We have already mentioned the pulp of potatoes as amongst the substances from which alcohol may be obtained; and the manufacture has been for some time past carried on in various places with great success. The apparatus and process which we are now about to describe, are both of foreign invention, and were introduced into this country by the patentee, M. Saintmarc, of the Belmont Distillery. Vauxhall. The potatoes being first washed clean, are taken to a mill and ground into pulp. This pulp is then mixed with a large quantity of water, which takes up the chief part of the contaminating brown colouring matter, and it is then poured through a coarse sieve, which, detaining those pieces that have escaped the mill without being ground into pulp, they are rejected as ineligible for fermentation, and applied to the feeding of pigs. The pulpy liquid thus freed from the coarser pieces, runs into a trough containing a number of small holes, and lined in the inside with a linen cloth sufficiently fine to prevent the floating particles of starch from passing through, the water then drains through the linen, leaving the pulp and starch to settle in a mass.

When it has sufficiently drained, and become solid and compact, it is removed from thence and laid upon a plastered floor, which rapidly absorbs a great portion of its moisture.

To dry it entirely, it is afterwards placed in a kiln or stove, which completes that part of the process. In the dry state the pulp may be kept uninjured for years, and may therefore be stored away for future use. The wet pulp being, however, equally serviceable for immediate fermentation, there is no occasion to dry it if the several processes in distillation can be carried forward at the time

Supposing the pulp to be used in the dry state, it is cut, or broken to pieces, and mixed in the vat a, with sufficient hot water to bring it to the consistence of cream. The vessel b, lined with lead, and called the decomposing vessel, is then to be supplied with water to the depth of about six inches; to this, a quantity of sulphuric acid is to be added, in the proportion of three pounds of acid to every hundred pounds of dry pulp; hut only ten pounds of the acid to every hundred pounds of the wet pulp. The diluted pulp is then to be discharged from the vessel a, through the cock into b, containing the diluted acid; steam is then to be admitted from a boiler, (not shown in the engraving,) by turning the cock in the pipe e, which descends to the bottom of the vessel, where it is made to issue from a steam-box; the heat causes the mix- ture to boil, and, after four or five hours' ebullition, the decomposition is considered complete. Before, however, describing the next part of the process, we should notice that a worm-tub d, supplied with water from a service-pipe, is placed on the top of the decomposing vessel; the vapours from the boiling liquid beneath enter this worm, and are therein condensed by transmitting their caloric to the surrounding water; and the water thus made hot, serves for replenishing the vat a with fresh portions from time to time, as it may be required, by means of a connecting tube f furnished with a stop-cock.

The contents of the vessel b, after decomposition, are discharged into the saturating vessel g, and, during the time that it is running, a quantity of lime, or chalk, in solution, may be poured in among it as long as any effervescence continues, which will vary according to the degree of concentration of the acid; but, in general, three pounds of chalk, or lime, will be found sufficient to saturate each pound of sul phuric acid employed in the preceding part of the process. The liquid in the saturating vessel having now become transparent, it is to be drawn off into the fermenting vat h, placed beneath, leaving the precipitated sediment undisturbed m is the body of the still fixed in brick-work over a furnace; a long perpendicular neck proceeds from this as in the wash-still, the object of which is, that the aqueous part of the vapour may be condensed as it ascends, and fall back again into the still, while the more volatile and spirituous passes on through the tube « to the bottom of the vessel o.

This last-mentioned vessel has a tub of cold water placed on the top of it, which is kept supplied by the service-pipe p, and as the tube n passes through this tub, the greater part of the vapour at first condenses and is received into the vessel o in a liquid form; but as the vapour is continually coming over from the still, the condensed liquor is at length made to boil: the vapour filling the upper part of the vessel, from thence passes up the tube r into the long cylindrical vessel s, which is partly immersed in a long cistern constantly supplied with cold water by the usual means. The cylindrical vessel s is divided by five vertical partitions into six compartments, but having a communication from one to the other by means of bent tubes proceeding from the upper part of the first compartment, to the lower part of the second; and, in the same manner, from the second to the third, the third to the fourth, and so on. It will now be readily seen that the most aqueous part of the vapour will be condensed in the first compartment, while the more vola tile passes to the second, where another portion of the vapour assumes a liquid form; the more volatile still will proceed to the third, and thence to the fourth, fifth, and sixth, according as the spirit is more or less divested of aqueous particles, all depending, of course, upon the degree of heat employed in the furnace for raising the vapour in the still m, and upon the degree of coldness of the water surrounding the condensing vessels.

To ensure, however, the condensation of all the vapour, a tube g proceeds from the upper part of the sixth compartment, rises to a considerable height, then takes a horizontal course, and, finally, descends into a spiral worm placed in a tub of cold water, where, making a long circuitous passage, it is delivered from the bottom into a receiver in so concentrated a form, as to be nearly in the state of pure alcohol. At the bottom of the cylindrical vessel s, a separate short pipe, with a cock, proceeds from each compartment, leading into the long pipe u, which being also furnished with a cock at either end, the spirit contained in any compartment may be drawn off distinctly; the contents of any, or all of the pipes, may likewise be drawn off by the pipe « into the vessel o for redistillation; and the vessel o may be discharged back into the still when desired, by the pipe v having a cock for that purpose. Although this apparatus is well adapted for its intended purpose, and is new in this country (where the vexatious nature of the excise laws preclude, in a great measure, any improvements in the art of distillation) we must observe that little invention has been displayed on the part of the patentee,, as almost every part of it is copied from apparatus long since invented, and in use in France.