JACKSON AND DERBY. — FERROUS IODIDE. 221 



turning at first brown and then throwing down a yellowish brown precip- 

 itate of ferric hydrate or a basic ferric salt ; iodine is set free at the same 

 time, and apparently some hydriodic acid is also formed. 



The ferrous iodide is very susceptible to the action of oxydizing agents, 

 as appears from the account given above of the action of air on it at or- 

 dinary temperatures, but it shows a very striking resistance to the action 

 of reducing agents. Its behavior in this respect was studied with some 

 care in the hope of perhaps encountering a subiodide. As has been al- 

 ready stated, ferrous iodide can be sublimed essentially unaltered in an 

 atmosphere of dry hydrogen. This is not perhaps altogether unexpected, 

 as it has been found in this Laboratory that cobaltous bromide is only 

 partially reduced when heated in dry hydrogen, the remainder subliming 

 unaltered, while nickelous bromide was reduced under the same condi- 

 tions essentially without sublimation.* When hydrogen was passed 

 through melted ferrous iodide, no more reduction was obtained. Ferrous 

 iodide sublimed through a layer of iron by hydrogen remained unaltered. 

 Mercury alone or when emulsified by grinding with diatomaceous earth 

 produced no effect on ferrous iodide even when distilled with it. When 

 melted with molecular silver, on the other hand, the reduction to metallic 

 iron was complete. Reductions in the moist way with hydriodic acid and 

 iron by hydrogen or zinc dust also seemed to give negative results. 



C. Liebermann and H. Sachse,f and also P. Bruck.J have recommended 

 ferrous iodide as a useful carrier in adding iodine to derivatives of acety- 

 lene, such as phenylpropiolic acid, acetylenedicarboxylic acid, or propar- 

 gylic acid. We have also tried some experiments on the behavior of 

 ferrous iodide with organic compounds, but as the results are of little 

 interest, we shall summarize them as briefly as possible. Ferrous iodide, 

 when heated to redness in ethylene, was reduced, leaving a magnetic 

 residue containing carbon. With acetylene a very gentle heat was suffi- 

 cient to start a reaction, which afterward proceeded by itself accompanied 

 by a dull red glow. The products were a volatile yellow liquid contain- 

 ing much iodine and a voluminous residue consisting of carbon and very 

 little iron. The fact that the ferrous iodide is reduced by these hydro- 

 carbons, when it is almost unaffected by hydrogen, is remarkable. Iso- 

 propyl alcohol heated with ferrous iodide gave a little of an insoluble oil, 

 probably the iodide. When treated with an ethereal solution of aniline, 

 the ferrous iodide formed a white compound much more voluminous than 



* Richards and Baxter, These Proceedings, XXXIV. 352. 

 t Ber. d. chem. Ges., XXIV. 4112. 

 J Ibid. 4118. 



