American Scientist

To the Editors:

The account of Europe's reinvention of porcelain in Roald Hoffmann's "Meissen Chemistry" (July-August) reflects the confusion in Janet Gleeson's The Arcanum. Reproducing Ming chinaware using the original ingredients took longer to commercialize than she suggests. Georgian and Victorian "china" makers from Spode to Sevres fudged by adding extra and easier fluxes like bone ash and gypsum. Mullite is a product of the porcelain process, not a starting material, and the "fine needle-like crystals of mullite" in china are not "cemented by glassy silica." Mullite crystals grow out of a complex silicate melt—porcelain kilns never attain pure silica's melting point.

Despite Frederic Bottger's deserved fame as the first master of Meissen decor, the cake comes before the icing. The statuette the article captions as "made in Bottger's red stoneware around 1714 " exemplifies instead the first true mullite porcelain created by his mentor, Count Tschirnhaus around 1704. The white medallions presented as the first European porcelain are indeed Bottger's , but they're not "porcelain," but an alabaster fluxed ceramic in which wollastonite (a silicate of calcium) replaces mullite.

As Colbert's protege, Tschirnhaus got short shrift from East German historians, but his nascent materials research lab spun off the equations for caustic curves, solar furnace mirrors the size of the Hubble primary, and giant burning glass lenses subsequently used by Lavoisier.

Porcelain depicted as an alchemical Holy Grail makes a great yarn, but Bottger was no alchemist's apprentice. His master was a Prussian apothecary, and Bottger arrived in Dresden fleeing a murder warrant for poisoning him. To add to the potential for more porcelain potboilers, Bottger, ennobled after Tschirnhaus's convenient death, was caught fleeing Meissen for Vienna.

Russell Seitz
Watertown, Massachusetts

Dr. Hoffman responds:

Dr. Seitz makes a valid point by emphasizing that von Tschirnhaus's contribution to the imitation of Chinese porcelain in Europe was more important than I made it out to be. What a great scientist and technologist he was.

However, I don't think I was far off on the materials science, as complicated as it is, of the early European porcelains. What I have learned from work of Vandiver and Kingery is that when one analyzes "porcelain," one finds quartz, mullite and glass. The mullite is cemented together by a glassy matrix. Dr. Vandiver says that she has seen no evidence that the Meissen porcelain contained bone ash or gypsum, or that extra fluxes were added. Later imitators did produce high temperature ceramics using such fluxes, such as bone porcelain, like Beleek.

The area surrounding the castle workshop, that might give us further valuable evidence, has not been excavated. So much still remains to be done on the history of this remarkable episode in European technological history!