Automatic Toepler Pump. 865 



It lias been found that very rapid currents of air can be 

 sucked through this trap without a single globule of mercury 

 being carried into the water-pump. 



Two other tubes are attached to the reservoir B, one of 

 which, m, is connected with the regulating apparatus E, and 

 the other, n, with the mercury trap, k. 



The collecting apparatus was designed to enable either the 

 whole or a portion of the extracted gas to be withdrawn and 

 collected. 



In this apparatus the receiving bulb C is in direct com- 

 munication with the stroke-cylinder A by means of the 

 millimetre capillary tube,/, and with the atmosphere by means 

 of a similar tube, </, which is attached to the top of the bulb. 

 The U-tube h connects C with the subsidiary reservoir I), 

 and from the slight enlargement at i a tube, x, is extended 

 downwards and dips into the vessel F. The top of the bulb 

 I) is connected through the ground-glass valve and mercury 

 trap k with the top of the reservoir B, and by the tabe / 

 Avith the middle of its under surface. The essential part of 

 the automatic controlling apparatus consists of two portions, 

 the bulb E with the test-tube p, joined together as shown 

 by the 8-millimetre bore-tube o, and the branched tube 7, 

 which is of the shape shown in the figure, and is constricted 

 to a fine capillary at the point r. 



The longer arm of this tube reaches to the bottom of the 

 vessel E, the shorter to the bottom of the tube p. 



The vessels s and F are arranged so that any overflow of 

 mercury from either of them finds its way into p. 



The tube q is attached to m by rubber pressure tubing, 

 which can be closed by a screw pinchcock at ic, and each of 

 the tubes, I and ,r, are cut and the parts joined by pressure 

 tubing, which in the same manner can be closed by screw 

 pinch cocks. 



The volumes of the various vessels are approximately as 

 fellows : — 



The stroke-cylinder A 300 cubic centimetres. 



The reservoir B 600 „ „ 



The collector C 100 „ 



The reservoir D 130 .. 



The bulb E 150 .. 



It is essential that the U-tube c/, and the tubes ?,/, and cj 

 shonid be over 80 centimetres in length. 

 . The relative levels of the various bulbs are as follows: — - 



The botiom of the reservoir B is placed 30 centimetres 

 below the top of the tube /, and 10 centimetres below the 



