Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1881-06-04
TRY IT AT HONE.
Some Interesting Preside Electrical Ex-
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TRY IT AT HOME.
Some Interesting Preside Electrical Ex-
periments Easily Performed.
Readers of the RECORD UNION, and
younger ones especially, will remember
the series of home experiments in science
which we gave in these columns not long
ago. Herewith are few more, and all
will well repay for the effort involved:
During a lecture course by professors
who have at their disposal a complete set
OF physical apparatus, there are some ex-
periments performed by them which at
first sight seem very complicated, but
which nevertheless may be repeated ly
means of very simple objects. There is,
fer instance, the interesting Lissajous ex-
pertinent, which consists in throwing on a
screen, by means of the oxyhydrogen lamp,
the curves traced by one Of the arms of a
tuning-fork in sonorous vibration. An
analogous experiment may be exhibited by
means of common khitting-needle. FIX
one of the extremities of the needle in a
cork to serve as base; then to the
upper free extremity attach a ball of seal
ing wax, and on this gum a small circle OF
paper about the diameter of a pea. Now,
holding the cork firmly between the fingers
| OF the left hand, cause the needle to sharp.
| ly vibrate, either by bending it far to one
side and then suddenly releasing it, or by
striking it smartly witAa wooden ruler.
| The little ball Of wax surmounted by paper
will be seen to describe more or less
elongated ellipse, or circle, according to
| the intensity or the number of Vibrations
The phenomenon is very perceptible when
care is taken to cause the needle to vibrate
under strong light from lamp; and in
such case the persistence of the impress
sion on the retina causes the vibrating wire
to form an image which has the appearance
of a long and graceful bonquet-holder, or a
champagne-glass.
| Among the experiments sometimes per-
| formed to demonstrate molecular attrac-
| ton, there is one which is executed by
means of an apparatus of peculiar struc.
ture; but the same phenomena may be
shown in much more simple manner, as
follows: Having cut two small spheres out
of bottle cork, place them on the surface
of water. If one of the balls now carefully
be pushed along until it is in quite close
proximity to the other, the two will be
seen to quickly rush toward each other,
lust as bit of iron flies to magnet when
the latter is brought near it, The expert
ment may be varied by fixing one of the
balls to the point Of knife and using it to
attract the other ball when floating at a
short distance.
In former article has been described
how an electric spark may be obtained by
means of sheet of paper and a bunch OF
keys. 4 writer in a recent number of Ma
ture has pointed ont neat method Of OBJ
tanning the same result by means of a
simple apparatus which he calls the " tea
tray electrophorus." a common metallic
tea. tray Is supported on two dry glass
goblets. A piece of common brown paper
cut so as ID be little smaller than the
tray, and with rounded corners, is warmed,
laid on the table and rubbed briskly with
q piece OF India. rubber, or with clothes
brush. 1t is then laid down for an instant
on the tray, and the latter is touched with
the hand. The paper is then lifted a few
inches above the tray. Ii at this juncture
some person presents his knuckle to the
tray he will receive bright spark, which,
under favorable circumstances. may be a
couple of inches long. By simply putting
the paper down, touching the tray, aud
again lifting up the paper, the tray is again
charged, and large number of sparks may
thus be drawn one after the other IN rapid
succession. The paper may be lifted by
the hands, but it will be found better if a
couple of strips of paper be fixed on with
wax to serve as handles.
Tie sparks obtained by the tea-tray
electrophorus may produce slight prick
ing sensation, but to give a regular electric
shock. will oblige us to store up a charge
in a Leyden jar. This important piece of
apparatus may be improvised as follows ::
A round bottomed glass tumbler is pro-
cured-thin glass is preferable is
filed about three-quarters full OF small
leaden shot, Ii shot is not at hand dry
coal dust will answer, though not so we'll,
and great care must be taken towlpe clean
the upper part of the tumbler. Every
thing must be warm and scrupulously dry.
Into the shot is inserted a silver spoon to
serve the place of rod and knob. The
tumbler is held by grasping it well
in the bottom of the hand, SO that the
palm may cover the whole Of the rounded
bottom. Having thus prepared and
grasped the improvised Leyden jar, it is to
be charged with sparks from the tea.tray
electrophorus. 1t should be held with the
spoon handle near to, but not quite touch
ing the edge of the tea tray, while another
person performs the operations of lifting
the paper up and putting it down, then
touching the tray, then lifting it up again,
and so on until dozen sparks have been
sent into the jar. On touching the knob"
smart little shock is experienced in the
wrists and elbows, and short, bright,
swapping spark announces the discharge of
the jar.
Hall fiji long, narrow glass tube with
water; upon this pour alcohol until it is
full. Close the tube with the thumb, in
vert it, and shake so as to mix the liquids.
The tube is no longer full, while none of
the liquid has escaped. The molecules OF
water must have entered into little spaces
between the molecules of alcohol, and
vice versa.
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