106 



air than is given out at several expirations*. By a very 

 different mode of experiment, we find Mr Davy to 

 conclude that his lungs, after a forced expiration, 

 contain only 32 cubic inches of air, when it is re- 

 duced to the temperature of 55, but which, by the 

 heat of the lungs, and saturation with moisture, are 

 increased to 41 cubic inches; and, after a natural 

 expiration, they contained 118 cubic inchest ; so that 

 the difference between the two states of natural and 

 forced expiration is 77, which is somewhat more than 

 Dr Menzies allows, who remarked that many men, 

 after an ordinary expiration, could still expel from their 

 lungs 70 cubic inches of air{. Mr Davy adds, that his 

 estimate of 1 1 8 cubic inches, as the capacity of the 

 lungs after natural expiration, agrees very well with 

 that of Dr Goodwyn, who makes it about 1O9{; and, 

 on the supposition that the general debility which 

 precedes the ordinary extinction of life, so weakens 

 the expiratory muscles, as to disable them from ma- 

 king so complete an expulsion of the air, as they can 

 effect when in health and vigour, the agreement is 

 very striking ; for nearly the same quantity of air 

 would, in that case, remain in the lungs at the pe 

 riod of natural death, as after that of ordinary expi- 

 ration. 



88. Dr Bostock conceives, that Dr Goodwyn's 

 estimate of 109 cubic inches of air remaining in the 

 lungs after complete expiration, is not very remote 



* On Insensible Perspiration, p. 97. 



f Researches, p. 409. & 4-10. 



J Dissertation on Respiration, p. 31. Ibid. p. 411. 



