1870.] 



on the Human Economy. 



521 



235704 235-704 00( , 10 , fl . , 



' =22/-184G cubic inches, 



(1+ T I T) X 18) 1-0375 

 which is equal to a decrease of 8*5194 cubic inches or 3*614 per cent. ; 

 then 225 — 227*1846 cubic inches gives 27*8154 cubic inches per minute, 

 or 1668*924 cubic inches per hour, or 40054*176 cubic inches per day= 

 10*907 per cent, as the grand total difference in favour of a temperate 

 climate, after deducting the real decrease in volume, and correcting for ex- 

 pansion by heat. By again reducing the 9*243 oz. of carbon by 3*614 

 per cent., or 0*33409 oz., we get 8*909 oz. as the total amount which the 

 lungs throw off in the tropics, the difference between the tropical and 

 extra-tropical quantities being 1*1028 oz. This result in the human 

 species accords with Vierordt's observation on the lower animals, viz. 

 that less carbonic acid and presumably less water are eliminated when 

 they are subjected to heat*. This, then, is probably the rule, but in ex- 

 ceptional cases, from idiosyncrasy, accelerated or forced respiration may 

 make the quantity of carbon which the lungs can exhale in temperate and 

 tropical regions more nearly alike. 



Thus the relative proportions of carbon thrown off by the several depu- 

 rating organs in the tropics differs from those of temperate latitudes. 

 Hooper f gives the latter as : — lungs 10J oz., skin \ oz., faeces J oz., urine 

 \ oz., total 1 1| oz. ; we have found that in the tropics the amount eliminated 

 by the lungs is reduced by 1^ oz. Under judicious hygienic, and especially 

 dietetic management, that for the skin, liver, and urine may not be 

 materially altered from these figures ; but otherwise it is probably on the 

 skin that the greatest share of its burden is thrown. We may presume 

 that the liver-work and bile are increased, though perhaps only slightly, 

 in the tropics, although this has not yet .been actually proved. The 

 kidneys may assist to a greater extent ; for though the urine is diminished 

 in quantity in the tropics, the relative amount of solids is not correspond- 

 ingly altered. Much of the latter may be carbon ; for though the urea 

 eliminated by the kidneys in the tropics is diminished +, the quantity of 

 uric acid, which contains thrice the amount of carbon, has not yet been 

 ascertained. 



The mutual bearing of these two closely related but very opposite re- 

 sults, viz. an increase in the capacity of the chest for air in the tropics, 

 with a decrease in the number of the respirations, is an interesting if not 

 important study. Hasty inference might lead us to attempt to explain the 

 former by a greater volume of the rarefied and moisture-laden air of the 

 tropics being required to supply the system with the requisite quantity of 

 oxygen. But there are several objections to this theory, e. g. : — 



1 . Nature might do this in health as she often does in disease, such as 

 phthisis, pneumonia, &c, by increasing the frequency of the respirations, 



* Parkes, ' Practical Hygiene,' 2nd edit. 



t Physicians' Vade Mecuni. 



% Parkes, ' Practical Hygiene,' 2nd edit. p. 448. 



