On the Seat of the Electromotive Forces in a Voltaic Cell, 51 













... 

 Carbon bi- 



Pressure. 



dp 



dt' 



t. 



dp 

 dt 



Water made 

 = 1-000 



sulphide 



made = 



1000 



millim. 





o 









10 



0-350 



4573 



160 



0-866 





50 



1-405 



5085 



714 



0-850 



1057 



100 



2-506 



534-2 



1339 



0-833 



1046 



150 



3-54 



550-97 



1950 



0843 



1-061 



200 



4-47 



563-44 



2519 



0835 



1-061 



300 



6-25 



582-21 



3639 



0-834 



1-061 



400 



7-85 



59644 



4682 



0-827 



1-055 



500 



9-40 



608-03 



5715 



0-827 



1-055 



600 



1091 



61787 



6741 



0-829 



1060 



700 



12-34 



62648 



7731 



0-824 



1-057 



800 



1375 



634-0 



8717 



0-829 



1-059 



900 



15-01 



641-0 



9621 



0-814 



1-037 



1000 



16-37 



6472 



10595 



0-818 



1-049 



1500 



22-38 



673-1 



15064 



0-811 



1-038 



2000 



28-33 



6930 



19633 



0-816 



1-064 



3000 



38-61 



723-1 



27919 



0-804 



1071 



5000 



56-90 



7656 



43562 



0-800 



1059 



It will be seen that the agreement with carbon bisulphide is 

 extremely close throughout, and that with water the variation 

 is not greater than with some of the other substances examined. 



The variations from constancy in the reduced values of ~ . t 

 will be considered in Part III. 



dt 



Note. — Reference has been made to the vapour-pressures of 

 alcohol at high and low temperatures determined by ourselves. 

 The data are contained in a paper presented to the Royal 

 Society in May 1885. The vapour-pressures of dissociable 

 substances are given in a paper read before the Royal Society 

 in November 1885. Neither of these papers is as yet 

 published. 



VIII. Some Notes by Professors Ayrton, F.R.S., and John 

 Perry, F.E.S., on Dr. Lodge's Paper on The Seat of the 

 Electromotive Forces in a Voltaic Cell "*. 



THE value of the historical part of Dr. Lodge's paper can 

 hardly be overrated. A fair share of credit has been 

 given in it to all experimenters on Contact Forces, and his 

 description of the different kinds of apparatus used by the 

 various investigators is very clear and very helpful, but we cer- 

 tainly object to the unproved assumption running all through 



* Communicated by the Authors. 

 E 2 



