524 On the Quantity of Carbon in Carbonic Acid, 



Correction for pressure. 

 30 : 30-2 : : 51-69 : 52-03. 



The volume, therefore, at mean pressure and temperature, 

 would have been 52-03 cubic inches. 



We now lighted a lire in the small black lead furnace 

 under the platina tube, and as soon as it became red hot, 

 opened the cocks and passed the gas from No. 1 to No. 2, 

 when the charcoal entered into vivid combustion, and heated 

 the platina tube white hot. The operation was repeated 

 many times during six or seven minutes, by pressing alter- 

 nately "upon the glasses of the gasometer. Not the least 

 Hash of lidit was observable in the dass connectina; tubes 

 G G, nor the smallest appearance of moisture. The fur- 

 nace being removed, the lube was now cooled by the appli- 

 cation of wet cloths ; aud when all was reduced to the tem- 

 perature of the room, we pressed upon the glass of gasome- 

 ter No. 2, so as to force all the gas into No. 1. The cock 

 below being closed, we tried the tubes, &c. and found them 

 perfectly air-tight. We next unscrewed the tube and took 

 out the platina tray ; but it only contained a light white ash, 

 somewhat resembling the shape of the pieces of charcoal, 

 and weighing only -02 of a grain. On observing the regis- 

 ter of No. 1, it indicated exactly the quantity of gas that wc 

 began with, so that although 3-98 grains of charcoal had 

 been dissolved, the volume of gas was unaltered by it ; a 

 circumstance which had been remarked before by Lavoi- 

 sier. The small receiver R was now nearly full of mercu- 

 ry ; the communication with the gasometer being opened, 

 the large glass receiver was gently pressed upon, until seve- 

 ral cubic inches were forced through the receiver R, and 

 tube K, in order to clear the latter of common air. This 

 being done, on trying our gas with the eudiometer and Wmn 

 water, 56 parts were absorbed out of 100. These of course 

 were carbonic acid gas ; the test for oxygen absorbed 41, 

 and a residuum of 3 was left, which was exactly what we be- 

 gan with. This is a striking proof that nothing but carbonic 

 acid was produced in the experiment. 



100 : 56 : : 52-03 : 29-13. 

 Then 29*13 cubic inches of carbonic acid gas were produced. 



100 



