apc tela 
Ty. Gi f. “ene s Procefs for Seaeeaae Prints, per 
. Books, and other Articles of Paper. : 
este immerfion in oxygenated muriatic acid, fetting 
the articfe remain in it a longer or fhorter fpace of time, ac- 
cording to the ftrength of the liquid, will be fufficient to 
whiten an engraving. Ifit be required to whiten the paper 
of a bound book, as it is neceffary that all the leaves fhould 
‘be moiftened by the acid, care muft be taken to open the 
book well, and to make the boards reft on the edge of the 
veffel, in fach a manner that the paper alone be dipped in 
the liquid: the leaves muft be feparated from each other, in 
arder that they be equally moiftened on both fides. 
The liquor affumes a yellow tint, and the paper becomes 
white in the fame proportion. At the end of two or three 
hours the book may be taken from the acid liquor and 
plunged into pure water, with the fame care and precaution 
_as recommended in regard to the acid liquor, that the water 
may exactly touch the two furfaces of eacly leaf. The water: 
muft be renewed every hour to extract the acid remaining im 
the paper,’ and to diffipate the difagreeable fmell. 
By followimg this procefs, there is fome danger that the 
pages will not be all equally whitened, either becaufe the 
eaves have not been fufficiently feparated, or becaufe the 
Hquid has had more a¢tion on the front margins thart on 
thofe near the binding. On this account the practice fol- 
lowed by book-binders, when they wifh to whiten printed 
paper, is to be preferred. They deftroy the binding entirely, 
that they may give to each leaf an eyual and perfect immer- 
fion; and this is the fecond procefs recommended by M. 
Chaptal. 
«They begin,” fays he, “ by unfewing the book and fe- 
parating it into leaves, which they place in cafes formed in 
a leaden tub, with very thin flips of wood or glafs, fo that 
the leaves when laid flat are feparated from each other by in- 
tervals 
