General Information (D-E)

Delta Metal — Delta Metal is a variety of brass containing 55 percent copper, 41 percent zinc and 4 percent various other metals.

Density — Density is the mass of a substance in relation to its volume, and usually expressed as the weight in grams of 1 cubic centimetre. Since volume enters into this dimension, and volume varies with temperature, it is essential that the temperature at which the measurement was taken is revealed when stating the density of a substance.

Deposition — In geology, deposition is a term applied to the laying-down of material by the various agents, such as wind, rivers, lakes, oceans and glaciers, each deposit exhibiting distinct characteristics.

Devonian — The Devonian was the sixth geological period, 300,000,000 years ago. It marked the evolution of the insects and amphibians.

Duralumin — Duralumin is an alloy of aluminium, copper and magnesium, with traces of other metals. Typically duralumin is comprised of 94.4 percent aluminium, 4.5 percent copper, 0.95 percent magnesium and 0.76 percent manganese. If properly tempered it has an extremely high tensile strength and is used in aircraft construction.

Dynamite — Dynamite is an explosive consisting of nitroglycerine which has been absorbed into some inert material such as kieselguhr, sawdust or wood pulp. Dynamite was invented by Nobel in 1867.

Earth — The earth is the third planet from the sun.

Earth Metal — The Earth Metals are the metals, which in combination with oxygen form alkaline earths. They are calcium, strontium and barium and are never found in an uncombined condition, but oxidize rapidly into lime, strontia and baryta, the alkaline earths.

Effervescence — Effervescence is the rapid escape of gas from a liquid, usually due to chemical action.

Element — An element is a substance that cannot be split chemically into simpler substances.

Elements — see "element"
Eocene — The Eocene was the fourteenth geological period, 50,000,000 years ago.

Eocene System — The Eocene System is the oldest of the four geological systems into which the Tertiary era is divided.

Eosin — Eosin is the potassium or sodium salt of tetrabromo-flourescein. It is a red substance which possesses brilliant flourescence in alkaline solution. It is used in acid solution as a red dye for wool and silk and is also used in red ink.

Epsom Salts — Epsom Salts is the popular name for hydrated magnesium sulphate, MgSO4.7H2O. It is used medicinally as a cathartic, and is also used for weighting textiles.

Erratics — Erratics are rocks transported by the action of ice during the Quaternary Glacial Period, often for considerable distances. They help in determining the extent of the ice-sheets and the direction of their movement.