§ 321. Standard of illuminating power. The maximum illuminating power
required and minimum illuminating power permitted of gas so furnished or
supplied in any such city shall be as follows: If a coal gas, sixteen
candles; if a mixed coal and water gas, eighteen candles; and if a
carburetted water gas, twenty candles. A candle shall mean a sperm
candle, six to a pound, burning at the rate of one hundred and twenty
grains of spermaceti per hour. The test for illuminating power shall be
made with gas obtained from a service pipe or main located at a distance
of not less than one mile nor more than one and one-half miles from any
distributing holder, using, for coal gas and mixed coal and water gas
containing more than fifty per centum of coal gas an F Argand burner,
and for mixed coal and water gas containing fifty per centum and less of
coal gas and for carburetted water gas a number seven slit union Bray
burner, on a basis of consumption of five cubic feet of gas per hour.