-needles, harness-needles, hack-saw blades, sewing-needles,
etc., are generally made of a good quality of steel.

292. Zinc, in the sheet form, can be bought at a hardware store. For a
few cents you can get quite a large piece. Get the thick pieces for
heavy battery-plates of an electrician. You do not need anything that is
thicker than 1/8 in. The zinc rods are usually amalgamated.

293. Lead can be bought at a plumber's, tinsmith's, or hardware store.
You may want some for a storage cell.

294. Nails. Wire nails are best for light work. Get an assortment from
1/2 in. long up to 1-1/2 in.

295. Screws. It is better to use brass screws around electrical
apparatus. For the small work, for binding-posts, etc., use 5/8 No. 5.
Another handy size is No. 7, from 3/4 to 1-1/4 in. long. The
round-headed screws are best, unless you want to countersink them.

296. Tin. This is really thin sheet-iron, covered with tin. Save up
tomato-cans, cracker-boxes, condensed-milk cans, etc. The cracker-boxes
are just as good as sheet-tin, as the pieces are large and clean. You
can remove the solder from cans by heating them in the kitchen fire.
Knock out the bottoms with a poker when the solder gets soft. Clean the
tin with sand-paper.

297. Carbons. You can get carbon rods or plates at an electrician's. If
you have arc electric lights in your city, you will be able to pick up
carbons; these, however, generally have a coating of copper, which must
be eaten off with dilute nitric acid. This is a bother. You will find it
cheaper to buy the 1/2 in. rods that are 12 in. long, and uncoated.

298. Shellac. Your wood-work will be much improved by using shellac upon
it after you have thoroughly sand-papered it. You can get it, all
prepared, at a paint store. Wood-alcohol is used to thin it if it gets
too thick. Keep it in a wide-mouth bottle. Paint it on quickly and
evenly with a brush, and do not go over it again when it is partly dry.
Wait until it is thoroughly hard before putting on a second coat. It
should be fairly thin to spread well. Clean your brush in wood-alcohol
before putting it away, and keep the shellac bottle tightly corked. A
small tin can or a teacup is best to hold the shellac when using it.

* * * * *

THINGS A BOY SHOULD KNOW ABOUT ELECTRICITY.

By THOMAS M. ST. JOHN, Met. E.

The book contains 180 pages, and 260 illustrations; it measures
5 x 7-1/2 in., and is bound in cloth.