248 ANNUAL OF SCIENTIFIC DISCOVERY. 



quantity increased after a meal and decreased from each meal, so that the 

 minima were nearly the same, and the maxima were the greatest after 

 breakfast and tea. 



The effect of a fast of forty hours, with only a breakfast meal, was to 

 reduce the amount of carbonic acid to seventy-five per cent of that which 

 was found with food, to render the quantity nearly uniform throughout the 

 day, Avith a little increase at the hours when food had usually been taken, and 

 to cause the secretions to become alkaline. 1 



The variations from day to day were shown to be connected with the 

 relation of waste and supply on the previous day and night; so that, with 

 good health, good night's rest, and sufficient food, tho amount of respiration 

 was considerable on the following morning, whilst the reverse occurred wirii 

 the contrary conditions. Hence the quantities were unusually large on Mon- 

 day. Temperature was an ever-acting cause of variation, and caused a 

 diminution in the carbonic acid as the temperature rose. 



The effect of season was to cause a diminution of all the respiratory phe- 

 nomena as the hot season advanced. The maximum state was in spring, and 

 the minimum at the end of summer, with periods of decrease in June and of 

 increase in October. The diminution in the author was thirty per cent in the 

 quantity of air, thirty-two per cent in the rate of respiration, and seventeen 

 per cent in the carbonic acid. The influence of temperature was considered 

 in relation to season, and it was shown that whilst sudden changes of temper- 

 am re cause immediate variation in the quantity of carbonic acid, a medium 

 degree of temperature, as of GCP, is accompanied by all the variations in 

 the quantity of carbonic acid, and that there is no relation between any given 

 temperature and quantity of carbonic acid at different seasons. Whatever 

 was the degree of temperature, the quantity of carbonic acid, and all other 

 phenomena of respiration, fell from the beginning of June to the beginning 

 of September. The author then described the influence of atmospheric pres- 

 sure, and stated that neither temperature nor atmospheric pressure accounts 

 for the seasonal changes. 



The kinds of exenion which had been investigated were walking and the 

 tread wheel. Walking at two miles per hour induced an exhalation of 18.1 

 grains of carbonic acid per minute, and at three miles per hour, of 2-3.83 

 grains; whilst the effect of the treadwheel, at Coldbath Fields Prison, was to 

 increase the quantity to 48 grains per minute. All these quantities vary 

 with the season; and hence the author recommends the adoption of relative 

 quantities, the comparison being with the state of the system at rest, and 

 apart from the influence of food. 



APPLICATION OF THE PHYSICAL SCIENCES TO MEDICINE. 



A discussion which has recently taken place in the French Academy of 

 Medicine, on the action of iron used as a medicine, has made known to us this 

 unexpected fact, that there are physicians who deny any influence exercised 

 by medicines in virtue of their chemical properties, and who think that the 

 physical and chemical actions of the animal economy differ entirely from 

 those which are observed in the vegetable kingdom, 



l The quantity of air was reduced thirty per cent, that of vapor in the expired 

 air fifty per cent, the rate of respiration was reduced seven per cent, and of 

 pulsation six per cent. 



