qual the weight of the
hydrogen present in the water formed.

[Illustration: Fig. 22]

~Dumas' results.~ The above method for the determination of the
composition of water was first used by Berzelius in 1820. The work was
repeated in 1843 by Dumas, the average of whose results is as follows:

Weight of water formed 236.36 g.
Oxygen given up by the copper oxide 210.04
------
Weight of hydrogen present in water 26.32

According to this experiment the ratio of hydrogen to oxygen in water is
therefore 26.32 to 210.04, or as l to 7.98

~Morley's results.~ The American chemist Morley has recently determined
the composition of water, extreme precautions being taken to use pure
materials and to eliminate all sources of error. The hydrogen and oxygen
which combined, as well as the water formed, were all accurately
weighed. According to Morley's results, 1 part of hydrogen by weight
combines with 7.94 parts of oxygen to form water.

~Comparison of results obtained.~ From the above discussions it is easy to
see that it is by experiment alone that the composition of a compound
can be determined. Different methods may lead to slightly different
results. The more accurate the method chosen and the greater the skill
with which the experiment is carried out, the more accurate will be the
results. It is generally conceded by chemists that the results obtained
by Morley in reference to the composition of water are the most accurate
ones. In accordance with these results, then, _water must be regarded as
a compound containing hydrogen and oxygen in the proportion of 1 part by
weight of hydrogen to 7.94 parts by weight of oxygen_.

~Relation between the volume of aqueous vapor and the volumes of the
hydrogen and oxygen which combine to form it.~ When the quantitative
synthesis of water is carried out in the eudiometer as described above,
the water vapor formed by the union of the hydrogen and oxygen at once
condenses. The volume of the resulting liquid is so small that it may be
disregarded in making the calculations. If, however, the experiment is
carried out at a temperature of 100 deg. or above, the water-vapor formed is
not condensed and it thus becomes possible to compare the volume of the
vapor with the volumes of hydrogen and oxygen which combined to form it.
This can be accomplished by surrounding the arm A of the eudiometer
(Fig. 23) with the tube B through