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MIXING METALS.--All the hard gray American charcoal iron, of which
car wheels and all such work are made, requires more heat and a longer
time to melt than soft iron, especially Scotch pig, which is the most
fluid and the easiest to melt of any iron. Consequently, unless the
melter exercises good judgment in charging, the Scotch pig will
melt and run off before the car-wheel iron is melted. If G. H. P.
be particular in the quality and strength of his iron, he will make
better results by using soft American charcoal pig, with old car-wheel
iron. It will make stronger castings, mix better, and melt more
uniformly; but he should always recollect in charging his furnace that
soft iron will melt before hard in the same position, in the cupola. I
also think he had better use a larger proportion of soft pig, as every
time cast iron is melted it becomes harder, so much so that iron which
can be filed and turned with ease, when re-cast will often be found
too hard to work.--J. T., of N. Y.
HARDENING TALLOW.--If E. H. H. will use one pound of alum for every
five pounds of tallow, his candles will be as hard and white as wax.
The alum must be dissolved in water, then put in the tallow, and
stirred until they are both melted together, and run in molds.--F. O.
H.
L. L., of N. Y.--According to Ure, strass is made as follows: 8 ounces
of pure rock crystal or flint, in powder, mixed with 4 ounces of
salt of tartar, are to be baked and left to cool. The mixture is then
poured into hot water, and treated with dilute nitric acid till it
ceases to effervesce, and the "frit" is then washed in water till the
water comes off tasteless. The frit is then dried, and mixed with 12
ounces of white lead, and this last mixture reduced to fine powder,
and washed with distilled water; 1 ounce of calcined borax is now
added to every 12 ounces of the mixture, the whole rubbed together in
a porcelain mortar, melted in a clean crucible, and poured out into
pure cold water. This melting and pouring into water must be done
three times, using a clean, new crucible each time. The third frit is
pulverized, five drachms of niter added, and then melted for the last
time, when a clean, beautiful white crystal mass results.
C. M. S., of Wis.--There are no precise proportions observed in
making the coal-tar and gravel walks of which you speak. The aim is to
saturate the gravel with the hot tar without surplus. The interstices
of the gravel are simply to be filled, and the amount required to
do this depends wholly upon the coarseness or fineness of the gravel
employed.
W. P. T., of Ohio.--Two teams of horses, of equal strength, pulling
against each other, by means of a rope, would create the same tension
in the rope, as one of the teams drawing against an immovable object.
W. H. B., of Va.--Ice can be made by compressing air, and, after it
has radiated its heat, allowing it to extract the heat of water with
which it is brought into contact. The temperature of air at 59 deg. Fah.,
would be raised, by compressing the air to one fourth its original
volume, to 317 deg. Fah; and the air would radiate and absorb again, in
expanding, about 190 units of heat.
E. T. H., of Ga.--The friable sandstone, a specimen of which you send
us, may, we think, be rendered firmer by soaking it in a solution of
silicate of soda, and allowing it to stand till dry.
J. A. V., of Ohio.--The use of steam expansively, by means of cut-off
appliances, enables the expansive force of the steam to be utilized,
which cannot be done when the pressure is maintained at one standard,
and steam admitted through the fall stroke. It takes no more power
to do a given amount of work in one case than in the other, but more
boiler capacity, and more fuel, as the working power of the steam is
more economically applied when the cut-off is used.
Geo. F. R., of Ohio.--Type metal is composed of 3 parts lead and 1
part antimony for smallest, hardest, and most brittle types; 4 of
lead and 1 of antimony for next grade; 5 of lead and 1 of antimony for
medium sizes; 6 of lead and 1 of antimony for larger types; and 7 of
lead and 1 of antimony for the largest.
E. J. M., of Texas.--The term "power of a boiler" means its
evaporating power, and in that sense is proper. If its evaporative
power be sufficient to perform a given amount of work, it is proper
to estimate that work in horse power. Water can not be pumped out of a
pipe from which atmospheric air is excluded. A pipe driven into a soil
impervious to air, can never yield water unless the water is forced up
by hydraulic power, as in the artesian system.
A. P. Y., of N. Y.--You will find descriptions of iron enamelling
processes, on pages 297 and 408, Vol. XII. of this journal. It can be
done in colors. See Ure's "Dictionary of Arts and Manufactures."
H. C., of Pa.--We do not think increasing the size of the journals of
your car axles from 21/2 inches to 6 inches diameter, would make them
run lighter.
H. H. A., of N. Y.--The lining up of a beam engine, in a vessel, is
a process for which no definite mode of procedure is exclusively
applicable. It is an operation to which common sense and judgment must
be brought, and for which each engineer must be a law unto himself.
J. S., of Va.--The use of horizontal propellers to force balloons up
or down is not a new suggestion. It has been tried, but, we believe,
without much practical success.
J. T .S., of N. Y.--You will find further information on the subject
of transmitting power by compressed air, in our editorial columns of
last week.
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