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.
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.
See page [144].
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.
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.