EXHALATION OF CARBON DIOXIDE 125 



of vapor exhaled, in the number of respirations and in the rapidity of 

 the pulse. The exhalation of carbon dioxide was diminished by one- 

 fourth. An important point in this observation was that the quantity 

 was as small four and a half hours after eating as at the end of the 

 twenty-seven hours. 



Influence of Diet. The most extended series of investigations on 

 the influence of diet upon the absolute quantity of carbon dioxide ex- 

 haled are those of Edward Smith. This observer made a large number 

 of experiments on the influence of various kinds of food and extended 

 his inquiries into the influence of certain beverages, such as tea, coffee, 

 cocoa, malt liquors and fermented liquors. He divided food into two 

 classes : one which increased the exhalation of carbon dioxide, which 

 he called respiratory excitants, and the. other, which diminished the 

 exhalation, he called non-exciters. The following are the results of a 

 large number of observations upon four persons : 



"The excito-respiratory are nitrogenous food, milk and its compo- 

 nents, sugars, rum, beer, stout, the cereals, and potato. 



" The non-exciters are starch, fat, certain alcoholic compounds, 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 chiccory ; then casein and gluten, 

 and lastly, gelatin and albumen. The amount of action was not in uni- 

 form proportion to their quantity. Compound ailments, 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, while others, as sugar, supply more than they evolve in 

 this excess, that is, above the basis. No substance containing a large 

 amount of carbon 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 experiments." 



The comparative observations on the four subjects of experiment 

 demonstrated one important fact ; namely, that the action of different 

 kinds of food on respiration is modified by idiosyncrasies and the tastes 

 of different individuals. 



The following are the results of observations on the effects of differ- 

 ent alcoholic beverages taken during the intervals of digestion : 



" Brandy, whiskey, and gin, and particularly the latter, almost always 



