140

Magnesia.

r

M

R K.

Magnefia is a peculiar earth, foraiing, when u-nited to the vitriolic acid, a purgative fair, eafilyfoluble in water, whilft common abforbent earth s,united with this acid, form Compounds aftririgentand fcarcely foluble.

In feparating Magnefia from this falt, a doubleelective attraclion takes place, the acid leaving theMagnefia, and joining the mild Kali, whilft theMagnefia receives the fixed älr difcharged from theKali : hence two new produäs, a vitriolated Kaliand Magnefia united with fixed air. The formeris diflblved by water, the latter is precipitated. Icis in general efteem for correfting acidity in the fto-mach of children, in whom it generally proves lax-ative when given from a fcruple to a dram. Toadults it is given more largely in Cardialgia, &c.

MAGNESIA USTA.Burnt Magnesia.

Take of white Magnefia four ounces byweight.

Expofe it to a firong heat for two hours;and, when cold, put it into a glafs veflel to beclofe ftopt.

REMARK.