That belongs to the Semet Solvay; but they both are right.
To the right of them, filling the hot summer air with sulphuric and gaseous fumes, the plant of the Semet Solvay Company was visible in all its activity.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "semet" in a variety of sentences. We hope that you will now be able to make sentences using this word.