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hydrometer

(Encyclopedia)hydrometer hīdrŏmˈətər [key], device used to determine directly the specific gravity of a liquid. It usually consists of a thin glass tube closed at both ends, with one end enlarged into a bulb t...

aquarium

(Encyclopedia)aquarium, name for any supervised exhibit of aquatic animals and plants. Aquariums are known to have been constructed in ancient Rome, Egypt, and Asia. Goldfish have been bred in China for several hun...

solid

(Encyclopedia)solid, one of the three commonly recognized states in which matter occurs, i.e., that state, as distinguished from liquid and gas, in which a substance has both a definite shape and a definite volume....

atomic weight

(Encyclopedia)atomic weight, mean (weighted average) of the masses of all the naturally occurring isotopes of a chemical element, as contrasted with atomic mass, which is the mass of any individual isotope. Althoug...

desert

(Encyclopedia)desert, arid region, usually partly covered by sand, having scanty vegetation or sometimes almost none, and capable of supporting only a limited and specially adapted animal population. The so-called ...

variable star

(Encyclopedia)variable star, star that varies, either periodically or irregularly, in the intensity of the light it emits. Other physical changes are usually correlated with the fluctuations in brightness, such as ...

weather

(Encyclopedia)weather, state of the atmosphere at a given time and place with regard to temperature, air pressure (see barometer), wind, humidity, cloudiness, and precipitation. The term weather is restricted to co...

mushroom

(Encyclopedia)CE5 The poisonous mushroom Amanita mushroom, type of basidium fungus characterized by spore-bearing gills on the underside of the umbrella- or cone-shaped cap. The name toadstool is popularly rese...

lanthanum

(Encyclopedia)lanthanum lănˈthənəm [key] [Gr.,=to lie hidden], metallic chemical element; symbol La; at. no. 57; at. wt. 138.90547; m.p. about 920℃; b.p. about 3,460℃; sp. gr. 6.19 at 25℃; valence +3. Lan...

shaft sinking

(Encyclopedia)shaft sinking, excavation from the surface of an opening in the earth. Shafts, which are generally vertical, are usually distinguished from tunnels, which are horizontal. Little difficulty is experien...