130 ROBERT CHAMBERS. 



As a source for the flame acetylene is to be preferred to ordinary 

 illuminating gas because with the former a narrower flame can be 

 obtained without undue clogging. The acetylene generator in 

 the figure is part of an old bicycle lamp. A more convenient 

 way is to have the acetylene in a small compression tank which 

 can be recharged at a very small cost. If, however, ordinary 

 gas is to be used, one may much improve the gas by passing it 

 through alcohol or benzene. 



J 



FIG. 6. Stages in making needles, a, glass tube with one end drawn out into a 

 capillary, b, good tapering point, c and d, serviceable points, e, tip drawn out 

 into a hair. /, completed microdissection needle, g, needle made on a relatively 

 stout shank. 



The method of procedure in making the glass needle is as 

 follows : 



1. In an ordinary Bunsen burner (or a Mecca burner if hard 

 glass be used) draw out one end of a piece of glass tubing into a 

 straight capillary about 0.3-0.5 mm. in outside diameter (Fig. 

 6, a). Prepare a supply of such pieces with the capillary ends at 

 least 6 cm. long. 



2. Lower the flame of the microburner to the smallest flame 

 that will remain lighted. The microburner should be protected 

 from draughts of air and in semi-darkness so that the flame may 

 show up to best advantage. 



3. Hold the shank of the glass tube in the left hand and, with a 

 pair of fine forceps held in the right, grasp the capillary at a 

 point about 5 cm. from the shank. Bring the portion of the 

 capillary next the forceps over the flame and at right angles to 

 it at a point just over the flame (Fig. 5). Pull gently with the 



