3. (ttinger.) Ether of cantharides and collodion, equal parts.
_Use._ Vesicating collodion is used as an irritant. No. 1 was introduced in 1862, and has many advantages over the other two. Mr Tichborne thus described the most effectual method of using it in the 'Pharm.
Journ,':--"The part upon which the blister is to be raised should be painted with the vesicant to the desired extent, bearing in mind that the blister produced always extends to about one tenth of an inch beyond the margin of the space covered. Care should be taken to give a coating of considerable thickness, and to ensure this result the brush should be passed over and over again, until about 1/2 dr. has been used to the square inch, or less when operating upon a tender epidermis. It is desirable to place over the intended blister a piece of oil silk, or, what is still better, a piece of sheet gutta percha, somewhat larger than the surface painted, as this will stop the exhalations of the skin, and so render it moist and permeable. In ten minutes, or a quarter of an hour if the cuticle is hard, the collodion should be wiped off with a little cotton-wool moistened with ether, when the blister will almost instantly rise."
=COL'LOID.= See DIALYSIS.
=COLLYR'IUM.= [L.] In _medicine_ and _pharmacy_, a topical remedy for diseases of the eye. Formerly the term collyrium was applied to any medicament employed to restrain defluxions.
=Collyr'ium, Dry.= _Syn._ EYE POWDER; COLLYR'IUM SIC'CUM, L. _Prep._ 1.
(Dupuytren.) White sugar, 1 dr.; red oxide of mercury, 10 gr.; oxide of zinc, 20 gr.; mix.
2. (Lagneau.) Sugar candy, 2 parts; nitrate of potassa, 1 part.
3. (Falconer.) Chloride of barium, 1 gr.; sugar candy, 1 dr.
4. (Radius.) Calomel and white sugar, of each 1/2 dr.; opium, 10 gr.
5. (Recamier.) Oxide of zinc and sugar candy, equal parts.
6. (Velpeau.) Trisnitrate of bismuth and sugar candy, equal parts.
7. (Wiseman.) Acetate of soda, 10 gr.; powdered opium, 1 gr.; sugar candy, 1/2 dr.
_Obs._ It is absolutely necessary that the ingredients in the above preparations should be reduced to an impalpable powder by careful trituration in a wedgwood mortar. For use, a small pinch is placed in a quill or straw, and blown into the eye previously opened with the fingers.
On the whole, they may be regarded as unnecessary preparations, and are unsafe, except in skilful hands.
=Collyrium, Liq'uid.= See WATERS (Eye).
=Collyrium, Unct'uous.= See OINTMENTS (Eye).
=COL'OCYNTH= (sinth). _Syn._ COLOCYNTH PULP., COLOCYNTHIDIS PULPA, B. P.
BIT'TER AP'PLE, BITTER GOURD, BITTER CU'CUMBER, PEELED COLOCYNTH; COLOQUINT'IDA, COLOCYNTH'IS (B. P.), L. The decorticated fruit or pulp of the _Citrellus Colocynthis_ (Schrad.--Ph. L.), or _Cucumis Colocynthis_ (Linn.--Ph. E. & D.). It is an acrid, drastic purge and hydragogue, and cannot be given alone with safety; but, in combination with other substances, it forms some of our most useful cathartic medicines.
=COLOCYNTH'IN.= _Syn._ COLOCYNTH'IUM, L. The bitter, purgative principle of colocynth.
=COL'OPHENE.= Formed by distilling oil of turpentine with concentrated sulphuric acid. A colourless, viscid, oily liquid; with a high boiling-point; and exhibiting a bluish tint by reflected light.
=COL'OPHONY.= See RESIN.
=COLORADO BEETLE.= _Syn._ _Doryphera decemlineata._ The Colorado potato beetle belongs to the family _Chrysomelidae_, and is a native of the eastern slopes of the Rocky Mountains. It measures nearly half an inch in length, and has a tawny or yellowish cream-coloured body, darkly spotted; with wing cases which are marked with ten black longitudinal stripes. It has been gradually migrating eastward toward the more cultivated lands of the Northern states, until it has reached the Atlantic coast. It is now found over all the central and northern parts of the United States east of the Rocky Mountains, as well as throughout Canada, on the potato crops of all of which regions it has committed incalculable ravages. The leaves and stalks are the parts of the potato plant principally attacked; the depredators being, for the most part, the larvae, of which three broods are said to be produced annually.
In America, we believe, the only means of destroying these insects as well as their eggs and larvae consists in the application to the plant of the highly poisonous and dangerous pigment, Scheele's green, a hydrated arsenite of copper. M. Girard recommends in preference to the arsenical salt a liberal use of sulpho-carbonate of potash.
=COLOUR BLINDNESS.= _Syn._ DAL'TONISM. A curious defect of vision, from which the eye is incapable of distinguishing colours. It is of three kinds:--1. An inability to distinguish any colour properly so called, the person being only able to distinguish white and black, light and shade. 2.
An inability to distinguish between the primary colours, red, blue, and yellow, or between these and the secondary or tertiary hues, such as green, purple, orange, and brown. 3. An inability to distinguish nicer shades and hues, as greys and neutral tints. The first form is rare; the second and third are common. Dr George Wilson found that of 1154 persons examined by him in Edinburgh, 65, or 1 in 177, were colour blind; of these, 21 confounded red with green, 19 brown with green, and 25 blue with green.
=COL'OURING.= _Syn._ BRANDY COLOURING, BREWER'S C., SPIRIT C. CAR'AMEL; ESSEN'TIA BI'NA, L. _Prep._ Brown sugar is melted in an iron vessel over the fire until it grows black and bitter, stirring it well all the time, after which water is added, and it is boiled to a syrup. In the making of brandy colouring white sugar is more frequently used.
_Obs._ Some persons use lime-water to dissolve the burnt sugar. Care must be taken not to overburn it, as a greater quantity is thereby rendered insoluble. The heat should not exceed 430, nor be less than about 400 Fahr. The process, for nice experiments, is best conducted in a bath of melted tin, to which a little bismuth has been added to reduce its melting-point to about 435; a little powdered resin or charcoal or a little oil being put upon the surface of the metal, to prevent the oxidisement of the alloy. See CARAMEL.
=COL'OURS.= White light from the sun is of a compound nature, and may be decomposed into rays of different colours. Newton distinguished seven PRIMITIVE COLOURS, namely, violet, indigo, blue, green, yellow, orange, and red. Sir D. Brewster is disposed to think that four of these colours are really compound, and that three, namely, blue, yellow, and red, alone deserve the name of primitive. The colours of natural objects are supposed to result from the power possessed by their surfaces of absorbing some of the coloured rays of light, while they reflect or transmit, as the case may be, the remainder of the rays. Thus, an object appears red because it absorbs or causes to disappear the yellow and blue rays composing the white light by which it is illuminated. Black and white are not colours, strictly speaking.
A body is said to be black when it absorbs or quenches a large proportion of all the rays of white light falling upon it. A body is said to be white when it receives the white light, and reflects all the rays with moderate strength. Grey may be regarded as a luminous black or dark white. The names given to colours are far from being satisfactory, for although many thousand shades may be distinguished by a practised eye, it is a question whether there are fifty names which would convey the same idea of shade to any ten colourists in the world. The names taken from natural coloured objects, as indigo, violet, orange, lilac, amber, emerald, &c., are the least objectionable. M. Chevreul has devised an ingenious system of naming and classifying colours. He employs only 6 fundamental names, which are those of the three elementary colours, red, yellow, and blue; and of the three secondary colours, orange, green, and violet. By the direct union of the elementary and secondary colours, 6 tertiary colours are formed. He arranges the twelve colours in a circle, like the spokes of a wheel, commencing with the red, and going to the right, thus:--Red, red-orange, orange, yellow-orange, yellow, yellow-green, green, blue-green, blue, blue-violet, violet, red-violet. The chromatic circle is completed by placing 5 shades between the red and red-orange, 5 between the red-orange and orange; and so on between each of the other couples. This chromatic circle of 72 colours is not imaginary, but actually exists, composed of dyed wools. The shades are distinguished by numbers; thus there are red, 1 red, 2 red, 3 red, 4 red, and 5 red, &c. Each of the 72 shades has, moreover, 20 different degrees of depth, from the lightest that can be discerned from pure white to the most intense depth, approaching to brown and black. These degrees of depth are called tones or tints. The addition of these tones to the chromatic circle brings up the number of tints to 1440. To indicate any one of these tints we have merely to write the number of the shade, and after it the number of the tone, as, for example, 3 blue-violet, 13 tone. By mixing each of the 1440 tints with grey or black, so as to darken it in different degrees, a total of 14,440 colours may be defined. This part of the system is generally regarded as unnecessary. Mr O'Neill, in his valuable 'Dictionary of Calico Printing and Dyeing' (to which work we refer the reader for a full account of Chevreul's classification), gives a long list of colours and coloured bodies, which are pretty well defined in common language with the names of the colours, according to this ingenious system. We select from this list the following examples:--
Amber in mass = 2 orange, 12 tone.
Amethyst = 5 blue-violet, from 3 to 16 tone.
Blood, ox = 1 red, 13 and 14 tones.
Butter = yellow-orange, 2 to 3 tone.
Carrot = orange, 7 tone.
Chocolate in cake = 5 orange, 18 tone.
Emerald = 2 green, 11 tone.
Green, apple = 4 yellow-green, 8 tone.
Isabelle = 1 yellow-orange.
Mauve = 3 violet, 8 tone.
Red-lead = yellow-orange, 20 tone.
Ruby = red, 11 tone.
Yellow, canary = 1 yellow, 6 tone.
For notices of DYES, PIGMENTS, &c., refer to the principal colours.
=Colours, Cake.= _Syn._ ARTISTS' COLOURS. These are made by grinding by means of a glass muller and a slab, the respective pigments previously reduced to powder, into a smooth paste with equal parts of isinglass size, and thin gum water. The paste is then compressed into squares as tightly as possible, and dried with a very gentle heat. Old crumbling cake colours should be powdered very finely in a biscuit-ware mortar, sifted through fine muslin, and ground up as above, the gum water being omitted. The powders rubbed up with honey to the consistence of cream constitute moist colours.
=Colours, Complement'ary.= _Syn._ ACCIDENT'AL COLOURS. Colours are said to be complementary to each other which, by blending together, produce the perception of whiteness. According to Mayer, all colours are produced by the admixture of red, yellow, and blue light, in certain proportions; and by intercepting either one or more of these coloured rays in a beam of light, those which meet the eye will consist of the remaining coloured rays of the spectrum. Thus, by intercepting the red rays in a beam of white light, the remaining yellow and blue rays will produce a green colour; by intercepting the blue rays, the remaining yellow and red will give an orange; and so on of other cases; so that red and green, blue and orange, are COMPLEMENTARY COLOURS. If we look for some time, with one eye, on a bright-coloured object, as a wafer, placed on a piece of paper, and subsequently turn the same eye to another part of the paper, a similarly shaped spot or mark will be seen, but the colour will vary, though it will be always the same under like circumstances. Thus, if the original spot or wafer be of a red colour, the imaginary one will be green; if black, it will be white; the imaginary colour being always complementary of that first gazed upon. The colour so perceived is often called an ACCIDENTAL COLOUR, to distinguish it from the real colour. It is a general maxim in design that "colours look brightest when near their complementary colours."
=Colours, Drug'gists' Show.= See SHOW BOTTLES.
=Colours, Flame.= See FIRES (Coloured).
=COLTS'FOOT.= This popular herb is the _Tussilago farfara_ of Linnaeus. It is a demulcent bitter, and is slightly stomachic and tonic. It is much esteemed by the lower classes in coughs, shortness of breath, and other affections of the chest. The leaves form the basis of most of the British herb tobaccos, and have been recommended to be smoked in asthma and difficulty of breathing.--_Dose._ One or two wine-glassfuls of the tea or decoction (1 oz. to the pint) _ad libitum_.
=COLUM'BIC ACID.= See TANTALIC ACID.
=COLUM'BIUM.= See TANTALUM.
=COMA.= A deep, heavy sleep, from which the patient cannot be aroused. See APOPLEXY.
=COMACHROME FOR DYEING THE HAIR BLACK.= Nitrate of silver solution, with pyrogallic acid. (Reveil).
=COMBINA'TION.= In _chemistry_, the union of dissimilar substances. The great general laws which regulate all chemical combinations admit of being laid down in a manner at once simple and concise. The laws of COMBINATION BY WEIGHT are as follows:
"1. All chemical compounds are definite in their nature, the ratio of their elements being constant.
"2. When any body is capable of uniting with a second in several proportions, these proportions bear a simple relation to each other.
"3. If a body, A, unite with other bodies, B, C, D, the quantities of B, C, D, which unite with A, represent the relations in which they unite among themselves, in the event of union taking place.
"4. The combining quantity of a compound is the sum of the combining quantities of its components." (Fownes.)