The introduction of formalin, a formaldehyde solution, as a disinfectant and fixative was an essential improvement in anatomical and histological science. This paper is an outline of the historical use of formalin based on primary source texts and historical studies. We describe how the discovery of acetaldehyde in the 18th century led to the development of formalin as the most common ingredient in embalming fluids in the 20th century and is still used today. Particularly important contributions to this process were made by Justus von Liebig, Alexander Butlerow and August Wilhelm Hofmann in the development of anatomical and histological preparation techniques, and by Ferdinand Blum, Ferdinand Julius Cohn, Frederick C. Kenyon and Victor Wehr in the practical uses of formaldehyde solutions in preservation and fixation of soft tissues. However, formalin is not without its drawbacks and as its toxicity became more understood, method to mitigate its effects were demanded. Eventually safer preparation techniques were developed, including Hagens' plastination and Thiel Embalming Method. These techniques may someday largely replace high-concentration formalin solutions but they both still require at least small quantities of formaldehyde to preserve tissues for study.
Keywords: formaldehyde solution; formalin; history of anatomy; history of histology; scientific preparatory techniques.