before inserting them in the holes. Fill the
can with crude oil, or with any kind of oil except kerosene

[Illustration: Parts of the Transformer]

oil, and immerse the magnets in it by fitting the cover on tight
(Fig. 3). The connections are made as shown in the diagram, Fig.
5. This device may be used on 110-volt current for electro-plating
and small battery lamps, provided the magnets are wound with wire
no larger than No. 40.
--Contributed by C. M. Rubsan, Muskogee, Okla.

** Experiment with a Vacuum [439]

[Illustration: Experimental Apparatus]

Take any kitchen utensil used for frying purposes-an ordinary
skillet, or spider, works best-having a smooth inner bottom
surface, and turn in water to the depth of 1/2 in. Cut a piece of
cardboard circular to fit the bottom of the spider and make a hole
in the center 4 in. in diameter. The hole will need to correspond
to the size of the can used. It should be 1 in. less in diameter
than that of the can. Place this cardboard in the bottom of the
spider under the water. A 2-qt. syrup can or pail renders the best
demonstration, although good results may be obtained from the use
of an ordinary tomato can. The edge of the can must have no
indentations, so it will fit perfectly tight all around on the
cardboard. Place the can bottom side up and evenly over the hole
in the cardboard. Put a sufficient weight on the can to prevent it
moving on the cardboard, but not too heavy, say, l lb.

Place the spider with its adjusted contents upon a heated stove.
Soon the inverted can will begin to agitate. When this agitation
finally ceases remove the spider from the stove, being careful not
to move the can, and if the quickest results are desired, apply
snow, ice or cold water to the surface of the can until the sides
begin to flatten. The spider with its entire contents may now be
lifted by taking hold of the can. When the vacuum is complete the
sides of the can will suddenly collapse, and sometimes, with a
considerable report, jump from the spider.

The cause of the foregoing phenomenon is that the circular hole in
the cardboard admits direct heat from the surface of the spider.
This heat causes the air in the can to expand, which is allowed to
escape by agitation, the water and the cardboard acting as a valve
to prevent its re-entrance. When the enclosed air is expelled by
the heat and a vacuum is formed by the cooling, the above results
are obtained as described.
--Contr