** White Putty to Black [376]

White putty on a black window frame can be made to harmonize by rubbing the fresh putty with a piece of cotton dipped in lampblack.

** Using Sandpaper [376]

Sandpaper may be kept from slipping under the hand by chalking the back.

** An Interesting Electrical Experiment [377]

Anyone possessing a battery having an electromotive force of from 4 to 20 volts can perform the following experiment, which is particularly interesting on account of the variation of results with apparently the same conditions.

Immerse two pieces of brass in a strong solution of common salt and water.  Connect one piece to the positive wire and the other to the negative, taking care that the brass pieces do not touch each other.

After the current has passed one

[Illustration:  How Wires are Connected]

or two minutes, the solution will become colored, and if the process is continued a colored pigment will be precipitated.  The precipitate varies considerably in color and may be either yellow, blue, orange, green or brown, depending on the strength of the current, the strength of the solution, and the composition of the brass.

** Novelty Chain Made from a Match [377]

The accompanying engraving shows what is possible to do with a penknife.

[Illustration:  Lay a Match on the Picture]

A small chain composed of several links was cut from the wood that forms the match.

** Keeping Doors Closed [377]

Glass doors in bookcases may be kept from swinging open by boring a hole, about 1/4 in. deep, either at the top or bottom in the edge of the door, 2 in. from the closing edge, and inserting an ordinary cork, allowing a small portion to project and rub on the facing.

** Restoring Broken Negatives [377]

Whoever has the misfortune to break a valuable negative need not despair, for the damage can be repaired most effectively.  In case the negative be broken into many pieces, take a clean glass, the same size as the broken negative, and put upon this the pieces, joining them accurately, says Camera Craft.  Put another clean glass on top of this and bind the three together with passe-partout binding or gummed strips of ordinary paper, as one would a lantern slide, and cover the glass edges.

Next make a transparency of this—­in the camera, of course—­and if it is done right, the positive will only show the cracks as dark and light lines.  The

[Illustration:  Before and After Mending]

dark lines are removed with the etching knife and the light ones with the retouching pencil.  From this transparency another negative can be made, or as many negatives as necessary, by either contact or in the camera, and if the work on the glass positive was done carefully, no trace of the break should be seen on the finished negative.  If the negative is broken in two or three larger pieces only, a contact positive may be made in the printing frame without binding, by using a clean glass in the latter, upon which the pieces are put together, face up, and a dry plate exposed in contact with them in the dark room.  The accompanying engravings show a print before and after repairing a broken negative in this manner.