Their general purport is shown in many cases by pictorial figures relating to various objects which appear on them - such as chariots and horses, ingots and metal vases, arms and implements, stores of corn, &c., flocks and herds.
The important exports are gums and resin, fibre, hides, ivory, ostrich feathers, coffee, ghee, livestock, gold ingots from Abyssinia and mother-of-pearl; the shells being found along the coast from Zaila to beyond Berbera.
The great contrast in apparent structure between cooled ingots of Class I.
This method is rarely practised except by the rollers of zinc. A certain amount of refined zinc can be dipped from the furnace; a further amount, nearly free from iron, can be liquated out of the ingots cast from the bottom of the bath in a subsequent slow remelting, and it is sometimes possible to eliminate a zinciferous lead which collects in the sump of the furnace.
As each retort in a furnace is in all essentials a separate crucible, and as the metal from only a few of them goes into a single ingot, there can be no uniformity either in the ingots made from the same furnace during a day's run or in those made from several furnaces treating the same ore.
Much information as to the nature of an alloy can be obtained by placing several small ingots of the same alloy in a furnace which is above the melting-point of the alloy, and allowing the temperature to fall slowly and uniformly.
Yd., are removed monthly, their gold content being from 0.5 to 1 0%, and after folding are melted in reverberatory furnaces to ingots containing 2 to 4% of gold.
The tad is not a coin, the only silver currency, apart from imported dollars, being the ingots of silver known as "sycee"; the only other native currency is the copper "cash."
In general, only old coin, ingots resulting from the melting of coin, and " fine " ingots are received.
Fine gold ingots (the " bar gold " of commerce) are usually about 400 oz.
Fine silver ingots usually weigh from l000 to 1200 oz.
The ingots are valued by weighing and assaying, and a calculation is made as to the amount of copper required for melting with them to produce the standard alloy.
The gods received tithes of the produce of trade and of the field, in kind or in ingots and golden statues, and these tributes, with freewill offerings, erected and maintained the temples.
But, at least in the south, market centres had sprung up, town life was beginning, houses of a better type were perhaps coming into use, and the southern tribes employed a gold coinage and also a currency of iron bars or ingots, attested by Caesar and by surviving examples, which weigh roughly, some two-thirds of a pound, some 21 lb, but mostly I g lb.
Ingots of Chinese silver were sent from Lhasa with a small proportion of gold dust, and an equal weight in mohurs was returned, leaving to the Nepal rajahs, between gold dust and alloy, a good profit.
The shaping processes include the mechanical ones, such as rolling, forging and wire-drawing, and the remelting ones such as the crucible process of melting wrought iron or steel in crucibles and casting it in ingots for the manufacture of the best kinds of tool steel.
To bring them to a temperature suitable for rolling, these ingots must be set in heating or soaking furnaces (§ 125), and this should be done as soon as possible after they are cast, both to lessen the loss of their initial heat, and to make way for the next succeeding lot of ingots, a matter of great importance, because the charges of steel follow each other at such very brief intervals.
Here, as soon as the ingots have so far solidified that they can be lifted without breaking, their moulds are removed and set on an adjoining train of cars, and the ingots are charged directly into the soaking furnace.
In the other movements, all the moulds and ingots of a given charge of steel are grouped as a train, which is moved as a unit by a locomotive.
When the ingots had so far solidified that they could be handled, the moulds were removed and set on the floor to cool, the ingots were set on a car and carried to the soaking furnace, and the moulds were then replaced in the casting pit.
Here each mould and each ingot was handled as a separate unit twice, instead of only once as in the car casting system; the ingots radiated away great quantities of heat in passing naked from the converting mill to the soaking furnaces, and the heat which they and the moulds radiated while in the converting mill was not only wasted, but made this mill, open-doored as it was, so intolerably hot, that the cost of labour there was materially increased.
- Maximum Production of Ingots by a Pair of American Converters.
Then the furnaceman, controlling the decarburization and purification of the molten charge by his examination of test ingots taken from time to time, gradually oxidizes and so removes the foreign elements, and thus brings the metal simultaneously to approximately the composition needed and to a temperature far enough above its present meltingpoint to permit of its being cast into ingots or other castings.
Charges in closed crucibles, and then casting it into ingots or other castings, though in addition the metal while melting may be carburized.
Steel ingots and other steel castings are subject to three kinds of defects so serious as to deserve notice here.
In making armour-plates from steel ingots, as much as 40% of the metal may be rejected as unsound from this cause.
The steel is cast in lots, weighing in some cases as much as 75 tons, in enduring cast iron moulds into very large ingots, which with their initial heat are immediately rolled down by a series of powerful roll trains into their final shape with but slight wear and tear of the moulds and the machinery.
Of these two will be shown here, the Gjers soaking pit for steel ingots, and the Eckman or continuous furnace, as modified by C. H.
(See § 121.) In this form the system is rather inflexible, for if the supply of ingots is delayed the pits grow unduly cool, so that the next ensuing lot of ingots either is not heated hot enough or is delayed too long in soaking.
- The Gjers system is not applicable to small ingots or " billets," 1 because they lack the inner surplus heat of large ingots; indeed, they are now allowed to cool completely.
To charge a lot of them as a whole in a heating furnace, bring them as a whole to rolling temperature, and then withdraw them as a whole for rolling, is very wasteful of heat, because it is only in the first part of the heating that the outside of the ingots is cool enough to abstract thoroughly the heat from the flame.
In the case of the " Lusitania," is so small that it would be wasteful to instal for their manufacture the great and costly rolling mill needed to reduce them from the gigantic ingots from which they must be made, with its succession of decreasing passes, and its mechanism for rotating the piece between passes and for transferring it from pass to pass.
1 Ingots only.
By placing ingots in a furnace and observing which one melted a fair idea of the temperature was obtained.
Bullion, whether in the form of coins, or of bars and ingots stamped, is subject, as a general rule of the London market, not only to weight but to assay, and receives a corresponding value.
" Japan " copper is purple-red in colour, and is formed by casting into ingots, weighing from six ounces to a pound, and rapidly cooling by immersion in water.