226 On the Quantity oj Carbon in Carlojiic Acid, 

 13-83 : 3-98 : : 100 : 28-77. 

 Th'-i', caIcuI:Uiiig by the oxvgen consumed, 100 grains 

 of carbonic acid gas contain 2S-77 charcoal. 



First Experimcvt on iyiamo7ul. 

 Thernionieter 56° Fahrcnhtit, barometer 30-20. 

 Our oxygen was made as in the former experiment: it 

 contained no carbonic acid ; and on being tried with the 

 impregnated green sulphate left a residuum of 3 parts 

 in 100. 



- Plaving selected nine of the clearest and most transparent 

 Brazil diamonds, we found tliev weighed 3*95 grains. 

 These were ranged in the platina trav, which was placed in 

 the tube, and the whole apparatus, adjusted as before, was 

 perfectly air-tight. The quantity of oxygen was 49-84 cu- 

 bic inches, as in the last experiment. The same precau- 

 tions were used to secure accuracy in the results as in the for- 

 mer experiment; and it would only be an unnecessary intru- 

 sion on the time of the Society to repeat them. The platina 

 tube was heated red-hot, and kept so for ten minutes ; 

 during this time the gas was repeatedly passed from one 

 gasometer to the other ; the tube did not become white hot, 

 as in the experiment with charcoal, because in this case the 

 combustion went on more slowly. When every thing was 

 cooled to the temperature of the room, the gas was all passed 

 into No. 1, by pressing down the receiver of No. 2, and the 

 volume was precisely the same as when we began the expe- 

 riment. On drawing out the tray uc observed that some of 

 the diamonds were reduced to a minute speck, and all of 

 them resembled opake white enamel : there was no discolo- 

 ration in the tray, nor any residual ash whatever ; the un- 

 consumed parts weighed 1-40 grains) the original weight 

 wa3 



3-9.5 

 1-46 



consequently 2-49 graiit? were consumed. 



We 



