chromatography

what is chromatography basically chromatograpy is a means to an end its used to split up different types of liquids using water and a sample of the liquid at the scene of the crime

from tihe results you could tell maybe which pen was used to write a ransum note then you could look for fingerprints.

.chromatography has been used since around the 19th -20th century and basically means colour writng

Paper chromatography is a technique that involves placing a small dot of sample solution onto a strip of chromatography paper. The paper is placed in a jar containing a shallow layer of solvent and sealed. As the solvent rises through the paper, it meets the sample mixture which starts to travel up the paper with the solvent. This paper is made of cellulose, a polar substance, and the compounds within the mixture travel farther if they are non-polar. More polar substances bond with the cellulose paper more quickly, and therefore do not travel as far.