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a tax were laid on cotton cloth, which, for the sake of collecting this tax, prescribed that all the threads should be of one specific thickness, and all the webs of one specific strength, we could have none of that variety of texture by which every taste is now gratified, and every purpose answered by the products of our looms. Now the manufacture of spirits has been · subjected to restrictions analogous to those we have supposed to be laid on cotton. Thus the distiller is obliged, as a consequence of the law, to make his wort of a certain specific gravity, and to obtain from that a certain quantity of spirit of a specific strength. We shall boldly assert, that this is the reason why, when our knowledge of the chemistry of distillation has been so extensively increased, the spirit manufactured in our country is, compared to that manufactured in other countries, inferior both in flavour and goodness; why, for example, common English gin is so decidedly inferior to good smuggler-made malt whisky and to the gin made in Holland. In this latter country the mode of levying the tax does not compel the manufacturer to concentrate his worts so much, nor to distil so rapidly, nor to make precisely such and such a quantity, or pay for it who ther made or not; and hence he makes a liquor to suit the health and taste of his customers. Under a pretence of benefiting people, legislators restrict them to the use of a liquor which is both comparatively disagreeable and unhealthy. The mode in which the distillers strengthen their wort, is to add to it an almost saturated solution of barley and malt in hot water, till it has attained the requisite strength. It is calculated, that to obtain a gallon of spirits of the specific gravity of 0.91917, which contains 4.6lbs. of alcohol, 9.2lbs. of sugar must be decomposed. But as the distiller cannot count on decomposing above four-fifths of the sac charine matter of wort, he is compelled to raise the strength of his wort so that it may contain

11lbs. of saccharine matter for every gallon of spirits, which, whether made or not, he must pay duty for.

After the distiller has thus prepared and cooled his wort, it is run into the fermenting tub; the temperature is between 559 and 70°, according to the quantity, the season of the year, and the opinion of the distiller. Its specific gravity varies, being never less, we believe, than 1.060, and so great as 1.110. The best yeast which can be procured is added, in successive portions, during three days, and the quantity amounts to about one galJon for every two bushels of grain and malt. In three or four days the temperature rises to about 80, and sometimes to 90; great quantities of carbonic acid are disengaged, and the liquid becomes lighter. In about six or eight days the fermenting tubs are closed up, and at the end of ten or twelve days the fermentation is completed. The specific gravity of the liquid is now probably not higher than 1.000, and consists of alcohol mixed with undecomposed saccharine and farinaceous matter. The larger the proportion of alcohol, the greater the quantity of sugar, which is so much waste occasioned by the laws obliging the distiller to make his wash of a certain strength. Wort, or the mere infusion of malt and grain, is a liquid of a brownish colour and of a sweet luscious taste. When chemically examined, it appears to consist of a saccharine matter, analogous to sugar, starch, gluten, and mucilage. The principal alteration, therefore, which the wort has undergone by fermentation is, like the alteration in must by the same process, the conversion of the saccharine matter into alcohol. Wort, however, unlike must, will not ferment without the addition of yeast. It becomes, therefore, a matter of curious investigation to know what yeast imparts to the wort to induce the commencement of this process. It was ascertained by Fabroni, that a substance analogous to gluten was necessary to fermentation;

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once begun, it afterwards goes on by itself, the sugar losing in the process oxygen and carbon, which unite and escape in the shape of carbonic acid gas. Whether or not this is a correct explanation of the phenomena we will not decide, but it has probability in its favour. Water and a certain temperature, certainly above the freezing point, are absolutely necessary for fer

such a substance can be extracted from must, and it exists ready formed in the grape, though probably it is separated from the saecharine part by being lodged in the membranous part of the grape. After this substance was extracted, gluten was found to promote the fermentation, and Thenard and Seguin have found that all juices which undergo spontaneous fermentation contain a similar sub-mentation, and if the analysis of stance. It has been also ascertained that yeast contains a large quantity of a substance resembling gluten, and that if this is separated it loses the property of exciting fermentation. This peculiar substance existed in the grain, but underwent modifications during the process of malting and during the fermentation of the beer from which the yeast is separated.

the substances produced and employed be correct, it would appear that the quantity of alcohol obtained is always proportionate to the quantity of sugar which is decomposed.

As we have no plate to present our readers connected with fermentation, we have thought proper to subjoin a sketch of the spirit receiver ordered by act of parliament to be provided by all distillers. It is to be properly gauged and entered in the books of the excise officer. No. 1 is the still, 2 the worm tub, 3 the receiver, provided with a lock, and a case for inclosing and securing the lock.

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The changes which take place in the juice of fruit, or in the conversion of wort into wash or beer, have been thus explained :—It has been found that sugar dissolved in four times its weight of water, mixed with yeast, and placed in a proper temperature, ferments precisely as wort does, and yields the same products. Chemists, there- THE UTILITY OF MR. BROWN'S ENGINE DENIED. fore, have made experiments on it, as a more easy manner of deter- In the first Number of The Chemining the phenomena. Thenard mist we recorded some experi-, mixed 60 parts of yeast and 300 of ments of Sir H. Davy's on the sugar, and fermented them in a condensation of the gases, and temperature of 59°. In four or five mentioned the probable applicadays the saccharine matter had tion of this method to produce a disappeared, and 94.6 parts by moving power. In No. XVII. we weight of carbonic acid were evolve gave M. Bussy's account of a very ed. On distillation the fermented simple and apparently efficacious liquor yielded 171.5 parts of alco- means of accomplishing the same hol, spec. grav. 0.822; by evapora- object; and in our No. XVIII. we tion 12 parts of a nauseous acid mentioned Mr. Brown's invention substance were obtained, and 40 of an explosive engine. From the parts of the yeast, deprived of its specification of this engine, which azote, remained, and there was a we now subjoin, it will be evident loss of 41.9 parts. Now as sugar to our our chemical readers that its is composed proportionally of 5 moving power is in fact occasioned oxygen, 6 carbon, and 5 hydrogen, sudden condensation of and as alcohol is a compound of gases, producing a par 1 oxygen, 2 carbon, 3 hydrogen, it tial vacuum. It was lately said is supposed that the action of the by Dr. Birkbeck, in lecturing on yeast, which has a strong affinity the steam-engine," that this ma for oxygen, is to take some of it chine was at present so perfect from the saccharine matter, and as to leave nothing to be desired,}}}, that when the decomposition is It is, however, plain that we never

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desire that of which we are perfectly ignorant, and the steamengine will only appear perfect till something better is imagined or thought of. Beautiful and perfect as it is, from the following first attempt, it would seem, though we do not say that it is successful, that other means of producing a vacuum, besides the employment of steam, may possibly be advantageous.

This engine is a hydro-pneumatic one, partaking of the principles of Savery's and Newcomen's steamengine, and also of some modifications of the same principles subsequently introduced by others; but instead of condensing steam within the cylinders to effect a vacuum, the exhaustion is here to be produced by ignited gas, issuing from jets, which, by consuming the air in the closed vessels, permits the superincumbent atmosphere to force water up tubes into the va cuum chambers, and flowing thence into the periphery of a bucket water-wheel, is thereby intended to give a rotatory power for the purpose of actuating other machinery. A piston may be worked upon the principle of producing a vacuum beneath it, by burning the air in way above described; and thithe may be done in a distinct vessel, so as to communicate with several cylinders, and consequently to work several pistons at the same ime, the air and vacuum valves being opened and closed by similar means to those adapted to work the induction and eduction valves of steam-engines." bos siuke The claim of the patentee is limited to his mode of effecting a vacuum by burning gas as in a vessel, and thereby consuming the air within.

The from the engine above described, are stated to bese

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"Secondly, The engine is light and portable in its construction, the average weight being less than one-fifth theweight of a steam-engine and boiler of the same power; it also occupies a smaller space considerably, and does not require the erection of so strong a building, or of a lofty chimney. In vessels, the saving of tonnage will be highly advantageous, both in the smaller comparative weight and size of the engine, and in the very reduced space required for fuel.

"Thirdly, This engine is entirely free from danger, no boiler being used. Explosion cannot take place; and as the quantity of gas consumed is so small, and the only pressure that of the air, it is impossible that the cylinder can burst, or that the accidents incidental can occur.

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power of the engine (being derived from atmospheric pressure of from nine to ten pounds on the square inch) may be increased, with the dimensions of th the cyfinders, to any e extent, and always ascertained by the application of a mercurial gauge.

It is scarcely necessary ry to allude to the well-known fact, that, after deducting the friction arising from the use of the air

water pumps, &c. &c. and cold' general available power of the condensing

steam-engine is from seven to eight pounds per square inch.

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First, The quantity of gas consumed being very small, the e expense of working the engine is on land, the saving will be extremely great, the cost of coal ras (defens, ducting the value of the coke) 1979d'ow Indi misig loveWOR

moderate. In its applic for raising water, it constructed

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The cost of the machine will be less than that of the steamengine, particularly as constructed is, peculiarly adapted for draining or supplying rese The expense of wear and tear,

also be trifling, and when occasionally out of order, it may be repaired at a very inconsiderable cost, and with but little delay."

Since this matter was set up, which was intended for last week's Number, we have met with the following able remarks in the Scots man newspaper on the subject; and we must say, having since seen a more detailed description of Mr. Brown's engine, we are inclined to believe that they are also quite correct. At any rate, it is necessary to brnig before our readers the objections which are urged to the contrivance, more particularly as it is stated that Mr. Brown has already received numerous orders to make engines for individuals on his plan.

"The space under the piston being filled with common air, Mr. Brown introduces a quantity of inflammable gas, from time to time, by a pipe; and at each injection of gas (as we understand) ignites the mixture by bringing a jet of flame (kept at the outside of the cylinder) in contact with it. By this process the whole oxygen of the common air is burnt out, and the quantity of the elastic, fluid in the cylinder is exactly so much diminished; at the same time, the heat produced by the ignition of the gas makes the remaining air expand, and a part of it escapes by valves. Let the cylinder and the air within it now be cooled down with water applied externally, and the original quantity of air will be diminished, perhaps one-third; the piston of course descends by the pressure of the atmosphere on its upper surface, till the density of the air below equals that of the air above; that is, it will descend, not to the bottom of the cylinder, but through one-third of the space.

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Suppose that he uses pure hydrogen instead of coal gas; supposing, also, that the cylinder below the piston contains five cubic feet of atmospheric air, it will then contain fully one foot of oxygen. and four of azote. Now, by letting in two cubic feet of hydrogen, and burning it gradually as it is admit

ted, the three feet of oxygen and hydrogen will be converted into a few drops of water, and only the four cubic feet of azote will remain in the cylinder. Had the cylinder been entirely filled with oxygen, the whole could have been made to disappear by this process; a real vacuum (practically speaking) would have been obtained, and the piston would have descended to the bottom of the cylinder. As atmospheric air, however, contains little more than one-fifth of its bulk of this gas, four-fifths of the elastic fluid still remain in the cylinder; but the heat produced by the combustion of the hydrogen increases the elasticity of the four feet of azote till it exceeds that of the atmosphere, and a part of it passes off by valves. It would be troublesome to calculate how much this remaining gas will be heated by the com bustion of the hydrogen. Let us suppose that its temperature is raised from 50 to that of boiling water, though it is probably not so much; then, we know, that its elasticity would be increased onethird (from 1040 to 1376): the four cubic feet would expand to the bulk of 5 1-3d; of course one-third of a foot would be expelled; and if the cylinder and its contents were now cooled down to the original temperature, the five feet of air would be reduced by the destruction of the oxygen, and the expulsion of a small portion of the azote, to three and three-quarters cubic feet. The piston would now descend till this rarefied air (for it is absurd to speak of a vacuum) is as dense as the superincumbent atmosphere; that is, it would descend through something less than one-third of the depth of the cylinder. Such is the whole amount of the moving power, which, we verily believe, would scarcely overcome the friction of the machine during. its short descent.

"If Mr. Brown employs coal gas instead of hydrogen, and this seems to be his intention, the power, we imagine, will be still less. Assuming, as before, that the cylinder contains five cubic feet of

common air, then to destroy the one foot of oxygen included in this, he must introduce half a foot of coal gas, and the combustion yields about one foot of carbonic acid; so that there is not only no vacuum formed, but there is not even any diminution of volume effected as in the other case. The only result of the process has been to convert the oxygen of the air into carbonic acid. The gas, how ever, has a greater heating power than the hydrogen; and when it is employed, a little more of the gaseous fluid in the cylinder may be expelled by its elasticity. Mr. Brown's invention, then, will turn out to be simply an engine operating by rarefied air, a thing tried long ago, and found, we believe, to be useless.

We have no hesitation then in avowing our belief, that Mr. Brown's invention, so far as we can comprehend it, is entirely a deception, and one, we think, which could not impose upon any person who has the most moderate knowledge of chemistry and mechanics. Such imaginary improve ments are extremely common, and much money is every year thrown away in procuring patents to cover inventions which are absolutely worthless. But Mr. Brown's engine has not even the merit of being new, as we find from the following letter in the Leeds Mercury:

66 6

Having seen in your widely circulated paper of last week, an account of an explosive engine, wrought by a new power, viz, the explosion of a mixture of atmospherical air and hydrogen gas, for which, we understand, the inventors have obtained a patent; we beg leave to observe, that we believe the patentees are not the first persons who employed this new power for the propelling of engines. Having witnessed from an accident the effects of this gaseous mixture, the idea of its power was suggested to us, and we applied ourselves to construct an engine to be propelled by this powerful agency, and in the year 1819 completed one, but it being on too small a

scale, our expectations were dis-, appointed. About two years ago we completed a larger engine on the same principle, which we had in actual operation; but finding there was no saving from it, owing to the consumption of gas being so great, we abandoned the idea of it ever superseding the power of steam. To work a thirty horse. engine on the explosive principle would take more gas than the whole of the Huddersfield Gas-works are able to supply. The nitrogen gas, one of the constituents of the atmospheric air employed, being incombustible, remains in the cylinder after the explosion, and thus renders the vacuum incomplete. We have part of our first and se cond engine in existence.

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CALORIC SPECIFIC, specific heat, capacity of bodies for heat, latent heat. It is known that if we take a series of substances, such as water, oil, mercury, &c., and raise them all to the same temperature, then each of these substances, in cooling down any number of degrees, will communicate to surrounding bo dies a different quantity of heat. If, for example, we suppose them to be all at 100°, and then im-: mersed in separate masses of ice, each of them will melt a different quantity of ice in cooling down to its temperature. Again, the quantity of heat, if we may so speak, required to raise each of these bodies to the temperature of 1000 will be different; but the relation between them, under the same circumstances, is constant, and the heat which each gives out in cooling, or takes in heating, is always the same under the same eircumstances for the same body. The quantity of heat which water takes to raise it any number of degrees is assumed as unity, and then the spe. cific heat of any other body means the relation it bears to water as to the quantity of heat it gives out in

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