BLEACHING. 177 



" By this operation, books are not only cleaned, 

 but the paper acquires a degree of whiteness su- 

 perior to what is possessed when first made. 



" The use of this acid is attended also with the 

 valuable advantage of destroying ink-spots. This 

 liquor has no action upon spots of oil or animal 

 grease ; but it has been long known that a weak 

 solution of potash will effectually remove stains of 

 that kind. 



" When I had to repair prints so torn that they 

 exhibited only scraps pasted upon other paper, I was 

 afraid of losing these fragments in the liquid, be- 

 cause the paste became dissolved. In such cases, 

 I enclosed the prints in a cylindric glass vessel, 

 which I in verted, on the water in which I had put 

 the mixture proper for extricating the oxygenated 

 muriatic acid gas. This vapour, by filling the 

 whole inside of the jar, acted upon the print, ex- 

 tracted the grease as well as ink-spots, and the 

 fragments remained pasted to the paper." 



Bleaching of Paper. 



The oxygenated muriatic acid has also been ap- 

 plied to the bleaching of paper, which it has ren- 

 dered considerably more expeditious. 



Bleaching of old printed papers to be worked up 

 again. Boil the paper for an instant in a solution 

 of soda, rendered caustic by potash. Steep it in 

 soap water, and then wash it, after which the pa- 

 per may be reduced to a pulp by the paper-mill. 



Bleaching of old written papers to be 'worked 

 again. Steep the papers in a cold solution of sul- 

 phuric acid in water, after which wash them before 

 they are taken to the mill. If the acidulated wa- 

 ter be heated, it will be the more effectual. 



VOL. II. N 



