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General Science history

A gift fit for a King?

Adoration of the Magi, Andrea Mantegna, 1431-1506. Digital image courtesy of the Getty's Open Content Program.
Adoration of the Magi, Andrea Mantegna, 1431-1506. Digital image courtesy of the Getty’s Open Content Program.

There is currently a very thought provoking painting on display at the British Museum (although it will soon be gone, the Ming: 50 years exhibition, of which it is a part, ends on 5th January). The painting depicts the moment that the three kings, (or three wise men) present their gifts of gold, frankincense and myrrh to the Christ child. The three kings are on the right of the picture. Notice Melchior however, who is presenting gold to Jesus at the bottom of the painting. He presents his gold gift in a porcelain cup. The painting suggests just how valuable porcelain was to the Europeans of the 15th-16th century.

For many years, the Chinese had the monopoly on porcelain production and they ensured that the recipe was kept secret. Nonetheless, by the 17th century porcelain was being traded with Europe and by the 18th century the Europeans had started to mass produce it. Bramah has argued (in the excellent book “Coffee Makers”) that the explosion in popularity of tea and coffee drinking in Europe during the 17th-18th century was due to the introduction of porcelain into general use and its mass production. So it is worth taking a closer look at one of the key figures in the production of ceramics: Josiah Wedgwood.

Wedgwood painting
Portrait of Josiah Wedgwood, FRS. © Trustees of the British Museum

As a ceramics maker, Wedgwood (1730-1795) was interested in ensuring his pottery came out of the furnace well each time and to do that, he realised that he had to know the temperature of the oven. Other pottery producers of the time judged the furnace temperature by the colour (red hot, white hot etc), Wedgwood asked if there was a better way. Eventually he designed a “pyrometer” (“fire” meter) made from bricks of Cornish clay. Wedgwood used the fact that the clay shrank when fired. The amount that the clay shrank indicated the temperature of the oven. Wedgwood could then quantify what was “red” hot etc. Of course, there were problems. Wedgwood’s thermometer worked at temperatures of around 1000ºC, where ordinary alcohol or mercury based thermometers could not be used. How can the temperature scale (that became known as degrees Wedgwood) be correlated with the temperature scales that we are familiar with (such as degrees Centigrade)? Another, perhaps more significant problem was that the technique was not transferable to other practitioners, different clays shrank by different amounts. The Wedgwood scale required a specific Cornish clay. It was left to Louis-Bernard Guyton de Morveau to improve the pyrometer, basing his high temperature thermometer on the expansion of platinum. Today, we use devices based on electrical properties of metals to measure such high temperatures.

A porcelain bird feeder (1426-1435) from the Ming dynasty. © Trustees of the British Museum
A porcelain bird feeder (1426-1435) from the Ming dynasty. © Trustees of the British Museum

If you are in London, it is worth popping along to the Ming 50 years exhibition before it closes on 5th January 2015. Along with this painting, there are many examples there of excellent Chinese porcelain. One of the things that struck me as I went around the exhibition was just how annoyed visiting European diplomats must have been if they ever visited the Imperial palaces. Not only did the Chinese use this rare and valuable porcelain for cups, they also made exquisitely designed, porcelain, floor tiles and bird feeders. While in Europe we were struggling to make any porcelain, the Chinese were not only walking on bits of this valuable material, they were allowing their birds to feed from it too! An interesting history for next time you take a sip from your favourite mug.

Please leave any comments using the form below. I am very grateful to the image reproduction polices of the British Museum and the Getty Museum for the images shown in this article. Information was taken from:

“Coffee Makers”, Bramah&Bramah, Quillar Press Limited, 2002

“Inventing Temperature”, Hasok Chang, Oxford University Press, 2007

 

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