Not a few of them that practised curious arts (ικανο των τα περιεργα πραξαντων). Considerable number of the performers or exorcists themselves who knew that they were humbugs were led to renounce their evil practices. The word περιεργα (curious) is an old word (περι, εργα) originally a piddler about trifles, a busybody (1 Timothy 5:13), then impertinent and magical things as here. Only two examples in the N.T. It is a technical term for magic as the papyri and inscriptions show. Deissmann (Bible Studies, p. 323) thinks that these books here burned were just like the Magic Papyri now recovered from Egypt.

Burned them in the sight of all (κατεκαιον ενωπιον παντων). Imperfect active of κατακαιω. It probably took a good while to do it, burned them completely (up, we say; down, the Greeks say, perfective use of κατα). These Magical Papyri or slips of parchment with symbols or magical sentences written on them called Εφεσια Γραμματα (Ephesian Letters). These Ephesian Letters were worn as amulets or charms.

They brought them together (συνενεγκαντες). Second aorist active participle of συνφερω. What a glorious conflagration it would be if in every city all the salacious, blasphemous, degrading books, pamphlets, magazines, and papers could be piled together and burned.

They counted (συνεψηφισαν). First aorist active indicative of συνψηφιζω, to reckon together. In LXX (Jeremiah 29:49). Only here in N.T. Συνκαταψηφιζω in Acts 1:26.

Fifty thousand pieces of silver (αργυριου μυριαδας πεντε). Five ten thousand (μυριαδας) pieces of silver. Ephesus was largely Greek and probably the silver pieces were Greek drachmae or the Latin denarius, probably about ten thousand dollars or two thousand English pounds.