Nine-volt battery batteries were formerly made in this size. They had higher capacity than the then-standard carbon-zinc types, a nominal voltage of 8.4 volts, and very stable voltage. Once used in photographic and measuring instruments or long-life applications, they are no longer manufactured as mercury is highly toxic and accumulates in the ecosystem, posing a risk to humans and wildlife. Most battery voltage testers and chargers that can also test nine-volt need another snap clip to hold the battery, while cylindrical batteries often share a holder that may be adjustable in size. Because of the proximity of the positive and negative terminals
Period 6 element electrodes, platinum-resistance thermometers, dentistry equipment, and jewelry. Because only a few hundred tonnes are produced annually, it is a scarce material, and is highly valuable and is a major precious metal commodity. Being a heavy metal, it leads to health issues upon exposure to its salts, but due to its corrosion resistance, it is not as toxic as some metals. Its compounds, most notably cisplatin, are applied in chemotherapy against certain types of cancer. Gold is a dense, soft, shiny, malleable and ductile metal. It is a chemical element with the symbol Au and atomic number 79. Pure gold has