334 MAGNESIA. 



be taken not to inhale it in any quantity. In the process, how- 

 ever, above described, it is so gradually evolved, as not to occasion 

 inconvenience; audit may thus be diffused even in the chambers 

 of the sick, without the slightest annoyance. Under every cir- 

 cumstance, whether infection be suspected or not, unpleasant 

 exhalations are instantly destroyed by this salutary process, and 

 a freshness communicated to the air, which does not merely cover 

 disagreeable smells, like common fumigations, but effectually 

 destroys them. The chloride is cheap and easily procured; and 

 the quantity of a table -spoonful, stirred into as much water as 

 may be contained in a soup-plate, and renewed every two or 

 three days, is quite sufficient in all ordinary cases. In 

 sick-rooms, to destroy the odour of discharges from confined 

 patients, and in fevers of a decidedly contagious character, the solu- 

 tion should be sprinkled about the chamber, and the linen of the 

 patient thrown into a pail of water, in which double the above 

 quantity of the salt has been mixed. But, besides the property 

 which belongs to the chloride of lime of disinfecting foul air, it 

 has also been medicinally employed as an excellent lotion for 

 excoriations, chilblains, foul ulcers, and gangrenous sores. The 

 solution is likewise used as a gargle in putrid sore throat; and forms 

 the best lotion in ptyalism hitherto discovered. 



Genus II.— MAGNESIA. 



This earth has been discovered pure in the mineral kingdom; but 

 more commonly combined with silica, alumina, lime, and other 

 earthy substances, or with acids, and in solution in sea-water, and 

 several mineral springs. 



Sp.l. Native Magnesia. Brace. — Its colour is snow-white, 

 occasionally with a tinge of green. It occurs massive, and in 

 granular and prismatic concretions. Tt is semi-transparent, with 

 a shining and pearly lustre, but, by exposure to the weather, the 

 surface becomes dull and opaque; it adheres slightly to the tongue, 

 and is so soft as to yield easily to the nail. Its specific gravity is 



