Herbst, from his experiments, concluded, that a healthy adult of average size should in an ordinary inspiration inhale from, 20 to 25 Parisian cubic inches (24.211 to 30.263 English cubic inches), and exhale the same quantity in expiration; while an individual of a feebler constitution of body should inhale from 16 to 18 Parisian cubic inches (19.368 to 21'789 English cubic inches).rf Valentin gives as the result of his experiments upon seven males between and 33 years of age, that the quantity of air expired in ordinary up to a somewhat quickened respiration, ranges between 239.3 and 1567.7 cubic centimetres (14.603 and 95.672 English cubic inches), the average of which was 653'11 c. c. (40.081 English cubic inches)4 Vierordt§, in re peated experiments upon himself, ascertained that at each expiration, when in a state of rest, he expelled from the lungs on an average 507 cubic centimetres (30.940 English cubic inches), and that the average of the five high est values was 699 c, c. (42.657 E. c. inches), and of the lowest 177 c. c. (10.801 E. c. inches).11 Bourgery, from experiments upon fifty males and twenty females*, with the view of ascertaining the relation between the inti mate anatomical structure of the lungs, and the functional capacity of these organs in the two sexes, concludes that the volume of air required by- an individual in ordinary re.spira don augments gradually with the age, being least in youth (from 5 to 15 years), in conse quence of the extreme vascularity of the lungs ; increased from 15 to 30 years of age, in consequence of the proportional dIrninution in the closeness of the pulmonary capillary network of blood vessels ; and to a much greater amount in old age, in consequence of the more rapid diminution of the extent of the respiratory membrane, which bins to take place after the lungs have arrived at their full development, or the age of 30.
It is ob.ious that we are not yet in posses sion of data to enable us to venture upon an estimate of the average quantity of air in spired and expired at an ordinary respiration, when the body is at rest and the mind undis turbed, at different periods of life, in the two sexes, and in different physical configurations of body. It is equally apparent that this is liable to considerable variation, and that the different results obtained by most experi menters,—setting aside those where an obi-L. ously faulty method was pursued,— depends as much upon the inherent differences in the extent of the respiratory movements in the individuals experimented upon, as upon errors in the mode of experimenting, and that the chief e_rror committed by some of them consists in deducing, averages from tbe few and insufficient experiments performed by themselves, and casting doubts upon the results obtained by others, simply because they do not accord with their own, It also necessarily follows that we are not in a posi tion to form an estimate of the average quan tity of air which passes out and in from the lungs in twenty-four hours in ordinary respi ration. Vierordt*, from experiments on his own person, calculates that he respires 603-4 cub. cent. (36S.074 English c. inches) of atmospheric air in one minute, or 8,6SS,960 cub. cent. (530,026-560 Eng. c. in.) in the twenty-four hours. As, howe‘er, the respi ration is rendered niore energetic by speaking, walking, &c., any- estimate drawn, as this by Vierordt is, from observations made when the body was in a state of rest, will be, as he was aware, too low ; and proceeding on some of the results of Scharling's experiments, he makes allowances for this increase, and esti mates the quantity of air respired in the twerm-four hnurs at 624,0S7-401 English cubic inches. Valentin+ calculates that in his own person, after making allowances for temperature and watery vapour, he respires 4.69-9755 litres (2S6S1 1948 English cubic inches) in an hour, and 688.34-S-6761 Eng. cubic inches, or nearly 398 cubic feet of atmospheric air in the twenty-four hours.T.
The quantity of air drawn into the lun2s during quickened or furred inspiration, and again evened during expiration, also varies very considerably in different individuals of the same aue. Sir H. Davy§, in many ex periments upon himself, ascertained that at a temperature from 58° to 62° Fahr. he threw
out of his lungs by a full forced expiration, spiration about 135 ; in a state of natural expiration about 118 ; and in a state of forced expiration 41.* Good wynt, in his experiments on the capacity of the lungs upon four indi viduals after a natural death, found the resi dual air in the lungs to vary from 90 to 125 cubic inches, giving an average of 109, and as the chest, after a natural death, may be re garded as in a state of natural or ordinary expiration, this result differs very little from that of Davy. Allen and Pepys t, in one experiment on the capacity' of the lungs in a middle-sized man after death, also obtained a little more than 100 cubic inches of residual air. Vierordt§ supposes that the residual air in the lungs, after the deepest expiration, is about 600 cub. cent. (36-600 Eng. cub. in.), which differs but little from the estimate of Davy.
Herbst ji made experiments upon 11 males, between 16 and 30 years of age, with the view of ascertaining the quantity of air drawn into the lungs in forced inspiration. The smallest quantity observed was in a Jew aged 22, of small stature, and feeble muscular sys tem. He inspired between 60 and 70 Parisian cubic inches (between 72-635 and 84-738 Eng. cub. in.) after an ordinary expiration ; be tween 102 and 118 (123-476 and 142-844 Eng. cub. in.) after a strong expiration ; and 120 (145-266 Eng. cub. in.) after the strong est expiration. The largest quantity inspired was by a young man of 25 years, of middle height with a broad chest and large and powerful muscles, who inspired by a forced inspiration, about 1693- English cubic inches, without any previous voluntary expiration; about 2901 after a strong expiration ; and about 290t or 295+ after the strongest ex piration. A yeiung man of 23 years of age, 6 feet high, with broad chest and large mus cles, inspired, without any previous voluntary expiration, 121 English cubic inches, and 280-72 after the fullest expiration. The quan tities of air drawn into the lungs in forced inspiration in the other eight rnales, were in termediate between the highest and lowest mentioned above, and the average was about 202 English cubic inches.'ll Herbst also sa tisfied himself that the lungs of females have a considerably smaller capacity for air than those of males. He states that robust fe males, about the age of 30, may inspire vvith out a previous voluntary expiration, 721 English cubic inches, after an ordinary ex piration nearly 109, and after the strongest expiration, from about 157+ to 174+ English cubic inches.* Herbst had an opportunity, in two of these experiments on males, of ascertaining the effects of tight clothing on the extent of the respiratory movements. One individual who inspired 128 and another 116-16 English cubic inches, without a pre vious expiration after the clothes were loos ened, could before this only inspire 96-80 and 601 English cubic inches. t The rnost extensive experiments by far, made with the view of ascertaining the quantity of air which can be thrown out of the lungs by forced expiration, after the deepest inspiration, are those of' Mr. Hutchinson4 These experi ments were performed upon 1923 rnales, and they were made to breathe into an instrument constructed for the purpose, and which he has called a spironzeter, He has inferred t'rom the data he has collected on this point, the rule, that " for every inch of height (from 5 feet to 6) 8 additional cubic inches of air at 60° Fahr. are given out by a forced ex piration ;" so that he believes that from the height alone of an adult male, he can tell what quantity of air he should breathe to constitute him healthy, and that this method may be turned to important practical appli cation in ascertaining disease of the lungs, 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).