  Ammonia should be a perfectly colorless liquid; when concentrated its specific gravity should be 0·9. It must have a pure ammonial odor, and must volatilize without any residue. It must not become troubled when mixed with alcohol, or lime water, otherwise it contains carbonate of ammonia. Neither must it for the same reason, become troubled when tested with a solution of chloride of barium; this is the best test for carbonate of ammonia. Care is to be taken to observe the action of the test on its first addition, for after the mixture has been exposed to the air for a few minutes, a troubling necessarily ensues, because the ammonia abstracts carbonic acid from the atmosphere. When super-saturated with nitric acid, and tested with a solution of nitrate of silver, it must give no white precipitate; otherwise it contains sal-ammoniac. It must give no precipitate with a solution of chloride of barium, otherwise it contains sulphuric acid, in which case, the precipitate will be invisible in nitric acid. It must give no precipitate with a solution of oxalic acid or superoxalate of potash; otherwise it contains lime. When saturated with nitric acid and tested with a solution of yellow prussiate of potash, it must give no precipitate; otherwise it contains copper. When mixed with its weight of oil of vitriol, it must not become brown or black; otherwise it contains empyreumatic oil. As it is quite difficult to obtain ammonia entirely free from carbonate of ammonia, or to preserve it in that state, the employment of ammonia containing a small portion of the carbonate is admissible in the practice of the Daguerreotype. An Army of Subscribers.—It is computed that the regular subscribers to the New York Sun, standing side by side, and each occupying eighteen inches space, would form a line seventeen miles, fourteen rods, and three yards long. Standing with arms extended, and occupying six feet each, they would reach sixty-eight miles, fifty-eight rods and one yard, &c. &c.—Sun. Let us see if we also cannot get up some astonishing statistics: The regular subscribers to the New York Tribune, standing in single file, each holding fast to the other's coat-tail, would form a line 176 miles, 7 rods and one yard long. Allowing that each could hop, skip and jump the distance of 4 yards, their simultaneous performance of this feat would extend from Cape Horn to Baffins Bay. Supposing they all sneezed at once, the vibration of the air would overthrow the spire of Trinity Church. In reading the 48 columns of our double sheet every morning, the distance travelled by their eyes would reach twice round the earth. There! Is that enough?—Tribune. Wonder if the Tribune's calculations is made from the actual measurement of the "tail" of the "old white coat?" If so its not fair, for Horace has the advantage over the modern fashion. |
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