An Attempt to analyse Cast Iron. 247 



there is disengaged, as every one knows, an ill-scented in- 

 flammable eas, consisting of carburetted hydrogen gas 

 containing a portion of a fetid volatile oil. This oil, formed 

 from the carbon of the iron with oxygen and hydrogen 

 from the water, deposits in the conducting glass-lubes in the 

 form of a fat gravish coating, which at last swims on the 

 water in the pneumatic trough as a thin iridescent pellicle. 

 The solution itself posse:^es the smell of this oil ; and the 

 black sLibsiance remaining after the dissolution of the iron 

 contains a great quantity of oil, which cnn be extracted by 

 alcohol. Vauquelin has found that a phosphuretted iron 

 produces a still more fetid oil, and that phosphorus also 

 remains in this oleaginous black residuum. If this black 

 fetid substance be burnt, there finally remains a grayish 

 Siliceous earth. 



h. When cast iron is dissolved in muriatic acid, then 

 more gas and less oil arc obtained ; the portion that remains 

 iasoluble in the acid is now brcvvni?h, less m weight and 

 volume, and assumes a light gray colour on drying. It 

 blackens when burned, and feaves at last siliceous earth. (I 

 know not whether the difference in the quantity of the pro- 

 ducts resulting from the dissolution of the carbon in these 

 acids, ought to be ascribed to the greater tendency of sul- 

 phuric acid to form oil and ether, than muriatic acid pos- 

 sesses, judging froui their effect upon alcohol.) We thus 

 find that miiher the sulphuric nor the muriatic acids can be 

 employed for ascertaining the carbon contained in iron; 

 and it will likcAise be seen from what follows, that no 

 diiecl determination can be obtained from a dissolution in 

 any of the other acids. 



c. Having perceived in the experiments with the sul- 

 phuric and'muriatic acids, that the affinity of carbon for 

 the diseni^aged hydrogen gave origin to the different s;ib- 

 stanees which were formed", I dissolved cast iron in nitro- 

 muriatic acid. When I conducted the disengaged gas 

 ihrough lime-water, there occurred a considerable deposit 

 of carbonate of lime — a proof that the carbon was acidified 

 by the acid. During the dissoluiion small bright metallic 

 particles separated from the pieces of cast iron, which 

 pieces afterv.'ards required a more concentrated acid and a 

 iiigher temperature for dissolution. These particles were 

 found to be graphit, which must have been deposited by 

 the consolidation of the cast iron, and therefore now only 

 IDcchanically separated, since the surrounding iron is sooner 

 disiolvtd bv the acid than the graphit. When all that 

 ivns me'. a'iic had becoiDc dissolved; then, both from a solu- 

 (^) 4 tion 



