On the whole it is probable that most of the
dye stuffs are passed into streams in such a diluted condition, and there become so much more diluted,
that they do not kill the fish. This is borne out by
what is found in the river Leven, in Dumbartonshire,
which is polluted by effluents from Turkey Red works..
It is said that,in this case, the dye stuffs have no
effect on the fish which are injured by caustic and
other substances employed in the process. Quite
apart from any fatal result however the fish may suffer in health from fungus growth, while deposits are
likely to occur, and as it would seem that simple
methods can obviate these undesirable effects, their
use should be enforced.
As is shewn in the experiments with mill
effluents and stream waters filtration or simple precipitation apparently renders the effluents innocuous.
In the case of the Tweed, trout are frequently caught
at a point just below where the mill discharges take
place, and no objection can be taken to the condition
of the river water, although as will be seen by reference to the tables, the dyes and substances mixed
with than are very fatal.
Indigo effluents, even when foul smelling,
did not kill fish and must be regarded as non toxic;
but most of the Yorkshire rivers in the factory districts are in a disgraceful state. Dr Maclean Wilson, Medical Inspector to the West Riding Rivers
Board, to whom I am indebted for the samples he sent
me, has however devoted attention to the existing
state of affairs, and improvement may be looked for.
I must also express my thanks to Oscar Schofield Esq.
of Littleboro' Lancashire, who sent me samples containing vegetable dyes and mordants. Such a sample
was rapidly fatal, but after filtration its toxic
properties entirely disappeared. He employe Kremmolite, a form of iron ore for the purpose and from my
results it would seem to act admirably.
It is.probable therefore that careful filtra¬
tion or precipitation is all that is required, with
a sufficient staff of inspectors to see that, what¬
ever process is adopted, it is efficiently carried
out. Till this is done, not only in connection with,
dye's and mordants, but also with other forms of
stream pollution, the great dream of Frank Buckland's
life is not likely to be realised.