OIL-MILL

OIL-MILL, a mill for expressing the oils from fruits, or grains, &c. As these kingdoms do not produce the olive, it would be needless to describe the mills which are employed in the southern parts of Europe. We shall content ourselves, therefore, with a description of a Dutch oil-mill, employed for grinding and pressing linseed, rape-seed, and other oleaginous grains. Farther, to accommodate our description still more to our local circumstances, we shall employ water as the first mover; thus avoiding the enormous expence and complication of a windmill.

In Plate XXXVIII. fig. A,

Fig. B.

3. The swallower, or axis for raising the pestles. It is furnished round its circumference with wipers for lifting the pestles, so that each may fall twice during one turn of the water wheel, that is, three wipers for each pestle.

4. A frame of timber, carrying a concave half cylinder of bell-metal, in which the wallower (cased in that part with iron plates) rests and turns round. It will be seen in profile, fig. G.

5. Masonry supporting the inner gudgeon of the water wheel and the above-mentioned frame.

6. Gudgeon of the wallower, which bears against a bell-metal step fixed in the wall. This double support of the wallower is found to be necessary in all mills which drive a number of heavy stampers.

Fig. C, Is the elevation of the pestle and press-frame, their furniture, the mortars, and the press-pestles.

6. A beam a little way behind the pestles. To this are fixed the pulleys for the ropes which lift and stop the pestles. It is represented by 16 in fig. M.

7. The said pulleys with their ropes.

8. The driver, which strikes the wedge that presses the oil.

9. The discharger, a stamper which strikes upon the inverted wedge, and loosens the press.

10. The lower rail with its cross pieces, forming the lower guides of the pestles.

11. A small cog wheel upon the wallower, for turning the spatula, which fits about the oil-feed in the chauffer-pan. It has 28 teeth, and is marked N° 6 in fig. M.

12. The four standards, mortised below into the block, and above into the joists and beams of the building.

13. The six mortars hollowed out of the block itself, and in shape pretty much like a kitchen pot.

14. The feet of the pestles, rounded into cylinders, and shod with a great lump of iron.

15. A board behind the pestles, standing on its edge, but inclining a little backwards. There is such another in front, but not represented here. These form a sort of trough, which prevents the feed from being scattered about by the fall of the pestles, and lost.

16. The first press-box (also hollowed out of the block), in which the grain is squeezed, after it has come for the first time from below the millstones.

17. The second press-box, at the other end of the block, for squeezing the grain after it has passed a second time under the pestles.

18. Frame of timber for supporting the other end of the wallower, in the same manner as at N° 4. fig. D.

19. Small cog wheel on the end of the wallower for giving motion to the millstones. It has 28 teeth.

20. Gudgeon of the wallower, bearing on a bell-metal socket fixed in the wall.

21. Vessels for receiving the oil from the press-boxes.

22. Joists supporting the block.

Fig. D. Elevation and mechanism of the millstones.

1. Upright shaft, carrying the great cog wheel above, and the runner millstones below in their frame.

2. Cog-wheel of 76 cogs, driven by N° 19. of fig. C.

3. The frame of the runners. This will be more distinctly understood in N° 4. fig. H.

4. The innermost runner, or the one nearest the shaft.

5. Outermost ditto, being farther from the shaft.

6. The inner rake, which collects the grain under the outer runner.

7. The outer rake, which collects the grain under the inner runner. In this manner the grain is always turned over and over, and crushed in every direction. The inner rake lays the grain in a slope, of which fig. O. is a section; the runner flattens it, and the second rake lifts it again, as is marked in fig. P; so that every side of a grain is presented to the millstone, and the rest of the legger or nether millstone is so swept by them, that not a single grain is left on any part of it. The outer rake is also furnished with a rug of cloth, which rubs against the border or hoop that surrounds the nether millstone, so as to drag out the few grains which might otherwise remain in the corner.

8. The ends of the iron axle which passes through the upright shaft, and through the two runners. Thus they have two motions: 1^mo, A rotation round their own axis. 2^do, That by which they are carried round upon the nether millstone on which they roll. The holes in these millstones are made a little widish;

and the holes in the ears of the frame, which carry the ends of the iron axis, are made oval up and down. This great freedom of motion is necessary for the runner millstones, because frequently more or less of the grain is below them at a time, and they must therefore be at liberty to get over it without straining, and perhaps breaking, the shaft.

9. The ears of the frame which lead the two extremities of the iron axis. They are mortised into the under side of the bars of the square frame, that is carried round with the shaft.

10. The border or hoop which surrounds the nether millstone.

11. and 12. The nether millstone and masonry which supports it.

Fig. E. Form of the wallower, shewing the disposition of the wipers along its surface.

1. Two parts of this shaft, which are nicely rounded, and fortified with iron plates, and which rest upon the bell-metal concaves, which are represented in n° 4. of fig. C.

2. The little wheels at each end, for giving motion to the two spatulæ, marked n° 11. fig. C.

3. The wipers for the second press.

4. The wipers for the first press.

5. The wipers for the six pestles.

Fig. F. Represents the surface of the wallower unfolded into a rectangular parallelogram, in order to shew the distribution of the wipers, and consequently the succession of the strokes given by the different pestles. This distribution has something peculiar. Each pestle has three wipers; and there are also three for the driver and discharger of the second press. The driver and wiper of the first press have but one and a half; one for the driver, and the half for the discharger; so that it strikes twice, and the driver only once, in a turn of the shaft. This is the Dutch practice, which differs from that of Flanders. The succession of the strokes may be conceived as follows: Reckon the stampers, including those of the presses, from the water wheel toward the other end of the wallower, and calling them a, b, c, d, e, f, g, h, i, k, and supposing that a makes the first stroke, they proceed in the following order for one turn of the wallower:

ab, d, f, b, e, g, ab, d, f, b, e, g, ab, d, f, b, e, g.

Here it may be observed that a and b strike together. They would do so if allowed; but one of them is held up by its detent till the workman sets proper to disengage it. Each pestle, and the driver and discharger of the second press, makes three strokes for one turn of the wallower. But the driver k of the first press makes only one stroke in that time, namely, in the interval between the last strokes of e and g. The discharger i of this press makes two strokes; one of them in this same interval, and the other along with the first stroke of e. The second pressing requires a much more violent pressure than the first, because the cake must be left perfectly dry and hard.

Fig. G. Profile of the frame of timber which carries the wallower, and greatly contributes to render its motion steady.

Fig. H. Is a view of one of the millstones.

1. The nether millstones, and the masonry supporting the whole.

2. The runner.

3. A sort of case which encloses the two wings of the millstone at a very small distance from it, in order to prevent the grain which sticks to it from being scattered. There is another method practised at some mills.

Fig. I. Represents that of Sardamm. AA are two iron rods, about half an inch square, hanging on the axle, on each side of the millstone. These rods are joined by a cross piece C, which almost touches the millstone. A piece of leather is put between, which rubs upon the millstone, and clears it of the grain which chances to stick to it. N^o 4. and 6. represent the ears of this frame, by which the end of the iron axle is supported, and carried round by the upright shaft n^o 5.

Fig. K. Plan of the runner millstones, and the frame which carries them round.

1, 1. Are the two millstones.

3, 3, 3, 3. The outside pieces of the frame.

4, 4, 4, 4. The cross bars of the frame which embrace the upright shaft 5, and give motion to the whole.

6, 6. The iron axis upon which the runners turn.

7. The outer rake.

8. The inner ditto.

Fig. L. Represents the nether millstone seen from above.

1. The wooden gutter, which surrounds the nether millstone.

2. The border or hoop, about six inches high, all round, to prevent any feed from being scattered.

3. An opening or trap door in the gutter, which can be opened or shut at pleasure. When open, it allows the bruised grain, collected in and shoved along the gutter by the rakes, to pass through into troughs placed below to receive it.

4. Portion of the circle described by the outer runner.

5. Portion of the circle described by the inner one.

By these we see that the two stones have different routes round the axis, and bruise more feed.

6. The outer rake.

7. The inner ditto.

8. The sweep, making part of the inner rake, occasionally let down for sweeping off all the feed when it has been sufficiently bruised. The pressure and action of these rakes is adjusted by means of wooden springs, which cannot be easily and distinctly represented by any figure. The oblique position of the rakes (the outer point going foremost) causes them to shove the grain inwards or toward the centre, and at the same time to turn it over, somewhat in the same manner as the mould-board of a plough shoves the earth to the right hand, and partly turns it over. Some mills have but one sweeper; and, indeed, there is great variety in the form and construction of this part of the machinery.

Fig. M. Profile of the pestle frame.

1. Section of the horizontal shaft.

2. Three wipers for lifting the pestles.

3. Little wheel of 28 teeth for giving motion to the spatula.

4. Another wheel, which is driven by it, having 20 teeth.

5. Horizontal axle of ditto.

6. Another wheel on the same axle, having 13 teeth.

7. A wheel upon the upper end of the spindle, having 12 teeth.

8. Two guides, in which the spindle turns freely, and so that it can be shifted higher and lower.

9. A lever, moveable round the piece n^o 14, and having a hole in it at 9, through which the spindle passes, turning freely. The spindle has in this place a shoulder, which rests on the border of the hole 9; so that by the motion of this lever the spindle may be disengaged from the wheel work at pleasure. This motion is given to it by means of the lever 10, 10, moveable round its middle. The workman employed at the chauffer pulls at the rope 10, 11, and thus disengages the spindle and spatula.

11. A pestle seen sidewise.

12. The list of ditto.

13. The upper rails, marked n^o 3, in fig. C.

14. The rail, marked n^o 5, in fig. C. To this are fixed the detents, which serve to stop and hold up the pestles.

15. A detent, which is moved by the rope at its outer end.

16. A bracket behind the pestles, having a pulley, through which passes the rope going to the detent 15.

17. The said pulley.

18. The rope at the workman's hand, passing through the pulley 17, and fixed to the end of the detent 15.

This detent naturally hangs perpendicular by its own weight. When the workman wants to stop a pestle, he pulls at the rope 18, during the rise of the pestle. When this is at its greatest height, the detent is horizontal, and prevents the pestle from falling by means of a pin projecting from the side of the pestle, which rests upon the detent, the detent itself being held in that position by hitching the loop of the rope upon a pin at the workman's hand.

19. The two lower rails, marked n^o 10, fig. C.

20. Great wooden, and sometimes stone, block, in which the mortars are formed, marked n^o 21, in fig. C.

21. Vessel placed below the press boxes for receiving the oil.

22. Chauffer, or little furnace, for warming the bruised grain.

23. Basket in the front of the chauffer, tapering downwards, and opening below in a narrow slit. The hair bags in which the grain is to be pressed after it has been warmed in the chauffer, are filled by placing them in this basket. The grain is lifted out of the chauffer with a ladle, and put into these bags; and a good quantity of oil runs from it through the slit at the bottom into a vessel set to receive it.

24. The spatula attached to the lower end of the spindle, and turning round among the grain in the chauffer pan, and thus preventing it from sticking to the bottom or sides, and getting too much heat.

Fig. N. Plan of part of the works.

1, 1. Furnaces for warming the grain.

2, 2. The buckets for holding the sacks while they are a-filling.

3, 3. The pan in which the bruised grain is heated by the chauffer.

4, 4. A trough for receiving the chips, into which the pressed oil-cakes are cut, to be afterwards put into the pan and warmed.

5. The press-box for the second pressing.

6. The press-box for the first pressing.

7. The six mortars.

8. The sloping boards, to hinder the scattering of the oil feed.

9. The nether millstone, but out of its place.
10. Its centre a little higher than the rest.
11. A rib of wood going round the edge of the nether millstone, and even with its surface, but rising a very little outwards, and surrounded with a border or hoop about an inch high, to prevent the feed from being scattered on the ground.

Fig. Q. A section, lengthwise, of the great block, with the mortars and press-boxes.

Fig. R. Another view of the press-irons.

Fig. S. The principal pieces of the press.

The foregoing enumeration and views of the different parts of a Dutch oil-mill, are sufficient, we imagine, to enable an intelligent mill-wright, to whom the machine is altogether new, to understand its manner of work-

ing, and its adaptation to the various parts of the process for extracting the oil from seeds or kernels. It would require a very minute description indeed to explain it to a person altogether unacquainted with mill-work.

The first part of the process is bruising the feed under the runner stones (a). That this may be more expeditiously done, one of the runners is set about $\backslash frac\{2\}\{3\}$ds of its own thickness nearer the shaft than the other. Thus they have different treads; and the grain, which is a little heaped towards the centre, is thus bruised by both. The inner rake gathers it up under the outer stone into a ridge, of which the section is represented in Plate XL. fig. O. The stone passes over it and flattens it. It is gathered up again into a ridge, of the form of fig. P. under the inner stone, by the outer rake, which consists of two parts. The outer part presses close on the wooden border which surrounds the nether stone, and shoves the feed obliquely inwards, while the inner part of this rake gathers up what had spread toward the centre. The other rake has a joint near the middle of its length, by which the outer half of it can be raised from the nether stone, while the inner half continues pressing on it, and thus scrapes off the moist paste. When the feed is sufficiently bruised, the miller lets down the outer end of the rake. This immediately gathers the whole paste, and shoves it obliquely outwards to the wooden rim, where it is at last brought to a part that is left unboarded, and it falls through into troughs placed to receive it. These troughs have holes in the bottom, through which the oil drips all the time of the operation. This part of the oil is directed into a particular cistern, being considered as the purest of the whole, having been obtained, without pressure, by the mere breaking of the hull of the seed.

In some mills this operation is expedited, and a much greater quantity of this belt oil is obtained, by having the bed of masonry which supports the legger formed into a little furnace, and gently heated. But the utmost care is necessary to prevent the heat from becoming considerable. This, enabling the oil to dissolve more of the fermentable substance of the feed, exposes the oil to the risk of growing soon very rancid; and, in general, it is thought a hazardous practice, and the oil does not bring so high a price.

When the paste comes from under the stones, it is put into the hair bags, and subjected to the first pressing. The oil thus obtained is also esteemed as of the first quality, scarcely inferior to the former, and is kept apart (The great oil cistern being divided into several portions by partitions).

The oil cakes of this pressing are taken out of the bags, broken to pieces, and put into the mortars for the first stamping. Here the paste is again broken down, and the parenchyma of the feed reduced to a fine meal. Thus free egrets is allowed to the oil from every vehicle in which it was contained. But it is now rendered much more clammy, by the forcible mixture of the mu-

cilage, and even of the finer parts of the meal. When sufficiently pounded, the workman stops the pestle of a mortar, when at the top of its lift, and carries the contents of the mortar to the first chauffer pan, where it is heated to about the temperature of melting bees wax (this, we are told, is the test), and all the while stirred about by the spatula. From thence it is again put into hair bags, in the manner already described; and the oil which drips from it during this operation is considered as the best of the second quality, and in some mills is kept apart. The paste is now subjected to the second pressing, and the oil is that of the second quality.

All this operation of pounding and heating is performed by one workman, who has constant employment by taking the four mortars in succession. The putting into the bags and conducting of the pressing gives equal employment to another workman.

In the mills of Picardy, Alsace, and most of Flanders, the operation ends here; and the produce from the chauffer is increased, by putting a spoonful or two of water into the pan among the paste.

But the Dutch take more pains. They add no water to the paste of this their first stamping. They say that this greatly lowers the quality of the oil. The cakes which result from this pressing, and are there sold as food for cattle, are still fat and softish. The Dutch break them down, and subject them to the pestles for the second stamping. These reduce them to an impalpable paste, stiff like clay. It is lifted out, and put into the second chauffer pan; a few spoonfuls of water are added, and the whole kept for some time as hot as boiling water, and carefully stirred all the while. From thence it is lifted into the hare bags of the last press, subjected to the press; and a quantity of oil, of the lowest quality, is obtained, sufficient for giving a satisfactory profit to the miller. The cake is now perfectly dry, and hard, like a piece of board, and is sold to the farmers. Nay, there are small mills in Holland, which have no other employment than extracting the oil from the cakes which they purchase from the French and Brabanters; a clear indication of the superiority of the Dutch practice.

The nicety with which that industrious people conduct all their business is remarkable in this manufacture.

In their oil cistern, the parenchymous part, which unavoidably gets through, in some degree, in every operation, gradually subsides, and the liquor, in any division of the cistern, comes to consist of strata of different degrees of purity. The pumps which lift it out of each division are in pairs; one takes it up from the very bottom, and the other only from half depth. The last only is barrelled up for the market, and the other goes into a deep and narrow cistern, where the dreg again subsides, and more pure oil of that quality is obtained. By such careful and judicious practices, the Dutch not only supply themselves with this important article, but annually send considerable quantities into the very provinces of France and Flanders where they bought the feed from which it was extracted. When we reflect on the high price of labour in Holland, on the want of timber for machinery, on the expence of building in that country, and on the enormous expence of wind mill machinery, both in the first erection and the subsequent

wear and tear, it must be evident, that oil mills erected in England on water falls, and after the Dutch manner, cannot fail of being a great national advantage. The châtellainie or seigneurie of Lille alone makes annually between 30,000 and 40,000 barrels, each containing about 26 gallons.

What is here delivered is only a sketch. Every person acquainted with machinery will understand the general movements and operations. But the intelligent mechanic well knows, that operations of this kind have many minute circumstances which cannot be described, and which, nevertheless, may have a great influence on the whole. The rakes in the bruising-mill have an office to perform which resembles that of the hand, directed by a careful eye and unceasing attention. Words cannot communicate a clear notion of this; and a mill, constructed from the best drawings, by the most skilful workman, may gather the feed so ill, that the half of it shall not be bruised after many rounds of the machinery. This produces a scanty return of the finest oil; and the mill gets a bad character. The proprietor loses his money, is discouraged, and gives up the work. There is no security but by procuring a Dutch millwright, and paying him with the liberality of Britons. Such unhoped-for tasks have been performed of late years by machinery; and mechanical knowledge and invention is now so generally diffused, that it is highly probable that we should soon excel our teachers in this branch. But this very diffusion of knowledge, by encouraging speculation among the artists, makes it a still greater risk to erect a Dutch oil-mill without having a Dutchman, acquainted with its most improved present form, to conduct the work. We do our duty in giving this counsel.