538 ADVENTURES IN RADIOISOTOPE RESEARCH 



body by an independent method. The result works out again as 9 J^ 1 

 days. By dividing the last figure by In 2, we get for the average time 

 a water molecule spends in the body 13 zh 1-5 days. To explain this 

 comparatively long time, we have to assume that most of the water 

 taken becomes completely mixed with the water content of the body. 

 This assumption can be tested by calculating the water content of the 

 body of the experimenter from thea mount of diluted heavy water taken, 

 and the density of the water prepared from urine any day except the 

 first one. We arrive at a water content of 43 ± 3 litres, namely, 63 i 4 

 per cent in fair accordance with known data. 



References 



1. H. J. Emeleus, F. W. James, A. King, T. G. Pearson, R. H. Purcell and 

 H. V. A. Briscoe, J. Chem. Soc. 1204 (1934). 



2. G. v. Hevesy and E. Hofer, Hoppe-Seyler Z. 225, 28 (1934); cf. G. N. Lewis, 

 Science 19, 151 (1934); H. E. Erlenmeyer and H. Gartner, Helv. chim. Acta 

 17, 334 (1934). 



