436 RESPIRATION. 



pounds, the volatile elements of wines and spirits, and coffee 

 leaves. 



" Respiratory excitants have a temporary action ; but the 

 action of most of them commences very quickly, and attains 

 its maximum within one hour. 



" The most powerful respiratory excitants are tea and 

 sugar ; then coffee, rum, milk, cocoa, ales, and chicory ; then 

 casein and gluten, and lastly, gelatin and albumen. The 

 amount of action was not in uniform proportion to their 

 quantity. Compound aliments, as the cereals, containing 

 several of these substances, have an action greater than that 

 of any of their elements. 



"Most respiratory excitants, as tea, coffee, gluten, and 

 casein, cause an increase in the evolution of carbon greater 

 than the quantity which they supply, whilst others, as sugar, 

 supply more than they evolve in this excess, that is, above 

 the basis. ~No substance containing a large amount of car- 

 bon evolves more than a small portion of that carbon in the 

 temporary action occurring above the basis line, and hence 

 a large portion remains unaccounted for by these experi- 

 ments." 



The comparative observations of Dr. Smith upon the four 

 persons who were the subjects of experiment demonstrated 

 one very important fact : namely, that the action of different 

 kinds of food upon respiration is modified by idiosyncrasies, 

 and the tastes of different individuals. For example, in ex- 

 periments on his own person, certain articles which were 

 agreeable to him excited the exhalation of carbonic acid ; but 

 in experimenting with the same articles upon Mr. Choul, to 

 whom they were distasteful, he found the respiratory action 

 diminished. 



Quite a number of observers have noted the influence of 

 alcohol upon the products of respiration ; but the results of 

 experiments have not been entirely uniform. Prout ob- 

 served a constant diminution in the quantity of carbonic acid 

 exhaled, under the influence of alcohol. This has been confirm 



