Back in 2006 George made this post

Quoted from George Willson Silent movies didn't use subtitles - they didn't have the technology yet. They used intertitles -- those cards that fit in the scenes to tell the viewer what people were saying. These cards were actually physical cards made by someone. One of Alfred Hitchcock's earliest film jobs was doing intertitle cards.

It is relevant to my question but the masses don't like bumping up old posts and that post wasn't exactly on the same subject.

Anyway in his post he mentions "intertitles" as what they used and I'd like to know how to write them into a screenplay.

I could guess but I would like to do it right for my final feature.

The way it is written just doesn't seem right to me and any other way I could think up would just not feel right.

Any help would be great. Thanks in advance.

Probably nothing more complicated than TITLE CARD: "Let go of my hand, you dirty awful man!" They would be placed at the point between the action paragraphs where they would most logically go in the finished film.

That's one of those things you would make as clear as possible since an actual standardized "screenplay format" didn't exist when these were in regular usage. I know there are silent films on SS, but the scripts weren't billed as screenplays; they were scenarios, so I would doubt that many of the script for silent films you'd find on the net would be what these people used to make their movies. Sure, it's possible, but I would do what I have above to notate it in a modern screenplay. If you're going for a silent movie look, you'd probably want to notate that as well at the top of the section you're doing it in.

Actually I've read a few silent films.  You could just write it in like normal dialog in a dialog box, just the same exact way, just don't write the character over it, it is very easy to read and not confusing, and you wont have to be writing in Title Card over and over again.

This one, The Phantom of the Opera, just inserts it as quoted dialogue:

http://www.geocities.com/emruf1/poto.html

This one, The New York Hat, calls them Sub-titles:

http://www.geocities.com/emruf1/nyhat.html

Both were linked from the SS silent scripts page, and both work just fine.

I think it's like George says, in that there was no standardized format at he time, you'd just want to do what feels right and presents it in the most understandable fashion.