426 
PIGM 
phlogifton, and fubje&ed to an intenfe fire, it always 
turns out red; but the mixture of a Email quantity of 
inflammable matter gives it a purplifh caft. Hence va¬ 
rious paints are kept in the (hops under different names ; 
which yet differ from each other only in the flight circum- 
ftances above-mentioned; and fuch are the fcarlet-ochre, 
Spanifli brown, and terra di Sienna burnt. It is remark¬ 
able, that the oxydes of iron never fhow their colour till 
they become cold. 
Mr, Atkinfon’s patent, for making Venetian red and 
fome other colours of a fuperior quality, is dated as far 
back as the year 1794.; any one may therefore now purfue 
liis method, which is as follows: “With regard to the 
making or manufacturing of the faid paint or colour 
called Venetian red, I do declare, that the material of 
which the faid Venetian red paint or colour is made, is 
precipitated ochre, or earth of iron, otherwife called cro¬ 
cus martis, or faffron of Mars, (oxyde of iron ;) and that 
the fame mult be diluted with water in an iroai or other 
boiler or furnace, the fire or heat applied till the water 
and ochre boil, or attain a boiling heat; in which ftate it 
parts with mod of its ferruginous mixtures; and, after 
handing about five minutes, the heterogeneous particles 
will fall to the bottom of the boiler, and the finer parts 
muft be taken therefrom, and conveyed into a pan or 
receiver, or other veflel capable of bearing heat; and fire 
or heat mull be urged or applied till the whole is fuffi- 
ciently dry; or the fame maybe dried by the fun or 
wind. In that ftate it muft be removed to a calcining- 
furnaceor oven, commonly called a reverberatory-furnace, 
where, by the aftiftance of a bright flame conveyed over 
the top of it for about eight hours, the colour is changed 
from a yellow to a bright-red colour; in which ftate it 
muft be drawn from the furnace or oven, and, when cold, 
muft be ground by a mill or machine; regai’d being had 
to the colour being duly mixed with water. After which 
it muft be conveyed from the mill or machine, by a plug 
about twelve inches from the bottom of the tub, into 
i'pouts which carry it into fine fieves; whence it muft be 
received into cifterns or veffels which communicate one 
with another by fpouts, or otherwife, by which means the 
finer particles float into the farther part of the cifterns. 
I make ufe of fix cifterns in number, but a greater or lefs 
number may be ufed; and in this ftate, after Handing 
about twenty-four hours, the water is to be drawn from 
the colour, and then mixed with alabafterand chalk, both 
finely ground ; after which it muft be dried. 1 ufe for 
that purpofe a drying-loft made with Venetian blinds, 
which admit of a current of air, and put the colour in 
earthen diflies, about ten inches wide and four inches 
deep. The colour is then in the form of a cake, in which 
ftate it is faleable; but, when it is ordered in powder, 
it muft be finely ground.” 
Vermilion and red-lead are very durable colours : the 
firft is the belt red ufed in oil-painting, but does not 
anfwer well in water; the other is rather an orange; and, 
like other preparations of lead, is in fome cafes apt to 
turn black. 
4. Orange.— The only true orange-coloured paints 
are red orpiment and orange lake. The firft is a fublimate 
formed of arfenic and fulphur; the other may be pre¬ 
pared from turmeric infufed in alcohol having its colour 
itruck upon oxyde of tin, and brightened by a folution 
of that metal. All the fit ad es of orange, however, may be 
extemporaneoufly prepared by mixing red and yellow 
colours together, in due proportions. 
5. Yellow. —The yellow paints moft commonly in 
ufe are, king's yellow, Naples yellow, Dutch pink, En- 
glifli pink, mafticot, common orpiment, yellow-cchre, 
terra di Sienna unburnt, and turbith mineral. 
King’s yellow is evidently an arfenical preparation. 
Its colour is exceedingly beautiful, but apt to fade; on 
which account, and its great price, it is feldom ufed. 
Naples-yellow, orgiallolino, is a porous heavy granular 
fubjlar.ee, of an earthy nature; it is friable, adheres a 
ENT. 
little to thetongue, and, when expofec! to the air, neither 
undergoes decompofition nor changes its colour, which 
is a pale orange yellow. Reduced to an impalpable 
powder, it remains fufpended in the water for a confide- 
rable time, and at laft falls down as a pally mafs. Boiled 
in water, the fluid acquires a fait tafte. It does not effer- 
vefee with acids, but is partly diflolved by nitro-muriatic 
acid ; it is fufed with difficulty, and in this ftate under¬ 
goes no change, except that its colour becomes rather 
more red. When filled with colourlefs glafs, the produdl 
is a milk-white enamel, which proves the abfence of iron. 
When mixed with inflammable fubftances a regulus is 
obtained, which appears to be a compound of lead and 
antimony. 
This article is principally brought to us from Naples; 
generally in the fliape of an earthy cruft, from three to 
four lines thick, and fometimes exhibiting the fliape of 
the veflel in which it has been fuft’ered to harden. It is 
alfo often feen as powder. It is not known with certain¬ 
ty at what period this fubftance became an objeft of 
commerce. Pomet is the firft writer on drugs who makes 
mention of Naples yellow, and he obferves that it is ex¬ 
tremely fcarce. Kunkel, who gives a pretty complete 
lift of the fubftances ufed for colouring glafs and enamel, 
is filent refpedfing Naples yellow, or giallolino : but, if 
the name of this production can be confldered as a proof 
of its antiquity, it may be faid to have been known in 
Italy as early as the end of the 16th century. Ferrante 
Imperato (peaks of two forts of giallolino, one of which 
appears to be the oxyd of lead, called mafficot, while the 
other is unquestionably the fubftance under confideration. 
But no writers on colours appear to have been acquainted 
with the nature of the true Naples yellow; fome have 
confldered it as a volcanic production of mounts Vefuvius 
and Etna ; others as a variety of native ochre; Guettard 
(Mem de l’Acad. des Sciences, 1762) miflook it fora 
bolar earth ; but Pott (Lithogeognolle, p. 2.) is neareft 
the truth, for he fufpeCts it to be the refult of artificial 
preparation. Fougeroux (Mem de l’Acad. des Sciences, 
1766) fubferibed to Pott’s opinion, and pointed out a 
method of preparing this colour by boiling a mixture of 
twelve parts of white lead, one of alum, one of fal ammo¬ 
niac, and three parts of oxyd of antimony, (Ant. diapho- 
reticum.) But, before Fougeroux, (who had probably 
acquired fome knowledge of this procefs on his travels 
in Italy,) a more exaCt account of the manner of prepa¬ 
ring this colour had been given by Giambattifta Pafleri 
in his interefling work on porcelain painting. The in¬ 
gredients, according to this author, are, one pound of 
antimony, one pound and a half of lead, one ounce of a 
fait which he calls alhnne clifeccia, and the fame quantity 
of common fait. It is probable that this receipt was not 
unknown to Fougeroux, who miftook the allumc di feccia 
for common alum. But profefl'or Beckmann (from feve- 
ral circumftances relative to the various methods of pre¬ 
paring this colour deferibed by Pafleri) is of opinion, 
that allume di feccia is meant for tartrate of potafli (fait 
of tartar); and indeed Pafleri often makes ufe of the word 
feccia alone, which certainly implies tartar. See Pafleri 
in Nuova Raccolta d’Opufcoli fcientifichi, vol. iv. 
After the publication of Fougeroux’s Memoir, De 
Laiande deferibed another method of preparing the Naples 
yellow, which he had obtained from prince San Severo. 
According to him, only lead and antimony are employed. 
Take lead perfedlly oxydated, pafs it through a fieve, and 
mix it with a third of its weight of antimony prepared in 
the fame manner. After this, take a large dilh of unglazed 
earthenware, cover it with a fheetof white paper, and lay 
on the powder fo as to be two inches in thicknefs. Thele 
dilhes are to be placed at the upper part of a potter's 
furnace, where the reverberation of the flame is fufficient 
to produce the defired refult. After having been ex- 
pofed for fome time to this moderate degree of heat, a. 
hard yellow-coloured mafs will be found, which is to be 
triturated with water on a ftone, and afterwards ptit into 
veflels 
