>>> "Eli" == Eli Zaretskii <eliz@gnu.org> writes:

   >> From: Uwe Brauer <oub@mat.ucm.es>
   >> Date: Fri, 16 Nov 2018 16:36:01 +0100
   >> 
   >> >   C-x RET c mac-roman RET C-x C-f FILE-NAME RET
   >> 
   >> That worked thank you!
   >> 
   >> 1. You did you guess mac-roman? How can I find out myself in the future?

   > The "fran\215ais" was supposed to be français, obviously, so I
   > searched the Internet for an encoding where ç is encoded as 215 octal.

Ah, ok. 
   >> 2. Is there any faster possibility?

   > Faster than what?

Then typing 
C-x RET c mac-roman RET C-x C-f FILE-NAME RET

I mean open the file, mark the region and recode the text to the correct
coding.