Instruction in chemical analysis : (Qualitative) / With a preface by Prof. Liebig. Edited by J.L. Bullock.
- Carl Remigius Fresenius
- Date:
- 1846
Licence: Public Domain Mark
Credit: Instruction in chemical analysis : (Qualitative) / With a preface by Prof. Liebig. Edited by J.L. Bullock. Source: Wellcome Collection.
117/412 page 95
![§ 87.] by vigorous stirring with a glass rod ; even should the solution be so extremely dilute as to forbid the formation of a precipitate ; yet the lines of direction, in which the glass rod has moved along the sides of the vessel, will after the lapse of some time appear distinctly as white streaks. Chloride of ammonium and salts of ammonia in general, fail to dissolve the basic phosphate of mag- nesia and ammonia, but this double salt is soluble in free acids, even in acetic acid. 8. Oxalate of ammonia (but not free oxalic acid) produces a white precipitate of oxalate of magnesia. (Mg 0, 6.) Salts of ammonia prevent its formation. 9. Sulphuric acid and hydrofluosilicic acid fail to precipitate salts of magnesia. 10. If magnesia, or a salt of magnesia, be moistened with solution of protonitrate of cobalt, and subsequently exposed upon a charcoal support to the continued action of a strong blow-pipe flame, a mass will be produced of a faint flesh tint, which becomes distinct only upon cooling, but is never very intense. He capitulation and remarks.—The difficult solubility of the hydrate of magnesia, the ready solubility of the sulphate of mag- nesia, and the disposition of salts of magnesia to form double salts with ammoniacal compounds, are the three principal points in which magnesia differs from the other alkaline earths. We select for the positive detection of magnesia invariably the reac- tion with phosphate of soda, applied in conjunction with ammo- nia. Should barytes, strontia, or lime be present, these earths are to be removed first, before proceeding to apply the special test for magnesia; this removal may be effected either by heating the fluid under examination with carbonate of ammonia in con- junction with sal ammoniac, or by heating it with sulphate of potass and oxalate of ammonia in conjunction with sal ammoniac. The detection of barytes is an easy task under any circumstances,](https://iiif.wellcomecollection.org/image/b29300940_0117.jp2/full/800%2C/0/default.jpg)
