170 PROFESSOR H. B. DIXON ON THE RATE OF EXPLOSION IN GASES. 
“firing piece/’ the other end to a shorter tube, called the “ end piece,” carrying the 
second “ bridge.” 
Fig. 2. 
Section of drum mounted on turntable, and trolley for winding the explosion tube. 
The caps which carried the bridges to be broken by the flame were constructed in 
the followinof wav :— 
The steel tube AA was pierced at a distance of 30 mm. from the face by two 
conical holes opposite each other. The interior of the tube was lined wdth a cylinder 
of vulcanite, which also filled the conical holes. Two thick platinum v.dres, DD, 
passed through the holes, and were soldered to two pieces of silver, CC, embedded in 
the vulcanite, and thus insulated from the steel tube. The silver pieces were 
broadened out at the face end into two small plates, on to which the narrow strip of 
silver foil forming the bridge was soldered. The silver j^lates were brought not quite 
flush with the polished steel face, so that there was no danger of breaking the bridge 
when clamping up the two caps. 
Fig. 
3. 
Fig. 4. 
For the experiments with chlorine and hydrogen a glass tube was fixed inside the 
vulcanite so as to protect it from the action of the chlorine. The silver bridge, alter 
being soldered to the silver plates, was warmed and coated wdth a layer of paraffin as 
a protection from the chlorine. 
