iting when you use ink.

585. Water will flow over the side of a pan through a siphon,
if the outer end of the siphon is lower than the surface of
the water in the pan.

586. There is a loud noise when a gun is fired.

587. Colored cloths should be matched in daylight, not in
artificial light.

588. Lamp chimneys are made of _thin_ glass.

589. When you sweep oiled floors, no dust flies around the
room.

590. The ocean is salty, while lakes are usually fresh.

591. A glass gauge on the side of a water tank shows how high
the Water in the tank is.

592. You burn your hand when you touch a hot stove.

593. Pounding a piece of steel held horizontally over the
earth and pointing north and south will make it become a
magnet.

594. When only one side of a sponge is in water, the sponge
gradually gets soft all over.

595. If we breathe on a cold mirror, a fine mist collects on
it.

596. Butter is kept in cool places.

597. Water will boil more quickly in a covered pan than in an
open one.

598. Mucilage, glue, and paste all become hard and dry after
being spread out on a surface for a while.

599. You cannot see things clearly through a dusty window.

600. In making fire grates it is necessary to have the bars
free to move a little.

APPENDIX

A. THE ELECTRICAL APPARATUS

For giving children a practical understanding of such laws of
electricity as affect everybody, the following simple apparatus is
invaluable. It is the electrical apparatus referred to several times
in the text. The only part of it that is at all difficult to get is
the nichrome resistance wire. There is a monopoly on this and each
licensee has to agree not to sell it. It can be bought direct from the
manufacturer by the school board if a statement accompanies the order
to the effect that it is not to be used in any commercial devices,
nor to be sold, but is for laboratory experimentation only. The
manufacturers are Hoskins Manufacturing Company, Detroit, Michigan.

The following diagram will make the connections and parts of the
electrical apparatus clear:

[Illustration: FIG. 190. Electrical apparatus: At the right are the
incoming wires. Dotted lines show outlines of fuse block. _A_, 2
cartridge fuses, 15 A; _B_, 2 plug fuses, 10 A; _C_, knife switch;
_D_, fuse gap; _E_, snap switch; _F_, _H_, lamp sockets; _G