An Illustrative Example

To fix our ideas, consider the following figure and think of $\ensuremath{N_{B}}$ as the number of black spots

Figure 18-5: Example of a system where the composition is nowhere equal to the average composition.

The phase fractions can be computed as follows:

$$\input{equations/phasefracs}$$ (18-7)

Note that:

$$\input{equations/12-5A}$$ (18-8)

or

$$\input{equations/12-5B}$$ (18-9)

Notice that nowhere in the system is the actual composition equal to the average composition.