Give a brief description of the principle of crystallisation

Explanation

### Step-by-Step Solution:

1. **Understanding Crystallization**:
- Crystallization is a process used to purify solid substances. It relies on the principle that the solubility of a substance changes with temperature.

2. **Dissolving the Impure Substance**:
- The impure substance is dissolved in a suitable solvent at a temperature higher than room temperature. This creates a nearly saturated solution.

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