24 GENERAL TECHNIC 



4. The straight limb may now be drawn to a sharp point and used 

 as a needle. 



VACCINE BULBS 



These may be made of glass tubing, to hold 1 c.c. or more, al- 

 though when a large number are required, it is cheaper to purchase 

 ready-made ampules, such as are shown on p. 215. 



1. Take a piece of glass tubing at least 10 cm. in length, and having 

 an internal diameter of 6 or 7 mm. 



2. Seal one end by heating it in a hot Bunsen or blow-pipe flame. 



3. After cooling, drop in one or two small glass beads, which serve 

 later to aid in mixing the vaccine before it is injected (Fig. 6). 



4. Heat the opposite end and draw out into a wide and stout cap- 

 illary end. 



5. This end may be broken through; the whole ampule is now ster- 



FIG. 6. METHOD OF MAKING A VACCINE AMPULE OF ORDINARY GLASS TUBING. 



ilized by heat, and after it is cooled, the required amount of vaccine is 

 inserted. 



6. The open end is then sealed in the flame by warming the air in the 

 bulb above the surface of the liquid and finally sealing the tip, other- 

 wise the air may expand after heating and cause an explosion at the 

 tip. Care must be exercised not to heat the glass down to the level 

 of the fluid, as this tends to produce steam and to crack the bulb. 



Test-tubes may be drawn out and converted into ampules for hold- 

 ing vaccines, serums, or other fluids. 



1. Thin-walled and sterilized test-tubes of appropriate size are 

 chosen. 



2. The tube is heated at a point near the open end in the Bunsen 

 flame, in the same manner as the glass tubing, i.e., by keeping the tube 

 constantly rotating with a lateral movement to insure uniform heating. 



3. When the glass has become plastic, it is drawn out into a stout 

 stem. 



