I used approximately 58g of dried, and partially burnt rose petals in this experiment. These were calcined to grayness, and then extracted with vinegar.

After filtration I was left with a richly colored solution (no doubt due to organic molecules). This was titrated with sodium hydroxide, and left to settle. It was washed with distilled water a number of times (four, or five times) to remove most water soluble salts, and any remaining organic molecules. The result was a clear solution with an off-white precipitate.

I have noticed that over the course of a few weeks the precipitate has darkened noticeably. I do not know how to explain this except by believing that the matter is undergoing putrefaction. Very interesting indeed.