Prof. Dcebcreiners recent Discovery , to Endiomelry . 103 
explosion when one volume of hydrogen was mixed with four of 
oxygen, nor when one of oxygen was added to four of hydro- 
gen. Atmospheric air and hydrogen may be mixed in any pro- 
portion without danger of explosion. 
The ball itself suffers no chemical change ; at least I have 
used the same one in fifty different experiments, without obser- 
ving the least diminution of its energy. Its activity does indeed 
diminish after repeated use, if not ignited during the experi- 
ments, but is completely restored by heating the ball to redness. 
The method I pursued in all the succeeding experiments, was 
to throw the flame of an oil or spirit lamp upon the ball, by 
means of a blowpipe, so as to keep it intensely hot for the space 
of one minute, after which it was allowed to sink to the tempe- 
rature of the room before being used. Sometimes, however, it 
was necessary to plunge the ball through mercury while strong- 
ly heated, and this occasionally destroyed its action most com- 
pletely ; though its energy was restored by keeping it for a few 
minutes in the strongest heat of the blowpipe. I have some- 
times observed the energy of an active ball so completely de- 
stroyed by passing it through mercury, that it did not produce 
the slightest effect in a highly explosive mixture. 
Eleven volumes of atmospheric air were mixed with one vo- 
lume of hydrogen. An electric spark was passed through one 
portion of the mixture, and the ball No. 3. brought in contact 
with another. Detonation occurred in the first case, and in the 
second, diminution of the volume of gas, with deposition of wa- 
ter. A strong charge of electricity was passed through a mix- 
ture, composed of 13 air to 1 hydrogen, without any detona- 
tion ; whereas the balls, Nos. 3. and 5., afterwards caused im- 
mediate diminution. Repeated strong charges from a Leyden 
jar were sent through a mixture of 15 air to 1 hydrogen, with- 
out any detonation, while balls Nos. 3. and 5. acted instantly. 
A mixture, composed of 19 air to 1 hydrogen, was not at all 
influenced by electricity ; but balls Nos. 3. and 7. caused for- 
mation of water, as did No. 8. when warm. The ball No. 3. 
was put into a mixture, composed of 1 volume of hydrogen to 
4 of air : an abundant deposition of water followed ; and in one 
minute after the entrance of the ball, the residual gas was trans- 
ferred into a eudiometer and electrified, but without any deto- 
