On the Rain and Drainage - Waters at Rothamsted. 259 
mination immediately after the collection of the water. The 
determination of ammonia in a year's rainfall would on this 
plan require a large amount of analytical work, for which at 
present sufficient time has not been found at Rothamsted. 
The proportion of nitrogen as nitrates and nitrites found l)y 
Professor Way and Dr. Frankland is seen to agree very nearly. 
Way lound on an average 0'12 per million of rain, while Frank- 
land's 34 analyses give a mean of 0"14. 
The determinations of organic carbon and nitrogen are full of 
interest ; they are, indeed, the only determinations of the kind as 
yet made in rain-water. The carbon and nitrogen represent 
the soluble matter extracted by the rain from the organic dust 
with which it has come in contact in the atmosphere, or on the 
surface of the collecting vessel. The average proportion of 
nitrogen to carbon when the gauge was washed before collection 
is 1 : 4-0 ; when the gauge was not washed, 1 : 5'2 ; the mean of 
all the samples is 1 : 4-8. The organic matter dissolved in rain 
is thus of a decidedly nitrogenous character. 
The chlorine found in rain-water is due to the presence of 
common salt. The average amount of chlorine shown by 
Dr. Frankland's analyses is 3"1 parts per million. 
The total solid matter dissolved in rain-water is considerably 
greater than the sum of the constituents mentioned in the Table ; 
the remaining matter will consist partly of sulphates, which 
Dr. Angus Smith has shown form a large ingredient of rain- 
water. 
We turn now to the analyses of dew and hoar-frost. The 
samples examined were seven in number. In the case of some 
of the samples the collection extended over several days, and 
embraced many distinct deposits. 
Table XII. — The Maximum, Minimum, and Mean Amounts of certain 
Constituents in Seven Samples of Dew and Hoar-Frost, in parts 
per Million. 
Total 
Solid 
Matter. 
Carbon 
Nitrogen as 
in 
Organic 
Matter. 
Organic 
Matter. 
Am- 
monia. 
Nitrates 
and 
Nitrites. 
Total 
Nitrogen. 
Chlorine. 
Hardness. 
Highest proportion 
80-0 
4-50 
1-96 
2-31 
0-50 
4r)5 
8-0 
25-0 
Lowest proportion . . 
26-4 
1-95 
0-26 
1-07 
0-28 
1-C6 
3-5 
13-0 
Mean, 7 samples .. 
48-7 
2-64 
0-76 
1-63 
0-40* 
2-79 
5-3 
190 
* Mean of 4 analyses. 
s 2 
