Without some hints on soldering, this chapter would not be complete. It is a very useful qualification for boys; if they aim at being "handy boys," they will most likely become "handy men."

Suppose in the first case a saucepan or a kettle leaks, it has to be sent to the tinman's, or ironmonger's; and the job being so insignificant and trifling, is laid aside for others of more importance, yet it is wanted at home, and the delay in its return onuses a lot of worry and annoyance. The next case that occurs, you try and cute it yourself.

Tools for soldering should always be kept at hand A cheap set, with a bit of solder, can be bought for sixpence.

The saucepan must first of all be well scoured with a strong solution of soda and water; this removes all grease, then scrape the hole quite clean. If the hole is only a small one, a little drop of solder will perhaps be sufficient. This you can put on after moistening the spot with what the trade call "killed spirits." This substance is made by dropping strips of zinc into hydrochloric acid, diluted with equal parts of water, till no more zinc is dissolved. This substance acts as a flux. Now heat the soldering-iron in a clear fire (see that it is clear); then rub it on a piece of sal-ammoniac, or some powdered resin, then on to the solder. Apply this to the small hole in the saucepan; it will soon cool and harden. If, however, the hole is too large for this, the best way is to put a piece of tin over it. Well clean all round the hole by scraping, then moisten it all round with killed spirits, and spread on the solder according to the plan already mentioned. Cover it over with a little powdered resin; melt the solder by the soldering-iron heated up afresh, then put on the patch of clean tin. Press it into close contact; the solder will harden. If a very large hole occurs, it will be better to put in a new bottom altogether. This is easily accomplished by cutting out a piece of block-tin, and turning up the edge. Well clean the parts to be joined, and proceed as already directed.

Compo-tubing, such as is used in gas-pipes, may be joined by simply covering the parts with a little powdered resin, and cutting a strip of thin soft solder, and putting on to the resin. The soldering-iron in this case must not be used too hot.

But suppose a water-pipe bursts, as it does sometimes in sharp, frosty weather. You must cut the portion of pipe containing the hole completely out; this you can do with an old saw, cutting the edges off quite square. Then a piece of new pipe must be taken, and the lower piece of old pipe opened out to receive the lower end of the new piece. This you can do by driving in a peg with a mallet - plumbers use boxwood turnpins for the purpose. Now open the upper end of the new piece in the same manner for the lower end of the old pipe to go into. Next take your knife and scrape quite clean the surfaces to be joined. Put the pipes together; this will leave a circular hollow around each pipe. Into these sprinkle some powdered resin, then pour in some melted solder, and pass round the edges the point of the heated iron. Do this till you are sure the solder and lead are melted together. A neat outer joint requires much experience to make, so we must leave that to a professional plumber. We have given you enough directions to secure the joint, and avoid the annoyance of having to wait for plumbers, who are all busy at "pipe-bursting time."

In your practical science work it often happens that you want to join together flat surfaces of copper-band, and join up copper wires; and as we have frequently required to make platinum electrodes, these must have our consideration next. As the platinum electrode is the simplest, we will take that first. If you require a pair, let them be cut off the same size from strip of platinum foil.

Now take a short length of platinum wire for each, and with a metal pin make two holes through the foil in a line where the joint has to be made. Pass the wire through these holes. Hold this part in a blow-pipe flame till it is white hot, then put it quickly on an iron plate, and give it a smart blow with the hammer. Have all things ready for this, so that the blow is struck before the metal has had time to cool. A weld between the wire and the foil will then have been formed. This is more effective and lasting than any soldering.

In soldering copper surfaces, either sheet or wire, let them be thoroughly clean. The flux used is sal-ammoniac and powdered resin. Many mix the powders together, and apply them at the same time. Some recommend a piece of cane split up into filaments, for brushing in a strong solution of sal-ammoniac, and then sprinkling in the resin. We think, however, you will prefer the former plan.

The next thing is to get the soldering-iron the right temperature - for if not hot enough to melt the solder, it must be put into the fire again; and if too hot, the tinned surface on its face will be burned off, and the solder will not stick. Should this be the case, you must re-tin the soldering-iron, then you proceed as we have directed already. The sheets of copper and the wires must be held together till the solder is hard enough to hold them of itself. If you require to loosen any parts soldered together, it is better to do so by a lamp-flame; you can get the parts heated to a higher temperature by that means than by the iron.

To re-tin the soldering iron, you must heat the copper bit in a clear fire, nearly to red-heat; put it in a vice, edge upwards, and file it to a clean metallic surface. Then rub it over with a piece of sal-ammoniac, and drop on a small bit of solder, or rub on it a bar of solder. The surface of the soldering-iron will then be covered again with tin, and will be ready for use.

With these methods, which are the only ones you are likely to require, we will conclude our chapter on metal-work.

Many books on the separate departments of metal-work are in existence, and which are exceedingly useful in giving you hints for work. Best of all, if you wish to get a better practical knowledge of the subject, join a good workshop. Many workshops in connection with our technical schools are now open, giving excellent chances to amateurs and others.