Decomposition of Water and other Bodies.
The most simple way of performing this experiment is, to bring the wires coming from each end of the battery into a vessel of water. A profusion of bubbles of gas will appear to be given out from each wire, as far as they are immersed in the liquid. The nearer the wires are brought together, so as not to touch, the more rapidly the decompo sition goes on. The gas produced from the wire coming from the zinc end of the battery, if the wire be of gold or platina, is found to be oxygen gas ; but if the wire be of any more oxy dable metal, no gas will appear, but the wire becomes oxydated. The gas furnished by the wire from the copper end of the battery, or whatever kind of metal the wire may be, is pure hydrogen. If the immersed part of this, however, be previously oxydated, no gas will be observed for some time, the hydrogen be ing employed in reducing the oxide upon the surface.
Both the gases are furnished from the decomposition of the An apparatus more convenient for this experiment, and at the same time fitted for collecting the gases, is shown in fig. 4; c g, is a cup of glass capable of re ceiving the glass tube, h; E c, and f are two wires of platina, fitted into two holes perforated in the bottom of the glass cup ; the tube, li, which is close at the top, is first filled with the wa ter or other liquid, and the cup inver ed upon it; the whole are then sud denly returned into their erect position. This apparatus is then placed in the frame, fig. 5; AB CD are four pieces of brass, united together by the pieces of glass, F and G, and supported by four legs, through which also the brass rods, H and K, are passed. It is plain, the two sides of this frame are insulated with re. spect to each other, at least as much as is necessary for any galvanic experiment. The part f, in fig. 4, being introduced into any of the holes, such as II in, the opposite end, F, is made to rest on the opposite brass rod, K. If the wires from the battery be now con nected with the frame at H and K, the gass will instantly begin to rise from the wires, c and z, up into the tube, while the liquid descends and occupies the cup.
A number of the apparatus, such as fig. 4, may be employed at the same time ; and if the different tubes are fill ed with different liquids, such as the va rious solutions of salts, and the communi cation of each occasionally cut off, by placing some non-conductor at E, their relative conducting powers may be ascer tained.
If two tubes of smaller size be placed, one over the wire, z, and the other over that of c, the gases may be collected se parately.
If the tube contains a metallic solution, such as silver, lead, or copper, the wire from the copper end of the battery will afford no gas ; but the metal of the solu tion will be reduced. Let the glass ves sel A, fig. 6, have the two tubes, z and c, ground into its two necks. At the ends, z and c, of the tubes, are tied bits of bladder, so that any liquid in the tubes may have no tendency to enter the vessel A. The vessel being previously filled with some liquid, the tubes are so inserted that no air may exist between the ends of the tubes; the tubes are also provided with two small caps of ivory or wood, through which the platina wires, p p, are passed, reaching the bottom so near as not to pierce the bladders. The tubes being filled with water, and the wire from the zinc end of the battery connected with the wire of tube z, while that of the cop per is attached to that of tube c, the de composition of water will speedily com mence, the wire in z affording oxygen gas, while that of c affords hydrogen gas. In a very short time, the liquid of the tube a will be found to contain muriatic acid ; or, rather, the oxymuriatic ; and the tube, c, will at the same time be found to con tain a fixed alkali. If the tubes be filled with infusion of cabbage, the signs of al kali and acid are very soon observed, from the liquid of z becoming red, and that of c green. If the connection be re. versed, the liquids repass to the blue co lour, and if the process be continued, that of z becomes green, and c red.