18© 



Dr. J. BOTTOMLEY OH 



Column A contains the quantities of gas given off ; column 

 B has been formed by subtracting 649 from all the succeeding 

 numbers in the corresponding column in the first table ; it 

 shows the time which has elapsed. The total volume of 

 hydrogen which the sphere could furnish by dissolution, 

 at the commencement of the observations recorded in the 

 second table, will be 1145 — 200 cc. ; that is, 945 cc. In a 

 former part of the paper the following expression was 

 obtained for the radius {x) of a dissolving sphere at time t: 



This formula may be adapted to the present case as follows. 

 Let H be the equivalent in hydrogen of the mass of the 

 sphere at any time, H^ the equivalent of the initial mass ; 

 then we may derive the equations 



3 3 



d denoting density and n a constant 

 we may write the equation in the form 



Ho 



k denoting a constant. If h denote the hydrogen already 

 given off, the last equation may be changed into 



Substituting in (26) 



H 



t{i^^-\ 



