"It" is edible black gel-dye to be used in cake decorating!
The nurse who gave it to me is also a cake decorator and while sharing ideas and experiences, she told me of this black dye that she'd found that truly makes your icing black instead of a sickly grey color, as most black dyes do (or you can get it a black color, but by that time, the icing has so much coloring in it that it tastes awful, I've heard.) As I'd shared some rhubarb and recipes with her earlier this year, she said she'd just give me some dye to try. I was pleased with her generosity and was glad to have a cake to try it out on right away!
The following picture is of the baby-shower cake I made last October. I used the same recipe for fondant as I did in my last cake, but to get the dark polka-dots, I had to mix in lots of black dye, plus some blue, red, purple, brown........ to try to get it a nice dark color.
...Now, this is the cake I made the other day, using a small amount of the new black dye:
Well, it's a new day and a new week. There are chokecherries to be picked and cucumbers to be pickled... I'd best be going.