M. Járó - L. Költő szerk.: Archaeometrical research in Hungary (Budapest, 1988)
Analysis - ÓVÁRI Ferenc: On the metrology of antoniniani originating in the 3rd century
ÓVÁRI Ferenc* ON THE METROLOGY OF ANTONINIANI ORIGINATING IN THE 3rd CENTRUY Abstract — By means'of mathematical methods it is demonstrated from the weight data of more than 9000 antoniniani compiled from the descriptions of finds and collections, how the weight of silver coins decreased in the period from Gordianus III to Aemilianus, i. e. in the course of 15 years. Also the decrease in the average silver sontent of the coins is demonstrated on the basis of chemical analysis of 402 antoniniani. The weight distribution curves of the coins of each emperor are presented. Apart from West's basic article [1], publications dealing with mass data of Roman coins can be found more and more frequently in the numismatic literature. The individual mass of all coins is generally given in recent publications concerning the description of hoards [2—6] in contrast to the previous practice where only the total mass, the number and the average mass of coins were reported [7-8]. Besides other data the individual mass of all coins must be presented in a detailed and accurate description of a hoard according to generally accepted opinion. This is indispensable for a later identification or another investigation. It is well known that the mass and the silver content of antoniniani tend to decrease monotonously from the age of Caracalla. Essentially this fact was strengthened by Le Gentillhomme's publication in 1962 [9] where the mass and the silver content of about 670 coins of the period from Caracalla to Tetricus were given. Other, more detailed determinations are not given by this author. More detailed data are given by Walker [17] about the mass and silver content of 4920 coins from Augusta to Aemilian. The aim of the present study is to investigate the tendency indicated above with a larger collection of data and during a shorter period. As in our earlier publication [10] this period is the interval of 238—253 and the motivation is the same. In this gravimetric analysis some known applied mathematical methods were used and other aspects were introduced which were not investigated before. The descriptions of three comparatively large hoards of Smyrna [2], of Singidunum [3] and of Tuhn [4] are used. Other data are also used, denoted as "other" , from smaller hoards, parts of hoards and mass data from auction leaflets [6—9,11,12]. The masses of about 5000 coins are known from these sources in the interval of 15 years from Gordian to Aemilian and these are analysed by exact methods. An important question concerns the condition of coins for these mass data. The condition is reported only in commercial catalogues and in the hoard of Singidunum. The coins became worn during usage and therefore their mass could have decreased. The mass of coins could be decreased by another effect too, viz, corrosion. The coins interacted chemically with some components of soil, and oxides, basic oxides, carbonates, etc. had formed in the course of centuries. Loss of mass could originate from cleaning off the corrosion products. The copper content of silver-copper alloys could be transported by diffusion from the surface layer of coins and could selectively be corroded because of its negative standard potential. * Veszprém University of Chemical Engineering H-8201 Veszprém, P.O.B. 158
