28 
Sm J. B. LAWES AND PROEESSOE J. H. GILBERT ON THE 
sufficient, yet, the data at command do not indicate tfiat these conditions could be 
adequately available in such cases as those of the very large accumulations of nitrogen 
by the red clover on the bean-exhausted land, and of the increasing and very large 
accumulations by the Medicago sativa for a number of years in succession. 
Accordingly, on September 3, 1885, when the holes were open for the soil sampling 
on the Medicago sativa plot, a specimen of the deep, strong, fleshy root of the plant 
Avas taken, and on examination it was found that the root-sap was very strongly acid. 
The roots of three plants were then collected. Of these, No. 1 bad four branches, 
Avhich were respectively—6 feet 4^ inches, 5 feet 10| inches, 3 feet 6-^ inches, and 
2 feet 9^ inches in length ; No. 2 had two branches—4 feet 10 inches and 2 feet 
2 inches in length ; and No. 3 had two branches, respectively 3 feet 9 inches and 
1 foot 9 inches in length. 
The roots were rapidly washed in distilled water, dabbed with clean cloths, weighed, 
rapidly cut into small pieces, and bruised into a pulp in Wedgwood mortars, with a 
measured quantity of ammonia-free distilled water. The pulp was then put upon a 
vacuum filter, and the resulting extract was made up to a given volume with pure 
distilled water. It was, however, found impossible to get the extract perfectly clear 
witliin the limited time it could be exposed to treatment without risk of change, and 
hence, in these initiative experiments, it was dealt with whilst still somewhat tm’bid. 
The dry matter, ash, and nitrogen were determined in the original root, in the root 
extract, and in the exhausted root. 
The important question was whether the acid root juice would take up nitrogen 
from a raw clay subsoil such as that from which the Melilotiis leucantha, the Medicago 
sativa, and the red clover, were supposed to have derived such large quantities in some 
way. Accordingly, 20 grams of subsoil from the unmanured wheat-fallow plot imme¬ 
diately adjoining the Melilotus and Medicago sativa plots, were added to a known 
quantity of the acid root extract in a stoppered bottle, well shaken, and the soil and 
liquid were left in contact for some weeks, the autumn holidaj's iirtervening. It was 
found, however, on examination, that the extract had lost, and the soil had gained 
nitrogen, nitrogenous organic matter having been deposited. 
In November, 1885, one of the Medicago sativa holes was reopened, and fresh 
quantities of root were collected. These were prepared in substantially the same wmy 
as before, but with much greater expedition, more persons being employed. The 
roots were rapidly passed successively through 4 basins of distilled watei’, which was 
renewed as needed."^ They were then dabbed with clean dry cloths as before, 
weighed, cut first into short lengths, and then into very small pieces, the whole being- 
kept in basins covered with glass plates as much as possible to lessen evaporation. 
The weight was then again taken, a known quantity of pure distilled water added, 
the Avhoie bruised in Wedgwood mortars, and re-weighed. 
* In subsequent experiments it bas been found that the wasb-water did not become acid during the 
process. 
