582 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
drawn from B into A by sucking at G ; ^ is then closed and tbe box A 
is filled with water at tbe ordinary temperature through the opening c. 
The cap c is then screwed on and the water in B is heated by the 
Bunsen H to 60°-70°, as registered by the thermometer T. The cock h 
is again opened a little so that the water only flows from the exit tube 
drop by drop, and the apparatus is allowed to gradually get warm up to 
a temperature about 2° higher than the temperature required. The 
cock h is then fully opened and at the same time the tube d is pressed 
so far inwards that the outflowing water only falls drop by drop. The 
Fig. 85. 
clamping screw s' is then fixed and the apparatus left to itself for a 
short time and the rise or fall in temperature noted. The tube d is 
then moved either way through definite intervals until the desired 
constancy of temperature is obtained. 
The means by which this constancy of temperature is obtained 
appear somewhat complicated. Within the box A, opposite the inlet 
tube a (fig. 87), lies a metal cylinder g. In the bottom of this is the 
socket l into which the tube a passes. In front the cylinder g narrows 
down to the tube m in which is a freely movable piston h . The piston- 
rod o terminates in a flat plate p which lies exactly opposite to the exit 
