342 



RESPIRATION. 



under circumstances where the ordinary me- 

 thods fail. Mr. Hutchinson has given the 

 following table to show the quantity of air 

 expelled by the strongest expiration after the 

 deepest inspiration for every inch of height 

 between 5 and 6 feet, as ascertained by actual 

 experiment (column 1) by his spirometer, and 

 as calculated according to the rule mentioned 

 above (column 2). 



Mr. Hutchinson has found that two other 

 conditions of the body besides the height, 

 regulate the quantity of air that passes to 

 and from the lungs in forced voluntary respi- 

 ration, and these are age and weight. He 

 states that weight does not affect the respira- 

 tory power of an individual of any height 

 between 5 feet 1 inch and 5 feet 11 inches 

 until it has increased 7 per cent, above the 

 average weight of the body in persons of 

 that height, but beyond this it diminishes in 

 the relation of 1 cubic inch per pound for the 

 next 35 pounds the limit of the calculation. 

 In males of the same height the respiratory 

 power is increased from 15 up to 35 years of 

 age, but from 35 to 65 years it decreases 

 nearly 1 cubic inch for each year.f Bourgery 



* Med.-Chir. Trans, vol. xxix. p. 237. Experi- 

 ments to ascertain the quantity of air that may be 

 inspired or expired in forced respiration have also 

 been performed by Hales (Statical Essays, vol. i. 

 p. 243), Jurin, Menzies, Goodwyn, Dr. Bostock (Sys- 

 tem of Physiology, p. 316. 1836), Dalton (Opus cit. 

 p. 26), Thomson (Animal Chemistry, p. 610. 1843), 

 Valentin (Opus cit. p. 540), and Thackrah (The 

 Effects of Arts, Trades, and Professions, &c. on 

 Health and Longevity, 2nd edit. pp. 27, 30, 64, 76, 

 98, 181, and 182). These experiments, however, are 

 neither sufficiently numerous several of them hav- 

 ing been performed on a single individual only, 

 nor are they accompanied with the details necessary 

 to enable us to contrast them with those of Mr. 

 Hutchinson ; but the results obtained in the greater 

 number of these do not differ much from those of 

 Mr. Hutchinson upon men of middle stature. Va- 

 lentin experimented on six males, and his estimates 

 rest on the questionable supposition that the ex- 

 pired air is fully saturated with moisture. Thom- 

 son experimented on 11 males and 1 female, from 

 14 to 33 years of age ; and Mr. Thackrah's experi- 

 ments were considerably more extensive, and were 

 made on individuals of different trades and pro- 

 fessions. 



f Mr. Hutchinson has not observed any direct 

 relation between the circumference of the chest and 

 the respiratory power or what he terms the vital 

 capacity. According to the experiments of Herbst 



concludes from his experiments already re- 

 ferred to, that the measure of respiration (by 

 which he apparently means the quantity of 

 air which may be drawn into the lungs by a 

 forced inspiration) is greater the younger and 

 thinner the person is ; that its maximum in 

 both sexes occurs at the age of 30 ; that the 

 relation of a forced and ordinary respiration 

 diminishes with the age of the individual, 

 being, he says, from 1 to 12 at three years of 

 age, as 1 to 10 at fifteen, as 1 to 9 at twenty, 

 as 1 to 3 at sixty, and as 1 to i or % at eighty 

 years ; whence it follows that in youth there 

 is an immense respiratory power in reserve 

 for any violent exertion, while in old age the 

 individual under such circumstances is at 

 once out of breath.* 



Changes upon the atmospheric air in respi- 

 ration. One of the most obvious changes, 

 under ordinary circumstances, upon the air 

 that enters the lungs in respiration is an 

 increase of its temperature, and consequently 

 an augmentation of its bulk. As a quantity 

 of water is readily supplied by the fluid secre- 

 tions of the inner surface of the air-passages, 

 and by the blood in the pulmonary capillary 

 blood-vessels, this augmentation of the tem- 

 perature of the air is also necessarily attended 

 by an increase of its watery vapour, and con- 

 sequently by an additional increase in its bulk 

 and elasticity. The expired air, therefore, 

 contains more caloric, more watery vapour, is 

 more elastic, and is of less specific gravity 

 than the inspired air. Valentin performed 12 

 experiments on his own person by breathing 

 through an apparatus invented by Brunner 

 and himself, to ascertain the temperature of 

 the expired air, and he obtained the following 

 results. In breathing atmospheric air of a 

 temperature varying from 8'5 to 33'5 Reau- 

 mur (51-125 to 107-375 Fah.), he observed 

 a difference of 1'75 R. (3'937 F.) .in the 

 temperature of the expired air. While breath- 

 ing in the lowest temperature, viz. 51 * 125 F., 

 the temperature'of the expired air was 96' 687 

 F., and was warmer than the inspired air by 

 45*562 F. ; and when breathing in the 

 highest temperature the expired was colder 



(Opus cit. p. 104), and Mr. Hutchinson, the mode 

 of determining the quantity of air which the lungs 

 are capable of containing during life in any parti- 

 cular case, by measuring after death the quantity 

 of air which can be thrown into them by inflation, 

 is fallacious. This is probably chiefly due to the 

 congestion of the depending parts of the lungs by 

 blood, so frequently found after death. Both Herbst 

 and Mr. Hutchinson have performed experiments to 

 show the extent to which the quantity of air in forced 

 respiration is diminished in phthisis. 



* Among the proofs of these conclusions, ad- 

 vanced by Bourgery, it is stated by him that the 

 measure of respiration of a boy of 15 years of age is 

 2 litres (122-054 Eng. cubic inches), and a man of 

 80 years 1-35 litre (82-386 Eng. cubic inches) : that 

 while a boy of 10 years and a man of 80 inspire by 

 a forced inspiration the same quantity of air, viz. 

 1-35 litre, yet the ordinary respiration of the former 

 is only 1 decilitre (6-102 Eng. cub. in.), while that 

 of the latter is 9 decilitres (54-918 Eng. cub. in.) ; 

 so that with a mass three times smaller, the child 

 possesses an energy of hematose eight times greater. 



