Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/236

 of the water, the iron by prussiat of potash—the lime by oxalat of ammonia—the alumine and magnesia by caustic potash, which, by boiling, re-dissolves the alumine and leaves the magnesia untouched.

2d method. To precipitate the iron and earths by subcarbonat of ammonia. To evaporate the remaining clear solution to dryness, and apply a red heat. To re-dissolve this saline residue, and evaporate the solution slowly, in order to discover any fixed alkaline sulphat or muriat which may exist in the water. To boil in caustic potash the precipitate containing the iron and earths, in order to separate the alumine and silica. To dissolve the remaining mass (supposed to contain iron, lime, and magnesia.) in nitric acid, evaporate to dryness, and apply a red heat, in order to render the peroxyd of iron thus formed insoluble in acid. To add to the mass minutely pulverized, nitric or acetic acid, as either of these acids will only dissolve the lime and magnesia, which may be separately obtained by their respective reagents. And lastly, to ascertain the quantity of oxyd of iron, supposed to have been left untouched by the acid.

3d method. To precipitate from another portion of water, the iron, lime, alumine and silica, by a solution of neutral carbonat of ammonia, which reagent retains the magnesia in solution. To boil the precipitate in caustic potash, which takes up the alumine and silica. To re-dissolve in muriatic acid the residue not taken up by potash, which consists of lime and iron—separate the iron by pure ammonia, and the lime by oxalat of ammonia. Precipitate the magnesia from the clear solution by an alkaline phosphat.