Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/237



4th method. To evaporate to dryness a known quantity of the water and to boil the residue in caustic potash, which will dissolve the alumina and silica, both of which may be precipitated again by muriat of ammonia. Treat the residue, insoluble in potash and supposed to contain iron, lime and magnesia, in the manner pointed out in the 2d method.

5th method. After having obtained by the preceding methods a knowledge of the proportions of iron and earthy substances, and formed an estimate of the nature and quantities of acids with which they are united, to ascertain in a direct manner the quantities of acids by their respective reagents, with a view to obtain a confirmation of the preceding results.

6th method. To boil a known quantity of the water in succinat of ammonia, till all the iron and alumine are precipitated—edulcorate, precipitate and separate the alumine from the iron by boiling in caustic potash. From the clear concentrated fluid, to separate the lime by oxalat of ammonia, and the magnesia by pure ammonia; to evaporate the remaining clear fluid to dryness, and to apply a red heat, in order to burn or volatilize any remaining portions of the tests used in the processes above described. To re-dissolve the residue in order to ascertain by subsequent evaporation the presence and quantity of sulphat and muriat of soda.

7th method. To boil a known quantity of residue of the water, in alcohol, in order to ascertain what salts it may contain which are soluble in that menstruum.