182 



KEPORT 1865. 



Table III. 

 Third Series of Experiments on Absorption at ordinary temperatures 



Reduced results. 



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 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 supe- 

 riority 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 tempe- 

 rature on the absorption of water by these insulators. 



The different substances were tried separately, as in the first series, and the 

 weighings were repeated at intervals. During the night it was necessary to remove 

 the gas-jet, as the uniformity of temperature could not be depended upon; hence 

 for half the period of immersion the specimens were at a temperature of 50° only, 

 and for the remainder at a temperature of 100°. The loss of weight after removal 



Table IV. 



Fourth Series of Experiments on Absorption at increased temperatures. 



Reduced results. 



