Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 1, 1802).djvu/312

282] precaution is necessary: they should be unsewed, and the adhering leaves carefully separated, that the whole may be equally impregnated.

Mr., chemist to the Irish Linen Board, has discovered that the oxy-muriate of lime is, in bleaching, not only cheaper, but in other respects preferable to that of pot-ash. The chemical attraction of the former is somewhat stronger than that of the latter; and, on account of this quality, it does less injury to the cloth. Alternate boilings in solutions of pot-ash, steepings in oxy-muriate of lime, exposure to the action of light, and evaporating water on the green, are found to complete within six weeks, at little more than half the expence, what otherwise cannot be performed in less than double the time.

Notwithstanding this great improvement, Mr. was anxious to diminish still farther the expence attending the process of bleaching. Convinced that the mixtures of  with , are detergents, or cleansers of the most powerful kind, he was naturally led to conjecture, that lime, which, in other respects, possesses properties nearly similar to those of the fixed alkali, might also resemble them in the detergent effect of their combination with sulphur. He made trial: a sulphuret of lime, composed of four pounds of sulphur added to twenty pounds of lime, and diluted in sixteen gallons of water, formed a solution which answered cold, just as well for the bleaching of linen, as the boiling solution of pot-ash. In consequence of this experiment, he recommends, that linen, after being perfectly cleansed from the weaver's dressing, be immersed alternately in solutions of sulphuret of lime, and of oxy-muriate of lime, namely, six times in each. By this method, linen may be completely bleached, and with a considerable saving of expence. In Ireland, it is at present almost generally adopted.

The same process, with certain convenient modifications, yet always managed upon one common principle, is applicable to the bleaching of linen, cotton, silk, and wool. It has likewise been reduced to practice in France; but in a manner less simple and skilful than in Britain and Ireland.

We shall conclude this article by abstracting the patent lately granted to Mr., for an improvement in the common process of bleaching cotton, or linen pieces: Take any kind of earth which is easily mixable with water, such as clay, marl, or Fuller's earth, or if that cannot be had, any kind of soft mud or the like, which is put into a boiler to evaporate the moisture, dried, again mixed with water, and passed through fine sieves. This powder is then mixed with quick-lime, which is slacked in the earthy mass, and forms the materials for the several buckings which the cloth is to undergo. The pieces are to be worked in the bucking tubs for a number of times, alternating this operation with rinsing and souring, as is usual in the long established method, and afterwards exposing them to the air, on the bleaching ground. The only difference in the process here employed, is the admixture of earthy mud, or clay, to the lime, so that the corrosive power of the latter is diminished, and may consequently be used more freely. In the last buck-