The Merck Index is an encyclopedia ofchemicals,drugs andbiologicals with over 10,000monographs on single substances or groups of relatedcompounds^[1] published online by theRoyal Society of Chemistry.^[2]

The first edition of the Merck's Index was published in 1889 by the German chemical companyEmanuel Merck and was primarily used as a sales catalog for Merck's growing list of chemicals it sold.^[2] The American subsidiary was established two years later and continued to publish it. During World War I the US government seized Merck's US operations and made it a separate American "Merck" company that continued to publish the Merck Index.

In 2012 the Merck Index was licensed to theRoyal Society of Chemistry.^[3] An online version of The Merck Index, including historic records and new updates not in the print edition,^[1] is commonly available through research libraries. It also includes an appendix with monographs on organicnamed reactions.

The 15th edition was published in April 2013.

Monographs inThe Merck Index typically contain:^[1]

• aCAS registry number
• synonyms of the substance, such astrivial names andInternational Union of Pure and Applied Chemistry nomenclature
• achemical formula
• molecular weight
• percent composition
• astructural formula
• a description of the substance's appearance
• melting point andboiling point
• solubility insolvents commonly used in the laboratory
• citations to other literature regarding the compound'schemical synthesis
• a therapeutic category, if applicable
• caution and hazard information

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  1st (1889) – first edition released by E. Merck (Germany)
• 2nd (1896) – second edition released by Merck's American subsidiary and added medicines from theUnited States Pharmacopeia andNational Formulary
• 3rd (1907)
• 4th (1930)
• 5th (1940)
• 6th (1952)
• 7th (1960) – first named editor is Merck chemist Paul G. Stecher^[2]
• 8th (1968) – editor Paul G. Stecher
• 9th (1976) – editor Martha Windholz, a Merck chemist
• 10th (1983),ISBN 0-911910-27-1 – editor Martha Windholz. In 1984 the Index became available online as well as printed.
• 11th (1989),ISBN 0-911910-28-X
• 12th (1996),ISBN 0-911910-12-3 – editor Susan Budavari, a Merck chemist
• 13th (2001),ISBN 0-911910-13-1 – editor Maryadele O'Neil, senior editor at Merck
• 14th (2006),ISBN 978-0-911910-00-1 – editor Maryadele O'Neil
• 15th (2013),ISBN 978-1-84973670-1 – editor Maryadele O'Neil; first edition under the Royal Society of Chemistry^[3]

• List of academic databases and search engines
• The Merck Manual of Diagnosis and Therapy
• The Merck Veterinary Manual
• Home Health and Pet Health

• Official website