A mass-spectrographic study of the isotopic constitution of calcium, titanium, and sulphur has been made. Two new calcium isotopes, ${\mathrm{Ca}}^{46}$ and ${\mathrm{Ca}}^{48}$, were found, present with abundances $\frac{1}{29,000}$ and $\frac{1}{520}$ that of ${\mathrm{Ca}}^{40}$, respectively. No new titanium isotopes were found. A new sulphur isotope, ${\mathrm{S}}^{36}$, was discovered, having an abundance $\frac{1}{6,000}$ that of ${\mathrm{S}}^{32}$. The proof for the existence of the new isotopes is presented. The relative abundances of the isotopes in these three elements were determined. A search for other possible rare isotopes was made in all mass number positions in the immediate neighborhood of the known isotopes. Upper limits for the existence of these hypothetical isotopes are given. A search was made for ${\mathrm{A}}^{42}$.

• Received 23 December 1937

DOI:https://doi.org/10.1103/PhysRev.53.282