[251] Modern "shell gold" is practically the same thing as the fluid gold of the mediaeval illuminators, except that it is not made with the pure, unalloyed metal. [252] The following are the most useful and easily accessible books on the technical processes of the illuminator; Theophilus, _Schedula diversarum Artium_, Hendrie's edition with a translation, London, 1847; Cennino Cennini, _Trattato della pittura_, 1437, edited, with a translation, by Mrs Merrifield, London, 1844; and a large and valuable collection of early manuscripts on the same subject, edited and translated by Mrs Merrifield under the title of _Original Treatises on the Arts of Painting_, 2 Vols., London, 1849. [253] See page 144. [254] That is to say, it looks as if the whole substance, mordant and all, were one solid mass of gold, nearly as thick as a modern half-sovereign; see Theophilus, I. 24 and 25. [255] So when William Torell was about to gild the bronze effigy of Queen Eleanor in Westminster Abbey he procured a large number of gold florins from Lucca. [256] Not even the smallest admixture of alloy was permitted in the gold coinages of the Middle Ages. Dante (_Inf._ XXX. 73) mentions the coiner Maestro Adamo who had been burnt at Romena in 1280 for issuing florins which had scarcely more alloy than a modern sovereign. [257] The gold penny of Henry III. and the florin and its parts of Edward III. were only struck as patterns. The gold noble was first issued in 1341; its value was 6_s._ 8_d._ or half a _mark_. So many nobles were destroyed to make gold leaf for illuminating, and for other purposes, that an Act was passed prohibiting, under severe penalties, the use of the gold coinage for any except monetary purposes. [258] In the same way the gold leaf used by the Greeks was comparatively thick. The famous Erechtheum inscription of 404 B.C. gives one drachma as the cost of each leaf ([Greek: petalon]) used for gilding the marble enrichments; see _Cor. Ins. Att._ I. 324, fragment C, col. ii. lines 35 and 42. Eighteen-pence will now buy 100 leaves of gold. [259] The best account of the way to make the mordant was given about 1398 by a Lombard illuminator called Johannes Archerius; see Mrs Merrifield's interesting collection of _Treatises on Painting_, Vol. I. page 259 seq. [260] See Theophilus, I. 25. [261] See Mrs Merrifield, _op. cit._ Vol. I. p. 154.