92 
History. ism, reserving the consideration of the hypothetical 
opinions to the second division of the article. 
Gay-Lussac These sagacious experimentalists remark, that, next 
and The- to the construction of the pile itself, the most important 
— te discovery was made by Hisinger and Berzelius, who 
1811. *% found that when the electric current decomposed a neu> 
tral salt or an oxide, the oxygen and acid were carried to 
the positive end, and the base to the negative. The 
application of this principle enabled Sir H. Davy to 
Difference effect the decomposition of the alkalies. The authors 
between the moint out the distinetion between the electrical and the 
snd chemi. ¢htemical energy of the pile; actions which are essen- 
cal action, tially dissimilar, and which do not exist in the same 
ratio. They state, that a comparatively few plates, 
with acid int between them, will decompose 
the alkalies ; while a greater number, with water instead 
of acid, will not produce this effect, and will yet exhibit 
a higher electrical tension. The power of the appa- 
ratus was found to be nearly in proportion to the 
strength of the acid employed ; and some comparative 
experiments were instituted, for the purpose o come 
ring the effects of acids, alkalies, and neutral salts, 
The.test which they employed to judge of the quan- 
tity of effect produced by the pile, was the amount of 
gas evolved from a fluid, subjected to the action of the 
wires connected with its two extremities: this they 
conceived was a more exact measure of its energy than 
the different lengths of wire which it was capable of 
consuming. 
When they employed a very powerful battery, it 
" was observed that considerable shocks were given by 
it to an individual ; but that in a chain of four or five 
persons, it was not felt in the centre; and in the ex- 
tremities of the chain, that of the body received 
the greatest impression which was nearest to the appa- 
ratus. This fact is supposed to prove, that the elec- 
tric fluid cannot circulate rrenen the whole circuit, 
according to the Franklinean hypothesis. When the 
battery is put into strong action, its chemical effect, 
é, e. its power of decomposing water, soon declines, or 
altogether ceases, while its electrical tension remains for 
some time longer unimpaired. 
An interesting train of experiments is next detailed, 
in which mercury was interposed between the wires, 
and formed an amalgam with the substance which was 
intended to be decomposed: an arrangement which we 
have already pointed out as having been employed by 
Sir H. Davy in his decomposition of the proper earths. 
They repeated the experiments of this philosopher on 
ammonia, and they formed the amalgam with mercury, 
which he conceived was composed of this substance 
with the metallic basis of ammonia; but they differ 
from him in their idea of its constitution, and sup 
that there is no evidence of the existence of the metal 
of the volatile alkali, although the analogy of the fixed 
alkalies offers so powerful an argument in its favour. 
De Luc’s While Sir H. Davy was pursuing, with so much sue- 
analysis of cess, his interesting researches into the electro-chemical 
od a action of bodies upon each other, M. De Luc under- 
: took to investigate the nature of the galvanic pile, and 
to examine the mode of its operation. After some ani- 
madversions upon the hypothesis of the inherent elec- 
tric energies of bodies, which constitute the origin of 
the train of phenomena that are connected with the 
_. pile, he proceeds to dissect this instrument into three 
ryan Ts parts. He divides it into three separate groups, corre- 
¢ pile. “g onding to what he regards as the three elements of 
the + These elements are the two metals and a 
fluid. They were first placed with the fluid between 
GALVANTISM: 
the two metals ; then'with the fluid in contact with History 
one, and afterwards in contact with the other metal, “-Y™ 
the different groups being kept distinct from each other 
by small wire stands, so as to confine ‘the action to 
that part alone. When the piles were fitted up in these Prarr 
three different ways, a delicate electrometer was at- CCLXII 
tached to each extremity, and they were also connect. Figs. 14- 
ed by the interrupted wire passing through water. ae 
His first set of experiments were made upon ‘the Fig. 19. 
in which the groups were with the fluid First di 
tween the two metals. By means of the electrometer, aoe 
he observed which ends ef the a tus were in the pile, 
positive and negative states respectively ; and he like+ 
wise made some new ‘observations on the direction 
which the electric current takes in its p across 
the water—in the interrupted circuit—and in ‘the 
body of the pile itself. His observations with Observa- 
those originally made by Nicholson, that the extremity: tions on 1 
of the pile which is connected with the wire emitti apie 
oxygen, is positive, and that the current is direct e 
from this to the wire which emits the hydrogen. He anton 
informs us, however, that although electrometers pla+ acted 
ced at the extremities, when they are affected, indicate states. _ 
the electricity to be in the state mentioned above ; yet ‘ 
they are not always both of them affected, sometimes 4 
only the positive electricity is visible, sometimes only = _ 
the negative, while at other times both of them are 
perceptible. He conceives that, from various causes; 
the dpdeic fluid passes through the apparatus with 
different velocity at different times, or through its difs 
ferent parts-at the same time, so as to produce a partial 
accumulation or deficiency : It seems to be always res 
tarded when it passes from the point of the wire into 
water. He observes, that the expressions positive and t 
negative, as applied to the ends of the pile, or to the | 
wires in the interrupted circuit, can only be regarded f 
as comparative terms, because the chemical action of 
the pile goes on as usual in the d sition of was 
ter, although the whole instrument be rehdered posi+ 
tive or negative, by attaching it to the prime conducs ~ 
tor, or to the rubber of the electrical machine. This 
experiment is adduced to prove, that the action of the 
pile is not necessarily connected with the electric ener- 
of the substances that enter into its dsitic 
be pile, when dissected in the first way, with the 
fluid interposed between the two metals, acts in the 
same manner. as if the parts were continuous, except 
that the effect is rather less powerful. 
M. De Luc then examined the action of the pile, when Second 
dissected according to the second arrangement, where section. 
the metals were placed together, and the wet cloth in 
contact with the zine, or ayy re srt eae —— — 
tals; the tern ing separat 
other by the vie ag The extremities of the pile 
indicated to the electrometer the same states of positive 
and negative, as in the former instance, but no shock 
was experienced ; when the wires of the inte 
circuit were placed in water, al h it ap that 
there was a communication established through the 
fluid, yet no decomposition took place, nor did there 
appear to be the retardation of the electric current upon 4 
its entering the fluid, as in the former case. Hence } 
the author concludes, that the electrical and chemical ; 
effects originate from different causes, because in this 5 
state of the instrument the electrical effects continue, 
although the chemical effects are suspended. The Third’ 
third diseection of the pile was now made, i. e. it was section, 
divided into ternary groups, consisting of the metals } 
contiguous to each other, and the wet cloths in contact : 
