FLASKS. 



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the flask to be emptied to the left, and the one that is to receivd 

 the liquid or culture to the right, alongside the burner. Then 

 the tube of the left-hand flask is opened in the flame by quickly 

 removing the rubber tube with its glass stopper ; while the open 

 tube is in the flame, the glass stopper of the flask to the right 

 is quickly withdrawn, and the hot tube of the first flask is 

 connected with the rubber tube of the second flask after the 

 tube has been cooled. The liquid is poured into the second 

 flask, the bent tube of the first flask being at the same time 

 heated. Then the side tube of the left flask is again introduced 

 into the flame, while the stopper of the right flask is replaced 

 directly after it has been passed through the flame ; finally, 



Fig. 7. 



the left flask is closed in the flame with its tube and stopper. 

 When the operation is quickly performed the danger of con- 

 tamination is almost excluded. 



Pasteur flasks will be found indispensable in certain opera- 

 tions ; for instance, in physiological researches where large 

 quantities of liquids are dealt with. 



The Chamberland flask (Fig. 6) is closed with a ground cap, 

 which terminates in a short, open tube ; this tube is filled 

 with tightly-packed sterilised cotton-wool. 



The Freudenreich flask is constructed on exactly the same 

 principle (Fig. 7, centre) ; it has, however, a cylindrical 

 shape. 



