COL 
plies a man’s doing a right and just thing in 
the execution of his office. 
Colours, in the military art, include the 
banners, flags, ensigns, &c. of all kinds, 
borne in the array or fleet. See Ensign, 
Flag, Pendent, and Standard. 
COLOURING, in painting, one of the 
great component and essential parts of 
painting is the art of giving to every object 
in a picture its true and proper hue, as it 
appears under all tlie various circumstances 
or combinations of light, middle-tint, and 
shadow; and of so blending and contrast- 
ing the colours, as to make each appear 
w'ith the greatest advantage and beauty, at 
the same time that it contributes to the 
richness, the brilliancy, and the harmony of 
the whole. It likewise possesses powers 
which, when judiciously applied, render it 
highly conducive to the character and ex- 
jiression of the subject represented. See 
Painting. 
Colouring matter. It has been sup- 
posed, that a peculiar proximate principle 
exists in vegetables, in which their colour 
frequently resides, and which has hence re- 
ceived the name of colouring matter. 
The colouring matter of vegetables is 
scarcely ever found insulated, but is mixed 
or combined with other principles. In this 
state it exists in tlie leaves and flowers, in 
the bark and in the wood of the stem and 
roots. It is extracted, and obtained more 
pure, by the action of those agents which 
are capable of dissolving it. In many cases, 
water, cold or warm, is sufficient for tliis 
purpose. If logwood, brazil wood, mad- 
der, weld, or quercitron bark, for example, 
be macerated in water, the matter on which 
the colour depends is dissolved ; a transpa- 
rent solution, more or less deeply coloured, 
is obtained ; and, by repeating the macera- 
tion with water sufficiently, nothing at 
length remains but the mere ligneous fibre. 
Sometimes, however, the colouring matter 
is not soluble in water : it is then frequently 
soluble in alcohol ; and in a few substances, 
is even best dissolved by oils essential or 
expressed. 
tVIien the colouring matter is in solution, 
it may be attracted from the solvent by 
other substances with which it enters into 
combination ; and this, in some measure, 
gives it a more appropriate character. 
There are some substances even which ap- 
pear in general to exert strong affinities to 
colouring matter, particularly alumina and 
some of the metallic oxides. If alumina be 
diffused or boiled in a coloured vegetable 
COL 
infusion, it often happens, that the colour- 
ing matter combines with it, and leaves the. 
water of the infusion perfectly colourless. 
Or if alum be dissolved in a coloured infu- 
sion, and it be decomposed by the addition 
of an alkali, the alumina in the moment of 
its precipitation attracts the colouring mat- 
ter, forms a coloured precipitate, and, if the 
due proportions have been observed, the 
liquid will remain colourless. In like man- 
ner if a coloured infusion be boiled with a 
metallic oxide, it often happens that the 
colouring matter is attracted by the oxide. 
Thus Berthollet obtained combinations by 
this process of the colouring matter of log- 
wood, and other dye-stuffs, with oxide of 
copper and oxide of tin. Or if certain metal- 
lic salts be dissolved in the infusion, and be 
then decomposed by an alkali, the oxide in 
precipitating equally atttracts the colouring 
matter. It is from similar affinities to the co- 
louring matter that it is often attracted by 
linen, cotton, silk, or wool, from its solu- 
tions ; and even where the affinities of 
these are not sufficiently powerful, they 
may be rendered capable of attracting it, 
or the combination may be rendered more 
permanent by their being impregnated 
with another substance, which has towards 
it a still stronger attraction. See Dyeing. 
COLPODA, in natural histoiy, a genus 
of the Vermes Infusoria : worm, invisible to 
the naked eye, vei-y simple, pellucid, flat- 
sinuate. There are seven species, of which C. 
lamella, in water, resembles a long narrow 
pellucid membrane, narrower and obtuse 
behind, curved towards the top, with a 
ridge or fold gohig through the middle : it 
moves to and fro on its edge, and not on the 
flat side. 
COLUBER, in natural history, a genus 
of serpents distinguished by having plate* 
on the belly, and scales on the under parts 
of the tail. The species of this genus arc 
numerous. Linnaeus describes, upon the 
testimony of various w'riters, above ninety ; 
and that number even has been considera- 
bly augmented by naturalists since his time. 
The species differ greatly in size and habit ; 
some, as the vipers having tlie head large, 
flattish, and semi-cordated, with the body 
and tail of a moderate length, or rather 
short ; while others, as the greater part of 
the harmless serpents, have small heads, 
with the body and tail much longer in pro- 
portion. In some, exclusive of the usual 
scales under the tail, are a few scuta or 
undivided lamellae, either at the beginning 
or towards the tip of the tail. 
