562 



The fishes were left in the experimental bottles until dead, and 

 the time between introduction and death (dying time) is the basis of 

 a comparison of the relative resistances of the different species. Table 

 I is a summary of nine experiments in which four different concen- 

 trations of CO were used. 



Table T 



ShO'wing the relative resistance of several species of fishes to different concen- 

 trations of carbon monoxide. The concentration of the CO solution which flowed 

 through the experimental bottles is expressed in c.c. per liter. 



Species of fish 



Weight 

 offish 



in 

 grams 



CO 



1.2 c.c. 

 per liter 



CO 



3.8 c.c. 

 per liter 



CO 



6 c.c. 

 per liter 



CO 

 11.7 c.c. 

 per liter 



Moxostoma aureolvm 

 (Red-horse) 



Notropis Mennius 



(Straw-colored minnow) 



Pimcphales notatus 

 (Blunt-nosed minnow) 



Lepomis humilis 



(Orange-spotted sunfish) 



Lepomis cyanellns 

 (Green sunfish) 



Ameiurus melas 

 (Black bullhead) 



10—15 



2—4 



1—1.5 



2—6 



2—4 



20.5 



Ihr, 



1 hr., 55 min. 



5 hr., 40 min. 



6 hr., 10 min. 



45 min. 

 1 hr., 20 min. 



4 hr., 5 min. 



5 hr., 25 min. 



28 min. 



28 min. 



1 hr., 5 min. 



5 hr., 51 min. 



10 min. 



45 min. 

 4 hr., 5 min. 

 9 hr., 55 min. 



This table shows the high toxicity of water which contains even 

 small amounts of carbon monoxide in solution, and that stronger con- 

 centrations are proportionately more deadly. From the results of a 

 large number of similar experiments with COo (Wells, '13) it is 

 evident that a concentration of from 75-100 c.c. per liter of carbon 

 dioxide is required to equal the killing effectiveness of i c.c. per liter 

 of carbon monoxide. 



Water which contains lethal amounts of CO2 in solution will soon 

 lose its toxicity if exposed to the atmosphere for a comparatively 

 short time. The CO2 passes into the atmosphere until there is equilib- 

 rium between the gas in the atmosphere and in the water. Since the 

 atmosphere ordinarily contains but minute amounts of CO2, prac- 

 tically all of the gas will pass from the water; a solution containing 

 100 c.c. COo per liter will lose all but i to 2 c.c. per liter within two or 

 three hours. 



Normally, the atmosphere does not contain even a trace of CO, 

 and it would appear, therefore, that water containing small quantities 



