

CONSTRUCTION OF APPARATUS, 



169 



are now attached to the holes of the ring ; they are bent more than 

 required, as shown in fig. 120, a, and will thus press firmly against 

 the rings by their own elasticity. Into the top of the short cylinder, 

 4, a flat cork is fitted, which has a hole through the middle large 

 enough to receive a glass tube with an internal diameter of about 

 l cm ; the tube is 6 or 7 cm long and fixed into the aperture with 



FIG. 120 (| real size). 



sealing-wax in the following manner. The cork is pressed down 

 into the cylinder until the edge of the latter projects about l mn *-5 ; 

 in the depression thus formed sealing-wax is melted all round and 

 made to adhere firmly to the glass. This last operation is best 

 performed with the help of a blowpipe, which is used for directing 

 the point of the flame of a spirit-lamp upon the sealing-wax, as shown 

 in fig. 121. 



FIG. 121 (an.proj. | real size). 



The blowpipe is in its simplest form a conical tube of brass about 



-" em long, bent near one end, which has a fine aperture, while that of 



he other end is about 9 mm wide. The blowpipe may be used for 



Jie soldering of small objects or whenever great heat is required; 



n using it the air must be projected by the muscles, not of the 



