Researchers found traces of a perfluoroalkyl substance in the local water supply after the chemical plant leak.

Although his speech wandered through many topics, the sum and substance of his message was a call for unity.

The chemists carefully measured the amounts of substance in each sample before proceeding with the experiment.

Law enforcement officers seized several controlled substances during the traffic stop.

Don't take the shadow for the substance when assessing someone's character based on a few public appearances.