4 Thomson, Atmospheric Pressure on Anvnal Metabolisvi. 



pared with determinations made by passing measured 

 volumes of air through a Stromeyer coil absorption tube 

 containing strong sulphuric acid and weighing the moisture 

 so absorbed. 



The humidity determinations can therefore onl\' be 

 regarded as roughly and approximately correct. 



The following figures and the diagrams shew the 

 results obtained from the exlialed air from four persons 

 breathing town air. 



It was found that under normal conditions an average 

 greater metabolism takes place in one person than another. 

 Thus the following persons are those whose exhaled air 

 was analysed in the series of experiments to be put before 

 you, and the following figures shew the ranges of CO^ 

 contained in them : — 



CO._. coni.aineil in 



exhaleil air in Town. 



Per cent. 



Dr. W., age 38 37 to 42 



J. W. ,,22 5 '4 to 62 



N. T. F. „ 21 3-6 to 43 



B. S. ,,15 4-2 to 5-3 



These figures were obtained in my Laboratory in 

 Manchester. It was found, however, in previous experi- 

 ments that exhaled air containing about 4 per cent, in town 

 rose to about 5 |)cr cent, of CO.^ when breathing uncontami- 

 nated air in the country, siicwing an increase of about 25 

 per cent, when tho samples were taken in bottles as above 

 described. 



Ill the final series of experiments (sec Table at end) 

 the determinations were made by the gas-holder arrange- 

 ment between 9 and lo in the morning and between 

 2 and 3 in the afternoon of each da)-. It was fountl that 

 in the afternoon the average results were somewhat 

 higher than in the morning. 



