CANE SUGAR. 113 



No. 1 places the stopper in position for entrance over the mouth of 

 the glass tube and pushes forward with all his strength. Since the 

 tube at the mouth is considerably constricted, the stopper does not 

 enter. No. 2 now introduces the fang and works the rubber little by 

 little through the narrow opening until enough of it has been buried 

 in the glass tube. In the meantime, No. 1 turns and twists the stopper 

 in any direction which seems likely to promote the progress of No. 2. 



From the time when the rubber stopper first enters the glass tube 

 until the nut (h) is brought down upon it and secured by the brass 

 collar (g), there must be no relaxation of the pressure exerted by No. 1. 

 Otherwise air will enter the cell through the groove on the under side 

 of the fang; or if, as in the earlier work, no safety reservoir has been 

 provided for the gas in the manometer, some of it may escape from 

 the calibrated portion of the instrument. When, therefore, the stopper 

 has been introduced and the fang withdrawn, and it is necessary for 

 No. 1 to remove his fingers from the sides to the top of the stopper in 

 order to make room for the winding operations of No. 2, the stopper 

 is seized and held by the latter until the former has his fingers firmly 

 fixed in their new position. Similar aid is required from No. 2 when, 

 with the winding of the exposed part of the stopper completed, it is 

 necessary for No. 1 to remove his fingers from the top of the stopper to 

 the top of the nut (h). After this change of position has been effected, 

 any desired initial pressure is brought upon the contents of the cell by 

 turning up the brass collar (g) on the nut (h). 



When a cell is to be opened, No. 1 holds the apparatus as in closing 

 and attempts to withdraw the stopper by pulling, while No. 2 admits 

 air to the contents of the cell by inserting the fang between the rubber 

 and the glass tube. But the simple admission of air by No. 2 and the 

 simultaneous efforts of No. 1 do not suffice for the removal of the 

 stopper. It is necessary for No. 2 to work the rubber, little by little, 

 out of the glass tube with the fang, while No. 1 maintains a steady pull 

 upon the stopper. 



It will be seen that both the closing and the opening of the cells 

 required considerable time. In the beginning, each operation con- 

 sumed about 15 minutes. 



The first arrangements for the maintenance of temperature were 

 crude and wholly inadequate. The bath employed in the measure- 

 ments of Series I is shown in Figure 46. It consisted of a double- 

 walled box with two front doors (a and c). The former (a) had a 

 narrow plate-glass window (6), through which the height of the mercury 

 in the manometers and thermometers could be read without opening 

 the inner door. The outer door (c) had in its central part a smaller 

 door (d), which was of the same size as the window (6). The spaces 

 between the outer and inner walls of the box were filled with hair. 

 Between the doors (a and c) a hair pad was placed, which exactly 



