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SCIENCE PROGRESS 



until a vacuum is produced. The emanation is not present in 

 sufficient quantity to admit of its being pumped away by itself. 

 But both radium salts and emanation decompose water, the 

 property being probably due to the action of a rays. Hydrogen 

 and oxygen are produced in comparatively large quantity. Sir 

 William Ramsay found that as a mean of eight experiments 

 varying from 48 to 336 hours, 32 cubic centimetres of the mixed 

 gases are produced by 1 gram of radium bromide in 100 hours. 



TO PUMP 



Fig. 1. 



The quantity from 50 milligrams, v6 c.c, can quite easily be 

 passed through the pump without loss. This is the gas which 

 is actually collected in the test-tube ; the emanation is carried 

 along with it. There may also be present a very small trace 

 of carbon dioxide. 



There is one remarkable feature about the proportions of 

 hydrogen and oxygen in the mixed gases. They never exactly 

 correspond to those required for the formation of water; there 

 is always some 3 to 10 per cent, of excess hydrogen. This excess 

 has not yet been explained completely. Part, perhaps the 

 whole, may be due to the formation of hydrogen peroxide in 



