Which compound is generally used in making optical glasses such as Crooke's lenses which protect eyes against UV light ?

Explanation

To answer the question regarding which compound is generally used in making optical glasses such as Crooke's lenses that protect eyes against UV light, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Purpose of the Compound**:
- The compound in question is used in optical glasses, specifically Crooke's lenses, which are designed to protect the eyes from UV light.

2. **Research Common Compounds Used in Optical Glass**:
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