http://en.wikipedia.org/wiki/Magnesium_sulfateIt is often encountered as the heptahydrate, MgSO4·7H2O, commonly called Epsom salt.
new to me too.The British Pharmacopoeia (BP) is the official collection of standards for UK medicinal products and pharmaceutical substances.
Yes use James' calculator, Epsom Salts will always be the heptahydrate form, as MgSO4 is unstable and will take in atmospheric moisture. To make anhydrous MgSO4 it is heated, to drive off the "water of crystallisation", and then kept in a dessicator. MgSO4.7H2O only contains about 10%Mg as you have to add 7H2O to the RMM calculation (see the formula earlier in the post).I take it from The james calculator set up for heptahydrate form of magnesium sulphate compared to the UKAPS dosing guide for just MgS04 the only difference seems to be that epsom salts are in higher quantity's to achieve the ppm.