PROCEEDINGS OF 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 points. 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 



