Fig. 11.—Freezing a flask of ammonia to a block of wood.
Spirits of Hartshorn.—Commercial ammonia is actually an aqueous solution of the gas, which dissolves to an abnormal extent in water. When it has been absorbed as much as possible the liquid weighs only 22.25 as much as an equal bulk of water, owing, of course, to the latter’s association with a compound far lighter than itself. So great is the energy of solution that heat is dissipated from the liquid as absorption proceeds. Conversely, if the gas be dispelled by blowing air through strong liquor ammoniac, heat is rapidly absorbed at the expense of surrounding objects. To show this, stand a small flask in a pool of water on a wood block, and having about half filled the flask with fresh ammonia, blow into this through a glass tube connected with the mouth by a length of rubber tubing ([Fig. 11]). No long time should elapse before enough heat has been abstracted from the water to convert it into ice, so that the flask is frozen firmly to the wood.
Another demonstration of water’s avidity for ammonia gas is afforded by the following performance. Erect one large flask (A) in an inverted position, so that the distance between its neck and the table is several inches greater than its own height. Some distance away, as shown in [Fig. 12], erect a small 4-oz. flask (B), and half fill it with a mixture of four parts sal-ammoniac to three parts slaked lime (C). Fit the neck with a cork and a delivery tube, which has been so bent as to pass through a stopper in the mouth and reach nearly to the bottom of a jar (D) packed with quicklime (E).
Another glass tube (F) issues from this chamber—but only from just below the cork’s under surface—and passes upwards into the orifice of the large flask. A square of paper (G, in [Fig. 12]) is pushed over the glass tube and presses against the mouth of the flask.
Fig. 12.—To prove water’s affection for ammonia.
If now the mixture in the 4-oz. flask be warmed, ammonia gas is produced, and having been robbed of moisture by the quicklime through which it passes, travels upwards, and collects in the large inverted flask. When the action has continued for a little while, stop the heating and remove the delivery tube, and bring an open spirits of salt bottle near the inverted flask’s mouth. If dense white fumes are immediately formed, the flask is known to be filled with ammonia gas, and must be corked up.
Fig. 13.—A novel fountain.