I found a 2007 interview that Art did with George Knapp where Knapp mentions actually seeing Element 115. He also mentions that you can see the container where it is stored in a news report he did in 1990 (I can`t find that video though... if anyone can point me to it, I`d love to see it).
I hesitate to mention this since it seems the parties involved are now saying "No comment" when asked about 115, but since this already aired on the radio, I guess it`s not a secret.
You can find the audio on Youtube under the title "Classic Art Bell - Skinwalker Ranch and Area 51". This is my first post (longtime listener, first time poster), so I`m not sure you if are allowed to post Youtube links here.