BARIUM. 



237 



moval of the mercury from the amalgam, is ineffectual. 

 As soon as this is done the ammonium is resolved into 

 gaseous ammonia and hydrogen. This change takes 

 place, indeed, spontaneously. 



585. In performing the above experiment, 



How is the 



amalgam ex- a small globule of potassium or sodium is 

 formldl peT ~ heated with a thimble full of mercury in a 

 test-tube, and a strong solution of sal am- 

 moniac added. The mercury increases in bulk without 

 losing its lustre, and continues to expand till it fills the 

 tube or glass with a light pasty amalgam. 



CLASS II. 



BARIUM, STRONTIUM, CALCIUM, MAGNESIUM. 



586. BARIUM. Barium is a soft silvery 



pro- metal, easily tarnished in the air. It is 

 ami m ade from baryta, by the process already 

 described under the head of potassium. 

 Its compounds, including baryta, from which it is pre- 

 pared, are hereafter described. Barium is soluble in 

 water and most acids. 



587. STRONTIUM. Strontium is very 



Strontium . 



description, similar to barium, but darker in color. It is 



absolvents? P roduced from strontia by a similar process. 



Its solvents are also the same. 



588. CALCIUM. The metal calcium is 



Calcium de- . . 



pro- similar to barium, and is made from lime 

 b >" the use of Potassium, as before de- 

 scribed. Its solvents are the same as those 

 of the metals above-named. 



