122 CASEIN. 



The casein must be free from any acid impurities. 



The materials to be treated are immersed in a bath prepared 

 by swelling casein in an aqueous solution of glycerine, lactic 

 acid, dye and, if necessary, loading ingredients being also 

 present. Ten parts of powdered casein are mixed with 50 

 of water and a solution of 2 parts of glycerine (30 B.) in 

 100 of water, *the necessary dye and loading ingredients 

 being added when the casein is thoroughly swollen. This 

 casein bath may be acidified with 2 to 4 per cent, of lactic 

 acid, without producing any precipitation of the casein itself. 

 By means of this bath it is possible to finish and dye fabrics 

 in an acid liquid, which was previously impracticable with 

 alkaline solutions of casein. 



FIXING CASEIN' AND OTHER ALBUMINOIDS ON THE FIBRE, 

 MORE PARTICULARLY IN DYEING. 



Vegetable fibres, e.g., cotton, jute or liax, are steeped 

 with a solution of casein in hydrochloric acid, phosphoric 

 acid, or lactic acid, and treated with a saline solution like 

 sodium sulphate, ferric acetate, sodium bichromate or sodium 

 tungstate, capable of throwing down from the casein solution 

 a precipitate that is insoluble in water. For instance, 10 

 parts of casein are dissolved in 200 of water and 1 part of 25 

 per cent, hydrochloric acid. The cotton is steeped in this 

 solution, and, after the excess liquor has been removed by 

 squeezing, is passed through a warm 10 per cent, solution 

 of Glauber salt, and then washed. The hydrochloric acid 

 may be replaced by an equal amount of 25 per cent, phos- 

 phoric acid, the material being afterwards treated with ferric 

 acetate and washed (German patent 139,565). 



FIXING INSOLUBLE COLOURING MATTERS. 



The colours to be fixed are printed with size or casein, 

 the fabric being then steamed or treated with a solution of 



