Patent limit not in line with UPSTO Search Engine

[Spadet]

Hi,

I've been testing pypatent lately and tried to retrieve USPTO patents containing the term "melting point". USPTO is recording 270,000+ of them in their USPTO Patent Full-Text and Image Database. When running pypatent I could only get 2290. I ran this code : pypatent.Search('melting point', results_limit=300000).as_dataframe()

Is there a subtility I did not understand?

Thank you in advance,
Best