I changed out an old light switch (that was arcing the in the box - you could hear it) for my 73 year old mother-in-law. I was just curious if anyone could help identify how old it is. The house it came from was built about 1920 in Mobile, AL.

The single pole switch is black with a ceramic surround and exposed leg switch on the left side. No ground screw. On the back is stamped "J.I.P." and "975". On the face of the switch, it is stamped "J.I.P. Inc, Und Labs Insp". The writing on the lower half of face of the switch is blurred (due to charring). Was this original?