388 On the Compressibility of Solids 



about 35 cm. and 85 cm. from the seat of the explosion. 

 ^v The bursting pressure in this case was no 

 / ^ ]\ more than 150 atmospheres, yet the effect 

 produced was very much greater than it 

 was in the case of copper. 



The experiments with gold and alu- 

 minium were carried out without the loss 

 of a terminal. 



In the case of platinum, a terminal 

 burst at about 250 atmospheres, but it 

 produced no apparent seismic effect. ( )n 

 the last day of my experiments I proposed 

 to determine the compressibility of a wire 

 of mild steel, but, owing to hurry in putting 

 the apparatus together, it was impossible 

 to get any satisfactory observations, but 

 one of the terminals burst, and at a 

 pressure over 250 atmospheres. Here 

 again there was no seismic effect. The 

 platinum wire had been thoroughly an- 

 nealed before being used, and the mild 

 steel wire was as soft and ductile as 

 copper, yet, though copper showed the 

 seismic effect beautifully, it was imper- 

 ceptible in both platinum and steel. Before 

 the experiment with the steel, I supposed 

 that the high density of platinum caused 

 the shock to be opposed by more inertia 

 than it could overcome, but the density 

 of steel is less than that of copper, there- 

 fore its immunity to shock must be due 

 to something other than its density. 



The open ends of the glass terminals 

 which are inside of the watertight collars 

 are cut sharply off and the edges are not 

 rounded in the flame. Special directions 

 were given to the glass blower about this, 

 because the effect of it would be the 



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