24 



AMMONIA 



the elevation and is greater in cloudy than in clear weather. 1 These 

 amounts are much greater than have been found by other ob- 

 servers, and his conclusions as to distribution of the ammonia are not 

 generally accepted. Levy at Montsouris ' 2 found as a mean 1'68 and 

 2'06 milligrams per 100 cubic metres in summer. The maximum ob- 

 served was 9 milligrams per 100 cubic metres, while on several occa- 

 sions no ammonia was present. According to Heinrich 3 air contains 

 the greatest amount of ammonia in June, the least in February. He 

 found three times as much in the summer months as in the winter, 

 while spring and autumn gave intermediate values. 



Ammonia,, in common with nitric acid and suspended matter, is 

 found in rain-water. 



According to Levy, rain (unlike air) in summer contains least and in 

 winter most ammonia. This may be due to the solubility of ammonia 

 being greater in cold than in hot water. At Montsouris 4 the following 

 were the mean amounts of ammonia per litre, rainfall (in mm.), and 

 quantity of nitrogen (ammoniacal) falling upon each square metre in 

 each of the following years : 



This, being practically town rain, is richer in ammonia than rain 

 falling in country places. As the average of 16 years' observations 

 Levy gives 2-2 parts of ammonia per million = 1 '82 parts of nitrogen 

 per million in the rain at Montsouris. (See also analysis of rain- 

 water, p. 25.) 



Bunsen observed that at the commencement of a shower the rain 

 contained 3*7 milligrams of ammonia per litre, while at the end only 

 0*64 milligrams were present. The author has also observed in the 

 Transvaal, that the content of combined nitrogen in the rain is often 

 roughly inversely proportioned to the amount of rainfall. 



Thus, in 1904 : 



1 Jour. Chem. Soc., 1874, Abstracts, 223. 

 *Ibid., 1877, 509; 1878, 243, and 1880, 848. 

 s lbid., 1898, Abstracts, ii. 3, 114. 

 4 Compt. Rend., 91, 94. 



