THE VITAL FUNCTIONS. 865 



time, it produces opposite and deleterious effects, 

 changing the blood from its previous florid colour 

 to a dark hue, as shewn by the purple colour of 

 the face, for it has been observed by Sir H. 

 Davy and others, that after being breathed for 

 some time, the greater part of its oxygen disap- 

 pears, the residue, consisting chiefly of nitrogen 

 and carbonic acid, a portion of which is absorbed 

 into the blood, causing confusion of the brain, and 

 sometimes syncope, with more or less derange- 

 ment of all the vital functions. 



It has been said, that when taken into the lungs 

 in moderation, after exhaustion from over exer- 

 tion, it removes at once the sensation of weak- 

 ness and fatigue, without being followed by that 

 debility which succeeds over excitement from 

 ordinary stimulants. There is, therefore, reason 

 to hope that when its modus opemndi in exalting 

 the powers of life shall be better understood, it 

 will be found highly important as a therapeu- 

 tical agent in cases of torpor of the stomach, 

 bowels, liver, and brain, which characterize dys- 

 pepsia, hypochondriasis, hysteria, chlorosis, and 

 the cold stage of all fevers, especially in con- 

 junction with the warm bath, moderate exercise, 

 regimen, &c. 



The quantity of respiration is greatly diminished 

 in a rarefied atmosphere, as on the tops of high 

 mountains. The consequences of which are, hur- 

 ried and difficult breathing, small and frequent 



