PRINTING STUFFS OF WOOL AND SILK, AND STUFFS WITH COTTON WARPS. This branch of our subject is directly allied to the one last considered, the application of the compounds of sulphur and indigo; for indigo is applied to printing wool and silk principally in the form of indigo carmines. These applications are less numerous than they were formerly, since they have been replaced by Prussian blue, and more recently by the aniline blues, which are now generally used. When the carmines are used, it is for making sky blues, and they enter into the composition of some greens and browns. The salts of alumina and vegetable acids are used to fix the indigo carmine upon tissues of wool and silk. Some receipts recommended by M. de Kæppelin, himself a practical printer, are given in a note.[7] ------------------------------------------------------------- [7] BLUE NO. 1. Indigo carmine 400 grammes. Alum 100 „ Oxalic acid 150 „ Boiling water 1¼ litre Gum water prepared in proportion of 1 kilogram to the litre 1¼ litre GREEN NO. 1. Gum water as above 12 litres. Cuba lac 12 „ Alum 1 kilogram, 500 grammes. Oxalic acid 2 „ Indigo carmine 4 „ BOUILLON FOR THE GREENS AND BLUES. Boiling water 12 litres. Alum 600 grammes. Oxalic acid 750 „ Gum water 12 „ SKY BLUE FOR WOOLLEN STUFF WITH COTTON WARP. First solution.—Boiling water 4 litres. Cyanuret of iron and potash 800 grammes. Second solution.—Boiling water 2 „ Tartaric acid 300 „ Third solution.—Cold water 3 „ Sulphuric acid 300 „ Pour in the first solution, then the second and third, agitating the color with a spatula after each new addition. The following mixture is afterwards applied to the stuff:— Gum water 12 litres. Water 6 „ Blue No. 1 for wool 3 „ ------------------------------------------------------------- In printing tissues of wool with cotton warp, the carmines are not used alone. They are combined in certain proportions with cyanites of iron and potash, to obtain upon the cotton a blue color of equal intensity with that produced by the carmines upon wool. It is also necessary to previously mordant the fabrics by means of a solution of oxide of tin or caustic soda which is precipitated on the fibres by passing through a bath of water, to which sulphuric acid has been added.