Oil the Rain and Draiiiarje -fFaters at Rotkamsted. 21) 
production and removal of nitrates. The so-called " Winter " 
season begins with the sowing of the manures towards the end 
of October, and continues till the sowing of spring manures 
earlj in March. The so-called " Spring " coincides with the 
early growth of the crop, and concludes with the end of May. 
" Summer " is here reckoned as the period in which the crop has 
full possession of the land, and lasts from the beginning of June 
to the commencement of harvest. "Autumn" is reckoned from 
harvest to the date of manure sowing in October. For each of 
these four periods the analysis of the first and last general 
running of the drains is given, whenever such occurred, with the 
mean of all the general runnings in the period. The progressive 
alterations in the composition of the water are thus plainly shown. 
In reading Table XLVI. we must remember that 100 lbs. of 
chloride of ammonium are applied to Plot G, 200 lbs. to Plot 7, 
and 300 lbs. to Plot 8 ; while Plots 10, 11, 12, 13, 14, 15, and 
one of the alternating Plots 17 and 18, receive annually 200 lbs. 
Plots 3&4 and 16 are unmanured, and receive only the 
chlorine contained in the rain (see Part I. of this paper). Plots 
5, 9, and 19 have no chlorine intentionally supplied in the 
manure, but the first two will receive a little, owing to the acci- 
dental impurities of commercial salts. The plot of the alter- 
nating series, 17 and 18, which receives the mineral manure, 
will have more or less of unwashed-out chlorides remaining in 
the soil from the application of ammonium-salts in the preceding 
year. Plot 19 will also contain some residue of its previous 
manuring with chlorides. 
During the whole of the three seasons (1878-9 to 1880-81) 
included in the present tables, the ammonium-salts have been 
applied to Plot 15 in the autumn, and to all other ammonia plots 
in the spring. Of the alternating plots (17 and 18), Plot 17 
received the ammonium-salts in the spring of 1878 and 1880 ; 
and Plot 18 in the spring of 1879 and 1881. The nitrate of 
sodium on Plot 9 has always been applied in the spring. 
A glance at the results in Table XLVI. will show that the 
drainage-waters are all extremely rich in chlorides immediately 
after the application of the ammonium-salts.* The amount of 
chlorine in the first runnings of the plots receiving 200 lbs. 
of chloride of ammonium has averaged 89*7 per million during 
the three years in question, has frequently exceeded 100, and in 
one case reached 160 per million. The amount of chlorine 
in the drainage-waters reaches its minimum at the end of the 
^ • The first running in November 1878, given for Plot 15 (Tables XLVI. and 
XLVII.) shows far less chlorine, and less nitric acid than would be generally 
present in the first running of this plot. The running on November 28 is in fact 
not the first running; a large running took place on November 10, of which, 
unfortunately, we have no analyses. 
