RESPIRATION 



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The longer any part of the body takes to saturate, the longer 

 will it also take to desaturate to the point at which it is safe to 

 reduce the pressure to normal. But if we know the pressure and 

 duration of exposure, we can now calculate a safe rate of further 

 decompression after the initial reduction of total pressure to half 



no 



12 3 4 5 



Multiples of the time required to produce half-saturation. 

 Figure 89. 

 Curve showing the progress of saturation of any part of the body 

 with nitrogen after any given rise of pressure. The percentage 

 saturation can be read off on the curve, provided the duration of 

 exposure to the pressure, and the time required to produce half satu- 

 ration of the part in question, are both known. Thus a part which 

 half saturates in one hour would, as shown on the curve, be 30 per 

 cent saturated in half an hour, or 94 per cent saturated in 4 hours. 



has been carried out : for we can calculate the rate at which nitro- 

 gen is being carried away from parts which saturate and de- 

 saturate quickly, or from those which do so slowly. We can thus 

 regulate the rate of decompression so that no part of the body 

 is at any time supersaturated to such an extent as to cause risk of 

 bubble formation. In this way tables were calculated for regu- 

 lating the rate of decompression of divers and other workers in 

 compressed air. For the sake of convenience the decompression 



