1859.] Lithium, and their Congeners. 81 



that time been isolated. This conception was first verified by Sir 

 Humphrey Davy in 1807, and has since been abundantly realized. 

 From their characteristic property of neutralizing acids to form salts, 

 the earths and alkalies received the name of bases, and the metals 

 eventually extracted from them became known as basic or basylous 

 metals. Some of these metals, particularly those obtained from mag- 

 nesia, lime, and lithia, have only of late been procured in quantities 

 sufficient to allow of a demonstration of their properties. 



The highly basylous and the commercial metals are alike obtained 

 by three principal processes, namely electrolysis, precipitation by means 

 of another metal, and reduction by charcoal at a red or white heat. 



a. Electrolysis. — Very many metallic compounds, when submitted 

 to the action of a galvanic current, are decomposed, with a deposition 

 of metal upon the negative pole of the battery. Although a cheap 

 electrolytic process has been devised for the extraction of copper from 

 its ores, yet, altogether, electrolysis is too expensive to admit of employ- 

 ment for the mere separation of the commercial metals. It is, however, 

 largely applied in the fine and useful arts for the production of different 

 metals in certain required forms, as in the well-known operations of 

 electrotyping, electroplating, &c. The liquid state, which is an 

 essential condition for electrolysis, is usually obtained by dissolving 

 the metallic compound in water ; but for procuring the highly basylous 

 metals, this means does not succeed, inasmuch as these metals cannot 

 exist in contact with water. The basylous metals seem indeed to be 

 deposited upon the negative pole ; but, simultaneously with their pro- 

 duction, they are acted upon by the water of the solution, and thereby 

 converted into the state of caustic alkali. The liquid condition is con- 

 sequently attained by means of fusion. Certain salts of the basylous 

 metals, usually the chlorides, from their ready fusibility, are melted in 

 suitable crucibles, and then submitted to electrolysis ; this is the only 

 mode by which the metals calcium and lithium are obtainable. 



/3. Precipitation of one metal by another. — This process is largely 

 employed on a manufacturing scale. At the mines of Freyburg, me- 

 tallic silver is obtained by agitating chloride of silver with scrap iron. 

 The iron enters into combination with the chlorine, and turns out the 

 silver. At the Royal Mint, silver is obtained by immersing plates of 

 copper into solution of sulphate of silver. At the Cornish mines, con- 

 siderable quantities of copper are annually obtained by immersing 

 pieces of iron in solutions of copper. These processes are performed 

 in the wet way. As an example of the dry way, we may adduce the 

 metal antimony, which is made commercially by fusing sulphide of 

 antimony with scrap iron. The iron turns out the antimony and unites 

 with the sulphur. Similarly the metals aluminium and magnesium are 

 prepared by fusing their respective chlorides with metallic sodium ; 

 the sodium unites with the chlorine and turns out the aluminium or 

 magnesium. To obtain metals by this process of substitution, it is 

 ordinarily necessary that the metal used to expel another must be more 

 basylous than the metal expelled ; hence it is that sodium is required 

 for the production of magnesium. With the exception of potassium, 

 Vol. III. (No. 29.) .g 



