1892.] Formation and Decomposition of Nitrous Acid. 4i) 



increasing in geometrical as the latter increases in arithmetical pro- 

 portion. This relation may be expressed by the equation 



v t = vk-'J, 



that is to say, the difference of the logarithms of the amounts of 

 nitrous acid decomposed at the end of a given interval of time will be 

 constant for a constant difference of temperature. This is rendered 

 evident by the following comparison : 



Percentage loss 

 after 270. 



24-00 



Series. 



(i) 



(ii) 



(in) 



Temp. 

 11-2 



27-7 

 31-2 



43-01 

 49-09 



Logarithms. 



1-3802 

 1-6334 

 1-6909 



The logarithmic differences for 1 are therefore : 



From (I) and (III) 0-0153 



(I) (II) 0-0154 



(II) (HI) 0-0167 , /% 



Mean 0'0158 



The rate of chemical decomposition of the nitrous acid is therefore 

 practically doubled for every 20, which would give a constant 

 logarithmic difference of 0"0151 for every degree. In this respect 

 this change resembles another, otherwise totally different from it, 

 namely, that between marble and hydrochloric acid,* which varies by 

 a like amount for equal differences of temperature. This relation is 

 also exemplified by another pair of experiments in which 20 c.c. of 

 nitric acid through which nitric oxide gas had been passed were 

 made with water up to a constant volume of 100 c.c. 



Series XXX. 



Volume of solution = 100 c.c. Temperature, 21-8. 

 Ratio of nitrous to nitric acid = 1 : 10'2. 



* Spring, ' Zeit. Physikal Chem.,' vol. 1, p. 219. 



VOL. til. 



