II. 



THE ATMOSPHEKE 



27 



maximum amount being 16-25 (4-2 parts of nitrogen) and the mini- 

 mum 0-2 parts (0'05 nitrogen) per million. In the island of Reunion an 

 average of 2-67 parts per million of nitric acid (equal to O69 parts of 

 nitrogen) was found. As the rainfall, too, is much greater, it is obvious 

 that the amount of nitric nitrogen conveyed to the soil by the rain is 

 very much greater in the tropics than in England. 



The same authors in 1890 1 found a mean of 1-55 milligrams of 

 ammonia (= 1-28 mgm. of nitrogen) per litre in rain-water collected in 

 the tropics. Here, too, the amount is much greater than in England. 



Many analyses of rain-water in various parts of the world have been 

 published in recent years. The following table gives some of the 

 results : 



The amounts of nitrogen in the rain collected in Pretoria and at 

 Garforth were probably higher than exists in that of the neighbour- 

 ing open country, being affected by the proximity of towns. This is 

 indicated by the large amount of sulphates and free sulphuric acid 

 present in the rain at Garforth (mean for two years, 11-67 parts total 

 SO 3 per million, equivalent to about 73 Ib. S0 3 per acre), which, being 

 about seven miles to the east of Leeds, is doubtless affected by the pro- 

 ducts of combustion of coal carried by the prevailing westerly winds. 



For a discussion and summary of results obtained by the examina- 



iCompt. Rend., 114, 184. 

 3 Ibid. 1906, Abstracts, ii. 302. 

 r >Ibid. 1910, Abstracts, ii. 647. 

 7 Ibid. 1909, Abstracts, ii. 429. 



2 Jour. Chem. Soc., 1906, Abstracts, ii. 302. 

 *Ibid. 1910, Abstracts, ii. 444. 

 6 Ibid. 1909, Abstracts, ii. 340. 

 *Jbid. 1911, Abstracts, ii. 327. 



