COL 
name: it is a cold, but permanent colour: 
it is not miscible with water, but gives way 
to the sulphuric acid. 
Prussian blue is made with two parts of 
purified potash well mixed with one of 
dried bullock’s blood levigated : these are 
calcined in a covered crucible, with a mo- 
derate fire, until they cease to emit fumes. 
Blue verditer is made by absorbing the 
copper dissolved in aqua fortis, by aid of 
whitening. 
Smalt is pounded zaffre, made from the 
ore of zinc. 
Brice is levigated smalt, and rather 
lighter. 
All the above colours are very durable. 
PURPLE. 
The Croms-martis gives a simple purple, 
which colour may also be obtained from 
logwood, with a solution of tin. 
GREENS. 
Verdigris is an incrustation of copper by 
the corrosion of acids: it is highly poison- 
ous; but gives a beautiful green colour, 
with a very slight bluish tinge ; when boiled 
with vinegar, in an earthen vessel, it gives 
a highly transparent colour, fit for wasliing 
brass, &c. ; but tliis is vei’y apt to fede. 
Sap-green is the concreted juice of the 
buckthorn berry : it is a dull green, and is 
much in use though apt to fade. 
WHITES. 
Flake-white is an oxide of lead, formed 
by corrosion of that metal witli vegetable 
acids. 
White lead is the same as the above, but 
coarser; it is not so good as flake white, 
often turning black. 
Pure carbonate of lime stands perfectly 
well, and is much used : it is by some call- 
ed Spanish white, and is nearly the same as 
the pigments produced from egg shells, 
or oyster shells, calcined. 
Calcined hartshorn is an excellent white. 
The above catalogue of colours is intend- 
ed for the service of those who apply them 
with the brush, as in oil-painting, and in 
limning. The colours used by dyers are 
very different, and are chiefly pastil, woad, 
find indigo, for blues ; cochineal, carthamns, 
gum-lac, archil, logwood, madder, &c. for 
red ; weld, savory, quercitron, fenu-greek, 
&c. for yellows ; walnut bark, or rind, al- 
der bark, sandal wood, sumach, and soot, 
are used for browns, or, as they are techni- 
COL 
cally called, fawn-colours; for black, galls, 
copperas, &c. ; greens are generally com- 
pounds made from blue and yellow ; pur- 
ples from blue and red ; orange colour from 
red and yellow ; and many shades are made 
by the mixture of red and black, black and 
blue, &c. ; yellow and red also give an 
olive colour. See Dyeing. 
Colours diatonic, or musical scale of. In 
the course of Sir Isaac Newton’s experi- 
ments on the properties of light, he disco- 
vered the remarkable fact, that the spec- 
trum of the sun’s image, formed by refract- 
ed light, let into a darkened room, is longi- 
tudinally divided by the points separating 
the different colours; viz. violet, indigo, 
blue, green, yellow, orange, and red, into 
spaces which are respectively equal to r, 
-w ii> Ti, aiid i'^ parts of the double 
length of the spectrum; as, suppose the spec- 
trum to be 360 parts in length, then 
ffoi 720 ) #0) rfo) fim and 7557 will represent 
the length of each colour respectively, and 
adding these successively in the reverse or- 
der, to -^(70 iiave ^so 540 60s ois 
and ||g, which, in tiieir lowest terms, are 
2) tI) I) §) I) I) I) and 1, and appear to be 
the diatonic ratios answering to the octave, 
minor seventh, major sixth, fifth, minor 
fourth, minor third, major second, and key 
note. 
From the experiments of Henry Brough- 
ton, jun.. Esq., “ Philosophical Transac- 
tions, 1 ? 96 ,” it appears, that not only by 
refraction, but by inflection, deflection, 
and reflection, the rays of light may be se- 
parated on a chart or screen : and he men- 
tions numerous experiments, wherein the 
limits of the several colours on the spec- 
trum were carefully marked with the point 
of a needle, after which the papers thus 
marked were put away, and a fresh paper 
substituted for other experiments : the mea,- 
surement or comparison of the lengths of 
the intervals occupied by each colour on 
the different papers, being purposely de- 
ferred, until the whole course of experi- 
ments was completed, in order to prevent 
any preconceived opinions from operating, 
in making the experiments : the results are 
represented as agreeing, in the spaces, i, 
T 2 ) 12) IT) 85) and J-s, occupied by the violet, 
indigo, blue, green, yellow, orange, and 
red colours, being the very same, as to 
arrangement, as those by refraction above- 
mentioned. 
Colour of office, signifies some unjust 
action done under countenance of an oflipe, 
and is opposed ta virtute officii, which im- 
