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The unit for \(\textit{Technical Atmosphere}\), symbol: \(at\), is a non-SI unit of pressure equal to one kilogram-force per square centimeter.
The symbol \(at\) clashes with that of the katal (symbol: \(kat\)), the SI unit of catalytic activity; a kilotechnical atmosphere would have the symbol \(kat\), indistinguishable from the symbol for katal.
It also clashes with that of the non-SI unit, the \(attotonne\), but that unit would be more likely be rendered as the equivalent SI unit.
Assay ton (abbreviation \(AT\)) is not a unit of measurement, but a standard quantity used in assaying ores of precious metals; it is \(29 1D6 \,grams\) (short assay ton) or \(32 2D3 \,grams\) (long assay ton),
the amount which bears the same ratio to a milligram as a short or long ton bears to a troy ounce.
In other words, the number of milligrams of a particular metal found in a sample of this size gives the number of troy ounces contained in a short or long ton of ore. |