The relative abundances of isotopes have been investigated extensively in recent years, but few researches of such ratios when one isotope is very rare have been reported. We have investigated a number of samples of hydrogen from various sources, water from the crater of Mc. Kilauea, an obsidian, Devonian water, and hydrogen from helium bearing natural gases. The spectrographic method used for detection is not free from objections, but the results show that there is no appreciable variation of abundance of ${\mathrm{H}}^{2}$ in the samples investigated.