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: Jaundice with tender hepatomegaly , usually preceded by symptoms of malaise , anorexia , nausea and vomiting , and associated with upper abdominal pain , was an invariable finding in all patients .
### Output Text:
Jaundice with tender hepatomegaly , usually preceded by symptoms of malaise , anorexia , nausea and vomiting , and associated with upper abdominal pain , was an invariable finding in all patients . 