[ 863 ] 



XC. An Automatic Toepler Pump, designed to collect the gas 

 from the apparatus being exhausted. By Bertram D. 

 Steele, D.Sc* 



DURING the investigation of certain dissociating com- 

 pounds containing sulphur dioxide, it became necessary 

 to exhaust constantly certain apparatus for a prolonged period. 

 After several days had been spent in manipulating a Toepler 

 pump of the usual pattern, an automatic Toepier pump was 

 designed and constructed. 



The pump that was required was one which not only should 

 be capable of being worked automatically for long periods, 

 but also one by means of which it should be possible to deliver 

 samples of the extracted gas when desired, and if necessary 

 to collect the whole of such gas for examination. 



These requirements are satisfactorily fulfilled by the pump 

 which is described in the following paper. It will ne best 

 described in three sections, all of which are shown diagram- 

 matically in fig. 1 (p. 864). 



The pump proper is an ordinary Toepler pump, and is 

 represented in the figure by the parts A and B and various 

 adjuncts. 



The collecting apparatus is represented by the parts and 

 D and connecting tubes. 



The automatic controlling apparatus is represented by 

 s, F, E, and y. 



The pump proper consists of the stroke-cylinder A and the 

 reservoir B, these being connected by the U-tube d. This 

 U-tube, which is about 8 mm. in internal diameter, is pro- 

 vided at its lowest point with a short side-tube, by means of 

 which the mercury can be removed from the pump if neces- 

 sary, and it is constricted at one point to a diameter of about 

 2 mm. This constriction regulates the flow of mercury and 

 renders it impossible to break the apparatus by a sudden blow 

 of the mercury, even at the highest exhaustion. The U-tube 

 in its shorter arm is 800 mm. long, in order that either A or 

 B may be put into communication with the atmosphere 

 whilst the other vessel is exhausted. 



The stroke-cylinder A is provided, in the usual manner, 

 with a ground-glass valve, a, and a manometer, 6, and the 

 apparatus to be exhausted is attached on the other side of the 

 phosphoric-anhydride tube and the stopcock, c. 



Communicated bv the Physical Society : read March 11, 1010. 



