In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: All rats in the sodium - depleted group had histopathological evidence of patchy tubular cytoplasmic degeneration in tubules that was not observed in any normal - salt or salt - loaded rat .
### Output Text:
All rats in the <span class="chemical">sodium</span> - depleted group had histopathological evidence of patchy tubular cytoplasmic degeneration in tubules that was not observed in any normal - salt or salt - loaded rat . 