DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.19571#0077
THE ARTIST'S ASSISTANT. 63
*< Take of the refiners folution of copper made in
*: the precipitation of filver from the fpirit.of nitre ;
<; or diffolve copper in fpirit of nitre or aquafortis,
" by throwing in filings or putting in flips of copper
" gradually, till all effervefcence ceafe. Add to it of
t; ftarch finely powdered, the proportion of one
" fifth or fixth of the Weight of the copper diffolved.
<; Make then a folution of pearl afhes, and filter it;
<: and put gradually, to the folution of copper, as
" much as will precipitate the whole of the copper ;
" which may be known by the fluid's becoming
" clear and colourlefs, though before highly tinged
'; with green. Wafh the powder, which will be
£: precipitated, in the manner direfted for lake, &c.
'; and, when it is fo well drained of water by means
" of a filter, as to be of a proper confidence, grind
6i the whole -well together, and lay it out to dry."
INDIGO.
This was formerly almoft the only blue colour ufed
in painting. It is made in the Spanifh Weft-Indies,
by means of putrefa&ion from certain plants, and a
coagulation by the air. It cannot (as far as is hither-
to known) be prepared in thefe colder climates, on
account of the tender nature of the plants which pro-
duce it. The indigo brought from the French, of
our own plantations, is foul, and greatly inferior in
brightnefs to that formerly imported hither from
the Spaniards, it being equal to the pruffian blue
for fome purpofes ; and there is no other prepar-
ation neceffary to ufing it in painting, except a per-
feft levigation.
SMALT,
*< Take of the refiners folution of copper made in
*: the precipitation of filver from the fpirit.of nitre ;
<; or diffolve copper in fpirit of nitre or aquafortis,
" by throwing in filings or putting in flips of copper
" gradually, till all effervefcence ceafe. Add to it of
t; ftarch finely powdered, the proportion of one
" fifth or fixth of the Weight of the copper diffolved.
<; Make then a folution of pearl afhes, and filter it;
<: and put gradually, to the folution of copper, as
" much as will precipitate the whole of the copper ;
" which may be known by the fluid's becoming
" clear and colourlefs, though before highly tinged
'; with green. Wafh the powder, which will be
£: precipitated, in the manner direfted for lake, &c.
'; and, when it is fo well drained of water by means
" of a filter, as to be of a proper confidence, grind
6i the whole -well together, and lay it out to dry."
INDIGO.
This was formerly almoft the only blue colour ufed
in painting. It is made in the Spanifh Weft-Indies,
by means of putrefa&ion from certain plants, and a
coagulation by the air. It cannot (as far as is hither-
to known) be prepared in thefe colder climates, on
account of the tender nature of the plants which pro-
duce it. The indigo brought from the French, of
our own plantations, is foul, and greatly inferior in
brightnefs to that formerly imported hither from
the Spaniards, it being equal to the pruffian blue
for fome purpofes ; and there is no other prepar-
ation neceffary to ufing it in painting, except a per-
feft levigation.
SMALT,