530 Experiment on the Elementary Principles of 3Ianure 
2. Phosphorus ; 3. Alkalis and principally potash ; 4. That 
which constitutes the bulk of clung, the strawy matter, or, in 
chemical language, carbon. 
The nitrogenous matter employed was nitrate of soda, which 
has been proved to be tantamount to ammonia for agricultural 
purposes ; and I am obliged to employ this term nitrogenous 
matter because it is doubtful whether the ammonia be converted 
into nitric acid or the nitric acid into ammonia before they 
respectively enter the frame of the plant. Nitric acid, as I 
proved last year, acts directly upon vegetation, a result to which 
I felt justified in ascribing the novelty of a discovery ; because, 
even if it had been demonstrated, which it had not, that this 
acid was the active principle in nitrate of soda, it would by no 
means follow as a matter of course that the acid would be found 
operative alone. In simple chemistry it would be so, but not in 
organic chemistry, as is well known to medical practitioners, 
who would by no means expect such indifference of reception by 
the animal stomach. 
As the experiment relates to the fundamental principles of 
agricultural science, I may venture to describe it minutely. It 
was made by drilling separately superphosphate and peat- 
charcoal with wheat in the autumn, and top-dressing a portion 
of each lot in the spring with cubic saltpetre. The fourth 
element, potash, I thought better, from its solubility, to apply 
also in spring. 
The question of the efficacy of superphosphate on wheat 
seemed to me especially interesting, because of its vigorous 
efficacy when applied singly to the growth of turnips. 
The result of the trial is given in the following table : — ■ 
Ditto with a 
Bushels of topdressing of 
Wheat, 170 lbs. J^itrate, 
Per Acre. per Acre. per Acre. 
4 cwt. of superphosphate 7 19^ 
6 cwt. of peat charcoal Sf 18 
Nothing 7i I9J5 
It is evident th,at the superphosphate, though all-important for 
roots, has done nothing for the wheat, even on this poor and 
exhausted land. The charcoal would appear in the first column 
to have done something, l)ut as that result is not confirmed by 
the combined trial, the difference must, I think, be accidental. 
The fourth element, potash, was tried by top-dressing an acre 
of wheat with 1 cwt. of pearlash, which was so evidently in- 
operative on the crop as to render any separate thrashing un- 
necessary. 
As far then as we can rely on this experiment, carefully made 
with soil duly prepared by previous exhaustion, the only clement 
