ÆS UXORIUM, in Antiquity, a sum paid by bachelors, as a penalty for living single to old age. This tax for not marrying seems to have been first imposed in the year of Rome 350, under the censorship of M. Furius Camillus and M. Posthumus. At the census, or review of the people, each person was asked, Et tu ex anima sententia uxorem habes liberum querendorum causa? He who had no wife was hereupon fined after a certain rate, called æs uxorium.
Æs per et libram was a formula in the Roman law, whereby purchases and sales were ratified. Originally the phrase seems to have been only used in speaking of things sold by weight, or by the scales: but it afterwards was used on other occasions. Hence even in adoptions, as there was a kind of imaginary purchase, the formula thereof expressed, that the person adopted was bought per æs et libram.
Æs Flavum, yellow copper, among the Romans, an appellation given to the coarser kinds of brass.
The ancients had different kinds of brass, as æs candidum, æs Corinthium, denoting probably different metallic alloys or mixtures.
Æs Caldarium, a term used by the German mineralists, for a substance which sometimes occurs to those who work upon cobalt, and is used for making the fine blue colour called smalt.
Æs Ustum, a chemical preparation, made of thin leaves of copper, sulphur, and nitre, placed stratum super stratum in a crucible, and set in a charcoal fire till all the sulphur is consumed; after which, the copper is taken out of the crucible, and reduced to powder. Some quench the leaves of copper in vinegar, and repeat the calcination.—Its principal use is in colouring glass, to which it gives a beautiful tincture. The surgeons use it as a detersive, and some have given it internally; but it is certainly a very dangerous medicine, and should be avoided.