THE REGULATION OF TEMPERATURE. 



73 



(S^ which is not ordinarily in use. The water, heated by the stoves 

 (S, S), is pumped up through the tubes (C, C) at the rate of about 500 

 liters per minute. At the top of D it is delivered into the space (E, E), 

 whence it returns to the bottom of the outer cylinder to be reheated 

 by the gas stoves and again pumped up through the tubes (C, C). In 

 its downward course the water passes over the outer surface of A and 

 also over the lamp compartments (L, L, L, and L, Figure 38). In the 

 smaller baths there are 6 or 8 of these lamp compartments, and in the 

 larger ones 8 or 12. They are distributed in pairs, one in each pair being 

 located directly over the other. 

 The circular openings, through 

 which the lamps are introduced 

 from the outside, are closed by 

 means of caps, one of which (Z) is 

 shown in Figure 38. Below the 

 inner compartment (A, Figures 38 

 and 39) is the disk (P) , which pre- 

 vents the water which has been 

 heated by any of the gas stoves 

 from rising directly against the 

 bottom of A. In Figure 39, there 

 are also to be seen three tubes, 

 indicated by dotted lines, which 

 serve as passage ways between the 

 exterior and interior for the intro- 

 duction of thermometers,\vires, etc. 

 Figure 40 is a horizontal section 

 of one of the smaller baths, in 

 which the positions of the pumping 

 tubes are indicated by C, C, and 

 those of the lamps by L, L, L, and L. The entrance to the inner bath 

 (A, 150 millimeters in width) is closed by the plate-glass door (I, Figure 

 40) and by the hollow metal door (M) . There are two such doors, as 

 will be seen in Figures 41 and 42. The lower one, which is opened only 

 when it is necessary to introduce or remove the cells, is packed with 

 hair. The upper door, on the other hand, must be opened whenever an 

 observation is to be made. On this account, it is provided with an inde- 

 pendent temperature-regulating device, portions of which can be seen in 

 Figure 43. By means of this, the door is prevented from cooling down 

 when open. The space between the inner glass door and the outer metal 

 doors is about 40 millimeters in width. It is occupied by a brass frame, 

 as large as the glass door, which is filled with minute doors, any one of 

 which can be opened independently of the others. Between this frame 

 (which is placed close to the glass door) and the outer metal doors is a hair- 

 filled pad, which is so divided that any small portion of the frame of brass 



Fig. 40. — Brass-copper bath for high tempera- 

 tures. Horizontal section. 



(A) Inner bath; (C) and (C) pumping tubes; (L) , 

 (L), (L), and (L) lamp compartments; (/) 

 plate-glass door; (M) lower hollow door filled 

 with hair. 



