28 



ATTAINMENT OF VERY LOW TEMPERATURES. 



eight liters of liquid air. With these quantities the apparatus could 

 be run for about thirty minutes. With the apparatus having the second 

 regenerator coil, which did not require carbonic acid, five liters of liquid 

 air fully sufficed to cool the apparatus in the first place and to cool the 

 hydrogen during a run of more than twice the duration of the former 

 experiments. 



The collecting chamber referred to on page 20 is a cylindrical brass 

 box about 80 mm. in diameter and 100 mm. high. The tube y is con- 



FiG. 9. — Collecting chamber. 



nected by means of a piece of wide rubber tube with a brass tube of 

 similar diameter which dips about 50 cm. below the surface of the 

 water in a tank Q, fig. 8. The tube u. is of glass, joined by means of 

 a socket with the cylinder P, and by a cap with the pipe through 

 which water is discharged from the water separator D, fig. 8. By 

 means of this arrangement the gas discharged together with the water 

 is saved. The pipe ^i is connected by means of a crosspiece with the 

 body of the apparatus and with the two cocks O and O' . The cock 



