glass


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glass

 [glas]
1. a hard, brittle, often transparent material, usually consisting of the fused amorphous silicates of potassium or sodium, and of calcium, with silica in excess.
2. a container, usually cylindrical, made from this material.

glass

(glas),
A transparent substance composed of silica and oxides of various bases.
[A.S. glaes]

glass

crystallophobia, hyalophobia.

glass

(glas)
1. a hard, brittle, often transparent material, usually consisting of the fused amorphous silicates of potassium or sodium, and of calcium, with silica in excess.
2. a container, usually cylindrical, made from glass.

cupping glass  a vessel of glass from which the air has been or can be exhausted, applied to the body to draw blood to the surface.

glass

(glas)
A transparent substance composed of silica and oxides of various bases.
[A.S. glaes]

glass

1. Material from which lenses and optical elements may be made. It is hard, brittle and lustrous and usually transparent. It is produced by fusing sand (silica) at about 1400ºC with various oxides (potassium, sodium, etc.) and other ingredients such as lead oxide, lime, etc. Glass may be produced in various colours by the addition of different substances (e.g. metal oxides). 2. A lens. See annealing; feathers; lens blank; strain; stria; surfacing.
absorption glass Glass which transmits only a certain portion of the incident light, the rest being absorbed.
Bagolini's glass A plano lens on which fine parallel striations have been grooved. It produces a slight reduction in acuity but a punctate light source observed through this lens appears as a streak of light orientated at 90º from the striations. Two such lenses placed in front of the eyes with the striations oriented 90º apart are used to detect sensory and motor anomalies such as, retinal abnormal correspondence, suppression, etc. Syn. Bagolini's lens; Bagolini's striated glass. See Bagolini lens test.
cobalt-blue glass See cobalt lens.
crown glass Glass characterized by low dispersion. The most commonly used crown glass in ophthalmic lenses, called ophthalmic crown or spectacle crown, has a refractive index n = 1.523 and a constringence or V-value of 59. There are other types of crown glass (e.g. dense barium crown n = 1.623, V-value 56; fluor crown n = 1.485, V-value 70). See doublet; triplet.
glass cutter A tool with a diamond-tipped edge or hard steel to cut glass.
depolished glass See ground glass.
glass eye See glass eye.
flint glass Glass containing lead or titanium besides the usual ingredients and having a high dispersion (example: Tital, V-value 31) compared with crown glass and a high refractive index (n = 1.701). It is, however, a softer and heavier material than crown. It is used in ophthalmic lenses of high power as it can be made much thinner than a crown glass lens of the same power. See doublet; high index lens; triplet.
ground glass Glass that has been ground with emery, sandblasted or etched with fluoric acid to give it a matt surface. Such glass is usually translucent but not transparent. Syn. depolished glass. See frosted lens.
magnifying glass See magnifying lens.
opal glass A white or milky translucent glass used to diffuse light.
photochromic glass See photochromic lens.
safety glass 1. Glass that has been ground and polished and then heated just below its softening point and rapidly cooled. Such treatment renders the glass highly resistant to fracture, and breakage causes it to crumble rather than shatter. Safety glass can also be produced chemically. In this process the lens is immersed in a molten salt bath (e.g. 99.5% potassium nitrate and 0.5% silicic acid at a temperature of 470ºC for some 16 hours). The lens surface thus becomes compressed as larger potassium ions replace the smaller sodium ions which are in the glass. Chemically strengthened lenses have greater impact resistance and can be made thinner than air-tempered glass lenses. However, when broken the fragments of the chemically strengthened lenses are not as blunt as those of air-tempered glass lenses. Syn. toughened glass. 2. Non-shatterable laminated glass used in automobiles and goggles. See safety lens; polariscope; industrial spectacles.
toughened glass See safety glass.
Wood's glass See Wood's light.

glass

(glas)
A transparent substance composed of silica and oxides of various bases.
[A.S. glaes]

glass

1. a hard, brittle, often transparent material, usually consisting of the fused amorphous silicates of potassium or sodium, and of calcium, with silica in excess.
2. a container, usually cylindrical, made from glass.

glass embolism
small particles of glass from a vial may be injected suspended in a fluid.
ground glass
may be used in an attempt to poison animals maliciously but has little effect. May cause transient enteritis.
glass housing
glass cover of the x-ray tube; contains the anode and cathode and the vacuum that makes generation and control of the x-ray beam possible.
soluble glass
glass in which the magnesium and calcium content have been modified from that in normal glass so that it is much more soluble in water or ruminal contents. Used in the form of a reticular retention bolus as a vehicle for therapeutic agents such as antibiotics or anthelmintics which are delivered to the animal over a period of weeks or months.

Patient discussion about glass

Q. My myopic son is wearing power glasses. Are there any other nutritional supplements to support eye sight? My myopic son is wearing power glasses from the age of 2 years. His power is not very high yet but the rate of his eye power is doubling every year. Doctor had given him some medicines and had told him to have lots of carrots. We are giving him carrot juice every day. But soon he stopped taking it for some months. But he is having juice now but I wish to know are there any other nutritional supplements to support eye sight?

A. eating carrots can help people who suffers from vitamin A or beta-carotene deficiency. which leads to poor night vision. but that's it. there is no reason to eat tremendous amounts of carrots, there are food supplements that will help you achieve it without becoming orange. anyway, getting too much vitamin A can be toxic.
here is a "snopes" about it-
http://www.snopes.com/food/ingredient/carrots.asp

More discussions about glass
References in classic literature ?
He walked the floor for half an hour puzzling over his enigma, then he hunted out the other glass plates.
His one thought was how to be revenged on that wicked old hag, and for this purpose he had a purse made large enough to contain five hundred gold pieces, but filled it instead with bits of glass.
Armed with these weapons he boldly started up the Glass Mountain.
The latter stopped walking and directed his glass towards the place indicated.
The Catalan watched him until Caderousse, almost overcome by this fresh assault on his senses, rested, or rather dropped, his glass upon the table.
He made examination of the contents, but came to the conclusion that the glass objects were unsuitable.
The doctor and the priest made scant reply to her shrill reiterations of her daughter's story, with more disturbing details of her own, to the divided vows of vengeance against Mr Glass for murdering, and against Mr Todhunter for being murdered, or against the latter for having dared to want to marry her daughter, and for not having lived to do it.
When the queen got home, she went straight to her glass, and spoke to it as before; but to her great grief it still said:
I did it with such wondrous firmness, that two panes of glass burst out of the window.
As soon as the singing was over, another and another toast was proposed and Count Ilya Rostov became more and more moved, more glass was smashed, and the shouting grew louder.
At once a pink kitten crept out of the upset cage, sat down upon the glass roof, and yawned and blinked its round eyes.
The Glass Cat yawned and stretched herself upon the floor.