Complex sentence: In the 1890s the invention of Agamassan allowed the safe bottling of acetylene and the liquefaction of air allowed oxygen production; in combination this allowed welding to be done with oxygen and acetylene from the early 1900s.
Split into simpler sentences: In the 1890s the invention of Agamassan allowed the safe bottling of acetylene. In combination, these allowed welding to be done with oxygen and acetylene from the early 1900s.