Sometimes the simplest information is difficult to find. Today I was searching for the HTML entities for French characters. Fortunately, I found the following resource French Encoding and Language Tags from Penn State.
Here’s an example of the information available on the Teaching with Technology site:
Lowercase Vowels à à (225) â â (226) ä ä (228) è è (232) é é (233) ê ê (234) ë ë (235) î î (238) ï ï (239) ô ô (244) œ œ (156) ù ù (250) û û (251) ü ü (252) ÿ ÿ (255)