PAPER. 
to expofe every part of them to the aftion of the bleach¬ 
ing gas. 
After the procefs, which muft be concluded as foon as 
ever the rags are fufficiently bleached, left the gas ffiould 
aft upon and injure their quality, they are to be waftied 
in water, and will be ready for the mill. Some manu- 
fafturers think that this mode of bleaching the rags 
makes them rotten, and injures the quality of the paper ; 
which it certainly does if carried too far, though there 
is no doubt of the advantages of the procefs if well con- 
dufted. 
The bleaching-procefs has given rife to great complaints 
from the printers, as many printing-papers are now made 
from cotton-rags. The oxygenated muriatic acid, being 
applied for the purpofe of obtaining difpatch and deli¬ 
cacy of colour, produces a paper of a good appearance 
from an inferior ftaple. Nothing can be more perplexing to 
a printer, nor more detrimental to his labours, than this 
kind of bleached paper; for, although it may be thick, 
and feem ftrong in the ream, no fooner does the water 
penetrate through it, than it lofes its adhefive quality, 
and becomes fo loofe and foft as fcarcely to bear handling, 
and in working under the prefs finks down into the cavi¬ 
ties of the letters, leaving a part of its fubftance behind, 
after every impreffion, until it fo clogs the type that the 
work is rendered fcarcely legible. Nor is it lefs excep¬ 
tionable in point of durability, as it muft moulder away 
in a little time, with the common ufe that popular books 
generally undergo. Notwithftanding this, it muft be al¬ 
lowed, that if, by bleaching, the paper-makers can pro¬ 
duce a bad article from fuch materials as were otherwife 
of no ufe, they are alfo able to improve their manufafture 
when they ufe the fame materials as formerly. It is found 
moft advantageous to bleach the rags in the ftate of half- 
ftuff, that is, when they have been once worked by the 
mill, as, the fibres being by that means feparated, the 
gas has greater accefs to the interior parts, and they are 
bleached quicker, fo as to have lefs danger of injury to 
particular parts, by too long an aftion of the gas. Ano¬ 
ther method of bleaching, is by muriat of lime put into 
the waftiing-engine, which for printing-papers is that 
now moft commonly ufed. But Mr, Bigg’s procefs is in¬ 
tended to apply to the paper not only after it is made, 
but even after it is printed ; and it has the efreft alfo of 
reftoring damaged or mildewed printed paper, not only 
without injuring the type, but even greatly to improve 
the brilliancy of it. This has been given under the arti¬ 
cle Bleaching, vol. iii. p. 102. 
The rags are now ready to be thrown into the waftiing- 
engine of the paper-mill ; which brings us to the fecond 
and moft important operative feCtion. 
II. Formation of the Sheet in the Mill. —The en¬ 
gines now ufed in paper-mills are conftrufted on fuch a 
powerful principle, that they are capable of reducing the 
ftrongeft and tougheft rags to pulp in a moderate time ; 
whereas the old machines were not able to work the rags 
without fermenting, or rotting, them, as a previous pro¬ 
cefs. The following extrafts from a French work on the 
art of making paper, will ftiow the manner in which it 
was conducted fixty years ago. 
“ The rags, being forted, are put into a large ftone vat, 
fixteen feet long, ten broad, and three deep ; water is 
poured upon them at the top during ten days, and eight or 
ten times every day, without ftirring them. They are af¬ 
terwards left to reft the fame number of days, and fome- 
times more or lefs, without pouring water upon them. 
Then, being turned over, the centre is brought to the 
furface, to facilitate the fermentation ; and, after being 
turned again, they are ftill left fifteen or twenty days in 
fermentation, fo that the rotting may laft five or fix weeks ; 
the term is not fixed, but when the heat becomes fo great, 
that the hand, thruft in, cannot endure it above fome fe- 
conds, it is judged that it is time to ftop it. In mills 
which have but few rags to work upon, they are left to 
rot longer, becaufe the heaps, being fmaller, heat lefs, and 
307 
with more difficulty; fo that nothing can be juftly de¬ 
termined of the time proper for the rotting part. It de¬ 
pends alfo on the quality of the rags ; the fineft linen 
does not rot fo foon as the coarfe ; and linen that has 
been worn with more difficulty than new, becaufe the in¬ 
ternal humidity, that difpofes the fibres to fermentation, 
is more confiderable in new or coarfe than in fine or worn 
linen. Such as are more or lefs ftrong, more or lefs worn, 
refill the aftion of rotting in different degrees, fome be¬ 
ing fpoiled when others have not gone through the firft 
fermentation ; fo that the rags, which have been forted 
with great care, ought to be left to rot together, to avoid 
the rilk of altering the whole parcel, by the mixture of a 
portion of rags quite different from the reft. When cham¬ 
pignons grow on the heaps of rags, it is reckoned to be a 
fign of their being well rotted. 
“ Befides this, there is another method for difpofing of 
the rags in the place for rotting and fermenting them. 
Having been wetted with water, a heap is made of them 
in a corner of the vaulted room, which is deftined for 
that purpofe. They are watered from time to time, and, 
when fufficiently heated, are tranfported into another an¬ 
gle of the fame room, fo that what was at the top of the 
firft heap is now laid under the fecond ; and care is taken 
to throw water upon them from time to time. When this 
heap takes heat again, it is tranfported to the third corner, 
where, having fermented again, it is carried into the 
fourth angle ; obferving always to lay thofe rags under 
the heap that were at the top of the foregoing, and to 
water them often ; for a reddifh water will come from 
them, which it is very neceflary to clear the rags of. 
When the heap in the firft corner is brought away, ano¬ 
ther is formed in the fame corner, which paffes in its turn 
to the feveral corners of the room. 
“ Some, to accelerate the operation of rotting and fer¬ 
menting, throw lime upon the rags. Perhaps a very fmall 
quantity of lime may be ufed ; but, if too much is laid on, 
the corroded rags will be too foon reduced into a pulp, 
and will pafs through the ftrainer with the water, which 
ought to carry off only their filth, and will occalion a 
confiderable wafte. The ufe of lime, for the purpofe of 
rotting rags, is abfolutely prohibited in France.” 
The aftion of rotting was, at that period, thought ne- 
ceffary for abridging the labour of making paper, and fa¬ 
cilitating the operation of the.mill; but feveral advantages 
are procured by difpenfing with it, now we are able to 
deftroy the texture of the cloth, and reduce it to pulp, 
without previoufly corrupting its fubftance by rottingit; 
the paper is much ftouter, is lefs liable to break, and is 
alfo whiter; for the fermentation gave ayellowifti hue to 
the furface of the rags, which the mill could not take out 
without difficulty, and never could entirely, if the rags 
were too rotten. 
We now come to defcribe the ftrufture of paper-mills. 
In England they work with cylinders, or engines, an in¬ 
vention which was brought from Holland many years ago, 
and found to be fo great an improvement, that it has been 
univerfally adopted. The old mills, which are ftill in ufe 
in fome parts of the continent, aftuate a number of Hamp¬ 
ers, or peftles, which pound the -rags in wooden mortars 
till they are reduced to a pulp. Thefe mortars are cut 
out in a block of heart of oak, well feafoned, the cavity 
being of an oval figure, about eighteen inches broad, 
thirty inches long, and eighteen or twenty in depth ; the 
bottom concave, and lined with an iron plate an inch 
thick, eight inches broad, and thirty long, ftiaped inwards 
like a mould for a falmon, with the head and tail rounded. 
In the middle of the mortar is a cavity beneath the plate, 
and four or five grooves are cut, forming channels which 
lead to a hole cut from the bottom of the cavity quite 
through the block : it is covered by a piece of hair-iieve 
fattened on the infide. This plate is grooved to make 
teeth, on which the teeth of the hammers aft, to cut the 
rags in pieces. The ufe of the hair-fieve is to prevent any 
thing from going out but foul water. Two hammers, or 
peftles. 
