156 SOLDER SOLDER (Lat. tolidui, solid), a metal or alloy used for joining together different pieces of metal, whether of the same or of different kinds. Soldiers are divided into hard and soft. The soft solders may be used for joining all kinds of metals, but usually those having low mcltinir points. The hard solders are better adapted for the less fusible metals, especially where strength is required. Practically the solder must be more fusible than either of the metals to be united, but the more nearly these points coincide the stronger will be the union. Gold in the form of leaf or fine shreds is used for soldering platinum vessels ; it may be slightly alloyed with copper. Silver is con- sidered the best solder for German silver. Copper in shreds is often used for iron when welding is not permissible, sometimes slightly alloyed with zinc. Soft solders have tin for a basis, generally alloyed with lead. Those con- taining much lead are sometimes ranked with hard solders. Pewter may bo used for a sol- der, and by the addition of bismuth, antimony, or cadmium its fusing point may be lowered so that it can be used as a solder for pewter. The following are some of the more important sol- ders. For gold: gold (18 carats) 66-6, silver 16-7, copper 16'7. A good gold solder for gen- eral purposes is 100 parts of gold, 40 of silver, and 30 of copper (Makins). For silver : silver <)G-6, copper 30, brass 3'4; or silver 65, copper 24, zinc 11. It is better to add the metals separately than to use brass, which may have an uncertain composition. Pewterer's solder: coarse tin 3, lead 4, bismuth 2 ; fine tin 2, lead 1, bismuth 1. Plumber's solder : tin 1, lead 3; a finer kind has the same composition as fine pewterer's solder. Hard spelter solder, used for soldering copper, is made of copper I' 1 ., /me 12. Soft spelter solder, for brass, is made of equal parts of copper and zinc. Fluxes are used to preserve the cleanness of the sur- faces of the metals and free them from oxide while the operation of soldering is going on. The solder is applied in various ways. The surfaces, sometimes previously cleaned with a file or with muriatic acid or an acid solution of chloride of zinc, are brought together, and the solder in strips or grains laid on. Then a flux composed of borax or sal ammoniac, some- times mixed with a little common rosin, is ap- plied, and the parts are heated with a blowpipe or a stream of intensely heated air. But it is more common to use a soldering iron, an in- strument consisting of a heavy square, pyra- midal, or conical piece of copper, riveted in a fork of wrought iron, to which a wooden handle is attached. This " iron," being heated above the fusing point of the solder, is applied to it, and a few adhering drops of the melted Hoy are carried to the parts to be joined, which are then held in position until the sol- der hardens. Aluminum cannot be soldered m the ordinary way, but must first be tinned. A good general solder for aluminum is com- posed of zinc 90, aluminum 6, copper 4. SOLE SOLE (solea, Cuv.), a genus of soft-rayed flat fishes of the family pleuronectidce. (See FLOUNDER.) The genus has the jaws concealed under the scaly skin, the upper rounded and longest; the eyes are both on the right side, small, the lower behind the upper and almost at the angle'of the mouth; the mouth is curved, and turned almost wholly to the left side, and the fine and villif orm teeth are nearly all on this side ; the snout is in advance of the mouth; the lateral line straight; branchial openings below the small pectorals; dorsal and anal very long, often confluent with the caudal ; no air bladder, and no pancreatic cseca, and the intestine long and often doubled ; the blind side is sometimes furnished with shred-like villi. The common sole (S. vulgaris, Cuv.) has the body more elongated than in most flat fishes, with a blunt and rounded muzzle ; the length is from 10 to 20 in., and the color uniform dark brown above and white below, the pectorals tipped with black. It inhabits the sandy shores of Great Britain, keeping near the bot- tom, feeding on the spawn and fry of other fishes and on shell fish ; it is found from the seas of Scandinavia to the Mediterranean. It is one of the best and most delicate fishes for the table, and is caught in immense numbers by trawl nets ; the flesh is white and firm, and is in good condition all the year 'except in February and March, when they are spawning.
- Some are found reversed, or with the eyes and
colored surface on the left side, and a few are dark and rough on both sides. In the genus achirus (Lac.) there are no pectorals ; species Common Sole (Solea vulgaris). are found in the Indian seas, with the upper parts marbled with brown and lighter. The New York sole (A. mollis, Mitch.) is 6 to 8 in. long, dark brown, marked transversely with
