USEFUL MICROSCOPE ACCESSORIES 



127 



This flame is always burning when the gas is turned on at the 

 gas main; its height is regulated by the screw S so as to be from 

 3 to 4 millimeters high. If, as often happens, this tiny flame 

 cannot be lowered to the proper size, remove the screw S, and 

 drop into the hole a small fragment of very soft annealed copper 



FIG. 72. Burner for Microchemical 

 Analysis. 



FIG. 73. Burner for Microchemical 

 Analysis. ( X |.) 



wire, replace the screw and turn until the copper fragment has 

 been crushed sufficiently to partially obstruct the flow of gas. 

 Turning the stopcock A lights the large burner and serves to 

 regulate the size of the Bunsen flame. The burner is not sold 

 with the ring R, as shown in the figure, but this attachment can 

 be made in a few minutes by fastening a bent copper or brass 

 wire to a split brass ring which may be raised or lowered and 

 maintains its position through friction, or, if possible, a heavier 



