APPENDIX, 



On the Ageing of Mordants in Calico Printing^ 

 By Waxter Cetjm, F.E.S. 



(Postponed Paper, Read to the Society December 14, 1859, vide p. 263.) 

 The process of " ageing" in calico printing is that by which a mordant, 

 after being applied to a cotton fabric, is placed in circumstances favoiar- 

 able to its being incorporated with and fixed in the fibre ; and the 

 method usually employed has been to suspend mordanted goods in an 

 apartment in single folds, exposed to the atmosphere. 



The object is to moisten the acetates of iron and of alumina in order 

 to their decomposition ; and, in ordinary circumstances, a pound of 

 water is gradually absorbed by fifteen pounds of printed cloth. The 

 protoacetate of iron is thus enabled, by imbibing oxygen, to become a 

 sesquiacetate like the bisalt of alumina. Each then proceeds to give 

 off acetic acid, and to deposit a tersesquihydrate upon the fibre, 



Vaiious methods have been employed in this country for adding 

 to the natural moisture of the air, but with no great advantage until 

 Mr. Jones introduced into Messrs. Schwabe's Works, near Manchester, 

 a system of ageing which he had seen in operation at Mulhausen, and 

 succeeded, by the direct introduction of steam undei-neath, greatly to 

 increase the heat and moisture of the large apartment in which his 

 mordanted goods were hung, and thus to render the process of ageing 

 not only more speedy, but much more perfect than before. But the 

 employment of steam was in that case limited in amount, chiefly by 

 the discomfort to which it subjected the workpeople in the apartment, 

 and by the damage produced by drops of water falling from their per- 

 sons upon the goods. 



In the summer of 1856, Mr. Jones visited ThornUebank, and 

 described that method of ageing. It became then not difficult to con- 

 ceive that, by a further increase of heat and moistm'e in an apartment 

 sufficiently capacious, and by employing a great number of rollers, 

 goods might become sufficiently moistened without manual labour, by 

 being merely passed through such an atmosphere ; and that thus, the 

 pieces being stitched end to end, a continuous process might be sub- 

 . stituted for that of hanging goods over wooden rails, and leaving them 

 there until the ageing is completed. 



The idea of passing printed goods through an atmosphere artificially 



