The latest version of this browser can be downloaded from Softpedia
The second Alpha release in the new Firefox 27.x branch has been made available for download by Mozilla for all available platforms, including Linux.There is little to no information about this new branch of Firefox, 27.x, and Mozilla has yet to publish any details, but that doesn't mean that it doesn't work.
As always, the binaries for Mozilla Firefox 27 Alpha 2 can be downloaded and run without having to install anything.
You can also check the proposed features for this latest development branch, when they become available. For now, you will have to settle with a 404 error.
Download Mozilla Firefox 27 Alpha 2 for Windows
Download Mozilla Firefox 27 Alpha 2 for Linux
Download Mozilla Firefox 27 Alpha 2 for Mac OS X
Remember that this is a development version and it should NOT be installed on production machines. It is intended for testing purposes only.