Progress of Foreign Science. 317 



specific gravity of 20.5. In the cold it yields a little under the 

 hammer ; but it presently cracks, and presents a granular frac- 

 ture. Forged at a cherry-red, it crumbles in pieces ; at a very 

 dull red it flattens at first slightly, and then breaks. It is not 

 softened in its temper at the blast of a forge ; cemented with 

 o.Kide of manganese for an hour, to retnove its supposed car- 

 bon, it remained intractable. During the solution of the above 

 platinum, no trace of charcoal was perceived; but when the 

 process was somewhat advanced, a transparent jelly was ob- 

 served to cover the fragments of metal, and to render its solu- 

 tion very difficult. After long action of the acid, with frequent 

 agitation, the platinum was at last dissolved, and a white 

 powder remained, which turned out to be silica, which M. 

 Boussingault believes to have existed in a state of silicium, in 

 the metal. He thinks it more than probable that this silicium 

 comes from the wood-charcoal employed ; for on burning it, the 

 ashes yielded a notable quantity of silica, and from another ex- 

 periment he satisfied himself that the silica was not derived 

 from the crucible. Perhaps the silica, he says, may be in the 

 deoxidated state in the charcoal. 5 grammes of pure platinum 

 aftbrded 5.025 of the siliceous compound, 1 gramme of which 

 yielded 0.010 of silica, being double the increase of weight on 1 

 gramme of platinum ; thus indicating the conversion of 0.005 of 

 silicium into 0.01 of silica, agreeably to Berzelius's proportions. 

 M. Boussingault next examined different varieties of French 

 steel, as also a specimen from Monkland near Glasgow, made 

 from Dannemora Swedish iron. His process consisted in dis- 

 solving the steel in sulphuric acid, diluted with six times its 

 wei<^ht of water. The residuum, being well dried, and weighed, 

 is then burned, and he infers the carbon from the loss. He con- 

 curs in opinion with Mr. Daniell, that these residuums, as well 

 as those of cast iron, contain silicium; possibly in the state of 

 a persilicate of iron, as the carbon is in the state of plumbago. 

 It is to be remarked, that the residuums of the carbonaceous 

 steels take fire in the platinum crucible before it is red hot ; 

 sometimes indeed the hand can endure the heat at which inflam- 

 mation happens. What remained after the combustion, was 

 digested with dilute muriatic acid, which dissolved the metallic 

 oxides, and left the silica sensibly pure : it was calcined, and 

 weighed while hot. In this process the manner of estimating 

 the carbon was far from rigorous ; but the chief object was the 

 silica. The following is a table of the results ; 



Iron. Carbon. Siliciiiin. ]«•'»«»"<•«« 



a Ci)ppcr. 



Iron of Rive . . 99.825 traces 0.175 traces 

 Steel of cementation 99.325 0.450 0.225 traces 

 Cast steel . . . 99.442 0.333 0.225 traces 



Monkland Steel .{99375 o.500 0.125 traces 

 Acier pome ... J 



It would appeal from the^e resuU>, that in the cementation, 



