— Procejs for whitening Paper. 23 
ities fearcely fenfible. The acid is then poured in, making 
it fall on the fides of the tub, in order that the Jeaves may 
not be deranged by its motion. When the workman judges, 
by the whitenefs of the paper, that it has been fufficiently 
aéted upon by the acid, it is drawn off by a cock at the bot- 
tom of the tub, and its place is fupplied by clear, freth 
water, which weakens and carries off the remains of the 
acid, as well as its ftrong fmell. The leaves are then to be 
dried, and, after being preffed, may be again bound up. 
“« The leaves may os placed alfo vertically in the tub; and 
this pofition feems to poffefs fome advantage, as cies will 
_then be lefs liable to be torn. With this view I confruéted 
_a wooden frame, which I adjufted to the proper height, ac- 
cording to the fize of the leaves which I wifhed to whiten. 
This frame fupported very thin flips of wood, leaving only 
the {pace of half a line between them. _ I placed two leaves 
in each of thefe interyals, and kept them fixed in their place 
by two {mall wooden wedges, which I pufhed in between 
the flips. When the paper was whitened I lifted up the 
frame with the leaves, and plunged them into cold water to 
remove the remains of the acid, as well as the fmell. This 
procefs I prefer to the other. 
“¢ By this operation books are not only cleaned, but the 
paper acquires a degree of whitenefs fuperior to what it poi- 
feffed when firft made. The ufe of this acid is attended alfo with 
the valuable advantage of deftroying ink fpots. This liquor 
has no action upon an of oil, or animal greafe; butit has 
_ been long known that a weak folution of potath will effeétu- 
ally remoye ftains of that kind. 
__ *‘ When I had to repair prints fo torn that they exhibited 
only {craps pafted upon other paper, I was afraid of lofing 
_thefe fragments in the liquid, becaufe the pafte became dif- 
folyed. In fuch cafes I enclofed the prints in a cylindric 
giafs veffel, which I inverted on the water in which I had 
. put the mixture proper for extricating the oxygenated muri- 
atic 
