The true northerner. [volume] (Paw Paw, Mich.) 1855-1920, 1885-10-08
MECHANICAL.

A NEW bridge n to be constructed
over the river Thames opposite the
Tower of London. The center arch Of
the bridge is to be capable of opening
so as to admit of the passage of yes
sells, and during the opening pedestrian
traffic will be carried on over high
level arch. The time occupied by the
opening Of the bridge, the passage of
the vessel, and the closing, is estimated
at less than five minutes. The cost of
the work will be 81, 250,O00.
BERLIN post-boxes are painted blue
and gold, and measure about two feet
each way. They are not fastened to
lamp-posts, but to buildings. The let
ter apertures are guarded by movable
spikes setting inward. On the face the
hours of clearing are given, and dial
moved by key shows the next
dispatch. The district station to which
the box is attached is also shown, so
that q stranger learns at once the near
est Office where postal business is trans
acted. In all but the suburban parts
of Berlin these street boxes are cleared
twenty times between 5:45 a. m. and
10 p. m.
GRAPE-sEED oil is used in Italy for
purposes of illumination. The extrac-
ton is principally effected at Modena
1t has also long been used for similar
purposes in Germany and the Levant
Thirty-three pounds of seed will yield
about thirteen quarts of oil, or about
Is per cent. The seeds of white grapes
yield less oil than those of the dark
variety, and young vines are said to be
more fruitful in this respect than older
ones. AS to the French varieties, the
Rossilar, Aube, and Herault seeds yield
2 per cent. more than the Bordeaux
seeds. The color is golden yellow,
and the oil loses about 25 per cent. in
publication.
NM. HAUTEFEULLE and Chappuis
have found that ozone is blue gas, the
color appearing sky blue even when
only so much ozone is present as is OBJ
tanned in the ozonation of the oxygen
contained in tube meter in length
by the silent discharge. Furthermore,
they find that, under very great pres
sure, the condensed gas becomes indi-.
go blue. If the pressure is increased
to seventy-five atmospheres, and then
suddenly relieved, dense white cloud
is formed, showing the beginning of
liquefaction, while the same phenome-
non does not take place with pure oxy-
gen until a pressure of 800 atmospheres
is attained. The ozone must be COM
pressed slowly and with constant cool
ing, otherwise it will explode with evo-
the ozone with carbon dioxide, and
then submitting the mixture to great
cold and pressure, these chemists have
obtained deep-blue liquid, the blue
color being due to the iquefed ozone.
Among the conclusions they arrive at
is that ozone is the cause of the blue
color of the sky.
The longer oil is kept the better,
both as regards drying and transparent
qualities. To make good nut oil, the
skin of ripe walnuts should be peeled
off, as it contains an acid which turns
it brown. Poppy oil is made from the
ripe seed of peoples. 1t is the best
drying oil. The oil of spike, or laven-
der, is obtained by distilling spike with
water; it is very volatile, and fine for
working with the pencil, or for enamel
ing To make a good drying oil for
extra fine painting, take of poppy oil
or nut oil one pint, of gum sandarac
two ounces, of white vitriol and sugar
of lead each one ounce. Boil the whole
till the solid ingredients are dissolved,
and the mixture is the color OF inseed
oil. This oil will dry fast, and a por-
ton of turpentine added makes fine
oil for use when the purest white tint
is required. 1t may be mixed with
other oils as drying, where common
drying oil would be injurious to the
color. Raw linseed oil for woodwork
is best, as, being more volatile than
boiled oil, it strikes into the wood and
forms hard, resinous filling.
RnuInl;c.,, In, Goufh Woloc