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13
Purity.
Ammonia.—The quantity has varied, but has never
exceeded from ½ to 3 grains per 100 cubic feet—the
last testing showing only half a grain—the maximum
quantity permitted by the Gas Referees under the City
Gas Act of 1868, but which does not apply to the Commercial
Company, is five grains of ammonia to 100 feet
of gas, this standard has probably been somewhat arbitrarily
fixed. The Act of 1860, which rules the Commercial
in common with other Companies, does not
prescribe any specific quantity of ammonia, but provides
for a mode of paper-testing by which all Gas Companies
would be repeatedly liable to conviction if the quantity of
ammonia were only one-fifth part of the amount allowed
under the City Companies Act of 1868—the test is
delicate, and shows the presence of an infinitesimal proportion
of ammonia. It has occurred during several
successive days that this test has failed to detect the presence
of any ammonia in the Commercial Company's gas.
Sulphuretted Hydrogen has never been present.
Sulphur.—Under the Act of 1860, 20 grains to 100
cubic feet is the maximum quantity allowed for this
impurity. At that period, I believe, it was found quite
impracticable to manufacture gas that should with any
degree of certainty contain only this amount of sulphur.
Hence the City Act of 1868 does not prescribe any
specified amount but confers upon referees the power
to fix from time to time, as in the case of ammonia, the
quantity of sulphur which shall be ligitimately present
in the gas. The last testing showed 23 grains of bisulphide
of carbon to 100 cubic feet in the Commercial
Company's gas, but the average of numerous testings
was only 18½ grains. From this short review of gas
testing it will be seen that gasology has not yet
attained the position of an exact science.