Home › Soldering and the Blow-pipe › Soldering and the Blow-pipe

Soldering and the Blow-pipe

Then arises the question of soldering. These duplicate pieces, struck with a punch, and made of an equal height by being snipped round their edges with shears, and rubbed down on a stone, must now be united by solder-not mere tin or pewter, but what is technically known as hard solder, i.e., a metal only so far inferior by the addition of alloy to the metal it is to unite, that it is fusible at a somewhat lower degree of heat. But to solder in this way requires tools and appliances of a more delicate nature than we have as yet had to deal with. The preparation of solder itself, with its careful and minute proportioning of alloy, and its no less careful fusion-its thinning into plate, and its reduction by some means, by shears or by file, into small particles for use-requires considerable skill and indispensable tools. Then it is impossible to solder without some species of flux, to prevent the oxidation of the two surfaces to be united, during the process. What flux had the Egyptians or the Assyrians? It is a fact that in many parts of the East Indies to this day the native jewelry, although admirable in many points of execution, is not soldered together, but dovetailed, in a manner of speaking, by a series of minute "spitzens." The fineness of the gold employed admits of this process, and the work does not depend for its strength upon its connected parts. The setting of their gems is invariably effected in this way, and with a little force may be lifted off bodily.

Borax is the immemorial flux of the jeweler all over the world, and it is not at all improbable that the Egyptians possessed this valuable medium; especially as, although now an artificial compound of its element, boracic acid and soda, manufactured to meet the demands of commerce, it is found, and was to be found doubtless in that remote time, as a natural production. But given the borax, the solder, the shears, or the file, we still require the charcoal, or some equivalent for it; and what is more, we still require the blow-pipe. His inflated pig-skin would not serve the Assyrian here; something more manageable was necessary-something which possessed both force and precision. It is held by scholars that Pliny (the younger) speaks of borax under the title of chrysocolla, and it is not at all unreasonable to suppose that borax, under this or some other name, was known at a much earlier date than his time. If the Egyptians had not discovered charcoal-and it is very possible they had, considering their necessarily constant use of wood-it would not be difficult to find some light porous stone to answer its purpose;* and the origin of the blow-pipe is so involved in obscurity, that there is scarcely any date too early to fix for its discovery. Moreover, although the blow-pipe of the modern chemist is a very scientific implement, it must be remembered that the jeweler's blow-pipe to this day is simply a piece of bent tubing, smaller at one end than the other. It is at least certain, then, that to solder, the ancients must have possessed some knowledge of alloy, and had for tools the blow-pipe, shears, or files, charcoal, or some analogous non-conductive substance, and must have known the valuable uses of borax as a flux.

This question of alloys is of more consequence than may at first sight appear; for, as a rule, the gold used in these ancient ornaments was in nearly a pure state; and it is not unreasonable to suppose that a knowledge of the ready fusion of certain other metals therewith might have tempted the workmen of antiquity to deteriorate the precious metal, as is systematically done in modern times. The universal use of fine gold suggests also one other solution of the solder difficulty: it is that fine gold, and fine gold alone, may, by the help of a flux, be "sweated," or brazed together instead of soldered; but it is a careful process, and can only be done with heavy pieces of work. It is true there are some examples of framework for * Lava is an excellent substitute, but not likely to be found among the sands of Egypt. inlaying in the cases of the British Museum which have a suspicious aspect, scarcely compatible with purity of material, but they are the exception to the rule; and, on the other hand, it is certain that many legitimate uses, of a less pure but harder gold, were altogether unknown. Thus, there are no joints to earrings, or spring fastenings to any of the ancient ornaments. The earloops are simply the attenuated ends of fine gold wires, which, once passed through the ear, were bent round till they held in their places, to be again straightened, should the earring require to be removed a thing, it may be presumed, not often done. The bracelets, again, are permanent ornaments, and could scarcely have been removed without the aid of the jeweler.