View report page

48
Sewer; and secondly, an insufficient number of ventilating
shafts. The depression is estimated to contain 620 gallons,
and when full measures in its deepest part 10 inches.
Nothing is discharged into it except from the inlet of the
Oil Refinery, and below the Drop from the drains of three
small houses. Six tons of waste water from the Refinery,
or, in liquid measure, 2,350 gallons, are poured daily over
the Drop, and are precipitated into the head of the depression
lying 2 feet below. The flow is intermittent, each
discharge lasting about 20 minutes.
The volume discharged daily is sufficiently large to displace
twice over the residual matters accumulating in the
depression. The residual matter is chiefly water, but
beneath the surface fluid a deposit collects from one inch
to one and a half in thickness.
TESTING THE RESIDUAL SEWAGE.
On the morning after the accident a sample was taken
from this depression for analysis, and the sewage was
found to contain a ten per cent. admixture of sulphuretted
hydrogen. The analysis also showed the presence, but in
smaller quantity, of free sulphuric acid and sulphate of
iron.*
Much depends on whether this sample fairly represented
the ordinary and normal condition of the residual contents
of this Sewer, in other words, whether sulphuretted hydrogen
in quantity was a product and constant constituent, or
whether its presence on this occasion was accidental.
If it can be shown that the sludge of the Sewer
generates sulphuretted hydrogen gas in quantity
and afterwards serving as a magazine holds it in
* Vide Appendix No. 1.