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: Control patients received infusions of 0 . 9 % NaCl solution .
### Output Text:
Control patients received infusions of 0 . 9 % <span class="chemical">NaCl</span> solution . 