IN' GASES: HYDROGEN, CARBONIC OXIDE, AND OXYGEN. 
631 
succession of sparks was passed, but the platinum wires became red hot, showing that 
some local action was produced. Under 250 millims. pressure the gases ignited on 
passing the spark. The disc of flame took about three seconds to travel down the 
half-metre of tube filled with the mixture. Some of the same mixture, standing in 
the laboratory tube, was charged with aqueous vapour by passing a drop of water to the 
surface of the mercury. It was drawn over into the vacuous eudiometer and put under 
150 millims. pressure. On passing a spark from the coil the gases exploded suddenly 
down the tube. The passage of the flame was too quick to be followed by the eye. 
Into a small straight eudiometer, heated and filled while hot with hot mercury, 
some of the same gaseous mixture was passed up. A little phosphoric oxide [powder] 
was then introduced into the tube, which was shaken so that the oxide adhered to 
the sides of the glass. The gases were left standing in the tube for an hour. A spark 
from a Ley den-jar was then passed between the platinum wires without effecting the 
ignition of the gases. The gases were under a pressure of 700 millims. Several powerful 
sparks were passed without any result. A discharge from the coil ignited the gases. 
This experiment was repeated with the following modifications. Into the gaseous 
mixture in the small eudiometer was passed up a stick of phosphoric oxide, made by 
pressing the powder into a short glass tube closed at one end with a cork. To pass up 
this stick, the glass tube was depressed under the end of the eudiometer, the cork 
removed, and the phosphoric oxide pushed up by a glass rod. The gases were allowed 
to stand for two days in contact with the phosphoric oxide, the eudiometer being 
clamped down on to a caoutchouc cushion under mercury. On passing a spark from 
a Leyden-jar, no combustion took place. The pressure was 700 millims. The first 
discharge from the coil caused a very slight combustion near the wires. On loosening 
the clamp the mercury rose about 2 millims. in the tube. No further combination took 
place on passing a succession of sparks from the coil. A little water was then 
introduced by a pipette. The heat evolved on contact of the oxide with the water 
caused the mixture to explode with a bright and sudden flash. 
It appears from these experiments that the greater the degree of dryness reached, 
the greater pressure the gases can withstand without entering into explosive com¬ 
bination when an electric spark is passed through them. 
An attempt was next made to dry the gases and tubes more thoroughly. A 
mixture of the two gases in the same proportions, and prepared in the same way, was 
placed in a glass gasholder over concentrated sulphuric acid. The explosion tubes, 
each drawn out at one end, and fitted at the other with a caoutchouc stopper and glass 
tube, were joined together by short pieces of india-rubber tubing. They were then 
strongly heated, while air, previously dried by passing through a horizontal sulphuric 
acid tube, was aspirated through them. When cool, the stopper of each was removed, 
a plug of freshly-packed phosphoric oxide quickly pushed in, and the stopper immediately 
replaced. The tubes were then drawn out near the stoppered end in the blow-pipe 
flame. They were then reconnected by short pieces of tubing. Between the gasholder 
