Welsh Journals

SWANSEA'S COPPER CONNECTION WITH JAPAN TADASHI UCHIDA For many years I had longed to visit Swansea Museum after hearing that it pos- sessed a collection which consists of tools, products and intermediate products of copper smelting that were used in Japan centuries ago [1]. When I eventually made the trip to Swansea, I found a number of fact sheets composed by the curators of the museum, and I was taken aback by a note in one of them: the famous Michael Faraday had come to Swansea in his youth, and witnessed the production of Japan copper here in Swansea. This is actually recorded in his travel journal [2]. His visit was in the early 19th century, and Japan was still shut to all foreign countries bar only a few, while Great Britain was experiencing the blossoming start of the Indus- trial Revolution. Why was Japan copper made in Swansea at this time, and what technology was involved in its production? Below is my attempt to compare the copper smelting technologies of Japan and Great Britain at that time. JAPAN COPPER MADE IN SWANSEA Between the years 1633 and 1858, Japan was under the "enclosure" policy, i.e. it was closed to all foreign countries in order to prevent Christianity being brought in. The only exceptions were her trading partners, the East India Company of the Netherlands, China and Korea. Copper was one of the most important exports from Japan at the time, and at one stage, Japan Copper even found its way to Europe via Dutch merchants. However, by the begin- ning of the 19th century, the volume of exports had declined partly due to the exhaustion of the copper mines in Japan. The copper prepared for export from Japan at the time was called "Sao Do" (= bar-shaped copper). Smelted copper was cast into small bars of about 20cm in length, weighing about 300g per piece. About 160 to 200 such bars would make a unit weight of 100 kin (= 60kg), to be boxed into a wooden chest for export [4]. Fig. 1. "Sao Do passed down through the Sumitomo family. (Source: Sumitomo Shiryo-lcan).