Experimental and Applied 293 



according to the conditions of growth and the methods of 

 separating and preparing the fibre. The greater proportion, 

 being pectose-like substances, are easily attacked by alkaline 

 hydrolysis ; but the removal of a large weight of such products 

 from a mass of cloth is not an easy operation. The alkaline 

 treatments are therefore graduated, and are three or even four 

 times repeated before the cloth is considered ready for the 

 bleaching treatment. There are then the additional complica- 

 tions of the wood residue (sprit) and cuticular constituents 

 which very much protract the after processes, or bleaching 

 proper. These processes may be divided into series, the first 

 of each series being the process of treating with dilute solu- 

 tions of the hypochlorites. These involve prolonged exposures 

 (6-12 hours), the cloth being entirely submerged in the solution. 

 After this follows usually the souring process, and to this 

 succeeds a light boil in progressively weaker alkaline solutions. 

 These treatments, with intermediate washings, constitute the 

 'round.' After each round, the cloth, or rather the residue of 

 non-cellulose constituents, is in the most favourable condition 

 for the further attack of the oxidising or bleaching agent. 

 These processes are repeated until the impurities are finally 

 eliminated. In addition to these treatments, which are those 

 practised by the cotton bleacher, linen undergoes the process 

 of 'grassing,' i.e. is spread out upon grassfields and exposed 

 for one or two days to the action of light and air and the other 

 influences of the ' weather.' This process follows an alkaline 

 treatment of the cloth, whether in the earlier or later stages, 

 when the cloth is in the most favourable condition for the 

 action of the atmospheric oxygen. The linen is also treated 

 by a special process of mechanical rubbing with a strong soap 

 solution. 



The complications of the process are such that the full linen 

 bleach takes from three to six weeks to accomplish. They 



