PROPERTIES OF MATTER IN THE GASEOUS STATE. 
737 
Fig. 1. 
Figure 1 represents the plates and india-rubber rings somewhat separated. 
E. Is the porous plate with the ring of india-rubber outside it. 
FF. The rings which form the two chambers for gas on each side of the plate. 
GG. The tin plates which close these chambers. 
HH. The india-rubber rings which form the hot and cold chambers. 
II. The tin plates which close these chambers. 
KK. Tubes soldered to the tin plates GG to communicate with the chambers 
FF, and 
LM, LM. Are tubes soldered to the tin plates II, to allow of the streams of 
steam or water through the chambers HH. 
Fig. 2. 
L 
K 
M 
Figure 2 shows a section taken along the axis of the rings and plates, showing 
them in position, also the wooden press by which they are held together. 
Conduction of heat. 
12. The circumstance which principally led to the selection of this form of apparatus 
was the necessity of preventing, as far as possible, the conduction of heat from the hot 
to the cold side, through the material bounding the chambers. It will be seen that 
there is no metallic communication from the hot to the cold side, and that all the heat 
5 B 2 
