New Method of bleaching Cotloa. 469 



VI. 



Account of a new Method of bleaching Cotton, as puhlijhed by Chaptal, Member of the 

 National Inflilute. By J. C. Delametiierie ♦. 



T 



JL HE fuccefsful experitneots made by Berthollet in bleaching vegetable cloth, by means 

 of the oxygenated muriatic acid, feem to have brought this art nearly to a ftate of perfec- 

 tion ; but this method is not in every inftance equally ccconomical ; it requires to be per- 

 formed by fltilful operators, in order that the goods may not be affected by a ley too corro- 

 (ive, or applied at an improper time, independent of which conhderation, it is defirable 

 that every procefs fliould be completely difclofed, in order that the artitt may choofe fuch 

 means as may be bell faited to his purfuits. 



This conGderation has induced me to defcribe a very fimple and oeconomical procefs for 

 bleaching cotton thread; it is as follows: 



At the height of about four decimetres ( 18 inches) and an half above the grate of a com- 

 mon furnace, a copper boiler is placed, of a round form, five decimetres (20 inches) io 

 depth, and one metre and a third, (3^ feet) in diameter. The projeding rim of the 

 cauldron, which is about two decimetres (8 inches) refts upon the brick work of the fur- 

 nace. The remainder of the kiln is raifed of free ftone, and forms an oval boiler or di- 

 gefter about two metres (6 feet and a half) in height, and its width, when meafured at 

 the centre, is about one metre anc^ a third, or 3! feet. 



The upper part of this veffel has a round orifice about half a metre (ipj inches) in dia- 

 meter, which is ciofed, when necefliiry, by a large moveable ftone, or by a copper lid, 

 adapted for the purpofe. On the flanch of the copper veflel, which forms the bottom of 

 this kind of digefter, a grating is laid, which conCfts of bars of wood, placed near enough 

 to prevent the cotton that is put on them from falling through, and fufficiently ftrong to 

 fupport the weight of eight hundred kilogrammes, (or i '- cwt.) 



When this ftrufture is completed,the cotton having been previoufly divided into hanks or 

 parcels is flightly impregnated with a folution of foda, rendered cauftic by the addition of 

 lime. This operation is performed in a trough of wood or ftone, in which the cotton is 

 worked by men with their feet defended with wooden fhoes. As foon as the cotton is 

 fufficiently impregnated with the alkaline liquor, it is conveyed to the digefter, and piled 

 upon the wooden grate. In this fituation the exfuding liquor runs through the bars into 

 the copper boiler, where it forms a ftratum of fluid, and which allows the whole mafs to 

 be heated without danger of burning either the cotton or the metal. The alkaline ley is 

 compofed of Alicant foda, in quantity one tenth part of the weight of the cotton, and in a 

 veflel of the dimenfions above defcribed, there may be employed at each time, forty myria- 



* Journal de Phyfiquf, Vendemaire, an. 9, page 305. 



grammes 



