The method is sometimes employed in the assay of gold.
In 1864 a public assay office was established.
The principal buildings are the state capitol, the United States assay office, a Carnegie library, a natatorium, and the Federal building, containing the post office, the United States circuit and district court rooms, and a U.S. land office.
To simplify calculation and to enable the assayer to use the metric system of weights employed in all chemical calculations, the "assay ton" ("A.T."
= 29.166 grammes) has been devised, which bears the same relation to the ton of 2000 lb avoirdupois that one milligram does to the troy ounce; when one assay ton of ore is used, each milligram of gold or silver found represents one ounce to the ton.
As the slag thus formed flows off to the sides of the scorifier, the assay clears and the melted metallic lead forms an "eye" in the middle.
Ores containing much arsenic or sulphur are generally roasted at a low heat and the assay is made on the roasted material.
The fire assay for copper ores was abandoned years ago and the electrolytic method took its place; this in turn is now largely replaced by volumetric methods.
The methods used in the assay for iron are volumetric, and are all based on the property possessed by certain reagents of oxidizing iron from the ferrous to the ferric state.
One gramme of ore is usually taken for assay and treated in a small flask or beaker with 10 cc. of hydrochloric acid.
Various portions, each weighing 10 seers (of 23 5 lb), are selected by test assay so as to ensure the mass being of standard consistence (70% of the pure dry drug and 30% of water), and are thrown into shallow drawers and kneaded together.
Both the St Francois and Jasper ores yield from 70 to 75% of metal in final product, and assay even higher.
Sefstrom's blast furnace, used in Sweden for the assay of iron ores, is a convenient form of portable furnace applied to melting in crucibles.
In 1859 the mines were worked only for their gold; the ignorant miners threw away the " black stuff " which was really valuable silver ore with an assay value four times as great as that of their ores of gold; and when this was discovered there came a period of unprecedented silver production.
The metals he produced are said to have proved genuine on assay; when, however, in the following year he was challenged to repeat the experiments he was unable to do so and committed suicide.
A third addition becomes necessary to remove the rest of the silver, when the lead will assay only o I oz.
The principal officers of the Mint were the master, who manufactured the coin under a contract, the warden or paymaster who acted on behalf of the Crown, the assay master (also a king's officer) who was responsible for the fineness of the coin, the cuneator or superintendent of the engravers of the dies, and the moneyer.
Pieces are cut out for assay, and the bars are then ready for rolling.
There is a United States assay office, established as a branch mint in 1837, during the days of North Carolina's great importance as a gold producing state, and closed from 1861 to 1869.
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.
Alwar was the first native state to accept a currency struck at the Calcutta mint, of the same weight and assay as the imperial rupee, with the head of the British sovereign on the obverse.
The goldsmiths had the assay of metals, the fishmongers the oversight of fish, the vintners of the tasting of wine, &c. The companies enforced their regulations on their members by force.
The .amount of ore taken for assay is generally one-half "A.T.," but in very low-grade ores one, two, and sometimes even four "A.T.s" are used.
The "dry" or fire assay for lead is largely used for the valuation of lead ores, although it is being gradually replaced by volumetric methods.
There are several public assay offices in Italy for silk; the first in the world was established in Turin in 1750.
Varrentrapp pointed out that " cornets " from the assay of gold may retain gas if they are not strongly heated.
The receipt of bullion and the delivery of coin from the Mint is under the charge of the chief clerk, the manufacture of coin is in the hands of the superintendent of the operative department, and the valuation of the bullion by assay, and matters relating to the fineness of the coin are entrusted to the chemist and assayer.
Helena is delightfully situated with Mt Helena as a background in the hollow of the Prickly Pear valley, a rich agricultural region surrounded by rolling hills and lofty mountains, and contains many fine buildings, including the state capitol, county court house, the Montana club house, high school, the cathedral of St Helena, a federal building, and the United States assay office.
The assay of an ore for gold or silver consists of two operations.