B L E A C H I N G. 
-the colouring matter to folution in the alkali of lixiviuuis. 
Me examined the dew which is precipitated from the at- 
■mofphere, and likewife that which is afforded by the noc¬ 
turnal tranfpiration of plants ; and obferved that both 
the one and the other were faturated with oxygene to inch 
a degree, as to deflroy the colour of paper weakly tinned 
with turnfole ; and he remarks that the ancient prejudices 
refpe&ing May dew, which is the feafon wherein th.e tran- 
fpiration of plants is abundant, might probably depend 
on fome obfervation of this nature. He therefore em¬ 
ployed, alternately, the lixiviums, and the action of the 
oxygenated muriatic acid ; by which means he obtained a 
permanent white. And as it is the practice, in the ordi¬ 
nary way of bleaching,-to pafs the cloth through lour 
milk, or vitriolic acid diluted with a large quantity of wa¬ 
ter, he made the trial likewife of palling his cloths through 
a very diluted folution of vitriolic acid, and obferved that 
the white became much brighter. 
As foon as he had made ufe of the intermediate lixi¬ 
viums, he found that it was not necelfary to ufe a concen¬ 
trated liquor, or to leave the cloth long in the fluid at 
each immerlion. By this obfervation he avoided two in- 
.conveniencies, which might have rendered the procefs im- 
prafticable in the large way ; the firll is, the fuffocating 
Irnell of the fluid, which would be very incommodious, 
and even highly dangerous, to be refpired fora long time, 
and which has difcouraged feveral operators from purfuing 
their attempts j the fecond is the danger of weakening the 
cloth. At this period of his experiments he likewife gave 
up the idea of mixing alkali with the oxygenated muriatic 
.acid as he had before done in mod of his experiments. 
This was the ftate of the experiments of this excellent 
chemift, when he repeated them in the p re fence of the ce¬ 
lebrated Mr. Watt. A Angle glance, he obferves, is fuf- 
ficient to a philofopher whofe abilities had been fo long 
exetcifed upon the arts, Mr. Watt loon afterwards w'rote 
to him from England, that in his firll operation he had 
bleached five hundred pieces of cloth on the premifes of 
Mr. Grigor, who has large bleach-grounds at Glafgow, 
and continues to ufe this new procefs. 
In the mean time M. Bonjour, who had a (lifted M. 
Berthollet in his experiments, and who to a large ftiare of 
fagacity has added a very extenlive knowledge in chernif- 
try, entered into an agreement with M. Conllant of Va¬ 
lenciennes to form an eftablifhment in that town. This 
project was oppoled by the prejudices and intereft of the 
bleachers, who were apprehenfive of the competition of a 
new method. M. Conllant could not even procure a piece 
of ground in the town of Valenciennes : but the count de 
Belainge favoured this enterprife, and gave up a pafture 
which poflefied every advantage ; but, being remote from 
Valenciennes, would have the difadvantage of diltance, if 
any manufactory fliould be eftablifhed at Valenciennes it- 
fielf. M. Bonjour had given up the well-grounded hopes 
which his knowledge and talents gave him reafon to expert 
at.Paris; and had in return found, in the enterprife to 
which he had devoted his attention, nothing but thole dif- 
gufting circumftances which ufually accompany new pre¬ 
cedes in-the arts. He addrefied himfelf to the bureau de 
commerce, not to reward his fervices, but to requeft that 
lie might be defended from the difadvanta-ges and obfta- 
cles which prejudice and an oppolition of intereft had cre¬ 
ated in Valenciennes, by granting to him a certain fpace 
of two leagues round Valenciennes and Cambray, in which 
he alone might, during a certain number of years, exer- 
cife this new art; without c.onllraining in any refpert thofe 
who might choofe to adhere to the ancient precedes, or 
attempt new precedes, in which no ufe lliould be made of 
the oxygenated muriatic acid. He offered to inftruCt in 
his manufactory, in all the details of his procefs, all ftich 
as might be delirous of tiling it, and might obtain the fanc- 
tion of the government It is probable that, if this re- 
.quell had been granted, the eftablifhment at Valenciennes 
.might have produced a greater degree of confidence in 
ithofe who had undertaken to mak? the neceflaiy advances., 
Vol. III. No. i it}. 
It is probable, continues M. Berthollet, that they might 
have Ihortened their trials, inllead of ellablilhing the pro¬ 
cefs at Courtray, as they have done ; many artifts might 
probably have been formed under the direction of M. Bon¬ 
jour ; and a great number of eftablifhments- might have 
been formed.in the French provinces, by avoiding thofe 
fruitlefs trials which tend to throw difcredit upon an ufe- 
ful art. 
As foon as M. Berthollet had reafon to hope that the 
procefs might be executed in the large way, he endeavour¬ 
ed to diminifh the price of the liquor, by decompofing the 
marine fait in the very operation which ferved to form it. 
His firll trials were unfuccefsful; but M. Welter, a young 
and ingenious cheinift to whom M. Berthollet had entruft- 
ed the management of the procefs, obferved that it might 
be of advantage to dilute the vitriolic acid ; and the ope¬ 
ration then fucceeded in the, moll fatisfaclory manner. He 
immediately wrote'to M. Bonjour and Mr. Watt, the latter 
of whom informed him that he had made this change from 
the firll; and the operation was afterwards defcribed by 
M. Chaptal, in a Memoir forwarded by him to the Aca.- 
demy of Sciences.' Mr. Watt had likewife made ufe of a 
certain C3.lk or butt, of a conftruCtion which M. Berthol¬ 
let was not acquainted with ; but, before this apparatus 
was mentioned, M. Welter had conltruCted one, which 
is not only proper to prepare the oxygenated muriatic acid,, 
but very well calculated for other chemical operations. 
The intention of this apparatus, which is fhewn in the an¬ 
nexed plate, is to multiply the furfaces of contact be¬ 
tween the gas and the water,, as it is evident that the com¬ 
bination can take place only at their furfaces. That part 
of the gas which did not enter into combination in the 
lower fpace, where it is firll conveyed, pafles into a fecond 
cavity or fpace which is above the tube intended to give 
it vent. The veflel which is. intermediate between the 
pneumatic tub or calk, and the diftillatory mattrafs, is 
defigned to retain that part of the muriatic acid which is 
not oxygenated : a fmall quantity of water is put into this 
veflel, a glafs tube being plunged therein, the height of 
which exceeds that of the column of water the gas mult 
overcome in the calk. The gas which pafles out of the 
mattrafs comprefles the water in the intermediate veflel 
with a force equal to that oppofed to its difengagement; 
fo that the water rifes in the tube of fafety, and forms a 
column equal to the weight of the water which prefles 
on the tube through which the gas enters the calk. 
But if, during the operation, a fudden cooling or rapicj. 
abforption of gas fliould take place, the water defcends 
again in the tube, the air of the atmofphere enters, and 
prevents a vacuum from being formed within, which 
would have been attended with a reforption of the liquor, 
and confequently break the diftilling veflel by the hidden 
cooling. This tube of fafety, which is due to the ingenious 
M. Welter, and the celebrated Chaptal, is equally appli¬ 
cable to other pneumatic diftillations. 
If the oxyde or calx of manganefe be of a good kind, 
in fmall cryftals, and contain very little foreign matter, 
the proportions which M. Berthollet found bell calculated 
for diftillation are the following : Six ounces of pulve¬ 
rized calx of manganefe, one pound of pulverized fea- 
falt, twelve ounces of concentrated vitriolic acid, and 
from eight to twelve ounces of water. If the calx of man- 
ganefe contain foreign earth or metallic fubftances, the 
quantity mull be augmented in proportion to its impurity. 
It will be known, after the operation, whether a fufficient 
quantity has been employed; becaufe a fmall quantity 
ought to remain undecoryipofed, and of its original black 
colour : from this obfervation, 'the quantity proper to be 
ufed in the following operations may be afcertained. When 
the calx of manganefe is found to contain calcareous fpar, 
as may be known by its effervefcing upon the contart of a 
fmall quantity of vitriolic acid, it is proper to wafti it be¬ 
fore the operation with diluted vitriolic acid, to feparat9 
the calcareous part, which might be troublefome on ac¬ 
count of the elfcrvelceticc it produces; the calx mull be 
C c dried 
