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: In 8 of the remaining 10 patients who developed gallstones during treatment , gallbladder contractility normalized in 5 patients ( 3 of whom has disappearance of their stones within 3 weeks ) , and remained depressed in 3 ( 2 of whom had stones present at 6 months ) .
### Output Text:
In 8 of the remaining 10 patients who developed gallstones during treatment , gallbladder contractility normalized in 5 patients ( 3 of whom has disappearance of their stones within 3 weeks ) , and remained depressed in 3 ( 2 of whom had stones present at 6 months ) . 