GALVANISM. 
galvanie circle, and in any way influence its effect. The _ History. 
+ Dr Wells wrote an interesting paper on given, 
which was also published in the Philosophical Transac- 
tions of London. He three distinct objects of 
inquiry, which, at the time when he wrote, embraced the 
ts that were the most general subjects of discussion. 
Te, ens inizuises, ms whether the pac saeco — by 
Galvani depends upon any property i nt in the ani- 
Sat bedpparpindinenile. In the second , he in- 
quires into the,conditions that are necessary for its excite- 
ment: And lastly, he examines how far it ought to be 
considered as identical with electricity. Dr Wells coin- 
cidesin opinion with Volta, that the contractions of the 
upon icity liberated by some 
independent of the animal body, and that the 
moisture, which is present in all , is the immediate 
cause of the facility with which the effect is produced. 
He disco we nner a t wee oes charcoal may be 
employ one metals, for exciti 
the influence ; and also that the influence, when excited, 
may be conducted by charcoal. He argues at length 
against the s of Volta, respecting the ce 
tion of the electricity by the contact of the two metals, 
and urges as a decisive objection to it, that the moisture 
which is attached to the animal, ht to serve asa 
conductor, and equalize their electrical condition, with- 
out their being absolutely brought into contact. 
Dr Wells made some curious experiments upon the 
effeets that were produced on the power of the metals 
and on charcoal by. friction; after this operation he 
found that one of the substances alone was.snflicient to 
uce the contractions. As it appeared that the fric- 
ion did not immediately communicate electricity tv the 
body that was rubbed, it must be supposed, that some 
change was brought about in its nature, by which its 
different parts were enabled to act upon each other, in 
the same manner with two distinct substances. He is 
decidedly of opinion, that galvanism is identical with 
electricity, hecause every substance. which is a .conduc- 
tor of one of these principles, is also a conductor of the 
- A very ample and elaborate memoir, on the sub- 
ject of animal icity, was drawn up bya committee 
of the French Institute, which, besides. examining all 
the opinions and controversies that existed on the sub- 
ject, contained an account of a great variety of original 
i The committee was ; of some 
of the most celebrated chemists and natural philoso- 
of France ; Guyton, Fourcroy, Vauquelin, Hallé, 
Sabbatier, Pelleton, Charles, They ar- 
aige Sha wnteselaet Shes report under six heads ; 
1. They examine the different circumstances which in- 
fluence the nature of what they call the animal arc, by 
-which they mean, that part of the galvanic circle 
which consists of the parts of the animal. They con- 
eeive that the animal are may consist of nerve only, but 
in this opinion itis probable that they were mistaken. 
They found that cutting a nerve across did not prevent 
the passage of the influence, provided the eut ends 
were laid close together, and also. that it was trans- 
mitted through di ts. of the same animal,. or 
even through parts of i animals, provided they 
were in perfect contact. They observe, that when a 
nerve is made part of the circle, muscles are thrown 
intocontractions towhich the extremities of the nerve are 
distributed, not those which are contiguous to the trunk 
of the nerve. In the 2d place, they examine the na- 
ture and disposition of what is called the excitatory arc, 
or the metallic part of the circle. 3d, They inquire in- 
to the circumstances which enter into. the action of the 
VOL. X. PART I. 
81 
Ath head consists of the means which may be employed 
for varying, diminishing, or restoring the sensibility of 
the phe» to the galvanic influence. In this part, the 
mention the effects of immersing the animal in a fluid, 
or in an unrespirable gas, so as to produce suffocation, 
when the susceptibility to the galvanic influence was 
either destroyed or much impaired; but the effects 
-were very various, and difficult to account for in many 
eases. The 5th head consists.of a ison between 
electricity and galvanism ; and the 6th contains a de- 
tail of some experiments which were performed by 
Humboldt, and subjected to the inspection of the com- 
mittee. Many of 
‘ous and interesting ; but they 
that’ some substances, which were good conductors of 
electricity, would not conduct galyanism. See Annales 
de Chimie, xx. 51. 
An ingenious paper was about this time published by Fabroni's 
Fabroni, in’ which he discusses the question -whether paper, 1799. 
the galvanic phenomena are immediately referrible to 
electricity, or whether they ought.not rather to be at- 
tributed to chemical affinity ? He relates many observa- 
tions, that he made upon the chemical action of diffes 
rent metals on each other, when placed in contact; and 
shows, that they were then disposed to oxidate under 
the same circumstances, except that of being in con- 
tact, where, if separate, no effect would have pro- 
duced. He argues, that the facts stated by Galvani, 
Volta, and others, which were conceived by them to 
prove the electrical nature of the phenomena in ques- 
tion, only went so far as to. shew, that electricity was 
in the operation, but did not prove it to be 
the cause of them ; and he is: inclined to regard it rather 
asthe effect, ' 
Fabroni mentions among other facts, that " 
and tin when pure, and kept distinct from other metals, 
will remain a long time without tarnishing, but when 
alloyed, or kept in contact with other metals, they soon 
begin to exhibit signs of oxidation. He remarked, that 
coins composed of a pure metal were more durable than 
such as were composed of a mixture of metals. He 
mentions the corrosion which takes place, when copper 
yoofs are soldered with another metal, and in the 
pe sheathing of ships when fastened with iron nai 
hese phenomena are supposed to depend upon a che- 
mical affinity between the metals, by which their par- 
ticles are. individually attracted towards each o> a 
while the separation of the particles of the solid metal, 
which is caused by their tendency to unite, permits the 
oxygen to act 7 them. “ These facts,” he says, “as 
well as many rs of the same nature, no less com- 
mon than well known, ought to have proved to philo- 
sophers, that the metals, by exercising their mutual at- 
tractive force, must by the same energy diminish their 
pr wars powers of aggregation; that though neither 
of ly may be able to attract oxygen from 
the pORE iy or from water, they may acquire that 
power. by simple mechanical touch as they pass to new 
combinations,” 
iments which he pers 
formed, in order to:observe the comparative effect pro- 
duced, by placing metals first in vessels of was 
ter, then in the same vessels, but not im contact; and 
lastly, in the same vessels, and also in contaet. In the 
two former cases there was no change while 
in the latter there was a considerable of oxida. 
tion. He afterwards entered upon some: speculations 
ah hay 
umboldt’s experiments were curi- yumboldt’s 
pear not to have been, experi- 
in all cases, very accurate ; for he concludes from them, ments, 
