of simple alimentary Substances, tyc. S3 



peared to me, without complete success. About the same 

 time also albumen and other animal products, as urea, lithic 

 acid, &c. were examined with similar views. The subject of 

 digestion, however, had for a long time occupied my particular 

 attention ; and by degrees I had come to the conclusion, that 

 the principal alimentary matters employed by man, and the 

 more perfect animals, might be reduced to three great classes, 

 namely, the saccharine, the oily, and the albuminous : hence, 

 it was determined to investigate these in the first place, and 

 their exact composition being ascertained, to inquire after- 

 wards into the changes induced in them by the action of the 

 stomach and other organs during the subsequent processes of 

 assimilation. In conformity with this plan, the object of the 

 present communication is the consideration of the first class 

 or family above mentioned, namely, the saccharine. 



Preliminary observations on the analysis of organized substances. 



Vegetable substances contain at least two elements, hydro- 

 gen and carbon ; and most generally three, hydrogen, carbon, 

 and oxygen. Animal substances are still more complicated ; 

 and besides the above three, usually involve a fourth element, 

 namely, azote, to which they appear to owe many of their pe- 

 culiar properties. These general facts have been known ever 

 since the elements themselves have been recognized as distinct 

 principles, though the determination of the exact proportions 

 in which they enter into any particular substance, has always 

 proved a most difficult problem. To enumerate all that has 

 been done on this subject would be loss of time ; and it need 

 only be mentioned, that all idea of separating the different 

 elements from one another, so as to obtain them per se, has 

 been long since abandoned, if indeed it was ever entertained; 

 and the general principle on which the analysis of organic 

 products has been usually conducted, has been to obtain their 

 elements in the form of binary compounds, either by destruc- 

 tive distillation, as was formerly practised ; or by combining 

 the elements with some other element with which they pos- 

 sessed the property of forming definite binary compounds, 

 from the quantity and known composition of which, those of 

 the original elements might be readily obtained by calcula- 

 tion. For this latter purpose oxygen has been the principle 

 usually employed, which, as is well known, forms water with 

 hydrogen, and carbonic acid gas with carbon; two compounds 

 not only as well understood as any in chemistry, but likewise, 

 from their physical properties, well adapted for the purpose. 

 When azote is involved, other means must be adopted, which 

 will be fully considered hereafter. 



New Series.Yol 3. No. 13. Jan. 1828. F The 



