Stable isotopic characterization of gunpowder ingredients from the mid to late nineteenth century in Japan

Abstract

During the gunpowder-driven military revolution in early modern Japan, a huge amount of ammunition and its ingredients was imported from western countries and manufactured locally. A sum total of 24 gunpowder ingredients which survived from during the time was analyzed for δ15Nsaltpetre-nitrogen, δ34Snative sulfur and δ13Ccharcoal carbon. δ13Ccharcoal carbon, and these analyses revealed values in a narrow range from −27.6 to −25.7‰, indicating a C3 dominant wood carbon source. In contrast, δ34Snative sulfur showed fairly large variation (−1.1 to +12.3‰), and this variation reflects distinct source sulfur. High δ34Snative sulfur values (around +10‰) correspond to Sicilian sulfur (Italy) which prevailed in the world sulfur market at the time. Low δ34Snative sulfur values (∼−1.1‰) were observed for a few gunpowders (Enfield rifle, Le Faucheux revolver and artillery guns), implying a predominance of Japanese volcanic sulfur.δ15N values of nitrate-nitrogen in the form of saltpetre also varied from −2.0 to +22.0‰. Such variation was interpreted in terms of contributing two end-member nitrates, i.e., nitrate formed by a nitrification process (microbial origin), and nitrate from desert nitrate (meteoric origin: around 0‰). An anomalously high δ15N value (+22.0‰) observed for a cannon type artillery was likely a residue that was subjected to denitrification during burial in soils. Information from stable isotope analysis for saltpetre and native sulfur, but not from charcoal carbon, provides strong evidence for the provenance reflecting worldwide trading lead by some advanced nations.