AND ITS EFFECTS UPON ANIMAL LIFE. 17 



above. Mice and sparrows were used. The details ai"e given in the Appendix 

 IV., 1, nii<l the results in Table G. It was found inqiossible, by Hammond's 

 method, to absoib all the carbonic acid produced by an animal, and it will 

 be seen l)y Table G, that at the time of death of tlie sparrows, the carbonic acid had 

 increased until it formed from 12.27 to 14.08, or an average for eight experiments 

 of 13.24 per cent, of the air, while the oxygen had diminished to from 3.25 to 5.61, 

 or an avei'age of 4.67 per cent, of the aii-. The symptoms observed were those pro- 

 duced by insufficiency of oxygen, and there was no evidence that death was due to 

 organic matters in the air. The duration of life in the animals confined was from 

 three to six hours, being much longer than that reported by ILunmnnd using a 

 slightly smaller vessel, viz. less than one hour, and coi'responds to the results re- 

 ported by Sanfelice (33), who found that the auimuls lived fi-om six to seven hours. 

 When the expei'iment was so modified that all the carbonic acid was removed from 

 the air breathed by the animal — as described in the appendix, the animal did not 

 die in seven hours, although the percentage of oxygen had been reduced to 18.35, 

 as shown by Table H in the appendix. These experiments, therefore, furnish no 

 evidence of the existence of an organic poison in the expired air, but the method of 

 absorbing carbonic acid by an alkali is said by Brown-Sequard and d'Ai'sonval 

 (22) to change the organic poison which they claim to be present, and hence these 

 experiments are not conclusive on this point. 



A series of expei'iments was also made upon mice and sparrows to determine 

 the time required to produce death by asphyxia when the animal is confined in a 

 jar of known capacity, when no provision is made for removing carbonic acid and 

 moisture, or for supplying fresh air, and also to determine the proportions of carbonic 

 acid and of oxygen existing in the enclosed air at the time of death. In connec- 

 tion with these experiments it was also sought to determine the influence which 

 high or low temperatures of the air would have on the result. The data 

 derived from these experiments are shown in Table I in the Appendix. 



A mouse weighing 21 grams, placed in a jar of 1000 c. c. capacity at a tem- 

 perature of 30 ° C, lived four hours ; in a jar of 2000 c. c. capacity a similar mouse 

 lived seven and a half hours ; in one case when the room tempei'ature was 25.5° C, 

 in another case when the room temperature was 5 ° C. In the first case death 

 occurred when the amount of carbonic acid was 12, and that of the oxygen 8.6 per 

 cent, of the mixture; in the second case, the proportions were 13.2 per cent, of car- 

 bonic acid and 6.4 per cent of oxygen ; and in the third case, 10 per cent, of car- 

 bonic acid and 9.2 per cent, of oxygen. There are considerable differences in suscep- 

 tibility to the effects of an impure atmosphere in individual mice, but when a mouse 

 is placed in a closed jar containing ordinary atmospheric air, the time required to 



