Rainbow bleach bottle

[ShoreBoy43]

I find quite a bit of these 32 Oz. Bleach bottles that say Rainbow on them around the top and on the bottom it says REC. U.S. PAT OFF 3
and a B with a circle around the B
It also says Rainbow around the neck of bottle does anyone know the history on these what year they are etc... I am on the Eastern Shore of Maryland digging in old farm dumps.

 

[CanadianBottles]

I've never heard of the brand of bleach, but I find that the dumps where the most bleach bottles tend to show up are the 50s ones. After that they switched to plastic, and before that I guess people just weren't using as much of it.