1893.] 



On the Densities of the Principal Gases. 



145 



Air drawn through solution of potash was deprived of its oxygen 

 by reduced copper, contained in a tube of hard glass heated by a 

 large flame. It then traversed a U _ ^ 11 ^ e J i n which was deposited 

 most of the water of combustion. The gas, practically free, as the 

 event proved, from oxygen, was passed, as a further precaution, over 

 a length of copper heated in a combustion furnace, then through 

 strong sulphuric acid,* and afterwards back through the furnace over 

 a length of oxide of copper. It then passed on to the regulating tap, 

 and thence through the remainder of the apparatus, as already de- 

 scribed. In no case did the copper in the furnace, even at the end 

 where the gas entered, show any sign of losing its metallic appearance. 



Three results, obtained in August, 1892, were — 



August 8 2-31035 



„ 10 2-31026 



„ 15 2-31024 



Mean 2'31028 



To these may be added the results of two special experiments made 

 to test the removal of hydrogen by the copper oxide. For this pur- 

 pose a small hydrogen generator, which could be set in action by 

 closing an external contact, was included between the two tubes of 

 reduced copper, the gas being caused to bubble through the electro- 

 lytic liquid. The quantity of hydrogen liberated was calculated 

 from the deflection of a galvanometer included in the circuit, and 

 was sufficient, if retained, to alter the density very materially. Care 

 was taken that the small stream of hydrogen should be uniform 

 during the whole time (about 2J hours) occupied by the filling, but, 

 as will be seen, the impurity was effectually removed by the copper 

 oxide. f Two experiments gave — 



September 17 2-31012 



20 2-31027 



Mean 2-31020 



We may take as the number for nitrogen — 



2-31026 



Correction for contraction. . 56 



2-31082 



* There was no need for this, but the acid was in position for another purpose. 



f Much larger quantities of hydrogen, sufficient to reduce the oxide over several 

 centimetres, have been introduced without appreciably altering the weight of the 

 gas. 



VOL. LIII. L 



