598 
On the Valuation of Unexhausted Manures. 
Although the figures given in the Table (I., p. 597) may be 
taken as fairly indicating the average composition of the 
different foods, yet it must be understood that in the case of 
almost every one of the articles in the list, individual samples 
may varv even considerably from the average. In the case of 
foods which are manufactured, or imported, the percentage of 
dry matter is usually high. In the case of those which may 
be either imported or home-grown, the variations in the per- 
centage of dry matter in different samples may be compara- 
tively wide ; it being, as a rule, distinctly higher in the 
imported articles, which could not be shipped unless in a drier 
condition than is usual with the home-grown product. In such 
cases, therefore, the imported food will probably contain a 
higher, or the home-grown one a lower, percentage of dry 
matter, than the average amount given in the Table. Even in 
the case of professedly ripened products, such as cereal grains 
and leguminous seeds, the character of the season will materially 
influence their condition of dryness ; and the same remark 
applies, in a greater or less degree, to such matters as hays and 
straws. Succulent matters again, such as roots, vary very 
considerably according to season, and to condition of maturity. 
So far as individual constituents are concerned, very similar 
reservations must be made ; and especially is this so in the case 
of the nitrogen. Even with professedly ripened products, the 
percentage of nitrogen may vary considerably according to soil, 
manuring, climate or season, &c., but especially according to 
season ; and this is the case in a less degree with the phosphoric 
acid, and the potash, of such articles. But in the case of im- 
perfectly ripened products, such as hay, and in a much greater 
degree in that of still less evenly matured and more succulent 
ones, such as roots, the percentage of nitrogen may vary very 
materially, and that of the phosphoric acid and potash to some 
extent. 
Whilst, therefore, the figures given in the Table may be 
taken as representing the fairly average composition of the 
different foods, they must be adopted or modified with judg- 
ment, having regard to the influence of the conditions of 
growth, maturity, preparation, or preservation, to which they 
have been subject. Fortunately, however, unless the variation 
from the standard composition adopted in the Table be con- 
siderable, indeed more than is usual, the effect on the estimates 
of manure-value will not be material; but they will obviously 
be much greater in the case of the nitrogen, than in that of 
either the phosphoric acid or the potash. 
