Allkn — Absorption of Water by Vulcanized Fibre and Erinoid. 407 



weight after 400 hours' immersion in nearly saturated air was respectively 

 12'8, 5'2, and 4"8 for red fibre, red erinoid, and blue erinoid. 



It is also seen from the curves 1 that the power of absorption is by no 

 means exhausted after 400 hours' immersion, and gradually a much higher 

 percentage increase of weight will be attained as time proceeds. 



160 loo ivo 



Time of immersion in hours. 



Fig. 1. 



The relation between the quantity of water absorbed from moist air and the time 

 of immersion therein. 

 Curve A is for red fibre, B for red erinoid, and C for blue erinoid. 

 The samples are of sheet form. 



Three samples in the form of tubes, each closed at one end, were similarly 

 tested, after having been dried for fourteen days at 70 = C. The humidity of 

 the moist air was practically the same as in the preceding test. The results 



1 The relation between x the grammes of water absorbed, and T the time of absorption 

 in hours, for the range of the experiment, will be found to be roughly represented by 

 x = JcT ' 6 , fc being 0'04 for red erinoid, 0-034 for blue erinoid, and 0-103 for red fibre. 

 This equation is not quite so representative for fibre as for erinoid, and this is probably 

 due to the greater sensitiveness of the former material to any small change in the degree 

 of humidity of the air-bath. 



