Nutritive Matter of Grasses. 



185 



quantity of water present in them — that is to say, that a "lass 

 containing 60 per cent, of water would furnish one-fourth k'ss 

 only of ammoniacal salts than one in whicli the water was 80 })cr 

 cent. 



With this modification^ then, the source of error now under 

 discussion would equally apply to all the samples, and would not 

 materially affect their relative nutritive value, which it has been 

 the chief object of this paper to establish. 



Those readers, however, who will take the trouble to examine 

 the subject will see that whilst the differences in albuminous 

 matter in the grasses are far too great to be due to such a cause, 

 it is not really the case (at all events as a rule) that the highest 

 percentage of moisture is accompanied by the largest proportion 

 of albuminous matter. 



Not denying, therefore, as I said before, the necessity of 

 bearing in mind the objection existing to the determination of 

 albuminous matter by that of the nitrogen (which, however, is 

 ^practically still likely to be the most correct, because by far the 

 most simple way of ascertaining the proportion of these matters), 

 I do not, for the reasons stated, attach much weight to it in the 

 present instance. 



3. The determination of fatty matters in the dry grass was 

 digested in hot ether, and repeatedly washed with the same 

 liquid. The ethereal solution was then distilled in a globular 

 flask in the water-bath, and the residual oil and fatty matters 

 weighed repeatedly till the weights remained constant. 



The numbers in Table IX. were obtained in the estimation of 

 the nitrogen and fatty matters of the grasses in each instance 

 where a second analysis was made. 



4. and 5. The starch, gum, sugar, &c., and the woody fibre, 

 were (^letermined in this way. 



A given weight of the grass was digested with heat in a 

 moderately strong solution of caustic potash ; the liquid was 

 decanted off, and a fresh solution of potash employed. The in- 

 soluble matter was thrown upon a filter and washed with boiling 

 water till the liquid coming through was pure water. It was 

 believed that in this way gum, sugar, starch, &c., together with 

 the albuminous matters, were dissolved, and the insoluble residue 

 was woody fire Avith a certain amount of ash. The insoluble 

 matter was carefully dried, and after being weighed was burned, 

 the residue being the mineral matter which was deducted. 



6. The ash was obtained in the usual way by burning the 

 grass. 



It is plain that we have in the above methods the data for 

 calculating the percentage of each of the classes of substances 

 enumerated above. 



