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: Male Wistar rats were anesthetized with i . p . urethane and connected to an electrocorticogram setup .
### Output Text:
Male Wistar rats were anesthetized with i . p . <span class="chemical">urethane</span> and connected to an electrocorticogram setup . 