(1.) BLE

INTRODUCTION.

LEACHING may be defined, the art of whitening linen cloth, thread, &c. It is a process of confiderable importance to manufactarers, and one in which fome material improve ments have been lately introduced.

(2.) We shall firft defcribe the methods, which, with fome few variations, have been practifed in this country by the bleachers, and which moft of them still adhere to: and, after taking notice of the late chemical improvements of the old method, give an account of the new process, for which We are chiefly indebted to the French chemifts in general, and M. BERTHOLLET in particular.

PART I.

OF THE OLD OR COMMON METHOD OF BLEACHING.

SECT. I. Of BLEACHING in GENERAL. (3.) The process of bleaching is for the moft part conducted in the following manner, by those beechers who have not yet availed themfelves of the late difcoveries.

(4.) As foon as the cloth, which is intended to be bleached, has been forted into parcels of an equal fineness, each parcel is latched, linked, then steeped. I. STEEPING is the firft opetion which the cloth undergoes, and is thus perbmed: the linens are folded up diftinctly, and am a large wooden veffel; into which is thrown, Blood-warm, a fufficient quantity of water, or equal parts of water and ley, which has been used to whiten cloth only, or water with rye-meal or bran mixed with it, till the whole is thoroughly wet, and the liquor rifes over all. A cover of wood is then laid over the cloth, and fecured with a poft between the boards and the joifting, to prevent the cloth from rifing, during the fermentation which enfues.

(5.) About fix hours after the cloth has been teeped in warm water, and about 12 in cold, babes of air arife; a pellicle is formed on the Surface of the liquor, and the cloth fwells when it VOL. IV. PART I,

is not preffed down. This effect continues from 36 to 48 hours, according to the warmth of the weather; about which time the pellicle or feuni begins to fall to the bottom. But before this precipitation happens, the cloth must be taken out, and the proper time for taking it out is when no more air-bubbles arife. The cloth must now be well rinfed, difpofed regularly by the felrage, and wathed in the put-mill to carry off the loofe duft. After this it is to be spread on the field to dry; and when thoroughly dried, it is then ready for bucking.

(6.) II. The 2d operation, BUCKING, or the application of falts, is thus performed: The firft, or mother ley, is made in a copper, which we shall fuppofe, when full, holds 680 gallons of water. The copper is filled three fourths full of water, which is brought to boll: just when it begins, the following proportion of alles is put into it, viz. 3oib. of blue, and as much white pearl afhes; 200lb. of Marcoft afhes (or, if thefe cannot be got, about 300lb. of Cafnub); 300lb. of Muscovy, or blanch aihes: the three laft ought to be well pounded.

(7.) This liquor is allowed to boil for a quarter of an hour, stirring the afhes from the bottom very often; after which the fire is taken away. The liquor must stand till it has settled, which takes at leaft fix hours, and then it is fit for the operation.

(8.) Out of the first, or mother ley, the fecond, or that ufed in bucking, is made in this manner. Into another copper, holding 160 gallons, are put 150 gallons of water, 2lb. of foft foap, and 8 gal lons of mother ley; or, for cheapnefs, in place of the foap, when they have ley which has been used to white linen, called white linen ley, they take 56 gallons of it, leaving out an equal quantity of water. This is called BUCKING LEY.

(9.) The linens, after being taken up from the field to dry, are fet in the vat or cave in rows, endwife, that they may be equally wetted by the ley; which, made blood-warm, is now thrown on them, and the cloth is afterwards trodden down by a man with wooden fhoes. Each row undergoes the fame operation, until the veffel is full, or all the cloth in it. At first the ley is put on milkwarm, and, after ftanding a little time on the cloth

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