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SCIENCE PROGRESS 



the bottle D. The whole apparatus being still full of hydrogen, 

 the taps b and d were closed, c was opened and the portion 

 of the apparatus above tap b was exhausted by means of the air 

 pump. The taps c and a were now closed, b was opened and 

 water was distilled into the T-piece above tap a until the level 

 of the distilled water reached tap c. On opening the tap c the 

 water, saturated with pure hydrogen, entered the tube A and 

 completely covered the piece of iron. The tap b was now 

 closed and the portion of the apparatus above it filled with 

 pure oxygen admitted through tap d. " The utmost care 

 was taken that this oxygen was completely free from carbon 

 dioxide by passing it through three wash bottles containing 



Ibpump. 



Fig. i. 



aqueous potassium hydroxide and afterwards through a tower 

 of solid potassium hydroxide." It was found that as long as the 

 iron was left in contact with the water saturated with hydrogen 

 and in an atmosphere of the same gas, no action occurred. 

 Directly oxygen was admitted, however " action immediately 

 commenced" and in a short time rust became visible. 



Sufficient as the precautions adopted might appear for the 

 purpose of excluding carbon dioxide, their inadequacy has 

 been clearly demonstrated by the results obtained by Dr. 

 G. T. Moody and published in the Transactions of the Chemical 

 Society for April 1906. These results established beyond doubt 

 that when very special precautions are taken to eliminate 

 carbon dioxide, iron may be left in contact with purified oxygen 

 and water for many weeks without undergoing change. In 

 discussing the foregoing results, Dr. Moody points out that 



