lOG PROFESSOR H. B. DIXOX OX THE RATE OF EXPLOSION IX GASES. 
a, The explosion tube was longer and wider. 
h. The interrupters or “ bridges ” were of silver foil, and no fulminate was used. 
c. A longer space was allowed between the firing spark and the first “ bridge ” 
where the record of the rate was begun. This was found essential in 
several cases, especially when the mixture was fired under reduced 
pressure, or in presence of inert gases, in which cases the explosion does 
not reach its maximum rate for some feet. 
§ 3. On the Constant Velocity of the Exyolosion Wave. 
Experiments on the rate of explosion of hydrogen and oxygen in a leaden tube, 
55 metres long and 8 mm. in internal diameter, gave a mean rate of 2817 metres 
per second. In a tube of the same diameter and 100 metres long, the mean rate was 
2821 metres; and in a tube 100 metres long and 13 mm. diameter the mean rate 
was 2819. 
The general mean of these experiments—-viz., 2819, is in close agreement with the 
mean result obtained by Berthelot in a shorter tube—viz., 2810. 
The constancy of the rate of the explosion-wave, under ordinary conditions of 
temperature and pressure, was, therefore, fully confirmed. 
In the course of this investigation I have made many measurements of the rate of 
explosion of hydrogen and oxygen under ordinary conditions. Some of these were 
made with more precautions than others, so that in ariiving at the most probable 
value of the rate, I have given greater weight to some sets than to others. The sets, 
each of which consists of from eight to ten distinct measurements, are lettered in the 
following table A, B, C, etc., in the order in which they were made :— 
Table V.—General Mean of Hg + C) Bates. 
Date. 
Sets. 
Mean. 
1884, 1885 
A -f B + C 
2819 
1888 
D 
2822 
1889 
E + F A G 
2824 
1890 
H 
2818 
2821 
The details of these experiments will be found in the Appendix. 
§ 4. The Infuence of Pressure on the Velocity of the Explosion Wave. 
Preliminary experiments on the rate of explosion of hydrogen and oxygen under 
500 mm. and 1000 mm. pressure having shown an appreciable difference, careful 
