DISSOLVED MATTER CONTAINED IN RAIN WATER. 145 



The results of 1887 in the above table as regards nitrogen are 

 somewhat abnormal. The proportion existing as ammonia is less 

 than that of the other years, wliile that in the form of nitric acid 

 is higher. As before stated, the specimens were somewhat old 

 before being analysed, and it might with justice be assumed that 

 nitriticatioh of the ammonia had taken place and that much of it 

 had been converted into nitric acid. The condition under which 

 the samples wei'e stored as regards light were favourable to nitri- 

 fication, the room facing south and being not very well lighted. 

 Messrs. Lawes, Gilbert, and Warrington, in their experiments, 

 found that with the rain-water collected at Rothanisted that the 

 ammonia in rain-water was fairly permanent, but it is also 

 suggested that this might be due to lead in solution derived from 

 the guage in which it was collected, this being detrimental to the 

 existence of the organisms by which nitrification is effected. 

 Experiments have been started with a view to ascei'taining 

 whether nitrification does take place in the Lincoln rain-water, 

 and at what rate it proceeds. If the ammonia has become nitrified 

 it will not aftect the results of the total nitrogen, but only its 

 condition. If we consider the ratio existing between the ammonia 

 and nitric acid in the rain of the several yeai's the difference of 

 composition is very apparent. In the following table in which 

 the results have been computed from the quantity of nitrogen as 

 ammonia and nitric acid received annually in lbs. per acre of land, 

 the ratio existing between the niti'ogen in the two substances is 

 shewn. 



Table III. — Shewing ratio between the nitrogen 

 and nitric acid contained in rain-water. 



Year N as NH3 



1884 1 — 



1885 1 — 



1886 1 — 



1887 1 — 



1888 (to June) ... 1 — 



The differences is also evident from the table of curves appenc 

 to this paper. 



The results contained in the table of analyses shew the propor- 

 tion of the several constituents per 1,000,000 parts of rain, and 

 the means shew merely the average composition, assuming that 

 this amount of each monthly rainfall were taken. But the rain- 

 fall of each month varies and the amount of dissolved matter 

 varies with it, but in an inverse ratio, and consequently the 

 results will be better understood when the absolute quantity of 

 the several constituents received over a given area are calculated. 

 From the numbers so obtained the real average composition of 

 the water can be deduced. 



