Zolotnik Zolotnik A zolotnik (in Russian: золотни́к; abbr.: zol.) was a small Russian unit of weight, equal to 0.1505 avoirdupois ounces, or 4.2658 grams (about 65.83 grains). Used from the 10th to 20th centuries, its name is derived from the Russian word "zoloto", meaning gold. As a unit, the zolotnik was the standard for silver manufacture, much as the troy ounce is currently used for gold and other precious metals. This unit was originally based on a coin of the same name. The zolotnik circulated in the Kievan Rus until the 11th century; it was equal in weight to the Byzantine
Heavy metals cooling towers. Depending on their intended use as fertilisers or biocides, agrochemicals may contain heavy metals such as chromium, cobalt, nickel, copper, zinc, arsenic, cadmium, mercury, or lead. Selected heavy metals are used as catalysts in fuel processing (rhenium, for example), synthetic rubber and fibre production (bismuth), emission control devices (palladium), and in self-cleaning ovens (where cerium(IV) oxide in the walls of such ovens helps oxidise carbon-based cooking residues). In soap chemistry, heavy metals form insoluble soaps that are used in lubricating greases, paint dryers, and fungicides (apart from lithium, the alkali metals and the ammonium ion form soluble soaps).