350 Mr. E. J. Mills on the Chemical Activity of Nitrates. [May 19, 



a 



2 



Q 



O / 0 



2oo*30 



3029 



K . 1 Q 



o 4o 



1 09'94 



31-01 



o 1/ 



loo 00 



or>.nr» 



32'02 





14/ 4U 



o 1*9,3 



z 21 



195*01 



8824 



1-99 



101-14 



50-82 



170 



85-05 



50-03 



1-61 



G9-00 



42-86 



The above list probably contains all the metallic nitrates that can be 

 completely dried, excepting nitrates derived from amines and amides, 

 which, in the present state of our knowledge of the phosphamides, it was 

 evidently advisable to exclude. 



In the silver group, the mean value of Q is 31*11 ; and the following 

 equation may be accepted therefore : — 



2 



a= 3TTT- 



In the potassium group we have likewise 



50 42 



Hence, within each set of nitrates, chemical activity is in direct propor- 

 tion to symbolic value. It is further sufficiently apparent that (excepting 

 rubidic nitrate) a and 2 increase and diminish in the same general order. 

 Within the limits of error, the Q column is an incomplete arithmetical 

 series, the most probable value of whose first term is G-258, so that 



Q=« 6-258, 



m being integral. Reasons are then adduced for identifying the number 

 6'25 with Dulong and Petit's constant of specific heat. Moreover, since 

 the product of specific heat and symbolic value is, generally, n 6 -25, and 

 m is greater than n i taking m—xn and s=the specific heat of a nitrate, we 

 have Q=xn 6'25, 



but Zs = n 6-25 ; 



Q=.vZ*, 



2 _ 2 _ 1 



the expression for chemical activity in terms of specific heat. Comparing the 

 coefficients (o,a') for any two nitrates, the followingrelations are obtained: — 



a m' 2 :c's 



a'~~m ' 2 ,— x* ' 



and it is shown that these formulae agree sufficiently well with experiment. 

 "Where m = m* and .r=.r', we have the simple expression 



a _2 _s 

 a 2' * 



