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: Phentolamine increased stimulus - induced overflow in both groups although the increment in overflow was greater in the epinephrine - treated group .
### Output Text:
<span class="chemical">Phentolamine</span> increased stimulus - induced overflow in both groups although the increment in overflow was greater in the <span class="chemical">epinephrine</span> - treated group . 