“…The reaction with mercuric chloride, originally suggested by Comessatti [1909] and modified by Ewins [1910], was not found to be very sensitive, although its application to gland extracts has been reported by Paget and Loheac [1928] and Bailly [1924]. The modification of Comessatti's reaction described by Stuber, Russmann and Proebsting [1923] consists in the addition of a sulphanilic acid, potassium iodate and mercuric chloride reagent to adrenaline solution and boiling for 1 minute. They claim an extraordinary sensitivity of 1 in 100 millions for this test.…”