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A hydrous silicate of alumina and baryta, occurring usually in white cruciform crystals; cross-stone.

The denuded stems or stalks of such crops as buckwheat and the cereal grains, beans, etc.; straw.

See Haulm, stalk. Smart.

bstance found in the root of the elecampane (Inula helenium), and extracted as a white crystalline or oily material, with a slightly bitter taste.

A glucoside obtained as a white crystalline substance by partial oxidation of salicin, from a willow (Salix Helix of Linnæus.)

side accompanying helleborin in several species of hellebore, and extracted as a white crystalline substance with a bittersweet taste. It has a strong action on the heart, resembling digitalin.

A poisonous glucoside found in several species of hellebore, and extracted as a white crystalline substance with a sharp tingling taste. It possesses the essential virtues of the plant; -- called also elleborin.

A reddish brown or violet crystalline substance, C16H12O6, got from hematoxylin by partial oxidation, and regarded as analogous to the phthaleins.

so called because of the red color of the powder. It occurs in splendent rhombohedral crystals, and in massive and earthy forms; -- the last called red ocher. Called also specular iron, oligist iron, rhombohedral iron ore, and bloodstone. See Brown hematite, under Brown.

A crystalline or amorphous pigment, free from iron, formed from hematin in old blood stains, and in old hemorrhages in the body. It resembles bilirubin. When present in the corpora lutea it is called hæmolutein.

Having half of the similar parts of a crystals, instead of all; consisting of half the planes which full symmetry would require, as when a cube has planes only on half of its eight solid angles, or one plane out of a pair on each of its edges; or as in the case of a tetrahedron, which is hemihedral to an octahedron, it…

The property of crystallizing hemihedrally.

Having the two ends modified with unlike planes; -- said of a crystal.

A substance, in the form of reddish brown, microscopic, prismatic crystals, formed from dried blood by the action of strong acetic acid and common salt; -- called also Teichmann's crystals. Chemically, it is a hydrochloride of hematin.

Half turned round; half inverted; (Crystallog.) having a twinned structure.

Twin composition in crystals.

rterial blood, it is always combined with oxygen, and is then called oxyhemoglobin. It crystallizes under different forms from different animals, and when crystallized, is called hæmatocrystallin. See Blood crystal, under Blood.

The sulphate of iodoquinine, a substance crystallizing in thin plates remarkable for their effects in polarizing light.

A rare fluophosphate of glucina, in small white crystals.

A white, crystalline substance having a sweetish taste, obtained by the decomposition of hesperidin, and regarded as a complex derivative of caffeic acid.