the volatilized zinc, which separates in the condenser, f, the gases escaping by the openings, k, in each side of the condensing-chamber; but as they are liable to pass off with particles of zinc in suspension, they are passed through an hydraulic main, and afterwards allowed to escape into the atmosphere. Thus all solid matters are retained, and the zinc, with other matters deposited in the condenser, f, may be withdrawn at the openings, 7. If the ore has been previously comminuted, it is preferable to make it into a sort of paste, by mixing the flux with a sufficient quantity of water for the purpose; this will have the effect of producing the layers more regular, and prevent the ore dropping through the fire. In many instances, zinc ore is found mixed with sulphuret of lead, which, according to this mode of operating, will be obtained by fusion, therefore running through the fire and out at the lowest opening, i, while the zinc, at the same time, will be volatilised, as before described. The second part of this invention is carried out as follows:-The zinc to be operated upon is placed in what he terms "subliming-pots," or retorts; a series of these are arranged in a furnace, on the sole of which they are supported by a prop from the bottom of the retort, which is hemispherical. The lip or flanged edges are on the same level, and are surrounded by a suitable partition, which divides the body of the retort (which is in the furnace) from the space into which the retorts open, they being covered on the top. The covers have a number of small perforations, through which the vapours of the zinc pass, as the metal

becomes volatilized; these vapours are all collected in a chamber or passage above the retorts, and conveyed into the oxidizing chamber, a current being created thence by the draught of a chimney. The oxidizing-chamber has several partitions placed transverse to the course of the gases, causing them to pass over and under, thereby aiding the deposit of the metallic oxide, the last partition through which they pass (being made of wiregauze) preventing the passage of the oxide up the chimney. The flues from the furnace are conducted over the collecting-chamber or passage, in order to maintain the heat necessary for burning the vapours arising from the retorts. The sole or base of the furnace, on which the retorts rest, is separated from the fire by a ridge, and is so inclined, that, in the event of rupture to any of the retorts, the metal is collected by a suitable channel, and is conveyed to a suitable receiver on the outside of the furnace. Having completed the description, he observes that he is aware that oxide of zinc has hitherto been obtained by distillation, and causing the metal, when volatilized, to come in contact with atmospheric oxygen in an oxidizing-chamber; he, therefore, does not claim generally producing the oxide of zinc in this manner, neither does he confine himself rigidly to the precise arrangements shown, as he considers that they may be considerably varied without departing from his invention; but what he claims is, the obtaining of metallic zinc by means of the apparatus, and in the manner hereinbefore set forth, or by any modification thereof. Secondly, the producing oxide of zinc by the distillation of metal, or matters containing the metal, in retorts or subliming-pots or other vessels, furnished with perforated covers, through which the volatilized metal may issue, and are conveyed into an oxidizing-chamber, where it is met or brought into contact with the oxygen of the atmosphere, and becomes converted into oxide of zinc.

THE ARIEL STEAM-VESSEL fitting with smoke-consuming apparatus by Mr. Haig, is nearly ready for trial. The inventor appears to have made a great improvement in his mode of attaining an object so desirable on board steam-vessels, and the whole of the new works are under deck instead of above, as in the first trial. The result is anxiously looked for, as, in the event of the plan being thoroughly successful, steam-vessels consuming their smoke will be of great importance even during peace, when engaged in the pursuit of slave-vessels.

THE NEWARK PRIZE COTTAGE GRATE.

Registered for MR. W. N. NICHOLSON, of Newark-on-Trent. Dated July 12.-No. 1495.

The annexed engraving represents a design for a grate or range, the novelty of which consists in the back and sides of the fireplace being formed of fire-clay, the back being of the peculiar figure shown in the section; the lower angle extends to the front bar of the range; thus a bottom grate is dispensed with. The fire range is made with vertical, instead of horizontal, bars, of such a shape as to obstruct as small a portion of heat as possible; the fall-bar is also made to fall either over the fire, or the hearth; by simply lifting the range (which slides in grooves), the remains of the fire are readily and effectually cleansed out without the trouble of poking. The door of the oven is so constructed as to form, when open, a convenient hot-shelf. The

advantages arising from the arrangement of the fire-clay back and sides are very considerable, as every portion of heat from the fire is rendered available; thus a much greater heat is radiated than from grates of the ordinary construction, whilst every particle of the fuel is consumed; and when not in active use, combustion is carried on more slowly. Lastly, though by no means least, the cost of this grate is exceedingly moderate; the inventor depending upon a very extensive sale will supply them at a price not higher than those of the commonest kind. The Royal Agricultural Society, at the York meeting, 1848, awarded their premium to Mr. Nicholson, for his new Newark Cottage Range, as being the best out of thirty-two articles of the kind put in competition.

springs at the side, in the event of the net-work cover and the other bow being thrown up, which is otherwise held in its position by the spring-catch at the end of the cot. Protection has been obtained for parts forming the hood and cover, the itself being old and before used.

LETTERS PATENT.

THE following paragraph has been going the round of the newspapers, and as it is likely to create a wrong impression in the mind of the public, we are induced to call attention to its inaccuracy:

"LETTERS PATENT.-A Parliamentary paper recently published shows that the total number of letters patent for inventions granted in the United Kingdom in 1847 amounted to 740, against 761 in 1846, and the total fees received thereon to £32,977, against £34,108 in the preceding year. Of this sum, £20,518 was paid over to the Consolidated Fund, and £9,830 to the several offices entitled to receive the same."

Now, by dividing £32,977 by 740, it would appear that the cost of a patent is £44 12s. and a fraction. We heartily wish that this was the fact. ROBERT HOUDIN, with all his conjuring, could not squeeze a patent from the officials at double that sum. A few little items are left out of this veracious Parliamentary return. In the first place, nothing is said about the item of £41 2s. for stamps, or of £13 AttorneyGeneral's fees, which, when added together with one or two more sundries, will make the change out of £100 appear very insignificant. The return is made from two offices only, and does not include the items above named, for the reason that the stamps, &c., go to quite a different branch of the revenue; the stamps, of course, to Somerset House, to swell the £7,000,000 derived from that source of the public income. The £20,000 paid to the Consolidated Fund ought not to be wrung from the pockets of Inventors, and then the stamps, which benefit the public, might

be paid without murmur. Let not the public think that Patent agents, whose charges are reduced to the minimum scale, can procure patents for £44. They are quite welcome to the change out of £100, and to the trouble to boot. A Parliamentary return of the disposal of the whole fees would be useful, but this would " a tale unfold."

SIR WILLIAM BURNETT'S PATENT SOLUTION.

We have received a letter from Mr. Jackson, the Secretary to the Company for Sir William Burnett's Patent Solution for the preservation of timber from fire, respecting a letter from a railway shareholder, in which the writer calls the attention of the Railway Directors to the recent fires on the various lines of railway, and recommends the use of Burnett's Patent Disinfecting Fluid, whereas it should be Burnett's Patent Solution; and, again, the writer says: "It may be a little more expensive than coal tar" whereas, Mr. Jackson states the solution from coal tar is a good deal more expensive than that produced by Sir William Burnett's patent.

It is a positive fact that, throughout Great Britain and Ireland, a quantity of flour sufficient for the supply of many thousands is every day destroyed, dissipated, and utterly lost to human use.. This is the inevitable result of using yeast in the composition of bread. A portion of flour becomes decomposed in the process of fermentation, and passes off into the atmosphere in the shape of carbonic acid. As it escapes, it puffs up the tenacious dough, and makes it spongy light. This is the only end for which yeast is employed in bread-making; but the same object can be effected quite as well by other chemical processes, which do not occasion any loss of substance to the flour. Dr. Dundas Thompson has ascertained, by experiments on a large scale, that in a sack of flour there is a difference in favour of bread made without yeast, to the amount of 13lbs. 13oz.; or, in round numbers, a sack of flour would produce 107 loaves of unfermented bread, and only 100 loaves of fermented bread of the same weight. Hence it appears that in the sack of flour, by the common process of baking, seven loaves,. or six and a half per cent. of the flour, are driven into the air and lost.-Economist.

INSTITUTION OF MECHANICAL

ENGINEERS.

The quarterly meeting of the members of this society was held in the rooms of the Philosophical Institution, Birmingham, on Wednesday, the 26th July. The attendance was large and highly respectable.-G. Stephenson, Esq., presided; and amongst the members present were-The Mayor, C. Geach, Esq., Messrs. Alderman Beale, M'Connell, Cowper (King's College), Buckle, Slate, Henderson, Fothergill, Miller (Blackwall), A. E. Cowper, Jones,

Wright (Saltley), Marshall, Walker, Smith, B. Gibbons, De Bergue, A. Smith, Ramsbottom, Robertson, Cliffe, &c. The first business brought before the meeting was the President's paper

ON THE FALLACIES OF THE ROTARY ENGINE.

Before entering on the consideration of the subject, the President invited Mr. Onions, who is not a member of the Institution, to describe a disc engine, of which he is the inventor, and to state wherein it differed from other rotary engines. He claimed for his engine a superiority over the crank principle in power and saving of fuel; the chief peculiarity, however, being an improvement in the mode of packing, so (as was alleged) as to make its parts perfectly tight. Mr. Onions asserted, that the loss of power in the use of the crank was estimated by some eminent men at ths. This, he stated, was saved by his engine. There was no friction, and yet by this mode of packing all leakage was obviated. After a few remarks, condemnatory of the principle, the President proceeded to read his paper on this subject. As the explanations were accompanied by references to diagrams, we adopt so much of the paper as will give an idea of Mr. Stephenson's argument. He remarked that, as all levers gave out their power at right angles to their fulcrums, it would be seen that a right angle line from the connecting-rod to the centre of the beam would be the true measure of the length of the beam when the crank was at half-stroke, therefore the th of half the length of the beam would be gained by the piston end of the beam. The crank being 3 ft. long, the up and down stroke of the piston would be 12 ft.; the crank-pin would, of course, have passed through a space of nearly 19 ft. Now, a weight hanging upon a drum nearly 4 ft. diameter, would balance the same weight on the piston end of the beam; each would moveat the same velocity, and pass through the same space in the same time. It would

be observed, that from C to D on the diagram was a little more than one-third longer than from G to D; it would, therefore, be seen that the weight at the piston end of the beam had a little more than one-third advantage over the weight of the drum. And it would also be seen that from C to E was half-way from halfstroke to the bottom centre; at this portion of the stroke, the leverage of the crank would be nearly two feet. The increased power that existed in the crank from half-stroke to this point would gradually be lost from D to H; it was, therefore, clearly proved that no power was lost by the crank motion, as the weights resolved themselves into a simple lever. There would be a little loss of power when the engine was turning the centres, which is compensated for at the connecting-rod end of the beam by the segment of the right angle line. Now, a rotary engine could only give out its power on the arm, like any other lever; and if the piston passed through a space of 19 ft., it would just balance a weight equal to the same power pressing through the same space. The President, in continuation, said that no man could improve the lever it was useless to talk at that time of day of the loss of power by the crank; there was no such loss. He asked, what had been the performance of Mr. Onions' engine at Derby, where it was tried.

Mr. Onions said, that in those experiments the saving was equivalent to 20 per cent. Would the President believe the fact if he saw it ?-The President, with good-humoured warmth, exclaimed, "No, I wouldn't, Sir. I would believe I were mad first, or that there was magic in the experiment."

Mr. Miller, of Blackwall, remarked that there was no loss of power by the crank; and he might also add, that nobody, he believed, objected to the principle of the rotary engine, except so far as regarded the difficulty, or rather the impossibility, of packing it perfectly tight. No doubt the rotary engine had its advantages, such as its application to the screw in marine engineering, and wherever small space and considerable power were necessary; but the rock upon which inventors split, was the packing. He would as soon think of inventing perpetual motion as of overcoming that difficulty.

After some remarks from Mr. Robertson, of Plymouth Dockyard, and a humourous illustration by the President, of the power of Beale's engine, and that of Lord Dundonald-the former of which kept