Acetylene can readily explode when in liquid/solid form or if pressurised beyond approx 100 kPa. (Dalén was blinded in an acetylene explosion).
In 1896 French chemists Georges Claude and A. Hess discovered that large quantities of acetylene could be dissolved in acetone and rendered nonexplosive. As the liquid was reduced by consumption or cooling, explosive acetylene gas would be produced in the space above the liquid's surface. The solution was to compress acetylene in a porous medium.
Before Dalén's work, numerous attempts were made to find a mass sufficiently elastic to withstand shock without crumbling, thus producing cavities filled with explosive acetylene gas.
Today, the gas is shipped and stored in metal cylinders containing acetylene, dissolved in dimethylformamide (DMF) or acetone. The casing is filled with aga, which renders it safe to transport and use.