cor. 
COLOPHONY. See Pharmacy. 
COLOSSUS, a statue of a gigantic or 
liormous size. The most famous of this 
ind was the colossus of Rhodes, made in 
onour of Apollo, by Chares the disciple of 
.ysippus. Ji was 8(3 feet high, and its thumb 
) large that few people could embrace it. 
I'his statue was placed across the mouth of 
! ie harbour at Rhodes, and the ships in 
ill sail passed betwixt its legs. 
COLOUR. See Optics. 
[ Colour, in painting, is applied both to 
the drugs, and to the tints produced by those 
drugs variously mixed and applied. 
I We shall, in this article give a brief account 
of the different pigments or colours which are 
used either in water or oil for the purposes 
of drawing or painting, 
f Red. Lakes. This term is used to denote 
a species of colours formed by the combina- 
tion of alumina, or the oxyd of tin, with the 
colouring matters of vegetables. The lakes 
fchiefiy used are red co lours ; and these are of 
different qualities, according to the basis and 
colouring matter employed; such as carmine, 
Florence-lake, and madder-lake. 
Carmine is a very rich bright crimson co- 
lour, and stands well in -water. For the pre- 
paration of carmine, four ounces of finely 
{pulverized cochineal are to be poured into 
four or six quarts of rain or distilled water, 
that has been previously boiled in a pewter 
kettle, and boiled with it for the space of six 
minutes longer. Eight scruples of Roman 
Jalum, in powder, are to be then added, and 
the whole kept upon the lire one minute long- 
er. As soon as the gross powder has sub- 
sided, and the decoction has become clear, 
jit is to be carefully decanted into large cy- 
lindrical glasses covered over, and kept un- 
j disturbed till a fine powder is observed to 
have settled at the bottom. The liquor is 
then to be poured off from this powder, which 
is to be gradually dried. From the liquor, 
! which is still much coloured, the rest of the 
{colouring matter maybe separated by means 
I of the solution of tin, when it yields a car- 
S mine little inferior to the former. 
Florentine lake is the kind in general use, 
j known by the name of lake. It is used in 
I water and also in oil, but does not stand ; 
which is much to be lamented, as it is a very 
beautiful colour, and there is no substitute 
that will completely answer all the purposes 
I of lake. The best sort may be prepared from 
] the sediment of cochineal that remains in the 
{ kettle after making carmine, adding to it a 
j small quantity of cochineal or Brazil-wood, 
jf and precipitating the colouring matter with a 
| solution of tin. 
Madder lake is very little known as a co- 
; lour. It is not so bright and rich a colour as 
i the last-mentioned lakes, but lias this valuable 
I advantage ; that it stands much better, and 
it may answer many of the purposes of Flo- 
rence lake. It is prepared nearly in the same 
manner as the foregoing. 
Rose-lake. This is generally called rose- 
j pink. It is a lake made by a basis of chalk, 
1 1 coloured by Brazil or Campeachy wood. It 
does not stand, and is only used for house- 
painting and paper-hanging. 
Vermilion, a bright scarlet pigment, form- 
ed from sulphur and quicksilver; when of a 
coarse kind, it is called cinnabar. Its good- 
jness is known by its brightness, and inclining 
! to & crimson hue. It is a very useful colour 
COL 
in oil, where it stands very well ; but in wa- 
ter it is apt to turn black. * 
Red-lead, or minium, is lead calcined till 
it acquires a red colour, by exposing it with 
a large surface to the lire. It is also made 
from litharge, which is a calx or oxyd of lead ; 
but is not so good as when made directly 
from metallic lead. This colour is very apt 
to turn black, both in water and oil, and is 
therefore seldom used but for very coarse 
purposes. 
Indian-red is a very useful colour, answer- 
ing some of the purposes of lake it stands 
weil botli in water and oil. It is difficult to 
procure the genuine kind, which comes from 
the East Indies. What is sold for Indian- 
red is said to be chiefly made in this coun- 
try. 
Venetian-red, is a native red-ochre, rather 
inclining to the scarlet than the crimson hue: 
it is not far different from the common In- 
dian red, but fouler, and is chiefly used by 
house-painters. 
Spanish -brown is also an earthy substance, 
found in the same state in which it is used ; 
it is nearly of the same colour as Venetian- 
red, but coarser. It is used only for the 
commonest purposes. It does not change. 
Light-red, or burnt ochre. This is com- 
mon yellow-ochre, heated red-hot in the fire, 
till the colour changes from yellow to a red. 
It is a very excellent colour, both in water 
and oil ; having the quality in common with 
all the ochres, of standing perfectly well. 
Red-chalk. This is the same substance as 
is used for drawing on paper, in the manner 
of a crayon. It is very much like light-red, 
and is used instead of it for some purposes. 
It stands perfectly well, and may be used 
both in water and oil. 
Burnt terra di Sienna. This colour is made 
by calcining raw terra di Sienna till it ac- 
quires a red colour. It is of a very rich tint, 
and is much used both in water and oil. It 
stands well in both. 
Blue. Ultramarine is prepared from la- 
pis lazuli, by calcining and washing it very 
clean. When genuine, it is an extremely 
bright blue colour, somewhat transparent both 
in oil and water, and stands perfectly well. 
On these accounts it is of the utmost value, 
being excellent in every kind of painting, 
even in enamel ; but its great price prevents 
the general use of it. 
Ultramarine ashes. This is the residuum, 
after washing the lapis lazuli, in which a por- 
tion of the ultramarine still remains. It is 
very subject to be adulterated. It is not so 
bright as ultramarine ; being like that colour, 
with a tint of red and white in it. When 
genuine it stands well. 
Prussian-blue. This colour is iron com- 
bined with a peculiar acid, called the prussic 
acid. It is made in the following manner : 
Two parts of purified potass are most in- 
timately blended with three parts of dried 
and finely pulverized bullock’s blood. The 
mass is first calcined in a covered crucible, 
and on a moderate fire, until no more smoke 
or flame appears ; and it is after this brought 
to a complete yet moderate ignition : or equal 
parts of potass and finely-powdered coals, 
prepared from bones, horns, claws, &c. are 
mingled, and heated in a covered crucible to 
a moderate redness. This done, either of 
these two calcined masses is, after cooling, 
lixiviated with boiling water, and the lixivium 
COL 391 
fibred. Nothing remains now but to make 
a solution of one part of green vitriol and 
two parts of alum ; and to add to it while yet 
hot the above lixivium, little by little how- 
ever; and to separate the greenish-blue pre- 
cipitate which then forms, by means ot a 
tiltre. If afterwards a si ght quantity ol di- 
luted muriatic acid is afiused upon this pre- 
cipitate, it assumes a beautiiul darl: -blue co- 
lour. The operation is terminated by edul- 
corating and drying the pigment thus pre- 
pared. Prussian-blue is an extremely beau- 
tiful colour when properly prepared, and 
stands well. Common Prussian-blue is apt 
to contain some iron, which causes it to turn 
greenish or olive. 
Verditer is a blue pigment, obtained by 
adding chalk or whitening to the solution of 
copper in aqua-fortis. 1 he best sort is pry- 
pared by the refiners ; who employ for this 
purpose the solution of copper which they 
obtain in the process of parting, by precipi- 
tating, silver from aqua fortis by plates of 
copper. Common verditer is made from the 
' sulphate of copper or blue, by the manufac- 
turers in Sheffield and Birmingham. Verdi- 
ter is only used for very coarse purposes, 
chiefly by the paper-stainers. It has been 
sometimes called sanders-blue, from igno- 
rance of the meaning of the term cenares 
blues, or blue ashes, which the French call it. 
Indigo. This colour is extracted from a 
plant that grows in the East and West Indies. 
It is not so bright as Prussian-blue, but it is 
cooler, and has the advantage of being very 
durable. It cannot be dissolved by water, 
but may by the sulphuric acid ; and it then 
forms bcott’s liquid blue, so much used lor 
colouring silk stockings, 8cc. 
Smalt. This is glass coloured with cobalt, 
and ground to a fine powder. Its coarseness 
prevents its being used much for painting in 
oil or water. It is employed sometimes by 
strewing it upon a ground of oil-paint. It is 
also used in enamel-painting. It stands 
well. 
Bice is only smalt more finely levigated. 
Yellozv. Indian-yellow. This is the bright- 
est of all yellows for water-colours, and is 
perfectly durable. It is said to be procured 
from the urine of the buffalo. In the East 
Indies it *is a very common and cheap co-> 
lour ; the natives there use it commonly for 
colouring their calicoes, which they do with- 
out any mordant ; so that the colour is wash- 
ed out again when the cloth is dirty. 
King’s-yellow. This colour is orpiment 
refined; which is a substance dug out of the 
earth, and consists of sulphur joined to arse- 
nic; or it may be prepared by subliming 
sulphur with arsenic. It is of a very bright- 
yellow, but does not stand well; and great 
caution should be used in employing it, as it 
is a strong poison. 
Naples-yellow. This is a very durable and 
bright yellow ; it comes from Naples, and is 
supposed to be prepared from lead and anti- 
mony. 
Yellow-ochre. This is an earth coloured 
by oxyd of iron. It is a cheap colour, and 
not very bright, but is valuable on account 
of its standing well. Roman-ochre is a supe- 
rior kind of yellow-ochre. 
Dutch-pink. I'his pigment is formed of 
chalk, coloured with the juice of French 
berries, or other vegetables affording a vei- 
