Allen — Absorption of Water by Vulcanized Fibre and Erinoid. 409 



is smaller than the ratio of the areas. This divergence of erinoid from the 

 case of fibre is probably due to different processes being employed in the 

 manufacture of the plate and tubular forms. 



110 160 100 



Time of immersion in hours. 



Fig. 2. 



Absorption of water and time of immersion in moist air. 



Curve A is for red fibre, B for red erinoid, and Cfor black erinoid. 



The samples are of tubular form. 



Change of electrical resistance due to the vjater absorbed by fibre and 

 erinoid from moist air. 



The sample, in the form of a tube closed at one end, was thoroughly dried 

 by heating for fourteen days in an air-oven at 70° C. Its electrical resistance 

 was then measured, and directly afterwards the sample was placed in nearly 

 saturated air for a certain time, and its resistance again determined. This 

 was repeated for a number of succeeding intervals. 



The readings of the two thermometers of the hygrometer were roughly 

 constant through all the following tests, the average difference between them 

 being 0'4° C, and the average temperature indicated by the dry bulb 

 thermometer 18-5° 0. 



A set of resistances for different temperatures was measured after each 

 interval of immersion in the moist air. During the test a slight loss of 



