GALVANISM. 



Though we had no great opinion of the 

 medical agency of galvanism, we have 

 lately heard of several very successful 

 cases, one of which in particular was the 

 cure of perfect loss of speech. If the 

 naked metal of the wire from a powerful 

 battery be applied to the skin, it becomes 

 cauterized and blistered. 



If the plate, covered with a moistened 

 sponge, connected with one end of the 

 battery, be applied to "the back of the 

 head, at the same time that the moist- 

 tened fingers of one hand are slightly 

 applied to the other end, a smarting 

 sensation will be felt in the part, and a 

 taste at the same time will be felt in the 

 mouth, similar, but in a greater degree, 

 to that occasioned by the piece of zinc 

 and the shilling when laid upon the 

 tongue. Tliis experiment succeeds the 

 best with a small number of large plates, 

 as much as ten inches square. 



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 water. 



An apparatus more convenient for this 

 experiment, and at the same time fitted 

 for collecting the gases, is shown in fig. 

 4 ; c , is a cup of glass capable of re- 

 ceiving the glass tube, A; E c, and / z, 

 are two wires of platina, fitted into two 

 holes perforated in the bottom of the 

 glass cup; the tube, A, which is close 

 at the top, is first filled with the wa- 

 ter or other liquid, and the cup inver- 

 cd upon it; the whole are then sud- 



denly returned into their erect position. 

 This apparatus is then placed in the 

 frame, fig. 5 ; A B C D 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 /, in fig. 4, being introduced 

 into any of the holes, such as n m, 

 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, //>, 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 

 z will be found to contain muriatic acid ; 

 or, rather, theoxymuriatic ; and the tube, 

 c, will at the same time be found to con- 



