HOFMANN VIOLET.

613

Hofmann Violet on Calico.

The colour is mixed with red liquor, and with a solution of arsenious acidin water to which some glycerin has been added, as diredted on p. 207. Boththese compounds together form the mordant. After steaming for an hour it isgently soaped. The colour is thickened with gum and starch.

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Hofmann Violet.

Delaines.

The method of printing delaines, and other mixed fabrics composed ofwool, or worsted, with a cotton warp, may be treated as an appendix to thesteam style. The preparation of the goods is different, and in most casesthe colours are mixed differently, so as to be suitable both for the cotton andwool. The steaming and subsequent operations are very similar to thoserecommended for calico. The first step is the bleaching of the goods, whichis exceedingly important, and which is performed by means of the fumes ofburning sulphur. For this purpose they are hung up in a close brick or stonechamber, and sulphur, being placed upon the floor in iron dishes, is set fire to,and the door is tightly closed. After the lapse of some hours the pieces aretaken out and washed. The following improved apparatus (Figs. 37 and 38)is the invention of Mr. John Thom.

A (Fig 37) represents the roof of the chamber, made of sheet-lead, of 4 lbs.to the square foot. B is a lead pipe, of 1 inch diameter, to carry off any excessof sulphurous gas. c c are rolls of pieces, to enter the chamber at one sideand come out at the other, d d are wooden cylinders, turning on iron axles.ee represents the. flooring, made of perforated tiles, similar to the floor of amalt-kiln, through which the sulphurous acid gas enters.

Fig. 38 represents the sulphur-chamber, 6 feet long by 4 broad and 5 high,fitted with two windows, placed opposite to each other, f is an iron tray in