1 82 The Dissolution of an Isotropic Solid. 



of hydrogen corresponding to the initial strength of the acid, 

 // the volume of hydrogen corresponding to the acid con- 

 sumed ; then 7i denoting some constant quantity, we have 



H = ;7A, h = nQ, 

 substituting these values in their equation, writing / for 

 KSoAht^ we obtain the following differential equation : 



Integrating and determining the constant by the condition 

 // — 0, ^ = 0, we get the following equation : 



t = p{Hi-{U-m (27) 



The value of p determined by the condition t=S2 //= 50 is 

 465-9. By means of equation (27) the numbers in column 

 D in the last table have been derived. The divergence of 

 the observed and calculated times in the latter part of the 

 operation is very marked. Also solution ought to have 

 been completed in 4572 seconds, but according to the ex- 

 periment it was not completed in 6099 seconds, and even 

 then there remained 145 cc. of hydrogen to be evolved with 

 a rapidly diminishing velocity. 



