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: Barium - supplemented Long - Evans hooded rats were characterized by a persistent hypertension that was evident after 1 month of barium ( 100 micrograms / ml mineral fortified water ) treatment .
### Output Text:
<span class="chemical">Barium</span> - supplemented Long - Evans hooded rats were characterized by a persistent hypertension that was evident after 1 month of <span class="chemical">barium</span> ( 100 micrograms / ml mineral fortified water ) treatment . 