GALVANISM. 



tion was placed in the tube, Mr. Cruick- 

 shank observed, that, instead ofhydrogen 

 gas being evolved from the wire, which 

 connected the silver end of the pile, as in 

 the former experiments, the metal be- 

 came revived. 



He next caused the galvanic current to 

 pass through solutions of the muriates of 

 lime and soda. In these experiments, he 

 found the oxygen evolved from the wire 

 of the zinc end very deficient, and a smell 

 of oxy-muriate produced. When gold 

 wires were employed, the gold was dis- 

 solved by the oxy-muriatic acid. Aqua 

 ammoniac being operated upon in a simi- 

 lar way, both the water and the alkali un- 

 derwent decomposition, producing the 

 gases of hydrogen, nitrogen, and oxygen. 

 It is to the ingenious author of the above 

 experiments, that weareindebtedfor the 

 invention of the galvanic trough, a disco- 

 very which very soon superseded the use 

 f the pile, as being more manageable, 

 and attended with less trouble to the 

 operator. It consists of a wooden box, or 

 trough, the depth and breadth of which 

 corresponds with the size of the plates. 

 It is of such a length, in general, as to 

 contain fifty plates, allowing a space of 

 about three-eights of an inch between 

 each pair of plates. The spaces between 

 the plates are formed by grooves, which 

 are to receive the plates. The plates are 

 first soldered together in pairs, one of 

 copper or silver, and one of zinc. The 

 trough being lined with a cement, formed 

 of bees'-wax and resin, the plates, which 

 are previously warmed, are pressed into 

 the grooves, in such order, that the zinc 

 side of each compound-plate may face 

 one way, and the copper or silver the 

 other. 



It will be easily perceived, that there 

 is the strictest analogy between the trough 

 and the pile, in point'of arrangement. See 

 fig.l. 



The pair of plates of zinc and silver, 

 which, in the pile, are simply laid upon 

 each other, are, in the trough, soldered 

 together, and cemented into the grooves; 

 and the cavity or cells formed by the 

 spaces between each pair of plates, in the 

 trough, being filled with a solution of salt 

 or other appropriate liquid, stands in the 

 stead of the pieces of moistened cloth, 

 between the plates of the pile. 



Several powerful troughs were soon 

 after constructed, the effects of which 

 were strikingly evinced, in producing 

 other phenomena, not as yet observed. 

 Very small wires and foils of metal, being 

 exposed in their circuit, were deflagrated 

 with great brilliancy. 



A number of galvanic experiments wer** 

 made by Dr Henry, of Manchester, in 

 which he succeeded in decomposing the 

 sulphuric and the nitric acids, and am- 

 monia. 



Mr. Davy, professor of chemistry at the 

 Royal Institution, made a number of ex- 

 periments, the most particular of which 

 were those, in which he ascertained, that 

 the dissimilarity of metals was not abso- 

 lutely essential to the galvanic process. He 

 succeeded, first, in exciting this energy 

 by means of one metal, the two sides of 

 which were separated from each other. 

 An oxydating liquid, such as an acid, was 

 placed on one side of the plate, and a li- 

 quid, having a contrary effect, on the 

 other. He afterwards produced an effect, 

 though more faintly, by treating plates of 

 charcoal in a similar way. Hence it would 

 appear, from these results, that the dissi- 

 milarity of the metals was only necessary 

 to the furnishing two surfaces of different 

 degrees of oxydability. 



Hitherto it was not generally admitted, 

 that the fluids of galvanism and electri- 

 city were identical. Dr. Wallaston made 

 a number of experiments, which seem to 

 have completely settled this point. He 

 succeeded in decomposing water, by 

 means of a current from the common elec- 

 tric machine. This effect, which had 

 been performed with so much facility 

 with the galvanic apparatus, was previ- 

 ously not known to be able to be produc- 

 ed by common electricity, and had hi- 

 therto appeared the most striking differ- 

 ence between the two principles. 



This ingenious experimentalist made 

 a number of other experiments, tending 

 to throw much light on the means of ex- 

 citing and appreciating galvanic pheno- 

 mena. He immersed each extremity of a 

 piece of zinc and silver in dilute muriatic 

 or sulphuric acid. The zinc, as would be 

 expected, immediately caused the disen- 

 gagement ofhydrogen gas, while no ap- 

 pearance took place upon the silver. As 

 soon, however, as the two metals were 

 made to touch each other at the opposite 

 extremities, bubbles of hydrogen were 

 copiously given out by the silver wire, 

 Any other metal, capable of being acted 

 upon by the acid, being substituted for 

 the zinc, produced with the silver a simi- 

 lar effect. When gold was employed 

 with silver, iron, or copper, in the dilute 

 nitric acid, the same effect was produced; 

 the gold being the same with the silver 

 in the first experiment. 



He made similar experiments, using 

 metallic solutions instead of the dilute 

 acid, Instead, however, of silver or gold 



