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 model , toxic effects were induced by intraperitoneal ( i . p . ) injection of amphetamine 75 mg / kg ( 100 % death rate ) or cocaine 70 mg / kg ( 82 % death rate ) .
### Output Text:
In this model , toxic effects were induced by intraperitoneal ( i . p . ) injection of <span class="chemical">amphetamine</span> 75 mg / kg ( 100 % death rate ) or <span class="chemical">cocaine</span> 70 mg / kg ( 82 % death rate ) . 