MAGNESIUM. 67 



ness in atmospheric air or oxygen, it burns with 

 a vivid light, and is converted into magnesia, or 

 the oxide of magnesium. 



Magnesia is the only oxide formed by magne- 

 sium; it contains in 100 Ibs., 60.4 fts. of magne- 

 sium, and 39.6 Ibs. of oxygen. Its action on soils 

 is somewhat similar to that of lime. It is uni- 

 formly present in variable quantities, in almost 

 all limestones, and when they contain a large 

 amount, they are called magnesian limestones; 

 some varieties contain over fifty per cent, of this 

 substance. 



Should soils need magnesia, and not conveni- 

 ently applicable in combination with lime as 

 magnesia limestone, Epsom salts, or sulphate 

 of magnesia, can be 'substituted; and many far- 

 mers have found it profitable to apply magnesia 

 in this form. A crop of twenty-five bushels of 

 wheat, with the straw, would require about lllbs. 

 of magnesia, or 63 Ibs. of Epsom salts. Little 

 more need be said about this element, and as it 

 1 is found in nearly all soils, it seldom requires to 

 be added as a fertilizer. It has been noticed by 

 farmers, that lime which contains a notable 

 amount of this substance, has a more favorable 

 effect on a wheat crop than lime containing but 

 little of it. Nevertheless, lime that contains a, 

 very large quantity of magnesia may be injuri- 

 ous if the soil already contains a sufficient quan- 



