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178
alteration of the law. The gas referees, it was stated, approve of
the testing of the gas by means of a portable photometer; and the
Metropolitan Board advised the Board of Trade that statutory
power should be obtained for that mode of testing, so that the
companies may be liable to forfeitures for gas which the portable
photometer shows to be defective in lighting power.
The Board also suggested the expediency of an alteration in
the standard of light prescribed by the statutes. The statutory
standard is obtained by burning a sperm candle of six to the
pound, at the rate of 120 grains an hour; and the gas is
required to be of such lighting power as to produce,
when consumed at the rate of five cubic feet an hour, a
light equal to that produced by sixteen such candles. A
Committee, appointed by the Board of Trade, reported adversely
to the continuance of the use of the sperm candle as a standard,
it having been proved that, in spite of precautions taken to
secure uniformity in the manufacture of the candles, there
remained considerable variation in their lighting power.
In the Reports of the Board for 1885 and 1886, no reference
was made to the important matters dealt with in the above
paragraph, but in the Report for 1887, the subject was again
dealt with, and we were informed that in the interval a long
series of careful and complete experiments had been made by the
Officers of the Board, under the Board's authority, with the
result that the Pentane air-gas standard, as devised by Mr. A.
Vernon Hareourt, one of the gas referees, appeared to possess,
in a higher degree than any other, the merits of simplicity,
accuracy, and reliability. These subjects doubtless will
receive attention from the County Council
2. As regards purity. The gas was free from sulphuretted
hydrogen throughout the year; and the quarterly average
quantity of other sulphur compounds present in the gas was
considerably less than the quantity permitted, the maximum
moreover not having been attained on any occasion.