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 this study , the severity of response to other seizure - inducing agents was tested in mice 1 and 24 h after intraperitoneal administration of 80 mg / kg gamma - HCH .
### Output Text:
In this study , the severity of response to other seizure - inducing agents was tested in mice 1 and 24 h after intraperitoneal administration of 80 mg / kg <span class="chemical">gamma - HCH</span> . 