There are many perspective of hot springs. The medical effects of hot springs (hot spring medicine) have been recognized for ages. Hot springs gradually became part of people’s lives, and gave rise to a hot spring culture. During this process, engineering technology (hot spring engineering) was incorporated in order to make efficient use of the hot springs, and law and sociology were put into effect to resolve conflicts that may arise in the use of hot springs.
　Fundamentally related to the science of hot springs are these various aspects: the water; heat and constituents that form the hot spring; the properties of the geological strata that contain and make the hot spring water flow, and other physics that are related to the phenomena of hot springs (geoscience of a hot spring). Modern research in this field as mentioned in “Chapter 2: The beginning of Hot Spring Science-Bunsen’s Achievement” began in 1846 when Bunsen conducted his field study in Iceland. However, there weren’t many studies on geoscience conducted in the western European countries, in part because of the large attention focused towards the medical use of hot springs.
　However, in Japan, ongoing research in this field had been underway since the Meiji era. Unfortunately, this is not widely known. An overview of the background of the research will be introduced in a few sections below. However, please keep in mind that the content written below is focused on the author’s interest.

(1) Research studies up till around mid Meiji era- The making of an Onsen Catalog
　During the Edo/Tenpo era (around 1830s- 40s) in Japan, research regarding spring types was conducted by Yoan Udagawa and others. At the end of Edo period, during the Keio era (late 1860s), Renshinsha, a chemical research organization formed in Kyoto, had conducted analysis on hot springs while also offering lectures and conducting research on chemistry and pharmacology.
　Within this context, in July 1873, right after the Meiji restoration, the Ministry of Education of the new administration issued an edict to conduct studies on the origins and efficacy of mineral springs all over Japan. In 1874, the analysis of mineral springs began in the Medical and Pharmaceutical Test Center in Tokyo. This was largely due to the influence of modernization from Iwakura's mission to western countries from 1871 to 1873 (an influence that is fortifying the country and strengthening the military/increasing production and encouraging new industries).
　Furthermore, under the order of Home Ministry, mineral springs in various locations were evaluated in detail and compared with famous mineral springs in Europe. The results were then published as The Mineral Springs of Japan. In 1886, the study results of mineral springs from various prefectures were exhibited at the Mineral Spring Exhibition that was held in Germany. A report was then compiled and published in The Mineral Springs of Japan Vol. 1, 2, 3 (edited by the Hygiene Bureau of Home Ministry).
　This was the first structured full-fledged guide on Japanese hot springs, also known as the Hot Spring Catalog of Japan. The definition of mineral springs, their difference from normal water, treatment efficacy, usage and management method, the geographical names of hot springs, spring types, the number of hot spring-users and the exact date of discovery was stated in the catalog. The listed spring types were categorized into simple thermals, acid springs, carbonated springs, saline springs, sulfur springs, and unknown spring type according to their chemical composition.
(The above was mentioned in "The Guideline of Hot Springs" by Yasuzo Hattori (1959), published by Shoten.)

Analysis in Beppu
　In December 1888, shortly after the publication of The Mineral Springs of Japan, the “Analysis and the Efficacy of Treatment of Kannawa Steam-vaults and Hot Springs” booklet was published in Kannawa, Beppu. The sketches of bathing procedures and effects of Kannawa Mushiyu (steam bath) were recorded in it. The constituents of both “Shibu no Yu” and “Netsu no Yu” were noted as well. However, the values were based on solid content, showing a qualitative amount of each individual constituent. The temperature and the pH of the springs were not recorded.
　The extracted analytical results of the main constituents from “Shibu no Yu” and “Netsu no yu” are shown below. From this you will be able to get a glimpse into the research conducted on hot springs at that time.

(Source: Ikusaburo Kawasaki (1888): Analysis and the Efficacy of Treatment of Kannawa Steam-vaults and Hot Springs (Revised by : Hidetoshi Irie)
　 Although not included in the above table, bicarbonic acid (hydrogen carbonate ion) was recorded as "minimal" or "trace" in the original report. Therefore the spring type might have a mildly acidic pH. (Refer to Spring Type)

The beginning of geoscience research 　As the production of the hot spring catalog proceeded, geoscience research and studies on hot springs began to take root. For example, in February 1905, under the request of Toshitake Okubo, the prefectural governor of Oita, mine supervisor Shigeru Matsuda took on the research of Beppu hot springs and Hamawaki hot springs. However, as illustrated in the reports submitted in March 1905, he found that the studies on the geological condition and volcanic activities had progressed considerably. The front cover of said report is shown in the appended figure. Specific contents of the report will be elaborated on separately. (Acknowledgement) “Analysis and the Efficacy of Treatment of Kannawa Steam-vaults and Hot Springs” was provided by Hidetoshi Irie and Tadayuki Kawano. The study report written by Shigeru Matsuda was provided by the Specified Non-Profit Corporation of Beppu Hatto Trust. The two references are tremendously valuable for the whole of Japan. Given that, I would like to express my deepest gratitude to the above parties.

(Figure: the front cover of said report)

↑TOP