BAD AIR AND BAD HEALTH. 815 



called ozone, which is rarely found in the air of towns. Of this 

 gas-mixture (which we call air) we breathe enormous quantities. 

 Of it we breathe in the twenty-four hours, according to Prof. M. 

 Foster, over 2,600 gallons, that is about 425 cubic feet; and as 

 it returns from our lungs the proportions of the mixture are 

 changed, the oxygen being reduced, and the carbonic acid in- 

 creased.* But in all ordinary cases the quantity of oxygen in a 

 room in which people are meeting is only slightly decreased, while 

 the increase of the carbonic acid is not sufficient to cause bad 

 effects. How, then, arises the mischief ? 



The truth is that, in taking air into the lungs and breathing it 

 out again, we breathe out with it certain organic poisons. About 

 the existence and presence of these poisons there can be no doubt, 

 though very little is known about their nature. Of them Dr. 

 Foster writes (page 552) that they may be formed in the lungs, or 

 may be products of putrefactive decomposition allied to a class of 

 poisons known as ptomaines, which are found in the system. Dr. 

 A. Ransome (Health Lectures, 1875-76, page 160) says : 



The aqueous vapor arising from the breath, and from the general surface of 

 the body, contains a minute proportion of animal refuse matter, which has been 

 proved, by actual experiment, to be a deadly poison. ... It is this substance that 

 gives the peculiar, close, unpleasant smell which is perceived on leaving the fresh 

 air and entering a confined space occupied by human beings or other animals, . . . 

 and air thus charged has been fully proved to be the great cause of scrofulous or 

 tubercular diseases, and it is the home and nourisher of those subtle microscopic 

 forms of life that have lately become so well known under the title of germs of 

 disease, or microzyms. It is probably the source of a large part of that increase 

 of mortality that seems inevitably to follow the crowding together of the inhabit- 

 ants of towns. 



Galton says (Our Homes, page 497) : " This organic matter 

 (given off from the lungs), on an average, may be estimated at 

 thirty or forty grains a day for each adult " ; f and both Dr. Car- 

 penter and Sir Douglas Galton notice that if breath be passed 

 through water (and then kept in a closed vessel at a high tempera- 

 ture), putrefaction is set up, and a very offensive smell is given off. J 



* It must be remembered that the act of breathing consists in bringing the blood of 

 the system in contact with air, through a delicate membrane in the lungs. Here an ex- 

 change takes place — oxygen being yielded up from the air to the blood, and carbonic acid 

 from the blood to the air. 



f We do not know on what exact grounds this calculation rests. 



X Foster (p. 552) states that " when the expired air is condensed . . . the aqueous 

 product is found to contain organic matter, which, from the presence of micro-organisms, 

 ... is very apt rapidly to putrefy." L. P. writes : " If a globe be filled with ice and 

 taken into a close, badly ventilated room, the dew which forms outside is found to be con- 

 taminated with these organic impurities." L. T. writes: ''It is more than likely that it is 

 this animal poison which is the direct cause of typhus fever as that follows overcrowding 

 with mathematical precision." 



