In snapshot 14w04b there was a fix that made spawners load into the world properly. With lack of spawners in my world I tried to test this. I loaded a copy of my world (as well as my world to be sure) and found that x-ray machines didn't work. I reverted to 1.7.4 and went into my survival world; the items in the chunks that were loaded (thankfully not my storage room) had no items in them. One of the furnaces was even on without anything to smelt.