H Is for Enthalpy, Thanks to Heike Kamerlingh Onnes and Alfred W. Porter

During the 19th century the letter H sometimes represented heat, but the designation of enthalpy was placed into the scientific literature in 1909 by J. P. Dalton and credited by him to Heike Kamerlingh Onnes. In 1922 Alfred W. Porter formally proposed that H become the accepted symbol for Kamerlingh Onnes' enthalpy. During the 20th century, however, the genesis of that word became obscured by error, speculation, and use without attribution. This paper resolves current confusion about origins of the word enthalpy and its symbol H by examining their early uses in the literature.