200 - Frédéric KNAPP (1804 - 1904) (2)  
On 9 June 1877, Friedrich KNAPP had applied for a patent under the title of « Nouveau procédé de tannage de peaux au moyen de sels de peroxide de fer ». (see No 193)
Four months later, on 24 October 1877, he applied for a second patent for his new process of tanning hides and skins under the title of:
Gerbeverfahren mittelst Eisensalzen und deren Zubereitung von bis dahin noch nie angewendeten Eisenseife
Since the corresponding administrative files are not available at the National Archives, no further information on the technical content of the files, nor on the patenting processes, can be obtained.
The earlier application (No 193) was possibly directed to the compound and the later (present) application towards the use of the compound in the tanning process. This view is supported by the corresponding two patents obtained by KNAPP in the USA. 
The earlier patent was granted, but there is no evidence that the present (second) application proceeded to grant.
 Schneider, Wolfgang, "Knapp, Friedrich" in: Neue Deutsche Biographie 12 (1980)
 FamilySearch database
 US patents No 193,520 (chemical compound) and No 193,521 (art of tanning); CA patent No 8,838 (chemical compound); DE Reichspatent No 444 (compound, process and apparatus)