ijluence of Si 



329 



the fact that on that day I failed in an experiment for determin- 

 ing the dew-point by means of Daniell's hygrometer.^ 



From the foregoing discussion it is evident that the subject de- 

 mands a thorough experimental investigation, with a minute at- 



* Collaterally related to this subject are the effects of condensed and rarefied air 

 and of temperature on the process of respiration and the elimination of carbonic 

 acid In men and other warm blooded animals. M. Legallois found tliat ^vhen warm- 

 blooded animals breathed air under pressure reduced to 11-811 iuches, the amount 

 of oxj^gen consumed was diminished. (Ana. de Chemie et de Phys., tome 4, p. 113, 

 1817.) M. Theodore Junod's experiments show that coiidensed air produced deep 

 inspirations and an agreeable glow throughout the system; while rarejied air had 

 an opposite effect, (Archives Generales de Medecine, 2d series, tome 9, p. 157. 

 Paris, 1835. Also, Magendie's Report on the same Memoir, Comptes Eendus, tome 

 1, p. GO. Paris, 1835.) The observations of M. Triger, already referred to, indicate 

 analogous effects on those who labored in the condensed air. They could do doable 

 work without fatigue, and even old asthmatics seeined to recover their vigor. 

 (Comptes Rendus. tome 13, p. 884, et seq. Paris, 1841.) M. Vierordt tested the 

 effects of barometric pressure between 29309 and 30197 inches. The average rise 

 of 0-5036 of an inch, 



Increased the air expired 35''746 cub. inches per minute. 



" No. of respirations 0"Y4 " 

 « " " pulse 1-30 " 



pr. Hutchinson found that in a mine 1488 feet deep, where the pressure was 1*54 

 inches more than at the sea-level, the respiration was increased 2-4 per minute, and 

 the pulse 1*3 per minute.(Cyc. of Anat. et Physiol, farticle Respirationl vol 4, p. 

 348-349. Lona.,185^.) i J > k' 



Analogous effects are produced by temperature, la the famous experiments of 

 S^guin and Lavoisier, at 82° Fahr., the former (fasting and at rest) consumed 1210 

 French cubic inchcj^ of oxygen per hour; whereas at 57^, he consumed 1344 cubic 

 iiicbes per hour. {Memoires de I'Acad. Royale, for 1789.) Dr. Crawford found, that 

 a Guinea pig at 55'^"5 F. abstracted twice as much oxygen from the air as at 104° F. 

 (Sxpts and Obs. on Animal Heat, 2d ed., p. 311-315. Lend., 1788.) Dr. W. F. Ed- 

 wards found that birds consume more oxygen in winter than in summer, (De I'ln- 

 fluence des Agens Physiques sur la Vie," chap. 6, p. 195. Paris, 1824.) Tlie best 

 t'xpt^riments are those of M. Vierordt, {^Op. cit, supra) He obtained the following 

 results between 37^*4 and 75^-2 Falir. 



u 



u 



(( 



(« 



M 



<l 



Pulse per minute, 



Respiration per minute, 



Vol of Air exp'd per minute in cub. inches, 



Av. Teinp 

 47°-24 . 



72*93 

 1216 



40700 

 18-25 



Av. Temp 

 66** -9^ 



Diff. 





71-29 



11-57 



36700 



15-72 



1-64 



0-69 



4000 



2-53 



M. Felix Letellier's experiments on warm-blooded animals confirm these results. 

 He found the amount of carbonic acid evolved j?er hour at different temperatui'es, to 

 be as follows : 





Canary, 

 -f "geon, 

 Two Mice, 

 C^uinea Pig, 



86'' to 104.'' F. 



br to 68^ F. 



0'129 



grammes. 



0-36G 





0-268 



« 



1-453 



« 



0*250 grammes, 



0684 



0-498 



2 080 " 



32^ P. 



325 grammes. 



0-974 

 0-531 



«'006 « 



(t 



(( 



{Vid^ Comptes Rendus, tome 20, p. '795. Paris, 1845. Also, Ann. de Cheniie et 

 ae Phjs., 3d series, tome 13. p. 478. Paris, 1845.) Doubtless physiological reac- 

 ^ions exercise a powerful influence over the results of such experinienta ; nererthe- 

 le:^^, as respiration is essentially a process of combustion, they have a geiural bearing 

 on the question under consideration, 



SECOND SERIES, VOL. XXIV, NO. 73.— NOV., 1837. 



42 



