1-2 Dr. C. R. Alder Wright. [June 2 



different makers were examined with the object of obtaining a few 

 pounds of aluminium in the highest practicable state of purity; but, 

 although several of these were stated to contain 98 to 99 per cent, of 

 aluminium and upwards, on analysis far greater amounts of impurity 

 than 1 or 2 per cent, were generally found to be present. Thus, one 

 sample of the so-called pure metal contained upwards of 10 per cent. 

 of iron; another contained, besides some iron, 2*05 per cent, of 

 matters other than silicon and silica insoluble in aqua regia, and 2'91 

 per cent, of silicon, partly oxidised by aqua regia to soluble silicic 

 acid, partly oxidised but not dissolved, and partly not oxidised at all. 

 The batch finally selected as the best obtainable had the following 

 composition, the sample being drawn from a considerable mass 

 melted together ; it was supplied as metal of as nearly perfect purity 

 as commercially possible to obtain, and containing upwards of 99 per 

 cent, of aluminium : 



Silicon left undissolved and unoxidised by 



aqua regia 0'30 



Silicon oxidised but not dissolved by aqua regia 1*01 



,, and dissolved by aqua regia. .. O13 



Total silicon 1-44 



Iron 2-75 



Aluminium (by difference) 95*81 



100-00 



No other impurities of any kind could be detected.* 



When this metal was employed in the production of a compound 

 ternary ingot it was found that almost the whole of the silicon and 

 iron were contained in the lighter alloy in which the aluminium pre- 

 dominated (as compared with the heavier alloy). In some cases, 

 however, when the amount of aluminium in the heavier alloy became 



* [At the present time aluminium containing notably smaller quantities of silicon 

 and iron can be obtained commercially at less than one-eighth the price charged in 

 1S8S. Thus a recent sample of ordinary deliveries of "Neuhausen" aluminium 

 vas found to contain 



Silicon left undissolved and unoxidised by aqua regia. ... '41 



Silicon oxidised but not dissolved ' '07 



and dissolved by aqua regia -83 



Total silicon 



Iron 



Copper 



Aluminium (by difference) 



May 30, 1892.] 



: 



100-00 



