This lake is prepared in fair quantities and sold under such names as Signal Red, Imperial Red, &c.

From alpha-naphthylamine may be prepared in a similar manner a fine crimson red lake. 14 lbs. of alpha-naphthylamine are gently heated with 30 lbs. of hydrochloric acid and 20 gallons of water until completely dissolved. The solution is then slowly poured into 30 gallons of water. The beta-naphthylamine will be precipitated as hydrochloride in the form of a fine white or faintly coloured precipitate. This is of no moment provided it be fine and not lumpy in character. The mixture must be allowed to become quite cold before passing on to the next stage. A solution of 10 lbs. of sodium nitrite in 10 gallons of cold water is made, and then poured into the alpha-naphthylamine mixture, the whole being kept constantly stirred for from one-half to three-quarters of an hour, when the operation will be ended. There is next added 30 lbs. of sodium acetate dissolved in 25 gallons of water, and 150 lbs. of barytes. To this mass is added slowly a solution of 14 lbs. beta-naphthol in 4 lbs. of caustic soda and 30 gallons of water. The lake forms at once, and is washed, filtered, and dried in the usual manner.

ORANGE LAKES.-Any of the azo- or acid oranges may be used to make lakes by any of the methods described under the reds. The following are three recipes for making orange lakes:—

1. 100 lbs. of base, 5 lbs. of orange G, 5 lbs. of barium chloride. 2. 100 lbs. of base, 3 lbs. of croceine orange, 4 lbs. of barium chloride, used according to the first method.

3. 62 lbs. of Glauber's salt, 10 lbs. of orange G, 70 lbs. of barium chloride, used according to method 3.

YELLOW LAKES.-The following recipes show the method of making yellow lakes from some of the azo- and acid yellows:1. 100 lbs. of base, 3 lbs. of yellow N, 10 lbs. of lead acetate. 2. 100 lbs. of base, 3 lbs. of Indian yellow, 5 lbs. of barium chloride, used according to method 1.

3. 62 lbs. of Glauber's salt, 10 lbs. of Indian yellow, and 70 Ibs. of barium chloride, used according to method 3.

BLUE LAKES.-1. 100 lbs. of base, 2 lbs. of Victoria blue R, 5 lbs. of barium chloride.

2. 100 lbs. of base, 2 lbs. of alkaline blue, 5 lbs. of barium chloride.

3. 100 lbs. of base, 3 lbs. of alkaline blue, 4 lbs. of lead acetate. There are many shades of alkaline blue, ranging from a very red shade 4R, to a very blue shade 6B, so that a great variety of tints or shades of lakes can be made; the proportions of colouring matter and precipitant given are only approximate.

and necessarily they will vary with the kind and make of alkaline blue used.

These recipes are used according to method 1, given under the red lakes.

4. 62 lbs. of Glauber's salt, 2 lbs. of alkaline blue, 70 lbs. of barium chloride, used according to method 3, described under red lakes.

BROWN LAKES.-1. 100 lbs. of base, 3 lbs. of orchil brown B, 6 lbs. of barium chloride.

2. 100 lbs. of base, 10 lbs. of cotton brown A, 20 lbs. of barium chloride. Both used according to method 1.

3. 62 lbs. of Glauber's salt, 10 lbs. of cotton brown A, 85 lbs. of barium chloride, used according to method 3. This gives a dark reddish shade of brown lake.

VIOLET LAKES.—1. 100 lbs. of base, 3 lbs. of acid mauve B, 15 lbs. of barium chloride. This gives a red shade of violet lake. 2. 100 lbs. of base, 3 lbs. of acid violet 6B, 10 lbs. of barium chloride. This gives a blue shade of violet lake.

Like the alkaline blues and the basic violets, the acid violets are made in a variety of shades, from a red 3R to a blue 6B, so that quite a large range of violet lakes, from a red to a violet hue, can be made from the acid violets.

Both these recipes are to be used as described under method 1 of red lakes.

3. 62 lbs. of Glauber's salt, 2 lbs. of acid violet 3B, 72 lbs. of barium chloride, used according to the third method.

BLACK LAKE.-100 lbs. of base, 10 lbs. of naphthol black B, 15 lbs. of barium chloride. This gives a rather grey shade of black.

GREEN LAKE.-100 lbs. of base, 5 lbs. of naphthol green B, 40 lbs. of lead acetate; the addition of a little ammonia completes the precipitation; the lake obtained is of an olive-green shade.

It is obvious that, in all the above recipes for making lakes from the acid coal-tar colours, by varying the proportions between the base and the colouring matter, a great variety of tints can be obtained from the same dyestuff; still, it is advisable not to reduce the proportion of dyestuff too much or the resulting lake will have too chalky an appearance. In this connection it may be mentioned that barytes makes the best pale-tinted lakes; china clay cannot be used very satisfactorily for this purpose, as, unless a large proportion of dyestuff is used along with it, it is apt to make chalky-looking lake-pigments. Necessarily, if the proportion of dyestuff to base be reduced, the quantity of precipitant required will also be less; the quantities of these

given in all the above recipes should only be taken as approximate; each particular sample of dyestuff will take its own proportion of precipitant, and as the actual quality of a dyestuff varies with different makers, it is scarcely possible to give very exact proportions, unless, of course, the maker's name were inserted, and this it is not deemed desirable to do in this book.

LAKES FROM ADJECTIVE COAL-TAR COLOURING

MATTERS.

The third group of coal-tar colours are called the adjective or sometimes the mordant dyeing, dyestuffs, from the fact that, as already pointed out, they require the aid of a mordant, as it is called, to properly develop and fix the colour; in the most representative members of this group, alizarine, nitrosoresorcin, gambine, &c., the colour which is formed varies with the mordant used (see p. 260). Most, if not all, the dyestuff's which belong to this group possess acid properties, and have the property of combining with metallic oxides, like those of alumina, iron, chrome, tin, lead, &c., to form compounds which are more or less coloured, and quite insoluble in water; it is on this property that their value in dyeing, calico-printing, or in lake-making depends. In the two former arts the colour lake resulting from the combination of the dyestuff with the metallic oxide is formed on the fibre, while in the last it is formed in the free condition or on a base of some kind. The general principle which underlies the various processes for the preparation of lake pigments from this group of dyestuffs is that of bringing the dyestuff into contact with the oxide of the metal with which it is desired to combine it, and thus cause the colour lake to be formed.

The principal colouring matters of this group are alizarine and purpurine; these two bodies are sold under the general name of alizarine, which is made in several brands distinguished by letters, AB, SX, V, G, &c. Practically, there are two kinds of alizarine-alizarine yellow shade, which, with alumina, gives scarlet reds, and consists principally of alizarine; the other kind is the alizarine blue shade, which, with alumina, gives more crimson reds than the last, and consists mostly of purpurine. Then there are alizarine blue, alizarine yellow, alizarine cyanine, gallein, gallocyanine, galloflavine, nitrosoresorcin, gambine, &c.

ALIZĂRINE LAKES.-Various processes can be employed for converting alizarine into lakes.

1. Pure Alizarine Lake.—Mix 20 ozs. of ordinary commercial

alizarine* with 1 galls. of water; then add 10 ozs. of alumina sulphate previously dissolved in water, and 2 ozs. of calcium acetate dissolved in water; boil the whole together for about an hour; then add 10 ozs. of soda crystals dissolved in water in small quantities at a time, at intervals long enough to allow of the subsidence of the effervescence thus set up. The whole mass is now boiled for about an hour, then allowed to stand for 24 hours, filtered, washed, and dried. This makes a dark red lake of good body and staining power. upon the kind of alizarine used.

The shade or tint will depend Excess of soda crystals should

be avoided, as it causes the lake to be of a dark colour.

2. Dark Red Alizarine Lake Diffuse 100 lbs. of barytes through 50 gallons of water, add 20 lbs. of alizarine, 10 lbs. of alumina sulphate, and 2 parts of calcium acetate; stir well together, and then allow to stand for two or three hours, stirring at intervals to keep the ingredients well mixed. Heat slowly, so as to take about two hours to reach the boiling point, and, at intervals, add portions of a solution of 10 lbs. of soda crystals. Much of the beauty of the resulting lake depends on the care exercised during this stage of the process; too rapid heating, and too rapid addition of the soda crystals, has a tendency to cause the shade of the lake to be darker than it should be. The lake obtained by this process is of a fine ruby red colour. After it is formed, as described above, it is finished in the usual way.

3. Alizarine Lake.-Diffuse 100 lbs. of barytes through 50 gallons of water, add 10 lbs. of oleine or Turkey-red oil, and boil for one hour; allow to stand for twenty-four hours, stirring up at intervals, add 20 lbs. of alumina acetate (12° Tw.), and 2 lbs. of calcium acetate, stir all well together, and allow to stand for two days; then boil well for two hours, adding at the same time 5 lbs. of soda crystals. When the lake has formed, filter off, wash, and dry.

4. Alizarine Red Lake.—6 lbs. of alumina sulphate are dissolved in water, and to this solution one of 1 lb. of calcium chloride is added; a precipitate of calcium sulphate is obtained, but, before this has had time to settle out, a solution of 44 lbs. of soda crystals is added; the precipitate of alumina and calcium sulphate thus obtained is collected on a filter and washed. It is

* Nearly all the so-called alizarine colours are sold in the form of a paste, containing about 20 per cent. of actual colouring matter. The reason for this form is that, as a rule, these dyestuffs are insoluble in water, and it has been found by practical experience that if sold in a dry form that the dyestuff does not mix well with water, and that they thus give rise to uneven dyeing, while the paste form mixes very well with water, and uneven dyeing rarely occurs.

then introduced into a solution containing 3 lbs. of alizarine, 1 lb. of Turkey-red oil, and 1 oz. of tannic acid, and the mixture heated for half an hour to about 70° C., when it will be found that the alumina has taken up all the alizarine, and become dyed thereby. It is now boiled for one hour longer, and then finished in the usual way.

5. Alizarine Red Lake.-Muller Jacobs has patented, in Germany, the following process for making an alizarine lake:50 grammes of alizarine oil are dissolved in 1,400 cc. of water, 15 grammes of alizarine, and 0.2 grammes of tannic acid; the mixture is heated to boiling, when 60 cc. of a solution of alumina sulphate of 1·1014 (20-3° Tw.), specific gravity, which has been previously mixed with 22 per cent. of soda crystals, are added. The lake soon forms, especially on boiling for some time; it contains some oil which can be extracted with ether. The use of such a large proportion of oil is objectionable, as it makes the resulting lake very greasy, and prevents its use for certain purposes. Moreover, it is not practicable on a commercial scale, owing to the cost involved in extracting this excess of oil.

6. Alizarine Scarlet Lake.-A very fine lake is made in the following manner :-63 lbs. of alumina sulphate are dissolved in 20 gallons of water; to this is added the solution of 1 lb. of calcium chloride in one gallon of water, and immediately after a solution of 41 lbs. of soda ash dissolved in 10 gallons of water. A precipitate of alumina is obtained, mixed with some sulphate of calcium; this precipitate is collected and well washed. It is now diffused through 10 to 15 gallons of water, and there is added 3 lbs. of alizarine, 1 lb. of Turkey-red oil, and 1 oz. tannic acid, the mixture being heated to from 160° to 165° F. and kept at that heat for about half an hour, when 1⁄2 lb. more of Turkey-red oil is added. Then the whole mass is boiled for one hour, after which the lake is ready for washing and drying. It is important that the sulphate of alumina used be free from iron, and that, during the process of making, the materials be kept free from contact with that metal, or the colour of the lake will be deteriorated.

In making alizarine lakes it is important to use an alumina sulphate which is free from iron, as this latter ingredient has a great and deteriorating influence upon the colour of the resulting lake; very small traces of iron are sufficient to give a brown hue to the lake.

The methods of making lakes from alizarine, just described, are equally applicable to the preparation of lakes from the other alizarine dyestuffs.