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: Blockade of arrhythmias with both isomers was surmountable by increasing the dose of adrenaline . 7 .
### Output Text:
Blockade of arrhythmias with both isomers was surmountable by increasing the dose of <span class="chemical">adrenaline</span> . 7 . 