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Nothing now remains, in order to complete them for the market, but rubbing them with a strong lather of soap, washing, and blueing them.

The alcali is one of the chief articles of expense used in bleaching: and it is a great object with the bleacher to recover the pure alcali from the leys which have been used.

The sulphuret of lime, or the combination of sulphur and lime, which are both cheap articles, has been used in Ireland for bleaching, instead of potash. It was first proposed by Mr. Higgins, and it answers in some cases, particularly where the goods are intended for dying.

The sulphuret of lime is prepared as follows:-sulphur in powder, four pounds; lime, well slaked, twenty pounds; and water, sixteen gallons; are to be well mixed, and boiled for half an hour in an iron vessel, stirring them briskly from time to time. Soon after the agitation of boiling is over, the solution of the sulphuret clears, and may be drawn off free from the insoluble matter, which is considerable, and which rests upon the bottom of the boiler. The liquor in this state is pretty nearly of the colour of small beer, but not quite so transparent.

Sixteen gallons of fresh water are afterwards to be poured upon the insoluble dregs in the boiler, in order to separate the whole of the sulphuret from them. When this clears (being previously well agitated) it is also to be drawn off and mixed with the first liquor; to these again, thirty-three gallons more of water may be added, which will reduce the liquor to a proper standard for steeping the cloth. Here we have (an allowance being made for evaporation, and for the quantity retained in the dregs) sixty gallons of liquor from four pounds of sulphur.

Although sulphur, by itself, is not in any sensible degree soluble in water, and lime but sparingly so, water dissolving only about one seven hundredth part of its weight of lime; yet the sulphuret of lime is highly soluble.

After the paste used by the weaver has been removed, the linen is steeped in a solution of the sulphuret of lime, prepared as above, for about twelve or eighteen hours. It is then washed, and steeped in oxymuriate of lime. This process is repeated by six alternate immersions in each liquor.

For the use of private families, where the linen is dirtied by perspiration or grease, it will be of great service towards rendering it white, to steep it for some time in a clear liquor, made by mixing one quart of quick-lime in ten gallons of water, letting the mixture stand for twenty-four hours, and then using the clean water drawn off from the lime. After the linen has been steeped in this liquor, it should be well washed as usual, but will require much less soap to be used.

It is of great consequence in bleaching with the oxygenated muriatic acid, that it may be employed of a proper strength; as a test to ascertain its strength, a solution of indigo in sulphuric acid is used. A certain quantity is put into a glass tube, and oxygenated muriatic acid is added until the colour of the indigo is destroyed: by the quantity of acid necessary to destroy the colour, its strength is estimated.

Steam has been employed in bleaching in France with great success. The process was brought from the Levant. Chaptal first made it known to the public. When an alcaline ley is boiled, a certain quantity of alcali always rises with the steam. The

cloth is first immersed in weak caustic alcaline liquor, and placed over a chamber constructed over a boiler, into which is put the alcaline ley which is to be raised into steam. After the fire has been lighted, and the cloth has remained exposed to the action of the steam for a sufficient length of time, it is taken out, and immersed in the oxygenated muriate of lime, and afterwards exposed for two or three days on the grass.

This operation, which is very expeditious, is sufficient for cotton; but if linen-cloth should still retain a yellow tint, a second alcaline vapour-bath, and two or three days exposure on the grass, will be sufficient to give them the necessary degree of whiteness.

Bleaching of Cotton.

Cotton is a vegetable substance, and the production of a shrub that grows only in warm climates. It is a fine downy substance, in which the seeds of the plant are inclosed. Cotton, in its natural state, is generally of a dirty yellow, and opaque, being covered with a colouring matter of an unctuous nature; when this is removed, it is white and transparent.

Cotton is easier to bleach than linen. The colouring-matter is dissolved by the action of alcaline leys and washing. Sometimes the oxymuriatic acid is also used to expedite the process. Steeping in diluted sulphuric acid, is also used to dissolve the earthy matter that always remains after the immersion in alcaline ley; and as cotton is not so easily injured by acids as flax, more use is made of the acid than in the bleaching of linen. The

action of steam is very efficacious in bleaching

cottons.

In bleaching cotton for calico-printing, a pure white is not so much sought for, as that the oil may be entirely extracted.

In applying the alcaline ley, great care must be taken that no lime remains in suspension in the liquor, as it might be fixed in the cloths; and when the sulphuric acid is used, a sulphate of lime would be formed, which in fact is a mordant for the madder; hence the latter could not be discharged from those parts intended to be white.

For the same reason, the oxymuriate of lime cannot be used, if madder is to be discharged from any part of the cloth. When this is the case, oxy. muriate of potash, or of soda, is substituted for

oxymuriate of lime.

Bleaching of Wool.

The bleaching of animal substances is somewhat different from the processes employed for vegetable substances.

Wool is a sort of very fine hair which covers the bodies of some animals. Each hair is hollow, and contains an oily matter.

Wool is not easily acted upon by acids; is unalterable by water, cold or boiling; but may be entirely dissolved by strong alcaline leys. On this account, the latter must be used with great caution.

Wool is oiled before it is combed and spun, and the first operation is to free it from the oil which it has thus acquired. This is called scouring. Stale urine, which contains ammonia or the volatile alcali, is mixed with water; and the wool is im

mersed in this for about twenty minutes, heated to 56° Fahr. It is then taken out, drained, and rinsed in running water; then put into the bath of urine, and washed again. This is sometimes repeated a third time, and sometimes scouring with soap is used.

Fulling the cloth adds also to its whiteness. Fulling is a species of scouring with a particular kind of earth called fuller's earth. It effectually removes all grease, from the chemical affinity existing between the alumina contained in the fuller's earth and the oil of the cloth; and thus disposes the fibres to be entangled and matted together in the subsequent process of milling, employed to thicken the cloth, and render it stronger and firmer.

Scouring entirely with soap is preferred when the articles are valuable.

Sulphureous acid is also used for giving the last degree of whiteness.

ner.

Sulphuring is performed in the following manThe articles to be whitened are suspended uopn poles across a chamber, constructed so as to be perfectly close. Into this chamber is previously put a quantity of sulphur in dishes. When the cloth is in, the sulphur is set fire to, and the doors of the chamber are accurately shut, and all the interstices carefully stopt up, so as to exclude entirely the atmospheric air.

for

The combustion of the sulphur produces a vapour which is the sulphureous acid; this destroys the colouring matter of the wool, which is consequently rendered white. The time necessary this process varies from six to twenty-four hours. The cloth is left in the chamber for some time after the combustion of the sulphur has ceased; it

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