·90875 | 24·386 | ·95125 | 12·446 | ·99375 | 1·527 ·91000 | 24·019 | ·95250 | 12·111 | ·99500 | 1·220 ·91125 | 23·653 | ·95375 | 11·777 | ·99625 | ·914 ·91250 | 23·288 | ·95500 | 11·444 | ·99760 | ·609 ·91375 | 22·924 | ·95625 | 11·111 | ·99875 | ·304 ·91500 | 22·561 | ·95750 | 10·780 |1·00000 | { 0 ·91625 | 22·198 | ·95875 | 10·449 | | {or Water. ----------+------------+----------+------------+----------+------------ ⁂ The specific gravity of mixtures of pure solution of ammonia and pure water is precisely the mean of the specific gravities of their constituents. (Davy; Dalton; Christison.) In all solutions of ammonia, a quantity of anhydrous ammonia, weighing 212-1/2 gr., displaces exactly 300 gr. of water, and reduces the sp. gr. of the liquid to the extent of ·00125. (Griffin.) The strongest solution of ammonia which it is possible to prepare at 62° Fahr. has the sp. gr. ·87500, and contains 34·694% of pure ammonia, by weight, or 21,251 gr. per gallon. (Griffin.)[46] [Footnote 46: Mr Griffin, in his ‘System of Ammonimetry,’ calls every 212-1/2 gr. of anhydrous ammonia a TEST-ATOM; and every 7 water gr. measure, a SEPTEM. Thus, a gallon of water (= 10 _lbs_) contains 100,000 septems. The degrees of his AMMONIA-METER range from 1 to 100, and indicate the number of test-atoms of ammonia in one _gal_. of the liquid.] =AMMONIUM.= The name given to a group of atoms, which play the part of a compound basic, radical, or metallic element. This substance, whose formula is NH_{4} or (NH_{4})_{2}, has never been isolated, although capable of forming most stable salts with the various acid radicals. Several attempts have been made, however, to obtain this compound radical, or group of elements, in a free state, and with more or less success, but on account of its great instability it invariably decomposes when set free into ammonia and hydrogen. Ammonium salts are some of the most important chemical agents, and are usually recognised as follows, ammonia solution, however, usually acting in exactly the same manner as a solution of ammonium hydrate:——By imparting a deep blue tint to solutions of salts of copper. By exhalation of ammoniacal gas (recognised by its odour), when triturated or mixed and heated with caustic potassa, soda, or lime. Added to a solution of bichloride of platinum, they produce a heavy yellow, crystalline precipitate, consisting of minute octahedrons easily discernible under the microscope. With protonitrate of mercury, a black precipitate. With bichloride of mercury, a heavy, white precipitate. With a concentrated solution of tartaric acid, a crystalline, white precipitate, nearly similar to that given with salts of potassa. They are nearly all soluble in water, volatile, and crystallisable.