| ultramarine | <chemistry> A blue pigment formerly obtained by powdering lapis lazuli, but now produced in large quantities by fusing together silica, alumina, soda, and sulphur, thus forming a glass, coloured blue by the sodium polysulphides made in the fusion. Also used adjectively. Green ultramarine, a green pigment obtained as a first product in the manufacture of ultramarine, into which it is changed by subsequent treatment. Ultramarine ash or ashes, a pigment which is the residuum of lapis lazuli after the ultramarine has been extracted. It was used by the old masters as a middle or neutral tint for flesh, skies, and draperies, being of a purer and tenderer gray that produced by the mixture of more positive colours. Fairholt. Origin: Cf. Sp. Ultramarino. So called because the lapis lazuli was originally brought from beyond the sea, from Asia. Source: Websters Dictionary (01 Mar 1998) |
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| ultramicroscope | <instrument, microscopy> A term applied to particles less than 0.1 ~m in diameter, hence too small to be truly resolved by the light micro- scope. Under the ultramicroscope they look like stars in the sky. Their differences in size are merely indicated by differences in brightness. (05 Aug 1998) |
| ultramicroscopic | <optics> Particles which, although visible in the ultramicroscope, are too small to be resolved by visible light. This places their size between 0.2 Lm and 0.005 Lm. (05 Aug 1998) |
| ultramicrotome | A microtome used in cutting sections 0.1 um thick, or less, for electron microscopy. (05 Mar 2000) |
| ultramicrotomy | The cutting of ultrathin sections for electron microscopy by use of an ultramicrotome. (05 Mar 2000) |
| ultramontanism | The principles of those within the Roman Catholic Church who maintain extreme views favoring the pope's supremacy; so used by those living north of the Alps in reference to the Italians; rarely used in an opposite sense, as referring to the views of those living north of the Alps and opposed to the papal claims. Cf. Gallicanism. Origin: Cf. F. Ultramontanisme. Source: Websters Dictionary (01 Mar 1998) |