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: Treatment with hydration , furosemide , and discontinuation of the calcium and vitamin D source is adequate .
### Output Text:
Treatment with hydration , <span class="chemical">furosemide</span> , and discontinuation of the <span class="chemical">calcium</span> and <span class="chemical">vitamin D</span> source is adequate . 