294 On the Procefs of Bleaching with 
many ways, but particularly i in the quick circulation of their 
capitals. ; ' : 
Great difficulties, for a time, impeded its progrefs, atifiig 
chiefly from prejudice and the ignorance of bleachers in che- 
mical proceflés. Thefe obftacles were, however,  foon re- 
moved, by Mr: Watt at Glafgow, and by Mr..Henry:and 
Mr. Cooper at Manchefter. Another difficulty prefented it- 
felf; which had nearly proved fatal to the fuccefs of the ope- 
ration. This was the want of a proper apparatus, not for 
making the acid and combining it with water, for this had 
been fupplied in a very ingenious manner by Mr. Watt and 
M. Berthollet*; but for the purpofe of immerfing and 
bleaching goods in the liquor. The volatility of this acid 
and its (ogapeaiies yapours prevented its application in the 
way commonly ufed in dye-houfes. Large cifterns. were 
therefore conftructed, in which pieces of {tuff were ftratified ; 
and the liquor. being poured on them, the cjfterns were 
clofed with lids. But this method was foon found to be de- 
fective, as the liquor could not be equally diffufed ;. the 
* M. Berthollet’s apparatus, however, is too contplex for the ufe ofa 
manufaétory; Mr. Watt’s is better; but a'range of four, five, or fix 
hogfheads, or rum-puncheons, conneéted with one another, in the man- 
ner of Woulte’s diftilling apparatus, is preferable ro-either of them. Agi- 
tators, on M. Berthollet’s princip!e, may be applied. The retort or ma- 
trafs fhould be of lead, flanding in a water-bath ; its neck fhould he of 
fufficient length to condenfe the common muriatic acid, which always 
comes over, and it fhould form an incliaation towards the body of the re- 
tort, fo that the candenfed acid may return ito ir. _ I beg leave to obferve 
here, that I always found the liquor to be ftrongeft when the diftillation 
was carried on very flowly. I have alfo found, that the ftrength of the 
liquor is much increafed by diluting the vitriolic acid more than is ufually 
done. The following proportions afforded the ftrongeft liquor : 
Three parts manganefe. 
Bight parts common fale. 
Six parts oil af vitriol, 
Twelve parts water. 
The proportion of manganefe is fubject to variation according to its qua- 
Sty. 
Saedee pieces 
