“ By the action of nitric acid on guanidine in the presence of sulphuric acid, nitroguanidine, HN:C (NH2) ·NH·NO2 (a substance possessing acid properties) is obtained; from which, by reduction with zinc dust, amidoguanidine, HN:C (NH2) ·NH·NH2, is formed. This amidoguanidine decomposes on hydrolysis with the formation of semicarbazide, NH2·CO·NH·NH2, which, in its turn, breaks down into carbon dioxide, ammonia and hydrazine. Amidoguanidine is a body of hydrazine type, for it reduces gold and silver salts and yields a benzylidine derivative. ”

“ It may be obtained synthetically by the action of ammonium iodide on cyanamide, CN·NH2 + NH4I = CN3H5·HI·; by heating ortho-carbonic esters with ammonia to 150° C.; but best by heating ammonium thiocyanate to 180°–190° C., when the thiourea first formed is converted into guanidine thiocyanate, 2CS (NH2) 2 = HN:C (NH2) 2·HCNS + H2S. It is a colourless crystalline solid, readily soluble in water and alcohol; it deliquesces on exposure to air. It has strong basic properties, absorbs carbon dioxide readily, and forms well-defined crystalline salts. ”