i go B L E A C 
confiderable extent of premifes, ’being required for tbi-s 
purpofe. M.de-Croilille lias excluded the life of wood 
inevery part of his apparatus; and has applied the pro- 
cefs not only to bleaching, but-to the difeharging ol co¬ 
lours in dyed cottons or linens. 
M. Berlhollet further obferves, that the precaution of . 
plunging the cottons in pure water, after tIvey have been 
taken out of the acidulated water, is not fufficient ; but 
it is necelfary to plunge them into a weak cauftic lixivium, 
moderately heated, and keep them there for a fliort time. 
When the liquor is fuffered to run immediately into the 
troughs, care muff be taken to mix it well with the agi¬ 
tator ; becaufe otherwife, the mod fat urate d liquor, which 
occupies the lower part of the velfel, running firft, would 
exert too ftrong an action ; or if half or three quarters of 
the liquor be drawn olf, and mixed with the proper quan¬ 
tity of water, according to the precautions before eftab- 
lifhed, the reft of the fluid may be ufed together with the 
water for the fucceeding operation : laftiy, he obferves 
that this procefs, fimple as it is, can fcarcely be carried 
into execution, without, in the firft inftances, being di- 
redfed by a perl’on to whom the operations of chemiftry 
are familiar. He obferves, that a diminution, or even an 
equality, of the expences, relative to the ordinary procefs, 
is not to be hoped for, excepting for the bleaching of fine 
cloths, unlei's the operator pofTefTes a good procefs to ex¬ 
tract the foda from the reiidue of the diftillation ; and, 
without this condition, the bleaching of coarfer cloths 
ought not to be undertaken, excepting in thofe .cafes 
wherein the advantages arifing from the fpeed of the ope¬ 
ration, the facility of performing it in all places, and at 
all times, and.the diminution of the ftock or capital, are 
fufficient to compenfate for the excels of the price. Thefe 
obiervations are, perhaps, applicable to linens, and not 
cottons, it is not poffible, he continues to oblerve, to lay 
down principles applicable to.every particular cafe; but 
he advifes thofe who may undertake this objeft, to begin 
by trials, and by means of thofe trials to form calcula¬ 
tions, without any allowance on the favourable fide. On 
the other hand, lie advifes the operator not to fuffer him- 
felf to be impofed on by thofe Ioffes w hich arife for want 
of being familiarized with the operations; as there is no 
great expence incurred by making trials for a time, by 
which this .advantage is derived, that the operator renders 
hi.mfelf more expert for carrying more extenfive procefles 
into, efredt. 
M. Chaptal, of the royal fociety of Montpellier, after 
having tried thefe feveral experiments with precifion and 
fuccefs, prefented the following paper to the academy of 
Sciences at Paris. “ The property, which oxygenated 
muriatic acid pofteffes, of bleaching linen, cotton, &c. is 
a difeovery with which M. Berthollet has greatly enriched 
the arts ; but it appeared tome, that we might extend 
the application of it to other matters, and, in coifiequence 
of that idea, I have made Come experiments on the means 
of bleaching paper, of which the following are the refults. 
“ Blotting-paper, by being put into this acid, is bleach¬ 
ed .without flittering any injury ; and rags of coarfe bad 
cloth, fitch as are ufed in the paper-manufactories to 
make this kind of paper, may be bleached by this acid, 
and will then furnijh paper of a very fitperior quality. T 
bicached by it an hundred weight of pulp or pafle, in¬ 
tended to be made into blotting-paper, and the increafe 
of value in the prodiuT was computed at 25I. per cent, 
whereas the expence of the operation, when calculated in 
the ft riot eft manner, amounted only to 7I. per cent. The 
property poifelfed by this acid, of bleaching paper with¬ 
out injuring its texture, renders it .very valuable for re- 
itoring old books, and linoked prints. The latter, when 
difcoloured to fuch a degree that the fubjebt of them could 
hardly be diftinguifhed, were re-eftabli(lied and revived, in 
fo aftonifliing a manner that they appeared to be new ; and 
old books, foiled by that yellow tinge which time always 
.produces, may.be fo completely renewed, that one might 
Tup pole them tp be juft conic out of the prefis. The fimple 
H I N G. 
im'marfion of a print in oxygenated muriatic acid (leaving it 
therein a longer or a (hotter time, according to the ftrength 
of the liquor) is all that is required for bleaching it; but, 
when a book is to be bleached, forne farther precautions are 
to be ufed. As it is necefiary that the acid thould wet every 
one of the leaves, the book mud be completely fpread 
open, and then, by letting the boards of the binding reft 
upon the Tides of the veflel, the paper only will be immerfed 
in the liquor. If any of the leaves (tick together, they 
mud be carefully feparated, that all of them may be equal¬ 
ly impregnated. The liquor takes a yellow tinge, the pa¬ 
per grows white, and, after two or three hours, the book 
may be taken out of the liquor, and foaked in clean water, 
which thould be changed from time to time, in order to 
wadi out the acid with which the book is impregnated,- 
and alfo to deprive it of the difagreeable fmell it has 
contracted. 
“ The above method, which is the firft I made life of, 
has generally fucceeded pretty well ; too often, however, 
tlie leaves of my books have had a motley appearance, and 
fometimes feveral pages were not at ail bleached ; I was, 
therefore, obliged to have recourfe to the following more 
certain procefs. I began by unfevving the books, and re¬ 
ducing them into Iheets ; thefe fheets I placed indivifions 
made in a leaden velfel, by means of thin flips of wood, 
fo tliat the leaves, when laid fiat, were feparated from 
each other by very frnall intervals. I then put the acid 
into the velfel, pouring it againft the lide, that the leaves 
might not be difturbed ; and, when the operation was 
finilhed, I drew off the acid, by means of a cock fixed 
in the bottom of the veffel. I then filled the veflel with 
clean water, which w'alhed the leaves, and took off the 
fmell of the oxygenated acid. They may then be dried, 
fmoothed, and new bound. In this manner I have reftored 
many valuable books, whicli had become worthlefs from 
the bad ftate they were in. But, inftead of the method 
above deferibed, the leaves may be placed vertically in 
the velfel, and this pofition is attended with fome advan¬ 
tage, as they are lefs ealily torn, For this purpofe I have 
conftrufted a frame of wood, which I fix to the height I 
think moft convenient, according to that of the leaves I 
with to bleach. This frame fupports a number of very 
thin flips of wood, which leave between them only a fpace 
of about the twentieth of an inch ; I put two leaves in 
each of thefe fpaces, and I fix them by means of two finall 
wooden wedges, which I thruft in between the flips, and 
which prefs the leaves againft the flips. I have another 
reafon for preferring this method to the other, namely, 
that, when the operation is finiJhed, I can take out the- 
frame with the leaves in it, and plunge the whole together 
into clean water. By this operation the books are not 
merely reftored to their original ftate, but the paper ac¬ 
quires a degree of whitenefs it never before poifelfed. 
The acid has alfo the good eftert of intirely taking away- 
fpots of ink, by which books and prints are often much 
disfigured. This liquor, indeed, has no effeift upon fpots 
of oil, or other greafe ; but it has long been well known 
that a weak ioiution of cauftic alkali furnifhes a certain 
means of removing them. When I had to bleach prints, fo 
torn to pieces that they confided only of fragments fitted 
together, and pafted upon paper, I was afraid I might lofe 
fome of thefe fragments in the liquor, becaufe they fepa- 
rate from the paper by the foftening of the pafte ; in that 
cafe, therefore, 1 took the precaution of enclofing the 
print in a large cylindrical bottle, which I turned npfide- 
down, fixing its mouth to that of a velfel in which I had 
put a mixture proper for dilengaging oxygenated muria¬ 
tic gas ; this gas fills the infide of the bottle, and, acting 
upon the print, takes off the ftains, ink-fpots, &c. while 
the fragments remain palled to the paper, and confequently 
keep their refpective places.” 
From thefe difeoveries of the French chemifts, the in¬ 
genious amongft our own countrymen have, with laudable 
zeal and induftry, endeavoured to reduce their fpecula- 
tions to the beft,advantages in trade. The cotton-mamj- 
faiturersj 
