to be wanting in strength. When the vender was charged with the intended fraud, he, at first, denied it, for he knew of no human means which could have effected the discovery; but, on the exact quantity of spirits, which had been missed, being specified, a superstitious dread seized him, and having confessed his roguery, he made amends. On the instrument of his detection being afterwards shewn to him, he offered any price for what he foresaw might be turned to great account in his trade.

Having described the hydrometer, it remains only to remark that in order to ascertain exactly, the quantity of pure alcohol in any portion of the mixture of that material, M. Gay Lussac has constructed an alcohometer. The scale is divided into 100 degrees; each of these degrees indicates the proportion of pure alcohol contained in 100 parts of mixture. Thus, for instance, when the instrument indicates 25°, it signifies that 100 parts of the liquor submitted to proof, contain 25 of pure alchohol, and 75 of water-pure alcohol indicates 100. Pure alcohol cannot be frozen though rectified spirits may, by the rapid evaporation of sulphurous acid. According to Saussure, alcohol consists of

being, as already observed, the constituent principles of sugar. Although the standard specific gravity of alcohol is rated at .825, yet experimentalists have obtained it so low as .791, and at the intermediate degrees of .817, .809, .804, .799, .797, and .796. Alcohol is co'ourless, has a fragrant odour, and a highly pungent taste; it is very inflammable, burning with a blue flame without smoke: during its combustion, water and carbonic acid are formed, the quantity of the water exceeding that of the alcohol consumed. It combines with water in every ratio, and their union is accomplished with a considerable evolution of heat, and the bulk of the liquor is less than that of the two before their admixture. The highest rectification of this spirit is called absolute alcohol, from its being considered absolutely free from water; it is so very volatile that even at the density of 820, it will boil at the temperature of 176° Fahrenheit, the barometrical pressure being 30 inches. It produces considerable cold during its evaporation; in it many of the vegetable principles and essential oils are soluble; it is the only solvent of the vegetable alkali, and is of the utmost utility in the Materia Medica.

Among the various matters from which alcohol can be extracted,

potatoes have been brought through chemical analysis to yield considerable quantities.-In conducting the process for that purpose, both in France and Great Britain, the first object is to obtain the greatest quantity of starch the potato is capable of affording. This is effected by bruising the potatoes to a pulp, then separating the starch from the dregs by means of a hair-sieve, and submitting the result to the usual process of fermentation. The preparation of starch obtained from good potatoes by French experimentalists, has been upwards of 14 cwt. of wet starch from 49 cwt. of potatoes; but the common result is from 18 to 20 per cent. of dry, or from 27 to 30 of wet starch. For a charge of 242 gallons imperial measure, from 176 to 187 lbs. of wet starch, or two-thirds of the same amount dry, are taken, thrown into a vat, and mixed with 44 gallons, or nearly half the weight of water. The mixture is then carefully stirred with rakes lest the starch should settle at the bottom; and in this state, from 110 to 132 gallons of boiling water are gradually added. The whole soon becomes thick, and is converted into a paste, or jelly. At first, it has a milky appearance, and shortly after becomes transparent, at which period it is in a proper state for undergoing the saccharine change. From 44 to 55lbs. of malt, the finer grained the better, previously softened by steeping in water are then added; ten minutes after which the material is immediately liquified, and in this state it is suffered to remain for three or four hours, during which it acquires a sensibly saccharine taste. To prepare it for fermentation, it requires a further mixture of water to make it up to about 242 gallons. To put this quantity into fermentation, nearly two quarts of good barm are considered sufficient.

Another mode of obtaining spirits from potatoes is :-Strew or spread over the bottom of a keive on which are thrown the bruised potatoes, say 883lbs. as they come from the grating machine, where they remain from a quarter to about half an hour to drain. Two workmen then commence stirring them with rakes in from 88 to 110 gallons of boiling water. The mixture soon assumes a jelly-like appearance; 55lbs. of finely-ground malt judiciously soaked are then added, and after being well agitated it is left at rest for three or four hours. All the liquor which filters through the bottom during the time, is drawn off by a cock and conducted to the fermenting tun. The mass is allowed to remain for a quarter of an hour longer, and

This valuable root is supposed to have been introduced into Europe from Virginia (North America), but it is said to have been known, at a very early period, in Tucuman, a province of Paraguay, where potatoes are termed camotes, and commonly grow to the size of seven pounds and upwards,

the liquor is drawn off as before. A second quantity of water is then added, amounting to about 44 gallons, the whole is stirred, left to drain, and the liquid thus obtained, is also sent to the fermenting tun. This treatment cools the liquid considerably, but to cool and exhaust the pulp of all the fermentable matter, which it may still contain, from 44 to 66 gallons of cold water are thrown over it, which on draining through is received into the fermenting vat with the liquid extracts. By this time the pulp on the false bottom is nearly exhausted, but retains almost three-fourths of a liquid charged with fermentable matter, which may be used to feed cattle, or may undergo another draining. In the routine of these operations the fermentable liquid is gradually cooled, till, at the end of the process, it acquires a temperature very suitable to the commencement of fermentation with a specific gravity of 1.035.

To convert the starch of potatoes into a sirup, or saccharine consistence, is the first consideration in preparing it for distillation. Kirchoff, a Russian chemist, discovered, in 1811, that sulphuric acid best effected this important purpose, by diffusing a certain quantity of the starch through water rendered pungent by a suitable proportion of the acid. The mixture is then boiled for 36 hours, stirring it carefully during the first hour, to prevent its settling at the bottom. At the expiration of that time, it becomes almost entirely fluid, and only requires stirring at intervals; accordingly, as the water evaporates, it ought to be replaced. When the liquid is sufficiently boiled, pulverized chalk is added to saturate the sulphuric acid; after cooling and settling, it possesses a sweet agreeable taste: being clarified and having evaporated to the consistence of sirup, it acquires an intense saccharine flavour and yields, on cooling, crystals of sugar. In this process, Kirchoff employed common starch, and after his experiments became public, many chemists were engaged in varying and improving the discovery. Lampadius substituted the starch of potatoes for that of wheat, and altered the process of Kirchoff in other respects, for, instead of a vessel of metal, he used one of wood heated by steam from an adjoining boiler, and conveyed through pipes descending perpendicularly to the mixture at the bottom. Sir George Tuthill put into an earthen vessel a pound and a half of potato starch, a quarter of an ounce of sulphuric acid, and six pints of distilled water at a boiling heat. These he kept stirring for thirty-eight hours, adding a supply of fresh water to keep the mixture in a degree of uniform fluidity. At the expiration of twenty-four hours, it became sweet, and increased in saccharine quality during the remainder of the process. When it had boiled for thirty-four hours an ounce of finely

pulverized charcoal was infused, and, in two hours more, some fresh lime was thrown in to saturate the acid, and the boiling was continued for half an hour longer. The liquor was then strained through calico, and the residuum, consisting of charcoal and sulphate of lime, after repeated washings by warm water, was dried, and weighed seveneighths of an ounce. The clear fluid having settled to the consistence of sirup, was, in eight days, converted into a crystalline substance like common brown sugar, with a mixture of treacle. This saccharine matter weighed one pound and a quarter, and its qualities were considered as intermediate between those of cane and sirup. Professor De la Rive of Geneva, and M. Theodore De Saussure, by a further investigation of these results, found that during this process no gas is evolved, that the conversion proceeds equally well in close vessels, and that no portion of the sulphuric acid is decomposed. Whence it is fair to conclude, that the conversion of starch into sugar is nothing more than its combination with water in its solid state, or rather with its elements. M. Braconnot has recently extended still further our views concerning the artificial production of sugar and gum. He found that well-dried elm-dust, shreds of linen, &c. when treated with sulphuric acid (sp. gr. 1.827) and afterwards diluted with water, and the acid saturated with lime, yielded, by evaporation, a glutinous matter, which was convertible into a crystallized sugar, by further boiling with diluted sulphuric acid at 30° or 40°. Nothing can more satisfactorily illustrate the facility with which one proximate principle is convertible into another; and strange as the statement may appear to persons not familiar with chemical speculations, it is nevertheless indisputably true that a pound weight of rags can be easily converted into a pound weight of sugar, and be distilled into spirits.

Such was the origin of the art which has been so successfully applied to France in the manufacture of spirits from potatoes; and it has rendered the saccharizing of starch by sulphuric acid, a simple and practicable branch of manufacture.

M. Zeize has stated, that a small quantity of chloride of calcium (oxymuriate of lime) moistened with water, added to the wash made from potatoes or grain, (the liquid being allowed to subside before it is distilled) makes the spirit produced more like brandy. It is freed, he says, from the peculiar taste of all corn-spirits, and is considered as good as the brandy made from wine. The chloride must be of the best quality, and to determine the quantity necessary to be used, a

* Paris's Elements of Medical Chemistry, p. 495.

little of the wash should be first tried with it as a test of the proportion requisite.

M. Dubrunfaut, a French chemist, in his Art of Distillation, (published at Paris in 1824,) has given the results of various experiments made by him in the saccharizing and distilling of potato starch. From 4 gallons, 3 pints, to 5 gallons imperial measure of spirits at 19° (935 sp. gr.) was the ordinary quantity obtained from 110lbs. of starch saccharized by sulphuric acid; but it is thought that this could be considerably increased by various means, particularly by diluting and cooling the worts rapidly, as delay in this stage of the process tends to diminish the alcoholic principle.

When 221tbs. of starch are submitted to the action of sulphuric acid, 13 gallons of spirits of 935 degrees specific gravity are obtained. But since it is known that starch acted on by sulphuric acid, produces an equal weight of sugar, and that sugar in fermentation gives nearly half its weight of carbonic acid-gas, and the other half of pure alcohol, it is evident that this quantity is far off the actual quantity that ought to be produced; and after all the ingenuity of the chemist, what has been accomplished only proves that there is yet much to be done to perfect the process of transforming starch into alcohol.

In Sweden, an improvement in the distillation of brandy from potatoes has been lately introduced by M. Siemen of Pyrmont, who was invited to Stockholm by the government at the instance of M. Berzelius. The Danish monarch also induced him to visit Copenhagen, to communicate his plan of operations to Professor Oersted, who gave it his unqualified approbation.

The

The potatoes are heated by steam at high pressure above the temperature of 212°, and reduced to a fine pulp by the rotatory motion of an iron cross in the same vessel in which they are steamed. pulp is then diluted with hot water and a little caustic potash. One pound of potash is sufficient for three or four tons of potatoes. The effect of high steam heat is to render the pulp extremely miscible with the alkaline water, so that every thing, except the skins, readily passes through a sieve. This fine pulp is speedily cooled, and it is then fit to be fermented in the ordinary mode. A great quantity of yeast is also produced during fermentation, which serves either for future operations, or for bakers' use. M. Siemen states the product of spirit by his process to be more than one-third greater than is obtained by the common method, which amounts to 13 quarts from a ton of potaIn the experiments made, under the personal inspection of Professor Oersted, at Copenhagen, from 16 to 17 quarts of spirits at

toes.