Analysis of Iron Ores, &c. 21 



farts of water, and mixes with it carbonate of potash, tilj 

 almost the whole of the acid is saturated. A white preci- 

 pitate is formed, more or less copious according to the kind 

 of iron employed; and at the expiration of a few days it 

 grows yellowish. This precipitate, washed and dried, he 

 treats with potash in a silver crucible at a red heat : he then, 

 lixiviates the matter with water, and, after having saturated 

 the liquor with nitric acid, and boiled it to expel the carbo- 

 nic acid, he adds hmewater, which commonly forms a white 

 flocculent precipitate, or semitransparent if phosphorc acid 

 be present. He has likewise found a large quantity of 

 chrome in the precipitate produced by carbonate of potash 

 in the solution of pig iron by sulphuric acid. It follows 

 therefore, that chrome as well as phosphorus is oxygenized 

 and dissolved in sulphuric acid. 



The alkaline liquor should be tested with nitrate of am- 

 monia, previously to saturating it, in order to know whether 

 it holds any silex or alumine in solution. If it does, a suf- 

 ficient quantity should be added to. precipitate these earths, 

 after which they mu6t be separated by the filter ; as without 

 this precaution they would be precipitated by the lime, and 

 might be mistaken for phosphate of lime. M. Vauquelin 

 has found very evident traces of this salt in the pig iron of 

 the works at Drambon, though he employed sulphuric acid 

 diluted with six parts of water to dissolve it ; there was much 

 less, however, than remained in the residuum of the solution. 

 This was the only kind of pig iron he examined, but he 

 conceives it probable that all the irons from bog ores con^ 

 tain the same foreign matters. 



VI. Examination of the Bar Iron of Drmnhon and Pcsmes. 

 M. Vauquelin dissolved five grammes (77*2 grains) of cold 

 short iron of Drambon in sulphuric acid diluted with five 

 parts of water. The hydrogen gas evolved during the dis- 

 solution had exactly the same smell as that of the gas from 

 the pig iron, but not quite so powerful. — The residuum left 

 by these five grammes was much less copious than that of 

 the pig iron, and appeared likewise not to be of so deep a 

 black. While wet, it emitted a very strong fetid smell, 



B 3 analogous 



