HOW TO UTTIZE POLEUTING MATTERS. 61 
and stains the very beds and banks of the streams the 
colour of a mahogany table. But Mr. Pughsley, of 
Kidwelly, has devised a means of utilising this waste 
“pickle,” by the use of which, instead of dealing death and 
destruction in the rivers, it may be retained in the factories, 
and become a source of wealth. Mr. Pughsley simply 
evaporates the water from the pickle by boiling, and 
recovers the acid, so that it may be used over and over 
again, while the iron, combining with a portion of the acid, 
is precipitated in the form of green copperas or sulphate of 
iron, a valuable commercial commodity. 
In much the same way the waste soda or chloride of 
lime from paper works, the alkali from soap works, the 
grease from wool works, the waste from dye works, and 
the thousand and one other forms of poison daily cast into 
our rivers, may, by the practical application of the teachings 
of science, be diverted from the streams which they pollute 
and converted directly into money. For example, the 
refuse from tan-yards is a fruitful source of pollution, but 
there is no reason why the rivers should receive this matter, 
which, if applied to the land, is a valuable manure. The 
dye-water from dye works, consisting of a solution of 
sulphate of iron, with insoluble dye-matter in suspension, 
can be purified in a very easy manner, and the refuse 
used as manure; it can be clarified by simple filtration 
through ashes ; or, if turned into subsiding pits or tanks, the 
addition of a little lime causes the colouring matter to be at 
once precipitated, and the superincumbent water is left clear, 
and may be drained off comparatively pure and colourless, 
instead of going to foul the river and unfit its waters for 
use by manufacturers and others below. 
This last consideration is a most important one. Even 
if manufacturers had no inducement, in the actual value of 
