206 Mr. Hall, Dr. Miller, and Mr. Gimingham. _[Dee. 19, 
70° to 80°, and the other placed in a thin layer under a bell jar over water. 
At the end of five weeks these second portions were similarly dried, and the 
two sets of samples, after removal of stones and reduction to a powder, were 
washed on a pressure filter with successive portions of water; the nitrates 
were determined in the extract by reduction and distillation of the 
ammonia. In the second trial the surface soil only, to a depth of 9 inches, 
was sampled in July, 1907; the exposure, made in the same way, was on this 
occasion continued for two months. 
The following table shows the amount of nitric nitrogen per million of dry 
soil both before and after exposure, also the differences between the two sets 
of figures to show the amount of nitrates formed during the exposure. 
Rothamsted Grass Soils. . October, 1906. 
Nitrogen as Nitric Acid per Million of Dry Soil. 
1st 2nd ord Ath 5th 6th 
9 inches. 9 inches. 9 inches. 9 inches. 9 inches. 9 inches. 
Plot. 
In Soil before Exposure. 
3 Unlimed 1°06 = 0°54 — 2°19 1°33 
4-2 Limed... 4°33 = 0°88 2°92 — 0°39 
4-2 Unlimed 3°75 1°39 1-07 1°13 1 ‘09 0 67 
9 Limed... 2°25 1°75 1°35 0°79 1:08 2 00 
9 Unlimed 2°38 ee: 0°90 1°20 0°47 0°58 
11-1 Limed... 2 °38 0-92 1 ‘09 0°79 0 ‘92 0°92 
11-1 Unlimed 3 ‘00 1 ‘20 1°39 1 08 1°83 1°83 
14 Unlimed 4°75 1 ‘33 2 ‘60 0°44 0°83 0°53 
In Soil after Exposure. 
3  Unlimed 1°41 0°97 0°67 1-08 0-96 0°63 
4-2 Limed... 6°12 2 04 1:00 2-00 3°66 0°36 
4-2 Unlimed 5°96 2°30 1°17 1°15 1 ‘04 0 “67 
9 Limed... 2°70 2°54 1 ‘30 1°32 1°25 1°49 
9 Unlmed 3 42 1°15 0°77 1°39 1°14 0°79 
11-1 Limed... 2 67 2°10 1°53 1°12 0°83 0°58 
11-1 Unlimed 2 ‘96 2 °08 1 ‘63 1 46 1 ‘92 0°92 - 
14 Unlmed 8°42 1 ‘50 2°50 1 ‘09 0-79 0°53 
Gain or Loss by Exposure. 
3 Unlimed +0°35 — +0°13 — —1°23 —0°‘70 
4-2 Limed... +1°79 == +0°'12 —0 ‘92 — —0°03 
4-2 Unlimed +221 +0°91 +0°10 +0 °02 —0°05 0 
9 Limed... +0°45 +0°79 —0°05 +053 +0°17 —O'al 
9 Unlimed +104 +0 ‘04 —0°13 +0°19 +0 67 + 0:24 
11-1 Limed... +0°29 +1°18 +0 °44 + 0°33 —0-09 —0°34 
11-1 Unlimed —0°‘04 +0 °88 + 0°24 +0°38 +0 ‘09 —0°91 
14 Unlimed +3 °67 +0°17 —0-°10 + 0°65 —0 °04 0) 
July, 1907. First 9 inches of depth only. 
Plot. At starting. After exposure. Gain by exposure. 
3 1°78 : 2°51 0°73 
4-2 3°39 9-01 5 62 
9 6°17 6°79 0 62 
11-1 12 °44, 13 °38 0°94 
14 10°77 13 ‘03 2°26 
