obtainable with any mixture of gases, but it also affords us information on the specific heats of gases at very high temperatures, and it explains the phenomena of detonation whether of gases or of solid or liquid explosives.
CAP. III.—REPETITION OF BERTHELOT'S EXPERIMENTS.
§ 1. Objects in View.
A consideration of Berthelot's results, published in the 'Annales de Chimie'[1] in 1883, led me to think it would be useful to repeat and extend these experiments. The close coincidence between the rates of explosion of hydrogen, both with oxygen and with nitrous oxide, and the calculated velocities of the products of combustion showed that the formula held good for gases which could readily be prepared in a pure state; and, again, the great discordance between the found and calculated rates for carbonic oxide, both with oxygen and nitrous oxide, was what I should have expected from my own experiments on the part taken by steam in the oxidation of carbonic oxide. On the other hand, Berthelot's contention that the gases are heated at constant pressure appeared improbable, and his results obtained with the addition of an inert gas seemed to vary capriciously. The chief objects I had in view in continuing these experiments were:—
(1) To determine as accurately as possible the rate of the explosion-wave for some simple mixtures under varying conditions, e.g., diameter of tube, initial pressure, initial temperature.
(2) To measure the rate of the explosion-wave in carbonic oxide and oxygen with different quantities of steam.
(3) To compare the effect of inert gases and of excess of one or other of the reacting gases on the rate of explosion.
$ 2. Methods and Apparatus used.
The mixtures of hydrogen, carbonic oxide, and marsh gas with oxygen were prepared in a graduated 5-feet iron gas-holder over water ; the mixtures containing ethylene, acetylene, cyanogen, and nitrous oxide were prepared in a 1-foot iron holder over mercury; the mixtures of hydrogen and chlorine were passed directly from the generating and purifying apparatus into the explosion tube.
The gases were driven from the holders through drying vessels into the explosion tube by placing weights upon the holders. When all air-traps were avoided in the drying tubes and connections, very little diffusion was found to occur in driving out the air by the explosive mixture. One "Drechsel" washing bottle and three towers packed with pumice, all containing boiled oil of vitriol, were usually employed as drying vessels. When the explosive mixture contained either ethylene or acetylene
- ↑ 'Ann. Chim. et Phys.,' [V.] vol. 28; also 'Sur la force des Matières Explosives,' vol. 1., chap. 7.
