Note 1 bis — PRINCIPLES OF CHEMISTRY CHAPTER XV THE GROUPING OF THE ELEMENTS AND THE PERIODIC LAW
George Kamensky translation
The crystalline forms of aragonite, strontianite, and witherite belong to the rhombic system; the angle of the prism of CaCO3 is 116° 10′, of SrCO3 117° 19′, and of BaCO3 118° 30′. On the other hand the crystalline forms of calc spar, magnesite, and calamine, which resemble each other quite as closely, belong to the rhombohedral system, with the angle of the rhombohedra for CaCO3 105° 8′, MgCO3 107° 10′, and ZnCO3 107° 40′. From this comparison it is at once evident that zinc is more closely allied to magnesium than magnesium to calcium.