DOI Page / Citation link:
https://doi.org/10.11588/diglit.19571#0075
THE ARTIST'S ASSISTANT. 61
" filter mav be then thrown away. In the mean
" time, dffiblve of clean alum four pounds, and of
" green vitriol or copperas two pounds, in three gal-
" Ions of water. Add this folution gradually to the
" filtered lixivium, fo long as any effervefcence
" appear to arife on the mixture ; but, when no
" ebullition or ferment follows the admixture, ceafe
" to put in more. Let the mixture then fland at
': reft, and a green powder will be precipitated:
'; from which, when it has thoroughly fubfided, the
t: clear part of the fluid mult be poured off, and
<; frefh water put in its place, and ftirred well about
" with the green powder ; and, after a proper time
£; of fettling, this water muft be poured off like the
£; firft. Take then ~ of fpirit of fait double the
'; weight of the green vitriol which was contained
'; in the quantity of folution of vitriol and alum,
t: added to the lixivium, which will foon turn the
c: green matter to a blue colour ; and, after fome
<; time, add a proper quantity of water, and wafh
w the colour in the fame manner, as has been di-
t; reeled for lake, &c. and, when properly wafhed,
': proceed in the fame manner to dry it in lumps of
11 convenient fize."
The brightnefs, deepnefs, and coolnefs of Pruffian
blue, are proofs of its goodnels — for with thefe qua-
lities it may be depended upon in ftanding well.
Sophiftication, or any thing amifs in the procefs,
may be feen by its being more foul and purple.
V E R D I T E R,
Is formed by adding a due proportion of chalk to
a folution of copper, made by refiners in precipi-
tating the filver from the aquafortis, in the opera-
ration
" filter mav be then thrown away. In the mean
" time, dffiblve of clean alum four pounds, and of
" green vitriol or copperas two pounds, in three gal-
" Ions of water. Add this folution gradually to the
" filtered lixivium, fo long as any effervefcence
" appear to arife on the mixture ; but, when no
" ebullition or ferment follows the admixture, ceafe
" to put in more. Let the mixture then fland at
': reft, and a green powder will be precipitated:
'; from which, when it has thoroughly fubfided, the
t: clear part of the fluid mult be poured off, and
<; frefh water put in its place, and ftirred well about
" with the green powder ; and, after a proper time
£; of fettling, this water muft be poured off like the
£; firft. Take then ~ of fpirit of fait double the
'; weight of the green vitriol which was contained
'; in the quantity of folution of vitriol and alum,
t: added to the lixivium, which will foon turn the
c: green matter to a blue colour ; and, after fome
<; time, add a proper quantity of water, and wafh
w the colour in the fame manner, as has been di-
t; reeled for lake, &c. and, when properly wafhed,
': proceed in the fame manner to dry it in lumps of
11 convenient fize."
The brightnefs, deepnefs, and coolnefs of Pruffian
blue, are proofs of its goodnels — for with thefe qua-
lities it may be depended upon in ftanding well.
Sophiftication, or any thing amifs in the procefs,
may be feen by its being more foul and purple.
V E R D I T E R,
Is formed by adding a due proportion of chalk to
a folution of copper, made by refiners in precipi-
tating the filver from the aquafortis, in the opera-
ration