Isaac Newton is an iconic figure in the history of science but he had a mysterious side that remained hidden and unknown until the 1930s---he wrote more than 125 manuscripts on alchemy, comprising over 2300 pages and a million words. Alchemy was equated with sorcery and charlatanism over many centuries, so the academic world was surprised to learn of Newton's consuming interest and tended to ignore it until very recently. Our project is creating a scholarly online edition of Newton's alchemical manuscripts. The goal is to provide accurate transcriptions of the originals in TEI/XML documents with Unicode encodings. Alchemists used large numbers of special symbols in their cryptic literature to stand for substances, principles, processes, and devices. Newton's use of those symbols presented us with many unexpected challenges. We'll discuss those challenges and describe our use of font editors and symbol generators and XSL to create and serve the symbols, our use of XTF to make them searchable, and our work with the Unicode Consortium to create a new block of code points devoted to these historical alchemical symbols.