Amador ledger., 1909-08-13

The destruction of weeds bv spray
ing was begun in North Dakota in
1896 by Prof. II. l.. Bolley, who is
widely known also for his researches
in plant diseases. tie sprayed grow
ing wheat with solutions of copper
sulphate and merourio bichloride,
and found that the tops OF both grain
and weeds turnei black, but the
former revived in two or three days,
while young mustard and other weeds
withered and died. The difference
in effect is attributed to the fact that
the broad, rough and soft leaves of
the weed retain much of the chemi-
Gals, which run of harmlessly from
the smooth and slender stalks of
grain. For sulphate of copper has
been substituted the cheaper sulphate
of iron. of which many tons are now
used, killing most weeds without in
jury to grain, including false fax,
shepherds purse, peppergrass, corn
cookie, chiokweed, dandelion,
Canada thistle, bindweed, plantain,
pigweed, ragweed and others. A
solution of two pounds of Esulphate
of iron In a gallon of water has been
found effective in similar way for
freeing lawns from young dandelions.
Buildings without windows have
received favorable consideration for
the sbook- stacks of Libraries. Day
light is injurious to books, and be-
sides this the windowless structure
offers such advantages AS reduced
cost, better protection against fire,
exclusion of dust, greater con-
venience In changing the arrangement
of the books, and more equable
peIature. AS library stacks are
mostly hidden behind other buildings
the unattractiveness of the plain
walls is not serious objection.
Forced ventilation would give pure
air, and artificial light could be turn
ed on at will.
Considering that circular struct-
ures best resist earthquake shocks,
Prof. Giuseppe forres, of Venice, has
designed a house, for earthquake re-
gIons, consisting CT several circular
turrets nf different diameter COM
municating with each other. This
seems more artistic than economical.
In tho unique and avdanced
museum idea of DIR. Goldschmidt Of
inert models and bring the public
into contact with science in action.
inviting visitors to test and use ap-
paratus Instead of labelling it "Don't
hardle.'' His first efforts have been
applied to a popular electrical labor
atory. This is divided into graded
sections. so that the visitor may first
experiment with sealing wax or mag
nets. then with electric generators
and motors, passing further along to
tubes in which he may show cathode
rays and other electrical discharges
and the effects of radium, and reach
ing finally the instruments for pre-
else measurements. in section COM
petent assistants perform the tests,
although sufficiently trained visitors
are permitted to use the instruments.
Some of the more delicate apparatus
is kept under glass, leaving exposed
only such parts as must be handled
IN making the experiments. There
is mechanical workshop where any
person may gain experience In con-
struotinS electrical apparatus, four
small laboratories for personal re-
search by specialists, a hall for the
free exhibition OF industrial pro-
ducts, a lecture hall where pressing a
button causes 100 successive scien
titic views to be thrown on screen
aud library OF the principal scien-
tItio books and periodicals.
In factories where needles are
made, the grindstones throw of great
quantities of minute steel PARTICLES,
with which the air Ebecomes heavily
charged, although the dust is too fine
to be peroeptible to the eye. Breath
lug the dust shows no Immediate
effect, but gradually sets up irri'
tation. usually ending IN pulmonary
consumption, and formerly workmen
almost all died before the age of
forty. Ineffective attempts were
made to screen the air by gauze or
linen guards tor nose and mouth.
At last the use of the magnet was
suggested, and now masks of mag