135 
It is evident that there is no appreciable difference between the 
warm and cold seasons. A slight addition is to be nade to the 
above table, in order to include the quantities of nitrogen contained 
in the water of fogs and dew. The quantities under the column 
“ Nitric acid ” includes such nitrites as become converted into nitrates 
in the laboratory analysis. The great variations in the successive 
seasons depend upon the variations in rainfall quite as much as upon 
the variations in the quantity of nitrogen per liter, or the variations 
in the atmospheric constituents. 
The variations in the quantity of nitrogen brought to the soil by 
the rainfall in different parts of the world is shown in the following 
table, as quoted by Marié-Davy from the memoir of Messrs. Lawes, 
Gilbert, and Warington, on the composition of the rainfall at Roth- 
amsted. This table shows that the richness of the rain in nitrogenous 
compounds varies geographically quite as much as the quantity of 
rain does, so that in general the ground in Germany, Italy, and 
France receives decidedly more nitrogen per acre than does the 
ground in England. A further study of the subject also shows that 
the rain caught in cities contains vastly more nitrogen, especially 
ammonia, than that caught in the open country. 
Quantity of nitrogen annually brought to the soil by rain. 
Total nitro- || | Total nitro- 
gen— E gen— 
Station. Date. | por | __ | Station. Date. | Bee eae 
hec- | Pei | hee- Per 
tare. |eoe tc | jer, || ASE 
Kilos. | Lbs. || | | Kilos. | Lbs. 
Keuschentreess. aac 2s) 1864-65 2.08} 1.86 || Proskau_........-..----| 1864-65 | 23.42 20.91 
CN aera 1865-66 | 2.80] 2.50 || Florence ..........--.-- | 1870 | 14.96| 13.86 
imsterburg. 22-2. -2-2- = -- 1864-65 | 6.15) 5.49 Wines Sek aes oe ee 1871 11.08 9.89 
IDO) 3k ee ee | 1865-66 | 7.63 6.81 | DOP ee ee ee eee | 1872 14.01 12.51 
Wahmert= ecw se 2s 1865 7.46) 6.66 || Vallombrosa -.--.-.--- | 1872 11.63 10. 38 
Regenwalde-..._...___- | 1864-65 | 16.90 | 15.09 | Rothamsted -------___. | 1853-54 6. 24 5. 96 
1D ESA eee | 1865-66 | 11.63 10.38 | DOPsen sn ae eee 1855 7.29 6.58 
ioe Skee eee ae (ISBBB7 +) Teran| “IGl4de||, Doss Lt. eee | 1856 8.85 8.00 
Ida-Marienhutte______- | 1865-70 | 11.12 9.92 |, Montsouris']-=2- 2-4. = | 1876-88 | 14.04 | 12.53 
The appreciable quantities of nitrogen shown in the above table 
must be diminished in agricultural computations in proportion as 
the rainfall carries it off into the rivers, since only that which remains 
in the soil can be supposed to have an appreciable influence on the 
growth of crops. 
The quantity of nitrates in rain water may be expected to vary 
with the character of the climate and may be greatest in those regions 
where lightning is most frequent. Observations on this subject were 
made by A. Muntz and V. Marcano (Agr. Sci., Vol. III, p. 278), who 
showed that at Caracas, Venezuela, where thunder storms are fre- 
