66 THE ROYAL SOCIETY OF CANADA 



No account has been taken by previous investigators of the 

 nitrogen which is determined as albuminoid ammonia. The reason 

 for this omission is somewhat difficult to conceive as this nitrogenous 

 compound is undoubtedly valuable for plant growth. There is 

 no doubt but that the action of the wind on the soil, creating dust, 

 must affect the albuminoid ammonia content very markedly, and 

 it is significant that those samples of rain collected during or sub- 

 sequent to high winds contain a large amount of deposit and are in- 

 variably high in albuminoid ammonia. Generally speaking, the snow 

 is richer in suspended matter than rain, and it will be seen that the 

 proportion of the total nitrogen in the former reported as albuminoid 

 ammonia (20%) is higher than the proportion in the latter (14%). 

 Owing to the nature of the snowfall, it would be expected that it 

 would carry down more dust particles than the rain. 



The high winds which occur at times during the hot months, 

 may become almost cyclonic. These, frequently accompanied by 

 thunder storms, have a very disturbing effect on the nitrogen content 

 of the rain. If the surface soil is dry, as after a period of drought, 

 the air during these wind storms becomes charged with particles of 

 organic matter, manure, etc., which naturally have a pronounced 

 influence in increasing the nitrogen content of the ensuing precipita- 

 tion. While the direction of the wind, whether to or from the city 

 (in the absence of sulphite fumes contamination), does not appear 

 to have an appreciable effect on the rain, the velocity and character 

 of the wind, as already pointed out, certainly influence the quality 

 of the rain as regards its nitrogen content. Electrical discharges, 

 it might be supposed, would tend to induce a higher concentration of 

 nitrogen occurring in the form of nitrates, but in support of this 

 conclusion we have not been able to obtain any direct evidence. 



During the months of September, October and November of 

 the year 1908, the rain was particularly high in free ammonia. A 

 very severe drought existing during August and the earlier weeks 

 of September allowed the bush fires, which were prevalent at that 

 time in the districts surrounding Ottawa, to gain considerable head- 

 way, so that air was at times filled with smoke to such a degree as to 

 cause irritation of the eyes and mucous lining of the throat. The 

 scanty rains falling during or immediately subsequent to this period 

 were heavily impregnated with smoke and dust particles and the 

 high nitrogen content then recorded is attributed to this abnormal 

 condition of the atmosphere. 



When brief intervals only, say less than 48 hours, elapse between 

 showers and there is as it were a succession of rains, a noticeable falling 



