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

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.