52:6 · A sign for aqua fortis, or nitric acid, used in alchemy and early chemistry. Here we can decipher the alchemical sign for the element of water, , with an added F for "fortis", Latin for strong.
    Aqua fortis, or the strong water, was the only acid the alchemists knew that could dissolve silver, but not gold, and accordingly was used to distinguish between the two elements. See also the next entry.
    When platinum was discovered alchemy already had given way to modern chemistry, but nitric acid cannot dissolve platinum either.
    Nitric acid was also drawn , , and otherwise.