408 



Scientific Proceedings, Royal Dublin Society. 



which were obtained are given in Table 2, and the corresponding graphs in 

 Fig. 2. 



Table 2. 



W is the initial weight after drying, A the surface area of the sample 

 exposed to the moist air, and x the quantity of absorbed water in grammes 

 The time of exposure is given in hours. 



As the superficial area of the fibre-tube is much larger than that of either 

 of the erinoid tubes, the quantity of water absorbed by it will be correspond- 

 ingly greater. Curve A, Fig. 2, is therefore much higher than it would be if 

 its area was 155 instead of 275 sq. cms. 



On comparing the results of the plate sample of fibre with that of the 

 tubular sample of the same material, for a given time of immersion, it will be 

 found that the ratio of the respective quantities of water absorbed is roughly 

 constant. Thus, from the curves of Figs. 1 and 2, it follows that this ratio 

 for 40 hours' immersion is 3-9 ; for 80 hours' immersion 4 ; and for 160 

 hours' immersion also 4. The forms of the two absorption-curves are there- 

 fore practically the same. The ratio of the exposed surfaces of the two 



275 

 samples, namely, -— ^ = 3'6, is somewhat smaller than the preceding ratio. 



The corresponding ratio of the quantities of absorbed water in the case 

 of the tubular and plate samples of red erinoid is not quite so constant, and 



