The Codex Purpureus Petropolitanus, a Greek manuscript of the Gospels, was written in the 6th century. It gets its name from the fact that it is written on purple parchment. This was made by treating parchment with dye probably derived from the glands of sea snails.
It was costly and time-consuming to produce such parchment and purple is traditionally associated with emperors. This suggests that the manuscript was made for someone connected to the imperial court.
Silver and gold inks were used to write the letters, although the silver has now oxidized to black.
The manuscript was divided and dispersed at some point in the Middle Ages. Most of the leaves are now in St Petersburg, while other leaves are scattered across Europe, with one in New York.
The British Library holds four leaves, containing extracts from the Gospels of Matthew and John. They were acquired by Sir Robert Cotton (1571-1631), probably somewhere on the continent. Cotton’s vast collection of manuscripts was augmented by his son, Sir Thomas Cotton (1594-1662), and grandson, Sir John Cotton (1621-1702), who bequeathed the collection to the nation. The Cotton library subsequently formed one of the foundation collections of the British Museum in 1753.