392 THE COMPOSITION OP EXPIRED AIR. 



Smith (9) employed a lead chamber in his investigations upon the 

 question whether human lungs give off any poisonous agent other than 

 carbonic acid. He found the pulse to fall from 73 to 57 beats per 

 minute, and the number of respirations to rise from 15.5 to 24, as the 

 carbonic acid in the atmosphere increased from 0.04 to 1.73 per cent 

 during four hours. When the proportion of carbonic acid rose to 3 per 

 cent there appeared great weakness of the circulation with slowing of 

 the heart's action, and great difficulty in respiration. He believed tbat 

 these results should be attributed to other conditions rather than to 

 the excess of carbonic acid, because he found later that it was only 

 when lamps became dim in an atmosphere — indicating a proportion of 

 about 10 per cent of carbonic acid iiresent— that the respiration became 

 difficult. 



Seegen and Nowak, in 1879 (10), believed they had demonstrated the 

 presence of poisonous organic matter in the expired breath by passing 

 it over red-hot cupric oxide, but the quantity found was so small that 

 they failed to determine its exact nature and properties. 



Hermans, in 1883 (11), was unable to detect any organic matter in the 

 atmosphere of a tin cage in which several persons had been confined 

 for a number of hours, and found that an atmosphere containing from 

 2 to 4 per cent of carbonic acid and 15 per cent of oxygen was not toxic. 



Brown-Sequard and d Arson val, in 1887 (12), reported that the air 

 expired by men and dogs in a state of health has the power of produc- 

 ing toxic phenomena, citing three series of experiments on rabbits where 

 such phenomena were observed. In the first series they injected into 

 the vascular system of a rabbit 4 to 6 c. c. of water obtained by inject- 

 ing from 15 to 25 c. c. of pure filtered water into the trachea of a dog. 

 In a second series from 6 to 7 c. c. of a liquid obtained by condensing 

 the moisture in the exhaled breath of a man were injected into the aorta, 

 or into a vein, of a rabbit. In the third series from 4 to 6 c. c. of a liquid 

 obtained by condensing the moisture in the exhaled breath of a trache- 

 otomized dog were used. The condensed liquid thus obtained was fil- 

 tered and then injected either into the jugular vein or the carotid artery. 



The symptoms observed were dilatation of the pupils, increase of the 

 heart beat to 240, 280, or even 320 per minute, lasting for several days 

 or even weeks. The temperature remained normal, the respiratory 

 movements were generally slowed, and usually there was observed par- 

 alysis of the posterior members. Choleraic diarrhea was invariably 

 present. Death usually took place in a few days, or at the farthest in 

 four or five weeks. As a rule, it appeared that larger doses caused 

 labored respiration, violent retching, and contracted pupils. A rapid 

 lowering of temperature, 0.5° to 5° C, was sometimes observed. The 

 appearances that presented post-mortem were much like those observed 

 in cardiac syncope. 



They believed they had discovered a volatile organic poison in the 

 exhaled breath and the moisture condensed from it. This rjoison they 



