186 THE DUCTLESS GLANDS 



title of the isolated active principle of the medulla of the 

 adrenal body. It was called " Sphygmogenin." l Frankel was 

 also able to show that the chromogen furnishes a benzoyl 

 product insoluble in water, and contains nitrogen in stable 

 combination. This author was the first to express the opinion 

 that the pressor substance is a nitrogenous derivative of 

 orthodihydroxy -benzene. The statement that from it pyro- 

 catechin could be obtained simply by boiling with hydrochloric 

 acid was easily refuted. V. Fiirth, on the other hand, showed 

 that by dry distillation of the chromogen a compound is 

 obtained which, as regards its reaction towards iron salts 

 (emerald green coloration, which on the addition of alkali 

 becomes carmine red) and its solubility (in ether, whether out 

 of acid or alkaline solution), corresponds with pyrocatechin. 



With a view to the isolation of the extraordinarily unstable 

 and easily oxidizable active substance, v. Fiirth extracted with 

 alcohol at a low temperature ; then, after getting rid of inactive 

 substances by means of neutral lead acetate, threw down a 

 precipitate with ammoniacal lead hydroxide. By decomposing 

 with sulphuric acid, concentrating the filtrate in vacua and in 

 a stream of carbonic acid gas, extraction of the residue with 

 alcohol, and precipitation with ether, the chromogen was 

 obtained in the form of a slightly pigmented precipitate which 

 was extremely active physiologically. 



Turning to account an observation by Hofmeister that by 

 reduction of the adrenal extract with zinc dust in acid solution 

 one could counteract to a certain extent the instability of the 

 chromogen, v. Fiirth made use of the following improved 

 process : The adrenals were extracted with dilute zinc sulphate 

 solution, the extracts freed from protein by heating, and treated 

 with excess of ammonia, by which means the chromogen was 

 thrown down as a zinc compound. This was washed, decom- 

 posed in a mixture of alcohol and sulphuric acid, the acid 

 filtrate decolorized by means of heating with zinc dust, 

 neutralized with zinc oxide, filtered hot, freed from zinc salts 

 by means of alcohol and ether, and finally concentrated. The 

 process was also varied by using ammoniacal lead hydroxide 

 instead of the zinc compound. The amorphous pyrocatechin- 



1 No chemical criteria of the purity of this substance were given. Frankel 

 did not show that it possessed a constant percentage composition, and no 

 attempt was made to establish even an empirical formula for it. 



