634 Original Articles. | Oct., 
Taste W1—Third Series of Experiments on Absorption, at Ordinary Temperatures. 
Reduction of results to 10 inches area. 
23 A . |ee8 |ee, z B | 
BS : ged |S e Ses |ooo less 
eS E INSULATORS, Bae |Se Sail 28 isk: 5S 
6 Raw india-rubber . . . 15,000 6.54 450 10 1:65 
7 Masticated india-rubber . | 15,000 | 6°54 | 450]! 10 | 0-22). 
8 5) « 1 15,000} 6°54), 4505 eto 0-293 
9 De 9 . | 155000) |) 6-54 | 450) | TO) Os3s0 
10 Carbonized india-rubber. | 15,000 | 6°54 | 450} 10 | 0°29 
5) Gutta-perchay . . . . | 15,000 |) G:d4 | 450 | 10 | 0-18 
1 Wray’s compound. . . | 15,000 | 6:54 | 450); 10 eae 
2 ; o 8) 6 15,000 6°54 450 10 0-58) S5 
3 Chatterton’s compound . | 15,000 | 6°54} 450] 10 0-054 [1S 
4 ” » . | 15,000] 6:54 | 450} 10 | 0-058/= 
The temperature during these experiments was generally lower 
than in the second series, being frequently at the freezing-point. There 
was loose ice in the cylinder when opened. 
The higher pressures in these experiments seem to bring out more 
decisively the differences in the amount of absorption ; but it is remark- 
able that, whilst the relative absorption does not widely differ, and the 
order of the insulators in their resistance to absorption 1s the same, 
the absolute quantity absorbed under greater pressure is less than in 
the previous series of experiments. The only discrepancy between 
the two series of experiments is the relatively low absorption of 
masticated india-rubber. 
The order of merit, or power of resisting absorption, is in these 
experiments— 
1. Chatterton’s compound. 
2. Gutta-percha. 
3. Masticated india-rubber. 
4. Carbonized india-rubber. 
5, Wray’s compound. 
6. Raw india-rubber. 
The last in this series absorbed twenty-seven times as much as the 
first; gutta-percha and Chatterton’s compound hold, as before, the 
highest place, but the superiority of the latter was more manifest ; it 
had become whitened at the surface, but apparently the water had 
penetrated the thinnest possible film. 
The next experiments were made with a view to determine 
the effect of temperature on the absorption of water by these in- 
