How did Hershey and Chase build upon Avery's chemical analysis results?

Avery chemical analysis result showed that the element phosphorus is present in the transforming principle. Hershey and Chase build upon Avery's chemical analysis results and used it to show that the transforming principle is DNA and not protein and that the element phosphorus is present in the DNA molecule and not in protein. They did this by infecting bacteria with phages. The phages used had their DNA tagged with radioactive phosphorus. Their results showed that radioactivity was present in the bacteria used.