manufacturer, since it takes up about one-half of his chlorine unprofitably, and adds a compound to his powder, probably injurious to the bleacher. Bleaching powder may be formed, which contains no appreciable proportion of the muriate of lime, as I have shown in the above memoir. By proper management the manufacturer of chloride of lime might therefore double his useful product at scarcely any additional expense.

Sulphuric Acid, or oil of vitriol, when pure, is a colorless fluid, without smell, and slightly viscid. The specific gravity of the sulphuric acid of commerce is generally 1850, about twice the weight of distilled water, but the French chemists make it 2-2553 or more. The manufacture of it is now carried on to a great extent in Great Britain. It is sometimes adulterated with lead, and supersulphate of potash; a portion of the former being taken up during its formation, in chambers of that metal; hence a white precipitate is often found in the bottom of the bottles containing it.

In popular language, sulphureous acid may be said to be a solution of sulphur in oxygen, which doubles the weight of this gas, without

Fig. 1.

augmenting its bulk. It obviously, therefore, consists by weight of equal quantities of the two constituents. Its equivalent will either be 2 oxygen + 2 sulphur 4; or 1 oxygen + 1 sulphur 2. Now the analysis of sulphite of barytes by Berzelius gives 209.22 base to 86.53 acid; which being reduced, presents for the prime equivalent of sulphureous acid, the number 4. See SULPHURIC ACID.

III. OF THE MACHINERY USED IN
BLEACHING.

This of course must be principally regulated by the scale and kind of business carried on. No pursuit has better paid for the introduction of scientific machinery, when it has been carried to any considerable extent; and, where heavy cotton cloths or linen are whitened, it requires considerable aid from machines. Amongst them a water wheel of sufficient power to give motion to the dash wheels, or wash stocks, rollers, or squeezers, &c. is conspicuous.

2. Wash Stocks are assistants in turning and washing the linen, now almost exploded; but the following diagram will show the construction:

Fig. 2.

Fig. 1. is a front and fig. 2. a side view of this invention. A, A, are the stocks or feet, suspended on iron pivots at B, and receiving their motion from wipers on the revolving shaft C. The cloth is laid in at D, and by the alternate strokes of the feet, and the curved form of the turnhead E, the cloth is washed and gradually turned; while a stream of water rushes on the cloth through holes in the upper part of the turnhead. These machines are often found in the bleaching grounds in Scotland and in Ireland; and are sometimes made with double feet, suspended above and below two turnheads, and wrought with cranks. They perform from twentyfour to thirty strokes per minute.

2. A more preferable and scientific mode of accomplishing this object is found in the use of the dash wheel, plate I. figs. 1 and 2. The pieces of cloth are put into the quadrantal compartments of the wheel, into which a stream of pure water flows through a circular slit in its posterior surface. By the rotation of the wheel, the cloth is dashed backwards and forwards between the quadrantal partitions. Twenty-five revolutions per minute is the proper speed of a wash wheel, six feet in diameter. Some persons

VOL. IV.

suppose them to perform better with twenty-six or twenty-seven revolutions. But any considerable deviation from this velocity either impairs the utility of the machine, or destroys its functions altogether. The parts are so distinctly delineated by the artist, as to supersede the necessity of letters of reference and minute explanations.

Squeezers are rollers, represented in plate II. figs. 2 and 3, whose motion draws the cloth between them, after it has passed the dash-wheel. I have here given one constructed by Parkinson of Manchester. A is the lower roller. B the upper roller. CD a lever which presses upon the brass of the upper roller. F E another lever to increase the power connected with C D. The extremity of F is kept down by a pin: in some cases a weight is used instead of it.

Plate II. fig. 1. is a bucking boiler, and exhibits the fire-place, the iron boiler, surmounted by the wooden crib, with its grated bottom, and the central iron pipe.

We come now to the most important articles of the bleachers' establishment, the apparatus for obtaining the oxymuriatic acid. This is represented in plate III.

P

Fig. 1. is a horizontal projection according to the line A' B', and a section of one of the furnaces according to CD. A, tub of immersion. B, receiver. M, M, M, M, M, plates which close exactly the space between the upper shallow tub, and the sides of the receiver. Only the side looking to the furnace is left open. Q, pipe into which the syphon for running the acid into the immersion tub is introduced. 0, 0, cross pieces which support the shallow tubs, and are fixed into the extremities, N, N, N, N, of four uprights. K, circular groove cut out in the plate, which closes the space between the second shallow tub and the side of the receiver, for the passage of the conductor tubes, one of which is traced in the figure. C, C, partition which separates the receiver from the furnaces. D, plan of a furnace, of the boiler E, serving for a sand bath, and of the matrass F. which communicates by the tube G with the intermediate bottle H, enclosed in its double box I: in the furnace, round the sand bath, and opposite each angle, channels have been cut, which serve as chimneys and registers. A section of the second furnace D is made at the height of the fire-place, that the grate d may be perceived, and the plate of iron d', which separate the fire-place from the ash-pit.

Fig. 2. Vertical section of the receiver, and of the immersion tub, according to the lines A B and CD. L, L, L, shallow tubs, separated from each other by the cross pieces O, fixed on the uprights N. The space between them and the sides of the receiver is closed by the plates M, M, M, so as to leave a free space, but on sides alternately opposite; that is to say, from the side of the furnaces to the inferior shallow tub, as also to the superior, and on the side of the immersion tub, to the middle shallow tub. P, P, P, tubes which allow the gas to pass from one shallow tub to its superior, when it contains a stratum of it, equal to the length of these tubes. The tube of the upper shallow tub is made long enough, as is shown, to disperse the gas, which being undissolved in the water, would be diffused in the air, and annoy the workmen. K, conductor tube, which proceeds from the intermediate bottle, and terminates under the lower shallow tub. Q, pipe which communicates down to the bottom of the apparatus, in order that the syphon R may conduct the most concentrated acid (aqueous chlorine) into the immersion tub. S, tube of safety. D, elevation of the furnace provided with all its distillatory apparatus.

Fig. 3. The vertical projection of the two distillatory apparatuses, according to the line D, D. The letters indicate the same objects as in the two preceding figures.

Fig. 4. The vertical section of a furnace, and of one of the boxes, with a view of showing its internal form, and the position of the sand bath. Fig. 5. Plan of a furnace without a sand bath. Fig. 6. Plan and elevation of the boiler serving as a sand bath. Fig. 7. F, matrass; T, cork of the matrass. Fig. 8. V, small syphon to draw out the air from beneath the shallow tubs. Fig. 9. I, box, with two square cells, serving to contain the intermediate bottles, drawn on a double scale. Y, small box, which encloses the bottle held in one of the cells, by the corners X, X. X, X. Fig. 10. Elevation of the same box, fur

nished with its two bottles. Plan and elevation of the small boxes Y.

Plate IV. fig. 1, 2, 3, 4, represent the apparatus for the running off lees. The same letters serve for the same objects in these different figures.

Fig. 1. Vertical section of the apparatus. A, tub. B, boiler, the bottom of which is concave, and provided with a stop-cock T. On the pipe to which this stop-cock is attached, a socket is soldered, into which the glass tube V enters, that communicates by another kneed socket with one of the wooden pipes F, which afford passage to the steam. This tube serves to show what height the liquor rises to in the boiler. The bottom of this is sustained on the edges of the interior masonry of the furnace, except in the part corresponding to the aperture S, through which the smoke passes off. Its edges are turned back on the masonry for receiving the tub, they are then raised round it, in order that the vapor and the liquid may not find an outlet between the tub and the boiler. H, grating of deal, the ribs of which rest at their ends on the edges of the masonry of the furnace, and which are supported by two bars. II, connected with the grating by four copper straps, which bear upon the corners. D, body of the pump. It has at its lower part an inverted cup, pierced with small holes, to prevent in the aspiration (sucking), the introduction of bodies, which might hinder the valves from shutting, or might scratch the body of the pump. It is prolonged by a thin copper pipe, C, which, at the upper part of the tub, carries a copper heel, on which the cylinder of copper, K, rests. This cylinder stands on four castors. It carries four sockets, to each of which an arm, X, X, is adjusted, of a length equal to the diameter of the tub, and pierced with holes, like the bulb of a watering pot. In order that the lee raised by the pump may be diffused, the pipe of the pump is perforated in like manner with small holes, in the whole portion which corresponds to the copper cylinder; and, in order that the lee may not run off by the bottom of this cylinder, it presses exactly at this part on the pipe of the pump. The arms X are fitted on like the bayonet to the muzzle of a musket; they are taken off, for the introduction and removal of the cloths. The cylinder is terminated by a ratchet wheel L, the number of whose teeth should be a prime number, in order that having no exact divisor, the arms may not be periodically brought back to the same positions. The ratchet L is set in motion by a rod a, hooked to one of the pieces of wood that form the frame-work, on which the balance-beam d of the pump rests, and fixed very freely by a pin to a horizontal rod b. This rod is fixed in like manner by its other extremity, to one of the branches of a bell movement M, whose other branch communicates by the rod c, with the balance-beam. Hence, on turning the handle e, every movement of the balance-beam is communicated to the rods, and onwards to the ratchet, which, for each stroke of the piston, percurs the space of one tooth. The body of the pump D, and the pipe C, are joined by two straps and screws. Under these straps passes an iron collar, traversed by six bolts, whose screwed ends are fixed with nuts to a copper platform placed