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The diffculty and expense experienced by calico-printers in brightening their colours, and obtaining pure whites in madder-dyed goods, attracted many years ago the attention of scientific and practical men, and any process by which these difficulties might be overcome was anxiously looked for. The discovery of MM. Robiquet and Collins, that the colour-giving principle was not destroyed by sulphuric acid, was the step in that direction, and led M. E. Schwartz to observe that the carbonaceous mass of Robiquet, if carefully washed and neutralised, could be used as a dye-stuff. MM. Lagier and Thomas improved upon this, and introduced, in 1839, an article which is now extensively used by calico printers and named garancine, and now is prepared as follows : — Madder, either unwashed, or, better still, washed with cold water, is mixed with one-third of its weight of sulphuric acid, which has been previously diluted with water till it marks 10° Twaddle ; it is then boiled for four or five hours, and the mixture run on to woollen filters, and washed till only a mere trace of acid remains. It is then either removed or washed once with a very weak solution of carbonate of soda, submitted to hydraulic pressure, and then introduced into drying stoves. One hundred parts of madder yield from 34 to 37 of garancine. Garancine is a fine powder of a light brown colour, and has a dyeing power four times as great as the original madder. It does not give as good blacks as madder, nor are its purple, red, and pink so fast, but its purple is brighter, and the whites are obtained pure without soaping, it being only necessary to substitute a slight clearing liquor, com-posed of an alkaline, hypochlorite of soda, to which is added a small portion of sulphate of zinc.

In 1852, Messrs. Pinckoff and Schunck effected an im-provement in the manufacture of garancine, their pro-duct being known in England under the name of commercial alizarine; but on the Continent it is better known as Pincoffine. Their process consists in submitting ordi-nary garancine to the action of high pressure steam of a température of 300° F., which, whilst it does not act on the alizarine contained in the garancine, destroys two other colouring matters which are présent. These Dr. Schunck has isolated and examined, and named Puber-tine and Perantine. They are of a peculiar resinous nature, and spoil both the whites and the purples, which are fixed along with alizarine in the dyeing process. The employment of commercial alizarine is especially advantageous in the production of purples, which are faster and more brilliant than those produced by ordinary garancine. The cloth also does not require either soaping or cleansing.

M. Pernod has, within the last two or three years, introduced a madder extract, which is at the présent time extensively used in Lancashire as a topical colour. This term is applied to a colour which is printed on a fabric, and afterwards fixed by steaming. By this method bright and fast colours are introduced in printed goods, producing much more effective designs than could be effected if the goods had to pass through a dyc-beck and afterwards be washed with large quantifies of water. Some splendid specimens of this class of printing were to be seen at the last Universal Exhi-tion, 1867.

To prépare the extract, garancine is lixiviated till completely exhausted, with a nearly boiling solution of sulphuric acid, containing five parts of acid to a thou-sand of water. On cooling, an orange red prccipitate falls to the bottom of the vessel, which, when collected and thoroughly washed, constitutes an extract ready for use. The products of M. Leitonberger and Messrs. Schaaffer and Lauth may be substituted for this ex-tract.

As the employment of these extracts is the most important improvement recently introduced into calico printing, I will give the three following recipes for their application:—To produce dark red, take 8 Ibs. of extract of madder, 41bs. acetic acid, and l{ lbs. starch.

Boil these in an earthenware vessel, and when cold add to six measures of the above one of acetate of alumina and a very small quantity of Gallipoli oil, say 1 per cent. For a pale red, take 4 Ibs. of extract of madder, 2 Ibs. of acetic acid, 10 quarts of gum Sénégal water, and I pint of acetate of alumina. To obtain a purple, take I pint of extract of madder, half pint of acetic acid, half pint of water, and 3 ozs. starch; boil, and when the mixture is cool, 5 ozs. measure of acetate of iron of 24° Twaddle, and 5 ozs. of water. To produce a chocolaté, proceed as in the last recipe, substi-tuting acetate of chrome for the acetate of iron.

The above mixtures are printed on cloth by means of engraved copper rollers, and are then dried and submitted to dry high-pressure steam for one or two hours, when the colours have become fixed on the fabric. After being slightly soaped, to remove all excess of colour, the prints are stiffened, and ready for the market.

Although I have now concluded my lecture on madder as a dye-stuff, and have already exceeded the time allotted to me, I hope you will allow me a few minutes more, to enable me to give an outline of the processes by which madder styles are produced, the more so as there may be some persons présent who are not aware how madder and garancine prints, now manufactured in such enormous quantities and in such general use, are produced.

To effect this, the ordinary white calico, as sold in shops, is not sufficiently deprived of its impurities to be employed in madder or garancine styles ; it has therefore to undergo further bleaching operations. The calico so extra bleached is then printed by means of copper rollers, on which the pattern to be produced is engraved. This roller leaves on the calico a red, purple, or chocolaté mordant ; that is, for red, a sulpho-acetate of alumina, or red mordant ; for purples, violets, and blacks, an impure acetate of protoxide of iron, known in the trade as pyrolignite of iron, or black liquor ; and for chocolatés a mixture of these two mordants.

After this operation the pièces undergo a process technically termed ageing. This was formerly effected by spreading out the pièces, and hanging them in a room for three or four days, so that the acetate of alumina might lose part of its acetic acid, and the iron mordant nearly the whole of it, thus liberating the oxide of iron and enabling it to undergo partial oxidation.

Some fèw years ago, Mr. David Thom introduced a process by which this is effected in twenty minutes; it consists in passing the printed mordanted cloth over rollers fixed in a machine placed in a chamber about twenty feet long, in which a current of air and steam is thrown. The température of this chamber must not be below 100° nor above 108°, and the quantity of steam présent must be such that fifty yards of calico will take up one ounce of moisture during the twenty minutes it takes to pass through the chamber. The printer is able to test the state of the chamber by means of wet and dry bulb thermometers. The next operation to whi h the cloth is submitted is dunging. The process re-ceived this name because formerly the calico was passed through a mixture of cow-dungwith water. Now, however, silicates or arseniates of soda, mixed with a little chlorate of potash, are substituted. After passing through either of these solutions they are washed, and ready to be passed through the dye-beck. This beck contains water, and from five to seven pounds of madder, or one to two and a half pounds of garancine, or commercial alizarine, foreach pieceofcalicoto bedyed. The heatofthe bath is then gradually raised, by means of a jet of steam, to 180° for garancines, or 212° for madders. This operation takes from one and a-half to two hours, accord-ing to class of goods, style, &c. The fabrics are then washed and passed through a cleansing liquor for garancine or commercial alizarine styles, or soaped twice at 180° when they are dyed with madder.

The most permanent and brilliant colour produced from the rubia plant on cotton fabrics is Turkey red.

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