A NEW CONSTITUENT OF THE ATMOSPHERE. 241 
flask was coupled with a tube full of red-hot copper oxide, intended to oxidise the 
hydrogen which would be evolved by the action of the hydrochloric acid on the 
metallic magnesium. To the end of the copper-oxide tube a gas-holder was attached, 
so as to collect any evolved gas; and the system was attached to a vacuum-pump, in 
order to exhaust the apparatus before commencing the experiment, as well as to 
collect all gas which should be evolved, and remain in the flask. 
On admitting hydrochloric acid to the flask of magnesium nitride a violent 
reaction took place, and fumes of ammonium chloride passed into the tube of copper 
oxide. These gave, of course, free nitrogen. This had not been foreseen ; it would 
have been well to retain these fumes by plugs of glass-wool, The result of the 
experiment was that about 200 cub. centims. of gas were collected. After sparking 
with oxygen in presence of caustic soda, the volume was reduced to 3 cub. centims. 
of a gas which appeared to be argon. 
MDCCCXCV,—A, 2) 
