Nitric Acid and Ammonia in Rain- Water. 621 



The nitric acid of the thunder-rain is certainly very high, but, 

 as will be seen shortly, it is not very much greater than the 

 water of rnist and fog, and we are hardly justified in considering 

 these results as corroborating the theoretical explanation of the 

 production of nitric acid by electrical action. 

 September 2. — Thunder-rain — 



Nitric acid 0-035 



October 22. — Frost, mist, fog, &c. — 



Nitric acid O'OTl 



October 27. — Fog, mist, &c, — 



Nitric acid 0-071 



October 28. — Fog and mist — 



Nitric acid 0-089 



October 30. — Fog, mist, and little rain — 



Nitric acid 0-088 



November 27. — Snow which fell on the 26th, melted, and 

 collected with rain on the 27th, large total fall — 



Nitric acid 0-053 



Ammonia 0-654 



The quantity of ammonia in snow is here seen to be com- 

 paratively very large, a circumstance which has been repeatedly 

 observed, and which was confirmed by the late experiments of 

 M. Boussingault. 



December 5, a.m. — Snow which fell on the 2nd and 3rd, 

 melted, collected with rain on the 5th, moderate fall — 

 Nitric acid 0-0461 



December 5, p.m. — Little rain, very misty all day — 

 Nitric acid 0-053 



It appears to me that all that we can legitimately conclude 

 from these results is, that neither in the case of nitric acid nor 

 ammonia is the quantity present in the air sensibly increased by 

 such influences as electricity, heat, vScc. ; for so far as the water of 

 rain is concerned these compounds of nitrogen are evidently 

 inversely proportionate to the quantity of water falling. In the 

 cases of thunder-rain, the fall being slight, we have a large pro- 

 portion of nitric acid, although even then not much greater than 

 is found in the water of fogs and mists where the influence of 

 heat or electricity is not supposed. Where, however, a fair 

 quantity of rain falls accompanied with tliunder, we find only the 

 average proportion of nitric acid. The refreshing influence on 

 vegetation of a thunder-shower is due to the much-needed water 

 as water, and not to its being a vehicle of nitrogenous manure. 



VOL. xvir. 2 r 



