============+==============
| | APPROXIMATE | PERCENTAGE OF | PART OF
| DENSITY BY | MOLECULAR | NITROGEN BY | MOLECULAR
| EXPERIMENT | WEIGHT | EXPERIMENT | WEIGHT DUE
| | (D. x 28.9) | | TO NITROGEN
------------------+------------+-------------+----------------+--------------
Nitrogen gas | 0.9671 | 27.95 | 100.00 | 27.95
Nitrous oxide | 1.527 | 44.13 | 63.70 | 27.11
Nitric oxide | 1.0384 | 30.00 | 46.74 | 14.02
Nitrogen peroxide | 1.580 | 45.66 | 30.49 | 13.90
Ammonia | 0.591 | 17.05 | 82.28 | 14.03
Nitric acid | 2.180 | 63.06 | 22.27 | 14.03
Hydrocyanic acid | 0.930 | 26.87 | 51.90 | 13.94
==================+============+=============+================+==============

~Method of calculation.~ The densities of the various gases in the first
column of this table are determined by experiment, and are fairly
accurate but not entirely so. By multiplying these densities by 28.9 the
molecular weights of the compounds as given in the second column are
obtained. By chemical analysis it is possible to determine the
percentage composition of these substances, and the percentages of
nitrogen in them as determined by analysis are given in the third
column. If each of these molecular weights is multiplied in turn by the
percentage of nitrogen in the compound, the product will be the weight
of the nitrogen in the molecular weight of the compound. This will be
the sum of the weights of the nitrogen atoms in the molecule. These
values are given in the fourth column in the table.

If a large number of compounds containing nitrogen are studied in this
way, it is probable that there will be included in the list at least one
substance whose molecule contains a single nitrogen atom. In this case
the number in the fourth column will be the approximate atomic weight of
nitrogen. On comparing the values for nitrogen in the table it will be
seen that a number which is approximately 14 is the smallest, and that
the others are multiples of this. These compounds of higher value,
therefore, contain more than one nitrogen atom in the molecule.

~Accurate determination of atomic weights.~ Molecular weights cannot be
determined very