a piece of impiety

So the heroine of my work in progress, The Duke Who Never Forgets, owns an ink factory.  She's an ink chemist and owns this company that brews and manufactures ink according to formulae of her devising. As a result, I've been reading about ink.  My best resource so far has been 40 Centuries of Ink by David Nunes Carvalho (thank you, Google Books!), which is brimming over with everything I could possibly need - like a zillion recipes for permanent black ink, for example.  I'm thinking I might have to do a bit of brewing just for authenticity's sake.

It's also full of odd little legends, like the one that follows:

"A strange old woman came once to Tarquinius Superbus with nine books, which, she said, were the oracles of the Sybils, and proffered to sell them. But the king making some scruple about the price, she went away and burnt three of them; and returning with the six, asked the same sum as before. Tarquin only laughed at the humour; upon which the old woman left him once more; and after she had burnt three others, came again with them that were left, but still kept to her old terms.

The king now began to wonder at her obstinacy, and thinking there might be something more than ordinary in the business, sent for the augars [sic] (soothsayers) to consult what was to be done.  They, when their divinations were performed, soon acquainted him with what a piece of impiety he had been guilty of, by refusing a treasure sent to him from heaven, and commanded him to give whatever she demanded for the books that remained.  The woman received her money, and delivered the writings."