48 
SIR J. B. LAWES AND PROFESSOR J. H. GILBERT ON THE 
As to the ,results obtained with soils, with and without vegetation, it must be 
admitted that M. Berthelot has carefully considered, and endeavoured to estimate, 
all other apparent sources than free nitrogen. At the same time, the conditions of 
risk and exposure to accidental sources of gain in the experiments in the chamber, in 
the meadow, and on the tower, are such that the results could not of themselves be 
accepted as at all conclusive. To the distinct gains observed in the experiments in 
closed vessels no such objection can however be raised ; whilst the negative results in 
the sterilised soils constitute another element in favour of the conclusion at which 
M. Berthelot has arrived. 
It is, however, one thing to accept experimental results on the authority of 
M, Berthelot, and another to adopt his arguments and conclusions in the application 
of them to the conditions of practical agriculture. To avoid repetition, however, 
further reference to this part of the subject must be postponed until the results and 
conclusions of other experimenters have been considered; for, to a great extent, the 
same facts and arguments are applicable in reference to them, as to M. Berthelot’s 
results and conclusions. 
2. The ExjperimenU of M. P. P. Deherain.'"' 
The plan and methods of M. Deherain’s experiments to determine the losses or 
gains of combined nitrogen were totally different from those adopted by M. Berthelot. 
They were indeed much on the lines of some of the Rothamsted investigations. He 
sought to determine the actual losses or gains in the field, under the influence of 
different manures, of different crops, and of different modes of cultivation. His 
experiments were made on the farm of the Agricultural School, at Grignon, near 
Paris, and extended from 1875 to 1885 inclusive. The land had been in lucerne for 
5 years, 1870-1874. Four plots were then devoted to each experimental crop as 
under :— 
No. 1 received farm-yard manure. No. 2 nitrate of soda. No. 3 ammonium sulphate, 
and No. 4 was left unmanured. Each of the manures was applied 3 years in succes¬ 
sion, and then the crops were grown for four years more without further manuring. 
On one of the sets of four differently manured plots, green maize was grown. On 
a second set potatoes were grown dvu’ing the 3 years of manuring, and for two years 
afterwards, and then wheat for the two remaining years. On the third set beet was 
grown for 3 years, green maize for 1 year, and then sainfoin for 5 years, and mixed 
grasses for 2 years, to 1885 inclusive. 
The nitrogen was determined in the soil, before the commencement of the experi¬ 
ments in 1875, in 1878 after the three years of manuring and cropping, in 1881 after 
4 years crop23ing without further manuring, and in case of the sainfoin followed by 
mixed grasses, in 1885 also. Lastly the nitrogen was estimated in the crops. From 
* ‘ Aunales Agronomiques,’ vol. 8, p. 321, vol. 12, p. 17, and vol. 12, p. 97. 
