Is this outlet grounded?
Back in 1949 when your house was built, the code of the time allowed the metal shielding of the BX cable to be used as a ground. Over time these connections degrade from corrosion, and the grounding could eventually fail. Oftentimes, when a home is renovated to use non-metallic wiring (NM), the ground to existing BX cable can also become disconnected. This is likely the case with your house.

There still is a possibility that the ground is intact, but it is unlikely. You can test this with an inexpensive outlet tester like pictured below. These typically run around $10, and are a good investment. In your case, you would probably see that this outlet has an open ground. Make sure that the outlet is properly secured to the box before you test it.



If you find that the outlet is not grounded, you should avoid using it until you can have that part of your home rewired.