E. J. Russell and E. H. Richards 



317 



Since the larger part of the rain comes from the Atlantic it would follow 

 that most of the ammonia would come from there also. 



This view was held by Boussingault and developed by Schloesing^ 

 in an important series of papers. It has been subjected to a critical 

 examination at Rothamsted. 



Arrangements were made for the systematic collection of samples 

 of rain at various stations (usually lighthouses) in the Hebrides and in 

 Iceland, remote from atmospheric pollution. These samples were then 

 sent to Rothamsted for analysis. 



The results were^ 



Much less ammonia was found than at inland stations and it was 

 not always certain that the sample collected was as pure as the rain. 

 In spite of serious efEorts there was considerable difficulty at the 

 lighthouses in keeping the rain gauges free from bird droppings, and 

 it is possible that some of the ammonia came from adventitious con- 

 tamination. 



No analyses, so far as we know, have been made of rainwater collected 

 on the Atlantic itself. One of us (E. .J. R.) made several attempts to 

 secure good samples when crossing and recrossing in 1909 and again in 

 1912, but without success. But even if the atmosphere over the Atlantic 

 is not entirely free from ammonia, it certainly contains considerably 

 less than that over the land. We therefore cannot agree with Schloesing 

 that the bulk of the ammonia comes from the sea, though possibly part 

 of it does. 



It seems necessary therefore to suppose that some, if not all, of the 

 ammonia is derived from the atmosphere. Owing to its high solubility 



1 Comp(. J?en<f., 1875. 80, 175. "Sur rammoniafiuedel'dtmosphere." /6«rf.,81,81 and 

 1252; 1876, 82, 747, 846 and 969. 



« N. H. J. Miller, JovLtn. Scottish Meitorol. Soc., 1913, iii, 16, 141. 



