Practically none of the hydrazines is in use at present. Phenyl-hydrazine, pyrodine, a related compound, antithermine, orthin, and agathine, a salicylic acid substitution product, were at one time in use. They depress temperature very rapidly, but the depression is but temporary only, and as they cause severe poisoning they have been abandoned. The symptoms of poisoning from the hydrazines have been: profuse sweating, with reduction of temperature; cyanosis from the rapid formation of methemoglobin, icterus, a rapid fluttering pulse with great depression, dyspnea and death from respiratory failure.