Astronomy. Regulus, a first magnitude star in the constellation Leo.
Metallurgy.
the metallic mass that forms beneath the slag at the bottom of the crucible or furnace in smelting ores.
an impure intermediate product obtained in smelting ores.
First recorded in 1550–60; from Latin rēgulus literally, “little king” (diminutive of rēx ); in early chemistry, “antimony,” so called because it readily combines with gold (the king of metals); see -ule
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In any event, if the powder was introduced into the molten bullion, the effect would be to form some silver sulphides in a regulus of different composition depending upon the varied ingredients of different compounds.
From De Re Metallica, Translated from the First Latin Edition of 1556 by Agricola, Georgius
The regulus of antimony is of a silvery white colour, of a scaly texture, very brittle, and melts soon after ignition.
From Heads of Lectures on a Course of Experimental Philosophy: Particularly Including Chemistry by Priestley, Joseph
It is probable, however, that the sulphur in the regulus would attack the iron and make it black.
From De Re Metallica, Translated from the First Latin Edition of 1556 by Agricola, Georgius
When gold is parted from sixty-six librae of silver, the silver, copper, and sulphur regulus weighs one hundred and thirty-two librae.
From De Re Metallica, Translated from the First Latin Edition of 1556 by Agricola, Georgius
Heated in close vessels, this metal rises without decomposition, being the most volatile of all the metals except the regulus of arsenic.
From Heads of Lectures on a Course of Experimental Philosophy: Particularly Including Chemistry by Priestley, Joseph
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