fermentation of grain and barley should never be carried so far as to run into acetous fermentation, and form vinegar. The above quantities are to be considered as what are obtained in practice, and this of course depends very much on individual skill.

In putting up a still, the bottom part of which must be regarded only as a means of applying heat to a liquid in the most economical manner, attention must be paid to its form. Chaptal recommends that the bottom should be concave, and both fuel and time are saved by having the still very broad and shallow, and contriving a free exit for the steam. In consequence of the regulation which made the amount of duty depend on the capacity or measurement of the still, it was the distiller's interest to work off the greatest quantity of spirit possible in the shortest space of time; and hence a form of still was adopted in Scotland well calculated to run off a great quantity of spirits in a short time.

с

Fig. 1 is a section of a common flat still, calculated to answer this purpose. It has an engine for agitating the sediment and a steam plate. a is the grate; b the ash-pit; e the furnace door; d the fire, showing the flame bent backwards, and away from the still, by the air which occupies the space between the fire and still; e the body of the still;f the bottom and side scraper; g its upright shaft; h the cupmouthed aperture in the head of the still, through which the shaft enters. This cup is filled with wool and grease held down by a plate of metal, which is held down by two screws. i the copper plate, concave below, and stretching almost to the side of the still; m the large central hole in this plate, through which the air generated at the bot tom of the still rises and escapes up into the head; n the arrows represent the current of the liquor in the still above and below the plate; k the head of the still; the steam; o the chains of the scraping-machine.

Fig. 2 is an improved still of the

same species, with its sediment agitating and jet-breaking apparatus. a the still; b the turned up edge of its circular bottom; c one of the lateral steam-escape pipes; d the central steam-pipe; e the discharge-pipe. The charge-pipe being on the opposite side could not be shown. f the head, luted on, and held down by the chain, g. There is a similar chain on the other side of the support of i, the lying shaft of the bottom scrapingengine. k the cup-like aperture in the head; its cover; m m its screws; n the upright shaft of the jet and froth-breaker contained in the head, f, and upper part of the central pipe opposite to the entrance of the lateral steam-pipes, c; o the connexion between the shaft of the horizontal wheel, p, which is moved by the vertical wheel, 9; r the handle of q; s the fly-wheel; ttww the frame,

The particular motive which led to the invention and employment of this kind of still was to overreach the excise. The manufacturer was obliged to pay a duty in proportion to the capacity of his still. A committee of the House of Commons inquired into all the circumstances connected with distillation in 1798; and even with a knowledge of the first still we have described, it was supposed it could not be worked off in less than eight minutes. By subsequent improvements, however, the power was so increased, that it could be worked off and discharged in less than four minutes. In one instance it was satisfactorily proved, that a still measuring 43 gallons, and containing 16, gallons of wash, was charged and worked no less than 480 times in the space of 24 hours.

The following is Chaptal's deseription of another and a more economical mode of distilling :→

"The new distilling apparatus is a complete Woolfe's apparatus. It consists of a copper fixed in a furnace, and a series of round cauldrons, which communicate with one another by means of tubes, the whole being terminated by a worm. Wine is put in the first copper, and

in all the vessels between it and the worm. The head of the still plunges into the liquid of the first vessel to the depth of 10 or 12 inches. From the empty part of the first vessel a tube passes into the liquid contained in the second, and is inserted as deep as in the first. From the second another tube goes in like manner; and from the last a tube connects the apparatus with the worm, which is cooled in the usual manner. When the wine contained in the first vessel is heated, the vapours which rise pass into the second, and communicate a sufficiency of heat to the wine there to disengage the alcohol. The vapours from the second pass into the third, and vaporize the alcohol there contained. In this manner a middling

fire occasions an immense mass of

wine to boil, and the condensation of the vapours takes place in the worm. By this means a spirit of any strength may be obtained by taking the produce of the first vessel, of the second, or the third, and so on. If in place of putting wine in the first boiler water be substituted and wine placed in the others, a milder spirit is obtained than if the wine be used. Of course the liquid in the first vessel must be renewed as it is evaporated; but it is obvious, that whether water or wine be employed, this renewal may be effected, by various mechanical means, in such a way as not to require the operation to be stopped for this purpose till the whole of the alcohol is obtained from the wine used. This method has the great advantage of diminishing the quantity of combustible necessary, and of extracting more spirit from the same quantity of wine,

"These various ameliorations have produced a brandy much more mild than was obtained by the ancient methods.* In these

An apparatus on this principle has been tried in Britain; but the excise regulations have been found to occasion insuperable difficulties. While they exist it is impossible to introduce these new methods into our country; so that we have to thank them for being compelled to

the empyreuma was always perceptible, owing to the burning; but it has been found, that the consumers, particularly those of the north, accustomed to these burnt spirits, rejected the mild brandies; and the manufacturer has been obliged to mix them with burnt spirits, which tasted of empyreuma, to meet the taste of his customers." (To be continued.)

CASE OF POISONING.* CHARACTERISTICS OF COR

ROSIVE SUBLIMATE.

WE expected to have had a series of experiments on this substance to lay before our readers; but the friend who was to have undertaken the investigation has been suddenly called to the country:

we therefore substitute the account

(abridged) which is given of this poison and its effects, by the ceiebrated Orfila. Corrosive sublimate is the common name for the deutochloride of mercury, and is a compound of chlorine and mercury, in the proportion of 73.53 mercury, and 26.47 chlorine. It is obtained by heating mercury in chlorine. Calomel is protochloride of mercury, or mercury combined with a less quantity of chlorine; or the proportions are, mercury 84.746, chlorine 15,254.† The corrosive sublimate found in commerce, is either regularly crystallized or in white compact masses, demi-transparent towards the edges; the exterior is polished and shin

drink bad spirit at a dear rate. It is well observed by Chaptal, that" industry can only develope all its resources by having the power to try and to make use of every possible method." Nature, be it observed, bestows this power; but man, blind, beetle-eyed man, takes it from his fellows. And as long as the manufacture of spirits is restrained and regulated by a system, conceived in ignorance and executed with, severity, as long as the manufacturer must guide himself, not by chemical knowledge and the reason of the thing, but by these regulations, so long will the manufacture of ardent spirits be behind the other manufactures of the country.

* Vide Chemist, No, XXV. Ure's Dictionary. ***

ing, the interior is rough, covered with small brilliant crystals, so compressed that their sides cannot be distinguished. It tastes very acrid, caustic, styptic, and metallic, occasioning a contraction of the throat, which continues for a considerable time. Its specific gravity is about 5.1398; pulverized in an agate mortar and thrown on burning coals, it is instantly volatilized, spreading in a thick white smoke, with a strong pungent odour, (notat all resembling garlic, like arsenic) which affects the nose and throat, and frequently excites coughing. A piece of copper, quite clean, exposed to this smoke, appears tarnished, but on being lightly rubbed acquires the white and brilliant colour of mercury. Litmus paper is reddened by this smoke. Corrosive sublimate exposed to the air, loses a little of its transparency, and assumes the form of a powder at its surface. If it be formed with a little water into a paste with charcoal, and submitted to the action of fire, metallic mercury, carbonic acid, and muriatic acid are obtained. The theory of this change is as follows:-The charcoal, by the elevation of temperature and its great affinity for oxygen, takes a portion of that contained in the water and forms carbonic acid gas. The chlorine of the protochloride and the hydrogen, set at liberty by the decomposition of the water, unite to form muriatic acid, while the mercury and the excess of oxygenated gas escape in the form of gas. If a small quantity of corrosive sublimate, broken into small pieces, be dropped in a glass tube, at the bottom of which there is some caustic potash perfectly pure and melted, a portion of the sublimate escapes the action of the potash, and rising in the form of smoke, attaches itself to the sides of the tube, another portion mingles with the potash and acquires a red coJour. If the heat is continued for five or six minutes, metallic mercury, adhering in globules to the side of the tube, is obtained, oxygen gas, mixed with undecomposed corrosive sublimate, escapes

into the atmosphere, and a solid body, which is chloride of potassium, (muriate of potash) with the excess of potash employed, remains at the bottom of the tube. In this case the chlorine of the sublimate takes the potassium of the potash, while the oxygen of this alkali unites with the mercury and produces the red oxide, which imparts the colour to the mixture. But as this oxide is decomposed by heat, oxygen gas separates, and metallic mercury is produced, the presence of which may be ascertained by breaking the tube. It may happen, however, that the metallic globules are concealed by their union with a portion of the volatilized corrosive sublimate. In this case, the crust adhering to the sides of the tube must be scraped off and put into water, the subfimate is dissolved, and the globules of mercury precipitated. This experiment is equally conclusive if the potash and corrosive sublimate are mixed before being put into the tube; but in this case the mixture acquires a red colour by mere trituration. If a mixture of four parts corrosive sublimate and one part of antimony, perfectly pulverized, be gradually heated in a glass tube, chloride or butter of antimony is instantly formed, and is condensed in the upper part of the tube, a portion of the corrosive sublimate is volatilized, and at the bottom of the tube there remains metallic mercury and chloride of antimony, with, perhaps, a little, antimony. Sometimes the mercury is distinctly visible, sometimes it is hidden by the other substances; in this case the residuum is put in water, when the mercury is deposited as metallic globules. If the tube be heated more than four or five minutes, the mercury flies off; care must, therefore, be taken not to do this. It is also necessary not to put more antimony than is mentioned, for the surplus unites with the live mercury, or envelopes and conceals it. The theory of this change is, that the antimony has more affinity for the chlorine than

the mercury has, and conséquently takes it from the dentochloride; the mercury rests at the bottom. Caloric promotes this change, as it promotes all decomposition, where one of the elements is easily volatilized. Corrosive sublimate is dissolved in about eleven times its own weight of cold water; boiling water dissolves a greater quan tity. Calomel is, on the contrary, insoluble in water; and thus, if it be mixed with corrosive sublimate, the solution is not complete. The solution of corrosive sublimate is styptic, metallic, disagreeable to the taste, transparent, colourless, and without smell; it reddens litmus paper, and makes the syrup of violets green. On being distilled in a retort, to which a lengthening tube and a receiver are adapted, this solution gives a liquid, which, on condensing, can be shown to contain corrosive sublimate volatilized and water. This fact is of import ance. A saturated solution of carbonate of potash precipitates corrosive sublimate of a very dark brick colour; the precipitate being carbonate of mercury at the maximum of oxidation, hydrochlorate (muriate) of potash remains in the solution. On this carbonate of mercury being heated in a glass tube, the metal volatilizes, and attaches itself to the sides of the tube in globules. Caustic potash in alcohol, added in small quantities to a saturated solution of deuto-hydrochlorate (muriate) of mercury, precipitates it of a yellowish-red. If an excess of potash is added, the precipitate is oxide of mercury, at the maximum of oxidation, and of a beautiful yellow. In this case the potash takes the acid from the oxide; and if enough be not added, a small portion of the acid remains combined with it. In this case, on the oxide being dried, it becomes green at its surface, while it is yellow in its interior. If the solution of corrosive sublimate is extremely diluted, caustic potash gives a white, a brick, or a rosecoloured precipitate. This fact, too, is of importance. Subcarbonate of potash (salt of tartar)

forms, with a solution of corrosive sublimate, à clear brick-coloured precipitate. Lime-water produces a precipitate of rather a dark yel low; on increasing the quantity of lime, the precipitate becomes red. Ammonia produces, with the solution of corrosive sublimate, a white precipitate, which is a double insoluble salt, composed of muriate of ammonia and oxide of mercury: On being heated, it becomes first yellow, then red, and forms ammoniacal gas, azote, calomel, and metallic mercury. A small quantity of hydrosulphate of ammonia produces a grey and white precipitate with the solution of corrosive sublimate; with a large quantity the precipitate becomes quite black. The precipitate is composed of sulphur and mercury, and varies in colour in proportion as these ingredients vary, and may be perfectly red. Sulphuretted hydrogen also produces a black precipitate with the solution of corrosive sublimate.

(To be continued.)

DICTIONARY OF CHEMISTRY,

CARICA PAPAYA, papaw-tree. A remarkable plant, found in Peru and the Isle of France, which af fords a matter resembling the flesh of animals, and hence called vegetable fibrin. A white juice is also obtained from it, which is said to be a remedy for the tape-worm.

CARINTHINE. A mineral, being a sub-species of angite.

CARMINE. A red pigment prepared from cochineal. Four ounces of this latter, finely pulverized, are added to 4 or 6 quarts of distilled or rain water, previously boiled, and boiled together for six minutes. Eight scruples of Roman alum, in powder, are then added, and the whole is to be removed from the fire after one minute. When the decoction has cleared itself, decant it into large cylindrical glass vessels, covered over, and keep it undisturbed till a fine red powder is deposited. The liquor is then poured off, and the powder gradually dried. More colouring mat