ALDINI’S. IMPROVEMENTS IN GALVANISMs 
small piece of wire to the dens sapientia, 
diawing it gradually overits surface; he then 
applies it to the next tooth, repeating the 
operation, and proceeds in like manner with 
the rest till he comes to the diseased tooth, 
which discovers itself by a violent pain, pro- 
ducing an involuntary commotion in the 
body. It is always remarked, that when 
this tooth is extracted, it exlubits a carious 
art not before visible. ‘This method, there- 
re, is of great importance, as it frequently 
happens in such cases that the dentist, not 
being able to distinguish the diseased tooth 
from the rest, is obliged to draw some that 
are sound before he can discover it.” 
Several experiments on the action of 
the galvanic pile on the blood, bile, 
uritie, and other animal secretions fol- 
low. They deserve to be recorded, but 
nothing conclusive can be deduced from 
them, nor is it at all certain whether the 
_ change is any more than purely chemical. 
Two interesting dissertations follow, 
which were read by the author of the 
_ Institute of Bologna in the years 1793 
and 1794. ‘They are partly historical of 
the discoveries relating to galvanism, 
partly experimental, and partly contro- 
versial. ‘The latter chiefly turns upon 
the opposite systems adopted by Galvani 
-vand Volta, the former supposing the 
galvanic action to originate in the living 
animal as a consequence of its organiza- 
tion, the latter ascribing the contrac- 
tions only to external electricity, pro- 
ceeding from the armatures, and not to 
any electric virtue in the animal. 
Three other appendixes are added to 
this volume. ‘The first contains a sum- 
mary of the experiments performed on 
_ the body of a malefactor hanged at New- 
ate, whilst Professor Aldini was in 
ondon. ‘They have already been pub- 
lished separately, but they well deserve 
a place in this collection. 
The second appendix contains a re- 
port of similar experiments made by 
Vassali, Cardi, Giulio, and Rossi, on 
three criminals decapitated at ‘Turin. 
The only circumstance enlarged on, is the 
much-questioned sensibility of the inyo- 
luntary organs to galvanic action in 
warm-blooded animals. ‘his sensibi- 
lity is denied by Volta, and, as we have 
before mentioned, could not be detected 
by Aldini in the heart; however, the 
above experimenters fully ascertained it. 
‘They observe, ; 
«© We tried the influence of galvanism on 
the heart in three different ways. 
« Ist, Inarming the spinal marrow by means 
of a cylinder of lead introduced inty the canal 
923 
of the cervical vertebra, and thus conveying 
one extremity ofa silver arc over the surface 
of the heart, and the other to the arming of 
the spinal marrow. The heart of the first 
individual subjected to our experiments ex- 
hibited very visible, and very strong con- 
tractions. ‘The experiments were made with- 
out the intervention of any kind of pile, and 
without any armature applied to the heart. 
It is very remarkable, that when the forme 
is touched first, and then the arming an 
spinal marrow, the contractions of the heart 
which follow are more instantaneous and 
stronger, than when the arming of the spinal 
marrow is first touched, and then the heart. 
In a memoir on galvanism, read in the last 
public sitting of the academy, I gave an ac- 
count of a great number of experiments, - 
made especially on frogs, which exhibited 2 
similar phenomenon. In these animals £ 
observed, a great number of times, that when 
the arming of the crural nerves was touched 
first, and then the muscles of the thigh, 
there were no contractions, or the contrac- 
tions were exceedingly weak ; and, on the 
other hand, that when the muscies of the 
thigh were first touched, and then the arming 
of the crural nerves, as long as the least vitality 
remained in the organs, the contractions of 
the muscles were constant and violent.” 
The second experiment was by arming 
the par vagum and the great sympathe- 
tic nerve. The third was by the pile 
itself, composed of fifty plates of silver 
and an hundred plates of zine. Here, 
«© By making the negative extremity of the 
pile to communicate, by means of respective 
conductors, with the spinal marrow, or 
merely with the piuscles of the back or breast, 
laid bare, and the positive extremity imme- 
diately with the heart, instantaneous and 
violent contractions were obtained ; and the 
contractions were produced also when the 
heart was made to communicate with the 
negative extremity of the pile, and the spinal 
marrow with the positive extremity. 
«© We shall observe, in regard to con- 
tractions of the heart, that of all its parts the 
apex is the most susceptible of motion, and 
the most sensible to the galvanic influence: 
we must observe also, that the contractions 
produced by communication with ‘the pile 
were not only strong, but that they con- 
tinued a long time even after the communi- 
cation was destroyed.” 
The last appendix relates an experi- 
ment on the transmission of galvanism 
through a considerable extent of water 
in Calais harbour, ’ 
The contents of this volume are some- 
what desultory, but the experiments are 
so numerous, so wonderful, and so well 
contrived, and it contains so many cu- 
rious conjectures and remarks on the 
theory of galvanism, that it must be 
* 
