92 



TEXTILE FIBRES. 



up a spun yarn have the property of swelling out, and acquire a glossiness 

 that causes the yarn to have a silky appearance. Material so treated is 

 known in the trade as mercerised fibres arid yarns. The swelling of 

 the fibres causes a shrinkage in length ; the fibres are more transparent, 

 and gain something in strength and in weight; their capability for 

 taking up certain dyes is increased, particularly the dyestuffs of the 

 "Congo Red" group. 



Fig. 65 shows the pearly-white and silky lustre or gloss of a lea 

 of 2/60s mercerised yarn. At first the process of mercerising had the 



Fig. 65. Mercerised yarn. 



effect of causing some shrinkage, but recently this difficulty has been 

 overcome, as was the case in the example shown in the .illustration. 



Fig. 66 shows the yarn from the same hank spread out to the 

 best advantage for allowing the fullest amount of light to fall on 

 the yarn hank crossings. For these samples of mercerised yarns I 

 am indebted to Mr. Geo. H. Hurst, F.C.S., of Manchester. When 

 mercerised yarns are magnified under the microscope, the inter- 

 spaces in the screw line of the twist are well marked, and the fibres 

 of the yarn spread out from the marginal surface and allow the light 

 to penetrate. Very recently a company has been floated for carrying 

 out the process as applied to finishing of mercerised yarns. The 

 demand for these yarns has grown considerably ; they have been keen 



