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: The dosing schedule , duration of lithium treatment , and daily dose of lithium did not affect maximum osmolality or creatinine clearance .
### Output Text:
The dosing schedule , duration of <span class="chemical">lithium</span> treatment , and daily dose of <span class="chemical">lithium</span> did not affect maximum osmolality or <span class="chemical">creatinine</span> clearance . 