PROCEEDINGS OP THE AMERICAN ACADEMY. 



The fractions are drawn into the still through the tube closed by the 

 nipper tap A. The still is exhausted by the tube N connecting the tube 

 O with the vacuum reservoir D. The reservoir C is exhausted by the 

 tube H which connects with the water pump through the tube P. Air 

 is let into the receiver C by means of the cock I, and kept from the 

 still by the cocks E and F. The tube with the stopcocks E and F 

 afford a convenient means for separating fractions without interruption, 

 and without admission of air into the still. The tube M leads to the 

 manometer. By means of a single efficient water pump the entire 

 apparatus may be kept under a tension of 12mm. or less during con- 

 tinuous distillation. By means of common corks, the apparatus is readily 

 set up and easily kept tight by the use of rubber lute. 



The tubes II and N may be given less rigidity by putting them 

 together in sections with connectors. Any water that may occasion- 

 ally run back from the pump is readily drawn out if the pipe P extends 

 to the bottom of the reservoir D. 



The apparatus in this form is especially adapted for the separation of 

 fractions with high boiling ^Joints. For very high temperatures the still 

 must be packed in asbestos. For more volatile distillates a condenser 

 should be inserted between the still and tube 0, best by passing the 

 exit tube of the still through the condenser. Our distillation flasks 

 are made with a high exit tube to give a long neck, which is filled with 



