Microscopic and Diffraction Studies on Dry Cells and Their Raw Materials

A study of the manganese dioxides and other crystalline materials encountered in a dry cell has been made and five different crystal varieties of MnO 2 identified as follows : (a) pyrolusite, (b) ramsdellite, (c) cryptomelane, (d) γ MnO 2 and (e) δ MnO 2 . The last two forms are poorly crystallized. Examination of the oxides by means of the electron microscope revealed great differences in particle size and shape. Prismatic crystals of Zn ( NH 3 ) 2 Cl 2 were found in the pastes of undischarged cells, while ZnCl 2 . 4 Znlpar ; OH ) 2 occurred in small hexagonal plates in the pastes of discharged cells. X‐ray diffraction studies of thoroughly discharged mixes indicate that the manganese dioxide of a dry cell is reduced by discharge to the double salt, ZnO . Mn 2 O 3 (heterolite).