600 DR. A. DUPRE AND F, J. M. PAGE ON THE SPECIFIC HEAT AND OTHER 
from fifteen to twenty minutes were required to bring the temperature of the calori- 
meter to a maximum, or rather to the point whence the temperature began to sink ; for 
the calorimeter frequently remained stationary at its maximum temperature for five or 
six minutes. On this account the correction applied amounted to a considerable frac- 
tion of the total rise observed, and great uncertainty was thereby introduced. 
Having observed the beneficial effect, as regards rapidity of cooling, produced by the 
ring-shaped form of the weights, a hollow vessel of a similar shape was made of very 
thin brass, the liquid being contained in the annular space between the two sides. The 
external diameter of this annular vessel was about 60 millims., its internal diameter 
40 millims., its height 70 millims. The annular space containing the liquid was thus 
about 10 millims. broad, and its capacity about 99 cub. centims. 
The liquid was introduced by means of two openings at the upper part, which could 
be closed by small taps. The total weight of the vessel amounted to 49 - 66 grms. 
The weight of water contained in the calorimeter, together with a weight of water 
equivalent, as regards the specific heat, to the vessel itself, stirrer, and immersed part of 
thermometer, amounted to 1165*905 grms. ; and, as a mean of several concordant results, 
it was found that for every degree Centigrade lost by the empty annular vessel, the 
calorimeter and its contents gained 0°*004 C. 
The annular vessel, after being filled with the liquid to be examined, was heated to 
the desired temperature in an oven, similar to the one used in the previous experiments, 
except that warm water instead of steam was used. By a simple arrangement the tem- 
perature of the water could be kept constant, whilst an effective stirrer preserved a 
uniform temperature in every part. 
When the annular vessel, thus heated, was introduced into the calorimeter, the latter 
reached the maximum elevation of its temperature in five minutes, and did not remain 
stationary, but began to fall at once. The annular vessel was then taken out, the tem- 
perature of the calorimeter again read off at the end of three minutes, and the loss in 
temperature added to the highest temperature previously observed. During the whole 
of the experiment, the water in the calorimeter was kept thoroughly mixed by means of 
a stirrer. In all other respects the experiments were conducted as usual. The results 
are given in Table V. ; they agree very well with those obtained in previous experiments ; 
m denotes the quantity of liquid heated, in grammes. 
