Magnesium+Sulphate

[|Anhydrous] magnesium sulfate is used as a drying agent. Since the anhydrous form is [|hygroscopic] (readily absorbs water from the air) and is therefore difficult to weigh accurately, the hydrate is often preferred when preparing solutions, for example in medical preparations. Epsom salt has been traditionally used as a component of [|bath salts].
 * Magnesium sulfate** (or magnesium sulphate) is a [|chemical compound] containing [|magnesium], [|sulfur] and [|oxygen] , with the formula MgSO4. It is often encountered as the heptahydrate [|epsomite] (MgSO4·7H2O), commonly called **Epsom salt**, from the town of [|Epsom] in [|Surrey] , England, where the salt was distilled from the springs that arise where the porous chalk of the [|North Downs] meets non-porous London clay. Another [|hydrate] form is [|kieserite].

Magnesium sulfate is the primary substance that causes the absorption of [|sound] in [|seawater]. [|[1]] // Absorption //, in this case, means the conversion of acoustic energy to heat energy. The conversion is a strong function of frequency. Lower frequencies are less affected by the [|salt], so that the acoustic energy travels much farther in the ocean. [|Boric acid] also contributes to absorption, but the most abundant salt in seawater, [|sodium chloride], has no known effect on sound absorption.

Almost all known mineralogical forms of MgSO4 occur as hydrates. [|Epsomite] is the natural analogue of "Epsom salt". Another heptahydrate, the [|copper] -containing mineral alpersite (Mg,Cu)SO4·7H2O, [|[2]] was also recently recognized. Both are however not the highest known hydrates of MgSO4, due to the recent terrestrial find of [|meridianiite], MgSO4·11H2O, which is thought to also occur on Mars. [|Hexahydrite] is the next lower (6) hydrate. Three next lower hydrates - [|pentahydrite] (5), [|starkeyite] (4) and especially [|sanderite] (2) are more rarely found. [|Kieserite] is a monohydrate and is common among evaporitic deposits. Anhydrous magnesium sulfate was reported from some burning coal dumps, but never treated as a mineral.

The pH of hydrates is average 6.0 (5.5 to 6.5). Magnesium [|hydrates] have, like [|Copper(II) sulfate], [|coordinated water]. [|[3]]