Syphilis and seiseinyū: manufacturing a mercurial drug in early modern Japan

The Syphilis King consults with his minions prior to launching an invasion of the human body. Funakoshi Kinkai, “Illustrated Syphilis War Tales” (Ehon baisō gundan, 1838). Image courtesy of Waseda University Library.

Syphilis arrived in Japan in the early sixteenth century and spread rapidly through the country. The symptoms of the disease were severe but there was no truly effective treatment, and many patients thus turned in desperation to toxic substances such as corrosive sublimate (HgCl2, known in Japanese as keifun) in the hope that violent drugs might be able to expel the disease from their bodies.

A method for producing corrosive sublimate had been discovered by Chinese alchemists at least as early as the sixth century AD. The procedure involved mixing mercury, alum, and common salt into a paste and applying them to the base of a pottery vessel that was then sealed and heated over a fire while the lid was cooled with water. When the vessel was opened, the corrosive sublimate had condensed as small white crystals on the inner surface of the lid. The Japanese soon learned of and adopted this process, so by the time syphilis arrived in their country they had been manufacturing corrosive sublimate for nearly a thousand years.

Patients who consumed corrosive sublimate as a drug for syphilis would salivate and eventually suffer from suppuration of the mouth cavity. Doctors interpreted these effects as positive signs of the drug’s toxic efficacy, but the disease had an unfortunate tendency to return even after patients thought they had been cured, and there was a widespread desire for an improved formulation that might be able to cure the disease more permanently.

One such formulation was seiseinyū, a drug originally invented by the early seventeenth-century Chinese doctor Chen Sicheng. Chen had developed a large number of remedies making use of seiseinyū and published them in his book The Secret Record of Syphilis (Meichuang milu, 1636). This book was largely forgotten in China after his death, but a copy was brought to Japan and reprinted there, and it quickly became a standard reference for Japanese doctors who wished to treat syphilis using the latest Chinese methods.

Chen’s recipe for seiseinyū was similar to the standard recipe for corrosive sublimate, but it included a number of additional ingredients, the most prominent of which was an arsenical mineral called yoseki. Arsenical minerals were known to be highly toxic, but yoseki may have been included in the recipe for precisely this reason – either because doctors hoped that its toxicity would help expel the disease, or because they thought it might somehow balance the toxicity of the mercury in the recipe to yield a drug whose side effects were less severe than those of regular corrosive sublimate.

Illustration of a vessel for manufacturing corrosive sublimate and seiseinyū. Ishibashi Masaaki, “Essential Formulas for Syphilis” (Baidoku yōhō, 1810). Image courtesy of Waseda University Library.

Japanese doctors who wanted to make use of Chen Sicheng’s remedies needed to produce their own seiseinyū, but Chen’s description of his recipe was couched in unusual vocabulary that they often found difficult to interpret. Even a relatively common word like yoseki could lead to misunderstanding. In China, this word normally referred to arsenopyrite (FeAsS) or the related mineral loellingite (FeAs2); in Japan, however, this word was often understood to refer to arsenolite (As2O3), which was a common mineral obtained as a by-product from silver mines and sold commercially as “Iwami rat poison.” Many other variants of this mineral were available, ranging from a high-quality “peach-blossom” variety through yellow and white varieties to a low-quality grey variety; the choice among these varieties was thought to significantly effect the quality of the seiseinyū produced.

In contrast to the basic recipe, which was widely available in published form, these more subtle forms of manufacturing knowledge were usually passed down in secret by family lineages of doctors. It was not until the final decades of the eighteenth century that some doctors began to publish more straightforward popular accounts. In my next post, I will consider one of the more unusual consequences of this tradition of secrecy: that at least one lineage of doctors thought their family recipe for seiseinyū derived not from China, but from Europe.

Chinese and Japanese Names and Terms
J. keifun = C. qingfen 輕粉
J. seiseinyū = C. shengshengru 生生乳
J. yoseki = C. yushi 礜石
Chen Sicheng 陳司成
Meichuang milu 黴瘡秘錄
Funakoshi Kinkai 船越錦海
Ehon baisō gundan 絵本黴瘡軍談
Ishibashi Masaaki 石橋正炳
Baidoku yōhō 黴毒要方

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