COLOURS ON WOOLLENS.

To each piece of fabric dissolve I lb. of hyposulphite of soda in 2 pails ofwater, to which add 1 lb. of sulphuric acid, the vessel containing the mixturebeing well covered, so as not to lose any sulphurous acid gas. All the sulphurmust be allowed to settle until the liquid is clear, and the liquid may then berun into a clean tub filled with water. In this bath the goods are to be laidfor 6 to 8 hours, when the whites will be found perfectly bleached withoutinjury to the black. Rinse, and dry.

COLOURS ON WOOLLENS—BLUES.

Woad.

Woad alone was used for colouring wool blue before indigo was intro-duced into Europe. The introduction of indigo was a great advantage tothe dyer, not only for its intrinsic value, but because he could daily strengthenhis vat, using the old woad as a fermenting agent, like yeast in making bread.As to the practical value of the different varieties of indigo, it may be said that4 lbs. of good Bengal are equivalent to 5 lbs. of good Guatemala indigo.

In order to colour with indigo we have to deprive it of its oxygen. The de-oxidised indigo is yellow, and in this state penetrates the woollen fibre; themore perfectly the indigo in a vat is deoxidised, the brighter and faster willbe the colour.

To a vat 8 feet deep by 6 feet wide, filled with water, and heated by steam orotherwise to 140° F., add 200 lbs. of woad, about 10 lbs of well-ground indigo,—or more, according to the amount of work to be done,—5 lbs. of soda, i a bushelof good wheat-bran, 10 lbs. of good madder, and 1 lb. of flour. If the soda,bran, madder, and flour are boiled for five minutes before adding them to thevat, it will ferment twelve hours earlier than it would otherwise do. Stir thevat well, and after eight hours’ rest again stir. The vat by this time shouldhave commenced to ferment, the liquid acquiring a mottled appearance. Whenthe fermentation is well established, add about 2 lbs. of slaked lime, and againstir. If sufficient lime has been added, the surface of the vat will reflect agolden colour; and a sample of wool immersed in the liquid for about twentyminutes should become perfectly coloured blue in one minute. A green colourremaining with the wool after one minute shows that more lime must beadded. Should this addition be neglected, the vat will be, as it is termedtechnically, “ lost.” The lime added should be mixed with water, andthe solution filtered. A vat, to which too much lime has been added, orwhich has become “ over-sharpened,” acquires a brown colour, and the woolimmersed in the liquor is imperfectly coloured a grey-blue. 2 or 3 lbs. ofsulphuric acid may be added in such a case to form with the lime a neutralsulphate, which settles to the bottom of the vat. After the addition of thesulphuric acid a mixture of 5 lbs. of bran and 3 lbs. of madder boiled togethershould be added. Fermentation is thus again set up, and can be reduced bylime as before. When the vat is exhausted ; and more indigo must be added,care should be taken that the liquor is sharp enough. The liquor should againbe warmed, and the indigo added with about 6 lbs. of madder, 6 lbs. of bran,and 2 lbs. of soda, boiled together as beforfi. The indigo should be addedover-night, in order that fermentation may be complete by the morning. Inthe morning lime must be added until the golden film forms on the. surface ofthe liquid.