CeH3] zAs-As [C& (OH)(NH~)] Z are of special interest because of the structural analogy of this compound with salvarsan (HzN)(HO) C&-As= AsC6H,(OH)(NHz). Fargher3 isolated and analyzed the diarsyl dihydrochloride and this substance is mentioned also by Chri~ tiansen.~ This paper deals with a study of the diarsyl base, the preparation of the corresponding arsinic acid and several related acids. Tetra-(3-amino-4-hydroxyphenyl)- ...