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or Tabashir Tabasheer

water, lower and bamboo

TABASHEER, or TABASHIR, a markable substance occasionally found in the hollow joints of certain species of bamboo and other large grasses. It is ordinarily sought for by splitting open those bamboo stems which give a rattling sound when shaken. It is espe cially apt to be found in the Bantbusa arun dinacea of Indian and other related species of Japan, China, Java and the Andes Moun. tains. During the rapid growth of the bamboo shoots, their solid joints become hollow and are partially filled with water containing silica in solution. The development of the foliage leads to active transpiration; the water ab sorbed from the soil quickly disappears and tabasheer is the residue. It is at first )elly-like, hut gradually solidifies into small milky-white masses. Physically and chemically these are practically identical with the hydrophane variety of the mineral opal. It is an open question whether tabasheer should be registered as be longing to the mineral or the vegetable king dom. It is essentially a hydrous silica, the lime and potash which arc often present being doubt less simply impurities. Its optical properties

are most remarkable. According to Brewster, it has a lower index of refraction than any other solid or liquid, its refractive power being not only loWer than water, but so much lower as to be almost intermediate between water and air. The material is isotropic, opalescent and remarkably phosphorescent. It becomes trans parent when saturated with water and is re markably porous. It probably possesses greater absorptive power than any other mineral, Brewster claiming that the pores occupy two and one-half times as much space as the silica itself, notwithstanding the fact that they are invisible even under very high powers of the microscope. From time immemorial it has been highly esteemed in the Orient for its supposed medicinal properties. A knowledge of the substance was introduced into Europe by the Arabian physicians and its name is of Arabic origin. Much so-called tabasheer in Turkey and Asia Minor is artificial. Consult Nature (Vol. XXXV, p. 488, 1887).