A dash wheel, six feet and a half in diameter, and two feet and a half wide, making twenty-two revo. lutions per minute, is the most approved size and di mensions. The Plate represents the kind used in Lancashire, and in some parts of Scotland. In the neighbourhood of London, they are a little different in the mode of the water. Instead of having the circumference close boarded, as in Lan cashire, th.y are made of sparred work : The end of the water pipe is flattened so as to make the aperture very wide and narrow ; and it is applied near the upper part of the circumference.
After the process of washing by the dash wheel, the water is compressed from the cloth by means of sq'ieezers.
Squeezers consist of a pair of wooden rollers, which, in moving, draw the cloth through between them. The lower roller receives its motion from a mill, and the uppermost is pressed down upon it by means of levers. Till of late, these rollers were fixed in strong wooden frames ; but the framing is now generally made of cast iron, which makes a neater and more durable piece of work.
Figures 4. and 5. represent one of these ma chines having a cast-iron framing, as constructed by Mr Parkinson of Manchester. A is the lower roller. B the upper roller. CD a lever which presses upon the brass of the upper roller. FE another lever to increase the power connected with CD. The extre mity of F is kept down by a pin. In some cases a weight is used in place of the pin.
The improved mode of bucking was the invention of Mr John Lowrie, a native of Glasgow. It is now practised by many bleachers in Lancashire, some on more perfect plans than others ; but we shall give the description of the kind of apparatus most appro ved of by those whose experience and skill have ren dered them the most competent judges.
In Fig. 2. Plate LVI. ABCD is the wooden kieve containing the cloth. CEFD represents the cast iron boiler. GG the ptimp. I K the pipe of com munication between the kicve and the boiler. This pipe has a valve on each of its extremities ; that on the upper extremity, when shut, prevents the ley from running into the boiler, and is regulated by the attendant by means of the rod and handle IB. The valve at K admits the ley ; in wards, prevents the steam from escaping through the pipe I K. The boiler has a steam tight iron co ver IL ; and at CD, in the kieve, is a wooden grating, a small distance above the cover of the boiler.
At MNO is a cone and broad plate of metal, hi order to spread the ley over the cloth. It is hardly necessary to say, that the boiler has a furnace, as usual for similar purposes.
While the ley is at a low temperature, the pump is worked by the mill or steam engine. When it is sufficiently heated, the elasticity of the. steam forces it up through the valves of the pump, when it is dis joined from the mill.
NP is a copper spout, which is removed at the time of taking the cloth out of the kieve.
The boilers used in bleaching are of the common form, having a stopcock at bottom for running off the waste ley. They are commonly made of cast iron, and are capable of containing from 300 to 600 gallons of water, according to the extent of the bu siness done. In order that the capacity of the boilers may be enlarged, they are formed so as to admit of a crib of wood, strongly hooped, or, what is preferable, of cast iron, to be fixed to the upper extremity of it. In order to keep the goods from the bottom of the boiler, where the heat acts most forcibly, a strong iron ring, covered with netting made of stout rope, is allowed to rest six or eight inches above the bottom of the boiler. Four double ropes are attached to the ring, for withdrawing the goods when sufficiently boiled, which have each an eye for admitting hooks from the running tackle of a crane. Where more boilers than, one are employ ed, the_crane is so placed, that. in the range of its sweep, it may withdraw the goods from any of them. For this purpose, the crane turns on spindles at top and bottom ; and the goods are raised or lowered at pleasure, by double pulleys and sheives, by means of a cylinder moved by cast-iron wheels.
Before the year 1794, the apparatus used for making the oxymuriatic acid, was so very inconve nient and defective, that the health of the work men employed was often injured, or at least their situation was rendered very uncomfortable, from the deleterious qualities of the gas. Tu remedy this defect, Mr Peter Fisher, late of Rutherglen, near Glasgow, in the year 1794, invented an ap paratus * admirably calculated for this purpose, which, with very slight alterations, has been almost universally adopted. It consists of a leaden retort A, Fig. 4. Plate LVI. set on a tripod of iron D, into a cast iron boiler B. built into brickwork, with a furnace and ash pit of the common construction EF. The top of the retort is closed with a leaden cover with screws and nuts, having an iron flenge of the same diameter above and below the mouth of the retort, with corresponding nuts and screws. The use of the flenges is to prevent the retort from being conipresscd out of shape, and thereby preventing its fitting properly. Between the joinings of the mouth of the retort, loose flax, dipt in white lead, ground in oil, is spread equally ; and the whole is firmly screwed together. In the top of the cover, a circu lar hole is made of three inches in diameter, for in troducing the materials for making the bleaching li, quor, and cleaning out the retort. The hole is fit ted with a of lead C, which is gently struck into the cover when the apparatus is arranged for working, and is luted with a little soft clay to pre vent the escape of gas.