Detective title "death notice"

The reason is this. Because some people paint rice soup or starch on the wallpaper, because primroses contain a lot of iodine. Iodine reacts with starch to turn blue, which is unique in high school chemistry.

This mainly depends on the structure of starch itself. Starch is white amorphous powder, which consists of amylose (accounting for 10-30%) and amylopectin (accounting for 70-90%). Amylose can be dissolved in hot water without paste, while amylopectin is insoluble in water, and it will swell into paste when hot water acts on it. Among them, water-soluble amylose is curved and curled into a spiral shape through intramolecular hydrogen bonds. At this time, when iodine is added, iodine molecules drill into the gaps in the helix and link with amylose through van der Waals force, thus forming a complex. This compound can uniformly absorb other visible light except blue light (wavelength range is 400-750 nm), thus making starch dark blue. This is also the reason why this article mentions the full moon. Starch can adsorb iodine, which makes the wavelength of visible light absorbed by iodine move to the short wavelength direction, thus making it blue.

To sum up, the murderer is directly related to the so-called fortune teller.