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ligneous acid, or to distilled vinegar until no more is dissolved. If nitrate of ammonia be employed, the proportions must be eighty parts of the crystals to fifty parts of carbonate of lime. Of course, in every case, the amount of water evaporated in a given time must be taken into account, as in proportion to the water evaporated will be the carbonate of lime set free, and the quantity of the ammoniacal salt required. The action of the muriate of ammonia (which for the reason before given I prefer) is partly chemical and partly mechanical. First, it is chemical, inasmuch as after the introduction of the salt into the water a double decomposition takes place. The muriatic acid combines by elective affinity with the lime to form muriate of lime, while the carbonic acid passes to the ammonia, and forms carbonate of ammonia; the former, or the muriate of lime, remaining in a state of solution, and the latter, or the carbonate of ammonia, volatilizing under the influence of the heat, and passing off along with the steam.

This decomposition, however, goes on slowly and gradually. When the salt is added in considerable quantities at a time, it remains, in part in a state of a muriate of ammonia, until fresh supplies of water, containing additional quantities of carbonate of lime to be decomposed, are introduced. In practice, therefore, it will be found of great advantage so to use the muriate of ammonia, that is, to add it to the water in considerable quantities at a time, since, in this way, one application may suffice for several days or even weeks; this, however, will depend on the quantity of carbonate of lime in the water and the rate of evaporation. The mechanical action of the salt (as also of the acetate or nitrate, or other salts of ammonia, as before stated) consists in its increasing the density of the water, (without, however, affecting its clearness,) and thus assisting to retain in a state of suspension any foreign matter, which would otherwise sink to the bottom, and there form a solid incrustation."

MESSRS. NASMYTH AND MAY, for improvements in working atmospheric railways, and in machinery for constructing Patent the apparatus employed therein. dated, October 22, 1844; Specification enrolled, April 22, 1845.

It is universally understood, that in working atmospheric railways on the present principle, the requisite vacuum is obtained by the combined action of steam-engines and air-pumps, which, on a scale of sufficient magnitude to be useful, is found to be so expensive as to amount to almost a prohibition. The present invention has for its object to diminish the expense, and to in

crease the efficiency and rapidity of the process, by entirely superseding the use of both the engines and air-pumps.

With regard to the first part of the invention, it will be found, that, owing to the peculiar character of the apparatus, and the mode of working it, a greater effect or extent of vacuum can be instantaneously obtained in the traction tube, and a certainty of more quickly closing the longitudinal valve, so as to prevent leakage consequent on any want of power in the exterior atmosphere, from the partial state of vacuum in the traction pipe; and this apparatus may also be used to assist the air-pumps, in order to obtain a sufficient withdrawal of the air at starting, the exhaustion being afterwards continued in the usual way by the working of the air-pumps alone.

The arrangement of this apparatus in its general features, consists of two tall upright air-tight vessels, and of a third vessel also air-tight, which three vessels considered conjointly constitute a set, so that in extending the power of the apparatus, the same set of three vessels may be repeated any number of times, or the size of the vessels may be increased for the same purpose.

In order to describe the action of this apparatus, and the manner in which the vacuum is produced, we shall suppose that steam is introduced from a suitable boiler by means of pipes, so as to enter into the three vessels above named; as the steam enters at the top, it will, in consequence of its less specific gravity, occupy the upper parts of the vessels, and as it continues to flow in, it will depress and force out the air through valves or orifices placed in lower situations for that purpose.* As soon as this is accomplished, the further influx of steam is for the instant arrested, and a valve is opened, which admits a stream of cold water from a cistern placed at a convenient

*It is an admitted fact, which has been verified by numerous experiments, that if low-pressure steam, whose elastic force is a little in excess of the atmosphere, be equally and uniformly admitted at the top of a vessel full of air, so far from the steam penetrating and mixing with the air as might naturally be expected, there is instantly formed between the surfaces of the steam and air, a stratum of separation somewhat similar to a solid disc, in consequence of which, the steam by continuing to flow in, as effectually expels the air from the vessel through orifices in the lower parts as if it were acted on by a solid steam tight piston; and it is this circumstance which has enabled Messrs. NASMYTH and MAY to avail themselves of the very simple and efficient method of obtaining a vacuum, which constitutes the subject of their present patent. There can, however, be no doubt that some of the steam will be condensed, by coming in 'contact with the air in the vessel, but the effect produced in this way is so very small as scarcely to be worthy of notice.-ED, M. M.

height, to flow into the third of the abovenamed vessels forming a condenser, and this jet of cold water, not only instantly condenses all the steam in the condenser itself, but also that in the second of the other vessels, thus producing a vacuum in the second vessel, while the first continues filled with steam. The moment this takes place, a valve is opened to the traction or vacuum tube, and a portion of the air contained in it, is abstracted through the opening into the vessel where the vacuum was formed; the valve is then closed, and a free communication is opened between the vessel thus filled with rarefied air and that containing steam, and the steam being of greater pressure than the rarefied air, a portion of it will flow from the one vessel into the other, until an equilibrium is established between the vessels. The communication is then cut off, and the remaining steam condensed as before, by opening a communication between the condenser and the vessel which contains it; a valve is immediately opened to the traction-pipe and a further portion of air is drawn in through the opening, thus filling the vessel which was rendered vacuous by the condensation of the steam formerly contained in it. A communication is now opened between the boiler and the other vessel which already contains a small portion of steam, and also rarefied air admitted by the first operation; this further supply of steam expels the air into the atmosphere, while the same process is being renewed with respect to the other vessel. Thus, by expelling the air from one vessel, while it is being abstracted from the traction tube by the other, a continuous exhaustion is kept up, and by maintaining a constant supply of steam with a regular process of condensation, the vacuum is obtained with very great rapidity.

Our readers, of course, will be aware that, in order to obtain the greatest advantage from the apparatus, it must be rendered self-acting. Now the patentees have given a full description of their method of effecting this purpose, which is exceedingly ingenious; but since it forms no part of their patented claim, we do not think it necessary to follow them in detail; and the more especially so, as the various methods by which similar objects are obtained are sufficiently understood. We shall therefore now proceed to describe the second part of the invention, which consists in applying the pressure of the atmosphere to the movement of a piston, acting on the brakes of carriages, in order to arrest their progress on atmospheric railways; and this is accomplished in the following manner :

Upon the carriage, or some part of the

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framing, there is placed an air-tight vessel, capable, when exhausted, of sustaining the pressure of the atmosphere. This vessel is exhausted, either by a tube connected with the traction tube, or by a small air-pump, worked by an eccentric, placed upon the axle of the carriage. There is also a cylinder, fitted with an air-tight piston, one side of which is open to the atmosphere, the piston-rod being attached to a lever acting on the brake. A tube connects the cylinder with the vacuum chamber, and in this tube there is a stop-cock, under the control of the conductor, who has only to open the cock, and form a communication between the cylinder and vacuum chamber, where the piston, on being pressed inwards by the atmosphere, acts upon the lever of the brake, thereby transmitting a sufficient force to the carriage wheels to retard its motion. This is the process for a single carriage traversing an atmospheric railway; but where many carriages are used, the patentees propose to have a much larger vacuum vessel and air-pump, and to connect the cylinders of each carriage with the vacuum chamber by means of a flexible air-tight tube, so that when the conductor opens the vacuum chamber to this tube, all the pistons are instantly drawn inwards, and all the brakes in the train are operated on simultaneously.

The claim of the patentees extends to the method of obtaining the vacuum in the traction pipes of atmospheric railways; and to the mode of working the brakes of carriages by the pressure of the air into a

vacuum.

MESSRS. D. AND A. AULD, for an improved method of regulating the pressuré and generation of steam in steam boilers and generators. Patent dated, November 9, 1844; Specification enrolled, May 9, 1844.

This invention consists in a method of regulating the admission of water into steam boilers and generators, and the application of heat to generate the steam, so as to prevent any unnecessary waste, and thereby to diminish the expense of fuel, and render useful the heat that would be lost by the escape of surplus steam. The usual method of regulating the supply of water into lowpressure boilers is well known; the following is that proposed by the patentees. There is a cistern containing water, in which is a float-ball for regulating the supply of water from another cistern, placed at a greater elevation. From the bottom of the firstmentioned cistern proceeds an intermediate pipe or tube, connecting the cistern with the feed pipe of the boiler, the bottom of the cistern being so placed as to be level with the water in the feed-pipe when the damper is nearly shut, and at such a height as to be

regulated by the load on the safety valve, and the height of the water in the feed-pipe. When the pressure of the steam increases, so as to force the water in the feed-pipe above the level of the bottom of the cistern, the water will flow through the connectingpipe, and thereby raise the float-ball, which by rising will open a cock, and allow water to flow from the higher cistern into the feed-pipe, through a plug, which is so placed with regard to the float as not to close until the water in the boiler is considerably above the average water line. The surplus heat in the boiler is taken up by the water so admitted, and the steam is thus kept within the pressure on the safety-valve. The admission of water in this manner, and for this purpose, does not interfere with the working of the apparatus commonly in use for regulating the admission of water into the boiler.

The patentees describe a similar apparatus for regulating the admission of water into high-pressure and marine boilers; but the principle being nearly the same in each case, the particulars need not here be separately detailed. We may therefore conclude that the advantages to be attained by this invention are, that whenever the required pressure of the steam has been attained, water is admitted in sufficient quantity to absorb the surplus heat, and the damper to the fire is operated on at the same time, in such a manner as to prevent all unnecessary waste of steam and fuel.

JAMES WRIGGLESWORTH, OF BedfordSTREET, STRAND, CHEMIST, for an improvement or improvements in steel pens. Patent dated, December 2, 1844; Specification enrolled, June 2, 1845.

The nature of this invention consists in giving to steel pens any required degrees of elasticity and flexibility, combined with any requisite degrees of thickness at the points or nibs, and that by means which have not been hitherto employed, (wherefore the inventor proposes to call his pen the Eureka pen,) namely, the application of chemical instead of mechanical agents for the purpose of reducing or shaping any required part or parts of steel pens, by which means they are rendered equal for all purposes to the best or finest quill pens.

The manner in which the invention is performed is stated to be as follows:

"I first make the steel pens in the usual way of one thickness throughout, which thickness must be regulated according to that required to be given to the points or nibs; I then dip the points or nibs, and any other parts

desired to be protected, in varnish, drying oil or liquid fat, or any other matter or mixture capable of resisting the action of the chemical agents which I employ for the purpose of reducing or shaping the part or parts required. I then immerse or dip the pens to any required depth, and for any suitable time, in nitrous acid, diluted to any specific gravity, and kept at a temperature corresponding to the specific gravity, or into any other chemical substance capable of eating away, biting out, or reducing the metal to any desired extent. After this, I plunge them into hot water, if they have been protected by any fatty or oily substance, and into an alkaline mixture, if any varnish or drying oil has been, used in order to rid or free them of any of those or other matters which may be adhering thereto.

By thus making my pens of certain determined thicknesses throughout, of certain defined forms and shapes, and of any required breadth at the points or nibs, I can make them to suit all sorts of hands, and every kind of writing and drawing for which pens are required."

NOTES AND NOTICES.

of

Application of Electricity in the Extraction of Metals. At a recent meeting of the Society of Arts, Mr. Whishaw (secretary) read a paper, by Mr. Napier, "On Separating Metals from their Ores by Means of Electricity." The author's mode operation is as follows:-He uses a blacklead crucible, lined inside, within an inch or two of the bottom, with a coating of fire-clay, which is allowed to dry, and a second and third coat superadded; the ore to be operated on (which, if a sulphate, should be previously roasted) is put into the crucible, together with a little lime or other flux for the purpose of giving it fluidity. The crucible, with its contents, is then placed in a common crucible furnace; a battery of zink and copper is prepared with five pair of plates, excited by very dilute sulphuric acid; to the zink of this battery is attached an iron rod, the end of which is inserted in the furnace, and caused to touch the outside of the crucible; another rod, either of iron or copper, is used, having at one extremity a disk of iron or coke, which is made to rest on the surface of the fused mass in the crucible. The electricity is thus passed down through the whole fluid mass in the crucible, and in the course of an hour the metal is separated from the ore, and deposited at the bottom.

Singular Properties of Mercury. The extreme susceptibility of mercury, both to freeze and melt, was beautifully illustrated by Prof. Faraday, the other evening at the Royal Institution. While no number can be positively fixed to mark the fusing point of either platinum or iron, in consequence of the extreme difficulty of melting them, mercury melts at as low as 29°. By placing an admixture of ether and carbonic acid into a proper receptacle, mercury becomes also easily frozen. In this way the lecturer took a cast of a medal, by pouring on it at first the metal in its usual liquid state, and then applying the refrigerating carbonic acid and ether, when, after a short interval, the metal became solid, and a perfect cast was obtained.

con

THE object of the improvements included under the present patent is twofold, first, to improve the action of the Oscillating steam-engine, as now structed; and second, to extend the application of the oscillating principle to other engines, such as water-pumps, airpumps, fire-engines, &c. In our present notice we shall confine ourselves to the former branch of the patent, and in a future number dispose of the second.

Fig. 1 is a plan of a pair of oscillating steam-engines, constructed on Mr. Biram's improved plan; fig. 2 is a side elevation; and fig. 3 an end elevation. The arrows denote the supposed direction in which the steam and engines respectively operate.

A is the steam chest, which is divided into two parts by a steam-tight division B. C is the cylinder, which has a hollow trunnion, T, which oscillates within the steam-chest A. S is the induction pipe; E, the eduction pipe. A steamway communicates with each end of the cylinder through the trunnion T, having two ports or openings, a a, into each end, forming a passage alternately to each division. The width of these openings is made equal to about two-thirds of the angular distance travelled by the periphery of the trunnion on each side of the centre. The openings at each end of the cylinder have a valve, b b, wide enough to cover both of them, which valve is fitted accurately upon the

periphery of the trunnion, and dovetailed at each end into moveable rings, cc, fitting on to the trunnion on each side of the steam-chest. These rings, c c, have on the upper side each two notches, dd, to receive alternately the catches el e2 which are fixed upon the sides of the steam- chest, and kept in an adequate state of tension by the springs ss; ff ff are tappets, which are screwed on to the trunnion on each side of the valves, one side of these tappets radiating to the centre, for the purpose of raising the valves, and the other side forming a tangent to the circle of the trunnion, for the purpose of raising the catches.

When the cylinder is upon its centre at either end of the stroke, one port, communicating with each side of the steam-chest, and with the opposite ends of the cylinder, is half open. When the cylinder has travelled through onethird of the angular distance on either side, the ports are wide open; the tappets fl and f3, or f2 and f, then come in contact on opposite sides with the valves, while at the same instant, one of the other tappets, f2 or f1, clear the catch e2, or e1, as the case may be, and the valves travel with the trunnion through the remaining two-thirds of the distance; the other catch then drops into its notch, and retains the valves until the trunnion has travelled to one-third of its distance on the other side of the centre,