PEOFESSOR H. B. DIXON OX THE RATE OF EXPLOSION IN GASES. 103 
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. —Eepetition op Bepthelot’s Experiments. 
§ 1. Objects in View. 
A consideration of Berthelot’s results, published in the ‘ Annales de Chimie ’ * 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 obtamed 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 pre¬ 
pared in a graduated 5-feet iron gas-holder over water ; the mixtures containing 
ethylene, acetylene, cyanogen, and nitrous oxide were prepared in a l-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. Ckim. et Phys.,’ [V.] vol. 28 ; also ‘ Snr la force des Matieres Explosives,’ vol. 1., cbap. 7. 
