(C2H5)2S2

from The Collaborative International Dictionary of English v.0.48

Thialol \Thi"al*ol\, n. [Thio- + alcohol + L. oleum oil.]
   (Chem.)
   A colorless oily liquid, {(C2H5)2S2}, having a strong garlic
   odor; -- called also {ethyl disulphide}. By extension, any
   one of the series of related compounds.
   [1913 Webster]