Nineteenth Century Amorphous Calcium Carbonate

The work of the English anatomist George Rainey is compared with that of the Dutch naturalist Pieter Harting. While the latter is regarded as a pioneer in biomimetic inorganic crystallography for precipitating unusual crystallographic forms that mimic the products of living organisms, the work of Rainey largely has been forgotten. In fact, Rainey first prepared amorphous calcium carbonate, a material that can be molded by organisms to form biogenic crystals. Rainey’s extensive experimentation with amorphous calcareous bodies observed in a variety of organisms was at one time considered a significant and pioneering chapter in inorganic chemical morphogenesis and it should reclaim some of its former assessments. Rainey’s interpretations of crystal form and the effects of gravity on crystal growth mechanisms, however, are historical curiosities that should be left behind, except to the extent that they show how the efforts of an individual may appear diminished by the dynamic process of consensus building in science. Harting also prepared amorphous calcium carbonate, but more than a decade after Rainey. While Rainey was a quiet scholar with steady habits, Harting was a statesman, a champion of the down-trodden (albeit with prejudice), a popular educator, a temperance advocate, and a sci-fi novelist, in addition to being a professor. Harting’s public life may account for his outsized place in our collective memory. Rainey’s synthesis of amorphous calcium carbonate in the presence of gum arabic was repeated in a modern setting. Microspheres were characterized by scanning electron microscopy, established as hollow by X-ray microtomography, and were shown to have the composition of calcium carbonate by energy dispersive X-ray analysis. They were amorphous by powder X-ray diffraction.

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