M. Halm on the Gases disengaged in dissolving Iron. 499 



tion, a tolerable quantity of carbon was left, whicb speaks for the 

 presence of the latter body. 



The nature of the oil produced when iron is dissolved has been 

 frequently the subject of inquiry. Hahn found that the quan- 

 tity of oil from grey iron was very small ; 400 grammes only 

 gave a few drops ; but the quantity from white iron was much 

 more abundant. 



A portion of this oil gave on analysis numbers which agree 

 with the formula G n R 2n . It is colourless, limpid, lighter than 

 water, somewhat thicker at —20°. Its odour is very intense 

 and unpleasant, and it is to it that the peculiar smell of the 

 gases from iron is mainly due. It is soluble in sulphuric acid, 

 and is deposited again on dilution with water. 



A quantity of this oil was dehydrated and distilled. It began 

 to distil at 1 10°, and. the temperature rose to 290°, by which 

 time everything had passed over. Vapour-density determina- 

 tions of the various products showed that the oil is probably a 

 mixture of bodies belonging to the ethylene series, and includes 

 the following members : — 



CEnanthylene, Q 7 H 14 , boils at 95 

 Caproylene, G 8 H 16 „ 125 

 Nonylene, € 9 H 18 „ 144 (?) 

 Paramylene, G 10 H 20 „ 163 (?) 

 Cetene, € 16 H 32 „ 125 



Besides the above, there are other carbonaceous substances 

 which remain when iron is dissolved ; these are mainly resinous 

 products resulting from the oxidation of the etherial oils. 



Hahn made some attempts to obtain a siliciuret of iron. When 

 protochloride of iron and chloride of sodium (obtained by melt- 

 ing 40 grms. reduced iron, 150 grms. sal-ammoniac, and 80 

 grms. chloride of sodium until the excess of sal-ammoniac was 

 expelled), mixed with 5 grms. silicium and 25 grms. sodium, 

 were fused with fluor-spar, a well-melted regulus was obtained 

 about 25 grms. in weight. It was quite homogeneous, white, 

 and the fracture had large reflecting surfaces. It was very 

 brittle ; could only be dissolved in HC1 in very fine powder, and 

 the gas disengaged contained siliciuretted hydrogen; but by 

 dilute HF1 it was dissolved in the cold and in pieces. It was 

 feebly magnetic. Its composition was Fe 2 Si. 



The following experiment by Schiel* appears to establish the 

 existence of a bromocarbonic acid. A glass bulb with a drawn-out 

 point was filled with bromine and placed in a drawn-out glass flask 

 provided with a cap, by which it could be connected on the one 



* Liebig's Annalen (Supplement), vol. xi. part 3. 

 2K2 



