C.

the oxidation of the braziline. By the addition of a small quantity of chlorate of potash to the hot extract, Mr. Peak greatly increased its briliancy, and rendered it more valuable to the printer on account of the brighter colour produced on the fabric.

These extracts are principally used to obtain pinks and reds in steam styles. To effect this, acetate of alumina, chloride of tin, oxalic acid, or acetate of cop-per is added to the extract, and printed on the prepared cloth already described, which is then submitted to the action of steam.

These woods are also used in conjunction with a little quercitron, or bark, in the production of cheap garan-cine styles. These inferior garancine prints are easily distinguished from the good ones by means of a hot soap-bath, which only slightly affects the good, while the inferior are almost entirely destroyed. The woods also are sometimes used for the adultération of garancine.

I may state, beforeleaving this subject, that the décoction of these woods yield very beautiful pink lakes, which are principally used. by paper-stainers.

Common red-ink is also prepared by adding a little alum and acid to an aqueous solution of these woods.

Sandal, Cam, and Bar Woods.—The next class of dye-stuffs which we shall have the pleasure of studying together are derived from several varieties of the genus Pterocarpus, which are indigenous to the trv; wal parts of both the new and the old world. It is principally from the East Indies, Ceylon, Madagascar, and the coast of Malabar, that santal, sandal, or red sanders wood is imported, whilst cam and bar woods are pro-cured from Sierra Leone.

The colour-giving principle of this class of plants is only developed with age, the young branches not contain-ing any, whilst it is found in large quantifies in the trunk. Professor Bolley proved that it is the same colour-giving principle which exists in each variety, and he gave it the name of santaline. MM. Wagermann and Haeffely con-sider that it has the formula C1:H14Os. It is a bright red crystalline powder, insoluble in water, but soluble in alcohol, ether, and acetic acid. The latter solvent yields the colouring matter to albumen, which is an important fact, and may one day be rendered practically useful. Santaline is freely soluble in alkalies, giving a violet-red solution, from which acids precipitate the colouring matter.

Sandal-wood is chiefly used on the Continent, where it is employed to give a bottom* to cloth which is to be àfterwards dyed with indigo. By this process a very fine blue is produced, having a purple hue by reflected light.

Cam-wood, and especially bar-wood, is chiefly used in England for producing on cotton-yarns brilliant orange-red colours, known as mock Turkey-reds. They are, however, neither so fast nor so bright as the real Turkey-red produced from madder, and are easily distinguished from it by yielding their colour to a hot soap solution, or to alkalies.

Alkanet.—The root of the Anchusa tinctoria contains a beautiful red resinous principle, to which Professor Bolley assigns the formula C35 H40 O8, which is insoluble in water but soluble in alcohol, ether, and bi-sulphuret of carbon. To all these solvents it com-municates a fine purple colour, which becomes blue on the addition of an alkali. It is not at the présent day employed as a dyestuff, its chief uses being in pharmacy to colour medicines ; in perfumery, to colour oils and greases ; and in domestic life to give a tint to the lime-wash used for the walls of private dwellings.

Safflower.—Although this dye-stuf has lost much of its value sincethe discovery oftho aniline colours,it is still extensively used in Lancashire for the production of peculiar shades of pinks for the eastern markets. It is

* This term is used in dyeing, to dénoté that a colour is applied to a fabric with a view of giving a peçuliarhue to a dye which is applied after it.

also used for dyeing red tape, and I know no more striking instance of red-tapeism than the love which is shown for this particular dye by the users of this article. Much cheaper pinks can be produced from aniline, and, notwithstanding that many times the attempt has been made to introduce them, it has in every instance failed, because the exact shade bas not been attained.

Safflower is the bloom of a peculiar thistle called Car-thamus tinctorius, which is cultivated in France, Egypt, Spain, Italy, and India. In France and Spain, the small flowers ‘composing the heads of the thistle are picked of and dried in the shade, whilst in Egypt and India they are squeezed, washed with cold water to remove useless materials, slightly pressed into lumps, and dried in the shade ; the latter have about double the value of the former. The safflower so prepared only contains three to six parts per thousand of the colour-giving principle.

This principle has received the name of carthamic acid, and has the formula C14 H. 6 014. A solution of this acid, when dried on a polished white surface, leaves a varnish, having a beautiful red colour, by transmitted light, whilst it assumes the the irridescence of cantharides when seen by reflected light. It is insoluble in water and ether, but soluble in alcohol. This solution becomes yellow on the addition of sulphuric, nitric, or hydro-chloric acid. It is also turned yellow or orange by weak alkalies, and the colouring matter in this latter solution, undergoes rapid alteration if exposed to the atmosphère. It is owing to the fugitive nature of the colour, and its easy modification by acid and ammoniacal vapours, that the délicate pinks produced from safflower havebeen so successfully replaced by the pink aniline dyes.

To préparé carthamic acid, safflower is introduced into bags and washed, till a yellow colouring matter which it contains is removed. It is then mixed with water, to which is added 15 per cent, of the weight of safflower taken of crystalised carbonate of soda. After two hours macération, the liquor is run off, and cotton yarn dipped in; then lemon juice or citric acid is added to liberate the carthamic acid, which fixes itself on the yarn. Up to this point, the process is the same as that adoptod in dyeing fabrics, but to obtain the acid, it is necessary to treat the washed cotton a second time with carbonate of soda, which dissolves out the carthamic acid, leaving a second yellow colouring matter fixed on the cloth. The carthamato of soda thus obtained is de-composed by tartaric acid, and the carthamic acid falls as a brilliant red amorphous powder, which, when mixed with a little water, is sold as safflower extract, and when dry and mixed with ground-talc, is employed as rouge by ladies.

There is a particular extract extensively used in dyeing, the préparation of which is a secret. Its value dépends on the fact that the carthamic acid is rendered soluble in water.

Cochineal, Kermes, Lac-dye, and Murexide.—I shall now call your attention to four colours derived from the animal kingdom, namely, cochineal, kermes, lac-dye, and murexide.

The first three are distinct species of a peculiar tribe of insects called Coccina. The females, from which alone the colouring-matter is derived, form a mass nearly destituto of limbs, and romain attached to one spot on the plants infested by them. The males, on the contrary, are very minute and really élégant créatures, furnished with a single pair of filmy wings. The real cochineal is called Coccus cacti; kermes, Coccus illicis ; and lac-dye, Coceus lacca or ficus. They all contain the saine colouring principle. Although the dyes derived from some species of these insects were well-known to the ancients, and were much used in Persia and India, the true cochineal has only been known in Europe since the discovery of America by the Spaniards ; and since the year 1830 only has it been propagated in the Canary Islande, the island of Teneriffe, Java, and Algiers. The best qualities are still obtained from the republic of Honduras.

The Coccus cacti lives on a species of cactus called the

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