the oxygenated muriatic Avid. 295 
pieces were, therefore, only partially bleached, being white 
in fome parts and more or lefs coloured in others. Various 
other contrivances were tried without fuccefs, till it was dif- 
covered that an addition of alkali to the liquor deprived it of 
its fuffocating effects, without deftroying its bleaching pow 
ers. The procefs began then to be carried on in open vel- 
fels, and has been continued in this manner to the prefent 
period. The bleacher is now able to work his pieces in the 
liquor, and to expofe every: part of them to its action, with- 
out inconvenience. This advantage is unqueftionably great 5, 
but it is diminifhed by the heavy expence of the alkali, 
which is entirely loft. It is moreover to be feared, that the 
alkali which is added to the liquor, though it does not deftroy 
its power of bleaching, may diminifh it; becaufe a folution 
of the oxygenated muriat of potafh, which differs from the 
alkaline bleaching liquor in nothing but in the proportion 
of alkali, will not bleach at all. This is a well known fact, 
from which we might infer, that the oxygenated muriatic 
acid will lofe its power of deftroying the colouring matter of 
. vegetable fubftances, in proportion as it becomes neutralized 
by an alkali. But as we fhould not content ourfelves with 
inferences however plaufible, when the truth may be efta- 
blifhed by experiment; and as I thought the matter of fuf- 
ficient importance, I made the following experiments on the 
fubjec. 
I beg leave to premife, that in all thefe experiments I 
made ufe of one and the fame acid, which was kept ma 
bottle with a ground-glafs ftopper, and fecured from the in- 
fluence of light.» The ‘manner in which I made the experi- 
ments was fimply this. I weighed, firft of all, a bottle 
filled with the colouring fubftance which I meant to ‘em- 
ploy: I then weighed, in a large and perfectly colourlefs 
bottle, half an ounce of the acid, to which I immediately, 
butwery gradually, added of the colouring fubftance con- 
tained in the former bottle, till the acid ceafed to deftroy any 
more of its colour, ‘The bottle with the colouring fubftance 
U4 ae was 
