Action of Carbonic Acid 925 



And that is easily understood, I said: carbon monoxide acts like 

 a simple hemorrhage or an asphyxia in nitrogen, by suppressing 

 the oxygen of the blood, whereas carbonic acid poisons the tissues 

 themselves. Only if the experiment is stopped before the animals 

 are quite dead, the frog with the C0 2 recovers quite quickly, but the 

 one with the CO dies, on the contrary, since it is definitely de- 

 prived of its red corpuscles. 



It seemed to me interesting to try to determine the proportion 

 of carbonic acid dissolved in the water, which would be incom- 

 patible with the life of fishes. Here are the details of the experi- 

 ment: 



Experiment DCXXXI. May 22. At 12:15. Golden carp of the same 

 size are immersed in flasks with stoppers, full of a well aerated water 

 to which have been added growing proportions of water saturated 

 with carbonic acid so that 



A contained pure water (which holds in solution 4.4 volumes of 

 CO. per 100 volumes of liquid) 



B contained water with 11% of C0 2 

 C contained water with 18% of CO, 

 D contained water with 30% of C0 2 

 E contained water with 45% of C0 2 . 



At 12:35, fish E was breathing very feebly, whereas B was breath- 

 ing more strongly than A. 



12:45. E is on its side, very sick; D is evidently sick too. 

 1:05. E is dead; D, very sick; C and B are breathing with diffi- 

 culty; D dies about 10 o'clock in the evening. 

 The next day, A, B, and C are still alive. 



The proportion of free C0 2 which is rapidly fatal is therefore 

 in the neighborhood of 30%. That is much above the quantities 

 which exist in all waters not charged with saline elements. 



Carbonic acid manifests its action not only on animals, but also 

 on plants. 



In a medium with high C0 2 content, green plants die rapidly, 

 when we prevent the light from permitting them to decompose 

 the dangerous gas rapidly. 5 



Germination is delayed and checked, when the proportion of the 

 gas is sufficient; the seeds themselves may be killed by it. As an 

 example of these facts, I quote the two experiments following: 



Experiment DCXXXII. April 8. Sowed, under a large bell of 11 

 liters, a few seeds of barley and of cress upon well moistened paper. 

 The bell is filled with a mixture containing: 2 16; CO, 20; N 64. 



May 2. Nothing has developed; the air of the bell contains: 

 2 12.9; C0 2 29. I leave the seeds in the open air; on May 7, some 

 shoots appear, and on May 20 all has sprouted well; the barley already 

 measures 12 cm. 



