SECTIONAL TRANSACTIONS.- TEXTILES. 117 



favourably situated, with respect to climatic conditions for cotton growing, than the 

 majority of the new areas, where the penalty for the long-staple bias is the more 

 serious. 



The long-staple bias has hitherto had the support of the scientific plant breeders, 

 who have held that staple quality is independent of climatic limitations and that, 

 given the necessary experimental facilities in hybridisation and selection, the finer 

 staples are producible in any area. After many hundreds of experiments the world 

 over, and covering over twenty years of work, the results do not uphold their con- 

 tention ; and it is apparent that they are subject to the same climatic limitations that 

 restricted the possible lines of development to the old plant breeders. 



A change in staple policy to one that is sensitive to natural limitations is, therefore, 

 urged as conducive to the best interests of the cotton trade and to the security of the 

 glowers in the new areas. 



Dr. Barr and Miss Hadfield. — Nature of the Action of Sunlight on Cotton. 



Mr. F. T. Peirce. — Problems of Textile Testing : (a) Variability ; (b) Time 

 Effects. 



Tuesday, September 6. 



Mr. A. L. Wykes. — Quantitative Determination of the Physical Properties of 

 Artificial Sill- and their Relationship to Textile Manufacture. 



After outlining the method of making artificial silk, it is shown that success in 

 weaving, knitting, and braiding depends on a proper understanding of the physical 

 properties of the yarn concerned. In the main, the numerous troubles met with in 

 the manufacture of fabrics are due to the treating of artificial silk as if it were a 

 simple substance, while, in fact, it is a complex of two substances with different 

 physical properties. The two are described hi this paper as ' locked ' cellulose and 

 ' dispersed ' cellulose, and the general properties with load-extension and elasticity 

 curves are described for each form. It is pointed out that these two substances are 

 contained in ordinary viscose artificial silk in varying proportions, and that it is easy 

 to convert one form into the other with consequent modification of the characteristics 

 of the yarn. The effect of friction on an artificial silk thread is shown. 



Common weaving and knitting faults are explained with reference to the theory 

 advanced. Finally, recent improvements of commercial artificial silk are noted, and 

 suggestions are made for its future development. 



Mr. J. A. Matthew. — Extensibility of Flax Yarns. 



A review is made of the work which has been done on the extensibility of flax yarns. 

 •The different experimental methods are described, and compared. The characteristics 

 of stretch-load diagrams for flax yarns are described, and the methods of quantitative 

 expression of these characteristics used by New and by the author are detailed and 

 compared. The latter are concluded to be preferable since they cover the former 

 with a fewer number of figures, the behaviour over the whole diagram is represented 

 and the results from yarns of different sizes are directty comparable. 



A method of analysis is described, based on the detection of irregular manu- 



Total (yt) 



facturing conditions by means of the value of the ratio p ermanen t stretch — . lhe 



vt 

 characteristics of the diagram are expressed by the values - ; Young's Modulus of 



Elasticity of the yarn (E) ; the equation to the total stretch-load curve >j,= 



1 % t 



a,x-\- , log ln — where y, = total stretch recorded on the diagram due to a load 



X ounces. 



x,= initial tension on the yarn in ounces. 



x t =x+x i .; and a factor .K which may be determined by measurement whence 



E may be calculated for any desired conditions from the relation 

 e 



E = 16.4 (JC-1) K {a,+ lA , *< )where A '=2". The ratio y < is a measure 

 A' b t x x ' y„ y„ 



of the effects of tensions experienced by the yam before testing, and the effect on the 



1927 E E 



