Wright. — Absorption of Moisture by Wools. 



221 



The amount of moisture absorbed by pure wool-fibre free from incrusta- 

 tions and adhering impurities was determined, and the results are shown 

 as follows : — 



Table V. — Pure Wool-fibre. 



It is thus seen that pure wool-fibre, free from all other matters, absorbs 

 from 18-0.3 to 19-62 per cent, of moisture from the atmosphere under varying 

 degrees of humidity. 



It is obvious from the above results that the pure wool-fibre cannot be 

 the only matter in normal wool which causes the absorption of moisture, 

 for in the greasy wool, containing from 50 to 60 per cent, of pure wool-fibre, 

 it is found that the absorption of moisture is from 24 to 29 per cent., 

 whereas if the pure wool-fibre were the only factor we should expect to find 

 a moisture-absorption of but from 9 to 12 per cent. ; and in slipe wool, con- 

 taining from 70 to 80 per cent, pure wool-fibre, we find a moisture absorption 

 of from 16 to 20 per cent., whereas it should be only from 14 to 15 per cent. 

 It is thus apparent that there are other factors which determine the amount 

 of moisture absorbed. 



It is probable that the relatively high amounts of moisture absorbed by 

 pure wool-fibre is due to the very large surface-area presented to the atmo- 

 sphere in proportion to the weight of the fibre. 



A number of wool-fibres, each 3 in. long, were counted and weighed, and 

 the following results calculated : 13,100 fibres of half-bred wool, each 3 in. 

 long, weighs 1 gram ; 12,500 fibres of three-quarter-bred, each 3 in. long, 

 weighs 1 gram ; 9,100 fibres of Leicester, each 3 in. long, weighs 1 gram ; 

 7,800 fibres of Lincoln, each 3 in. long, weighs 1 gram. 



If we take the average diameter of each of the above classes of wool as 

 given in the following table, it will be found by calculation that the surface- 

 area of 1 gram of wool is as follows : — 



Diameter. 

 Half-bred .. .. .. 0-0008 in. 



Three-quarter-bred . . . . 0-0010 in. 



Leicester . . . . . . 0-0016 in. 



Lincoln . . . . . . 0-0018 in. 



Surface-area of 1 Gram. 



98 sq. in. 



118 sq. in. 



136 sq. in. 



132 sq. in. 



It will be seen that the large surface-area is an important factor in con- 

 sidering the relatively large amount of moisture absorbed by the fibre. 



The wool-fat was examined, and it was found capable of absorbing up 

 to 17-2 per cent, moisture when spread thinly on a watch-glass; but even 

 with the inclusion of this factor it is not possible to account for more than 

 1 or 2 per cent, of the moisture absorbed by the normal wool-fibre. 



