244 MR. H. F. BAXTER’S EXPERIMENTAL INQUIRY AS TO THE EXISTENCE 
tain, if possible, the existence of the current, an accurate description of its delicacy 
will not be necessary. It is sufficiently so to indicate the existence of a current during 
the combination of an acid with an alkali, such as very dilute solutions of nitric acid 
and of potash, when separated by a membrane. 
In several unsuccessful experiments, the following electrodes were used: — Two 
platinum wires, ^th of an inch in thickness and eleven inches in length, were pointed 
at one extremity, to be easily inserted into a blood-vessel or an organ, and coated with 
sealing-wax for about two inches, leaving the extreme point bare to the extent of 
one-fourth of an inch, the other extremities being attached to the galvanometer. 
But during the inquiry, in consequence of the stiffness of the wires forming the elec- 
trodes occasioning a motion of the whole instrument, when making and breaking 
contact, the following alteration was made in the arrangement. Thick copper wires 
ten inches in length were connected with the galvanometer by the screws, and each 
of the free extremities so bent as to rest in a separate wooden cup containing mercury. 
A platinum plate, an inch square, was attached to one extremity of each of the platinum 
electrodes to increase the extent of surface, and being placed in the wooden cups, a 
communication was formed with the galvanometer by means of the mercury, the 
pointed extremities serving, as before, to be inserted into the different parts of the 
animal. Great care was taken to ascertain that the different contacts were perfect, 
and no result upon the needle occurred from the whole arrangement, when a circuit 
was formed with a weak solution of salt, or water, previous to each experiment. 
It will be unnecessary to relate the experiments, thirteen in number, upon cats, 
kittens, a guinea-pig and rabbits, in which an endeavour was made to ascertain 
whether the effect of a diverted current might not be obtained by inserting the elec- 
trodes into the portal vein alone, supposing that the stomach and liver formed poles 
similar to those of a galvanic circle ; or whether a current might not be obtained by 
inserting them into the portal and hepatic veins. These failures, combined with 
theoretical reasoning, led to the supposition that the effect sought for existed in a 
different quarter. The inquiry will therefore commence with relating the last of the 
unsuccessful experiments. 
Experiment 1. — Rabbit, six weeks old. {a). One electrode inserted into the vena 
porta, the other into the vena cava, at the entrance of the hepatic veins ; no effect. 
(b). Caput coli, and a vein coming from the same part ; a slight effect appeared : the 
electrodes were cleaned and reinserted, but the same effect did not occur, (c). Stomach 
and liver, {cl). Stomach and vena porta, (e). Stomach and gall-bladder ; no effect. 
In these and the following experiments the electrodes were cleaned after the for- 
mation of a previous circuit, whenever the substances adhering to them might 
influence the result. Repeating the experiments of Matteucci and of Donne, only 
once did the effect occur, and that but slight, in the guinea-pig. The following fact 
may perhaps account for it. 
Instead of the plates dipping into the mercury, the points were used for this pur- 
pose, and the surface of the plates served to form the free extremities of the electrodes. 
