100 Report of Experiments on the % Growt/r of Wheat. 
and elucidation, the discussion of such a vast amount of meteoro- 
logical record, and is, moreover, one of such intricacy, that it 
would be impossible to treat it at all satisfactorily within the 
limits that might otherwise have been devoted to so interesting 
and important a branch of the subject in the present paper. The 
consideration of the influence of season will, therefore, on the 
present occasion, be limited to pointing out, as matters of fact, 
the most prominent characteristics of the respective seasons, and 
the very great difference in the amounts and in the characters of 
the produce obtained under otherwise comparable conditions of 
growth, but in different seasons. 
Incidentally, however, the results brought out under this head 
will enable us to form some judgment as to whether the earlier 
or the later seasons of the experiments were, upon the whole, 
the less or the more favourable ; and, therefore, whether an 
increased or diminished result from the use of the same manure 
through successive years, is to be attributed mainly to the cumu- 
lative or the defective character of the manure itself, or, in any 
material degree, to a progressive or retrogressive character of the 
seasons. 
General Description of the Manures employed. 
Having regard to the constituents of the ash of wheat-grain, 
and of wheat-straw, it was sought to supply potass, soda, lime, 
magnesia, phosphoric acid, sulphuric acid, chlorine, and silica, 
respectively, in the most available and convenient forms. Omit- 
ting from the enumeration the amounts of mineral constituents 
provided in farmyard manure, cut wheat-straw, rape-cake, &c, 
or in the ashes of farmyard manure or wheat-straw, the more 
direct supply of the above-mentioned substances was as under : — 
Potass — As pearl-ash, sulphate of potass, or silicate of 
potass. 
Soda — As soda-ash, or sulphate of soda. 
Lime — As sulphate, phosphate, and superphosphate. 
Magnesia — As inagnesian lime-stone, or sulphate of mag- 
nesia. 
Phosphoric Acid — As bone-ash ; generally acted upon by 
sulphuric acid in quantity sufficient to convert a con- 
siderable portion of the insoluble earthy phosphate of 
lime into sulphate and soluble superphosphate of lime. 
Sulphuric Acid — As sulphate of potass, soda, or magnesia, 
in the phosphatic mixture last mentioned, &c. 
Chlorine — As hydrochloric acid (with bone-ash), or as 
chloride of sodium (common salt), &c. 
Silica — As artificial silicate of potass ; formed by fusing 
together equal parts of sand and pearl-ash. 
