General Information (C)

Calcium ammonium Calcium ammonium is a compound formed by exposing calcium to ammonia gas. It is a bronze-coloured substance which catches fire on exposure to air.

Calcium CarbideCalcium Carbide is a substance formed by heating quicklime and carbon in an electric furnace. It is a greyish crystalline substance which decomposes immediately on coming into contact with water, generating acetylene.

Cambrian — The Cambrian period was the third geological period, 450,000,000 years ago.

Carat — Carat is the unit of measurement of gold purity.

Carbide — see "carbides"

Carbides — A carbide is a compound of carbon and another element.

Carbohydrate — A carbohydrate is a complex chemical compound. Consisting of carbon, oxygen and hydrogen. In foods it forms sugars and starch.

Carbonate — A carbonate is a salt formed by the union of carbon dioxide with a base element.

Carborundum — Carborundum is silicon carbide and is extremely hard.

Caustic soda — see "Sodium hydrate"

Cautery — A cautery is a heated metal instrument used for burning or searing organic tissue.

Cement — Cement is a mixture of chalk and clay used for building.

Ceruleum — Ceruleum is a blue pigment, consisting of stannate of protoxide of cobalt mixed with stannic acid and sulphate of lime.

Charcoal — Charcoal is an amorphous form of carbon formed by charring wood.

Chlorate — A chlorate is a salt formed by the reaction of chloric acid and metal.

Chlorates — see "chlorate"

Chloric acid — Chloric acid is a oxyacid of chlorine. It is a powerful oxidising agent.

Chlorine — Chlorine is a gaseous element with the symbol Cl.

Chromatic Aberration — Chromatic aberration is the presence of prismatic colours at the edges of an optical image due to the refractive index of the lens material being different for light of different frequencies.

Climate — Climate is the average state of the atmosphere with regard to warmth, wind, rain and other variable conditions throughout a long period of time. It is dependant on the interaction of atmospheric conditions, such as wind, cloud, temperature and rainfall and on the surface features of the earth itself, such as the distribution of land and water, mountains and ocean currents. Hence it may vary considerably in places only a few kilometers apart.

Compound — A compound is a substance made of two or more elements and differing from a mixture in that the elements are present in a constant proportion no matter how or where the compound is prepared.

Concrete — Concrete is a building material of cement, sand, stone and water.

Coprolite — Coprolite is the fossilised excrement of reptiles (dinosaur dung, so to speak). They occur in the form of nodules and contain a lot of phosphatic material. The term has come to apply to any phosphatic nodule.

Cretaceous — The Cretaceous was the eleventh geological period, 95,000,000 years ago. The first marsupials evolved.

Crystal — A crystal is a body, usually bounded by symmetrically arranged plane surfaces possessing properties which differ in magnitude in different directions.

Cupro nickel — Cupro nickel is an alloy of copper and nickel

Cyanamide — Cyanamide is a colourless crystalline substance. It is the amide of cyanic acid and is prepared by the interaction of ammonia and cyanogen chloride.

Cyanic Acid — Cyanic Acid (HCNO) is a volatile liquid prepared by the distillation of urea. It is very unstable and if heated above zero degrees Celsius explodes with the formation of a polymer cyanmelide.

Cyanide — Cyanide is a salt of hydrocyanic acid. Notably potassium cyanide.