@jodi This is a Parke-Davis bottle. Info on this multinational company can be found on its Wikipedia page - https://en.wikipedia.org/wiki/Parke-Davis
It is unlikely P-D made its own bottles but it was large enough to have its identifying mark added to the bottom of bottles made for them. According to "Bottle Makers and Their Marks", the PD & Co marking is first seen in 1875. The bottle pictured above appears to be of manufacture prior to automated production so is likely to date before about 1915.
This was a huge company that made many products so all you can say, without the presence of a label, is that it contained a medicine or chemical of some kind.
