Anthracite latter in two or three sizes, all three being above in (38 mm) size on round-hole screens. High grade (HG) and ultra high grade (UHG) anthracite are the highest grades of anthracite coal. They are the purest forms of coal, having the highest degree of coalification, the highest carbon count and energy content and the fewest impurities (moisture, ash and volatiles). High grade and ultra high grade anthracite are harder than standard grade anthracite, and have a higher relative density. An example of a chemical formula for high-grade anthracite would be CHONS, representing 94% carbon. UHG anthracite typically has a
Carbon button lamp a lecture to the Institution of Electrical Engineers, in which he described the carbon button lamp in detail. He also described several variants of the lamp, one of which uses a ruby drop in place of the carbon button. Carbon button lamp The carbon button lamp is a single-electrode incandescent lamp invented by Nikola Tesla. A carbon button lamp contains a small carbon sphere positioned in the center of an evacuated glass bulb. This type of lamp must be driven by high-frequency alternating current, and depends on an electric arc or perhaps a vacuum arc to produce high current around