3i6

DYEING AND CALICO PRINTING.

obtained a brevet d'invention* for an application of an improved extract ofmadder, and Messrs. Girardin and Grelley made successful experiments on theapplication of their ammoniacal solution of colorin thickened with gum.After steaming the cloth so treated had only to be washed in cold water.This process had the additional advantage of being applicable to fabrics thegrounds of which had been dyed black by means of logwood, or brown bymeans of catechu, both of which colours do not stand the clearing process.None of these trials and experiments ever came really into general pra&ice,and only as late as the year 1855 was introduced what is known asM. Hartmann’s method, which has been used to a limited extent by the firmof Schwartz-Huguenin at Mulhouse, although this method has been entirelysuperseded by another invention due to M. Pernod.

We record here the manner of its execution according to the statements ofM. Al. Rack. The cloth is mordanted with acetate of alumina, first, by beingpassed through a solution of that salt at 1-022 sp. gr.; next dried, aged at ordinaryatmospheric temperature for twelve hours, cleansed by means of silicate of soda,and further proper treatment, and next dried, after which comes a secondmordanting in a bath of acetate of alumina at 1-036 sp. gr., followed by thesame cleansing and other operations. The colouring matter (an alcoholicextract of madder) used to be incorporated with soap solution, but since theso-called green alizarin was discovered, this latter substance in the state ofundried paste, and containing from 60 to 70 per cent of water, has been sub-stituted for this extratt.

The dried green alizarin can also be employed for this purpose, after havingbeen previously mixed (in the proportion of 65 parts of soda solution and 35 ofalizarin) with a solution of caustic soda at 1-007 sp. gr.f When the undriedpasty green alizarin is used there are added to 1 litre of this material 250grms.of gum, previously reduced to powder. This mixture keeps well. For thepurpose of colour printing the following mixture is employed :—1 litre ofthickened alizarin ; 0-4 litre of warm soap lye, prepared with 100 grnis. ofsoap to the litre ; 1 litre of gum water. This mixture has to be applied atonce, because it is liable to be spoiled by the coagulation of the soap. Some-times, also, this mixture is diluted by taking 1 kilo, thereof, and mixing thiswith 1 kilo, of a thickening fluid consisting of 4 litres of gum water and 1 litreof hot soap solution containing 100 grms. of soap ; or, again, 1 kilo, of thealizarin mixture with 1250 grms. of the thickener. After the printing anddrying the cloth is steamed for two hours, next washed with clean cold water,in a running stream if possible, and next soaped at a temperature of 20°. Ifrequired a cold and weak bleaching-powder bath may be applied.

The purpurin and yellow alizarin discovered by M. Kopp may be employedfor colour printing purposes by being first dissolved in weak caustic sodasolution, next thickened and printed on to properly mordanted fabrics, and,lastly, steamed.

As regards the printing of madder lakes and the fixing thereof on cloth

* “ Technologie de la Garance,” par M. Girardin (at present Doyen de la Faculte des Sciencesat Lille), Paris, 1844.

t This amounts to a quantity of less than 1 per cent of dry caustic soda, since, according tothe tables collocated by Dr. Gerlach (see “ Chemical News,” vol. xxi., p. 155), the sp. gr. of anaqueous solution of that alkali at 15 0 equal to roi 2 holds exactly 1 per cunt of the dry substance-