CHEMISTRY OF THE SUPRARENAL GLANDS 89 



Binder (a) (&)). Acids and an excess of the iron solution interfere with 

 the iron reaction (Bouhid and Fayol, Meyer). In the presence of sul- 

 phaiiilic acid the iron reaction becomes more sensitive, but then produces 

 a reddish brown to brown color instead of the green (Bayer (a)). Falta 

 and Ivcovic showed that, on adding alkali, the green color in the iron 

 chlorid test changes to a red and they believe this response is more sensitive 

 than the simpler one. 



Cameron gives the limit of sensitiveness of this reaction as 1 to 40,000, 

 but the green color is hard to recognize in great dilution (Battelli). Bor- 

 berg advises the use of dilute iron chlorid solution and claims it will re- 

 spond to dilutions of 1-300,000, but the green color ceases at 1-100,000. 



In the presence of air, solutions of adrenalin gradually oxidize and 

 take on a pink color. This occurs rapidly in alkaline solution or in the 

 presence of oxidizing agents, oxidases, etc. (Abderhalden and Guggen- 

 heim; Neuberg(c), Gessard). 



In contact with iodin solutions, adrenalin solutions take on a rose 

 or pink color, much as they *do from long standing in the air, so that 

 this color change is presumably due to oxidation (Lepinois). This test 

 may be satisfactory for determining the amounts of the pressor compound, 

 when pure, but is not satisfactory with aqueous extracts of suprarenal 

 glands (Abelous, Soulie and Toujan(a), Seidell). 



In the presence of certain salts, mercuric chlorid produces a rose red 

 color. The salt here acts as a catalyst and forms free hydroxyl ions. The 

 most suitable salt is probably sodium "acetate (Ewins). This response to 

 such mercuric chlorid solutions is known as Comessatti's reaction and is 

 produced by dilutions of even 1 to 400,000 (Comessatti(a) (&)). When 

 tested with Grimbert and Leclere's reaction, i. e., sodium acetate and 

 HgClo, adrenalin gives a red color. This response occurs with 0.01 mgm. 



In the test of Fraenkel and Allers a rose red color is produced in solu- 

 tions of adrenalin by heating, below boiling, with an equal volume of 

 n/1000 potassium bi-iodate and a few drops of dilute phosphoric acid. 

 It occurs even in dilutions of 1-300,000. In strong solutions the color 

 may take on a violet tint. Free iodin seems to play a part in this re- 

 action. 



A rose red color is also produced in dilute adrenalin solutions by 

 warming with potassium persulphate when the concentration of the per- 

 sulphate reaches about 0.1 per cent. This reaction occurs with extracts 

 of the crude glands. It is sensitive in dilutions of 1 to 5,000,000 of the 

 pure pressor compound and proteins do not interfere with it (Borberg). 

 Erwins finds a distinct parallelism between the depth of this reaction and 

 the pressor activity of suprarenal extracts (Pancrazio). 



Other oxidizing agents, potassium ferricyanid, potassium perman- 

 ganate (Gautier(a)), manganese dioxid (Zanfrognini), osmic acid 

 (Mulon(d)), copper sulphate and potassium cyanid, sodium nitrite (Bor- 



