DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.19571#0060
|6 Till-: ARTIST'S ASSISTANT.
'; any lighter iubftance that mav have formed in the
t( neck, and appears to be diiTimilar to the reft. Le-
" vigate the more perfect part ; and. when reduced
t; to fine powder, it will be vermillion proper for
" ufe : but on the perfeetnefs of the levigation, de-
<J pends, in a great degree, the brightness and good-
nefs of the vermillion. In order therefore to per-
" form this, it is neceffary that two or three mills
" of different clofenefs fhould be emploved, and
•: the laft Ihould be of fteel, and fet as finely as
'• poffible."
It is common, perhaps general, for dealers to fo-
phifticate vermillion with red lead. But to dete<£t
with certainty the fraud, both with refpect. to the ge-
neral fact, and the proportion, ufe the following
means :
Take a fma.il, but known quantity of vermil-
" lion lufpectcd to be adulterated, and put it into a
crucible having firfl. mixed with it about the fame
i: quantity, in bulk, of charcoal dull : put the cruci-
" ble into a common fire, having firfl covered it with
" a leffer crucible inverted into it ; and give a heat
11 iufficient to fufe lead ; when the crucible being
*• taken out of the fire, Ihould be well fhaken, by
linking it againft the ground. If the fufpected
•■ adulteration has been pracfifed, the lead will be
" found reduced to its metalline ftate, in the bottom
M ol the crucible ; and, being weighed, and com-
" pai-ed with the quantity of cinnabar that was put
*: into the crucible, the proportion of the adultera-
" tion may be thence certainly known. But. if no
" lead be found in the crucible, it mav be fafely in-
" fcrrcd, that no red lead had been commixt with
the vermillion.''
NATIVE
'; any lighter iubftance that mav have formed in the
t( neck, and appears to be diiTimilar to the reft. Le-
" vigate the more perfect part ; and. when reduced
t; to fine powder, it will be vermillion proper for
" ufe : but on the perfeetnefs of the levigation, de-
<J pends, in a great degree, the brightness and good-
nefs of the vermillion. In order therefore to per-
" form this, it is neceffary that two or three mills
" of different clofenefs fhould be emploved, and
•: the laft Ihould be of fteel, and fet as finely as
'• poffible."
It is common, perhaps general, for dealers to fo-
phifticate vermillion with red lead. But to dete<£t
with certainty the fraud, both with refpect. to the ge-
neral fact, and the proportion, ufe the following
means :
Take a fma.il, but known quantity of vermil-
" lion lufpectcd to be adulterated, and put it into a
crucible having firfl. mixed with it about the fame
i: quantity, in bulk, of charcoal dull : put the cruci-
" ble into a common fire, having firfl covered it with
" a leffer crucible inverted into it ; and give a heat
11 iufficient to fufe lead ; when the crucible being
*• taken out of the fire, Ihould be well fhaken, by
linking it againft the ground. If the fufpected
•■ adulteration has been pracfifed, the lead will be
" found reduced to its metalline ftate, in the bottom
M ol the crucible ; and, being weighed, and com-
" pai-ed with the quantity of cinnabar that was put
*: into the crucible, the proportion of the adultera-
" tion may be thence certainly known. But. if no
" lead be found in the crucible, it mav be fafely in-
" fcrrcd, that no red lead had been commixt with
the vermillion.''
NATIVE