Letter from Frederick Soddy, FRS, Chemical Laboratory, Glasgow University, to James Mackenzie Davidson Urges Mackenzie Davidson to send him word if his radium will be of use. Explains that it is easy enough to get the induced activity of thorium in acqueous solution by making the water negative with aspect to the walls of the bottle and blowing the emanation through. Offers advice on how to make the water negative and encloses an illustration of the apparatus necessary [enclosed, see MS/929/1/188a]. 10 March 1905