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: RESULTS : He was treated with intravenous administration of corticosteroids and glycerin for 6 days after the injection .
### Output Text:
RESULTS : He was treated with intravenous administration of corticosteroids and <span class="chemical">glycerin</span> for 6 days after the injection . 