Old bottles OK?

[Saxomophone]

My dad was a homebrewer back in the day, long enough ago that I don't remember him doing it and I'm 40 now. When my folks moved out of their house they gave me about 32 of those old quart beer bottles that he used to use. The bottles are in old cardboard beer cases that feel like they have some kind of wax on them to make them stronger.

Do I have to worry about the old bottles becoming brittle or anything like that or are they safe to use? I figure they must be at least 30 years old and were stored in the eves of our house.

Here's what one of the old labels looks like:

 

[badhabit]

I have been using (first with him and then on my own) my dads old long neck returnable bar bottles for longer than you have been alive. Can't speak to qt. size but the old bottles were much heavier than what you get now.