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DYEING AND CALICO PRINTING.

whether the required shade has been reached, several bits of waste materialof a similar kind are tacked on to the goods being dyed. From time to timeone of these is taken off, rinsed in water, steeped for a moment in dilute acidin order to try the shade. The accompanying specimen of Nicholson’sblue (4 B) we owe to the courtesy of the firm of Brooke, Simpson, andSpiller.

Guernsey blue is a very permanent colour, and is frequently applied upon aground of cam-wood or santal-wood, in order to produce a cheap and perma-nent shade resembling a vat-blue.

ANILINE GREENS.

Usebe Green, Cherpin Green, Emeraldine, Night Green, Rosaline Green,Emerald-Green, Aldehyde Green, Iodine Green, Ethyl-rosaniline Green,Picrate of Ethyl-rosaniline, Sexethyl-rosaniline, Iodide of Ethyl Green,Pomona Green, &c.

The earliest aniline green introduced was the emeraldine of Messrs. Lowe,Clift, and Calvert, which was not prepared as a separate dye, but produced onthe fibre. To print with this colour, 500 grms. of chlorate of potash weredissolved, with the aid of heat, in 25 to 30 grms. of starch liquor. When themixture was cool, rj kilos, of the acid chloride of aniline (or of one of itshomologues), containing 500 grms. of aniline, was carefully incorporated. Thecolour was developed by exposing the printed goods to the air for twelve toeighteen hours. The process has now merely a historical interest.

Iodine Green, or Bimethyl-Iodhydrate of Trimethylic Rosaniline.

This is obtained, in greater or less quantity, in the preparation of Hofmann’sviolet. Tillmanns, Meister Lucius, and Briining, all made more or less suc-cessful attempts at its manufacture in 1865. In the same year Wanklynpatented a process for its production, which became the starting-point for thepresent successful methods.

It is now manufactured in air-tight vessels of enamelled iron, of the capacityof 80 to 100 litres, and capable of bearing a pressure of 23 atmospheres.They are heated by means of a steam-jacket (Fig. 20). As the greenbegins to decompose at no 0 C., it is necessary to know exactly the tempera-ture of the steam circulating in the steam-jacket, which is therefore fittedwith a pressure-gauge. In the head of the vessel is adapted another, to indi-cate the pressure existing in the interior of the apparatus. There is also ascrew-tap, by which, at any given moment, the excess of the reagentsemployed, or of the liquid products of the reaction, may be distilled off. Theingredients used are—

10 kilos, of pure acetate of rosaniline ;

20 ,, pure iodide of methyl;

20 „ methylic alcohol, boiling at 64° to 70° C.

Steam is now turned on, taking care that during the whole operation thepressure in the steam-jacket may not exceed 1 atmosphere. In the interior ofthe boiler the pressure rises rapidly to 8 atmospheres, and then more graduallyto 10 or 11, which it must not be allowed to exceed. The process lasts fourto five hours. At the expiration of that time the steam is turned off, and theapparatus allowed to cool. The pressure falls by degrees, and after twelve