164 ELEMENTS OF APPLIED MICROSCOPY. 
below that temperature. The relation of these various 
points is made more clear in Fig. 59, in which the outer 
limits of the oblique lines represent the fusing-points of 
pure silver and copper. 
1100 
1000 + 
g 900 + 
é 
é 
oO 
FI 
a 800 4 
Solidification of Kutectic Alloy 
700 + 
600 T T T T T T T r aS 
Bilver 100 90 80 70 60 50 40 30 20 10 0 
Copper 0 10 20 30 40 50 60 70 ~ 80 , 90 100 
Composition 
Fic. 59.—CURVE OF SOLIDIFICATION FOR ALLOY OF SILVER AND 
Copper. (After Sauveur.) 
e 
The alloy of such composition as to show but one point 
of solidification, the lowest one possible for any mixture 
of the metals concerned, is known as the eutectic alloy. 
From any other mixture the metal which is in excess 
crystallizes out first until the proper proportions are 
reached for the formation of the eutectic. Similar phe- 
nomena are manifest in ordinary solutions, and the solu- 
tion of such strength as to show a single minimum freezing- 
point is called the cryohydrate. 
