176 AIR AND LIFE. 



For instance, during the wars in India, 140 prisoners were one even- 

 ing at 8 o'clock shut up in a small room. Out of the number only 50 

 were still living at 2 o'clock next morning, and at daybreak only 23, all 

 dying. Again, after the battle of Austerlitz, out of 300 prisoners con- 

 fined in an ill- ventilated cellar, 2G0 died in a few hours through 

 asphyxia, induced by an excessive proportion of carbon dioxide. And 

 at the celebrated Oxford assizes (the "fatal" or u black" assizes in 1557), 

 the high sheriff and 300 other persons died suddenly in court from 

 asphyxia induced by the same means. It may be that in these cases 

 some other influence was also at work, and that some exhaled substance 

 similar to that which Brown-Sequard and d'Arsonval thought they had 

 detected, added its influence to that of carbonic acid; but the existence 

 of this substance has not yet been proved, although it seems probable. 



Other cases of poisoning by carbonic acid are met with in natural con- 

 ditions. Men and animals are occasionally killed by such gas, exhaled 

 by neighboring springs and accumulated in hollows or small valleys. 

 Such "death valleys" have been described by many travelers. No 

 plant is seen, not a blade of grass, not a shrub or tree. The soil is 

 bare, stony, and as if struck with death. Here and there a skeleton is 

 perceived bleaching in the sun — a skeleton of bird, mammal, or even 

 man. Ignorant of the fatal properties of the valley, animals or men 



required than the 16 to 20 cubic meters of air per individual per hour, that was 

 formerly considered as sufficieut. In the best ventilated hospitals of Paris 100 cubic 

 meters are provided, hut under normal conditions 60 are quite enough for persons in 

 good health. As a rule, the atmosphere of a room may he considered as vitiated as 

 soon as it begins to smell close. When this happens, however, it must not be con- 

 sidered as due to the smell of carbonic acid itself, which is scentless. The smell of 

 close air is due to organic substances — hitherto undefined, or only partly known — 

 which are exhaled by men and animals, and probably more by the skin and its 

 impurities than by the lungs themselves, and generally the amount of these sub- 

 stances is considered as roughly proportional to the amount of carbon dioxide met 

 in the air. Smell is considered as indicating approximately the unhealthiness of the 

 atmosphere as regards respiratory purposes, and is a safe enough criterion. When 

 a room becomes close, it should be thoroughly ventilated, and in suchcase a draft 

 should always be established, two doors or windows, on different sides of the room, 

 being opened. One is not enough ; both are required in order to completely expel 

 the close air and replace it by pure. Generally servants — and masters as well — are 

 content with imperfect ventilation. Such is especially the case in winter, when air 

 is often vitiated by the presence of a gas, carbon monoxide, which is given off in very 

 small quantities by different heating apparatus, stoves especially. Although this gas 

 is never present in any great quantity, it is a source of considerable danger; and in 

 countries where slow-combustion stoves are used, it is each year the cause of many 

 deaths. Carbon monoxide has even greater affinities for hemoglobin than has oxygen, 

 it therefore combiues with it and thus there is no place left in the blood corpuscles for 

 oxygen, and the blood then carries no more of the latter gas to the cells and tissues 

 of the body. This gas is also found iu the air of mines, but in the open air is not 

 met with, or exists in such small quantities that it can not be detected by present 

 methods. 



