We know that the 40% solution of formaldehyde is known as formalin. It also contains 8% methanol and 52% water. The chemical formula is H-CHO.

Formalin is a strong disinfectant, tissue hardener, germicide, and antiseptic in nature. It's used for preserving biological and anatomical specimens. In biological preservation, it may be worked by bonding with proteins and DNA.

If you clarify the mechanism of formalin in preservation, please describe it shortly.