Gesellschaft, vol. xviii., p. 1,969, the following analysis of a

More recently, in the Journal für praktische Chemie, 1890, No. 3, Lafar published the following analysis of carmine :

The two analyses agree with one another as well as analyses of a commercial and variable product like carmine can be. expected to agree. The lime and alumina in the ash are in the proportion of 2 Ca O: Al1⁄2 0; this circumstance would point to the fact that carmine is not purely an alumina lake, but a lime-alumina lake, with some proteid matter. The tin and copper in the ash have probably been derived from the vessels in which the cochineal has been boiled, as it is often recommended in recipes for carmine-making, to make the decoction

of cochineal in two vessels; the other constituents are of no importance.

The following methods have been published for preparing carmine:

1. 1 lb. of cochineal is extracted by boiling in water for from 15 to 20 minutes, the decoction is strained off, 1 oz. of alum is added, and the boiling continued for a few minutes longer; the clear liquor is decanted off and 1 oz. of cream of tartar added; the mass is then allowed to stand for the carmine to settle.

2. Boil up 2 lbs. of cochineal, strain off the decoction, add 2 ozs. of alum, 3 ozs. of muriate of tin (a solution of stannous chloride), 2 ozs. of carbonate of soda, and allow to stand for 2 days, when the carmine will have been thrown down.

3. 1 lb. of cochineal is boiled with water and oz. of carbonate of soda; to the decoction is added 1 oz. of alum and 3 drams of cream of tartar; the mixture is allowed to stand for the carmine to be deposited.

4. The following process was patented by Wood, in 1856:9 ozs. of sodium carbonate, 8 ozs. of citric acid, and 27 quarts of water, are boiled together; then 11⁄2 lbs. of cochineal are added and the mixture boiled for 1 hours, strained, and clarified; the liquor is heated to the boil and 9 ozs. of alum are added; the mass is then boiled for 5 minutes longer and allowed to stand for 3 days, when the carmine precipitated is collected, washed, and dried.

A recipe was published by Madame Cenette, of Amsterdam, a noted maker of carmine, but this is defective, and carmine cannot be made by following it.

In the preparation of carmine it is advisable to use tin or tinned-copper vessels for boiling the cochineal in, as a small quantity of the metal dissolves in the liquor and exerts a beneficial influence on the carmine which is produced. Earthenware vessels may be used, but iron must be avoided, as any trace of iron in solution affects the shade of the carmine rather injuriously. The use of too much alum should be avoided, as it tends to reduce the colouring power of the carmine and also to alter the tint, turning it more crimson, while the shade ought to be a scarlet.

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Carmine is a deep fiery-scarlet powder, slightly varying in tint; the best quality is known commercially as nacarat carmine." It is insoluble in water, alcohol, ether, turpentine, and all the vehicles used in mixing paints, but soluble in strong mineral acids. In caustic soda, caustic potash, and ammonia solutions, it dissolves with a deep crimson colour, from which

solutions the carmine can be precipitated by exposure to the air or by the addition of weak acids like acetic or tartaric acid; the carmine so obtained is very little changed from the original, so far as tint is concerned. Solutions of salts of iron, lead, &c., have an injurious effect on the tint of the carmine. Carmine, on being heated in a crucible, burns and leaves behind from 7 to 10 per cent. of a white ash, which consists principally of alumina and lime, as will be seen on examination of the analyses given above.

As a pigment carmine works well in either water or oil, and is used, to a small extent, by artists as a glazing or tinting colour. It is not permanent, as a few months' exposure to sun and air is sufficient to impair the brilliancy of its hue, and prolonged exposure causes it to fade.

Carmine is frequently adulterated with other lakes and red pigments. The fact of adulteration may be ascertained by treating the lake with ammonia, when, if pure, it will completely dissolve; if not pure, the adulterant is left as an insoluble residue.

CARMINE LAKE.—In preparing carmine the whole of the colouring matter of the cochineal is not precipitated, and therefore the liquors from the carmine are strongly coloured, and are utilized for the preparation of carmine lake. The usual method

of making is to add to the liquors a small quantity of alum (about one-fourth of the weight of the cochineal used in making the liquor originally), a little tin chloride, and then sufficient potash carbonate solution to precipitate the whole of the alum and tin; the precipitate is collected, washed, and dried.

Another method is to make a decoction of cochineal, and to add to this freshly-precipitated alumina (obtained by adding ammonia to a solution of alum, and collecting the precipitate of alumina); the colouring matter is absorbed by the alumina, and a lake is formed; only sufficient of the alumina is added as will produce a lake of the required depth of colour.

1 lb. of cochineal is boiled in water, and 1 lb. of cream of tartar or carbonate of potash is added; then 1 oz. of tin chloride is added, and sufficient alum to throw down all the potash salt and the colouring matter of the cochineal; the lake obtained is collected, washed, and dried.

FLORENTINE LAKE is carmine lake which is, after making, mixed with a small quantity of gum water and moulded into the form of tears or drops. Sometimes cheap qualities of Florentine lake are prepared by mixing the genuine article and a lake made from Brazil wood together.

Crimson-Lake and Scarlet-Lake are prepared from cochineal

in the same way as carmine-lake, but the proportions of alum and tin used differ, and the precipitated lake is moulded into the form of drops. *

BRAZIL-WOOD LAKES.-2 lbs. of Brazil wood are digested in 8 gallons of water for 24 hours; then the mass is boiled for half-an-hour or so, strained, and allowed to stand for a few days or a week; this is necessary if the full strength of the wood is to be utilised; the colouring principle in fresh Brazil wood exists in the form of brazilin, which of itself has little colour; but by oxidation it is converted into brazilein, which possesses strong colouring power; this change occurs when decoctions of the wood are allowed to stand for some time. When the decoction is ready there is added to it 11⁄2 lbs. of alum, lb. of tin chloride solution, and then sufficient carbonate of soda to precipitate. The precipitate is collected, washed, and dried. Another method is to prepare a decoction as before, and to add to this sufficient freshly-precipitated alumina and oxide of tin.

A variety of Brazil-wood lake, which is known as Vienna lake, is prepared by mixing 60 lbs. of starch, 20 lbs. of chalk, and 2 lbs. of gypsum with a decoction of Brazil wood; then 2 lbs. of ground alum are added, and the mixture stirred, and allowed to stand for 12 hours; the liquor, which will be fairly free from colour, is decanted off, fresh alum and decoction of Brazil wood added, and the stirring, standing, &c., repeated; this operation is continued until the lake has acquired the desired shade. first the tone is inclined to be violet-red, owing to the alkalinity due to the chalk; but as this becomes neutralised by the successive additions of alum, the tint becomes crimson.

At

ROSE PINK is a crude kind of lake of a dull rose-red colour prepared from Brazil wood by making a decoction of the wood in the usual manner, adding some gypsum and chalk, and then precipitating with alum.

RED LAKE.-In a patent taken out in 1856, Gatty describes a process for making a red lake from Brazil wood by adding to 20 gallons of a decoction (sp. gr. 7° Tw.) 1 gallon of antimony chloride at 52° Tw.; filtering, washing, and drying the precipitate.

Messrs. Roberts & Dale patented in 1857 a process of preparing a red lake from barwood. 7 cwts. of barwood are boiled in 500 to 600 gallons of water, and 50 lbs. persulphate of tin diluted with water added thereto; the whole is boiled for 3 to 4 hours, allowed to settle, and decanted; the lake formed is washed, filtered, and dried.

* When exposed to light and air, crimson lake fades rapidly; in 14 days it will have faded about one-fourth, in 60 days to about one-half its original depth; after which it becomes more durable and fades but little.

Barwood is not adapted for preparing lakes, as the colouring principle it contains is not soluble in water, and the tin required to produce the lake must be added to the wood directly; as a consequence, the lake so prepared is apt to be contaminated with particles of the wood.

Another method described in the same patent is to boil barwood in a solution of 1 to 1 oz. of carbonate of soda per gallon of water, whereby the colouring principle is extracted; to the decoction (after straining off the wood) is added sufficient tin chloride to precipitate the lake.

YELLOW LAKES.-Dutch Pink, English Pink, and Italian Pink, are inappropriate names given to lakes of rather a crude kind prepared from quercitron bark. They can be prepared by boiling 2 lbs. of quercitron bark, straining the decoction, and adding 1 lb. of alum; to the mixture is added 4 lbs. of fine Paris white in small quantities at a time; then the mass is placed on one side for 2 or 3 hours, collected, washed, and dried. By decreasing the quantity of Paris white, the shade of the yellow is made deeper. Lakes from quercitron are used in painting theatrical scenery, as they do not lose much of their tint under the influence of gas light.

Another method is to use lb. of fustic extract, and 2 lbs. of gypsum, and to precipitate with 2 lb. of lead acetate.

YELLOW LAKE.-This is prepared from Persian berries by (a) boiling 1 lb. of the berries with 1 oz. of cream of tartar in 1 gallon of water, straining, and to the clear decoction adding sufficient alum to precipitate the lake. (b) 1 lb. of the berries is boiled with 1 lb. of alum in water; the liquor is strained, and then sufficient carbonate of potash is added to precipitate the lake; care is taken to avoid an excess of the alkali, as this would redissolve the colouring matter. (c) A cheap yellow lake, much employed in painting scenery, is made by boiling 2 lbs. of Persian berries with 2 lbs. of turmeric in water for some time, then, after straining the decoction, adding to it 1 lbs. of sulphate of alumina and 6 lbs. Paris white, allowing the mass to stand for some time, filtering, washing, and drying.

(d) Gatty's Process.--To 20 gallons of a decoction of quercitron (7° to 8° Tw.) is added 1 gallon of antimony chloride at 52° Tw. The lake is precipitated, washed, and dried.

ORANGE-CARMINE or ORANGE-LAKE.-1 lb. of Persian berries are boiled in 1 gallon of water and the liquor strained; then lb. of muriate of tin (commercial stannous chloride solution) added and sufficient sodium carbonate to precipitate the lake, which is collected, washed, and dried. This