_magnetic oxide of iron_, of which I have here two small samples. This
magnetic oxide is a good filtering material, but, like every other
filtering material, it would of course require renewal. There would,
however, always be a supply of the waste product--sewage sludge--on the
spot, and the spent magnetic oxide recarbonized could be used
indefinitely.

The annual cost for dealing with the Salford sewage is estimated at in
round figures £2,500 for coal, labor, maintenance of engines, boilers
and dynamos. To this must be added the consumption of iron and its
replacement, which would have to be written off capital expenditure.

If a colorless effluent were required, absolutely free from suspended
matter, the additional cost is estimated at from £1,200 to £1,500.

* * * * *




LAVENDER AND ITS VARIETIES.

By J. CH. SAWER, F.L.S.


Lavender--technically _Lavandula_. This name is generally considered to
be derived from the word _lavando_, gerund of the verb _lavare_, "to
wash" or "to bathe," and to originate from the ancient Roman custom of
perfuming baths with the flowers of this plant.