160 BRAZILIAN COTTON 



Since the statistics thus obtained would be meaningless without 

 some basis of comparison, we have put beside them similar figures 

 taken from our records to show the kind of results given by good 

 cottons from America and Egypt. 



(1) The average of a dozen well-grown medium staple American 

 Upland samples. 



(2) A long staple but rather coarse Brown Egyptian of strain 

 No. 77. 



(3) A high grade extra Sakel cotton. 



(4) Three other pure strains of Egyptian, No. 310 being a super- 

 Sakel, while Nos. 95 and 111 more resemble Assili. 



The statistical tests applied were as follows : — 



<A) HAIR BREAK 



These tests show the average results obtained by breaking 100 

 hairs at random, the length of each portion of hair tested being 1cm. 

 taken in the middle of the hair. Results are expressed in grammes, 

 und give some clue to the strength which may be expected in the yarn, 

 provided that the yarns compared are all of equal regularity. 



To effect this comparison for the same count, we have to take 

 into consideration the hair break of equivalent weights of cotton. 

 This has been indicated under the heading of " Relative Hair Break," 

 which expresses the strength as shown by hairs of equal hair weight 

 <D), i.e., equal fineness. 



(B) WALL THICKNESS 



The thickness of the cell wall of the hair is measured in 100 hairs 

 indirectly by taking the difference between the total width of the hair 

 at some one point of the width, and the width of the central canal, 

 this difference being divided by two to give the thickness of the wall. 



(C) RIBBON WIDTH 



We use this term for what is commonly and inaccurately described 

 as the diameter of the hair. It is determined at the same time as the 

 measurements of wall thickness. 



Cross Sectional Area. This can be calculated, if required, 

 irom the figures for wall thickness and Ribbon Width. It mainly 

 ioUows the hair weight. 



tD) HAIR WEIGHT 



A known length of hair is taken from the middle of each of a 

 large numbers of hairs, and from the total weight of all these separate 

 lengths we compute the average weight of a single centimetre of hair. 

 Results are expressed in milligrammes per centimetre. 



This test is one of the measurements of fineness, and from it can 

 be calculated the number of hairs in cross section of any given kind 

 of yarn. The lower the hair weight the more hairs there will be in 



