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MR. BAGGS'S CARBONIC ACID-GAS ENGINE.
[Patent dated February 9, 1842. Specification enrolled August 9, 1842.]

The theory of the new power engine, which we have now to bring under the notice of our readers, is principally based on the discoveries of modern chemistry; and it may be as well, in a few words, to advert to these discoveries, before entering into the details of Mr. Baggs's application of them.

It is generally known, that many of those gases, which were formerly deemed permanently aëriform, are not so in fact, an alteration in their physical constitution being readily effected by specific variations of pressure and temperature. Carbonic acid gas assumes the liquid form under a pressure of 36 atmospheres, or 540 lbs. to the inch, at a temperature of 32°. Ammoniacal gas becomes liquid under a pressure of 65 atmospheres, at the temperature of 50°; and very slight increments of heat are sufficient to exalt the elasticity of these bodies to such an extent, as to render them competent agents for the movement of machinery.

Attempts have accordingly been made to substitute their powers for those of steam, but, as yet, with no successful result; the failure being mainly attributable to a want of economy in their production. Now, if we could manage, by any means, to recover these gases after they had done duty in the cylinder of an ordinary engine-if we could only save them from running to waste, cause them to perform their office over and over again, and effect all this at a small expense, it will be obvious that the great difficulty which has stood in the way of previous experimentalists would be avoided, and we should have at command an exceedingly cheap and portable power. This, then, is what Mr. Baggs has done; or, at least, shown the means of doing.

Mr. Baggs proposes to generate the gas through the medium of a fixed acid and a carbonate of the volatile alkali. For instance: by pouring phosphoric acid upon carbonate of ammonia, phosphate of ammonia is produced, and carbonic acid gas is driven off; and by subjecting this phosphate of ammonia to heat, it is decomposed, ammoniacal gas is liberated, and the phosphoric acid originally employed in the first part of the process remains behind. Here, then, is the regeneration of one of the materials by the

aid only of a small quantity of fuel; and the recovery of the other is even more simple. The carbonic and ammoniacal gases, produced as above described, after performing the office of steam in an appropriate engine, are allowed, by virtue of their non-elasticity, to rush into an exhausted receiver, where they no sooner come in contact than immediate condensation ensues, with the reproduction of the exact quantity of carbonate of ammonia destroyed in the commencement of the process.

It will be observed that there are but three proximate elements concerned throughout-phosphoric acid, carbonic acid, and ammonia, which, by the consecutive influences of chemical affinity and caloric, are made to undergo a definite series of actions amongst themselves, with the resulting evolution of an enormous mechanical power.

With regard to the acid employed, Mr. Baggs does not consider it to be essential that the phosphoric should be used; any fixed acid will answer the purpose, and the boracic and sulphuric acids are offered as examples. The question of preference is one of economy alone. Phosphoric acid is one of the principal constituents of bones, and the process for its extraction is sufficiently simple. Boracic acid is found native, and may also be obtained in abundance from borax. Sulphuric acid, it is well known, is plentiful enough; and with reference to the other ingredient, carbonate of ammonia, the sources of its supply are perpetual, cheap, and abundant.

Supposing the invention to be applied to a locomotive, Mr. Baggs proposes to adopt the following routine. At any given station or line of stations, proper arrangements are to be made for carrying on the manufacture of the gases in the way we have described. As the latter are produced they are to be condensed into a liquid form, either by the chemical process of Dr. Faraday, or by the mechanical method of compression, which originated with Sir M. Isambard Brunel. The two liquids thus obtained would form the only load which the engine would be required to carry; and the carbonate of ammonia would be re-formed on the road as the liquids were expended. All the

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other parts of the process are to be conducted at the station. The engine itself is proposed to be constructed in the manner represented in the accompanying engravings.

Fig. 1 is a sectional elevation; C C C are a series of wrought iron tubes charged with liquid carbonic acid. The screws are very firmly connected together by screws and tie-bolts, and are subsequently rendered perfectly sound in all the joints by soft solder. B is a screw valve for permitting and regulating the escape of the carbonic acid. K is the induction pipe, which establishes a communication between the tubular reservoir CCC, and the cylinder D. Before the gas, however, is allowed to enter the cylinder, it is made to play round a limited portion of the circumference of the condenser E E E. FF are the eduction pipes leading from the cylinder D to the condenser. (The valve gearing is not shown in the engraving, as it is the same as that usually employed.)

Fig. 2 is a plan of the engine. A A is a tubular receptacle for liquid ammonia, similar in its general arrangement to that used for carbonic acid. G is the valve, and H the induction pipe for the ammonia. This latter is arranged in the same way as the induction pipe for carbonic acid, and the ammoniacal gas is made to circulate round another portion of the circumference of the condenser E E E.

To throw the engine into action, after it is charged with the two liquids, it will be only necessary to open the valves B and C; the carbonic acid and ammonia will immediately flash from the reservoirs in the form of gas through the induction pipes K and H; flowing into their respective cylinders, and thence escaping through the pipes F F into the condenser E, where they will enter into combination.

The condensation of the gases in E, will be attended by the evolution of a great quantity of caloric, and, in order to reduce the amount of this in the condenser, as well as to increase the elasticity of the gases before they enter the working cylinders, the induction pipes are made to embrace the condenser.

By the transfer of caloric (thus effected) from the interior to the exterior of the condenser, the pressure within will be lessened, and that without increased, the

power being thereby nearly doubled. When the stock of liquid material is consumed, it is to be replenished at the station; and the carbonate of ammonia is to be withdrawn from the condenser, EEE, by the removal of one of the hemispherical ends which are shown in the drawing.

Another mode of employing the condenser, which Mr. Baggs points out, is by effecting a solution of the salt which it contains, and allowing the liquid to flow out.

In fig. 3, is shown a contrivance for preventing the escape of any ammoniacal gas into the atmosphere. L is the piston rod; P P the stuffing-box; M M is an air tight, flexible tube, capable of extension or contraction, and fixed at one end to the stuffing-box P, and at the other end to the head of the piston rod L. If any gas escape between the piston rod and the stuffing-box, it will immediately flow down the tube N into a quantity of muriatic acid contained in the vessel O, where it will be absorbed. A muriate of ammonia will be thus formed which may be removed at intervals from the vessel O.

A still better method of promoting the escape of both the gases would probably be, to form a similar elastic covering round both piston rods, and establish a free communication between them both to the condenser.

Some mechanical difficulties may very likely arise in the course of working out Mr. Baggs's ideas, but none which the perfect workmanship, for which our engine factories are so justly celebrated, does not justify us in expecting will be overcome. The invention we consider sound in principle, and hope soon to see it applied on such a scale of practical magnitude, as will effectually determine the question of its practical utility.

DOCTOR PAYERNE'S METHOD OF PURIFYING THE ATMOSPHERE OF A DIVING BELL.

Sir,—Of all the wonders of the present age, there is, perhaps, not one that has attracted more universal attention than the fact, proved by Dr. Payerne, that a man may exist several hours below water without having any communication whatever with the external atmosphere, and it not being altogether known how the

doctor purifies the air, which, like other men, he must vitiate by respiration, I beg the favour of your giving publicity in your journal to the following remarks, lest, from the desire that now so universally exists of applying to practical purposes whatever discoveries are made in science, any one should think of repeating Dr. Payerne's experiments with such means only as he APPEARS to avail himself of.

It is well known that Dr. Payerne takes with him into the diving bell an air pump, and a vessel containing cream of lime and potash, and that he has therefore all the requisites for abstracting from the air the carbonic acid gas generated by respiration; but that body being formed by the combination of the oxygen of the air with the carbon of the blood, the question arises, how does he replace the oxygen consumed? It is evident, that if it be not restored to the air, the functions of the lungs cannot be properly performed, and death must soon ensue.

Chemical science does not show how the oxygen could be extracted from the carbonic acid gas generated and absorbed by the lime, nor does it appear how it could be obtained from the water in sufficient quantity for use, even supposing the apparatus used for decomposing water to be at hand, and that the hydrogen could be got rid of, and it therefore seems to me, that it must be taken into the bell in a compressed form in some part of the doctor's apparatus. Supposing this to be the case, the expense of the application of Dr. Payerne's discovery to the common diving bell, compared with that of the air pump, may readily be ascertained by those who are familiar with the use of that instrument.

An adult consumes about 125 cubic fect of air per day, equal to 25 or 26 cubic feet of oxygen, or rather more than 1 cubic foot per hour, and this quantity cannot be made and compressed into a vessel at a less expense than 18. per cubic foot. To the expense of the gas is to be added that of the apparatus, such as the air pump, vessels to contain the gas, &c. ; but it appears to me, that if, instead of the air pump that is used in the bell for forcing the air through the lime, a silk bag moving in a frame were adopted, a far more efficient machine would be obtained at a considerably less expense. To exhaust a vessel of its air, such as the re

ceiver of an air pump, a machine capable of resisting great atmospheric pressure, and of great powers, is absolutely necessary; but where the pressure on the inside and the outside is the same, no such strength or power can be required—even a common pair of bellows would, I should think, answer every purpose required.

Dr. Payerne's method of purifying the atmosphere of a diving bell is a very ingenious and a highly philosophical application of chemical science, and oue that will afford the means of definitely ascertaining the effect of respiration on the atmosphere; any attempt therefore, on his part, to throw the veil of mystery over that which he has done, can have no other effect than to detract from the praise he is so justly entitled to."

London Mechanics' Institution, November 8, 1842.

F. C.

HOW TO MAKE AN ALLOY OF LEAD AND IRON BY THE ELECTROTYPE PROCESS.

Sir,-You expressed an opinion, a short time back, that no perfect alloys of any of the metals have as yet been performed by the electrotype process. Now, I have deposited on copper an alloy of lead and iron, two of the most difficult metals to make an alloy of; and, as it may be interesting to some of your readers, I will describe the very simple process of doing so.

In a nitric solution of lead I put a solution of sulphate of iron (copperas ;) the solution was cold, and not very strong; -when the solution was too strong, the sulphate of lead did not precipitate, but became a black liquid, which did not

answer.

The liquor remaining, after the sulphate of lead has been precipitated in white powder, is the solution containing sufficient iron and lead to electrotype with. The alloy was much harder than lead-would not melt at a strong heat, considerably above the temperature that lead melts at-and was magnetic, yet could be cut with a knife. The most singular part of the circumstance is, that

Our correspondent is evidently not aware that Dr. Payerne has taken out a patent for his invention (in the name of Mr. Vigers,) the time for lodging the specification of which has not yet elapsed. Dr. Payerne, therefore, is doing no more than prudently availing himself of the time allowed by law for specifying his invention.- En. M. M.

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