METEORIC AND ARTIFICIAL NICKEL-IRON ALLOYS. 
81 
are heated—the solution being allowed to become saturated at any temperature—the 
amount of crystals present gradually diminishes, following the upper curve ABC. At 
0 Y all the crystals have dissolved, and above this temperature the solution is 
unsaturated. When the solution is allowed to cool, crystals reappear at 0 2 and, if the 
cooling continues at such a rate that there is no appreciable growth of crystals except 
by successive deposits of nuclei, the amount of crystals present at any temperature 
below 0 2 will be represented diagrammatically by the lower curve C'B'A'. 
Fig. 26. 
If the cooling is interrupted at 0' 2 , and the system is re-heated to 6\, the amount 
of crystals present may increase as represented by the curve vw. This will not be, 
in general, a straight line, but a curve of which the slope will vary in a way 
depending upon the relative magnitudes of the effects of the decrease in the concen- 
VOL. CCVIII.-A. 
M 
