being partially re-distilled in their progress, according to their degree of gravity, until the least spirituous reaches the third copper, there to undergo a new distillation.

To explain why the watery vapour is forced to return to the third copper, and is there found totally separated from the alcohol, it is sufficient to state, that water does not boil under a heat of 212° of Fahrenheit, while alcohol boils at a heat of 173°. When, therefore, the watery and alcoholic vapours rise and are successively received in one or more atmospheres of from 174° to 190°, or 200°, the watery vapour becomes separated from the alcoholic and is condensed, and the latter only passes out and is received at the desired strength, care being taken to regulate the temperature of the water contained in the uppermost copper, which is traversed by the strongest and most alcoholic vapour, before it passes into the worm.

From the foregoing particulars, it is evident that a large portion of the spirit is distilled by vapour, or steam, and is, consequently, more pure than that obtained by the ordinary apparatus. If, therefore, as is generally supposed, that all bad flavour arises from long and violent exposure of the wash to the action of the fire, this process is calculated to obviate entirely that injurious effect, and to obtain a spirit wholly divested of any empyreumatic or disagreeable taste. One distillation only is effected by the fire; this is immediately succeeded by two vapour or steam distillations, and subsequently by four purifying consecutive processes, which divest the spirit of all impurities, and it comes over, at one operation, of the strength of 35 or 40 per cent. over proof by Sykes's hydrometer.

A still of seven compartments, such as described, will produce spirits no stronger than 35 or 40 per cent. above proof; but by increasing the number of coppers or sections, there might be obtained, by a single operation, the highest pure alcohol of the chemists.

To ascertain the precise time for charging after the exhaustion of the wash in the lower copper, it is only necessary to open what is called the proof-cock placed in its side; and if the vapour issuing from it, will ignite on the application of a candle, it is evident a fresh charge is wanting. The discharge of the spent wash from the lowest vessel, the supply from the next copper to replace it, and the opening of the cock in the pipe, communicating between the charger and the top of the still to admit more wash, are all the work of about a minute, during which distillation never ceases.

The advantages of this apparatus are numerous, but may be briefly stated to consist in the saving of about two-thirds of the fuel usually

consumed; an increased produce, by economising what is lost by evaporation in the three operations, with their pumpings, &c. on the ordinary system-a considerable saving of labour, there being but one furnace, and one tail-pipe instead of three, or sometimes four. To which may be added the advantage of dispensing with low-wines and feints' receivers and chargers, together with their connexions and pumps, and the power required to put the latter in operation.

A safe of a superior nature has been constructed by Mr. Sharpe, one of the patentees; it is attached to the end of the worm, and holds a large glass cylinder in which a thermometer is suspended; at each side of this cylinder are two smaller ones in which are placed bydrometers, one for ascertaining the strength of the liquor when above, and the other when below proof. The safe is so ingeniously contrived as to enable the distiller to see the strength and colour of the spirits, and also to take a sample, which, however, is registered against him upon a dial, and no spirit can be surreptitiously obtained, while it serves to prevent fraud both on the proprietor and the revenue.

The cost of one of these stills with all its appendages, when completely ready for work, on the largest scale, is not less than from £1,600 to £1,700, but from the number of years that it will stand distillation, it may be accounted cheaper than any of those belonging to the old system, the bottom being the only part liable to injury ; but that is easily supplied, and with expense comparatively trifling. An objection has been urged against this still, that it deprives the spirit of the essential oil, which imparts that flavour so familiar to, and popular amongst Irishmen.

The apparatus invented by M. M. Adam and Duportal for producing alcohol at a single process is generally known, and those who are acquainted with Wolfe's Apparatus so common in chemical laboratories, will understand clearly the principles on which this ingenious machinery is constructed, and the full effect of its operations.

The still of Professor Solimani which has undergone improvements by Curadau is based on the principles of the still of Adam and Duportal. It consists of a boiler and three refrigeratories, and spirits of any strength can be obtained by means of it; but it is better adapted for the distillation of wine than of wash. A drawing and description of this still may be found in the Register of Arts and Journal of Patent Inventions.

Mr. Winter, a distiller in France, constructed an apparatus on the principle, that the mixed vapours of water and spirits are not condensable at the same degree of temperature, water requiring a

heat above 212° to be kept in a state of vapour, while spirits of intense strength will evaporate at a heat very little above the common atmospheric temperature. This apparatus is applicable to stills of every description, and enables the distiller to extract the whole of the spirits in the wash, at a single operation. Its great excellence consists in condensing the aqueous portion of the mixed vapour from the still before passing into the worm. To effect this purpose, the vapours from the still are first made to enter into a peculiar kind of receiver surrounded by a water-bath, the temperature of which is uniformly preserved at 170°, or thereabouts, according to the strength of the spirit required. In this receiver the aqueous particles, or those that require a heat of more than 170° to be kept în a state of vapour, are condensed, while the spirituous vapours from their superior levity pass into the second receiver. This second receiver is also of a peculiar construction, and being kept at a lower temperature than the first (at 140° or less), the whole of the weaker vapour, or that which is condensable at from 140° to 170° of temperature, is therein reduced into a liquid state, while the strong, spirituous vapour ascending alone, through certain very narrow spaces, contained between concentric cylinders, into the upper part of the apparatus, is there collected into a third receiver prior to passing into the worm. The worm is surrounded as usual with cold-water, whose powerful refrigerating effect upon the strong, spirituous vapour with which it is charged, causes it to pass rapidly into the fluid state.

With this apparatus, it is thought, the distiller would have no occasion to send his spirits to the rectifier, an attention to the temperature of the two baths being all that is required for rectification in the most perfect manner. As a confirmation of the value of the apparatus it is stated, that feints 80 per cent under proof, produced, at one operation, spirits 55 per cent over proof.

The late ingenious Mr. Watt, having ascertained that liquids boiled in vacuo at a much lower temperature than when under the pressure of the atmosphere, applied the discovery to distillation. The saving of fuel by distilling in vacuo would be immense, since it is well known that the heat of the hand in an exhausted receiver is sufficient to make water boil. All liquids boil in a vacuum at about 145° lower than in the open air, under a pressure of thirty inches of mercury; water, therefore, would boil in a vacuum of 679. After him Mr. Tritton contrived an apparatus for this purpose, which from its simplicity, is deserving of attention. The vessels are arranged in the manner of Wolfe's apparatus, as represented in the subjoined drawing, and of such strength as to bear, when empty, the external

atmospheric pressure. The vacuum is produced and maintained by air-pumps, or by the admission of steam to expel the air, and afterwards condensing the steam into water.

A is the body of the still, B is a water bath into which it is immersed, which prevents the liquor from burning or acquiring an empyreumatic flavour: Cis the head or capital, and D its neck curving downwards and entering the condensing vessel, E F is a refrigeratory or close vessel containing cold water for converting the spirituous vapours, which, having been raised in the still, are contained in the vessel E. Attached to the bottom of this vessel, is a pipe for conveying the liquid and the uncondensed vapour into a vessel G, which being surrounded with cold water contained in the vessel H, acts also as a refrigeratory and reduces the whole of the remaining vapour into a liquid state. I is an air pump for effecting a vacuum in the vessels A, E, G; K is a stop-cock for preventing any communication between the vessels E and G, when the contents of G are drawn off by the cock M, by which means a vacuum is preserved during that operation in the vessel E and the still. I is an air cock for admitting air into the vessel G to allow the contents to run out at M: N is a discharge cock, the still A. Without a vacuum being produced the matter in the still can never be heated beyond 212°, that being the greatest heat that the surrounding water is capable of receiving or transmitting.

As this apparatus affords a convenient and easy mode of removing the pressure of the atmosphere by the air-pump, the distillation is effected at the low temperature of 132°, and the regular application of so low a degree of heat cannot fail to produce a spirit of the clearest and strongest quality. On this principle of boiling in vacuo several machines have been contrived for obtaining vegetable extracts for

medicinal purposes, and it appears that they have been attended with great practical advantages. The management, it would seem, depends upon the fact, that vegetable bodies, when heated at lower temperatures than the boiling point of water, suffer less change in their essential properties than when exposed to greater heat. Dr. Arnott observes, that the essential oils of lavender, peppermint, &c. never had the natural flavour and virtues of the plants until within the last few years, since this plan was adopted.* Why should not, therefore, the produce of the vinous fermentation distilled in this way, retain more of its valuable properties than when submitted to higher temperatures under atmospheric influences.

Sir Anthony Perrier, of Cork, invented a mode of distilling by which the liquor is allowed to flow gradually in a thin stratum through a number of circular channels over a heated surface, while drag chains hanging in loops in those channels are made to revolve by the operation of a wheel and pinion. These agitate the liquor and prevent any settlement, or burning, at the bottom of the vessel. This method is not now practised, and although evincing considerable judgment and ability in the inventor, has not been productive of any eventual service worthy of further notice.

Mr. Grimble, a London distiller, obtained a patent for a still, the peculiarity of which consists in a kind of refrigeratory composed of a great number of small copper tubes placed vertically over the head of the body in the boiler. Through these, the vapours must pass in their way to the condensing worm, while, by the air circulating freely amongst them, the heat of the ascending vapour is sufficiently abstracted to cause the aqueous portion to condense and fall back into the still, so that nothing but strong spirits passes into the worm. This contrivance has the reputation of being very successful in its operations.

Mr. Evans has contrived a still of a novel character, and for which he has procured a patent. It consists of a copper cylinder, which is made to revolve vertically over the furnace by turning on a horizontal axis. A strong fire is applied to it, and the gross matter in the still is prevented from burning by the constant rotatory motion of the wash. The vapour, as it is generated, passes through the hollow axis of the still into a large worm, which also revolves horizontally upon hollow axes, through one of which the vapour enters; the

Elements of Physics, voli. pp. 386-7.

To effect a vacuum, Dr. Arnott has contrived a simple method, which, if the reader wishes to know, he will find in the volume and pages here quoted.