174 Prof. Thomson, On the Existence of a Radio-active Gas, etc. 



new lines were however discovered, the lines present being mainly 

 those due to hydrocarbons. 



I add a list of the various specimens of water I have examined ; 

 'yes' means that the water contains the gas, 'no' that it does not. 



Cambridge tap-water (yes). Rain water (no). Water from 

 ditch round Botanical Garden (no). Water from Trinity College 

 well on the Madingley Road (yes). Water from artesian well in 

 Mr Whetham's garden, Chaucer Road (yes). Water from shallow 

 well in same garden (no). Water from well at Star Brewery (yes). 

 Artesian well in Trinity Hall Cricket Ground (yes). Artesian 

 well at Girton (yes). Ely Town's water (yes). Birmingham 

 Town's water (yes). Ipswich Town's water (yes). 



In concluding this preliminary account I have much pleasure 

 in thanking my assistant, Mr E. Everett, for his help in this 

 investigation. 



