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28
the standard light required by the Act. With respect to
purity, all the gases were free from sulphuretted hydrogen,
and so far free from ammonia, that they did not discolour
the turmeric paper, except on November the 15th, when both
the gases supplied by the Chartered Company discoloured
the turmeric, paper in consequence of an excess of ammonia.
I immediately wrote to the engineer of the Company complaining
of the impurity of the gases, which was subsequently
remedied.
The following Table gives the average light in sperm
candles of all the gases—
Chartered. London. Equitable.
Cannel 23.85 23.81 24.73
Common 14.29 14.2 15.04
A Table and Summary were sent with each Monthly
Report on the gas to the Vestry, containing the number of
examinations, with the dates, and the maximum and minimum
light, with the weekly and monthly average illuminating
power.
C. J. B. Aldis, M.D.,
Gras Examiner.