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In 1902, Auguste Verneuil, a French scientist, developed the process of making synthetic gem sapphires. The basic material is powdered corundum (A12O3), which gives carrot-shaped crystals called boules when fused. A small amount of iron and titanium imparts a blue color; cobalt, a green color; nickel and magnesium, a yellow color; and more than five percent of chromic oxide (CrzOs), a deep red color. The process has been called the flame-fusion method because an oxy-hydrogen flame is used. The oxygen carries the powder into the center of the flame. Crystal-lographic orientation may be controlled by using small seed crystals onto which the fused droplets fall.

Researchers in the U.S. in 1967 discovered that a flame can convert electric signals directly into sound. This occurs when an electric current flows through a flame, causing particles in the gas of the flame to become electrically charged. Then, by varying the current of the imposed signals, the particles are made to move accordingly, and it is this movement and its effect on the surrounding air that generates sound waves.

WATER GAS, a manufactured gas mixture of hydrogen and carbon monoxide produced by passing steam over incandescent coals, usually in tie form of coke. It is nonluminous and burns with a blue flame, and for this reason is known as blue gas. Enriched with hydrocarbon gases derived from petroleum, it becomes an efficient illuminating gas with a fuel value increased from about 300 Btu. (British thermal units) to about 539 Bru. per cubic foot. In this stage it is called carbureted water gas, and is much more poisonous than coal gas because of its high carbon monoxide content.