794 



DISTILLATION. 



contact with the tube which contains the hot steam, 

 provision must be made for a frequent renewal of the 

 water in the condenser. 



A simple apparatus of this kind is 

 shown in fig. 390. A wide cylinder 

 of glass, cc, is closed at both ends 

 by corks. A tube a 6, having a 

 somewhat narrower opening below 

 than that above, passes through both 

 corks of the wider tube ; its upper 

 end a is closed airtight by a cork 

 perforated for a narrow tube which 

 leads to the vessel in which the 

 steam is generated. The lower end 

 is loosely placed into the neck of a 

 vessel which serves for receiving the 

 condensed liquid. Cold water passes 

 into c c by means of the narrow tube 

 d, which reaches nearly to the bottom 

 of c c, while the heated water flows 

 off at the top of c c through the 

 narrow tube 0, which is fixed in the 

 side of it. 



FIG. 390 (\ real size). 



The upper cork serves only for keeping the tubes cc and d in a 

 steady position, and need not fit very tight ; but the lower cork must 

 close the lower aperture perfectly watertight, or otherwise the im- 

 pure water in the condenser will run between cork and sides into 

 the receiver, mix with the distilled liquid in it, and render it impure 

 again. The mode of inserting the tube e in the side of the cylinder 

 is the same as that described on page 41, for the contrivance fig. 40. 



The cylinder may be either clamped in the retort-stand, by the 

 narrower portion, or placed into the funnel ring of a filter- stand, 

 so that the shoulder of the wider portion may rest on the ring. 

 The tube d may be attached by a piece of india-rubber tubing to 



