9$ B L E A C 
they arc carried to the whiffter, or bleacher, who puts them 
directly into wooden troughs, full of cold clear water ; 
where with wooden mallets, w hich are moved by a water, 
mill, they are io well agitated and beaten, that they are 
infallibly cleared from all their impurities, Being ta¬ 
ken out of the mill, they are Ipread on a meadow, where 
the dew w hich they receive during a week begins to bleach 
them. Then they are put into tubs, and they throw over 
them a common lye, quite hot. The linens having thus 
gone through the lye, they take them out of the tub, to 
clean them again in the mill ; then they fpread them a 
fecond time in the meadow, where they leave them a week, 
after which they give them a fecond lye : all thefe feveral 
operations are repeated until the linens have acquired a per¬ 
fect degree of whitenefs. Then they fold them up, in 
a manner proper to each fort, and to the places for which 
they are defigned. 
With refpeCl to the new improvements in the art of 
bleaching, recently difeovered by the French chemids, it 
appears that filk may be cleared of its impurities to better 
advantage by the mild alkali of foda, than by foap-lees, 
or foap; the former of which is apt to injure its texture, 
and the latter is expenlive. It is even aflerted that mere 
water will accompiilh the fame, efpecially if its vapour 
be confined, when heated in a veffel, upon the principle 
of Papin’s Digefler. A procefs of this nature, however, 
muff require peculiar management; becaufe the water thus 
confined would doubtlefs be as adlive in dilfolving the filk 
itfelf, as eaudic alkali might be. The remedy or precau¬ 
tion will confid in fufFering the fleam to efcape through an 
aperture, covered by a valve, loaded with no greater 
weight than experiment (hall (hew to be fufficient for the 
intended purpofe. The dephlogidicated or aerated marine 
acid, fird difeovered by Scheele, is now applied to the art 
of bleaching linens and cottons. Several chemifls of the 
tin! eminence have attended to the properties of this fub- 
ifance. M. Berthollet lias given a defeription of this me¬ 
thod of bleaching in the fecond volume of the Annals of 
Cliemidry, of which the following is an abridgement. 
The fird objeft which this philofopher propofed, was 
to examine the folubility in water of the oxygenated mu¬ 
riatic acid gas, according to the New Nomenclature (fee 
Chemistry) ; becaufe he naturally imagined that, if he 
could obtain a folulion fomewhat concentrated, it would 
be much eafier to make experiments with this liquor, than 
wiih the fame fubfiance in the gafeous form. He foon 
perceived that the gas was dilfolved in water more readily 
and in a much larger quantity, than the carbonic acid gas, 
or fixed air ; and that the water, upon faturation with it, 
acquired a very lively fmell, a yellowilh colour, and pe¬ 
culiar characters. Thefe firft experiments were made by 
agitating the water in contad with this gas, in the fame 
manner as that fluid is ufual'ly impregnated with the car¬ 
bonic acid gas; but the biffbeating vapour which was e- 
jnitted, led him to fubditute the apparatus of Mr. Woulfe 
anfiead of that he had before ufed. Between the retort, 
and the bottles filled with water for the purpofe of impreg¬ 
nation with this gas, he placed a fmall bottle furrounded 
with ice, to retain the muriatic vapour which was not oxy¬ 
genated. The bottles filled with water were likewife fur- 
rounded with ice. He obferved, in this operation, that, 
■when the water became faturated with the gas, the gas it- 
lelf affumed a concrete form, and was llowly precipitated 
to the bottom. 
If a body with a recurved tube be filled with this water, 
impregnated with the dephlogidicated or oxygenated mu¬ 
riatic acid, and the outer extremity of the tube be ini- 
ineri’ed under a receiver filled with water; if, in this fitu- 
at'on, the fluid be expofed to the light of the fun, bub¬ 
bles are foon difengaged, which pafs into the receiver, 
and are found to confid of pure or vital air. When the 
bubbles have ceafcd to be difengaged, the liquor is found 
to have lofl its charaCleriftic fmell, colour, and all itsdif- 
tindive properties ; and is found to confifl of mere water, 
containing a proportion of common muriatic acid. This 
H I N G. 
Ample experiment, M. Berthollet obferves, ought to be 
fufficient to afford a conviction, that the oxygenated mu¬ 
riatic acid is really nothing but a combination of the mu. 
riatic acid with a bads of vital air, or oxygene, which is 
found fo abundantly in the black oxyde or calx of manga, 
nefe, that nothing more is necelfary than to urge this 
oxyde by a (hong heat, in order to obtain a large quan¬ 
tity. Manganefe, tints treated, is no longer proper to 
form the oxygenated muriatic acid; becaufe it is deprived 
of that portion of oxygene which is required to combine 
with part of the muriatic acid. lie remarks, that light 
pofTeffes tlie property of difengaging the oxygene which 
was combined with the muriatic acid, by reftoring that 
elaflicity of which it was partly deprived ; a refloration 
not to be effected by mere heat: he concludes therefore 
that the light combines with the oxygene, and that the 
elaflic (late of vital air is owing to this combination; which 
air, by lofing a fecond time its elaflicity in the procefs of 
combuftion, that is to fay, by a rapid combination with 
fome other body, again fullers.the principle of light to 
efcape, at the fame time that much heat is difengaged ; 
the relation of which lad fubfiance with light is flill an 
objeft for future difeovery. 
If vegetable colours be plunged in the oxygenated mu¬ 
riatic acid, they difappear more or lefs fpeedily, and more 
or lefs perfectly. When the fubfiance under examination 
poffeffes a mixture of different colouring parts, fome dif¬ 
appear more readily, and leave only thole which more ef¬ 
fectually refift the power of this agent, but have never- 
thelefs differed a confiderable alteration. The yellow co¬ 
louring matters ufually refift the mod drongly, but at 
length they all difappear; and when the oxygenated mu¬ 
riatic acid has exerted its whole adion, it is found to be 
reduced to the date of ordinary muriatic acid. Hence it 
follows, that the colouring matters have deprived it of 
the oxygene or vital air ; and have, by this combination, 
acquired new properties, at the fame time that they have 
loft that of producing colours. This ingenious chemifl 
declinesentering, in this memoir, into the properties of 
thefe oxygenated fubdances ; and proceeds to obferve, 
that the oxygenated muriatic acid owes its property of de- 
droying colours to the oxygene, which not only is com¬ 
bined abundantly with it. but likewife adheres with very 
little force ; and readily paffes into a date of combination 
with fuel) fubdances as have a certain degree of affinity 
with it. The habitudes of fuel) a variety of colouring 
matters as exih in nature, with the oxygene, with light, 
with alkalis, and with other chemical agents, cannot but 
form an highly intereding, and almod entirely unexplor¬ 
ed, part of natural philofophy. 
After having obferved the adion which the oxygenated 
muriatic acid exercifes in general upon colouring matter, 
he concluded that it might produce the fame effed upon 
thofe fubdances which colour thread and linen, and which 
the art of bleaching propofes to dedroy. Without confin- 
ing himfelf to deferibe the procefs as now pradifed, he 
enters into a concife detail of the imperfect efl'ays he made 
at firft: a detail which is by no means without great uti¬ 
lity to fuel) as are defirous of carrying the procefs into 
execution ; and therefore we diall date it here. He at 
fird ufed a very concentrated liquor, which he renewed 
when exhauded, until the thread or cloth appeared diffi¬ 
dently white : but, in this way, he foon perceived that 
their texture was condderably weakened, and that they 
were eve,n deprived of their folidity. He therefore flight- 
ly diluted the liquor, and fucceeded in bleaching his cloth, 
without altering it ; but it foon became yellow by keep¬ 
ing, and more efpecially when it was heated, or fubjected 
to the aiStion of an alkaline lixivium. He then directed 
his reflections to the circumftances of the udial procefs of 
bleaching, which he endeavoured to imitate ; becaufe lie 
had adopted the opinion, that the oxygenated muriatic 
acid ought to ad in the fame manner as the expofure of 
cloth upon bleach-grounds ; which expofure alone is not 
fufficient for the purpofe, but appears merely to difpofe 
