Fig. 1.

and the seed in the bag is reduced to a very hard solid cake, which is sold for the feeding of cattle, as it retains a considerable portion of farinaceous and other nutritive matter. Of late years the elastic force of steam has been introduced to give the necessary pressure, and the patented improvements by Mr. John Hall, jun. (of Dartford), which we have now to describe, consist in the peculiar method by which this power is applied. aa (Fig. 1) are two elliptical iron cams, firmly fixed on the horizontal shafts of two cog wheels, which gear into one another; B B bb, are massive iron plates, between which the seed bags c c, in their envelopes, are placed; d is the steam cylinder; e the piston to the same, which, when raised by the force of the steam from underneath, elevates the beam f, and the connecting rods gg; these being attached to the levers hh, turn the cams so as to press against the plates B B; which pressure is continued until the cams arrive with their longest diameters in an horizontal direction, as shewn by Fig. 2. By these means the oil is squeezed out, and received into a proper receptacle underneath. On the other side of the steam cylinder, another aparatus, similar in all respects to that shewn, is fixed, and moved by the same power; but in these the longest diameters of the cams are placed in a reverse direction, or at right angles with those in the engraving; so that when the utmost pressure is excited on one side of the cylinder by the ascent or descent of the piston, no pressure whatever is given on the other, and the bags may be removed to be emptied, and replenished with a fresh quantity of seed. The employment of elliptical cams is altered with a very great convenience, which we ought not to omit noticing. The two innermost plates B B are connected together by means of straps, as shewn at ii (Fig. 2) stretched out while the cams are exerting their pressure; when that pressure is relieved by the cams being turned into the position of these in Fig. 1, the connecting straps ii are raised, and the two plates B B are drawn towards one another; the bags are then perfectly free to be removed by the workman, to be filled again and replaced; and so on alternately, on opposite sides, at every ascent or descent of the piston. The steam pressure upon the piston, employed by the patentee, is from forty to fifty pounds upon the inch, nearly the whole of which, owing to the simplicity of the apparatus, is transferred to the end of the cams, where the power is increased according to the ratio of their surfaces, compared to that of the piston. A steam apparatus is constructed near to each pair of cams, for the convenience of heating the seeds, with means for discharging the cake and refilling the bags.

Fig. 2.

B

OF OF

In the year 1828, the Society of Arts presented Mr. Cogan with their silver medal, for the communication of a process for purifying rape and linseed oils. Mr. Cogan's process, though resembling M. Thenard's in the first part of it, is completed by the judicious introduction of steam; by means of which the oil appears to be almost entirely freed from acid, and the black feculent dregs subside in the course of twelve hours, leaving the upper portion of the oil quite clear, and greatly improved in colour, and in those qualities for which it is valued by the painter. The quantity of oil that he operates upon at once is about 100 gallons. For this, three quarts, that is about ten pounds, of sulphuric acid, oil of vitriol, is required. The acid is to be diluted with an equal bulk of

water. The oil being put into a copper pan, of the shape of a boiler, two quarts of the dilute acid are to be added; the whole is then to be stirred up very carefully for an hour or more, with a wooden scoop, till the acid is become completely incorporated with the oil, and the colour of this last has become much deeper than at first. A second similar quantity of acid is to be added, and mixed with the oil, the same as the first was; and after this the remaining third part of acid is to be added. The stirring of the oil is to continue incessantly about six hours in the whole, at the end of which time the colour of the mixture will be almost that of tar. It is then to be allowed to stand quiet for a night, and in the morning is to be transferred to the boiler; this is of copper, and has a steam pipe entering it at the bottom, and then dividing into three or four branches, each of which terminates in a perforated plate. The steam thus thrown in, passes in a very divided state into the oil, penetrates into every part of it, and heats it to the temperature of boiling water. The steaming process is to be continued for about six or seven hours, at the end of which time it is to be transferred to a cooler, of the form of an inverted cone, terminating in a short pipe, commanded by a stop-cock, and also having a stop-cock inserted in its side, a few inches from the bottom. After remaining a night in the cooler, the oil is fit to be withdrawn; for this purpose, the cock at bottom is opened, and the black watery acid liquor flows out. As soon as the oil begins to come, the cock is closed, and that in the side of the cooler is opened. From this the oil runs quite clear and limpid; the whole of that which is still turbid remaining below the upper cock. The purified oil being drawn off, that which is turbid is let out into a reservoir, where it either remains to clarify by subsidence, or is mixed with the next portion of raw oil.

The following is the patented process adopted by Mr. M. Wilks, seed crusher of Dartford, for purifying the oil from linseed, as well as other seeds, by expression. Into 236 gallons of the oil, six pounds of oil of vitriol is to be poured, and be well mixed by agitation or stirring about for three hours. Six pounds of fuller's earth is next to be mixed up and thoroughly incorporated with fourteen pounds of hot lime, and thrown into the vessel containing the oil and vitriol, when the whole is to be kept in agitation for about three hours more. The foregoing mixture is next to be turned into a boiler containing a quantity of water equal to that of the oil, and the whole is then to be boiled for another three hours, during which time the liquid is to be continually agitated by stirring. The fire may now be extinguished, and when the materials have become cool, the water may be drawn off, and the oil will be found clarified, which will become brighter and more fit for use after standing some time.

Mr. Robinson, of Edinburgh, having witnessed the difficulties and waste which take place in filtering and clearing oil from its dregs; in which operation, as it is usually conducted, a great deal of the advantage which is gained by repose and subsidence, is again lost in drawing off the oil to pass it through the filter, it appeared to him that by introducing water through a regulated aperture, and from a height sufficient to give the requisite hydrostatic pressure into the bottom of the butt of oil, and making a communication from the top of a butt, to a filter acting by ascension, all the advantages arising from refuse and subsidence would be retained, and by adapting the nature of the filter to the quality of the oil, the contents of any butt might be easily and quickly separated into three or four portions of different degrees of value. Mr. Robinson concludes by suggesting the mechanical arrangement, represented by the section of the apparatus in p. 200. n is a cistern of water which communicates by the pipe a with the bottom of the butt of oil g. f is the filter raised on feet, and standing on the heading of the butt, with which it communicates by the pipe b. e is a perforated plate above the lower chamber of the filter, and k is its discharging cock; c is the middle chamber filled with charcoal, or any other suitable substance. The partition between this and the upper chamber d, is a perforated plate, and I is the discharging pipe of that chamber. The butt containing the oil being connected with the apparatus already described, the cock of the pipe a is to be turned, which will allow the water to flow into the butt. At the same time the cock of the pipe b being opened, the upper part of the oil,

and therefore the purest, first flows into, and fills the lower chamber of the filter, and is followed by the less pure portions, according to their respective specific gravity; but as the pipe enters this chamber at the top, those impurities that are considerably heavier than the oil will subside to the bottom, and are from time to time to be discharged through the cock. The rest of the oil rises through the perforated plate, is separated from the lighter impurities by the charcoal or sand in the middle chamber, and then passes through the upper plate into the top chamber, whence it flows through the cock . The two perforated plates must rest on rings or projecting ledges, that the charcoal may be renewed and the lower plate may be taken out occasionally, and cleared of the dregs which otherwise would stop its holes.

Under the words ELAINE, and FAT, we have noticed the fine fluid oil that has received the former denomination, and which has been employed for lubricating delicate horological machinery. In this place, we have to describe an improved mode of obtaining it from olive oil by Mr. Henry Wilkinson, of Pall Mall, and which is considered to be peculiarly valuable for lubricating the pivots and other rubbing

surfaces of chronometers. The best olive oil in its recent state, possesses that peculiar bland flavour which fits it for the table, and which appears to arise principally from the quantity of mucilage and water, either held in solution, or mechanically mixed with it. By keeping one or two years in jars, a considerable portion of the mucilage and water subsides, which renders such oil not only cheaper, but better qualified for yielding a greater proportion of pure oil than that which is recently expressed from the fruit. Two or three gallons skimmed from the surface of a large jar that has remained at rest for twelve months or upwards, is preferable to any succeeding portion from the same jar, and may be considered the cream of the oil. Having procured good oil in the first instance, put about one gallon into a cast-iron vessel capable of holding two gallons; place it over a slow clear fire, keeping a thermometer suspended in it; and when the temperature rises to 220°, check the heat, never allowing it to exceed 230°, nor descend below 212°, for one hour, by which time the whole of the water and acetic acid will be evaporated; the oil is then exposed to a temperature of 30° to 360 for two or three days, (consequently winter is preferable for the preparation, as avoiding the trouble and expense of producing artificial cold); by this operation a considerable portion is congealed; and while in this state, pour the whole on a muslin filter, to allow the fluid portion to run through; the solid, when dissolved, may be used for common purposes. Lastly, the fluid portion must be filtered once or more, through newly prepared animal charcoal, grossly powdered, or rather broken, and placed on bibulous paper in a wire frame within a funnel; by which operation, rancidity (if any be present) is entirely removed, and the oil is rendered perfectly bright and colourless.

Under the article CANDLE, the reader will find accounts of several patented processes for obtaining the elaine, or pure oily principle, from the cocoa-nut, palm, and other concrete vegetable oils, so that we need not repeat them under the present head; but the extremely rude and ineffective machinery employed by the natives for expressing oils, in those countries from whence we derive our

supplies, is worthy of the attention of the British reader, as exhibiting in a strong light the advantages that might result from the introduction of improved machinery in those parts. Dr. Davy informs us that the means used by the Singalese for this purpose, consists merely of a few upright poles stuck in the ground, supporting two parallel horizontal bars between them; between these, the bags containing the seeds are put, in the manner represented in the subjoined sketch, pressure being given to the bags by means of a perpendicular

lever which forces the horizontal bars together. The native oil press employed at Madras, and other parts of the East, has somewhat more the character of a machine. The machine is large and substantial, and a great amount of animal force is wanted in operating by it. The annexed drawing is taken from a model recently brought from India and deposited in the museum of the Asiatic Society.

a represents a mortar about six feet high, usually formed out of a block of granite, but sometimes of wood; in both cases, there is as much of the substance sunk into the ground as remains above it; c is a pestle, the upper extremity of which fits loosely in the piece of timber d; at e is another piece of timber, attached by

cords to d, (by passing round the projecting pins shown) with its lower end mortised and bolted to the horizontal lever g; one of the ends of this lever is forked, as at f, so as to pass into and around a groove made in the mortar; the lower part of the mortar, enlarged in its dimensions, serves as a rest for the lever g, and to give steadiness to the apparatus. To put this machine into operation, a man sits upon the end g of the horizontal lever, which by the connecting bars e and d, cause the pestle e to press hard against the sides of the mortar, and a circular motion is given to the pestle by attaching a pair of oxen to the yoke h, who draw it round. An oil press on the same principle as this, is described by Dr. Buchanan, as being used by the oil makers of Bangalore for expressing various kinds of oil. These mills receive a quantity of seed, equal to about 2 of our Winchester bushels, to which in the course of grinding, about 2 quarts of water are gradually added. The grinding continues for six hours, when the farinaceous parts of the seed and the water form a cake, and this having been removed, the oil (about 5 gallons in quantity) is found clean and pure in the bottom of the mortar, from whence it is taken by a cup. The mill requires the labour of two men and four oxen, and grinds twice a day, thus making, in the whole, but 11 gallons per day; and if this be all that so large a machine and so great a power can perform, how miserably ineffective must be the Singalese machine we first described. The writer of this article was so forcibly impressed with this defective mode of oil-pressing a few years ago, as to lead him to devise some powerful machine, in which the combinations should be few, of the simplest kind, and that should be easily made by the roughest rural workman at a trifling expense, and be, as much as possible, selfacting. The approbation which the principle of these presses have met with from professional engineers, and the practical experience which the inventor has had of their utility and convenience in a nearly similar application, induces him to give a brief description of them in this place; in the perusal of which the reader will bear in mind that they are especially designed for the rural

manufacture of oil on the spot where the seeds grow. This machine consists simply of three pieces of wood; an upright piece is fixed firmly in the ground, (a tree would answer the purpose well,) near the lower end of which, and also at the upper extremity, are projecting pieces, the upper one forming the joint of the long horizontal lever, and the lower one the joint of the short vertical one; to strengthen these joints a strap of iron is laid over them, and round the upright post, and iron bolts are passed through each to form the centre, or