2G8 On the Rain and Drainage - Watns at Rotliamsted. 
in some of the case recorded in the Table, and the compara- 
tively large quantities in others, seem difficult to explain, or 
to reconcile with one another. Nor do the results become 
more intelligible when considered in relation to those discussed 
in the foregoing pages, and to the comparatively limited and 
Table XVIII. — Determinations of the Quantity of Nitrogen sup- 
plied by Eain, as Ammonia and Nitric Acid, to an Acre of 
Land, during One Year. 
ivuiiiiaii. 
Nitrogen per Million, as 
Total 
^ itrogen 
per Acre. 
Ammonia. 
Nitric Acid. 
Inchea. 
lbs. 
Kuschen, 1864-5 
11-85 
0-54 
0-16 
1-86 
1805-G 
17-70 
0-44 
0-16 
2-50 
27-55 
0-55 
0-76 
0-30 
0-49 
5-49 
^i • G 1 
b ol 
Dahme, 1865 
17-09 
1-42 
0-30 
6-66 
Eegeuwalde, 1864-5 
23»48 
2-03 
0-80 
15-09 
1865-6 
19-31 
1-88 
0-4S 
10-38 
1866-7 
25-37 
2-28 
0-56 
16-44 
*Icla-Marienhutte ; mean of 6'l 
years, 1865-70 / 
Proskau, 1864-5 
22-65 
17-81 
3-21 
1-73 
9-92 
20-91 
Florence, 1870 
36-55 
1-17 
0-44 
13-36 
„ 1871 
42-48 
0-81 
0-22 
9-89 
„ 1872 
50-82 
0-82 
0-26 
12-51 
VaUombrosa, 1872 
79-83 
0-42 
0-15 
10-38 
Montsouris, Paris, 1877-8 .. 
23-62 
1-91 
0-24 
11-54 
„ 1878-9.. .. 
25-79 
1-20 
0-70 
11-16 
„ 1879-80 .. 
15-70 
1-36 
1-60 
10-52 
Mean of 22 years .. 
27-03 
10-23 
uniform amounts recorded for Montsouris, within the walls of 
Paris. As to the higher amounts, it is true that Liebig, in his 
earlier writings, assumed the probability of a very much larger 
quantity of ammonia coming down in rain than any indicated 
in the above Table, or than he did subsequently ; and even in 
his more recent work, 'The Natural Laws of Husbandry,' pub- 
lished in 1863, he supposes that as much as 24 lbs. of nitrogen 
per acre may be annually available to vegetation from that source. 
It will be observed, however, that neither do the early results for 
the open country obtained by Boussingault, nor do those ob- 
tained at Rothamsted, indicate more than about one-third of this 
amount ; and the more recent determinations in the Rothamsted 
rain-waters point to less rather than more than the earlier ones. 
* Details of these results are not at baud. Tbe rainfall given is really tbe 
average of seven years, 1864-70. 
