CHEMICAL COMPOSITION OF RAIN IN THE UNION 

 OF SOUTH AFRICA. 



By Charles Frederick Juritz, M.A.. D.Sc, F.I.C. 



In a paper by N. H. J. ^liller. Ph.D., on " The amounts of 

 nitrogen as ammonia and as nitric acid, and of chlorine in the 

 rain water collected at Rothamsted," published in the Journal of 

 Agricultural Science, Vol. I, October, 1905, pp. 280-303, Dr. 

 Miller compared the nitrogen and chlorine contents of Rotham- 

 sted rain with the amounts found in rain water from various 

 other parts of the world, as shown by analyses performed during 

 the previous forty years. Contrasting, as far as that could be 

 done, the composition of rain in tropical and in temperate coun- 

 tries, he came to the conclusion that tropical rain does not supply 

 the soil with an essentially larger amoimt of nitrogen than the 

 rain of temperate climates. Omitting some abnormal results at 

 Caracas and in Mauritius, he found that the average total nitro- 

 gen brought down to the soil by rain amounted to 3.58 lb. per 

 acre per annum in tropical countries, with the high average rain- 

 fall of 68.3 inches per annum. 



Dr. Miller tabulated the monthly results of analyses of the 

 rain which fell at Rothamsted during the period 1888 to 1901, 

 and stated the average amount of nitrogen at 3.84 lb. per acre 

 per annum, with an average rainfall of 27.25 inches per annum. 

 In winter the total nitrogen was found to average 1.80 lb. per 

 acre, and in summer 2.04 lb., the nitric nitrogen remaining con- 

 stant, so that the increase was entirely due to a larger production 

 of ammonia in summer. For every 1 part of nitric nitrogen he 

 found in summer rain 2.55 parts and in winter rain 2.15 parts of 

 ammonical nitrogen. 



Professor C. G. Hopkins, in his " Soil fertility and per- 

 manent agriculture," 1910, pp. 309. 310, records the proportions 

 of nitrogen brought to the earth annually by rain and snow in 

 various places. From his statements the following table has 

 been compiled : — 



Nitrogen. 

 Pounds per acre. 



Rothamsted 3.97 



Barbados 3.45 



Britisli Guiana 3.54 



Kansas 3.69 



Utah 5.42 



Mississippi 3.64 



Paris 8.93 



GembloUx (Belgium) 9.20 



Ottawa 4-32 



Several of the above figures, together with others not quoted 

 by Hopkins, are tabulated on page 286 of Dr. Miller's paper, 

 appended to which there is also a bibliography of titles of 125 

 publications relating to rain water and its chemical composition. 



It had been proposed to have a general discussion of the 



