262 



Professor Sir James Dewar 



[Jan. 2; 



As regards these Tables, it may be noted that all three give the 

 records of similar processes of analysis. In II. air is taken ; oxygen 

 is removed in the various ways indicated ; nitrogen is frozen out at 

 20° Abs., and the presence of minute quantities of rare gases and 

 hydrogen remaining uncondensed is measured. In I. the sources of 

 the gases were varied, and large changes in the quantity of uncon- 

 densable gases recorded. In III. several samples of lung gases were 

 examined, and the hydrogen and other gases differentiated, the volume 

 being found to be considerably greater than that in ordinary air, the 

 variation from the mean quantity of about twenty-three volumes per 

 million being due to the presence of hydrogen produced in the body. 

 The method of taking a sample of respired air is shown in Fig. 9. 



Fig. 9. 



The flask has a ground cone for direct attachment to the purifying 

 part of the apparatus employed, whereby the uncertainties introduced 

 by india-rubber connections are avoided. Such precautions are very 

 necessary where minute quantities of hydrogen, helium and neon are 

 being measured. [j. D.] 



Mr. W. J. Green, B.Sc, of the Dav}^ Faraday Laboratory, has given valuable 

 assistance in the conduct of the investigation ; and Mr. J. W. Heath, F.C.S., in 

 the Lecture Arrangements. 



