254 Dr. W. Marcet and Mr. R. B. Floris. An Experimental 



in the calorimeter unaccounted for. Some C0 2 must be derived from 

 the skin, and perhaps some small quantity of air might possibly have 

 escaped from the face-piece into the chamber. 



The calorimeter was conveniently available for the determination 

 of the C0 2 , which might have collected in it, as the chamber was 

 perfectly closed, whatever minute openings there were being much 

 too small to allow of any diffusion out of the chamber. This was 

 tested experimentally in the course of the present enquiry by 

 expiring air into the bell-jars, while out of the .calorimeter ; shortly 

 afterwards the same person entered the chamber and breathed in 

 it for forty minutes or an hour. The mean of eight experiments 

 gave figures for the C0 2 in and out of the chamber exactly the 

 same.* 



The determination of the C0 2 in the air of the chamber while 

 breathing the external air was made by putting on the face-piece 

 on entering the calorimeter, and after the door was closed, rinsing a 

 dry flask (holding about 6 litres) with air from the upper agitator ; 

 this flask was then stopped with an india-rubber cork, having a tube 

 with a stopcock inserted through it. After sixty minutes another 

 large, dry flask, full of fine, dry sand, was suddenly emptied of its con- 

 tents, and closed with a cork similar to that used with the other 

 flask. The determination of C0 2 was made in each flask with a 

 standard solution of barium hydrate, by Pettenkofer's method. The 

 C0 2 in the chamber was obtained by subtracting the weight (or 

 volume) of C0 2 found in the chamber at the very beginning of the 

 experiment from the weight of the C0 2 found in the chamber after 

 the subject had remained an hour in it. This C0 2 varied somewhat 

 with the three persons who submitted to experiment ; the mean 

 value for each of us was used for the correction of the oxygen ab- 

 sorbed ; this correction was, however, but small, varying from about 

 1 to 3 per cent, of the CO 2 determined in the air collected in the 

 bell -jar. 



The results obtained from the present enquiry may be summarised 

 as follows : 



1. The amount of heat given out from the human body when 



194-8 



194-7 



