Content ：98.0 per cent to 100.5 per cent of MgO (ignited substance).

Appearance ：Fine, white, amorphous powder.

Solubility ：Practically insoluble in water. It dissolves in dilute acids with at most slight effervescence.

Identification ：

A. 15 g has an apparent volume before settling of about 150 ml.

B. Dissolve about 15 mg in 2 ml of dilute nitric acid R and neutralise with dilute sodium hydroxide solution R. The solution gives the reaction of magnesium .