48 
29. Manganesum may be procured from the 
mineral called manganese, by intensely igniting it 
in a forge mixed with charcoal powder. It is a 
metal very difficult of fusion, and very combus- 
tible : its specific gravity is 6850. The number 
representing it is 177 . 
30. Potassium is the lightest known metal, being 
only of specific gravity 850. It fuses at about 
150°, and rises in vapour at a heat a little below 
redness. It is a highly combustible substance, 
takes fire when thrown upon water, burns with 
great brilliancy, and the product of its combus- 
tion dissolves in the water. The number repre- 
senting it is 7 5. It may be made by passing fused 
caustic vegetable alkali, the pure kali of druggists, 
through iron turnings strongly ignited in a gun 
barrel, or by the electrization of potash by a strong 
Voltaic battery. 
31. Sodium may be made in a similar manner to 
potassium. Soda, or the mineral alkali, being sub- 
stituted for the vegetable alkali. It is of specific 
gravity 940. It is very combustible. When 
thrown upon water, it swims on its surface, hisses 
violently, and dissolves, but does not inflame. 
The number representing it is 88. 
32. Lithium is a metal procured from a newly- 
discovered mineral alkali, very similar to sodium 
in its properties. 
33. Barium has, as yet, been procured only by 
electrical powers, and in very minute quantities, 
so that its properties have not been accurately 
examined. The number representing it appears 
to be 130. 
