&76 



Presents. 



f June 20, 



Mond and Langer. 



Nature of aeration plate 

 surface, platinum black. 

 Strength of acid, not 

 stated. 



Alder Wright and Thompson. 



Platinum black. 



Platinum sponge. 



10H 2 SO 4 ,100H 2 O. 



10H 2 SO 4 ,100H 2 O. 



2-5H 2 SO 4 ,100fl 2 O. 



Zinc .... 

 Cadmium 

 Copper . . 



1-77 volt. 

 1 425 „ 

 0-70 „ 



1 -750 volt. 

 1 -505 „ 

 -780 „ 



1 -628 volt. 

 1 -383 „ 

 0-658 „ 



1 -681 volt. 

 1-356 „ 

 -636 „ 



Similarly, in attributing the diminution of the E.M.F. of gas 

 batteries below the calculated amount to the circumstance that heat 

 is evolved during the condensation of gases on surfaces like spongy 

 metals, the authors appear to have been unacquainted with numerous 

 previous papers by one of us, and more especially with one published 

 in 1881, in which this and various allied matters were pretty fully 

 discussed,* and the conclusion arrived at (inter alia), that " the heats 

 of condensation of oxygen and hydrogen by platinum, &c, may 

 jointly amount to almost as large a quantity as that developed by 

 their union to form liquid water." — July 30th, 1889.] 



XVIII. "On certain Geometrical Theorems. No. 4." By 

 W. H. L. Russell, A.B., F.R.S. Received May 25, 1889. 



[Publication deferred.] 



XIX. " An Experimental Verification of the Sine Law of 

 Malus." By E. J. Spitta. Communicated by W. DE W. 

 Abney, Capt. R.E., F.R.S. Received May 29, 1889. 



XX. " Observations on the Spark Discharge." By J. Jolt. 

 Communicated by Professor Gr. F. Fitzgerald, F.R.S. 

 Received June 15, 1889. 



[Publication deferred.] 

 Presents, June 20, 1889. 



Transactions. 



Baltimore : — Johns Hopkins University. Circular. Vol. VIII. 

 No. 73. 4to. Baltimore 1889. The University. 



* No. Ill of a series of nine Memoirs on the " Determination of Chemical Affinity 

 in terms of Electromotive Force." ' Proceedings of the Physical Society,' vol. 4, 

 p. 101 ; also « Phil. Mag.,' March, 1881 (Series 5, vol. 77, p." 169). 



