Alchemical Symbolism in the VMS

[davidjackson]

Fractional distillation was developed by Taddeo Alderotti in the 13th century. The production method was written in code, suggesting that it was being kept secret.

I suspect this is a Wiki-invention. There is no mention of the method being in code in the source quoted by Wikipedia (Holmyard, Eric John (1990). Alchemy. p 53)
The book in question is I Consilia by Taddeo Alderotti. I looked it up and there is no mention of any part of it being in code. A History of Medicine: Medieval medicine (Prioreschi) discusses this in passing, especially with mention of Alderotti's applications of alcohol in medicine (what a waste! ) and again, no mention of a code or cipher, despite transcribing interesting passages.
I admit I haven't read the book in question.