Beans and Peas, Sfc. 



481 



These three points of inquiry will, it is believed, successively 

 develope themselves as we proceed to detail the analyses. 



I should here state to what kind of analysis the inquiry has 

 been limited. Linseed, as before mentioned, contains albumi- 

 nous matter, oil, mucilage, and sugar, together with a certain 

 quantity of mineral matter, or " ash." 



The mucilage (or gum) and the sugar have no doubt their 

 share in the value of the cake as food. It is indeed contended 

 by some that sugar serves in the animal to the production of fat : 

 they are more usually, however, considered in the light of " ele- 

 ments of respiration " only, and not as employed either in the 

 formation of flesh or fat. And holding, as is generally done by 

 chemists of the present day, the doctrine of the simplest adoption, 

 so to speak, of the vegetable principles into the animal frame — 

 the more nearly allied to each other, the less being the effort on 

 the part of the system — it is hard to believe that, in the presence 

 of oil in abundance, nature should have recourse to sugar for the 

 production of fat. 



The quantity of oil, as representing the fat-forming principle, 

 and of albuminous matter, as indicating the feeding qualities, 

 seemed the points of principal importance in the chemical history 

 of linseed-cake. With these it appeared important to ascertain 

 the per-centage of ash, in order that any introduction, accidental 

 or intentional, of sand or other inorganic matter might be 

 detected. 



The quantity of albuminous matter in vegetable substances is 

 now usually estimated by the proportion of nitrogen which they 

 yield. The different modifications of albumen, gluten, casein, 

 <&c, are, with one exception, so nearly alike in composition (con- 

 taining about 15 75 per cent, of nitrogen) that it is more exact 

 to determine their proportion by that of the distinctive element 

 (nitrogen) than by recourse to methods for the separation of the 

 proximate principles themselves. It is not doubted that a full 

 analysis of linseed-cake, as well as of the other vegetable sub- 

 stances used in feeding cattle, would be a great boon to agricul- 

 ture; but in the existing state of knowledge as to the relative 

 offices of different constituents in the production of muscle and 

 fat, the present inquiry has appeared to offer advantages, as em- 

 bracing a far larger number of specimens than could be examined 

 in a more detailed form. 



The larger number of the analyses of linseed and oil-cake that 

 follow were made by Mr. Ogston in my laboratory ; some few, 

 however, having been executed by Mr. Ward and Mr. F. Eggar. 

 Of the nitrogen, a duplicate determination has in all cases been 

 made ; and, both to give confidence in the results and to impress 

 upon the present contribution that air of exactness which should 



