322 On the QumU'itij of Carbon in Carbonic Acid, 



Correcfion for pressure. 

 30 : 29-'15 : : 49-94 : 49-02. 

 The quantity of oxygen at the mean would therefore be 

 49-02 cubic iujhes. 



100 : 41 : : 49-02 : 20-09 

 Tho carbonic acid gas produced was therefore 20"09 cubic 

 inches. 



100 : 47-26 : : 20-09 : 9-49 

 and this carbonic acid weighed 9-49 grains. 

 Now the coal in the tray had lost 3-2 grains ; but as 

 the whole of this was not carbon, but part of it volatile 

 saline matter, See, we shall endeavour to estimate the 

 carbon by the experiment on plumbago. When 13-35 

 grains of carbonic acid contained 3-80 grains of carbon, 

 13-33 : 3-80 : : 9-49 : 2-70. 

 The quantitv of carbonic acid produced in this experiment, 

 therefore, contained 2-70 grains of carbon. 

 Loss 3-20 



Carbon 2*70 



Lraves '50 for volatile saline matter, See, 



So that, this being granted, the present experiment agrees 

 with the foregoing. 



In two of our fir^t experiments with box-wood-charcoal, 

 the calculations gave us in one case 29*75 parts of carbon in 

 100 of carbonic acid, and in the other 30-G3 ; but we were 

 not then fully aware of the absorption of water bv charcoal, 

 \yhich rendered the quantity of real carbon employed less 

 than indicated by the weight. Also in another experiment, 

 in which 4 -grains of diamond were consumed, the calcula- 

 tion crave us 29-96 per cent, of diamond in carbonic acid ; 

 but apprehending that a slight degree of inaccuracy had 

 crept into thi-; experiment, we have not detailed it with the 

 rest ; but wc h:ive thought it right to give a simple state- 

 ment of matters of fact; in no one instance have wc en- 

 deavoured to strain or acconmiodate these to suit any par- 

 ticular tKenry, being fully aware that every experiment, 

 carefullv made and faithfully recorded, will remain an im- 

 mutable truth to the end of time, while hypotheses are 



constantly 



