428 Report of Expei'iments loith different Manures 
A lew brief remarks should first be made, as to the character 
of the several substances represented in the above enumeration. 
Nitrogenous substance. — The most practicable and usual mode 
of getting at an approximate estimate of the total amount of 
Nitrogenous compounds, in vegetable or animal food-stuffs, is to 
determine the amount oi nitrogen, and calculate from it the 
amount of Nitrogenous substances, on the assumption that they 
consist of tlie so-called proteine compounds. Adopting this 
assumption, the amount of Nitrogen has only to. be multiplied by 
(5'3, to give, very nearly, the amount of Nitrogenous proximates 
that it would represent. This is the method which, from con- 
venience, we have adopted. From what has been said under the 
liead of Nitrogen, however, it will be obvious, that this mode of 
estimation affords, more particularly in the case of succulent and 
unripened produce, at best but an uncertain indication of the 
amount of elaborated and nutritive Nitrogenous compound. The 
so-calculated Nitrogenous substance may, in fact, not only include 
a quantity of matter in a low condition of elaboration, but even 
aminoniacal salts. It will be understood, therefore, with what 
degree of reservation the recorded amounts of " nitrogenous 
substance " must be taken, as indicating the probable amounts 
of nutritive proteine compounds. 
Fatty matter. — Tlie substance given under the head of Fatty 
matter, includes, as has been already explained, a quantity of 
waxy and green colouring matter, and must not be taken there- 
fore as representing pure fatty matter of high respiratory and fat- 
forming capacity. 
Woady-fibre. — -It will be borne in mind, that the substance 
recorded as Woody-fibre, is not supposed to include the whole of 
the Cellular matter in its various modifications ; but only that 
amount of it which seems to possess a certain fixed degree of 
persistence, on tlie application of such solvents as are required to 
remove the other compounds. It is possible, however, that at any 
rate the easily changeable, and easily dissolved portions of the 
Cellular substance, mav be amenable to the digestive organs of 
animals. 
Other non-nitrogenous matters. — The substances put down as 
other non-nitrogenous matters, are all those which remain after 
deducting the " Nitrogenous substance," tlie " Fatty matter," and 
the "Woody-fibre," as above defined, and also the "Mineral 
matter." Tliey comprise probably starch, dextrine, gum, sugar, 
and certain extractive matters. They will also include so much 
of the more easily cliangcabh? Cellulose, or Cellular matter, as 
may have been dissolved hy the re-agents required to remove all 
the other matters, in the process adopted for separating and 
estimating the so-called " Woody-fibre." The characters, and 
