IN GASES: HYDROGEN, CARBONIC OXIDE, AND OXYGEN. 
639 
On allowing the pendulum to fall the style registered a mark on the moving plate 
when the circuit was broken. Without moving the chronograph the wires were 
readjusted, and the explosion made. The distance between the two marks on the 
blackened plate gave the time which elapsed between the breaking of the primary coil 
of the Buhmkorff and the rupture of the silver foil by the explosion, independently 
of the error of the chronograph ; for the position of both marks was affected 
equally by the retardation of the electro-magnet. The rate of the pendulum, and 
therefore the interval of time corresponding to the two marks, was determined by 
taking the trace of a standard tuning fork on the blackened plate allowed to fall from 
the same height. By filling the trough with water and heating it with two argand 
burners, the explosion tube could be kept at any desired temperature. 
Three sets of experiments were made, one at 10° C., the second at 35° C., and the 
third at 60° C. The mixture of gases, containing two volumes of carbonic oxide to one 
volume of oxygen, was contained in a copper holder over water. After the explosion tube 
had been dried by heating and drawing through it for some hours air which had passed 
through three long tubes containing pumice saturated with oil of vitriol, the mixture 
of carbonic oxide and oxygen was driven slowly into the tube, (1) through two 
sulphuric acid drying tubes, and (2) through two long tubes containing anhydrous 
phosphoric acid. When two or three litres of the mixture had been driven through 
the tube, the stopcocks at both ends were closed and the mixture fired at a tempera¬ 
ture of 10° and under the atmospheric pressure. The interval between the spark and 
the rupture of the silver foil was found to be '0291 second, giving a mean velocity of 
36 metres per second. The tube was then heated to 35° by means of warm water in 
the trough, and some more of the same mixture was driven in through the same 
drying tubes. The gases fired at 35° had a mean velocity of explosion of 69 metres 
per second. On recharging the drying tubes with fresh phosphoric acid and. repeat¬ 
ing the experiment at 35° the mean velocity of explosion was found to be 44 metres 
per second. With the same drying tubes as in the last experiment the mean velocity 
at 60° was found to be 53 metres per second. 
When the mixture was made to bubble through two sulphuric acid wash-bottles 
only, a far higher velocity was obtained. At 10° C. the mean velocity was found to be 
119 metres, at 35° C. 103 metres and 102 metres, and at 60° C. 120 metres per second. 
When the mixture was exploded at 10° C. and saturated with steam at that 
temperature a mean velocity of 175 metres was reached. At 10°C., therefore, the 
velocity of explosion of carbonic oxide and oxygen under atmospheric pressure is 
greatest when it is saturated with steam. At 35° C. a similar result was found. 
In three successive experiments the mixture was driven into the warm tube through 
a wash-bottle containing water at 6°, 8°, and 12° C. respectively. The velocity of 
explosion increased with the quantity of steam present. When saturated with steam 
at 35° C. the mixture gave a velocity of 225 metres per second. When the tube was 
heated to 60° C., and the mixture driven in over water at different temperatures, the 
