[C.P. Thunberg and his voyage to Japan (4). Mercury water therapy for syphilis introduced into Japan by Thunberg].

During his 16-month stay in Japan from August 1775 to December 1776, Thunberg taught mercury water therapy to Japanese medical doctors and interpreters in order to help them treat syphilis, which was prevalent in Japan at that time. Kohgyu Yoshio, a Japanese-Dutch interpreter who was taught this therapy by Thunberg, recorded Thunberg's teaching in his "Kohmoh Hijiki." According to this book, the mercury water therapy that Thunberg introduced to Japan had been tested successfully by van Swieten, a Dutch doctor, about 20 years previously in Europe and used corrosive sublimate (mercuric chloride), the active ingredient, dissolved in distilled water with honey. The formula is described, in measurement units used in Europe at that time, in a letter addressed by van Swieten to a doctor in Rotterdam in 1755. The formula recorded in "Kohmoh Hijiki" in measurement units used in Japan at that time gives a content of the active ingredient equivalent to that mentioned in van Swieten's letter. This fact indicates that van Swieten's formula introduced by Thunberg was correctly accepted by Japanese doctors and interpreters, who had acquired basic medical knowledge since the publication of "Kaitai Shinsho" in 1774.