256 
Growth of Wheat. 
a very porous sandy loam resting on gravel which contrasts 
favourably with the clayey loam that overlies the chalk at 
Rotbamsted. In the words of M. Barral, " Le sol en est 
argilo siliceux, de consistance assez legere melange de gravier, 
avec un soussol forme d'un gravier assez compacte." This 
is evidently a poor soil, and therefore well suited for testing 
the relative action of different manures. In one respect, how- 
ever, it seems doubtful whether the French trial-field, situate 
on the skirt of the Wood of Vincennes, be a good repre- 
sentative of general husbandry ; for if it be new land — a recent 
clearing on which humus has more or less accumulated, the 
advocates of the mineral theory will hardly have pitched upon 
a fair field of battle. 
Preparatory to the experiments, the soil was stirred to the 
depth of from 8 to 10 inches bv the hand-grubber (la beche) a 
short-handled picker, with either a broad point or with bent 
prongs, — a most effective implement in the hand of the peasant 
proprietor for autumn or winter cultivation. 
M. Ville's design is to test manures of four different classes, 
nitrogenous, phosphatic, calcareous, and alkaline, in varied com- 
binations, and in contrast with the unmanured soil. 
To this end, directly after the grubbing, the trial wheat-plots 
(1 are = 4 poles nearly) received in December, 1860, the 
following dressings as here computed for the English acre : — 
lba. 
Muriate of ammonia 579 
Phosphate of lime 352 
Double silicate of potash and lime .. .. 528 
The muriate of ammonia was derived from the sal ammoniac 
of commerce, it contained 24 , !)2 per cent, of nitrogen ; this supply 
was reckoned to correspond with that furnished in 10 tons 18 cwts. 
of farmyard manure. The phosphate of lime was obtained from 
the precipitation of chloride of calcium by phosphate of soda ; it 
was consequently a very pure and fine substance. The double 
silicate of potash and lime was provided by M. Kuhlmann, of 
Lille, and it contained one-third part of potash, one-third of 
lime, and one-third of silica, or silicious acid. The cost was 
estimated at from 8/. to 91. 10s. per acre. 
This single dressing has afforded three successive crops (two 
of spring wheat, the last of winter wheat), amounting each 
year, as the ' Moniteur ' asserts, to 35 hectolitres per hectare 
(38 \ bushels per acre). 
The Abbe Moigno in his Journal, ' Les Mondes,' speaks of 
these crops as " the most astonishing verifications of the experi- 
ments of the laboratory," demonstrating the part which each 
constituent of a complete manure plays in the development of 
