A process in nature in which organisms possessing certain genotypic characteristics that make them better adjusted to an environment tend to survive, reproduce, increase in number or frequency, and therefore, are able to transmit and perpetuate their essential genotypic qualities to succeeding generations.
A watchglass can be used as a beaker cover, but you can also place small amounts of chemicals on it and then heat it (for example, to evaporate some water from a wet chemical). From Wikipedia: A watch glass is a circular, slightly concave piece of glass used in chemistry as a surface to evaporate a liquid, or as a cover for a beaker. The latter use is generally applied to prevent dust or other particles entering the beaker; the watch glass does not completely seal the beaker, and so gas exchanges still occur.
Glassmaking is one of the primary uses of quartz. Â© iStockphoto / Chinaface. One of the first uses of quartz, in the form of flint, was the production of sharp objects such as knife blades, scrapers and projectile points such as the arrowheads shown above.Â© iStockphoto / Leslie Banks. Quartz is often used in jewelry or as a gemstone.s quartz, it has a hardness of 7 (harder than steel) and is used as a whetstone for sharpening knives. Aventurine is colorful variety of quartz that contains abundant shiny inclusions of minerals such as mica or hematite.