898 Experiments 



Experiment DXCVIII. February 13. Collared adder, placed in a 

 bell of 875 cc, with air with 77% of oxygen. 

 Dies February 21. 

 The air contains 13.5% of carbonic acid, and 61% of oxygen. 



Experiment DXCIX. March 16. Frog placed in a bell of 400 cc, 

 with pure oxygen. 



Dies March 23. The temperature was from 6° to 7°. 

 The air contains: O, 81, CO, 17. 



Experiment DC. March 16. Frog placed in a bell of the same di- 

 mension, in the same air as the preceding. 

 Dies March 25. 

 The air contains: O, 84, CO, 13.7. 



For others, to the superoxygenated air there was added in ad- 

 vance a certain proportion of carbonic acid. 



Experiment DCI. August 3. Gray lizard, placed at 4: 15 in a bell 

 containing 570 cc. of an atmosphere with 78.9% of oxygen, the rest 

 being nitrogen. 



August 4. Yawns a great deal, is very uneasy; the distress keeps 

 increasing, and the animal dies August 6, about 2 o'clock (70 hrs.). 



The temperature varied from 23° to 29°. 



There is 15.7% of CO, in the bell. 



Experiment DCII. August 3. Gray lizard, placed at 5:15 in a bell 

 containing 550 cc. of an atmosphere with 90% of oxygen and 10% 

 of CO,. 



August 4. Still somewhat sensitive at 4 o'clock in the evening; 

 found dead at 9 o'clock (about 28 hours). 



The temperature varied from 23° to 29°. 



The air contains 16% of CO,. 



Experiment DCIII. August 3. Frog placed at 5:45 under a bell of 

 550 cc. containing 90% of oxygen and 10% of CO,. 



August 4. 10 o'clock in the morning, seems to be hardly breath- 

 ing. Dies at 2 o'clock (lived 20 hours). The temperature of the lab- 

 oratory varied from 23° to 29°. 



There is 17% of CO, in the bell. 

 For others the experiment was made in compressed air. 



Experiment DCIV. July 28. Temperature 22°. Two frogs are 

 placed at 3 o'clock in the small Seltzer water receiver ,and subjected 

 to a pressure of 5 atmospheres. 



Nothing special during the two or three days following. 



August 1. 1 o'clock. Are evidently very sick. 



Die about 3 o'clock. 



The air contains 3.2% of CO,; the tension therefore is 3.2 x 5 = 16. 



And so, by one or another of these multiple methods, we see that 

 the lethal tension of carbonic acid for reptiles varies between 13.5 



