20 ~ apporT—1857. 
placed in a calorimeter, which measure the quantities of heat evolved. We determine, 
in the first place, the relative quantities of heat evolved in the two coils when neither 
of them exerts any exterior action. The apparatus is then arranged so that one of 
the coils may produce exterior work, and we see whether the relative quantities of 
heat remain the same. 
The coils employed were of copper wire covered with silk; they were placed in 
calorimeters filled with rectified oil of turpentine, a non-conducting liquid, of which 
the elevation of temperature was determined. The calorimeters first employed were 
brass vessels, of which the annular form would allow of the introduction into the 
interior of the coil, of a cylinder of soft iron, or of the body upon which the exterior 
action was to be exerted. Subsequently glass calorimeters were made use of. The 
calorimetric methods of M. Regnault were adopted. 
In operating with a brass calorimeter and a cylinder of soft iron in the interior of 
the coil, currents of induction are developed in the walls of the calorimeter itself, 
which evolve a great quantity of heat; the experiments made in this way conse- 
quently present a very considerable source of error, but they demonstrate that the 
exterior work exerted by the current is very considerable ; in fact, the excess of heat 
betrayed by the calorimeter containing the soft iron, sometimes rises to #th of the 
heat evolved in the coil ‘tself. 
With glass calorimeters, after the climination of numerous causes of error which 
render these experiments very delicate, a negative result was obtained, that is to 
say, the relative quantities of heat evolved in the two coils were found not to be 
modified when one of these coils produced an action exterior to itself by induction. 
The following are the numerical results of the last experiments which were made:— 
Elevations of temperature of the calorimeter containing 
the coil which exerted an exterior action. 
Cc —_~——_ 
Observed. Calculated. Differences. 
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From this we must conclude that the heat evolved is the same in the two cases, 
and that it is not in the part of the current which exerts an exterior action that we 
must seek for the modification which the interior work must undergo under these 
circumstances. 
Description of an Arrangement of Grove’s Battery. 
By G. Jounstone Stoney, A.M, WRIA. 
The earthenware cells in this arrangement were the ordinary flat cells commonly 
used for Grove’s battery, consisting of flat porous cells containing nitric acid, placed 
within outer cells of glazed earthenware containing acidulated water. 
A sheet of platinum foil hangs into each cell of nitric acid, and on either side two 
parallel plates of zinc stand in the acidulated water of the outer cell. A stout copper 
wire effects the necessary connexion between the two zinc plates of one element and 
the platinum of the next. This connecting wire takes a form somewhat resembling 
that of an S, being first soldered along the top of one zine plate; then after a semi- 
circular bend brought along the top of the other zinc plate of the same element and 
soldered to it, and finally, by a second semicircular bend, brought along the top of 
the platinum of the next element and soldered to it. The same mode of connexion 
was of course repeated throughout the battery, with the exception of trifling and 
obvious modifications at the end of each trough of cells. The soldered joints were 
varnished; each of those which attach the platinum plates was further protected. 
from spatters and fumes by a piece of loose gutta-percha tubing, which was slipped 
lengthways over the wire after its under side had been slit for the platinum foil to 
pass through. 
The S-shape of the connecting wires admits of any set of metals being at any 
moment withdrawn or introduced without disturbing the others. 
