86 
PROFESSOR KOPP ON THE SPECIFIC HEAT OF SOLID BODIES. 
the glass a from the one vessel to the other must be effected in an instant, and none of 
the liquid in the glass must touch the cork. 
The calorimeter H stands upon a support G (fig. 2)*, on which there is an oval metal 
plate o. In this there are three depressions, in which fit the three feet of the calori- 
meter (they are made of very thin hard brass wire). The calorimeter is oval-shaped, 
and is made of the very thinnest brass plate. In it a brass stirrer fits, made of two 
parallel plates of brass of the same thinness, which are joined below by thin wires, and 
provided with a thin wire ending in a little button i, which serves as handle. The plates 
of the stirrer are perforated in such a manner that the glass a and a thermometer can 
be passed through them. Fig. 4 shows more distinctly the construction of the stirrer, 
also the section of the calorimeter. 
For the experiments, the calorimeter is always filled, as nearly as possible, with the 
same quantity of waterf. The stirrer is immersed, and a thermometer f dipping in the 
water gives its temperature, which is kept uniform by an upward and downward uniform 
motion of the stirrer. When the tube a is brought into the water of the calorimeter, it 
is fastened^ in the clamp of the holder K, which is arranged like the pincettes used for 
blowpipe experiments, so that it stands on the bottom of the calorimeter, and then the 
stirrer is set to work. This motion of the stirrer, and therewith of the water, must be 
moderate and uniform in all experiments ; this is of some importance for the uniformity 
and comparability of the experiments. The temperature indicated by the thermometer 
f rises and soon attains its maximum, which continues for some time, and can be observed 
with certainty. With this the experiment is concluded. The tube a can be taken from 
the calorimeter, dried, and used for a new experiment. 
The increase of temperature produced in the calorimeter by the tube a and its con- 
tents, would be incorrectly given if the warmth of the body of the operator, who moves 
the stirrer and observes the thermometer, acted on the calorimeter. This is prevented 
by a glass screen g g g g, fig. 2, which is fitted in the brackets h h, and above which the 
handle of the stirrer projects. 
1 8. This process for determining the specific heat of solid bodies, the details of which 
are more minutely discussed in the sequel, has advantages over those hitherto prin- 
* In making the experiment, the actual distance between the calorimeter and the heating apparatus must be 
greater than is indicated in the figure, but not so great that the glass a cannot, by a rapid motion of the arm, 
be transferred from the mercury-bath to the calorimeter. 
t This is most conveniently effected by laying across it a bridge with a stem directed downwards (fig. 3), 
and adding water until it touches the point of the stem ; and the calorimeter, which now contains almost the 
requisite quantity of water, is placed on the balance, and the filling completed by means of the dropping-flask 
(fig. 8). The construction of the latter is readily intelligible : it is held by the cork between two fingers, and 
by approaching the hand to the bottom of the flask water commences to drop. When the flask is not in use 
the tube, which fits air-tight in the cork, is raised, so that it does not dip in the water, and thus the water is 
prevented from escaping. 
+ Fig. 5 shows in a section the glass a, with its contents, and the thermometer / immersed in the water of 
the calorimeter. 
