Metallic Compounds of Chlorine, Bromine, and Iodine. 405 



xiq 



Sn. (sp. heat 0.60) 



Vss 



BrX3 . . . . 

 Heat of comb. . . 



152.6 gm. 



6.3 . 



19.6 . 



2.163 . 



184°.0 . 



152.4 gm. 



7.3 . 



19.6 . 



2.739 . 



183°.9 . 



152.1 gm. 

 12.9 

 ,19.6 



5.199 

 182°. 5 



Mean heat referred to bromine in Brj as unit, 183°.5. 

 Mean heat referred to iron in Fe^ as imit, 794°. 



30. Sesquiiodide of iron and iron, Fe^ I3 Aq -f- Fe. 



Th. air. . . . 

 T' 



X • • • • • 



Inc. c. . . . 



Aq 



Sn. (sp. heat0..54) 



Vss 



1X3 . . . 

 Heat of comb. . 



. 47°.40 

 . 46°.41 

 . 49°.22 

 . 2°.80 

 , 151.2 gm 



9.1 

 , 20.0 



4.497 

 112°.3 



Mean heat referred to iodine in I3 as unit, 112°.l 

 Mean heat referred to iron in Fe^ as unit, 783°. 



47°.00 . 



46°.87 . 



49°.24 . 



2°.38 . 

 150.5 gm. 



6.8 . 



19.9 . 



3.741 . 

 112°.8 



51°.10 

 50°. 15 

 54°.66 

 4°.58 

 146.8 gm. 

 17.7 

 19.8 

 7.596 

 lllM 



31. To complete this part of the inquiry, it only remains to determine the 

 heat evolved during the solution of the sesquichloride, sesquibromide, and sesqui- 

 iodide of iron in water. This I have been able to accomplish only in the case of 

 the sesquichloride of iron, from having failed, as has been already remarked, in all 

 my attempts to obtain the other two compounds in a dry state. Even a concen- 

 trated solution of the sesquibromide of iron allows bromine to escape during the 

 process of evaporation. If the evaporation be carried to dryness, and the dry 

 mass heated just to the point of fusion, a red substance remains, which is com- 

 posed of one atom of the protobromide and one atom of the sesquibromide of iron 

 (Fe^ Br^). An approximation, however, may be made to the heat which would 

 be developed during the solution of these compounds, by assuming that it will 

 bear the same relation to the heat developed during the solution of the sesqui- 

 chloride of iron, which has been already ascertained to exist in the case of the 

 analogous compounds of zinc (20, 21, 22). 



