OF ARTS AND SCIENCES. 81 



TABLE XVIII. 

 Electrodes, Carbon, Carbon. 

 Normal Pressure in Grams. Excursion of Hammer at Critical Point. 



0.207 8 X 10-^ 



0.032 12 X 10-6 



0.990 12 X 10-« 



1.288 12 X 10-6 



1.650 25 X 10-« 



2.150 25 X 10-6 



Electrodes, Carbon, Platinum. 



Normal Pressure in Grams. Excursion of Hammer at Critical Point. 



0.184 8 X 10-6 



0.288 12 X 10-6 



0.482 12 X 10-6 



0.632 12 X 10-6 



0.990 12 X 10-6 



1.288 12 X 10-6 



1.654 Anvil vibrating. 



0.104 >8 X 10-^ 



0.132 >8 X 10-« 



0.153 8 X 10-6 



0.184 8 X 10-6 



0.288 12 X 10-6 



0.632 12 X 10-6 



0.990 12 X 10-6 



0.180 8 X 10-6 



0.395 12 X 10-6 



0.620 12 X 10-6 



0.644 12 X 10-6 



0.149 8 X 10-6 



It appears from these results, that the value of the excursion corre- 

 sponding to the critical point rises with increase of normal pressure, 

 soon attaining a maximum and constant value. The pressure at which 

 this maximum value was reached was greatest when both electrodes 

 were of platinum, and least when the hammer electrode was of plati- 

 num and the anvil of carbon. When both electrodes were of carbon, 



VOL. XXV. (n. s. xvti.) 6 



