—, S. Woodruff, xxiv, 363.
Hydrargillite, C. Dewey, iii, 239.
Hydrate of magnesia, from Shetland, vii, 365.
Hydraulic cement in N. York State, xxxvi, 45.
— limestones of N. York, xxxix, 96; xlvi, 29.
— — in the Appalachian chain, xxxvii, 381.
— —, magnesian character of, xxxvii, 381.
— machine, new, ii, 345.
— ram, new, iii, 381.
— volcano, xxii, 358.