16 
On the Rain and Drainage - Waters at Rothamsted. 
proportion in the drainage-waters, each succeeding discharge 
being weaker than the one preceding ; this, however, is not the 
case. The soluble salts are indeed gradually removed in the 
drainage-waters, but weak discharges are followed by strong, 
and strong by weak, the composition of the water depending on 
the amount of the rainfall which occasions the outflow, and on 
the stage of the running at which the sample is taken. 
There is usually a distinction visible to the eye between an 
outflow containing much direct channel water, and one consisting 
wholly of the true discharge from the soil ; the former is usually 
more or less turbid, the latter always clear. The direct channel- 
water is, in fact, always turbid, save after hard frost, or shortly 
after the application of the artificial manures. We owe to 
VV. Skey, and to Th. Schloesing, the observation that the 
presence of various salts, especially salts of calcium, determines 
the coagulation of the particles of clay. In Broadbalk Field 
the drain age- waters from the plots receiving ammonium-salts are 
especially bright for some little time after these salts have been 
applied ; nitrate of sodium does not produce the same result. The 
reason of this fact is that ammonium-salts greatly increase the 
amount of lime in the drainage-waters, the sulphate or chloride of 
ammonium reacting upon the chalk of the soil, sulphate and 
chloride of calcium being produced, while nitrate of sodium 
produces no such effect. 
An excellent illustration of the difference in composition of 
turbid and clear waters is afforded by Frankland's analyses of 
January 19, and February 26, 1873. On January 19 there was 
a small flow of the drains ; all the waters were clear. The next 
running took place on February 26. There was again a small 
flow, resulting from the thaw of snow ; all the waters were turbid. 
The mean composition of the dissolved matter in the drainage- 
water from Plots 7, 8, 10, 11, 12, 13, and 14 on these two dates 
will be found in Table XLII. 
Table XLII. — Composition of Clear and Titrbip Drainage-Waters 
from Broadbalk Field, in parts per Million. (Dr. Frankland.) 
ToUl 
Solid 
Matter. 
Carbon 
Nitrogen as 
Date of Collection. 
in 
Organic 
Matter. 
Organic 
Matter. 
Am- 
monia. 
Nitrates 
and 
Nitrites. 
Total 
Nitrogen. 
Chlorine. 
1873. 
Jan. 19 (clear) 
543-9 
1-21 
0-39 
•03 
15-2 
15-6 
27-6 
Feb. 26 (turbid) .. 
311-3 
2-96 
0-78 
-07 
6-1 
6-9 
13-7 
