Litmus Test Paper

For school/college laboratories. Nominal 6 mm bore glass tube. With engine divided dual scales 675 to 820 x 1 mm Hg and 26.5 to 32.5 x 0.05 inch Hg. Verniers reading 0.05 mm and 0.002 inch. Mounted on polished wooden board for wall mounting. Supplied without mercury but with instructions for filling.