New Method of bleaching Cotton. 47' 



•* chemlft, Chaptal, who is much refpefted by our manufafturers. I fpeak of the art of 

 '• difcolouring piece goods in a digefler, by cauftic alkaline ley. Though our fiift at» 

 " tempts did not perfectly fucceed, we were not difcouraged. The linen was expofed 

 " to the aftlon of vapour in the apparatus, but it was not equally afFefted, as it appeared 

 " to be blotched in feveral places j we were, therefore, obliged to conftruft an apparatus, 

 " in order to unroll and feparate the goods, and to expofe the greateft furfaee poffible t<*- 

 '• the action of the vapour. Suppofe the boiler of a fleam engine, in the form of an 

 " elongated ellipfis, provided with a fafety valve, two tubes with cocks, to fliew the con- 

 " fumption of the liquor, and a mercurial gage, to afcertain the ftrength of the fteam. 

 " This boiler is bedded in mafonry, or brick work, that it may refifl: the exceffive preflure 

 *' which neccflarily takes place. In the interior part of the apparatus are fix reels, three 

 " at each end, alternating with each other, in order that the a£lion of the fteam may be 

 " more equable upon the goods. Thefe reels ate flowly and uniformly carried round 

 " by fimple tooth and pinion work of wood, and the firft motion is given to an axis 

 " which pafles out of the boiler through a ftufhng box, which prevents the efcape 

 " of vapour. At the top is an opening of about Cxteen inches diameter, with 

 " a rim or flanch, on which the cover is fitted, and firmly fecured by fcrews. Between 

 ** the two metallic faces are placed ftrips of foaked leather, to prevent the vapour from 

 " efcaping. When the cover is taken off, the workmen can enter the boiler, to difpofe 

 " the goods upon the rollers, each of which contains about fifteen or twenty pieces, 

 " making in the whole about forty-five or fixty. The raw material, namely, cunnamara 

 ** kelp, is an article of inconfiderable expence, or elfe the foda extra£led from fea fait, 

 " in which there remains indeed a fmall portion indecompofed, but which we procure at a 

 " very reafonable price. It is rendered cauftic by the addition of fome good lime^ which 

 *' is made from our Hme-ftone of Parre, with thefe a ley is formed, which is equal to 

 " fourteen degrees of our hydrometer. In this lixivium the piece goods are boiled, and 

 " then conveyed to the digefter, on the bottom of which the ley ftands to about five inches 

 *' in depth. The workman ftands upon a perforated ftage, which prevents him from^ 

 ** ftepping into the ley while he is arranging the pieces : after which, having placed them 

 ^ on the rollers, the apparatus is clofed,. the fire lighted, and the operation begins. As 

 *' foon as ebullition takes place, the handle on the outfide is inceflantly turned, and as 

 *' foon as the roller at one end is filled, the handle is fliiftedto the other roller, and the 

 "turning performed in the contrary, dire£lien. In this manner the operation is continued 

 •* till the whole of the contents is bleached. From this defcription you may eafily underftand 

 " how this operation is performed ; I ftiall, however, take the firft opportunity of fending 

 " you a plan and defcription of the apparatus, if you.wifli for further information. You 

 " are at liberty to make whatever ufe you pleafe of this account: the expence of bleaching 

 '< is not more than one farthing per yard, including coals, workmen's wages, &£.. as well 

 ** as intereft for the capital employed in th? apparatus." 



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