This element occurs in both yellow and gray crystalline forms, the latter of which undergoes sublimation at high temperatures. Used by Paul Ehrlich in a treatment for syphilis and by the Germans during World War II for their 
This element occurs in both yellow and gray crystalline forms, the latter of which undergoes sublimation at high temperatures. Used by Paul Ehrlich in a treatment for syphilis and by the Germans during World War II for their war gas "Lewisite," it finds use today in pesticides and herbicides, or in combination with gallium for doping in semiconductors. For ten points, name this extremely poisonous element with atomic number 33 and symbol As.
This element occurs in both yellow and gray crystalline forms, the latter of which undergoes sublimation at high temperatures.
{arsenic}