vi INTRODUCTION, 



As tills mode of determining the nutritive powers of grasses, by chemical process, is a new 

 path of investigation opened, and such as, on a subject of this consequence, should always be 

 proceeded in with caution at first, it may not be unnecessary to say a few words respecting the 



accuracy of its results. 



The grass, in a green or dry state, is submitted to the action of hot water, till all its soluble 

 parts are taken up. The hquor is then separated from the woody fibre of the grass by means of 

 blotting-paper ; it is then evaporated to dryness. The product or solid matter, is the nutritive 



4 * 



matter of the grass. Sir Humphry Davy has shown, that the soluble products, or nutritive mat- 

 ter of grasses consist, for the most part, of five distinct vegetable substances, viz. mucilaginous, 

 saccharine, albuminous, bitter extractive, and saline matters ; and that '' it is probable that the 

 excellence of the different articles, as food, will be found in a great measure proportional to the 

 quantities of soluble, or nutritive matters they afford ; but still these quantities cannot be re- 



h 



garded as ahsolutely denoting their value : albuminous, or glutinous matters, have the charac- 

 ters of animal substances ; sugar is more nourishing, and extractive less nourishing, than any 

 other principles composed of carbon, hydrogen, and oxygene ; certain combinations of these 

 substances, likewise, may be more nourishing than others*." 



A certain quantity of food will keep an animal for a great length of time, without increasing 

 pr diminishing its weight in any sensible degree ; but if the quantity of food be sufl&ciently 

 augmented under favourable circumstances, the animal becomes fat, and its weight consequently 

 increased. We have no means, however, to ascertain the exact proportions of food required for 

 these two purposes distinctly ; for it depends not on the quantity and quality of the food alone; 

 the age of the animal, and its exposure to heat or cold, are also concerned in the process. It 

 is likewise evident, that of two animals of the same breed or variety, the one will frequently 

 acquire a much greater weight of flesh in any given length of time than the other, though both 

 shall have been fed on the same kind of food, and in all other respects treated equally. The 

 nutritive powers of the food cannot therefore be determined absolutely, even by these means, 

 though the comparative merits and value of the different breeds or varieties of animals are 

 thereby fully ascertained; for it is manifest, that it is not the deficiency of nutritive matter ia 

 the food, but want of power in the animal to profit by it. 



The results of the numerous valuable experiments made by order of the late illustrious Duke 

 of Bedford, to prove the relative value of the different breeds of sheep and oxen, place the 

 truth of the above remarks in a clear light. I may be permitted, therefore, to quote from Mr 

 Young s - Annals of Agriculture,'' the results of one of these experiments, which was made on' 

 six oxen. 



* i( 



Agricultural Chemistry. 



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