446 
Copperas 
“ deep, and two or three in diameter, are sunk where the 
“ gutters terminate. Upon this surface the brasses are 
“ laid to the thickness of 4 or 5 feet. The vitriolization 
“ shews itself in a white efflorescence, which is washed 
“ off by the rain into the gutters and conveyed by 
“ pipes from the wells to a reservoir, from which there 
“is a pipe of communication to the boiler. This is 
“ a leaden vessel generally about 7 feet deep, 12 to 
“ fourteen long, and 6 or 7 wide, where the liquor is eva~ 
“ porated for 6 days, during which time a quantity of old 
“ iron is added to it, as much as it will dissolve. It is then 
“ run into a crystallizing vessel, and remains there for 
tc five weeks, at the end of which time the mother liquor 
“ is run into a reservoir, and pumped back into the boil- 
“ er, and the crystals are removed, and after being well 
{< drained are packed in hogsheads for sale. A single 
“ boiling from a boiler of the above dimensions yields 
“ from 5 to 8 tons of copperas, according to the strength 
u of the liquor.” 
Vitriol is made near Haguenau on the Rhine nearly in 
the same manner, according to the description given by 
Cavillier. The pyrites is disposed on an inclined soil 
in beds about two feet thick, beneath which are gutters 
going to a common reservoir. The vitriolization of py- 
rites is always seen by whitish efflorescences tasting strong- 
ly Gf vitriol, at the same time that the surface of the py- 
rites cracks in every direction. When the season is dry it 
is occasionally watered to carry off the vitriol already form- 
ed, and to promote a fresh vitriolization in the remaining 
ore. The heaps are found to be exhausted when these 
saline efflorescences are but scanty, and when the lump 
when broken appears changed throughout into the liver 
pyrites . 
The vitriolic liquor is evaporated as usual in lead boil- 
ers, but it does not appear that old iron is regularly added 
