Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/242

 This precipitate, after being carefully separated, edulcorated, dried, and ultimately heated to redness with wax in a platina crucible, weighed exactly 14 grs. It appeared in the form of a red-brown magnetic powder.

6. Since therefore 50 grs. of crystallized green sulphat of iron gave 14 grs. of this oxyd, the 7,2 grs. of oxyd obtained from 50 grs. of residue, would represent 25,7 grs. of green sulphat of iron; and 11,59 grs. of oxyd (which is the quantity contained in an English pint of the water), would represent 41,4 grs. of that salt.

§ IX. Sulphat of Alumine.

1. Fifty grains of residue were boiled in two successive lixivia of caustic potash (as in § VIII. 1), so as to take up all the alumine present ; the residue was separated and well washed, and the washings were added to the alkaline solution. The clear liquor had a brownish colour, and on being tried with muriatic acid and prussiat of potash, a blue tinge was produced, which appeared to have arisen from a few particles of oxyd of iron which were suspended