I'm very fond of these diddy little inkwells, and I have several kicking around the place. Today, I found a random one in the fridge (I keep inks in the fridge, cos they can grow mould if you don't). What's in it?
There are only two sorts of ink the mystery bottle can contain, at present, cos I only have two kinds of black ink in the house. One of them is kosher, and I can use it on the Torah, and one of them isn't, and I can't use it on the Torah, and if I do the Torah will be pasul. Invalid. Bad news. I could taste it and work out what it is, but ink tastes vile
, sofer's ink more so, so I'd rather not.
Science to the rescue! Colour chromatography.
By way of illustrating the method, first we'll compare two known inks.
Fig 1a: Left: sofer's ink. Right: Brand X ink
Fig 1b: Left: sofer's ink. Right: Brand X ink
You take two strips of kitchen roll, and put a blob of ink near the end of each. Properly, you hang the strips vertically because the reason it works has to do partly with gravity, but for this kind of thing you can just drape them over a plate and it works fine.
Then you dip the ends in water, and see what happens!
The different pigments move through the paper at different rates, and separate out, so you can get an idea of what's in the ink. The sofer's ink mostly stays black, with a sort of pink tinge round the edges, and Brand X goes all kinds of colours - yellow at the top, blue at the bottom. It also spreads much further, because it's more water-soluble (sofer's ink binds chemically to natural fibres) it looks like there's just more of it in the picture, but I used the same amounts - Brand X spreads even before you wet it, that's all).
So, now we can find out what the mystery ink is.
Fig 2a: Left: sofer's ink. Right: Mystery ink
Fig 2b: Left: sofer's ink. Right: Mystery ink
Two blobs on dry kitchen paper, draped over a plate, same as before. Wet the ends...
...and we see no blue, no yellow, only the pink tinge and the limited spread, just like the one we know for sure is sofer's ink. So it must be sofer's ink.
Hooray for science!