36 
SIR J. B. LAWES AND PROFESSOR J. H. GILBERT ON THE 
insoluble nitr 9 genous compounds in soils, and of the changes they undergo, when sub¬ 
mitted to the action of hydrochloric acid, of various strengths, for shorter or longer 
periods, and at different temperatures. The soil they employed contained 0'1744 per 
cent, of nitrogen. It was therefore much richer than our lucerne surface soil, and about 
four times as rich as our wheat-fallow subsoil. It was shaken in a flask with water, 
or dilute hydrochloric acid, in the proportion of 500 grams soil to 1000 c.c. liquid. 
The clear liquid was just neutralised by potash, then made slightly acid, calcined 
magnesia added, and the ammonia distilled off, collected, and determined. The 
remaining liquid was then acidified by sulphuric acid, evaporated to dryness, and 
the nitrogen determined by the soda-lime method, the result indicating the amount 
of soluble amide. The following is a summary of their results, which we give in parts 
of nitrogen per million soil, so as to compare with our own :— 
I. Pure water. 
o / 10 c.c. hyclrocliloric acid to 400 water 1 
- 1 (= HCI 3-5 gr.) ..f 
q / 50 C.C. hydrochloric acid to 400 Avater 1 
1 (= HCI 17-5 gr.) ./ 
. f 100 c.c. hydrochloric acid to 400 water I 
1 (=HC135gr.)./ 
Nitrogen per million soil. 
As ammonia. 
As soluble amide. 
18 
5 
2 
18 
5 
2 
hours, 
days, 
hours, 
hours. 
days. 
hours, 
cold. 
cold. 
at 100° C. 
cold. 
cold. 
at 100° C. 
17 
8-3 
4-8 
875 
48-8 
2775 
30-25 
123-6 
14-4 
21-4 
lOI-O 
60-6 
90-5 
356 9 
14-9 
30-4 
124-1 
68-6 
96-5 
430-3 
The authors call attention to the facts, which are clearly brought to view in the 
above arrangement of their results, that the amounts, both of ammonia, and of soluble 
amide obtained, increase with the strength of the acid, the time of contact, and the 
temperature. They point out that these are products of the action of the acid on 
certain insoluble nitrogenous bodies in the soil, and that the reaction is similar to that 
which they have observed in the case of urea, asparagin, and oxamid—that is with 
well defined amides. TTie insoluble nitrogenous compounds in the soil are in fact, as 
previously supposed, amide bodies. They also call attention to the fact that when the 
clear, filtered, acid extract is exactly neutralised by potash, one portion of the amide 
still remains soluble, whilst another is precipitated, showing that the amides rendered 
soluble constitute two groups. The fact of such re-precipitation is quite in accordance 
with the results obtained in our own ex|)eriments, in which less nitrogen remained 
dissolved after 24 than after only 1 hour’s contact, when, with the longer contact, tlie 
acidity of the extract became neutralised. 
A special point of interest in these results, as compared with those of Loges, is in 
