LABORATORY GUIDE IN PHYSIOLOGY. 



2 mm., cut a radial segment about 2 mm. wide. 



(2) Clean the ring and slide with absolute alcohol. 



(3) Fix the ring to the slide with sealing wax, placing 

 the opening in the ring toward one end of the slide. 



(4) Heat the glass tube and draw it to one-half of its 

 orginal diameter as shown in Fig. 1. B. 



(5) Fix the glass tube to the slide, using sealing wax. 

 The tube may be further supported by a few turns 

 of heavy linen thread drawn tightly, tied and fixed 

 in position with drops of melted wax. 



(6) In order not to give too free vent from the cell for 



FIG. 1. Apparatus for forcing a stream of gas or vapor through a cell. 

 For description, see I=b 2 and j>. 



the gas which enters by the tube a bit of soft para- 

 fin may be warmed in the hand and worked, with 

 the point of a scalpel, into the space around the 

 end of the glass tube leaving only a little furrow in 

 the parafin above the tube. 



3. Operation. Fill the gas flask full of water and dis- 

 place it with CO 2 gas. Fill the siphon and adjust 

 apparatus as shown in the figure. During any read- 

 justments of the apparatus the siphon may be kept 



