BLEACHING. 165 



apparatus by Mr. Rupp of Manchester, which is 

 described in .the Manchester Memoirs. Still it 

 was found that the acid alone was apt to weaken 

 the cloth, and that it injured the health of the 

 workmen. 



At length it was discovered by some manufac- 

 turers at Javelle, near Paris, that the addition of 

 an alkali to the liquor deprived it of its suffocating 

 effects, without destroying its bleaching powers. 

 Potash was the alcali they employed ; and this so- 

 lution was called the Javelle liquor. The invent- 

 ors came into this country, and established a 

 bleaching-work. The process was then carried on 

 in open vessels ; and the bleacher was able to work 

 his pieces in the liquid, and expose every part to 

 its action without inconvenience. 



Although these advantages were unquestionably 

 great, they were diminished by the heavy expense 

 of the alcali, which was entirely lost. Also, the 

 the potash, which added to the liquor, though it did 

 not destroy its power of bleaching, diminished it ; 

 because a solution of the oxygenated muriate of 

 potash, which differs from this bleaching-liquor in 

 nothing but in the proportion of alcali, will not 

 bleach at all. This is a well-known fact; from 

 which we might infer, that the oxygenated muri- 

 atic acid will lose its power of destroying the co- 

 louring-matter of vegetable substances, in propor- 

 tion as it becomes neutralized. 



Mr. Tennant discovered that lime might be 

 substituted for the potash, the oxymuriatic acid 

 combining with all the alcaline earths, and forming 

 oxymuriates which were soluble in water, and had 

 the property of bleaching. This is the substance 

 now employed. If the oxygenated muriatic acid 

 be passed through lime-water, it will combine with 



M 3 



