USES OF CASEIN IN THE TEXTILE INDUSTRY. 123 



formaldehyde. The resulting insoluble compound of the 

 latter substance and size or casein, envelops the colouring 

 matter, and thus fixes it, waterproof, on the fibre. The 

 printing colour, prepared with dissolved size or casein, is 

 treated with the ammonia or bisulphite compound of for- 

 maldehyde and printed on the fabric. This printing colour 

 does not coagulate at ordinary temperature, and it is only 

 when the printed fabric has been steamed or heated that the 

 formaldehyde compound is decomposed, and the liberated 

 formaldehyde combines with the size or casein to form an 

 insoluble compound. This method has been patented and 

 used in Great Britain. In another system the printing col- 

 our is prepared with casein, and the printed and steamed 

 fabric is exposed to the action of formaldehyde. 



WATERPROOFING AND SOFTENING DRESSING. 



The finishing of textile fabrics has hitherto consisted in 

 impregnating them with a soluble dressing and then drying 

 them, the dressing thereupon solidifying on the fibre and 

 making the material more or less stiff. This system, however, 

 is attended with the defect that when the fabrics are moistened 

 the stiffness soon disappears owing to the solubility of the 

 dressing. The defect in question can now be obviated by 

 impregnating the fabric with a soluble mass that is capable 

 of conversion into an insoluble form by means of chemical 

 or physical agents. According to a process patented in 

 France, the fabric is treated in the cold with a mixture of 

 casein, albumen or gelatine, and formaldehyde or hexamethy- 

 lenamine, then dried at 80 C., and finely steamed. The 

 solution of the colloidal substance may also be incorporated 

 with pigments or loading ingredients, such as barium sul- 

 phate, these being fixed on the fibre when the albumen is 

 hardened by the formaldehyde. Casein and gelatine are 

 used as 10 per cent, solutions ; and the aqueous solution 



