•2 THK CO:^rPOSITION OF EXPIRED AIR, 



Bergey's notes on the results of Lis exi>erinients have been subniitteil to Drs. Bill- 

 ino-s anil Mitchell, who have suggested modifications or new experimunts as the 

 work ]i)rogressed. This leport is based on these notes, and accompanying tables and 

 charts, given in the Appendix. 



The etTects produced on animals and men by an atmosphere contaminated with 

 theii' exhalations, and with particulate matters derived from their bodies or tlicir 

 immediate surroundings, may be divided into acute and chi-onic. The acute effect 

 may be death in a few minutes or houis, as shown by the results observed in the 

 Black Hole of Calcutta, in the steamer Londonderry, and in many of the expeii- 

 ments referred to in this i-eport, or it may be simply great discomfort, especially in 

 those unaccustomed to such conditions. 



The chronic effects include the favoring of the action of certain specific causes 

 of disease commonly known as contagious, if these are present, and perhaps also a 

 general lowering of vitality. 



The statistical evidence collected by the English Barrack and Hospital Com- 

 mission (1) * as to the effects of insufficient ventilation upon the health of soldiers 

 in barracks, published in 1861, showed that men who live for a consideiable portion 

 of their time in badly ventilated rooms have higher sickness and death-rates than 

 have those who occupy well ventilated rooms, other conditions being the same; and 

 this has also been found to be true with i-egard to monkeys and other animals. It 

 is evident, however, that in a room occupied by animals or men there are many 

 sources of impurity besides the exhaled breath, and it is still a question whether the 

 expired air contains substances injurious to life, excluding carbonic acid. 



The widely divergent results obtained and conclusions reached by different 

 investigators during the last ten years as to whether the exhaled breath of men and 

 animals contains a peculiar volatile organic poison, have made it desiral»le to repeat 

 and vary such experiments in order, if possible, to settle this important point. The 

 chemical analyses of the air of overcrowded rooms, and the experiments upon 

 animals with various proportions of carbonic acid, made by many investigatoi's, 

 indicate that the evil effects observed are pi'obably not due to the comparatively 

 small proportions of carbonic acid usually found under such circumstances. 



It was shown by Leblanc (2), in 1842-43, that an animal <aii ])ic.itlie an 

 atmosphere containing as much as 30 per cent, of carbonic acid for three-quarters of 

 an hour, pi'ovided that the percentage of oxygen was 70, and then quickly recover 

 from the depression induced by this mixture after removal to the normal atmos- 

 phere. He also demonstrated that under the conditions in which the quantity of 



* The numbers in parentheses refer to the bibliographical list appended to this report. 



