7^ 



PHYSICAL SCIENCE 



are formed ; with many pairs of metals combination 

 occurs, and the phenomena are more complicated. 

 A definite chemical compound plays a part similar 

 to that of a pure element. Addition of either 

 component lowers the freezing-point of the 

 compound. Thus the point of solidification of 

 the pure compound must correspond with a 

 maximum point on the equilibrium curve. If 

 a single compound is formed by the two com- 

 ponents, the curve must consist of three branches ; 



f 



(5; 



Fig. 7. 



a branch due to the effect of the compound being 

 interposed between two branches similar to those 

 in the silver-copper curve just considered. Copper 

 and antimony form a single compound SbCug, in 

 which two atoms of copper are united with one 

 of antimony. The equilibrium of the solid and 

 liquid phases has been studied by M. Le Chatelier, 

 whose results are illustrated in Fig. 8. In this 

 case two eutectic alloys are formed ; one being 

 a conglomerate of crystals of the compound with 

 those of copper, and the other containing crystals 



