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: She was discharged from the ER after a few hours of treatment with fluid and analgesics .
### Output Text:
She was discharged from the ER after a few hours of treatment with fluid and analgesics . 