of the two gases. The experiment was first tried with hydrogen
and common air, the oxygen of the air uniting with the hydrogen
to form water, leaving the nitrogen of the air still to be
accounted for. With pure oxygen and hydrogen, however, Cavendish
found that pure water was formed, leaving slight traces of any
other, substance which might not be interpreted as being Chemical
impurities. There was only one possible explanation of this
phenomenon--that hydrogen and oxygen, when combined, form water.

"By experiments with the globe it appeared," wrote Cavendish,
"that when inflammable and common air are exploded in a proper
proportion, almost all the inflammable air, and near one-fifth
the common air, lose their elasticity and are condensed into dew.
And by this experiment it appears that this dew is plain water,
and consequently that almost all the inflammable air is turned
into pure water.

"In order to examine the nature of the matter condensed on firing
a mixture of dephlogisticated and inflammable air, I took a glass
globe, holding 8800 grain measures, furnished with a brass cock
and an apparatus for firing by electricity. This globe was well
exhausted by an air-pump, and then filled with a mixture of
inflammable and dephlogisticated air by shutting the cock,
fastening the bent glass tube into its mouth, and letting up the
end of it into a glass jar inverted into water and containing a
mixture of 19,500 grain measures of dephlogisticated air, and
37,000 of inflammable air; so that, upon opening the cock, some
of this mixed air rushed through the bent tube and filled the
globe. The cock was then shut and the included air fired by
electricity, by means of which almost all of it lost its