32 THE ATMOSPHERE. II. 



mainly due to the dried-up particles of sea-water cast into the 

 air as spray. The amount is always greatest near the sea and 

 smallest far inland ; it is greatly influenced by the direction 

 and force of the wind. Sulphuric acid is also partly attri- 

 butable to the same cause, but if its ratio to the chlorine be 

 more than 12 : 100 (the ratio in sea-water) combustion of coal 

 or the decay of animal or vegetable matter is probably to be 

 assigned as one of its sources. 



Another extensive series of analyses of rain-water collected 

 at Rothamsted was made by Frankland and published in 1881 

 and 1882* by Lawes, Gilbert, and Warington. From 69 sam- 

 ples collected in 1869-70 the following numbers were ob- 

 tained. (Parts per million) : 



Nitrogen. 



As As nitric As org. Total solids. Chlorine. Hardness, 



ammonia. acid. matter. 



Mean ... -37 -14 -19 33-1 3-1 4-7 



Maximum 1-28 -44 -66 85-8 16-5 16-0 



Minimum -04 -01 -03 6-2 -13 O'O 



In 1888-89 a series of monthly determinations of the 

 amounts of ammonia and nitric acid in the rainfall at Rotham- 

 sted was made by Warington. | The results are given in the 

 accompanying table : 



