contains a
great number of hydrocarbons--naphtha, naphthalen, anthracen, phenol,
several organic alkaloids, hydrosulphuric and hydrocyanic acids, etc.,
all of which are more or less volatile at the temperature to which
they must have been subjected. These exhalations have proved fatal to
plant life when in sufficient quantity. We do not know of a better
remedy than that of removing the cause. Painting the pipes with a
strong solution of washing soda and lime would, in a measure, prevent
the escape of the most objectionable constituents into the air, by
forming with them compounds non-volatile at any temperature to which
they are likely to be subjected in contact with the pipes; but the
former would be the surest plan.

(4) C.D.W. asks: The roof of the new Illinois State House, as well as
the stylobate cornices and upper portion of the dome, are covered with
zinc. It has been on about three years, and I am told is materially
affected by oxidation. The theory is that zinc, though subject to
oxidization, has the peculiarity that the oxide does not scale off as
from iron, but forms a permanent coating impervious to the action of
the atmosphere. Some mechanics, however, assert that neither zinc,
copper, nor lead will withstand the action of our atmosphere, as
bituminous coal strongly impregnated with sulphur is almost the only
fuel used. It is claimed by some that the sulphurous acid in the
atmosphere tends to corrode zinc so as to make it worthless for roofs
or gutter linings. A. Are you sure that the roof and gutters in
question are not of galvanized iron, iron coated with zinc? This is
the material most commonly used for that purpose at the present time.
Zinc has been found to be too brittle for the strain to which it is
subjected, in such cases, by the expansion and contraction induced by
changes of temperature. A slight oxidation will adhere to the surface,
but an acid deposit from the atmosphere will penetrate the coating in
points and deteriorate the metal.

(5) N.J.S. says: I have a floor of ash and black walnut which has been
oiled with raw linseed oil once. How can I finish it so as to get a
hard, smooth finish that will not be scratched by boot heels nor be
sticky or retain the dirt as a waxed floor does? A. Oil raises the
fiber of black walnut and gives it a rougher surface than when free
from it. To polish any wood, it is only necessary to fill the pores
well, and then rub it down to a smooth surface. Thus pai