4. Parchment is said to have been introduced at Rome not long after its employment by Attalus. Nevertheless, if it had been in constant and ordinary use under the first Emperors, we can hardly suppose that specimens of secular writing would have failed to come down to us. Its increased growth and prevalence about synchronize with the rise of Constantinopolitan influence. It may readily be imagined that vellum (especially that fine sort by praiseworthy custom required for copies of Holy Scripture) could never have been otherwise than scarce and dear. Hence arose, at a very early period of the Christian era, the practice and almost the necessity of erasing ancient writing from skins, in order to make room for works in which the living generation felt more interest, especially when clean vellum failed the scribe towards the end of his task. This process of destruction, however, was seldom so fully carried out, but that the strokes of the elder hand might still be traced, more or less completely, under the more modern writing. Such manuscripts are called _codices rescripti_ or palimpsests (παλίμψηστα(22)), and several of the most precious monuments of sacred learning are of this description. The Codex Ephraemi at Paris contains large fragments both of the Old and New Testament under the later Greek works of St. Ephraem the Syrian: and the Codex Nitriensis, more recently disinterred from a monastery in the Egyptian desert and brought to the British Museum, comprises a portion of St. Luke’s Gospel, nearly obliterated, and covered over by a Syriac treatise of Severus of Antioch against Grammaticus, comparatively of no value whatever. It will be easily believed that the collating or transcribing of palimpsests has cost much toil and patience to those whose loving zeal has led them to the attempt: and after all the true readings will be sometimes (not often) rather uncertain, even though chemical mixtures (of which “the most harmless is probably hydrosulphuret of ammonia”) have recently been applied with much success to restore the faded lines and letters of these venerable records.