HYGIENE OF RESPIRATION AND VENTILATION 173 



The Silvester method of artificial respiration is shown in 

 Figs. 90 and 91. 



In case of asphyxiation, or suffocation by gases or by electric 

 shock, the same procedure should be followed, except that it is 

 not necessary to take special steps for emptying the lungs. 



Under the supervision of the United States Bureau of ^Nlines 

 squads of miners are instructed in the resuscitation, or reviving, 

 of people who become asphyxiated by gases or by electric 

 shock. This bureau conducted a series of experiments to de- 

 termine which of the mechanical resuscitating devices was best, 

 for various purposes. It was found that more reliance could be 

 placed on quick action by men who understood how to establish 

 respiration than on most of the machines. It is always safer to 

 begin work by hand than to wait for the best machine. 



From experiments conducted on various animals we now 

 know that our breathing is influenced by the amount of carbon 

 dioxid in the blood. When you run for a while the muscle cells 

 work harder and oxidize more sugar and use up more oxygen 

 and give off more carbon dioxid. The excessive carbon dioxid 

 in the blood acts upon certain nerves, which forces deeper 

 breathing. That is why we breathe faster when we exert our- 

 selves. A very useful application of these facts has recently 

 been made. When a person is overcome by gases or fumes, air 

 with a certain amount of pure carbon dioxid is forced into the 

 lungs. This gas, acting in the same way as carbon dioxid that 

 results from overexertion, forces deep breathing and so helps 

 to restore normal breathing again. By this method firemen who 

 had been suffocated at a fire were quickly restored so that they 

 were able to go on with their work immediately. 



141. Poisonous fumes. With the increasing use of internal- 

 combustion engines, and especially of automobiles, there has 

 come a serious danger of poisoning by carbon monoxid (CO). 

 Like carbon dioxid (CO2), this gas combines with the red pig- 

 ment of the blood corpuscles ; but, unlike carbon dioxid, it 

 brings about chemical changes that are not reversed when 

 oxygen is present. Every year many persons die as a result of 



