450 PHYSIOLOGY AT THE FARM. 



of the grasses. It affords an early herbage, of which cattle, 

 especially cows, are fond ; but being an annual, and often de- 

 stroyed by a continuance of dry weather, it is rarely used in 

 cultivation. Nevertheless, as it sheds its seed twice or thrice 

 a-year, it is a valuable grass for giving a close and early 

 herbage in permanent pasture. 



Chemical Composition of the chief of the Forage Grasses. 

 Some progress has been made towards the chemical composi- 

 tion of a few of the forage grasses. The principal point in 

 which the analysis is still defective relates to the separate 

 materials of which the ash of each is made up. The investi- 

 gation of this part of their composition must be completed 

 before the analysis can be described as satisfactory. In the 

 mean time, as much is here stated as has been determined on 

 good evidence. 



Mr Sinclair was the first to attempt a chemical examination 

 of the forage grasses. His method, very imperfect as it is, was 

 a considerable step in advance. The plan was suggested to 

 him by no less an authority than Sir Humphry Davy. A 

 given weight of the grass to be examined was subjected to hot 

 water till all the soluble parts were taken up. The liquid was 

 then separated from the undissolved woody matter by filtra- 

 tion, and carefully evaporated to dryness. The dry product 

 thus obtained was concluded to be the measure of the nutri- 

 tive matter of the plant under examination. 



By a more exact scrutiny, such as the chemistry of the present 

 day permits, the following points are sought to be determined : 



1st, The proportion of water in each grass as taken from the 

 field. 



2d, The proportion of albuminous or flesh-forming principles 

 that is, of all the nitrogenous principles present. 



3d, The proportion of oily or fatty matters, such as are re- 

 garded as fat-producing principles. 



