A Dictionary of Arts (supplement): Bleaching of Paper.

(A Dictionary of Arts, Manufactures, and Mines; containing A Clear Exposition of Their Principles and Practice)
Recent improvements in
Arts, Manufactures, and Mines:
Being A supplement to his Dictionary
by Andrew Ure, M. D.,
F.R.S. N.G.S. M.A.S. LOND.; M. ACAD. N.S. PHILAD.; S. PH. SOC.N. GERM. HANOV.; MUHL. ETC., ETC.

Illustrated with one hundred and ninety engravings.

New York: D. Appleton & Company, 200 Broadway.  Philadelphia: George S. Appleton, 148 Chestnut St.
MDCCCXLVII
1847
BLEACHING OF PAPER. The following are the proportions of liquid chloride of lime, at 10° of Gay Lussac's Chlorometre, employed for the different sorts of rags, consisting of two piles, of 200 pounds French.

Cotton | litres.
No. 1. Fine cotton rags | 10
2. Clean calicoes | 12
3. - | 14
4. White dirty calico, coarse cotton | 16
5. Coarse cotton  | 18
6. Grey, No. 1  | 20
- No. 2 | 22
Saxon gray | 24
- No. 2 | 26
Palce white and half-white shades  | 28
Saxon blues; pale pink, dark blue, velvet | 32

It is considered to be much better to bleach the fine rags with liquid chloride of lime, and not with chlorine gas, because they are less injured by the former, and afford a paper of more nerve, less apt to break, and more easily sized. But the coarse or gray rags are much more economically bleached with the gaseous chlorine, without any risk of weakening the fibre too much. Bleaching by the gas is performed always upon the sorted rags, which have been boiled in alkaline ley, and torn into the fibrous state. They are subjected to the press, in order to form them into damp cakes, which are broken in pieces and placed in large rectangular wooden cisterns. The chlorine gas in introduced by tubes in the lid of the cistern, which falls down by its superior gravity, acting always more strongly upon the rags at the bottom than those above.

When the chlorine, disengaged from 150 kilogrammes (330 lbs.) of manganese and 500 kilos. of muriatic acid, is made to act upon 2,500 kilos. of the stuff (supposed dry), it will have completed its effect in the course of a few hours. The quantity of gaseous chlorine is equal to what is contained in the quantity of chloride of lime requisite to produce a like bleaching result. The bleached stuff should be forthwith carefully washed, to remove all the muriatic acid produced from the chlorine; for if any of this remain in the paper, it destroys lithographic stones, and weakens common ink.