814 Experiments 



experimental device which allows one to keep the same oxygen 

 tension for the whole duration of the experiment and to dispose of 

 the carbonic acid as it is produced. 



For this purpose, I set up the apparatus pictured in Figure 74. 



It is a flask C (sometimes a bell) full of superoxygenated mix- 

 ture, proportioned in advance; at the bottom is a solution of potash 

 whose carbonic acid content has also been determined by means 

 of the mercury pump. A piece of meat, of known weight, is sus- 

 pended in it. The absorption of the oxygen and the fixation of the 

 CO. cause pure oxygen contained in a graduated test tube E to 

 enter the flask, bubble by bubble; a flask-valve P prevents the air 

 of the flask from flowing back in case its volume changes (tem- 

 perature, decrease of pressure, etc.). Several apparatuses are 

 placed thus which operate simultaneously and in identical condi- 

 tions, except the oxygen content of the air of the flasks. When the 

 experiment is over, analysis of the air of the flasks, the height of 

 the column of water in the test tube, and the quantity of C0 2 con- 

 tained in the potash give all the elements of the problem. 



But first I had to determine the degree of accuracy of this 

 experimental method. It was easy to make the test by using ordi- 

 nary air and making several simultaneous experiments under iden- 

 tical conditions. Here is the result. 



Experiment CCCCIX. January 18. Pieces of meat weighing 25 gm., 

 in 4 bells of equal size with ordinary air. 



January 22. The analysis of the potash solutions shows that the 

 production of carbonic acid was 195.8 cc; 197.8 cc; 204.8 cc. and 

 206.8 cc. 



The margin for error, then, for carbonic acid is about 5%. Let 

 us see now the results of the experiments. 



Experiment CCCCX. January 4. Pressure 745 mm.; temperature 

 16°. Piece of meat weighing 25 gm., at the top of 2 bells. 



A contains normal air. 



B contains air with 49.6% of oxygen. 



January 7. We find by analysis of the bells and the potash solu- 

 tions that: 



A has produced 232 cc. of C0 2 . 



B has produced 245 cc. of CO,. 



Experiment CCCCXI. January 24. Pressure 761 mm.; temperature 

 12°. Same experimental set-up, 3 bells. They contain: A ordinary 

 air, B air with 53% of oxygen, C air with 79.7% of oxygen. 



January 29. Analyzed the potashes. 



A produced 223 cc. of carbonic acid. 



B produced 270 cc. of carbonic acid. 



C produced 250 cc. of carbonic acid. 



