fortis and lenis

[Herb Stahlke]

I've been looking for 19th c. uses of the terms fortis and lenis.
The earliest the OED gives is Webster's 1908 followed by a series
of linguistics articles starting from the early 1930s.  I checked
several etymological dictionaries, including Klein's, and fortis
does not show up.  Lehmann, in his _A Reader in Nineteenth-Century
Historical Indo-European Linguistics, translates something in
articles by von Raumer (1856) and Grassmann (1863) as "hard" and
"soft" in reference to consonants that have also been classified
as fortis and lenis.  As much as those sound like reasonable
translations for fortis and lenis, I don't have access here to the
German originals to check against.  I checked several German
dictionaries and the one German etymological dictionary our
library has, and fortis and lenis don't show up there either.
Does anyone know of earlier uses of the terms than Webster's, in
English or elsewhere?

Thanks,

Herb Stahlke