THE BLEACHER.

Bleaching is the art by which those manufactures which have vegetable substances for their raw material, are freed from the colouring matter with which such substances are naturally combined, or accidentally stained; and the pure vegetable fibre, deprived of these coloured matters, is left to reflect the different rays of light in due proportion, so as to appear white.

Besides the spoils of animals, mankind, to supply their natural want of covering, have, in all countries, had recourse to vegetable
substances, preferring those whose fibres excelled in strength, durability, and pliancy; and experience having proved, that flax and
cotton were well adapted to such purposes, these substances have been very generally adopted, and formed into such cloths as the
skill and industry of the weavers could execute.

It would soon be observed, that the action of water, together with that of the sun and air, rendered those rude cloths whiter than
they were at their first formation; and since the first step towards refinement is to add beauty to utility, as the state of society improved, a desire to give them a pure and spotless white would naturally arise. The idea of white raiment being the emblem of inocence and peace, which seems to hare been very early entertained, would make every means for facilitating the removal of natural or adventitious stains more earnestly studied.

Accident would probably discover, that a certain degree of putrid fermentation carried of colouring matter from vegetable fibres.
Hence the practice of macerating cloth in water, mixed with putrid urine and the dung of domestic animals, which has been continued to our days.

From the earliest accounts we have; of India, Egypt, and Syria, it appears that these enlightened nations knew the efficacy of natron,
(the nitre of scripture,) an impure mineral alkali, found in these countries, for combining with, and carrying off, the colouring matters
with which cloth is stained; and it is still found in great abundance by the present inhabitants, and. used for the same purpose. We are also informed by Pliny, that the ancient Gauls were acquainted with the use of a lixivium, extracted from the ashes of burnt
vegetable, as a detergent, and knew how to combine this lixivium with animal oil to form soap.

But though these nations appear to have early acquired some knowledge of the art of bleaching, the progress of improvement which
they made in it, when compared to the advantages which some of them enjoyed, was very inconsiderable. The same practices seem
to have been handed down from one generation to another, without any material improvement. In India it would appear, that the art of bleaching, as well as that of staining of cloths of various colours, are not in greater perfection at present, than they are described to have been in the days of Herodotus. Even in Europe when the arts, after they have been once introduced, have generally made rapid progress, the art of bleaching made very slow advances till towards the end of the eighteenth century.

At this period the oxymuriattc acid, and its effects, were discovered by Scheele ; and its application to the art of bleaching, by Berthollef, has given it an impulse towards perfection unknown in the history of any other art. It now became evident that oxygen had an affinity with the colouring matters with which cotton and linen manufactures are stained ; and that, by a proper use of the alkalis, along with the oxymuriatio acid, these colouring matters could be removed, and the goods rendered white, in a space of time almost instantaneous, when compared with the former method of bleaching.

Upon these discoveries the present improved state of bleaching is founded. The machinery and utensils used in bleaching are various, according to the business done by the bleacher. Where linen or heavy cotton cloths are whitened, and the business is carried on to a considerable extent, the machinery is both complicated and expensive. It consists chiefly of a water-wheel, sufficiently powerful for giving motion to the wash-stocks, dash-wheels squeezers, &c. with any other operations where power is required.

After the process of washing by the dash-wheel, the water is compressed from the cloth by means of .sqeezers. The boilers used bleaching, are of the common form, having a stop-cock at bottom for running off the white ley.They are commonly made of cast iron
and are capable of containing from tbree hundred to six hundred gallons of water, according to the extent of the business done.

The substances used in bleaching, are chiefly pot and pearl ashes, soda, soap, oxymuriate of potash, oxymuriate of lime, manganese,
muriatic acid, and sulphuric acid.

The common operations of bleaching, consist of steeping, bucking, boiling, imrersion in the oxymuriatic acid, souring, washing, &c

Steeping, is a process made use of for cleaning the cloths designed to be bleached, from the substances used by the weavers in their
manufacture, and is principally effected by means of an alkaline ley at a blood~heat.

Bucking is one of the most important operations in the bleaching of linen goods : it consists in boiling the cloths in caustic alkaline ley, by a heat gradually raised, and thereby dissolving, and taking off their colouring matter.

Boiling, in the bleaching of linen cloth, is only used when the goods are nearly white with pearl ashes alone, or with pearl ashes
along with soap, towards the end of the whitening process.

Immersion in the oxymwriate of potash: The linens, after being clean washed, are steeped in it for twelve hours, then drained, and washed for being farther bucked or boiled.

Souring is, in general, the last or finishing process in bleaching, as afterwards the linens are o«ly further washed in spring water, in
order to their being blued and made up for the market. In preparing the sour, into a large tub lined with lead, as much sulphuric acid is added to water as will give it the acidity of strong vinegar. The acid and water must be well mixed together before immersing the
linens, which are generally steeped in it for twelve hours.

Where washing is mentioned, it must be always understood that the linen is taken to the wash-stocks, or dash-wheel, and washed well in them for some hours. This part of the work can never be overdone; and on its being properly executed, between every part
of the bucking, boiling, steeping in the oxyinuriatic acid, and souring, not a little of the success of bleaching depends. By exposure,
is meant that the linen cloth is taken and apread upon the bleach-green, for four, six, or eight days, according as the routine of
business calls for the return of the cloth, in order to undergo further operations.

There are a variety of processes adopted for the bleaching of goods of different degrees of fineness : muslin, for instance, requiring a
process varied from that adopted for coarse linen ; and more delicacy is still necessary in bleaching coloured cottons and pulicatea into which permanent colours are woven.