t while the
ammonia in sewage was converted into nitric acid, no change took place
in solutions of ammonia or urine prepared in the laboratory.

[105] Bisulphide of carbon and phenol (carbolic acid) have also been
experimented with in connection with their antiseptic action on
nitrification. In these experiments the former had a similar effect to
chloroform; the phenol, however, while hindering it did not entirely
suspend it, due probably to the difficulty of bringing the phenol vapour
into thorough contact with the soil-particles.

[106] Winogradsky has named the nitrous organism _nitrosomonas_, and the
nitric organism _nitrobaeter_.

[107] From a series of Lectures delivered by him in connection with
Lawes Agricultural Trust, in the United States.

[108] This silica-jelly consists of dialysed silicic acid, ammonium
sulphate, potassium phosphate, magnesium sulphate, calcium chloride, and
magnesium carbonate.

[109] This fact is all the more striking when we remember that this
decomposition of carbonic acid is best effected in the dark, since light
is prejudicial to nitrification.

[110] See Appendix, Note II., p. 196, and Note III., p. 197.

[111] See Appendix, Note V., p. 198.

[112] This is shown by the fact that nitrification will only continue in
a solution of carbonate of ammonia till one-half the ammonia is
nitrified. It then stops. The base, with which the nitrous acid combines
as it is formed, being at that stage entirely used up, nitrification is
no longer possible. With regard to urine solutions the same is the case.
Nitrification thus will only take place where there is a sufficiency of
base.

[113] See Appendix, Note IV., p. 197.

[114] It would seem that an alkalinity much exceeding four parts of
nitrogen per million is prejudicial to the process.

[115] According to Warington, solutions containing 50 per cent of urine
become nitrifiable when sufficient gypsum is added. The gypsum
neutralises the alkalinity of nitrifying solutions by converting the
alkaline ammonium carbonate into neutral ammonium sulphate, the calcium
carbonate being precipitated.

[116] See Chapter on Farmyard Manure.

[117] As practically illustrating this fact, a solution kept at 10 deg. C.
required ten days, while a solution kept at 30 deg. C. required only eight
days for nitrification.

[118] In sixty-nine trials no failure to produce nitrification by
seeding with soil from a depth, of 2 feet was experienced. Simila