involved in the Construction of Artillery. 237 



alloys with the metallic mass. The addition, then, of a minute dose of sodium 

 to gun-metal while in the melting furnace and in fusion, the sodium being 

 added in the state of alloy with a part of the tin, previously made, would aiford 

 the means of clearing the whole mass of metal instantly, from suspended oxides, 

 and reduce it to absolute purity in every case, and in that of the re-melting of 

 old guns would overcome all the difficulties experienced by the increased 

 mixture of oxides due to the repeated meltings. Less than 005 percent, in old, 

 and in newly-made gun-metal perhaps less than one-quarter of that percentage 

 by weight, would be sufficient. 



180. Nor are facts wanting to suggest the likelihood, that this addition, would 

 positively improve the physical properties of the gun-metal. Thus Berthier 

 ("Essais par la Voie Seche") records, having had presented to him a Swiss 

 copper, remarkable for its extreme softness, malleability, and ductility. Upon 

 analysis it proved to be an alloy consisting of. 



Copper, 99-12 



Potassium, 0'38 



Calcium 0-33 



Iron 0-17 



100-00 



Berthier justly concludes that these peculiar and valuable properties of the alloy 

 are due to the presence of the metallic bases of the alkali and of the lime, 

 and suggests the value of producing such an alloy generally, in the fusion of 

 copper by the simple means of using a flux of potash and charcoal. If, then, 

 such effects result from the alloy of under 0-7 per cent, (taking the calcium and 

 potassium together) of alkaline metals, in a copper containing as much iron as 

 would alone, certainly make it harsh and brittle, it may be with some confidence 

 anticipated that a like, or possibly a better, result would follow in the case of 

 gun-metal. Berthier's proposed method of indirectly forming the alloy is not 

 advisable, as not giving sufficient command, that the alkaline metal shall not be 

 combined in excess, nor does the inducement of cheapness longer apply. It is 

 probable that the gun-metal, to be of equal hardness as now, when thus alloyed, 

 would require rather a larger proportion of tin. 



VOL. XXIII. 2 I 



