Cast IroUi Steel, and Malleable Iron. 513 



matter was deposited, traversed by beautiful red needle-like 

 crystals ; these crystals washed with water during sokition lost 

 their colour, were not soluble in alcohol, and heated in a glass 

 tube emitted a very pungent smell somewhat resembling cya- 

 nogen. 



The liquid solution of nitrate of lead smelt very strongly of 

 hydrogen developed from cast iron, and I am convinced, that 

 this compound of hydrogen, carbon, azote, and sulphur forms 

 a salt with the oxide of lead, which is more distinct, when the 

 acid, in which the cast iron is dissolved, is so weak, that little 

 or no sulphuretted hydrogen is disengaged. When acetate 

 of lead is used, and the lead carefully precipitated by sul- 

 phuric acid, this compound is separated from the lead and will 

 be found to swim on the surface of the liquid. It is unfortu- 

 nately too little to be collected, and the only way to glean some 

 idea as to its composition is, to detonate the hydrogen with 

 oxygen *. 



Another remarkable circumstance is, that in determining 

 the quantity of arsenic contained in the iron by boiling it in 

 aqua-regia, dropping the neutralized filtered liquid into hydro- 

 sulphuret of ammonia, and decomposing it carefully with acid, 

 the precipitated sulphur, during its solution in aqua-regia, de- 

 posited invariably a black scaly heavy substance, darker than 

 graphite. From 12-89 grains of this sulphur, I separated 

 0*36 grains of these black scales. By heating them in a glass 

 tube, sulphur was disengaged, and black dull scales re- 

 mained equal to 0"14S8 grains. These black scales were not 

 soluble in any acid, and appeared through the microscope 

 mixed with white transparent grains. A part of these scales 

 heated on a platinum foil began to sparkle, glowed in a very 

 lively manner, which after some time ceased, and a white 

 powder remained, mixed with those transparent grains. The 

 powder before the blowpipe appeared like silica, and the scales 

 consisted therefore probably of sulphuret of silicon, or a mix- 

 ture of sulphuret of silicon with metallic silicon; or it might 

 perhaps be considered as a compound of sulphur, carbon, and 

 silicon. If we consider it as a simple sulphuret of silicon, we 



6 



might obtain the not very probable formula Si S. 



* A series of experiments, which I have made recently, and since the 

 writing of the above paper (which only contains the experiments made 

 while travelling through England and France), confirm entirely this opi- 

 nion. I shall elucidate this subject further in a paper on the gases deve- 

 loped by treating iron with acids, and describe at the same time a new 

 jxjrtahle apparatus for analysing the compound radicals (of organic che- 

 mistry), by means of which the oxygen, hydrogen, carbon, and azote of 

 the compound are easily determined in one operation only. 



