An EJ/ajf on Bleachhig. 263 



the Berthollimetre, there is reafon to conclude that there has 

 been an exhauflion of a fourth : the fame reafoning may be 

 applied by analogy to proofs by the acetite of lead. 



Cloth is prepared for immerfion in oxygenated water, by 

 foaking in a ley of weak potafh, and rinfing it afterwards in 

 a large quantity of water in order to free it completely from 

 the weavers' dreffing and the faliva of the fpinners. In Eng- 

 land and Ireland, machinery is employed for rinfing and 

 beating : in fome places this operation is performed by means 

 of planks to which an alternate motion is communicated; 

 but this mechanifm wears the fluffs, though it greatlv acce- 

 lerates the operation. In place of fuch planks, which are 

 too long, in our manufactories we employ flampers, placed 

 in very large conical tubs, the levers of which change their 

 direction every flroke, paffing fucceffively over the whole 

 quantity of cloth immerfed. But the befl method of all is 

 beating by mechanifm. For this purpofe a circular platform, 

 which performs its revolutions around a moveable axis, and 

 is fupported at the ends of the fpokes by rollers of caft iron, 

 is employed : the circumference of this wheel is notched to 

 receive a catch, which makes it recede one notch every flroke 

 by the motion of the mill-tree. This tree bears on its axis 

 ipokes that raife feveral wooden beaters, which, falling on 

 the moveable platform covered with cloth and thread, rinfe 

 them completely : buckets attached to the water-wheel raife 

 the water, and pour it into gutters that convey it under the 

 beaters, which are thus abundantly watered. 



Cotton and cotton cloth require in -particular this prepara- 

 tion ; otlierwife the ley could not penetrate to the infide of 

 the cotton, on account of the extracto-refinous matter con- 

 tained in it, as we have already obferved in fpeaking of that 

 fub fiance. 



In feveral manufactories a ley of foap is ufed : but all this 

 comes to the fame thing; that is to fay, the combination of 

 the oily matters with the alkali, in order to render them fo- 

 luble in water, and then to the combination formed between 

 a part of the colouring matter and that faline fubflance ; an 

 union moil eilential for bleaching. It is in thefe leys, there- 

 fore, and in rinfing in running water, followed by preifing or 

 wringing, to free the cotton from all fihh, that the prepara- 

 tions which precede immerfion in the oxygenated muriatic 

 acid con fifl. 



The apparatus mufl be arranged according to the objects 

 to be bleached : the fkains of thread mufl be fufpended in 

 the tub deflined for them, and the cloth mufl be rolled upon 

 ivels in the apparatus. When every thing is thqs difpofe<i, 



JU the 



