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m:metal

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Metal

The technical name of a mixture of metals properly so called, with which types and stereotype plates are cast.

In speaking of type metal, I shall first give Moxon's description of making it, which is curious; and then some interesting observations on the same subject by M. Sage, from the Journal de Physique.

Moxon says — “What the metal founders make printing letters of, is lead hardened with iron: thus, they choose stub nails for the best iron to melt, as well because they are assured stub nails are made of good, soft, and tough iron, as because they (being in small pieces of iron) will melt the sooner.

“To make the iron run, they mingle an equal weight of antimony (beaten in an iron mortar into small pieces) and stub nails together. And preparing so many earthen forty or fifty pounds melting pots (made for that purpose to endure the fire) as they intend to use: they charge these pots with the mingled iron and antimony as full as they will hold.

“Every time they melt metal, they build a new furnace to melt it in: this furnace is called an open furnace; because the air blows in through all its sides to fan the fire; they make it of bricks in a broad open place, as well because the air may have free access to all its sides, as that the vapours of the antimony (which are obnoxious) may the less offend those that officiate at the making of the metal: and also because the violent fire made in the furnace should not endanger the firing any adjacent houses.

“They consider, before they make the furnace, how many pots of metal they intend to melt, and make the furnace sizeable to that number: we will suppose five pots. Therefore they first make a circle on the ground capable to hold these five pots, and wider yet by three or four inches round about; then within this circle they lay a course of bricks close to one another to fill the plain of that platform, with their broad or flat sides downwards, and their ends all one way, and on this course of bricks they lay another course of bricks as before, only the lengths of this course of bricks lies athwart the breadths of the other course of bricks; then they lay a third course of bricks with their lengths cross the breadth of the second course of bricks.

“Having thus raised a platform, they place these five pots in the middle of it close to one another, and then on the foundation or platform raise the furnace round about by laying the bricks of the first lay end to end and flat, close to one another; on the second lay, they place the middle of a brick over a joint (as the bricklayers call it) that is, where the ends of two bricks join together, and so again lay bricks end to end till they trim round the platform. Then they lay a third lay of bricks, covering the joints of the second lay of bricks as before: so is the foundation finished.

“Then they raise the walls to the furnace on this foundation; but do not lay the ends of their bricks close together, but lay the ends of each brick about three inches off each other, to serve for wind holes till they trim round about: then they lay another lay of bricks, leaving other such wind holes over the middle of the last lay of bricks, and so trim as they work round, either with half bricks or bats, that the wind holes of the last lay may be covered: and in this manner and order they lay so many lays, till the walls of the furnace be raised about three bricks higher than the mouths of the melting pots, still observing to leave such wind holes over the middle of every brick that lies under each lay.

“Then they fill the sides of the furnace round about the melting pots, and over them, with charcoal, and fire it at several wind holes in the bottom, till it burn up and all over the furnace, which a moderate wind in about an hour's time will do: and about half an hour's time after, they lay their ears near the ground and listen to hear a bubbling in the pots; and this they do so often till they do hear it. When they hear this bubbling, they conclude the iron is melted: but yet they will let it stand, perhaps half an hour longer or more, according as they guess the fire to be hotter or cooler, that they may be the more assured it is all thoroughly melted. And when it is melted, the melting pot will not be a quarter full.

“And in or against that time, they make another small furnace close to the first, (to set an iron pot in, in which they melt lead,) on that side from whence the wind blows; because the person that lades the lead out of the iron pot (as shall be shewed by and by) may be the less annoyed with the fumes of the metal, in both furnaces. This furnace is made of three or four course of bricks open to the windward, and wide enough to contain the designed iron pot, with room between it and the sides to hold a convenient quantity of charcoal under it, and about it.

“Into this iron pot they put for every three pound of iron, about five and twenty pounds of lead. And, setting fire to the coals in this little furnace, they melt and heat this lead red hot.

“Hitherto a man (nay, a boy) might officiate at all this work; but now comes labour would make Hercules sweat. Now they fall to pulling down so much of the side of the open furnace as stands above the mouth of that melting pot next the iron pot, and having a thick strong iron ladle, whose handle is about two yards long, and the ladle big enough to hold about ten pounds of lead, and this ladle red hot that it chill not the metal; they now, I say, with this ladle, fall to clearing this first melting pot of all the coals or filth that lie on the top of the melted metal; while another man at the same time stands provided with a long, strong, round iron stirring poot, the handle of which stirring poot is also about two yards long or more, and the poot itself almost twice the length of the depth of the melting pot: this poot is nothing but a piece of the same iron turned to a square with, the handle: and this poot is also in a readiness heated red hot.

“Now one man with the ladle lades the lead out of the iron pot into the melting pot, while the other man with the poot stirs and labours the lead and metal in the melting pot together, till they, think the lead and metal in the melting pot be well incorporated: and thus they continue lading and stirring till they have near filled the melting pot.

“Then they go to another next melting pot, and successively to all, and lade and stir lead into them as they did into the first. Which done, the metal is made: and they pull down the walls of the open furnace, and take away the fire that the metal may cool in the pots.

“Now (according to custom) is half a pint of sack mingled with sallad oil, provided for each workman to drink; intended for an antidote against the poisonous fumes of the antimony, and to restore the spirits that so violent a fire and hard labour may have exhausted. — Moxon.

Smith, who published his Printer's Grammar about seventy years after the appearance of Moxon's work, says, “In Germany they use more than three ingredients to their metal, which is there made of steel, iron, copper, brass, tin, and lead; all which they incorporate with each other by means of antimony. This metal, if duly prepared, does not bend, but breaks like glass; it is harder than tin and lead, something softer than copper, and melts sooner than lead. This account I have of Mr. Struke, a printer at Lubec.”

“Observations on the Metallic Mixture made use of for casting Letters, or Characters, for Printing. By M. Sage. From the Journal de Physique.

“Lead and regulus of antimony, melted together in various proportions, form the metal used by letter founders, for casting their different types or characters. When I say that these metals are used in various proportions, I mean, that more or less of the regulus of antimony is mixed with the lead, according to the degree of hardness the types are required to possess. In general, eighty pounds of lead are added to twenty pounds of regulus of antimony, already melted: but, for the small characters, in which a greater degree of hardness is required, seventy-five pounds of lead are used to twenty-five pounds of regulus of antimony; and, for large ones, eighty-five pounds of lead, and fifteen pounds of regulus of antimony.

“These two substances, though of very different specific gravities [Lead, 11.35. — Antimony 6.70. W. S.], remain perfectly combined, and do not separate from each other by fusion, unless the fire made use of is so strong as to burn and volatilize them; in that case, the antimony begins to exhale.

“Letter founders should take care to employ only the purest regulus of antimony, or that which is the most free from sulphur; for, when it contains any of that substance, it acts upon the lead, in the course of time, and forms with it a kind of galena, which acquires a black colour. The letters cast with a mixed metal of that kind, instead of preserving their shining and polished appearance, become dull, and as it were cracked, forming also a sort of efflorescence. When this spontaneous decomposition takes place, the letters become brittle, and lose their form. Of this I have been convinced, by having analyzed a mixture of this kind, with which M. Anisson had cast some Arabic characters.

“Having exposed some of the letters, made with this bad metal, to a violent fire, the sulphur it contained burnt, and exhaled, in the form of vitriolic acid. Having then poured the metal remaining in the crucible into an ingot, it acquired a white brilliant colour like silver; which colour did not become sensibly changed, by being left, for the space of six months, in a damp place.

“Regulus of antimony is prepared, in the large way, by melting calcined antimony, in a reverberatory furnace, with dried wine lees; from this is obtained the regulus, which is sold in the form of round cakes, on the surface of which are seen figures like the leaves of fern, &c. which figures are produced from the elements of octoëdral crystals. If the regulus, thus prepared, appears more grey in colour than when it is prepared according to Stahl's process, it is because it still retains a portion of sulphur.

“At present, there is not found a sufficient quantity of regulus of antimony in commerce to supply the letter founders. It appears to me that, in the place of regulus of antimony prepared as above, we might substitute that which may he prepared with iron. One-fifth part of iron is sufficient to absorb all the sulphur with which antimony is mineralized. When this mixture is melted, it must be poured into a cone: the sulphuretted iron remains upon the surface of the regulus, and is very easily separated from it.

“This process is less expensive, and produces more regulus, than the process made use of by those who work the mines of antimony.

“Regulus of antimony, as we have seen, gives hardness to lead; but a much greater degree of hardness is produced by adding tin to the mixture. I have analyzed some nails which were proposed to be used in shipbuilding, and found them to contain three parts of tin, two parts of lead, and one part of regulus of antimony. These nails were sufficiently hard to penetrate oak wood, without being blunted; and this metallic mixture is not acted upon by sea water, which very quickly decomposes iron.”

These observations of M. Sage show the utility of iron in the making of type metal by our predecessors, from its combining with the sulphur contained in the antimony.

Stereotype founders vary considerably the proportions of lead and regulus of antimony in making their metal. The hardest metal made, is in the proportion of ten pounds of regulus of antimony to forty pounds of tea lead; but the general proportions are ten pounds of regulus of antimony to sixty pounds of lead, which are said to make a mixture of a good quality.

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