The largest use of metallic<unk>  is in steelmaking, due to its strong chemical affinity for oxygen and sulfur. Its oxides and sulfides, once formed, give liquid lime aluminate and sulfide inclusions in steel which float out; on treatment, these inclusions disperse throughout the steel and became small and spherical, improving<unk> stability, cleanliness and general mechanical properties.<unk>  is also used in maintenance-free automotive batteries, in which the use of 0.1%<unk> –lead alloys instead of the usual antimony–lead alloys leads to lower water loss and lower self-discharging. Due to the risk of expansion and cracking, aluminium is sometimes also incorporated into these alloys. These lead–calcium alloys are also used in<unk> sting, replacing lead–antimony alloys.<unk>  is also used to strengthen aluminium alloys used for bearings, for the control of graphitic<unk> rbon in<unk> st iron, and to remove bismuth impurities from lead.<unk>  metal is found in some drain cleaners, where it functions to generate heat and<unk>  hydroxide that saponifies the fats and liquefies the proteins (for example, those in hair) that block drains. Besides metallurgy, the reactivity of<unk>  is exploited to remove nitrogen from high-purity argon gas and as a getter for oxygen and nitrogen. It is also used as a reducing agent in the production of chromium, zirconium, thorium, and uranium. It<unk> n also be used to store hydrogen gas, as it reacts with hydrogen to form solid<unk>  hydride, from which the hydrogen<unk> n easily be re-extracted.<unk>  isotope fractionation during mineral formation has led to several applications of<unk>  isotopes. In particular, the 1997 observation by Skulan and DePaolo that<unk>  minerals are isotopically lighter than the solutions from which the minerals precipitate is the basis of analogous applications in medicine and in paleoceanography. In animals with skeletons mineralized with<unk> , the<unk>  isotopic composition of soft tissues reflects the relative rate of formation and dissolution of skeletal mineral. In humans, changes in the<unk>  isotopic composition of urine have been shown to be related to changes in bone mineral balance. When the rate of bone formation exceeds the rate of bone resorption, the 44Ca/40Ca ratio in soft tissue rises and vice versa. Because of this relationship,<unk>  isotopic measurements of urine or blood may be useful in the early detection of metabolic bone diseases like osteoporosis. A similar system exists in seawater, where 44Ca/40Ca tends to rise when the rate of removal of<unk> 2+ by mineral precipitation exceeds the input of new<unk>  into the ocean. In 1997, Skulan and DePaolo presented the first evidence of change in seawater 44Ca/40Ca over geologic time, along with a theoretical explanation of these changes. More recent papers have confirmed this observation, demonstrating that seawater<unk> 2+ concentration is not constant, and that the ocean is never in a "steady state" with respect to<unk>  input and output. This has important climatological implications, as the marine<unk>  cycle is closely tied to the<unk> rbon cycle. Many<unk>  compounds are used in food, as pharmaceuticals, and in medicine, among others. For example,<unk>  and phosphorus are supplemented in foods through the addition of<unk>  lactate,<unk>  diphosphate, and tricalcium phosphate. The last is also used as a polishing agent in toothpaste and in antacids.<unk>  lactobionate is a white powder that is used as a suspending agent for pharmaceuticals. In baking,<unk>  monophosphate is used as a leavening agent.<unk>  sulfite is used as a bleach in papermaking and as a disinfectant,<unk>  silicate is used as a reinforcing agent in rubber, and<unk>  acetate is a component of liming rosin and is used to make metallic soaps and synthetic resins.<unk>  is on the World Health Organization's List of Essential Medicines.
Calcium
Potassium
Phosphate
Chorus
Phosphine
High-energy phosphate
Magnesium 
Magnesium