Brazing
Soldering with an alloy of copper and zinc. This operation is usually confined to joining copper, zinc, and iron surfaces, and in order to effect a solid junction the surfaces to be united must be made clean and bright. The brazing alloy, after being granulated, must be wetted with ground borax and water and then dried, after which it must be strewn over the gap or crevice, or between the two pieces to be united, which are then exposed to heat until the solder flows between them. The solder may be rendered more fusible by the addition of a little zinc. See SOLDERING; SOLDERS; CAST IRON TO BRAZE.
Breast-hole is the hole in front of the cupola, just back of the spout, at which place the tap-hole is formed. Much of the trouble caused by slag gathering at the tap-hole is attributable to the very careless manner in forming the tap-hole. Sand is used for this purpose without reference to its refractoriness, the consequence being that the intense heat gradually melts it into slag, and it issues from the hole at every tap. If the heated fuel in front is made as level as possible, filling all the spaces with pieces of coke before the sand is introduced, and no more than about three inches of a well-dampened and refractory mixture be rammed therein, much if not all of the trouble from slag at that point will cease. See CUPOLA; SPOUT; SLAG; TAP-HOLE.