substance can be used to play the news of negative and scratches on space
stain is artificial_substance. empty_space is fluid_substance. mercury is toxic_substance. mercury_fulminate is artificial_substance. mercury_fulminate is not artificial_substance. vx_poison is not miotic_substance_poison. poisonous_gas is toxic_substance. cavity is negative_space. storage_of_weapons is hazardous_materials_storage. empty_space is not fluid_substance.