Dear Donia,
Do I need to keep the tissue between pages of old Macklin Bibles?
Q. Dear Donia,
A. Dear Shawn,
What an excellent question! You will often find tissue covering plates in books. Sometimes this was done as the denser ink on a smoother paper in the print would take longer to dry completely than a text page so the tissue was there to protect the text until the oil in the image ink dried. Sometimes it was to protect the image from the coarser texture of the text paper. Sometimes, it was just because people were used to seeing tissue over images that that practice became the norm.
No matter the case here, the ink has dried and the books won't be used so much as to damage the images so you can safely remove the tissue. Be sure to store the Bible in a stable, low relative humidity environment and all should be good.