How to save chat logs in Messages for Mountain Lion?

I always used to save my Chat logs because I use IM in the professional environment. Now I find that I can’t save chat logs anymore. That option is gone. Is there any workaround or hidden preference to enable saving chat logs again?

In Preferences, select Messages and check "Save history when conversations are closed." Now when you quit Messages, it will create a collection of chat transcripts. You can easily access these in your Library folder. From Finder, select Go>Go to Folder and type: ~/Library/Messages/Archive. If you are on Mavericks or Yosemite, the location is ~/Library/Containers/com.apple.iChat/Data/Library/Messages. This will take you directly to the appropriate folder.

Please note that the new location for logs in Mavericks is ~/Library/Containers/com.apple.iChat/Data/Library/Messages (yes, even though the app is called Messages, the container is called iChat).

This appears to be a way of replicating the way that apps like iMessages work on iOS -- Messages gets its own Library folder with its own dedicated hierarchy of files.

Update: At some point after 10.9 Mavericks and by the time of 10.15 Catalina, the real location for stored chat logs became ~/Library/Messages/Archive.

I don't know if you are still looking for an answer to this, but it looks like you can use Automator (in Applications) to copy all files to a certain folder when items are added to the Archive Folder us "Folder Action". I am trying it out now, but seems it should work.