THE FOURTH liDITlON. 11 



value, therefore, in regard to produce, and the par- 

 ticular seasons at which it was in perfection, with 

 the kind of soil most favourable to their growth, 

 and the peculiar habits of the different species, were, 

 by these means, satisfactorily ascertained ; but the 

 comparative degree of their nutritive powers was 

 still to be determined. 



To compass this was the chief object: and to 

 arrive at something like certainty on this point, the 

 Duke resolved to obtain it by a simple chemical 

 process, as recommended by Sir H. Davy, and the 

 results were highly satisfactory. 



The process is simply this: — Equal quantities of 

 the different grasses, either in a green or dry state, 

 are submitted to the action of hot water, till all the 

 soluble parts are taken up. The liquor is then sepa- 

 rated from the woody fibre by means of blotting pa- 

 per : it is then evaporated to dryness. The product, 

 or solid matter, is the nutritive matter of the grass 

 or hay. Thus the comparative value of two kinds of 

 grass or two kinds of hay are found; or the pro- 

 perties of any given one. Sir H. Davy has shown 

 that the nutritive matter of grasses consists, for the 

 most part, of five distinct vegetable substances, viz. 

 mucilaginous, saccharine, albuminous, bitter extrac- 

 tive, 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 regarded as abso- 

 lutely denoting their value : albuminous or glutinous 

 matters have the characters of animal substances: 



