204 ADVANCED PHYSIOLOGY 



Breathing Carbon Monoxid. Carbon monoxid (CO) occurs 

 in all coal gas and all illuminating gas, sometimes escaping 

 from stoves which are badly constructed or have faulty 

 drafts. It is carbon monoxid which burns with the blue 

 flame often seen flickering over the surface of coal in a stove 

 or over burning charcoal. Haemoglobin will combine more 

 readily with carbon monoxid than with oxygen, so that if the 

 two are in the same air, carbon monoxid will unite with the 

 haemoglobin of the blood and oxygen will be excluded. If 

 this happens, the person concerned will die of suffocation 

 just as truly as if he had stopped breathing. 



It is easy to see why leaking gas pipes and stoves are un- 

 healthful. Gas pipes which enter sleeping rooms should be 

 watched with especial care, for from a very slight leak enough 

 escaping gas may accumulate during a night to suffocate a 

 sleeping person. There is danger, too, in leaving illuminal 

 ing gas turned low, for the flame may go out, blown by 

 gust of wind, or because the pressure is temporarily lowered 

 at the central plant, and the room be filled with gas. 



Carbon Dioxid in Respiration. In oxidation some of the 

 food products unite with oxygen and as a result another gas, 

 carbon dioxid, is formed. When, for example, a candle is 

 lighted, the tallow in it combines with oxygen, thus pro- 

 ducing carbon dioxid. If the tallow were eaten it would, in 

 a similar way, be united with oxygen in the body and the 

 same gas would result. Since this carbon dioxid is a waste 

 product, it must be removed from the body in some way and 

 the second phase of the respiratory process is concerned with 

 this elimination. 



Whenever any of the tissues of the body are active, some 

 food or tissue is combined with oxygen and a certain amount 

 of carbon dioxid is formed. The blood, as it flows througl 

 the capillaries of these tissues, absorbs this gas very much 

 it does oxygen in the lungs, and for the same reasons; i.e. 

 because the carbon dioxid pressure is high. By the time 



