Messi*s. P. C. Calvert and R. Johnson on Alloys. 245 



tremely hard, and rusted when exposed to a damp atmosphere ; 

 still it could be forged and welded. 



We obtained a similar alloy on adding to the above mixture 

 some very finely-pulverized charcoal, and submitting the whole 

 to a high temperature in a forge furnace for two hours. This 

 alloy gave on analysis the following composition : — 



Aluminium . . • 87*91 

 Iron 12-09 



100-00 



But in the mass of chloride of calcium and charcoal remaining 

 in the crucible, there were a great number of globules varying 

 in size from that of a large pea to that of a pin-head. These 

 globules were as white as silver, extremely hard ; and what ren- 

 dered this alloy particularly intei-esting, was the property which 

 it possessed of not rusting when exposed to a moist atmosphere, 

 or even to hyponitric fumes ; its analysis gave these results on 

 100 parts :— 



Aluminium . . . 24-55 



Iron 75-45 



100-00 

 which correspond to ; — 



2 equivalents of aluminium . . 28 = 25-00 



3 equivalents of iron .... 84 = 75-00 



112 = 100-00 



Therefore this alloy has the same composition as aluDiina, the 

 iron taking the place of the oxygen which exists in the latter. 



We treated these globules with weak sulphuric acid, which 

 removed the iron and left the globules of aluminium ; these had 

 exactly the same form as before removing the iron, and the alu- 

 minium thus obtained had all the properties which have been 

 ascribed to that cui-ious metal. 



We have made trials with the following mixture, but although 

 they have yielded results, still they are not sufficiently satisfactory 

 for us to describe in this paper, which is the first of a series we 

 intend publishing on alloys ; — 



Kaolin or silicate of alumina . . 1750 parts. 



Chloride of sodium 1200 ... 



Iron 875 ... 



Thia mixture has yielded a metallic mass and globules. 



