146 HISTORICAL INTRODUCTION TO CHEMISTRY CHAI-. 



Grains. Grains. 



Red lead 3>456 gave: Lead 3,108 



Charcoal 432 Unburnt charcoal... 342 



Fixed air 379* 



3,829* 

 Los, 58! 



Total 3,888 



The loss was due to the production of water, the com- 

 position of which was reckoned to be : 



Grains. 



Oxygen S l '5 



Inflammable air 770 



5875 



By subtracting the weight of hydrogen in the charcoa A and 

 the weight of oxygen used in burning it, these numbers give 



Grains. 



Weight of carbon burnt 432 - 342 - 77 = 82*30 



Weight of oxygen used to burn carbon 3,456 - 3,108 - 5 1*05 = 296*95 



Fixed air (carbonic anhydride) =379 '25 



The composition of carbonic anhydride is, therefore : 

 Oxygen = j 2-12 5%, say 72'1% 

 Carbon = 27-875% 27'9% 



The burning of spirit of wine, of olive oil, and of a 

 candle. Having established the composition of carbonic 

 anhydride, Lavoisier made use of his numbers to determine 

 the proportions of carbon and hydrogen contained in 

 various liquid and solid fuels. (" Combination of Oxygen 

 with Spirit of Wine," 1784; Works, II. 586-600.) 



The following numbers were obtained by burning a small 

 spirit-lamp over mercury in a bell-jar filled with air l (Fig. 33) 

 and supplied with oxygen from a second bell-jar inverted 

 over water. 



1 An explosion was always produced when the attempt was made to 

 burn the lamp in pure oxygen. 



