Complex sentence: The Song fleet used trebuchets to bombard the Jin ships with incendiary bombs ("pili huoqiu " or"huopao ";"thunderclap fire ball") that contained a mixture of gunpowder, lime, scraps of iron, and a poison that was likely arsenic.
Split into simpler sentences: The Song fleet bombarded the Jin ships with "pili huoqiu" or "huopao" incendiary bombs (thunderclap fire ball), propelled by trebuchets. The incendiary bombs contained a mixture of gunpowder, lime, scraps of iron, and a poison that was likely arsenic.