APPENDIX. 



No. I. 

 OF THE MODE OF ANALYZING ORGANIC BODIES. 



THE constituents of the greater number of organic bodies are 

 carbon, hydrogen, azote, and oxygen. In animal bodies usually 

 all the four exist together ; but in many vegetable bodies, as 

 acids, alcohols, sugars, starch, and gum, only hydrogen, carbon, 

 and oxygen are to be found. Now to analyze an organic body 

 is to determine with accuracy the weight of the carbon, hydro- 

 gen, azote, and oxygen, respectively, of which it is composed. 



The method of performing this analysis was first contrived by 

 Gay-Lussac, and Thenard, in the year 181 1.* They first inti- 

 mately mixed the substance to be analyzed with about twice as 

 much dry and fused chlorate of potash as was necessary to burn 

 it completely. This mixture was made up into small round balls 

 about half the size of a pea. They were dried at the tempera- 

 ture of 212, and the exact quantity of chlorate of potash and of 

 the substance to be analyzed, contained in them was accurately 

 determined. These balls were dropped one after another into a 

 stout glass tube shut at its lower extremity, and having a stop- 

 cock cemented into its upper extremity. This stop-cock had no 

 hole, so that it might be turned quite round without opening any 

 communication between the external air and the inside of 

 the tube ; but there was a cavity in it into which the balls 

 could be put, and when the cock was turned round each ball 

 dropped in succession to the bottom of the stout tube. From 

 this perpendicular tube a small horizontal tube, soldered by the 

 blowpipe, proceeded, dipped into a mercurial trough, to convey 

 the gas evolved during the combustion into graduated flasks 

 filled with mercury, and ready to receive it. The bottom of the 

 tube being heated to a dull red heat, balls were dropped in suc- 



* Recherches Physico-Chimiques, ii. 265. 



