A couple of days after making the divine water (https://distillatio.wordpress.com/2013/05/04/making-the-divine-or-sulphur-water/), I tried one method of using it. It’s the same one as Lawrence Principe uses in his book, and indeed I asked him about it a year before the book was published. He said the secret was in the temperature, or words to that effect. I had previously tried it this way but had either left it in too long or made it too hot, or maybe not had a very good quality of ‘water’. It is worth nothing that the Leyden papyrus doesn’t specify how to use this water.
So first I dipped the silver into the liquid when it was cold, and not a lot happened except that over 10 minutes in it, the silver turned slightly yellow, but left for longer and it went black. Whilst black is an alchemical colour, it isn’t the one we want here, at the end of the process.
So I heated the golden liquid until it became more red, although nowhere near boiling. Say about hand hot. A few seconds immersed in it gave this, shown with some untreated silver:
Note the shine of the metal and the apparent depth of colour.
I stuck another sample in for longer, it turned black. I’d killed it! (Silver sulphides are black, but a thin layer of them is, as you can see, gold coloured)
Which is of course a possible aim, since much reference is made to the death of metals and their resurrection in Graeco-Egyptian alchemy.
The next step in the use of this substance would probably be to seal the colour in using some kind of varnish, because now, three weeks later, the colour on the silver has faded to a slight yellow as the sulphides have evaporated or oxidised.
The next step after turning the silver black would be to melt it with other ingredients, but exactly what I am not sure.
The funny thing is that I haven’t found any later mention of this recipe than a 9/10th century Arabic text. I suspect that might be because by that time and after, both in Arabic countries and in Europe, such a superficial colour change was nothing special and had no value, since it did not lead to anything really like gold. Whereas the Egyptian alchemists were more interested in the specific colour change using divine/ sulphurous substances, themselves of important colours and unusual behaviour and so it was of great use to them.